Indoor thermal comfort and passive solar heating technologies have been extensively studied.However,few studies have explored the suitability of passive solar heating technologies based on differentiated thermal comfo...Indoor thermal comfort and passive solar heating technologies have been extensively studied.However,few studies have explored the suitability of passive solar heating technologies based on differentiated thermal comfort demands.This work took the rural dwellings in Northwest China as the research object.First,the current indoor and outdoor thermal environment in winter and the mechanism of residents’differentiated demand for indoor thermal comfort were obtained through tests,questionnaires,and statistical analysis.Second,a comprehensive passive optimized design of existing buildings was conducted,and the validity of the optimized combination scheme was explored using DesignBuilder software.Finally,the suitability of passive solar heating technology for each region in Northwest China was analyzed based on residents’differentiated demand for indoor thermal comfort.The regions were then classified according to the suitability of the technology for these.The results showed that the indoor heating energy consumption was high and the indoor thermal environment was not ideal,yet the solar energy resources were abundant.Indoor comfort temperature indexes that match the functional rooms and usage periods were proposed.For the buildings with the optimized combination scheme,the average indoor temperature was increased significantly and the temperature fluctuation was decreased dramatically.Most regions in Northwest China were suitable for the development of passive solar heating technology.Based on the obtained suitability of the technology for the regions of Northwest China,these were classified into most suitable,more suitable,less suitable,and unsuitable regions.展开更多
To solve the problem of insufficient ability when detecting the high-speed moving target with passive millimeter wave technology, a direct-detection passive millimeter wave detecting system using the monolithic microw...To solve the problem of insufficient ability when detecting the high-speed moving target with passive millimeter wave technology, a direct-detection passive millimeter wave detecting system using the monolithic microwave integrated cir- cuit （MMIC） millimeter wave radiometer is built, and the measured data are obtained by experiment under different condi- tions. Based on feature analysis of testing signals, it points out that the peak of the first pulse and interval of two peak pulses are valid features which can reflect the motion characteristic of target. A method to calculate the moving speed of target is put forward. The calculating results indicate that the proposed method has enough accuracy and is feasible to determine the parameters of the moving target using for passive millimeter wave system.展开更多
In order to utilize integrated passive technology in printed circuit boards （PCBs）, manufacturing processing for integrated resistors by lamination method was investigated. Integrated resistors fabricated from Ohmeg...In order to utilize integrated passive technology in printed circuit boards （PCBs）, manufacturing processing for integrated resistors by lamination method was investigated. Integrated resistors fabricated from Ohmega technologies in the experiment were 1 408 pieces per panel with four different patterns A, B, C and D and four resistance values of 25, 50, 75 and 100 fL Six panel per batch and four batches were performed totally. The testing was done for 960 pieces of integrated resistors randomly selected with the same size. The value distribution ranges and the relative standard deviation （RSD） show that the scatter degree of the resistance decreases with the resistor size increasing and/or with the resistance increasing. Patterns D with resistance of 75 and 100% for four patterns have the resistance value variances less than 10%. Patterns C and D with resistance of 100 Ω have the manufacturing tolerance less than 10%. The process capabilities are from about 0.6 to 1.6 for the designed testing patterns, which shows that the integrated resistors fabricated have the potential to be used in multilayer PCBs in the future.展开更多
Traditional magneto-electric vibration sensors and servo accelerometers have severe shortcomings when used to measure vibration where low frequency components predominate.A low frequency characteristic extension for v...Traditional magneto-electric vibration sensors and servo accelerometers have severe shortcomings when used to measure vibration where low frequency components predominate.A low frequency characteristic extension for velocity vibration sensors is presented in this paper.The passive circuit technology,active compensation technology and the closed- cycle pole compensation technology are used to extend the measurable range and to improve low frequency characteristics of sensors.Thses three types of low frequency velocity vibration sensors have been developed and widely adopted in China.展开更多
Radiative cooling has emerged as an attractive passive cooling technology in energy and thermal management fields due to its zero-energy consumption and pollution-free characteristics[[1],[2],[3]].An ideal radiative c...Radiative cooling has emerged as an attractive passive cooling technology in energy and thermal management fields due to its zero-energy consumption and pollution-free characteristics[[1],[2],[3]].An ideal radiative cooling material should simultaneously exhibit high solar reflectance to minimize solar heat absorption and high infrared emissivity in the“atmospheric window”band(8–13μm)to directly radiate heat to outer space(∼3 K),achieving passive cooling without energy input[[4],[5],[6]].Photonic structures(such as nano-multilayers,nano-pores,and photonic crystals)have been proven to simultaneously achieve high solar reflectance and broadband infrared emissivity[7,8].For instance,commercial“cooling paints”(such as BaSO4 and TiO2-based reflective paints)can reduce surface temperatures by several degrees and moderately decrease building cooling loads.展开更多
China’s Tibet autonomous region has abundant solar energy resources,cold winters,and cool summers.These are ideal conditions for the application of passive solar heating methods.However,differences in climatic condit...China’s Tibet autonomous region has abundant solar energy resources,cold winters,and cool summers.These are ideal conditions for the application of passive solar heating methods.However,differences in climatic conditions and building types can significantly affect passive solar technology’s feasibility,which makes it challenging to promote passive solar buildings in Tibet.In this study,the suitability zone for passive solar technology is categorized based on the sub-zoning indicators for Tibet.By modeling between direct gain windows,Trombe walls,and attached sunspaces,the effect of indoor thermal environments and the capacity for heating load reduction is compared for different passive solar technologies.The climate-difference impact analysis shows that the I-B-1 zone is better suited for passive solar technology than other climate zones.More specifically,this zone has an average energy-saving rate difference of up to 28.61%compared to the II-A-1 zone.The analysis of the impact of building type differences indicates that residential buildings have higher Trombe wall-to-wall ratio limits and more significant potential for energy savings than office buildings.The study also clarifies the implications of Tibet’s climate conditions and building type differences on the effectiveness of passive solar technology.Moreover,it recommends appropriate passive solar technology adoption methods for every climate zone.This study can be used as a reference and engineering guide to improving the indoor thermal environment of Tibetan buildings,tailored to the highly variable local conditions.展开更多
Different treatment technologies have been efficiently applied to remove heavy metals from waste- water. Efforts have been made to find out the most economic water treatment technology by using low cost and easily acc...Different treatment technologies have been efficiently applied to remove heavy metals from waste- water. Efforts have been made to find out the most economic water treatment technology by using low cost and easily accessible natural materials. On the other hand, heavy metals are the most threatening groundwater contaminants because of their toxicity and harmful effects on human and biota. This review discusses the use of natural geological materials for heavy metal removal in aqueous systems. Special attention has been devoted to natural limestone through a systematic inventory of relevant published reports. The removal of toxic metals may include different mechanisms （e.g., physisorption, chemisorptions, precipitation, etc.）, depending on the physico-chemical properties of the material and the removed metal. Sorption of toxic metals （e.g., Pb, Cu, Cd, Zn, Cr, Hg, etc.） onto natural limestone involved precipitation of metal carbonate as a predominant removal process, but often subordinated by adsorption and ion exchange, depending on the physico-chemical properties of the studied limestone.展开更多
Trombe walls have significant energy-saving features and are therefore of great interest to researchers.However,additional research about the Trombe wall is needed to reduce indoor temperature fluctuations and to impr...Trombe walls have significant energy-saving features and are therefore of great interest to researchers.However,additional research about the Trombe wall is needed to reduce indoor temperature fluctuations and to improve thermal behavior under different climatic conditions.A new Trombe wall system was proposed which uses Venetian blinds and a basement.The field tests were conducted to compare the thermal performance of four types of rooms:(ⅰ)no Trombe wall(control),(ⅱ)classical Trombe wall(TW),(ⅲ)Trombe wall with Venetian blinds(TW+VB),and(ⅳ)Trombe wall with Venetian blinds and a basement(TW+VB+B).The field measurements were conducted during the winter near Shihezi City in northwest China.The objective of this study was(ⅰ)to evaluate the thermal performance of a novel Trombe wall system under different operation conditions,and(ⅱ)to confirm the optimal angle of Venetian blinds during the heating period.The results demonstrated that the TW+VB+B system effectively reduced indoor temperature fluctuations after sunset.Furthermore,during the daytime,the average air temperatures in the test rooms were 13.6℃higher in the TW+VB+B system than in the control.The average temperature at the air outlet in the TW+VB+B system was 4.9℃higher than that in the TW+VB system during the daytime,and the average predicted mean vote(PMV)of the test room was 1.02 units greater in the TW+VB+B system than in the control.The thermal efficiency remains in the range of 40%-65%when the Venetian blind angle was set at 45°.In conclusion,the experiment results showed that the TW+VB+B system can not only reduce indoor temperature fluctuations but also improve thermal performance in winter.Both the heating energy consumption in buildings and pollutants emission in the environment were lessened through the application of this passive solar energy-saving technology.Therefore,this can provide valuable insights for improving the thermal performance of the novel Trombe Wall system in such village houses.展开更多
Shallow geothermal systems use the thermal inertia of the earth to provide a temperature gradient between the ambient conditions and the underground soil.This thermal inertia can be used by the heat exchangers to prov...Shallow geothermal systems use the thermal inertia of the earth to provide a temperature gradient between the ambient conditions and the underground soil.This thermal inertia can be used by the heat exchangers to provide space heating and cooling during the winters and summers.This paper provides a brief but broad overview of the different active and passive technologies involved in the use of heat exchangers for HVAC in order to achieve a near net zero energy building.Firstly the different types of ground heat exchangers and heat pumps are introduced along with the relevant studies of significance in this field.It has been demonstrated that the different types of heat exchangers can be integrated with thermally active building envelopes and renewable energy resources to significantly minimize the building energy use.Finally a pathway has been devised for use of ground heat exchangers to realize a net zero energy building.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52078419 and 51678483)supported by the Doctoral Dissertation Innovation Fund of Xi’an University of Technology(310–252072116).
文摘Indoor thermal comfort and passive solar heating technologies have been extensively studied.However,few studies have explored the suitability of passive solar heating technologies based on differentiated thermal comfort demands.This work took the rural dwellings in Northwest China as the research object.First,the current indoor and outdoor thermal environment in winter and the mechanism of residents’differentiated demand for indoor thermal comfort were obtained through tests,questionnaires,and statistical analysis.Second,a comprehensive passive optimized design of existing buildings was conducted,and the validity of the optimized combination scheme was explored using DesignBuilder software.Finally,the suitability of passive solar heating technology for each region in Northwest China was analyzed based on residents’differentiated demand for indoor thermal comfort.The regions were then classified according to the suitability of the technology for these.The results showed that the indoor heating energy consumption was high and the indoor thermal environment was not ideal,yet the solar energy resources were abundant.Indoor comfort temperature indexes that match the functional rooms and usage periods were proposed.For the buildings with the optimized combination scheme,the average indoor temperature was increased significantly and the temperature fluctuation was decreased dramatically.Most regions in Northwest China were suitable for the development of passive solar heating technology.Based on the obtained suitability of the technology for the regions of Northwest China,these were classified into most suitable,more suitable,less suitable,and unsuitable regions.
文摘To solve the problem of insufficient ability when detecting the high-speed moving target with passive millimeter wave technology, a direct-detection passive millimeter wave detecting system using the monolithic microwave integrated cir- cuit （MMIC） millimeter wave radiometer is built, and the measured data are obtained by experiment under different condi- tions. Based on feature analysis of testing signals, it points out that the peak of the first pulse and interval of two peak pulses are valid features which can reflect the motion characteristic of target. A method to calculate the moving speed of target is put forward. The calculating results indicate that the proposed method has enough accuracy and is feasible to determine the parameters of the moving target using for passive millimeter wave system.
基金Project(041010) supported by Start-Up Foundation of Northwest University,ChinaProject(UIT/39) supported by University-Industry Collaboration Program from the Innovation and Technology Fund of Hong Kong,China
文摘In order to utilize integrated passive technology in printed circuit boards （PCBs）, manufacturing processing for integrated resistors by lamination method was investigated. Integrated resistors fabricated from Ohmega technologies in the experiment were 1 408 pieces per panel with four different patterns A, B, C and D and four resistance values of 25, 50, 75 and 100 fL Six panel per batch and four batches were performed totally. The testing was done for 960 pieces of integrated resistors randomly selected with the same size. The value distribution ranges and the relative standard deviation （RSD） show that the scatter degree of the resistance decreases with the resistor size increasing and/or with the resistance increasing. Patterns D with resistance of 75 and 100% for four patterns have the resistance value variances less than 10%. Patterns C and D with resistance of 100 Ω have the manufacturing tolerance less than 10%. The process capabilities are from about 0.6 to 1.6 for the designed testing patterns, which shows that the integrated resistors fabricated have the potential to be used in multilayer PCBs in the future.
基金The Ministry of Science and Technology Special Foundation Grant No.217Harbin Important Science Technology Foundation Grant No.0014211044
文摘Traditional magneto-electric vibration sensors and servo accelerometers have severe shortcomings when used to measure vibration where low frequency components predominate.A low frequency characteristic extension for velocity vibration sensors is presented in this paper.The passive circuit technology,active compensation technology and the closed- cycle pole compensation technology are used to extend the measurable range and to improve low frequency characteristics of sensors.Thses three types of low frequency velocity vibration sensors have been developed and widely adopted in China.
基金supported by the National Natural Science Foundation of China(52273085)the Natural Science Foundation of Henan Province(252300421087).
文摘Radiative cooling has emerged as an attractive passive cooling technology in energy and thermal management fields due to its zero-energy consumption and pollution-free characteristics[[1],[2],[3]].An ideal radiative cooling material should simultaneously exhibit high solar reflectance to minimize solar heat absorption and high infrared emissivity in the“atmospheric window”band(8–13μm)to directly radiate heat to outer space(∼3 K),achieving passive cooling without energy input[[4],[5],[6]].Photonic structures(such as nano-multilayers,nano-pores,and photonic crystals)have been proven to simultaneously achieve high solar reflectance and broadband infrared emissivity[7,8].For instance,commercial“cooling paints”(such as BaSO4 and TiO2-based reflective paints)can reduce surface temperatures by several degrees and moderately decrease building cooling loads.
基金supported by the National Key Research and Development Project(No.2019YFE0104900)Joint Fund for Regional Innovation and Development of National Natural Science Foundation of China(No.U20A20311)the National Natural Science Foundation of China(No.52008329).
文摘China’s Tibet autonomous region has abundant solar energy resources,cold winters,and cool summers.These are ideal conditions for the application of passive solar heating methods.However,differences in climatic conditions and building types can significantly affect passive solar technology’s feasibility,which makes it challenging to promote passive solar buildings in Tibet.In this study,the suitability zone for passive solar technology is categorized based on the sub-zoning indicators for Tibet.By modeling between direct gain windows,Trombe walls,and attached sunspaces,the effect of indoor thermal environments and the capacity for heating load reduction is compared for different passive solar technologies.The climate-difference impact analysis shows that the I-B-1 zone is better suited for passive solar technology than other climate zones.More specifically,this zone has an average energy-saving rate difference of up to 28.61%compared to the II-A-1 zone.The analysis of the impact of building type differences indicates that residential buildings have higher Trombe wall-to-wall ratio limits and more significant potential for energy savings than office buildings.The study also clarifies the implications of Tibet’s climate conditions and building type differences on the effectiveness of passive solar technology.Moreover,it recommends appropriate passive solar technology adoption methods for every climate zone.This study can be used as a reference and engineering guide to improving the indoor thermal environment of Tibetan buildings,tailored to the highly variable local conditions.
文摘Different treatment technologies have been efficiently applied to remove heavy metals from waste- water. Efforts have been made to find out the most economic water treatment technology by using low cost and easily accessible natural materials. On the other hand, heavy metals are the most threatening groundwater contaminants because of their toxicity and harmful effects on human and biota. This review discusses the use of natural geological materials for heavy metal removal in aqueous systems. Special attention has been devoted to natural limestone through a systematic inventory of relevant published reports. The removal of toxic metals may include different mechanisms （e.g., physisorption, chemisorptions, precipitation, etc.）, depending on the physico-chemical properties of the material and the removed metal. Sorption of toxic metals （e.g., Pb, Cu, Cd, Zn, Cr, Hg, etc.） onto natural limestone involved precipitation of metal carbonate as a predominant removal process, but often subordinated by adsorption and ion exchange, depending on the physico-chemical properties of the studied limestone.
基金funded by the National Natural Science Foundation of China,grant number 51778119.
文摘Trombe walls have significant energy-saving features and are therefore of great interest to researchers.However,additional research about the Trombe wall is needed to reduce indoor temperature fluctuations and to improve thermal behavior under different climatic conditions.A new Trombe wall system was proposed which uses Venetian blinds and a basement.The field tests were conducted to compare the thermal performance of four types of rooms:(ⅰ)no Trombe wall(control),(ⅱ)classical Trombe wall(TW),(ⅲ)Trombe wall with Venetian blinds(TW+VB),and(ⅳ)Trombe wall with Venetian blinds and a basement(TW+VB+B).The field measurements were conducted during the winter near Shihezi City in northwest China.The objective of this study was(ⅰ)to evaluate the thermal performance of a novel Trombe wall system under different operation conditions,and(ⅱ)to confirm the optimal angle of Venetian blinds during the heating period.The results demonstrated that the TW+VB+B system effectively reduced indoor temperature fluctuations after sunset.Furthermore,during the daytime,the average air temperatures in the test rooms were 13.6℃higher in the TW+VB+B system than in the control.The average temperature at the air outlet in the TW+VB+B system was 4.9℃higher than that in the TW+VB system during the daytime,and the average predicted mean vote(PMV)of the test room was 1.02 units greater in the TW+VB+B system than in the control.The thermal efficiency remains in the range of 40%-65%when the Venetian blind angle was set at 45°.In conclusion,the experiment results showed that the TW+VB+B system can not only reduce indoor temperature fluctuations but also improve thermal performance in winter.Both the heating energy consumption in buildings and pollutants emission in the environment were lessened through the application of this passive solar energy-saving technology.Therefore,this can provide valuable insights for improving the thermal performance of the novel Trombe Wall system in such village houses.
文摘Shallow geothermal systems use the thermal inertia of the earth to provide a temperature gradient between the ambient conditions and the underground soil.This thermal inertia can be used by the heat exchangers to provide space heating and cooling during the winters and summers.This paper provides a brief but broad overview of the different active and passive technologies involved in the use of heat exchangers for HVAC in order to achieve a near net zero energy building.Firstly the different types of ground heat exchangers and heat pumps are introduced along with the relevant studies of significance in this field.It has been demonstrated that the different types of heat exchangers can be integrated with thermally active building envelopes and renewable energy resources to significantly minimize the building energy use.Finally a pathway has been devised for use of ground heat exchangers to realize a net zero energy building.
