Papers by Keyword: Measurement

Abstract: Thermoelectric generator is solid-state device which convert temperature difference, ∆T into electrical energy based on Seebeck effect phenomenon. The device has been widely used in self-powered system applications. This paper focuses on presentation of methodology for characterizing thermoelectric generators. The measurement of its behavior is performed by varying load resistances. A standard module of thermoelectric generator (TEC1-12710) is used in examination and an instrument setup consists of controllable heat source, controllable cooler, personal computer, data logger MCC DAQ USB-1208LS equipped with two sets of K-type thermocouples. The experiment is performed by measuring output voltage and output current in 4 values of temperature gradient by applying 10 values of resistive loads connected to the thermoelectric output wires. The common parameters studied in this research are output voltage, current and power. Generally, the relationship between parameters agrees with the basic theory and the procedure can be adopted for characterizing other type of thermoelectric generator.

Abstract: In this paper it is presented an analysis regarding the influence of temperature from the chipping area, in the machining by centerless grinding with transversal feed. The temperature influences the machining precision, the additional loads of the machine – device – tool – part elastic system and the measurement accuracy. These influences have direct impact on the precision and quality of the machined parts executed using the centerless grinding process.

Abstract: In this paper, we use a compensation method of the measured short interval to improve the measurement accuracy by two groups of multiplex. By using two groups of multi-channel monostable pulse signal as a compensation signal, we respectively compensate time difference between the starting/ending measured short time interval and the reference signal. Pulse width of each compensation signal is uniform increasing and incremental sum is a reference signal cycle. We select the average value of two compensation signals pulse width as the beginning and the end of the time difference when the reference signal value jumps after compensation. Then according to the number of reference signal and two compensation time difference we can obtain measured short time interval. Error analysis and evaluation of uncertainty measurement show that the precision of this method is decided by pulse width increment of adjacent compensation signals. The experimental data shows that the method effectively reduces the measurement error of one reference signal cycle in the measurement of time interval.

Abstract: Most embedded systems are real-time systems, so real-time is an important performance metric for embedded systems. The worst-case execution time (WCET) estimation for embedded programs could satisfy the requirement of hard real-time evaluation, so it is widely used in embedded systems evaluation. Based on sufficient survey on the progress of WCET estimation around the world, it proposes a new classification of WCET estimation. After introducing the principle of WCET estimation, it mainly demonstrates various types of technologies to estimate WCET and classifies them into two main streams, namely, static and dynamic WCET estimations. Finally, it shows the development of WCET analysis tools.

Abstract: The particle concentration distribution in the foundry is very important not only for the occupational health of foundry workers but also for creating green foundry industry. In this study, the authors measured the particle concentration distribution in a foundry workshop, and analysis the characteristics of foundry dust pollution with the consideration of total dust control in the recent foundry industry. The results show that the concentrations of PM10 and PM2.5 are high in the central and low in the ends of the workshop. It is about 54% of all test sites with higher concentration of PM10 and PM2.5 than the limit values of national standards. However, the PM4 concentrations of about 31% test sites are higher than limit of national standards. It is obviously that sandfilling process, cavity repair and sweeping in mold making process can produce a lot of dust. This study may provide guidance for the foundry pollution control engineering and workshop operation management system.

Abstract: The surface of the grinding wheel and the conditions under which it is prepared has a profound influence upon the grinding performance as characterised by the grinding forces, power consumption, cutting zone temperature and component surface finish. Only by having a clear understanding of the wheel topography can the interaction of the grinding wheel surface with the workpiece be fully understood. Two dimensional measurements or profilometry, while being a relatively quick measurement to perform, suffers from information quality issues due to the subjectiveness of the profile location as well as questions regarding how representative a profile is of a three-dimensional real surface. While profilometric measurement has long been standardised in the form of various international standards, topographic standards have only recently been agreed upon and formalised as ISO 25178. In this paper a comprehensive approach to wheel topographic characterisation will be undertaken. Factors such as measurement strategy, filtering, active grain identification as well as the fidelity of surface replication will be considered. The paper will propose a recommended measurement strategy and surface parameter set deemed sufficient to provide a comprehensive understanding of the grinding wheel topography.

Abstract: Yihe River No. 2 extra large bridge is taken as an example in this paper, from the establishment of control network, the pile foundation to the lofting of caps and other structures, this paper introduces the measurement methods used in the extra large bridge construction process, and how to assure the accuracy of bridge construction in the measurement as well, which provides reference for similar projects.

Abstract: According to the measurement problem of aircraft parts at maintain field, a measurement system based on industrial robot is proposed in this paper. An industry robot which carries an electronic lever indicator with communicating function to sample data, serves as main measurement actuator. The aircraft part is fixed on a revolving table, and the whole part can be measured on equivalent rotated place. Some key points, such as the kinematics model of the system, the calibration of the system and measuring approach are discussed. The experimental results demonstrate that the system is more flexible and more efficient and fit better in the maintain field with respect to traditional measurement methods.

Abstract: In this paper, combined with the first phase of wuhan rail transit line No. 4 line network management service center B building curtain wall engineering practical problems, Auto CAD auxiliary polar coordinate method is used to rapidly and accurately complete curved plane positioning pay-off, forming method, this method has been applied in several projects, produced good economic and social benefits.

Abstract: Optical encoders have been used for decades as displacement measuring devices. As far as image measurement is concerned, CCD and CMOS are gradually used in metrology fields. In practice, performance of image ultraprecise optical encoders are related to environmental temperature, humidity, data processor speed, and vibration, thus measurement precision of encoders will be affected, and these factors limit their usage scale. Among these factors, the vibration is the largest effect factor. Here, a new experiment system was built to study vibration effect of measurement. Experiments indicated that the effects of vibration mainly exist in two aspects. Firstly, vibration induced deformation of glass grating, so distance of adjacent grating lines got uncertain. Secondly, random vibration affected CMOS image sharpness, and it reduced accuracy of encoding and decoding. Finally, some methods are provided to reduce the vibration of the grating encoder.