Sample records for processor sharing queue

  1. Ordering of guarded and unguarded stores for no-sync I/O

    DOEpatents

    Gara, Alan; Ohmacht, Martin

    2013-06-25

    A parallel computing system processes at least one store instruction. A first processor core issues a store instruction. A first queue, associated with the first processor core, stores the store instruction. A second queue, associated with a first local cache memory device of the first processor core, stores the store instruction. The first processor core updates first data in the first local cache memory device according to the store instruction. The third queue, associated with at least one shared cache memory device, stores the store instruction. The first processor core invalidates second data, associated with the store instruction, in the at least one shared cache memory. The first processor core invalidates third data, associated with the store instruction, in other local cache memory devices of other processor cores. The first processor core flushing only the first queue.

  2. Parallel discrete event simulation: A shared memory approach

    NASA Technical Reports Server (NTRS)

    Reed, Daniel A.; Malony, Allen D.; Mccredie, Bradley D.

    1987-01-01

    With traditional event list techniques, evaluating a detailed discrete event simulation model can often require hours or even days of computation time. Parallel simulation mimics the interacting servers and queues of a real system by assigning each simulated entity to a processor. By eliminating the event list and maintaining only sufficient synchronization to insure causality, parallel simulation can potentially provide speedups that are linear in the number of processors. A set of shared memory experiments is presented using the Chandy-Misra distributed simulation algorithm to simulate networks of queues. Parameters include queueing network topology and routing probabilities, number of processors, and assignment of network nodes to processors. These experiments show that Chandy-Misra distributed simulation is a questionable alternative to sequential simulation of most queueing network models.

  3. Parallel discrete event simulation using shared memory

    NASA Technical Reports Server (NTRS)

    Reed, Daniel A.; Malony, Allen D.; Mccredie, Bradley D.

    1988-01-01

    With traditional event-list techniques, evaluating a detailed discrete-event simulation-model can often require hours or even days of computation time. By eliminating the event list and maintaining only sufficient synchronization to ensure causality, parallel simulation can potentially provide speedups that are linear in the numbers of processors. A set of shared-memory experiments, using the Chandy-Misra distributed-simulation algorithm, to simulate networks of queues is presented. Parameters of the study include queueing network topology and routing probabilities, number of processors, and assignment of network nodes to processors. These experiments show that Chandy-Misra distributed simulation is a questionable alternative to sequential-simulation of most queueing network models.

  4. An architecture for real-time vision processing

    NASA Technical Reports Server (NTRS)

    Chien, Chiun-Hong

    1994-01-01

    To study the feasibility of developing an architecture for real time vision processing, a task queue server and parallel algorithms for two vision operations were designed and implemented on an i860-based Mercury Computing System 860VS array processor. The proposed architecture treats each vision function as a task or set of tasks which may be recursively divided into subtasks and processed by multiple processors coordinated by a task queue server accessible by all processors. Each idle processor subsequently fetches a task and associated data from the task queue server for processing and posts the result to shared memory for later use. Load balancing can be carried out within the processing system without the requirement for a centralized controller. The author concludes that real time vision processing cannot be achieved without both sequential and parallel vision algorithms and a good parallel vision architecture.

  5. Efficient accesses of data structures using processing near memory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jayasena, Nuwan S.; Zhang, Dong Ping; Diez, Paula Aguilera

    Systems, apparatuses, and methods for implementing efficient queues and other data structures. A queue may be shared among multiple processors and/or threads without using explicit software atomic instructions to coordinate access to the queue. System software may allocate an atomic queue and corresponding queue metadata in system memory and return, to the requesting thread, a handle referencing the queue metadata. Any number of threads may utilize the handle for accessing the atomic queue. The logic for ensuring the atomicity of accesses to the atomic queue may reside in a management unit in the memory controller coupled to the memory wheremore » the atomic queue is allocated.« less

  6. Marine Vessel Traffic System

    DTIC Science & Technology

    2001-06-19

    Queue Get Put The MutexQ module provides primitive queue operations which synchronize access to the queues and ensure queue structure integrity...interface provides for synchronous data rates ranging from 64 Kbps to 1.536 Mbps, while an RS-232 interface accommodates asynchronous data up to...interface VME Communications processor 57 and 8-channel serial I/O board. This board set provides a 68040 processor and 8-channels of synchronous

  7. A Low-Power Instruction Issue Queue for Microprocessors

    NASA Astrophysics Data System (ADS)

    Watanabe, Shingo; Chiyonobu, Akihiro; Sato, Toshinori

    Instruction issue queue is a key component which extracts instruction level parallelism (ILP) in modern out-of-order microprocessors. In order to exploit ILP for improving processor performance, instruction queue size should be increased. However, it is difficult to increase the size, since instruction queue is implemented by a content addressable memory (CAM) whose power and delay are much large. This paper introduces a low power and scalable instruction queue that replaces the CAM with a RAM. In this queue, instructions are explicitly woken up. Evaluation results show that the proposed instruction queue decreases processor performance by only 1.9% on average. Furthermore, the total energy consumption is reduced by 54% on average.

  8. Operating System Support for Shared Hardware Data Structures

    DTIC Science & Technology

    2013-01-31

    Carbon [73] uses hardware queues to improve fine-grained multitasking for Recognition, Mining , and Synthesis. Compared to software ap- proaches...web transaction processing, data mining , and multimedia. Early work in database processors [114, 96, 79, 111] reduce the costs of relational database...assignment can be solved statically or dynamically. Static assignment deter- mines offline which data structures are assigned to use HWDS resources and at

  9. A microprocessor based high speed packet switch for satellite communications

    NASA Technical Reports Server (NTRS)

    Arozullah, M.; Crist, S. C.

    1980-01-01

    The architectures of a single processor, a three processor, and a multiple processor system are described. The hardware circuits, and software routines required for implementing the three and multiple processor designs are presented. A bit-slice microprocessor was designed and microprogrammed. Maximum throughput was calculated for all three designs. Queue theoretic models for these three designs were developed and utilized to obtain analytical expressions for the average waiting times, overall average response times and average queue sizes. From these expressions, graphs were obtained showing the effect on the system performance of a number of design parameters.

  10. Parallel discrete-event simulation of FCFS stochastic queueing networks

    NASA Technical Reports Server (NTRS)

    Nicol, David M.

    1988-01-01

    Physical systems are inherently parallel. Intuition suggests that simulations of these systems may be amenable to parallel execution. The parallel execution of a discrete-event simulation requires careful synchronization of processes in order to ensure the execution's correctness; this synchronization can degrade performance. Largely negative results were recently reported in a study which used a well-known synchronization method on queueing network simulations. Discussed here is a synchronization method (appointments), which has proven itself to be effective on simulations of FCFS queueing networks. The key concept behind appointments is the provision of lookahead. Lookahead is a prediction on a processor's future behavior, based on an analysis of the processor's simulation state. It is shown how lookahead can be computed for FCFS queueing network simulations, give performance data that demonstrates the method's effectiveness under moderate to heavy loads, and discuss performance tradeoffs between the quality of lookahead, and the cost of computing lookahead.

  11. Queueing models for token and slotted ring networks. Thesis

    NASA Technical Reports Server (NTRS)

    Peden, Jeffery H.

    1990-01-01

    Currently the end-to-end delay characteristics of very high speed local area networks are not well understood. The transmission speed of computer networks is increasing, and local area networks especially are finding increasing use in real time systems. Ring networks operation is generally well understood for both token rings and slotted rings. There is, however, a severe lack of queueing models for high layer operation. There are several factors which contribute to the processing delay of a packet, as opposed to the transmission delay, e.g., packet priority, its length, the user load, the processor load, the use of priority preemption, the use of preemption at packet reception, the number of processors, the number of protocol processing layers, the speed of each processor, and queue length limitations. Currently existing medium access queueing models are extended by adding modeling techniques which will handle exhaustive limited service both with and without priority traffic, and modeling capabilities are extended into the upper layers of the OSI model. Some of the model are parameterized solution methods, since it is shown that certain models do not exist as parameterized solutions, but rather as solution methods.

  12. Evaluation of concurrent priority queue algorithms. Technical report

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Huang, Q.

    1991-02-01

    The priority queue is a fundamental data structure that is used in a large variety of parallel algorithms, such as multiprocessor scheduling and parallel best-first search of state-space graphs. This thesis addresses the design and experimental evaluation of two novel concurrent priority queues: a parallel Fibonacci heap and a concurrent priority pool, and compares them with the concurrent binary heap. The parallel Fibonacci heap is based on the sequential Fibonacci heap, which is theoretically the most efficient data structure for sequential priority queues. This scheme not only preserves the efficient operation time bounds of its sequential counterpart, but also hasmore » very low contention by distributing locks over the entire data structure. The experimental results show its linearly scalable throughput and speedup up to as many processors as tested (currently 18). A concurrent access scheme for a doubly linked list is described as part of the implementation of the parallel Fibonacci heap. The concurrent priority pool is based on the concurrent B-tree and the concurrent pool. The concurrent priority pool has the highest throughput among the priority queues studied. Like the parallel Fibonacci heap, the concurrent priority pool scales linearly up to as many processors as tested. The priority queues are evaluated in terms of throughput and speedup. Some applications of concurrent priority queues such as the vertex cover problem and the single source shortest path problem are tested.« less

  13. Accelerating list management for MPI.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hemmert, K. Scott; Rodrigues, Arun F.; Underwood, Keith Douglas

    2005-07-01

    The latency and throughput of MPI messages are critically important to a range of parallel scientific applications. In many modern networks, both of these performance characteristics are largely driven by the performance of a processor on the network interface. Because of the semantics of MPI, this embedded processor is forced to traverse a linked list of posted receives each time a message is received. As this list grows long, the latency of message reception grows and the throughput of MPI messages decreases. This paper presents a novel hardware feature to handle list management functions on a network interface. By movingmore » functions such as list insertion, list traversal, and list deletion to the hardware unit, latencies are decreased by up to 20% in the zero length queue case with dramatic improvements in the presence of long queues. Similarly, the throughput is increased by up to 10% in the zero length queue case and by nearly 100% in the presence queues of 30 messages.« less

  14. Performance Modeling of the ADA Rendezvous

    DTIC Science & Technology

    1991-10-01

    queueing network of figure 2, SERVERTASK can complete only one rendezvous at a time. Thus, the rate that the rendezvous requests are processed at the... Network 1, SERVERTASK competes with the traffic tasks of Server Processor. Each time SERVERTASK gains access to the processor, SERVERTASK completes...Client Processor Server Processor Software Server Nek Netork2 Figure 10. A conceptualization of the algorithm. The SERVERTASK software server of Network 2

  15. Application of queueing models to multiprogrammed computer systems operating in a time-critical environment

    NASA Technical Reports Server (NTRS)

    Eckhardt, D. E., Jr.

    1979-01-01

    A model of a central processor (CPU) which services background applications in the presence of time critical activity is presented. The CPU is viewed as an M/M/1 queueing system subject to periodic interrupts by deterministic, time critical process. The Laplace transform of the distribution of service times for the background applications is developed. The use of state of the art queueing models for studying the background processing capability of time critical computer systems is discussed and the results of a model validation study which support this application of queueing models are presented.

  16. A Queue Simulation Tool for a High Performance Scientific Computing Center

    NASA Technical Reports Server (NTRS)

    Spear, Carrie; McGalliard, James

    2007-01-01

    The NASA Center for Computational Sciences (NCCS) at the Goddard Space Flight Center provides high performance highly parallel processors, mass storage, and supporting infrastructure to a community of computational Earth and space scientists. Long running (days) and highly parallel (hundreds of CPUs) jobs are common in the workload. NCCS management structures batch queues and allocates resources to optimize system use and prioritize workloads. NCCS technical staff use a locally developed discrete event simulation tool to model the impacts of evolving workloads, potential system upgrades, alternative queue structures and resource allocation policies.

  17. System Level RBDO for Military Ground Vehicles using High Performance Computing

    DTIC Science & Technology

    2008-01-01

    platform. Only the analyses that required more than 24 processors were conducted on the Onyx 350 due to the limited number of processors on the...optimization constraints varied. The queues set the number of processors and number of finite element code licenses available to the analyses. sgi ONYX ...3900: unix 24 MIPS R16000 PROCESSORS 4 IR2 GRAPHICS PIPES 4 IR3 GRAPHICS PIPES 24 GBYTES MEMORY 36 GBYTES LOCAL DISK SPACE sgi ONYX 350: unix 32 MIPS

  18. Parallel integer sorting with medium and fine-scale parallelism

    NASA Technical Reports Server (NTRS)

    Dagum, Leonardo

    1993-01-01

    Two new parallel integer sorting algorithms, queue-sort and barrel-sort, are presented and analyzed in detail. These algorithms do not have optimal parallel complexity, yet they show very good performance in practice. Queue-sort designed for fine-scale parallel architectures which allow the queueing of multiple messages to the same destination. Barrel-sort is designed for medium-scale parallel architectures with a high message passing overhead. The performance results from the implementation of queue-sort on a Connection Machine CM-2 and barrel-sort on a 128 processor iPSC/860 are given. The two implementations are found to be comparable in performance but not as good as a fully vectorized bucket sort on the Cray YMP.

  19. Marionette

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sullivan, M.; Anderson, D.P.

    1988-01-01

    Marionette is a system for distributed parallel programming in an environment of networked heterogeneous computer systems. It is based on a master/slave model. The master process can invoke worker operations (asynchronous remote procedure calls to single slaves) and context operations (updates to the state of all slaves). The master and slaves also interact through shared data structures that can be modified only by the master. The master and slave processes are programmed in a sequential language. The Marionette runtime system manages slave process creation, propagates shared data structures to slaves as needed, queues and dispatches worker and context operations, andmore » manages recovery from slave processor failures. The Marionette system also includes tools for automated compilation of program binaries for multiple architectures, and for distributing binaries to remote fuel systems. A UNIX-based implementation of Marionette is described.« less

  20. Why Are Drugs So Hard to Quit?

    MedlinePlus

    ... Loading... Close Yeah, keep it Undo Close This video is unavailable. Watch Queue Queue Watch Queue Queue ... in Share More Report Need to report the video? Sign in to report inappropriate content. Sign in ...

  1. Schedulers with load-store queue awareness

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Tong; Eichenberger, Alexandre E.; Jacob, Arpith C.

    2017-02-07

    In one embodiment, a computer-implemented method includes tracking a size of a load-store queue (LSQ) during compile time of a program. The size of the LSQ is time-varying and indicates how many memory access instructions of the program are on the LSQ. The method further includes scheduling, by a computer processor, a plurality of memory access instructions of the program based on the size of the LSQ.

  2. Schedulers with load-store queue awareness

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Tong; Eichenberger, Alexandre E.; Jacob, Arpith C.

    2017-01-24

    In one embodiment, a computer-implemented method includes tracking a size of a load-store queue (LSQ) during compile time of a program. The size of the LSQ is time-varying and indicates how many memory access instructions of the program are on the LSQ. The method further includes scheduling, by a computer processor, a plurality of memory access instructions of the program based on the size of the LSQ.

  3. Generalized Monitoring Facility. Users Manual.

    DTIC Science & Technology

    1982-05-01

    based monitor. The RMC will sample system queues and tables on a 30-second time interval. The data captured from these queues and cells are written...period, only the final change will be reported. The following communication region cells are constantly monitored for changes, since a processor...is reported as zeros in WW6.4. When GMC terminates, it writes a record containing information read from communication region cells and information

  4. Combining multi-layered bitmap files using network specific hardware

    DOEpatents

    DuBois, David H [Los Alamos, NM; DuBois, Andrew J [Santa Fe, NM; Davenport, Carolyn Connor [Los Alamos, NM

    2012-02-28

    Images and video can be produced by compositing or alpha blending a group of image layers or video layers. Increasing resolution or the number of layers results in increased computational demands. As such, the available computational resources limit the images and videos that can be produced. A computational architecture in which the image layers are packetized and streamed through processors can be easily scaled so to handle many image layers and high resolutions. The image layers are packetized to produce packet streams. The packets in the streams are received, placed in queues, and processed. For alpha blending, ingress queues receive the packetized image layers which are then z sorted and sent to egress queues. The egress queue packets are alpha blended to produce an output image or video.

  5. Multi-processor including data flow accelerator module

    DOEpatents

    Davidson, George S.; Pierce, Paul E.

    1990-01-01

    An accelerator module for a data flow computer includes an intelligent memory. The module is added to a multiprocessor arrangement and uses a shared tagged memory architecture in the data flow computer. The intelligent memory module assigns locations for holding data values in correspondence with arcs leading to a node in a data dependency graph. Each primitive computation is associated with a corresponding memory cell, including a number of slots for operands needed to execute a primitive computation, a primitive identifying pointer, and linking slots for distributing the result of the cell computation to other cells requiring that result as an operand. Circuitry is provided for utilizing tag bits to determine automatically when all operands required by a processor are available and for scheduling the primitive for execution in a queue. Each memory cell of the module may be associated with any of the primitives, and the particular primitive to be executed by the processor associated with the cell is identified by providing an index, such as the cell number for the primitive, to the primitive lookup table of starting addresses. The module thus serves to perform functions previously performed by a number of sections of data flow architectures and coexists with conventional shared memory therein. A multiprocessing system including the module operates in a hybrid mode, wherein the same processing modules are used to perform some processing in a sequential mode, under immediate control of an operating system, while performing other processing in a data flow mode.

  6. Design and Analysis of Scheduling Policies for Real-Time Computer Systems

    DTIC Science & Technology

    1992-01-01

    C. M. Krishna, "The Impact of Workload on the Reliability of Real-Time Processor Triads," to appear in Micro . Rel. [17] J.F. Kurose, "Performance... Processor Triads", to appear in Micro . Rel. "* J.F. Kurose. "Performance Analysis of Minimum Laxity Scheduling in Discrete Time Queue- ing Systems", to...exponentially distributed service times and deadlines. A similar model was developed for the ED policy for a single processor system under identical

  7. Analysis of the packet formation process in packet-switched networks

    NASA Astrophysics Data System (ADS)

    Meditch, J. S.

    Two new queueing system models for the packet formation process in packet-switched telecommunication networks are developed, and their applications in process stability, performance analysis, and optimization studies are illustrated. The first, an M/M/1 queueing system characterization of the process, is a highly aggregated model which is useful for preliminary studies. The second, a marked extension of an earlier M/G/1 model, permits one to investigate stability, performance characteristics, and design of the packet formation process in terms of the details of processor architecture, and hardware and software implementations with processor structure and as many parameters as desired as variables. The two new models together with the earlier M/G/1 characterization span the spectrum of modeling complexity for the packet formation process from basic to advanced.

  8. Specifications of a Simulation Model for a Local Area Network Design in Support of Stock Point Logistics Integrated Communications Environment (SPLICE).

    DTIC Science & Technology

    1982-10-01

    class queueing system with a preemptive -resume priority service discipline, as depicted in Figure 4.2. Concerning a SPLICLAN configuration a node can...processor can be modeled as a single resource, multi-class queueing system with a preemptive -resume priority structure as the one given in Figure 4.2. An...LOCAL AREA NETWORK DESIGN IN SUPPORT OF STOCK POINT LOGISTICS INTEGRATED COMMUNICATIONS ENVIRONMENT (SPLICE) by Ioannis Th. Mastrocostopoulos October

  9. Using Queue Time Predictions for Processor Allocation

    DTIC Science & Technology

    1997-01-01

    Diego Supercomputer Center, 1996. 19 [15] Vijay K. Naik, Sanjeev K. Setia , and Mark S. Squillante. Performance analysis of job schedul- ing policies in...Processing, pages 101{111, 1995. [19] Sanjeev K. Setia and Satish K. Tripathi. An analysis of several processor partitioning policies for parallel...computers. Technical Report CS-TR-2684, University of Maryland, May 1991. [20] Sanjeev K. Setia and Satish K. Tripathi. A comparative analysis of static

  10. Running ATLAS workloads within massively parallel distributed applications using Athena Multi-Process framework (AthenaMP)

    NASA Astrophysics Data System (ADS)

    Calafiura, Paolo; Leggett, Charles; Seuster, Rolf; Tsulaia, Vakhtang; Van Gemmeren, Peter

    2015-12-01

    AthenaMP is a multi-process version of the ATLAS reconstruction, simulation and data analysis framework Athena. By leveraging Linux fork and copy-on-write mechanisms, it allows for sharing of memory pages between event processors running on the same compute node with little to no change in the application code. Originally targeted to optimize the memory footprint of reconstruction jobs, AthenaMP has demonstrated that it can reduce the memory usage of certain configurations of ATLAS production jobs by a factor of 2. AthenaMP has also evolved to become the parallel event-processing core of the recently developed ATLAS infrastructure for fine-grained event processing (Event Service) which allows the running of AthenaMP inside massively parallel distributed applications on hundreds of compute nodes simultaneously. We present the architecture of AthenaMP, various strategies implemented by AthenaMP for scheduling workload to worker processes (for example: Shared Event Queue and Shared Distributor of Event Tokens) and the usage of AthenaMP in the diversity of ATLAS event processing workloads on various computing resources: Grid, opportunistic resources and HPC.

  11. X-LUNA: Extending Free/Open Source Real Time Executive for On-Board Space Applications

    NASA Astrophysics Data System (ADS)

    Braga, P.; Henriques, L.; Zulianello, M.

    2008-08-01

    In this paper we present xLuna, a system based on the RTEMS [1] Real-Time Operating System that is able to run on demand a GNU/Linux Operating System [2] as RTEMS' lowest priority task. Linux runs in user-mode and in a different memory partition. This allows running Hard Real-Time tasks and Linux applications on the same system sharing the Hardware resources while keeping a safe isolation and the Real-Time characteristics of RTEMS. Communication between both Systems is possible through a loose coupled mechanism based on message queues. Currently only SPARC LEON2 processor with Memory Management Unit (MMU) is supported. The advantage in having two isolated systems is that non critical components are quickly developed or simply ported reducing time-to-market and budget.

  12. Request queues for interactive clients in a shared file system of a parallel computing system

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bent, John M.; Faibish, Sorin

    Interactive requests are processed from users of log-in nodes. A metadata server node is provided for use in a file system shared by one or more interactive nodes and one or more batch nodes. The interactive nodes comprise interactive clients to execute interactive tasks and the batch nodes execute batch jobs for one or more batch clients. The metadata server node comprises a virtual machine monitor; an interactive client proxy to store metadata requests from the interactive clients in an interactive client queue; a batch client proxy to store metadata requests from the batch clients in a batch client queue;more » and a metadata server to store the metadata requests from the interactive client queue and the batch client queue in a metadata queue based on an allocation of resources by the virtual machine monitor. The metadata requests can be prioritized, for example, based on one or more of a predefined policy and predefined rules.« less

  13. NCC Simulation Model: Simulating the operations of the network control center, phase 2

    NASA Technical Reports Server (NTRS)

    Benjamin, Norman M.; Paul, Arthur S.; Gill, Tepper L.

    1992-01-01

    The simulation of the network control center (NCC) is in the second phase of development. This phase seeks to further develop the work performed in phase one. Phase one concentrated on the computer systems and interconnecting network. The focus of phase two will be the implementation of the network message dialogues and the resources controlled by the NCC. These resources are requested, initiated, monitored and analyzed via network messages. In the NCC network messages are presented in the form of packets that are routed across the network. These packets are generated, encoded, decoded and processed by the network host processors that generate and service the message traffic on the network that connects these hosts. As a result, the message traffic is used to characterize the work done by the NCC and the connected network. Phase one of the model development represented the NCC as a network of bi-directional single server queues and message generating sources. The generators represented the external segment processors. The served based queues represented the host processors. The NCC model consists of the internal and external processors which generate message traffic on the network that links these hosts. To fully realize the objective of phase two it is necessary to identify and model the processes in each internal processor. These processes live in the operating system of the internal host computers and handle tasks such as high speed message exchanging, ISN and NFE interface, event monitoring, network monitoring, and message logging. Inter process communication is achieved through the operating system facilities. The overall performance of the host is determined by its ability to service messages generated by both internal and external processors.

  14. Two Echelon Supply Chain Integrated Inventory Model for Similar Products: A Case Study

    NASA Astrophysics Data System (ADS)

    Parjane, Manoj Baburao; Dabade, Balaji Marutirao; Gulve, Milind Bhaskar

    2017-06-01

    The purpose of this paper is to develop a mathematical model towards minimization of total cost across echelons in a multi-product supply chain environment. The scenario under consideration is a two-echelon supply chain system with one manufacturer, one retailer and M products. The retailer faces independent Poisson demand for each product. The retailer and the manufacturer are closely coupled in the sense that the information about any depletion in the inventory of a product at a retailer's end is immediately available to the manufacturer. Further, stock-out is backordered at the retailer's end. Thus the costs incurred at the retailer's end are the holding costs and the backorder costs. The manufacturer has only one processor which is time shared among the M products. Production changeover from one product to another entails a fixed setup cost and a fixed set up time. Each unit of a product has a production time. Considering the cost components, and assuming transportation time and cost to be negligible, the objective of the study is to minimize the expected total cost considering both the manufacturer and retailer. In the process two aspects are to be defined. Firstly, every time a product is taken up for production, how much of it (production batch size, q) should be produced. Considering a large value of q favors the manufacturer while a small value of q suits the retailers. Secondly, for a given batch size q, at what level of retailer's inventory (production queuing point), the batch size S of a product be taken up for production by the manufacturer. A higher value of S incurs more holding cost whereas a lower value of S increases the chance of backorder. A tradeoff between the holding and backorder cost must be taken into consideration while choosing an optimal value of S. It may be noted that due to multiple products and single processor, a product `taken' up for production may not get the processor immediately, and may have to wait in a queue. The `S' should factor in the probability of waiting time in the queue.

  15. A novel strategy for load balancing of distributed medical applications.

    PubMed

    Logeswaran, Rajasvaran; Chen, Li-Choo

    2012-04-01

    Current trends in medicine, specifically in the electronic handling of medical applications, ranging from digital imaging, paperless hospital administration and electronic medical records, telemedicine, to computer-aided diagnosis, creates a burden on the network. Distributed Service Architectures, such as Intelligent Network (IN), Telecommunication Information Networking Architecture (TINA) and Open Service Access (OSA), are able to meet this new challenge. Distribution enables computational tasks to be spread among multiple processors; hence, performance is an important issue. This paper proposes a novel approach in load balancing, the Random Sender Initiated Algorithm, for distribution of tasks among several nodes sharing the same computational object (CO) instances in Distributed Service Architectures. Simulations illustrate that the proposed algorithm produces better network performance than the benchmark load balancing algorithms-the Random Node Selection Algorithm and the Shortest Queue Algorithm, especially under medium and heavily loaded conditions.

  16. TIME SHARING WITH AN EXPLICIT PRIORITY QUEUING DISCIPLINE.

    DTIC Science & Technology

    exponentially distributed service times and an ordered priority queue. Each new arrival buys a position in this queue by offering a non-negative bribe to the...parameters is investigated through numerical examples. Finally, to maximize the expected revenue per unit time accruing from bribes , an optimization

  17. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Attinella, John E.; Davis, Kristan D.; Musselman, Roy G.

    Methods, apparatuses, and computer program products for servicing a globally broadcast interrupt signal in a multi-threaded computer comprising a plurality of processor threads. Embodiments include an interrupt controller indicating in a plurality of local interrupt status locations that a globally broadcast interrupt signal has been received by the interrupt controller. Embodiments also include a thread determining that a local interrupt status location corresponding to the thread indicates that the globally broadcast interrupt signal has been received by the interrupt controller. Embodiments also include the thread processing one or more entries in a global interrupt status bit queue based on whethermore » global interrupt status bits associated with the globally broadcast interrupt signal are locked. Each entry in the global interrupt status bit queue corresponds to a queued global interrupt.« less

  18. Optimal Service Capacities in a Competitive Multiple-Server Queueing Environment

    NASA Astrophysics Data System (ADS)

    Ching, Wai-Ki; Choi, Sin-Man; Huang, Min

    The study of economic behavior of service providers in a competition environment is an important and interesting research issue. A two-server queueing model has been proposed in Kalai et al. [11] for this purpose. Their model aims at studying the role and impact of service capacity in capturing larger market share so as to maximize the long-run expected profit. They formulate the problem as a two-person strategic game and analyze the equilibrium solutions. The main aim of this paper is to extend the results of the two-server queueing model in [11] to the case of multiple servers. We will only focus on the case when the queueing system is stable.

  19. Mobile Thread Task Manager

    NASA Technical Reports Server (NTRS)

    Clement, Bradley J.; Estlin, Tara A.; Bornstein, Benjamin J.

    2013-01-01

    The Mobile Thread Task Manager (MTTM) is being applied to parallelizing existing flight software to understand the benefits and to develop new techniques and architectural concepts for adapting software to multicore architectures. It allocates and load-balances tasks for a group of threads that migrate across processors to improve cache performance. In order to balance-load across threads, the MTTM augments a basic map-reduce strategy to draw jobs from a global queue. In a multicore processor, memory may be "homed" to the cache of a specific processor and must be accessed from that processor. The MTTB architecture wraps access to data with thread management to move threads to the home processor for that data so that the computation follows the data in an attempt to avoid L2 cache misses. Cache homing is also handled by a memory manager that translates identifiers to processor IDs where the data will be homed (according to rules defined by the user). The user can also specify the number of threads and processors separately, which is important for tuning performance for different patterns of computation and memory access. MTTM efficiently processes tasks in parallel on a multiprocessor computer. It also provides an interface to make it easier to adapt existing software to a multiprocessor environment.

  20. Servicing a globally broadcast interrupt signal in a multi-threaded computer

    DOEpatents

    Attinella, John E.; Davis, Kristan D.; Musselman, Roy G.; Satterfield, David L.

    2015-12-29

    Methods, apparatuses, and computer program products for servicing a globally broadcast interrupt signal in a multi-threaded computer comprising a plurality of processor threads. Embodiments include an interrupt controller indicating in a plurality of local interrupt status locations that a globally broadcast interrupt signal has been received by the interrupt controller. Embodiments also include a thread determining that a local interrupt status location corresponding to the thread indicates that the globally broadcast interrupt signal has been received by the interrupt controller. Embodiments also include the thread processing one or more entries in a global interrupt status bit queue based on whether global interrupt status bits associated with the globally broadcast interrupt signal are locked. Each entry in the global interrupt status bit queue corresponds to a queued global interrupt.

  1. Shared performance monitor in a multiprocessor system

    DOEpatents

    Chiu, George; Gara, Alan G; Salapura, Valentina

    2014-12-02

    A performance monitoring unit (PMU) and method for monitoring performance of events occurring in a multiprocessor system. The multiprocessor system comprises a plurality of processor devices units, each processor device for generating signals representing occurrences of events in the processor device, and, a single shared counter resource for performance monitoring. The performance monitor unit is shared by all processor cores in the multiprocessor system. The PMU is further programmed to monitor event signals issued from non-processor devices.

  2. Shared performance monitor in a multiprocessor system

    DOEpatents

    Chiu, George; Gara, Alan G.; Salapura, Valentina

    2012-07-24

    A performance monitoring unit (PMU) and method for monitoring performance of events occurring in a multiprocessor system. The multiprocessor system comprises a plurality of processor devices units, each processor device for generating signals representing occurrences of events in the processor device, and, a single shared counter resource for performance monitoring. The performance monitor unit is shared by all processor cores in the multiprocessor system. The PMU comprises: a plurality of performance counters each for counting signals representing occurrences of events from one or more the plurality of processor units in the multiprocessor system; and, a plurality of input devices for receiving the event signals from one or more processor devices of the plurality of processor units, the plurality of input devices programmable to select event signals for receipt by one or more of the plurality of performance counters for counting, wherein the PMU is shared between multiple processing units, or within a group of processors in the multiprocessing system. The PMU is further programmed to monitor event signals issued from non-processor devices.

  3. Track and mode controller (TMC): a software executive for a high-altitude pointing and tracking experiment

    NASA Astrophysics Data System (ADS)

    Michnovicz, Michael R.

    1997-06-01

    A real-time executive has been implemented to control a high altitude pointing and tracking experiment. The track and mode controller (TMC) implements a table driven design, in which the track mode logic for a tracking mission is defined within a state transition diagram (STD). THe STD is implemented as a state transition table in the TMC software. Status Events trigger the state transitions in the STD. Each state, as it is entered, causes a number of processes to be activated within the system. As these processes propagate through the system, the status of key processes are monitored by the TMC, allowing further transitions within the STD. This architecture is implemented in real-time, using the vxWorks operating system. VxWorks message queues allow communication of status events from the Event Monitor task to the STD task. Process commands are propagated to the rest of the system processors by means of the SCRAMNet shared memory network. The system mode logic contained in the STD will autonomously sequence in acquisition, tracking and pointing system through an entire engagement sequence, starting with target detection and ending with aimpoint maintenance. Simulation results and lab test results will be presented to verify the mode controller. In addition to implementing the system mode logic with the STD, the TMC can process prerecorded time sequences of commands required during startup operations. It can also process single commands from the system operator. In this paper, the author presents (1) an overview, in which he describes the TMC architecture, the relationship of an end-to-end simulation to the flight software and the laboratory testing environment, (2) implementation details, including information on the vxWorks message queues and the SCRAMNet shared memory network, (3) simulation results and lab test results which verify the mode controller, and (4) plans for the future, specifically as to how this executive will expedite transition to a fully functional system.

  4. 7 CFR 1435.310 - Sharing processors' allocations with producers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... CREDIT CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS SUGAR PROGRAM Flexible Marketing Allotments For Sugar § 1435.310 Sharing processors' allocations with producers. (a) Every sugar beet and sugarcane processor must provide CCC a certification that: (1) The processor...

  5. 7 CFR 1435.310 - Sharing processors' allocations with producers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... CREDIT CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS SUGAR PROGRAM Flexible Marketing Allotments For Sugar § 1435.310 Sharing processors' allocations with producers. (a) Every sugar beet and sugarcane processor must provide CCC a certification that: (1) The processor...

  6. 7 CFR 1435.310 - Sharing processors' allocations with producers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... CREDIT CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS SUGAR PROGRAM Flexible Marketing Allotments For Sugar § 1435.310 Sharing processors' allocations with producers. (a) Every sugar beet and sugarcane processor must provide CCC a certification that: (1) The processor...

  7. 7 CFR 1435.310 - Sharing processors' allocations with producers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... CREDIT CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS SUGAR PROGRAM Flexible Marketing Allotments For Sugar § 1435.310 Sharing processors' allocations with producers. (a) Every sugar beet and sugarcane processor must provide CCC a certification that: (1) The processor...

  8. 7 CFR 1435.310 - Sharing processors' allocations with producers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... CREDIT CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS SUGAR PROGRAM Flexible Marketing Allotments For Sugar § 1435.310 Sharing processors' allocations with producers. (a) Every sugar beet and sugarcane processor must provide CCC a certification that: (1) The processor...

  9. Job Scheduling Under the Portable Batch System

    NASA Technical Reports Server (NTRS)

    Henderson, Robert L.; Woodrow, Thomas S. (Technical Monitor)

    1995-01-01

    The typical batch queuing system schedules jobs for execution by a set of queue controls. The controls determine from which queues jobs may be selected. Within the queue, jobs are ordered first-in, first-run. This limits the set of scheduling policies available to a site. The Portable Batch System removes this limitation by providing an external scheduling module. This separate program has full knowledge of the available queued jobs, running jobs, and system resource usage. Sites are able to implement any policy expressible in one of several procedural language. Policies may range from "bet fit" to "fair share" to purely political. Scheduling decisions can be made over the full set of jobs regardless of queue or order. The scheduling policy can be changed to fit a wide variety of computing environments and scheduling goals. This is demonstrated by the use of PBS on an IBM SP-2 system at NASA Ames.

  10. Store-operate-coherence-on-value

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Dong; Heidelberger, Philip; Kumar, Sameer

    A system, method and computer program product for performing various store-operate instructions in a parallel computing environment that includes a plurality of processors and at least one cache memory device. A queue in the system receives, from a processor, a store-operate instruction that specifies under which condition a cache coherence operation is to be invoked. A hardware unit in the system runs the received store-operate instruction. The hardware unit evaluates whether a result of the running the received store-operate instruction satisfies the condition. The hardware unit invokes a cache coherence operation on a cache memory address associated with the receivedmore » store-operate instruction if the result satisfies the condition. Otherwise, the hardware unit does not invoke the cache coherence operation on the cache memory device.« less

  11. A STUDY OF SOME SOFTWARE PARAMETERS IN TIME-SHARING SYSTEMS.

    DTIC Science & Technology

    A review is made of some existing time-sharing computer systems and an exploration of various software characteristics is conducted. This...of the various parameters upon the average response cycle time, the average number in the queue awaiting service , the average length of time a user is

  12. Communications systems and methods for subsea processors

    DOEpatents

    Gutierrez, Jose; Pereira, Luis

    2016-04-26

    A subsea processor may be located near the seabed of a drilling site and used to coordinate operations of underwater drilling components. The subsea processor may be enclosed in a single interchangeable unit that fits a receptor on an underwater drilling component, such as a blow-out preventer (BOP). The subsea processor may issue commands to control the BOP and receive measurements from sensors located throughout the BOP. A shared communications bus may interconnect the subsea processor and underwater components and the subsea processor and a surface or onshore network. The shared communications bus may be operated according to a time division multiple access (TDMA) scheme.

  13. Fast simulation of packet loss rates in a shared buffer communications switch

    NASA Technical Reports Server (NTRS)

    Chang, Cheng-Shang; Heidelberger, Philip; Shahabuddin, Perwez

    1993-01-01

    This paper describes an efficient technique for estimating, via simulation, the probability of buffer overflows in a queueing model that arises in the analysis of ATM (Asynchronous Transfer Mode) communication switches. There are multiple streams of (autocorrelated) traffic feeding the switch that has a buffer of finite capacity. Each stream is designated as either being of high or low priority. When the queue length reaches a certain threshold, only high priority packets are admitted to the switch's buffer. The problem is to estimate the loss rate of high priority packets. An asymptotically optimal importance sampling approach is developed for this rare event simulation problem. In this approach, the importance sampling is done in two distinct phases. In the first phase, an importance sampling change of measure is used to bring the queue length up to the threshold at which low priority packets get rejected. In the second phase, a different importance sampling change of measure is used to move the queue length from the threshold to the buffer capacity.

  14. Multiprocessor shared-memory information exchange

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Santoline, L.L.; Bowers, M.D.; Crew, A.W.

    1989-02-01

    In distributed microprocessor-based instrumentation and control systems, the inter-and intra-subsystem communication requirements ultimately form the basis for the overall system architecture. This paper describes a software protocol which addresses the intra-subsystem communications problem. Specifically the protocol allows for multiple processors to exchange information via a shared-memory interface. The authors primary goal is to provide a reliable means for information to be exchanged between central application processor boards (masters) and dedicated function processor boards (slaves) in a single computer chassis. The resultant Multiprocessor Shared-Memory Information Exchange (MSMIE) protocol, a standard master-slave shared-memory interface suitable for use in nuclear safety systems, ismore » designed to pass unidirectional buffers of information between the processors while providing a minimum, deterministic cycle time for this data exchange.« less

  15. Distributed processor allocation for launching applications in a massively connected processors complex

    DOEpatents

    Pedretti, Kevin

    2008-11-18

    A compute processor allocator architecture for allocating compute processors to run applications in a multiple processor computing apparatus is distributed among a subset of processors within the computing apparatus. Each processor of the subset includes a compute processor allocator. The compute processor allocators can share a common database of information pertinent to compute processor allocation. A communication path permits retrieval of information from the database independently of the compute processor allocators.

  16. PWFQ: a priority-based weighted fair queueing algorithm for the downstream transmission of EPON

    NASA Astrophysics Data System (ADS)

    Xu, Sunjuan; Ye, Jiajun; Zou, Junni

    2005-11-01

    In the downstream direction of EPON, all ethernet frames share one downlink channel from the OLT to destination ONUs. To guarantee differentiated services, a scheduling algorithm is needed to solve the link-sharing issue. In this paper, we first review the classical WFQ algorithm and point out the shortcomings existing in the fair queueing principle of WFQ algorithm for EPON. Then we propose a novel scheduling algorithm called Priority-based WFQ (PWFQ) algorithm which distributes bandwidth based on priority. PWFQ algorithm can guarantee the quality of real-time services whether under light load or under heavy load. Simulation results also show that PWFQ algorithm not only can improve delay performance of real-time services, but can also meet the worst-case delay bound requirements.

  17. Hypercluster - Parallel processing for computational mechanics

    NASA Technical Reports Server (NTRS)

    Blech, Richard A.

    1988-01-01

    An account is given of the development status, performance capabilities and implications for further development of NASA-Lewis' testbed 'hypercluster' parallel computer network, in which multiple processors communicate through a shared memory. Processors have local as well as shared memory; the hypercluster is expanded in the same manner as the hypercube, with processor clusters replacing the normal single processor node. The NASA-Lewis machine has three nodes with a vector personality and one node with a scalar personality. Each of the vector nodes uses four board-level vector processors, while the scalar node uses four general-purpose microcomputer boards.

  18. SAHAYOG: A Testbed for Load Sharing under Failure,

    DTIC Science & Technology

    1987-07-01

    messages, shared memory and semaphores . To communicate using messages, processes create message queues using system-provided prim- itives. The message...The size of the memory that is to be shared is decided by the process when it makes a request for memory allocation. The semaphore option of IPC can be...used to prevent two or more concurrent processes from executing their critical sections at the same time. Semaphores must be used when the processes

  19. Conditional load and store in a shared memory

    DOEpatents

    Blumrich, Matthias A; Ohmacht, Martin

    2015-02-03

    A method, system and computer program product for implementing load-reserve and store-conditional instructions in a multi-processor computing system. The computing system includes a multitude of processor units and a shared memory cache, and each of the processor units has access to the memory cache. In one embodiment, the method comprises providing the memory cache with a series of reservation registers, and storing in these registers addresses reserved in the memory cache for the processor units as a result of issuing load-reserve requests. In this embodiment, when one of the processor units makes a request to store data in the memory cache using a store-conditional request, the reservation registers are checked to determine if an address in the memory cache is reserved for that processor unit. If an address in the memory cache is reserved for that processor, the data are stored at this address.

  20. Occupational Feminization and Pay: Assessing Causal Dynamics Using 1950-2000 U.S. Census Data

    ERIC Educational Resources Information Center

    Levanon, Asaf; England, Paula; Allison, Paul

    2009-01-01

    Occupations with a greater share of females pay less than those with a lower share, controlling for education and skill. This association is explained by two dominant views: devaluation and queuing. The former views the pay offered in an occupation to affect its female proportion, due to employers' preference for men--a gendered labor queue. The…

  1. Kin competition within groups: the offspring depreciation hypothesis.

    PubMed Central

    Ridley, J; Sutherland, W J

    2002-01-01

    Where relatives compete for the same resources (kin competition) and each obtains an equal share, this can favour the evolution of elevated dispersal rates, such that most resource competition is among non-relatives. We show that this effect evaporates as among-sibling dominance increases to the point where the allocation of resources is maximally unequal. We restore a kin-competition effect on emigration rates from dominance-ranked family groups by showing that where siblings form queues to inherit the breeding positions, the length of the queue affects the fitness of all individuals by depreciating the rank of subsequent offspring. Incorporating this 'offspring depreciation' effect decreases optimal queue lengths, increases dispersal rates and explains the otherwise paradoxical use of sinks by cooperatively breeding birds in stable environments. The offspring depreciation effect also favours the evolution of small, but consistent, clutch sizes and high reproductive skew, but constrains the evolution of alloparenting. PMID:12573070

  2. Kin competition within groups: the offspring depreciation hypothesis.

    PubMed

    Ridley, J; Sutherland, W J

    2002-12-22

    Where relatives compete for the same resources (kin competition) and each obtains an equal share, this can favour the evolution of elevated dispersal rates, such that most resource competition is among non-relatives. We show that this effect evaporates as among-sibling dominance increases to the point where the allocation of resources is maximally unequal. We restore a kin-competition effect on emigration rates from dominance-ranked family groups by showing that where siblings form queues to inherit the breeding positions, the length of the queue affects the fitness of all individuals by depreciating the rank of subsequent offspring. Incorporating this 'offspring depreciation' effect decreases optimal queue lengths, increases dispersal rates and explains the otherwise paradoxical use of sinks by cooperatively breeding birds in stable environments. The offspring depreciation effect also favours the evolution of small, but consistent, clutch sizes and high reproductive skew, but constrains the evolution of alloparenting.

  3. vvtools v. 1.0

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Drake, Richard R.

    Vvtools is a suite of testing tools, with a focus on reproducible verification and validation. They are written in pure Python, and contain a test harness and an automated process management tool. Users of vvtools can develop suites of verification and validation tests and run them on small to large high performance computing resources in an automated and reproducible way. The test harness enables complex processes to be performed in each test and even supports a one-level parent/child dependency between tests. It includes a built in capability to manage workloads requiring multiple processors and platforms that use batch queueing systems.

  4. Method for prefetching non-contiguous data structures

    DOEpatents

    Blumrich, Matthias A [Ridgefield, CT; Chen, Dong [Croton On Hudson, NY; Coteus, Paul W [Yorktown Heights, NY; Gara, Alan G [Mount Kisco, NY; Giampapa, Mark E [Irvington, NY; Heidelberger, Philip [Cortlandt Manor, NY; Hoenicke, Dirk [Ossining, NY; Ohmacht, Martin [Brewster, NY; Steinmacher-Burow, Burkhard D [Mount Kisco, NY; Takken, Todd E [Mount Kisco, NY; Vranas, Pavlos M [Bedford Hills, NY

    2009-05-05

    A low latency memory system access is provided in association with a weakly-ordered multiprocessor system. Each processor in the multiprocessor shares resources, and each shared resource has an associated lock within a locking device that provides support for synchronization between the multiple processors in the multiprocessor and the orderly sharing of the resources. A processor only has permission to access a resource when it owns the lock associated with that resource, and an attempt by a processor to own a lock requires only a single load operation, rather than a traditional atomic load followed by store, such that the processor only performs a read operation and the hardware locking device performs a subsequent write operation rather than the processor. A simple perfecting for non-contiguous data structures is also disclosed. A memory line is redefined so that in addition to the normal physical memory data, every line includes a pointer that is large enough to point to any other line in the memory, wherein the pointers to determine which memory line to prefect rather than some other predictive algorithm. This enables hardware to effectively prefect memory access patterns that are non-contiguous, but repetitive.

  5. Decentralized Real-Time Scheduling

    DTIC Science & Technology

    1990-08-01

    must provide several alternative resource management policies, including FIFO and deadline queueing for shared resources that are not available. 5...When demand exceeds the supply of shared resources (even within a single switch), some calls cannot be completed. In that case, a call’s priority...associated chiefly with the need to manage resources in a timely and decentralized fashion. The Alpha programming model permits the convenient expression of

  6. On nonlinear finite element analysis in single-, multi- and parallel-processors

    NASA Technical Reports Server (NTRS)

    Utku, S.; Melosh, R.; Islam, M.; Salama, M.

    1982-01-01

    Numerical solution of nonlinear equilibrium problems of structures by means of Newton-Raphson type iterations is reviewed. Each step of the iteration is shown to correspond to the solution of a linear problem, therefore the feasibility of the finite element method for nonlinear analysis is established. Organization and flow of data for various types of digital computers, such as single-processor/single-level memory, single-processor/two-level-memory, vector-processor/two-level-memory, and parallel-processors, with and without sub-structuring (i.e. partitioning) are given. The effect of the relative costs of computation, memory and data transfer on substructuring is shown. The idea of assigning comparable size substructures to parallel processors is exploited. Under Cholesky type factorization schemes, the efficiency of parallel processing is shown to decrease due to the occasional shared data, just as that due to the shared facilities.

  7. Rapid recovery from transient faults in the fault-tolerant processor with fault-tolerant shared memory

    NASA Technical Reports Server (NTRS)

    Harper, Richard E.; Butler, Bryan P.

    1990-01-01

    The Draper fault-tolerant processor with fault-tolerant shared memory (FTP/FTSM), which is designed to allow application tasks to continue execution during the memory alignment process, is described. Processor performance is not affected by memory alignment. In addition, the FTP/FTSM incorporates a hardware scrubber device to perform the memory alignment quickly during unused memory access cycles. The FTP/FTSM architecture is described, followed by an estimate of the time required for channel reintegration.

  8. Architectures for reasoning in parallel

    NASA Technical Reports Server (NTRS)

    Hall, Lawrence O.

    1989-01-01

    The research conducted has dealt with rule-based expert systems. The algorithms that may lead to effective parallelization of them were investigated. Both the forward and backward chained control paradigms were investigated in the course of this work. The best computer architecture for the developed and investigated algorithms has been researched. Two experimental vehicles were developed to facilitate this research. They are Backpac, a parallel backward chained rule-based reasoning system and Datapac, a parallel forward chained rule-based reasoning system. Both systems have been written in Multilisp, a version of Lisp which contains the parallel construct, future. Applying the future function to a function causes the function to become a task parallel to the spawning task. Additionally, Backpac and Datapac have been run on several disparate parallel processors. The machines are an Encore Multimax with 10 processors, the Concert Multiprocessor with 64 processors, and a 32 processor BBN GP1000. Both the Concert and the GP1000 are switch-based machines. The Multimax has all its processors hung off a common bus. All are shared memory machines, but have different schemes for sharing the memory and different locales for the shared memory. The main results of the investigations come from experiments on the 10 processor Encore and the Concert with partitions of 32 or less processors. Additionally, experiments have been run with a stripped down version of EMYCIN.

  9. Efficient partitioning and assignment on programs for multiprocessor execution

    NASA Technical Reports Server (NTRS)

    Standley, Hilda M.

    1993-01-01

    The general problem studied is that of segmenting or partitioning programs for distribution across a multiprocessor system. Efficient partitioning and the assignment of program elements are of great importance since the time consumed in this overhead activity may easily dominate the computation, effectively eliminating any gains made by the use of the parallelism. In this study, the partitioning of sequentially structured programs (written in FORTRAN) is evaluated. Heuristics, developed for similar applications are examined. Finally, a model for queueing networks with finite queues is developed which may be used to analyze multiprocessor system architectures with a shared memory approach to the problem of partitioning. The properties of sequentially written programs form obstacles to large scale (at the procedure or subroutine level) parallelization. Data dependencies of even the minutest nature, reflecting the sequential development of the program, severely limit parallelism. The design of heuristic algorithms is tied to the experience gained in the parallel splitting. Parallelism obtained through the physical separation of data has seen some success, especially at the data element level. Data parallelism on a grander scale requires models that accurately reflect the effects of blocking caused by finite queues. A model for the approximation of the performance of finite queueing networks is developed. This model makes use of the decomposition approach combined with the efficiency of product form solutions.

  10. Fault-tolerant wait-free shared objects

    NASA Technical Reports Server (NTRS)

    Jayanti, Prasad; Chandra, Tushar D.; Toueg, Sam

    1992-01-01

    A concurrent system consists of processes communicating via shared objects, such as shared variables, queues, etc. The concept of wait-freedom was introduced to cope with process failures: each process that accesses a wait-free object is guaranteed to get a response even if all the other processes crash. However, if a wait-free object 'crashes,' all the processes that access that object are prevented from making progress. In this paper, we introduce the concept of fault-tolerant wait-free objects, and study the problem of implementing them. We give a universal method to construct fault-tolerant wait-free objects, for all types of 'responsive' failures (including one in which faulty objects may 'lie'). In sharp contrast, we prove that many common and interesting types (such as queues, sets, and test&set) have no fault-tolerant wait-free implementations even under the most benign of the 'non-responsive' types of failure. We also introduce several concepts and techniques that are central to the design of fault-tolerant concurrent systems: the concepts of self-implementation and graceful degradation, and techniques to automatically increase the fault-tolerance of implementations. We prove matching lower bounds on the resource complexity of most of our algorithms.

  11. Low latency memory access and synchronization

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Blumrich, Matthias A.; Chen, Dong; Coteus, Paul W.

    A low latency memory system access is provided in association with a weakly-ordered multiprocessor system. Each processor in the multiprocessor shares resources, and each shared resource has an associated lock within a locking device that provides support for synchronization between the multiple processors in the multiprocessor and the orderly sharing of the resources. A processor only has permission to access a resource when it owns the lock associated with that resource, and an attempt by a processor to own a lock requires only a single load operation, rather than a traditional atomic load followed by store, such that the processormore » only performs a read operation and the hardware locking device performs a subsequent write operation rather than the processor. A simple prefetching for non-contiguous data structures is also disclosed. A memory line is redefined so that in addition to the normal physical memory data, every line includes a pointer that is large enough to point to any other line in the memory, wherein the pointers to determine which memory line to prefetch rather than some other predictive algorithm. This enables hardware to effectively prefetch memory access patterns that are non-contiguous, but repetitive.« less

  12. Low latency memory access and synchronization

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Blumrich, Matthias A.; Chen, Dong; Coteus, Paul W.

    A low latency memory system access is provided in association with a weakly-ordered multiprocessor system. Bach processor in the multiprocessor shares resources, and each shared resource has an associated lock within a locking device that provides support for synchronization between the multiple processors in the multiprocessor and the orderly sharing of the resources. A processor only has permission to access a resource when it owns the lock associated with that resource, and an attempt by a processor to own a lock requires only a single load operation, rather than a traditional atomic load followed by store, such that the processormore » only performs a read operation and the hardware locking device performs a subsequent write operation rather than the processor. A simple prefetching for non-contiguous data structures is also disclosed. A memory line is redefined so that in addition to the normal physical memory data, every line includes a pointer that is large enough to point to any other line in the memory, wherein the pointers to determine which memory line to prefetch rather than some other predictive algorithm. This enables hardware to effectively prefetch memory access patterns that are non-contiguous, but repetitive.« less

  13. A message passing kernel for the hypercluster parallel processing test bed

    NASA Technical Reports Server (NTRS)

    Blech, Richard A.; Quealy, Angela; Cole, Gary L.

    1989-01-01

    A Message-Passing Kernel (MPK) for the Hypercluster parallel-processing test bed is described. The Hypercluster is being developed at the NASA Lewis Research Center to support investigations of parallel algorithms and architectures for computational fluid and structural mechanics applications. The Hypercluster resembles the hypercube architecture except that each node consists of multiple processors communicating through shared memory. The MPK efficiently routes information through the Hypercluster, using a message-passing protocol when necessary and faster shared-memory communication whenever possible. The MPK also interfaces all of the processors with the Hypercluster operating system (HYCLOPS), which runs on a Front-End Processor (FEP). This approach distributes many of the I/O tasks to the Hypercluster processors and eliminates the need for a separate I/O support program on the FEP.

  14. 50 CFR 680.40 - Crab Quota Share (QS), Processor QS (PQS), Individual Fishing Quota (IFQ), and Individual...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Crab Quota Share (QS), Processor QS (PQS... established based on the regional designations determined on August 1, 2005. QS or PQS issued after this date... information is true, correct, and complete to the best of his/her knowledge and belief. If the application is...

  15. Characterization of Stationary Distributions of Reflected Diffusions

    DTIC Science & Technology

    2014-01-01

    Reiman , M. I. (2003). Fluid and heavy traffic limits for a generalized processor sharing model. Ann. Appl. Probab., 13, 100-139. [37] Ramanan, K. and... Reiman , M. I. (2008). The heavy traffic limit of an unbalanced generalized processor sharing model. Ann. Appl. Probab., 18, 22-58. [38] Reed, J. and...Control and Computing. [39] Reiman , M. I. and Williams, R. J. (1988). A boundary property of semimartingale reflecting Brownian motions. Probab. Theor

  16. Parallelising a molecular dynamics algorithm on a multi-processor workstation

    NASA Astrophysics Data System (ADS)

    Müller-Plathe, Florian

    1990-12-01

    The Verlet neighbour-list algorithm is parallelised for a multi-processor Hewlett-Packard/Apollo DN10000 workstation. The implementation makes use of memory shared between the processors. It is a genuine master-slave approach by which most of the computational tasks are kept in the master process and the slaves are only called to do part of the nonbonded forces calculation. The implementation features elements of both fine-grain and coarse-grain parallelism. Apart from three calls to library routines, two of which are standard UNIX calls, and two machine-specific language extensions, the whole code is written in standard Fortran 77. Hence, it may be expected that this parallelisation concept can be transfered in parts or as a whole to other multi-processor shared-memory computers. The parallel code is routinely used in production work.

  17. Multiprocessing on supercomputers for computational aerodynamics

    NASA Technical Reports Server (NTRS)

    Yarrow, Maurice; Mehta, Unmeel B.

    1990-01-01

    Very little use is made of multiple processors available on current supercomputers (computers with a theoretical peak performance capability equal to 100 MFLOPs or more) in computational aerodynamics to significantly improve turnaround time. The productivity of a computer user is directly related to this turnaround time. In a time-sharing environment, the improvement in this speed is achieved when multiple processors are used efficiently to execute an algorithm. The concept of multiple instructions and multiple data (MIMD) through multi-tasking is applied via a strategy which requires relatively minor modifications to an existing code for a single processor. Essentially, this approach maps the available memory to multiple processors, exploiting the C-FORTRAN-Unix interface. The existing single processor code is mapped without the need for developing a new algorithm. The procedure for building a code utilizing this approach is automated with the Unix stream editor. As a demonstration of this approach, a Multiple Processor Multiple Grid (MPMG) code is developed. It is capable of using nine processors, and can be easily extended to a larger number of processors. This code solves the three-dimensional, Reynolds averaged, thin-layer and slender-layer Navier-Stokes equations with an implicit, approximately factored and diagonalized method. The solver is applied to generic oblique-wing aircraft problem on a four processor Cray-2 computer. A tricubic interpolation scheme is developed to increase the accuracy of coupling of overlapped grids. For the oblique-wing aircraft problem, a speedup of two in elapsed (turnaround) time is observed in a saturated time-sharing environment.

  18. Estimating Performance of Single Bus, Shared Memory Multiprocessors

    DTIC Science & Technology

    1987-05-01

    Chandy78] K.M. Chandy, C.M. Sauer, "Approximate methods for analyzing queuing network models of computing systems," Computing Surveys, vol10 , no 3...Denning78] P. Denning, J. Buzen, "The operational analysis of queueing network models", Computing Sur- veys, vol10 , no 3, September 1978, pp 225-261

  19. Vascular system modeling in parallel environment - distributed and shared memory approaches

    PubMed Central

    Jurczuk, Krzysztof; Kretowski, Marek; Bezy-Wendling, Johanne

    2011-01-01

    The paper presents two approaches in parallel modeling of vascular system development in internal organs. In the first approach, new parts of tissue are distributed among processors and each processor is responsible for perfusing its assigned parts of tissue to all vascular trees. Communication between processors is accomplished by passing messages and therefore this algorithm is perfectly suited for distributed memory architectures. The second approach is designed for shared memory machines. It parallelizes the perfusion process during which individual processing units perform calculations concerning different vascular trees. The experimental results, performed on a computing cluster and multi-core machines, show that both algorithms provide a significant speedup. PMID:21550891

  20. Error recovery in shared memory multiprocessors using private caches

    NASA Technical Reports Server (NTRS)

    Wu, Kun-Lung; Fuchs, W. Kent; Patel, Janak H.

    1990-01-01

    The problem of recovering from processor transient faults in shared memory multiprocesses systems is examined. A user-transparent checkpointing and recovery scheme using private caches is presented. Processes can recover from errors due to faulty processors by restarting from the checkpointed computation state. Implementation techniques using checkpoint identifiers and recovery stacks are examined as a means of reducing performance degradation in processor utilization during normal execution. This cache-based checkpointing technique prevents rollback propagation, provides rapid recovery, and can be integrated into standard cache coherence protocols. An analytical model is used to estimate the relative performance of the scheme during normal execution. Extensions to take error latency into account are presented.

  1. System and method for programmable bank selection for banked memory subsystems

    DOEpatents

    Blumrich, Matthias A.; Chen, Dong; Gara, Alan G.; Giampapa, Mark E.; Hoenicke, Dirk; Ohmacht, Martin; Salapura, Valentina; Sugavanam, Krishnan

    2010-09-07

    A programmable memory system and method for enabling one or more processor devices access to shared memory in a computing environment, the shared memory including one or more memory storage structures having addressable locations for storing data. The system comprises: one or more first logic devices associated with a respective one or more processor devices, each first logic device for receiving physical memory address signals and programmable for generating a respective memory storage structure select signal upon receipt of pre-determined address bit values at selected physical memory address bit locations; and, a second logic device responsive to each of the respective select signal for generating an address signal used for selecting a memory storage structure for processor access. The system thus enables each processor device of a computing environment memory storage access distributed across the one or more memory storage structures.

  2. Interconnect Performance Evaluation of SGI Altix 3700 BX2, Cray X1, Cray Opteron Cluster, and Dell PowerEdge

    NASA Technical Reports Server (NTRS)

    Fatoohi, Rod; Saini, Subbash; Ciotti, Robert

    2006-01-01

    We study the performance of inter-process communication on four high-speed multiprocessor systems using a set of communication benchmarks. The goal is to identify certain limiting factors and bottlenecks with the interconnect of these systems as well as to compare these interconnects. We measured network bandwidth using different number of communicating processors and communication patterns, such as point-to-point communication, collective communication, and dense communication patterns. The four platforms are: a 512-processor SGI Altix 3700 BX2 shared-memory machine with 3.2 GB/s links; a 64-processor (single-streaming) Cray XI shared-memory machine with 32 1.6 GB/s links; a 128-processor Cray Opteron cluster using a Myrinet network; and a 1280-node Dell PowerEdge cluster with an InfiniBand network. Our, results show the impact of the network bandwidth and topology on the overall performance of each interconnect.

  3. Solutions and debugging for data consistency in multiprocessors with noncoherent caches

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bernstein, D.; Mendelson, B.; Breternitz, M. Jr.

    1995-02-01

    We analyze two important problems that arise in shared-memory multiprocessor systems. The stale data problem involves ensuring that data items in local memory of individual processors are current, independent of writes done by other processors. False sharing occurs when two processors have copies of the same shared data block but update different portions of the block. The false sharing problem involves guaranteeing that subsequent writes are properly combined. In modern architectures these problems are usually solved in hardware, by exploiting mechanisms for hardware controlled cache consistency. This leads to more expensive and nonscalable designs. Therefore, we are concentrating on softwaremore » methods for ensuring cache consistency that would allow for affordable and scalable multiprocessing systems. Unfortunately, providing software control is nontrivial, both for the compiler writer and for the application programmer. For this reason we are developing a debugging environment that will facilitate the development of compiler-based techniques and will help the programmer to tune his or her application using explicit cache management mechanisms. We extend the notion of a race condition for IBM Shared Memory System POWER/4, taking into consideration its noncoherent caches, and propose techniques for detection of false sharing problems. Identification of the stale data problem is discussed as well, and solutions are suggested.« less

  4. Performance evaluation of throughput computing workloads using multi-core processors and graphics processors

    NASA Astrophysics Data System (ADS)

    Dave, Gaurav P.; Sureshkumar, N.; Blessy Trencia Lincy, S. S.

    2017-11-01

    Current trend in processor manufacturing focuses on multi-core architectures rather than increasing the clock speed for performance improvement. Graphic processors have become as commodity hardware for providing fast co-processing in computer systems. Developments in IoT, social networking web applications, big data created huge demand for data processing activities and such kind of throughput intensive applications inherently contains data level parallelism which is more suited for SIMD architecture based GPU. This paper reviews the architectural aspects of multi/many core processors and graphics processors. Different case studies are taken to compare performance of throughput computing applications using shared memory programming in OpenMP and CUDA API based programming.

  5. Stochastic Stability in Internet Router Congestion Games

    NASA Astrophysics Data System (ADS)

    Chung, Christine; Pyrga, Evangelia

    Congestion control at bottleneck routers on the internet is a long standing problem. Many policies have been proposed for effective ways to drop packets from the queues of these routers so that network endpoints will be inclined to share router capacity fairly and minimize the overflow of packets trying to enter the queues. We study just how effective some of these queuing policies are when each network endpoint is a self-interested player with no information about the other players’ actions or preferences. By employing the adaptive learning model of evolutionary game theory, we study policies such as Droptail, RED, and the greedy-flow-punishing policy proposed by Gao et al. [10] to find the stochastically stable states: the states of the system that will be reached in the long run.

  6. An efficient ASIC implementation of 16-channel on-line recursive ICA processor for real-time EEG system.

    PubMed

    Fang, Wai-Chi; Huang, Kuan-Ju; Chou, Chia-Ching; Chang, Jui-Chung; Cauwenberghs, Gert; Jung, Tzyy-Ping

    2014-01-01

    This is a proposal for an efficient very-large-scale integration (VLSI) design, 16-channel on-line recursive independent component analysis (ORICA) processor ASIC for real-time EEG system, implemented with TSMC 40 nm CMOS technology. ORICA is appropriate to be used in real-time EEG system to separate artifacts because of its highly efficient and real-time process features. The proposed ORICA processor is composed of an ORICA processing unit and a singular value decomposition (SVD) processing unit. Compared with previous work [1], this proposed ORICA processor has enhanced effectiveness and reduced hardware complexity by utilizing a deeper pipeline architecture, shared arithmetic processing unit, and shared registers. The 16-channel random signals which contain 8-channel super-Gaussian and 8-channel sub-Gaussian components are used to analyze the dependence of the source components, and the average correlation coefficient is 0.95452 between the original source signals and extracted ORICA signals. Finally, the proposed ORICA processor ASIC is implemented with TSMC 40 nm CMOS technology, and it consumes 15.72 mW at 100 MHz operating frequency.

  7. Concurrent array-based queue

    DOEpatents

    Heidelberger, Philip; Steinmacher-Burow, Burkhard

    2015-01-06

    According to one embodiment, a method for implementing an array-based queue in memory of a memory system that includes a controller includes configuring, in the memory, metadata of the array-based queue. The configuring comprises defining, in metadata, an array start location in the memory for the array-based queue, defining, in the metadata, an array size for the array-based queue, defining, in the metadata, a queue top for the array-based queue and defining, in the metadata, a queue bottom for the array-based queue. The method also includes the controller serving a request for an operation on the queue, the request providing the location in the memory of the metadata of the queue.

  8. The economics of time shared computing: Congestion, user costs and capacity

    NASA Technical Reports Server (NTRS)

    Agnew, C. E.

    1982-01-01

    Time shared systems permit the fixed costs of computing resources to be spread over large numbers of users. However, bottleneck results in the theory of closed queueing networks can be used to show that this economy of scale will be offset by the increased congestion that results as more users are added to the system. If one considers the total costs, including the congestion cost, there is an optimal number of users for a system which equals the saturation value usually used to define system capacity.

  9. Direct access inter-process shared memory

    DOEpatents

    Brightwell, Ronald B; Pedretti, Kevin; Hudson, Trammell B

    2013-10-22

    A technique for directly sharing physical memory between processes executing on processor cores is described. The technique includes loading a plurality of processes into the physical memory for execution on a corresponding plurality of processor cores sharing the physical memory. An address space is mapped to each of the processes by populating a first entry in a top level virtual address table for each of the processes. The address space of each of the processes is cross-mapped into each of the processes by populating one or more subsequent entries of the top level virtual address table with the first entry in the top level virtual address table from other processes.

  10. Data Interconnection Exploration

    NASA Technical Reports Server (NTRS)

    Iniguez, Alfredo Bravo

    2011-01-01

    This project involves innovating the way the Quality Assurance organization at the Jet Propulsion Laboratory (JPL) tracks the receiving inspection of JPL Critical Items (JCI) procured from suppliers. The Quality Assurance organization uses a Microsoft Access based front-end to enter items into an inspection queue. The current design has grown to be much more than was expected when the inspection queue system was created in 2007. The goal is to migrate to a web based solution that will allow the handling of more data, multiple input interfaces, and customizable display options. This has been achieved by implementing a divided tables scheme, the use of ColdFusion programming language, and the usage of Web 2.0 technologies such as AJAX and jQuery. These updates will allow for future expansion as well as the standardization of inspection queues for the Quality Assurance organization. When engineers and scientists order flight hardware, they cannot use it straight away. After a spacecraft or a satellite has been launched, it will be impossible to repair; therefore, the parts used must be inspected to make sure they are operating correctly and within the required specifications. The task of inspecting these JPL Critical Items (JCI) falls on the Quality Assurance organization. One of the tools the receiving inspection group uses is a database to maintain a queue of inspections that need to be done and of inspections that have been completed. The current Access interface has worked well but increased amounts of data, multiple input interfaces, and changes to how data is handled have made it necessary to seek a new way of organizing items for inspection. In addition, the different inspection groups have recently been merged and each has different ways of keeping track of inspection information. The ultimate goal is for the new group to have one shared inspection queue and website. To achieve this goal, I have been working with Ian Luczon of Procurement Quality Assurance and 3 Myers Hawkins, another intern, to not only create the new queue for receiving inspection but also a central web portal for the newly combined inspection group.

  11. High-performance computing — an overview

    NASA Astrophysics Data System (ADS)

    Marksteiner, Peter

    1996-08-01

    An overview of high-performance computing (HPC) is given. Different types of computer architectures used in HPC are discussed: vector supercomputers, high-performance RISC processors, various parallel computers like symmetric multiprocessors, workstation clusters, massively parallel processors. Software tools and programming techniques used in HPC are reviewed: vectorizing compilers, optimization and vector tuning, optimization for RISC processors; parallel programming techniques like shared-memory parallelism, message passing and data parallelism; and numerical libraries.

  12. An Adaptive Insertion and Promotion Policy for Partitioned Shared Caches

    NASA Astrophysics Data System (ADS)

    Mahrom, Norfadila; Liebelt, Michael; Raof, Rafikha Aliana A.; Daud, Shuhaizar; Hafizah Ghazali, Nur

    2018-03-01

    Cache replacement policies in chip multiprocessors (CMP) have been investigated extensively and proven able to enhance shared cache management. However, competition among multiple processors executing different threads that require simultaneous access to a shared memory may cause cache contention and memory coherence problems on the chip. These issues also exist due to some drawbacks of the commonly used Least Recently Used (LRU) policy employed in multiprocessor systems, which are because of the cache lines residing in the cache longer than required. In image processing analysis of for example extra pulmonary tuberculosis (TB), an accurate diagnosis for tissue specimen is required. Therefore, a fast and reliable shared memory management system to execute algorithms for processing vast amount of specimen image is needed. In this paper, the effects of the cache replacement policy in a partitioned shared cache are investigated. The goal is to quantify whether better performance can be achieved by using less complex replacement strategies. This paper proposes a Middle Insertion 2 Positions Promotion (MI2PP) policy to eliminate cache misses that could adversely affect the access patterns and the throughput of the processors in the system. The policy employs a static predefined insertion point, near distance promotion, and the concept of ownership in the eviction policy to effectively improve cache thrashing and to avoid resource stealing among the processors.

  13. Enhanced round robin CPU scheduling with burst time based time quantum

    NASA Astrophysics Data System (ADS)

    Indusree, J. R.; Prabadevi, B.

    2017-11-01

    Process scheduling is a very important functionality of Operating system. The main-known process-scheduling algorithms are First Come First Serve (FCFS) algorithm, Round Robin (RR) algorithm, Priority scheduling algorithm and Shortest Job First (SJF) algorithm. Compared to its peers, Round Robin (RR) algorithm has the advantage that it gives fair share of CPU to the processes which are already in the ready-queue. The effectiveness of the RR algorithm greatly depends on chosen time quantum value. Through this research paper, we are proposing an enhanced algorithm called Enhanced Round Robin with Burst-time based Time Quantum (ERRBTQ) process scheduling algorithm which calculates time quantum as per the burst-time of processes already in ready queue. The experimental results and analysis of ERRBTQ algorithm clearly indicates the improved performance when compared with conventional RR and its variants.

  14. A comparison of queueing, cluster and distributed computing systems

    NASA Technical Reports Server (NTRS)

    Kaplan, Joseph A.; Nelson, Michael L.

    1993-01-01

    Using workstation clusters for distributed computing has become popular with the proliferation of inexpensive, powerful workstations. Workstation clusters offer both a cost effective alternative to batch processing and an easy entry into parallel computing. However, a number of workstations on a network does not constitute a cluster. Cluster management software is necessary to harness the collective computing power. A variety of cluster management and queuing systems are compared: Distributed Queueing Systems (DQS), Condor, Load Leveler, Load Balancer, Load Sharing Facility (LSF - formerly Utopia), Distributed Job Manager (DJM), Computing in Distributed Networked Environments (CODINE), and NQS/Exec. The systems differ in their design philosophy and implementation. Based on published reports on the different systems and conversations with the system's developers and vendors, a comparison of the systems are made on the integral issues of clustered computing.

  15. Asynchronous Communication Scheme For Hypercube Computer

    NASA Technical Reports Server (NTRS)

    Madan, Herb S.

    1988-01-01

    Scheme devised for asynchronous-message communication system for Mark III hypercube concurrent-processor network. Network consists of up to 1,024 processing elements connected electrically as though were at corners of 10-dimensional cube. Each node contains two Motorola 68020 processors along with Motorola 68881 floating-point processor utilizing up to 4 megabytes of shared dynamic random-access memory. Scheme intended to support applications requiring passage of both polled or solicited and unsolicited messages.

  16. Tactical Operations Analysis Support Facility.

    DTIC Science & Technology

    1981-05-01

    Punch/Reader 2 DMC-11AR DDCMP Micro Processor 2 DMC-11DA Network Link Line Unit 2 DL-11E Async Serial Line Interface 4 Intel IN-1670 448K Words MOS Memory...86 5.3 VIRTUAL PROCESSORS - VAX-11/750 ........................... 89 5.4 A RELATIONAL DATA MANAGEMENT SYSTEM - ORACLE...Central Processing Unit (CPU) is a 16 bit processor for high-speed, real time applications, and for large multi-user, multi- task, time shared

  17. DMA shared byte counters in a parallel computer

    DOEpatents

    Chen, Dong; Gara, Alan G.; Heidelberger, Philip; Vranas, Pavlos

    2010-04-06

    A parallel computer system is constructed as a network of interconnected compute nodes. Each of the compute nodes includes at least one processor, a memory and a DMA engine. The DMA engine includes a processor interface for interfacing with the at least one processor, DMA logic, a memory interface for interfacing with the memory, a DMA network interface for interfacing with the network, injection and reception byte counters, injection and reception FIFO metadata, and status registers and control registers. The injection FIFOs maintain memory locations of the injection FIFO metadata memory locations including its current head and tail, and the reception FIFOs maintain the reception FIFO metadata memory locations including its current head and tail. The injection byte counters and reception byte counters may be shared between messages.

  18. Methodology for fast detection of false sharing in threaded scientific codes

    DOEpatents

    Chung, I-Hsin; Cong, Guojing; Murata, Hiroki; Negishi, Yasushi; Wen, Hui-Fang

    2014-11-25

    A profiling tool identifies a code region with a false sharing potential. A static analysis tool classifies variables and arrays in the identified code region. A mapping detection library correlates memory access instructions in the identified code region with variables and arrays in the identified code region while a processor is running the identified code region. The mapping detection library identifies one or more instructions at risk, in the identified code region, which are subject to an analysis by a false sharing detection library. A false sharing detection library performs a run-time analysis of the one or more instructions at risk while the processor is re-running the identified code region. The false sharing detection library determines, based on the performed run-time analysis, whether two different portions of the cache memory line are accessed by the generated binary code.

  19. Testing the Tester: Lessons Learned During the Testing of a State-of-the-Art Commercial 14nm Processor Under Proton Irradiation

    NASA Technical Reports Server (NTRS)

    Szabo, Carl M., Jr.; Duncan, Adam R.; Label, Kenneth A.

    2017-01-01

    Testing of an Intel 14nm desktop processor was conducted under proton irradiation. We share lessons learned, demonstrating that complex devices beget further complex challenges requiring practical and theoretical investigative expertise to solve.

  20. Applications considerations in the system design of highly concurrent multiprocessors

    NASA Technical Reports Server (NTRS)

    Lundstrom, Stephen F.

    1987-01-01

    A flow model processor approach to parallel processing is described, using very-high-performance individual processors, high-speed circuit switched interconnection networks, and a high-speed synchronization capability to minimize the effect of the inherently serial portions of applications on performance. Design studies related to the determination of the number of processors, the memory organization, and the structure of the networks used to interconnect the processor and memory resources are discussed. Simulations indicate that applications centered on the large shared data memory should be able to sustain over 500 million floating point operations per second.

  1. Reader set encoding for directory of shared cache memory in multiprocessor system

    DOEpatents

    Ahn, Dnaiel; Ceze, Luis H.; Gara, Alan; Ohmacht, Martin; Xiaotong, Zhuang

    2014-06-10

    In a parallel processing system with speculative execution, conflict checking occurs in a directory lookup of a cache memory that is shared by all processors. In each case, the same physical memory address will map to the same set of that cache, no matter which processor originated that access. The directory includes a dynamic reader set encoding, indicating what speculative threads have read a particular line. This reader set encoding is used in conflict checking. A bitset encoding is used to specify particular threads that have read the line.

  2. Cache-based error recovery for shared memory multiprocessor systems

    NASA Technical Reports Server (NTRS)

    Wu, Kun-Lung; Fuchs, W. Kent; Patel, Janak H.

    1989-01-01

    A multiprocessor cache-based checkpointing and recovery scheme for of recovering from transient processor errors in a shared-memory multiprocessor with private caches is presented. New implementation techniques that use checkpoint identifiers and recovery stacks to reduce performance degradation in processor utilization during normal execution are examined. This cache-based checkpointing technique prevents rollback propagation, provides for rapid recovery, and can be integrated into standard cache coherence protocols. An analytical model is used to estimate the relative performance of the scheme during normal execution. Extensions that take error latency into account are presented.

  3. Fault-Tolerant, Real-Time, Multi-Core Computer System

    NASA Technical Reports Server (NTRS)

    Gostelow, Kim P.

    2012-01-01

    A document discusses a fault-tolerant, self-aware, low-power, multi-core computer for space missions with thousands of simple cores, achieving speed through concurrency. The proposed machine decides how to achieve concurrency in real time, rather than depending on programmers. The driving features of the system are simple hardware that is modular in the extreme, with no shared memory, and software with significant runtime reorganizing capability. The document describes a mechanism for moving ongoing computations and data that is based on a functional model of execution. Because there is no shared memory, the processor connects to its neighbors through a high-speed data link. Messages are sent to a neighbor switch, which in turn forwards that message on to its neighbor until reaching the intended destination. Except for the neighbor connections, processors are isolated and independent of each other. The processors on the periphery also connect chip-to-chip, thus building up a large processor net. There is no particular topology to the larger net, as a function at each processor allows it to forward a message in the correct direction. Some chip-to-chip connections are not necessarily nearest neighbors, providing short cuts for some of the longer physical distances. The peripheral processors also provide the connections to sensors, actuators, radios, science instruments, and other devices with which the computer system interacts.

  4. Indirect addressing and load balancing for faster solution to Mandelbrot Set on SIMD architectures

    NASA Technical Reports Server (NTRS)

    Tomboulian, Sherryl

    1989-01-01

    SIMD computers with local indirect addressing allow programs to have queues and buffers, making certain kinds of problems much more efficient. Examined here are a class of problems characterized by computations on data points where the computation is identical, but the convergence rate is data dependent. Normally, in this situation, the algorithm time is governed by the maximum number of iterations required by each point. Using indirect addressing allows a processor to proceed to the next data point when it is done, reducing the overall number of iterations required to approach the mean convergence rate when a sufficiently large problem set is solved. Load balancing techniques can be applied for additional performance improvement. Simulations of this technique applied to solving Mandelbrot Sets indicate significant performance gains.

  5. Preventing messaging queue deadlocks in a DMA environment

    DOEpatents

    Blocksome, Michael A; Chen, Dong; Gooding, Thomas; Heidelberger, Philip; Parker, Jeff

    2014-01-14

    Embodiments of the invention may be used to manage message queues in a parallel computing environment to prevent message queue deadlock. A direct memory access controller of a compute node may determine when a messaging queue is full. In response, the DMA may generate and interrupt. An interrupt handler may stop the DMA and swap all descriptors from the full messaging queue into a larger queue (or enlarge the original queue). The interrupt handler then restarts the DMA. Alternatively, the interrupt handler stops the DMA, allocates a memory block to hold queue data, and then moves descriptors from the full messaging queue into the allocated memory block. The interrupt handler then restarts the DMA. During a normal messaging advance cycle, a messaging manager attempts to inject the descriptors in the memory block into other messaging queues until the descriptors have all been processed.

  6. PANDA: A distributed multiprocessor operating system

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chubb, P.

    1989-01-01

    PANDA is a design for a distributed multiprocessor and an operating system. PANDA is designed to allow easy expansion of both hardware and software. As such, the PANDA kernel provides only message passing and memory and process management. The other features needed for the system (device drivers, secondary storage management, etc.) are provided as replaceable user tasks. The thesis presents PANDA's design and implementation, both hardware and software. PANDA uses multiple 68010 processors sharing memory on a VME bus, each such node potentially connected to others via a high speed network. The machine is completely homogeneous: there are no differencesmore » between processors that are detectable by programs running on the machine. A single two-processor node has been constructed. Each processor contains memory management circuits designed to allow processors to share page tables safely. PANDA presents a programmers' model similar to the hardware model: a job is divided into multiple tasks, each having its own address space. Within each task, multiple processes share code and data. Tasks can send messages to each other, and set up virtual circuits between themselves. Peripheral devices such as disc drives are represented within PANDA by tasks. PANDA divides secondary storage into volumes, each volume being accessed by a volume access task, or VAT. All knowledge about the way that data is stored on a disc is kept in its volume's VAT. The design is such that PANDA should provide a useful testbed for file systems and device drivers, as these can be installed without recompiling PANDA itself, and without rebooting the machine.« less

  7. Message passing with queues and channels

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dozsa, Gabor J; Heidelberger, Philip; Kumar, Sameer

    In an embodiment, a reception thread receives a source node identifier, a type, and a data pointer from an application and, in response, creates a receive request. If the source node identifier specifies a source node, the reception thread adds the receive request to a fast-post queue. If a message received from a network does not match a receive request on a posted queue, a polling thread adds a receive request that represents the message to an unexpected queue. If the fast-post queue contains the receive request, the polling thread removes the receive request from the fast-post queue. If themore » receive request that was removed from the fast-post queue does not match the receive request on the unexpected queue, the polling thread adds the receive request that was removed from the fast-post queue to the posted queue. The reception thread and the polling thread execute asynchronously from each other.« less

  8. Increasing available FIFO space to prevent messaging queue deadlocks in a DMA environment

    DOEpatents

    Blocksome, Michael A [Rochester, MN; Chen, Dong [Croton On Hudson, NY; Gooding, Thomas [Rochester, MN; Heidelberger, Philip [Cortlandt Manor, NY; Parker, Jeff [Rochester, MN

    2012-02-07

    Embodiments of the invention may be used to manage message queues in a parallel computing environment to prevent message queue deadlock. A direct memory access controller of a compute node may determine when a messaging queue is full. In response, the DMA may generate an interrupt. An interrupt handler may stop the DMA and swap all descriptors from the full messaging queue into a larger queue (or enlarge the original queue). The interrupt handler then restarts the DMA. Alternatively, the interrupt handler stops the DMA, allocates a memory block to hold queue data, and then moves descriptors from the full messaging queue into the allocated memory block. The interrupt handler then restarts the DMA. During a normal messaging advance cycle, a messaging manager attempts to inject the descriptors in the memory block into other messaging queues until the descriptors have all been processed.

  9. Parallel ALLSPD-3D: Speeding Up Combustor Analysis Via Parallel Processing

    NASA Technical Reports Server (NTRS)

    Fricker, David M.

    1997-01-01

    The ALLSPD-3D Computational Fluid Dynamics code for reacting flow simulation was run on a set of benchmark test cases to determine its parallel efficiency. These test cases included non-reacting and reacting flow simulations with varying numbers of processors. Also, the tests explored the effects of scaling the simulation with the number of processors in addition to distributing a constant size problem over an increasing number of processors. The test cases were run on a cluster of IBM RS/6000 Model 590 workstations with ethernet and ATM networking plus a shared memory SGI Power Challenge L workstation. The results indicate that the network capabilities significantly influence the parallel efficiency, i.e., a shared memory machine is fastest and ATM networking provides acceptable performance. The limitations of ethernet greatly hamper the rapid calculation of flows using ALLSPD-3D.

  10. An experimental distributed microprocessor implementation with a shared memory communications and control medium

    NASA Technical Reports Server (NTRS)

    Mejzak, R. S.

    1980-01-01

    The distributed processing concept is defined in terms of control primitives, variables, and structures and their use in performing a decomposed discrete Fourier transform (DET) application function. The design assumes interprocessor communications to be anonymous. In this scheme, all processors can access an entire common database by employing control primitives. Access to selected areas within the common database is random, enforced by a hardware lock, and determined by task and subtask pointers. This enables the number of processors to be varied in the configuration without any modifications to the control structure. Decompositional elements of the DFT application function in terms of tasks and subtasks are also described. The experimental hardware configuration consists of IMSAI 8080 chassis which are independent, 8 bit microcomputer units. These chassis are linked together to form a multiple processing system by means of a shared memory facility. This facility consists of hardware which provides a bus structure to enable up to six microcomputers to be interconnected. It provides polling and arbitration logic so that only one processor has access to shared memory at any one time.

  11. Fault tolerant onboard packet switch architecture for communication satellites: Shared memory per beam approach

    NASA Technical Reports Server (NTRS)

    Shalkhauser, Mary JO; Quintana, Jorge A.; Soni, Nitin J.

    1994-01-01

    The NASA Lewis Research Center is developing a multichannel communication signal processing satellite (MCSPS) system which will provide low data rate, direct to user, commercial communications services. The focus of current space segment developments is a flexible, high-throughput, fault tolerant onboard information switching processor. This information switching processor (ISP) is a destination-directed packet switch which performs both space and time switching to route user information among numerous user ground terminals. Through both industry study contracts and in-house investigations, several packet switching architectures were examined. A contention-free approach, the shared memory per beam architecture, was selected for implementation. The shared memory per beam architecture, fault tolerance insertion, implementation, and demonstration plans are described.

  12. Computational performance of a smoothed particle hydrodynamics simulation for shared-memory parallel computing

    NASA Astrophysics Data System (ADS)

    Nishiura, Daisuke; Furuichi, Mikito; Sakaguchi, Hide

    2015-09-01

    The computational performance of a smoothed particle hydrodynamics (SPH) simulation is investigated for three types of current shared-memory parallel computer devices: many integrated core (MIC) processors, graphics processing units (GPUs), and multi-core CPUs. We are especially interested in efficient shared-memory allocation methods for each chipset, because the efficient data access patterns differ between compute unified device architecture (CUDA) programming for GPUs and OpenMP programming for MIC processors and multi-core CPUs. We first introduce several parallel implementation techniques for the SPH code, and then examine these on our target computer architectures to determine the most effective algorithms for each processor unit. In addition, we evaluate the effective computing performance and power efficiency of the SPH simulation on each architecture, as these are critical metrics for overall performance in a multi-device environment. In our benchmark test, the GPU is found to produce the best arithmetic performance as a standalone device unit, and gives the most efficient power consumption. The multi-core CPU obtains the most effective computing performance. The computational speed of the MIC processor on Xeon Phi approached that of two Xeon CPUs. This indicates that using MICs is an attractive choice for existing SPH codes on multi-core CPUs parallelized by OpenMP, as it gains computational acceleration without the need for significant changes to the source code.

  13. Competing for jobs: labor queues and gender sorting in the hiring process.

    PubMed

    Fernandez, Roberto M; Mors, Marie Louise

    2008-12-01

    While much research has documented the pattern and extent of sex segregation of workers once they are employed, few studies have addressed the pre-hire mechanisms that are posited to produce sex segregation in employment. While the notion of a labor queue-the rank order of the set of people that employers choose among-plays a prominent role in pre-hire accounts of job sex sorting mechanisms, few studies have examined the ways in which job candidates are sorted into labor queues. In this paper, we explore the mechanisms by which labor queues contribute to the gendering of jobs by studying the hiring process for all jobs at a call center. Being placed in a queue has a clear gendering effect on the hiring process: the sex distribution of applicants who are matched to queues and those who are rejected at this phase diverge, and among those assigned to queues, women are prevalent in queues for low pay, low status jobs. The screening process also contributes to the gendering of the population of hires at this firm. Females are more prevalent among hires than they are among candidates at initial queue assignment. Among high status jobs, however, males are more prevalent than females. Moreover, there are important wage implications associated with matching to queues. While there are large between-queue sex differences in the paid wages associated with allocation to queues, once allocated to queues the wage differences between male and female candidates are nil. Consequently, the roots of gender wage inequality in this setting lie in the initial sorting of candidates to labor queues.

  14. Computer architecture evaluation for structural dynamics computations: Project summary

    NASA Technical Reports Server (NTRS)

    Standley, Hilda M.

    1989-01-01

    The intent of the proposed effort is the examination of the impact of the elements of parallel architectures on the performance realized in a parallel computation. To this end, three major projects are developed: a language for the expression of high level parallelism, a statistical technique for the synthesis of multicomputer interconnection networks based upon performance prediction, and a queueing model for the analysis of shared memory hierarchies.

  15. Production Level CFD Code Acceleration for Hybrid Many-Core Architectures

    NASA Technical Reports Server (NTRS)

    Duffy, Austen C.; Hammond, Dana P.; Nielsen, Eric J.

    2012-01-01

    In this work, a novel graphics processing unit (GPU) distributed sharing model for hybrid many-core architectures is introduced and employed in the acceleration of a production-level computational fluid dynamics (CFD) code. The latest generation graphics hardware allows multiple processor cores to simultaneously share a single GPU through concurrent kernel execution. This feature has allowed the NASA FUN3D code to be accelerated in parallel with up to four processor cores sharing a single GPU. For codes to scale and fully use resources on these and the next generation machines, codes will need to employ some type of GPU sharing model, as presented in this work. Findings include the effects of GPU sharing on overall performance. A discussion of the inherent challenges that parallel unstructured CFD codes face in accelerator-based computing environments is included, with considerations for future generation architectures. This work was completed by the author in August 2010, and reflects the analysis and results of the time.

  16. Optimal processor assignment for pipeline computations

    NASA Technical Reports Server (NTRS)

    Nicol, David M.; Simha, Rahul; Choudhury, Alok N.; Narahari, Bhagirath

    1991-01-01

    The availability of large scale multitasked parallel architectures introduces the following processor assignment problem for pipelined computations. Given a set of tasks and their precedence constraints, along with their experimentally determined individual responses times for different processor sizes, find an assignment of processor to tasks. Two objectives are of interest: minimal response given a throughput requirement, and maximal throughput given a response time requirement. These assignment problems differ considerably from the classical mapping problem in which several tasks share a processor; instead, it is assumed that a large number of processors are to be assigned to a relatively small number of tasks. Efficient assignment algorithms were developed for different classes of task structures. For a p processor system and a series parallel precedence graph with n constituent tasks, an O(np2) algorithm is provided that finds the optimal assignment for the response time optimization problem; it was found that the assignment optimizing the constrained throughput in O(np2log p) time. Special cases of linear, independent, and tree graphs are also considered.

  17. The Completion of Non-Steady-State Queue Model on The Queue System in Dr. Yap Eye Hospital Yogyakarta

    NASA Astrophysics Data System (ADS)

    Helmi Manggala Putri, Arum; Subekti, Retno; Binatari, Nikenasih

    2017-06-01

    Dr Yap Eye Hospital Yogyakarta is one of the most popular reference eye hospitals in Yogyakarta. There are so many patients coming from other cities and many of them are BPJS (Badan Penyelenggara Jaminan Sosial, Social Security Administrative Bodies) patients. Therefore, it causes numerous BPJS patients were in long queue at counter C of the registration section so that it needs to be analysed using queue system. Queue system analysis aims to give queue model overview and determine its effectiveness measure. The data collecting technique used in this research are by interview and observation. After getting the arrival data and the service data of BPJS patients per 5 minutes, the next steps are investigating steady-state condition, examining the Poisson distribution, determining queue models, and counting the effectiveness measure. Based on the result of data observation on Tuesday, February 16th, 2016, it shows that the queue system at counter C has (M/M/1):(GD/∞/∞) queue model. The analysis result in counter C shows that the queue system is a non-steady-state condition. Three ways to cope a non-steady-state problem on queue system are proposed in this research such as bounding the capacity of queue system, adding the servers, and doing Monte Carlo simulation. The queue system in counter C will reach steady-state if the capacity of patients is not more than 52 BPJS patients or adding one more server. By using Monte Carlo simulation, it shows that the effectiveness measure of the average waiting time for BPJS patients in counter C is 36 minutes 65 seconds. In addition, the average queue length of BPJS patients is 11 patients.

  18. Android Protection Mechanism: A Signed Code Security Mechanism for Smartphone Applications

    DTIC Science & Technology

    2011-03-01

    status registers, exceptions, endian support, unaligned access support, synchronization primitives , the Jazelle Extension, and saturated integer...supports comprehensive non-blocking shared-memory synchronization primitives that scale for multiple-processor system designs. This is an improvement... synchronization . Memory semaphores can be loaded and altered without interruption because the load and store operations are atomic. Processor

  19. Do case-generic measures of queue performance for bypass surgery accurately reflect the waiting-list experiences of those most urgent?

    PubMed

    Burstein, Jason; Lee, Douglas S; Alter, David A

    2006-02-01

    Queue performance is typically assessed using generic measures, which capture the queue in aggregate. The objective of this study was to examine whether case-generic measures of queue performance appropriately reflected the waiting-list experiences of those patients with greatest disease severity. We examined the queue for isolated coronary artery bypass grafting (CABG) in Ontario between April 1993 and March 2000 using data obtained from the Cardiac Care Network. Our primary measure of queue performance was the proportion of patients who received their bypass surgery within their recommended maximum waiting times (%RMWTs) in any given month. We compared case-generic measures of queue performance to case-specific measures of queue performance stratified by urgency level. The queue was largely comprised of elective cases ranging from 73% (1993) to 57%(1999). Urgent patients comprised the minority of the queue ranging from 14% (1993) to 20% (1999). Case-generic month-to-month variations in the percentage of cases completed within RMWTs (an aggregated waiting list measure encompassing the characteristics of all patients in the queue) closely resembled the experiences of elective patients (R2 = 0.81), but conversely, bore little relationship to the waiting-list experiences of those most urgent (R2 = 0.15). Case-generic measures of queue performance for bypass surgery in Ontario were not reflective of the waiting-list experiences of those most urgent. Our results reinforce the concept that urgency-specific waiting list monitoring systems are required to best evaluate and appropriately respond to fluctuations in queue performance.

  20. The WorkQueue project - a task queue for the CMS workload management system

    NASA Astrophysics Data System (ADS)

    Ryu, S.; Wakefield, S.

    2012-12-01

    We present the development and first experience of a new component (termed WorkQueue) in the CMS workload management system. This component provides a link between a global request system (Request Manager) and agents (WMAgents) which process requests at compute and storage resources (known as sites). These requests typically consist of creation or processing of a data sample (possibly terabytes in size). Unlike the standard concept of a task queue, the WorkQueue does not contain fully resolved work units (known typically as jobs in HEP). This would require the WorkQueue to run computationally heavy algorithms that are better suited to run in the WMAgents. Instead the request specifies an algorithm that the WorkQueue uses to split the request into reasonable size chunks (known as elements). An advantage of performing lazy evaluation of an element is that expanding datasets can be accommodated by having job details resolved as late as possible. The WorkQueue architecture consists of a global WorkQueue which obtains requests from the request system, expands them and forms an element ordering based on the request priority. Each WMAgent contains a local WorkQueue which buffers work close to the agent, this overcomes temporary unavailability of the global WorkQueue and reduces latency for an agent to begin processing. Elements are pulled from the global WorkQueue to the local WorkQueue and into the WMAgent based on the estimate of the amount of work within the element and the resources available to the agent. WorkQueue is based on CouchDB, a document oriented NoSQL database. The WorkQueue uses the features of CouchDB (map/reduce views and bi-directional replication between distributed instances) to provide a scalable distributed system for managing large queues of work. The project described here represents an improvement over the old approach to workload management in CMS which involved individual operators feeding requests into agents. This new approach allows for a system where individual WMAgents are transient and can be added or removed from the system as needed.

  1. System and method for memory allocation in a multiclass memory system

    DOEpatents

    Loh, Gabriel; Meswani, Mitesh; Ignatowski, Michael; Nutter, Mark

    2016-06-28

    A system for memory allocation in a multiclass memory system includes a processor coupleable to a plurality of memories sharing a unified memory address space, and a library store to store a library of software functions. The processor identifies a type of a data structure in response to a memory allocation function call to the library for allocating memory to the data structure. Using the library, the processor allocates portions of the data structure among multiple memories of the multiclass memory system based on the type of the data structure.

  2. A High Performance VLSI Computer Architecture For Computer Graphics

    NASA Astrophysics Data System (ADS)

    Chin, Chi-Yuan; Lin, Wen-Tai

    1988-10-01

    A VLSI computer architecture, consisting of multiple processors, is presented in this paper to satisfy the modern computer graphics demands, e.g. high resolution, realistic animation, real-time display etc.. All processors share a global memory which are partitioned into multiple banks. Through a crossbar network, data from one memory bank can be broadcasted to many processors. Processors are physically interconnected through a hyper-crossbar network (a crossbar-like network). By programming the network, the topology of communication links among processors can be reconfigurated to satisfy specific dataflows of different applications. Each processor consists of a controller, arithmetic operators, local memory, a local crossbar network, and I/O ports to communicate with other processors, memory banks, and a system controller. Operations in each processor are characterized into two modes, i.e. object domain and space domain, to fully utilize the data-independency characteristics of graphics processing. Special graphics features such as 3D-to-2D conversion, shadow generation, texturing, and reflection, can be easily handled. With the current high density interconnection (MI) technology, it is feasible to implement a 64-processor system to achieve 2.5 billion operations per second, a performance needed in most advanced graphics applications.

  3. Data Telemetry and Acquisition System for Acoustic Signal Processing Investigations.

    DTIC Science & Technology

    1996-02-20

    were VME- based computer systems operating under the VxWorks real - time operating system . Each system shared a common hardware and software... real - time operating system . It interfaces to the Berg PCM Decommutator board, which searches for the embedded synchronization word in the data and re...software were built on top of this architecture. The multi-tasking, message queue and memory management facilities of the VxWorks real - time operating system are

  4. Best-First Heuristic Search for Multicore Machines

    DTIC Science & Technology

    2010-01-01

    Otto, 1998) to implement an asynchronous version of PRA* that they call Hash Distributed A* ( HDA *). HDA * distributes nodes using a hash function in...nodes which are being communicated between peers are in transit. In contact with the authors of HDA *, we have created an implementation of HDA * for...Also, our implementation of HDA * allows us to make a fair comparison between algorithms by sharing common data structures such as priority queues and

  5. Parallel processing on the Livermore VAX 11/780-4 parallel processor system with compatibility to Cray Research, Inc. (CRI) multitasking. Version 1

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Werner, N.E.; Van Matre, S.W.

    1985-05-01

    This manual describes the CRI Subroutine Library and Utility Package. The CRI library provides Cray multitasking functionality on the four-processor shared memory VAX 11/780-4. Additional functionality has been added for more flexibility. A discussion of the library, utilities, error messages, and example programs is provided.

  6. Online matching with queueing dynamics.

    DOT National Transportation Integrated Search

    2016-12-01

    We consider a variant of the multiarmed bandit problem where jobs queue for service, and service rates of different servers may be unknown. We study algorithms that minimize queue-regret: the (expected) difference between the queue-lengths obtained b...

  7. Field test implementation of queue control : final report.

    DOT National Transportation Integrated Search

    2011-12-01

    A major challenge for implementing queue control has been to accurately estimate on-ramp queue lengths, particularly during saturated onramp : conditions, when the vehicle queue extends around or beyond the ramp entrance. The main outcome of the rese...

  8. Queues with Choice via Delay Differential Equations

    NASA Astrophysics Data System (ADS)

    Pender, Jamol; Rand, Richard H.; Wesson, Elizabeth

    Delay or queue length information has the potential to influence the decision of a customer to join a queue. Thus, it is imperative for managers of queueing systems to understand how the information that they provide will affect the performance of the system. To this end, we construct and analyze two two-dimensional deterministic fluid models that incorporate customer choice behavior based on delayed queue length information. In the first fluid model, customers join each queue according to a Multinomial Logit Model, however, the queue length information the customer receives is delayed by a constant Δ. We show that the delay can cause oscillations or asynchronous behavior in the model based on the value of Δ. In the second model, customers receive information about the queue length through a moving average of the queue length. Although it has been shown empirically that giving patients moving average information causes oscillations and asynchronous behavior to occur in U.S. hospitals, we analytically and mathematically show for the first time that the moving average fluid model can exhibit oscillations and determine their dependence on the moving average window. Thus, our analysis provides new insight on how operators of service systems should report queue length information to customers and how delayed information can produce unwanted system dynamics.

  9. An enhanced Ada run-time system for real-time embedded processors

    NASA Technical Reports Server (NTRS)

    Sims, J. T.

    1991-01-01

    An enhanced Ada run-time system has been developed to support real-time embedded processor applications. The primary focus of this development effort has been on the tasking system and the memory management facilities of the run-time system. The tasking system has been extended to support efficient and precise periodic task execution as required for control applications. Event-driven task execution providing a means of task-asynchronous control and communication among Ada tasks is supported in this system. Inter-task control is even provided among tasks distributed on separate physical processors. The memory management system has been enhanced to provide object allocation and protected access support for memory shared between disjoint processors, each of which is executing a distinct Ada program.

  10. Generalized priority-queue network dynamics: Impact of team and hierarchy

    NASA Astrophysics Data System (ADS)

    Cho, Won-Kuk; Min, Byungjoon; Goh, K.-I.; Kim, I.-M.

    2010-06-01

    We study the effect of team and hierarchy on the waiting-time dynamics of priority-queue networks. To this end, we introduce generalized priority-queue network models incorporating interaction rules based on team-execution and hierarchy in decision making, respectively. It is numerically found that the waiting-time distribution exhibits a power law for long waiting times in both cases, yet with different exponents depending on the team size and the position of queue nodes in the hierarchy, respectively. The observed power-law behaviors have in many cases a corresponding single or pairwise-interacting queue dynamics, suggesting that the pairwise interaction may constitute a major dynamic consequence in the priority-queue networks. It is also found that the reciprocity of influence is a relevant factor for the priority-queue network dynamics.

  11. 7 CFR 1435.315 - Adjustments to proportionate shares.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS SUGAR PROGRAM Flexible Marketing Allotments For Sugar § 1435.315 Adjustments to proportionate shares. Whenever CCC determines that, because of... sufficient to enable state processors to produce sufficient sugar to meet the State's cane sugar allotment...

  12. 7 CFR 1435.315 - Adjustments to proportionate shares.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS SUGAR PROGRAM Flexible Marketing Allotments For Sugar § 1435.315 Adjustments to proportionate shares. Whenever CCC determines that, because of... sufficient to enable state processors to produce sufficient sugar to meet the State's cane sugar allotment...

  13. 7 CFR 1435.315 - Adjustments to proportionate shares.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS SUGAR PROGRAM Flexible Marketing Allotments For Sugar § 1435.315 Adjustments to proportionate shares. Whenever CCC determines that, because of... sufficient to enable state processors to produce sufficient sugar to meet the State's cane sugar allotment...

  14. 7 CFR 1435.315 - Adjustments to proportionate shares.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS SUGAR PROGRAM Flexible Marketing Allotments For Sugar § 1435.315 Adjustments to proportionate shares. Whenever CCC determines that, because of... sufficient to enable state processors to produce sufficient sugar to meet the State's cane sugar allotment...

  15. 7 CFR 1435.315 - Adjustments to proportionate shares.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS SUGAR PROGRAM Flexible Marketing Allotments For Sugar § 1435.315 Adjustments to proportionate shares. Whenever CCC determines that, because of... sufficient to enable state processors to produce sufficient sugar to meet the State's cane sugar allotment...

  16. Control of Entry to a Queueing System

    DTIC Science & Technology

    1979-11-01

    being devoted to the use of queueing theory to control ard optimize the o~peration i f a system. Here, queueing analyses are used to design a system...operpting costs below somae upper bound while maximizing throughput of the queue. This more recent approach of designing or controlling a queueing system...ports designated as high density traffic airports, the Federal Aviation Administration (FAA) limits the number of instrument flight r’ule (IFR

  17. Peregrine Queue Changes | High-Performance Computing | NREL

    Science.gov Websites

    that the best path is to disable the large queue and move the nodes from the "large" queue to jobs that request a large number of nodes. The large queue was disabled during the October System time

  18. The network queueing system

    NASA Technical Reports Server (NTRS)

    Kingsbury, Brent K.

    1986-01-01

    Described is the implementation of a networked, UNIX based queueing system developed on contract for NASA. The system discussed supports both batch and device requests, and provides the facilities of remote queueing, request routing, remote status, queue access controls, batch request resource quota limits, and remote output return.

  19. An analytical study of various telecomminication networks using markov models

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, M.; Jayamani, E.; Ezhumalai, P.

    2015-04-01

    The main aim of this paper is to examine issues relating to the performance of various Telecommunication networks, and applied queuing theory for better design and improved efficiency. Firstly, giving an analytical study of queues deals with quantifying the phenomenon of waiting lines using representative measures of performances, such as average queue length (on average number of customers in the queue), average waiting time in queue (on average time to wait) and average facility utilization (proportion of time the service facility is in use). In the second, using Matlab simulator, summarizes the finding of the investigations, from which and where we obtain results and describing methodology for a) compare the waiting time and average number of messages in the queue in M/M/1 and M/M/2 queues b) Compare the performance of M/M/1 and M/D/1 queues and study the effect of increasing the number of servers on the blocking probability M/M/k/k queue model.

  20. Data traffic reduction schemes for sparse Cholesky factorizations

    NASA Technical Reports Server (NTRS)

    Naik, Vijay K.; Patrick, Merrell L.

    1988-01-01

    Load distribution schemes are presented which minimize the total data traffic in the Cholesky factorization of dense and sparse, symmetric, positive definite matrices on multiprocessor systems with local and shared memory. The total data traffic in factoring an n x n sparse, symmetric, positive definite matrix representing an n-vertex regular 2-D grid graph using n (sup alpha), alpha is equal to or less than 1, processors are shown to be O(n(sup 1 + alpha/2)). It is O(n(sup 3/2)), when n (sup alpha), alpha is equal to or greater than 1, processors are used. Under the conditions of uniform load distribution, these results are shown to be asymptotically optimal. The schemes allow efficient use of up to O(n) processors before the total data traffic reaches the maximum value of O(n(sup 3/2)). The partitioning employed within the scheme, allows a better utilization of the data accessed from shared memory than those of previously published methods.

  1. Fast concurrent array-based stacks, queues and deques using fetch-and-increment-bounded, fetch-and-decrement-bounded and store-on-twin synchronization primitives

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Dong; Gara, Alana; Heidelberger, Philip

    Implementation primitives for concurrent array-based stacks, queues, double-ended queues (deques) and wrapped deques are provided. In one aspect, each element of the stack, queue, deque or wrapped deque data structure has its own ticket lock, allowing multiple threads to concurrently use multiple elements of the data structure and thus achieving high performance. In another aspect, new synchronization primitives FetchAndIncrementBounded (Counter, Bound) and FetchAndDecrementBounded (Counter, Bound) are implemented. These primitives can be implemented in hardware and thus promise a very fast throughput for queues, stacks and double-ended queues.

  2. Telemetry Standards, RCC Standard 106-17. Chapter 24. Message Formats

    DTIC Science & Technology

    2017-07-01

    strength indicator TCP Transmission Control Protocol TE Traffic Engineering TAI International Atomic Time TLV Type-Length-Value TmNS Telemetry...to a specific radio link. TE Queue Status Report 10 This TLV is used by a radio to report Traffic Engineering (TE) queue levels for each of the 8...24.3.2.6 Traffic Engineering Queue Status Report TLV The TE Queue Status Report TLV shall be used to report the queue levels of the eight

  3. Development of a Dynamic Time Sharing Scheduled Environment Final Report CRADA No. TC-824-94E

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jette, M.; Caliga, D.

    Massively parallel computers, such as the Cray T3D, have historically supported resource sharing solely with space sharing. In that method, multiple problems are solved by executing them on distinct processors. This project developed a dynamic time- and space-sharing scheduler to achieve greater interactivity and throughput than could be achieved with space-sharing alone. CRI and LLNL worked together on the design, testing, and review aspects of this project. There were separate software deliverables. CFU implemented a general purpose scheduling system as per the design specifications. LLNL ported the local gang scheduler software to the LLNL Cray T3D. In this approach, processorsmore » are allocated simultaneously to aU components of a parallel program (in a “gang”). Program execution is preempted as needed to provide for interactivity. Programs are also reIocated to different processors as needed to efficiently pack the computer’s torus of processors. In phase one, CRI developed an interface specification after discussions with LLNL for systemlevel software supporting a time- and space-sharing environment on the LLNL T3D. The two parties also discussed interface specifications for external control tools (such as scheduling policy tools, system administration tools) and applications programs. CRI assumed responsibility for the writing and implementation of all the necessary system software in this phase. In phase two, CRI implemented job-rolling on the Cray T3D, a mechanism for preempting a program, saving its state to disk, and later restoring its state to memory for continued execution. LLNL ported its gang scheduler to the LLNL T3D utilizing the CRI interface implemented in phases one and two. During phase three, the functionality and effectiveness of the LLNL gang scheduler was assessed to provide input to CRI time- and space-sharing, efforts. CRI will utilize this information in the development of general schedulers suitable for other sites and future architectures.« less

  4. Parallel processing approach to transform-based image coding

    NASA Astrophysics Data System (ADS)

    Normile, James O.; Wright, Dan; Chu, Ken; Yeh, Chia L.

    1991-06-01

    This paper describes a flexible parallel processing architecture designed for use in real time video processing. The system consists of floating point DSP processors connected to each other via fast serial links, each processor has access to a globally shared memory. A multiple bus architecture in combination with a dual ported memory allows communication with a host control processor. The system has been applied to prototyping of video compression and decompression algorithms. The decomposition of transform based algorithms for decompression into a form suitable for parallel processing is described. A technique for automatic load balancing among the processors is developed and discussed, results ar presented with image statistics and data rates. Finally techniques for accelerating the system throughput are analyzed and results from the application of one such modification described.

  5. Message passing with queues and channels

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dozsa, Gabor J; Heidelberger, Philip; Kumar, Sameer

    In an embodiment, a send thread receives an identifier that identifies a destination node and a pointer to data. The send thread creates a first send request in response to the receipt of the identifier and the data pointer. The send thread selects a selected channel from among a plurality of channels. The selected channel comprises a selected hand-off queue and an identification of a selected message unit. Each of the channels identifies a different message unit. The selected hand-off queue is randomly accessible. If the selected hand-off queue contains an available entry, the send thread adds the first sendmore » request to the selected hand-off queue. If the selected hand-off queue does not contain an available entry, the send thread removes a second send request from the selected hand-off queue and sends the second send request to the selected message unit.« less

  6. Analysis of bulk arrival queueing system with batch size dependent service and working vacation

    NASA Astrophysics Data System (ADS)

    Niranjan, S. P.; Indhira, K.; Chandrasekaran, V. M.

    2018-04-01

    This paper concentrates on single server bulk arrival queue system with batch size dependent service and working vacation. The server provides service in two service modes depending upon the queue length. The server provides single service if the queue length is at least `a'. On the other hand the server provides fixed batch service if the queue length is at least `k' (k > a). Batch service is provided with some fixed batch size `k'. After completion of service if the queue length is less than `a' then the server leaves for working vacation. During working vacation customers are served with lower service rate than the regular service rate. Service during working vacation also contains two service modes. For the proposed model probability generating function of the queue length at an arbitrary time will be obtained by using supplementary variable technique. Some performance measures will also be presented with suitable numerical illustrations.

  7. Transient queue-size distribution in a finite-capacity queueing system with server breakdowns and Bernoulli feedback

    NASA Astrophysics Data System (ADS)

    Kempa, Wojciech M.

    2017-12-01

    A finite-capacity queueing system with server breakdowns is investigated, in which successive exponentially distributed failure-free times are followed by repair periods. After the processing a customer may either rejoin the queue (feedback) with probability q, or definitely leave the system with probability 1 - q. The system of integral equations for transient queue-size distribution, conditioned by the initial level of buffer saturation, is build. The solution of the corresponding system written for Laplace transforms is found using the linear algebraic approach. The considered queueing system can be successfully used in modelling production lines with machine failures, in which the parameter q may be considered as a typical fraction of items demanding corrections. Morever, this queueing model can be applied in the analysis of real TCP/IP performance, where q stands for the fraction of packets requiring retransmission.

  8. Optimal routing and buffer allocation for a class of finite capacity queueing systems

    NASA Technical Reports Server (NTRS)

    Towsley, Don; Sparaggis, Panayotis D.; Cassandras, Christos G.

    1992-01-01

    The problem of routing jobs to K parallel queues with identical exponential servers and unequal finite buffer capacities is considered. Routing decisions are taken by a controller which has buffering space available to it and may delay routing of a customer to a queue. Using ideas from weak majorization, it is shown that the shorter nonfull queue delayed (SNQD) policy minimizes both the total number of customers in the system at any time and the number of customers that are rejected by that time. The SNQD policy always delays routing decisions as long as all servers are busy. Only when all the buffers at the controller are occupied is a customer routed to the queue with the shortest queue length that is not at capacity. Moreover, it is shown that, if a fixed number of buffers is to be distributed among the K queues, then the optimal allocation scheme is the one in which the difference between the maximum and minimum queue capacities is minimized, i.e., becomes either 0 or 1.

  9. Queueing system analysis of multi server model at XYZ insurance company in Tasikmalaya city

    NASA Astrophysics Data System (ADS)

    Muhajir, Ahmad; Binatari, Nikenasih

    2017-08-01

    Queueing theory or waiting line theory is a theory that deals with the queue process from the customer comes, queue to be served, served and left on service facilities. Queue occurs because of a mismatch between the numbers of customers that will be served with the available number of services, as an example at XYZ insurance company in Tasikmalaya. This research aims to determine the characteristics of the queue system which then to optimize the number of server in term of total cost. The result shows that the queue model can be represented by (M/M/4):(GD/∞/∞), where the arrivals are Poisson distributed while the service time is following exponential distribution. The probability of idle customer service is 2,39% of the working time, the average number of customer in the queue is 3 customers, the average number of customer in a system is 6 customers, the average time of a customer spent in the queue is 15,9979 minutes, the average time a customer spends in the system is 34,4141 minutes, and the average number of busy customer servicer is 3 server. The optimized number of customer service is 5 servers, and the operational cost has minimum cost at Rp 4.323.

  10. Waiting to see the doctor. The impact of organizational structure on medical practice.

    PubMed

    Wolinsky, F D; Marder, W D

    1983-05-01

    In this article it is assessed whether or not the scheduling and office visit queues a patient faces depend upon the organizational structure of the physician's practice (i.e., does the physician practice in the fee-for-service system or in a health maintenance organization [HMO], and if in an HMO, in what type of an HMO). Data pooled from two national studies (N = 2448) reveal two major findings. First, although scheduling queues may be predicted from the organizational structure of physicians' practices and other factors, office queues appear to be more of a random phenomenon. Second, a distinct pattern emerges among the effects of the organizational structure of physicians' practices on patient queues, including 1) physicians in solo practice offer their patients the shortest queues, 2) physicians in group model HMOs maximize scheduling queues but minimize waiting room queues, 3) patient queues for physicians practicing in IPAs are no different from those of their counterparts in group-practice fee-for-service settings, and 4) patient queues for salaried physicians practicing in a predominantly salaried environment are among the longest. The implications of these findings are discussed with special reference to extent and future studies of the effects of organizational structure on medical practice.

  11. Visualization Co-Processing of a CFD Simulation

    NASA Technical Reports Server (NTRS)

    Vaziri, Arsi

    1999-01-01

    OVERFLOW, a widely used CFD simulation code, is combined with a visualization system, pV3, to experiment with an environment for simulation/visualization co-processing on a SGI Origin 2000 computer(O2K) system. The shared memory version of the solver is used with the O2K 'pfa' preprocessor invoked to automatically discover parallelism in the source code. No other explicit parallelism is enabled. In order to study the scaling and performance of the visualization co-processing system, sample runs are made with different processor groups in the range of 1 to 254 processors. The data exchange between the visualization system and the simulation system is rapid enough for user interactivity when the problem size is small. This shared memory version of OVERFLOW, with minimal parallelization, does not scale well to an increasing number of available processors. The visualization task takes about 18 to 30% of the total processing time and does not appear to be a major contributor to the poor scaling. Improper load balancing and inter-processor communication overhead are contributors to this poor performance. Work is in progress which is aimed at obtaining improved parallel performance of the solver and removing the limitations of serial data transfer to pV3 by examining various parallelization/communication strategies, including the use of the explicit message passing.

  12. 76 FR 3090 - Proposed Information Collection; Comment Request; Alaska Region; Bering Sea and Aleutian Islands...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-19

    ... submitted on or before March 21, 2011. ADDRESSES: Direct all written comments to Diana Hynek, Departmental... fisheries. Program components include quota share allocation, processor quota share allocation, individual... Binding Arbitration process, and fee collection. II. Method of Collection Responses are mailed, except the...

  13. Queueing theoretic analysis of labor and delivery : Understanding management styles and C-section rates.

    PubMed

    Gombolay, Matthew; Golen, Toni; Shah, Neel; Shah, Julie

    2017-09-04

    Childbirth is a complex clinical service requiring the coordinated support of highly trained healthcare professionals as well as management of a finite set of critical resources (such as staff and beds) to provide safe care. The mode of delivery (vaginal delivery or cesarean section) has a significant effect on labor and delivery resource needs. Further, resource management decisions may impact the amount of time a physician or nurse is able to spend with any given patient. In this work, we employ queueing theory to model one year of transactional patient information at a tertiary care center in Boston, Massachusetts. First, we observe that the M/G/∞ model effectively predicts patient flow in an obstetrics department. This model captures the dynamics of labor and delivery where patients arrive randomly during the day, the duration of their stay is based on their individual acuity, and their labor progresses at some rate irrespective of whether they are given a bed. Second, using our queueing theoretic model, we show that reducing the rate of cesarean section - a current quality improvement goal in American obstetrics - may have important consequences with regard to the resource needs of a hospital. We also estimate the potential financial impact of these resource needs from the hospital perspective. Third, we report that application of our model to an analysis of potential patient coverage strategies supports the adoption of team-based care, in which attending physicians share responsibilities for patients.

  14. Network resiliency through memory health monitoring and proactive management

    DOEpatents

    Andrade Costa, Carlos H.; Cher, Chen-Yong; Park, Yoonho; Rosenburg, Bryan S.; Ryu, Kyung D.

    2017-11-21

    A method for managing a network queue memory includes receiving sensor information about the network queue memory, predicting a memory failure in the network queue memory based on the sensor information, and outputting a notification through a plurality of nodes forming a network and using the network queue memory, the notification configuring communications between the nodes.

  15. Medical ethics and new public management in Sweden.

    PubMed

    Hansson, Sven Ove

    2014-07-01

    In order to shorten queues to healthcare, the Swedish government has introduced a yearly "queue billion" that is paid out to the county councils in proportion to how successful they are in reducing queues. However, only the queues for first visits are covered. Evidence has accumulated that queues for return visits have become longer. This affects the chronically and severely ill. Swedish physicians, and the Swedish Medical Association, have strongly criticized the queue billion and have claimed that it conflicts with medical ethics. Instead they demand that their professional judgments on priority setting and medical urgency be respected. This discussion provides an interesting illustration of some of the limitations of new public management and also more generally of the complicated relationships between medical ethics and public policy.

  16. Priority Queues for Computer Simulations

    NASA Technical Reports Server (NTRS)

    Steinman, Jeffrey S. (Inventor)

    1998-01-01

    The present invention is embodied in new priority queue data structures for event list management of computer simulations, and includes a new priority queue data structure and an improved event horizon applied to priority queue data structures. ne new priority queue data structure is a Qheap and is made out of linked lists for robust, fast, reliable, and stable event list management and uses a temporary unsorted list to store all items until one of the items is needed. Then the list is sorted, next, the highest priority item is removed, and then the rest of the list is inserted in the Qheap. Also, an event horizon is applied to binary tree and splay tree priority queue data structures to form the improved event horizon for event management.

  17. Formulation of consumables management models. Development approach for the mission planning processor working model

    NASA Technical Reports Server (NTRS)

    Connelly, L. C.

    1977-01-01

    The mission planning processor is a user oriented tool for consumables management and is part of the total consumables subsystem management concept. The approach to be used in developing a working model of the mission planning processor is documented. The approach includes top-down design, structured programming techniques, and application of NASA approved software development standards. This development approach: (1) promotes cost effective software development, (2) enhances the quality and reliability of the working model, (3) encourages the sharing of the working model through a standard approach, and (4) promotes portability of the working model to other computer systems.

  18. General bulk service queueing system with N-policy, multiplevacations, setup time and server breakdown without interruption

    NASA Astrophysics Data System (ADS)

    Sasikala, S.; Indhira, K.; Chandrasekaran, V. M.

    2017-11-01

    In this paper, we have considered an MX / (a,b) / 1 queueing system with server breakdown without interruption, multiple vacations, setup times and N-policy. After a batch of service, if the size of the queue is ξ (< a), then the server immediately takes a vacation. Upon returns from a vacation, if the queue is less than N, then the server takes another vacation. This process continues until the server finds atleast N customers in the queue. After a vacation, if the server finds at least N customers waiting for service, then the server needs a setup time to start the service. After a batch of service, if the amount of waiting customers in the queue is ξ (≥ a) then the server serves a batch of min(ξ,b) customers, where b ≥ a. We derived the probability generating function of queue length at arbitrary time epoch. Further, we obtained some important performance measures.

  19. Multiprocessing on supercomputers for computational aerodynamics

    NASA Technical Reports Server (NTRS)

    Yarrow, Maurice; Mehta, Unmeel B.

    1991-01-01

    Little use is made of multiple processors available on current supercomputers (computers with a theoretical peak performance capability equal to 100 MFLOPS or more) to improve turnaround time in computational aerodynamics. The productivity of a computer user is directly related to this turnaround time. In a time-sharing environment, such improvement in this speed is achieved when multiple processors are used efficiently to execute an algorithm. The concept of multiple instructions and multiple data (MIMD) is applied through multitasking via a strategy that requires relatively minor modifications to an existing code for a single processor. This approach maps the available memory to multiple processors, exploiting the C-Fortran-Unix interface. The existing code is mapped without the need for developing a new algorithm. The procedure for building a code utilizing this approach is automated with the Unix stream editor.

  20. Time Is Not on Our Side: How Radiology Practices Should Manage Customer Queues.

    PubMed

    Loving, Vilert A; Ellis, Richard L; Rippee, Robert; Steele, Joseph R; Schomer, Donald F; Shoemaker, Stowe

    2017-11-01

    As health care shifts toward patient-centered care, wait times have received increasing scrutiny as an important metric for patient satisfaction. Long queues form when radiology practices inefficiently service their customers, leading to customer dissatisfaction and a lower perception of value. This article describes a four-step framework for radiology practices to resolve problematic queues: (1) analyze factors contributing to queue formation; (2) improve processes to reduce service times; (3) reduce variability; (4) address the psychology of queues. Copyright © 2017 American College of Radiology. Published by Elsevier Inc. All rights reserved.

  1. Prospects of a mathematical theory of human behavior in complex man-machine systems tasks. [time sharing computer analogy of automobile driving

    NASA Technical Reports Server (NTRS)

    Johannsen, G.; Rouse, W. B.

    1978-01-01

    A hierarchy of human activities is derived by analyzing automobile driving in general terms. A structural description leads to a block diagram and a time-sharing computer analogy. The range of applicability of existing mathematical models is considered with respect to the hierarchy of human activities in actual complex tasks. Other mathematical tools so far not often applied to man machine systems are also discussed. The mathematical descriptions at least briefly considered here include utility, estimation, control, queueing, and fuzzy set theory as well as artificial intelligence techniques. Some thoughts are given as to how these methods might be integrated and how further work might be pursued.

  2. Experiences of Fast Queue health care users in primary health care facilities in eThekwini district, South Africa.

    PubMed

    Sokhela, Dudu G; Makhanya, Nonhlanhla J; Sibiya, Nokuthula M; Nokes, Kathleen M

    2013-07-05

    Comprehensive Primary Health Care (PHC), based on the principles of accessibility, availability, affordability, equity and acceptability, was introduced in South Africa to address inequalities in health service provision. Whilst the Fast Queue was instrumental in the promotion of access to health care, a major goal of the PHC approach, facilities were not prepared for the sudden influx of clients. Increased access resulted in long waiting times and queues contributing to dissatisfaction with the service which could lead to missed appointments and non-compliance with established treatment plans. Firstly to describe the experiences of clients using the Fast Queue strategy to access routine healthcare services and secondly, to determine how the clients' experiences led to satisfaction or dissatisfaction with the Fast Queue service. A descriptive qualitative survey using content analysis explored the experiences of the Fast Queue users in a PHC setting. Setting was first identified based on greatest number using the Fast Queue and geographic diversity and then a convenience sample of health care users of the Fast Queue were sampled individually along with one focus group of users who accessed the Queue monthly for medication refills. The same interview guide questions were used for both individual interviews and the one focus group discussion. Five clinics with the highest number of attendees during a three month period and a total of 83 health care users of the Fast Queue were interviewed. The average participant was female, 31 years old, single and unemployed. Two themes with sub-themes emerged: health care user flow and communication, which highlights both satisfaction and dissatisfaction with the fast queue and queue marshals, could assist in directing users to the respective queues, reduce waiting time and keep users satisfied with the use of sign posts where there is a lack of human resources. Effective health communication strategies contribute to positive experiences by health care users and these can be effected by: (1) involvement of health care providers in planning the construction of health facilities to give input about patient flow, infection prevention and control and provision of privacy, (2) effective complaints mechanisms for users to ensure that complaints are followed up and (3)encouraging users to arrive at the facility throughout the day, rather than the present practice where all users arrive at the clinic early in the morning.

  3. A time-shared machine repair problem with mixed spares under N-policy

    NASA Astrophysics Data System (ADS)

    Jain, Madhu; Shekhar, Chandra; Shukla, Shalini

    2016-06-01

    The present investigation deals with a machine repair problem consisting of cold and warm standby machines. The machines are subject to breakdown and are repaired by the permanent repairman operating under N-policy. There is provision of one additional removable repairman who is called upon when the work load of failed machines crosses a certain threshold level and is removed as soon as the work load again ceases to that level. Both repairmen recover the failed machines by following the time sharing concept which means that the repairmen share their repair job simultaneously among all the failed machines that have joined the system for repair. Markovian model has been developed by considering the queue dependent rates and solved analytically using the recursive technique. Various performance indices are derived which are further used to obtain the cost function. By taking illustration, numerical simulation and sensitivity analysis have been provided.

  4. Performances of multiprocessor multidisk architectures for continuous media storage

    NASA Astrophysics Data System (ADS)

    Gennart, Benoit A.; Messerli, Vincent; Hersch, Roger D.

    1996-03-01

    Multimedia interfaces increase the need for large image databases, capable of storing and reading streams of data with strict synchronicity and isochronicity requirements. In order to fulfill these requirements, we consider a parallel image server architecture which relies on arrays of intelligent disk nodes, each disk node being composed of one processor and one or more disks. This contribution analyzes through bottleneck performance evaluation and simulation the behavior of two multi-processor multi-disk architectures: a point-to-point architecture and a shared-bus architecture similar to current multiprocessor workstation architectures. We compare the two architectures on the basis of two multimedia algorithms: the compute-bound frame resizing by resampling and the data-bound disk-to-client stream transfer. The results suggest that the shared bus is a potential bottleneck despite its very high hardware throughput (400Mbytes/s) and that an architecture with addressable local memories located closely to their respective processors could partially remove this bottleneck. The point- to-point architecture is scalable and able to sustain high throughputs for simultaneous compute- bound and data-bound operations.

  5. Performance and Application of Parallel OVERFLOW Codes on Distributed and Shared Memory Platforms

    NASA Technical Reports Server (NTRS)

    Djomehri, M. Jahed; Rizk, Yehia M.

    1999-01-01

    The presentation discusses recent studies on the performance of the two parallel versions of the aerodynamics CFD code, OVERFLOW_MPI and _MLP. Developed at NASA Ames, the serial version, OVERFLOW, is a multidimensional Navier-Stokes flow solver based on overset (Chimera) grid technology. The code has recently been parallelized in two ways. One is based on the explicit message-passing interface (MPI) across processors and uses the _MPI communication package. This approach is primarily suited for distributed memory systems and workstation clusters. The second, termed the multi-level parallel (MLP) method, is simple and uses shared memory for all communications. The _MLP code is suitable on distributed-shared memory systems. For both methods, the message passing takes place across the processors or processes at the advancement of each time step. This procedure is, in effect, the Chimera boundary conditions update, which is done in an explicit "Jacobi" style. In contrast, the update in the serial code is done in more of the "Gauss-Sidel" fashion. The programming efforts for the _MPI code is more complicated than for the _MLP code; the former requires modification of the outer and some inner shells of the serial code, whereas the latter focuses only on the outer shell of the code. The _MPI version offers a great deal of flexibility in distributing grid zones across a specified number of processors in order to achieve load balancing. The approach is capable of partitioning zones across multiple processors or sending each zone and/or cluster of several zones into a single processor. The message passing across the processors consists of Chimera boundary and/or an overlap of "halo" boundary points for each partitioned zone. The MLP version is a new coarse-grain parallel concept at the zonal and intra-zonal levels. A grouping strategy is used to distribute zones into several groups forming sub-processes which will run in parallel. The total volume of grid points in each group are approximately balanced. A proper number of threads are initially allocated to each group, and in subsequent iterations during the run-time, the number of threads are adjusted to achieve load balancing across the processes. Each process exploits the multitasking directives already established in Overflow.

  6. Apparatus and method for managing digital resources by passing digital resource tokens between queues

    DOEpatents

    Crawford, H.J.; Lindenstruth, V.

    1999-06-29

    A method of managing digital resources of a digital system includes the step of reserving token values for certain digital resources in the digital system. A selected token value in a free-buffer-queue is then matched to an incoming digital resource request. The selected token value is then moved to a valid-request-queue. The selected token is subsequently removed from the valid-request-queue to allow a digital agent in the digital system to process the incoming digital resource request associated with the selected token. Thereafter, the selected token is returned to the free-buffer-queue. 6 figs.

  7. Two tandem queues with general renewal input. 2: Asymptotic expansions for the diffusion model

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Knessl, C.; Tier, C.

    1999-10-01

    In Part 1 the authors formulated and solved a diffusion model for two tandem queues with exponential servers and general renewal arrivals. They thus obtained the easy traffic diffusion approximation to the steady state joint queue length distribution for this network. Here they study asymptotic and numerical properties of the diffusion approximation. In particular, analytical expressions are obtained for the tail probabilities. Both the joint distribution of the two queues and the marginal distribution of the second queue are considered. They also give numerical illustrations of how this marginal is affected by changes in the arrival and service processes.

  8. Apparatus and method for managing digital resources by passing digital resource tokens between queues

    DOEpatents

    Crawford, Henry J.; Lindenstruth, Volker

    1999-01-01

    A method of managing digital resources of a digital system includes the step of reserving token values for certain digital resources in the digital system. A selected token value in a free-buffer-queue is then matched to an incoming digital resource request. The selected token value is then moved to a valid-request-queue. The selected token is subsequently removed from the valid-request-queue to allow a digital agent in the digital system to process the incoming digital resource request associated with the selected token. Thereafter, the selected token is returned to the free-buffer-queue.

  9. WATERLOPP V2/64: A highly parallel machine for numerical computation

    NASA Astrophysics Data System (ADS)

    Ostlund, Neil S.

    1985-07-01

    Current technological trends suggest that the high performance scientific machines of the future are very likely to consist of a large number (greater than 1024) of processors connected and communicating with each other in some as yet undetermined manner. Such an assembly of processors should behave as a single machine in obtaining numerical solutions to scientific problems. However, the appropriate way of organizing both the hardware and software of such an assembly of processors is an unsolved and active area of research. It is particularly important to minimize the organizational overhead of interprocessor comunication, global synchronization, and contention for shared resources if the performance of a large number ( n) of processors is to be anything like the desirable n times the performance of a single processor. In many situations, adding a processor actually decreases the performance of the overall system since the extra organizational overhead is larger than the extra processing power added. The systolic loop architecture is a new multiple processor architecture which attemps at a solution to the problem of how to organize a large number of asynchronous processors into an effective computational system while minimizing the organizational overhead. This paper gives a brief overview of the basic systolic loop architecture, systolic loop algorithms for numerical computation, and a 64-processor implementation of the architecture, WATERLOOP V2/64, that is being used as a testbed for exploring the hardware, software, and algorithmic aspects of the architecture.

  10. Parallel algorithms for boundary value problems

    NASA Technical Reports Server (NTRS)

    Lin, Avi

    1990-01-01

    A general approach to solve boundary value problems numerically in a parallel environment is discussed. The basic algorithm consists of two steps: the local step where all the P available processors work in parallel, and the global step where one processor solves a tridiagonal linear system of the order P. The main advantages of this approach are two fold. First, this suggested approach is very flexible, especially in the local step and thus the algorithm can be used with any number of processors and with any of the SIMD or MIMD machines. Secondly, the communication complexity is very small and thus can be used as easily with shared memory machines. Several examples for using this strategy are discussed.

  11. C-MOS array design techniques: SUMC multiprocessor system study

    NASA Technical Reports Server (NTRS)

    Clapp, W. A.; Helbig, W. A.; Merriam, A. S.

    1972-01-01

    The current capabilities of LSI techniques for speed and reliability, plus the possibilities of assembling large configurations of LSI logic and storage elements, have demanded the study of multiprocessors and multiprocessing techniques, problems, and potentialities. Evaluated are three previous systems studies for a space ultrareliable modular computer multiprocessing system, and a new multiprocessing system is proposed that is flexibly configured with up to four central processors, four 1/0 processors, and 16 main memory units, plus auxiliary memory and peripheral devices. This multiprocessor system features a multilevel interrupt, qualified S/360 compatibility for ground-based generation of programs, virtual memory management of a storage hierarchy through 1/0 processors, and multiport access to multiple and shared memory units.

  12. A novel fair active queue management algorithm based on traffic delay jitter

    NASA Astrophysics Data System (ADS)

    Wang, Xue-Shun; Yu, Shao-Hua; Dai, Jin-You; Luo, Ting

    2009-11-01

    In order to guarantee the quantity of data traffic delivered in the network, congestion control strategy is adopted. According to the study of many active queue management (AQM) algorithms, this paper proposes a novel active queue management algorithm named JFED. JFED can stabilize queue length at a desirable level by adjusting output traffic rate and adopting a reasonable calculation of packet drop probability based on buffer queue length and traffic jitter; and it support burst packet traffic through the packet delay jitter, so that it can traffic flow medium data. JFED impose effective punishment upon non-responsible flow with a full stateless method. To verify the performance of JFED, it is implemented in NS2 and is compared with RED and CHOKe with respect to different performance metrics. Simulation results show that the proposed JFED algorithm outperforms RED and CHOKe in stabilizing instantaneous queue length and in fairness. It is also shown that JFED enables the link capacity to be fully utilized by stabilizing the queue length at a desirable level, while not incurring excessive packet loss ratio.

  13. Evaluation of roadway sites for queue management.

    DOT National Transportation Integrated Search

    1991-01-01

    This study addresses the problem of queueing on highway facilities, wherein a large number of computerized methods for the analysis of different queueing situations are available. A three-tier classification system of the methodologies was used with ...

  14. Throughput-optimal scheduling for broadcast channels

    NASA Astrophysics Data System (ADS)

    Eryilmaz, Atilla; Srikant, Rayadurgam; Perkins, James R.

    2001-07-01

    In this paper, we consider a degraded Gaussian broadcast channel, where the transmitter maintains separate queues for each receiver. We present throughput optimal policies that stabilize the queues without knowing the statistics of the arrival processes to these queues.

  15. Queues with Dropping Functions and General Arrival Processes

    PubMed Central

    Chydzinski, Andrzej; Mrozowski, Pawel

    2016-01-01

    In a queueing system with the dropping function the arriving customer can be denied service (dropped) with the probability that is a function of the queue length at the time of arrival of this customer. The potential applicability of such mechanism is very wide due to the fact that by choosing the shape of this function one can easily manipulate several performance characteristics of the queueing system. In this paper we carry out analysis of the queueing system with the dropping function and a very general model of arrival process—the model which includes batch arrivals and the interarrival time autocorrelation, and allows for fitting the actual shape of the interarrival time distribution and its moments. For such a system we obtain formulas for the distribution of the queue length and the overall customer loss ratio. The analytical results are accompanied with numerical examples computed for several dropping functions. PMID:26943171

  16. Nonfixed Retirement Age for University Professors: Modeling Its Effects on New Faculty Hires.

    PubMed

    Larson, Richard C; Diaz, Mauricio Gomez

    2012-03-01

    We model the set of tenure-track faculty members at a university as a queue, where "customers" in queue are faculty members in active careers. Arrivals to the queue are usually young, untenured assistant professors, and departures from the queue are primarily those who do not pass a promotion or tenure hurdle and those who retire. There are other less-often-used ways to enter and leave the queue. Our focus is on system effects of the elimination of mandatory retirement age. In particular, we are concerned with estimating the number of assistant professor slots that annually are no longer available because of the elimination of mandatory retirement. We start with steady-state assumptions that require use of Little's Law of Queueing, and we progress to a transient model using system dynamics. We apply these simple models using available data from our home university, the Massachusetts Institute of Technology.

  17. Nonfixed Retirement Age for University Professors: Modeling Its Effects on New Faculty Hires

    PubMed Central

    Larson, Richard C.; Diaz, Mauricio Gomez

    2013-01-01

    We model the set of tenure-track faculty members at a university as a queue, where “customers” in queue are faculty members in active careers. Arrivals to the queue are usually young, untenured assistant professors, and departures from the queue are primarily those who do not pass a promotion or tenure hurdle and those who retire. There are other less-often-used ways to enter and leave the queue. Our focus is on system effects of the elimination of mandatory retirement age. In particular, we are concerned with estimating the number of assistant professor slots that annually are no longer available because of the elimination of mandatory retirement. We start with steady-state assumptions that require use of Little’s Law of Queueing, and we progress to a transient model using system dynamics. We apply these simple models using available data from our home university, the Massachusetts Institute of Technology. PMID:23936582

  18. Methods for synchronizing a countdown routine of a timer key and electronic device

    DOEpatents

    Condit, Reston A.; Daniels, Michael A.; Clemens, Gregory P.; Tomberlin, Eric S.; Johnson, Joel A.

    2015-06-02

    A timer key relating to monitoring a countdown time of a countdown routine of an electronic device is disclosed. The timer key comprises a processor configured to respond to a countdown time associated with operation of the electronic device, a display operably coupled with the processor, and a housing configured to house at least the processor. The housing has an associated structure configured to engage with the electronic device to share the countdown time between the electronic device and the timer key. The processor is configured to begin a countdown routine based at least in part on the countdown time, wherein the countdown routine is at least substantially synchronized with a countdown routine of the electronic device when the timer key is removed from the electronic device. A system and method for synchronizing countdown routines of a timer key and an electronic device are also disclosed.

  19. Apparatus, system, and method for synchronizing a timer key

    DOEpatents

    Condit, Reston A; Daniels, Michael A; Clemens, Gregory P; Tomberlin, Eric S; Johnson, Joel A

    2014-04-22

    A timer key relating to monitoring a countdown time of a countdown routine of an electronic device is disclosed. The timer key comprises a processor configured to respond to a countdown time associated with operation of the electronic device, a display operably coupled with the processor, and a housing configured to house at least the processor. The housing has an associated structure configured to engage with the electronic device to share the countdown time between the electronic device and the timer key. The processor is configured to begin a countdown routine based at least in part on the countdown time, wherein the countdown routine is at least substantially synchronized with a countdown routine of the electronic device when the timer key is removed from the electronic device. A system and method for synchronizing countdown routines of a timer key and an electronic device are also disclosed.

  20. Data preprocessing for determining outer/inner parallelization in the nested loop problem using OpenMP

    NASA Astrophysics Data System (ADS)

    Handhika, T.; Bustamam, A.; Ernastuti, Kerami, D.

    2017-07-01

    Multi-thread programming using OpenMP on the shared-memory architecture with hyperthreading technology allows the resource to be accessed by multiple processors simultaneously. Each processor can execute more than one thread for a certain period of time. However, its speedup depends on the ability of the processor to execute threads in limited quantities, especially the sequential algorithm which contains a nested loop. The number of the outer loop iterations is greater than the maximum number of threads that can be executed by a processor. The thread distribution technique that had been found previously only be applied by the high-level programmer. This paper generates a parallelization procedure for low-level programmer in dealing with 2-level nested loop problems with the maximum number of threads that can be executed by a processor is smaller than the number of the outer loop iterations. Data preprocessing which is related to the number of the outer loop and the inner loop iterations, the computational time required to execute each iteration and the maximum number of threads that can be executed by a processor are used as a strategy to determine which parallel region that will produce optimal speedup.

  1. Evaluation of DOTD's Existing Queue Estimation Procedures : Research Project Capsule

    DOT National Transportation Integrated Search

    2017-10-01

    The primary objective of this study is to evaluate the effectiveness of DOTDs queue estimation procedures by comparing results with those obtained directly from site observations through video camera footage or other means. Actual queue start time...

  2. Computing moving and intermittent queue propagation in highway work zones.

    DOT National Transportation Integrated Search

    2012-07-01

    Drivers may experience intermittent congestion and moving queue conditions in work zones due to several reasons such as presence of lane closure, roadway geometric changes, higher demand, lower speed, and reduced capacity. The congestion and queue ha...

  3. An Adaptive Property-Aware HW/SW Framework for DDDAS

    DTIC Science & Technology

    2014-10-21

    sleep queue stores sleeping tasks until their activation time. The task with the earliest activation time is at the front of the sleep queue. At the...queue) or activation time ( sleep queue). Chetan et al. / Procedia Computer Science 00 (2012) 1–9 4 Figure 2: A high level architecture diagram of the...conservative will be the WCET estimation. Vestal et al. suggested the use of Audesly’s prioirity assignment scheme [6] and period transformation technique

  4. A dynamic routing strategy with limited buffer on scale-free network

    NASA Astrophysics Data System (ADS)

    Wang, Yufei; Liu, Feng

    2016-04-01

    In this paper, we propose an integrated routing strategy based on global static topology information and local dynamic data packet queue lengths to improve the transmission efficiency of scale-free networks. The proposed routing strategy is a combination of a global static routing strategy (based on the shortest path algorithm) and local dynamic queue length management, in which, instead of using an infinite buffer, the queue length of each node i in the proposed routing strategy is limited by a critical queue length Qic. When the network traffic is lower and the queue length of each node i is shorter than its critical queue length Qic, it forwards packets according to the global routing table. With increasing network traffic, when the buffers of the nodes with higher degree are full, they do not receive packets due to their limited buffers and the packets have to be delivered to the nodes with lower degree. The global static routing strategy can shorten the transmission time that it takes a packet to reach its destination, and the local limited queue length can balance the network traffic. The optimal critical queue lengths of nodes have been analysed. Simulation results show that the proposed routing strategy can get better performance than that of the global static strategy based on topology, and almost the same performance as that of the global dynamic routing strategy with less complexity.

  5. OpenMP Performance on the Columbia Supercomputer

    NASA Technical Reports Server (NTRS)

    Haoqiang, Jin; Hood, Robert

    2005-01-01

    This presentation discusses Columbia World Class Supercomputer which is one of the world's fastest supercomputers providing 61 TFLOPs (10/20/04). Conceived, designed, built, and deployed in just 120 days. A 20-node supercomputer built on proven 512-processor nodes. The largest SGI system in the world with over 10,000 Intel Itanium 2 processors and provides the largest node size incorporating commodity parts (512) and the largest shared-memory environment (2048) with 88% efficiency tops the scalar systems on the Top500 list.

  6. Hypercluster Parallel Processor

    NASA Technical Reports Server (NTRS)

    Blech, Richard A.; Cole, Gary L.; Milner, Edward J.; Quealy, Angela

    1992-01-01

    Hypercluster computer system includes multiple digital processors, operation of which coordinated through specialized software. Configurable according to various parallel-computing architectures of shared-memory or distributed-memory class, including scalar computer, vector computer, reduced-instruction-set computer, and complex-instruction-set computer. Designed as flexible, relatively inexpensive system that provides single programming and operating environment within which one can investigate effects of various parallel-computing architectures and combinations on performance in solution of complicated problems like those of three-dimensional flows in turbomachines. Hypercluster software and architectural concepts are in public domain.

  7. Hybrid WDM/TDM PON Using the AWG FSR and Featuring Centralized Light Generation and Dynamic Bandwidth Allocation

    NASA Astrophysics Data System (ADS)

    Bock, Carlos; Prat, Josep; Walker, Stuart D.

    2005-12-01

    A novel time/space/wavelength division multiplexing (TDM/WDM) architecture using the free spectral range (FSR) periodicity of the arrayed waveguide grating (AWG) is presented. A shared tunable laser and a photoreceiver stack featuring dynamic bandwidth allocation (DBA) and remote modulation are used for transmission and reception. Transmission tests show correct operation at 2.5 Gb/s to a 30-km reach, and network performance calculations using queue modeling demonstrate that a high-bandwidth-demanding application could be deployed on this network.

  8. The evaluation of a formalized queue management system for coronary angiography waiting lists.

    PubMed

    Alter, D A; Newman, Alice M; Cohen, Eric A; Sykora, Kathy; Tu, Jack V

    2005-11-01

    Lengthy waiting lists for coronary angiography have been described in many health care systems worldwide. The extent to which formal queue management systems may improve the prioritization and survival of patients in the angiography queue is unknown. To prospectively evaluate the performance of a formal queue management system for patients awaiting coronary angiography in Ontario. The coronary angiography urgency scale, a formal queue management system developed in 1993 using a modified Delphi panel, allocates recommended maximum waiting times (RMWTs) in accordance with clinical necessity. By using a provincial clinical registry, 35,617 consecutive patients referred into the coronary angiography queue between April 1, 2001, and March 31, 2002, were prospectively tracked. Cox proportional hazards models were used to examined mortality risk across urgency after adjusting for additional clinical and comorbid factors. Good agreement was determined in urgency ratings between scores from the coronary angiography urgency scale and implicit physician judgement, which was obtained independently at the time of the index referral (weighted kappa = 0.49). The overall mortality in the queue was 0.3% (0.47%, 0.26% and 0.13% for urgent, semiurgent and elective patients, respectively). Urgency, as specified by the coronary angiography urgency scale, was the strongest predictor of death in the queue (P<0.001). However, when patients were censored according to their RMWTs, mortality was similar across different levels of urgency. Consequently, up to 18.5 deaths per 10,000 patients could have potentially been averted had patients been triaged and undergone coronary angiography within the RMWT as specified by the coronary angiography urgency scale. The incorporation of the coronary angiography urgency scale as a formal queue management system may decrease mortality in the coronary angiography queue. The authors recommend its implementation in health care systems where patients experience excessive waiting time delays for coronary angiography.

  9. Reducing a congestion with introduce the greedy algorithm on traffic light control

    NASA Astrophysics Data System (ADS)

    Catur Siswipraptini, Puji; Hendro Martono, Wisnu; Hartanti, Dian

    2018-03-01

    The density of vehicles causes congestion seen at every junction in the city of jakarta due to the static or manual traffic timing lamp system consequently the length of the queue at the junction is uncertain. The research has been aimed at designing a sensor based traffic system based on the queue length detection of the vehicle to optimize the duration of the green light. In detecting the length of the queue of vehicles using infrared sensor assistance placed in each intersection path, then apply Greedy algorithm to help accelerate the movement of green light duration for the path that requires, while to apply the traffic lights regulation program based on greedy algorithm which is then stored on microcontroller with Arduino Mega 2560 type. Where a developed system implements the greedy algorithm with the help of the infrared sensor it will extend the duration of the green light on the long vehicle queue and accelerate the duration of the green light at the intersection that has the queue not too dense. Furthermore, the design is made to form an artificial form of the actual situation of the scale model or simple simulator (next we just called as scale model of simulator) of the intersection then tested. Sensors used are infrared sensors, where the placement of sensors in each intersection on the scale model is placed within 10 cm of each sensor and serves as a queue detector. From the results of the test process on the scale model with a longer queue obtained longer green light time so it will fix the problem of long queue of vehicles. Using greedy algorithms can add long green lights for 2 seconds on tracks that have long queues at least three sensor levels and accelerate time at other intersections that have longer queue sensor levels less than level three.

  10. B-1B Avionics/Automatic Test Equipment: Maintenance Queueing Analysis.

    DTIC Science & Technology

    1983-12-01

    analysis (which is logistics terminology for an avionics/ATE queueing analysis). To allow each vendor the opportunity to perform such an analysis...for system performance measures may be found for the queueing system in Figure 7. This is due to the preemptive blocking caused by ATE failures. The...D-R14l1i75 B-iB AVIONICS/AUTOMPTIC TEST EQUIPMENT: MRINTENRNCE 1/2 QUEUEING RNRLYSIS(U) RIP FORCE INST OF TECH HRIGHT-PRTTERSON RFB OH SCHOOL OF

  11. On-Line Scheduling of Parallel Machines

    DTIC Science & Technology

    1990-11-01

    machine without losing any work; this is referred to as the preemptive model. In contrast to the nonpreemptive model which we have considered in this paper...that there exists no schedule of length d. The 2-relaxed decision procedure is as follows. Put each job into the queue of the slowest machine Mk such...in their queues . If a machine’s queue is empty it takes jobs to process from the queue of the first machine that is slower than it and that has a

  12. The Sojourn Time in a Three Node, Acyclic, Jackson Queueing Network.

    DTIC Science & Technology

    1982-01-27

    Effect of Intermediate Storage on Production Lines with Dependent Machines, Robert D. Foley and Petcharat Chansaenwilai 8015 Some Conditions for the...Queues, Robert D. Foley 8105 Reversibility of Production Lines with Dependent Machines, Petcharat Chansaenwilai 1 8106 Queues with Delayed Feedback, Robert

  13. Method and apparatus for efficiently tracking queue entries relative to a timestamp

    DOEpatents

    Blumrich, Matthias A.; Chen, Dong; Gara, Alan G.; Giampapa, Mark E.; Heidelberger, Philip; Ohmacht, Martin; Salapura, Velentina; Vranas, Pavlos

    2014-06-17

    An apparatus and method for tracking coherence event signals transmitted in a multiprocessor system. The apparatus comprises a coherence logic unit, each unit having a plurality of queue structures with each queue structure associated with a respective sender of event signals transmitted in the system. A timing circuit associated with a queue structure controls enqueuing and dequeuing of received coherence event signals, and, a counter tracks a number of coherence event signals remaining enqueued in the queue structure and dequeued since receipt of a timestamp signal. A counter mechanism generates an output signal indicating that all of the coherence event signals present in the queue structure at the time of receipt of the timestamp signal have been dequeued. In one embodiment, the timestamp signal is asserted at the start of a memory synchronization operation and, the output signal indicates that all coherence events present when the timestamp signal was asserted have completed. This signal can then be used as part of the completion condition for the memory synchronization operation.

  14. How to report and monitor the performance of waiting list management.

    PubMed

    Torkki, Markus; Linna, Miika; Seitsalo, Seppo; Paavolainen, Pekka

    2002-01-01

    Potential problems concerning waiting list management are often monitored using mean waiting times based on empirical samples. However, the appropriateness of mean waiting time as an indicator of access can be questioned if a waiting list is not managed well, e.g., if the queue discipline is violated. This study was performed to find out about the queue discipline in waiting lists for elective surgery to reveal potential discrepancies in waiting list management. There were 1,774 waiting list patients for hallux valgus or varicose vein surgery or sterilization. The waiting time distributions of patients receiving surgery and of patients still waiting for an operation are presented in column charts. The charts are compared with two model charts. One model chart presents a high queue discipline (first in-first out) and another a poor queue discipline (random) queue. There were significant differences in waiting list management across hospitals and patient categories. Examples of a poor queue discipline were found in queues for hallux valgus and varicose vein operations. A routine waiting list reporting should be used to guarantee the quality of waiting list management and to pinpoint potential problems in access. It is important to monitor not only the number of patients in the waiting list but also the queue discipline and the balance between demand and supply of surgical services. The purpose for this type of reporting is to ensure that the priority setting made at health policy level also works in practise.

  15. Interference Drop Scheme: Enhancing QoS Provision in Multi-Hop Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Luo, Chang-Yi; Komuro, Nobuyoshi; Takahashi, Kiyoshi; Kasai, Hiroyuki; Ueda, Hiromi; Tsuboi, Toshinori

    Ad hoc networking uses wireless technologies to construct networks with no physical infrastructure and so are expected to provide instant networking in areas such as disaster recovery sites and inter-vehicle communication. Unlike conventional wired networks services, services in ad hoc networks are easily disrupted by the frequent changes in traffic and topology. Therefore, solutions to assure the Quality of Services (QoS) in ad hoc networks are different from the conventional ones used in wired networks. In this paper, we propose a new queue management scheme, Interference Drop Scheme (IDS) for ad hoc networks. In the conventional queue management approaches such as FIFO (First-in First-out) and RED (Random Early Detection), a queue is usually managed by a queue length limit. FIFO discards packets according to the queue limit, and RED discards packets in an early and random fashion. IDS, on the other hand, manages the queue according to wireless interference time, which increases as the number of contentions in the MAC layer increases. When there are many MAC contentions, IDS discards TCP data packets. By observing the interference time and discarding TCP data packets, our simulation results show that IDS improves TCP performance and reduces QoS violations in UDP in ad hoc networks with chain, grid, and random topologies. Our simulation results also demonstrate that wireless interference time is a better metric than queue length limit for queue management in multi-hop ad hoc networks.

  16. Queues and Reference Service: Some Implications for Staffing

    ERIC Educational Resources Information Center

    Regazzi, John J.; Hersberger, Rodney M.

    1978-01-01

    This study at an academic library used a simulation technique (1) to analyze the extent to which queues develop at a reference desk during peak periods, (2) to propose alternative staffing models to reduce queues, and (3) to examine the cost effectiveness of the alternatives. (Author/JAB)

  17. Call Admission Control on Single Node Networks under Output Rate-Controlled Generalized Processor Sharing (ORC-GPS) Scheduler

    NASA Astrophysics Data System (ADS)

    Hanada, Masaki; Nakazato, Hidenori; Watanabe, Hitoshi

    Multimedia applications such as music or video streaming, video teleconferencing and IP telephony are flourishing in packet-switched networks. Applications that generate such real-time data can have very diverse quality-of-service (QoS) requirements. In order to guarantee diverse QoS requirements, the combined use of a packet scheduling algorithm based on Generalized Processor Sharing (GPS) and leaky bucket traffic regulator is the most successful QoS mechanism. GPS can provide a minimum guaranteed service rate for each session and tight delay bounds for leaky bucket constrained sessions. However, the delay bounds for leaky bucket constrained sessions under GPS are unnecessarily large because each session is served according to its associated constant weight until the session buffer is empty. In order to solve this problem, a scheduling policy called Output Rate-Controlled Generalized Processor Sharing (ORC-GPS) was proposed in [17]. ORC-GPS is a rate-based scheduling like GPS, and controls the service rate in order to lower the delay bounds for leaky bucket constrained sessions. In this paper, we propose a call admission control (CAC) algorithm for ORC-GPS, for leaky-bucket constrained sessions with deterministic delay requirements. This CAC algorithm for ORC-GPS determines the optimal values of parameters of ORC-GPS from the deterministic delay requirements of the sessions. In numerical experiments, we compare the CAC algorithm for ORC-GPS with one for GPS in terms of schedulable region and computational complexity.

  18. 41 CFR 105-60.402-2 - Response to initial requests.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Management Regulations System (Continued) GENERAL SERVICES ADMINISTRATION Regional Offices-General Services... denial. (e) GSA may, at its discretion, establish three processing queues based on whether any requests... each queue, responses will be prepared on a “first in, first out” basis. One queue will be made up of...

  19. Performance characteristics of a batch service queueing system with functioning server failure and multiple vacations

    NASA Astrophysics Data System (ADS)

    Niranjan, S. P.; Chandrasekaran, V. M.; Indhira, K.

    2018-04-01

    This paper examines bulk arrival and batch service queueing system with functioning server failure and multiple vacations. Customers are arriving into the system in bulk according to Poisson process with rate λ. Arriving customers are served in batches with minimum of ‘a’ and maximum of ‘b’ number of customers according to general bulk service rule. In the service completion epoch if the queue length is less than ‘a’ then the server leaves for vacation (secondary job) of random length. After a vacation completion, if the queue length is still less than ‘a’ then the server leaves for another vacation. The server keeps on going vacation until the queue length reaches the value ‘a’. The server is not stable at all the times. Sometimes it may fails during functioning of customers. Though the server fails service process will not be interrupted.It will be continued for the current batch of customers with lower service rate than the regular service rate. The server will be repaired after the service completion with lower service rate. The probability generating function of the queue size at an arbitrary time epoch will be obtained for the modelled queueing system by using supplementary variable technique. Moreover various performance characteristics will also be derived with suitable numerical illustrations.

  20. Multi-core processing and scheduling performance in CMS

    NASA Astrophysics Data System (ADS)

    Hernández, J. M.; Evans, D.; Foulkes, S.

    2012-12-01

    Commodity hardware is going many-core. We might soon not be able to satisfy the job memory needs per core in the current single-core processing model in High Energy Physics. In addition, an ever increasing number of independent and incoherent jobs running on the same physical hardware not sharing resources might significantly affect processing performance. It will be essential to effectively utilize the multi-core architecture. CMS has incorporated support for multi-core processing in the event processing framework and the workload management system. Multi-core processing jobs share common data in memory, such us the code libraries, detector geometry and conditions data, resulting in a much lower memory usage than standard single-core independent jobs. Exploiting this new processing model requires a new model in computing resource allocation, departing from the standard single-core allocation for a job. The experiment job management system needs to have control over a larger quantum of resource since multi-core aware jobs require the scheduling of multiples cores simultaneously. CMS is exploring the approach of using whole nodes as unit in the workload management system where all cores of a node are allocated to a multi-core job. Whole-node scheduling allows for optimization of the data/workflow management (e.g. I/O caching, local merging) but efficient utilization of all scheduled cores is challenging. Dedicated whole-node queues have been setup at all Tier-1 centers for exploring multi-core processing workflows in CMS. We present the evaluation of the performance scheduling and executing multi-core workflows in whole-node queues compared to the standard single-core processing workflows.

  1. CaLRS: A Critical-Aware Shared LLC Request Scheduling Algorithm on GPGPU

    PubMed Central

    Ma, Jianliang; Meng, Jinglei; Chen, Tianzhou; Wu, Minghui

    2015-01-01

    Ultra high thread-level parallelism in modern GPUs usually introduces numerous memory requests simultaneously. So there are always plenty of memory requests waiting at each bank of the shared LLC (L2 in this paper) and global memory. For global memory, various schedulers have already been developed to adjust the request sequence. But we find few work has ever focused on the service sequence on the shared LLC. We measured that a big number of GPU applications always queue at LLC bank for services, which provide opportunity to optimize the service order on LLC. Through adjusting the GPU memory request service order, we can improve the schedulability of SM. So we proposed a critical-aware shared LLC request scheduling algorithm (CaLRS) in this paper. The priority representative of memory request is critical for CaLRS. We use the number of memory requests that originate from the same warp but have not been serviced when they arrive at the shared LLC bank to represent the criticality of each warp. Experiments show that the proposed scheme can boost the SM schedulability effectively by promoting the scheduling priority of the memory requests with high criticality and improves the performance of GPU indirectly. PMID:25729772

  2. Transient probabilities for queues with applications to hospital waiting list management.

    PubMed

    Joy, Mark; Jones, Simon

    2005-08-01

    In this paper we study queuing systems within the NHS. Recently imposed government performance targets lead NHS executives to investigate and instigate alternative management strategies, thereby imposing structural changes on the queues. Under such circumstances, it is most unlikely that such systems are in equilibrium. It is crucial, in our opinion, to recognise this state of affairs in order to make a balanced assessment of the role of queue management in the modern NHS. From a mathematical perspective it should be emphasised that measures of the state of a queue based upon the assumption of statistical equilibrium (a pervasive methodology in the study of queues) are simply wrong in the above scenario. To base strategic decisions around such ideas is therefore highly questionable and it is one of the purposes of this paper to offer alternatives: we present some (recent) research whose results generate performance measures and measures of risk, for example, of waiting-times growing unacceptably large; we emphasise that these results concern the transient behaviour of the queueing model-there is no asssumption of statistical equilibrium. We also demonstrate that our results are computationally tractable.

  3. Single stage queueing/manufacturing system model that involves emission variable

    NASA Astrophysics Data System (ADS)

    Murdapa, P. S.; Pujawan, I. N.; Karningsih, P. D.; Nasution, A. H.

    2018-04-01

    Queueing is commonly occured at every industry. The basic model of queueing theory gives a foundation for modeling a manufacturing system. Nowadays, carbon emission is an important and inevitable issue due to its huge impact to our environment. However, existing model of queuing applied for analysis of single stage manufacturing system has not taken Carbon emissions into consideration. If it is applied to manufacturing context, it may lead to improper decisisions. By taking into account of emission variables into queuing models, not only the model become more comprehensive but also it creates awareness on the issue to many parties that involves in the system. This paper discusses the single stage M/M/1 queueing model that involves emission variable. Hopefully it could be a starting point for the next more complex models. It has a main objective for determining how carbon emissions could fit into the basic queueing theory. It turned out that the involvement of emission variables into the model has modified the traditional model of a single stage queue to a calculation model of production lot quantity allowed per period.

  4. High speed quantitative digital microscopy

    NASA Technical Reports Server (NTRS)

    Castleman, K. R.; Price, K. H.; Eskenazi, R.; Ovadya, M. M.; Navon, M. A.

    1984-01-01

    Modern digital image processing hardware makes possible quantitative analysis of microscope images at high speed. This paper describes an application to automatic screening for cervical cancer. The system uses twelve MC6809 microprocessors arranged in a pipeline multiprocessor configuration. Each processor executes one part of the algorithm on each cell image as it passes through the pipeline. Each processor communicates with its upstream and downstream neighbors via shared two-port memory. Thus no time is devoted to input-output operations as such. This configuration is expected to be at least ten times faster than previous systems.

  5. Using SDI-12 with ST microelectronics MCU's

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Saari, Alexandra; Hinzey, Shawn Adrian; Frigo, Janette Rose

    2015-09-03

    ST Microelectronics microcontrollers and processors are readily available, capable and economical processors. Unfortunately they lack a broad user base like similar offerings from Texas Instrument, Atmel, or Microchip. All of these devices could be useful in economical devices for remote sensing applications used with environmental sensing. With the increased need for environmental studies, and limited budgets, flexibility in hardware is very important. To that end, and in an effort to increase open support of ST devices, I am sharing my teams' experience in interfacing a common environmental sensor communication protocol (SDI-12) with ST devices.

  6. Multitasking OS manages a team of processors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ripps, D.L.

    1983-07-21

    MTOS-68k is a real-time multitasking operating system designed for the popular MC68000 microprocessors. It aproaches task coordination and synchronization in a fashion that matches uniquely the structural simplicity and regularity of the 68000 instruction set. Since in many 68000 applications the speed and power of one CPU are not enough, MTOS-68k has been designed to support multiple processors, as well as multiple tasks. Typically, the devices are tightly coupled single-board computers, that is they share a backplane and parts of global memory.

  7. Second International Workshop on Software Engineering and Code Design in Parallel Meteorological and Oceanographic Applications

    NASA Technical Reports Server (NTRS)

    OKeefe, Matthew (Editor); Kerr, Christopher L. (Editor)

    1998-01-01

    This report contains the abstracts and technical papers from the Second International Workshop on Software Engineering and Code Design in Parallel Meteorological and Oceanographic Applications, held June 15-18, 1998, in Scottsdale, Arizona. The purpose of the workshop is to bring together software developers in meteorology and oceanography to discuss software engineering and code design issues for parallel architectures, including Massively Parallel Processors (MPP's), Parallel Vector Processors (PVP's), Symmetric Multi-Processors (SMP's), Distributed Shared Memory (DSM) multi-processors, and clusters. Issues to be discussed include: (1) code architectures for current parallel models, including basic data structures, storage allocation, variable naming conventions, coding rules and styles, i/o and pre/post-processing of data; (2) designing modular code; (3) load balancing and domain decomposition; (4) techniques that exploit parallelism efficiently yet hide the machine-related details from the programmer; (5) tools for making the programmer more productive; and (6) the proliferation of programming models (F--, OpenMP, MPI, and HPF).

  8. Resource and Performance Evaluations of Fixed Point QRD-RLS Systolic Array through FPGA Implementation

    NASA Astrophysics Data System (ADS)

    Yokoyama, Yoshiaki; Kim, Minseok; Arai, Hiroyuki

    At present, when using space-time processing techniques with multiple antennas for mobile radio communication, real-time weight adaptation is necessary. Due to the progress of integrated circuit technology, dedicated processor implementation with ASIC or FPGA can be employed to implement various wireless applications. This paper presents a resource and performance evaluation of the QRD-RLS systolic array processor based on fixed-point CORDIC algorithm with FPGA. In this paper, to save hardware resources, we propose the shared architecture of a complex CORDIC processor. The required precision of internal calculation, the circuit area for the number of antenna elements and wordlength, and the processing speed will be evaluated. The resource estimation provides a possible processor configuration with a current FPGA on the market. Computer simulations assuming a fading channel will show a fast convergence property with a finite number of training symbols. The proposed architecture has also been implemented and its operation was verified by beamforming evaluation through a radio propagation experiment.

  9. Numbers or apologies? Customer reactions to telephone waiting time fillers.

    PubMed

    Munichor, Nira; Rafaeli, Anat

    2007-03-01

    The authors examined the effect of time perception and sense of progress in telephone queues on caller reactions to 3 telephone waiting time fillers: music, apologies, and information about location in the queue. In Study 1, conducted on 123 real calls, call abandonment was lowest, and call evaluations were most positive with information about location in the queue as the time filler. In Study 2, conducted with 83 participants who experienced a simulated telephone wait experience, sense of progress in the queue rather than perceived waiting time mediated the relationship between telephone waiting time filler and caller reactions. The findings provide insight for the management and design of telephone queues, as well as theoretical insight into critical cognitive processes that underlie telephone waiting, opening up an important new research agenda. (c) 2007 APA, all rights reserved.

  10. Store operation with conditional push of a tag value to a queue

    DOEpatents

    Heidelberger, Philip; Steinmacher-Burow, Burkhard

    2015-07-28

    According to one embodiment, a method for a store operation with a conditional push of a tag value to a queue is provided. The method includes configuring a queue that is accessible by an application, setting a value at an address in a memory device including a memory and a controller, receiving a request for an operation using the value at the address and performing the operation. The method also includes the controller writing a result of the operation to the address, thus changing the value at the address, the controller determining if the result of the operation meets a condition and the controller pushing a tag value to the queue based on the condition being met, where the tag value in the queue indicates to the application that the condition is met.

  11. A High-Throughput Processor for Flight Control Research Using Small UAVs

    NASA Technical Reports Server (NTRS)

    Klenke, Robert H.; Sleeman, W. C., IV; Motter, Mark A.

    2006-01-01

    There are numerous autopilot systems that are commercially available for small (<100 lbs) UAVs. However, they all share several key disadvantages for conducting aerodynamic research, chief amongst which is the fact that most utilize older, slower, 8- or 16-bit microcontroller technologies. This paper describes the development and testing of a flight control system (FCS) for small UAV s based on a modern, high throughput, embedded processor. In addition, this FCS platform contains user-configurable hardware resources in the form of a Field Programmable Gate Array (FPGA) that can be used to implement custom, application-specific hardware. This hardware can be used to off-load routine tasks such as sensor data collection, from the FCS processor thereby further increasing the computational throughput of the system.

  12. Computational steering of GEM based detector simulations

    NASA Astrophysics Data System (ADS)

    Sheharyar, Ali; Bouhali, Othmane

    2017-10-01

    Gas based detector R&D relies heavily on full simulation of detectors and their optimization before final prototypes can be built and tested. These simulations in particular those with complex scenarios such as those involving high detector voltages or gas with larger gains are computationally intensive may take several days or weeks to complete. These long-running simulations usually run on the high-performance computers in batch mode. If the results lead to unexpected behavior, then the simulation might be rerun with different parameters. However, the simulations (or jobs) may have to wait in a queue until they get a chance to run again because the supercomputer is a shared resource that maintains a queue of other user programs as well and executes them as time and priorities permit. It may result in inefficient resource utilization and increase in the turnaround time for the scientific experiment. To overcome this issue, the monitoring of the behavior of a simulation, while it is running (or live), is essential. In this work, we employ the computational steering technique by coupling the detector simulations with a visualization package named VisIt to enable the exploration of the live data as it is produced by the simulation.

  13. A pervasive parallel framework for visualization: final report for FWP 10-014707

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Moreland, Kenneth D.

    2014-01-01

    We are on the threshold of a transformative change in the basic architecture of highperformance computing. The use of accelerator processors, characterized by large core counts, shared but asymmetrical memory, and heavy thread loading, is quickly becoming the norm in high performance computing. These accelerators represent significant challenges in updating our existing base of software. An intrinsic problem with this transition is a fundamental programming shift from message passing processes to much more fine thread scheduling with memory sharing. Another problem is the lack of stability in accelerator implementation; processor and compiler technology is currently changing rapidly. This report documentsmore » the results of our three-year ASCR project to address these challenges. Our project includes the development of the Dax toolkit, which contains the beginnings of new algorithms for a new generation of computers and the underlying infrastructure to rapidly prototype and build further algorithms as necessary.« less

  14. 77 FR 15095 - Combined Notice of Filings #1

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-14

    .... 3250; Queue No. W2-091 to be effective 2/14/2012. Filed Date: 3/7/12. Accession Number: 20120307-5041.... Description: Original Service Agreement No. 3249; Queue No. W2-088 effective 2/14/2012 [initial submission description misidentified as No. 3250; Queue No. W2-091. Filed Date: 3/7/12. Accession Number: 20120307-5051...

  15. Queue observing at the Observatoire du Mont-Mégantic 1.6-m telescope

    NASA Astrophysics Data System (ADS)

    Artigau, Étienne; Lamontagne, Robert; Doyon, René; Malo, Lison

    2010-07-01

    Queue planning of observation and service observing are generally seen as specific to large, world-class, astronomical observatories that draw proposal from a large community. One of the common grievance, justified or not, against queue planning and service observing is the fear of training a generation of astronomers without hands-on observing experience. At the Observatoire du Mont-Mégantic (OMM) 1.6-m telescope, we are developing a student-run service observing program. Queue planning and service observing are used as training tools to expose students to a variety of scientific project and instruments beyond what they would normally use for their own research project. The queue mode at the OMM specifically targets relatively shallow observations that can be completed in less than a few hours and are too short to justify a multi-night classical observing run.

  16. Study on queueing behavior in pedestrian evacuation by extended cellular automata model

    NASA Astrophysics Data System (ADS)

    Hu, Jun; You, Lei; Zhang, Hong; Wei, Juan; Guo, Yangyong

    2018-01-01

    This paper proposes a pedestrian evacuation model for effective simulation of evacuation efficiency based on extended cellular automata. In the model, pedestrians' momentary transition probability to a target position is defined in terms of the floor field and queueing time, and the critical time is defined as the waiting time threshold in a queue. Queueing time and critical time are derived using Fractal Brownian Motion through analysis of pedestrian arrival characteristics. Simulations using the platform and actual evacuations were conducted to study the relationships among system evacuation time, average system velocity, pedestrian density, flow rate, and critical time. The results demonstrate that at low pedestrian density, evacuation efficiency can be improved through adoption of the shortest route strategy, and critical time has an inverse relationship with average system velocity. Conversely, at higher pedestrian densities, it is better to adopt the shortest queueing time strategy, and critical time is inversely related to flow rate.

  17. Unclassified Information Sharing and Coordination in Security, Stabilization, Transition and Reconstruction Efforts

    DTIC Science & Technology

    2008-03-01

    is implemented using the Drupal (2007) content management system (CMS) and many of the baseline information sharing and collaboration tools have...been contributed through the Dru- pal open source community. Drupal is a very modular open source software written in PHP hypertext processor...needed to suit the particular problem domain. While other frameworks have the potential to provide similar advantages (“Ruby,” 2007), Drupal was

  18. A cache-aided multiprocessor rollback recovery scheme

    NASA Technical Reports Server (NTRS)

    Wu, Kun-Lung; Fuchs, W. Kent

    1989-01-01

    This paper demonstrates how previous uniprocessor cache-aided recovery schemes can be applied to multiprocessor architectures, for recovering from transient processor failures, utilizing private caches and a global shared memory. As with cache-aided uniprocessor recovery, the multiprocessor cache-aided recovery scheme of this paper can be easily integrated into standard bus-based snoopy cache coherence protocols. A consistent shared memory state is maintained without the necessity of global check-pointing.

  19. Initial Performance Results on IBM POWER6

    NASA Technical Reports Server (NTRS)

    Saini, Subbash; Talcott, Dale; Jespersen, Dennis; Djomehri, Jahed; Jin, Haoqiang; Mehrotra, Piysuh

    2008-01-01

    The POWER5+ processor has a faster memory bus than that of the previous generation POWER5 processor (533 MHz vs. 400 MHz), but the measured per-core memory bandwidth of the latter is better than that of the former (5.7 GB/s vs. 4.3 GB/s). The reason for this is that in the POWER5+, the two cores on the chip share the L2 cache, L3 cache and memory bus. The memory controller is also on the chip and is shared by the two cores. This serializes the path to memory. For consistently good performance on a wide range of applications, the performance of the processor, the memory subsystem, and the interconnects (both latency and bandwidth) should be balanced. Recognizing this, IBM has designed the Power6 processor so as to avoid the bottlenecks due to the L2 cache, memory controller and buffer chips of the POWER5+. Unlike the POWER5+, each core in the POWER6 has its own L2 cache (4 MB - double that of the Power5+), memory controller and buffer chips. Each core in the POWER6 runs at 4.7 GHz instead of 1.9 GHz in POWER5+. In this paper, we evaluate the performance of a dual-core Power6 based IBM p6-570 system, and we compare its performance with that of a dual-core Power5+ based IBM p575+ system. In this evaluation, we have used the High- Performance Computing Challenge (HPCC) benchmarks, NAS Parallel Benchmarks (NPB), and four real-world applications--three from computational fluid dynamics and one from climate modeling.

  20. Shared versus distributed memory multiprocessors

    NASA Technical Reports Server (NTRS)

    Jordan, Harry F.

    1991-01-01

    The question of whether multiprocessors should have shared or distributed memory has attracted a great deal of attention. Some researchers argue strongly for building distributed memory machines, while others argue just as strongly for programming shared memory multiprocessors. A great deal of research is underway on both types of parallel systems. Special emphasis is placed on systems with a very large number of processors for computation intensive tasks and considers research and implementation trends. It appears that the two types of systems will likely converge to a common form for large scale multiprocessors.

  1. A robust and high-performance queue management controller for large round trip time networks

    NASA Astrophysics Data System (ADS)

    Khoshnevisan, Ladan; Salmasi, Farzad R.

    2016-05-01

    Congestion management for transmission control protocol is of utmost importance to prevent packet loss within a network. This necessitates strategies for active queue management. The most applied active queue management strategies have their inherent disadvantages which lead to suboptimal performance and even instability in the case of large round trip time and/or external disturbance. This paper presents an internal model control robust queue management scheme with two degrees of freedom in order to restrict the undesired effects of large and small round trip time and parameter variations in the queue management. Conventional approaches such as proportional integral and random early detection procedures lead to unstable behaviour due to large delay. Moreover, internal model control-Smith scheme suffers from large oscillations due to the large round trip time. On the other hand, other schemes such as internal model control-proportional integral and derivative show excessive sluggish performance for small round trip time values. To overcome these shortcomings, we introduce a system entailing two individual controllers for queue management and disturbance rejection, simultaneously. Simulation results based on Matlab/Simulink and also Network Simulator 2 (NS2) demonstrate the effectiveness of the procedure and verify the analytical approach.

  2. The congestion control algorithm based on queue management of each node in mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Wei, Yifei; Chang, Lin; Wang, Yali; Wang, Gaoping

    2016-12-01

    This paper proposes an active queue management mechanism, considering the node's own ability and its importance in the network to set the queue threshold. As the network load increases, local congestion of mobile ad hoc network may lead to network performance degradation, hot node's energy consumption increase even failure. If small energy nodes congested because of forwarding data packets, then when it is used as the source node will cause a lot of packet loss. This paper proposes an active queue management mechanism, considering the node's own ability and its importance in the network to set the queue threshold. Controlling nodes buffer queue in different levels of congestion area probability by adjusting the upper limits and lower limits, thus nodes can adjust responsibility of forwarding data packets according to their own situation. The proposed algorithm will slow down the send rate hop by hop along the data package transmission direction from congestion node to source node so that to prevent further congestion from the source node. The simulation results show that, the algorithm can better play the data forwarding ability of strong nodes, protect the weak nodes, can effectively alleviate the network congestion situation.

  3. Propagation speed of a starting wave in a queue of pedestrians.

    PubMed

    Tomoeda, Akiyasu; Yanagisawa, Daichi; Imamura, Takashi; Nishinari, Katsuhiro

    2012-09-01

    The propagation speed of a starting wave, which is a wave of people's successive reactions in the relaxation process of a queue, has an essential role for pedestrians and vehicles to achieve smooth movement. For example, a queue of vehicles with appropriate headway (or density) alleviates traffic jams since the delay of reaction to start is minimized. In this paper, we have investigated the fundamental relation between the propagation speed of a starting wave and the initial density by both our mathematical model built on the stochastic cellular automata and experimental measurements. Analysis of our mathematical model implies that the relation is characterized by the power law αρ-β (β≠1), and the experimental results verify this feature. Moreover, when the starting wave is characterized by the power law (β>1), we have revealed the existence of optimal density, where the required time, i.e., the sum of the waiting time until the starting wave reaches the last pedestrian in a queue and his/her travel time to pass the head position of the initial queue, is minimized. This optimal density inevitably plays a significant role in achieving a smooth movement of crowds and vehicles in a queue.

  4. Control of Networked Traffic Flow Distribution - A Stochastic Distribution System Perspective

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Hong; Aziz, H M Abdul; Young, Stan

    Networked traffic flow is a common scenario for urban transportation, where the distribution of vehicle queues either at controlled intersections or highway segments reflect the smoothness of the traffic flow in the network. At signalized intersections, the traffic queues are controlled by traffic signal control settings and effective traffic lights control would realize both smooth traffic flow and minimize fuel consumption. Funded by the Energy Efficient Mobility Systems (EEMS) program of the Vehicle Technologies Office of the US Department of Energy, we performed a preliminary investigation on the modelling and control framework in context of urban network of signalized intersections.more » In specific, we developed a recursive input-output traffic queueing models. The queue formation can be modeled as a stochastic process where the number of vehicles entering each intersection is a random number. Further, we proposed a preliminary B-Spline stochastic model for a one-way single-lane corridor traffic system based on theory of stochastic distribution control.. It has been shown that the developed stochastic model would provide the optimal probability density function (PDF) of the traffic queueing length as a dynamic function of the traffic signal setting parameters. Based upon such a stochastic distribution model, we have proposed a preliminary closed loop framework on stochastic distribution control for the traffic queueing system to make the traffic queueing length PDF follow a target PDF that potentially realizes the smooth traffic flow distribution in a concerned corridor.« less

  5. Scalability of a Low-Cost Multi-Teraflop Linux Cluster for High-End Classical Atomistic and Quantum Mechanical Simulations

    NASA Technical Reports Server (NTRS)

    Kikuchi, Hideaki; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya; Shimojo, Fuyuki; Saini, Subhash

    2003-01-01

    Scalability of a low-cost, Intel Xeon-based, multi-Teraflop Linux cluster is tested for two high-end scientific applications: Classical atomistic simulation based on the molecular dynamics method and quantum mechanical calculation based on the density functional theory. These scalable parallel applications use space-time multiresolution algorithms and feature computational-space decomposition, wavelet-based adaptive load balancing, and spacefilling-curve-based data compression for scalable I/O. Comparative performance tests are performed on a 1,024-processor Linux cluster and a conventional higher-end parallel supercomputer, 1,184-processor IBM SP4. The results show that the performance of the Linux cluster is comparable to that of the SP4. We also study various effects, such as the sharing of memory and L2 cache among processors, on the performance.

  6. A Queueing Model for Supervisory Control of Unmanned Autonomous Vehicles

    DTIC Science & Technology

    2013-09-01

    Autonomous Vehicles Joseph DiVita, PhD Robert L. Morris Maria Olinda Rodas SSC Pacific Approved...298 (Rev. 8/98) Prescribed by ANSI Std. Z39.18 09–2013 Final A Queueing Model for Supervisory Control of Unmanned Autonomous Vehicles Joseph...Mission Area: Command and Control, Queueing Model; Supervisory Control; Unmanned Autonomous Vehicles M. O. Rodas U U U U 38 (619)

  7. Multi-core processing and scheduling performance in CMS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hernandez, J. M.; Evans, D.; Foulkes, S.

    2012-01-01

    Commodity hardware is going many-core. We might soon not be able to satisfy the job memory needs per core in the current single-core processing model in High Energy Physics. In addition, an ever increasing number of independent and incoherent jobs running on the same physical hardware not sharing resources might significantly affect processing performance. It will be essential to effectively utilize the multi-core architecture. CMS has incorporated support for multi-core processing in the event processing framework and the workload management system. Multi-core processing jobs share common data in memory, such us the code libraries, detector geometry and conditions data, resultingmore » in a much lower memory usage than standard single-core independent jobs. Exploiting this new processing model requires a new model in computing resource allocation, departing from the standard single-core allocation for a job. The experiment job management system needs to have control over a larger quantum of resource since multi-core aware jobs require the scheduling of multiples cores simultaneously. CMS is exploring the approach of using whole nodes as unit in the workload management system where all cores of a node are allocated to a multi-core job. Whole-node scheduling allows for optimization of the data/workflow management (e.g. I/O caching, local merging) but efficient utilization of all scheduled cores is challenging. Dedicated whole-node queues have been setup at all Tier-1 centers for exploring multi-core processing workflows in CMS. We present the evaluation of the performance scheduling and executing multi-core workflows in whole-node queues compared to the standard single-core processing workflows.« less

  8. Practical use of a word processor in a histopathology laboratory.

    PubMed Central

    Briggs, J C; Ibrahim, N B; Mackintosh, I; Norris, D

    1982-01-01

    Some of the facilities available with a commercially purchased word processing program, linked to a DEC PDP 11/23 computer are described, together with an account of the practical histopathological use. The system is based on a share of the computer with a Clinical Chemistry Department. Development was time-consuming and required the constant availability of the Department of Physics. However, once working, considerable saving in secretarial time has resulted and a number of projects have been started which would not have been contemplated without the use of the word processor and its linked computer. Images PMID:7068906

  9. Reconfigurable tree architectures using subtree oriented fault tolerance

    NASA Technical Reports Server (NTRS)

    Lowrie, Matthew B.

    1987-01-01

    An approach to the design of reconfigurable tree architecture is presented in which spare processors are allocated at the leaves. The approach is unique in that spares are associated with subtrees and sharing of spares between these subtrees can occur. The Subtree Oriented Fault Tolerance (SOFT) approach is more reliable than previous approaches capable of tolerating link and switch failures for both single chip and multichip tree implementations while reducing redundancy in terms of both spare processors and links. VLSI layout is 0(n) for binary trees and is directly extensible to N-ary trees and fault tolerance through performance degradation.

  10. Parallel Gaussian elimination of a block tridiagonal matrix using multiple microcomputers

    NASA Technical Reports Server (NTRS)

    Blech, Richard A.

    1989-01-01

    The solution of a block tridiagonal matrix using parallel processing is demonstrated. The multiprocessor system on which results were obtained and the software environment used to program that system are described. Theoretical partitioning and resource allocation for the Gaussian elimination method used to solve the matrix are discussed. The results obtained from running 1, 2 and 3 processor versions of the block tridiagonal solver are presented. The PASCAL source code for these solvers is given in the appendix, and may be transportable to other shared memory parallel processors provided that the synchronization outlines are reproduced on the target system.

  11. Processor Would Find Best Paths On Map

    NASA Technical Reports Server (NTRS)

    Eberhardt, Silvio P.

    1990-01-01

    Proposed very-large-scale integrated (VLSI) circuit image-data processor finds path of least cost from specified origin to any destination on map. Cost of traversal assigned to each picture element of map. Path of least cost from originating picture element to every other picture element computed as path that preserves as much as possible of signal transmitted by originating picture element. Dedicated microprocessor at each picture element stores cost of traversal and performs its share of computations of paths of least cost. Least-cost-path problem occurs in research, military maneuvers, and in planning routes of vehicles.

  12. Research on a Queue Scheduling Algorithm in Wireless Communications Network

    NASA Astrophysics Data System (ADS)

    Yang, Wenchuan; Hu, Yuanmei; Zhou, Qiancai

    This paper proposes a protocol QS-CT, Queue Scheduling Mechanism based on Multiple Access in Ad hoc net work, which adds queue scheduling mechanism to RTS-CTS-DATA using multiple access protocol. By endowing different queues different scheduling mechanisms, it makes networks access to the channel much more fairly and effectively, and greatly enhances the performance. In order to observe the final performance of the network with QS-CT protocol, we simulate it and compare it with MACA/C-T without QS-CT protocol. Contrast to MACA/C-T, the simulation result shows that QS-CT has greatly improved the throughput, delay, rate of packets' loss and other key indicators.

  13. Predicting clinical image delivery time by monitoring PACS queue behavior.

    PubMed

    King, Nelson E; Documet, Jorge; Liu, Brent

    2006-01-01

    The expectation of rapid image retrieval from PACS users contributes to increased information technology (IT) infrastructure investments to increase performance as well as continuing demands upon PACS administrators to respond to "slow" system performance. The ability to provide predicted delivery times to a PACS user may curb user expectations for "fastest" response especially during peak hours. This, in turn, could result in a PACS infrastructure tailored to more realistic performance demands. A PACS with a stand-alone architecture under peak load typically holds study requests in a queue until the DICOM C-Move command can take place. We investigate the contents of a stand-alone architecture PACS RetrieveSend queue and identified parameters and behaviors that enable a more accurate prediction of delivery time. A prediction algorithm for studies delayed in a stand-alone PACS queue can be extendible to other potential bottlenecks such as long-term storage archives. Implications of a queue monitor in other PACS architectures are also discussed.

  14. British Columbia sends patients to Seattle for coronary artery surgery. Bypassing the queue in Canada.

    PubMed

    Katz, S J; Mizgala, H F; Welch, H G

    1991-08-28

    Concern about waiting lists for elective procedures has become a highly visible challenge to the universal health insurance program in Canada. In response to lengthening queues for patients waiting for cardiac surgery, British Columbia made contracts with four Seattle hospitals to send a total of 200 patients for coronary artery bypass surgery. This article examines the cause of the queue for cardiac surgery in British Columbia and the events that led to outside contracting. Global hospital budgets and restrictions on capital expansion have limited hospital capacity for cardiac surgery. This constrained supply, combined with periodic shortages in critical care nurses and cardiac perfusion technologists, has resulted in a rapid increase in the waiting list. Reducing wide variations in the lengths of queues for individual surgeons may afford an opportunity to reduce long waits. While the patient queue for cardiac surgery has sparked a public debate about budget limits and health care needs, its clinical impact remains uncertain.

  15. Queued History based Mediator Identification for an Incentive Attached peer to peer Electronic Coupon System

    NASA Astrophysics Data System (ADS)

    Shojima, Taiki; Ikkai, Yoshitomo; Komoda, Norihisa

    An incentive attached peer to peer (P2P) electronic coupon system is proposed in which users forward e-coupons to potential users by providing incentives to those mediators. A service provider needs to acquire distribution history for incentive payment by recording UserIDs (UIDs) in the e-coupons, since this system is intended for pure P2P environment. This causes problems of dishonestly altering distribution history. In order to solve such problems, distribution history is realized in a couple of queues structure. They are the UID queue, and the public key queue. Each element of the UID queue at the initial state consists of index, a secret key, and a digital signature. In recording one's UID, the encrypted UID is enqueued to the UID queue with a new digital signature created by a secret key of the dequeued element, so that each UID cannot be altered. The public key queue provides the functionality of validating digital signatures on mobile devices. This method makes it possible both each UID and sequence of them to be certificated. The availability of the method is evaluated by quantifying risk reduction using Fault Tree Analysis (FTA). And it's recognized that the method is better than common encryption methods.

  16. Social stability and helping in small animal societies

    PubMed Central

    Field, Jeremy; Cant, Michael A.

    2009-01-01

    In primitively eusocial societies, all individuals can potentially reproduce independently. The key fact that we focus on in this paper is that individuals in such societies instead often queue to inherit breeding positions. Queuing leads to systematic differences in expected future fitness. We first discuss the implications this has for variation in behaviour. For example, because helpers nearer to the front of the queue have more to lose, they should work less hard to rear the dominant's offspring. However, higher rankers may be more aggressive than low rankers, even if they risk injury in the process, if aggression functions to maintain or enhance queue position. Second, we discuss how queuing rules may be enforced through hidden threats that rarely have to be carried out. In fishes, rule breakers face the threat of eviction from the group. In contrast, subordinate paper wasps are not injured or evicted during escalated challenges against the dominant, perhaps because they are more valuable to the dominant. We discuss evidence that paper-wasp dominants avoid escalated conflicts by ceding reproduction to subordinates. Queuing rules appear usually to be enforced by individuals adjacent in the queue rather than by dominants. Further manipulative studies are required to reveal mechanisms underlying queue stability and to elucidate what determines queue position in the first place. PMID:19805426

  17. BioQueue: a novel pipeline framework to accelerate bioinformatics analysis.

    PubMed

    Yao, Li; Wang, Heming; Song, Yuanyuan; Sui, Guangchao

    2017-10-15

    With the rapid development of Next-Generation Sequencing, a large amount of data is now available for bioinformatics research. Meanwhile, the presence of many pipeline frameworks makes it possible to analyse these data. However, these tools concentrate mainly on their syntax and design paradigms, and dispatch jobs based on users' experience about the resources needed by the execution of a certain step in a protocol. As a result, it is difficult for these tools to maximize the potential of computing resources, and avoid errors caused by overload, such as memory overflow. Here, we have developed BioQueue, a web-based framework that contains a checkpoint before each step to automatically estimate the system resources (CPU, memory and disk) needed by the step and then dispatch jobs accordingly. BioQueue possesses a shell command-like syntax instead of implementing a new script language, which means most biologists without computer programming background can access the efficient queue system with ease. BioQueue is freely available at https://github.com/liyao001/BioQueue. The extensive documentation can be found at http://bioqueue.readthedocs.io. li_yao@outlook.com or gcsui@nefu.edu.cn. Supplementary data are available at Bioinformatics online. © The Author (2017). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com

  18. Queues on a Dynamically Evolving Graph

    NASA Astrophysics Data System (ADS)

    Mandjes, Michel; Starreveld, Nicos J.; Bekker, René

    2018-04-01

    This paper considers a population process on a dynamically evolving graph, which can be alternatively interpreted as a queueing network. The queues are of infinite-server type, entailing that at each node all customers present are served in parallel. The links that connect the queues have the special feature that they are unreliable, in the sense that their status alternates between `up' and `down'. If a link between two nodes is down, with a fixed probability each of the clients attempting to use that link is lost; otherwise the client remains at the origin node and reattempts using the link (and jumps to the destination node when it finds the link restored). For these networks we present the following results: (a) a system of coupled partial differential equations that describes the joint probability generating function corresponding to the queues' time-dependent behavior (and a system of ordinary differential equations for its stationary counterpart), (b) an algorithm to evaluate the (time-dependent and stationary) moments, and procedures to compute user-perceived performance measures which facilitate the quantification of the impact of the links' outages, (c) a diffusion limit for the joint queue length process. We include explicit results for a series relevant special cases, such as tandem networks and symmetric fully connected networks.

  19. Application of Queueing Theory to the Analysis of Changes in Outpatients' Waiting Times in Hospitals Introducing EMR

    PubMed Central

    Cho, Kyoung Won; Kim, Seong Min; Chae, Young Moon

    2017-01-01

    Objectives This research used queueing theory to analyze changes in outpatients' waiting times before and after the introduction of Electronic Medical Record (EMR) systems. Methods We focused on the exact drawing of two fundamental parameters for queueing analysis, arrival rate (λ) and service rate (µ), from digital data to apply queueing theory to the analysis of outpatients' waiting times. We used outpatients' reception times and consultation finish times to calculate the arrival and service rates, respectively. Results Using queueing theory, we could calculate waiting time excluding distorted values from the digital data and distortion factors, such as arrival before the hospital open time, which occurs frequently in the initial stage of a queueing system. We analyzed changes in outpatients' waiting times before and after the introduction of EMR using the methodology proposed in this paper, and found that the outpatients' waiting time decreases after the introduction of EMR. More specifically, the outpatients' waiting times in the target public hospitals have decreased by rates in the range between 44% and 78%. Conclusions It is possible to analyze waiting times while minimizing input errors and limitations influencing consultation procedures if we use digital data and apply the queueing theory. Our results verify that the introduction of EMR contributes to the improvement of patient services by decreasing outpatients' waiting time, or by increasing efficiency. It is also expected that our methodology or its expansion could contribute to the improvement of hospital service by assisting the identification and resolution of bottlenecks in the outpatient consultation process. PMID:28261529

  20. Application of Queueing Theory to the Analysis of Changes in Outpatients' Waiting Times in Hospitals Introducing EMR.

    PubMed

    Cho, Kyoung Won; Kim, Seong Min; Chae, Young Moon; Song, Yong Uk

    2017-01-01

    This research used queueing theory to analyze changes in outpatients' waiting times before and after the introduction of Electronic Medical Record (EMR) systems. We focused on the exact drawing of two fundamental parameters for queueing analysis, arrival rate (λ) and service rate (µ), from digital data to apply queueing theory to the analysis of outpatients' waiting times. We used outpatients' reception times and consultation finish times to calculate the arrival and service rates, respectively. Using queueing theory, we could calculate waiting time excluding distorted values from the digital data and distortion factors, such as arrival before the hospital open time, which occurs frequently in the initial stage of a queueing system. We analyzed changes in outpatients' waiting times before and after the introduction of EMR using the methodology proposed in this paper, and found that the outpatients' waiting time decreases after the introduction of EMR. More specifically, the outpatients' waiting times in the target public hospitals have decreased by rates in the range between 44% and 78%. It is possible to analyze waiting times while minimizing input errors and limitations influencing consultation procedures if we use digital data and apply the queueing theory. Our results verify that the introduction of EMR contributes to the improvement of patient services by decreasing outpatients' waiting time, or by increasing efficiency. It is also expected that our methodology or its expansion could contribute to the improvement of hospital service by assisting the identification and resolution of bottlenecks in the outpatient consultation process.

  1. Performance Evaluation and Modeling Techniques for Parallel Processors. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Dimpsey, Robert Tod

    1992-01-01

    In practice, the performance evaluation of supercomputers is still substantially driven by singlepoint estimates of metrics (e.g., MFLOPS) obtained by running characteristic benchmarks or workloads. With the rapid increase in the use of time-shared multiprogramming in these systems, such measurements are clearly inadequate. This is because multiprogramming and system overhead, as well as other degradations in performance due to time varying characteristics of workloads, are not taken into account. In multiprogrammed environments, multiple jobs and users can dramatically increase the amount of system overhead and degrade the performance of the machine. Performance techniques, such as benchmarking, which characterize performance on a dedicated machine ignore this major component of true computer performance. Due to the complexity of analysis, there has been little work done in analyzing, modeling, and predicting the performance of applications in multiprogrammed environments. This is especially true for parallel processors, where the costs and benefits of multi-user workloads are exacerbated. While some may claim that the issue of multiprogramming is not a viable one in the supercomputer market, experience shows otherwise. Even in recent massively parallel machines, multiprogramming is a key component. It has even been claimed that a partial cause of the demise of the CM2 was the fact that it did not efficiently support time-sharing. In the same paper, Gordon Bell postulates that, multicomputers will evolve to multiprocessors in order to support efficient multiprogramming. Therefore, it is clear that parallel processors of the future will be required to offer the user a time-shared environment with reasonable response times for the applications. In this type of environment, the most important performance metric is the completion of response time of a given application. However, there are a few evaluation efforts addressing this issue.

  2. Efficient irregular wavefront propagation algorithms on Intel® Xeon Phi™

    PubMed Central

    Gomes, Jeremias M.; Teodoro, George; de Melo, Alba; Kong, Jun; Kurc, Tahsin; Saltz, Joel H.

    2016-01-01

    We investigate the execution of the Irregular Wavefront Propagation Pattern (IWPP), a fundamental computing structure used in several image analysis operations, on the Intel® Xeon Phi™ co-processor. An efficient implementation of IWPP on the Xeon Phi is a challenging problem because of IWPP’s irregularity and the use of atomic instructions in the original IWPP algorithm to resolve race conditions. On the Xeon Phi, the use of SIMD and vectorization instructions is critical to attain high performance. However, SIMD atomic instructions are not supported. Therefore, we propose a new IWPP algorithm that can take advantage of the supported SIMD instruction set. We also evaluate an alternate storage container (priority queue) to track active elements in the wavefront in an effort to improve the parallel algorithm efficiency. The new IWPP algorithm is evaluated with Morphological Reconstruction and Imfill operations as use cases. Our results show performance improvements of up to 5.63× on top of the original IWPP due to vectorization. Moreover, the new IWPP achieves speedups of 45.7× and 1.62×, respectively, as compared to efficient CPU and GPU implementations. PMID:27298591

  3. Efficient irregular wavefront propagation algorithms on Intel® Xeon Phi™.

    PubMed

    Gomes, Jeremias M; Teodoro, George; de Melo, Alba; Kong, Jun; Kurc, Tahsin; Saltz, Joel H

    2015-10-01

    We investigate the execution of the Irregular Wavefront Propagation Pattern (IWPP), a fundamental computing structure used in several image analysis operations, on the Intel ® Xeon Phi ™ co-processor. An efficient implementation of IWPP on the Xeon Phi is a challenging problem because of IWPP's irregularity and the use of atomic instructions in the original IWPP algorithm to resolve race conditions. On the Xeon Phi, the use of SIMD and vectorization instructions is critical to attain high performance. However, SIMD atomic instructions are not supported. Therefore, we propose a new IWPP algorithm that can take advantage of the supported SIMD instruction set. We also evaluate an alternate storage container (priority queue) to track active elements in the wavefront in an effort to improve the parallel algorithm efficiency. The new IWPP algorithm is evaluated with Morphological Reconstruction and Imfill operations as use cases. Our results show performance improvements of up to 5.63 × on top of the original IWPP due to vectorization. Moreover, the new IWPP achieves speedups of 45.7 × and 1.62 × , respectively, as compared to efficient CPU and GPU implementations.

  4. High order parallel numerical schemes for solving incompressible flows

    NASA Technical Reports Server (NTRS)

    Lin, Avi; Milner, Edward J.; Liou, May-Fun; Belch, Richard A.

    1992-01-01

    The use of parallel computers for numerically solving flow fields has gained much importance in recent years. This paper introduces a new high order numerical scheme for computational fluid dynamics (CFD) specifically designed for parallel computational environments. A distributed MIMD system gives the flexibility of treating different elements of the governing equations with totally different numerical schemes in different regions of the flow field. The parallel decomposition of the governing operator to be solved is the primary parallel split. The primary parallel split was studied using a hypercube like architecture having clusters of shared memory processors at each node. The approach is demonstrated using examples of simple steady state incompressible flows. Future studies should investigate the secondary split because, depending on the numerical scheme that each of the processors applies and the nature of the flow in the specific subdomain, it may be possible for a processor to seek better, or higher order, schemes for its particular subcase.

  5. Efficient Sorting on the Tilera Manycore Architecture

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Morari, Alessandro; Tumeo, Antonino; Villa, Oreste

    e present an efficient implementation of the radix sort algo- rithm for the Tilera TILEPro64 processor. The TILEPro64 is one of the first successful commercial manycore processors. It is com- posed of 64 tiles interconnected through multiple fast Networks- on-chip and features a fully coherent, shared distributed cache. The architecture has a large degree of flexibility, and allows various optimization strategies. We describe how we mapped the algorithm to this architecture. We present an in-depth analysis of the optimizations for each phase of the algorithm with respect to the processor’s sustained performance. We discuss the overall throughput reached by ourmore » radix sort implementation (up to 132 MK/s) and show that it provides comparable or better performance-per-watt with respect to state-of-the art implemen- tations on x86 processors and graphic processing units.« less

  6. Three-Dimensional High-Lift Analysis Using a Parallel Unstructured Multigrid Solver

    NASA Technical Reports Server (NTRS)

    Mavriplis, Dimitri J.

    1998-01-01

    A directional implicit unstructured agglomeration multigrid solver is ported to shared and distributed memory massively parallel machines using the explicit domain-decomposition and message-passing approach. Because the algorithm operates on local implicit lines in the unstructured mesh, special care is required in partitioning the problem for parallel computing. A weighted partitioning strategy is described which avoids breaking the implicit lines across processor boundaries, while incurring minimal additional communication overhead. Good scalability is demonstrated on a 128 processor SGI Origin 2000 machine and on a 512 processor CRAY T3E machine for reasonably fine grids. The feasibility of performing large-scale unstructured grid calculations with the parallel multigrid algorithm is demonstrated by computing the flow over a partial-span flap wing high-lift geometry on a highly resolved grid of 13.5 million points in approximately 4 hours of wall clock time on the CRAY T3E.

  7. Waiting for coronary angiography: is there a clinically ordered queue?

    PubMed

    Hemingway, H; Crook, A M; Feder, G; Dawson, J R; Timmis, A

    2000-03-18

    Among over 3000 patients undergoing coronary angiography in the absence of a formal queue-management system, we found that a-priori urgency scores were strongly associated with waiting times, prevalence of coronary-artery disease, rate of revascularisation, and mortality. These data challenge the widely held assumption that such waiting lists are not clinically ordered; however, the wide variation in waiting times within urgency categories suggests the need for further improvements in clinical queueing.

  8. Cost Comparison of B-1B Non-Mission-Capable Drivers Using Finite Source Queueing with Spares

    DTIC Science & Technology

    2012-09-06

    COMPARISON OF B-1B NON-MISSION-CAPABLE DRIVERS USING FINITE SOURCE QUEUEING WITH SPARES GRADUATE RESEARCH PAPER Presented to the Faculty...step into the lineup making large-number approximations unusable. Instead, a finite source queueing model including spares is incorporated...were reported as flying time accrued since last occurrence. Service time was given in both start-stop format and MX man-hours utilized. Service time was

  9. Multifractal Internet Traffic Model and Active Queue Management

    DTIC Science & Technology

    2003-01-01

    dropped by the Adaptive RED , ssthresh decreases from 64KB to 4KB and the new con- gestion window cwnd is decreased from 8KB to 1KB (Tahoe). The situation...method to predict the queuing behavior of FIFO and RED queues. In order to satisfy a given delay and jitter requirement for real time connections, and to...5.2 Vulnerability of Adaptive RED to Web-mice . . . . . . . . . . . . . 103 5.3 A Parallel Virtual Queues Structure

  10. An agent-based model for queue formation of powered two-wheelers in heterogeneous traffic

    NASA Astrophysics Data System (ADS)

    Lee, Tzu-Chang; Wong, K. I.

    2016-11-01

    This paper presents an agent-based model (ABM) for simulating the queue formation of powered two-wheelers (PTWs) in heterogeneous traffic at a signalized intersection. The main novelty is that the proposed interaction rule describing the position choice behavior of PTWs when queuing in heterogeneous traffic can capture the stochastic nature of the decision making process. The interaction rule is formulated as a multinomial logit model, which is calibrated by using a microscopic traffic trajectory dataset obtained from video footage. The ABM is validated against the survey data for the vehicular trajectory patterns, queuing patterns, queue lengths, and discharge rates. The results demonstrate that the proposed model is capable of replicating the observed queue formation process for heterogeneous traffic.

  11. Cache Sharing and Isolation Tradeoffs in Multicore Mixed-Criticality Systems

    DTIC Science & Technology

    2015-05-01

    of lockdown registers, to provide way-based partitioning. These alternatives are illustrated in Fig. 1 with respect to a quad-core ARM Cortex A9...presented a cache-partitioning scheme that allows multiple tasks to share the same cache partition on a single processor (as we do for Level-A and...sets and determined the fraction that were schedulable on our target hardware platform, the quad-core ARM Cortex A9 machine mentioned earlier, the LLC

  12. Sharing the skies: the Gemini Observatory international time allocation process

    NASA Astrophysics Data System (ADS)

    Margheim, Steven J.

    2016-07-01

    Gemini Observatory serves a diverse community of four partner countries (United States, Canada, Brazil, and Argentina), two hosts (Chile and University of Hawaii), and limited-term partnerships (currently Australia and the Republic of Korea). Observing time is available via multiple opportunities including Large and Long Pro- grams, Fast-turnaround programs, and regular semester queue programs. The slate of programs for observation each semester must be created by merging programs from these multiple, conflicting sources. This paper de- scribes the time allocation process used to schedule the overall science program for the semester, with emphasis on the International Time Allocation Committee and the software applications used.

  13. A Methodology for Distributing the Corporate Database.

    ERIC Educational Resources Information Center

    McFadden, Fred R.

    The trend to distributed processing is being fueled by numerous forces, including advances in technology, corporate downsizing, increasing user sophistication, and acquisitions and mergers. Increasingly, the trend in corporate information systems (IS) departments is toward sharing resources over a network of multiple types of processors, operating…

  14. The Tera Multithreaded Architecture and Unstructured Meshes

    NASA Technical Reports Server (NTRS)

    Bokhari, Shahid H.; Mavriplis, Dimitri J.

    1998-01-01

    The Tera Multithreaded Architecture (MTA) is a new parallel supercomputer currently being installed at San Diego Supercomputing Center (SDSC). This machine has an architecture quite different from contemporary parallel machines. The computational processor is a custom design and the machine uses hardware to support very fine grained multithreading. The main memory is shared, hardware randomized and flat. These features make the machine highly suited to the execution of unstructured mesh problems, which are difficult to parallelize on other architectures. We report the results of a study carried out during July-August 1998 to evaluate the execution of EUL3D, a code that solves the Euler equations on an unstructured mesh, on the 2 processor Tera MTA at SDSC. Our investigation shows that parallelization of an unstructured code is extremely easy on the Tera. We were able to get an existing parallel code (designed for a shared memory machine), running on the Tera by changing only the compiler directives. Furthermore, a serial version of this code was compiled to run in parallel on the Tera by judicious use of directives to invoke the "full/empty" tag bits of the machine to obtain synchronization. This version achieves 212 and 406 Mflop/s on one and two processors respectively, and requires no attention to partitioning or placement of data issues that would be of paramount importance in other parallel architectures.

  15. The relationship between (stigmatizing) views and lay public preferences regarding tuberculosis treatment in the Eastern Cape, South Africa.

    PubMed

    Cramm, Jane M; Nieboer, Anna P

    2011-01-14

    Tuberculosis (TB) and human immune virus/acquired immune deficiency syndrome (HIV/AIDS) stigmas affect public attitudes toward TB treatment and policy. This study examined 'stigmatizing' ideas and the view that 'TB patients should line-up in the chronic illness queue' in relation to preferences and attitudes toward TB treatment. Data were gathered through a survey administered to respondents from 1,020 households in Grahamstown. The survey measured stigmatization surrounding TB and HIV/AIDS, and determined perceptions of respondents whether TB patients should queue with other chronically ill patients. Respondents selected support and treatment options they felt would benefit TB patients. Statistical analysis identified the prevalence of TB and HIV/AIDS stigmas. Logistic regression analyses explored associations between stigmatizing ideas, views regarding TB patients in the chronic illness queue, and attitudes toward support and treatment. Respondents with TB stigmatizing ideas held positive attitudes toward volunteer support, special TB queues, and treatment at clinics; they held negative attitudes toward temporary disability grants, provision of information at work or school, and treatment at the TB hospital. Respondents who felt it beneficial for TB patients to queue with other chronically ill patients conversely held positive attitudes toward provision of porridge and disability grants, and treatment at the TB hospital; they held negative attitudes toward volunteer support, special TB queues, information provision at work or school, and treatment at clinics. These results showed that two varying views related to visibility factors that expose patients to stigmatization (one characterized by TB stigma, the other by the view that TB patients should queue with other chronically ill patients) are associated with opposing attitudes and preferences towards TB treatment. These opposing attitudes complicate treatment outcomes, and suggest that complex behaviors must be taken into account when designing health policy.

  16. The Supermarket Model with Bounded Queue Lengths in Equilibrium

    NASA Astrophysics Data System (ADS)

    Brightwell, Graham; Fairthorne, Marianne; Luczak, Malwina J.

    2018-04-01

    In the supermarket model, there are n queues, each with a single server. Customers arrive in a Poisson process with arrival rate λ n , where λ = λ (n) \\in (0,1) . Upon arrival, a customer selects d=d(n) servers uniformly at random, and joins the queue of a least-loaded server amongst those chosen. Service times are independent exponentially distributed random variables with mean 1. In this paper, we analyse the behaviour of the supermarket model in the regime where λ (n) = 1 - n^{-α } and d(n) = \\lfloor n^β \\rfloor , where α and β are fixed numbers in (0, 1]. For suitable pairs (α , β ) , our results imply that, in equilibrium, with probability tending to 1 as n → ∞, the proportion of queues with length equal to k = \\lceil α /β \\rceil is at least 1-2n^{-α + (k-1)β } , and there are no longer queues. We further show that the process is rapidly mixing when started in a good state, and give bounds on the speed of mixing for more general initial conditions.

  17. Production Task Queue Optimization Based on Multi-Attribute Evaluation for Complex Product Assembly Workshop.

    PubMed

    Li, Lian-Hui; Mo, Rong

    2015-01-01

    The production task queue has a great significance for manufacturing resource allocation and scheduling decision. Man-made qualitative queue optimization method has a poor effect and makes the application difficult. A production task queue optimization method is proposed based on multi-attribute evaluation. According to the task attributes, the hierarchical multi-attribute model is established and the indicator quantization methods are given. To calculate the objective indicator weight, criteria importance through intercriteria correlation (CRITIC) is selected from three usual methods. To calculate the subjective indicator weight, BP neural network is used to determine the judge importance degree, and then the trapezoid fuzzy scale-rough AHP considering the judge importance degree is put forward. The balanced weight, which integrates the objective weight and the subjective weight, is calculated base on multi-weight contribution balance model. The technique for order preference by similarity to an ideal solution (TOPSIS) improved by replacing Euclidean distance with relative entropy distance is used to sequence the tasks and optimize the queue by the weighted indicator value. A case study is given to illustrate its correctness and feasibility.

  18. Production Task Queue Optimization Based on Multi-Attribute Evaluation for Complex Product Assembly Workshop

    PubMed Central

    Li, Lian-hui; Mo, Rong

    2015-01-01

    The production task queue has a great significance for manufacturing resource allocation and scheduling decision. Man-made qualitative queue optimization method has a poor effect and makes the application difficult. A production task queue optimization method is proposed based on multi-attribute evaluation. According to the task attributes, the hierarchical multi-attribute model is established and the indicator quantization methods are given. To calculate the objective indicator weight, criteria importance through intercriteria correlation (CRITIC) is selected from three usual methods. To calculate the subjective indicator weight, BP neural network is used to determine the judge importance degree, and then the trapezoid fuzzy scale-rough AHP considering the judge importance degree is put forward. The balanced weight, which integrates the objective weight and the subjective weight, is calculated base on multi-weight contribution balance model. The technique for order preference by similarity to an ideal solution (TOPSIS) improved by replacing Euclidean distance with relative entropy distance is used to sequence the tasks and optimize the queue by the weighted indicator value. A case study is given to illustrate its correctness and feasibility. PMID:26414758

  19. An efficient 3-dim FFT for plane wave electronic structure calculations on massively parallel machines composed of multiprocessor nodes

    NASA Astrophysics Data System (ADS)

    Goedecker, Stefan; Boulet, Mireille; Deutsch, Thierry

    2003-08-01

    Three-dimensional Fast Fourier Transforms (FFTs) are the main computational task in plane wave electronic structure calculations. Obtaining a high performance on a large numbers of processors is non-trivial on the latest generation of parallel computers that consist of nodes made up of a shared memory multiprocessors. A non-dogmatic method for obtaining high performance for such 3-dim FFTs in a combined MPI/OpenMP programming paradigm will be presented. Exploiting the peculiarities of plane wave electronic structure calculations, speedups of up to 160 and speeds of up to 130 Gflops were obtained on 256 processors.

  20. An MPA-IO interface to HPSS

    NASA Technical Reports Server (NTRS)

    Jones, Terry; Mark, Richard; Martin, Jeanne; May, John; Pierce, Elsie; Stanberry, Linda

    1996-01-01

    This paper describes an implementation of the proposed MPI-IO (Message Passing Interface - Input/Output) standard for parallel I/O. Our system uses third-party transfer to move data over an external network between the processors where it is used and the I/O devices where it resides. Data travels directly from source to destination, without the need for shuffling it among processors or funneling it through a central node. Our distributed server model lets multiple compute nodes share the burden of coordinating data transfers. The system is built on the High Performance Storage System (HPSS), and a prototype version runs on a Meiko CS-2 parallel computer.

  1. Memory access in shared virtual memory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Berrendorf, R.

    1992-01-01

    Shared virtual memory (SVM) is a virtual memory layer with a single address space on top of a distributed real memory on parallel computers. We examine the behavior and performance of SVM running a parallel program with medium-grained, loop-level parallelism on top of it. A simulator for the underlying parallel architecture can be used to examine the behavior of SVM more deeply. The influence of several parameters, such as the number of processors, page size, cold or warm start, and restricted page replication, is studied.

  2. Memory access in shared virtual memory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Berrendorf, R.

    1992-09-01

    Shared virtual memory (SVM) is a virtual memory layer with a single address space on top of a distributed real memory on parallel computers. We examine the behavior and performance of SVM running a parallel program with medium-grained, loop-level parallelism on top of it. A simulator for the underlying parallel architecture can be used to examine the behavior of SVM more deeply. The influence of several parameters, such as the number of processors, page size, cold or warm start, and restricted page replication, is studied.

  3. Compiler-directed cache management in multiprocessors

    NASA Technical Reports Server (NTRS)

    Cheong, Hoichi; Veidenbaum, Alexander V.

    1990-01-01

    The necessity of finding alternatives to hardware-based cache coherence strategies for large-scale multiprocessor systems is discussed. Three different software-based strategies sharing the same goals and general approach are presented. They consist of a simple invalidation approach, a fast selective invalidation scheme, and a version control scheme. The strategies are suitable for shared-memory multiprocessor systems with interconnection networks and a large number of processors. Results of trace-driven simulations conducted on numerical benchmark routines to compare the performance of the three schemes are presented.

  4. Ada Quality and Style: Guidelines for Professional Programmers, Version 02.01.01

    DTIC Science & Technology

    1992-12-01

    47, 78, 79 predicate queue , entry not prioritized, 95 as function name, 22 for boolean object, 21 R preemptive scheduling. 118 race condition. 49...when lower priority tasks are given service while higher priority tasks remain blocked. In the above example, this occurred because entry queues are...from an entry queue 100 Ada QUALITY AND STYLE due to execution of an abort statement as well as expiration of a timed entry call. The use of this

  5. Steady-State Algorithmic Analysis M/M/c Two-Priority Queues with Heterogeneous Rates.

    DTIC Science & Technology

    1981-04-21

    ALGORITHMIC ANALYSIS OF M/M/c TWO-PRIORITY QUEUES WITH HETEROGENEOUS RATES by Douglas R. Miller An algorithm for steady-state analysis of M/M/c nonpreemptive ...practical algorithm for systems involving more than two priority classes. The preemptive case is simpler than the nonpreemptive case; an algorithm for it...priority nonpreemptive queueing system with arrival rates 1 and X2 and service rates V and p42 * The state space can be described as follows. Let xi,j,k be

  6. Convergence of a Queueing System in Heavy Traffic with General Abandonment Distributions

    DTIC Science & Technology

    2010-10-08

    3 in Reiman [27]. We circumvent the use of Reiman’s “Snap-shot Principle” and a comparison result with a non-abandoning queue used in Reed and Ward...4):2606–2650, 2005. 37 [5] R. Atar, A. Mandelbaum, and M. I. Reiman . Scheduling a multi class queue with many exponential servers: asymptotic... Reiman Designing a call center with impatient cus- tomers. Manufacturing and Service Oper. Management, 4(1A):208–227, 2002. [15] J. M. George and J. M

  7. Design and analysis of a model predictive controller for active queue management.

    PubMed

    Wang, Ping; Chen, Hong; Yang, Xiaoping; Ma, Yan

    2012-01-01

    Model predictive (MP) control as a novel active queue management (AQM) algorithm in dynamic computer networks is proposed. According to the predicted future queue length in the data buffer, early packets at the router are dropped reasonably by the MPAQM controller so that the queue length reaches the desired value with minimal tracking error. The drop probability is obtained by optimizing the network performance. Further, randomized algorithms are applied to analyze the robustness of MPAQM successfully, and also to provide the stability domain of systems with uncertain network parameters. The performances of MPAQM are evaluated through a series of simulations in NS2. The simulation results show that the MPAQM algorithm outperforms RED, PI, and REM algorithms in terms of stability, disturbance rejection, and robustness. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

  8. Queueing for healthcare.

    PubMed

    Palvannan, R Kannapiran; Teow, Kiok Liang

    2012-04-01

    Patient queues are prevalent in healthcare and wait time is one measure of access to care. We illustrate Queueing Theory-an analytical tool that has provided many insights to service providers when designing new service systems and managing existing ones. This established theory helps us to quantify the appropriate service capacity to meet the patient demand, balancing system utilization and the patient's wait time. It considers four key factors that affect the patient's wait time: average patient demand, average service rate and the variation in both. We illustrate four basic insights that will be useful for managers and doctors who manage healthcare delivery systems, at hospital or department level. Two examples from local hospitals are shown where we have used queueing models to estimate the service capacity and analyze the impact of capacity configurations, while considering the inherent variation in healthcare.

  9. Queue theory for triangular and weibull arrival distribution models (case study of Banyumanik toll)

    NASA Astrophysics Data System (ADS)

    Sugito; Rahmawati, Rita; Kusuma Wardhani, Jenesia

    2018-05-01

    Queuing is one of the most common phenomena in daily life. Queued also happens on highway during busy time. The Electronic Toll Collection (ETC) was the new system of the Banyumanik toll gate which operates in 2014. Before ETC, Banyumanik toll gate users got regular service (regular toll gate) by paying in cash only. The ETC benefits more than regular service, but automatic toll gate (ETC) users are still few compared to regular toll gate users. To know the effectiveness of substance service, this paper used analysis of queuing system. The research was conducted at Toll Gate Banyumanik with the implementation time on 26-28 December 2016 for Ungaran-Semarang direction, and 29-31 December 2016 for Semarang- Ungaran direction. In one day, observation was done for 11 hours. That was at 07.00 a.m. until 06.00 p.m. There are 4 models of queues at Banyumanik toll gate. Here the four models will be used on the number of arrival and service time. Based on the simulation with Arena, the result showed that queue model regular toll gate in Ugaran-Semarang direction is (Tria/G/3):(GD/∞/∞) and the queue model for automatic toll gate is (G/G/3):(GD/∞/∞). While the queue model for the direction of Semarang-Ungaran regular toll gate is (G/G/3):(GD/∞/∞) and the queue model of automatic toll gate is (Weib/G/3):(GD/∞/∞).

  10. Neuromorphic Computing: A Post-Moore's Law Complementary Architecture

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schuman, Catherine D; Birdwell, John Douglas; Dean, Mark

    2016-01-01

    We describe our approach to post-Moore's law computing with three neuromorphic computing models that share a RISC philosophy, featuring simple components combined with a flexible and programmable structure. We envision these to be leveraged as co-processors, or as data filters to provide in situ data analysis in supercomputing environments.

  11. Expert Systems on Multiprocessor Architectures. Volume 2. Technical Reports

    DTIC Science & Technology

    1991-06-01

    Report RC 12936 (#58037). IBM T. J. Wartson Reiearch Center. July 1987. � Alan Jay Smith. Cache memories. Coniputing Sitrry., 1.1(3): I.3-5:30...basic-shared is an instrument for ashared memory design. The components panels are processor- qload-scrolling-bar-panel, memory-qload-scrolling-bar-panel

  12. Copyright in the Age of Photocopiers, Word Processors, and the Internet

    ERIC Educational Resources Information Center

    Shaw, Marjorie Hodges; Shaw, Brian B.

    2003-01-01

    Widespread digital infringement of the copyrighted material now has made security firms, night-vision goggles, and metal detectors common in movie previews. The current national controversy over peer-to-peer file sharing of music highlights the difficult questions facing colleges and universities as they grapple with dramatic technological…

  13. NQS - NETWORK QUEUING SYSTEM, VERSION 2.0 (UNIX VERSION)

    NASA Technical Reports Server (NTRS)

    Walter, H.

    1994-01-01

    The Network Queuing System, NQS, is a versatile batch and device queuing facility for a single Unix computer or a group of networked computers. With the Unix operating system as a common interface, the user can invoke the NQS collection of user-space programs to move batch and device jobs freely around the different computer hardware tied into the network. NQS provides facilities for remote queuing, request routing, remote status, queue status controls, batch request resource quota limits, and remote output return. This program was developed as part of an effort aimed at tying together diverse UNIX based machines into NASA's Numerical Aerodynamic Simulator Processing System Network. This revision of NQS allows for creating, deleting, adding and setting of complexes that aid in limiting the number of requests to be handled at one time. It also has improved device-oriented queues along with some revision of the displays. NQS was designed to meet the following goals: 1) Provide for the full support of both batch and device requests. 2) Support all of the resource quotas enforceable by the underlying UNIX kernel implementation that are relevant to any particular batch request and its corresponding batch queue. 3) Support remote queuing and routing of batch and device requests throughout the NQS network. 4) Support queue access restrictions through user and group access lists for all queues. 5) Enable networked output return of both output and error files to possibly remote machines. 6) Allow mapping of accounts across machine boundaries. 7) Provide friendly configuration and modification mechanisms for each installation. 8) Support status operations across the network, without requiring a user to log in on remote target machines. 9) Provide for file staging or copying of files for movement to the actual execution machine. To support batch and device requests, NQS v.2 implements three queue types--batch, device and pipe. Batch queues hold and prioritize batch requests; device queues hold and prioritize device requests; pipe queues transport both batch and device requests to other batch, device, or pipe queues at local or remote machines. Unique to batch queues are resource quota limits that restrict the amounts of different resources that a batch request can consume during execution. Unique to each device queue is a set of one or more devices, such as a line printer, to which requests can be sent for execution. Pipe queues have associated destinations to which they route and deliver requests. If the proper destination machine is down or unreachable, pipe queues are able to requeue the request and deliver it later when the destination is available. All NQS network conversations are performed using the Berkeley socket mechanism as ported into the respective vendor kernels. NQS is written in C language. The generic UNIX version (ARC-13179) has been successfully implemented on a variety of UNIX platforms, including Sun3 and Sun4 series computers, SGI IRIS computers running IRIX 3.3, DEC computers running ULTRIX 4.1, AMDAHL computers running UTS 1.3 and 2.1, platforms running BSD 4.3 UNIX. The IBM RS/6000 AIX version (COS-10042) is a vendor port. NQS 2.0 will also communicate with the Cray Research, Inc. and Convex, Inc. versions of NQS. The standard distribution medium for either machine version of NQS 2.0 is a 60Mb, QIC-24, .25 inch streaming magnetic tape cartridge in UNIX tar format. Upon request the generic UNIX version (ARC-13179) can be provided in UNIX tar format on alternate media. Please contact COSMIC to discuss the availability and cost of media to meet your specific needs. An electronic copy of the NQS 2.0 documentation is included on the program media. NQS 2.0 was released in 1991. The IBM RS/6000 port of NQS was developed in 1992. IRIX is a trademark of Silicon Graphics Inc. IRIS is a registered trademark of Silicon Graphics Inc. UNIX is a registered trademark of UNIX System Laboratories Inc. Sun3 and Sun4 are trademarks of Sun Microsystems Inc. DEC and ULTRIX are trademarks of Digital Equipment Corporation.

  14. Memory Network For Distributed Data Processors

    NASA Technical Reports Server (NTRS)

    Bolen, David; Jensen, Dean; Millard, ED; Robinson, Dave; Scanlon, George

    1992-01-01

    Universal Memory Network (UMN) is modular, digital data-communication system enabling computers with differing bus architectures to share 32-bit-wide data between locations up to 3 km apart with less than one millisecond of latency. Makes it possible to design sophisticated real-time and near-real-time data-processing systems without data-transfer "bottlenecks". This enterprise network permits transmission of volume of data equivalent to an encyclopedia each second. Facilities benefiting from Universal Memory Network include telemetry stations, simulation facilities, power-plants, and large laboratories or any facility sharing very large volumes of data. Main hub of UMN is reflection center including smaller hubs called Shared Memory Interfaces.

  15. Fast and Accurate Simulation of the Cray XMT Multithreaded Supercomputer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Villa, Oreste; Tumeo, Antonino; Secchi, Simone

    Irregular applications, such as data mining and analysis or graph-based computations, show unpredictable memory/network access patterns and control structures. Highly multithreaded architectures with large processor counts, like the Cray MTA-1, MTA-2 and XMT, appear to address their requirements better than commodity clusters. However, the research on highly multithreaded systems is currently limited by the lack of adequate architectural simulation infrastructures due to issues such as size of the machines, memory footprint, simulation speed, accuracy and customization. At the same time, Shared-memory MultiProcessors (SMPs) with multi-core processors have become an attractive platform to simulate large scale machines. In this paper, wemore » introduce a cycle-level simulator of the highly multithreaded Cray XMT supercomputer. The simulator runs unmodified XMT applications. We discuss how we tackled the challenges posed by its development, detailing the techniques introduced to make the simulation as fast as possible while maintaining a high accuracy. By mapping XMT processors (ThreadStorm with 128 hardware threads) to host computing cores, the simulation speed remains constant as the number of simulated processors increases, up to the number of available host cores. The simulator supports zero-overhead switching among different accuracy levels at run-time and includes a network model that takes into account contention. On a modern 48-core SMP host, our infrastructure simulates a large set of irregular applications 500 to 2000 times slower than real time when compared to a 128-processor XMT, while remaining within 10\\% of accuracy. Emulation is only from 25 to 200 times slower than real time.« less

  16. Fokker-Planck description for the queue dynamics of large tick stocks.

    PubMed

    Garèche, A; Disdier, G; Kockelkoren, J; Bouchaud, J-P

    2013-09-01

    Motivated by empirical data, we develop a statistical description of the queue dynamics for large tick assets based on a two-dimensional Fokker-Planck (diffusion) equation. Our description explicitly includes state dependence, i.e., the fact that the drift and diffusion depend on the volume present on both sides of the spread. "Jump" events, corresponding to sudden changes of the best limit price, must also be included as birth-death terms in the Fokker-Planck equation. All quantities involved in the equation can be calibrated using high-frequency data on the best quotes. One of our central findings is that the dynamical process is approximately scale invariant, i.e., the only relevant variable is the ratio of the current volume in the queue to its average value. While the latter shows intraday seasonalities and strong variability across stocks and time periods, the dynamics of the rescaled volumes is universal. In terms of rescaled volumes, we found that the drift has a complex two-dimensional structure, which is a sum of a gradient contribution and a rotational contribution, both stable across stocks and time. This drift term is entirely responsible for the dynamical correlations between the ask queue and the bid queue.

  17. Fokker-Planck description for the queue dynamics of large tick stocks

    NASA Astrophysics Data System (ADS)

    Garèche, A.; Disdier, G.; Kockelkoren, J.; Bouchaud, J.-P.

    2013-09-01

    Motivated by empirical data, we develop a statistical description of the queue dynamics for large tick assets based on a two-dimensional Fokker-Planck (diffusion) equation. Our description explicitly includes state dependence, i.e., the fact that the drift and diffusion depend on the volume present on both sides of the spread. “Jump” events, corresponding to sudden changes of the best limit price, must also be included as birth-death terms in the Fokker-Planck equation. All quantities involved in the equation can be calibrated using high-frequency data on the best quotes. One of our central findings is that the dynamical process is approximately scale invariant, i.e., the only relevant variable is the ratio of the current volume in the queue to its average value. While the latter shows intraday seasonalities and strong variability across stocks and time periods, the dynamics of the rescaled volumes is universal. In terms of rescaled volumes, we found that the drift has a complex two-dimensional structure, which is a sum of a gradient contribution and a rotational contribution, both stable across stocks and time. This drift term is entirely responsible for the dynamical correlations between the ask queue and the bid queue.

  18. Research on elastic resource management for multi-queue under cloud computing environment

    NASA Astrophysics Data System (ADS)

    CHENG, Zhenjing; LI, Haibo; HUANG, Qiulan; Cheng, Yaodong; CHEN, Gang

    2017-10-01

    As a new approach to manage computing resource, virtualization technology is more and more widely applied in the high-energy physics field. A virtual computing cluster based on Openstack was built at IHEP, using HTCondor as the job queue management system. In a traditional static cluster, a fixed number of virtual machines are pre-allocated to the job queue of different experiments. However this method cannot be well adapted to the volatility of computing resource requirements. To solve this problem, an elastic computing resource management system under cloud computing environment has been designed. This system performs unified management of virtual computing nodes on the basis of job queue in HTCondor based on dual resource thresholds as well as the quota service. A two-stage pool is designed to improve the efficiency of resource pool expansion. This paper will present several use cases of the elastic resource management system in IHEPCloud. The practical run shows virtual computing resource dynamically expanded or shrunk while computing requirements change. Additionally, the CPU utilization ratio of computing resource was significantly increased when compared with traditional resource management. The system also has good performance when there are multiple condor schedulers and multiple job queues.

  19. Dynamic properties of chasers in a moving queue based on a delayed chasing model

    NASA Astrophysics Data System (ADS)

    Ning, Guo; Jian-Xun, Ding; Xiang, Ling; Qin, Shi; Reinhart, Kühne

    2016-05-01

    A delayed chasing model is proposed to simulate the chase behavior in the queue, where each member regards the closest one ahead as the target, and the leader is attracted to a target point with slight fluctuation. When the initial distances between neighbors possess an identical low value, the fluctuating target of the leader can cause an amplified disturbance in the queue. After a long period of time, the queue recovers the stable state from the disturbance, forming a straight-line-like pattern again, but distances between neighbors grow. Whether the queue can keep stable or not depends on initial distance, desired velocity, and relaxation time. Furthermore, we carry out convergence analysis to explain the divergence transformation behavior and confirm the convergence conditions, which is in approximate agreement with simulations. Project supported by the National Natural Science Foundation of China (Grant Nos. 71071044, 71001001, 71201041, and 11247291), the Doctoral Program of the Ministry of Education of China (Grant Nos. 20110111120023 and 20120111120022), the Postdoctoral Fund Project of China (Grant No. 2013M530295), the National Basic Research Program of China (Grant No. 2012CB725404), and 1000 Plan for Foreign Talent, China (Grant No. WQ20123400070).

  20. A kinematic wave model in Lagrangian coordinates incorporating capacity drop: Application to homogeneous road stretches and discontinuities

    NASA Astrophysics Data System (ADS)

    Yuan, Kai; Knoop, Victor L.; Hoogendoorn, Serge P.

    2017-01-01

    On freeways, congestion always leads to capacity drop. This means the queue discharge rate is lower than the pre-queue capacity. Our recent research findings indicate that the queue discharge rate increases with the speed in congestion, that is the capacity drop is strongly correlated with the congestion state. Incorporating this varying capacity drop into a kinematic wave model is essential for assessing consequences of control strategies. However, to the best of authors' knowledge, no such a model exists. This paper fills the research gap by presenting a Lagrangian kinematic wave model. "Lagrangian" denotes that the new model is solved in Lagrangian coordinates. The new model can give capacity drops accompanying both of stop-and-go waves (on homogeneous freeway section) and standing queues (at nodes) in a network. The new model can be applied in a network operation. In this Lagrangian kinematic wave model, the queue discharge rate (or the capacity drop) is a function of vehicular speed in traffic jams. Four case studies on links as well as at lane-drop and on-ramp nodes show that the Lagrangian kinematic wave model can give capacity drops well, consistent with empirical observations.

  1. CPAP Tips

    MedlinePlus

    ... starting stop Loading... Watch Queue Queue __count__/__total__ YouTube Premium Loading... Get YouTube without the ads. Working... No thanks 3-months ... use your CPAP device. Category Education License Standard YouTube License Show more Show less Comments are disabled ...

  2. Optimal and Approximately Optimal Control Policies for Queues in Heavy Traffic,

    DTIC Science & Technology

    1987-03-01

    optimal and ’nearly optimal’ control problems for the open queueing networks in heavy traffic of the type dealt with in the fundamental papers of Reiman ...then the covariance is precisely that obtained by Reiman [1] (with a different notation used there). It is evident from (4.4) and the cited...wU’ ’U, d A K . " -50- References [1] M.I. Reiman , "Open queueing networks in heavy traffic", Math. of Operations Research, 9, 1984, p. 441-458. [2] J

  3. Arranging computer architectures to create higher-performance controllers

    NASA Technical Reports Server (NTRS)

    Jacklin, Stephen A.

    1988-01-01

    Techniques for integrating microprocessors, array processors, and other intelligent devices in control systems are reviewed, with an emphasis on the (re)arrangement of components to form distributed or parallel processing systems. Consideration is given to the selection of the host microprocessor, increasing the power and/or memory capacity of the host, multitasking software for the host, array processors to reduce computation time, the allocation of real-time and non-real-time events to different computer subsystems, intelligent devices to share the computational burden for real-time events, and intelligent interfaces to increase communication speeds. The case of a helicopter vibration-suppression and stabilization controller is analyzed as an example, and significant improvements in computation and throughput rates are demonstrated.

  4. Development of traffic control and queue management procedures for oversaturated arterials

    DOT National Transportation Integrated Search

    1997-01-01

    The formulation and solution of a new algorithm for queue management and coordination of traffic signals along oversaturated arterials are presented. Existing traffic-control and signal-coordination algorithms deal only with undersaturated steady-sta...

  5. Report on dynamic speed harmonization and queue warning algorithm design.

    DOT National Transportation Integrated Search

    2014-02-01

    This report provides a detailed description of the algorithms that will be used to generate harmonized recommended speeds and queue warning information in the proposed Intelligent Network Flow Optimization (INFLO) prototype. This document describes t...

  6. Data traffic reduction schemes for Cholesky factorization on asynchronous multiprocessor systems

    NASA Technical Reports Server (NTRS)

    Naik, Vijay K.; Patrick, Merrell L.

    1989-01-01

    Communication requirements of Cholesky factorization of dense and sparse symmetric, positive definite matrices are analyzed. The communication requirement is characterized by the data traffic generated on multiprocessor systems with local and shared memory. Lower bound proofs are given to show that when the load is uniformly distributed the data traffic associated with factoring an n x n dense matrix using n to the alpha power (alpha less than or equal 2) processors is omega(n to the 2 + alpha/2 power). For n x n sparse matrices representing a square root of n x square root of n regular grid graph the data traffic is shown to be omega(n to the 1 + alpha/2 power), alpha less than or equal 1. Partitioning schemes that are variations of block assignment scheme are described and it is shown that the data traffic generated by these schemes are asymptotically optimal. The schemes allow efficient use of up to O(n to the 2nd power) processors in the dense case and up to O(n) processors in the sparse case before the total data traffic reaches the maximum value of O(n to the 3rd power) and O(n to the 3/2 power), respectively. It is shown that the block based partitioning schemes allow a better utilization of the data accessed from shared memory and thus reduce the data traffic than those based on column-wise wrap around assignment schemes.

  7. Estimating the waiting time of multi-priority emergency patients with downstream blocking.

    PubMed

    Lin, Di; Patrick, Jonathan; Labeau, Fabrice

    2014-03-01

    To characterize the coupling effect between patient flow to access the emergency department (ED) and that to access the inpatient unit (IU), we develop a model with two connected queues: one upstream queue for the patient flow to access the ED and one downstream queue for the patient flow to access the IU. Building on this patient flow model, we employ queueing theory to estimate the average waiting time across patients. Using priority specific wait time targets, we further estimate the necessary number of ED and IU resources. Finally, we investigate how an alternative way of accessing ED (Fast Track) impacts the average waiting time of patients as well as the necessary number of ED/IU resources. This model as well as the analysis on patient flow can help the designer or manager of a hospital make decisions on the allocation of ED/IU resources in a hospital.

  8. Paying for Express Checkout: Competition and Price Discrimination in Multi-Server Queuing Systems

    PubMed Central

    Deck, Cary; Kimbrough, Erik O.; Mongrain, Steeve

    2014-01-01

    We model competition between two firms selling identical goods to customers who arrive in the market stochastically. Shoppers choose where to purchase based upon both price and the time cost associated with waiting for service. One seller provides two separate queues, each with its own server, while the other seller has a single queue and server. We explore the market impact of the multi-server seller engaging in waiting cost-based-price discrimination by charging a premium for express checkout. Specifically, we analyze this situation computationally and through the use of controlled laboratory experiments. We find that this form of price discrimination is harmful to sellers and beneficial to consumers. When the two-queue seller offers express checkout for impatient customers, the single queue seller focuses on the patient shoppers thereby driving down prices and profits while increasing consumer surplus. PMID:24667809

  9. Synchronized flow in oversaturated city traffic.

    PubMed

    Kerner, Boris S; Klenov, Sergey L; Hermanns, Gerhard; Hemmerle, Peter; Rehborn, Hubert; Schreckenberg, Michael

    2013-11-01

    Based on numerical simulations with a stochastic three-phase traffic flow model, we reveal that moving queues (moving jams) in oversaturated city traffic dissolve at some distance upstream of the traffic signal while transforming into synchronized flow. It is found that, as in highway traffic [Kerner, Phys. Rev. E 85, 036110 (2012)], such a jam-absorption effect in city traffic is explained by a strong driver's speed adaptation: Time headways (space gaps) between vehicles increase upstream of a moving queue (moving jam), resulting in moving queue dissolution. It turns out that at given traffic signal parameters, the stronger the speed adaptation effect, the shorter the mean distance between the signal location and the road location at which moving queues dissolve fully and oversaturated traffic consists of synchronized flow only. A comparison of the synchronized flow in city traffic found in this Brief Report with synchronized flow in highway traffic is made.

  10. On the optimal use of a slow server in two-stage queueing systems

    NASA Astrophysics Data System (ADS)

    Papachristos, Ioannis; Pandelis, Dimitrios G.

    2017-07-01

    We consider two-stage tandem queueing systems with a dedicated server in each queue and a slower flexible server that can attend both queues. We assume Poisson arrivals and exponential service times, and linear holding costs for jobs present in the system. We study the optimal dynamic assignment of servers to jobs assuming that two servers cannot collaborate to work on the same job and preemptions are not allowed. We formulate the problem as a Markov decision process and derive properties of the optimal allocation for the dedicated (fast) servers. Specifically, we show that the one downstream should not idle, and the same is true for the one upstream when holding costs are larger there. The optimal allocation of the slow server is investigated through extensive numerical experiments that lead to conjectures on the structure of the optimal policy.

  11. Paying for express checkout: competition and price discrimination in multi-server queuing systems.

    PubMed

    Deck, Cary; Kimbrough, Erik O; Mongrain, Steeve

    2014-01-01

    We model competition between two firms selling identical goods to customers who arrive in the market stochastically. Shoppers choose where to purchase based upon both price and the time cost associated with waiting for service. One seller provides two separate queues, each with its own server, while the other seller has a single queue and server. We explore the market impact of the multi-server seller engaging in waiting cost-based-price discrimination by charging a premium for express checkout. Specifically, we analyze this situation computationally and through the use of controlled laboratory experiments. We find that this form of price discrimination is harmful to sellers and beneficial to consumers. When the two-queue seller offers express checkout for impatient customers, the single queue seller focuses on the patient shoppers thereby driving down prices and profits while increasing consumer surplus.

  12. Synchronized flow in oversaturated city traffic

    NASA Astrophysics Data System (ADS)

    Kerner, Boris S.; Klenov, Sergey L.; Hermanns, Gerhard; Hemmerle, Peter; Rehborn, Hubert; Schreckenberg, Michael

    2013-11-01

    Based on numerical simulations with a stochastic three-phase traffic flow model, we reveal that moving queues (moving jams) in oversaturated city traffic dissolve at some distance upstream of the traffic signal while transforming into synchronized flow. It is found that, as in highway traffic [Kerner, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.85.036110 85, 036110 (2012)], such a jam-absorption effect in city traffic is explained by a strong driver's speed adaptation: Time headways (space gaps) between vehicles increase upstream of a moving queue (moving jam), resulting in moving queue dissolution. It turns out that at given traffic signal parameters, the stronger the speed adaptation effect, the shorter the mean distance between the signal location and the road location at which moving queues dissolve fully and oversaturated traffic consists of synchronized flow only. A comparison of the synchronized flow in city traffic found in this Brief Report with synchronized flow in highway traffic is made.

  13. Design and implementation of a medium speed communications interface and protocol for a low cost, refreshed display computer

    NASA Technical Reports Server (NTRS)

    Phyne, J. R.; Nelson, M. D.

    1975-01-01

    The design and implementation of hardware and software systems involved in using a 40,000 bit/second communication line as the connecting link between an IMLAC PDS 1-D display computer and a Univac 1108 computer system were described. The IMLAC consists of two independent processors sharing a common memory. The display processor generates the deflection and beam control currents as it interprets a program contained in the memory; the minicomputer has a general instruction set and is responsible for starting and stopping the display processor and for communicating with the outside world through the keyboard, teletype, light pen, and communication line. The processing time associated with each data byte was minimized by designing the input and output processes as finite state machines which automatically sequence from each state to the next. Several tests of the communication link and the IMLAC software were made using a special low capacity computer grade cable between the IMLAC and the Univac.

  14. An efficient parallel-processing method for transposing large matrices in place.

    PubMed

    Portnoff, M R

    1999-01-01

    We have developed an efficient algorithm for transposing large matrices in place. The algorithm is efficient because data are accessed either sequentially in blocks or randomly within blocks small enough to fit in cache, and because the same indexing calculations are shared among identical procedures operating on independent subsets of the data. This inherent parallelism makes the method well suited for a multiprocessor computing environment. The algorithm is easy to implement because the same two procedures are applied to the data in various groupings to carry out the complete transpose operation. Using only a single processor, we have demonstrated nearly an order of magnitude increase in speed over the previously published algorithm by Gate and Twigg for transposing a large rectangular matrix in place. With multiple processors operating in parallel, the processing speed increases almost linearly with the number of processors. A simplified version of the algorithm for square matrices is presented as well as an extension for matrices large enough to require virtual memory.

  15. Implementing the PM Programming Language using MPI and OpenMP - a New Tool for Programming Geophysical Models on Parallel Systems

    NASA Astrophysics Data System (ADS)

    Bellerby, Tim

    2015-04-01

    PM (Parallel Models) is a new parallel programming language specifically designed for writing environmental and geophysical models. The language is intended to enable implementers to concentrate on the science behind the model rather than the details of running on parallel hardware. At the same time PM leaves the programmer in control - all parallelisation is explicit and the parallel structure of any given program may be deduced directly from the code. This paper describes a PM implementation based on the Message Passing Interface (MPI) and Open Multi-Processing (OpenMP) standards, looking at issues involved with translating the PM parallelisation model to MPI/OpenMP protocols and considering performance in terms of the competing factors of finer-grained parallelisation and increased communication overhead. In order to maximise portability, the implementation stays within the MPI 1.3 standard as much as possible, with MPI-2 MPI-IO file handling the only significant exception. Moreover, it does not assume a thread-safe implementation of MPI. PM adopts a two-tier abstract representation of parallel hardware. A PM processor is a conceptual unit capable of efficiently executing a set of language tasks, with a complete parallel system consisting of an abstract N-dimensional array of such processors. PM processors may map to single cores executing tasks using cooperative multi-tasking, to multiple cores or even to separate processing nodes, efficiently sharing tasks using algorithms such as work stealing. While tasks may move between hardware elements within a PM processor, they may not move between processors without specific programmer intervention. Tasks are assigned to processors using a nested parallelism approach, building on ideas from Reyes et al. (2009). The main program owns all available processors. When the program enters a parallel statement then either processors are divided out among the newly generated tasks (number of new tasks < number of processors) or tasks are divided out among the available processors (number of tasks > number of processors). Nested parallel statements may further subdivide the processor set owned by a given task. Tasks or processors are distributed evenly by default, but uneven distributions are possible under programmer control. It is also possible to explicitly enable child tasks to migrate within the processor set owned by their parent task, reducing load unbalancing at the potential cost of increased inter-processor message traffic. PM incorporates some programming structures from the earlier MIST language presented at a previous EGU General Assembly, while adopting a significantly different underlying parallelisation model and type system. PM code is available at www.pm-lang.org under an unrestrictive MIT license. Reference Ruymán Reyes, Antonio J. Dorta, Francisco Almeida, Francisco de Sande, 2009. Automatic Hybrid MPI+OpenMP Code Generation with llc, Recent Advances in Parallel Virtual Machine and Message Passing Interface, Lecture Notes in Computer Science Volume 5759, 185-195

  16. Improvements in multimedia data buffering using master/slave architecture

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sheikh, S.; Ganesan, R.

    1996-12-31

    Advances in the networking technology and multimedia technology has necessitated a need for multimedia servers to be robust and reliable. Existing solutions have direct limitations such as I/O bottleneck and reliability of data retrieval. The system can store the stream of incoming data if enough buffer space is available or the mass storage is clearing the buffer data faster than queue input. A single buffer queue is not sufficient to handle the large frames. Queue sizes are normally several megabytes in length and thus in turn will introduce a state of overflow. The system should also keep track of themore » rewind, fast forwarding, and pause requests, otherwise queue management will become intricate. In this paper, we present a master/slave (server that is designated to monitor the workflow of the complete system. This server holds every other information of slaves by maintaining a dynamic table. It also controls the workload on each of the systems by redistributing request to others or handles the request by itself) approach which will overcome the limitations of today`s storage and also satisfy tomorrow`s storage needs. This approach will maintain the system reliability and yield faster response by using more storage units in parallel. A network of master/slave can handle many requests and synchronize them at all times. Using dedicated CPU and a common pool of queues we explain how queues can be controlled and buffer overflow can be avoided. We propose a layered approach to the buffering problem and provide a read-ahead solution to ensure continuous storage and retrieval of multimedia data.« less

  17. Pathogen transfer through environment-host contact: an agent-based queueing theoretic framework.

    PubMed

    Chen, Shi; Lenhart, Suzanne; Day, Judy D; Lee, Chihoon; Dulin, Michael; Lanzas, Cristina

    2017-11-02

    Queueing theory studies the properties of waiting queues and has been applied to investigate direct host-to-host transmitted disease dynamics, but its potential in modelling environmentally transmitted pathogens has not been fully explored. In this study, we provide a flexible and customizable queueing theory modelling framework with three major subroutines to study the in-hospital contact processes between environments and hosts and potential nosocomial pathogen transfer, where environments are servers and hosts are customers. Two types of servers with different parameters but the same utilization are investigated. We consider various forms of transfer functions that map contact duration to the amount of pathogen transfer based on existing literature. We propose a case study of simulated in-hospital contact processes and apply stochastic queues to analyse the amount of pathogen transfer under different transfer functions, and assume that pathogen amount decreases during the inter-arrival time. Different host behaviour (feedback and non-feedback) as well as initial pathogen distribution (whether in environment and/or in hosts) are also considered and simulated. We assess pathogen transfer and circulation under these various conditions and highlight the importance of the nonlinear interactions among contact processes, transfer functions and pathogen demography during the contact process. Our modelling framework can be readily extended to more complicated queueing networks to simulate more realistic situations by adjusting parameters such as the number and type of servers and customers, and adding extra subroutines. © The authors 2017. Published by Oxford University Press on behalf of the Institute of Mathematics and its Applications. All rights reserved.

  18. Load sharing in distributed real-time systems with state-change broadcasts

    NASA Technical Reports Server (NTRS)

    Shin, Kang G.; Chang, Yi-Chieh

    1989-01-01

    A decentralized dynamic load-sharing (LS) method based on state-change broadcasts is proposed for a distributed real-time system. Whenever the state of a node changes from underloaded to fully loaded and vice versa, the node broadcasts this change to a set of nodes, called a buddy set, in the system. The performance of the method is evaluated with both analytic modeling and simulation. It is modeled first by an embedded Markov chain for which numerical solutions are derived. The model solutions are then used to calculate the distribution of queue lengths at the nodes and the probability of meeting task deadlines. The analytical results show that buddy sets of 10 nodes outperform those of less than 10 nodes, and the incremental benefit gained from increasing the buddy set size beyond 15 nodes is insignificant. These and other analytical results are verified by simulation. The proposed LS method is shown to meet task deadlines with a very high probability.

  19. AN Integrated Bibliographic Information System: Concept and Application for Resource Sharing in Special Libraries

    DTIC Science & Technology

    1987-05-01

    workload (beyond that of say an equivalent academic or corporate technical libary ) for the Defense Department libraries. Figure 9 illustrates the range...summer. The hardware configuration for the system is as follows: " Digital Equipment Corporation VAX 11/750 central processor with 6 mega- bytes of real

  20. 50 CFR 680.40 - Crab Quota Share (QS), Processor QS (PQS), Individual Fishing Quota (IFQ), and Individual...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... exclude any deadloss, test fishing, fishing conducted under an experimental, exploratory, or scientific..., education, exploratory, or experimental permit, or under the Western Alaska CDQ Program. (iv) Documentation... information is true, correct, and complete to the best of his/her knowledge and belief. If the application is...

  1. 50 CFR 680.40 - Crab Quota Share (QS), Processor QS (PQS), Individual Fishing Quota (IFQ), and Individual...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... exclude any deadloss, test fishing, fishing conducted under an experimental, exploratory, or scientific..., education, exploratory, or experimental permit, or under the Western Alaska CDQ Program. (iv) Documentation... information is true, correct, and complete to the best of his/her knowledge and belief. If the application is...

  2. 50 CFR 680.40 - Crab Quota Share (QS), Processor QS (PQS), Individual Fishing Quota (IFQ), and Individual...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... exclude any deadloss, test fishing, fishing conducted under an experimental, exploratory, or scientific..., education, exploratory, or experimental permit, or under the Western Alaska CDQ Program. (iv) Documentation... information is true, correct, and complete to the best of his/her knowledge and belief. If the application is...

  3. 50 CFR 680.40 - Crab Quota Share (QS), Processor QS (PQS), Individual Fishing Quota (IFQ), and Individual...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... exclude any deadloss, test fishing, fishing conducted under an experimental, exploratory, or scientific..., education, exploratory, or experimental permit, or under the Western Alaska CDQ Program. (iv) Documentation... information is true, correct, and complete to the best of his/her knowledge and belief. If the application is...

  4. Sharing Writing on an Electronic Network.

    ERIC Educational Resources Information Center

    Schwartz, Jeffrey

    A writing exchange project at Bread Loaf School of English at Middlebury College in Vermont, funded by Apple Education Foundation and McDonnell Douglas, examined what happened when high school students use word processors and a modem to write to distant audiences. In the first exchange, students interviewed each other in pairs and wrote short…

  5. Cache write generate for parallel image processing on shared memory architectures.

    PubMed

    Wittenbrink, C M; Somani, A K; Chen, C H

    1996-01-01

    We investigate cache write generate, our cache mode invention. We demonstrate that for parallel image processing applications, the new mode improves main memory bandwidth, CPU efficiency, cache hits, and cache latency. We use register level simulations validated by the UW-Proteus system. Many memory, cache, and processor configurations are evaluated.

  6. Challenging prior evidence for a shared syntactic processor for language and music.

    PubMed

    Perruchet, Pierre; Poulin-Charronnat, Bénédicte

    2013-04-01

    A theoretical landmark in the growing literature comparing language and music is the shared syntactic integration resource hypothesis (SSIRH; e.g., Patel, 2008), which posits that the successful processing of linguistic and musical materials relies, at least partially, on the mastery of a common syntactic processor. Supporting the SSIRH, Slevc, Rosenberg, and Patel (Psychonomic Bulletin & Review 16(2):374-381, 2009) recently reported data showing enhanced syntactic garden path effects when the sentences were paired with syntactically unexpected chords, whereas the musical manipulation had no reliable effect on the processing of semantic violations. The present experiment replicated Slevc et al.'s (2009) procedure, except that syntactic garden paths were replaced with semantic garden paths. We observed the very same interactive pattern of results. These findings suggest that the element underpinning interactions is the garden path configuration, rather than the implication of an alleged syntactic module. We suggest that a different amount of attentional resources is recruited to process each type of linguistic manipulations, hence modulating the resources left available for the processing of music and, consequently, the effects of musical violations.

  7. Modeling Human Supervisory Control in Heterogeneous Unmanned Vehicle Systems

    DTIC Science & Technology

    2009-02-01

    events through a queue, nominally due to another queue having reached its capacity limitation (Balsamo, Persone, & Onvural, 2001; Onvural, 1990; Perros ...Communication and Coordination, Athens, Greece. Perros , H. G. (1984). Queuing Networks with Blocking: A Bibliography. ACM Sigmetrics, Performance Evaluation

  8. A new traffic control design method for large networks with signalized intersections

    NASA Technical Reports Server (NTRS)

    Leininger, G. G.; Colony, D. C.; Seldner, K.

    1979-01-01

    The paper presents a traffic control design technique for application to large traffic networks with signalized intersections. It is shown that the design method adopts a macroscopic viewpoint to establish a new traffic modelling procedure in which vehicle platoons are subdivided into main stream queues and turning queues. Optimization of the signal splits minimizes queue lengths in the steady state condition and improves traffic flow conditions, from the viewpoint of the traveling public. Finally, an application of the design method to a traffic network with thirty-three signalized intersections is used to demonstrate the effectiveness of the proposed technique.

  9. Departure Queue Prediction for Strategic and Tactical Surface Scheduler Integration

    NASA Technical Reports Server (NTRS)

    Zelinski, Shannon; Windhorst, Robert

    2016-01-01

    A departure metering concept to be demonstrated at Charlotte Douglas International Airport (CLT) will integrate strategic and tactical surface scheduling components to enable the respective collaborative decision making and improved efficiency benefits these two methods of scheduling provide. This study analyzes the effect of tactical scheduling on strategic scheduler predictability. Strategic queue predictions and target gate pushback times to achieve a desired queue length are compared between fast time simulations of CLT surface operations with and without tactical scheduling. The use of variable departure rates as a strategic scheduler input was shown to substantially improve queue predictions over static departure rates. With target queue length calibration, the strategic scheduler can be tuned to produce average delays within one minute of the tactical scheduler. However, root mean square differences between strategic and tactical delays were between 12 and 15 minutes due to the different methods the strategic and tactical schedulers use to predict takeoff times and generate gate pushback clearances. This demonstrates how difficult it is for the strategic scheduler to predict tactical scheduler assigned gate delays on an individual flight basis as the tactical scheduler adjusts departure sequence to accommodate arrival interactions. Strategic/tactical scheduler compatibility may be improved by providing more arrival information to the strategic scheduler and stabilizing tactical scheduler changes to runway sequence in response to arrivals.

  10. Supporting shared data structures on distributed memory architectures

    NASA Technical Reports Server (NTRS)

    Koelbel, Charles; Mehrotra, Piyush; Vanrosendale, John

    1990-01-01

    Programming nonshared memory systems is more difficult than programming shared memory systems, since there is no support for shared data structures. Current programming languages for distributed memory architectures force the user to decompose all data structures into separate pieces, with each piece owned by one of the processors in the machine, and with all communication explicitly specified by low-level message-passing primitives. A new programming environment is presented for distributed memory architectures, providing a global name space and allowing direct access to remote parts of data values. The analysis and program transformations required to implement this environment are described, and the efficiency of the resulting code on the NCUBE/7 and IPSC/2 hypercubes are described.

  11. Technical report on prototype intelligent network flow optimization (INFLO) dynamic speed harmonization and queue warning.

    DOT National Transportation Integrated Search

    2015-06-01

    This Technical Report on Prototype Intelligent Network Flow Optimization (INFLO) Dynamic Speed Harmonization and Queue Warning is the final report for the project. It describes the prototyping, acceptance testing and small-scale demonstration of the ...

  12. Research into Queueing Network Theory.

    DTIC Science & Technology

    1977-09-01

    and Zeigler, B. (1975) "Equilibrium properties of arbitrarily interconnected queueing netowrks ," Tech. Report 75-4, Computer and Communication...Associate. The project was extremely fortunate to secure the services of Dr. Wendel. Dr. Wendel was a project member for one month in the summer of

  13. Identifying effects and applications of fixed and variable speed limits.

    DOT National Transportation Integrated Search

    2016-08-01

    In Indiana, distracted driving and unexpected queues have led to an increase in the amount of back-of-queue crashes, particularly on approach to : work zones. This report presents new strategies for the assessment of both transportation safety and tr...

  14. Real-time prediction of queues at signalized intersections to support eco-driving applications.

    DOT National Transportation Integrated Search

    2014-10-01

    The overall objective of this research is to develop models for predicting queue lengths at signalized intersections based on : the data from probe vehicles. The time and space coordinates of the probe vehicles going through signalized intersections ...

  15. A Cellular Neural Networks Based DiffServ Switch for Satellite Communication Systems

    NASA Astrophysics Data System (ADS)

    Tarchi, Daniele; Fantacci, Romano; Gubellini, Roberto; Pecorella, Tommaso

    2003-07-01

    Recent developments of Internet services and advanced compression methods has revived interest on IP based multimedia satellite communication systems. However a main problem arising here is to guarantee specific Quality of Service (QoS) constraints in order to have good performance for each traffic class.Among various QoS approach used in Internet, recently the DiffServ technique has became the most promising so- lution, mainly for its simplicity with respect to different alternatives. Moreover, in satellite communication systems, DiffServ policy computational capabilities are placed at the edge points (end-to-end philosophy); this is very important for a network constituted by one satellite link because it allows to reduce the implementation complexity of the satellite on-board equipments.The satellite switch under consideration makes use of the Multiple Input Queuing approach. Packets arrived at a switch input are stored in a shared buffer but they are logically ordered in individual queues, one for each possible output link. According to the DiffServ policy, within a same logical queue, packets are reordered in individual sub-queues according to the priority. A suitable implementation of the DiffServ policy based on a Cellular Neural Network (CNN) is proposed in the paper in order to achieve QoS requirements.The CNNs are a set of linear and nonlinear circuits connected among them that allow parallel and asynchronous computation. CNNs are a class of neural networks similar to Hopfield Neural Networks (HNN), but more flexible and suitable for solving the output contention problem, inherent of switching systems, for VLSI implementation.In this paper a CNN has been designed in order to maximize a cost functional, related to the on-board switch through- put and QoS constraints. The initial state for each neural cell is obtained looking at the presence of at least one packet from a certain input logical queue to a specific output line. The input value for each neural cell is a function of priority and length of each input logical queue. The versatility of neural network make feasible to take the best decision for the packet to be delivered to each output satellite beam, in order to meet specific QoS constraints. Numerical results for CNN approach highlights that Neural network convergence within a time slot is guaranteed, and an optimal, or at least near-optimal, solution in terms of cost function is achieved.The proposed system is based on the IETF (Internet Engineering Task Force) recommendations; this means that traffic entering the switching fabric could be marked as Expedited Forward (EF) or Assured Forward (AF), otherwise handled as Best Effort (BE). Two Assured Forward classes with different emission priority have been implemented, taking into account time spent inside the logical queue and its length. Expedited Forward traffic is typical of services to be delivered with the maximum priority, as streaming or interactive services. The packets, belonging to services that need a certain level of priority with low packet loss, are marked as Assured Forward. Best Effort traffic is related to e-mail or file transfer, or other that have not particular QoS requirements. The CNN used to solve conflict situations act as an arbiter for all the output links. Differently from other Multiple Input Queuing approach, where one arbiter for each output line is present, in proposed approach there exist only one arbiter that make the best decision. The selected rule has been defined in order to give priority to packets, according to opportunely defined functionals characteristic of each traffic class, under the constraint that no more than one packet can be delivered to the same output line. The functionals depend on queue length and time spent inside the queue by front packet.The performance of the proposed DiffServ switch has been derived in terms of delay and jitter; buffer occupancy has been analyzed for different configuration, such as a unique common buffer, one buffer for each input line, one buffer for each input line and each priority class.The obtained results highlight an high flexibility of satellite switch with CNN, taking into account that functional used to calculate priority of each queue could be easily changed, without any complexity gain nor change in CNN structure, in order to consider different traffic characteristic. Numerical results show that proposed algorithm outperform the switches based on Multiple Input Queuing, that use strictly priority methods, in terms of delay and jitter. Different buffer size have been also considered in order to analyze packet loss for CNN switch algorithm, comparing different configuration described above.The good behavior of the proposed DiffServ switch has been verified in the case of traffic with pareto distribution for packet length and a geometrical distribution for packet interarrival time, highlighting good performance in terms of delay and jitter. Numerical results also demonstrate the stability of this method for heavy load traffic; in particular maximum permitted load is higher for higher priority classes.

  16. A communication-avoiding, hybrid-parallel, rank-revealing orthogonalization method.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hoemmen, Mark

    2010-11-01

    Orthogonalization consumes much of the run time of many iterative methods for solving sparse linear systems and eigenvalue problems. Commonly used algorithms, such as variants of Gram-Schmidt or Householder QR, have performance dominated by communication. Here, 'communication' includes both data movement between the CPU and memory, and messages between processors in parallel. Our Tall Skinny QR (TSQR) family of algorithms requires asymptotically fewer messages between processors and data movement between CPU and memory than typical orthogonalization methods, yet achieves the same accuracy as Householder QR factorization. Furthermore, in block orthogonalizations, TSQR is faster and more accurate than existing approaches formore » orthogonalizing the vectors within each block ('normalization'). TSQR's rank-revealing capability also makes it useful for detecting deflation in block iterative methods, for which existing approaches sacrifice performance, accuracy, or both. We have implemented a version of TSQR that exploits both distributed-memory and shared-memory parallelism, and supports real and complex arithmetic. Our implementation is optimized for the case of orthogonalizing a small number (5-20) of very long vectors. The shared-memory parallel component uses Intel's Threading Building Blocks, though its modular design supports other shared-memory programming models as well, including computation on the GPU. Our implementation achieves speedups of 2 times or more over competing orthogonalizations. It is available now in the development branch of the Trilinos software package, and will be included in the 10.8 release.« less

  17. Contention Modeling for Multithreaded Distributed Shared Memory Machines: The Cray XMT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Secchi, Simone; Tumeo, Antonino; Villa, Oreste

    Distributed Shared Memory (DSM) machines are a wide class of multi-processor computing systems where a large virtually-shared address space is mapped on a network of physically distributed memories. High memory latency and network contention are two of the main factors that limit performance scaling of such architectures. Modern high-performance computing DSM systems have evolved toward exploitation of massive hardware multi-threading and fine-grained memory hashing to tolerate irregular latencies, avoid network hot-spots and enable high scaling. In order to model the performance of such large-scale machines, parallel simulation has been proved to be a promising approach to achieve good accuracy inmore » reasonable times. One of the most critical factors in solving the simulation speed-accuracy trade-off is network modeling. The Cray XMT is a massively multi-threaded supercomputing architecture that belongs to the DSM class, since it implements a globally-shared address space abstraction on top of a physically distributed memory substrate. In this paper, we discuss the development of a contention-aware network model intended to be integrated in a full-system XMT simulator. We start by measuring the effects of network contention in a 128-processor XMT machine and then investigate the trade-off that exists between simulation accuracy and speed, by comparing three network models which operate at different levels of accuracy. The comparison and model validation is performed by executing a string-matching algorithm on the full-system simulator and on the XMT, using three datasets that generate noticeably different contention patterns.« less

  18. A parallel algorithm for multi-level logic synthesis using the transduction method. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Lim, Chieng-Fai

    1991-01-01

    The Transduction Method has been shown to be a powerful tool in the optimization of multilevel networks. Many tools such as the SYLON synthesis system (X90), (CM89), (LM90) have been developed based on this method. A parallel implementation is presented of SYLON-XTRANS (XM89) on an eight processor Encore Multimax shared memory multiprocessor. It minimizes multilevel networks consisting of simple gates through parallel pruning, gate substitution, gate merging, generalized gate substitution, and gate input reduction. This implementation, called Parallel TRANSduction (PTRANS), also uses partitioning to break large circuits up and performs inter- and intra-partition dynamic load balancing. With this, good speedups and high processor efficiencies are achievable without sacrificing the resulting circuit quality.

  19. A Tutorial on Parallel and Concurrent Programming in Haskell

    NASA Astrophysics Data System (ADS)

    Peyton Jones, Simon; Singh, Satnam

    This practical tutorial introduces the features available in Haskell for writing parallel and concurrent programs. We first describe how to write semi-explicit parallel programs by using annotations to express opportunities for parallelism and to help control the granularity of parallelism for effective execution on modern operating systems and processors. We then describe the mechanisms provided by Haskell for writing explicitly parallel programs with a focus on the use of software transactional memory to help share information between threads. Finally, we show how nested data parallelism can be used to write deterministically parallel programs which allows programmers to use rich data types in data parallel programs which are automatically transformed into flat data parallel versions for efficient execution on multi-core processors.

  20. 3D environment modeling and location tracking using off-the-shelf components

    NASA Astrophysics Data System (ADS)

    Luke, Robert H.

    2016-05-01

    The remarkable popularity of smartphones over the past decade has led to a technological race for dominance in market share. This has resulted in a flood of new processors and sensors that are inexpensive, low power and high performance. These sensors include accelerometers, gyroscope, barometers and most importantly cameras. This sensor suite, coupled with multicore processors, allows a new community of researchers to build small, high performance platforms for low cost. This paper describes a system using off-the-shelf components to perform position tracking as well as environment modeling. The system relies on tracking using stereo vision and inertial navigation to determine movement of the system as well as create a model of the environment sensed by the system.

  1. Teleoperated position control of a PUMA robot

    NASA Technical Reports Server (NTRS)

    Austin, Edmund; Fong, Chung P.

    1987-01-01

    A laboratory distributed computer control teleoperator system is developed to support NASA's future space telerobotic operation. This teleoperator system uses a universal force-reflecting hand controller in the local iste as the operator's input device. In the remote site, a PUMA controller recieves the Cartesian position commands and implements PID control laws to position the PUMA robot. The local site uses two microprocessors while the remote site uses three. The processors communicate with each other through shared memory. The PUMA robot controller was interfaced through custom made electronics to bypass VAL. The development status of this teleoperator system is reported. The execution time of each processor is analyzed, and the overall system throughput rate is reported. Methods to improve the efficiency and performance are discussed.

  2. Impacts assessment of dynamic speed harmonization with queue warning : task 3, impacts assessment report.

    DOT National Transportation Integrated Search

    2015-06-01

    This report assesses the impacts of a prototype of Dynamic Speed Harmonization (SPD-HARM) with Queue Warning (Q-WARN), which are two component applications of the Intelligent Network Flow Optimization (INFLO) bundle. The assessment is based on an ext...

  3. A queueing theory description of fat-tailed price returns in imperfect financial markets

    NASA Astrophysics Data System (ADS)

    Lamba, H.

    2010-09-01

    In a financial market, for agents with long investment horizons or at times of severe market stress, it is often changes in the asset price that act as the trigger for transactions or shifts in investment position. This suggests the use of price thresholds to simulate agent behavior over much longer timescales than are currently used in models of order-books. We show that many phenomena, routinely ignored in efficient market theory, can be systematically introduced into an otherwise efficient market, resulting in models that robustly replicate the most important stylized facts. We then demonstrate a close link between such threshold models and queueing theory, with large price changes corresponding to the busy periods of a single-server queue. The distribution of the busy periods is known to have excess kurtosis and non-exponential decay under various assumptions on the queue parameters. Such an approach may prove useful in the development of mathematical models for rapid deleveraging and panics in financial markets, and the stress-testing of financial institutions.

  4. Exclusive queueing model including the choice of service windows

    NASA Astrophysics Data System (ADS)

    Tanaka, Masahiro; Yanagisawa, Daichi; Nishinari, Katsuhiro

    2018-01-01

    In a queueing system involving multiple service windows, choice behavior is a significant concern. This paper incorporates the choice of service windows into a queueing model with a floor represented by discrete cells. We contrived a logit-based choice algorithm for agents considering the numbers of agents and the distances to all service windows. Simulations were conducted with various parameters of agent choice preference for these two elements and for different floor configurations, including the floor length and the number of service windows. We investigated the model from the viewpoint of transit times and entrance block rates. The influences of the parameters on these factors were surveyed in detail and we determined that there are optimum floor lengths that minimize the transit times. In addition, we observed that the transit times were determined almost entirely by the entrance block rates. The results of the presented model are relevant to understanding queueing systems including the choice of service windows and can be employed to optimize facility design and floor management.

  5. An energy-efficient MAC protocol using dynamic queue management for delay-tolerant mobile sensor networks.

    PubMed

    Li, Jie; Li, Qiyue; Qu, Yugui; Zhao, Baohua

    2011-01-01

    Conventional MAC protocols for wireless sensor network perform poorly when faced with a delay-tolerant mobile network environment. Characterized by a highly dynamic and sparse topology, poor network connectivity as well as data delay-tolerance, delay-tolerant mobile sensor networks exacerbate the severe power constraints and memory limitations of nodes. This paper proposes an energy-efficient MAC protocol using dynamic queue management (EQ-MAC) for power saving and data queue management. Via data transfers initiated by the target sink and the use of a dynamic queue management strategy based on priority, EQ-MAC effectively avoids untargeted transfers, increases the chance of successful data transmission, and makes useful data reach the target terminal in a timely manner. Experimental results show that EQ-MAC has high energy efficiency in comparison with a conventional MAC protocol. It also achieves a 46% decrease in packet drop probability, 79% increase in system throughput, and 25% decrease in mean packet delay.

  6. An Energy-Efficient MAC Protocol Using Dynamic Queue Management for Delay-Tolerant Mobile Sensor Networks

    PubMed Central

    Li, Jie; Li, Qiyue; Qu, Yugui; Zhao, Baohua

    2011-01-01

    Conventional MAC protocols for wireless sensor network perform poorly when faced with a delay-tolerant mobile network environment. Characterized by a highly dynamic and sparse topology, poor network connectivity as well as data delay-tolerance, delay-tolerant mobile sensor networks exacerbate the severe power constraints and memory limitations of nodes. This paper proposes an energy-efficient MAC protocol using dynamic queue management (EQ-MAC) for power saving and data queue management. Via data transfers initiated by the target sink and the use of a dynamic queue management strategy based on priority, EQ-MAC effectively avoids untargeted transfers, increases the chance of successful data transmission, and makes useful data reach the target terminal in a timely manner. Experimental results show that EQ-MAC has high energy efficiency in comparison with a conventional MAC protocol. It also achieves a 46% decrease in packet drop probability, 79% increase in system throughput, and 25% decrease in mean packet delay. PMID:22319385

  7. Reducing queues: demand and capacity variations.

    PubMed

    Eriksson, Henrik; Bergbrant, Ing-Marie; Berrum, Ingela; Mörck, Boel

    2011-01-01

    The aim of this paper is to investigate how waiting lists or queues could be reduced without adding more resources; and to describe what factors sustain reduced waiting-times. Cases were selected according to successful and sustained queue reduction. The approach in this study is action research. Accessibility improved as out-patient waiting lists for two clinics were reduced. The main success was working towards matching demand and capacity. It has been possible to sustain the improvements. Results should be viewed cautiously. Transferring and generalizing outcomes from this study is for readers to consider. However, accessible healthcare may be possible by paying more attention to existing solutions. The study indicates that queue reduction activities should include acquiring knowledge about theories and methods to improve accessibility, finding ways to monitor varying demand and capacity, and to improve patient processing by reducing variations. Accessibility is considered an important dimension when measuring service quality. However, there are few articles on how clinic staff sustain reduces waiting lists. This paper contributes accessible knowledge to the field.

  8. Rationale choosing interval of a piecewise-constant approximation of input rate of non-stationary queue system

    NASA Astrophysics Data System (ADS)

    Korelin, Ivan A.; Porshnev, Sergey V.

    2018-01-01

    The paper demonstrates the possibility of calculating the characteristics of the flow of visitors to objects carrying out mass events passing through checkpoints. The mathematical model is based on the non-stationary queuing system (NQS) where dependence of requests input rate from time is described by the function. This function was chosen in such way that its properties were similar to the real dependencies of speed of visitors arrival on football matches to the stadium. A piecewise-constant approximation of the function is used when statistical modeling of NQS performing. Authors calculated the dependencies of the queue length and waiting time for visitors to service (time in queue) on time for different laws. Time required to service the entire queue and the number of visitors entering the stadium at the beginning of the match were calculated too. We found the dependence for macroscopic quantitative characteristics of NQS from the number of averaging sections of the input rate.

  9. Queue and stack sorting algorithm optimization and performance analysis

    NASA Astrophysics Data System (ADS)

    Qian, Mingzhu; Wang, Xiaobao

    2018-04-01

    Sorting algorithm is one of the basic operation of a variety of software development, in data structures course specializes in all kinds of sort algorithm. The performance of the sorting algorithm is directly related to the efficiency of the software. A lot of excellent scientific research queue is constantly optimizing algorithm, algorithm efficiency better as far as possible, the author here further research queue combined with stacks of sorting algorithms, the algorithm is mainly used for alternating operation queue and stack storage properties, Thus avoiding the need for a large number of exchange or mobile operations in the traditional sort. Before the existing basis to continue research, improvement and optimization, the focus on the optimization of the time complexity of the proposed optimization and improvement, The experimental results show that the improved effectively, at the same time and the time complexity and space complexity of the algorithm, the stability study corresponding research. The improvement and optimization algorithm, improves the practicability.

  10. Improving queuing service at McDonald's

    NASA Astrophysics Data System (ADS)

    Koh, Hock Lye; Teh, Su Yean; Wong, Chin Keat; Lim, Hooi Kie; Migin, Melissa W.

    2014-07-01

    Fast food restaurants are popular among price-sensitive youths and working adults who value the conducive environment and convenient services. McDonald's chains of restaurants promote their sales during lunch hours by offering package meals which are perceived to be inexpensive. These promotional lunch meals attract good response, resulting in occasional long queues and inconvenient waiting times. A study is conducted to monitor the distribution of waiting time, queue length, customer arrival and departure patterns at a McDonald's restaurant located in Kuala Lumpur. A customer survey is conducted to gauge customers' satisfaction regarding waiting time and queue length. An android app named Que is developed to perform onsite queuing analysis and report key performance indices. The queuing theory in Que is based upon the concept of Poisson distribution. In this paper, Que is utilized to perform queuing analysis at this McDonald's restaurant with the aim of improving customer service, with particular reference to reducing queuing time and shortening queue length. Some results will be presented.

  11. Characteristics of the Unexpected Message Queue of MPI applications

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Keller, Rainer; Graham, Richard L

    2010-01-01

    High Performance Computing systems are used on a regular basis to run a myriad of application codes, yet a surprising dearth of information exists with respect to communications characteristics. Even less information is available on the low-level communication libraries, such as the length of MPI Unexpected Message Queues (UMQs) and the length of time such messages spend in these queues. Such information is vital to developing appropriate strategies for handling such data at the library and system level. In this paper we present data on the communication characteristics of three applications GTC, LSMS, and S3D. We present data on themore » size of their UMQ, the time spend searching the UMQ and the length of time such messages spend in these queues. We find that for the particular inputs used, these applications have widely varying characteristics with regard to UMQ length and show patterns for specific applications which persist over various scales.« less

  12. Application of queuing theory to patient satisfaction at a tertiary hospital in Nigeria

    PubMed Central

    Ameh, Nkeiruka; Sabo, B.; Oyefabi, M. O.

    2013-01-01

    Background: Queuing theory is the mathematical approach to the analysis of waiting lines in any setting where arrival rate of subjects is faster than the system can handle. It is applicable to healthcare settings where the systems have excess capacity to accommodate random variations. Materials and Methods: A cross-sectional descriptive survey was done. Questionnaires were administered to patients who attended the general outpatient department. Observations were also made on the queuing model and the service discipline at the clinic. Questions were meant to obtain demographic characteristics and the time spent on the queue by patients before being seen by a doctor, time spent with the doctor, their views about the time spent on the queue and useful suggestions on how to reduce the time spent on the queue. A total of 210 patients were surveyed. Results: Majority of the patients (164, 78.1%) spent 2 h or less on the queue before being seen by a doctor and less than 1 h to see the doctor. Majority of the patients (144, 68.5%) were satisfied with the time they spent on the queue before being seen by a doctor. Useful suggestions proffered by the patients to decrease the time spent on the queue before seeing a doctor at the clinic included: that more doctors be employed (46, 21.9%), that doctors should come to work on time (25, 11.9%), that first-come-first served be observed strictly (32, 15.2%) and others suggested that the records staff should desist from collecting bribes from patients in order to place their cards before others. The queuing method employed at the clinic is the multiple single channel type and the service discipline is priority service. The patients who spent less time on the queue (<1 h) before seeing the doctor were more satisfied than those who spent more time (P < 0.05). Conclusion: The study has revealed that majority of the patients were satisfied with the practice at the general outpatient department. However, there is a need to employ measures to respond to the suggestions given by the patients who are the beneficiaries of the hospital services. PMID:23661902

  13. 75 FR 13024 - Pacific Halibut Fisheries; Catch Sharing Plan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-18

    ... system for guided charter vessels (75 FR 554) was also established January 5, 2010, for Areas 2C and 3A... resulting catch of which is sold or bartered; or is intended to be sold or bartered, other than (i) sport... fish processor; (t) ``VMS transmitter'' means a NMFS-approved vessel monitoring system transmitter that...

  14. Design, Implementation, and Evaluation of a Virtual Shared Memory System in a Multi-Transputer Network.

    DTIC Science & Technology

    1987-12-01

    Synchronization and Data Passing Mechanism ........ 50 4. System Shut Down .................................................................. 51 5...high performance, fault tolerance, and extensibility. These features are attained by synchronizing and coordinating the dis- tributed multicomputer... synchronizing all processors in the network. In a multitransputer network, processes that communicate with each other do so synchronously . This makes

  15. 77 FR 44216 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-27

    ... of a zero (0) percent fee for cost recovery under the Bering Sea and Aleutian Islands Crab... Program includes a cost recovery provision to collect fees to recover the actual costs directly related to... processing sectors to each pay half the cost recovery fees. Catcher/processor quota share holders are...

  16. High Performance Active Database Management on a Shared-Nothing Parallel Processor

    DTIC Science & Technology

    1998-05-01

    either stored or virtual. A stored node is like a materialized view. It actually contains the specified tuples. A virtual node is like a real view...90292-6695 DL-5 COLUMBIA UNIV/DEPT COMPUTER SCIENCi ATTN: OR GAIL £. KAISER 450 COMPUTER SCIENCE 3LDG 500 WEST 12ÖTH STRSET NEW YORK NY 10027

  17. Gear Up Your Research Guides with the Emerging OPML Codes

    ERIC Educational Resources Information Center

    Wilcox, Kimberley

    2006-01-01

    Outline Processor Markup Language (OPML) is an emerging format that allows for the creation of customized research packages to push to patrons. It is a way to gather collections of Web resources (links, RSS feeds, multimedia files), organize them as outlines, and publish them in a format that others can share and even subscribe to. In this…

  18. Debugging Fortran on a shared memory machine

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Allen, T.R.; Padua, D.A.

    1987-01-01

    Debugging on a parallel processor is more difficult than debugging on a serial machine because errors in a parallel program may introduce nondeterminism. The approach to parallel debugging presented here attempts to reduce the problem of debugging on a parallel machine to that of debugging on a serial machine by automatically detecting nondeterminism. 20 refs., 6 figs.

  19. Sample path analysis of contribution and reward in cooperative groups.

    PubMed

    Toyoizumi, Hiroshi

    2009-02-07

    Explaining cooperative behavior is one of the major challenges in both biology and human society. The individual reward in cooperative group depends on how we share the rewards in the group. Thus, the group size dynamics in a cooperative group and reward-allocation rule seem essential to evaluate the emergence of cooperative groups. We apply a sample path-based analysis called an extension of Little's formula to general cooperative group. We show that the expected reward is insensitive to the specific reward-allocation rule and probabilistic structure of group dynamics, and the simple productivity condition guarantees the expected reward to be larger than the average contribution. As an example, we take social queues to see the insensitivity result in detail.

  20. Autonomous Infrastructure for Observatory Operations

    NASA Astrophysics Data System (ADS)

    Seaman, R.

    This is an era of rapid change from ancient human-mediated modes of astronomical practice to a vision of ever larger time domain surveys, ever bigger "big data", to increasing numbers of robotic telescopes and astronomical automation on every mountaintop. Over the past decades, facets of a new autonomous astronomical toolkit have been prototyped and deployed in support of numerous space missions. Remote and queue observing modes have gained significant market share on the ground. Archives and data-mining are becoming ubiquitous; astroinformatic techniques and virtual observatory standards and protocols are areas of active development. Astronomers and engineers, planetary and solar scientists, and researchers from communities as diverse as particle physics and exobiology are collaborating on a vast range of "multi-messenger" science. What then is missing?

  1. Multi-Resource Fair Queueing for Packet Processing

    DTIC Science & Technology

    2012-06-19

    Huawei , Intel, MarkLogic, Microsoft, NetApp, Oracle, Quanta, Splunk, VMware and by DARPA (contract #FA8650-11-C-7136). Multi-Resource Fair Queueing for...Google PhD Fellowship, gifts from Amazon Web Services, Google, SAP, Blue Goji, Cisco, Cloud- era, Ericsson, General Electric, Hewlett Packard, Huawei

  2. 32 CFR 299.5 - Procedures.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... PROGRAM NATIONAL SECURITY AGENCY/CENTRAL SECURITY SERVICE (NSA/CSS) FREEDOM OF INFORMATION ACT PROGRAM.../CSS by other government agencies shall be placed in the processing queue according to the date the... placed in the queue according to the date of the requester's letter. (d) The FOIA office shall maintain...

  3. Specification and Verification of Communication Protocols in AFFIRM Using State Transition Models.

    DTIC Science & Technology

    1981-03-01

    NewQueueOfftcket; theorem Pendnglnvariant, Remove(Pending(s)) = NewQueueOfPacket; Since the implementation is in keeping with the specification, its salp ...another communication line. The communication lines are unreliable; messages traveling in either direction can be lost, reordered, corrupted, or

  4. A Mixed Integer Linear Program for Airport Departure Scheduling

    NASA Technical Reports Server (NTRS)

    Gupta, Gautam; Jung, Yoon Chul

    2009-01-01

    Aircraft departing from an airport are subject to numerous constraints while scheduling departure times. These constraints include wake-separation constraints for successive departures, miles-in-trail separation for aircraft bound for the same departure fixes, and time-window or prioritization constraints for individual flights. Besides these, emissions as well as increased fuel consumption due to inefficient scheduling need to be included. Addressing all the above constraints in a single framework while allowing for resequencing of the aircraft using runway queues is critical to the implementation of the Next Generation Air Transport System (NextGen) concepts. Prior work on airport departure scheduling has addressed some of the above. However, existing methods use pre-determined runway queues, and schedule aircraft from these departure queues. The source of such pre-determined queues is not explicit, and could potentially be a subjective controller input. Determining runway queues and scheduling within the same framework would potentially result in better scheduling. This paper presents a mixed integer linear program (MILP) for the departure-scheduling problem. The program takes as input the incoming sequence of aircraft for departure from a runway, along with their earliest departure times and an optional prioritization scheme based on time-window of departure for each aircraft. The program then assigns these aircraft to the available departure queues and schedules departure times, explicitly considering wake separation and departure fix restrictions to minimize total delay for all aircraft. The approach is generalized and can be used in a variety of situations, and allows for aircraft prioritization based on operational as well as environmental considerations. We present the MILP in the paper, along with benefits over the first-come-first-serve (FCFS) scheme for numerous randomized problems based on real-world settings. The MILP results in substantially reduced delays as compared to FCFS, and the magnitude of the savings depends on the queue and departure fix structure. The MILP assumes deterministic aircraft arrival times at the runway queues. However, due to taxi time uncertainty, aircraft might arrive either earlier or later than these deterministic times. Thus, to incorporate this uncertainty, we present a method for using the MILP with "overlap discounted rolling planning horizon". The approach is based on valuing near-term decision results more than future ones. We develop a model of taxitime uncertainty based on real-world data, and then compare the baseline FCFS delays with delays using the above MILP in a simple rolling-horizon method and in the overlap discounted scheme.

  5. A lock-free priority queue design based on multi-dimensional linked lists

    DOE PAGES

    Dechev, Damian; Zhang, Deli

    2015-04-03

    The throughput of concurrent priority queues is pivotal to multiprocessor applications such as discrete event simulation, best-first search and task scheduling. Existing lock-free priority queues are mostly based on skiplists, which probabilistically create shortcuts in an ordered list for fast insertion of elements. The use of skiplists eliminates the need of global rebalancing in balanced search trees and ensures logarithmic sequential search time on average, but the worst-case performance is linear with respect to the input size. In this paper, we propose a quiescently consistent lock-free priority queue based on a multi-dimensional list that guarantees worst-case search time of O(logN)more » for key universe of size N. The novel multi-dimensional list (MDList) is composed of nodes that contain multiple links to child nodes arranged by their dimensionality. The insertion operation works by first injectively mapping the scalar key to a high-dimensional vector, then uniquely locating the target position by using the vector as coordinates. Nodes in MDList are ordered by their coordinate prefixes and the ordering property of the data structure is readily maintained during insertion without rebalancing nor randomization. Furthermore, in our experimental evaluation using a micro-benchmark, our priority queue achieves an average of 50% speedup over the state of the art approaches under high concurrency.« less

  6. Moving toward queue operations at the Large Binocular Telescope Observatory

    NASA Astrophysics Data System (ADS)

    Edwards, Michelle L.; Summers, Doug; Astier, Joseph; Suarez Sola, Igor; Veillet, Christian; Power, Jennifer; Cardwell, Andrew; Walsh, Shane

    2016-07-01

    The Large Binocular Telescope Observatory (LBTO), a joint scientific venture between the Instituto Nazionale di Astrofisica (INAF), LBT Beteiligungsgesellschaft (LBTB), University of Arizona, Ohio State University (OSU), and the Research Corporation, is one of the newest additions to the world's collection of large optical/infrared ground-based telescopes. With its unique, twin 8.4m mirror design providing a 22.8 meter interferometric baseline and the collecting area of an 11.8m telescope, LBT has a window of opportunity to exploit its singular status as the "first" of the next generation of Extremely Large Telescopes (ELTs). Prompted by urgency to maximize scientific output during this favorable interval, LBTO recently re-evaluated its operations model and developed a new strategy that augments classical observing with queue. Aided by trained observatory staff, queue mode will allow for flexible, multi-instrument observing responsive to site conditions. Our plan is to implement a staged rollout that will provide many of the benefits of queue observing sooner rather than later - with more bells and whistles coming in future stages. In this paper, we outline LBTO's new scientific model, focusing specifically on our "lean" resourcing and development, reuse and adaptation of existing software, challenges presented from our one-of-a-kind binocular operations, and lessons learned. We also outline further stages of development and our ultimate goals for queue.

  7. A lock-free priority queue design based on multi-dimensional linked lists

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dechev, Damian; Zhang, Deli

    The throughput of concurrent priority queues is pivotal to multiprocessor applications such as discrete event simulation, best-first search and task scheduling. Existing lock-free priority queues are mostly based on skiplists, which probabilistically create shortcuts in an ordered list for fast insertion of elements. The use of skiplists eliminates the need of global rebalancing in balanced search trees and ensures logarithmic sequential search time on average, but the worst-case performance is linear with respect to the input size. In this paper, we propose a quiescently consistent lock-free priority queue based on a multi-dimensional list that guarantees worst-case search time of O(logN)more » for key universe of size N. The novel multi-dimensional list (MDList) is composed of nodes that contain multiple links to child nodes arranged by their dimensionality. The insertion operation works by first injectively mapping the scalar key to a high-dimensional vector, then uniquely locating the target position by using the vector as coordinates. Nodes in MDList are ordered by their coordinate prefixes and the ordering property of the data structure is readily maintained during insertion without rebalancing nor randomization. Furthermore, in our experimental evaluation using a micro-benchmark, our priority queue achieves an average of 50% speedup over the state of the art approaches under high concurrency.« less

  8. System and method for implementing periodic early discard in on-chip buffer memories of network elements

    DOEpatents

    Francini, Andrea

    2013-05-14

    An advance is made over the prior art in accordance with the principles of the present invention that is directed to a new approach for a system and method for a buffer management scheme called Periodic Early Discard (PED). The invention builds on the observation that, in presence of TCP traffic, the length of a queue can be stabilized by selection of an appropriate frequency for packet dropping. For any combination of number of TCP connections and distribution of the respective RTT values, there exists an ideal packet drop frequency that prevents the queue from over-flowing or under-flowing. While the value of the ideal packet drop frequency may quickly change over time and is sensitive to the series of TCP connections affected by past packet losses, and most of all is impossible to compute inline, it is possible to approximate it with a margin of error that allows keeping the queue occupancy within a pre-defined range for extended periods of time. The PED scheme aims at tracking the (unknown) ideal packet drop frequency, adjusting the approximated value based on the evolution of the queue occupancy, with corrections of the approximated packet drop frequency that occur at a timescale that is comparable to the aggregate time constant of the set of TCP connections that traverse the queue.

  9. Impacts Assessment of Dynamic Speed Harmonization with Queue Warning : Task 3, Impacts Assessment Report. [supporting datasets

    DOT National Transportation Integrated Search

    2015-05-31

    The datasets in the .pdf and .zip attached to this record are in support of Intelligent Transportation Systems Joint Program Office (ITS JPO) report FHWA-JPO-15-222, "Impacts Assessment of Dynamic Speed Harmonization with Queue Warning : Task 3, Impa...

  10. Routing in Networks with Random Topologies

    NASA Technical Reports Server (NTRS)

    Bambos, Nicholas

    1997-01-01

    We examine the problems of routing and server assignment in networks with random connectivities. In such a network the basic topology is fixed, but during each time slot and for each of tis input queues, each server (node) is either connected to or disconnected from each of its queues with some probability.

  11. G-cueing microcontroller (a microprocessor application in simulators)

    NASA Technical Reports Server (NTRS)

    Horattas, C. G.

    1980-01-01

    A g cueing microcontroller is described which consists of a tandem pair of microprocessors, dedicated to the task of simulating pilot sensed cues caused by gravity effects. This task includes execution of a g cueing model which drives actuators that alter the configuration of the pilot's seat. The g cueing microcontroller receives acceleration commands from the aerodynamics model in the main computer and creates the stimuli that produce physical acceleration effects of the aircraft seat on the pilots anatomy. One of the two microprocessors is a fixed instruction processor that performs all control and interface functions. The other, a specially designed bipolar bit slice microprocessor, is a microprogrammable processor dedicated to all arithmetic operations. The two processors communicate with each other by a shared memory. The g cueing microcontroller contains its own dedicated I/O conversion modules for interface with the seat actuators and controls, and a DMA controller for interfacing with the simulation computer. Any application which can be microcoded within the available memory, the available real time and the available I/O channels, could be implemented in the same controller.

  12. 77 FR 38013 - Fisheries of the Exclusive Economic Zone Off Alaska; Groundfish of the Gulf of Alaska; Amendment...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-26

    ... participants in the entry level trawl fishery may qualify for quota share (QS) under the Central Gulf of Alaska... landings to an entry level processor in 2007, 2008, or 2009. This clarification is administrative in nature and does not change the distribution of rockfish QS to entry level trawl participants. DATES...

  13. 76 FR 35781 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-20

    ... operational costs. NMFS also issued processor quota share (PQS) under the Program. Each year, PQS yields an... requirements. The RIR/FRFA prepared for this action describes the costs and benefits of Amendment 37 (see... person or company that holds in excess of 20 percent of the West-designated WAG QS; (2) any person or...

  14. Peregrine System Configuration | High-Performance Computing | NREL

    Science.gov Websites

    nodes and storage are connected by a high speed InfiniBand network. Compute nodes are diskless with an directories are mounted on all nodes, along with a file system dedicated to shared projects. A brief processors with 64 GB of memory. All nodes are connected to the high speed Infiniband network and and a

  15. Why K-12 IT Managers and Administrators Are Embracing the Intel-Based Mac

    ERIC Educational Resources Information Center

    Technology & Learning, 2007

    2007-01-01

    Over the past year, Apple has dramatically increased its share of the school computer marketplace--especially in the category of notebook computers. A recent study conducted by Grunwald Associates and Rockman et al. reports that one of the major reasons for this growth is Apple's introduction of the Intel processor to the entire line of Mac…

  16. Importance of balanced architectures in the design of high-performance imaging systems

    NASA Astrophysics Data System (ADS)

    Sgro, Joseph A.; Stanton, Paul C.

    1999-03-01

    Imaging systems employed in demanding military and industrial applications, such as automatic target recognition and computer vision, typically require real-time high-performance computing resources. While high- performances computing systems have traditionally relied on proprietary architectures and custom components, recent advances in high performance general-purpose microprocessor technology have produced an abundance of low cost components suitable for use in high-performance computing systems. A common pitfall in the design of high performance imaging system, particularly systems employing scalable multiprocessor architectures, is the failure to balance computational and memory bandwidth. The performance of standard cluster designs, for example, in which several processors share a common memory bus, is typically constrained by memory bandwidth. The symptom characteristic of this problem is failure to the performance of the system to scale as more processors are added. The problem becomes exacerbated if I/O and memory functions share the same bus. The recent introduction of microprocessors with large internal caches and high performance external memory interfaces makes it practical to design high performance imaging system with balanced computational and memory bandwidth. Real word examples of such designs will be presented, along with a discussion of adapting algorithm design to best utilize available memory bandwidth.

  17. Job Queues, Certification Status, and the Education Labor Market

    ERIC Educational Resources Information Center

    Evans, Lorraine

    2011-01-01

    This research explores the interaction between training programs and certification status in one education labor market to examine the micro-level interactions that shape the recruitment process. Using job queue theory, it is found that the information available to novice teachers operates to stratify and shape their worksite choices in addition…

  18. Generic Fortran Containers (GFC)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liakh, Dmitry

    2016-09-01

    The Fortran language does not provide a standard library that implements generic containers, like linked lists, trees, dictionaries, etc. The GFC software provides an implementation of generic Fortran containers natively written in Fortran 2003/2008 language. The following containers are either already implemented or planned: Stack (done), Linked list (done), Tree (done), Dictionary (done), Queue (planned), Priority queue (planned).

  19. Announcements | High-Performance Computing | NREL

    Science.gov Websites

    12th from 12 - 3 PM. Continue reading Data Transfer Queue March 08, 2018 A new queue "data , scratch) and MSS. Continue reading Purge-Alert January 11, 2018 We now have a notification method that . Continue reading Please Move Inactive Files Off the /projects File System January 11, 2018 The /projects

  20. Active Methodologies in a Queueing Systems Course for Telecommunication Engineering Studies

    ERIC Educational Resources Information Center

    Garcia, J.; Hernandez, A.

    2010-01-01

    This paper presents the results of a one-year experiment in incorporating active methodologies in a Queueing Systems course as part of the Telecommunication Engineering degree at the University of Zaragoza, Spain, during the period of adaptation to the European Higher Education Area. A problem-based learning methodology has been introduced, and…

  1. Techniques for Increasing the Efficiency of Automation Systems in School Library Media Centers.

    ERIC Educational Resources Information Center

    Caffarella, Edward P.

    1996-01-01

    Discusses methods of managing queues (waiting lines) to optimize the use of student computer stations in school library media centers and to make searches more efficient and effective. The three major factors in queue management are arrival interval of the patrons, service time, and number of stations. (Author/LRW)

  2. Performance modeling of automated manufacturing systems

    NASA Astrophysics Data System (ADS)

    Viswanadham, N.; Narahari, Y.

    A unified and systematic treatment is presented of modeling methodologies and analysis techniques for performance evaluation of automated manufacturing systems. The book is the first treatment of the mathematical modeling of manufacturing systems. Automated manufacturing systems are surveyed and three principal analytical modeling paradigms are discussed: Markov chains, queues and queueing networks, and Petri nets.

  3. Military Standard Common APSE (Ada Programming Support Environment) Interface Set (CAIS).

    DTIC Science & Technology

    1985-01-01

    QUEUEASE. LAST-KEY (QUEENAME) . LASTREI.TIONI(QUEUE-NAME). FILE-NODE. PORN . ATTRIBUTTES. ACCESSCONTROL. LEVEL); CLOSE (QUEUE BASE); CLOSE(FILE NODE...PROPOSED XIIT-STD-C.4 31 J NNUAfY logs procedure zTERT (ITERATOR: out NODE ITERATON; MAMIE: NAME STRING.KIND: NODE KID : KEY : RELATIONSHIP KEY PA1TTE1 :R

  4. 78 FR 20164 - Self-Regulatory Organizations; NYSE Arca, Inc.; Response to Comments Submitted After the Issuance...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-03

    ... data, views, and arguments concerning the Approval Order, including whether Amendment No. 1 to the... commenter discussed the existing unloading queues for metals, including copper, at LME warehouses.\\18\\ The commenter asserted that queues to unload copper from LME warehouses appear to be lengthening because owners...

  5. Entrainment of a Bacterial Synthetic Gene Oscillator through Proteolytic Queueing.

    PubMed

    Butzin, Nicholas C; Hochendoner, Philip; Ogle, Curtis T; Mather, William H

    2017-03-17

    Internal chemical oscillators (chemical clocks) direct the behavior of numerous biological systems, and maintenance of a given period and phase among many such oscillators may be important for their proper function. However, both environmental variability and fundamental molecular noise can cause biochemical oscillators to lose coherence. One solution to maintaining coherence is entrainment, where an external signal provides a cue that resets the phase of the oscillators. In this work, we study the entrainment of gene networks by a queueing interaction established by competition between proteins for a common proteolytic pathway. Principles of queueing entrainment are investigated for an established synthetic oscillator in Escherichia coli. We first explore this theoretically using a standard chemical reaction network model and a map-based model, both of which suggest that queueing entrainment can be achieved through pulsatile production of an additional protein competing for a common degradation pathway with the oscillator proteins. We then use a combination of microfluidics and fluorescence microscopy to verify that pulse trains modulating the production rate of a fluorescent protein targeted to the same protease (ClpXP) as the synthetic oscillator can entrain the oscillator.

  6. Static analysis of the hull plate using the finite element method

    NASA Astrophysics Data System (ADS)

    Ion, A.

    2015-11-01

    This paper aims at presenting the static analysis for two levels of a container ship's construction as follows: the first level is at the girder / hull plate and the second level is conducted at the entire strength hull of the vessel. This article will describe the work for the static analysis of a hull plate. We shall use the software package ANSYS Mechanical 14.5. The program is run on a computer with four Intel Xeon X5260 CPU processors at 3.33 GHz, 32 GB memory installed. In terms of software, the shared memory parallel version of ANSYS refers to running ANSYS across multiple cores on a SMP system. The distributed memory parallel version of ANSYS (Distributed ANSYS) refers to running ANSYS across multiple processors on SMP systems or DMP systems.

  7. VLSI 'smart' I/O module development

    NASA Astrophysics Data System (ADS)

    Kirk, Dan

    The developmental history, design, and operation of the MIL-STD-1553A/B discrete and serial module (DSM) for the U.S. Navy AN/AYK-14(V) avionics computer are described and illustrated with diagrams. The ongoing preplanned product improvement for the AN/AYK-14(V) includes five dual-redundant MIL-STD-1553 channels based on DSMs. The DSM is a front-end processor for transferring data to and from a common memory, sharing memory with a host processor to provide improved 'smart' input/output performance. Each DSM comprises three hardware sections: three VLSI-6000 semicustomized CMOS arrays, memory units to support the arrays, and buffers and resynchronization circuits. The DSM hardware module design, VLSI-6000 design tools, controlware and test software, and checkout procedures (using a hardware simulator) are characterized in detail.

  8. HeinzelCluster: accelerated reconstruction for FORE and OSEM3D.

    PubMed

    Vollmar, S; Michel, C; Treffert, J T; Newport, D F; Casey, M; Knöss, C; Wienhard, K; Liu, X; Defrise, M; Heiss, W D

    2002-08-07

    Using iterative three-dimensional (3D) reconstruction techniques for reconstruction of positron emission tomography (PET) is not feasible on most single-processor machines due to the excessive computing time needed, especially so for the large sinogram sizes of our high-resolution research tomograph (HRRT). In our first approach to speed up reconstruction time we transform the 3D scan into the format of a two-dimensional (2D) scan with sinograms that can be reconstructed independently using Fourier rebinning (FORE) and a fast 2D reconstruction method. On our dedicated reconstruction cluster (seven four-processor systems, Intel PIII@700 MHz, switched fast ethernet and Myrinet, Windows NT Server), we process these 2D sinograms in parallel. We have achieved a speedup > 23 using 26 processors and also compared results for different communication methods (RPC, Syngo, Myrinet GM). The other approach is to parallelize OSEM3D (implementation of C Michel), which has produced the best results for HRRT data so far and is more suitable for an adequate treatment of the sinogram gaps that result from the detector geometry of the HRRT. We have implemented two levels of parallelization for four dedicated cluster (a shared memory fine-grain level on each node utilizing all four processors and a coarse-grain level allowing for 15 nodes) reducing the time for one core iteration from over 7 h to about 35 min.

  9. File Transfers from Peregrine to the Mass Storage System - Gyrfalcon |

    Science.gov Websites

    login node or data-transfer queue node. Below is an example to access data-tranfer queue Interactively number of container files using the tar command. For example, $ cd /scratch//directory1 tar files. The rsync command is convenient for handling a large number of files. For example, make

  10. An Empirical Study of the Career Paths of Senior Educational Administrators in Manitoba, Canada: Implications for Career Development

    ERIC Educational Resources Information Center

    Wallin, Dawn C.

    2012-01-01

    This paper conceptualizes queue theory (Tallerico & Blount, 2004) to discuss a mixed-methods study that determined the career patterns of senior educational administrators in public school divisions in Manitoba, Canada, compared by position, context and sex. Findings indicate that queue theory has merit for describing the career paths of…

  11. Preventing Bandwidth Abuse at the Router through Sending Rate Estimate-based Active Queue Management

    DTIC Science & Technology

    2007-06-01

    behavior is growing in the Internet. These non-responsive sources can monopolize network bandwidth and starve the “congestion friendly” flows. Without...unnecessarily complex because most of the flows in the Internet are short flows usually termed as “web mice ” [7]. Moreover, having a separate queue for each

  12. Self-organization of critical behavior in controlled general queueing models

    NASA Astrophysics Data System (ADS)

    Blanchard, Ph.; Hongler, M.-O.

    2004-03-01

    We consider general queueing models of the (G/G/1) type with service times controlled by the busy period. For feedback control mechanisms driving the system to very high traffic load, it is shown the busy period probability density exhibits a generic - {3}/{2} power law which is a typical mean field behavior of SOC models.

  13. SweeD: likelihood-based detection of selective sweeps in thousands of genomes.

    PubMed

    Pavlidis, Pavlos; Živkovic, Daniel; Stamatakis, Alexandros; Alachiotis, Nikolaos

    2013-09-01

    The advent of modern DNA sequencing technology is the driving force in obtaining complete intra-specific genomes that can be used to detect loci that have been subject to positive selection in the recent past. Based on selective sweep theory, beneficial loci can be detected by examining the single nucleotide polymorphism patterns in intraspecific genome alignments. In the last decade, a plethora of algorithms for identifying selective sweeps have been developed. However, the majority of these algorithms have not been designed for analyzing whole-genome data. We present SweeD (Sweep Detector), an open-source tool for the rapid detection of selective sweeps in whole genomes. It analyzes site frequency spectra and represents a substantial extension of the widely used SweepFinder program. The sequential version of SweeD is up to 22 times faster than SweepFinder and, more importantly, is able to analyze thousands of sequences. We also provide a parallel implementation of SweeD for multi-core processors. Furthermore, we implemented a checkpointing mechanism that allows to deploy SweeD on cluster systems with queue execution time restrictions, as well as to resume long-running analyses after processor failures. In addition, the user can specify various demographic models via the command-line to calculate their theoretically expected site frequency spectra. Therefore, (in contrast to SweepFinder) the neutral site frequencies can optionally be directly calculated from a given demographic model. We show that an increase of sample size results in more precise detection of positive selection. Thus, the ability to analyze substantially larger sample sizes by using SweeD leads to more accurate sweep detection. We validate SweeD via simulations and by scanning the first chromosome from the 1000 human Genomes project for selective sweeps. We compare SweeD results with results from a linkage-disequilibrium-based approach and identify common outliers.

  14. Multiserver Queueing Model subject to Single Exponential Vacation

    NASA Astrophysics Data System (ADS)

    Vijayashree, K. V.; Janani, B.

    2018-04-01

    A multi-server queueing model subject to single exponential vacation is considered. The arrivals are allowed to join the queue according to a Poisson distribution and services takes place according to an exponential distribution. Whenever the system becomes empty, all the servers goes for a vacation and returns back after a fixed interval of time. The servers then starts providing service if there are waiting customers otherwise they will wait to complete the busy period. The vacation times are also assumed to be exponentially distributed. In this paper, the stationary and transient probabilities for the number of customers during ideal and functional state of the server are obtained explicitly. Also, numerical illustrations are added to visualize the effect of various parameters.

  15. Nursing home queues and home health users.

    PubMed

    Swan, J H; Benjamin, A E

    1993-01-01

    Home health market growth suggests the need for models explaining home health utilization. We have previously explained state-level Medicare home health visits with reference to nursing home markets. Here we introduce a model whereby state-level Medicare home health use is a function of nursing home queues and other demand and supply factors. Medicare home health users per state population is negatively related to nursing home bed stock, positively to Medicaid eligibility levels and to Medicaid nursing home recipients per population, as well as to various other demand and supply measures. This explanation of home health users explains previously-reported findings for home health visits. The findings support the argument that home health use is explained by factors affecting lengths of nursing home queues.

  16. Improved diagonal queue medical image steganography using Chaos theory, LFSR, and Rabin cryptosystem.

    PubMed

    Jain, Mamta; Kumar, Anil; Choudhary, Rishabh Charan

    2017-06-01

    In this article, we have proposed an improved diagonal queue medical image steganography for patient secret medical data transmission using chaotic standard map, linear feedback shift register, and Rabin cryptosystem, for improvement of previous technique (Jain and Lenka in Springer Brain Inform 3:39-51, 2016). The proposed algorithm comprises four stages, generation of pseudo-random sequences (pseudo-random sequences are generated by linear feedback shift register and standard chaotic map), permutation and XORing using pseudo-random sequences, encryption using Rabin cryptosystem, and steganography using the improved diagonal queues. Security analysis has been carried out. Performance analysis is observed using MSE, PSNR, maximum embedding capacity, as well as by histogram analysis between various Brain disease stego and cover images.

  17. Low-traffic limit and first-passage times for a simple model of the continuous double auction

    NASA Astrophysics Data System (ADS)

    Scalas, Enrico; Rapallo, Fabio; Radivojević, Tijana

    2017-11-01

    We consider a simplified model of the continuous double auction where prices are integers varying from 1 to N with limit orders and market orders, but quantity per order limited to a single share. For this model, the order process is equivalent to two M / M / 1 queues. We study the behavior of the auction in the low-traffic limit where limit orders are immediately matched by market orders. In this limit, the distribution of prices can be computed exactly and gives a reasonable approximation of the price distribution when the ratio between the rate of order arrivals and the rate of order executions is below 1 / 2. This is further confirmed by the analysis of the first-passage time in 1 or N.

  18. Secure Embedded System Design Methodologies for Military Cryptographic Systems

    DTIC Science & Technology

    2016-03-31

    Fault- Tree Analysis (FTA); Built-In Self-Test (BIST) Introduction Secure access-control systems restrict operations to authorized users via methods...failures in the individual software/processor elements, the question of exactly how unlikely is difficult to answer. Fault- Tree Analysis (FTA) has a...Collins of Sandia National Laboratories for years of sharing his extensive knowledge of Fail-Safe Design Assurance and Fault- Tree Analysis

  19. Digital Collaboration Tools in the Military: Their Historical and Current Status

    DTIC Science & Technology

    2006-02-16

    Writer = online word processor that edits, stores and shares your documents from anywhere. February 16, 2006 31 Recent “ Disruptive ” Technologies Cell...Webcasts Wikis February 16, 2006 32 Now Consider: Disruptive Technologies (1997) becomes Disruptive Innovations in 2003. Military Transformation: Drivers...from http://www.sims.berkeley.edu/how-much-info-2003 Schneiderman, R. (2005). Preparing for the Disruptive Technologies of Tomorrow. http

  20. Distributed Systems Technology Survey.

    DTIC Science & Technology

    1987-03-01

    and prolocols. 2. Hardware Technology Ecnomic factor we a majo reonm for the prolierat of dlstbted systoe. Processors, memory, an magne tc ndoptical...destined messages and pertorn the a pro te forwarding. There gImsno agreement that a ightweight process mechanism is essential to support com- monly used...Xerox PARC environment [311. Shared file servers, discussed below, are essential to the success of such a scheme. 11. ecurlity A distributed

  1. Introduction

    NASA Astrophysics Data System (ADS)

    de Laat, Cees; Develder, Chris; Jukan, Admela; Mambretti, Joe

    This topic is devoted to communication issues in scalable compute and storage systems, such as parallel computers, networks of workstations, and clusters. All aspects of communication in modern systems were solicited, including advances in the design, implementation, and evaluation of interconnection networks, network interfaces, system and storage area networks, on-chip interconnects, communication protocols, routing and communication algorithms, and communication aspects of parallel and distributed algorithms. In total 15 papers were submitted to this topic of which we selected the 7 strongest papers. We grouped the papers in two sessions of 3 papers each and one paper was selected for the best paper session. We noted a number of papers dealing with changing topologies, stability and forwarding convergence in source routing based cluster interconnect network architectures. We grouped these for the first session. The authors of the paper titled: “Implementing a Change Assimilation Mechanism for Source Routing Interconnects” propose a mechanism that can obtain the new topology, and compute and distribute a new set of fabric paths to the source routed network end points to minimize the impact on the forwarding service. The article entitled “Dependability Analysis of a Fault-tolerant Network Reconfiguration Strateg” reports on a case study analyzing the effects of network size, mean time to node failure, mean time to node repair, mean time to network repair and coverage of the failure when using a 2D mesh network with a fault-tolerant mechanism (similar to the one used in the BlueGene/L system), that is able to remove rows and/or columns in the presence of failures. The last paper in this session: “RecTOR: A New and Efficient Method for Dynamic Network Reconfiguration” presents a new dynamic reconfiguration method, that ensures deadlock-freedom during the reconfiguration without causing performance degradation such as increased latency or decreased throughput. The second session groups 3 papers presenting methods, protocols and architectures that enhance capacities in the Networks. The paper titled: “NIC-assisted Cache-Efficient Receive Stack for Message Passing over Ethernet” presents the addition of multiqueue support in the Open-MX receive stack so that all incoming packets for the same process are treated on the same core. It then introduces the idea of binding the target end process near its dedicated receive queue. In general this multiqueue receive stack performs better than the original single queue stack, especially on large communication patterns where multiple processes are involved and manual binding is difficult. The authors of: “A Multipath Fault-Tolerant Routing Method for High-Speed Interconnection Networks” focus on the problem of fault tolerance for high-speed interconnection networks by designing a fault tolerant routing method. The goal was to solve a certain number of link and node failures, considering its impact, and occurrence probability. Their experiments show that their method allows applications to successfully finalize their execution in the presence of several faults, with an average performance value of 97% with respect to the fault-free scenarios. The paper: “Hardware implementation study of the Self-Clocked Fair Queuing Credit Aware (SCFQ-CA) and Deficit Round Robin Credit Aware (DRR-CA) scheduling algorithms” proposes specific implementations of the two schedulers taking into account the characteristics of current high-performance networks. A comparison is presented on the complexity of these two algorithms in terms of silicon area and computation delay. Finally we selected one paper for the special paper session: “A Case Study of Communication Optimizations on 3D Mesh Interconnects”. In this paper the authors present topology aware mapping as a technique to optimize communication on 3-dimensional mesh interconnects and hence improve performance. Results are presented for OpenAtom on up to 16,384 processors of Blue Gene/L, 8,192 processors of Blue Gene/P and 2,048 processors of Cray XT3.

  2. Ion propulsion cost effectivity

    NASA Technical Reports Server (NTRS)

    Zafran, S.; Biess, J. J.

    1978-01-01

    Ion propulsion modules employing 8-cm thrusters and 30-cm thrusters were studied for Multimission Modular Spacecraft (MMS) applications. Recurring and nonrecurring cost elements were generated for these modules. As a result, ion propulsion cost drivers were identified to be Shuttle charges, solar array, power processing, and thruster costs. Cost effective design approaches included short length module configurations, array power sharing, operation at reduced thruster input power, simplified power processing units, and power processor output switching. The MMS mission model employed indicated that nonrecurring costs have to be shared with other programs unless the mission model grows. Extended performance missions exhibited the greatest benefits when compared with monopropellant hydrazine propulsion.

  3. Lightweight active router-queue management for multimedia networking

    NASA Astrophysics Data System (ADS)

    Parris, Mark; Jeffay, Kevin; Smith, F. D.

    1998-12-01

    The Internet research community is promoting active queue management in routers as a proactive means of addressing congestion in the Internet. Active queue management mechanisms such as Random Early Detection (RED) work well for TCP flows but can fail in the presence of unresponsive UDP flows. Recent proposals extend RED to strongly favor TCP and TCP-like flows and to actively penalize `misbehaving' flows. This is problematic for multimedia flows that, although potentially well-behaved, do not, or can not, satisfy the definition of a TCP-like flow. In this paper we investigate an extension to RED active queue management called Class-Based Thresholds (CBT). The goal of CBT is to reduce congestion in routers and to protect TCP from all UDP flows while also ensuring acceptable throughput and latency for well-behaved UDP flows. CBT attempts to realize a `better than best effort' service for well-behaved multimedia flows that is comparable to that achieved by a packet or link scheduling discipline, however, CBT does this by queue management rather than by scheduling. We present results of experiments comparing our mechanisms to plain RED and to FRED, a variant of RED designed to ensure fair allocation of bandwidth amongst flows. We also compare CBT to a packet scheduling scheme. The experiments show that CBT (1) realizes protection for TCP, and (2) provides throughput and end-to-end latency for tagged UDP flows, that is better than that under FRED and RED and comparable to that achieved by packet scheduling. Moreover CBT is a lighter-weight mechanism than FRED in terms of its state requirements and implementation complexity.

  4. Solving the negative impact of congestion in the postanesthesia care unit: a cost of opportunity analysis.

    PubMed

    Ruiz-Patiño, Alejandro; Acosta-Ospina, Laura Elena; Rueda, Juan-David

    2017-04-01

    Congestion in the postanesthesia care unit (PACU) leads to the formation of waiting queues for patients being transferred after surgery, negatively affecting hospital resources. As patients recover in the operating room, incoming surgeries are delayed. The purpose of this study was to establish the impact of this phenomenon in multiple settings. An operational mathematical study based on the queuing theory was performed. Average queue length, average queue waiting time, and daily queue waiting time were evaluated. Calculations were based on the mean patient daily flow, PACU length of stay, occupation, and current number of beds. Data was prospectively collected during a period of 2 months, and the entry and exit time was recorded for each patient taken to the PACU. Data was imputed in a computational model made with MS Excel. To account for data uncertainty, deterministic and probabilistic sensitivity analyses for all dependent variables were performed. With a mean patient daily flow of 40.3 and an average PACU length of stay of 4 hours, average total lost surgical opportunity time was estimated at 2.36 hours (95% CI: 0.36-4.74 hours). Cost of opportunity was calculated at $1592 per lost hour. Sensitivity analysis showed that an increase of two beds is required to solve the queue formation. When congestion has a negative impact on cost of opportunity in the surgical setting, queuing analysis grants definitive actions to solve the problem, improving quality of service and resource utilization. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Intel Parallel Studio on the Peregrine System | High-Performance Computing

    Science.gov Websites

    given below: #!/bin/bash --login #PBS -N #PBS -q #PBS -l nodes=<N> ;:ppn=<n> #PBS -l walltime=00:30:00 #PBS -A # set your tmpdir, and don't collect MPI communication data: #!/bin/bash --login #PBS -N #PBS -q #PBS -l

  6. A queueing network model to analyze the impact of parallelization of care on patient cycle time.

    PubMed

    Jiang, Lixiang; Giachetti, Ronald E

    2008-09-01

    The total time a patient spends in an outpatient facility, called the patient cycle time, is a major contributor to overall patient satisfaction. A frequently recommended strategy to reduce the total time is to perform some activities in parallel thereby shortening patient cycle time. To analyze patient cycle time this paper extends and improves upon existing multi-class open queueing network model (MOQN) so that the patient flow in an urgent care center can be modeled. Results of the model are analyzed using data from an urgent care center contemplating greater parallelization of patient care activities. The results indicate that parallelization can reduce the cycle time for those patient classes which require more than one diagnostic and/ or treatment intervention. However, for many patient classes there would be little if any improvement, indicating the importance of tools to analyze business process reengineering rules. The paper makes contributions by implementing an approximation for fork/join queues in the network and by improving the approximation for multiple server queues in both low traffic and high traffic conditions. We demonstrate the accuracy of the MOQN results through comparisons to simulation results.

  7. A Parallel Rendering Algorithm for MIMD Architectures

    NASA Technical Reports Server (NTRS)

    Crockett, Thomas W.; Orloff, Tobias

    1991-01-01

    Applications such as animation and scientific visualization demand high performance rendering of complex three dimensional scenes. To deliver the necessary rendering rates, highly parallel hardware architectures are required. The challenge is then to design algorithms and software which effectively use the hardware parallelism. A rendering algorithm targeted to distributed memory MIMD architectures is described. For maximum performance, the algorithm exploits both object-level and pixel-level parallelism. The behavior of the algorithm is examined both analytically and experimentally. Its performance for large numbers of processors is found to be limited primarily by communication overheads. An experimental implementation for the Intel iPSC/860 shows increasing performance from 1 to 128 processors across a wide range of scene complexities. It is shown that minimal modifications to the algorithm will adapt it for use on shared memory architectures as well.

  8. General-purpose interface bus for multiuser, multitasking computer system

    NASA Technical Reports Server (NTRS)

    Generazio, Edward R.; Roth, Don J.; Stang, David B.

    1990-01-01

    The architecture of a multiuser, multitasking, virtual-memory computer system intended for the use by a medium-size research group is described. There are three central processing units (CPU) in the configuration, each with 16 MB memory, and two 474 MB hard disks attached. CPU 1 is designed for data analysis and contains an array processor for fast-Fourier transformations. In addition, CPU 1 shares display images viewed with the image processor. CPU 2 is designed for image analysis and display. CPU 3 is designed for data acquisition and contains 8 GPIB channels and an analog-to-digital conversion input/output interface with 16 channels. Up to 9 users can access the third CPU simultaneously for data acquisition. Focus is placed on the optimization of hardware interfaces and software, facilitating instrument control, data acquisition, and processing.

  9. Performance prediction: A case study using a multi-ring KSR-1 machine

    NASA Technical Reports Server (NTRS)

    Sun, Xian-He; Zhu, Jianping

    1995-01-01

    While computers with tens of thousands of processors have successfully delivered high performance power for solving some of the so-called 'grand-challenge' applications, the notion of scalability is becoming an important metric in the evaluation of parallel machine architectures and algorithms. In this study, the prediction of scalability and its application are carefully investigated. A simple formula is presented to show the relation between scalability, single processor computing power, and degradation of parallelism. A case study is conducted on a multi-ring KSR1 shared virtual memory machine. Experimental and theoretical results show that the influence of topology variation of an architecture is predictable. Therefore, the performance of an algorithm on a sophisticated, heirarchical architecture can be predicted and the best algorithm-machine combination can be selected for a given application.

  10. LLNL Genomic Assessment: Viral and Bacterial Sequencing Needs for TMTI, Tier 1 Report

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Slezak, T; Borucki, M; Lenhoff, R

    2009-09-29

    The Lawrence Livermore National Lab Bioinformatics group has recently taken on a role in DTRA's Transformation Medical Technologies Initiative (TMTI). The high-level goal of TMTI is to accelerate the development of broad-spectrum countermeasures. To achieve those goals, TMTI has a near term need to obtain more sequence information across a large range of pathogens, near neighbors, and across a broad geographical and host range. Our role in this project is to research available sequence data for the organisms of interest and identify critical microbial sequence and knowledge gaps that need to be filled to meet TMTI objectives. This effort includes:more » (1) assessing current genomic sequence for each agent including phylogenetic and geographical diversity, host range, date of isolation range, virulence, sequence availability of key near neighbors, and other characteristics; (2) identifying Subject Matter Experts (SME's) and potential holders of isolate collections, contacting appropriate SME's with known expertise and isolate collections to obtain information on isolate availability and specific recommendations; (3) identifying sequence as well as knowledge gaps (eg virulence, host range, and antibiotic resistance determinants); (4) providing specific recommendations as to the most valuable strains to be placed on the DTRA sequencing queue. We acknowledge that criteria for prioritization of isolates for sequencing falls into two categories aligning with priority queues 1 and 2 as described in the summary. (Priority queue 0 relates to DTRA operational isolates whose availability is not predictable in advance.) 1. Selection of isolates that appear to have likelihood to provide information on virulence and antibiotic resistance. This will include sequence of known virulent strains. Particularly valuable would be virulent strains that have genetically similar yet avirulent, or non human transmissible, counterparts that can be used for comparison to help identify key virulence or host range genes. This approach will provide information that can be used by structural biologists to help develop therapeutics and vaccines. We have pointed out such high priority strains of which we are aware, and note that if any such isolates should be discovered, they will rise to the top priority. We anticipate difficulty locating samples with unusual resistance phenotypes, in particular. Sequencing strategies for isolates in queue 1 should aim for as complete finishing status as possible, since high-quality initial annotation (gene-calling) will be necessary for the follow-on protein structure analyses contributing to countermeasure development. Queue 2 for sequencing determination will be more dynamic than queue 1, and samples will be added to it as they become available to the TMTI program. 2. Selection of isolates that will provide broader information about diversity and phylogenetics and aid in specific detection as well as forensics. This approach focuses on sequencing of isolates that will provide better resolution of variants that are (or were) circulating in nature. The finishing strategy for queue 2 does not require complete closing with annotation. This queue is more static, as there is considerable phylogenetic data, and in this report we have sought to reveal gaps and make suggestions to fill them given existing sequence data and strain information. In this report we identify current sequencing gaps in both priority queue categories. Note that this is most applicable to the bacterial pathogens, as most viruses are by default in queue 1. The Phase I focus of this project is on viral hemorrhagic fever viruses and Category A bacterial agents as defined to us by TMTI. We have carried out individual analyses on each species of interest, and these are included as chapters in this report. Viruses and bacteria are biologically very distinct from each other and require different methods of analysis and criteria for sequencing prioritization. Therefore, we will describe our methods, analyses and conclusions separately for each category.« less

  11. Effective ergodicity breaking in an exclusion process with varying system length

    NASA Astrophysics Data System (ADS)

    Schultens, Christoph; Schadschneider, Andreas; Arita, Chikashi

    2015-09-01

    Stochastic processes of interacting particles in systems with varying length are relevant e.g. for several biological applications. We try to explore what kind of new physical effects one can expect in such systems. As an example, we extend the exclusive queueing process that can be viewed as a one-dimensional exclusion process with varying length, by introducing Langmuir kinetics. This process can be interpreted as an effective model for a queue that interacts with other queues by allowing incoming and leaving of customers in the bulk. We find surprising indications for breaking of ergodicity in a certain parameter regime, where the asymptotic growth behavior depends on the initial length. We show that a random walk with site-dependent hopping probabilities exhibits qualitatively the same behavior.

  12. Queues and care: how medical residents organize their work in a busy clinic.

    PubMed

    Finlay, W; Mutran, E J; Zeitler, R R; Randall, C S

    1990-09-01

    How do medical residents organize their work in settings where queue demands are heavy and resources are limited? Under such conditions, a queue theory would predict the delivery of care that is indifferent to clients' needs or that gets rid of clients as quickly as possible. In an exploratory case study of medical residents in a Veterans Administration outpatient clinic, we found instead that the medical residents' work was characterized by a high level of professional commitment: they provided thorough medical examinations and attempted to expedite patient care in other ways. We attribute the residents' professional ethos to opportunities provided in the VA hospital to learn the craft of routine medicine and to be directly responsible for patient care; such opportunities were not available in other settings.

  13. Systolic array processing of the sequential decoding algorithm

    NASA Technical Reports Server (NTRS)

    Chang, C. Y.; Yao, K.

    1989-01-01

    A systolic array processing technique is applied to implementing the stack algorithm form of the sequential decoding algorithm. It is shown that sorting, a key function in the stack algorithm, can be efficiently realized by a special type of systolic arrays known as systolic priority queues. Compared to the stack-bucket algorithm, this approach is shown to have the advantages that the decoding always moves along the optimal path, that it has a fast and constant decoding speed and that its simple and regular hardware architecture is suitable for VLSI implementation. Three types of systolic priority queues are discussed: random access scheme, shift register scheme and ripple register scheme. The property of the entries stored in the systolic priority queue is also investigated. The results are applicable to many other basic sorting type problems.

  14. Realization of a single image haze removal system based on DaVinci DM6467T processor

    NASA Astrophysics Data System (ADS)

    Liu, Zhuang

    2014-10-01

    Video monitoring system (VMS) has been extensively applied in domains of target recognition, traffic management, remote sensing, auto navigation and national defence. However the VMS has a strong dependence on the weather, for instance, in foggy weather, the quality of images received by the VMS are distinct degraded and the effective range of VMS is also decreased. All in all, the VMS performs terribly in bad weather. Thus the research of fog degraded images enhancement has very high theoretical and practical application value. A design scheme of a fog degraded images enhancement system based on the TI DaVinci processor is presented in this paper. The main function of the referred system is to extract and digital cameras capture images and execute image enhancement processing to obtain a clear image. The processor used in this system is the dual core TI DaVinci DM6467T - ARM@500MHz+DSP@1GH. A MontaVista Linux operating system is running on the ARM subsystem which handles I/O and application processing. The DSP handles signal processing and the results are available to the ARM subsystem in shared memory.The system benefits from the DaVinci processor so that, with lower power cost and smaller volume, it provides the equivalent image processing capability of a X86 computer. The outcome shows that the system in this paper can process images at 25 frames per second on D1 resolution.

  15. The control data "GIRAFFE" system for interactive graphic finite element analysis

    NASA Technical Reports Server (NTRS)

    Park, S.; Brandon, D. M., Jr.

    1975-01-01

    The Graphical Interface for Finite Elements (GIRAFFE) general purpose interactive graphics application package was described. This system may be used as a pre/post processor for structural analysis computer programs. It facilitates the operations of creating, editing, or reviewing all the structural input/output data on a graphics terminal in a time-sharing mode of operation. An application program for a simple three-dimensional plate problem was illustrated.

  16. Information Extraction Using Controlled English to Support Knowledge-Sharing and Decision-Making

    DTIC Science & Technology

    2012-06-01

    or language variants. CE-based information extraction will greatly facilitate the processes in the cognitive and social domains that enable forces...terminology or language variants. CE-based information extraction will greatly facilitate the processes in the cognitive and social domains that...processor is run to turn the atomic CE into a more “ stylistically felicitous” CE, using techniques such as: aggregating all information about an entity

  17. Towards Scalable 1024 Processor Shared Memory Systems

    NASA Technical Reports Server (NTRS)

    Ciotti, Robert B.; Thigpen, William W. (Technical Monitor)

    2001-01-01

    Over the past 3 years, NASA Ames has been involved in a cooperative effort with SGI to develop the largest single system image systems available. Currently a 1024 Origin3OOO is under development, with first boot expected later in the summer of 2001. This paper discusses some early results with a 512p Origin3OOO system and some arcane IRIX system calls that can dramatically improve scaling performance.

  18. Parallel Programming Paradigms

    DTIC Science & Technology

    1987-07-01

    Unclassified IS.. DECLASSIFICATIONIOOWNGRADIN G 16. DISTRIBUTION STATEMENT (of this Report) Distribution of this report is unlimited. 17...8416878 and by the Office of Naval Research Contracts No. N00014-86-K-0264 and No. N00014-85- K-0328. 8 ?~~ O . G 1 49 II Parallel Programming Paradigms...processors -. "to fetch from the same memory cell (list head) and thus seems to favor a shared memory - g implementation [37). In this dissertation, we

  19. Comparison of a Visual and Head Tactile Display for Soldier Navigation

    DTIC Science & Technology

    2013-12-01

    environments for nuclear power plant operators, air traffic controllers, and pilots are information intensive. These environments usually involve the indirect...queue, correcting aircraft conflicts, giving instruction, clearance and advice to pilots , and assigning aircrafts to other work queues and airports...these dynamic, complex, and multitask environments (1) collect and integrate a plethora of visual information into decisions that are critical for

  20. A queueing model of pilot decision making in a multi-task flight management situation

    NASA Technical Reports Server (NTRS)

    Walden, R. S.; Rouse, W. B.

    1977-01-01

    Allocation of decision making responsibility between pilot and computer is considered and a flight management task, designed for the study of pilot-computer interaction, is discussed. A queueing theory model of pilot decision making in this multi-task, control and monitoring situation is presented. An experimental investigation of pilot decision making and the resulting model parameters are discussed.

  1. Optimizing Crisis Action Planning in the Noncombatant Evacuation Operation Setting

    DTIC Science & Technology

    2010-06-01

    Federal Regulations, the DoS has a firm rule to not enter into preemptive contracts for any logistical resources (e.g., transportation, food, water...bottlenecks, flow limiters, and options to quicken queues ; and identifying resources and transportation mediums that display the most sensitivity to...policy changes. These objectives were addressed by exploring topics in NEOs, evacuation planning, queueing systems, and modeling techniques and

  2. Efficient Approximation Algorithms for Weighted $b$-Matching

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Khan, Arif; Pothen, Alex; Mostofa Ali Patwary, Md.

    2016-01-01

    We describe a half-approximation algorithm, b-Suitor, for computing a b-Matching of maximum weight in a graph with weights on the edges. b-Matching is a generalization of the well-known Matching problem in graphs, where the objective is to choose a subset of M edges in the graph such that at most a specified number b(v) of edges in M are incident on each vertex v. Subject to this restriction we maximize the sum of the weights of the edges in M. We prove that the b-Suitor algorithm computes the same b-Matching as the one obtained by the greedy algorithm for themore » problem. We implement the algorithm on serial and shared-memory parallel processors, and compare its performance against a collection of approximation algorithms that have been proposed for the Matching problem. Our results show that the b-Suitor algorithm outperforms the Greedy and Locally Dominant edge algorithms by one to two orders of magnitude on a serial processor. The b-Suitor algorithm has a high degree of concurrency, and it scales well up to 240 threads on a shared memory multiprocessor. The b-Suitor algorithm outperforms the Locally Dominant edge algorithm by a factor of fourteen on 16 cores of an Intel Xeon multiprocessor.« less

  3. Individual dispersal delays in a cooperative breeder: Ecological constraints, the benefits of philopatry and the social queue for dominance.

    PubMed

    Nelson-Flower, Martha J; Wiley, Elizabeth M; Flower, Tom P; Ridley, Amanda R

    2018-03-20

    Delayed dispersal is a key step in the evolution of familial animal societies and cooperative breeding. However, no consensus has been reached on the ecological and social circumstances driving delayed dispersal. Here, we test predictions from the ecological constraints and benefits of philopatry hypotheses as well as the recently proposed dual benefits hypothesis to better understand the evolution of group-living and cooperative breeding. Furthermore, we consider how individual social circumstances within groups affect dispersal decisions. We examine 11 years of life-history information on a wild population of cooperatively breeding southern pied babblers Turdoides bicolor. We investigate the effects of ecological conditions, natal-group membership and individual social context on male and female dispersal delays, disperser survival and acquisition of dominance. Female dispersal decisions are generally unconstrained by ecological or social circumstances. In contrast, males disperse in response to relaxed ecological constraints, decreases in nepotistic tolerance or when low social rank in the queue for dominance decreases their likelihood of gaining a dominant breeding position. Early dispersal by end-of-queue males often leads to a head-of-queue subordinate position in a non-natal group, thereby increasing access to dominant breeding positions. However, males and females remaining in natal groups gain benefits of philopatry via increased survival and, for head-of-queue males, very high likelihood of acquisition of a breeding position. Overall, predictions from the dual benefits hypothesis best describe these results, while some predictions from each of the ecological constraints and benefits of philopatry hypotheses were supported. The benefits of living and working together (collective action benefits) in large stable groups are of central importance in shaping dispersal delays in southern pied babbler societies. In addition, position in the subordinate social queue for dominance is the key in determining access to reproduction, particularly for males. This research highlights the importance of considering the costs and benefits of individual social circumstances in dispersal decisions and illustrates how the dual benefits hypothesis offers new perspectives in understanding delayed dispersal. © 2018 The Authors. Journal of Animal Ecology © 2018 British Ecological Society.

  4. Queue position in the endoscopic schedule impacts effectiveness of colonoscopy.

    PubMed

    Lee, Alexander; Iskander, John M; Gupta, Nitin; Borg, Brian B; Zuckerman, Gary; Banerjee, Bhaskar; Gyawali, C Prakash

    2011-08-01

    Endoscopist fatigue potentially impacts colonoscopy. Fatigue is difficult to quantitate, but polyp detection rates between non-fatigued and fatigued time periods could represent a surrogate marker. We assessed whether timing variables impacted polyp detection rates at a busy tertiary care endoscopy suite. Consecutive patients undergoing colonoscopy were retrospectively identified. Indications, clinical demographics, pre-procedural, and procedural variables were extracted from chart review; colonoscopy findings were determined from the procedure reports. Three separate timing variables were assessed as surrogate markers for endoscopist fatigue: morning vs. afternoon procedures, start times throughout the day, and queue position, a unique variable that takes into account the number of procedures performed before the colonoscopy of interest. Univariate and multivariate analyses were performed to determine whether timing variables and other clinical, pre-procedural, and procedural variables predicted polyp detection. During the 4-month study period, 1,083 outpatient colonoscopy procedures (57.5±0.5 years, 59.5% female) were identified, performed by 28 endoscopists (mean 38.7 procedures/endoscopist), with a mean polyp detection rate of 0.851/colonoscopy. At least, one adenoma was detected in 297 procedures (27.4%). A 12.4% reduction in mean detected polyps was detected between morning and afternoon procedures (0.90±0.06 vs. 0.76±0.06, P=0.15). Using start time on a continuous scale, however, each elapsed hour in the day was associated with a 4.6% reduction in polyp detection (P=0.005). When queue position was assessed, a 5.4% reduction in polyp detection was noted with each increase in queue position (P=0.016). These results remained significant when controlled for each individual endoscopist. Polyp detection rates decline as time passes during an endoscopist's schedule, potentially from endoscopist fatigue. Queue position may be a novel surrogate measure for operator fatigue.

  5. Applying a foil queue micro-electrode in micro-EDM to fabricate a 3D micro-structure

    NASA Astrophysics Data System (ADS)

    Xu, Bin; Guo, Kang; Wu, Xiao-yu; Lei, Jian-guo; Liang, Xiong; Guo, Deng-ji; Ma, Jiang; Cheng, Rong

    2018-05-01

    Applying a 3D micro-electrode in a micro electrical discharge machining (micro-EDM) can fabricate a 3D micro-structure with an up and down reciprocating method. However, this processing method has some shortcomings, such as a low success rate and a complex process for fabrication of 3D micro-electrodes. By focusing on these shortcomings, this paper proposed a novel 3D micro-EDM process based on the foil queue micro-electrode. Firstly, a 3D micro-electrode was discretized into several foil micro-electrodes and these foil micro-electrodes constituted a foil queue micro-electrode. Then, based on the planned process path, foil micro-electrodes were applied in micro-EDM sequentially and the micro-EDM results of each foil micro-electrode were able to superimpose the 3D micro-structure. However, the step effect will occur on the 3D micro-structure surface, which has an adverse effect on the 3D micro-structure. To tackle this problem, this paper proposes to reduce this adverse effect by rounded corner wear at the end of the foil micro-electrode and studies the impact of machining parameters on rounded corner wear and the step effect on the micro-structure surface. Finally, using a wire cutting voltage of 80 V, a current of 0.5 A and a pulse width modulation ratio of 1:4, the foil queue micro-electrode was fabricated by wire electrical discharge machining. Also, using a pulse width of 100 ns, a pulse interval of 200 ns, a voltage of 100 V and workpiece material of 304# stainless steel, the foil queue micro-electrode was applied in micro-EDM for processing of a 3D micro-structure with hemispherical features, which verified the feasibility of this process.

  6. Multi-protocol header generation system

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Roberts, David A.; Ignatowski, Michael; Jayasena, Nuwan

    A communication device includes a data source that generates data for transmission over a bus, and a data encoder that receives and encodes outgoing data. An encoder system receives outgoing data from a data source and stores the outgoing data in a first queue. An encoder encodes outgoing data with a header type that is based upon a header type indication from a controller and stores the encoded data that may be a packet or a data word with at least one layered header in a second queue for transmission. The device is configured to receive at a payload extractor,more » a packet protocol change command from the controller and to remove the encoded data and to re-encode the data to create a re-encoded data packet and placing the re-encoded data packet in the second queue for transmission.« less

  7. Capacity-constrained traffic assignment in networks with residual queues

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lam, W.H.K.; Zhang, Y.

    2000-04-01

    This paper proposes a capacity-constrained traffic assignment model for strategic transport planning in which the steady-state user equilibrium principle is extended for road networks with residual queues. Therefore, the road-exit capacity and the queuing effects can be incorporated into the strategic transport model for traffic forecasting. The proposed model is applicable to the congested network particularly when the traffic demands exceeds the capacity of the network during the peak period. An efficient solution method is proposed for solving the steady-state traffic assignment problem with residual queues. Then a simple numerical example is employed to demonstrate the application of the proposedmore » model and solution method, while an example of a medium-sized arterial highway network in Sioux Falls, South Dakota, is used to test the applicability of the proposed solution to real problems.« less

  8. A new intuitionistic fuzzy rule-based decision-making system for an operating system process scheduler.

    PubMed

    Butt, Muhammad Arif; Akram, Muhammad

    2016-01-01

    We present a new intuitionistic fuzzy rule-based decision-making system based on intuitionistic fuzzy sets for a process scheduler of a batch operating system. Our proposed intuitionistic fuzzy scheduling algorithm, inputs the nice value and burst time of all available processes in the ready queue, intuitionistically fuzzify the input values, triggers appropriate rules of our intuitionistic fuzzy inference engine and finally calculates the dynamic priority (dp) of all the processes in the ready queue. Once the dp of every process is calculated the ready queue is sorted in decreasing order of dp of every process. The process with maximum dp value is sent to the central processing unit for execution. Finally, we show complete working of our algorithm on two different data sets and give comparisons with some standard non-preemptive process schedulers.

  9. MPF: A portable message passing facility for shared memory multiprocessors

    NASA Technical Reports Server (NTRS)

    Malony, Allen D.; Reed, Daniel A.; Mcguire, Patrick J.

    1987-01-01

    The design, implementation, and performance evaluation of a message passing facility (MPF) for shared memory multiprocessors are presented. The MPF is based on a message passing model conceptually similar to conversations. Participants (parallel processors) can enter or leave a conversation at any time. The message passing primitives for this model are implemented as a portable library of C function calls. The MPF is currently operational on a Sequent Balance 21000, and several parallel applications were developed and tested. Several simple benchmark programs are presented to establish interprocess communication performance for common patterns of interprocess communication. Finally, performance figures are presented for two parallel applications, linear systems solution, and iterative solution of partial differential equations.

  10. Reducing Interprocessor Dependence in Recoverable Distributed Shared Memory

    NASA Technical Reports Server (NTRS)

    Janssens, Bob; Fuchs, W. Kent

    1994-01-01

    Checkpointing techniques in parallel systems use dependency tracking and/or message logging to ensure that a system rolls back to a consistent state. Traditional dependency tracking in distributed shared memory (DSM) systems is expensive because of high communication frequency. In this paper we show that, if designed correctly, a DSM system only needs to consider dependencies due to the transfer of blocks of data, resulting in reduced dependency tracking overhead and reduced potential for rollback propagation. We develop an ownership timestamp scheme to tolerate the loss of block state information and develop a passive server model of execution where interactions between processors are considered atomic. With our scheme, dependencies are significantly reduced compared to the traditional message-passing model.

  11. Content Dynamics Over the Network Cloud

    DTIC Science & Technology

    2015-11-04

    Ferragut, “Trading Off Efficiency and Reciprocity in Wireless Peer- To-Peer File Sharing”, WiOpt 2015, Mumbai , India, May 2015. 11. A. Ferragut, F...inspired by queueing theory”, RSRG Seminar, Caltech, March 2015. q) Presentation of paper [10] by the PI at WiOpt, Mumbai , India, May 2015...2015, Mumbai , India, May 2015. 11. A. Ferragut, F. Paganini, "Queueing analysis of peer-to-peer swarms: stationary distributions and their scaling

  12. Improving Aircraft Refueling Procedures at Naval Air Station Oceana

    DTIC Science & Technology

    2012-06-01

    Station (NAS) Oceana, VA, using aircraft waiting time for fuel as a measure of performance. We develop a computer-assisted discrete-event simulation to...Station (NAS) Oceana, VA, using aircraft waiting time for fuel as a measure of performance. We develop a computer-assisted discrete-event simulation...server queue, with general interarrival and service time distributions gpm Gallons per minute JDK Java development kit M/M/1 Single-server queue

  13. Using Markov Decision Processes with Heterogeneous Queueing Systems to Examine Military MEDEVAC Dispatching Policies

    DTIC Science & Technology

    2017-03-23

    Air Force Institute of Technology AFIT Scholar Theses and Dissertations 3-23-2017 Using Markov Decision Processes with Heterogeneous Queueing Systems... TECHNOLOGY Wright-Patterson Air Force Base, Ohio DISTRIBUTION STATEMENT A APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. The views expressed in...POLICIES THESIS Presented to the Faculty Department of Operational Sciences Graduate School of Engineering and Management Air Force Institute of Technology

  14. Predictive functional control for active queue management in congested TCP/IP networks.

    PubMed

    Bigdeli, N; Haeri, M

    2009-01-01

    Predictive functional control (PFC) as a new active queue management (AQM) method in dynamic TCP networks supporting explicit congestion notification (ECN) is proposed. The ability of the controller in handling system delay along with its simplicity and low computational load makes PFC a privileged AQM method in the high speed networks. Besides, considering the disturbance term (which represents model/process mismatches, external disturbances, and existing noise) in the control formulation adds some level of robustness into the PFC-AQM controller. This is an important and desired property in the control of dynamically-varying computer networks. In this paper, the controller is designed based on a small signal linearized fluid-flow model of the TCP/AQM networks. Then, closed-loop transfer function representation of the system is derived to analyze the robustness with respect to the network and controller parameters. The analytical as well as the packet-level ns-2 simulation results show the out-performance of the developed controller for both queue regulation and resource utilization. Fast response, low queue fluctuations (and consequently low delay jitter), high link utilization, good disturbance rejection, scalability, and low packet marking probability are other features of the developed method with respect to other well-known AQM methods such as RED, PI, and REM which are also simulated for comparison.

  15. Priority Queue Based Reactive Buffer Management Policy for Delay Tolerant Network under City Based Environments.

    PubMed

    Ayub, Qaisar; Ngadi, Asri; Rashid, Sulma; Habib, Hafiz Adnan

    2018-01-01

    Delay Tolerant Network (DTN) multi-copy routing protocols are privileged to create and transmit multiple copies of each message that causes congestion and some messages are dropped. This process is known as reactive drop because messages were dropped re-actively to overcome buffer overflows. The existing reactive buffer management policies apply a single metric to drop source, relay and destine messages. Hereby, selection to drop a message is dubious because each message as source, relay or destine may have consumed dissimilar magnitude of network resources. Similarly, DTN has included time to live (ttl) parameter which defines lifetime of message. Hence, when ttl expires then message is automatically destroyed from relay nodes. However, time-to-live (ttl) is not applicable on messages reached at their destinations. Moreover, nodes keep replicating messages till ttl expires even-though large number of messages has already been dispersed. In this paper, we have proposed Priority Queue Based Reactive Buffer Management Policy (PQB-R) for DTN under City Based Environments. The PQB-R classifies buffered messages into source, relay and destine queues. Moreover, separate drop metric has been applied on individual queue. The experiment results prove that proposed PQB-R has reduced number of messages transmissions, message drop and increases delivery ratio.

  16. Priority Queue Based Reactive Buffer Management Policy for Delay Tolerant Network under City Based Environments

    PubMed Central

    Ngadi, Asri; Rashid, Sulma; Habib, Hafiz Adnan

    2018-01-01

    Delay Tolerant Network (DTN) multi-copy routing protocols are privileged to create and transmit multiple copies of each message that causes congestion and some messages are dropped. This process is known as reactive drop because messages were dropped re-actively to overcome buffer overflows. The existing reactive buffer management policies apply a single metric to drop source, relay and destine messages. Hereby, selection to drop a message is dubious because each message as source, relay or destine may have consumed dissimilar magnitude of network resources. Similarly, DTN has included time to live (ttl) parameter which defines lifetime of message. Hence, when ttl expires then message is automatically destroyed from relay nodes. However, time-to-live (ttl) is not applicable on messages reached at their destinations. Moreover, nodes keep replicating messages till ttl expires even-though large number of messages has already been dispersed. In this paper, we have proposed Priority Queue Based Reactive Buffer Management Policy (PQB-R) for DTN under City Based Environments. The PQB-R classifies buffered messages into source, relay and destine queues. Moreover, separate drop metric has been applied on individual queue. The experiment results prove that proposed PQB-R has reduced number of messages transmissions, message drop and increases delivery ratio. PMID:29438438

  17. A robust fractional-order PID controller design based on active queue management for TCP network

    NASA Astrophysics Data System (ADS)

    Hamidian, Hamideh; Beheshti, Mohammad T. H.

    2018-01-01

    In this paper, a robust fractional-order controller is designed to control the congestion in transmission control protocol (TCP) networks with time-varying parameters. Fractional controllers can increase the stability and robustness. Regardless of advantages of fractional controllers, they are still not common in congestion control in TCP networks. The network parameters are time-varying, so the robust stability is important in congestion controller design. Therefore, we focused on the robust controller design. The fractional PID controller is developed based on active queue management (AQM). D-partition technique is used. The most important property of designed controller is the robustness to the time-varying parameters of the TCP network. The vertex quasi-polynomials of the closed-loop characteristic equation are obtained, and the stability boundaries are calculated for each vertex quasi-polynomial. The intersection of all stability regions is insensitive to network parameter variations, and results in robust stability of TCP/AQM system. NS-2 simulations show that the proposed algorithm provides a stable queue length. Moreover, simulations show smaller oscillations of the queue length and less packet drop probability for FPID compared to PI and PID controllers. We can conclude from NS-2 simulations that the average packet loss probability variations are negligible when the network parameters change.

  18. A Simulation Study of Paced TCP

    NASA Technical Reports Server (NTRS)

    Kulik, Joanna; Coulter, Robert; Rockwell, Dennis; Partridge, Craig

    2000-01-01

    In this paper, we study the performance of paced TCP, a modified version of TCP designed especially for high delay- bandwidth networks. In typical networks, TCP optimizes its send-rate by transmitting increasingly large bursts, or windows, of packets, one burst per round-trip time, until it reaches a maximum window-size, which corresponds to the full capacity of the network. In a network with a high delay-bandwidth product, however, Transmission Control Protocol's (TCPs) maximum window-size may be larger than the queue size of the intermediate routers, and routers will begin to drop packets as soon as the windows become too large for the router queues. The TCP sender then concludes that the bottleneck capacity of the network has been reached, and it limits its send-rate accordingly. Partridge proposed paced TCP as a means of solving the problem of queueing bottlenecks. A sender using paced TCP would release packets in multiple, small bursts during a round-trip time in which ordinary TCP would release a single, large burst of packets. This approach allows the sender to increase its send-rate to the maximum window size without encountering queueing bottlenecks. This paper describes the performance of paced TCP in a simulated network and discusses implementation details that can affect the performance of paced TCP.

  19. On-board landmark navigation and attitude reference parallel processor system

    NASA Technical Reports Server (NTRS)

    Gilbert, L. E.; Mahajan, D. T.

    1978-01-01

    An approach to autonomous navigation and attitude reference for earth observing spacecraft is described along with the landmark identification technique based on a sequential similarity detection algorithm (SSDA). Laboratory experiments undertaken to determine if better than one pixel accuracy in registration can be achieved consistent with onboard processor timing and capacity constraints are included. The SSDA is implemented using a multi-microprocessor system including synchronization logic and chip library. The data is processed in parallel stages, effectively reducing the time to match the small known image within a larger image as seen by the onboard image system. Shared memory is incorporated in the system to help communicate intermediate results among microprocessors. The functions include finding mean values and summation of absolute differences over the image search area. The hardware is a low power, compact unit suitable to onboard application with the flexibility to provide for different parameters depending upon the environment.

  20. Description and Simulation of a Fast Packet Switch Architecture for Communication Satellites

    NASA Technical Reports Server (NTRS)

    Quintana, Jorge A.; Lizanich, Paul J.

    1995-01-01

    The NASA Lewis Research Center has been developing the architecture for a multichannel communications signal processing satellite (MCSPS) as part of a flexible, low-cost meshed-VSAT (very small aperture terminal) network. The MCSPS architecture is based on a multifrequency, time-division-multiple-access (MF-TDMA) uplink and a time-division multiplex (TDM) downlink. There are eight uplink MF-TDMA beams, and eight downlink TDM beams, with eight downlink dwells per beam. The information-switching processor, which decodes, stores, and transmits each packet of user data to the appropriate downlink dwell onboard the satellite, has been fully described by using VHSIC (Very High Speed Integrated-Circuit) Hardware Description Language (VHDL). This VHDL code, which was developed in-house to simulate the information switching processor, showed that the architecture is both feasible and viable. This paper describes a shared-memory-per-beam architecture, its VHDL implementation, and the simulation efforts.

  1. Computer-aided design/computer-aided manufacturing skull base drill.

    PubMed

    Couldwell, William T; MacDonald, Joel D; Thomas, Charles L; Hansen, Bradley C; Lapalikar, Aniruddha; Thakkar, Bharat; Balaji, Alagar K

    2017-05-01

    The authors have developed a simple device for computer-aided design/computer-aided manufacturing (CAD-CAM) that uses an image-guided system to define a cutting tool path that is shared with a surgical machining system for drilling bone. Information from 2D images (obtained via CT and MRI) is transmitted to a processor that produces a 3D image. The processor generates code defining an optimized cutting tool path, which is sent to a surgical machining system that can drill the desired portion of bone. This tool has applications for bone removal in both cranial and spine neurosurgical approaches. Such applications have the potential to reduce surgical time and associated complications such as infection or blood loss. The device enables rapid removal of bone within 1 mm of vital structures. The validity of such a machining tool is exemplified in the rapid (< 3 minutes machining time) and accurate removal of bone for transtemporal (for example, translabyrinthine) approaches.

  2. Efficient quantum walk on a quantum processor

    PubMed Central

    Qiang, Xiaogang; Loke, Thomas; Montanaro, Ashley; Aungskunsiri, Kanin; Zhou, Xiaoqi; O'Brien, Jeremy L.; Wang, Jingbo B.; Matthews, Jonathan C. F.

    2016-01-01

    The random walk formalism is used across a wide range of applications, from modelling share prices to predicting population genetics. Likewise, quantum walks have shown much potential as a framework for developing new quantum algorithms. Here we present explicit efficient quantum circuits for implementing continuous-time quantum walks on the circulant class of graphs. These circuits allow us to sample from the output probability distributions of quantum walks on circulant graphs efficiently. We also show that solving the same sampling problem for arbitrary circulant quantum circuits is intractable for a classical computer, assuming conjectures from computational complexity theory. This is a new link between continuous-time quantum walks and computational complexity theory and it indicates a family of tasks that could ultimately demonstrate quantum supremacy over classical computers. As a proof of principle, we experimentally implement the proposed quantum circuit on an example circulant graph using a two-qubit photonics quantum processor. PMID:27146471

  3. Automation of Data Traffic Control on DSM Architecture

    NASA Technical Reports Server (NTRS)

    Frumkin, Michael; Jin, Hao-Qiang; Yan, Jerry

    2001-01-01

    The design of distributed shared memory (DSM) computers liberates users from the duty to distribute data across processors and allows for the incremental development of parallel programs using, for example, OpenMP or Java threads. DSM architecture greatly simplifies the development of parallel programs having good performance on a few processors. However, to achieve a good program scalability on DSM computers requires that the user understand data flow in the application and use various techniques to avoid data traffic congestions. In this paper we discuss a number of such techniques, including data blocking, data placement, data transposition and page size control and evaluate their efficiency on the NAS (NASA Advanced Supercomputing) Parallel Benchmarks. We also present a tool which automates the detection of constructs causing data congestions in Fortran array oriented codes and advises the user on code transformations for improving data traffic in the application.

  4. Parallel programming with Easy Java Simulations

    NASA Astrophysics Data System (ADS)

    Esquembre, F.; Christian, W.; Belloni, M.

    2018-01-01

    Nearly all of today's processors are multicore, and ideally programming and algorithm development utilizing the entire processor should be introduced early in the computational physics curriculum. Parallel programming is often not introduced because it requires a new programming environment and uses constructs that are unfamiliar to many teachers. We describe how we decrease the barrier to parallel programming by using a java-based programming environment to treat problems in the usual undergraduate curriculum. We use the easy java simulations programming and authoring tool to create the program's graphical user interface together with objects based on those developed by Kaminsky [Building Parallel Programs (Course Technology, Boston, 2010)] to handle common parallel programming tasks. Shared-memory parallel implementations of physics problems, such as time evolution of the Schrödinger equation, are available as source code and as ready-to-run programs from the AAPT-ComPADRE digital library.

  5. An Evaluation of Architectural Platforms for Parallel Navier-Stokes Computations

    NASA Technical Reports Server (NTRS)

    Jayasimha, D. N.; Hayder, M. E.; Pillay, S. K.

    1996-01-01

    We study the computational, communication, and scalability characteristics of a computational fluid dynamics application, which solves the time accurate flow field of a jet using the compressible Navier-Stokes equations, on a variety of parallel architecture platforms. The platforms chosen for this study are a cluster of workstations (the LACE experimental testbed at NASA Lewis), a shared memory multiprocessor (the Cray YMP), and distributed memory multiprocessors with different topologies - the IBM SP and the Cray T3D. We investigate the impact of various networks connecting the cluster of workstations on the performance of the application and the overheads induced by popular message passing libraries used for parallelization. The work also highlights the importance of matching the memory bandwidth to the processor speed for good single processor performance. By studying the performance of an application on a variety of architectures, we are able to point out the strengths and weaknesses of each of the example computing platforms.

  6. Parallelizing Navier-Stokes Computations on a Variety of Architectural Platforms

    NASA Technical Reports Server (NTRS)

    Jayasimha, D. N.; Hayder, M. E.; Pillay, S. K.

    1997-01-01

    We study the computational, communication, and scalability characteristics of a Computational Fluid Dynamics application, which solves the time accurate flow field of a jet using the compressible Navier-Stokes equations, on a variety of parallel architectural platforms. The platforms chosen for this study are a cluster of workstations (the LACE experimental testbed at NASA Lewis), a shared memory multiprocessor (the Cray YMP), distributed memory multiprocessors with different topologies-the IBM SP and the Cray T3D. We investigate the impact of various networks, connecting the cluster of workstations, on the performance of the application and the overheads induced by popular message passing libraries used for parallelization. The work also highlights the importance of matching the memory bandwidth to the processor speed for good single processor performance. By studying the performance of an application on a variety of architectures, we are able to point out the strengths and weaknesses of each of the example computing platforms.

  7. FOSS GIS on the GFZ HPC cluster: Towards a service-oriented Scientific Geocomputation Environment

    NASA Astrophysics Data System (ADS)

    Loewe, P.; Klump, J.; Thaler, J.

    2012-12-01

    High performance compute clusters can be used as geocomputation workbenches. Their wealth of resources enables us to take on geocomputation tasks which exceed the limitations of smaller systems. These general capabilities can be harnessed via tools such as Geographic Information System (GIS), provided they are able to utilize the available cluster configuration/architecture and provide a sufficient degree of user friendliness to allow for wide application. While server-level computing is clearly not sufficient for the growing numbers of data- or computation-intense tasks undertaken, these tasks do not get even close to the requirements needed for access to "top shelf" national cluster facilities. So until recently such kind of geocomputation research was effectively barred due to lack access to of adequate resources. In this paper we report on the experiences gained by providing GRASS GIS as a software service on a HPC compute cluster at the German Research Centre for Geosciences using Platform Computing's Load Sharing Facility (LSF). GRASS GIS is the oldest and largest Free Open Source (FOSS) GIS project. During ramp up in 2011, multiple versions of GRASS GIS (v 6.4.2, 6.5 and 7.0) were installed on the HPC compute cluster, which currently consists of 234 nodes with 480 CPUs providing 3084 cores. Nineteen different processing queues with varying hardware capabilities and priorities are provided, allowing for fine-grained scheduling and load balancing. After successful initial testing, mechanisms were developed to deploy scripted geocomputation tasks onto dedicated processing queues. The mechanisms are based on earlier work by NETELER et al. (2008) and allow to use all 3084 cores for GRASS based geocomputation work. However, in practice applications are limited to fewer resources as assigned to their respective queue. Applications of the new GIS functionality comprise so far of hydrological analysis, remote sensing and the generation of maps of simulated tsunamis in the Mediterranean Sea for the Tsunami Atlas of the FP-7 TRIDEC Project (www.tridec-online.eu). This included the processing of complex problems, requiring significant amounts of processing time up to full 20 CPU days. This GRASS GIS-based service is provided as a research utility in the sense of "Software as a Service" (SaaS) and is a first step towards a GFZ corporate cloud service.

  8. Distributed simulation using a real-time shared memory network

    NASA Technical Reports Server (NTRS)

    Simon, Donald L.; Mattern, Duane L.; Wong, Edmond; Musgrave, Jeffrey L.

    1993-01-01

    The Advanced Control Technology Branch of the NASA Lewis Research Center performs research in the area of advanced digital controls for aeronautic and space propulsion systems. This work requires the real-time implementation of both control software and complex dynamical models of the propulsion system. We are implementing these systems in a distributed, multi-vendor computer environment. Therefore, a need exists for real-time communication and synchronization between the distributed multi-vendor computers. A shared memory network is a potential solution which offers several advantages over other real-time communication approaches. A candidate shared memory network was tested for basic performance. The shared memory network was then used to implement a distributed simulation of a ramjet engine. The accuracy and execution time of the distributed simulation was measured and compared to the performance of the non-partitioned simulation. The ease of partitioning the simulation, the minimal time required to develop for communication between the processors and the resulting execution time all indicate that the shared memory network is a real-time communication technique worthy of serious consideration.

  9. Identification of Air Force Emerging Technologies and Militarily Significant Emerging Technologies.

    DTIC Science & Technology

    1985-08-31

    taking an integrated approach to avionics and EU, the various sensors and receivers on the aircraft can time-share the use of common signal processors...functions mentioned above has required, in addition to a separate sensor or antenna, a totally independent electronics suite. Many of the advanced...Classification A3. IMAGING SENSOR AUTOPROCESSOR The Air Force has contracted with Rockwell International and Honeywell in this work. Rockwell’s work is

  10. Cooperative system and method using mobile robots for testing a cooperative search controller

    DOEpatents

    Byrne, Raymond H.; Harrington, John J.; Eskridge, Steven E.; Hurtado, John E.

    2002-01-01

    A test system for testing a controller provides a way to use large numbers of miniature mobile robots to test a cooperative search controller in a test area, where each mobile robot has a sensor, a communication device, a processor, and a memory. A method of using a test system provides a way for testing a cooperative search controller using multiple robots sharing information and communicating over a communication network.

  11. Empirical synchronized flow in oversaturated city traffic.

    PubMed

    Kerner, Boris S; Hemmerle, Peter; Koller, Micha; Hermanns, Gerhard; Klenov, Sergey L; Rehborn, Hubert; Schreckenberg, Michael

    2014-09-01

    Based on a study of anonymized GPS probe vehicle traces measured by personal navigation devices in vehicles randomly distributed in city traffic, empirical synchronized flow in oversaturated city traffic has been revealed. It turns out that real oversaturated city traffic resulting from speed breakdown in a city in most cases can be considered random spatiotemporal alternations between sequences of moving queues and synchronized flow patterns in which the moving queues do not occur.

  12. Sample Batch Scripts for Running Jobs on the Peregrine System |

    Science.gov Websites

    script for a serial job in the debug queue #!/bin/bash #PBS -lnodes=1:ppn=1,walltime=500 #PBS -N test1 limit #PBS -l nodes=1 # one node #PBS -N test1 # Name of job #PBS -A CSC001 # project handle cd #PBS -q short # short queue #PBS -l nodes=4:ppn=24 # Number of nodes, put 24 processes on each #PBS -N

  13. Analysis on preemptive priority retrial queue with two types of customers, balking, optional re-service, single vacation and service interruption

    NASA Astrophysics Data System (ADS)

    Yuvarani, S.; Saravanarajan, M. C.

    2017-11-01

    This paper concerned with performance analysis of single server preemptive priority retrial queue with a single vacation where two types of customers are considered and they are called priority customers and ordinary customers. The ordinary customers arrive in batch into the system. The priority customers do not form any queue. After the completion of regular service, the customers may demand re-service for the previous service without joining the orbit or may leave the system. As soon as the system is empty, the server goes for vacation and the regular busy server can be subjected to breakdown. By using the supplementary variable technique, we obtain the steady-state probability generating functions for the system/orbit size. Some important system performance measures and the stochastic decomposition are discussed. Finally, numerical examples are presented to visualize the effect of parameters on system performance measures.

  14. Counter design influences the privacy of patients in health care.

    PubMed

    Mobach, Mark P

    2009-03-01

    A re-furnishing of counter areas in primary health care was used to assess patient privacy and its influences on the nature of conversations in a controlled experiment. Patients in two community-based pharmacies in the Netherlands were assigned to enclosed counters and a queue at distance, or to counters that exposed patients mutually and a closer queue. Patients assigned to counters with reduced sight were more satisfied with the privacy than patients at visually exposed counters. However, in comparison with visually exposed pharmacy counters, conversations of patients at enclosed counters could still be overheard and did not have different conversations to other patients. Architectural design of health-care institutions has potential to positively influence perceived patient privacy in areas in where multiple patient-staff communications routinely occur and where patient privacy is an important issue, but enclosed counters with a queue at distance do not prevent incidental disclosure of individually identifiable health information.

  15. Managing patients' wait time in specialist out-patient clinic using real-time data from existing queue management and ADT systems.

    PubMed

    Ju, John Chen; Gan, Soon Ann; Tan Siew Wee, Justine; Huang Yuchi, Peter; Mei Mei, Chan; Wong Mei Mei, Sharon; Fong, Kam Weng

    2013-01-01

    In major cancer centers, heavy patients load and multiple registration stations could cause significant wait time, and can be result in patient complains. Real-time patient journey data and visual display are useful tools in hospital patient queue management. This paper demonstrates how we capture patient queue data without deploying any tracing devices; and how to convert data into useful patient journey information to understand where interventions are likely to be most effective. During our system development, remarkable effort has been spent on resolving data discrepancy and balancing between accuracy and system performances. A web-based dashboard to display real-time information and a framework for data analysis were also developed to facilitate our clinics' operation. Result shows our system could eliminate more than 95% of data capturing errors and has improved patient wait time data accuracy since it was deployed.

  16. The queueing perspective of asynchronous network coding in two-way relay network

    NASA Astrophysics Data System (ADS)

    Liang, Yaping; Chang, Qing; Li, Xianxu

    2018-04-01

    Asynchronous network coding (NC) has potential to improve the wireless network performance compared with a routing or the synchronous network coding. Recent researches concentrate on the optimization between throughput/energy consuming and delay with a couple of independent input flow. However, the implementation of NC requires a thorough investigation of its impact on relevant queueing systems where few work focuses on. Moreover, few works study the probability density function (pdf) in network coding scenario. In this paper, the scenario with two independent Poisson input flows and one output flow is considered. The asynchronous NC-based strategy is that a new arrival evicts a head packet holding in its queue when waiting for another packet from the other flow to encode. The pdf for the output flow which contains both coded and uncoded packets is derived. Besides, the statistic characteristics of this strategy are analyzed. These results are verified by numerical simulations.

  17. On buffer overflow duration in a finite-capacity queueing system with multiple vacation policy

    NASA Astrophysics Data System (ADS)

    Kempa, Wojciech M.

    2017-12-01

    A finite-buffer queueing system with Poisson arrivals and generally distributed processing times, operating under multiple vacation policy, is considered. Each time when the system becomes empty, the service station takes successive independent and identically distributed vacation periods, until, at the completion epoch of one of them, at least one job waiting for service is detected in the buffer. Applying analytical approach based on the idea of embedded Markov chain, integral equations and linear algebra, the compact-form representation for the cumulative distribution function (CDF for short) of the first buffer overflow duration is found. Hence, the formula for the CDF of next such periods is obtained. Moreover, probability distributions of the number of job losses in successive buffer overflow periods are found. The considered queueing system can be efficienly applied in modelling energy saving mechanisms in wireless network communication.

  18. Conservative parallel simulation of priority class queueing networks

    NASA Technical Reports Server (NTRS)

    Nicol, David

    1992-01-01

    A conservative synchronization protocol is described for the parallel simulation of queueing networks having C job priority classes, where a job's class is fixed. This problem has long vexed designers of conservative synchronization protocols because of its seemingly poor ability to compute lookahead: the time of the next departure. For, a job in service having low priority can be preempted at any time by an arrival having higher priority and an arbitrarily small service time. The solution is to skew the event generation activity so that the events for higher priority jobs are generated farther ahead in simulated time than lower priority jobs. Thus, when a lower priority job enters service for the first time, all the higher priority jobs that may preempt it are already known and the job's departure time can be exactly predicted. Finally, the protocol was analyzed and it was demonstrated that good performance can be expected on the simulation of large queueing networks.

  19. Conservative parallel simulation of priority class queueing networks

    NASA Technical Reports Server (NTRS)

    Nicol, David M.

    1990-01-01

    A conservative synchronization protocol is described for the parallel simulation of queueing networks having C job priority classes, where a job's class is fixed. This problem has long vexed designers of conservative synchronization protocols because of its seemingly poor ability to compute lookahead: the time of the next departure. For, a job in service having low priority can be preempted at any time by an arrival having higher priority and an arbitrarily small service time. The solution is to skew the event generation activity so that the events for higher priority jobs are generated farther ahead in simulated time than lower priority jobs. Thus, when a lower priority job enters service for the first time, all the higher priority jobs that may preempt it are already known and the job's departure time can be exactly predicted. Finally, the protocol was analyzed and it was demonstrated that good performance can be expected on the simulation of large queueing networks.

  20. Parallel computing for probabilistic fatigue analysis

    NASA Technical Reports Server (NTRS)

    Sues, Robert H.; Lua, Yuan J.; Smith, Mark D.

    1993-01-01

    This paper presents the results of Phase I research to investigate the most effective parallel processing software strategies and hardware configurations for probabilistic structural analysis. We investigate the efficiency of both shared and distributed-memory architectures via a probabilistic fatigue life analysis problem. We also present a parallel programming approach, the virtual shared-memory paradigm, that is applicable across both types of hardware. Using this approach, problems can be solved on a variety of parallel configurations, including networks of single or multiprocessor workstations. We conclude that it is possible to effectively parallelize probabilistic fatigue analysis codes; however, special strategies will be needed to achieve large-scale parallelism to keep large number of processors busy and to treat problems with the large memory requirements encountered in practice. We also conclude that distributed-memory architecture is preferable to shared-memory for achieving large scale parallelism; however, in the future, the currently emerging hybrid-memory architectures will likely be optimal.

  1. Parallelization of KENO-Va Monte Carlo code

    NASA Astrophysics Data System (ADS)

    Ramón, Javier; Peña, Jorge

    1995-07-01

    KENO-Va is a code integrated within the SCALE system developed by Oak Ridge that solves the transport equation through the Monte Carlo Method. It is being used at the Consejo de Seguridad Nuclear (CSN) to perform criticality calculations for fuel storage pools and shipping casks. Two parallel versions of the code: one for shared memory machines and other for distributed memory systems using the message-passing interface PVM have been generated. In both versions the neutrons of each generation are tracked in parallel. In order to preserve the reproducibility of the results in both versions, advanced seeds for random numbers were used. The CONVEX C3440 with four processors and shared memory at CSN was used to implement the shared memory version. A FDDI network of 6 HP9000/735 was employed to implement the message-passing version using proprietary PVM. The speedup obtained was 3.6 in both cases.

  2. Optimization of image processing algorithms on mobile platforms

    NASA Astrophysics Data System (ADS)

    Poudel, Pramod; Shirvaikar, Mukul

    2011-03-01

    This work presents a technique to optimize popular image processing algorithms on mobile platforms such as cell phones, net-books and personal digital assistants (PDAs). The increasing demand for video applications like context-aware computing on mobile embedded systems requires the use of computationally intensive image processing algorithms. The system engineer has a mandate to optimize them so as to meet real-time deadlines. A methodology to take advantage of the asymmetric dual-core processor, which includes an ARM and a DSP core supported by shared memory, is presented with implementation details. The target platform chosen is the popular OMAP 3530 processor for embedded media systems. It has an asymmetric dual-core architecture with an ARM Cortex-A8 and a TMS320C64x Digital Signal Processor (DSP). The development platform was the BeagleBoard with 256 MB of NAND RAM and 256 MB SDRAM memory. The basic image correlation algorithm is chosen for benchmarking as it finds widespread application for various template matching tasks such as face-recognition. The basic algorithm prototypes conform to OpenCV, a popular computer vision library. OpenCV algorithms can be easily ported to the ARM core which runs a popular operating system such as Linux or Windows CE. However, the DSP is architecturally more efficient at handling DFT algorithms. The algorithms are tested on a variety of images and performance results are presented measuring the speedup obtained due to dual-core implementation. A major advantage of this approach is that it allows the ARM processor to perform important real-time tasks, while the DSP addresses performance-hungry algorithms.

  3. Spaceborne Processor Array

    NASA Technical Reports Server (NTRS)

    Chow, Edward T.; Schatzel, Donald V.; Whitaker, William D.; Sterling, Thomas

    2008-01-01

    A Spaceborne Processor Array in Multifunctional Structure (SPAMS) can lower the total mass of the electronic and structural overhead of spacecraft, resulting in reduced launch costs, while increasing the science return through dynamic onboard computing. SPAMS integrates the multifunctional structure (MFS) and the Gilgamesh Memory, Intelligence, and Network Device (MIND) multi-core in-memory computer architecture into a single-system super-architecture. This transforms every inch of a spacecraft into a sharable, interconnected, smart computing element to increase computing performance while simultaneously reducing mass. The MIND in-memory architecture provides a foundation for high-performance, low-power, and fault-tolerant computing. The MIND chip has an internal structure that includes memory, processing, and communication functionality. The Gilgamesh is a scalable system comprising multiple MIND chips interconnected to operate as a single, tightly coupled, parallel computer. The array of MIND components shares a global, virtual name space for program variables and tasks that are allocated at run time to the distributed physical memory and processing resources. Individual processor- memory nodes can be activated or powered down at run time to provide active power management and to configure around faults. A SPAMS system is comprised of a distributed Gilgamesh array built into MFS, interfaces into instrument and communication subsystems, a mass storage interface, and a radiation-hardened flight computer.

  4. Comparison of Origin 2000 and Origin 3000 Using NAS Parallel Benchmarks

    NASA Technical Reports Server (NTRS)

    Turney, Raymond D.

    2001-01-01

    This report describes results of benchmark tests on the Origin 3000 system currently being installed at the NASA Ames National Advanced Supercomputing facility. This machine will ultimately contain 1024 R14K processors. The first part of the system, installed in November, 2000 and named mendel, is an Origin 3000 with 128 R12K processors. For comparison purposes, the tests were also run on lomax, an Origin 2000 with R12K processors. The BT, LU, and SP application benchmarks in the NAS Parallel Benchmark Suite and the kernel benchmark FT were chosen to determine system performance and measure the impact of changes on the machine as it evolves. Having been written to measure performance on Computational Fluid Dynamics applications, these benchmarks are assumed appropriate to represent the NAS workload. Since the NAS runs both message passing (MPI) and shared-memory, compiler directive type codes, both MPI and OpenMP versions of the benchmarks were used. The MPI versions used were the latest official release of the NAS Parallel Benchmarks, version 2.3. The OpenMP versiqns used were PBN3b2, a beta version that is in the process of being released. NPB 2.3 and PBN 3b2 are technically different benchmarks, and NPB results are not directly comparable to PBN results.

  5. Benchmark tests on the digital equipment corporation Alpha AXP 21164-based AlphaServer 8400, including a comparison of optimized vector and superscalar processing

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wasserman, H.J.

    1996-02-01

    The second generation of the Digital Equipment Corp. (DEC) DECchip Alpha AXP microprocessor is referred to as the 21164. From the viewpoint of numerically-intensive computing, the primary difference between it and its predecessor, the 21064, is that the 21164 has twice the multiply/add throughput per clock period (CP), a maximum of two floating point operations (FLOPS) per CP vs. one for 21064. The AlphaServer 8400 is a shared-memory multiprocessor server system that can accommodate up to 12 CPUs and up to 14 GB of memory. In this report we will compare single processor performance of the 8400 system with thatmore » of the International Business Machines Corp. (IBM) RISC System/6000 POWER-2 microprocessor running at 66 MHz, the Silicon Graphics, Inc. (SGI) MIPS R8000 microprocessor running at 75 MHz, and the Cray Research, Inc. CRAY J90. The performance comparison is based on a set of Fortran benchmark codes that represent a portion of the Los Alamos National Laboratory supercomputer workload. The advantage of using these codes, is that the codes also span a wide range of computational characteristics, such as vectorizability, problem size, and memory access pattern. The primary disadvantage of using them is that detailed, quantitative analysis of performance behavior of all codes on all machines is difficult. One important addition to the benchmark set appears for the first time in this report. Whereas the older version was written for a vector processor, the newer version is more optimized for microprocessor architectures. Therefore, we have for the first time, an opportunity to measure performance on a single application using implementations that expose the respective strengths of vector and superscalar architecture. All results in this report are from single processors. A subsequent article will explore shared-memory multiprocessing performance of the 8400 system.« less

  6. Feasibility of through-time spiral generalized autocalibrating partial parallel acquisition for low latency accelerated real-time MRI of speech.

    PubMed

    Lingala, Sajan Goud; Zhu, Yinghua; Lim, Yongwan; Toutios, Asterios; Ji, Yunhua; Lo, Wei-Ching; Seiberlich, Nicole; Narayanan, Shrikanth; Nayak, Krishna S

    2017-12-01

    To evaluate the feasibility of through-time spiral generalized autocalibrating partial parallel acquisition (GRAPPA) for low-latency accelerated real-time MRI of speech. Through-time spiral GRAPPA (spiral GRAPPA), a fast linear reconstruction method, is applied to spiral (k-t) data acquired from an eight-channel custom upper-airway coil. Fully sampled data were retrospectively down-sampled to evaluate spiral GRAPPA at undersampling factors R = 2 to 6. Pseudo-golden-angle spiral acquisitions were used for prospective studies. Three subjects were imaged while performing a range of speech tasks that involved rapid articulator movements, including fluent speech and beat-boxing. Spiral GRAPPA was compared with view sharing, and a parallel imaging and compressed sensing (PI-CS) method. Spiral GRAPPA captured spatiotemporal dynamics of vocal tract articulators at undersampling factors ≤4. Spiral GRAPPA at 18 ms/frame and 2.4 mm 2 /pixel outperformed view sharing in depicting rapidly moving articulators. Spiral GRAPPA and PI-CS provided equivalent temporal fidelity. Reconstruction latency per frame was 14 ms for view sharing and 116 ms for spiral GRAPPA, using a single processor. Spiral GRAPPA kept up with the MRI data rate of 18ms/frame with eight processors. PI-CS required 17 minutes to reconstruct 5 seconds of dynamic data. Spiral GRAPPA enabled 4-fold accelerated real-time MRI of speech with a low reconstruction latency. This approach is applicable to wide range of speech RT-MRI experiments that benefit from real-time feedback while visualizing rapid articulator movement. Magn Reson Med 78:2275-2282, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  7. State dependent arrival in bulk retrial queueing system with immediate Bernoulli feedback, multiple vacations and threshold

    NASA Astrophysics Data System (ADS)

    Niranjan, S. P.; Chandrasekaran, V. M.; Indhira, K.

    2017-11-01

    The objective of this paper is to analyse state dependent arrival in bulk retrial queueing system with immediate Bernoulli feedback, multiple vacations, threshold and constant retrial policy. Primary customers are arriving into the system in bulk with different arrival rates λ a and λ b . If arriving customers find the server is busy then the entire batch will join to orbit. Customer from orbit request service one by one with constant retrial rate γ. On the other hand if an arrival of customers finds the server is idle then customers will be served in batches according to general bulk service rule. After service completion, customers may request service again with probability δ as feedback or leave from the system with probability 1 - δ. In the service completion epoch, if the orbit size is zero then the server leaves for multiple vacations. The server continues the vacation until the orbit size reaches the value ‘N’ (N > b). At the vacation completion, if the orbit size is ‘N’ then the server becomes ready to provide service for customers from the main pool or from the orbit. For the designed queueing model, probability generating function of the queue size at an arbitrary time will be obtained by using supplementary variable technique. Various performance measures will be derived with suitable numerical illustrations.

  8. Proteolytic crosstalk in multi-protease networks

    NASA Astrophysics Data System (ADS)

    Ogle, Curtis T.; Mather, William H.

    2016-04-01

    Processive proteases, such as ClpXP in E. coli, are conserved enzyme assemblies that can recognize and rapidly degrade proteins. These proteases are used for a number of purposes, including degrading mistranslated proteins and controlling cellular stress response. However, proteolytic machinery within the cell is limited in capacity and can lead to a bottleneck in protein degradation, whereby many proteins compete (‘queue’) for proteolytic resources. Previous work has demonstrated that such queueing can lead to pronounced statistical relationships between different protein counts when proteins compete for a single common protease. However, real cells contain many different proteases, e.g. ClpXP, ClpAP, and Lon in E. coli, and it is not clear how competition between proteins for multiple classes of protease would influence the dynamics of cellular networks. In the present work, we theoretically demonstrate that a multi-protease proteolytic bottleneck can substantially couple the dynamics for both simple and complex (oscillatory) networks, even between substrates with substantially different affinities for protease. For these networks, queueing often leads to strong positive correlations between protein counts, and these correlations are strongest near the queueing theoretic point of balance. Furthermore, we find that the qualitative behavior of these networks depends on the relative size of the absolute affinity of substrate to protease compared to the cross affinity of substrate to protease, leading in certain regimes to priority queue statistics.

  9. Software-Controlled Caches in the VMP Multiprocessor

    DTIC Science & Technology

    1986-03-01

    programming system level that Processors is tuned for the VMP design. In this vein, we are interested in exploring how far the software support can go to ...handled in software, analogously to the handling agement of the shared program state is familiar and of virtual memory page faults. Hardware support for...ensure good behavior, as opposed to how Each cache miss results in bus traffic. Table 2 pro- vides the bus cost for the "average" cache miss. Fig

  10. Thread Migration in the Presence of Pointers

    NASA Technical Reports Server (NTRS)

    Cronk, David; Haines, Matthew; Mehrotra, Piyush

    1996-01-01

    Dynamic migration of lightweight threads supports both data locality and load balancing. However, migrating threads that contain pointers referencing data in both the stack and heap remains an open problem. In this paper we describe a technique by which threads with pointers referencing both stack and non-shared heap data can be migrated such that the pointers remain valid after migration. As a result, threads containing pointers can now be migrated between processors in a homogeneous distributed memory environment.

  11. The Mark III Hypercube-Ensemble Computers

    NASA Technical Reports Server (NTRS)

    Peterson, John C.; Tuazon, Jesus O.; Lieberman, Don; Pniel, Moshe

    1988-01-01

    Mark III Hypercube concept applied in development of series of increasingly powerful computers. Processor of each node of Mark III Hypercube ensemble is specialized computer containing three subprocessors and shared main memory. Solves problem quickly by simultaneously processing part of problem at each such node and passing combined results to host computer. Disciplines benefitting from speed and memory capacity include astrophysics, geophysics, chemistry, weather, high-energy physics, applied mechanics, image processing, oil exploration, aircraft design, and microcircuit design.

  12. The force on the flex: Global parallelism and portability

    NASA Technical Reports Server (NTRS)

    Jordan, H. F.

    1986-01-01

    A parallel programming methodology, called the force, supports the construction of programs to be executed in parallel by an unspecified, but potentially large, number of processes. The methodology was originally developed on a pipelined, shared memory multiprocessor, the Denelcor HEP, and embodies the primitive operations of the force in a set of macros which expand into multiprocessor Fortran code. A small set of primitives is sufficient to write large parallel programs, and the system has been used to produce 10,000 line programs in computational fluid dynamics. The level of complexity of the force primitives is intermediate. It is high enough to mask detailed architectural differences between multiprocessors but low enough to give the user control over performance. The system is being ported to a medium scale multiprocessor, the Flex/32, which is a 20 processor system with a mixture of shared and local memory. Memory organization and the type of processor synchronization supported by the hardware on the two machines lead to some differences in efficient implementations of the force primitives, but the user interface remains the same. An initial implementation was done by retargeting the macros to Flexible Computer Corporation's ConCurrent C language. Subsequently, the macros were caused to directly produce the system calls which form the basis for ConCurrent C. The implementation of the Fortran based system is in step with Flexible Computer Corporations's implementation of a Fortran system in the parallel environment.

  13. Implementing Shared Memory Parallelism in MCBEND

    NASA Astrophysics Data System (ADS)

    Bird, Adam; Long, David; Dobson, Geoff

    2017-09-01

    MCBEND is a general purpose radiation transport Monte Carlo code from AMEC Foster Wheelers's ANSWERS® Software Service. MCBEND is well established in the UK shielding community for radiation shielding and dosimetry assessments. The existing MCBEND parallel capability effectively involves running the same calculation on many processors. This works very well except when the memory requirements of a model restrict the number of instances of a calculation that will fit on a machine. To more effectively utilise parallel hardware OpenMP has been used to implement shared memory parallelism in MCBEND. This paper describes the reasoning behind the choice of OpenMP, notes some of the challenges of multi-threading an established code such as MCBEND and assesses the performance of the parallel method implemented in MCBEND.

  14. Rapid solution of large-scale systems of equations

    NASA Technical Reports Server (NTRS)

    Storaasli, Olaf O.

    1994-01-01

    The analysis and design of complex aerospace structures requires the rapid solution of large systems of linear and nonlinear equations, eigenvalue extraction for buckling, vibration and flutter modes, structural optimization and design sensitivity calculation. Computers with multiple processors and vector capabilities can offer substantial computational advantages over traditional scalar computer for these analyses. These computers fall into two categories: shared memory computers and distributed memory computers. This presentation covers general-purpose, highly efficient algorithms for generation/assembly or element matrices, solution of systems of linear and nonlinear equations, eigenvalue and design sensitivity analysis and optimization. All algorithms are coded in FORTRAN for shared memory computers and many are adapted to distributed memory computers. The capability and numerical performance of these algorithms will be addressed.

  15. Dynamic programming on a shared-memory multiprocessor

    NASA Technical Reports Server (NTRS)

    Edmonds, Phil; Chu, Eleanor; George, Alan

    1993-01-01

    Three new algorithms for solving dynamic programming problems on a shared-memory parallel computer are described. All three algorithms attempt to balance work load, while keeping synchronization cost low. In particular, for a multiprocessor having p processors, an analysis of the best algorithm shows that the arithmetic cost is O(n-cubed/6p) and that the synchronization cost is O(absolute value of log sub C n) if p much less than n, where C = (2p-1)/(2p + 1) and n is the size of the problem. The low synchronization cost is important for machines where synchronization is expensive. Analysis and experiments show that the best algorithm is effective in balancing the work load and producing high efficiency.

  16. NPS and the methadone queue: Spillages of space and time.

    PubMed

    Alexandrescu, Liviu

    2017-02-01

    Between 2008 and 2013, powder-stimulants sold by 'head shops' as novel psychoactive substances (NPS) or 'legal highs' have displaced heroin among groups of injecting substance users in Bucharest, Romania. Rising HIV-infection rates and other medical or social harms have been reported to follow this trend. The study builds on two sets of original (N=30) and existing (N=20) interview data and on observations collected mainly at the site of a methadone substitution treatment facility. By disentangling the space-time continuum of the methadone queue, this paper argues that injecting drug users' (IDUs) passage from opiates to amphetamine-type stimulants (ATS) can be understood as 'spillages' of space and time. IDUs thus 'spill' out of the disciplinary flows of methadone treatment in two ways. The first is that of space and materiality. Drawing on actor-network theory (ANT), ATS/NPS appear embedded in reconfigured practices and rituals of injecting use. Such spillages see the pleasure-seeking self being fluidised in forming connections with, or spilling into, nonhuman actants such as substances, settings or objects. The second dimension of spilling is that of time. In this sense, heroin use is a 'cryogenic strategy' of inhabiting history and facing the transition to the market society that Romanian opiate injectors spill out of, not able to appropriate choice and legitimate consumption. The phenomenological qualities of stimulants that seem to accelerate lived time and generalise desire thus present them with an opportunity to alleviate a form of what a post-communist moral imaginary of transition frames as debilitating nostalgia. ATS/NPS are revealed as fluid entities that do not only shape risk conditions but also alter shared meanings and contextual configurations of bodies, substances and disciplinary regimes in unpredictable ways. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. General software design for multisensor data fusion

    NASA Astrophysics Data System (ADS)

    Zhang, Junliang; Zhao, Yuming

    1999-03-01

    In this paper a general method of software design for multisensor data fusion is discussed in detail, which adopts object-oriented technology under UNIX operation system. The software for multisensor data fusion is divided into six functional modules: data collection, database management, GIS, target display and alarming data simulation etc. Furthermore, the primary function, the components and some realization methods of each modular is given. The interfaces among these functional modular relations are discussed. The data exchange among each functional modular is performed by interprocess communication IPC, including message queue, semaphore and shared memory. Thus, each functional modular is executed independently, which reduces the dependence among functional modules and helps software programing and testing. This software for multisensor data fusion is designed as hierarchical structure by the inheritance character of classes. Each functional modular is abstracted and encapsulated through class structure, which avoids software redundancy and enhances readability.

  18. Delay decomposition at a single server queue with constant service time and multiple inputs

    NASA Technical Reports Server (NTRS)

    Ziegler, C.; Schilling, D. L.

    1978-01-01

    Two network consisting of single server queues, each with a constant service time, are considered. The external inputs to each network are assumed to follow some general probability distribution. Several interesting equivalencies that exist between the two networks considered are derived. This leads to the introduction of an important concept in delay decomposition. It is shown that the waiting time experienced by a customer can be decomposed into two basic components called self-delay and interference delay.

  19. C3 EVAL Model Development and Test. Volume 2. Programmers Manual.

    DTIC Science & Technology

    1985-10-01

    requests for CAS (message types 2900, 3000, 3400) and has a non- 61 - ~~.t -o-5. Sd% NODE MESSAGE DEST DEST PLINK LINKI ALT1 LINK2 ALT2 . LINKP • LINKA1...LINKA2 LINKn ALTi PLINK LINKI LINK2 LINKn ALT2 PLINK LINKI LINK2 * LINKn Figure 13: PARAMETERS IN COMMUNICATIONS ALLOCATION null pointer to its...SUBROUTINE HOLDQ1 (IPASS) * MOVE PRIORITY MESSAGES FROM HOLD QUEUE TO ALTERNATE * COMMUNICATIONS LINKI SEND QUEUE * CALLS - SNAP, FIND

  20. Efficient Distribution of Triggered Synchronous Block Diagrams

    DTIC Science & Technology

    2011-10-21

    corresponding FFP processes, from P to P ′. The sizes of the queues are as in [23]. In particular, if M is not Moore, a queue of size 1 suffices; ifM is Moore...computer systems. Real-Time Systems, 14(3):219–250, 1998. [23] S . Tripakis, C. Pinello, A . Benveniste, A . Sangiovanni-Vincent, P. Caspi, and M . Di...of connections: a data connection connects some output port of a block M to some input port of another block M ′; a trigger connection connects some

  1. Ada Quality and Style: Guidelines for Professional Programmers

    DTIC Science & Technology

    1991-01-01

    occured because entry queues are serviced in FIFO order, not by priority. There is another situation referred to as a race condition. A program like the...the value of ’COUNT. A task can be removed from an entry queue due to execution of an abort statement as well as expiration of a timed entry call. The...is not defined by the language and may vary from time sliced to preemptive priority. Some implementations (e.g., VAX Ada) provide several choices

  2. Ammunition Resupply Model. Volume II. Programmers Manual.

    DTIC Science & Technology

    1980-03-01

    pointer tables. If the placement is successful the flag ( ICHECK ) is set equal to 1. COMMON BLOCKS: EVENTS CALLS: NONE IS CALLED BY: SCHED CALLING PARAMETERS...decimal portion of the event time multiplied by 3600. ICHECK - 0 if no room on the file, I if there is room on the file. LOCAL ARRAYS: JFORE (1024...8217EVT, ITH, I-IS, !CHECK) C PUTEVT PLACES AN EVENT RECORD IN -THE QUEUE IN CHRONOLOGICAL C ORDER A,1D UPDATES THE QUEUE DIRECTORY. ICHECK FLAG SET C IF

  3. An application of queueing theory to the design of channel requirements for special purpose communications satellites. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Hein, G. F.

    1974-01-01

    Special purpose satellites are very cost sensitive to the number of broadcast channels, usually will have Poisson arrivals, fairly low utilization (less than 35%), and a very high availability requirement. To solve the problem of determining the effects of limiting C the number of channels, the Poisson arrival, infinite server queueing model will be modified to describe the many server case. The model is predicated on the reproductive property of the Poisson distribution.

  4. Queueing Network Models for Parallel Processing of Task Systems: an Operational Approach

    NASA Technical Reports Server (NTRS)

    Mak, Victor W. K.

    1986-01-01

    Computer performance modeling of possibly complex computations running on highly concurrent systems is considered. Earlier works in this area either dealt with a very simple program structure or resulted in methods with exponential complexity. An efficient procedure is developed to compute the performance measures for series-parallel-reducible task systems using queueing network models. The procedure is based on the concept of hierarchical decomposition and a new operational approach. Numerical results for three test cases are presented and compared to those of simulations.

  5. Automated Euler and Navier-Stokes Database Generation for a Glide-Back Booster

    NASA Technical Reports Server (NTRS)

    Chaderjian, Neal M.; Rogers, Stuart E.; Aftosmis, Mike J.; Pandya, Shishir A.; Ahmad, Jasim U.; Tejnil, Edward

    2004-01-01

    The past two decades have seen a sustained increase in the use of high fidelity Computational Fluid Dynamics (CFD) in basic research, aircraft design, and the analysis of post-design issues. As the fidelity of a CFD method increases, the number of cases that can be readily and affordably computed greatly diminishes. However, computer speeds now exceed 2 GHz, hundreds of processors are currently available and more affordable, and advances in parallel CFD algorithms scale more readily with large numbers of processors. All of these factors make it feasible to compute thousands of high fidelity cases. However, there still remains the overwhelming task of monitoring the solution process. This paper presents an approach to automate the CFD solution process. A new software tool, AeroDB, is used to compute thousands of Euler and Navier-Stokes solutions for a 2nd generation glide-back booster in one week. The solution process exploits a common job-submission grid environment, the NASA Information Power Grid (IPG), using 13 computers located at 4 different geographical sites. Process automation and web-based access to a MySql database greatly reduces the user workload, removing much of the tedium and tendency for user input errors. The AeroDB framework is shown. The user submits/deletes jobs, monitors AeroDB's progress, and retrieves data and plots via a web portal. Once a job is in the database, a job launcher uses an IPG resource broker to decide which computers are best suited to run the job. Job/code requirements, the number of CPUs free on a remote system, and queue lengths are some of the parameters the broker takes into account. The Globus software provides secure services for user authentication, remote shell execution, and secure file transfers over an open network. AeroDB automatically decides when a job is completed. Currently, the Cart3D unstructured flow solver is used for the Euler equations, and the Overflow structured overset flow solver is used for the Navier-Stokes equations. Other codes can be readily included into the AeroDB framework.

  6. Performance Evaluation of a M/Geo[xy]/1 Queue with varying probabilities of success which Treats Two Like Jobs As a Single Entity

    NASA Astrophysics Data System (ADS)

    Gowrishankar, Lavanya; Bhaskar, Vidhyacharan; Sundarammal, K.

    2018-04-01

    The developed model comprises of a single server capable of handling two different job types X and Y type job. Job Y takes more time for execution than job X. The objective is to construct a single server which would replace the standard M/M/2 queuing model The method used to find the relative measures involves the cost equation. The properties of the service distribution are discussed in detail. The maximum likelihood estimates for the parameters are obtained. The results are analytically derived for the M/Geo[xy]/1 model. A comparison is done between the model proposed and the standard M/M/2 queue. From the numerical results, it is observed that the waiting time in queue increases as the number of cycles is increased but however it is more economical than the M/M/2 model with restriction on the number of time slices.

  7. The Queued Service Observing Project at CFHT

    NASA Astrophysics Data System (ADS)

    Martin, Pierre; Savalle, Renaud; Vermeulen, Tom; Shapiro, Joshua N.

    2002-12-01

    In order to maximize the scientific productivity of the CFH12K mosaic wide-field imager (and soon MegaCam), the Queued Service Observing (QSO) mode was implemented at the Canada-France-Hawaii Telescope at the beginning of 2001. The QSO system consists of an ensemble of software components allowing for the submission of programs, the preparation of queues, and finally the execution and evaluation of observations. The QSO project is part of a broader system known as the New Observing Process (NOP). This system includes data acquisition, data reduction and analysis through a pipeline named Elixir, and a data archiving and distribution component (DADS). In this paper, we review several technical and operational aspects of the QSO project. In particular, we present our strategy, technical architecture, program submission system, and the tools developed for the preparation and execution of the queues. Our successful experience of over 150 nights of QSO operations is also discussed along with the future plans for queue observing with MegaCam and other instruments at CFHT.

  8. Design of a real-time wind turbine simulator using a custom parallel architecture

    NASA Technical Reports Server (NTRS)

    Hoffman, John A.; Gluck, R.; Sridhar, S.

    1995-01-01

    The design of a new parallel-processing digital simulator is described. The new simulator has been developed specifically for analysis of wind energy systems in real time. The new processor has been named: the Wind Energy System Time-domain simulator, version 3 (WEST-3). Like previous WEST versions, WEST-3 performs many computations in parallel. The modules in WEST-3 are pure digital processors, however. These digital processors can be programmed individually and operated in concert to achieve real-time simulation of wind turbine systems. Because of this programmability, WEST-3 is very much more flexible and general than its two predecessors. The design features of WEST-3 are described to show how the system produces high-speed solutions of nonlinear time-domain equations. WEST-3 has two very fast Computational Units (CU's) that use minicomputer technology plus special architectural features that make them many times faster than a microcomputer. These CU's are needed to perform the complex computations associated with the wind turbine rotor system in real time. The parallel architecture of the CU causes several tasks to be done in each cycle, including an IO operation and the combination of a multiply, add, and store. The WEST-3 simulator can be expanded at any time for additional computational power. This is possible because the CU's interfaced to each other and to other portions of the simulation using special serial buses. These buses can be 'patched' together in essentially any configuration (in a manner very similar to the programming methods used in analog computation) to balance the input/ output requirements. CU's can be added in any number to share a given computational load. This flexible bus feature is very different from many other parallel processors which usually have a throughput limit because of rigid bus architecture.

  9. Design distributed simulation platform for vehicle management system

    NASA Astrophysics Data System (ADS)

    Wen, Zhaodong; Wang, Zhanlin; Qiu, Lihua

    2006-11-01

    Next generation military aircraft requires the airborne management system high performance. General modules, data integration, high speed data bus and so on are needed to share and manage information of the subsystems efficiently. The subsystems include flight control system, propulsion system, hydraulic power system, environmental control system, fuel management system, electrical power system and so on. The unattached or mixed architecture is changed to integrated architecture. That means the whole airborne system is regarded into one system to manage. So the physical devices are distributed but the system information is integrated and shared. The process function of each subsystem are integrated (including general process modules, dynamic reconfiguration), furthermore, the sensors and the signal processing functions are shared. On the other hand, it is a foundation for power shared. Establish a distributed vehicle management system using 1553B bus and distributed processors which can provide a validation platform for the research of airborne system integrated management. This paper establishes the Vehicle Management System (VMS) simulation platform. Discuss the software and hardware configuration and analyze the communication and fault-tolerant method.

  10. Cache Sharing and Isolation Tradeoffs in Multicore Mixed-Criticality Systems

    DTIC Science & Technology

    2015-05-01

    form of lockdown registers, to provide way-based partitioning. These alternatives are illustrated in Fig. 1 with respect to a quad-core ARM Cortex A9... processor (as we do for Level-A and -B tasks), but they did not consider MC systems. Altmeyer et al. [1] considered uniprocessor scheduling on a system with a...framework. We randomly generated task sets and determined the fraction that were schedulable on our target hardware platform, the quad-core ARM Cortex A9

  11. Broca's area: a supramodal hierarchical processor?

    PubMed

    Tettamanti, Marco; Weniger, Dorothea

    2006-05-01

    Despite the presence of shared characteristics across the different domains modulating Broca's area activity (e.g., structural analogies, as between language and music, or representational homologies, as between action execution and action observation), the question of what exactly the common denominator of such diverse brain functions is, with respect to the function of Broca's area, remains largely a debated issue. Here, we suggest that an important computational role of Broca's area may be to process hierarchical structures in a wide range of functional domains.

  12. Multiple Microcomputer Control Algorithm.

    DTIC Science & Technology

    1979-09-01

    discrete and semaphore supervisor calls can be used with tasks in separate processors, in which case they are maintained in shared memory. Operations on ...the source or destination operand specifier of each mode in most cases . However, four of the 16 general register addressing modes and one of the 8 pro...instruction time is based on the specified usage factors and the best cast, and worst case execution times for the instruc- 1I 5 1NAVTRAEQZJ1PCrN M’.V7~j

  13. EndNote 7.0.

    PubMed

    Eapen, Bell Raj

    2006-01-01

    EndNote is a useful software for online literature search and efficient bibliography management. It helps to format the bibliography according to the citation style of each journal. EndNote stores references in a library file, which can be shared with others. It can connect to online resources like PubMed and retrieve search results as per the search criteria. It can also effortlessly integrate with popular word processors like MS Word. The Indian Journal of Dermatology, Venereology and Leprology website has a provision to import references to EndNote.

  14. Development and evaluation of a fault-tolerant multiprocessor (FTMP) computer. Volume 1: FTMP principles of operation

    NASA Technical Reports Server (NTRS)

    Smith, T. B., Jr.; Lala, J. H.

    1983-01-01

    The basic organization of the fault tolerant multiprocessor, (FTMP) is that of a general purpose homogeneous multiprocessor. Three processors operate on a shared system (memory and I/O) bus. Replication and tight synchronization of all elements and hardware voting is employed to detect and correct any single fault. Reconfiguration is then employed to repair a fault. Multiple faults may be tolerated as a sequence of single faults with repair between fault occurrences.

  15. The FOSS GIS Workbench on the GFZ Load Sharing Facility compute cluster

    NASA Astrophysics Data System (ADS)

    Löwe, P.; Klump, J.; Thaler, J.

    2012-04-01

    Compute clusters can be used as GIS workbenches, their wealth of resources allow us to take on geocomputation tasks which exceed the limitations of smaller systems. To harness these capabilities requires a Geographic Information System (GIS), able to utilize the available cluster configuration/architecture and a sufficient degree of user friendliness to allow for wide application. In this paper we report on the first successful porting of GRASS GIS, the oldest and largest Free Open Source (FOSS) GIS project, onto a compute cluster using Platform Computing's Load Sharing Facility (LSF). In 2008, GRASS6.3 was installed on the GFZ compute cluster, which at that time comprised 32 nodes. The interaction with the GIS was limited to the command line interface, which required further development to encapsulate the GRASS GIS business layer to facilitate its use by users not familiar with GRASS GIS. During the summer of 2011, multiple versions of GRASS GIS (v 6.4, 6.5 and 7.0) were installed on the upgraded GFZ compute cluster, now consisting of 234 nodes with 480 CPUs providing 3084 cores. The GFZ compute cluster currently offers 19 different processing queues with varying hardware capabilities and priorities, allowing for fine-grained scheduling and load balancing. After successful testing of core GIS functionalities, including the graphical user interface, mechanisms were developed to deploy scripted geocomputation tasks onto dedicated processing queues. The mechanisms are based on earlier work by NETELER et al. (2008). A first application of the new GIS functionality was the generation of maps of simulated tsunamis in the Mediterranean Sea for the Tsunami Atlas of the FP-7 TRIDEC Project (www.tridec-online.eu). For this, up to 500 processing nodes were used in parallel. Further trials included the processing of geometrically complex problems, requiring significant amounts of processing time. The GIS cluster successfully completed all these tasks, with processing times lasting up to full 20 CPU days. The deployment of GRASS GIS on a compute cluster allows our users to tackle GIS tasks previously out of reach of single workstations. In addition, this GRASS GIS cluster implementation will be made available to other users at GFZ in the course of 2012. It will thus become a research utility in the sense of "Software as a Service" (SaaS) and can be seen as our first step towards building a GFZ corporate cloud service.

  16. Managing variation in demand: lessons from the UK National Health Service.

    PubMed

    Walley, Paul; Silvester, Kate; Steyn, Richard

    2006-01-01

    Managers within the U.S. healthcare system are becoming more aware of the impact of variation in demand on healthcare processes. The UK National Health Service provides a prime example of a system that has experienced the consequences when the issue is not dealt with satisfactorily, having suffered from excessive queues for a prolonged period. These delays are mostly caused by a lack of attention to variation and inappropriate responses to the queues, rather than a capacity shortage. A number of collaborative programs recently have come to grips with many of the causes of the queues in both elective care and emergency care. Although there are still areas that need large-scale improvement, good progress has been made, especially within emergency care. The authors of this article have acted as technical advisors to a number of these improvement programs and have been able to document many of the practices that have helped to reduce or eliminate unnecessary queues and delays across the 200 sites in England that have 24-hour emergency care facilities. Local program managers at these sites continuously reported progress for a period of 18 months. A number of important lessons for both the design and control of healthcare processes have emerged from the collaborative work. These lessons focus on understanding and measurement of demand, capacity planning, reduction of introduced variation, segmentation and streaming of work, process design, capacity yield management, and measurement of variation.

  17. Random early detection for congestion avoidance in wired networks: a discretized pursuit learning-automata-like solution.

    PubMed

    Misra, Sudip; Oommen, B John; Yanamandra, Sreekeerthy; Obaidat, Mohammad S

    2010-02-01

    In this paper, we present a learning-automata-like The reason why the mechanism is not a pure LA, but rather why it yet mimics one, will be clarified in the body of this paper. (LAL) mechanism for congestion avoidance in wired networks. Our algorithm, named as LAL Random Early Detection (LALRED), is founded on the principles of the operations of existing RED congestion-avoidance mechanisms, augmented with a LAL philosophy. The primary objective of LALRED is to optimize the value of the average size of the queue used for congestion avoidance and to consequently reduce the total loss of packets at the queue. We attempt to achieve this by stationing a LAL algorithm at the gateways and by discretizing the probabilities of the corresponding actions of the congestion-avoidance algorithm. At every time instant, the LAL scheme, in turn, chooses the action that possesses the maximal ratio between the number of times the chosen action is rewarded and the number of times that it has been chosen. In LALRED, we simultaneously increase the likelihood of the scheme converging to the action, which minimizes the number of packet drops at the gateway. Our approach helps to improve the performance of congestion avoidance by adaptively minimizing the queue-loss rate and the average queue size. Simulation results obtained using NS2 establish the improved performance of LALRED over the traditional RED methods which were chosen as the benchmarks for performance comparison purposes.

  18. Load Balancing Strategies for Multiphase Flows on Structured Grids

    NASA Astrophysics Data System (ADS)

    Olshefski, Kristopher; Owkes, Mark

    2017-11-01

    The computation time required to perform large simulations of complex systems is currently one of the leading bottlenecks of computational research. Parallelization allows multiple processing cores to perform calculations simultaneously and reduces computational times. However, load imbalances between processors waste computing resources as processors wait for others to complete imbalanced tasks. In multiphase flows, these imbalances arise due to the additional computational effort required at the gas-liquid interface. However, many current load balancing schemes are only designed for unstructured grid applications. The purpose of this research is to develop a load balancing strategy while maintaining the simplicity of a structured grid. Several approaches are investigated including brute force oversubscription, node oversubscription through Message Passing Interface (MPI) commands, and shared memory load balancing using OpenMP. Each of these strategies are tested with a simple one-dimensional model prior to implementation into the three-dimensional NGA code. Current results show load balancing will reduce computational time by at least 30%.

  19. Advanced data management system architectures testbed

    NASA Technical Reports Server (NTRS)

    Grant, Terry

    1990-01-01

    The objective of the Architecture and Tools Testbed is to provide a working, experimental focus to the evolving automation applications for the Space Station Freedom data management system. Emphasis is on defining and refining real-world applications including the following: the validation of user needs; understanding system requirements and capabilities; and extending capabilities. The approach is to provide an open, distributed system of high performance workstations representing both the standard data processors and networks and advanced RISC-based processors and multiprocessor systems. The system provides a base from which to develop and evaluate new performance and risk management concepts and for sharing the results. Participants are given a common view of requirements and capability via: remote login to the testbed; standard, natural user interfaces to simulations and emulations; special attention to user manuals for all software tools; and E-mail communication. The testbed elements which instantiate the approach are briefly described including the workstations, the software simulation and monitoring tools, and performance and fault tolerance experiments.

  20. Concurrent computation of attribute filters on shared memory parallel machines.

    PubMed

    Wilkinson, Michael H F; Gao, Hui; Hesselink, Wim H; Jonker, Jan-Eppo; Meijster, Arnold

    2008-10-01

    Morphological attribute filters have not previously been parallelized, mainly because they are both global and non-separable. We propose a parallel algorithm that achieves efficient parallelism for a large class of attribute filters, including attribute openings, closings, thinnings and thickenings, based on Salembier's Max-Trees and Min-trees. The image or volume is first partitioned in multiple slices. We then compute the Max-trees of each slice using any sequential Max-Tree algorithm. Subsequently, the Max-trees of the slices can be merged to obtain the Max-tree of the image. A C-implementation yielded good speed-ups on both a 16-processor MIPS 14000 parallel machine, and a dual-core Opteron-based machine. It is shown that the speed-up of the parallel algorithm is a direct measure of the gain with respect to the sequential algorithm used. Furthermore, the concurrent algorithm shows a speed gain of up to 72 percent on a single-core processor, due to reduced cache thrashing.

  1. Parallelization of a Monte Carlo particle transport simulation code

    NASA Astrophysics Data System (ADS)

    Hadjidoukas, P.; Bousis, C.; Emfietzoglou, D.

    2010-05-01

    We have developed a high performance version of the Monte Carlo particle transport simulation code MC4. The original application code, developed in Visual Basic for Applications (VBA) for Microsoft Excel, was first rewritten in the C programming language for improving code portability. Several pseudo-random number generators have been also integrated and studied. The new MC4 version was then parallelized for shared and distributed-memory multiprocessor systems using the Message Passing Interface. Two parallel pseudo-random number generator libraries (SPRNG and DCMT) have been seamlessly integrated. The performance speedup of parallel MC4 has been studied on a variety of parallel computing architectures including an Intel Xeon server with 4 dual-core processors, a Sun cluster consisting of 16 nodes of 2 dual-core AMD Opteron processors and a 200 dual-processor HP cluster. For large problem size, which is limited only by the physical memory of the multiprocessor server, the speedup results are almost linear on all systems. We have validated the parallel implementation against the serial VBA and C implementations using the same random number generator. Our experimental results on the transport and energy loss of electrons in a water medium show that the serial and parallel codes are equivalent in accuracy. The present improvements allow for studying of higher particle energies with the use of more accurate physical models, and improve statistics as more particles tracks can be simulated in low response time.

  2. Integrated Payload Data Handling Systems Using Software Partitioning

    NASA Astrophysics Data System (ADS)

    Taylor, Alun; Hann, Mark; Wishart, Alex

    2015-09-01

    An integrated Payload Data Handling System (I-PDHS) is one in which multiple instruments share a central payload processor for their on-board data processing tasks. This offers a number of advantages over the conventional decentralised architecture. Savings in payload mass and power can be realised because the total processing resource is matched to the requirements, as opposed to the decentralised architecture here the processing resource is in effect the sum of all the applications. Overall development cost can be reduced using a common processor. At individual instrument level the potential benefits include a standardised application development environment, and the opportunity to run the instrument data handling application on a fully redundant and more powerful processing platform [1]. This paper describes a joint program by SCISYS UK Limited, Airbus Defence and Space, Imperial College London and RAL Space to implement a realistic demonstration of an I-PDHS using engineering models of flight instruments (a magnetometer and camera) and a laboratory demonstrator of a central payload processor which is functionally representative of a flight design. The objective is to raise the Technology Readiness Level of the centralised data processing technique by address the key areas of task partitioning to prevent fault propagation and the use of a common development process for the instrument applications. The project is supported by a UK Space Agency grant awarded under the National Space Technology Program SpaceCITI scheme. [1].

  3. Optimization of the Multi-Spectral Euclidean Distance Calculation for FPGA-based Spaceborne Systems

    NASA Technical Reports Server (NTRS)

    Cristo, Alejandro; Fisher, Kevin; Perez, Rosa M.; Martinez, Pablo; Gualtieri, Anthony J.

    2012-01-01

    Due to the high quantity of operations that spaceborne processing systems must carry out in space, new methodologies and techniques are being presented as good alternatives in order to free the main processor from work and improve the overall performance. These include the development of ancillary dedicated hardware circuits that carry out the more redundant and computationally expensive operations in a faster way, leaving the main processor free to carry out other tasks while waiting for the result. One of these devices is SpaceCube, a FPGA-based system designed by NASA. The opportunity to use FPGA reconfigurable architectures in space allows not only the optimization of the mission operations with hardware-level solutions, but also the ability to create new and improved versions of the circuits, including error corrections, once the satellite is already in orbit. In this work, we propose the optimization of a common operation in remote sensing: the Multi-Spectral Euclidean Distance calculation. For that, two different hardware architectures have been designed and implemented in a Xilinx Virtex-5 FPGA, the same model of FPGAs used by SpaceCube. Previous results have shown that the communications between the embedded processor and the circuit create a bottleneck that affects the overall performance in a negative way. In order to avoid this, advanced methods including memory sharing, Native Port Interface (NPI) connections and Data Burst Transfers have been used.

  4. Merlin - Massively parallel heterogeneous computing

    NASA Technical Reports Server (NTRS)

    Wittie, Larry; Maples, Creve

    1989-01-01

    Hardware and software for Merlin, a new kind of massively parallel computing system, are described. Eight computers are linked as a 300-MIPS prototype to develop system software for a larger Merlin network with 16 to 64 nodes, totaling 600 to 3000 MIPS. These working prototypes help refine a mapped reflective memory technique that offers a new, very general way of linking many types of computer to form supercomputers. Processors share data selectively and rapidly on a word-by-word basis. Fast firmware virtual circuits are reconfigured to match topological needs of individual application programs. Merlin's low-latency memory-sharing interfaces solve many problems in the design of high-performance computing systems. The Merlin prototypes are intended to run parallel programs for scientific applications and to determine hardware and software needs for a future Teraflops Merlin network.

  5. A Parallel Saturation Algorithm on Shared Memory Architectures

    NASA Technical Reports Server (NTRS)

    Ezekiel, Jonathan; Siminiceanu

    2007-01-01

    Symbolic state-space generators are notoriously hard to parallelize. However, the Saturation algorithm implemented in the SMART verification tool differs from other sequential symbolic state-space generators in that it exploits the locality of ring events in asynchronous system models. This paper explores whether event locality can be utilized to efficiently parallelize Saturation on shared-memory architectures. Conceptually, we propose to parallelize the ring of events within a decision diagram node, which is technically realized via a thread pool. We discuss the challenges involved in our parallel design and conduct experimental studies on its prototypical implementation. On a dual-processor dual core PC, our studies show speed-ups for several example models, e.g., of up to 50% for a Kanban model, when compared to running our algorithm only on a single core.

  6. A FairShare Scheduling Service for OpenNebula

    NASA Astrophysics Data System (ADS)

    Bagnasco, S.; Vallero, S.; Zaccolo, V.

    2017-10-01

    In the ideal limit of infinite resources, multi-tenant applications are able to scale in/out on a Cloud driven only by their functional requirements. While a large Public Cloud may be a reasonable approximation of this condition, small scientific computing centres usually work in a saturated regime. In this case, an advanced resource allocation policy is needed in order to optimize the use of the data centre. The general topic of advanced resource scheduling is addressed by several components of the EU-funded INDIGO-DataCloud project. In this contribution, we describe the FairShare Scheduler Service (FaSS) for OpenNebula (ONE). The service must satisfy resource requests according to an algorithm which prioritizes tasks according to an initial weight and to the historical resource usage of the project. The software was designed to be less intrusive as possible in the ONE code. We keep the original ONE scheduler implementation to match requests to available resources, but the queue of pending jobs to be processed is the one ordered according to priorities as delivered by the FaSS. The FaSS implementation is still being finalized and in this contribution we describe the functional and design requirements the module should satisfy, as well as its high-level architecture.

  7. Area-Efficient VLSI Computation.

    DTIC Science & Technology

    1981-10-01

    to the bus of a computer system. 5 Table 1-2: Definition of the three- sorter . 7 Figure 1-3: A real-time systolic priority queue. 7 Figure 1-4: The...ca.pable of sorting three elements. The iree- sorter has three inputs X, Y, and Z and prduccs tlicc oitputs X’. Y’, and Z’ which are the miniumn, median. Mnd...in Section L4. Figure 1-3 shows how three- sorters are interconnected to make a systolic priority queue. In the figure, the outputs from the top. middle

  8. Where does the waiting list begin? A short review of the dynamics and organization of modern waiting lists.

    PubMed

    Rotstein, Dalia L; Alter, David A

    2006-06-01

    Waiting for medical care is the by-product of system rationing, where demand exceeds supply. In this short report we expand on the conventional concept of the queue, by focusing on the regulation of demand and by incorporating a funnel and spout analogy. Real-world examples are used to illustrate the infancy of funnel or demand-side reform initiatives targeting the queue, and the suggestion is made that policy needs to address the concept of 'waiting' much earlier in the treatment cycle.

  9. Integration of Openstack cloud resources in BES III computing cluster

    NASA Astrophysics Data System (ADS)

    Li, Haibo; Cheng, Yaodong; Huang, Qiulan; Cheng, Zhenjing; Shi, Jingyan

    2017-10-01

    Cloud computing provides a new technical means for data processing of high energy physics experiment. However, the resource of each queue is fixed and the usage of the resource is static in traditional job management system. In order to make it simple and transparent for physicist to use, we developed a virtual cluster system (vpmanager) to integrate IHEPCloud and different batch systems such as Torque and HTCondor. Vpmanager provides dynamic virtual machines scheduling according to the job queue. The BES III use case results show that resource efficiency is greatly improved.

  10. Regenerative Simulation of Response Times in Networks of Queues.

    DTIC Science & Technology

    1979-11-01

    i jobs at center 1. Nov consider the network of queues in Figure 2.2, formulated (Lewis and Shedler ( 1971 )) as a model of system overhead in...7.2 leading to point estimates and confidence intervals for the quantity r(f) are that the pairs of random variables {( V(fHk) : kall (9.2.3) are...189 Next we show that P’=P. Since P ’m"CIP for all i, we can use the Skorohod representation theorem (see Skorohod (1956) or Billingsley ( 1971 )) to

  11. Markovian Queues with Arrival Dependence

    DTIC Science & Technology

    1976-03-01

    adding together the three balance equations for P 2o’ ^21’ "^22 as ^°ll°ws ’ 1 20 2 21 <W P21= XP10 + *2P22 H- ( ^ l^ 2 )p22 = Xp11 "lP20 +UlP21 +V22...REPORT DOCUMENTATION PAGE READ INSTRUCTIONSBEFORE COMPLETING FORM 1 REPORT NUMBER 2 . GOVT ACCESSION NO. 3. RECIPIENT’S CATALOG NUMBER 4. TITLE (and...ADDITIONAL FACTS CONCERNING THE TRANSIENT DISTRIBUTION OF WAITING TIMES FOR ARRIVING CUSTOMERS 2 ? IV. THE TWO CHANNEL SERVER QUEUE WITH SINGLE

  12. Delay decomposition at a single server queue with constant service time and multiple inputs. [Waiting time on computer network

    NASA Technical Reports Server (NTRS)

    Ziegler, C.; Schilling, D. L.

    1977-01-01

    Two networks consisting of single server queues, each with a constant service time, are considered. The external inputs to each network are assumed to follow some general probability distribution. Several interesting equivalencies that exist between the two networks considered are derived. This leads to the introduction of an important concept in delay decomposition. It is shown that the waiting time experienced by a customer can be decomposed into two basic components called self delay and interference delay.

  13. Channel Allocation in Wireless Integrated Services Networks for Low-Bit-Rate Applications.

    DTIC Science & Technology

    1998-06-01

    server remains idle until the beginning of the next slot, even if cells arrive in the meanwhile.7 The server is assumed to be non - preemptive , i.e., it...If the ToE of the cell is smaller than 1/C^(the service time): i) Discard the cell. 2. Sort the remaining cells in the queue in a non -decreasing...126 Next, the cell-loss-probability ratios (CLPR) of non -empty sources (i.e., having at least one cell in the queue ) defined as ratios between the

  14. DSN command system Mark III-78. [data processing

    NASA Technical Reports Server (NTRS)

    Stinnett, W. G.

    1978-01-01

    The Deep Space Network command Mark III-78 data processing system includes a capability for a store-and-forward handling method. The functions of (1) storing the command files at a Deep Space station; (2) attaching the files to a queue; and (3) radiating the commands to the spacecraft are straightforward. However, the total data processing capability is a result of assuming worst case, failure-recovery, or nonnominal operating conditions. Optional data processing functions include: file erase, clearing the queue, suspend radiation, command abort, resume command radiation, and close window time override.

  15. Scheduling and control strategies for the departure problem in air traffic control

    NASA Astrophysics Data System (ADS)

    Bolender, Michael Alan

    Two problems relating to the departure problem in air traffic control automation are examined. The first problem that is addressed is the scheduling of aircraft for departure. The departure operations at a major US hub airport are analyzed, and a discrete event simulation of the departure operations is constructed. Specifically, the case where there is a single departure runway is considered. The runway is fed by two queues of aircraft. Each queue, in turn, is fed by a single taxiway. Two salient areas regarding scheduling are addressed. The first is the construction of optimal departure sequences for the aircraft that are queued. Several greedy search algorithms are designed to minimize the total time to depart a set of queued aircraft. Each algorithm has a different set of heuristic rules to resolve situations within the search space whenever two branches of the search tree with equal edge costs are encountered. These algorithms are then compared and contrasted with a genetic search algorithm in order to assess the performance of the heuristics. This is done in the context of a static departure problem where the length of the departure queue is fixed. A greedy algorithm which deepens the search whenever two branches of the search tree with non-unique costs are encountered is shown to outperform the other heuristic algorithms. This search strategy is then implemented in the discrete event simulation. A baseline performance level is established, and a sensitivity analysis is performed by implementing changes in traffic mix, routing, and miles-in-trail restrictions for comparison. It is concluded that to minimize the average time spent in the queue for different traffic conditions, a queue assignment algorithm is needed to maintain an even balance of aircraft in the queues. A necessary consideration is to base queue assignment upon traffic management restrictions such as miles-in-trail constraints. The second problem addresses the technical challenges associated with merging departure aircraft onto their filed routes in a congested airspace environment. Conflicts between departures and en route aircraft within the Center airspace are analyzed. Speed control, holding the aircraft; at an intermediate altitude, re-routing, and vectoring are posed as possible deconfliction maneuvers. A cost assessment of these merge strategies, which are based upon 4D fight management and conflict detection and resolution principles, is given. Several merge conflicts are studied and a cost for each resolution is computed. It is shown that vectoring tends to be the most expensive resolution technique. Altitude hold is simple, costs less than vectoring, but may require a long time for the aircraft to achieve separation. Re-routing is the simplest, and provides the most cost benefit since the aircraft flies a shorter distance than if it had followed its filed route. Speed control is shown to be ineffective as a means of increasing separation, but is effective for maintaining separation between aircraft. In addition, the affects of uncertainties on the cost are assessed. The analysis shows that cost is invariant with the decision time.

  16. Adaptive Aggregation Routing to Reduce Delay for Multi-Layer Wireless Sensor Networks.

    PubMed

    Li, Xujing; Liu, Anfeng; Xie, Mande; Xiong, Neal N; Zeng, Zhiwen; Cai, Zhiping

    2018-04-16

    The quality of service (QoS) regarding delay, lifetime and reliability is the key to the application of wireless sensor networks (WSNs). Data aggregation is a method to effectively reduce the data transmission volume and improve the lifetime of a network. In the previous study, a common strategy required that data wait in the queue. When the length of the queue is greater than or equal to the predetermined aggregation threshold ( N t ) or the waiting time is equal to the aggregation timer ( T t ), data are forwarded at the expense of an increase in the delay. The primary contributions of the proposed Adaptive Aggregation Routing (AAR) scheme are the following: (a) the senders select the forwarding node dynamically according to the length of the data queue, which effectively reduces the delay. In the AAR scheme, the senders send data to the nodes with a long data queue. The advantages are that first, the nodes with a long data queue need a small amount of data to perform aggregation; therefore, the transmitted data can be fully utilized to make these nodes aggregate. Second, this scheme balances the aggregating and data sending load; thus, the lifetime increases. (b) An improved AAR scheme is proposed to improve the QoS. The aggregation deadline ( T t ) and the aggregation threshold ( N t ) are dynamically changed in the network. In WSNs, nodes far from the sink have residual energy because these nodes transmit less data than the other nodes. In the improved AAR scheme, the nodes far from the sink have a small value of T t and N t to reduce delay, and the nodes near the sink are set to a large value of T t and N t to reduce energy consumption. Thus, the end to end delay is reduced, a longer lifetime is achieved, and the residual energy is fully used. Simulation results demonstrate that compared with the previous scheme, the performance of the AAR scheme is improved. This scheme reduces the delay by 14.91%, improves the lifetime by 30.91%, and increases energy efficiency by 76.40%.

  17. Effect of the time of day and queue position in the endoscopic schedule on the performance characteristics of endoscopic ultrasound-guided fine-needle aspiration for diagnosing pancreatic malignancies

    PubMed Central

    Korenblit, Jason; Tholey, Danielle M.; Tolin, Joanna; Loren, David; Kowalski, Thomas; Adler, Douglas G.; Davolos, Julie; Siddiqui, Ali A.

    2016-01-01

    Background and Objectives: Recent reports have indicated that the time of day may impact the detection rate of abnormal cytology on gynecologic cytology samples. The aim of this study was to determine if procedure time or queue position affected the performance characteristics of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) for diagnosing solid pancreatic malignancies. Patients and Methods: We conducted a retrospective study evaluating patients with solid pancreatic lesions in whom EUS-FNA was performed. Three timing variables were evaluated as surrogate markers for endoscopist fatigue: Procedure start times, morning versus afternoon procedures, and endoscopy queue position. Statistical analyses were performed to determine whether the timing variables predicted performance characteristics of EUS-FNA. Results: We identified 609 patients (mean age: 65.8 years, 52.1% males) with solid pancreatic lesions who underwent EUS-FNA. The sensitivity of EUS-FNA was 100% for procedures that started at 7 AM while cases that started at 4 PM had a sensitivity of 81%. Using start time on a continuous scale, each elapsed hour was associated with a 1.9% decrease in EUS-FNA sensitivity (P = 0.003). Similarly, a 10% reduction in EUS-FNA sensitivity was detected between morning and afternoon procedures (92% vs. 82% respectively, P = 0.0006). A linear regression comparing the procedure start time and diagnostic accuracy revealed a decrease of approximately 1.7% in procedure accuracy for every hour later a procedure was started. A 16% reduction in EUS-FNA accuracy was detected between morning and afternoon procedures (100% vs. 84% respectively, P = 0.0009). When the queue position was assessed, a 2.4% reduction in accuracy was noted for each increase in the queue position (P = 0.013). Conclusion: Sensitivity and diagnostic accuracy of EUS-FNA for solid pancreatic lesions decline with progressively later EUS starting times and increasing numbers of procedures before a given EUS, potentially from endoscopist fatigue and cytotechnologist fatigue. PMID:27080605

  18. Adaptive Aggregation Routing to Reduce Delay for Multi-Layer Wireless Sensor Networks

    PubMed Central

    Li, Xujing; Xie, Mande; Zeng, Zhiwen; Cai, Zhiping

    2018-01-01

    The quality of service (QoS) regarding delay, lifetime and reliability is the key to the application of wireless sensor networks (WSNs). Data aggregation is a method to effectively reduce the data transmission volume and improve the lifetime of a network. In the previous study, a common strategy required that data wait in the queue. When the length of the queue is greater than or equal to the predetermined aggregation threshold (Nt) or the waiting time is equal to the aggregation timer (Tt), data are forwarded at the expense of an increase in the delay. The primary contributions of the proposed Adaptive Aggregation Routing (AAR) scheme are the following: (a) the senders select the forwarding node dynamically according to the length of the data queue, which effectively reduces the delay. In the AAR scheme, the senders send data to the nodes with a long data queue. The advantages are that first, the nodes with a long data queue need a small amount of data to perform aggregation; therefore, the transmitted data can be fully utilized to make these nodes aggregate. Second, this scheme balances the aggregating and data sending load; thus, the lifetime increases. (b) An improved AAR scheme is proposed to improve the QoS. The aggregation deadline (Tt) and the aggregation threshold (Nt) are dynamically changed in the network. In WSNs, nodes far from the sink have residual energy because these nodes transmit less data than the other nodes. In the improved AAR scheme, the nodes far from the sink have a small value of Tt and Nt to reduce delay, and the nodes near the sink are set to a large value of Tt and Nt to reduce energy consumption. Thus, the end to end delay is reduced, a longer lifetime is achieved, and the residual energy is fully used. Simulation results demonstrate that compared with the previous scheme, the performance of the AAR scheme is improved. This scheme reduces the delay by 14.91%, improves the lifetime by 30.91%, and increases energy efficiency by 76.40%. PMID:29659535

  19. Considerations for Future Climate Data Stewardship

    NASA Astrophysics Data System (ADS)

    Halem, M.; Nguyen, P. T.; Chapman, D. R.

    2009-12-01

    In this talk, we will describe the lessons learned based on processing and generating a decade of gridded AIRS and MODIS IR sounding data. We describe the challenges faced in accessing and sharing very large data sets, maintaining data provenance under evolving technologies, obtaining access to legacy calibration data and the permanent preservation of Earth science data records for on demand services. These lessons suggest a new approach to data stewardship will be required for the next decade of hyper spectral instruments combined with cloud resolving models. It will not be sufficient for stewards of future data centers to just provide the public with access to archived data but our experience indicates that data needs to reside close to computers with ultra large disc farms and tens of thousands of processors to deliver complex services on demand over very high speed networks much like the offerings of search engines today. Over the first decade of the 21st century, petabyte data records were acquired from the AIRS instrument on Aqua and the MODIS instrument on Aqua and Terra. NOAA data centers also maintain petabytes of operational IR sounders collected over the past four decades. The UMBC Multicore Computational Center (MC2) developed a Service Oriented Atmospheric Radiance gridding system (SOAR) to allow users to select IR sounding instruments from multiple archives and choose space-time- spectral periods of Level 1B data to download, grid, visualize and analyze on demand. Providing this service requires high data rate bandwidth access to the on line disks at Goddard. After 10 years, cost effective disk storage technology finally caught up with the MODIS data volume making it possible for Level 1B MODIS data to be available on line. However, 10Ge fiber optic networks to access large volumes of data are still not available from CSFC to serve the broader community. Data transfer rates are well below 10MB/s limiting their usefulness for climate studies. During this decade, processor performance hit a power wall leading computer vendors to design multicore processor chips. High performance computer systems obtained petaflop performance by clustering tens of thousands of multicore processor chips. Thus, power consumption and autonomic recovery from processor and disc failures have become major cost and technical considerations for future data archives. To address these new architecture requirements, a transparent parallel programming paradigm, the Hadoop MapReduce cloud computing system, became available as an open S/W system. In addition, the Hadoop File System and manages the distribution of data to these processors as well as backs up the processing in the event of any processor or disc failure. However, to employ this paradigm, the data needs to be stored on the computer system. We conclude this talk with a climate data preservation approach that addresses the scalability crisis to exabyte data requirements for the next decade based on projections of processor, disc data density and bandwidth doubling rates.

  20. Do as I say, not as I do: a survey of public impressions of queue-jumping and preferential access.

    PubMed

    Friedman, Steven Marc; Schofield, Lee; Tirkos, Sam

    2007-10-01

    The Canada Health Act legislates that Canadian citizens have access to healthcare that is publicly administered, universal, comprehensive, portable, and accessible (i.e. unimpeded by financial, clinical, or social factors). We surveyed public impressions and practices regarding preferential access to healthcare and queue jumping. Households were randomly selected from the Toronto telephone directory. English speakers aged 18 years or older were solicited for a standardized telephone survey. Statistical analysis was performed using SPSS and SAS. Fifteen percent (n=101) of 668 solicited were surveyed. Ninety-five percent advocated equal access based on need. Support for queue jumping in the emergency department (ED) was strong for cases of emergency, severe pain, and pediatrics, equivocal for police, and minimal for the homeless, doctors, hospital administrators, and government officials. To improve a position on a waiting list, approximately half surveyed would call a friend who is a doctor, works for a doctor, or is a hospital administrator. Sixteen percent reported having done this. The likelihoods of offering material inducement for preferential access were 30 and 51% for low and high-impact medical scenarios, respectively. The likelihoods of offering nonmaterial inducement were 56 and 71%, respectively. Responses were not associated with sex, occupation, or education. Respondents expressed support for equal access based on need. Policy and scenario-type questions elicited different responses. Expressed beliefs may vary from personal practice. Clearly defined and enforced policies at the hospital and provincial level might enhance principles of fairness in the ED queue.

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