期刊文献+
共找到4,062篇文章
< 1 2 204 >
每页显示 20 50 100
Non-Contact System for Global Reporting Format (GRF) Automation: Contaminant Body Detection and Depth Estimation in the Case of Rainy Weather
1
作者 Dieudonné Sama Doua Allain Gnabahou +1 位作者 Brahima Bayili Oula Fayçal Denilson Ouattara 《Open Journal of Applied Sciences》 2023年第11期2127-2140,共14页
The paper designed a non-contact system in order to perform the application (on a runway) of the Global Reporting Format (GRF) developed by International Civil Aviation Organization (ICAO). The system involves devices... The paper designed a non-contact system in order to perform the application (on a runway) of the Global Reporting Format (GRF) developed by International Civil Aviation Organization (ICAO). The system involves devices that film the surface (a runway in our case) from the air and displays the contaminant (water) body and measures the depth of the water automatically during the inspection. While measuring, data are sent to a computer used as a receiver. The developed devices are automatic devices implemented specially to use during rainy weather or even for some other cases. The aerial system uses a raspberry pi 4 model B, a camera, a laser sensor, an ultrasonic module, a Virtual Network Computing (VNC) and python codes developed by the authors. Results obtained show that using these devices to retrieve the Runway Condition Report (RCR) is very fast and human presence on the runway is not needed. The results obtained using these devices show that the method used herein is a proper solution to the GRF issues in the rainy areas, where the contaminant body detection and the accurate depth measurement were not well estimated because of the lack of a suitable method. 展开更多
关键词 Global Reporting Format Runway Surface Condition Runway Contaminant non-contact System ICAO
下载PDF
NON-CONTACT MEASUREMENT SYSTEM OF FREEFORM SURFACE AND NURBS RECONSTRUCTION OF MEASUREMENT POINTS 被引量:4
2
作者 Li Jian Wang Wen Chen Zichen Institute of Advanced Manufacturing Engineering, Zhejiang University, Hangzhou 310027, China 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2002年第4期366-371,共6页
Based on the development of the non-contact measurement system of free-formsurface, NURBS reconstruction of measurement points of freeform surface is effectively realized bymodifying the objective function and recursi... Based on the development of the non-contact measurement system of free-formsurface, NURBS reconstruction of measurement points of freeform surface is effectively realized bymodifying the objective function and recursive procedure and calculating the optimum number ofcontrol points. The reconstruction precision is evaluated through Ja-cobi's transformation method.The feasibility of the measurement system and effectiveness of the reconstruction algorithm aboveare proved by experiment. 展开更多
关键词 freeform surface non-contact measurement NURBS precision evaluation
下载PDF
Design of Non-contact On-load Automatic Regulating Voltage Transformer 被引量:5
3
作者 Zhao Qi 《Journal of Northeast Agricultural University(English Edition)》 CAS 2015年第3期91-96,共6页
At present, an automatic-mechanic contact tap-changer is widely used in power system, but it can not frequently operate. In addition, arc will occur when the switch changes. In order to solve these two problems, this ... At present, an automatic-mechanic contact tap-changer is widely used in power system, but it can not frequently operate. In addition, arc will occur when the switch changes. In order to solve these two problems, this paper presented an automatic on-load voltage-regulating distributing transformer which employed non-contact solid-state relay as tap-changer, and mainly introduced its structure, basic principal, design method of each key link and experimental results. Laboratory simulation experiments informed that the scheme was feasible. It was a smooth and effective experiment device, which was practical in application. 展开更多
关键词 solid-state relay on-load tap-changer non-contact distributing transformer design
下载PDF
Non-contact tensile viscoelastic characterization of microscale biological materials 被引量:3
4
作者 Yuhui Li Yuan Hong +7 位作者 Guang-Kui Xu Shaobao Liu Qiang Shi Deding Tang Hui Yang Guy M.Genin Tian Jian Lu Feng Xu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2018年第3期589-599,共11页
Many structures and materials in nature and physiology have important "meso-scale" structures at the micron lengthscale whose tensile responses have proven difficult to characterize mechanically. Although techniques... Many structures and materials in nature and physiology have important "meso-scale" structures at the micron lengthscale whose tensile responses have proven difficult to characterize mechanically. Although techniques such as atomic force microscopy and micro- and nano-identation are mature for compression and indentation testing at the nano-scale, and standard uniaxial and shear rheometry techniques exist for the macroscale, few techniques are applicable for tensile-testing at the micrometre-scale, leaving a gap in our understanding of hierarchical biomaterials. Here, we present a novel magnetic mechanical testing (MMT) system that enables viscoelastic tensile testing at this critical length scale. The MMT system applies non-contact loading, avoiding gripping and surface interaction effects. We demonstrate application of the MMT system to the first analyses of the pure tensile responses of several native and engineered tissue systems at the mesoscale, showing the broad potential of the system for exploring micro- and meso-scale analysis of structured and hierarchical biological systems. 展开更多
关键词 Mechanical testing Hierarchical biomaterials non-contact actuation Microscale analysis
下载PDF
An approach to a non-contact vital sign monitoring using dual-frequency microwave radars for elderly care 被引量:3
5
作者 Satoshi Suzuki Takemi Matsui +2 位作者 Masayuki Kagawa Takafumi Asao Kentaro Kotani 《Journal of Biomedical Science and Engineering》 2013年第7期704-711,共8页
This study aimed to produce a prototype system for non-contact vital sign monitoring of the elderly using microwave radar with the intention of reducing the burdens on monitored individuals and nursing caregivers. In ... This study aimed to produce a prototype system for non-contact vital sign monitoring of the elderly using microwave radar with the intention of reducing the burdens on monitored individuals and nursing caregivers. In addition, we tested the ability of the proposed prototype system to measure the respiratory and heart rates of the elderly in a nursing home and discussed the systems effectiveness and problems by examining results of real-time monitoring. The prototype system consisted of two 24-GHz microwave radar antennas and an analysis system. The antennas were positioned below a mattress to monitor motion on the body surface for measuring cardiac and respiratory rates from the dorsal side of the subjects (23.3 ± 1.2 years) who would be lying on the mattress. The heart rates determined by the prototype system correlated significantly with those measured by electrocardiography (r = 0.92). Similarly, the respiratory rates determined by the prototype correlated with those obtained from respiration curves (r = 0.94). Next, we investigated the effectiveness of the prototype system with 7 elderly patients (93.3 ± 10.56 years) at a nursing home. The proposed system appears to be a promising tool for monitoring the vital signs of the elderly in a way that alleviates the need to attach electrodes overnight to confirm patient safety. 展开更多
关键词 non-contact Sensing VITAL SIGNS Microwave Radar ELDERLY CARE
下载PDF
A METHOD FOR THE ANALYSIS OF DYNAMIC RESPONSE OF STRUCTURE CONTAINING NON-SMOOTH CONTACTABLE INTERFACES 被引量:3
6
作者 刘晶波 刘书 杜修力 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 1999年第1期63-72,共10页
A novel single-step method is proposed for the analysis of dynamic response of visco-elastic structures containing non-smooth contactable interfaces. In the method, a two-level algorithm is employed for dealing with a... A novel single-step method is proposed for the analysis of dynamic response of visco-elastic structures containing non-smooth contactable interfaces. In the method, a two-level algorithm is employed for dealing with a nonlinear boundary condition caused by the dynamic contact of interfaces. At the first level, an explicit method is adopted to calculate nodal displacements of global viscoelastic system without considering the effect of dynamic contact of interfaces and at the second level, by introducing contact conditions of interfaces, a group of equations of lower order is derived to calculate dynamic contact normal and shear forces on the interfaces. The method is convenient and efficient for the analysis of problems of dynamic contact. The accuracy of the method is of the second order and the numerical stability condition is wider than that of other explicit methods. 展开更多
关键词 non-smooth contactable interfaces visco-elastic structure dynamic response
下载PDF
Non-contact evaluation of the resonant frequency of a microstructure using ultrasonic wave 被引量:1
7
作者 X. Kang X. Y. He +1 位作者 C.J. Tay C. Quan 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2010年第2期317-323,共7页
This paper presents a novel non-contact method for evaluating the resonant frequency of a microstructure, Firstly, the microstructure under test is excited by ultrasonic waves. This excitation method does not impose a... This paper presents a novel non-contact method for evaluating the resonant frequency of a microstructure, Firstly, the microstructure under test is excited by ultrasonic waves. This excitation method does not impose any undefined load on the specimen like the electrostatic excitation and also this is the first actual use of ultrasonic wave for exciting a microstructure in the literature. Secondly, the amplitudes of the microstructure are determined by image edge detection using a Mexican hat wavelet transform on the vibrating images of the microstructure. The vibrating images are captured by a CCD camera when the microstructure is vibrated by ultrasonic waves at a series of discrete high frequencies (〉30 kHz). Upon processing the vibrating images, the amplitudes at various excitation frequencies are obtained and an amplitude-frequency spectrum is obtained from which the resonant frequency is subsequently evaluated. A micro silicon structure consisting of a perforated plate (192 × 192 μm) and two cantilever beams (76 × 43 μm) which is about 4 μm thickness is tested. Since laser interferometry is not required, thermal effects on a test object can be avoided. Hence, the setup is relatively simple. Results show that the proposed method is a simple and effective approach for evaluating the dynamic characteristics of microstructures. 展开更多
关键词 non-contact Microstructure· Resonant frequency Ultrasonic wave Image processing
下载PDF
Non-Contact Method of Heart Rate Measurement Based on Facial Tracking 被引量:2
8
作者 Ruqiang Huang Weihua Su +1 位作者 Shiyue Zhang Wei Qin 《Journal of Computer and Communications》 2019年第5期17-28,共12页
Image photoplethysmography can realize low-cost and easy-to-operate non-contact heart rate detection from the facial video, and effectively overcome the limitations of traditional contact method in daily vital sign mo... Image photoplethysmography can realize low-cost and easy-to-operate non-contact heart rate detection from the facial video, and effectively overcome the limitations of traditional contact method in daily vital sign monitoring. However, it is hard to obtain more accurate heart rate detection values under the conditions of subject’s facial movement, weak ambient light intensity and long detection distance, etc. In this article, a non-contact heart rate detection method based on face tracking is proposed, which can effectively improve the accuracy of non-contact heart rate detection method in practical application. The corner tracker algorithm is used to track the human face to reduce the motion artifact caused by the movement of the subject’s face and enhance the use value of the signal. And the maximum ratio combining algorithm is used to weight the pixel space pulse wave signal in the facial region of interest to improve the pulse wave extraction accuracy. We analyzed the facial images collected under different experimental distances and action states. This proposed method significantly reduces the error rate compared with the independent component analysis method. After theoretical analysis and experimental verification, this method effectively reduces the error rate under different experimental variables and has good consistency with the heart rate value collected by the medical physiological vest. This method will help to improve the accuracy of non-contact heart rate detection in complex environments. 展开更多
关键词 HEART Rate non-contacting MAXIMUM RATIO COMBINING FACIAL Video
下载PDF
Numerical simulation of non-contact explosion by door breaching explosive 被引量:1
9
作者 蒋飞 韩峰 王建中 《Journal of Beijing Institute of Technology》 EI CAS 2013年第1期1-5,共5页
Aiming at the estimation of personal injury attached by counter-terrorist door breaching explosive blast wave, according to the actual scene, four typical application space models of count- er-terrorist door breaching... Aiming at the estimation of personal injury attached by counter-terrorist door breaching explosive blast wave, according to the actual scene, four typical application space models of count- er-terrorist door breaching explosives are established, and numerical simulation of air-blast wave propagation by non-contact explosion counter-terrorist door breaching explosive are achieved. The research results show that the overpressure behind the target door is attenuated deeply through the burglary resistant safety door, and the propagation of blast wave and the damage effect under differ- ent space conditions are obviously different. 展开更多
关键词 non-contact explosion blast wave numerical simulation
下载PDF
Non-contact monitoring and analysis system for tunnel surrounding rock deformation of underground engineering 被引量:1
10
作者 YANG Song-lin, WANG Bin, JI Sheng-yue, LIU Wei-ning, SHI Hong-yun (Beijing Jiaotong University, Beijing 100044, China) 《中国有色金属学会会刊:英文版》 CSCD 2005年第S1期96-99,共4页
It is very important to monitor surrounding rock deformation in tunnel construction. The principle, function, development and application of the system composed of a total station and computer for monitoring and analy... It is very important to monitor surrounding rock deformation in tunnel construction. The principle, function, development and application of the system composed of a total station and computer for monitoring and analyzing surrounding rock deformation were discussed. The new methods of two free station of 3D measurement and its mathematic adjustment mode were presented. The development of software for total station on-board and post for computer were also described. Without centering it and measuring its height, the total station controlled by the software on-board can fulfill the whole measurements to target points. Monitoring data can be processed by the post software and results of regression analysis, forecasting information of the tunnel surrounding rock deformation can be provided in time. The practical use shows that this system is practicable, highly accurate and efficient. It satisfies the needs of safety and information construction in tunnel construction of underground engineering. 展开更多
关键词 TUNNEL construction deformation of SURROUNDING ROCK TOTAL STATION non-contact monitoring data processing and analysis
下载PDF
Suppression of Vortex Precession in a Non-Contact Handling Device by a Circular Column 被引量:2
11
作者 Shouichiro Iio Katsuya Hayashi +3 位作者 Eri Akahane Yusuke Katayama Xin Li Toshiharu Kagawa 《Journal of Flow Control, Measurement & Visualization》 2016年第2期70-78,共9页
Vortex levitation attains non-contact handling by injecting air through a tangential nozzle into a cylindrical cup generating the swirling flow. The precessing of the swirling flow causes pressure fluctuation. This ph... Vortex levitation attains non-contact handling by injecting air through a tangential nozzle into a cylindrical cup generating the swirling flow. The precessing of the swirling flow causes pressure fluctuation. This phenomenon becomes apparent as the gap between the cup and workpiece increases, which significantly disturbs the stability of conveyance. In this paper, suppression of pressure fluctuation by a cylindrical column that stabilizes the vortex levitation is described and its mechanism is mentioned. According to the experimental set up, the pressure was measured at the center of the workpiece and the wall of the cup;velocity field under the work piece was visualized by PIV. The result suggested that the larger diameter column denoted the effect on suppression of the fluctuation because the precessing of the swirling flow became stable. On the other hand, variation of the column thickness had insignificant effect on suppressing the fluctuation, but sucking force became weakened since the swirling velocity decreased. 展开更多
关键词 non-contact Handling Swirling Flow Pressure Fluctuation VISUALIZATION
下载PDF
Test on an Optimized Cylindrical Non-contact Piezoelectric Actuator
12
作者 Chen Heng Chen Chao +2 位作者 Yang Dong Wang Junshan Ge Yuyu 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2017年第1期43-48,共6页
An optimization design for the cylindrical non-contact piezoelectric actuator is presented after analyzing the acoustic radiation pressure and acoustic viscous force.By adding the specific microstructure on the rotor ... An optimization design for the cylindrical non-contact piezoelectric actuator is presented after analyzing the acoustic radiation pressure and acoustic viscous force.By adding the specific microstructure on the rotor to alter the near-field sound effect and maximize the use of high intensity acoustic field induced by the stator to drive the rotor,the rotor speed is increased.The finite element analysis of the acoustic field induced by a variety of rotors with different structures is conducted,A prototype is manufactured,the speed-test system for the actuator is built,and the driving characteristics are measured.The results suggest that the rotation speed of the rotor can reach 4 167r/min,which demonstrates that the driving characteristics of cylindrical non-contact piezoelectric actuator are successfully improved using the optimization method proposed. 展开更多
关键词 PIEZOELECTRIC ACTUATOR microstructure FINITE ELEMENT analysis non-contact
下载PDF
Non-Contact Electromagnetic Exciter Design with Linear Control Method
13
作者 WANG Lin XIONG Xianzhi XU Hua 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2017年第1期135-143,共9页
A non-contact type force actuator is necessary for studying the dynamic performance of a high-speed spindle system owing to its high-speed operating conditions. A non-contact electromagnetic exciter is designed for id... A non-contact type force actuator is necessary for studying the dynamic performance of a high-speed spindle system owing to its high-speed operating conditions. A non-contact electromagnetic exciter is designed for identifying the dynamic coefficients of journal bearings in high-speed grinding spindles. A linear force control method is developed based on PID controller. The influence of amplitude and frequency of current, misalignment and rotational speed on magnetic field and excitation force is investigated based on two-dimensional finite element analysis. The electromagnetic excitation force is measured with the auxiliary coils and calibrated by load cells. The design is validated by the experimental results. Theoretical and experimental investigations show that the proposed design can accurately generate linear excitation force with sufficiently large amplitude and higher signal to noise ratio. Moreover, the fluctuations in force amplitude are reduced to a greater extent with the designed linear control method even when the air gap changes due to the rotor vibration at high-speed conditions. Besides, it is possible to apply various types of excitations: constant, synchronous, and non-synchronous excitation forces based on the proposed linear control method. This exciter can be used as linear-force exciting and controlling system for dynamic performance study of different high-speed rotor-bearing systems. 展开更多
关键词 non-contact excitation electromagnetic exciter journal bearing finite element analysis
下载PDF
All-optical Quantitative Framework for Bioluminescence Tomography with Non-contact Measurement
14
作者 Xue-Li Chen Heng Zhao +3 位作者 Xiao-Chao Qu Duo-Fang Chen Xiao-Rui Wang Ji-Min Liang 《International Journal of Automation and computing》 EI 2012年第1期72-80,共9页
In this contribution, we present an all-optical quantitative framework for bioluminescence tomography with non-contact measurement. The framework is comprised of four indispensable steps: extraction of the geometrica... In this contribution, we present an all-optical quantitative framework for bioluminescence tomography with non-contact measurement. The framework is comprised of four indispensable steps: extraction of the geometrical structures of the subject, light flux reconstruction on arbitrary surface, calibration and quantification of the surface light flux and internal bioluminescence reconstruction. In particular, the geometrical structures are retrieved using a completely optical method and captured under identical viewing conditions with the bioluminescent images. As a result, the proposed framework avoids the utilization of computed tomography or magnetic resonance imaging to provide the geometrical structures. On the basis of experimental measurements, we evaluate the performance of the proposed all-optical quantitative framework using a mouse shaped phantom. Preliminary result reveals the potential and feasibility of the proposed framework for bioluminescence tomography. 展开更多
关键词 ALL-OPTICAL biol tomography quantitative framework non-contact surface extraction.
下载PDF
A Contact and Non-Contact Hybrid Profilometer with Large Range
15
作者 YUN Jianping YANG Xudong +1 位作者 XIE Tiebang CHANG Suping 《Wuhan University Journal of Natural Sciences》 CAS 2007年第6期1066-1072,共7页
A novel hybrid instrument of contact and non-contact measurement with large range is developed, and both measurement systems are based on a Linnik interference microscope and on white-light interference measuring tech... A novel hybrid instrument of contact and non-contact measurement with large range is developed, and both measurement systems are based on a Linnik interference microscope and on white-light interference measuring techniques. The ambiguity presented in conventional monochromatic interferometers is not present in the contact and non-contact measurement, and they have a virtually unlimited unambiguous range. For the contact measurement, the vertical measuring range is ±5 mm with a resolution of 1 nm and the horizontal measuring range is ±25 mm in x-range and y-range with a resolution of 1.25 μm; for the non-contact measurement, the vertical measuring range is ~5 mm with a resolution of 1 nm and the horizontal resolution better than 0.5 urn. 展开更多
关键词 surface topography contact/non-contact measurement interference microscope
下载PDF
Research on Non-Contact Weak Current Detection Technology
16
作者 Bo Chen Sai Wu +4 位作者 Rui Wang Changlei Liu Jindong Lu Kui Deng Liang Ge 《Journal of Electromagnetic Analysis and Applications》 2018年第4期67-75,共9页
With the continuous development of industrial technology, the weak current plays an increasingly important role in all fields of life. In order to facilitate the user to carry, the study of contactless weak current me... With the continuous development of industrial technology, the weak current plays an increasingly important role in all fields of life. In order to facilitate the user to carry, the study of contactless weak current measurement technology is also emerging. This article’s design idea is based on two-dimensional reluctance sensor device built non-contact weak current detection system. The system uses the reluctance sensor HMC1002 to collect the current signal and the temperature sensor DS18B20 to compensate the temperature. The signals collected by the reluctance sensor and the temperature sensor are extremely weak. After being amplified by the amplifying circuit, the signal is conducive to subsequent detection and processing. Filter circuit can filter out interference signals to achieve the goal of improving accuracy. After the corresponding algorithm of the microcontroller will convert the signal voltage, easy to read and store, thus designing a non-contact current measurement capable of detecting weak currents and achieving higher accuracy. 展开更多
关键词 WEAK CURRENT Reluctance SENSOR non-contact TEMPERATURE Compensate
下载PDF
Non-Contact Blood Pressure Measurement Based on IPPG
17
作者 Jiancheng Zou Shouyu Zhou +1 位作者 Bailin Ge Xin Yang 《Journal of New Media》 2021年第2期41-51,共11页
Blood pressure is an important physiological parameter to reflect human vital signs.In order to achieve the non-contact dynamic blood pressure acquisition based on ordinary optical camera,a theoretical understanding o... Blood pressure is an important physiological parameter to reflect human vital signs.In order to achieve the non-contact dynamic blood pressure acquisition based on ordinary optical camera,a theoretical understanding of the functional relationship between blood pressure and pulse wave signal conduction time.And through imaging photoelectric plethysmography(IPPG),pulse wave signal conduction time of forehead and hand was obtained with ordinary optical camera.First,the pulse wave conduction time was obtained by recording the video with an ordinary optical camera.Second,real-time blood pressure values were collected.Finally,based on the relationship between blood pressure and pulse wave conduction time,a non-contact blood pressure measurement prediction model was obtained through neural network fitting.So that non-contact blood pressure measurement with optical camera could be completed.The method in this paper has several advantages,such as low requirements on measuring equipment,low cost,and simple operation.It can let people get rid of the discomfort caused by measuring equipment such as cuff and can measure blood pressure at any time.The predicted blood pressure results were compared with an Omron wrist electronic sphygmomanometer.The calculated error of systolic blood pressure is-9.28%~3.16%,and the error of diastolic blood pressure is-9.84~4.35%. 展开更多
关键词 non contact blood pressure measurement imaging photoelectric plethysmography(IPPG) pulse wave conduction time
下载PDF
Assessment of Non-Contact Measurement Using a Microwave Sensor to Jugular Venous Pulse Monitoring
18
作者 Satoshi Suzuki Masaaki Hoshiga +1 位作者 Kentaro Kotani Takafumi Asao 《Journal of Biomedical Science and Engineering》 2021年第3期94-102,共9页
The jugular venous pulse (JVP) waveform provides an insight into right heart function, and its assessment is important in patients with heart failure. However, the conventional pulse-transducer (contact) method for mo... The jugular venous pulse (JVP) waveform provides an insight into right heart function, and its assessment is important in patients with heart failure. However, the conventional pulse-transducer (contact) method for monitoring this waveform is not frequently used because it requires a high degree of skill. The aim of this study was to confirm the effectiveness of a prototype non-contact system that employs microwave radar (24 GHz, 7 mW;non-contact system) for JVP measurement. Experiments were conducted on eight healthy male volunteers (21.88 ± 0.99 years). JVP measurements were compared between the conventional contact method and the proposed non-contact method. Change in JVP waveform was measured in response to an angle of reclining in five steps from the supine position to 75<span style="white-space:nowrap;">°</span> of elevation. The obtained JVP measurements were similar between the two methods. Because in the non-contact method the faint pulsation of the JVP is not suppressed by the pressure of a sensor placed on the skin, the prototype microwave radar system is particularly suitable for evaluating the JVP waveform. 展开更多
关键词 Microwave Radar non-contact Monitoring Jugular Venous Pressure Right Heart Function
下载PDF
Non-Contact Velocity Measurement of Japanese Cedar Columns Using Air-Coupled Ultrasonics
19
作者 Masumi Hasegawa Misaki Mori Junji Matsumura 《World Journal of Engineering and Technology》 2016年第1期45-50,共6页
The ultrasonic wave velocities of Japanese cedar columns were measured using a non-contact method. An air-coupled ultrasonic wave was propagated through the axial and lateral directions of wood. The velocities in the ... The ultrasonic wave velocities of Japanese cedar columns were measured using a non-contact method. An air-coupled ultrasonic wave was propagated through the axial and lateral directions of wood. The velocities in the axial direction (V<sub>L</sub>) showed the minimum values around the pith. The averaged V<sub>L</sub> increased from 3600 m/s towards the outside of measurement area and attained the maximum values (=4010 m/s). The velocities in the lateral direction (V<sub>RT </sub>) showed no tendency among measurement points. The averaged V<sub>RT </sub> was 1450 m/s. The velocities obtained using the non-contact method showed a significant positive relationship with those obtained using the contact method. The averaged ratio of V<sub>L</sub> to V<sub>RT </sub> was measured to be approximately 2.2 to 2.8. These ratios were in agreement with those from a contact method. These findings suggest that it is possible to measure the velocity in Japanese cedar columns with the non-contact method by using air-coupled ultrasonics. 展开更多
关键词 Air-Coupled Ultrasonics VELOCITY non-contact Method Nodestructive Evaluation Japanese Cedar
下载PDF
Calculating method of contact stress for non-circular gears
20
作者 李纪强 刘忠明 颜世铛 《Journal of Chongqing University》 CAS 2015年第1期19-24,共6页
According to Hertz theory, the difference of contact stress for non-circular gears and equivalent gears is compared in the paper, a calculating method of contact stress for non-circular gears by using equivalent gears... According to Hertz theory, the difference of contact stress for non-circular gears and equivalent gears is compared in the paper, a calculating method of contact stress for non-circular gears by using equivalent gears is researched, and computing formulas of power and rotation speed for equivalent gears are deduced. A numerical simulation of contact stress for non-circular gears has also been conducted based on the finite element method. By the comparison of fitting curves, the feasibility of using equivalent gears instead of non-circular gears to calculate the contact stress is testified. 展开更多
关键词 non-circular gear contact stress equivalent gear calculating method
下载PDF
上一页 1 2 204 下一页 到第
使用帮助 返回顶部