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  • 122851.
    Zmijewski, Nicholas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Vattendragsteknik.
    Bottacin-Busolin, Andrea
    University of Manchester, UK.
    Wörman, Anders
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Vattendragsteknik.
    Incorporating Hydrologic Routing into Reservoir Operation Models: Implications for Hydropower Production Planning2016Ingår i: Water resources management, ISSN 0920-4741, E-ISSN 1573-1650, Vol. 30, nr 2, s. 623-640Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Increased reliance on variable and intermittent energy sources is likely to lead to a change in the production strategies of hydropower, thereby increasing the importance of accurate forecasting of production. For optimization models applied to water reservoirs, the computational cost increases with the number of reservoirs and future time-steps considered, often requiring simplification of the physical description of the flow dynamics. Here it is demonstrated that deficiency of the model of the flow dynamics on stream-reaches gives rise to errors in short-term planning, which leads to sub-optimal production. Here a simplified hydraulic model based on the kinematic-diffusion wave model was incorporated in the optimization of reservoir production planning. The time-lag distributions of the streams were evaluated for River Dalälven and implemented in a computationally efficient form of the kinematic-diffusion wave equation incorporated in a production optimization algorithm for a series of reservoirs. Compared to using a single time-lag for the water transfer on flow reaches between hydropower stations, the wave diffusion was found to affect the management as a deviation between the actual production and the planned production. The deviation was found to increase with increasing short-term regulation and decreasing Peclet number below about 10. For a sufficiently high Peclet number and long wavelength characterizing individual stream reaches, the distribution of time-lags become sufficiently narrow to motivate being replaced by a simpler description such as the constant time-lag.

  • 122852.
    Zmijewski, Nicholas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Vattendragsteknik.
    Wörman, Anders
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Vattendragsteknik.
    Coupled geomorphologic dispersion and reservoir managementManuskript (preprint) (Övrigt vetenskapligt)
  • 122853.
    Zmijewski, Nicholas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Vattendragsteknik.
    Wörman, Anders
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Vattendragsteknik.
    Hydrograph variances over different timescales in hydropower production networks2016Ingår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 52, nr 8, s. 5829-5846Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The operation of water reservoirs involves a spectrum of timescales based on the distribution of stream flow travel times between reservoirs, as well as the technical, environmental, and social constraints imposed on the operation. In this research, a hydrodynamically based description of the flow between hydropower stations was implemented to study the relative importance of wave diffusion on the spectrum of hydrograph variance in a regulated watershed. Using spectral decomposition of the effluence hydrograph of a watershed, an exact expression of the variance in the outflow response was derived, as a function of the trends of hydraulic and geomorphologic dispersion and management of production and reservoirs. We show that the power spectra of involved time-series follow nearly fractal patterns, which facilitates examination of the relative importance of wave diffusion and possible changes in production demand on the outflow spectrum. The exact spectral solution can also identify statistical bounds of future demand patterns due to limitations in storage capacity. The impact of the hydraulic description of the stream flow on the reservoir discharge was examined for a given power demand in River Dalälven, Sweden, as function of a stream flow Peclet number. The regulation of hydropower production on the River Dalälven generally increased the short-term variance in the effluence hydrograph, whereas wave diffusion decreased the short-term variance over periods of <1 week, depending on the Peclet number (Pe) of the stream reach. This implies that flow variance becomes more erratic (closer to white noise) as a result of current production objectives.

  • 122854.
    Zmijewski, Nicholas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Vattendragsteknik.
    Wörman, Anders
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Vattendragsteknik.
    Trade-Offs between phosphorous discharge and hydropower production using reservoir regulation2017Ingår i: Journal of water resources planning and management, ISSN 0733-9496, E-ISSN 1943-5452, Vol. 143, nr 9, artikel-id 04017052Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The management of water flow using reservoirs for the purpose of hydropower production can have significant impacts on solute transport. Reducing the phosphorous load to downstream areas can be of great importance for aquatic habitats associated with recipient waters, as well as for the overall health of coastal and estuary areas. This study demonstrates a combined operation of a network of reservoirs with the objectives of hydropower production and improvement of water quality in downstream areas using a multiobjective approach and incorporating the transport of phosphorous in the watershed. A genetic optimization method was used to determine the trade-off between power production and mitigation of phosphorous discharge in the reservoir network of the Dalälven River, Sweden. The phosphorous export can be reduced (-5%) with a limited loss of power production (-4.3%), but further reduction is associated with a significant loss in total power production. The trade-off between the two objectives is determined using Pareto diagrams and examined for varying particulate conditions.

  • 122855.
    Zoghi, Sedigheh
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geodesi och satellitpositionering.
    On the statistical tests over Fennoscandian GNSS/levelling networks2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In Geodesy and Surveying we work with a large amount of observations which alwayscontains different types of errors. The errors decrease the quality of the observations andpropagate to the results. Therefore, detection and removing the gross errors are of vitalimportance. The Global Navigation Satellite Systems (GNSS) can be used to measure theellipsoidal height and by subtracting an existing geoid height from that, the orthometric heightcan be determined. There is a simple linear relation amongst these triple heights, whichcannot be fulfilled due to the presence of different types of error. One of the important sort ofthese errors is gross errors.This study concerns about investigation and detection of blunders or gross errors on the 4346GNSS/levelling points over Fennoscandia. Each country has its own data set with specificprecision. The well-known gravity model EGM08 is used to compute the geoid heights withrespect to WGS84 reference ellipsoid. We have a large amount of data and we expect thattheir errors follow the normal distribution. The main aim of this thesis is to apply some datascreening methods both before and after adjustment process in such a way that the normaldistribution of the data set is achieved by eliminating the erroneous data. This will be done byperforming the pre- and post-adjustment data screening. For the pre-adjustment we performeddata filtering, test of normality of observations and test of their variances for theGNSS/levelling data over Sweden, Denmark, Norway and Finland. We used the 4-, 5- and 7-parameter corrective surfaces for modelling the systematic trends of the differences betweenthe EGM08 geoid model and the ellipsoidal and orthometric height differences. The test ofnormality of residuals, global test of variance, Baarda’s data snooping and Tau test will beperformed after the removal of the trends. Numerical studies show that the GNSS/levellingdata of Sweden, Denmark and Finland are of good qualities, but the claimed errors for thedata are rather optimistic. The situation was complicated for the data of Norway and we couldnot see the normality of the data and even the claimed accuracies seem to be optimistic.

  • 122856.
    Zografos, Alexandros
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Wireless Sensor-based Agricultural Monitoring System2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Idag när energiresurser blir allt knappare och knappare blir de även mer värdefulla. I samband med befolkningstillväxten under förra århundradet har behovet av att hitta nya, mer effektiva och hållbara metoder inom jordbruket och livsmedelsproduktion blivit av allt större vikt. . För att underlätta denna process har vi designat, byggt och utvärderat ett system för precisionsjordbruk som ger bönder mer användbara data om jorden, vattenförsörjning och det allmänna tillståndet i sina områden på ett användarvänligt och lättillgängligt sätt. Vårt system syftar till att göra odling och bevattning effektivare då bonden kan fatta bättre underbyggda beslut och därmed spara tid och resurser.

    Mångfalden av läget och jordbrukets klimatpåverkan, tillsammans med andra miljöparametrar över tiden gör bondens beslutsprocess mer komplicerad än tidigare och kräver ytterligare empirisk kunskap. Att tillämpa trådlösa sensornätverk för övervakning av dessa parametrar och att presentera? denna information med en användarvänlig skräddarsydd webbtjänst kan göra det möjligt för jordbrukare att utnyttja på ett effektivt sätt nåde bästa resultaten från sitt jordbruk. Systemet kan skala utifrån varje bondes krav och den insamlade data kan utgöra en värdefull resurs för ett framtida jordbruk, utöver dess användning för dagens bondes beslut. Utformningen av systemet för precisionsjordbruk innehåller en prototyplösning avseende sensorplattformen och en anpassningsbar tjänst som kan användas på olika sätt och av flera enheter.

  • 122857.
    Zografos, Dimitrios
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Ghandhari, Mehrdad
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Estimation of Power System Inertia2016Ingår i: Power and Energy Society General Meeting (PESGM), 2016 17-21 July 2016, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    Information about power system inertia is of utmost importance for the Transmission System Operators (TSOs), so that it can be guaranteed that the stability of the system is not under risk. A new offline inertia estimation method is proposed in this paper. The method includes the calculation of the total power change after a disturbance in the system, based on selection of appropriate time ranges of the Rate Of Change Of Frequency(ROCOF) curve. Nordic32 test system is used for the simulations, where different disturbances, load dynamics and data processing tools are considered. Finally, a comparison of the proposed method to two methods proposed in the past takes place.

  • 122858.
    Zografos, Dimitrios
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Ghandhari, Mehrdad
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Power system inertia estimation by approaching load power change after a disturbance2017Ingår i: Power & Energy Society General Meeting, 2017 IEEE, Chicago, IL, USA: Institute of Electrical and Electronics Engineers (IEEE), 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    The substitution of conventional synchronous power plants by intermittent generation leads to reduced power system inertia. This transition deteriorates system's frequency response and necessitates the estimation of power system inertia, so that adequate power resources are preserved. An offline estimation method is proposed in this paper, which aims to estimate the power change of the loads due to voltage dependency after a disturbance. To do that, data available at the generator buses are employed. The proposed method is applied on a modified version of Nordic32 test system under twenty different scenarios, which include generator and load disconnections. Finally, a comparison with two offline methods presented in the past literature takes place and demonstrates the advantages and disadvantages of the proposed method.

  • 122859.
    Zografos, Dimitrios
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Ghandhari, Mehrdad
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Eriksson, R.
    Power system inertia estimation: Utilization of frequency and voltage response after a disturbance2018Ingår i: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 161, s. 52-60Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Power system inertia is gradually being reduced due to the ongoing replacement of conventional synchronous power plants by intermittent generation. This affects the frequency response of the system and necessitates the estimation of power system inertia, so that sufficient power reserves are retained. This paper contributes with a novel disturbance-based inertia estimation method, that simultaneously estimates the power change after a disturbance. The proposed method accommodates the frequency and voltage dynamics, which significantly affect the system's power change, and hence the inertia estimation. Two separate approaches – that are also capable of standing alone – are combined, in order to accommodate the dynamics. An extended version of the Nordic32 test system is used for the application of the method, where several case studies and a comparison are investigated, so as to examine the method's accuracy and robustness.

  • 122860.
    Zografos, Dimitrios
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Ghandhari, Mehrdad
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Paridari, Kaveh
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Estimation of power system inertia using particle swarm optimization2017Ingår i: 2017 19th International Conference on Intelligent System Application to Power Systems, ISAP 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, artikel-id 8071383Konferensbidrag (Refereegranskat)
    Abstract [en]

    Power system inertia is being globally reduced, due to the substitution of conventional synchronous power plants by intermittent generation. This threatens the frequency stability of the system and makes the estimation of power system inertia necessary, so that proactive measures can be imposed. A disturbance-based method is proposed in this paper, which estimates the total inertia constant of the power system. The method applies particle swarm optimization (PSO) to minimize a cost function, which is defined based on the swing equation. To do that, data available at the generator buses are employed. The proposed method is applied on the Nordic57 test system under twenty different scenarios, which include generator and load disconnections. Furthermore, a comparison with two methods presented in the literature is performed and demonstrates the higher performance of the proposed method, in the sense of the mean and the variance of the errors.

  • 122861.
    Zografos, Dimitrios
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Rabuzin, Tin
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Ghandhari, Mehrdad
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Eriksson, Robert
    Prediction of Frequency Nadir by Employing a Neural Network Approach2018Ingår i: 2018 IEEE PES Innovative Smart Grid Technologies Conference Europe (ISGT-Europe), Institute of Electrical and Electronics Engineers (IEEE), 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    The increased integration rate of inverter-interfaced devices is affecting the frequency response of the modern power systems. This leads to an increase of the variability of the power generation and to a reduction of the total system's inertia. This evolution of the system necessitates the prediction of frequency metrics, so that the frequency stability of the system can be guaranteed and that necessary mitigation measures can be taken. This paper proposes a method to predict the frequency nadir by using a Neural Network (NN) approach. As the approach uses measurements during a first short time period after the event, it more accurately predicts the frequency nadir compared to using static values. Several inputs for the NN are examined and when the appropriate ones are selected, a highly accurate prediction is accomplished.

  • 122862.
    Zohdi, Zeynab
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. Karolinska Inst, Dept Clin Neurosci, Ctr Psychiat Res, SE-17176 Solna, Sweden ; Univ Bu Ali Sina, Dept Chem, Hamadan 65174, Iran.
    Hashemi, Mahdi
    Univ Bu Ali Sina, Dept Chem, Hamadan 65174, Iran..
    Uheida, Abdusalam
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Moein, Mohammad Mahdi
    Karolinska Inst, Dept Clin Neurosci, Ctr Psychiat Res, SE-17176 Solna, Sweden..
    Abdel-Rehim, Mohamed
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. Karolinska Inst, Dept Clin Neurosci, Ctr Psychiat Res, SE-17176 Solna, Sweden Dept Appl Phys, SE-16440 Stockholm, Sweden..
    Graphene Oxide Tablets for Sample Preparation of Drugs in Biological Fluids: Determination of Omeprazole in Human Saliva for Liquid Chromatography Tandem Mass Spectrometry2019Ingår i: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 24, nr 7, artikel-id 1191Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, a novel sort of sample preparation sorbent was developed, by preparing thin layer graphene oxide tablets (GO-Tabs) utilizing a mixture of graphene oxide and polyethylene glycol on a polyethylene substrate. The GO-Tabs were used for extraction and concentration of omeprazole (OME) in human saliva samples. The determination of OME was carried out using liquid chromatography-tandem mass spectrometry (LC-MS/MS) under gradient LC conditions and in the positive ion mode (ESI+) with mass transitions of m/z 346.3 -> 198.0 for OME and m/z 369.98 -> 252.0 for the internal standard. Standard calibration for the saliva samples was in the range of 2.0-2000 nmol L-1. Limits of detection and quantification were 0.05 and 2.0 nmol L-1, respectively. Method validation showed good method accuracy and precision; the inter-day precision values ranged from 5.7 to 8.3 (%RSD), and the accuracy of determinations varied from -11.8% to 13.3% (% deviation from nominal values). The extraction recovery was 60%, and GO-Tabs could be re-used for more than ten extractions without deterioration in recovery. In this study, the determination of OME in real human saliva samples using GO-Tab extraction was validated.

  • 122863. Zois, D. -S
    et al.
    Levorato, Marco
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Mitra, U.
    Non-linear smoothers for discrete-time, finite-state Markov chains2013Ingår i: IEEE International Symposium on Information Theory: Proceedings, 2013, s. 2099-2103Konferensbidrag (Refereegranskat)
    Abstract [en]

    The problem of enhancing the quality of system state estimates is considered for a special class of dynamical systems. Specifically, a system characterized by a discrete-time, finite-state Markov chain state and observed via conditionally Gaussian measurements is assumed. The associated mean vectors and covariance matrices are tightly intertwined with the system state and a control input selected by a controller. Exploiting an innovations approach, finite-dimensional, non-linear approximate MMSE smoothing estimators are derived for the Markov chain system state. The resulting smoothers are driven by a control policy determined by a stochastic dynamic programming algorithm, which minimizes the MSE filtering error, and was proposed in our earlier work. An application of the smoothers derived in this paper is presented for the problem of physical activity detection in wireless body sensing networks, which illustrates the performance enhancement due to smoothing.

  • 122864. Zolesi, V. S.
    et al.
    Ganga, P. L.
    Scolamiero, L.
    Micheletti, A.
    Podio-Guidugli, P.
    Tibert, Gunnar
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strukturmekanik.
    Donati, A.
    Ghiozzi, M.
    On an innovative deployment concept for large space structures2012Ingår i: 42nd International Conference on Environmental Systems 2012, ICES 2012, American Institute of Aeronautics and Astronautics, 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    Large deployable space structures are mission-critical technologies for which deployment failure cannot be an option. The difficulty to fully reproduce and test on ground the deployment of large systems dictates the need for extremely reliable architectural concepts. In 2010, ESA promoted a study focused at the pre-development of breakthrough architectural concepts offering superior reliability. The study, which was performed as an initiative of ESA Small Medium Enterprises Office (http://www.esa.int/SME/), by Kayser Italia at its premises in Livorno (Italy), with Universita' di Roma TorVergata (Rome, Italy) as sub-contractor and consultancy from KTH (Stockholm, Sweden), led to the identification of an innovative large deployable structure of "tensegrity" type, which achieves the required reliability because it permits a drastic reduction in the number of articulated joints in comparison with non-tensegrity architectures. The identified target application was in the field of large antenna reflectors. The project focused on the overall architecture of a deployable system and the related design implications. With a view toward verifying experimentally the performance of the deployable structure, a reduced-scale breadboard model was designed and manufactured. A gravity off-loading system was designed and implemented, so as to check deployment functionality in a 1-g environment. Finally, a test campaign was conducted, to validate the main design assumptions as well as to ensure the concept's suitability for the selected target application. The test activities demonstrated satisfactory stiffness, deployment repeatability, and geometric precision in the fully deployed configuration. The test data were also used to validate a finite element model, which predicts a good static and dynamic behavior of the full-scale deployable structure.

  • 122865.
    Zolfaghari, Anahita
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Transparant högtalare: Konstruktion, förpackning och montering2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Denna rapport beskriver ett examensarbete utfört på Institutionen för Maskinkonstruktion på Kungliga Tekniska högskolan (KTH) i samarbete med det svenska designföretaget People People. Projektet utfördes under sex månader och målet var att vidareutveckla en befintlig högtalare hos företaget samt att ta fram ett koncept för emballage. People People har tagit fram en högtalare i en låda av glas som tack vare sin transparens smälter in i sin omgivning och tar liten visuell plats. Den är tillräckligt stor för att kunna producera ljud av hög kvalitet. I elektroniklådan i högtalaren finns det möjlighet att koppla in en AirPortExpress som möjliggör trådlös uppspelning av musik från en enhet med WiFi. I dagsläget kan högtalaren levereras färdigmonterad men kunden kan även välja att få endast de ingående komponenterna levererade som ett do-it-yourself-kit (DIY-kit) och själv specialbeställa glaset från en lokal glasmästare. Syftet med examensarbetet är att optimera konstruktionen av högtalaren för att minska antalet lösa komponenter, minska tiden och kostnaden för montering i fabrik samt att öka användarvänligheten vid montering. Vidare ska elektroniken och dess utformning i högtalaren ses över. Elektroniken ska vara kompatibel för en bred marknad och komponenterna ska kopplas på ett sätt som är optimerat för en enkel inkoppling av AirPort Express. Vidare är syftet att ta fram koncept för emballagen, dels för den färdigmonterade produkten samt för DIY-kittet, så att de är optimerade för den pall de kommer lastas på och på så sätt miljövänliga. Genom färre monteringskomponenter minskades tiden för montering och med det kritiska momentet reducerades. De tre hörnskruvarna ersattes med en specialkonstruerad hörnbit för att underlätta och gör monteringen mer intuitiv. Elektroniklådan, som tidigare legat omsluten av glas på baksidan, monterades med lufttillförsel både fram och bak, vilket även möjliggjorde insättning av AirPort Express efter montering. Koncepten för emballagen som togs fram optimerades för transport och lastning på pall. Emballagen dimensionerades efter deras innehåll för att minska materialåtgång.

  • 122866.
    Zolfaghari, Anahita
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Waldner, Carl-Johan
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Bogramp till FRED 252010Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Fred 25 är en båt som ska vara tillgänglig för alla oavsett rörelseförmåga. Den är en 7,5 meter lång aluminiumbåt med bogramp i fören. Målet vid framtagningen av båten har varit att en ensam rullstolsburen skeppare skall kunna hantera båten helt själv. Det finns ett antal problem med båten som måste lösas. I detta projekt har fokus legat på att få fram en billig och effektiv tätning av rampen samt en låsning av rampen som går att automatisera. Dessa problem skall lösas med minimala ändringar på båtens nuvarande konstruktion. Att utveckla bogrampen med dessa krav och önskemål är möjligt, det är dock svårt att få fram optimala koncept då få eller inga ändringar kunde göras på båten. Detta leder till lösningar som motverkar de inbyggda felen istället för att bygga bort dem. Det koncept som valdes för att täta rampens nederkant bestod i en gummiduk som fästes på rampens utsida och skrovet under rampen.För att täta rampens sidor bedömdes en cliplist med rörprofil vara bäst. Cliplisten kläms fast över sargen på rampen och rörprofilen fyller ut glappet mellan ramp och skrov. Den nyframtagna låsningen av rampen bygger på samma princip som tidigare d.v.s. att flärpen fälls över två låsbultar. Tidigare har denna manöver fått göras manuellt men med det framtagna konceptet hissas rampen upp i flärpen och låses på så sätt automatiskt. Tester på Fred 25 med de modifikationer som projektet resulterat i bör göras för en fullständig utvärdering.

  • 122867.
    Zolin Mooses, Jana
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Arkitektur.
    STÖDCENTER FÖR EU-IMMIGRANTER I LILJEHOLMEN2012Självständigt arbete på grundnivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    STÖDCENTER FÖR EU-MIGRANTER I LILJEHOLMEN

    Idag består den snabbast växande gruppen hemlösa i Stockholm av arbetsimmigranter från andra EU-länder .

    Mitt projekt har som syfte att erbjuda denna grupp människor med en byggnad som kan hjälpa dem integreras in i samhället, och fungera som en länk och mellansteg mellan livet i utanförskap och ett värdigt liv med möjlighet till jobb, eget boende och social gemenskap.

  • 122868. Zoller, C. J.
    et al.
    Dentoni Litta, Eugenio
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Primetzhofet, D.
    Characterization of high-k dielectrics using MeV elastic scattering of He ions2015Ingår i: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 347, s. 52-57Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a systematic comparison of two distinct ion-beam based methods for composition analysis of nanometer oxide films: ion-beam channeling and elastic scattering using nuclear resonances, both at MeV energies. Thin films of the technologically highly relevant high-k dielectrics HfO2 and HfAIO are characterized in the present study, with the additional aim of obtaining a better quantification of the Al content for the latter system. We show that both employed ion scattering methods enable a quantitative determination of the oxygen concentrations with typical uncertainties of about 5-10% in the oxygen fraction. The influence of various kinds of systematic inaccuracies in the evaluation procedure are discussed.

  • 122869. Zolyomi, V.
    et al.
    Kollar, J.
    Vitos, Levente
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Anomalous surface relaxation in hcp transition metals2008Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 78, nr 19Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    First-principles total-energy calculations indicate anomalously large surface relaxations for groups IVA and VIIA hcp metals. In addition, for group VIIA elements the magnitude of the layer relaxation exhibits an unusually slow decay with the distance from the surface. We argue that the above phenomena can be traced back to the peculiar Fermi surface of groups IVA and VIIA hcp metals. Namely, the anomalous surface relaxation appears as a consequence of low-energy excitations with near 2k(F) wave vectors, which is also reflected by the flat and degenerate d bands located close to the Fermi level in the L-A-H plane of the hcp Brillouin zone.

  • 122870. Zolyomi, V.
    et al.
    Kollar, J.
    Vitos, Levente
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    On the surface relaxation of transition metals2008Ingår i: Philosophical Magazine, ISSN 1478-6435, E-ISSN 1478-6443, Vol. 88, nr 18-20, s. 2709-2714Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    First principles band structure calculations are presented for the layer relaxation of the close-packed surfaces of 5d transition metals. Anomalously large relaxations are found for group IVA and VIIA hcp metals. For these elements, the size of the layer relaxation exhibits an unusually slow decay with the distance from the surface. We argue that this phenomenon can be attributed to the peculiar flat and degenerate d-bands located close to the Fermi level in the L-A-H top-plane of the hcp Brillouin zone, and which are also responsible for the anomalously low [001] longitudinal optical phonon frequencies observed in these hcp metals.

  • 122871. Zolyomi, V.
    et al.
    Vitos, Levente
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Kwon, S. K.
    Kollar, J.
    Surface relaxation and stress for 5d transition metals2009Ingår i: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 21, nr 9Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Using the density functional theory, we present a systematic theoretical study of the layer relaxation and surface stress of 5d transition metals. Our calculations predict layer contractions for all surfaces, except for the ( 111) surface of face centered cubic Pt and Au, where slight expansions are obtained similarly to the case of the 4d series. We also find that the relaxations of the close packed surfaces decrease with increasing occupation number through the 5d series. The surface stress for the relaxed, most closely packed surfaces shows similar atomic number dependence as the surface energy. Using Cammarata's model and our calculated surface stress and surface energy values, we examine the possibility of surface reconstructions, which is in reasonable agreement with the experimental observations.

  • 122872.
    Zomer, Lara-Britt
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap.
    Daamen, Winnie
    TU Delft.
    Meijer, Sebastiaan
    KTH, Skolan för teknik och hälsa (STH), Hälso- och systemvetenskap, Vårdlogistik.
    Hoogendoorn, Serge
    TU Delft.
    Managing Crowds: The Possibilities and Limitations of Crowd Information During Urban Mass Events2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Thischapter,basedonamixedmethodresearchapproach,offersinsights into possibilities and limitations of using ICT measures for crowd management and distribution during urban mass events (UMEs). Based on literature, practical applications and analyses of research results, we propose crowd management should consider characteristics of both crowds and UMEs to increase information effectiveness. In relation to urban planning, results show that possibilities to influence a crowd’s behavior depend on available (and known) choice sets offered in various locations, while distances towards locations across city centers appear less important. Limitations appear to be related to scarce knowledge on what drives crowd members to adapt or adhere to their activity choice behavior. Such insights are essential for smart cities striving for an optimal use of infrastructural capacity, as both the ambiguous effects of ICT measures, as well as a crowd’s self-organizing capacity should be taken into account for delaying, solving and preventing dis- ruptions of pedestrian flows in city centers. 

  • 122873.
    Zomer, Lara-Britt
    et al.
    KTH, Skolan för teknik och hälsa (STH).
    Moustaid, Elhabib
    KTH, Skolan för teknik och hälsa (STH).
    Meijer, Sebastiaan
    KTH, Skolan för teknik och hälsa (STH).
    A META-MODEL FOR INCLUDING SOCIAL BEHAVIOR AND DATA INTO SMART CITY MANAGEMENT SIMULATIONS2015Ingår i: 2015 WINTER SIMULATION CONFERENCE (WSC), IEEE , 2015, s. 1705-1716Konferensbidrag (Refereegranskat)
    Abstract [en]

    Smart city management can be regarded to bridge different realms of thinking about cities, i.e. 1) the city as complex-adaptive system, 2) socio-technical operational control center and 3) multi-actor policy-making. Underpinned by different world views and theoretical bodies, integration of the three realms puts forward new demands on simulation approaches and challenges current knowledge and available technology regarding integration of sub-models across different systems. In order to support urban transportation management, a holistic approach is needed that semantically connects the three realms by incorporation of human behavior and knowledge. Combining research on knowledge management and computer science, this paper presents a novel meta-framework as socio-technical hybrid simulation language to generalize integration of simulations, gaming and data for modeling urban transportation.

  • 122874. Zomer, Lara-Britt
    et al.
    Moustaid, Elhabib
    KTH, Skolan för teknik och hälsa (STH), Hälso- och systemvetenskap, Vårdlogistik.
    Meijer, Sebastiaan
    KTH, Skolan för teknik och hälsa (STH), Hälso- och systemvetenskap, Vårdlogistik.
    A Meta-Model for Including Social Behavior and Data into Simulation in the Smart City Context2015Ingår i: Proceedings of the 2015 Winter Simulation Conference / [ed] L. Yilmaz, W. K. V. Chan, I. Moon, T. M. K. Roeder, C. Macal, and M. D. Rossetti, 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    mart city management can be regarded to bridge different realms of thinking about cities, i.e., 1) the city as complex-adaptive system, 2) socio-technical operational control center and 3) multi-actor policy-making. Underpinned by different world views and theoretical bodies, integration of the three realms puts forward new demands on simulation approaches and challenges current knowledge and available technology regarding integration of sub-models across different systems. In order to support urban transportation management, a holistic approach is needed that semantically connects the three realms by incorporation of human behavior and knowledge. Combining research on knowledge management and computer science, this paper presents a novel meta-framework as socio-technical hybrid simulation language to generalize integration of simulations, gaming and data for modeling urban transportation.

  • 122875.
    Zong, Jianing
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Shi, Yi
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Kartläggning av databehov inom Scania Motortillverkning2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I dagens samhälle befinner sig tillverkningstekniksindustrin i en övergångsfas på väg in i en digital era. Till skillnad från Industry 3.0 som involverar automatisering av enstaka maskiner och processer omfattar Industry 4.0 digitalisering och uppkoppling av alla aktiviteter i sin värdekedja. Mängden av tillgängliga data ökar hela tiden. Målet med detta examensarbete var att ta reda på vad digitalisering kan tillföra till Scanias motortillverkning med fokus på förbättring av nuvarande KPI:er (Key Performance Indicator). För att säkerställa att det ovanstående målet uppfylls formulerades nedanstående frågeställningar:

    • Hur kan Scania Motortillverkning förbättra KPI i bearbetningsprocesser genom insamling och analys av data från maskiner?

    o Vilka faktorer påverkar Scanias nuvarande KPI?

    o Vilka av dem har potential att utvecklas vidare eller styras genom införande av digitalisering?

    o Vilka maskindata är nödvändiga att samlas in för att öka KPI:er och på vilket sätt kan data samlas in?

    För att besvara frågorna och identifiera vilka data som kan tillföra nytta, användes främst kvalitativa metoder. Data samlades in från olika aspekter av genom praktik, observationer, intervjuer och studiebesök. För att kunna dra generella slutsatser och för att bekräfta hypoteser från de kvalitativa studierna utfördes även en kvantitativ studie som utförs på vevstakeline, genom sortering och analys av de befintliga insamlade data i dagens produktion.

    Efter en litteraturstudie kombinerad med intern informationssamling, kunde fokusområdet avgränsas ytterligare till OPE (Overall Production Effectiveness) som är väsentlig för produktiviteten och ofta inte når målvärdet i nuläget. Genom en analys av PUS (Produktionsuppföljningssystem) kunde faktorer som har en negativ inverkan på OPE tas fram. Genom intervjuer med olika funktioner inom Scania kunde författarna identifiera många konkreta parametrar, vilka kan fördelas till tre kategorier, Maskindata, Verktygdata och Processdata. En teknisk skanning av verktygs- och maskintillverkare genomfördes också för att kunna redogöra för vilka data som är möjliga att samla in med befintliga insamlingsmetoder. 

    Resultatet från detta examensarbetet bildar en utgångspunkt för att kunna digitalisera Scanias motorbearbetning, digitaliseringen kräver en del nya investeringar som författarna anser komma att löna sig på många plan. 

  • 122876. Zong, N. C.
    et al.
    Li, H.
    Lam, M. P. Y.
    Jimenez, R. C.
    Kim, C. S.
    Deng, N.
    Kim, A. K.
    Choi, J. H.
    Zelaya, I.
    Liem, D.
    Meyer, D.
    Odeberg, Jacob
    KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Fang, C.
    Lu, H. -J
    Xu, T.
    Weiss, J.
    Duan, H.
    Uhlén, Mathias
    KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Yates III, J. R.
    Apweiler, R.
    Ge, J.
    Hermjakob, H.
    Ping, P.
    Integration of cardiac proteome biology and medicine by a specialized knowledgebase2013Ingår i: Circulation Research, ISSN 0009-7330, E-ISSN 1524-4571, Vol. 113, nr 9, s. 1043-1053Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Rationale: Omics sciences enable a systems-level perspective in characterizing cardiovascular biology. Integration of diverse proteomics data via a computational strategy will catalyze the assembly of contextualized knowledge, foster discoveries through multidisciplinary investigations, and minimize unnecessary redundancy in research efforts. Objective: The goal of this project is to develop a consolidated cardiac proteome knowledgebase with novel bioinformatics pipeline and Web portals, thereby serving as a new resource to advance cardiovascular biology and medicine. Methods and results: We created Cardiac Organellar Protein Atlas Knowledgebase (COPaKB; www.HeartProteome.org), a centralized platform of high-quality cardiac proteomic data, bioinformatics tools, and relevant cardiovascular phenotypes. Currently, COPaKB features 8 organellar modules, comprising 4203 LC-MS/MS experiments from human, mouse, drosophila, and Caenorhabditis elegans, as well as expression images of 10 924 proteins in human myocardium. In addition, the Java-coded bioinformatics tools provided by COPaKB enable cardiovascular investigators in all disciplines to retrieve and analyze pertinent organellar protein properties of interest. Conclusions: COPaKB provides an innovative and interactive resource that connects research interests with the new biological discoveries in protein sciences. With an array of intuitive tools in this unified Web server, nonproteomics investigators can conveniently collaborate with proteomics specialists to dissect the molecular signatures of cardiovascular phenotypes.

  • 122877. Zong, Xu
    et al.
    Na, Yong
    Wen, Fuyu
    Ma, Guijun
    Yang, Jinhui
    Wang, Donge
    Ma, Yi
    Wang, Mei
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Li, Can
    Visible light driven H-2 production in molecular systems employing colloidal MoS2 nanoparticles as catalyst2009Ingår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, nr 30, s. 4536-4538Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Colloidal MoS2 nanoparticles with diameters of less than 10 nm were prepared with a simple solvothermal method and demonstrated high efficiency in catalyzing H-2 evolution in Ru(bpy)(3)(2+)-based molecular systems under visible light.

  • 122878.
    Zorbas, Dimitros
    et al.
    University of Piraeus.
    Douligeris, Christos
    University of Piraeus.
    Fodor, Viktoria
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Target location based sink positioning in wireless sensor networks2011Ingår i: 2011 18th International Conference on Telecommunications, ICT 2011, 2011, s. 21-26Konferensbidrag (Refereegranskat)
    Abstract [en]

    One of the main challenges in wireless sensor networks is to prolong the network lifetime by efficiently handling the limited battery life of the nodes. This problem becomes harder in applications where the nodes are randomly dropped in the field. In this paper we deal with the problem of the sink placement and of the network longevity, assuming a number of points in the field with known positions which must be covered by the sensors. Unlike other approaches, we consider the more realistic scenario where the coordinates of the sensors are not assumed to be known in advance and, thus, they cannot be used for the computation of the positions of the sinks. We present two solutions for the above problem; one based on the distance between the points and the second on the probability that a sensor may cover many points. We evaluate our approaches and compare them to algorithms that use the knowledge of the positions of the sensors in order to compute likely sink locations. It is shown that both proposed approaches present similar or better performance concerning network lifetime, while at the same time they significantly decrease the algorithm complexity.

  • 122879.
    Zorita, Julio
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Dynamics of small satellites with gravity gradient attitude control2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    SWIM (Space Weather using Ion Spectrometers and Magnetometers) is a CubeSat to be launched with the purpose of studying interaction between the Sun and the Earth. A magnetometer will be placed in a boom which provides gravity gradient stabilization. SWIM will be inserted in a 600 km circular orbit and it is required to maintain a LVLH (Local Vertical Local Horizontal) position. This master thesis analyses the dynamical behavior of SWIM. For doing so an attitude simulator and a mass model have been developed. Mass model has been designed according to linear stability analysis. Simulations with the mass model have been carried out from the most ideal environment to realistic orbit. As a result it has been deduced that gravity gradient stabilization propagates initial conditions which are perturbed by aerodynamic and magnetic torques. Magnetic torques could lead to uncontrolled yaw spin. Additionally the deployment of two solar panels to guarantee passive stabilization for yaw axes has been studied. Three axes stabilization and LVLH pointing can be achieved in an orbit lower than 600 km.

  • 122880. Zorn, Anna-Marie
    et al.
    Malkoch, Michael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Carlmark Malkoch, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Barner-Kowollik, Christopher
    High temperature synthesis of vinyl terminated polymers based on dendronized acrylates: a detailed product analysis study2011Ingår i: POLYMER CHEMISTRY, ISSN 1759-9954, Vol. 2, nr 5, s. 1163-1173Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The combination of dendrons and high temperature acrylate polymerization represents a viable route to form dendronized macromonomers. Dendronized acrylates based on 2,2-bis(hydroxymethyl) propionic acid (bis-MPA) were synthesized using dendrimer synthesis and click chemistry (copper catalyzed azide alkyne cycloaddition (CuAAC)). The synthesis was carried out up to the 3rd generation and with a carbon spacer length of 6 or 9 between the acrylic function and the dendron core. These dendronized acrylates were subjected to auto-initiated high temperature acrylate polymerization. The polymerization was performed at 140 degrees C in a 5 wt% solution of hexyl acetate with a 2,2'-azobis(isobutyronitrile) (AIBN) concentration of 5 x 10(-3) g mol(-1). The vinyl terminated polymers were in-depth characterized via size exclusion chromatography (SEC) and size exclusion chromatography coupled to electrospray ionization mass spectrometry (SEC-ESI-MS) to assess the generated product spectrum and the efficiency of the process. The achievable number average molecular weight, M-n, was between 1700 and 4400 g mol(-1). The degree of polymerization, DPn, decreases with increasing generations of the dendronized acrylates from 6.3 to 3.4. The purity of vinyl terminated oligomers containing a geminal double bond is up to 83%, with the dendronized acrylates of the 1st generation providing the best result. Moderate deprotection of the acetonide groups occurred spontaneously during the macromonomer formation process and reached its maximum at generation 3.

  • 122881. Zou, Bin
    et al.
    Li, Zong-Liang
    Song, Xiu-Neng
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Wang, Chuan-Kui
    Effects of field-induced geometry relaxation on the electron transport properties of 4,4'-biphenyldithiol molecular junction2007Ingår i: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 447, nr 03-jan, s. 69-73Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The non-linear charge transport properties of 4,4 '-biphenyldithiol molecular junction have been studied using the generalized Green's function theory. It is shown that the torsion angle between two phenyls is slightly decreased as increase of the external voltage while the whole molecule moves slightly along the reversed direction of the electric field. Calculations indicate that the inclusion of molecular geometry relaxation can avoid a false prediction of negative differential resistance behavior. The charge redistribution under the external bias results in resistive dipoles inside the molecule. The calculated I-V curves of 4,4 '-biphenyldithiol molecular junction is consistent with experimental observations in some ways.

  • 122882.
    Zou, Dapeng
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Andersson, Samir
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Zhang, Rong
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Sun, Shiguo
    Åkermark, Björn
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Selective binding of cucurbit 7 uril and beta-cyclodextrin with a redox-active molecular triad Ru(bpy)(3)-MV2+-naphthol2007Ingår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, nr 45, s. 4734-4736Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A 1:1:1 inclusion complex is formed by the binding interactions among beta-CD, CB[ 7] hosts, and Ru(bpy)(3)-terminated viologen naphthalene guest in aqueous solution, in which the positions of both CB[7] and beta-CD are closer to the Ru stopper than in the respective 1:1 inclusion complexes, forming a tightened nut on bolt'' structural mode.

  • 122883.
    Zou, Dapeng
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Andersson, Samir
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Zhang, Rong
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Sun, Shiguo
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Åkerrnark, Björn
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    A host-induced intramolecular charge-transfer complex and light-driven radical cation formation of a molecular triad with cucurbit 8 uril2008Ingår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 73, nr 10, s. 3775-3783Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The host-guest chemistry of systems containing a molecular triad Ru(bpy)(3)-MV2+-naphthol complex (denoted as Ru2+-MV2+-Np, 1) and cucurbit[8]uril (CB[8]) is investigated by NMR, EST-MS, UV-vis, and electrochemistry. The Ru2+-MV2+-Np guest and CB [8] host can form a stable 1:1 inclusion complex, in which the naphthalene residue is back-folded and inserted together with the viologen residue into the cavity of CB[8]. The selective binding of Ru2+-MV2+-Np guest with beta-CD and CB[8] host is also investigated. We find that CB[8] binds the Ru2+-MV2+-Np guest stronger than beta-CD. Upon light irradiation, a MV+center dot radical cation stabilized in the cavity of CB[8] accompanied by the naphthalene residue has been observed. This novel system may open a new way for design and synthesis of photoactive molecular devices.

  • 122884.
    Zou, Feng
    KTH, Tidigare Institutioner                               , Materialvetenskap.
    Localized electrochemical impedance technique for the study of corrosion processes1998Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    A localized electrochemical impedance technique has beendeveloped based on a measure of the local a.c. potentialgradient in solution by a high-resolution probe. The probeconsists of a pair of microelectrodes or a single vibratingmicroelectrode with a tip size of about 10 mm. Compared withthe experimental set-up using the bielectrode probe, the set-upusing the single vibrating-electrode probe has a highersensitivity and can be used in very low frequency range, butthe measurements by this set-up are more complex.

    Some aspects of this technique are also discussed in thethesis. The measured local a.c. potential gradient in solutionmay be related not only to the local a.c. surface currentdensity at the same location by simply using Ohm’s law asdescribed in the literature but also to the convolutionintegral of the a.c. surface current density distribution. Inorder correctly to interpret the surface current distribution,a deconvolution of the measured potential differencedistribution is necessary. The deconvolution using thebase-line stripping procedure and the Fourier Transform methodhas been investigated. The results showed that a more accuratesurface current density distribution could be obtained by thedeconvolution of the measured potential gradient distribution.In order to achieve a higher spatial resolution, the probe isnormally located as close as possible to the surface of thespecimen. However, when the probe is placed very close to thesurface, e.g. within the diffusion layer, the measurement maybe influenced by the heterogeneous distribution of ionicspecies in this range of the solution. This influence has alsobeen demonstrated and simulated. It is found that the influencecan be d.c. current-dependent when the influence ispredominately due to the variation of solution conductivity orless d.c. current-dependent when the influence is predominatelydue to the redox potential difference at different locations inthe solution. It is also noted that the influence is morepronounced in the low frequency range than in the highfrequency range.

    The technique has been used to study the pitting corrosionof Fe-Cr alloys and the degradation of organic coatings. Theresults indicate that this technique can be used not only toinvestigate the heterogeneities over the surface of a specimenwhich may be related to the localized attack, but also toobtain information about the mechanism of the localizedcorrosion by positioning the probe at the interested locationand recording the localized impedance as a function offrequency.

    Key words: corrosion, micro-electrode, electrochemicalimpedance, localized impedance technique, localized corrosion,pitting corrosion, coatings, deconvolution, diffusion.

  • 122885. Zou, H.
    et al.
    Kleiven, Svein
    KTH, Skolan för teknik och hälsa (STH), Neuronik.
    Schmiedelera, J. P.
    The effect of brain mass and moment of inertia on relative brain-skull displacement during low-severity impacts2007Ingår i: International Journal of Crashworthiness, ISSN 1358-8265, E-ISSN 1754-2111, Vol. 12, nr 4, s. 341-353Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Traumatic brain injury is the leading cause of death in automobile crashes. The sensitivity of human brain injury prediction to small parameter changes is a critical element of both experimental and mathematical work yet to be adequately investigated. This work proposes a new analytical human brain injury model to determine the parameters to which injury prediction is most sensitive. The trajectory sensitivity analysis explicitly indicates that injury prediction is most sensitive to brain mass moment of inertia, followed by brain mass. A number of finite element (FE) simulations were executed with various brain sizes. The maximum relative brain motions decrease with decreased brain size, and they are very close in the FE and analytical models. We conclude that brain mass moment of inertia, primarily, and brain mass, secondarily, should be varied in focused experimental and FE modeling work to ensure that conclusions are not drawn from individual data points at which injury predictions are highly sensitive to small parameter changes.

  • 122886.
    Zou, Hong
    et al.
    Department of Mechanical Engineering, The Ohio State University.
    Kleiven, Svein
    KTH, Skolan för teknik och hälsa (STH), Neuronik.
    Schmiedeler, James P.
    Department of Mechanical Engineering, The Ohio State University.
    The Effect of Brain Mass and Moment of Inertia on Relative Brain-Skull Displacement in Low-Severity Impacts2006Konferensbidrag (Refereegranskat)
  • 122887.
    Zou, Kai
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Construction Methods: An International Survey of Construction Methods for Bridge Foundations2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Bridges have become an important and common part of the infrastructure worldwide. It has been estimated that the cost of the bridge foundation construction constitutes 30% to 50% of the total bridge cost. Thus efficient and cost-saving construction methods are vital for the construction industry and for the society. For this purpose this report includes an international study of 30 bridges and their foundations, the goal of which tries to identify efficient and cost saving methods for bridge foundations.

    Ten case studies from each of North America, Europe and Asia have been included in the report including both piled (deep foundation methods) and spread footing methods.

    Large span bridges like cable-stayed bridges and suspension bridges as well as small span bridge have been included in the study. Because of the increasing popularity, special attention has been paid to the so-called integral bridge type. The case studies contain some general information about the bridge, the geological conditions at the bridge site and a brief description of the foundation methods used.

    The trend of using BIM in preliminary and detailed design of bridges is discussed in a separate section of the report. Possible advantages for adopting BIM in the design of bridge foundations such as interactive design processes are discussed.

    Bridge foundations may have a significant environmental impact including large excavations, hazardous materials, noise and etc. The important environmental impact in connection with the foundation work has been commented in another separate section called life cycle assessment.

    Finally the case studies are discussed in the conclusions section. The study, being very limited compared to the numerous bridges being built in the world, anyway gives an insight in the big challenges that are associated with bridge foundations and hopefully may give inspiration to new and efficient ways for the foundation of bridges in the future.

  • 122888. Zou, L.
    et al.
    Frampton, A.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Impacts of dead-ends on flow and transport in fractured rocks2018Ingår i: 2nd International Discrete Fracture Network Engineering Conference, DFNE 2018, American Rock Mechanics Association (ARMA) , 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Detailed simulation of flow and transport through a rough-walled fracture-matrix system with fracture dead-ends is performed. The analysis demonstrates a significant impact of fracture dead-ends on fluid flow and solute transport processes in the modelled system. Two 2D representative rock fracture-matrix models with and without fracture dead-ends are constructed based on high-resolution laser-scanned measurements of a granite rock fracture surface. Simulations of flow and transport with three Péclet numbers (Pe) ranging from 0.1 to 10 are conducted using a code implementing the finite volume method (FVM) to solve the Navier-Stokes equations (NSE) for water flow in the fracture, and the advection-diffusion equation (ADE) is adopted to solve for transport in the whole fracture-matrix system, also accounting for matrix diffusion. The features of the velocity fields and evolution of concentration distributions as well as breakthrough curves of the two modelled cases are presented and analyzed, with results showing that fracture dead-ends significantly affect solute transport processes and cause important retardation of transport in the fracture. This indicates that overly conservative assessments of solute mass arrivals may be made when fracture dead-ends are ignored in discrete fracture network modelling.

  • 122889.
    Zou, Liangchao
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Numerical modeling of fluid flow and solute transport in rock fractures2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Denna studie fokuserar på numerisk modellering av vätskeflöde och transport av lösta ämnen i frakturer med ojämna väggar samt fraktur-matrissystem, med det huvudsakliga syftet att undersöka effekterna av frakturernas ytjämnhet på flödes- och transportprocesser i bergsfrakturer. Både 2D och 3D modeller skapades utifrån laser skannad tomografi av ett verkligt bergartsprov av granit, för att överväga de realistiska egenskaperna hos ytan och potentiell skrovlighet. Flödet simulerades genom att lösa Navier-Stokes ekvationer (NSE) och transporten modellerades genom att lösa advektion-dispersion ekvation (ADE) i hela domänen av fraktur-matrissystemet, inklusive diffusions process i matrisen. Sådana direkta simuleringar resulterade i detaljerade flödes- och koncentrationsfält för att kvantitativt kunna analysera flödet och transportbeteendet. En detaljerad analys av upplösningen av ytjämnhet, komplexa flödesmönster (dvs kanalisering, tvärgående och virvelströmmar), effektiv advektiv flödesöppning, effektiv transmissivitet, effektiv dispersivitet, uppehållstid, transport motstånd och specifik yta visade signifikanta effekter av realistiska ojämna frakturväggar på vätskeflöde och lösta transportprocesser i bergssprickor. Resultaten visar att ytjämnhet och skjuvningssystemsorsakade asperitetskontakter avsevärt förbättrar olinjäritet och komplexitet av flödes- och transportprocesser i frakturer med ojämna väggar samt fraktur-matrissystem. Ytråheten orsakar också intrång av flöde i tvärgående frakturer vilket ökar blandingen av lösta ämnen i korsningarna. Därför är ytjämnhet av frakturerna en viktig källa till osäkerhet i tillämpningen av sådana förenklade modeller som kubisk lag (CL) för vätskeflöde och analytiska lösningar för transport av lösta ämnen i bergsfrakturer. Studien har ökat förståelsen för realistiska flödes- och transportprocesser i naturligt sprucket berg. Resultaten är användbara för modellvalidering/förlängning, osäkerhetsanalys/kvantifiering och design av laboratorieexperiment i samband med olika tillämpningar av flöde och transport i bergsfrakturer.

  • 122890.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik. KTH.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik. KTH.
    Modeling of advection-dominated transport in rough-walled rock fractures: a comparison of Reynolds and Navier-Stokes equationsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Statistical analysis of flow-dependent specific surface areas of a 3D rough-walled fracture-matrix system were presented in this paper, based on numerical simulations of fluid flow and advective particle transport. The aim is to investigate the flow-dependent solute transport quantities in natural fracture-matrix systems, and identify the potential uncertainty lie in the common used flow model (i.e., Reynolds equation) by comparing with the more realistic flow model(i.e., Navier-Stokes equations). The rough-walled fracture model was built from laser-scanned surface tomography of a real rock sample, by considering realistic features of surfaces roughness and asperity contacts. Based on the flow fields simulated by solving the Reynolds and Navier-Stokes equations, the advective transport was modeled through Lagrangian particle tracking. The controlling quantities of advective transport in fracture-matrix systems (i.e., residence time, transport resistance and specific surface area) were statistically analyzed and compared. The results generally show that fracture surface roughness and associated spatially variable apertures as well as shear caused asperity contacts significantly increase the heterogeneity of flow field in rough-walled fractures, which consequently affects the flow-dependent transport process. By comparison, the simplified flow model (i.e., Reynolds equation) may cause uncertainty in quantifying of the specific surface area for the realistic rough-walled fracture-matrix systems. To identify such uncertainty, it is important to obtain the more reliable flow fields by solving the NSE. The presented results are helpful in uncertainty quantification and risk assessment of solute transport in natural fractured rocks.

  • 122891.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Roughness decomposition and effects on fluid flow in single rock fractures2014Ingår i: ISRM International Symposium - 8th Asian Rock Mechanics Symposium, ARMS 2014, International Society for Rock Mechanics , 2014, s. 457-465Konferensbidrag (Refereegranskat)
    Abstract [en]

    The rock fractures usually consist of surfaces with different orders or scales of roughness, which have critical effects on the fluid flow behavior inside the fractures. In this paper, a two dimensional representative single rock fracture model was built, based on a laser scanned data of rock surface of granite. The surfaces roughness of the fracture was then quantitively decomposed into several levels of surface roughness by applying the wavelet analysis. A self-developed Finite Volume Method solver was then applied to solve the Navier-Stokes equations for numerical modelling of fluid flow in the fracture models formatted with four levels of decomposed roughness, respectively, with different Reynolds numbers varying from 0.001 to 1000.0. Then, the features of velocity profiles and the effective hydraulic apertures at each level of rough fractures decomposition and Reynolds numbers were calculated and analyzed. The results show that when the Reynolds number is small (less than 10.0), the effective hydraulic aperture slightly increase nearly linearly with the decomposed roughness levels. When the Reynolds number is large, the effective hydraulic apertures decrease dramatically, and the non-linear flow behaviors represented by expansion of the eddy flow regions caused by roughness: The larger extent of high-frequency roughness, the more obvious and complicate eddy flow regions yielded.

  • 122892.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Håkansson, U.
    KTH.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Impacts of elastic jacking on rock grouting2018Ingår i: ISRM International Symposium - 10th Asian Rock Mechanics Symposium, ARMS 2018, International Society for Rock Mechanics , 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    The injection pressure is an important design and operational parameter in rock grouting since it controls the grout penetration length and may cause harmful mechanical deformation of the rock mass, such as opening/dilation of the fractures, referred to as jacking. At present, modeling of rock grouting mainly relies on analytical models where the impact of jacking on the grout penetration in rock fractures is not considered. In this study, we present a hydro-mechanical coupled model for rock grouting in a single one-dimensional rock fracture, with consideration of jacking and two-phase flow, i.e. cement grout and groundwater. It assumes that the cement grouts are Bingham fluids and that the rock matrix is an elastic material. The fracture is simplified as a pair of smooth parallel plates. A finite element method (FEM) code is developed to iteratively solve the two-phase flow in the fracture and the elastic deformation of the rock matrix. Two cases with and without consideration of jacking are simulated and compared. The results generally show that jacking of fractures significantly affects the grout penetration in the fracture, which should be properly considered in modeling of rock grouting. This numerical model is able to describe more realistic physical processes in rock grouting, which can be used to estimate the optimal injection pressure in practice. 

  • 122893.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Håkansson, Ulf
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Cement grout propagation in two-dimensional fracture networks: Impact of structure and hydraulic variability2019Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 115, s. 1-10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Analysis of cement grout propagation in water-saturated two-dimensional discrete fracture networks is presented in this study. A two-phase flow model for Bingham fluids flow in a single saturated fracture is extended to simulate cement grouts propagation in saturated networks. Using this extended model, the impacts of network structure and hydraulic variability, i.e., network geometry and aperture distribution, on the propagation process are investigated through numerical simulations. Cement grout propagation in 50 realizations of a two-dimensional discrete fracture network (2D DFN) are simulated with different cases of aperture variability, i.e. constant aperture, uncorrelated and length-correlated heterogeneous apertures following a truncated lognormal distribution. The results indicate that network structure and hydraulic variability significantly affect the grout propagation in 2D DFN systems. The randomized network structure and uncorrelated heterogeneous apertures significantly delay the propagation rate and largely increase the variability range of the propagation volume fraction. In contrast, in the case with length-correlated heterogeneous apertures, the propagation rate increases, while the variability range and rate of change of the propagation volume fraction decreases. The extended two-phase flow model for fracture networks and the simulation results presented in this work are useful for basic understanding of the processes relevant for design, monitoring and execution of rock grouting.

  • 122894.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Håkansson, Ulf
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Modeling of rock grouting in saturated variable aperture fractures2018Ingår i: Proceedings of Bergdagarna 2018., 2018, s. 79-87, artikel-id 10Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Modellering och analys av cementbaserade injekteringsmedels strömning är viktiga hjälpmedel för design, utförande och uppföljning av injektering i sprickigt berg. Dagens modeller är ofta baserade på förenklade analytiska lösningar, exempelvis de som ingår i ”Real time grouting control (RTGC)” metoden. För att analytiska lösningar skall kunna användas, antas att sprickorna utgörs av släta, plan-parallella skivor och att dessa inte innehåller något vatten. I verkligheten är dock sprickorna råa, vattenfyllda och med komplexa geometrier, vilket medför att cementinjektering i sprickigt berg i strikt mening är en multi-fas process i en varierande geometri. I föreliggande studie, presenteras en en-dimesionell numerisk model för injektering i en enskild spricka, under beaktande av multi-fas strömning med varierande spricköppning. En tidsberoende advektionsfunktion används för att beskriva gränsskiktet mellan injekteringsmedel och vatten och dess förflyttning med tiden. Resultaten visar på en betydande påverkan från sprickornas vatteninnehåll, dels på tryckfördelningen men även på injekteringsmedlets inträngning i sprickorna, särskilt vid låg viskositet. Den varierande spricköppningen gör också att inträngningen blir långsammare i förhållande till fallet med en konstant spricköppning, vilket är förväntat. Den numeriska modellen beskriver förhållandena på ett mer realistiskt sätt, både ur fysikalisk och geometrisk synvinkel, vilket kan utnyttjas i praktiken för att reducera potentiella osäkerheter vid användandet av dagens analytiska metoder.

  • 122895.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Håkansson, Ulf
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik. Skanska AB .
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Non-Newtonian grout flow in single rough-walled rock fractures2019Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Modellering av cement-baserade injekteringsmedels strömning i bergsprickor spelar en viktig roll för prediktion och design. De medel som används vid injektering är typiskt icke- Newtonska, med en flytgräns, och antas därför vara av Bingham typ. Naturliga bergsprickor har vanligtvis en rå och ojämn yta. Analyser av injekteringsförlopp borde därför innehålla både icke-Newtonska vätskor och råhet hos sprickorna, vilket oftast inte är fallet i den litteratur som finns tillgänglig idag. I föreliggande arbete fokuseras på inverkan av bergsprickors råhet och numeriska beräkningar redovisas för icke-Newtonska injekteringsmedels strömning i enskilda sprickor, med hjälp av en regulariserad metod för hantering av brukets flytgräns. Sprickytornas råhet modelleras från laser-scannade ytor av granitprover för att erhålla så realistiska förhållanden som möjligt. Resultaten visar på icke-linjära effekter och att de råa sprickytorna har en avgörande inverkan på spricktransmissiviteten och att resultaten kan användas för att minska osäkerheten vid praktisk tillämpning.

    Publikationen är tillgänglig i fulltext från 2020-01-01 23:22
  • 122896.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Håkansson, Ulf
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Two-phase cement grout propagation in homogeneous water-saturated rock fractures2018Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 106, s. 243-249Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Modeling of cement grout flow in rock fractures is important for the design, monitoring and execution of rock grouting that is widely used in a variety of rock engineering applications. This study presents a mathematical model based on the Reynolds flow equation for cement grout flow in a homogeneous water-saturated rock fracture. The model is based on two-phase flow, i.e. grout as a Bingham fluid and groundwater as a Newtonian fluid, and is used for investigating the importance of the water phase in rock grouting. The modeling results for the two-phase flow generally show the importance of the water phase that can significantly affect the pressure distribution and grout penetration in the fracture, especially under the condition of grout hardening. Such effects depend on the viscosity ratio between the grout and groundwater, which becomes increasingly important for cases with smaller values of the viscosity ratio. The grout density also affects the grout penetration length. Applying an analytical solution based on single-phase flow, i.e. neglecting the impact of groundwater flow, for modeling grout injection, will generally overestimate the penetration length.

  • 122897.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Smoothed particle hydrodynamics simulation of fluid flow in rock fractures2013Ingår i: Rock Characterisation, Modelling and Engineering Design Methods: Proceedings of the 3rd ISRM SINOROCK 2013 Symposium, 2013, s. 437-443Konferensbidrag (Refereegranskat)
    Abstract [en]

    The process of fluid flow in rock fractures involves complicated dynamical behavior of fluids,and its modeling is a challenge to numerical methods. In this paper, the Smoothed Particle Hydrodynamics(SPH), a particle method based on Lagrangian formulation, is employed to simulate the fluid flow in rockfractures by solving the Navier-Stokes equations directly. Firstly, the SPH method and the boundary treatmentmethod used in this simulation were introduced and the computer code of SPH was developed and validated bya series of numerical benchmark tests with analytical solutions. Then simulations were carried out to investigatethe fluid flow both in single fractures and intersected fractures, with and without considering effects of surfaceroughness. The results of the simulations are discussed and compared with the analytical solution by using theCubic law derived from the Reynolds equation. The results show that in both of rough single fractures andfracture intersections, although the relationship between mean velocity and the Reynolds number is still linear,the solutions by using Cubic law overestimated the mean fluid velocity with increasing the Reynolds number,indicating possible underestimate of travel time of mass transport in the fracture network models.

  • 122898.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Assumptions of the analytical solution for solute transport in a fracture-matrix system2016Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 83, s. 211-217Artikel i tidskrift (Refereegranskat)
  • 122899.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Effect of sorption on solute transport in a single rough rock fracture2017Ingår i: 13th ISRM International Congress of Rock Mechanics, International Society for Rock Mechanics , 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Sorption process plays a significant role for solute retardation in rock fractures. In this paper, for the aim to investigate the effect of sorption on solute transport in a single rough fracture, a 2D model of representative single rock fracture was built and its roughness was statistically characterized based on the measured data of rock surface topography by laser scanning. A Finite Volume Method (FVM) code was developed to solve the Navier-Stokes (NS) equations and transport equation for numerical modelling the process of fluid flow and solute transport in the rock fracture model. Two groups of simulations were conducted: with and without the consideration of the sorption process with different average flow velocities. The results show that the surface roughness increased the complexities of flow fields, and the non-linear sorption process plays a significant role in the retardation of solute transport through rock fractures. The sorption process caused an obvious lagging time in both the solute concentration fields (plumes) and corresponding breakthrough curves. This lagging time increases with the distance from the inlet boundary, and relatively decreases with the increase of mean velocities.

  • 122900.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Effects of multi-level surface roughness on solute transport in single rock fractures2016Ingår i: The proceeding of International Symposium on Reducing Risks in Site Investigation, Modeling and Construction for Rock Engineering, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    Natural rock fractures are consisted of complicate rough surfaces with multi-level surface roughness which causes significant uncertainties in fluid flow and solute transport be-haviors through fractured rocks. In this study, for the aim of investigation the effects of multi-level surface roughness on fluid flow and solute transport in rock fractures, a single rough-walled fracture model was built from a scanned granite rock surface, which was then gradually decomposed and characterized by wavelet analysis and statistics. A verified finite volume method (FVM) code was used to simulate fluid flow and solute transport in the rough fracture models by solving the Navier-Stokes equations (NSE) and advection-dispersion equation (ADE). The simulation results of nonlinear flow and solute breakthrough curves (BTCs) showed that the multi-level surface roughness strongly correlated with the Eddy flows and the solute non-Fickian transport behaviors, represented by the changes of effective advective flow apertures and an empirical function of the BTCs. The results would improve our understanding of solute transport in fractured rocks and may help to reduce the uncertainties and risks in related engi-neering practices.

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