53,190 research outputs found
Optimal system management of a water pumping and desalination process supplied with intermittent renewable sources
This paper aims at defining energy management strategy for a water pumping and desalination process which would be powered by a hybrid (solar PV & wind) renewable generation system. Several pumping subsystems for well pumping, water storage and desalination are coupled. The particularity of the proposed architecture with its management deals with the absence of electrochemical storage, only taking benefit of hydraulic storage in water tanks: in such an autonomous device, given a certain level of intermittent power following wind and sun irradiation conditions, and given hydraulic characteristics of water pumping subsystems, this study puts forward the prime importance of a water and power flow management optimization. For this purpose, both dynamic and quasi static models are proposed before stetting the management strategy based on optimal power dispatching. Subsequent results are analyzed in terms of robustness and performance
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Enterprise platform systems management security threats and mitigation techniques
Developers and technologists of enterprise systems such as servers, storage and networking products must constantly anticipate new cybersecurity threats and evolving security requirements. These requirements are typically sourced from marketing, customer expectations, manufacturing and evolving government standards. Much ongoing major research focus has been on securing the main enterprise system purpose functionality, operating system, network and storage. There appears, however, to be far less research and a growing number of reports of vulnerabilities in the area of enterprise systems management hardware and software subsystems. Many recent examples are within types of subsystems such as baseboard management controllers (BMCs), which are intricate embedded subsystems, independent of the host server system functionality. A BMC is typically comprised of a specialized system-on-a-chip, RAM, non-volatile storage, and sensors, and runs an embedded LINUX Operating System. The BMC’s primary roles are always increasing in scope including managing system inventory, system operational health, thermal and power control, event logging, remote console access, provisioning, performance monitoring, software updates and failure prediction and remediation. To compromise or create a denial of service of such subsystems has an increasing impact on equipment manufacturers and large and small enterprises. This report’s primary objective is to research real-world and theoretical hardware and software cyber-attack vectors on enterprise product platforms, inclusive of BMCs, BIOS and other embedded systems within such products. For each presented attack vector, best practices and suggestions for effective avoidance and mitigation are explored. Domains of particular interest are physical access security, hardware manipulation and secure boot protections against software image manipulation, BIOS recovery and secure field debug techniques.Electrical and Computer Engineerin
Deep Space Network information system architecture study
The purpose of this article is to describe an architecture for the Deep Space Network (DSN) information system in the years 2000-2010 and to provide guidelines for its evolution during the 1990s. The study scope is defined to be from the front-end areas at the antennas to the end users (spacecraft teams, principal investigators, archival storage systems, and non-NASA partners). The architectural vision provides guidance for major DSN implementation efforts during the next decade. A strong motivation for the study is an expected dramatic improvement in information-systems technologies, such as the following: computer processing, automation technology (including knowledge-based systems), networking and data transport, software and hardware engineering, and human-interface technology. The proposed Ground Information System has the following major features: unified architecture from the front-end area to the end user; open-systems standards to achieve interoperability; DSN production of level 0 data; delivery of level 0 data from the Deep Space Communications Complex, if desired; dedicated telemetry processors for each receiver; security against unauthorized access and errors; and highly automated monitor and control
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Firm technological responses to regulatory changes: A longitudinal study in the Le Mans Prototype racing
Despite the critical role of regulations on competition and innovation, little is known about firm responses and related effects on performance under regulatory contingencies that are permissive or restrictive. By longitudinally investigating hybrid cars competing in the Le Mans Prototype racing (LMP1), we counter-intuitively suggest that permissive regulations increase technological uncertainty and thus decrease the firms’ likelihood of shifting their technological trajectory, while restrictive regulations lead to the opposite outcome. Further, we suggest that permissive regulations favour firms that innovate their products by sequentially upgrading core and peripheral subsystems, while restrictive regulations—in the long term— favour firms upgrading them simultaneously. Implications for theory and practice are discussed
Two Case Studies of Subsystem Design for General-Purpose CSCW Software Architectures
This paper discusses subsystem design guidelines for the software architecture of general-purpose computer supported cooperative work systems, i.e., systems that are designed to be applicable in various application areas requiring explicit collaboration support. In our opinion, guidelines for subsystem level design are rarely given most guidelines currently given apply to the programming language level. We extract guidelines from a case study of the redesign and extension of an advanced commercial workflow management system and place them into the context of existing software engineering research. The guidelines are then validated against the design decisions made in the construction of a widely used web-based groupware system. Our approach is based on the well-known distinction between essential (logical) and physical architectures. We show how essential architecture design can be based on a direct mapping of abstract functional concepts as found in general-purpose systems to modules in the essential architecture. The essential architecture is next mapped to a physical architecture by applying software clustering and replication to achieve the required distribution and performance characteristics
A metaobject architecture for fault-tolerant distributed systems : the FRIENDS approach
The FRIENDS system developed at LAAS-CNRS is a metalevel architecture providing libraries of metaobjects for fault
tolerance, secure communication, and group-based distributed applications. The use of metaobjects provides a nice separation of concerns between mechanisms and applications. Metaobjects can be used transparently by applications and can be composed according to the needs of a given application, a given architecture, and its underlying properties. In FRIENDS, metaobjects are used recursively to add new properties to applications. They are designed using an object oriented design method and implemented on top of basic system services. This paper describes the FRIENDS software-based architecture, the object-oriented development of metaobjects, the experiments that we have done, and summarizes the advantages and drawbacks of a metaobject approach for building fault-tolerant system
System configuration and executive requirements specifications for reusable shuttle and space station/base
System configuration and executive requirements specifications for reusable shuttle and space station/bas
A 37.5-kW point design comparison of the nickel-cadmium battery, bipolar nickel-hydrogen battery, and regenerative hydrogen-oxygen fuel cell energy storage subsystems for low Earth orbit
Nickel-cadmium batteries, bipolar nickel-hydrogen batteries, and regenerative fuel cell storage subsystems were evaluated for use as the storage subsystem in a 37.5 kW power system for space station. Design requirements were set in order to establish a common baseline for comparison purposes. The storage subsystems were compared on the basis of effective energy density, round trip electrical efficiency, total subsystem weight and volume, and life
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