Recently,there has been a huge increase in the usage of fuel resources for automobiles which is severely affecting the climate and causing global warming.The use of electric vehicle(EV)is an effective way to protect t...Recently,there has been a huge increase in the usage of fuel resources for automobiles which is severely affecting the climate and causing global warming.The use of electric vehicle(EV)is an effective way to protect the environment and reduce travel costs.However,the EV charging system has a single charging source,and the charging rate is limited.In this paper,an EV wireless charging system based on dual source power supply has been developed.It realizes intelligent switching between 12 V photovoltaic output and 220 V AC dual source power,and has wireless transmission function.Based on the proposed power supply architecture,the micro wireless charging model is built,which enables the EV model to store power and realize static and mobile control through the wireless induction charging system.展开更多
Worldwide competition and diverse demand of customers pose great challenges to manufacturing enterprises. How to organize production to achieve high productivity and low cost becomes their primary task. In the mean ti...Worldwide competition and diverse demand of customers pose great challenges to manufacturing enterprises. How to organize production to achieve high productivity and low cost becomes their primary task. In the mean time, the rapid pace of technology innovation has contributed to the development of new types of flexible automation. Hence, increasing manufacturing enterprises convert to multi-product and small-batch production, a manufacturing strategy that brings increased output, reduced costs, and quick response to the market. A distinctive feature of small-batch production is that the system operates mainly in the transient states. Transient states may have a significant impact on manufacturing systems. It is therefore necessary to estimate the dynamic performance of systems. As the assembly system is a typical class of production systems, in this paper, we focus on the problem of dynamic performance prediction of the assembly systems that produce small batches of different types of products. And the system is assumed to be characterized with Bernoulli reliability machines, finite buffers, and changeovers. A mathematical model based on Markovian analysis is first derived and then, the analytical formulas for performance evaluation of three-machine assembly systems are given. Moreover, a novel approach based on decomposition and aggregation is proposed to predict dynamic performance of large-scale assembly systems that consist of multiple component lines and additional processing machines located downstream of the assemble machine. The proposed approach is validated to be highly accurate and computationally efficient when compared to Monte Carlo simulation.展开更多
Sterility changeover induced by low temperature in male sterility line CMS7311 of heading Chinese cabbage ( Brassica campestris L. ssp. penkinsis) was investigated under constant temperature, day/night alternating tem...Sterility changeover induced by low temperature in male sterility line CMS7311 of heading Chinese cabbage ( Brassica campestris L. ssp. penkinsis) was investigated under constant temperature, day/night alternating temperature in light-growth-incubator and outdoor natural day/night alternating temperature respectively. It showed that the sterility of CMS7311 has significant change with temperature. The constant temperature of 6 - 12 degreesC was suitable to induce the changeover of sterility (CGS) of CMS7311 ; the shortest treatment time for CGS induction at this temperature was 3 d. The significant value of sterility changeover of CMS7311 occurred at the constant temperature of 6 - 9 degreesC after treatment for 6 - 9 d. The intensity of CGS was stronger under constant temperature than under alternate temperature, but the shortest treatment time inducing CGS has no difference between them. When treated for 9 d under the day/night alternating temperature of 11/7 degreesC, its sterility could also turn to normal fertility (near to sterile grade I or zero). In normal condition, the interval from the end of temperature treatment to the beginning of CGS induction was 10 - 16 d. In the condition of natural day/night alternating temperature, the lower limit of temperature for effective CGS induction was at the daily mean temperature ( DMT) of 3. 5 - 6. 8 degreesC, and the shortest treatment time which could induce the sterility changeover was also longer than that under constant temperature, being 11d at DMT of 1.5 - 3.1 degreesC. In addition, for the apical dominance, the flower bud on the first lateral branch showed the CGS 8 - 10 d later than the flower bud on the main stem under the same temperature with the same days of treatment. The intensity of CGS of CMS7311 on the first lateral branch was also weaker than the flower bud on the main stem.展开更多
With the increase of style variation, decrease of lot size and shortening of lead-time, production planning becomes a big problem in clothing industry. It was found that changeover cost is one of key factors in garmen...With the increase of style variation, decrease of lot size and shortening of lead-time, production planning becomes a big problem in clothing industry. It was found that changeover cost is one of key factors in garment production. In this paper, based on time measurement and the data collected, considering the relevent elements such as previous experience, lot size, number of lines,the effect of changeover cost on garment production is calculated and analyzed. Then some suggestions are put forward for manufacturers to balance their production planning.展开更多
The Arab political transformations originally occurring in early 2011 are posing negative impact over China’s overseas interests in the Middle East region,including those related to its trade with the Arab world,the ...The Arab political transformations originally occurring in early 2011 are posing negative impact over China’s overseas interests in the Middle East region,including those related to its trade with the Arab world,the China-Middle East bilateral investments,its contracted projects,and the safety of its nationals living in the Middle East,whether these influences are direct or indirect,overt or covert.Three aspects are strongly impacted by these negative influences:1)Libya;2)Northern and southern Sudan;3)Energy supply.The dramatic changes of the Arab world have brought alerting signals to China over its national interests in the Middle East,so China shall undertake a meticulous review of its overseas activities and draw the correct lessons from its experiences there so that practical responses can be worked out.In consideration of the loss that Chinese corporations have suffered from the Arab political changeovers,China should establish its own grand strategy for its foreign relations so as to protect its growing overseas interests.展开更多
The boiling behavior of the liquid nitrogen (LN2) under the transient high heat flux urgently needs to be researched systematically. In this paper, the high power short pulse duration laser was used to heat the satura...The boiling behavior of the liquid nitrogen (LN2) under the transient high heat flux urgently needs to be researched systematically. In this paper, the high power short pulse duration laser was used to heat the saturated LN2 rapidly, and the high-speed photography aided by the spark light system was employed to take series of photos which displayed the process of LN2's boiling behavior under such conditions. Also, a special temperature measuring system was applied to record the temperature variation of the heating surface. The experiments indicated that an explosive boiling happened within LN2 by the laser heating, and a conventional boiling followed up after the newly-defined changeover time. By analyzing the temperature variation of the heating surface, it is found that the latent heat released by the crack of the bubbles in the bubble cluster induced by the explosive boiling is an important factor that greatly influences the boiling heat transfer mechanism.展开更多
An analysis related to the transport of nanofluid that is confined in a channel between two orthogonal permeable walls will be investigated with the help of two numerical techniques.With the aid of the reasonable simi...An analysis related to the transport of nanofluid that is confined in a channel between two orthogonal permeable walls will be investigated with the help of two numerical techniques.With the aid of the reasonable similarity changeover;the said model will be shaped into the desired non-linear equation whose behavior will be explained analytically as well as graphically where the functioning of three disparate variables such as magnetic parameter,permeable Reynold number,and channel permeable ratio will be explained precisely.The said model has been controlled by the homotopy analysis method(HAM)and then,compared through an efficient numerical method named shooting method(ShM).The profiles show that increases in the magnetic parameter decline the nanofluid flow velocity,whereas magnitude-wise raise is shown in each axial velocity profile.The radial profile raises while getting variation in wall expansion parameter from negative to positive.For the entire domain,the rate of change in velocity description enhances at the center while reduces at the surfaces.And the outcomes disclose that the wall permeable ratio has a significant impact on the solutions.Since the zero value of wall ratio refers to the particular type that Terrill has discussed.展开更多
基金supported in part by the National Natural Science Foundation of China(No.62371233)in part by the Aviation Science Foundation Project(Nos.2022Z024052003,20230058052001)。
文摘Recently,there has been a huge increase in the usage of fuel resources for automobiles which is severely affecting the climate and causing global warming.The use of electric vehicle(EV)is an effective way to protect the environment and reduce travel costs.However,the EV charging system has a single charging source,and the charging rate is limited.In this paper,an EV wireless charging system based on dual source power supply has been developed.It realizes intelligent switching between 12 V photovoltaic output and 220 V AC dual source power,and has wireless transmission function.Based on the proposed power supply architecture,the micro wireless charging model is built,which enables the EV model to store power and realize static and mobile control through the wireless induction charging system.
基金This work was supported in part by the National Key R&D Program of China(No.2021YFB1714800)the National Natural Science Foundation of China(No.62103042)the Beijing Municipal Natural Science Foundation(No.4214076).
文摘Worldwide competition and diverse demand of customers pose great challenges to manufacturing enterprises. How to organize production to achieve high productivity and low cost becomes their primary task. In the mean time, the rapid pace of technology innovation has contributed to the development of new types of flexible automation. Hence, increasing manufacturing enterprises convert to multi-product and small-batch production, a manufacturing strategy that brings increased output, reduced costs, and quick response to the market. A distinctive feature of small-batch production is that the system operates mainly in the transient states. Transient states may have a significant impact on manufacturing systems. It is therefore necessary to estimate the dynamic performance of systems. As the assembly system is a typical class of production systems, in this paper, we focus on the problem of dynamic performance prediction of the assembly systems that produce small batches of different types of products. And the system is assumed to be characterized with Bernoulli reliability machines, finite buffers, and changeovers. A mathematical model based on Markovian analysis is first derived and then, the analytical formulas for performance evaluation of three-machine assembly systems are given. Moreover, a novel approach based on decomposition and aggregation is proposed to predict dynamic performance of large-scale assembly systems that consist of multiple component lines and additional processing machines located downstream of the assemble machine. The proposed approach is validated to be highly accurate and computationally efficient when compared to Monte Carlo simulation.
文摘Sterility changeover induced by low temperature in male sterility line CMS7311 of heading Chinese cabbage ( Brassica campestris L. ssp. penkinsis) was investigated under constant temperature, day/night alternating temperature in light-growth-incubator and outdoor natural day/night alternating temperature respectively. It showed that the sterility of CMS7311 has significant change with temperature. The constant temperature of 6 - 12 degreesC was suitable to induce the changeover of sterility (CGS) of CMS7311 ; the shortest treatment time for CGS induction at this temperature was 3 d. The significant value of sterility changeover of CMS7311 occurred at the constant temperature of 6 - 9 degreesC after treatment for 6 - 9 d. The intensity of CGS was stronger under constant temperature than under alternate temperature, but the shortest treatment time inducing CGS has no difference between them. When treated for 9 d under the day/night alternating temperature of 11/7 degreesC, its sterility could also turn to normal fertility (near to sterile grade I or zero). In normal condition, the interval from the end of temperature treatment to the beginning of CGS induction was 10 - 16 d. In the condition of natural day/night alternating temperature, the lower limit of temperature for effective CGS induction was at the daily mean temperature ( DMT) of 3. 5 - 6. 8 degreesC, and the shortest treatment time which could induce the sterility changeover was also longer than that under constant temperature, being 11d at DMT of 1.5 - 3.1 degreesC. In addition, for the apical dominance, the flower bud on the first lateral branch showed the CGS 8 - 10 d later than the flower bud on the main stem under the same temperature with the same days of treatment. The intensity of CGS of CMS7311 on the first lateral branch was also weaker than the flower bud on the main stem.
文摘With the increase of style variation, decrease of lot size and shortening of lead-time, production planning becomes a big problem in clothing industry. It was found that changeover cost is one of key factors in garment production. In this paper, based on time measurement and the data collected, considering the relevent elements such as previous experience, lot size, number of lines,the effect of changeover cost on garment production is calculated and analyzed. Then some suggestions are put forward for manufacturers to balance their production planning.
文摘The Arab political transformations originally occurring in early 2011 are posing negative impact over China’s overseas interests in the Middle East region,including those related to its trade with the Arab world,the China-Middle East bilateral investments,its contracted projects,and the safety of its nationals living in the Middle East,whether these influences are direct or indirect,overt or covert.Three aspects are strongly impacted by these negative influences:1)Libya;2)Northern and southern Sudan;3)Energy supply.The dramatic changes of the Arab world have brought alerting signals to China over its national interests in the Middle East,so China shall undertake a meticulous review of its overseas activities and draw the correct lessons from its experiences there so that practical responses can be worked out.In consideration of the loss that Chinese corporations have suffered from the Arab political changeovers,China should establish its own grand strategy for its foreign relations so as to protect its growing overseas interests.
文摘The boiling behavior of the liquid nitrogen (LN2) under the transient high heat flux urgently needs to be researched systematically. In this paper, the high power short pulse duration laser was used to heat the saturated LN2 rapidly, and the high-speed photography aided by the spark light system was employed to take series of photos which displayed the process of LN2's boiling behavior under such conditions. Also, a special temperature measuring system was applied to record the temperature variation of the heating surface. The experiments indicated that an explosive boiling happened within LN2 by the laser heating, and a conventional boiling followed up after the newly-defined changeover time. By analyzing the temperature variation of the heating surface, it is found that the latent heat released by the crack of the bubbles in the bubble cluster induced by the explosive boiling is an important factor that greatly influences the boiling heat transfer mechanism.
文摘An analysis related to the transport of nanofluid that is confined in a channel between two orthogonal permeable walls will be investigated with the help of two numerical techniques.With the aid of the reasonable similarity changeover;the said model will be shaped into the desired non-linear equation whose behavior will be explained analytically as well as graphically where the functioning of three disparate variables such as magnetic parameter,permeable Reynold number,and channel permeable ratio will be explained precisely.The said model has been controlled by the homotopy analysis method(HAM)and then,compared through an efficient numerical method named shooting method(ShM).The profiles show that increases in the magnetic parameter decline the nanofluid flow velocity,whereas magnitude-wise raise is shown in each axial velocity profile.The radial profile raises while getting variation in wall expansion parameter from negative to positive.For the entire domain,the rate of change in velocity description enhances at the center while reduces at the surfaces.And the outcomes disclose that the wall permeable ratio has a significant impact on the solutions.Since the zero value of wall ratio refers to the particular type that Terrill has discussed.