28 research outputs found

    Estimation and fault diagnosis for vehicle energy systems

    Get PDF
    Driven by a desire to achieve reduced carbon emissions and maintenance costs, along with an increase in efficiency and performance, electrification has become a major trend in modern vehicles. This increase in electrification is accompanied by an increase in thermal power dissipated due to electrical inefficiencies. Consequently, temperature regulation becomes a greater challenge for these safety-critical systems. Electrified vehicles consist of systems of systems that operate over a wide span of energy domains and timescales. To ensure their safe, reliable, and efficient performance, a holistic system perspective for estimation is needed. Accurate dynamic state estimation is critical for two main reasons: 1. Thermal management: This dissertation proposes a system perspective state estimation framework for complex multi-domain and multi-timescale dynamical systems. The framework consists of a multilevel hierarchical network of observers with each level having a unique update rate. To account for the significant interactions between subsystems, a novel bidirectional coordination strategy is developed. Sufficient conditions for the stability and convergence of the hierarchical network are derived. Experimental validation is conducted on a testbed representative of a fluid thermal management system of an electrified aircraft. Closed-loop simulation and experimental results confirm a reduction in computational cost compared to a conventional centralized observer and an increase in estimation accuracy compared to a decentralized observer which ignores coupling between subsystems. 2. Fault diagnosis: This dissertation proposes a robust system-perspective fault diagnosis framework for complex energy systems. Fault detection and isolation is derived from a set of structured residuals obtained from a bank of observers. Robustness is achieved by decoupling the unknown disturbances such as modeling error, linearization error, parameter variation, and noise from the residuals. The proposed approach is validated on a testbed representative of a fluid thermal management system of an electrified aircraft. Simulation and experimental results demonstrate successful fault detection and isolation with no false alarms or missed detections

    Secure storage systems for untrusted cloud environments

    Get PDF
    The cloud has become established for applications that need to be scalable and highly available. However, moving data to data centers owned and operated by a third party, i.e., the cloud provider, raises security concerns because a cloud provider could easily access and manipulate the data or program flow, preventing the cloud from being used for certain applications, like medical or financial. Hardware vendors are addressing these concerns by developing Trusted Execution Environments (TEEs) that make the CPU state and parts of memory inaccessible from the host software. While TEEs protect the current execution state, they do not provide security guarantees for data which does not fit nor reside in the protected memory area, like network and persistent storage. In this work, we aim to address TEEs’ limitations in three different ways, first we provide the trust of TEEs to persistent storage, second we extend the trust to multiple nodes in a network, and third we propose a compiler-based solution for accessing heterogeneous memory regions. More specifically, • SPEICHER extends the trust provided by TEEs to persistent storage. SPEICHER implements a key-value interface. Its design is based on LSM data structures, but extends them to provide confidentiality, integrity, and freshness for the stored data. Thus, SPEICHER can prove to the client that the data has not been tampered with by an attacker. • AVOCADO is a distributed in-memory key-value store (KVS) that extends the trust that TEEs provide across the network to multiple nodes, allowing KVSs to scale beyond the boundaries of a single node. On each node, AVOCADO carefully divides data between trusted memory and untrusted host memory, to maximize the amount of data that can be stored on each node. AVOCADO leverages the fact that we can model network attacks as crash-faults to trust other nodes with a hardened ABD replication protocol. • TOAST is based on the observation that modern high-performance systems often use several different heterogeneous memory regions that are not easily distinguishable by the programmer. The number of regions is increased by the fact that TEEs divide memory into trusted and untrusted regions. TOAST is a compiler-based approach to unify access to different heterogeneous memory regions and provides programmability and portability. TOAST uses a load/store interface to abstract most library interfaces for different memory regions

    Reliable and Safe Motion Control of Unmanned Vehicles

    Get PDF
    Unmanned vehicles (UVs) are playing an increasingly significant role in modern daily life. In the past decades, numerous commercial, scientific, and military communities across the world are developing fully autonomous UVs for a variety of applications, such as environmental monitoring and surveillance, post-disaster search and rescue, border patrol, natural resources exploration, and experimental platforms for new technologies verification. The excessive opportunities and threats that come along with these diverse applications have created a niche demand for UVs to extend their capabilities to perform more sophisticated and hazardous missions with greater autonomy, lower costs of development and operation, improved personnel safety and security, extended operational range (reliability) and precision, as well as increased flexibility in sophisticated environments including so-called dirty, dull, harsh, and dangerous missions. In order to successfully and effectively execute missions and meet their corresponding performance criteria and overcome these ever-increasing challenges, greater autonomy together with more advanced reliable and safe motion control systems are required to offer the critical technologies for ensuring intelligent, safe, reliable, and efficient control of UVs in the presence of disturbances, actuator saturation, and even actuator faults, especially for practical applications. This thesis concentrates on the development of different reliable and safe motion control algorithms/strategies applicable to UVs, in particular, unmanned aerial vehicles (UAVs) and unmanned surface vehicles (USVs). A number of contributions pertaining to the fault detection and diagnosis (FDD), fault-tolerant control (FTC), disturbance estimation and compensation, and actuator saturation avoidance have been made in this thesis. In addition to the control problems, this thesis also presents several guidance-related contributions, including adaptive observer-based line-of-sight (LOS) guidance law, time-varying lookahead distance scheme, piecewise path switching criterion for guiding a single UV, as well as a proportional-integral (PI) type of leader-follower formation guidance strategy for a group of UVs

    Combining SOA and BPM Technologies for Cross-System Process Automation

    Get PDF
    This paper summarizes the results of an industry case study that introduced a cross-system business process automation solution based on a combination of SOA and BPM standard technologies (i.e., BPMN, BPEL, WSDL). Besides discussing major weaknesses of the existing, custom-built, solution and comparing them against experiences with the developed prototype, the paper presents a course of action for transforming the current solution into the proposed solution. This includes a general approach, consisting of four distinct steps, as well as specific action items that are to be performed for every step. The discussion also covers language and tool support and challenges arising from the transformation

    Belle II Technical Design Report

    Full text link
    The Belle detector at the KEKB electron-positron collider has collected almost 1 billion Y(4S) events in its decade of operation. Super-KEKB, an upgrade of KEKB is under construction, to increase the luminosity by two orders of magnitude during a three-year shutdown, with an ultimate goal of 8E35 /cm^2 /s luminosity. To exploit the increased luminosity, an upgrade of the Belle detector has been proposed. A new international collaboration Belle-II, is being formed. The Technical Design Report presents physics motivation, basic methods of the accelerator upgrade, as well as key improvements of the detector.Comment: Edited by: Z. Dole\v{z}al and S. Un

    Architectural Techniques for Multi-Level Cell Phase Change Memory Based Main Memory

    Get PDF
    Phase change memory (PCM) recently has emerged as a promising technology to meet the fast growing demand for large capacity main memory in modern computing systems. Multi-level cell (MLC) PCM storing multiple bits in a single cell offers high density with low per-byte fabrication cost. However, PCM suffers from long write latency, short cell endurance, limited write throughput and high peak power, which makes it challenging to be integrated in the memory hierarchy. To address the long write latency, I propose write truncation to reduce the number of write iterations with the assistance of an extra error correction code (ECC). I also propose form switch (FS) to reduce the storage overhead of the ECC. By storing highly compressible lines in single level cell (SLC) form, FS improves read latency as well. To attack the short cell endurance and large peak power, I propose elastic RESET (ER) to construct triple-level cell PCM. By reducing RESET energy, ER significantly reduces peak power and prolongs PCM lifetime. To improve the write concurrency, I propose fine-grained write power budgeting (FPB) observing a global power budget and regulates power across write iterations according to the step-down power demand of each iteration. A global charge pump is also integrated onto a DIMM to boost power for hot PCM chips while staying within the global power budget. To further reduce the peak power, I propose intra-write RESET scheduling distributing cell RESET initializations in the whole write operation duration, so that the on-chip charge pump size can also be reduced

    SMART - IWRM - Sustainable Management of Available Water Resources with Innovative Technologies - Integrated Water Resources Management in the Lower Jordan Rift Valley : Final Report Phase II (KIT Scientific Reports ; 7698)

    Get PDF
    SMART was a multi-lateral research project with partners from Germany, Israel, Jordan and the Palestinian Territories. The overall goal was to develop a transferable approach for Integrated Water Resources Management (IWRM) in the water shortage region of the Lower Jordan Valley. The innovative aspect addressed all available water resources: groundwater and surface waters, but also wastewater, brackish water and flood water that need to be treated for use

    Pluto fast flyby spacecraft design and development

    Get PDF
    Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1994.Includes bibliographical references (p. 367-372).by J.G. Shirlaw.M.S
    corecore