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旋风分离器进口涡旋感生速度场的减阻增效作用 被引量:9
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作者 付烜 孙国刚 +1 位作者 刘佳 时铭显 《化工学报》 EI CAS CSCD 北大核心 2011年第7期1927-1932,共6页
旋风分离器进口段管路的结构关系着进口气速的分配,直接影响到下游分离空间三维速度场的形式,合理设计进口管的样式是挖掘分离器分离潜力的可能入手之处。采用实验及数值模拟手段,对环管和直管2种进口管路下轴对称双进口分离器的性能与... 旋风分离器进口段管路的结构关系着进口气速的分配,直接影响到下游分离空间三维速度场的形式,合理设计进口管的样式是挖掘分离器分离潜力的可能入手之处。采用实验及数值模拟手段,对环管和直管2种进口管路下轴对称双进口分离器的性能与流场作了对比研究。结果表明,环管进口的分离器分离总效率比两侧进口的平均高1.5个百分点,而压降损失降低25%以上。前者阻力小的原因在于进口环管内气流为局部的涡旋,与分离器内旋涡流动的形式接近,两股气流交汇时碰撞程度轻,附加的额外能耗较小;而总效率提高的原因为,环管进口的分离器切向速度比两侧进口的分离器约高0.15倍进口气速,能增强颗粒受到的离心作用、减小切割粒径,从而提升分离器总效率。根据涡旋理论,局部区域的涡旋会对整个流动空间产生感生的速度场,由于环管进口的分离器进口管内局部涡旋的存在,整个分离空间的切向速度场被增强。这种由涡旋感生速度场提升分离器切向速度的方式,加深了分离器运行过程中压头向速度转换的程度,不会消耗额外的能量。因此,采用旋涡流的进气方式,并合理提高进口涡旋的强度,是分离器分离性能进一步提升的新途径。 展开更多
关键词 旋风分离器 进口管结构 感生速度 减阻 增效
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Use of Accelerators for Biomechanical Analysis of Walking Motion Aided by Wheeled Walking Frames
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作者 Satoru Okamoto 《Journal of Mechanics Engineering and Automation》 2014年第9期699-708,共10页
Walkers improve self-reliability. We examined the effectiveness of a newly developed wheeled walking frame for use by physically handicapped persons. Unstable gaits in walker users were analyzed by tri-axial accelerom... Walkers improve self-reliability. We examined the effectiveness of a newly developed wheeled walking frame for use by physically handicapped persons. Unstable gaits in walker users were analyzed by tri-axial accelerometers and a motion capture system. Several markers were placed on subjects' backs and legs. Subjects were requested to walk around a test course at a comfortable speed, while their motion was recorded by two high-speed video cameras. The activities performed on the test course comprised standing, normal walking, fast walking, and walking over a barrier. Any accidental falls were also recorded. We established the characteristic rules of gait motion using a walker. Furthermore, we demonstrated that gait characteristics are more conveniently extracted from acceleration sensors than from motion capture systems, since the sensors can be affixed to subjects for self-monitoring and goal achievements. The methods employing acceleration sensors are considered suitable for determining the average gait motions of elderly persons living in nursing homes, and can be used to evaluate walking motion before and aider rehabilitation. 展开更多
关键词 Wheeled walking frame gait motion biomechanical analysis acceleration sensor high-speed video camera.
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Comparative Study of the Static Magnetic Field Effects on Growth Rate with Relative Antibiotic Susceptibility in Escherichia coli
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作者 Fouad Houssein Kamel Ashti M. Amin Khonaw Kader Salih Saleem S.Qader 《Journal of Life Sciences》 2013年第7期690-694,共5页
We studied the biological effects of different magnetic fields. Identified bacterial strain Escherichia coli (type I) has been exposed to the dipolar magnetic field force (400, 800, 1200 and 1600 Gausses) which pr... We studied the biological effects of different magnetic fields. Identified bacterial strain Escherichia coli (type I) has been exposed to the dipolar magnetic field force (400, 800, 1200 and 1600 Gausses) which prepared locally with incubation for different period times (24, 48 and 72 hrs) at 37℃. The effects were evaluated by optical density (OD) at 600 nm determining their growth density incorporation with negative control and depending of McFarland turbidity standard (0.5), in addition to its susceptibility to various antibiotics. Results illustrate different forces of magnetic field decreased the growth rate of E. coli in particular at 24 hrs incubation comparing with unexposed or control samples. The magnetic field increased the logarithmic phase within 4-6 hrs of treatment but decreased after 16 to 18 hrs. Furthermore, changes in the antibiotic sensitivity were observed after exposure period of 6 hrs since E. coli cells became more sensitive to certain antibiotics. While after a 16 hrs exposure period, it became more resistant to the same antibiotics comparing with control groups. 展开更多
关键词 Magnetic field BACTERIA optical density Escherichia coli antibiotic susceptibility.
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