Theoretical and experimental analysis of a new refrigerant mixture BY-3 was conducted based on a single-stage vapor compression refrigeration system. The water-water heat pump system used BY-3 to produce hot water whe...Theoretical and experimental analysis of a new refrigerant mixture BY-3 was conducted based on a single-stage vapor compression refrigeration system. The water-water heat pump system used BY-3 to produce hot water when the low temperature was 20 ℃. The following results were obtained: the highest temperature at the condenser outlet reached about 85 ℃; when the difference between the water temperatures at the condenser outlet and the evaporator inlet was less than 40 ℃, the coefficient of performance (COP) was larger than 4; when the difference reached 55 ℃, the COP still kept 3; the discharge temperature of BY-3 was lower than 100 ℃, and the refrigerant vapor pressure kept lower than 1.8 MPa. When the water temperature at the condenser outlet reached over 85 ℃, nearly a 5 ℃ superheating temperature was maintained.展开更多
目的了解广州市花都区男男同性恋(Men who have six with men,MSM)的艾滋病(Acquired immunodeficiency syndrome,AIDS)确诊患者流行特征及人口学构成差异,为该特殊人群的艾滋病防治提供理论经验。方法通过哨点监测的方法调查2010—201...目的了解广州市花都区男男同性恋(Men who have six with men,MSM)的艾滋病(Acquired immunodeficiency syndrome,AIDS)确诊患者流行特征及人口学构成差异,为该特殊人群的艾滋病防治提供理论经验。方法通过哨点监测的方法调查2010—2016年间,该区121名存在男男同性恋行为的艾滋病确诊患者,分析该人群的人口学构成差异、商业性行为、感染途径和伴发主要性疾病。结果 121名男男同性恋艾滋病患者的户籍(χ2=1.93,P=0.59)、年龄(χ2=0.45,P=0.93)、学历(χ2=0.27,P=0.98)、月收入水平(χ2=0.91,P=0.64)构成差异无统计学意义(P>0.05);其中的93人(76.86%)存在商业性行为;主要传播途径为同性传播110例(90.91%),其传播途径构成的差异有统计学意义(χ2=34.14,P=0.04);对象的各类性病构成的差异有统计学意义(χ2=12.56,P=0.03),主要疾病为梅毒(26.63%)、生殖器疱疹(23.08%)、淋病(20.12%)。结论广州市某区男男同性恋艾滋病患者人口学构成较为复杂,广泛存在商业性行为,同性性行为是导致其感染主要原因,梅毒、生殖器疱疹、淋病为其伴发的主要疾病。展开更多
采用C语言建立了碳化硅（SiC）晶体生长炉三维温度场数值模拟平台,基于柱坐标系构建生长炉物理模型,采用有限体积法离散数学模型,利用S2S（Surface to Surface）辐射模型考察了生长室内的辐射换热特性,提出判断辐射面可视性的最短距离法...采用C语言建立了碳化硅（SiC）晶体生长炉三维温度场数值模拟平台,基于柱坐标系构建生长炉物理模型,采用有限体积法离散数学模型,利用S2S（Surface to Surface）辐射模型考察了生长室内的辐射换热特性,提出判断辐射面可视性的最短距离法.模拟了电流强度1250 A、电流频率16 k Hz条件下的生长炉温度场,定量揭示了生长室内的辐射换热强度;采用标准偏差法研究了线圈结构对晶体内部温度及温度梯度均匀性的影响.结果表明,螺旋电磁加热线圈容易导致生长炉内部温度场呈非轴对称分布;辐射热流较导热热流大102-103倍,辐射换热促使生长室内温度分布均匀;螺旋线圈的布置方式使晶体截面温度呈非轴对称分布,造成温度梯度的均匀性变差,晶体生长过程中容易产生热应力,影响晶体质量.展开更多
基金Supported by Major State Basic Research Development Program of China ("973" Program, No. 2009CB219907)the Program for Changjiang Scholars and Innovative Research Team in University (No. IRT0936)
文摘Theoretical and experimental analysis of a new refrigerant mixture BY-3 was conducted based on a single-stage vapor compression refrigeration system. The water-water heat pump system used BY-3 to produce hot water when the low temperature was 20 ℃. The following results were obtained: the highest temperature at the condenser outlet reached about 85 ℃; when the difference between the water temperatures at the condenser outlet and the evaporator inlet was less than 40 ℃, the coefficient of performance (COP) was larger than 4; when the difference reached 55 ℃, the COP still kept 3; the discharge temperature of BY-3 was lower than 100 ℃, and the refrigerant vapor pressure kept lower than 1.8 MPa. When the water temperature at the condenser outlet reached over 85 ℃, nearly a 5 ℃ superheating temperature was maintained.
文摘目的了解广州市花都区男男同性恋(Men who have six with men,MSM)的艾滋病(Acquired immunodeficiency syndrome,AIDS)确诊患者流行特征及人口学构成差异,为该特殊人群的艾滋病防治提供理论经验。方法通过哨点监测的方法调查2010—2016年间,该区121名存在男男同性恋行为的艾滋病确诊患者,分析该人群的人口学构成差异、商业性行为、感染途径和伴发主要性疾病。结果 121名男男同性恋艾滋病患者的户籍(χ2=1.93,P=0.59)、年龄(χ2=0.45,P=0.93)、学历(χ2=0.27,P=0.98)、月收入水平(χ2=0.91,P=0.64)构成差异无统计学意义(P>0.05);其中的93人(76.86%)存在商业性行为;主要传播途径为同性传播110例(90.91%),其传播途径构成的差异有统计学意义(χ2=34.14,P=0.04);对象的各类性病构成的差异有统计学意义(χ2=12.56,P=0.03),主要疾病为梅毒(26.63%)、生殖器疱疹(23.08%)、淋病(20.12%)。结论广州市某区男男同性恋艾滋病患者人口学构成较为复杂,广泛存在商业性行为,同性性行为是导致其感染主要原因,梅毒、生殖器疱疹、淋病为其伴发的主要疾病。
文摘采用C语言建立了碳化硅（SiC）晶体生长炉三维温度场数值模拟平台,基于柱坐标系构建生长炉物理模型,采用有限体积法离散数学模型,利用S2S（Surface to Surface）辐射模型考察了生长室内的辐射换热特性,提出判断辐射面可视性的最短距离法.模拟了电流强度1250 A、电流频率16 k Hz条件下的生长炉温度场,定量揭示了生长室内的辐射换热强度;采用标准偏差法研究了线圈结构对晶体内部温度及温度梯度均匀性的影响.结果表明,螺旋电磁加热线圈容易导致生长炉内部温度场呈非轴对称分布;辐射热流较导热热流大102-103倍,辐射换热促使生长室内温度分布均匀;螺旋线圈的布置方式使晶体截面温度呈非轴对称分布,造成温度梯度的均匀性变差,晶体生长过程中容易产生热应力,影响晶体质量.
