Performance Analysis of Switched Control Systems Under Common-source Digital Upsets Modeled by MDHMM

Online peer-to-peer (P2P) lending is a new financing channel on which lenders are matched with borrowers using internet platform. Borrowers can get financing more easily, but it means higher credit risk to lenders, making credit scoring models a key tool for lending P2P platforms. The goal is to estimate the level risk (being good or bad borrower), from the collected informations of each applicant. One of the classification approaches is Multi dimensional Hidden Markov Model (MDHMM). The MDHMM parameters are usually estimated using Baum-Welch algorithm (BW). However, the Baum-Welch algorithm tends to arrive at local optimal points. In this paper a strategy called Variable neighborhood search (VNS), is proposed to addresses this problem. The hybrid model in which VNS algorithm is coupled with Baum-Welch algorithm for parameter estimation of MDHMM, is applied in credit scoring domain, using real peer-to-peer lending data. The experiments results show the performance efficiency of our model in comparison with classical and alternative machine learning models for credit scoring.

This paper presents a novel multi-dimensional hidden Markov model approach to tackle the complex issue of image modeling. We propose a set of efficient algorithms that avoids the exponential complexity of regular multidimensional HMMs for the most frequent algorithms (Baum-Welch and Viterbi) due to the use of a random dependency tree (DT-HMM). We provide the theoretical basis for these algorithms, and we show that their complexity remains as small as in the uni-dimensional case. A number of possible applications are given to illustrate the genericity of the approach. Experimental results are also presented in order to demonstrate the potential of the proposed DTHMM for common image analysis tasks such as object segmentation, and tracking.

Welcome to the DATE 08 Conference Proceedings. DATE combines the world's favourite electronic systems design conference and Europe's leading international exhibition for electronic design, automation and test, from system level hardware and software implementation right down to integrated circuit design. The DATE 08 event features a technical program with 77 sessions covering the latest developments in system design and embedded software, IC design/test methodologies and EDA tools, together with an exhibition with the leading EDA, silicon and IP providers showing their new products and services. Challenges that you all face or soon will face in your daily practice are the increasing design complexity of highly integrated systems, the introduction of reconfigurability and embedded software, and the control of power and variability in nanometer IC designs. All these issues will be addressed in this year's DATE event. For the 11th successive year DATE has prepared an exciting technical programme, with the help of the more than 400 members of the Technical Programme Committee, who dedicated their time to thoroughly review the 839 submissions in 37 topics, ranging from system level down to circuit design and covering all the most relevant application domains. The submissions are organised in 4 major areas: D --- Design Methods, Tools, Algorithms and Languages A --- Application Design T --- Test Methods, Tools and Innovative Experiences E --- Embedded Software After a thorough review and selection process (with an average of 5 reviews per paper), finally 198 regular papers were selected for presentation at the conference. Additionally, there are 46 Interactive Presentations that are organised in 5 IP sessions. Together with the invited special sessions (panels, embedded tutorials and hot topic sessions), this has resulted in a high-quality technical program. The technical program provides a wide but high-quality coverage of design, design automation and test topics, from the system level to the integrated circuit level. Compared with previous years, submissions in the Embedded Software track has increased by 50%, showing a clear trend towards a comprehensive system design focus with integrated hardware and software solutions. DATE has established itself firmly as a true Electronic System Design Conference. This year the conference is held in Germany, at the ICM in Munich and spans an entire working week from Monday March 10 to Friday March 14. On Monday, eleven pre-conference tutorials will be given. The three-full day tutorials cover topics of great interest for system design. The first tutorial deals with techniques to automatically realising embedded system from high-level functional models. The second tutorial addresses the different issues related to communication based design and architectures in automotive electronic systems. The third tutorial discusses several key concepts on system-level design and application mapping for wireless and multimedia MPSoC architectures. Furthermore, eight half-day tutorials are also given, which cover a wide spectrum of topics on specification, modelling, design and test. The main conference opens on Tuesday March 11, with two very interesting and complementary keynote speeches. Dominique Vernay, Chief Technical Officer for Thales, will talk about the challenges of embedded systems design, and Giovanni de Micheli, Professor at EPFL, will present his views on designing micro/nano systems for a safer and healthier tomorrow. On the same day, the Executive Track offers a series of business panels with executives discussing hot topics in design: the perils of 45 nanometers, the changes in EDA strategies from IDM, to fablite to fabless, and embedded systems level design strategies. DATE 08 will again offer two specific days related to special themes. On Wednesday March 12, a special full-day track is devoted to Automotive Electronics---Software and Architecture. This special-day track will focus on the challenges faced by the automotive supply chain with particular attention to system and software architecture design. It provides a comprehensive analysis of the evolution of automotive architectures, including ECUs, sensors and communication standards and discusses how new methods, tools and standards for interoperability and component-based design can deal with the increasing complexity of software systems and their need for reliability and guaranteed timely behaviour. In addition, it addresses to what degree existing standards, including AUTOSAR and FLEXRAY and model-based development, can support the development of safety and time-critical software. On Thursday March 13, a second special full-day track focuses on Dependable Embedded Systems. This track will address both conceptual and applied issues for design, analysis and validation of dependable embedded systems. The utility of embedded systems and services is based, in large part, on our depending on their sustained functionality in spite of the encountered operational or malicious disruptions. As the number of transient and also permanent disruptions (given the decreasing device geometries, higher device density, lower voltage latching, faster clocks etc) is expected to increase substantially, this will not only be a key issue for the hardware community but also the systems community in general. Solutions using a combination of hardware and software might be more effective than hardware-only or software-only solutions. This track focuses on both conceptual and applied issues for design, analysis and validation of dependable embedded systems. Besides these special tracks, the main conference is organized in six parallel tracks of sessions, three devoted to design methods, tools, algorithms and languages, one to application design, one to test methods, tools and innovative experiences, and finally one to embedded software. The presentations of the selected regular papers in these parallel tracks are complemented by nine Special Sessions and two Invited Industrial Sessions. The special sessions are organized in the form of panels, hot topics, and embedded tutorials. The topics to be covered include quantitative evaluation for embedded systems design, design and manufacturing at 32 and 22nm, software for wireless networked embedded systems, test challenges for low power devices, quantitative productivity measurement in IC design, and 3D Integration. The two invited industrial sessions deal with industrial system designs in transportation and information technologies. To emphasise that DATE is the major event for the designers, DATE 08 features also invited sessions where Europe's famous consumer industry presents their best designs and design practices. Friday March 14 is the day for the DATE workshops. DATE 08 offers workshops on current and emerging important issues in design, test, EDA and software to complement the regular conference. They provide a unique opportunity for the various research and design communities to spend a day discussing the latest and the best, sharing their experiences and visions. This year's workshop program includes eight workshop themes. Four workshops are related to software engineering, ranging from dependable software to modelling, analysis and development tools. Four other workshop themes cover a variety of topics such as the impact of process variations on design and test, the merging world of Nano-Electro-Mechanical Systems, new directions in high level synthesis, and heterogeneous reconfigurable hardware. Each workshop features presentations, invited or submitted, from highly distinguished academic and industrial researchers. Finally, throughout the conference days, DATE offers a comprehensive overview of commercial design and verification tools in its large exhibition hall. Exhibitors include EDA vendors, silicon, FPGA and IP providers showing their new products and services. In addition, there is an Exhibition Theatre featuring talks from engineering managers of the leading electronic manufacturers on first-hand design experiences of commercial EDA tools. New this year is the European projects village where different European and large government funded projects will be able to show their ongoing research and results to the design community and have the opportunity for internal meetings and discussions. The DATE week will be also an opportunity for students and universities to show their research work, through the PhD Forum on Monday evening and the University Booth where hardware and software demonstrations will be shown by different universities on a rotation schedule. The DATE 08 event's program will be particularly attractive to industrial designers, at analog, IC, FPGA and embedded system level, as well as software designers, to researchers and academics as well as to design managers, and an increasing attendance is expected. We therefore invite you to take full advantage of the many opportunities offered to you by DATE 08, to extend your knowledge and/or business in electronic system's design and to exploit the abundant networking possibilities offered to socialise with colleagues, including fringe meetings and a memorable social party with bands and dancing. We hope that you will all enjoy the DATE 08 Conference and Exhibition.

This paper focuses on the methodology analysis for the stability and the corresponding tracking performance of a closed-loop digital jump linear control system with a stochastic switching signal. The method is applied to a flight control system. A distributed recoverable platform is implemented on the flight control system and subject to independent digital upsets. The upset processes are used to stimulate electromagnetic environments. Specifically, the paper presents the scenarios that the upset process is directly injected into the distributed flight control system, which is modeled by independent Markov upset processes and independent and identically distributed (IID) processes. A theoretical performance analysis and simulation modelling are both presented in detail for a more complete independent digital upset injection. The specific examples are proposed to verify the methodology of tracking performance analysis. The general analyses for different configurations are also proposed. Comparisons among different configurations are conducted to demonstrate the availability and the characteristics of the design.

We review practical case studies of a developing method of highly reliable real-time embedded control systems using a CPU model-based hardware/software co-simulation. We take an approach that enables us to fully simulate a virtual mechanical control system including a mechatronics plant, microcontroller hardware, and object code level software. This full virtual system approach simulates control system behavior, especially that of the microcontroller hardware and software. It enables design space exploration of microarchitecture, control design validation, robustness evaluation of the system, software optimization before components design. It also avoids potential problems. The advantage of this work is that it comprises all the components in a typical control system, enabling the designers to analyze effects from different domains, for example mechanical analysis of behavior due to differences in controller microarchitecture. To further improve system design, evaluation and analysis, we implemented an integrated behavior analyzer in the development environment. This analyzer can graphically display the processor behavior during the simulation without affecting simulation results such as task level CPU load, interrupt statistics, and the software variable transition chart. It also provides useful information on the system behavior. This virtual system analysis does not require software modification, does not change the control timing, and does not require any processing power from the target microcontroller. Therefore this method is suitable for real-time embedded control system design, in particular automotive control system design that requires a high level of reliability, robustness, quality, and safety. In this study, a Renesas SH-2A microcontroller model was developed on a CoMET™platform from VaST Systems Technology. An electronic throttle control (ETC) system and an engine control system were chosen to prove this concept. The electronic throttle body (ETB) model on the Saber® simulator from Synopsys® and the engine model on MATLAB®/Simulink®simulator from MathWorks can be simulated with the SH-2A model using a newly developed co-simulation interface between MATLAB®/Simulink® and CoMET™. Though the SH-2A chip was being developed as the project was being executed, we were able to complete the OSEK OS development, control software design, and verification of the entire system using the virtual environment. After releasing a working sample chip in a later stage of the project, we found that such software could run on both actual ETC system and engine control system without critical problem. This demonstrates that our models and simulation environment are sufficiently credible and trustworthy.

Using Bayesian networks in reliability evaluation for subsea blowout preventer control system

The increasing demand for reliable electricity in off-grid regions, particularly in remote areas, calls for innovative solutions. This project focuses on the integration of Pumped Storage Hydropower (PSH) with solar photovoltaic (PV) systems, aiming to provide a clean, sustainable, and stable energy solution. The primary goal is to design and develop a small-scale hybrid system that utilizes solar energy to pump water into an elevated reservoir, which can then be released to generate electricity via a turbine when solar generation is low or unavailable. An Arduino-based monitoring system was developed to track the performance of both the solar panel and the hydro generator. The system was designed, simulated, and tested under real-world conditions. Results indicate that although the system demonstrates potential for off-grid applications, the small-scale PSH prototype is less efficient compared to direct battery-based solar storage in terms of consistency and output power. The findings suggest that improvements in system design, turbine efficiency, and storage capacity are required to enhance the performance and reliability of the hybrid system. The outcomes highlight the viability of hybrid renewable systems for sustainable off-grid electrification but also indicate areas for future research, particularly in optimizing system design and scaling for broader applications.

The article provides a review of design methods for heterogeneous computer information systems and critical application networks, analyzes requirements, provides a description of information technologies, their components, conditions of use, results of their application. A method for the computer-aided design of heterogeneous computer systems and critical application networks is proposed when operational tasks are included in the control system. The analysis of features arising during reconfiguration is carried out. The modern basic technical and software of computer systems for critical applications are analyzed. The general requirements for computer systems of critical applications and their components are formulated. The development trends and existing needs of computer systems and networks of critical application are determined. Based on the analysis of heterogeneous computer networks and theoretical generalization of work in the field of computer-aided design of critical application systems, the authors have developed a method for the computer-aided design of heterogeneous computer systems and critical-use networks.

It is generally accepted that active control systems provide better structural performance when compared to their passive counterparts. On the other hand, the design of active control systems based on linear control theory is highly dependent on the structural properties. For this reason, their performance is expected to be affected more severely by variations in structural properties compared to those of passive systems. These variations can occur due to nonlinear structural behavior, or even before that due to uncertainties in the estimation of these properties and in numerical modeling. The present work is an investigation of the dependency of various control systems used for supplemental energy dissipation to the changes in structural properties. For this purpose, the performance degradations of most common control systems are studied for structures entering their nonlinear response range. The considered control systems include active control using linear quadratic regulator algorithm and passive control using viscous fluid dampers and yielding devices. These control systems are optimized separately for linear and nonlinear structures by minimizing performance indices based on inter-story drift and absolute acceleration response. It is shown that among these control systems, viscous dampers are affected the least by the alteration of structural properties, which may further support their utilization contrary to the more costly active control systems. It is also shown that the amount of performance degradation depends on the selected structural performance index, and more importantly, the severity of the earthquake excitation.

Guest Editorial

Model-based development (MBD), which utilizes system models to design complex products, has received increasing attention. However, an advanced control system design scheme is required to accurately control the developed products under harsh conditions for practical usage. This paper proposes a control system that integrates a data-driven compensator (DDC) with a model-based control (MBC) system design. The proposed method considers a hierarchical control structure comprising an upstream control system based on the MBC design approach and a downstream control system that includes a plant control loop with a DDC. The proposed system can always maintain the desired performance by driving the MBC based on an ideal model because the downstream control system, DDC, maintains the characteristics of the ideal model even if the plant properties change owing to changes in operational and/or environmental conditions. In this study, the design scheme for unifying models and data in the MBD process is called smart MBD (S-MBD), and the proposed control system design scheme is based on the S-MBD approach. The effectiveness of the proposed hierarchical control system is verified by applying it to a hydraulic excavator.

The controlled atmospheric re-entry associated with the precision soft-landing of Reusable Launch Vehicles (RLVs) on Earth is very challenging as it depends on multiple parameters [1]. Over the last decade, the cost-effectiveness of such a technology has been finally demonstrated with the successful recoveries of SpaceX’s Falcon 9 first-stage rocket first [2], then followed by other companies such as the Rocket Lab’s Electron micro-launcher [3]. This breakthrough has been made possible by the development of advanced and robust computational methods able to generate in real time the flight conditions and to command the optimal vehicle's deflections accordingly to achieve a safe pinpoint landing. Indeed, during an Earth atmospheric re-entry, the vehicle is subjected to fast system dynamics changes partly induced by external loads associated with the terrestrial environment (e.g., lift, drag, wind and gusts), but also by the actuation commands to answer the landing constraints satisfaction and the vehicle integrity preservation. All those involve uncertainties and nonlinearities, which lead to vehicle’s instability and therefore give reason why for a highly performant Guidance, Navigation and Control system implementation [4]. More particularly, one of the critical aspects is the design of a robust control strategy capable of counteracting the previously defined disturbances and uncertainties while satisfying the strict accuracy requirements associated with the pinpoint landing [5]. As demonstrated by the current state-of-the-art on control design for launchers [6-7], the classical linear control theory represents a rich heritage with a lot of applications. This choice was motivated by its relative easiness of implementation and the possibility to use gain-scheduling techniques to adapt to nonlinear systems. Nevertheless, these techniques are well-adapted to the control system design of single-input single-output systems, such as for example a reusable rocket using a Thrust Vector Control (TVC) system as the unique actuator. The implementation of multiple-input multiple-output control systems becomes then complex since every channel is addressed in a single-loop fashion. This capability is however required for the future generation of reusable rocket, using also aerodynamic steering based on fins in addition to the TVC system for enhancing control authorities. Moreover, model uncertainties are not accurately considered in the design process, developed only with nominal conditions and stability margin requirements. For all these reasons, it results in an extensive (both in terms of time and cost) Verification and Validation campaign with many iterations and Monte-Carlo analyses to assess the performance and robustness of the control system. To overcome these drawbacks, the H-infinity family of methods, introduced a few years ago [8], provides with a powerful solution for robust control design. It relies on defining the control requirements in the frequency domain in terms of weighting functions and minimising the maximum gain of the resulting weighted system from the exogenous inputs to the outputs to be controlled. Moreover, the control-plant interaction is modelled through a Linear Fractional Transformation (LFT) representing the feedback action. Finally, the structured H-infinity method [9] allows to directly impose a specific control structure – like a Proportional-Integral-Derivative (PID), enabling the re-use of gain-scheduling techniques – and to consider parametric uncertainties for enhanced robustness. This paper studies the synthesis of a robust control system via structured H-infinity for the RLV atmospheric re-entry problem. First, the nonlinear 6-Degree-of-Freedom (6-DoF) RLV re-entry dynamics are simplified into a linear model and then linearised along a reference trajectory to get the nominal LFT of the system, then augmented with parametric uncertainties. The model covers the atmospheric re-entry and vertical landing of a first-stage rocket equipped with a TVC system and steerable planar fins. The controllers are built at different points of the re-entry trajectory, using the structured H-infinity framework through PID-like structures. Weighting functions considering the control objectives and requirements of a realistic RLV re-entry scenario are implemented. A robust stability analysis of the obtained system is performed via classical stability margins and structured singular value. Finally, the controllers are gain-scheduled and validated via Monte-Carlo analyses, using a nonlinear 6-DoF RLV re-entry dynamics simulator equipped with successive convex optimisation guidance. The performance of the resulting guidance and control architecture is compared with the baseline developed in previous works [10], using a TVC system only and classical linear feedback control through gain-scheduled PID controllers. This study lies within the ASCenSIon (Advancing Space Access Capabilities - Reusability and Multiple Satellite Injection) project, an innovative training network funded within H2020.

Virtual reality (VR) applications for surgical planning and mentoring are currently becoming more widespread. Within these fields of applications, haptic systems are crucial to help the understanding of the feedback provided by the tissue during the interaction with the surgical tool. The accuracy of the VR scenario is related to many aspects, among them the ability of the haptic device to provide the force feedback and thus the adoption of proper characterization and modeling of the soft tissue behavior during deformation. This paper presents the current development concerning a VR environment to be equipped with a force feedback haptic device to simulate and experience clamping in colorectal surgery. The reaction at the clamp handle is provided starting from a FEA of the contact between the surgical tool and the tissue, coupled with the kinematic analysis of the mechanism. Connecting the virtual scenario to a microcontroller board, the reaction force is applied to the the haptic device, shaped as a clamping tool handle, so that the user may experience the tissue impedence during clamping. By simulations made through Simscape, a concept is evaluated according to some simulation paths that involve common scenarios of the virtual reality experience (such as collision, partial or total clamping operation). The novelty of the research regards the system design oriented to increase the accuracy of the soft tissue material behaviour through a preliminary off-line dedicated FEA investigation. Through Simulink simulations, the system design is verified so that the VR system set-up may be carried out. The results highlighted: (a) a good correspondence among the theoretical study of the reference kinematism that the haptic device must reproduce; (b) the implementation of a bilinear material model, derived off-line from FEA, is suitable to capture hyperelastic and geometric non-linearities of the soft tissue; (c) the feasibility of the open loop haptic control in accordance to the explored kinematism. The final goal of the research is to propose a system design approach able to tune the VR experince for teaching and mentoring through a in-house set-up easy to be tailored.

Sistem güvenilirliği, iletişim ve elektronik sistemler gibi ileri teknolojiye sahip modern mühendislik sistemlerinin tasarımı ve analizinde yaygın olarak kullanılan önemli ölçütlerden biridir. Günlük hayatımıza giren, çoğu çalışma alanında ve sosyal yaşamda kullandığımız uygulamaları doğrudan etkileyen altyapı tasarım problemlerinin bir kısmı güvenilirlik ölçütünü dikkate alan eniyileme problemi olarak tanımlanmaktadır. Bu nedenle bu tür problemlerin çözümü, farklı disiplinlerde çalışan birçok araştırmacının yoğun ilgisini çekmektedir. Sistem güvenilirliğinin eniyilenmesi için alan yazında yaygın olarak kullanılan Yedek Bileşen Tahsis Problemi (YBTP), sistemde yer alan bileşenlere paralel olarak yerleştirilen kullanıma hazır bileşenler ile yeni sistemlerin tasarlanması olarak tanımlanabilir. Böylece, güvenilirlik başarım ölçütü dikkate alınarak daha yüksek güvenilirlik değerine sahip sistem tasarımlarının elde edilmesi sağlanabilmektedir. Sistem özelliklerine bağlı olarak seçilen uygun yöntemle sistemin güvenilirlik değeri elde edilir. Bu çalışmada, artan arıza ve tamir oranlarının dikkate alındığı YBTP’de sistem güvenilirliğini gerçekçi bir yaklaşımla tahmin etmek için Kesikli Olaylı Benzetim (KOB) modeli, sistemin eniyilenmesi için ise Genetik Algoritma (GA) geliştirilmiştir. KOB modelinin geçerliliği test problemleri üzerinde gösterilmiştir. Önerilen yaklaşımla, YBTP için daha yüksek güvenilirliğe sahip sistem tasarımlarının daha düşük maliyetlerle elde edilebilmesi sağlanmıştır.

Fluid Power Control Systems are mostly used in power plants. System design may change according to the required application and specified output quality. Mathematical model is important to get accurate expectation for system performance. Static and dynamic response of a fluid power control system under different operating conditions, considering supply pressure and temperature variation has been investigated. Different system designs implementing different system stiffness and different types of control valves have been constructed in a linear displacement control system, then experimented and evaluated. Sequence and time of operations has been controlled using PLC controller. Conclusions reveal that the power consumed could be decreased by simplifying system design using one high-response valve instead of two low-response valves. In addition, system dynamics could be improved from 50 % up to 79 % depending on working conditions. Mathematical model for the control system has been predicted, descending from the linear theoretical relationship between flow rate and valve opening according to Bernoulli equation. Supply pressure variation and flow force effects have been considered. The predicted relationship achieved remarkable agreement with the experimental performance of the system.Copyright © 2012 by ASME