利用人体运动传感器实现智能风扇的算法与设计

现有风扇不管人体是否需要,都按照预先设定的模式运行,这使得使用者非常被动。利用单片机将人体运动传感器与温湿度传感器相结合,系统先设置26℃、26.5℃、27.3℃三种温度区间,不同温度区间与相应的风速对应,同时风扇自动校正网络时间,适时环境温度与档位相匹配,转速将根据时间划分及设置的温度区间来进行转动。再通过监测正常人在舒适环境中睡眠时身体各部位的几种体动情况,归纳出人体在冷热环境下体动时间短、周期短的特征。当使用者使用夜间智能模式后,系统自动监测周围环境温湿度情况,结合人体体动特征判断此时人体体动是否是由于冷热引起的,再根据所设温度区间及对应的时间自动向上一级或向下一级档位匹配,直到达到人体真正对风力的需求。实现真正意义上的根据人体需求的智能控制风扇,具有较高的应用意义。

Trajectory optimization for a cleaning robot for a hotline insulator

We investigated the vibration of a cleaning robot for hotline insulators, providing a flexible elevating link with a rigid moving link at the end. A Lagrange dynamic model is established based on the assumed mode method. An approach is proposed to reduce residual vibration of the flexible elevating link by optimizing acceleration of rigid link using the Pontryagin maximum principle (PMP). A numerical solution to the proposed optimization problem including a two-point boundary-value problem (2PBVP) is developed. Residual vibration of the flexible elevating link of the optimal acceleration profile is compared with that of the optimal trapezoid velocity profile. The result shows that the proposed trajectory optimization method can reduce the residual vibration more effectively.

Simulating the dynamics of fluid-cylinder interactions

We present the simulation of the dynamics of fluid-cylinder interactions in a narrow three-dimensional channel filled with a Newtonian fluid, using a Lagrange multiplier based fictitious domain methodology combined with a finite element method and an operator splitting technique. As expected, a settling truncated cylinder turns its broadside perpendicular to the main stream direction and the center of mass moves to the central axis of the channel. In the case of two truncated cylinders, they first move around each other for a while and then stay together in a "T" shape. After the "T" shape has been formed for a long enough time, we found no vortex shedding behind the cylinders. When simulating the fluidization of 60 truncated cylinders, we captured the features of interactions among fluidized cylinders as observed in experiments.

Modeling and Numerical Simulation of Yield Viscoplastic Fluid Flow in Concentric and Eccentric Annuli

Numerical solution of yield viscoplastic fluid flow is hindered by the singularity inherent to the Herschel-Bulkley model. A finite difference method over the boundary-fitted orthogonal coordinate system is util- ized to investigate numerically the fully developed steady flow of non-Newtonian yield viscoplastic fluid through concentric and eccentric annuli. The fluid rheology is described with the Herschel-Bulkley model. The numerical simulation based on a continuous viscoplastic approach to the Herschel-Bulkley model is found in poor accordance with the experimental data on volumetric flow rate of a bentonite suspension. A strict mathematical model for Herschel-Bulkley fluid flow is established and the corresponding numerical procedures are proposed. However, only the case of flow of a Herschel-Bulkley fluid in a concentric annulus is resolved based on the presumed flow stnicture by using the common optimization technique. Possible flow structures in an eccentric afinulus are presumed, and further challenges in numerical simulation of the Herschel-Bulkley fluid flow are suggested.

Motion estimation of elastic articulated objects from image contours

A new method of elastic articulated objects (human bodies) modeling was presented based on a new conic curve. The model includes 3D object deformable curves which can represent the deformation of human occluding contours. The deformation of human occluding contour can be represented by adjusting only four deformation parameters for each limb. Then, the 3D deformation parameters are determined by corresponding 2D contours from a sequence of stereo images. The algorithm presented in this paper includes deformable conic curve parameters determination and the plane, 3D conic curve lying on, parameter determination.

Inertisation options for BG method and optimisation using CFD modelling

Spontaneous combustion(sponcom) is one of the issues of concern with the blasting gallery(BG) method of coal mining and has the potential to cause fires, and impact on production and safety, greenhouse gas(GHG) emissions and huge costs involved in controlling the aftermath situations. Some of the research attempts made to prevent and control coal mine fires and spontaneous combustion in thick seams worked with bord and pillar mining methods are presented in this paper. In the study, computational fluid dynamics(CFD) modelling techniques were used to simulate and assess the effects of various mining methods, layouts, designs, and different operational and ventilation parameters on the flow of goaf gases in BG panels. A wide range of parametric studies were conducted to develop proactive strategies to control and prevent ingress of oxygen into the goaf area preventing spontaneous combustion and mine fires.

Synthesis of Multi-component Mass-exchange Networks

This paper presents a superstructure-based formulation for the synthesis of mass-exchange networks (MENs) considering multiple components. The superstructure is simplified by directly using the mass separation agents (MSA) from their sources, and therefore the automatic synthesis of the multi-component system involved in the MENs can be achieved without choosing a 'key-component' either for the whole process or the mass exchangers. A mathematical model is proposed to carry out the optimization process. The concentrations, flow rates, matches and unit operation displayed in the obtained network constitute the exact representation of the mass exchange process in terms of all species in the system. An example is used to illustrate and demonstrate the application of the proposed method.

Modeling of fluid-induced vibrations and identification of hydrodynamic forces on flow control valves

Dynamics and vibration of control valves under flow-induced vibration are analyzed. Hydrodynamic load characteristics and structural response under flow-induced vibration are mainly influenced by inertia, damping, elastic, geometric characteristics and hydraulic parameters. The purpose of this work is to investigate the dynamic behavior of control valves in the response to self-excited fluid flow. An analytical and numerical method is developed to simulate the dynamic and vibrational behavior of sliding dam valves, in response to flow excitation. In order to demonstrate the effectiveness of proposed model, the simulation results are validated with experimental ones. Finally, to achieve the optimal valve geometry, numerical results for various shapes of valves are compared. Rounded valve with the least amount of flow turbulence obtains lower fluctuations and vibration amplitude compared with the flat and steep valves. Simulation results demonstrate that with the optimal design requirements of valves, vibration amplitude can be reduced by an average to 30%.

Three-dimensional Computational Fluid Dynamics Modeling of Two-phase Flow in a Structured Packing Column

Characterizing the complex two-phase hydrodynamics in structured packed columns requires a power- ful modeling tool. The traditional two-dimensional model exhibits limitations when one attempts to model the de- tailed two-phase flow inside the columns. The present paper presents a three-dimensional computational fluid dy- namics （CFD） model to simulate the two-phase flow in a representative unit of the column. The unit consists of an CFD calculations on column packed with Flexipak 1Y were implemented within the volume of fluid （VOF） mathe- matical framework. The CFD model was validated by comparing the calculated thickness of liquid film with the available experimental data. Special attention was given to quantitative analysis of the effects of gravity on the hy- drodynamics. Fluctuations in the liquid mass flow rate and the calculated pressure drop loss were found to be quali- tatively in agreement with the experimental observations.

Potentials of Cellular Vortex Element Modeling of Fluid Flow in Confined 2D Aquifer

Numerical methods such as finite difference, finite volume, finite element or hybrid methods have been globally used to successfully study fluid flow in porous stratum of which aquifers are typical examples. Those methods involve mathematical expressions which increases computation time with requirement of specific human expertise. In this paper, numerical models for single phase flow in 1D and 2D using the conservation of mass principles, Darcy＇s flow equation, equation of state, continuity equation and the STB/CFB （stock tank barrel/cubic feet barrel） balance were developed. The models were then recast into pressure vorticity equations using convectional algorithms. Derived equations were used to formulate transport equations which resemble the conventional vorticity transport equation. Formulated numerical models were used to investigate the daily instantaneous aquifer pressure drawdowns and pressure heads for 365 days. The developed equations were subsequently solved using cellular vortex element technique. The developed computer program was used to investigate confined aquifer of dimensions 10× 10 × 75 m with single vertex image. For the aquifer rate of 0.5 m3/s, 0.1 m3/s, 0.15 m3/s, 0.2 m3/s, 0.25 m3/s, 1.0 m3/s, 2.0 m3/s, 2.5 m3/s, 3.0 m3/s, 4.0 m3/s, the respective average head drawdowns and heads were, 1.127 ±0.0141 m, 1.317 ±0.0104 m, 1.412± 0.0041 m, 1.427 ± 0.116 m,1.527 ± 0.0141 m, 2.107 ± 0.0171 m, 2.197 ±0.0191 m, 3.007±0.0171 m, 3.127 ± 0.0041 m, 3.626 ± 0.0121 m, and 25 kN/m2, 35 kN/m2, 33 kN/m2, 5 kN/m2, 6 kN/m2, 11 kN/m2, 25 kN/m2, 42 kN/m2, 50 kN/m2, 62 kN/m2, respectively. Cellular vortex technique with relative little mathematics has been established to have recorded successes in numerical modeling of fluid flow in aquifer simulation.

Kinetic Adsorption of CO2/CH4 Mixture Using 13X Zeolite： Modeling and Simulation

In this work, the separation of carbon dioxide （CO2） from （PSA） column was modeled and simulated. The adsorption kinetics the methane （CH4） using fixed bed Pressure Swing Adsorption on the 13X zeolite adsorbent was described by Linear Driving Force （LDF） model. Simulation of adsorption phenomena inside the fixed bed was implemented using Computational Fluid Dynamic （CFD） method, based on porous media concept, and the mass transfer coefficients for gas components （COz and CH4） were developed using User Defined Scalars （UDS）. The model was validated by comparing with the experimental data, which were collected based on a varied set of laboratory conditions. The prediction of the adsorption isotherm （uptake curve） and methane recovery using the simulation results exhibited a reasonable agreement with the experimental data. Moreover, the effects of feed flow rate and bed concentration evolution were investigated. The current results suggested that CFD approach is capable to predicate the hydrodynamics and adsorption phenomena in the fixed bed adsorption column.

Mathematical modeling and analysis of gas torque in twin-rotor piston engine

The gas torque in a twin-rotor piston engine(TRPE) was modeled using adiabatic approximation with instantaneous combustion. The first prototype of TRPE was manufactured. This prototype is intended for high power density engines and can produce 36 power strokes per shaft revolution. Compared with the conventional engines, the vector sum of combustion gas forces acting on each rotor piston in TRPE is a pure torque, and the combustion gas rotates the rotors while compresses the gas in the compression chamber at the same time. Mathematical modeling of gas force transmission was built. Expression for gas torque on each rotor was derived. Different variation patterns of the volume change of working chamber were introduced. The analytical and numerical results is presented to demonstrate the main characteristics of gas torque. The results show that the value of gas torque in TRPE falls to be less than zero before the combustion phase is finished; the time for one stroke is 30° in terms of the rotating angle of the output shaft; gas torque in one complete revolution of the output shaft has a period which is equal to 60° and it is necessary to put off the moment when gas torque becomes zero in order to export the maximum energy.

Test technology research and fatigue damage prediction of a car body based on dynamic simulation load spectrum

The dynamic model of a high-speed electric multiple unit(EMU)is established based on the theory of rigid-flexible coupling multi-body system dynamics.Depending on the actual operating conditions of the vehicle,there are a variety of conditions of car body load-time history.We assess ineffective amplitude omission,load spectrum extrapolation,and extreme determination through the car body load-time history,and then obtain the car body fatigue load block spectrum.Finally,we perform a fatigue strength test on the whole car body on a car body fatigue test bench.It is shown that the accelerations of the three directions of the vehicle car body increase with increasing speed.When the train passes a curve,the lateral acceleration average becomes greater.There is also an increase in the car body accelerations in three directions when the train goes through a turnout or twisted line.Under the condition of a failed spring,the vertical acceleration of the car body is obviously increased.Anti-yaw damper failure will cause a significant increase in vehicle lateral acceleration.The failure of lateral and vertical dampers on the second suspension causes an insignificant acceleration increase in three directions.The car body acceleration increases the wear-type profile relative to the original profile in various working and speed level conditions a little.The influence on the damage of vehicle car body under various working conditions is predicted according to the obtained load spectrum.

Dynamic modeling of a wave glider

We propose a method to establish a dynamic model for a wave glider, a wave-propelled sea surface vehicle that can make use of wave energy to obtain thrust. The vehicle, composed of a surface float and a submerged glider in sea water, is regarded as a two-particle system. Kane＇s equations are used to establish the dynamic model. To verify the model, the design of a testing prototype is proposed and pool trials are conducted. The speeds of the vehicle under different sea conditions can be computed using the model, which is verified by pool trials. The optimal structure parameters useful for vehicle designs can also be obtained from the model. We illustrate how to build an analytical dynamics model for the wave glider, which is a crucial basis for the vehicle＇s motion control. The dynamics model also provides foundations for an off-line simulation of vehicle performance and the optimization of its mechanical designs.

Modelling and analysis for a pilot relief valve using CFD method and deformation theory of thin plates

The current work is concerned with modelling and analysis for a pilot relief valve, thus successfully bringing a systematic method for designing and analyzing similar valves. The essence of the work is to solve two important problems, one for positions of the pilot valve influenced by flow force and the other is for the opening of the relief valve governed by a thin annular plate. The computational fluid dynamics(CFD) method is used to present the flow force. Using a series of experiments, the flow rate versus pressure drop shows the rationality of the CFD results. In order to obtain the opening of relief valve with higher accuracy, the large deflection theory of thin plates is adopted. An equivalent method for replacing the concentrated force is innovatively proposed so that all of the loads of the plates can be given by a unified expression, which reduces the number of the governing equations and intermediate boundary conditions. For presenting a very simple and reliable method for solving the governing equation, an unconstrained nonlinear optimization is innovatively introduced to solve the deflection of the thin annular plate. Being verified by finite-element method(FEM) of the relief valve, the equivalent method and optimization can solve deflection of thin plates rapidly and accurately. Reflected through a complete model for the pilot relief valve, the theoretical flow rate of the pilot relief valve is consistent with experimental conclusion. Once again, the comparisons bring us insight into the accuracy of the method adopted in the current work.

Thermal Modeling and Cooling Analysis of High-power Lithium Ion Cells

The heat generation model and three-dimensional computational fluid dynamics model for lithium ion cells were established with boundary conditions defined.In order to provide a better insight about the behaviors of high-power lithium ion cells under realistic discharge conditions,the temperature difference of the cells and an active thermal management system with a pure air-cooling mode were analyzed and predicted with the factors affecting the unevenness of temperature field discussed.The results show a significant effect of the cooling flow rate on the temperature rise of the cells for all discharge rates.Average surface temperatures are relatively uniform at lower discharge rate that makes it easier to control the temperature of the pack.Cell temperatures are expected to rise significantly toward the end of discharge and they show non-uniformity at higher discharge rates.Adequate air flow rate of active cooling is required at high discharge rate and high ambient temperature for practical pack thermal management system.

Nonlinear dynamic characteristics of magneto-rheological visco-elastomers

The smart magneto-rheological visco-elastomer (MRVE) has a promising application to vibration control.Its dynamic characteristics are described by complex moduli which are applicable to linear dynamics.However,experimental results show remarkable nonlinear relations between force and deformation for certain large deformations,and the nonlinear dynamic modeling needs to be developed.The present study focuses on the nonlinear dynamic characteristics of MRVE.The MRVE was fabricated and specimens were tested to show nonlinear mechanical properties and dynamic behaviors.The nonlinear effect induced by applied magnetic fields was investigated.A phenomenological model for the dynamic behaviors of MRVE was proposed to describe the nonlinear elasticity,linear damping and hysteretic effect,and the corresponding equivalent linear model in the frequency domain was also given for small deformations.The proposed model is applicable to the dynamics and control analysis of composite structures with MRVE.

Failure modeling of folded dielectric elastomer actuator

When subjected to voltage,the dielectric elastomer membrane reduces its thickness and expands its area under the resulting compressive force.This characteristic enables the dielectric elastomer actuators of different structures to be designed and fabricated.By employing the thermodynamic theory and research method proposed by Suo et al.,an equilibrium equation of folded dielectric elastomer actuator with two generalized coordinates is established.The governing equations of failure models involving electromechanical instability,zero electric field,electrical breakdown,loss of tension,and rupture by stretch are also derived.The allowable areas of folded dielectric elastomer actuators are described.These results could provide a powerful guidance to the design and performance evaluation of the dielectric elastomer actuators.