Low power efficiency is a deficiency in traditional Orthogonal Frequency Division Multiplexing(OFDM)systems.To counter this problem,a new wireless transmission technology based on Zero-Padding Carrier Interferometry O...Low power efficiency is a deficiency in traditional Orthogonal Frequency Division Multiplexing(OFDM)systems.To counter this problem,a new wireless transmission technology based on Zero-Padding Carrier Interferometry OFDM(ZP-CI/OFDM)is proposed.In a ZP-CI/OFDM system,transmission symbols are spread to all OFDM subcarriers via carrier interferometry codes.This reduces the Peak-to-Average Power Ratio(PAPR)that traditional OFDM suffers and also exploits frequency diversity gain.By zero-padding at the transmitter,advanced receiver technologies can be adopted for ZP-CI/OFDM so that frequency diversity gain can be further utilized and the power efficiency of the system is improved.展开更多
Carbazole derivatives with a single phosphonic acid(PA)group are widely used as monolayer interfaces in perovskites and organic solar cells(OSCs).However,their hydrophilic nature renders ITO electrodes hydrophobic,lim...Carbazole derivatives with a single phosphonic acid(PA)group are widely used as monolayer interfaces in perovskites and organic solar cells(OSCs).However,their hydrophilic nature renders ITO electrodes hydrophobic,limiting further applications.In this study,a novel carbazole-based compound functionalized with two PA groups,denoted 2PACz-D1,was designed to create a dual hydrophilic interface.This configuration enables the formation of a bilayer hole-transporting layer(HTL).Specifically,one PA group anchors to the ITO electrode,while the other generates a secondary hydrophilic surface.This allows the subsequent deposition of hydrophilic PEDOT:PSS,forming a protective bilayer HTL that shields ITO from corrosive acidic polymers.The OSCs incorporating this bilayer HTL achieved a power conversion efficiency of 19.44%and exhibited improved thermal stability compared to devices with a single HTL.This work demonstrates the potential of bis-PA carbazole derivatives for tailoring the HTL surface properties,offering promising opportunities for various organic electronic devices.展开更多
The use of alternative fuels to generate mechanical and thermal energy in engines is a promising and sought-after technological area with its own unique advantages and characteristics.Consequently,enhancing the techni...The use of alternative fuels to generate mechanical and thermal energy in engines is a promising and sought-after technological area with its own unique advantages and characteristics.Consequently,enhancing the technical,economic,and environmental efficiency of gas engines fueled by propane-butane mixture and syngas through optimized operating cycle parameters(including valve timing,ignition timing angle,fuel mixture composition,and compression ratio)is a pressing imperative for scientific and energy sectors.The aim of the study was to investigate and compare the performance of an engine with different compression ratios running on a propane-butane mixture and laboratory syngas.The research’s primary originality lies in its joint study of syngas production technology and the evaluation of the efficiency of a mini power plant fueled by the resulting gas and conventional gas.This article presents a description of the experimental setup,data on measuring instruments,technical characteristics of the mini-power plant,the process for obtaining laboratory syngas,the properties of the gaseous fuels used,and experimental methods.Data on air and fuel consumption,as well as engine efficiency at different compression ratios when running on a propane-butane mixture and syngas,were obtained and analyzed.Converting an engine from a propane-butane mixture to syngas results in a reduction in power of almost 30% and efficiency by 13%–33%.Increasing the compression ratio by 0.9 units causes a rise in maximum efficiency from 0.177 to 0.235 for an engine running on a propane-butane mixture and an increase in maximum efficiency from 0.136 to 0.161 for a syngas engine.It has been confirmed that the compression ratio significantly impacts the technical and economic performance of an engine running on gaseous fuel.The obtained results can be used to modernize existing engines for operation on alternative fuels(syngas)and to design new mini-power plants with promising technical,economic,and environmental characteristics.展开更多
A low power high performance Delta-Sigma modulator for portable measurement applications is presented.To reduce power consumption while maintaining high performance,a fully feedforward architecture with a comprehensiv...A low power high performance Delta-Sigma modulator for portable measurement applications is presented.To reduce power consumption while maintaining high performance,a fully feedforward architecture with a comprehensive system-level design is implemented.As a key building block,a novel power efficient current mirror operational transconductance amplifier(OTA)with a fast-settling less-error switched-capacitor common-mode feedback(SC CMFB)circuit is introduced,and the effects of both gain nonlinearity and 1/f noise of OTA are discussed.A new method to determine the voltage gain of an OTA is also proposed.The bottom terminal parasitic effect of poly-insulator-poly(PIP)capacitors is considered.About an extra 20%of capacitance is added to the total capacitance load.A power and area efficient resonator is adopted to realize a coefficient of 1/90 for 50%power and 75%area reduction compared with conventional designs.The chip is implemented in a low cost 0.35μm complementary metal oxide semiconductor(CMOS)process.The total power consumption is 20μW with a 1.5 V supply,and the measured dynamic range(DR)is 95 dB over a 1 kHz bandwidth.Experimental results show that a high figure-of-merit(FOM)is achieved for the designed modulator in comparison with those from the literature.展开更多
The analysis and design of a semi-passive radio frequency identification（RFID） tag is presented.By studying the power transmission link of the backscatter RFID system and exploiting a power conversion efficiency mod...The analysis and design of a semi-passive radio frequency identification（RFID） tag is presented.By studying the power transmission link of the backscatter RFID system and exploiting a power conversion efficiency model for a multi-stage AC-DC charge pump,the calculation method for semi-passive tag＇s read range is proposed.According to different read range limitation factors,an intuitive way to define the specifications of tag＇s power budget and backscatter modulation index is given.A test chip is implemented in SMIC 0.18μm standard CMOS technology under the guidance of theoretical analysis.The main building blocks are the threshold compensated charge pump and low power wake-up circuit using the power triggering wake-up mode.The proposed semi-passive tag is fully compatible to EPC C1G2 standard.It has a compact chip size of 0.54 mm^2,and is adaptable to batteries with a 1.2 to 2.4 V output voltage.展开更多
A polymeric nanopore membrane with selective ionic transport has been proposed as a potential device to convert the chemical potential energy in salinity gradients to electrical power. However, its energy conversion e...A polymeric nanopore membrane with selective ionic transport has been proposed as a potential device to convert the chemical potential energy in salinity gradients to electrical power. However, its energy conversion efficiency and power density are often limited due to the challenge in reliably controlling the size of the nanopores with the conventional chemical etching method. Here we report that without chemical etching, polyimide （PI） membranes irradiated with GeV heavy ions have negatively charged nanopores, showing nearly perfect selectivity for cations over anions, and they can generate electrical power from salinity gradients. We further demonstrate that the power generation efficiency of the PI membrane approaches the theoretical limit, and the maximum power density reaches 130m W/m2 with a modified etching method, outperforming the previous energy conversion device that was made of polymeric nanopore membranes.展开更多
Considering that perfect channel state information(CSI) is difficult to obtain in practice,energy efficiency(EE) for distributed antenna systems(DAS) based on imperfect CSI and antennas selection is investigated in Ra...Considering that perfect channel state information(CSI) is difficult to obtain in practice,energy efficiency(EE) for distributed antenna systems(DAS) based on imperfect CSI and antennas selection is investigated in Rayleigh fading channel.A novel EE that is defined as the average transmission rate divided by the total consumed power is introduced.In accordance with this definition,an adaptive power allocation(PA) scheme for DAS is proposed to maximize the EE under the maximum transmit power constraint.The solution of PA in the constrained EE optimization does exist and is unique.A practical iterative algorithm with Newton method is presented to obtain the solution of PA.The proposed scheme includes the one under perfect CSI as a special case,and it only needs large scale and statistical information.As a result,the scheme has low overhead and good robustness.The theoretical EE is also derived for performance evaluation,and simulation result shows the validity of the theoretical analysis.Moreover,EE can be enhanced by decreasing the estimation error and/or path loss exponents.展开更多
With the continuous improvement of photovoltaic efficiency in the organic photovoltaic(OPV),interface engineering has emerged as a pivotal issue in their practical deployment.Currently,the robust crystallinity of smal...With the continuous improvement of photovoltaic efficiency in the organic photovoltaic(OPV),interface engineering has emerged as a pivotal issue in their practical deployment.Currently,the robust crystallinity of small molecule electron transport layers(ETLs)and the poor film-forming abilities of conjugated polymer ETLs are a huge obstacle in this field.Herein,an innovative and efficient nonconjugated polymer ETL,namely PNDI-SO,which contains polar cationic segments for solubility and conjugated units for efficient charge transport in stable OPV cells,is reported.Endowed with suitable energy levels and excellent electron extraction capabilities,PNDI-SO-based OPV cells attain a power conversion efficiency(PCE)of 18.54%.Furthermore,compared with conventional OPV cells utilizing PFN-Br or PDINN,PNDI-SO substantially enhances long-term stability under continuous illumination,evidenced by a T80 lifetime(signifying retention of 80% of initial performance)exceeding 1250 h.Notably,through scanning electron microscope,we verified that PNDI-SO achieves a harmonious balance between film-forming ability and charge transport properties for ETL,enabling the blade-coating OPV based on PBDB-TF:BTP-eC9 to achieve a PCE of 17.47%.These results suggest the potential of PNDI-SO as a promising interface material for industrial printing applications in OPV fabrication.展开更多
Driven by rapid advancements in smart wearable technologies and perovskite photovoltaics,flexible perovskite solar cells(FPSCs)have emerged as highly promising autonomous power sources,poised to transform the next gen...Driven by rapid advancements in smart wearable technologies and perovskite photovoltaics,flexible perovskite solar cells(FPSCs)have emerged as highly promising autonomous power sources,poised to transform the next generation of mobile energy systems,portable electronics,and integrated wearable devices.For successful deployment in real-world scenarios,FPSCs must exhibit a combination of key attributes,including high power conversion efficiency,lightweight architecture,environmental robustness,and mechanical adaptability-encompassing flexibility,stretchability,and twistability.This review provides a detailed examination of the evolution,current state,and practical deployment of FPSCs,emphasizing their potential as efficient,portable energy solutions.It investigates advanced strategies for improving environmental resilience and mechanical recoverability,including the engineering of flexible substrates,deposition of high-quality perovskite films,and optimization of charge-selective interfaces.Additionally,it offers a systematic analysis of device design,fabrication protocols,scalable printing techniques,and standardized performance evaluation methods tailored for wearable FPSCs.Recent progress in enhancing the optoelectronic properties and mechanical durability of FPSCs is also critically reviewed.Ultimately,this work delivers a comprehensive perspective on FPSCs from both optoelectronic and mechanical viewpoints,identifies key challenges,and outlines future research pathways toward the seamless integration of FPSCs into multifunctional,next-generation wearable systems.展开更多
Perovskite-silicon tandem solar cells,capable of combin-ing high power conversion efficiency(PCE)with cost-effective-ness,are widely regarded as a leading and pivotal direction for the next generation photovoltaic tec...Perovskite-silicon tandem solar cells,capable of combin-ing high power conversion efficiency(PCE)with cost-effective-ness,are widely regarded as a leading and pivotal direction for the next generation photovoltaic technology[1,2].In two-terminal tandem structure,a crystalline silicon(c-Si)bottom cell is directly series-connected with a wide-bandgap(1.65−1.7 eV)(WBG)perovskite top cell,thereby leverage the comple-mentary spectral absorption properties of perovskite and silicon and improve the overall sunlight harvesting efficiency:high-energy photons are absorbed by the perovskite layer,while transmitted low-energy photons are captured by the c-Si subcell[3].Advancements in WBG perovskite composition and additive engineering,interface modification strategies,and optical and structural optimization have significantly enhanced the optoelectronic performance of such solar cells[4−10].Since the initial demonstration of rigid per-ovskite/c-Si tandems in 2015[11],nearly a decade of intensive development has enabled this architecture to achieve certi-fied PCEs to 34.9%[12,13],exceeds the Shockley−Queisser efficiency limit for single-junction solar cells[14].展开更多
This study investigates the Maximum Power Point Tracking(MPPT)control method of offshore windphotovoltaic hybrid power generation system with offshore crane-assisted.A new algorithm of Global Fast Integral Sliding Mod...This study investigates the Maximum Power Point Tracking(MPPT)control method of offshore windphotovoltaic hybrid power generation system with offshore crane-assisted.A new algorithm of Global Fast Integral Sliding Mode Control(GFISMC)is proposed based on the tip speed ratio method and sliding mode control.The algorithm uses fast integral sliding mode surface and fuzzy fast switching control items to ensure that the offshore wind power generation system can track the maximum power point quickly and with low jitter.An offshore wind power generation system model is presented to verify the algorithm effect.An offshore off-grid wind-solar hybrid power generation systemis built in MATLAB/Simulink.Compared with other MPPT algorithms,this study has specific quantitative improvements in terms of convergence speed,tracking accuracy or computational efficiency.Finally,the improved algorithm is further analyzed and carried out by using Yuankuan Energy’s ModelingTech semi-physical simulation platform.The results verify the feasibility and effectiveness of the improved algorithm in the offshore wind-solar hybrid power generation system.展开更多
The fluorination strategy has been proven effective in significantly enhancing the photovoltaic performance of organic solar cells(OSCs) based on non-fused ring electron acceptors(NFREAs).However,research on the impac...The fluorination strategy has been proven effective in significantly enhancing the photovoltaic performance of organic solar cells(OSCs) based on non-fused ring electron acceptors(NFREAs).However,research on the impact of fluorination positions at side chains on NFREAs device performance remains scant.In this study,we introduce two isomeric NFREAs,designated as GA-2F-E and GA-2F,distinguished by their fluorination positions at the side chains.Both NFREAs share a thiophene[3,2-b]thiophene core,but their side chains differ:GA-2F-E features two(4-butylphenyl)-N-(4-fluorophenyl) amino groups,whereas GA-2F's side chains consist of bis(4-fluorophenyl)amino and bis(4-butylphenyl)amino groups attached to opposite sides of the core.To delve into the influence of fluorination positions on the optoelectronic properties,aggregation behavior,and overall efficiency of the acceptor molecules,a comprehensive investigation was conducted.The findings reveal that,despite similar photophysical properties and comparable absorption bandwidths,GA-2F-E,with fluorine atoms positioned on both sides of the molecular framework,demonstrates more compact π-π stacking,reduced bimolecular recombination,superior exciton transport,and a more balanced,higher mobility.As a result of these advantages,OSCs optimized with D18:GA-2F-E achieve a remarkable power conversion efficiency(PCE) of 16.45 %,surpassing the 15.83 %PCE of devices utilizing D18:GA-2F.This research underscores the potential of NFREAs in future applications and highlights the significance of fluorination positions in enhancing OSC performance,paving the way for the development of more efficient NFREAs.展开更多
A nonfused ring electron acceptor(NFREA),designated as TT-Ph-C6,has been synthesized with the aim of enhancing the power conversion efficiency(PCE)of organic solar cells(OSCs).By integrating asymmetric phenylalkylamin...A nonfused ring electron acceptor(NFREA),designated as TT-Ph-C6,has been synthesized with the aim of enhancing the power conversion efficiency(PCE)of organic solar cells(OSCs).By integrating asymmetric phenylalkylamino side groups,TT-Ph-C6 demonstrates excellent solubility and its crystal structure exhibits compact packing structures with a three-dimensional molecular stacking network.These structural attributes markedly promote exciton diffusion and charge carrier mobility,particularly advantageous for the fabrication of thick-film devices.TT-Ph-C6-based devices have attained a PCE of 18.01%at a film thickness of 100 nm,and even at a film thickness of 300 nm,the PCE remains at 14.64%,surpassing that of devices based on 2BTh-2F.These remarkable properties position TT-Ph-C6 as a highly promising NFREA material for boosting the efficiency of OSCs.展开更多
In this research highlight,recent significant advances with hot-assisted blade-coating or air knife-assisted blade-coating of different perovskite compositions with bandgaps ranging from 1.3 eV to 1.9 eV(i.e.widebandg...In this research highlight,recent significant advances with hot-assisted blade-coating or air knife-assisted blade-coating of different perovskite compositions with bandgaps ranging from 1.3 eV to 1.9 eV(i.e.widebandgap or small-bandgap perovskites with mixed cations and anions,2D/3D perovskites,Pb/Sn binary perovskites,and all-inorganic perovskites)for single-junction or tandem PSCs are discussed,with an emphasis on elucidating the distinct ink formulation engineering strategies,crystal growth mechanisms,crystallization kinetics,and optoelectronic properties of the different perovskite compositions.展开更多
Current high power load simulators are generally incapable of obtaining both high loading performance and high energy efficiency. Simulators with high energy efficiency are used to simulate static-state load, and thos...Current high power load simulators are generally incapable of obtaining both high loading performance and high energy efficiency. Simulators with high energy efficiency are used to simulate static-state load, and those with high dynamic performance typically have low energy efficiency. In this paper, the variants of secondary control（VSC） with power recovery are developed to solve this problem for loading hydraulic driving devices that operate under variable pressure, unlike classical secondary control（CSC） that operates in constant pressure network. Hydrostatic secondary control units are used as the loading components, by which the absorbed mechanical power from the tested device is converted into hydraulic power and then fed back into the tested system through 4 types of feedback passages（FPs）. The loading subsystem can operate in constant pressure network, controlled variable pressure network, or the same variable pressure network as that of the tested device by using different FPs. The 4 types of systems are defined, and their key techniques are analyzed, including work principle, simulating the work state of original tested device, static operation points, loading performance, energy efficiency, and control strategy, etc. The important technical merits of the 4 schemes are compared, and 3 of the schemes are selected, designed, simulated using AMESim and evaluated. The researching results show that the investigated systems can simulate the given loads effectively, realize the work conditions of the tested device, and furthermore attain a high power recovery efficiency that ranges from 0.54 to 0.85, even though the 3 schemes have different loading performances and energy efficiencies. This paper proposes several loading schemes that can achieve both high dynamic performance and high power recovery efficiency.展开更多
The rational design of polymer acceptors with strong and broad absorption is critical to improve photovoltaic performance.In this work,a new polymer acceptor PY9-T based on heptacyclic benzotriazole(Y9-C16)as a buildi...The rational design of polymer acceptors with strong and broad absorption is critical to improve photovoltaic performance.In this work,a new polymer acceptor PY9-T based on heptacyclic benzotriazole(Y9-C16)as a building block and thiophene unit as the linking unit was synthesized,which exhibited a low bandgap(1.37 eV)and a high extinction coefficient of the neat film(1.44×10^(5) cm^(−1)).When PY9-T was blended with the wide bandgap polymer donor PBDB-T,the all-polymer solar cells(APSCs)showed a high power conversion efficiency(PCE)of 10.45%with both high open circuit voltage of 0.881 V and short-circuit current density of 19.82 mA/cm^(2).In addition,APSCs based on PY9-T show good thermal stability,as evidenced by slight changes morphologies when annealed at 100℃.These results suggest that Y9-C16 provides a new building block to develop efficient and stable polymer acceptors.展开更多
The self-assembly process for compatible functional layers of devices is a simple,feasible,and energy-saving strategy.In mesoporous perovskite solar cells(PSCs),compact and scaffold TiO_(2) films generally function as...The self-assembly process for compatible functional layers of devices is a simple,feasible,and energy-saving strategy.In mesoporous perovskite solar cells(PSCs),compact and scaffold TiO_(2) films generally function as the hole-blocking and electron-transporting layers,respectively.However,both of these layers are usually generated through a high-temperature annealing process.Here,we deposited TiO_(2) compact films through a room-temperature self-assembly process as effective hole-blocking layers for PSCs.The thickness of TiO_(2) compact films can be easily controlled by the deposition time.Through the optimization of TiO_(2) compact films(80 nm),the power conversion efficiency(PCE)of mesoporous PSCs without and with hole conductor layers increases up to 10.66%and 17.95%,respectively.Notably,an all-low-temperature planar PSC with the self-assembled TiO_(2) layer exhibits a PCE of 16.41%.展开更多
Research on asymmetric A–D–A structured non-fullerene acceptors has lagged far behind the development of symmetric counterpart.In this contribution,by simply replacing one sulfur atom in indacenodithiophene unit wit...Research on asymmetric A–D–A structured non-fullerene acceptors has lagged far behind the development of symmetric counterpart.In this contribution,by simply replacing one sulfur atom in indacenodithiophene unit with a selenium atom,an asymmetric building block Se PT and a corresponding asymmetric non-fullerene acceptor Se PT-IN have been developed.Asymmetric Se PT-IN achieved a high efficiency of 10.20% in organic solar cells when blended with PBT1-C,much higher than that of symmetric TPT-IN counterpart(8.91%).Our results demonstrated an effective heteroatom substitution strategy to develop asymmetric A–D–A structured non-fullerene acceptors.展开更多
To overcome the problems encountered in predicting the endurance of electricpowered fixed-wing unmanned aerial vehicles(UAVs),which were stemmed from the dynamic changes in electric power system efficiency and battery...To overcome the problems encountered in predicting the endurance of electricpowered fixed-wing unmanned aerial vehicles(UAVs),which were stemmed from the dynamic changes in electric power system efficiency and battery discharge characteristics under different operating conditions,the required battery power model and battery discharge model were studied.The required battery power model was determined using an approximate model of electric power system efficiency based on wind tunnel testing and the self-adaptive penalty function.Furthermore,current correction and ambient temperature correction terms were proposed for the trained Kriging model representing the discharge characteristics under standard operation,and then the discharged capacity-terminal voltage model was established.Through numerical integration of this model with the required battery power model,the electric-powered fixed-wing UAV endurance prediction model was obtained.Laboratory tests indicated that the proposed endurance model could precisely calculate the battery discharge time and accurately describe the battery discharge process.The similarity of the theoretical and flight test results reflected the accuracy of the proposed endurance model as well as the importance of considering dynamic changes in power system efficiency in endurance calculations.The proposed endurance model meeting precision requirements can be used in practical engineering applications.展开更多
Valuable mineral resources are widely distributed throughout the seabed. autonomous underwater vehicles (AUVs) are preferable to remotely-operated vehicles (ROVs) when probing for such mineral resources as the extensi...Valuable mineral resources are widely distributed throughout the seabed. autonomous underwater vehicles (AUVs) are preferable to remotely-operated vehicles (ROVs) when probing for such mineral resources as the extensive exploration area makes it difficult to maintain contact with operators. AUVs depend on batteries, so their power consumption should be reduced to extend exploration time. Power for conventional marine instrument systems is incorporated in their waterproof sealing. External intermittent control of this power source until termination of exploration is challenging due to limitations imposed by the underwater environment. Thus, the AUV must have a power control system that can improve performance and maximize use of battery capacity. The authors developed such a power control system with a three-step algorithm. It automatically detects underwater operational states and can limit power, effectively decreasing power consumption by about 15%.展开更多
基金supported by the National Natural Science Foundation of China under Grant No.61071102
文摘Low power efficiency is a deficiency in traditional Orthogonal Frequency Division Multiplexing(OFDM)systems.To counter this problem,a new wireless transmission technology based on Zero-Padding Carrier Interferometry OFDM(ZP-CI/OFDM)is proposed.In a ZP-CI/OFDM system,transmission symbols are spread to all OFDM subcarriers via carrier interferometry codes.This reduces the Peak-to-Average Power Ratio(PAPR)that traditional OFDM suffers and also exploits frequency diversity gain.By zero-padding at the transmitter,advanced receiver technologies can be adopted for ZP-CI/OFDM so that frequency diversity gain can be further utilized and the power efficiency of the system is improved.
基金supported by the National Key Research and Development Program of China(No.2022YFB4200400)the National Natural Science Foundation of China(Nos.W2511056,52503289 and 52333005)+1 种基金Beijing Natural Science Foundation(No.Z230018)the Academic Excellence Foundation of BUAA for PhD Students。
文摘Carbazole derivatives with a single phosphonic acid(PA)group are widely used as monolayer interfaces in perovskites and organic solar cells(OSCs).However,their hydrophilic nature renders ITO electrodes hydrophobic,limiting further applications.In this study,a novel carbazole-based compound functionalized with two PA groups,denoted 2PACz-D1,was designed to create a dual hydrophilic interface.This configuration enables the formation of a bilayer hole-transporting layer(HTL).Specifically,one PA group anchors to the ITO electrode,while the other generates a secondary hydrophilic surface.This allows the subsequent deposition of hydrophilic PEDOT:PSS,forming a protective bilayer HTL that shields ITO from corrosive acidic polymers.The OSCs incorporating this bilayer HTL achieved a power conversion efficiency of 19.44%and exhibited improved thermal stability compared to devices with a single HTL.This work demonstrates the potential of bis-PA carbazole derivatives for tailoring the HTL surface properties,offering promising opportunities for various organic electronic devices.
文摘The use of alternative fuels to generate mechanical and thermal energy in engines is a promising and sought-after technological area with its own unique advantages and characteristics.Consequently,enhancing the technical,economic,and environmental efficiency of gas engines fueled by propane-butane mixture and syngas through optimized operating cycle parameters(including valve timing,ignition timing angle,fuel mixture composition,and compression ratio)is a pressing imperative for scientific and energy sectors.The aim of the study was to investigate and compare the performance of an engine with different compression ratios running on a propane-butane mixture and laboratory syngas.The research’s primary originality lies in its joint study of syngas production technology and the evaluation of the efficiency of a mini power plant fueled by the resulting gas and conventional gas.This article presents a description of the experimental setup,data on measuring instruments,technical characteristics of the mini-power plant,the process for obtaining laboratory syngas,the properties of the gaseous fuels used,and experimental methods.Data on air and fuel consumption,as well as engine efficiency at different compression ratios when running on a propane-butane mixture and syngas,were obtained and analyzed.Converting an engine from a propane-butane mixture to syngas results in a reduction in power of almost 30% and efficiency by 13%–33%.Increasing the compression ratio by 0.9 units causes a rise in maximum efficiency from 0.177 to 0.235 for an engine running on a propane-butane mixture and an increase in maximum efficiency from 0.136 to 0.161 for a syngas engine.It has been confirmed that the compression ratio significantly impacts the technical and economic performance of an engine running on gaseous fuel.The obtained results can be used to modernize existing engines for operation on alternative fuels(syngas)and to design new mini-power plants with promising technical,economic,and environmental characteristics.
基金supported by the National Natural Science Foundation of China(No.60906012)the Analog Devices Inc.(ADI)
文摘A low power high performance Delta-Sigma modulator for portable measurement applications is presented.To reduce power consumption while maintaining high performance,a fully feedforward architecture with a comprehensive system-level design is implemented.As a key building block,a novel power efficient current mirror operational transconductance amplifier(OTA)with a fast-settling less-error switched-capacitor common-mode feedback(SC CMFB)circuit is introduced,and the effects of both gain nonlinearity and 1/f noise of OTA are discussed.A new method to determine the voltage gain of an OTA is also proposed.The bottom terminal parasitic effect of poly-insulator-poly(PIP)capacitors is considered.About an extra 20%of capacitance is added to the total capacitance load.A power and area efficient resonator is adopted to realize a coefficient of 1/90 for 50%power and 75%area reduction compared with conventional designs.The chip is implemented in a low cost 0.35μm complementary metal oxide semiconductor(CMOS)process.The total power consumption is 20μW with a 1.5 V supply,and the measured dynamic range(DR)is 95 dB over a 1 kHz bandwidth.Experimental results show that a high figure-of-merit(FOM)is achieved for the designed modulator in comparison with those from the literature.
基金Project supported by the Ministry of Science & Technology of China(No.2008BAI55B07)the State Key Laboratory of ASIC and System,Fudan University,China(No.09MS009).
文摘The analysis and design of a semi-passive radio frequency identification（RFID） tag is presented.By studying the power transmission link of the backscatter RFID system and exploiting a power conversion efficiency model for a multi-stage AC-DC charge pump,the calculation method for semi-passive tag＇s read range is proposed.According to different read range limitation factors,an intuitive way to define the specifications of tag＇s power budget and backscatter modulation index is given.A test chip is implemented in SMIC 0.18μm standard CMOS technology under the guidance of theoretical analysis.The main building blocks are the threshold compensated charge pump and low power wake-up circuit using the power triggering wake-up mode.The proposed semi-passive tag is fully compatible to EPC C1G2 standard.It has a compact chip size of 0.54 mm^2,and is adaptable to batteries with a 1.2 to 2.4 V output voltage.
基金Supported by the National Natural Science Foundation of China under Grant No 11335003
文摘A polymeric nanopore membrane with selective ionic transport has been proposed as a potential device to convert the chemical potential energy in salinity gradients to electrical power. However, its energy conversion efficiency and power density are often limited due to the challenge in reliably controlling the size of the nanopores with the conventional chemical etching method. Here we report that without chemical etching, polyimide （PI） membranes irradiated with GeV heavy ions have negatively charged nanopores, showing nearly perfect selectivity for cations over anions, and they can generate electrical power from salinity gradients. We further demonstrate that the power generation efficiency of the PI membrane approaches the theoretical limit, and the maximum power density reaches 130m W/m2 with a modified etching method, outperforming the previous energy conversion device that was made of polymeric nanopore membranes.
基金partially supported by the National Natural Science Foundation of China(61571225,61271255,61232016,U1405254)the Open Foundation of Jiangsu Engineering Center of Network Monitoring(Nanjing University of Information Science and Technology)(Grant No.KJR1509)+2 种基金the PAPD fundthe CICAEET fundShenzhen Strategic Emerging Industry Development Funds(JSGG20150331160845693)
文摘Considering that perfect channel state information(CSI) is difficult to obtain in practice,energy efficiency(EE) for distributed antenna systems(DAS) based on imperfect CSI and antennas selection is investigated in Rayleigh fading channel.A novel EE that is defined as the average transmission rate divided by the total consumed power is introduced.In accordance with this definition,an adaptive power allocation(PA) scheme for DAS is proposed to maximize the EE under the maximum transmit power constraint.The solution of PA in the constrained EE optimization does exist and is unique.A practical iterative algorithm with Newton method is presented to obtain the solution of PA.The proposed scheme includes the one under perfect CSI as a special case,and it only needs large scale and statistical information.As a result,the scheme has low overhead and good robustness.The theoretical EE is also derived for performance evaluation,and simulation result shows the validity of the theoretical analysis.Moreover,EE can be enhanced by decreasing the estimation error and/or path loss exponents.
基金the National Natural Science Foundation of China(52303218 and 52303222)the China Postdoctoral Science Foundation(2022M720314)+1 种基金the Natural Science Foundation of Fujian Province(2023J01403)the Beijing Postdoctoral Science Foundation(2023-zz-101)for funding。
文摘With the continuous improvement of photovoltaic efficiency in the organic photovoltaic(OPV),interface engineering has emerged as a pivotal issue in their practical deployment.Currently,the robust crystallinity of small molecule electron transport layers(ETLs)and the poor film-forming abilities of conjugated polymer ETLs are a huge obstacle in this field.Herein,an innovative and efficient nonconjugated polymer ETL,namely PNDI-SO,which contains polar cationic segments for solubility and conjugated units for efficient charge transport in stable OPV cells,is reported.Endowed with suitable energy levels and excellent electron extraction capabilities,PNDI-SO-based OPV cells attain a power conversion efficiency(PCE)of 18.54%.Furthermore,compared with conventional OPV cells utilizing PFN-Br or PDINN,PNDI-SO substantially enhances long-term stability under continuous illumination,evidenced by a T80 lifetime(signifying retention of 80% of initial performance)exceeding 1250 h.Notably,through scanning electron microscope,we verified that PNDI-SO achieves a harmonious balance between film-forming ability and charge transport properties for ETL,enabling the blade-coating OPV based on PBDB-TF:BTP-eC9 to achieve a PCE of 17.47%.These results suggest the potential of PNDI-SO as a promising interface material for industrial printing applications in OPV fabrication.
基金supported by the Commercialization Promotion Agency for R&D Outcomes(COMPA)grant funded by the Korea government(Ministry of Science and ICT)(RS-2025-02311658)supported by the Ministry of Education of the Republic of Korea and the National Research Foundation of Korea(NRF-2023R1A2C2008017)Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(NRF-2020R1A6A1A03043435).
文摘Driven by rapid advancements in smart wearable technologies and perovskite photovoltaics,flexible perovskite solar cells(FPSCs)have emerged as highly promising autonomous power sources,poised to transform the next generation of mobile energy systems,portable electronics,and integrated wearable devices.For successful deployment in real-world scenarios,FPSCs must exhibit a combination of key attributes,including high power conversion efficiency,lightweight architecture,environmental robustness,and mechanical adaptability-encompassing flexibility,stretchability,and twistability.This review provides a detailed examination of the evolution,current state,and practical deployment of FPSCs,emphasizing their potential as efficient,portable energy solutions.It investigates advanced strategies for improving environmental resilience and mechanical recoverability,including the engineering of flexible substrates,deposition of high-quality perovskite films,and optimization of charge-selective interfaces.Additionally,it offers a systematic analysis of device design,fabrication protocols,scalable printing techniques,and standardized performance evaluation methods tailored for wearable FPSCs.Recent progress in enhancing the optoelectronic properties and mechanical durability of FPSCs is also critically reviewed.Ultimately,this work delivers a comprehensive perspective on FPSCs from both optoelectronic and mechanical viewpoints,identifies key challenges,and outlines future research pathways toward the seamless integration of FPSCs into multifunctional,next-generation wearable systems.
文摘Perovskite-silicon tandem solar cells,capable of combin-ing high power conversion efficiency(PCE)with cost-effective-ness,are widely regarded as a leading and pivotal direction for the next generation photovoltaic technology[1,2].In two-terminal tandem structure,a crystalline silicon(c-Si)bottom cell is directly series-connected with a wide-bandgap(1.65−1.7 eV)(WBG)perovskite top cell,thereby leverage the comple-mentary spectral absorption properties of perovskite and silicon and improve the overall sunlight harvesting efficiency:high-energy photons are absorbed by the perovskite layer,while transmitted low-energy photons are captured by the c-Si subcell[3].Advancements in WBG perovskite composition and additive engineering,interface modification strategies,and optical and structural optimization have significantly enhanced the optoelectronic performance of such solar cells[4−10].Since the initial demonstration of rigid per-ovskite/c-Si tandems in 2015[11],nearly a decade of intensive development has enabled this architecture to achieve certi-fied PCEs to 34.9%[12,13],exceeds the Shockley−Queisser efficiency limit for single-junction solar cells[14].
基金supported by the 2022 Sanya Science and Technology Innovation Project,China(No.2022KJCX03)the Sanya Science and Education Innovation Park,Wuhan University of Technology,China(Grant No.2022KF0028)the Hainan Provincial Joint Project of Sanya Yazhou Bay Science and Technology City,China(Grant No.2021JJLH0036).
文摘This study investigates the Maximum Power Point Tracking(MPPT)control method of offshore windphotovoltaic hybrid power generation system with offshore crane-assisted.A new algorithm of Global Fast Integral Sliding Mode Control(GFISMC)is proposed based on the tip speed ratio method and sliding mode control.The algorithm uses fast integral sliding mode surface and fuzzy fast switching control items to ensure that the offshore wind power generation system can track the maximum power point quickly and with low jitter.An offshore wind power generation system model is presented to verify the algorithm effect.An offshore off-grid wind-solar hybrid power generation systemis built in MATLAB/Simulink.Compared with other MPPT algorithms,this study has specific quantitative improvements in terms of convergence speed,tracking accuracy or computational efficiency.Finally,the improved algorithm is further analyzed and carried out by using Yuankuan Energy’s ModelingTech semi-physical simulation platform.The results verify the feasibility and effectiveness of the improved algorithm in the offshore wind-solar hybrid power generation system.
基金financially supported by the National Natural Science Foundation of China (Nos.22375024,21975031,51933001,and 21734009)。
文摘The fluorination strategy has been proven effective in significantly enhancing the photovoltaic performance of organic solar cells(OSCs) based on non-fused ring electron acceptors(NFREAs).However,research on the impact of fluorination positions at side chains on NFREAs device performance remains scant.In this study,we introduce two isomeric NFREAs,designated as GA-2F-E and GA-2F,distinguished by their fluorination positions at the side chains.Both NFREAs share a thiophene[3,2-b]thiophene core,but their side chains differ:GA-2F-E features two(4-butylphenyl)-N-(4-fluorophenyl) amino groups,whereas GA-2F's side chains consist of bis(4-fluorophenyl)amino and bis(4-butylphenyl)amino groups attached to opposite sides of the core.To delve into the influence of fluorination positions on the optoelectronic properties,aggregation behavior,and overall efficiency of the acceptor molecules,a comprehensive investigation was conducted.The findings reveal that,despite similar photophysical properties and comparable absorption bandwidths,GA-2F-E,with fluorine atoms positioned on both sides of the molecular framework,demonstrates more compact π-π stacking,reduced bimolecular recombination,superior exciton transport,and a more balanced,higher mobility.As a result of these advantages,OSCs optimized with D18:GA-2F-E achieve a remarkable power conversion efficiency(PCE) of 16.45 %,surpassing the 15.83 %PCE of devices utilizing D18:GA-2F.This research underscores the potential of NFREAs in future applications and highlights the significance of fluorination positions in enhancing OSC performance,paving the way for the development of more efficient NFREAs.
基金Financial support from the National Natural Science Foundation of China(22375024,21975031,21734009,51933001,22109080,and 52173174)the Natural Science Foundation of Shandong Province(No.ZR2022YQ45)+2 种基金the Taishan Scholars Program(Nos.tstp20221121 and tsqnz20221134)The Beijing Natural Science Foundation(No.2244073)supported by State Key Laboratory of Bio-Fibers and Eco-Textiles(Qingdao University)(RZ2200002821)is acknowledged.
文摘A nonfused ring electron acceptor(NFREA),designated as TT-Ph-C6,has been synthesized with the aim of enhancing the power conversion efficiency(PCE)of organic solar cells(OSCs).By integrating asymmetric phenylalkylamino side groups,TT-Ph-C6 demonstrates excellent solubility and its crystal structure exhibits compact packing structures with a three-dimensional molecular stacking network.These structural attributes markedly promote exciton diffusion and charge carrier mobility,particularly advantageous for the fabrication of thick-film devices.TT-Ph-C6-based devices have attained a PCE of 18.01%at a film thickness of 100 nm,and even at a film thickness of 300 nm,the PCE remains at 14.64%,surpassing that of devices based on 2BTh-2F.These remarkable properties position TT-Ph-C6 as a highly promising NFREA material for boosting the efficiency of OSCs.
基金the financial supports from the National Key R&D Program of China(2019YFB1503200)the GDUPS(2016)+4 种基金the NSF of Guangdong Province(2019B1515120050)the Fundamental Research Funds for the Central Universities(19lgjc07)the financial support from the Guangdong Basic and Applied Basic Research Foundation(2019A1515110770)National Key Research and Development Program of China(2017YFA0206600)National Natural Science Foundation of China(51773045,21772030,51922032,21961160720)for financial support
文摘In this research highlight,recent significant advances with hot-assisted blade-coating or air knife-assisted blade-coating of different perovskite compositions with bandgaps ranging from 1.3 eV to 1.9 eV(i.e.widebandgap or small-bandgap perovskites with mixed cations and anions,2D/3D perovskites,Pb/Sn binary perovskites,and all-inorganic perovskites)for single-junction or tandem PSCs are discussed,with an emphasis on elucidating the distinct ink formulation engineering strategies,crystal growth mechanisms,crystallization kinetics,and optoelectronic properties of the different perovskite compositions.
文摘Current high power load simulators are generally incapable of obtaining both high loading performance and high energy efficiency. Simulators with high energy efficiency are used to simulate static-state load, and those with high dynamic performance typically have low energy efficiency. In this paper, the variants of secondary control（VSC） with power recovery are developed to solve this problem for loading hydraulic driving devices that operate under variable pressure, unlike classical secondary control（CSC） that operates in constant pressure network. Hydrostatic secondary control units are used as the loading components, by which the absorbed mechanical power from the tested device is converted into hydraulic power and then fed back into the tested system through 4 types of feedback passages（FPs）. The loading subsystem can operate in constant pressure network, controlled variable pressure network, or the same variable pressure network as that of the tested device by using different FPs. The 4 types of systems are defined, and their key techniques are analyzed, including work principle, simulating the work state of original tested device, static operation points, loading performance, energy efficiency, and control strategy, etc. The important technical merits of the 4 schemes are compared, and 3 of the schemes are selected, designed, simulated using AMESim and evaluated. The researching results show that the investigated systems can simulate the given loads effectively, realize the work conditions of the tested device, and furthermore attain a high power recovery efficiency that ranges from 0.54 to 0.85, even though the 3 schemes have different loading performances and energy efficiencies. This paper proposes several loading schemes that can achieve both high dynamic performance and high power recovery efficiency.
基金Project(21875286)supported by the National Natural Science Foundation of China。
文摘The rational design of polymer acceptors with strong and broad absorption is critical to improve photovoltaic performance.In this work,a new polymer acceptor PY9-T based on heptacyclic benzotriazole(Y9-C16)as a building block and thiophene unit as the linking unit was synthesized,which exhibited a low bandgap(1.37 eV)and a high extinction coefficient of the neat film(1.44×10^(5) cm^(−1)).When PY9-T was blended with the wide bandgap polymer donor PBDB-T,the all-polymer solar cells(APSCs)showed a high power conversion efficiency(PCE)of 10.45%with both high open circuit voltage of 0.881 V and short-circuit current density of 19.82 mA/cm^(2).In addition,APSCs based on PY9-T show good thermal stability,as evidenced by slight changes morphologies when annealed at 100℃.These results suggest that Y9-C16 provides a new building block to develop efficient and stable polymer acceptors.
基金financially supported by the National Natural Science Foundation of China(No.52172205)。
文摘The self-assembly process for compatible functional layers of devices is a simple,feasible,and energy-saving strategy.In mesoporous perovskite solar cells(PSCs),compact and scaffold TiO_(2) films generally function as the hole-blocking and electron-transporting layers,respectively.However,both of these layers are usually generated through a high-temperature annealing process.Here,we deposited TiO_(2) compact films through a room-temperature self-assembly process as effective hole-blocking layers for PSCs.The thickness of TiO_(2) compact films can be easily controlled by the deposition time.Through the optimization of TiO_(2) compact films(80 nm),the power conversion efficiency(PCE)of mesoporous PSCs without and with hole conductor layers increases up to 10.66%and 17.95%,respectively.Notably,an all-low-temperature planar PSC with the self-assembled TiO_(2) layer exhibits a PCE of 16.41%.
基金financially supported by the National Natural Science Foundation of China (NSFC) (Nos. 21674007 and 21734001)the financial support from National Research Foundation (NRF) of Korea (2012M3A6A7055540 and 2015M1A2A2057506)
文摘Research on asymmetric A–D–A structured non-fullerene acceptors has lagged far behind the development of symmetric counterpart.In this contribution,by simply replacing one sulfur atom in indacenodithiophene unit with a selenium atom,an asymmetric building block Se PT and a corresponding asymmetric non-fullerene acceptor Se PT-IN have been developed.Asymmetric Se PT-IN achieved a high efficiency of 10.20% in organic solar cells when blended with PBT1-C,much higher than that of symmetric TPT-IN counterpart(8.91%).Our results demonstrated an effective heteroatom substitution strategy to develop asymmetric A–D–A structured non-fullerene acceptors.
文摘To overcome the problems encountered in predicting the endurance of electricpowered fixed-wing unmanned aerial vehicles(UAVs),which were stemmed from the dynamic changes in electric power system efficiency and battery discharge characteristics under different operating conditions,the required battery power model and battery discharge model were studied.The required battery power model was determined using an approximate model of electric power system efficiency based on wind tunnel testing and the self-adaptive penalty function.Furthermore,current correction and ambient temperature correction terms were proposed for the trained Kriging model representing the discharge characteristics under standard operation,and then the discharged capacity-terminal voltage model was established.Through numerical integration of this model with the required battery power model,the electric-powered fixed-wing UAV endurance prediction model was obtained.Laboratory tests indicated that the proposed endurance model could precisely calculate the battery discharge time and accurately describe the battery discharge process.The similarity of the theoretical and flight test results reflected the accuracy of the proposed endurance model as well as the importance of considering dynamic changes in power system efficiency in endurance calculations.The proposed endurance model meeting precision requirements can be used in practical engineering applications.
文摘Valuable mineral resources are widely distributed throughout the seabed. autonomous underwater vehicles (AUVs) are preferable to remotely-operated vehicles (ROVs) when probing for such mineral resources as the extensive exploration area makes it difficult to maintain contact with operators. AUVs depend on batteries, so their power consumption should be reduced to extend exploration time. Power for conventional marine instrument systems is incorporated in their waterproof sealing. External intermittent control of this power source until termination of exploration is challenging due to limitations imposed by the underwater environment. Thus, the AUV must have a power control system that can improve performance and maximize use of battery capacity. The authors developed such a power control system with a three-step algorithm. It automatically detects underwater operational states and can limit power, effectively decreasing power consumption by about 15%.
