Initial Power Research Articles

Microwave–osmotic–vacuum combination drying of mango cubes with maltodextrin moderated sucrose solution

A microwave–osmotic–vacuum combination drying technique was used to evaluate the effect of processing factors such as temperature and concentration with 15% inclusion of maltodetrin (dextrose equivalent, DE 10) during the microwave osmotic drying under continuous medium spray flow (MWODS) and power level during finish microwave vacuum drying (MVD). Moisture loss (ML), solids gain (SG), ML/SG ratio, weight reduction (WR), bulk density (BD), rehydration capacity (RC), drying times, and quality parameters, total color difference (ΔE), texture (hardness and chewiness) were evaluated during the process to assess the product quality. Drying conditions were optimized to maximize ML, ML/SG, WR, BD, RC and minimize ΔE, hardness, chewiness, and drying times. Optimum levels were found at 58.5 °C temperature, 50.0% concentration, and 30 min contact time during MWODS and 20% initial power up to 50% moisture content and 10% final power level to the final moisture content of 20% (32 min). In addition to MVD, freeze drying, vacuum and air drying were also used for comparison for finish drying. Overall, the MWODS with maltodextrin moderated sucrose as solute and MVD for finished drying resulted in better product quality and remained closest to the freeze dried samples.

Computer Simulation of Multichannel Beam Focusing System in Turbulent Atmosphere

The results of a computer simulation of laser beams focused by a combined multichannel array system in the atmosphere are presented. Beam propagation on atmospheric paths is considered taking into account the influence of turbulence and time-dependent thermal blooming interactions. The increase in the maximum intensity of the focal spot due to the optimization of the initial power density of the emitting aperture is estimated. It is shown that the scaling of the optimal initial power in multichannel arrays preserves the proportional dependence of the maximum intensity in focus with an increase in the number of channels. For wave-optics simulation, custom made software was developed based on the split-step method and modified for parallel algorithms using the functions of the Intel ® Math Kernel Library.

Precursor Engineering of Lead Acetate-Based Precursors for High-Open-Circuit Voltage Wide-Bandgap Perovskite Solar Cells.

Wide-bandgap (WBG) perovskites have great potential for inclusion in efficient tandem solar cells, but large open-circuit voltage losses have limited device performance to date. Here, we show that a high-quality WBG perovskite, FA0.83Cs0.17Pb(I0.8Br0.2)3, with enlarged grain sizes and improved crystallinity can be achieved by incorporating lead chloride (PbCl2) into a lead acetate (PbAc2)-based precursor. The improved film quality resulted in the suppression of nonradiative recombination and a reduction in defect density. Efficient WBG perovskite solar cells (1.66 eV) with an efficiency of 19.3% and a high Voc of 1.22 V were fabricated using a facile one-step spin-coating method without the need for an antisolvent. Notably, the unencapsulated devices retained 90% of their initial power conversion efficiency after storage in a dry box (10% humidity) for 800 h.

Predicting the Blockchain Technology Acceptance in Supply Chains with Inter-Firm Perspective: An Integrated DEMATEL and PLS-SEM Approach

Predicting the Blockchain Technology Acceptance in Supply Chains with Inter-Firm Perspective: An Integrated DEMATEL and PLS-SEM Approach

Evaluation of a proposed barium di-silicide tandem solar cell using TCAD numerical simulation

Barium di-silicide (BaSi2) material has attracted noteworthy interest in photovoltaics, thanks to its stability, abundant nature, and excellent production feasibility. In this current work, a two-terminal (2T) monolithic all-BaSi2 tandem solar cell is proposed and explored through extensive TCAD simulation. A BaSi2 bottom sub-cell with a bandgap of 1.3 eV, and a Ba(CxSi1−x)2 top sub-cell with a tunable bandgap are employed in the design. It was found that a bandgap of 1.8 eV, which corresponds to x = 0.78, is the optimum choice to obtain the maximum initial power conversion efficiency (η) of 30%. Then, the tandem performance is optimized by investigating the impact of doping and the thickness of both absorber layers. Further, the current matching point is monitored whilst altering the thickness of the top cell resulting in η = 32.83%%, and a short-circuit current density (Jsc) of 16.47 mA/cm2. Additionally, we have explored the influence of the defect density in the absorbers, and the work function of contacts on the performance parameters. All TCAD simulations are accomplished using the Silvaco Atlas package under AM1.5G illumination.

Power System Restoration With Renewable Participation

Power system restoration requires initial power sources to restart generators, energizing transmissions, and pick up critical loads. Sufficient initial power capacity is critical for restoration success and reducing outage duration. Due to the reliability requirement and high standby costs, black-start resources are scarce and expensive in areas where hydro power is not available. Variable renewable energy (VRE), whose fast-ramping capability and economical standby costs are suitable for black-start, is traditionally excluded from participation in system restoration because its uncertainty and variability could cause severe disturbance to the system that is already fragile during restoration. Recently, VRE is becoming a potential participant in system restoration as auxiliary black-start resources. This work will explore the potential benefits of renewable energy in restoration and potential ways for VRE to participate in system restoration. We propose two dispatch models for wind participation. The uncertainty of wind generation is handled by probabilistic constraints to guarantee a feasible restoration plan with a high probability. We perform computational experiments to demonstrate the effectiveness of proposed models and benefits of renewable participation in restoration with the two approaches.

Effect of Self-Focusing on Propagation of a Laser Beam in the Atmosphere Along a Slant Path

The equivalent B-integral phase screen (EBPS) method of numerical simulation is proposed to study the propagation of a high-power laser beam in the atmosphere along a slant path, and the computational accuracy and efficiency of the EBPS method are confirmed. It is shown that a decrease of the self-focusing caused by the atmosphere refraction effect. However, the refraction correction for the elevation angle is hardly affected by the self-focusing effect. On the other hand, the analytical expressions of the B integral and the optimal initial beam power of a high-power laser beam propagating in the atmosphere along a slant path are derived. It is found that the optimal beam power and the target maximum intensity decrease as the apparent elevation angle decreases, while the optimal beam power decreases but the target maximum intensity increases as the wavelength decreases. A method to optimize the beam quality on the target is presented.

Stackelberg Game for Secure CR-NOMA Networks Against Internal Eavesdropper

The combination of CR-NOMA has enormous potential interest to improve spectral efficiency and increase system capacity in future wireless communication networks. Hence, according to the broadcast nature of the CR-NOMA wireless channel, handling the confidentiality of information is one of the most important requirements of the network. In this paper, PLS against internal Eve is investigated by the CR-NOMA under the limitations of joint delay and confidentiality rate. First, initial power allocation for SU based on the PU interference threshold is constructed. Then, a multi-objective problem based on different SUs demands is formulated based on Stackelberg game modeling. After that, the SE is studied and explored. At the final stage, an overall algorithm has been proposed whereby SE strategies are frequently updated to find the best parameters for the proposed system model. The simulation results show the superiority of the proposed scheme in achieving a higher average utility function, spectral efficiency, fairness index, up to 44%, 90%, and 54.7%, respectively, and reliability compared to the conventional scheme.

A note on power plant selection for engineered geothermal systems

An initial study has been carried out to determine the most suitable system for recovering power from engineered geothermal systems. When using a binary power plant, account has been taken of the relatively rapid temperature decline of such resources. A simplified idealised analysis shows that the total recoverable power is more or less independent of the type of power plant used but a system that maximises the heat recovery from the brine, in its passage through the primary heat exchanger will yield a much higher initial power output and a much quicker return on the capital invested, than one which is designed to maximise the power plant cycle efficiency.

Synergistic Ionic Liquid in Hole Transport Layers for Highly Stable and Efficient Perovskite Solar Cells.

Perovskite solar cells (PSCs) with n-i-p structures often utilize an organic 2,2',7,7'-tetrakis (N, N-di-p-methoxyphenyl-amine) 9,9'-spirobifluorene (spiro-OMeTAD) along with additives of lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI) and tert-butylpyridine as the hole transporting layer (HTL). However, the HTL lacks stability in ambient air, and numerous defects are often present on the perovskite surface, which is not conducive to a stable and efficient PSC. Therefore, constructive strategies that simultaneously stabilize spiro-OMeTAD and passivate the perovskite surface are required. In this work, it is demonstrated that a novel ionic liquid of dimethylammonium bis(trifluoromethanesulfonyl)imide (DMATFSI) could act as a bifunctional HTL modulator in n-i-p PSCs. The addition of DMATFSI into spiro-OMeTAD can effectively stabilize the oxidized spiro-OMeTAD+ cation radicals through the formation of spiro-OMeTAD+ TFSI- because of the excellent charge delocalization of the conjugated CF3 SO2 - moiety within TFSI- . In addition, DMA+ cations could move toward the perovskite from the HTL, resulting in the passivation of defects at the perovskite surface. Accordingly, a power conversion efficiency of 23.22% is achieved for PSCs with DMATFSI and LiTFSI co-doped spiro-OMeTAD. Moreover, benefiting from the improved ion migration barrier and hydrophobicity of the HTL, still retained nearly 80% of their initial power conversion efficiency after 36 days of exposure to ambient air.

Prospective Validation of Tubomanometry in Children With Normal Eustachian Tube Function.

Tubomanometry (TMM), described initially by Estève, is a relatively new manometric method for testing the eustachian tube function (ETF). This study presents the analysis of the measurement of ETF of healthy children by TMM, which has, to date, not been properly evaluated. The objectives of the study were to establish normative data for TMM and to demonstrate TMM as a reliable and valid method for measuring ETF in children. The evaluation, after initial power analysis, comprised 35 children from 6 to 15 years of age with an intact tympanic membrane, no severe ET dysfunction, and less than three inflammations of the middle ear in their medical history. TMM was performed twice at three pressure levels for both ears. Statistical assessment of the various parameters of TMM was performed with emphasis on the R value and possible age dependency. The 90th percentile for the R value was calculated to be 1.12. No clinically relevant age effect regarding the use of TMM as a screening method for children was found. Healthy children showed an opening within normal limits for the so-called R value in 88%; a delayed opening was measured in 6%, and rarely no opening was measured in 2%. TMM is a reliable tool for measuring ETF in children. The normal limit for the R value should be set at 1.12. The proposed measuring algorithm and results can be used to calculate sensitivity and specificity in a future study.

Network Reconfiguration for Power Loss Reduction on Distribution feeder Using Particle Swarm Optimisation: Case study of 11kv feeder in Ilorin, Nigeria

The distribution system is the largest segment of the electrical power system and the final stage in delivering electricity to consumers. It experiences power losses which could be technical or non-technical due to its radial configuration and connected components. Technical losses occur as energy dissipation in the form of heat in the system components, which is unavoidable. It affects the efficiency of the system and increases operational costs. Therefore, the reduction is essential for adequate power supply and improvement in utility revenue generation. This study focuses on reducing power losses on 11 kV Taiwo distribution feeder in Ilorin using the Network reconfiguration approach. The feeder was modelled, and its power losses were evaluated based on the Backward Forward Sweep method suitable for the radial network. The reconfigured network was optimised using the Particle Swarm Optimisation technique. The study shows that the values of feeder real power losses before and after reconfiguration are 176.883 kW and 121.972 kW, respectively.Further improvement was, however, achieved when PSO was used for the reconfiguration, as the power loss value stands at 98.465 kW. This is 44.33 % reduction compared to the initial power loss value and 19.273 % after reconfiguration. Furthermore, the values of the reactive power losses before and after reconfiguration are 9.474 kVar and 6.527 kVar, respectively, amounting to a 31.11 % reduction. However, PSO reduces the value to 3.101 kVar, which is 67.27 % of the initial value. Thus, radial distribution network reconfiguration using PSO has proven to be a robust method for reducing power loss in the distribution network.

Inhibited Crack Development by Compressive Strain in Perovskite Solar Cells with Improved Mechanical Stability.

Metal halide perovskites are promising as next-generation photovoltaic materials, but stability issues are still a huge obstacle to their commercialization. Here, the formation and evolution of cracks in perovskite films during thermal cycling, which affect their mechanical stability, are investigated. Compressive strain is employed to suppress cracks and delamination by in situ formed polymers with low elastic modulus during crystal growth. The resultant devices pass the thermal-cycling qualification (IEC61215:2016), retaining 95% of the initial power conversion efficiency (PCE) and compressive strain after 230 cycles. Meanwhile, the p-i-n devices deliver PCEs of 23.91% (0.0805 cm2 ) and 23.27% (1 cm2 ). The findings shed light on strain engineering with respect to their evolution, which enables mechanically stable perovskite solar cells.

Self‐Healable and Stretchable PAAc/XG/Bi2Se0.3Te2.7 Hybrid Hydrogel Thermoelectric Materials

Thermoelectric power generators have attracted increasing interest in recent years owing to their great potential in wearable electronics power supply. It is noted that thermoelectric power generators are easy to damage in the dynamic service process, resulting in the formation of microcracks and performance degradation. Herein, we prepare a new hybrid hydrogel thermoelectric material PAAc/XG/Bi2Se0.3Te2.7 by an in situ polymerization method, which shows a high stretchable and self‐healable performance, as well as a good thermoelectric performance. For the sample with Bi2Se0.3Te2.7 content of 1.5 wt% (i.e., PAAc/XG/Bi2Se0.3Te2.7 (1.5 wt%)), which has a room temperature Seebeck coefficient of −0.45 mV K−1, and exhibits an open‐circuit voltage of −17.91 mV and output power of 38.1 nW at a temperature difference of 40 K. After being completely cut off, the hybrid thermoelectric hydrogel automatically recovers its electrical characteristics within a response time of 2.0 s, and the healed hydrogel remains more than 99% of its initial power output. Such stretchable and self‐healable hybrid hydrogel thermoelectric materials show promising potential for application in dynamic service conditions, such as wearable electronics.

Modelling the induction, thrust and power of a yaw-misaligned actuator disk

Collective wind farm flow control, where wind turbines are operated in an individually suboptimal strategy to benefit the aggregate farm, has demonstrated potential to reduce wake interactions and increase farm energy production. However, existing wake models used for flow control often estimate the thrust and power of yaw-misaligned turbines using simplified empirical expressions that require expensive calibration data and do not extrapolate accurately between turbine models. The thrust, wake velocity deficit, wake deflection and power of a yawed wind turbine depend on its induced velocity. Here, we extend classical one-dimensional momentum theory to model the induction of a yaw-misaligned actuator disk. Analytical expressions for the induction, thrust, initial wake velocities and power are developed as a function of the yaw angle ( $\gamma$ ) and thrust coefficient. The analytical model is validated against large eddy simulations of a yawed actuator disk. Because the induction depends on the yaw and thrust coefficient, the power generated by a yawed actuator disk will always be greater than a $\cos ^3(\gamma )$ model suggests. The power lost due to yaw misalignment depends on the thrust coefficient. An analytical expression for the thrust coefficient that maximizes power, depending on the yaw, is developed and validated. Finally, using the developed induction model as an initial condition for a turbulent far-wake model, we demonstrate how combining wake steering and thrust (induction) control can increase array power, compared to either independent steering or induction control, due to the joint dependence of the induction on the thrust coefficient and yaw angle.

Running-In Effects of Lubricated Polyether Ether Ketone on Steel for Different Spreading and Sorption Tendencies

Polyether ether ketone is a highly resilient thermoplastic that can withstand as an unfilled or filled polymer tribological high loads in high-temperature applications, as it has a high glass and melting temperature. Currently, it attracts interest as a lubricated material for drive systems to minimize noise, as a lightweight solution improving the CO2 balance, or in combination with novel lubricants. We have produced friction and wear maps with pin-on-disk tests on steel axial bearing rings and investigated the interaction and running-in behavior with different lubricants, such as different polyalkylene glycols, polyalphaolefin, and various esters. In general, the behavior of polyether ether ketone is hardly influenced by the frictional heat when loaded at room temperature. It shows a lubricant-specific polymer transfer and surface softening. This running-in impact is enhanced if a loading strategy with initial high friction power is applied. The beneficial transfer forms on the track in mixed lubrication on the rough counterpart until an increasing adhesive contact limits this effect. The appearance of a minimal wear coefficient was found below the glass temperature with lubricants strongly sorbing in polyether ether ketones, such as polar polyalkylenglycol or trimellitic acid ester-based lubricants. Using the interfacial energy of the system to derive an energy term describing the tendency to form a stable transfer, systematic trends in the tribological behavior of polyether ether ketone and polyketone could be identified that can be projected on other systems.

An Efficient Grid-Based Geocasting Scheme for Wireless Sensor Networks

In a wireless sensor network (WSN), geocasting is a location-based routing protocol used for data collection or information delivery. In geocasting, a target region usually contains many sensor nodes with limited battery capacity, and sensor nodes in multiple target regions need to transmit data to the sink. Therefore, how to use location information to construct an energy efficient geocasting path is a very important issue. FERMA is a geocasting scheme for WSNs based on Fermat points. In this paper, an efficient grid-based geocasting scheme for WSNs, which is called GB-FERMA, is proposed. The scheme uses the Fermat point theorem to search for the specific nodes as Fermat points in a grid-based WSN, and it selects the optimal relay nodes (gateways) in the grid structure to realize energy-aware forwarding. In the simulations, when the initial power 0.25 J, the average energy consumption of GB-FERMA is about 53% of FERMA-QL, 37% of FERMA, and 23% of GEAR; however, when with the initial power 0.5 J, the average energy consumption of GB-FERMA is about 77% of FERMA-QL, 65% of FERMA, and 43% of GEAR. The proposed GB-FERMA can effectively reduce the energy consumption and thus prolong the lifetime of the WSN.

Enhanced performance of planar perovskite solar cells by doping the SnO2 electron transport layer with guanidinium chloride

Tin (IV) oxide is a highly promising electron transport layer (ETL) for lead halide perovskite solar cells due to its high conductivity, transparency, wide band gap, and the possibility of low-temperature processing. Nonetheless, charge carrier recombination processes at the SnO2/perovskite interface diminish the device performance. Here, we demonstrate that SnO2 doping with guanidine hydrochloride (G-SnO2) leads to efficient surface passivation and a larger band offset between the ETL and the perovskite layer, resulting in reduced voltage losses and faster electron transfer. Moreover, G-SnO2 facilitates the growth of highly crystalline perovskite layers. Consequently, a power conversion efficiency of up to 23.48% and a high open-circuit voltage of 1.18 V are obtained in solar cells incorporating the G-SnO2 ETL. These devices also exhibited negligible hysteresis and maintained more than 96% of their initial power conversion efficiency after 1,250 h exposure to the air without encapsulation.

Design and Development of an Electromagnetic Catapult for Life-Saving Projectile

In this article, a kind of electromagnetic coil catapult for life-saving projectile (LSP) is designed and developed for water rescue. We adopted the single-stage coil launcher scheme to save costs and improve reliability. Two launch modes, armature-load integrated launch (ALIL) and armature-load separated launch (ALSL), are compared by simulation. In the ALIL mode, LSP and armature are integrated together. The LSP will be decelerated due to the armature drag effect after being launched to the maximum speed. In the ALSL mode, the armature will separate from the LSP after reaching the maximum speed due to the electromagnetic drag force. The LSP will fly out of the catapult at peak speed due to inertia, which will improve the muzzle speed of the LSP compared with the ALIL. Further analysis shows that in the ALSL mode, reducing the initial power supply voltage, reducing the armature-load mass ratio, and increasing the number of coil turns are beneficial to the armature recovery. The armature recovery method can make the armature reusable. A set of electromagnetic catapult devices for LSP is developed. Finally, armature launch and LSP launch tests are carried out. It is proven that the simulation and test results are consistent. Under the full voltage state, the catapult can make the LSP obtain a muzzle speed of 52 m/s, and the throw distance exceeds 180 m. The armature can be recovered and reused. Experiments verify the feasibility of the electromagnetic catapult for LSP, which has good application value.

Tapered Optical Fiber Sensor Coated with Single-Walled Carbon Nanotubes for Dye Sensing Application

The present study aimed to improve the optical sensing performance of tapered optical fiber sensors toward aqueous Rhodamine B solution of different concentrations by applying single-walled carbon nanotubes (SWCNTs). The functional coating was formed on the surface of the tapered optical fiber sensor using an aerosol layer-by-layer deposition method. Before deposition, the SWCNTs were processed with multistage liquid-phase treatment in order to form a stable dispersion. The effect of SWCNT treatment was investigated through Raman spectroscopy. The deposition of 220 layers caused a reduction of up to 60% of the initial optical power of radiation propagating through the optical fiber core. The optical fiber sensor coated with SWCNTs demonstrated significantly higher sensitivity compared to a non-coated sensor in the range of 2-32 mg/L of Rhodamine B concentration in an aqueous solution. The experimental results demonstrated that the sensitivity was increased 10 times from 32 (mg/L)-1, for the non-coated sensor, up to 317 (mg/L)-1 after SWCNT coating deposition. Moreover, the SWCNT-coated sensor demonstrated high repeatability that allowed for the evaluation of the concentration regardless of the previously analyzed dye concentration.