Number Of Operating Modes Research Articles

COMBINED POWER PLANT OF A MOTOR VEHICLE

Currently, the most promising areas of development of motor transport are an increase of the horsepower characteristic of their power plants as well as increase of fuel efficiency, and reduction of the toxicity level of exhaust fumes. An internal combustion engine as a power unit of the car in a number of operation modes (supplemental motion, small work load, idling, etc.) works extremely inefficiently and contains the high concentration of harmful components in the exhaust fumes. Additionally, in a context of growing shortage of carbohydrate fuels and increase in their value, the problem of the fuel-burn improvement is especially acute. To improve the environmental compatibility and efficiency of power plants of the vehicles, combined cycle power plants are used. One of the most important problems that the machine construction faces is the creation of environmentally friendly and economical power plants. A hybrid power plant, which contains several power units operating on different physical principles, is proposed by the authors. The main power unit uses the energy of liquid or gaseous fuel in the mode of an internal combustion engine; the auxiliary power unit which is made as a reverse volumetrical driving machine with swinging motion of the work tools (forcers or blades), uses air power which comes from a pneumocylinder through a cooler and / or pneumatic air tank. The auxiliary power unit is equipped with a reversible invertor of the driving direction, made on the basis of a spherical slider-crank mechanism. This insures the operation of the auxiliary power unit in the mode of a pneumatic motor or compressor in accordance with the algorithm generated by the electronic control unit of the combined power plant of the vehicle. To utilize the heat energy of the exhaust fumes of the main power unit, the combined power plant is additionally equipped with a Stirling engine or steam generation module and a steam engine; in order to break energy recuperation of the vehicle it is additionally equipped with a hydraulic or electrodrive. Naturally, when choosing the specific forms of application of combined cycle power plants, any combinations of auxiliary power units are possible. They can be supplemented and / or specified based on the knowledge of specialists. Combined cycle power plants are technically complete solution. Their industrial applicability is obvious and is substantiated by experiments. Nowadays, the creation of a combined cycle power plants of a vehicle, which are a combination of several engines operating on different physical principles is the task of great economic importance. Combined power plants this allows to reduce fuel consumption per 100 km significantly, increase energy potential, horsepower characteristic and improve the environmental performance of the vehicle. The work is planned to be continued in the direction of optimization synthesis of auxiliary power units that work on different physical principles.

Classification of a 3-RER Parallel Manipulator Based on the Type and Number of Operation Modes

Abstract The type/number of operation modes of a parallel manipulator (PM) may vary with the link parameters of the PM. This paper presents a systematic classification of a 3-RER PM based on the type/number of operation modes. Here, R and E denote revolute joint and planar joint, respectively. The 3-RER PM was proposed as a 4-degree-of-freedom (DOF) 3T1R PM in the literature. Using the proposed method, classification of a PM based on the type/number of operation modes can be carried out in four steps, including formulation of constraint equations of the PM, preliminary classification of the PM using Gröbner cover, operation mode analysis of all the types of PMs using primary decomposition of ideals, and identification of redundant types of PMs. The classification of the 3-RER PM shows that it has 13 types. Besides the two 4-DOF 3T1R operation modes, different types of 3-RER PMs may have up to two more 3-DOF or other types of 4-DOF operation modes. Motion characteristics of the moving platform of 3-RER PMs are also identified using Euler parameter quaternions. This work is the first systematic study on the impact of link parameters on the operation modes of the 3-RER PM and provides a solid foundation for further research on the design and control of 3-RER PMs and other multi-mode (or reconfigurable) PMs.

Reconfigurable Frequency Selective Rasorber Covering Extremely Wide Transmission Frequency Range

Rasorbers with reconfigurable transmission frequency are of great interest over the past few years. However, existing devices exhibit a limited number of operation modes and cover a narrow transmission frequency range, making them unacceptable for wideband applications. In this work, a high-performance reconfigurable rasorber with mechanically-controlled frequency selective surface (FSS) and an electronically-tuned resistive layer is proposed. Theoretical analysis based on transmission line theory and numerical simulations is performed to investigate the performance of the proposed device. The rasorber were fabricated and free-space measurements were also carried out to validate the simulation results. The device can operate between single-, dual- and triple-passband modes by mechanically tuning the FSS under a fixed external bias voltage. Under single-passband mode, the transmission frequency can also be tuned continuously through simultaneously controlling the mechanically-tunable FSS and electronically-tunable resistive layer. A minimum insertion loss as low as 0.16 dB at 4.03 GHz is achieved from the measurement results. The maximum measured fractional absorption bandwidth is 87.9%, comparable to the state-of-art maximum absorption bandwidth of existing reconfigurable rasorber. The measured overall fractional transmission frequency range under normal incidence wave is 63.9%, far beyond that of any other existing reconfigurable counterparts.

Robust Deadlock Avoidance for Sequential Resource Allocation Systems With Resource Outages

While the supervisory control (SC) problem of (maximally permissive) deadlock avoidance for sequential resource allocation systems (RASs) has been extensively studied in the literature, the corresponding results that are able to address potential resource outages are quite limited, both, in terms of their volume and their control capability. This paper leverages the recently developed SC theory for switched discrete event systems (s-DES) in order to provide a novel systematic treatment of this more complicated version of the RAS deadlock avoidance problem. Following the modeling paradigm of s-DES, both the operation of the considered RAS and the corresponding maximally permissive SC policy are decomposed over a number of operational modes that are defined by the running sets of the failing resources. In particular, the target supervisor must be decomposed to a set of “localized predicates,” where each predicate is associated with one of the operational modes. A significant part, and a primary contribution, of this paper concerns the development of these localized predicates that will enable the formal characterization and the effective computation of the sought supervisor. With these predicates available, a distributed representation for the sought supervisor that is appropriate for real-time implementation is eventually obtained through an adaptation of the relevant distributed algorithm that is provided by the current s-DES SC theory. Note to Practitioners —This paper extends the existing theory of deadlock avoidance for buffer-space allocation in flexibly automated production systems so that it accounts for disruptive effects due to potential temporary outages of some of the system servers. The set of the failing servers at any time instant defines the corresponding operational mode for the underlying resource allocation system. The primary problem that is addressed by this paper is the synthesis of a resource allocation policy that will ensure the ability of all process instances that do not require the failing resources in a particular mode, to execute repetitively and complete successfully while the system remains in that mode. In line with some past literature on this problem, we call the corresponding supervisory control problem as “robust deadlock avoidance,” and we leverage results from the recently emerged theory for modeling and control of switched discrete event systems in order to characterize and compute a maximally permissive solution for it.

A Highly Efficient and Reliable Power Scheme Using Improved Push-Pull Forward Converter for Heavy-Duty Train Applications

Electronically controlled pneumatic (ECP) brake systems have become popular in heavy-duty train applications because of their advantages, which include shorter stopping distances, improved handling, and less brake-shoe and wheel wear. In ECP brake systems, an improved power supply is required to support efficient and reliable operations. In this paper, we propose a new power converter for ECP brake systems, which is derived from a conventional push-pull converter. As opposed to conventional push-pull converters, we insert a clamping capacitor into the proposed circuit. This clamping capacitor simultaneously enables a greater number of operation modes for the proposed converter and absorbs the voltage spikes in the switch. The proposed converter is more suited for ECP brake applications that require high power, low voltage ripple, and high impedance. We theoretically analyze the proposed converter, and present the design guidelines. Further, we discuss the modeling and control aspects. We demonstrate the operations of the proposed model by performing both simulations and experiments.

Governor stability simulations of Svartisen power plant verified by the installed monitoring system on site

Many Norwegian hydro power plants have complex lay-out with several reservoirs, broke intakes, surge shafts and even air cushion chambers. There are kilometers of excavated tunnels as well as long tail water systems. The stations are often equipped by multiple of turbines, both in series and parallel. A number of operation modes are therefore possible. Doing transient simulations and simulations of governor stability in the design phase, the problem is to find the worst case scenario regarding these operating modes. Svartisen power plant has been of particular interest these days. The power plant is originally designed for two 350 MW Francis turbines, however, only one turbine was installed. When designed, governor stability was regarded as problematic due to the long penstock. A long penstock will give a too high time constant for the hydraulic inertia. The main problem here is, however, the water hammer frequency that interferes with the governor performance. The frequency is in the same range as the cross frequency. Therefore the governor will react on these water hammer waves, which in its nature is notoriously unstable. The common solution is to build an air cushion and thereby increase the water hammer frequency above the cross frequency. The expenses were, however, deemed too high, and it was necessary to seek for other solutions. A pressure feedback on the governor was introduced in order to have stable operation at least for two turbines. With only one turbine installed, the pressure feedback has not been activated because, based on the simulations, it was regarded unnecessary. Even if the original simulations shows good stability margins when only one turbine is running, there has been some indications that the aggregate has suffered from instability. In 2004 Svartisen Power Plant was equipped with a comprehensive monitoring system. Both the turbine and the generator performance have been observed. This gives valuable information on how the hydropower plant has performed during start ups, close downs and steady state operation. The data has for instance been used to verify the simulations of governor stability of the excising turbine.This will also secure the simulations done with an additional turbine installed.

Effects of Shared Secondary Controls and Operational Modes on Performance and Perceived Workload during a Simulated Driving Task

During a simulated driving task, subjects were prompted to actuate specific shared (mode-based) secondary controls, which required subjects to ensure that the proper mode was active before actuating the control. The independent variables were number of controls, number of operational modes, and number of functions assigned to a control. The dependent variables included performance time, speed and lane deviations, error measures, and subjective ratings. Subjects perceived higher workloads and took longer to complete the secondary task as the number of controls and number of functions increased. The number of operational modes had no effect on secondary control performance while subjective ratings indicated little or no significant differences between multiple and single mode systems. Comparing systems with identical number of functions, a system that reduces the number of controls by assigning a set of functions (in which each function belongs to a different mode) to each control may be preferable to a system that dedicates each function to a single control.

Optimal Reactive Power Planning, Part I—Load Level Decomposition

This paper presents an efficient algorithm for the reactive power planning of transmission networks in normal operations. In order to obtain optimal investment planning an optimal operation is essential. The objective function of an optimal operation is the fuel cost of the generators. The investment variables are the shunt reactors and the capacitors at selected buses. The operation problem contains every physical constraint such as voltage limits, generators' capacities and Var compensators' capacities. The number of operation modes is so large because of the various load levels in a year. So the variables are increased tremendously, in proportion to the load levels and the investment variables. This leads to difficult computation and to a storage limit. To overcome these difficulties a new variable decomposition technique is adopted which can seperate the operation and the investment variables. This technique makes it possible to decompose load levels and to solve optimal operation problems independently in each level. Therfore the only problem remaining to be solved is the investment problem. The modified investment problem includes implicitly the operation and the operation problem needs no longer to be computed. The quasi linearization method is applied to each problem and so computing time is reduced in a great deal.