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  • 126651. Zelenina, M.
    et al.
    Zelenin, S.
    Bondar, A. A.
    Brismar, Hjalmar
    Aperia, A.
    Water permeability of aquaporin-4 is decreased by protein kinase C and dopamine2002In: American Journal of Physiology - Renal Physiology, ISSN 0363-6127, E-ISSN 1522-1466, Vol. 283, no 2, p. F309-F318Article in journal (Refereed)
    Abstract [en]

    Aquaporin-4 (AQP4) plays an important role in the basolateral movement of water in the collecting duct. Here we show that this water channel can be dynamically regulated. Water permeability (P-f) was measured in individual LLC-PK1 cells that were transiently transfected with AQP4. To identify which cells were transfected, AQP4 was tagged at the NH2 terminus with green fluorescent protein. Transfected cells showed a strong fluorescent signal in basolateral membrane and a low-to-negligible signal in the cytosol and apical membrane. Activation of protein kinase C (PKC) with phorbol 12,13-dibutyrate (PDBu) significantly decreased P-f of cells expressing AQP4 but had no effect on neighboring untransfected cells. No redistribution of AQP4 in response to PDBu was detected. Dopamine also decreased the P-f in transfected cells. The effect was abolished by the PKC inhibitor Ro 31-8220. Reduction of AQP4 water permeability by PDBu and dopamine was abolished by point mutation of Ser(180), a consensus site for PKC phosphorylation. We conclude that PKC and dopamine decrease AQP4 water permeability via phosphorylation at Ser(180) and that the effect is likely mediated by gating of the channel.

  • 126652.
    Zelenina, Marina
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Regulation of brain aquaporins2010In: Neurochemistry International, ISSN 0197-0186, E-ISSN 1872-9754, Vol. 57, no 4, p. 468-488Article in journal (Refereed)
    Abstract [en]

    Three aquaporins are expressed in the brain. AQP4, the predominant brain water channel, is expressed in astrocyte endfeet facing brain capillaries, perisynaptic spaces, and nodes of Ranvier. It is implicated in brain edema formation and resolution. It is also believed to assist clearance of K+. released during neuronal activity. AQP1 is expressed in epithelial cells of choroid plexus and is implicated in cerebrospinal fluid formation. AQP9, which has been reported to be present in astrocytes and in subpopulations of neurons, is implicated in the brain energy metabolism. All three brain AQPs are strongly upregulated in brain tumors and in injured brain tissue. Water and solute transport via AQPs depends on concentration gradients across the membrane, but the magnitude of the transport is to a large extent determined by the single channel permeability of AQPs and by their abundance in the cell membrane. The future therapies will have to address not only the forces driving the water and solute transport (e.g. as mannitol infusion does in the treatment of brain edema), but also the regulation of AQPs, which provide the means for water entry to the brain, for water exit from the brain, and for redistribution of water and solutes within the brain compartments. This review summarizes the data concerning structure, permeability, role in the brain, short-term and long-term regulation of the three AQPs.

  • 126653.
    Zelenina, Marina
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Bondar, Alexander A
    Zelenin, Sergey
    Aperia, Anita
    Nickel and extracellular acidification inhibit the water permeability of human aquaporin-3 in lung epithelial cells.2003In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 278, no 32, p. 30037-43Article in journal (Refereed)
    Abstract [en]

    Nickel is a common cause of pneumoconiosis. Here, we show that nickel inactivates aquaporin (AQP)-3, the water channel expressed apically in epithelial cells of human terminal airways. Human AQP3 was transiently transfected into human lung cells, and water permeability was measured in transfected and neighboring untransfected cells. Incubation with NiCl2 rapidly, dose-dependently, and reversibly decreased water permeability in AQP3-expressing cells. Acidification of the extracellular medium also caused rapid, dose-dependent, and reversible inhibition of AQP3. Sensitivity of AQP3 to nickel was lower at alkaline pH than at neutral and acidic pH. Cells transfected with human AQP4 and AQP5, which are also expressed in airway epithelia, were insensitive to nickel and extracellular acidification. Zinc and cadmium, other common causes of pneumoconiosis, had no effect on the water permeability of AQP3. Three extracellular residues, Trp128, Ser152, and His241, were responsible for the blocking effect of nickel on human AQP3. Ser152 was identified as a common site for nickel and pH sensitivity. His53, Tyr124, and His154 were also involved in regulation of AQP3 by extracellular pH. In addition, the aromatic side chain of His154 was shown to be important for the water permeability of AQP3. Our results imply that nickel and extracellular pH may modulate lung water clearance and that defective water clearance may be an early component of nickel-induced lung disease.

  • 126654.
    Zelenina, Marina
    et al.
    Nordic Centre of Excellence for Research in Water Imbalance Related Disorders (WIRED), Department of Woman and Child Health, Karolinska Institute.
    Li, Yanhong
    Glorieux, Isabelle
    Arnaud, Catherine
    Cristini, Christelle
    Decramer, Stéphane
    Aperia, Anita
    Casper, Charlotte
    Urinary aquaporin-2 excretion during early human development2006In: Pediatric nephrology (Berlin, West), ISSN 0931-041X, E-ISSN 1432-198X, Vol. 21, no 7, p. 947-952Article in journal (Refereed)
    Abstract [en]

    This study was undertaken to assess one of the determinants of kidney concentrating capacity, aquaporin-2 (AQP2), in order to understand the physiopathology of water balance in newborn babies. Urinary AQP2 excretion has been shown to be proportional to AQP2 level in the apical plasma membrane of the kidney collecting ducts and has been suggested as a marker of vasopressin (AVP) action. Urinary AQP2 excretion in the early postnatal period and at 3 weeks of age was measured in 123 neonates admitted during a 6-month period to the neonatal intensive care unit of the Children's Hospital of Toulouse, France. Clinical and biochemical data were collected for each child. During the first days after birth, higher urinary AQP2 was observed in boys than in girls (P=0.01) and positively correlated with urinary sodium/potassium (Na/K) ratio (r=0.33, P=0.01). When the babies had reached 3 weeks of age, urinary AQP2 was proportional to the gestational age at birth (r=0.33, P=0.0068) and daily weight gain (r=0.36, P=0.003). It did not correlate with urinary osmolality, which was overall very low in all babies. Urinary AQP2 was decreased in conditions of impaired renal function (r=-0.42, P=0.0005) and acidosis (P=0.03). Prenatal corticosteroid treatment had no significant impact on urinary AQP2 level. Our data show that urinary AQP2 correlates with the overall maturity of tubular function in human neonates. In babies at this early age, urinary AQP2 cannot serve as a direct marker of the renal action of AVP but reflects AQP2 expression level associated with different physiopathological conditions.

  • 126655.
    Zelenina, Marina
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Li, Yanhong
    Kamali-Zare, Padideh
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Sakuraba, Shigeki
    MacAulay, Nanna
    Zelenin, Sergey
    Bondar, Alexander
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Aperia, Anita
    A role for AQP4 in renal K+ transportManuscript (preprint) (Other academic)
    Abstract [en]

    The principal cells of the collecting duct carry out two major tasks: concentration of urine and regulation of K+ homeostasis. Two water channels, AQP3 and AQP4, are expressed in the principal cell basolateral membrane. We propose that AQP4 participates in the regulation of K+ transport in the principal cells. K+ enters the cell via Na+, K+-ATPase-mediated transport in the basolateral membrane. The presence of K+ channels in this membrane permits some K+ recirculation, considered important for maintenance of membrane potential. Here we show that AQP4, but not AQP3, assembles with both Na+, K+-ATPase and an inwardly rectifying K+ channel Kir7.1. We hypothesize that AQP4, Na+, K+-ATPase and Kir7.1 form a K+-transporting microdomain and that AQP4 serves to maintain a favorable concentration gradient for K+ efflux into the diffusion-limited space within the deep infoldings in principal cell basal membrane. The hypothesis is tested in a mathematical model. The model predicts that the impact of AQP-mediated water transport on K+ transport is more significant if AQP water permeability is sensitive to fluctuations in extracellular K+ concentration ([K+]e). We measured water permeability of AQP4 expressed in a renal epithelial cell line and found that it is upregulated when [K+]e is increased to 8 mM, and downregulated when [K+]e is decreased to 1 mM. Studies in an oocyte system indicate that AQP4 does not possess a voltage or K+ sensor. Finally, we show that the expression of AQP4 in rat renal medulla is, in contrast to the expression of AQP2 and AQP3, resistant to changes in K+ intake. Our experimental data, together with the mathematical model, support the concept that AQP4 is involved in principal cell K+ transport processes.

  • 126656.
    Zelenina, Marina
    et al.
    Department of Woman and Child Health, Karolinska Institutet.
    Tritto, Simona
    Bondar, Alexander A.
    Zelenin, Sergey
    Aperia, Anita
    Copper inhibits the water and glycerol permeability of aquaporin-32004In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 279, no 50, p. 51939-51943Article in journal (Refereed)
    Abstract [en]

    Aquaporin-3 (AQP3) is an aquaglyceroporin expressed in erythrocytes and several other tissues. Erythrocytes are, together with kidney and liver, the main targets for copper toxicity. Here we report that both water and glycerol permeability of human AQP3 is inhibited by copper. Inhibition is fast, dose-dependent, and reversible. If copper is dissolved in carbonic acid-bicarbonate buffer, the natural buffer system in our body, doses in the range of those observed in Wilson disease and in copper poisoning caused significant inhibition. AQP7, another aquaglyceroporin, was insensitive to copper. Three extracellular amino acid residues, Trp128, Ser152, and His241, were identified as responsible for the effect of copper on AQP3. We have previously shown that Ser152 is involved in regulation of AQP3 by pH. The fact that Ser152 mediates regulation of AQP3 by copper may explain the phenomenon of exquisite sensitivity of human erythrocytes to copper at acidic pH. When AQP3 was co-expressed with another AQP, only glycerol but not water permeability was inhibited by copper. Our results provide a better understanding of processes that occur in severe copper metabolism defects such as Wilson disease and in copper poisoning.

  • 126657.
    Zelenina, Marina
    et al.
    Nordic Ctr. Excellence Res. WIRED, Department of Woman and Child Health, Karolinska Institutet.
    Zelenin, Sergey
    Aperia, Anita
    Water channels (aquaporins) and their role for postnatal adaptation.2005In: Pediatric Research, ISSN 0031-3998, E-ISSN 1530-0447, Vol. 57, no 5 II, p. 47R-53RArticle in journal (Refereed)
    Abstract [en]

    Birth is a transition from an underwater life in the uterus to a terrestrial life in a milieu where supply of water is limited. Rapid adaptation to the new environment is crucial for survival and health of infants. The discovery of a family of molecules-aquaporin (AQP) water channels-that are responsible for regulated water transport across cell membranes has made it possible to identify the molecular mechanisms behind the postnatal homeostatic adaptation and to better understand water imbalance-related disorders in infancy and childhood. Thirteen mammalian AQP isoforms have been identified, most of them having a unique tissue-specific pattern of expression. Most mammalian AQPs can be dynamically regulated, which makes them potential targets for the development of new drugs for diseases associated with disturbances in water homeostasis. This review deals with AQP in kidney, lung, and brain. Evidence is presented that AQPs are expressed in a specific age-dependent manner and that the timed expression of AQPs may have a crucial role during the early postnatal period.

  • 126658.
    Zelezniak, Aleksej
    et al.
    KTH. Francis Crick Inst, Mol Biol Metab Lab, London, England.;Univ Cambridge, Dept Biochem, Cambridge, England.;Univ Cambridge, Cambridge Syst Biol Ctr, Cambridge, England.;Chalmers Univ Technol, Dept Biol & Biol Engn, Gothenburg, Sweden.;KTH Royal Inst Technol, Sci Life Lab, Stockholm, Sweden..
    Vowinckel, Jakob
    Univ Cambridge, Dept Biochem, Cambridge, England.;Univ Cambridge, Cambridge Syst Biol Ctr, Cambridge, England.;Biognosys AG, Schlieren, Switzerland..
    Capuano, Floriana
    Univ Cambridge, Dept Biochem, Cambridge, England.;Univ Cambridge, Cambridge Syst Biol Ctr, Cambridge, England..
    Messner, Christoph B.
    Francis Crick Inst, Mol Biol Metab Lab, London, England..
    Demichev, Vadim
    Francis Crick Inst, Mol Biol Metab Lab, London, England.;Univ Cambridge, Dept Biochem, Cambridge, England.;Univ Cambridge, Cambridge Syst Biol Ctr, Cambridge, England..
    Polowsky, Nicole
    Univ Cambridge, Dept Biochem, Cambridge, England.;Univ Cambridge, Cambridge Syst Biol Ctr, Cambridge, England..
    Mulleder, Michael
    Francis Crick Inst, Mol Biol Metab Lab, London, England.;Univ Cambridge, Dept Biochem, Cambridge, England.;Univ Cambridge, Cambridge Syst Biol Ctr, Cambridge, England..
    Kamrad, Stephan
    Francis Crick Inst, Mol Biol Metab Lab, London, England.;UCL, Dept Genet Evolut & Environm, London, England..
    Klaus, Bernd
    EMBL, Ctr Stat Data Anal, Heidelberg, Germany..
    Keller, Markus A.
    Univ Cambridge, Dept Biochem, Cambridge, England.;Univ Cambridge, Cambridge Syst Biol Ctr, Cambridge, England.;Med Univ Innsbruck, Innsbruck, Austria..
    Ralser, Markus
    Francis Crick Inst, Mol Biol Metab Lab, London, England.;Univ Cambridge, Dept Biochem, Cambridge, England.;Univ Cambridge, Cambridge Syst Biol Ctr, Cambridge, England.;Charite Univ Med Berlin, Dept Biochem, Berlin, Germany..
    Machine Learning Predicts the Yeast Metabolome from the Quantitative Proteome of Kinase Knockouts2018In: CELL SYSTEMS, ISSN 2405-4712, Vol. 7, no 3, p. 269-+Article in journal (Refereed)
    Abstract [en]

    A challenge in solving the genotype-to-phenotype relationship is to predict a cell's metabolome, believed to correlate poorly with gene expression. Using comparative quantitative proteomics, we found that differential protein expression in 97 Saccharomyces cerevisiae kinase deletion strains is non-redundant and dominated by abundance changes in metabolic enzymes. Associating differential enzyme expression landscapes to corresponding metabolomes using network models provided reasoning for poor proteome-metabolome correlations; differential protein expression redistributes flux control between many enzymes acting in concert, a mechanismnot captured by one-to-one correlation statistics. Mapping these regulatory patterns using machine learning enabled the prediction of metabolite concentrations, as well as identification of candidate genes important for the regulation of metabolism. Overall, our study reveals that a large part of metabolism regulation is explained through coordinated enzyme expression changes. Our quantitative data indicate that this mechanism explains more than half of metabolism regulation and underlies the interdependency between enzyme levels and metabolism, which renders the metabolome a predictable phenotype.

  • 126659. Zeleznik, Michael P.
    et al.
    Maguire Jr., Gerald Q.
    Baxter, Brent S.
    University of Utah.
    PACS Data-base Design1983In: Proceedings of the Society of Photo-Optical Instrumentation Engineers, ISSN 0361-0748, Vol. 418, p. 287-295Article in journal (Refereed)
  • 126660. Zeleznik, Michael P.
    et al.
    Maguire Jr., Gerald Q.
    Baxter, Brent S.
    University of Utah.
    Noz, Marilyn E.
    New York University.
    Schimpf, James H.
    New York University.
    Horii, Steven C.
    New York University.
    PACS User Level Requirements1983In: Proceedings of the Society of Photo-Optical Instrumentation Engineers, ISSN 0361-0748, Vol. 418, p. 172-177Article in journal (Refereed)
  • 126661.
    Zeli, Velibor
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Brethouwer, Geert
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Wallin, Stefan
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Johansson, Arne V.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Consistent Boundary-Condition Treatment for Computation of the Atmospheric Boundary Layer Using the Explicit Algebraic Reynolds-Stress Model2019In: Boundary-layer Meteorology, ISSN 0006-8314, E-ISSN 1573-1472, Vol. 171, no 1, p. 53-77Article in journal (Refereed)
    Abstract [en]

    Standard turbulence models for the atmospheric boundary layer (ABL) typically use boundary conditions based on the Monin-Obukhov similarity theory (MOST). This can lead to inconsistency between the boundary condition and the closure model. Here, we propose a new boundary-condition treatment of the stratified ABL, derived for the so-called explicit algebraic Reynolds-stress model. The boundary conditions correspond to the relations for vanishing buoyancy effects that are valid close to the ground. The solution for the stratified surface layer is in agreement with the surface scaling physics and MOST functions. This was validated in a simulation of an idealized diurnal cycle of the ABL based on the second Global Energy and Water cycle Experiment (GEWEX) Atmospheric Boundary Layer Study (GABLS2) case.

  • 126662.
    Zeli, Velibor
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Zorica, Dusan
    Analytical and numerical treatment of the heat conduction equation obtained via time-fractional distributed-order heat conduction law2018In: Physica A: Statistical Mechanics and its Applications, ISSN 0378-4371, E-ISSN 1873-2119, Vol. 492, p. 2316-2335Article in journal (Refereed)
    Abstract [en]

    Generalization of the heat conduction equation is obtained by considering the system of equations consisting of the energy balance equation and fractional-order constitutive heat conduction law, assumed in the form of the distributed-order Cattaneo type. The Cauchy problem for system of energy balance equation and constitutive heat conduction law is treated analytically through Fourier and Laplace integral transform methods, as well as numerically by the method of finite differences through Adams-Bashforth and Grunwald-Letnikov schemes for approximation derivatives in temporal domain and leap frog scheme for spatial derivatives. Numerical examples, showing time evolution of temperature and heat flux spatial profiles, demonstrate applicability and good agreement of both methods in cases of multi-term and power-type distributed-order heat conduction laws.

  • 126663.
    Zeller, Silvan
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Secure Self-Reconfiguring Services to Mitigate DoS Attacks2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Protecting web services from cyber attacks is a complex problem requiring many layers of defense and mitigation strategies. Out of the diverse range of attacks, denial of service (DoS) attacks on the business logic – or the domain – are poorly studied and no widely accepted general-purpose software product to prevent these attacks exists today. At the same time, in light of the growing importance of e-commerce, defense mechanisms should be designed in a way to be self-reconfiguring, as manual reconfiguration does not scale well. In this work, a rule-based intrusion detection system (IDS) is proposed which logs the behaviour of each user and decides upon a service level based on past behaviour. The implementation is achieved by applying runtime verification (RV), a lightweight formal method which can be utilized to observe traces of user behaviour in real time. The applicability of this approach is measured by means of conducting experiments on a web service, a mock-up hotel chain which grants three different service levels for users based on their individual trust rating. Synthetic traces of bookings and cancellations are issued to account for the detection rate of the IDS and the efficacy of its mitigation strategy. The results indicate that RV is a viable approach for creating a rule-based IDS. The IDS may be tuned to attain a high detection rate of more than 95% while preserving a low false positive rates of less than 3%. Furthermore, attacks are mitigated by changing the business rules for users who have been identified as being malicious, resulting in an increased occupancy of the hotel. Lastly, RV is shown to be significantly more scalable and expressive than regular formal methods, such as model checking. Even though the results seem promising, testing the system on real traces and possibly with varying thresholds remains future work.

  • 126664. Zellers, M.
    et al.
    House, David
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Alexanderson, Simon
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Prosody and hand gesture at turn boundaries in Swedish2016In: Proceedings of the International Conference on Speech Prosody, International Speech Communications Association , 2016, p. 831-835Conference paper (Refereed)
    Abstract [en]

    In order to ensure smooth turn-taking between conversational participants, interlocutors must have ways of providing information to one another about whether they have finished speaking or intend to continue. The current work investigates Swedish speakers’ use of hand gestures in conjunction with turn change or turn hold in unrestricted, spontaneous speech. As has been reported by other researchers, we find that speakers’ gestures end before the end of speech in cases of turn change, while they may extend well beyond the end of a given speech chunk in the case of turn hold. We investigate the degree to which prosodic cues and gesture cues to turn transition in Swedish face-to-face conversation are complementary versus functioning additively. The co-occurrence of acoustic prosodic features and gesture at potential turn boundaries gives strong support for considering hand gestures as part of the prosodic system, particularly in the context of discourse-level information such as maintaining smooth turn transition.

  • 126665.
    Zellers, Margaret
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Speech Communication and Technology.
    Perception of pitch tails at potential turn boundaries in Swedish2014In: Proceedings of the Annual Conference of the International Speech Communication Association, 2014, p. 1944-1948Conference paper (Refereed)
    Abstract [en]

    In a number of languages, intonational patterns at prosodic boundaries are considered to be relevant for turn transition or turn hold. A perception experiment tested the influence of fundamental frequency (F0) peak height and rising final contours on Swedish listeners’ judgment about whether a speaker wanted to hold the turn. While F0 peak height, as has been previously shown, did influence listeners’ judgments, the end height of rising pitch tails apparently did not influence listeners’ judgments about whether a speaker planned to continue talking, even though they showed sensitivity to the differences in a discrimination task. The differences in responses in the tasks, as well as the difference from results found for other languages, may indicate that listeners used comparative prominence to guide their judgments, rather than intonation playing a direct role in the turn-transition system.

  • 126666.
    Zellers, Margaret
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Speech Communication and Technology.
    Pitch and lengthening as cues to turn transition in Swedish2013In: Proceedings of Interspeech 2013, 2013, p. 248-252Conference paper (Refereed)
    Abstract [en]

    In many cases of turn transition in conversation, a new speaker may respond to phonetic cues from the end of the prior turn, including variation in prosodic features such as pitch and final lengthening. Although consistent pitch and lengthening features are well-established for some languages at potential points of turn transition, this is not necessarily the case for Swedish. The current study uses a two-alternative forced choice task to investigate how variation in pitch contour and lengthening at the ends of syntactically complete turns can influence listeners’ expectations of turn hold or turn transition. Both lengthening and pitch contour features were found to influence listeners’ judgments about whether turn transition would occur, with shorter length and higher final pitch peaks associated with turn hold. Furthermore, listeners were more certain about their judgments when asked about turn-hold rather than turn-change, suggesting an imbalance in the strength of turn-hold versus turn-transition cues.

  • 126667.
    Zellers, Margaret
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Speech Communication and Technology. University of Stuttgart, Germany.
    Prosodic Variation and Segmental Reduction and Their Roles in Cuing Turn Transition in Swedish2017In: Language and Speech, ISSN 0023-8309, E-ISSN 1756-6053, Vol. 60, no 3, p. 454-478Article in journal (Refereed)
    Abstract [en]

    Prosody has often been identified alongside syntax as a cue to turn hold or turn transition in conversational interaction. However, evidence for which prosodic cues are most relevant, and how strong those cues are, has been somewhat scattered. The current study addresses prosodic cues to turn transition in Swedish. A perception study looking closely at turn changes and holds in cases where the syntax does not lead inevitably to a particular outcome shows that Swedish listeners are sensitive to duration variations, even in the very short space of the final unstressed syllable of a turn, and that they may use pitch cues to a lesser extent. An investigation of production data indicates that duration, and to some extent segmental reduction, demonstrate consistent variation in relation to the types of turn boundaries they accompany, while fundamental frequency and glottalization do not. Taken together, these data suggest that duration may be the primary cue to turn transition in Swedish conversation, rather than fundamental frequency, as some other studies have suggested.

  • 126668.
    Zellers, Margaret
    Department of Language and Linguistic Science, University of York, York, UK .
    Prosodic variation for topic shift and other functions in local contrasts in conversation2013In: Phonetica, ISSN 0031-8388, E-ISSN 1423-0321, Vol. 69, no 4, p. 231-253Article in journal (Refereed)
    Abstract [en]

    Speakers and listeners have been shown to use phonetic cues to help them in tracking the ongoing structure of conversational interaction, but fragmentation between qualitative and quantitative research means that the forms and functions of these cues have been given varying characterizations. The current study explores prosodic variation in contrastive structures in conversational data, using a combined methodology adopting aspects from both qualitative (conversation analysis) and quantitative (experimental phonetics/phonology) approaches. Statistical and conversation-analytical methods used together reveal relationships between prosodic variation and interactional function, such as variations in pitch range across adjacent turns being linked to the presence of 'stepwise' topic changes.

  • 126669.
    Zellers, Margaret
    et al.
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Speech Communication and Technology.
    House, David
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Speech Communication and Technology.
    Parallels between hand gestures and acoustic prosodic features in turn-taking2015In: 14th International Pragmatics Conference, Antwerp, Belgium, 2015, p. 454-455Conference paper (Refereed)
  • 126670.
    Zellers, Margaret
    et al.
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Speech Communication and Technology.
    Ogden, Richard
    Exploring Interactional Features with Prosodic Patterns2014In: Language and Speech, ISSN 0023-8309, E-ISSN 1756-6053, Vol. 57, no 3, p. 285-309Article in journal (Refereed)
    Abstract [en]

    This study adopts a multiple-methods approach to the investigation of prosody, drawing on insights from a quantitative methodology (experimental prosody research) as well as a qualitative one (conversation analysis). We use a k-means cluster analysis to investigate prosodic patterns in conversational sequences involving lexico-semantic contrastive structures. This combined methodology demonstrates that quantitative/statistical methods are a valuable tool for making relatively objective characterizations of acoustic features of speech, while qualitative methods are essential for interpreting the quantitative results. We find that in sequences that maintain global prosodic characteristics across contrastive structures, participants orient to interactional problems, such as determining who has the right to the floor, or avoiding disruption of an ongoing interaction. On the other hand, in sequences in which the global prosody is different across contrastive structures, participants do not generally appear to be orienting to such problems of alignment. Our findings expand the interpretation of "contrastive prosody" that is commonly used in experimental prosody approaches, while providing a way for conversation-analytic research to improve quantification and generalizability of findings.

  • 126671.
    Zemke, Stefan
    KTH, Superseded Departments, Computer and Systems Sciences, DSV.
    Data mining for prediction - financial series case2003Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Hard problems force innovative approaches and attention todetail, their exploration often contributing beyond the areainitially attempted. This thesis investigates the data miningprocess resulting in a predictor for numerical series.Theseries experimented with come from financial data - usuallyhard to forecast.

    One approach to prediction is to spot patterns in the past,when we already know what followed them, and to test on morerecent data. If a pattern is followed by the same outcomefrequently enough, we can gain confidence that it is a genuinerelationship.

    Because this approach does not assume any special knowledgeor form of the regularities, the method is quite general -applicable to other time series, not just financial. However,the generality puts strong demands on the patterndetection - asto notice regularities in any of the many possible forms.

    The thesis' quest for an automated pattern-spotting involvesnumerous data mining and optimization techniques: neuralnetworks, decision trees, nearest neighbors, regression,genetic algorithms and other. Comparison of their performanceon a stock exchange index data is one of the contributions.

    As no single technique performed sufficiently well, a numberof predictors have been put together, forming a votingensemble. The vote is diversified not only by differenttraining data - as usually done - but also by a learning methodand its parameters. An approach is also proposed how tospeed-up a predictor fine-tuning.

    The algorithm development goes still further: A predictioncan only be as good as the training data, therefore the needfor good data preprocessing. In particular, new multivariatediscretization and attribute selection algorithms arepresented.

    The thesis also includes overviews of prediction pitfallsand possible solutions, as well as of ensemble-building forseries data with financial characteristics, such as noise andmany attributes.

    The Ph.D. thesis consists of an extended background onfinancial prediction, 7 papers, and 2 appendices.

  • 126672.
    Zemovski, Mikael
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Interval Based Integer Ambiguity Resolution Using Multiple Antennas: Applied to airplane attitude determination2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Finding the correct integers is the key to high precision range measurements. This has been an issue of investigation since the early 1980’s and many different techniques have been developed, none of them can guarantee to resolve the correct integers in 100% of the cases(Kim & Langley, 2000) though. This thesis focuses on a new approach for Integer Ambiguity Resolution (IAR), using a geometric approach and Interval Analysis (IA). The new method can guarantee that if all measurement errors are bounded by the interval bands the correct integers will always be found. Depending on the width of the interval bands though, there may be more than one solution. The research objective of the thesis is to determine if the Interval Based Integer Am-biguity Resolution (IBIAR) method can be used for accurate attitude determination with only one remaining (correct) solution. Earlier results using the Bounded integer ambiguity resolution using interval analysis (BOUNDS) algorithm (van Kampen, 2010) have shown that one solution can not be obtained for all epochs when applied to flight data from a Cessna Citation II research airplane equipped with three antennas. The analysis did not make use of two frequencies, comparing the baseline orientations and adding an extra antenna though. These aspects are added to the BOUNDS algorithm in order to potentially reduce the number of solutions. Further the effects of the noise on both the carrier phase measurements and baseline lengths are investigated. All simulations are done off line as no real flight data is available for the test configurations. The simulations are loosely based on the Cessna Citation II research airplane belonging to the Dutch National Aerospace Laboratory (NLR) and Delft University of Technology (DUT). For all simulations the correct solution is bounded by the noise levels, which means that the BOUNDS algorithm theoretically always finds the correct solution. Further it is assumed that there are no multipath effects, no restrictions on the attitude angles the airplane can fly with, that the antennas always have a clear view of the satellites and the cut off angle is zero degrees.

    The conclusion of the thesis is that the IBIAR method can be used for attitude determination where one (correct) solution remains but the accuracy of the solution is low. The thesis gives recommendations on how to improve the accuracy of the attitude angles.

  • 126673. Zendehboudi, A.
    et al.
    Mota-Babiloni, A.
    Makhnatch, Pavel
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Saidur, R.
    Sait, S. M.
    Modeling and multi-objective optimization of an R450A vapor compression refrigeration system2019In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 100, p. 141-155Article in journal (Refereed)
    Abstract [en]

    The main objective of this work is to comprehensively investigate R450A behavior in refrigeration systems and subsequently optimize the main operating variables for the first time to reach the maximum performance. For this purpose, a hybrid multi-objective optimization model coupling response surface method and non-dominated sorted genetic algorithm II is established. The regression analysis results reveal a good agreement of experimental data samples with the quadratic polynomial models with a coefficient of determination exceeding 0.97. The optimum results for the first scenario indicate that the reduction in the motor-compressor electrical power consumption and discharge temperature is 18.39% and 53.51%, respectively, and percentage of growth in the refrigerant mass flow rate is 215.57% when the middle evaporator temperature, middle condenser temperature, superheating degree, and subcooling degree change from −14.95 °C to 8.71°C, 31.28 °C to 24.50°C, 13.12 K to 10.49 K, and 15.65 K to 15.66 K, respectively.

  • 126674. Zender, H.
    et al.
    Jensfelt, Patric
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP. KTH, School of Computer Science and Communication (CSC), Centres, Centre for Autonomous Systems, CAS.
    Kruijff, G.-J. M.
    Human- and Situation-Aware People Following2007In: 2007 RO-MAN: 16TH IEEE INTERNATIONAL SYMPOSIUM ON ROBOT AND HUMAN INTERACTIVE COMMUNICATION, VOLS 1-3, 2007, p. 1124-1129Conference paper (Refereed)
    Abstract [en]

    The paper presents an approach to intelligent, interactive people following for autonomous robots. The approach combines robust methods for simultaneous localization and mapping and for people tracking in order to yield a socially and environmentally sensitive people following behavior. Unlike current purely reactive approaches ("nearest point following") it enables the robot to follow a human in a socially acceptable way, providing verbal and non-verbal feedback to the user where necessary. At the same time, the robot makes use of information about the spatial and functional organization of its environment, so that it can anticipate likely actions performed by a human, and adjust its motion accordingly. As a result, the robot's behaviors become less reactive and more intuitive when following people around an indoor environment. The approach has been fully implemented and tested.

  • 126675. Zender, H.
    et al.
    Jensfelt, Patric
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP. KTH, School of Computer Science and Communication (CSC), Centres, Centre for Autonomous Systems, CAS.
    Mozos, O. M.
    Kruijff, G.-J. M.
    Burgard, W.
    An integrated robotic system for spatial understanding and situated interaction in indoor environments2007In: AAAI-07/IAAI-07 Proceedings: 22nd AAAI Conference on Artificial Intelligence and the 19th Innovative Applications of Artificial Intelligence Conference, 2007, p. 1584-1589Conference paper (Refereed)
    Abstract [en]

    A major challenge in robotics and artificial intelligence lies in creating robots that are to cooperate with people in human-populated environments, e.g. for domestic assistance or elderly care. Such robots need skills that allow them to interact with the world and the humans living and working therein. In this paper we investigate the question of spatial understanding of human-made environments. The functionalities of our system comprise perception of the world, natural language, learning, and reasoning. For this purpose we integrate state-of-the-art components from different disciplines in AI, robotics and cognitive systems into a mobile robot system. The work focuses on the description of the principles we used for the integration, including cross-modal integration, ontology-based mediation, and multiple levels of abstraction of perception. Finally, we present experiments with the integrated “CoSy Explorer ” 1 system and list some of the major lessons that were learned from its design, implementation, and evaluation.

  • 126676. Zender, H.
    et al.
    Mozos, O. Martinez
    Jensfelt, Patric
    KTH, School of Computer Science and Communication (CSC), Centres, Centre for Autonomous Systems, CAS. KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Kruijff, G. J. M.
    Burgard, W.
    Conceptual spatial representations for indoor mobile robots2008In: Robotics and Autonomous Systems, ISSN 0921-8890, E-ISSN 1872-793X, Vol. 56, no 6, p. 493-502Article in journal (Refereed)
    Abstract [en]

    We present an approach for creating conceptual representations of human-made indoor environments using mobile robots. The concepts refer to spatial and functional properties of typical indoor environments. Following different findings in spatial cognition, our model is composed of layers representing maps at different levels of abstraction. The complete system is integrated in a mobile robot endowed with laser and vision sensors for place and object recognition. The system also incorporates a linguistic framework that actively supports the map acquisition process, and which is used for situated dialogue. Finally, we discuss the capabilities of the integrated system.

  • 126677. Zender, J. J.
    et al.
    Kariyappa, R.
    Giono, Gabriel
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Bergmann, M.
    Delouille, V.
    Dame, L.
    Hochedez, J. -F
    Kumara, S. T.
    Segmentation of photospheric magnetic elements corresponding to coronal features to understand the EUV and UV irradiance variability2017In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 605, article id A41Article in journal (Refereed)
    Abstract [en]

    Context. The magnetic field plays a dominant role in the solar irradiance variability. Determining the contribution of various magnetic features to this variability is important in the context of heliospheric studies and Sun-Earth connection. Aims. We studied the solar irradiance variability and its association with the underlying magnetic field for a period of five years (January 2011-January 2016). We used observations from the Large Yield Radiometer (LYRA), the Sun Watcher with Active Pixel System detector and Image Processing (SWAP) on board PROBA2, the Atmospheric Imaging Assembly (AIA), and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). Methods. The Spatial Possibilistic Clustering Algorithm (SPoCA) is applied to the extreme ultraviolet (EUV) observations obtained from the AIA to segregate coronal features by creating segmentation maps of active regions (ARs), coronal holes (CHs) and the quiet sun (QS). Further, these maps are applied to the full-disk SWAP intensity images and the full-disk (FD) HMI line-of-sight (LOS) magnetograms to isolate the SWAP coronal features and photospheric magnetic counterparts, respectively. We then computed fulldisk and feature-wise averages of EUV intensity and line of sight (LOS) magnetic flux density over ARs/CHs/QS/FD. The variability in these quantities is compared with that of LYRA irradiance values. Results. Variations in the quantities resulting from the segmentation, namely the integrated intensity and the total magnetic flux density of ARs/CHs/QS/FD regions, are compared with the LYRA irradiance variations. We find that the EUV intensity over ARs/CHs/QS/FD is well correlated with the underlying magnetic field. In addition, variations in the full-disk integrated intensity and magnetic flux density values are correlated with the LYRA irradiance variations. Conclusions. Using the segmented coronal features observed in the EUV wavelengths as proxies to isolate the underlying magnetic structures is demonstrated in this study. Sophisticated feature identification and segmentation tools are important in providing more insights into the role of various magnetic features in both the short-and long-term changes in the solar irradiance.

  • 126678. Zeng, H
    et al.
    Isacsson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Evaluation of Low Temperature Properties of Asphalt Mixtures1998Conference paper (Refereed)
  • 126679. Zeng, H
    et al.
    Isacsson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Low Temperature Cracking of Bituminous Courses - State of the Art1995Report (Other academic)
  • 126680. Zeng, H
    et al.
    Isacsson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Low Temperature Cracking of Bituminous Courses - State of the Art1995Report (Other academic)
  • 126681. Zeng, Hong Li
    et al.
    Hertz, John
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Roudi, Yasser
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    L-1 regularization for reconstruction of a non-equilibrium Ising model2014In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 89, no 10, p. 105002-Article in journal (Refereed)
    Abstract [en]

    The couplings in a sparse asymmetric, asynchronous Ising network are reconstructed using an exact learning algorithm. L-1 regularization is used to remove the spurious weak connections that would otherwise be found by simply maximizing the log likelihood of a finite data set. In order to see how L-1 regularization works in detail, we perform the calculation in several ways including (1) by iterative minimization of a cost function equal to minus the log likelihood of the data plus an L-1 penalty term, and (2) an approximate scheme based on a quadratic expansion of the cost function around its minimum. In these schemes, we track how connections are pruned as the strength of the L-1 penalty is increased from zero to large values. The performance of the methods for various coupling strengths is quantified using receiver operating characteristic curves, showing that increasing the coupling strength improves reconstruction quality.

  • 126682. Zeng, Hong-Li
    et al.
    Alava, Mikko
    Aurell, Erik
    KTH, School of Computer Science and Communication (CSC), Computational Biology, CB. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Hertz, John
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Roudi, Yasser
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Maximum Likelihood Reconstruction for Ising Models with Asynchronous Updates2013In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 110, no 21, p. 210601-Article in journal (Refereed)
    Abstract [en]

    We describe how the couplings in an asynchronous kinetic Ising model can be inferred. We consider two cases: one in which we know both the spin history and the update times and one in which we know only the spin history. For the first case, we show that one can average over all possible choices of update times to obtain a learning rule that depends only on spin correlations and can also be derived from the equations of motion for the correlations. For the second case, the same rule can be derived within a further decoupling approximation. We study all methods numerically for fully asymmetric Sherrington-Kirkpatrick models, varying the data length, system size, temperature, and external field. Good convergence is observed in accordance with the theoretical expectations.

  • 126683. Zeng, Hong-Li
    et al.
    Aurell, Erik
    KTH, School of Computer Science and Communication (CSC), Computational Biology, CB.
    Alava, Mikko
    Mahmoudi, Hamed
    Network inference using asynchronously updated kinetic Ising model2011In: Physical Review E, ISSN 1539-3755, Vol. 83, no 4, p. 041135-Article in journal (Refereed)
    Abstract [en]

    Network structures are reconstructed from dynamical data by respectively naive mean field (nMF) and Thouless-Anderson-Palmer (TAP) approximations. TAP approximation adds simple corrections to the nMF approximation, taking into account the effect of the focused spin on itself via its influence on other neighboring spins. For TAP approximation, we use two methods to reconstruct the network: (a) iterative method; (b) casting the inference formula to a set of cubic equations and solving it directly. We investigate inference of the asymmetric Sherrington-Kirkpatrick (aS-K) model using asynchronous update. The solutions of the set of cubic equations depend on temperature T in the aS-K model, and a critical temperature T-c approximate to 2.1 is found. The two methods for TAP approximation produce the same results when the iterative method is convergent. Compared to nMF, TAP is somewhat better at low temperatures, but approaches the same performance as temperature increases. Both nMF and TAP approximation reconstruct better for longer data length L, but for the degree of improvement, TAP performs better than nMF.

  • 126684.
    Zeng, Jingna
    et al.
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS. Universidade de Lisboa, Portugal.
    Barreto, J.
    Haridi, Seif
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Rodrigues, L.
    Romano, P.
    The Future(s) of Transactional Memory2016In: Proceedings of the International Conference on Parallel Processing, Institute of Electrical and Electronics Engineers (IEEE), 2016, p. 442-451Conference paper (Refereed)
    Abstract [en]

    This work investigates how to combine two powerful abstractions to manage concurrent programming: Transactional Memory (TM) and futures. The former hides from programmers the complexity of synchronizing concurrent access to shared data, via the familiar abstraction of atomic transactions. The latter serves to schedule and synchronize the parallel execution of computations whose results are not immediately required. While TM and futures are two widely investigated topics, the problem of how to exploit these two abstractions in synergy is still largely unexplored in the literature. This paper fills this gap by introducing Java Transactional Futures (JTF), a Java-based TM implementation that allows programmers to use futures to coordinate the execution of parallel tasks, while leveraging transactions to synchronize accesses to shared data. JTF provides a simple and intuitive semantic regarding the admissible serialization orders of the futures spawned by transactions, by ensuring that the results produced by a future are always consistent with those that one would obtain by executing the future sequentially. Our experimental results show that the use of futures in a TM allows not only to unlock parallelism within transactions, but also to reduce the cost of conflicts among top-level transactions in high contention workloads.

  • 126685.
    Zeng, Jingna
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Software and Computer systems, SCS. INESC-ID/Instituto Superior Tecnico, Universidade de Lisboa, Portugal.
    Romano, P.
    Barreto, J.
    Rodrigues, L.
    Haridi, S.
    Online tuning of parallelism degree in parallel nesting transactional memory2018In: Proceedings - 2018 IEEE 32nd International Parallel and Distributed Processing Symposium, IPDPS 2018, Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 474-483, article id 8425201Conference paper (Refereed)
    Abstract [en]

    This paper addresses the problem of self-Tuning the parallelism degree in Transactional Memory (TM) systems that support parallel nesting (PN-TM). This problem has been long investigated for TMs not supporting nesting, but, to the best of our knowledge, has never been studied in the context of PN-TMs. Indeed, the problem complexity is inherently exacerbated in PN-TMs, since these require to identify the optimal parallelism degree not only for top-level transactions but also for nested sub-Transactions. The increase of the problem dimensionality raises new challenges (e.g., increase of the search space, and proneness to suffer from local maxima), which are unsatisfactorily addressed by self-Tuning solutions conceived for flat nesting TMs. We tackle these challenges by proposing AUTOPN, an on-line self-Tuning system that combines model-driven learning techniques with localized search heuristics in order to pursue a twofold goal: i) enhance convergence speed by identifying the most promising region of the search space via model-driven techniques, while ii) increasing robustness against modeling errors, via a final local search phase aimed at refining the model's prediction. We further address the problem of tuning the duration of the monitoring windows used to collect feedback on the system's performance, by introducing novel, domain-specific, mechanisms aimed to strike an optimal trade-off between latency and accuracy of the self-Tuning process. We integrated AUTOPN with a state of the art PN-TM (JVSTM) and evaluated it via an extensive experimental study. The results of this study highlight that AUTOPN can achieve gains of up to 45× in terms of increased accuracy and 4× faster convergence speed, when compared with several on-line optimization techniques (gradient descent, simulated annealing and genetic algorithm), some of which were already successfully used in the context of flat nesting TMs.

  • 126686.
    Zeng, Ming
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Du, Rong
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Fodor, Viktória
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Computation Rate Maximization for Wireless Powered Mobile Edge Computing with NOMA2019In: Proceedings 20th IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (IEEE WoWMoM 2019), IEEE , 2019Conference paper (Refereed)
    Abstract [en]

    In this paper, we consider a mobile edge computing (MEC) network, that is wirelessly powered. Each user harvests wireless energy and follows a binary computation offloading policy, i.e., it either executes the task locally or offloads it to the MEC as a whole. For the offloading users, non-orthogonal multiple access (NOMA) is adopted for information transmission. We consider rate-adaptive computational tasks and aim at maximizing the sum computation rate of all users by jointly optimizing the individual computing mode selection (local computing or offloading), the time allocations for energy transfer and for information transmission, together with the local computing speed or the transmission power level. The major difficulty of the rate maximization problem lies in the combinatorial nature of the multiuser computing mode selection and its involved coupling with the time allocation. We also study the case where the offloading users adopt time division multiple access (TDMA) as a benchmark, and derive the optimal time sharing among the users. We show that the maximum achievable rate is the same for the TDMA and the NOMA system, and in the case of NOMA it is independent from the decoding order, which can be exploited to improve system fairness. To maximize the sum computation rate, for the mode selection we propose a greedy solution based on the wireless channel gains, combined with the optimal allocation of energy transfer time. Numerical results show that the proposed solution maximizes the computation rate in homogeneous networks, and binary offloading leads to significant gains. Moreover, NOMA increases the fairness of rate distribution among the users significantly, when compared with TDMA.

  • 126687.
    Zeng, Ming
    et al.
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Fodor, Viktoria
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Distributing Dynamic Divisible Loads2017In: 2017 IFIP Networking Conference (IFIP Networking) and Workshops, Institute of Electrical and Electronics Engineers (IEEE), 2017Conference paper (Refereed)
    Abstract [en]

    With the emergence of computing infrastructures in the cloud or at the network edge we need to address the question of how to utilize these shared resources when computational tasks are generated dynamically. While small computing tasks may be satisfied with the computing capacity of a single resource, large tasks may want to utilize multiple computing nodes and perform parallel processing to shorten the task completion time. In this paper we evaluate how additional overhead in such divisible load systems affect the efficiency of parallel processing - from the point of view of the task itself, and for the entire resource sharing system. We show that the preference of a single task may be in conflict with the allocation needed for a social optimum, which in turn depends heavily on the load as well as on the system size.

  • 126688.
    Zeng, Ming
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Fodor, Viktória
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering. KTH Royal Inst Technol, Sch Elect Engn & Comp Sci, S-10044 Stockholm, Sweden..
    Dynamic Spectrum Sharing for Load Balancing in Multi-Cell Mobile Edge Computing2020In: IEEE Wireless Communications Letters, ISSN 2162-2337, E-ISSN 2162-2345, Vol. 9, no 2, p. 189-193Article in journal (Refereed)
    Abstract [en]

    Large-scale mobile edge computing (MEC) systems require scalable solutions to allocate communication and computing resources to the users. In this letter we address this challenge by applying dynamic spectrum sharing among the base stations (BSs), together with local resource allocation in the cells. We show that the network-wide resource allocation can be transformed into a convex optimization problem, and propose a distributed, hierarchical solution with limited information exchange among the BSs. Numerical results demonstrate that the proposed solution is superior to other baseline algorithms, when wireless and computing resource allocation is not jointly optimized, or the wireless resources allocated to the BSs are fixed.

  • 126689.
    Zeng, Ming
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Fodor, Viktória
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Energy minimization for delay constrained mobile edge computing with orthogonal and non-orthogonal multiple access2020In: Ad hoc networks, ISSN 1570-8705, E-ISSN 1570-8713, Vol. 98, article id 102060Article in journal (Refereed)
    Abstract [en]

    Mobile edge computing (MEC) is envisioned as a promising technology for enhancing the computation capacities and prolonging the lifespan of mobile devices, by enabling mobile devices to offload computation-intensive tasks to servers in close proximity. For wireless communication, MEC introduces a new scenario, where computations are performed directly at the receiving side of the wireless links. Our objective is therefore to evaluate the importance of joint radio-and-computational resource allocation and spectral efficiency enhancing techniques in this new scenario. We formulate the resource allocation problem to minimize the energy consumption of computation offloading of delay sensitive tasks and propose near-optimal solutions for both orthogonal and non-orthogonal multiple access schemes, with the optimal joint allocation of computing resources and transmission power. Our numerical results demonstrate the superiority of non-orthogonal multiple access over its orthogonal counterpart and the importance of joint resource allocation, especially in scenarios with strict delay limits, where both the transmission and the computational resources are scarce.

  • 126690.
    Zeng, Ming
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Fodor, Viktória
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Energy-efficient Resource Allocation for NOMA-assisted Mobile Edge Computing2018In: 2018 IEEE 29TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS (PIMRC), IEEE , 2018, p. 1794-1799Conference paper (Refereed)
    Abstract [en]

    In this paper we evaluate the effect of increased wireless spectral efficiency on the performance of mobile edge computing. Specifically, we study the energy minimization of computation offloading for a multi carrier non-orthogonal multiple access (NOMA) assisted mobile edge computing (MEC) system. A joint radio-and-computational resource allocation problem is formulated, in which three different resources should be appropriately allocated, including subcarriers, transmission power and computational resources. The formulated resource allocation problem belongs to mixed integer nonlinear programming (MILNP) and is NP-hard. We propose therefore a heuristic solution consisting of two steps, NOMA clustering and subcarrier allocation, and joint computational resource and power allocation. Our numerical results show that NOMA based MEC significantly outperforms its OMA counterpart, especially in scenarios with strict delay limits, where both the transmission and the computational resources become scarce.

  • 126691.
    Zeng, Ming
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems Engineering.
    Fodor, Viktória
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems Engineering.
    On the Performance of Parallel Processing in Dynamic Resource Sharing Systems2019In: Proceedings - 20th International Conference on High Performance Computing and Communications, 16th International Conference on Smart City and 4th International Conference on Data Science and Systems, HPCC/SmartCity/DSS 2018, Institute of Electrical and Electronics Engineers Inc. , 2019, p. 30-36Conference paper (Refereed)
    Abstract [en]

    Parallel processing has the potential of significantly decreasing the service time for a single computational task. Meanwhile, as each task occupies more resources, the number of simultaneously supported tasks declines. This tradeoff is interesting when resources are accessed by many users in a dynamic way, like in the case of cloud or fog computing. In this paper, we evaluate how the level of parallelization and the eventual overheads affect the response time in these dynamic resource sharing systems. We show the counterintuitive finding that even when parallelization has no overhead, the allocation of all resources to a task is suboptimal if the service times have large coefficient of variation. Moreover, we evaluate the scalability properties, and provide guidelines for the optimal level of parallelization under different types of overhead.

  • 126692.
    Zeng, Ming
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Fodor, Viktória
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Sum-Rate Maximization under QoS Constraint in MIMO-NOMA Systems2018In: 2018 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE (WCNC), IEEE , 2018Conference paper (Refereed)
    Abstract [en]

    This paper addresses the power allocation challenge for the downlink transmission in non-orthogonal multiple access (NOMA) systems applying multiple input multiple output transceivers. We consider the case when users are paired to form NOMA clusters, and share a common power budget. We provide low complexity power allocation methods within the clusters and across the clusters, that, together, maximize the sum-rate of the network, while guaranteeing a minimum quality of service for the users with weak channel condition. We show that compared to equal power allocation for the clusters, the proposed power allocation scheme improves the system fairness significantly, without decreasing the aggregate performance.

  • 126693. Zeng, Q.
    et al.
    Gao, Liang
    Beijing University.
    Liu, R.
    Interferometric Phase Noise Filtering Based on Adaptive Optimized Wavelet Packets Transform2006In: Dragon Programme Mid-Term Results, Proceedings / [ed] Lacoste, H, 2006, p. 363-367Conference paper (Other academic)
    Abstract [en]

    Interferometric synthetic aperture radar (InSAR) has been used widely in investigation of surface deformation, such as earthquake, volcano, ground subsistence and landslides. But there are still some obstacles standing in the stage of the application. One of those is the phase noise in the interferogra. In particular, there are much noise in the inteferograms derived in steep topographic area with dense vegetation cover, such as the Three Gorges Area in China. This paper addresses the problem of phase noise filtering in InSAR. One difficulty of phase noise filtering of SAR interferometry is to reduce phase noise as much as possible while maintaining the phase information at the same time. The use of wavelet transform filtering is easy to ignore the high-frequency information, and make the image detail slur. One of the merits of wavelet packets transform is that most detail information in each frequency band will be analyzed. But over subtle decomposition in the high frequency bands, where noise is dominant, is apt to treat phase noise in those bands as signal. This would lead to erroneous result. In this paper, a phase noise filtering method based on adaptive optimized wavelet packets transform, or optimized tree-structured wavelet transform, is given out. By checking the correlation of wavelet coefficients in each wavelet scale, we decide whether each wavelet component in this scale should be decomposed further or not. According to such an adaptively constructed wavelet packets tree, complex phase image is decomposed. For the purpose of keeping the phase information, wavelet transform is executed in complex domain, and different threshold values are computed at each wavelet scale by using the intensity of their wavelet coefficients. Moreover, we have used an improved thresholding process method to try to overcome the disadvantages by both hard-thresholding and soft-thresholding methods.

  • 126694. Zeng, Qiao-Shi
    et al.
    Ding, Yang
    Mao, Wendy L.
    Luo, Wei
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Blomqvist, Andreas
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Yang, Wenge
    Shu, Jinfu
    Sinogeikin, Stas V.
    Meng, Yue
    Brewe, Dale L.
    Jiang, Jian-Zhong
    Mao, Ho-Kwang
    Substitutional alloy of Ce and Al2009In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 106, no 8, p. 2515-2518Article in journal (Refereed)
    Abstract [en]

    The formation of substitutional alloys has been restricted to elements with similar atomic radii and electronegativity. Using high-pressure at 298 K, we synthesized a face-centered cubic disordered alloy of highly dissimilar elements (large Ce and small Al atoms) by compressing the Ce3Al intermetallic compound > 15 GPa or the Ce3Al metallic glass > 25 GPa. Synchrotron X-ray diffraction, Ce L-3-edge absorption spectroscopy, and ab initio calculations revealed that the pressure-induced Kondo volume collapse and 4f electron delocalization of Ce reduced the differences between Ce and Al and brought them within the Hume-Rothery (HR) limit for substitutional alloying. The alloy remained after complete release of pressure, which was also accompanied by the transformation of Ce back to its ambient 4f electron localized state and reversal of the Kondo volume collapse, resulting in a non-HR alloy at ambient conditions.

  • 126695.
    Zeng, Shuo Wei
    KTH, Superseded Departments, Electronic Systems Design.
    Modern manufacturing automation: the integration of control, maintenance and technical management1998Licentiate thesis, comprehensive summary (Other scientific)
  • 126696. Zeng, Tui
    et al.
    Zhou, Yan
    Åkerman, Johan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Lai, P. T.
    Pong, Philip W. T.
    Linear Phase Tuning of Spin Torque Oscillators Using In-Plane Microwave Fields2014In: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 50, no 1, p. 1400104-Article in journal (Refereed)
    Abstract [en]

    We demonstrate numerically and analytically that a nano-pillar spin torque oscillator (STO), operating either with in-plane or out-ofplane free-layer precession, locks to a microwave field (H-ac) having the same frequency as the STO. By varying the spatial direction of the microwave field, we further show the preferred phase shift (Delta Phi(0)) between the STO and H-ac can be tuned in a linear fashion. We explain this phenomenon by using a magnetic-energy-based analysis. Our results provide a way to synchronize serially connected STOs by tuning the phase shift of each individual STO with external microwave field, which may enhance the locking efficiency, the locking range, and the output power of the serially connected STOs.

  • 126697. Zeng, Xianghui
    et al.
    Zhang, Yuning
    Wu, Zhihua
    Lundberg, Pontus
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Nystrom, Andreas M.
    Hyperbranched Copolymer Micelles as Delivery Vehicles of Doxorubicin in Breast Cancer Cells2012In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 50, no 2, p. 280-288Article in journal (Refereed)
    Abstract [en]

    Four types of drug nanoparticles (NPs) based on amphiphilic hyperbranched block copolymers were developed for the delivery of the chemotherapeutic doxorubicin (DOX) to breast cancer cells. These carriers have their hydrophobic interior layer composed of the hyperbranched aliphatic polyester, Boltorn (R) H30 or Boltorn (R) H40, that are polymers of poly 2,2-bis (methylol) propionic acid (bis-MPA), while the outer hydrophilic shell was composed of about 5 poly(ethylene glycol) (PEG) segments of 5 or 10 kDa molecular weight. A chemotherapeutic drug DOX, was further encapsulated in the interior of these polymer micelles and was shown to exhibit a controlled release profile. Dynamic light scattering and transmission electron microscopy analysis confirmed that the NPs were uniformly sized with a mean hydrodynamic diameter around 110 nm. DOX-loaded H30-PEG10k NPs exhibited controlled release over longer periods of time and greater cytotoxicity compared with the other materials developed against our tested breast cancer cell lines. Additionally, flow cytometry and confocal scanning laser microscopy studies indicated that the cancer cells could internalize the DOX-loaded H30-PEG10k NPs, which contributed to the sustained drug release, and induced more apoptosis than free DOX did. These findings indicate that the H30-PEG10k NPs may offer a very promising approach for delivering drugs to cancer cells. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 280-288, 2012

  • 126698. Zeng, Y
    et al.
    Chen, XS
    Lu, W
    Fu, Ying
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Exciton polaritons of nano-spherical-particle photonic crystals in compound lattices2006In: European Physical Journal B: Condensed Matter Physics, ISSN 1434-6028, E-ISSN 1434-6036, Vol. 49, no 3, p. 313-318Article in journal (Refereed)
    Abstract [en]

    Nonlocal investigations are presented for exciton-photon coupling in three-dimensional nano-spherical-particle photonic crystals in compound lattices for a tailored dielectric environment to optimize the optical properties of nano particles. The photonic band structure can be modified by tuning the nano particle size and the distance between two interlacing identical face-centered sub-lattices making up the photonic crystal lattice. A complete photonic band gap with a gap-midgap ratio as large as 40.82% has been found in the wurzite structure under the current investigation.

  • 126699. Zeng, Y.
    et al.
    Yao, S.
    Wang, Lihui
    National Research Council of Canada.
    Architecture of Web-based Distributed Systems for Gathering and Managing Product Requirements2006In: Proceedings of the 16th CIRP International Design Seminar, 2006, p. 712-717Conference paper (Refereed)
  • 126700.
    Zeng, Yinping
    et al.
    Cent S Univ, State Key Lab Powder Met, Changsha 410083, Hunan, Peoples R China..
    Du, Yong
    Cent S Univ, State Key Lab Powder Met, Changsha 410083, Hunan, Peoples R China.;Qilu Univ Technol, Adv Mat Inst, Shandong Prov Key Lab High Strength Lightweight M, Shandong Acad Sci, Jinan 250014, Shandong, Peoples R China..
    Li, Han
    Cent S Univ, State Key Lab Powder Met, Changsha 410083, Hunan, Peoples R China..
    Zhou, Peng
    Hunan Univ Sci & Technol, Xiangtan 411201, Peoples R China..
    Liu, Shuhong
    Cent S Univ, State Key Lab Powder Met, Changsha 410083, Hunan, Peoples R China..
    Cheng, Kaiming
    Qilu Univ Technol, Adv Mat Inst, Shandong Prov Key Lab High Strength Lightweight M, Shandong Acad Sci, Jinan 250014, Shandong, Peoples R China..
    Sundman, Bo
    KTH.
    Schmid-Fetzer, Rainer
    Tech Univ Clausthal, Thermochem & Mikrokinet Inst Met, Robert Koch Str 42, D-38678 Clausthal Zellerfeld, Germany..
    Dreval, Liya
    Mat Sci Int Serv GmbH, MSI, 70565 Wallgraben 100, Stuttgart, Germany..
    Thermodynamic description and solidified microstructure of the Co-Ge system2019In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 793, p. 480-491Article in journal (Refereed)
    Abstract [en]

    The Co-Ge binary system was reassessed by CALPHAD method in view of new phase diagram data and drawbacks of the previous modeling. A three-sublattice model (Co,Va)(1)(Co)(1)(Ge)(1 )was used to describe the B8(2)-type beta Co5Ge3-phase based on its crystal structure. In order to describe the transformation between ordered L1(2)-type phase (Co3Ge) and the disordered fcc_Al phase (alpha Co), one single Gibbs energy function was used for both ordered and disordered phases. In almost all the previous thermodynamic calculations, the ordered phase with a negligible homogeneity range, such as Co3Ge, is treated as a stoichiometric compound. Such a treatment is not physically sound. For (alpha Co) and (alpha Co), the magnetic contribution to Gibbs energy is taken into account. Both substitutional solution model and associated model were applied to describe the liquid phase, and thus two sets of self-consistent thermodynamic parameters for this system were obtained. It was found that the associated model can account for the experimental data more satisfactorily than the substitutional solution model, especially for the partial enthalpy of mixing data for the liquid phase. Five representative as-cast Co-Ge alloys were prepared to compare the solidified microstructure with that predicted according to thermodynamic calculations. According to the calculated Scheil solidification curves of two key alloys, the solidified microstructure for the alloys was analyzed. Also, the calculated amounts of the solidified phases in five as-cast alloys are compared with the experimental data resulting from automatic image analysis of the BSE images, showing a good agreement between the calculation and experiment, in particular for the case in which the associated model is used to describe the properties of the liquid phase. It is demonstrated that the combined use of the thermodynamic calculation and decisive experiment is an efficient strategy to obtain the desired microstructure.

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