Smooth Operation Changeover Scheme for Dual Stage BES-SPVA Grid Coupled System

In this paper, a linearized mixed finite volume element (MFVE) scheme is proposed to solve the nonlinear time fractional fourth-order reaction–diffusion models with the Riemann–Liouville time fractional derivative. By introducing an auxiliary variable σ=Δu, the original fourth-order model is reformulated into a lower-order coupled system. The first-order time derivative and the time fractional derivative are discretized by using the BDF2 formula and the weighted and shifted Grünwald difference (WSGD) formula, respectively. Then, a fully discrete MFVE scheme is constructed by using the primal and dual grids. The existence and uniqueness of a solution for the MFVE scheme are proven based on the matrix theories. The scheme’s unconditional stability is rigorously derived by using the Gronwall inequality in detail. Moreover, the optimal error estimates for u in the discrete L∞(L2(Ω)) and L2(H1(Ω)) norms and for σ in the discrete L2(L2(Ω)) norm are obtained. Finally, three numerical examples are given to confirm its feasibility and effectiveness.

This paper presents the design of a digital dual stage servo and the analysis of its robust stability and performance. The dual stage actuator system consists of a coarse actuator and a fine actuator. The design consists of two steps: 1) the coarse actuator loop is designed for basic performance and stability; and 2) the fine actuator loop is designed by loop shaping for superior performance of the overall system. Appropriate contribution of each actuator to the final output is adjusted differently in different frequency range. An important consideration in the second stage is to ensure that the phase difference is within /spl plusmn/120 degrees between the coarse and fine actuator paths when the magnitudes of the two are close to each other. Robustness is studied by the /spl mu/-analysis after the closed loop system is augmented by various weightings. Simulation and experimental results justify the proposed design.

Dual stage hydrogen compressor with high pressure compression ability can operate efficiently using geothermal, low temperature solar, waste energy as well as combination of these energy sources. In this study, a dual stage thermal compressor system for hydrogen compression was investigated using three different hydrogen storage materials: LaNi5, Ca0.6Mm0.4Ni5 and Ca0.2Mm0.8Ni5. Compression ratio of Ca0.2Mm0.8Ni5 was found to be 56% and 14.7% higher than those of LaNi5 and Ca0.6Mm0.4Ni5 respectively, for single stage thermal compressor system with inlet supply pressure of 600 psig. On the other hand, compression performance of Ca0.2Mm0.8Ni5 was similar to that of LaNi5 at low supply pressure (e.g. 200 psig) condition. In this paper, a dual stage hydrogen compressor system with LaNi5 in first stage and Ca0.2Mm0.8Ni5 in second stage is proposed for high pressure hydrogen compression based on the experimental results of single stage system. Results show that 53% higher compression ratio can be attained using dual stage hydrogen compressor when appropriate storage materials are selected for two stages.

A dual stage feed drive system is well suited to satisfying current demands of high performance machining with tight position control under high feed rates in the presence of disturbances. It does this by integrating an actuator with high position resolution and fast response together with a conventional linear drive. A magnetostrictive actuator (MA) with a bandwidth in the kHz range capable of several kN of force output is an ideal candidate for use as the fine positioning element in such a dual stage system. However, MAs display significant hysteresis in their performance. This makes the effective implementation of real-time fast servo control challenging. In this paper, a dynamic Preisach model is utilized to reduce the undesired nonlinearity. A sliding mode controller (SMC) is designed to deal with uncertainties such as the Preisach modeling error as well as external disturbances so as to ensure a robust stable system. Experimental results show the servo performance improvement during a feed step test for single axis control and a single axis component of a sharp path interpolation test.

With the rapid development of aero-engine manufacturing technology, the dual-rotor system has been employed in part of turbofan engine in order to improve the working performance of aircraft more efficiently. In this study, taking the counter-rotation dual-rotor as the research object, the dynamic model of dual rotor-casing coupling system is established by the aid of MATLAB. The dynamic frequency curves are in good agreement with the results in references and calculated by FEM method, that shows the validity and feasibility of the model. The local rub-impact dynamic model of dual rotor-casing coupling system is established, and rubbing analysis is carried out using Newmark- β method. The effects of rotating speed and speed ratio on local rub-impact response are deeply discussed. The results show that with the increase of rotating speed, combined frequencies and frequency multiplication components are more significant. In addition, speed ratio has a great influence on the periodic motion of the system. With the increase of the absolute value of the speed ratio, the whirl radius of the outer rotor and the normal rubbing force increase dramatically.

<div class="htmlview paragraph">The 1997 Ford Explorer introduces a new two valve single overhead cam (SOHC) version of the 4.0L V6 engine. Maximum power output is increased to 153 KW net (205 HP) at 5000 rpm and 340 N-M of torque (250 lb-ft) at 3000 rpm, which represents a 28% increase in power and an 11% increase in torque over the existing 4.0L overhead valve (OHV) design. The new design's performance features are single overhead camshafts driven by a patented “Offset Y-drive” dual stage chain system, a plastic variable induction system, and aluminum cylinder heads. For quieter and smoother operation, a main bearing ladder frame and a unique second-order balance shaft (4x4 only) are added.</div>

A dual stage PRO process has been proposed for power generation from a salinity gradient across a semi-permeable membrane. Both closed-loop and open-loop dual stage PRO system were evaluated using 2 M NaCl and Dead Sea as draw solutions, whereas the feed solution was either fresh water or seawater. The impact of feed salinity gradient resource and feed pressure on the net power generation and water flux were evaluated. The results showed that power density in stage one reached a maximum amount at, but the maximum net power generation occurred at. This result was mainly attributed to the variation of net driving pressure in stage one and two of the PRO process. The dual stage PRO process was found to perform better at high osmotic pressure gradient across the PRO membrane, for example when Dead Sea brine or highly concentrated NaCl was the draw solution. Total power generation in the dual stage PRO process was up to 40% higher than that in the conventional PRO process. This outcome was achieved through harvesting the rest of the energy remaining in the diluted draw solution. Therefore, a dual stage PRO process has the potential of maximizing power generation from a salinity gradient resource by 20%. DSPRO can be combined with desalination plant using seawater brine as the draw solution either in closed-loop or open-loop. This hybridization has multiple applications such as reducing the impact of discharging concentrated brine to sea, energy storage, and increase the recovery rate of the desalination. Power generation by DSPRO will reduce the energy consumption by the desalination processes. Waste heat from power plants can be used for the regeneration of the draw solution in the closed-loop DSPRO. Process modelling has been performed and shown promising results for DSPRO application for power generation. The impact of module configuration, area and length, with relation to draw solution concentration have shown to have significant impact on osmotically driven processes and should be counted for.

Enhanced anti-windup (AW) schemes are designed for the dual stage hard disk drive (HDD) system to solve the amplitude saturation problem of the secondary actuator. The sensitivity decoupling approach is used for designing the nominal linear controllers for the dual stage HDD systems. The AW compensators for the system are synthesized by solving a linear matrix inequality optimization. The AW scheme is further enhanced with a filter, which can be designed by the robust control methodologies. The proposed schemes and an existing AW scheme are evaluated and compared by simulation on a dual stage HDD benchmark control problem with white noise vibration disturbance.

The development of a three-dimensional coalbed-methane (CBM) numerical reservoir simulator is presented for modeling flow mechanism of coalbed methane gas reservoir and predicting its production performance. This model is a diphase (gas-water) mathematical model of applying dual grid system, and three processes, i.e. desorption, diffusion and percolation flow, undergone by coalbed methane from the coal matrix surface into wellbore are considered in the simulator. On the basis of the real gas law, Darcy's law and continuity equation, a mathematical model was established and numerically solved by use of differential discrete method; the coefficient term and production term in the equation were explicitly dealt with; and the implicit format treatment and solution were adopted to acquire the parameters and the amount of mass exchange of the coal matrix-cleat system. In addition, the program source code was written; through analyzing and contrasting examples, the simulator proved efficient and reliable in modeling the behavior of coalbed methane reservoir. The new model we have developed also permits to precisely describe the phenomena occurring within the coal cleats and micropores, and to be better understanding the production mechanisms of coalbed reservoir.

This paper describes a dual battery EV charging system with variable battery voltage operations. A wide range of EVs is now available based upon their operational flexibility and power availability. However, frequent modification in charging architecture and related components based upon the battery voltage diverseness can't be assured. To fulfill the charging requirements for multiple low power EVs, a dual battery charging system with minimal circuit components is described in this paper. A non-linear sliding mode control architecture with direct power control also ensures smooth operation during the bi-directional charging operation. In addition, the renewable and battery energy storage support is also depicted in the charging architecture to make it self-sufficient to operate in standalone mode. The control configuration is designed with MATLAB and the Simulink platform to validate the bi-directional charging operation with a Level-I charging prototype.

Dynamic characteristics investigation of a dual rotor-casing system considering the comprehensive stiffness of the intermediate bearing

To match the specific charging profile of lithium-ion batteries, inductive power transfer (IPT) systems must perform two charging modes, constant current (CC) mode and constant voltage (CV) mode. Meanwhile, an anti-misalignment capability is also essential for IPT systems in practice. To achieve both charging modes and high misalignment tolerance, this digest proposes a dual-coupled double-sided LCC compensated topology with a clamping rectifier, which assists to convert the system output from CC mode to CV mode smoothly and automatically. The self-conversion can maintain under a high misalignment with the appropriate integrated coil structure. The experimental validations are conducted on a 1-kW prototype and show that the system performs CC mode with 11 A, then transmits to CV mode with 140 V automatically. The output can be retained at the 120 mm (40%) misalignment with a maximum efficiency of 91.08%.

<div class="htmlview paragraph">State of the art electronic restraint systems rely on the acceleration measured during a vehicle crash for deployment decisions. The acceleration signal is analyzed with different criteria, among which the velocity change is a dominant criterion in almost any existing crash detection algorithm. Sensors in the front crush zone have recently been added to help develop restraint systems that comply with the new FMVSS208 and EuroNCAP regulations. Front crash sensors are usually evaluated for their velocity change during a crash and typically play a key role in the deployment decision. CAE based FEA analysis has recently been used to generate signals at the sensor module locations in crash simulations to provide supplemental information for crash sensing algorithm development and calibration. This paper presents an initial effort in developing a velocity-based crash detection algorithm, that allows broad use of CAE generated velocity time histories for system calibration. Sample calibrations for a FMVSS 208 and EuroNCAP compatible dual stage airbag system are shown based on data obtained from testing and simulation of production vehicles. Deployment times established using the velocity-based algorithm are comparable with those determined from a traditional acceleration-based algorithm. It is further shown that CAE analysis provides acceleration data, which give the same system response as real vehicle data when evaluated with appropriate algorithms.</div>

Digital control of smart structures

Design and experimental investigation of digital model predictive current controller for single phase grid integrated photovoltaic systems