TOUCH TRIGGER PROBE MEASUREMENT ACCURACY OF ASPHERICAL MIRROR DURING FINE LAPPING PROCESS

2005 ◽  
Vol 41 (08) ◽  
pp. 228 ◽  
Author(s):  
Haobo Cheng
Keyword(s):  
Measurement Accuracy ◽  
Probe Measurement ◽  
Touch Trigger Probe ◽  
Aspherical Mirror

Study on the Stability of Micro-Area Sheet Resistance at Testing a Large Silicon Wafer when Probes Vacillated

2013 ◽  
Vol 303-306 ◽  
pp. 399-402 ◽  
Author(s):  
Xin Fu Liu ◽  
Zhi Hui Zhu ◽  
Ru Qing Zhang ◽  
Run Li Zhang
Keyword(s):  
Sheet Resistance ◽  
Silicon Wafer ◽  
Measurement Accuracy ◽  
Probe Measurement ◽  
Measurement Technology ◽  
Calculation Formula ◽  
Basic Principles ◽  
Basic Concepts ◽  
The Stability ◽  
The Impact

This article briefly elaborated the basic concepts of the probe vacillated at testing a large silicon wafer with square four point probe equipment. The importance of the micro-area’s sheet resistance is discussed and the basic principles of four point probe measurement technology are analyzed. Some factors that affect the measurement accuracy are studied, and interference can be avoided while measuring and analyzing the impact on square four point probe measurement by probe vacillate. The calculation formula of the square micro-area probe measurement is deduced when probes vacillated discretionarily. At last, an experiment was made with a small wafer sample and accurate resistivity was gotten.

scholarly journals Effects of probes with different structures on the flow field and measurement results of imported compressors

2021 ◽  
Vol 39 (4) ◽  
pp. 858-864
Author(s):  
Guanghua Zheng ◽  
Fei Shui ◽  
Jinxin Hu ◽  
Xin Liu ◽  
Huazhong Xiao
Keyword(s):  
Measurement Error ◽  
Flow Field ◽  
Flow Rate ◽  
Total Pressure ◽  
Measurement Accuracy ◽  
Probe Measurement ◽  
Pressure Probe ◽  
Temperature Probe ◽  
Measurement Results ◽  
Total Temperature

In this paper, the measurement accuracy of two different types of total pressure probe and total temperature probe in turboshaft engine compressor inlet channel and the influence of these two probes on the flow field through numerical simulation was studied. At the same time, the influence of the probe structure and installation position on probe measurement results under three typical working conditions of cruise, maximum continuous and takeoff was analyzed. The simulation results showed that the higher the engine inlet flow rate, the greater the measurement error of the probe. Comparing with the total temperature probe, the total pressure probe measurement accuracy is more influenced by the flow rate. The velocity uniformity is less affected by the engine operating conditions and is mainly related to the structure of the inserted probes. The closer the total pressure probe to the support plate, the greater the measurement error. The probe installation position has a small effect on the total pressure loss coefficient at the outlet.

On-Machine Measurement for Touch-Trigger Probes and its Error Compensation

2008 ◽  
Vol 375-376 ◽  
pp. 558-563 ◽  
Author(s):  
Xiao Ming Qian ◽  
Wen Hua Ye ◽  
Xiao Mei Chen
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Measurement Error ◽  
Error Compensation ◽  
Error Modeling ◽  
Probe Measurement ◽  
Advantages And Disadvantages ◽  
Machining Center ◽  
Touch Trigger Probe ◽  
Artificial Neural

This paper advances a method to implement the on-machine measurement (OMM) with the touch-trigger probe, also called switching probes. Some of the advantages and disadvantages for touch-trigger probe are discussed. However, the touch-trigger probe errors exist and become one of the major errors for the measurement accuracy. Major factors that influence the probe measurement have been analyzed. The basic technique of probe measurement error modeling with artificial neural network was researched, and also the probe measurement error compensation with 3-layered backpropagation artificial neural network was presented. At last in the experimental system composed of DIXI 50 machining center, Fanuc 16i control system, Blum CNC P82.046 probe and PC, valid the correlated techniques. In addition, the connection and communication between the machining center equipped with probe system and the computer have been introduced. The experiment indicated that, using the touch-trigger probe makes on-machine measurement more automatic and efficient. And by using the back-propagation neural network for error compensation make on-machine measurement more precise.

Methods for Restricting Maximum Exposure Rate in Computerized Adaptative Testing

Methodology ◽  
2007 ◽  
Vol 3 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Juan Ramon Barrada ◽  
Julio Olea ◽  
Vicente Ponsoda
Keyword(s):  
Measurement Accuracy ◽  
Computerized Adaptive Testing ◽  
Computation Time ◽  
Adaptive Testing ◽  
Exposure Rate ◽  
Control Parameters ◽  
The Impact ◽  
Two Alternatives ◽  
Selection Of ◽  
Maximum Exposure

Abstract. The Sympson-Hetter (1985) method provides a means of controlling maximum exposure rate of items in Computerized Adaptive Testing. Through a series of simulations, control parameters are set that mark the probability of administration of an item on being selected. This method presents two main problems: it requires a long computation time for calculating the parameters and the maximum exposure rate is slightly above the fixed limit. Van der Linden (2003) presented two alternatives which appear to solve both of the problems. The impact of these methods in the measurement accuracy has not been tested yet. We show how these methods over-restrict the exposure of some highly discriminating items and, thus, the accuracy is decreased. It also shown that, when the desired maximum exposure rate is near the minimum possible value, these methods offer an empirical maximum exposure rate clearly above the goal. A new method, based on the initial estimation of the probability of administration and the probability of selection of the items with the restricted method ( Revuelta & Ponsoda, 1998 ), is presented in this paper. It can be used with the Sympson-Hetter method and with the two van der Linden's methods. This option, when used with Sympson-Hetter, speeds the convergence of the control parameters without decreasing the accuracy.

Structured methods for improving flow measurement accuracy in pipelines

2020 ◽  
pp. 30-35
Author(s):  
Gurami N. Akhobadze
Keyword(s):  
Flow Measurement ◽  
Measurement Accuracy ◽  
Directional Coupler ◽  
Signal To Noise Ratio ◽  
Scattered Wave ◽  
Orthogonal Polarization ◽  
Flow Sensors ◽  
Information Signal ◽  
Mass Flows ◽  
Processing Device

In the age of digital transformation of production processes in industry and science the development and design of intelligent flow sensors for granular and liquid substances transferring through pipelines becomes more important. With this in view new approaches for improving the accuracy of microwave flowmeters are proposed. Taking into account the characteristics ofelectromagnetic waves propagating through a pipeline, a wave scattered by inhomogeneities of the controlled medium is analyzed. Features of the transformation of the polarized scattered wave limiting the geometric dimensions of the pipeline and optimizing the values of the useful scattered signal are revealed. Expediency of collection of the information signal with orthogonal polarization of the scattered wave and through a directional coupler is substantiated. The method of estimating the measurement accuracy with reference to the signal-to-noise ratio at the input of the processing device is given. The research results can be used in cryogenic machine engineering to measure volume and mass flows of liquid cryogenic products.

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