The Design of Anti-aliasing Analog Filter for Data Acquisition in the Surface Measurement

Xu Jingbo,Xu Xiaohong,Yang Pengyu,Lin Haijun,Guo Xin 보안공학연구지원센터 2014 International Journal of Signal Processing, Image Vol.7 No.5

In the surface measurement system, the data acquisition is key part and the anti-aliasing analog filter is necessary. This paper deals with the design of the anti-aliasing analog filter. Based on the principle of anti-aliasing filtering, the parameters of filter are computed, the filter circuit is designed, and the frequency characteristic is drawn. Combined with digital filter, the filtering can maintain the low frequency components very well and suppress effectively the high frequency signals in the original surface profile, which reduces the distortion caused by noise and makes the filtering effect better. This method has been applied in the surface measurement system and the actually measured data verified the performance of the filter.

A cam-quadrilateral mechanism for power transmission of a twin-rotor piston engine

Xiaojun Xu,Hao Deng,Cunyun Pan,Haijun Xu 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.3

A quadrilateral with four invariable lengths of sides has the characteristic of transforming the variation of the diagonal length to thevariation of its interior angle. Thus, the combination of two quadrilaterals with a cam forms the differential velocity drive mechanism(DVDM) of a novel twin-rotor piston engine (TRPE). The DVDM restricts the two coaxial rotors to rotate with periodical but nonuniformvelocity, and the volume of working chambers created by the adjacent vane pistons of the two rotors alternately expands and thencontracts. The volumetric change of working chambers is used to generate the four-stroke engine cycle. The kinematic model and thedetailed position, velocity, and acceleration analysis results of the TRPE are presented. The results show that this novel engine, associatedwith the advantages of higher uniformity of torque and power density due to multiple power strokes per revolution of the output shaft, hasa compact and totally balanced design.

Numerical Simulation of Inverse Diffusion Combustion and Flow Characteristics in a Trapped Vortex Combustor

Haijun Sun,Pinghua Yang,Le Tian,Yihua Xu 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.3

In this work, the cold and combustion flow characteristics of a trapped vortex combustor with inverse diffusion combustion method have been studied numerically, and the effects of four jet arrangement schemes on the vortex structure, temperature distribution, turbulence kinetic energy, OH mass fraction and combustion efficiency were compared. The results indicate that the vortex structures in cold state are basically the same with a double vortex structure for all the jet schemes. However, when the jet holes are arranged on the after-body wall, the vortex changes from a double vortex structure in cold state to a single vortex structure in combustion state, the combustion effect is not too large when the jet holes are arranged on the fore-body wall. The high-temperature distribution in cavity is mainly concentrated in the upper part, but when the jet holes are arranged on the after-body wall, the OH mass fraction distribution is higher than that when the jet holes are arranged on the fore-body wall. In addition, when the jet holes are arranged on the fore-body wall, complete combustion can be accelerated. In general, when the jet holes are arranged in the same position, the multi-jet scheme is more conducive to flame stability in cavity and the improvement of combustion and mixing performance than the coaxial jet.

Numerical Simulation of Erosive Wear on an Impact Sprinkler Nozzle Using a Remeshing Algorithm

Xu, Yuncheng,Yan, Haijun Korean Society for Fluid machinery 2016 International journal of fluid machinery and syste Vol.9 No.4

In China, agricultural irrigation water often contains a lot of suspended sediment which may cause the nozzle wear. In this study, a new numerical simulation combing the Discrete Phase Model and a remeshing algorithm was conducted. The geometric boundary deformation caused by the erosion wear, was considered. The weight loss of the nozzle, the node displacement and the flow field were investigated and discussed. The timestep sensitivity analysis showed that the timestep is very critical in the erosion modeling due to the randomness and the discreteness of the erosion behavior. Based on the simulation results, the major deformation of the boundary wall due to the erosion was found at the corners between outlet portion and contraction portion. Based on this remeshing algorithm, the simulated erosion weight loss of the nozzle is 4.62% less compared with the case without boundary deformation. The boundary deformation changes the pressure and velocity distribution, and eventually changes the sediment distribution inside the nozzle. The average turbulence kinetic energy at the outlet orifice is found to decrease with the erosion time, which is believed to change the nozzle's spray performance eventually.

The Research on Fusion and Diagnosis Method of Multi Soft Fault of Nonlinear Analog Circuit

Haijun Lin,Jiren Han,Xuhui Zhang,Jingbo Xu,Yunfeng Liu 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.11

For the single source characteristics of the insufficient problem of nonlinear analog circuit soft fault diagnosis, we propose a new method that is based on dual Wiener core for fault diagnosis of intelligent information optimization fusion[1,2,3,4,5], firstly, the incentive is Gauss white noise, after sampling we obtain the Wiener core of circuit and power which is used from the discrete Wiener core, then use the improved genetic algorithm, make the feature selection and fusion combination as an optimization problem, propose intelligent optimization fusion extraction based on the improved genetic algorithm, the circuit set total Euclidean distance as the objective function optimizes, the different information in feature layer can be organic integration, then use the BP neural network for intelligent diagnosis. Experiments show that the method can effectively improve the accuracy of the diagnosis of nonlinear multiple soft faults.

An Experimental Study of Mineral and Microstructure for Undisturbed Loess Polluted by Landfill Leachate

Haijun Lu,Shicheng Xu,Dinggang Li,Jixiang Li 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.12

To investigate the shear strength and microstructure of undisturbed loess polluted by landfill leachate, a series of laboratory tests were carried out to determine the shear strength, mineral composition, surface morphology, particle size distribution and pore characteristics of the loess. The stress-strain curve of undisturbed soil polluted by landfill leachate showed typical strain-softening behavior. The deviatoric stress, cohesion and angle of shearing resistance of undisturbed soil decreased at increased landfill leachate concentrations, decreased by 31.03%, 30.01%, respectively. But pore water pressure was positively related to leachate concentrations. The content of primary minerals remained stable, and the content of montmorillonite and illite decreased with increased leachate concentration, reduced by 26.02%, 23.93%, respectively. Soil structure changed into an unstable honeycomb structure when the leachate concentration increased. Moreover, the average particle size decreased by 62.1%, and the specific surface area increased and then stabilized at 500 ~ 650 m2/kg. The soil particles became nonuniform and porous and their sizes gradually decreased. The pore radius of soil mainly ranged from 0.02 μm to 1 μm. The maximum radius and optimal radius of the pore increased when the leachate concentrations increased.

Decision-making Study on Mechanism and Priority of Functional Objective of the Manufacturing System

Wei Xu,Qingshan Zhang,Yue Cao,Haijun Wang 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.8

The aim of this paper established priority level determines method of manufacturing system functional objective based QFD theory, priority sequence presented and the functional objective priority weights, advised manufacturing system functional objective decisions, provides technology support and application reference for system functional objective decisions.

Numerical Simulation of Erosive Wear on an Impact Sprinkler Nozzle Using a Remeshing Algorithm

Yuncheng Xu,Haijun Yan 한국유체기계학회 2016 International journal of fluid machinery and syste Vol.9 No.4

In China, agricultural irrigation water often contains a lot of suspended sediment which may cause the nozzle wear. In this study, a new numerical simulation combing the Discrete Phase Model and a remeshing algorithm was conducted. The geometric boundary deformation caused by the erosion wear, was considered. The weight loss of the nozzle, the node displacement and the flow field were investigated and discussed. The timestep sensitivity analysis showed that the timestep is very critical in the erosion modeling due to the randomness and the discreteness of the erosion behavior. Based on the simulation results, the major deformation of the boundary wall due to the erosion was found at the corners between outlet portion and contraction portion. Based on this remeshing algorithm, the simulated erosion weight loss of the nozzle is 4.62% less compared with the case without boundary deformation. The boundary deformation changes the pressure and velocity distribution, and eventually changes the sediment distribution inside the nozzle. The average turbulence kinetic energy at the outlet orifice is found to decrease with the erosion time, which is believed to change the nozzle’s spray performance eventually.

Self-microemulsifying Drug Delivery System for Improved Oral Bioavailability of Dipyridamole: Preparation and Evaluation

Feng Guo,Haijun Zhong,Jing He, Baogang Xie,Fen Liu, Helin Xu,Minmin Liu,Chunlian Xu 대한약학회 2011 Archives of Pharmacal Research Vol.34 No.7

Dipyridamole shows poor and variable bioavailability after oral administration due to pHdependent solubility, low biomembrane permeability as well as being a substrate of P-glycoprotein. In order to improve the oral absorption of dipyridamole, a self-microemulsifying drug delivery system (SMEDDS) for dipyridamole was prepared and evaluated in vitro and in vivo. The optimum formulation was 18% oleic acid, 12% Labrafac lipophile WL 1349, 42% Solutol HS 15 and 28% isopropyl alcohol. It was found that the performance of self-microemulsification with the combination of oleic acid and Labrafac lipophile WL 1349 increased compared with just one oil. The results obtained from an in vitro dissolution assay indicated that dipyridamole in SMEDDS dissolved rapidly and completely in pH 6.8 aqueous media, while the commercial drug tablet was less soluble. An oral bioavailability study in rats showed that dipyridamole in the SMEDDS formulation had a 2.06-fold increased absorption compared with the simple drug suspension. It was evident that SMEDDS may be an effective approach to improve the oral absorption for drugs having pH-dependent solubility.

Macro-Micro Mechanical Behavior of Crushable Granular Materials under Generalized Stress Conditions

Yiming Liu,Chenming Xu,Guofang Xu,Haijun Mao,Zunqun Xiao 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.5

This paper investigated the joint influence of particle crushing and intermediate principal stress coefficient on the macro and micro performances of granular assembles by using 3D discrete element method. The soil particle was modeled by crushable agglomerate. Numerical true triaxial tests with crushable agglomerates were performed. The mechanical behaviors of specimens with unbreakable agglomerates were also tested in this study. The results demonstrated that grain breakage can significantly affect the behaviors of granular soils in both macro and micro scales. Moreover, the present paper also showed that particle breakage did not influence the unique relationship between the intermediate principal stress coefficient band the deviatoric fabric of strong contacts. This can provide a good basis for developing micro-parameter-based constitutive model considering particle breakage for granular soils.