Abstract: The flow field characteristics in U-typed bend has been extensively studied for transit time ultrasonic flowmeters designing, but for the flowmeter with three-Z-shaped round pipe there is still lack of corresponding research. This paper presents a computational fluid dynamics (CFD) approach for modeling of the three-Z-shaped ultrasonic flowmeter and studying of internal fluid field characteristics based on Reynolds stress model (RSM). The fluid velocity profile in the three ultrasound path is obtained using CFD and secondary flow in cross section also is analyzed. The simulation results show that the internal flow fields in the flowmeter are not fully developed turbulence with asymmetric axial velocity distribution and dramatic changes along the flow direction, and there are obvious secondary cross flows on theirs cross-sections. The CFD simulations provide useful insights into the flow field associated with ultrasonic flowmeters design.
Abstract: Because fruit state need to be discriminate to select the different harvesting method before it is fast picked, the fruit state discrimination method was developed. Firstly, the two apple images were acquired, and then segmented by the improved OTSU dynamic threshold segmentation method. Secondly, the picking target fruit was selected based on the principle of the nearest distance to image center when there were a lot of fruits. Thirdly, the two segmented fruit images were done by the inter-frame difference method, then the target fruit state was got using the connection number discrimination to the difference image and the centroid coordinates matching discrimination to the oscillating fruit image. Lastly, the test results showed that the designed algorithm was feasible and effective for most cases in natural environment, and the discrimination time was less than 0.2s.
Abstract: The Lidar technology can quickly acquire three-dimensional information of earth surface with high precision.As a new technique of data collection acquisition,it has been gradually applied to many industry. The classification on point cloud is the premise and key step to the feature extraction and the model building of objects. Based on LiDAR 3D and ANN This paper presents a classification method mainly suitable for the urban’s typical objects. It takes the changsha city as the study area,to verify the effectiveness of this method.The result shows that,this classification method successfully classifies the categories of the ground,buildings,trees and bare lands.
Abstract: In the environment of network competition, it is a basic condition of stabilized operation to measure effectively the risk with early warning of the project of material supply chain system. From the angle of system, this paper analyzes the set of risk factors of the project of material supply chain, and provides a fuzzy method for the supply chain whole risk of measures. Making use of this method, we can acquire the valid early warning of the system risk of project of material supply chain, so as to solve the disadvantage of deviating between the risk analysis of system and node of the project of material supply chain, all which has profit to the risk managements of system effect of the project of material supply chain and the choice of cooperation contract company.
Abstract: The key of high temperature forging size measurement based on using CCD is to extract the forging contour from the complex background. According to different forging field conditions, the paper obtains the necessary and sufficient preconditions for forgings discriminated from the background by analysis on the radiation spectral character of the high temperature forgings, the reflective spectral character of the background light and the spectral response character of the color CCD. The preconditions show that only when the reflection of background light less than the radiation of the high temperature forgings can the forgings be discerned completely. This paper proposes an implementation method for size measurement. The method has the advantages of clear concept and low operation costs. It provides the theoretical basis and available way for the discrimination and size measurement of high temperature forgings based on common and special color CCD.
Abstract: Experimental equipments are designed for the zero-crossing method of dynamic laser speckles to investigate the moving nature of nanoparticles in flowing nanofluids. After the experiments the velocity of nanoparticles in flowing nanofluids is determined according to its relationship with the zero-crossing rate of speckle intensity fluctuation. The results show that the zero-crossing rate is very sensitive to the velocity of nanoparticles when the velocity of nanofluids ranges from 17.6 mm/s to 60.2 mm/s. A TEM10 mode–like laser beam is designed and taken as an incident light to detect the moving direction of nanoparticles in flowing nanofluids. The moving direction of nanoparticles is parallel to the horizontal axis of the TEM10 mode-like laser beam when the zero-crossing rate reaches maximum. Experimental results show that the moving direction of nanoparticles can also be detected by using the zero-crossing method.
Abstract: The optical joint transform correlation based on liquid crystal spatial light modulator is a fast and parallel processing technique with high efficiency, which electronic correlation processing techniques can not match with. Similar to the correlation techniques in electronics, the sampling in optical joint transform correlation is of great importance for correlation algorithm. This paper discusses the space bandwidth problem in joint transform correlation identification experiment realized by electronic-addressing liquid crystal spatial light modulator (ELC-SLM) and CCD, and analyses the relation between focal length of Fourier lens and the resolution of lockport community television (LCTV) and charge-coupled device (CCD). Using double slit, the leaves of Dendrobium huoshanense(D.huoshanense) and so on as primary signal of correlation algorithm, it discusses the lineament and size of suitable joint transform correlation (JTC) using an object image and a reference image. In the experiment nonlinear exposure of power spectrum enhances the diffraction efficiency of correlation image. Using the joint transform correlation image recognition platform in experiment, there are leading in recognition to make quantization of recognition results. This research has certain significance to the joint correlation problem about the leaf image processing of D.huoshanense.
Abstract: This paper presents a vision-related technique for 3-D position measurement. The proposed method utilizes the genetic algorithm (GA) and unprocessed grayscale image input from vision, in order to perform recognition of a target being imaged with known target object shape. The problem to recognize the target shape and simultaneous detection of the position, is converted to an optimistic problem of a model-based evaluation function, named as surface-strips model-based fitness function that consists in the computation of the brightness difference between an internal surface and a contour-strips. In order to evaluate the proposed 3-D recognition method, experiments by an unprocessed grayscale image have been input to recognize a ball in the image. The results show the effectiveness of this method for 3-D position detection.
Abstract: It investigated in an algorithm for passive ranging algorithm based on the target’s image information along with direction information. It aimed at to avoid the sick solution of the quadratic equation for distance estimation, such as the complex solution, or the negative solution, a novel one variable quadratic equation is proposed for distance estimation. In our method, the distance ratio between two sampling times could be obtained from image matching based on feature points, and combined both the space coordinate of the observer itself and direction cosine parameters of the target to the observer, a passive distance ranging equation is settled. Theoretical analysis shows that when the observer with non-zero displacement in the adjacent sampling times, this passive ranging equation could always be solvable. It illustrated by our reduced mode experiment that the proposed algorithm is simple and feasible, relative ranging error is smaller than the former quadratic equation. It confirmed that under the same observation model, if the observer itself is moving, the distance estimation would be in much simpler mathematical form.
Abstract: In this paper, we proposed the design of an FPGA-based image processing system for target locating. The locating mechanism is based on the feature line segments of target’s image. The system processes the target’s image sequence, finds and matches feature points on each image, and uses the feature points to calculate the length of feature line segments for target locating. We implemented the Speeded Up Robust Features (SURF) algorithm on FPGA hardware to extract feature points. The system has a core CPU for control and part of the mathematical computation. Custom-designed logic circuit modules are used to accelerate the feature point extraction. The system’s software is designed to work with parallel and pipeline operation. The performance test shows that the system is capable of real-time processing.