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Recycled paper is extensively used worldwide. In the last decades, its market has expanded considerably. The increasing use of recycled paper in papermaking has led to the production of paper containing several types of impurities. Consequently, wastepaper mills are forced to implement quality control schemes for evaluating the incoming wastepaper stock, thus guarantying the specifications of the final product. The main objective of this work is to present a fast and reliable system for identifying different paper types. Therefore, undesirable paper types can be refused, improving the performance of the paper machine and the final quality of the paper manufactured. For this purpose, two fast techniques, i.e., Fourier transform midinfrared (FTIR) and reflectance near infrared (NIR), were applied to acquire the infrared spectra of the paper samples. Next, four processing multivariate methods, i.e., principal component analysis, canonical variate analysis (CVA), extended CVA (ECVA), and support vector machines (SVMs), were employed in the feature-extraction or dimension-reduction stage. Afterward, the k nearest neighbor (kNN) algorithm was used in the classification phase. Experimental results show the usefulness of the proposed methodology and the potential of both FTIR and NIR spectroscopic methods. Using the FTIR spectrum in association with SVM and kNN, the system achieved a maximum classification accuracy of 100%, whereas using the NIR spectrum in association with ECVA or SVM and kNN, the system achieved a maximum classification accuracy of 96.4%. [ABSTRACT FROM PUBLISHER]

A new biodegradable dielectric fluid for transformers, palm fatty acid ester (PFAE), with better cooling performance and oxidation stability than conventional mineral oil (MO) was developed in 2008. The aging of thermally upgraded paper (TUP) in PFAE was evaluated, comparing to MO and natural ester (FR3). The electrical properties of aged dielectric fluids were compared. Sealed aging SUS tanks containing copper, silicon steel, TUP, and PFAE, MO and FR3 (partly) in a nitrogen environment were aged at 130 °C-170°C for 20-120 days, with low concentrations of oxygen and moisture strictly controlled. Paper degradation after aging was determined using the degree of polymerization measurements. The gas production characteristics during the aging process were also compared. The results show that the TUPs in PFAE age at slower rates than those in MO, while at faster rates than those in FR3. Under the possibly low initial concentration of oxygen and water in the fluids in the absence of other material which may produce water during aging process, the limit service temperature for TUP in MO and PFAE with expected 30-year lifetime (DP450) would possibly reach 109°C and 113°C, respectively. Life estimation results show that the lifetime of the TUP in PFAE aging at 110°C would be at least 1.6 times the lifetime of the TUP in MO, if DP450 was set as the end-of-life point of the TUP. Aged PFAE exhibits highest breakdown voltage among the three types of dielectric fluid. Much lower acid value of aged PFAE than FR3 reveals that PFAE has better hydrolytic stability, which could ensure the safe operation of transformers. The aging mechanism is proposed. [ABSTRACT FROM PUBLISHER]

The presence of condensate inside the dryer cylinders results in a significant increase in the power and torque required until the condensate transitions to the rimming stage. This paper evaluates the effect of the condensate during the starting of a dryer section using the experimental curves reported by several authors, as well as a dimensionless model of the input power as a function of the condensate quantity and roll velocity. Through the evaluation of a nine-cylinder dryer section for various condensate quantities and varying number of cylinders containing condensate, a comparison is made to the power requirements of several actual paper machine dryer sections undergoing various starting procedures. These comparisons indicate that if the percent condensate (\condensate volume/full cylinder volume \times 100) in the range of 0.5%–1%, or greater, is nominally assumed to be present, then the sizing of the section drive capacity must take into consideration the additional indrive load resulting from this condensate. Options are proposed to consider the effect of the condensate without increasing the Technical Association of the Pulp and Paper Industry recommended drive capacity of dryer sections. [ABSTRACT FROM PUBLISHER]

The properties of insulation paper immersed in ageing-retardant oil and mineral oil were studied through a 264 days ageing experiment. Measurements of the color of the oil, the furfural concentration in the oil, water concentration, the degree of polymerization, and the acid concentration in the paper were performed. The results show that the ageing-retardant oil cannot only resist the oxidation of the oil itself, but also the ageing of the paper immersed within. The relevant inhibition mechanisms were studied. This paper demonstrates the ageing-retardant oil is capable of bounding water molecules. In addition, the esterification, which can resist the hydrolysis of the insulation paper, was studied through infrared spectrum analysis. Furthermore, this paper proposes that the combination of esterification and the hydrogen bonds will contribute to the anti-ageing ability. [ABSTRACT FROM PUBLISHER]

Many modern navigation systems and map-based services do not only provide the fastest route from a source location $s$ s to a target location $t$ t but also provide a few alternative routes to the users as more options to choose from. Consequently, computing alternative paths has received significant research attention. However, it is unclear which of the existing approaches generates alternative routes of better quality because the quality of these alternatives is mostly subjective. Motivated by this, in this paper, we present a user study conducted on the road networks of Melbourne, Dhaka and Copenhagen that compares the quality (as perceived by the users) of the alternative routes generated by four of the most popular existing approaches including the routes provided by Google Maps. We also present a web-based demo system that can be accessed using any internet-enabled device and allows users to see the alternative routes generated by the four approaches for any pair of selected source and target. We report the average ratings received by the four approaches and our statistical analysis shows that there is no credible evidence that the four approaches receive different ratings on average. We also discuss the limitations of this user study and recommend the readers to interpret these results with caution because certain factors may have affected the participants’ ratings. [ABSTRACT FROM AUTHOR]

Availability of a common, shared benchmark to provide repeatable, quantifiable, and comparable results is an added value for any scientific community. International consortia provide benchmarks in a wide range of domains, being normally used by industry, vendors, and researchers for evaluating their software products. In this regard, a benchmark of untimed Petri net models was developed to be used in a yearly software competition driven by the Petri net community. However, to the best of our knowledge there is not a similar benchmark to evaluate solution techniques for Petri nets with timing extensions. In this paper, we propose an evaluation framework for the comparative analysis of generalized stochastic Petri nets (GSPNs) simulation techniques. Although we focus on simulation techniques, our framework provides a baseline for a comparative analysis of different GSPN solvers (e.g., simulators, numerical solvers, or other techniques). The evaluation framework encompasses a set of 50 GSPN models including test cases and case studies from the literature, and a set of evaluation guidelines for the comparative analysis. In order to show the applicability of the proposed framework, we carry out a comparative analysis of steady-state simulators implemented in three academic software tools, namely, GreatSPN, PeabraiN, and TimeNET. The results allow us to validate the trustfulness of these academic software tools, as well as to point out potential problems and algorithmic optimization opportunities. [ABSTRACT FROM AUTHOR]

This paper analyzes the unsymmetrical operation of the dc/dc MMC caused by parametric uncertainty. The unsymmetrical operation is referred to as the condition in which parameters involved in ac power generation are not equal in the phase-legs of the converter. Because existing models in the literature cannot exhibit the unsymmetrical operation of the dc/dc MMC, new detailed and simplified steady-state models are developed in this paper. In the developed models, the connection between the operation of different phase-legs shows itself when the dc-link impedance is considered. Using the developed models, the parameters that can force the converter to operate in unsymmetrical conditions are identified, and the maximum variation that the converter can tolerate is found. It is shown that even a small parameter variation leads to the leakage of the ac circulating current into the dc-link, which is not acceptable. By conducting various case studies, the impacts of the dc-link length, the transmitted power, and the conversion ratio on the unsymmetrical operation of the dc/dc MMC are characterized. The results showed that the converter would be more sensitive to the parameter variation as these parameters increase. Comparative analysis and simulation results confirm the validity and effectiveness of the presented models and analysis method. [ABSTRACT FROM AUTHOR]

In this paper, a circulating-current-excited switched reluctance generator system with the diode rectifier is comparatively studied with a field-current-separated switched reluctance generator. By using a DC power source connected in series with the winding to provide the circulating current, a controllable excitation field is established in the proposed generator. To highlight the influence of this DC voltage source, the injected field current of the field-current-separated generator is kept the same as the circulating current of the circulating-current-excited generator. Then, both advantages and disadvantages of the generators are summarized. The circulating-current-excited switched reluctance generator system inherits both the advantages of good reliability of the separated-winding generator by using the diode rectifier and low copper loss of the integrated-winding machine by combining the AC and DC current in one set of windings. Furthermore, two more practically conventional field-current-separated generators are also compared with the proposed generator in terms of the external characteristics. These two conventional generators have different winding configurations. At last, the analysis is verified by experiments. [ABSTRACT FROM AUTHOR]

For modular permanent magnet (PM) machines with overlapping (OLP) windings widely employed in wind power generation, the large torque ripple and long end winding are major issues. In order to solve these problems, PM machines with non-overlapping (NOLP) windings and redundant teeth for easy modularity are proposed in this paper. The comparative study between modular machines with these two kinds of windings is necessary and is the major focus of this paper. For the sake of clarity, two modular dual 3-phase machines with 42-slots/32-poles (42S/32P) and 192S/32P combinations are chosen as examples to show the differences in terms of machine performance. The proposed 42S/32P modular machine adopts NOLP winding, while the conventional 192S/32P one uses the OLP type. Based on the results, it is found that the modular machine with NOLP winding has comparable average torque and efficiency. In the meantime, much lower torque ripple exists for the proposed modular machine regardless of the current value. The shorter and simpler end windings are beneficial to manufacturability. Moreover, the proposed modular machine with NOLP winding will be more fault tolerant due to smaller mutual inductances between phases and larger d-axis inductance. Finally, the proposed 42S/32P modular machine is prototyped and the experiments validate the correctness of the analyses in this paper. Despite two specific examples being used, the conclusion should be generic and can be employed to modular machines with other slot and pole number combinations. [ABSTRACT FROM AUTHOR]

In this paper, two novel double-sided hybrid-excitation flux-reversal linear motors (DSHEFRLM) with the surface (S-) and interior (I-) permanent-magnet(PM) arrangements are proposed and comparatively investigated. The proposed motors feature an asymmetrical double-sided primary configuration which enables the armature and field excitations to be placed separately. Through 2-D finite-element method (FEM), two motor structures with different slot/pole combinations are optimized, and then, the magnetic fields and electromagnetic performances are calculated, including inductances, no-load flux linkage, thrust characteristics, and PM demagnetization capability. By comparison, it is found that S-DSHEFRLMs show larger thrust density while I-DSHEFRLMs exhibit superior flux-adjusting capability. Finally, these predicted results are validated by 3-D FEM. [ABSTRACT FROM AUTHOR]

This paper presents several different control structures that facilitate flight control and does a comparison between them. Specifically, this paper considers command-filtered backstepping, nonlinear dynamic inversion (NDI), and a new decoupled approach that decouples the rotational and translational dynamics by estimating the higher order derivatives of the angle of attack and sideslip angle. The latter is also augmented by exploiting a feedback of the control deficiency resulting in improved performance. A series of simulations is performed to gage the performance of different controllers, showing the performance in the case of sensor noise, when performing aggressive maneuvers, when exposed to wind disturbances, as well as when there are model imperfections. The main finding is that all control structures work well for flight control, but the new decoupled method is able to improve the performance. A major reason for the improvement is that the decoupling method alleviates the tuning of the control gains, thus allowing for faster response through suitable gains. [ABSTRACT FROM AUTHOR]

Thermal microelectromechanical system (MEMS) devices have gained immensely in popularity due to their good performances, relatively simple fabrication process, and to the availability of modeling tools. In this paper, the modeling results of several models were compared and the ability of each to reliably assess the performances of V-shaped thermal MEMS devices was investigated. The results of several models, in which the governing equations of motion were directly solved, were compared to those obtained from nonlinear large-deflection 3-D finite element analysis that was verified experimentally. The models were modified by including the temperature-dependent properties of the material of the device. In addition, a numerical iterative force control solution scheme was developed and used to predict the performances of V-shaped devices. Important parameters of V-shaped devices, such as apex deflection, stiffness, and output force, were evaluated in terms of the applied temperature and device geometry. In addition, the feasibility of capacitive sensing was demonstrated and high signal-to-noise ratio was calculated. Finally, the influence of microfabrication tolerances and internal stress on the performances of the devices were studied. Therefore, this paper will help future researchers and designers to assess the reliability of models of thermal MEMS devices and better evaluate device performance. [ABSTRACT FROM AUTHOR]

A variable reluctance electric machine with a two-degree of freedom rotor motion characterized by rotation around the center of the rotor and orbiting around the center of the stator is studied. One motivation for adopting such rotor motion would be to allow torque generation through both the radial and tangential components of the electromagnetic forces created in the airgap, as opposed to common rotary machines in which torque is a byproduct of only the tangential component of the airgap electromagnetic forces. Furthermore, the rotor motion provides a built-in gearing action similar to that of a cycloidal drive, which allows natural torque multiplication and the tight integration of the electromagnetic and mechanical systems. The two-degree of freedom rotor motion also results in a counter-intuitive inertia characteristic of this machine concept which is elaborated in this paper for the first time. Due to the reluctance nature of the torque, and because of the distinctive rotor motion profile which resembles the motion of a cycloid, the studied machine is called a cycloidal reluctance (CR) electric machine (CRM). In this paper, the principle of operation of the CRM is explained, and its performance is compared to a counterpart switched reluctance machine (SRM). A prototype is built, and the theoretical torque calculations are validated by experimental measurements. [ABSTRACT FROM AUTHOR]

This paper presents a new type electromagnetic lead screw (EMLS) intended for wave energy application. Similar to the mechanical lead screw, this electromagnetic version can transfer slow linear motion to high-rotational motion, offering gearing effects. Compared with the existing pure magnetic lead screw (MLS) employing permanent magnets only, the new EMLS proposed uses dc current to provide the required helical-shape magnetic field, offering a much simpler, robust structure compared with the MLS. The working principle and the performances of this EMLS are analyzed in this paper. Comparison with PM-type lead screw is given. In addition to this, the theoretical analysis to support the use of a 2-D finite element model to analyze the 3-D magnetic-type lead screw is given, which has not been well covered in the existing literature. [ABSTRACT FROM AUTHOR]

The objective of this paper is to review various methods of determining the extent of hazardous areas in industrial facilities where explosive gas or vapor atmospheres may be present. Three different approaches are analyzed and compared. The first one is recommended in North American Standards, such as API 500, API 505, and NFPA 497. The second is one of the proposals for the second edition of the International Standard IEC 60079-10-1 (adopted as European standard EN 60079-10-1). The third approach had been previously worked out with the authors' contribution and had been adopted by the Italian Guide CEI 31-35 since 2001. The last two approaches are analytical, meanwhile the first one is prescriptive. In the second part of this paper, both analytical approaches are applied to the releases which are analyzed in NFPA 497 as practical examples. Resulting hazardous area extents are compared, and the differences among the three methods are discussed. [ABSTRACT FROM PUBLISHER]

The paper aims at defining a methodology to evaluate the lightning performance of a system of overhead distribution lines. As is well known, the evaluation of the lightning performance relies generally on a Monte Carlo approach that generates many different lightning events and calculates the corresponding overvoltages. To perform such calculation, the power system computer aided design (PSCAD) module developed in the companion paper is adopted. However, as any call to PSCAD implies a nonnegligible computational effort, here an efficient approach is presented in order to limit the number of simulations as much as possible. The obtained results are compared with the ones provided by other available techniques both on simple structures in order to highlight the main features of the method and on a typical Italian distribution network segment. The comparative analysis shows good agreement between the methods and the effectiveness of the proposed technique in terms of computational effort reduction. [ABSTRACT FROM PUBLISHER]

This paper presents a new algorithm, called steady-state and generational evolutionary algorithm, which combines the fast and steadily tracking ability of steady-state algorithms and good diversity preservation of generational algorithms, for handling dynamic multiobjective optimization. Unlike most existing approaches for dynamic multiobjective optimization, the proposed algorithm detects environmental changes and responds to them in a steady-state manner. If a change is detected, it reuses a portion of outdated solutions with good distribution and relocates a number of solutions close to the new Pareto front based on the information collected from previous environments and the new environment. This way, the algorithm can quickly adapt to changing environments and thus is expected to provide a good tracking ability. The proposed algorithm is tested on a number of bi- and three-objective benchmark problems with different dynamic characteristics and difficulties. Experimental results show that the proposed algorithm is very competitive for dynamic multiobjective optimization in comparison with state-of-the-art methods. [ABSTRACT FROM PUBLISHER]

This paper presents the comparative analysis of the characteristic features of two 4/2 switched reluctance motors (SRMs) designed for a very high-speed drive. The use of two-phase construction of SRM with irregular air-step gap makes it possible to achieve the required parameters of the drive. The analysis presents the comparison of two distinct structures designed for the same very high-speed drive. In this paper, a novel mathematical model that takes into account the nonlinearity of the magnetic circuit is presented. The results of numerical calculations and laboratory tests of the influence of the possible use of an anisotropic magnetic material in the rotor magnetic circuit are presented. The influence of control parameters on the motor properties is specified. Both the structures were compared with the respect to employed electric parameters. It is important for high-speed structures that a maximal speed of the motor should not affect permissible parameters of the rotor in a negative way. The high-speed structures should be properly designed to ensure a safety margin. The selected laboratory test results that show electric parameters are presented following the specification of the first critical speed based on the Campbell diagram, the maximum speed limited by allowable stresses. It was shown that both the structures analyzed fulfill the condition of a safety margin. A number of thermal problems of the structures analyzed are discussed. The design assumptions related to the possibility of using a higher current density in the motor windings were verified under laboratory conditions. [ABSTRACT FROM AUTHOR]

In this paper, the partitioned stator (PS) structure is extended to variable-flux memory machines, forming two newly emerged PS switched-flux memory machines (PS-SFMMs) with series and parallel hybrid magnet configurations. From the perspective of geometry, both two PS-SFMMs share identical outer stator and rotor segments, while two different types of permanent magnet (PM) arrangements are employed in the inner stationary part. Thus, the developed machines can inherent the geometric separation of the armature winding and PM excitations from the PS design, thus achieving acceptable torque capability, and excellent air-gap flux control. A comparative study between PS-SFMMs with series and parallel structures is established. First, the topologies and operating principle are introduced, respectively. In addition, the design tradeoffs and PM sizing of the two PS machines are revealed and optimized with a simplified magnetic circuit model. Then, the electromagnetic characteristics of PS-SFMMs with different magnetic circuits are investigated and compared with the finite-element (FE) method. The FE results are validated by the experiments on a parallel prototype. [ABSTRACT FROM AUTHOR]

Compared with a ferrofluid (FF) seal used as a sealing material, magnetorheological (MR) fluid has higher sealing pressure at the same condition. This is because MR fluid not only has magnetic property but also shows obviously elasto-plastic performance, which differs from FFs, under the magnetic field. On this basis, this paper analyzed, respectively, the static seal performance of MR fluids and FFs based on their magnetic properties through experimental and numerical studies. The results showed that an obvious pressure drop happened when the pressure is about 400 kPa in seal cavity for MR fluid seal, but the pressure was quickly down to around 390 kPa; nevertheless, the maximum pressure of the FF seal is 200 kPa, and the seal time with leak-free is about 2.5 min, and then the value quickly goes down to zero. The maximum pressure of every pole tooth of FF seal is about 11.11 kPa. The pressure of MR fluid seal is 21.67 kPa when there is a significant decrease during pressuring, and the maximum pressure of every pole tooth of MR fluid seal is 41.37 kPa. At last, the relationship of the sealing pressure of MR fluid seal with the time was derived. [ABSTRACT FROM AUTHOR]

This paper presents the performance comparison between a flux concentration (FC) and triple-permanent magnet (PM) consequent pole (CP) magnetic gear (MG) rotor typology with the same 7.5:1 gear ratio. The triple PM CP MG is unique in that it can create torque change through two field heterodyning pole combinations. The performance with respect to volumetric and mass torque density is considered. It is shown that the FC typology can operate with a higher mass and volumetric torque density, even when using a low FC ratio rotor. [ABSTRACT FROM AUTHOR]

In this paper, the torque production mechanisms of flux-reversal permanent magnet (FRPM) machine and Vernier permanent magnet (PM) machine are analyzed and compared based on air-gap field modulation. Working harmonics of PM magnetomotive force (MMF) and air-gap permeance in two machines are analytically identified and compared, indicating that the fundamental PM MMF together with all permeance harmonics contribute to the torque production of Vernier machine whereas all PM MMF harmonics but only fundamental permeance in FRPM machine produces the torque. Thanks to the utilized large dc component of air-gap permeance, the torque density of Vernier machine is revealed to be better. Influence of critical parameters on machine performance, such as PM thickness and slot width ratio of the modulation pole, is also investigated. It shows that FRPM machine is more sensitive to the design parameters. Both finite-element analysis and experimental validation are conducted to verify the conclusion. [ABSTRACT FROM AUTHOR]

The growing demands for improved fire safety, source material sustainability, environment friendliness, and asset life extension have driven the research and development efforts of synthetic esters, less-flammable fluids. However the relatively limited number of work on these esters and their cost still limit their uses to specific applications. This contribution reports some investigations onto the Electrostatic Charging Tendency (ECT) of a commercially available ester fluid. Comparison is made with mineral oil, as this is a fluid we are familiar with. Fresh (unaged) and aged fluid samples were investigated in a spinning disk system under laboratory controlled conditions. Changes in static electrification were compared to some aging indexes (interfacial tension, turbidity, relative dissolved decay products). This contribution is not only intended to provide a fresh review in this domain of research, but also contains a substantial amount of new material with a view of closing some gaps in the present state of knowledge of oil streaming electrification. The obtained results show that static electrification currents are affected by fluid motion velocity, type of paper, moisture content and the aging byproducts. It was also found that the removal of dissolved oxygen by nitrogen blanketing contributed to the reduction in static electrification. [ABSTRACT FROM AUTHOR]

This paper extends the analysis of the companion paper by presenting a comparative analysis of the impact of interface traps on the I-V characteristics of InAs nanowire tunnel FETs or MOSFETs with a spatially random distribution of traps. The physical mechanisms behind the effects of traps in either tunnel FETs or MOSFETs are compared and, furthermore, traps are also investigated as a possible source of device variability. Our results show that, in MOSFETs, an aggressive oxide thickness scaling can effectively counteract the degradation of the subthreshold slope (SS) possibly produced by interface traps. Tunnel FETs are instead more vulnerable to traps, which are probably the main hindrance to the experimental realization of tunnel FETs with an SS better than 60 mV/decade. [ABSTRACT FROM AUTHOR]

In this paper, a detailed qualitative & quantitative comparative analysis of measurement based centralized voltage stability monitoring approaches using Thevenin equivalent is presented. These methods typically utilize the state estimation output, making them easily implementable at the control centers. The metrics for comparison are defined in terms of computation resources required, accuracy of identifying the critical loading point, critical contingency screening, and robustness to noise. These performance metrics are relevant for practical implementation and are presented on the IEEE 300 bus system and the MATPOWER 2383-bus system. To the best of our knowledge, this is the first systematic qualitative & quantitative comparison between various measurement based voltage stability methods using these performance metrics. The results will guide the utilities and operators about possible trade-offs between the various methods for large systems, enabling them to make an informed decision on the specific method to use for their needs. [ABSTRACT FROM AUTHOR]

In many papers, random modulation of power electronic converters is described as an electromagnetic interference (EMI) mitigation technique, which contributes to the assurance of electromagnetic compatibility (EMC) of systems consisting of power electronic converters and serial transmission-based control and measuring devices. However, experimental results as well as theoretical analyses of physical phenomenon suggest that the EMI reduction is ostensible and results from the measuring procedure adopted in standards. This article presents the first known approach to compare the influence of deterministic and random modulation of transmission errors rate in serial communication systems. The comparison is based on the especially developed mathematical models, which are validated experimentally, using a simple setup with a dc/dc converter injecting a noise into the USB/RS232 converter representing a serial transmission scheme. The comparison reveals that for the studied switching frequency range from 10 kHz to 1 MHz, on average, there is no significant difference between random and deterministic modulations with respect to the probability of error rate in serial communication systems. Thus, in such systems, random modulation should not be considered as a valid EMC-assuring technique. [ABSTRACT FROM AUTHOR]

Faced with massive data, subsampling is a commonly used technique to improve computational efficiency, and using nonuniform subsampling probabilities is an effective approach to improve estimation efficiency. For computational efficiency, subsampling is often implemented with replacement or through Poisson subsampling. However, no rigorous investigation has been performed to study the difference between the two subsampling procedures such as their estimation efficiency and computational convenience. This paper performs a comparative study on these two different sampling procedures. In the context of maximizing a general target function, we first derive asymptotic distributions for estimators obtained from the two sampling procedures. The results show that the Poisson subsampling may have a higher estimation efficiency. Based on the asymptotic distributions for both subsampling with replacement and Poisson subsampling, we derive optimal subsampling probabilities that minimize the variance functions of the subsampling estimators. These subsampling probabilities further reveal the similarities and differences between subsampling with replacement and Poisson subsampling. The theoretical characterizations and comparisons on the two subsampling procedures provide guidance to select a more appropriate subsampling approach in practice. Furthermore, practically implementable algorithms are proposed based on the optimal structural results, which are evaluated through both theoretical and empirical analyses. [ABSTRACT FROM AUTHOR]

The multichannel generator is a kind of special generator, which is developed to enhance power reliability in safety critical applications. This paper compares the dynamic performance computation for a 12/8 dual-channel switched reluctance generator (DCSRG) under single- and dual-channel operation modes. First, the static phase self- and mutual inductances are numerically calculated through finite element analysis (FEA). Based on the magnetic characteristics, the mathematical and simulation models of DCSRG under different operation modes are presented. In the dual-channel model, the effect of mutual coupling between phases of each channel in the DCSRG is considered. By using these proposed dynamic models, the different performances for the DCSRG under single- and dual-channel operation modes, such as generating process under closed-loop control, steady-state performance at different conditions, sudden change in load operation, and the operating status when changing from motoring to generating, are predicted and compared. Finally, a 12/8 DCSRG system is built for experimentation. The simulation and experimental results are also compared in the DCSRG system under different operation modes to verify the proposed modeling and analysis. [ABSTRACT FROM AUTHOR]

This paper presents the results of a comparative analysis among three methods for attributing responsibilities of voltage unbalance in the electrical network, namely, the IEC, three-phase power flow, and conforming and nonconforming currents methods. To do this, computational and experimental simulations are carried out based on employing a system comprised of a perfectly transposed transmission line and two loads that are not always balanced. The cases selected for this study also permit the identification of the main advantages and disadvantages of each method under evaluation. This work is characterized as a topic of great interest to the regulatory agencies responsible for establishing regulations, and for utilities and consumers. It is relevant because by using the methods investigated in this paper, the identification of the sources, which generates unbalance, the division of responsibilities, and the application of penalties due to limit transgression will be possible. [ABSTRACT FROM AUTHOR]

Simulation is a valuable way to develop cleaner transportation systems. Nevertheless, the complexity of this kind of system leads to complex models, particularly when taking into account nonlinear aspects of traction power substations (TPSs). Thus, this paper proposes different TPS models based on energetic macroscopic representation. An appropriate model is deduced from comparisons between the different models to realize energetic studies. It is finally applied to the simulation of a simple subway line, which is experimentally validated. [ABSTRACT FROM AUTHOR]

The paper [1] reports on comparative experiments on a triggered-gap electrode used as an early streamer emission air terminal, with some equivalent circuit analysis of the triggering circuit and simplified electric field calculations. [ABSTRACT FROM PUBLISHER]

Multilevel inverters have created a new wave of interest in industry and research. While the classical topologies have proved to be a viable alternative in a wide range of high-power medium-voltage applications, there has been an active interest in the evolution of newer topologies. Reduction in overall part count as compared to the classical topologies has been an important objective in the recently introduced topologies. In this paper, some of the recently proposed multilevel inverter topologies with reduced power switch count are reviewed and analyzed. The paper will serve as an introduction and an update to these topologies, both in terms of the qualitative and quantitative parameters. Also, it takes into account the challenges which arise when an attempt is made to reduce the device count. Based on a detailed comparison of these topologies as presented in this paper, appropriate multilevel solution can be arrived at for a given application. [ABSTRACT FROM AUTHOR]

This paper describes and analyzes the extra-high-voltage double-circuit cable line between Sicily and Calabria which is a reinforcement of the Italian southern transmission grid. This is one of the longest ac submarine links in the world. The multiconductor cell analysis of this land–submarine double-circuit single-core cables has been compared with an electromagnetic transient program model with a very good agreement. The different choices of bonding systems implemented in the real Italian installation are theoretically justified by means of the two-software comparison. [ABSTRACT FROM AUTHOR]

The arguments presented in the above comments are refuted. The following are pointed out: 1) Veliadis' papers did not include the vertical-junction field-effect transistor (VJFET) dimensions required for readers to make technical analysis and comparison. 2) The current through the gate p-n junction of a VJFET is also affected by the ohmic contact and metal spreading resistance; therefore, the external gate terminal voltage alone does not determine whether a VJFET is operated in bipolar mode or not. 3) A longer vertical channel with a more invariant or uniform vertical-channel opening makes it much easier to realize higher performance and higher voltage normally-off JFETs because of the lower channel resistance and the larger drain voltage needed to punch through the drain-to-source barrier. [ABSTRACT FROM AUTHOR]

Energy conservation is essential to wireless networks, particularly for third-generation (3G) and fourth-generation (4G) wireless systems, because high-speed data transmissions would rapidly exhaust the energy of a mobile station. This paper presents the details of energy-saving mechanisms for packet data services in two major standards, namely, the Third-Generation Partnership Project (3GPP) and the Third-Generation Partnership Project 2 (3GPP2). In addition to qualitative comparison, analytic models and quantitative comparison based on the energy-saving models are provided. The proposed analytic models analyze and quantify the energy consumption for bursty and streaming traffic in cdma2000 and wideband code division multiple access (WCDMA). The impacts of an inactivity timer on energy consumption and reconnection cost are demonstrated further by simulation and analysis. The analytic results could be used to suggest proper timer lengths that can balance the energy consumption and the reconnection cost. In addition to providing insights of the energy- conservation mechanisms of 3GPP and 3GPP2, which are often difficult to directly obtain from standards specifications, results shown in this paper are also practical for 3GPP and 3GPP2 operators to determine proper parameters for energy efficiency. [ABSTRACT FROM AUTHOR]

This paper proposes a procedure and methodology for performance target setting related to continuity metrics in electricity distribution networks. This proposal deals with one of the key issues in the monopoly regulation, which is either the reduction of the information asymmetry among economic agents or the emulation of a competitive environment in industry segments usually considered as natural monopolies. This paper develops an approach toward standard definitions for Customer Average Interruption Duration Index (DEC) and Customer Average Interruption Frequency Index (FEC) based on inter-companies comparative analysis. This approach introduces productive efficiency concepts to the definition of network performance. In order to do so, the data envelopment analysis (DEA) technique, used for defining the efficiency frontier, was combined with the dynamic cluster technique, oriented toward models of identification of similar networks. A technique for comparative analysis was used for the definition of the network expected performance. Examples with the Brazilian electric systems are provided to clarify the methodology suggested by this paper. [ABSTRACT FROM AUTHOR]

This paper compares the experimental performance of three flux and speed observers for speed-sensorless induction motor drives and discusses the cause of their differences. The small signal analysis using the linearized model is carried out to analyze stability. Three methods are generally accepted to be representative candidates for high sensorless performance, namely: 1) rotor-flux model reference adaptive system (MRAS); 2) torque-current MRAS; and 3) adaptive nonlinear flux observer. Many other sensorless methods improved these methods. The paper discusses baseline conditions for the experiments and the stability analysis, which include matched load inertia, specified speed estimator dynamics, and sensorless operation within a speed control loop. For the comparison tests in the paper, the speed estimation dynamics of the methods are the same; this is important for parameter sensitivity. The paper concentrates on the low-speed performance, and all results shown are under sensorless speed control. [ABSTRACT FROM AUTHOR]

Meta-models proved to be a very efficient strategy for optimization of expensive black-box models, e.g., finite element simulation for electromagnetic devices. It enables to reduce the computational burden for optimization purposes. Kriging is a popular method to build meta-model. Its statistical properties were first used in efficient global optimization for unconstrained problems. Afterward, many extensions were introduced in the literature to deal with constrained optimization. This paper presents a comparative study of some infill criteria for constraints handling and a new strategy for parallelization of the expensive computations of models. TEAM workshop problem 22 is taken as an electromagnetic test problem. [ABSTRACT FROM AUTHOR]

Transcranial magnetic stimulation (TMS) is a non-invasive neuro-stimulation based on the principle of electromagnetic induction that uses brief, strong magnetic pulses of electric current delivered to a coil placed on the subject’s head to induce an electric field in the brain. This electric field could stimulate and modulate neural activity. Induced E-field inside brain generated by repetitive TMS (rTMS) can produce changes in neural activity that extends beyond the period of stimulation. Therefore, rTMS can be used as a probe for exploring higher brain functions and as potential treatment technique for psychiatric and neurological disorders. However, based on the chosen shape of the excitation coil, there exists a tradeoff between the excitation focality in the brain and the depth to which the field penetrates. In this paper, a new design of TMS coil is proposed to enhance the performance of the traditional figure-of-eight (FOE) coil. 3-D finite-element method has been used to simulate and compare the electric field induced inside the model of a human brain under the influence of both coil designs. An experimental verification was then followed to validate the advantages of the proposed coil design over the classic FOE coil. [ABSTRACT FROM AUTHOR]

An extensive investigation of fabricated AlGaN/GaN fin-shaped metal-insulator-semiconductor high-electron-mobility transistors (Fin-MISHEMTs) with Al2O3 dielectric is presented in this paper. Based on the pulsed I-V measurements and numerical simulation, the dynamic characteristics of GaN-based Fin-MISHEMTs were carried out under various quiescent bias conditions and temperatures. Moreover, the physical mechanisms of current collapse and dynamic on-resistance increase induced by trapping effects were analyzed. The results show that the observed nonmonotonic variation of current collapse with the gate quiescent bias voltage is resulted from the combination of gate leakage injection-related and hot-electron injection-related trapping effects. Compared with the conventional planar MISHEMTs, the current collapse of AlGaN/GaN Fin-MISHEMTs is smaller due to lower gate leakage and smaller threshold voltage shift, which is benefited from its enhanced gate controllability. The current collapse and dynamic on-resistance increase of Fin-MISHEMTs can be further suppressed by optimizing the device structure, such as designing the fin channels only under the gate. [ABSTRACT FROM AUTHOR]

Similar to the conventional three-phase parallel-connected MMC (PC-MMC), the three-phase series-connected MMC (SC-MMC) is a strong potential solution for high-voltage direct current (HVDC) applications. The study of SC-MMC focuses on the control strategy, neglecting its small-signal dynamics, not to mention its stability when interacting with the AC grid. Work on small-signal modeling of MMC is limited to parallel-connected configurations. SC-MMC differs from PC-MMC in structure and harmonic content; hence, it is necessary to establish an accurate model of SC-MMC according to its own characteristics. This paper introduces the circuit and control of SC-MMC and compares it with PC-MMC. Multi-harmonic linearization is used to establish the AC impedance model of SC-MMC over the whole control system, including the third harmonic suppression controller. We take a PC-MMC station of the Wudongde HVDC project as a benchmark to explore the potential application of SC-MMC when constructing new HVDC stations to extract power from an existing DC transmission corridor. The strengths and weaknesses of SC-MMC in HVDC applications are discussed, and it is compared to PC-MMC with regard to the impedance characteristic. [ABSTRACT FROM AUTHOR]

The rapid development of Convolutional Neural Networks (CNNs) in recent years has triggered significant breakthroughs in many machine learning (ML) applications. The ability to understand and compare various CNN models available is thus essential. The conventional approach with visualizing each model's quantitative features, such as classification accuracy and computational complexity, is not sufficient for a deeper understanding and comparison of the behaviors of different models. Moreover, most of the existing tools for assessing CNN behaviors only support comparison between two models and lack the flexibility of customizing the analysis tasks according to user needs. This paper presents a visual analytics system, VAC-CNN (Visual Analytics for Comparing CNNs), that supports the in-depth inspection of a single CNN model as well as comparative studies of two or more models. The ability to compare a larger number of (e.g., tens of) models especially distinguishes our system from previous ones. With a carefully designed model visualization and explaining support, VAC-CNN facilitates a highly interactive workflow that promptly presents both quantitative and qualitative information at each analysis stage. We demonstrate VAC-CNN's effectiveness for assisting novice ML practitioners in evaluating and comparing multiple CNN models through two use cases and one preliminary evaluation study using the image classification tasks on the ImageNet dataset. [ABSTRACT FROM AUTHOR]

A comparative study of new partitioned stator hybrid excitation axial flux switching permanent magnet (HEAFSPM) motors with different partitioned excitation stator topologies for in-wheel traction applications is presented in this paper. The realization approaches of the partitioned stator HEAFSPM motor are discussed, and the motor topology with windings and permanent magnets (PMs) separately setting on different stators is selected in view of the advantageous structure for thermal management. On this basis, two partitioned excitation stator topologies including C-type tooth core and T-type tooth core stator configuration are proposed, and the air-gap flux modulation and flux regulation principle of the motors are analyzed. In addition, the design method of the partitioned stator HEAFSPM motor considering the effect of hybrid excitation sources is provided, and the two motors with different tooth cores are designed respectively. Meanwhile, for a fair comparison, the multiple objectives optimization method coupled with the sensitivity analysis is employed to optimize the two motors. The electromagnetic performances, anti-demagnetization capability, and flux regulation performance of the two motors are all investigated in detail. Finally, two prototype motors are fabricated and tested. Both the theoretical analysis and experimental results verify the effectiveness and reasonability of the motor. [ABSTRACT FROM AUTHOR]

This paper presents a comparative investigation, design and development issues about six different single-stage topologies, applied as electronic ballasts, for electrodeless fluorescent lamps. The ballast is intended to feed a 100 W lamp at 250 kHz, with dimming feature. The proposed topologies use different converters for the power factor correction (PFC) stage: Buck-Boost, SEPIC, Zeta, Cúk, Flyback, and Boost. All of them operate in discontinuous conduction mode. A resonant half-bridge inverter is used as lamp power control (PC) stage. The integration of both stages (PFC and PC) is proposed in this paper. In this way, it is possible to reduce the number of active switches, as well as simplify the required driving and control circuitry. Experimental results demonstrate the feasibility of the proposed dimming technique that achieved around 56% lamp power dimming, from 100 W down to 44 W. The implemented topologies attained high average power factor (>0.98), and low line current average total harmonic distortion (<;15.3%). A comparison among all the proposed topologies in terms of power factor, harmonic distortion, efficiency and number of components is presented. Finally, a comparison between an integrated and a nonintegrated SEPIC half-bridge converter is also performed. [ABSTRACT FROM AUTHOR]

This paper presents a comparative study on different surrogate models for an application to multidimensional optimal design of electromagnetic devices. The surrogate model is combined with a heuristic optimization algorithm, which usually requires a lot of objective function calls. For this, various Kriging surrogate models, including dynamic Kriging (DK) and multiquadric radial basis function with optimal shape parameter, are investigated and discussed. In the DK surrogate model, the optimal combination of the basis functions is obtained using an improved binary particle swarm optimization algorithm. [ABSTRACT FROM PUBLISHER]

Energy saving in production plants is becoming more and more relevant due to the pressure from governments to contain the environmental impact of manufacturing and from companies to reduce costs. One of the measures for saving energy is the implementation of control strategies that reduce energy consumption during the machine idle periods. This paper proposes a framework that integrates different control policies for switching the machine off when production is not critical and on when the part flow has to be resumed. A general policy is formalized by modelling explicitly the energy consumed at each machine state. The policy parameters that minimize the requested machine expected energy are provided analytically for general distributions. Numerical results are based on data acquired with dedicated experimental measurements on a real machining centre, and a comparison with the most common practices in manufacturing is also reported. [ABSTRACT FROM PUBLISHER]

Automated manipulation of nanowires and nanotubes would enable the scalable manufacturing of nanodevices for a variety of applications, including nanoelectronics and biological applications. In this paper, we present an electric-field-based method for motion control, planning, and manipulation of nanowires in liquid suspension with a simple, generic set of electrodes. We first present a dynamic model and a vision-based motion control of the nanowire motion in dilute suspension with a set of N\times N controllable electrodes. Since the motion planning of a nanowire from one position to the target location is NP-hard, two heuristic algorithms are presented to generate near-optimal motion trajectories. We compare the heuristic motion planning algorithms with other existing algorithms such as the rapidly exploring random tree (RRT) and A^\ast algorithms. The comparisons show that the proposed heuristic algorithms obtain near-optimal minimum time trajectories. Finally, we demonstrate a single, integrated process to position, orient, and deposit multiple nanowires onto the substrate. Extensive experimental and numerical results are presented to confirm the motion control and planning algorithms. [ABSTRACT FROM PUBLISHER]

This paper proposes age and periodic replacement last models with continuous, and discrete policies. That is, an operating unit is replaced preventively at time T of operation as a strategic policy, or at a number N of working cycles to satisfy successive job completion, whichever occurs last. Such policies are named as replacement last, and their expected cost rates and optimal policies are obtained. However, the focus of this paper is to compare replacement last with replacement first policies, which are formulated under the classical assumption of whichever occurs first. From the points of cost and performability, different comparative methods for continuous and discrete optimizations are demonstrated to determine in what cases we should adopt replacement last rather than replacement first. All theoretical discussions in this paper are made analytically, and are computed numerically. [ABSTRACT FROM AUTHOR]