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关键词： Convolution   Computer architecture   Estimation   Feature extraction   Kernel   Computer science   Annotations   Surveillance   neural network   supervised learning  

摘要： Crowd counting is critical for numerous video surveillance scenarios. One of the main issues in this task is how to handle the dramatic scale variations of pedestrians caused by the perspective effect. To address this issue, this paper proposes a novel convolution neural network-based crowd counting method, termed Perspective-guided Fractional-Dilation Network (PFDNet). By modeling the continuous scale variations, the proposed PFDNet is able to select the proper fractional-dilation kernels for adapting to different spatial locations. It significantly improves the flexibility of the state-of-the-arts that only consider the discrete representative scales. In addition, by avoiding the multi-scale or multi-column architecture that used in other methods, it is computationally more efficient. In practice, the proposed PFDNet is constructed by stacking multiple Perspective-guided Fractional-Dilation Convolutions (PFC) on a VGG16-BN backbone. By introducing a novel generalized dilation convolution operation, the PFC can handle fractional dilation ratios in the spatial domain under the guidance of perspective annotations, achieving continuous scales modeling of pedestrians. To deal with the problem of unavailable perspective information in some cases, we further introduce an effective perspective estimation branch to the proposed PFDNet, which can be trained in either supervised or weakly-supervised setting once the branch has been pre-trained. Extensive experiments show that the proposed PFDNet outperforms state-of-the-art methods on ShanghaiTech A, ShanghaiTech B, WorldExpo'10, UCF-QNRF, UCF_CC_50 and TRANCOS dataset, achieving MAE 53.8, 6.5, 6.8, 84.3205.8, and 3.06 respectively.

摘要： This integrated article thesis provides an analysis of the past, present, and potential future state of Computer Science (CS) in K-12 education. Once implemented in optional courses at the secondary level, CS concepts and skills are now being integrated into other subject areas such as mathematics, science, and technology and other grades including K-8. This new state of K-12 CS education is explored through an analysis of 1) related theory reflected in the literature, 2) historical secondary school CS curriculum, 3) enrolment data and important issues related to equity, diversity, and inclusion, and 4) K-8 CS-related curriculum approaches currently being implemented in educational jurisdictions across Canada. The four articles in this dissertation employ a qualitative approach to research, drawing on a constructivist epistemology. Thematic Analysis is used in the comparative analysis of historical curriculum documents from Ontario and Document Analysis is used in comparing the various K-8 curriculum documents from across Canada. Together, the chapters included in this integrated article thesis provide a comprehensive analysis of K-12 CS education that supports educators, policy makers, and researchers in the field during a transformative time.

关键词： Bibliometric Analysis   Computer Science   Requirements Engineering   Software Engineering   Systems Development  

摘要： Requirements engineering (RE) is gaining acceptance by industries and practitioners as a significant process in systems development. Similarly, the publications on the research related to the RE topic progress. However, there is a lack of study on the progressions of this research based on a bibliographic portfolio. This paper presents the emergence of the RE field and mapping the state of the art of scientific production using a bibliometric survey approach. This study identifies the research trends based on the observations of scientific production over the past two decades. Quantitative and qualitative information in requirements engineering research through various bibliographic attributes are presented, such as the leading journals, top-cited articles, top authors, and top countries. Research trends in RE can be observed based on the number of research themes, and the involvement of various disciplines from RE were not acknowledged until this study was conducted. The results provide evidence and an overview of future directions in this research field.

关键词： Manifolds   Tensors   Linear programming   Laplace equations   Hyperspectral imaging   Computer science   Training   Hyperspectral image classification   low-rank   superpixel segmentation   superpixel-guided locality preserving graph  

摘要： Given the detrimental effect of spectral variations in a hyperspectral image (HSI), this article investigates to recover its discriminative representation to improve the classification performance. We propose a new method, namely local low-rank approximation with superpixel-guided locality preserving graph (LLRA-SLPG), which can reduce the spectral variations and preserve the local manifold structure of an HSI. Specifically, the LLRA-SLPG method first clusters pixels of an HSI into several groups (i.e., superpixels). By taking advantage of the local manifold structure, a Laplacian graph is constructed from the superpixels to ensure that a typical pixel should be similar to its neighbors within the same superpixel. The LLRA-SLPG model can increase the compactness of pixels belonging to the same class by reducing spectral variations while promoting local consistency via the Laplacian graph. The objective function of the LLRA-SLPG model can be solved efficiently in an iterative manner. Experimental results on four benchmark datasets validate the superiority of the LLRA-SLPG model over state-of-the-art methods, particularly in cases where only extremely few training pixels are available.

关键词： Output feedback   Control design   Process control   Observability   Feedforward systems   Context modeling   Computer science   Nondeterministic finite state systems   reachability   output feedback control  

摘要： In this letter control design of nondeterministic finite state systems with reachability specifications is addressed. The class of controllers we use is rather general and combines feedforward and output feedback schemes. The proposed controller allows not only the state of the system to reach the desired target set but also the identification of which state of the target set has been reached. Necessary and sufficient conditions are derived for the control problem to admit a solution and a controller is designed. The solution to the investigated problem has important implications in the context of recovery control and symbolic control design of nonlinear and hybrid systems, as discussed also through some examples.

关键词： Consensus protocol   Protocols   Hospitals   Robustness   Scalability   Distributed ledger   Computer science   Blockchains   consensus protocol   electronic healthcare  

摘要： Blockchain is an emerging distributed and decentralized technology that promises to revolutionize the healthcare sector by securely storing and maintaining incorruptible electronic health record data. Consensus protocols are at the core of blockchain technology. They establish security and integrity in the system by ensuring that the majority of miners are in agreement on all transactions and blocks added to the distributed ledger. While many consensus protocols have been proposed, most of them require heavy computation and are not scalable. In this work, we propose a novel permissioned consensus protocol, named ACCORD, a multi-leader (quorum-based) protocol that achieves fork-resistance, robustness, and scalability. To achieve this, ACCORD consists of three distinct components: 1) an asynchronous quorum selection procedure to designate the creators of future blocks;2) a block creation protocol run by the quorum to prevent omissions in the presence of honest quorum members;and 3) a decentralized arbitration protocol to ensure consensus by voting. Additionally, we implemented the protocol and conducted experiments to demonstrate scalability, robustness, and fairness.

关键词： Cultural differences   Social networking (online)   Approximation algorithms   Computer science   Task analysis   Resource management   Greedy algorithms   Information propagation   diversity maximization   filter bubbles   social influence  

摘要： Social-media platforms have created new ways for citizens to stay informed and participate in public debates. However, to enable a healthy environment for information sharing, social deliberation, and opinion formation, citizens need to be exposed to sufficiently diverse viewpoints that challenge their assumptions, instead of being trapped inside filter bubbles. In this paper, we take a step in this direction and propose a novel approach to maximize the diversity of exposure in a social network. We formulate the problem in the context of information propagation, as a task of recommending a small number of news articles to selected users. In the proposed setting, we take into account content and user leanings, and the probability of further sharing an article. Our model allows to capture the balance between maximizing the spread of information and ensuring the exposure of users to diverse viewpoints. The resulting problem can be cast as maximizing a monotone and submodular function, subject to a matroid constraint on the allocation of articles to users. It is a challenging generalization of the influence-maximization problem. Yet, we are able to devise scalable approximation algorithms by introducing a novel extension to the notion of random reverse-reachable sets. We experimentally demonstrate the efficiency and scalability of our algorithm on several real-world datasets.

关键词： Popular works.   Social aspects   Computer science   Popular works.   Computer programming  

ISBN: (数字)9780691230818 ISBN: (纸本)9780691208480

摘要： Leading technologists, historians, and journalists reveal the stories behind the computer coding that touches all aspects of life—for better or worseFew of us give much thought to computer code or how it comes to be. The very word “code” makes it sound immutable or even inevitable. “You Are Not Expected to Understand This” demonstrates that, far from being preordained, computer code is the result of very human decisions, ones we all live with when we use social media, take photos, drive our cars, and engage in a host of other *** from law enforcement to space exploration relies on code written by people who, at the time, made choices and assumptions that would have long-lasting, profound implications for society. Torie Bosch brings together many of today’s leading technology experts to provide new perspectives on the code that shapes our lives. Contributors discuss a host of topics, such as how university databases were programmed long ago to accept only two genders, what the person who programmed the very first pop-up ad was thinking at the time, the first computer worm, the Bitcoin white paper, and perhaps the most famous seven words in Unix history: “You are not expected to understand this.”This compelling book tells the human stories behind programming, enabling those of us who don’t think much about code to recognize its importance, and those who work with it every day to better understand the long-term effects of the decisions they *** an introduction by Ellen Ullman and contributions by Mahsa Alimardani, Elena Botella, Meredith Broussard, David Cassel, Arthur Daemmrich, Charles Duan, Quinn DuPont, Claire L. Evans, Hany Farid, James Grimmelmann, Katie Hafner, Susan C. Herring, Syeda Gulshan Ferdous Jana, Lowen Liu, John MacCormick, Brian McCullough, Charlton McIlwain, Lily Hay Newman, Margaret O’Mara, Will Oremus, Nick Partridge, Benjamin Pope, Joy Lisi Rankin, Afsaneh Rigot, Ellen R. Stofan, Lee Vinsel, Josephine Wolff, and Ethan Zucke

关键词： Cryptography   Cloud computing   Computer science   Social networking (online)   Privacy   Data models   Urban areas   Cloud-based graph analytics   attributed subgraph matching   privacy preservation   oblivious services  

摘要： In recent years there has been growing popularity of leveraging cloud computing for storing and querying attributed graphs, which have been widely used to model complex structured data in various applications. Such trend of outsourced graph analytics, however, is accompanied with critical privacy concerns regarding the information-rich and proprietary attributed graph data. In light of this, we design, implement, and evaluate OblivGM, a new system aimed at oblivious graph analytics services outsourced to the cloud. OblivGM focuses on the support for attributed subgraph matching, one popular and fundamental graph query functionality aiming to retrieve from a large attributed graph subgraphs isomorphic to a small query graph. Built from a delicate synergy of insights from attributed graph modelling and advanced lightweight cryptography, OblivGM protects the confidentiality of data content associated with attributed graphs and queries, conceals the connections among vertices in attributed graphs, and hides search access patterns. Meanwhile, OblivGM flexibly supports oblivious evaluation of varying subgraph queries, which may contain equality and/or range predicates. Extensive experiments over a real-world attributed graph dataset demonstrate that while providing strong security guarantees, OblivGM achieves practically affordable performance (with query latency on the order of a few seconds).

关键词： Computer science education   Culturally responsive computing   Rural education  

摘要： Students from rural places participate in computer science less than their urban and suburban peers (Google & Gallup, 2016). While current research into this phenomenon is in its infancy, research of other underrepresented populations has indicated utilizing culturally responsive computing may increase participation. In rural Nebraska and in much of the Midwest, agriculture is a very important cultural pillar. Accordingly, this thesis looks for potential overlap between computer science education and agriculture education. Eleven teachers were interviewed and ninety teachers were surveyed about their experiences with computer science applications in agriculture. Ultimately, the support for increased CS applications in agriculture classrooms is nearly universal, but teachers do point out some possible obstacles in implementing cross-curricular experiences. There is optimism that giving students hands-on experiences with modern computer-based agriculture technology may be a culturally responsive way to generate rural student interest in CS.