Research of Algorithm for Judgement of Joint Elongation of Conveyer Belt

By analyzing the feature of the joint image of the conveyer belt with steel ropes, a quick judgement algorithm based on the gradient search for the joint ’s elongation is put forward. And at the same time its experiment result is also given in this paper.

A X-ray Non-destructive Testing System for Mine Conveyer Belt

A system making use of X--ray projection image to make non--destructive testing of mine conveyer belt has been developed. In the system, an one--dimensional photoelectric diode array is used to receive the X--ray projection image signals and convert them into electric signals. The principle of signal conversion is introduced and the prototype of this system is presented in this paper.

Airtight negative pressure dust-control technology and application of transpersite in the coal conveyer belt system

Presented a new coal dust control program that was airtight negative pressure dust-control technology at the transpersite,combining with analysis with the movement of air currents and numerical simulation of gas-solid flow at the transpersite,and proved the mechanism of precipitation and proliferation for coal dust-controlt in theory.The technol- ogy has made good economic results at the Heidaigou Clean Plant,not only dust concen- tration control within 10 mg/m^3 to the work site,but also substantial energy savings and cost savings.

A New Joint Elongation Detection Algorithm of the Conveyer Belt

There is a considerable interest in the image processing method of the joint of the conveyer belt with steel ropes.This paper presents a significant development of the joint's elongation judgment based on template matching and statistics which provides more accurate local information compared to the algorithms in the references,and shows a reliable,real-time performance.

Principles of X-Ray Non-Destructive Testing for Steel Wire Ropes in Conveyer Belt

The principles of X-ray Non-destructive testing (NDT) for steel wire ropes buried in conveyer belt is described in the paper. The mathematical model for calculating the effective cross section of wire ropes has been developed. The test data on steel wire rope samples of various types are presented,which have been compared with the National Standard. And this calculation model for the effective cross section is very important to the prediction system for transverse failure of conveyer belt.

NOVEL REALIZATION OF FIRST-ORDER ALL-PASS NETWORKS USING CURRENT CONVEYER

Two novel networks for realizing first-order all-pass transfer functions are intro-duced. The networks use a current conveyer, a buffer and only three passive elements, and theyexhibit a high input impedance.

Numerical Simulation of Gas-Solid Flow Processes in an Ash Conveying Pipeline with Multiple Feeds

Pneumatic conveying technology,as an efficient material transportation method,has been widely used in various industrial fields.To study the powder transportation in horizontal ash conveying pipes,this study relies on the Computational Particle Fluid Dynamics(CPFD)numerical method.The characteristics of the gas-solid two-phase flow under continuous air supply conditions are analyzed,and the effects on particle movement of factors such as feed port spacing,inlet air velocity,and the number of discharge ports are explored accordingly.The research results show that when the inlet velocity is 5 m/s,adjacent discharged particles come into contact after 8 s.As the inlet air velocity increases,the contact time between adjacent discharge ports is shortened.When the feed port spacing increases from 0.5 to 2 m,the dust accumulation thickness decreases by about 0.6 times.Additionally,when the spacing reaches a certain value,the rate of decrease in dust accumulation thickness begins to diminish.

Parametric resonance of axially functionally graded pipes conveying pulsating fluid

Based on the generalized Hamilton's principle,the nonlinear governing equation of an axially functionally graded(AFG)pipe is established.The non-trivial equilibrium configuration is superposed by the modal functions of a simply supported beam.Via the direct multi-scale method,the response and stability boundary to the pulsating fluid velocity are solved analytically and verified by the differential quadrature element method(DQEM).The influence of Young's modulus gradient on the parametric resonance is investigated in the subcritical and supercritical regions.In general,the pipe in the supercritical region is more sensitive to the pulsating excitation.The nonlinearity changes from hard to soft,and the non-trivial equilibrium configuration introduces more frequency components to the vibration.Besides,the increasing Young's modulus gradient improves the critical pulsating flow velocity of the parametric resonance,and further enhances the stability of the system.In addition,when the temperature increases along the axial direction,reducing the gradient parameter can enhance the response asymmetry.This work further complements the theoretical analysis of pipes conveying pulsating fluid.

Nonlinear dynamics of a circular curved cantilevered pipe conveying pulsating fluid based on the geometrically exact model

Due to the novel applications of flexible pipes conveying fluid in the field of soft robotics and biomedicine,the investigations on the mechanical responses of the pipes have attracted considerable attention.The fluid-structure interaction(FSI)between the pipe with a curved shape and the time-varying internal fluid flow brings a great challenge to the revelation of the dynamical behaviors of flexible pipes,especially when the pipe is highly flexible and usually undergoes large deformations.In this work,the geometrically exact model(GEM)for a curved cantilevered pipe conveying pulsating fluid is developed based on the extended Hamilton's principle.The stability of the curved pipe with three different subtended angles is examined with the consideration of steady fluid flow.Specific attention is concentrated on the large-deformation resonance of circular pipes conveying pulsating fluid,which is often encountered in practical engineering.By constructing bifurcation diagrams,oscillating shapes,phase portraits,time traces,and Poincarémaps,the dynamic responses of the curved pipe under various system parameters are revealed.The mean flow velocity of the pulsating fluid is chosen to be either subcritical or supercritical.The numerical results show that the curved pipe conveying pulsating fluid can exhibit rich dynamical behaviors,including periodic and quasi-periodic motions.It is also found that the preferred instability type of a cantilevered curved pipe conveying steady fluid is mainly in the flutter of the second mode.For a moderate value of the mass ratio,however,a third-mode flutter may occur,which is quite different from that of a straight pipe system.

天然输水河道潜水层土体渗透系数随机分布特性

清水河天然河道两侧潜水层结构属冲洪积地层,具有明显的沉积韵律,河道及调蓄水库存在不同程度渗漏,直接影响输水流量和地下水补给量。引入随机理论探究河道典型潜水层土层渗透系数的分布规律,并利用渗透系数密度分布函数得到土层组合渗透系数,对比分析了不同渗透系数组合下河道渗流量的变化,结果表明:输水河道潜水层土体黏粒含量与渗透系数相关性显著;粉质黏土、重粉质壤土渗透系数呈指数分布,壤土、砂壤土渗透系数呈t分布;基于各土层渗透系数分布函数,选取3种渗透系数组合计算的河道单侧年渗流量变幅较大,土层渗透系数随机性对渗流量影响十分显著。

Flow characteristics and Shannon entropy analysis of dense-phase pneumatic conveying under high pressure

Experiments of dense-phase pneumatic conveying of pulverized coal using nitrogen are carded out in an experimental test facility with the conveying pressure up to 4. 0 MPa and the gas-solid ratio up to 450 kg/m^3. The influences of different conveying differential pressures, coal moisture contents, gas volume flow rates and superficial velocities on the solid-gas ratios are investigated. Shannon entropy analysis of pressure fluctuation time series is developed to reveal the flow characteristics. Through investigation of the distribution of the Shannon entropy under different conditions, the flow stability and the evolutional tendency of the Shannon entropy in different regimes and regime transition processes are discovered, and the relationship between the Shannon entropy and the flow regimes is also established. The results indicate that the solid-gas ratio and the Shannon entropy rise with the increase in conveying differential pressure. The solid-gas ratio and the Shannon entropy reveal preferable regularity with gas volume flow rates. The Shannon entropy is different for different flow regimes, and can be used to identify the flow regimes. Both mass flow rate and the Shannon entropy decrease with the increase in moisture contents. The Shannon entropy analysis is a feasible approach for researching the characteristics of flow regimes, flow stability and flow regime transitions in dense-phase pneumatic conveying under high pressure.

刮板输送机半联轴器结构研究与应用

阐述了研发新结构半联轴器的背景和必要性,通过对半联轴器进行结构分解、列表分析,把整体铸造半联轴器分成齿瓣和轴套两部分,研发了铸焊结构半联轴器。通过焊缝强度校核和有限元分析计算,铸焊结构半联轴器的强度可以满足要求。铸焊结构半联轴器容易实现标准化,并且具有良好的工艺性,从根本上解决了整铸半联轴器铸造缺陷多的行业难题,值得推广使用。

矿用刮板输送机链轮更换修复评价方法

【目的】刮板输送机链轮的过度磨损、超寿命工作情况会导致卡链、断链等故障,对输送设备的正常运行造成不利影响。为了指导用户及时更换不宜继续使用的链轮,降低设备故障的发生率,提出一种矿用刮板输送机链轮更换修复评价方法。【方法】基于Archard磨损理论,对链轮的淬火硬度层的硬度特性进行研究,对圆环链传动系统在链轮不同磨损程度下的啮合传动过程进行动力学仿真分析,并对刮板输送机的动态特性进行试验,以验证仿真分析的准确性。【结果】结果表明,链轮链窝磨损深度达到最大淬火硬度层深度时,链轮的性能显著下降,应该考虑更换链轮;圆环链传动系统出现速度波动、接触力和拉力异常增加的情况时,也应及时更换链轮,以确保设备的稳定运行。所提方法为刮板输送机链轮的维护和更换提供了依据。

长距离输水工程埋地镇墩设计和稳定性分析

管道安全是长距离输水工程设计中的重点,而镇墩在维持管道安全稳定方面发挥着重要作用。本文结合某长距离输水工程,阐述了管道沿线的地质情况,通过对管线节点处布置的水平镇墩进行稳定性计算分析,发现镇墩的抗滑、抗倾覆均满足要求的结论,但低液限黏土处的镇墩地基可能会出现失稳。因此,对该处的镇墩地基以砂砾石进行了1~2m的换填,以此修正地基承载力,保证镇墩安全性,同时结合基本资料与管道运行情况,对镇墩的体型和布置进行设计优化,可为同类工程提供参考。

长距离深埋输水隧洞TBM施工期围岩变形量测方法

长距离深埋输水隧洞越来越多地采用TBM开挖施工方式,TBM开挖过程中施工期隧洞围岩变形收敛监测和松动圈范围量测是评判围岩变形情况的重要指标,是优化设计、优化施工程序、指导施工的重要依据。在TBM施工过程中受机械设备空间限制影响,常规围岩变形收敛监测和松动圈量测并不能很好发挥监测作用。文章在长距离输水隧洞TBM开挖施工过程中,根据现场实际情况对施工期围岩变形收敛及松动圈范围量测各类方法进行对比探讨。

Drilling Power Consumption and Soil Conveying Volume Performances of Lunar Sampling Auger

The sampling auger used in lunar sampling and return mission is to transmit power and convey soil, and its performance is the key factor of the whole mission. However, there is currently a lack of the optimization research on soil conveying volume and power consumption models in auger structure design. To provide the drilled object, the simulation lunar soil, whose physical and mechanical property is the same as the real soil, is made by reducing soil void ratio. The models are formulated to analyze the influence of auger structure parameters on power consumption and soil conveying volume. To obtain the optimized structure parameters of auger, the multi-objective optimization functions of the maximum soil conveying volume and minimum power consumption are developed. To verify the correctness of the models, the performances of different augers drilling simulation soil are tested. The test results demonstrate that the power consumption of optimized auger is the lowest both in theory and test, and the experimental results of soil conveying volume are in agreement with theoretical analysis. Consequently, a new method for designing a lunar sampling auger is proposed which includes the models of soil conveying volume and transportation power consumption, the optimization of structure parameters and the comparison tests. This method provides a reference for sampling auger designing of the Chinese Lunar Sample Mission.

Dynamic Characteristics of Marine Risers Conveying Fluid

The lateral vibration differential equation for a marine riser conveying fluid is derived by use of the small deflection theory, and the effect of internal flow velocity and top tension on the natural frequency of the riser is studied by use of FEM. At the same time, the preliminary relationship between the natural Frequency and riser span under different internal flow velocities is obtained, the effect of riser supports on the vibration frequency is computed. It is found that the natural frequency of the marine riser increases with the increase of top tension, however decreases with the increase of internal flow velocity. In addition, the Frequency decreases drastically with the increase of riser span.

DIFFERENTIAL QUADRATURE METHOD TO STABILITY ANALYSIS OF PIPES CONVEYING FLUID WITH SPRING SUPPORT

It is a new attempt to extend the differential quadrature method(DQM) to stability analysis of the straight and curved centerlinepipes conveying fluid. Emphasis is placed on the study of theinfluences of several parameters on the critical flow velocity.Compared to other methods, this method can more easily deal with thepipe with spring support at its boundaries and asks for much lesscomputing effort while giving ac- ceptable precision in the numericalresults.

Three-dimensional dynamics of supported pipes conveying fluid

This paper deals with the three-dimensional dynamics and postbuckling behavior of flexible supported pipes conveying fluid, considering flow velocities lower and higher than the critical value at which the buckling instability occurs. In the case of low flow velocity, the pipe is stable with a straight equilibrium position and the dynamics of the system can be examined using linear theory. When the flow velocity is beyond the critical value, any motions of the pipe could be around the postbuckling configuration(non-zero equilibrium position) rather than the straight equilibrium position, so nonlinear theory is required. The nonlinear equations of perturbed motions around the postbuckling configuration are derived and solved with the aid of Galerkin discretization. It is found, for a given flow velocity,that the first-mode frequency for in-plane motions is quite different from that for out-of-plane motions. However, the second-or third-mode frequencies for in-plane motions are approximately equal to their counterparts for out-of-plane motions, keeping almost constant values with increasing flow velocity. Moreover, the orientation angle of the postbuckling configuration plane for a buckled pipe can be significantly affected by initial conditions, displaying new features which have not been observed in the same pipe system factitiously supposed to deform in a single plane.

THE DYNAMIC BEHAVIORS OF VISCOELASTIC PIPE CONVEYING FLUID WITH THE KELVIN MODEL

Based on the differential constitutive relationship of linearviscoelastic material, a solid-liquid coupling vibration equation forviscoelastic pipe conveying fluid is derived by the D'Alembert'sprinciple. The critical flow velocities and natural frequencies ofthe cantilever pipe conveying fluid with the Kelvin model (flutterinstability) are calculated with the modified finite differencemethod in the form of the recurrence for- mula. The curves betweenthe complex frequencies of the first, second and third mode and flowvelocity of the pipe are plotted. On the basis of the numericalcalculation results, the dynamic behaviors and stability of the pipeare discussed. It should be pointed out that the delay time ofviscoelastic material with the Kelvin model has a remarkable effecton the dynamic characteristics and stability behaviors of thecantilevered pipe conveying fluid, which is a gyroscopicnon-conservative system.