High Power Conditions Research Articles

Effects of high and low power on the visual encoding of faces

ABSTRACT The experience of power is typically associated with social disengagement, yet power has also been shown to facilitate configural visual encoding – a process that supports the initial perception of a human face. To investigate this apparent contradiction, we directly tested whether power influences the visual encoding of faces. Two experiments, using neural and psychophysical assessments, revealed that low power impeded both first-order configural processing (the encoding of a stimulus as a face, assessed by the N170 event-related potential) and second-order configural processing (the encoding of feature distances within configuration, assessed using the face inversion paradigm), relative to high-power and control conditions. Power did not significantly affect facial feature encoding. Results reveal an early and automatic effect of low power on face perception, characterized primarily by diminished face processing. These findings suggest a novel interplay between visual and cognitive processes in power’s influence on social behavior.

PtSe2 phototransistors with negative photoconductivity

Platinum diselenide (PtSe2) is one of the most studied materials of the emerging group-10 transition-metal dichalcogenides. We investigate the electrical conduction and the photoconduction of PtSe2 ultrathin films exploited as the channel of back-gated field-effect transistors. The channel resistance decreases with the rising temperature and shows that the films have semiconducting behaviour. The gate modulation confirms a p-type conductivity with field-effect mobility up to 30 cm2/(Vs). Under exposure to the radiation from a super-continuous white light source, a reduction of the PtSe2 electrical conductivity (negative photoconductivity) is observed in low vacuum, while a positive photoconductivity emerges only under high-power illumination conditions. Although, the positive photoconductivity arises from conventional photoconductive effect, the negative photoconductivity can be explained as the combination of the photogating effect caused by charge accumulation in the SiO2 dielectric and the photo-induced desorption of adsorbates.

Start-up characteristics for the test facility of a prototype sodium heated OTSG

The test facility of the prototype sodium heated once-through steam generator (OTSG) is used to verify the accuracy and reliability of the design for the sodium heated OTSG. Besides, according to the test data, the structure and parameters of steam generator can be improved. In this paper, the start-up mode of the test facility of the prototype sodium heated OTSG was pre-analyzed by using the modified RELAP5 MOD4.0. Two kinds of modes to reach the steady state, one is step change mode the other is linear change mode. These two modes are adopted respectively to analyze the thermal hydraulic characteristics of prototype sodium heated OTSG under different conditions. The results show that the step change mode can be used to reduce the time of reaching steady state in low power starting. When the loop is running under high power condition, step change mode can reduce the temperature raise rate and increase the safety of the system.

Temperature optimization for AlGaN/GaN HEMT with the etched AlGaN layer based on 2-D thermal model

When the AlGaN/GaN HEMT is working for a long time under the high-power and high-temperature conditions, the internal heat will reduce its reliability. Here, the author first proposed a 2-D temperature distribution model to explain the mechanism of internal charge modulation to reduce the junction temperature of AlGaN/GaN HEMT. The etched AlGaN layer affects the channel 2DEG distribution and a new hot spot is generated in the thermal field, which effectively reduces the temperature and gets a more uniform temperature distribution. A quantitative analysis of the temperature model has been given to describe the effect of structure parameters on temperature optimization, and deeper etching depth is beneficial to reduce the junction temperature. The model is verified through simulation results and experimental tests, which prove its applicability. It is concluded that this model can effectively describe the temperature optimization of AlGaN/GaN HEMTs with the gate-edge etching technique.

Internal diameter HVOAF thermal spray of carbon nanotubes reinforced WC-Co composite coatings

A novel process, relatively fast and scalable compared to existing ones, has been used to incorporate carbon nanotubes (CNT) 0.5 wt% onto commercial WC-Co thermal spray powder. Nano enabled WC-Co/CNT coatings were obtained by internal diameter HVOAF thermal spray at three different spray powers (48, 41 and 34 kW). A general increase in microhardness and decrease in fracture toughness has been found when adding CNT. Also, carbide retention index upon spray was improved by lowering the process temperature and adding CNT, reaching 99% in the low power case with CNT. The interplay of these features has shown an overall better wear performance in the medium power case without CNT; in fact, the addition of CNT has improved the wear performance at high power conditions (reduction of coefficient of friction by half) while reducing the wear performance in medium and low power. A tailored choice of CNT concentration can offer enhanced mechanical or tribological properties according to the needs for different applications. This novel process for nanoparticles incorporation opens the way for the production of large batches of readily usable nano-enabled powder.

WITHDRAWN: An implementation of SoC-based earth scanning system using ultrasonic encoded transmission

• In this research work an advanced SoC based earth scanning module is designed based on Verilog language, this design is verified on zynq-7000 board. • Existing models do not have efficient material scanning methods; therefore, an advanced scanning model is necessary. • This design successfully identifies the material to be gold, water, petrol and coal. • The conventional methods worked on high power and low performance conditions but the proposed method improves the power consumption by 73.24%,area by 72.24% and are equally economical. • An advanced System-on-Chip (SoC) architecture is designed to identify different valuable minerals embedded in the earth's surface in this paper. An advanced System-on-Chip (SoC) architecture is designed to identify different valuable minerals embedded in the earth’s surface in this paper. Materials such as gold, diamond, petrol, and coal generate high revenues for developing and established nations. Therefore, to identify different materials, an efficient electronic device is designed in which scanning becomes an important parameter. This investigation is performed by an SoC-based ultrasonic module designed using Xilinx Vivado and verified on the ZYNQ-7000 FPGAboard. This architecture consists of a code generation unit, modulator, delays, emitter, demodulator, correlator, detector, and receiver. These modules are developed using Verilog HDL and deliver output on high-level processing screen. The experimental results outperform the conventional methodology with respect to reduced power consumption and area, this model is compared with existing methods to identify the operational performance. This SoC based ultrasonic scanning method improves the power consumption by 73.24% and area 72.24%.

How Social Power Affects the Processing of Angry Expressions: Evidence From Behavioral and Electrophysiological Data.

With the help of event-related potentials (ERPs), the present study used an oddball paradigm to investigate how both individual and target power modulate neural responses to angry expressions. Specifically, participants were assigned into a high-power or low-power condition. Then, they were asked to detect a deviant angry expression from a high-power or low-power target among a series of neutral expressions, while behavioral responses and electroencephalogram (EEG) were recorded. The behavioral results showed that high-power individuals responded faster to detect angry expressions than low-power individuals. The ERP analysis showed that high-power individuals showed larger P3 amplitudes in response to angry expressions than low-power individuals did. Target power increased the amplitudes of the P1, VPP, N3, and P3 in response to angry expressions did, but decreased the amplitudes of the N1 and N170 in response to angry expressions. The present study extended previous studies by showing that having more power could enhance individuals’ neural responses to angry expressions in the late-stage processes, and individuals could show stronger neural responses to angry expressions from high-power persons in both the early‐ and late-stage processes.

Investigation into the Selection of Dielectric Material using MCDM Methodologies for MEMS Switches with High Power

This paper presents MCDM techniques (TOPSIS and VIKOR) for determining the optimum dielectric material for MEMS technology based high power capacitive switches. These techniques are used for picking the best material from a given set of materials under some given criterion. The capacitance ratio and dielectric leakage current which are important parameters in obtaining the good RF-response of a switch have been taken into consideration along with other parameters like thermal expansion, heat dissipation and melting point for choosing the best material. Under high power condition, chosen material must have lowest value of TCE, highest possible thermal conductivity, highest melting point, along with highest value of electrical resistivity and relative permittivity for good RF response. The result of both the methods shows that AlN is the best material followed by TiO2. Kindly check and confirm the inserted country name in affiliation 1 is correcly identified. Yes, It is correct.

Laser-diode-array side-zigzag-pumped polygon thin-disk laser

The high-average-power diode-pumped solid-state laser is one of the main research directions in the field of international laser technology, and has major applications in the fields like space exploration, precise detection, fusion research, etc. Under high-power pumping conditions, the conventional rods or slabs are not conducive to effectively removing waste heat. And the thermal effect causes the quality of the laser beam to deteriorate, which limits the further increase of the output power. In this article, the polygonal Nd: YAG thin disk is taken as a gain medium for the laser, and experiments verify that the side pumping method can obtain a higher output power of the all-solid-state pulsed laser while ensuring high beam quality. The gain medium is a regular pentagonal Nd: YAG thin disk with a side-cut-angle of 45°, the crystal thickness is 1.5 mm, and the diameter of the inscribed circle on the front face is 16 mm. Five laser diode arrays are placed symmetrically around the disk, and the pump surfaces are parallel to the sides of the disk. The pump laser propagates along the zigzag path between the upper and lower surface of the disk, thus improving the absorptive efficiency and pump uniformity. Through the optimization study of its gain characteristics and optical characteristics, the high-efficiency high-uniform pumping is achieved. Along the pump light coupling transmission path, the fast-axis collimator is used to control the beams in the fast-axis direction to be nearly parallel, and the large-area pump light is compressed through the coupling structure of cylindrical lens and light guide to match the size of the thin disk, and the pump coupling efficiency measured experimentally is 97%. When the Nd<sup>3+</sup> doping concentration in the crystal is 0.3 at.%, the gain medium absorptive efficiency is 87%, and the root mea squared pump absorptive distribution uniformity in the gain medium is 3.21%. The fluorescence distribution of the gain medium is in good agreement with the simulated data. When the pump energy is 2.2 J, a laser output with an energy of 0.85 J is obtained, and optical-to-optical efficiency and slope efficiency are 38.8% and 40.1%, respectively. The single pulse energy stability is 2.7%(RMS) at 1 Hz frequency. In the stable cavity, the beam quality <i>β</i> - factor is measured to be about 10.

Polarization switching behavior of (Pb,Nb)(Zr,Sn,Ti)O3 ferroelectric ceramics under high-power pulse condition in microsecond scale

In the present work, the polarization switching of polycrystalline (Pb,Nb)(Zr,Sn,Ti)O3 (PNZST) ferroelectric (FE) ceramics in microsecond scale was investigated by pulse switching experiment. Typical switching current similar to that of FE single crystal and thin films was observed in PNZST ceramics, directly proving the completion of the switching process in microsecond scale. The increase of switching current and decrease of switching time with increasing electric field and temperature were confirmed and explained by the acceleration of the nucleation and growth rate of domains. However, the distortion of the pulse voltage also results in difficulty to analyze the switching current via Merz’s equation, which was usually neglected in previous works. In addition, the pulse switching dynamic is also found to be a current-limiting process and strongly depends on the circuit parameters. By increasing the resistance of the in-series resistor, the switching process will be hindered, leading to the decrease of switching current and longer switching period. More importantly, the curve of polarization versus electric field (P–E) was obtained by the switching current and a distinct difference was observed compared with the 0.1 Hz P–E curve. The above results prove the possibility of using PNZST ceramics in high-power pulse technology and will give some important guidance for the designation of FE devices.

Flexible quasi-solid-state lithium-ion capacitors employing amorphous SiO2 nanospheres encapsulated in nitrogen-doped carbon shell as a high energy anode

Lithium-ion hybrid capacitors (LICs) take the advantage of simultaneous high energy – power output, and become increasingly important for next generation applications. Developing a high performing LICs with high energy-power-cycle combination remains a significant challenge due to low capacity intercalation electrodes, and kinetically sluggish alloying type electrodes. A strategy employing fast pseudocapacitive lithium ion storage in high-capacity alloying type anode, rather than a bulk storage, can output kinetically superior LICs with high energy even at high power conditions. Herein, we demonstrate a highly interconnected 3-dimensional (3D) SiO2 nanospheres embedded Nitrogen-doped carbon shell with fast lithium ion storage kinetics as high performing anode for LICs. As a result, LIC with a high energy (139 Wh kg−1), high power density (42 kW kg−1), and super stability (20,000 cycles) is obtained, outperforming previously studied alloying type metal oxide and sulfide anodes. A flexible LICs is further demonstrated which shows good stability under different bending conditions. The current research promotes the practical utilization of earth-abundant material as a high capacity and high rate electrode for the next-generation flexible and wearable devices.

Study of Cu Replacement in Na2Ti1-XTMXO3 Na-Rich Cathode Material for High Capacity and Superior Stability

Sodium ion batteries are considered as a cost effective and promising alternative to lithium ion batteries for next generation large scale energy storage applications. However, the sluggish intercalation kinetics and poor stability plagues the efficient applications.[1] Recently sodium rich cathode materials are emerging as a promising system to retain high specific energy with improved durability. Benefiting from the stabilizing property of other transition metal [TM = Cu, Cr] , the same is used as a substitute in Ti site and improved stability have been achieved. [2] In this work, we developed a high performing doped cathode of Sodium Titanium Oxide (Na2TiO3) as a battery positive electrode. The highly favorable architecture in both the electrodes showed an enhanced capability towards ion storage. A high energy retention at high power condition along with high stability have been achieved.

Ignition, efficiency and emissions of RP-3 kerosene in a three-staged multi-injection combustor

In this work, a three-staged multi-injection based on the triple-swirler technique was proposed and investigated, which can broaden the engine envelope than a two-staged fuel supply scheme. The fuel can be split into three portions according to the combination of different injectors. Injection-1 means that only injector-1 supplies fuel, while Injection-1 + 2 means that injector-1 and injector-2 supply fuel simultaneously. The spark ignition performance, combustion efficiency, and exhaust emissions by using RP-3 kerosene are analyzed and compared with different fuel injection modes. The excellent ignition performance is achieved by using injection-1 with the ignition fuel-air ration is 0.008, whereas the other injection modes perform relatively poorly. The efficiency and exhaust emissions curves achieved by injection-1 + 2 and injection-1 + 3 intersect, where the overall equivalence ratio is about 0.25. When the overall equivalence ratio exceeds this critical value, the combustion efficiency of RP-3 kerosene achieved by using injection-1 + 3 can be up to 1% higher than injection-1 + 2. Furthermore, the optimal fuel supply scheme by the three-staged multi-injection technology is achieved: injection-1 is used for spark-ignition, injection-1 + 2 for low power conditions (overall equivalence ratio is less than 0.25), and injection-1 + 3 for high power conditions.

Elemental Mapping of Entire Thick Film Electrodes By Laser-Induced Breakdown Spectroscopy

Next generation lithium-ion batteries require new research and development in the field of high energy / high power materials and concepts regarding cell design and electrode architectures. Particularly for automotive applications, the identification and control of degradation processes are main issues for maintaining long cell life-time and high safety standards. One promising approach for the visualization of elemental composition in lithium-based battery systems is the appliance of laser-induced breakdown spectroscopy (LIBS), which enables a rapid screening of materials, e.g., entire electrodes. So far, this diagnostic approach is being used for semi-quantitative investigation of battery components. However, at KIT, a full-quantitative analysis was developed for characterizing the lithium distribution and concentration as function of state-of-charge. From technical point of view, recording of three-dimensional (3D) elemental profiles, verification of material stoichiometry or even a quality controlled analysis during continuous roll-to-roll production can be easily performed under standard ambient conditions. In this work, we will focus on establishing LIBS for quantitative chemical mapping of entire electrodes after electrochemical cycling. Electrodes with variation in local porosity and tortuosity have been prepared by mechanical loading, while fs-laser radiation was applied for the development of 3D electrode architectures. First of all, on anode side, an increased tortuosity was realized by separator defects, consciously placed in coin cells during cell assembly. Simply saying, the separator sheet was blocked on selected regions in order to investigate post-mortem the possible emergence of local lithium plating. Secondly, compression molding was locally performed for studying lithium distribution in cathodes showing a sudden change in porosity. Two types of geometrical arrangements were applied for the formation of low and high porosity regions. Briefly, non-uniformities in porosity and tortuosity affect the electrochemical performance, especially at charging and discharging currents equal or above 1C. In an early stage of electrochemical cycling, a significant drop in specific capacity could be observed for both types of electrodes. Yielded from quantitative LIBS data, an enhanced local lithium concentration could be detected at the electrode surface, located in the neighborhood of separator defects (for anodes) and at the interface between low and high porosity regions (for cathodes). In contrast, fs-laser generated micro-pillars provide new pathways for Li+-ions, leading to a tremendous boost in diffusion kinetics. Thus, an enhanced specific capacity was observed for cells with laser-structured electrodes during high power conditions. Chemically proven by LIBS, a slight enrichment of intercalated lithium could be detected along the contour of each laser-generated micro-pillar, which indicates that laser-structuring can fulfill the requirements for next generation batteries, providing both, a contemporaneous high energy- and power density on battery-level. In summary, a full screening of entire electrodes achieved from post-mortem LIBS studies will be presented, based on influencing factors such as porosity, tortuosity, and laser-assisted surface modification.

Fuel placement and atomization inside a gas-turbine fuel injector at realistic operating conditions

The atomization process and fuel placement inside a gas turbine fuel injector are investigated at realistic operating conditions to understand the role of individual flow processes and hardware components. A high pressure, high temperature spray test facility is developed that can simulate a wide range of aero-engine operating conditions. The fuel injector is a swirl cup - dual orifice nozzle combination which is used in the rich dome combustors of various aero-engines. The internal flow field is captured using time-resolved laser induced fluorescence imaging and phase Doppler interferometry measurements. A stage-wise characterization is adopted to track the spray formation as the flow evolves through the swirl cup. The fuel placement at the cup exit is mainly decided by pilot nozzle spray characteristics and the relative momentum exchange between the gas and liquid phases. At the swirl cup exit, two class of droplets are formed: (1) droplets originated directly from the pilot nozzle, which are convected downstream by the primary air swirl, (2) droplets originated from the rim, which are atomized by the shear layer. The relative percentage of these two droplet classes depends on the pilot nozzle operation at low and high power conditions. The effect of primary spray and wall-filming are minimal towards improving the atomization. In both low and high power operating cases, the counter-rotating shear layer interactions are identified as the major mechanism that is improving the atomization process in swirl cup.

Growth of ZnO nanostructures: Cones, rods and hallow-rods, by microwave assisted wet chemical growth and their characterization

ZnO nanostructures were grown by microwave assisted wet-chemical growth, at different microwave powers and for different growth durations. The grown nanostructures were analysed for their morphological, structural, compositional and optical characteristics. The total microwave power per growth run (product of microwave power and growth duration, with units in watt-min), has a linear relationship with most of the characteristics of the grown ZnO nanostructures. It is shown that by altering the microwave power per growth run, the morphology of the individual ZnO nanostructure can be changed from cones with hexagonal cross section, to faceted hexagonal nanorods, to hollow hexagonal nanorods. It is observed that, while the fast growth rate along the high energy polar faces (0001) and (000Ī) of ZnO is the reason behind the formation of one dimensional ZnO structures (cones and rods), the process of formation of hallow ZnO rods is due to further etching/material-removal from the tip of the rods, at high microwave power conditions at long growth durations.

Influence of powder particle morphology on properties of Al-10Si-0.4Mg alloy fabricated by high-power and high-speed conditions of laser powder bed fusion process

Influence of powder particle morphology on properties of Al-10Si-0.4Mg alloy fabricated by high-power and high-speed conditions of laser powder bed fusion process

Modeling and Performance Evaluation of Inductive Couplers for Pulsed Current Injection

Pulsed current injection (PCI) is an important conducted susceptibility testing technique. In several related standards, the short-circuit current waveforms of the pulse generators are defined and the coupling methods are mentioned, whereas the performance of the couplers and the injected electrical quantities have not been clearly defined. Therefore, the couplers with different performance criteria would lead to various injected electrical quantities and consequently rather different experimental effects. This article focuses on modeling and quantitatively evaluating the performance of inductive couplers. The key issue in modeling is how to measure the frequency-dependent characteristics of ferrite cores under high-power operating conditions (up to several kA); therefore, an impulse injection method is proposed and validated by a 400-kV pulse generator with the rise time of 5 ns to measure the frequency-dependent characteristics of ferrite cores. The validation test confirms that the bandwidth of the modeling procedure can cover the bandwidth of interest for PCI tests. The criteria of performance evaluation for inductive couplers are proposed in frequency domain as well as in time domain. In addition, the criteria are compared for two inductive couplers with different ferrite materials, which shows that the criteria are not only significant in comparing and selecting couplers quantitatively, but also of critical importance in the design phase.

Parameter optimization of the high-power laser powder bed fusion process for H13 tool steel

In this study, process parameter optimization was performed for the powder bed fusion of H13 tool steel under low- (400 W) and high-power (1000 W) conditions using the SLM 280HL machine. The effects of process parameters such as the laser power, scan speed, and hatching pitch on the density and microstructure of the as-built H13 tool steel were investigated. The specimen density was found to be slightly lower under the high-power condition than that under the low-power condition. Electron backscattering diffraction analysis identified that the as-built specimens showed a prolonged columnar microstructure in the build direction under the low-power condition. In contrast, for the specimens fabricated using the hull-core method under the high-power condition, the hull and core parts showed prolonged columnar and equiaxed microstructures, respectively. Phase distribution images indicated that the microstructures of the as-built specimens under the low- and high-power conditions contained martensite (bcc) and austenite (fcc) with a grain size of approximately 1 μm. Thus, it was found that the specimen density achieved using the 400-W laser is higher than that achieved using the 1000-W laser; moreover, the microstructure of the as-built specimen using the 400-W laser is different from that using the 1000-W laser.

Comprehensive sizing and optimization method for series-hybrid unmanned convertiplane

This paper presents a novel sizing and optimization approach for the emerging series-hybrid unmanned convertiplane, which can be used to translate the top-level design requirements into the design parameters corresponding to the optimal power supply strategy and minimum total takeoff weight. The method comprehensively considers the design constraints in the rotor, fixed-wing, and transition modes, and pays special attention to the characteristic response of Series Hybrid Electric System (S-HES) in complex application scenarios, especially the coupling of battery power, energy, and state-of-charge under high-power discharge conditions, the variation of fuel economy, and the adjustment of power supply strategy. With proposed method, it’s possible to rapidly explore the design space in the initial design stage and find out the optimal design results with high confidence. A case study was proposed to verify the approach. The results reveal the particularity of convertiplane in terms of power requirements, and prove the necessity to consider detailed S-HES characteristic responses during parameter determination. The optimal design parameters were obtained through the hybrid control parameter optimization, which verified the effectiveness of proposed method. Possible errors and corresponding correction methods were also presented.