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Self-locking clamping device is an important part of self locking wind power hydraulic cylinder. When the wind power system is shut down, the hydraulic cylinder must be reliably locked. This paper mainly studies the principle of self-locking device, the calculation of clamping force, the performance factors and the analysis of the elastic deformation force of the lock ring in order to meet the performance requirements of hydraulic cylinder in the process of wind system lock.

A new type of multi-footed wheel walking system is designed to break the limitations of the existing walking system. The multi-footed wheel can be used in a variety of complex terrain and can better protect the vegetation on the ground. In this paper, we established a mathematical model and analyzed the mechanics theory of the multi-footed wheel. At the same time, structural analyses of key parts were done using workbench and the rationality and safety of the structure was verified by the studies above.

In process of thermal vacuum test of spacecraft, the molecular contamination can have severe effects on performance and reliability of optical payload. In this article, we analyzed the contamination transport mechanism, simplified boundary conditions and input parameters based on physical understanding. We employed the Direct Simulation Monte-Carlo method to simulate the return flux of molecular contamination scattered by residual gas molecules in thermal vacuum tests of solar array and whole satellite. The results of simulation show that the return flux cannot be ignored, and its highest value would be 0.004. This would help the contamination control of spacecraft design, manufacture, test, and on-orbit operation.

The paper presents numerical simulation of the vortex in a submersible axial flow pump impeller using OpenFoam code. A mixture assumption and a finite rate mass transfer model were introduced to analyze vortex. The finite volume method is used to solve the governing equations of the mixture model and the pressure-velocity coupling is handled via a Pressure Implicit with Splitting of Operators (PISO) procedure. Simulation results have shown that the cavitation may occur on the lower portion of impeller suction side. And the blade channel vortex will be formed in the impeller. It can induce the pressure pulsation in the impeller and can result in reduced efficiency of the submersible axial flow pump.

The paper presents the numerical analysis of erosive wear on the guide vanes of a Francis turbine using CFD code. The 3-D turbulent particulate-liquid two-phase flow equations are employed in this study. The computing domain is discretized with a full three-dimensional mesh system of unstructured tetrahedral shapes. The finite volume method is used to solve the governing equations and the pressure-velocity coupling is handled via a Pressure Implicit with Splitting of Operators (PISO) procedure. Simulation results have shown that the volume fraction of sand at the top of the guide vanes is higher than others and the maximum of volume fraction of sand is at same location with the maximum of sand erosion rate density. The erosive wear is more serious at the top of the guide vanes.

This paper is concerned with a new model reduced method based on optimal large truncated low-dimensional dynamical system, by which the solution of linear partial differential equation (PDE) is able to be approximate with highly accuracy. The method proposed is based on the weighted residue of PDE under consideration, and the weighted residue is used as an alternative optimal control condition (POT-WR) while solving the PDE. A set of bases is constructed to describe a dynamical system required in case. The Lagrangian multiplier is introduced to eliminate the constraints of the Galerkin projection equation, and the penalty function is used to remove the orthogonal constraint. According to the extreme principle, a set of the ordinary differential equations is obtained by taking the variational operation on generalized optimal function. A conjugate gradients algorithm on FORTRAN code is developed to solve these ordinary differential equations with Fourier polynomials as the initial bases for iterations. The heat transfer equation under a potential initial condition is used to verify the method proposed. Good agreement between the simulations and the analytical solutions of example was obtained, indicating that the POT-WR method presented in this paper provides the most effective posterior way of capturing the dominant characteristics of an infinite-dimensional dynamical system with only finitely few bases.

The transient vortex structure evolution process of two-dimensional flow in a driven square cavity with one moving end was studied. The time curves of flow field variables, the flow patterns of different specific moments and the required times of flow field from static to statistical steady state were comparatively analyzed for different Reynolds numbers. Transient simulating results show that the nascent vortices always appear near the boundaries in the initial driving stage, then gradually move away from the boundaries to form a large vortex almost occupying entire cavity and two secondary vortices in left and right corners of the cavity bottom. The greater the Reynolds numbers, the longer the required times of the flow field reaching by the statistical steady state, also, the more complex of the vortex structure evolution.

Taking a hydropower station as the research object, the establishment of a numerical model that contains the full passage Tubular Turbine is given. Based on the transient incompressible N-S equations, a three-dimensional unsteady flow research is conducted. Numerical simulation of steady turbulent flow channel is calculated as the initial condition, the detached eddy simulation (DES) and slip grid technology are adopted to simulate the static-dynamic interference in the unsteady turbulent flow, The instantaneous pressure distribution in full channel and vorticity distribution of the representive section are obtained, so the three-dimensional transient vortex structures in full flow channel of the hydraulic turbine are captured. These studies aiming to explore the mechanism for the formation of vortex-induced vibration of hydro-turbine are valuable for the engineering reference.

We use deep max-pooling convolutional neural networks to address a problem of neuroanatomy, namely, the automatic segmentation of cerebral cortex structures of laboratory rat depicted in stacks of Two-photon microscopy images and detect the change areas when stimulation occurs. We classify each pixel in the image by training a CNN network, using a square window to predict the probability of the central pixel for each class. After classification, we perform the post-processing on the output produced by CNN. At last, we depict the areas that we interested through a threshold value.

The vortex structure of two-dimensional flow in a cavity is calculated using the differential quadrature method. The numerical simulation focuses on investigating the effects of Reynolds number on vortex structure evolution of the flow in a square cavity with two opposite and equal speed moving lids. The streamline patterns and bifurcation diagrams are determined. The numerical results show that the flow in the cavity takes on the streamline pattern of completely symmetric vortex structure when the Reynolds number approaches zero. With the Reynolds number increasing, the sizes and center positions of the sub-vortexes appear to be affected, whereas the saddle point is still located at the cavity center, resulting in a skewed flow pattern in the cavity. It is observed that one large vortex occupies the entire cavity and the shape of the large vortex becomes more circular after a critical value of the Reynolds number is exceeded. If the Reynolds number is increased further, two secondary eddies emerge simultaneously on the upper left corner and the lower right corner near the sidewalls. The center of the large vortex is invariably located at the cavity centre. For different Reynolds numbers, the streamline patterns are symmetric about the cavity center which is always a stagnation point.

In this paper the author introduced the application of computer drawing technology in sport drawing, the function and the skill tips of usual drawing tools. Also the teaching organization chart and sport bogdy drawing were put into drawing in practice, which soled the difficulties in writing teaching plans and teaching in classes. In this way, the study difficulty was reduced, and the time spent on mastering an action was shortened. Therefore the teaching result and quality was greatly improved, which promoted the application of computer in sport and enriched the function of sport drawing.

Parameterized model of combine harvester frame is created using the DM module of ANSYS Workbench in this paper. Analysis on the strength and stiffness of the frame is implemented to estimate its safety and economy. According to the analysis result, optimization is made to save material appropriately. Modal analysis of the frame is proceeded to study its natural frequency and compare it with external excitation frequency.

The paper presents the re-entrant jet analysis of cavitating turbulent flow on a hydrofoil. Analysis was performed by OpenFOAM code. A mixture assumption and a finite rate mass transfer model were introduced. The finite volume method is used to solve the governing equations of the mixture model and the pressure-velocity coupling is handled via a Pressure Implicit with Splitting of Operators (PISO) procedure. The result of numerical simulation clearly explained the mechanism of re-entrant jet and quasi-periodic law of cavitating flow on a hydrofoil.

The inverted pendulum system is a high order, strong coupling, multi-variable and absolutely unstable nonlinear system. Its optimal control has been the hotspot in the field of study. A new two degree of freedom model driven PID control system is introduced in this paper.It will state the structure of the control technology and design steps.The control technology is applied to control linear inverted pendulum in this paper. The simulation results prove that two degree of freedom model driven PID control system has the feasibility and superiority.

In this paper, the generator included typical automatic voltage regulation (AVR) and power system stabilizer (PSS) SCR excitation system is taken as the research object, The Hamiltonian energy function and its general Hamilton control model are analyzed, on the basis of the five order Hamilton system model, positive definite conditions of the damping matrix R(x) was derived, and the system dissipation characteristics was analyzed. Using the Hamilton energy design method, the control strategy of system was designed, under the above control, the system is finite-gain L2 stable when external disturbance occurs.

In the paper, the stability of the double-walled carbon nanotubes (DWCNTs) under the initial axial stress are studied. Galerkin and harmonic balance method are used to analyze the relation between the amplitudes and the frequencies of the tubes. The results show that the critical initial stress plays a significant control role in the amplitude-frequency curves. When the initial axial stress is less than the critical initial stress, DWCNTs have twice dynamical mode transitions corresponding to twice noncoaxial vibrations, however, when the initial axial stress is larger than the critical initial stress, the topological forms of the amplitude-frequency curve are changeable, which are corresponding to coaxial vibration or three possible noncoaxial vibration type.

Based on the transient model of hydro turbine generating sets (HTGS), the integrated simulation system of HGTS is built to study shafting stability. Given different bearing stiffness, equivalent damping coefficient and mass eccentricity, the change characteristics of shafting vibration at rated angular speed in steady and maximum angular speed in transient are simulated, and which are applied to study inferences shafting parameters and angular speed on shafting vibration. Simulation results show that the relationship between shafting vibration amplitude and angular speed is linear. however, the vibration amplitude increment produced by angular speed error will be amplified while the shafting stiffness is weaker, mass eccentricity of the runner and rotor is larger.

For a high-rise complex structure built at an earthquake zone, response characteristics to an earthquake action are always needed to be as an important index to evaluate its dynamical performances. This article carried out a three-dimensional dynamical response analyses of a large-scale complex sluice-dam structure by using the software of ANSYS under a strong earthquake excitation by nonlinear finite element method. Through the analyses of the time history response of the high-rise complex structure to the specified earthquake records, the seismic performances of the structure system under consideration of the rock foundation-sluice structure-reservoir water interaction were well evaluated.

In this paper, the fluid and structure model are fully coupled and put into FSI solver to calculate simultaneously to predict vortex-induced vibration. Multiple iterative calculations are needed in each time step and the fluid and structure model perform the next step calculation until satisfy the requirement of accuracy, which is different from conventional method used to simulate VIV. The present results agree well with the experimental results of other researchers.

This paper is concerned with propagating features of pressure waves induced by water hammer in a long liquid-conveyed pipe subjected to hyper high water head. Effects of dynamically weak compressibility of the water in pipe and pipe wall elasticity on the propagating physics were investigated by comparing in-site measurements and theoretical analyses. The pressure wave form and propagating speed were significantly effected due to weak compressibility of the water and the interactions of the waves. The wave performs a strong unsteadiness while it propagates along the pipe. This study tries to explain an event with consideration of both the dynamically weak compressibility of the water in pipe and the closing features of the valves controlled actively.

Frequency influencing factors in small weak receiving power grid with wind power penetration during the disturbance of power shortage are analyzed in this paper, such as wind power penetration rate, wind turbine types, inertia control loop and wind power fluctuation. Based on the influencing factors above, in the light of the phenomenon of large dive depth and long duration of the frequency first swing after fault, the coordination scheme of load shedding and under-frequency load shedding based on the simulation system is proposed: load shedding time and load shedding ratio coordination scheme. Simulation results verify the correctness of the theoretical analysis and the rationality and feasibility of the coordination scheme proposed.

It studies the changing regulation of fast out-of-step separation criterion based on equivalent two-machine power system. Analysis of the characteristics of the caring variables of fast out-of-step separation criterion on sending end and receiving end is mentioned. In order to solve the problem that the out-of-step connecting line cannot be identified correctly apply on the criterion of the existing fast out-of-step separation if the measurement point at the receiving end, it improves the power angle and active power criterion. The simulation is carried out in our actual grid model with using BPA and the results of the simulation handled by MATLAB proves that the out-of-step of line can be distinguished by using the improved fast out-of-step separation criterion in each end of line.

In order to improve the detection accuracy of spliced images, a new blind detection based on visual saliency was proposed in this paper. Firstly, create the edge conspicuous map by an improved OSF-based method, and extract fixations by visual attention model. Then locate those fixations on conspicuous edges by conspicuous edge positioning method. Accordingly, key feature fragments can be captured. Secondly, extract Extended Hidden Markov Model features, and reduce their dimension by SVM-RFE. Finally, support vector machine was exploited to classify the authentic and spliced images. The experimental results showed that, when testing on the Columbia image splicing detection dataset, the detection accuracy of the proposed method was 96.68%.

The paper presents numerical analysis of cavitating turbulent flow in a high head Francis turbine with draft tube natural air admission at part load operation. Analysis was performed by OpenFOAM code. A mixture assumption and a finite rate mass transfer model were introduced. The finite volume method is used to solve the governing equations of the mixture model and the pressure-velocity coupling is handled via a Pressure Implicit with Splitting of Operators (PISO) procedure. The pressure distribution and the flow of air in the draft tube are analyzed in detail. Simulation results show that the pressure fluctuations on the draft tube wall can reduce with natural air admission.

The combustion process of CFBB is a system with time-varying, nonlinear, large inertia and time delay. Therefore the control effects of traditional PID control system in the CFBB plant are not satisfactory , especially the overshoot of the main steam pressure control system is very big, and the adjustment time is too long. To improve the performance of the main steam pressure control system, ADRC technology was used . The disturbed signal was added in the different operating conditions, the testing results indicated that the ADRC main steam pressure control system had more excellent performance than the convention PID method.

The paper presents numerical simulation of blade channel vortex in a low head Francis turbine using OpenFoam code. A mixture assumption and a finite rate mass transfer model were introduced to analyze blade channel vortex. The finite volume method is used to solve the governing equations of the mixture model and the pressure-velocity coupling is handled via a Pressure Implicit with Splitting of Operators (PISO) procedure. Simulation results have shown that using cavitation model to analyze blade channel vortex is very effective.

Based on the strong interaction method that combines FEM with acoustic theory, the finite element dynamic equations of spiral casing structure are built, which provides the basis for analyzing self-olsillatin characteristics of spiral casing structure. The self-olsillatin characteristics of structure are calculated with the method. The natural vibration frequencies, and mode shapes are obtained.

The paper aims at the simulation on double tank water level control based on MATLAB .Double tank water level control belongs to large time delay system. In this paper, adopted PID method to control the system, Then, fuzzy PID control method was used to adjust this second-order system. And the simulation model of this system is built with MATLAB Fuzzy and SIMULINK. And at the end, analysis the system stability ,reaction velocity and so on.

A mobile test system for solar collector is introduced in this paper. The mobile test system for solar collector is a flexible and convenient testing device. Its design is much more difficult than that of a fixed test system for solar collector, because it needs consideration so as to make the test system accurate, reduce the volume of the test system, ensure the stability of the test system, increase corresponding removed devices and so on. For an effective integration of the test system and a vehicle, this paper discusses a mobile platform and its control system. A movement control of the subsystem adopts ac servo system based on PC. The system takes LabVIEW which is used in a virtual instrument as the development platform. And it employs a state machine model to monitor the process of removing and taking back for the mobile platform.

Pure water hydraulic technology attracts more and more attention of people due to no pollution, low cost, simple system, and many other advantages. This paper compares physico-chemical properties between pure water and hydraulic oil, concludes that pure water is the ideal medium for hydraulic system. Then it discusses the development of pure water hydraulic technology, introduces the present research situation and development of pure water hydraulic components from home to abroad in the future.

In this paper, nonlinear turbine model and hydraulic system which is one penstock one machine dynamic differential equation with elastic water column are combined. Hamiltonian function of hydraulic turbine is constructed. By applying Hamiltonian orthogonal decomposition realization and dissipation realization method, generalized Hamiltonian model of hydraulic turbine is built. Connected with generator third-order Hamiltonian model of single machine infinite bus system, generalized Hamiltonian model of hydraulic generator unit is established. This paper provides certain theory basis for research operation and control dynamics mechanism of hydraulic generator unit in generalized Hamiltonian system framework.

Take generator system included AVR (automatic voltage regulator) and PSS (power system stabilizer) as an example, Using the time simulation method, Study the equivalence between the transfer function model and the equivalent circuit simulation, and establish the corresponding relations between the circuit structures, internal parameters and transfer function parameters, based on the energy of equivalent circuit, the Hamiltonian function of transfer function is derived indirectly, and the Hamiltonian model is established. The study in this paper provides a new way to establish generalized Hamiltonian model for linear system based on transfer function.

Bourdon tube has been widely used in the fluid testing so far, and this paper introduces the chemical and physical behaviors of beryllium bronze QBe2.0 detailedly which mainly makes up bourdon tube; It analyzes the influences of elastic limit in bending on bourdon tube the chemical elements and coating technology bring; Simultaneously, it focuses on the design of the base of tube and the assembly body, points out the location of bourdon tube in bourdon tube pressure gauge; and the design of this paper can guarantee the normal work of bourdon tube in the sealed environment through the theory and practice. In the process of gauge fabricating, appropriate application of bourdon tube is very important.

The hydro turbine generating sets model exists uncertainty in structure and parameters due to its complex structure and operating states multiformity. Especially, the adaptability and robustness of controller is more important for the stabilization control at equilibrium point under given output. Based on Hamiltonian control model of nonlinear hydro turbine generating sets, the L2 disturbance attenuation control is added into the stabilization control to restrain disturbance from model and structure parameters in this paper. The L2 additional control is proved to be asymptotic stability, and its control low is derived. Simulation results show that adding L2 additional control, system can stable to given equilibrium point and has more adaptability and robustness.

Based on formulas of elastic mechanics, the axisymmetric problem applied to an elastic footing is analyzed. Using Hankel transform and finite difference method, the arbitrary points’ displacement and stress solutions of the axisymmetric elastic footing problem is obtained. Compared with recursive substitution method and transfer matrix method, this method is simple because it avoids complex formulas and exponential function calculation. The half space model is more flexible to simulate an actual footing. The numerical solutions are compared with Boussinesq’s Equation and results show that finite difference method is applicable to solve axisymmetric elastic footing problem. But in the application of finite difference method, there are a few factors that could cause calculation errors. Effective measures are needed to obtain exact solutions.

Based on the theory of elastic wave in saturated soils, the vertical vibration of a rigid circular footing resting on saturated sands is studied to obtain its analytical solution of dynamic compliance coefficients. Considering the role of water in the soil, the mass-spring-damping model of saturated sands is proposed to realize a practical way for engineering. And the stiffness and damping coefficients of model are calculated by reciprocity law equation. Compared with the solution of elastic half-space with the same Poisson’s ratio, the coefficients of the saturated sands are quite large. To comply with engineering practice, the approximate formula should be modified with multiplying them by factor in the Code for Dynamic Machine Foundation Design.

The end effects of symplectic direct solution to Stokes flow in a rectangular cavity are considered. Based on establishing the dual equations for Stokes flow in Hamilton system, the non-zero eigenvalues and their eigensolutions for an anti-symmetric problem were obtained. Expanding the solutions of dual equations by non-zero eigensolutions and determining the expansion coefficients by the end boundary conditions, the decay tendency and interaction mechanism of end effects were discussed and the end boundary errors were investigated. The resultant velocity caused by tangentially driving lid is gradually decayed along the longitudinal direction of cavity. The more number of the expansion items are superposed, the more accurate the solutions are. The smaller the depth-to-width ratios are, the stronger the interference between the end velocities is. The error of ends moving in the same directions is bigger than that in opposite directions.

The earthquake-resistance performance of gravity dam is an important indicator of dam safety. The earthquake-resistance performance of non-overflow monolith for Guanyinyan gravity dam is evaluated in this paper. First of all, the three-dimensional finite element model of dam is established by ABAQUS software. And then, the seismic response of gravity dam is analyzed by nonlinear finite element method, while the concrete damage plasticity constitutive model is adopted to describe the tensile characteristic of concrete. The seismic response and the damage evolution of dam are obtained. The results show that the dam has formed a crack-like band damage area at the end of earthquake, which are located in the dam along the dam-foundation boundary near the upstream face. At last, according to the results of simulation, the safety and the damage range are investigated.

The RNG turbulence model is used to carry out the 3D steady turbulent calculation on the runner and draft tube of the Francis turbine. And the prototype of the Francis turbine is HLA351. Under 8 typical operating conditions, numerical simulation on how the runner outlet urge the vortex rope in draft tube are accomplished in this paper, and the calculation models are long blade model and mixed blade model. The results show that the runner outlet of the mixed model can lead the vortex rope location to the downstream relatively, reduce the circumfluence and cushion area and the probability of the second-vortex. What’s more, the flow pattern in mixed model is superior to the long model and that benefits the operation stability and economy of the unit.

The parameterized drafting technology an database, which is used in diagram drafting of centrifugal fan, is introduced in this paper. The parameterized drafting system for main parts of centrifugal fan is developed by VBA under the circumstances of AutoCAD 2000. The paper introduced the realizing process of drafting principle and system function in detail.

According to the complex and uncertain relationships between indexes and grades of flood hazard evaluation, as well as the deficiency of measured samples, an improved support vector machine (SVM) model was established to improve accuracy and efficiency of calculation. The function that comprehensively evaluated indexes of multi-dimensional disaster situation in one-dimensional continuous space could be realized, and effectively solved the incompatible problems of different evaluation results with single index. The results showed that the model based on improved support vector machine had a better ability of generalization and calculation speed by reduce constraint conditions. It is considered to have a good application prospect in multi-index comprehensive evaluation.