The IEEE has recently released IEEE 802.15.5 standard [3] to provide multi-hop mesh functions for low-rate wireless personal area networks (WPANs). In this paper, we extensively describe a link-layer reliable broadcast protocol referred to as timer-based reliable broadcast (TRB) [3] in the IEEE 802.15.5 standard. The TRB scheme exploits (1) bitmap based implicit ACK to effectively reduce the unnecessary error control messages and (2) randomized timer for ACK transmission to substantially reduce the possibility of contentions. Performance evaluation shows that the TRB scheme achieves 100% reliability compared with other schemes with expense of slightly increased energy consumption.

This paper presents a self-clustering algorithm to detect symmetry in images. We combine correlations of orientations, scales and descriptors as a triple feature vector to evaluate each feature pair while low confidence pairs are regarded as outliers and removed. Additionally, all confident pairs are preserved to extract potential symmetries since one feature point may be shared by different pairs. Further, each feature pair forms one cluster and is merged and split iteratively based on the continuity in the Cartesian and concentration in the polar coordinates. Pseudo symmetric axes and outlier midpoints are eliminated during the process. Experiments demonstrate the robustness and accuracy of our algorithm visually and quantitatively.

At the stage of software debugging, the effective interaction between software debugging engineers and fault localization techniques can greatly improve fault localization performance. However, most fault localization approaches usually ignore this interaction and merely utilize the information from testing. Due to different goals of testing and fault localization, the lack of interaction may lead to the issue of information inadequacy, which can substantially degrade fault localization performance. In addition, human work is costly and error-prone. It is vital to study and simulate the pattern of debugging engineers as they apply their knowledge and experience to this interaction to promote fault localization effectiveness and reduce their workload. Thus this paper proposes an effective fault localization approach to simulate this interaction via feedback. Based on results obtained from fault localization techniques, this approach utilizes test data generation techniques to automatically produce feedback for interacting with these fault localization techniques, and then iterate this process to improve fault localization performance until a specific stopping condition is satisfied. Experiments on two standard benchmarks demonstrate the significant improvement of our approach over a promising fault localization technique, namely the spectrum-based fault localization technique.

A folded monopole antenna fed by a CPW-to-trident transition feeder for compact wireless USB dongle devices is proposed. The antenna's dimensions are 1644.83.5 mm3, so it is suitable for low-profile wireless USB dongles. The proposed, compact monopole antenna resonates from 2.28 GHz to 10.8 GHz; hence, it can cover all wireless bands including WiBro (2.3–2.4 GHz), Bluetooth (2.4–2.484 GHz), WiMAX (2.5–2.7 GHz and 3.4–3.6 GHz), satellite DMB (2.605–2.655 GHz), 802.11b/g/a WLAN (2.4–2.485 GHz and 5.15–5.825 GHz), and UWB (3.1–10.6 GHz). A fabricated antenna is tested on a laptop to investigate the effects of the keypad and LCD screen on the resonant frequency and radiation pattern. The measured average gain of the fabricated antenna ranges from -2.76 dBi to 0.72 dBi.

This paper customizes Goal/Question/Metric (GQM) project monitoring models for various projects and organizations to take advantage of the data from the software tool EPM and to allow the tailoring of the interpretation models based upon the context and success criteria for each project and organization. The basic idea is to build less concrete models that do not include explicit baseline values to interpret metrics values. Instead, we add hypothesis and interpretation layers to the models to help people of different projects make decisions in their own context. We applied the models to two industrial projects, and found that our less concrete models could successfully identify typical problems in software projects.

During a software development phase where a product is progressively elaborated, it is difficult to guarantee that the refined product retains its original behaviors. In this paper, we propose a method to detect refinement errors in UML sequence diagrams using LTSA (Labeled Transition System Analyzer). The method integrates multiple sequence diagrams using hMSC (high-level Message Sequence Charts) into a sequence diagram. Then, the method translates the diagram into FSP representation, which is the input language of LTSA. The method also supports some combined fragment operators in the UML 2.0 specification. We applied the method to some examples of refined sequence diagrams and checked the correctness of refinement. As a result, we confirmed the method can detect refinement errors in practical time.

In this letter, an improved statistical simulation model with a new parameter computation method is proposed for Rayleigh fading channels. Compared with the existing simulators, the proposed model yields much higher simulation efficiency, while it can still obtain adequate approximations of the desired statistical properties.

In this letter, we propose a framework for scalable video multicast, which exploits the scalability of scalable video and the multiuser diversity of OFDMA systems. We further propose a resource allocation algorithm which guarantees the base-quality video for all users, and improves the transmission efficiency for users with good channel conditions.

A method for spatio-temporal resolution enhancement of video sequences based on super-resolution reconstruction is proposed. A new observation model is defined for accurate resolution enhancement, which enables subpixel motion in intermediate frames to be obtained. A modified optimization formula for obtaining a high-resolution sequence is also adopted.

Silver electrical contacts are separated at constant speed and break arcs are generated in a DC100 V–450 V/10 A resistive circuit. The transverse magnetic field of a permanent magnet is applied to the break arcs. Dependences of the arc duration, arc dwell time and arc lengthening time on the strength of the magnetic field and supply voltage are investigated. The characteristics of the re-ignition of the break arc are also discussed. Following results are shown. The arc duration D is increased due to the increase of the arc lengthening time tm when the supply voltage E is increased for each magnetic flux density Bx, because the arc dwell time ts is almost constant. The arc duration D is increased due to the increase of both of the arc lengthening time tm and the arc dwell time ts when the magnetic flux density Bx is decreased. The arc lengthening time tended to become long when the re-ignition of the break arc is occurred. The lengthening time tends to become longer when the duration tm1 from the start of the arc lengthening to the start of the re-ignition is increased. Re-ignitions occurred frequently when the magnetic flux density of the transverse magnetic field is increased and the supply voltage is increased.

This paper proposes a new on-demand routing protocol. It aims to establish a redundant route path containing intermediate nodes having relatively more synchronized neighbor nodes in a possible route. This approach can localize the effects of route failures and reduce route reconfiguration time by enhancing the reachability to the destination node without source-initiated route re-discoveries at route failures. Simulation results show that it has better performance than AODV and TORA.

Recently, Luo et al. proposed an efficient hierarchical identity based encryption (HIBE) scheme with constant size of ciphertexts, and proved its full security under standard assumptions. To construct the scheme, they used the dual system encryption technique of Waters, and devised a method that compresses the tag values of dual system encryption. In this paper, we show that the security proof of Luo et al. is wrong since there exists an algorithm that distinguishes whether it is a simulation or not.

3 dB bandwidth enhancement of single mode semiconductor lasers is confirmed numerically and experimentally when they are operated by intensity modulated signal light injection. 3 dB bandwidth is enlarged to 2.5 times of resonant frequency. The numerical analysis of rate equations predicts that the bandwidth enhancement is accomplished by the modal gain control of semiconductor lasers with injected intensity modulated signal light through non-linear gain coefficient term.

This paper presents a response time acceleration technique in a high-gain capacitive-feedback frontend amplifier (FA) for high output impedance sensors. Using an auxiliary amplifier as a unity-gain buffer, a sample-and-hold capacitor which is used for band-limiting and sampling the FA output is driven at the beginning of the transient response to make the response faster and then it is re-charged directly by the FA output. A condition and parameters for the response time acceleration using this technique while maintaining the noise level unaffected are discussed. Theoretical analysis and simulation results show that the response time can be less than half of the case without the acceleration technique for the specified settling error of less than 0.5%.

A model-based mutation testing (MBMT) approach enables to perform negative testing where test cases are generated using mutant models containing intentional faults. This paper introduces an alternative MBMT framework using pushdown automata (PDA) that relate to context-free (type-2) languages. There are two key ideas in this study. One is to gain stronger representational power to capture the features whose behavior depends on previous states of software under test (SUT). The other is to make use of a relatively small test set and concentrate on suspicious parts of the SUT by using MBMT approach. Thus, the proposed framework includes (1) a novel usage of PDA for modeling SUT, (2) novel mutation operators for generating PDA mutants, (3) a novel coverage criterion, and an algorithm to generate negative test cases from mutant PDA. A case study validates the approach, and discusses its characteristics and limitations.

Arc discharge generated by breaking electrical contact is considered as a main source of not only degradation of the electrical property but also an undesired electromagnetic (EM) noise. In order to clarify the effect of heated temperature on the bridge, arc-duration and the fluctuation of voltage, opening-waveforms at slowly separating silver-tin dioxide contact with holder heating are measured and discussed experimentally in this paper. Firstly, opening-waveforms are measured. Secondly, voltage fluctuation of the each arc-phase is discussed to extract the effect of the heated holder. The relationship between temperature of the heated holder and duration and fluctuation of the arc was investigated experimentally. It was revealed that as the initial temperature of the heated holder becomes higher, arc-duration becomes slightly longer. In addition, voltage fluctuation at the gaseous-phase decreases when the holder is heated. Consequently, the heated holder can suppress the voltage fluctuation even if its duration becomes slightly longer.

Performance of CSMA/CA wireless communication is severely affected by hidden terminal (HT) problem that results in failure of carrier sense and causes packet error due to collision. However, no mathematical analysis method for the HT problem has been available that takes into account actual radio environments including both fading and capture effect. This paper presents an analysis method that enables to well predict the probability of successful communication (PSC) and communication efficiency for CSMA/CA unicast communication including the interaction of data and ACK packets. Analysis of the PSC with two-dimensional HT distribution makes it easy to understand the influence of HT location and carrier sense level. Also it is shown that there is considerable difference on the PSC between fading and fading-free environments. The obtained results as well as the proposed analysis method are quite useful in CSMA/CA network design for WLAN and sensor network applications.

This paper focuses on the latest research of switching arc both in vacuum and SF6 substitutes in our group. The crucial characteristics of vacuum arc are illustrated, including the motion and distribution of single cathode spot and multiple cathode spots, the influence of axial magnetic field on arc plasma characteristics, the influence of composite magnetic field on cathode jets, and the study of anode activities. Meanwhile, the arc characteristics in SF6 and its substitutes (Ar, CO2 and N2) at different pressures and gap distances are investigated by experiments and simulation.

This paper develops a methodology of crosstalk analysis/measurement techniques for the design and fabrication of the MEMs (Micro-ElectroMichanical system) probe card. By introducing more ground pins into the connector pins, the crosstalk characteristics can be enhanced and a design guide for the parameters, such as pin's size and pitch is proposed to satisfy the given crosstalk limitation of -30 dB for reliable high speed signal transfer. The paper also presents a novel method to characterize scattering parameters of multiport interconnect circuits with a 4-port VNA (Vector Network Analyzer). By employing the re-normalization of scattering matrices with different reference impedances at other ports, data obtained from 4-port configuration measurements can be synthesized to build a full scattering matrix of the DUT (Device-Under-Test, MEMs probe connector pins). In comparison to the conventional 2-port VNA re-normalization method, proposed technique has two advantages: saving of measuring time, and enhanced accuracy even with open-ended unmeasured ports. A good agreement of the estimated and correct S parameters verifies the validness of the proposed algorithm.