To clarify the effects of ferrite morphologies and contents on high-cycle fatigue property of pearlite-ferrite dual-phase(DP)steel used for fabrication of commercial vehicle crankshafts,two types of DP steels with dif...To clarify the effects of ferrite morphologies and contents on high-cycle fatigue property of pearlite-ferrite dual-phase(DP)steel used for fabrication of commercial vehicle crankshafts,two types of DP steels with different ferrite grain sizes(S10:13.1μm and S30:21.4μm)and ferrite contents(S10:~9.5 vol.%and S30:~30.4 vol.%)were prepared.Stress amplitude-logarithm of number of high cycles to failure fatigue of the two DP steels was evaluated.Experimental results showed a fatigue strength of 510 and 400 MPa for S10 and S30 steels,respectively,at 10^(7) cycles.Fatigue cracks in S10 steel extended preferentially along the grain boundary,but it was easy for crack propagation to extend within a pearlite colony to form a zigzag crack morphology.Crack roughness was enhanced and high stress was introduced to the crack surface due to this kind of crack propagation behavior,which has positive effects on slowing down crack propagation.However,the crack propagation in S30 steel mainly occurred inside the soft equiaxed coarse ferrite grain.Analysis revealed that little stress was introduced to the crack surface.These results show that it is possible to improve high cycle fatigue strength of pearlite-ferrite DP steel by appropriately manipulating the volume fraction and microstructure morphology of ferrite phase.展开更多
The problem of H∞ stability analysis and control synthesis of switched systems with delayed states under arb/trary switchirg laws is considered. By means of Lyapunov function and linear matrix inequality tools, suffi...The problem of H∞ stability analysis and control synthesis of switched systems with delayed states under arb/trary switchirg laws is considered. By means of Lyapunov function and linear matrix inequality tools, sufficient ctmdition of H∞ stability is presented in terms of linear matrix inequalities. Furthermore, the robust H∞ control synthesis via state feedback and output feedack is studied. Finally, a numerical example is given to demonstrate the effectiveness of the proposed method.展开更多
Technology gives many oppurtunites for cattle farmers for easier and effective herd management possibilities. New era provides many realistic applications using smart applications for farmers. Especially milking is ve...Technology gives many oppurtunites for cattle farmers for easier and effective herd management possibilities. New era provides many realistic applications using smart applications for farmers. Especially milking is very popular for engineering applications. Reproductive technologies can be seen as frontier applications. Reproductive performances of the dairy farms can be defined as number of calves for cows in a year. It means new material for meat and milk production. Because new female calf means new cow for her while male calf means new material for beef. If meat and milk production are to be increased, cow productivity, i.e. the number of calves produced lifetime must be improved and increased. Although varying among herds, annual average herd incidences of reproductive disorders and reproductive performance were similar to those reported. Managerial practices influenced incidences of retained placenta and uterine infection, days open of cows not bred and of all cows, services per conception and percentages of herd open more than 100 days and culled for low production. Good heat detection programs can have a major impact on overall herd reproductive performance. The best heat detection programs start with careful timing, good observation and the effective use of detection aids. Being able to distinguish and interpret cow behaviour and other signs is critical, so are good record keeping and training for the people responsible for heat detection. Generaly, farmers with the best heat detection results use a combination of observation and heat detection aids. Several options are available to aid heat detection and increase heat detection rates. Although a rich variety of methods have been introduced for the detection of oestrus, a more accurate and practical method is still required.展开更多
The Olkaria geothermal field is located in the Kenyan Rift valley, about 120 km from Nairobi. Development of geothermal resources in the Olkaria area, a high temperature field, started in the early 1950s. In the subse...The Olkaria geothermal field is located in the Kenyan Rift valley, about 120 km from Nairobi. Development of geothermal resources in the Olkaria area, a high temperature field, started in the early 1950s. In the subsequent years numerous expansions have been carried out with additional power plants being installed in Olkaria. These include a binary plant at Olkaria South West (Olkaria III) in 2000, a condensing plant at Olkaria North East (Olkaria II) in 2003, another binary plant at Olkaria North West (Oserian) in 2004 and finally condensing plants in the year 2014 within East production field (EPF) and Olkaria Domes (OD) areas. The total generation from this field is about 730 Mw. The study considered samples from 4 producing wells from 3 fields of the Olkaria geothermal area (OW-44 from the Olkaria East, OW-724A from the Olkaria North East, and OW-914 and OW-915 from the Olkaria Domes field). The chemical data were first analyzed using SOLVEQ. This helped in the determination of the equilibrium state of the system, the reservoir temperatures and the total moles to be run through CHILLER. The run CHILLER considered the processes that have been proven to be occurring in the Olkaria field i.e., boiling and condensing processes, fluid-fluid mixing rocks and titration resulting from water-rock interaction. The effects on gas evolution were evaluated based on the resulting recalculated gas pressures. The results indicate that the gas species are not in equilibrium with the mineral assemblages. The CHILLER evaluation shows boiling as the major process leading to the evolution of gases. OW-44 had the least gas concentrations, arising from the considered reservoir processes due to degassing, and near surface boiling, besides the removal of NH<sub>3</sub>, H<sub>2</sub> and H<sub>2</sub>S are through the reaction with steam condensate. The gas breakout is most likely in OW-914 and least in OW-44. The study proposes different reservoir management strategies for the different parts of the Olkaria geothermal field. That is by increasing hot reinjection in the eastern sector around well OW-44. The reservoir around OW-914 is to be managed by operating the wells at a minimum flow rate (or even to close them) or the use of chemical inhibitors to prevent calcite scaling.展开更多
The current existed scheduling schemes which are generally derived from the antenna selection algorithms can improve the sum-rate of MU-MIMO system to some extent.However,these schemes can not make the best of multi-u...The current existed scheduling schemes which are generally derived from the antenna selection algorithms can improve the sum-rate of MU-MIMO system to some extent.However,these schemes can not make the best of multi-user diversity gain,thus incurring capacity loss.To overcome these disadvantages,in this paper,a novel user scheduling scheme based on the lower bound capacity of MU-MIMO broadcast channel is proposed for the multi-user zero-forcing precoding system.In the proposed scheme,the base station will schedule those users that can achieve the maximal lower bound capacity of MU-MIMO system by certain optimal criterion.Simulation results are exhibited to indicate that the proposed scheme can provide performance improvement than other existed scheduling schemes.展开更多
The feasibility of the nozzle of self-excited oscillation pulsed jet (SEOPJ) as the breaker and loosing device for the air-lift pump was researched.The dynamic characteris- tics of the SEOPJ to crush the hard clay and...The feasibility of the nozzle of self-excited oscillation pulsed jet (SEOPJ) as the breaker and loosing device for the air-lift pump was researched.The dynamic characteris- tics of the SEOPJ to crush the hard clay and loose the layer of ore deposit were explored experimentally under the submerged condition.The results show that the SEOPJ not only effectively breaks the hard clay or loose the particles of sand on the placer bed,but also produces fluctuating uplift force acting on particles of sand.The oscillating cross flow caused by the SEOPJ makes particles of sand move to the end of the suction pipe easily. Energy efficency of the airlift and concentration of the solids for the solid-liquid mixture sucked by the air-lift pump are increased obviously with the breaker of SEOPJ.展开更多
In order to facilitate the development of China's market economy and responsethe competition in the post-WTO era, it is important for China national business organizations topursue performance excellence. Accordin...In order to facilitate the development of China's market economy and responsethe competition in the post-WTO era, it is important for China national business organizations topursue performance excellence. According to related requirements of the Law of the People's Republicof China on Product Quality and the Quality Improvement Approach issued by China State Council, theCriteria for Performance Excellence was developed in order to guide organizations to pursueperformance excellence and improve the quality of products, service and business. On the basis ofthe national quality award criteria in other countries and the quality management practice in China,this national standard specifies the performance excellence evaluation requirements oforganizations in 7 aspects, which are leadership, strategy, customers and market, resources, processmanagement, measurement, analysis, improvement and business results. The national standard providesorganizations with self-assessment criteria to pursue performance excellence, and it can also beused as evaluating criteria of quality award.展开更多
基金supported from BAOSTEEL-SJTU Joint Research Center for Future Steelgrateful to the financial support from Startup Fund for Youngman Research at SJTU(SFYR at SJTU).
文摘To clarify the effects of ferrite morphologies and contents on high-cycle fatigue property of pearlite-ferrite dual-phase(DP)steel used for fabrication of commercial vehicle crankshafts,two types of DP steels with different ferrite grain sizes(S10:13.1μm and S30:21.4μm)and ferrite contents(S10:~9.5 vol.%and S30:~30.4 vol.%)were prepared.Stress amplitude-logarithm of number of high cycles to failure fatigue of the two DP steels was evaluated.Experimental results showed a fatigue strength of 510 and 400 MPa for S10 and S30 steels,respectively,at 10^(7) cycles.Fatigue cracks in S10 steel extended preferentially along the grain boundary,but it was easy for crack propagation to extend within a pearlite colony to form a zigzag crack morphology.Crack roughness was enhanced and high stress was introduced to the crack surface due to this kind of crack propagation behavior,which has positive effects on slowing down crack propagation.However,the crack propagation in S30 steel mainly occurred inside the soft equiaxed coarse ferrite grain.Analysis revealed that little stress was introduced to the crack surface.These results show that it is possible to improve high cycle fatigue strength of pearlite-ferrite DP steel by appropriately manipulating the volume fraction and microstructure morphology of ferrite phase.
基金supported by the National“863”Foundation of China under Grant 2007AA04Z193
文摘The problem of H∞ stability analysis and control synthesis of switched systems with delayed states under arb/trary switchirg laws is considered. By means of Lyapunov function and linear matrix inequality tools, sufficient ctmdition of H∞ stability is presented in terms of linear matrix inequalities. Furthermore, the robust H∞ control synthesis via state feedback and output feedack is studied. Finally, a numerical example is given to demonstrate the effectiveness of the proposed method.
文摘Technology gives many oppurtunites for cattle farmers for easier and effective herd management possibilities. New era provides many realistic applications using smart applications for farmers. Especially milking is very popular for engineering applications. Reproductive technologies can be seen as frontier applications. Reproductive performances of the dairy farms can be defined as number of calves for cows in a year. It means new material for meat and milk production. Because new female calf means new cow for her while male calf means new material for beef. If meat and milk production are to be increased, cow productivity, i.e. the number of calves produced lifetime must be improved and increased. Although varying among herds, annual average herd incidences of reproductive disorders and reproductive performance were similar to those reported. Managerial practices influenced incidences of retained placenta and uterine infection, days open of cows not bred and of all cows, services per conception and percentages of herd open more than 100 days and culled for low production. Good heat detection programs can have a major impact on overall herd reproductive performance. The best heat detection programs start with careful timing, good observation and the effective use of detection aids. Being able to distinguish and interpret cow behaviour and other signs is critical, so are good record keeping and training for the people responsible for heat detection. Generaly, farmers with the best heat detection results use a combination of observation and heat detection aids. Several options are available to aid heat detection and increase heat detection rates. Although a rich variety of methods have been introduced for the detection of oestrus, a more accurate and practical method is still required.
文摘The Olkaria geothermal field is located in the Kenyan Rift valley, about 120 km from Nairobi. Development of geothermal resources in the Olkaria area, a high temperature field, started in the early 1950s. In the subsequent years numerous expansions have been carried out with additional power plants being installed in Olkaria. These include a binary plant at Olkaria South West (Olkaria III) in 2000, a condensing plant at Olkaria North East (Olkaria II) in 2003, another binary plant at Olkaria North West (Oserian) in 2004 and finally condensing plants in the year 2014 within East production field (EPF) and Olkaria Domes (OD) areas. The total generation from this field is about 730 Mw. The study considered samples from 4 producing wells from 3 fields of the Olkaria geothermal area (OW-44 from the Olkaria East, OW-724A from the Olkaria North East, and OW-914 and OW-915 from the Olkaria Domes field). The chemical data were first analyzed using SOLVEQ. This helped in the determination of the equilibrium state of the system, the reservoir temperatures and the total moles to be run through CHILLER. The run CHILLER considered the processes that have been proven to be occurring in the Olkaria field i.e., boiling and condensing processes, fluid-fluid mixing rocks and titration resulting from water-rock interaction. The effects on gas evolution were evaluated based on the resulting recalculated gas pressures. The results indicate that the gas species are not in equilibrium with the mineral assemblages. The CHILLER evaluation shows boiling as the major process leading to the evolution of gases. OW-44 had the least gas concentrations, arising from the considered reservoir processes due to degassing, and near surface boiling, besides the removal of NH<sub>3</sub>, H<sub>2</sub> and H<sub>2</sub>S are through the reaction with steam condensate. The gas breakout is most likely in OW-914 and least in OW-44. The study proposes different reservoir management strategies for the different parts of the Olkaria geothermal field. That is by increasing hot reinjection in the eastern sector around well OW-44. The reservoir around OW-914 is to be managed by operating the wells at a minimum flow rate (or even to close them) or the use of chemical inhibitors to prevent calcite scaling.
基金Sponsored by the Important National Science & Technology Specific Projects of China (Grant No. 2009ZX03004-001)the Cooperation Project with Huawei Technologies Company (Grant No. YBWL2010242)
文摘The current existed scheduling schemes which are generally derived from the antenna selection algorithms can improve the sum-rate of MU-MIMO system to some extent.However,these schemes can not make the best of multi-user diversity gain,thus incurring capacity loss.To overcome these disadvantages,in this paper,a novel user scheduling scheme based on the lower bound capacity of MU-MIMO broadcast channel is proposed for the multi-user zero-forcing precoding system.In the proposed scheme,the base station will schedule those users that can achieve the maximal lower bound capacity of MU-MIMO system by certain optimal criterion.Simulation results are exhibited to indicate that the proposed scheme can provide performance improvement than other existed scheduling schemes.
基金the National Natural Science Foundation(50504021)the Key Science and Technology Project of National Education Ministry(206122)the Science and Technology Project of Chongqing Education Committee(KJ070419)
文摘The feasibility of the nozzle of self-excited oscillation pulsed jet (SEOPJ) as the breaker and loosing device for the air-lift pump was researched.The dynamic characteris- tics of the SEOPJ to crush the hard clay and loose the layer of ore deposit were explored experimentally under the submerged condition.The results show that the SEOPJ not only effectively breaks the hard clay or loose the particles of sand on the placer bed,but also produces fluctuating uplift force acting on particles of sand.The oscillating cross flow caused by the SEOPJ makes particles of sand move to the end of the suction pipe easily. Energy efficency of the airlift and concentration of the solids for the solid-liquid mixture sucked by the air-lift pump are increased obviously with the breaker of SEOPJ.
文摘In order to facilitate the development of China's market economy and responsethe competition in the post-WTO era, it is important for China national business organizations topursue performance excellence. According to related requirements of the Law of the People's Republicof China on Product Quality and the Quality Improvement Approach issued by China State Council, theCriteria for Performance Excellence was developed in order to guide organizations to pursueperformance excellence and improve the quality of products, service and business. On the basis ofthe national quality award criteria in other countries and the quality management practice in China,this national standard specifies the performance excellence evaluation requirements oforganizations in 7 aspects, which are leadership, strategy, customers and market, resources, processmanagement, measurement, analysis, improvement and business results. The national standard providesorganizations with self-assessment criteria to pursue performance excellence, and it can also beused as evaluating criteria of quality award.
