Minimum Energy Loss Research Articles

Shear Mode Ultrasonic Transducers from Flexible Piezoelectric PLLA Fibers for Structural Health Monitoring

AbstractShear mode guided waves are highly demanded for underwater structural health monitoring (SHM) applications due to their simplified non‐dispersive feature and minimal acoustic energy loss in the presence of liquid. Excitation and detection of pure shear wave are challenging using conventional piezoelectric materials used in the current ultrasonic transducers because they have complex piezoelectric responses mixed with multiple longitudinal, transverse, and shear modes. They also suffer from aging issue due to depoling. Here, conformable shear mode ultrasonic transducers are designed and made of flexible piezoelectric poly (L‐lactic acid) (PLLA) fibers on both flat and tubular structures. The electromechanical responses over a macroscopic area of the transducers are evaluated in a wide frequency range up to 500 kHz. The PLLA fiber‐based shear mode ultrasonic transducers exhibit a consistent sensitivity of detecting defects in liquid and air. In addition, the only shear mode in PLLA fibers originates from crystal structure without requiring electrical poling to render piezoelectricity, thus does not depole due to aging. The theoretical analyses including ab initio calculations and experimental results on both flat and tubular structures show the great potential of PLLA material and significant advantage of PLLA fiber‐based shear mode ultrasonic transducers for underwater SHM applications.

Dual Sub‐Cells Modification Enables High‐Efficiency n–i–p Type Monolithic Perovskite/Organic Tandem Solar Cells

AbstractMonolithic perovskite/organic tandem solar cells (POTSCs) have attracted increasing attention owing to ability to overcome the Shockley–Queisser limit. However, compromised sub‐cells performance limits the tandem device performance, and the power conversion efficiency (PCE) of POTSCs is still lower than their single‐junction counterparts. Therefore, optimized sub‐cells with minimal energy loss are desired for producing high‐efficiency POTSCs. In this study, an ionic liquid, methylammonium acetate (MAAc), is used to modify wide‐bandgap perovskite sub‐cells (WPSCs), and bathocuproine (BCP) is used to modify small‐bandgap organic solar cells. The Ac− group of MAAc can effectively heal the Pb defects in the all‐inorganic perovskite film, which enables a high PCE of 17.16% and an open‐circuit voltage (Voc) of 1.31 V for CsPbI2.2Br0.8‐based WPSCs. Meanwhile, the BCP film, inserted at the ZnO/organic bulk‐heterojunction (BHJ) interface, acts as a space layer to prevent direct contact between ZnO and the BHJ while passivating the surface defects of ZnO, thereby mitigating ZnO defect‐induced efficiency loss. As a result, PM6:CH1007‐based SOSCs exhibit a PCE of 15.46%. Integrating these modified sub‐cells enable the fabrication of monolithic n–i–p structured POTSCs with a maximum PCE of 22.43% (21.42% certified), which is one of the highest efficiencies in such type of POTSCs.

Design of a Saving-Energy Fuzzy Logic Controller for a Differential Drive Robot Based on an Optimization

In the problem of designing a Fuzzy Logic Controller (FLC) for robots in general and a Differential Drive Robot (DDR) in particular, the determination of the parameters of Membership Functions (MFs) and Fuzzy Rules (FRs) is a difficult, complicated, and time-consuming problem because this is mainly based on heuristics and the knowledge of experts. Therefore, this paper provides a new method to efficiently design an FLC for the DDR by using the Genetic Algorithm (GA). Here, the GA is used to generate and optimize both the parameters of MFs and the FRs according to the minimum kinetic energy loss criterion. For this purpose, a program is created in Google Colab® by using the Python language with the help of the “Pymoo” library to not only automatically generate all the suboptimal parameters of MFs and the suboptimal FRs but also the simulate and evaluate different used FLCs. This program is published as an open-source code so that all readers can browse, view, run, and modify the code themselves to design their FLC. The simulation results have shown that the designed FLC is much better than other used FLCs in terms of the minimum kinetic energy loss while other control performances are still good.

Electric Vehicle Wireless Charging using RFID

Electric vehicle (EV) wireless charging using radio-frequency identification (RFID) is a novel technology that enables the charging of electric vehicles without the need for wires or cables. The technology utilizes RFID tags that are installed on the EV, which communicate with the charging pad through electromagnetic fields. The charging process is initiated when the RFID reader detects the presence of the EV with the installed RFID tag, and the charging pad is activated. The power transfer is then enabled between the charging pad and the EV, allowing for the charging process to begin. RFID-based wireless charging technology offers numerous benefits over traditional wired charging systems. For instance, it eliminates the need for physical connectors, thereby reducing the wear and tear of components and increasing the convenience of charging. Moreover, the technology is more efficient, with minimal energy losses, and reduces the risk of electrical hazards. It also minimizes the impact of weather conditions and road debris on the charging process, making it suitable for both indoor and outdoor charging application. In conclusion, EV wireless charging using RFID is a promising technology that can potentially revolutionize the EV charging industry. It offers numerous benefits, including increased convenience, efficiency, and safety, and has the potential to significantly reduce the environmental impact of transportation.

Design parameters of water intake chambers on water supply channels of pumping stations

The research is devoted to improving the working conditions of chamber water intakes of pumping stations (PS) on water supply channels, which is one of the main factors determining the efficiency of operation of pumping units and stations. An analysis of the current state of the operating conditions of chamber water intakes according to field surveys and literary sources shows that the dimensions of the water intake chambers were assigned based on the minimum energy loss in the suction pipeline of the pump, which, in conditions of high turbidity of water, leads to siltation and complicates the operation of pumping stations. When the water intake chambers are silted, its hydraulic resistance increases, air vortex funnels are formed, the water supply of the pump decreases and the likelihood of cavitation phenomena increases. A significant amount of work has been devoted to the issues of improving the hydraulic characteristics of the flow in the fore chamber and water intake chambers. Therefore, without duplicating them, we conducted research to establish the effect of silting of the chambers on the value of the hydraulic resistance of the suction pipeline and to develop measures to improve the hydraulic characteristics of the intake chamber under conditions of operation in a suspension-carrying flow. To solve the problem, a laboratory stand was made that simulates hydraulic processes in natural conditions based on modeling methods, taking into account the preservation of the constancy of the main similarity criteria.

An Efficient Method for Heat Recovery Process and燭emperature燨ptimization

Flue gas heat loss accounts for a significant component of the overall heat loss for coal-fired boilers in power plants. The flue gas absorbs more heat as the exhaust gas temperature rises, which reduces boiler efficiency and raises coal consumption. Additionally, if the exhaust gas temperature is too high, a lot of water must be used to cool the flue gas for the wet flue gas desulfurization system to function well, which has an impact on the power plant’s ability to operate profitably. It is consequently vital to take steps to lower exhaust gas temperatures in order to increase boiler efficiency and decrease the amount of coal and water used. Desulfurization performance may be enhanced and water use can be decreased by reasonable flue gas characteristics at the entry. This study analyzed the unit’s energy consumption, investment, and coal savings while proposing four coupling strategies for regulating flue gas temperature and waste heat recovery. A graded flue gas conditioning and waste heat recovery plan was presented under the condition of ensuring high desulfurization efficiency, along with the notion of minimizing energy loss owing to energy inflow temperature difference. Numerical results show that the proposed methods improved the system performance and reduced the water consumption and regulated the boiler temperature.

First principles calculation of perovskite‐type hydrides KXH3 (X=Al, Cu) for hydrogen storage applications

The primary objective of this paper is to characterize the perovskite-type hydrides KXH3 (X=Al, Cu) and explore their potential for hydrogen storage applications using density functional theory (DFT). The study investigates various aspects such as structure, electronic and optical properties, stability, and hydrogen storage capabilities. To accomplish this, the study employs the Perdew–Burke–Ernzerhof-Generalized Gradient Approximation (PBE + GGA) functional. The KAlH3 compound is optimized in a cubic crystal structure, yielding lattice constants of 7.55 Å. On the other hand, KCuH3 is optimized in a tetragonal crystal structure with dimensions of a=b=11.14 Å and c=13.23 Å. These materials exhibit stability, as indicated by their negative formation energy. The electronic properties of KXH3 (X=Al, Cu) are thoroughly investigated, including the determination of bandgap, total density of states, and partial density of states. Notably, these structures exhibit a metallic character. The optical results reveal that these novel materials demonstrate minimal energy loss and high conductivity. Regarding hydrogen storage capabilities, the gravimetric hydrogen storage values for KXH3 (X=Al, Cu) compounds are found to be 4.38 and 2.86 wt%, respectively. These findings suggest that KAlH3 shows promise as a potential candidate for hydrogen storage applications.

Photovoltaic-based Distributed Generation Allocation in Distribution Network for Energy Loss Minimization

Nowadays, there is a global consensus that integrating renewable energy sources (RESs) is highly needed to meet the increasing electricity demand and reduce the overall carbon footprint of energy production. However, large-scale integration of RES-based distributed generation (DG) units often poses several technical challenges in the system from stability, reliability, and power quality perspectives. However, these problems are usually mitigated by the optimal integration of DG units in the distribution networks (DNs). In this regard, the optimal sizing and placement of the DGs are crucial. Otherwise, network performance will deteriorate. This paper proposes to apply a novel population-based technique called the dung beetle optimization (DBO) algorithm for the optimal allocation of Photovoltaic (PV) based DG units to minimize total active energy loss subject to equality and inequality constraints in the DN. A DBO is inspired by the behaviours of dung beetles, including ball-rolling, dancing, foraging, stealing, and reproducing. A standard 33-bus system has been used to demonstrate the proposed method's effectiveness. The simulation results and comparison with other techniques demonstrate our proposed approach's significant energy loss reduction and a suitable voltage profile.

Machine learning framework for the analysis and prediction of energy loss for non-fullerene organic solar cells

The efficiency of organic solar cells (OSCs) has been improved more than 19% recently with the development of non-fullerene acceptor materials. Further improvement is still attainable with the optimal combinations of donors and acceptors that provide minimal energy losses. In this work, a data-enabled machine-learning (ML) framework was employed to predict the energy losses in the polymer:non-fullerene acceptor based devices. Based on the collected experimental dataset, the prediction accuracies of various machine learning models were systematically compared by estimating mean absolute percentage errors (MAPE), root mean squared errors (RMSE), and person’s r coefficient. The Random Forest regression model showed the best performance in predicting the energy losses with a correlation coefficient of 0.83 and relative error in the range of 0 – 20%. The predictive ability of this model was further validated using the different parameters of devices with power conversion efficiency range of 6 – 18%. Three different donor–acceptor combinations were chosen for fabricating the photovoltaic devices to fit this model into practical devices and experimentally obtained energy loss values were compared with the predicted values. In addition, the device parameters with the molecular descriptors to understand the correlation and energy loss is highly correlated with the HOMO offset. This study demonstrates that the ML approach provide an effective method to predict and virtual screen of promising donor–acceptor pairs with minimal energy loss and would be useful for developing next-generation high performance solar cell materials.

Multisource–Multidestination Optimal Energy Routing in Static and Time-Varying Vehicular Energy Network

A vehicular energy network (VEN) uses electric vehicles (EVs) to transport energy across a wide geographical area. EVs can charge and discharge wirelessly at road junctions while moving and, thus, transfer energy between junctions. In this article, we propose a method to optimally route energy from multiple energy-supplying junctions to multiple energy-demanding junctions while minimizing energy loss in four different VEN scenarios: 1) a time-invariant VEN; 2) a VEN with time-varying vehicular flows and energy demands; 3) a VEN with time-varying vehicular flows and time-averaged demands; and 4) a VEN with significant storage capacities at junctions. The method employed to solve these scenarios is to model the VEN as a graph specific to each scenario, and then solve the generalized flow problem on the graph. Simulations are performed on all four scenarios and show that transmission efficiency improves when a small number of long vehicular routes are introduced, and when storage capacities at junctions increase. The error in approximating a time-varying VEN as a static VEN is also investigated.

Hybrid Battery Balancing System for Electric Drive Vehicles

In electric vehicles, cell and module voltage equalization plays a vital role in Battery Management System (BMS). The capacity, temperature, and aging imbalances in the cells and modules of electric vehicles battery packs restrict the amount of power that can be delivered to the vehicle. Spurred by this issue, we propose a new class of battery balancing systems, called hybrid balancing, capable of simultaneously equalizing battery capacity while enabling cost-effectiveness of cell-level passive balancing and module-level active balancing, modules consist of a number of cells connected in series, with cell-level passive balancing performed in a module, together with the module level switched capacitor that performs active balancing among the modules. The strategy is called hybrid balancing because it pursues goals beyond conventional state-of-charge equalization, including temperature and power capability equalization, and minimization of energy losses. Design details and MATLAB Simulink simulation results are provided for a hybrid balancing system implemented on a lithium-ion battery pack.

Self‐Assembled Amphiphilic Monolayer for Efficient and Stable Wide‐Bandgap Perovskite Solar Cells

AbstractThe applications of wide‐bandgap (WBG) perovskite solar cells (PSCs) are limited by their subpar efficiency and stability due to their high density of defects, especially those at interfaces. Theoretical analyses suggest a monolayer of molecules, which is of minimum thickness and, hence, minimum resistance across the interface, possessing multifunctional groups and a permanent dipole, should effectively passivate the defects and minimize energy losses at interfaces. Herein, a self‐assembled monolayer (SAM) composed of amphiphilic molecules is designed and assembled as the interface layer to reduce the energy loss and enhance interface coupling between the perovskite and hole transport layer. It is found that the SAM also builds a back surface field through a p‐type doping effect, which promotes hole extraction and suppress the carrier recombination. Consequently, a remarkable power conversion efficiency (PCE) of 20.4% in parallel with a high open‐circuit voltage up to 1.25 V is attained. Additionally, an indoor PCE of 38.7% is realized. Both are among the best in their respective categories. Moreover, an all‐perovskite tandem solar cell is configured, presenting a decent PCE of 23.2%. This work emphasizes the significance of WBG PSCs for optoelectronic applications and indicates the eminent effects of SAMs for optimization of WBG PSCs.

Optimum Parallel Processing Schemes to Improve the Computation Speed for Renewable Energy Allocation and Sizing Problems

The optimum penetration of distributed generations into the distribution grid provides several technical and economic benefits. However, the computational time required to solve the constrained optimization problems increases with the increasing network scale and may be too long for online implementations. This paper presents a parallel solution of a multi-objective distributed generation (DG) allocation and sizing problem to handle a large number of computations. The aim is to find the optimum number of processors in addition to energy loss and DG cost minimization. The proposed formulation is applied to a 33-bus test system, and the results are compared with themselves and with the base case operating conditions using the optimal values and three popular multi-objective optimization metrics. The results show that comparable solutions with high-efficiency values can be obtained up to a certain number of processors.

Experimental Study on the Lubrication Enhancement of Slider-on-Disc Contact by Stearic Acid Adsorption under Limited Lubricant Supply

The optimization of the lubricant supply quantity contributes to minimizing energy losses and wastage. To enhance the performance of hydrodynamic bearings running with limited lubricant supply (LLS), this study examined the effect of stearic acid as an additive. Stearic acid is commonly used for boundary lubrication as an organic friction modifier. How the stearic acid adsorption affects the hydrodynamic lubrication of a slider-on-disc contact under LLS was investigated using interferometry measurement and fluorescence observation in this study. Firstly, the oil reservoir of PAO10 with stearic acid adsorption was observed at the slider entrance. Secondly, the film thickness versus speed of PAO10 and PAO10 with 0.1% and 0.3% stearic acid, respectively, were measured. Finally, the morphology and surface properties of the glass and steel blocks with stearic acid adsorption were characterized by atomic force microscopy and Fourier transform infrared spectroscopy. The results show that the stearic acid adsorption layer weakens the wettability of the lubrication track and induces the ‘dewetting’ phenomenon of the lubricating oil. Thus, discrete oil distribution in the form of stripe or droplet can be generated, which leads to the accumulation of lubricating oil at the slider entrance to form a reservoir. An additional inlet pressure that is generated by the oil reservoir due to surface tension increases the oil film formation capacity. Furthermore, the morphologies of the adsorbed stearic acid layer on the glass and the steel blocks are, respectively, characterized by the nano-sized granular bulge and brush structure. This study reveals a new role of stearic acid adsorption in promoting LLS lubrication.

Impact study of integrating solar double chimney power plant into electrical grid

Integrating a novel design of Solar Double Chimney Power Plant system (SDCPPS) into a traditional medium voltage (MV)) distribution grid in the Safawi area, Jordan was presented. The impact of full-day integration of the maximum electrical energy on the performance indices of voltage profile (VP), power factor (PF), losses, and voltage step (VS) was assessed. The SDCPP operates under uniform electrical energy production even under varied weather conditions to generate 286.6 MWh/year. Connecting the SDCPP to the Medium Voltage (MV) point allows for electrical energy stabilization, minimizes energy losses, and maintains the allowable PF. The maximum reduction of voltage deviation (VD), and the average and maximum reduction in the losses were 0.93%, 0.34%, and 0.43%, respectively, The VS limit at the point of common coupling was within the 3% of the rated voltage. The PF dropped to 0.72 due to the increase of pure active power generated from the SDCPPS. Improving the combined PF is based on the BSP, which should be operated under 0.88 leading to keeping the SDCPPS running in the PF control mode as per connection code requirements. The performance of the SDCPPS has the edge over other renewable energy sources for all performance indices.

Development of effective shielding against electricity meters tampering with strong magnetic fields

• Different ways to locate and orient current transformers on the printed circuit board are considered. • Several rectangular and triangular shielding geometries are simulated and compared in terms of their effectiveness. • Effectiveness of multilayer shields with a gap between layers for flux shunting is estimated. • Recommendations towards effective shielding of the electric energy meters are introduced. To maintain high efficiency, electric utility providers aim to minimize energy losses between points of generation and customer distribution. A significant share of these losses is nontechnical, such as losses from energy theft. One prevalent method of energy theft involves tampering with electricity meters by means of strong magnetic fields. In this study, different shielding structures were developed to protect the electric energy meters’ pulse current transformers from external magnetic fields, with respect to the allocation and orientation of these sensitive elements. Several shielding geometries, solid and multilayer shields were modeled and compared in terms of their efficiency for flux shunting. Based on the obtained results, recommendations for effective shielding against tampering were driven.

Optimal Power Sharing Control of the Hybrid Energy Storage System of an Electric Vehicle Along a Standard Driving Cycle

Abstract The paper presents a strategy of energy loss minimization within a hybrid energy storage system of an electrical vehicle, composed by a battery and a supercapacitor. The optimization of the power sharing between these energy storage devices is performed for the New European Driving Cycle, using the Particle Swarm Optimization algorithm. The minimum energy storage required to pass through the driving cycle is taken into account as a time-variable constraint during the optimization. The dimension of the search space increases with the dimension of the optimization vector, which has to be kept low in order to keep the complexity of the problem manageable. It is shown, that the subdivision, and piecewise optimization of the driving cycle improves the result by means of relaxation of the constraint represented by minimum level of the required energy storage.

Graphical Prediction of Optimum Pinch Point Value with AEA Software Simulation and Validation Applied in Closed Cycle Gas Power Plant

Studying industries energy saving is very important prospect for many researchers in the last four decades. In this respect, better process heat transfer can be achieved to improve process operating and capital cost. Thereafter, obtaining higher amount of heat recovery, which will help to reach system optimum heat exchanger network design. Application of Pinch analysis (PA) in our current study, was found to be as an effective method towards economic solution and assessment for all system thermal processes. Whereby, minimizing energy losses, and thus, prediction of maximum energy saving. In addition, application of "Aspen Energy Analyzer (AEA)" simulation software assist our effort to optimize Heat Exchanger Network design (HEN), with various application scenario towards best design. This study represents a "Case study" as a Brayton closed cycle gas turbine power plant in Al-khairat district, which is one of a number of sites used to generate electricity for Iraq national grid. However, the plant original design is open cycle. This study, represent an attempt to apply (PA) in system closed cycle model with the same working conditions. The results predicted, on the contrary of open cycle, that using closed cycle (PA) with temperature difference ∆Tmin can be acceptable with several design propositions. The optimum (∆Tmin = 15℃) were evaluated in the closed cycle system pinch analysis, thereby the maximum Qrec. process that minimize the QHmin & QCmin requirement were identified by the software simulation for the best HEN design. These results were found as Qrec. = 318.330 MW, QHmin = 88.607 MW and QCmin =39.564 MW.

Structural, elastic, thermodynamic, electronic, magnetic, thermoelectric and optical investigation of chromate spinels TCr2O4 [T = V2+, Mn2+, Fe2+] for optoelectronic applications

Spinel oxides (TM2O4) containing transition metals are gaining vast momentum not only for advanced exploration of fundamental properties but also because of their potential as promising materials for various technological applications, such as microwaves, fuel cells, sensors, information storage, supercapacitors, magnetic fluids, photocatalysis and biomedical devices. In this regard, the structural, elastic, thermodynamic, electronic, magnetic, thermoelectric and optical properties of three related chromate spinels (TCr2O4) with 3d transition metals (T2+ = V, Mn, Fe) have been systematically investigated. The Perdew-Burke-Ernzerh (PBE) functional and the exchange-correlation method (PBE + U) based on the generalized gradient approximation were used to investigate these properties. The elastic parameters confirm that TCr2O4 compounds are mechanically stable and possess stiffness and anisotropic properties. The calculated band structures, DOSs and magnetic moments show that the cubic TCr2O4 (Fd-3m) are half-metallic (HM) ferromagnetic compounds due to strong hybridization between their T-3d, Cr-3d and O-2p states. The thermodynamic properties are explained by calculating the melting temperature (Tm), average sound velocity (vm) and Debye temperature (ƟD). High values of these parameters, Tm, νm and ƟD, indicate the high thermodynamic stability of TCr2O4, which allows them to maintain their ground state structures at high temperatures. The thermoelectric properties as a function of temperature illustrate the stability of the current spinel structures. We have also calculated the optical properties, including real ε1(ω) and imaginary ε2(ω) parts of dielectric function ε(ω), conductivity σ(ω), absorption coefficient α(ω), reflectivity R(ω), refractive index n(ω), extinctive index k(ω) and energy loss function L(ω). TCr2O4 exhibits high dielectric constants; low reflectivity and minimal energy loss in the range VL-UV, making these FM-HM compounds promising materials for many optoelectronics devices.

Relative enlargement of the medial preoptic nucleus in the Etruscan shrew, the smallest torpid mammal

Endothermy is a key feature of mammalian biology and enables mammals to maintain stable body temperature and homeostatic functions in the face of a rapidly changing environment. However, when faced with harsh environmental conditions, certain mammalian species enter torpor, a state characterized by reduced metabolism, body temperature, and activity, to minimize energy loss. Etruscan shrews are the smallest mammals, with a surface-to-volume ratio that is very unfavorable for endothermic animals. As a result, Etruscan shrews have an extremely high metabolic rate and are known to enter torpor frequently, presumably as an energy-saving measure. Despite the recent identification of medial preoptic area (MPA) as a key brain region to regulate torpor in mouse, little is known about neural control of torpor in other endothermic animals, including the Etruscan shrew. Here, we confirmed that Etruscan shrews readily enter torpor even in the absence of strong physiological triggers. We then compared the medial preoptic nucleus (MPN) within the MPA of Etruscan shrew and rat, a mammal that does not enter torpor under physiological conditions. While rats have roughly 100 times the body weight and 33 times the brain weight of Etruscan shrews, we find that the male rat MPN exhibits only 6.7 times the volume of that of the male Etruscan shrew. Accordingly, the relative brain volume of the MPN was 6.5-fold larger in shrews, a highly significant difference. Moreover, MPN neuron counts were only roughly twofold lower in shrews than in rats, an astonishing observation considering the interspecies size difference and that neocortical neurons are ~ 20 × more numerous in rats than in shrews. We suggest that the extraordinary enlargement of the Etruscan shrew MPN is a specialization for orchestrating torpor in a mammal with an exceptional metabolism.