The oxidization resistance of the Ni76Cr19A1Ti alloy was studied by a static oxidization experiment at 600-800℃. The results show that the oxidation behavior of the alloy can be explained by a kinetic equation： （△...The oxidization resistance of the Ni76Cr19A1Ti alloy was studied by a static oxidization experiment at 600-800℃. The results show that the oxidation behavior of the alloy can be explained by a kinetic equation： （△m/S）2 = Kpt ＋ C, where Kp is a kinetic constant of the nickel-base alloy. The higher the experimental temperature, the higher the value of Kp. It is discovered that the microstructure of the oxide scales is compact and the thickness of it is less than 10 μm The oxidization of the alloy is in the first grade. It is also found that the oxide scales are mainly composed of Cr2O3 and TiO2. Chrome and titanium react more easily with oxygen at temperatures under the operating mode.展开更多
Position sensitive device(PSD)sensor is a vital optical element that is mainly used in tracking systems for visible light communication(VLC).Recently,a new reconfigurable PSD architecture emerged.The proposed architec...Position sensitive device(PSD)sensor is a vital optical element that is mainly used in tracking systems for visible light communication(VLC).Recently,a new reconfigurable PSD architecture emerged.The proposed architecture makes the PSD perform more functions by modifying its architecture.As the PSD is mainly formed of an array of photodiodes.The primary concept involves employing transistors to alternate between the operating modes of the photodiodes(photoconductive and photovoltaic).Additionally,alternating among output pins can be done based on the required function.This paper presents the mathematical modeling and simulation of a reconfigurable-multifunctional optical sensor which can perform energy harvesting and data acquisition,as well as positioning,which is not available in the traditional PSDs.Simulation using the MATLAB software tool was achieved to demonstrate the modeling.The simulation results confirmed the validity of the mathematical modeling and proved that the modified sensor architecture,as depicted by the equations,accurately describes its behavior.The proposed sensor is expected to extend the battery's lifecycle,reduce its physical size,and increase the integration and functionality of the system.The presented sensor might be used in free space optical(FSO)communication like cube satellites or even in underwater wireless optical communication(UWOC).展开更多
To enhance energy interaction among low-voltage stations(LVSs)and reduce the line loss of the distribution network,a novel operation mode of the micro-pumped storage system(mPSS)has been proposed based on the common r...To enhance energy interaction among low-voltage stations(LVSs)and reduce the line loss of the distribution network,a novel operation mode of the micro-pumped storage system(mPSS)has been proposed based on the common reservoir.First,some operation modes of mPSS are analyzed,which include the separated reservoir mode(SRM)and common reservoir mode(CRM).Then,based on the SRM,and CRM,an energy mutual assistance control model between LVSs has been built to optimize energy loss.Finally,in the simulation,compared to the model without pumped storage in the LVS,the SRMand CLRMcan decrease the total energy loss by 294.377 and 432.578 kWh,respectively.The configuration of mPSS can improve the utilization rate of the new energy source generation system,and relieve the pressure of transformer capacity in the LVS.Compared with the SRM,the proposed CRM has reduced the total energy loss by 138.201 kWh,increased the new energy consumption by 161.642 kWh,and decreased the line loss by 7.271 kWh.With the efficiency of the mPSS improving,the total energy loss reduction of CRM will be 3.5 times that of SRM.Further,the CRMcan significantly reduce the reservoir capacity construction of mPSS and ismore suitable for scenarios where the capacity configuration of mPSS is limited.展开更多
Extracting typical operational scenarios is essential for making flexible decisions in the dispatch of a new power system.A novel deep time series aggregation scheme(DTSAs)is proposed to generate typical operational s...Extracting typical operational scenarios is essential for making flexible decisions in the dispatch of a new power system.A novel deep time series aggregation scheme(DTSAs)is proposed to generate typical operational scenarios,considering the large amount of historical operational snapshot data.Specifically,DTSAs analyse the intrinsic mechanisms of different scheduling operational scenario switching to mathematically represent typical operational scenarios.A Gramian angular summation field-based operational scenario image encoder was designed to convert operational scenario sequences into highdimensional spaces.This enables DTSAs to fully capture the spatiotemporal characteristics of new power systems using deep feature iterative aggregation models.The encoder also facilitates the generation of typical operational scenarios that conform to historical data distributions while ensuring the integrity of grid operational snapshots.Case studies demonstrate that the proposed method extracted new fine-grained power system dispatch schemes and outperformed the latest high-dimensional feature-screening methods.In addition,experiments with different new energy access ratios were conducted to verify the robustness of the proposed method.DTSAs enable dispatchers to master the operation experience of the power system in advance,and actively respond to the dynamic changes of the operation scenarios under the high access rate of new energy.展开更多
This study proposes a novel combined primary and secondary control approach for direct current microgrids,specifi-cally in islanded mode.In primary control,this approach establishes an appropriate load power sharing b...This study proposes a novel combined primary and secondary control approach for direct current microgrids,specifi-cally in islanded mode.In primary control,this approach establishes an appropriate load power sharing between the distributed energy resources based on their rated power.Simultaneously,it considers the load voltage deviation and provides satisfactory voltage regulation in the secondary control loop.The proposed primary control is based on an efficient droop mechanism that only deploys the local variable measurements,so as to overcome the side effects caused by communication delays.In the case of secondary control,two different methods are devised.In the first,low bandwidth communication links are used to establish the minimum required data transfer between the converters.The effect of communication delay is further explored.The second method excludes any communication link and only uses local variables.Accordingly,a self-sufficient control loop is devised without any communication require-ment.The proposed control notions are investigated in MATLAB/Simulink platform to highlight system performance.The results demonstrate that both proposed approaches can effectively compensate for the voltage deviation due to the primary control task.Detailed comparisons of the two methods are also provided.展开更多
Cold thermal energy storage is an active method for reducing the peak electrical demand and electricity consumption of air con-ditioners.This paper investigates two different cases:partial operating mode-load levellin...Cold thermal energy storage is an active method for reducing the peak electrical demand and electricity consumption of air con-ditioners.This paper investigates two different cases:partial operating mode-load levelling(POM-LL)and demand-limiting mode(DLM).4E(energy,exergy,economic,environment)analyses along with a multi-objective optimization process based on a genetic algorithm is applied to determine optimal design values.Exergy efficiency,total annual cost and payback-period time are considered as objective functions in this study.The results have shown that POM and DLM decreased the electricity consumption by 10.36%and 11.29%,respectively,resulting in raising the annual costs by 11.08%and 11.42%.Also,their annual payback periods were 4.36 and 4.18 years each.In addition,using off-peak hours instead of on-peak hours for electricity consumption and reducing electricity consump-tion are the two main ways of decreasing CO_(2) emissions during electricity generation.Therefore,the CO_(2) emissions through POM and DLM are 13.31%and 13.72%less than those of conventional systems,respectively.展开更多
We report on the design and fabrication of λ-7.2μm distributed feedback quantum cascade lasers lot very high temperature cw operation and low electrical power consumption. The cw operation is reported above 90℃. Fo...We report on the design and fabrication of λ-7.2μm distributed feedback quantum cascade lasers lot very high temperature cw operation and low electrical power consumption. The cw operation is reported above 90℃. For a 2-mm-long and 10-μm-wide laser coated with high-reflectivity on the rear facet, more than 170mW of output power is obtained at 20℃ with a threshold power consumption of 2.4 W, corresponding to 30mW with a threshold power consumption of 3.9 W at 90℃. Robust single-mode emission with a side-mode suppression ratio above 25 dB is continuously tunable by the heat sink temperature or injection current.展开更多
Light-framed timber structure(LTS)buildings have been highly valued in recent years due to their low-carbon characteristics.However,the applicability of the building envelope is closely related to indoor and outdoor c...Light-framed timber structure(LTS)buildings have been highly valued in recent years due to their low-carbon characteristics.However,the applicability of the building envelope is closely related to indoor and outdoor conditions.The hot summer and cold winter(HSCW)climate zone in China has high humidity and great temperature variation throughout the year,resulting in distinct outdoor environments in different seasons.The indoor environment is greatly affected by energy-consumption patterns and window-opening habits,which largely depend upon the regulation operations of occupants.All these interrelated factors lead to extremely complex boundary conditions on each side of the building envelope.Whether the structures of LTS buildings are applicable in this climate zone,therefore,needs to be carefully considered.In this study,two LTS buildings with different envelopes were established in Haining,China,situated in the HSCW climate zone,and selected as the study objects.Different operation modes were adopted to create a variety of indoor environments.Under each condition,the processes of heat and moisture transfer within the building envelopes and the indoor environment were monitored and compared.The comparison indicated that the building envelope with high moisture storage and insulation ability maintained a relatively stable indoor environment,especially when the environment changed abruptly.Conversely,if the outdoor environment was equable(e.g.,relative humidity within the range of 30%–60%)or intermittent energy consumption modes were adopted,the building envelope with a low thermal inertia index and weak moisture-buffering ability performed better because it enabled a faster response of the indoor environment to air conditioning.Moreover,a high risk of moisture accumulation between the thermal insulation layer and other materials with a large water vapour transfer resistance factor was also identified,suggesting a higher requirement for the vapour insulation of the envelopes of LTS buildings.展开更多
To guide the illuminating design to improve the on-state performances of gallium arsenide(GaAs)photoconductive semiconductor switch(PCSS),the effect of spot size on the operation mode of GaAsPCSS based on a semi-insul...To guide the illuminating design to improve the on-state performances of gallium arsenide(GaAs)photoconductive semiconductor switch(PCSS),the effect of spot size on the operation mode of GaAsPCSS based on a semi-insulating wafer with a thickness of 1 mm,triggered by a 1064-nm extrinsic laser beam with the rectangular spot,has been investigated experimentally.It is found that the variation of the spot size in length and width can act on the different parts of the output waveform integrating the characteristics of the linear and nonlinear modes,and then significantly boosts the PCSS toward different operation modes.On this basis,a two-channel model containing the active and passive parts is introduced to interpret the relevant influencing mechanisms.Results indicate that the increased spot length can peak the amplitude of static domains in the active part to enhance the development of the nonlinear switching,while the extended spot width can change the distribution of photogenerated carriers on both parts to facilitate the linear switching and weaken the nonlinear switching,which have been proved by comparing the domain evolutions under different spot sizes.展开更多
The bipolar ionic liquid thruster employs ionic liquid as a propellant to discharge positively and negatively charged high-energy particles under an alternating current(AC)power source,effectively suppressing electroc...The bipolar ionic liquid thruster employs ionic liquid as a propellant to discharge positively and negatively charged high-energy particles under an alternating current(AC)power source,effectively suppressing electrochemical reaction and ensuring charge neutrality.Determining an optimal AC supply power source frequency is critical for sustained stable thruster operation.This study focuses on the emission characteristics of the ionic liquid thruster under varied AC conditions.The AC power supply was set within the frequency range of 0.5-64 Hz,with eight specific frequency conditions selected for experimentation.The experimental results indicate that the thruster operates steadily within a voltage range of±1470 to±1920 V,with corresponding positive polarity current ranging from 0.41 to 4.91μA and negative polarity current ranging from−0.49 to−4.10μA.During voltage polarity switching,an emission delay occurs,manifested as a prominent peak signal caused by circuit capacitance characteristics and a minor peak signal resulting from liquid droplets.Extended emission test was conducted at 16 Hz,demonstrating approximately 1 h and 50 min of consistent emission before intermittent discharge.These findings underscore the favorable impact of AC conditions within the 8-16 Hz range on the self-neutralization capability of the ionic liquid thruster.展开更多
As the Chinese government proposes ambitious plans to promote low-carbon transition,energy storage will play a pivotal role in China’s future power system.However,due to the lack of a mature electricity market enviro...As the Chinese government proposes ambitious plans to promote low-carbon transition,energy storage will play a pivotal role in China’s future power system.However,due to the lack of a mature electricity market environment and corresponding mechanisms,current energy storage in China faces problems such as unclear operational models,insufficient cost recovery mechanisms,and a single investment entity,making it difficult to support the rapid development of the energy storage industry.In contrast,European and American countries have already embarked on certain practices in energy storage operation models.Through exploration of key issues such as investment entities,market participation forms,and cost recovery channels in both front and back markets,a wealth of mature experiences has been accumulated.Therefore,this paper first summarizes the existing practices of energy storage operation models in North America,Europe,and Australia’s electricity markets separately from front and back markets,finding that perfect market mechanisms and reasonable subsidy policies are among the main drivers for promoting the rapid development of energy storage markets.Subsequently,combined with the actual development of China’s electricity market,it explores three key issues affecting the construction of costsharing mechanisms for energy storage under market conditions:Market participation forms,investment and operation modes,and cost recovery mechanisms.Finally,in line with the development expectations of China’s future electricitymarket,suggestions are proposed fromfour aspects:Market environment construction,electricity price formation mechanism,cost sharing path,and policy subsidy mechanism,to promote the healthy and rapid development of China’s energy storage industry.展开更多
Power flow adjustment is a sequential decision problem.The operator makes decisions to ensure that the power flow meets the system's operational constraints,thereby obtaining a typical operating mode power flow.Ho...Power flow adjustment is a sequential decision problem.The operator makes decisions to ensure that the power flow meets the system's operational constraints,thereby obtaining a typical operating mode power flow.However,this decision-making method relies heavily on human experience,which is inefficient when the system is complex.In addition,the results given by the current evaluation system are difficult to directly guide the intelligent power flow adjustment.In order to improve the efficiency and intelligence of power flow adjustment,this paper proposes a power flow adjustment method based on deep reinforcement learning.Combining deep reinforcement learning theory with traditional power system operation mode analysis,the concept of region mapping is proposed to describe the adjustment process,so as to analyze the process of power flow calculation and manual adjustment.Considering the characteristics of power flow adjustment,a Markov decision process model suitable for power flow adjustment is constructed.On this basis,a double Q network learning method suitable for power flow adjustment is proposed.This method can adjust the power flow according to the set adjustment route,thus improving the intelligent level of power flow adjustment.The method in this paper is tested on China Electric Power Research Institute(CEPRI)test system.展开更多
There are multiple operating modes in the real industrial process, and the collected data follow the complex multimodal distribution, so most traditional process monitoring methods are no longer applicable because the...There are multiple operating modes in the real industrial process, and the collected data follow the complex multimodal distribution, so most traditional process monitoring methods are no longer applicable because their presumptions are that sampled-data should obey the single Gaussian distribution or non-Gaussian distribution. In order to solve these problems, a novel weighted local standardization(WLS) strategy is proposed to standardize the multimodal data, which can eliminate the multi-mode characteristics of the collected data, and normalize them into unimodal data distribution. After detailed analysis of the raised data preprocessing strategy, a new algorithm using WLS strategy with support vector data description(SVDD) is put forward to apply for multi-mode monitoring process. Unlike the strategy of building multiple local models, the developed method only contains a model without the prior knowledge of multi-mode process. To demonstrate the proposed method's validity, it is applied to a numerical example and a Tennessee Eastman(TE) process. Finally, the simulation results show that the WLS strategy is very effective to standardize multimodal data, and the WLS-SVDD monitoring method has great advantages over the traditional SVDD and PCA combined with a local standardization strategy(LNS-PCA) in multi-mode process monitoring.展开更多
With the gradually popularization of replacing coal tobacco leaf flue-curing technology with biomass fuel, the operation of raw materials collection and transportation links faces many problems. In this paper, the exi...With the gradually popularization of replacing coal tobacco leaf flue-curing technology with biomass fuel, the operation of raw materials collection and transportation links faces many problems. In this paper, the existing problems in view of biomass fuel operation dominated by tobacco straw in current tobacco leaf flue-curing were analyzed, and the 3 kinds of fuel operation modes （＂contracting processing mode, displacement mode and commercialization mode＂） were put forward, each of which was also briefly analyzed, with the aim to expand the way of thinking about biomass raw materials processing by cooperative organization.展开更多
With the rise of remote collaboration,the demand for advanced storage and collaboration tools has rapidly increased.However,traditional collaboration tools primarily rely on access control,leaving data stored on cloud...With the rise of remote collaboration,the demand for advanced storage and collaboration tools has rapidly increased.However,traditional collaboration tools primarily rely on access control,leaving data stored on cloud servers vulnerable due to insufficient encryption.This paper introduces a novel mechanism that encrypts data in‘bundle’units,designed to meet the dual requirements of efficiency and security for frequently updated collaborative data.Each bundle includes updated information,allowing only the updated portions to be reencrypted when changes occur.The encryption method proposed in this paper addresses the inefficiencies of traditional encryption modes,such as Cipher Block Chaining(CBC)and Counter(CTR),which require decrypting and re-encrypting the entire dataset whenever updates occur.The proposed method leverages update-specific information embedded within data bundles and metadata that maps the relationship between these bundles and the plaintext data.By utilizing this information,the method accurately identifies the modified portions and applies algorithms to selectively re-encrypt only those sections.This approach significantly enhances the efficiency of data updates while maintaining high performance,particularly in large-scale data environments.To validate this approach,we conducted experiments measuring execution time as both the size of the modified data and the total dataset size varied.Results show that the proposed method significantly outperforms CBC and CTR modes in execution speed,with greater performance gains as data size increases.Additionally,our security evaluation confirms that this method provides robust protection against both passive and active attacks.展开更多
An integrated dynamic model of China＇s deep ocean mining system is developed and the fast simulation analysis of its longitudinal reciprocating motion operation processes is achieved. The seafloor tracked miner is bu...An integrated dynamic model of China＇s deep ocean mining system is developed and the fast simulation analysis of its longitudinal reciprocating motion operation processes is achieved. The seafloor tracked miner is built as a three-dimensional single-body model with six-degree-of-freedom. The track-terrain interaction is modeled by partitioning the track-terrain interface into a certain number of mesh elements with three mutually perpendicular forces, including the normal force, the longitudinal shear force and the lateral shear force, acting on the center point of each mesh element. The hydrodynamic force of the miner is considered and applied. By considering the operational safety and collection efficiency, two new mining paths for the miner on the seafloor are proposed, which can be simulated with the established single-body dynamic model of the miner. The pipeline subsystem is built as a three-dimensional multi-body discrete element model, which is divided into rigid elements linked by flexible connectors. The flexible connector without mass is represented by six spring-damper elements. The external hydrodynamic forces of the ocean current from the longitudinal and lateral directions are both considered and modeled based on the Morison formula and applied to the mass center of each corresponding discrete rigid element. The mining ship is simplified and represented by a general kinematic point, whose heave motion induced by the ocean waves and the longitudinal and lateral towing motions are considered and applied. By integrating the single-body dynamic model of the miner and the multi-body discrete element dynamic model of the pipeline, and defining the kinematic equations of the mining ship, the integrated dynamic model of the total deep ocean mining system is formed. The longitudinal reciprocating motion operation modes of the total mining system, which combine the active straight-line and turning motions of the miner and the ship, and the passive towed motions of the pipeline, are proposed and simulated with the developed 3D dynamic model. Some critical simulation results are obtained and analyzed, such as the motion trajectories of key subsystems, the velocities of the buoyancy modules and the interaction forces between subsystems, which in a way can provide important theoretical basis and useful technical reference for the practical deep ocean mining system analysis, operation and control.展开更多
The discharge operation regime of pulse modulated atmospheric radio frequency （RF） glow discharge in helium is investigated on the duty cycle and frequency of modulation pulses. The characteristics of radio frequenc...The discharge operation regime of pulse modulated atmospheric radio frequency （RF） glow discharge in helium is investigated on the duty cycle and frequency of modulation pulses. The characteristics of radio frequency discharge burst in terms of breakdown voltage, alpha（s）- gamma（γ） mode transition voltage and current are demonstrated by the discharge current voltage characteristics. The minimum breakdown voltage of RF discharge burst was obtained at the duty cycle of 20% and frequency of 400 kHz, respectively. The α-γ mode transition of RF discharge burst occurs at higher voltage and current by reducing the duty cycle and elevating the modulation frequency before the RF discharge burst evolving into the ignition phase, in which the RF discharge burst can operate stably in the γ mode. It proposes that the intensity and stability of RF discharge burst can be improved by manipulating the duty cycle and modulation frequency in pulse modulated atmospheric RF glow discharge.展开更多
Virtual supply chain, as a modern collaborative mode of enterprises, is important to decrease the cost and improve the efficiency and the quality of supply chains, and to satisfy customers. Based on the analysis of th...Virtual supply chain, as a modern collaborative mode of enterprises, is important to decrease the cost and improve the efficiency and the quality of supply chains, and to satisfy customers. Based on the analysis of the conception and characteristics of the virtual supply chain, the architecture of virtual supply chain is built, and corresponding objects, tasks, information and technologies are described. Three operation modes-Order-driven, manufacturer-centered, and retailer-centered are researched. As a case, virtual supply chain is applied in the electronic commerce and networked customization system of ceramic products.展开更多
The effects of feed gas flow rate and operating current on the electrical characteristics and dynamic behavior of a rotating gliding arc （RGA） plasma codriven by a magnetic field and tangential flow were investigate...The effects of feed gas flow rate and operating current on the electrical characteristics and dynamic behavior of a rotating gliding arc （RGA） plasma codriven by a magnetic field and tangential flow were investigated.The operating current has been shown to significantly affect the time-resolved voltage waveforms of the discharge,particularly at flow rate =21 min^-1.When the current was lower than 140 mA,sinusoidal waveforms with regular variation periods of 13.5-17.0 ms can be observed （flow rate =21 min^-1）.The restrike mode characterized by serial sudden drops of voltage appeared under all studied conditions.Increasing the flow rate from 8 to 121 min^-1 （at the same current） led to a shift of arc rotation mode which would then result in a significant drop of discharge voltage （around 120-200 V）.For a given flow rate,the reduction of current resulted in a nearly linear increase of voltage.展开更多
文摘The oxidization resistance of the Ni76Cr19A1Ti alloy was studied by a static oxidization experiment at 600-800℃. The results show that the oxidation behavior of the alloy can be explained by a kinetic equation： （△m/S）2 = Kpt ＋ C, where Kp is a kinetic constant of the nickel-base alloy. The higher the experimental temperature, the higher the value of Kp. It is discovered that the microstructure of the oxide scales is compact and the thickness of it is less than 10 μm The oxidization of the alloy is in the first grade. It is also found that the oxide scales are mainly composed of Cr2O3 and TiO2. Chrome and titanium react more easily with oxygen at temperatures under the operating mode.
文摘Position sensitive device(PSD)sensor is a vital optical element that is mainly used in tracking systems for visible light communication(VLC).Recently,a new reconfigurable PSD architecture emerged.The proposed architecture makes the PSD perform more functions by modifying its architecture.As the PSD is mainly formed of an array of photodiodes.The primary concept involves employing transistors to alternate between the operating modes of the photodiodes(photoconductive and photovoltaic).Additionally,alternating among output pins can be done based on the required function.This paper presents the mathematical modeling and simulation of a reconfigurable-multifunctional optical sensor which can perform energy harvesting and data acquisition,as well as positioning,which is not available in the traditional PSDs.Simulation using the MATLAB software tool was achieved to demonstrate the modeling.The simulation results confirmed the validity of the mathematical modeling and proved that the modified sensor architecture,as depicted by the equations,accurately describes its behavior.The proposed sensor is expected to extend the battery's lifecycle,reduce its physical size,and increase the integration and functionality of the system.The presented sensor might be used in free space optical(FSO)communication like cube satellites or even in underwater wireless optical communication(UWOC).
基金sponsored by the State Grid Corporation of China Technology Project(Research on Key Technologies and Equipment Development of Micro Pumped Storage for Distributed New Energy Consumption in Distribution Networks,5400-202324196A-1-1-ZN).
文摘To enhance energy interaction among low-voltage stations(LVSs)and reduce the line loss of the distribution network,a novel operation mode of the micro-pumped storage system(mPSS)has been proposed based on the common reservoir.First,some operation modes of mPSS are analyzed,which include the separated reservoir mode(SRM)and common reservoir mode(CRM).Then,based on the SRM,and CRM,an energy mutual assistance control model between LVSs has been built to optimize energy loss.Finally,in the simulation,compared to the model without pumped storage in the LVS,the SRMand CLRMcan decrease the total energy loss by 294.377 and 432.578 kWh,respectively.The configuration of mPSS can improve the utilization rate of the new energy source generation system,and relieve the pressure of transformer capacity in the LVS.Compared with the SRM,the proposed CRM has reduced the total energy loss by 138.201 kWh,increased the new energy consumption by 161.642 kWh,and decreased the line loss by 7.271 kWh.With the efficiency of the mPSS improving,the total energy loss reduction of CRM will be 3.5 times that of SRM.Further,the CRMcan significantly reduce the reservoir capacity construction of mPSS and ismore suitable for scenarios where the capacity configuration of mPSS is limited.
基金The Key R&D Project of Jilin Province,Grant/Award Number:20230201067GX。
文摘Extracting typical operational scenarios is essential for making flexible decisions in the dispatch of a new power system.A novel deep time series aggregation scheme(DTSAs)is proposed to generate typical operational scenarios,considering the large amount of historical operational snapshot data.Specifically,DTSAs analyse the intrinsic mechanisms of different scheduling operational scenario switching to mathematically represent typical operational scenarios.A Gramian angular summation field-based operational scenario image encoder was designed to convert operational scenario sequences into highdimensional spaces.This enables DTSAs to fully capture the spatiotemporal characteristics of new power systems using deep feature iterative aggregation models.The encoder also facilitates the generation of typical operational scenarios that conform to historical data distributions while ensuring the integrity of grid operational snapshots.Case studies demonstrate that the proposed method extracted new fine-grained power system dispatch schemes and outperformed the latest high-dimensional feature-screening methods.In addition,experiments with different new energy access ratios were conducted to verify the robustness of the proposed method.DTSAs enable dispatchers to master the operation experience of the power system in advance,and actively respond to the dynamic changes of the operation scenarios under the high access rate of new energy.
文摘This study proposes a novel combined primary and secondary control approach for direct current microgrids,specifi-cally in islanded mode.In primary control,this approach establishes an appropriate load power sharing between the distributed energy resources based on their rated power.Simultaneously,it considers the load voltage deviation and provides satisfactory voltage regulation in the secondary control loop.The proposed primary control is based on an efficient droop mechanism that only deploys the local variable measurements,so as to overcome the side effects caused by communication delays.In the case of secondary control,two different methods are devised.In the first,low bandwidth communication links are used to establish the minimum required data transfer between the converters.The effect of communication delay is further explored.The second method excludes any communication link and only uses local variables.Accordingly,a self-sufficient control loop is devised without any communication require-ment.The proposed control notions are investigated in MATLAB/Simulink platform to highlight system performance.The results demonstrate that both proposed approaches can effectively compensate for the voltage deviation due to the primary control task.Detailed comparisons of the two methods are also provided.
文摘Cold thermal energy storage is an active method for reducing the peak electrical demand and electricity consumption of air con-ditioners.This paper investigates two different cases:partial operating mode-load levelling(POM-LL)and demand-limiting mode(DLM).4E(energy,exergy,economic,environment)analyses along with a multi-objective optimization process based on a genetic algorithm is applied to determine optimal design values.Exergy efficiency,total annual cost and payback-period time are considered as objective functions in this study.The results have shown that POM and DLM decreased the electricity consumption by 10.36%and 11.29%,respectively,resulting in raising the annual costs by 11.08%and 11.42%.Also,their annual payback periods were 4.36 and 4.18 years each.In addition,using off-peak hours instead of on-peak hours for electricity consumption and reducing electricity consump-tion are the two main ways of decreasing CO_(2) emissions during electricity generation.Therefore,the CO_(2) emissions through POM and DLM are 13.31%and 13.72%less than those of conventional systems,respectively.
基金Supported by the National Basic Research Program of China under Grant No 2013CB632801the National Key Research and Development Program under Grant No 2016YFB0402303+2 种基金the National Natural Science Foundation of China under Grant Nos61435014,61627822,61574136 and 61306058the Key Projects of Chinese Academy of Sciences under Grant No ZDRW-XH-2016-4the Beijing Natural Science Foundation under Grant No 4162060
文摘We report on the design and fabrication of λ-7.2μm distributed feedback quantum cascade lasers lot very high temperature cw operation and low electrical power consumption. The cw operation is reported above 90℃. For a 2-mm-long and 10-μm-wide laser coated with high-reflectivity on the rear facet, more than 170mW of output power is obtained at 20℃ with a threshold power consumption of 2.4 W, corresponding to 30mW with a threshold power consumption of 3.9 W at 90℃. Robust single-mode emission with a side-mode suppression ratio above 25 dB is continuously tunable by the heat sink temperature or injection current.
基金supported by the National Natural Science Foundation of China(No.51978623).
文摘Light-framed timber structure(LTS)buildings have been highly valued in recent years due to their low-carbon characteristics.However,the applicability of the building envelope is closely related to indoor and outdoor conditions.The hot summer and cold winter(HSCW)climate zone in China has high humidity and great temperature variation throughout the year,resulting in distinct outdoor environments in different seasons.The indoor environment is greatly affected by energy-consumption patterns and window-opening habits,which largely depend upon the regulation operations of occupants.All these interrelated factors lead to extremely complex boundary conditions on each side of the building envelope.Whether the structures of LTS buildings are applicable in this climate zone,therefore,needs to be carefully considered.In this study,two LTS buildings with different envelopes were established in Haining,China,situated in the HSCW climate zone,and selected as the study objects.Different operation modes were adopted to create a variety of indoor environments.Under each condition,the processes of heat and moisture transfer within the building envelopes and the indoor environment were monitored and compared.The comparison indicated that the building envelope with high moisture storage and insulation ability maintained a relatively stable indoor environment,especially when the environment changed abruptly.Conversely,if the outdoor environment was equable(e.g.,relative humidity within the range of 30%–60%)or intermittent energy consumption modes were adopted,the building envelope with a low thermal inertia index and weak moisture-buffering ability performed better because it enabled a faster response of the indoor environment to air conditioning.Moreover,a high risk of moisture accumulation between the thermal insulation layer and other materials with a large water vapour transfer resistance factor was also identified,suggesting a higher requirement for the vapour insulation of the envelopes of LTS buildings.
基金supported in part by the Huxiang Youth Talent Support Program(No.2020RC3030)in part by the Foundation of State Key Laboratory of Pulsed Power Laser Technology(Nos.SKL2021ZR02 and SKL2021KF05)。
文摘To guide the illuminating design to improve the on-state performances of gallium arsenide(GaAs)photoconductive semiconductor switch(PCSS),the effect of spot size on the operation mode of GaAsPCSS based on a semi-insulating wafer with a thickness of 1 mm,triggered by a 1064-nm extrinsic laser beam with the rectangular spot,has been investigated experimentally.It is found that the variation of the spot size in length and width can act on the different parts of the output waveform integrating the characteristics of the linear and nonlinear modes,and then significantly boosts the PCSS toward different operation modes.On this basis,a two-channel model containing the active and passive parts is introduced to interpret the relevant influencing mechanisms.Results indicate that the increased spot length can peak the amplitude of static domains in the active part to enhance the development of the nonlinear switching,while the extended spot width can change the distribution of photogenerated carriers on both parts to facilitate the linear switching and weaken the nonlinear switching,which have been proved by comparing the domain evolutions under different spot sizes.
基金co-supported by the National Key R&D Program of China(No.2020YFC2201001)the Shenzhen Science and Technology Program(No.20210623091808026).
文摘The bipolar ionic liquid thruster employs ionic liquid as a propellant to discharge positively and negatively charged high-energy particles under an alternating current(AC)power source,effectively suppressing electrochemical reaction and ensuring charge neutrality.Determining an optimal AC supply power source frequency is critical for sustained stable thruster operation.This study focuses on the emission characteristics of the ionic liquid thruster under varied AC conditions.The AC power supply was set within the frequency range of 0.5-64 Hz,with eight specific frequency conditions selected for experimentation.The experimental results indicate that the thruster operates steadily within a voltage range of±1470 to±1920 V,with corresponding positive polarity current ranging from 0.41 to 4.91μA and negative polarity current ranging from−0.49 to−4.10μA.During voltage polarity switching,an emission delay occurs,manifested as a prominent peak signal caused by circuit capacitance characteristics and a minor peak signal resulting from liquid droplets.Extended emission test was conducted at 16 Hz,demonstrating approximately 1 h and 50 min of consistent emission before intermittent discharge.These findings underscore the favorable impact of AC conditions within the 8-16 Hz range on the self-neutralization capability of the ionic liquid thruster.
基金supported financially by State Grid Henan Electric Power Company Technology Project“Research on System Cost Impact Assessment and Sharing Mechanism under the Rapid Development of Distributed Photovoltaics”(Grant Number:5217L0220021).
文摘As the Chinese government proposes ambitious plans to promote low-carbon transition,energy storage will play a pivotal role in China’s future power system.However,due to the lack of a mature electricity market environment and corresponding mechanisms,current energy storage in China faces problems such as unclear operational models,insufficient cost recovery mechanisms,and a single investment entity,making it difficult to support the rapid development of the energy storage industry.In contrast,European and American countries have already embarked on certain practices in energy storage operation models.Through exploration of key issues such as investment entities,market participation forms,and cost recovery channels in both front and back markets,a wealth of mature experiences has been accumulated.Therefore,this paper first summarizes the existing practices of energy storage operation models in North America,Europe,and Australia’s electricity markets separately from front and back markets,finding that perfect market mechanisms and reasonable subsidy policies are among the main drivers for promoting the rapid development of energy storage markets.Subsequently,combined with the actual development of China’s electricity market,it explores three key issues affecting the construction of costsharing mechanisms for energy storage under market conditions:Market participation forms,investment and operation modes,and cost recovery mechanisms.Finally,in line with the development expectations of China’s future electricitymarket,suggestions are proposed fromfour aspects:Market environment construction,electricity price formation mechanism,cost sharing path,and policy subsidy mechanism,to promote the healthy and rapid development of China’s energy storage industry.
文摘Power flow adjustment is a sequential decision problem.The operator makes decisions to ensure that the power flow meets the system's operational constraints,thereby obtaining a typical operating mode power flow.However,this decision-making method relies heavily on human experience,which is inefficient when the system is complex.In addition,the results given by the current evaluation system are difficult to directly guide the intelligent power flow adjustment.In order to improve the efficiency and intelligence of power flow adjustment,this paper proposes a power flow adjustment method based on deep reinforcement learning.Combining deep reinforcement learning theory with traditional power system operation mode analysis,the concept of region mapping is proposed to describe the adjustment process,so as to analyze the process of power flow calculation and manual adjustment.Considering the characteristics of power flow adjustment,a Markov decision process model suitable for power flow adjustment is constructed.On this basis,a double Q network learning method suitable for power flow adjustment is proposed.This method can adjust the power flow according to the set adjustment route,thus improving the intelligent level of power flow adjustment.The method in this paper is tested on China Electric Power Research Institute(CEPRI)test system.
基金Project(61374140)supported by the National Natural Science Foundation of China
文摘There are multiple operating modes in the real industrial process, and the collected data follow the complex multimodal distribution, so most traditional process monitoring methods are no longer applicable because their presumptions are that sampled-data should obey the single Gaussian distribution or non-Gaussian distribution. In order to solve these problems, a novel weighted local standardization(WLS) strategy is proposed to standardize the multimodal data, which can eliminate the multi-mode characteristics of the collected data, and normalize them into unimodal data distribution. After detailed analysis of the raised data preprocessing strategy, a new algorithm using WLS strategy with support vector data description(SVDD) is put forward to apply for multi-mode monitoring process. Unlike the strategy of building multiple local models, the developed method only contains a model without the prior knowledge of multi-mode process. To demonstrate the proposed method's validity, it is applied to a numerical example and a Tennessee Eastman(TE) process. Finally, the simulation results show that the WLS strategy is very effective to standardize multimodal data, and the WLS-SVDD monitoring method has great advantages over the traditional SVDD and PCA combined with a local standardization strategy(LNS-PCA) in multi-mode process monitoring.
基金Supported by the Science and Technology Project of Yunnan Tobacco Co.,Ltd.(2016YN01)~~
文摘With the gradually popularization of replacing coal tobacco leaf flue-curing technology with biomass fuel, the operation of raw materials collection and transportation links faces many problems. In this paper, the existing problems in view of biomass fuel operation dominated by tobacco straw in current tobacco leaf flue-curing were analyzed, and the 3 kinds of fuel operation modes （＂contracting processing mode, displacement mode and commercialization mode＂） were put forward, each of which was also briefly analyzed, with the aim to expand the way of thinking about biomass raw materials processing by cooperative organization.
基金supported by the Institute of Information&communications Technology Planning&Evaluation(IITP)grant funded by the Korea government(MSIT)(RS-2024-00399401,Development of Quantum-Safe Infrastructure Migration and Quantum Security Verification Technologies).
文摘With the rise of remote collaboration,the demand for advanced storage and collaboration tools has rapidly increased.However,traditional collaboration tools primarily rely on access control,leaving data stored on cloud servers vulnerable due to insufficient encryption.This paper introduces a novel mechanism that encrypts data in‘bundle’units,designed to meet the dual requirements of efficiency and security for frequently updated collaborative data.Each bundle includes updated information,allowing only the updated portions to be reencrypted when changes occur.The encryption method proposed in this paper addresses the inefficiencies of traditional encryption modes,such as Cipher Block Chaining(CBC)and Counter(CTR),which require decrypting and re-encrypting the entire dataset whenever updates occur.The proposed method leverages update-specific information embedded within data bundles and metadata that maps the relationship between these bundles and the plaintext data.By utilizing this information,the method accurately identifies the modified portions and applies algorithms to selectively re-encrypt only those sections.This approach significantly enhances the efficiency of data updates while maintaining high performance,particularly in large-scale data environments.To validate this approach,we conducted experiments measuring execution time as both the size of the modified data and the total dataset size varied.Results show that the proposed method significantly outperforms CBC and CTR modes in execution speed,with greater performance gains as data size increases.Additionally,our security evaluation confirms that this method provides robust protection against both passive and active attacks.
基金supported by the National Natural Science Foundation of China(Grant No.51105386)the National Deep-Sea Technology Project of Development and Research(Grant No.DYXM-115-04-02-01)the Fundamental Research Funds for the Central Universities(Grant No.2011QNZT058)
文摘An integrated dynamic model of China＇s deep ocean mining system is developed and the fast simulation analysis of its longitudinal reciprocating motion operation processes is achieved. The seafloor tracked miner is built as a three-dimensional single-body model with six-degree-of-freedom. The track-terrain interaction is modeled by partitioning the track-terrain interface into a certain number of mesh elements with three mutually perpendicular forces, including the normal force, the longitudinal shear force and the lateral shear force, acting on the center point of each mesh element. The hydrodynamic force of the miner is considered and applied. By considering the operational safety and collection efficiency, two new mining paths for the miner on the seafloor are proposed, which can be simulated with the established single-body dynamic model of the miner. The pipeline subsystem is built as a three-dimensional multi-body discrete element model, which is divided into rigid elements linked by flexible connectors. The flexible connector without mass is represented by six spring-damper elements. The external hydrodynamic forces of the ocean current from the longitudinal and lateral directions are both considered and modeled based on the Morison formula and applied to the mass center of each corresponding discrete rigid element. The mining ship is simplified and represented by a general kinematic point, whose heave motion induced by the ocean waves and the longitudinal and lateral towing motions are considered and applied. By integrating the single-body dynamic model of the miner and the multi-body discrete element dynamic model of the pipeline, and defining the kinematic equations of the mining ship, the integrated dynamic model of the total deep ocean mining system is formed. The longitudinal reciprocating motion operation modes of the total mining system, which combine the active straight-line and turning motions of the miner and the ship, and the passive towed motions of the pipeline, are proposed and simulated with the developed 3D dynamic model. Some critical simulation results are obtained and analyzed, such as the motion trajectories of key subsystems, the velocities of the buoyancy modules and the interaction forces between subsystems, which in a way can provide important theoretical basis and useful technical reference for the practical deep ocean mining system analysis, operation and control.
基金supported by National Natural Science Foundation of China(Nos.11475043 and 11375042)
文摘The discharge operation regime of pulse modulated atmospheric radio frequency （RF） glow discharge in helium is investigated on the duty cycle and frequency of modulation pulses. The characteristics of radio frequency discharge burst in terms of breakdown voltage, alpha（s）- gamma（γ） mode transition voltage and current are demonstrated by the discharge current voltage characteristics. The minimum breakdown voltage of RF discharge burst was obtained at the duty cycle of 20% and frequency of 400 kHz, respectively. The α-γ mode transition of RF discharge burst occurs at higher voltage and current by reducing the duty cycle and elevating the modulation frequency before the RF discharge burst evolving into the ignition phase, in which the RF discharge burst can operate stably in the γ mode. It proposes that the intensity and stability of RF discharge burst can be improved by manipulating the duty cycle and modulation frequency in pulse modulated atmospheric RF glow discharge.
文摘Virtual supply chain, as a modern collaborative mode of enterprises, is important to decrease the cost and improve the efficiency and the quality of supply chains, and to satisfy customers. Based on the analysis of the conception and characteristics of the virtual supply chain, the architecture of virtual supply chain is built, and corresponding objects, tasks, information and technologies are described. Three operation modes-Order-driven, manufacturer-centered, and retailer-centered are researched. As a case, virtual supply chain is applied in the electronic commerce and networked customization system of ceramic products.
基金supported by National Natural Science Foundation of China(51576174)
文摘The effects of feed gas flow rate and operating current on the electrical characteristics and dynamic behavior of a rotating gliding arc （RGA） plasma codriven by a magnetic field and tangential flow were investigated.The operating current has been shown to significantly affect the time-resolved voltage waveforms of the discharge,particularly at flow rate =21 min^-1.When the current was lower than 140 mA,sinusoidal waveforms with regular variation periods of 13.5-17.0 ms can be observed （flow rate =21 min^-1）.The restrike mode characterized by serial sudden drops of voltage appeared under all studied conditions.Increasing the flow rate from 8 to 121 min^-1 （at the same current） led to a shift of arc rotation mode which would then result in a significant drop of discharge voltage （around 120-200 V）.For a given flow rate,the reduction of current resulted in a nearly linear increase of voltage.
