Microcutting is a precision technology that offers flexible fabrication of microfeatures or complex three-dimensional components with high machining accuracy and superior surface quality.This technology may offer grea...Microcutting is a precision technology that offers flexible fabrication of microfeatures or complex three-dimensional components with high machining accuracy and superior surface quality.This technology may offer great potential as well as advantageous process capabilities for the machining of hard-to-cut materials,such as tungsten carbide.The geometrical design and dimension of the tool cutting edge is a key factor that determines the size and form accuracy possible in the machined workpiece.Currently,the majority of commercial microtools are scaled-down versions of conventional macrotool designs.This approach does not impart optimal performance due to size effects and associated phenomena.Consequently,in-depth analysis and implementation of microcutting mechanics and fundamentals are required to enable successful industrial adaptation in microtool design and fabrication methods.This paper serves as a review of recent microtool designs,materials,and fabrication methods.Analysis of tool performance is discussed,and new approaches and techniques are examined.Of particular focus is tool wear suppression in the machining of hard materials and associated process parameters,including internal cooling and surface patterning techniques.The review concludes with suggestions for an integrated design and fabrication process chain which can aid industrial microtool manufacture.展开更多
Infection Prevention and Control is a Quality Standard and is crucial in all health care facilities. Many hospitals remain deficient in trained infection control professionals (ICPs), and now there is an acute awarene...Infection Prevention and Control is a Quality Standard and is crucial in all health care facilities. Many hospitals remain deficient in trained infection control professionals (ICPs), and now there is an acute awareness of the need to correct this shortfall. The objectives of the study were to describe the current status of ICP programs at ministry of health (MOH) and to evaluate the current status of infection prevention and control programs at health care facilities in kingdom of Saudi Arabia. A cross sectional interview and a self assessment study were conducted on infection prevention and control (IPC) program in Saudi Arabia. All the MOH hospital in all regions was randomly chosen to the study setting. The selection of facilities was done at random with a clear intention to include twenty regions. A random sample was taken from these hospitals with sample size 56 (55.4%), by Multi stage random sampling technique. Results showed that the total facility in all over the kingdom was 51.4% where central area covered the facility score 58.2%, followed by western area (54.8%), south (53.7%), east (46.3%), and lastly with (45.8%) north area. Survey revealed that the infrastructure for infection control program in Saudi Arabian hospitals remained underdeveloped. There were defects in the identified components of effective infection control programs.展开更多
Accompanying the unceasing progress of integrated circuit manufacturing technology, the mainstream production mode of current semiconductor wafer fabrication is featured with multi-variety, small batch, and individual...Accompanying the unceasing progress of integrated circuit manufacturing technology, the mainstream production mode of current semiconductor wafer fabrication is featured with multi-variety, small batch, and individual customization, which poses a huge challenge to the scheduling of cluster tools with single-wafer-type fabrication. Concurrent processing multiple wafer types in cluster tools, as a novel production pattern, has drawn increasing attention from industry to academia, whereas the corresponding research remains insufficient. This paper investigates the scheduling problems of dual-arm cluster tools with multiple wafer types and residency time constraints. To pursue an easy-to-implement cyclic operation under diverse flow patterns,we develop a novel robot activity strategy called multiplex swap sequence. In the light of the virtual module technology, the workloads that stem from bottleneck process steps and asymmetrical process configuration are balanced satisfactorily. Moreover, several sufficient and necessary conditions with closed-form expressions are obtained for checking the system's schedulability. Finally, efficient algorithms with polynomial complexity are developed to find the periodic scheduling, and its practicability and availability are demonstrated by the offered illustrative examples.展开更多
Fuel cycle related activities were accomplished in IPEN-CNEN/SP in laboratory and pilot plant scale and most facilities were built in the 70-80 years. Nevertheless, radical changes of the Brazilian nuclear policy in t...Fuel cycle related activities were accomplished in IPEN-CNEN/SP in laboratory and pilot plant scale and most facilities were built in the 70-80 years. Nevertheless, radical changes of the Brazilian nuclear policy in the beginning of 90＇s determined the interruption of several fuel cycle activities and facilities shutdown. Some laboratory and pilot plant decommissioning activities have been performed in IPEN in the last years. During the operational activities in the decommissioning of old nuclear fuel cycle facilities, the personnel involved in the task had to face several problems. In old facilities, the need of large components dismantling and material removal use to present some difficulties, such as lack of available and near electricity supply. Besides this, the spread out of the superficial contamination in the form of dust or aerosols and the exposure of workers should be as much as possible avoided. Then, the selection and availability of suitable tools for the task, mainly those employed for cutting and segmentation of different materials is of significant importance. Slight hand tools, mainly those powered by rechargeable batteries, facilitate the work, especially in areas where the access is difficult. Based on the experience in the dismantling of some old nuclear facilities of IPEN-CNEN/SP, some tools that would have facilitated the operations were identified and their availability could have improved the quality and efficiency of different individual tasks. In this paper, different cutting problems and techniques, as well as some available commercial hand tools, are presented as suggestion for future activities.展开更多
基金supported by Science Foundation Ireland(No.15/RP/B3208)the National Natural Science Foundation of China(Nos.51320105009&61635008)the‘111’Project by the State Administration of Foreign Experts Affairs and the Ministry of Education of China(Grant No.B07014).
文摘Microcutting is a precision technology that offers flexible fabrication of microfeatures or complex three-dimensional components with high machining accuracy and superior surface quality.This technology may offer great potential as well as advantageous process capabilities for the machining of hard-to-cut materials,such as tungsten carbide.The geometrical design and dimension of the tool cutting edge is a key factor that determines the size and form accuracy possible in the machined workpiece.Currently,the majority of commercial microtools are scaled-down versions of conventional macrotool designs.This approach does not impart optimal performance due to size effects and associated phenomena.Consequently,in-depth analysis and implementation of microcutting mechanics and fundamentals are required to enable successful industrial adaptation in microtool design and fabrication methods.This paper serves as a review of recent microtool designs,materials,and fabrication methods.Analysis of tool performance is discussed,and new approaches and techniques are examined.Of particular focus is tool wear suppression in the machining of hard materials and associated process parameters,including internal cooling and surface patterning techniques.The review concludes with suggestions for an integrated design and fabrication process chain which can aid industrial microtool manufacture.
文摘Infection Prevention and Control is a Quality Standard and is crucial in all health care facilities. Many hospitals remain deficient in trained infection control professionals (ICPs), and now there is an acute awareness of the need to correct this shortfall. The objectives of the study were to describe the current status of ICP programs at ministry of health (MOH) and to evaluate the current status of infection prevention and control programs at health care facilities in kingdom of Saudi Arabia. A cross sectional interview and a self assessment study were conducted on infection prevention and control (IPC) program in Saudi Arabia. All the MOH hospital in all regions was randomly chosen to the study setting. The selection of facilities was done at random with a clear intention to include twenty regions. A random sample was taken from these hospitals with sample size 56 (55.4%), by Multi stage random sampling technique. Results showed that the total facility in all over the kingdom was 51.4% where central area covered the facility score 58.2%, followed by western area (54.8%), south (53.7%), east (46.3%), and lastly with (45.8%) north area. Survey revealed that the infrastructure for infection control program in Saudi Arabian hospitals remained underdeveloped. There were defects in the identified components of effective infection control programs.
基金supported in part by the National Natural Science Foundation of China(71361014,61973242,61573265,51665018)the Major Fundamental Research Program of the Natural Science Foundation of Shaanxi Province(2017ZDJC-34)。
文摘Accompanying the unceasing progress of integrated circuit manufacturing technology, the mainstream production mode of current semiconductor wafer fabrication is featured with multi-variety, small batch, and individual customization, which poses a huge challenge to the scheduling of cluster tools with single-wafer-type fabrication. Concurrent processing multiple wafer types in cluster tools, as a novel production pattern, has drawn increasing attention from industry to academia, whereas the corresponding research remains insufficient. This paper investigates the scheduling problems of dual-arm cluster tools with multiple wafer types and residency time constraints. To pursue an easy-to-implement cyclic operation under diverse flow patterns,we develop a novel robot activity strategy called multiplex swap sequence. In the light of the virtual module technology, the workloads that stem from bottleneck process steps and asymmetrical process configuration are balanced satisfactorily. Moreover, several sufficient and necessary conditions with closed-form expressions are obtained for checking the system's schedulability. Finally, efficient algorithms with polynomial complexity are developed to find the periodic scheduling, and its practicability and availability are demonstrated by the offered illustrative examples.
文摘Fuel cycle related activities were accomplished in IPEN-CNEN/SP in laboratory and pilot plant scale and most facilities were built in the 70-80 years. Nevertheless, radical changes of the Brazilian nuclear policy in the beginning of 90＇s determined the interruption of several fuel cycle activities and facilities shutdown. Some laboratory and pilot plant decommissioning activities have been performed in IPEN in the last years. During the operational activities in the decommissioning of old nuclear fuel cycle facilities, the personnel involved in the task had to face several problems. In old facilities, the need of large components dismantling and material removal use to present some difficulties, such as lack of available and near electricity supply. Besides this, the spread out of the superficial contamination in the form of dust or aerosols and the exposure of workers should be as much as possible avoided. Then, the selection and availability of suitable tools for the task, mainly those employed for cutting and segmentation of different materials is of significant importance. Slight hand tools, mainly those powered by rechargeable batteries, facilitate the work, especially in areas where the access is difficult. Based on the experience in the dismantling of some old nuclear facilities of IPEN-CNEN/SP, some tools that would have facilitated the operations were identified and their availability could have improved the quality and efficiency of different individual tasks. In this paper, different cutting problems and techniques, as well as some available commercial hand tools, are presented as suggestion for future activities.
