In the experiment, the brown rice whose moisture content was 12.5% was used as raw material. The brown rice was grouped, then moisturized differently and milled. While milling, the energy consumption, the rate of brok...In the experiment, the brown rice whose moisture content was 12.5% was used as raw material. The brown rice was grouped, then moisturized differently and milled. While milling, the energy consumption, the rate of broken rice and the crack rate were tested. It is confirmed that the stress crack owing to the moisture added to the brown rice can be avoided when the moisture amount added once is limited to no more than 1.5%. It is also proved that the energy consumption can be reduced, the yielding rate of rice can be increased and that the quality of rice can be improved.展开更多
This paper presents a method to acquire runtime distribution ratio of building air conditioning system under part load condition (part load coefficient of system) through practical energy consumption data. By utilizin...This paper presents a method to acquire runtime distribution ratio of building air conditioning system under part load condition (part load coefficient of system) through practical energy consumption data. By utilizing monthly energy consumption data of the entire year as the analysis object,this paper identifies data distribution,verifies distribution characteristics and analyzes distribution probability density for the issue of running time distribution ratio of air conditioning system in part load zones in the whole operation period,thus providing a basic calculation basis for an overall analysis of energy efficiency of air conditioning system. In view of the general survey of public building energy consumption carried by the government of Chongqing,this paper takes the governmental office building as an example,the part load ratio coefficient corresponding to practical running of air conditioning system of governmental office building in Chongqing is obtained by utilizing the above probability analysis and the solving method of probability density function. By utilizing the ratio coefficient obtained using this method,the part load coefficient with any running ratio of air conditioning system can be obtained according to the requirement of analysis,which can be used in any load ratio for analyzing running energy efficiency of air conditioning system.展开更多
A sewage heat pump system and its application based on a project in Chongqing,China,were discussed. Based on the sewage conditions,a feasibility analysis of the sewage heat pump air conditioning system was conducted. ...A sewage heat pump system and its application based on a project in Chongqing,China,were discussed. Based on the sewage conditions,a feasibility analysis of the sewage heat pump air conditioning system was conducted. The theoretical and quantitative calculations indicate that sewage flux in the city sewage main pipe in the project can satisfy heat exchange requirements,and taking water from the pipes has relatively small influence on the pipe net in summer and winter. The sewage heat pump air-conditioning system can save 21.5% operating cost in one year,which is energy efficient and environmentally friendly.展开更多
In order to investigate the bacteria and fungi aerosol characteristic distribution in HVAC-system and its components at Shaanxi History Museum.Measurements were performed to probe the bacteria and fungi aerosol in HVA...In order to investigate the bacteria and fungi aerosol characteristic distribution in HVAC-system and its components at Shaanxi History Museum.Measurements were performed to probe the bacteria and fungi aerosol in HVAC systems,located at Xi'an city,China.The results showed that there was fungi growth inside the ventilation ducts,fungi contamination was worse than bacteria,and both of them were distributed into occupied space with the air supply ducts.The dominating genera of fungi was found to be Penicillium spp.and Aspergillus spp.,which was respectively 46.1% and 20.7% in settling fungi,and the dominating genera of fungi in dust were Cladosporium spp.and Penicillium spp.,which was 41.8% and 30.1% respectively.It suggests that available measures to improve and control the performance of HVAC-systems such as the maintenance,management and cleaning should be taken to prevent this pollution and to develop strategies to keep this pollution away.展开更多
The operating theory of an evaporative condenser was expatiated.The difference between an evaporative condensing refrigeration system and a general refrigeration system was analyzed.Compared with the air-cooled and th...The operating theory of an evaporative condenser was expatiated.The difference between an evaporative condensing refrigeration system and a general refrigeration system was analyzed.Compared with the air-cooled and the water-cooled,the virtues of energy-conservation and water-conservation of evaporative condensers were analyzed.Some questions existing in the application of evaporative condensers were pointed out,the corresponding solving methods were analyzed accordingly,and the development trend of evaporative condensing technique in mechanical refrigeration system field and the applied foreground of evaporative condensers in comfortable air conditioning were prospected.展开更多
In order to realize the real-time and precise test for a weapon system of a certain type of fighter,a signal classification method according to attributes is proposed,common input channels for multiple signals are con...In order to realize the real-time and precise test for a weapon system of a certain type of fighter,a signal classification method according to attributes is proposed,common input channels for multiple signals are configured optimally,and a test adapter and an adaptive signal conditioning module is designed. The hardware of conditioning module can be configured flexibly and the programmable test range can be adjusted owing to programmable multiplexer. An FPGA adaptive filter is designed by the calculated filter coefficient vectors with LMS method to solve the problem of parallel test of fighter weapon system in electromagnetic interference environment. The adaptive signal conditioning technology is characterized by high efficiency,precision and integration. Its application makes the test system successful to conduct real-time and parallel test for a weapon system,which is developed based on VXI bus and virtual-instrument technology.展开更多
ZnO is a highly significant II-VI semiconductor known for its excellent optoelectronic properties,making it widely applicable and promising for use in light-emitting devices,solar cells,lasers,and photodetectors.The m...ZnO is a highly significant II-VI semiconductor known for its excellent optoelectronic properties,making it widely applicable and promising for use in light-emitting devices,solar cells,lasers,and photodetectors.The methods for preparing ZnO are diverse,and among them,the hydrothermal method is favored for its simplicity,ease of operation,and low cost,making it an optimal choice for ZnO single-crystal growth.Most studies investigating the effects of different hydrothermal experimental parameters on the morphology and performance of ZnO nano-materials typically focus on only 2—3 variable parameters,with few examining the impact of all possible experimental parameter changes on ZnO nano-mate-rials.The principles of the hydrothermal method and its advantages in nano-material preparation were briefly introduced in this article.The detailed discussion on the influence of various experimental parameters on the preparation of ZnO nano-materials was provided,which including reaction materials,Zn^(2+)/OH^(-)ratio,reaction time and temperature,additives,experimental equipment,and annealing conditions.The review co-vers how different experimental parameters affect the morphology and performance of the materials,as well as how different rare earth doping elements influence the performance of ZnO nano-materials.It is hoped that this work will contribute to future research on the hydrothermal synthesis of nano-materials.展开更多
In this study,we examine the problem of sliced inverse regression(SIR),a widely used method for sufficient dimension reduction(SDR).It was designed to find reduced-dimensional versions of multivariate predictors by re...In this study,we examine the problem of sliced inverse regression(SIR),a widely used method for sufficient dimension reduction(SDR).It was designed to find reduced-dimensional versions of multivariate predictors by replacing them with a minimally adequate collection of their linear combinations without loss of information.Recently,regularization methods have been proposed in SIR to incorporate a sparse structure of predictors for better interpretability.However,existing methods consider convex relaxation to bypass the sparsity constraint,which may not lead to the best subset,and particularly tends to include irrelevant variables when predictors are correlated.In this study,we approach sparse SIR as a nonconvex optimization problem and directly tackle the sparsity constraint by establishing the optimal conditions and iteratively solving them by means of the splicing technique.Without employing convex relaxation on the sparsity constraint and the orthogonal constraint,our algorithm exhibits superior empirical merits,as evidenced by extensive numerical studies.Computationally,our algorithm is much faster than the relaxed approach for the natural sparse SIR estimator.Statistically,our algorithm surpasses existing methods in terms of accuracy for central subspace estimation and best subset selection and sustains high performance even with correlated predictors.展开更多
In this paper,we propose a three-term conjugate gradient method for solving unconstrained optimization problems based on the Hestenes-Stiefel(HS)conjugate gradient method and Polak-Ribiere-Polyak(PRP)conjugate gradien...In this paper,we propose a three-term conjugate gradient method for solving unconstrained optimization problems based on the Hestenes-Stiefel(HS)conjugate gradient method and Polak-Ribiere-Polyak(PRP)conjugate gradient method.Under the condition of standard Wolfe line search,the proposed search direction is the descent direction.For general nonlinear functions,the method is globally convergent.Finally,numerical results show that the proposed method is efficient.展开更多
A Receiver Operating Characteristic(ROC)analysis of a power is important and useful in clinical trials.A Classical Conditional Power(CCP)is a probability of a classical rejection region given values of true treatment ...A Receiver Operating Characteristic(ROC)analysis of a power is important and useful in clinical trials.A Classical Conditional Power(CCP)is a probability of a classical rejection region given values of true treatment effect and interim result.For hypotheses and reversed hypotheses under normal models,we obtain analytical expressions of the ROC curves of the CCP,find optimal ROC curves of the CCP,investigate the superiority of the ROC curves of the CCP,calculate critical values of the False Positive Rate(FPR),True Positive Rate(TPR),and cutoff of the optimal CCP,and give go/no go decisions at the interim of the optimal CCP.In addition,extensive numerical experiments are carried out to exemplify our theoretical results.Finally,a real data example is performed to illustrate the go/no go decisions of the optimal CCP.展开更多
Federated learning(FL)is a distributed machine learning paradigm for edge cloud computing.FL can facilitate data-driven decision-making in tactical scenarios,effectively addressing both data volume and infrastructure ...Federated learning(FL)is a distributed machine learning paradigm for edge cloud computing.FL can facilitate data-driven decision-making in tactical scenarios,effectively addressing both data volume and infrastructure challenges in edge environments.However,the diversity of clients in edge cloud computing presents significant challenges for FL.Personalized federated learning(pFL)received considerable attention in recent years.One example of pFL involves exploiting the global and local information in the local model.Current pFL algorithms experience limitations such as slow convergence speed,catastrophic forgetting,and poor performance in complex tasks,which still have significant shortcomings compared to the centralized learning.To achieve high pFL performance,we propose FedCLCC:Federated Contrastive Learning and Conditional Computing.The core of FedCLCC is the use of contrastive learning and conditional computing.Contrastive learning determines the feature representation similarity to adjust the local model.Conditional computing separates the global and local information and feeds it to their corresponding heads for global and local handling.Our comprehensive experiments demonstrate that FedCLCC outperforms other state-of-the-art FL algorithms.展开更多
Recently,foamed polymers have been widely used in the repair of underground engineering disasters by grouting(trenchless technology)due to controllable gelation time and self-expansion.However,the grouting process bec...Recently,foamed polymers have been widely used in the repair of underground engineering disasters by grouting(trenchless technology)due to controllable gelation time and self-expansion.However,the grouting process becomes more complicated due to the complex geological conditions and the self-expansion of slurry.Therefore,this paper adopts a self-made visual experimental device with peripheral pressure and water plugging rate(WPR)monitoring functions to study the influence of main influencing parameters(particle size distribution,grouting amount and dynamic water pump pressure(DWPP))on the spatiotemporal distribution of slurry WPR and diffusion dynamic response(peripheral pressure).The results show that:When grouting amount is 563 g and DWPP is 0.013 MPa,the expansion force of the slurry in the diffusion process is dominant and can significantly change the local sand and gravel skeleton structure.When grouting amount is 563 g,DWPP is 0.013 MPa,and particle size distribution type isⅢ,the flow time of the polymer is shortened,the pores of the gravel are rapidly blocked.Then,the peripheral pressure decreases rapidly with the increase of the distance,and the time to reach the inflection point WPR is shortened.The instantaneous blockage of the pores leads to the delayed transmission of flow field blockage information.展开更多
Efficient tool condition monitoring techniques help to realize intelligent management of tool life and reduce tool usage costs.In this paper,the influence of different wear degrees of ball-end milling cutters on the t...Efficient tool condition monitoring techniques help to realize intelligent management of tool life and reduce tool usage costs.In this paper,the influence of different wear degrees of ball-end milling cutters on the texture shape of machining tool marks is investigated,and a method is proposed for predicting the wear state(including the position and degree of tool wear)of ball-end milling cutters based on entropy measurement of tool mark texture images.Firstly,data samples are prepared through wear experiments,and the change law of the tool mark texture shape with the tool wear state is analyzed.Then,a two-dimensional sample entropy algorithm is developed to quantify the texture morphology.Finally,the processing parameters and tool attitude are integrated into the prediction process to predict the wear value and wear position of the ball end milling cutter.After testing,the correlation between the predicted value and the standard value of the proposed tool condition monitoring method reaches 95.32%,and the accuracy reaches 82.73%,indicating that the proposed method meets the requirement of tool condition monitoring.展开更多
This study proposes an alternative calculation mode for stresses on the slip surface(SS).The calculation of the normal stress(NS)on the SS involves examining its composition and expanding its unknown using the Taylor ...This study proposes an alternative calculation mode for stresses on the slip surface(SS).The calculation of the normal stress(NS)on the SS involves examining its composition and expanding its unknown using the Taylor series.This expansion enables the reasonable construction of a function describing the NS on the SS.Additionally,by directly incorporating the nonlinear Generalized Hoke-Brown(GHB)strength criterion and utilizing the slope factor of safety(FOS)definition,a function of the shear stress on the SS is derived.This function considers the mutual feedback mechanism between the NS and strength parameters of the SS.The stress constraints conditions are then introduced at both ends of the SS based on the spatial stress relation of one point.Determining the slope FOS and stress solution for the SS involves considering the mechanical equilibrium conditions and the stress constraint conditions satisfied by the sliding body.The proposed approach successfully simulates the tension-shear stress zone near the slope top and provides an intuitive description of the concentration effect of compression-shear stress of the SS near the slope toe.Furthermore,compared to other methods,the present method demonstrates superior processing capabilities for the embedded nonlinear GHB strength criterion.展开更多
Architecture framework has become an effective method recently to describe the system of systems(SoS)architecture,such as the United States(US)Department of Defense Architecture Framework Version 2.0(DoDAF2.0).As a vi...Architecture framework has become an effective method recently to describe the system of systems(SoS)architecture,such as the United States(US)Department of Defense Architecture Framework Version 2.0(DoDAF2.0).As a viewpoint in DoDAF2.0,the operational viewpoint(OV)describes operational activities,nodes,and resource flows.The OV models are important for SoS architecture development.However,as the SoS complexity increases,constructing OV models with traditional methods exposes shortcomings,such as inefficient data collection and low modeling standards.Therefore,we propose an intelligent modeling method for five OV models,including operational resource flow OV-2,organizational relationships OV-4,operational activity hierarchy OV-5a,operational activities model OV-5b,and operational activity sequences OV-6c.The main idea of the method is to extract OV architecture data from text and generate interoperable OV models.First,we construct the OV meta model based on the DoDAF2.0 meta model(DM2).Second,OV architecture named entities is recognized from text based on the bidirectional long short-term memory and conditional random field(BiLSTM-CRF)model.And OV architecture relationships are collected with relationship extraction rules.Finally,we define the generation rules for OV models and develop an OV modeling tool.We use unmanned surface vehicles(USV)swarm target defense SoS architecture as a case to verify the feasibility and effectiveness of the intelligent modeling method.展开更多
Solder joint,crucial component in electronic systems,face significant challenges when exposed to extreme conditions during applications.The solder joint reliability involving microstructure and mechanical properties w...Solder joint,crucial component in electronic systems,face significant challenges when exposed to extreme conditions during applications.The solder joint reliability involving microstructure and mechanical properties will be affected by extreme conditions.Understanding the behaviour of solder joints under extreme conditions is vital to determine the durability and reliability of solder joint.This review paper aims to comprehensively explore the underlying failure mechanism affecting solder joint reliability under extreme conditions.This study covers an in-depth analysis of effect extreme temperature,mechanical stress,and radiation conditions towards solder joint.Impact of each condition to the microstructure including solder matrix and intermetallic compound layer,and mechanical properties such as fatigue,shear strength,creep,and hardness was thoroughly discussed.The failure mechanisms were illustrated in graphical diagrams to ensure clarity and understanding.Furthermore,the paper highlighted mitigation strategies that enhancing solder joint reliability under challenging operating conditions.The findings offer valuable guidance for researchers,engineers,and practitioners involved in electronics,engineering,and related fields,fostering advancements in solder joint reliability and performance.展开更多
Structural health monitoring is widely utilized in outdoor environments,especially under harsh conditions,which can introduce noise into the monitoring system.Therefore,designing an effective denoising strategy to enh...Structural health monitoring is widely utilized in outdoor environments,especially under harsh conditions,which can introduce noise into the monitoring system.Therefore,designing an effective denoising strategy to enhance the performance of guided wave damage detection in noisy environments is crucial.This paper introduces a local temporal principal component analysis(PCA)reconstruction approach for denoising guided waves prior to implementing unsupervised damage detection,achieved through novel autoencoder-based reconstruction.Experimental results demonstrate that the proposed denoising method significantly enhances damage detection performance when guided waves are contaminated by noise,with SNR values ranging from 10 to-5 dB.Following the implementation of the proposed denoising approach,the AUC score can elevate from 0.65 to 0.96 when dealing with guided waves corrputed by noise at a level of-5 dB.Additionally,the paper provides guidance on selecting the appropriate number of components used in the denoising PCA reconstruction,aiding in the optimization of the damage detection in noisy conditions.展开更多
High purity and ultrafine DAAF(u-DAAF)is an emerging insensitive charge in initiators.Although there are many ways to obtain u-DAAF,developing a preparation method with stable operation,accurate control,good quality c...High purity and ultrafine DAAF(u-DAAF)is an emerging insensitive charge in initiators.Although there are many ways to obtain u-DAAF,developing a preparation method with stable operation,accurate control,good quality consistency,equipment miniaturization,and minimum manpower is an inevitable requirement to adapt to the current social technology development trend.Here reported is the microfluidic preparation of u-DAAF with tunable particle size by a passive swirling microreactor.Under the guidance of recrystallization growth kinetics and mixing behavior of fluids in the swirling microreactor,the key parameters(liquid flow rate,explosive concentration and crystallization temperature)were screened and optimized through screening experiments.Under the condition that no surfactant is added and only experimental parameters are controlled,the particle size of recrystallized DAAF can be adjusted from 98 nm to 785 nm,and the corresponding specific surface area is 8.45 m^(2)·g^(-1)to 1.33 m^(2)·g^(-1).In addition,the preparation method has good batch stability,high yield(90.8%-92.6%)and high purity(99.0%-99.4%),indicating a high practical application potential.Electric explosion derived flyer initiation tests demonstrate that the u-DAAF shows an initiation sensitivity much lower than that of the raw DAAF,and comparable to that of the refined DAAF by conventional spraying crystallization method.This study provides an efficient method to fabricate u-DAAF with narrow particle size distribution and high reproducibility as well as a theoretical reference for fabrication of other ultrafine explosives.展开更多
Finding sustainable energy resources is essential to face the increasing energy demand.Trees are an important part of ancient architecture but are becoming rare in urban areas.Trees can control and tune the pedestrian...Finding sustainable energy resources is essential to face the increasing energy demand.Trees are an important part of ancient architecture but are becoming rare in urban areas.Trees can control and tune the pedestrian-level wind velocity and thermal condition.In this study,a numerical investigation is employed to assess the role of trees planted in the windward direction of the building complex on the thermal and pedestrian wind velocity conditions around/inside a pre-education building located in the center of the complex.Compared to the previous studies(which considered only outside buildings),this work considers the effects of trees on microclimate change both inside/outside buildings.Effects of different parameters including the leaf area density and number of trees,number of rows,far-field velocity magnitude,and thermal condition around the main building are assessed.The results show that the flow velocity in the spacing between the first-row buildings is reduced by 30%-40% when the one-row trees with 2 m height are planted 15 m farther than the buildings.Furthermore,two rows of trees are more effective in higher velocities and reduce the maximum velocity by about 50%.The investigation shows that trees also could reduce the temperature by about 1℃around the building.展开更多
基金Tenth Eive-Year Plan of the Committee of the Scientific Tech. of Heilongjiang Province (GB02B4040-1)Heilongjiang Education Bureau (10511012)
文摘In the experiment, the brown rice whose moisture content was 12.5% was used as raw material. The brown rice was grouped, then moisturized differently and milled. While milling, the energy consumption, the rate of broken rice and the crack rate were tested. It is confirmed that the stress crack owing to the moisture added to the brown rice can be avoided when the moisture amount added once is limited to no more than 1.5%. It is also proved that the energy consumption can be reduced, the yielding rate of rice can be increased and that the quality of rice can be improved.
基金Project(50838009) supported by the National Natural Science Foundation of ChinaProjects(2006BAJ02A09,2006BAJ02A13-4) supported by the National Key Technologies R & D Program of ChinaProject(CSTC,2008AB7110) supported by the Key Technologies R & D Programme of Chongqing,China
文摘This paper presents a method to acquire runtime distribution ratio of building air conditioning system under part load condition (part load coefficient of system) through practical energy consumption data. By utilizing monthly energy consumption data of the entire year as the analysis object,this paper identifies data distribution,verifies distribution characteristics and analyzes distribution probability density for the issue of running time distribution ratio of air conditioning system in part load zones in the whole operation period,thus providing a basic calculation basis for an overall analysis of energy efficiency of air conditioning system. In view of the general survey of public building energy consumption carried by the government of Chongqing,this paper takes the governmental office building as an example,the part load ratio coefficient corresponding to practical running of air conditioning system of governmental office building in Chongqing is obtained by utilizing the above probability analysis and the solving method of probability density function. By utilizing the ratio coefficient obtained using this method,the part load coefficient with any running ratio of air conditioning system can be obtained according to the requirement of analysis,which can be used in any load ratio for analyzing running energy efficiency of air conditioning system.
基金Project(50838009) supported by the National Natural Science Foundation of ChinaProjects(2006BAJ02A09+1 种基金2006BAJ02A13-4) supported by the National Key Technologies R&D ProgramProject(2006BAJ01A06-3) supported by the Key R & D Program during the Eleventh Five-Year Plan Period,China
文摘A sewage heat pump system and its application based on a project in Chongqing,China,were discussed. Based on the sewage conditions,a feasibility analysis of the sewage heat pump air conditioning system was conducted. The theoretical and quantitative calculations indicate that sewage flux in the city sewage main pipe in the project can satisfy heat exchange requirements,and taking water from the pipes has relatively small influence on the pipe net in summer and winter. The sewage heat pump air-conditioning system can save 21.5% operating cost in one year,which is energy efficient and environmentally friendly.
基金Supported by the National Natural Science Foundation of China(50878177)the Rearch Fund for the Doctoral Program of Higher Education
文摘In order to investigate the bacteria and fungi aerosol characteristic distribution in HVAC-system and its components at Shaanxi History Museum.Measurements were performed to probe the bacteria and fungi aerosol in HVAC systems,located at Xi'an city,China.The results showed that there was fungi growth inside the ventilation ducts,fungi contamination was worse than bacteria,and both of them were distributed into occupied space with the air supply ducts.The dominating genera of fungi was found to be Penicillium spp.and Aspergillus spp.,which was respectively 46.1% and 20.7% in settling fungi,and the dominating genera of fungi in dust were Cladosporium spp.and Penicillium spp.,which was 41.8% and 30.1% respectively.It suggests that available measures to improve and control the performance of HVAC-systems such as the maintenance,management and cleaning should be taken to prevent this pollution and to develop strategies to keep this pollution away.
基金Supported by the combined project of the Science and Technology Ministry of Guangdong province and the Science and Tech-nology Ministry of Guangzhou city(2007A04020004,2007C13G0161)
文摘The operating theory of an evaporative condenser was expatiated.The difference between an evaporative condensing refrigeration system and a general refrigeration system was analyzed.Compared with the air-cooled and the water-cooled,the virtues of energy-conservation and water-conservation of evaporative condensers were analyzed.Some questions existing in the application of evaporative condensers were pointed out,the corresponding solving methods were analyzed accordingly,and the development trend of evaporative condensing technique in mechanical refrigeration system field and the applied foreground of evaporative condensers in comfortable air conditioning were prospected.
基金Sponsored by the Key Equipment Research Project of Air Force of China (KJZ06119)
文摘In order to realize the real-time and precise test for a weapon system of a certain type of fighter,a signal classification method according to attributes is proposed,common input channels for multiple signals are configured optimally,and a test adapter and an adaptive signal conditioning module is designed. The hardware of conditioning module can be configured flexibly and the programmable test range can be adjusted owing to programmable multiplexer. An FPGA adaptive filter is designed by the calculated filter coefficient vectors with LMS method to solve the problem of parallel test of fighter weapon system in electromagnetic interference environment. The adaptive signal conditioning technology is characterized by high efficiency,precision and integration. Its application makes the test system successful to conduct real-time and parallel test for a weapon system,which is developed based on VXI bus and virtual-instrument technology.
文摘ZnO is a highly significant II-VI semiconductor known for its excellent optoelectronic properties,making it widely applicable and promising for use in light-emitting devices,solar cells,lasers,and photodetectors.The methods for preparing ZnO are diverse,and among them,the hydrothermal method is favored for its simplicity,ease of operation,and low cost,making it an optimal choice for ZnO single-crystal growth.Most studies investigating the effects of different hydrothermal experimental parameters on the morphology and performance of ZnO nano-materials typically focus on only 2—3 variable parameters,with few examining the impact of all possible experimental parameter changes on ZnO nano-mate-rials.The principles of the hydrothermal method and its advantages in nano-material preparation were briefly introduced in this article.The detailed discussion on the influence of various experimental parameters on the preparation of ZnO nano-materials was provided,which including reaction materials,Zn^(2+)/OH^(-)ratio,reaction time and temperature,additives,experimental equipment,and annealing conditions.The review co-vers how different experimental parameters affect the morphology and performance of the materials,as well as how different rare earth doping elements influence the performance of ZnO nano-materials.It is hoped that this work will contribute to future research on the hydrothermal synthesis of nano-materials.
文摘In this study,we examine the problem of sliced inverse regression(SIR),a widely used method for sufficient dimension reduction(SDR).It was designed to find reduced-dimensional versions of multivariate predictors by replacing them with a minimally adequate collection of their linear combinations without loss of information.Recently,regularization methods have been proposed in SIR to incorporate a sparse structure of predictors for better interpretability.However,existing methods consider convex relaxation to bypass the sparsity constraint,which may not lead to the best subset,and particularly tends to include irrelevant variables when predictors are correlated.In this study,we approach sparse SIR as a nonconvex optimization problem and directly tackle the sparsity constraint by establishing the optimal conditions and iteratively solving them by means of the splicing technique.Without employing convex relaxation on the sparsity constraint and the orthogonal constraint,our algorithm exhibits superior empirical merits,as evidenced by extensive numerical studies.Computationally,our algorithm is much faster than the relaxed approach for the natural sparse SIR estimator.Statistically,our algorithm surpasses existing methods in terms of accuracy for central subspace estimation and best subset selection and sustains high performance even with correlated predictors.
基金Supported by the Science and Technology Project of Guangxi(Guike AD23023002)。
文摘In this paper,we propose a three-term conjugate gradient method for solving unconstrained optimization problems based on the Hestenes-Stiefel(HS)conjugate gradient method and Polak-Ribiere-Polyak(PRP)conjugate gradient method.Under the condition of standard Wolfe line search,the proposed search direction is the descent direction.For general nonlinear functions,the method is globally convergent.Finally,numerical results show that the proposed method is efficient.
基金supported by the National Social Science Fund of China(Grand No.21XTJ001).
文摘A Receiver Operating Characteristic(ROC)analysis of a power is important and useful in clinical trials.A Classical Conditional Power(CCP)is a probability of a classical rejection region given values of true treatment effect and interim result.For hypotheses and reversed hypotheses under normal models,we obtain analytical expressions of the ROC curves of the CCP,find optimal ROC curves of the CCP,investigate the superiority of the ROC curves of the CCP,calculate critical values of the False Positive Rate(FPR),True Positive Rate(TPR),and cutoff of the optimal CCP,and give go/no go decisions at the interim of the optimal CCP.In addition,extensive numerical experiments are carried out to exemplify our theoretical results.Finally,a real data example is performed to illustrate the go/no go decisions of the optimal CCP.
基金supported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region(Grant No.2022D01B 187)。
文摘Federated learning(FL)is a distributed machine learning paradigm for edge cloud computing.FL can facilitate data-driven decision-making in tactical scenarios,effectively addressing both data volume and infrastructure challenges in edge environments.However,the diversity of clients in edge cloud computing presents significant challenges for FL.Personalized federated learning(pFL)received considerable attention in recent years.One example of pFL involves exploiting the global and local information in the local model.Current pFL algorithms experience limitations such as slow convergence speed,catastrophic forgetting,and poor performance in complex tasks,which still have significant shortcomings compared to the centralized learning.To achieve high pFL performance,we propose FedCLCC:Federated Contrastive Learning and Conditional Computing.The core of FedCLCC is the use of contrastive learning and conditional computing.Contrastive learning determines the feature representation similarity to adjust the local model.Conditional computing separates the global and local information and feeds it to their corresponding heads for global and local handling.Our comprehensive experiments demonstrate that FedCLCC outperforms other state-of-the-art FL algorithms.
基金Project(2022YFC3801000)supported by the National Key Research and Development Program of ChinaProject(232300421064)supported by the Natural Science Foundation of Henan Province,China+1 种基金Project(241111322700)supported by the Key Research and Development Projects in Henan Province,ChinaProject(52008379)supported by the National Natural Science Foundation of China。
文摘Recently,foamed polymers have been widely used in the repair of underground engineering disasters by grouting(trenchless technology)due to controllable gelation time and self-expansion.However,the grouting process becomes more complicated due to the complex geological conditions and the self-expansion of slurry.Therefore,this paper adopts a self-made visual experimental device with peripheral pressure and water plugging rate(WPR)monitoring functions to study the influence of main influencing parameters(particle size distribution,grouting amount and dynamic water pump pressure(DWPP))on the spatiotemporal distribution of slurry WPR and diffusion dynamic response(peripheral pressure).The results show that:When grouting amount is 563 g and DWPP is 0.013 MPa,the expansion force of the slurry in the diffusion process is dominant and can significantly change the local sand and gravel skeleton structure.When grouting amount is 563 g,DWPP is 0.013 MPa,and particle size distribution type isⅢ,the flow time of the polymer is shortened,the pores of the gravel are rapidly blocked.Then,the peripheral pressure decreases rapidly with the increase of the distance,and the time to reach the inflection point WPR is shortened.The instantaneous blockage of the pores leads to the delayed transmission of flow field blockage information.
基金Project(51975169)supported by the National Natural Science Foundation of ChinaProject(LH2022E085)supported by the Natural Science Foundation of Heilongjiang Province,China。
文摘Efficient tool condition monitoring techniques help to realize intelligent management of tool life and reduce tool usage costs.In this paper,the influence of different wear degrees of ball-end milling cutters on the texture shape of machining tool marks is investigated,and a method is proposed for predicting the wear state(including the position and degree of tool wear)of ball-end milling cutters based on entropy measurement of tool mark texture images.Firstly,data samples are prepared through wear experiments,and the change law of the tool mark texture shape with the tool wear state is analyzed.Then,a two-dimensional sample entropy algorithm is developed to quantify the texture morphology.Finally,the processing parameters and tool attitude are integrated into the prediction process to predict the wear value and wear position of the ball end milling cutter.After testing,the correlation between the predicted value and the standard value of the proposed tool condition monitoring method reaches 95.32%,and the accuracy reaches 82.73%,indicating that the proposed method meets the requirement of tool condition monitoring.
基金Project(52278380)supported by the National Natural Science Foundation of ChinaProject(2023JJ30670)supported by the National Science Foundation of and Technology Major Project of Hunan Province,China。
文摘This study proposes an alternative calculation mode for stresses on the slip surface(SS).The calculation of the normal stress(NS)on the SS involves examining its composition and expanding its unknown using the Taylor series.This expansion enables the reasonable construction of a function describing the NS on the SS.Additionally,by directly incorporating the nonlinear Generalized Hoke-Brown(GHB)strength criterion and utilizing the slope factor of safety(FOS)definition,a function of the shear stress on the SS is derived.This function considers the mutual feedback mechanism between the NS and strength parameters of the SS.The stress constraints conditions are then introduced at both ends of the SS based on the spatial stress relation of one point.Determining the slope FOS and stress solution for the SS involves considering the mechanical equilibrium conditions and the stress constraint conditions satisfied by the sliding body.The proposed approach successfully simulates the tension-shear stress zone near the slope top and provides an intuitive description of the concentration effect of compression-shear stress of the SS near the slope toe.Furthermore,compared to other methods,the present method demonstrates superior processing capabilities for the embedded nonlinear GHB strength criterion.
基金National Natural Science Foundation of China(71690233,71971213,71901214)。
文摘Architecture framework has become an effective method recently to describe the system of systems(SoS)architecture,such as the United States(US)Department of Defense Architecture Framework Version 2.0(DoDAF2.0).As a viewpoint in DoDAF2.0,the operational viewpoint(OV)describes operational activities,nodes,and resource flows.The OV models are important for SoS architecture development.However,as the SoS complexity increases,constructing OV models with traditional methods exposes shortcomings,such as inefficient data collection and low modeling standards.Therefore,we propose an intelligent modeling method for five OV models,including operational resource flow OV-2,organizational relationships OV-4,operational activity hierarchy OV-5a,operational activities model OV-5b,and operational activity sequences OV-6c.The main idea of the method is to extract OV architecture data from text and generate interoperable OV models.First,we construct the OV meta model based on the DoDAF2.0 meta model(DM2).Second,OV architecture named entities is recognized from text based on the bidirectional long short-term memory and conditional random field(BiLSTM-CRF)model.And OV architecture relationships are collected with relationship extraction rules.Finally,we define the generation rules for OV models and develop an OV modeling tool.We use unmanned surface vehicles(USV)swarm target defense SoS architecture as a case to verify the feasibility and effectiveness of the intelligent modeling method.
基金fully supported by a Tabung Amanah Pusat Pengurusan Penyelidikan&Inovasi(PPPI)(Grant No.PS060-UPNM/2023/GPPP/SG/1)Universiti Pertahanan Nasional Malaysia(UPNM)for funding this study。
文摘Solder joint,crucial component in electronic systems,face significant challenges when exposed to extreme conditions during applications.The solder joint reliability involving microstructure and mechanical properties will be affected by extreme conditions.Understanding the behaviour of solder joints under extreme conditions is vital to determine the durability and reliability of solder joint.This review paper aims to comprehensively explore the underlying failure mechanism affecting solder joint reliability under extreme conditions.This study covers an in-depth analysis of effect extreme temperature,mechanical stress,and radiation conditions towards solder joint.Impact of each condition to the microstructure including solder matrix and intermetallic compound layer,and mechanical properties such as fatigue,shear strength,creep,and hardness was thoroughly discussed.The failure mechanisms were illustrated in graphical diagrams to ensure clarity and understanding.Furthermore,the paper highlighted mitigation strategies that enhancing solder joint reliability under challenging operating conditions.The findings offer valuable guidance for researchers,engineers,and practitioners involved in electronics,engineering,and related fields,fostering advancements in solder joint reliability and performance.
基金National Science Foundation of Zhejiang under Contract(LY23E010001)。
文摘Structural health monitoring is widely utilized in outdoor environments,especially under harsh conditions,which can introduce noise into the monitoring system.Therefore,designing an effective denoising strategy to enhance the performance of guided wave damage detection in noisy environments is crucial.This paper introduces a local temporal principal component analysis(PCA)reconstruction approach for denoising guided waves prior to implementing unsupervised damage detection,achieved through novel autoencoder-based reconstruction.Experimental results demonstrate that the proposed denoising method significantly enhances damage detection performance when guided waves are contaminated by noise,with SNR values ranging from 10 to-5 dB.Following the implementation of the proposed denoising approach,the AUC score can elevate from 0.65 to 0.96 when dealing with guided waves corrputed by noise at a level of-5 dB.Additionally,the paper provides guidance on selecting the appropriate number of components used in the denoising PCA reconstruction,aiding in the optimization of the damage detection in noisy conditions.
基金the National Natural Science Foundation of China (Grant No.22105184)Research Fund of SWUST for PhD (Grant No.22zx7175)+1 种基金Sichuan Science and Technology Program (Grant No.2019ZDZX0013)Institute of Chemical Materials Program (Grant No.SXK-2022-03)for financial support。
文摘High purity and ultrafine DAAF(u-DAAF)is an emerging insensitive charge in initiators.Although there are many ways to obtain u-DAAF,developing a preparation method with stable operation,accurate control,good quality consistency,equipment miniaturization,and minimum manpower is an inevitable requirement to adapt to the current social technology development trend.Here reported is the microfluidic preparation of u-DAAF with tunable particle size by a passive swirling microreactor.Under the guidance of recrystallization growth kinetics and mixing behavior of fluids in the swirling microreactor,the key parameters(liquid flow rate,explosive concentration and crystallization temperature)were screened and optimized through screening experiments.Under the condition that no surfactant is added and only experimental parameters are controlled,the particle size of recrystallized DAAF can be adjusted from 98 nm to 785 nm,and the corresponding specific surface area is 8.45 m^(2)·g^(-1)to 1.33 m^(2)·g^(-1).In addition,the preparation method has good batch stability,high yield(90.8%-92.6%)and high purity(99.0%-99.4%),indicating a high practical application potential.Electric explosion derived flyer initiation tests demonstrate that the u-DAAF shows an initiation sensitivity much lower than that of the raw DAAF,and comparable to that of the refined DAAF by conventional spraying crystallization method.This study provides an efficient method to fabricate u-DAAF with narrow particle size distribution and high reproducibility as well as a theoretical reference for fabrication of other ultrafine explosives.
文摘Finding sustainable energy resources is essential to face the increasing energy demand.Trees are an important part of ancient architecture but are becoming rare in urban areas.Trees can control and tune the pedestrian-level wind velocity and thermal condition.In this study,a numerical investigation is employed to assess the role of trees planted in the windward direction of the building complex on the thermal and pedestrian wind velocity conditions around/inside a pre-education building located in the center of the complex.Compared to the previous studies(which considered only outside buildings),this work considers the effects of trees on microclimate change both inside/outside buildings.Effects of different parameters including the leaf area density and number of trees,number of rows,far-field velocity magnitude,and thermal condition around the main building are assessed.The results show that the flow velocity in the spacing between the first-row buildings is reduced by 30%-40% when the one-row trees with 2 m height are planted 15 m farther than the buildings.Furthermore,two rows of trees are more effective in higher velocities and reduce the maximum velocity by about 50%.The investigation shows that trees also could reduce the temperature by about 1℃around the building.
