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Sample records for queue dual bus

  1. Study on the calculation models of bus delay at bays using queueing theory and Markov chain.

    PubMed

    Sun, Feng; Sun, Li; Sun, Shao-Wei; Wang, Dian-Hai

    2015-01-01

    Traffic congestion at bus bays has decreased the service efficiency of public transit seriously in China, so it is crucial to systematically study its theory and methods. However, the existing studies lack theoretical model on computing efficiency. Therefore, the calculation models of bus delay at bays are studied. Firstly, the process that buses are delayed at bays is analyzed, and it was found that the delay can be divided into entering delay and exiting delay. Secondly, the queueing models of bus bays are formed, and the equilibrium distribution functions are proposed by applying the embedded Markov chain to the traditional model of queuing theory in the steady state; then the calculation models of entering delay are derived at bays. Thirdly, the exiting delay is studied by using the queueing theory and the gap acceptance theory. Finally, the proposed models are validated using field-measured data, and then the influencing factors are discussed. With these models the delay is easily assessed knowing the characteristics of the dwell time distribution and traffic volume at the curb lane in different locations and different periods. It can provide basis for the efficiency evaluation of bus bays. PMID:25759720

  2. Study on the Calculation Models of Bus Delay at Bays Using Queueing Theory and Markov Chain

    PubMed Central

    Sun, Li; Sun, Shao-wei; Wang, Dian-hai

    2015-01-01

    Traffic congestion at bus bays has decreased the service efficiency of public transit seriously in China, so it is crucial to systematically study its theory and methods. However, the existing studies lack theoretical model on computing efficiency. Therefore, the calculation models of bus delay at bays are studied. Firstly, the process that buses are delayed at bays is analyzed, and it was found that the delay can be divided into entering delay and exiting delay. Secondly, the queueing models of bus bays are formed, and the equilibrium distribution functions are proposed by applying the embedded Markov chain to the traditional model of queuing theory in the steady state; then the calculation models of entering delay are derived at bays. Thirdly, the exiting delay is studied by using the queueing theory and the gap acceptance theory. Finally, the proposed models are validated using field-measured data, and then the influencing factors are discussed. With these models the delay is easily assessed knowing the characteristics of the dwell time distribution and traffic volume at the curb lane in different locations and different periods. It can provide basis for the efficiency evaluation of bus bays. PMID:25759720

  3. MIL-STD-1553 programmable dual redundant remote terminal, bus controller, bus monitor, unit

    NASA Astrophysics Data System (ADS)

    Friedman, S. N.

    The performance, physical and electrical characteristics of the BUS-65600 Superhybrid are described. The Superhybrid is a programmable, fully compliant MIL-STD-1553 Dual Redundant Remote Terminal Unit (RTU), BUS Controller (BC) or BUS Monitor (BM). It requires the BUS-63125 Dual Redundant Monolithic Hybrid Transceiver or two BUS-63102 Universal Transceivers for MIL-STD-1553B or McAir sinusoidal applications. A discussion of the custom Monolithic LSI components implemented in the Superhybrid is included. The special features and capabilities are highlighted, along with special programming options which facilitate a broad array of applications. The BUS-65600 Superhybrid has a Direct Memory Access (DMA) Computer Interface plus necessary control lines which are also described in detail.

  4. MIL-STD-1553 Dual Redundant Remote Terminal Unit, BUS Controller and BUS Monitor Superhybrid

    NASA Astrophysics Data System (ADS)

    Friedman, Steven N.

    This paper describes the performance, physical, and electrical characteristics of the BUS-65600 Superhybrid. The Superhybrid is a programmable, fully compliant MIL-STD-1553 Dual Redundant Remote Terminal Unit (RTU), BUS Controller (BC) and BUS Monitor (BM). The BUS-65600 requires an external transceiver, clock, and transformers to provide a fully functional terminal interface. A discussion of the next generation CMOS Silicon-On-Sapphire (SOS) single monolithic chip RTU/BC/BM is included. The special features and capabilities, along with special package technologies are highlighted. The Superhybrid has a Direct Memory Access computer interface plus special control lines which are fully described.

  5. Codes for a priority queue on a parallel data bus. [Deep Space Network

    NASA Technical Reports Server (NTRS)

    Wallis, D. E.; Taylor, H.

    1979-01-01

    Some codes for arbitration of priorities among subsystem computers or peripheral device controllers connected to a parallel data bus are described. At arbitration time, several subsystems present wire-OR, parallel code words to the bus, and the central computer can identify the subsystem of highest priority and determine which of two or more transmission services the subsystem requires. A mathematical discussion of the optimality of the codes with regard to the number of subsystems that may participate in the scheme for a given number of wires is presented along with the number of services that each subsystem may request.

  6. A dual speed, MIL-STD-1553B compatible fiber optic data bus

    NASA Astrophysics Data System (ADS)

    Blaha, M. S.; Degennaro, C. H.; Utley, S. F.

    A demonstration system of a dual speed, fiber optic data bus is described. This work is based on a previously described concept (1) which envisioned a data bus populated with MIL-STD-1553B avionic components which evolve as equipment is upgraded to higher data rates. The approach described herein provides for the coexistence of bus nodes operating at 1 Mb/s, and 20 Mb/s, on a single fiber bus medium. The 1 Mb/s interface of each node is 1553B compatible, making use of readily available hardware and software. Both existing, 1 Mb/s 1553B compatible interfaces and new equipment operating at 20 Mb/s have been shown to work simultaneously on the single bus structure. The design provides a sound, low-risk method for transitioning from current 1 Mb/s equipment to a unified bus structure incorporating both existing 1553B compatible components and newly designed higher speed equipment.

  7. Interface For Dual-Channel MIL-STD-1553 Data Bus

    NASA Technical Reports Server (NTRS)

    Davies, Bryan L.; Heaps, Timothy L.

    1992-01-01

    Digital electronic subsystem made of commercially available programmable logic arrays and discrete logic devices serves as interface between microprocessor and dual-channel MIL-STD-1553 data bus. Subsystem consumes only 800 mW of power. Provides flexibility in that it is controllable via firmware. Includes only two reading-and-writing ports: one for status and control signals, other for transmission and reception of data.

  8. Development of dual-rate MIL-STD-1773A data bus transceiver

    NASA Astrophysics Data System (ADS)

    Bonebright, Rodney K.; Kim, Jae H.; Hughes, Rod; Clement, Jay W.; Bocek, Thomas M.; Chan, Eric Y.; Nitardy, John H.; Hong, Chi-Shain

    1996-10-01

    Boeing has first developed a space-qualifiable, radiation- hardened, dual-rate MIL-STD-1773A fiber-optic transceiver for military command/response time division multiplexed data bus applications. This will provide an enhancement path from a fixed low data rate MIL-STD-1553 bus to a high data rate MIL-STD-1773 bus with minor modification of terminals supporting the existing function. The transceiver operates at dual-rates of both 1 and 20 Mbps over temperature (minus 25 to plus 85 degrees Celsius), and it shows a large dynamic range of greater than 20 dB in support of 32-node star network; a sensitivity of up to minus 38.7 dBm and a saturation of minus 16.1 dBm (limited mainly by test source power) at BER less than or equal to 1 multiplied by 10-10. These transceivers are currently being utilized for space and military applications at DARPA, NASA, and JPL. In this paper we describe the dual-rate transceiver design requirements, ASIC and hybrid design, and performance test results.

  9. Comparison of FDDI asynchronous mode and DQDB queue arbitrated mode data transmission for metropolitan area network applications

    NASA Astrophysics Data System (ADS)

    Burr, William E.; Wakid, Shukri; Qian, Xiaomei; Vaman, Dhadesugoor

    1994-02-01

    The performance of the FDDI (Fiber Distributed Data Interface) token ring and IEEE 802.6 DQDB (Distributed Queue Dual Bus) protocols are compared using discrete event simulation models. A Metropolitan Area Network (MAN) of 100 km and with 50 stations was modeled. A 100 Mbps channel is used for both networks, with a traffic model with large (1 kbyte) low priority packets and smaller (100 byte) high priority packets. The delay and fairness characteristics of both networks are analyzed.

  10. Measuring in-cabin school bus tailpipe and crankcase PM2.5: a new dual tracer method.

    PubMed

    Ireson, Robert G; Ondov, John M; Zielinska, Barbara; Weaver, Christopher S; Easter, Michael D; Lawson, Douglas R; Hesterberg, Thomas W; Davey, Mark E; Liu, L-J Sally

    2011-05-01

    Exposures of occupants in school buses to on-road vehicle emissions, including emissions from the bus itself, can be substantially greater than those in outdoor settings. A dual tracer method was developed and applied to two school buses in Seattle in 2005 to quantify in-cabin fine particulate matter (PM2.5) concentrations attributable to the buses' diesel engine tailpipe (DPMtp) and crankcase vent (PMck) emissions. The new method avoids the problem of differentiating bus emissions from chemically identical emissions of other vehicles by using a fuel-based organometallic iridium tracer for engine exhaust and by adding deuterated hexatriacontane to engine oil. Source testing results showed consistent PM:tracer ratios for the primary tracer for each type of emissions. Comparisons of the PM:tracer ratios indicated that there was a small amount of unburned lubricating oil emitted from the tailpipe; however, virtually no diesel fuel combustion products were found in the crankcase emissions. For the limited testing conducted here, although PMck emission rates (averages of 0.028 and 0.099 g/km for the two buses) were lower than those from the tailpipe (0.18 and 0.14 g/km), in-cabin PMck concentrations averaging 6.8 microg/m3 were higher than DPMtp (0.91 microg/m3 average). In-cabin DPMtp and PMck concentrations were significantly higher with bus windows closed (1.4 and 12 microg/m3, respectively) as compared with open (0.44 and 1.3 microg/m3, respectively). For comparison, average closed- and open-window in-cabin total PM2.5 concentrations were 26 and 12 microg/m3, respectively. Despite the relatively short in-cabin sampling times, very high sensitivities were achieved, with detection limits of 0.002 microg/m3 for DPMtp and 0.05 microg/m3 for PMck. PMID:21608489

  11. Does the Butcher-on-the-Bus Phenomenon Require a Dual-Process Explanation? A Signal Detection Analysis

    PubMed Central

    Tunney, Richard J.; Mullett, Timothy L.; Moross, Claudia J.; Gardner, Anna

    2012-01-01

    The butcher-on-the-bus is a rhetorical device or hypothetical phenomenon that is often used to illustrate how recognition decisions can be based on different memory processes (Mandler, 1980). The phenomenon describes a scenario in which a person is recognized but the recognition is accompanied by a sense of familiarity or knowing characterized by an absence of contextual details such as the person’s identity. We report two recognition memory experiments that use signal detection analyses to determine whether this phenomenon is evidence for a recollection plus familiarity model of recognition or is better explained by a univariate signal detection model. We conclude that there is an interaction between confidence estimates and remember-know judgments which is not explained fully by either single-process signal detection or traditional dual-process models. PMID:22745631

  12. 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.

  13. 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.

  14. Network Queueing System (NQS)

    NASA Technical Reports Server (NTRS)

    Kingsbury, B.

    1989-01-01

    Program provides batch and device queueing facilities for various computers networked in UNIX environment. Allows network manager to allocate and track resources across network without requiring user to specifically log in on remote target machines.

  15. Dynamics of social queues.

    PubMed

    Toyoizumi, Hiroshi; Field, Jeremy

    2014-04-01

    Queues formed by social wasps to inherit the dominant position in the nest are analyzed by using a transient quasi-birth-and-death (QBD) process. We show that the extended nest lifespan due to division of labor between queen and helpers has a big impact on nest productivity. PMID:24378647

  16. A software bus for thread objects

    NASA Technical Reports Server (NTRS)

    Callahan, John R.; Li, Dehuai

    1995-01-01

    The authors have implemented a software bus for lightweight threads in an object-oriented programming environment that allows for rapid reconfiguration and reuse of thread objects in discrete-event simulation experiments. While previous research in object-oriented, parallel programming environments has focused on direct communication between threads, our lightweight software bus, called the MiniBus, provides a means to isolate threads from their contexts of execution by restricting communications between threads to message-passing via their local ports only. The software bus maintains a topology of connections between these ports. It routes, queues, and delivers messages according to this topology. This approach allows for rapid reconfiguration and reuse of thread objects in other systems without making changes to the specifications or source code. A layered approach that provides the needed transparency to developers is presented. Examples of using the MiniBus are given, and the value of bus architectures in building and conducting simulations of discrete-event systems is discussed.

  17. 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.

  18. Jitter-Conscious Bus Arbitration Scheme for Real-Time Systems

    NASA Astrophysics Data System (ADS)

    Roh, Jong-Ho; Jun, Minje; Bang, Kwanhu; Chung, Eui-Young

    Jitter is the variation of latencies, when real-time Intellectual Properties (IPs) are accessing data from the data storages. It is a critical factor for such IPs from the Quality-of-Service (QoS) perspective. Jitter of a real-time IP can be measured by how frequently it experiences the underflows and overflows from its data queue in read mode and write mode, respectively. Such failures critically depend on the bus arbitration scheme which determines the bus acquisition order of IPs. The proposed idea allows IPs to inform the bus arbiter of the status of their data buffers when they assert bus requests. Such information helps the bus arbiter to determine the bus acquisition order while greatly reducing the jitter. The experimental results show that our method effectively eliminates the overflows and underflows of real-time IPs by dynamically preempting the jitter-critical bus requests.

  19. Message passing with queues and channels

    SciTech Connect

    Dozsa, Gabor J; Heidelberger, Philip; Kumar, Sameer; Ratterman, Joseph D; Steinmacher-Burrow, Burkhard

    2013-02-19

    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 the 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.

  20. Bus Training Handbook.

    ERIC Educational Resources Information Center

    Dorny, Audrea; Cole, ChiKay

    This manual presents guidelines for teaching students with disabilities necessary skills for safe and independent travel on public buses. Six guidelines for teachers include: (1) participate in bus training; (2) use wise and intelligent judgment; (3) utilize the bus checklist; (4) know and teach bus rules; (5) know bus routes; and (6) know bus…

  1. A decentralized software bus based on IP multicas ting

    NASA Technical Reports Server (NTRS)

    Callahan, John R.; Montgomery, Todd

    1995-01-01

    We describe decentralized reconfigurable implementation of a conference management system based on the low-level Internet Protocol (IP) multicasting protocol. IP multicasting allows low-cost, world-wide, two-way transmission of data between large numbers of conferencing participants through the Multicasting Backbone (MBone). Each conference is structured as a software bus -- a messaging system that provides a run-time interconnection model that acts as a separate agent (i.e., the bus) for routing, queuing, and delivering messages between distributed programs. Unlike the client-server interconnection model, the software bus model provides a level of indirection that enhances the flexibility and reconfigurability of a distributed system. Current software bus implementations like POLYLITH, however, rely on a centralized bus process and point-to-point protocols (i.e., TCP/IP) to route, queue, and deliver messages. We implement a software bus called the MULTIBUS that relies on a separate process only for routing and uses a reliable IP multicasting protocol for delivery of messages. The use of multicasting means that interconnections are independent of IP machine addresses. This approach allows reconfiguration of bus participants during system execution without notifying other participants of new IP addresses. The use of IP multicasting also permits an economy of scale in the number of participants. We describe the MULITIBUS protocol elements and show how our implementation performs better than centralized bus implementations.

  2. Queues and Simulations for Secondary School Students

    ERIC Educational Resources Information Center

    Copes, Wayne; And Others

    1986-01-01

    A self-teaching module on queues, dealing with the use of random numbers in the simulation of realistic queueing or waiting-line situations, is described. Both mathematical content and teaching methods are considered. (MNS)

  3. The Bus Stops Here.

    ERIC Educational Resources Information Center

    Milshtein, Amy

    1999-01-01

    Explores some of the factors to consider before school planners decide to buy new school buses. Provides a checklist to help build and maintain a bus fleet. Concludes by addressing bus safety and advertising. (GR)

  4. Transit-bus maintenance

    SciTech Connect

    Purdy, J.E.; Wiegmann, J.D.; Maze, T.H.; Cook, A.R.; List, G.

    1987-01-01

    The 4 papers in the report deal with the following areas; vehicle maintenance: cost relationship and estimating methodology; theory and practice of transit-bus maintenance performance measurement; bus maintenance performance indicators; historical development and current practice; and terrain effects on bus-maintenance performance.

  5. Message passing with queues and channels

    DOEpatents

    Dozsa, Gabor J; Heidelberger, Philip; Kumar, Sameer; Ratterman, Joseph D; Steinmacher-Burow, Burkhard; Wisniewski, Robert W

    2013-09-24

    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 send 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.

  6. Hydrogen powered bus

    ScienceCinema

    None

    2013-11-22

    Take a ride on a new type of bus, fueled by hydrogen. These hydrogen taxis are part of a Department of Energy-funded deployment of hydrogen powered vehicles and fueling infrastructure at nine federal facilities across the country to demonstrate this market-ready advanced technology. Produced and leased by Ford Motor Company , they consist of one 12- passenger bus and one nine-passenger bus. More information at: http://go.usa.gov/Tgr

  7. From Waiting for the Bus to Storming the Bastille: From Sartrean Seriality to the Relationships that Form Classroom Communities

    ERIC Educational Resources Information Center

    Blenkinsop, Sean

    2012-01-01

    One of the tasks of Jean-Paul Sartre's later work was to consider how an individual could live freely within a free community. This paper examines how Sartre describes the process of group formation and the implications of this discussion for education. The paper begins with his metaphor of a bus queue in order to describe a series. Then, by means…

  8. School Bus Safety Report.

    ERIC Educational Resources Information Center

    National Highway Traffic Safety Administration (DOT), Washington, DC.

    This publication provides a summary and update of school bus-safety activities conducted by the National Highway Traffic Safety Administration (NHTSA). This report discusses Congressional mandates and NHTSA's actions to improve school-bus safety (which include programs that affect human behavior and motor-vehicle safety performance), the magnitude…

  9. On retrial queueing model with fuzzy parameters

    NASA Astrophysics Data System (ADS)

    Ke, Jau-Chuan; Huang, Hsin-I.; Lin, Chuen-Horng

    2007-01-01

    This work constructs the membership functions of the system characteristics of a retrial queueing model with fuzzy customer arrival, retrial and service rates. The α-cut approach is used to transform a fuzzy retrial-queue into a family of conventional crisp retrial queues in this context. By means of the membership functions of the system characteristics, a set of parametric non-linear programs is developed to describe the family of crisp retrial queues. A numerical example is solved successfully to illustrate the validity of the proposed approach. Because the system characteristics are expressed and governed by the membership functions, more information is provided for use by management. By extending this model to the fuzzy environment, fuzzy retrial-queue is represented more accurately and analytic results are more useful for system designers and practitioners.

  10. Creative Bus Financing.

    ERIC Educational Resources Information Center

    Malone, Wade

    1982-01-01

    Alternative ways of financing school bus purchases include financing privately through contractors or commercial banks, financing through sources such as insurance companies and pension funds, leasing the buses, or contracting for transportation services. (Author/MLF)

  11. School Bus Safety.

    ERIC Educational Resources Information Center

    Rittner-Heir, Robbin M.

    2001-01-01

    Explains why fewer school students are injured are killed while being transported in school buses than any other mode of transportation. Political and community action in school bus transportation safety is addressed. (GR)

  12. SCSI Communication Test Bus

    NASA Technical Reports Server (NTRS)

    Hua, Chanh V.; D'Ambrose, John J.; Jaworski, Richard C.; Halula, Elaine M.; Thornton, David N.; Heligman, Robert L.; Turner, Michael R.

    1990-01-01

    Small Computer System Interface (SCSI) communication test bus provides high-data-rate, standard interconnection enabling communication among International Business Machines (IBM) Personal System/2 Micro Channel, other devices connected to Micro Channel, test equipment, and host computer. Serves primarily as nonintrusive input/output attachment to PS/2 Micro Channel bus, providing rapid communication for debugger. Opens up possibility of using debugger in real-time applications.

  13. MIL-STD-1553 dynamic bus controller/remote terminal hybrid set

    NASA Astrophysics Data System (ADS)

    Friedman, S. N.

    This paper describes the performance, physical and electrical requirements of a Dual Redundant BUS Interface Unit (BIU) acting as a BUS Controller Interface Unit (BCIU) or Remote Terminal Unit (RTU) between a Motorola 68000 VME BUS and MIL-STD-1553B Multiplex Data Bus. A discussion of how the BIU Hybrid set is programmed, and operates as a BCIU or RTU, will be included. This paper will review Dynamic Bus Control and other Mode Code capabilities. The BIU Hybrid Set interfaces to a 68000 Microprocessor with a VME Bus using programmed I/O transfers. This special interface will be discussed along with the internal Dual Access Memory (4K x 16) used to support the data exchanges between the CPU and the BIU Hybrid Set. The hybrid set's physical size and power requirements will be covered. This includes the present Double Eurocard the BIU function is presently being offered on.

  14. The JCMT observing queue and recipe sequencer

    NASA Astrophysics Data System (ADS)

    Kackley, Russell D.; Rees, Nicholas P.; Walther, Craig; Jenness, Tim

    2004-09-01

    The James Clerk Maxwell Telescope (JCMT), the world's largest sub-mm telescope, will soon be switching operations from a VAX/VMS based control system to a new, Linux-based, Observatory Control System1 (OCS). A critical part of the OCS is the set of tasks that are associated with the observation queue and the observing recipe sequencer: 1) the JCMT observation queue task 2) the JCMT instrument task, 3) the JCMT Observation Sequencer (JOS), and 4) the OCS console task. The JCMT observation queue task serves as a staging area for observations that have been translated from the observer's science program into a form suitable for the various OCS subsystems. The queue task operates by sending the observation at the head of the queue to the JCMT instrument task and then waits for the astronomer to accept the data before removing the observation from the queue. The JCMT instrument task is responsible for running up the set of tasks required to observe with a particular instrument at the JCMT and passing the observation on to the JOS. The JOS is responsible for executing the observing recipe, pausing/continuing the recipe when commanded, and prematurely ending or aborting the observation when commanded. The OCS console task provides the user with a GUI window with which they can control and monitor the observation queue and the observation itself. This paper shows where the observation queue and recipe sequencer fit into the JCMT OCS, presents the design decisions that resulted in the tasks being structured as they are, describes the external interfaces of the four tasks, and details the interaction between the tasks.

  15. 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.

  16. 7. YOSEMITE VALLEY SHUTTLE BUS AT SENTINEL BRIDGE SHUTTLE BUS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. YOSEMITE VALLEY SHUTTLE BUS AT SENTINEL BRIDGE SHUTTLE BUS AND PARKING LOT AREA. LOOKING WNW. GIS: N-37 40 36.2 / W-119 44 45.0 - Yosemite National Park Roads & Bridges, Yosemite Village, Mariposa County, CA

  17. Information theory and queueing theory via generalized geometric programming

    SciTech Connect

    Muhammed, A.A.

    1987-01-01

    The relationships between the generalized geometric programming of E.L. Peterson and two important fields, information theory and queueing theory, are given. Only the finite case is discussed, but the framework is quite general. The infinite case and other topics are given as research problems at the end. Perhaps the most-important problem in information theory is the problem of finding the distribution with maximum uncertainty. More generally the problem of minimizing any generalized f-entropy subject to some linear conditions (equations or inequalities) turn out to be a generalized geometric programming problem. The resulting geometric programming duality provides: a dual problem, a strong duality theory, parametric programming and sensitivity analysis, decomposition principles, and many other aspect of generalized geometric programming. One of the most important problems in queueing theory and stochastic processes is the problem of finding the steady-state distribution. Some classical techniques, such as inverting moment generating functions or solving the steady-state equations, can be illuminated by geometric programming.

  18. Multipurpose satellite bus (MPS)

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The Naval Postgraduate School Advanced Design Project sponsored by the Universities Space Research Association Advanced Design Program is a multipurpose satellite bus (MPS). The design was initiated from a Statement of Work (SOW) developed by the Defense Advanced Research Projects Agency (DARPA). The SOW called for a 'proposal to design a small, low-cost, lightweight, general purpose spacecraft bus capable of accommodating any of a variety of mission payloads. Typical payloads envisioned include those associated with meteorological, communication, surveillance and tracking, target location, and navigation mission areas.' The design project investigates two dissimilar missions, a meteorological payload and a communications payload, mated with a single spacecraft bus with minimal modifications. The MPS is designed for launch aboard the Pegasus Air Launched Vehicle (ALV) or the Taurus Standard Small Launch Vehicle (SSLV).

  19. 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.

  20. Optical bus system LIBSY

    NASA Astrophysics Data System (ADS)

    Wagner, T.

    1985-11-01

    The local area network LIBSY, a protocol transparent ring with controlled access consisting of users, computers, and peripherical devices all connected to an optical bus by the intelligent interface device LICOM is presented. The LICOM contains the interface electronics for a bus compatible adaption to the user computer. The battery-buffered coupling optronics connects the optical fiber and the computer which drives and supervises the decentralized democratically organized data flow in the network. Up to 64 computers or 255 users can be connected to the ring. The levels 1 to 4 of the ISO model for system architecture were implemented by the system.

  1. Bus-Programmable Slave Card

    NASA Technical Reports Server (NTRS)

    Hall, William A.

    1990-01-01

    Slave microprocessors in multimicroprocessor computing system contains modified circuit cards programmed via bus connecting master processor with slave microprocessors. Enables interactive, microprocessor-based, single-loop control. Confers ability to load and run program from master/slave bus, without need for microprocessor development station. Tristate buffers latch all data and information on status. Slave central processing unit never connected directly to bus.

  2. Personal Computer Monitors Instrumentation Bus

    NASA Technical Reports Server (NTRS)

    Conroy, Bruce L.

    1994-01-01

    IBM-compatible personal computer used instead of logic analyzer or other special instrument to monitor IEEE-488 interface data bus that interconnects various pieces of laboratory equipment. Needed is short program for computer, commercial general-purpose interface bus circuit card, and adapter cable to link card to bus. Software available in Ada or Quick Basic language.

  3. Bridging genetic networks and queueing theory

    NASA Astrophysics Data System (ADS)

    Arazi, Arnon; Ben-Jacob, Eshel; Yechiali, Uri

    2004-02-01

    One of the main challenges facing biology today is the understanding of the joint action of genes, proteins and RNA molecules, interwoven in intricate interdependencies commonly known as genetic networks. To this end, several mathematical approaches have been introduced to date. In addition to developing the analytical tools required for this task anew, one can utilize knowledge found in existing disciplines, specializing in the representation and analysis of systems featuring similar aspects. We suggest queueing theory as a possible source of such knowledge. This discipline, which focuses on the study of workloads forming in a variety of scenarios, offers an assortment of tools allowing for the derivation of the statistical properties of the inspected systems. We argue that a proper adaptation of modeling techniques and analytical methods used in queueing theory can contribute to the study of genetic regulatory networks. This is demonstrated by presenting a queueing-inspired model of a genetic network of arbitrary size and structure, for which the probability distribution function is derived. This model is further applied to the description of the lac operon regulation mechanism. In addition, we discuss the possible benefits stemming for queueing theory from the interdisciplinary dialogue with molecular biology-in particular, the incorporation of various dynamical behaviours into queueing networks.

  4. School Bus Facilities.

    ERIC Educational Resources Information Center

    Stanford Univ., CA. School Planning Lab.

    A summary is presented of a study to determine the building needs of the school transportation operation and to suggest possible uses of aluminum. The report outlines the magnitude of school transportation systems as an indication of buildings necessary to house and maintain equipment. The types of areas needed to fulfill the bus housing and…

  5. Bully on the Bus

    ERIC Educational Resources Information Center

    Harrison, Mary M.

    2005-01-01

    Across the U.S., more than 24 million students begin and end their school days on buses. In most cases, the driver is the only adult on board. To transport students safely, the driver must watch the road, not the riders, during most of the trip. Although bus drivers have mirrors and usually see fights, they can easily miss pushing, shoving, and…

  6. Augmented thermal bus

    NASA Technical Reports Server (NTRS)

    Schrage, Dean S. (Inventor)

    1993-01-01

    The present invention is directed to an augmented thermal bus. In the present design a plurity of thermo-electric heat pumps are used to couple a source plate to a sink plate. Each heat pump is individually controlled by a model based controller. The controller coordinates the heat pump to maintain isothermality in the source.

  7. SCHOOL BUS GARAGE.

    ERIC Educational Resources Information Center

    PALLIDINO, STEVE; STRIPLING, CHARLES W.

    COUNTY BOARDS, COUNTY SUPERINTENDENTS, SCHOOL PERSONNEL, AND ARCHITECTS PLANNING BUS GARAGE FACILITIES WILL FIND THIS PUBLICATION USEFUL. DECISIONS NEED TO BE MADE IN REGARD TO WHO WILL USE THE GARAGE, WHAT PURPOSE IT SHOULD SERVE, AND WHAT KIND OF SPACES ARE NEEDED. SITE SELECTION FACTORS TO BE CONSIDERED ARE LOCATION, PARKING SPACE, MANEUVERING…

  8. Augmented Thermal Bus

    NASA Technical Reports Server (NTRS)

    Schrage, Dean S. (Inventor)

    1996-01-01

    The present invention is directed to an augmented thermal bus. In the present design a plurality of thermo-electric heat pumps are used to couple a source plate to a sink plate. Each heat pump is individually controlled by a model based controller. The controller coordinates the heat pumps to maintain isothermality in the source.

  9. Product-form solution techniques for the performance analysis of multiple-bus multiprocessor systems with nonuniform memory references

    SciTech Connect

    Chiola, G.; Marsan, M.A.; Balbo, G.

    1988-05-01

    Recursive relations are derived for the exact computation of the steady-state probability distribution of some queueing models with passive resources that can be used to analyze the performance of multiple-bus multiprocessor system architectures. The most general case that was shown to admit a product-form solution is described, and a recursive solution is obtained considering different processor access rates, different memory selection probabilities, and an FCFS bus scheduling policy. Several simpler cases allowing easier model solutions are also considered. Numerical evaluations of large computing systems with nonuniform memory references show the usefulness of the results.

  10. Bus bar copper losses computation

    NASA Astrophysics Data System (ADS)

    Besacier, M.; Guichon, J. M.; Schanen, J. L.; Roudet, J.

    2003-07-01

    This paper describes how to forecast copper losses in a bus bar, composed of thin copper layers and several access points. The main difficulties are, first to determine current path and associated electrical characteristics, and second to propose electrical equivalent circuits of the bus bar, allowing copper losses representation. For bus bar electrical modeling, the choice of an integral method, PEEC method, is justified. Then, several equivalent circuits are proposed and their validity for copper losses computation discussed.

  11. Euro Data Bus

    SciTech Connect

    Engel, H.E.; Hall, J.R. II; Schrock, C.B.

    1995-12-31

    With the disintegration of the Soviet Union and the opening of the Iron Curtain, a downsizing of the Defense Establishment in the West is occurring, causing industry to look for opportunities where technology used for military applications can be applied to meet former East Block countries. Among these requirements has been the urgent desire of the people in former East Block countries for access to Western media which had been denied them, and has led to numerous opportunities for the implementation of Cable Television (CATV) systems. In addition, there are also requirements for utility metering for electricity, gas, water, heat, etc. which had previously been provided to the population by the Government at little or no cost. EWT of Augsburg, Germany, previously a subcontractor to ASEC on military security system projects, who has a subsidiary, TSS, which is a prominent CATV systems house, requested ASEC to provide a system which can provide utility meter reading and other control and monitoring services utilizing CATV. Working with CableBus Systems Corporation, a CATV data communications supplier and various utility meter manufacturers, ASEC, as the System Integrator, has developed a utilities monitoring system. This system. in cooperation with EWT, is being marketed and sold in Europe as EURO DATA BUS. This paper describes EURO DATA BUS and its applications, as well as the actual system designs for two pilot applications. One system is oriented at Utility Meter Reading and Demand side Management primarily, but will also be used to demonstrate other system capabilities such as security and fire alarm monitoring, etc. The design is therefore quite straightforward and {open_quotes}standard{close_quotes}. The second system has more of an industrial orientation and involves the monitoring and load control for a Municipal Electric Utility. While well within the capabilities of the system to accomplish, a more customized design was required to meet these requirements.

  12. 75 FR 23843 - Discretionary Bus and Bus Facilities Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-04

    ...-investment needs. FTA's April 2009 Rail Modernization Study estimated a combined $50 billion repair and replacement backlog in the bus and rail systems of the seven oldest and largest U.S. transit agencies. The... needing repair or replacement, the FTA proposed a $2.9 billion Bus and Rail State of Good Repair...

  13. Tennessee Minimum School Bus Standards.

    ERIC Educational Resources Information Center

    Tennessee State Board of Education, 2004

    2004-01-01

    The School Bus Specifications and Procedures adopted by the 2000 National Conference on School Transportation and the Federal Motor Vehicle Safety Standards (FMVSS) were used as guides by the Tennessee State Board of Education Pupil Transportation Advisory Committee in developing the revised minimum specifications for school bus chassis and school…

  14. Cost performance satellite design using queueing theory

    NASA Technical Reports Server (NTRS)

    Hein, G. F.

    1975-01-01

    The Poisson arrival model was used to determine the effects of limiting the number of channels for a disaster warning satellite. State probabilities and delay probabilities were estimated for several values of the number of channels (C) for arrival and service rates obtained from disaster warnings issued by the National Weather Service. The results predicted by the queueing model were compared with the results of a digital computer simulation.

  15. Engineering queues in construction and mining

    SciTech Connect

    Carmichael, D.G.

    1987-01-01

    This book models that reflect the stochastic or variable nature of construction and mining operations. The treatment of queueing theory applied to these operations presents conceptual and quantitative models applicable to both planning and management. The approach integrates operations research, management science, and systems engineering, enabling practitioners in the field to formulate and describe in general terms the characteristic quantities of construction and mining operations.

  16. The Average Velocity in a Queue

    ERIC Educational Resources Information Center

    Frette, Vidar

    2009-01-01

    A number of cars drive along a narrow road that does not allow overtaking. Each driver has a certain maximum speed at which he or she will drive if alone on the road. As a result of slower cars ahead, many cars are forced to drive at speeds lower than their maximum ones. The average velocity in the queue offers a non-trivial example of a mean

  17. The Average Velocity in a Queue

    ERIC Educational Resources Information Center

    Frette, Vidar

    2009-01-01

    A number of cars drive along a narrow road that does not allow overtaking. Each driver has a certain maximum speed at which he or she will drive if alone on the road. As a result of slower cars ahead, many cars are forced to drive at speeds lower than their maximum ones. The average velocity in the queue offers a non-trivial example of a mean…

  18. Data bus system development program

    NASA Technical Reports Server (NTRS)

    Harrison, J. S. J.

    1973-01-01

    Two data bus systems were designed fabricated, Data Bus System I and Data Bus System II. The technical features of the delivered hardware include the following: (1) 5 MHz selfclocking data bus; (2) bidirectional communications utilizing Manchester Code at data rates in excess of 20,000 words per second; (3) utilization of MSI COS/MOS technology (4) probability of accepting an erroneous data bit less than 1 in 10 to the 25th power (5) low power consumption (50 to 1 reduction in quiescent current over P/MOS) (6) compatibility with projected high density packaging. Three distinct types of data bus remote terminals were developed: the subsystem interface unit, the combination of an electronic interface unit and a standard interface unit-serial, and an SIU/Preprocessor.

  19. Control of a heterogeneous two-server exponential queueing system

    NASA Technical Reports Server (NTRS)

    Larsen, R. L.; Agrawala, A. K.

    1983-01-01

    A dynamic control policy known as 'threshold queueing' is defined for scheduling customers from a Poisson source on a set of two exponential servers with dissimilar service rates. The slower server is invoked in response to instantaneous system loading as measured by the length of the queue of waiting customers. In a threshold queueing policy, a specific queue length is identified as a 'threshold,' beyond which the slower server is invoked. The slower server remains busy until it completes service on a customer and the queue length is less than its invocation threshold. Markov chain analysis is employed to analyze the performance of the threshold queueing policy and to develop optimality criteria. It is shown that probabilistic control is suboptimal to minimize the mean number of customers in the system. An approximation to the optimum policy is analyzed which is computationally simple and suffices for most operational applications.

  20. Hybrid Electric Transit Bus

    NASA Technical Reports Server (NTRS)

    Viterna, Larry A.

    1997-01-01

    A government, industry, and university cooperative is developing an advanced hybrid electric city transit bus. Goals of this effort include doubling the fuel economy compared to current buses and reducing emissions to one-tenth of current EPA standards. Unique aspects of the vehicle's power system include the use of ultra-capacitors as an energy storage system, and a planned natural gas fueled turbogenerator developed from a small jet engine. Power from both the generator and energy storage system is provided to a variable speed electric motor attached to the rear axle. At over 15000 kg gross weight, this is the largest vehicle of its kind ever built using ultra-capacitor energy storage. This paper describes the overall power system architecture, the evolution of the control strategy, and its performance over industry standard drive cycles.

  1. Reducing transit bus emissions: Alternative fuels or traffic operations?

    NASA Astrophysics Data System (ADS)

    Alam, Ahsan; Hatzopoulou, Marianne

    2014-06-01

    In this study, we simulated the operations and greenhouse gas (GHG) emissions of transit buses along a busy corridor and quantified the effects of two different fuels (conventional diesel and compressed natural gas) as well as a set of driving conditions on emissions. Results indicate that compressed natural gas (CNG) reduces GHG emissions by 8-12% compared to conventional diesel, this reduction could increase to 16% with high levels of traffic congestion. However, the benefits of switching from conventional diesel to CNG are less apparent when the road network is uncongested. We also investigated the effects of bus operations on emissions by applying several strategies such as transit signal priority (TSP), queue jumper lanes, and relocation of bus stops. Results show that in congested conditions, TSP alone can reduce GHG emissions by 14% and when combined with improved technology; a reduction of 23% is achieved. The reduction benefits are even more apparent when other transit operational improvements are combined with TSP. Finally a sensitivity analysis was performed to investigate the effect of operational improvements on emissions under varying levels of network congestion. We observe that under “extreme congestion”, the benefits of TSP decrease.

  2. High-Speed Ring Bus

    NASA Technical Reports Server (NTRS)

    Wysocky, Terry; Kopf, Edward, Jr.; Katanyoutananti, Sunant; Steiner, Carl; Balian, Harry

    2010-01-01

    The high-speed ring bus at the Jet Propulsion Laboratory (JPL) allows for future growth trends in spacecraft seen with future scientific missions. This innovation constitutes an enhancement of the 1393 bus as documented in the Institute of Electrical and Electronics Engineers (IEEE) 1393-1999 standard for a spaceborne fiber-optic data bus. It allows for high-bandwidth and time synchronization of all nodes on the ring. The JPL ring bus allows for interconnection of active units with autonomous operation and increased fault handling at high bandwidths. It minimizes the flight software interface with an intelligent physical layer design that has few states to manage as well as simplified testability. The design will soon be documented in the AS-1393 standard (Serial Hi-Rel Ring Network for Aerospace Applications). The framework is designed for "Class A" spacecraft operation and provides redundant data paths. It is based on "fault containment regions" and "redundant functional regions (RFR)" and has a method for allocating cables that completely supports the redundancy in spacecraft design, allowing for a complete RFR to fail. This design reduces the mass of the bus by incorporating both the Control Unit and the Data Unit in the same hardware. The standard uses ATM (asynchronous transfer mode) packets, standardized by ITU-T, ANSI, ETSI, and the ATM Forum. The IEEE-1393 standard uses the UNI form of the packet and provides no protection for the data portion of the cell. The JPL design adds optional formatting to this data portion. This design extends fault protection beyond that of the interconnect. This includes adding protection to the data portion that is contained within the Bus Interface Units (BIUs) and by adding to the signal interface between the Data Host and the JPL 1393 Ring Bus. Data transfer on the ring bus does not involve a master or initiator. Following bus protocol, any BIU may transmit data on the ring whenever it has data received from its host. There is no centralized arbitration or bus granting. The JPL design provides for autonomous synchronization of the nodes on the ring bus. An address-synchronous latency adjust buffer (LAB) has been designed that cannot get out of synchronization and needs no external input. Also, a priority-driven cable selection behavior has been programmed into each unit on the ring bus. This makes the bus able to connect itself up, according to a maximum redundancy priority system, without the need for computer intervention at startup. Switching around a failed or switched-off unit is also autonomous. The JPL bus provides a map of all the active units for the host computer to read and use for fault management. With regard to timing, this enhanced bus recognizes coordinated timing on a spacecraft as critical and addresses this with a single source of absolute and relative time, which is broadcast to all units on the bus with synchronization maintained to the tens of nanoseconds. Each BIU consists of up to five programmable triggers, which may be programmed for synchronization of events within the spacecraft of instrument. All JPL-formatted data transmitted on the ring bus are automatically time-stamped.

  3. Available Alternative Fuel School Bus Products--2004

    SciTech Connect

    Not Available

    2004-04-01

    This 4-page Clean Cities fact sheet provides a list of the currently available (and soon to be available) model year 2004 alternative fuel school bus and school bus engine products. It includes information from Blue Bird Corporation, Collins Bus Corporation, Corbeil Bus, Ford Motor Company, General Motors Corporation, Thomas Built Buses, Inc., Clean Air Partners, Cummins Westport, and Deere & Company.

  4. 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)

  5. Ring Buffered Network Bus

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This report describes the research effort to demonstrate the integration of a data sharing technology, Ring Buffered Network Bus, in development by Dryden Flight Research Center, with an engine simulation application, the Java Gas Turbine Simulator, in development at the University of Toledo under a grant from the Glenn Research Center. The objective of this task was to examine the application of the RBNB technologies as a key component in the data sharing, health monitoring and system wide modeling elements of the NASA Aviation Safety Program (AVSP) [Golding, 1997]. System-wide monitoring and modeling of aircraft and air safety systems will require access to all data sources which are relative factors when monitoring or modeling the national airspace such as radar, weather, aircraft performance, engine performance, schedule and planning, airport configuration, flight operations, etc. The data sharing portion of the overall AVSP program is responsible for providing the hardware and software architecture to access and distribute data, including real-time flight operations data, among all of the AVSP elements. The integration of an engine code capable of numerically "flying" through recorded flight paths and weather data using a software tool that allows for distributed access of data to this engine code demonstrates initial steps toward building a system capable of monitoring and modeling the National Airspace.

  6. Queues with Dropping Functions and General Arrival Processes.

    PubMed

    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

  7. 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

  8. Weighted scheduling based on queue length and delay for AOPS

    NASA Astrophysics Data System (ADS)

    Chen, Qianbin; Pang, Junyu; Liu, Huanlin

    2007-11-01

    Packet scheduling plays an important role in the asynchronous optical switched networks for node performance. A weighted scheduling algorithm based on the queue length associated with waiting delay was proposed to solve the packet starvation of queue length weighted scheduling for the length variable OPS. The contention is resolved either in wavelength domain by limited range wavelength converters and in time domain by fiber delay lines. The work has contributed with a very powerful scheduling mechanism which reduces resource contention at the asynchronous OPS core nodes and guarantees a reasonable packet delay thanks to its weighted scheduling algorithm based on queue length and waiting delay for variable length OPS network. The scheduler calculates every input ports with N×K virtual output queue (VOQ) weight and schedules the maximal weight queue packets to available output channel. The analysis and simulation results show that the proposed scheduling has high throughput and low packet loss ratio.

  9. Critical behavior of the exclusive queueing process

    NASA Astrophysics Data System (ADS)

    Arita, Chikashi; Schadschneider, Andreas

    2013-11-01

    The exclusive queueing process (EQP) is a generalization of the classical M/M/1 queue. It is equivalent to a totally asymmetric exclusion process (TASEP) of varying length. Here we consider two discrete-time versions of the EQP with parallel and backward-sequential update rules. The phase diagram (with respect to the arrival probability α and the service probability β) is divided into two phases corresponding to divergence and convergence of the system length. We investigate the behavior on the critical line separating these phases. For both update rules, we find diffusive behavior for small service probability (\\beta < \\beta_c) . However, for \\beta>\\beta_c it becomes sub-diffusive and nonuniversal: the critical exponents characterizing the divergence of the system length and the number of customers are found to depend on the update rule. For the backward-update case, they also depend on the hopping parameter p, and remain finite when p is large, indicating a first-order transition.

  10. Dynamical analysis of the exclusive queueing process

    NASA Astrophysics Data System (ADS)

    Arita, Chikashi; Schadschneider, Andreas

    2011-05-01

    Recently, the stationary state of a parallel-update totally asymmetric simple exclusion process with varying system length, which can be regarded as a queueing process with excluded-volume effect (exclusive queueing process), was obtained [C Arita and D Yanagisawa, J. Stat. Phys.JSTPBS0022-471510.1007/s10955-010-0075-9 141, 829 (2010)]. In this paper, we analyze the dynamical properties of the number of particles and the position of the last particle (the system length) , using an analytical method (generating function technique) as well as a phenomenological description based on domain-wall dynamics and Monte Carlo simulations. The system exhibits two phases corresponding to linear convergence or divergence of and . These phases can both further be subdivided into high-density and maximal-current subphases. The predictions of the domain-wall theory are found to be in very good agreement quantitively with results from Monte Carlo simulations in the convergent phase. On the other hand, in the divergent phase, only the prediction for agrees with simulations.

  11. Forecast analysis of optical waveguide bus performance

    NASA Technical Reports Server (NTRS)

    Ledesma, R.; Rourke, M. D.

    1979-01-01

    Elements to be considered in the design of a data bus include: architecture; data rate; modulation, encoding, detection; power distribution requirements; protocol, work structure; bus reliability, maintainability; interterminal transmission medium; cost; and others specific to application. Fiber- optic data bus considerations for a 32 port transmissive star architecture, are discussed in a tutorial format. General optical-waveguide bus concepts, are reviewed. The electrical and optical performance of a 32 port transmissive star bus, and the effects of temperature on the performance of optical-waveguide buses are examined. A bibliography of pertinent references and the bus receiver test results are included.

  12. Aids to School Bus Design

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Navistar International Transportation Corporation, Chicago, IL, used three separate NASA-developed technologies in the design and testing of their 3000 Series Bus Chassis which was developed expressly for school bus applications. For structural analysis, they used the MSC/NASTRAN program which mathematically analyzes a design and predicts how it will hold up under stress. They also used the SPATE 9000 system for non-contact measurement of stress, load transfer mechanisms, detection of hidden flaws, and monitoring structural changes during fatigue testing. SPATE 9000 was based on infrared stress measurement technology developed by Langley Research Center. They also employed the Wyle Ride Quality Meter, which was developed by Langley to aid in passenger aircraft design by providing an accurate measurement of ride vibration and sound level. These numbers translate into a subjective discomfort level index. These technologies contribute to the company's 45-48 percent share of the school bus chassis market.

  13. An object oriented software bus

    SciTech Connect

    McGirt, F.; Wilkerson, J.F.

    1995-12-31

    This paper describes a new approach to development of software for highly integrated software-hardware systems such as used for data acquisition and control. This approach, called the Object Oriented Software Bus (OSB), is a way to develop software according to a common specification similar to the way interface hardware has been developed since the advent of bus structures for minicomputers and microcomputers. Key concept of the OSB is extension of the common use of objects to support user interface and data analysis functions to the development of software objects that directly correspond to real- world hardware interfaces and modules.

  14. Some Questions to Ask about Your School Bus Program.

    ERIC Educational Resources Information Center

    Balousek, Marvin

    1980-01-01

    Questions based on observations of a Chicago (Illinois) school bus program deal with driver capability, procedures for bus evacuation in an emergency, bus comfort for passengers, safety, fuel efficiency, and creative use of students' bus time. (MLF)

  15. 75 FR 5847 - Section 5309 Bus and Bus Facilities Livability Initiative and Urban Circulator Program Grants

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-04

    ... Federal Transit Administration Section 5309 Bus and Bus Facilities Livability Initiative and Urban... Application Deadline for the Bus and Bus Facilities and Urban Circulator Livability Initiative Programs... (SAFETEA-LU), Public Law 109-59, August 10, 2005. The Urban Circulator Program is funded using $130...

  16. Opportunistic Channel Scheduling for Ad Hoc Networks with Queue Stability

    NASA Astrophysics Data System (ADS)

    Dong, Lei; Wang, Yongchao

    2015-03-01

    In this paper, a distributed opportunistic channel access strategy in ad hoc network is proposed. We consider the multiple sources contend for the transmission opportunity, the winner source decides to transmit or restart contention based on the current channel condition. Owing to real data assumption at all links, the decision still needs to consider the stability of the queues. We formulate the channel opportunistic scheduling as a constrained optimization problem which maximizes the system average throughput with the constraints that the queues of all links are stable. The proposed optimization model is solved by Lyapunov stability in queueing theory. The successive channel access problem is decoupled into single optimal stopping problem at every frame and solved with Lyapunov algorithm. The threshold for every frame is different, and it is derived based on the instantaneous queue information. Finally, computer simulations are conducted to demonstrate the validity of the proposed strategy.

  17. Behavior of queues at signalized intersections in heavy traffic

    NASA Technical Reports Server (NTRS)

    Posner, E. C.; Rodemich, E. R.

    1976-01-01

    This paper derives the asymptotic behavior of traffic queues at signalized intersections when the excess of departure capacity over arrivals approaches zero from above. The most interesting result is that the distribution of queue length approaches a negative exponential, with fewer restrictive assumptions than hitherto known. The main improvement results from more precise use of a combinatorial lemma of Spitzer, giving the maximum of the partial sums of a sequence of independent identically distributed random variables, plus some specific constructive probability calculations, many of them involving the Fourier transform. New results are presented on the probability that the queue be below a fixed bound and/or on the probability that the queue be empty. Applications to on-line estimators for real-time traffic control are suggested.

  18. A Report on Stochastic Fairness Queueing (SFQ) Experiments

    NASA Technical Reports Server (NTRS)

    Denny, Barbara A.

    1993-01-01

    SRI International (SRI) has developed an improved queueing algorithm, known as Stochastic Fairness Queueing (SFQ), for best-effort traffic (i.e., traffic that does not require any guaranteed service). SFQ is a probablistic variant of strict fair queueing where instead of a single queue being allocated per flow, a fixed number of queues are used and a hash function maps the IP source and destination to a particular queue. A seed to the hash function is also perturbed occasionally to help distribute the flows amongst different queues when more than one flow maps to the same queue during the lifetime of the flow. SFQ provides 'fair' access by trying to ensure that each flow from source to destination host obtains equal access to the available bandwidth. This report covers a series of experiments performed on DARTnet evaluating the behavior and performance of SFQ against a FIFO queueing discipline. These experiments were designed to show SFQ's advantages and performance, and include tests demonstrating: Fair utilization of available resources; Starvation prevention; Graceful degradation under overload conditions; and Resource usage. In general, the experiments do show that SFQ is better than FIFO queueing at allocating bandwidth equally among a set of flows. SFQ also prevents a stream from dominating the available bandwidth, which seems to be a tendency with FIFO queueing (i.e., if a flow demands more than its share of the available bandwidth, with FIFO queueing that stream receives a disproportionate amount when compared to flows demanding less than their share). Furthermore, SFQ seems to reward 'nice' users of the network by providing a lower variance in delay and more throughput when their resource demand is less than their available share. Both SFQ and FIFO queueing seem to degrade fairly well as the network becomes saturated and to recover well as the network becomes less congested. Not unexpectedly, FIFO queueing is a little more efficient than SFQ-the delays are less and the throughput slightly higher because SFQ requires more processing. However, the performance difference between the two queueing disciplines is relatively small. However, the experiments do point out some interesting behavior. FIFO queueing can behave better than SFQ with seed perturbation. We recommend further evaluation of the hash function and the seed perturbation technique. There are probably weaknesses in their current selection that cause this unexpected behavior. SFQ also seems to possess good scaling properties. To verify this, more experiments with a larger number of streams from more hosts need to be executed and examined, including the staggered introduction of streams. Staggering the streams may prove important, because graphs in the degradation experiment revealed some unexpected increases and decreases in throughput, which should be examined. This may again be due to the interaction of the hash function with the seed perturbation but it may also be related to some other unknown problem.

  19. Optimal Routing in General Finite Multi-Server Queueing Networks

    PubMed Central

    van Woensel, Tom; Cruz, Frederico R. B.

    2014-01-01

    The design of general finite multi-server queueing networks is a challenging problem that arises in many real-life situations, including computer networks, manufacturing systems, and telecommunication networks. In this paper, we examine the optimal routing problem in arbitrary configured acyclic queueing networks. The performance of the finite queueing network is evaluated with a known approximate performance evaluation method and the optimization is done by means of a heuristics based on the Powell algorithm. The proposed methodology is then applied to determine the optimal routing probability vector that maximizes the throughput of the queueing network. We show numerical results for some networks to quantify the quality of the routing vector approximations obtained. PMID:25010660

  20. School Bus Accidents and Driver Age.

    ERIC Educational Resources Information Center

    McMichael, Judith

    The study examines the rates and types of school bus accidents according to the age of the school bus driver. Accident rates in North Carolina for the school year 1971-72 were analyzed using three sources of data: accident reports, driver and mileage data, and questionnaires administered to a sample of school bus drivers. Data were obtained on…

  1. The NASA bus communications listening device software

    NASA Technical Reports Server (NTRS)

    Allen, M. A.

    1979-01-01

    The development of the bus listener is presented. Special software was developed to control the 'bus interface units' (BIU) connecting each of these devices to a communications cable to form the bus communication network. The code used in the BTU is described.

  2. "Don't Miss the Bus!"

    ERIC Educational Resources Information Center

    Lieberth, Jane A.

    1999-01-01

    Presents observations from the director of the National Association of Pupil Transportation concerning school bus safety, seat belts, and the state of the $15-billion school transportation industry. Increasing student use of bus transportation and delivering the school bus safety message to all concerned are addressed. (GR)

  3. 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. PMID:10768439

  4. Pybus -- A Python Software Bus

    SciTech Connect

    Lavrijsen, Wim T.L.P.

    2004-10-14

    A software bus, just like its hardware equivalent, allows for the discovery, installation, configuration, loading, unloading, and run-time replacement of software components, as well as channeling of inter-component communication. Python, a popular open-source programming language, encourages a modular design on software written in it, but it offers little or no component functionality. However, the language and its interpreter provide sufficient hooks to implement a thin, integral layer of component support. This functionality can be presented to the developer in the form of a module, making it very easy to use. This paper describes a Pythonmodule, PyBus, with which the concept of a ''software bus'' can be realized in Python. It demonstrates, within the context of the ATLAS software framework Athena, how PyBus can be used for the installation and (run-time) configuration of software, not necessarily Python modules, from a Python application in a way that is transparent to the end-user.

  5. HERMES travels by CAN bus

    NASA Astrophysics Data System (ADS)

    Waller, Lewis G.; Shortridge, Keith; Farrell, Tony J.; Vuong, Minh; Muller, Rolf; Sheinis, Andrew I.

    2014-07-01

    The new HERMES spectrograph represents the first foray by AAO into the use of commercial off-the-shelf industrial field bus technology for instrument control, and we regard the final system, with its relatively simple wiring requirements, as a great success. However, both software and hardware teams had to work together to solve a number of problems integrating the chosen CANopen/CAN bus system into our normal observing systems. A Linux system running in an industrial PC chassis ran the HERMES control software, using a PCI CAN bus interface connected to a number of distributed CANopen/CAN bus I/O devices and servo amplifiers. In the main, the servo amplifiers performed impressively, although some experimentation with homing algorithms was required, and we hit a significant hurdle when we discovered that we needed to disable some of the encoders used during observations; we learned a lot about how servo amplifiers respond when their encoders are turned off, and about how encoders react to losing power. The software was based around a commercial CANopen library from Copley Controls. Early worries about how this heavily multithreaded library would work with our standard data acquisition system led to the development of a very low-level CANopen software simulator to verify the design. This also enabled the software group to develop and test almost all the control software well in advance of the construction of the hardware. In the end, the instrument went from initial installation at the telescope to successful commissioning remarkably smoothly.

  6. Low-inductance bus lines

    NASA Technical Reports Server (NTRS)

    Kernick, A.

    1977-01-01

    Laminated bus strips and bifilar litz cable connectors for high-power rectifiers, thrisistors, and transistors provide low inductance and eliminate electromagnetic interference in high-power circuits. These techniques offer significant cost advantages because of ease of assembly and consistent high quality of product. Effectiveness makes general usage in static power conversion likely.

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

    DOEpatents

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

    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.

  8. Efficiency and robustness of different bus network designs

    NASA Astrophysics Data System (ADS)

    Pang, John Zhen Fu; Bin Othman, Nasri; Ng, Keng Meng; Monterola, Christopher

    2015-07-01

    We compare the efficiencies and robustness of four transport networks that can be possibly formed as a result of deliberate city planning. The networks are constructed based on their spatial resemblance to the cities of Manhattan (lattice), Sudan (random), Beijing (single-blob) and Greater Cairo (dual-blob). For a given type, a genetic algorithm is employed to obtain an optimized set of the bus routes. We then simulate how commuter travels using Yen's algorithms for k shortest paths on an adjacency matrix. The cost of traveling such as walking between stations is captured by varying the weighted sums of matrices. We also consider the number of transfers a posteriori by looking at the computed shortest paths. With consideration to distances via radius of gyration, redundancies of travel and number of bus transfers, our simulations indicate that random and dual-blob are more efficient than single-blob and lattice networks. Moreover, dual-blob type is least robust when node removals are targeted but is most resilient when node failures are random. The work hopes to guide and provide technical perspectives on how geospatial distribution of a city limits the optimality of transport designs.

  9. Preliminary Flight Results of the Microelectronics and Photonics Test Bed: NASA DR1773 Fiber Optic Data Bus Experiment

    NASA Technical Reports Server (NTRS)

    Jackson, George L.; LaBel, Kenneth A.; Marshall, Cheryl; Barth, Janet; Seidleck, Christina; Marshall, Paul

    1998-01-01

    NASA Goddard Spare Flight Center's (GSFC) Dual Rate 1773 (DR1773) Experiment on the Microelectronic and Photonic Test Bed (MPTB) has provided valuable information on the performance of the AS 1773 fiber optic data bus in the space radiation environment. Correlation of preliminary experiment data to ground based radiation test results show the AS 1773 bus is employable in future spacecraft applications requiring radiation tolerant communication links.

  10. Analysis of robustness of urban bus network

    NASA Astrophysics Data System (ADS)

    Tao, Ren; Yi-Fan, Wang; Miao-Miao, Liu; Yan-Jie, Xu

    2016-02-01

    In this paper, the invulnerability and cascade failures are discussed for the urban bus network. Firstly, three static models(bus stop network, bus transfer network, and bus line network) are used to analyse the structure and invulnerability of urban bus network in order to understand the features of bus network comprehensively. Secondly, a new way is proposed to study the invulnerability of urban bus network by modelling two layered networks, i.e., the bus stop-line network and the bus line-transfer network and then the interactions between different models are analysed. Finally, by modelling a new layered network which can reflect the dynamic passenger flows, the cascade failures are discussed. Then a new load redistribution method is proposed to study the robustness of dynamic traffic. In this paper, the bus network of Shenyang City which is one of the biggest cities in China, is taken as a simulation example. In addition, some suggestions are given to improve the urban bus network and provide emergency strategies when traffic congestion occurs according to the numerical simulation results. Project supported by the National Natural Science Foundation of China (Grant Nos. 61473073, 61374178, 61104074, and 61203329), the Fundamental Research Funds for the Central Universities (Grant Nos. N130417006, L1517004), and the Program for Liaoning Excellent Talents in University (Grant No. LJQ2014028).

  11. Electrical system architecture having high voltage bus

    DOEpatents

    Hoff, Brian Douglas; Akasam, Sivaprasad

    2011-03-22

    An electrical system architecture is disclosed. The architecture has a power source configured to generate a first power, and a first bus configured to receive the first power from the power source. The architecture also has a converter configured to receive the first power from the first bus and convert the first power to a second power, wherein a voltage of the second power is greater than a voltage of the first power, and a second bus configured to receive the second power from the converter. The architecture further has a power storage device configured to receive the second power from the second bus and deliver the second power to the second bus, a propulsion motor configured to receive the second power from the second bus, and an accessory motor configured to receive the second power from the second bus.

  12. Ethics in radiology: wait lists queue jumping.

    PubMed

    Cunningham, Natalie; Reid, Lynette; MacSwain, Sarah; Clarke, James R

    2013-08-01

    Education in ethics is a requirement for all Royal College residency training programs as laid out in the General Standards of Accreditation for residency programs in Canada. The ethical challenges that face radiologists in clinical practice are often different from those that face other physicians, because the nature of the physician-patient interaction is unlike that of many other specialties. Ethics education for radiologists and radiology residents will benefit from the development of teaching materials and resources that focus on the issues that are specific to the specialty. This article is intended to serve as an educational resource for radiology training programs to facilitate teaching ethics to residents and also as a continuing medical education resource for practicing radiologists. In an environment of limited health care resources, radiologists are frequently asked to expedite imaging studies for patients and, in some respects, act as gatekeepers for specialty care. The issues of wait lists, queue jumping, and balancing the needs of individuals and society are explored from the perspective of a radiologist. PMID:22867960

  13. Unslotted 1- and p(i)-persistent CSMA-CD protocols for fiber optic bus networks

    NASA Astrophysics Data System (ADS)

    Yoon, Chong Ho; Un, Chong Kwan

    1994-02-01

    We analyze the performance of the unslotted 1-persistent carrier sense multiple access with collision detection (CSMA-CD) protocol for fiber optic bus networks with a finite number of stations M, each of which has an infinite storage buffer for storing packets with its length fixed or exponentially distributed. Treating the bus network as an M-class priority queueing system with a preemptive-repeat-identical retransmission strategy, we show numerically that this 1-persistent retransmission strategy provides better delay-throughput performance than the non-persistent one. To satisfy the fairness of equal delays among stations in the bus network, we next present the unslotted p(sub i)-persistent CSMA-CD protocol. Under this protocol, the first packet arriving at station i is forced to enter into the backoff procedure with the probability of (1 - p(sub i)). After backoffs, transmission begins until the station becomes empty. We determine the persistent probability p(sub i) and show that the delay-throughput performance of the p(sub i)-persistent strategy is better than that of the 1-persistent one, and further it is robust for any packet lengths. Simulation results are presented to verify the analytical results.

  14. PinBus Interface Design

    SciTech Connect

    Hammerstrom, Donald J.; Adgerson, Jewel D.; Sastry, Chellury; Pratt, Richard M.; Pratt, Robert G.

    2009-12-30

    On behalf of the U.S. Department of Energy, PNNL has explored and expanded upon a simple control interface that might have merit for the inexpensive communication of smart grid operational objectives (demand response, for example) to small electric end-use devices and appliances. The approach relies on bi-directional communication via the electrical voltage states of from one to eight shared interconnection pins. The name PinBus has been suggested and adopted for the proposed interface protocol. The protocol is defined through the presentation of state diagrams and the pins’ functional definitions. Both simulations and laboratory demonstrations are being conducted to demonstrate the elegance and power of the suggested approach. PinBus supports a very high degree of interoperability across its interfaces, allowing innumerable pairings of devices and communication protocols and supporting the practice of practically any smart grid use case.

  15. A new vehicle data bus architecture and IVIS evaluation platform for ITS modulus

    SciTech Connect

    Spelt, P.F.; Kirson, A.M.; Scott, S.

    1998-12-31

    An increasing number of ITS-related after-market systems present a set of in-vehicle installation and use problems relatively unique in the history of automobile use. Many automobile manufacturers would like to offer these new state of the art devices to customers, but are hampered by the current design cycle of new cars. While auto manufacturers are indeed using multiplex buses (the automotive equivalent of a computer local area network), problems remain because manufacturers are not converging on a single bus standard. This paper presents a new dual-bus architecture to address these problems, with an In-Vehicle Information System (IVIS) research platform on which the principles embodied in the ITS Data Bus architecture can be evaluated. The dual-bus architecture has been embodied in a proposed SAE standard, with a ratification vote in December, 1996. The architecture and a reference model for the interfaces and protocols of the new bus are presented and described. The goals of the ITS Data Bus are to be inexpensive and easy to install, and to provide for safe and secure functioning. These high-level goals are embodied in the proposed standard. The IVIS Development Platform comprises a number of personal computers linked via ethernet LAN, with a high-end PC serving as the IVIS computer. In this LAN, actual devices can be inserted in place of the original PC which emulated them. This platform will serve as the development and test bed for an ITS Data Bus Conformity Test, the SAE standard for which has also been developed.

  16. Characteristics of the Unexpected Message Queue of MPI applications

    SciTech Connect

    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 the 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.

  17. Simple queueing model applied to the city of Portland

    SciTech Connect

    Simon, P.M.; Nagel, K. |

    1998-07-31

    The authors present a simple traffic micro-simulation model that models the effects of capacity cut-off, i.e. the effect of queue built-up when demand is exceeding capacity, and queue spillback, i.e. the effect that queues can spill back across intersections when a congested link is filled up. They derive the model`s fundamental diagrams and explain it. The simulation is used to simulate traffic on the emme/2 network of the Portland (Oregon) metropolitan region (20,000 links). Demand is generated by a simplified home-to-work assignment which generates about half a million trips for the AM peak. Route assignment is done by iterative feedback between micro-simulation and router. Relaxation of the route assignment for the above problem can be achieved within about half a day of computing time on a desktop workstation.

  18. 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.

  19. 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.

  20. Hydrogen termination for extended queue times for low temperature epitaxy

    NASA Astrophysics Data System (ADS)

    Brabant, P.; Ferrara, J.; Pagliaro, B.; Weeks, K.; Rittgers, M.; Scott, R.; Zhang, Y.; Landin, T.; Irving, T.; Spear, J.; Italiano, J.; Thomas, S. G.

    2008-12-01

    We investigated the oxidation of hydrogen terminated Si (1 0 0) surfaces stored in Fab air environment. Hydrogen termination for extended queue times with wet and dry clean techniques is investigated. Comparison of X-ray photoelectron spectroscopy (XPS) data and empirical results from Si capping layer are used to determine re-oxidation of the Si surface over extended queue times. H 2 pre-bake efficiency with the best clean method, 100:1 HF, in situ rinsed with degasified DI water was tested. 2 min 850 °C and 900 °C H 2 bakes, at 10 Torr pressure, both resulted in atomically clean surfaces below SIMS detectable for up to 96 h queue time in lab ambient (controlled 35-40% relative humidity and temperature range of 22-25 °C).

  1. Entropy estimation for M/M/1 queueing systems

    NASA Astrophysics Data System (ADS)

    Regnault, Philippe

    2012-05-01

    The aim of this paper is to estimate the entropy of Markovian queueing systems. The marginal entropy and entropy rate of a stochastic process are well-known to measure its uncertainty. When only observations of the process are available, the need to estimate themarises. Regnault [5, 6] provide estimators with good asymptotic properties of the entropy of continuous-time ergodic Markov processes. We specialize these results in the context of birth-death processes used in continuous-time M/M/1 queueing systems. Links with maximum entropy arguments are used to characterize the asymptotic behavior of the estimators.

  2. Road safety issues for bus transport management.

    PubMed

    Cafiso, Salvatore; Di Graziano, Alessandro; Pappalardo, Giuseppina

    2013-11-01

    Because of the low percentage of crashes involving buses and the assumption that public transport improves road safety by reducing vehicular traffic, public interest in bus safety is not as great as that in the safety of other types of vehicles. It is possible that less attention is paid to the significance of crashes involving buses because the safety level of bus systems is considered to be adequate. The purpose of this study was to evaluate the knowledge and perceptions of bus managers with respect to safety issues and the potential effectiveness of various technologies in achieving higher safety standards. Bus managers were asked to give their opinions on safety issues related to drivers (training, skills, performance evaluation and behaviour), vehicles (maintenance and advanced devices) and roads (road and traffic safety issues) in response to a research survey. Kendall's algorithm was used to evaluate the level of concordance. The results showed that the majority of the proposed items were considered to have great potential for improving bus safety. The data indicated that in the experience of the participants, passenger unloading and pedestrians crossing near bus stops are the most dangerous actions with respect to vulnerable users. The final results of the investigation showed that start inhibition, automatic door opening, and the materials and internal architecture of buses were considered the items most strongly related to bus passenger safety. Brake assistance and vehicle monitoring systems were also considered to be very effective. With the exception of driver assistance systems for passenger and pedestrian safety, the perceptions of the importance of other driver assistance systems for vehicle monitoring and bus safety were not unanimous among the bus company managers who participated in this survey. The study results showed that the introduction of new technologies is perceived as an important factor in improving bus safety, but a better understanding of their actual effectiveness and related risk factor avoidance must be developed to permit their useful implementation in bus fleets. PMID:23850401

  3. A new bus lane on urban expressway with no-bay bus stop

    NASA Astrophysics Data System (ADS)

    Tian, Zhao; Jia, Limin

    2016-01-01

    The sharp increase in residents and vehicles causes heavy traffic pressure in many cities. To ease traffic congestion, it has been the common sense that we should develop public transit system. The priority of the bus appears particularly necessary with the rapid development of the public transport system. The bus lane is an important embodiment of the bus priority. Focusing on the problem of the unreasonable dedicated bus lane (DBL) under the lower ratio of buses, this paper proposed a new bus lane with limited physical length. And this bus lane can reduce the lane-changing conflict caused by the buses and cars running on roads without bus lanes. Based on the cellular automata (CA) traffic flow model and the lane-changing behavior of the vehicle including the optional lane-changing and the mandatory lane-changing, a three-lane traffic model with an isolated no-bay bus stop is proposed. The ordinary three-lane traffic without a bus lane and the cases of traffic with a DBL or the proposed bus lane are simulated, and the comparisons in the form of the fundamental diagrams are made among them. It is shown that the no-bay bus stop can act as a bottleneck on the traffic flow because of the mandatory lane-changing behavior. Under a certain ratio of the bus number to the total vehicles number, (1) the traffic with the proposed bus lane has less lane-changing conflict and can provide higher traffic capacity than the ordinary traffic without a bus lane, (2) compared with the DBL, the proposed bus lane is advantageous in easing congestion on the ordinary lanes when the traffic flow is high and can avoid unreasonable allocation of the road resources.

  4. Hidden Savings in your Bus Budget

    ERIC Educational Resources Information Center

    Newby, Ruth

    2005-01-01

    School transportation industry statistics show the annual average costs for operating and maintaining a single school bus range from $34,000 to $38,000. Operating a school bus fleet at high efficiency has a real impact on the dollars saved for a school district and the reliability of transportation service to students. In this article, the author…

  5. How Parents Can Promote School Bus Safety.

    ERIC Educational Resources Information Center

    Tofany, Vincent L.

    1982-01-01

    The president of the National Safety Council suggests ways that parents can promote school bus safety, with emphasis on preventing accidents outside the bus. Parents can explain safety rules to their children and work with their parent teacher associations and school administrators to plan and enforce safety regulations. (PP)

  6. Alternative Fuel School Bus Information Resources

    SciTech Connect

    Not Available

    2004-04-01

    This 4-page Clean Cities fact sheet provides a list of important resources for learning more about alternative fuels in school buses. It includes information regarding Alternative Fuel School Bus Manufacturers, Alternative Fuel HD Engine Manufacturers, Alternative Fuel School Bus Operators, and Key Web Resources for Alternative Fuels.

  7. Two Innovations in Bus Driver Training

    ERIC Educational Resources Information Center

    School Management, 1972

    1972-01-01

    Discusses driver and human relations training for school bus drivers. A driver training program in California aims at reaching all 19,000 school bus drivers. A human relations training program in Seattle focuses on bettering student-driver and driver-administrator relations. (DN)

  8. Controlling Multiple Registers on a Computer Bus

    NASA Technical Reports Server (NTRS)

    Brokl, Stanley S.

    1987-01-01

    Number of addressable registers increased. Monitoring and controlling interface circuit expands capabilities of DR11-C (or equivalent) input/output port for computer that communicates with peripheral equipment via UNIBUS (or equivalent) data bus. Using only three address locations on bus, unit enables any number of external registers to be addressed, read, or written.

  9. Resource Selection Using Execution and Queue Wait Time Predictions

    NASA Technical Reports Server (NTRS)

    Smith, Warren; Wong, Parkson; Biegel, Bryan (Technical Monitor)

    2001-01-01

    We developed techniques to predict application execution times for instance-based learning with an average error of 33% of average run time. We developed techniques to predict queue wait times that included a simulation of scheduling algorithms and execution time predictions. We implemented these techniques for the NAS Origin cluster.

  10. 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…

  11. 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. PMID:16598644

  12. Interprocessor bus switching system for simultaneous communication in plural bus parallel processing system

    DOEpatents

    Atac, R.; Fischler, M.S.; Husby, D.E.

    1991-01-15

    A bus switching apparatus and method for multiple processor computer systems comprises a plurality of bus switches interconnected by branch buses. Each processor or other module of the system is connected to a spigot of a bus switch. Each bus switch also serves as part of a backplane of a modular crate hardware package. A processor initiates communication with another processor by identifying that other processor. The bus switch to which the initiating processor is connected identifies and secures, if possible, a path to that other processor, either directly or via one or more other bus switches which operate similarly. If a particular desired path through a given bus switch is not available to be used, an alternate path is considered, identified and secured. 11 figures.

  13. Interprocessor bus switching system for simultaneous communication in plural bus parallel processing system

    DOEpatents

    Atac, Robert; Fischler, Mark S.; Husby, Donald E.

    1991-01-01

    A bus switching apparatus and method for multiple processor computer systems comprises a plurality of bus switches interconnected by branch buses. Each processor or other module of the system is connected to a spigot of a bus switch. Each bus switch also serves as part of a backplane of a modular crate hardware package. A processor initiates communication with another processor by identifying that other processor. The bus switch to which the initiating processor is connected identifies and secures, if possible, a path to that other processor, either directly or via one or more other bus switches which operate similarly. If a particular desired path through a given bus switch is not available to be used, an alternate path is considered, identified and secured.

  14. Analog bus driver and multiplexer

    NASA Technical Reports Server (NTRS)

    Pain, Bedabrata (Inventor); Hancock, Bruce (Inventor); Cunningham, Thomas J. (Inventor)

    2012-01-01

    For a source-follower signal chain, the ohmic drop in the selection switch causes unacceptable voltage offset, non-linearity, and reduced small signal gain. For an op amp signal chain, the required bias current and the output noise rises rapidly with increasing the array format due to a rapid increase in the effective capacitance caused by the Miller effect boosting up the contribution of the bus capacitance. A new switched source-follower signal chain circuit overcomes limitations of existing op-amp based or source follower based circuits used in column multiplexers and data readout. This will improve performance of CMOS imagers, and focal plane read-out integrated circuits for detectors of infrared or ultraviolet light.

  15. FAST BUS Test Box (LAIKA) (Engineering Materials)

    SciTech Connect

    Not Available

    1983-01-01

    The assembly drawing AD 135-518-00-RO, and the drawings referenced thereon, provide the data and specifications for constructing the LAIKA Test Box. Some drawings are not available, although they are listed on the material lists included. The assembly is a manual tester for FAST BUS modules, both masters and slaves. FAST BUS signals are generated by means of switches or push buttons and provide the state of the bus lines by lighting LED's. The box acts as either a master or slave - depending upon the module under test. It also acts as an ATC to test the arbitration logic of a master or ATC device.

  16. 49 CFR 605.19 - Approval of school bus operations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Approval of school bus operations. 605.19 Section... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION SCHOOL BUS OPERATIONS School Bus Agreements § 605.19 Approval of school bus operations. (a) The Administrator will consider the comments filed by private school...

  17. Entrainment of a Synthetic Oscillator through Queueing Coupling

    NASA Astrophysics Data System (ADS)

    Hochendoner, Philip; Mather, William; Butzin, Nicholas; Ogle, Curtis

    2014-03-01

    Many biological systems naturally exhibit (often noisy) oscillatory patterns that are capable of being entrained by external stimuli, though the mechanism of entrainment is typically obscured by the complexity of native networks. A synthetic biology approach, where genetic programs are wired ``by hand,'' has proven useful in this regard. In the present study, we use a synthetic oscillator in Escherichia coli to demonstrate a novel and potentially widespread mechanism for biological entrainment: competition of proteins for degradation by common pathway, i.e. a entrainment by a bottleneck. To faithfully represent the discrete and stochastic nature of this bottleneck, we leverage results from a recent biological queueing theory, where in particular, the queueing theoretic concept of workload is discovered to simplify the analysis. NSF Award 1330180.

  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. Resource Selection Using Execution and Queue Wait Time Predictions

    NASA Technical Reports Server (NTRS)

    Smith, Warren; Wong, Parkson; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    Computational grids provide users with many possible places to execute their applications. We wish to help users select where to run their applications by providing predictions of the execution times of applications on space shared parallel computers and predictions of when scheduling systems for such parallel computers will start applications. Our predictions are based on instance based learning techniques and simulations of scheduling algorithms. We find that our execution time prediction techniques have an average error of 37 percent of the execution times for trace data recorded from SGI Origins at NASA Ames Research Center and that this error is 67 percent lower than the error of user estimates. We also find that the error when predicting how long applications will wait in scheduling queues is 95 percent of mean queue wait times when using our execution time predictions and this is 57 percent lower than if we use user execution time estimates.

  20. 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.

  1. Capacity-constrained traffic assignment in networks with residual queues

    SciTech Connect

    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 proposed 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.

  2. ARQ with sequential decoding of packetized data - Queueing analysis

    NASA Astrophysics Data System (ADS)

    Shacham, N.

    1984-10-01

    The operation of a sequential decoder in a packet-switching environment is considered. Packets arrive randomly at the decoder, and a packet is stored in a buffer if the decoder is busy upon its arrival. The decoder devotes no more than a time-out period of predetermined length to the decoding of any single packet. If packet decoding is completed within that period, the packet leaves the system. Otherwise, it is retransmitted and its decoding starts anew. While a packet is retransmitted, the decoder decodes another packet that resides in its buffer. An upper bound on the maximum rate of packets that can be supported by the channel-decoder combination is derived, and the optimum time-out that maximizes that rate is determined. A discrete-time model of the decoder's queue is presented, and the average queue length and throughput are evaluated.

  3. Analysis and simulation of a city bus route

    NASA Astrophysics Data System (ADS)

    Kar, Leow Soo

    2014-12-01

    Public transport in crowded cities, in particular bus services play an essential role in the mobility of its citizenry. However, an efficient, reliable and safe bus system is still a distant dream of many cities. This paper uses a simulation approach to provide some insight into the factors that contribute to the service quality of a bus system. SAS Simulation Studio is used to model a city bus route. The simulation model consists of a bus depot, bus stops, terminal station and a bus route. Parameters used in the simulation include the number of buses serving the route, maximum bus capacity, inter departure time of buses, travel time between stops, number of passengers boarding and alighting. The simulation is applied to a real bus route in Kuala Lumpur city center and a sensitivity analysis is performed to evaluate how the different variables affect the service quality of the bus system.

  4. Queue Resource Reallocation Strategy for Traffic Systems in Scale-Free Network

    NASA Astrophysics Data System (ADS)

    Zhang, Shuai; Liang, Man-Gui; Jiang, Zhong-Yuan; Li, Hui-Jia

    2013-03-01

    In real communication systems, each node has a finite queue length to store packets due to physical constraints. In this paper, we propose a queue resource allocation strategy for traffic dynamics in scale-free networks. With a finite resource of queue, the allocation of queue length on node i is based on Bi, where Bi is the generalized betweenness centrality of node i. The overall traffic capacity of a network system can be evaluated by the critical packet generating rate (Rc). Through the use of the proposed queue allocation scheme for the shortest path protocol and efficient routing protocol, our strategy performs better than the uniform queue length allocation strategy, which is demonstrated by a larger value of the critical generating rate. We also give a method to estimate the network traffic capacity theoretically.

  5. TMS communications software. Volume 2: Bus interface unit

    NASA Technical Reports Server (NTRS)

    Gregor, P. J.

    1979-01-01

    A data bus communication system to support the space shuttle's Trend Monitoring System (TMS) and to provide a basis for evaluation of the bus concept is described. Installation of the system included developing both hardware and software interfaces between the bus and the specific TMS computers and terminals. The software written for the microprocessor-based bus interface units is described. The software implements both the general bus communications protocol and also the specific interface protocols for the TMS computers and terminals.

  6. The Impact on Traffic Safety in Bus Stop

    NASA Astrophysics Data System (ADS)

    Zhang, Kailun; Guang, Xiaoping; Qian, Yongsheng

    The article improves the attraction of public transportation system when the safety is taken into account during the selection of bus stops. In this paper, the characteristics of traffic conflict at bus stops is analyzed from various types of bus stops and the applicability of bus stations is proposed in comply with provisions of security. It has a certain reference value on selection of bus stops.

  7. 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.

  8. A Brownian model for multiclass queueing networks with finite buffers

    NASA Astrophysics Data System (ADS)

    Dai, Wanyang

    2002-07-01

    This paper is concerned with the heavy traffic behavior of a type of multiclass queueing networks with finite buffers. The network consists of d single server stations and is populated by K classes of customers. Each station has a finite capacity waiting buffer and operates under first-in first-out (FIFO) service discipline. The network is assumed to have a feedforward routing structure under a blocking scheme. A server stops working when the downstream buffer is full. The focus of this paper is on the Brownian model formulation. More specifically, the approximating Brownian model for the networks is proposed via the method of showing a pseudo-heavy-traffic limit theorem which states that the limit process is a reflecting Brownian motion (RBM) if the properly normalized d-dimensional workload process converges in distribution to a continuous process. Numerical algorithm with finite element method has been designed to effectively compute the solution of the Brownian model (W. Dai, Ph.D. thesis (1996); X. Shen et al. The finite element method for computing the stationary distribution of an SRBM in a hypercube with applications to finite buffer queueing networks, under revision for Queueing Systems).

  9. Systems evaluation of thermal bus concepts

    NASA Technical Reports Server (NTRS)

    Stalmach, D. D.

    1982-01-01

    Thermal bus concepts, to provide a centralized thermal utility for large, multihundred kilowatt space platforms, were studied and the results are summarized. Concepts were generated, defined, and screened for inclusion in system level thermal bus trades. Parametric trade studies were conducted in order to define the operational envelope, performance, and physical characteristics of each. Two concepts were selected as offering the most promise for thermal bus development. All of four concepts involved two phase flow in order to meet the required isothermal nature of the thermal bus. Two of the concepts employ a mechanical means to circulate the working fluid, a liquid pump in one case and a vapor compressor in another. Another concept utilizes direct osmosis as the driving force of the thermal bus. The fourth concept was a high capacity monogroove heat pipe. After preliminary sizing and screening, three of these concepts were selected to carry into the trade studies. The monogroove heat pipe concept was deemed unsuitable for further consideration because of its heat transport limitations. One additional concept utilizing capillary forces to drive the working fluid was added. Parametric system level trade studies were performed. Sizing and weight calculations were performed for thermal bus sizes ranging from 5 to 350 kW and operating temperatures in the range of 4 to 120 C. System level considerations such as heat rejection and electrical power penalties and interface temperature losses were included in the weight calculations.

  10. Performance evaluation of input and output queueing techniques in ATM switching systems

    NASA Astrophysics Data System (ADS)

    Delre, Enrico; Fantacci, Romano

    1993-10-01

    In this paper, alternatives to model a fast packet switching system are analyzed. A nonblocking switch fabric which runs at the same speed as the input/output links is considered. The performance of the considered approaches have been derived by theoretical analysis and computer simulations. Performance comparison between input queueing approaches with different selection policies are presented. Novel input and output queueing techniques are also proposed. In particular it is shown that, depending on the implementation, the novel input queueing approach studied in this paper achieves the same performance as the optimum (output) queueing alternative, without resorting to a faster packet switch fabric.

  11. 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.

  12. 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.

  13. An empirical assessment of priority queues in event-driven molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Marín, Mauricio; Cordero, Patricio

    1995-12-01

    In the last decades a number of near optimal priority queues have been developed. Many of these priority queues are suitable for the efficient management of events generated during simulations of hard-particle systems. In this paper we compare the execution times of the fastest priority queues known today as well as some forms of binary search trees used as priority queues. We conclude that an unusual adaptation of a strictly balanced binary tree has the best performance for this class of simulations.

  14. School Bus and School Pupil Activity Bus Inspection and Maintenance Guide.

    ERIC Educational Resources Information Center

    Sowash, Fred W.

    This publication deals with suggested maintenance standards that apply to vehicles used for pupil transportation in California and covers all the safety-related systems that are common to most buses. The guide has been prepared to help all school bus and school pupil activity bus operators set up an inspection and preventive maintenance program…

  15. Dynamic Bus Travel Time Prediction Models on Road with Multiple Bus Routes

    PubMed Central

    Bai, Cong; Peng, Zhong-Ren; Lu, Qing-Chang; Sun, Jian

    2015-01-01

    Accurate and real-time travel time information for buses can help passengers better plan their trips and minimize waiting times. A dynamic travel time prediction model for buses addressing the cases on road with multiple bus routes is proposed in this paper, based on support vector machines (SVMs) and Kalman filtering-based algorithm. In the proposed model, the well-trained SVM model predicts the baseline bus travel times from the historical bus trip data; the Kalman filtering-based dynamic algorithm can adjust bus travel times with the latest bus operation information and the estimated baseline travel times. The performance of the proposed dynamic model is validated with the real-world data on road with multiple bus routes in Shenzhen, China. The results show that the proposed dynamic model is feasible and applicable for bus travel time prediction and has the best prediction performance among all the five models proposed in the study in terms of prediction accuracy on road with multiple bus routes. PMID:26294903

  16. Dynamic Bus Travel Time Prediction Models on Road with Multiple Bus Routes.

    PubMed

    Bai, Cong; Peng, Zhong-Ren; Lu, Qing-Chang; Sun, Jian

    2015-01-01

    Accurate and real-time travel time information for buses can help passengers better plan their trips and minimize waiting times. A dynamic travel time prediction model for buses addressing the cases on road with multiple bus routes is proposed in this paper, based on support vector machines (SVMs) and Kalman filtering-based algorithm. In the proposed model, the well-trained SVM model predicts the baseline bus travel times from the historical bus trip data; the Kalman filtering-based dynamic algorithm can adjust bus travel times with the latest bus operation information and the estimated baseline travel times. The performance of the proposed dynamic model is validated with the real-world data on road with multiple bus routes in Shenzhen, China. The results show that the proposed dynamic model is feasible and applicable for bus travel time prediction and has the best prediction performance among all the five models proposed in the study in terms of prediction accuracy on road with multiple bus routes. PMID:26294903

  17. Sexual Harassment on the School Bus: Supporting and Preparing Bus Drivers to Respond Appropriately

    ERIC Educational Resources Information Center

    Allen, Melissa; Young, Ellie L.; Ashbaker, Betty Y.; Heaton, Emily; Parkinson, Marisa

    2003-01-01

    Sexual harassment is commonplace in schools, particularly among adolescents. Although information on this topic is typically gathered from students and teachers, this study collected information from school bus drivers. Based on feedback from 58 school bus drivers, 39 (67%) reported observing students making sexual comments or jokes. Almost half…

  18. 77 FR 6172 - Discretionary Bus and Bus Facilities Program and National Research Program Funds.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-07

    ...The Federal Transit Administration (FTA) announces the availability of discretionary funds from the Fiscal Year (FY) 2012 Section 5309(b)(3) Bus and Bus Facilities Program and the FY 2011 Section 5312 National Research Program for continuing support of the Federal Interagency Coordinating Council on Access and Mobility's (Coordinating Council or CCAM) Veterans Transportation and Community......

  19. 75 FR 74134 - State of Good Repair Bus and Bus Facilities Discretionary Program Funds

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-30

    ...The U.S. Department of Transportation's (DOT) Federal Transit Administration (FTA) announces the selection of projects funded with Section 5309 Bus and Bus Facilities program funds in support of the State of Good Repair (SGR) Initiative, which was announced in the State of Good Repair Initiative Notice of Funding Availability on May 4, 2010. The SGR Initiative makes funds available to public......

  20. 76 FR 68819 - State of Good Repair Bus and Bus Facilities Discretionary Program Funds

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-07

    ...The U.S. Department of Transportation's (DOT) Federal Transit Administration (FTA) announces the selection of projects funded with Section 5309 Bus and Bus Facilities program funds in support of the State of Good Repair (SGR) Initiative, which was announced in the State of Good Repair Initiative Notice of Funding Availability on June 24, 2011. The SGR Initiative makes funds available to public......

  1. Fuel Cell Bus Takes a Starring Role in the BurbankBus Fleet (Fact Sheet)

    SciTech Connect

    Not Available

    2010-05-01

    This fact sheet reports on the City of Burbank, California's fuel cell bus demonstration project and the U.S. Department of Energy's (DOE) involvement. Included are specifications for the fuel cell bus and information about its operation. BurbankBus, the city's mass transit entity, received a grant from the California Air Resources Board to fund its zero-emission bus demonstration and is collaborating with DOE's Fuel Cell Technologies Program to evaluate the bus performance. DOE's National Renewable Energy Laboratory will collect and analyze performance and operations data for at least one year. Researchers will use the data to better understand the technology and determine future development work. In addition, demonstration information will help fleets make informed purchase decisions.

  2. Ramp Metering by Limitation of Density and Queue Length

    NASA Astrophysics Data System (ADS)

    Kamel, Boumediene; Benasser, Amar; Jolly, Daniel

    2009-03-01

    As shown by many works and studies, the control of traffic flow remains the best and the efficient solution of the congestion problems. The ramp metering is a means to reduce congestion effects, it has shown his effectiveness to improve the flow and consequently to reduce the total time spent (TTS) by the vehicles in the network. In Kamel et al. [2008] the concept of flatness-based control was applied to regulate the flow at the mainline section of the road on the traffic flow model LWR. This work was preceded by Abouaïssa et al. [2006]. In this article we have proceeded the same way to set the flat output for a second order model METANET. Unfortunately we were unable to prove that the system is flat and therefore define density as flat output, but we manage to define the control laws in order to respect constraints on density and queue length at the on-ramp. The idea is to express the control variable (the outflow of the on-ramp) according to the output (density or queue length at the on-ramp), then inject it in the system. We use this control method in the ramp metering case. The first aim of the control is to keep the density in the segment where the on-ramp is connected below a density (called the target density YT) for which we have the lowest TTS, and the second aim is to keep the queue length at the on-ramp below a maximum value. In order to evaluate the controller's efficiency and applicability, a comparison is made with traditional ALINEA based controller. We illustrate this approach by comparing the cases 'no control' and 'ramp metering' for a simple network.

  3. School bus routing using genetic algorithms

    NASA Astrophysics Data System (ADS)

    Thangiah, Sam R.; Nygard, Kendall E.

    1992-03-01

    The school bus routing problem involves transporting students from predefined locations to the school using a fleet of school buses with varying capacity. The objective is to minimize the fleet size in addition to minimizing the distance traveled by the buses and the travel time of the students. As the school bus routing problem belongs to the NP-complete class of problems, search strategies based on heuristic methods are most promising for problems in this class. GENROUTER is a system that uses genetic algorithms, an adaptive heuristic search strategy, for routing school buses. The GENROUTER system was used to route school buses for two school districts. The routes obtained by GENROUTER system were superior to those obtained by the CHOOSE school bus routing system and the current routes in use by the two school districts.

  4. Rainfall time series synthesis from queue scheduling of rain event fractals over radio links

    NASA Astrophysics Data System (ADS)

    Alonge, Akintunde A.; Afullo, Thomas J.

    2015-12-01

    Rainfall attenuation over wireless networks stems from random fluctuations in the natural process of arriving rainfall rates over radio links. This arrival process results in discernible rainfall traffic pattern which manifests as naturally scheduled and queue-generated rain spikes. Hence, the phenomenon of rainfall process can be approached as a semi-Markovian queueing process, with event characteristics dependent on queue parameters. However, a constraint to this approach is the knowledge of the physical characteristics of queue-generated rain spikes. Therefore, this paper explores the probability theory and descriptive mathematics of rain spikes in rainfall processes. This investigation presents the synthesis of rainfall queue with rain spikes at subtropical and equatorial locations of Durban (29°52'S, 30°58'E) and Butare (2°36'S, 29°44'E), respectively. The resulting comparative analysis of rainfall distributions, using error analysis at both locations, reveals that queue-generated rainfall compares well with measured rainfall data set. This suggests that the time-varying process of rainfall, though stochastic, can be synthesized via queue scheduling with the application of relevant queue parameters at any location.

  5. Factors affecting the probability of bus drivers being at-fault in bus-involved accidents.

    PubMed

    Goh, Kelvin; Currie, Graham; Sarvi, Majid; Logan, David

    2014-05-01

    Previous research has provided little insight into factors that influence the probability of bus drivers being at-fault in bus-involved accidents. In this study, an analysis was conducted on accident data compiled by a bus company that include an assessment on whether the bus driver was deemed by the company to hold primary responsibility for accident occurrence. Using a mixed logit modelling approach, roadway/environmental, vehicle and driver related variables that were identified to be influential were road type, speed limit, traffic/lighting conditions, bus priority, bus age/length and driver's age/gender/experience/historic at-fault accident record. Results were indicative of possible confined road-space issues that bus drivers face along routes with roadside traffic friction and point to the provision of exclusive right of way for buses as a possible way to address this. Results also suggest benefits in assigning routes comprising mainly divided roads as well as newer and shorter buses to less experienced drivers. PMID:24486771

  6. Proposal for a novel optical bus system using optical sheet bus technology

    NASA Astrophysics Data System (ADS)

    Funada, Masao; Ozeki, Shinobu; Hamada, Tsutomu; Sakai, Kazuhiro; Shiotani, Takekazu; Hirota, Masaki; Kyozuka, Shinya; Okada, Junji; Kobayashi, Ken-ichi; Fujimagari, Hiroshi; Ozawa, Takashi

    1999-04-01

    Conventional electrical bus system technologies are encountered their physical borders in terms of transmission length and parasitic capacity of lines, and thus, many optical interconnection technologies are proposed to solve the problems in the electrical circuits. In this paper, we propose a new optical bus with sheet like shape technology using diffusion controlled light transmission in the multi- planar waveguides that makes capability of broadcasting, simultaneous bidirectional transmission, easy alignment and plural multiplex transmission. We have fabricated a basic model using optical sheet bus technology for the first time and evaluate them at 500MHz clock operation as follows: (1) synchronous broadcasting transmission to control transmission delay; (2) simultaneous bidirectional transmission in the same waveguide; (3) multiplex transmission such as time division multiplexing, wavelength division multiplexing and so on. Through this fabrication and evaluation, we can pick up some approach to put the optical sheet bus technology into practice with feature as follows: (a) simple design rule for multi-accessible bus systems like as shared memory bus systems, which needs faster speed; (b) added-value of multiplex transmission ways that reduce circuit frequency, minimize power consumption, maximize transmission bandwidth, and bring about no-wait communications for the bus systems.

  7. Risk factors affecting fatal bus accident severity: Their impact on different types of bus drivers.

    PubMed

    Feng, Shumin; Li, Zhenning; Ci, Yusheng; Zhang, Guohui

    2016-01-01

    While the bus is generally considered to be a relatively safe means of transportation, the property losses and casualties caused by bus accidents, especially fatal ones, are far from negligible. The reasons for a driver to incur fatalities are different in each case, and it is essential to discover the underlying risk factors of bus fatality severity for different types of drivers in order to improve bus safety. The current study investigates the underlying risk factors of fatal bus accident severity to different types of drivers in the U.S. by estimating an ordered logistic model. Data for the analysis are retrieved from the Buses Involved in Fatal Accidents (BIFA) database from the USA for the years 2006-2010. Accidents are divided into three levels by counting their equivalent fatalities, and the drivers are classified into three clusters by the K-means cluster analysis. The analysis shows that some risk factors have the same impact on different types of drivers, they are: (a) season; (b) day of week; (c) time period; (d) number of vehicles involved; (e) land use; (f) manner of collision; (g) speed limit; (h) snow or ice surface condition; (i) school bus; (j) bus type and seating capacity; (k) driver's age; (l) driver's gender; (m) risky behaviors; and (n) restraint system. Results also show that some risk factors only have impact on the "young and elder drivers with history of traffic violations", they are: (a) section type; (b) number of lanes per direction; (c) roadway profile; (d) wet road surface; and (e) cyclist-bus accident. Notably, history of traffic violations has different impact on different types of bus drivers. PMID:26513334

  8. Bus training for developmentally disabled adults.

    PubMed

    Robinson, D; Griffith, J; McComish, K; Swasbrook, K

    1984-07-01

    The effectiveness of a program combining classroom and community training in the teaching of bus-riding skills to developmentally disabled adults. These skills were taught sequentially using questions about a slide presentation, role playing, and performance in the natural environment. The experimental design was based upon the work of Neef, Iwata, and Page (1978). Test trials were conducted after each phase of training. Results showed that all subjects learned the necessary bus-riding skills and maintained their performance throughout the follow-up period of at least 1 year. The combination training method proved to be efficient and cost effective. PMID:6465211

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

    DOEpatents

    Bent, John M.; Faibish, Sorin

    2015-08-18

    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; 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.

  10. 24. DETAIL INTERIOR VIEW OF GENERATOR BUS POTENTIAL FOR UNIT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. DETAIL INTERIOR VIEW OF GENERATOR BUS POTENTIAL FOR UNIT NO 1 IN BUS CELL GALLERY ON LEVEL +77 OF POWERHOUSE #1. - Bonneville Project, Powerhouse No.1, Spanning Bradford Slough, from Bradford Island, Bonneville, Multnomah County, OR

  11. The crew activity planning system bus interface unit

    NASA Technical Reports Server (NTRS)

    Allen, M. A.

    1979-01-01

    The hardware and software designs used to implement a high speed parallel communications interface to the MITRE 307.2 kilobit/second serial bus communications system are described. The primary topic is the development of the bus interface unit.

  12. Analysis of a diesel-electric hybrid urban bus system

    SciTech Connect

    Marr, W.W.; Sekar, R.R.; Ahlheim, M.C.

    1993-08-01

    A hybrid bus powered by a diesel engine and a battery pack has been analyzed over an idealized bus-driving cycle in Chicago. Three hybrid configurations, two parallel and one series, have been evaluated. The results indicate that the fuel economy of a hybrid bus, taking into account the regenerative braking, is comparable with that of a conventional diesel bus. Life-cycle costs are slightly higher because of the added weight and cost of the battery.

  13. Analysis of a diesel-electric hybrid urban bus system

    NASA Astrophysics Data System (ADS)

    Marr, W. W.; Sekar, R. R.; Ahlheim, M. C.

    A hybrid bus powered by a diesel engine and a battery pack was analyzed over an idealized bus-driving cycle in Chicago. Three hybrid configurations, two parallel and one series, were evaluated. The results indicate that the fuel economy of a hybrid bus, taking into account the regenerative braking, is comparable with that of a conventional diesel bus. Life-cycle costs are slightly higher because of the added weight and cost of the battery.

  14. Applications of queueing theory to stochastic models of gene expression

    NASA Astrophysics Data System (ADS)

    Kulkarni, Rahul

    2012-02-01

    The intrinsic stochasticity of cellular processes implies that analysis of fluctuations (`noise') is often essential for quantitative modeling of gene expression. Recent single-cell experiments have carried out such analysis to characterize moments and entire probability distributions for quantities of interest, e.g. mRNA and protein levels across a population of cells. Correspondingly, there is a need to develop general analytical tools for modeling and interpretation of data obtained from such single-cell experiments. One such approach involves the mapping between models of stochastic gene expression and systems analyzed in queueing theory. The talk will provide an overview of this approach and discuss how theorems from queueing theory (e.g. Little's Law) can be used to derive exact results for general stochastic models of gene expression. In the limit that gene expression occurs in bursts, analytical results can be obtained which provide insight into the effects of different regulatory mechanisms on the noise in protein steady-state distributions. In particular, the approach can be used to analyze the effect of post-transcriptional regulation by non-coding RNAs leading to new insights and experimentally testable predictions.

  15. Queueing-Based Synchronization and Entrainment for Synthetic Gene Oscillators

    NASA Astrophysics Data System (ADS)

    Mather, William; Butzin, Nicholas; Hochendoner, Philip; Ogle, Curtis

    Synthetic gene oscillators have been a major focus of synthetic biology research since the beginning of the field 15 years ago. They have proven to be useful both for biotechnological applications as well as a testing ground to significantly develop our understanding of the design principles behind synthetic and native gene oscillators. In particular, the principles governing synchronization and entrainment of biological oscillators have been explored using a synthetic biology approach. Our work combines experimental and theoretical approaches to specifically investigate how a bottleneck for protein degradation, which is present in most if not all existing synthetic oscillators, can be leveraged to robustly synchronize and entrain biological oscillators. We use both the terminology and mathematical tools of queueing theory to intuitively explain the role of this bottleneck in both synchronization and entrainment, which extends prior work demonstrating the usefulness of queueing theory in synthetic and native gene circuits. We conclude with an investigation of how synchronization and entrainment may be sensitive to the presence of multiple proteolytic pathways in a cell that couple weakly through crosstalk. This work was supported by NSF Grant #1330180.

  16. A Queueing-Based Approach to Overload Detection

    NASA Astrophysics Data System (ADS)

    Mandjes, Michel; Żuraniewski, Piotr

    The control of communication networks critically relies on procedures capable of detecting unanticipated load changes. In this paper we develop such techniques, in a setting in which each connection consumes roughly the same amount of bandwidth (with VoIP as a leading example). For the situation of exponential holding times an explicit analysis can be performed in a large-deviations regime, leading to approximations of the test statistic of interest (and, in addition, to results for the transient of the M/M/∞ queue, which are of independent interest). This procedure being applicable to exponential holding times only, and also being numerically rather involved, we then develop an approximate procedure for general holding times. In this procedure we record the number of trunks occupied at equidistant points in time {Δ},2{Δ},ldots, where {Δ} is chosen sufficiently large to safely assume that the samples are independent; this procedure is backed by results on the transient of the M/G/∞ queue. The validity of the testing procedures is demonstrated through an extensive set of numerical experiments.

  17. Queueing up for enzymatic processing: correlated signaling through coupled degradation.

    PubMed

    Cookson, Natalie A; Mather, William H; Danino, Tal; Mondragón-Palomino, Octavio; Williams, Ruth J; Tsimring, Lev S; Hasty, Jeff

    2011-01-01

    High-throughput technologies have led to the generation of complex wiring diagrams as a post-sequencing paradigm for depicting the interactions between vast and diverse cellular species. While these diagrams are useful for analyzing biological systems on a large scale, a detailed understanding of the molecular mechanisms that underlie the observed network connections is critical for the further development of systems and synthetic biology. Here, we use queueing theory to investigate how 'waiting lines' can lead to correlations between protein 'customers' that are coupled solely through a downstream set of enzymatic 'servers'. Using the E. coli ClpXP degradation machine as a model processing system, we observe significant cross-talk between two networks that are indirectly coupled through a common set of processors. We further illustrate the implications of enzymatic queueing using a synthetic biology application, in which two independent synthetic networks demonstrate synchronized behavior when common ClpXP machinery is overburdened. Our results demonstrate that such post-translational processes can lead to dynamic connections in cellular networks and may provide a mechanistic understanding of existing but currently inexplicable links. PMID:22186735

  18. Development and Implementation of a Bus Driver Training Program.

    ERIC Educational Resources Information Center

    Buchovecky, John G.

    A bus driver training program was developed and implemented in a rural school district in an effort to improve the driving skills of the bus drivers. The program was tailored to meet the needs of the bus drivers and utilized various community agencies for demonstration and teaching purposes. The subject areas included in the program were driver…

  19. Staying Safe in the Car and on the Bus

    MedlinePlus

    ... Crushes What's a Booger? Staying Safe in the Car and on the Bus KidsHealth > For Kids > Staying Safe in the Car and on the Bus Print A A A ... re probably getting there by riding in a car or a school bus. Most kids spend some ...

  20. Yet Another School Bus Tragedy Proves Drivers Need More Training.

    ERIC Educational Resources Information Center

    Shannon, James W., Jr.

    1983-01-01

    A March 1982 Jonesboro, Arkansas, school bus accident in which nine people were killed has rekindled the debate over school bus safety, says the author. The article discusses briefly the opposition historically between school bus manufacturers and safety advocates and presents cost-benefit arguments concerning mandatory seat-belt installation.…

  1. Information management advanced development. Volume 3: Digital data bus breadboard

    NASA Technical Reports Server (NTRS)

    Gerber, C. R.

    1972-01-01

    The design, development, and evaluation of the digital data bus breadboard for the modular space station are discussed. Subjects presented are: (1) requirements summary, (2) parametric data for bus design, (3) redundancy concepts, and (4) data bus breadboard performance and interface requirements.

  2. Functional Bus Driver-Pupil Passenger Relationships.

    ERIC Educational Resources Information Center

    Farmer, Ernest

    1987-01-01

    Successful school bus drivers bring much more than mechanical know-how to the job. They develop good rapport with students while acting to bring undesirable student behavior under control. Drivers must also show an interest in students' welfare and have a good sense of humor. (MLH)

  3. A Survey of Computerized School Bus Routing.

    ERIC Educational Resources Information Center

    Richards, Thomas C.

    A review of significant activities in the area of computerized school bus routing is conducted. The various factors which contribute to the complexity of transporting students to and from school are first surveyed and, following this, the overall problem is formalized in terms of a system of nodes and links. An analysis of several routing systems

  4. Energy DataBus (Fact Sheet)

    SciTech Connect

    Not Available

    2013-07-01

    NREL has developed the Energy DataBus, an open-sourced software that collects massive amounts of energy-related data at second-to-second intervals; stores it in a massive, scalable database; and turns it into useful information.

  5. Bus Maintenance is a Sound Investment.

    ERIC Educational Resources Information Center

    American School Board Journal, 1981

    1981-01-01

    Preventive school bus maintenance to reduce long-term costs should include daily visual inspections by drivers, frequent checks by mechanics, and comprehensive inspections every 5,000 miles. Mechanics recommend checking tail lights, batteries, brakes, lug nuts, leaf springs, tail pipes, and exhaust pipe hangers. (RW)

  6. School Bus Accidents: Reducing Incidents and Injuries

    ERIC Educational Resources Information Center

    Mahoney, Daniel

    2009-01-01

    The number of children injured in nonfatal school bus accidents annually is more than double the number previously estimated. In Ohio alone, approximately 20,800 children younger than 18 were occupants of school buses that were involved in crashes in 2003 and 2004 (McGeehan 2007). Among those children, most had minor or no injuries. However, there…

  7. FUEL CELL BUS DEMONSTRATION IN MEXICO CITY

    EPA Science Inventory

    The report discusses the performance of a cull-size, zero-emission, Proton Exchange Membrane (PEM) fuel-cell-powered transit bus in the atmospheric environment of Mexico City. To address the air quality problems caused by vehicle emissions in Mexico City, a seminar on clean vehic...

  8. Mission Services Evolution Center Message Bus

    NASA Technical Reports Server (NTRS)

    Mayorga, Arturo; Bristow, John O.; Butschky, Mike

    2011-01-01

    The Goddard Mission Services Evolution Center (GMSEC) Message Bus is a robust, lightweight, fault-tolerant middleware implementation that supports all messaging capabilities of the GMSEC API. This architecture is a distributed software system that routes messages based on message subject names and knowledge of the locations in the network of the interested software components.

  9. Bus 54 -- Where are you? A school bus intelligent information system

    SciTech Connect

    Truett, L.F.; Moore, S.; Tonn, B.; Conley, T.

    1998-07-01

    Although major accidents involving school buses are rare (only about 0.3% of all fatal crashes since 1986 are classified as school-bus-related), even minor accidents and breakdowns cause a great deal of parental anxiety. The objective of this research is to design an efficient, cost-effective, accurate, and secure system that will track individual school buses and communicate appropriate information to the school system`s central administration unit, to the school transportation administrator, and to parents of children on the bus. The greatest benefit of the proposed information system is that parents and officials can always know the location and condition (these conditions would vary depending on the needs of a particular school system) of the school buses. In case of an accident or mechanical problem, when emergency crews are needed, they can be dispatched almost immediately with a good understanding of the problem and the exact location of the bus. In addition to being able to track the bus while the child is on board, parents will be able to determine the location of their child`s bus prior to its arrival in the morning in order to prevent the child from needing to wait outside in inclement weather. The information available to parents can also be expanded to include maps of limited routes (e.g., snow routes). Basically, the Bus 54 concept consists of a bus component and a central data processing unit. Each bus will be outfitted with a global positioning satellite (GPS) device, a wireless communication device, and wireless data communication service. The central data processing unit will receive and process information from the buses and provide information access to parents and officials via an Internet link.

  10. Numerical study of urban traffic flow with dedicated bus lane and intermittent bus lane

    NASA Astrophysics Data System (ADS)

    Zhu, H. B.

    2010-08-01

    Based on the cellular automaton traffic flow model and the concept of public transport priority, a two-lane traffic model with an intermittent bus lane is proposed and the properties of urban traffic flow are studied. The cases of traffic with a dedicated bus lane (DBL), an intermittent bus lane (IBL) and an ordinary two-lane traffic are simulated, and comparisons in the form of the fundamental diagrams and the velocity-density profiles are made between them. It is shown that the DBL has the advantage of freeing buses from traffic interference and also has the disadvantage of disrupting traffic, the IBL is more efficient in improving the bus flow than ordinary two-lane traffic and maintaining the car flow at a higher level at the same time than the DBL, while the ordinary two-lane traffic suppresses public transportation and is not advantageous in easing urban traffic congestion. Also it is indicated that the DBL is only appropriate for low traffic flow in a two-lane traffic system, and this limitation can be partly overcome by opening the bus lane to general traffic intermittently when the bus lane is not in use by buses.

  11. 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.

  12. Characteristics of rainfall queues for rain attenuation studies over radio links at subtropical and equatorial Africa

    NASA Astrophysics Data System (ADS)

    Alonge, Akintunde A.; Afullo, Thomas J.

    2014-08-01

    Attenuation due to precipitation remains an important design factor in the future deployment of terrestrial and earth-space communication radio links. Largely, there are concerted efforts to understand the dynamics of precipitation in attenuation occurrence at subtropical, tropical, and equatorial region of Africa. In this deliberate approach, rainfall spikes pertaining to rain cells are conceptualized as distinct rain spike traffic over radio links, by applying queueing theory concepts. The queue distributions at Durban (29°52'S, 30°58'E) and Butare (2°36'S, 29°44'E)—respectively, of subtropical and equatorial climates—are investigated from distrometer measurements. The data sets at both sites are observed over four rain regimes: drizzle, widespread, shower, and thunderstorm. The queue parameters of service time and inter-arrival of rain spikes traffic at both regions are found to be Erlang-k distributed (Ek) and exponentially distributed (M), respectively. It is established that the appearance of rain rates over radio links invariably follows a First Come, First Served (FCFS), multi-server (s), infinite queue, and semi-Markovian process, designated as M/Ek/s/∞/FCFS discipline. Modeled queue parameters at both regions are found to vary significantly over different regimes. However, these queue parameters over the entire data set suggest similar queue patterns at both sites. More importantly, power law relationships describing other queue-related parameters are formulated. The paper concludes by demonstrating an application of queueing theory for rainfall synthesis. The proposed technique will provide an alternative method of estimating rain cell sizes and rain attenuation over satellite and terrestrial links.

  13. 58. VIEW OF SIGNAL BUS SECTION NUMBER 2 LOCATED OVER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    58. VIEW OF SIGNAL BUS SECTION NUMBER 2 LOCATED OVER THE CONTROL ROOM MEZZANINE IN THE SIGNAL POWER CONDITIONING ROOM. BUS IS A HEAVY COPPER BAR APPROXIMATELY 1/2" BY 4" WHICH CONDUCTS POWER THROUGHOUT THE POWER PLANT. BUS ARE PROTECTED BY A BRICK AND SOAPSTONE HOUSING. OPENINGS FOR INSPECTION AND ACCESS WOULD NORMALLY BE PROTECTED BY GLASS DOORS. THE BUS WOULD BE SUPPORTED ON INSULATORS WITHIN THE BRICK CHAMBER. BUS WAS REMOVED AND SALVAGED WHEN THE STATION WAS ABANDONED. THE OBJECT IN THE TOP CENTER OF THE PHOTOGRAPH IS A POTENTIAL TRANSFORMER USED TO REDUCE BUS POTENTIAL OF 2200 VOLTS TO LOW VOLTAGES SAFE FOR USE IN CONTROL ROOM CIRCUITRY. POTENTIAL TRANSFORMERS ARE PRECISION DEVICES WHICH PRODUCE AN ACCURATE LOW VOLTAGE ANALOG OF THE HIGH VOLTAGE ON THE BUS. - New York, New Haven & Hartford Railroad, Cos Cob Power Plant, Sound Shore Drive, Greenwich, Fairfield County, CT

  14. 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.

  15. Performance analysis of a scheme for concurrency/synchronization using queueing network models

    SciTech Connect

    Almeida, V.A.F.; Dowdy, L.W.

    1986-12-01

    Queueing network models have been used extensively to analyze performance of computer systems. However, queueing network models with product form solutions are not directly applicable to systems that process programs with internal concurrency/synchronization. An exact solution of system systems is often not feasible because of its large state space. Approximation techniques, based on queueing network theory, are presented which analyze the performance of closed systems with a specific scheme of concurrency/synchronization. The techniques are applicable to multitasking systems, distributed database systems, packet routing environments, and fork/join situations.

  16. Exact dynamical state of the exclusive queueing process with deterministic hopping

    NASA Astrophysics Data System (ADS)

    Arita, Chikashi; Schadschneider, Andreas

    2011-11-01

    The exclusive queueing process (EQP) has recently been introduced as a model for the dynamics of queues that takes into account the spatial structure of the queue. It can be interpreted as a totally asymmetric exclusion process of varying length. Here we investigate the case of deterministic bulk hopping p=1 that turns out to be one of the rare cases where exact nontrivial results for the dynamical properties can be obtained. Using a time-dependent matrix product form we calculate several dynamical properties, e.g., the density profile of the system.

  17. Using simulation in out-patient queues: a case study.

    PubMed

    Huarng, F; Lee, M H

    1996-01-01

    Overwork and overcrowding in some periods was an important issue for the out-patient department of a local hospital in Chia-Yi in Taiwan. The hospital administrators wanted to manage the patient flow effectively. Describes a study which focused on the utilization of doctors and staff in the out-patient department, the time spent in the hospital by an out-patient, and the length of the out-patient queue. Explains how a computer simulation model was developed to study how changes in the appointment system, staffing policies and service units would affect the observed bottleneck. The results show that the waiting time was greatly reduced and the workload of the doctor was also reduced to a reasonable rate in the overwork and overcrowding periods. PMID:10162126

  18. Ultrasound waiting lists: rational queue or extended capacity?

    PubMed

    Brasted, Christopher

    2008-06-01

    The features and issues regarding clinical waiting lists in general and general ultrasound waiting lists in particular are reviewed, and operational aspects of providing a general ultrasound service are also discussed. A case study is presented describing a service improvement intervention in a UK NHS hospital's ultrasound department, from which arises requirements for a predictive planning model for an ultrasound waiting list. In the course of this, it becomes apparent that a booking system is a more appropriate way of describing the waiting list than a conventional queue. Distinctive features are identified from the literature and the case study as the basis for a predictive model, and a discrete event simulation model is presented which incorporates the distinctive features. PMID:18581826

  19. 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.

  20. Stochastic queueing-theory approach to human dynamics

    NASA Astrophysics Data System (ADS)

    Walraevens, Joris; Demoor, Thomas; Maertens, Tom; Bruneel, Herwig

    2012-02-01

    Recently, numerous studies have shown that human dynamics cannot be described accurately by exponential laws. For instance, Barabási [Nature (London)NATUAS0028-083610.1038/nature03459 435, 207 (2005)] demonstrates that waiting times of tasks to be performed by a human are more suitably modeled by power laws. He presumes that these power laws are caused by a priority selection mechanism among the tasks. Priority models are well-developed in queueing theory (e.g., for telecommunication applications), and this paper demonstrates the (quasi-)immediate applicability of such a stochastic priority model to human dynamics. By calculating generating functions and by studying them in their dominant singularity, we prove that nonexponential tails result naturally. Contrary to popular belief, however, these are not necessarily triggered by the priority selection mechanism.

  1. Exposure assessment of diesel bus emissions.

    PubMed

    Yip, Maricela; Madl, Pierre; Wiegand, Aaron; Hofmann, Werner

    2006-12-01

    The goal of this study was to measure ultrafine particle concentrations with diameters less than 1 mum emitted by diesel buses and to assess resulting human exposure levels. The study was conducted at the Woolloongabba Busway station in Brisbane, Australia in the winter months of 2002 during which temperature inversions frequently occurred. Most buses that utilize the station are fuelled by diesel, the exhaust of which contains a significant quantity of particle matter. Passengers waiting at the station are exposed to these particles emitted from the buses. During the course of this study, passenger census was conducted, based on video surveillance, yielding person-by-person waiting time data. Furthermore, a bus census revealed accurate information about the total number of diesel versus Compressed Natural Gas (CNG) powered buses. Background (outside of the bus station) and platform measurements of ultrafine particulate number size distributions were made to determine ambient aerosol concentrations. Particle number exposure concentration ranges from 10 and 40 to 60% of bus related exhaust fumes. This changes dramatically when considering the particle mass exposure concentration, where most passengers are exposed to about 50 to 80% of exhaust fumes. The obtained data can be very significant for comparison with similar work of this type because it is shown in previous studies that exhaust emissions causes cancer in laboratory animals. It was assumed that significant differences between platform and background distributions were due to bus emissions which, combined with passenger waiting times, yielded an estimate of passenger exposure to ultrafine particles from diesel buses. From an exposure point of view, the Busway station analyzed resembles a street canyon. Although the detected exhaust particle concentration at the outbound platform is found to be in the picogram range, exposure increases with the time passengers spend on the platform along with their breathing frequency. PMID:17159271

  2. Spacecraft design project multipurpose satellite bus MPS

    NASA Technical Reports Server (NTRS)

    Kellman, Lyle; Riley, John; Szostak, Michael; Watkins, Joseph; Willhelm, Joseph; Yale, Gary

    1990-01-01

    The thrust of this project was to design not a single spacecraft, but to design a multimission bus capable of supporting several current payloads and unnamed, unspecified future payloads. Spiraling costs of spacecraft and shrinking defense budgets necessitated a fresh look at the feasibility of a multimission spacecraft bus. The design team chose two very diverse and different payloads, and along with them two vastly different orbits, to show that multimission spacecraft buses are an area where indeed more research and effort needs to be made. Tradeoffs, of course, were made throughout the design, but optimization of subsystem components limited weight and volume penalties, performance degradation, and reliability concerns. Simplicity was chosen over more complex, sophisticated and usually more efficient designs. Cost of individual subsystem components was not a primary concern in the design phase, but every effort was made to chose flight tested and flight proven hardware. Significant cost savings could be realized if a standard spacecraft bus was indeed designed and purchased in finite quantities.

  3. 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.

  4. 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.

  5. Non-stationary analysis of queueing delay behavior in the GI/M/1/N-type queue with server working vacations

    NASA Astrophysics Data System (ADS)

    Kempa, Wojciech M.

    2015-11-01

    A finite-buffer GI/M/1/N-type queueing model with single working vacations is considered. Every time when the system becomes empty the server initializes an exponentially distributed single working vacation period, during which the processing of jobs is carried out with another (slower) rate. After finishing the vacation period the service process is being continued with normal (higher) speed. The next working vacation period is started at the next moment at which the queue empties and so on. The systems of integral equations for time-dependent queueing delay distributions, conditioned by the initial level of buffer saturation and related to each other, are built for systems beginning the operation in normal and working vacation modes, separately. The solutions for corresponding systems written for Laplace transforms are given explicitly using the linear algebraic approach.

  6. The design of serial communication in the queue system based on arm

    NASA Astrophysics Data System (ADS)

    Feng, Ansong; Ge, Xiaoyu; Wang, Qinghui

    2013-03-01

    In the paper, the serial communication in the queue system is discussed. Firstly the data send and receive is research and the routine diagram of send and receive is drawn up; secondly the data frame from main computer to end point is introduced; finally the realization of data process and data integrality is discussed. In all the paper, the realization process of the serial communication in the queue is described.

  7. 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.

  8. Communication design for multi-boards based on VME bus

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Song, Fazhi; Wei, Kai; Fu, Zhenxian

    2015-02-01

    As a widely used open-architecture computer bus ,VME bus is increasingly applied in military, aerospace, transportation and other large-scale control systems. Lithography, a very delicate and complicated integrated circuit manufacturing equipment, uses many circuit boards with VME interface in its control system, including one single-board computer, many movement control boards and one data acquisition board. This paper designs communication modules which include VME bus module and VME user-defined bus module for multi-boards in Lithography control system. VME bus module is designed for the communication between the single-board computer and movement control boards and VME user-defined bus is designed for the communication between movement control boards and data acquisition board. The experimental results demonstrate its effectiveness.

  9. IEEE 488 bus pseudo-controller linking talker with listener

    SciTech Connect

    Hale, G.M.

    1984-02-01

    A circuit is described that places talker/listener addresses on an IEEE 488 bus. This circuit is applied together with an ICS Electronics Corporation Model 4824 IEEE 488 Bus Serial Interface Card to permit a DEC VT (trademarks of Digital Equipment Corporation) 102 terminal to copy to a Commodore Model 2022 printer. The circuit takes the place of a controller to initiate the bus link. Command conflicts between the VT102 and the 2022 restrict the printer operation to the uppercase mode.

  10. TMS communications hardware. Volume 2: Bus interface unit

    NASA Technical Reports Server (NTRS)

    Brown, J. S.; Hopkins, G. T.

    1979-01-01

    A prototype coaxial cable bus communication system used in the Trend Monitoring System to interconnect intelligent graphics terminals to a host minicomputer is described. The terminals and host are connected to the bus through a microprocessor-based RF modem termed a Bus Interface Unit (BIU). The BIU hardware and the Carrier Sense Multiple Access Listen-While-Talk protocol used on the network are described.

  11. Emission inventory estimation of an intercity bus terminal.

    PubMed

    Qiu, Zhaowen; Li, Xiaoxia; Hao, Yanzhao; Deng, Shunxi; Gao, H Oliver

    2016-06-01

    Intercity bus terminals are hotspots of air pollution due to concentrated activities of diesel buses. In order to evaluate the bus terminals' impact on air quality, it is necessary to estimate the associated mobile emission inventories. Since the vehicles' operating condition at the bus terminal varies significantly, conventional calculation of the emissions based on average emission factors suffers the loss of accuracy. In this study, we examined a typical intercity bus terminal-the Southern City Bus Station of Xi'an, China-using a multi-scale emission model-(US EPA's MOVES model)-to quantity the vehicle emission inventory. A representative operating cycle for buses within the station is constructed. The emission inventory was then estimated using detailed inputs including vehicle ages, operating speeds, operating schedules, and operating mode distribution, as well as meteorological data (temperature and humidity). Five functional areas (bus yard, platforms, disembarking area, bus travel routes within the station, and bus entrance/exit routes) at the terminal were identified, and the bus operation cycle was established using the micro-trip cycle construction method. Results of our case study showed that switching to compressed natural gas (CNG) from diesel fuel could reduce PM2.5 and CO emissions by 85.64 and 6.21 %, respectively, in the microenvironment of the bus terminal. When CNG is used, tail pipe exhaust PM2.5 emission is significantly reduced, even less than brake wear PM2.5. The estimated bus operating cycles can also offer researchers and policy makers important information for emission evaluation in the planning and design of any typical intercity bus terminals of a similar scale. PMID:27220506

  12. 49 CFR 605.18 - Comments by private school bus operators.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Comments by private school bus operators. 605.18... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION SCHOOL BUS OPERATIONS School Bus Agreements § 605.18 Comments by private school bus operators. Private school bus operators may file written comments on an...

  13. The SMART MIL-STD-1553 bus adapter hardware manual

    NASA Technical Reports Server (NTRS)

    Ton, T. T.

    1981-01-01

    The SMART Multiplexer Interface Adapter, (SMIA) a complete system interface for message structure of the MIL-STD-1553, is described. It provides buffering and storage for transmitted and received data and handles all the necessary handshaking to interface between parallel 8-bit data bus and a MIL-STD serial bit stream. The bus adapter is configured as either a bus controller of a remote terminal interface. It is coupled directly to the multiplex bus, or stub coupled through an additional isolation transformer located at the connection point. Fault isolation resistors provide short circuit protection.

  14. Status of the IEEE P896 Future Backplane Bus

    SciTech Connect

    Gustavson, D.B.

    1983-10-01

    The IEEE P896 Future Backplane Bus project has been influenced by and has influenced FASTBUS and several other contemporary bus designs. This paper summarizes the current status of that project, which is directed toward the needs of modern 32-bit microprocessor systems with multiple processors. Some of the technology developed for P896 will be important for future non-ECL implementations of FASTBUS and other buses. In particular, new bus drivers and receivers should greatly improve the performance and reliability of backplane buses and cable buses. The current status of the P896 serial bus is also summarized.

  15. The SMART MIL-STD-1553 bus adapter hardware manual

    NASA Astrophysics Data System (ADS)

    Ton, T. T.

    1981-04-01

    The SMART Multiplexer Interface Adapter, (SMIA) a complete system interface for message structure of the MIL-STD-1553, is described. It provides buffering and storage for transmitted and received data and handles all the necessary handshaking to interface between parallel 8-bit data bus and a MIL-STD serial bit stream. The bus adapter is configured as either a bus controller of a remote terminal interface. It is coupled directly to the multiplex bus, or stub coupled through an additional isolation transformer located at the connection point. Fault isolation resistors provide short circuit protection.

  16. Managing Student Behavior on the School Bus: A Key to Bus Safety

    ERIC Educational Resources Information Center

    American Federation of Teachers (NJ), 2007

    2007-01-01

    School buses are the safest form of mass transit in America. Every day, school buses travel through congested city traffic and on isolated country roads in all types of weather, safely transporting millions of children to and from school and school-related activities. Federal and state standards for school bus construction and maintenance and…

  17. Redesign of Transjakarta Bus Driver's Cabin

    NASA Astrophysics Data System (ADS)

    Mardi Safitri, Dian; Azmi, Nora; Singh, Gurbinder; Astuti, Pudji

    2016-02-01

    Ergonomic risk at work stations with type Seated Work Control was one of the problems faced by Transjakarta bus driver. Currently “Trisakti” type bus, one type of bus that is used by Transjakarta in corridor 9, serving route Pinang Ranti - Pluit, gained many complaints from drivers. From the results of Nordic Body Map questionnaires given to 30 drivers, it was known that drivers feel pain in the neck, arms, hips, and buttocks. Allegedly this was due to the seat position and the button/panel bus has a considerable distance range (1 meter) to be achieved by drivers. In addition, preliminary results of the questionnaire using Workstation Checklist identified their complaints about uncomfortable cushion, driver's seat backrest, and the exact position of the AC is above the driver head. To reduce the risk level of ergonomics, then did research to design the cabin by using a generic approach to designing products. The risk analysis driver posture before the design was done by using Rapid Upper Limb Assessment (RULA), Rapid Entire Body Assessment (REBA), and Quick Exposure Checklist (QEC), while the calculation of the moment the body is done by using software Mannequin Pro V10.2. Furthermore, the design of generic products was done through the stages: need metric-matrix, house of quality, anthropometric data collection, classification tree concept, concept screening, scoring concept, design and manufacture of products in the form of two-dimensional. While the design after design risk analysis driver posture was done by using RULA, REBA, and calculation of moments body as well as the design visualized using software 3DMax. From the results of analysis before the draft design improvements cabin RULA obtained scores of 6, REBA 9, and the result amounted to 57.38% QEC and moment forces on the back is 247.3 LbF.inch and on the right hip is 72.9 LbF.in. While the results of the proposed improvements cabin design RULA obtained scores of 3, REBA 4, and the moment of force on the back is 90.3 LbF.in and on the right hip is 70.6 LbF.in. This indicated improvement cabin design can reduce ergonomic risk with lower scores on several parts of the body.

  18. Interface Provides Standard-Bus Communication

    NASA Technical Reports Server (NTRS)

    Culliton, William G.

    1995-01-01

    Microprocessor-controlled interface (IEEE-488/LVABI) incorporates service-request and direct-memory-access features. Is circuit card enabling digital communication between system called "laser auto-covariance buffer interface" (LVABI) and compatible personal computer via general-purpose interface bus (GPIB) conforming to Institute for Electrical and Electronics Engineers (IEEE) Standard 488. Interface serves as second interface enabling first interface to exploit advantages of GPIB, via utility software written specifically for GPIB. Advantages include compatibility with multitasking and support of communication among multiple computers. Basic concept also applied in designing interfaces for circuits other than LVABI for unidirectional or bidirectional handling of parallel data up to 16 bits wide.

  19. Spaceborne Fiber Optic Data Bus (SFODB)

    NASA Technical Reports Server (NTRS)

    Bretthauer, Joy W.; Chalfant, Chuck H.; Orlando, Fred J.; Parkerson, P.; Rezek, Ed; Sawyer, Marc

    1999-01-01

    Spaceborne Fiber Optic Data Bus (SFODB) is an IEEE 1393 compliant, gigabit per second, fiber optic network specifically designed to support the real-time, on-board data handling requirements of remote sensing spacecraft. The network is fault tolerant highly reliable, and capable of withstanding the rigors of launch and the harsh space environment. SFODB achieves this operational and environmental performance while maintaining the small size, light weight, and low power necessary for spaceborne applications. On December 9, 1998, SFODB was successfully demonstrated at NASA's Goddard Space Flight Center (GSFC).

  20. MIL-STD-1553 dual redundant remote terminal superhybrid

    NASA Astrophysics Data System (ADS)

    Friedman, S. N.

    This paper describes the performance, physical and electrical characteristics of the BUS-65112 Superhybrid, which performs as a fully compliant MIL-STD-1553 Dual Redundant Remote Terminal Unit (RTU). A discussion of the Custom Monolithic LSI components implemented in the Superhybrid is included. The RTU's special features and capabilities is highlighted, along with special programming options which facilitate a broad array of applications. The BUS-65112 Superhybrid contains all the necessary control lines to allow easy Direct Memory Access (DMA). The interface timing, operational philosophy, and a block diagram highlighting the Superhybrid's functional architecture are included.

  1. Weighted fair queueing scheduling for World Wide Web proxy servers

    NASA Astrophysics Data System (ADS)

    El Abdouni Khayari, Rachid; Sadre, Ramin; Haverkort, Boudewijn R.; Zoschke, Norman

    2002-07-01

    Current world-wide web servers as well as proxy servers rely for their scheduling on services provided by the underlying operating system. In practice, this means that some form of first-come-first-served (FCFS) scheduling is utilised. Although FCFS is a reasonable scheduling strategy for job sequences that do not show much variance, in the world-wide web (WWW), however, it has been shown that the typical object sizes requested do exhibit heavy tails. This means that the probability to observe very long jobs (very large objects) is much higher than typically predicted using an exponential model. Under these circumstances, job scheduling on the basis of shortest-job first (SJF) has been shown to perform much better, in fact, to minimise the total average waiting time, simply by avoiding situations in which short jobs have to wait for very long one. However, SJF has as disadvantage that long jobs might suffer from starvation. In order to avoid the problems of both FCFS and SJF we present in this paper a new scheduling algorithm called class-based interleaving weighted fair queueing (CI-WFQ). This algorithm uses the specific characteristics of the job stream being served, that is, the distribution of the sizes of the objects being requested, to set its parameters such that good mean reponse times are obtained and starvation does not occur. In the paper, the new scheduling approach is introduced and compared, using trace-driven simulations, with existing scheduling approaches.

  2. Preemptive queueing system with randomized push-out mechanism

    NASA Astrophysics Data System (ADS)

    Muliukha, Vladimir; Ilyashenko, Alexander; Zayats, Oleg; Zaborovsky, Vladimir

    2015-04-01

    In this article considered a queueing theory model with limited buffer size, one service channel, and two incoming flows. In this model one of the flows has a power to preempt other tasks. We call it a high-priority flow. Another one is low-priority. This priority mechanism is realized in a two different ways. The first one is a preemptive priority, which allows high-priority packets to interrupt low-priority packets in service channel and push them out. The second one is a randomized push-out mechanism with probability α, which allows us to choose what type of packets should be pushed out of the system when it is full. In this article we provide an algorithm for computing statistical characteristics of the model for all values of push-out probability α. We have used generating functions method to simplify the system of linear equations. This method allows us to reduce the order of linear equations system from k(k + 1)/2 to (k + 1). As the result we have got two effects in this model. The first one is a linear behavior of loss probabilities in the model with low overload. The second one is a "closing" of a system for low-priority packets with high overload.

  3. Passive solar heating of an electric bus

    SciTech Connect

    Duffy, J.; Reinhardt, M.; Chien, C.H.

    1996-11-01

    Existing heating systems in electric vehicles in cold climates result in loss in range with resistance heaters or air pollution with fossil fuel heaters. This study has as its goal the heating of an electric bus with almost no battery energy use and no fossil fuel in a climate similar to that of Boston with a design ambient temperature of 0 F ({minus}18 C). The author uses classic passive solar design strategies: minimize heat loss, use heat-recovery ventilators, add glazing layers to a large window area, and store heat in phase-change materials. The result is a solar/thermal management system which utilizes very little battery energy, has a cost which should be competitive with fossil-fuel and resistance heaters, has a small range impact, utilizes materials which have a lower environmental impact than battery materials and certainly fossil-fuel heaters, and should be convenient to use. The insulation and weatherization, heat recovery ventilators, extra glazings, and a prototype phase-change storage system have all been implemented on the first electric bus in New England/New York. Initial results are encouraging.

  4. A High Efficiency DC Bus Regulator / RPC for Spacecraft Applications

    NASA Astrophysics Data System (ADS)

    Birchenough, Arthur G.

    2004-02-01

    DC bus voltage regulation may be required in future high powered spacecraft due to the length of the busses or because they are not generated at precise voltage levels. In these cases the regulation range is often only a few percent increase or decrease, but conventional DC voltage regulators switch all the power passing through them, and this level of power switched determines the size and losses in the regulator. A recently developed concept uses a low power DC-DC converter in series with the bus to raise or lower the bus voltage over a small range. This partial power processing technique combines the small size and power losses of the low power converter with the ability to regulate, (over a small range) a high power bus. The Series Connected Buck Boost Regulator (SCBBR) described herein provides bus regulation with an efficiency of 98%. The circuit also provides bus switching and overcurrent limiting functions of a Remote Power Controller (RPC). This paper describes the circuit design and performance of a breadboard SCBBR configured as a bus voltage regulator providing +/- 40% voltage regulation range, bus switching, and overload limiting.

  5. 32 CFR 935.138 - Motor bus operation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 6 2014-07-01 2014-07-01 false Motor bus operation. 935.138 Section 935.138 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE TERRITORIAL AND INSULAR REGULATIONS WAKE ISLAND CODE Motor Vehicle Code § 935.138 Motor bus operation. Each person operating a...

  6. 32 CFR 935.138 - Motor bus operation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 6 2012-07-01 2012-07-01 false Motor bus operation. 935.138 Section 935.138 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE TERRITORIAL AND INSULAR REGULATIONS WAKE ISLAND CODE Motor Vehicle Code § 935.138 Motor bus operation. Each person operating a...

  7. Delay at signal-controlled intersection with bus stop upstream

    SciTech Connect

    Wong, S.C.; Yeung, W.S.A.; Cheuk, S.L.; Lo, M.K.; Yang, H.

    1998-05-01

    Because of the tight constraints on many streets in urban areas, it is not uncommon to situate a bus stop upstream of a signal-controlled intersection without the provision of a proper bus bay or setback. For a single-lane approach, where the overtaking of a stopped bus at the bus stop is prohibited, the setup of such a bus stop would significantly affect the delay incurred by road users. It is believed that the delay in such situations depends on a number of factors, such as the distance between bus stop and stop line, traffic and bus flows, dwell time of buses and signal settings. In this paper, a simulation model for estimating the delay on an approach to a signal-controlled intersection with a bus stop upstream is developed. To test the reliability of the model, field surveys were conducted to validate the simulation model. A good agreement between the observed and simulation results was obtained. When the simulation model was used, a new delay formula was established and calibrated for use in the design of a signal-controlled intersection.

  8. School Bus Driver Instructional Program. Instructor's Guide--Advanced Unit.

    ERIC Educational Resources Information Center

    Department of Transportation, Washington, DC. National Highway Safety Bureau.

    Geared to behavioral objectives, the instruction is organized into programed units on emergency driving techniques, first aid, field trips, transporting exceptional students, detecting hazards, controlling the position of the bus, driving under special conditions, and preventive maintenance of the bus. Each unit is constructed around content

  9. 16. Bus Room (also known as Switch Gear Room), view ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. Bus Room (also known as Switch Gear Room), view to the southeast. An air circuit breaker compressor (visible in photograph number 2) was once attached to the main bus relay visible in the background of the photograph. - Washington Water Power Clark Fork River Cabinet Gorge Hydroelectric Development, Powerhouse, North Bank of Clark Fork River at Cabinet Gorge, Cabinet, Bonner County, ID

  10. Oregon School Bus Drivers Training Program. Students Handbook. Core Course.

    ERIC Educational Resources Information Center

    Oregon State Dept. of Education, Salem.

    This student handbook is one of the publications used for the Oregon Bus Driver Training Core Course. Handbook content focuses on those aspects of driving a school bus that differ from driving an automobile and that are essential for the safe transporting of students. Designed to accompany the four classes (each two and one-half hours long), the…

  11. Riding the Bus: Symbol and Vehicle for Boundary Spanning

    ERIC Educational Resources Information Center

    Romero, Deborah

    2014-01-01

    In this reflective essay I examine the activity of a bus tour, organized as the result of an ongoing university and city partnership. I illustrate how riding the bus is not only symbolic for positionality in our society, but also how it can be a viable mechanism for initiating boundary spanning and promoting opportunities for place-based learning…

  12. Connecticut Transit (CTTRANSIT) Fuel Cell Transit Bus: Preliminary Evaluation Results

    SciTech Connect

    Chandler, K.; Eudy, L.

    2008-10-01

    This report provides preliminary results from a National Renewable Energy Laboratory evaluation of a protoptye fuel cell transit bus operating at Connecticut Transit in Hartford. Included are descriptions of the planned fuel cell bus demonstration and equipment; early results and agency experience are also provided.

  13. Network Extender for MIL-STD-1553 Bus

    NASA Technical Reports Server (NTRS)

    Marcus, Julius; Hanson, T. David

    2003-01-01

    An extender system for MIL-STD-1553 buses transparently couples bus components at multiple developer sites. The bus network extender is a relatively inexpensive system that minimizes the time and cost of integration of avionic systems by providing a convenient mechanism for early testing without the need to transport the usual test equipment and personnel to an integration facility. This bus network extender can thus alleviate overloading of the test facility while enabling the detection of interface problems that can occur during the integration of avionic systems. With this bus extender in place, developers can correct and adjust their own hardware and software before products leave a development site. Currently resident at Johnson Space Center, the bus network extender is used to test the functionality of equipment that, although remotely located, is connected through a MILSTD- 1553 bus. Inasmuch as the standard bus protocol for avionic equipment is that of MIL-STD-1553, companies that supply MIL-STD-1553-compliant equipment to government or industry and that need long-distance communication support might benefit from this network bus extender

  14. Application of CAN-bus Network in Intelligent parking

    NASA Astrophysics Data System (ADS)

    Jianjun, WU; Juan, Hu

    Convenient life makes intelligent parking every- where. This paper describes how to connect the various separate modern terminal of intelligent parking with CAN-bus network, and the competitive advantage of the system by using the CAN-bus network. From a technical point of view, this paper describes the development trend of intelligent parking in next few years.

  15. 32 CFR 935.138 - Motor bus operation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 6 2011-07-01 2011-07-01 false Motor bus operation. 935.138 Section 935.138 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE TERRITORIAL AND INSULAR REGULATIONS WAKE ISLAND CODE Motor Vehicle Code § 935.138 Motor bus operation. Each person operating a...

  16. 32 CFR 935.138 - Motor bus operation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Motor bus operation. 935.138 Section 935.138 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE TERRITORIAL AND INSULAR REGULATIONS WAKE ISLAND CODE Motor Vehicle Code § 935.138 Motor bus operation. Each person operating a...

  17. Bus-based best-practice and urban transport emissions

    NASA Astrophysics Data System (ADS)

    Enoch, Marcus Paul

    In Britain over recent years, transport has risen to the very top of the political agenda, partly because it is the fastest growing source of urban emissions. One politically attractive solution to this rapidly worsening problem, is 'improving public transport'. This thesis examines how the bus-the most widespread form of public transport-could be improved, and at how much these improvements would contribute to solving the emissions problem. The project was studied in two inter-related parts. The first part aimed to determine the factors necessary in forming the 'best possible' bus-based transport system by identifying and analysing a number of 'best-practice' bus systems in Europe and North America, using a case study approach. The second part then sought to quantify the effect on travel patterns and emissions that implementing this best possible bus-based transport system would have. This was done by modelling a series of possible scenarios with the START strategic transport model, and a modified version of the JET emissions inventory model. The City of Leicester was used as a modelling base. The study found that bus systems contributed most to reducing urban emissions where the needs of the bus passenger were made paramount, and where bus operators worked together with local government, local businesses etc. Even where these factors existed however, the effect of bus-based transport policies on levels of pollutants was found to be significant only when applied together with strong car restraint measures.

  18. Unreliable bulk retrial queues with delayed repairs and modified vacation policy

    NASA Astrophysics Data System (ADS)

    Jain, Madhu; Bhagat, Amita

    2014-06-01

    The present investigation deals with the bulk arrival M/G/1 retrial queue with impatient customers and modified vacation policy. The incoming customers join the virtual pool of customers called orbit if they find the server being busy, on vacation or in broken down state otherwise the service of the customer at the head of the batch is started by the server. The service is provided in k essential phases to all the customers by the single server which may breakdown while rendering service to the customers. The broken down server is sent to a repair facility wherein the repair is performed in d compulsory phases. As soon as the orbit becomes empty, the server goes for vacation and takes at most J vacations until at least one customer is noticed. The incoming customers are impatient and may renege on seeing a long queue of the customers for the service. The probability generating functions and queue length for the number of customers in the orbit and queue have been obtained using supplementary variable technique. Various system characteristics viz. average number of customers in the queue and the orbit, long run probabilities of the system states, etc. are obtained. Furthermore, numerical simulation has been carried out to study the sensitivity of various parameters on the system performance measures by taking an illustration.

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

    SciTech Connect

    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.

  20. Managing target of opportunity (ToO) observations in queue mode at Gemini Observatory

    NASA Astrophysics Data System (ADS)

    Roth, Katherine C.; Carrasco, E. Rodrigo; Miller, Bryan W.; Stephens, Andrew W.; Jørgensen, Inger; Rodgers, Bernadette

    2010-07-01

    Target of opportunity observations (ToO) are an integral part of multi-instrument queue operations at Gemini Observatory. ToOs comprise a significant fraction of the queue (20-25% of the highest ranking band) and with the advent of large survey telescopes (eg. Pan-STARRS, LSST) dedicated to searching for transient events this fraction may reasonably be expected to increase significantly in the coming years. While some important aspects of ToO execution at Gemini Observatory are managed automatically (eg. trigger alerts, data distribution), other areas such as duplications checking, scheduling and relative priority determination still require manual intervention. In order to increase efficiency and improve our commitment to ToOs and queue observing in general, these aspects need to be formalized and incorporated into improved phase 2 checking, automated queue scheduling and on-the-fly nightly plan generation software. We discuss the different flavors of ToOs supported at Gemini Observatory and how each kind is scheduled with respect to existing queue observations. We present ideas for formalizing these practices into a system of dynamical prioritization which automatically self adjusts as new ToO observations are triggered, high priority targets become endangered, and timing windows near expiration.

  1. Method and systems for a radiation tolerant bus interface circuit

    NASA Technical Reports Server (NTRS)

    Kinstler, Gary A. (Inventor)

    2007-01-01

    A bus management tool that allows communication to be maintained between a group of nodes operatively connected on two busses in the presence of radiation by transmitting periodically a first message from one to another of the nodes on one of the busses, determining whether the first message was received by the other of the nodes on the first bus, and when it is determined that the first message was not received by the other of the nodes, transmitting a recovery command to the other of the nodes on a second of the of busses. Methods, systems, and articles of manufacture consistent with the present invention also provide for a bus recovery tool on the other node that re-initializes a bus interface circuit operatively connecting the other node to the first bus in response to the recovery command.

  2. Thermal analysis of the SMES ETM power bus cryostat

    SciTech Connect

    Daly, E.F.; Kupiszewski, T.; Christianson, O.R.

    1994-12-31

    In order to ensure reliable operation of the Superconducting Magnet Energy Storage Engineering Test Model (SMES-ETM), the conductor in the power bus must meet similar performance requirements as the entire coil during both steady state and transient operating modes. Lumped parameter thermal analyses are performed to evaluate steady state performance and assess risk involved with failure modes associated with the superconducting bus cryostat. Transient heat fluxes to the superfluid helium vessel are calculated for the loss of bus vacuum and the loss of nitrogen shroud cooling. The elapsed time to reach the critical heat flux in superfluid helium is calculated using the heat conductivity function for these cases. It is concluded that in the event of bus cooling failure, barring catastrophic loss of vacuum, the bus and cryostat can function for limited periods of time without interrupting ETM operations.

  3. Mechanical and embedded systems design for Generic Nanosatellite Bus spacecraft

    NASA Astrophysics Data System (ADS)

    Armitage, Scott Edward

    The adaptation of the University of Toronto Space Flight Laboratory Generic Nanosatellite Bus (GNB) mechanical design to Earth-observation and communications applications is investigated. The ability of this bus to expand the capabilities of low-cost nanosatellites by accommodating large pre-deployed payload appendages, such as antennas, is demonstrated. In addition, the operational architecture of a cold-gas nanosatellite propulsion system, enabling small satellite constellations and formation flying, is described. Component testing of this system has validated compliance with subsystem requirements. Lastly, the design and development of a multi-mission embedded systems generic firmware is described. This firmware consolidates common and critical software functionality, greatly reducing both the risk and cost of developing software for new embedded systems. The firmware has been designed for a distributed-node microcontroller bus architecture in general, and the Nanosatellite for Earth Monitoring and Observation (NEMO) bus and Generic Nanosatellite Bus in particular.

  4. Genetic algorithm for multiple bus line coordination on urban arterial.

    PubMed

    Yang, Zhen; Wang, Wei; Chen, Shuyan; Ding, Haoyang; Li, Xiaowei

    2015-01-01

    Bus travel time on road section is defined and analyzed with the effect of multiple bus lines. An analytical model is formulated to calculate the total red time a bus encounters when travelling along the arterial. Genetic algorithm is used to optimize the offset scheme of traffic signals to minimize the total red time that all bus lines encounter in two directions of the arterial. The model and algorithm are applied to the major part of Zhongshan North Street in the city of Nanjing. The results show that the methods in this paper can reduce total red time of all the bus lines by 31.9% on the object arterial and thus improve the traffic efficiency of the whole arterial and promote public transport priority. PMID:25663837

  5. Characterizing bus transit passenger wait times. Research report

    SciTech Connect

    Salek, M.D.; Machemehl, R.B.

    1999-06-01

    Mathematical models are developed to predict bus passenger waiting time components. A statistically significant quantity of waiting time data, including related passenger attributes, transits system characteristics and bus frequency, were collected by direct observation and video taping. The experimental data were collected in a six-month period at several bus transfer centers and bus stations in the city of Austin, Texas. Measured wait time was decomposed into two components: `wait time before scheduled departure time` and `wait time after scheduled departure time.` The effects of bus frequency and reliability, as well as other potential predictors on wait time components, were examined by performing Analysis of Variance and Regression. Traditional and conceptual waiting time models were evaluated using this data set and compared to the new developed models.

  6. The Fairchild MIL-STD-1553 Serial Multiplex Bus Tester

    NASA Astrophysics Data System (ADS)

    Dunn, A. M.

    The Fairchild Serial Multiplex Bus Tester (SMBT) is a general purpose computer controlled MIL-STD-1553 stimulus/response/analyzer. SMBT has been selected to fulfill the data bus testing requirements of the Air Force Modular Automatic Test Equipment (MATE) systems. The design is three separate devices or functions: a monitor, a bus controller, and a remote terminal simulator, which may be operated in any combination. The purpose is to integrate the Monitor, Controller, and Remote Terminal functions into a single unit. SMBT may be controlled and synchronized by a master computer performing a coordinated total checkout of a unit under test. The monitor allows a collection of 1024 word 'windows' of bus traffic and simultaneously accumulate error statistics in all bus traffic. A system self check is incorporated as an additional feature of the design. In summary, the SMBT is designed to provide necessary stimulus, response and analysis capability for MIL-STD-1553 Line Replaceable Unit (LRU) testing.

  7. The M/G/1 retrial queue: New descriptors of the customer's behavior

    NASA Astrophysics Data System (ADS)

    Amador, J.; Artalejo, J. R.

    2009-01-01

    We consider queuing systems where customers are not allowed to queue; instead of that they make repeated attempts, or retrials, in order to enter service after some time. The performance of telephone systems and communication networks modelled as retrial queues differs from standard waiting lines because typically the retrial group is an invisible queue which cannot be observed. As a result, the original flow of primary arrivals and the flow of repeated attempts become undistinguished. Our aim in this paper is to consider some aspects of this problem. Thus, we focus on the main retrial model of M/G/1 type and investigate the distribution of the successful and blocked events made by the primary customers and the retrial customers.

  8. Stochastic ordering properties and optimal routing control for a class of finite capacity queueing systems

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    The problem of routing jobs to parallel queues with identical exponential servers and unequal finite buffer capacities is considered. Stochastic ordering and weak majorization properties on critical performance measures are established by means of event-driven inductions. In particular, it is shown that the intuitive 'join the shortest non-full queue' (SNQ) policy is optimal with respect to an overall function that accounts for holding and blocking costs. Moreover, the buffer allocation problem is solved by proving the intuitive result that, for a fixed total buffer capacity, 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. A GA-based PID active queue management control design for TCP/IP networks

    NASA Astrophysics Data System (ADS)

    Kuo, H.-H.; Chen, C.-K.; Yan, J.-J.; Liao, T.-L.

    2008-02-01

    In this paper, a genetic algorithm-based (GA-based) proportional-integral-derivative (PID) controller as an active queue manager for Internet routers is proposed to reduce packet loss and improve network utilization in TCP/IP networks. Based on the window-based nonlinear dynamics, the TCP network was modeled as a time-delayed system with a saturated input due to the limitations of packet-dropping probability and the effects of propagation delays in TCP networks. An improved genetic algorithm is employed to derive optimal or near optimal PID control gains such that a performance index of integrated-absolute error (IAE) in terms of the error between the router queue length and the desired queue length is minimized. The performance of the proposed control scheme was evaluated in various network scenarios via a series of numerical simulations. The simulation results confirm that the proposed scheme outperforms other AQM schemes.

  10. 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. PMID:21963108

  11. Middleware for Processing Message Queues with Elasticity Support and Sequential Integrity of Asynchronous Message Processing

    NASA Astrophysics Data System (ADS)

    Henrique Teixeira, Eduardo; Patrícia Favacho de Araújo, Aletéia

    2015-10-01

    Elasticity in computing refers to dynamically adjusting the amount of allocated resources to process a distributed application. In order to achieve this, mechanisms are needed to avoid the phenomenon of the elasticity threshold detection moving constantly up or down. The existing work fails to deliver sequential integrity of asynchronous messages processing and the asymmetries of data distribution to achieve parallel consumption. This paper fills this gaps and proposes a middleware solution to dynamically analyze the flow of message queue, and a mechanism to increase the parallelized consumption based on the output behavior. An architecture for IOD (Increase On Demand) middleware is presented, with support for the increase and decrease of thread's to cope with the growth of message queues, using the technique of limit-based heuristics over a given period of time and grouping messages into sub-queues based on classification criteria.

  12. 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.

  13. Bus industry market study. Report -- Task 3.2: Fuel cell/battery powered bus system

    SciTech Connect

    Zalbowitz, M.

    1992-06-02

    In support of the commercialization of fuel cells for transportation, Georgetown University, as a part of the DOE/DOT Fuel Cell Transit Bus Program, conducted a market study to determine the inventory of passenger buses in service as of December, 1991, the number of buses delivered in 1991 and an estimate of the number of buses to be delivered in 1992. Short term and long term market projections of deliveries were also made. Data was collected according to type of bus and the field was divided into the following categories which are defined in the report: transit buses, school buses, commercial non-transit buses, and intercity buses. The findings of this study presented with various tables of data collected from identified sources as well as narrative analysis based upon interviews conducted during the survey.

  14. The Wheels on the Bus Go “Buy Buy Buy”: School Bus Advertising Laws

    PubMed Central

    2012-01-01

    School buses, a practical necessity for millions of children, are at the center of new efforts to raise revenue. School bus advertising laws bring public health and commercialization concerns to the school setting. In doing so, they potentially expose school districts to First Amendment lawsuits. I examined various school bus advertising bills and laws. I reviewed First Amendment “forum analysis” as applied in the transit and school settings to clarify how this legal test may affect school districts subject to such laws. I have made recommendations for school districts to enact appropriate policies to ensure that such advertising does not undermine public health and to enable the districts to maintain control over their property. PMID:22742065

  15. Using field bus for optical gas monitoring

    NASA Astrophysics Data System (ADS)

    Cheng, Xiangyin; Seah, Leong K.; Ong, Lin S.; Asundi, Anand K.

    1999-05-01

    This paper presents a proposal for an optical gas monitoring system based on fieldbus. With the help of the advanced signal processing system more than one hundred gas detectors can be connected to a host system by a single shared bus cable over which the gas detectors, now incorporating with their own intelligence, communicate digitally with the host system. The new system supplies not only about the gas level but also about the physical condition of each sensor. Planed maintenance can be performed to ensure that gas monitor system is maintained in full working order. Integrating fieldbus with optical gas sensor will also have dramatic saving in field wiring and the man-hours for system verification and configuration.

  16. Status of the FASTBUS standard data bus

    SciTech Connect

    Larsen, R.S.

    1980-11-01

    FASTBUS is a new laboratory standard data bus intended for use in experimental data acquisition and control. The development of FASTBUS began with a feasibility study in 1976, and is presently at the development prototyping stage. The principal aims of the standard are to provide a factor of ten or more improvement in speed of data transfers over present systems, as well as to provide an architecture for systems containing multiple processors. Developmental prototypes now in progress include crates, backplanes, cooling devices, power supplies, test and diagnostic modules, and user modules. A sizeable software development effort is also underway. Several experiments have made commitments to use FASTBUS. A review of current work and potential applications is given. 10 figures.

  17. Bus bar electrical feedthrough for electrorefiner system

    DOEpatents

    Williamson, Mark; Wiedmeyer, Stanley G; Willit, James L; Barnes, Laurel A; Blaskovitz, Robert J

    2013-12-03

    A bus bar electrical feedthrough for an electrorefiner system may include a retaining plate, electrical isolator, and/or contact block. The retaining plate may include a central opening. The electrical isolator may include a top portion, a base portion, and a slot extending through the top and base portions. The top portion of the electrical isolator may be configured to extend through the central opening of the retaining plate. The contact block may include an upper section, a lower section, and a ridge separating the upper and lower sections. The upper section of the contact block may be configured to extend through the slot of the electrical isolator and the central opening of the retaining plate. Accordingly, relatively high electrical currents may be transferred into a glovebox or hot-cell facility at a relatively low cost and higher amperage capacity without sacrificing atmosphere integrity.

  18. 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.

  19. Chaotic queue-based genetic algorithm for design of a self-tuning fuzzy logic controller

    NASA Astrophysics Data System (ADS)

    Saini, Sanju; Saini, J. S.

    2012-11-01

    This paper employs a chaotic queue-based method using logistic equation in a non-canonical genetic algorithm for optimizing the performance of a self-tuning Fuzzy Logic Controller, used for controlling a nonlinear double-coupled system. A comparison has been made with a standard canonical genetic algorithm implemented on the same plant. It has been shown that chaotic queue-method brings an improvement in the performance of the FLC for wide range of set point changes by a more profound initial population spread in the search space.

  20. Rethinking passive transport: bus fare exemptions and young people's wellbeing.

    PubMed

    Jones, Alasdair; Steinbach, Rebecca; Roberts, Helen; Goodman, Anna; Green, Judith

    2012-05-01

    Much recent public health research has emphasised the health impacts for young people of 'active travel' modes, typically defined as walking and cycling. Less research has focused on public transport modes. Drawing on qualitative data, we examine the links between bus travel and wellbeing in London, where young people currently have free bus travel. Our findings indicate that bus travel can be both a physically and socially active experience for young people. We suggest a more nuanced understanding of 'active travel' is now needed, alongside greater attention to urban public transport networks as key sites that impact on important determinants of wellbeing such as independent mobility and social inclusion. PMID:22321902

  1. Apollo 14 mission: Inability to disconnect main bus A

    NASA Technical Reports Server (NTRS)

    1971-01-01

    During entry, the Apollo 14 spacecraft busses should have de-energized when the main bus-tie motor switches were switched to the off position. One motor switch did not transfer and main bus A remained energized until the battery bus-tie circuit breakers were opened after landing. Analysis revealed that residual catalyst caused the terminal pin seals to revert to a gummy state. Resulting reversion products then migrated to the motor commutator and caused brush degradation, increased and erratic commutator resistance, and reduced motor torque. The motor stalled when available motor torque was reduced below that required to drive through the maximum torque point of the switch.

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

    DOEpatents

    Chen, Dong; Gara, Alana; Heidelberger, Philip; Kumar, Sameer; Ohmacht, Martin; Steinmacher-Burow, Burkhard; Wisniewski, Robert

    2014-09-16

    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.

  3. Design of a Tree-Queue Model for a Large-Scale System

    NASA Astrophysics Data System (ADS)

    Park, Byungsung; Yoo, Jaeyeong; Kim, Hagbae

    In a large queuing system, the effect of the ratio of the filled data on the queue and waiting time from the head of a queue to the service gate are important factors for process efficiency because they are too large to ignore. However, many research works assumed that the factors can be considered to be negligible according to the queuing theory. Thus, the existing queuing models are not applicable to the design of large-scale systems. Such a system could be used as a product classification center for a home delivery service. In this paper, we propose a tree-queue model for large-scale systems that is more adaptive to efficient processes compared to existing models. We analyze and design a mean waiting time equation related to the ratio of the filled data in the queue. Based on simulations, the proposed model demonstrated improvement in process-efficiency, and it is more suitable to realistic system modeling than other compared models for large-scale systems.

  4. A standard interface for debugger access to message queue information in MPI.

    SciTech Connect

    Cownie, J.; Gropp. W.

    1999-06-25

    This paper discusses the design and implementation of an interface that allows a debugger to obtain the information necessary to display the contents of the MPI message queues. The design has been implemented in the TotalView debugger, and dynamic libraries that conform to the interface exist for MPICH, as well as the proprietary MPI implementations from Compaq, IBM, and SGI.

  5. 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.

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

    SciTech Connect

    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) 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.

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

    DOE PAGESBeta

    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

  8. 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…

  9. 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

  10. 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. PMID:24125314

  11. 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. PMID:26414758

  12. In-trail dynamics of multiple CDTI-equipped aircraft queues

    NASA Technical Reports Server (NTRS)

    Kelly, J. R.; Abbott, T. S.

    1984-01-01

    One of the potential problems of in-trail self-spacing with a Cockpit Display of Traffic Information (CDTI) is whether dynamic oscillations would occur in a queue of aircraft flying an approach, similar to the ""accordion'' effect seem with the queue of automobiles in stop-and-go traffic. In order to gain some insight into this potential problem, a brief experiment was conducted with the Transport Systems Research Vehicle (TSRV) ground-based simulator equipped with CDTI which presented the position of other aircraft in the area. Three simulation sessions were conducted wherein queues of up to nine aircraft were built, each one self-spacing on the preceding aircraft. The aircraft crews were rotated to ensure that the pilots had no prior knowledge of the lead aircraft behavior they would be following. Two different spacing criteria were employed: a constant time predictor criterion and a constant time delay criterion. The experiment failed to uncover any dynamic oscillatory tendencies in queues of seven to nine aircraft.

  13. 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.

  14. DATADRAW: A Command Language for Manipulating and Displaying Stacks, Queues, Lists and Trees.

    ERIC Educational Resources Information Center

    Siklossy, L.; And Others

    DATADRAW is a command language, written in FORTRAN IV, to manipulate stacks, queues, lists and trees, and to display them on the CDC 252 scope system attached to a CDC 6600. A DATADRAW primer is given, and the algorithms for updating and displaying structures are described. It is noted that DATADRAW was designed to be a simple command language…

  15. Rfid-Based Automatic Bus Ticketing: Features and Trends

    NASA Astrophysics Data System (ADS)

    Oudah, A.

    2016-02-01

    Recent advancements in various technologies have made remarkable developments in various fields for public welfare and public transport is one such area. In the near future public bus transport system with advanced technologies like Radio Frequency Identification Device (RFID), GSM, GPS, ZigBee and RF modules will gain spotlight due to their advantage of higher convenience and greater life standards as compared to the conventional bus systems. In this paper, a comprehensive review of all several proposed bus ticketing and bus information methods has been presented in detail. The study brings out improved solution in terms of cost, convenience, user satisfaction and future implementation. The choice of working modules and their efficient performance has been discussed along with the highlighted importance of the need of technology for welfare of common public and visually impaired.

  16. Analysis of Feeder Bus Network Design and Scheduling Problems

    PubMed Central

    Almasi, Mohammad Hadi; Karim, Mohamed Rehan

    2014-01-01

    A growing concern for public transit is its inability to shift passenger's mode from private to public transport. In order to overcome this problem, a more developed feeder bus network and matched schedules will play important roles. The present paper aims to review some of the studies performed on Feeder Bus Network Design and Scheduling Problem (FNDSP) based on three distinctive parts of the FNDSP setup, namely, problem description, problem characteristics, and solution approaches. The problems consist of different subproblems including data preparation, feeder bus network design, route generation, and feeder bus scheduling. Subsequently, descriptive analysis and classification of previous works are presented to highlight the main characteristics and solution methods. Finally, some of the issues and trends for future research are identified. This paper is targeted at dealing with the FNDSP to exhibit strategic and tactical goals and also contributes to the unification of the field which might be a useful complement to the few existing reviews. PMID:24526890

  17. Analysis of feeder bus network design and scheduling problems.

    PubMed

    Almasi, Mohammad Hadi; Mirzapour Mounes, Sina; Koting, Suhana; Karim, Mohamed Rehan

    2014-01-01

    A growing concern for public transit is its inability to shift passenger's mode from private to public transport. In order to overcome this problem, a more developed feeder bus network and matched schedules will play important roles. The present paper aims to review some of the studies performed on Feeder Bus Network Design and Scheduling Problem (FNDSP) based on three distinctive parts of the FNDSP setup, namely, problem description, problem characteristics, and solution approaches. The problems consist of different subproblems including data preparation, feeder bus network design, route generation, and feeder bus scheduling. Subsequently, descriptive analysis and classification of previous works are presented to highlight the main characteristics and solution methods. Finally, some of the issues and trends for future research are identified. This paper is targeted at dealing with the FNDSP to exhibit strategic and tactical goals and also contributes to the unification of the field which might be a useful complement to the few existing reviews. PMID:24526890

  18. How to Reduce Those Costly School Bus Accidents.

    ERIC Educational Resources Information Center

    Farmer, Ernest

    1985-01-01

    The deterrent to school bus accidents is preparedness. Training programs for drivers and mechanics, equipment specifications, and a community support base are some of the ways to prevent tragedy. (MLF)

  19. Spin-bus concept of spin quantum computing

    SciTech Connect

    Mehring, Michael; Mende, Jens

    2006-05-15

    We present a spin-bus concept of quantum computing where an electron spin S=1/2 acts as a bus qubit connected to a finite number N of nuclear spins I=1/2 serving as client qubits. Spin-bus clusters are considered as local processing units and may be interconnected with other spin-bus clusters via electron-electron coupling in a scaled up version. Here we lay the ground for the basic functional unit with long qubit registers, provide the theory and experimental verification of correlated qubit states, and demonstrate the Deutsch algorithm. Experiments were performed on a qubyte plus one nuclear spin in a solid state system.

  20. View of the current distribution "bus" atop switching cabinets within ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of the current distribution "bus" atop switching cabinets within the former transformer building. Looking northwest - Childs-Irving Hydroelectric Project, Childs System, Childs Powerhouse, Forest Service Road 708/502, Camp Verde, Yavapai County, AZ

  1. How incentives for bus use solved parking problems.

    PubMed

    Lefert, G W; Barney, S M

    1979-03-01

    St. Marys Hospital Medical Center, Madison, WI, solved its problem of limited parking space by subsidizing city bus passes and establishing a shuttle service between a peripheral parking lot and the hospital. PMID:761899

  2. Design of Wiring Structure by Considering Bus Bar Inductance

    NASA Astrophysics Data System (ADS)

    Ando, Masato; Wada, Keiji

    Recently, high-switching-frequency and high-di/dt switching operation of inverters has been studied for the purpose of finding a way to reduce the size and weight of LC filters. In power electronic circuits, the stray inductance of the bus bar between a DC capacitor and power devices may cause an overshoot voltage and electromagnetic interference (EMI) noise for high-di/dt switching operation. Therefore, it is necessary to design the bus bar structure while considering the minimization and optimization of the bus bar inductance value. Generally, the bus bar inductance is analyzed by using 3D finite element method (FEM), but it takes a long time to construct analytical models and to perform the analysis. This paper proposes an improved calculation method for a medium-voltage inverter, based on the partial inductance calculation method. In addition, the wiring structure is designed by considering the stray inductance with using an inductance-mapping method.

  3. CFD Investigation on Long-Haul Passenger Bus

    NASA Astrophysics Data System (ADS)

    Tan, C. F.; Tee, B. T.; Law, H. C.; Lim, T. L.

    2015-09-01

    Air flow distribution is one of the important factors that will influence the bus passenger comfort during long haul travel. Poor air flow distribution not only cause discomfort to the bus passenger but also influence their travel mode as well. The main purpose of this study is to investigate the air flow performance of the bus air-conditioning system through CFD simulation approach. A 3D CAD model of air ducts was drawn and hence analysed by using CFD software, namely ANSYS Fluent, to determine the airflow rate for every outlets of the air-conditioning system. The simulated result was then validated with experimental data obtained from prototype model of air duct. Based on the findings, new design concepts is proposed with the aim to meet the industry requirement as well as to improve the bus passenger comfort during long haul travel.

  4. Solar bus regulator and battery charger for IMP's H, I, and J

    NASA Technical Reports Server (NTRS)

    Paulkovich, J.

    1972-01-01

    Interplanetary Monitoring Probe (IMP) spacecrafts H, I, and J utilize a direct energy transfer (DET) type of power system operating from a solar array source. A shunt type of regulator prevents the bus voltage from exceeding a preset voltage level. The power system utilizes a single differential amplifier with dual outputs to control the battery charge/shunt regulator and the discharge regulator. A two-voltage level, current limited, series charger and a current sensor control battery state of charge of the silver-cadmium battery pack. Premature termination of the battery charge is prevented by a power available gate that also initiates charge current to the battery upon availability of excess power.

  5. DIMETHYL ETHER (DME)-FUELED SHUTTLE BUS DEMONSTRATION PROJECT

    SciTech Connect

    Elana M. Chapman; Shirish Bhide; Jennifer Stefanik; Howard Glunt; Andre L. Boehman; Allen Homan; David Klinikowski

    2003-04-01

    The objectives of this research and demonstration program are to convert a campus shuttle bus to operation on dimethyl ether, a potential ultra-clean alternative diesel fuel. To accomplish this objective, this project includes laboratory evaluation of a fuel conversion strategy, as well as, field demonstration of the DME-fueled shuttle bus. Since DME is a fuel with no lubricity (i.e., it does not possess the lubricating quality of diesel fuel), conventional fuel delivery and fuel injection systems are not compatible with dimethylether. Therefore, to operate a diesel engine on DME one must develop a fuel-tolerant injection system, or find a way to provide the necessary lubricity to the DME. In this project, they have chosen the latter strategy in order to achieve the objective with minimal need to modify the engine. The strategy is to blend DME with diesel fuel, to obtain the necessary lubricity to protect the fuel injection system and to achieve low emissions. The bulk of the efforts over the past year were focused on the conversion of the campus shuttle bus. This process, started in August 2001, took until April 2002 to complete. The process culminated in an event to celebrate the launching of the shuttle bus on DME-diesel operation on April 19, 2002. The design of the system on the shuttle bus was patterned after the system developed in the engine laboratory, but also was subjected to a rigorous failure modes effects analysis with help from Dr. James Hansel of Air Products. The result of this FMEA was the addition of layers of redundancy and over-pressure protection to the system on the shuttle bus. The system became operation in February 2002. Preliminary emissions tests and basic operation of the shuttle bus took place at the Pennsylvania Transportation institute's test track facility near the University Park airport. After modification and optimization of the system on the bus, operation on the campus shuttle route began in early June 2002. However, the work and challenges have continued as it has been difficult to maintain operability of the shuttle bus due to fuel and component difficulties. As of late June 2002, it appears that the pump head itself developed operational problems (loss of smooth function) leading to excessive stress on the magnetic coupling and excessive current draw to operate. A new pump head is being installed on the system to alleviate this problem and get the shuttle bus back in operation. In summary, the conversion is completed but there have been operational challenges in the field. They continue to work to make the shuttle bus as reliable to operate on DME-diesel blends as possible.

  6. Final Report for the H2Fuel Bus

    SciTech Connect

    Jacobs, W.D.

    1998-11-25

    The H2Fuel Bus is the world's first hydrogen-fueled electric hybrid transit bus. It was a project developed through a public/private partnership involving several leading technological and industrial organizations, with primary funding by the Department of Energy (DOE). The primary goals of the project are to gain valuable information on the technical readiness and economic viability of hydrogen fueled buses and to enhance the public awareness and acceptance of emerging hydrogen technologies.

  7. Compressed natural gas bus safety: a quantitative risk assessment.

    PubMed

    Chamberlain, Samuel; Modarres, Mohammad

    2005-04-01

    This study assesses the fire safety risks associated with compressed natural gas (CNG) vehicle systems, comprising primarily a typical school bus and supporting fuel infrastructure. The study determines the sensitivity of the results to variations in component failure rates and consequences of fire events. The components and subsystems that contribute most to fire safety risk are determined. Finally, the results are compared to fire risks of the present generation of diesel-fueled school buses. Direct computation of the safety risks associated with diesel-powered vehicles is possible because these are mature technologies for which historical performance data are available. Because of limited experience, fatal accident data for CNG bus fleets are minimal. Therefore, this study uses the probabilistic risk assessment (PRA) approach to model and predict fire safety risk of CNG buses. Generic failure data, engineering judgments, and assumptions are used in this study. This study predicts the mean fire fatality risk for typical CNG buses as approximately 0.23 fatalities per 100-million miles for all people involved, including bus passengers. The study estimates mean values of 0.16 fatalities per 100-million miles for bus passengers only. Based on historical data, diesel school bus mean fire fatality risk is 0.091 and 0.0007 per 100-million miles for all people and bus passengers, respectively. One can therefore conclude that CNG buses are more prone to fire fatality risk by 2.5 times that of diesel buses, with the bus passengers being more at risk by over two orders of magnitude. The study estimates a mean fire risk frequency of 2.2 x 10(-5) fatalities/bus per year. The 5% and 95% uncertainty bounds are 9.1 x 10(-6) and 4.0 x 10(-5), respectively. The risk result was found to be affected most by failure rates of pressure relief valves, CNG cylinders, and fuel piping. PMID:15876211

  8. Digital bus technology in new coal-fired plants

    SciTech Connect

    Blaney, J.; Murray, J.

    2007-10-15

    The main issues associated with including digital bus technology such as Foundation fieldbus, Profibus-DP or DeviceNet, in a coal-fired power plant are deciding which systems to install and determining how to implement it. Although still new, digital bus experiences to date have shown that the technology performs solidly and when wiring best practices are followed a significantly shorted commissioning cycle can be achieved. 1 fig., 2 tabs.

  9. Bus length and loading limits of MIL-STD-1553 buses

    NASA Astrophysics Data System (ADS)

    Briscoe, W. G.; Davila, Manuel; Skinner, Brian

    Tests performed on bus configurations having bus lengths up to 300 ft and up to 32 bus terminals are described. The tests involved the use of 8-stub couplers on the bus as well as the usual single stub couplers. Waveform photographs are provided for the various bus configurations and practical cable length and loading limits of MIL-STD-1553B buses are formulated.

  10. DIMETHYL ETHER (DME)-FUELED SHUTTLE BUS DEMONSTRATION PROJECT

    SciTech Connect

    Elana M. Chapman; Shirish Bhide; Jennifer Stefanik; Howard Glunt; Andre L. Boehman; Allen Homan; David Klinikowski

    2003-04-01

    The objectives of this research and demonstration program are to convert a campus shuttle bus to operation on dimethyl ether, a potential ultra-clean alternative diesel fuel. To accomplish this objective, this project includes laboratory evaluation of a fuel conversion strategy, as well as, field demonstration of the DME-fueled shuttle bus. Since DME is a fuel with no lubricity (i.e., it does not possess the lubricating quality of diesel fuel), conventional fuel delivery and fuel injection systems are not compatible with dimethyl ether. Therefore, to operate a diesel engine on DME one must develop a fuel-tolerant injection system, or find a way to provide the necessary lubricity to the DME. In this project, they have chosen the latter strategy in order to achieve the objective with minimal need to modify the engine. Their strategy is to blend DME with diesel fuel, to obtain the necessary lubricity to protect the fuel injection system and to achieve low emissions. The bulk of the efforts over the past year were focused on the conversion of the campus shuttle bus. This process, started in August 2001, took until April 2002 to complete. The process culminated in an event to celebrate the launching of the shuttle bus on DME-diesel operation on April 19, 2002. The design of the system on the shuttle bus was patterned after the system developed in the engine laboratory, but also was subjected to a rigorous failure modes effects analysis (FMEA, referred to by Air Products as a ''HAZOP'' analysis) with help from Dr. James Hansel of Air Products. The result of this FMEA was the addition of layers of redundancy and over-pressure protection to the system on the shuttle bus. The system became operational in February 2002. Preliminary emissions tests and basic operation of the shuttle bus took place at the Pennsylvania Transportation Institute's test track facility near the University Park airport. After modification and optimization of the system on the bus, operation on the campus shuttle route began in early June 2002. However, the work and challenges continued as it has been difficult to maintain operability of the shuttle bus due to fuel and component difficulties. In late June 2002, the pump head itself developed operational problems (loss of smooth function) leading to excessive stress on the magnetic coupling and excessive current draw to operate. A new pump head was installed on the system to alleviate this problem and the shuttle bus operated successfully on DME blends from 10-25 vol% on the shuttle bus loop until September 30, 2002. During the period of operation on the campus loop, the bus was pulled from service, operated at the PTI test track and real-time emissions measurements were obtained using an on-board emissions analyzer from Clean Air Technologies International, Inc. Particulate emissions reductions of 60% and 80% were observed at DME blend ratios of 12 vol.% and 25 vol.%, respectively, as the bus was operated over the Orange County driving cycle. Increases in NOx, CO and HC emissions were observed, however. In summary, the conversion of the shuttle bus was successfully accomplished, particulate emissions reductions were observed, but there were operational challenges in the field. Nonetheless, they were able to demonstrate reliable operation of the shuttle bus on DME-diesel blends.

  11. Dual Diagnosis

    MedlinePlus

    ... that make them feel better temporarily. Sometimes the substance abuse occurs first. Over time, that can lead to emotional and mental problems. Someone with a dual diagnosis must treat both conditions. For the treatment to be effective, the person needs to stop ...

  12. Quality-of-Service Analysis of Priority Queueing Systems under Long-Range Dependent and Short-Range Dependent Traffic

    NASA Astrophysics Data System (ADS)

    Jin, Xiaolong; Min, Geyong

    Priority queueing is an important and popular traffic scheduling mechanism for the provisioning of network Quality-of-Service (QoS) which has received numerous research efforts. Realistic traffic in multi-service networks exhibits heterogeneous Long-Range Dependent (LRD) and Short-Range Dependent (SRD) properties. This chapter presents an efficient and comprehensive performance model for investigating the QoS of priority queueing systems in the presence of heterogeneous LRD and SRD traffic. We derive and validate the closedform expressions of the queue length and loss probability distributions for individual traffic flows. The analytical model is used to evaluate the impact of LRD traffic on system performance under different working conditions and investigate the buffer management and allocation in priority queueing systems with QoS constraints.

  13. Effect of bus size and operation to crash occurrences.

    PubMed

    Chimba, Deo; Sando, Thobias; Kwigizile, Valerian

    2010-11-01

    This paper evaluates roadway and operational factors considered to influence crashes involving buses. Factors evaluated included those related to bus sizes and operation services. Negative binomial (NB) and multinomial logit (MNL) models were used in linearizing and quantifying these factors with respect to crash frequency and injury severities, respectively. The results showed that position of the bus travel lane, presence or absence of on-street shoulder parking, posted speed limit, lane width, median width, number of lanes per direction and number of vehicles per lane has a higher influence on bus crashes compared to other roadway and traffic factors. Wider lanes and medians were found to reduce probability of bus crashes while more lanes and higher volume per lane were found to increase the likelihood of occurrences of bus-related crashes. Roadways with higher posted speed limits excluding freeways were found to have high probability of crashes compared to low speed limit roadways. Buses traveling on the inner lanes and making left turns were found to have higher probability of crashes compared to those traveling on the right most lanes. The same factors were found to influence injury severity though with varying magnitudes compared to crash frequency. PMID:20728663

  14. 1393 Ring Bus at JPL: Description and Status

    NASA Technical Reports Server (NTRS)

    Wysocky, Terry R.

    2007-01-01

    Completed Ring Bus IC V&V Phase - Ring Bus Test Plan Completed for SIM Project - Applicable to Other Projects Implemented a Avionics Bus Based upon the IEEE 1393 Standard - Excellent Starting Point for a General Purpose High-Speed Spacecraft Bus - Designed to Meet SIM Requirements for - Real-time deterministic, distributed systems. - Control system requirements - Fault detection and recovery Other JPL Projects Considering Implementation F'light Software Ring Bus Driver Module Began in 2006, Continues Participating in Standard Revision. Search for Earth-like planets orbiting nearby stars and measure the masses and orbits of the planets it finds. Survey 2000 nearby stars for planetary systems to learn whether our Solar System is unusual, or typical. Make a new catalog of star position 100 times more accurate than current measurements. Learn how our galaxy formed and will evolve by studying the dynamics of its stars. Critically test models of exactly how stars shine, including exotic objects like black holes, neutron stars and white dwarfs.

  15. Approximate-solution techniques for queueing network models of concurrent processing and other nonproduct form problems

    SciTech Connect

    Almeida, V.A.F.

    1987-01-01

    Concurrency is a central issue in current and future computer systems. In the last few years, several computers with advanced architectures have been announced. All of them employ some form of concurrency to achieve higher performance. This dissertation provides an improved trade-off between accuracy and simplicity in modeling programs with internal concurrency. Several different synchronization mechanisms are analyzed. A reduction technique is developed that analyzes the performance of parallel-processing systems and that preserves the simplicity of standard queueing network-theory techniques (e.g., the mean value analysis algorithm). The technique provides quite accurate approximations on the performance of such systems. Extensions related to the applicability of the reduction technique are also presented. The technique successfully applies to other classical non product form problems (e.g., simultaneous resource possession and routing to the shortest queue). The significance of this research stems from the need for models that yield insights into the behavior of parallel-processing systems.

  16. Design, implementation, and operation of a class based batch queue scheduler for VAX/VMS

    SciTech Connect

    Chadwick, K.

    1988-05-20

    Fermilab found that the standard VMS batch configuration options were inadequate for the job mix that exists on the Fermilab central computer facility VAX cluster. Accordingly, Fermilab designed and implemented a class based batch queue scheduler. This scheduler makes use of the standard VMS job controller and batch system. Users interact with the scheduler at job submission time by specification of CPU time limits and batch job characteristics. This scheduler allows Fermilab to make efficient use of our large heterogeneous VAX cluster which contains machines ranging from a VAX 780 to a VAX 8800. The scheduler was implemented using the VMS system services $GETQUI and $SNDJBC, without changes to the existing VMS job scheduler. As a result, the scheduler should remain compatible with future VMS versions. This session will discuss the design goals, implementation, and operational experience with Fermilab's class based batch queue scheduler.

  17. Multicast Services of QoS-Aware Active Queue Management over IP Multimedia Applications

    NASA Astrophysics Data System (ADS)

    Hwang, I.-Shyan; Hwang, Bor-Jiunn; Chang, Pen-Ming

    2010-10-01

    Recently, the multimedia services such as IPTV, video conference emerges to be the main traffic source. When UDP coexists with TCP, it induces not only congestion collapse but also unfairness problem. In this paper, a new Active Queue Management (AQM) algorithm, called Traffic Sensitive Active Queue Management (TSAQM), is proposed for providing multimedia services. The TSAQM comprise Dynamic Weight Allocate Scheme (DWAS) and Service Guarantee Scheme (SGS), the purpose of DWAS is to allocate resource with fairness and high end-user utility, and the purpose of SGS is to determine the satisfactory threshold (TH) and threshold region (TR). Several objectives of this proposed scheme include achieving high end-user utility for video service, considering the multicast as well as unicast proprieties to meet inter-class fairness and achieving the QoS requirement by adjusting the thresholds adaptively based on traffic situations.

  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. An Active Queue Management for QoS Guarantee of the High Priority Service Class

    NASA Astrophysics Data System (ADS)

    Kim, Hyun Jong; Shim, Jae Chan; Kim, Hwa-Suk; Cho, Kee Seong; Choi, Seong Gon

    In this paper, we propose the active queue management mechanism (Active-WRED) for guaranteeing the quality of the high priority service class (VoIP or IPTV) in the multi-class traffic service environment. In the congestion situation, this mechanism increases the drop probability of the low priority traffic and reduces the drop probability of the high priority traffic; therefore it can guarantee the quality of the high priority service class from the poor quality by the packet loss.

  20. An example of a constructive specification of a queue, preliminary report, appendix B

    NASA Technical Reports Server (NTRS)

    Benzinger, Leonora

    1985-01-01

    An example is presented of the constructive specification of a queue which is done in the style of (Jones 80) using the Vienna Development Method. The basic approach is that of data type refinement. The techniques used are not restricted to those used by Jones, particularly with respect to the method for proving properties of the retrieve function for linked lists, however the notation is consistent with his.

  1. American Fuel Cell Bus Project Evaluation. Second Report

    SciTech Connect

    Eudy, Leslie; Post, Matthew

    2015-09-01

    This report presents results of the American Fuel Cell Bus (AFCB) Project, a demonstration of fuel cell electric buses operating in the Coachella Valley area of California. The prototype AFCB was developed as part of the Federal Transit Administration's (FTA's) National Fuel Cell Bus Program. Through the non-profit consortia CALSTART, a team led by SunLine Transit Agency and BAE Systems developed a new fuel cell electric bus for demonstration. SunLine added two more AFCBs to its fleet in 2014 and another in 2015. FTA and the AFCB project team are collaborating with the U.S. Department of Energy (DOE) and DOE's National Renewable Energy Laboratory to evaluate the buses in revenue service. This report summarizes the performance results for the buses through June 2015.

  2. 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. PMID:18995853

  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. The use of queueing and simulative analyses to improve an overwhelmed pharmacy call center.

    PubMed

    Day, T Eugene; Li, W Max; Ingolfsson, Armann; Ravi, Nathan

    2010-10-01

    Like many others, the St. Louis Veterans Administration Medical Center (VAMC) Pharmacy help desk receives far more calls than can be processed by current staffing levels. The objective of the study is to improve pharmaceutical services provided by the call center, by using queueing theory and discrete event dynamic simulation to analyze incoming telephone traffic to the help desk. Queueing and simulation models using both archival and hand-gathered data over a 1-year period were created, compared, and presented in order to determine the minimum quantities of staff needed to reach the desired service threshold. The simulation model was validated in comparison with real-world data. Results suggest that telephone traffic congestion in this setting may be alleviated by increasing the number of staff responsible for telephone services from 2 to 6 throughout the week, with an additional one serving on Monday. Both queueing and simulative models can be used to improve overwhelm pharmacy call centers, by determining the theoretical minimal staff needed to reach a service threshold. PMID:21507852

  5. Effects of Bursty and Correlated Traffic on the Performance of Active Queue Management Schemes

    NASA Astrophysics Data System (ADS)

    Wang, Lan; Min, Geyong; Awan, Irfan

    Motivated by the need of performance analysis of Active Queue Management (AQM) schemes under highly bursty and correlated traffic in multi-service networks, this paper develops an analytical model for a finite capacity queueing system with an AQM scheme subject to two heterogeneous classes of traffic which are modeled, respectively, by the bursty Markov-Modulated Poisson Process (MMPP) and non-bursty Poisson Process. The well-known MMPP is adopted for modelling bursty traffic owing to its ability to model the time-varying arrival rate and capture the important correlation between inter-arrival times while still maintaining analytical tractability. We derive the aggregate and marginal performance metrics including the mean queue length, response time, system utilization, throughput and loss probability. The accuracy of the model is validated by comparing analytical results with those obtained from simulation. We further focus on the evaluation of the effects of traffic burstiness and correlation of inter-arrival time on the aggregate performance metrics of AQM with different thresholds.

  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. PMID:18826003

  7. Fuzzy logic control for active bus suspension system

    NASA Astrophysics Data System (ADS)

    Turkkan, Mujde; Yagiz, Nurkan

    2013-02-01

    In this study an active controller is presented for vibration suppression of a full-bus suspension model that use air spring. Since the air spring on the full-bus model may face different working conditions, auxiliary chambers have been designed. The vibrations, caused by the irregularities of the road surfaces, are tried to be suppressed via a multi input-single output fuzzy logic controller. The effect of changes in the number of auxiliary chambers on the vehicle vibrations is also investigated. The numerical results demonstrate that the presented fuzzy logic controller improves both ride comfort and road holding.

  8. S-100-bus microcomputers aim at high-performance systems

    SciTech Connect

    Warren, C.

    1982-08-18

    The explosion in integrated low-cost desktop computer systems for single-user dedicated applications has a companion trend: a growing interest in high-performance multitasking multiuser systems and in system architecture which lend themselves easily to peripheral- and procesing-power expansion. The mature S-100 (IEEE-696) bus, once the domain of hobby computers, offers a variety of advantages to serve such applications; thus, systems designed around this bus are enjoying a revival. Microcomputers, from a number of manufacturers, which follow this trend are described.

  9. Performance Evaluation of UHF RFID Technologies for Real-Time Bus Recognition in the Taipei Bus Station

    PubMed Central

    Own, Chung-Ming; Lee, Da-Sheng; Wang, Ti-Ho; Wang, De-Jun; Ting, Yu-Lun

    2013-01-01

    Transport stations such as airports, ports, and railways have adopted blocked-type pathway management to process and control travel systems in a one-directional manner. However, this excludes highway transportation where large buses have great variability and mobility; thus, an instant influx of numerous buses increases risks and complicates station management. Focusing on Taipei Bus Station, this study employed RFID technology to develop a system platform integrated with modern information technology that has numerous characteristics. This modern information technology comprised the following systems: ultra-high frequency (UHF) radio-frequency identification (RFID), ultrasound and license number identification, and backstage graphic controls. In conclusion, the system enabled management, bus companies, and passengers to experience the national bus station's new generation technology, which provides diverse information and synchronization functions. Furthermore, this technology reached a new milestone in the energy-saving and efficiency-increasing performance of Taiwan's buses. PMID:23778192

  10. Single chip Bus Interface Unit eases MIL-STD-1553B remote terminal/bus controller designs

    NASA Astrophysics Data System (ADS)

    Schaire, S.; Cavin, J.

    A new single-chip 'Smart' Bus Interface Unit (BIU), which is basically a communications processor on a chip, has been developed for use as a remote terminal and a bus controller with MIL-STD-1553B. The BIU design approach allows for future multiplex terminals without the software or BIU becoming obsolete. The use of BIU without a processor and with 8-bit, 16-bit, and other microprocessors is discussed. A sample application with the M68000 microprocessor and the inherent flexibility of the proposed design for future applications are demonstrated.

  11. School Bus Safety: What Can Our Schools Do to Protect Our Children?

    ERIC Educational Resources Information Center

    Dargan, Thomas J.; Silverstone, Adam H.

    2014-01-01

    School districts and school bus contractors are entrusted with the most important of all road users--our nation's children. In the wake of recent newsworthy accidents and attention grabbing headlines regarding unfit bus drivers, claims premised upon school bus accidents have become increasingly tangential and, in turn, personal injury attorneys…

  12. SunLine Leads the Way in Demonstrating Hydrogen-Fueled Bus Technologies (Brochure)

    SciTech Connect

    Not Available

    2011-01-01

    This brochure describes SunLine Transit Agency's newest advanced technology fuel cell electric bus. SunLine is collaborating with the U.S. Department of Energy's Fuel Cell Technologies Program to evaluate the bus in revenue service. This bus represents the sixth generation of hydrogen-fueled buses that the agency has operated since 2000.

  13. Instructor's Behind-the-Wheel Guide for California's Bus Driver's Training Course.

    ERIC Educational Resources Information Center

    California State Dept. of Education, Sacramento.

    Intended to help produce safe, competent California school bus drivers, this document contains instructor's materials for a bus driver education course with eight sequential skill levels, including a final appraisal. The first section contains the curriculum's purpose and objectives, the California standards for a state-certified bus driver…

  14. 49 CFR Appendix A to Part 665 - Tests To Be Performed at the Bus Testing Facility

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... assessed. (6) With the bus at curb weight possible damages or deformation associated with lifting the bus... the bus with a distributed load equal to 2.5 times the load applied for the gross weight portions of... gross vehicle weight, with one wheel on top of a curb and then in a pothole. This test should...

  15. Behavior Modification of Aggressive Behavior on a Nursery School Bus: A Case Study.1

    ERIC Educational Resources Information Center

    Whitehurst, Carol; Miller, Edward

    1973-01-01

    A case study is presented in which aggressive behavior of two pre-school boys on a nursery school bus was modified by the introduction of a negative punishment contingency in which the Ss were told they would be detained on the bus until the second time the bus passed their house (delay of reinforcement) if abusive behavior occurred. (Author)

  16. Fiber optic data bus using Frequency Division Multiplexing (FDM) and an asymmetric coupler

    NASA Technical Reports Server (NTRS)

    Zanger, M.; Webster, L.

    1984-01-01

    A fiber optic data bus, using frequency division multiplexing (FDM) is discussed. The use of FDM is motivated by the need to avoid central control of the bus operation. A major difficulty of such a data bus is introduced by the couplers. An efficient low loss access coupler with an asymmetric structure is presented, and manufacturing processes for the coupler are proposed.

  17. 49 CFR 571.220 - Standard No. 220; School bus rollover protection.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 6 2010-10-01 2010-10-01 false Standard No. 220; School bus rollover protection... STANDARDS Federal Motor Vehicle Safety Standards § 571.220 Standard No. 220; School bus rollover protection. S1. Scope. This standard establishes performance requirements for school bus rollover protection....

  18. School Bus Rider Safety Education Modules for Use with Drills on School Buses.

    ERIC Educational Resources Information Center

    New York State Education Dept., Albany. Div. of Physical Education, Fitness, Health, Nutrition and Safety Services.

    Developed for teachers and members of the pupil transportation staff who conduct school bus drills, these 10 lesson outlines are intended for classroom instruction on school bus safety. Lessons may be adapted to fit the grade level, intelligence, and special needs of students. Topics covered are: preparing to ride the bus, boarding and proceeding…

  19. Computer-Based Video Instruction to Teach Students with Intellectual Disabilities to Use Public Bus Transportation

    ERIC Educational Resources Information Center

    Mechling, Linda; O'Brien, Eileen

    2010-01-01

    This study investigated the effectiveness of computer-based video instruction (CBVI) to teach three young adults with moderate intellectual disabilities to push a "request to stop bus signal" and exit a city bus in response to target landmarks. A multiple probe design across three students and one bus route was used to evaluate effectiveness of…

  20. Bus Operations for Pupil Transportation. "Chrome-Yellow and Red Lights."

    ERIC Educational Resources Information Center

    Rannels, Morris W.

    This paper is based on a committee report of the last National School Bus Conference on "Minimum Standards for School Buses." Standards for school bus operations are included for (1) administrators, (2) supervisors, (3) school bus drivers, (4) student passengers, and (5) maintenance and service personnel. The report deals also with procedures for…

  1. Beware of high stresses in ``A`` frame supported two-level bus structures

    SciTech Connect

    Thaik, A.

    1995-10-01

    Rigid-bus structures in many low profile, high voltage transmission substations consist of two-level bus assemblies of tubular conductors with one bus assembly supporting the other bus assembly with rigid tubular ``A`` frames at the crossover points. The lower-level bus is normally supported by a single porcelain post insulator under the ``A`` frame. Rigid ``A`` frames not only support the upper-level bus assembly, but also make the electrical connections between the two buses. This paper addresses the stress problem in the lower-level bus of the two-level bus structure. It presents the results of the structural analysis of a sample two-level bus structure using a simple structural method based on the Three Moment Theorem and equilibrium equations. A spreadsheet template is used to perform the mathematical calculations. The spreadsheet first calculates the maximum allowable bus span length in accordance with the IEEE Standard 605 and then determines the internal stress on the upper and lower-level bus conductors in the two-level rigid bus structures.

  2. High-Tech School Bus Teaches Students on the Road

    ERIC Educational Resources Information Center

    Katims, Lauren

    2011-01-01

    Last year, kindergarten through high school students in the rural Hector, Arkansas, School District barely had the technology resources that keep kids interested in math and science. This year, they potentially have the most advanced resources in the country--before they even step into the classroom. One school bus in Arkansas' Pope County has

  3. Training Needs Analysis for Bus Depot Managers at GSRTC

    ERIC Educational Resources Information Center

    Shah, Hardik; Gopal, Raj

    2012-01-01

    Purpose: With rapid industrialization and population growth in the urban and rural areas in India, the demand for public transport has risen sharply. In the fast changing scenario in the public transit sector, the role of a bus depot manager (DM) has also undergone substantial transformation. This paper aims to identify and gauge the…

  4. Augmented thermal bus wih multiple thermoelectric devices individually controlled

    NASA Technical Reports Server (NTRS)

    Schrage, Dean S. (Inventor)

    1994-01-01

    The present invention is directed to an augmented thermal bus. In the present design a plurality of thermo-electric heat pumps are used to couple a source plate to a sink plate. Each heat pump is individually controlled by a model based controller. The controller coordinates the heat pumps to maintain isothermality in the source.

  5. Bus Talk: A Preliminary Analysis of Children's Decontextualized Talk

    ERIC Educational Resources Information Center

    Marvin, Christine A.; Cline, Keely D.

    2010-01-01

    Decontextualized conversational talk has been recognized as an important foundation for young children's early literacy and academic success. In this study, the authors explore the tape-recorded conversations of 15 typically developing preschool-age children. The children's talk was recorded as they traveled home from preschool on a school bus

  6. What's Happening on the School Bus Performance Front?

    ERIC Educational Resources Information Center

    Combs, Hanford L.

    The most urgent order of business in the national scene is to complete the development of a series of new performance tests for school bus bodies and chassis to establish a benchmark for safe construction that can be verified by independent testing agencies. Such performance tests should incorporate the new Federal Joint Strength Efficiency…

  7. How to Cut Costs by Saving School Bus Fuel.

    ERIC Educational Resources Information Center

    Seiff, Hank

    A program started in Washington County, Maryland in 1980 has been successful in saving school bus fuel and bringing down transportation costs incurred by its fleet of 200 buses. Driver training and motivation, as well as a partial transfer to diesel buses, are at the heart of the program. The drivers are taught five fuel saving techniques: cut

  8. School Bus Safety Advisory Committee: 1999 Annual Report.

    ERIC Educational Resources Information Center

    Lazenberry, Dennis; Anderson, Barbara

    This report summarizes the deliberations and recommendations of Minnesota's School Bus Safety Advisory Committee (SBSAC). The committee, which operates under the auspices of the Minnesota Department of Public Safety, is charged to study issues affecting the safety of students on school buses, arrive at consensus on ways to improve student safety…

  9. Implementation of a Walking School Bus: Lessons Learned

    ERIC Educational Resources Information Center

    Kong, Alberta S.; Sussman, Andrew L.; Negrete, Sylvia; Patterson, Nissa; Mittleman, Rachel; Hough, Richard

    2009-01-01

    Background: Obesity is rapidly becoming the most common chronic medical condition affecting children. To address this crisis, an Albuquerque, New Mexico, elementary school partnered with University of New Mexico researchers and conducted a Walking School Bus (WSB). The purpose of this article is to examine the feasibility of implementing a WSB.

  10. School Bus Driver Instructional Program. Trainee Study Guide -- Advanced Unit.

    ERIC Educational Resources Information Center

    Department of Transportation, Washington, DC. National Highway Safety Bureau.

    A standardized and comprehensive school bus driver instructional program has been developed under contract with the Federal Government. The course has been organized to provide in one package a program for developing the minimum skills and knowledge which the proficient driver might require. This guide contains the materials presented in eight

  11. 26. DETAIL TO NORTH OF BUS STRUCTURE. NEW POWERHOUSE SECOND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. DETAIL TO NORTH OF BUS STRUCTURE. NEW POWERHOUSE SECOND FLOOR, WITH OIL CIRCUIT BREAKER UNITS (LEFT) AND TANK LIFTER (CENTER) - Trenton Falls Hydroelectric Station, Powerhouse & Substation, On west bank of West Canada Creek, along Trenton Falls Road, 1.25 miles north of New York Route 28, Trenton Falls, Oneida County, NY

  12. Training Needs Analysis for Bus Depot Managers at GSRTC

    ERIC Educational Resources Information Center

    Shah, Hardik; Gopal, Raj

    2012-01-01

    Purpose: With rapid industrialization and population growth in the urban and rural areas in India, the demand for public transport has risen sharply. In the fast changing scenario in the public transit sector, the role of a bus depot manager (DM) has also undergone substantial transformation. This paper aims to identify and gauge the

  13. How to Cut Costs by Saving School Bus Fuel.

    ERIC Educational Resources Information Center

    Seiff, Hank

    A program started in Washington County, Maryland in 1980 has been successful in saving school bus fuel and bringing down transportation costs incurred by its fleet of 200 buses. Driver training and motivation, as well as a partial transfer to diesel buses, are at the heart of the program. The drivers are taught five fuel saving techniques: cut…

  14. Improving School Bus Safety. Transportation Research Board Special Report 222.

    ERIC Educational Resources Information Center

    National Academy of Sciences - National Research Council, Washington, DC. Transportation Research Board.

    While school buses transport more passengers per trip, the rate of occupant fatalities per mile driven for school buses is one-quarter that for passenger cars. Nevertheless, the public expects school districts and other school bus operators to take all reasonable precautions to protect children as they travel to and from school. Although a variety…

  15. 38. Photocopy of photograph (Pentran file), photographer unknown. Bus garage ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    38. Photocopy of photograph (Pentran file), photographer unknown. Bus garage to left now demolished. Trolley car drivers, maintenance personnel and management staff in 1915. VIEW SOUTH - Newport News & Old Point Railway & Electric Company, Trolley Barn & Administration Building, 3400 Victoria Boulevard, Hampton, Hampton, VA

  16. Research Says "No" to School Bus Seat Belts.

    ERIC Educational Resources Information Center

    Wineland, Charles L.

    1986-01-01

    Presents factual data on research in school bus safety that shows that seat belts in school buses may actually be detrimental to students. Includes data from surveys and research tests and sources for additional information on seat belts in school buses. (MD)

  17. School Bus Safety. An AS&U Roundtable.

    ERIC Educational Resources Information Center

    American School and University, 1985

    1985-01-01

    A roundtable discussion of the issue of seat belts in school buses features United States Representative Peter H. Kostmayer, who has introduced a bill providing incentive grants to states to adopt and enforce laws requiring the use of seat belts in new school buses; three bus manufacturing executives; and two educators. (MLF)

  18. Issues in School Bus Safety: Real or Red Herring?

    ERIC Educational Resources Information Center

    Leeds, Robin L.

    1999-01-01

    In many states, the greatest threat to safe student transportation is elimination of the school transportation program. Using public transit buses, large vans, smaller vehicles, or specialized equipment can cause major-issue headaches. False issues include controversies over seat belts, bus design, and optional "bells and whistles." (10…

  19. Interface For MIL-STD-1553B Data Bus

    NASA Technical Reports Server (NTRS)

    Davies, Bryan L.; Osborn, Stephen H.; Sullender, Craig C.

    1993-01-01

    Electronic control-logic subsystem acts as interface between microcontroller and MIL-STD-1553B data bus. Subsystem made of relatively small number of integrated circuits. Advantages include low power, few integrated-circuit chips, and little need for control signals.

  20. Course Guide for School Bus Driver Training in Texas. Revised.

    ERIC Educational Resources Information Center

    Texas State Dept. of Public Safety, Austin.

    The safe and effective transportation of pupils to and from schol is an integral part of a sound educational program. This course guide is a study and reference tool for use in a training course designed to promote the competency of school bus drivers throughout the State of Texas. Unit 1 of the guide provides an overview of the transportation…

  1. High-Tech School Bus Teaches Students on the Road

    ERIC Educational Resources Information Center

    Katims, Lauren

    2011-01-01

    Last year, kindergarten through high school students in the rural Hector, Arkansas, School District barely had the technology resources that keep kids interested in math and science. This year, they potentially have the most advanced resources in the country--before they even step into the classroom. One school bus in Arkansas' Pope County has…

  2. Implementation of a Walking School Bus: Lessons Learned

    ERIC Educational Resources Information Center

    Kong, Alberta S.; Sussman, Andrew L.; Negrete, Sylvia; Patterson, Nissa; Mittleman, Rachel; Hough, Richard

    2009-01-01

    Background: Obesity is rapidly becoming the most common chronic medical condition affecting children. To address this crisis, an Albuquerque, New Mexico, elementary school partnered with University of New Mexico researchers and conducted a Walking School Bus (WSB). The purpose of this article is to examine the feasibility of implementing a WSB.…

  3. Manual of First Aid Practices for School Bus Drivers.

    ERIC Educational Resources Information Center

    Nesbitt, William R.

    This manual is intended to assist local school authorities in California in providing the required course in instruction in first aid practices for school bus drivers. While it deals with basic principles of handling serious medical emergencies, major emphasis is on minor injuries or illnesses that are most likely to occur while students are…

  4. School Bus Driver Instructor Training Institute. Final Report.

    ERIC Educational Resources Information Center

    Cleven, Arlene M.; Fucigna, Joseph T.

    The National Highway Traffic Safety Association (NHTSA) has supported the development of a training program for school bus drivers in the form of a curriculum package (instructor's, course, and trainee study guides). To assist the States in making the program operational, NHTSA in 1974 supported the conduct of five five-day institutes to explain…

  5. School Bus Crash Rates on Routine and Nonroutine Routes

    ERIC Educational Resources Information Center

    O'Neal, Elizabeth; Ramirez, Marizen; Hamann, Cara; Young, Tracy; Stahlhut, Mary; Peek-Asa, Corinne

    2014-01-01

    Background: Although prior research has established that school buses are a safe form of transportation, crashes can produce catastrophic consequences. School buses have 2 types of routes: predictable, routine routes that take children to and from school and less predictable, nonroutine routes for school events. No studies have examined school bus

  6. Characterisation of an urban bus network for environmental purposes.

    PubMed

    André, Michel; Villanova, André

    2004-12-01

    Since pollutant emissions are closely related to the operating conditions of vehicles, their evaluation usually involves studying these operating conditions (through bus instrumentation and monitoring under actual operation), the design of representative driving or engine test cycles and the measurement of pollutant emissions. A preliminary characterisation of the routes on a bus network should make it possible to identify typical routes, the driving conditions and pollutant emissions of which are then studied. Two approaches are envisaged and applied to the Paris area, for which a wealth of information is available, which should be transferable to other bus networks. Both approaches are based on factorial analysis and automatic clustering, to allow optimum description and the identification of a pertinent typology of the bus routes in several classes. The first attempt at characterisation is based on statistics relating to bus operations: route characteristics (length, dedicated bus lanes, number of stops, location of stops: schools, tourist sites, hospitals, railways or underground stations), travel time, commercial speed, annual statistics (number of passengers, number of vehicles per hour, total kilometres), the irregularity of travel (variation of travel times, injuries, congestion.), as well as information on the problems encountered (congestion, distribution of the passenger load, junctions, bends). A second approach is based on the analysis of the "urban context" in which buses are driven. Population, employment, housing, road network, traffic and places that generate or disturb traffic (schools, railway stations, shopping areas, etc.) are calculated for the Ile de France region, by cells of 100 x 100 m, and collected in a geographical information system (GIS). Statistical analyses enable a typology of these urban cells to be established, the main parameters being density, type of housing, road types and traffic levels. The bus routes are then analysed according to their itineraries across these typical areas (distances travelled in each type of area) using a similar approach. A comparison of the typologies obtained from operational data and from urban data highlights the advantages and disadvantages of the two approaches. The first result from these typologies is the selection of routes which are representative of the different classes, in order to instrument buses and record driving patterns. This method should also make it possible to link driving conditions and urban characteristics, and then to allocate pollutant emission factors to given geographical situations, in particular, in the context of emission inventories or impact studies. PMID:15504495

  7. Public transit bus ramp slopes measured in situ.

    PubMed

    Bertocci, Gina; Frost, Karen; Smalley, Craig

    2014-05-01

    Abstract Purpose: The slopes of fixed-route bus ramps deployed for wheeled mobility device (WhMD) users during boarding and alighting were assessed. Measured slopes were compared to the proposed Americans with Disabilities Act (ADA) maximum allowable ramp slope. Methods: A ramp-embedded inclinometer measured ramp slope during WhMD user boarding and alighting on a fixed-route transit bus. The extent of bus kneeling was determined for each ramp deployment. In-vehicle video surveillance cameras captured ramp deployment level (street versus sidewalk) and WhMD type. Results: Ramp slopes ranged from -4° to 15.5° with means of 4.3° during boarding (n = 406) and 4.2° during alighting (n = 405). Ramp slope was significantly greater when deployed to street level. During boarding, the proposed ADA maximum allowable ramp slope (9.5°) was exceeded in 66.7% of instances when the ramp was deployed to street level, and in 1.9% of instances when the ramp was deployed to sidewalk level. During alighting, the proposed ADA maximum allowable slope was exceeded in 56.8% of instances when the ramp was deployed to street level and in 1.4% of instances when the ramp was deployed to sidewalk level. Conclusions: Deployment level, built environment and extent of bus kneeling can affect slope of ramps ascended/descended by WhMD users when accessing transit buses. Implications for Rehabilitation Since public transportation services are critical for integration of wheeled mobility device (WhMD) users into the community and society, it is important that they, as well as their therapists, are aware of conditions that may be encountered when accessing transit buses. Knowledge of real world ramp slope conditions that may be encountered when accessing transit buses will allow therapists to better access capabilities of WhMD users in a controlled clinical setting. Real world ramp slope conditions can be recreated in a clinical setting to allow WhMD users to develop and practice necessary skills to safely navigate this environment. Knowing that extent of bus kneeling and ramp deployment level can influence ramp slope, therapists can educate WhMD users to request bus operators further kneel the bus floor and/or redeploy the ramp to a sidewalk level when appropriate, so that the least practicable slope will be presented for ingress/egress. PMID:24785405

  8. Real life testing of a Hybrid PEM Fuel Cell Bus

    NASA Astrophysics Data System (ADS)

    Folkesson, Anders; Andersson, Christian; Alvfors, Per; Alaküla, Mats; Overgaard, Lars

    Fuel cells produce low quantities of local emissions, if any, and are therefore one of the most promising alternatives to internal combustion engines as the main power source in future vehicles. It is likely that urban buses will be among the first commercial applications for fuel cells in vehicles. This is due to the fact that urban buses are highly visible for the public, they contribute significantly to air pollution in urban areas, they have small limitations in weight and volume and fuelling is handled via a centralised infrastructure. Results and experiences from real life measurements of energy flows in a Scania Hybrid PEM Fuel Cell Concept Bus are presented in this paper. The tests consist of measurements during several standard duty cycles. The efficiency of the fuel cell system and of the complete vehicle are presented and discussed. The net efficiency of the fuel cell system was approximately 40% and the fuel consumption of the concept bus is between 42 and 48% lower compared to a standard Scania bus. Energy recovery by regenerative braking saves up 28% energy. Bus subsystems such as the pneumatic system for door opening, suspension and brakes, the hydraulic power steering, the 24 V grid, the water pump and the cooling fans consume approximately 7% of the energy in the fuel input or 17% of the net power output from the fuel cell system. The bus was built by a number of companies in a project partly financed by the European Commission's Joule programme. The comprehensive testing is partly financed by the Swedish programme "Den Gröna Bilen" (The Green Car). A 50 kW el fuel cell system is the power source and a high voltage battery pack works as an energy buffer and power booster. The fuel, compressed hydrogen, is stored in two high-pressure stainless steel vessels mounted on the roof of the bus. The bus has a series hybrid electric driveline with wheel hub motors with a maximum power of 100 kW. Hybrid Fuel Cell Buses have a big potential, but there are still many issues to consider prior to full-scale commercialisation of the technology. These are related to durability, lifetime, costs, vehicle and system optimisation and subsystem design. A very important factor is to implement an automotive design policy in the design and construction of all components, both in the propulsion system as well as in the subsystems.

  9. Development of a dual-field heteropoplar power converter

    NASA Technical Reports Server (NTRS)

    Eisenhaure, D. B.; Johnson, B.; Bliamptis, T.; St. George, E.

    1981-01-01

    The design and testing of a 400 watt, dual phase, dual rotor, field modulated inductor alternator is described. The system is designed for use as a flywheel to ac utility line or flywheel to dc bus (electric vehicle) power converter. The machine is unique in that it uses dual rotors and separately controlled fields to produce output current and voltage which are in phase with each other. Having the voltage and current in phase allows the power electronics to be made of simple low cost components. Based on analytical predictions and experimental results, development of a complete 22 kilowatt (30 Hp) power conversion system is recommended. This system would include power electronics and controls and would replace the inductor alternator with an improved electromagnetic conversion system.

  10. Bus water storage tank as a reservoir of Legionella pneumophila.

    PubMed

    Jur?ev-Savi?evi?, Anamarija; Bradari?, Nikola; Pai?, Vlado Ozic; Muli?, Rosanda; Puntari?, Dinko; Mie, Kornelija

    2014-09-01

    Health concerns associated with Legionnaires' disease have been identified as an area of the increasing public and professional interest. Any natural water or man-made water systems worldwide might be reservoirs of Legionellae. We presented a sporadic, community-acquired case of Legionnaires' disease caused by Legionellapneumophila serogroup 1 in a bus driver who used water for hand and face washing from a bus water storage tank. The history of any other usual place of exposure to Legionellae was negative. The water from the tank was dirty, filled with sediment and leaves, at the temperature of 22 degrees C. The water was heavily contaminated with Legionella pneumophila serogroup 1 isolated from each sample with the concentration of 66,000, 16,000, 42,000, 56,000 and 34,000 CFU/L. The disinfection of the bus water storage tank was made using hyperclorination with 50 mg/L of free residual chlorine. The control sampling one week after the disinfection yielded negative results. So far, there are no recommendations on regular management or disinfection of water in bus storage tanks, but it seems to be reasonable to assume that passengers as well as bus drivers may be exposed to Legionella and therefore at risk of acquiring the infection. These recommendations should include regular empting, rinsing and filling the tank with fresh tap water, at least once a week. Finally, we have to be aware that Legionella bacteria are ubiquitous and any potential mode of producing contaminated aerosol should not be overlooked during an epidemiological field investigation and proposed appropriate measures. PMID:25507374

  11. Bus water storage tank as a reservoir of Legionella pneumophila.

    PubMed

    Jur?ev-Savi?evi?, Anamarija; Bradari?, Nikola; Pai?, Vlado Ozic; Muli?, Rosanda; Puntari?, Dinko; Mie, Kornelija

    2014-09-01

    Health concerns associated with Legionnaires' disease have been identified as an area of the increasing public and professional interest. Any natural water or man-made water systems worldwide might be reservoirs of Legionellae. We presented a sporadic, community-acquired case of Legionnaires' disease caused by Legionellapneumophila serogroup 1 in a bus driver who used water for hand and face washing from a bus water storage tank. The history of any other usual place of exposure to Legionellae was negative. The water from the tank was dirty, filled with sediment and leaves, at the temperature of 22 degrees C. The water was heavily contaminated with Legionella pneumophila serogroup 1 isolated from each sample with the concentration of 66,000, 16,000, 42,000, 56,000 and 34,000 CFU/L. The disinfection of the bus water storage tank was made using hyperclorination with 50 mg/L of free residual chlorine. The control sampling one week after the disinfection yielded negative results. So far, there are no recommendations on regular management or disinfection of water in bus storage tanks, but it seems to be reasonable to assume that passengers as well as bus drivers may be exposed to Legionella and therefore at risk of acquiring the infection. These recommendations should include regular empting, rinsing and filling the tank with fresh tap water, at least once a week. Finally, we have to be aware that Legionella bacteria are ubiquitous and any potential mode of producing contaminated aerosol should not be overlooked during an epidemiological field investigation and proposed appropriate measures. PMID:25420390

  12. Optoelectronic packaging for 16-channel optical backplane bus with VHOEs

    NASA Astrophysics Data System (ADS)

    Choi, J. H.; Bi, H.; Ellis, J.; Chen, R. T.

    2007-02-01

    A novel 16-channel optical backplane bus with volume holographic optical elements (VHOEs), operating as diffraction grating beam alignment guides, was designed and fabricated for a high-performance computing system multi-slot bus. These thin film VHOEs were fabricated to diffract light beams for each bus slot into a glass wave-guiding plate (refractive index 1.52) for total internal reflection to other slot positions. Slot-to-slot optical alignment issues, including channel crosstalk and beam alignment tolerances, were computer modeled to optimize a low cost and simple optical packaging structure. For each slot position, a 4 × 8 element optical packaging plate was then fabricated to allow insertion of 16 VCSELs and 16 Photodiodes, each in an individual TO-46 can. Through the VHOE, the slot-to-slot fan-out received beam intensities were experimentally measured for each of the 16 channels and found to be in the range of 90 μW ~ 150 μW. This 90 μW minimum fan-out power is 5dB greater than the receiver sensitivity requirement. In this study, the maximum 10 Gbps single channel bandwidth was tested and a 1.6 Gbps aggregate bandwidth was also demonstrated through a three slot 16-channel optical backplane bus. This aggregate bandwidth was limited by an electronic element in the receiver circuit (155 Mbps PD-TIA) and processor (100 Mbps FPGA). With the system's measured optical isolation of greater than 80dB, and suitably fast receiver electronics, simulation modeling indicates that Terabit per second bus data rates can be achieved in inexpensive, mechanically robust and reliable form factors.

  13. Development of the bus joint for the ITER Central Solenoid

    SciTech Connect

    Martovetsky, Nicolai N; Irick, David Kim; Kenney, Steven J

    2013-01-01

    The terminations of the Central Solenoid (CS) modules are connected to the bus extensions by joints located outside the CS in the gap between the CS and Torodial Field (TF) assemblies. These joints have very strict space limitations. Low resistance is a common requirement for all ITER joints. In addition, the CS bus joints will experience and must be designed to withstand significant variation in the magnetic field of several tenths of a Tesla per second during initiation of plasma. The joint resistance is specified to be less than 4 nOhm. The joints also have to be soldered in the field and designed with the possibility to be installed and dismantled in order to allow cold testing in the cold test facility. We have developed coaxial joints that meet these requirements and have demonstrated the feasibility to fabricate and assemble them in the vertical configuration. We introduced a coupling cylinder with superconducting strands soldered to the surface of the cable that can be installed in the ITER assembly hall and at the Cold Test Facility. This cylinder serves as a transition area between the CS module and the bus extension. We made two racetrack samples and tested four bus joints in our Joint Test Apparatus. Resistance of the bus joints was measured by a decay method and by a microvoltmeter; the value of the current was measured by the Hall probes. This measurement method was verified in the previous tests. The resistance of the joints varied insignificantly from 1.5 to 2 nOhm. One of the challenges associated with a soldered joint is the inability to use corrosive chemicals that are difficult to clean. This paper describes our development work on cable preparation, chrome removal, compaction, soldering, and final assembly and presents the test results.

  14. Development of a composite line source emission model for traffic interrupted microenvironments and its application in particle number emissions at a bus station

    NASA Astrophysics Data System (ADS)

    Wang, Lina; Jayaratne, Rohan; Heuff, Darlene; Morawska, Lidia

    A composite line source emission (CLSE) model was developed to specifically quantify exposure levels and describe the spatial variability of vehicle emissions in traffic interrupted microenvironments. This model took into account the complexity of vehicle movements in the queue, as well as different emission rates relevant to various driving conditions (cruise, decelerate, idle and accelerate), and it utilised multi-representative segments to capture the accurate emission distribution for real vehicle flow. Hence, this model was able to quickly quantify the time spent in each segment within the considered zone, as well as the composition and position of the requisite segments based on the vehicle fleet information, which not only helped to quantify the enhanced emissions at critical locations, but it also helped to define the emission source distribution of the disrupted steady flow for further dispersion modelling. The model then was applied to estimate particle number emissions at a bi-directional bus station used by diesel and compressed natural gas fuelled buses. It was found that the acceleration distance was of critical importance when estimating particle number emission, since the highest emissions occurred in sections where most of the buses were accelerating and no significant increases were observed at locations where they idled. It was also shown that emissions at the front end of the platform were 43 times greater than at the rear of the platform. Although the CLSE model is intended to be applied in traffic management and transport analysis systems for the evaluation of exposure, as well as the simulation of vehicle emissions in traffic interrupted microenvironments, the bus station model can also be used for the input of initial source definitions in future dispersion models.

  15. Improving student bus-riding behavior through a whole-school intervention.

    PubMed

    Putnam, Robert F; Handler, Marcie W; Ramirez-Platt, Christina M; Luiselli, James K

    2003-01-01

    We describe a multicomponent intervention to improve bus-riding behavior of students attending an urban public school. The intervention was developed with technical assistance consultation that emphasized collaboration among students, school personnel, and bus drivers. The primary intervention procedures were identifying appropriate behaviors during transportation ("bus rules"), training bus drivers to deliver positive reinforcement, and rewarding student performance through a weekly school-based lottery. Disruptive bus behaviors, as measured by discipline referrals and suspensions, decreased with intervention relative to baseline phases in an ABAB reversal design. These positive results were maintained over the long term, with school personnel assuming responsibility for intervention in the absence of ongoing consultation. PMID:14768676

  16. An intelligent fiberoptic data bus for fly-by-light applications

    NASA Astrophysics Data System (ADS)

    Manoharan, L. C.; Muthuvel, S.

    An active fiberoptic data bus compatible with MIL-STD-1553B, which could be used for fly-by-light, stores management, AEW etc., on an aircraft has been developed. The data bus is considered intelligent because it can automatically sense which station is in the transmit mode and control the active interface accordingly, so that smooth flow of data takes place on the bus. The tests carried out on the bus including those on the Jaguar Avionics Rig to check its validity are also described. As no software is involved in the operation of the bus, this could be used on any aircraft having its own software.

  17. SunLine Transit Agency Advanced Technology Fuel Cell Bus Evaluation: First Results Report

    SciTech Connect

    Eudy, L.; Chandler, K.

    2011-03-01

    This report describes operations at SunLine Transit Agency for their newest prototype fuel cell bus and five compressed natural gas (CNG) buses. In May 2010, SunLine began operating its sixth-generation hydrogen fueled bus, an Advanced Technology (AT) fuel cell bus that incorporates the latest design improvements to reduce weight and increase reliability and performance. The agency is collaborating with the U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) to evaluate the bus in revenue service. This report provides the early data results and implementation experience of the AT fuel cell bus since it was placed in service.

  18. A simulation approach to MIL-STD-1553 Multiplex Bus interfacing

    NASA Astrophysics Data System (ADS)

    Lawson, R. J.; Murray, J.

    The technique developed for interfacing a 32 bit minicomputer to the MIL-STD-1553 Avionics Multiplex Bus (Mux Bus) in the F/A-18 Part Task Trainer is discussed. It is noted that the capability of access to the Mux Bus through a minicomputer provides the means of emulating any aircraft system the mission computer interfaces to in the aircraft. The capability of emulating the mission computer also exists for simulating real aircraft systems. The technique for recognizing bus requests for systems data required for simulation and responding to these requests within the timing constraints of 1553 is described, and details of bus operation specified by 1553 are given.

  19. Design of a CAN bus interface for photoelectric encoder in the spaceflight camera

    NASA Astrophysics Data System (ADS)

    Sun, Ying; Wan, Qiu-hua; She, Rong-hong; Zhao, Chang-hai; Jiang, Yong

    2009-05-01

    In order to make photoelectric encoder usable in a spaceflight camera which adopts CAN bus as the communication method, CAN bus interface of the photoelectric encoder is designed in this paper. CAN bus interface hardware circuit of photoelectric encoder consists of CAN bus controller SJA 1000, CAN bus transceiver TJA1050 and singlechip. CAN bus interface controlling software program is completed in C language. A ten-meter shield twisted pair line is used as the transmission medium in the spaceflight camera, and speed rate is 600kbps.The experiments show that: the photoelectric encoder with CAN bus interface which has the advantages of more reliability, real-time, transfer rate and transfer distance overcomes communication line's shortcomings of classical photoelectric encoder system. The system works well in automatic measuring and controlling system.

  20. Smoothed perturbation analysis algorithms for estimating the derivatives of occupancy-related functions in serial queueing networks

    NASA Technical Reports Server (NTRS)

    Wardi, Y.; Gong, W.-B.; Cassandras, C. G.; Kallmes, M. H.

    1991-01-01

    The authors present smoothed perturbation analysis (SPA) estimators for the derivative of a number of occupancy-related functions in serial queuing networks with finite buffer spaces. The functions are the average number of customers at a network as seen by an arrival, the probability that a customer is blocked at a particular queue, and the probability that a customer leaves a queue empty. In all three cases, the variable is a parameter of the distribution of service times at one of the queues. The derivative estimators considered are very simple and flexible, and they easily lend themselves to analysis of unbiasedness. Unlike most of the established SPA estimators, the present ones are not based on the computation of hazard rates.

  1. GOES-R Dual Isolation

    NASA Technical Reports Server (NTRS)

    Freesland, Doug; Carter, Delano; Chapel, Jim; Clapp, Brian; Howat, John; Krimchansky, Alexander

    2015-01-01

    The Geostationary Operational Environmental Satellite-R Series (GOES-R) is the first of the next generation geostationary weather satellites, scheduled for delivery in late 2015. GOES-R represents a quantum increase in Earth and solar weather observation capabilities, with 4 times the resolution, 5 times the observation rate, and 3 times the number of spectral bands for Earth observations. With the improved resolution, comes the instrument suite's increased sensitive to disturbances over a broad spectrum 0-512 Hz. Sources of disturbance include reaction wheels, thruster firings for station keeping and momentum management, gimbal motion, and internal instrument disturbances. To minimize the impact of these disturbances, the baseline design includes an Earth Pointed Platform (EPP), a stiff optical bench to which the two nadir pointed instruments are collocated together with the Guidance Navigation & Control (GN&C) star trackers and Inertial Measurement Units (IMUs). The EPP is passively isolated from the spacecraft bus with Honeywell D-Strut isolators providing attenuation for frequencies above approximately 5 Hz in all six degrees-of-freedom. A change in Reaction Wheel Assembly (RWA) vendors occurred very late in the program. To reduce the risk of RWA disturbances impacting performance, a secondary passive isolation system manufactured by Moog CSA Engineering was incorporated under each of the six 160 Nms RWAs, tuned to provide attenuation at frequencies above approximately 50 Hz. Integrated wheel and isolator testing was performed on a Kistler table at NASA Goddard Space Flight Center. High fidelity simulations were conducted to evaluate jitter performance for four topologies: 1) hard mounted no isolation, 2) EPP isolation only, 2) RWA isolation only, and 4) dual isolation. Simulation results demonstrate excellent performance relative to the pointing stability requirements, with dual isolated Line of Sight (LOS) jitter less than 1 micron rad.

  2. Optimal Tracking Controller Design for Active Queue Management Routers via LQ-Servo

    NASA Astrophysics Data System (ADS)

    Lee, Kang Min; Yang, Ji Hoon; Suh, Byung Suhl

    2009-01-01

    This paper proposes the LQ-Servo controller for AQM (Active Queue Management) routers. The proposed controller structure is made by taking a traditional servo mechanism based on Linear Quadratic approach and by augmenting a new state variable to the feed forward loop. Since the controller structure is consists of a standard optimal feedback regulator and a feed forward controller, it is able to enhance the usefulness of resources and to reduce unnecessary memory reservations such as RAM (Random Access Memory) or SMA (Shared Memory Area) on ordinary router systems, respectively.

  3. 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.

  4. Optimal scheduling in queueing network models of high-volume commercial web sites

    NASA Astrophysics Data System (ADS)

    Squillante, Mark S.; Xia, Cathy H.; Zhang, Li

    2001-02-01

    The optimal control of various performance-based measures in high-volume commercial web sites requires a fundamental understanding of the interactions between the diverse set of Internet services that support customer needs and the different importance levels of these services to both the customer and the e-commerce merchant. We present here a study of the control policy for each server in a multiclass queueing network that maximizes a particular function of profit, or minimizes a particular function of cost, across the different classes of Internet services.

  5. School Bus Ridership Orientation and Training. Pupil Transportation Safety Program. Implementation & Reference Guide for D.O.T. Standard 17.

    ERIC Educational Resources Information Center

    Larsen, R. A.

    Designed to assist pupil transportation supervisors, safety instructors, school bus drivers, curriculum writers, teachers, and others who have some type of responsibility for school bus safety, this suggestion-type booklet provides practical tips for educating student school bus riders. The items covered are (1) going to the bus stop; (2) at the

  6. 40 CFR 85.1404 - Maintenance of records for urban bus operators; submittal of information; right of entry.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Maintenance of records for urban bus... SOURCES Urban Bus Rebuild Requirements § 85.1404 Maintenance of records for urban bus operators; submittal of information; right of entry. (a) The operator of any urban bus for which this subpart...

  7. The transient analysis of the queue-length distribution in the batch arrival system with N-policy, multiple vacations and setup times

    NASA Astrophysics Data System (ADS)

    Kempa, Wojciech M.

    2010-10-01

    A batch arrival queueing system of the MX/G/1 type with unlimited queue is considered. After each busy period the server begins a multiple vacation period, consisting of independent single vacations, when the service process is blocked. The server begins successive single vacations as far as at the end of one of them the number of customers waiting in the queue equals at least N. The service of the first customer after the vacation period is preceded by a setup time. The analysis of the queue-size distribution on the first vacation cycle is directed to the analysis of the same characteristic in the corresponding "usual" system with unremovable server on its first busy period. The renewal-theory approach is used to obtain results in the general case. As main result the explicit representation for the LT of queue-size distribution is derived for the original system.

  8. Weak bus-oriented optimal multi-objective VAR planning

    SciTech Connect

    Chen, Y.L.

    1996-11-01

    This paper presents a weak bus-oriented criterion to determine the candidate buses for installing new VAR sources in the VAR planning problem. First, an efficient method, using a voltage collapse proximity indicator, is described for identifying weak buses. Then appropriate VAR planning in those weak buses can enhance the system security margin, in particular, to prevent voltage collapse. Next, the goal attainment (GA) method based on the Simulated Annealing (SA) approach is applied to solving general multi-objective VAR planning problems by assuming that the decisionmaker (DM) has goals for each of the objective functions. The presented method can both obtain a better final solution and reduce the solution space. Results of application of the proposed method to the AEP-14 bus system as well as to a large, actual-size system are also presented.

  9. Heat storage for a bus petrol internal-combustion engine

    NASA Astrophysics Data System (ADS)

    Vasiliev, Leonard L.; Burak, Victor S.; Kulakov, Andry G.; Mishkinis, Donatas A.; Bohan, Pavel V.

    The heat storage (HS) system for pre-heating a bus petrol internal combustion engine to starting was mathematically modelled and experimentally investigated. The development of such devices is an extremely urgent problem especially for regions with a cold climate. We discuss how HS works on the effect of absorption and rejection of heat energy at a solid-liquid phase change of a HS substance. In the first part of the paper a numerical method to calculate the HS mass-dimensional parameters and their characteristics are described. In the experimental part of the paper results are given of experiments on the pre-heating device aiding to start a carburettor engine under operational conditions and analysis of data received. Practical confirmation of the theoretical development of HS devices for a bus engine for starting by pre-heating is given.

  10. Bus Vent Design Evolution for the Solar Dynamics Observatory

    NASA Technical Reports Server (NTRS)

    Woronowicz, Michael

    2010-01-01

    As a spacecraft undergoes ascent in a launch vehicle, its pressure environment transitions from one atmosphere to high vacuum in a matter of minutes. Venting of internal cavities is necessary to prevent the buildup of pressure differentials across cavity walls. Opposing the need to vent these volumes freely into space are thermal, optical, and electrostatic requirements for limiting or prohibiting the intrusion of unwanted energy into the same cavities. Bus vent design evolution is discussed for the Solar Dynamics Observatory. Design changes were influenced by a number of factors and concerns, such as contamination control, electrostatic discharge, changes in bus material, and driving fairing ascent pressure for a launch vehicle that was just entering service as this satellite project had gotten underway.

  11. Towards ubiquitous computing in Indonesia: automated bus system

    NASA Astrophysics Data System (ADS)

    Agushinta R., Dewi; Darmayantie, Astie; Rindhayanti, Hauliza; Permatasari, Jessica; H. S, D. Suryadi

    2011-10-01

    The traffic jam becomes the biggest problem in urban area especially in Jakarta as the capital city of Indonesia. This is due to inadequate facilities of public transportation so, people prefers to use the private vehicles. The government has given the solution to enhance that but it is still not effective and it made the situation of traffic jam became worst. This paper proposed the Automated Bus System (ABS) to improve the existing system and enhance the traffic jam problem. This bus system has the ability to ride on his own without relying on any human driver. It can recognize any obstacles and avoid any collision using stereo vision technology. RFID technology is used to improve the accuracy. Still, this whole system is monitored by human operators. If there is any failure beyond the ability of system, the human operators could recognize the problem.

  12. Discharging a DC bus capacitor of an electrical converter system

    DOEpatents

    Kajouke, Lateef A; Perisic, Milun; Ransom, Ray M

    2014-10-14

    A system and method of discharging a bus capacitor of a bidirectional matrix converter of a vehicle are presented here. The method begins by electrically shorting the AC interface of the converter after an AC energy source is disconnected from the AC interface. The method continues by arranging a plurality of switching elements of a second energy conversion module into a discharge configuration to establish an electrical current path from a first terminal of an isolation module, through an inductive element, and to a second terminal of the isolation module. The method also modulates a plurality of switching elements of a first energy conversion module, while maintaining the discharge configuration of the second energy conversion module, to at least partially discharge a DC bus capacitor.

  13. Crack detection sensor layout and bus configuration analysis

    NASA Astrophysics Data System (ADS)

    Sharp, Nathan; Kuntz, Alan; Brubaker, Cole; Amos, Stephanie; Gao, Wei; Gupta, Gautam; Mohite, Aditya; Farrar, Chuck; Mascareñas, David

    2014-05-01

    In crack detection applications large sensor arrays are needed to be able to detect and locate cracks in structures. Emerging graphene-oxide paper sensing skins are a promising technology that will help enable structural sensing skins, but in order to make use of them we must consider how the sensors will be laid out and wired on the skin. This paper analyzes different sensor shapes and layouts to determine the layout which provides the preferred performance. A ‘snaked hexagon’ layout is proposed as the preferred sensor layout when both crack detection and crack location parameters are considered. In previous work we have developed a crack detection circuit which reduces the number of channels of the system by placing several sensors onto a common bus line. This helps reduce data and power consumption requirements but reduces the robustness of the system by creating the possibility of losing sensing in several sensors in the event that a single wire breaks. In this paper, sensor bus configurations are analyzed to increase the robustness of the bused sensor system. Results show that spacing out sensors in the same bus as much as possible increases the robustness of the system and that at least 3 buses are needed to prevent large segments of a structure from losing sensing in the event of a bus failure. This work is a preliminary effort toward enabling a new class of ‘networked materials’ that will be vitally important for next generation structural applications. ‘Networked materials’ have material properties related to information theoretic concepts. An example material property is ‘bandwidth’ per unit of material that might indicate the amount of information the material can provide about its state-of-health.

  14. BC Transit Fuel Cell Bus Project: Evaluation Results Report

    SciTech Connect

    Eudy, L.; Post, M.

    2014-02-01

    This report evaluates a fuel cell electric bus demonstration led by British Columbia Transit (BC Transit) in Whistler, Canada. BC Transit is collaborating with the California Air Resources Board and the U.S. Department of Energy's National Renewable Energy Laboratory to evaluate the buses in revenue service. This evaluation report covers two years of revenue service data on the buses from April 2011 through March 2013.

  15. Violence against metropolitan bus drivers and fare collectors in Brazil

    PubMed Central

    Assunção, Ada Ávila; de Medeiros, Adriane Mesquita

    2015-01-01

    OBJECTIVE To analyze the correlation between sociodemographic factors and working conditions of bus workers in a metropolitan area and violence against them. METHODS This cross-sectional study used a nonprobabilistic sample estimated according to the number of workers employed in bus companies located in three cities in the Belo Horizonte metropolitan region in 2012 (N = 17,470). Face-to-face interviews were conducted using a digital questionnaire. The factors associated with violence were analyzed in two stages using Poisson regression, according to each level. The magnitude of the association was evaluated using prevalence ratios with robust variance and a statistical significance of 5%, and 95% confidence intervals were obtained. RESULTS The study sample comprised 782 drivers and 691 fare collectors; 45.0% participants reported at least one act of violence in the workplace in the last 12 months, with passengers being predominantly responsible. The age of the bus workers was inversely associated with violence. Chronic diseases, sickness absenteeism, and working conditions were also associated with violence. CONCLUSIONS The findings on the correlation between violence and working conditions are essential for implementing prevention strategies by transportation service managers. PMID:25741657

  16. Safety evaluation of a hydrogen fueled transit bus

    SciTech Connect

    Coutts, D.A.; Thomas, J.K.; Hovis, G.L.; Wu, T.T.

    1997-12-31

    Hydrogen fueled vehicle demonstration projects must satisfy management and regulator safety expectations. This is often accomplished using hazard and safety analyses. Such an analysis has been completed to evaluate the safety of the H2Fuel bus to be operated in Augusta, Georgia. The evaluation methods and criteria used reflect the Department of Energy`s graded approach for qualifying and documenting nuclear and chemical facility safety. The work focused on the storage and distribution of hydrogen as the bus motor fuel with emphases on the technical and operational aspects of using metal hydride beds to store hydrogen. The safety evaluation demonstrated that the operation of the H2Fuel bus represents a moderate risk. This is the same risk level determined for operation of conventionally powered transit buses in the United States. By the same criteria, private passenger automobile travel in the United States is considered a high risk. The evaluation also identified several design and operational modifications that resulted in improved safety, operability, and reliability. The hazard assessment methodology used in this project has widespread applicability to other innovative operations and systems, and the techniques can serve as a template for other similar projects.

  17. Pilot Survey of Subway and Bus Stop Noise Levels

    PubMed Central

    Neitzel, Richard; Barrera, Marissa A.; Akram, Muhammad

    2006-01-01

    Excessive noise exposure is a serious global urban health problem, adversely affecting millions of people. One often cited source of urban noise is mass transit, particularly subway systems. As a first step in determining risk within this context, we recently conducted an environmental survey of noise levels of the New York City transit system. Over 90 noise measurements were made using a sound level meter. Average and maximum noise levels were measured on subway platforms, and maximum levels were measured inside subway cars and at several bus stops for comparison purposes. The average noise level measured on the subway platforms was 86 ± 4 dBA (decibel-A weighting). Maximum levels of 106, 112, and 89 dBA were measured on subway platforms, inside subway cars, and at bus stops, respectively. These results indicate that noise levels in subway and bus stop environments have the potential to exceed recommended exposure guidelines from the World Health Organization (WHO) and U.S. Environmental Protection Agency (EPA), given sufficient exposure duration. Risk reduction strategies following the standard hierarchy of control measures should be applied, where feasible, to reduce subway noise exposure. PMID:16802179

  18. A Dimensional Bus model for integrating clinical and research data

    PubMed Central

    Hum, Richard C; Murphy, James R

    2011-01-01

    Objectives Many clinical research data integration platforms rely on the Entity–Attribute–Value model because of its flexibility, even though it presents problems in query formulation and execution time. The authors sought more balance in these traits. Materials and Methods Borrowing concepts from Entity–Attribute–Value and from enterprise data warehousing, the authors designed an alternative called the Dimensional Bus model and used it to integrate electronic medical record, sponsored study, and biorepository data. Each type of observational collection has its own table, and the structure of these tables varies to suit the source data. The observational tables are linked to the Bus, which holds provenance information and links to various classificatory dimensions that amplify the meaning of the data or facilitate its query and exposure management. Results The authors implemented a Bus-based clinical research data repository with a query system that flexibly manages data access and confidentiality, facilitates catalog search, and readily formulates and compiles complex queries. Conclusion The design provides a workable way to manage and query mixed schemas in a data warehouse. PMID:21856687

  19. Design and analysis of a Virtual-Bus Interconnection Network

    SciTech Connect

    Park, Y.K.

    1987-01-01

    An efficient communication system - named the Virtual-Bus Interconnection Network (VIN) - for multiple instruction, multiple data-type loosely coupled parallel computers is presented. The VIN is designed to take advantage of the principle of the information-processing locality, which implies greater interactions between closely related tasks. This is accomplished through the use of interconnecting multiple buses in a multilevel hierarchical structure and interleaving bit-synchronized communications. Each node of the system has two physical connections: one for the upper-link bus and the other for the lower-link bus. By combining time division and priority-based, contention-free multiaccess protocols, the VIN provides logical full connectivity to the processors without direct physical connections. Thus, the VIN exhibits a high degree of extensibility and modularity. A collective evaluation formula was developed, and the performance of the WIN was analyzed and compared with other schemes. The analysis shows that the performance of the VIN is superior to other schemes when algorithms exhibit the locality of the communication patterns.

  20. Violence against metropolitan bus drivers and fare collectors in Brazil.

    PubMed

    Assunção, Ada Ávila; Medeiros, Adriane Mesquita de

    2015-01-01

    OBJECTIVE To analyze the correlation between sociodemographic factors and working conditions of bus workers in a metropolitan area and violence against them. METHODS This cross-sectional study used a nonprobabilistic sample estimated according to the number of workers employed in bus companies located in three cities in the Belo Horizonte metropolitan region in 2012 (N = 17,470). Face-to-face interviews were conducted using a digital questionnaire. The factors associated with violence were analyzed in two stages using Poisson regression, according to each level. The magnitude of the association was evaluated using prevalence ratios with robust variance and a statistical significance of 5%, and 95% confidence intervals were obtained. RESULTS The study sample comprised 782 drivers and 691 fare collectors; 45.0% participants reported at least one act of violence in the workplace in the last 12 months, with passengers being predominantly responsible. The age of the bus workers was inversely associated with violence. Chronic diseases, sickness absenteeism, and working conditions were also associated with violence. CONCLUSIONS The findings on the correlation between violence and working conditions are essential for implementing prevention strategies by transportation service managers. PMID:25741657

  1. Ring Bus Architecture for a Solid-State Recorder

    NASA Technical Reports Server (NTRS)

    Walker, W. John; Kopf, Edward; Cox, Brian

    2008-01-01

    A document concisely describes a ring bus architecture for a proposed solid-state recorder (SSR) that would serve as buffer of data to be transmitted from a spacecraft to Earth. This architecture would afford fault tolerance needed for reliable operation in an anticipated high-radiation environment in which traditional SSRs cannot operate reliably. Features of the architecture include one or more controller boards and multiple memory boards interconnected in a ringlike topology. The interconnections would be high-speed serial links complying with the Institute of Electrical and Electronics Engineers (IEEE) standard 1393 (which pertains to a spaceborne fiber-optic data bus). Accordingly, each controller and memory board would be equipped with an IEEE-1393-compliant ring-bus-interface unit. The ringlike topology and the multiplicity of memory boards (and, optionally, of controller boards) would afford the redundancy needed for fault tolerance. Each board would be a fault-containment region. The IEEE 1393 links could be routed so that the SSR would continue to function even in the event of multiple failures. This architecture would also support scalability over a wide range. In a fully redundant configuration, it could accommodate between 1 and 125 memory boards.

  2. The AI Bus architecture for distributed knowledge-based systems

    NASA Technical Reports Server (NTRS)

    Schultz, Roger D.; Stobie, Iain

    1991-01-01

    The AI Bus architecture is layered, distributed object oriented framework developed to support the requirements of advanced technology programs for an order of magnitude improvement in software costs. The consequent need for highly autonomous computer systems, adaptable to new technology advances over a long lifespan, led to the design of an open architecture and toolbox for building large scale, robust, production quality systems. The AI Bus accommodates a mix of knowledge based and conventional components, running on heterogeneous, distributed real world and testbed environment. The concepts and design is described of the AI Bus architecture and its current implementation status as a Unix C++ library or reusable objects. Each high level semiautonomous agent process consists of a number of knowledge sources together with interagent communication mechanisms based on shared blackboards and message passing acquaintances. Standard interfaces and protocols are followed for combining and validating subsystems. Dynamic probes or demons provide an event driven means for providing active objects with shared access to resources, and each other, while not violating their security.

  3. Simulating performance impacts of bus lanes and supporting measures

    SciTech Connect

    Shalaby, A.S.

    1999-10-01

    This study used the TRANSYT-7F simulator to examine changes in performance measures of through buses and adjacent traffic following the introduction of reserved lanes in an urban arterial. In addition, the TRANSYT-7F simulator was used to examine the specific impacts on modal performance of two policy measures implemented in conjunction with lane introduction. The results showed that TRANSYT-7F provided relatively accurate estimates of bus delays and auto speeds. However, the study identified one area of improvement for TRANSYT-7F to model priority treatments on arterials more effectively. The simulation results showed that the performance of the average bus improved after project implementation, whereas the performance of the adjacent through traffic deteriorated. However, the deterioration exceeded the improvement. Other aggregate estimates of performance were examined and discussed. The simulations also showed that modifications to left-turn movements would have a minor impact on both bus and adjacent traffic performance, whereas the removal of taxis from the reserved lanes would cause far more performance deterioration to the adjacent traffic than the performance improvement this policy measure would bring to buses.

  4. MIL-STD-1553 BUS exerciser/tester

    NASA Astrophysics Data System (ADS)

    Friedman, S. N.

    The BUS-68000 Exerciser functions as a fully programmable bus controller or can simulate remote terminals. It is a low-cost portable instrument for testing and troubleshooting MIL-STD-1553 systems. It can simulate all MIL-STD-1553 message formats and provides up to eight message blocks (up to 49 words deep in each). Keyboard and display function are tabulated in detail, along with pin functions. The front panel keyboard and display or IEEE-488 and RS-232 optional I/O ports are available for ease of programming. Five programming examples are given. Encoder error injection and format error injection are easily achieved. Format and word error detection are indicated by front panel LEDs and an error code display. With the RS-232 option, the BUS-68000 can print out the entire block on a CRT or hardcopy printer to permit a complete preview of each message block, including the programmed encoder errors. It is then possible to review the programmed encoder errors. It is then possible to review the message blocks after the transfer to obtain data information and errors encoded or detected.

  5. Queueing induced by bidirectional motor motion near the end of a microtubule

    NASA Astrophysics Data System (ADS)

    Ashwin, Peter; Lin, Congping; Steinberg, Gero

    2010-11-01

    Recent live observations of motors in long-range microtubule (MT) dependent transport in the fungus Ustilago maydis have reported bidirectional motion of dynein and an accumulation of the motors at the polymerization-active (the plus-end) of the microtubule. Quantitative data derived from in vivo observation of dynein has enabled us to develop an accurate, quantitatively-valid asymmetric simple exclusion process (ASEP) model that describes the coordinated motion of anterograde and retrograde motors sharing a single oriented microtubule. We give approximate expressions for the size and distribution of the accumulation, and discuss queueing properties for motors entering this accumulation. We show for this ASEP model, that the mean accumulation can be modeled as an M/M/∞ queue that is Poisson distributed with mean Farr/pd , where Farr is the flux of motors that arrives at the tip and pd is the rate at which individual motors change direction from anterograde to retrograde motion. Deviations from this can in principle be used to gain information about other processes at work in the accumulation. Furthermore, our work is a significant step toward a mathematical description of the complex interactions of motors in cellular long-range transport of organelles.

  6. Handover Management for VoWLAN Based on Estimation of AP Queue Length and Frame Retries

    NASA Astrophysics Data System (ADS)

    Niswar, Muhammad; Kashihara, Shigeru; Tsukamoto, Kazuya; Kadobayashi, Youki; Yamaguchi, Suguru

    Switching a communication path from one Access Point (AP) to another in inter-domain WLANs is a critical challenge for delay-sensitive applications such as Voice over IP (VoIP) because communication quality during handover (HO) is more likely to be deteriorated. To maintain VoIP quality during HO, we need to solve many problems. In particular, in bi-directional communication such as VoIP, an AP becomes a bottleneck with the increase of VoIP calls. As a result, packets queued in the AP buffer may experience a large queuing delay or packet losses due to increase in queue length or buffer overflow, thereby causing the degradation of VoIP quality for the Mobile Nodes (MNs) side. To avoid this degradation, MNs need to appropriately and autonomously execute HO in response to the change in wireless network condition, i.e., the deterioration of wireless link quality and the congestion state at the AP. In this paper, we propose an HO decision strategy considering frame retries, AP queue length, and transmission rate at an MN for maintaining VoIP quality during HO. Through simulation experiments, we then show that our proposed method can maintain VoIP quality during HO by properly detecting the wireless network condition.

  7. An Optimization Model for the Selection of Bus-Only Lanes in a City

    PubMed Central

    Chen, Qun

    2015-01-01

    The planning of urban bus-only lane networks is an important measure to improve bus service and bus priority. To determine the effective arrangement of bus-only lanes, a bi-level programming model for urban bus lane layout is developed in this study that considers accessibility and budget constraints. The goal of the upper-level model is to minimize the total travel time, and the lower-level model is a capacity-constrained traffic assignment model that describes the passenger flow assignment on bus lines, in which the priority sequence of the transfer times is reflected in the passengers’ route-choice behaviors. Using the proposed bi-level programming model, optimal bus lines are selected from a set of candidate bus lines; thus, the corresponding bus lane network on which the selected bus lines run is determined. The solution method using a genetic algorithm in the bi-level programming model is developed, and two numerical examples are investigated to demonstrate the efficacy of the proposed model. PMID:26214001

  8. Development and validation of a self-report measure of bus driver behaviour.

    PubMed

    Dorn, Lisa; Stephen, Lucy; af Wåhlberg, Anders; Gandolfi, Julie

    2010-12-01

    There are likely to be individual differences in bus driver behaviour when adhering to strict schedules under time pressure. A reliable and valid assessment of these individual differences would be useful for bus companies keen to mitigate risk of crash involvement. This paper reports on three studies to develop and validate a self-report measure of bus driver behaviour. For study 1, two principal components analyses of a pilot questionnaire revealed six components describing bus driver behaviour and four bus driver coping components. In study 2, test-retest reliability of the components were tested in a sub-sample and found to be adequate. Further, the 10 components were used to predict bus crash involvement at three levels of culpability with consistently significant associations found for two components. For study 3, avoidance coping was consistently associated with celeration variables in a bus simulator, especially for a time-pressured drive. STATEMENT OF RELEVANCE: The instrument can be used by bus companies for driver stress and fatigue management training to identify at-risk bus driver behaviour. Training to reduce the tendency to engage in avoidance coping strategies, improve evaluative coping strategies and hazard monitoring when under stress may improve bus driver safety. PMID:21108079

  9. Common Traffic Violations of Bus Drivers in Urban China: An Observational Study

    PubMed Central

    Yang, Rendong; Huang, Yuanxiu; Zhang, Lin; Ning, Peishan; Cheng, Xunjie; Schwebel, David C.

    2015-01-01

    Objective To report common traffic violations in bus drivers and the factors that influence those violations in urban China. Methods We conducted an observational study to record three types of traffic violations among bus drivers in Changsha City, China: illegal stopping at bus stations, violating traffic light signals, and distracted driving. The behaviors of bus drivers on 32 routes (20% of bus routes in the city) were observed. A two-level Poisson regression examined factors that predicted bus driver violations. Results The incidence of illegal stopping at bus stations was 20.2%. Illegal stopping was less frequent on weekends, sunny days, and at stations with cameras, with adjusted incidence rate ratios (IRRs) of 0.81, 0.65 and 0.89, respectively. The incidence of violating traffic light signals was 2.2%, and was lower on cloudy than sunny days (adjusted IRR: 0.60). The incidence of distracted driving was 3.3%. The incidence of distracted driving was less common on cloudy days, rainy or snowy days, and foggy/windy/dusty days compared to sunny days, with adjusted IRRs of 0.54, 0.55 and 0.07, respectively. Conclusion Traffic violations are common in bus drivers in urban China and they are associated with the date, weather, and presence of traffic cameras at bus station. Further studies are recommended to understand the behavioral mechanisms that may explain bus driver violations and to develop feasible prevention measures. PMID:26372105

  10. An Optimization Model for the Selection of Bus-Only Lanes in a City.

    PubMed

    Chen, Qun

    2015-01-01

    The planning of urban bus-only lane networks is an important measure to improve bus service and bus priority. To determine the effective arrangement of bus-only lanes, a bi-level programming model for urban bus lane layout is developed in this study that considers accessibility and budget constraints. The goal of the upper-level model is to minimize the total travel time, and the lower-level model is a capacity-constrained traffic assignment model that describes the passenger flow assignment on bus lines, in which the priority sequence of the transfer times is reflected in the passengers' route-choice behaviors. Using the proposed bi-level programming model, optimal bus lines are selected from a set of candidate bus lines; thus, the corresponding bus lane network on which the selected bus lines run is determined. The solution method using a genetic algorithm in the bi-level programming model is developed, and two numerical examples are investigated to demonstrate the efficacy of the proposed model. PMID:26214001

  11. Delay Analysis of Max-Weight Queue Algorithm for Time-Varying Wireless Ad hoc Networks—Control Theoretical Approach

    NASA Astrophysics Data System (ADS)

    Chen, Junting; Lau, Vincent K. N.

    2013-01-01

    Max weighted queue (MWQ) control policy is a widely used cross-layer control policy that achieves queue stability and a reasonable delay performance. In most of the existing literature, it is assumed that optimal MWQ policy can be obtained instantaneously at every time slot. However, this assumption may be unrealistic in time varying wireless systems, especially when there is no closed-form MWQ solution and iterative algorithms have to be applied to obtain the optimal solution. This paper investigates the convergence behavior and the queue delay performance of the conventional MWQ iterations in which the channel state information (CSI) and queue state information (QSI) are changing in a similar timescale as the algorithm iterations. Our results are established by studying the stochastic stability of an equivalent virtual stochastic dynamic system (VSDS), and an extended Foster-Lyapunov criteria is applied for the stability analysis. We derive a closed form delay bound of the wireless network in terms of the CSI fading rate and the sensitivity of MWQ policy over CSI and QSI. Based on the equivalent VSDS, we propose a novel MWQ iterative algorithm with compensation to improve the tracking performance. We demonstrate that under some mild conditions, the proposed modified MWQ algorithm converges to the optimal MWQ control despite the time-varying CSI and QSI.

  12. Testing and Evaluation of Batteries for a Fuel Cell Powered Hybrid Bus

    SciTech Connect

    Miller, J.F.; Webster, C.E.; Tummillo, A.F.; DeLuca, W.H.

    1997-05-01

    Argonne National Laboratory conducted performance characterization and life-cycle tests on various batteries to qualify them for use in a fuel cell/battery hybrid bus. On this bus, methanol-fueled, phosphoric acid fuel cells provide routine power needs, while batteries are used to store energy recovered during bus braking and to produce short-duration power during acceleration. Argonne carried out evaluation and endurance testing on several lead-acid and nickel/cadmium batteries selected by the bus developer as potential candidates for the bus application. Argonne conducted over 10,000 hours of testing, simulating more than 80,000 miles of fuel cell bus operation, for the nickel/cadmium battery, which was ultimately selected for use in the three hybrid buses built under the direction of H-Power Corp.

  13. Complex motion of a shuttle bus between two terminals with periodic inflows

    NASA Astrophysics Data System (ADS)

    Nagatani, Takashi

    2016-05-01

    We investigate the dynamic behavior of a shuttle bus serving repeatedly between two terminals when passengers come periodically at two terminals A and B. The period and phase of the periodic inflow of passengers at terminal A are different from those at terminal B. The dynamic behavior of the bus is highly affected by the difference between two periods and the phase difference. The bus schedule is closely related to the dynamics. We present the extended circle map model for the dynamics of the shuttle bus. The motion of the shuttle bus depends highly on the inflow periods, the period difference, the phase difference, and the loading parameter. The shuttle bus displays the periodic, quasi-periodic, and chaotic motions. The quasi-periodic motion changes to a chaotic motion by the difference between two periods.

  14. SunLine Transit Agency Advanced Technology Fuel Cell Bus Evaluation: Third Results Reports

    SciTech Connect

    Eudy, L.; Chandler, K.

    2012-05-01

    This report describes operations at SunLine Transit Agency for their newest prototype fuel cell bus and five compressed natural gas (CNG) buses. In May 2010, SunLine began operating its sixth-generation hydrogen fueled bus, an Advanced Technology (AT) fuel cell bus that incorporates the latest design improvements to reduce weight and increase reliability and performance. The agency is collaborating with the U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) to evaluate the bus in revenue service. NREL has previously published two reports documenting the operation of the fuel cell bus in service. This report provides a summary of the results with a focus on the bus operation from July 2011 through January 2012.

  15. SunLine Transit Agency Advanced Technology Fuel Cell Bus Evaluation: Fourth Results Report

    SciTech Connect

    Eudy, L.; Chandler, K.

    2013-01-01

    SunLine Transit Agency, which provides public transit services to the Coachella Valley area of California, has demonstrated hydrogen and fuel cell bus technologies for more than 10 years. In May 2010, SunLine began demonstrating the advanced technology (AT) fuel cell bus with a hybrid electric propulsion system, fuel cell power system, and lithium-based hybrid batteries. This report describes operations at SunLine for the AT fuel cell bus and five compressed natural gas buses. The U.S. Department of Energy's National Renewable Energy Laboratory (NREL) is working with SunLine to evaluate the bus in real-world service to document the results and help determine the progress toward technology readiness. NREL has previously published three reports documenting the operation of the fuel cell bus in service. This report provides a summary of the results with a focus on the bus operation from February 2012 through November 2012.

  16. A PRACTICAL STUDY ON APPLICABILITY OF THE INCENTIVE SUBSIDY TO BUS NETWORK IN KUMAMOTO CITY

    NASA Astrophysics Data System (ADS)

    Mizokami, Shoshi; Fujimi, Toshio; Hirano, Toshihiko

    Recently, the number of passenger of public bus services in Japan tends to decrease due to the motorization. This condition leads to a severe management situation, including in Kumamoto City. Since 1984, the deficit of bus companies operation in provision of bus services in Kumamoto has been covered by Kumamoto City Government on the basis of lines subsidy, and the city allocated a number of subsidy of about 200 million yen in 2007. Currently, The Kumamoto city government plans to reduce the amount of subsidy to bus companies by introducing the giving of incentive to bus companies in order to trim bus company deficit. This study aims to construct the mathematical model of the incentive reward and apply the model to realignment of buses lines networks in Kumamoto Metropolitan Area.

  17. A study of multiplex data bus techniques for the space shuttle

    NASA Technical Reports Server (NTRS)

    Kearney, R. J.; Kalange, M. A.

    1972-01-01

    A comprehensive technology base for the design of a multiplexed data bus subsystem is provided. Extensive analyses, both analytical and empirical, were performed. Subjects covered are classified under the following headings: requirements identification and analysis; transmission media studies; signal design and detection studies; synchronization, timing, and control studies; user-subsystem interface studies; operational reliability analyses; design of candidate data bus configurations; and evaluation of candidate data bus designs.

  18. Multi-access fiber optic data bus using FDM/FSK

    NASA Technical Reports Server (NTRS)

    Zanger, H.

    1984-01-01

    The major thrust was to develop a T coupler with very low (0.1 0.2dB) in-line loss. This is essential to any multiaccess bus structure where the word multi implies fifteen or more nodes on the bus, and it is tacitly assumed to be a passive bus. (Reliability considerations tend to exclude the use of active nodes - repeater nodes.)

  19. Small Explorer Data System MIL-STD-1773 fiber optic bus

    NASA Technical Reports Server (NTRS)

    Flanegan, Mark; Label, Ken

    1992-01-01

    The MIL-STD-1773 Fiber Optic Data Bus as implemented in the GSFC Small Explorer Data System (SEDS) for the Small Explorer Program is described. It provides an overview of the SEDS MIL-STD-1773 bus components system design considerations, reliability figures, acceptance and qualification testing requirements, radiation requirements and tests, error handling considerations, and component heritage. The first mission using the bus will be launched in June of 1992.

  20. Small Explorer Data System MIL-STD-1773 fiber optic bus

    NASA Astrophysics Data System (ADS)

    Flanegan, Mark; Label, Ken

    1992-06-01

    The MIL-STD-1773 Fiber Optic Data Bus as implemented in the GSFC Small Explorer Data System (SEDS) for the Small Explorer Program is described. It provides an overview of the SEDS MIL-STD-1773 bus components system design considerations, reliability figures, acceptance and qualification testing requirements, radiation requirements and tests, error handling considerations, and component heritage. The first mission using the bus will be launched in June of 1992.

  1. 46 CFR 112.05-3 - Main-emergency bus-tie.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Main-emergency bus-tie. 112.05-3 Section 112.05-3 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING EMERGENCY LIGHTING AND POWER SYSTEMS General § 112.05-3 Main-emergency bus-tie. Each bus-tie between a main switchboard and an emergency switchboard must:...

  2. Analysis of bus passenger comfort perception based on passenger load factor and in-vehicle time.

    PubMed

    Shen, Xianghao; Feng, Shumin; Li, Zhenning; Hu, Baoyu

    2016-01-01

    Although bus comfort is a crucial indicator of service quality, existing studies tend to focus on passenger load and ignore in-vehicle time, which can also affect passengers' comfort perception. Therefore, by conducting surveys, this study examines passengers' comfort perception while accounting for both factors. Then, using the survey data, it performs a two-way analysis of variance and shows that both in-vehicle time and passenger load significantly affect passenger comfort. Then, a bus comfort model is proposed to evaluate comfort level, followed by a sensitivity analysis. The method introduced in this study has theoretical implications for bus operators attempting to improve bus service quality. PMID:26839755

  3. Superconducting link bus design for the accelerator project for upgrade of LHC

    NASA Astrophysics Data System (ADS)

    Nobrega, Alfred; Brandt, Jeff; Cheban, Sergey; Feher, Sandor; Kaducak, Mark; Kashikhin, Vadim; Peterson, Thomas J.

    2012-06-01

    The Accelerator Project for Upgrade of LHC (APUL) is a U.S. project participating in and contributing to CERN's Large Hadron Collider (LHC) upgrade program. FermiNational Accelerator Laboratory in collaboration with Brookhaven National Laboratorywas developing sub-systems for the upgrade of the LHC final focus magnet systems. Partof the upgrade called for various lengths of superconducting power transmission linesknown as Superconducting (SC) Links which were up to 100 m long. The SC Linkelectrically connects the current leads in the Distribution Feed Boxes to the interactionregion magnets. The SC Link is an extension of the magnet bus housed within a cryostat.The present concept for the bus consists of 22 power cables, 4 × 13 kA, 2 × 7 kA, 8 × 2.5kA and 8 × 0.6 kA bundled into one bus. Different cable and strand possibilities were considered for the bus design including Rutherford cable. The Rutherford cable bus designpotentially would have required splices at each sharp elbow in the SC Link. The advantage of the round bus design is that splices are only required at each end of the bus duringinstallation at CERN. The round bus is very flexible and is suitable for pulling through thecryostat. Development of the round bus prototype and of 2 splice designs is described in this paper. Magnetic analysis and mechanical test results of the 13 kA cable and splices are presented.

  4. Analyzing the Relationship Between Bus Pollution Policies and Morbidity Using a Quasi-Experiment.

    PubMed

    Ngo, Nicole S

    2015-09-01

    Transit buses are used by millions of commuters every day, but they emit toxic diesel fumes. In 1988, the U.S. Environmental Protection Agency implemented emission standards for transit buses, which have been continually updated. Yet there is no quantitative evidence of the health benefits from these bus pollution policies due to data constraints and confounding variables. In this study, a quasi-experiment is used to exploit the geographic and temporal variation in emission standards by using bus vintage as a proxy for bus emissions. This is accomplished using a unique, rich panel data set, which includes daily information on bus vintage and route for the New York City Transit bus fleet between 2006 and 2009. This information is merged with daily data on emergency department (ED) visits for respiratory illnesses, which include patients' residences at the census block level and exact admission date. Economic benefits resulting from these bus pollution policies are then estimated. Results show that stricter transit bus emission standards by the U.S. Environmental Protection Agency for particulate matter are associated with reduced ED visits for respiratory diseases for patients living within a few hundred feet of a bus route. These findings demonstrate that bus pollution policies have made critical improvements to public health. PMID:26376392

  5. Development of Flexible Standard Bus for ISAS/JAXA Small Scientific Satellite Series

    NASA Astrophysics Data System (ADS)

    Nakaya, Koji; Fukuda, Seisuke; Sakai, Shin-Ichiro; Yamazaki, Atsushi; Uemizu, Kazunori; Toriumi, Tsuyoshi; Junko Takahashi; Maehara, Masaki; Okahashi, Takakazu; Shujiro Sawai, And

    This paper describes design and current developing status of a flexible standard bus system for a new series of small scientific satellites planned in the Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (ISAS/JAXA). The satellite series are called SPRINT series, which stands for “Small space science Platform for Rapid INvestigation and Test”. First, features realizing a flexible standard bus are mentioned. Design concepts such as alternative options and selectable options are introduced. Second, the current status of the standard bus and SPRINT-A, which is the first satellite of SPRINT series using the standard bus and planed to be launched in 2013, is explained.

  6. An Interactive Wireless Communication System for Visually Impaired People Using City Bus Transport

    PubMed Central

    Wang, Hsiao-Lan; Chen, Ya-Ping; Rau, Chi-Lun; Yu, Chung-Huang

    2014-01-01

    Visually impaired people have difficulty accessing information about public transportation systems. Several systems have been developed for assisting visually impaired and blind people to use the city bus. Most systems provide only one-way communication and require high-cost and complex equipment. The purpose of this study is to reduce the difficulties faced by visually impaired people when taking city buses, using an interactive wireless communication system. The system comprised a user module and a bus module to establish a direct one-to-one connection. When the user inputs 4-digit numbers, the user module immediately sends out the information. If the bus module receives the matched bus number, it buzzes and the warning LED flashes to notify the bus driver that someone is waiting to board on the bus. User tests were conducted by two visually impaired people in a simulated vehicle and a city bus. The success rate of interactive wireless communication, recognizing the arrival of the bus and boarding the correct bus reached 100% in all of the tests. The interactive wireless communication aid system is a valid and low-cost device for assisting visually impaired people to use city buses. PMID:24776720

  7. Analyzing the Relationship Between Bus Pollution Policies and Morbidity Using a Quasi-Experiment

    PubMed Central

    Ngo, Nicole S.

    2015-01-01

    Abstract Transit buses are used by millions of commuters every day, but they emit toxic diesel fumes. In 1988, the U.S. Environmental Protection Agency implemented emission standards for transit buses, which have been continually updated. Yet there is no quantitative evidence of the health benefits from these bus pollution policies due to data constraints and confounding variables. In this study, a quasi-experiment is used to exploit the geographic and temporal variation in emission standards by using bus vintage as a proxy for bus emissions. This is accomplished using a unique, rich panel data set, which includes daily information on bus vintage and route for the New York City Transit bus fleet between 2006 and 2009. This information is merged with daily data on emergency department (ED) visits for respiratory illnesses, which include patients’ residences at the census block level and exact admission date. Economic benefits resulting from these bus pollution policies are then estimated. Results show that stricter transit bus emission standards by the U.S. Environmental Protection Agency for particulate matter are associated with reduced ED visits for respiratory diseases for patients living within a few hundred feet of a bus route. These findings demonstrate that bus pollution policies have made critical improvements to public health. PMID:26376392

  8. Heisenberg spin bus as a robust transmission line for quantum-state transfer

    SciTech Connect

    Oh, Sangchul; Hu Xuedong; Wu Lianao; Shim, Yun-Pil; Fei, Jianjia; Friesen, Mark

    2011-08-15

    We study quantum-state transfer (QST) through a strongly coupled antiferromagnetic spin chain (acting as a spin bus), between weakly coupled external qubits. By treating the weak coupling as a perturbation, we find that QST is enabled specifically by the second-order terms in the perturbative expansion. We show that QST is robust against disorder in the couplings, either within the bus or to the external qubits. We find that the protocol works when the qubits are attached to any node on an even-size bus or to the antiferromagnetic nodes on an odd-size bus. The optimal time for QST is found to depend nonmonotonically on qubit separation.

  9. Superconducting link bus design for the accelerator project for upgrade of LHC

    SciTech Connect

    Nobrega, F.; Brandt, J.; Cheban, S.; Feher, S.; Kaducak, M.; Kashikhin, V.; Peterson, T.; /Fermilab

    2010-08-01

    The Accelerator Project for Upgrade of LHC (APUL) is a U.S. project participating in and contributing to CERN's Large Hadron Collider (LHC) upgrade program. Fermi National Accelerator Laboratory in collaboration with Brookhaven National Laboratory was developing sub-systems for the upgrade of the LHC final focus magnet systems. Part of the upgrade called for various lengths of superconducting power transmission lines known as SC Links which were up to 100 m long. The SC Link electrically connects the current leads in the Distribution Feed Boxes to the interaction region magnets. The SC Link is an extension of the magnet bus housed within a cryostat. The present concept for the bus consists of 22 power cables, 4 x 13 kA, 2 x 7 kA, 8 x 2.5 kA and 8 x 0.6 kA bundled into one bus. Different cable and strand possibilities were considered for the bus design including Rutherford cable. The Rutherford cable bus design potentially would have required splices at each sharp elbow in the SC Link. The advantage of the round bus design is that splices are only required at each end of the bus during installation at CERN. The round bus is very flexible and is suitable for pulling through the cryostat. Development of the round bus prototype and of 2 splice designs is described in this paper. Magnetic analysis and mechanical test results of the 13 kA cable and splices are presented.

  10. Superconducting link bus design for the accelerator project for upgrade of LHC

    SciTech Connect

    Nobrega, F.; Brandt, J.; Cheban, S.; Feher, S.; Kaducak, M.; Kashikhin, V.; Peterson, T.; /Fermilab

    2011-06-01

    The Accelerator Project for Upgrade of LHC (APUL) is a U.S. project participating in and contributing to CERN's Large Hadron Collider (LHC) upgrade program. Fermi National Accelerator Laboratory in collaboration with Brookhaven National Laboratory was developing sub-systems for the upgrade of the LHC final focus magnet systems. Part of the upgrade called for various lengths of superconducting power transmission lines known as SC Links which were up to 100 m long. The SC Link electrically connects the current leads in the Distribution Feed Boxes to the interaction region magnets. The SC Link is an extension of the magnet bus housed within a cryostat. The present concept for the bus consists of 22 power cables, 4 x 13 kA, 2 x 7 kA, 8 x 2.5 kA and 8 x 0.6 kA bundled into one bus. Different cable and strand possibilities were considered for the bus design including Rutherford cable. The Rutherford cable bus design potentially would have required splices at each sharp elbow in the SC Link. The advantage of the round bus design is that splices are only required at each end of the bus during installation at CERN. The round bus is very flexible and is suitable for pulling through the cryostat. Development of the round bus prototype and of 2 splice designs is described in this paper. Magnetic analysis and mechanical test results of the 13 kA cable and splices are presented.

  11. DIMETHYL ETHER (DME)-FUELED SHUTTLE BUS DEMONSTRATION PROJECT

    SciTech Connect

    Elana M. Chapman; Shirish Bhide; Jennifer Stefanik; Andre L. Boehman; David Klinikowski

    2003-04-01

    The objectives of this research and demonstration program are to convert a campus shuttle bus to operation on dimethyl ether, a potential ultra-clean alternative diesel fuel. To accomplish this objective, this project includes laboratory evaluation of a fuel conversion strategy, as well as, field demonstration of the DME-fueled shuttle bus. Since DME is a fuel with no lubricity (i.e., it does not possess the lubricating quality of diesel fuel), conventional fuel delivery and fuel injection systems are not compatible with dimethyl ether. Therefore, to operate a diesel engine on DME one must develop a fuel-tolerant injection system, or find a way to provide the necessary lubricity to the DME. In this project, they have chosen the latter strategy in order to achieve the objective with minimal need to modify the engine. The strategy is to blend DME with diesel fuel, to obtain the necessary lubricity to protect the fuel injection system and to achieve low emissions. The laboratory studies have included work with a Navistar V-8 turbodiesel engine, demonstration of engine operation on DME-diesel blends and instrumentation for evaluating fuel properties. The field studies have involved performance, efficiency and emissions measurements with the Champion Motorcoach ''Defender'' shuttle bus which will be converted to DME-fueling. The results include baseline emissions, performance and combustion measurements on the Navistar engine for operation on a federal low sulfur diesel fuel (300 ppm S). Most recently, they have completed engine combustion studies on DME-diesel blends up to 30 wt% DME addition.

  12. Implementation of PMSM speed control software based on CAN bus

    NASA Astrophysics Data System (ADS)

    Cao, Wenlun; Chen, Bei; He, Yuyao

    2013-03-01

    In this paper, the driver's hardware structure based on TMS320F28335 is introduced, the control software flow of host computer based on CAN bus is designed, the rule of CAN communication protocol is fulfilled and accordingly the hybrid programming is realized in the background of low speed and large sinusoid operation. This system can realize the CAN communication setting, download the PID parameters to DSP, operate at constant rotate speed and at given large sinusoid rotate speed. Meanwhile the dynamical monitoring and alarm are implemented. Finally the real-time display and storage of measured current, voltage and rotate speed are completed well.

  13. Multifactor-Driven Hierarchical Routing on Enterprise Service Bus

    NASA Astrophysics Data System (ADS)

    Mi, Xueqiang; Tang, Xinhuai; Yuan, Xiaozhou; Chen, Delai; Luo, Xiangfeng

    Message Routing is the foremost functionality on Enterprise Service Bus (ESB), but current ESB products don't provide an expected solution for it, especially in the aspects of runtime route change mechanism and service orchestration model. In order to solve the above drawbacks, this paper proposes a multifactor-driven hierarchical routing (MDHR) model. MDHR defines three layers for message routing on ESB. Message layer gives the original support for message delivery. Application layer can integration or encapsulate some legacy applications or un-standard services. Business layer introduces business model to supplies developers with a business rule configuration, which supports enterprise integration patterns and simplifies the service orchestration on ESB.

  14. DC Bus Regulation with a Flywheel Energy Storage System

    NASA Technical Reports Server (NTRS)

    Kenny, Barbara H.; Kascak, Peter E.

    2003-01-01

    This paper describes the DC bus regulation control algorithm for the NASA flywheel energy storage system during charge, charge reduction and discharge modes of operation. The algorithm was experimentally verified with results given in a previous paper. This paper presents the necessary models for simulation with detailed block diagrams of the controller algorithm. It is shown that the flywheel system and the controller can be modeled in three levels of detail depending on the type of analysis required. The three models are explained and then compared using simulation results.

  15. BC Transit Fuel Cell Bus Project Evaluation Results: Second Report

    SciTech Connect

    Eudy, L.; Post, M.

    2014-09-01

    Second report evaluating a fuel cell electric bus (FCEB) demonstration led by British Columbia Transit (BC Transit) in Whistler, Canada. BC Transit is collaborating with the California Air Resources Board and the U.S. Department of Energy's National Renewable Energy Laboratory to evaluate the buses in revenue service. NREL published its first report on the demonstration in February 2014. This report is an update to the previous report; it covers 3 full years of revenue service data on the buses from April 2011 through March 2014 and focuses on the final experiences and lessons learned.

  16. Development of a composite (K1100/CE) satellite bus structure

    SciTech Connect

    Hoffman, C.N.; Snyder, B.A.; Dean, M.W.

    1996-12-31

    This paper describes the use of high-performance composite materials (K1100 graphite fiber/cyanate ester matrix [Gr/CE]) for the structural design of a full-capability small satellite built for the Navy Geosat Follow-On (GFO) Program. A challenging combination of mission requirements and program budget constraints led to the production of an advanced technology, multifunctional composite satellite bus. The process started with top-level requirements to derive structural performance, then proceeded through material selection, detail design, and procurement. It culminated in a successful test program.

  17. A further study of air pollution in diesel bus garages.

    PubMed Central

    Waller, R E; Hampton, L; Lawther, P J

    1985-01-01

    The concentrations of smoke, polycyclic aromatic hydrocarbons (PAHs), and some gaseous air pollutants have been measured in two London Transport diesel bus garages and compared with observations made in the same garages over 20 years earlier. The main feature of the results was a large reduction in the background concentrations of smoke and polycyclic aromatic hydrocarbons from sources such as coal fires, attributable to the implementation of the Clean Air Act. Contributions from the buses to the benzo(a) pyrene content of the air inside the garages were of the same magnitude as before, being small in relation to former coal smoke contributions. PMID:4074654

  18. Common Spacecraft Bus for Earth Science Decadal Survey Missions

    NASA Astrophysics Data System (ADS)

    Cook, T.; Klaus, K.; Elsperman, M. S.

    2010-12-01

    Our study assessed the overall technical and programmatic viability of a Common Spacecraft Bus (CSB) approach that could satify the requirements of multiple Earth Science Decadal Mission programs resulting in cost and schedule savings over individual programs. Our approach developed a Common Payload Interface (CPIF) concept based on assessment of TIER I mission requirements to enable flexibility to the payloads while maintaining maximum commonality in the bus design. Satellite missions in Tier 1 of the Decadal Survey are missions with a launch period beginning in 2014. Four missions are planned and will measure climate change by examining solar and earth radiation, soil moisture and freeze/thaw cycles, ice sheet height differences, surface and ice sheet deformation from natural hazards, and vegetation structure (SMAP, ICESat-2, CLARREO, and DESDynI). Our study goals and objectives were: Develop a Common Spacecraft Bus (CSB) that incorporates the defined CPIF that can be configured to meet the individual Tier I mission specific requirements with minimal impacts or changes; Develop a efficient Assembly, Integration and Test (AI&T) flow and program schedule that can accommodate multiple Observatory level spacecraft processing and provide the flexibility to respond to program changes and other schedule perturbations; Develop a ROM cost for the CSB program approach, based on the reference design and schedules; Evaluate the CSB capability to host payloads of opportunity on the Tier I spacecraft; Evaluate the CSB capability to host the Tier II missions and what changes are required from the Tier I CSB We concluded: CSB approach for Tier I missions is feasible with very good synergy; Program Execution and AI&T approaches can be defined to take maximum advantage of CSB program approach and meet required launch readiness dates; ROM cost analysis indicates that a CSB approach is viable and offers substantial savings over separate procurements The Common Spacecraft Bus Architecture has flexibility, resources and capabilities to support beyond the Tier I Missions. There is additional CSB capability that could accommodate Payloads of Opportunity (PLO’s) on the Tier I missions - Complex Tier I operational, pointing, and field of view constraints indicate that PLO’s will need to be mostly passive and have limited additional constraints - Need to be cautious that PLO modifications for individual missions do not move away from the CSB approach; The CSB architecture has the capability to support two of the five Tier II missions; The CSB can be adapted to other LEO missions besides the Earth Science TIER I and II missions (space weather, helio/astrophysics, surveillance, etc.)

  19. Performance measurements of single server fuzzy queues with unreliable server using left and right method

    NASA Astrophysics Data System (ADS)

    Mueen, Zeina; Ramli, Razamin; Zaibidi, Nerda Zura

    2015-12-01

    There are a number of real life systems that can be described as a queuing system, and this paper presents a queuing system model applied in a manufacturing system example. The queuing model considered is depicted in a fuzzy environment with retrial queues and unreliable server. The stability condition state of this model is investigated and the performance measurement is obtained by adopting the left and right method. The new approach adopted in this study merges the existing α-cut interval and nonlinear programming techniques and a numerical example was considered to explain the methodology of this technique. From the numerical example, the flexibility of the method was shown graphically showing the exact real mean value of customers in the system and also the expected waiting times.

  20. A Closed Network Queue Model of Underground Coal Mining Production, Failure, and Repair

    NASA Technical Reports Server (NTRS)

    Lohman, G. M.

    1978-01-01

    Underground coal mining system production, failures, and repair cycles were mathematically modeled as a closed network of two queues in series. The model was designed to better understand the technological constraints on availability of current underground mining systems, and to develop guidelines for estimating the availability of advanced mining systems and their associated needs for spares as well as production and maintenance personnel. It was found that: mine performance is theoretically limited by the maintainability ratio, significant gains in availability appear possible by means of small improvements in the time between failures the number of crews and sections should be properly balanced for any given maintainability ratio, and main haulage systems closest to the mine mouth require the most attention to reliability.

  1. Modeling and Control of Airport Queueing Dynamics under Severe Flow Restrictions

    NASA Technical Reports Server (NTRS)

    Carr, Francis; Evans, Antony; Clarke, John-Paul; Deron, Eric

    2003-01-01

    Based on field observations and interviews with controllers at BOS and EWR, we identify the closure of local departure fixes as the most severe class of airport departure restrictions. A set of simple queueing dynamics and traffic rules are developed to model departure traffic under such restrictions. The validity of the proposed model is tested via Monte Carlo simulation against 10 hours of actual operations data collected during a case-study at EWR on June 29,2000. In general, the model successfully reproduces the aggregate departure congestion. An analysis of the average error over 40 simulation runs indicates that flow-rate restrictions also significantly impact departure traffic; work is underway to capture these effects. Several applications and what-if scenarios are discussed for future evaluation using the calibrated model.

  2. Reproductive queue without overt conflict in the primitively eusocial wasp Ropalidia marginata

    PubMed Central

    Bang, Alok; Gadagkar, Raghavendra

    2012-01-01

    Colonies of the primitively eusocial wasp Ropalidia marginata consist of a single egg layer (queen) and a number of non–egg-laying workers. Although the queen is a docile individual, not at the top of the behavioral dominance hierarchy of the colony, she maintains complete reproductive monopoly. If the queen is lost or removed, one and only one of the workers [potential queen (PQ)] becomes hyperaggressive and will become the next queen of the colony. The PQ is almost never challenged because she first becomes hyperaggressive and then gradually loses her aggression, develops her ovaries, and starts laying eggs. Although we are unable to identify the PQ when the queen is present, she appears to be a “cryptic heir designate.” Here, we show that there is not just one heir designate but a long reproductive queue and that PQs take over the role of egg-laying, successively, without overt conflict, as the queen or previous PQs are removed. The dominance rank of an individual is not a significant predictor of its position in the succession hierarchy. The age of an individual is a significant predictor, but it is not a perfect predictor because PQs often bypass older individuals to become successors. We suggest that such a predesignated reproductive queue that is implemented without overt conflict is adaptive in the tropics, where conspecific usurpers from outside the colony, which can take advantage of the anarchy prevailing in a queenless colony and invade it, are likely to be present throughout the year. PMID:22908278

  3. Dual Wavelength Lasers

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.

    2010-01-01

    Dual wavelength lasers are discussed, covering fundamental aspects on the spectroscopy and laser dynamics of these systems. Results on Tm:Ho:Er:YAG dual wavelength laser action (Ho at 2.1 m and Er at 2.9 m) as well as Nd:YAG (1.06 and 1.3 m) are presented as examples of such dual wavelength systems. Dual wavelength lasers are not common, but there are criteria that govern their behavior. Based on experimental studies demonstrating simultaneous dual wavelength lasing, some general conclusions regarding the successful operation of multi-wavelength lasers can be made.

  4. A programmable systolic trigger processor for FERA-bus data

    NASA Astrophysics Data System (ADS)

    Appelquist, G.; Hovander, B.; Sellden, B.; Bohm, C.

    1992-09-01

    A generic CAMAC based trigger processor module for fast processing of large amounts of Analog to Digital Converter (ADC) data was designed. This module was realized using complex programmable gate arrays. The gate arrays were connected to memories and multipliers in such a way that different gate array configurations can cover a wide range of module applications. Using this module, it is possible to construct complex trigger processors. The module uses both the fast ECL FERA bus and the CAMAC bus for inputs and outputs. The latter is used for set up and control but may also be used for data output. Large numbers of ADC's can be served by a hierarchical arrangement of trigger processor modules which process ADC data with pipeline arithmetics and produce the final result at the apex of the pyramid. The trigger decision is transmitted to the data acquisition system via a logic signal while numeric results may be extracted by the CAMAC controller. The trigger processor was developed for the proposed neutral particle search. It was designed to serve as a second level trigger processor. It was required to correct all ADC raw data for efficiency and pedestal, calculate the total calorimeter energy, obtain the optimal time of flight data, and calculate the particle mass. A suitable mass cut would then deliver the trigger decision.

  5. A programmable systolic trigger processor for FERA bus data

    NASA Astrophysics Data System (ADS)

    Appelquist, G.; Hovander, B.; Selldén, B.; Bohm, C.

    1993-04-01

    A generic CAMAC based trigger processor module for fast processing of large amounts of ADC data, has been designed. This module has been realised using complex programmable gate arrays (LCAs from XILINX). The gate arrays have been connected to memories and multipliers in such a way that different gate array configurations can cover a wide range of module applications. Using this module, it is possible to construct complex trigger processors. The module uses both the fast ECL FERA bus and the CAMAC bus for inputs and outputs. The latter, however, is primarily used for setup and control but may also be used for data output. Large numbers of ADCs can be served by a hierarchical arrangement of trigger processor modules, processing ADC data with pipe-line arithmetics producing the final result at the apex of the pyramid. The trigger decision will be transmitted to the data acquisition system via a logic signal while numeric results may be extracted by the CAMAC controller. The trigger processor was originally developed for the proposed neutral particle search experiment at CERN, NUMASS. There it was designed to serve as a second level trigger processor. It was required to correct all ADC raw data for efficiency and pedestal, calculate the total calorimeter energy, obtain the optimal time of flight data and calculate the particle mass. A suitable mass-cut would then deliver the trigger decision. More complex triggers were also considered.

  6. The universal serial bus endoscope: design and initial clinical experience.

    PubMed

    Hernandez-Zendejas, Gregorio; Dobke, Marek K; Guerrerosantos, Jose

    2004-01-01

    Endoscopic forehead lift is a well-established procedure in aesthetic plastic surgery. Many agree that currently available video-endoscopic equipment is bulky, multipieced and sometimes cumbersome in the operating theater. A novel system, the Universal Serial Bus Endoscope (USBE) was designed to simplify and reduce the number of necessary equipment pieces in the endoscopic setup. The USBE is attached by a single cable to a Universal Serial Bus (USB) port of a laptop computer. A built-in miniaturized cold light source provides illumination. A built-in digital camera chip enables procedure recording. The real-time images and movies obtained with USBE are displayed on the computer's screen and recorded on the laptop's hard disk drive. In this study, 25 patients underwent endoscopic browlift using the USBE system to test its clinical usefulness, all with good results and without complications or need for revision. The USBE was found to be reliable and easier to use than current video-endoscope equipment. The operative time needed to complete the procedure by the authors was reduced approximately 50%. The design and main technical characteristics of the USBE are presented. PMID:15383889

  7. A Conceptual Design for a Reliable Optical Bus (ROBUS)

    NASA Technical Reports Server (NTRS)

    Miner, Paul S.; Malekpour, Mahyar; Torres, Wilfredo

    2002-01-01

    The Scalable Processor-Independent Design for Electromagnetic Resilience (SPIDER) is a new family of fault-tolerant architectures under development at NASA Langley Research Center (LaRC). The SPIDER is a general-purpose computational platform suitable for use in ultra-reliable embedded control applications. The design scales from a small configuration supporting a single aircraft function to a large distributed configuration capable of supporting several functions simultaneously. SPIDER consists of a collection of simplex processing elements communicating via a Reliable Optical Bus (ROBUS). The ROBUS is an ultra-reliable, time-division multiple access broadcast bus with strictly enforced write access (no babbling idiots) providing basic fault-tolerant services using formally verified fault-tolerance protocols including Interactive Consistency (Byzantine Agreement), Internal Clock Synchronization, and Distributed Diagnosis. The conceptual design of the ROBUS is presented in this paper including requirements, topology, protocols, and the block-level design. Verification activities, including the use of formal methods, are also discussed.

  8. Building distributed rule-based systems using the AI Bus

    NASA Technical Reports Server (NTRS)

    Schultz, Roger D.; Stobie, Iain C.

    1990-01-01

    The AI Bus software architecture was designed to support the construction of large-scale, production-quality applications in areas of high technology flux, running heterogeneous distributed environments, utilizing a mix of knowledge-based and conventional components. These goals led to its current development as a layered, object-oriented library for cooperative systems. This paper describes the concepts and design of the AI Bus and its implementation status as a library of reusable and customizable objects, structured by layers from operating system interfaces up to high-level knowledge-based agents. Each agent is a semi-autonomous process with specialized expertise, and consists of a number of knowledge sources (a knowledge base and inference engine). Inter-agent communication mechanisms are based on blackboards and Actors-style acquaintances. As a conservative first implementation, we used C++ on top of Unix, and wrapped an embedded Clips with methods for the knowledge source class. This involved designing standard protocols for communication and functions which use these protocols in rules. Embedding several CLIPS objects within a single process was an unexpected problem because of global variables, whose solution involved constructing and recompiling a C++ version of CLIPS. We are currently working on a more radical approach to incorporating CLIPS, by separating out its pattern matcher, rule and fact representations and other components as true object oriented modules.

  9. Through Rain, Sleet, Ice, and Snow, the Walking School Bus Still Must Go!

    ERIC Educational Resources Information Center

    Paquette, Kelli R.

    2007-01-01

    In this article, the author describes the walking school bus--a physically active and safe method in which young learners can travel to and from school while accompanied by adult volunteers. The walking school bus provides a safe and healthy way for elementary-age children to travel to and from school. Many families who live within walking…

  10. A Summary of Selected Nationwide School Bus Crash Statistics in 1989. Technical Report.

    ERIC Educational Resources Information Center

    National Highway Traffic Safety Administration (DOT), Washington, DC.

    This document provides a summary of selected school bus crash statistics for 1989. Information was obtained from the following data sources: the Fatal Accident Reporting System (FARS), the General Estimates System (GES), and the School Bus Fleet Annual Fact Book. The data are organized into four sections: (1) a summary of national and selected…

  11. 75 FR 2583 - Over-the-Road Bus Accessibility Program Grants

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-15

    ... Federal Transit Administration Over-the-Road Bus Accessibility Program Grants AGENCY: Federal Transit...) announces the availability of funds in Fiscal Year (FY) 2009 for the Over-the-Road Bus (OTRB) Accessibility... OTRB Accessibility Program makes funds available to private operators of over-the-road buses to...

  12. 77 FR 71865 - Over-the-Road Bus Accessibility Grant Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-04

    ... Federal Transit Administration Over-the-Road Bus Accessibility Grant Program AGENCY: Federal Transit... Fiscal Year (FY) 2012 appropriations for the Over-the-Road Bus (OTRB) Accessibility Program, authorized... Accessibility Program makes funds available to private operators of over-the-road buses to help finance...

  13. 77 FR 5295 - Over-the-Road Bus Accessibility Program Announcement of Project Selections

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-02

    ... TRANSPORTATION Federal Transit Administration Over-the-Road Bus Accessibility Program Announcement of Project... Fiscal Year (FY) 2011 appropriations for the Over-the-Road Bus (OTRB) Accessibility Program, authorized... Accessibility Program makes funds available to private operators of over-the-road buses to help finance...

  14. 75 FR 20034 - Over-the-Road Bus Accessibility Program Grants: Corrections

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-16

    ... 215 (73 FR 47046, Aug. 13, 2008). On October 1, 2008, DOL began using a revised special warranty for... Federal Transit Administration Over-the-Road Bus Accessibility Program Grants: Corrections AGENCY: Federal..., 2010 Federal Transit Administration (FTA) Notice titled ``Over-the-Road Bus Accessibility...

  15. 77 FR 25529 - Over-the-Road Bus Accessibility Program Grants

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-30

    ... this authorization, the DOL amended its implementing regulations at 29 CFR part 215 (73 FR 47046, Aug... TRANSPORTATION Federal Transit Administration Over-the-Road Bus Accessibility Program Grants AGENCY: Federal... availability of funds in Fiscal Year (FY) 2012 for the Over-the-Road Bus Accessibility (OTRB)...

  16. Drive Cycle Analysis, Measurement of Emissions and Fuel Consumption of a PHEV School Bus: Preprint

    SciTech Connect

    Barnitt, R.; Gonder, J.

    2011-04-01

    The National Renewable Energy Laboratory (NREL) collected and analyzed real-world school bus drive cycle data and selected similar standard drive cycles for testing on a chassis dynamometer. NREL tested a first-generation plug-in hybrid electric vehicle (PHEV) school bus equipped with a 6.4L engine and an Enova PHEV drive system comprising a 25-kW/80 kW (continuous/peak) motor and a 370-volt lithium ion battery pack. A Bluebird 7.2L conventional school bus was also tested. Both vehicles were tested over three different drive cycles to capture a range of driving activity. PHEV fuel savings in charge-depleting (CD) mode ranged from slightly more than 30% to a little over 50%. However, the larger fuel savings lasted over a shorter driving distance, as the fully charged PHEV school bus would initially operate in CD mode for some distance, then in a transitional mode, and finally in a charge-sustaining (CS) mode for continued driving. The test results indicate that a PHEV school bus can achieve significant fuel savings during CD operation relative to a conventional bus. In CS mode, the tested bus showed small fuel savings and somewhat higher nitrogen oxide (NOx) emissions than the baseline comparison bus.

  17. 49 CFR 571.221 - Standard No. 221; School bus body joint strength.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...) NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION FEDERAL MOTOR VEHICLE SAFETY STANDARDS Federal Motor Vehicle Safety Standards § 571.221 Standard No. 221; School bus body joint strength... plane tangent to the rear interior wall of the bus at the vehicle centerline. Serviceable...

  18. Spaceflight qualification of the SEDS MIL-STD-1773 fiber optic data bus

    NASA Astrophysics Data System (ADS)

    Flanegan, Mark C.

    1993-09-01

    The small explorer (SMEX) project at Goddard Space Flight Center (GSFC) launched the first spaceflight implementation of the MIL-STD-1773 fiber optic data bus on the Solar Anomalous Magnetospheric Particle Explorer (SAMPEX) in July of 1992. The Small Explorer Data System (SEDS), of which the MIL-STD-1773 data bus is a part, has been successful. The MIL-STD-1773 bus is the implementation of the MIL-STD-1553 protocol using fiber optics. Advantages of the fiber optic bus over the electrical bus include lower power, lower weight, and immunity from EMI/RFI. It does not radiate electrical or magnetic fields. It is a nonconductor so it cannot conduct electrical noise into or from a subsystem. This is particularly advantageous on a spacecraft with very sensitive instruments which are often susceptible to electrical interference. Although the MIL-STD-1773 bus is a 1 Mbps bus like the MIL-STD-1553 bus, the fiber optics also provide a path to the much higher rate systems required in upcoming NASA missions.

  19. NREL's Hydrogen-Powered Bus Serves as Showcase for Advanced Vehicle Technologies (AVT) (Brochure)

    SciTech Connect

    Not Available

    2010-08-01

    Brochure describes the hydrogen-powered internal combustion engine (H2ICE) shuttle bus at NREL. The U.S. Department of Energy (DOE) is funding the lease of the bus from Ford to demonstrate market-ready advanced technology vehicles to visitors at NREL.

  20. This Could Save Your Child's Life. A School Bus Handrail Handbook.

    ERIC Educational Resources Information Center

    National Highway Traffic Safety Administration (DOT), Washington, DC.

    School-bus handrails have had the same basic design for more than 30 years. However, students' recent propensity to wear oversized and baggy clothing increases the likelihood that clothing or accessories may become snagged on bus handrails. Children across the United States have been injured or killed when their clothing or accessories caught in…

  1. 49 CFR 571.221 - Standard No. 221; School bus body joint strength.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 6 2013-10-01 2013-10-01 false Standard No. 221; School bus body joint strength... STANDARDS Federal Motor Vehicle Safety Standards § 571.221 Standard No. 221; School bus body joint strength. S1. Scope. This standard establishes requirements for the strength of the body panel joints in...

  2. 49 CFR 571.221 - Standard No. 221; School bus body joint strength.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 6 2012-10-01 2012-10-01 false Standard No. 221; School bus body joint strength... STANDARDS Federal Motor Vehicle Safety Standards § 571.221 Standard No. 221; School bus body joint strength. S1. Scope. This standard establishes requirements for the strength of the body panel joints in...

  3. 49 CFR 571.221 - Standard No. 221, School bus body joint strength.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 6 2013-10-01 2013-10-01 false Standard No. 221, School bus body joint strength. 571.221 Section 571.221 Transportation Other Regulations Relating to Transportation (Continued... STANDARDS Federal Motor Vehicle Safety Standards § 571.221 Standard No. 221, School bus body joint...

  4. 49 CFR 571.221 - Standard No. 221, School bus body joint strength.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 6 2012-10-01 2012-10-01 false Standard No. 221, School bus body joint strength. 571.221 Section 571.221 Transportation Other Regulations Relating to Transportation (Continued... STANDARDS Federal Motor Vehicle Safety Standards § 571.221 Standard No. 221, School bus body joint...

  5. 49 CFR 571.221 - Standard No. 221, School bus body joint strength.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 6 2014-10-01 2014-10-01 false Standard No. 221, School bus body joint strength. 571.221 Section 571.221 Transportation Other Regulations Relating to Transportation (Continued... STANDARDS Federal Motor Vehicle Safety Standards § 571.221 Standard No. 221, School bus body joint...

  6. 49 CFR 571.221 - Standard No. 221, School bus body joint strength.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 6 2011-10-01 2011-10-01 false Standard No. 221, School bus body joint strength. 571.221 Section 571.221 Transportation Other Regulations Relating to Transportation (Continued... STANDARDS Federal Motor Vehicle Safety Standards § 571.221 Standard No. 221, School bus body joint...

  7. Evoking Emotions and Unpacking Layered Histories through Young Children's Illustrations of Racial Bus Segregation

    ERIC Educational Resources Information Center

    Kuby, Candace R.

    2013-01-01

    Drawing on theories of multi-modality and critical visual literacy, this article focuses on images that five-and six year-olds painted in a class-made book, Voice on the Bus, about racial segregation. The article discusses how children used illustrations to convey their understandings of Rosa Parks' bus arrest in Alabama. A post-structural view…

  8. 49 CFR 571.221 - Standard No. 221; School bus body joint strength.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 6 2010-10-01 2010-10-01 false Standard No. 221; School bus body joint strength... STANDARDS Federal Motor Vehicle Safety Standards § 571.221 Standard No. 221; School bus body joint strength. S1. Scope. This standard establishes requirements for the strength of the body panel joints in...

  9. 49 CFR 571.221 - Standard No. 221, School bus body joint strength.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 6 2010-10-01 2010-10-01 false Standard No. 221, School bus body joint strength. 571.221 Section 571.221 Transportation Other Regulations Relating to Transportation (Continued... STANDARDS Federal Motor Vehicle Safety Standards § 571.221 Standard No. 221, School bus body joint...

  10. Contribution analysis of bus pass-by noise based on dynamic transfer path method

    NASA Astrophysics Data System (ADS)

    Liu, Haitao; Zheng, Sifa; Hao, Peng; Lian, Xiaomin

    2011-10-01

    Bus pass-by noise has become one of the main noise sources which seriously disturb the mental and physical health of urban residents. The key of reducing bus noise is to identify major noise source. In this paper the dynamic transfer characteristic model in the process of bus acceleration is established, which can quantitatively describe the relationship between the sound source or vibration source of the vehicle and the response points outside the vehicle; also a test method has been designed, which can quickly and easily identify the contribution of the bus pass-by noise. Experimental results show that the dynamic transfer characteristic model can identify the main noise source and their contribution during the acceleration, which has significance for the bus noise reduction.

  11. A contention-based bus-control scheme for multiprocessor systems

    NASA Technical Reports Server (NTRS)

    Juang, Jie-Yong; Wah, Benjamin W.

    1991-01-01

    The authors study contention-based bus-control schemes for scheduling processors in using a bit-parallel shared bus. The protocol is designed under the requirements that each processor exhibit a random access behavior, that there be no centralized bus control in the system, and that access be granted in real time. The proposed scheme is based on splitting algorithms used in conventional contention-resolution schemes, and utilizes two-state information obtained from collision detection. Two versions of the bus-control scheme are studied. The static one resolves contentions of N requesting processors in an average of O(logW/2N) iterations, where W is the number of bits in the bit-parallel bus. An adaptive version resolves contentions in an average time that is independent of N.

  12. SunLine Transit Agency Advanced Technology Fuel Cell Bus Evaluation: Second Results Report and Appendices

    SciTech Connect

    Eudy, L.; Chandler, K.

    2011-10-01

    This report describes operations at SunLine Transit Agency for their newest prototype fuel cell bus and five compressed natural gas (CNG) buses. In May 2010, SunLine began operating its sixth-generation hydrogen fueled bus, an Advanced Technology (AT) fuel cell bus that incorporates the latest design improvements to reduce weight and increase reliability and performance. The agency is collaborating with the U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) to evaluate the bus in revenue service. This is the second results report for the AT fuel cell bus since it was placed in service, and it focuses on the newest data analysis and lessons learned since the previous report. The appendices, referenced in the main report, provide the full background for the evaluation. They will be updated as new information is collected but will contain the original background material from the first report.

  13. 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.

  14. 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.

  15. Surgically revascularized dual LAD.

    PubMed

    Yavuz, Turhan; Nazli, Cem; Ocal, Ahmet; Ibrisim, Erdogan; Kutsal, Ali

    2004-02-01

    Dual left anterior descending artery (or dual anterior interventricular artery, LAD) is a rare coronary artery anomaly. Dual but normally originated LAD has been usually reported to have no clinical significance. In this case report, we present a case of 75 year old male with anginal symptoms in whom coronary arteriography showed normally originated dual LAD with two branches of almost equal caliber. The course of both branches were supplying the usual territory of LAD and both of the branches had significant proximal stenosis. The patient underwent a coronary artery bypass grafting operation and both branches were grafted. This normally originated dual LAD case may be considered to be interesting, because dual LAD branches were symmetrically involved with the atherosclerotic process in their proximal segments. In addition, this condition was demonstrated intraoperatively and the two branches were revascularized with bypass grafting. PMID:15055824

  16. Finding the biased-shortest path with minimal congestion in networks via linear-prediction of queue length

    NASA Astrophysics Data System (ADS)

    Shen, Yi; Ren, Gang; Liu, Yang

    2016-06-01

    In this paper, we propose a biased-shortest path method with minimal congestion. In the method, we use linear-prediction to estimate the queue length of nodes, and propose a dynamic accepting probability function for nodes to decide whether accept or reject the incoming packets. The dynamic accepting probability function is based on the idea of homogeneous network flow and is developed to enable nodes to coordinate their queue length to avoid congestion. A path strategy incorporated with the linear-prediction of the queue length and the dynamic accepting probability function of nodes is designed to allow packets to be automatically delivered on un-congested paths with short traveling time. Our method has the advantage of low computation cost because the optimal paths are dynamically self-organized by nodes in the delivering process of packets with local traffic information. We compare our method with the existing methods such as the efficient path method (EPS) and the optimal path method (OPS) on the BA scale-free networks and a real example. The numerical computations show that our method performs best for low network load and has minimum run time due to its low computational cost and local routing scheme.

  17. 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. PMID:22319385

  18. Novel low cost standardized Nano-Satellite structure bus for LEO missions

    NASA Astrophysics Data System (ADS)

    Anubhav, T.; Sarwesh, P.; Narayan, V.; Varma, P. A.; Prasad, R. A.; Loganathan, M.; Rao, D. N.; Sriram, S.; Venkatesh, M.

    This paper focuses on SRMSAT STRUCTURE BUS which is a standardized Nano-Satellite structure bus. It provides a standard platform for a wide variety of missions in LEO and can be realized in a very short developmental period. The bus was designed and developed for SRMSAT, the SRM University (Sri Ramaswamy Memorial University) student Nano-Satellite, by the undergraduate students and faculty of SRM University in collaboration with Indian Space Research Organization (ISRO). The bus can support payloads up to a mass of 20kg. SRMSAT STRUCTURE BUS has a mass of around 6 kg and dimensions 280mm × 280mm × 280mm with an available volume of 11000 cc. Vibration Testing of the bus has been performed upto 6.7 gRMS. This makes the satellite capable of being launched by any launch vehicle in the world. An innovative PCB mounting design has been introduced in this structure bus which facilitates mounting of a maximum 7 PCB trays independently, each tray capable of holding a 250 mm2 PCB. Structural analysis of SRMSAT STRUCTURE BUS was done using NX Nastran. The boundary conditions for each analysis were defined based on the loading conditions as specified by the launcher, PSLV (Polar Satellite Launch Vehicle). Optimization of each individual component was performed by maintaining a minimum threshold between the local frequencies of the component and global frequencies of the entire satellite. Static, Modal, Harmonic and Random Vibration analysis of the structure bus was performed. This paper also describes the methodology followed in the static and dynamic analysis of the structure bus to finalize the design. The results have been tested and validated at ISRO Satellite Centre, Bangalore with around 90% accuracy and the structure has been certified as a standard structure bus for Nano-satellite missions. In terms of expandability, this structure bus is capable of accommodating deployable solar panels. Also, the payload mounting is not only restricted to th- bottom deck but can also be done in the top or side decks as required for specific missions. This enhances the scope of small satellites which has not been possible with previous satellites of the same size. SRMSAT which utilized this bus was launched on-board PSLV C-18 on 12th October 2011 with the scientific objective of measuring greenhouse gases, namely CO2 and H2O.

  19. A fast data-bus to buffer-memory interface

    NASA Astrophysics Data System (ADS)

    Vander Molen, A.; Maier, M. R.; Robertson, M.; Westfall, G. D.

    1991-09-01

    A fast, economical VME based interface between fast data buses and high speed buffer memories has been built. This module in addition to handling the hand-shaking lines, supplies a gate, a busy signal, and a clear signal at the end of data transfer. A header word with programmable contents is inserted at the beginning of each event giving a discernable event boundary. This device, dubbed the FERA Faucet Maier (FFM), has been applied to the LeCroy ECLine bus coupled to a Creative Electronics Solution 8170 High Speed Memory. It will transfer data at rates up to 10 Mbytes/s from the LeCroy FERAs to the VME based memory.

  20. Modeling a bus through a sequence of traffic lights

    NASA Astrophysics Data System (ADS)

    Villalobos, Jorge; Muñoz, Víctor; Rogan, José; Zarama, Roberto; Penagos, Juan Felipe; Toledo, Benjamín; Valdivia, Juan Alejandro

    2015-07-01

    We propose a model of a bus traveling through a sequence of traffic lights, which is required to stop between the traffic signals to pick up passengers. A two dimensional model, of velocity and traveled time at each traffic light, is constructed, which shows non-trivial and chaotic behaviors for realistic city traffic parameters. We restrict the parameter values where these non-trivial and chaotic behaviors occur, by following analytically and numerically the fixed points and period 2 orbits. We define conditions where chaos may arise by determining regions in parameter space where the maximum Lyapunov exponent is positive. Chaos seems to occur as long as the ratio of the braking and accelerating capacities are greater than about ˜3.

  1. Low Bus Voltage Hydrazine Arcjet System for Geostationary Satellites

    NASA Astrophysics Data System (ADS)

    Zube, Dieter M.; Fye, Dan

    1998-07-01

    The capabilities of arcjet propulsion systems were recently extended to accommodate operation on the NASDA Data Relay Test Satellite (DRTS) providing a power bus voltage between 31 and 51.5 VDC. This paper summarizes the newly attained qualification status of the MR 512 arcjet system demonstrating the flexibility of the current design. A redesign of the Power Processing Unit (PPU) became necessary as well as a delta-qualification of the thruster to validate spacecraft integration and to provide compliance with the DRTS satellite environmental requirements. Two types of thrusters with different thrust levels were made available to meet mission requirements. The delta-qualification included a pyro-shock test, vibration tests to a higher level than previously tested, and performance mapping beyond the original range. Included in the paper is an assessment of the PPU performance characteristics as well as the discussion of the system operation and system telemetry.

  2. Baseline Testing of the Hybrid Electric Transit Bus

    NASA Technical Reports Server (NTRS)

    Brown, Jeffrey C.; Eichenberg, Dennis J.; Thompson, William K.

    1999-01-01

    A government, industry and academic cooperative has developed a Hybrid Electric Transit Bus (HETB). Goals of the program include doubling the fuel economy of city transit buses currently in service, and reducing emissions to one-tenth of EPA standards. Unique aspects of the vehicle's power system include the use of ultra-capacitors for the energy storage system and the planned use of a natural gas fueled turbogenerator, to be developed from a small jet engine. At over 17000 kg gross weight, this is the largest vehicle to use ultra-capacitor energy storage. A description of the HETB, the results of performance testing, and future vehicle development plans are the subject of this report.

  3. Modeling a bus through a sequence of traffic lights.

    PubMed

    Villalobos, Jorge; Muñoz, Víctor; Rogan, José; Zarama, Roberto; Penagos, Juan Felipe; Toledo, Benjamín; Valdivia, Juan Alejandro

    2015-07-01

    We propose a model of a bus traveling through a sequence of traffic lights, which is required to stop between the traffic signals to pick up passengers. A two dimensional model, of velocity and traveled time at each traffic light, is constructed, which shows non-trivial and chaotic behaviors for realistic city traffic parameters. We restrict the parameter values where these non-trivial and chaotic behaviors occur, by following analytically and numerically the fixed points and period 2 orbits. We define conditions where chaos may arise by determining regions in parameter space where the maximum Lyapunov exponent is positive. Chaos seems to occur as long as the ratio of the braking and accelerating capacities are greater than about ∼3. PMID:26232968

  4. [Bus drivers' biomechanical risk assessment in two different contexts].

    PubMed

    Baracco, A; Coggiola, M; Perrelli, F; Banchio, M; Martignone, S; Gullino, A; Romano, C

    2012-01-01

    The application of standardize methods for the biomechanical risk assessment in non-industrial cycled activity is not always possible. A typical case is the public transport sector, where workers complain of suffering for shoulder more than elbow and wrist pains. The Authors present the results of two studies involving two public transport companies and the risk of biomechanical overload of upper limbs for bus and tram drivers. The analysis has been made using three different approaches: focus groups; static analysis by using anthropometric manikins; work sampling technique by monitoring worker's activity and posture at each minute, for two hours and for each binomial vehicle-route, considering P5F e P95M drivers and assessing the perceived efforts thorough the Borg's CR10 Scale. The conclusive results show that the ergonomic analysis managed by multiple non-standardized techniques may reach consistent and repeatable results according to the epidemiological evidences. PMID:23405589

  5. 1D Runoff-runon stochastic model in the light of queueing theory : heterogeneity and connectivity

    NASA Astrophysics Data System (ADS)

    Harel, M.-A.; Mouche, E.; Ledoux, E.

    2012-04-01

    Runoff production on a hillslope during a rainfall event may be simplified as follows. Given a soil of constant infiltrability I, which is the maximum amount of water that the soil can infiltrate, and a constant rainfall intensity R, runoff is observed where R is greater than I. The infiltration rate equals the infiltrability when runoff is produced, R otherwise. When ponding time, topography, and overall spatial and temporal variations of physical parameters, such as R and I, are neglected, the runoff equation remains simple. In this study, we consider soils of spatially variable infiltrability. As runoff can re-infiltrate on down-slope areas of higher infiltrabilities (runon), the resulting process is highly non-linear. The stationary runoff equation is: Qn+1 = max(Qn + (R - In)*Δx , 0) where Qn is the runoff arriving on pixel n of size Δx [L2/T], R and In the rainfall intensity and infiltrability on that same pixel [L/T]. The non-linearity is due to the dependence of infiltration on R and Qn, that is runon. This re-infiltration process generates patterns of runoff along the slope, patterns that organise and connect to each other differently depending on the rainfall intensity and the nature of the soil heterogeneity. The runoff connectivity, assessed using the connectivity function of Allard (1993), affects greatly the dynamics of the runoff hillslope. Our aim is to assess, in a stochastic framework, the runoff organization on 1D slopes with random infiltrabilities (log-normal, exponential, bimodal and uniform distributions) by means of theoretical developments and numerical simulations. This means linking the nature of soil heterogeneity with the resulting runoff organisation. In term of connectivity, we investigate the relations between structural (infiltrability) and functional (runoff) connectivity. A theoretical framework based on the queueing theory is developed. We implement the idea of Jones et al. (2009), who remarked that the above formulation is identical to the waiting time equation in a single server queue. Thanks to this theory, it is possible to accurately describe some outputs of our numerical model, notably the runoff repartition over the slope for uncorrelated exponential infiltrability distributions. Alternative formulations for the connectivity function of Allard (which cannot be predicted theoretically to our knowledge) are discussed with regard to predictability, efficiency in computation and qualification of the "near-connectedness" state of the system.

  6. Indonesian commercial bus drum brake system temperature model

    NASA Astrophysics Data System (ADS)

    Wibowo, D. B.; Haryanto, I.; Laksono, N. P.

    2016-03-01

    Brake system is the most significant aspect of an automobile safety. It must be able to slow the vehicle, quickly intervening and reliable under varying conditions. Commercial bus in Indonesia, which often stops suddenly and has a high initial velocity, will raise the temperature of braking significantly. From the thermal analysis it is observed that for the bus with the vehicle laden mass of 15 tons and initial velocity of 80 km/h the temperature is increasing with time and reaches the highest temperature of 270.1 °C when stops on a flat road and reaches 311.2 °C on a declination road angle, ø, 20°. These temperatures exceeded evaporation temperature of brake oil DOT 3 and DOT 4. Besides that, the magnitude of the braking temperature also potentially lowers the friction coefficient of more than 30%. The brakes are pressed repeatedly and high-g decelerations also causes brake lining wear out quickly and must be replaced every 1 month as well as the emergence of a large thermal stress which can lead to thermal cracking or thermal fatigue crack. Brake fade phenomenon that could be the cause of many buses accident in Indonesia because of the failure of the braking function. The chances of accidents will be even greater when the brake is worn and not immediately replaced which could cause hot spots as rivets attached to the brake drum and brake oil is not changed for more than 2 years that could potentially lower the evaporation temperature because of the effect hygroscopic.

  7. A High Efficiency DC Bus Regulator/RPC for Spacecraft Applications

    NASA Technical Reports Server (NTRS)

    Birchenough, Arthur G.

    2003-01-01

    DC bus voltage regulation may be required in future high powered spacecraft due to the length of the busses or because they are not generated at precise voltage levels. In these cases the regulation range is often only a few percent increase or decrease, but conventional DC voltage regulators switch all the power passing through them, and this level of power switched determines the size and losses in the regulator. A recently developed concept used a low power DC-DC converter in series with the bs to raise or lower the bus voltage over a small range. This partial power processing technique combines the small size and power losses of the low power converter with the ability to regulate, (over a small range) a high power bus. The Series Connected Buck Boost Regulator (SCBBR) described herein provides bus regulation with an efficiency of 98%. The circuit also provides bus switching and overcurrent limiting functions of a Remote Power Controller (RPC). This paper described the circuit design and performance of a breadboard SCBBR configured as a bus voltage regulator providing plus of minus 40% voltage regulation range, bus switching, and overload limiting.

  8. Prevalence and factors associated with road traffic crash among bus drivers in Hanoi, Vietnam.

    PubMed

    La, Quang Ngoc; Lee, Andy H; Meuleners, Lynn B; Van Duong, Dat

    2013-01-01

    Bus provides a main mode of public transport in Vietnam, but the risk of road traffic crash for bus drivers is unknown. This retrospective study estimated the crash prevalence among bus drivers in Hanoi, Vietnam, and identified driver characteristics affecting their crashes. Information on bus crashes for the period 2006-2009 was collected by interviewing drivers from five bus companies in Hanoi using a structured questionnaire. Logistic regression analysis was performed to determine pertinent risk factors affecting the crash prevalence for bus drivers. Of the total 365 participants recruited, 73 drivers reported 76 crashes, giving an overall crash prevalence of 20%. Among the crashed group, three drivers (4%) were involved in two crashes during the past 3 years. Crashes mainly occurred on streets or local roads (81%). Migrant worker (adjusted odds ratio (OR) 4.26, 95% confidence interval (CI) 2.20-8.25) and insufficient income perceived (OR 2.60, 95% CI 1.37-4.93) were identified to be significantly associated with the crash risk. Further prospective and qualitative studies are needed to provide detailed crash characteristics as well as behaviour and perception of bus drivers, so that an effective intervention can be developed to improve road safety and to prevent traffic injury of these drivers. PMID:23190322

  9. COMPARISON OF PARALLEL AND SERIES HYBRID POWERTRAINS FOR TRANSIT BUS APPLICATION

    SciTech Connect

    Gao, Zhiming; Daw, C Stuart; Smith, David E; Jones, Perry T; LaClair, Tim J; Parks, II, James E

    2016-01-01

    The fuel economy and emissions of both conventional and hybrid buses equipped with emissions aftertreatment were evaluated via computational simulation for six representative city bus drive cycles. Both series and parallel configurations for the hybrid case were studied. The simulation results indicate that series hybrid buses have the greatest overall advantage in fuel economy. The series and parallel hybrid buses were predicted to produce similar CO and HC tailpipe emissions but were also predicted to have reduced NOx tailpipe emissions compared to the conventional bus in higher speed cycles. For the New York bus cycle (NYBC), which has the lowest average speed among the cycles evaluated, the series bus tailpipe emissions were somewhat higher than they were for the conventional bus, while the parallel hybrid bus had significantly lower tailpipe emissions. All three bus powertrains were found to require periodic active DPF regeneration to maintain PM control. Plug-in operation of series hybrid buses appears to offer significant fuel economy benefits and is easily employed due to the relatively large battery capacity that is typical of the series hybrid configuration.

  10. Weak Convergence and Fluid Limits in Optimal Time-to-Empty Queueing Control Problems

    SciTech Connect

    Day, Martin V.

    2011-12-15

    We consider a class of controlled queue length processes, in which the control allocates each server's effort among the several classes of customers requiring its service. Served customers are routed through the network according to (prescribed) routing probabilities. In the fluid rescaling, X{sup n}(t) = 1/nX(nt) , we consider the optimal control problem of minimizing the integral of an undiscounted positive running cost until the first time that X{sup n}=0. Our main result uses weak convergence ideas to show that the optimal value functions V{sup n} of the stochastic control problems for X{sup n}(t) converge (as n{yields}{infinity}) to the optimal value V of a control problem for the limiting fluid process. This requires certain equicontinuity and boundedness hypotheses on (V{sup n}). We observe that these are essentially the same hypotheses that would be needed for the Barles-Perthame approach in terms of semicontinuous viscosity solutions. Sufficient conditions for these equicontinuity and boundedness properties are briefly discussed.

  11. Network-of-queues approach to B-cell-receptor affinity discrimination

    NASA Astrophysics Data System (ADS)

    Felizzi, Federico; Comoglio, Federico

    2012-06-01

    The immune system is one of the most complex signal processing machineries in biology. The adaptive immune system, consisting of B and T lymphocytes, is activated in response to a large spectrum of pathogen antigens. B cells recognize and bind the antigen through B-cell receptors (BCRs) and this is fundamental for B-cell activation. However, the system response is dependent on BCR-antigen affinity values that span several orders of magnitude. Moreover, the ability of the BCR to discriminate between affinities at the high end (e.g., 109M-1-1010M-1) challenges the formulation of a mathematical model able to robustly separate these affinity-dependent responses. Queuing theory enables the analysis of many related processes, such as those resulting from the stochasticity of protein binding and unbinding events. Here we define a network of queues, consisting of BCR early signaling states and transition rates related to the propensity of molecular aggregates to form or disassemble. By considering the family of marginal distributions of BCRs in a given signaling state, we report a significant separation (measured as Jensen-Shannon divergence) that arises from a broad spectrum of antigen affinities.

  12. Traffic Regulation on Wireless 802.11 Networks Using Multiple Queue Technique

    NASA Astrophysics Data System (ADS)

    Dhanal, Radhika J.; Patil, G. A.

    2010-11-01

    WLAN technologies are becoming increasingly popular and are platform for many future applications. IEEE 802.11 Wireless LAN (WLAN) is an excellent solution for the broadband wireless networking. This paper presents a simple approach to enhance the performance of real time (RT) and non-real time (NRT) services over the 802.11 WLAN by using some special queues. This requires the system to first identify the type of service and then use the appropriate scheduling algorithm. The admission control algorithm is used first to determine the admission of particular station. Deficit round robin algorithm is used to set the priorities to RT and NRT packets in order to increase the QoS of WLAN. So we can combine both these algorithms by implementing them one after another. The proposed scheme can improve Voice/Data/Video services through simple software upgrades by reducing the delay, jitter and increasing the throughput. Through simulation, we show that the proposed scheme can give better QoS than existing schemes.

  13. Development of a high-temperature superconducting bus conductor with large current capacity

    NASA Astrophysics Data System (ADS)

    Wang, Yinshun; Zhang, Fenfyuan; Gao, Zhiyuan; Zhu, Zhiqin; Dai, Shaotao; Lin, Liangzhen; Xiao, Liye

    2009-05-01

    A high-temperature superconducting (HTS) bus conductor with a capacity of 20 kA and 5 m long has been constructed. The HTS bus was wound by hermetic stainless-steel-reinforced multifilamentary Bi2223/Ag tapes. Its structure is multilayer by clockwise and anticlockwise winding with different winding spiral pitch and angle based on a conventional uniform current approach. The joint technology between HTS tapes and terminations is developed in order to ensure that the resistances between them are as small as possible. Fundamental characteristics of the HTS bus conductor are obtained at the liquid nitrogen temperature of 77 K.

  14. Connecticut Transit (CTTRANSIT) Fuel Cell Transit Bus: Third Evaluation Report and Appendices

    SciTech Connect

    Chandler, K.; Eudy, L.

    2010-01-01

    This report describes operations at Connecticut Transit (CTTRANSIT) in Hartford for one prototype fuel cell bus and three new diesel buses operating from the same location. The prototype fuel cell bus was manufactured by Van Hool and ISE Corp. and features an electric hybrid drive system with a UTC Power PureMotion 120 Fuel Cell Power System and ZEBRA batteries for energy storage. The fuel cell bus started operation in April 2007, and evaluation results through October 2009 are provided in this report.

  15. Characterizing the range of children's air pollutant exposure during school bus commutes.

    PubMed

    Sabin, Lisa D; Behrentz, Eduardo; Winer, Arthur M; Jeong, Seong; Fitz, Dennis R; Pankratz, David V; Colome, Steven D; Fruin, Scott A

    2005-09-01

    Real-time and integrated measurements of gaseous and particulate pollutants were conducted inside five conventional diesel school buses, a diesel bus with a particulate trap, and a bus powered by compressed natural gas (CNG) to determine the range of children's exposures during school bus commutes and conditions leading to high exposures. Measurements were made during 24 morning and afternoon commutes on two Los Angeles Unified School District bus routes from South to West Los Angeles, with seven additional runs on a rural/suburban route, and three runs to test the effect of window position. For these commutes, the mean concentrations of diesel vehicle-related pollutants ranged from 0.9 to 19 microg/m(3) for black carbon, 23 to 400 ng/m(3) for particle-bound polycyclic aromatic hydrocarbon (PB-PAH), and 64 to 220 microg/m(3) for NO(2). Concentrations of benzene and formaldehyde ranged from 0.1 to 11 microg/m(3) and 0.3 to 5 microg/m(3), respectively. The highest real-time concentrations of black carbon, PB-PAH and NO(2) inside the buses were 52 microg/m(3), 2000 ng/m(3), and 370 microg/m(3), respectively. These pollutants were significantly higher inside conventional diesel buses compared to the CNG bus, although formaldehyde concentrations were higher inside the CNG bus. Mean black carbon, PB-PAH, benzene and formaldehyde concentrations were higher when the windows were closed, compared with partially open, in part, due to intrusion of the bus's own exhaust into the bus cabin, as demonstrated through the use of a tracer gas added to each bus's exhaust. These same pollutants tended to be higher on urban routes compared to the rural/suburban route, and substantially higher inside the bus cabins compared to ambient measurements. Mean concentrations of pollutants with substantial secondary formation, such as PM(2.5), showed smaller differences between open and closed window conditions and between bus routes. Type of bus, traffic congestion levels, and encounters with other diesel vehicles contributed to high exposure variability between runs. PMID:15592444

  16. Single Axis Attitude Control and DC Bus Regulation with Two Flywheels

    NASA Technical Reports Server (NTRS)

    Kascak, Peter E.; Jansen, Ralph H.; Kenny, Barbara; Dever, Timothy P.

    2002-01-01

    A computer simulation of a flywheel energy storage single axis attitude control system is described. The simulation models hardware which will be experimentally tested in the future. This hardware consists of two counter rotating flywheels mounted to an air table. The air table allows one axis of rotational motion. An inertia DC bus coordinator is set forth that allows the two control problems, bus regulation and attitude control, to be separated. Simulation results are presented with a previously derived flywheel bus regulator and a simple PID attitude controller.

  17. Dual Enrollment Academy Programs

    ERIC Educational Resources Information Center

    Gonzalez, Nicolas; Chavez, Guadalupe

    2009-01-01

    Dual Enrollment Engineering (DEEA) and Medical Science (DEMSA) Academies are two-year dual enrollment programs for high school students. Students explore engineering and medical careers through college coursework. Students prepare for higher education in engineering and medical fields while completing associate degrees in biology or engineering…

  18. Dual-Income Families.

    ERIC Educational Resources Information Center

    McKitric, Eloise J.

    The impact of economic conditions on two-earner families was examined. Three family types were studied: (1) dual-career family--both the husband and wife are in the labor force but in occupations classified as professional-technical or managerial; (2) dual-earner--both the husband and wife are in the labor force; and (3) traditional family--the…

  19. A dual-heterodyne laser interferometer for simultaneous measurement of linear and angular displacements

    NASA Astrophysics Data System (ADS)

    Yan, Hao; Duan, Hui-Zong; Li, Lin-Tao; Liang, Yu-Rong; Luo, Jun; Yeh, Hsien-Chi

    2015-12-01

    Picometer laser interferometry is an essential tool for ultra-precision measurements in frontier scientific research and advanced manufacturing. In this paper, we present a dual-heterodyne laser interferometer for simultaneously measuring linear and angular displacements with resolutions of picometer and nanoradian, respectively. The phase measurement method is based on cross-correlation analysis and realized by a PXI-bus data acquisition system. By implementing a dual-heterodyne interferometer with a highly symmetric optical configuration, low frequency noises caused by the environmental fluctuations can be suppressed to very low levels via common-mode noise rejection. Experimental results for the dual-heterodyne interferometer configuration presented demonstrate that the noise levels of the linear and angular displacement measurements are approximately 1 pm/Hz1/2 and 0.5 nrad/Hz1/2 at 1 Hz.

  20. NREL Showcases Hydrogen Internal Combustion Engine Bus, Helps DOE Set Standards for Outreach (Fact Sheet)

    SciTech Connect

    Not Available

    2010-11-01

    This fact sheet describes the National Renewable Energy Laboratory's (NREL's) accomplishments in showcasing a Ford hydrogen-powered internal combustion engine (H2ICE) bus at The Taste of Colorado festival in Denver. NREL started using its U.S. Department of Energy-funded H2ICE bus in May 2010 as the primary shuttle vehicle for VIP visitors, members of the media, and new employees. In September 2010, NREL featured the bus at The Taste of Colorado. This was the first major outreach event for the bus. NREL's educational brochure, vehicle wrap designs, and outreach efforts serve as a model for other organizations with DOE-funded H2ICE buses. Work was performed by the Hydrogen Education Group and Market Transformation Group in the Hydrogen Technologies and Systems Center.

  1. 49 CFR Appendix A to Part 665 - Tests To Be Performed at the Bus Testing Facility

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., inspection, and repair. It also should include the removal and reinstallation of the engine and drive train..., low, and split-friction surfaces. The parking brake should be evaluated with the bus parked...

  2. Psychosocial Work Factors, Blood Pressure and Psychological Strain in Male Bus Operators

    PubMed Central

    CENDALES, Boris; USECHE, Sergio; GÓMEZ, Viviola

    2014-01-01

    The research aim was to predict the bus operators’ blood pressure (BP) and psychological strain using a combination of the Job-Demand Control (JDC) and Effort-Reward Imbalance (ERI) models. The study was conducted with a sample of 139 bus operators in the city of Bogotá (Colombia), who answered a questionnaire that included the Job Content Questionnaire (JCQ), the ERI Questionnaire, and the General Health Questionnaire (GHQ). Four consecutive BP readings taken in the workplace were averaged to calculate an estimation of the bus operators’ BP. By conducting multiple linear regressions it was found that, taken together, JDC and ERI models explain 10% (F(11,139)=2,502; p=0.00) of systolic BP variance, and 34% (F(6,139)=8,638; p=0.00) of psychological strain variance. These results suggest that the JDC and ERI predictors provide complementary information which increases the probability of accurately model the bus operators’ health. PMID:24869893

  3. The Yellow School Bus Project: Helping Homeless Students Get Ready for School.

    ERIC Educational Resources Information Center

    Vissing, Yvonne

    2003-01-01

    Describes the Yellow School Bus Project, a community program jointly sponsored by religious, civic, fraternal, business, and nonprofit organizations in Durham, New Hampshire, to provide homeless children with supplies and clothes to help them succeed in school. (PKP)

  4. Study of the impact of automation on productivity in bus-maintenance facilities. Final report

    SciTech Connect

    Sumanth, D.J.; Weiss, H.J.; Adya, B.

    1988-12-01

    Whether or not the various types of automation and new technologies introduced in a bus-transit system really have an impact on productivity is the question addressed in the study. The report describes a new procedure of productivity measurement and evaluation for a county-transit system and provides an objective perspective on the impact of automation on productivity in bus maintenance facilities. The research objectives were: to study the impact of automation on total productivity in transit maintenance facilities; to develop and apply a methodology for measuring the total productivity of a Floridian transit maintenance facility (Bradenton-Manatee County bus maintenance facility which has been introducing automation since 1983); and to develop a practical step-by-step implementation scheme for the total productivity-based productivity measurement system that any bus manager can use. All 3 objectives were successfully accomplished.

  5. Operationally Responsive Space Standard Bus Battery Thermal Balance Testing and Heat Dissipation Analysis

    NASA Technical Reports Server (NTRS)

    Marley, Mike

    2008-01-01

    The focus of this paper will be on the thermal balance testing for the Operationally Responsive Space Standard Bus Battery. The Standard Bus thermal design required that the battery be isolated from the bus itself. This required the battery to have its own thermal control, including heaters and a radiator surface. Since the battery was not ready for testing during the overall bus thermal balance testing, a separate test was conducted to verify the thermal design for the battery. This paper will discuss in detail, the test set up, test procedure, and results from this test. Additionally this paper will consider the methods taken to determine the heat dissipation of the battery during charge and discharge. It seems that the heat dissipation for Lithium Ion batteries is relatively unknown and hard to quantify. The methods used during test and the post test analysis to estimate the heat dissipation of the battery will be discussed.

  6. Optical bus waveguide metallic hard mold fabrication with opposite 45° micro-mirrors

    NASA Astrophysics Data System (ADS)

    Dou, Xinyuan; Wang, Alan Xiaolong; Lin, Xiaohui; Huang, Haiyu; Chen, Ray T.

    2010-02-01

    In this paper, 3-to-3 metallic hard mold for optical bus waveguide with opposite 45° micro-mirrors was successfully fabricated using electroplating method. The optical bus waveguide pre-mold with 45° surfaces before electroplating was prepared using photopolymer SU-8 through tilted exposure process under de-ionized water. Metal nickel was electroplated into SU-8 defined bus waveguide trenches. The 45° slant angles can be well controlled through titled exposure, which have deviations of 0.15° and 0.27° for SU-8 pre-mold and Ni hard mold, respectively. This metallic hard mold provides a convenient way to fabricate the polymeric optical bus waveguide devices through imprint technique.

  7. Research on urban public traffic network with multi-weights based on single bus transfer junction

    NASA Astrophysics Data System (ADS)

    An, Xin-lei; Zhang, Li; Zhang, Jian-gang

    2015-10-01

    Regarding single bus transfer junction as a research object, this paper constructs the urban traffic network models with multi-weights taking different bus lines in bus transfer junction as the network nodes, that is, the urban traffic network with multi-weights is given different properties weights at every edge. According to the method of network split, the complex network with multi-weights is split into several different single weighted complex networks. Then, we study the global synchronization of the new network model by changing congestion degrees, transfers coefficient and passenger flow density between different bus lines. Finally, analytical and simulated results are given to show the impact of different properties weights to the public traffic network balance.

  8. Scheduling bus services in Universiti Teknologi MARA (UiTM) Shah Alam

    NASA Astrophysics Data System (ADS)

    Omar, Mawardi; Ismail, Wan Rosmanira; Oughalime, Ahmed

    2014-09-01

    This study deals with bus scheduling problem in a local public university. Given existing bus daily trips, set of buses used and set of policy, the aims of this study are to optimize the use of buses for in-campus trips and to cover the trip demands. This study is conducted at Universiti Teknologi Mara (UiTM) Shah Alam that involves six-zone trips and a single depot. The bus scheduling problem in UiTM is formulated using the integer programming model and the LINGO 12.0 software is used for solving this bus scheduling model. The results of this model showed that the number of buses can be reduced during off-peak hours. Furthermore, optimal trips can also be identified from the results.

  9. Traffic states and jamming transitions induced by a bus in two-lane traffic flow

    NASA Astrophysics Data System (ADS)

    Nagai, Ryoichi; Nagatani, Takashi; Taniguchi, Naoki

    2005-05-01

    We study the traffic states and jamming transitions induced by a bus (slow car) in a two-lane traffic of cars. We use the dynamic model which is an extended one of the optimal velocity model to take into account the lane changing. The fundamental (flow-density) diagram is presented. The fundamental diagram changes highly by introducing a bus on a two-lane roadway. It is found that there are the six distinct states for the two-lane traffic flow including a bus. The spatio-temporal patterns are presented for the distinct traffic states. The dynamical state of traffic changes with density of cars. It is shown that the dynamical transitions among the distinct traffic states occur at some values of density. The phase diagram (region map) is shown for the two-lane traffic flow including a bus.

  10. Long term application of bus monitoring system to short and medium span bridges and damage detection

    NASA Astrophysics Data System (ADS)

    Miyamoto, Ayaho; Lúcio, Válter J. G.; Emoto, Hisao; Tanaka, Hideaki

    2015-07-01

    In this study, as one solution to the problem for condition assessment of existing short and medium span reinforced/prestressed concrete bridges, a new monitoring method using a public bus as part of a public transit system (bus monitoring system) is proposed, along with safety indices, namely, characteristic deflection, which is relatively free from the influence of dynamic disturbances due to such factors as the roughness of the road surface, and a structural anomaly parameter. A basic study was conducted by using the results of technical verification experiments and numerical analysis simulation. This paper describes the details of not only how to assess the bridge condition by public bus vibration measured in operating on Ube City bus network as a specific example for verify the system but also what kind of consideration we need to apply the system to existing bridges in overseas country.

  11. Ergonomic work analysis of urban bus drivers in Rio de Janeiro city.

    PubMed

    Querido, Aloá; Nogueira, Tainan; Gama, Rafael; Orlando, José

    2012-01-01

    This article is the result of a case study on ergonomic work analysis carried out in an urban bus company located in Ilha do Governador, Rio de Janeiro. The methodology used in this work follows the French-tradition Ergonomic Analysis of the Work (EWA) combined with the best tradition from anglo-saxon ergonomic work analysis. The situated diagnosis was performed to provide relevant information about the work conditions of a bus driver. PMID:22317732

  12. The Ruggedized STD Bus Microcomputer - A low cost computer suitable for Space Shuttle experiments

    NASA Astrophysics Data System (ADS)

    Budney, T. J.; Stone, R. W.

    Previous space flight computers have been costly in terms of both hardware and software. The Ruggedized STD Bus Microcomputer is based on the commercial Mostek/Pro-Log STD Bus. Ruggedized PC cards can be based on commercial cards from more than 60 manufacturers, reducing hardware cost and design time. Software costs are minimized by using standard 8-bit microprocessors and by debugging code using commercial versions of the ruggedized flight boards while the flight hardware is being fabricated.

  13. The Ruggedized STD Bus Microcomputer - A low cost computer suitable for Space Shuttle experiments

    NASA Technical Reports Server (NTRS)

    Budney, T. J.; Stone, R. W.

    1982-01-01

    Previous space flight computers have been costly in terms of both hardware and software. The Ruggedized STD Bus Microcomputer is based on the commercial Mostek/Pro-Log STD Bus. Ruggedized PC cards can be based on commercial cards from more than 60 manufacturers, reducing hardware cost and design time. Software costs are minimized by using standard 8-bit microprocessors and by debugging code using commercial versions of the ruggedized flight boards while the flight hardware is being fabricated.

  14. Dual Credit/Dual Enrollment and Data Driven Policy Implementation

    ERIC Educational Resources Information Center

    Lichtenberger, Eric; Witt, M. Allison; Blankenberger, Bob; Franklin, Doug

    2014-01-01

    The use of dual credit has been expanding rapidly. Dual credit is a college course taken by a high school student for which both college and high school credit is given. Previous studies provided limited quantitative evidence that dual credit/dual enrollment is directly connected to positive student outcomes. In this study, predictive statistics…

  15. Notes from the field: elemental mercury spill in school bus and residence - North Carolina, 2013.

    PubMed

    Langley, Ricky; Hirsch, Anne; McDaniel, Jesse; Lott, Valerie; Shehee, Mina; Migit, Samantha; Dulaney, Anna R; Negron, Jose; Fleischauer, Aaron

    2014-02-14

    On September 16, 2013, the North Carolina Division of Public Health was notified of an elemental (metallic and liquid) mercury spill on a school bus. An elementary student boarded the bus with approximately 1 pound (454 g) of elemental mercury contained in a film canister, which the student had taken from an adult relative who had found it in a neighbor's shed. The canister was handled by several students before the contents spilled on the bus floor. Ten passengers aboard the bus were exposed, including eight students and two staff members. Although elemental mercury is not readily absorbed from skin contact or ingestion, it does vaporize at room temperatures and inhalation of the vapor can be harmful. The bus driver promptly notified school officials. Firefighters and a local hazardous materials team directed decontamination procedures (i.e., changing clothes and washing hands and shoes) for the 10 exposed passengers. The bus was immediately taken out of service and sent for disposal because of its age and the cost of decontamination. PMID:24522097

  16. Exact and Metaheuristic Approaches for a Bi-Objective School Bus Scheduling Problem

    PubMed Central

    Chen, Xiaopan; Kong, Yunfeng; Dang, Lanxue; Hou, Yane; Ye, Xinyue

    2015-01-01

    As a class of hard combinatorial optimization problems, the school bus routing problem has received considerable attention in the last decades. For a multi-school system, given the bus trips for each school, the school bus scheduling problem aims at optimizing bus schedules to serve all the trips within the school time windows. In this paper, we propose two approaches for solving the bi-objective school bus scheduling problem: an exact method of mixed integer programming (MIP) and a metaheuristic method which combines simulated annealing with local search. We develop MIP formulations for homogenous and heterogeneous fleet problems respectively and solve the models by MIP solver CPLEX. The bus type-based formulation for heterogeneous fleet problem reduces the model complexity in terms of the number of decision variables and constraints. The metaheuristic method is a two-stage framework for minimizing the number of buses to be used as well as the total travel distance of buses. We evaluate the proposed MIP and the metaheuristic method on two benchmark datasets, showing that on both instances, our metaheuristic method significantly outperforms the respective state-of-the-art methods. PMID:26176764

  17. Data collection plan for Phase 2 Alternative Fuels Bus Data Collection Program. Final report

    SciTech Connect

    Krenelka, T.

    1993-07-01

    This document constitutes the plan for collecting and reporting data associated with a special set of transit bus demonstrations to be conducted under the Urban Bus Program of the Alternative Motor Fuels Act (AMFA) of 1988. This program, called the Phase 2 Bus Data Collection Program, serves as an adjunct to the Phase I Bus Data Collection Program, collecting detailed data on just a few buses to augment and enhance the Phase 1 data in fulfilling the urban bus requirements of AMFA. Demonstrations will be conducted at a few transit system locations throughout the US and will use alternative fuels and associated technologies to reduce undesirable transit bus exhaust emissions. Several organizations will be involved in the data collection; NREL will manage the program, analyze and store vehicle data, and make these data available through the Alternative Fuels Data Center. This information will enable transit agencies, equipment manufacturers, fuel suppliers, and government policy makers to make informed decisions about buying and using alternative fuels.

  18. Analysis of the University of Texas at Austin compressed natural gas demonstration bus. Interim research report

    SciTech Connect

    Wu, C.M.; Matthews, R.; Euritt, M.

    1994-06-01

    A demonstration compressed natural gas (CNG) bus has been operating on The University of Texas at Austin shuttle system since 1992. This CNG vehicle, provided by the Blue Bird Company, was an opportunity for the University to evaluate the effectiveness of a CNG bus for shuttle operations. Three basic operating comparisons were made: (1) fuel consumption, (2) tire wear, and (3) vehicle performance. The bus was equipped with a data logger, which was downloaded regularly, for trip reports. Tire wear was monitored regularly, and performance tests were conducted at the Natural Gas Vehicle Technology Center. Overall, the data suggest that fuel costs for the CNG bus are comparable to those for University diesel buses. This is a result of the lower fuel price for natural gas. Actual natural gas fuel consumption was higher for the CNG buses than for the diesel buses. Due to weight differences, tire wear was much less on the CNG buses. Finally, after installation of a closed-loop system, the CNG bus out-performed the diesel bus on acceleration, grade climbing ability, and speed.

  19. Exact and Metaheuristic Approaches for a Bi-Objective School Bus Scheduling Problem.

    PubMed

    Chen, Xiaopan; Kong, Yunfeng; Dang, Lanxue; Hou, Yane; Ye, Xinyue

    2015-01-01

    As a class of hard combinatorial optimization problems, the school bus routing problem has received considerable attention in the last decades. For a multi-school system, given the bus trips for each school, the school bus scheduling problem aims at optimizing bus schedules to serve all the trips within the school time windows. In this paper, we propose two approaches for solving the bi-objective school bus scheduling problem: an exact method of mixed integer programming (MIP) and a metaheuristic method which combines simulated annealing with local search. We develop MIP formulations for homogenous and heterogeneous fleet problems respectively and solve the models by MIP solver CPLEX. The bus type-based formulation for heterogeneous fleet problem reduces the model complexity in terms of the number of decision variables and constraints. The metaheuristic method is a two-stage framework for minimizing the number of buses to be used as well as the total travel distance of buses. We evaluate the proposed MIP and the metaheuristic method on two benchmark datasets, showing that on both instances, our metaheuristic method significantly outperforms the respective state-of-the-art methods. PMID:26176764

  20. Composite Bus Structure for the SMEX/WIRE Satellite

    NASA Technical Reports Server (NTRS)

    Rosanova, Giulio G.

    1998-01-01

    In an effort to reduce the weight and optimize the structural design of the Small Explorer (SMEX) Wide-Field Infrared Explorer (WIRE) spacecraft, it has become desirable to change the material and construction from mechanically fastened aluminum structure to a fully bonded fiber-reinforced composite (FRC) structure. GSFC has developed the WIRE spacecraft structural bus design concept, including the instrument and launch vehicle requirements. The WIRE Satellite is the fifth of a series of SMEX satellites to be launched once per year. GSFC has chosen Composite Optics Inc. (COI) as the prime contractor for the development and procurement of the WIRE composite structure. The detailed design of the fully bonded FRC structure is based on COI's Short Notice Accelerated Production SATellite ("SNAPSAT") approach. SNAPSAT is a state of the art design and manufacturing technology for advanced composite materials which utilizes flat-stock detail parts bonded together to produce a final structural assembly. The structural design approach adopted for the WIRE structure provides a very viable alternative to both traditional aluminum construction as well as high tech. molded type composite structures. This approach to composite structure design is much less costly than molded or honeycomb sandwich type composite construction, but may cost slightly more than conventional aluminum construction on the subsystem level. However on the overall program level the weight saving achieved is very cost effective, since the primary objective is to allocate more mass for science payloads.

  1. Blood pressure and blood lead concentration in bus drivers

    SciTech Connect

    Sharp, D.S.; Osterloh, J.; Becker, C.E.; Bernard, B.; Smith, A.H.; Fisher, J.M.; Syme, S.L.; Holman, B.L.; Johnston, T.

    1988-06-01

    San Francisco bus drivers have an increased prevalence of hypertension. This study examined relationships between blood lead concentration and blood pressure in 342 drivers. The analysis reported in this study was limited to subjects not on treatment for hypertension (n = 288). Systolic and diastolic pressure varied from 102 to 173 mm Hg and from 61 to 105 mm Hg, respectively. The blood lead concentration varied from 2 to 15 ..mu..g/dL. The relationship between blood pressure and the logarithm of blood lead concentration was examined using multiple regression analysis. Covariates included age, body mass index, sex, race, and caffeine intake. The largest regression coefficient relating systolic blood pressure and blood lead concentration was 1.8 mm Hg/ln (..mu..g/dL). The coefficient for diastolic blood pressure was 2.5 mm Hg/ln (..mu..g/dL). These findings suggest effects of lead exposure at lower blood lead concentrations than those concentrations that have previously been linked with increases in blood pressure.

  2. Oxygen Generation System Laptop Bus Controller Flight Software

    NASA Technical Reports Server (NTRS)

    Rowe, Chad; Panter, Donna

    2009-01-01

    The Oxygen Generation System Laptop Bus Controller Flight Software was developed to allow the International Space Station (ISS) program to activate specific components of the Oxygen Generation System (OGS) to perform a checkout of key hardware operation in a microgravity environment, as well as to perform preventative maintenance operations of system valves during a long period of what would otherwise be hardware dormancy. The software provides direct connectivity to the OGS Firmware Controller with pre-programmed tasks operated by on-orbit astronauts to exercise OGS valves and motors. The software is used to manipulate the pump, separator, and valves to alleviate the concerns of hardware problems due to long-term inactivity and to allow for operational verification of microgravity-sensitive components early enough so that, if problems are found, they can be addressed before the hardware is required for operation on-orbit. The decision was made to use existing on-orbit IBM ThinkPad A31p laptops and MIL-STD-1553B interface cards as the hardware configuration. The software at the time of this reporting was developed and tested for use under the Windows 2000 Professional operating system to ensure compatibility with the existing on-orbit computer systems.

  3. A bus stop shelter evaluated from the user's perspective.

    PubMed

    Ely, Vera Helena Moro Bins; de Oliveira, Jonara Machado; Logsdon, Louise

    2012-01-01

    This study aims to evaluate the current bus stop shelter model used in Florianópolis, Brazil, through a functional analysis--focused in the relationship between the shelter, the users and their activities--and also to analyse users' perceptions. The methodology consisted of exploratory visits, anthropometric analysis, observation and interviews. The exploratory visit intended to survey the physical characteristics of the shelter (dimensions, materials, colors, displayed information) and its position on the sidewalk. The anthropometric analysis was made to verify whether the dimensions of the shelters were adequate to users' needs. The observation provided data for the analysis of users' behavior, which involved a biomechanical study of their postures, an ownership/occupancy analysis in terms of territoriality and studies about spatial requirements of interpersonal relations (proxemics). The interviews helped to analyze how the user perceives the quality of some of the main functions of the shelter: to provide physical and psychological comfort and to display information about the public transportation system. As a result, the overall conclusion is that shelters do not meet users' needs. Recommendations are provided in order to improve physical and psychological comfort and to display relevant information about the transportation system. PMID:22316887

  4. Building a High Performance Metadata Broker using Clojure, NoSQL and Message Queues

    NASA Astrophysics Data System (ADS)

    Truslove, I.; Reed, S.

    2013-12-01

    In practice, Earth and Space Science Informatics often relies on getting more done with less: fewer hardware resources, less IT staff, fewer lines of code. As a capacity-building exercise focused on rapid development of high-performance geoinformatics software, the National Snow and Ice Data Center (NSIDC) built a prototype metadata brokering system using a new JVM language, modern database engines and virtualized or cloud computing resources. The metadata brokering system was developed with the overarching goals of (i) demonstrating a technically viable product with as little development effort as possible, (ii) using very new yet very popular tools and technologies in order to get the most value from the least legacy-encumbered code bases, and (iii) being a high-performance system by using scalable subcomponents, and implementation patterns typically used in web architectures. We implemented the system using the Clojure programming language (an interactive, dynamic, Lisp-like JVM language), Redis (a fast in-memory key-value store) as both the data store for original XML metadata content and as the provider for the message queueing service, and ElasticSearch for its search and indexing capabilities to generate search results. On evaluating the results of the prototyping process, we believe that the technical choices did in fact allow us to do more for less, due to the expressive nature of the Clojure programming language and its easy interoperability with Java libraries, and the successful reuse or re-application of high performance products or designs. This presentation will describe the architecture of the metadata brokering system, cover the tools and techniques used, and describe lessons learned, conclusions, and potential next steps.

  5. Dual-Earner Families.

    ERIC Educational Resources Information Center

    Aldous, Joan, Ed.

    1981-01-01

    Presents eight articles focused on dual-earner families in terms of career choices, family adjustment problems, role conflicts, marital relationships, housework activities, and preschool children's sex role identities. (HLM)

  6. N log N dual shuffle-exchange network with error-correcting routing

    NASA Astrophysics Data System (ADS)

    Liew, Soung C.; Lee, Tony T.

    1994-02-01

    This paper describes a dual shuffle-exchange switching network (DSN) that makes use of the principle of error-correcting routing. For motivation, parallels are drawn between error-correcting routing in switching and error-correcting coding in transmission. Based on a novel error-correcting and self-routing algorithm, we show by analysis and simulation that the DSN can achieve the Shanon's lower bound N log N on switch complexity while satisfying four desirable criteria: 1) self-routing property; 2) no queueing of packets at the inputs or inside the switch; 3) arbitrarily small packet-loss probability; 4) close-to-100% throughput. Different implementations of the basic DSN concept and their trade-offs are discussed.

  7. SEDS MIL-STD-1773 fiber optic data bus: Proton irradiation test results and spaceflight SEU data

    SciTech Connect

    LaBel, K.A.; Stassinopoulos, E.G.; Miller, J.T. ); Marshall, P. ); Dale, C. ); Crabtree, C.M. ); Gates, M.M. )

    1993-12-01

    The Small Explorer Data System (SEDS) was launched in July of 1992 as part of the Solar Anomalous Magnetospheric Particle Explorer (SAMPEX) mission. The SEDS utilizes NASA's first MIL-STD-1773 Fiber Optic Multiplexed Data Bus (or 1773 bus) to communicate with other spacecraft subsystems in the space environment. The 1773 bus is the fiber optic version of the MIL-STD-1553 Data Bus, a electronic wire bus used in many avionics applications. The authors present proton test and space flight single event effect data for NASA's first fiber optic data bus. Bit error rate predictions based on a new proton direct ionization model agree well with flight data for proton belt and solar flare effects.

  8. Conceptual Design of the TPF-O SC Bus

    NASA Technical Reports Server (NTRS)

    Purves, Lloyd R.

    2007-01-01

    One option under current study for the Terrestrial Planet Finder-Occulter (TPF-O) observatory shares some key features of the Hubble Space Telescope (HST). Both are space telescopes with a primary mirror aperture of around 2.4 meters and designed to observe in the visible to near infrared range of wavelengths, with the major difference in science capability being that TPF-O has an areal FOV on the order of 100 times larger than that of HST. This larger FOV, whose science camera is also expected to provide fine guidance, and other mission differences, mean that most TPF-O SC bus subsystems will have very different requirements than those of HST. Unlike HST in LEO, TPF-O is designed to operate in an orbit around the Sun-Earth lagrange 2 (SEL2) point. The longer communications range to SEL2 and the large FOV require much higher performance data processing and communications than HST. Maintaining a SEL2 orbit requires TPF-O, unlike HST, to have a propulsion system. TPF-O will have a specialized tracking system that allows the formation flying occulter to maintain its required position. However, despite these additional features, the velocity required for reaching SEL2 and the limited capabilities of affordable launch vehicles require TPF-O to have a compact and low-mass design relative to HST. Finally, TPF-O may utilize a modular design to reduce development cost and, if it required, allow servicing using approaches different from those of HST.

  9. Bus Automata For Intelligent Robots And Computer Vision

    NASA Astrophysics Data System (ADS)

    Rothstein, Jerome

    1988-02-01

    Bus automata (BA's) are arrays of automata, each controlling a module of a global interconnection network, an automaton and its module constituting a cell. Connecting modules permits cells to become effectively nearest neighbors even when widely separated. This facilitates parallelism in computation far in excess of that allowed by the "bucket-brigade" communication bottleneck of traditional cellular automata (CA's). Distributed information storage via local automaton states permits complex parallel data processing for rapid pattern recognition, language parsing and other distributed computation at systolic array rates. Global BA architecture can be entirely changed in the time to make one cell state transition. The BA is thus a neural model (cells correspond to neurons) with network plasticity attractive for brain models. Planar (chip) BA's admitting optical input (phototransistors) become powerful retinal models. The distributed input pattern is optically fed directly to distributed local memory, ready for distributed processing, both "retinally" and cooperatively with other BA chips ("brain"). This composite BA can compute control signals for output organs, and sensory inputs other than visual can be utilized similarly. In the BA retina is essentially brain, as in mammals (retina and brain are embryologically the same). The BA can also model opto-motor response (frogs, insects) or sonar response (dolphins, bats), and is proposed as the model of choice for the brains of future intelligent robots and for computer eyes with local parallel image processing capability. Multidimensional formal languages are introduced, corresponding to BA's and patterns the way generative grammars correspond to sequential machines, and applied to fractals and their recognition by BA's.

  10. Smoking close to others and butt littering at bus stops: pilot observational study.

    PubMed

    Wilson, Nick; Oliver, Jane; Thomson, George

    2014-01-01

    Background. Transportation settings such as bus stops and train station platforms are increasingly the target for new smokefree legislation. Relevant issues include secondhand smoke exposure, nuisance, litter, fire risks and the normalization of smoking. We therefore aimed to pilot study aspects of smoking behavior and butt disposal at bus stops. Methods. Systematic observation of smoking and butt disposal by smokers at bus stops. The selection of 11 sites was a mix of convenience and purposeful (bus stops on main routes) in two New Zealand cities. Results. During 27 h of observation, a total of 112 lit cigarettes were observed being smoked. Smoking occurred in the presence of: just adults (46%), both young people and adults (44%), just young people (6%) and alone (5%). An average of 6.3 adults and 3.8 young people were present at the bus stops while smoking occurred, at average minimum distances of 1.7 and 2.2 m respectively. In bus stops that included an enclosed shelter, 33% of the cigarettes were smoked inside the shelter with others present. Littering was the major form of cigarette disposal with 84% of cigarettes smoked being littered (95% CI; 77%-90%). Also, 4% of disposals were into vegetation, which may pose a fire risk. Conclusions. This pilot study is limited by its small size and various methodological aspects but it appears to be a first attempt to provide observational evidence around smoking at bus stops. The issues described could be considered by policy makers who are investigating national smokefree laws or by-laws covering transportation settings. PMID:24688851

  11. Smoking close to others and butt littering at bus stops: pilot observational study

    PubMed Central

    Oliver, Jane; Thomson, George

    2014-01-01

    Background. Transportation settings such as bus stops and train station platforms are increasingly the target for new smokefree legislation. Relevant issues include secondhand smoke exposure, nuisance, litter, fire risks and the normalization of smoking. We therefore aimed to pilot study aspects of smoking behavior and butt disposal at bus stops. Methods. Systematic observation of smoking and butt disposal by smokers at bus stops. The selection of 11 sites was a mix of convenience and purposeful (bus stops on main routes) in two New Zealand cities. Results. During 27 h of observation, a total of 112 lit cigarettes were observed being smoked. Smoking occurred in the presence of: just adults (46%), both young people and adults (44%), just young people (6%) and alone (5%). An average of 6.3 adults and 3.8 young people were present at the bus stops while smoking occurred, at average minimum distances of 1.7 and 2.2 m respectively. In bus stops that included an enclosed shelter, 33% of the cigarettes were smoked inside the shelter with others present. Littering was the major form of cigarette disposal with 84% of cigarettes smoked being littered (95% CI; 77%–90%). Also, 4% of disposals were into vegetation, which may pose a fire risk. Conclusions. This pilot study is limited by its small size and various methodological aspects but it appears to be a first attempt to provide observational evidence around smoking at bus stops. The issues described could be considered by policy makers who are investigating national smokefree laws or by-laws covering transportation settings. PMID:24688851

  12. Bus Stops and Pedestrian-Motor Vehicle Collisions in Lima, Peru: A Matched Case-Control Study

    PubMed Central

    Quistberg, D. Alex; Koepsell, Thomas D.; Johnston, Brian D.; Boyle, Linda Ng; Miranda, J. Jaime; Ebel, Beth E.

    2015-01-01

    Objective To evaluate the relationship between bus stop characteristics and pedestrian-motor vehicle collisions. Design Matched case-control study where the units of study were pedestrian crossing. Setting Random sample of 11 police commissaries in Lima, Peru. Data collection occurred from February, 2011 to September, 2011. Participants 97 intersection cases representing 1,134 collisions and 40 mid-block cases representing 469 collisions that occurred between October, 2010 and January, 2011 and their matched controls. Main Exposures Presence of a bus stop and specific bus stop characteristics. Main Outcome Occurrence of a pedestrian-motor vehicle collision. Results Intersections with bus stops were three times more likely to have a pedestrian-vehicle collision (OR 3.28, 95% CI 1.53-7.03), relative to intersections without bus stops. Both formal and informal bus stops were associated with a higher odds of a collision at intersections (OR 6.23, 95% CI 1.76-22.0 and OR 2.98, 1.37-6.49). At mid-block sites, bus stops on a bus-dedicated transit lane were also associated with collision risk (OR 2.36, 95% CI 1.02-5.42). All bus stops were located prior to the intersection, contrary to practices in most high income countries. Conclusions In urban Lima, the presence of a bus stop was associated with a three-fold increase in risk of a pedestrian collision. The highly competitive environment among bus companies may provide an economic incentive for risky practices such as dropping off passengers in the middle of traffic and jockeying for position with other buses. Bus stop placement should be considered to improve pedestrian safety. PMID:24357516

  13. Research, development and demonstration of a fuel cell/battery powered bus system. Phase 1, Final report

    SciTech Connect

    1990-02-28

    Purpose of the Phase I effort was to demonstrate feasibility of the fuel cell/battery system for powering a small bus (under 30 ft or 9 m) on an urban bus route. A brassboard powerplant was specified, designed, fabricated, and tested to demonstrate feasibility in the laboratory. The proof-of-concept bus, with a powerplant scaled up from the brassboard, will be demonstrated under Phase II.

  14. The ACP (Advanced Computer Program) Branch bus and real-time applications of the ACP multiprocessor system

    SciTech Connect

    Hance, R.; Areti, H.; Atac, R.; Biel, J.; Cook, A.; Fischler, M.; Gaines, I.; Husby, D.; Nash, T.; Zmuda, T.

    1987-05-08

    The ACP Branchbus, a high speed differential bus for data movement in multiprocessing and data acquisition environments, is described. This bus was designed as the central bus in the ACP multiprocessing system. In its full implementation with 16 branches and a bus switch, it will handle data rates of 160 MByte/sec and allow reliable data transmission over inter rack distances. We also summarize applications of the ACP system in experimental data acquisition, triggering and monitoring, with special attention paid to FASTBUS environments.

  15. Determinants of exposure to fine particulate matter (PM 2.5) for waiting passengers at bus stops

    NASA Astrophysics Data System (ADS)

    Hess, Daniel Baldwin; Ray, Paul David; Stinson, Anne E.; Park, JiYoung

    2010-12-01

    This research evaluates commuter exposure to particulate matter during pre-journey commute segments for passengers waiting at bus stops by investigating 840 min of simultaneous exposure levels, both inside and outside seven bus shelters in Buffalo, New York. A multivariate regression model is used to estimate the relation between exposure to particulate matter (PM 2.5 measured in μg m -3) and three vectors of determinants: time and location, physical setting and placement, and environmental factors. Four determinants have a statistically significant effect on particulate matter: time of day, passengers' waiting location, land use near the bus shelter, and the presence of cigarette smoking at the bus shelter. Model results suggest that exposure to PM 2.5 inside a bus shelter is 2.63 μg m -3 (or 18 percent) higher than exposure outside a bus shelter, perhaps due in part to the presence of cigarette smoking. Morning exposure levels are 6.51 μg m -3 (or 52 percent) higher than afternoon levels. Placement of bus stops can affect exposure to particulate matter for those waiting inside and outside of shelters: air samples at bus shelters located in building canyons have higher particulate matter than bus shelters located near open space.

  16. Implementation of Ada protocols on Mil-STD-1553 B data bus

    NASA Technical Reports Server (NTRS)

    Ruhman, Smil; Rosemberg, Flavia

    1986-01-01

    Standardization activity of data communication in avionic systems started in 1968 for the purpose of total system integration and the elimination of heavy wire bundles carrying signals between various subassemblies. The growing complexity of avionic systems is straining the capabilities of MIL-STD-1553 B (first issued in 1973), but a much greater challenge to it is posed by Ada, the standard language adopted for real-time, computer embedded-systems. Hardware implementation of Ada communication protocols in a contention/token bus or token ring network is proposed. However, during the transition period when the current command/response multiplex data bus is still flourishing and the development environment for distributed multi-computer Ada systems is as yet lacking, a temporary accomodation of the standard language with the standard bus could be very useful and even highly desirable. By concentrating all status informtion and decisions at the bus controller, it was found to be possible to construct an elegant and efficient harware impelementation of the Ada protocols at the bus interface. This solution is discussed.

  17. The Design of a Fault-Tolerant COTS-Based Bus Architecture

    NASA Technical Reports Server (NTRS)

    Chau, Savio N.; Alkalai, Leon; Burt, John B.; Tai, Ann T.

    1999-01-01

    In this paper, we report our experiences and findings on the design of a fault-tolerant bus architecture comprised of two COTS buses, the IEEE 1394 and the 12C. This fault-tolerant bus is the backbone system bus for the avionics architecture of the X2000 program at the Jet Propulsion Laboratory. COTS buses are attractive because of the availability of low cost commercial products. However, they are not specifically designed for highly reliable applications such as long-life deep-space missions. The X2000 design team has devised a multi-level fault tolerance approach to compensate for this shortcoming of COTS buses. First, the approach enhances the fault tolerance capabilities of the IEEE 1394 and 12 C buses by adding a layer of fault handling hardware and software. Second, algorithms are developed to enable the IEEE 1394 and the 12 C buses assist each other to isolate and recovery from faults. Third, the set of IEEE 1394 and 12 C buses is duplicated to further enhance system reliability. The X2000 design team has paid special attention to guarantee that all fault tolerance provisions will not cause the bus design to deviate from the commercial standard specifications. Otherwise, the economic attractiveness of using COTS will be diminished. The hardware and software design of the X2000 fault-tolerant bus are being implemented and flight hardware will be delivered to the ST4 and Europa Orbiter missions.

  18. The capacity of two neighbour intersections considering the influence of the bus stop

    NASA Astrophysics Data System (ADS)

    Zhao, Xiao-mei; Gao, Zi-you; Li, Ke-ping

    2008-07-01

    In this paper, we use a two-lane CA model to investigate the effect of a bus stop between two neighbouring intersections on the capacity of the bus. Both the case of a bus stop with a special stopping lane and that of one without are considered. The capacity versus the distance LB( LD) between the stop and the upstream (downstream) intersection is studied, with respect to the entering probability Pe and the traffic light cycle T. It is found that a bus stop near an intersection can act as a bottleneck and cause a drop in the capacity when the LB (or LD) is below a critical point L(or L). However, the situation when the stop is located near the downstream intersection is worse than that of the upstream one. Furthermore, the simulation results show that the negative effect varies with the increase of the cycle time T and the capacity can be maximized by adjusting T. Comparisons between the two cases suggest that the stopping lane can improve the capacity to some extent. These results mean that the capacity can be exploited by changing the position of the bus stop or the cycle time, and adding a stopping lane if necessary. These findings may be useful in offering scientific guidance for the management and design of traffic networks.

  19. Fault Location for Transmission Lines with Voltage and Current Measurements at One Bus

    NASA Astrophysics Data System (ADS)

    Xiu, Wanjing; Liao, Yuan

    2014-10-01

    This paper presents a novel fault location method for transmission lines. The proposed method extends an existing method to locate faults by employing voltage and current measurements at one bus, which can be the bus of the faulted line or be far away from the faulted line. The method is applicable if a loop exists that encloses the faulted line, and the bus, of which the voltage is used, and the branch, of which the current is used. The during-fault positive-sequence bus impedance matrix is derived. Then superimposed voltages and currents due to the fault are expressed as a function of fault location and related transfer and driving point impedances. Consequently, the fault location can be evaluated using the obtained measurements. The distributed parameter line model is adopted to consider the shunt capacitances of the line. The proposed method is independent of fault resistance and fault type. Simulation studies have been carried out based on a 27-bus power system, and promising results have been achieved.

  20. GENERAL: Combined bottleneck effect of on-ramp and bus stop in a cellular automaton model

    NASA Astrophysics Data System (ADS)

    Song, Yu-Kun; Zhao, Xiao-Mei

    2009-12-01

    The combined bottleneck effect is investigated by modeling traffic systems with an on-ramp and a nearby bus stop in a two-lane cellular automaton model. Two cases, i.e. the bus stop locates in the downstream section of the on-ramp and the bus stop locates in the upstream section of the on-ramp, are considered separately. The upstream flux and downstream flux of the main road, as well as the on-ramp flux are analysed in detail, with respect to the entering probabilities and the distance between the on-ramp and the bus stop. It is found that the combination of the two bottlenecks causes the capacity to drop off, because the vehicles entering the main road from the on-ramp would interweave with the stopping (pulling-out) buses in the downstream (upstream) case. The traffic conflict in the former case is much heavier than that in the latter, causing the downstream main road to be utilized inefficiently. This suggests that the bus stop should be set in the upstream section of the on-ramp to enhance the capacity. The fluxes both on the main road and on the on-ramp vary with the distance between the two bottlenecks in both cases. However, the effects of distance disappear gradually at large distances. These findings might give some guidance to traffic optimization and management.