Practically,the load currents in three phases are asymmetric in the power system.It means that the impedances are different in all three phases.If the consumer’s transformer neutral cut off and/or was disconnected fr...Practically,the load currents in three phases are asymmetric in the power system.It means that the impedances are different in all three phases.If the consumer’s transformer neutral cut off and/or was disconnected from the neutral of power supply source,then there will be some trouble and failure occurred.The current in the neutral wire drops down to zero when the neutral wire is cut off and the phase currents of all three-phase equal to each other since there was no return wire.The currents are equal but the voltages at the phase consumers are different.Especially for residential single-phase consumers,the voltage at the consumers of the phase varies differently for three phase systems when the neutral wire was disconnected at consumer side and even the voltage at the consumers one or two of those three phases becomes over nominal voltage or reaches nearly line voltage.In this case,the electronic appliances in that phase will be fed by high voltage than the rated value and they can be broken down.In the power system of UB(Ulaanbaatar)city,there are some occasional such kind of failures every year.Obviously,many electronic appliances were broken down due to high voltage and the electricity utility companies respond for service charge of damaged parts.展开更多
The recovery stress characteristics of a TiNi shape memory alloy wire under different constraint conditions were studied. The results show that the recovery stress rate (dσ/dT) in the second heating cycle increases s...The recovery stress characteristics of a TiNi shape memory alloy wire under different constraint conditions were studied. The results show that the recovery stress rate (dσ/dT) in the second heating cycle increases significantly with the increasing constraining-spring coefficient in the first heating cycle. As a result, a distinct discontinuity appears on the recovery stress curves of the TiNi alloy wires in the second heating process. Also, the results of differential scanning calorimeter(DSC) measurements show that after the thermomechanical process, the heating curve of the TiNi alloy wire consists of two independent endothermic peaks.展开更多
The existing problems in the manufacture of SWRH82B high carbon steel wire were discussed by sampling and testing the microstructure and properties of the steel from the workshop. To solve the problems, the experiment...The existing problems in the manufacture of SWRH82B high carbon steel wire were discussed by sampling and testing the microstructure and properties of the steel from the workshop. To solve the problems, the experimental parameters for thermal simulation were optimized, and the thermal simulating experiments were carded out on a Gleeblel500 thermal simulator. The process parameters for the manufacture were optimized after analysis of the data, and the productive experiments were performed after the water box in front of the no-twist blocks was reconstructed, to control the temperature of the loop layer. The results from the productive experiments showed that the cooling rate of 10-15℃/s was reasonable before phase transformation, about 5℃/s during phase transformation, and 600-620℃ was the suitable starting temperature for phase transformation. The ultimate strength of the Ф11.0 mm wire was increased to 1150-1170 MPa with an increase of 20-30 MPa, the percentage reduction of section was to 34%-36% with an increase of 1%-3% by testing the finished products after reconstruction.展开更多
Mathematical investigations of the dynamic response of buried systems to thermal and/or electromagnetic stimulation continues to be of great importance. The size of such systems can range from the microelectronic scal...Mathematical investigations of the dynamic response of buried systems to thermal and/or electromagnetic stimulation continues to be of great importance. The size of such systems can range from the microelectronic scale to large underground structures. Stimulation can occur from unwanted electromagnetic signals entering the buried system, and for assessing the operating state of a buried system that is not usually physically accessible. In both cases detecting damage or status can be accomplished by examining the time dependence of the resultant surface temperature. This study shows how to determine surface temperature for a hypothetical thermal-plus-systems using a combination of Fourier-space and Laplace-time transform techniques. The hypothetical model can be generalized from scaling the relevant relationships.展开更多
文摘Practically,the load currents in three phases are asymmetric in the power system.It means that the impedances are different in all three phases.If the consumer’s transformer neutral cut off and/or was disconnected from the neutral of power supply source,then there will be some trouble and failure occurred.The current in the neutral wire drops down to zero when the neutral wire is cut off and the phase currents of all three-phase equal to each other since there was no return wire.The currents are equal but the voltages at the phase consumers are different.Especially for residential single-phase consumers,the voltage at the consumers of the phase varies differently for three phase systems when the neutral wire was disconnected at consumer side and even the voltage at the consumers one or two of those three phases becomes over nominal voltage or reaches nearly line voltage.In this case,the electronic appliances in that phase will be fed by high voltage than the rated value and they can be broken down.In the power system of UB(Ulaanbaatar)city,there are some occasional such kind of failures every year.Obviously,many electronic appliances were broken down due to high voltage and the electricity utility companies respond for service charge of damaged parts.
基金Project(50071037) supported by the National Natural Science Foundation of China Project supported by the ScientificResearch Foundation for the Returned Overseas Chinese Scholars Education Ministry of China
文摘The recovery stress characteristics of a TiNi shape memory alloy wire under different constraint conditions were studied. The results show that the recovery stress rate (dσ/dT) in the second heating cycle increases significantly with the increasing constraining-spring coefficient in the first heating cycle. As a result, a distinct discontinuity appears on the recovery stress curves of the TiNi alloy wires in the second heating process. Also, the results of differential scanning calorimeter(DSC) measurements show that after the thermomechanical process, the heating curve of the TiNi alloy wire consists of two independent endothermic peaks.
文摘The existing problems in the manufacture of SWRH82B high carbon steel wire were discussed by sampling and testing the microstructure and properties of the steel from the workshop. To solve the problems, the experimental parameters for thermal simulation were optimized, and the thermal simulating experiments were carded out on a Gleeblel500 thermal simulator. The process parameters for the manufacture were optimized after analysis of the data, and the productive experiments were performed after the water box in front of the no-twist blocks was reconstructed, to control the temperature of the loop layer. The results from the productive experiments showed that the cooling rate of 10-15℃/s was reasonable before phase transformation, about 5℃/s during phase transformation, and 600-620℃ was the suitable starting temperature for phase transformation. The ultimate strength of the Ф11.0 mm wire was increased to 1150-1170 MPa with an increase of 20-30 MPa, the percentage reduction of section was to 34%-36% with an increase of 1%-3% by testing the finished products after reconstruction.
文摘Mathematical investigations of the dynamic response of buried systems to thermal and/or electromagnetic stimulation continues to be of great importance. The size of such systems can range from the microelectronic scale to large underground structures. Stimulation can occur from unwanted electromagnetic signals entering the buried system, and for assessing the operating state of a buried system that is not usually physically accessible. In both cases detecting damage or status can be accomplished by examining the time dependence of the resultant surface temperature. This study shows how to determine surface temperature for a hypothetical thermal-plus-systems using a combination of Fourier-space and Laplace-time transform techniques. The hypothetical model can be generalized from scaling the relevant relationships.
