In the article the results of measurements of the resultant force in the legs of a powered roof support unit, caused by a dynamic interaction of the rock mass, are discussed. The measurements have been taken in the lo...In the article the results of measurements of the resultant force in the legs of a powered roof support unit, caused by a dynamic interaction of the rock mass, are discussed. The measurements have been taken in the longwalls mined with a roof fall, characterized by the highest degree of bumping hazard. It has been stated that the maximal force in the legs F m, recorded during a dynamic interaction of the rock mass, is proportional to the initial static force in the legs F st,p . Therefore a need for a careful selection of the initial load of the powered roof support, according to the local mining and geological conditions, results from such a statement. Setting the legs with the supporting load exceeding the indispensable value for keeping the direct roof solids in balance, deteriorating the operational parameters of a longwall system also has a disadvantageous influence on the value of the force in the legs and the rate of its increase, caused by a dynamic interaction of the rock mass. A correct selection of the initial load causes a decrease in the intensity of a dynamic interaction of the rock mass on powered roof supports, which also has an advantageous influence on their life. Simultaneously with the measurements of the resultant force in the legs, the vertical acceleration of the canopy was also recorded. It has enabled to prove that the external dynamic forces may act on the unit both from the roof as well as from the floor. The changes of the force in the legs caused by dynamic phenomena intrinsically created in the roof and changes of the force in the legs caused by blasting explosives in the roof of the working, have been analyzed separately. It has been stated that an increase in the loads of legs, caused by intrinsic phenomena is significantly higher than a force increase in the legs caused by blasting. It means that powered roof supports, to be operated in the workings, where the bumping hazard occurs, will also transmit the loads acting on a unit during blasting. The majority of recorded force changes in the legs has been caused by a dynamic interaction of the roof. They are characterized by a load increase coefficient K d, satisfying the inequality 1 06<K d =F m /F st,p <1 24. A much smaller number of cases, when the external load acted on the bases, was recorded. Individual, recorded results of measurements indicate that changes of the force in the legs, caused by external loads of this type, run more intensively due to roof loads (1 08< K d<1 80),particularly in these cases when the near the roof layer of the seam is under mining. A determination of more precise relations among the changes of forces in the legs, caused by a dynamic interaction of the floor and the bases and the mining and geological conditions requires a performance of additional underground tests.展开更多
Attention is concentrated on how to perform the innovative design during the process of pumping unit conceptual design, and how to enhance design efficiency and inspire creativity. Aiming at the shortages of conceptua...Attention is concentrated on how to perform the innovative design during the process of pumping unit conceptual design, and how to enhance design efficiency and inspire creativity. Aiming at the shortages of conceptual design, introducing the theory of inventive problem solving （TRIZ） into the mechanical product design for producing innovative ideas, and using the advanced computer-aided technique, the intelligent decision support system （IDSS） based on TRIZ （TRIZ-IDSS） has been constructed. The construction method, system structure, conceptual production, decisionmaking and evaluation of the problem solving subsystem are discussed. The innovative conceptual design of pumping units indicates that the system can help the engineers open up a new space of thinking, overcome the thinking inertia, and put forward innovative design concepts. This system also can offer the scientific instructions for the innovative design of mechanical products.展开更多
By the author denotes the areal measure on the unit disk . Let H'p = {f(z): f(z) is analytic in D and . Let B H 'p and. This article researches the support points and extreme points of B(H'p).
目的整合新生儿重症监护室(neonatal intensive care units,NICUs)住院早产儿发育支持护理的最佳证据,为临床医护人员提供规范化评估和管理早产儿发育支持护理的循证依据。方法在指南网站和中英文数据库中系统检索有关早产儿发育支持护...目的整合新生儿重症监护室(neonatal intensive care units,NICUs)住院早产儿发育支持护理的最佳证据,为临床医护人员提供规范化评估和管理早产儿发育支持护理的循证依据。方法在指南网站和中英文数据库中系统检索有关早产儿发育支持护理的指南、专家共识、证据总结、系统评价和Meta分析,检索时限为2013年1月—2023年10月。结果共纳入29篇文献,包括7篇指南、3篇专家共识、3篇证据总结以及16篇系统评价。从7个方面总结了36条最佳证据。结论本研究总结了NICU住院早产儿发育支持护理的最佳证据,为医护人员提供循证支持。在临床实际应用中,应结合具体的临床情景,以规范管理早产儿的发育支持护理。展开更多
文摘In the article the results of measurements of the resultant force in the legs of a powered roof support unit, caused by a dynamic interaction of the rock mass, are discussed. The measurements have been taken in the longwalls mined with a roof fall, characterized by the highest degree of bumping hazard. It has been stated that the maximal force in the legs F m, recorded during a dynamic interaction of the rock mass, is proportional to the initial static force in the legs F st,p . Therefore a need for a careful selection of the initial load of the powered roof support, according to the local mining and geological conditions, results from such a statement. Setting the legs with the supporting load exceeding the indispensable value for keeping the direct roof solids in balance, deteriorating the operational parameters of a longwall system also has a disadvantageous influence on the value of the force in the legs and the rate of its increase, caused by a dynamic interaction of the rock mass. A correct selection of the initial load causes a decrease in the intensity of a dynamic interaction of the rock mass on powered roof supports, which also has an advantageous influence on their life. Simultaneously with the measurements of the resultant force in the legs, the vertical acceleration of the canopy was also recorded. It has enabled to prove that the external dynamic forces may act on the unit both from the roof as well as from the floor. The changes of the force in the legs caused by dynamic phenomena intrinsically created in the roof and changes of the force in the legs caused by blasting explosives in the roof of the working, have been analyzed separately. It has been stated that an increase in the loads of legs, caused by intrinsic phenomena is significantly higher than a force increase in the legs caused by blasting. It means that powered roof supports, to be operated in the workings, where the bumping hazard occurs, will also transmit the loads acting on a unit during blasting. The majority of recorded force changes in the legs has been caused by a dynamic interaction of the roof. They are characterized by a load increase coefficient K d, satisfying the inequality 1 06<K d =F m /F st,p <1 24. A much smaller number of cases, when the external load acted on the bases, was recorded. Individual, recorded results of measurements indicate that changes of the force in the legs, caused by external loads of this type, run more intensively due to roof loads (1 08< K d<1 80),particularly in these cases when the near the roof layer of the seam is under mining. A determination of more precise relations among the changes of forces in the legs, caused by a dynamic interaction of the floor and the bases and the mining and geological conditions requires a performance of additional underground tests.
文摘Attention is concentrated on how to perform the innovative design during the process of pumping unit conceptual design, and how to enhance design efficiency and inspire creativity. Aiming at the shortages of conceptual design, introducing the theory of inventive problem solving （TRIZ） into the mechanical product design for producing innovative ideas, and using the advanced computer-aided technique, the intelligent decision support system （IDSS） based on TRIZ （TRIZ-IDSS） has been constructed. The construction method, system structure, conceptual production, decisionmaking and evaluation of the problem solving subsystem are discussed. The innovative conceptual design of pumping units indicates that the system can help the engineers open up a new space of thinking, overcome the thinking inertia, and put forward innovative design concepts. This system also can offer the scientific instructions for the innovative design of mechanical products.
文摘By the author denotes the areal measure on the unit disk . Let H'p = {f(z): f(z) is analytic in D and . Let B H 'p and. This article researches the support points and extreme points of B(H'p).
文摘目的整合新生儿重症监护室(neonatal intensive care units,NICUs)住院早产儿发育支持护理的最佳证据,为临床医护人员提供规范化评估和管理早产儿发育支持护理的循证依据。方法在指南网站和中英文数据库中系统检索有关早产儿发育支持护理的指南、专家共识、证据总结、系统评价和Meta分析,检索时限为2013年1月—2023年10月。结果共纳入29篇文献,包括7篇指南、3篇专家共识、3篇证据总结以及16篇系统评价。从7个方面总结了36条最佳证据。结论本研究总结了NICU住院早产儿发育支持护理的最佳证据,为医护人员提供循证支持。在临床实际应用中,应结合具体的临床情景,以规范管理早产儿的发育支持护理。
