LUMPED-PARAMETER MODEL OF MASS TRANSFER IN HEMODIALYZER WITH ULTRAFILTRATION

1 INTRODUCTIONHemodialysis with ultrafiltration,also called hemodiafiltration(HDF),is a main methodof treatment for patients with chronic renal failure.The HDF procedure providesadequate removals of both small and middle molecular weight toxic substamces fromuremic blood,which is not possible by dialysis or ultrafiltration alone.According toclinical experience[1],the HDF procedure is well accepied by the patients,and thetreatment time is reduced by using it.

Lumped-Parameter Thermal Network Model and Experimental Research of Interior PMSM for Electric Vehicle

A 25kW interior permanent magnet synchronous machine(IPMSM)applied to the electric vehicle is introduced in the paper.A lumped-parameter thermal network model is presented for IPMSM temperature rise calculation.Furthermore,a 3D liquid-solid coupling model considering the assembly clearance is compared with the 2D lumped-parameter thermal network model.Finally,a dynamometer platform for temperature rise measurement is established to verify the above-mentioned methods,which obtains the measured efficiency map at rated load case and overload case.At the same time,the measured no-load back electromotive Force(EMF),load line input voltage and load current are gathered.Thermocouple PTC100 is used to measure the temperature of the stator winding and iron core,and the FLUKE infrared thermal imager is applied to measure the surface temperature of PMSM and controller.Testing result shows that the lumped-parameter thermal network have a high accuracy to predict each part temperature.

Multi-physics analysis of permanent magnet tubular linear motors under severe volumetric and thermal constraints

Permanent magnet tubular linear motors(TLMs) arranged in multiple rows and multiple columns used for a radiotherapy machine were studied. Due to severe volumetric and thermal constraints, the TLMs were at high risk of overheating. To predict the performance of the TLMs accurately, a multi-physics analysis approach was proposed. Specifically, it considered the coupling effects amongst the electromagnetic and the thermal models of the TLMs, as well as the fluid model of the surrounding air. To reduce computation cost, both the electromagnetic and the thermal models were based on lumped-parameter methods. Only a minimum set of numerical computation(computational fluid dynamics, CFD) was performed to model the complex fluid behavior. With the proposed approach, both steady state and transient state temperature distributions, thermal rating and permissible load can be predicted. The validity of this approach is verified through the experiment.

Thermal analysis of surface-mounted permanent magnet synchronous motor for electric vehicle application

As a driving motor, surface mounted permanent magnet synchronous motor exhibits high efficiency and high power density. However, it is susceptible to suffer irreversible demagnetization and insulation failure of coils under severe thermal load condition. Therefore, it is essential to predict temperattrre distribution in the driving motor. In this paper, a lumped parameter thermal mode/of surface mounted permanent magnet is investigated. By using finite element method, the iron loss distribution in various parts of the driving motor is achieved. Moreover, the influences of interface gap and flow rate on temperature distribution are discussed. Finally, the simulation of temperature distribution in different parts of the driving motor is achieved. The presented methodology contributes to verify the feasibility of the driving motor design.

Protection Distance of Surge Protective Devices in Low Voltage Distribution Systems

Protection distance of surge protective devices (SPDs) is an important problem in designing a good location scheme of SPDs in low voltage distribution systems for protecting electrical equipments against over- voltage caused by lightning stroke. The simplified lumped-parameter circuit model and the circuit method were used to study the protection distance problem of SPDs. The analytical solutions of the load voltage and general equations of the protection distance of SPDs under different load conditions were given. Simulation results of examples proved the validity of the proposed analytical method.

A dynamic-model-based fault diagnosis method for a wind turbine planetary gearbox using a deep learning network

The planetary gearbox is a critical part of wind turbines,and has great significance for their safety and reliability.Intelligent fault diagnosis methods for these gearboxes have made some achievements based on the availability of large quantities of labeled data.However,the data collected from the diagnosed devices are always unlabeled,and the acquisition of fault data from real gearboxes is time-consuming and laborious.As some gearbox faults can be conveniently simulated by a relatively precise dynamic model,the data from dynamic simulation containing some features are related to those from the actual machines.As a potential tool,transfer learning adapts a network trained in a source domain to its application in a target domain.Therefore,a novel fault diagnosis method combining transfer learning with dynamic model is proposed to identify the health conditions of planetary gearboxes.In the method,a modified lumped-parameter dynamic model of a planetary gear train is established to simulate the resultant vibration signal,while an optimized deep transfer learning network based on a one-dimensional convolutional neural network is built to extract domain-invariant features from different domains to achieve fault classification.Various groups of transfer diagnosis experiments of planetary gearboxes are carried out,and the experimental results demonstrate the effectiveness and the reliability of both the dynamic model and the proposed method.

Nonlinear dynamical analysis of some microelectromechanical resonators with internal damping

In this paper, a new Kelvin-Voigt type beam model of a microelectromechanical resonator made of power-law materials taking into account internal strain-rate damping is proposed and the corresponding lumped-parameter model is derived. Analytical formulas of the lumped parameters in the model are presented. And the pull-in solution is analyzed based on the lumped-parameter model. It is demonstrated analytically and numerically that the internal damping plays an important role in the pull-in solution as well as in determination of the amplitudes and frequencies of the resonator. The hysteresis loops are provided for this model with initial conditions using numerical simulations. The approximation of the electrostatic force in the lumped-parameter model can describe the relations between amplitudes and frequencies with different values of the stiffness and damping coefficients quite well.

Novel Mechanical Interface Design for Automotive Starting Systems

Stop-start vehicles(SSVs)represent a potential alternative for improving internal combustion engine(ICE)efficiency.SSVs provide ICEs with the functionality of turning the engine off during traffic halts and restarting it without intervention by the driver.This strategy reduces fuel consumption,especially in dense urban traffic areas,and contributes to emissions reduction to meet green emissions targets.The most widely adopted SSV system has a mechanical interface to connect the electric starter motor to the ICE,which requires increased robustness compared with standard starting motors.This requirement allows the motor to withstand a higher number of engine start cycles compared with a standard starting motor.Nevertheless,it is a critical problem for wider adoption of SSVs.As SSV systems usually are based on the conventional starting system,its durability and noise remains a critical issue to be addressed by automakers.The typical pinion-ring gear interface uses intermittent gear meshing to form a transient coupling interface.The research reported here presents the development of an innovative mechanical interface for starting systems,called the permanent coupling(PC)-type interface,which reduces noise and increases durability compared with the existing design.The results obtained by a functional prototype of the PC-type mechanical interface confirm the feasibility of the proposed concept.The methodology is based on a product development process integrated with lumped-parameter modeling and virtual simulation aimed at reducing failures during prototype test-ing.The new mechanical interface was proven to be a good candidate for increasing the use of SSVs in the automotive market.