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关键词： CS   unplugged   programming   coding   systematic review  

摘要： The computer science (CS) unplugged approach intends to teach CS concepts and computational thinking skills without employing any digital tools. The current study conducted a systematic literature review to analyze research studies that conducted investigations related to implementations of CS unplugged activities. A systematic review procedure was developed and applied to detect and subsequently review relevant research studies published from 2010 to 2019. It was found that 55 research studies (17 articles + 38 conference proceedings) satisfied the inclusion criteria for the analysis. These research studies were then examined with regard to their demographic characteristics, research methodologies, research results, and main findings. It was found that the unplugged approach was realized and utilized differently among researchers. The majority of the studies used the CS unplugged term when referring to “paper–pencil activities,” “problem solving,” “storytelling,” “games,” “tangible programming,” and even “robotics.”

关键词： Thermodynamics  

摘要： With the rapid development of quantum technology, one of the leading applications that has been identified is the simulation of chemistry. Interestingly, even before full scale quantum computers are available, quantum computer science has exhibited a remarkable string of results that directly impact what is possible in chemical simulation with any computer. Some of these results even impact our understanding of chemistry in the real world. In this perspective, we take the position that direct chemical simulation is best understood as a digital experiment. While on one hand this clarifies the power of quantum computers to extend our reach, it also shows us the limitations of taking such an approach too directly. Leveraging results that quantum computers cannot outpace the physical world, we build to the controversial stance that some chemical problems are best viewed as problems for which no algorithm can deliver their solution in general, known in computer science as undecidable problems. This has implications for the predictive power of thermodynamic models and topics like the ergodic hypothesis. However, we argue that this perspective is not defeatist, but rather helps shed light on the success of existing chemical models like transition state theory, molecular orbital theory, and thermodynamics as models that benefit from data. We contextualize recent results showing that data-augmented models are more powerful rote simulation. These results help us appreciate the success of traditional chemical theory and anticipate new models learned from experimental data. Not only can quantum computers provide data for such models, but they can extend the class and power of models that utilize data in fundamental ways. These discussions culminate in speculation on new ways for quantum computing and chemistry to interact and our perspective on the eventual roles of quantum computers in the future of chemistry. Copyright © 2021, The Authors. All rights reserved.

关键词： Information technology   Software   Lab life   Computer science  

摘要： Maintaining outdated PCs can be a matter of necessity - and a labour of *** Anna Nowogrodzki

关键词： Cryptography   Elliptic curve cryptography   Delays   Length measurement   Hardware   Computer science   Transforms  

摘要： Hardware realization of public-key cryptosystems often entails Montgomery modular multiplication (MMM), which is more efficient in residue number systems (RNS). A large pool of co-prime moduli allows for higher number of dynamically changeable moduli-set pairs for the required base extension, leading to ultra-wide key-lengths to accommodate the indispensable resistance to differential power-analysis (DPA) attacks. The moduli are often of the form ${2^r} - {{\delta }}$ , where $r$ denotes the width of residue channels. In a previous relevant RNS MMM design, with $r\ = \ 64$ , probability of a successful DPA attack is less than ${2^{ - 66}}$ , where efficient arithmetic is obtained only for a limited set of moduli that are insufficient for key-lengths over 1024 bits. Here we propose a free- ${{\delta }}$ RNS MMM scheme, for up-to 8192-bit key-lengths and fast 16-bit residue channels, based on the proposed ${{\delta }}$ -independent modulo-( ${2^r} - {{\delta }}$ ) adders and multipliers. Moreover, we propose an especial method for moduli selection that is required for base extension, leading to the same aforementioned DPA-resistance measure and much lower measures for key-lengths over 1024. The implementation results show $82,69,44\ percent$ less RSA delay, for key-lengths $512,1024,2048$ , respectively of the home designs versus the 512-bit main reference design, and more than $5,100\ percent$ for $4096,8192$ key-lengths, respectively, all per 512-bit encrypted messages.

关键词： Visualization   Rivers   Rendering (computer graphics)   Three-dimensional displays   Streaming media   Computer science   Shape   Flow visualization   stream surfaces   visual transformation   comparative visualization  

摘要： We present SurfRiver, a new visual transformation approach that flattens stream surfaces in 3D to rivers in 2D for comparative visualization. Leveraging the TextFlow-like visual metaphor, SurfRiver untangles the convoluted individual stream surfaces along the flow direction and maps them along the horizontal direction of the abstract river view. It stacks multiple surfaces along the vertical direction of the river view. This visual mapping makes it easy for users to track along the flow direction and align stream surfaces for comparative study. Through brushing and linking, the river view is connected to the spatial surface view for collective reasoning. SurfRiver can be used to examine a single stream surface, investigate seeding sensitivity or variability of a family of surfaces from a group of related seeding curves, or explore a collection of representative surfaces. We describe our optimization solution to achieve the desirable mapping, present SurfRiver interface and interactions, and report results from different flow fields to demonstrate its efficacy. Feedback from a domain expert also indicates the promise of SurfRiver.

关键词： 实践教学模式   校企合作   实践教学基地  

摘要： 针对计算机类专业人才培养中出现的一些具体问题,结合大连民族大学计算机科学与工程学院实践教学的实际情况,在学院“一头一尾两足双翼”人才培养模式指导下,构建“四年八学期一贯制”的实践教学体系,提出“5-8”校企深度合作实践教学模式,三年的实践表明,其对提高学生的实践创新能力和提升毕业生的就业质量效果显著。

关键词： Tensile stress   Big Data   Data analysis   History   Computer science   Tools   Matrix decomposition   Cyber-physical-social systems   big data   ubiquitous computing   tensor decomposition   tensor network   incremental tensor train decomposition   quantized tensor train  

摘要： Cyber-physical-social big data generated from ubiquitous devices and diverse spaces generally are multi-source, heterogeneous, and deeply intertwined. To efficiently analyze and handle the ubiquitous cyber-physical-social big data, tensor is considered as an effective tool, but the curse of dimensionality is still the main bottleneck of tensor-based big data analysis. Tensor networks can considerably alleviate or overcome it through the tensor approximate theory. Therefore, this paper focuses on developing an efficient big data processing framework based on tensor networks and providing an incremental tensor train decomposition approach for the streaming big data. Concretely, this paper first presents a hierarchical cyber-physical-social big data processing framework composed of three planes, namely, data representation and decomposition, data storage and processing, and data analysis and service, in which tensor train (TT) and quantized TT decompositions are particularly introduced to remarkably overcome the curse of dimensionality. Besides, to efficiently handle the continuous streaming big data and avoid the repeated decomposition for the history data, an incremental tensor train decomposition (ITTD) approach is proposed and the complexities are further analyzed in detail. Experimental results demonstrate that ITTD demonstrably outperforms the nonincremental TT decomposition in execution time on the precise of guaranteeing the nearly equal approximation error.

关键词： Layout   Memory management   Optimization   Acceleration   Space exploration   Computer science   Dictionaries   Database   conjunctive predicates   storage layout   CPU  

摘要： Database queries can contain multiple predicates. The optimization of conjunctive predicates is still vital to the overall performance of analytic data processing tasks. Prior work proposes several memory-efficient storage layouts, e.g., BitWeaving and ByteSlice, to significantly accelerate predicate evaluation, as circuit-level intra-cycle parallelism available in modern CPUs can be exploited such that the total number of instructions can be dramatically reduced. However, the performance potential of conjunctive predicates has not been harvested yet under such storage layouts as there is no accurate cost model to provide necessary insights that guide the optimization process. In this paper, we propose a hybrid empirical/analytical cost model (Understanding) to unveil the performance characteristics of such storage layouts when applying to predicate evaluation. Our cost model takes into account effect of non-linear factors, e.g., cache miss and branch misprediction, and easily applies to different CPUs. The main finding from our cost model is to distinguish high-cost instruction (which suffers from cache miss and/or branch misprediction) from low-cost instruction (which enjoys cache hit and correct branch prediction) in the context of predicate evaluation under these storage layouts. Guided by such a finding, we propose a simple execution scheme Hebe (Optimizing), which is order-oblivious while maintaining high performance. Hebe is attractive to the query optimizer (QO), as the QO does not need to go through a sampling process to decide the optimal evaluation order in advance. The intuition behind Hebe is to significantly reduce the number of high-cost instructions while keeping low-cost instructions unchanged. Our finding from Hebe sheds light on the importance of accurate cost model that guide us to derive an efficient execution scheme for query processing on modern CPUs.

关键词： 大数据时代   软件工程   计算机   开发  

摘要： 大数据信息技术应用背景下,充分掌握软件工程方法技术发展方向,并了解软件工程方法在计算机软件开发方面基础特征,可以充分提高软件工程技术应用技术能力,对解决软件工程方法在计算机软件开发方面面临技术问题起到辅助作用。

关键词： 新工科   产教融合   多学科交叉   改革  

摘要： “新工科”是基于国家战略发展新需求、国际竞争新形势、立德树人新要求而提出的工程教育改革方向。在这样的背景下,计算机科学与技术作为信息技术的核心之一,其专业改革势在必行。本文对计算机科学与技术专业,剖析人才培养方面存在的不足,从培养方案的制定、多学科交叉融合、产教融合等方面入手,更新教育理念,优化人才培养标准,为新工科背景下计算机科学与技术专业改革提供新思路。