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This paper proposes a decentralized control based on static var compensator (SVC) devices to improve the frequency control of high voltage transmission systems. For a realistic structure preserving power system with voltage dependent loads, we propose a sufficient condition based on a strict Lyapunov energy function, which is utilized to design a nonlinear adaptive SVC controller. This controller only requires local bus measures and parameters. Furthermore, we also present an SVC with a conventional frequency droop controller. The performance of the two considered SVC control systems are evaluated on the well known IEEE New England 39-bus 10-machine power system and compared with conventional SVC controllers. [ABSTRACT FROM AUTHOR]

The objective of this study is to identify and eliminate unnecessary iteration loops in the load flow analysis of an active distribution network so as to improve its overall computational efficiency. The number of iteration loops is minimised through the integrated modelling of a distributed generator (DG) and the associated coupling transformer. The DG bus is not preserved in the load flow calculation and the aforementioned DG-transformer assembly is represented in the form of a voltagedependent negative load at the point of connection to the main distribution network. Thus, the iteration stage that is involved in indirectly preserving the DG in the form of a voltage source or negative constant power load can be eliminated. This, in turn, eliminates the need for multiple rounds of forward-backward sweeps (FBS) iterations to determine the bus voltages. The power characteristics of the DG-transformer assembly are thoroughly investigated through a carefully performed case study so as to assess the general convergence performance of the proposed load flow algorithm. Furthermore, extensive comparative studies are carried out to verify the computational efficiency attained via the proposed DG modelling in the load flow analysis of an active distribution network. [ABSTRACT FROM AUTHOR]

Abstract The ability to detect and determine a typically weak internal photoemission (IPE) signal from a usually strong photoconductivity (PC) signal within a spectral response (SR) measurement can be helpful in studying the interface properties of metal-semiconductor junctions, which are often critical for proper design and analysis of semiconductor electronic devices including organic photovoltaic devices. In this report, we propose a method to discern the voltage dependent IPE component from PC content in a measured SR of organic devices. The method is based on the ratio of SR measured at different voltage bias conditions in metal-organic semiconductor-metal devices. The separated IPE component, hence, can be used to estimate the associated interface barrier(s). The differentiation between IPE and PC is probably caused due to the barrier changing at the metal and organic semiconductor interface on the application of bias which causes a modulation in IPE signal with the applied bias. In this work, a theoretical basis for the method of characterisation has been developed. Based on the analysis, as an example, the barriers between [6,6] phenyl C61 butyric acid methyl ester (PCBM) and electrodes indium tin oxide and aluminium for different bias voltages have been evaluated. This simple and elegant method of studying metal and organic semiconductor barrier, when applicable, can be helpful in device design and characterisation. Graphical abstract Image 1 Highlights • Technique that identifies internal photoemission signal within spectral response. • Deviation in spectral response signal ratio at different biases modelled. • Multi-bias spectral response ratios analysed to estimate charge carrier barriers. [ABSTRACT FROM AUTHOR]

Abstract The simulation of solar cell devices is important for the understanding of defect physics and loss mechanisms in real solar cells. On the other hand, voltage dependent admittance spectroscopy delivers essential information for establishing a baseline simulation model of Cu(In,Ga)Se 2 (CIGSe) solar cells. Here we give an explanation for the weak temperature dependence of the N1-signal, the latter being not compatible with a bulk defect or with a simple hole barrier at the Mo back contact. Furthermore, we find a E d,IF – E V ≈ 0.3 eV deep recombination-active acceptor state at the absorber/buffer interface made of air-light exposed CIGSe absorbers. This gives us the ability to explain the reduction of power conversion efficiency of solar cells made from air-light exposed absorbers. From the voltage dependent capacitance step of this interface defect we can deduce the formerly unknown position of the Fermi level at the hetero junction in equilibrium which is close to mid-gap. Simulation of dark J-V curves allows a refinement of the parameter of this absorber/buffer interface defect, resulting in a defect density of N d,IF ≈ 3.5·1011 cm−2 as well as capture cross sections of σ n ≈ 4·10−16 cm2 for electrons and σ p ≈ 3·10−11 cm2 for holes. Highlights • Defect spectroscopy of solar cells with air-light exposed Cu(In,Ga)Se 2 layers. • Recombination-active acceptor states at the absorber/buffer interface. • Signature analysis of voltage dependent admittance spectroscopy. • Interpretation of the N1 feature in admittance measurements. • Simulation model of Cu(In,Ga)Se 2 solar cells. [ABSTRACT FROM AUTHOR]

Copyright of Online Turkish Journal of Health Sciences (OTJHS) / Online Türk Sağlık Bilimleri Dergisi is the property of Oguz KARABAY and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Perylene-diimide (PDI) organic semiconductor was prepared on n-type Si wafer using spin coating method. The dielectric permittivity, conductivity and electric modulus properties of PDI structure were characterized by means of the capacitance-voltage and the conductance-voltage measurements at the voltage range from 0 V to 300 mV and the frequency range from 30 kHz to 1 MHz. It is observed that the dielectric dispersion is uniformly decreased with the frequency, and then approach nearly to a fixed value at higher frequencies. However, the imaginary (M″) part of electric modulus has a peak for all the applied voltage values and the peak shifts to the higher frequencies with decreasing voltage. The peak observed in the figure is attributed to the dielectric relaxation. Furthermore, it has been reported that the Cole-Cole curves has one relaxation. [ABSTRACT FROM AUTHOR]

This study was designed to unveil effects of 5-nm sized, polyvinylpyrrolidone-coated gold nanoparticles (AuNPs) on vascular Ca V 1.2 and Ca V 3.1 channels. Ba 2+ currents through both channels (I Ba1.2 and I Ba3.1 ) were recorded in single myocytes isolated from the rat tail main artery by means of the whole-cell patch-clamp method. AuNPs increased I Ba1.2 and I Ba3.1 amplitude in a concentration- and V h -dependent manner. Neither the voltage dependence of inactivation and activation curves nor inactivation and activation kinetics were affected by AuNPs. In conclusion, these findings warrant further investigation to clarify whether different types of NPs possess the same stimulatory activity and may represent a toxic hazard to humans. [ABSTRACT FROM AUTHOR]

A single-cell-gap transflective polymer-stabilised blue-phase liquid crystal display with opposite polar pixel electrodes on an etched substrate is proposed. In the proposed structure, the space between common electrodes is adopted as transmissive region, and the space above the common electrode is adopted as reflective region. By optimising the electrode parameters of the transmissive and reflective regions, well-matched voltage-dependent transmittance and reflectance curves can be obtained. In addition, the device has good performances of low operating voltage (~3.2 V), high optical efficiency and a wide viewing angle. [ABSTRACT FROM AUTHOR]

In this paper, bridge type fault current limiter (BFCL) is proposed as a potential solution to the fault problems of permanent magnet synchronous generator (PMSG) based large-scale wind energy system. As PMSG wind system is more vulnerable to disturbances, it is essential to guarantee the stability during severe disturbances by enhancing the fault ride through capability. BFCL controller has been designed to insert resistance and inductance during the inception of system disturbances in order to limit fault current. Constant capacitor voltage has been maintained by the grid voltage source converter (GVSC) controller while current extraction or injection has been achieved by machine VSC (MVSC) controller. Symmetrical and unsymmetrical faults have been applied in the system to show the effectiveness of the proposed BFCL solution. PMSG wind system, BFCL and their controllers have been implemented by real time hardware in loop (RTHIL) setup with real time digital simulator (RTDS) and dSPACE. Another significant feature of this work is that the performance of the proposed BFCL is compared with that of series dynamic braking resistor (SDBR). Comparative RTHIL implementation results show that the proposed BFCL is very efficient in improving system fault ride through capability by limiting the fault current and outperforms SDBR. [ABSTRACT FROM AUTHOR]

Fe doped Ni2Mn1.5In0.5, particularly, Ni2Mn1.4Fe0.1In0.5, despite having an incommensurate, modulated 7M martensitic structure at room temperature exhibits frequency dependent behavior of storage modulus and loss which obeys the Vogel-Fulcher law as well as shows ergodicity breaking between zero field cooled and field cooled strain measurements just above the transition temperature. Both frequency dependence and ergodicity breaking are characteristics of a strain glassy phase and occur due to the presence of strain domains which are large enough to present signatures of long range martensitic order in diffraction but are non-interacting with other strain domains due to the presence of Fe impurities. [ABSTRACT FROM AUTHOR]

Although single-crystalline spinel (MgAl2O4)-based magnetic tunnel junctions (MTJs) are known to show a good bias voltage dependence of a tunnel magnetoresistance (TMR) ratio over MgO-based MTJs, no polycrystalline MgAl2O4-based MTJs exhibiting large TMR ratios have been grown previously due to the lack of crystallinity of the MgAl2O4 barrier. In this work, we demonstrate the growth of polycrystalline-based MTJs with large TMR ratios exceeding 240% and an improved bias voltage dependence compared to that of MgO-based MTJs. An ultra-thin CoFe/MgO seed layer on the amorphous CoFeB layer induced the growth of a highly (001)-textured MgAl2O4 barrier, which worked as a template layer for the solid epitaxy of CoFe grains during the crystallization of the CoFeB layers. High resolution scanning transmission electron microscopy shows lattice-matched epitaxy between the (001)-textured MgAl2O4 barrier and CoFe grains. This study demonstrates the industrial viability of MgAl2O4-based polycrystalline MTJs with an improved bias voltage dependence. [ABSTRACT FROM AUTHOR]

Fe doped Ni2Mn1.5In0.5, particularly, Ni2Mn1.4Fe0.1In0.5, despite having an incommensurate, modulated 7M martensitic structure at room temperature exhibits frequency dependent behavior of storage modulus and loss which obeys the Vogel-Fulcher law as well as shows ergodicity breaking between zero field cooled and field cooled strain measurements just above the transition temperature. Both frequency dependence and ergodicity breaking are characteristics of a strain glassy phase and occur due to the presence of strain domains which are large enough to present signatures of long range martensitic order in diffraction but are non-interacting with other strain domains due to the presence of Fe impurities. [ABSTRACT FROM AUTHOR]

This paper focuses on a tuning-less model predictive control (MPC) strategy with unbalanced fault-ride-through capability for a three-phase modular multilevel converter (MMC). Three individual control stages are designed to cater for the multiple control objectives in MMC without the need for any weighting factor tuning. A conceptually simple power regulation approach which requires neither synchronous coordinate transformation nor grid-voltage phase angle detection is introduced into the proposed MPC. Meanwhile, two alternatives are proposed to the power regulation stage to adapt to the special needs under unbalanced grid fault. Neither of the alternatives involves any tuning work. In addition, a modified sorting algorithm is presented to resolve the problem of unnecessary switching transitions, which is inherent in conventional sorting algorithm. The proposed tuning-less MPC is capable of direct active and reactive power control, circulating current minimization, submodule capacitor voltage balancing, switching frequency reduction, and great resilience under balanced and unbalanced grid conditions. The presented simulation results confirm the effectiveness and feasibility of the proposed control method. [ABSTRACT FROM AUTHOR]

Understanding the dynamic processes of a real game system requires an appropriate dynamics model, and rigorously testing a dynamics model is nontrivial. In our methodological research, we develop an approach to testing the validity of game dynamics models that considers the dynamic patterns of angular momentum and speed as measurement variables. Using Rock–Paper–Scissors (RPS) games as an example, we illustrate the geometric patterns in the experiment data. We then derive the related theoretical patterns from a series of typical dynamics models. By testing the goodness-of-fit between the experimental and theoretical patterns, we show that the validity of these models can be evaluated quantitatively. Our approach establishes a link between dynamics models and experimental systems, which is, to the best of our knowledge, the most effective and rigorous strategy for ascertaining the testability of evolutionary game dynamics models. [ABSTRACT FROM AUTHOR]

To understand how single neurons process sensory information, it is necessary to develop suitable stochastic models to describe the response variability of the recorded spike trains. Spikes in a given neuron are produced by the synergistic action of sodium and potassium of the voltage-dependent channels that open or close the gates. Hodgkin and Huxley (HH) equations describe the ionic mechanisms underlying the initiation and propagation of action potentials, through a set of nonlinear ordinary differential equations that approximate the electrical characteristics of the excitable cell. Path integral provides an adequate approach to compute quantities such as transition probabilities, and any stochastic system can be expressed in terms of this methodology. We use the technique of path integrals to determine the analytical solution driven by a non-Gaussian colored noise when considering the HH equations as a stochastic system. The different neuronal dynamics are investigated by estimating the path integral solutions driven by a non-Gaussian colored noise q . More specifically we take into account the correlational structures of the complex neuronal signals not just by estimating the transition probability associated to the Gaussian approach of the stochastic HH equations, but instead considering much more subtle processes accounting for the non-Gaussian noise that could be induced by the surrounding neural network and by feedforward correlations. This allows us to investigate the underlying dynamics of the neural system when different scenarios of noise correlations are considered. [ABSTRACT FROM AUTHOR]

For maximum power point (MPP) application, the transient evolution of capacitor can be exploited to examine the power-voltage (P-V) characteristics of a photovoltaic (PV) array. This method is simple and inexpensive. In addition, it can be implemented on any array size whether un-shaded or partially shaded. This paper presents a new MPPT technique that scans the P-V curve of PV array with a series capacitor (C scan ) through a unique H-bridge architecture. The proposed technique employs a simple algorithm, which controls the H-bridge to scan the P-V curve in two sequences: (1) during charging of capacitor, and (2) during discharging of capacitor. The proposed MPPT neither requires the isolation of PV array from load nor executes power loss during checking of P-V curve. The effects of input capacitor (C in ) of converter during scanning of P-V curve are comprehensively discussed, and then the correct sizing of C scan according to array size is explained with a design example. A comparative analysis of different MPPTs in the context of tracking ability, dynamic, and steady state efficiencies is presented. This analysis highlights the advantage of proposed technique over other MPPTs. Finally, the fundamental operation of proposed MPPT is verified through experimental results. [ABSTRACT FROM AUTHOR]

The electrical and dielectric properties of TiN/Al 2 O 3 /p-Si MIS structure were studied in the temperature range of 380–450 K at 1 MHz. These properties were calculated from experimental C − V and G / ω − V measurements. Experimental results show that the forward bias C − V plots exhibit a distinct peak at high temperatures, this Kind of behavior is mostly attributed to the series resistance ( R s ) and interface states ( N s s ) between Al 2 O 3 /p-Si. The temperature and bias voltage dependence of dielectric constant ( ε ′ ) , dielectric loss ( ε ″ ) , dielectric loss tangent ( tan δ ) and the ac electrical conductivity ( σ a c ) are studied for TiN/Al 2 O 3 /p-Si MIS structure. Experimental results show that the values of ε ′ and ε ″ depend on the variation of both bias voltage and temperature. The C − V and G / ω − V characteristics prove that the R s and N s s of the diode are important parameters that strongly influence the electric parameters in MIS device. The density of N s s , depending on the temperature, was determined from the C − V and G / ω − V data using the Hill-Coleman Method. The Arrhenius plot of the ac conductivity at 1 MHz is illustrated and the activation energy is found to be E a = 0.012 e V . Moreover, the electric modulus formalisms were employed to understand the relaxation mechanism of the TiN/Al 2 O 3 /p-Si structure. [ABSTRACT FROM AUTHOR]

Capacitance boxes (CBs) are extensively used in electrical laboratories for calibration of capacitance measurement devices. In this paper, a new recently fabricated CB has been presented to be used for automatic calibrations through its 4096 output capacitance steps in the range from 100 nF to 150 mF. Full specifications and characterization of this new CB have been investigated in detail including its frequency and voltage dependences. The presented CB has relative accuracy in the range from ±5×10±5 to ±5×10-4, whereas the relative uncertainty due to the combination effect is less than 15 ppm. The described CB has been used to construct fully automated capacitance measurement system at the National Institute of Standards (NIS), Egypt, using Andeen-Hagerling 2700A, opt. E & opt. C, Ultra-precision Capacitance Bridge up to 1 mF. The second fully automated system for capacitance measurements is formed at NIS by An Agilent E4980A LCR meter, which is used to measure and characterize the higher capacitance values of the fabricated automated CB. Technical comparison between a previous CB and the new introduced one has been done to evaluate its performance. [ABSTRACT FROM AUTHOR]

This article investigates the effective liquid–gas surface tension changes of water and 5–90 nm gold nanofluids measured during electrowetting on dielectric experiments. The Young–Laplace equation for sessile droplets in air was solved to fit the experimental droplet shape and determine the effective liquid–gas surface tension at each applied voltage. A good agreement between experimental droplet shapes and the predictions was observed for all the liquids investigated in applied range of 0–30 V. The measured liquid–gas effective surface tensions of water and gold nanofluid decreased with voltage. At a given voltage, the effective liquid–gas surface tension of gold nanofluids initially decreased as the size of gold nanoparticles increased from 5 nm to 50 nm. Then, for 70 nm and 90 nm particle gold nanofluids, the effective liquid–gas surface tension started increasing too. The size of nanoparticles, and the applied voltage have a significant effect on variation of the effective liquid–gas surface tension with variations as much as 93% induced by voltage at a given particle size and 80% induced by particle size at a given voltage. [ABSTRACT FROM AUTHOR]

The chloride channel (CLC) family of proteins consists of channels and transporters that share similarities in architecture and play essential roles in physiological functions. Among the CLC family, CLC-1 channels have the representative homodimeric double-barreled structure carrying two gating processes. One is protopore gating that acts on each pore independently by glutamate residue (E). The other is common gating that closes both pores simultaneously in association with large conformational changes across each subunit. In skeletal muscle, CLC-1 is associated with maintaining normal sarcolemmal excitability, and a number of myotonic mutants were reported to modify the channel gating of CLC-1. In this study, we characterized highly conserved helix O as a key determinant of structural stability in CLC-1. Supporting this hypothesis, myotonic mutant (G523D) at N-terminal of helix O showed the activation at hyperpolarizing membrane potentials with a reversed voltage dependency. However, introducing glutamate at serine residue (S537) at the C-terminal of the helix O on G523D restored WT-like voltage dependency of the common gate and showed proton insensitive voltage dependency. To further validate this significant site, site-specific mutagenesis experiments was performed on V292 that is highly conserved as glutamate in antiporter and closely located to S537 and showed that this area is essential for channel function. Taken together, the results of our study suggest the importance of helix O as the main contributor for stable structure of evolutionary conserved CLC proteins and its key role in voltage dependency of the CLC-1. Furthermore, the C-terminal of the helix O can offer a clue for possible proton involvement in CLC-1 channel. [ABSTRACT FROM AUTHOR]

Voltage-dependent K+ (KV) channels control K+ permeability in response to shifts in the membrane potential. Voltage sensing in KV channels is mediated by the positively charged transmembrane domain S4. The best-characterized KV channel, KvAP, lacks the distinct hydrophilic region corresponding to the S3-S4 extracellular loop that is found in other K+ channels. In the present study, we evaluated the topogenic properties of the transmembrane regions within the voltage-sensing domain in KvAP. S3 had low membrane insertion activity, whereas S4 possessed a unique type-I signal anchor (SA-I) function, which enabled it to insert into the membrane by itself. S4 was also found to function as a stop-transfer signal for retention in the membrane. The length and structural nature of the extracellular S3-S4 loop affected the membrane insertion of S3 and S4, suggesting that S3 membrane insertion was dependent on S4. Replacement of charged residues within the transmembrane regions with residues of opposite charge revealed that Asp72 in S2 and Glu93 in S3 contributed to membrane insertion of S3 and S4, and increased the stability of S4 in the membrane. These results indicate that the SA-I function of S4, unique among K+ channels studied to date, promotes the insertion of S3 into the membrane, and that the charged residues essential for voltage sensing contribute to the membrane-insertion of the voltage sensor domain in KvAP. [ABSTRACT FROM AUTHOR]

The TMEM16 proteins constitute a family of membrane proteins with unusual functional breadth, including lipid scramblases and Cl- channels. Members of both these branches are activated by Ca2+, acting from the intracellular side, and probably share a common architecture, which was defined in the recent structure of the lipid scramblase nhTMEM16. The structural features of subunits and the arrangement of Ca2+-binding sites in nhTMEM16 suggest that the dimeric protein harbors two locations for catalysis that are independent with respect to both activation and lipid conduction. Here, we ask whether a similar independence is observed in the Ca2+-activated Cl- channel TMEM16A. For this purpose, we generated concatenated constructs containing subunits with distinct activation and permeation properties. Our biochemical investigations demonstrate the integrity of concatemers after solubilization and purification. During investigation by patch-clamp electrophysiology, the functional behavior of constructs containing either two wild-type (WT) subunits or one WTsubunit paired with a second subunit with compromised activation closely resembles TMEM16A. This resemblance extends to ion selectivity, conductance, and the concentration and voltage dependence of channel activation by Ca2+. Constructs combining subunits with different potencies for Ca2+ show a biphasic activation curve that can be described as a linear combination of the properties of its constituents. The functional independence is further supported by mutation of a putative pore-lining residue that changes the conduction properties of the mutated subunit. Our results strongly suggest that TMEM16A contains two ion conduction pores that are independently activated by Ca2+ binding to sites that are embedded within the transmembrane part of each subunit. [ABSTRACT FROM AUTHOR]

This work demonstrates a self-adjustable clock generator that closely tracks the voltage dependence of the critical path delay in a microprocessor. A tunable replica circuit (TRC) composed of inverter cells from the standard-cell library performs real-time frequency modulation to reduce the response time to a single cycle, and a digital controller quantizes the clock frequency by selecting appropriate phases of a delay-locked loop (DLL) that generates 16 phases of 2 GHz output. A watchdog unit continuously monitors the clock output to guard against metastability arising from the asynchronous path between the controller and the DLL. The proposed design is implemented in a 28 nm UTBB FDSOI technology and occupies an area of 1120 \mu \text m^2 with 2.7 mW power consumption. The generator has a wide tuning range of 550–2260 MHz at 1 V, functions at 35 MHz at 0.4 V, and can continuously synthesize the clock signal for arbitrary voltage waveforms between 0.4 V and 1 V. [ABSTRACT FROM PUBLISHER]

In this paper is proposed a new balancing three-level three dimensional space vector modulation (B3L-3DSVM) strategy which uses a redundant voltage vectors to realize precise control and high-performance for a three phase three-level four-leg neutral point clamped (NPC) inverter based Shunt Active Power Filter (SAPF) for eliminate the source currents harmonics, reduce the magnitude of neutral wire current (eliminate the zero-sequence current produced by single-phase nonlinear loads), and to compensate the reactive power in the three-phase four-wire electrical networks. This strategy is proposed in order to gate switching pulses generation, dc bus voltage capacitors balancing (conserve equal voltage of the two dc bus capacitors), and to switching frequency reduced and fixed of inverter switches in same times. A Nonlinear Back Stepping Controllers (NBSC) are used for regulated the dc bus voltage capacitors and the SAPF injected currents to robustness, stabilizing the system and to improve the response and to eliminate the overshoot and undershoot of traditional PI (Proportional-Integral). Conventional three-level three dimensional space vector modulation (C3L-3DSVM) and B3L-3DSVM are calculated and compared in terms of error between the two dc bus voltage capacitors, SAPF output voltages and THDv, THDi of source currents, magnitude of source neutral wire current, and the reactive power compensation under unbalanced single phase nonlinear loads. The success, robustness, and the effectiveness of the proposed control strategies are demonstrated through simulation using Sim Power Systems and S-Function of MATLAB/SIMULINK. [ABSTRACT FROM AUTHOR]

In this study, we designed an expression system for the Y. lipolytica yeast, which can be fully efficient in media with non-standard industrial ingredients. Previously, we reported that the mitochondrial Voltage Dependent Anion Channel (VDAC) was a major protein overproduced in the Yarrowia lipolytica yeast in an alkaline (pH = 9.0) culture medium. In this study, the VDAC promoter was cloned and tested using a reporter system based on the LacZ gene. Naturally, the VDAC gene contains an intron located just within the ATG translation initiation codon. The VDAC promoter V2 variant with the intron and V3 variant without the intron were studied. The VDAC-driven clones exhibited high variability of the expression profile. Some clones were more active than the clones induced by the artificial hp4d promoter, when grown in both complete and low-cost industrial ingredient (10% fish and sunflower meal) containing media. The new expression system may greatly expand the range of recombinant producers of feed enzymes and some other types of fodder additives in the Y. lipolytica yeast, appropriate for assimilation of low-cost and non-standard raw material. [ABSTRACT FROM AUTHOR]

Social welfare maximization is used as an objective function to clear day-ahead real power electricity markets with elastic loads. The conventional way is to model loads as voltage independent. This paper investigates behaviour of day-ahead market clearing in the presence of voltage dependent load models at different loading conditions. In a multi-objective framework, different objective functions (load served, generation cost, emission and voltage stability enhancement index) are combined with social welfare so as to examine each function’s behaviour. However, it is observed and demonstrated that the objective functions are either in accord or discord with social welfare at different loading conditions. Therefore, Pareto fronts are obtained to decide the most optimal functioning condition subject to all operating and technical constraints for the judgement making authority. The differential evolution algorithm is applied for single and multi-objective optimization purposes. The model is implemented on IEEE 30 bus system for testing and verification. [ABSTRACT FROM AUTHOR]

Precise measurements of the magnetic-field and gate-voltage dependences of the capacitance of a field-effect transistor with an electron system in a wide GaAs quantum well have been carried out. It has been found that the capacitance minima caused by the gaps in the Landau spectrum of the electron system become anomalously wide when two size-quantization subbands are occupied. The effect is explained by retention of the chemical potential in the gap between the Landau levels of one of the subbands owing to redistribution of electrons between the subbands under a change in the magnetic field. The calculation taking into account this redistribution has been performed in a model of the electron system formed by two two-dimensional electron layers. The calculation results describe both the wide capacitance features and the observed disappearance of certain quantum Hall effect states. [ABSTRACT FROM AUTHOR]

The human VDAC channel exists in three isoforms characterized by high sequence homology and structural similarity. Yet the function and mode of action of hVDAC3 are still elusive. The presence of six surface cysteines exposed to the oxidizing environment of the mitochondrial inter-membrane space suggests the possible establishment of intramolecular disulfide bonds. Two natural candidates for disulfide bridge formation are Cys2 and Cys8 that, located on the flexible N-terminal domain, can easily come in contact. A third potentially important residue is Cys122 that is close to Cys2 in the homology model of VDAC3. Here we analyzed the impact of SS bonds through molecular dynamics simulations of derivatives of hVDAC3 (dubbed SS-2-8, SS-2-122, SS-8-122) including a single disulfide bond. Simulations showed that in SS-8-122, the fragment 1-7 crosses the top part of the barrel partially occluding the pore and causing a 20% drop of conductance. In order to identify other potential channel-occluding disulfide bonds, we used a set of neural networks and structural bioinformatics algorithms, after filtering with the steric constraints imposed by the 3D-structure. We identified other three species, namely SS-8-65, SS-2-36 and SS-8-36. While the conductance of SS-8-65 and SS-2-36 is about 30% lower than that of the species without disulfide bonds, the conductance of SS-8-36 was 40–50% lower. The results show how VDAC3 is able to modulate its pore size and current by exploiting the mobility of the N-terminal and forming, upon external stimuli, disulfide bridges with cysteine residues located on the barrel and exposed to the inter-membrane space. [ABSTRACT FROM AUTHOR]

The plug-in electric vehicle (PEV) is a new atypical load in power systems. In future, PEV load will play a significant role in the distribution grids. This integrated load into the power grid may overload the system components, increase power losses, and affect the voltage profile in the distribution systems. Currently, the constant power load model is most commonly used for the modeling of the electric vehicle (EV) load that considers the EV loads as constant power elements without considering the voltage dependence of the EV charging system. EV load demand cannot be considered as a constant power due to the fact that modeling as a constant power load will not provide accurate information about the behavior of the charging system during the charging process. In this paper, an accurate model representing the realistic behavior of EV load is developed which is based on the ZIP load model with the ZIP parameters established through the realistic EV load data. The proposed model can be used to analyze the true behavior of the EV charger integrated to an electricity grid and determine the impacts of EV charging load on the grid. A realistic charging system was used to test and capture the EV load behavior and extract the coefficients of the EV ZIP load model, which have been verified using computer simulations and laboratory experiments. Additionally, a comparative study between the proposed ZIP load model and the constant power load model was carried out, and the results were verified with the practical EV load data. The results confirm that EV represented using constant power load will not provide the true reflection of the EV load behavior and the EV impacts on the power grid. [ABSTRACT FROM AUTHOR]

This paper presents a new multi-objective day-ahead market clearing (DAMC) mechanism with demand-side reserves/demand response offers, considering realistic voltage dependent load modeling. The paper proposes objectives such as Social Welfare Maximization (SWM) including demandside reserves, and Load Served Error (LSE) minimization. In this paper, energy and demandside reserves are cleared simultaneously through co-optimization process. The paper clearly brings out the unsuitability of conventional SWM for DAMC in the presence of voltage dependent loads, due to reduction of load served (LS). Under such circumstances multi-objective DAMC with demand response offers is essential. Multi-objective Strength Pareto Evolutionary Algorithm 2+ (SPEA 2+) has been used to solve the optimization problem. The effectiveness of the proposed scheme is confirmed with results obtained from IEEE 30 and IEEE 300 bus test systems. [ABSTRACT FROM AUTHOR]

The voltage-dependent anion channels (VDACs), VDAC1, VDAC2, and VDAC3, are pore-forming proteins that control metabolite flux between mitochondria and cytoplasm. VDAC1 and VDAC2 have voltage-dependent gating activity, whereas VDAC3 is thought to have weak activity. The aim of this study was to analyze the channel properties of all three human VDAC isoforms and to clarify the channel function of VDAC3. Bacterially expressed recombinant human VDAC proteins were reconstituted into artificial planar lipid bilayers and their gating activities were evaluated. VDAC1 and VDAC2 had typical voltage-dependent gating activity, whereas the gating of VDAC3 was weak, as reported. However, gating of VDAC3 was evoked by dithiothreitol (DTT) and S -nitrosoglutathione (GSNO), which are thought to suppress disulfide-bond formation. Several cysteine mutants of VDAC3 also exhibited typical voltage-gating. Our results indicate that channel gating was induced by reduction of a disulfide-bond linking the N-terminal region to the bottom of the pore. Thus, channel gating of VDAC3 might be controlled by redox sensing under physiological conditions. [ABSTRACT FROM AUTHOR]

Channelrhodopsins (ChRs) are directly light-gated ion channels that function as sensory photoreceptors in flagellated green algae, allowing these algae to identify optimal light conditions for growth. In neuroscience, ChRs constitute the most versatile tools for the light-induced activation of selected cells or cell types with unprecedented precision in time and space. In recent years, many ChR variants have been discovered or engineered, and countless electrical and spectroscopic studies of these ChRs have been carried out, both in host cells and on purified recombinant proteins. With significant support from a high-resolution 3D structure and from molecular dynamics calculations, scientists are now able to develop models that conclusively explain ChR activation and ion conductance on the basis of chromophore isomerization, structural changes, proton transfer reactions, and water rearrangement on timescales ranging from femtoseconds to minutes. [ABSTRACT FROM AUTHOR]

Bias voltage dependence of tunneling mechanism has been systematically investigated in Co 40 Fe 40 B 20 (2.1 nm)/MgO (2 nm)/Co 40 Fe 40 B 20 (1.7 nm) pseudo-spin valve magnetic tunnel junction deposited using the combination of the pulsed DC unbalanced magnetron and RF magnetron sputtering techniques. Structural investigations revealed polycrystalline and partially (001) oriented growth of CoFeB/MgO(001) MTJ with similar low interface roughness on both side of the MgO barrier. The junction with a 25×25 µm 2 area indicates a giant tunnel magnetoresistance in the order of 505% at room temperature. The magnetoresistance ratio decreases with increasing applied bias voltage ranging from 0.5 to 1.8 V. Reasonable values for barrier thickness and heights were obtained using the combination of Brinkman and Gundlach models, including average barrier height and symmetry. Both barrier parameters and the tunneling mechanism vary in dependence of applied bias voltage. The tunneling mechanism indicates a change from direct to the FN tunneling, especially when reaching high bias voltages. Effect of the tunneling mechanism on the bias dependence of the magnetoresistance was also discussed. [ABSTRACT FROM AUTHOR]

Conventional external quantum-efficiency measurement of solar cells provides charge-collection efficiency for approximate short-circuit conditions. Because this differs from actual operating voltages, the optimization of high-quality tandem solar cells is especially complicated. Here, we propose a contactless method, which allows for the determination of the voltage dependence of charge-collection efficiency for each subcell independently. By investigating the power dependence of photoluminescence decays, charge-separation and recombination-loss time constants are obtained. The upper limit of the charge-collection efficiencies at the operating points is then obtained by applying the uniform field model. This technique may complement electrical characterization of the voltage dependence of charge collection, since subcells are directly accessible. [ABSTRACT FROM AUTHOR]

Serial controllable FACTS devices, such as a Controllable Series Compensator (CSC) and a Static Synchronous Series Compensator (SSSC), can have a significant impact on the voltage stability of an electric power system. This paper presents a mathematical derivation for the voltage dependency of a CSC and a SSSC in a single-load infinitive-bus model. The comparison of the impact of a CSC and a SSSC on the voltage stability in a five-bus system confirmed the new analytical equations. According to theoretical considerations, from the point of view of voltage controllability, each device has its own advantages, but in the case of low voltages or low loads a SSSC is superior to a CSC. [ABSTRACT FROM AUTHOR]

If determination of location and size of Distributed Generation (DG) are applied accurately, the DG's ability will improve the network situation and reduce operation costs. In this paper, various market conditions are considered to maximize the benefit of DG's presence and make a trade off among advantages of DG, network situation, and Distribution Company (DISCO) owners. To determine the optimal location and size of DG, two methods of the cost minimization and the nodal pricing are combined. In addition to evaluating the impact of parameters such as variation of energy price and load on objective function, effect of these parameters on location and size of DG is considered. To confirm the results, impact of loads which are dependent on voltage and variation of the power factor of the DG units is applied and then effect of power factor on optimal location and size of DG is shown. A method is proposed for convergence of different results which is caused by different power factors. To observe long-term impact of the DG's presence in the network, a load growth for five years is considered annually. Study is carried out on IEEE30 bus test circuit. [ABSTRACT FROM AUTHOR]

Voltage dependent anion channels (VDACs) are the most abundant proteins in the outer mitochondrial membrane. Although they are essential in metabolite exchange, cell defense and apoptosis, the molecular mechanism of these VDAC-mediated processes remains elusive. Here we review recent progress in terms of VDACs' structure and regulation, with a special focus on the molecular aspects of gating and the interaction with effector proteins. [ABSTRACT FROM AUTHOR]

This paper deals with a control method that adapts the dc bus voltage of electric traction systems using permanent-magnet synchronous machine (PMSM) fed by bidirectional $Z$-source inverter (ZSI) or other improved topologies. This control allows reducing both the overestimation of the dc bus voltage and losses in the inverter. The sliding-mode control (SMC) method is used to control the $Z$-source converter, whereas flatness-based control is proposed to drive the actuator and generate the peak dc bus voltage reference. Flatness-based control is chosen because the actuator transients are well mastered. Extra shoot-through zero inverter states are inserted by means of implemented algorithm on a space-vector-modulation (SVM) scheme. Different short-circuit strategies are studied and compared according to constraint criteria. Both simulation and experimental results are presented and discussed to validate the proposed voltage adaptation strategy and the improvement on global efficiency. [ABSTRACT FROM AUTHOR]

A three-phase three-level bidirectional ac-dc neutral-point-clamped converter (3 L-NPC) based on one-cycle control (OCC) is proposed in this study. It ensures that the 3 L-NPC converter operates stably during inverting mode of operation. A neutral point potential regulator is also presented which adds a dc offset to the three-phase modulating signals to nullify the deviation in the neutral point potential. First, a one-cycle controlled (OCC) 3 L-NPC converter which requires the sensing of instantaneous phase voltages of the utility is presented. Subsequently, a modified version of the OCC-based 3 L-NPC converter which does not requires sensing of the instantaneous phase voltages is proposed. The modified OCC-based 3 LNPC estimates instantaneous phase voltages of the source from the pulse width modulation (PWM) switching sequence of the converter. The viability of the schemes is confirmed through a detailed simulation and experimental studies. [ABSTRACT FROM AUTHOR]

We show DNA origami nanopores thatrespond to high voltages bya change in conformation on glass nanocapillaries. Our DNA origaminanopores are voltage sensitive as two distinct states are found asa function of the applied voltage. We suggest that the origin of thesestates is a mechanical distortion of the DNA origami. A simple modelpredicts the voltage dependence of the structural change. We showthat our responsive DNA origami nanopores can be used to lower thefrequency of DNA translocation by 1 order of magnitude. [ABSTRACT FROM AUTHOR]

This paper presents a detailed theoretical analysis and performance assessment of the capacitor voltage balancing strategies for staircase modulated modular multilevel converters (MMC) in terms of the algorithm structures, voltage balancing effect, and switching frequency. A constant-frequency redundancy selection (CFRS) method with minimal switching loss is proposed and the function realization of specific modules of the algorithm is given. This method is simple and efficient in both switching frequency and regulation capacity. Laboratory results show very good agreement with the theoretical analysis and numerical simulations. [ABSTRACT FROM AUTHOR]

Partial obstruction of the small intestine causes obvious hypertrophy of smooth muscle cells and motility disorder in the bowel proximate to the obstruction. To identify electric remodeling of hypertrophic smooth muscles in partially obstructed murine small intestine, the patch-clamp and intracellular microelectrode recording methods were used to identify the possible electric remodeling and Western blot, immunofluorescence and immunoprecipitation were utilized to examine the channel protein expression and phosphorylation level changes in this research. After 14 days of obstruction, partial obstruction caused obvious smooth muscle hypertrophy in the proximally located intestine. The slow waves of intestinal smooth muscles in the dilated region were significantly suppressed, their amplitude and frequency were reduced, whilst the resting membrane potentials were depolarized compared with normal and sham animals. The current density of voltage dependent potassium channel (KV) was significantly decreased in the hypertrophic smooth muscle cells and the voltage sensitivity of KV activation was altered. The sensitivity of KV currents (IKV) to TEA, a nonselective potassium channel blocker, increased significantly, but the sensitivity of IKv to 4-AP, a KV blocker, stays the same. The protein levels of KV4.3 and KV2.2 were up-regulated in the hypertrophic smooth muscle cell membrane. The serine and threonine phosphorylation levels of KV4.3 and KV2.2 were significantly increased in the hypertrophic smooth muscle cells. Thus this study represents the first identification of KV channel remodeling in murine small intestinal smooth muscle hypertrophy induced by partial obstruction. The enhanced phosphorylations of KV4.3 and KV2.2 may be involved in this process. [ABSTRACT FROM AUTHOR]

Abstract: Niobium doped indium tin oxide (ITO:Nb) thin films were fabricated on glass substrates by RF magnetron sputtering from one piece of ceramic target material at room temperature. The bias voltage dependence of properties of the ITO:Nb films were investigated by adjusting the bias voltage. Structural, electrical and optical properties of the films were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), UV–visible spectroscopy, and electrical measurements. XRD patterns showed a change in the preferential orientations of polycrystalline crystalline structure from (222) to (400) crystal plane with the increase of negative bias voltage. AFM analysis revealed that the smooth film was obtained at a negative bias voltage of -120V. The root mean square (RMS) roughness and the average roughness are 1.37nm and 1.77nm, respectively. The films with the lowest resistivity as low as 1.45×10−4 Ωcm and transmittance over 88% have been obtained at a negative bias voltage of −120V. Band gap energy of the films, depends on substrate temperature, varied from 3.56eV to 3.62eV. [Copyright &y& Elsevier]

TRPM8 is a voltage-dependent cation channel additionally gated by cold temperatures, menthol, and icilin. Stimulation by the chemical agonists is at least in part mediated by a conserved sequence motif in transmembrane segment S3. Based on molecular dynamics simulation studies for TRPM8 a gating model was recently developed which predicts a direct electrostatic interaction between S3 and S4. Here, we performed charge reversal mutations to pinpoint possible interactions of the putative S4 voltage sensor with S3. The charge reversals R842D, R842E, and D835R in S4 prevented channel glycosylation and function, indicating a deficient insertion into the plasma membrane. The mutations R842D and R842E were specifically rescued by the reciprocal charge reversal D802R in S3. The alternative charge reversal in S3, D796R, failed to compensate for the dysfunction of the mutants R842D and R842E. Remarkably, the double charge reversal mutants R842D + D802R and R842E + D802R retained intrinsic voltage-sensitivity, although the critical voltage sensor arginine was substituted by a negatively charged residue. Likewise, the insertion of three additional positively charged residues into S4 did not crucially change the voltage-sensitivity of TRPM8 but abolished the sensitivity to icilin. We conclude that S4 does not play a separate role for the gating of TRPM8. Instead, the cooperation with the adjacent segment S3 and the combined charges in these two segments is of general importance for both channel maturation and channel function. This mechanism distinguishes TRPM8 from other voltage-dependent cation channels within and outside the TRP family. [ABSTRACT FROM AUTHOR]

A Cúk converter operating in discontinuous capacitor voltage mode (DCVM) is an inherent power factor correction converter. A reduced-order switch-network model of a Cúk converter in DCVM is developed, which is valid for both dc–dc and ac–dc applications. The model can be used for controller analysis and design. Moreover, a fast dynamic response controller is proposed, which is an integration of a switching-frequency control unit and a proportional-integral (PI) controller. The PI controller is in charge of duty ratio adjustment. In the proposed controller, unlike conventional PI controllers, switching frequency is no longer fixed and varies as load changes. The switching-frequency control unit reacts much faster than the PI controller and instantly compensates for the output voltage in case of drastic load change, thus significantly improving the transient response. Furthermore, the proposed control scheme keeps the switch voltage stress constant, which eases switch selection and improves converter reliability. [ABSTRACT FROM PUBLISHER]

The modular multilevel converter (MMC) is a potential candidate for medium/high-power applications, specifically for high-voltage direct current (HVDC) transmission systems. One of the technical challenges associated with the control of an MMC is to carry out the submodule (SM) capacitor voltages balancing task without imposing any unnecessary switching transition among the SMs. This paper develops a general framework for the capacitor voltage balancing of an MMC. Based on the developed framework and with the objective of reducing the unnecessary switching transitions among the SMs, three capacitor voltage-balancing strategies are proposed and investigated: 1) a slow-rate balancing strategy based on the conventional sorting method; 2) a hybrid balancing strategy which combines a predictive method with the conventional sorting method; and 3) a fundamental-frequency balancing strategy. Performance of the proposed strategies for a point-to-point 21-level MMC-based HVDC system is evaluated based on time-domain simulation studies in the PSCAD/EMTDC software environment. The reported study results demonstrate the capability and tradeoffs of the proposed strategies to reduce the number of switching transitions and, consequently, the MMC losses, under various conditions. [ABSTRACT FROM AUTHOR]

Energy capacity of a voltage-dependent capacitor is investigated and defined. An equation for the calculation of energy capacity of the MOSFET's parasitic capacitance is formulated. The defined energy capacity of a voltage-dependent capacitance can be used to calculate switching loss of resonant switches by simply calculating the energy transferred into or retrieved from the MOSFET. The validity of the proposed formula is verified by computer simulation. The discrepancy between energy capacity of the MOSFET's parasitic capacitance calculated from the formulated equation and that calculated from the results of computer simulation is negligible. Computer simulation is also used to validate the proposed switching-loss calculation technique. [ABSTRACT FROM AUTHOR]

In this paper, motivated by the driving mechanism of a putt-putt toy boat, we explore the feasibility to propel a microsubmarine using a thermally oscillatory approach, which only requires a simple design and does not involve any complicated propulsive systems. We investigate the design, fabrication, actuation and horizontal motions of the corresponding microsubmarines. Based on the understanding gained through preliminary tests on two manually fabricated putt-putt boats, we designed and fabricated the prototype of a microsubmarine. Similar to a putt-putt boat, the prototype also uses a thermally oscillatory process for propulsion. In a cyclic period of this process, due to the expansion and shrinkage of a vapor bubble inside the reservoir of the submarine, liquid is first ejected outside and then sucked into the reservoir. Due to the difference in liquid flow directions between ejection and suction stages, a thrust is produced to propel the submarine. At an applied voltage of 16 V and pulse frequency of 100 Hz, the submarine was found to have the highest speed of 1.8 mm s−1 and longest travel distance of 12.6 mm. The corresponding thrust was estimated to be 67.6 nN. [ABSTRACT FROM AUTHOR]