Design considerations for hybrid battery/supercapactior systems for pulsed power

Design considerations for combined cooling, heating, and power systems at altitude

Product design based on discrete particle modeling of a fluidized bed granulator

Preliminary design of a complex system often involves exploring a large design space. This may require repeated use of computationally expensive simulations. To ease the computational burden, surrogate models are built to provide rapid approximations of more expensive models. However, the surrogate models themselves are often expensive to build because they are based on repeated experiments with computationally expensive simulations. An alternative approach is to replace the detailed simulations with simplified approximate simulations, thereby sacrificing accuracy for reduced computational time. Naturally, surrogate models built from these approximate simulations will also be imprecise. A strategy is needed for improving the precision of surrogate models based on approximate simulations without significantly increasing computational time. In this paper, a new approach is taken to integrate data from approximate and detailed simulations to build a surrogate model to describe the relationship between output and input parameters. Experimental results from approximate simulations form the bulk of the data, and they are used to build a model based on a Gaussian process. The fitted model is then ‘adjusted’ by incorporating small amounts of data from detailed simulations to obtain a more accurate prediction model. The effectiveness of this approach is demonstrated with a design application for a cellular material that is used to cool a microprocessor. The emphasis is on the method and not on the results per se.

The input LC resonance is a consideration in the filter design for Current Source Rectifiers (CSR). One challenge in this design is that the rectifier system can have a range of total equivalent line inductance on the CSR ac side due to the variable inductance from the power system. Furthermore, it is found in this paper that the CSR dc side circuit can also affect the input resonance. These factors may lead to an unexpected LC resonance on the CSR input side. One approach to address this issue is to increase the filter size. However, optimized design and performance cannot be guaranteed in this case. This paper investigates the input resonance of a pulse-width-modulated (PWM) CSR systematically and proposes a procedure for input filter design which can avoid the unexpected LC resonance on the CSR ac side. The proposed strategy results in a better system performance and less sensitivity to the source inductance from the power system. The designed methods are validated by the simulation and experiment results.

<p>The focus of this research is the concept of the 'Performance Sketch' tool. This is to use detailed simulation software to calculate (plausible) energy performance of designs quickly. Analogous to the Architectural Sketch the Performance Sketch uses high quality tools (detailed simulation) to create an accurate, but simple representation of the essential properties of a building, as opposed to a detailed representation. The aim of this research is to assess the consistency between the predictions produced by performance sketch design tools and the calculations produced by detailed design tools. The Lawrence Berkeley National Laboratory’s (LBNL) computer software COMFEN (COMmercial FENestration) is a performance sketch tool. It makes the power of the complex detailed design simulation package EnergyPlus available in the very early stages of the design process. It uses a single zone, single external façade EnergyPlus model to explore the costs and benefits of alternate façade designs. The hypothesis tested is that the COMFEN (single-zone) energy performance calculation method is plausible for early design analyses. It evaluates the performance sketch approach from three different points of view: first, COMFEN was introduced to various practitioners in the building industry to gather use-case feedback on the performance sketch approach. A list of specifications for performance sketch design tools was developed based on these use-cases. Second, it examines whether the optimum façade identified by COMFEN creates the optimum performance complex building when this optimum façade is incorporated into detailed building models. Finally, refinements of the nature of the performance sketch based on this use-case feedback were tested in EnergyPlus. The thesis concludes by drawing together these three threads into an outline of a practitioner-based definition of an ideal performance sketch which has been tested in practical application.</p>

In typical distribution systems, the proliferation of nonlinear loads results in deterioration of the power quality. Standards such as the IEEE-519 are imposing harmonic limits for end users and utility systems. Passive filters have been commonly applied to limit the flow of harmonic current in distribution systems. However they introduce resonance in the power system. They also tend to be bulky, particularly if the number of harmonic components to be cancelled increases. Active filters have been developed to provide better performance. Some design considerations are outlined in the paper, such as real-time emulation of tuned LC filter, selective harmonic elimination based on harmonic rotating frames, and instantaneous total harmonic cancellation. Some experimental results are included.

Energy savings continues to build momentum on a global scale. The telecommunication industry has responded with high efficiency DC power systems to reduce energy consumption. This paper explores the design considerations of high efficiency (96%) telecom rectifiers in concert with high power density requirements (34W/inch3). Specifically, the design considerations of a high efficiency, high density bridgeless PFC stage followed by a LLC DC-to-DC stage is explained. Experimental results are presented to validate the design approach.

Electromagnetic design considerations for fast acting controllers in a power system is introduced and defined. A distinction is made in relation to the more commonly understood system control design necessary for damping electromechanical oscillations using stability programs and eigenanalysis. Electromagnetic eigenanalysis tools have limited availability and are consequently rarely used. Electromagnetic transients programs (EMTP) on the other hand are widely used and a procedure for undertaking electromagnetic control design of fast acting controllers in a power system using EMTP is presented.

Transient faults are expected a be a major design consideration in future microprocessors. Recent proposals for transient fault detection in processor cores have revolved around the idea of redundant threading, which involves redundant execution of a program across multiple execution contexts. This paper presents a new approach to redundant threading by bringing together the concepts of slice-level execution and value and control-flow locality into a novel partial redundant threading mechanism called SlicK.The purpose of redundant execution is to check the integrity of the outputs propagating out of the core (typically through stores). SlicK implements redundancy at the granularity of backward-slices of these output instructions and exploits value and control-flow locality to avoid redundantly executing slices that lead to predictable outputs, thereby avoiding redundant execution of a significant fraction of instructions while maintaining extremely low vulnerabilities for critical processor structures.We propose the microarchitecture of a backward-slice extractor called SliceEM that is able to identify backward slices without interrupting the instruction flow, and show how this extractor and a set of predictors can be integrated into a redundant threading mechanism to form SlicK. Detailed simulations with SPEC CPU2000 benchmarks show that SlicK can provide around 10.2% performance improvement over a well known redundant threading mechanism, buying back over 50% of the loss suffered due to redundant execution. SlicK can keep the Architectural Vulnerability Factors of processor structures to typically 0%-2%. More importantly, SlicK's slice-based mechanisms provide future opportunities for exploring interesting points in the performance-reliability design space based on market segment needs.

Despite the extensively researched physical principles, numerous published simulations on SiC drift step recovery diodes (SiC DSRD) and the practical implementation of SiC DSRD-based pulses, there are few kinds of research focusing on collaborative design between a SiC DSRD and its driving circuit. In this paper, a collaborative design method of a SiC DSRD and its driving circuit are presented. In addition, a detailed simulation is conducted to verify design considerations and to analyze the impact of driving parameter changes on the output pulse waveform. A pulse generator prototype with a self-developed SiC DSRD is implemented. The experimental results show that the circuit can output a peak voltage of 790 V on a matching load of 50 Ω, with a rise time of 520 ps (20%~80%), and can work at a 1 MHz repetition frequency rate with good stability.

The first part of this paper deals with the basic photodiode unit, its principle of operation, and the factors that affect the photodiode and array sensitivity. Experimental results of the planar Si p/sup +/-n photodiode are presented. Design and layout considerations including the integration time are also given. The second part of this paper deals with scanning of photodiode arrays. Detail design considerations are given for a static MOST ring counter. A dynamic shift register with clocked loads for integral scanning is also considered. Design considerations of a realized photosensing matrix with integral scanning are given. Finally, scanning problems of large arrays are briefly considered.

The primary goal of a power distribution system is to provide nominal voltages and power with minimal losses to meet consumer demands under various load conditions. In the distribution system, power loss and voltage uncertainty are the common challenges. However, these issues can be resolved by integrating distributed generation (DG) units into the distribution network, which improves the overall power quality of the network. If a DG unit with an appropriate size is not inserted at the appropriate location, it might have an adverse impact on the power system’s operation. Due to the arbitrary incorporation of DG units, some issues occur such as more fluctuations in voltage, power losses, and instability, which have been observed in power distribution networks (DNs). To address these problems, it is essential to optimize the placement and sizing of DG units to balance voltage variations, reduce power losses, and improve stability. An efficient and reliable strategy is always required for this purpose. Ensuring more stable, safer, and dependable power system operation requires careful examination of the optimal size and location of DG units when integrated into the network. As a result, DG should be integrated with power networks in the most efficient way possible to enhance power dependability, quality, and performance by reducing power losses and improving the voltage profile. In order to improve the performance of the distribution system by using optimal DG integration, there are several optimization techniques to take into consideration. Computational-intelligence-based optimization is one of the best options for finding the optimal solution. In this research work, a computational intelligence approach is proposed to find the appropriate sizes and optimal placements of newly introduced different types of DGs into a network with an optimized multi-objective framework. This framework prioritizes stability, minimizes power losses, and improves voltage profiles. This proposed method is simple, robust, and efficient, and converges faster than conventional techniques, making it a powerful tool of inspiration for efficient optimization. In order to check the validity of the proposed technique standard IEEE 14-bus and 30-bus benchmark test systems are considered, and the performance and feasibility of the proposed framework are analyzed and tested on them. Detailed simulations have been performed in “MATLAB”, and the results show that the proposed method enhances the performance of the power system more efficiently as compared to conventional methods.

this paper presents the analysis and design consideration of a transmitter topology that features being compact and low cost. Operation mode of this transmitter is analyzed in quantity and therefore the closed-form expressions with any duty cycle have been derived, which lead to the optimal design. The practical design considerations including components selection, efficiency optimization and thermal issue, form factor reduction, coupling factor variance, foreign object detection (FOD), and input voltage variance are discussed. And new design ideas are proposed. In addition, a parallel LC resonant tank as the receiver topology is analyzed. The proposed analysis and normalized design approach are verified by simulation and experimental results

The U.S. Army TACOM-TARDEC developed and validated a high-fidelity six-degree-of-freedom model to use in a trade study for the development of a prototype autonomous vehicle. The model captures realistic dynamics of the six-wheeled, skid-steered vehicle along with the electrical, thermal, and mechanical response of a detailed series hybrid-electric power system with in-hub drive motors, lithium-ion battery, and generator linked to a diesel engine. These components were modeled and integrated via extensive power and energy component libraries developed for use with a high-fidelity software tool for dynamics modeling. Further, the vehicle model’s entire complement of components was integrated in a flexible configuration that allowed them to be readily adjusted or swapped out so the user could use the model to ascertain the relative effects of modifying the vehicle’s structural or power system components on specific vehicle evaluation criteria. Such criteria include the vehicle’s performance with high-speed stability, skid steering stability, body pitch/roll/dive/squat characteristics, braking capability, road/soft-soil traversal, and steering maneuverability.The model captures both the on- and off-road mobility for the vehicle via use of an extensive library of various terrains including hard surface, sand, sandy loam, clay soil, and snow. Further, detailed waypointbased path navigation routines automate the vehicle’s traversal over a number of user-selectable courses including some established military courses such as Churchville-B, Perryman 1, 3, and A, and Munson with user-defined vehicle velocities. The model functions as an executable file run independent of any proprietary or close-source software; the user utilizes a simplified interface to vary any of the variables associated with the vehicle’s geometry, power system, course and speed to navigate, and terrain type applied to the course. The graphical view for the vehicle traversing the selected terrain is shown with an open source 3D graphics tool. The model was validated by applying the specifications in the model for the prototype vehicle of the first-generation of autonomous six-wheeled skid-steered vehicle, simulating the model in maneuvers identical to those the prototype vehicle performed, and comparing the simulated and actual results; the data matched and the model was successfully validated.The vehicle model was designed primarily for the trade study for the design of a specific vehicle, but was created with sufficient flexibility and capability for modeling future vehicles as well. The interchangeability of the vehicle models’ components and environments allow a user to modify or replace the vehicle’s power system components, chassis masses, tires, transmission, duty cycles, courses to traverse, and many other aspects of the vehicle. Thus the user can essentially model any vehicle with similar types of components or structures and use that model to determine the impact of those elements upon many vehicle design considerations such as mass requirements, volume constraints, power system requirements, wheels design, suspension characteristics, and controls. Several new vehicle models are already being developed using this model’s flexibility and capability.

Differential thermal analysis is employed to characterize new materials. The structure of a prototype of a differential thermal analysis instrument, based on a microcontroller is described. The design considerations of the temperature controller to vary the temperature of the heating unit at a constant rate are discussed. Experimental and simulation results are presented. I. INTRODUCTION Thermal analysis has been traditionally used in the characterization of clays and their natural and artificial mixtures. This technique in different forms, is also being increasingly applied in the characterization of polymers and plastics. The differential thermal analysis (DTA) is conducted to detect amongst other things, the endothermic or exothermic reactions that occur in the material under test, when the same is subjected to a specified constant heating rate. The test, in its essence, consists in monitoring the changes in the temperature of the sample under test with respect to the temperature of inert rcfcrence material when both are subjected to the same constant heating rate. The other thermal analysis tests which are more frequently used, in the field of polymers and plastics are differential scanning calorimetry (DSC), the therniomechanical analysis (TMA), the dynamic mechanical analysis (DMA) and the thermal gravimetric analysis (TGA) (I). This last is also useful in the field of clays and ceramics to determine quantitative relations of different phases in a typical thermal reaction which involves loss of some mass in the sample under test. A conventional typical DTA instrument (fig. 1) consist of a heating unit (HU), a programable temperature controller (TC), a sample holder (SH) temperature sensing thermocouples, aiid associated low drift d.c. amplifiers as well as a strip chart recorder (2,3). There is usually a provision for heating the sample to upto 1200 C at an adjustable constant heating rate varying from 2 C/min to 20 C/min. Typically the duration of the experiment may vary between 1 hour and 10 hours. In this paper, a compact prototype, based on a 16-bit microeontroller, for a DTA instrument, is proposed. The programable temperature control of the heating unit and acquisition of the differential temperature of sample under test w.r.t. the temperature of the reference material is done in the microcontroller. The design of the temperature controller for the Ku assembled in the laboratory, based on the experimentally determined model of the HU, is discussed. The simulation aiid experimental results for the P and PLD controllers are presented. The experimental results of a typical Merentia1 thermal analysis test conducted with the proposed prototype under the control of a P.C. compatible microcomputer are presented.