Project-based learning is among the most common learning approaches aimed at conveying professional standards and best practices to students in programming courses. However, team projects commonly impose problems related to responsibility sharing, such as low effort or inequality in contributions. This paper presents a collaborative programming assessment system featuring a code quality assessment function with specific metrics to measure individual contributions. Student engagement data is used to detect nonconformities in collaboration using a learning analytical approach. Latent profile analysis was used to detect four theoretical team profiles differentiated by team effort (2 levels) and within-team collaboration (2 levels). We demonstrated the efficacy of assessing code to evaluate team dynamics and student behaviour, wherein efforts to resolve coding style failures can be used as a proxy by which to estimate the taskwork awareness of team members. Submission data from 146 students in 41 web-programming projects revealed four behavioural patterns that could potentially hinder the effective functioning of programming teams: free-riding, social loafing, the bystander effect, and lone wolves. We also demonstrated the applicability of automated programming assessment systems to the monitoring of learning progress, thereby facilitating timely interventions to correct difficulties at the team level.

Summary Pedestrian detection is essential for improving pedestrian safety in an intelligent traffic system. The efficiency of the system is affected by real‐time processing and the error rate of detection. These concerns have not been completely addressed in previous studies. Therefore, this study proposes a real‐time pedestrian recognition system that ensures high accuracy by using a deep learning classifier and zebra‐crossing recognition techniques. The proposed system was designed to improve pedestrian safety and reduce accidents at intersections. Environmental feature vectors were first used to detect zebra crossings and to determine crossing areas. An adaptive mapping technique was then used to map the pedestrian waiting area based on the crossing area. A dual camera mechanism was used to maintain detection accuracy and improve system fault tolerance. Finally, the you‐only‐look‐once model was used to recognize pedestrians at intersections. A system prototype was implemented to verify the feasibility of the proposed system. The results revealed that the proposed scheme outperforms the conventional histogram of oriented gradients and Haarcascade schemes.

Existing intelligent transport systems (ITS) do not fully consider and resolve accuracy, instantaneity, and compatibility challenges while resolving traffic congestion in Internet of Vehicles (IoV) environments. This paper proposes a traffic congestion monitoring system, which includes data collection, segmented structure establishment, traffic‐flow modelling, local segment traffic congestion prediction, and origin‐destination traffic congestion service for drivers. Macroscopic model‐based traffic‐flow factors were formalized on the basis of the analysis results. Fuzzy rules‐based local segment traffic congestion prediction was performed to determine the traffic congestion state. To enhance prediction efficiency, this paper presents a verification process for minimizing false predictions which is based on the Rankine‐Hugoniot condition and an origin‐destination traffic congestion service is also provided. To verify the feasibility of the proposed system, a prototype was implemented. The experimental results demonstrate that the proposed scheme can effectively monitor traffic congestion in terms of accuracy and system response time.

Taxis have a vital role in the transportation system and Internet of Vehicles (IoV) techniques can be used to improve the fuel and time efficiencies of taxis. However, the existing work does not address the traffic congestion that may occur when a large amount of taxis gathers in certain queuing areas. This paper proposes an adaptive and hotspot-aware taxi zone queuing system to deal with the problem while still guarantees the fuel and time efficiencies. The adaptive scheme features data collection, hotspot extraction, an adaptive zone queuing protocol, and navigation services for taxi drivers. Real data were collected from Taiwan Taxi Inc., the largest taxi company in Taiwan. Queuing zone hotspots were identified through the analysis of the collected data. The hotspots represented. A navigation service was based on the proposed protocol. To verify the feasibility of the proposed system, a prototype was implemented. The experimental results demonstrated that the proposed scheme outperformed other schemes in reducing waiting time and the average number of taxis.

Abstract In most studies of wireless sensor networks (WSNs), sensor nodes and sinks are typically stationary. However, mobile sinks are required in various applications of real‐life environments, and delivering sensed data to mobile sinks using ordinary routing protocols is very inefficient. Multicasting is an important process in the minimization of the number of transmissions in WSNs. Since sensor nodes have limited resources, many studies have focused on how to send data to specific receivers efficiently. This work presents a grid‐based hierarchical multicast (HM) routing protocol for WSNs with mobile sinks. Location servers (LSs) are adopted to manage the information about the locations of receivers and then a multicast tree is constructed distributively to reduce the update cost and energy consumed by sink mobility. The multicast tree can be shared by multiple sources, reducing the path construction overhead. Furthermore, effective maintenance mechanisms that make the multicast tree more stable and robust are presented. Finally, the performance of the proposed HM is investigated by simulation. Simulation results demonstrate that the proposed protocol has a lower energy consumption and higher multicast efficiency than distributed multicast routing protocol (DMRP) and hierarchical geographic multicast routing (HGMR), especially when many sources and receivers are involved. Copyright © 2010 John Wiley & Sons, Ltd.

Many cities have established Web-based road hazard report/notification systems to improve citizen's driving safety and comfort. However, some of the systems are not very user-friendly. On the other hand, a driver sometimes does not know his/her vehicle already has some problems, but the malfunctioning vehicle is still driven on the road. Under this condition, the driver and other road users are all not very safe. This paper proposes a DSRC vehicular warning and notification system. The proposed system consists of multiple communication interfaces to provide real-time traffic warning and rapid notification of traffic information. It is capable of detecting road hazards and transmitting traffic information to the Internet through intervehicular communications via DSRC. In addition, the vehicular status self-check data can be acquired through Control Area Network (CAN) bus. With Web Services, the proposed system could report traffic information to city traffic centers for informing other road users, or car maintenance factories for car fault rescue. A prototype system was implemented, and the road test results show the proposed system can be used not only to enhance driving safety but also to simplify the notification of road problems.

Wireless Mesh Networks (WMNs) has been attracted significant attention due to achieve a wide-area wireless environment with flexible-configuration and low-cost properties. When WMNs is used as an infrastructure for Internet access, all network traffic from mesh routers will be forwarded to the gateways that are directly connected to the wired network. Communication in large-scale wireless networks may suffer capacity bottlenecks in the gateway and local congestions among the mesh routers. Therefore, in this paper, we proposed a hybrid strategy which combines the gateway-based and path-based traffic control schemes. In order to obtain simple and efficient results, the k-level congestion awareness scheme is proposed which uses the fuzzy logic technique to estimate the gateway loading. The border nodes (BNs) will redirect partial traffic to adjacent regions that belong to neighbor gateways if congestion occurs. Therefore, the proposed scheme can adjust the network traffic automatically according to traffic condition that can smoothly and immediately share traffic load to neighbor gateways. The validity of the model has been demonstrated through simulation experiments. Our simulation results have also indicated that our scheme is a good choice for WMNs to support efficient congestion control, especially in bursty traffic environments.

Abstract Anycast is a one‐to‐any bidirectional transmission scheme that can be used to provide various service‐oriented applications. However, traditional anycast cannot support some distributed applications that need to locate multiple servers such as network time protocols and threshold cryptography. Although there are some extended anycast schemes that can support the discovery ofkservices, they may cause high control overhead, low satisfaction ratio, or high searching latency when there are more service requesters and providers. The main reasons for these shortcomings are unknown service information and limited hierarchical structure. This work proposes an efficient anycast scheme, called AnyKast, for discoveringkservices in cluster‐based mobilead hocnetworks. In the AnyKast scheme, an anycast tree based on the clustering and virtual backbone is established to reduce unnecessary message transmission. In the anycast tree, anycast clusterheads disseminate their information to certain specific nodes that take the service information and perform the service selection task instead of blindly searching. Furthermore, to decrease the cost of service information collection and maintenance, scope flooding is used to limit the information transmission, and information piggybacking and periodical inquiry mechanism are used to increase the service information accuracy. The experimental results demonstrate that our scheme can effectively discover services, reduce request and reply message control overhead, and lower the searching latency. Copyright © 2010 John Wiley & Sons, Ltd.

Due to recent development in wireless communication networks, researches in Vehicular Ad-hoc Networks (VANETs) have been getting much attention on information sharing and service discovery. However, due to the ever-shifting mobility of vehicle topology, vehicles moving in non-fixed routes may not find suitable next-hop vehicles to pass the data. This paper proposes schemes to effectively circulate and discover service information with the aid of public transportation systems. Bus routes can be used to create a backbone structure and data can be posted and circulated on the structure to avoid the broadcast storm problem. Moreover, by adopting the proposed architecture, the required data can be effectively disseminated and discovered through the traffic infrastructure and mobile vehicles. The experiment results demonstrate that our scheme outperforms other schemes in terms of packet delivery ratio and end-to-end delay. Moreover, the overhead of our scheme outperforms other scheme with an increasing of number of service requests.

Wireless sensor networks consist of a large number of low-power, small-scale sensors with limited processing and communication capabilities. Such networks are usually applied to gather data from interested area or specific environment and deliver to remote users for analyzing or monitoring. Because of sensing devices are usually powered by batteries, it is a great challenge to meet the performance of long system lifetime required by different applications under limited power. In the densely deployed sensor networks, the area or data sensed by neighboring sensors may overlap. In recent researches, coverage preserved node scheduling has been proposed to conserve power and provide sensing reliability. By selecting appropriate sensors into sleep state, the system lifetime can be extended without losing coverage. In this paper, we propose a duster-based coverage-preserved node scheduling scheme. We divide sensors into clusters and group cluster members into sponsor sets based on neighbor information. The proposed approach distributes the workloads among sponsor set nodes and ensures sufficient coverage as long as possible

This work investigates and analyzes recent research trends and presents experimental guidelines on MANETs. More than 1,300 MANET related papers in IEEE/IEE Electronic Library (IEL Online) from 1998 to 2003 were collected and surveyed. The research trends, qualitative analysis and simulation guidelines from fifteen major MANET issues are investigated to assist the user in conducting MANET research. Based on recent six year trends we found that some issues such as routing and power management attracted much attention. We also found that some issues have potential study value, such as IP addressing and fault tolerance. In the qualitative analysis, we found that some factors such as scalability, stability, and reliability attracted much attention in major MANET issues. The essential simulation metrics for various MANET issues are identified and listed for experimental guidelines. The analysis results demonstrate the utilization trends for various MANET simulators.

When searching for resources on networks, the system often depends on the broadcast or multicast mechanism to acquire the information, which usually results in large overhead. It is a serious problem in ad-hoc wireless networks, where the bandwidth is limited and each node moves arbitrarily and acts not only as a host but also as a router. This work proposes an efficient anycasting scheme in ad-hoc wireless networks. The scheme can be used to reduce the request messages, decrease the overhead of response received from duplicate packets, and balance the load of ad-hoc wireless networks. Furthermore, our scheme can support any K services and attain the backup or fault tolerance purpose.

With higher requirement for communications and tremendous growth of mobile subscribers, maximizing bandwidth utilization in cell overlapping systems has been attracting much attention. This work develops an efficient channel allocation scheme based on the cell order and channel order to improve the channel capacity in an overlapping cellular system. Experimental results demonstrate that the channel selection order from picocells to macrocells outperforms other schemes in terms of call blocking rate, primary channel utilization rate, and assignment latency. Besides, in order to improve the performance of channel allocation, it is preferred to allocate more channels to smaller cells under a fixed channel capacity in an overlapping system. Furthermore, experimental results demonstrate that the call blocking rate decreases with the increasing of the utilization rate of primary channels.

In many scientific applications, array redistribution is usually required to enhance data locality and reduce remote memory access in many parallel programs on distributed memory multicomputers. Since the redistribution is performed at runtime, there is a performance trade-off between the efficiency of the new data decomposition for a subsequent phase of an algorithm and the cost of redistributing data among processors. In this paper, we present a generalized processor mapping technique to minimize the amount of data exchange for BLOCK-CYCLIC(kr) to BLOCK-CYCLIC(r) array redistribution and vice versa. The main idea of the generalized processor mapping technique is first to develop mapping functions for computing a new rank of each destination processor. Based on the mapping functions, a new logical sequence of destination processors can be derived. The new logical processor sequence is then used to minimize the amount of data exchange in a redistribution. The generalized processor mapping technique can handle array redistribution with arbitrary source and destination processor sets and can be applied to multidimensional array redistribution. We present a theoretical model to analyze the performance improvement of the generalized processor mapping technique. To evaluate the performance of the proposed technique, we have implemented the generalized processor mapping technique on an IBM SP2 parallel machine. The experimental results show that the generalized processor mapping technique can provide performance improvement over a wide range of redistribution problems.

Although the application of code transformations is critical to exploit parallelism in program code, few guidelines or tools are provided to determine what transformations should be applied and where they should be applied. In this paper, we approach this problem by first providing a taxonomy of code transformations to assist the user in parallelizing programs. We then present an efficient technique to remove transformations from the code when it is determined that they are ineffective or prevent more beneficial transformations from being applied. The technique to remove transformations employs inverse primitive actions, making it transformation independent. The technique uses the program dependence graph as the intermediate representation, making it language independent.

A transformation applied to optimize or parallelize a program may be found to be ineffective, or may be made invalid by code changes. In this paper, we present a technique to remove such transformations. The order of undoing the transformations is independent of the application order. The technique uses post conditions of a transformation to determine whether the transformation can be immediately removed. Transformations that affect the immediate removal of a transformation must be identified and removed. Other transformations made invalid by the removal of a transformation must also be undone. The technique employs inverse primitive actions, making the technique transformation independent. The enabling and disabling interactions of transformations are used to drive the process, thereby reducing redundant analysis when undoing transformations.

A software environment for visualization when parallelizing programs is described. The system supports multiparadigm program visualization, automatic generation of optimizers from specifications, interactive and undo facilities for code transformations, and a multilevel browser. Textual and graphical forms of optimization specification languages are utilized in the specification of both traditional and parallelizing transformations. An undo facility is provided for the user to remove ineffective or inappropriate transformations. An extended form of the program dependence graph is developed that not only enables the exploitation of parallelism in sequential programs by applying transformations but also facilitates mappings for code visualization. The conceptual framework that allows multiparadigm program visualization is presented. A multilevel browser can be used to browse any block of statements in one program view, and the corresponding code of another program view is highlighted.>