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Polypropylene (PP)‐based dielectric film capacitors cannot meet the rapid development requirements of electromagnetic energy equipment because of their low energy storage density (Ue). The development of new dielectric materials is hampered by the trade‐off between high energy storage properties and thin film processibility for capacitors. This study proposes a strategy to improve the comprehensive energy storage properties of PP films by reconciling the trade‐offs not only between their polarity and crystallinity but also between their energy storage and processing performance. In this approach, a trifluoroethyl methacrylate (TFEMA) modified PP film is fabricated at the kilogram scale. The TFEMA units regulate PP crystallization in the α‐phase, resulting in improved mechanical, dielectric, and energy storage performance. The optimal PP‐g‐TFEMA film exhibits a remarkable breakdown strength (Eb) of 865 MV m−1 and a record Ue of 8.2 J cm−3 at over 90% discharge efficiency. The promising thin film processibility, excellent self‐healing, and long‐term reliability of PP are finely preserved in the aluminum (Al) coated PP‐g‐TFEMA film. These findings present a novel avenue to significantly increase the Ue of film capacitors for long‐term service not only in academia but also in industry. [ABSTRACT FROM AUTHOR]

Introduction: The hospitalization process has three main stages: an admission, an inpatient period and a final stage with the discharge process. An inefficient bed management in any of the three stages of the hospitalization can cause a mismatch between demand and capacity. It has been proved that when bed demand exceeds capacity, patient admissions and scheduled surgical procedures can be delayed or cancelled. Moreover, the discharge process should start at the point of admission in the case of planned admissions, as in some cases the estimated length of stay without a medical complication is known. Methodology: It is a prospective interventional study was carried out in Nizam's Institute of Medical Science, a tertiary care teaching hospital located in Hyderabad, Telangana, India. Various elements of discharge process are studied using data collection forms which were developed suing Time Motion Study, enclosed in annexure 1 and 2 designed as per events in discharge process. Discharge time is calculated for study sample and steps contributing to delays are noted. Based on the steps contributing to delay, possible interventions are planned and implemented to reduce the delays at necessary steps of discharge flow. The difference of time taken in discharge process before and after intervening is analyzed. The intervention steps contributing to maximum benefit to reduce the total discharge time will be suggested for implementation by the institute. Results: The junior residents are usually entrusted with the task of writing the discharge summaries. The junior resident initiates the task of writing the discharge summary after the end of the morning rounds. Some of the discharge summaries are hand written and some are typed. The hand written summaries are sent to the personal secretary or assistant of the department concerned either by the junior resident or the class IV employee of the ward. Immediate availability of the class IV employee was observed as an issue since he/she would be multitasking in the ward functions. Conclusions: The present study has been conducted in Nizams Institute of Medical Sciences, a super speciality teaching hospital with the aim of studying the current discharge practice, total time taken for the process and implementing few possible interventions to reduce the discharge process time. [ABSTRACT FROM AUTHOR]

Establishing a harmonious equilibrium between high energy storage, minimal energy loss, and exceptional processability presents a formidable challenge within the realm of dielectric polymers. To address this challenge, harnessing the characteristics of long‐chain side groups to enhance polarity and toughness, as well as the fluorine effect to improve insulation and efficiency, a random copolymer, poly(4‐fluorostyrene‐trifluoroethyl methacrylate) (P(FS‐3FEMA)), is successfully synthesized via copolymerization of fluorine‐containing monomers, namely 4‐fluorostyrene (FSt) and trifluoroethyl methacrylate (3FEMA). Experimental findings demonstrate that elongating side chains enhances polymer toughness, boosts polarization strength, and self‐healing capacity. Introducing fluorine atoms into side chains maintains toughness while marginally increasing polymer chain spacing, reducing relaxation loss induced by dipole reorientation under an applied electric field. Additionally, fluorine incorporation enhances electron capture, effectively reducing leakage loss and the likelihood of thermal and electrical breakdown. Ultimately, the copolymer exhibits exceptional performance, characterized by extraordinarily high energy storage (Ue = 18.3 J cm−3), minimal energy loss (efficiency exceeding 89%), and enhanced toughness (increased by over 112%). This study presents a novel approach that harnesses the fluorine effect to reconcile the conflicting requirements of high energy storage, minimal energy loss, and exceptional processability in polymer dielectrics. [ABSTRACT FROM AUTHOR]

In order to define the hydraulic operating parameters of the RC FARM model sprinkler for use in the design of sprinkler irrigation systems, a field evaluation was developed in areas of the Agricultural Engineering Research Institute located in Havana, Cuba. In the evaluation, two sets of nozzles were tested and the procedure that appears in the Cuban Standard NC ISO 8026:2014 was followed. To characterize the performance of the sprinkler, the following indicators were used: Uniformity Coefficient (CU), Statistical Uniformity of Uniformity (CEU), Uniformity of Distribution (UD) and Discharge Efficiency (Ed). The losses produced by evaporation and carryover during the test were evaluated as part of the work. The results show that the sprinkler model RC FARM with nozzle 4, 70 mm + 3, 18 mm is characterized by having a flow of 1697,0 L h-1 and an effective reach radius of 11,28 m while with the nozzle 3,97 mm + 3,18 mm the flow is 1476,0 L h-1 and effective radius of 10,15 m, in both cases for a pressure of 250 kPa. The quality of the water distribution for the evaluated sprinkler is defined as acceptable as having CU values greater than 70%, CEU above 65% and UD and Ed indicators that exceed 55 and 63%, respectively. Evaporation and carryover losses during the test reached values of 11,54% and 10,61%. [ABSTRACT FROM AUTHOR]

The discharging homogeneity and discharge efficiency of fresh concrete are the most important aspects of engineering practices of researchers. In this study, the influence of the main structural parameters of the blade on the discharge homogeneity and efficiency is numerically simulated through an orthogonal test based on the discrete element method. The order of influence of the blade structural parameters on the discharging homogeneity was obtained through range analysis and determined: t-shaped blade width > blade width > blade pitch > blade swing angle. Regarding the discharge efficiency, the influence order is blade pitch > blade swing angle > t-shaped blade width > blade width. Considering the discharging homogeneity and discharge efficiency, the optimal width of the t-shaped blade, blade pitch, blade width, and blade swing angle of the front cone–central cylinder–back cone were established as 120 mm, 1800–2280–1680(mm), 480–440–390 (mm), and 90°–90°–75°, respectively. [ABSTRACT FROM AUTHOR]

The thermal behavior in aluminum-air battery has prominent effect on its operation performance, however, the investigations to the battery thermal behavior are still scarce. In this paper, an alkaline vehicular traction aluminum-air battery was designed and its thermal behavior was experimentally investigated. The impacts of various parameters were examined, including the ambient temperature, electrolyte concentration, and discharge current density on the battery's temperature-rise, outgoing heat-flux, heat generation rate, and discharge efficiency, etc. It is shown that the battery's temperature-rise, outgoing heat-flux, and heat generation rate increase with the ambient temperature decreases and the electrolyte concentration increases. Furthermore, the battery heat generation rate decreases over the discharge time, particularly it decreases drastically at the first half of discharge. The discharge efficiency of the battery increases with the increases of operating temperature and discharge current density. The battery discharge efficiency varies with the electrolyte concentration, which approaches 78 % under the electrolyte concentration of 3.0 mol L−1, but less than 60 % under the concentrations of 1.0 mol L−1 and 6.0 mol L−1. The present study compensates a vacancy of the thermal behavior characterization for a vehicular traction aluminum-air battery, and the results are of significance in understanding the aluminum-air battery's thermal behavior. • An alkaline Al-air battery is devised. • Proposes a measurement method to characterize the Al-air battery thermal behavior. • Impacts of thermal behavior on Al-air battery operating performance is studied. [ABSTRACT FROM AUTHOR]

Copyright of Misr Journal of Agricultural Engineering is the property of Egyptian National Agricultural Library (ENAL) 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.)

Downstream submergence can determine the relationship between the water head and the discharge capacity of the weir, once the tail water exceeds the weir crest elevation in the channel application of weirs. This study aims to explore the discharge characteristics of Piano Key Weirs (PKW) under submerged flow conditions. A series of physical tests were carried out for the four types of PKW in a rectangular flume. The relationship between the total head on the upstream/downstream and the submergence coefficient of PKW flow was obtained in the variation process with the downstream water level under the submerged flow. The flow reduction coefficient and dimensionless water head method were also used to determine the relationship between the total head and flow reduction coefficient of PKW and the submergence coefficient. An analysis was made on the sensitivity of four PKW types to submergence. The fitting was performed on the formula of submergence flow reduction coefficient of PKW. The reverse standardized upstream water head method was utilized to compare the hydraulic efficiency of four PKWs under submerged conditions. The experimental results show that the impinging jet, breaking (surface jumping), surface wave, and surface jet flow after the four kinds of PKWs appeared in sequence, as the downstream water level rose. Specifically, the type C and D PKWs were gradually submerged at the submergence coefficient S=0.6, when the upstream discharge was constant. The discharge reduction coefficient decreased with the increase of the submergence coefficient. The type B and A PKWs entered the submergence state in advance, when S≥0.15 and S≥0.2, respectively. Correspondingly, the critical submergence Sm of four types of PKWs were: type A 0.5, type B 0.3, type C 0.7, and type D 0.65, respectively. In contrast, the type B PKW with only upstream overhang structure was the most sensitive to the submergence, followed by type A with the symmetrical upstream and downstream overhang structure, while the overhang structure towards the downstream was delayed the upstream submergence. Different PKWs varied differently under the downstream water level, which was mainly related to the overhang length of the upstream and downstream of each model. The longer the overhang in the upstream was, the slower the slope of the outlet key was, and the more likely it was to be submerged. In the type C and D PKWs with the longest downstream overhangs, the water nappes flowing through the inlet key under the action of the inertia of the water flow, pushed the downstream water flow to a position far away from the PKW crest, thus delaying the effect of submergence. Finally, the calculation formula of submerged discharge coefficient was fit to further compare the discharge capacity and hydraulic efficiency of four types of PKWs under submerged conditions. It was found that the discharge efficiency of type C and D PKW was lower than that of type A PKW, and the efficiency of type B was the highest when the submerged coefficient S was relatively small. There was a reverse variation in the discharge efficiency of each type of PKW, when S≥0.7. The submerged discharge efficiency of four types of PKW depended on the comprehensive influence of “sensitivity to submergence” and free-flow discharge efficiency. The findings can provide technical support for the optimal weir flow of the PKW in the application of open channels and rivers [ABSTRACT FROM AUTHOR]

An initial step is made towards improving the global water application uniformity of centre pivots by adjusting the lateral speed based on diurnal changes of wind drift and evaporation losses (WDEL). A large WDEL dataset was used to construct an artificial neural network (ANN) model capable of predicting the above ground application efficiency (AGAE ≈ 1- WDEL) from input weather data. Given its reasonably good accuracy (RMSE = 1.5%), the ANN model was then applied in heuristic, simple and dynamic algorithms that used forecasted or real-time weather parameters corresponding to the hourly time intervals of the pivot's revolution time. For each timing interval, the final output of the algorithms is a coefficient (λ), that when multiplied by the lateral speed, can ensure a more consistent water delivery depth across the field. The proposed algorithms were theoretically tested for extremely hot, dry, humid, and windy days. These efforts indicated that under the climatic conditions of the study, λ could potentially vary between 0.92% and 1.06% if the revolution time is about 24 h. The λ coefficient typically increased from 1:00 AM to 9:00 AM, then decreased until the sunset, between 19:00 to 21:00, and then increased again until midnight. This general trend for λ could however, be disrupted by sudden changes in the wind speed. Future studies should conduct extensive field work to test the efficacy of the proposed algorithms and quantify the improvement of centre pivot global water application uniformity through the lateral speed adjustment. • Centre pivot lateral speed can be adjusted to account for a changing application efficiency. • Two theoretical algorithms were developed to improve the global water application uniformity. • The first algorithm uses forecasted weather data while the second uses real time data. • The lateral speed adjustment factor varied within ±6% during a 24-hr cycle. • Centre pivot lateral speed adjustment is easy to implement. [ABSTRACT FROM AUTHOR]

To further explore the machining characteristics of very high-frequency micro-electrical discharge machining (VHF micro-EDM), the range of radio frequency (RF) power amplifier was expanded to 110 MHz, and the power of the RF power amplifier was also greatly increased up to 91 W. The principle of the VHF pulse generator was discussed in detail, and an electro-thermal model suitable for VHF micro-EDM was established to determine the diameter of the plasma channel and the energy distribution ratio. Experimental studies for VHF micro-EDM were also carried out, and the effects of power and frequency on machining characteristics were then analyzed and discussed. The results show that at the same frequency, the higher the power is, the higher the material removal rate (MRR) and the larger the number of discharge craters. At the same power, both the MRR and the size of discharge craters first increase and then decrease with increasing frequency and peak at 65 MHz. For a copper workpiece, when the frequency is 110 MHz and the total power of the power amplifier is 8.0 W, 5.6% of the energy is used for the material removal of the workpiece and the finest processing surface is obtained with the surface roughness Ra = 12 nm. The average diameter of the discharge craters is as small as 0.268 μm, and the diameter of the plasma channel is only 0.350 μm. In addition, the effects of different workpiece materials and dielectric fluids are also analyzed in this paper. [ABSTRACT FROM AUTHOR]

Since their development, as a result of an improvement of labyrinth weirs, Piano Key Weirs (PKWs) have been implemented as (a) a flood safety structure for gravity dams, allowing to also increase their storage volume, and (b) in river systems to increase the water level for hydropower or navigation purposes. The rectangular folded crest, consistent with apexes inclined by turns in the upstream and in the downstream direction, turns the PKW a device with a high discharge capacity, especially useful during wet extreme events. Nevertheless, several modifications have been implemented in the PKW geometry, capable to improve and, in some cases, worsen their efficiency. Herein, an experimental and numerical assessment, using the ANSYS Fluent Computational Fluid Dynamics (CFD) software, of the discharge coefficient is presented for two PKW configurations, evaluating the specific discharge over the upstream, downstream, and lateral crests, the velocity in the inlet and outlet keys, and the water surface profile, as well. The investigated configurations are a symmetric type A, designed following the recommended optimal values, and a type B model, with the same geometric features as type A. Results showed that for the specific geometries, the type B is more efficient for lower head; however, once the filling of the outlet key occurs, the type B efficiency is reduced, leading to type A becoming more efficient.

The objective of the work was to study the technical-operational parameters of the electric central pivot machines and their relationship with the norms of water delivery to crops. For the analysis, seven central pivot machines were selected in three productive entities of Güira de Melena Agricultural Enterprise, which were hydraulically evaluated to know their operating status according to NC ISO 11545. The parameters studied were the uniformity coefficient, distribution uniformity and discharge efficiency as indicators of irrigation quality. The results showed that the wind has a marked influence on the evaluated technical-operational parameters, deteriorating the quality of irrigation to average values of Heermann and Hein Uniformity Coefficient of 79.39%, Distribution Uniformity25% of 64.90% and Discharge Efficiencies of 74.08%, which directly affects the low percentage of area adequately irrigated. When the gross partial norms of the operation tables for efficiencies of 85% were compared with those obtained in the field evaluations, it was possible to know that deficits in deliveries between 6 and 23 m3 ha-1 can occur in each irrigation duty. [ABSTRACT FROM AUTHOR]

A piano key weir (PKW) is a solution for improving the efficiency and safety of reservoirs and simplifying their management. To investigate the influence of the inlet/outlet width ratio W i / W o on the discharge efficiency of PKWs, a three-dimensional numerical model based on a standard k − ε turbulence model and volume-of-fluid (VOF) method is employed, and the flow characteristics of nine laboratory-scale PKWs with different W i / W o ratios are studied numerically. The results confirm that PKW configurations with W i / W o > 1 are generally superior to those with W i / W o < 1 in terms of discharge capacity. However, as the water head rises, the discharge efficiency of the PKW with a greater W i / W o decreases more rapidly. By decomposing the total discharge into inlet, lateral and outlet components, according to the flow features of each overflow crest and their contributions to the total discharge, the intrinsic influencing mechanism of W i / W o on the discharge performance of PKWs is revealed. [ABSTRACT FROM AUTHOR]

The development of lead-free ceramics with high recoverable energy density (W rec) and high energy storage efficiency (η) is of great significance to the current energy situation. In this work, a new scheme was proposed to improve the W rec and η of potassium sodium niobate ((K, Na)NbO 3 , abbreviated as KNN) lead-free ceramics. Doping Bi elements in KNN ceramics to form a second phase (K 2 BiNb 5 O 15) can reduce the grain size and form Schottky-like contact. Meanwhile, the hybridization between the Bi 6p and O 2p orbitals can enhance the maximum polarization (P max). So the K 1-3x Bi x Na 0.5 NbO 3 -1 mol%CuO ceramics was proposed to improve the W rec of lead-free ceramics. A large W rec (2.89 J/cm3) and dielectric breakdown strength (DBS) (300 kV/cm with a thickness of 0.2 mm) were achieved for K 0.14 Bi 0.12 Na 0.5 NbO 3 -1 mol%CuO ceramics. The high W rec was supposed to benefit from low remnant polarization (P r), high Ps and DBS of ceramics. In addition, a large η (80%) was simultaneously achieved for K 1-3x Bi x Na 0.5 NbO 3 -1 mol%CuO ceramics, which is superior to mostly reported lead-free bulk ceramics. The results show that K 1-3x Bi x Na 0.5 NbO 3 -1 mol%CuO ceramics have a good application prospect in the field of energy storage, and provide a new scheme for the preparation of lead-free ceramics with high energy storage density and high conversion efficiency. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials 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.)

Summary: A dynamic research endeavor has been performed in this research study by constructing and operating an innovative flowing type anode (zinc gel) along with Carbopol 960 additives as thickener in a zinc‐air fuel cell. This gel constituted of a mixture of Zn powder, thickener, and potassium hydroxide (KOH) electrolyte, and it was fueled into the cell with a peristaltic pump. The flowing Zn anode allowed the reaction‐produced water, carbonate, and zinc oxide (ZnO) to be discharged from the cell. Basic operating parameters of the fuel cell like the concentrations of the Zn powder, thickener, and electrolyte along with the number and grid density of the current collector grid, cell operation temperature, and air flow rate were all optimized for effective and enhanced fuel cell performance. It was determined based on voltage production along with current and energy density generation. The augmented experimental results were as follows; thickener concentration of 1 to 2 wt% was observed to be optimum above which the electrolyte acquired a solid state. The voltage production was stable at electrolyte concentrations of 60 to 65 wt% and Zn powder concentrations lower than 40 wt%, and concentrations greater than this resulted in reduced cell performance. The implementation of four current collector grids each with an opening density of 144 grid/cm2 had efficiently amplified cell performance. The ideal cell temperature was determined to be 40°C, and maximum cell production was attained at an air flow rate of 2 m/s. Consequently, effective improvement and advancement in the processes and operational parameters were achieved in this zinc‐air fuel cell with a state‐of‐the‐art anode fuel. This will surely provide great opportunities for their applications in the future. [ABSTRACT FROM AUTHOR]

The high discharge energy density and excellent discharge efficiency are important indicators for measuring the performance of the capacitor. This work systematically studies the sandwich structure ceramic/polymer composites in which the original poly(vinylidene fluoride) (PVDF) is used as the outer layer, and the one‐dimensional K0.5Na0.5NbO3 nanofibers and PVDF composites are used as the intermediate layer. The experimental results show that the energy storage performance of the composite films can be effectively improved by rationally designing and optimizing the filler content. The finite element simulation verifies that the sandwich structure composites mainly reduce the electric field strength of the intermediate layer by adding ceramic fibers, which hinder the growth of the electric trees. In addition, reasonable filler content and optimized structural design can significantly reduce the electrical conductivity, thereby achieving excellent discharge efficiency. In the optimized sandwich structure composites, the high energy density of 14.2 J cm−3 and excellent discharge efficiency (η = 78.5%) are achieved when the breakdown strength is 420 MV m−1. This unique sandwich structure design and high aspect ratio achieve high discharge efficiency and energy storage density provide a reference for next‐generation dielectric materials. [ABSTRACT FROM AUTHOR]

Pollutant removal is a critical procedure for wastewater treatment because it directly determines the effectiveness of wastewater treatment and water conservation. Therefore, assessing pollutant discharge efficiency in wastewater treatment is imperative. In this study, an environmental production technology with a non-radial data envelopment analysis model is developed to examine the discharge efficiency and reduction potential of pollutants in wastewater treatment in 68 key cities by considering the disparity of city scales. By comparing discharge efficiency and reduction targets released in the 12th Five-Year Plan, this study identified the key areas that need to be addressed for wastewater treatment with regard to different city types. Results showed that chemical oxygen demand (COD) and ammonia nitrogen (AN) have similar discharge efficiency values, mainly ranging from 0.5 to 0.7. More specifically, the discharge efficiency of COD is comparatively lower than that of AN. City size generated a positive impact on efficiency improvement. Centralized treatment system is beneficial for achieving the scale effect in wastewater treatment. An examination of the progress of reduction target systems indicated that AN is comparatively inferior in reduction completion. Apart from the technical barriers, this fact is highly related to the willingness and power of the local government. Cities should identify the key areas that need to be addressed and adopt the corresponding reduction strategies by referring to their scales. The findings of this study can facilitate the inclusion of pollution mitigation in the urban agenda, thereby fostering an effective wastewater treatment process and creating a benchmarking framework for governing wastewater pollution. • City-level pollutant discharge efficiency of wastewater treatment is measured. • Inter-city efficiency difference and the scale effect are discussed. • Cities' role in achieving national reduction targets in COD and AN is explored. • Cities are divided to four types to take stratified reduction strategies. [ABSTRACT FROM AUTHOR]

The goal of the present work was to define the quality parameters and exploitation in low intensity irrigation system under production conditions in "La Rebeca" farm, contributing in a better management of water for agrarian use. For the field evaluations the methodologies use was UNE 68-072-86 in 1986 and ISO 15886-3 in 2004, were also determined the Uniformity Distribution according to Merriam and Keller in 1978; Uniformity Coefficient of Christiansen of 1942; Discharge efficiency like Tarjuelo in 2005 indicates, the percent of irrigation areas were also calculated. The obtained results show that the wind in the farm has great incidence in the deterioration of the irrigation quality parameters, reducing the effective radio reach of the sprinkler in 0,90 m with respect to the project. In the triangular covering mark the best results in Uniformity Coefficient of Christiansen are obtained with 90,46%; Uniformity Distribution of 84,20% and the best irrigation percent area with 61,22%, confirming the effective of this setting mark for the study area and others with similar characteristic of high wind speeds. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control 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.)

We investigated the effect of circuit parameters on shockwaves generated by electrohydraulic discharge (EHD), and the application of EHD to stimulation of coal seam gas reservoirs. The discharge circuit analyses indicate that the deposited electrical energy used for shockwave generation is not simply determined by charging voltage or capacitance. The discharge efficiency is also affected by mutual interactions among inductance, resistance and capacitance as well as real-time current change. Furthermore, the relation between charging voltage and peak pressure strength revealed that voltage at breakdown point, ranging from 9 kV to 28 kV, was more closely associated to shock strength rather than the initial charge voltage. Generally, a higher breakdown voltage tends to lead to a stronger shockwave. Finally the EHD fracturing stimulation conducted on coal cubes showed the coal was effectively fractured with enormous cracks and voids. By using three-dimension computed-tomography (CT), the fracture extension and propagation in the coals are found to be obvious and extensive. Though the existing fracture greatly affects the new fracture development in vertical direction, the horizontal fractures parallel with the bedding plane direction are more likely to occur and even expand across the entire tested coal core. The dramatic coal permeability improvement (over a hundred times) after EHD also validates the cutting-through fractures, as does the enhancement of pore and porosity observed by morphology and structural characterisation via scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP). • A comprehensive electrohydraulic discharge (EHD) system was developed for shockwave generation and coal fracturing. • The strength of shockwave is more closely associated with breakdown voltage U b than charging voltage U c. • The capacity of EHD to create multi-scale pores/fractures in both the exterior and interior of coal has been validated. • Both pre-existing fractures and coal bedding plane direction have great impacts on new fractures' formation and extension. [ABSTRACT FROM AUTHOR]

Graphical abstract Schematic and energy conversion of PSJ actuator. Highlights • Electrothermal efficiency is estimated by dynamic chamber pressure measurement. • Influences of wire resistance, capacitor, anode-to-cathode gap et al. are studied. • Discharge efficiency is analyzed based on plasma arc resistance characteristic. • Electrothermal efficiency is analyzed based on major energy loss in pressurization. Abstract Gas discharge plasma techniques have been applied successfully in a wide range of fields. As one of these techniques, plasma synthetic jet (PSJ) actuator shows promising application in high-speed flow control. However, for practical application to aircraft, the capacity of the power source is very limited. So the energy efficiency optimization of PSJ actuator is vital to its longtime effective performance. The overall efficiency of PSJ actuator can be divided into three parts: discharge efficiency, electrothermal efficiency and exhaust efficiency. In this paper, discharge and electrothermal efficiencies of a home-designed and manufactured two-electrode PSJ actuator working in single-shot mode and normal atmosphere are evaluated experimentally. The influence of circuit parameters and actuator configurations are investigated and analyzed as a reference for optimization. The results show that, discharge efficiency is basically determined by the resistance ratio of the RLC circuit. The parasitic resistance of the circuit has a great influence on discharge efficiency due to the very short length and low resistance of the plasma arc (O (100 mΩ)). Electrothermal efficiency seems to be less affected by the circuit parameters and actuator configurations compared to discharge efficiency. The variation extent of electrothermal efficiency is around 50–70% for the tested conditions. Smaller discharge chamber volume produces PSJ with higher speed, but will reduce electrothermal efficiency. For a certain overall input energy required, a design of smaller capacitance and wider anode-to-cathode distance is highly recommended to increase both discharge efficiency and electrothermal efficiency. [ABSTRACT FROM AUTHOR]

Polymer dielectrics with high energy density and low dielectric loss are highly desired due to the rapid development of electric devices. Among known polymers, poly(vinylidene fluoride-ter-trifluoroethylene-ter-chlorofluoroethylene) P(VDF-TrFE-CFE) is one of the promising materials for energy storage capacitor applications because of its high dielectric constant. Nevertheless, it suffers from high dielectric loss especially at the high electric field, which suppresses its breakdown strength and energy storage density. Herein, sandwiched structure dielectric films were fabricated by employing polymethyl methacrylate (PMMA) as the outer layer and P(VDF-TrFE-CFE) as the central layer. By modulating the thickness of the central layer, an enhanced discharged energy density of 7.03 J/cm^3 is achieved at a high electric field of 480 MV/m, which is 132% more than that of P(VDF-TrFE-CFE) at its maximum electric field 300 MV/m. Meanwhile, this sandwiched structure film also retains a high discharge efficiency of 78% at 480 MV/m, which is never been seen in polyvinylidene fluoride-based polymers. Results show that PMMA acts as charge barrier and simultaneously enhance the breakdown strength and suppress the dielectric loss of P(VDF-TrFE-CFE).

The [x BaO, (1 − x) SrO]-Na2O (x = 0.0, 0.2, 0.5, 0.8) niobate-based glass-ceramics were prepared through the controlled crystallization method. Crystallization mechanism, phase structure, dielectric properties, and energy-storage properties were studied by adjusting Ba/Sr ratio. It was found that the surface and internal crystallization occurred simultaneously at first crystallization peak, while surface crystallization occurred at second crystallization peak. With Ba/Sr ratio increasing, dielectric constant increased firstly and then decreased, while dielectric loss firstly decreased and then increased. When x = 0.2, optimal dielectric constant of 88 and dielectric loss of 0.0055 were obtained, which is related to the solid solution phase Sr0.5Ba0.5Nb2O6. Breakdown strength (BDS) showed a behavior of increase before decrease. The highest BDS reaches 1975 kV/cm for x = 0.2, which is attributed to uniform and dense microstructure. Correspondingly, the theoretical energy-storage density was increased up to 15.4 J/cm3. Also, discharged efficiency reaches a high value of 91%. Discharged power density of 0.65 MV/cm3 was obtained for x = 0.2 in the RLC pulsed circuit. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • 2 vertical slot (VSF) and 3 multi slot (MSF) fishways were assessed with 3D CFD. • MSF needs a lower discharge to operate than VSF, while keeping similar flow depths. • Velocity, turbulent kinetic energy, and Reynolds shear stress in the MSF are much lower. • MSF could be less selective and a better option for a multiple-species fishway. Abstract Adequately designed fishways mitigate the negative effects of barriers in rivers, restoring longitudinal connectivity. To do so, they must present suitable hydraulic conditions, with velocity and turbulence fields adequate for multiple fish species. In the present study, numerical modelling was used to compare the hydrodynamics of two widely used vertical slot fishways (VSF) configurations and three multi slot fishway (MSF) configurations. The MSF configuration needs a lower discharge to operate than the VSF, while keeping similar flow depths, which is vital in regions where water availability is limited, such as most Mediterranean regions. By reducing the discharge, the velocity, turbulent kinetic energy, and Reynolds shear stress values in the studied MSF configurations are much lower than the values for VSF configurations. Thus, besides requiring smaller discharges than similar VSF geometries, the MSF additionally could be less selective for fish species, particularly smaller-sized individuals, and individuals with weaker swimming capacities, and a better option for a multiple-species fishway. [ABSTRACT FROM AUTHOR]

A comprehensive numerical investigation was performed to better understand the flow patterns of Piano Key weirs (PKW) for different upstream heads, based on the volume-of-fluid model. The results of numerical simulation indicate that, the efficiency of side crests are limited by following factors: the change of side crest flow direction caused by the effect of the longitudinal flow velocity along the inlet keys, submerged flow regime in outlet keys, interference between nappes, and the head loss along the inlet keys, under the conditions of high upstream head, which eventually leads to the decrease in discharge efficiency with an increase in the upstream head. An orthogonal analysis revealed that, the weir height, inlet/outlet key width ratio, significantly affect the piano key weir discharge efficiency. New formulas with obvious physical significance and high accuracy for the piano key weir discharge were then derived and verified, which improve the accuracy of the design and structural optimization of the piano key weir. [ABSTRACT FROM AUTHOR]

Purpose. Development of similarity criteria for different modes of operation of the solid-state heat accumulator working due to accumulation of heat in the volume of the heat storage material without phase transition, and the creation of systematic criteria of heat accumulator efficiency for determination the weight / size parameters and operating modes at the design stage. Methodology. To achieve the objectives of the study the theory of similarity and dimensional analysis were used as well as planning and carrying out techniques of physical experiments. Findings. Based on the theory of similarity and dimensional analysis similarity criteria operation of solid-state heat accumulators, under given basic parameters were obtained. These are performance criteria for charge, discharge and full criterion. Three theorems of similarity theory in application to the solution of engineering problems were used. The criterion of efficiency of the heat accumulator charge characterizes the effectiveness of achieving the specified value of the specific amount of heat in the material of heat accumulator under charge, under received materials, geometrical ratios, and heat flow of the heat input. The efficiency criterion characterizes the discharge efficiency of the heat accumulator, at the accepted materials; mass of heat-retainer and the total accumulated amount of heat when the value of the heat flow and the time of discharge. Full coefficient of the heat accumulator performance characterizes the efficiency of the heat accumulators for a full cycle. Originality. Accordingly to the analysis the implementation of any system of solid-state heat accumulator is possible on the basis of structural schemes of this type of device. The similarity criteria of the efficiency of the charge, the efficiency of discharge and the full criterion of solid-state heat accumulators’ efficiency based on the solid storage material without phase transition were obtained. Practical value. Criteria presented in this work are of a comparative nature. In accordance with the obtained criteria we can compare designed and existing heat accumulators that are similar to structures. Feasibility analysis indicates that the proposed assessment methodology of solidstate heat accumulators’ efficiency in different modes of operation is effective, technically feasible and allows determining the weight / size parameters and modes of operation of the solid-state heat accumulator at the design stage.

In this work, [ x SrO, (1 − x )BaO]-K 2 O -Nb 2 O 5 -SiO 2 (SBKNS, x = 0.2, 0.4, 0.6, 0.8) glass-ceramics were synthesized through the controlled crystallization method. The phase structure, dielectric and energy-storage properties were systematically studied through the Sr substitution for Ba. It was found that the dielectric properties were improved due to the formation of solid liquid phase Sr 0.5 Ba 0.5 Nb 2 O 6 . Breakdown strength firstly increases and then decreases, which strongly depends on the variation in interfacial polarization. The highest value of breakdown strength reaches 1828 ± 88 kV/cm for x = 0.4, which is attributed to more uniform and dense microstructure and lower interfacial polarization. Correspondingly, the optimized theoretical energy-storage density reaches up to 17.45 ± 0.74 J/cm 3 . The maximum of discharged energy-storage density of 1.45 J/cm 3 from P-E loop was acquired under electric field of 500 kV/cm. Moreover, discharged power density of the capacitor was evaluated and reached a high value of 1.76 MV/cm 3 in pulsed charged-discharged circuit. [ABSTRACT FROM AUTHOR]

The SrO-Na 2 O-Nb 2 O 5 -SiO 2 (SNNS) glass-ceramics were prepared through the melt-quenching combined with the controlled crystallization technique. XRD results showed Sr 6 Nb 10 O 30 , SrNb 2 O 6 , NaSr 2 Nb 5 O 15 with tungsten bronze structure and NaNbO 3 with the perovskite structure. With the decrease of crystallization temperature, dielectric constant firstly increased and then decreased, while breakdown strength (BDS) was increased. High BDS of the glass-ceramics is attributed to the dense and uniform microstructure at low crystallization temperature. The optimal dielectric constant of 140±7 at 900 °C and BDS of 2182±129 kV/cm at 750 °C were obtained in SNNS glass-ceramics. The theoretical energy-storage density was significantly improved up to the highest value of 15.2±1.0 J/cm 3 at 800 °C, which is about 5 times than that at 950 °C. The discharged efficiency increased from 65.8% at 950 °C to 93.6% at 750 °C under the electric field of 500 kV/cm by decreasing crystallization temperature. [ABSTRACT FROM AUTHOR]

Adequately designed vertical slot fishways (VSF) mitigate the impact of anthropogenic obstructions on fish migrations. Until now, most studies on VSF were conducted focusing on high priority species, particularly salmonids, while other species, such as cyprinids, have received less attention. In Mediterranean rivers, where water availability is a problem, effective low discharge fishways are desirable. Attempting to contribute towards filling this gap, the present study focuses on the behaviour and passage performance of two Iberian cyprinids with different ecological traits, the Iberian barbel ( Luciobarbus bocagei , Steindachner, 1864) and the Southern Iberian chub ( Squalius pyrenaicus , Günther, 1868). Fish passage performance was investigated in a full-scale experimental VSF under two different slot configurations (C1 and C2), which require different discharges for equal mean water depths in the pools (Q = 110 L s −1 , for C1, and Q = 81 L s −1 , for C2). Results show that the chub, a small-bodied fish that utilises the upper portion of the water column, performed a higher number of upstream movements in C2, while for the barbel, a large-bodied potamodromous bottom-oriented fish, the performance was similar in both configurations. With similar overall passage success, slot configuration C2 requires a lower discharge to operate, making it the more cost-effective geometry, especially in regions affected by water scarcity. [ABSTRACT FROM AUTHOR]

We have investigated a series of compositions in the pseudo-ternary lead-free alloy system Na 1/2 Bi 1/2 TiO 3 -BaTiO 3 -BiFeO 3 with regard to its energy storage density and discharge efficiency. A composition 0.4(Na 0.5 Bi 0.5 TiO 3 )-0.225BaTiO 3 -0.375BiFeO 3 of this series was identified to give the best energy density and discharge efficiency. While conventional sintering gave energy density of 0.77 J/cm 3 and discharge efficiency of 67%, we achieved a remarkable increase in energy storage density (∼1.4 J/cm 3 ) and discharge efficiency (∼90%) by using spark plasma sintering of this composition. Our results suggest that this alloy system can be a potential lead-free candidate for high electric energy storage and discharge efficiency. [ABSTRACT FROM AUTHOR]

The traditional catch-can technique for measuring water depth application under sprinkler irrigation systems has the limitation of being unable to monitor the continuous variation of wind drift and evaporation losses (WDEL) under changing weather conditions. Such information is essential to better manage the agricultural water by improving the global water application uniformity under moving irrigation machines. Three parallel, long, impermeable water collection strips were constructed underneath a stationary linear move irrigation system to address this issue. The sprinkler discharge efficiency (SDE ≈ 1- WDEL) was monitored over 5-min intervals (SDE 5min ) during Apr-Aug of 2014-on a bare experimental plot. Experiments were conducted on a discrete basis for about 1040 h total in order to collect more than 11,600 SDE 5min data points. It was found that the SDE 5min is very dynamic and can experience abrupt changes up to 16.5% as a result of sudden changes in wind speed and direction. The maximum and minimum observed SDE 5min during the study period were 97.5 and 73.6%, respectively. The difference between maximum and minimum SDE 5min during a day/night cycle was controlled by solar radiation and maximum wind speed. The average hourly SDE (SDE hr ) for data collected at predawn, morning, afternoon, and evening were 89.5, 87.7, 86.9 and 88.8%, respectively. Overall, the daily SDE was mainly controlled by air temperature and varied between 81.8 and 91.8%, indicating that ∼8–18% of the daily applied water was lost on average. A multiple linear regression model was developed to help predict the SDE hr as a function of weather parameters. The model indicated wind speed, temperature and relative humidity as the best explanatory variables and predicted the SDE hr with an absolute error just over 4%. Because the difference between maximum and minimum SDE hr over a full experimental day could be as high as 22%, this magnitude of error was considered to be acceptable for wind drift and evaporation loss estimation. [ABSTRACT FROM AUTHOR]

The niobate-based glass-ceramics with a high energy storage density were prepared by using the controlled crystallization technology in the (Na 2 O, SrO) Nb 2 O 5 SiO 2 glass-ceramics. The dielectric properties, energy storage density, and discharge properties were investigated with the variation of the Na/Sr molar ratio. By varying the Na/Sr ratio, the energy storage density raises up to a high value of 10.09 J/cm 3 . With the variation of the Na/Sr ratio, both dielectric breakdown strength and discharge efficiency have an opposite change trend with the activation energy that reflects the interface polarization of the glass-ceramics. In contrast, for Na/Sr = 1/2, the glass-ceramic has the lower activation energy, which indicates that its interfacial polarization is weaker due to a fine microstructure. Thus, the glass-ceramics for Na/Sr = 1/2 have the characteristics of the higher breakdown strength of 2074 kV/cm and the higher discharge efficiency of 90.1%. Then it may contribute to the high energy storage density capacitor. [ABSTRACT FROM AUTHOR]

The barium potassium niobate-based glass-ceramics with high energy-storage density, high discharge efficiency, and fast discharge speed have been prepared. It was found that dielectric breakdown strength decreases when the crystallization temperature increases. Glass-ceramics have high energy-storage density up to 14.58 ± 1.14 J/cm3 with high breakdown strength of 2382 ± 92 kV/cm. Discharge energy density and discharge efficiency of glass-ceramic capacitor were achieved through a pulse charge-discharge circuit. The reduction of discharge efficiency with the increase of crystallization temperature is mainly caused by interfacial polarization. [ABSTRACT FROM AUTHOR]

In this work, an exergy analysis of discharging multi-tank thermal energy storage systems with constant heat extraction is studied. Theoretical models are developed to analyze the effect of the induced stratification through storage division into several tanks for different system configurations: multi-tank systems with even mass distribution, and two-tank systems with uneven and variable mass distribution. The instantaneous and the process efficiencies are defined to assess the performance of the system as function of operation parameters. For two- and four-tank systems with mass evenly distributed, efficiency increments around 4% and 7%, respectively, are possible. For two-tank systems, higher efficiencies are accomplished for short times when the mass is unevenly distributed and larger amount of the mass is in the hotter tank. For longer times, the even distributed mass situation provides the highest performance. To achieve superior efficiency of two-tank systems during the entire timespan, a time varying mass distribution χ = 0.5 ( 1 + e - 2 t ∗ ) is proposed. Finally, the energy losses as well as the pumping effects on the performance of one- and two-tank systems are analyzed. It is found that, both, the pumping effects and the energy losses are generally negligible and the efficiency can be improved dividing the storage system, rather than increasing the mass flow rate. [ABSTRACT FROM AUTHOR]