The safety applications for cooperative driving in VANETs, typically require the dissemination of safety-related information to all vehicles with high reliability and a strict timeline. However, due to the high vehicle mobility, dynamic traffic density, and a self-organized network, Safety message dissemination has a special challenge to efficiently use the limited network resources to satisfy its requirements. With this motivation, we propose a novel broadcasting protocol referred to as congestion awareness multi-hop broadcasting (CAMB) based loosely on a TDMA-like transmission scheduling scheme. The proposed protocol was evaluated using different traffic scenarios within both a realistic channel model and an 802.11p PHY/MAC model in our simulation. The simulation results showed that the performance of our CAMB protocol was better than those of the existing broadcasting protocols in terms of channel access delay, packet delivery ratio, end-to-end delay, and network overhead.

A mobile ad-hoc network (MANET) consists of a collection of wireless mobile nodes without any fixed network infrastructure. Since the mobile nodes form a constantly changing topology, the design of efficient and scalable routing protocols is a fundamental challenge in MANETs. In the current literature, position-based routing protocols are regarded as having better scalability and lower control overhead than topology-based routing protocols. Since location services are the most critical part of position-based routing protocols, we present a multi-home-region scheme, Distributed Virtual Home Region with Spatial Awareness (DVHR-SA), to improve the performance of location service in this paper. Our scheme adaptively selects different update and query procedures according to the location of a source node. The simulation results show that DVHR-SA shortens the lengths of the update, query and reply paths. Our scheme also reduces the overall network message overhead. Therefore, DVHR-SA is considerably fast and stable.

The AODV routing protocol, which is simple and efficient, is often used in wireless sensor networks to transmit data. The AODV routing protocol constructs a path from the source node, which detects the target, to the sink node. Whenever the target moves, the path will be reconstructed and the RREQ packet will be broadcasted to flood the wireless sensor network. The localization repair routing protocol sets up a reconstruction area and restricts the broadcast of the RREQ packet to that area to avoid broadcast storm. However, this method cannot reconstruct the path once the target moves out of the reconstruction area. In this paper, we propose a lightweight routing protocol for mobile target detection. When the path breaks because of the movement of the target, the nodes can repair the path effectively using the presented routing information to achieve the lightweight effect.

Multi-hop wireless ad hoc networks suffer from temporary link error due to fading. In order to improve packet transmission reliability and achieve efficient transmission in fading environment, a new cognitive temporary bypassing scheme is proposed based on a cross-layer approach and cognitive behavior of local nodes. The proposed scheme enables neighboring nodes to prepare and create a temporary bypass for lost-packets. This is done by monitoring message packets that include information of the multi-hop route and link-acknowledgement. The scheme also includes an anti-collision function that is necessary to prevent contention among multiple bypassing nodes. Packet success probability with the proposed scheme is studied both by theoretical analysis and time-domain computer simulation for Rayleigh faded single- and multi-hop links. Network simulation using a modified QualNet simulator validate that packet success probability is remarkably improved with the scheme for maximum Doppler frequencies up to 30 Hz.

In 2009, Jeong et al. proposed a secure binding encryption scheme and an efficient secret broadcast scheme. This paper points out that the schemes have some errors and cannot operate correctly, contrary to their claims. In addition, this paper also proposes improvements of Jeong et al.'s scheme that can withstand the proposed attacks.

The patching technique has been used for reducing initial waiting time in VOD services. Traditionally the technique has been applied to fixed segment NVOD scheduling. However, variable segment NVOD scheduling is known to have a better server bandwidth and less initial waiting time. In this paper, we propose a new scheduling algorithm for a true VOD service by incorporating the patching technique into variable segment NVOD scheduling. Our algorithm provides jitter-free playback while minimizing the use of the patching bandwidth. We present the proof of the correctness of our algorithm.

Due to the increase of operation frequency in recent LSI systems, signal propagation delays are required to achieve specifications with very high accuracy. In order to achieve the severe requirements, signal propagation delay is taken into account in the routing design of PCB (Printed Circuit Board). In the routing design of PCB, the controllability of wire length is often focused on since it enables us to control the routing delay. In this paper, we propose CAFE router which obtains routes of multiple nets with target wire lengths for single layer routing grid with obstacles. CAFE router extends the route of each net from a terminal to the other terminal greedily so that the wire length of the net approaches its target wire length. Experiments show that CAFE router obtains the routes of nets with small length error in short time.

Clock gating is the insertion of control signal for registers to switch off unnecessary clock signals selectively without violating the functional correctness of the original design so as to reduce the dynamic power consumption. Commercial EDA tools usually have a mechanism to generate clock gating logic based on the structural method where the control signals specified by designers are used, and the effectiveness of the clock gating depends on the specified control signals. In the research, we focus on the automatic clock gating logic generation and propose a method based on the candidate extraction and control signal selection. We formalize the control signal selection using linear formulae and devise an optimization method based on BDD. The method is effective for circuits with a lot of shared candidates by different registers. The method is applied to counter circuits to check the co-relation with power simulation results and a set of benchmark circuits. 19.1-71.9% power reduction has been found on counter circuitsafter layout and 2.3-18.0% cost reduction on benchmark circuits.

While volunteer computing (VC) systems reach the most powerful computing platforms, they still have the problem of guaranteeing computational correctness, due to the inherent unreliability of volunteer participants. Spot-checking technique, which checks each participant by allocating spotter jobs, is a promising approach to the validation of computation results. The current spot-checking is based on the implicit assumption that participants never distinguish spotter jobs from normal ones; however generating such spotter jobs is still an open problem. Hence, in the real VC environment where the implicit assumption does not always hold, spot-checking-based methods such as well-known credibility-based voting become almost impossible to guarantee the computational correctness. In this paper, we generalize spot-checking by introducing the idea of imperfect checking. This generalization allows to guarantee the computational correctness under the situation that spot-checking is not fully-reliable and participants may distinguish spotter jobs. Moreover, we develop a generalized formula of the credibility, which enables credibility-based voting to utilize check-by-voting technique. Simulation results show that check-by-voting improves the performance of credibility-based voting, while guaranteeing the same level of computational correctness.

This paper presents a method of expanding the operating frequency band of a Reverberating TEM Cell (RTC) for electromagnetic compatibility (EMC) testing. To expand the operating frequency band of an RTC, this paper places a wire septum inside the cell instead of a solid septum. The maximum usable frequency (MUF) for TEM cell operation and the lowest usable frequency (LUF) for reverberating chamber operation with the wire septum are studied and compared with a conventional solid septum. The E field strengths inside the RTC are measured and evaluated. The measurement results show that the RTC with the wire septum have similar MUF to the RTC with a solid septum at TEM mode, but have much lower LUF at a reverberating mode, which proves that the operating frequency band of the RTC can be expanded by using the wire septum.

In this letter, we first study the impact of the basic reference frame jitter on the digital image stabilization. Next, a method for stabilizing the digital image sequence based on the correction for basic reference frame jitter is proposed. The experimental results show that our proposed method can effectively decrease the excessive undefined areas in the stable image sequence resulting from the basic reference frame jitter.

In this letter, we present a flow-aware opportunistic routing protocol over wireless mesh networks. Firstly, a forwarder set selection mechanism is proposed to avoid potential flow contention, thus alleviating possible congestion from the increased number of flows. Secondly, a Round-Robin packet sending fashion combined with batch-by-batch acknowledgement is introduced to provide reliability and improve throughput. Evaluations show that our protocol significantly outperforms a seminal opportunistic routing protocol, MORE, under both single and multiple flow scenarios.

This paper proposes a GPU-based method that can visualize voxelized surface data with fine and complicated features, has high rendering quality at interactive frame rates, and provides low memory consumption. The surface data is compressed using run-length encoding (RLE) for each level of detail (LOD). Then, the loop for the rendering process is performed on the GPU for the position of the viewpoint at each time instant. The scene is raycasted in planes, where each plane is perpendicular to the horizontal plane in the world coordinate system and passes through the viewpoint. For each plane, one ray is cast to rasterize all RLE elements intersecting this plane, starting from the viewpoint and ranging up to the maximum view distance. This rasterization process projects each RLE element passing the occlusion test onto the screen at a LOD that decreases with the distance of the RLE element from the viewpoint. Finally, the smoothing of voxels in screen space and full screen anti-aliasing is performed. To provide lighting calculations without storing the normal vector inside the RLE data structure, our algorithm recovers the normal vectors from the rendered scene's depth buffer. After the viewpoint changes, the same process is re-executed for the new viewpoint. Experiments using different scenes have shown that the proposed algorithm is faster than the equivalent CPU implementation and other related methods. Our experiments further prove that this method is memory efficient and achieves high quality results.

In this letter, we propose a revised geographic routing protocol and a scheduling algorithm to support real-time applications, which are often observed in wireless sensor networks. In order to meet real-time requirement, a specific application is modeled as an (m,k)-firm stream that has a property of weakly hard real-time system. In addition, both a priority-based scheduling and a geographic forwarding scheme based on delay, distance, and remaining slack time are newly proposed. Simulations and their analysis are followed to validate the suitability of reduced dynamic failure probability and extended network lifetime.

The unification problem for term rewriting systems (TRSs) is the problem of deciding, for a TRS R and two terms s and t, whether s and t are unifiable modulo R. We have shown that the problem is decidable for confluent simple TRSs. Here, a simple TRS means one where the right-hand side of every rewrite rule is a ground term or a variable. In this paper, we extend this result and show that the unification problem for confluent semi-constructor TRSs is decidable. Here, a semi-constructor TRS means one where all defined symbols appearing in the right-hand side of each rewrite rule occur only in its ground subterms.

A stacked rectangular microstrip antenna with a shorting plate and a helical pin is proposed as a car antenna for triple band operation in ITS. The proposed antenna operates as a conventional stacked microstrip antenna at the highest frequency band. At the middle and the lowest frequency bands, the antenna radiates at low elevation angles from the helical pin and the shorting plate. In this paper, as an example of triple band antennas in the ITS, an antenna is designed that supports PHS, VICS and ETC. The proposed antennas have the proper radiation pattern for each application and are small in size.

The software reliability is the ability of the software to perform its required function under stated conditions for a stated period of time. In this paper, a hybrid methodology that combines both ARIMA and fractal models is proposed to take advantage of unique strength of ARIMA and fractal in linear and nonlinear modeling. Based on the experiments performed on the software reliability data obtained from literatures, it is observed that our method is effective through comparison with other methods and a new idea for the research of the software failure mechanism is presented.

A new type of digital filter for removing impulsive noise in color images is proposed using interactive evolutionary computing. This filter is realized as a rule-based system containing switching median filters. This filter detects impulsive noise in color images with rules and applies switching median filters only at the noisy pixel. Interactive evolutionary computing (IEC) is adopted to optimize the filter parameters, considering the subjective assessment by human vision. In order to detect impulsive noise precisely, complicated rules with multiple parameters are required. Here, the relationship between color components and the degree of peculiarity of the pixel value are utilized in the rules. Usually, optimization of such a complicated rule-based system is difficult, but IEC enables such optimization easily. Moreover, human taste and subjective sense are highly considered in the filter performance. Computer simulations are shown for noisy images to verify its high performance.

Slow development in battery technology and rapid advances in ultra-capacitor design have motivated us to investigate the possibility of using capacitors as the sole energy storage for wireless sensor nodes to support ubiquitous computing. The starting point of this work is TwinStar, which uses ultra-capacitor as the only energy storage unit. To efficiently use the harvested energy, we design and implement feedback control techniques to match the activity of sensor nodes with the dynamic energy supply from environments. We conduct system evaluation by deploying sensor devices under three typical real-world settings -- indoor, outdoor, and mobile backpack under a wide range of system settings. Results indicate our feedback control can effectively utilize energy and ensure system sustainability. Nodes running feedback control have longer operational time than the ones running non-feedback control.

Inspired from natural self-managing behavior of the human body, autonomic systems promise to inject self-managing behavior in software systems. Such behavior enables self-configuration, self-healing, self-optimization and self-protection capabilities in software systems. Self-configuration is required in systems where efficiency is the key issue, such as real time execution environments. To solve self-configuration problems in autonomic systems, the use of various problem-solving techniques has been reported in the literature including case-based reasoning. The case-based reasoning approach exploits past experience that can be helpful in achieving autonomic capabilities. The learning process improves as more experience is added in the case-base in the form of cases. This results in a larger case-base. A larger case-base reduces the efficiency in terms of computational cost. To overcome this efficiency problem, this paper suggests to cluster the case-base, subsequent to find the solution of the reported problem. This approach reduces the search complexity by confining a new case to a relevant cluster in the case-base. Clustering the case-base is a one-time process and does not need to be repeated regularly. The proposed approach presented in this paper has been outlined in the form of a new clustered CBR framework. The proposed framework has been evaluated on a simulation of Autonomic Forest Fire Application (AFFA). This paper presents an outline of the simulated AFFA and results on three different clustering algorithms for clustering the case-base in the proposed framework. The comparison of performance of the conventional CBR approach and clustered CBR approach has been presented in terms of their Accuracy, Recall and Precision (ARP) and computational efficiency.