Scientia Iranica
Year:2019 | Volume:26 | Issue:3 (Transactions D: Computer Science and Engineering and Electrical Engineering)|Papers Count:15

In software programs, most of the time, there is a chance for occurrence of faults in general, and exception faults in particular. Localizing those pieces of code that are responsible for a particular fault is one of the most complicated tasks, and it can produce incorrect results if done manually. Semi-automated and fully-automated techniques have been introduced to overcome this issue. However, despite recent advances in fault localization techniques, they are not necessarily applicable to Android applications because of their special characteristics such as context-awareness, use of sensors, being executable on various mobile devices, limited hardware resources, etc. To this aim, in this paper, a semi-automated hybrid method is introduced that combines static and dynamic analyses to localize exception faults in Android applications. Our evaluations of nine open source Android applications of di erent sizes with various exceptions show that the technique proposed in this paper can correctly identify root causes of the occurred exceptions. These results indicate that our proposed approach is e ective in practice in localizing exception faults in Android applications.

This paper proposes an approach to improving color images su ering from low dynamic range by employing both histogram matching and histogram stretching techniques. In the  rst stage, the color image was transformed from RGB into HSV color space, in which the color information was separated from intensity. Then, an appropriate reference image was selected by comparing component V of the enhanced image with component V of the database images using a similarity measure. The selected image was used as the target image in histogram matching algorithm for enhancement. In the second stage, components V and S were linearly stretched in order to recover the image color information. Finally, using the treated V and S components and untreated component of H, the enhanced image was obtained in RGB color space by inverse transform. The qualitative and quantitative results showed that the contrast and color of the resultant image were greatly improved using the proposed method, which outperformed the current state-of-the-art methods.

This paper studies the problem of Simultaneous Sparse Approximation (SSA). This problem arises in many applications that work with multiple signals maintaining some degree of dependency, e. g., radar and sensor networks. We introduce a new method towards joint recovery of several independent sparse signals with the same support. We provide an analytical discussion of the convergence of our method, called Simultaneous Iterative Method (SIM). In this study, we compared our method with other group-sparse reconstruction techniques, namely Simultaneous Orthogonal Matching Pursuit (SOMP) and Block Iterative Method with Adaptive Thresholding (BIMAT), through numerical experiments. The simulation results demonstrated that SIM outperformed these algorithms in terms of the metrics Signal to Noise Ratio (SNR) and Success Rate (SR). Moreover, SIM is considerably less complicated than BIMAT, which makes it feasible for practical applications such as implementation in MIMO radar systems.

The fractional-order differential equations (FDEs) have the ability to model the real-life phenomena better in a variety of applied mathematics, engineering disciplines including diffusive transport, electrical networks, electromagnetic theory, probability and so forth. In most cases, there are no analytical solutions therefore a variety of numerical methods have been developed for the solution of the FDEs. In this paper, we derive the numerical solutions of the various fractional-order Riccati type differential equations using the Euler Wavelet Method (EWM). The Euler wavelet operational matrix method converts the fractional differential equations to a system of algebraic equations. Illustrative examples are included to demonstrate the validity and efficiency of the technique.

To mitigate the high peak-to-average power ratio (PAPR) of discrete multi-tone (DMT) modulation in polymer optical fibers (POF) communication systems, a novel DMT scheme based on Jacket matrix spreading (JS) is proposed. Approximations of PAPR distribution for DMT signals are accurately presented. Single band JS-DMT and multi-band (MB)-JS-DMT are introduced in POF transmission link for PAPR reduction. Offline processing and simulations are adopted to investigate the performance of these new schemes with regard to the PAPR reduction, power spectral density (PSD), data rate and bit error rate (BER). The results demonstrate that, applying the JS methodology, up to 4dB PAPR reduction is achieved. JS-DMT is sensitive to the bandwidth range whereas MB-JS-DMT owns the robustness ability against fiber nonlinearity. Compared with some well known PAPR reduction techniques, the proposed schemes can be easily applied to the DMT modem and achieve the PAPR reduction efficiently without degrading the BER, data rate and PSD performance, which demonstrate the feasibility and validity of these two methods in POF transmission.

This paper aims to study the effect of the hourly demand response (DR) on security-constraint unit commitment (SCUC) problem with considering economic and security objectives. The demand side participation can solve some of the electricity market problems. Here, DR is take into consideration as one of the demand side management (DSM) parts. The DR is consist of fixed and responsive loads. The fixed loads satisfy in any circumstance and responsive loads can curtail or shift to other operating hours. The combination of SCUC with DR is a complex and the mixed integer non-linear problem. The bender’ s decomposition is used as an optimization technique for solve this problem. This technique solves the problem by decompose it into master and sub problems. One of the effective of this manner is reducing the processing time. The performance and effectiveness of the proposed method are demonstrated on 6-, 24-and 118-bus test systems.

Single-phase voltage source inverters (SP-VSIs) are widely used in grid connected solar photovoltaic (PV) systems. This paper deals with the dynamic modeling and stability analysis of single-phase grid connected PV inverters taking the PLL dynamics into account. The PLL structure employed in this paper includes two control branches; the main branch, known as phase estimation loop, extracts the phase and frequency of the grid voltage and the other branch, known as voltage peak estimation loop, determines the grid voltage amplitude. In this way, the paper first proposes design considerations for the dc-link voltage control and PLL control loops. Then, unified dynamic modeling of the SP-VSI system comprising PLL, dc-link dynamics and grid is presented and linearized block diagram of the whole system is extracted. The linearized block diagram depicts the interaction between the control loops of the PLL and dc-link system, where the PLL control loops consist of phase/frequency and amplitude estimation loops of the grid voltage. Next, the small signal stability of the full system is presented, and impacts of grid strength, operating point, and PLL closed loop bandwidth on the performance of SP-VSI are investigated by the modal analysis and time domain simulations.

Maintaining network stability and encouraging generation companies to involve in stability maintaining are major concerns of independent system operator (ISO) in deregulated power system. Excitation system of synchronous generators is effective and well-known equipment which has a significant effect on network stability. Therefore, improving performance of this system can enhance network stability. But utilizing of the methods, which improve performance of excitation system, imposes cost on generation companies. This paper proposes a motivation mechanism for enhancing transient stability which encourages generation companies to improve performance of excitation system. In this mechanism beside excitation system response improving methods, a transient stability constrained optimal power flow is solved in order to ensure maintaining transient stability in different contingencies. A 4-buses test system, the IEEE 14-buses test system, and the IEEE 118-buses test system are used to illustrate effectiveness of the proposed mechanism. Implementation results show that the proposed mechanism not only provides required transient stability margin with minimum operation cost, but also does not restrict generators production capability.

This paper offers a novel variant to the existing symbiotic organisms search (SOS) algorithm, to address optimal power flow (OPF) problems considering effects of valve-point loading (VE) and prohibited zones (POZ). Problem formulation includes minimization of cost, loss, voltage stability index (VSI) and voltage deviation (VD) and simultaneous minimization of their combinations. Quadratic cost function, effects of VE and effects of both VE and POZ have been considered. OPF formulation considering effects of both VE and POZ are not yet available in the literature. Efficacy of SOS in resolving OPF is recognized in the literature. An opposition based learning technique named quasi-reflection, is merged into existing SOS to enhance its prospects of getting nearer to superior quality solution. The proposed algorithm, named quasi-reflected symbiotic organisms search (QRSOS), is assessed for IEEE 30 and IEEE 118 bus test systems. It shows promising results in reducing the objective function values of both the systems by large margins (78. 98 % in case of VD when compared to SOS and NSGA-II and 46. 06 % in case of loss as compared to QOTLBO in IEEE 30 and IEEE 118 bus respectively). QRSOS also outperformed its predecessors, in terms of convergence speed and global search ability.

In this paper, the observer design method for linear and nonlinear singular discrete-time systems with constant time-delays is proposed. By constructing appropriate Lyapunov– Krasovskii functional and using linear matrix inequality (LMI) technique, the asymptotic convergence criterion is developed in terms of LMIs, which can be solved numerically using MATLAB® LMI® toolbox. The sufficient condition for the existence of a full-order observer is obtained and the states are estimated using Schur complement and S-procedure lemma very well. Moreover, an extension procedure for observer design of singular linear system with time-varying delay is presented. Simulation results are included to prove the efficiency of the suggested approach.

In broadcast encryption schemes, a distribution center broadcasts an encrypted message to a subset chosen from a universe of receivers and only the intended users are able to decrypt the message. Most broadcast encryption schemes do not provide anonymity and the identities of target receivers are sent in plaintext. However, in several applications, the authorized users’ identities have the same sensitivity as the broadcasted messages. Yu, Ren and Lou (YRL) considered this issue and introduced an e€icient anonymous a‚ribute-based broadcast encryption scheme. In this paper, we first propose an a‚ack on the YRL scheme and showthat the unauthorized receivers can also decrypt the broadcasted message. Next, we propose the Improved-YRL scheme and prove that it achieves anonymity and semantic security under adaptive corruptions in the chosen ciphertext se‚ing. The proof is provided using the dual system encryption technique and is based on three complexity assumptions in composite order bilinear maps. The Improved-YRL scheme is a step forward in solving the long-standing problem of secure and low overhead anonymous broadcast encryption.

The paper presents a procedure to model a PIN diode RF switch using a fullwave EM solver, HFSS. It utilizes the switch to build a simple partial ground plane antenna with an omnidirectional radiation pattern. The proposed antenna has the ability to tune the frequency from the ultra-wideband to narrowband mode. The frequency recon gurability is accomplished by incorporating a rectangular slot resonator and a PIN diode RF switch embedded in the partial ground plane. The antenna demonstrates 􀀀 10 dB impedance bandwidth from 500 MHz to 6 GHz in the ultra-wideband mode and 1. 125 GHz to 2 GHz in the narrowband mode. A parasite is stacked in the ground plane to improve the impedance matching, and a rectangular slot is fused to explore the bandwidth-limiting possibility of the antenna. The optimization of the antenna is done by a full-wave EM solver, HFSS; moreover, Speci c Absorption Rate (SAR) of the antenna is examined using the equivalent at tissue phantom. A prototype of the proposed antenna is fabricated, and execution is accepted by measured results. The proposed antenna has a simple and miniature structure, low SAR (0. 41 W/kg), an omnidirectional pattern, and low cross polarization (<􀀀 15 dB in E-plane and <􀀀 30 dB in H-plane).

This paper presents a new technique for mean square asymptotic reference tracking of nonlinear dynamic systems over Additive White Gaussian Noise (AWGN) channel. The nonlinear dynamic system has periodic outputs to sinusoidal inputs and is cascaded with a bandpass filter acting as encoder. Using the describing function method, the nonlinear dynamic system is represented by an equivalent linear dynamic system. Then, for this system, a mean square asymptotic reference tracking technique including an encoder, decoder and a controller is presented. It is shown that the proposed reference tracking technique results in mean square asymptotic reference tracking of nonlinear dynamic systems over AWGN channel. The satisfactory performance of the proposed reference tracking technique is illustrated using practical example simulations.

In this paper, a fuzzy analog controller circuit is provided for the inverted Pendulum problem which resulted in a simple analog circuit simply does the act of controlling without requiring to any processing structure. In other words, in case of constructing the proposed circuit, a small analog chip controls the inverted pendulum. For this purpose, the first step is the study of the dynamic model of the inverted pendulum and then a fuzzy controller is designed systematically. In the following, the number of membership functions and the formation of them are designed. In addition, the different MFs and different numbers are examined for each variable and the most efficient structure is selected as fuzzy controller. To assess efficiency of designed fuzzy controller, the controller is simulated in Simulink and then this design is implemented at transistor level in TSMC 0. 18µ m CMOS technology. In this work, the MFs, the circuits for realization of the knowledge-based and defuzzification circuits are designed in current mode. The proposed circuits are simulated and evaluated in Advanced Design System software based on CMOS technology. Simulation results show that the inverted pendulum is controlled with high accuracy and high speed, meanwhile the controllers have low power consumption and good robustness to outer large and fast disturbance rather than the previous works.

In this paper, we consider a secure network coding problem in which some secret keys are shared among legitimate nodes, and there exists an eavesdropper which is able to hear a subset of links. We show the equivalency of secure network coding under weak and strong secrecy conditions. For linear network coding, we show a stronger result: equivalency of "perfect secrecy and zero-error constraints" to "weak secrecy and $\epsilon$-error constraints". This is a secure version of the result obtained by Langberg and Effros, on the equivalence of zero-error and $\epsilon$-error regions in the network coding problem with co-located sources. Jalali and Ho exploit extractor functions to prove the weak and strong rate region equivalency for this network; however, to prove this equivalency, we develop some tools in random binning and prove the equivalency in a slightly more general setting.