Cu,Cu-2.2%Al and Cu-4.5%Al with stacking fault energies（SFE） of 78,35 and 7 mJ/m2 respectively were processed by cold-rolling（CR） at liquid nitrogen temperature（77 K） after hot-rolling.X-ray diffraction measurem...Cu,Cu-2.2%Al and Cu-4.5%Al with stacking fault energies（SFE） of 78,35 and 7 mJ/m2 respectively were processed by cold-rolling（CR） at liquid nitrogen temperature（77 K） after hot-rolling.X-ray diffraction measurements indicate that a decrease in SFE leads to a decrease in crystallite size but increase in microstrain,dislocation and twin densities of the CR processed samples.Tensile tests at room temperature indicate that as the stacking fault energy decreases,the strength and ductility increase.The results indicate that decreasing stacking fault energy is an optimum method to improve the ductility without loss of strength.展开更多
Pressure drops and heat transfer over staggered pin fin heat sinks with top bypass flow were experimentally evaluated. The authors considered liquid-cooling applications because there were few data available comparing...Pressure drops and heat transfer over staggered pin fin heat sinks with top bypass flow were experimentally evaluated. The authors considered liquid-cooling applications because there were few data available comparing to air-cooling applications. Empirical equations to predict heat transfer on the endwall were developed by obtaining experimental data on the copper base plate with acrylic pins. A new model for predicting pressure drops and heat transfer over staggered pin fin heat sinks with top bypass flow based on mass, momentum, and energy conservation within the two control volumes is proposed. The first control volume in the model is located within the finned area, and the second is located in the gap between the tip of the pins and the flow channel. This model combines two conditions according to the boundary-layer thickness. A comparison between experimental and calculated results revealed that dimensionless pressure drops and the Nusselt number could be predicted within 30% error for the former and 50% error for the latter.展开更多
Experimental investigation of the microfiltration （MF） using a revolving cross-flow membrane filter was performed under the condition of constant pressure difference, and different flat membranes made of polyvinylid...Experimental investigation of the microfiltration （MF） using a revolving cross-flow membrane filter was performed under the condition of constant pressure difference, and different flat membranes made of polyvinylidene fluoride （PVDF, 0.1 μm）, cellulose acetate （CA, 0.22 μm）, sulfonated polyethersulfone （SPES, 0.22 μm） and polyamide （PA, 0.45 μm）, respectively, were used in filtration experiments. The dependence of the filtrate mass of the cross-flow MF on time was measured on-line. The experimental results showed that the effect of the cross-flow on high viscosity medium was more significant than that on the low viscosity one.展开更多
Using the results of aftershock relocation, inversion on seismic waves and InSAR results, and surface rupture displacements obtained by geological survey after the earthquake, this paper constructs a fault model of th...Using the results of aftershock relocation, inversion on seismic waves and InSAR results, and surface rupture displacements obtained by geological survey after the earthquake, this paper constructs a fault model of the Yushu Ms7. 1 earthquake. Based on rectangular dislocation theory in an elastic-viscoelastic layered medium, we have simulated the co- seismic deformation and gravity change with gravitational effect considered. The pictures show that the absolute gravity measuring point is beside the extremum of coseismic gravity change, and the numerical value reaches 25.02 x 10-Sm. s-2. After a discussion about the gravity changes before the earthquake and the coherence consistency between two FG-5 absolute gravimeters, we think that the measured value 27.2 × 10^-8 m· s^-2 at Yushu station is coseismic gravity change. It＇s coincident with the simulation results based on dislocation theory. Therefore it is a good tool to test the near-field changes found by dislocation theory.展开更多
By using the method of least square linear fitting to analyze data do not exist errors under certain conditions, in order to make the linear data fitting method that can more accurately solve the relationship expressi...By using the method of least square linear fitting to analyze data do not exist errors under certain conditions, in order to make the linear data fitting method that can more accurately solve the relationship expression between the volume and quantity in scientific experiments and engineering practice, this article analyzed data error by commonly linear data fitting method, and proposed improved process of the least distance squ^re method based on least squares method. Finally, the paper discussed the advantages and disadvantages through the example analysis of two kinds of linear data fitting method, and given reasonable control conditions for its application.展开更多
Network Coding (NC) brings correlation between the coded signals from different sources, which makes the system more vulnerable to the decode error at relay. Conventional Cyclic Redundancy Code (CRC) has been implemen...Network Coding (NC) brings correlation between the coded signals from different sources, which makes the system more vulnerable to the decode error at relay. Conventional Cyclic Redundancy Code (CRC) has been implemented for error bit detection. However, its error correction is simply ignored. To fully exploit this feature, this paper proposes a novel joint Log-Likelihood Ratio (LLR) CRC error mitigation for NC two way relay channel. Specific thresholds are designed to estimate the error number of data block and identify those which can be recovered if the number is within the error correction scope of CRC. We examine two modes of the thresholds, one based on the average Bit Error Rate (BER) of source-relay link, while the other based on that of instantaneous one. We provide the full analysis for the Pair-wise Error Probability (PEP) performance of the scheme. A variety of numerical results are presented to reveal the superiority of the proposed scheme to conventional CRC NC under independent Rayleigh fading channels. Moreover, the efficiencies of the proposed thresholds are also validated.展开更多
Based on experiment modal analysis(EMA) and operation modal analysis(OMA), the dynamic characteristics of cylindrical grinding machine were measured and provided a basis for further failure analysis.The influences of ...Based on experiment modal analysis(EMA) and operation modal analysis(OMA), the dynamic characteristics of cylindrical grinding machine were measured and provided a basis for further failure analysis.The influences of grinding parameters on dynamic characteristics were studied by analyzing the diagnostic signals extracted from racing and grinding experiments.The significant frequency of 38 Hz related to grinding wheel spindle speed of 2 307 r/min showed that the wheel spindle system was in a state of imbalan...展开更多
基金Project (50874056) supported by the National Natural Science Foundation of China
文摘Cu,Cu-2.2%Al and Cu-4.5%Al with stacking fault energies（SFE） of 78,35 and 7 mJ/m2 respectively were processed by cold-rolling（CR） at liquid nitrogen temperature（77 K） after hot-rolling.X-ray diffraction measurements indicate that a decrease in SFE leads to a decrease in crystallite size but increase in microstrain,dislocation and twin densities of the CR processed samples.Tensile tests at room temperature indicate that as the stacking fault energy decreases,the strength and ductility increase.The results indicate that decreasing stacking fault energy is an optimum method to improve the ductility without loss of strength.
文摘Pressure drops and heat transfer over staggered pin fin heat sinks with top bypass flow were experimentally evaluated. The authors considered liquid-cooling applications because there were few data available comparing to air-cooling applications. Empirical equations to predict heat transfer on the endwall were developed by obtaining experimental data on the copper base plate with acrylic pins. A new model for predicting pressure drops and heat transfer over staggered pin fin heat sinks with top bypass flow based on mass, momentum, and energy conservation within the two control volumes is proposed. The first control volume in the model is located within the finned area, and the second is located in the gap between the tip of the pins and the flow channel. This model combines two conditions according to the boundary-layer thickness. A comparison between experimental and calculated results revealed that dimensionless pressure drops and the Nusselt number could be predicted within 30% error for the former and 50% error for the latter.
基金Supported by the State Key Development Program for Basic Research of China(2003CB615705)
文摘Experimental investigation of the microfiltration （MF） using a revolving cross-flow membrane filter was performed under the condition of constant pressure difference, and different flat membranes made of polyvinylidene fluoride （PVDF, 0.1 μm）, cellulose acetate （CA, 0.22 μm）, sulfonated polyethersulfone （SPES, 0.22 μm） and polyamide （PA, 0.45 μm）, respectively, were used in filtration experiments. The dependence of the filtrate mass of the cross-flow MF on time was measured on-line. The experimental results showed that the effect of the cross-flow on high viscosity medium was more significant than that on the low viscosity one.
基金funded by the National Natural Science Foundation of China(41104049)the Earthquake Situation Tracking,CEA(2012020207)Scientific Investigation of Yushu M S 7.1 Earthquake,CEA(2060302)
文摘Using the results of aftershock relocation, inversion on seismic waves and InSAR results, and surface rupture displacements obtained by geological survey after the earthquake, this paper constructs a fault model of the Yushu Ms7. 1 earthquake. Based on rectangular dislocation theory in an elastic-viscoelastic layered medium, we have simulated the co- seismic deformation and gravity change with gravitational effect considered. The pictures show that the absolute gravity measuring point is beside the extremum of coseismic gravity change, and the numerical value reaches 25.02 x 10-Sm. s-2. After a discussion about the gravity changes before the earthquake and the coherence consistency between two FG-5 absolute gravimeters, we think that the measured value 27.2 × 10^-8 m· s^-2 at Yushu station is coseismic gravity change. It＇s coincident with the simulation results based on dislocation theory. Therefore it is a good tool to test the near-field changes found by dislocation theory.
文摘By using the method of least square linear fitting to analyze data do not exist errors under certain conditions, in order to make the linear data fitting method that can more accurately solve the relationship expression between the volume and quantity in scientific experiments and engineering practice, this article analyzed data error by commonly linear data fitting method, and proposed improved process of the least distance squ^re method based on least squares method. Finally, the paper discussed the advantages and disadvantages through the example analysis of two kinds of linear data fitting method, and given reasonable control conditions for its application.
基金Supported by the National 973 Programs (2013CB329104)the National Natural Science Foundations of China (No. 61071090, No. 61171093)+3 种基金the Postgraduate Innovation Programs of Scientific Research of Jiangsu Province (CXZZ11_0388)Jiangsu Province Natural Science Foundation Key Projects (11KJA510001)National Science and Technology Key Projects (2011ZX03005-004-003)Jiangsu 973 Projects (BK2011027)
文摘Network Coding (NC) brings correlation between the coded signals from different sources, which makes the system more vulnerable to the decode error at relay. Conventional Cyclic Redundancy Code (CRC) has been implemented for error bit detection. However, its error correction is simply ignored. To fully exploit this feature, this paper proposes a novel joint Log-Likelihood Ratio (LLR) CRC error mitigation for NC two way relay channel. Specific thresholds are designed to estimate the error number of data block and identify those which can be recovered if the number is within the error correction scope of CRC. We examine two modes of the thresholds, one based on the average Bit Error Rate (BER) of source-relay link, while the other based on that of instantaneous one. We provide the full analysis for the Pair-wise Error Probability (PEP) performance of the scheme. A variety of numerical results are presented to reveal the superiority of the proposed scheme to conventional CRC NC under independent Rayleigh fading channels. Moreover, the efficiencies of the proposed thresholds are also validated.
文摘Based on experiment modal analysis(EMA) and operation modal analysis(OMA), the dynamic characteristics of cylindrical grinding machine were measured and provided a basis for further failure analysis.The influences of grinding parameters on dynamic characteristics were studied by analyzing the diagnostic signals extracted from racing and grinding experiments.The significant frequency of 38 Hz related to grinding wheel spindle speed of 2 307 r/min showed that the wheel spindle system was in a state of imbalan...
