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  • 122601.
    Zhu, Bin
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi. Hubei University, China.
    Wang, Baoyuan
    Wang, Yi
    Raza, Rizwan
    Tan, Wenyi
    Kim, Jung-Sik
    van Aken, Peter A.
    Lund, Peter
    Charge separation and transport in La0.6Sr0.4Co0.2Fe0.8O3-delta and ion-doping ceria heterostructure material for new generation fuel cell2017Ingår i: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 37, s. 195-202Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Functionalities in heterostructure oxide material interfaces are an emerging subject resulting in extraordinary material properties such as great enhancement in the ionic conductivity in a heterostructure between a semiconductor SrTiO3 and an ionic conductor YSZ (yttrium stabilized zirconia), which can be expected to have a profound effect in oxygen ion conductors and solid oxide fuel cells [1-4]. Hereby we report a semiconductorionic heterostructure La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF) and Sm-Ca co-doped ceria (SCDC) material possessing unique properties for new generation fuel cells using semiconductor-ionic heterostructure composite materials. The LSCF-SCDC system contains both ionic and electronic conductivities, above 0.1 S/cm, but used as the electrolyte for the fuel cell it has displayed promising performance in terms of OCV (above 1.0 V) and enhanced power density (ca. 1000 mW/cm(2) at 550 degrees C). Such high electronic conduction in the electrolyte membrane does not cause any short-circuiting problem in the device, instead delivering enhanced power output. Thus, the study of the charge separation/transport and electron blocking mechanism is crucial and can play a vital role in understanding the resulting physical properties and physics of the materials and device. With atomic level resolution ARM 200CF microscope equipped with the electron energy-loss spectroscopy (EELS) analysis, we can characterize more accurately the buried interface between the LSCF and SCDC further reveal the properties and distribution of charge carriers in the heterostructures. This phenomenon constrains the carrier mobility and determines the charge separation and devices' fundamental working mechanism; continued exploration of this frontier can fulfill a next generation fuel cell based on the new concept of semiconductor-ionic fuel cells (SIFCs).

  • 122602.
    Zhu, Bin
    et al.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Xia, C. R.
    Luo, X. G.
    Niklasson, G.
    Transparent two-phase composite oxide thin films with high conductivity2001Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 385, nr 02-jan, s. 209-214Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    New types of transparent thin films based on CeO2-Al2O3 and -SiO2 and ion-doped CeO2 composite oxides have been developed by sol-gel process. The films have two phases: a host phase, CeO2 or ion-doped CeO2; and a guest phase Al2O3 or SiO2, so called binary composites. This is the unique character to distinguish from other transparent films, e.g. CeO2-SnO2, -TiO2 and -ZrO2 single phase (solid solution), for electrochromic applications. Film conductivity was determined by impedance analysis and electrochemical property was investigated by cyclic voltammetry. The conductivity of the composite films is in the range of 10(-2)-0.2 S/cm in the temperature range of 500-700 degreesC. Binary films containing 30% alumina and 50% silica with thickness 35 and 30 nm have the highest amount of charge exchange for 1.0 Li/Ce and 0.7 Li/Ce, respectively. After 380 cycles the charge capacity of the CeO2-Al2O3 reached about the same value as started in the beginning. The films show a high transmittance for visible light. Unusual properties for these composite thin films have been implemented due to the special thin film nano-structure and two-phase regions and interfaces, The ionic transport and insertion/extraction mechanisms in these new composite film materials are discussed based on a proposed physical model. These composite films have a broad application in various electrochemical devices, such as electrochromic and fuel cell devices.

  • 122603.
    Zhu, Bin
    et al.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Yang, X. T.
    Xu, J.
    Zhu, Z. G.
    Ji, S. J.
    Sun, M. T.
    Sun, J. C.
    Innovative low temperature SOFCs and advanced materials2003Ingår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 118, nr 02-jan, s. 47-53Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High ionic conductivity, varying from 0.01 to 1 S cm(-1) between 300 and 700 degreesC, has been achieved for the hybrid and nano-ceriacomposite electrolyte materials, demonstrating a successful application for advanced low temperature solid oxide fuel cells (LTSOFCs). The LTSOFCs were constructed based on these new materials. The performance of 0.15-0.25 W cm(-2) was obtained in temperature region of 320400 degreesC for the ceria-carbonate composite electrolyte, and of 0.35-0.66 W cm(-2) in temperature region of 500-600 degreesC for the ceria-lanthanum oxide composites. The cell could even function at as low as 200 degreesC. The cell has also undergone a life test for several months. A two-cell stack was studied, showing expected performance successfully. The excellent LTSOFC performance is resulted from both functional electrolyte and electrode materials. The electrolytes are two phase composite materials based on the oxygen ion and proton conducting phases, or two rare-earth oxides. The electrodes used were based on the same composite material system having excellent compatibility with the electrolyte. They are highly catalytic and conductive thus creating the excellent performances at low temperatures. These innovative LT materials and LTSOFC technologies would open the door for wide applications, not only for stationary but also for mobile power sources.

  • 122604.
    Zhu, Binzhu
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk reaktionsteknik.
    Mellander, B. -E
    Fluoride-based electrolytes and their applications for intermediate temperature ceramic fuel cells2005Ingår i: Fluorinated Materials for Energy Conversion, Elsevier, 2005, s. 419-437Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    This chapter focuses on fluoride-based electrolytes and their applications for intermediate temperature ceramic fuel cells. Among all fuel cell (FC) technologies, the solid oxide fuel cell (SOFC) can utilize a number of different fuels. The conventional SOFCs use a ceramic electrolyte, e.g., yttria-stabilized zirconia (YSZ), and operate at high temperature, typically 1000°C. The high operating temperature puts very high demands on the materials and technology, which poses a major challenge for the further development of SOFCs into the market. For developing cost-effective SOFCs, much effort has been devoted to obtain a lower operating temperature. All these efforts have, however, limitations due to the deficiency of technology and the stability of the material. Ceramic fuel cells (CFCs) are sometimes used as a more general term for fuel cells based on ceramic materials, which have the desired properties. In the chapter, the focus is on possible proton and oxygen ion conduction in fluoride-based electrolytes that may be of interest for fundamental and applied research. Also, the focus is to develop new advanced CFCs for intermediate temperatures.

  • 122605.
    Zhu, Biwen
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Visual Tracking with Deep Learning: Automatic tracking of farm animals2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Automatisk spårning av övervakning i gårdens område kan bidra till att stödja jordbruket management. I detta projekt till ett automatiserat system för upptäckt upptäcka suggor från övervaknings filmer kommer att utformas med djupa lärande och datorseende metoder. Av hänsyn till Diskhantering och tid och hastighet Krav över nätverket för att uppnå realtidsscenarier i framtiden är spårning i komprimerade videoströmmar är avgörande.

    Det föreslagna systemet i detta projekt skulle använda en DCF (diskriminerande korrelationsfilter) som en klassificerare att upptäcka mål. Spårningen modell kommer att uppdateras genom att utbilda klassificeraren med online inlärningsmetoder. Compression teknik kodar videodata och minskar bithastigheter där videosignaler sänds kan hjälpa videoöverföring anpassar bättre i begränsad nätverk. det kan dock reducera bildkvaliteten på videoklipp och leder exakt hastighet av vårt spårningssystem för att minska. Därför undersöker vi utvärderingen av prestanda av befintlig visuella spårningsalgoritmer på videosekvenser Det ultimata målet med videokomprimering är att bidra till att bygga ett spårningssystem med samma prestanda men kräver färre nätverksresurser.

    Den föreslagna spårning algoritm spår framgångsrikt varje sugga i konsekutiva ramar i de flesta fall prestanda vår tracker var jämföras med två state-of-art spårning algoritmer:. Siamese Fully-Convolutional (FC) och Efficient Convolution Operators (ECO) utvärdering av prestanda Resultatet visar vår föreslagna tracker blir liknande prestanda med Siamese FC och ECO.

    I jämförelse med den ursprungliga spårningen uppnådde den föreslagna spårningen liknande spårningseffektivitet, samtidigt som det krävde mycket mindre lagring och alstra en lägre bitrate när videon komprimerades med lämpliga parametrar. Systemet är mycket långsammare än det behövs för spårning i realtid på grund av hög beräkningskomplexitet; därför behövs mer optimala metoder för att uppdatera spårningsmodellen för att uppnå realtidsspårning.

  • 122606. Zhu, Chaoyong
    et al.
    Odeberg, Jacob
    KTH, Skolan för bioteknologi (BIO), Genteknologi.
    Hamsten, Anders
    Eriksson, Per
    Allele-specific MMP-3 transcription under in vivo conditions2006Ingår i: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 348, nr 3, s. 1150-1156Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A common matrix metalloproteinases-3 (MMP-3) -1612 5A/6A promoter polymorphism is associated with risk for cardiovascular disease, rheumatoid arthritis, and other diseases. Here we used the haplotype chromatin immunoprecipitation method to study allele-specific MMP-3 expression under in vivo conditions in heterozygous THP-1 cells. Pyrosequencing was used to analyse the ratio of 5A-allele to 6A-allele after chromatin immunoprecipitation using an antibody against phosphorylated active RNA polymerase II. There was no allele-specific difference in transcriptional activity during basal conditions, i.e., in unstimulated monocytic THP-1 cells. However, after stimulation of MMP-3 expression by monocyte differentiation or incubation with IL-1 beta, the haplotype containing the 5A-allete was associated with higher transcriptional activity compared with the 6A-containing haplotype. Electromobility shift assay demonstrated increased binding of nuclear proteins to the 5A-allele after monocyte differentiation. In conclusion, the common MMP-3 5A/6A promoter polymorphism appears to be functional only during specific environmental conditions involving inflammation.

  • 122607.
    Zhu, Di
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Large Scale ETL Design, Optimization and Implementation Based On Spark and AWS Platform2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Mängden data som genereras internet-produkt-användare ökar lavinartat och exponentiellt. Det finns otaliga exempel på detta; klick-strömmen från hemsidor med miljontals användare, geospatial information från GISbaserade Android och iPhone appar, eller från sensorer på autonoma bilar.Mängden händelser från de här typerna av data kan enkelt uppnå miljardantal dagligen, därför är det föga förvånande att det är möjligt att extrahera insikter från de här data-strömmarna. Till exempel kan man sätta upp automatiserade övervakningssystem eller kalibrera bedrägerimodeller effektivt. Att handskas med data i de här storleksordningarna är dock inte helt problemfritt, det finns flertalet tekniska bekymmer som enkelt kan uppstå. Datan är inte alltid på samma form, den kan vara av olika dimensioner vilket gör det betydligt svårare att designa en effektiv data-pipeline, transformera datan och lagra den persistent i ett data-warehouse. Onekligen finns det traditionella sätt att bygga ETL’s på från mainframe [1], RDBMS, till MapReduce och Hive. Dock har det med upptäckten och ökade populariteten av Spark och AWS blivit mer robust, effektivt, billigare och enklare att implementera system för att samla data, bygga dimensions-enliga modeller och genomföra analys av massiva data-set. Den här uppsatsen bidrar till en ökad förståelse kring hur man bygger och optimerar ETL-pipelines baserade på AWS och Spark och jämför med huvudsakliga nuvarande Data-pipelines med hänsyn till diverse aspekter. Uppsatsen drar nytta av att ha tillgång till ett massivt data-set med miljarder användar-events genererade dagligen från ett bil-transport-bolag i mellanöstern.

  • 122608.
    Zhu, Fei
    et al.
    Univ Edinburgh, Genes Cognit Program, Ctr Clin Brain Sci, Edinburgh EH16 4SB, Midlothian, Scotland.;UCL Inst Neurol, Queen Sq, London WC1N 3BG, England..
    Cizeron, Melissa
    Univ Edinburgh, Genes Cognit Program, Ctr Clin Brain Sci, Edinburgh EH16 4SB, Midlothian, Scotland.;Univ Claude Bernard Lyon 1, Univ Lyon, Inst NeuroMyoGene, CNRS,UMR 5310,INSERM,U1217, F-69008 Lyon, France..
    Qiu, Zhen
    Univ Edinburgh, Genes Cognit Program, Ctr Clin Brain Sci, Edinburgh EH16 4SB, Midlothian, Scotland..
    Benavides-Piccione, Ruth
    CSIC, Inst Cajal, E-28002 Madrid, Spain.;UPM, Ctr Tecnol Biomed, Madrid 28223, Spain.;ISCIII, CIBERNED, Madrid 28031, Spain..
    Kopanitsa, Maksym V.
    Synome Ltd, Babraham Res Campus, Cambridge CB22 3AT, England.;Imperial Coll London, UK Dementia Res Inst, London W12 0NN, England..
    Skene, Nathan G.
    Univ Edinburgh, Genes Cognit Program, Ctr Clin Brain Sci, Edinburgh EH16 4SB, Midlothian, Scotland.;UCL Inst Neurol, Queen Sq, London WC1N 3BG, England.;Karolinska Inst, Dept Med Biochem & Biophys, Lab Mol Neurobiol, S-17177 Stockholm, Sweden..
    Koniaris, Babis
    Univ Edinburgh, Genes Cognit Program, Ctr Clin Brain Sci, Edinburgh EH16 4SB, Midlothian, Scotland..
    DeFelipe, Javier
    CSIC, Inst Cajal, E-28002 Madrid, Spain.;UPM, Ctr Tecnol Biomed, Madrid 28223, Spain.;ISCIII, CIBERNED, Madrid 28031, Spain..
    Fransén, Erik
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Beräkningsvetenskap och beräkningsteknik (CST).
    Komiyama, Noboru H.
    Univ Edinburgh, Genes Cognit Program, Ctr Clin Brain Sci, Edinburgh EH16 4SB, Midlothian, Scotland..
    Grant, Seth G. N.
    Univ Edinburgh, Genes Cognit Program, Ctr Clin Brain Sci, Edinburgh EH16 4SB, Midlothian, Scotland..
    Architecture of the Mouse Brain Synaptome2018Ingår i: Neuron, ISSN 0896-6273, E-ISSN 1097-4199, Vol. 99, nr 4, s. 781-+Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Synapses are found in vast numbers in the brain and contain complex proteomes. We developed genetic labeling and imaging methods to examine synaptic proteins in individual excitatory synapses across all regions of the mouse brain. Synapse catalogs were generated from the molecular and morphological features of a billion synapses. Each synapse subtype showed a unique anatomical distribution, and each brain region showed a distinct signature of synapse subtypes. Whole-brain synaptome cartography revealed spatial architecture from dendritic to global systems levels and previously unknown anatomical features. Synaptome mapping of circuits showed correspondence between synapse diversity and structural and functional connectomes. Behaviorally relevant patterns of neuronal activity trigger spatio-temporal postsynaptic responses sensitive to the structure of synaptome maps. Areas controlling higher cognitive function contain the greatest synapse diversity, and mutations causing cognitive disorders reorganized synaptome maps. Synaptome technology and resources have wide-ranging application in studies of the normal and diseased brain.

  • 122609.
    Zhu, Feng
    KTH, Tidigare Institutioner                               , Materialvetenskap.
    Atmospheric corrosion of precoated steel in a confined environment2000Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 122610. Zhu, Feng
    et al.
    Li, Cuiping
    Ha, Minh Ngoc
    Liu, Zhifu
    Guo, Qiangsheng
    Zhao, Zhe
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Shanghai Inst Technology, China.
    Molten-salt synthesis of Cu-SrTiO3/TiO2 nanotube heterostructures for photocatalytic water splitting2016Ingår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 51, nr 9, s. 4639-4649Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of Cu-loaded SrTiO3/TiO2 nanotube heterostructures were synthesized by a facile molten salts method and an impregnation-calcination method. Through adjusting the molar ratio of Sr/Ti, the photocatalytic performance of the samples changed regularly. When Sr/Ti = 0.2, the catalyst showed the highest performance in water splitting and the H-2 generation amount was 0.597 mmol under UV irradiation for 8 h. The enhanced performance of Cu-loaded SrTiO3/TiO2 nanotubes could be attributed to the heterostructures, the small crystallite size, and the reduced band gap inside them.

  • 122611. Zhu, H.
    et al.
    Cai, T.
    Xu, J.
    Wu, S.
    Li, X.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. South China Normal University (SCNU), China.
    Neural correlates of stereoscopic depth perception: A fNIRS study2016Ingår i: 2016 Progress In Electromagnetics Research Symposium, PIERS 2016 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2016, s. 4442-4446, artikel-id 7735646Konferensbidrag (Refereegranskat)
    Abstract [en]

    The aim of the present study was to explore the brain region correlated with stereoscopic depth perception with different degree of binocular disparities. fNIRS was used to measure the neural activity of the occipital cortex induced by random-dot stereogram (RDS) with disparities from 0.1° to 1.5° and analyzed the strength and activation pattern from participants with left and right eyedness. Results revealed that the visual cortex was spatial correlated with the binocular disparity and there was a left lateralization effect for right-eye-dominant participants. Furthermore, binocular disparity around 0.5° led the strongest activation, whereas binocular disparity exceed 1.1° led lower activation which could be caused by visual fatigue. The present study supported the feasibility of fNIRS to assess the neural correlates of stereoscopic depth perception, to optimize the stereoscopic vision, and to objective evaluation of visual fatigue.

  • 122612. Zhu, H.
    et al.
    Fan, Y.
    Li, X.
    Huang, D.
    Guo, H.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Some effects of specific interest on the brain of children with autism spectrum disorder (ASD): A functional near-infrared spectroscopy study2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Autism spectrum disorder (ASD) is a neuro-developmental disorder, characterized by two major domains: impairments in the social cognition and communication as well as restricted, repetitive, stereotyped interests and behaviors. In this study, functional near-infrared spectroscopy (fNIRS) was applied to investigate the atypical activation pattern of language areas (bilateral inferior frontal gyrus and bilateral temporal cortex) and uncover the impact of a specific interest on the brain function of children with ASD. We employed a listening comprehension task to stimulate the language areas of 2 ASD boys (A1 and A2) who had strong interests in the experiment material ("Lightning McQueen") and another 2 ASD boys (A3 and A4) who were matched with A1 and A2 respectively by age, intelligence quotient, language ability and the severity of symptoms. Our results showed that, during the task, the picture of "Lightning McQueen", but not the words of "The little red car", elicited stronger activation in the bilateral inferior frontal gyrus and temporal cortex of A1 and A2 than A3 and A4. These results could facilitate our understanding of language development of ASD and reconsider the role of specific interests (especially visual stimuli) played in the brain functional development of ASD.

  • 122613. Zhu, H. J.
    et al.
    Wang, M.
    Jin, K.
    Dai, D.
    Sun, Licheng C.
    Chen, C. N.
    Coordination polyhedra of eight-coordinate zirconium complexes and a network built up by crisscross Cl...Cl contacts2005Ingår i: Transition metal chemistry (Weinheim), ISSN 0340-4285, E-ISSN 1572-901X, Vol. 30, nr 5, s. 517-522Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two bis(quadridentate) eight-coordinate zirconium complexes, Zr(5-Cldse)(2) (1) [5-Cldse = N,N'-di(5-chlorosalicylidene)ethylenediamino] and Zr(pida)(2) (2) [pida = N-(2-pyridylmethyl) iminodiacetato], have been prepared and crystallographically characterized. A distorted dodecahedron of N4O4 atoms has been found for the zirconium(IV) center of complexes (1) and (2). A network is constructed in the crystalline state of (1) by crisscross intermolecular Cl...Cl contacts (3.45 and 3.43 angstrom), which are shorter than the sum of spherical van der Waals radii (3.50 angstrom).

  • 122614. Zhu, H. J.
    et al.
    Wang, M.
    Ma, C. B.
    Li, B.
    Chen, C. N.
    Sun, Licheng C.
    Preparation and structures of 6-and 7-coordinate salen-type zirconium complexes and their catalytic properties for oligomerization of ethylene2005Ingår i: Journal of Organometallic Chemistry, ISSN 0022-328X, E-ISSN 1872-8561, Vol. 690, nr 17, s. 3929-3936Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of salen-type zirconium complexes of the general formula LZrCl2 (L = N,N '-ethylenebis(salicylideneiminate), 3a; N,N '-ethylenebis(3,5-di-tert -butylsalicylideneiminate), 3b; N,N '-ethylenebis(5-methoxysalicylidenciminate), 3e; N,N '-o-phethylenebis(5-chlorosalicylideneiminate), 3d; N,N '-ethylenebis(5-nitrosalicylideneiminate), 3e; N,N '-o-phenylenebis(salicylideneiminate), 4a; N,N '-o-phenylenebis(3,5-di-tert-butylsalicylideneiminate), 4b; N,N '-o-phenylenebis(5-methoxysalicylideneiminate), 4c; N,N '-o-phenylenebis(5-chloro-salicylideneiminate), 4d) were prepared. The crystal structures of 6- and 7-coordinate zirconium complexes 4b and [4b center dot OCMe2] were determined by X-ray crystallography, which reveals that a salen-type zirconium complex possesses a labile coordination site on the Zr center with a relatively stable framework and that the coordination and the dissociation of O-donor molecules occur readily at this site. The catalytic properties of 3(a-e) and 4(a-d) were studied for ethylene oligomerization in combination with Et2AlCl as co-catalyst. Complex 3c featuring a methoxy-substituted salen ligand displayed higher activity than its analogous precursors having chloro and nitro groups as substituents. The catalytic reactions by 3(a-e) and 4(a-d) gave C-4-C-10 olefins and low-carbon linear (alpha-olefins in good selectivity.

  • 122615. Zhu, H. Y.
    et al.
    Li, J.
    Shen, J. Q.
    He, Sailing
    Localization of current dipoles in a realistic head shape model by a magnetoencephalogram-multiple signal classification algorithm2003Ingår i: Wuli xuebao, ISSN 1000-3290, Vol. 52, nr 7, s. 1812-1817Artikel i tidskrift (Refereegranskat)
  • 122616. Zhu, Haibo
    et al.
    Li, Wenqin
    Wu, Yongzhen
    Liu, Bo
    Zhu, Shiqin
    Li, Xin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Zhu, Weihong
    Insight into Benzothiadiazole Acceptor in D-A-pi-A Configuration on Photovoltaic Performances of Dye-Sensitized Solar Cells2014Ingår i: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 2, nr 4, s. 1026-1034Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The option of conjugated pi-linkers is critical for molecular engineering toward the energy-level strategy of donor-pi-acceptor (D-pi-A) sensitizers. There is always a balance in the optimization of a it-linker. The pi-conjugation should be enlarged to expand the light-harvesting capability of sensitizers for an increase in photocurrent; however, the oversized it-linker also would affect seriously the photovoltage and photostability. Two sensitizers, WS-22 and WS-23, are constructed without or with benzothiadiazole (BTD) in a molecular skeleton, aiming to gain insight into the effect of an auxiliary acceptor in D-A-pi-A sensitizers on the photophysical and photovoltaic performances, especially focusing on the exploitation of the short circuit current density (J(sc)) and open circuit voltage (V-oc). Compared with the typical D-pi-A sensitizer WS-22, the incorporation of an auxiliary acceptor of BTD in WS-23 can improve the light-harvesting ability both in red-shifting the absorption peaks and the increment of absorption coefficient. The predominant increase by 15.6% in light-harvesting efficiency (LHE) of WS-23 results in a relatively higher J(sc) from 13.77 (WS-22) to 16.91 mA cm(-2) (WS-23). Moreover, the improvement of the V-oc in WS-23 is originated by a synergy contribution of the uplifting of E-CB and inhibition of charge recombination. The stepped light-induced transient (SLIT) measurements indicate that the introduction of BTD can negatively shift the conduction band of the TiO2 film. For WS-23, the higher molecular dipole moment can bring forth a more effective charge separation between donor and acceptor units, also resulting in an increase in V-oc. The incorporated BTD unit can increase V-oc by 57 mV, arising from the CB edge shift of TiO2 (accounting for 40%, 23 mV) and the retarding charge recombination (accounting for 60%, 34 mV). As a consequence, WS-23 realizes an optimizing photovoltaic efficiency (eta = 8.15%), with an improvement of 36.5% with respect to WS-22.

  • 122617. Zhu, Hongjun
    et al.
    Hagfeldt, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Boschloo, Gerrit
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Photoelectrochemistry of mesoporous NiO electrodes in Iodide/Triiodide electrolytes2007Ingår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 111, nr 47, s. 17455-17458Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mesoporous NiO electrodes were used in photoelectrochemical cells using iodide/triiodide-based redox electrolytes. Cathodic photocurrents were found upon visible light excitation. These photocurrents were enhanced when coumarin 343 dye was adsorbed at the NiO surface or when a unanchored dye (coumarin 337) was added to the electrolyte. The proposed reaction for photocurrent generation is as follows: in the absence of dyes, excitation of triiodide leads to the generation of diiodide radicals, which subsequently accept electrons from the NiO electrode. Enhanced photocurrent generation in the presence of dyes is possibly due to energy transfer from excited dye molecules to triiodide. Charge transport studies of C343-sensitized NiO suggest that hole transport in mesoporous NiO is due to hopping of positive charge between Ni-surface atoms.

  • 122618.
    Zhu, Hongli
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Areskogh, Dimitri
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Helander, Mikaela
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    A preliminary investigation on enzymatic oxidative polymerization of lignin2011Ingår i: 16th International Symposium on Wood, Fiber and Pulping Chemistry: Proceedings, ISWFPC, 2011, s. 238-241Konferensbidrag (Refereegranskat)
    Abstract [en]

    Enzyme catalyzed oxidative polymerization of technical bagasse lignin and low-molecular-weight ultra-filtered kraft pulp lignin (UFL) were studied in methanol-water solution. Lignin was dissolved in methanol-water solution at pH 13 in steam heated autoclave at 130°C for 2h. The polymerization reaction was conducted at 40°C with a commercial laccase under oxygen saturation. The weight-average molecular weight (Mw) of original macromonomer and polymerized lignin were characterized with alkaline size exclusion Chromatograph (SEC) system. Enzyme treatment increased the molecular weight of both technical bagasse lignin and ultra-filtered lignin up to 20 times. The reaction time and the enzyme dosage were studied to obtain the maximal molecular weight.

  • 122619.
    Zhu, Hongli
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Areskogh, Dimitri
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Helander, Mikaela
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Investigation on enzymatic oxidative polymerization of technical soda lignin2012Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 243Artikel i tidskrift (Övrigt vetenskapligt)
  • 122620.
    Zhu, Hongli
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Areskogh, Dimitri
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Helander, Mikaela
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Investigation on enzymatic oxidative polymerization of technical soda lignin2012Ingår i: Current organic chemistry, ISSN 1385-2728, E-ISSN 1875-5348, Vol. 16, nr 16, s. 1850-1854Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Enzyme, including laccase and peroxidase, catalyzed oxidative polymerization of technical bagasse soda lignin and low molecular weight ultra-filtrated kraft pulp lignin in methanol-water solution were studied. The weight average molecular weight of original macromonomer and polymerized lignin were characterized with alkaline size exclusion chromatograph system. Laccase treatment increased the molecular weight of both technical bagasse lignin and ultra-filtrated lignin up to 20 times in 24h. Compared to the low molecular weight ultra filtrated lignin, the reaction rate of bagasse lignin was consistant during the whole procedure. The reaction time and the laccase dosage were investigated to obtain the maximal molecular weight. The horseradish peroxidase treatment was a potential method for low molecular weight ultra filtrated lignin.

  • 122621.
    Zhu, Hongli
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Helander, Mikaela
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Moser, Carl
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Ståhlkranz, Adam
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Lindström, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    A novel nano cellulose preparation method and size fraction by cross flow ultra- filtration2012Ingår i: Current organic chemistry, ISSN 1385-2728, E-ISSN 1875-5348, Vol. 16, nr 16, s. 1871-1875Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel energy-efficient method called nanopulping (patent pending) to produce nanocellulose from chemical pulp, and a novel cross-flow ultra-filtration method to separate nanofibrils fractions of different size were applied in this study. Pretreatment with endoglucanase or 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidation seems to enhance the nanopulping process. Results were evaluated with atomic force microscope and ultrafiltration. The nanopulping produced a relatively inhomogeneous material with larger particles/ fibers in addition to nanofibers. However, by ultrafiltration of the material it was possible to obtain more homogeneous material in different dimensions with methods industrially acceptable.

  • 122622.
    Zhu, Hongli
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Li, Yuanyuan
    Pettersson, Bert
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Zhang, Liming
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Lindström, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Technical soda lignin dissolved in urea as an environmental friendly binder in wood fiberboard2014Ingår i: Journal of Adhesion Science and Technology, ISSN 0169-4243, E-ISSN 1568-5616, Vol. 28, nr 5, s. 490-498Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The application of lignin as binder in wood composite panel is not only environmentally friendly but also commercially attractive. The dissolving of technical soda lignin is the most premier challenge in its application. In this study, the effect of different key factors on soda lignin solubility in urea was investigated. The maximum solubility of 60.16g/L was obtained under the temperature 70 degrees C, urea concentration 8M, lignin content 7%, and pH 8.8. Then, different kinds of wood fiber material were mixed with the dissolved lignin solution to make fiber board separately. The results showed that the lignin can enhance the tensile strength of particleboard and can be used as a binder in wood material, but the strength will be different with different materials. The optimal tensile strength obtained was 44.63MPa with the sample made from oriented cotton linter sheet.

  • 122623. Zhu, Hongli
    et al.
    Luo, Wei
    Ciesielski, Peter N.
    Fang, Zhiqiang
    Zhu, J. Y.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Himmel, Michael E.
    Hu, Liangbing
    Wood-Derived Materials for Green Electronics, Biological Devices, and Energy Applications2016Ingår i: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 116, nr 16, s. 9305-9374Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    With the arising of global climate change and resource shortage, in recent years, increased attention has been paid to environmentally friendly materials. Trees are sustainable and renewable materials, which give us shelter and oxygen and remove carbon dioxide from the atmosphere. Trees are a primary resource that human society depends upon every day, for example, homes, heating, furniture, and aircraft. Wood from trees gives us paper, cardboard, and medical supplies, thus impacting our homes, school, work, and play. All of the above-mentioned applications have been well developed over the past thousands of years. However, trees and wood have much more to offer us as advanced materials, impacting emerging high-tech fields, such as bioengineering, flexible electronics, and clean energy. Wood naturally has a hierarchical structure, composed of well-oriented microfibers and tracheids for water, ion, and oxygen transportation during metabolism. At higher magnification, the walls of fiber cells have an interesting morphology-a distinctly mesoporous structure. Moreover, the walls of fiber cells are composed of thousands of fibers (or macrofibrils) oriented in a similar angle. Nanofibrils and nanocrystals can be further liberated from macrofibrils by mechanical, chemical, and enzymatic methods. The obtained nanocellulose has unique optical, mechanical, and barrier properties and is an excellent candidate for chemical modification and reconfiguration. Wood is naturally a composite material, comprised of cellulose, hemicellulose, and lignin. Wood is sustainable, earth abundant, strong, biodegradable, biocompatible, and chemically accessible for modification; more importantly, multiscale natural fibers from wood have unique optical properties applicable to different kinds of optoelectronics and photonic devices. Today, the materials derived from wood are ready to be explored for applications in new technology areas, such as electronics, biomedical devices, and energy. The goal of this study is to review the fundamental structures and chemistries of wood and wood-derived materials, which are essential for a wide range of existing and new enabling technologies. The scope of the review covers multiscale materials and assemblies of cellulose, hemicellulose, and lignin as well as other biomaterials derived from wood, in regard to their major emerging applications. Structure properties application relationships will be investigated in detail. Understanding the fundamental properties of these structures is crucial for designing and manufacturing products for emerging applications. Today, a more holistic understanding of the interplay between the structure, chemistry, and performance of wood and wood-derived materials is advancing historical applications of these materials. This new level of understanding also enables a myriad of new and exciting applications, which motivate this review. There are excellent reviews already on the classical topic of woody materials, and some recent reviews also cover new understanding of these materials as well as potential applications. This review will focus on the uniqueness of woody materials for three critical applications: green electronics, biological devices, and energy storage and bioenergy.

  • 122624.
    Zhu, Hui
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Design of Optimal Energy Flow Control with Privacy-Cost Trade-Off in Smart Grids2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Inom ett potentiellt område, har utvecklingen av smarta elnät dragit mer och mer uppmärksamhet från många länder. En smart elmätare spelar en signifikant roll i ett smart elnät. Den ersätter den traditionella elmätaren med förmågan att ofta överföra den momentana energiförbrukning som konsumenten mottar av energileverantören av smarta elnät. Från elleverantörens sida, är det fördelaktigt för planering, styrning och fakturering. Men från konsumenternas perspektiv kan den högupplösta energiförbrukningen leda till integritetsproblem, vilket innebär att konsumenternas beteende kan avslöjas genom att analysera de smarta mätaravläsningarna. I detta projekt kommer vi fokusera på integritetsproblemen som dessa mätare ger upphov till. Vi studerar problemet med att balansera integritetsproblemeti ett smart elnät bestående av en energileverantör, en alternativ energikälla, ensmart mätare, och en energistyrenhet. Den personliga integriteten äventyras dåen obehörig kan få tillgång till konsumentens beteende baserat på de smartamätvärdena av energiförbrukningen från energileverantören. Kontrollstrateginär utformad för att hantera energiinflödet för att tillfredsställa de momentanaenergibehov konsumenten har, och även för att optimalt avväga privatlivs riskoch energikostnader. För att utvärdera den personliga integriteten risk, an-vänder vi en Bayesiansk upptäckt dvs. operativ integritets uträkning. Olikascenarier beaktas och deras optimeringsproblem kan reduceras till linjära pro-grammeringar. Baserat på observationen är motsvarande kontrollstrategi meddesignade algoritmer att föredra.

  • 122625. Zhu, Huilin
    et al.
    Fan, Yuebo
    Guo, Huan
    Huang, Dan
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Reduced interhemispheric functional connectivity of children with autism spectrum disorder: evidence from functional near infrared spectroscopy studies2014Ingår i: Biomedical Optics Express, ISSN 2156-7085, E-ISSN 2156-7085, Vol. 5, nr 4, s. 1262-1274Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Autism spectrum disorder (ASD) is a neuro-developmental disorder, which has been associated with atypical neural synchronization. In this study, functional near infrared spectroscopy (fNIRS) was used to study the differences in functional connectivity in bilateral inferior frontal cortices (IFC) and bilateral temporal cortices (TC) between ASD and typically developing (TD) children between 8 and 11 years of age. As the first report of fNIRS study on the resting state functional connectivity (RSFC) in children with ASD, ten children with ASD and ten TD children were recruited in this study for 8 minute resting state measurement. Compared to TD children, children with ASD showed reduced interhemispheric connectivity in TC. Children with ASD also showed significantly lower local connectivity in bilateral temporal cortices. In contrast to TD children, children with ASD did not show typical patterns of symmetry in functional connectivity in temporal cortex. These results support the feasibility of using the fNIRS method to assess atypical functional connectivity of cortical responses of ASD and its potential application in diagnosis.

  • 122626. Zhu, Huilin
    et al.
    Li, Jun
    Fan, Yuebo
    Li, Xinge
    Huang, Dan
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Atypical prefrontal cortical responses to joint/non-joint attention in children with autism spectrum disorder (ASD): A functional near-infrared spectroscopy study2015Ingår i: Biomedical Optics Express, ISSN 2156-7085, E-ISSN 2156-7085, Vol. 6, nr 3, s. 690-701Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Autism spectrum disorder (ASD) is a neuro-developmental disorder, characterized by impairments in one's capacity for joint attention. In this study, functional near-infrared spectroscopy (fNIRS) was applied to study the differences in activation and functional connectivity in the prefrontal cortex between children with autism spectrum disorder (ASD) and typically developing (TD) children. 21 ASD and 20 TD children were recruited to perform joint and non-joint attention tasks. Compared with TD children, children with ASD showed reduced activation and atypical functional connectivity pattern in the prefrontal cortex during joint attention. The atypical development of left prefrontal cortex might play an important role in social cognition defects of children with ASD.

  • 122627.
    Zhu, J.
    et al.
    Peking University.
    Qi, Chong
    Peking University.
    Liu, Meng
    Cui, X.
    Xu, F.
    Shape transitions in proton-rich Ho and Tm isotopes2009Ingår i: Chinese Physics C, High Energy Physics & Nuclear Physics, ISSN 1674-1137, E-ISSN 0899-9996, Vol. 33, s. 9-11Artikel i tidskrift (Refereegranskat)
  • 122628. Zhu, J
    et al.
    Zhao, C
    Kharman-Biz, A
    Zhuang, T
    Jonsson, P
    Liang, N
    Williams, Cecilia
    University of Houston, United States .
    Lin, C-Y
    Qiao, Y
    Zendehdel, K
    Strömblad, S
    Treuter, E
    Dahlman-Wright, K
    The atypical ubiquitin ligase RNF31 stabilizes estrogen receptor α and modulates estrogen-stimulated breast cancer cell proliferation.2014Ingår i: Oncogene, ISSN 0950-9232, E-ISSN 1476-5594, Vol. 33, nr 34, s. 4340-4351Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Estrogen receptor α (ERα) is initially expressed in the majority of breast cancers and promotes estrogen-dependent cancer progression by regulating the transcription of genes linked to cell proliferation. ERα status is of clinical importance, as ERα-positive breast cancers can be successfully treated by adjuvant therapy with antiestrogens or aromatase inhibitors. Complications arise from the frequent development of drug resistance that might be caused by multiple alterations, including components of ERα signaling, during tumor progression and metastasis. Therefore, insights into the molecular mechanisms that control ERα expression and stability are of utmost importance to improve breast cancer diagnostics and therapeutics. Here we report that the atypical E3 ubiquitin ligase RNF31 stabilizes ERα and facilitates ERα-stimulated proliferation in breast cancer cell lines. We show that depletion of RNF31 decreases the number of cells in the S phase and reduces the levels of ERα and its downstream target genes, including cyclin D1 and c-myc. Analysis of data from clinical samples confirms correlation between RNF31 expression and the expression of ERα target genes. Immunoprecipitation indicates that RNF31 associates with ERα and increases its stability and mono-ubiquitination, dependent on the ubiquitin ligase activity of RNF31. Our data suggest that association of RNF31 and ERα occurs mainly in the cytosol, consistent with the lack of RNF31 recruitment to ERα-occupied promoters. In conclusion, our study establishes a non-genomic mechanism by which RNF31 via stabilizing ERα levels controls the transcription of estrogen-dependent genes linked to breast cancer cell proliferation.

  • 122629. Zhu, J.
    et al.
    Zhao, C.
    Zhuang, T.
    Jonsson, P.
    Sinha, I.
    Williams, Cecilia
    KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Strömblad, S.
    Dahlman-Wright, K.
    RING finger protein 31 promotes p53 degradation in breast cancer cells2016Ingår i: Oncogene, ISSN 0950-9232, E-ISSN 1476-5594, Vol. 35, nr 15, s. 1955-1964Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The atypical E3 ubiquitin ligase RNF31 is highly expressed in human breast cancer, the most frequent neoplastic lethality among women. Here, RNF31 depletion in breast cancer cells in combination with global gene expression profiling revealed p53 (TP53) signaling as a potential RNF31 target. Interestingly, RNF31 decreased p53 stability, whereas depletion of RNF31 in breast cancer cells caused cell cycle arrest and cisplatin-induced apoptosis in a p53-dependent manner. Furthermore, RNF31 associated with the p53/MDM2 complex and facilitated p53 polyubiquitination and degradation by stabilizing MDM2, suggesting a molecular mechanism by which RNF31 regulates cell death. Analysis of publically available clinical data sets displayed a negative correlation between RNF31 and p53 target genes, including IGFBP3 and BTG1, consistent with RNF31 regulating p53 function in vivo as well. Together, our findings suggest RNF31 as a potential therapeutic target to restore p53 function in breast cancer.

  • 122630.
    Zhu, Jiahua
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Study on Sensors for Environment Monitoring2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Nowadays, the role water quality played has become more and more important, especially in the industrial field, which can directly impact the cost and quality of the products. Similarly, the quality of wastewater directly impacts the efficiency of the reuse and discharge of wastewater. To monitor the parameters during the process of waste water treatment, an exited Wireless Sensor Network service is proposed. The object of this article is to investigate the methods of wireless sensor on the main nods of the WSN system.

    The set of water quality standards is depended on the different requirements in different specials. This article was concerned about PH, dissolved oxygen, turbidity and chlorine which are the key parameters of water quality for industrial. Generally, there are two ways to measure the indicators, electrochemical and optical. In this article, the investigation is based on these two ways.

    The most suitable way to sense the PH value is using PH sensitive electrode. Two ways to monitor the dissolved oxygen, optical methods and electrode method, are introduced and compared. This thesis also introduced how to measure the turbidity with optical components. Two most common principals for chlorine are introduced and compared; one is called DPD colorimetric detection which is based on N, N-Diethyl-p-Phenylenediamine (DPD) reaction with active halogens, the other is called Amperometry which is en electrochemical technique that measures the change in current resulting from chemical reactions taking place as a function of the analytic concentration.

    Based on the principals introduced above, two experiments are proposed. One is for the PH measurement. The test circumstance consists of a relatively inexpensive PH electrode, a voltmeter and a reference PH meter. The other one is for the turbidity measurement which consists of two LEDs and a light-to-voltage sensor.

  • 122631. Zhu, Jianfei
    et al.
    Jiang, Wei
    Liu, Yichao
    Yin, Ge
    Yuan, Jun
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. Zhejiang University, China; South China Normal University, China.
    Ma, Yungui
    Three-dimensional magnetic cloak working from d.c. to 250 kHz2015Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, artikel-id 8931Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Invisible cloaking is one of the major outcomes of the metamaterial research, but the practical potential, in particular for high frequencies (for example, microwave to visible light), is fatally challenged by the complex material properties they usually demand. On the other hand, it will be advantageous and also technologically instrumental to design cloaking devices for applications at low frequencies where electromagnetic components are favourably uncoupled. In this work, we vastly develop the bilayer approach to create a three-dimensional magnetic cloak able to work in both static and dynamic fields. Under the quasi-static approximation, we demonstrate a perfect magnetic cloaking device with a large frequency band from 0 to 250 kHz. The practical potential of our device is experimentally verified by using a commercial metal detector, which may lead us to having a real cloaking application where the dynamic magnetic field can be manipulated in desired ways.

  • 122632. Zhu, Jian-Xin
    et al.
    Janoschek, Marc
    Chaves, D. S.
    Cezar, J. C.
    Durakiewicz, Tomasz
    Ronning, Filip
    Sassa, Yasmine
    Månsson, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Scott, B. L.
    Wakeham, N.
    Bauer, Eric D.
    Thompson, J. D.
    Electronic correlation and magnetism in the ferromagnetic metal Fe3GeTe22016Ingår i: PHYSICAL REVIEW B, ISSN 2469-9950, Vol. 93, nr 14, artikel-id 144404Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Motivated by the search for design principles of rare-earth-free strong magnets, we present a study of electronic structure and magnetic properties of the ferromagnetic metal Fe3GeTe2 within the local-density approximation (LDA) of the density-functional theory, and its combination with dynamical mean-field theory (DMFT). To compare these calculations, we measure magnetic and thermodynamic properties as well as x-ray magnetic circular dichroism and the photoemission spectrum of single-crystal Fe3GeTe2. We find that the experimentally determined Sommerfeld coefficient is enhanced by an order of magnitude with respect to the LDA value. This enhancement can be partially explained by LDA+DMFT. In addition, the inclusion of dynamical electronic correlation effects provides the experimentally observed magnetic moments, and the spectral density is in better agreement with photoemission data. These results establish the importance of electronic correlations in this ferromagnet.

  • 122633.
    Zhu, Jinchao
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Computational Weld Mechanics - estimation of angular distortion and residual stresses2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The present study estimates the angular distortion and the residual stresses using the following methodologies: Thermo-elastic-plastic, Inherent strain (local-global) and Substructuring on two types of welded joints: T-type fillet weld and butt weld. The numerical results are compared with the experimental measurements and these methodologies are evaluated in terms of accuracy and computational time. The influence of welding sequence towards distortion and transverse residual stresses has been studied numerically by implementing Thermo-elastic-plastic and Inherent strain (local-global) methods on T-type fillet weld. It shows that the welding position and welding direction have almost the same influence on angular distortions from Thermo-elastic-plastic method. The Inherent strain (local-global) method can estimate the angular distortion caused by different weld position in good agreement with Thermo-elastic-plastic method. To have a better understanding of where the underestimation of angular distortion in Inherent strain (local-global) method comes from, the study discusses the influence of block length and welding speed towards angular distortion. It is found that for long weld length or slow welding speed, activating the plastic strain gradually by dividing the weld bead into an appropriate number of blocks can reduce the level of underestimation of angular distortion.

  • 122634. Zhu, Jing
    et al.
    Deng, Hui
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Dong, Wenjing
    Zhang, Wei
    Li, Junjiao
    Bao, Xujin
    Polymer-assistant ceramic nanocomposite materials for advanced fuel cell technologies2017Ingår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 43, nr 7, s. 5484-5489Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, nanocomposites of LaCePr-oxide (LCP) and Ni0.8Co0.15Al0 05LIO2-delta (NCAL) with different contents of polyvinylidene fluoride (PVDF) were prepared and applied to solid oxide fuel cells. The composite materials were characterized by X-ray diffraction analysis (XRD), scanning electron microscope (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and electrochemical impedance spectrum (EIS). The effect of PVDF concentration on the conductivity and performance of the fuel cells was investigated. It was found that PVDF plays a template role of pore forming in the nanocomposites, and the changed microstructure by as-formed pores greatly influences the electrochemical property of the nanocomposites. The cell with 3 wt% PVDF heat-treated at 210 C-omicron achieved the highest power density of 982 mW cm(-2) at 520 C-omicron, which enhanced performance by more than 57% than when no heat-treatment was implemented. It is 66% higher than the cell with no PVDF and no heat-treatment. Pores formed by PVDF after heat-treatment enlarged the triple phase boundary (TPB), which results in improved fuel cell performance.

  • 122635.
    Zhu, Jing
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab). Univ Sci & Technol China, Sch Informat Sci & Technol, Hefei, Anhui, Peoples R China..
    Natalino, Carlos
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Furdek, Marija
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Zhu, Zuqing
    Univ Sci & Technol China, Sch Informat Sci & Technol, Hefei, Anhui, Peoples R China..
    Control Plane Robustness in Software-Defined Optical Networks under Targeted Fiber Cuts2018Ingår i: 22ND INTERNATIONAL CONFERENCE ON OPTICAL NETWORK DESIGN AND MODELING (ONDM 2018) / [ed] Ruffini, M Tzanakaki, A Casellas, R Autenrieth, A MarquezBarja, JM, IEEE , 2018, s. 118-123Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Software-Defined Optical Networking (SDON) paradigm enables programmable, adaptive and application-aware backbone networks. However, aside from the manifold advantages, the centralized Network Control and Management in SDONs also gives rise to a number of security concerns at different network layers. As communication between the control and the data plane devices in an SDON utilizes the common optical fiber infrastructure, it can be subject to various targeted attacks aimed at disabling the underlying optical network infrastructure and disrupting the services running in the network. In this work, we focus on the threats from targeted fiber cuts to the control plane (CP) robustness in an SDON under different link cut attack scenarios with diverse damaging potential, modeled through a newly defined link criticality measure based on the routing of control paths. To quantify the robustness of a particular CP realization, we propose a metric called Average Control Plane Connectivity (ACPC) and analyze the CP robustness for a varying number of controller instances in master/slave configuration. Simulation results indicate that CP enhancements in terms of controller addition do not necessarily yield linear improvements in CP robustness but require tailored CP design strategies.

  • 122636. Zhu, Jing-Jing
    et al.
    Zhang, A. Ping
    Xia, Tian-Hao
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Xue, Wei
    Fiber-Optic High-Temperature Sensor Based on Thin-Core Fiber Modal Interferometer2010Ingår i: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 10, nr 9, s. 1415-1418Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a new fiber-optic high-temperature sensor based on a thin-core fiber (TCF) modal interferometer. A thin-core fiber, whose core radius is about half of the radius of a standard single-mode fiber (SMF), is inserted between standard SMFs to form an extremely simple in-fiber modal interferometer. The wavelength of the transmission dip increases linearly with the temperature. Experimental demonstration shows that it can be used to sense temperature up to 850 degrees C with a sensitivity of about 18.3 pm/degrees C.

  • 122637.
    Zhu, Jiqing
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Storage Stability and Phase Separation Behaviour of Polymer-Modified Bitumen: Characterization and Modelling2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Polymermodifierade bitumen (PMB) är ett högpresterande material för väganläggning och underhåll. Men PMB:s lagringsstabilitet och fassepareringsegenskaper är inte tillräckligt förstådda än och behöver studeras för en mer framgångsrik och hållbar användning av PMB. I denna avhandling studeras termodynamisk jämvikt och fasseparation av PMB med målsättning att uppnå en grundläggande förståelse av PMB:s lagringsstabilitet och fassepareringsegenskaper. Utvecklingen av polymermodifierade bitumen sammanfattas. Fasseparationsprocessen av instabil PMB:s studeras med hjälp av fluorescens mikroskopi vid lagringstemperatur (180 °C). En kopplad fas-fälts modell som beskriver diffusion och flöde har utvecklats för att simulera och förutsäga PMB:s lagringsstabilitet och fassepareringsegenskaper. Temperaturberoendet hos PMB:s fasseparation har beskrivits genom att införa temperaturberoende modellparametrar mellan 140 °C och 180 °C. Denna modell är införd i ett finit element program och kalibrerad med experimentella observationer på verkliga PMB. Resultaten indikerar att lagringsstabiliteten och fasseparationen hos PMB är starkt beroende av den specifika kombinationen av basbitumen och polymer. En instabil PMB börjar separera i två faser genom diffusion, beroende på dålig bitumen-polymer kompatibilitet. När skillnaden i densitet mellan de två faserna blir tillräckligt stor kommer gravitationen att driva flödet av de två faserna och accelerera separationen i vertikalled. Den föreslagna modellen, baserad på Cahn-Hilliards ekvation, Flory-Huggins teori och Navier-Stokes ekvation, kan beskriva stabilitetsskillnaderna mellan de undersökta PMB:erna och deras distinkta mikrostruktur vid olika temperaturer. De olika materialparametrarna hos PMB bestämmer skillnaden i fassepareringsegenskaper i termer av stabilitet och temperaturberoende. Den utvecklade modellen kan simulera och förklara de resulterande skillnaderna på grund av materialparametrarna. Resultatet av denna studie kan bidra till att säkerställa lagringsstabilitet och hållbara applikationer för PMB.

  • 122638.
    Zhu, Jiqing
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Towards a Viscoelastic Model for Phase Separation in Polymer Modified Bitumen2015Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In this thesis, a review is given on the most popular polymers used today for polymer modification of bitumen. Furthermore, the development of a model for phase separation in polymer modified bitumen (PMB) is proposed, that will enable a better control and understanding of PMB phase behaviour, allowing thus to enhanced long-term performance. PMB is hereby considered as a blend and focus is placed on its structure, its equilibrium thermodynamics and its phase separation dynamics. The effects of dynamic asymmetry on phase separation in PMB are analysed with related theories and some image data. Based on the discussion in this thesis, it is concluded that the effects of dynamic asymmetry between bitumen and polymer should be taken into consideration when studying phase separation in PMB. By analysing related literature and image data, it is found that some features of viscoelastic phase separation are shown during the phase separation process in some PMBs. It is therefore possible and useful to develop a viscoelastic model for PMB to describe its phase separation behaviour. In this, the stress-diffusion coupling is expected to play a key role in the model. Finally, recommendations are made towards the future research which is needed to realize the proposed model.

  • 122639.
    Zhu, Jiqing
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Balieu, Romain
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Lu, Xiaohu
    Kringos, Nicole
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Microstructure evaluation of polymer-modified bitumen by image analysis using two-dimensional fast Fourier transform2018Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 137, s. 164-175Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aiming to quantitatively evaluate the microstructure of polymer-modified bitumen (PMB) for roads, this paper employs the two-dimensional fast Fourier transform(2D-FFT) to process the microscopic and numerical images of four PMBs. The related derivative parameters, including the characteristic frequency and wavelength, are computed from the 2D-FFT power spectrum. The results show that the absence/presence of a characteristic frequency (range) on the power spectrum can indicate the lack/existence of the corresponding periodical structural pattern(s) in the original PMB image. A lower characteristic frequency usually represents a coarser PMB microstructure while a higher one implies a finer PMB microstructure. The 2D-FFT method is thus valid for differentiating various PMB microstructures. The proposed method is also capable of quantitatively evaluating the effects of temperature and the temporal evolution of PMB microstructure during phase separation. As the separation continues, the decrease of characteristic frequency indicates the coarsening process of a PMB microstructure. Additionally, the numerical reproduction of the observed phase separation is evaluated with the same method. The quantitative comparison with the experimental results reveals that the simulations fairly reproduced the microscopy observation results despite some deviation. The proposed method provides a foundation for the microstructure-based modelling of PMB performance in the future.

  • 122640.
    Zhu, Jiqing
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Balieu, Romain
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Lu, Xiaohu
    Nynas AB.
    Kringos, Niki
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Numerical investigation on phase separation in polymer modified bitumen: Effect of thermal condition2017Ingår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    With the aim to understand the effect of thermal condition on phase separation in polymer-modified bitumen (PMB), this paper numerically investigates four PMB binders under five thermal conditions between 140 and 180 °C. Based on a phase-field model previously developed by the authors for PMB phase separation, the updated model presented in this paper uses temperature-dependent parameters in order to approach the concerned temperature range, including mobility coefficients, interaction and dilution parameters. The model is implemented in a finite element software package and calibrated with the experimental observations of the four PMBs. The experimental results are well reproduced by the model, and it is thus believed that the calibrated parameters can represent the four PMBs. The simulation results indicate that the model proposed in this paper is capable of capturing the stability differences among the four PMBs and their distinct microstructures at different temperatures. Due to the transition of some PMBs from the thermodynamically stable state at 180 °C to the unstable state at 140 °C, a homogenization process may occur during the cooling applied numerically. After the transition, the PMBs start to separate into two phases and gradually form the binary structures controlled by the temperature. It is indicated that the cooling rate slightly affects the final pattern of the PMB binary microstructure, although the process can be more complicated in reality due to the potential dynamic reasons.

  • 122641.
    Zhu, Jiqing
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Balieu, Romain
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Lu, Xiaohu
    Nynas AB.
    Kringos, Niki
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Numerical Prediction of Storage Stability of Polymer-Modified Bitumen: A Coupled Model of Gravity-Driven Flow and Diffusion2017Ingår i: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, Vol. 2632, s. 70-78Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A coupled diffusion–flow model by phase-field method is proposed in this paper with the goal of predicting the storage stability of polymer-modified bitumen (PMB). In this study, the incompressible Navier–Stokes equations were coupled with a previously developed phase-field model for PMB phase separation. The coupled model was implemented in a finite element software package with experimentally calibrated parameters and reported data in the literature. Effects of the parameters (bitumen density and dynamic viscosity) that affected the gravity-driven flow and phase separation in PMB were evaluated at 180°C with the simulation results. The results indicate that the coupled diffusion–flow model can predict the storage stability (and instability) of PMBs. A good correlation between the simulation results and the previously reported experimental results (storage stability tube test) was observed. The different gravity-driven phase separation behaviors of PMBs might have resulted from the different composition of the equilibrium phases in the PMBs as well as the different densities and dynamic viscosities of the individual components (polymer and bitumen). A bigger polymer–bitumen density difference, a lower bitumen dynamic viscosity, or both caused a faster flow and separation in the PMB at storage temperature. The investigated variation of bitumen dynamic viscosity had a more significant influence than the investigated variation of bitumen density in this study, but this finding might depend on the specific values of the model parameters. With this study as a foundation, further experimental and numerical studies will be conducted to increase understanding of storage-stable PMB binders and to develop a more efficient test method for determining PMB storage stability.

  • 122642.
    Zhu, Jiqing
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Birgisson, Björn
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Kringos, Niki
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Polymer modification of bitumen: Advances and challenges2014Ingår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 54, nr 1, s. 18-38Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Advances and challenges in the field of bitumen polymer modification for road construction during the last 40 years are reviewed in this paper. The history of bitumen polymer modification is described chronologically. Some popular plastomers and thermoplastic elastomers in bitumen modification are discussed regarding their advantages and disadvantages, including polyethylene (PE), polypropylene (PP), ethylene-vinyl acetate (EVA), ethylene-butyl acrylate (EBA), styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS) and styrene-ethylene/butylene-styrene (SEBS). Although these polymers all improve bitumen properties to some extent, there are still some drawbacks limiting the future development of bitumen polymer modification, such as high cost, low ageing resistance and poor storage stability of polymer modified bitumen (PMB). Researchers attempted various ways to remove these drawbacks. Some technical developments for removing drawbacks are reviewed in this paper, including saturation, sulfur vulcanization, adding antioxidants, using hydrophobic clay minerals, functionalization and application of reactive polymers. The future development of polymers for bitumen modification is analyzed as well. Since it is currently challenging to perfectly achieve all expected PMB properties at the same time, some compromised recommendations are given in this paper, among which greatly enhancing the properties with an acceptably high cost, significantly reducing the cost with relatively poor properties and their combinations. Functionalization is emphasized as a promising way to enhance the properties of currently used polymers and develop new-type polymer modifiers with much greater success in the future. It is also recommended that future research on bitumen polymer modification focuses more on function development towards enhancing: adhesion with aggregates, long-term performance and recyclability.

  • 122643.
    Zhu, Jiqing
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Kringos, Niki
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Towards the development of a viscoelastic model for phase separation in polymer-modified bitumen2015Ingår i: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 16, nr S1, s. 39-49Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development of a viscoelastic model for phase separation in polymer-modified bitumen (PMB) is proposed in this paper. PMB is considered as a pseudo-binary blend. Equilibrium thermodynamics and phase separation dynamics of PMB are discussed. The effects of dynamic asymmetry on phase separation in PMB are analysed with related theories and some image data. Based on the discussion in this paper, it is concluded that the effects of dynamic asymmetry between bitumen and polymer should be taken into consideration when studying phase separation in PMB. By analysing related literature and image data, it is found that some features of viscoelastic phase separation are shown during the phase separation process in some PMBs. It is possible to develop a viscoelastic model for PMB to describe its phase separation behaviour. The stress-diffusion coupling would play a key role in the model by introducing composition-dependant mobility, shear and bulk stress.

  • 122644.
    Zhu, Jiqing
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Lu, Xiaohu
    Nynas AB.
    Balieu, Romain
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Kringos, Niki
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Modelling and numerical simulation of phase separation in polymer modified bitumen by phase-field method2016Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 107, s. 322-332Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, a phase-field model with viscoelastic effects is developed for polymer modified bitumen (PMB) with the aim to describe and predict the PMB storage stability and phase separation behaviour. The viscoelastic effects due to dynamic asymmetry between bitumen and polymer are represented in the model by introducing a composition-dependent mobility coefficient. A double-well potential for PMB system is proposed on the basis of the Flory-Huggins free energy of mixing, with some simplifying assumptions made to take into account the complex chemical composition of bitumen. The model has been implemented in a finite element software package for pseudo-binary PMBs and calibrated with experimental observations of three different PMBs. Parametric studies have been conducted. Simulation results indicate that all the investigated model parameters, including the mobility and gradient energy coefficients, interaction and dilution parameters, have specific effects on the phase separation process of an unstable PMB. In addition to the unstable cases, the model can also describe and predict stable PMBs. Moreover, the phase inversion phenomenon with increasing polymer content in PMBs is also well reproduced by the model. This model can be the foundation of an applicable numerical tool for prediction of PMB storage stability and phase separation behaviour.

  • 122645.
    Zhu, Jiqing
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Lu, Xiaohu
    Nynas AB.
    Kringos, Niki
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Experimental investigation on storage stability and phase separation behaviour of polymer-modified bitumen2018Ingår i: The international journal of pavement engineering, ISSN 1029-8436, E-ISSN 1477-268X, Vol. 19, nr 9, s. 832-841Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Storage stability and phase separation behaviour of four styrene-butadiene-styrene (SBS) polymer-modified bitumen (PMB) binders are investigated by conventional binder tests and fluorescence microscopy in this paper. Since no separation happened in the stable PMBs, research focus was placed on capturing and analysing the phase separation process in the unstable PMBs. A phase inversion phenomenon was observed in one unstable PMB during the phase separation, showing the possible viscoelastic effects. Furthermore, it is indicated that criteria only based on compositional parameters can give misleading predictions of PMB storage stability. New criteria still need to be defined. The potential approaches to PMB phase behaviour prediction are reviewed and exploratively discussed in the context of the four investigated PMBs. This leads to a further discussion on the possibility of having a thermodynamic approach to PMB phase behaviour prediction by looking into the free energy of PMB. The Flory–Huggins theory provides a way to do this, upon the consideration of PMB as a pseudo-binary blend and some made assumptions. Free energy curves have the strength of giving more information like the equilibrium phase composition. In addition, some more aspects should be also considered for PMB phase behaviour prediction towards an applicable criterion.

  • 122646.
    Zhu, Jixiang
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Computation Offloading and Task Scheduling among Multi-Robot Systems2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I ett Multi-Robot System (MRS) samarbetar flertalet robotar för att utföra uppgifter som en ensam robot inte klarar av. På grund av molnets hastiga utveckling och vida exploatering kan det utöka resurserna en robot kan få tillgång till och innebär därmed potentiella fördelar för robotik- och automatiseringssystem. En av dessa potentiella fördelar är beräkningsavlastning (computation offloading) som innebär att de beräkningstunga delarna av en applikation utförs på en server för att minska exekveringstiden. För att möjliggöra beräkningsavlastning måste man dock först svara på när, vad, vart, och hur man skall avlasta? Trots att vissa avlastnings-mekanismer har föreslagits inom området av mobil beräkning (dvs smartphones, pads), förblir dessa frågor till en stor del obesvarade och många nya utmaningar är troliga att uppstå inom världen av robotik.

    Denna rapport ämnar applicera beräkningsavlastning på ett Multi-Robotsystem och undersöka dess effekt på prestandan (beräkningstid) för robotapplikationer. Till detta ändamål så föreslås ett avlastnings-ramverk för en elastisk beräkningsmodell med en molnstruktur utgjord av två lager: en allmän infrastruktur och en ad-hoc baserat lokalt nätverk (fog) uppbyggt av ett kluster av robotar. Två schemaläggnings algoritmer: Heterogeneous-Earlist-Finish-Time (HEFT) och CriticalPath-on-a-Processor (CPOP) är implementerade för att schemalägga de avlastade uppgifterna åt tillgängliga robotar och servrar så att applikationens totala exekveringstid är minimerad. Avlastnings-ramverket är implementerat baserat på Robot Operating System (ROS) och testat med hjälp av simulerade applikationer. Resultaten demonstrerar genomförbarheten av det föreslagna avlastnings-ramverket och att utnyttjandet av avlastningsteknik innebär en potentiellt snabbare exekvering för robotapplikationer.

  • 122647.
    Zhu, Jun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    Energy and Design Cost Efficiency for Streaming Applications on Systems-on-Chip2009Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    With the increasing capacity of today's integrated circuits, a number ofheterogeneous  system-on-chip (SoC)  architectures  in embedded  systemshave been proposed. In order to achieve energy and design cost efficientstreaming applications  on these  systems, new design  space explorationframeworks  and  performance  analysis  approaches are  required.   Thisthesis  considers three state-of-the-art  SoCs architectures,  i.e., themulti-processor SoCs (MPSoCs)  with network-on-chip (NoC) communication,the hybrid CPU/FPGA architectures, and the run-time reconfigurable (RTR)FPGAs.  The main topic of the  author?s research is to model and capturethe  application  scheduling,  architecture  customization,  and  bufferdimensioning  problems, according to  the real-time  requirement.  Sincethese  problems  are NP-complete,  heuristic  algorithms and  constraintprogramming solver are used to compute a solution.For  NoC  communication  based  MPSoCs,  an  approach  to  optimize  thereal-time    streaming    applications    with   customized    processorvoltage-frequency levels and memory  sizes is presented. A multi-clockedsynchronous  model  of  computation   (MoC)  framework  is  proposed  inheterogeneous  timing analysis and  energy estimation.   Using heuristicsearching  (i.e., greedy  and  taboo search),  the  experiments show  anenergy reduction (up to 21%)  without any loss in application throughputcompared with an ad-hoc approach.On hybrid CPU/FPGA architectures,  the buffer minimization scheduling ofreal-time streaming  applications is addressed.  Based  on event models,the  problem  has  been  formalized  decoratively  as  constraint  basescheduling,  and  solved  by  public domain  constraint  solver  Gecode.Compared  with  traditional  PAPS  method,  the  proposed  method  needssignificantly smaller  buffers (2.4%  of PAPS in  the best  case), whilehigh throughput guarantees can still be achieved.Furthermore, a  novel compile-time analysis approach  based on iterativetiming  phases is  proposed  for run-time  reconfigurations in  adaptivereal-time   streaming   applications  on   RTR   FPGAs.   Finally,   thereconfigurations analysis and design trade-offs analysis capabilities ofthe proposed  framework have been  exemplified with experiments  on bothexample and industrial applications.

  • 122648.
    Zhu, Jun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    Performance Analysis and Implementationof Predictable Streaming Applications onMultiprocessor Systems-on-Chip2010Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Driven by the increasing capacity of integrated circuits, multiprocessorsystems-on-chip (MPSoCs) are widely used in modern consumer electron-ics devices. In this thesis, the performance analysis and implementationmethodologies are explored to design predictable streaming applications onMPSoCs computing platforms. The application functionality and concur-rency are described in synchronous data flow (SDF) computational models,and two state-of-the-art architecture templates are adopted as multiproces-sor architectures, i.e., network-on-chip (NoC) based MPSoC and hybrid re-configurable CPU/FPGA platforms. Based on the author’s contributions onsimulation and formal analytical methods, performance analysis and designspace exploration for embedded MPSoCs architectures have been addressed.

    An energy efficient design space exploration flow is proposed for stream-ing applications with guaranteed throughput on NoC based MPSoCs, in whichboth application throughput analysis and system energy calculation are car-ried out by simulation on a multi-clocked synchronous modelling frame-work. On the other hand, based on event models of data streams, a formalanalytical scheduling framework for real-time streaming applications withminimal buffer requirement on hybrid CPU/FPGA architectures is exploited.The scheduling problem has been formalized declaratively by constraint basetechniques, and solved by a public domain constraint solver. Consecutively,the constraint based method has been extended to solve problems rangingfrom global computation/communication scheduling and reconfiguration anal-ysis to Pareto efficient design. Finally, a prototype of stream processing sys-tem on FPGA based MPSoC is built to substantiate the results from theoreti-cal studies in this thesis.

  • 122649.
    Zhu, Jun
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    Jantsch, Axel
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    Sander, Ingo
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    SDF to Synchronous Cross Domain Analysis in ForSyDe Stream Processing Framework2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    Stream processing has been a very active field in parallel programming for its suitability to expressthe concurrent architecture in embedded systems. Caused by its concurrent reasoning features,stream programming frameworks are built on some abstract models of computation (MoCs) tohandle the complexity and unpredictability. To allow us focus on the essential issues of time,communication and synchronisation of the parallel tasks, the support from a sound heterogeneousMoCs framework to stream application system is still in need. ForSyDe is our high levelexecutable design framework to express multi-computational-models, based on stream processingconcept. It is a heterogeneous diagram to describe intricate application behaviors, and offers crossdomain analysis features to support multi-domains integration and optimization. A case study inForSyDe framework shows that the communication structure of a stream application in SDFdomain could be migrated to the synchronous domain without any extra work on its computationfunctions. To integrate it with our work on a communication based NoC simulator, we believesome more interesting design exploration work could be done on the analysis of communicationand computation efforts, besides power issues.

  • 122650.
    Zhu, Jun
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    Sander, Ingo
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    Jantsch, Axel
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    Buffer Minimization of Real-Time Streaming Applications Scheduling on Hybrid CPU/FPGA Architectures2009Ingår i: DATE: 2009 DESIGN, AUTOMATION & TEST IN EUROPE CONFERENCE & EXHIBITION, 2009, s. 1506-1511Konferensbidrag (Refereegranskat)
    Abstract [en]

    We address the problem of real-time streaming applications scheduling on hybrid CPU/FPGA architectures. The main contribution is a two-step approach to minimize the buffer requirement for streaming applications with throughput guarantees. A novel declarative way of constraint based scheduling for real-time hybrid SW/HW systems is proposed, while the application throughput is guaranteed by periodic phases in execution. We use a voice-band modem application to exemplify the scheduling capabilities of our method. The experimental results show the advantages of our techniques in both less buffer requirement and higher throughput guarantees compared to the traditional PAPS method.

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