Dispersion-strengthened copper (DSC) with WC as dispersoid was prepared bymeans of mechanical alloying (MA) following the traditional powder metallurgy (P/M) route. Influenceof WC content on the properties of material...Dispersion-strengthened copper (DSC) with WC as dispersoid was prepared bymeans of mechanical alloying (MA) following the traditional powder metallurgy (P/M) route. Influenceof WC content on the properties of material was discussed in detail, and result shows that when thevolume fraction of WC is 1.6%, the material achieves the best overall property, and a little moreparticle addition led to a less superior property owing to occurrence of particle agglomeration. Theas-sintered composite was designed to undergo a deformation of 75%. It is proved that appropriatedeformation is helpful to attain a higher density and consequently better properties. Deformedmaterial was then exposed to elevated temperature to test its effect on material. Annealing for 1 hat 1173K caused material to recover quite completely, but no obvious recrystallization was observed.It's supposed the particles handicaps motion of dislocations and material demonstrates goodretention of strength with substantial improvement in elongation.展开更多
Five kinds of WSi_2/MoSi_2 composites were successfully prepared bymechanical alloying, IP and high temperature sintering techniques. And their hardness and fracturetoughness were measured by the Vickers indentation f...Five kinds of WSi_2/MoSi_2 composites were successfully prepared bymechanical alloying, IP and high temperature sintering techniques. And their hardness and fracturetoughness were measured by the Vickers indentation fracture mode through an Hv-10A type sclerometer.The microstructure and morphology were investigated by a JSM-56001V scanning electron microscope.Results show that the addition of 50% WSi_2 (in mole fraction) has remarkable hardening andtoughening effects on the MoSi_2 matrix, whose hardness value and fracture toughness value areincreased about 60% and 86%, respectively. For WSi_2/MoSi_2 composite, the hardening mechanisms arefine-grain and the second phase particles strengthening, and the toughening mechanisms includefine-grain, grain drawing, crack deflection, microbridge and bowing toughening.展开更多
Comparing the online monitoring data of Qilihai with the manual testing data in the laboratory, the results show that the trends of the two are consistent;Monitoring data analysts should fully consider the relationshi...Comparing the online monitoring data of Qilihai with the manual testing data in the laboratory, the results show that the trends of the two are consistent;Monitoring data analysts should fully consider the relationship between various parameters and conduct a comprehensive analysis of water pollution. Through the application of online monitoring data, data analysis, water quality evaluation and pollutant flux calculation can be carried out, which should give full play to its role and influence in water quality monitoring.展开更多
A 32-bit pipeline accumulator with carry ripple topology is implemented for direct digital frequency synthesizer.To increase the throughout while hold down the area and power consumption,a method to reduce the number ...A 32-bit pipeline accumulator with carry ripple topology is implemented for direct digital frequency synthesizer.To increase the throughout while hold down the area and power consumption,a method to reduce the number of the pre-skewing registers is proposed.The number is reduced to 29% of a conventional pipeline accumulator.The propagation delay versus bias current of the adder circuit with different size transistors is investigated.We analyze the delay by employing the open circuit time constant method.Compared to the simulation results,the maximum error is less than 8%.A method to optimum the design of the adder based on the propagation delay is discussed.The clock traces for the 32-bit adder are heavily loaded,as there are 40 registers being connected to them.Moreover,the differential clock traces,which are much longer than the critical length,should be treated as transmission lines.Thus a clock distribution method and a termination scheme are proposed to get high quality and low skew clock signals.A multiple-type termination scheme is proposed to match the transmission line impedance.The 32-bit accumulator was measured to work functionally at 5.3 GHz.展开更多
文摘Dispersion-strengthened copper (DSC) with WC as dispersoid was prepared bymeans of mechanical alloying (MA) following the traditional powder metallurgy (P/M) route. Influenceof WC content on the properties of material was discussed in detail, and result shows that when thevolume fraction of WC is 1.6%, the material achieves the best overall property, and a little moreparticle addition led to a less superior property owing to occurrence of particle agglomeration. Theas-sintered composite was designed to undergo a deformation of 75%. It is proved that appropriatedeformation is helpful to attain a higher density and consequently better properties. Deformedmaterial was then exposed to elevated temperature to test its effect on material. Annealing for 1 hat 1173K caused material to recover quite completely, but no obvious recrystallization was observed.It's supposed the particles handicaps motion of dislocations and material demonstrates goodretention of strength with substantial improvement in elongation.
文摘Five kinds of WSi_2/MoSi_2 composites were successfully prepared bymechanical alloying, IP and high temperature sintering techniques. And their hardness and fracturetoughness were measured by the Vickers indentation fracture mode through an Hv-10A type sclerometer.The microstructure and morphology were investigated by a JSM-56001V scanning electron microscope.Results show that the addition of 50% WSi_2 (in mole fraction) has remarkable hardening andtoughening effects on the MoSi_2 matrix, whose hardness value and fracture toughness value areincreased about 60% and 86%, respectively. For WSi_2/MoSi_2 composite, the hardening mechanisms arefine-grain and the second phase particles strengthening, and the toughening mechanisms includefine-grain, grain drawing, crack deflection, microbridge and bowing toughening.
文摘Comparing the online monitoring data of Qilihai with the manual testing data in the laboratory, the results show that the trends of the two are consistent;Monitoring data analysts should fully consider the relationship between various parameters and conduct a comprehensive analysis of water pollution. Through the application of online monitoring data, data analysis, water quality evaluation and pollutant flux calculation can be carried out, which should give full play to its role and influence in water quality monitoring.
基金supported by the National Basic Research Program of China (2010CB327505)
文摘A 32-bit pipeline accumulator with carry ripple topology is implemented for direct digital frequency synthesizer.To increase the throughout while hold down the area and power consumption,a method to reduce the number of the pre-skewing registers is proposed.The number is reduced to 29% of a conventional pipeline accumulator.The propagation delay versus bias current of the adder circuit with different size transistors is investigated.We analyze the delay by employing the open circuit time constant method.Compared to the simulation results,the maximum error is less than 8%.A method to optimum the design of the adder based on the propagation delay is discussed.The clock traces for the 32-bit adder are heavily loaded,as there are 40 registers being connected to them.Moreover,the differential clock traces,which are much longer than the critical length,should be treated as transmission lines.Thus a clock distribution method and a termination scheme are proposed to get high quality and low skew clock signals.A multiple-type termination scheme is proposed to match the transmission line impedance.The 32-bit accumulator was measured to work functionally at 5.3 GHz.
