Tool For Design Of Systems Research Articles

Design tool for offgrid hydrogen refuelling systems for aerospace applications

To develop an environmentally acceptable refuelling solution for fuel cell-powered unmanned aerial systems (UASs) to operate in remote areas, hydrogen fuel must be produced on-site from renewable energy sources. This paper describes a Matlab-based simulation tool specifically developed to pre-design offgrid hydrogen refuelling systems for UAS applications. The refuelling system comprises a high concentrated PV array (CPV), an electrolyser, a hydrogen buffer tank and a diaphragm hydrogen compressor. Small composite tanks are also included for fast refuelling of the UAV platforms at any time during the year. The novel approach of selecting a CPV power source is justified on the basis of minimizing the system footprint (versus flat plat or low concentration PV), aiming for a containerized remotely deployable UAS offgrid refuelling solution.To validate the simulation tool a number of simulations were performed using experimental data from a prototype offgrid hydrogen refuelling station for UAVs developed by Boeing Research & Technology Europe. Solar irradiation data for a selected location and daily UAS hydrogen demands of between 2.8 and 15.8Nm3 were employed as the primary inputs, in order to calculate a recommended system sizing solution and assess the expected operation of the refuelling system across a given year. The specific energy consumption of the refuelling system obtained from the simulations is between 5.6 and 8.9kWhe per kg of hydrogen delivered to the UAVs, being lower for larger daily hydrogen demands. Increasing the CPV area and electrolyser size in order to supply higher daily hydrogen demands (e.g., above 10Nm3 H2 per day) improves the system operability. However this can imply excessive system size and costs, jeopardizing the techno-economic feasibility of a remotely deployable off-grid refuelling solution.

Kinematics and dynamics of Jansen leg mechanism: A bond graph approach

The Jansen mechanism is a one degree-of-freedom, planar, 12-link, leg mechanism that can be used in mobile robotic applications and in gait analysis. This paper presents the kinematics and dynamics of the Jansen leg mechanism. The forward kinematics, accomplished using circle intersection method, determines the trajectories of various points on the mechanism in the chassis (stationary link) reference frame. From the foot point trajectory, the step length is shown to vary linearly while step height varies non-linearly with change in crank radius. A dynamic model for the Jansen leg mechanism is proposed using bond graph approach with modulated multiport transformers. For given ground reaction force pattern and crank angular speed, this model helps determine the motor torque profile as well as the link and joint stresses. The model can therefore be used to rate the actuator torque and in design of the hardware and controller for such a system. The kinematics of the mechanism can also be obtained from this dynamic model. The proposed model is thus a useful tool for analysis and design of systems based on the Jansen leg mechanism.

Physical Modeling and Performance Bounds for Device-free Localization Systems

In this letter, an analytically tractable model based on diffraction theory is proposed to describe the perturbations of the electromagnetic propagation of radio signals caused by the presence of a moving object in the two-dimensional (2-D) area near the transmitting/receiving devices. This novel model is instrumental to the evaluation of non-cooperative device-free localization (DFL) systems as it allows to relate the received signal strength measurements of multiple radio links to the object size, orientation and position. The proposed model is validated experimentally using radio devices and it is used to derive closed-form fundamental limits to DFL accuracy, providing an analytical tool for DFL system design and network 2-D pre-deployment assessment.

Magnetic Stochastic Oscillators: Noise-Induced Synchronization to Underthreshold Excitation and Comprehensive Compact Model

In magnetic tunnel junctions specifically designed to be super-paramagnetic (S-MTJs), thermal noise induces stochastic switching between the parallel and anti-parallel states (Figure 1) [1]. As a consequence, they behave like stochastic oscillators, oscillating with non-constant period but with a well-defined average frequency. Although such junctions cannot be used for conventional memory applications, when exposed to spin transfer torque, they exhibit complex behavior that could be harnessed to implement original bio-inspired computing schemes. Notably, spin transfer torque can be used to influence the stability of states and therefore control the natural frequency of the stochastic oscillator. In this work, we investigate how this can lead to the phenomena of “stochastic resonance” and noise-induced synchronization of the stochastic oscillations to weak periodic excitations [2,3]. In order to design the bio-inspired systems exploiting such effects, accurate device models are needed. We therefore introduce a compact model written in the Verilog-A language and that can be used within standard integrated circuit design tools (Cadence platform) for system design, and that reproduces our experimental results.

Solar hydrogen power system for isolated passive house

Solar hydrogen power system for supplying isolated passive house with utility power energy and hydrogen fuel for personal transport has been established and discussed. Commercially available components such as photovoltaic module, proton exchange membrane fuel cell stack and electrolyzer stack were acquired. Appropriate control logic was developed. MATLAB/Simulink software has been used to simulate control logic and system components. The proof of the control logic and components models has been performed by simulations predefined scenarios, i.e. with and without solar irradiance and with given energy demands by the user. All of that can be used as valuable tool for any autonomous solar hydrogen system design of passive house.

A nonlinear lumped model for ultrasound systems using CMUT arrays.

We present a nonlinear lumped model that predicts the electrical input-output behavior of an ultrasonic system using CMUTs with arbitrary array/membrane/electrode geometry in different transmit-receive configurations and drive signals. The receive-only operation, where the electrical output signal of the CMUT array in response to incident pressure field is calculated, is included by modifying the boundary elementbased vibroacoustic formulation for a CMUT array in rigid baffle. Along with the accurate large signal transmit model, this formulation covers pitch-catch and pulse-echo operation when transmit and receive signals can be separated in time. In cases when this separation is not valid, such as CMUTs used in continuous wave transmit-receive mode, pulse-echo mode with a nearby hard or soft wall or in a bounded space such as in a microfluidic channel, an efficient formulation based on the method of images is used. Some of these particular applications and the overall modeling approach have been validated through comparison with finite element analysis on specific examples including CMUTs with multiple electrodes. To further demonstrate the capability of the model for imaging applications, the two-way response of a partial dual-ring intravascular ultrasound array is simulated using a parallel computing cluster, where the output currents of individual array elements are calculated for given input pulse and compared with experimental results. With its versatility, the presented model can be a useful tool for rapid iterative CMUT-based system design and simulation for a broad range of ultrasonic applications.

Simple thermal diverging model of the thin epitaxial layer of InP laser diodes

With increasing use of high-power LEDs (light-emitting diodes) and LDs (laser diodes), a critical issue arises regarding their thermal design due to the increasing thermal loss and temperature, and characterizing the thermal resistance Rth of the p-InP layer as a function of the layer thickness to optimize the thermal conductivity and optical loss is important. We propose a simple intuitive heat-transfer model with a diverging effective width, and the analytic form of Rth(d) agrees well with the Rth dataset that is simulated for most typical cases with various widths of the striped active layers and values of the p-InP thickness. Therefore, we propose a H (hyperbolic)-model that provides a simple analytic form of Rth,H(d) by using only the relaxation control parameter, h, as a convenient thermal design tool for various LD systems.

Performance Enhancement of Dynamic Cyclic Shift Code with Direct Detection and AND Subtraction Detection Technique of OCDMA

Optical code division multiple access system (OCDMA) has been important with increasing demands of high capacity and speed for communication in optical networks. Due to OCDMA technique high efficiency is achieved, hence fiber bandwidth is fully used .In this paper we will focus on DCS (Dynamic cyclic shift) code with their different detection technique using optiwave system design tool. Due to this codes we will eliminated MAI (multiple access interference) and improve BER (bit error rate) , PIIN( Phase induced intensity noise) and make orthogonality between users in the system .We will use two different detection technique i.e Direct detection technique and AND subtraction detection technique to implement the codes with different parameters. In this paper, the study of different parameters is based on conference a paper that is mainly demonstrated on an experiment to Enhancement a performance of DCS (Dynamic cyclic shift) code with there different parameter of OCDMA using optiwave system design tool.

Study and Design of 40 nW CMOS Temperature Sensor for Space Applications

In this paper, a novel CMOS temperature sensors based on sub-threshold MOS operation has been presented, which is designed for space and satellite applications. This proposed CMOS temperature sensor is enunciated good linearity between temperatures range from -55 O C to 150 O C with inaccuracy of 0.85 O C/V. This circuit is operated at supply 1V and static power consumption 40nW is achieved. The proposed circuit is based on the MOS threshold voltage and mobility. There are two type of sensor output in presented circuit first, voltage proportional to absolute temperature (PTAT) due to threshold voltage and second, negative temperature coefficient (NTC) due to mobility. This circuit is designed & simulated using Cadence analog & digital system design tools UMC90nm CMOS technology. The layout area of the circuit is 17.213μm 6.655μm. This is a low power and longer battery life for harsh environment, wireless sensor network applications etc.

Spatial conception of activities: a socio-cognitive perspective for simulating work practices.

People conceive their everyday affairs (their practices) as social actors in activities, in which they perceive, infer, move, manipulate objects, and communicate in some physical setting (e.g., going to the grocery to buy dinner). These behaviors are conceptually choreographed in an ongoing, usually tacit understanding of "what I'm doing now," encapsulating roles ("who I'm being now"), norms ("what I should be doing"; "how I should be dressed/talking/sitting"), and progress appraisals ("how well I'm doing"). Activity motives and modalities vary widely (e.g., waiting in line, listening to music, sleeping), all of which require time and occur in particular settings. Brahms is a multi-agent work systems design tool for modeling and simulating activities, used extensively to design aerospace work systems. For example, the Generalized Überlingen Model (Brahms-GÜM) simulates air transportation practices, focusing on how pilots and air traffic controllers interact with automated systems in safety-critical, time-pressured encounters. Spatial cognition is pervasive: scanning displays of multiple workstations; coordinating airspaces and flight paths; and prioritizing and timing interventions to maintain aircraft separations. Brahms-GÜM demonstrates how events may become unpredictable when aspects of the work system are missing or malfunctioning, making a routinely complicated system into one that is cognitively complex and becomes out of control. Normally, asynchronous processes become coupled in space and time, leading to difficulty comprehending the situation ("what is happening now") as a familiar multi-modal flow of events. Such examples illustrate the dynamics of spatial cognition inherent in our conceptually situated experience--our consciousness--of who we are and what we are doing.

A procedure to calculate the I – V characteristics of thin-film photovoltaic modules using an explicit rational form

Abstract Accurate models of the electrical behaviour of photovoltaic modules are effective tools for system design. One or two diode equivalent circuits have been widely used even though some mathematical difficulties were found dealing with implicit equations. In this paper, a new model based on a simple rational function, which does not contain any implicit exponential form, is presented. The model was conceived in order to be used with thin-film photovoltaic modules, whose current–voltage curves are characterised by very smooth shapes. The parameters of the model are evaluated by means of the derivatives of the issued characteristics in the short circuit and open circuit points at standard rating conditions, and assuming that the calculated current–voltage curve contains the rated maximum power point of the simulated panel. The capability of the model to calculate the current–voltage characteristic for values of the solar irradiance and cell temperature far from the standard rating conditions was verified for various thin-film technologies, such as CIS, CIGS, amorphous silicon, tandem and triple-junctions photovoltaic modules. A comparison with the results obtained by another rational model and other two-diode models, which were used to simulate the electrical behaviour of thin-film photovoltaic modules, is also presented.

Wavelet Processing for Neural Network Training Applied to Solar Radiation Forecasting

Photovoltaic power systems connected to the electrical grid are becoming an important element in the adoption of solar energy as a meaningful power source. However, radiation nonlinear behavior considerably affects photovoltaic systems performance and certainty. Solar radiation forecasting analysis is presented as an alternative to improve photovoltaic systems’ certainty and robustness. The training of an autoregressive neural network applied to solar radiation forecasting supported by wavelet processing is presented in this paper. Solar radiation data from 2010 to 2012 corresponding to Cajica, Colombia is used as input data to the system in order to get predicted radiation data from the following year. Validation of the results is performed by analysis of the real 2013 radiation data through mean squared error and linear regression. The results showed an accuracy of 93%, indicating that the proposed system can be used as a tool for the design of photovoltaic power systems in Colombia.

CALPHAD-Based Integrated Computational Materials Engineering Research for Materials Genomic Design

Due to materials genomic databases created by versatile computational tools in thermodynamics and kinetics, CALPHAD (CALculation of PHAse Diagrams) is one of the most important techniques in materials and manufacturing design. The CALPHAD method is neither empirical nor fundamental, but it plays a vital role to bridge engineering and science, industry and academia. 1,2 Evidently, CALPHAD-related models and experiments have been extensively adopted in materials and process design for both alloys and oxides. 2–4 There are three components in the materials innovation infrastructure of the Materials Genome Initiative (MGI) strategy: digital data, computational, and experimental tools. Such an idea can be well reflected in the framework of the modern CALPHAD research. As indicated in Fig. 1, modern CALPHAD modeling is based not only on experimental data but also on the combination of data with atomistic modeling, typically, quantum mechanical calculations. The integration of such techniques further extends spatial and temporal ranges of CALPHAD models. In this way, CALPHAD and its developed databases can be used in other simulation techniques for designing material properties by controlling phases and microstructure evolutions. It should be noted that experiments provide actual data resources for validating and calibrating multiscale simulation and modeling, which is indispensable in the modern CALPHAD infrastructure. Moreover, the amount of experimental needs is inversely proportional to the quality and accuracy of the computational models. Overall, the CALPHAD methodology can leverage various computational techniques to construct the integrated computational materials engineering (ICME) system design tools for materials genomic research. For the TMS 2015 Annual Meeting & Exhibition, 41 research papers were received for the dedicated MGI symposium, ‘‘CALPHAD-Based ICME Research for Materials Genomic Design,’’ sponsored by the Alloy Phases Committee and the Integrated Computational Materials Engineering Committee. Contributed talks covered (I) materials genomic design in engineering applications, (II) CALPHAD database construction and materials genomic data repository, (III) advanced processing and characterization in materials design, and (IV) CALPHADbased ICME model and tool development. Indeed, it is a formidable task for this JOM topic to represent the entire CALPHAD-based ICME research for materials genomic design. However, one may start learning the whole through seeing a part of it presented in this JOM issue. Furthermore, we hope that the MGI symposium during the TMS conference along with these papers housed in the current issue can stimulate more discussions on CALPHAD-based ICME research for materials genomic design. In the current special topic of JOM, three papers are contributed:

Integrating heterogeneous engineering knowledge and tools for efficient industrial simulation model support

Design of simulation models and their integration into industrial automation systems require knowledge from several heterogeneous data sources and tools. Due to the heterogeneity of engineering data, the integration of the tools and data are time-consuming and error-prone tasks nowadays. The key goal of this article is to provide an effective and efficient integration of heterogeneous data sources and tools as a knowledge basis to support dynamic simulation for industrial plants. The integrated knowledge is utilized both (i) in the design phase of simulation models for defining structure and interfaces of the models and (ii) in the runtime phase of industrial systems for model-driven configuration of the integrated environment. Reaching such goals with a manual approach or point-to-point integration is not beneficial as it may be possible for a few tools and data sources, but quickly gets very complex. A growing number of elements increases the risk of errors and the effort needed for integration. The proposed solution is based on a specification of a common data model to represent engineering knowledge and a service-oriented tool integration with the Engineering Service Bus. Engineering knowledge is integrated in a knowledge base implemented with ontologies in Web Ontology Language-Description Logic (OWL-DL). The proposed approach is demonstrated and evaluated on an educational hydraulic system. Major results of the article are: (i) a data model to represent engineering knowledge for dynamic industrial systems, (ii) the integration platform that, based on this model, integrates the tools for system design and runtime, and (iii) basic design-time and runtime processes for the integrated industrial simulations.

Geometric Approaches to State Feedback Control for Continuous and Switched Linear Systems

AbstractThe usability of underdetermined state feedback in the context of pole placement, eigenstructure assignment, stabilization and robustness analysis of continuous and switched linear systems is explored. Analytical tools for system design and analysis are discussed from the geometric perspective. Thereby, several new results are obtained and some well‐known ones are recovered and generalized by utilization of the computational methods based on the concept of invariance subspaces.

Analyzing Drive Cycles for Hybrid Electric Vehicle Simulation and Optimization

System design tools including simulation and component optimization are an increasingly important component of the vehicle design process, placing more emphasis on early stages of design to reduce redesign and enable more robust design. This study focuses on the energy use and power management simulations used in vehicle design and optimization. Vehicle performance is most often evaluated in simulation, physical testing, and certification using drive cycle cases (also known as dynamometer schedules or drive schedules). In vehicle optimization studies, the information included in each drive cycle has been shown to influence the attributes of the optimized vehicle, and including more drive cycles in simulation optimizations has been shown to improve the robustness of the optimized design. This paper aims to quantitatively understand the effect of drive cycles on optimization in vehicle design and to specify drive cycles that can lead to robust vehicle design with minimal simulation. Two investigations are performed in service of this objective; investigation 1 tests how different combinations of drive cycles affect optimized vehicle performance and design variables (DV); investigation 2 evaluates the use of stochastic drive cycles for improving the robustness of vehicle designs without adding computational cost to the design and optimization process.

Verilog-A behavioral model for resonance-modulated silicon micro-ring modulator.

We present an accurate behavior model for Si micro-ring modulators (MRM) based on Verilog-A, a standard simulation tool for electronic system design. Our model describes the electrical characteristics of the Si MRM using an equivalent circuit and the optical characteristics based on the couple-mode theory. The accuracy of our model is confirmed by comparing simulation results of our behavior model with the measurement results of a fabricated Si MRM. With this behavior model, co-simulation of Si MRM and electronic driving circuits in the standard electronic design environment can be easily performed.

Constrained Reachability and Controllability Sets for Planetary Precision Landing via Convex Optimization

This paper presents a convex optimizations-based method to compute the set of initial conditions from which a given landing accuracy to a target can be achieved (constrained controllability set) and the set of states that can be reached from a given set of initial states (constrained reachability set) for a planetary landing vehicle with all the relevant control and mission constraints. The proposed method is based on the lossless convexification of the powered-descent landing guidance problem and methods of convex optimization and computational geometry. These techniques are used to generate approximations that can be arbitrarily close to the actual reachability or controllability sets. The quantification of these sets allows evaluation of the feasibility of a prescribed landing accuracy for a given vehicle and an expected set of dispersions from the parachute descent phase of a planetary landing mission. Since these sets are generated systematically and quickly, a wide range of design options can be evaluated for different mission requirements. Consequently, the proposed method can enable lander vehicle design optimization as a reliable analysis tool for systematic design and system engineering.

ITADLS: An Interactive Tool for Analysis and Design of Linear Systems

Interactive software tools have proven as particularly useful techniques with high impact on education. This kind of tools make students more active and involved in their own learning process. The paper describes the basic functionality of ITADLS, an interactive tool for analysis and design of linear control systems. The tool, whose main feature is its simplicity and self-contained, has been developed using Sysquake, a MATLAB-like language with fast execution and excellent facilities for interactive graphics, and is delivered as a stand-alone executable that is readily accessible to students and instructors.

Interactive Models as a System Design Tool: Applications to System Project Management

Frequent and significant cost and schedule overruns in large aerospace and defense projects are hypothesized to be attributed to limitations on designers’ perception of complex systems. New design methods and tools to improve perception could reduce design effort. This paper extends an existing model of system project management to incorporate new methods for collaborative modeling and rapid sensitivity analysis using web- and browser-based technologies. A JavaScript-based API and model implementation in the system dynamics formalism replicate previous model results. Performance benchmarks demonstrate model execution in around 100 milliseconds on consumer hardware. Data storage and remote model execution services compose and query model results across executions. Browser-based user interfaces and visualizations allow users to interact with model components and provide batch model execution, tradespace exploration, sensitivity analysis, and time series comparison.