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A terahertz integrated amplifier circuit packaged inside a WR-3.4 waveguide is presented. The circuit, fabricated using 250-nm InP technology, contains three amplifier chains each connected to its own input and output waveguide transition pairs. The size of the transition is minimised for the chip to properly fit inside the standard waveguide. The assembled waveguide module shows the peak amplifier gain of 13 dB and 3-dB bandwidth of 32 GHz as its gain is 6.2 dB less than that of an on-wafer amplifier measured using RF probes. The maximum measured output power from the module is 6.5 dBm at 260 GHz compared to 1.4 dBm from single on-wafer amplifier chain. [ABSTRACT FROM AUTHOR]

Aim of the study was to investigate the relationship between lower body rate of force development and lean body mass, with competitive shot-put throwing performance in female shot-putters using the linear style. Seven female shot-put athletes (age: 24.4 ± 4.2yrs, body height: 172.8 ± 5.2cm, body mass: 93.3 ± 10.5kg, 4.4 ± 2.0 years of competition experience), who qualified for the final of the shot-put event of the national indoor championship, participated in the study. Three days after the national event, they visited the laboratory to perform maximal isometric leg press for the measurement of the rate of force development (RFD), and maximal countermovement jumps (CMJ), while body composition (dual x-ray absorptiometry) was also evaluated. Shotput performance was recorded from the official results during the national event. Close correlations were found between shot-put performance during competition and RFD between 100-250ms, maximum leg press isometric force, and CMJ power (r: 0.766 - 0.913, p < 0.05). Close correlations were also found between shot-put performance and total (r: 0.932, p < 0.005) and trunk (r: 0.885, p < 0.005) lean body mass (LBM). Lower extremities' LBM was correlated with CMJ max power and RFD between 0-250ms from the onset of muscle contraction (r: 0.834 - 0.905, p < 0.05). These results suggest that monitoring leg press rate of force development, lean body mass and countermovement jumping power may provide important information about performance in female shot-putters who compete with the lineal style. [ABSTRACT FROM AUTHOR]

The influences of VVT on engine power performance were well summarized in previous studies from various aspects. However, most of the previous investigations were qualitative analysis and focused on the total effects of VVT without decoupling the influence factors. The primary cause is due to lack of an effective mathematic model to predict the IMEP of VVT engine. In this study, an approach to detect the VVT signals of engine was proposed, and the influence factors of power performance of VVT engines were quantitatively studied. The fundamental relationships among IMEP and its influencing parameters, i.e., intake density, intake VVT, RGF and thermal efficiency, were decoupled and the governing equation of IMEP was derived with the influences of VVT considered, the calculated results through which are in good agreement with tested data. Results indicate that, IMEP is directly proportional to effective cylinder volume at IVC timing and inversely proportional to RGF. The change rate of RGF influence coefficient is almost three times as that of RGF, and the combined effects of these parameters on IMEP equals the product of the coefficients of four influence factors. All these extended engine thermodynamics and provided theory basis for improving VVT engine's power performance. [ABSTRACT FROM AUTHOR]

The primary objectives of this work were to devise an effective subjective evaluation method for automobile power performance based on regression analysis combined with the analytic hierarchy process (RA-AHP) and to propose a reliable, convenient approach for establishing an evaluation system for automobile power performance. To validate this method, four vehicles were selected, and 30 drivers completed a test drive on a selected route. A five-level Likert questionnaire was designed to subjectively evaluate automobile power performance. The test data were then compiled and used to establish an evaluation system based on the RA-AHP method, and the results from the evaluation system were compared with the vehicle sequence results from the drivers. The comparison showed that the results were the same and thus verified the feasibility of the RA-AHP method. This method is suitable for automobile companies to establish a subjective evaluation system of automobile power performance and can also be used in other fields to build a comprehensive evaluation system. [ABSTRACT FROM AUTHOR]

The platform pitching motion of the Offshore Floating Wind Turbine (OFWT) introduces an additional wind profile to the rotor, which may significantly impact the power performance of the OFWT. In this paper, the power performance of an OFWT in platform pitching motion is investigated using the Free Vortex Method (FVM). Firstly, the pitching and non-pitching cases are compared. Then, the power performance of the OFWT in pitching motions with different amplitudes and frequencies is investigated at the design point (tip speed ratio λ  = 7). Afterwards, the reduced frequency k is proposed to integrate the influences of the platform pitching amplitude and frequency. The power performance curves of the pitching OFWT are derived as functions of λ and k in the whole operating region. Results show that as k increases, the mean power output decreases at low λ but increases at high λ . The mean power coefficient declines with the increase of k . The power variation increases with the increases of λ and k . To make up the loss of the mean power coefficient and to mitigate the side effects resulted from the power variation, advanced control strategies and platforms with good motion performances should be developed for OFWTs. [ABSTRACT FROM AUTHOR]

H 3 PO 4 -doped polybenzimidazole (PBI) membranes have been employed for high temperature polymer electrolyte membrane fuel cell (HT-PEMFC). Although a thinner PBI membrane is beneficial in enhancing power performance, the use of thin PBI membrane has been hindered by its poor mechanical property and consequent difficulty in membrane handling during membrane electrode assembly (MEA) fabrication. Here, novel fabrication route to realize a thin PBI membrane (∼35 μm)-based HT-MEA is presented. The key feature of the process is to fabricate thin blend membrane of PBI and poly(ethylene glycol) (PEG) and laminate the blend membrane to anode gas diffusion electrode (GDE) followed by H 3 PO 4 doping. The introduction of PEG to PBI film enables the tight bonding of the membrane to the GDE at a mild lamination temperature and mitigates the membrane expansion with the doping, preserving the tight interfacial bonding. Due to the lowered membrane thickness, the corresponding MEA exhibits a high power density of 264 mW cm -2  at 0.6 V. Therefore, the new fabrication strategy based on the blend of PBI/PEG is highly effective in improving both process and power performance of HT-MEA. [ABSTRACT FROM AUTHOR]

Large scale wind turbines deployed in “behind the meter” applications at medium and large scale industrial consumer sites can offset the purchase of retail electricity from the utility. However, unlike traditional onshore wind farm sites in elevated rural areas, such industrial sites tend to be at lower elevations and located in more urbanised areas with a higher likelihood of being in vicinity of manmade obstacles such as buildings. This research case study presents observed impacts of various site obstacle features, from local buildings to regional topography on the energy performance of an 850 kW rated wind turbine operating in a peri-urban area. The study is based on the analysis of 10-minute SCADA data measured over multiple years. The analysis includes a novel wind turbine electrical energy rose (EER) approach to determine the directional variation of the wind turbine electrical energy output in relation to site features around the turbine location. The paper concludes that low broad buildings with heights of only 20% of the turbine hub height can have a significant energy reducing impact compared to taller narrow buildings and that hills ~ 8 km from the turbine site have an energy reducing impact. The outcomes of the study should be of benefit to those involved in the pre-feasibility stages of deploying single large scale wind turbines at industrial sites in peri-urban areas. [ABSTRACT FROM AUTHOR]

Electrode engineering is currently of great significance for addressing the challenge of relatively poor power density faced by microbial fuel cell. This work reported that readily available onion-derived activated carbon (AOC) featured with rich content of nitrogen and phosphorous, opened mesoporous structure, revealed as excellent trifunctional electrode modifier for MFC by boosting the anodic charge transfer efficiency and catalyzing cathodic oxygen reduction, which gave rise to nearly 60% increment in the maximum power density (up to 742 ± 17 mW m −2 ), and thirdly rendering the device with distinct transient charge storage capacity that is 15 times of the plain counterpart. It's further revealed that these remarkably enhanced performances could be attributable to the improved electrochemical properties, and intrinsic capacitance of anode by AOC, in addition to its comparable electrocatalytic activity but obviously superior stability over Pt/C toward cathodic ORR. It is anticipated that this sustainable electrode modifier facilely obtained from natural plants with triple functionalities, metal-free nature yet low cost hold great potential for real use of MFC. [ABSTRACT FROM AUTHOR]

This paper investigates the power performance and wake characteristics of a straight-bladed Vertical Axis Wind Turbine (VAWT) with field experiments. In order to observe the aerodynamic forces characteristics, the power performances measured by a torque meter are compared between wind tunnel and field experiments. The values of reference wind and wake velocities are measured through three cup-type anemometers and ultrasonic anemometers. As a result, it is clarified that field experiment result of power coefficient shows higher value than that of wind tunnel experiment at low tip speed ratio in the case of high turbulence intensity. Furthermore, the turbulence intensity has an inhibitory effect on power performance at optimal and high tip speed ratios. The maximum velocity deficit is in the position of −0.2 < y/D < 0. Meanwhile, the recovery process in the velocity deficit region is asymmetric. The predictions of wake velocity distributions in different inflow velocities are also investigated with Gaussian function model. It is estimated that wake velocities recover near the positions of x/D = 3.3 and 4.5 in the cases of U ref = 5.0 and 9.0 m/s. The results have a guiding significance for comprehending the development process of straight-bladed VAWTs. [ABSTRACT FROM AUTHOR]

Nowadays the proton exchange membrane fuel cells (PEMFCs) have gained more importance due to their eco-friendly features. They have been studied extensively due to their positive approach towards the environment, through electrochemical process of power generation. But they still face the issues of non-uniformity of fuel flow, especially in the common type of serpentine flow slab during high current density production. This leads to incomplete reaction of the fuel in the catalyst layer of MFC and will bring about a decrease in its performance. In this study, a modified design of convergent-type serpentine flow slab was designed for a better performance of PEMFCs, based on a series of optimization studies. Results showed that the power performance of PEMFCs in case of convergent-type serpentine flow slab was better than that of serpentine flow slab with a constant duct channel, mainly because improper fuel mixing was prohibited. This convergent-type of serpentine flow slab can effectively postpone the appearance of concentration polarization in PEMFCs. The findings of this study will definitely be useful for the improvement of MFCs performance and their applications in the future. [ABSTRACT FROM AUTHOR]

Aiming at the intake valve timing having a great effect on the volumetric efficiency of the engine, simulation model of 486 gasoline engine was built up by using AVL-BOSST software. The simulation model of the intake performance of the gasoline engine was established and verified. The influence of the parameters such as speed and variable timing on the engine performance was studied. The results show that the different intake valve opening time mainlyinfluents the effect of the gas fluctuation:delaying the intake valve opening time can make full use of the intake inertia supercharging effect toincrease the torque at high speed;the intake valve should be opened in advance to ensure the maximum effective compression ratio at low speed, when the resonant intake effect disappeared. The variable intake timing mechanism is installed on the engine to optimize the intake timing at each speed, which has a great effect on the improvement of the dynamic performance of the low speed and part of the high speed zone. [ABSTRACT FROM AUTHOR]

The oscillating wave surge converter (OWSC) type devices (e.g., an Oyster wave energy converter) generate electric power via rotating motion about the bottom of the device. This type of wave energy converters have a wide power absorption bandwidth which enables the electricity generation at a wide range of wave frequencies. The power produced by the OWSCs could be maximised by configuring individual devices within an array. This paper examines the power production performance of multiple OWSCs in an array under regular, uni-directional irregular wave and multi-directional sea using the industry standard hydrodynamic software WAMIT. The performance of the OWSC array is represented as q -factor, which is a quantity defined as the ratio of the average total power produced in an array to the power produced by an individual OWSC. The results show that the OWSCs arranged in an array would produce both constructive and destructive interferences depending on the wave directions and frequencies. Further, the spreading function, the resonance bandwidth and the optimal spacing between the devices are shown to affect the performance of the OWSC significantly. The results provide an enhanced understanding of the behaviour and performance of the OWSCs when arranged in an array of different configurations. [ABSTRACT FROM AUTHOR]

The installation of a wave farm involves the appropriate selection of a location and a wave energy converter (WEC) for harnessing the energy resource. There is typically a considerable number of options both regarding the site and the technology, and choosing the optimum WEC-site combination is not straightforward. An integrated approach is demonstrated in this work by means of a case study in Burela (Galicia, NW Spain)—an area that has been proposed for wave energy exploitation. First, three possible locations are defined with a view to avoiding potential environmental impacts and the interference of the wave farm with existing uses of the marine space. Then, the power performance of six technologies at the selected locations is computed by means of a comprehensive methodology based on high-resolution numerical modelling, which guarantees accurate and reliable results. Significant spatial variability of the resource over short length scales is found, which translates into large variations in the performance of the various WECs considered. On this basis, the most appropriate site and WEC for the area are determined, thereby the integrated approach for installing a wave farm—which may be used in any other region of interest—is demonstrated. [ABSTRACT FROM AUTHOR]

Corn-straw biochar (BC500 and BC900) and KOH modified biochar (BAC) were used as the electrode materials of bioelectrochemical system (BES). Compared to carbon felt (CF) electrodes BES, the maximum power density of BC500, BC900 and BAC anodes BES increased by 10.7%, 56.0% and 92.0%, and that of BC500, BC900 and BAC cathodes BES increased by 3.1, 5.2 and 4.8 times, respectively. The CF electrodes BES was optimized to decolor the AO7 simulated wastewater and 97% of AO7 was quickly degraded within 2 h. When using biochar anodes, the decoloration rates were enhanced. The apparent rate constant ( k app ) increased from 2.93 h −1 for CF anode BES to 3.58, 4.35 and 5.33 h −1 for BC500, BC900 and BAC anode system, respectively. AO7 could also be effectively decolored in biochar cathode systems, which was mainly due to adsorption. [ABSTRACT FROM AUTHOR]

Microbial fuel cells (MFCs) are a promising technology for simultaneous electricity generation and wastewater treatment. Noble materials can offer high catalyst performance in MFCs but their high cost poses an obstacle for the practical implementation of this technology. Ferroelectric materials such as LiTaO3 are a new generation of photocatalysts that could potentially be used for the oxygen reduction reaction in these devices. Thus, this work investigates the performance of LiTaO3 as cathode catalyst in MFCs for the first time. The power performance of carbon cloth cathodes coated with LiTaO3 was assessed in the presence and absence of light irradiation in MFC systems using wastewater. Prior to be tested in MFCs, the synthesized phase of LiTaO3 was mainly characterized by XRD, particle-size distribution, TEM, and UV-vis spectroscopy analyses. The results show that the performance of the cathode coated with LiTaO3 significantly improves under UV-vis irradiation, with a threefold increase in maximum power density compared with the results obtained in the absence of light source. Under these conditions, COD removal from wastewater reached 66% after 120 h. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1568-1574, 2017 [ABSTRACT FROM AUTHOR]

This paper adopts virtual tank experimental technology to study ship rapidity performance. Based on RANS method, a new method is put forward to predict the speed and power performance of full scale ship. The open water performance of propeller model, the resistance performance of ship model and the self-propulsion performance of ship model are numerically calculated. Through the analysis of rapidity numerical results of fishing ship and the change law of wake flow field, some conclusions can be drawn. The numerical prediction accuracy of propeller open water efficiency has a direct influence on total thrust efficiency. The interference between hull, propeller and rudder leads to the formation of a lower pressure zone on stern hull surface and rudder surface. The axial velocity and radial velocity are affected by the interference between the flow of hull stern and propeller, the absolute value of axial velocity on blade leaf is smaller than that on blade back, and the radial velocity induces vortices on the blade tip of the propeller. The increase of propeller rotation speed nearly has no effect on the free surface wave pattern. The prediction results deviations of full scale ship speed and propeller rotation speed between RANS method and EFD method are 0.04 kn and 0.4 r/min, and therefore they are negligible. The proposed method can provide reference for engineering application. [ABSTRACT FROM AUTHOR]

In this work, exhaustive characterizations of 3D geometries of LiNi1/3Mn1/3Co1/3O2 (NMC), LiFePO4 (LFP), and NMC/LFP blended electrodes are undertaken for rational interpretation of their measured electrical properties and electrochemical performance. X-ray tomography and focused ion beam in combination with scanning electron microscopy tomography are used for a multiscale analysis of electrodes 3D geometries. Their multiscale electrical properties are measured by using broadband dielectric spectroscopy. Finally, discharge rate performance are measured and analyzed by simple, yet efficient methods. It allows us to discriminate between electronic and ionic wirings as the performance limiting factors, depending on the discharge rate. This approach is a unique exhaustive analysis of the experimental relationships between the electrochemical behavior, the transport properties within the electrode, and its 3D geometry. [ABSTRACT FROM AUTHOR]

Solid-state on-chip supercapacitors based on ruthenium oxide coated silicon nanowires were fabricated using a process that is compatible with silicon integrated circuit processing. Ordered arrays of silicon nanowires were fabricated using metal-assisted anodic etching (MAAE). Atomic layer deposition (ALD) was used to form a uniform coating of ruthenium oxide on high-aspect-ratio silicon nanowires at a moderate temperature of 290 °C. Coated nanowire electrodes were studied using cyclic voltammetry and charge-discharge tests in a neutral Na 2 SO 4 electrolyte, and a specific capacitance of 19 mFcm −2 was achieved at 5 mVs −1 . Solid state nanowire capacitors were then fabricated with symmetric face to face nanowire arrays separated by a polymer-based electrolyte. This device exhibited a specific capacitance as high as 6.5 mFcm −2 at 2 mVs −1 . The full device was tested over 10000 cycles under galvanostatic charge-discharge at 0.4 mAcm −2 , and showed a retention of 92% of the specific capacitance. The specific capacitance was found to scale with the total nanowire surface area, as controlled by controlling the aspect ratios of the wires. The solid state nanowire-based device also achieved high specific energies without sacrificing power performance. [ABSTRACT FROM AUTHOR]

In order to identify and compare annual degradation rates of wind turbines, power performance testing was experimentally carried out on the Hankyeong (seaside) and Seongsan (inland) wind farms of Jeju Island, Korea. Five to six years' worth of raw nacelle wind data from SCADA system were analyzed for this work. Power curves were drawn for each year according to IEC 61400-12-1. The AEP and the CF were calculated by applying the drawn power curves to Rayleigh distribution, after which the CF yearly degradation rate was estimated. This constituted the methodology for degradation analysis in this work. The accuracy of this methodology was verified by comparing the relative error between the two CF degradation rates. The second degradation rate was calculated by applying the methodology to the wind data corrected by Nacelle Transfer Function. As a result, CF degradation rates for Hankyeong wind turbines 5 to 9 were found to have a relative error of 5.5% on average. The average CF reduction rates of the Hankyeong and Seongsan wind turbines were revealed to be 0.320%/year and 0.118%/year, respectively. The power performance degradation was found to have been faster for seaside wind turbines than for those located further inland. [ABSTRACT FROM AUTHOR]

To address the issue. that the maximum combustion pressure is too high after a certain V shape diesel engine is modified into two-stage turbocharged system from one-stage turbocharged system, the effects of fuel injection advance angle and compression ratio on the performance and maximum combustion pressure of two-Stage turbocharged diesel engine are simulated by building a simulation model on the software CT-Power and using experimental data, and the united optimization of both the fuel injection advance angle and compression ratio is conducted with the tool DOE of GT-Power by taking experimental maximum combustion pressure of the two-Mage turbocharged engines as limitation und taking the maximum torque as goal. The decrease of the compression ratio can effectively reduces the maximum Combustion pressure at 1300 rpm and 2100 rpm. For every 1 decreased in the compression ratio, the maximum combustion pressure is decreased by 0.8 MPa at 1300 rpm and 1.16 MPa at 2100 rpm, respectively. Relative variations of optimised compression ratio and fuel injection advance angle an- 14.9°CA and 4.3°CA , respectively. The feasibility of the result is validated according to the structural condition of the testing diesel engine. Verification with trial machine is conducted on diesel engine bench. [ABSTRACT FROM AUTHOR]

Wind-wave combined structures have great development potential due to larger power production that they have compared with segregated offshore wind turbines or wave energy converters. The present paper studies a combined structure of a 5-MW braceless semisubmersible floating offshore wind turbine (FOWT) and different configurations of a torus-type wave energy converter (WEC). Various configurations of the combined structure are proposed and investigated based on three-dimensional potential flow theory. Initially, the effects of the number of the WECs that are utilized in different configurations of the combined structure on the hydrodynamic performance of the semisubmersible platform are investigated in the frequency domain by comparing hydrodynamic coefficients. The hydrodynamic coupling mechanisms of the combined structure with different number of WECs are studied. Wave contours are presented and compared to study the interaction effect of surrounding fluid with the combined structure and the examined various configurations. Response amplitude operators (RAOs) and the produced power for the examined combined structures in time domain are compared and discussed, it is indicated that the combined structure with the configuration with use of three WECs has the largest produced power capacity. • The effect of the number of the WECs on the hydrodynamic performance of the semi platform are investigated. • The hydrodynamic coupling mechanisms with different number of WECs are studied. • Wave contours are presented and compared to study the interaction effect. • RAOs and the produced power in the time domain are compared and discussed. [ABSTRACT FROM AUTHOR]

Facing the serious issues of using chemical agents in agro-industry and polluting the soil and water source, the solid microbial fuel cell (SMFC) would be one of solution on managing this problem because of undergoing the compost fermentative process to degrade solid waste effectively and also produce power. Now facing the fact of that water content directly impacts the degrading performance of microorganism during the composting process, a technique of Xanthan 80 Smoother flow(SF) and a drainage design would be utilized in the system undergoing a series of studies for knowing its performance of SMFC. Results show that using Xanthan 80(SF) can enhance the power performance of SMFC significantly because of its excellent ability on keeping the compost moist throughout and preventing the gravitational effect from the accumulation of water at the bottom of the chamber. These findings will be useful to modification of SMFC in the future. [ABSTRACT FROM AUTHOR]

This study presents an experimental investigation of a piston engine driven by compressed air. The compressed air engine was a modified 100 cm3 internal combustion engine obtained from a motorcycle manufacturer. The experiments in this study used a test bench to examine the power performance and pressure/temperature variations of the compressed air engine at pressures ranging from 5 to 9 bar (absolute pressure). The engine was modified from a 4-stroke to a 2-stroke engine using a cam system driven by a crankshaft and the intake and exhaust valves have a small lift due to this modification. The highest power output of 0.95 kW was obtained at 9 bar and 1320 rpm. The highest torque of 9.99 N·m occurred at the same pressure, but at 465 rpm. The pressure-volume (P-V) diagram shows that cylinder pressure gradually increases after the intake valve opens because of the limited lift movement of the intake valve. Similar situations occurred during the exhaust process, restricting the power output of the compressed air engine. The pressure and temperature variation of the air at engine inlet and outlet were recorded during the experiment. The outlet pressure increased from 1.5 bar at 500 rpm to 2.25 bar at 2000 rpm, showing the potential of recycling the compressed air energy by attaching additional cylinders (split-cycle engine). A temperature decrease (from room temperature to 17 °C) inside the cylinder was observed. It should be noted that pressures higher than that currently employed can result in lower temperatures and this can cause poor lubrication and sealing issues. The current design of a compressed air engine, which uses a conventional cam mechanism for intake and exhaust, has limited lift movement during operation, and has a restricted flow rate and power output. Fast valve actuation and a large lift are essential for improving the performance of the current compressed air engine. This study presents a power output examination with the pressure and temperature measurements of a piston-type compressed air engine to be installed in compact vehicles as the main or auxiliary power system.