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This paper examines the cloud computing for education (CCE) literature, and analyzes if the research is developing scientifically with adequate empirical validation. All aspects of empirical investigations covered in the literature are shown as weak, hence, the necessary scientific development of CCE requires extending its scope of interest, and involving scholars synergistically to create and maintain a “common research agenda.” Background: A need to develop research on CCE has been recognized, and considerable efforts made to create an accurate understanding of the development of its scope of interest, in terms of supporting pedagogical developments and processes for better quality of studies. Research Questions: This paper has three main aims: 1) to evaluate the scope of interest in the literature for CCE with specific reference to pedagogy and educational processes; 2) to analyze the characteristics of papers, specifically empirical studies, from the various points of view of the daily improvement activities of teachers and learners at all levels of education; and 3) to identify eventual research gaps to consider and stimulate new topics or further investigations. Methodology: This systematic mapping study review followed a rigorous, replicable process to collect and analyze representative studies of CCE. Findings: Differences are found across geographic areas in applying CCE infrastructure and technologies in educational institutions; few studies address CCE’s impact on pedagogic processes. The scope of interest in CCE is only partially covered; with empirical research being very shallow. Suggestions are made for more effective research on concerning the production and use of content. [ABSTRACT FROM AUTHOR]

In this paper, the influence of the stiffness and damping of real elastic shafts on the behavior of a multidrive system driving a tissue paper machine is investigated. The drive system consists of four dc motors, where two of them drive the Yankee drying cylinder and the other two drive the presses section. Six-pulse thyristor bridge power converters that are connected to the same power transformer supply the motors. The inertias of the motors and the driven machines, in conjunction with the shaft stiffness, form mechanical resonators. Thus, resonance phenomena may occur, which may lead to undesirable results. This particular case results to two three-mass and one five-mass systems. This paper presents an analysis of the resonance frequencies of two sections of the machine during startup and machine production, considering the shaft stiffness (shaft diameter, length, and thickness). The elastic shafts eliminate the ripple of the motor electromagnetic torque, which is transferred to the driven machine. The behavior of elastic shafts with different stiffness in the transmission system is studied. Moreover, the steady state and dynamic behavior of the system considering the influence of the elastic shafts and vibration analysis were investigated using simulation. A model algorithm for system simulation was developed using the MATLAB/SIMULINK software. Characteristic simulation results are presented and are expressed in terms of speed and torque response. Considering the resonance frequency analysis and simulation results, mechanical design guidelines can be given for the most significant drive components in order to avoid torsional oscillation resonance phenomena and minimize torsional oscillations of the drive system. [ABSTRACT FROM AUTHOR]

User interfaces to control networked household appliances are often inadequate. Either they are too simplistic or they are too complex and complicated relying on a PC-based interface. Therefore, a user interface that supports complex functionalities and is easy to use is required. In this article digital pen and paper are presented as a suitable interface. Digital pens are only marginally larger than their traditional counterparts, and digital paper is ordinary paper with an almost invisible unique pattern printed on it. Pen and paper are well known to users and thus an important barrier to the acceptance of networked appliances is removed. The approach is integrated with an Open Services Gateway Initiative (OSGi) gateway, thus allowing for flexibility with respect to the protocol used to communicate with the appliance. It is also shown how the approach can be applied to other appliances in and beyond the home. [ABSTRACT FROM AUTHOR]

Focuses on optimal approach to fault tolerant software system design.

This paper aims to provide a basis for the improvement of software estimation research through a systematic review of previous work. The review identifies 304 software cost estimation papers in 76 journals and classifies the papers according to research topic, estimation approach, research approach, study context and data set. A Web-based library of these cost estimation papers is provided to ease the identification of relevant estimation research results. The review results combined with other knowledge provide support for recommendations for future software cost estimation research, including 1) increase the breadth of the search for relevant studies, 2) search manually for relevant papers within a carefully selected set of journals when completeness is essential, 3) conduct more studies on estimation methods commonly used by the Software industry, and 4) increase the awareness of how properties of the data sets impact the results when evaluating estimation methods. [ABSTRACT FROM AUTHOR]

The International Computer and Software Applications Conference has celebrated its tenth anniversary in 1986. The conference has been very successful in attracting excellent papers and panels from both academia and industry. It continued the tradition and attracted superb papers for the following tracks: software quality, software engineering, software requirements, development environments, software techniques and knowledge-based systems.

The article focuses on formal method for open object-based distributed systems (FMOODS). Object-based distributed computing is now a well-established technique for constructing large, heterogeneous computing and telecommunication systems. Standard bodies and consortia have defined distributed object-based frameworks as a foundation for open distributed computing. Its advent brings new challenge and opportunities for the use and development of formal methods. The FMOODS conference series has acted as a forum for presentation of research that addresses these challenges. It seeks to investigate how formal methods can be used to specify, develop and verify open object-based distributed systems. The objective of FMOODS is to represent work at the convergence of three important and related fields that is formal methods, distributed systems and object-based technology. The convergence represents some of the latest advances in the field of distributed systems and provides links between a number of important communities.

In the paper, “semQA: SPARQL with Idempotent Disjunction” [4], the authors study the RDF query language SPARQL. In particular, they claim that some of the results presented in [1] are not correct. In this note, we refute the claims made in [4], and actually show that some of the formal results of [4] are incorrect. [ABSTRACT FROM PUBLISHER]

Focuses on the advantages of an electronic system Manuscript Central, a state-of-the-art Internet-based reviewing process. Adoption of the service by the Institute of Electrical and Electronics Engineers; Capability of the system in enabling the entire peer-review process to take place online; Introduction of temc.manuscript central.com Web site.

The nine papers in this special section focus on new developments in agile software and reports on applications for its use. A key aspect for the extensive use of agile software is that it supports developers with coping with the growing uncertainty and turbulence in technological and market environments. Feedback and change are at the core of Agile for a dynamic, evolving, and organic, rather than static, predefined, and mechanistic development process advocated by waterfall management. To create timely, high-quality, cost-efficient, and innovative solutions, Agile developers organized in small, colocated, autonomous teams, build and test software in rapid iterative cycles, actively involving users to gather feedback, updating the project scope, and plan "on-the-fly," using face-to-face communication as opposed to documentation. These papers contribute to the state-of-the-art of agile research by offering a rich, up-todate account of the dynamics occurring when expanding Agile into "not-just-software" contexts of the key challenges and perils related to the scaling and of the possible solutions to them. [ABSTRACT FROM AUTHOR]

In this paper, a self-adaptive protection system is proposed for adjusting the time dial (TD) of reclosers found in electrical power distribution systems (EPDSs). The self-adjustment is carried out in both phase and ground protection. The methodology considers the fuses along the feeder to obtain the fuse-saving philosophy. This feature allows less interference on the protection system already implemented by the electrical power distribution utilities. This methodology also allows using other frameworks, such as the estimation of the fault distance. The software used for computer modeling and simulation was PSCAD™/EMTDC™. The flexibility provided by the method, which allows the incorporation of new logic and changes in decision-making, resulted in an adaptive method with a good performance against different locations, types, and fault impedance. It also resulted in better coordination between the protection devices (PDs). The results compared with well-coordinated conventional protection have shown significant performance gain with the adaptive system. [ABSTRACT FROM AUTHOR]

The article presents an editorial that reflects on the author's role as editor-in-chief of the journal "IEEE Transactions on Software Engineering." He remarks that the journal encourages those involved in the field of software engineering to submit manuscripts for publication. There is no longer a length limit to papers published in the journal. The reviewing process for submitted papers is discussed. The author discusses members of the journal's editorial board and offers his thanks to those who have helped in his role at the journal.

This paper presents a novel nonintrusive protection scheme for fault classification of power transmission networks in a wide-area measurement system using fault information for decision making. The protection scheme is a noncommunication without global positioning system as it depends completely on locally measured currents for the nonintrusive fault monitoring (NIFM) using the power-spectrum-based hyperbolic S-transform (PS-HST). In this work, the HST is used to extract the high-frequency components of the current signals generated by an electric fault. To effectively select the HST coefficients (HSTCs) representing fault transient signals with increasing performance, a power spectrum of the HSTCs in different scales calculated by Parseval's theorem is proposed in this paper. Finally, back-propagation artificial neural networks and PS-HST are used to identify fault classes in power transmission networks. The proposed method is tested for different breaker on/off conditions by simulations using electromagnetic transients program software. The results obtained have proved that the proposed method is promising and demonstrate a high success rates and reliability for considering different fault resistances and inception times in NIFM applications. [ABSTRACT FROM AUTHOR]

The article discusses various reports published within the issue, including one by Matthew J. Bridges on the automatic parallelization of non-numeric programs and another by Naveen Neelankantam on hardware atomicity.

In this paper, a simple energy-efficient physical layer modulation scheme termed as random number modulation (RNM) is proposed. It is a class of new systems that harness the randomness of pseudo random number generators (RNGs) for efficient communication, and adds a new degree of freedom to digital communication systems. It is also highly adaptable to high-rate, low-latency, and low-rate, high-energy efficiency scenarios. This paper includes a detailed system model, preliminary performance analysis, and extended discussions. The performance of the proposed system is analyzed in terms of symbol and block error probabilities, energy efficiency, and latency. It is shown that there is a fundamental tradeoff between the energy efficiency and the latency of the proposed system, and they can be easily software programmable allowing devices to adapt to different circumstances and environments rapidly. Based upon the basic system model herein, it is anticipated that more sophisticated RNM systems can be developed. [ABSTRACT FROM PUBLISHER]

The annotation of significant events within soccer videos is a fundamental step in content-based soccer video retrieval. In this paper, we propose a soccer video annotation approach based on semantic matching with coarse time constraints, where video events and external text information (match reports) are synchronized using their semantic correspondence in the temporal sequence. Unlike the state-of-the-art soccer video analysis methods that assume that the time of an event’s occurrence is given precisely by the external text information, this paper considers the problem of annotating soccer videos using match reports with coarse-grained time information. The contributions of the proposed approach are: 1) we propose a more generalized approach that synchronizes video events with text descriptions using high-level semantics with coarse time constraints, rather than assuming that the timestamp is given exactly in the text description; 2) the detection of event boundaries is improved by attack–defense transition analysis (ADTA); 3) a robust and fast center circle detection algorithm is proposed for the classification of soccer field zones and ADTA; and 4) unlike conventional audio-based whistle detection, we propose a novel Hough-transform-based algorithm from the perspective of image processing. This allows the game start time to be detected, and further helps the synchronization of video and text events. The experimental results conducted on a large number of soccer videos validate the effectiveness of the proposed approach. [ABSTRACT FROM PUBLISHER]

This paper deals with a mathematical model of a gas discharge arrester, developed within the Matlab/Simulink program environment on the basis of physical and mathematical parameters. The model includes important physical phenomena regarding a gas discharge arrester, such as its overvoltage causing triggering, discharge processes, electric arc, and a possible repeated dielectric breakdown in gas due to the heat released from the arc to the gas. This paper includes computations for the operating conditions of a gas discharge arrester connected to an ac circuit. The computing results are compared with those measurements of electrical quantities performed on a gas discharge arrester. [ABSTRACT FROM AUTHOR]

In this paper, we present hardware and software implementations of flexible polar systematic encoders and decoders. The proposed implementations operate on polar codes of any length less than a maximum and of any rate. We describe the low-complexity, highly parallel, and flexible systematic-encoding algorithm that we use and prove its correctness. Our hardware implementation results show that the overhead of adding code rate and length flexibility is little, and the impact on operation latency minor compared with code-specific versions. Finally, the flexible software encoder and decoder implementations are also shown to be able to maintain high throughput and low latency. [ABSTRACT FROM AUTHOR]

Role assignment is a critical element in the role-based collaboration process. There are many constraints to be considered when undertaking this task. This paper formalizes the group role assignment problem when faced with the constraint of conflicting agents, verifies the benefits of solving the problem, proves that such a problem is a subproblem of the extended integer linear programming (x-ILP) problem, proposes a practical approach to the solution, and assures performance based on the results of experiments. The contributions of this paper include: 1) formalization of the proposed problem; 2) verification of the benefit achieved by avoiding conflicts in role assignment through simulation; 3) theoretical proof that conflict avoidance is a subproblem of the x-ILP problem that is nonpolynomial-complete; and 4) a practical solution based on the IBM ILOG CPLEX optimization package (ILOG) and verification of the scale of problems that can be solved with ILOG. The proposed approach is validated by simulation experiments. Its efficiency is verified by comparison with the previous exhaustive search-based approach. [ABSTRACT FROM PUBLISHER]

Security-sensitive usage models, such as implantable and wearable medical devices are prone to algorithmic cryptographic attacks as well as malicious implementation attacks. The cryptographic algorithms in these cryptosystems, such as lightweight block ciphers utilized in constrained applications, face significant tradeoff between the high level of security and the efficiency of their implementation metrics. For thwarting fault analysis attacks, among effective variants of active implementation attacks, and also to detect natural faults, efficient fault diagnosis schemes for these lightweight block ciphers are essential. In this paper, for the first time, we propose error detection schemes for lightweight block cipher, KLEIN, to ameliorate its error resiliency with low hardware complexity. The proposed fault diagnosis architectures are for linear and nonlinear components of this cipher. We also consider the notion of fault space transformation for lightweight cryptography and present its potential complications. The implementation of the proposed schemes through variants of Xilinx field-programmable gate arrays and the error coverage assessed with fault injection simulations show the effectiveness of the proposed schemes with acceptable footprints. [ABSTRACT FROM AUTHOR]

Thanks to relatively small public and secret keys, the Supersingular Isogeny Key Encapsulation (SIKE) protocol made it into the third evaluation round of the post-quantum standardization project of the National Institute of Standards and Technology (NIST). Even though a large body of research has been devoted to the efficient implementation of SIKE, its latency is still undesirably long for many real-world applications. Most existing implementations of the SIKE protocol use the Montgomery representation for the underlying field arithmetic since the corresponding reduction algorithm is considered the fastest method for performing multiple-precision modular reduction. In this paper, we propose a new data representation for supersingular isogeny-based Elliptic-Curve Cryptography (ECC), of which SIKE is a sub-class. This new representation enables significantly faster implementations of modular reduction than the Montgomery reduction, and also other finite-field arithmetic operations used in ECC can benefit from our data representation. We implemented all arithmetic operations in C using the proposed representation such that they have constant execution time and integrated them to the latest version of the SIKE software library. Using four different parameters sets, we benchmarked our design and the optimized generic implementation on a 2.6 GHz Intel Xeon E5-2690 processor. Our results show that, for the prime of SIKEp751, the proposed reduction algorithm is approximately 2.61 times faster than the currently best implementation of Montgomery reduction, and our representation also enables significantly better timings for other finite-field operations. Due to these improvements, we were able to achieve a speed-up by a factor of about 1.65, 2.03, 1.61, and 1.48 for SIKEp751, SIKEp610, SIKEp503, and SIKEp434, respectively, compared to state-of-the-art generic implementations. [ABSTRACT FROM AUTHOR]

Since modern cyber-physical power systems are vulnerable to coordinated wide-area cyber attacks, it is necessary to mitigate the potential risk as much as possible. At the planning stage, the defender can utilize software diversity, which is a common phenomenon that the cyber software of different substations comes from different competing vendors. Therefore, different kinds of software may not be exposed to the same zero-day security loophole, preventing the attacker from taking charge of multiple substations at the same time. In this paper, the optimal scheme of software deployment considering long-term risk mitigation is studied. Firstly, the framework of diversity-based cyber defense against malicious attacks is formulated. Secondly, the risk index based on representative attack patterns is constructed, which is the objective to be minimized. Thirdly, considering that the deployment scheme is long-term stable while the operating mode varies with time, we construct a multiobjective nonlinear stochastic programming to mitigate the average risk of operating modes. Then the optimization problem is solved by the multiobjective genetic algorithm. Lastly, results of the IEEE 39-node CPPS and and the Virtual European Grid demonstrate that the proposed method can considerably reduce the attack risk. [ABSTRACT FROM AUTHOR]

This paper presents an efficient method to calculate the magnetic forces on bodies in contact. The forces are computed through the local application of the virtual work principle on degenerated air-gap elements. The results from this method are compared with those from other software and validated with measurements on a permanent magnet setup. Not only is this technique very accurate, but it also reduces the computational burden related to the problematic meshing of thin layers. The implementation of this method in an open source finite element software having facilities for higher order elements and parallel computation unlocks a cost effective and effectual platform for an electromechanical computation of electromechanical devices and magnetic materials. [ABSTRACT FROM AUTHOR]

In this paper, we address identification of a class of multi-input single-output (MISO) linear time-invariant (LTI) discrete-time systems, where the MISO system is composed of several single-input single-output (SISO) LTI systems and only the sum of the output of each SISO system can be measured. By exciting one SISO system and employing periodic inputs to the remaining SISO systems, we decompose the MISO system into the excited SISO system where its input and output can be calculated from the measured data. As such, the original parameters for each SISO system can be estimated using the well-established identification techniques. The proposed method using periodic inputs is also extended to identification beyond the Nyquist frequency. Both simulation and experimental results on identification of actuators in the dual-stage hard disk drive are carried out to demonstrate the efficacy of the proposed approach. [ABSTRACT FROM AUTHOR]

Over the past ten years, human re-identification has received increased attention from the computer vision research community. However, for the most part, these research papers are divorced from the context of how such algorithms would be used in a real-world system. This paper describes the unique opportunity our group of academic researchers had to design and deploy a human re-identification system in a demanding real-world environment: a busy airport. The system had to be designed from the ground up, including robust modules for real-time human detection and tracking, a distributed, low-latency software architecture, and a front-end user interface designed for a specific scenario. None of these issues are typically addressed in re-identification research papers, but all are critical to an effective system that end users would actually be willing to adopt. We detail the challenges of the real-world airport environment, the computer vision algorithms underlying our human detection and re-identification algorithms, our robust software architecture, and the ground-truthing system required to provide the training and validation data for the algorithms. Our initial results show that despite the challenges and constraints of the airport environment, the proposed system achieves very good performance while operating in real time. [ABSTRACT FROM PUBLISHER]

Events of interest to Computer Society members. [ABSTRACT FROM AUTHOR]

In order to provide dynamic adaptation of the performance/energy tradeoff, systems today rely on heterogeneous multicore architectures (different micro-architectures on a chip). These systems are limited to single-ISA approaches to enable transparent migration between the different cores. To offer more tradeoff, we can integrate statically scheduled micro-architecture and use dynamic binary translation (DBT) for task migration. However, in a system where performance and energy consumption are a prime concern, the translation overhead has to be kept as low as possible. In this paper, we present Hybrid-DBT, an open-source, hardware accelerated DBT system targeting VLIW cores. Three different hardware accelerators have been designed to speed-up critical steps of the translation process. Experimental study shows that the accelerated steps are two orders of magnitude faster than their software equivalent. The impact on the total execution time of applications and the quality of generated binaries are also measured. [ABSTRACT FROM AUTHOR]

Being the first codes achieving the capacity of symmetric binary-input discrete memoryless channels, polar codes have been favorable and standardized for enhanced mobile broadband (eMBB) control channels. In future mobile communications, the entire system is required to be flexible and adaptive to varying scenarios. Therefore, efficient software implementation of polar decoder is expected. Existing software successive cancellation list polar decoder can achieve good performance but with a good memory consumption. For short control channel codes, a more memory-efficient alternative is sphere decoder, but its latency gives rise to another issue. Equipped with a breadth-first search to keep a fixed complexity, list sphere decoder (LSD) is also considered. To improve the performance of LSD, a software LSD with synchronous determination is proposed in this paper. We precalculate the synchro sets to improve the decoding, which leads to a performance gain. Meanwhile, the decoding process is simplified due to the precalculation, which attains even lower complexity. Implemented with C++, the proposed decoder can achieve up to 2 dB performance gain compared with the existing LSD. [ABSTRACT FROM AUTHOR]

Embedded systems present stringent and often conflicting requirements. On the one side, the need for high performance within a tight energy budget favors inflexible Application Specific Integrated Circuit (ASIC) implementations; on the other side, a short time-to-market demands programmability. Hybrid architectures such as special-purpose customized processors represent an attractive solution, as they are programmable by software, but use dedicated hardware to accelerate parts of the computation. In such a scenario, the capability of automatically identifying the computation parts to be realized in hardware is highly desirable, in order to reduce design time and effort. This paper aims at advancing the state-of-the-art in this field. We recognize that subgraphs of control flow graphs having a single input control point and a single output control point, that we call regions, are good targets for the synthesis of application specific hardware accelerators. We therefore provide a method to identify them and an LLVM-based toolchain (named RegionSeeker) that, analyzing a software application, automatically selects its most profitable regions given an area constraint. Experimental evidence shows that the accelerators identified by RegionSeeker provide a speedup of up to $4.6\boldsymbol {\times }$ and, on average, approximately 30% higher speedup is achieved compared to state-of-the-art identification techniques. [ABSTRACT FROM AUTHOR]

In recent years, misconfigurations have become one of the major causes of software system failures, resulting in numerous service outages. What is worse, misconfigurations are also costly to diagnose and troubleshoot. This remains a great challenge for sysadmins (system administrators) to detect, diagnose, or troubleshoot these misconfigurations. Unlike software bugs, misconfigurations are more vulnerable to sysadmins’ mistakes. Developers and researchers are attempting to improve system reactions to misconfigurations to ease the burden of sysadmins’ diagnoses. Such efforts would greatly benefit from the techniques that can comprehensively detect bad system reactions through injected misconfigurations. Unfortunately, few such studies have achieved the above goal in the past, primarily because they only relied on generic alterations and failed to find a way to systematically generate misconfigurations. In this paper, we study eight mature open-source and commercial software packages and summarize a fine-grained classification of option types. Based on this classification, we use Augmented Backus–Naur Form to summarize and extract syntactic and semantic constraints of each type. In order to generate comprehensive misconfigurations in the test systems, we propose misconfiguration generation methods for our constraints. We implement a tool named Configuration Vulnerability Detector (ConfVD) to conduct misconfiguration injection and further analyze the systems’ reaction abilities to various misconfigurations. We carried out comprehensive analyses upon Apache Httpd, MySQL, PostgreSQL, and Yum. The results of our analysis show that our option classification covers 96% of 1582 options from the above-mentioned systems. Our constraints are more fine grained than previous works and their accuracy was found to be 91% (ascertained by manual verification). Our technique could improve generic alteration approaches without constraints, and we found that ConfVD could find nearly three times the bad reactions that were found by ConfErr. In total, we found 65 bad reactions from the systems being tested and our fine-grained constraints contributed 27.7% more bad reactions than techniques only using coarse-grained constraints. [ABSTRACT FROM AUTHOR]

This paper presents analytical expressions for steady-state waveforms, output power, and power conversion efficiency for the class-E inverter outside the class-E zero-voltage switching and zero-derivative switching conditions. The analytical expressions in this paper include the MOSFET-body-diode effect. By carrying out PSpice simulations and circuit experiments, it is shown that the analytical predictions agree with the simulated and experimental results quantitatively, which indicates the validity of the analytical expressions. Additionally, the switching-pattern distribution maps are also given by using the analytical waveform equations. [ABSTRACT FROM PUBLISHER]

This paper compares the application of two deterministic and three nondeterministic optimization algorithms to global transformer design optimization (TDO). Two deterministic optimization algorithms (mixed-integer nonlinear programming and heuristic algorithm) are compared to three nondeterministic approaches (harmony search, differential evolution, and genetic algorithm). All these algorithms are integrated in design optimization software applied and verified in the manufacturing industry. The comparison yields significant conclusions on the efficiency of the algorithms and the selection of the most suitable one for the TDO problem. [ABSTRACT FROM AUTHOR]

The article discusses various reports published within the issue, including one by Ray-Yaung Chang, Andy Podgurski, and Jiong Yang on discovering neglected conditions in computer software by mining dependence graphs, one by Marcelo d'Amorim, Steven Lauterburg, and Darko Marinov on speeding up state-space exploration, and one by Graham Hughes and Tevfik Bultan on interface grammars for modular software model checking.

This paper studies robust resource-allocation algorithm design for a multiuser multiple-input–single-output (MISO) cognitive radio (CR) downlink communication network. We focus on a secondary system that provides wireless unicast secure layered video information to multiple single-antenna secondary receivers. The resource-allocation algorithm design is formulated as a nonconvex optimization problem for the minimization of the total transmit power at the secondary transmitter. The proposed framework takes into account a quality-of-service (QoS) requirement regarding video communication secrecy in the secondary system, the imperfection of the channel state information (CSI) of potential eavesdroppers (primary receivers) at the secondary transmitter, and a limit for the maximum tolerable received interference power at the primary receivers. Thereby, the proposed problem formulation exploits the self-protecting architecture of layered transmission and artificial noise generation to ensure communication secrecy. The considered nonconvex optimization problem is recast as a convex optimization problem via semi-definite programming (SDP) relaxation. It is shown that the global optimal solution of the original problem can be constructed by exploiting both the primal and the dual optimal solutions of the SDP-relaxed problem. In addition, two suboptimal resource-allocation schemes are proposed for the case when the solution of the dual problem is unavailable for constructing the optimal solution. Simulation results demonstrate significant transmit power savings and robustness against CSI imperfection for the proposed optimal and suboptimal resource-allocation algorithms employing layered transmission compared to baseline schemes employing traditional single-layer transmission. [ABSTRACT FROM PUBLISHER]

Several transient stability software packages are widely used for power grid planning and operations. Prior research and software documentations have shown that packages can vary in the implementations of dynamic models, and hence could potentially yield different results for the same system simulation. This paper presents a systematic methodology to determine the sources of the discrepancies seen in results obtained from different transient stability packages. This methodology can be applied to various types of dynamic models and is illustrated with generator-associated dynamic models in this paper. Consistent metrics, data mining techniques, and engineering heuristics are used to determine the discrepancy sources. This hybrid top-down+bottom-up method has been implemented on a practical, large-system case to demonstrate its scalability and transferability to real-world system studies. [ABSTRACT FROM AUTHOR]

In this paper, the analysis, design, and implementation of a novel rotor position estimator for the control of variable-speed switched reluctance generators (SRG5) are presented. The rotor position is obtained using the unsaturated instantaneous inductance. This unsaturated inductance is estimated calculating the slope of the phase current and using a reducedsize neural network (NN) whose inputs are the average current and the saturated inductance. The proposed estimator requires less processing time than traditional methods and can be fully implemented using a low-cost DSP with very few additional analog/digital components. The rotor position estimator presented in this paper can be applied to a wind energy conversion system where the SRG is used as a variable-speed generator. This application is currently being studied because the SRG has well-known advantages such as robustness, low manufacturing cost, and good size- to-power ratio. Simulation and experimental results are presented using a 2.5-kW 8/6-SRG prototype. [ABSTRACT FROM AUTHOR]

Software energy estimation is a critical step in the design of energy-efficient embedded systems. Instruction-level simulation techniques, despite several advances, remain too slow for iterative use in system-level exploration and for embedded systems with high software complexity. In this paper, we propose a methodology called hybrid simulation, which combines instruction set simulation with selective native execution (execution of some parts of the program directly on the simulation host computer). Hybrid simulation attempts to overcome the disadvantages of instruction-level simulation (low speed) and pure native execution (estimation accuracy and inapplicability to target-dependent code) while exploiting their advantages. In order to perform the energy estimation for natively executed subprograms, hybrid simulation leverages previously developed techniques for software energy macromodeling. This paper identifies and addresses the main challenges involved in hybrid simulation, including control/data transfer and memory synchronization between instruction set simulation and native execution domains, estimation errors due to macromodeling, and simulation overheads for switching between domains. We present an automatic tool flow for hybrid simulation, which analyzes a given program and selects functions for native execution in order to achieve maximum estimation efficiency while limiting estimation error. Our tool generates native ‘drop-in’ modules that are linked into the instruction set simulator (ISS) and simulation ‘stubs’ that are linked with the application to facilitate hybrid simulation. We have applied the proposed hybrid simulation methodology to a variety of embedded software programs, resulting in average speedups of 25.2× (maximum of 124×) and estimation error of only 3% (maximum of 6%), as compared to one of the fastest publicly available ISSs. [ABSTRACT FROM AUTHOR]

The article focuses on deadlocks in operating systems. Deadlocks constitute an important issue in the design and operation of various computer-integrated systems. These systems range from automated production system and transportation system to computer operating systems, concurrent software systems, computer networks and distributed database systems. Many of these systems include human in a loop. A deadlock arises when two or more processes in the system, each holding some resources, request the resources occupied by one another such that a circular wait is formed. In the presence of deadlocks, the system loses its partial or total operational functionality and may increase its operational cost.

Grain is one of three hardware-oriented finalists of the eSTREAM Project. A nonlinear feedback shift register (NFSR) in Grain-like structure is a cascade connection of a linear feedback shift register (LFSR) into an NFSR, in which the characteristic polynomial of the LFSR is primitive and the feedback function of the NFSR is nonsingular. In 2011 Hu and Gong pointed out that the period of the sequence generated by an NFSR in Grain-like structure is a multiple of the period of the sequence generated by its LFSR if the initial state of the LFSR is nonzero. Meanwhile, they proposed an open problem: for fixed feedback functions of an NFSR and an LFSR, determine whether the sequences generated by the NFSR in Grain-like structure can achieve the minimum period, i.e., the period of the LFSR, when the initial state of the LFSR is nonzero, and if they can achieve, provide at least one pair of the initial states of the NFSR and LFSR. Clearly, from a security point of view, it is not preferable if the sequences generated by an NFSR in Grain-like structure achieve the minimum period. This paper converts the open problem into a problem of solving an integer equation with respect to two unknown integers that uniquely correspond to the initial states of the NFSR and LFSR, by viewing the NFSR as a Boolean control network. Based on the integer equation, this paper shows that for any given initial state of an $n$ -stage NFSR and any given nonzero initial state of an $m$ -stage LFSR, the probability that the sequence generated by the NFSR in Grain-like structure achieves the minimum period $2^{m}-1$ is at most $2^{-n}$. This implies that the probability of the cascade connection used in Grain achieving the minimum period is very small. [ABSTRACT FROM AUTHOR]

This paper discusses the marginal line loss approximation in the dc optimal power flow (DCOPF) and proposes a new methodology that improves the accuracy of current practices. In practice, the DCOPF solution may have significant differences compared to the ac base point that determines marginal losses, and this paper provides the only published example that illustrates this problem to our knowledge. The proposed methodology updates the marginal losses without solving a new ac base point so that the optimal solution accurately reflects system losses. Previously proposed methodologies require nonlinear programming solvers, additional ac power flow solutions, or are less accurate compared to actual losses, and they only give results for one or two test networks. This paper provides results on nine different test networks. The key advantage of the proposed methodology is that it can be easily integrated into current market software. [ABSTRACT FROM AUTHOR]

Fast and accurate optical flow estimation is a challenging problem in computer vision. In this paper, we present a novel model to solve the optical flow problem by combining the strengths of the Split Bregman method with the advantages of an efficient variational framework. It allows us to employ different regularization tensors for the Split Bregman regularizer to preserve motion discontinuities. Simultaneously, a novel nonlocal Split Bregman method with adaptive support weights is also developed for the smoothness regularization to preserve motion details, repel outliers, enhance contrast, and reduce motion blurring and staircase effect. The proposed algorithm shows significant improvements in preserving sharp flow edges and important motion details. Most of all, it requires only a few iterations to achieve fast convergence and runs faster than the classic TV-L1 flow method. Our method significantly outperforms the current state-of-the-art methods on the challenging MPI-Sintel dataset and shows good performance on the Kitti flow 2015 and Middlebury datasets. [ABSTRACT FROM PUBLISHER]

IPC (Inter-Process Communication) is a widely used operating system (OS) technique that allows one process to invoke the services of other processes. The IPC participants may share the same OS (internal IPC) or use a separate OS (external IPC). Even though a long line of researches has optimized the performance of IPC, it is still a major factor of the run-time overhead of IPC-intensive applications. Furthermore, there is no one-size-fits-all solution for both internal and external IPC. This paper presents SkyBridge, a general communication technique designed and optimized for both types of IPC. SkyBridge requires no involvement of the privileged software (the kernel or the hypervisor) and enables a process to directly switch to the virtual address space of the target process, regardless of whether they are running on the same OS or not. We have implemented SkyBridge on two microkernels (seL4 and Google Zircon) as well as an open-source serverless hypervisor (Firecracker). The evaluation results show that SkyBridge improves the latency of internal IPC and external IPC by up to 19.6x and 1265.7x, respectively. [ABSTRACT FROM AUTHOR]

Stereo vision is a well-known technique for acquiring depth information. In this paper, we propose a real-time high-quality stereo vision system in field-programmable gate array (FPGA). Using absolute difference-census cost initialization, cross-based cost aggregation, and semiglobal optimization, the system provides high-quality depth results for high-definition images. This is the first complete real-time hardware system that supports both cost aggregation on variable support regions and semiglobal optimization in FPGAs. Furthermore, the system is designed to be scaled with image resolution, disparity range, and parallelism degree for maximum parallel efficiency. We present the depth map quality on the Middlebury benchmark and some real-world scenarios with different image resolutions. The results show that our system performs the best among FPGA-based stereo vision systems and its accuracy is comparable with those of current top-performing software implementations. The first version of the system was demonstrated on an Altera Stratix-IV FPGA board, processing 1024 $\times $ 768 pixel images with 96 disparity levels at 67 frames/s. The system is then scaled up on a new Altera Stratix-V FPGA and the processing ability is enhanced to $1600 \times 1200$ pixel images with 128 disparity levels at 42 frames/s. [ABSTRACT FROM PUBLISHER]

Multi-core processors have been adopted in modern embedded systems to meet the ever increasing performance requirements. Scratchpad memory (SPM), a software-controlled on-chip memory, has been used in embedded systems as an alternative to hardware-controlled cache due to its advantage in die area, power consumption, and timing predictability. SPMs in multi-core systems can be accessed by both local core and remote cores. In order to alleviate data contention on a SPM unit, multi-port SPMs are employed in multi-core systems. In such systems, proper task scheduling and data assignment can significantly improve the overall performance by exploring the parallelism of computation tasks and concurrent data accesses on SPMs. Since scheduling for multi-core systems is NP-Complete in general. In this paper, we propose an ILP formulation to optimally determine the task scheduling and data assignment on multi-core systems with multi-port SPMs. Since ILP takes exponential time to finish, we also propose a heuristic method, including the task assignment with remote access reduced (TARAR) algorithm and the minimum memory access cost (MMAC) algorithm, to obtain near optimal solutions within polynomial time. According to the experimental results, the ILP formulation can improve the system performance by 23.02 percent over the HAFF algorithm on average, while the heuristic algorithm can improve the system performance by 16.48 percent over HAFF on average. [ABSTRACT FROM AUTHOR]