Dynamic Response on Free-Free Beam in Driving Point and Transfer Mobility Measurement under Bending Load

This paper aims to present the experimental result obtained from dynamic response on flee-flee beam in driving point and transfer mobility analysis using impact test method using hammer tips that are steel, plastic and rubber. The 8630C accelerometer and analyzer is used for data logging and for the analysis, the plastic hammer tip is chosen. The analytical and the experimental value then are compared for the free-free beam natural frequency, damping ratio, and stiffness value. As a result, the highest percentage error for natural frequency is approximated to 2.7%, the damping ratio is approximated to 3.115 × 10^-3 and the stiffness value gives the major different between the experiment value and theoretical value. Finally, this method can be used to determine the properties of a structure such as natural frequency, mode shapes, damping ration and stiffness, respectively.

Stagnation-point flow of couple stress fluid with melting heat transfer

Melting heat transfer in the boundary layer flow of a couple stress fluid over a stretching surface is investigated. The developed differential equations are solved for homotopic solutions. It is observed that the velocity and the boundary layer thickness are decreasing functions of the couple stress fluid parameter. However, the temperature and surface heat transfer increase when the values of the couple stress fluid parameter increase. The velocity and temperature fields increase with an increase in the melting process of the stretching sheet.

Analytical solution to stagnation-point flow and heat transfer over a stretching sheet based on homotopy analysis

This paper is concerned with two-dimensional stagnation-point steady flow of an incompressible viscous fluid towards a stretching sheet whose velocity is proportional to the distance from the slit. The governing system of partial differential equations is first transformed into a system of dimensionless ordinary differential equations. Analytical solutions of the velocity distribution and dimensionless temperature profiles are obtained for different ratios of free stream velocity and stretching velocity, Prandtl number, Eckert number and dimensionality index in series forms using homotopy analysis method（HAM）. It is shown that a boundary layer is formed when the free stream velocity exceeds the stretching velocity, and an inverted boundary layer is formed when the free stream velocity is less than the stretching velocity. Graphs are presented to show the effects of different parameters.

Heat transfer in boundary layer stagnation-point flow towards a shrinking sheet with non-uniform heat flux

In this paper, the effect of non-uniform heat flux on heat transfer in boundary layer stagnation-point flow over a shrinking sheet is studied. The variable boundary heat fluxes are considered of two types： direct power-law variation with the distance along the sheet and inverse power-law variation with the distance. The governing partial differential equations （PDEs） are transformed into non linear self-similar ordinary differential equations （ODEs） by similarity transformations, and then those are solved using very efficient shooting method. The direct variation and inverse variation of heat flux along the sheet have completely different effects on the temperature distribution. Moreover, the heat transfer characteristics in the presence of non-uniform heat flux for several values of physical parameters are also found to be interesting.

MHD Stagnation Point Flow and Heat Transfer over a Permeable Surface

The steady two-dimensional, laminar flow of a viscous, incompressible, electrically conducting fluid near a stagnation point with heat transfer over a permeable surface in the presence of a uniform magnetic field is considered. Taking suitable similarity variables, the governing boundary layer equations are transformed to ordinary differential equations and solved numerically by Shooting method. The effects of the suction parameter, the magnetic parameter, the Prandtl number and the Eckert number are studied on the velocity and temperature distributions.

A KY FAN MATCHING THEOREM FOR TRANSFER COMPACTLY OPEN COVERS AND THE APPLICATION TO THE FIXED POINT

In this article, a Ky Fan matching theorem for transfer compactly open covers is established. As applications, a Fan-Browder coincidence theorem, a Ky Fan best approximation theorem and a Brouwer-Schauder-Rothe type fixed point theorem are obtained.

Momentum and heat transfer of a special case of the unsteady stagnation-point flow

This paper investigates the unsteady stagnation-point flow and heat transfer over a moving plate with mass transfer,which is also an exact solution to the unsteady Navier-Stokes(NS)equations.The boundary layer energy equation is solved with the closed form solutions for prescribed wall temperature and prescribed wall heat flux conditions.The wall temperature and heat flux have power dependence on both time and spatial distance.The solution domain,the velocity distribution,the flow field,and the temperature distribution in the fluids are studied for different controlling parameters.These parameters include the Prandtl number,the mass transfer parameter at the wall,the wall moving parameter,the time power index,and the spatial power index.It is found that two solution branches exist for certain combinations of the controlling parameters for the flow and heat transfer problems.The heat transfer solutions are given by the confluent hypergeometric function of the first kind,which can be simplified into the incomplete gamma functions for special conditions.The wall heat flux and temperature profiles show very complicated variation behaviors.The wall heat flux can have multiple poles under certain given controlling parameters,and the temperature can have significant oscillations with overshoot and negative values in the boundary layers.The relationship between the number of poles in the wall heat flux and the number of zero-crossing points is identified.The difference in the results of the prescribed wall temperature case and the prescribed wall heat flux case is analyzed.Results given in this paper provide a rare closed form analytical solution to the entire unsteady NS equations,which can be used as a benchmark problem for numerical code validation.

Boundary Layer Stagnation-Point Slip Flow and Heat Transfer towards a Shrinking/Stretching Cylinder over a Permeable Surface

In this paper, the boundary layer stagnation-point slip flow and heat transfer towards a shrinking/stretching cylinder over a permeable surface is considered. The governing equations are first transformed into a system of non-dimensional equations via the non-dimensional variables, and then into self-similar ordinary differential equations before they are solved numerically using the shooting method. Numerical results are obtained for the skin friction coefficient and the local Nusselt number as well as the velocity and temperature profiles for some values of the governing parameters, namely the velocity slip parameter (α), the thermal slip parameter (β), the curvature parameter (γ) and the velocity ratio parameter (c/a). The physical quantities of interest are the skin friction coefficient and the local Nusselt number measured by f’’(0) and –θ’(0), respectively. The numerical results show that the velocity slip parameter α increases the heat transfer rate at the surface, while the thermal slip parameter β decreases it. On the other hand, increasing the velocity slip parameter α causes the decrease in the flow velocity. Further, it is found that the solutions for a shrinking cylinder (c/ac/a>0) case. Finally, it is also found that the values of f’’(0) and –θ’(0) increase as the curvature parameter γ increases.

基于Pointnet和迁移学习的苹果表型参数估算研究

[目的]为快速、准确、无损检测苹果的外部表型参数,提出了一种基于Pointnet和迁移学习的苹果表型参数估算算法。[方法]通过Kinect相机从任意角度拍摄苹果并使用直通滤波法去除背景环境数据得到只包含苹果信息的点云数据。在此基础上使用最远点采样法,获取标准输入点云,然后采用椭球曲面方程构建苹果几何模型,生成基于椭圆方程的苹果几何模型库。使用Pointnet算法训练仿真模型数据,然后通过迁移学习迁移到实测数据上去,在训练好的模型上进行微调;再经过5-折交叉验证,判定模型的鲁棒性和泛化能力,得到最终的估算模型。[结果]以均方根误差(RMSE)和决定系数(R2)评价模型结果,实测250个苹果3个角度点云共750组数据,在任意一个角度拍摄的残缺率达到50%的点云数据的条件下,该模型对苹果的直径、高度、体积3组表型参数的RMSE分别为2.247、2.275和22.780,R2分别为0.919、0.841和0.927。[结论]该算法回归效果优于传统算法,在任意角度拍摄到的残缺率达到50%的点云数据的条件下仍能很好完成外部表型参数估算。

Wavelet analysis of stagnation point flow of non-Newtonian nanofluid

The wavelet approach is introduced to study the influence of the natural convection stagnation point flow of the Williamson fluid in the presence of thermophysical and Brownian motion effects. The thermal radiation effects are considered along a permeable stretching surface. The nonlinear problem is simulated numerically by using a novel algorithm based upon the Chebyshev wavelets. It is noticed that the velocity of the Williamson fluid increases for assisting flow cases while decreases for opposing flow cases when the unsteadiness and suction parameters increase, and the magnetic effect on the velocity increases for opposing flow cases while decreases for assisting flow cases. When the thermal radiation parameter, the Dufour number, and Williamson’s fluid parameter increase, the temperature increases for both assisting and opposing flow cases. Meanwhile, the temperature decreases when the Prandtl number increases. The concentration decreases when the Soret parameter increases, while increases when the Schmidt number increases. It is perceived that the assisting force decreases more than the opposing force. The findings endorse the credibility of the proposed algorithm, and could be extended to other nonlinear problems with complex nature.

Analysis of the optical quality by determining the modulation transfer function for anterior corneal surface in myopes

AIM: To describe the characteristics of modulation transfer function (MTF) of anterior corneal surface, and obtain the the normal reference range of MTF at different spatial frequencies and optical zones of the anterior corneal surface in myopes. METHODS: Four hundred eyes from 200 patients were examined under SIRIUS corneal topography system. Phoenis analysis software was applied to simulate the MTF curves of anterior corneal surface at vertical and horizontal meridians at the 3, 4, 5, 6, 7mm optical zones of cornea. The MTF values at spatial frequencies of 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 and 60 cycles/degree (c/d) were selected. RESULTS: The MTF curve of anterior corneal surface decreased rapidly from low to intermediate frequency (0-15cpd) at various optical zones of cornea, the value decreased to 0 slowly at higher frequency (>15cpd). With the increase of the optical zones of cornea, MTF curve decreased gradually. 3) In the range of 3 mm- 6 mm optical zones of the cornea, the MTF values measured at horizontal meridian were greater than the corresponding values at horizontal meridian of each spatial frequency, the difference was statistically significant (P<0.05). At 7 mm optical zones of cornea, the MTF values measured at horizontal meridian were less than the corresponding values at vertical meridian at 10-60 spatial frequencies (cpd), and the difference was statistically significant in 25, 30, 35, 40, 45, 50 cpd(P<0.05). CONCLUSION: MTF can be used to describe the imaging quality of optical systems at anterior corneal surface objectively in detail.

Mixed convection boundary layer flow near stagnation-point on vertical surface with slip

This paper considers the steady mixed convection boundary layer flow of a viscous and incompressible fluid near the stagnation-point on a vertical surface with the slip effect at the boundary. The temperature of the sheet and the velocity of the external flow are assumed to vary linearly with the distance from the stagnation-point. The governing partial differential equations are first transformed into a system of ordinary differential equations, which are then solved numerically by a shooting method. The features of the flow and heat transfer characteristics for different values of the governing parameters are analyzed and discussed. Both assisting and opposing flows are considered. The results indicate that for the opposing flow, the dual solutions exist in a certain range of the buoyancy parameter, while for the assisting flow, the solution is unique. In general, the velocity slip increases the heat transfer rate at the surface, while the thermal slip decreases it.

A GENERALIZATION OF BROWDER'S FIXED POINT THEOREM WITH APPLICATIONS

The purpose of this paper is to obtain a generalization of the famous Browder's fixed point theorem and some equivalent forms. As application, these results are utilized to study the existence problems of fixed points and nearest points.

Analysis of prompt supercritical process with heat transfer and temperature feedback

The prompt supercritical process of a nuclear reactor with temperature feedback and initial power as well as heat transfer with a big step reactivity (ρ0>β) is analyzed in this paper. Considering the effect of heat transfer on temperature of the reactor, a new model is set up. For any initial power, the variations of output power and reactivity with time are obtained by numerical method. The effects of the big inserted step reactivity and initial power on the prompt supercritical process are analyzed and discussed. It was found that the effect of heat transfer on the output power and reactivity can be neglected under any initial power, and the output power obtained by the adiabatic model is basically in accordance with that by the model of this paper, and the analytical solution can be adopted. The results provide a theoretical base for safety analysis and operation management of a power reactor.

From "Migrant Workers Boom" to "Migrant Workers Scarcity"——Analysis of Institutional Bottleneck of Rural Surplus Labors Transfer in China

Through description of three-steps characteristic of dual economic theory and its practical significance to the process of industrialization and urbanization in China,and making comparative analysis between important criterion of "Lewis turning point" and current situation of rural surplus labors market in China,we can find that there exists a great deal of surplus labors in rural areas in our country,improvement of peasant income is the result of external interference of government,and demographic dividend in our country hasn't finished.These phenomena go against the theory of "Lewis turning point".So it can prove that "Lewis turning point" in China hasn't come yet.The paper points out the major factors of coexistence of "migrant workers scarcity" and labors redundancy in our country.The first one is structure contradiction of labors market;the second one is law of supply-demand of labors market;the third one is institutional barrier which hinders labors in free flow of census register and social guarantee.Therefore,if we want to realize successful transfer of rural surplus labors and the goal of industrialization and urbanization,we must promote upgrading of industrial structure,change the style of economic growth and realize harmonious development of regional economy in macrocosmic level;And in microcosmic level,we should eliminate institutional barrier which hinders transfer of rural surplus labors.

不同物料流对皮带机转载点的振动冲击分析与研究

选煤厂带式输送机转载点处两皮带有一定高度差,受上端面煤块大小、含水量等因素影响,会对皮带机造成不同程度的振动冲击,从而影响皮带机带身及托辊的使用寿命。为探究物料流对转载点振动冲击的影响,结合现场调研及相关理论,推出落料冲击的影响因素主要为物料流粒度级别和含水量。然后利用光纤振动传感器、数据采集卡等器材和Labview测试系统进行现场试验,将落料口下方带式输送机在不同物料流冲击下的振动信号进行采集和处理,试验结果表明,不同粒度物料流对转载点振动冲击不同,小粒度物料流对转载点的振动波形峰值为大粒度物料流的20%,自功率谱波形峰值为0.625%;不同含水量对转载点振动冲击不同,含水量少的物料流对转载点的振动波形峰值为含水量多物料流的60%,自功率谱波形峰值降低为45%。研究结果可为降低皮带机转载点振动冲击提供合理的方法。

斜巷转载点粉尘污染规律及多断面雾幕控尘技术研究

针对斜巷转载点粉尘污染严重的问题,运用COMSOL软件对棋盘井煤矿3号转载点进行了几何建模,并基于计算流体力学(CFD)粒子追踪模型、有限元法和k-ε湍流模型,计算了3号转载点风流流线分布、速度多切面分布以及粉尘粒子运动轨迹,研究了生产工作时3号转载点处风流变化及粉尘运移规律,并针对性地提出了一种多断面雾幕控尘技术。该技术基于螺旋雾幕控尘、超音速隔尘原理,可形成距离长、覆盖范围广的雾幕以最大限度包裹粉尘颗粒,实现粉尘高效净化。最后通过控尘试验及在棋盘井煤矿3号转载点现场应用,验证了该技术的高效降尘特性以及可靠性。研究结果表明:风流分布主要受皮带速度、牵引力和诱导气流的综合作用影响,沿水平和垂直方向分层分布,形成密集且平均速度为0.5 m/s的涡流;粉尘易受涡流影响向四周扩散,主要分布在下风侧,粒径为5~15μm更容易受风流牵引扩散,聚集于工人呼吸带高度,污染严重。将该技术进行控尘试验和现场应用后,全尘和呼尘降尘效率分别高达93.65%、85.59%以上。

Evaluation of the Performance of the GSSM Under Vibration Based on Normalized Point Source Sensitivity

Giant Steerable Science Mirror( GSSM) is the tertiary mirror of the Thirty Meter Telescope( TMT).To evaluate the performance of the GSSM under the mechanical vibration,the Normalized Point Source Sensitivity( PSSn) is used to understand and characterize the optical performance degradation. First and foremost,the definition of the PSSn is shown and the calculation procedure of the PSSn at the work condition where the telescope aberration is much smaller than seeing is presented to reveal the relationship between PSSn and seeing.Then,the optical degradation due to vibration is achieved by the two methods: one is the statistics moment for the arbitrary froms of vibration and other one is spectrum method for wind load. After the theoretical presence,the simulation is processed. The multi-axis-accelerometers are used to achieve the motion of the mirror. After integrated to displacement signal,the measured signal is applied to the mathematical model of the GSSM and the optical performance degradation under certain mechanical vibration can be achieved. The PSSN flows from 0.996 to 0.994 under some dynamic vibration. And then,the wind load is applied to the mathematical model using spectrum method with the PSSN flows from 0.996 to 0.991. This paper can help the system engineers to predict the performance of the GSSM in various work condition. What is more,PSSn is able to be combined just by simple multiplication,so the optical performance degradation can be easily co-considered with other error sources.

Three-dimensional magnetohydrodynamics axisymmetric stagnation flow and heat transfer due to an axisymmetric shrinking/stretching sheet with viscous dissipation and heat source/sink

The present work is concerned with the effects of viscous dissipation and heat source/sink on a three-dimensional magnetohydrodynamic boundary layer axisymmetric stagnation flow, and the heat transfer of an electrically conducting fluid over a sheet, which shrinks or stretches axisymmetrically in its own plane where the line of the symmetry of the stagnation flow and that of the shrinking （stretching） sheet are, in general, not aligned. The governing equations are transformed into ordinary differential equations by using suitable similarity transformations and then solved numerically by a shooting technique. This investigation explores the conditions of the non-existence, existence and uniqueness of the solutions of the similar equations numerically. It is noted that the range of the velocity ratio parameter, where the similarity solution exists, is increased with the increase of the value of the magnetic parameter. Furthermore, the study reveals that the non-alignment function affects the shrinking sheet more than the stretching sheet. In addition, the numerical results of the velocity profile, temperature profile, skin-friction coefficient, and rate of heat transfer at the sheet are discussed in detail with different parameters.

Transient Hydromagnetic Stagnation-Point Flow across a Vertical Surface with Partial Slip in a Chemically Reactive Medium

A numerical study of partial slip boundary condition is investigated. The stagnation-point flow problem involving some physio-chemical parameters has been elucidated. The process involves developing a multivariate mathematical model for the flow and transforming it into a coupled univariate equation. Key parameters of interest in the study are the buoyancy force, the surface stretching, the unsteadiness, the radiation, the dissipation effects, the slip effects, the species reaction and the magnetic field parameters. It is concluded that the impact of physio-chemical factors significantly alters the kinematics of the flow in order to optimally achieve desired product characteristics.