Highly accurate manufacture in machining industry can only be obtained with precise temperature control of the coolant （oil or water）.Machine tool with more accurate,stable and advanced the precision of the working ...Highly accurate manufacture in machining industry can only be obtained with precise temperature control of the coolant （oil or water）.Machine tool with more accurate,stable and advanced the precision of the working component cannot be developed without appropriate cooling.However,the machine tool coolers are facing the control hunting of cooling temperature and the dramatic variation of heat load in high-accuracy machining.The main objective of this study is to evaluate the influence of the hot-gas by-pass scheme and suction regulation for capacity control of a machine tool cooler system.In this study,experimental investigation on both hot-gas by-pass scheme and suction valve regulation for capacity control has been proposed.Effects of using capillary tube and thermostatic expansion valve along with different capacity control scheme have been investigated extensively in an environmental testing room.Cooling performance and power consumption of the cooler system have been measured and analyzed as well by comparing with different opening percentage of throttling valve under specific coolant temperature.The experimental results reveal that the power consumption will reduce slightly by capacity control using the hot-gas by-pass scheme but the coefficient of performance （COP） of the overall system will decrease.Lower coolant temperature will result in higher compressor power consumption as well.While conducting suction valve regulating for capacity control,energy-saving at 10%-12% can be obtained by using thermostatic expansion valve under different evaporator load.It also reveals that suction valve regulation along with adequate choice of thermostatic expansion valve can provide alternative choice for steady capacity control and substantial energy-saving.The proposed cooler systems with different capacity control schemes are not only more cost-effective than inverter driven system,but also can perform energy-saving and precise temperature control specific for high-accuracy machine tool cooling.展开更多
逆F类功放在接近饱和区工作时效率很高,将其与Doherty功放结构相结合,可以实现一种在大功率回退的情况下仍然具有很高效率的射频功率放大器。本文设计了一款基于Ga N HEMT晶体管的高效率的逆F类Doherty功率放大器,工作频带为910MHz^950...逆F类功放在接近饱和区工作时效率很高,将其与Doherty功放结构相结合,可以实现一种在大功率回退的情况下仍然具有很高效率的射频功率放大器。本文设计了一款基于Ga N HEMT晶体管的高效率的逆F类Doherty功率放大器,工作频带为910MHz^950MHz。单音信号测试结果显示,在930MHz处,功放回退7.5d B后漏极效率仍高达64.2%。使用3载波WCDMA信号作为测试信号,利用数字预失真技术进行线性化后,功放输出信号的上下边带邻信道功率比(ACPR)分别为-35.39d Bc和-35.9d Bc。展开更多
Through the study on relation between the gas phase basicity of aliphatic alcohol,ether and amine and their four kinds of electron effects:inductive effect,conjugative effect,field effect and polarizability effect,the...Through the study on relation between the gas phase basicity of aliphatic alcohol,ether and amine and their four kinds of electron effects:inductive effect,conjugative effect,field effect and polarizability effect,the model of gas phase basicity for aliphatic alcohol,ether and amine was described as following:PA(kJ/mol)=2535.1431+316.4274∑I+523.9595PEI-802.6512X_i-544.5804Q_x-9328.6803∑I/PEI+5048.4806∑I/X_i-1070.5125 PEI/X_i.The result of regression analysis showed that the above equation is a good expression for the varying rule of the gas phase basicity of aliphatic alcohol,ehter,and amine.It can provide a relatively reliable model to calculate and predict accurately gas phase basicity for aliphatic alcohol,ether and amine.展开更多
基金supported by Science Committee of Taiwan,China(Grant No. NSC 98-2622-E-167-029-CC3),and Industrial Technology Research Institute,Taiwan,China
文摘Highly accurate manufacture in machining industry can only be obtained with precise temperature control of the coolant （oil or water）.Machine tool with more accurate,stable and advanced the precision of the working component cannot be developed without appropriate cooling.However,the machine tool coolers are facing the control hunting of cooling temperature and the dramatic variation of heat load in high-accuracy machining.The main objective of this study is to evaluate the influence of the hot-gas by-pass scheme and suction regulation for capacity control of a machine tool cooler system.In this study,experimental investigation on both hot-gas by-pass scheme and suction valve regulation for capacity control has been proposed.Effects of using capillary tube and thermostatic expansion valve along with different capacity control scheme have been investigated extensively in an environmental testing room.Cooling performance and power consumption of the cooler system have been measured and analyzed as well by comparing with different opening percentage of throttling valve under specific coolant temperature.The experimental results reveal that the power consumption will reduce slightly by capacity control using the hot-gas by-pass scheme but the coefficient of performance （COP） of the overall system will decrease.Lower coolant temperature will result in higher compressor power consumption as well.While conducting suction valve regulating for capacity control,energy-saving at 10%-12% can be obtained by using thermostatic expansion valve under different evaporator load.It also reveals that suction valve regulation along with adequate choice of thermostatic expansion valve can provide alternative choice for steady capacity control and substantial energy-saving.The proposed cooler systems with different capacity control schemes are not only more cost-effective than inverter driven system,but also can perform energy-saving and precise temperature control specific for high-accuracy machine tool cooling.
文摘Through the study on relation between the gas phase basicity of aliphatic alcohol,ether and amine and their four kinds of electron effects:inductive effect,conjugative effect,field effect and polarizability effect,the model of gas phase basicity for aliphatic alcohol,ether and amine was described as following:PA(kJ/mol)=2535.1431+316.4274∑I+523.9595PEI-802.6512X_i-544.5804Q_x-9328.6803∑I/PEI+5048.4806∑I/X_i-1070.5125 PEI/X_i.The result of regression analysis showed that the above equation is a good expression for the varying rule of the gas phase basicity of aliphatic alcohol,ehter,and amine.It can provide a relatively reliable model to calculate and predict accurately gas phase basicity for aliphatic alcohol,ether and amine.
