This paper analyzes current spectrum utilization from all aspects based on related methods of spectrum measurement. The measurement results show that some spectrum resources are not used effectively due to current fix...This paper analyzes current spectrum utilization from all aspects based on related methods of spectrum measurement. The measurement results show that some spectrum resources are not used effectively due to current fixed spectrum allocation policy, and the spectrum occupancy varies dramatically in terms of time and space. These results provide basis for the development of next generation wireless communication technologies such as Cognitive Radio (CR).展开更多
For the best dynamic performance of a co-cured composite damping instrument panel with light weight and high strength,a multilayer sandwich structure with polymethacrylimide( PMI) foam combined with embedded and co-cu...For the best dynamic performance of a co-cured composite damping instrument panel with light weight and high strength,a multilayer sandwich structure with polymethacrylimide( PMI) foam combined with embedded and co-cured composite damping structure is proposed. The structue can maintain the excellent mechanical properties of composite materials,and achieve the damping and light effect at the same time. Input variables which may affect the dynamic performance of the instrument panel were selected and variance based importance measure was analyzed through multifinite element method( FEM) analysis. Using the results of the importance measure analysis,with other design requirements,the important design variable was optimized and an instrument panel with the best dynamic performance under the requirements of light weight and high strength was obtained. The structure of the instrument panel can provide reference for the design of precision,high speed,and dynamic composite component. The importance measure analysis of dynamic performance of the instrument panel can provide a reference for relative design.展开更多
Objective To explore the differences between anatomic and CT measurements for anterior transoral axial pedicle screw placement. Methods C2 vertebrae of 60 adult spines were measured anatomically,while 20 adult spine v...Objective To explore the differences between anatomic and CT measurements for anterior transoral axial pedicle screw placement. Methods C2 vertebrae of 60 adult spines were measured anatomically,while 20 adult spine vertebrae were展开更多
Based on measuring the cross-spectrum density of sound pressure between two hydrophones, the facility for underwater sound intensity measurement is investigated and designed. According to the principle of two-hydropho...Based on measuring the cross-spectrum density of sound pressure between two hydrophones, the facility for underwater sound intensity measurement is investigated and designed. According to the principle of two-hydrophone method for intensity measurement, the error analysis is carried out. Given the method of sound intensity measurement calibration for this underwater sound intensity measurement facility, the uncertainty of intensity measurement by this facility is evaluated. It is shown that the analysis and evaluation are agreeable to the experimental results.展开更多
Before mass production of individual components industries may assess its capability to produce it according to specifications.This capability assessment is a common requirement in the automotive sector.This work show...Before mass production of individual components industries may assess its capability to produce it according to specifications.This capability assessment is a common requirement in the automotive sector.This work shows a case study,providing an in-depth analysis,on a critical component and finds evidence of process degradation over two years of production,quantified through capability analysis.At pre-production,it was concluded that the process was capable and,thus,no statistical process control was done during its production.Over the months no defective units were detected but then its level began to increase and it was apparent that process variability had increased and the process was no longer capable.Process improvement activities were developed using known quality tools and methodologies.This work shows how the control plan initially defined became obsolete and discusses the need to periodically review quality control mechanisms.展开更多
文摘This paper analyzes current spectrum utilization from all aspects based on related methods of spectrum measurement. The measurement results show that some spectrum resources are not used effectively due to current fixed spectrum allocation policy, and the spectrum occupancy varies dramatically in terms of time and space. These results provide basis for the development of next generation wireless communication technologies such as Cognitive Radio (CR).
文摘For the best dynamic performance of a co-cured composite damping instrument panel with light weight and high strength,a multilayer sandwich structure with polymethacrylimide( PMI) foam combined with embedded and co-cured composite damping structure is proposed. The structue can maintain the excellent mechanical properties of composite materials,and achieve the damping and light effect at the same time. Input variables which may affect the dynamic performance of the instrument panel were selected and variance based importance measure was analyzed through multifinite element method( FEM) analysis. Using the results of the importance measure analysis,with other design requirements,the important design variable was optimized and an instrument panel with the best dynamic performance under the requirements of light weight and high strength was obtained. The structure of the instrument panel can provide reference for the design of precision,high speed,and dynamic composite component. The importance measure analysis of dynamic performance of the instrument panel can provide a reference for relative design.
文摘Objective To explore the differences between anatomic and CT measurements for anterior transoral axial pedicle screw placement. Methods C2 vertebrae of 60 adult spines were measured anatomically,while 20 adult spine vertebrae were
文摘Based on measuring the cross-spectrum density of sound pressure between two hydrophones, the facility for underwater sound intensity measurement is investigated and designed. According to the principle of two-hydrophone method for intensity measurement, the error analysis is carried out. Given the method of sound intensity measurement calibration for this underwater sound intensity measurement facility, the uncertainty of intensity measurement by this facility is evaluated. It is shown that the analysis and evaluation are agreeable to the experimental results.
基金This work has been supported by COMPETE:POCI-01-0145-FEDER-007043FCT–Fundação para a Ciência e Tecnologia within the Project Scope:UID/CEC/00319/2013.
文摘Before mass production of individual components industries may assess its capability to produce it according to specifications.This capability assessment is a common requirement in the automotive sector.This work shows a case study,providing an in-depth analysis,on a critical component and finds evidence of process degradation over two years of production,quantified through capability analysis.At pre-production,it was concluded that the process was capable and,thus,no statistical process control was done during its production.Over the months no defective units were detected but then its level began to increase and it was apparent that process variability had increased and the process was no longer capable.Process improvement activities were developed using known quality tools and methodologies.This work shows how the control plan initially defined became obsolete and discusses the need to periodically review quality control mechanisms.