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Search Results: 1 - 9 of 9 matches for " cavitations "
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Impact of Standardized Scheme on the Detection of Chest X-Ray Abnormalities and Radiographic Diagnosis of Pulmonary Tuberculosis in Adult  [PDF]
Marie Laure Gharingam, Boniface Moifo, Eric Walter Pefura Yone, André Pascal Kengne, Jean Roger Moulion Tapouh, Annick Laure Edzimbi, Georges Nguefack-Tsague, Samuel Nko’o Amvene
Open Journal of Medical Imaging (OJMI) , 2014, DOI: 10.4236/ojmi.2014.41004
Abstract: Purpose: The complexity of chest radiography (CXR) is a source of variability in its interpretation. We assessed the effect of an interpretation grid on the detection of CXR anomalies and radio- graphic diagnosis of tuberculosis in an endemic area for tuberculosis. Methods: The study was conducted in Yaounde (Cameroon). Six observers (2 pulmonologists, 2 radiologists and 2 senior residents in medical imaging) interpreted 47 frontal CXR twice two months apart without (R1) and with (R2) the aid of an interpretation grid. We focused on the detection of micro nodules (n = 16), cavitations (n = 12), pleural effusion (n = 6), adenomegaly (n = 6), and diagnosis of tuberculosis (n = 23) and cancer (n = 7). Results: The average score for accurate detection of elementary lesions was 40.4% [95%CI: 25% - 58.3%] in R1 and 52.1% [36.9% - 65.3%] in R2. The highest im- provement was observed for micro nodules (19.8%). Cavitations had the highest proportions of accurate detections (58.3% in R1 and 65.3% in R2). The average score of accurate diagnosis was 46.1% in R1 and 57.4% in R2. Accurate diagnosis improved by 3.6% for tuberculosis and 19% for cancer between R1 and R2. Intra-observer agreement was higher for the diagnosis of cancers (0.22 ≤ k ≤ 1) than for diagnosing tuberculosis (0.21 ≤ k ≤ 0.68). Inter-observer agreement was highly variable with a modest improvement for the diagnosis of tuberculosis in R2. Conclusion
液压减振器液压模型与气穴异响研究
罗天洪,金锐超,江礁,胡启国,朱孙科
重庆交通大学学报(自然科学版) , 2014, DOI: 10.3969/j.issn.1674-0696.2014.01.34
Abstract: :?为了降低液压减振器气穴异响,分析了压缩和复原过程中液压油的运动状态和气穴的生成过程,建立了气穴系数与节流孔直径之间的关系模型,以及双筒液压减振器的参数模型;通过Simulink对液压减振器压缩和复原过程的仿真分析,确定了减振器气穴异响与节流孔直径和油液运动黏度的关系。结果表明:减振器的异响可以通过增加节流阀的有效节流直径和降低油液运动黏度来减轻。
RESEARCH OF THE CHARACTERISTICS OF ELECTRIC PULSE DISCHARGE IN CHLORIDE SODIUM SOLUTIONS Исследование характеристик электроимпульсного разряда в водных растворах хлористого натрия
Nagdalyan A. A.,Oboturova N. P.,Barybina L. I.,Lukyanchenko P. P.
Polythematic Online Scientific Journal of Kuban State Agrarian University , 2013,
Abstract: Electro physical and energetic properties of electric pulse discharge in various concentration solutions of chloride sodium as the results of the researches are provided in this article. The possibility of applying the Yutkin effect in technological processes of food industry has been reviewed
Effective Parameters of Ultrasonic Cleaning Process in Metal Cleaning of Al23 and St37 for Process Optimization
T. Mohammadi,M. Gorji,V. Mohammadi
Iranica Journal of Energy and Environment (IJEE) , 2010,
Abstract: Radiation of supersonic waves in static fluid is one of the most advanced methods of industrial washing technique. By radiation of these waves in homogenous environment Washing and cleaning of the polluted industrial machinery parts conducted without any destructive effects. In the present paper, such washing technique on metals such as St37 and Al23 were evaluated. The impacts of effective parameters on metal surfaces and with the purpose of determining the effective cleaning for the removal of pollutants from the metal surfaces were considered. Experiments were conducted with cavitation effects and without utilization of washing substances in the washing process. The results showed that application of supersonic washing technique and the experimental parameters with the aim of minimizing washing time and the optimum fluid temperature in the optimized sonic intensity was accomplished. Supersonic washing may have many advantages such as desired washing quality, balanced energy consumption and protected environment.
HHT Fuzzy Wavelet Neural Network to Identify Incipient Cavitations in Cooling pump of Engine
Li-hong Li,Xiangyang Xu,Yanfang Liu,Qianjin Guo
Journal of Computers , 2011, DOI: 10.4304/jcp.6.3.506-513
Abstract: Incipient cavitations identification is very practical and academic significance for cavity research in cooling pump of engine but it is very complicated. In this paper, a Hilbert-Huang transform(HHT) fuzzy wavelet neural network (FWNN) is proposed for incipient cavitations identification. The main incipient cavitations feature was extracted from entrance pressure fluctuation by the HHT. This FWNN uses wavelet basis function as membership function which shape can be adjusted on line so that the networks have better learning and adaptive ability and at the same time combine the wavelet neural network with fuzzy logical theory to deal with complicated nonlinear, uncertain and fuzzy problem. At last the experiment showed that this identification model can provide fast and reliable incipient cavitations
Experimental Study on Cavitations Erosion
冲蚀与气蚀复合磨损试验研究

LI Jian,ZHANG Yong-zhen,PENG En-gao,QING Xiang-pei,DU San-ming,
李健
,张永振,彭恩高,秦襄培,杜三明

摩擦学学报 , 2006,
Abstract: In three-phase flow, wear of Cavitations and Erosion significantly influences the behaviors of hydraulic turbine. Experimental simulation of three-phase flow wear is very difficult, but it is essential for the research on the wear of hydraulic turbine operating under severely muddy water circumstances in China. Hence, a tester was built for investigating the wear behaviors of cavitations erosion mode of steel specimens under the mixed flow of water, sand and air using an MCF-30 impact erosion-corrosion apparatus. SEM observation on the surface of test-pieces clearly showed wear trace due to cavitations erosion. Subsequent computer simulation of the conditions for cavitations and erosion under water, sand and air three-phase flow was performed so as to understand further mechanisms of cavitations erosion wear. Study indicates that a relatively more realistic simulation of cavitations and erosion requires feasible design of a tester considering some major attributions such as air as the medium in the flow, possible implosion of air bubble under high pressure, and so on. Experimental method and computer simulation of three-phase flow in this study have provided a fundamental for future research in cavitations and erosion.
高速列车铝型材模态参数识别及阻尼影响分析
Modal Parameter Identification of Aluminum Corrugated Section and Damping Effect Analysis

刘佳,王瑞乾,肖新标,金学松,张玉梅,韩健
- , 2016,
Abstract: 为准确辨识像波纹状铝型材板这样的“空腔铝型板”结构模态,利用力锤敲击方法,获取激励点与响应点之间的频率响应函数并进行模态参数识别。模态参数识别过程中,首先获取了复模态指示函数法、稳态图法两种方法的识别结果,结合声振试验探讨识别结果中声腔模态对结构模态的影响,利用模态判定准则(MAC)验证模态重根;进而根据仿真频率和振型,对比两种模态参数识别结果的准确性;最后,基于仿真验证后的模态参数识别方法,探究阻尼材料对于铝型材模态密度和模态阻尼比的影响。结论表明:对波纹状铝型材板而言,复模态指示函数法结合声振试验分析可获取其真实模态;喷涂4 mm123WF阻尼材料后,模态阻尼比在整个频段内大大提高,模态密度在500 Hz、1 250 Hz和1 600 Hz频段内显著降低;结合我国高速列车车体板件振动实测频谱,建议车体顶板、边顶板、侧墙中部和侧板使用4 mm此类型阻尼材料。
For the accurate identification of the physical modes of the aluminum corrugated-section plate with cavities, the hammer excitation method is hired to obtain the frequency response functions of the plate and its modal parameters are identified. In the modal parameter identification, the results obtained by using two methods are compared, and the two methods are, respectively, called the complex mode indicator function and the stabilization diagram. The influence of acoustic modes on the vibration modes is analyzed through the acoustic-vibration test, and the multiple roots are validated by using the modal assurance criterion (MAC). The accuracy of the two methods is validated through comparing the simulation results. The influence of damping materials by means of identification of modal parameters after the multiple roots validated is further analyzed. The obtained conclusions are as follows:as for the plate of aluminum corrugated section, the physical modes can be recognized with the complex mode indicator function with the aid of acoustic-vibration test; using the damping material can improve the modal damping significantly and dramatically reduce modal density at 500 Hz, 1250 Hz and 1600 Hz. This type of damping material is suitable for use of high speed train car roof, roof, side wall and side panels with low vibration and noise, according to the measured frequency spectrum of plate vibration of high-speed trains from the fields
明流泄水道突扩突跌掺气设施空腔长度研究
刘超,李龙国,庄文化,李乃稳,刘慧芬
- , 2015, DOI: 10.15961/j.jsuese.2015.03.001
Abstract: 中文摘要: 为了查明短有压进口泄洪洞下游明流泄水道上突扩突跌掺气设施底、侧空腔长度随掺气坎尺寸和水流弗劳德数的变化规律,采用模型试验,测试了不同掺气坎尺寸在不同水流条件下的底、侧空腔长度,分析了量纲底、侧空腔长度与掺气坎尺寸和水流弗劳德数的相互关系。结果表明:底空腔长度随着挑坎高度的增加、挑坎坡度的增大、侧扩宽度的增加和水流弗劳德数的增大而增大;侧空腔长度与挑坎高度、挑坎坡度关系不大,随着侧扩宽度的增加而增大,随水流弗劳德数的变化规律为:当侧扩宽度较大时,侧空腔长度随水流弗劳德数的增大而线性增大;当侧扩宽度较小时,侧空腔长度随水流弗劳德数的增大而略微减小。
Abstract:For an aerator with sudden lateral enlargement and vertical drop in free flow chute,the cavity length is governed by a number of independent parameters, including the Froude number,the ramp height of vertical drop, the ramp angle of vertical drop,and the lateral enlargement width of sidewalls,etc.Based on model experiments,the effects of above-mentioned parameters were observed on the bottom cavity length and the lateral cavity length.The results showed that the bottom cavity length is closely related to the ramp height,the ramp angle,the lateral enlargement width and the Froude number,and with higher ramp height,bigger ramp angle,wider lateral enlargement width,and higher Froude number,the bottom cavity length is longer.Yet the lateral cavity length is mainly connected with the lateral enlargement width and the Froude number,which has little relation to the ramp height and the ramp angle.For the lateral cavity length,it increases with the lateral enlargement width.At the condition of larger size of lateral enlargement,the lateral cavity length increases linearly with the Froude number,while a little decreases when the size of lateral enlargement is smaller.
突扩突跌掺气坎底空腔长度计算
刘超,李龙国,李乃稳,庄文化,刘慧芬
- , 2015, DOI: 10.15961/j.jsuese.2015.04.001
Abstract: 中文摘要: 突扩突跌掺气坎的底空腔长度既与水力条件和底部掺气坎结构参数有关,也与侧墙掺气坎结构参数有关。以往的底空腔长度计算方法,均针对仅采用底部掺气坎,未设置侧墙掺气坎这类掺气设施,不能反映出侧墙掺气坎结构参数对底空腔长度的影响。基于射流微元体受力平衡法,提出了一种求解明流泄水道突扩突跌掺气坎底空腔长度的计算方法,该方法能够全面反映突扩突跌掺气坎底空腔长度受底部掺气坎、侧墙掺气坎结构参数和水力学参数的影响。通过与30组试验资料和已有研究成果的对比,表明所提出的计算方法具有较高的精度
Abstract:For an aerator with sudden lateral enlargement and vertical drop in free flow chute,the bottom cavity length is governed not only by hydraulic parameters,but also by structural parameters of the bottom aerator and lateral aerator.The previous calculation method for the bottom cavity length failed to consider the effect of lateral aerator’s structural parameters.Based on the hydrodynamic analysis of micro water unit of jet flow from aerator,a new calculation method for the bottom cavity length of jet flow from chute aerators with sudden lateral enlargement and vertical drop was obtained,which considers overall effects of the above mentioned parameters.The comparison with 30 groups of experimental data and existing research results showed that the calculating method proposed in this paper has higher accuracy.
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