教学课程资源库 更多>>

关键词： Kinematics   Control algorithms   Planning   Traffic accidents & safety   Autonomous vehicles   Sensors   Neural networks   Roads & highways   Controllers   Artificial intelligence   Computer science   Mechanics   Physics   Transportation  

摘要： Autonomous driving technologies have been developed in the past decades with the objective of increasing safety and efficiency. However, in order to enable such systems to be deployed on a global scale, the problems and concerns regarding safety must be addressed. The difficulty in providing safety guarantees for autonomous driving applications comes from the fact that the self-driving vehicle needs to be able to handle a diverse set of environments and traffic situations. More specifically, it must be able to interact with other road users, whose intentions cannot be perfectly known. This thesis proposes a Model Predictive Control (MPC) approach to ensure safe autonomous driving in uncertain environments. While MPC has been widely used in motion planning and control for autonomous driving applications, the standard literature cannot be directly applied to ensure safety (recursive feasibility) in the presence of other road users, i.e., pedestrians, cyclists, and other vehicles. To that end, this thesis shows how recursive feasibility can still be obtained through a slight modification of the MPC controller design. The results of this thesis build upon the assumption that the behavior of the surrounding environment can be predicted to some extent, i.e., a future motion trajectory with some uncertainty bound can be propagated. Then, by postulating the existence of a safe set for the autonomous driving problem, and requiring that the motion prediction models have a consistent structure, safety guarantees can be derived for an MPC controller. Finally, this thesis shows that the proposed MPC framework does not only hold in theory and simulations, but that it can also be deployed on a real vehicle test platform and operate in real-time, while still ensuring that the conditions needed for the derived safety guarantees hold.

关键词： Internet of Things   Traffic flow   Algorithms   Cloud computing   Performance evaluation   Bandwidths   User satisfaction   Software services   Computer science   Transportation   Web studies  

摘要： The Internet of Things (IoT) paradigm is paving the way for many new emerging technologies, such as smart grid, industry 4.0, connected cars, smart cities, etc. Mobile Edge Computing (MEC) provides promising solutions to reduce service delays for delay-sensitive IoT applications, where cloudlets are co-located with wireless access points in the proximity of IoT devices. Most mobile users have specified Service Function Chain (SFC) requirements, where an SFC is a sequence of Virtual Network Functions (VNFs). Meanwhile, edge intelligence arises to provision real-time deep neural network (DNN) inference services for users. To accelerate the processing of the DNN inference of a request in an MEC network, the DNN inference model usually can be partitioned into two connected parts: one part is processed on the local IoT device of the request; and the other part is processed on a cloudlet (server) in the MEC network. Also, the DNN inference can be further accelerated by allocating multiple threads of the cloudlet in which the request is assigned. In this thesis, we will focus on virtual service provisioning for IoT applications in MEC Environments. Firstly, we consider the user satisfaction problem of using services jointly provided by an MEC network and a remote cloud for delay-sensitive IoT applications, through maximizing the accumulative user satisfaction when different user services have different service delay requirements. A novel metric to measure user satisfaction of using a service is proposed, and efficient approximation and online algorithms for the defined problems under both static and dynamic user service demands are then devised and analyzed. Secondly, we study service provisioning in an MEC network for multi-source IoT applications with SFC requirements with the aim of minimizing service provisioning cost, where each IoT application has multiple data streams from different sources to be uploaded to the MEC network for processing and storage, while each dat

关键词： Decomposition   Dynamic programming   Algorithms   Graphs   Traveling salesman problem   Computer science   Operations research  

摘要： Many important graph problems are NP-complete. The complexity analysis relies on the worst-case scenario. However, most of the times the input has a nice “structure” so that we can solve the problem much faster, compared to the other inputs of the same size. In parameterized complexity, we classify the problems finer than the traditional setting. In order to do so, we define the complexity as a function of the set of the (input or output) parameters and the size of the input itself rather than as a function of the size of the input alone. Fixed-parameter tractable problems are the problems that can be solved in time O(f(k)poly(n)), where f(·) is a computable function, k is the parameter, and n is the input size. If the parameter is fixed, then the problem becomes tractable since the dependence on n is only polynomial. Many NP-complete problems are known to be FPT. This means, if the parameter is bounded, then we can solve them relatively fast, which is the case in many applications. Courcelle’s metatheorem states that any graph property which can be described in the monadic second-order logic of the graphs can be decided in linear time if the treewidth (the parameter in this case) is bounded. There are three concerns that we address. First, we need to prove that the treewidth is bounded. The bad news is that the treewidth problem itself is NP-complete but FPT. Then, we have to find a tree decomposition with bounded treewidth to be able to apply dynamic programming. Finally, when we apply dynamic programming, most of the time we end up using exponential space. In this work, we solve all the above issues and start by presenting a 5-approximation algorithm solving the treewidth problem in time O(28.765kn log n), which can be used in application1 . Later on we further improve this result by introducing new notion called “leftmost separator”. The improved algorithm runs in time O(26.755k (log k) √ kn log n). Both of our algorithms check if the treewidth is at most k. If

关键词： Evolution and Development   Animal sciences   Biochemistry   Bioinformatics   Botany   Cellular biology   Chemistry   Computer science   Developmental biology   Genetics  

摘要： Genome and environment together greatly influence how an organism develops and functions. Cattle is a livestock species with high economic significance; thus, deciphering how its genome and genomic information relates to its phenotype is crucial. Nevertheless, our understanding of bovine genomes is incomplete: investigation of bovine genomes thus far has mainly focused on single-nucleotide variants, leaving complex and less tractable variants, such as structural variants, underexplored. In this thesis, I present a comprehensive and in-depth investigation of structural variants in bovine genomes. Two structural variant catalogues, generated from genotyping data and deeply sequenced bovine genomes, revealed ~32 and ~5,000 SVs per genome, respectively. Furthermore, I integrated statistical associations and ~omics data, and delineated a 12-Kb copy number variant (CNV) as the likely causal variant of a major clinical mastitis QTL. This CNV encompasses an enhancer that targets the group-specific component gene, which encodes a vitamin D binding protein. Lastly, I investigated the emergence of de novo structural variants by exploiting 127 multi-generational deeply sequenced genomes. The pedigree-based germline mutation rate corresponded to one de novo structural variant per 8.5 births. The de novo structural variants were strongly biased towards male germlines and in vitro produced animals, unravelling sex and reproductive technology effects. Together, this thesis highlights a broad spectrum of bovine structural variants: from extremely rare de novo mutations to population variants, highlighting one that exerts strong effects on economically important traits. This thesis contributes to advancing our understanding of bovine structural variation.

关键词： 计算机系统   信息技术   工程建设   优化资源配置  

摘要： 阐述计算机科学与技术在工程建设项目中的特点、应用实践、应用策略，探讨工程建设项目的高质量管理与企业和国家的发展相关，它需要先进的计算机科学和技术来提升质量管理效率，优化资源配置，从而在工程建设项目在现代化、信息化的进程中给予足够的技术支撑。

关键词： Internet of Things   Photovoltaic cells   Sensors   Chemical vapor deposition   Cellular biology   Computer science   Materials science   Web studies  

摘要： On-chip sensing and communications in the Internet of things platform have benefited from the miniaturization of faster and low power complementary-metal-oxide semiconductor (CMOS) microelectronics. Micro-electromechanical systems technology (MEMS) and development of novel nanomaterials have further improved the performance of sensors and transducers while also demonstrating reduction in size and power consumption. Integration of such technologies can enable miniaturized nodes to be deployed to construct wireless sensor networks for autonomous data acquisition. Their longevity, however, is determined by the lifetime of the power supply. Traditional batteries cannot fully fulfill the demands of sensor nodes that require long operational duration. Thus, we require solutions that produce their own electricity from the surroundings and store them for future utility. Furthermore, manufacturing of such a power supply must be compatible with CMOS and MEMS technology. In this thesis, we will describe on-chip electrochemical capacitors and piezoelectric energy harvesters as components of such a self-powered sensor node. Our piezoelectric microcantilevers confirm the feasibility of fabricating micro electro-mechanical-systems (MEMS) size two-degree-of-freedom systems which can address the major issue of small bandwidth of piezoelectric micro-energy harvesters. These devices use a cut-out trapezoidal cantilever beam, limited by its footprint area i.e. a 1 cm2 silicon die, to enhance the stress on the cantilever’s free end while reducing the gap remarkably between its first two eigenfrequencies in the 400 - 500 Hz and in the 1 - 2 kHz range. The energy from the M-shaped harvesters could be stored in rGO based on-chip electrochemical capacitors. The electrochemical capacitors are manufactured through CMOS compatible, reproducible, and reliable micromachining processes such as chemical vapor deposition of carbon nanofibers (CNF) and spin coating of graphene oxide based (GO) solut

关键词： Energy   Analytical chemistry   Chemistry   Computer science   Military history   Optics  

摘要： Modern microelectronics seeks to miniaturize transistors and follows Moore’s Law, seeking faster logic, lower power usage, and denser storage. Progress in this direction can no longer rely on traditional techniques and materials, as fundamental limits to materials become more significant as devices shrink. In this dissertation I present work I carried out in collaboration with other researchers, which includes crystal characterization and transport measurements on two layered indium-selenium compounds featuring van der Waals interlayer coupling, γ-InSe and α-In2Se3, that may provide new avenues to advance microelectronics. I first review back ground information on semiconductors, field effect transistors, ferroelectricity, and layered transition metal chalcogenides. I summarize experimental methods including device preparation and measurements. I then present our work on α-In2Se3 ferroelectric-field effect transistors (FeSmFET). The devices are prepared from mechanically exfoliated ultrathin crystals, using α-In2Se3 for the channel layer. Contact to the crystal was done using a novel photolithography process and metal evaporation. In traditional ferroelectric field effect transistors the semiconducting channel is controlled using a ferroelectric-dielectric, this is reversed in a FeSmFET where the channel is a ferroelectric semiconductor. I present results of our transport measurements on the FeSmFET devices, evidence for polarization-controlled behavior and evidence for an electric-field-induced metallic state in thin crystals of α-In2Se3. Magneto electrical transport measurements revealed the effect of weak localization and high carrier densities in the metallic state. I also present our work on molecular beam epitaxy (MBE) grown films of γ-InSe on GaAs. Raman spectroscopy, X-ray diffraction, and transmission electron microscopy were used to characterize these films. Hall bar devices were then fabricated using photolithography and plasma etching. These films were f

关键词： Analytical chemistry   Biochemistry   Bioengineering   Chemistry   Computer science   Engineering   Genetics   Law enforcement   Organic chemistry  

摘要： Mitochondrial DNA (mtDNA) analysis has several forensic applications such as criminal investigations, identification of human remains, and missing person investigations. It is also the only type of DNA that is available from certain sample types such as hair shafts. The presence of mtDNA heteroplasmy within and between tissue types can lead to mtDNA sequence differences when comparing samples originating from the same individual. Studies on mtDNA heteroplasmy are increasingly being carried out for their implications in forensic interpretation of mtDNA sequences. Specifically, mtDNA in buccal swabs compared to hair samples from one individual may show differences in sequence due to heteroplasmy, and casework samples compared to reference swabs may exhibit differences that must be correctly interpreted to prevent faulty conclusions made by investigators and scientists alike. Establishing expected rates of heteroplasmy in mtDNA extracted from hair shaft samples and comparison to mtDNA extracted from buccal swab samples will lead to increased confidence in mtDNA interpretation. The goals of this study were to (1) successfully sequence the entire mtDNA control region from buccal swab samples from 5 volunteers using Sanger sequencing, (2) amplify smaller (<300bp) sections of overlapping regions of the mtDNA control region from 15-20 hair shafts collected from three areas of the scalp using three methods of DNA extraction, and (3) evaluate mtDNA sequences from hair shafts and buccal swabs to identify heteroplasmy within and between samples. Overall, only 20% of the extracted hair samples resulted in half of Hypervariable Region 1 (HV1) being successfully sequenced from either the 5´ or 3´ end. Two out of five participants showed length heteroplasmy in the poly-cytosine region beginning at position 303 within the HV2 region. Point heteroplasmy was observed in one participant at one position in the buccal swab (nucleotide position 16093) as well as at two different positions

关键词： Software   Older people   Sensors   Traumatic brain injury   Aging   Computer science   Gerontology   Medicine   Neurosciences  

摘要： Balance maintenance is crucial to participating in the activities of daily life. Balance is often considered as the ability to maintain the centre of mass (COM) position within the base of support. Primarily, to maintain balance, reliance is placed on the balance related sensory systems i.e., the visual, proprioceptive and vestibular. Several factors can affect a person’s balance such as neurological diseases, ageing, medication and obesity etc. To gain insight into the balance operations, studies rely on statistical and machine learning techniques. Statistical techniques are used for inferencing while machine learning techniques proved effective for interpretation. The focus of this study was on the issues encountered in human balance analysis such as the quantification of balance by relevant features, the relationships between COM and ground projected body sway, the performance of various sensory systems in balance analysis, and their relationships between the directions of body sway (i.e., mediolateral (ML) and anteriorposterior (AP)). A portable wireless accelerometry device was developed, balance analysis methods based on the inverted pendulum were devised and evaluated for their accuracy and reliability against a setup designed to allow manual balance measurements. Balance data were collected from 23 healthy adult subjects with the mean (standard deviation) of the age, height and weight: 24.5 (4.0) years, 173.6 (6.8) cm, and 72.7 (9.9) kg respectively. The accelerometry device was attached to the subjects at the approximate position of the illac crest, while they performed 30 seconds trials of the four conditions associated with a standard balance test called the modified Clinical Test of Sensory Interaction and Balance (mCTSIB). These required standing on a hard (ground) surface with the eyes open, standing on hard surface with the eyes closed, standing on a compliant surface (sponge, 10 cm thick) with the eyes open and standing on a compliant surface with th

摘要： Software engineering is a growing field, with ever-increasing demand for capable engineers who can design, implement, and test the software that is needed for the modern world. With this increasing demand for software engineers, there is a corresponding increase in the demand placed on computer science programs that graduate these engineers. However, the increase in undergraduate enrollment in computer science programs has generally outpaced the increase in instructors. Unfortunately, this can have negative educational impacts by reducing the support that instructors can offer each student. Automation has resulted in significant benefits, allowing developers to work more efficiently and deliver higher-quality software, but automation is not as prevalent within computer science education as it is within industry. To help promote better educational outcomes, particularly by improving the feedback that students receive on their work, I adopt software engineering automation techniques into computer science education and evaluate their efficacy. With ever more students enrolled in computer science programs comes a more widespread use of team-based learning (TBL) and larger teams. While TBL has numerous educational benefits, it is not an educational panacea. Larger teams increases the risk of team challenges, including ineffective communication and non-participation, which has the potential to hamper educational outcomes. To address this, I propose and evaluate using survey techniques to gain insights into how teams work and the challenges that students face in this environment, and enable just-in-time support for struggling teams. This approach can provide instructors with feedback on team challenges, and also encourages self-reflection on the part of students. Together, these approaches support my thesis: Using software engineering automation and survey techniques in computer science education results in improved student learning outcomes, early prediction of struggling