期刊文献+
共找到11,082篇文章
< 1 2 250 >
每页显示 20 50 100
Spatiotemporal Evaluation and Future Projection of Diurnal Temperature Range over the Tibetan Plateau in CMIP6 Models
1
作者 Suguo ZHANG Qin HU +2 位作者 Xianhong MENG Yaqiong LÜ Xianyu YANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第11期2245-2258,共14页
The diurnal temperature range(DTR) serves as a vital indicator reflecting both natural climate variability and anthropogenic climate change. This study investigates the historical and projected multitemporal DTR varia... The diurnal temperature range(DTR) serves as a vital indicator reflecting both natural climate variability and anthropogenic climate change. This study investigates the historical and projected multitemporal DTR variations over the Tibetan Plateau. It assesses 23 climate models from phase 6 of the Coupled Model Intercomparison Project(CMIP6) using CN05.1 observational data as validation, evaluating their ability to simulate DTR over the Tibetan Plateau. Then, the evolution of DTR over the Tibetan Plateau under different shared socioeconomic pathway(SSP) scenarios for the near,middle, and long term of future projection are analyzed using 11 selected robustly performing models. Key findings reveal:(1) Among the models examined, BCC-CSM2-MR, EC-Earth3, EC-Earth3-CC, EC-Earth3-Veg, EC-Earth3-Veg-LR,FGOALS-g3, FIO-ESM-2-0, GFDL-ESM4, MPI-ESM1-2-HR, MPI-ESM1-2-LR, and INM-CM5-0 exhibit superior integrated simulation capability for capturing the spatiotemporal variability of DTR over the Tibetan Plateau.(2) Projection indicates a slightly increasing trend in DTR on the Tibetan Plateau in the SSP1-2.6 scenario, and decreasing trends in the SSP2-4.5, SSP3-7.0, and SPP5-8.5 scenarios. In certain areas, such as the southeastern edge of the Tibetan Plateau, western hinterland of the Tibetan Plateau, southern Kunlun, and the Qaidam basins, the changes in DTR are relatively large.(3) Notably, the warming rate of maximum temperature under SSP2-4.5, SSP3-7.0, and SPP5-8.5 is slower compared to that of minimum temperature, and it emerges as the primary contributor to the projected decrease in DTR over the Tibetan Plateau in the future. 展开更多
关键词 Tibetan Plateau CMIP6 models diurnal temperature range model assessment historical period future projection
下载PDF
Seasonal constraint of dynamic water temperature on riverine dissolved inorganic nitrogen transport in land surface modeling
2
作者 Shuang Liu Kaiheng Hu +1 位作者 Zhenghui Xie Yan Wang 《Atmospheric and Oceanic Science Letters》 CSCD 2024年第4期35-40,共6页
水体温度变化对河流可溶性无机氮(DIN)输送有着强烈控制作用.然而,在全球尺度上河流DIN输送量对水温度变化的响应尚不清楚.因此,本文基于陆面过程模式,耦合河流水温估算和DIN传输方案,设定有,无动态水温情景,对比研究陆面模拟中水温变... 水体温度变化对河流可溶性无机氮(DIN)输送有着强烈控制作用.然而,在全球尺度上河流DIN输送量对水温度变化的响应尚不清楚.因此,本文基于陆面过程模式,耦合河流水温估算和DIN传输方案,设定有,无动态水温情景,对比研究陆面模拟中水温变化对河流DIN通量变化的影响.结果表明:在考虑水温动态变化后,在30°N和30°S之间, DIN通量年振幅减小5%–25%.在中国东部地区,水温动态变化使河流DIN通量在夏季减少1%–3%,在冬季增加1%–5%,对DIN通量具有明显的季节性约束作用,表明动态水温的表达在河流DIN输送模拟中的重要性. 展开更多
关键词 陆面模拟 河流氮输送 水温变化 季节变化 全球尺度
下载PDF
Temperature field model in surface grinding: a comparative assessment 被引量:3
3
作者 Min Yang Ming Kong +10 位作者 Changhe Li Yunze Long Yanbin Zhang Shubham Sharma Runze Li Teng Gao Mingzheng Liu Xin Cui Xiaoming Wang Xiao Ma Yuying Yang 《International Journal of Extreme Manufacturing》 SCIE EI CAS CSCD 2023年第4期314-373,共60页
Grinding is a crucial process in machining workpieces because it plays a vital role in achieving the desired precision and surface quality.However,a significant technical challenge in grinding is the potential increas... Grinding is a crucial process in machining workpieces because it plays a vital role in achieving the desired precision and surface quality.However,a significant technical challenge in grinding is the potential increase in temperature due to high specific energy,which can lead to surface thermal damage.Therefore,ensuring control over the surface integrity of workpieces during grinding becomes a critical concern.This necessitates the development of temperature field models that consider various parameters,such as workpiece materials,grinding wheels,grinding parameters,cooling methods,and media,to guide industrial production.This study thoroughly analyzes and summarizes grinding temperature field models.First,the theory of the grinding temperature field is investigated,classifying it into traditional models based on a continuous belt heat source and those based on a discrete heat source,depending on whether the heat source is uniform and continuous.Through this examination,a more accurate grinding temperature model that closely aligns with practical grinding conditions is derived.Subsequently,various grinding thermal models are summarized,including models for the heat source distribution,energy distribution proportional coefficient,and convective heat transfer coefficient.Through comprehensive research,the most widely recognized,utilized,and accurate model for each category is identified.The application of these grinding thermal models is reviewed,shedding light on the governing laws that dictate the influence of the heat source distribution,heat distribution,and convective heat transfer in the grinding arc zone on the grinding temperature field.Finally,considering the current issues in the field of grinding temperature,potential future research directions are proposed.The aim of this study is to provide theoretical guidance and technical support for predicting workpiece temperature and improving surface integrity. 展开更多
关键词 grinding temperature uniform continuous temperature field nonuniform discontinuous temperature field heat source distribution model grinding heat distribution coefficient model convective heat transfer coefficient model
下载PDF
Effects of the Water-Cement Ratio and the Molding Temperature on the Hydration Heat of Cement
4
作者 代金鹏 HE Jie +1 位作者 WANG Qicai LOU Xuyu 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第4期990-998,共9页
The effects of the water-cement ratio and the molding temperature on the hydration heat of cement were investigated with semi-adiabatic calorimetry.The specimens were prepared with water-cement ratios of 0.31,0.38,and... The effects of the water-cement ratio and the molding temperature on the hydration heat of cement were investigated with semi-adiabatic calorimetry.The specimens were prepared with water-cement ratios of 0.31,0.38,and 0.45,and the molding temperature was specified at 10 and 20℃.The experimental results show that,as the water-binder ratio increases,the value of the second temperature peak on the temperature curve of the cement paste decreases,and the age at which the peak appears is delayed.The higher the water-cement ratio,the higher the hydration heat release in the early period of cement hydration,but this trend reverses in the late period.There are intersection points of the total hydration heat curve of the cement pastes under the influence of the water-cement ratio,and this law can be observed at both molding temperatures.With the increase in the molding temperature,the age of the second temperature peak on the temperature curve of the cement paste will advance,but the temperature peak will decrease.The higher the molding temperature,the earlier the acceleration period of the cement hydration began,and the larger the hydration heat of the cement in the early stage,but the smaller the total heat in the late period.A subsection function calculation model of the hydration heat,which was based on the existing models,was proposed in order to predict the heat of the hydration of the concrete. 展开更多
关键词 semi-adiabatic calorimetry hydration heat water-cement ratio molding temperature modelING
下载PDF
Theoretical characterization of the temperature-dependent saturation magnetization of magnetic metallic materials
5
作者 吴金龙 董攀 +6 位作者 贺屹 马艳丽 李梓源 姚沁远 邱俊 麻建坐 李卫国 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第7期577-585,共9页
Based on the force-heat equivalence energy density principle,a theoretical model for magnetic metallic materials is developed,which characterizes the temperature-dependent magnetic anisotropy energy by considering the... Based on the force-heat equivalence energy density principle,a theoretical model for magnetic metallic materials is developed,which characterizes the temperature-dependent magnetic anisotropy energy by considering the equivalent relationship between magnetic anisotropy energy and heat energy;then the relationship between the magnetic anisotropy constant and saturation magnetization is considered.Finally,we formulate a temperature-dependent model for saturation magnetization,revealing the inherent relationship between temperature and saturation magnetization.Our model predicts the saturation magnetization for nine different magnetic metallic materials at different temperatures,exhibiting satisfactory agreement with experimental data.Additionally,the experimental data used as reference points are at or near room temperature.Compared to other phenomenological theoretical models,this model is considerably more accessible than the data required at 0 K.The index included in our model is set to a constant value,which is equal to 10/3 for materials other than Fe,Co,and Ni.For transition metals(Fe,Co,and Ni in this paper),the index is 6 in the range of 0 K to 0.65T_(cr)(T_(cr) is the critical temperature),and 3 in the range of 0.65T_(cr) to T_(cr),unlike other models where the adjustable parameters vary according to each material.In addition,our model provides a new way to design and evaluate magnetic metallic materials with superior magnetic properties over a wide range of temperatures. 展开更多
关键词 magnetic metallic materials temperature dependent saturation magnetization modelING
下载PDF
Effect of sample temperature on femtosecond laser ablation of copper
6
作者 党伟杰 陈雨桐 +1 位作者 陈安民 金明星 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第2期377-385,共9页
We conduct an experimental study supported by theoretical analysis of single laser ablating copper to investigate the interactions between laser and material at different sample temperatures,and predict the changes of... We conduct an experimental study supported by theoretical analysis of single laser ablating copper to investigate the interactions between laser and material at different sample temperatures,and predict the changes of ablation morphology and lattice temperature.For investigating the effect of sample temperature on femtosecond laser processing,we conduct experiments on and simulate the thermal behavior of femtosecond laser irradiating copper by using a two-temperature model.The simulation results show that both electron peak temperature and the relaxation time needed to reach equilibrium increase as initial sample temperature rises.When the sample temperature rises from 300 K to 600 K,the maximum lattice temperature of the copper surface increases by about 6500 K under femtosecond laser irradiation,and the ablation depth increases by 20%.The simulated ablation depths follow the same general trend as the experimental values.This work provides some theoretical basis and technical support for developing femtosecond laser processing in the field of metal materials. 展开更多
关键词 femtosecond laser two-temperature model sample temperature ablation depth
下载PDF
Factors Influencing the Spatial Variability of Air Temperature Urban Heat Island Intensity in Chinese Cities
7
作者 Heng LYU Wei WANG +3 位作者 Keer ZHANG Chang CAO Wei XIAO Xuhui LEE 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第5期817-829,共13页
Few studies have investigated the spatial patterns of the air temperature urban heat island(AUHI)and its controlling factors.In this study,the data generated by an urban climate model were used to investigate the spat... Few studies have investigated the spatial patterns of the air temperature urban heat island(AUHI)and its controlling factors.In this study,the data generated by an urban climate model were used to investigate the spatial variations of the AUHI across China and the underlying climate and ecological drivers.A total of 355 urban clusters were used.We performed an attribution analysis of the AUHI to elucidate the mechanisms underlying its formation.The results show that the midday AUHI is negatively correlated with climate wetness(humid:0.34 K;semi-humid:0.50 K;semi-arid:0.73 K).The annual mean midnight AUHI does not show discernible spatial patterns,but is generally stronger than the midday AUHI.The urban–rural difference in convection efficiency is the largest contributor to the midday AUHI in the humid(0.32±0.09 K)and the semi-arid(0.36±0.11 K)climate zones.The release of anthropogenic heat from urban land is the dominant contributor to the midnight AUHI in all three climate zones.The rural vegetation density is the most important driver of the daytime and nighttime AUHI spatial variations.A spatial covariance analysis revealed that this vegetation influence is manifested mainly through its regulation of heat storage in rural land. 展开更多
关键词 air temperature urban heat island spatial variations biophysical drivers Chinese cities climate model
下载PDF
Design of weak current measurement system and research on temperature impact
8
作者 Chu-Xiang Zhao San-Gang Li +8 位作者 Rong-Rong Su Li Yang Ming-Zhe Liu Qing-Yue Xue Shan Liao Zhi Zhou Qing-Shan Tan Xian-Guo Tuo Yi Cheng 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第4期46-56,共11页
A dedicated weak current measurement system was designed to measure the weak currents generated by the neutron ionization chamber.This system incorporates a second-order low-pass filter circuit and the Kalman filterin... A dedicated weak current measurement system was designed to measure the weak currents generated by the neutron ionization chamber.This system incorporates a second-order low-pass filter circuit and the Kalman filtering algorithm to effectively filter out noise and minimize interference in the measurement results.Testing conducted under normal temperature conditions has demonstrated the system's high precision performance.However,it was observed that temperature variations can affect the measurement performance.Data were collected across temperatures ranging from -20 to 70℃,and a temperature correction model was established through linear regression fitting to address this issue.The feasibility of the temperature correction model was confirmed at temperatures of -5 and 40℃,where relative errors remained below 0.1% after applying the temperature correction.The research indicates that the designed measurement system exhibits excellent temperature adaptability and high precision,making it particularly suitable for measuring weak currents. 展开更多
关键词 Weak current measurement system Neutron ionization chamber Kalman filter algorithm temperature correction model
下载PDF
Spatial Variation in CO_(2) Concentration Improves the Simulated Surface Air Temperature Increase in the Northern Hemisphere
9
作者 Jing PENG Li DAN Xiba TANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第8期1614-1628,1676-1685,共25页
The increasing concentration of atmospheric CO_(2) since the Industrial Revolution has affected surface air temperature.However,the impact of the spatial distribution of atmospheric CO_(2) concentration on surface air... The increasing concentration of atmospheric CO_(2) since the Industrial Revolution has affected surface air temperature.However,the impact of the spatial distribution of atmospheric CO_(2) concentration on surface air temperature biases remains highly unclear.By incorporating the spatial distribution of satellite-derived atmospheric CO_(2) concentration in the Beijing Normal University Earth System Model,this study investigated the increase in surface air temperature since the Industrial Revolution in the Northern Hemisphere(NH) under historical conditions from 1976-2005.In comparison with the increase in surface temperature simulated using a uniform distribution of CO_(2),simulation with a nonuniform distribution of CO_(2)produced better agreement with the Climatic Research Unit(CRU) data in the NH under the historical condition relative to the baseline over the period 1901-30.Hemispheric June-July-August(JJA) surface air temperature increased by 1.28℃ ±0.29℃ in simulations with a uniform distribution of CO_(2),by 1.00℃±0.24℃ in simulations with a non-uniform distribution of CO_(2),and by 0.24℃ in the CRU data.The decrease in downward shortwave radiation in the non-uniform CO_(2) simulation was primarily attributable to reduced warming in Eurasia,combined with feedbacks resulting from increased leaf area index(LAI) and latent heat fluxes.These effects were more pronounced in the non-uniform CO_(2)simulation compared to the uniform CO_(2) simulation.Results indicate that consideration of the spatial distribution of CO_(2)concentration can reduce the overestimated increase in surface air temperature simulated by Earth system models. 展开更多
关键词 spatial variations of CO_(2) surface air temperature Earth system model land surface albedo leaf area index
下载PDF
A study on temperature monitoring method for inverter IGBT based on memory recurrent neural network
10
作者 Yunhe Liu Tengfei Guo +2 位作者 Jinda Li Chunxing Pei Jianqiang Liu 《High-Speed Railway》 2024年第1期64-70,共7页
The power module of the Insulated Gate Bipolar Transistor(IGBT)is the core component of the traction transmission system of high-speed trains.The module's junction temperature is a critical factor in determining d... The power module of the Insulated Gate Bipolar Transistor(IGBT)is the core component of the traction transmission system of high-speed trains.The module's junction temperature is a critical factor in determining device reliability.Existing temperature monitoring methods based on the electro-thermal coupling model have limitations,such as ignoring device interactions and high computational complexity.To address these issues,an analysis of the parameters influencing IGBT failure is conducted,and a temperature monitoring method based on the Macro-Micro Attention Long Short-Term Memory(MMALSTM)recursive neural network is proposed,which takes the forward voltage drop and collector current as features.Compared with the traditional electricalthermal coupling model method,it requires fewer monitoring parameters and eliminates the complex loss calculation and equivalent thermal resistance network establishment process.The simulation model of a highspeed train traction system has been established to explore the accuracy and efficiency of MMALSTM-based prediction methods for IGBT power module junction temperature.The simulation outcomes,which deviate only 3.2% from the theoretical calculation results of the electric-thermal coupling model,confirm the reliability of this approach for predicting the temperature of IGBT power modules. 展开更多
关键词 IGBT Electro-thermal coupling model Junction temperature monitoring Loss model Neural networks
下载PDF
Analysis of piezoelectric semiconductor fibers under gradient temperature changes
11
作者 Shuangpeng LI Ruoran CHENG +1 位作者 Nannan MA Chunli ZHANG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2024年第2期311-320,共10页
Piezoelectric semiconductors(PSs)possess both semiconducting properties and piezoelectric coupling effects,making them optimal building blocks for semiconductor devices.PS fiber-like structures have wide applications ... Piezoelectric semiconductors(PSs)possess both semiconducting properties and piezoelectric coupling effects,making them optimal building blocks for semiconductor devices.PS fiber-like structures have wide applications in multi-functional semiconductor devices.In this paper,a one-dimensional(1D)theoretical model is established to describe the piezotronic responses of a PS fiber under gradient temperature changes.The theoretical model aims to explain the mechanism behind the resistance change caused by such gradient temperature changes.Numerical results demonstrate that a gradient temperature change significantly affects the physical fields within the PS fiber,and can induce changes in its surface resistance.It provides important theoretical guidance on the development of piezotronic devices that are sensitive to temperature effects. 展开更多
关键词 piezoelectric semiconductor(PS)fiber one-dimensional(1D)model piezotronic effect gradient temperature change
下载PDF
Effect of Milk Processed Arnebiae Radix on Body Temperature of Fever Rats
12
作者 Jinwen LIU Xiaohong MA +4 位作者 Huayang ZHAO Liga BAI Liming BAO Qishisan WU Yongji LI 《Medicinal Plant》 2024年第4期89-91,共3页
[Objectives]To investigate the synergistic effect of Arnebiae Radix after processing.[Methods]The effects of raw Arnebiae Radix and milk processed Arnebiae Radix on hypothermia in yeast-induced febrile rats were compa... [Objectives]To investigate the synergistic effect of Arnebiae Radix after processing.[Methods]The effects of raw Arnebiae Radix and milk processed Arnebiae Radix on hypothermia in yeast-induced febrile rats were compared.[Results]The processed and unprocessed Arnebiae Radix at high,medium and low doses all had a certain effect on inhibiting the rise of body temperature in rats.The high dose unprocessed group,the medium dose processed group and the high dose processed group had the best inhibitory effect on body temperature,the low dose processed group could delay the fever time,and the low dose unprocessed group had poor inhibitory effect on fever.[Conclusions]The prepared Arnebiae Radix has enhanced drug effect,and milk processed Arnebiae Radix can be used to replace common Arnebiae Radix to reduce the dosage of Arnebiae Radix and save Arnebiae Radix resources. 展开更多
关键词 Arnebiae Radix Fever model Body temperature
下载PDF
Mechanical properties and damage constitutive model of sandstone after acid corrosion and high temperature treatments 被引量:1
13
作者 Qijian Chen Youliang Chen +3 位作者 Peng Xiao Xi Du Yungui Pan Rafig Azzam 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2023年第6期747-760,共14页
Aiming at the problem of temperature-mechanics-chemical(T-M-C)action encountered by rocks in underground engineering,sandstone was selected as the sample for acid corrosion treatment at pH 1,3,5 and 7,the acid corrosi... Aiming at the problem of temperature-mechanics-chemical(T-M-C)action encountered by rocks in underground engineering,sandstone was selected as the sample for acid corrosion treatment at pH 1,3,5 and 7,the acid corrosion treated samples were then subjected to high-temperature experiments at 25,300,600,and 900℃,and triaxial compression experiments were conducted in the laboratory.The experimental results show that the superposition of chemical damage and thermal damage has a significant impact on the quality,wave velocity,porosity and compression failure characteristics of the rock.Based on the Lemaitre strain equivalent hypothesis theory,the damage degree of rock material was described by introducing damage variables,and the spatial mobilized plane(SMP)criterion was adopted.The damage constitutive model can well reflect the stress-strain characteristics of the rock triaxial compression process,which verified the rationality and reliability of the model parameters.The experiment and constitutive model analyzed the change law of mechanical properties of rock after chemical corrosion and high temperature thermal damage,which had certain practical significance for rock engineering construction. 展开更多
关键词 Acid corrosion High temperature Mechanical properties Damage variable SMP criterion Constitutive model
下载PDF
Numerical Analysis on Temperature Distribution in a Single Cell of PEFC Operated at Higher Temperature by1D Heat Transfer Model and 3D Multi-Physics Simulation Model
14
作者 Akira Nishimura Kyohei Toyoda +1 位作者 Daiki Mishima Eric Hu 《Energy and Power Engineering》 CAS 2023年第5期205-227,共23页
This study is to understand the impact of operating conditions, especially initial operation temperature (T<sub>ini</sub>) which is set in a high temperature range, on the temperature profile of the interf... This study is to understand the impact of operating conditions, especially initial operation temperature (T<sub>ini</sub>) which is set in a high temperature range, on the temperature profile of the interface between the polymer electrolyte membrane (PEM) and the catalyst layer at the cathode (i.e., the reaction surface) in a single cell of polymer electrolyte fuel cell (PEFC). A 1D multi-plate heat transfer model based on the temperature data of the separator measured using the thermograph in a power generation experiment was developed to evaluate the reaction surface temperature (T<sub>react</sub>). In addition, to validate the proposed heat transfer model, T<sub>react</sub> obtained from the model was compared with that from the 3D numerical simulation using CFD software COMSOL Multiphysics which solves the continuity equation, Brinkman equation, Maxwell-Stefan equation, Butler-Volmer equation as well as heat transfer equation. As a result, the temperature gap between the results obtained by 1D heat transfer model and those obtained by 3D numerical simulation is below approximately 0.5 K. The simulation results show the change in the molar concentration of O<sub>2</sub> and H<sub>2</sub>O from the inlet to the outlet is more even with the increase in T<sub>ini</sub> due to the lower performance of O<sub>2</sub> reduction reaction. The change in the current density from the inlet to the outlet is more even with the increase in T<sub>ini</sub> and the value of current density is smaller with the increase in T<sub>ini </sub>due to the increase in ohmic over-potential and concentration over-potential. It is revealed that the change in T<sub>react</sub> from the inlet to the outlet is more even with the increase in T<sub>ini</sub> irrespective of heat transfer model. This is because the generated heat from the power generation is lower with the increase in T<sub>ini </sub>due to the lower performance of O<sub>2</sub> reduction reaction. 展开更多
关键词 PEFC Heat Transfer model temperature Distribution Numerical Simulation High temperature Operation
下载PDF
Effect of Ultra-low Temperature on Carbonation Performance of SFRRC and Prediction Model
15
作者 钱维民 苏骏 +1 位作者 ZHAO Jiayu JI Wei 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第4期778-788,共11页
Through the rapid carbonation test of SFRRC with different fiber volume fractions at ultralow temperature,the influence of ultra-low temperature damage on the carbonation resistance of SFRRC was analyzed,which provide... Through the rapid carbonation test of SFRRC with different fiber volume fractions at ultralow temperature,the influence of ultra-low temperature damage on the carbonation resistance of SFRRC was analyzed,which provides a theoretical basis for the application of SFRRC in ultra-low temperature engineering.The experimental results show that ultra-low temperatures can significantly weaken the carbonization resistance of SFRRC.When the temperature reaches 160℃,the carbonization depth increases by 67.66%compared with the normal state.The proper amount of steel fiber has an evident influence on the carbonation resistance of the material.However,when the addition amount exceeds the optimum content,the carbonation resistance of the material decreases.The grey prediction model established by constructing the original sequence can reasonably predict the carbonation resistance of SFRRC after ultra-low temperatures. 展开更多
关键词 ultra-low temperature SFRRC CARBONIZATION grey model
下载PDF
Tensile Properties and Prediction Model of Recombinant Bamboo at Different Temperatures
16
作者 Kunpeng Zhao Yang Wei +2 位作者 Si Chen Kang Zhao Mingmin Ding 《Journal of Renewable Materials》 SCIE EI 2023年第6期2695-2712,共18页
The destruction of recombinant bamboo depends on many factors,and the complex ambient temperature is an important factor affecting its basic mechanical properties.To investigate the failure mechanism and stress–strai... The destruction of recombinant bamboo depends on many factors,and the complex ambient temperature is an important factor affecting its basic mechanical properties.To investigate the failure mechanism and stress–strain relationship of recombinant bamboo at different temperatures,eighteen tensile specimens of recombinant bamboo were tested.The results showed that with increasing ambient temperature,the typical failure modes of recombinant bamboo were flush fracture,toothed failure,and serrated failure.The ultimate tensile strength,ultimate strain and elastic modulus of recombinant bamboo decreased with increasing temperature,and the ultimate tensile stress decreased from 154.07 to 96.55 MPa,a decrease of 37.33%,and the ultimate strain decreased from 0.011 to 0.008,a decrease of 26.57%.Based on the Ramberg-Osgood model and the pseudo‒elastic design method,a predictive model was established for the tensile stress–strain relationship of recombinant bamboo considering the temperature level.The model can accurately evaluate the tensile stress–strain relationship of recombinant bamboo under different temperature conditions. 展开更多
关键词 Recombinant bamboo temperature tensile behaviour stress-strain relationship predictive model
下载PDF
Improving maize growth and development simulation by integrating temperature compensatory effect under plastic film mulching into the AquaCrop model
17
作者 Chao Zhang Jiying Kong +3 位作者 Min Tang Wen Lin Dianyuan Ding Hao Feng 《The Crop Journal》 SCIE CSCD 2023年第5期1559-1568,共10页
Temperature compensatory effect, which quantifies the increase in cumulative air temperature from soil temperature increase caused by mulching, provides an effective method for incorporating soil temperature into crop... Temperature compensatory effect, which quantifies the increase in cumulative air temperature from soil temperature increase caused by mulching, provides an effective method for incorporating soil temperature into crop models. In this study, compensated temperature was integrated into the AquaCrop model to investigate the capability of the compensatory effect to improve assessment of the promotion of maize growth and development by plastic film mulching(PM). A three-year experiment was conducted from2014 to 2016 with two maize varieties(spring and summer) and two mulching conditions(PM and non-mulching(NM)), and the AquaCrop model was employed to reproduce crop growth and yield responses to changes in NM, PM, and compensated PM. A marked difference in soil temperature between NM and PM was observed before 50 days after sowing(DAS) during three growing seasons. During sowing–emergence and emergence–tasseling, the increase in air temperature was proportional to the compensatory coefficient, with spring maize showing a higher compensatory temperature than summer maize. Simulation results for canopy cover(CC) were generally in good agreement with the measurements, whereas predictions of aboveground biomass and grain yield under PM indicated large underestimates from 60 DAS to the end of maturity. Simulations of spring maize biomass and yield showed general increase based on temperature compensation, accompanied by improvement in modeling accuracy, with RMSEs decreasing from 2.5 to 1.6 t ha^(-1)and from 4.1 t to 3.4 t ha^(-1). Improvement in biomass and yield simulation was less pronounced for summer than for spring maize, implying that crops grown during low-temperature periods would benefit more from the compensatory effect. This study demonstrated the effectiveness of the temperature compensatory effect to improve the performance of the AquaCrop model in simulating maize growth under PM practices. 展开更多
关键词 Plastic film mulching Soil temperature Compensatory effect AquaCrop model Maize growth
下载PDF
A phenomenological model for plastic flow behavior of rotating band material with a large temperature range
18
作者 Yi-cheng Zhu Jia-wei Fu +1 位作者 Lin-fang Qian Jing-hua Cao 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第7期121-133,共13页
The plastic flow behavior of the rotating band material is investigated in this paper. The rotating band material is processed from H96 brass alloy, which is hardened to a much higher yield strength compared to the an... The plastic flow behavior of the rotating band material is investigated in this paper. The rotating band material is processed from H96 brass alloy, which is hardened to a much higher yield strength compared to the annealed one. The dynamically uniaxial compression behavior of the material is tested using the split Hopkinson pressure bar(SHPB) with temperature and strain rate ranging from 297 to 1073 K and500 to 3000 s^(-1), respectively, and a phenomenological plastic flow stress model is developed to describe the mechanical behavior of the material. The material is found to present noticeable temperature sensitivity and weak strain-rate sensitivity. The construction of the plastic flow stress model has two steps. Firstly, three univariate stress functions, taking plastic strain, plastic strain rate and temperature as independent variable, respectively, are proposed by fixing the other two variables. Then, as the three univariate functions describe the special cases of flow stress behavior under various conditions, the principle of stress compatibility is adopted to obtain the complete flow stress function. The numerical results show that the proposed plastic flow stress model is more suitable for the rotating band material than the existing well-known models. 展开更多
关键词 Rotating band Plastic flow behavior Large temperature range Phenomenological model
下载PDF
IGBT Temperature Field Monitoring Based on Reduced-order Model
19
作者 Ziyu Zhou Yi Su +3 位作者 Xu Zhang Chengde Tong Ping Zheng Mingjun Zhu 《CES Transactions on Electrical Machines and Systems》 CSCD 2023年第2期129-136,共8页
With the rapid development of the world economy,IGBT has been widely used in motor drive and electric energy conversion.In order to timely detect the fatigue damage of IGBT,it is necessary to monitor the junction temp... With the rapid development of the world economy,IGBT has been widely used in motor drive and electric energy conversion.In order to timely detect the fatigue damage of IGBT,it is necessary to monitor the junction temperature of IGBT.In order to realize the fast calculation of IGBT junction temperature,a finite element method of IGBT temperature field reduction is proposed in this paper.Firstly,the finite element calculation process of IGBT temperature field is introduced and the linear equations of finite element calculation of temperature field are derived.Temperature field data of different working conditions are obtained by finite element simulation to form the sample space.Then the covariance matrix of the sample space is constructed,whose proper orthogonal decomposition and modal extraction are carried out.Reasonable basis vector space is selected to complete the low dimensional expression of temperature vector inside and outside the sample space.Finally,the reduced-order model of temperature field finite element is obtained and solved.The results of the reduced order model are compared with those of the finite element method,and the performance of the reduced-order model is evaluated from two aspects of accuracy and rapidity. 展开更多
关键词 IGBT Junction temperature Proper orthogonal decomposition Reduced-order model
下载PDF
Energy model based sensorless estimation method for operational temperature of braking resistor onboard metro vehicles
20
作者 Leiting Zhao Kan Liu +1 位作者 Donghui Liu Zheming Jin 《Railway Sciences》 2023年第4期470-485,共16页
Purpose–This study aims to improve the availability of regenerative braking for urban metro vehicles by introducing a sensorless operational temperature estimation method for the braking resistor(BR)onboard the vehic... Purpose–This study aims to improve the availability of regenerative braking for urban metro vehicles by introducing a sensorless operational temperature estimation method for the braking resistor(BR)onboard the vehicle,which overcomes the vulnerability of having conventional temperature sensor.Design/methodology/approach–In this study,the energy model based sensorless estimation method is developed.By analyzing the structure and the convection dissipation process of the BR onboard the vehicle,the energy-based operational temperature model of the BR and its cooling domain is established.By adopting Newton’s law of cooling and the law of conservation of energy,the energy and temperature dynamic of the BR can be stated.To minimize the use of all kinds of sensors(including both thermal and electrical),a novel regenerative braking power calculation method is proposed,which involves only the voltage of DC traction network and the duty cycle of the chopping circuit;both of them are available for the traction control unit(TCU)of the vehicle.By utilizing a real-time iterative calculation and updating the parameter of the energy model,the operational temperature of the BR can be obtained and monitored in a sensorless manner.Findings–In this study,a sensorless estimation/monitoring method of the operational temperature of BR is proposed.The results show that it is possible to utilize the existing electrical sensors that is mandatory for the traction unit’s operation to estimate the operational temperature of BR,instead of adding dedicated thermal sensors.The results also validate the effectiveness of the proposal is acceptable for the engineering practical.Originality/value–The proposal of this study provides novel concepts for the sensorless operational temperature monitoring of BR onboard rolling stocks.The proposed method only involves quasi-global electrical variable and the internal control signal within the TCU. 展开更多
关键词 Operational temperature monitoring Braking resistor Regenerative braking Energy model Convection dissipation of heat
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部