We give a new result on the construction of K-frame generators for unitary systems by using the pseudo-inverses of involved operators,which provides an improvement to one known result on this topic.We also introduce t...We give a new result on the construction of K-frame generators for unitary systems by using the pseudo-inverses of involved operators,which provides an improvement to one known result on this topic.We also introduce the concept of K-woven generators for unitary systems,by means of which we investigate the weaving properties of K-frame generators for unitary systems.展开更多
This review paper examines the various types of electrical generators used to convert wave energy into electrical energy.The focus is on both linear and rotary generators,including their design principles,operational ...This review paper examines the various types of electrical generators used to convert wave energy into electrical energy.The focus is on both linear and rotary generators,including their design principles,operational efficiencies,and technological advancements.Linear generators,such as Induction,permanent magnet synchronous,and switched reluctance types,are highlighted for their direct conversion capability,eliminating the need for mechanical gearboxes.Rotary Induction generators,permanent magnet synchronous generators,and doubly-fed Induction generators are evaluated for their established engineering principles and integration with existing grid infrastructure.The paper discusses the historical development,environmental benefits,and ongoing advancements in wave energy technologies,emphasizing the increasing feasibility and scalability of wave energy as a renewable source.Through a comprehensive analysis,this review provides insights into the current state and future prospects of electrical generators in wave energy conversion,underscoring their potential to significantly reduce reliance on fossil fuels and mitigate environmental impacts.展开更多
To address the excessive complexity of monthly scheduling and the impact of uncertain net load on the chargeable energy of storage,a reduced time-period monthly scheduling model for thermal generators and energy stora...To address the excessive complexity of monthly scheduling and the impact of uncertain net load on the chargeable energy of storage,a reduced time-period monthly scheduling model for thermal generators and energy storage,incorporating daily minimum chargeable energy constraints,was developed.Firstly,considering the variations in the frequency of unit start-ups and shutdowns under different levels of net load fluctuation,a method was proposed to reduce decision time periods for unit start-up and shut-down operations.This approach,based on the characteristics of net load fluctuations,minimizes the decision variables of units,thereby simplifying the monthly schedulingmodel.Secondly,the relationship between energy storage charging and discharging power,net load,and the total maximum/minimum output of units was analyzed.Based on this,daily minimum chargeable energy constraints were established to ensure the energy storage system meets charging requirements under extreme net load scenarios.Finally,taking into account the operational costs of thermal generators and energy storage,load loss costs,and operational constraints,the reduced time-period monthly schedulingmodel was constructed.Case studies demonstrate that the proposedmethod effectively generates economical monthly operation plans for thermal generators and energy storage,significantly reduces model solution time,and satisfies the charging requirements of energy storage under extreme net load conditions.展开更多
Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is p...Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is proposed.The electric field applied between the template and the substrate drives the contact,tilting,filling,and holding processes.By accurately controlling the introduced included angle between the flexible template and the substrate,tilted nanostructures with a controllable angle are imprinted onto the substrate,although they are vertical on the template.By flexibly adjusting the electric field intensity and the included angle,large-area uniform-tilted,gradient-tilted,and high-angle-tilted nanostructures are fabricated.In contrast to traditional replication,the morphology of the nanoimprinting structure is extended to customized control.This work provides a cost-effective,efficient,and versatile technology for the fabrication of various large-area tilted metasurface structures.As an illustration,a tilted nanograting with a high coupling efficiency is fabricated and integrated into augmented reality displays,demonstrating superior imaging quality.展开更多
Recommending personalized travel routes from sparse,implicit feedback poses a significant challenge,as conventional systems often struggle with information overload and fail to capture the complex,sequential nature of...Recommending personalized travel routes from sparse,implicit feedback poses a significant challenge,as conventional systems often struggle with information overload and fail to capture the complex,sequential nature of user preferences.To address this,we propose a Conditional Generative Adversarial Network(CGAN)that generates diverse and highly relevant itineraries.Our approach begins by constructing a conditional vector that encapsulates a user’s profile.This vector uniquely fuses embeddings from a Heterogeneous Information Network(HIN)to model complex user-place-route relationships,a Recurrent Neural Network(RNN)to capture sequential path dynamics,and Neural Collaborative Filtering(NCF)to incorporate collaborative signals from the wider user base.This comprehensive condition,further enhanced with features representing user interaction confidence and uncertainty,steers a CGAN stabilized by spectral normalization to generate high-fidelity latent route representations,effectively mitigating the data sparsity problem.Recommendations are then formulated using an Anchor-and-Expand algorithm,which selects relevant starting Points of Interest(POI)based on user history,then expands routes through latent similarity matching and geographic coherence optimization,culminating in Traveling Salesman Problem(TSP)-based route optimization for practical travel distances.Experiments on a real-world check-in dataset validate our model’s unique generative capability,achieving F1 scores ranging from 0.163 to 0.305,and near-zero pairs−F1 scores between 0.002 and 0.022.These results confirm the model’s success in generating novel travel routes by recommending new locations and sequences rather than replicating users’past itineraries.This work provides a robust solution for personalized travel planning,capable of generating novel and compelling routes for both new and existing users by learning from collective travel intelligence.展开更多
Remote sensing image super-resolution technology is pivotal for enhancing image quality in critical applications including environmental monitoring,urban planning,and disaster assessment.However,traditional methods ex...Remote sensing image super-resolution technology is pivotal for enhancing image quality in critical applications including environmental monitoring,urban planning,and disaster assessment.However,traditional methods exhibit deficiencies in detail recovery and noise suppression,particularly when processing complex landscapes(e.g.,forests,farmlands),leading to artifacts and spectral distortions that limit practical utility.To address this,we propose an enhanced Super-Resolution Generative Adversarial Network(SRGAN)framework featuring three key innovations:(1)Replacement of L1/L2 loss with a robust Charbonnier loss to suppress noise while preserving edge details via adaptive gradient balancing;(2)A multi-loss joint optimization strategy dynamically weighting Charbonnier loss(β=0.5),Visual Geometry Group(VGG)perceptual loss(α=1),and adversarial loss(γ=0.1)to synergize pixel-level accuracy and perceptual quality;(3)A multi-scale residual network(MSRN)capturing cross-scale texture features(e.g.,forest canopies,mountain contours).Validated on Sentinel-2(10 m)and SPOT-6/7(2.5 m)datasets covering 904 km2 in Motuo County,Xizang,our method outperforms the SRGAN baseline(SR4RS)with Peak Signal-to-Noise Ratio(PSNR)gains of 0.29 dB and Structural Similarity Index(SSIM)improvements of 3.08%on forest imagery.Visual comparisons confirm enhanced texture continuity despite marginal Learned Perceptual Image Patch Similarity(LPIPS)increases.The method significantly improves noise robustness and edge retention in complex geomorphology,demonstrating 18%faster response in forest fire early warning and providing high-resolution support for agricultural/urban monitoring.Future work will integrate spectral constraints and lightweight architectures.展开更多
How to operate^(82)Sr/^(82)Rb and ^(68)Ge/^(68)Ga generators used in the positron emission tomography scan process is explained, and the importance of ^(82)Sr and ^(68)Ge radionuclides for these generators is revealed...How to operate^(82)Sr/^(82)Rb and ^(68)Ge/^(68)Ga generators used in the positron emission tomography scan process is explained, and the importance of ^(82)Sr and ^(68)Ge radionuclides for these generators is revealed. To produce medical ^(82)Sr and ^(68)Ge by means of a proton accelerator in an irradiation time of 24 h, a proton beam current of250 l A, and an energy range E_(proton)= 100 →5 MeV, the cross sections and the neutron emission spectrum curves of(p,xn) reaction processes on Rb-85, Ga-69 and Ga-71 targets were calculated, and the activities and yields of the product were simulated for the reaction processes. Additionally, the integral yields of the reaction processes were determined via the calculated cross-sectional curves and the mass stopping power obtained from the X-PMSP program. Furthermore, based on the obtained results, the appropriate reaction processes for the production of ^(82)Sr and ^(68)Ge isotopes on Rb-85, Ga-69, and Ga-71 targets are discussed.展开更多
In this paper, a design method for ocean wave permanent magnet synchronous generator(PMSG)is proposed with new performance criteria to obtain better output performance at the cost of less permanent magnet material. Be...In this paper, a design method for ocean wave permanent magnet synchronous generator(PMSG)is proposed with new performance criteria to obtain better output performance at the cost of less permanent magnet material. Besides, a simple equivalent analytical geometry method is put forward to calculate the sizes of permanent magnets. Based on geometric and electromagnetic models, four types of rotor structures are compared, i.e., embedded, tangential, tile surface mount and convex surface mount structures. The designs and comparisons of machine are performed with the same permanent magnet volume. Moreover, the influences of mechanical pole-arc coefficient of tile surface mount PMSG on electrical efficiency, output power, material corrosion, core loss, and torque ripple are investigated. Finite-element analysis method is applied to verify the results using Ansoft/Maxwell.展开更多
A data acquisition system for testing gas sensor array response to multi-gas is presented.The testing system is based on the character of the gas response of metal oxide semiconductor gas sensor array.The data acquisi...A data acquisition system for testing gas sensor array response to multi-gas is presented.The testing system is based on the character of the gas response of metal oxide semiconductor gas sensor array.The data acquisition is realized automatically through the real time controlling of the data acquisition card PCI1711.This system is highly attractive for electronic nose,which is a powerful tool for the discrimination of gases.展开更多
All modes of operation of a two-capacitor generator based on overflow of the charge accumulated in capacitors through the load resistance between two capacitors with antiphase modulated capacitances by means of in-pla...All modes of operation of a two-capacitor generator based on overflow of the charge accumulated in capacitors through the load resistance between two capacitors with antiphase modulated capacitances by means of in-plane or out-of-plane shift of the electrode plates under action of a mechanical force are analyzed paying the especial attention to fabrication of the generators with small sizes. Numerical solutions for all the modes are obtained, and they are found to be universal. Analytical estimates of the maximum power of the generator as a function of the capacitances modulation factor are derived. Experimental investigations of a two-capacitor rotational electric generator show that its characteristics are consistent with the analysis performed and that this analysis can be used to describe all specific features of operation of particular generators. Applications of the devices in micro-design for feeding the remote sensors are discussed.展开更多
This paper studied the direct-drive permanent magnet synchronous machine (permanent magnet synchronous generator, PMSG) Chopper optimal topology and resistance value. Compared the different Chopper circuit low voltage...This paper studied the direct-drive permanent magnet synchronous machine (permanent magnet synchronous generator, PMSG) Chopper optimal topology and resistance value. Compared the different Chopper circuit low voltage ride-through capability in the same grid fault conditions in simulation. This paper computes the dump resistance ceiling according to the power electronic devices and over-current capability. Obtaining the dump resistance low limit according to the temperature resistance allows, and calculating the optimal value by drop voltage in the DC-Bus during the fault. The feasibility of the proposed algorithm is verified by simulation results.展开更多
An analytic electromagnetic calculation method for doubly fed induction generator(DFIG) in wind turbine system was presented. Based on the operation principles, steady state equivalent circuit and basic equations of D...An analytic electromagnetic calculation method for doubly fed induction generator(DFIG) in wind turbine system was presented. Based on the operation principles, steady state equivalent circuit and basic equations of DFIG, the modeling for electromagnetic calculation of DFIG was proposed. The electromagnetic calculation of DFIG was divided into three steps: the magnetic flux calculation, parameters derivation and performance checks. For each step, the detailed numeric calculation formulas were all derived. Combining the calculation formulas, the whole electromagnetic calculation procedure was established, which consisted of three iterative calculation loops, including magnetic saturation coefficient, electromotive force and total output power. All of the electromagnetic and performance data of DIFG can be calculated conveniently by the established calculation procedure, which can be used to evaluate the new designed machine. A 1.5 MW DFIG designed by the proposed procedure was built, for which the whole type tests including no-load test, load test and temperature rising test were carried out. The test results have shown that the DFIG satisfies technical requirements and the test data fit well with the calculation results which prove the correctness of the presented calculation method.展开更多
Based on Hamiltonian formulation, this paper proposes a design approach to nonlinear feedback excitation control of synchronous generators with steam valve control, disturbances and unknown parameters. It is shown tha...Based on Hamiltonian formulation, this paper proposes a design approach to nonlinear feedback excitation control of synchronous generators with steam valve control, disturbances and unknown parameters. It is shown that the dynamics of the synchronous generators can be expressed as a dissipative Hamiltonian system, based on which an adaptive H-infinity controller is then designed for the systems by using the structure properties of dissipative Hamiltonian systems. Simulations show that the controller obtained in this paper is very effective.展开更多
By adopting various stochastic weather generators, different research groups in their recent studies have realized the importance of the effects of climatic variability on crop growth and development. The conventional...By adopting various stochastic weather generators, different research groups in their recent studies have realized the importance of the effects of climatic variability on crop growth and development. The conventional assessments derived climate change scenarios from General Circulation Models (GCMs) experiments, however, are incapable of helping to understand this importance. The particular interest here is to review the general methodological scheme to incorporate stochastic weather generator into climate impact studies and the specific approaches in our studies, and put forward uncertainties that still exist. A variety of approaches have been taken to develop the parameterization program and stochastic experiment, and adjust the parameters of atypical stochastic weather generator called WGEN. Usually, the changes in monthly means and variances of weather variables between controlled and changed climate are used to perturb the parameters to generate the intended daily climate scenarios. We establish a parameterization program and methods for stochastic experiment of WGEN in the light of outputs of short-term climate prediction models, and evaluate its simulations on both temporal and spatial scales. Also, we manipulated parameters in relation to the changes in precipitation to produce the intended types and qualitative magnitudes of climatic variability. These adjustments yield various changes in climatic variability for sensitivity analyses. The impacts of changes in climatic variability on maize growth, final yield, and agro-climatic resources in Northeast China are assessed and presented as the case studies through the above methods. However, this corporation is still equivocal due to deficiencies of the generator and unsophisticated manipulation of parameters. To detect and simulate the changes in climatic variability is one of the indispensable ways to reduce the uncertainties in this aspect.展开更多
The chaos-based feedforward output functions for combining keystream generators are proposed according to chaotic dynamic theory. The generated binary signals are independently and identically distributed, and have pr...The chaos-based feedforward output functions for combining keystream generators are proposed according to chaotic dynamic theory. The generated binary signals are independently and identically distributed, and have predictable periods. All experiments correspond to the theoretical prediction very well.展开更多
A series of D-π-A type sulfonium salt photoacid generators with different π-conjugated structures, such as triphenyl, phenylstilbene, styryl-biphenyl, and stilbene, were designed to determine the effect of molecular...A series of D-π-A type sulfonium salt photoacid generators with different π-conjugated structures, such as triphenyl, phenylstilbene, styryl-biphenyl, and stilbene, were designed to determine the effect of molecular structures on the photochemical and photophysical properties. The mechanisms of photochemical generation of H＋ were studied by UV-Vis spectroscopy, theoretical calculations, and fluorescence spectroscopy. It is found that the frontier orbits determine the absorption, the molar extinction coefficients, and the quantum yields of photoacid generation. Triphenyl systems connected with sulfonium are beneficial to increase the quantum yields of acid generation. The photoreactivity of four sulfonium salts was further evaluated through the polymerizations of various epoxide monomers at different irradiation wavelengths （365- 425 nm） by using the real-time infrared spectroscopy with light-emitting diodes. The high quantum yields for acid generation （ФH＋ = -0.32 to 0.58） and the high molar extinction coefficients （ε = -23500 L.mol-1.cm-1 to 31000 L.mol-1.cm-1） of the sulfonium salts lead to high conversion rates （over 50%-80%）. Hence, these photoinitiators exhibit potential for the photocuring applications.展开更多
To satisfy the requirements of practical applications,thermoelectric generators should be highly efficient and mechanically robust.Recently,progress in designing high-performance thermoelectric generators has been mad...To satisfy the requirements of practical applications,thermoelectric generators should be highly efficient and mechanically robust.Recently,progress in designing high-performance thermoelectric generators has been made.However,the mechanical properties of thermoelectric generators are still unsatisfactory.In this review,studies on the mechanical properties of thermoelectric generators are summarized.The me-chanical properties of bulk thermoelectric generators will be first discussed.In this section,the mechan-ical properties of thermoelectric materials and the strategies for improving their mechanical properties are emphasized.Since the device’s failure usually occurs at the interface between the thermoelectric ma-terials and electrode,the joint strength of electrodes and thermoelectric materials will be overviewed.After that,the mechanical properties of the inorganic thin-film thermoelectric devices will be discussed.Since the figure of merit for the flexibility of thermoelectric materials depends on the film thickness,elastic modulus,and yield strength,the synthesis methods of thin-film thermoelectric materials will be reviewed.Finally,this review will be concluded with a discussion on flexible organic thermoelectric de-vices and flexible devices using bulk legs.展开更多
Chemical oxygen generators(COGs)have been used worldwide in confined spaces as an emergency oxygen supply technology,mainly because they are independent and have a long shelf life.However,a number of challenges relate...Chemical oxygen generators(COGs)have been used worldwide in confined spaces as an emergency oxygen supply technology,mainly because they are independent and have a long shelf life.However,a number of challenges related to COGs remain unsolved,and a literature review of the current state of the technology is needed.First,the present article summarizes the basic information and applications of COGs,including their oxygen production mechanism,components,forming technology,and ignition system.Four current challenges encountered in applying COGs are discussed,along with the strategies adopted thus far to solve these problems,as found in the published literature.The literature survey reveals that,although much effort has been devoted to controlling the oxygen production rate and the heat output of COGs,the mechanism of producing toxic gases remains unclear and a reliable and safe ignition system has not been fully developed.Finally,future opportunities in the development of COGs are briefly listed.展开更多
With the rapid increase of wind farms,the grid code needs to be improved to meet the requirement of wind farms and enhance grid stability.Doubly-fed induction generators are largely used in wind turbines,but they are ...With the rapid increase of wind farms,the grid code needs to be improved to meet the requirement of wind farms and enhance grid stability.Doubly-fed induction generators are largely used in wind turbines,but they are very sensitive to grid disturbances.The voltage swell can be caused by switching on capacitor banks or switching off large loads,which may result in the reversal of the power flow in the grid convertor;the current may flow from the grid into the DC link,which may step up DC voltage,and result in large faults of rotor currents and instantaneous power oscillation.The grid reactive compensation devices can not have the automatic swithing function after the low voltage fault,which will result in local reactive power surplus,so some wind power generators will retreat from the grid under high voltage protection.展开更多
Solar evaporation is recognized as a prospective technique to produce freshwater from non-drinkable water using inexhaustible solar energy.However,it remains a challenge to fabricate low-cost solar evaporators with ob...Solar evaporation is recognized as a prospective technique to produce freshwater from non-drinkable water using inexhaustible solar energy.However,it remains a challenge to fabricate low-cost solar evaporators with obviously reduced water evaporation enthalpy to achieve high evaporation rates.Herein,N,O dual-doped carbon foam(NCF)is fabricated from the lowtemperature carbonization of poly(ethylene terephthalate)(PET)waste by melamine/molten salts at 340℃.During carbonization,melamine reacts with carboxylic acids of PET degradation products to yield a crosslinking network,and then molten salts catalyze the decarboxylation and dehydration to construct a stable framework.Owing to rich N,O-containing groups,3D interconnected pores,super-hydrophilicity,and ultra-low thermal conductivity(0.0599 W m^(−1) K^(−1)),NCF not only achieves high light absorbance(ca.99%)and solar-to-thermal conversion,but also promotes the formation of water cluster to reduce water evaporation enthalpy by ca.37%.Consequently,NCF exhibits a high evaporation rate(2.4 kg m^(−2) h^(−1)),surpassing the-state-of-the-art solar evaporators,and presents good antiacid/basic abilities,long-term salt-resistance,and self-cleaning ability.Importantly,a large-scale NCF-based outdoor solar desalination device is developed to produce freshwater.The daily freshwater production amount per unit area(6.3 kg)meets the two adults’daily water consumption.The trash-to-treasure strategy will give impetus to the development of low-cost,advanced solar evaporators from waste plastics for addressing the global freshwater shortage.展开更多
基金Supported by NSFC(Nos.12361028,11761057)Science Foundation of Jiangxi Education Department(Nos.GJJ202302,GJJ202303,GJJ202319).
文摘We give a new result on the construction of K-frame generators for unitary systems by using the pseudo-inverses of involved operators,which provides an improvement to one known result on this topic.We also introduce the concept of K-woven generators for unitary systems,by means of which we investigate the weaving properties of K-frame generators for unitary systems.
文摘This review paper examines the various types of electrical generators used to convert wave energy into electrical energy.The focus is on both linear and rotary generators,including their design principles,operational efficiencies,and technological advancements.Linear generators,such as Induction,permanent magnet synchronous,and switched reluctance types,are highlighted for their direct conversion capability,eliminating the need for mechanical gearboxes.Rotary Induction generators,permanent magnet synchronous generators,and doubly-fed Induction generators are evaluated for their established engineering principles and integration with existing grid infrastructure.The paper discusses the historical development,environmental benefits,and ongoing advancements in wave energy technologies,emphasizing the increasing feasibility and scalability of wave energy as a renewable source.Through a comprehensive analysis,this review provides insights into the current state and future prospects of electrical generators in wave energy conversion,underscoring their potential to significantly reduce reliance on fossil fuels and mitigate environmental impacts.
基金This study was supported by State Grid Corporation headquarters technology project(4000-202399368A-2-2-ZB).
文摘To address the excessive complexity of monthly scheduling and the impact of uncertain net load on the chargeable energy of storage,a reduced time-period monthly scheduling model for thermal generators and energy storage,incorporating daily minimum chargeable energy constraints,was developed.Firstly,considering the variations in the frequency of unit start-ups and shutdowns under different levels of net load fluctuation,a method was proposed to reduce decision time periods for unit start-up and shut-down operations.This approach,based on the characteristics of net load fluctuations,minimizes the decision variables of units,thereby simplifying the monthly schedulingmodel.Secondly,the relationship between energy storage charging and discharging power,net load,and the total maximum/minimum output of units was analyzed.Based on this,daily minimum chargeable energy constraints were established to ensure the energy storage system meets charging requirements under extreme net load scenarios.Finally,taking into account the operational costs of thermal generators and energy storage,load loss costs,and operational constraints,the reduced time-period monthly schedulingmodel was constructed.Case studies demonstrate that the proposedmethod effectively generates economical monthly operation plans for thermal generators and energy storage,significantly reduces model solution time,and satisfies the charging requirements of energy storage under extreme net load conditions.
基金supported by National Natural Science Foundation of China(No.52025055 and 52275571)Basic Research Operation Fund of China(No.xzy012024024).
文摘Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is proposed.The electric field applied between the template and the substrate drives the contact,tilting,filling,and holding processes.By accurately controlling the introduced included angle between the flexible template and the substrate,tilted nanostructures with a controllable angle are imprinted onto the substrate,although they are vertical on the template.By flexibly adjusting the electric field intensity and the included angle,large-area uniform-tilted,gradient-tilted,and high-angle-tilted nanostructures are fabricated.In contrast to traditional replication,the morphology of the nanoimprinting structure is extended to customized control.This work provides a cost-effective,efficient,and versatile technology for the fabrication of various large-area tilted metasurface structures.As an illustration,a tilted nanograting with a high coupling efficiency is fabricated and integrated into augmented reality displays,demonstrating superior imaging quality.
基金supported by the Chung-Ang University Research Grants in 2023.Alsothe work is supported by the ELLIIT Excellence Center at Linköping–Lund in Information Technology in Sweden.
文摘Recommending personalized travel routes from sparse,implicit feedback poses a significant challenge,as conventional systems often struggle with information overload and fail to capture the complex,sequential nature of user preferences.To address this,we propose a Conditional Generative Adversarial Network(CGAN)that generates diverse and highly relevant itineraries.Our approach begins by constructing a conditional vector that encapsulates a user’s profile.This vector uniquely fuses embeddings from a Heterogeneous Information Network(HIN)to model complex user-place-route relationships,a Recurrent Neural Network(RNN)to capture sequential path dynamics,and Neural Collaborative Filtering(NCF)to incorporate collaborative signals from the wider user base.This comprehensive condition,further enhanced with features representing user interaction confidence and uncertainty,steers a CGAN stabilized by spectral normalization to generate high-fidelity latent route representations,effectively mitigating the data sparsity problem.Recommendations are then formulated using an Anchor-and-Expand algorithm,which selects relevant starting Points of Interest(POI)based on user history,then expands routes through latent similarity matching and geographic coherence optimization,culminating in Traveling Salesman Problem(TSP)-based route optimization for practical travel distances.Experiments on a real-world check-in dataset validate our model’s unique generative capability,achieving F1 scores ranging from 0.163 to 0.305,and near-zero pairs−F1 scores between 0.002 and 0.022.These results confirm the model’s success in generating novel travel routes by recommending new locations and sequences rather than replicating users’past itineraries.This work provides a robust solution for personalized travel planning,capable of generating novel and compelling routes for both new and existing users by learning from collective travel intelligence.
基金This study was supported by:Inner Mongolia Academy of Forestry Sciences Open Research Project(Grant No.KF2024MS03)The Project to Improve the Scientific Research Capacity of the Inner Mongolia Academy of Forestry Sciences(Grant No.2024NLTS04)The Innovation and Entrepreneurship Training Program for Undergraduates of Beijing Forestry University(Grant No.X202410022268).
文摘Remote sensing image super-resolution technology is pivotal for enhancing image quality in critical applications including environmental monitoring,urban planning,and disaster assessment.However,traditional methods exhibit deficiencies in detail recovery and noise suppression,particularly when processing complex landscapes(e.g.,forests,farmlands),leading to artifacts and spectral distortions that limit practical utility.To address this,we propose an enhanced Super-Resolution Generative Adversarial Network(SRGAN)framework featuring three key innovations:(1)Replacement of L1/L2 loss with a robust Charbonnier loss to suppress noise while preserving edge details via adaptive gradient balancing;(2)A multi-loss joint optimization strategy dynamically weighting Charbonnier loss(β=0.5),Visual Geometry Group(VGG)perceptual loss(α=1),and adversarial loss(γ=0.1)to synergize pixel-level accuracy and perceptual quality;(3)A multi-scale residual network(MSRN)capturing cross-scale texture features(e.g.,forest canopies,mountain contours).Validated on Sentinel-2(10 m)and SPOT-6/7(2.5 m)datasets covering 904 km2 in Motuo County,Xizang,our method outperforms the SRGAN baseline(SR4RS)with Peak Signal-to-Noise Ratio(PSNR)gains of 0.29 dB and Structural Similarity Index(SSIM)improvements of 3.08%on forest imagery.Visual comparisons confirm enhanced texture continuity despite marginal Learned Perceptual Image Patch Similarity(LPIPS)increases.The method significantly improves noise robustness and edge retention in complex geomorphology,demonstrating 18%faster response in forest fire early warning and providing high-resolution support for agricultural/urban monitoring.Future work will integrate spectral constraints and lightweight architectures.
文摘How to operate^(82)Sr/^(82)Rb and ^(68)Ge/^(68)Ga generators used in the positron emission tomography scan process is explained, and the importance of ^(82)Sr and ^(68)Ge radionuclides for these generators is revealed. To produce medical ^(82)Sr and ^(68)Ge by means of a proton accelerator in an irradiation time of 24 h, a proton beam current of250 l A, and an energy range E_(proton)= 100 →5 MeV, the cross sections and the neutron emission spectrum curves of(p,xn) reaction processes on Rb-85, Ga-69 and Ga-71 targets were calculated, and the activities and yields of the product were simulated for the reaction processes. Additionally, the integral yields of the reaction processes were determined via the calculated cross-sectional curves and the mass stopping power obtained from the X-PMSP program. Furthermore, based on the obtained results, the appropriate reaction processes for the production of ^(82)Sr and ^(68)Ge isotopes on Rb-85, Ga-69, and Ga-71 targets are discussed.
基金Supported by the National Natural Science Foundation of China(No.51577124)Tianjin Research Program of Application Foundation and Advanced Technology(No.15JCZDJC32100)
文摘In this paper, a design method for ocean wave permanent magnet synchronous generator(PMSG)is proposed with new performance criteria to obtain better output performance at the cost of less permanent magnet material. Besides, a simple equivalent analytical geometry method is put forward to calculate the sizes of permanent magnets. Based on geometric and electromagnetic models, four types of rotor structures are compared, i.e., embedded, tangential, tile surface mount and convex surface mount structures. The designs and comparisons of machine are performed with the same permanent magnet volume. Moreover, the influences of mechanical pole-arc coefficient of tile surface mount PMSG on electrical efficiency, output power, material corrosion, core loss, and torque ripple are investigated. Finite-element analysis method is applied to verify the results using Ansoft/Maxwell.
文摘A data acquisition system for testing gas sensor array response to multi-gas is presented.The testing system is based on the character of the gas response of metal oxide semiconductor gas sensor array.The data acquisition is realized automatically through the real time controlling of the data acquisition card PCI1711.This system is highly attractive for electronic nose,which is a powerful tool for the discrimination of gases.
文摘All modes of operation of a two-capacitor generator based on overflow of the charge accumulated in capacitors through the load resistance between two capacitors with antiphase modulated capacitances by means of in-plane or out-of-plane shift of the electrode plates under action of a mechanical force are analyzed paying the especial attention to fabrication of the generators with small sizes. Numerical solutions for all the modes are obtained, and they are found to be universal. Analytical estimates of the maximum power of the generator as a function of the capacitances modulation factor are derived. Experimental investigations of a two-capacitor rotational electric generator show that its characteristics are consistent with the analysis performed and that this analysis can be used to describe all specific features of operation of particular generators. Applications of the devices in micro-design for feeding the remote sensors are discussed.
文摘This paper studied the direct-drive permanent magnet synchronous machine (permanent magnet synchronous generator, PMSG) Chopper optimal topology and resistance value. Compared the different Chopper circuit low voltage ride-through capability in the same grid fault conditions in simulation. This paper computes the dump resistance ceiling according to the power electronic devices and over-current capability. Obtaining the dump resistance low limit according to the temperature resistance allows, and calculating the optimal value by drop voltage in the DC-Bus during the fault. The feasibility of the proposed algorithm is verified by simulation results.
基金Project(2011DFA62240) supported by the International Scientific and Technological Cooperation Projects,ChinaProject(019945-SES6) supported by the European Union(EU)6th Framework Program UP-WIND Project,Denmark
文摘An analytic electromagnetic calculation method for doubly fed induction generator(DFIG) in wind turbine system was presented. Based on the operation principles, steady state equivalent circuit and basic equations of DFIG, the modeling for electromagnetic calculation of DFIG was proposed. The electromagnetic calculation of DFIG was divided into three steps: the magnetic flux calculation, parameters derivation and performance checks. For each step, the detailed numeric calculation formulas were all derived. Combining the calculation formulas, the whole electromagnetic calculation procedure was established, which consisted of three iterative calculation loops, including magnetic saturation coefficient, electromotive force and total output power. All of the electromagnetic and performance data of DIFG can be calculated conveniently by the established calculation procedure, which can be used to evaluate the new designed machine. A 1.5 MW DFIG designed by the proposed procedure was built, for which the whole type tests including no-load test, load test and temperature rising test were carried out. The test results have shown that the DFIG satisfies technical requirements and the test data fit well with the calculation results which prove the correctness of the presented calculation method.
基金This work was supported by the National Natural Science Foundation of China (No.G60474001) the Research Fund for Doctoral Program of Chinese Higher Education (No.G20040422059).
文摘Based on Hamiltonian formulation, this paper proposes a design approach to nonlinear feedback excitation control of synchronous generators with steam valve control, disturbances and unknown parameters. It is shown that the dynamics of the synchronous generators can be expressed as a dissipative Hamiltonian system, based on which an adaptive H-infinity controller is then designed for the systems by using the structure properties of dissipative Hamiltonian systems. Simulations show that the controller obtained in this paper is very effective.
基金This study was supported by the third sub-project of the national key research project in the 9thFive-Year Plan: Study on the
文摘By adopting various stochastic weather generators, different research groups in their recent studies have realized the importance of the effects of climatic variability on crop growth and development. The conventional assessments derived climate change scenarios from General Circulation Models (GCMs) experiments, however, are incapable of helping to understand this importance. The particular interest here is to review the general methodological scheme to incorporate stochastic weather generator into climate impact studies and the specific approaches in our studies, and put forward uncertainties that still exist. A variety of approaches have been taken to develop the parameterization program and stochastic experiment, and adjust the parameters of atypical stochastic weather generator called WGEN. Usually, the changes in monthly means and variances of weather variables between controlled and changed climate are used to perturb the parameters to generate the intended daily climate scenarios. We establish a parameterization program and methods for stochastic experiment of WGEN in the light of outputs of short-term climate prediction models, and evaluate its simulations on both temporal and spatial scales. Also, we manipulated parameters in relation to the changes in precipitation to produce the intended types and qualitative magnitudes of climatic variability. These adjustments yield various changes in climatic variability for sensitivity analyses. The impacts of changes in climatic variability on maize growth, final yield, and agro-climatic resources in Northeast China are assessed and presented as the case studies through the above methods. However, this corporation is still equivocal due to deficiencies of the generator and unsophisticated manipulation of parameters. To detect and simulate the changes in climatic variability is one of the indispensable ways to reduce the uncertainties in this aspect.
文摘The chaos-based feedforward output functions for combining keystream generators are proposed according to chaotic dynamic theory. The generated binary signals are independently and identically distributed, and have predictable periods. All experiments correspond to the theoretical prediction very well.
基金financially supported by the National Natural Science Foundation of China(Nos.51173134 and 51573139)Fundamental Research Funds for the Central Universities and the Open Measuring Fund for Large Instrument and Equipment(No.0002015033)of Tongji University
文摘A series of D-π-A type sulfonium salt photoacid generators with different π-conjugated structures, such as triphenyl, phenylstilbene, styryl-biphenyl, and stilbene, were designed to determine the effect of molecular structures on the photochemical and photophysical properties. The mechanisms of photochemical generation of H＋ were studied by UV-Vis spectroscopy, theoretical calculations, and fluorescence spectroscopy. It is found that the frontier orbits determine the absorption, the molar extinction coefficients, and the quantum yields of photoacid generation. Triphenyl systems connected with sulfonium are beneficial to increase the quantum yields of acid generation. The photoreactivity of four sulfonium salts was further evaluated through the polymerizations of various epoxide monomers at different irradiation wavelengths （365- 425 nm） by using the real-time infrared spectroscopy with light-emitting diodes. The high quantum yields for acid generation （ФH＋ = -0.32 to 0.58） and the high molar extinction coefficients （ε = -23500 L.mol-1.cm-1 to 31000 L.mol-1.cm-1） of the sulfonium salts lead to high conversion rates （over 50%-80%）. Hence, these photoinitiators exhibit potential for the photocuring applications.
基金financially supported by the Shenzhen Sci-ence and Technology Program(No.KQTD20200820113045081)the State Key Laboratory of Advanced Welding and Join-ing,Harbin Institute of Technology+7 种基金the financial support from the National Natural Science Foun-dation of China(Nos.52172194,51971081)the Natural Sci-ence Foundation for Distinguished Young Scholars of Guangdong Province of China(No.2020B1515020023)the Natural Science Foundation for Distinguished Young Scholars of Shenzhen(No.RCJC20210609103733073)the Key Project of Shenzhen Funda-mental Research Projects(No.JCYJ20200109113418655)the financial support from the National Natural Sci-ence Foundation of China(No.51871081)the financial support from the National Natural Science Foundation of China(No.52101248)Shenzhen fundamental research projects(No.JCYJ20210324132808020)the start-up funding of Shenzhen,and the start-up funding of Harbin Institute of Technology(Shen-zhen).
文摘To satisfy the requirements of practical applications,thermoelectric generators should be highly efficient and mechanically robust.Recently,progress in designing high-performance thermoelectric generators has been made.However,the mechanical properties of thermoelectric generators are still unsatisfactory.In this review,studies on the mechanical properties of thermoelectric generators are summarized.The me-chanical properties of bulk thermoelectric generators will be first discussed.In this section,the mechan-ical properties of thermoelectric materials and the strategies for improving their mechanical properties are emphasized.Since the device’s failure usually occurs at the interface between the thermoelectric ma-terials and electrode,the joint strength of electrodes and thermoelectric materials will be overviewed.After that,the mechanical properties of the inorganic thin-film thermoelectric devices will be discussed.Since the figure of merit for the flexibility of thermoelectric materials depends on the film thickness,elastic modulus,and yield strength,the synthesis methods of thin-film thermoelectric materials will be reviewed.Finally,this review will be concluded with a discussion on flexible organic thermoelectric de-vices and flexible devices using bulk legs.
基金financially supported by the National Key Research and Development Program of China (No.2017YFC0805204)the National Natural Science Foundation of China (Nos.51504017 and 51874015)
文摘Chemical oxygen generators(COGs)have been used worldwide in confined spaces as an emergency oxygen supply technology,mainly because they are independent and have a long shelf life.However,a number of challenges related to COGs remain unsolved,and a literature review of the current state of the technology is needed.First,the present article summarizes the basic information and applications of COGs,including their oxygen production mechanism,components,forming technology,and ignition system.Four current challenges encountered in applying COGs are discussed,along with the strategies adopted thus far to solve these problems,as found in the published literature.The literature survey reveals that,although much effort has been devoted to controlling the oxygen production rate and the heat output of COGs,the mechanism of producing toxic gases remains unclear and a reliable and safe ignition system has not been fully developed.Finally,future opportunities in the development of COGs are briefly listed.
文摘With the rapid increase of wind farms,the grid code needs to be improved to meet the requirement of wind farms and enhance grid stability.Doubly-fed induction generators are largely used in wind turbines,but they are very sensitive to grid disturbances.The voltage swell can be caused by switching on capacitor banks or switching off large loads,which may result in the reversal of the power flow in the grid convertor;the current may flow from the grid into the DC link,which may step up DC voltage,and result in large faults of rotor currents and instantaneous power oscillation.The grid reactive compensation devices can not have the automatic swithing function after the low voltage fault,which will result in local reactive power surplus,so some wind power generators will retreat from the grid under high voltage protection.
基金supported by National Natural Science Foundation of China(No.51903099 and 51991353)100 Talents Program of Hubei Provincial Government,Huazhong University of Science and Technology(No.3004013134 and 2021XXJS036)+1 种基金the Innovation and Talent Recruitment Base of New Energy Chemistry and Device(No.B21003)the Open Research Fund of State Key Laboratory of Polymer Physics and Chemistry,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences.
文摘Solar evaporation is recognized as a prospective technique to produce freshwater from non-drinkable water using inexhaustible solar energy.However,it remains a challenge to fabricate low-cost solar evaporators with obviously reduced water evaporation enthalpy to achieve high evaporation rates.Herein,N,O dual-doped carbon foam(NCF)is fabricated from the lowtemperature carbonization of poly(ethylene terephthalate)(PET)waste by melamine/molten salts at 340℃.During carbonization,melamine reacts with carboxylic acids of PET degradation products to yield a crosslinking network,and then molten salts catalyze the decarboxylation and dehydration to construct a stable framework.Owing to rich N,O-containing groups,3D interconnected pores,super-hydrophilicity,and ultra-low thermal conductivity(0.0599 W m^(−1) K^(−1)),NCF not only achieves high light absorbance(ca.99%)and solar-to-thermal conversion,but also promotes the formation of water cluster to reduce water evaporation enthalpy by ca.37%.Consequently,NCF exhibits a high evaporation rate(2.4 kg m^(−2) h^(−1)),surpassing the-state-of-the-art solar evaporators,and presents good antiacid/basic abilities,long-term salt-resistance,and self-cleaning ability.Importantly,a large-scale NCF-based outdoor solar desalination device is developed to produce freshwater.The daily freshwater production amount per unit area(6.3 kg)meets the two adults’daily water consumption.The trash-to-treasure strategy will give impetus to the development of low-cost,advanced solar evaporators from waste plastics for addressing the global freshwater shortage.
