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Molecular psychiatry 07/2012; · 15.05 Impact Factor
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ABSTRACT: Energy efficient execution of applications is important for many reasons, e.g. time between battery charges, device temperature. Voltage and Frequency Scaling (VFS) enables applications to be run at lower frequencies on hardware resources thereby consuming less power. Real-time applications have deadlines that must be met otherwise their output is devalued. Dataflow modelling of real-time applications enables off-line verification of the application's temporal requirements. In this paper we describe a method to reduce the combined static and dynamic energy consumption using a Dynamic VFS (DVFS) technique for dataflow modelled real-time applications that may be mapped onto multiple hardware resources. We achieve this by using an application's static slack in order to perform DVFS while still satisfying the application's temporal requirements. We show that by formulating a dataflow modelled application and its mapping as a convex optimisation problem, with energy consumption as the objective function, the problem can be solved with a generic convex optimisation solver, producing an energy optimal constant frequency per application task. Our method allows task frequencies to be constrained such that, e.g. one frequency per application or per processor may be achieved.
Digital System Design (DSD), 2011 14th Euromicro Conference on; 10/2011
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ABSTRACT: Embedded Multiprocessor Systems-on-Chip (MPSoCs) commonly run multiple applications at once. These applications may have different time criticalities, i.e. non real-time, soft real-time, and firm or hard real-time. Application-level composability is used to provide each application with its own virtual platform, such that each application may be developed, verified, and executed independently, given its virtual platform specification. Composability of functional and temporal properties has been demonstrated in previous work. In this paper, we extend composability to include power management, where each application can manage its energy usage independently. Each application receives an independent energy and/or power budget, which it can manage as it sees fit, with its own application-specific power-management policy. Time, energy, and power budgets allocated to each application ensure that its power-management policy cannot cause any interference to the functional, timing, and power behaviours of other applications. We implement our technique on an existing composable and predictable hardware platform (CompSoC), and extend its Real-Time Operating System (OS) with a power-management infrastructure. Applications use a power-management API to communicate with the OS that implements time, energy, and power budgets. We demonstrate the applicability of our techniques by running several concurrent applications with their own power managers on an FPGA prototype.
Embedded Computer Systems (SAMOS), 2011 International Conference on; 08/2011
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ABSTRACT: Zenergy Power has been developing an inductive-type of fault current limiter (FCL) for electric power grid applications. The FCL employs a magnetically saturating reactor concept which acts as a variable inductor in an electric circuit. In March 2009 Zenergy Power, with funding from the California Energy Commission and the U.S. Department of Energy (DOE), installed an FCL in the Avanti distribution circuit of Southern California Edison's Shandin substation in San Bernardino, CA. Rated at 15 kV and 1,250 amperes steady-state, the “Avanti” device is the first superconductor FCL installed in a US utility. In January 2010, the “Avanti” device successfully limited its first series of real-world faults when the circuit experienced multiple single-phase and three-phase faults. After successfully validating the performance of a new “compact” saturated-core FCL, Zenergy Power received contracts to install a 12 kV, 1,250 amperes compact FCL in the CE Electric UK grid in early 2011 and a 138 kV, 1,300 amperes FCL at the Tidd substation of American Electric Power in late 2011.
IEEE Transactions on Appiled Superconductivity 07/2011; · 1.04 Impact Factor
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ABSTRACT: Applications, often with real-time requirements, are mapped onto Multiprocessor Systems on Chip (MPSoCs). Hard real-time applications require no deadline misses, and a formal modelling approach must be used to analyse the worst-case performance, which is complicated and time consuming. Such models are restricted to specific application behaviours and not generally applicable. Soft real-time applications such as video decoders often do not fit these models while having less strict requirements. An infrequent frame drop is barely noticeable, and a worst-case analysis is too pessimistic. For such applications it suffices to meet deadlines for a given set of traces. In this work we propose conservative simulation as an alternative approach to formal modelling for soft real-time applications. We introduce a hybrid simulation method which enables performance guarantees on a per-trace basis, without any modelling effort. Furthermore we evaluate an implementation of the described technique and compare it with an actual MPSoC instance implemented on an FPGA. Our results show that the simulation technique is conservative, with less than a 10% difference in timing compared to the actual implementation, for a software JPEG decoder.
Embedded Systems for Real-Time Multimedia (ESTIMedia), 2010 8th IEEE Workshop on; 11/2010
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ABSTRACT: The development and testing of an innovative and compact saturating-reactor High Temperature Superconductor Fault Current Limiter (HTS FCL) is described. The development includes an initial dry-type magnetic core design with iron cores partially encircled by an HTS DC coil and a recently completed oil-immersed design with magnetic cores enclosed in a metallic tank placed inside the warm bore of a rectangular HTS DC magnet. The first 15 kV HTS FCL was installed in Southern California Edison's grid in 2009 and the first transmission-class 138 kV Compact HTS FCL is planned to be in operation in American Electric Power's grid in 2011.
Power and Energy Society General Meeting, 2010 IEEE; 08/2010
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ABSTRACT: Multi-processors systems on chip (MPSOC) platforms emerged in embedded systems as hardware solutions to support the continuously increasing functionality and performance demands in this domain. Such a platform has to execute a mix of applications with diverse performance and timing constraints, i.e., real-time or non-real-time, thus different application schedulers should co-exist on an MPSOC. Moreover, applications share many MPSOC resources, thus their timing depends on the arbitration at these resources. Arbitration may create inter-application dependencies, e.g., the timing of a low priority application depends on the timing of all higher priority ones. Application inter-dependencies make the functional and timing verification and the integration process harder. This is especially problematic for real-time applications, for which fulfilling the time-related constraints should be guaranteed by construction. Moreover, energy and power management, commonly employed in embedded systems, make this verification even more difficult. Typically, energy and power management involves scaling the resources operating point, which has a direct impact on the resource performance, thus influences the application time behaviour. Finally, a small change in one application leads to the need to re-verify all other applications, incurring a large effort. Composability is a property meant to ease the verification and integration process. A system is composable if the functionality and the timing behaviour of each application is independent of other applications mapped on the same platform. Composability is achieved by utilising arbiters that ensure applications independence. In this paper we present the concepts behind a composable, scalable, energy-managed MPSOC platform, able to support different real-time and nonreal time schedulers concurrently, and discuss its advantages and limitations.
Optimization of Electrical and Electronic Equipment (OPTIM), 2010 12th International Conference on; 06/2010
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ABSTRACT: Modern implementations of discrete-time phase-locked loops (DT-PLLs) often contain delayed feedback. The delays are usually a side effect to pipelining, filtering, or other inner-loop mechanisms. Each delay increases the order of the system by introducing an additional pole to the closed-loop transfer function and, in many cases, makes the traditional type-2 loop equations obsolete. This brief describes how the second-order notions of damping and natural frequency can be applied to type-2 DT-PLLs in the presence of any number of delays. It provides equations for loop parameters that will provide a desired transient behavior based on damping and natural frequency, along with a test to ensure the accuracy of the results. The novelty of this brief is that loop parameters can be found in closed form and ensured to be accurate, without the need for human interaction, simulations, or numerical root-finding algorithms.
Circuits and Systems II: Express Briefs, IEEE Transactions on 01/2010; · 1.41 Impact Factor
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ABSTRACT: We describe an approach to building a highly configurable, semi-autonomous agent that can support users playing a variety of roles in a supply-chain trading environment. The agent's decision processes are composed of networks of simple services that are described using OWL ontology. The ontology describes both the abstract data structures that are produced and consumed by individual services, as well as the business meaning of these data elements. This approach supports goal-directed composition of services in order to generate performance dashboards, as well as direct injection of user input at arbitrary points in the network.
Commerce and Enterprise Computing, 2009. CEC '09. IEEE Conference on; 08/2009
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ABSTRACT: The Global DEM (GDEM) product is being generated from Advanced Space borne Thermal Emission and Reflection Radiometer (ASTER) data by Japan's Ministry of Economy, Trade, and Industry (METI) and the National Aeronautics and Space Administration (NASA). It is a snapshoot of the reflective surface of the earth during the time period of the mission, and is about 100 times more detailed than existing global elevation data, such as GTOPO 30[1] and GLOBE[2] and nine times more detailed than the existing SRTM[3, 4]. Up to now, only limited evaluation has been performed of the GDEM dataset. From what is known about the processing methodology it is expected that the Aster GDEM contains a significant number of anomalies that prevents immediate use for a wide range of applications.
08/2009
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M. Kato,
R. Nagarajan,
S. Murthy,
S. Corzine,
V. Dominic,
Hai Xu,
B. Taylor,
P. Evans,
J. Pleumeekers,
A. Dentai, [......],
R. Muthiah,
R. Salvatore,
C. Joyner,
J. Rossi,
R. Schneider,
M. Ziari, A. Nelson,
S. Grubb,
F. Kish,
D. Welch
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ABSTRACT: We review progress in the area of InP large scale photonic integrated circuits (LS-PICs). We will review transmitter and receiver PICs for digital optical networking.
Opto-Electronics and Communications Conference, 2008 and the 2008 Australian Conference on Optical Fibre Technology. OECC/ACOFT 2008. Joint conference of the; 08/2008
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ABSTRACT: To investigate if triage nurses could safely apply a set of clinical criteria, removing hard collars and spinal boards at initial triage assessment.
The Nexus clinical decision rules were applied by trained triage nurses to patients who attended the department with cervical collars and/or on spinal boards. Patients were excluded if they were felt to be in need of immediate medical assessment. Data were collected on the time to nursing assessment, time to medical assessment and time spent restrained. Patients were followed up until discharge and their radiological diagnosis confirmed. Hospital records were checked to ensure that no patients re-presented with injuries that had been missed at initial assessment.
In total, 112 patients were included in the study. Clinical criteria were met in 59 patients and their collar removed at triage assessment. For low risk patients, this reflects a mean reduction in time spent restrained of 23.3 minutes (p<0.005; 95% confidence interval 20.18 to 26.54). No patient who had a collar removed was found to have a significant injury.
Simple criteria can be applied by accident and emergency triage nurses to allow safe removal of cervical collars and spinal boards. The reduced time patients spent immobilised represents an important improvement in patient care.
Emergency Medicine Journal 04/2006; 23(3):214-5. · 1.44 Impact Factor
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ABSTRACT: Described in detail is a laser induced fluorescence system which has been successfully interfaced with two aircraft sampling platforms (i.e., Sabreliner jet and an L‐188C Electra). This system, which has been under development for four years, presently consists of the following major components: (1) a Nd–Yag laser driven oscillator–amplifier dye laser; (2) a sampling manifold with associated fluorescence detection optics; (3) an OH calibration chamber; (4) a laser beam steering assembly; and (5) sampling electronics and data processing hardware. During the last three years, this system has been flown some 50 000 air miles making tropospheric OH radical measurements over the latitude range of 70 °N to 57 °S. OH concentrations measured during these flights have ranged from 30 parts‐per‐quadrillion (3.7×10<sup>5</sup> molecules/cm<sup>3</sup>) at altitudes of 6 km to 0.8 parts‐per‐trillion (2.0×10<sup>7</sup> molecules/cm<sup>3</sup>) at 0.5 km. Computations have been completed which indicate that the existing aircraft system with modest modifications should also be capable of detecting natural tropospheric levels of NO, SO 2 , CH 2 O, NO 2 , HNO 2 , NO 3 , H 2 O 2 , and CS 2 by using both conventional laser‐induced fluorescence methodology and multiphoton techniques.
Review of Scientific Instruments 01/1980; · 1.37 Impact Factor
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Cali, Columbia.
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See http://srtm. csi. cgiar. org.
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ABSTRACT: Advanced III–V transistors require unprecedented low-resistance contacts in order to simultaneously scale bandwidth, fmax and ft with the physical active region [M.J.W. Rodwell, M. Le, B. Brar, in: Proceedings of the IEEE, 96, 2008, p. 748]. Low-resistance contacts have been previously demonstrated using molecular beam epitaxy (MBE), which provides active doping above 4×1019 cm−3 and permits in-situ metal deposition for the lowest resistances [U. Singisetti, M.A. Wistey, J.D. Zimmerman, B.J. Thibeault, M.J.W. Rodwell, A.C. Gossard, S.R. Bank, Appl. Phys. Lett., submitted]. But MBE is a blanket deposition technique, and applying MBE regrowth to deep-submicron lateral device dimensions is difficult even with advanced lithography techniques. We present a simple method for selectively etching undesired regrowth from the gate or mesa of a III–V MOSFET or laser, resulting in self-aligned source/drain contacts regardless of the device dimensions. This turns MBE into an effectively selective area growth technique.
Journal of Crystal Growth 311(7):1984-1987. · 1.73 Impact Factor
