Design Of Power Transmission System Research Articles

Model for the calculation of kinematic roughness in the tooth root

For the design of power transmissions, an increase in power density is necessary. This development leads to higher requirements on the tooth root design with high load capacity. In addition to optimizing the load and stress distribution by adapting the tooth root geometry, the load capacity of the gears can be increased by optimizing the workpiece surfaces. For this reason, a model for predicting the geometric deviations due to kinematics in the tooth root and their influence on the roughness is to be developed. With this model, the ideal roughness resulting from the process kinematics of hobbing can be predicted and used for process design.

Green and Light Weight Vehicles Power Transmission System Design and Development

Green and Light Weight Vehicles Power Transmission System Design and Development

Output Characteristics of GaAs Cell Irradiated by Laser

The output characteristics of GaAs cell are keys for the laser wireless power transmission system design. The measurement platform for the output characteristics of GaAs cell is established by single-junction GaAs cell and 1064 nm fiber laser. The influence rules of laser power and temperature on the short-circuit current, open-circuit voltage, peak power, fill factor, and conversion efficiency are measured. The measurement results show that the conversion efficiency firstly increases and then decreases with an increase in laser power, and reaches a maximum of 54.5% at the laser power of 0.405 W, whereas the conversion efficiency decreases with an increase in temperature, and decreases slowly with an increase in laser power.

Novel Detection Scheme for LSAS Using Power Allocation in Multi User Scenario with LTE-A and MMB Channels

Massive MIMO (also known as the "Large-Scale Antenna System") enables a significant reduction of latency on the air interface with the use of a large excess of service-antennas over active terminals and time division duplex operation. For large-scale MIMO, several technical issues need to be addressed (e.g., pilot pattern design and low-antenna power transmission design) and theoretically addressed (e.g., channel estimation and power allocation schemes). In this paper, we analyze the ergodic spectral efficiency upper bound of a large-scale MIMO, and the key technologies including channel uplink detection. We also present new approaches for detection and power allocation. Assuming arbitrary antenna correlation and user distributions, we derive approximations of achievable rates with linear detection techniques, namely zero forcing, maximum ratio combining, minimum mean squared error (MMSE) and eigen-value decomposition power allocation (EVD-PA). While the approximations are tight in the large system limit with an infinitely large number of antennas and user terminals, they also match our simulations for realistic system dimensions. We further show that a simple EVD-PA detection scheme can achieve the same performance as MMSE with one order of magnitude fewer antennas in both uncorrelated and correlated fading channels. Our simulation results show that our proposal is a better detection scheme than the conventional scheme for LSAS. Also, we used two channel environment channels for further analysis of our algorithm: the Long Term Evolution Advanced channel and the Millimeter wave Mobile Broadband channel.

Algorithm to solve a chance‐constrained network capacity design problem with stochastic demands and finite support

AbstractWe consider the problem of determining the capacity to assign to each arc in a given network, subject to uncertainty in the supply and/or demand of each node. This design problem underlies many real‐world applications, such as the design of power transmission and telecommunications networks. We first consider the case where a set of supply/demand scenarios are provided, and we must determine the minimum‐cost set of arc capacities such that a feasible flow exists for each scenario. We briefly review existing theoretical approaches to solving this problem and explore implementation strategies to reduce run times. With this as a foundation, our primary focus is on a chance‐constrained version of the problem in which α% of the scenarios must be feasible under the chosen capacity, where α is a user‐defined parameter and the specific scenarios to be satisfied are not predetermined. We describe an algorithm which utilizes a separation routine for identifying violated cut‐sets which can solve the problem to optimality, and we present computational results. We also present a novel greedy algorithm, our primary contribution, which can be used to solve for a high quality heuristic solution. We present computational analysis to evaluate the performance of our proposed approaches. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 236–246, 2016

Windage Power Losses of Ordinary Gears: Different CFD Approaches Aimed to the Reduction of the Computational Effort

Efficiency improvement is one of the main challenges in all fields of design. The reduction of power losses is becoming a great concern also in the design of power transmissions. For this reason it is important to have specific models available in order to quantify the power losses during the design stage. The power losses of a gear transmission can be subdivided into bearing losses, seal losses, meshing losses and hydraulic losses. Although literature provides models for the prediction of losses related to bearings or to gear meshing, for the calculations of the losses generated by the interaction with the lubricant, only few and simplified models are available. For this reason the authors recognize that a general purpose method is required in order to overcome this lack of fit and to improve the capability to predict the efficiency of gearboxes. Being able to compare different design solutions means being able to improve the efficiency, reduce the operating temperature and, consequently, improve the reliability of the system. In this paper, the windage losses generated by a single rotating gear have been studied exploiting different numerical approaches. The results obtained have been compared with measurements showing good agreement.

Attenuation and deformation characteristics of lightning impulse corona traveling along bundled transmission lines

Comprehensive study of the impulse corona characteristics is helpful to understand the transient process and guarantee a suitable insulation design of power transmission systems. In this paper, first the attenuation and deformation characteristics of lightning overvoltage traveling along a 500kV experimental transmission line are tested. Then the lightning impulse corona characteristics on different bundled conductors commonly used in the 110–1000kV power transmission lines are experimentally investigated, the impulse corona Q–V data measured in the corona cage is transformed into those on the corresponding overhead lines. The influence of bundle geometry on corona is analyzed. Attenuation and deformation effects of lightning impulse corona along transmission lines are evaluated by comparing the simulation and test results. Simulation shows the amplitude and wave-front steepness attenuate remarkably, and the deformation of the voltage mainly happens when the impulse voltage exceeds the corona inception one.

A CFD analysis of the oil squeezing power losses of a gear pair

Effi ciency is becoming more and more a main concern in the design of power transmissions and the demand for high effi ciency gearboxes is continuously increasing. Also the more and more restrictive euro standards for the reduction of pollutant emissions from light vehicles impose to improve the effi ciency of the engines but also of the gear transmissions. For this reason the resources dedicated to this goal are continuously increasing. The fi rst step to improve effi ciency is to have appropriate models to compare different design solutions. Even if the effi ciency of transmissions is quit high if compared with the effi ciency of the engines and appropriate models to predict the power losses due to gear meshing, to bearings and to seals already exist, in order to have a further improvement, some aspects like the power losses related to the oil churning, oil squeezing and windage are still to be investigated. In previous papers the authors have investigated by means of computational fl uid dynamic (CFD) analysis and experimental measurements the churning losses of planetary speed reducers (in which there is a relative motion between the “planets + planet carrier” and the lubricant). Also the windage power losses have been studied by the authors in previous papers. This report is focused on the oil squeezing power losses. This kind of losses is associated with the compressionexpansion process by the meshing teeth. The contraction of the volume at the gear mesh implies an overpressure that induces a fl uid fl ow primarily in the axial direction and this, for viscous fl uids, means additional power losses and a decrease of the effi ciency. In this work this phenomena has been studied by means of some CFD simulations. The infl uence of some operating conditions like the lubricant properties, the rotational speed and the temperature has been studied.

Study on the Influence of the DC Voltage on the Upward Leader Emerging From a Transmission Line

The evaluation of the lightning shielding failure of a transmission line is very important in power transmission system design, and the operation voltage has rarely been considered before. However, when the operation voltage reaches 800 kV and the tower height is near 100 m, the influence of operation voltage may not be ignored. In this paper, an experimental system consisting of an air gap between a plate/rod and a conductor was established, where the dc voltage could be applied to the conductor and was accompanied by a negative impulse voltage on the plate/rod electrode. An upward leader up to 1.54 m in length was observed, and the leader velocity and charge density were obtained in a 11-m-long air gap, whereas the voltage on the conductor was 800-kV dc. The influence of dc operation voltages on the upward leader was studied. The experimental results showed that the upward leader will emerge much earlier and may progress longer with dc operation voltages. That is, the lightning attachment to the conductor may occur more easily when the voltage of the conductor is opposite in polarity to that of the downward lightning than when the conductor has no operation voltage.

Hydraulic losses of a gearbox: CFD analysis and experiments

Efficiency is becoming a main concern in the design of power transmissions. It is therefore important, especially during the design phase, to have appropriate models to predict the power losses. For this reason CFD (computational fluid dynamics) simulations were performed in order to understand the influence of geometrical and operating parameters on the losses in power transmissions. The results of the model were validated with experimental results.

Optimum behavior: Wireless power transmission system design through behavioral models and efficient synthesis techniques

In this article, the different challenges and open issues regarding WPT systems have been presented considering both the transmitting and receiving ends. The challenges in the receiving side include the accurate modeling of the rectifying elements, the adequate selection of the rectifier topology, and the joint optimization of antenna and rectifier circuit. The challenges in the transmitting side are mainly in the improvement of the dc-to-RF conversion efficiency and in the selection of the optimum transmitted signal waveform. The final goal of most of these challenges is to take advantage of the nonlinear nature of the rectifying elements in order to maximize the RF-to-dc conversion efficiency in the receiving end of WPT systems.

Contact finite element method for dynamic meshing characteristics analysis of continuous engaged gear drives

The dynamic meshing characteristics of gear drives have been a major concern in the design of power transmission systems as they affect vibration, acoustic noise, durability and efficiency. Gaining a more comprehensive understanding of the dynamic meshing characteristics of continuous engaged gear drives is a key to the development of power transmission systems. In this paper, a dynamic contact finite element analysis method, considering the variation of the engaged teeth pairs, the loaded elastic and contact deformations, and the sliding friction, is presented for the dynamic meshing characteristics analysis of continuous and elastic engaged gear drives. Various kinds of continuous engaged gear models under low and high speed condition are simulated and compared using the presented method. The tooth profile modification was designed based on the simulation results. Moreover, the effects of the tooth profile modification, the sliding friction and the time-varying meshing stiffness upon the dynamic meshing characteristics of continuous engaged gear drives are discussed in detail. The results show that the method is not only effective in designing and evaluating the tooth profile modification, but also in studying the dynamic meshing characteristics of continuous engaged gear drives with realistic time-varying meshing stiffness and tooth sliding friction. The present method could provide an effective tool for vibration mechanism study and dynamic design of the continuous engaged gear drives considering more influence factors.

CFD Simulations of Splash Losses of a Gearbox

Efficiency is becoming a main concern in the design of power transmissions. It is therefore important, especially during the design phase, to have appropriate models to predict the power losses. For this reason, CFD (computational fluid dynamics) simulations were performed in order to understand the influence of geometrical and operating parameters on the losses in power transmissions. The results of the model were validated with experimental results.

The Design of Power Transmission of Electric Screw Press Directly Driven by Permanent Magnet Disc Synchronous Motor

Screw press is a significant forging equipment, its most important advantage is exact energy control which ensures high process reliability and repeatability, furthermore, using low speed large torque motor directly driving the press can remove the clutch, gear, belt, et al driving device, so that the power consumption could be reduced effectively. In this paper, a novel electric screw press directly driven by permanent magnet disc synchronous motor is presented, Referring to the technical parameters from the J58K electric screw press, the method which calculates the structure and electromagnetic parameters of the power transmission is introduced.

Minimum power transmission design for cognitive radio networks in non-stationary environment

In this paper, we develop an approach to allow the cognitive radio to operate in the presence of the licensed user using bio-inspired method called particle swarm optimization. This method is invoked to solve the constrained nonlinear optimization problem for the minimum power transmission and minimum bit error rate in order to reach to maximum capacity. In addition, the received interferences at primary users remain below a specific threshold level as well as the secondary users are guaranteed with their quality of service. We reveal the modulation index in the optimization procedure. A numerical study is performed to show the convergence behavior of the proposed bio-inspired algorithm in a non-stationary environment with a dynamic cost function.

Modelling approach for the simulation-based preliminary design of power transmissions

The promises of Model-Based Design have led to the development of numerous methodologies and software tools, especially for the specific or detailed design stages , from controller design to finite element analysis . However, the Model-Based Design of actuation systems lacks methodologies and expressive simulation models that are suited to preliminary design, where key technical decisions are taken considering various design alternatives and few available design details. In order to fill this gap, the present paper illustrates how scaling laws and acausal modelling can be used as a design tool, exploiting inverse simulation capabilities to evaluate technological alternatives quantitatively from limited design detail information. The application of the modelling approach is shown for two major components of mechanical transmission systems: roller bearings and ball and roller screws. The scaling laws presented are validated with manufacturers’ data. To conclude, the suitability of the proposed methodology is illustrated with the preliminary sizing of an electromechanical actuator for an aircraft primary flight control surface (aileron).

Mode I stress intensity factors for curved cracks in gears by a weight functions method

The most recent trend in power transmission design considers the damage‐tolerant approach as one of the methods to obtain safe, reliable and light systems. This means that components containing cracks must be considered and analysed to understand the conditions that cause critical cracks and defects and their dimensions.In this paper a cracked tooth of an automotive gearwheel is considered. A numerical procedure (based on the slice synthesis weight function method) to calculate the stress intensity factors of curved cracks due to bending loads is illustrated. The results are compared with those obtained by expensive finite element calculations. The agreement is satisfactory and the proposed technique proves to be very attractive from the point of view of time saving.One example of an application to fatigue design practice is provided, namely the analysis of fatigue crack propagation in surface‐treated gears. The results show the role played by residual stresses induced by carburizing and shot peening.

Evolutionary optimization within an intelligent hybrid system for design integration

An intelligent hybrid approach has been developed to integrate various stages in total design, including formulation of product design specifications, conceptual design, detail design, and manufacture. The integration is achieved by blending multiple artificial intelligence (AI) techniques and CAD/CAE/CAM into a single environment. It has been applied into power transmission system design. In addition to knowledge-based systems and artificial neural networks, another AI technique, genetic algorithms (GAs), are involved in the approach. The GA is used to conduct optimization tasks: (1) searching the best combination of design parameters to obtain optimum design of gears, and (2) optimization of the architecture of the artificial neural networks used in the hybrid system. In this paper, after a brief overview of the intelligent hybrid system, the GA applications are described in detail.

Design Automation with the Aids of Multiple Artificial Intelligence Techniques

In most cases, to design a product through the process of total design is a tedious task. In order to speed up the process and hence to reduce time to market, an intelligent integrated system (IIS) approach has been developed to integrate various stages in total de sign process, including conceptual design, detail design and manufacture. The integration is achieved by blending multiple artificial intelli gent (AI) techniques and CAD/CAE/CAM packages into a single environment. The Al techniques utilised in the approach include knowledge-based systems, artificial neural networks and genetic algorithms. The IIS has been applied in mechanical power transmission system design, which approves that the approach is a powerful tool for design automation. Wthin the IIS environment, the multiple Al tech niques coexist and complement each other, and thus their drawbacks are eliminated and their advantages are maximised.

Expert system for selecting speed reduction components for a power transmission

Abstract This paper describes the development of an expert system that will allow for the concurrent consideration and analysis of the many facets of product constraints, particularly function and manufacturability, at the early stages of power transmission development. The Power Transmission Design Assistant methodology is based on the concept of directed refinement, where the product and analysis methodology become less abstract as more information is given. This allows for analysis and guidance throughout the product development process. The methodology has been demonstrated on a small-scale, semi-automatic tool. The tool was the foundation for a larger tool that incorporates expert rules to help optimize power transmission component design.