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1
Ma la qing yi Q & A
e-Kitap

e-Kitap
Kaynak :
Internet Archive Books
Dergi:
Shanghai : Bai jia chu ban she
Yayıncı:
Shanghai : Bai jia chu ban she
Yazar(lar) :
Di Wu
Yıl :
2003
Di Wu
Yayıncı Web Sitesi
Kaydet Alıntıla
290 p. : 19 cm Ben shu li qiu yong sheng dong, Tong su de yu yan dui xian dai ai qing jin xing chan shu, Fan wei guang fan, Ru:dang jin shi dai de wang lian xian xiang, Mian bao he mei gui na ge geng zhong yao, Guan yu hun wai lian deng Bing lie ti ming:Ask Wudi Wu di(nü), Mei guo MBA, Liang xing guan xi zhuan lan zuo jia, [xiao fei zhe meimei] za zhi zhu bian jian yun ying zong jian, Zhu you[tian tian jue wu]
Sayfa sayısı :308
2
The rogue transcriptome electronic resource : using sequencing to track RNA regulation and identify unusual RNAs
Tez

Tez
Open Access
Kaynak :
Stanford University Thesis
Dergi:
Stanford University
Yayıncı:
Stanford University
Yazar(lar) :
Di Wu
Yıl :
2013
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
First, we take a look at the function of a specific type of RNA editing mediated by ADAR (adenosine deaminase that acts on RNAs). We test our hypotheses on ADAR activity and target specificity through transcriptome analysis in the context of exogenous RNAi response pathway in C. elegans. By examining of small RNA and mRNA populations in adar mutants and additional RNAi defective mutants, we show that the activity and specificity of the ADAR enzyme likely precludes the detection of its targets through conventional methods of sequence capture and analysis. Based on this understanding, we develop novel computational approaches for analysis of small RNA and mRNA populations and identify a broader set of ADAR targets, leading to a deeper understanding of the ADAR pathway, the conserved functionalities of the ADAR enzyme, and its relationship with the exogenous RNAi pathway in C. elegans. Second, we examine the dynamics of the transcriptome upon and after exposure to extreme heat. We hypothesize that the recovery response after removal from heat exposure might involve alternations in transcription regulation that are more complex than a reversal of the heat-shock induced effects, and that one such form of long-term regulation might involve the endogenous RNAi pathway and regulation via synthesis of endogenous siRNAs. By examining the dynamics of the C. elegans transcriptome during time-course of heat exposure and recovery, we reach a deeper understanding of heat shock biology and explore the relationship between endogenous siRNAs and their sequence complementary mRNA targets in the context of environmentally induced perturbance.
Sınıflandırma :
Biyotıp %98
3
Nature-inspired superlyophobic surfaces
Tez

Tez
Open Access
Kaynak :
The Dart-Europe
Dergi:
Technische Universiteit Eindhoven
Yazar(lar) :
Di Wu
Yıl :
2007
Di Wu
Yayıncı Web Sitesi
Kaydet Alıntıla
Sınıflandırma :
4
Signal eigen-analysis and L1 inversion of seismic data
Tez

Tez
Open Access
Kaynak :
The Dart-Europe
Dergi:
Imperial College London
Yazar(lar) :
Di Wu
Yıl :
2013
Di Wu
Yayıncı Web Sitesi
Kaydet Alıntıla
Sınıflandırma :
5
Does Social Media Get Your Attention?
Dergi Makalesi

Dergi Makalesi
Kaynak :
Taylor and Francis
Dergi:
Journal of Behavioral Finance
Yayıncı:
Informa UK Limited
Yazar(lar) :
Di Wu
Yıl :
2019
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
The author investigates how social media affects stock prices and post–earnings announcement drift in response to companies’ quarterly earnings announcements. Using quarterly earnings data as well Twitter and StockTwits data, the author utilizes Twitter volume and a residual methodology to generate an attention proxy that is orthogonal to the growth of Twitter accounts. The author finds that the new attention brought by social media after the earnings announcements positively affects the cumulative abnormal returns. Further, even companies reporting bad news can still have positive immediate cumulative abnormal returns if they attract enough attention from investors after an earnings announcement. The new attention effects are different in both magnitudes and statistical significance between social media popular and unpopular industries.
DOI : 10.1080/15427560.2018.1505729
Anahtar Kelimeler : Social media, Investor attention, Earnings announcement
ISSN: 1542-7560
Sayı: 2
Cilt: 20
Sayfa: 213-226
6
Theoretical studies of electronic tunneling properties in monolayer and bilayer graphene lattices
Tez

Tez
Open Access
Kaynak :
Dissertation.com
Dergi:
University of Hong Kong
Yayıncı:
University of Hong Kong
Yazar(lar) :
Di Wu
Konu :
Graphite. , Tunneling (Physics)
Yıl :
2008
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
published_or_final_version Physics master's Master of Philosophy
Tez türü: M. Phil.
Sınıflandırma :
7
Distance-based protein structure modeling
Tez

Tez
Open Access
Kaynak :
Dissertation.com
Dergi:
Iowa State University
Yayıncı:
Iowa State University
Yazar(lar) :
Di Wu
Yıl :
2006
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
Protein structure modeling can be studied based on the knowledge of interactions or distances between pairs of atoms, which is so-called distance-based protein structure modeling and this field includes problems of structure determination and refinement as well as analysis of protein dynamics. The distances for certain pairs of atoms in a protein can often be obtained based on our knowledge on various types of bond-lengths and bond-angles or from physical experiments such as nuclear magnetic resonance (NMR). The coordinates of the atoms and hence the protein structure can then be determined by using the known distances. However, it requires the solution of a mathematical problem called the distance geometry problem, which has been proven to be computationally intractable in general. On the other hand, due to insufficient distance data such as nuclear overhauser effect (NOE) data in NMR, the protein structures determined by conventional techniques usually are not as accurate as desired. Therefore, the uses of such protein structures in important applications including homology modeling and rational drug design have been severely limited. In this work, we have developed several efficient algorithms including theories for the solution of the distance geometry problem using a geometric build-up algorithm. We also introduced a knowledge-based method for protein structure refinement, in which we constructed a dedicated structural database for protein inter-atomic distance distributions and derived so-called mean force potentials to refine NMR-determined protein structures. We have participated in CASPR competition regarding comparative models and reported some substantial improvement using mean force potentials. Finally, an efficient and simple method called Local-DME calculations has been developed to study protein dynamics of NMR ensembles specifically.
Sınıflandırma :
8
Depletion and harvesting thermal energy from actuator arm electronics in hard disk drives
Tez

Tez
Open Access
Kaynak :
Dissertation.com
Dergi:
Massey University
Yayıncı:
Massey University
Yazar(lar) :
Di Wu
Konu :
Thermoelectricity , Piezoelectricity , Heat transmission , Hard disks , Mechatronics
Yıl :
2011
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
In recent years, thermally assistive magnetic recording (TAMR) has been applied on actuator arm electronics (AE) in hard disk drive (HDD). When HDD operates, temperature of the AE chip inside enclosure can be as high as 80-100 ºC, primary caused by processing and conditioning of magnetic signals and heated by wasted mechanical energy in form of thermal energy. To guarantee reliability of electronic device, AE chip junction temperature should be maintained at a relatively low level, which requires novel depletion of thermal energy. There are generally two methods to manage the thermal dissipation of chips. One is to follow existing approaches that conduct the thermal energy from the topside of the chip to a heat sink through a conductive paste, or other mediums. The other way is to dissipate the heat from the inner surface of the chip to a heat sink through silicon substrate. In this thesis, thermal analysis of AE chip junction temperature is presented and discussed. Depletion of thermal energy generated by the AE chip will be characterized among several thermal management configurations. Then, a thermal resistance network model is established for AE chip junction temperature to ambient. The thermal resistance network is based on heat transfer paths from the chip to ambient. Every thermal resistance in the network can be calculated by analytical expression. The accuracy of the presented model will be also proven through comparing the results of mathematic model and simulation. Finally, based on the thermal analysis and managements, design of a novel active thermal energy harvester to transform the wasted energy into electrical energy will be presented. Finite element analysis (FEA) software is used to simulate piezoelectric characteristics of the thermal energy harvester.
Tez türü: M. Eng.
Sınıflandırma :
9
Pedestrian detection and counting in surveillance videos
Tez

Tez
Open Access
Kaynak :
Dissertation.com
Dergi:
University of Missouri – Columbia
Yayıncı:
University of Missouri – Columbia
Yazar(lar) :
Di Wu
Yıl :
2013
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
Pedestrian detection and counting have important application in video surveillance for entrance monitoring, customer behavior analysis, and public service management. In this thesis, we propose an accurate, reliable and fast method for pedestrian detection and counting in video surveillance. To this end, we first develop an effective method for background modeling, subtraction, update, and shadow removal. To effectively differentiate person image patches from other background patches, we develop a head-shoulder classification and detection method. A foreground mask curve analysis method is to determine the possible position of persons, and then use a SVM (Support Vector Machine) classifier with HOG (Histogram of Oriented) feature and bag of words to detect the head-shoulder of people. Based on the foreground detection and head-shoulder classification at each frame, we develop a person counting algorithm in the temporal domain to analyze the frame-level classification results. Our experiments with real-world surveillance videos demonstrate the proposed method has achieved accurate and reliable pedestrian detection and counting.
Tez türü: Thesis
Sınıflandırma :
10
Integrating plug-in electric vehicles into the electric power system
Tez

Tez
Open Access
Kaynak :
Dissertation.com
Dergi:
Iowa State University
Yayıncı:
Iowa State University
Yazar(lar) :
Di Wu
Yıl :
2012
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
This dissertation contributes to our understanding of how plug-in hybrid electric vehicles (PHEVs) and plug-in battery-only electric vehicles (EVs)—collectively termed plug-in electric vehicles (PEVs)—could be successfully integrated with the electric power system. The research addresses issues at a diverse range of levels pertaining to light-duty vehicles, which account for the majority of highway vehicle miles traveled, energy consumed by highway travel modes, and carbon dioxide emissions from on-road sources. Specifically, the following topics are investigated: (i) On-board power electronics topologies for bidirectional vehicle-to-grid and grid-to-vehicle power transfer; (ii) The estimation of the electric energy and power consumption by fleets of light-duty PEVs; (iii) An operating framework for the scheduling and dispatch of electric power by PEV aggregators; (iv) The pricing of electricity by PHEV aggregators and how it affects the decision-making process of a cost-conscious PHEV owner; (v) The impacts on distribution systems from PEVs under aggregator control; (vi) The modeling of light-duty PEVs for long-term energy and transportation planning at a national scale.
Sınıflandırma :
11
Performance studies of VoIP over Ethernet LANs
Tez

Tez
Open Access
Kaynak :
Dissertation.com
Dergi:
AUT University
Yayıncı:
AUT University
Yazar(lar) :
Di Wu
Konu :
Network infrastructure , VoIP , Ethernet LANs , Wireless
Yıl :
2009
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
Voice over Internet Protocol (VoIP) is a rapidly growing technology that enables transport of voice over data networks such as Ethernet local area networks (LANs). This growth is due to the integration of voice and data traffic (telecommunication convergence) over the existing networking infrastructure, low cost, and improved network management offered by the technology. This research investigates the performance of VoIP traffic characteristics over Ethernet LANs. In the investigation, the impact of increasing the number of VoIP clients, voice codec schemes, and traffic distribution on system performance is considered. Through various simulation experiments under realistic networking scenarios, such as small offices home offices (SOHO) and campus networks, this study provides an insight into the VoIP performance over Ethernet LANs. The simulation results indicate that all these factors can significantly affect VoIP performance over Ethernet LANs. Under both SOHO and campus network scenarios, increasing the number of VoIP clients, voice packet lengths and different traffic arrival distributions have significant impact on system performance.
Tez türü: Thesis
Sınıflandırma :
12
Segmentation, registration,and selective watermarking of retinal images
Tez

Tez
Open Access
Kaynak :
Dissertation.com
Dergi:
Texas A&M University
Yayıncı:
Texas A&M University
Yazar(lar) :
Di Wu
Konu :
segmentation , registration , watermarking , retinal imaging
Yıl :
2006
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
In this dissertation, I investigated some fundamental issues related to medical image segmentation, registration, and watermarking. I used color retinal fundus images to perform my study because of the rich representation of different objects (blood vessels, microaneurysms, hemorrhages, exudates, etc.) that are pathologically important and have close resemblance in shapes and colors. To attack this complex subject, I developed a divide-and-conquer strategy to address related issues step-by-step and to optimize the parameters of different algorithm steps. Most, if not all, objects in our discussion are related. The algorithms for detection, registration, and protection of different objects need to consider how to differentiate the foreground from the background and be able to correctly characterize the features of the image objects and their geometric properties. To address these problems, I characterized the shapes of blood vessels in retinal images and proposed the algorithms to extract the features of blood vessels. A tracing algorithm was developed for the detection of blood vessels along the vascular network. Due to the noise interference and various image qualities, the robust segmentation techniques were used for the accurate characterization of the objects?? shapes and verification. Based on the segmentation results, a registration algorithm was developed, which uses the bifurcation and cross-over points of blood vessels to establish the correspondence between the images and derive the transformation that aligns the images. A Region-of-Interest (ROI) based watermarking scheme was proposed for image authenticity. It uses linear segments extracted from the image as reference locations for embedding and detecting watermark. Global and locally-randomized synchronization schemes were proposed for bit-sequence synchronization of a watermark. The scheme is robust against common image processing and geometric distortions (rotation and scaling), and it can detect alternations such as moving or removing of the image content.
Tez türü: Book
Sınıflandırma :
13
Enhanced thermoelectric performance of Half Heulser and Silicon Germanium, and calculation on lattice thermal conductivity with Effective Medium Approach
Tez

Tez
Kaynak :
Dissertation.com
Dergi:
University of Virginia
Yayıncı:
University of Virginia
Yazar(lar) :
Di Wu
Yıl :
2013
Di Wu
Yayıncı Web Sitesi
Kaydet Alıntıla
Nanostructured Half Heusler alloys MNiSn, MCoSb (M=Hf, Zr and Ti) and SiGe nanocomposites were synthesized with high energy vibrational ball mill, followed by spark plasma sintering (SPS) consolidation. The thermoelectric properties were measured from room temperature to 1100K, the dependence of thermoelectric properties on consolidation parameters and microstructures were investigated. A differential effective medium (DEM) model was also developed to evaluate the lattice thermal conductivity in heterogeneous two-phase systems.
Tez türü: PhD
Sınıflandırma :
14
Human Action Recognition Using Deep Probabilistic Graphical Models
Tez

Tez
Open Access
Kaynak :
The Dart-Europe
Dergi:
University of Sheffield
Yazar(lar) :
Di Wu
Yıl :
2014
Di Wu
Yayıncı Web Sitesi
Kaydet Alıntıla
15
The Rogue transcriptome : using sequencing to track RNA regulation and identify unusual RNAs
Tez

Tez
Open Access
Kaynak :
Stanford University Thesis
Dergi:
Stanford University
Yayıncı:
Stanford University
Yazar(lar) :
Di Wu
Konu :
Adenosine Deaminase > metabolism, RNA > metabolism, RNA Editing, RNA Interference, RNA, Small Interfering, Caenorhabditis elegans, Heat-Shock Response, RNA-Binding Proteins, Transcriptome, Animals, Academic Dissertations, Fulltext, Internet Resources, Manuscripts, Digital, Index not Present, Genetic
Yıl :
2013
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
First, we take a look at the function of a specific type of RNA editing mediated by ADAR (adenosine deaminase that acts on RNAs). We test our hypotheses on ADAR activity and target specificity through transcriptome analysis in the context of exogenous RNAi response pathway in C. elegans. By examining of small RNA and mRNA populations in adar mutants and additional RNAi defective mutants, we show that the activity and specificity of the ADAR enzyme likely precludes the detection of its targets through conventional methods of sequence capture and analysis. Based on this understanding, we develop novel computational approaches for analysis of small RNA and mRNA populations and identify a broader set of ADAR targets, leading to a deeper understanding of the ADAR pathway, the conserved functionalities of the ADAR enzyme, and its relationship with the exogenous RNAi pathway in C. elegans. Second, we examine the dynamics of the transcriptome upon and after exposure to extreme heat. We hypothesize that the recovery response after removal from heat exposure might involve alternations in transcription regulation that are more complex than a reversal of the heat-shock induced effects, and that one such form of long-term regulation might involve the endogenous RNAi pathway and regulation via synthesis of endogenous siRNAs. By examining the dynamics of the C. elegans transcriptome during time-course of heat exposure and recovery, we reach a deeper understanding of heat shock biology and explore the relationship between endogenous siRNAs and their sequence complementary mRNA targets in the context of environmentally induced perturbance.
Sınıflandırma :
Biyotıp %98
16
The everyday life of Chinese migrants in Zambia: emotion, sociality and moral interaction
Tez

Tez
Open Access
Kaynak :
The Dart-Europe
Dergi:
London School of Economics and Political Science
Yazar(lar) :
Di Wu
Yıl :
2014
Di Wu
Yayıncı Web Sitesi
Kaydet Alıntıla
Sınıflandırma :
17
Campus emergency evacuation traffic management plan
Tez

Tez
Open Access
Kaynak :
NDTLD Thesis
Dergi:
Mississippi State : Mississippi State University,
Yayıncı:
Mississippi State : Mississippi State University,
Yazar(lar) :
Di Wu
Yıl :
2009
Di Wu
Kaydet Alıntıla
Thesis (M.S.)--Mississippi State University. Department of Civil and Environmental Engineering. / Title from title screen. Includes bibliographical references.
Sınıflandırma :
18
The role of Hh signaling in mouse retinal bipolar cell subtype development
Tez

Tez
Kaynak :
NDTLD Thesis
Dergi:
Global ETD Search
Yayıncı:
Global ETD Search
Yazar(lar) :
Di Wu
Yıl :
2017
Di Wu
Yayıncı Web Sitesi
Kaydet Alıntıla
In the vertebrate retina, bipolar interneurons consist of at least 13 distinct subtypes, which are classified based on their morphology, behavior and gene expression. The mechanisms underlying the formation of these subtypes is poorly understood. Our previous unpublished work has implicated Sonic Hedgehog (Shh) in the formation of cone and rod bipolar cell subtypes. In this thesis, I characterized the relationship between Hh signaling and bipolar subtype cell development in greater detail. Using an in vivo plasmid-based reporter approach, I show that Hh signaling is active in both retinal progenitor cells (RPCs) and bipolar cells of the postnatal retina. Next, to address function, I used a conditional gene targeting approach to show that activation of Smoothened (Smo), a downstream Hh signaling component, is both necessary and sufficient in postnatal RPCs to promote the formation of cone but not rod bipolar cells. In contrast, activation of Smo in postmitotic bipolar cells that are greater than 24 hours old from cell birth, does not affect bipolar subtype formation. Together, these results suggest that Hh signaling functions in postnatal RPCs (and potentially in early bipolar cell precursors) to promote cone bipolar cell formation. / Graduate / 2018-06-12
Anahtar Kelimeler : Retina, Bipolar cell, Sonic Hedgehog, Smoothened, Signaling, Development
Sınıflandırma :
19
Scalable multi-standard radio baseband for modern wireless communications
Tez

Tez
Open Access
Kaynak :
NDTLD Thesis
Dergi:
Linköping : Department of of Electrical Engineering, Linköping University,
Yayıncı:
Linköping : Department of of Electrical Engineering, Linköping University,
Yazar(lar) :
Di Wu
Yıl :
2009
Di Wu
Yayıncı Web Sitesi
Kaydet Alıntıla
Diss. Linköping : Linköpings universitet, 2009.
Anahtar Kelimeler : Trådlös kommunikation.
Sınıflandırma :
20
Interactions of hormones, aging and sexual experience on masculine sexual behavior and hormone receptor expression in the hypothalamus
Tez

Tez
Open Access
Kaynak :
NDTLD Thesis
Dergi:
Global ETD Search
Yayıncı:
Global ETD Search
Yazar(lar) :
Di Wu
Yıl :
2009
Di Wu
Yayıncı Web Sitesi
Kaydet Alıntıla
Age-related declines of androgens and libido in males have been observed for decades. This dissertation sought to elucidate the mechanisms by which hormones may act differentially upon their receptors in the hypothalamus of aging compared to young males. I also examined how sexual experience modulates the ability of hormones to facilitate sexual behavior with aging. Experiment one measured androgen receptors (AR) and estrogen receptor α (ERα) cells in male rats at young, middle-aged and old age. I found that AR cell numbers in hypothalamic regions studied underwent significant age-related increases. Numbers of heavily ERα labeled cells, but not total ERα cells, increased with age. This study demonstrates that the aging brain has the capacity to synthesize hormone receptors which is increased possibly due to decreased testosterone concentrations. Experiment two examined the effect of sexual experience on serum hormones and cells of AR and ERα in hypothalamic regions in young and middle-aged males. The results showed that AR cell numbers increased with aging but did not change with experience. No age- or experience-related alteration in ERα expression occurred. However, serum testosterone increased and estradiol decreased with age. Experience increased total and free testosterone. Interactions of age and experience on total testosterone, estradiol, and luteinizing hormone were found. These results show long-lasting effects of sexual experience on hormones, but not on their receptors in the hypothalamus. Experiment three investigated effects of exogenous testosterone on sexual behavior in young and middle-aged males. The results showed a decline in sexual behavior parameters with age. After castration with testosterone treatment, there were few differences in sexual behavior measures between young and middle-aged males. AR cell numbers were higher and ERα cell numbers lower in testosterone compared to vehicle-treated males of both ages, and few effects of age occurred. These findings indicate that testosterone and aging interact in a complex manner to control numbers of cells expressing hormone receptors in the brain and on the subsequent control of sexual behavior. This insight provides a better understanding of the relationship between molecular changes in the brain and behavior, and suggests new therapeutic targets to human testosterone treatment. / text
Anahtar Kelimeler : Hormones and aging, Hormone receptor expression, Androgen receptors and aging, Estrogen receptors and aging, Testosterone, effect of aging on, Male sexual experience
Sınıflandırma :
21
Cauchy problem for the incompressible Navier-Stokes equation with an external force and Gevrey smoothing effect for the Prandtl equation
Tez

Tez
Kaynak :
NDTLD Thesis
Dergi:
Global ETD Search
Yayıncı:
Global ETD Search
Yazar(lar) :
Di Wu
Yıl :
2017
Di Wu
Yayıncı Web Sitesi
Kaydet Alıntıla
Dans cette thèse on étudie des équations de la mécanique des fluides. On considère deux modèles : les équations de Navier-Stokes équation dans R3 en présence d'une force extérieure, et l'équation de Prandtl dans le demi plan. Pour le système de Navier-Stokes, on s'intéresse à l'existence locale en temps, l'unicité, le comportement global en temps et des critères d'explosion. Pour l'équation de Prandtl dans le demi plan, on s'intéresse à la régularité Gevrey. Le manuscrit est constitué de quatre chapitres. Dans le premier chapitre, on introduit quelques concepts de base sur les équations de la mécanique des fluides et on rappelle le sens physique des deux modèles précédents ainsi que quelques résultats mathématiques. Ensuite on énonce brièvement nos principaux résultats et les motivations. Enfin on mentionne quelques problèmes ouverts. Le second chapitre est consacré au problème de Cauchy pour les équations de Navier-Stokes dans R3 en présence d'une petite force extérieure, peu régulière. On démontre l'existence locale en temps pour ce système pour toute donnée initiale appartenant à un espace de Besov critique avec régularité négative. On obtient de plus trois résultats d'unicité pour ces solutions. Enfin on étudie le comportement en temps grand et la stabilité de solutions a priori globales. Le troisième chapitre traite d'un critère d'explosion pour les équations de Navier-Stokes avec une force extérieure indépendante du temps. On met en place une décomposition en profils pour les équations de Navier-Stokes forcées. Cette décomposition permet de faire un lien entre les équations forcées et non forcées, ce qui permet de traduire une information d'explosion de la solution non forcée vers la solution forcée. Dans le Chapitre 4 on étudie l'effet régularisant Gevrey de la solution locale en temps de l'équation de Prandtl dans le demi plan. Il est bien connu que l'équation de couche limite de Prandtl est instable pour des données initiales générales, et bien posée dans des espaces de Sobolev pour des données initiales monotones. Sous une hypothèse de monotonie de la vitesse tangentielle du flot, on démontre la régularité Gevrey pour la solution de l'équation de Prandtl dans le demi plan pour des données initiales dans un espace de Sobolev. / This thesis deals with equations of fluid dynamics. We consider the following two models: one is the Navier-Stokes equation in R3 with an external force, the other one is the Prandtl equation on the half plane. For the Navier-Stokes system, we focus on the local in time existence, uniqueness, long-time behavior and blowup criterion. For the Prandtl equation on the half-plane, we consider the Gevrey regularity. This thesis consists in four chapters. In the first chapter, we introduce some background on equations of fluid dynamics and recall the physical meaning of the above two models as well as some well-known mathematical results. Next, we state our main results and motivations briefly. At last we mention some open problems. The second chapter is devoted to the Cauchy problem for the Navier-Stokes equation equipped with a small rough external force in R3. We show the local in time existence for this system for any initial data belonging to a critical Besov space with negative regularity. Moreover we obtain three kinds of uniqueness results for the above solutions. Finally, we study the long-time behavior and stability of priori global solutions.The third chapter deals with a blow-up criterion for the Navier-Stokes equation with a time independent external force. We develop a profile decomposition for the forced Navier-Stokes equation. The decomposition enables us to connect the forced and the unforced equations, which provides the blow-up information from the unforced solution to the forced solution. In Chapter 4, we study the Gevrey smoothing effect of the local in time solution to the Prandtl equation in the half plane. It is well-known that the Prandtl boundary layer equation is unstable for general initial data, and is well-posed in Sobolev spaces for monotonic initial data. Under a monotonicity assumption on the tangential velocity of the outflow, we prove Gevrey regularity for the solution to Prandtl equation in the half plane with initial data belonging to some Sobolev space.
Anahtar Kelimeler : Système de Navier-Stokes, Régularité Gevrey, Critère d'explosion, Navier-Stokes systems, Blow-up criterion, Prandtl equation, Gevrey regularity
Sınıflandırma :
22
Biomolecular Tools for Noninvasive Imaging and Manipulation of Engineered Cells
Tez

Tez
Open Access
Kaynak :
NDTLD Thesis
Yazar(lar) :
Di Wu
Yıl :
2021
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
Today’s most advanced tools for imaging and controlling cellular function are based on fluorescent or light-controlled proteins, which have limited utility in large organisms or engineered living materials due to the scattering of photons. Deeply penetrant forms of energy such as magnetic fields and sound waves, while routinely used to monitor and treat diseases on the tissue and organism level, do not process the equivalent set of biomolecular tools for interfacing with biology on the molecular and cellular level. Emerging technologies discussed in this thesis aim to bridge this gap by harnessing biomolecules that have the appropriate physical properties to interact with sound waves or magnetic fields in such a way that enables the visualization and control of specific cells (Chapter 1). We describe two additions to the expanding toolkit for noninvasive imaging and control. In the first case, we show that gas vesicles, a class of hollow protein nanostructures naturally found in aquatic single-cell organisms, can be used as acoustic actuators to enable the control of cellular forces, movement, and patterning using ultrasound (Chapter 2). In the second case, we show that aquaporins, a class of membrane water channels, can be used to alter cellular permeability and serve as genetic reporters for magnetic resonance imaging (Chapter 3). These tools provide critical capabilities for interfacing with cellular function noninvasively and could open the door to applications in various research, biomedical, and industrial settings.
23
Models, optimal performances and sensitivities of commercial flight trajectory in the air traffic system
Tez

Tez
Open Access
Kaynak :
Dissertation.com
Dergi:
University of Minnesota
Yayıncı:
University of Minnesota
Yazar(lar) :
Di Wu
Yıl :
2012
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
This thesis provided systematic modeling foundation for trajectory generation of commercial aircraft flight, examined different choices of performance indices in trajectory generation within Air Traffic Control (ATC) system, and discussed sensitivity concepts to evaluate the qualities of generated optimal trajectories. The trajectory generation is typically performed by individual aircraft or their airline operation centers to optimize flight performances including flight time or flight distance. Additionally, while aircraft environmental impacts becoming a growing issue for commercial aviation, green aviation is becoming one of the most pressing issues hampering commercial aviation growth today, which also needs to be considered while generating aircraft flight trajectories. This thesis first systematically analyzes mathematical models of trajectory generation process in ATC system. Complete point-mass equations of motion within consideration of rotating spherical earth are derived. Models of motion intents and guidance strategies of flight trajectory generation are studied next, followed by the modeling of trajectory segments and their tracking objectives. This thesis lays a foundation to modeling framework for airborne flight trajectory process to support trajectory-based operations. In this thesis, trajectory generation process is formulated as a parameter optimal control problem in consistence with ATC procedures. A gradient algorithm is devised for obtaining numerical solutions. Climb and descent phases are first studied separately, and are then combined, together with cruise phase, to examine complete trajectories from liftoff to touchdown. For climb, decent, and the entire flight, optimal trajectories are calculated that respectively minimize flight time, fuel consumption, emissions, and when applicable, distance traveled, and these optimal trajectories are compared for their trade-offs. Next, to evaluate qualities of generated optimal trajectories, two sensitivity concepts are used. Open-loop sensitivities measure changes of generated trajectories due to modeling errors, and reflect reliability of the trajectory generation process. In contrast, closed-loop sensitivities measure deviations of actual trajectories from generated trajectories caused by modeling errors and/or flight conditions, where actual trajectories are obtained with the pilots or autopilots actively tracking flight objectives extracted from the generated trajectories. They reflect trajectory predictability. In this thesis, closed-loop sensitivities are computed with respect to potential uncertainties of vertical wind speed.
Tez türü: Thesis or Dissertation
Sınıflandırma :
24
A layered sodium titanate as promising anode material for sodium ion batteries
Tez

Tez
Open Access
Kaynak :
Dissertation.com
Dergi:
Dissertation.com
Yayıncı:
Dissertation.com
Yazar(lar) :
Di Wu
Konu :
Mechanical Engineering.
Yıl :
2014
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
Sodium ion batteries have recently received great attention for large-scale energy applications because of the abundance and low cost of sodium source. Although some cathode materials with desirable electrochemical properties have been proposed, it's quite challenging to develop suitable anode materials with high energy density and good cyclability for sodium ion batteries. Herein, we report a layered material, 03-NaTiO2, that delivers 130mAhg-1 of reversible capacity and presents excellent cyclability with capacity retention over 97.5% after 40 cycles and high rate capability. Furthermore, by coupling the electrochemical process with in situ X-ray diffraction, the structure evolution and variation of cell parameters corresponding to an 03-03' phase transition during sodium deintercalation is investigated. Unusual lattice parameter variation was observed by in situ XRD, which can be related to the structure modulation with varying Na vacancy ordering. An irreversible structural modification upon overcharging is also confirmed by in situ XRD. In summary, our work demonstrates that 03-NaTiO2 is a very promising anode material for sodium ion batteries with high energy density.
Tez türü: Thesis
Sınıflandırma :
Kimya %94
Elektrokimya %100
25
Infants??? reasoning about self-propelled objects, agents, and animals
Tez

Tez
Open Access
Kaynak :
Dissertation.com
Dergi:
University of Illinois – Urbana-Champaign
Yayıncı:
University of Illinois – Urbana-Champaign
Yazar(lar) :
Di Wu
Konu :
causal reasoning , self-propelled object , agent , animal , infant
Yıl :
2011
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
In the present research, we investigated young infants??? concepts of self-propelled object, agent, and animal through three research projects. In Chapter 2, we examined infants??? concept of self-propelled object, specifically, whether 5-month-olds expect a self-propelled object to produce changes in its parts. We found that 5-month-olds understand that a self-propelled object can use its internal energy to produce orientation and position changes but not location and appearance changes in its parts. In Chapter 3, we examined infants??? concept of agent, particularly, whether infants believe that an agent can be inert. The results indicated that 14-month-olds believe that an agent can be inert, suggesting that self-propulsion is not necessary for infants to identify an object as an agent. In Chapter 4, we asked whether infants have any quasi-biological expectations about animals. The results suggest that 7-month-olds expect the inside of an animal to be full as opposed to be hollow. Together, these results support the core-concept view which states that infants divide objects into broad, abstract categories in accordance with the causal principles in specific reasoning domains.
Sınıflandırma :
26
Provision of outreach dental service and caries risk assessment to preschool children in Hong Kong
Tez

Tez
Open Access
Kaynak :
Dissertation.com
Dergi:
University of Hong Kong
Yayıncı:
University of Hong Kong
Yazar(lar) :
Di Wu
Konu :
Preschool children - Dental care - China - Hong Kong. , Dental hygiene - China - Hong Kong. , Dental caries - China - Hong Kong.
Yıl :
2011
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
published_or_final_version Dentistry doctoral Doctor of Philosophy
Tez türü: PhD
Sınıflandırma :
27
A Novel Method to Prepare Silica Based Carbon Dioxide Capture Sorbent
Tez

Tez
Open Access
Kaynak :
Dissertation.com
Dergi:
University of Akron
Yayıncı:
University of Akron
Yazar(lar) :
Di Wu
Yıl :
2008
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
An innovative preparation method is developed to highly improve the carbon dioxide capture capacity of the silica sorbents. In the previously used sorbent treatment method, free hydroxyl groups of silica available for further reaction are obtained by silica dehydration at high temperature. This new approach, however, grafts tetraethylenepentamine (TEPA) onto silica surface directly via incipient wetness impregnation (IWI) of TEPA/ethanol solutions at room temperature. The CO2 adsorption/desorption performance of the catalysts is studied by Diffused Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and Mass Spectrometer (MS) spectroscopy both qualitatively and quantitatively. The concentration of TEPA/ethanol solutions influences the deposit process of pentamine molecules onto silica particles by controlling the concentration differential of TEPA between the bulk solution and the surface layer. Samples treated with more concentrated solutions had higher maximum carbon dioxide adsorption values, calculated from the calibrated CO2 desorption peak area of MS spectra. The loading amount of solution also affects the mass transfer rate and equilibrium of TEPA. After the concentration is equilibrated between the bulk and the surface, the system lost the concentration gradient between bulk solution and silica surfaces, excessive pentamine solution removes the grafted pentamine molecules, and makes the carbon dioxide capture capacity curve drop from the peak point. The 0.03g silica treated by 2%, 10% and 20% TEPA/EtOH solution got the CO2 adsorption capacity of 1545.03, 4590.28 and 7674.99 µmol/g-sorbent, respectively. Two pretreatment methods of silica sorbents, ethanol pretreatment and carbon dioxide pretreatment, are used to further enhance the adsorption performance. In the former pretreatment, ethanol solvent is injected before each injection of TEPA solution, and in the latter, TEPA solution is injected in the atmosphere of a carbon dioxide gas. The principles behind these pretreatments underlie mass and momentum transfer processes. After the injection of TEPA/ethanol solution, the TEPA layer on silica surface becomes more and more concentrated with the solvent evaporation. Pores and channels are likely to be blocked by the high viscous TEPA on silica surfaces. Sufficient solvent molecules in the ethanol pretreatment help more than keep the concentration gradient between the bulk and surface and maintain a driving force to deposit the TEPA onto silica surfaces, an appropriate viscosity assists TEPA molecules diffuse deeper. 0.03g silica at the loading of 200 µl, 20% TEPA/EtOH solution, the maximum CO2 adsorption capacity is 8362.36 µmol/g-sorbent with Ethanol pretreatment approach. The grafted pentamine molecules on silica surface can form inter-molecular H-bonds, which consume the functional amine groups and reduce the surface area available for CO2 capture. Carbon dioxide was used to protect these free NH groups in the carbon dioxide pretreatment. DRIFTS and MS spectroscopy analysis shows either way gives…
Tez türü: MS
Sınıflandırma :
28
Atomization Model Development for Fire Suppression Devices
Tez

Tez
Open Access
Kaynak :
Dissertation.com
Dergi:
University of Maryland
Yayıncı:
University of Maryland
Yazar(lar) :
Di Wu
Konu :
Engineering, General , Engineering, Industrial
Yıl :
2005
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
The performance of water-based fire suppression systems is governed by the dispersion of the droplets in the spray. Characterization of the spray is essential for predicting and evaluating the performance of these suppression systems. The accuracy of the spray characterization is quite sensitive to the initial spray specification when using particle tracking method to model spray dispersion. An atomization model based on first principles has been developed for predicting the distributed properties for the initial spray. Inputs to this model include injector geometry, operating conditions, and suppressant fluid properties. This modeling approach has also been integrated with drop dispersion models in FDS 4.0 to characterize spray dispersion behavior. The effect of initial spray specification on spray dispersion behavior in a quiescent environment has also been addressed. The drop size predictions using the proposed atomization model have demonstrated favorable agreement with actual sprinkler spray measurements over a range of operating conditions.
Tez türü: Thesis
Sınıflandırma :
29
Sequence design with applications to ultra-wideband communication systems
Tez

Tez
Open Access
Kaynak :
Dissertation.com
Dergi:
Rutgers University
Yayıncı:
Rutgers University
Yazar(lar) :
Di Wu
Yıl :
2007
Di Wu
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
To enable high data rate target applications in a typical ultra-wideband (UWB) dense multipath channel, DS-UWB signaling suffers from a severe inter-symbol-interference (ISI) and multiple access interference (MAI). In an attempt to avoid complexity at the receiver, we tackle these problems from the transmitter side and consider ternary sequence based UWB (TS-UWB) signaling as a unifying descriptor of a number of impulse-based UWB schemes. We propose a technique which employs ternary complementary sets to improve the performance of orthogonal pulse based multi-channel UWB systems. By assigning mutually orthogonal (MO) complementary sets to the users, both MAI and multipath interference can be significantly suppressed. One of the major impediments to deploying such systems is a high peak-to-average power ratio (PAPR). We show that PAPR can be upper bounded by an autocorrelation merit function of column sequences of the corresponding complementary set matrix. Hence, we propose a design of complementary sets satisfying a column correlation constraint. The design algorithm recursively builds a collection of MO complementary set matrices starting from a companion pair of sequences. We relate correlation properties of column sequences to that of the companion pair and illustrate how to select an appropriate companion pair to ensure that a given column correlation constraint is satisfied. To support high-speed and multirate data services, we construct ternary orthogonal variable spreading factor (OVSF) code with a zero-correlation zone (ZCZ). Compared to the conventional Walsh code based OVSF code, the proposed ZCZ-OVSF code maintains its code orthogonality even in a multipath channel or when synchronism is lacking and, thus, is suitable for quasi-synchronous (QS) TS-UWB systems. We further propose an adaptive data rate transmission scheme which maximizes the uplink aggregate throughput of the system by allocating OVSF codes to the active users based on their signal to interference and noise ratios (SINR). Finally, we propose an adaptive transmission approach that suggests selecting a ternary beamforming sequence for a TS-UWB signal based on the signs of the reflection coefficients corresponding to a few strongest paths so that the signal energy at the output of the simple non-adaptive receiver is enhanced.
Tez türü: PhD
Sınıflandırma :

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