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关键词： Economics   Vehicular ad hoc networks   Game theory   Games   Computer science   Throughput   Stability analysis   VANET   Incentive Mechanism   Behavioral Economics   Anchoring Effect  

摘要： Vehicular Ad-hoc NETwork (VANET) is a wireless self-organized network composed of vehicles and Road Side Units (RSUs) providing users services. There are problems such as difficulty in maintaining end-to-end links between vehicles and RSUs, and limited bandwidth and channel resources. Incentive mechanisms are necessary to attract a sufficient number of vehicles to participate in data forwarding and share resources efficiently among vehicles in order to solve the above problems. There are two decision-making stages for a node. In the initial stage, a new node that has never participated decides whether to participate;in the following stage, the participating nodes decide whether to participate again. The current incentive mechanisms are based on traditional economics, which have two problems: 1) the role of anchors (that is, reference points) is not considered in both decision-making stages;2) using the same utility function to evaluate two different decision-making stages which are actually affected by two different anchors. However, anchoring effect in behavioral economics has proved that people make decisions based on the experience of others (called Experimenter-Provided Anchoring, EPA) when they are first time to participate in data forwarding. They rely on their own experience (called Self-Generated Anchoring, SGA) when they already have forwarding experience. Therefore, the users' decision-making in the existing incentive mechanisms deviates from reality. Based on anchoring effect, we propose a Dual-Process Mechanism (DPM), which includes the user Attraction mechanism based on Experimenter-Provided Anchoring (AEPA) and the user Continuous Working mechanism based on Self-Generated Anchoring (CWSGA). AEPA is used to motivate those new nodes to participate in data forwarding. CWSGA is used to motivate those nodes which have participated to forward data again. Simulations show that DPM has a 10% increase in cooperation rate compared with the currently most used in

关键词： Science education   Complex systems   Computer models   Multiple representations   Physical laboratories  

摘要： How do different components of a learning environment contribute to learning in science? The study examines the contribution of laboratory experiments and computer model explorations to the learning of chemistry through a complex-systems approach. Specifically, junior high-school students' learning of chemistry via four different methods were compared: with computer models using a complexity approach (MC);with laboratory experiments using a complexity approach (LC);with computer models and laboratory experiments using a complexity approach (MLC);and with a normative disciplinary approach that included only laboratory experiments (LN). Learning was tracked for the relevant science concepts, such as pressure, and for system component ideas, such as emergence. One hundred and fifty-nine seventh-grade students participated in a non-randomized four-group comparison quasi-experimental pre-test-intervention-post-test design with identical pre- and post-tests spaced 2-3 weeks apart. The learning activities for all modes were twelve 45-min lessons. Students' scores rose in all four groups, but to a different extent, showing a distinct and strong advantage to combining models and labs (MLC), while no differences were seen between the MC and LC conditions. There was also an advantage to learning with the complexity approach (LC) compared to learning using the normative approach (LN). More importantly, the specific concepts that were learned show distinct patterns, distinguishing the contributions of each learning environment component. These research findings have both practical implications when designing learning environments and theoretical contributions to understanding the necessary role of different experiences in learning science.

关键词： Fuzzy sets   Gravity   1   f noise   Computer science   Uncertainty   Computational complexity   Center of gravity (COG)   defuzzification   interval type-2 fuzzy set (IT2FS)   Nie-Tan defuzzifier   polygonal fuzzy set  

摘要： Defuzzification plays an important role in the applications of interval type-2 fuzzy sets (IT2FSs). However, computational complexity of existing defuzzification methods has turned this procedure into an important bottleneck toward the use of IT2FSs. It has been proved that the Nie-Tan method is an accurate discretizing-based method for calculating the center of gravity (COG) of IT2FSs. In this article, we propose a fast and accurate method for calculating the COG-Nie-Tan defuzzification-of polygonal IT2FSs on discrete and continuous domains without the need of discretization. The proposed method calculates the accurate COG for trapezoidal and triangular IT2FSs as special cases of polygonal IT2FSs. Moreover, any IT2FS can be approximated by a polygonal IT2FS-the higher the order of polygonal IT2FS, the better the approximation. Hence, using the proposed method on an IT2FS that is approximated by an appropriate polygonal IT2FS results in a more accurate COG.

关键词： Information technology   Computer science   Australia  

摘要： In the above article [1] , the corresponding author was incorrectly identified. The corresponding author is the first author, S. Nithya.

关键词： Computer science   Engineering  

摘要： A machine-learning system has been trained to place memory blocks in microchip designs. The system beats human experts at the task, and offers the promise of better, more-rapidly produced chip designs than are currently possible.

关键词： Teacher support   Small group collaboration   Science inquiry   Technology   Affect   Social network analysis  

摘要： Technology-enhanced collaborative inquiry learning has gained a firm position in curricula across disciplines and educational settings and has become particularly pervasive in science classrooms. However, understanding of the teacher's role in this context is limited. This study addresses the real-time shifts in focus and distribution of teachers' guidance and support of different student groups during in-person computer-supported collaborative inquiry learning in science classrooms. Teachers' self-perceptions of their guidance and affect were supplemented with students' self-reported affect. A mixed-methods approach using video analyses and questionnaire data revealed differences between teacher guidance and support associated with teacher perceptions and group outcomes. Groups' prior science competence was not found to have an effect on teacher guidance and support, rather the teachers guided the groups they perceived as motivated and willing to collaborate. Teacher affect was compounded by student affect, suggesting that consideration of the reciprocal perceptions of teachers and students is necessary in order to understand the teachers' role in collaborative learning.

关键词： BAME women   Bullying   gender   harassment   police   race  

摘要： This article examines the hidden and under-researched area of bullying and harassment of Black and Asian Minority Ethnic (BAME) women in the police service in England. It discusses the impact of a historical policy failure to acknowledge the importance of intersectionality in matters of diversity and the continuing struggle between race and gender. This contributes to the ‘invisibility and sexualization’ of BAME women in policing. In doing so, it makes BAME women susceptible to unique tactics of bullying and harassment that contribute to their impeded progression compared with their White counterparts. These unique tactics are enhanced by the police organization and enforced by police culture. The article concludes that the bullying and harassment of BAME women are underpinned by issues of patriarchy and racism that are difficult to challenge in a bureaucratic and hierarchical organization like the police. © The Author(s) 2021.

关键词： Data models   Contracts   Computer science   Safety   Reliability   IoV   trust management   smart contract   ethereum   blockchain  

摘要： In the Internet of Vehicles (IoV), vehicles communicate wirelessly with other vehicles, sensors, pedestrians, and roadside units. IoV is aimed at improving road safety, driving comfort, and traffic efficiency. However, IoV is exposed to a range of threats to security and privacy. The presence of dishonest and misbehaving peers in the system is of a major concern, which may put lives in danger. Thus, establishing trust among these probable untrusted vehicles is one of the most significant challenges of such a network. The critical pitfalls of existing and traditional mechanisms are scalability, a single point of failure, maintaining the quality of service, verification, and revocation and dealing with sparsity, consistency, availability, efficiency, robustness, privacy concerns are some of the biggest challenges to be addressed. Blockchain technology, with its great success in applications like cryptocurrencies and smart contracts, is considered as one of the potential candidates to build trust in IoV. In this paper, we propose a blockchain-based decentralized trust management scheme using smart contracts. Specifically, we introduce the concept of blockchain sharding for reducing the load on the main blockchain and increasing the transaction throughput. Our proposal has two key contributions: blockchain to maintain and update reliable and consistent trust values across the network and incentive scheme to encourage peers to perform well. We also conduct extensive experiments, which demonstrate the implementation feasibility of proposed mechanisms in the real world.

关键词： Pair programming   collaborative learning   college students   experimental design  

摘要： Active and collaborative learning has shown considerable promise for improving student outcomes and reducing group disparities. As one common form of collaborative learning, pair programming is an adapted work practice implemented widely in higher education computing programs. In the classroom setting, it typically involves two computer science students working together on the same programming assignment. The present study examined a cluster-randomized trial of 1,198 undergraduates in 96 lab sections. Overall, pair programming had no significant effect on students' course performance;subject matter interest;plans for future coursework;or their confidence, comfort, and anxiety with computer science. These findings were consistent across various student characteristics, except that students with favorable pretest scores exhibited negative effects from pair programming.