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Highly reliable and flexible control is required for distributed generation (DG) to efficiently connect to the grid. Smart inverters play a key role in the control and integration of DG into the power grid and provide advanced functionalities. In this paper, an energy-based single-phase voltage-source smart inverter (SPV-SSI) of 5 kVA is designed and analyzed in detail. SPV-SSI is capable of supplying the power to local load and the utility load up to the rated capacity of the inverter, injecting the power into the grid, storing the energy in lead-acid battery bank, controlling the voltage at the point of common coupling (PCC) during voltage sags or faults, and making decisions on real-time pricing information obtained from the utility grid through advanced metering. The complete design of smart inverter in dq frame, bi-directional DC-DC buck-boost converter, IEEE standard 1547 based islanding and recloser, and static synchronous compensator (STATCOM) functionalities is presented in this paper. Moreover, adaptive controllers, i.e., fuzzy proportional-integral (F-PI) controller and fuzzy-sliding mode controller (F-SMC) are designed. The performances of F-PI controller and F-SMC are superior, stable, and robust compared with those of conventionally tuned PI controllers for voltage control loop (islanded mode) and current control loop (grid-con-nected mode).

The paper is focused on AC railway traction system 25kV / 50Hz (respectively 60Hz). Currents progress at fields of power electronic allows to use semiconductors converter as a part of traction substations. It brings more advantages for operation modes of TSS (symmetrization, compensation, filtration, TSS cooperation, recuperation, etc.). The most promising topologies are described in the second half of the paper. The main benefit of the paper is comparison of TSS selected topologies.

Many thriving applications where isolation is required, such as traction and EV fast charging, implement solid-state transformers (SST). Half-cycle discontinuous-conduction-mode series resonant converters (HC-DCM-SRC) are suitable for these applications. The focus of this paper is to perform a comprehensive approach to HC-DCM-SRC and provide straight-forward requirements in order to ensure zero-loss switching (ZLS) of semiconductors. In addition, these requirements can be expressed as design boundaries for the transformer. Finally, the paper shows that, due to ZLS, silicon devices may have larger power capability than silicon-carbide switches. Therefore, IGBTs can be used instead of SiC MOSFETs, resulting in a significant cost reduction of the converter. This work was supported by the Spanish State Research Agency (AEI) under grant PID2019-110956RB-I00 and by the Public University of Navarre (UPNA) under a PhD scholarship

The paper is focused on topologies of traction substations for AC railway traction system especially for 25kV, 50Hz (respectively 60Hz). The current progress of power electronic field of study allows to use semiconductor converters as a part of distribution power grid (i.e. for HVDC), for traction issue but also for traction substations. This expansion is related to topologies of TSS, where power electronics are used for symmetrization, compensation, filtration of harmonics of higher order, TSS cooperation, recuperation back to distribution power grid if it is allowed, etc. Conventional transformer topologies used to this day for electrical railway supplies are described in the beginning. The state of the art of TSS, using a power electronic component and the most promising topologies at the same time, is described in the second half of the paper. The main benefit of the paper is comparison of the TSS selected topologies and evaluation of the properties.

International audience; Many works are dedicated to power electronic transformers in order to replace line frequency transformers. These new converters offer many degrees of freedom to the designer (switching frequency, magnetic material, rated voltage for switches…). This paper presents a methodology to optimize the sizing of such power converters in order to compare different topologies for a given application. The proposed procedure maximises the efficiency of the converter under a limited volume. In this paper, the methodology is applied to compare different topologies of power electronic traction transformers (PETT) for railway applications. The considered case is a 2 MW converter supplied by a 25 kV-50 Hz catenary. The procedure is illustrated in simulation on a converter with 3.3 kV SiC switches. The best obtained efficiency is 98.9% with 23 medium frequency transformers (MFT) of 28.6 L each.

This paper provides the performance data of Atlas plastic capacitors as supplied by Maxwell Technologies and Aerovox Corporation. The fiberglass cases are 13" high by 29" wide and 28" in depth with a 2" by 18" bushing on each end. Two styles of the 33.5 uF capacitors have been evaluated for Atlas use, a conventional paper-foil and a self-healing metalized-paper and plastic dielectric design. A test program to capacitor failure, is being used to evaluate capacitor lifetime at full voltage (60 kV) and a nominal 15% reversal. With the Atlas parameters, peak currents of /spl sim/340 kA are realized. In anticipation of faults, capacitors are capable, specified, and tested for 700 kA performance. Accurate methods are also utilized to determine capacitor inductance, less than 20 nH. The results of the various capacitor testing programs are presented in addition to future directives for our R&D efforts.

The Atlas pulsed power driver has recently been commissioned at Los Alamos National Laboratory. This paper provides an overview of the ATLAS facility, its initial experimental program and plans for the future. The reader desiring more detailed information is referred to papers in this conference by Keinigs et al. on materials studies, Cochrane et al. on machine performance and Ballard et al. on fabrication and assembly. Atlas is a high current generator capable of driving 30 megamps through a low-inductance load. It has been designed to require minimal maintenance, provide excellent diagnostic access, and rapid turnaround. Its capacitor bank stores 23.5 megajoules in a four-stage Marx configuration which erects to 240 kV at maximum charge. It has a quarter-cycle time of 4.5 microseconds. It will typically drive cylindrical aluminum liners in a Z-pinch configuration to velocities up to 10 mm/usec while maintaining the inner surface in the solid state. Diagnostic access includes 360/spl deg/ of radial view as well as axial views from above and below. The photograph shows the circle of tanks containing capacitor banks, the diagnostic platform and load area. Atlas construction began in 1996 and high-current acceptance tests were completed in December of 2000. Initial shots include liner characterization shots using a target design similar to NTLX experiments (see several papers by Turchi et al., this meeting). These will be followed by experiments studying hydro features, useful for validating hydrodynamic algorithms used in weapons computer codes. DOE plans to relocate the Atlas generator to the Nevada Test Site as early as 2002, where it will continue its experimental program supporting the Stockpile Stewardship program and other users.

This paper investigates the impact of load rejection over-voltage (LRO) from commercially available grid-tied photovoltaic (PV) inverters. LRO can occur when a breaker opens and the power output from a distributed energy resource (DER) exceeds the load. Simplified models of current-controlled inverters can over-predict LRO magnitudes, thus it is useful to quantify the effect through laboratory testing. The load rejection event was replicated using a hardware testbed at the National Renewable Energy Laboratory (NREL), and a set of commercially available PV inverters was tested to quantify the impact of LRO for a range of generation-to-load ratios. The magnitude and duration of the over-voltage events are reported in this paper along with a discussion of characteristic inverter output behavior. The results for the inverters under test showed that maximum over-voltage magnitudes were less than 200% of nominal voltage, and much lower in many test cases. These research results are important because utilities that interconnect inverter-based DER need to understand their characteristics under abnormal grid conditions.

For Electric Vehicles (EV), the charger is one of the main technical and economical weaknesses. This paper focuses on an original electric drive [1]–[3] dedicated to the vehicle traction and configurable as a battery charger without need of additional components. This cheap solution can outfit either electric or plug-in hybrid automotive vehicles, without needing additional mass and volume dedicated to the charger. Moreover, it allows a high charging power, for short duration charge cycles. However, this solution needs specific cares concerning the electrical machine control. This paper deals with the control of this drive [1], focusing on traction mode. In introduction, a review is done about topologies of combined on-board chargers. Then, the studied topology is introduced; using a 3-phase brushless machine supplied with a 6-leg Voltage Source Inverter (VSI). A model for its control is defined in the generalized Concordia frame, considering the traction mode. Then, an analysis of this model is established using a multimachine theory and a graphical formalism (the Energetic Macroscopic Representation denoted EMR). Using EMR, a description of energy flows shows specific control constraints. Indeed, numerical simulations illustrate the perturbations on the currents and the torque when controlling the machine with standard control methodologies. An improved control, deduced from the previous analysis, shows good performances, strongly reducing currents and torque ripples.

This paper puts forward a new practical voltage source converter (VSC) based AC-DC converter model suitable for conducting power flow assessment of multi-terminal VSC-based high-voltage direct current (VSC-MTDC) systems. The model uses an advanced method to handle the operational limits and control modes of VSCs into the power flow formulation. The new model is incorporated into a unified framework encompassing AC and DC power grids and is solved by using the Newton-Raphson method to enable quadratically convergent iterative solutions. The use of complementarity constraints, together with the Fischer-Burmeister function, is proposed to enable the seamless incorporation of operational control modes of VSC and automatic enforcement of any converter's operational limits that become violated during the iterative solution process. Thus, a dedicated process for checking limits is no longer required. Furthermore, all existing relationships between the VSC control laws and their operational limitsare considered directly during the solution of the power flow problem. The applicability of the new model is demonstrated with numerical examples using various multi-terminal AC-DC transmission networks, one of which is a utility-sized power system. publishedVersion

In a companion paper (Part I) the bar breakages for a 1.13 MW induction motor used in high speed railway traction drives were studied, by simulating the whole system (converter + motor) and by analyzing frequencies and amplitudes of current sidebands, for various loads (both active and inertial) and with increasing fault severity. It was recognized that faults can be characterized by (1-2s)f sideband, but results vary with load torque and drive inertia. Other sidebands appear less dependent from these disturbs, like (5+2s)f. Unfortunately, no works presented simple and general formulas about sidebands. In this paper, theoretical formulations for computation and prediction of rotor fault-related sideband frequencies and amplitudes are given, aiming to obtain relations useful for diagnostic purposes (fault severity assessment by MCSA), and by using Part I as a case-study. A decomposition by multiphase symmetrical components is performed, taking in account space harmonics. Formulas for (1-2s)f sideband amplitude are carried out, extendable to many other sidebands.

The HVDC superconducting cable, under development at the Los Alamos Scientific Laboratory will operate at a temperature of 12 R and a helium pressure of 1.38 MPa. Because dc breakdown data of dielectric materials at these operating conditions were not previously available, extensive tests were performed on 11 dielectric materials in sheet form. Three of these materials were impregnated with mineral oil, which increased their dc withstand strength significantly. Four of these 11 materials were selected for further tests at varying temperatures and pressures. The dc-breakdown field of cellulose paper (with and without oil impregnation) and PP/C (cellulose paper/polypropylene-celulose paper) varied as the exponential of the inverse of temperature. For the two polyethylene materials tested, the dc-breakdown strength showed a peak between 12 nd 298 K. Higher pressure increased the breakdown strength of the materials. Higher pressure or lower temperature also decreased the probability of surface flashover.

The paper deals with very long EHV cables (say, over 30 km) and their application in EHV mixed lines, i.e. those formed by a cable line between two sections of overhead lines. Such very special lines could be built for instance at the northern borders of Italy, laying the cable in the service gallery of the extra-long high-speed railway tunnels planned for construction under the Alps. EHV cable lines over 25-30 km long require the compensation of the reactive power generated by the cable, by means of fixed or variable shunt devices. After presenting expressions for the calculation of the maximum permissible length of EHV cable lines, the paper shows that 420 kV-50 Hz cable lines long up to 90-100 km, transmitting an active power up to 90% of the cable thermal limit, could be operated by using only two shunt reactors at the cable terminals. Fixed shunt reactors are adequate if the mixed line is practically symmetrical, i.e. the two stretches of the overhead line are of same length. On the other hand, if one of the overhead line sections is much longer than the other, or the terminal voltages of the mixed line are rather different, variable compensation allows to fully exploit the carrying capacity of the cable. The paper presents an algorithm to find the optimal taps of the variable shunt reactor. Results of the steady-state simulation of two hypothetical 420 kV-50 Hz mixed lines are finally reported, also showing that shunt reactors contain efficiently temporary overvoltages due to load rejection and no load energization.

The Italian blackout occurred on September 28th, 2003 started a deep critical revision of defence and restoration plans developed for the Italian national grid, and originated several tasks with the aim to improve the effectiveness of these plans. This paper deals with system restoration, and discusses some of the aspects concerning improvements of the Italian restoration plan. Touches of the topics in this paper are based on at development of innovative restoration paths, loaded through pumping storage plants instead of the usual distribution system loads. Details on the field test of the first new path are also reported.

Atlas will be a high-energy (36 MJ stored), high-power (/spl sim/10 TW) pulsed power driver for high energy-density experiments, with an emphasis on hydrodynamics. Scheduled for completion in late 1999, Atlas is designed to produce currents in the 40-50 MA range with a quarter-cycle time of 4-5 /spl mu/s. It will drive implosions of heavy liners (typically 50 g) with implosion velocities exceeding 20 mm//spl mu/s. Under these conditions, very high pressures and magnetic fields are produced. Shock pressures in the 50 Mbar range and pressures exceeding 10 Mbar in an adiabatic compression will be possible. By performing flux compression of a seed field, axial magnetic fields in the 2000 T range may be achieved. A variety of concepts have been identified for the first experimental campaigns on Atlas. Experimental configurations, associated physics issues, and diagnostic strategies are all under investigation as the design of the Atlas facility proceeds. Near-term proof-of-principle experiments employing the smaller Pegasus II capacitor bank have been identified, and several of these experiments have now been performed. This paper discusses a number of recent Pegasus II experiments and identifies several areas of research presently planned on Atlas.

OP VVV Electrical Engineering Technologies with High-Level of Embedded Intelligence CZ.02.1.01/0.0/0.0/18_069/0009855, project SGS 2021-021 This paper describes results of the harmonic analysis of currents harmonic analysis performed for an advanced AC traction Substation. AC traction substation feeding 25 kV / 50 Hz traction catenary and provide power symmetrization by semiconductor device called electronic balancer. The analysis is concern to currents of electronic balancer part of substation and the grid currents corresponding with quality of taken energy. The harmonic currents components are evaluate with the respect to the switching frequency of IGBTs (250 Hz), modulation technique (PS-PWM) and dead time duration (10 µs). The results are evaluated on the created model of the AC traction substation with multilevel converter topology, having the nominal power of 12.5 MVA.

This paper considers the design of a fiber-optic voltage sensor for applications in the field of wide area monitoring, protection and control of high voltage power networks. The proposed 132-kV sensor, combining a capacitive voltage divider (CVD) and an optical medium voltage transducer (MVT), was theoretically evaluated through software simulations and its expected performance was assessed based on the operational requirements specified by the IEC standards for electronic voltage transformers. The simulation results suggest that the sensor, when fabricated, should be capable of meeting the requirements for metering and protection classes specified by the IEC 60044–7 standard.

This paper presents a stimulator for a cardiac neuroprosthesis aiming to restore the parasympathetic control after heart transplantation. The stimulator is based on time-to- current conversion, instead of the conventional current mode digital-to-analog converter (DAC) that drives the output current mirrors. It uses a DAC based on capacitor charging to drive a power efficient voltage-to-current converter for output. The stimulator uses 1.8 V for system operation and 10 V for stimulation. The total power consumption is I stlm x 10 V + 18.4 μW during the biphasic current output, with a maximum I stim of 512 μΑ The stimulator was designed in CMOS 0.18 μm technology and post-layout simulations are presented.

The parallel connection of a Silicon (Si)-based IGBT and a Silicon Carbide (SiC)-based MOSFET forming a so called hybrid switch (HyS) can be used to exploit the advantageous features of both semiconductor and materials technologies. In this paper, a HyS-based inverter designed for the application of Electric Vehicle (EV) traction is compared to the conventional inverter assembled with Si-based IGBTs and SiC-based MOS-FETs. According to different standardized driving cycles, EVs operate in low partial load for a considerable amount of the time. Therefore, in this application, semiconductor conduction losses can be considerably reduced when unipolar switches such as MOSFETs are used. All in all, this work shows that the HyS configuration constitutes a good compromise between efficiency and cost when compared to the solution implementing only Si-based IGBT or solely SiC-based MOSFETs.

Compared to traditional unidirectional substations, a reversible substation (RSS) permitting bidirectional power flows is an efficient approach to recovering the braking energy of trains and increasing the energy efficiency of DC traction power supply systems (TPSS). This paper develops two models to reflect the role of an RSS under high and low fidelities, focusing on the converter- and TPSS-level simulation respectively. A particular RSS topology consisting of a 12-pulse diode rectifier and an antiparallel active neutral point clamped voltage source inverter (VSI) is replicated in a high-fidelity model where the VSI is controlled to maintain a constant DC voltage in the braking mode. To reduce computation burden, a low-fidelity model simplifies the rectifier into a diode in series with a controlled voltage source (CVS) that reflects its nonlinear output characteristics, and connects a DC voltage source in parallel with the CVS branch, permitting the delivery of braking power to the RSS under the constant DC voltage control. The two models are tested based on a simplified 1.5 kV TPSS and discussed alongside the consistency in the simulation of the power exchange and voltage transients at the RSS in traction and braking modes.

Dual active bridge (DAB) dc-dc converters have several attractive features including auto-adjust bidirectional power flow, wide voltage gain range, and zero voltage switching (ZVS)-on capability. Various applications based on DAB including solid-state transformer in power grids and traction, energy storage system, and electric vehicle on-board chargers have been proposed by academics. Nevertheless, industrial applications based on DABs are still seldom mainly due to the circulating current and loss of ZVS problems under certain load and voltage gain conditions. There is an intensive research effort underway to solve these problems recently. This paper presents the state-of-the-art view in the cause of circulating current and loss of ZVS and surveys the solutions to these problems.

This paper reports on the design, construction and initial testing of a fiber-optic voltage sensor for applications in the field of wide area monitoring, protection and control of high voltage power networks. The 132-kV sensor prototype, combining a capacitive voltage divider (CVD) and an optical low voltage transducer (LVT), was evaluated through laboratory testing and its performance was assessed based on the accuracy requirements specified by the IEC standards for low-power passive voltage transformers. The preliminary results show that the device has the potential to comply with the requirements of the 0,2 class for metering devices, and the 3P and 0,5P classes for protective and multipurpose devices, respectively, as specified by IEC 61869-11. As the device is based on a fiber Bragg grating written in a standard, low-loss, single-mode telecommunication fiber, it has the potential to be deployed as part of a distributed network of sensors along the power network over a wide geographical area, enabling novel power system protection and control strategies.

To establish a single European railway area, the European Commission requires, by 2019, that energy billings shall be computed on the actual energy consumed. So, in the near future, as required by EN 50463-2, all the trains shall be equipped with an Energy Measurement Function (EMF), whose measurement accuracy should be assessed and periodically re-verified. To answer to this emerging need, this paper presents a calibration system allowing the accurate testing of EMFs in DC conditions, up to 10 kV and 300 A, with arbitrary superimposed spectral component up to 10 kHz. It is able to reproduce all the tests prescribed by EN 504632, but, in order to characterize the EMF in actual operating conditions, also a number of possible synthetic complex waveforms and test signals acquired on board trains can be reproduced. Some testing results of an EMF, which uses voltage and current transducers typically installed in Italian electro-trains, are presented.

Noise in work places is a critical problem and inter-national regulations are becoming more restrictive on this aspect. The normal a-priori’ way of stating the workers’ exposure to the noise is becoming not enough to warrant that the worker is not exposed to a too high noise thus personal measuring systems are often required. In this paper one of these systems is described that is, not only capable of logging the noise the worker is subjected to, but also to raise an alarm if the noise seems to exceed the maximum allowed level. The system employs a 1$ microphone and off-the-shelf components and has a cost lower than 100$ so that any worker can be provided with a measuring system. The described solution connects to a central system via LoRa protocol without the necessity for the measuring system to be connected to the receiver or to be put close to it.

The low output voltage of energy harvester from ambient sources, such electrodynamic converters, makes the storage and use of energy in wireless sensors challenging. In this paper we propose an electromagnetic energy converter together with a novel energy management concept based on a nonlinear (Bistable) Random Mechanical Switching Harvesting on Inductor (RMSHI). The electromagnetic converter consists of a moving coil attached to a mechanical spring. It is able to harvest energy even from very weak vibrations close to 9 m/s2 of applied acceleration. In particular the conceived structure works also in presence of random and voltage amplitude generated from the electromagnetic harvester less than bridge rectifier threshold (∼1.4 V). We have already demonstrated the capability of the RMSHI in order to work as “unsynchronized” approach able to collect energy by using linear transducers (i.e. PZT oscillators, AlN Bridges, etc.). Here we propose a bistable-RMSHI with an electromagnetic harvester to improve its performance in presence of random kinetic sources. The system has been studied, realized and characterized, demonstrating the validity of our approach.

This paper introduces a technique for the supervised segmentation of Air-Tissue Boundaries (ATBs) in the upper airway of the vocal tract in the real time magnetic resonance imaging (rtMRI) videos. The proposed technique uses a novel measure of contrast across a boundary using Fisher discriminant function. ATBs in all frames of an rtMRI video are jointly estimated by maximizing the proposed measure of contrast around the predicted ATBs and incorporating a smoothness constraint to ensure the ATBs in consecutive frames do not change drastically. Dynamic programming is used for this purpose. The accuracy of the proposed technique is evaluated separately for the upper and lower ATBs using the Dynamic Time Warping distance between the predicted and the ground truth contours. Experiments with rtMRI videos from four subjects show that the error in ATB prediction using the proposed technique is 8.99% less than that using a semi-supervised grid based segmentation approach. A key feature of the proposed approach is that it can reliably predict the ATB outside the vocal tract unlike those with the existing methods.

There is a growing need for plenarily automated algorithms that expeditiously localize the optic disc region in retinal fundus images for the analysis of retinal pathologies such as glaucoma. In this paper, we propose a methodology based on particle swarm optimization for automatic localization of optic disc region from retinal fundus images, where minimization of the fitness function is utilized to resolve optimization quandaries. Here, kernels are modeled as particles and they test the region-of-interest based on the fitness function, in the respective databases, where it is likely that the optic disc exists. The proposed method is validated on a total of 1670 fundus images obtained from various publicly available fundus image datasets. The optic disc localization accuracy obtained by the proposed method are 100%, 98.01%, 96.15%, 98.87%, 100%, and 100% on DRIVE, DRISHTI-GS, DIARETDB0, DIARETDB1, DRIONS-DB, and MESSIDOR fundus image databases, respectively. The precision of localization was improved with initialization of kernel particles within bright region-of-interest in fundus images.

This paper presents the development of a DC-DC buck converter based static excitation system for a micro-alternator. The IGBT based AC to DC converter is used as Front End Converter (FEC) followed by a buck converter to control the field voltage of micro-alternator. TMS320F28377S microcontroller is used for digital implementation of the Automatic Voltage Regulator (AVR). A proportional integral(PI) controller is used in the AVR. The proposed system is tested under various small and large disturbances like change in the reference voltage, 3-phase fault at generator terminal, and sudden load rejection to study the performance of the proposed excitation system.

Automatic detection of optic disc and fovea is a precursor to the computer-aided analysis of retinal pathologies. In this paper, we present a unified approach for optic disc and fovea detection based on normalized cross-correlation technique. The algorithm performance is optimized by introducing vector inner products and norms instead of conventional mean and variance computations. We report optic disc detection results on four publicly available fundus image databases amounting to a total of 1451 fundus images and fovea detection results on another four publicly available fundus image databases amounting to a total of 1454 fundus images. The proposed method results in an optic disc detection accuracy of 99.01%, 95.67%, 99.09%, and 100% on DRISHTI-GS, MESSIDOR, DRIONS-DB, and DRIVE fundus image databases, respectively, and fovea detection accuracy of 94.83%, 84.62%, 95.51%, and 97.14% on MESSIDOR, DIARETDB0, DIARETDB1, and DRIVE fundus image databases, respectively. The speed of optic disc and fovea detection has been improved considerably by downsampling technique. In addition, we report the effect of downsampling on the detection accuracy.

In this paper, a 2-D vector flow imaging (VFI) method developed by combining synthetic aperture sequential beamforming and directional transverse oscillation is used toimage a carotid bifurcation. Ninety-six beamformed lines are sent from the probe to the host system for each VFI frame, enabling the possibility of wireless transmission. The velocity is estimated using a relatively inexpensive 2-D phase-shift approach, and real-time performance can be achieved in mobile devices. However, high-frame-rate velocities can be obtained by sending the data to a cluster of computers. The objective of this study is to demonstrate the scalability of the method’s performance according to the needs of the user and the processing capabilities of the host system. In vivo measurements of a carotid bifurcation of a 54-year-old volunteer were conducted using a linear arraytransducer connected to the SARUS scanner. The velocities were estimated at a rate of 134 independent frames per second (FPS) to reveal complex flow patterns. A peak frame rate of 2140 FPS can be obtained by generating the images recursively. VFI images are shown during the systolic phase revealing the formation of a vortex in the internal carotid artery. The peak systolic velocity from a range gate in the common tract was 0.76 m s−1 with a standard deviation (SD) of 6.1%. The mean velocity profile was calculated from the same range gate with an average SD of 7.86%.

Date of Conference: 15-18 May 2017 Conference Name: IEEE 25th Signal Processing and Communications Applications Conference, SIU 2017 Quantifying the effects of blood pressure (BP) changes on the ballistocardiogram (BCG) signal shape and features can potentially improve the understanding of this mechanical modality of cardiovascular sensing. BCG, a measure of body movements caused by ejection of blood into the vasculature, has recently re-emerged as a promising method for trending cardiac output and myocardial contractility. Although recent research has shown that the BCG waveform has the potential to be used as a viable proximal timing reference for measuring pulse transit time (PTT) and indirectly BP, it has not been deeply explored for direct estimation of BP. In this paper, we posit that the BCG signal contains features corresponding to changes in BP. To further investigate this hypothesis, BCG waveforms were measured using a modified-weighing scale from 14 subjects performing an isometric handgrip challenge in a seated position. The energy in the latter half of the BCG heartbeat was estimated using polynomial fitting and interpolation methods. The results indicate that an increase in mean arterial pressure (MAP) or a decrease in PTT manifests itself in the form of high amplitude oscillations following the main peak (J-peak) in a BCG heartbeat, thus elucidating the mechanisms behind these oscillations and also potentially improving the breadth of data that can be sensed using BCG signals.

This paper relates to a genuine wrist pulse oximeter, which is a noninvasive medical device that can measure the pulse rate and oxygen saturation level in a person's blood. The device is novel due to its innovative design. It is a new type of reflective oximeter, which has a concave structure for housing the optical source and sensor. The neo-reflective sensor module of the device is designed to send the sensor data to a nearby intelligent mobile phone using wireless data transmission. The pulse oximeter has been developed and calibrated, and the calibration curve was analyzed. The innovative design of this pulse oximeter would enable the user to wear the low-cost device on one wrist continuously throughout the day, without the inconvenience of a conventional finger pulse oximeter.

Fluid accumulation inside the lungs, known as cardiac pulmonary edema, is one of the main early symptoms of congestive heart failure (CHF). That accumulation causes significant changes in the electrical properties of the lung tissues, which in turn can be detected using microwave techniques. To that end, the design and implementation of an automated ultrahigh-frequency microwave-based system for CHF detection and monitoring is presented. The hardware of the system consists of a wideband folded antenna attached to a fully automated vertical scanning platform, compact microwave transceiver, and laptop. The system includes software in the form of operational control, signal processing, and visualizing algorithms. To detect CHF, the system is designed to vertically scan the rear side of the human torso in a monostatic radar approach. The collected data from the scanning is then visualized in the time domain using the inverse Fourier transform. These images show the intensity of the reflected signals from different parts of the torso. Using a differential based detection technique, a threshold is defined to differentiate between healthy and unhealthy cases. This paper includes details of developing the automated platform, designing the antenna with the required properties imposed by the system, developing a signal processing algorithm, and introducing differential detection technique besides investigating miscellaneous probable CHF cases.

Insulating oils are widely used in power transformers. The oil insulation degrades under multiple stresses during the transformer operation, which affects the insulation integrity and consequently could cause transformer failures. DC resistivity is one of the dielectric parameters of insulating oil for assessing transformer insulation conditions. This paper presents results of DC resistivity measurements of oil samples including a mineral oil and a synthetic ester in fresh and thermally-aged conditions as well as two in-service aged oil samples in a cylindrical test cell under temperature range of 20oC to 100oC.Two standards of DC resistivity measurement namely IEC 60247 and ASTM D 1169 were applied. For mineral oil, the results of ASTM D 1169 are higher than those of IEC 60247 which is caused by polarity dependence of DC resistivity. For the other samples, the results are the same for both standards. Further investigation on polarity dependence shows that it might be caused by different ion injection strength of the inner and outer electrodes.

This paper presents an integrated MRI-compatible full-bridge Class-DE ultrasound transducer driver design for HIFU applications. This design includes a digital logic unit to individually control the phase and duty ratio of each transducer when the driver is used in an array configuration. This work also shows the performance of the proposed driver with three different ultrasonic transducers. Simulation results predict at least 89% efficiency for the two transducers that support ideal Class-DE operation without matching networks. The proposed driver has been implemented by using AMS AG H35 CMOS process. The total die area of the driver is 3 mm2.

This paper presents a system on chip for a fully implantable cochlear implant. It includes acoustic sensor front-end, 4-channel digital sound processing and auditory nerve stimulation circuitry. It also features a digital, switched mode, single inductor dual output power supply that generates two regulated voltages; 0.4 V used to supply on-chip digital blocks and 0.9 V to supply analog blocks and charge the battery when an external RF source is detected. All passives are integrated on-chip including the inductor. The system was implemented in 14nm CMOS and validated with post layout simulations.

Streaming electrification has been identified as one of the main failure reasons for large power transformers. Different measurement methods including pipe flow method, rotating disk method and mini-static tester have been proposed to investigate this phenomenon. In this paper, a small scale laboratory based pipe flow model is established. The streaming electrification characteristics of a conventional mineral oil and a synthetic ester liquid were compared. Parameters including flow velocity, pressboard condition and oil aging were studied. The results indicate that the ester liquid exhibits a much higher streaming current than the mineral oil at the investigated flow velocities. Aging of the oil facilitates the charging process in the mineral oil but decreases the streaming current in the ester liquid.

When a single line to ground fault happens on the MV side of a HV/MV system, only a small portion of the fault current is injected into the ground by the ground-grid of the faulty substation. In fact the fault current is distributed between grounding electrodes and MV cables sheaths. In systems with isolated neutral or with resonant earthing this may be sufficient to provide safety from electric shock. Experimental measurements were performed on a real MV distribution network: a real single line to ground fault was made and fault currents were measured in the faulty substation and in four neighboring substations. In this paper the problem of fault current distribution is introduced, the test system is described and the measurements results are presented.

Glaucoma is currently one of the major causes of vision loss worldwide. Though the lost vision capability cannot be recovered, preventive steps such as clinical diagnosis and necessary treatment can be taken in order to minimize visual impairment due to glaucoma. The process of clinical diagnosis needs manual examination and outlining of the optic disc and cup, which is subjective and time consuming. In this paper, we propose a methodology for automatic segmentation and outlining of the optic disc using an active disc formulation. The method uses a disc template as a prototype. The initialization is automated using a matched filtering technique. We choose the disc to be isotropic, and allow for translation, isotropic scaling, and optimization of the corresponding parameters. The active disc is evolved towards the boundary of the optic disc by minimizing a local energy function. We report validations on three publicly available databases MES-SIDOR, DRIONS-DB, and Drishti-GS containing 1200, 110, and 101 retinal fundus images, respectively. The corresponding F-scores 0.8456, 0.8380, and 0.9077, respectively, for the databases show robustness, and high correlation of the proposed algorithm with the expert segmentation.

The paper shows the methods of spectral analysis of stochastic traction voltages and currents. The results of analysis are shown for the voltage, which has been recorded in the process of real operation of EPL2T electric multiple-unit train.

From viewpoints of low environment impact, Palm Fatty Acid Ester oil (PFAE) is potent insulating liquid for power transformers because of its high biodegradation performance. Moreover, PFAE has high permittivity, low viscosity, high thermal and chemical stability and high productivity. These characteristics well satisfy the requirement of electric insulation performance in power transformers. In this paper, electric field distribution in a PFAE / pressboard insulation system was measured with a Kerr electro-optic technique at various oil flow conditions under dc voltages and the charge behavior was investigated systematically. We discussed the difference of the flow electrification characteristics between PFAE and mineral oil, and its mechanism was discussed based on the charge behavior in oils.

In this paper authors present a method for optimal sizing of supercapacitor (SC) energy storage system (ESS) for braking energy recovery in tram network. The method is applicable for segmented tram networks with radial feeding topology and a stationary storage system installed in traction substation. The method is demonstrated for one traction substation of Riga public transport network.

ALFA (Absolute Luminosity For ATLAS) is one of the sub-detectors of ATLAS (A Toroidal LHC Apparatus). The ALFA system is composed by four stations installed in the LHC tunnel 240 m away from the ATLAS interaction point. Each station has a vacuum and ventilation system, movement control and all the required electronics for signal processing. The Detector Control System (DCS) provides control and monitoring of several components and ensures the safe operation of the detector contributing to good Data Quality. This paper describes the ALFA DCS system including a detector overview, operation aspects and hardware control through a SCADA system, WinCC OA.

This paper presents a wireless energy link for rechargeable implantable pulse generators for deep brain stimulation. The proposed link exploits a magnetic coupling between two compact planar resonators. From experimental results referring to a prototype working in the MedRadio band a transfer efficiency of about 10.62% is demonstrated.

This paper shows an effective implementation of the fast charging concept in the electric local public transport context. An electric minibus powered with a lead-acid battery is considered as a case-study. Its traction battery is redesigned using 12 V standard lithium-iron-phosphate modules to benefit from the higher performance of the lithium battery technology compared to the lead-acid one. The minibus can achieve a continuous operation characterised by 20 min of traveling alternated with 10 min of standstill for fast recharging of the battery. Experiments performed on a single module of the battery show that the load profile is sustained without appreciable issues both in temperature and life degradation of the lithium cells. © 2015 IEEE.

Global earthing systems (GESs), created by the interconnection of local earthing systems, should guarantee the absence of dangerous touch voltages. One of the reasons for this safety characteristic of GESs is the fault current distribution between grounding electrodes and medium-voltage (MV) cable sheaths: Only a small portion of the fault current is injected into the ground by the ground grid of the faulty substation. In systems with isolated neutral or with resonant earthing, this effect may be sufficient to provide safety from electric shock. In this paper, a model describing the behavior of the MV distribution system with interconnected grounding electrodes during a ground fault is built. It is then used to analyze the impact of different factors on the fault current distribution. A sensitivity analysis is performed, varying the main parameters, and the results are used to draw some conclusions on the current distribution influence on GESs.

When a single line to ground fault happens on the MV side of a HV/MV system, only a small portion of the fault current is injected into the ground by the ground-grid of the faulty substation. In fact the fault current is distributed between grounding electrodes and MV cables sheaths. In systems with isolated neutral or with resonant earthing this may be sufficient to provide safety from electric shock. Experimental measurements were performed on a real MV distribution network: a real single line to ground fault was made and fault currents were measured in the faulty substation and in four neighbouring substations. In this paper the problem of fault current distribution is introduced, the test system is described and the measurements results are presented.

In the future, environmentally friendly insulating oil such as rapeseed ester oil is expected to be utilized as a substitute for mineral oil for power transformers. In addition, electrical insulation design for transformers becomes more important regarding size reduction and enhancement of electric field stress. The fundamental property of the electric field distribution in the rapeseed ester oil and in the oil / solid dielectrics composite insulation system should be clarified. In this paper, we have directly measured the electric field in the rapeseed ester oil with parallel-plane electrode and the rapeseed ester oil / pressboard (PB) composite insulation systems under dc voltage application using the Kerr electro-optic technique. From the results, we compared measurements of electric field and charge behavior for the rapeseed ester oil and the mineral oil and confirmed the applicability of the rapeseed ester oil for use in transformers.

In this paper, a design of truly non-invasive continuous blood glucose monitoring sensor which uses a pair of microwave split ring resonators is presented, operating around 1.4 GHz. The rings are made from silver coated copper wire. In addition to the sensing ring, a reference ring is added which operates at a higher frequency. This is used to take into account the temperature dependent expansion of the ring and to calibrate out any effects due to changes in temperature. The proposed sensor made up of the pair of rings is directly attached onto the skin in the abdominal area by using an adhesive patch. For validation, we have tested the proposed sensor simultaneously with two commercially available sensors (blood strip and continuous glucose monitor) over 12 hour periods with 3 food events, with encouraging correlation of our blood glucose results with those of the commercial sensors.