nils-herrmann/clean_scirepeval huggingface dataset:
Model of a five-phase induction machine allowing for harmonics in the air-gap field. Part I. Parameter determination and general equations

This paper presents the mathematical model of a five-phase induction machine including the effects of higher space and time harmonics in the air-gap field. It is well known that these harmonic waves play a decisive role in the behavior of machines with more than three phases. This first part of a two-part paper discusses the calculation of the main parameters where these are derived analytically, and results are compared with values obtained by finite element analysis. The main parameters used in deriving the model are the self and mutual stator and rotor inductances. Based on the field distribution produced by stator and rotor, all the field harmonics are included in a direct and simple way in the self-inductances. The mutual inductances are obtained from a Fourier-series description of the air-gap field, resulting in a different inductance for each harmonic field. A discussion of the general equations for the induction machine follows. In the second part of the paper, these equations are simplified using known axis transformations, which result in equivalent d-q models and circuits for given harmonic groups. In their final form, the equations and corresponding equivalent circuits are well suited for purposes of simulation of five-phase machine behavior and developing new control strategies including higher space and time harmonics.
Data Coherence Analysis and Optimization for Heterogeneous Computing

Although heterogeneous computing has enabled impressive program speed-ups, knowledge about the architecture of the target device is still critical to reap full hardware benefits. Programming such architectures is complex and is usually done by means of specialized languages (e.g. CUDA, OpenCL). The cost of moving and keeping host/device data coherent may easily eliminate any performance gains achieved by acceleration. Although this problem has been extensively studied for multicore architectures and was recently tackled in discrete GPUs through CUDA8, no generic solution exists for integrated CPU/GPUs architectures like those found in mobile devices (e.g. ARM Mali). This paper proposes Data Coherence Analysis (DCA), a set of two data-flow analyses that determine how variables are used by host/device at each program point. It also introduces Data Coherence Optimization (DCO), a code optimization technique that uses DCA information to: (a) allocate OpenCL shared buffers between host and devices; and (b) insert appropriate OpenCL function calls into program points so as to minimize the number of data coherence operations. DCO was implemented in AClang LLVM (www.aclang.org) a compiler capable of translating OpenMP 4.X annotated loops to OpenCL kernels, thus hiding the complexity of directly programming in OpenCL. Experimental results using DCA and DCO in AClang to compile programs from the Parboil, Polybench and Rodinia benchmarks reveal performance speed-ups of up to 5.25x on an Exynos 8890 Octacore CPU with ARM Mali-T880 MP12 GPU and up to 2.03x on a 2.4 GHz dual-core Intel Core i5 processor equipped with an Intel Iris GPU unit.
A robust discrete-time controller for DC-AC inverters

This paper presents a robust control strategy for DC-AC power inverters based on the linear matrix inequality (LMI) framework. More precisely, a constant discrete-time state feedback controller is proposed taking into account the average model. The strategy assures the local stability of the closed-loop system for all admissible linear load variation while minimizing the effects of nonlinear loads. Practical results show the advantages of the approach over classical control design techniques.
A fast and low-overhead technique to secure programs against integer overflows

The integer primitive type has upper and lower bounds in many programming languages, including C, and Java. These limits might lead programs that manipulate large integer numbers to produce unexpected results due to overflows. There exists a plethora of works that instrument programs to track the occurrence of these overflows. In this paper we present an algorithm that uses static range analysis to avoid this instrumentation whenever possible. Our range analysis contains novel techniques, such as a notion of “future” bounds to handle comparisons between variables. We have used this algorithm to avoid some checks created by a dynamic instrumentation library that we have implemented in LLVM. This framework has been used to detect overflows in hundreds of C/C++ programs. As a testimony of its effectiveness, our range analysis has been able to avoid 25% of all the overflow checks necessary to secure the C programs in the LLVM test suite. This optimization has reduced the runtime overhead of instrumentation by 50%.
The IOPT-Flow framework pairing Petri nets and data-flows for embedded controller development

The IOPT-Flow modeling framework is a Web-based set of tools for the design of embedded and cyber-physical system controllers, comprehending a graphical editor, a simulator and automatic code generation tools. Models are designed using an hybrid formalism combining Petri nets and data-flows to specify the reactive and data-driven parts of the controllers. Model composition based on components simplify the development of complex systems, that may be assembled with the help of a library of previously designed components. The synergy of the interaction between data-flow and Petri net elements brings many advantages to the design of mixed systems that must simultaneously perform data processing operations on input signals and manage complex event driven state-machines. The resulting controllers may be implemented on software or reconfigurable hardware devices, as the code generation tools support C and VHDL. The tools are free to use and are available online http://gres.uninova.pt/iopt-flow.
Analytical Evaluation of the Static MoM Terms for Volume and Surface Rectangular Domains

We present a simple analytical implementation of the static singular integrals arising in the volume/surface integral equation formulation for the analysis of mixed conducting and dielectric structures such as printed circuits with finite-size dielectric objects. The singularity of the Green's functions is extracted from the kernel of the integral equation as a static term. This term is then evaluated analytically for coincident rectangular cells in two and three dimensions. The new technique allows an accurate and efficient evaluation of method of moments (MoM) self-interactions compared to other methods previously used in the literature.
Multistage Model for Distribution Expansion Planning With Distributed Generation—Part I: Problem Formulation

This paper presents a model for use in the problem of multistage planning of energy distribution systems including distributed generation. The expansion model allows alternatives to be considered for increasing the capacity of existing substations, for installing new ones, for using distributed generation, and for the possible change to feeders in terms of addition and removing feeders sections; combining, subdividing, and load transfer between feeders; and replacement of conductors. The objective function to be minimized is the present value of total installation costs (feeders and substations), of operating and maintaining the network, and of distributed generation. The model takes operational constraints on equipment capacities and voltage limits together into account with logical constraints, aimed at reducing the search space.  an extension to the linear disjunctive formulation to represent the inclusion, exclusion, and replacement of branches and (2) a generalization of constraints related to the creation of new paths which can be applied in more complex topologies. The resulting mixed integer linear model allows the optimal solution to be found using mathematical programming methods, such as the branch-and-bound algorithm. The validity and efficiency of the model are demonstrated in Part II of this paper.
A differential inclusion algorithm for optimal control problems

The authors describe a conceptual algorithm allowing the computation of optimal control processes for control problems whose data are required to satisfy weak hypotheses on their control dependence. To achieve this goal, a differential inclusion formulation of the control problem is considered and a recursive procedure based on certain necessary conditions of optimality of the Pontryagin type is defined to compute a trajectory minimizing a given cost functional. State variable estimates are updated with information obtained by approximating a solution to the Hamiltonian inclusion of the optimality conditions. Under the hypotheses, this limiting trajectory is locally optimal for the given control problem and its associated control strategy is then computed. Since this procedure of searching for optimality involves only the state and adjoint variables, this algorithm is well suited to deal with the lack of regularity with respect to the control variable usually present in most control problems.<<ETX>>
Efficient novel IE analysis for inductive structures with obstacles attached to the waveguide walls

We present a novel efficient technique for the analysis of inductive structures containing metallic and dielectric obstacles, using a Surface Integral Equation (IE) formulation. Using the Surface Equivalence Principle, the main problem is divided into two subproblems. The first one is formulated with the parallel plate waveguide (PPW) Green's functions, and the second with the Green's functions of an unbounded homogeneous medium. The most important contribution of this paper is the consideration of obstacles attached to the waveguide walls. This situation requires a special treatment of the Green's functions of the second subproblem, by adding a spatial image with respect to the corresponding wall where the attachment is placed. This is essential in order to obtain adequate results, as it will be shown in further examples. Moreover, the presence of inductive dielectric posts connected to the walls inside cavity filters allows to obtain interesting elliptic responses, in addition to the possibility of reducing the multipactor risk for space applications.
A hybrid feedback control system for a nonholonomic car-like vehicle

This paper addresses the design of a hybrid feedback control system enabling a car-like, rectangular vehicle to perform a tight L-shaped turn manoeuvre. This case constitutes an effort towards the definition of a general purpose methodology for hybrid feedback control synthesis. The design effort encompasses the synthesis of a set of modalities and mechanisms to detect relevant events enabling the overall motion coordination so that a global goal is attempted. Simulations of the implemented controller have shown a strong robustness with respect to modeling uncertainty and execution errors.
The Computer for the 21st Century: Security & Privacy Challenges after 25 Years

Decades went by since Mark Weiser published his influential work on how a computer of the 21st century would look like. Over the years, some of the UbiComp features presented in that paper have been gradually adopted by industry players in the technology market. While this technological evolution resulted in many benefits to our society, it has also posed, along the way, countless challenges that we have yet to surpass. In this paper, we address major challenges from two areas that most afflict the UbiComp revolution: security and privacy. We examine open problems on software protection, long-term security, cryptography engineering, and privacy implications. We also point out promising directions towards the solutions of those problems. We claim that if we get all this right, we will turn the science fiction of UbiComp into science fact.
Perceptually driven coefficients pruning and quantization for the H.264/A VC standard

The increasing production and delivery of video contents in higher spatio-temporal resolutions is currently demanding for higher compression efficiency, notably beyond the state-of-art H.264/A VC video coding standard. Since the human viewers are always the last quality judge, the compression efficiency can be improved by exploiting the properties of the human visual system. This paper studies the integration of two perceptual coding tools, namely coefficient pruning and perceptual quantization step adjustment, in a H.264/A VC compliant video codec architecture. The obtained perceptually driven video codec allows reducing the coding rate up to 35% for the same visual quality in comparison with the reference H.264/A VC standard.
Joint Rate Control Algorithm for Low-Delay MPEG-4 Object-Based Video Encoding

This paper proposes an improved rate control algorithm for jointly encoding multiple arbitrarily shaped video objects in the context of low-delay MPEG-4 compliant video coding. The algorithm provides adequate mechanisms for dealing with deviations between the ideal and the actual behavior of video scene encoders, notably: 1) compensation mechanisms (e.g., rate control decisions) that are able to track these deviations and compensate them to allow a stable and efficient operation of the encoder, and 2) adaptation mechanisms (e.g., estimation of model parameters) that are able to instantaneously represent the actual behavior of the encoder and its rate controller. The proposed solution efficiently allocates the available resources, i.e., target bit rate and bitstream buffer space, aiming at maximizing the average scene quality and minimizing quality fluctuations along time and among the various video objects. The results show that this solution outperforms the usual reference solutions, notably those specified in the rate control informative annex of the MPEG-4 visual standard.
Robust repetitive control with saturating actuators: a LMI approach

This paper addresses the problem of tracking and rejection of periodic signals for uncertain linear systems subject to control saturation. To ensure the periodic tracking/rejection, a modified state-space repetitive control structure is considered. From this structure, conditions in a “quasi” LMI form are proposed to simultaneously compute a stabilizing state feedback gain and an anti-windup gain. Provided that the references and disturbances belong to a certain admissible set, these gains guarantee that the trajectories of the closed-loop system starting in a certain invariant ellipsoidal set contract to the linearity region of the closed-loop system, where the presence of the repetitive controller ensures the periodic tracking/rejection. Based on these conditions, an optimization problem aiming at the maximization of the invariant set of admissible states and/or the maximization of the set of admissible references/disturbances is proposed.
Robust control design of multiple resonant controllers applied to three-phase UPS inverter under unbalanced and nonlinear loads

This paper investigates the control of a four-wire three-phase Uninterruptible Power Supply (UPS) inverter using the internal model principle by applying multiple resonant controllers in the stationary abc-frame for zero-error tracking of sinusoidal reference and harmonic disturbances rejection due to nonlinear and unbalanced loads. The synthesis of such controllers is accomplished in a robust control framework where the controller parameters are determined by means of a convex optimization problem subject to a set of Linear Matrix Inequality (LMI) constraints. Simulation results from a 15.0-kVA UPS inverter are considered to illustrate and validate the performance and behavior of the controller design under nonlinear and unbalanced loads.
New improved version of J1…J4 interferometry method and its application to nanometric vibration measurements

Piezoelectric ceramics, such as PZT, can generate subnanometric displacements, but in order to generate multi-micrometric displacements, they should be either driven by high electric voltages (hundreds of volts), or operate at a mechanical resonant frequency (in narrow band), or have large dimensions (tens of centimeters). A piezoelectric flextensional actuator (PFA) is a device with small dimensions that can be driven by reduced voltages and can operate in the nano- and micro scales. Interferometric techniques are very adequate for the characterization of these devices, because there is no mechanical contact in the measurement process, and it has high sensitivity, bandwidth and dynamic range. A low cost open-loop homodyne Michelson interferometer is utilized in this work to experimentally detect the nanovibrations of PFAs, based on the spectral analysis of the interferometric signal. By employing the well known J1...J4 phase demodulation method, a new and improved version is proposed, which presents the following characteristics: is direct, self-consistent, is immune to fading, and does not present phase ambiguity problems. The proposed method has resolution that is similar to the modified J1...J4 method (0.18 rad); however, differently from the former, its dynamic range is 20% larger, does not demand Bessel functions algebraic sign correction algorithms and there are no singularities when the static phase shift between the interferometer arms is equal to an integer multiple of π/2 rad. Electronic noise and random phase drifts due to ambient perturbations are taken into account in the analysis of the method. The PFA nanopositioner characterization was based on the analysis of linearity between the applied voltage and the resulting displacement, on the displacement frequency response and determination of main resonance frequencies.
Radar cross section computation of multi-layered dielectric and magnetic obstacles using an efficient wavelet-like method

The scattering behaviour of multi-layered dielectric and magnetic obstacles is a complex problem of great practical interest. The bistatic radar cross section (RCS) of two dimensional scatterers composed of lossy magnetic and dielectric materials, including perfect conductor metals (PEC), is obtained following a surface formulation, the method of moments (MoM) and a wavelet-like matrix compression technique.
The IST-EURECOM Light Field Face Database

Light field cameras are emerging as powerful devices to capture rich scene representations that provide unique advantages for analysis and representation purposes. Some recent works have shown the power and usefulness of the richer information carried out by light field imaging, notably for face recognition. However, it is still difficult to fully assess how face recognition technology can benefit from these novel imaging sensors, notably due to the lack of appropriate test material. To support face recognition research exploiting light field images, the IST-EURECOM Light Field Face Database (IST-EURECOM LFFD) is presented in this paper. The purpose is to report the public availability of a light field face database which should be instrumental for designing, testing and validating light field imaging based recognition systems. The proposed face database includes data from 100 subjects, captured by a Lytro ILLUM camera in two 1–6 months separated sessions, with 20 samples per each person per session. To simulate multiple scenarios, the images are captured with several facial variations, covering a range of emotions, actions, poses, illuminations, and occlusions. The database includes the raw light field images, 2D rendered images and associated depth maps, along with a rich set of metadata. The IST-EURECOM LFFD is expected to become a valuable addition to existing face database repositories.
Probability updating for decoder and encoder rate control turbo based Wyner-Ziv video coding

In Wyner-Ziv video coding (WZVC), powerful error correcting codes must be used to achieve high compression efficiency; turbo codes are the most commonly used error correcting codes in WZVC. To improve the turbo coding performance in the context of WZVC, this paper proposes a probability updating technique (PUT) acting as an outer loop of the common turbo decoding operation. Whenever a turbo decoded bitplane is not error-free, the proposed technique attempts to correct bitplane errors by updating the correlation noise probabilities for the most likely in error bits, followed by turbo redecoding. The new tool is evaluated both in the context of encoder rate control (ERC) and decoder rate control (DRC) turbo based WZVC scenarios with average overall PSNR gains up to about 0.5 dB in ERC and average WZ rate savings up to about 6% in DRC.
Evaluating MPEG-4 video decoding complexity

When using the MPEG-4 standard, the several video objects composing a scene may vary in size along time and may be encoded at different temporal rates using different macroblock (MB) coding types. To limit the decoding complexity of the corresponding bitstreams, it is then necessary to put some limits on the variability of the number and type of MB as well as on the bitrate and on the picture memory required to store the decoded data. This paper evaluates the decoding complexity of the several MB types used in MPEG-4 video coding, by using statistics of the MB decoding times obtained with an optimized MPEG-4 video decoder. Based on these statistics, this paper proposes a set of relative complexity weights for the relevant MB complex classes, which can be used to improve on the MPEG-4 video complexity verifier (VCV) model.
Ear recognition in a light field imaging framework: a new perspective

Ear recognition is an emerging research area in image-based biometrics. The commercial availability of lenslet light field cameras able to capture full spatio-angular information has brought momentum to biometric and forensic research exploiting this new type of imaging sensors. This study is the first to consider the usage of light field cameras for ear recognition, proposing both an appropriate content database and an ear recognition solution. The novel Lenslet Light Field Ear DataBase (LLFEDB) includes 536 light field images corresponding to four different poses, from 67 subjects, captured with a Lytro ILLUM lenslet light field camera. The LLFEDB includes critical cases such as ear images partly occluded by ear piercing, earing, hair and combination of occlusions. The novel light field-based ear recognition solution proposed exploits the richer spatio-angular information available in the light field images. A comparative performance evaluation study using the LLFEDB, and focusing on the most recent light field and non-light field based descriptors for ear recognition, shows a very promising performance of the proposed descriptor, outperforming all the assessed descriptors.