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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.

  2. 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

  3. Radiation-Tolerant Dual Data Bus

    NASA Technical Reports Server (NTRS)

    Kinstler, Gary A.

    2007-01-01

    An architecture, and a method of utilizing the architecture, have been proposed to enable error-free operation of a data bus that includes, and is connected to, commercial off-the-shelf (COTS) circuits and components that are inherently susceptible to singleevent upsets [SEUs (bit flips caused by impinging high-energy particles and photons)]. The architecture and method are applicable, more specifically, to data-bus circuitry based on the Institute for Electrical and Electronics Engineers (IEEE) 1394b standard for a high-speed serial bus.

  4. 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.

  5. 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.

  6. 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

  7. Multi-Purpose Low Voltage Dual Output DC-DC Converter For 100V Power Bus Telecom Platform

    NASA Astrophysics Data System (ADS)

    Galiana, D.; Mollard, J. M.

    2011-10-01

    The decreasing supply voltages of digital electronic and high speed ADC (Analog to Digital Converter) and DAC (Digital to Analog Converter) require flexible and high current secondary power distribution system. In the frame of the Inmarsat I-XL program, a 12 kW geomobile SatCom satellite, with 100 V regulated power bus, a multi purpose dual output converter was developed for the payload processor as a building block. After a short introduction on the main performance requirements, the baseline architecture is presented. The main drivers of the architecture are reliability, adjustability, radiation tolerant and single event free, volume and mass. The combination of all these constraints highlights the need of significant breakthrough in various domains. Many research results related to packaging and power electronic topics are brought up. These results directly drive the adopted solution presented in the next step followed by a description of the integration of the defined building block in the Inmarsat I-XL payload IP (Integrated Processor). Finally, the main electrical performances such as output ripple and spikes, load step transient and stability are summarized.

  8. 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.

  9. Concurrent array-based queue

    SciTech Connect

    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.

  10. 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.

  11. 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.

  12. Message passing with queues and channels

    DOEpatents

    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.

  13. 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.

  14. 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…

  15. DATAC bus monitor

    NASA Technical Reports Server (NTRS)

    Novacki, Stanley M., III; Thomas, Robert J., Jr.

    1988-01-01

    The Digital Autonomous Terminal Access Communications (DATAC) bus is a multiple transmitter data bus developed to interconnect various aircraft systems. A typical DATAC bus installation for the NASA B-737 aircraft is shown. A bus monitor unit was developed for the DATAC data bus. The bus monitor unit consists of two systems: A Zilog Z8002 based S100 bus microcomputer system that connects to a DATAC terminal and receives data appearing on the bus, and an IMB PC-compatible computer used to display and interpret that data. Test results of the existing bus monitor have indicated areas for improvement. The most obvious improvement is to increase the speed of the data transfers between the S100 and the MS-DOS systems.

  16. 76 FR 37184 - Discretionary Bus and Bus Facilities Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-24

    ... Federal Transit Administration Discretionary Bus and Bus Facilities Program AGENCY: Federal Transit Administration (FTA), DOT. ACTION: Notice of availability of FTA state of good repair bus and bus facilities...) announces the availability of discretionary Section 5309 Bus and Bus Facilities grant funds in support...

  17. 75 FR 52054 - Bus and Bus Facilities Discretionary Program Funds

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-24

    ... Federal Transit Administration Bus and Bus Facilities Discretionary Program Funds AGENCY: Federal Transit Administration (FTA), DOT. ACTION: Bus and Bus Facilities Livability program announcement of project selections... selection of projects funded with Bus and Bus Facilities program funds in support of DOT's...

  18. 75 FR 23843 - Discretionary Bus and Bus Facilities Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-04

    ... Federal Transit Administration Discretionary Bus and Bus Facilities Program AGENCY: Federal Transit Administration (FTA), DOT. ACTION: Notice of Availability of FTA State of Good Repair Bus and Bus Facilities...) announces the availability of discretionary Section 5309 Bus and Bus Facilities grant funds in support...

  19. 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)

  20. Message passing with queues and channels

    SciTech Connect

    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.

  1. Hydrogen powered bus

    ScienceCinema

    None

    2016-07-12

    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

  2. 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…

  3. 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.

  4. 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)

  5. 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)

  6. Bus.py

    SciTech Connect

    Hansen, Timothy; Palmintier, Bryan; Hale, Elaine; Jones, Wesley

    2014-07-21

    GridLAB-D is an agent? based distribution system simulation environment that allows fine-grained end-user models, including geospatial and network topology detail. GridLAB-D addresses the lack of runtime interaction by designing a flexible communication interface, Bus.py (pronounced bus-dot-pie), that uses Python to pass messages between one or more GridLAB-D instances and a Smart Grid simulator.

  7. 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.

  8. Savannah River bus project

    SciTech Connect

    Summers, W.A.

    1998-08-01

    The H2Fuel Bus is the world`s first hybrid hydrogen electric transit bus. It was developed through a public/private partnership involving several leading technology and industrial organizations in the Southeast, with primary funding and program management provided by the Department of Energy. The primary goals of the project are to gain valuable information on the technical readiness and economic viability of hydrogen buses and to enhance the public awareness and acceptance of emerging hydrogen technologies. The bus has been operated by the transit agency in Augusta, Georgia since April, 1997. It employs a hybrid IC engine/battery/electric drive system, with onboard hydrogen fuel storage based on the use of metal hydrides. Initial operating results have demonstrated an overall energy efficiency (miles per Btu) of twice that of a similar diesel-fueled bus and an operating range twice that of an all-battery powered electric bus. Tailpipe emissions are negligible, with NOx less than 0.2 ppm. Permitting, liability and insurance issues were addressed on the basis of extensive risk assessment and safety analyses, with the inherent safety characteristic of metal hydride storage playing a major role in minimizing these concerns. Future plans for the bus include continued transit operation and use as a national testbed, with potential modifications to demonstrate other hydrogen technologies, including fuel cells.

  9. Queues on narrow roads and in airplanes

    NASA Astrophysics Data System (ADS)

    Frette, Vidar; Hemmer, Per C.

    2011-03-01

    We consider N particles with unidirectional motion in one dimension. The particles never pass each other, and they are distinguishable (labelled). We have studied two types of particle interactions, both of which lead to queue formation due to bottlenecks. There are variations in queue structure from particle scale up to system size. We are interested in quantities obtained after averaging over all N! permutations of particles.

  10. 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.

  11. Preventing messaging queue deadlocks in a DMA environment

    SciTech Connect

    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.

  12. 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

  13. 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

  14. 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).

  15. 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.

  16. 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…

  17. 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…

  18. 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…

  19. 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.

  20. 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.

  1. Multiplex data bus simulator

    SciTech Connect

    Garbo, D.L.

    1983-01-01

    A multiplex data-bus simulator for analyzing multiprocessor designs is presented. The simulator was designed to be user-friendly, thus allowing a multiprocessor designer to enter various configuration inputs in a concise and orderly fashion through the use of menus. The designer is also provided a method of visualizing a message traffic flow through the use of graphical representation of events. 3 references.

  2. 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... discretionary Section 5309 Bus and Bus Facilities grant and New Starts funds in support of the Department...

  3. 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…

  4. Improving School Bus Driver Performance.

    ERIC Educational Resources Information Center

    Farmer, Ernest

    This reference source is intended to assist the school bus driver training instructor in course preparation. Instructional units for program planning each contain pertinent course questions, a summary, and evaluation questions. Unit 1, "Introduction to the School Bus Driver Training Program," focuses on basic course objectives and requirements and…

  5. 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…

  6. 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.

  7. Standard satellite data bus initiative

    NASA Astrophysics Data System (ADS)

    Spinney, Timothy; Yousef, Hassan

    The USAF Space Technology Center manages programs to reduce satellite costs through the appropriate use of microelectronics standardization. Ongoing programs such as the Standard Spacecraft Memory Module and Generic VHSIC Spaceborne Computer have provided an insight into the value of standardization and led to an initiative to coordinate microelectronics development around a standard satellite data bus, which should reduce costs by eliminating program- and contractor-unique interfaces, increasing production runs, and developing generic test equipment. Current efforts focus on the satellite housekeeping functions, and it is expected that the mission payload would also use this data bus. Based on existing housekeeping data-traffic requirements, several candidates have been identified for the standard data bus. The two candidates selected for further work are the ANSI X3T9.5 data bus and the linear token-passing data bus being proposed as part of the Advanced Tactical Fighter effort.

  8. Bus accident analysis of routes with/without bus priority.

    PubMed

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

    2014-04-01

    This paper summarises findings on road safety performance and bus-involved accidents in Melbourne along roads where bus priority measures had been applied. Results from an empirical analysis of the accident types revealed significant reduction in the proportion of accidents involving buses hitting stationary objects and vehicles, which suggests the effect of bus priority in addressing manoeuvrability issues for buses. A mixed-effects negative binomial (MENB) regression and back-propagation neural network (BPNN) modelling of bus accidents considering wider influences on accident rates at a route section level also revealed significant safety benefits when bus priority is provided. Sensitivity analyses done on the BPNN model showed general agreement in the predicted accident frequency between both models. The slightly better performance recorded by the MENB model results suggests merits in adopting a mixed effects modelling approach for accident count prediction in practice given its capability to account for unobserved location and time-specific factors. A major implication of this research is that bus priority in Melbourne's context acts to improve road safety and should be a major consideration for road management agencies when implementing bus priority and road schemes.

  9. 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.

  10. 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.

  11. 76 FR 68819 - State of Good Repair Bus and Bus Facilities Discretionary Program Funds

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-07

    ... Federal Transit Administration State of Good Repair Bus and Bus Facilities Discretionary Program Funds AGENCY: Federal Transit Administration (FTA), DOT. ACTION: State of Good Repair Bus and Bus Facilities... Transit Administration (FTA) announces the selection of projects funded with Section 5309 Bus and...

  12. 75 FR 74134 - State of Good Repair Bus and Bus Facilities Discretionary Program Funds

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-30

    ... Federal Transit Administration State of Good Repair Bus and Bus Facilities Discretionary Program Funds AGENCY: Federal Transit Administration (FTA), DOT. ACTION: State of Good Repair Bus and Bus Facilities... Transit Administration (FTA) announces the selection of projects funded with Section 5309 Bus and...

  13. 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

  14. 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)

  15. 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.

  16. 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

  17. SCHOOL BUS GARAGES, 1966 REVISION.

    ERIC Educational Resources Information Center

    JOHNSON, HERBERT F.

    STANDARDS AND RECOMMENDATIONS ARE GIVEN FOR THE DESIGN AND CONSTRUCTION OF SCHOOL BUS GARAGES INCLUDING BRIEF DISCUSSIONS OF--(1) SITE DEVELOPMENT, (2) DESIGN AND CONSTRUCTION, AND (3) MECHANICAL (HEATING, PLUMBING, AND VENTILATION) AND ELECTRICAL FACTORS. (JT)

  18. 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.

  19. 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.

  20. 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.

  1. Application of queueing theory to pharmacokinetics.

    PubMed

    Brill, P H; Moon, R E

    1980-05-01

    This paper considers the steady-state plasma drug concentration in a one-compartment, open pharmacokinetic model with multiple doses and first-order kinetics using a classical deterministic technique as well as a queueing theoretical stochastic analysis. The stochastic analysis employs a new method for obtaining the steady-state probability distribution of the content of a dam with compound Poisson input and a general release rule. It is shown that if the deterministic steady-state average concentration exists, it is equal to the mean value of the steady-state concentration, the probability distribution of which is obtained using the stochastic model. Moreover, the steady-state probability distribution of the concentration and its mean always exist in the stochastic model. Ramifications of the stochastic method of analysis are discussed.

  2. 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)

  3. 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.

  4. How to Computerize School Bus Scheduling.

    ERIC Educational Resources Information Center

    Creighton, Roger L.

    1986-01-01

    School systems will soon be using microcomputers to design their school bus routes and aid in the management of transportation programs. Offers guidelines to bring microcomputer bus management to school systems. (MLF)

  5. 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

  6. 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.

  7. 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

  8. Multi-purpose satellite bus

    NASA Technical Reports Server (NTRS)

    Sakoda, Daniel; Agrawal, Brij N.

    1991-01-01

    The Multi-Purpose Satellite bus (MPS) can be used for a number of payloads which may require different orbits, pointing accuracy, and electrical power consumption. Specifically, it was designed to accommodate the Advanced Very High Resolution Radiometer and an EHF communication payload, both of which have a three-year life. The estimated beginning-of-life weight of the MPS bus is 150 kg. It can be launched by either the Pegasus ALV or the Taurus SSLV. Configuration requirements for the different missions are discussed.

  9. 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.

  10. School Bus Alert System Reduces Delays.

    ERIC Educational Resources Information Center

    Pleasnick, Stephen G.

    1985-01-01

    The school bus alert monitor is a computerized school bus alert and warning sytem that notifies parents of school bus arrival via radio frequency technology. The system also has been shown to enhance the self esteem of disabled transportation users. (CL)

  11. How To Decrease School Bus Vandalism.

    ERIC Educational Resources Information Center

    Saddlemire, Richard

    1990-01-01

    Suggestions for principals to decrease school bus vandalism are presented. Guidelines are offered for the improvement of bus conditions, reorganization of the transportation system, establishment of a bus driver training program, and student involvement in an antivandalism campaign. Cooperation and regular meetings between students, parents,…

  12. Data Bus Adapts to Changing Traffic Level

    NASA Technical Reports Server (NTRS)

    Lew, Eugene; Deruiter, John; Varga, Mike

    1987-01-01

    Access becomes timed when collisions threaten. Two-mode scheme used to grant terminals access to data bus. Causes bus to alternate between random accessibility and controlled accessibility to optimize performance and adapt to changing data-traffic conditions. Bus is part of 100-Mb/s optical-fiber packet data system.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Synchronizing Data-Bus Messages

    NASA Technical Reports Server (NTRS)

    Harris, L. H.

    1985-01-01

    Adapter allows communications among as many as 30 data processors without central bus controller. Adapter improves reliability of multiprocessor system by eliminating point of failure that causes entire system to fail. Scheme prevents data collisions and eliminates nonessential polling, thereby reducing power consumption.

  20. 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).

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Bus/rail interface design guideline manual

    SciTech Connect

    Not Available

    1988-10-01

    The document provides a guide for the design and placement of bus-related facilities and amenities when integrated with rail operation. It presents criteria for station location and delineates functions to be provided for bus/rail interface stations. Rationale for revising existing bus routes to serve rail stations is also presented and types of amenities to be furnished along with rationale that justify provision are discussed. Design criteria that indicate minimum specifications for acceptable operations are included.

  8. Standard NIM digital bus (NIM/GPIE)

    NASA Astrophysics Data System (ADS)

    1983-08-01

    A standard digital data bus for nuclear instrument module (NIM) instruments as defined in DOE Publication TID-20893 utilizes the General Purpose Instrumentation Bus (GPIB) of ANSI/IEEE Std 488-1978 and the Code and Format conventions of ANSI/IEEE Std 728-1982 of the Institute of Electrical and Electronics Engineers (IEEE) and the American National Standards Institute (ANSI). Additional requirements and recommendations are included to maximize compatibility of NIM instruments utilizing the bus.

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. 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…

  14. Neurosimulation modeling of a scheduled bus route

    SciTech Connect

    Lee, S.G.; Khoo, L.P.

    1997-05-01

    In a densely built-up urban society, operators of public bus services are faced with the recurrent problem of providing timely and reliable service. Wile they have no control over dynamically changing extraneous factors (such as passenger loads or road conditions) that may suddenly degrade the quality of the service provided, it is nonetheless desirable for management to study the extent to which these factors affect their business, and what measures, if any, can be adopted to neutralize them. This paper discusses how a simulation model of a bus route, embellished by a neural network, was created to model the historical pattern of the inputs (namely, passenger loads and road conditions) that affect the overall scheduled terminus-to-terminus time. Thus, in a case study of a bus route running from a suburb to the city center, it was found that the neurosimulation model could predict the cumulative terminus-to-terminus times better than a conventional simulation model could. A software module, embedded into the neurosimulation model for the purposes of speed regulation, was able to minimize the deviation of the bus service from schedule. When intentional delays were further introduced into the bus route, it was discovered that the speed regulator was more effective the longer the delay, and the further the bus traveled into the bus route. There is potential in applying neural computing in a dynamic bus scheduling problem such as the one discussed here.

  15. School Bus Driver Instructional Program. Instructor's Guide.

    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 needed by the school bus driver instructor, as well as those supplemental skills and knowledge…

  16. Who's Driving This Bus Anyway? Empowering Drivers.

    ERIC Educational Resources Information Center

    Allen, J. D.

    1997-01-01

    In 1977, a school transportation director developed a policy giving school bus drivers authority to discipline unruly student behavior via a system of graduated warnings and suspension of riding privileges. Most parents have been supportive and expect their kids to behave on the bus. In the interest of safety, school administrators should support…

  17. California's Bus Driver's Training Course. Instructor's Manual.

    ERIC Educational Resources Information Center

    California State Dept. of Education, Sacramento.

    This instructor's manual was designed to help graduates of the California Bus Driver Instructor Course provide effective instruction to school bus driver trainees. It contains enough material for 20-30 hours of classroom training. The information is organized in 12 instructional units that cover the following topics: introduction to the course;…

  18. School Bus Maintenance. Bulletin, 1948, No. 2

    ERIC Educational Resources Information Center

    Featherston, E. Glenn

    1948-01-01

    This bulletin is one in the series on pupil transportation issued by the Office of Education. Its purpose is to furnish information and guidance for local school administrators and others who are concerned with school bus maintenance. Programs of school bus maintenance vary among the 48 States. Presumably all contract vehicles are maintained by…

  19. 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…

  20. 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.

  1. 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.

  2. 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.

  3. High speed bus technology development

    NASA Astrophysics Data System (ADS)

    Modrow, Marlan B.; Hatfield, Donald W.

    1989-09-01

    The development and demonstration of the High Speed Data Bus system, a 50 Million bits per second (Mbps) local data network intended for avionics applications in advanced military aircraft is described. The Advanced System Avionics (ASA)/PAVE PILLAR program provided the avionics architecture concept and basic requirements. Designs for wire and fiber optic media were produced and hardware demonstrations were performed. An efficient, robust token-passing protocol was developed and partially demonstrated. The requirements specifications, the trade-offs made, and the resulting designs for both a coaxial wire media system and a fiber optics design are examined. Also, the development of a message-oriented media access protocol is described, from requirements definition through analysis, simulation and experimentation. Finally, the testing and demonstrations conducted on the breadboard and brassboard hardware is presented.

  4. Prevalence of hypertension in bus drivers.

    PubMed

    Ragland, D R; Winkleby, M A; Schwalbe, J; Holman, B L; Morse, L; Syme, S L; Fisher, J M

    1987-06-01

    This paper reports the results of a cross-sectional study conducted to evaluate the prevalence of hypertension in 1500 black and white male bus drivers from a large urban transit system in the US. Data for this study were compiled from the files of an occupational health clinic which conducts biennial medical examinations for drivers' license renewal. To test whether prevalence of hypertension was higher among bus drivers than among employed individuals in general, drivers were compared to three groups: individuals from both a national and local health survey and individuals undergoing baseline health examinations prior to employment as bus drivers. After adjustment for age and race, hypertension rates for bus drivers were significantly greater than rates for each of the three comparison groups. These findings support previous results from international studies of bus drivers suggesting that exposure to the occupation of driving a bus may carry increased health risk. This research has expanded into an on-going study which has the goals of clarifying the extent of hypertension in bus drivers and identifying specific behavioural and occupational factors that may be responsible for increased risk of cardiovascular disease.

  5. 49 CFR 605.19 - Approval of school bus operations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... school bus operations. (a) The Administrator will consider the comments filed by private school bus... the administrator to private school bus operators required to be notified under § 605.16. (e) Private school bus operators who receive notice under paragraph (d) of this section may within 20 days...

  6. 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... REGULATIONS WAKE ISLAND CODE Motor Vehicle Code § 935.138 Motor bus operation. Each person operating a motor bus on Wake Island shall— (a) Keep its doors closed while the bus is moving with passengers on...

  7. 49 CFR 605.19 - Approval of school bus operations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 7 2011-10-01 2011-10-01 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...

  8. 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... REGULATIONS WAKE ISLAND CODE Motor Vehicle Code § 935.138 Motor bus operation. Each person operating a motor bus on Wake Island shall— (a) Keep its doors closed while the bus is moving with passengers on...

  9. Resource Selection Using Execution and Queue Wait Time Predictions

    NASA Technical Reports Server (NTRS)

    Warren, Smith; 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.

  10. 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.

  11. 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.

  12. Effect of speedup delay on shuttle bus schedule

    NASA Astrophysics Data System (ADS)

    Nagatani, Takashi

    2016-10-01

    We study the bus schedule in the shuttle bus transportation system controlled by speedup. The bus schedule is closely related to the dynamic motion of the bus. The motion of a shuttle bus depends on the inflow rate of passengers and the delayed speedup control. The delayed speedup control has an important effect on the dynamic motion of the bus. We present the delayed map model for the dynamics of the shuttle bus with the delayed speedup control. The bus motion changes from a stable state, through a periodic state, to a quasi-periodic state by the delayed speedup control. The return map of the tour time displays a smooth closed curve and the bus motion is quasi-periodic. The dynamic transition to the quasi-periodic motion changes greatly with the delay time. We clarify the effect of the delayed speedup control on the bus schedule.

  13. Virtual queueing techniques for UBR+ service in ATM with fair access and minimum bandwidth guarantee

    SciTech Connect

    Siu, K.Y.; Wu, Y.; Ren, W.

    1998-11-01

    The ATM Forum is currently discussing the need for a new best-effort service called UBR+, which is an enhancement to the existing UBR service, to support data traffic. The objective of the UBR+ service is to provide each user with a minimum service rate guarantee and a fair access to any excess available bandwidth. In this paper, the authors present a new efficient scheme for supporting this service. The key advantage of the scheme is that it employs only FIFO queueing (instead of per-VC queueing) and admits simple implementation in ATM switches. The ideas involve a simple scheduling mechanism that is based on per-VC queueing and incorporate the virtual queueing technique that can efficiently emulate per-VC queueing on a shared FIFO queue. Simulation results are presented to show that the schemes can deliver almost ideal performance for supporting the new service requirements of UBR+.

  14. 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.

  15. 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.

  16. 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.

  17. Computerized Bus Routing in San Francisco.

    ERIC Educational Resources Information Center

    Caswell, Peter J.; Jungherr, J. Anton

    1979-01-01

    A computerized routing and scheduling system for the San Francisco Public Schools includes the batch processing of bus route assignments and schedules for all schools and the online terminal processing of daily changes. (Author/MLF)

  18. The high speed bus technology development program

    NASA Astrophysics Data System (ADS)

    Ludvigson, M. T.; Modrow, M. B.; Goldman, P. C.

    The current development status of a high-speed data bus to link MIL-STD-1750A computers in avionics applications is reviewed and illustrated with diagrams and photographs. The bus requirements include data rate 50 Mb/s, a linear token-passing scheme permitting both electronic and fiber-optic implementation, up to 64-terminal capacity, maximum terminal separation 300 ft, latency control via token-rotation-timer priority, self-test and bus-loop test capability, and automatic clock synchronization. The design concept and performance of a breadboard wire bus tested in July 1986 are discussed in detail, with particular attention to the redundancy manager, the output controller, the input controller, the ringmaster topology manager, and typical initial-placement problems.

  19. 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.

  20. 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.

  1. 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.

  2. 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…

  3. 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

  4. 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…

  5. Bullying and Aggression on the School Bus: School Bus Drivers' Observations and Suggestions

    ERIC Educational Resources Information Center

    deLara, Ellen

    2008-01-01

    Every school day bus drivers are responsible for transporting children safely over many miles, yet they are rarely polled for their opinions or contributions to school safety. School bus drivers are in a unique position to inform the discussion on aggressive behavior during the school day. This exploratory study collected information from school…

  6. 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.

  7. 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.

  8. 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.

  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. Analysis of performance measures with single channel fuzzy queues under two class by using ranking method

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    In this paper, we propose a procedure to find different performance measurements under crisp value terms for new single fuzzy queue FM/F(H1,H2)/1 with two classes, where arrival rate and service rates are all fuzzy numbers which are represented by triangular and trapezoidal fuzzy numbers. The basic idea is to obtain exact crisp values from the fuzzy value, which is more realistic in the practical queueing system. This is done by adopting left and right ranking method to remove the fuzziness before computing the performance measurements using conventional queueing theory. The main advantage of this approach is its simplicity in application, giving exact real data around fuzzy values. This approach can also be used in all types of queueing systems by taking two types of symmetrical linear membership functions. Numerical illustration is solved in this article to obtain two groups of crisp values in the queueing system under consideration.

  11. The health bus: healthcare for marginalized populations.

    PubMed

    Daiski, Isolde

    2005-02-01

    The Health Bus, an innovative outreach program, serves the marginalized population of a large Canadian city. In this article, a needs assessment/evaluation study of its services is discussed. Barriers to mainstream healthcare and solutions are examined. This study was qualitative, descriptive, and exploratory and surveyed 58 client volunteers of the program through semistructured interviews and focus groups. Thematic analysis of data was carried out. The Health Bus was found to provide basic healthcare and supplies effectively. Clients value respectful treatment, competency of healthcare professionals, and accessibility, whereas disrespectful treatments and lack of transportation are barriers to mainstream healthcare. A conclusion of this study is that Health Bus services should be expanded with clients' input. Mainstream institutions need flexibility and a change in attitudes toward the marginalized.

  12. High speed data bus design validation

    NASA Astrophysics Data System (ADS)

    Stevens, Rick

    The SAE Linear Implementation Task Group has developed the SAE Linear Token Passing Multiplex Data Bus Standard (AS4074.1) and is currently working on a validation plan. This validation plan will define the test requirements for determining that an implementation of the standard meets the requirements of SAE AS4074.1. Once completed, the test requirements contained in this plan will be executed on bus interface units (BIUs) for validation purposes. In the present work, the author describes the use of a validation model that incorporates many of the capabilities of the validation test plan. This model can also be thought of as a VHDL (VHSIC Hardware Description Language) behavioral representation of the SAE Linear Token Passing Multiplex Data Bus Standard. It is tightly coupled to the standard and provides a model that can be used during the BIU development to validate the design.

  13. ORION II bus demonstration. Demonstration report (Final)

    SciTech Connect

    Shanley, J.

    1989-02-01

    The Central New York Regional Transportation Authority conducted an 18-month demonstration to determine how the ORION II bus operates in actual service. The ORION II vehicle is a small low floor, accessible heavy duty, diesel-powered transit bus designed to meet the needs of the elderly and handicapped. It has the capacity to seat 26 passengers with 4 wheelchair lockdowns. Side and rear doors are equipped with electrically powered ramps. Eight Thomas vehicles (22-foot, 11,500 lbs, wheelchair equipped, gasoline fueled) were also tested during the demonstration period. Operations (fuel and oil usage) and maintenance (scheduled and unscheduled) data were collected and charted-out in the report as well as driver, passenger, and maintenance surveys. This report provides descriptions, photographs, and comparison charts of both the diesel-fueled ORION II transit bus and the gasoline-fueled Thomas vehicles along with the demonstration test plan, evaluations, conclusions, and survey results.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. Research in bus and rail transit operations

    SciTech Connect

    Chatterjee, A.; Wegmann, F.J.; Ceder, A.; Levinson, H.S.; Hollander, A.

    1989-01-01

    The 10 papers in the report deal with the following areas: Private Sector Involvement in Sponsoring Sunday Bus Service; Optimal Design of Transit Short-Turn Trips; New York City's Unfranchised Buses: Case Study in Deregulation; Critical Factors in Planning Multimodal Passenger Terminals; Use of Travelers' Attitudes in Rail Service Design; Driven, Attended, and Fully Automated Transit; Qualitative Comparison; Impact on Transit Patronage of Cessation or Inauguration of Rail Service; Use of Productivity Factors in Estimating LRT Operating Costs; Simulation Study To Evaluate Spare Ratios in Bus Transit Systems; Statistical Evaluation of Spare Ratio in Transit Rolling Stock.

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

    PubMed Central

    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

  20. 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.

  1. Chimpanzee females queue but males compete for social status

    PubMed Central

    Foerster, Steffen; Franz, Mathias; Murray, Carson M.; Gilby, Ian C.; Feldblum, Joseph T.; Walker, Kara K.; Pusey, Anne E.

    2016-01-01

    Dominance hierarchies are widespread in animal social groups and often have measureable effects on individual health and reproductive success. Dominance ranks are not static individual attributes, however, but instead are influenced by two independent processes: 1) changes in hierarchy membership and 2) successful challenges of higher-ranking individuals. Understanding which of these processes dominates the dynamics of rank trajectories can provide insights into fitness benefits of within-sex competition. This question has yet to be examined systematically in a wide range of taxa due to the scarcity of long-term data and a lack of appropriate methodologies for distinguishing between alternative causes of rank changes over time. Here, we expand on recent work and develop a new likelihood-based Elo rating method that facilitates the systematic assessment of rank dynamics in animal social groups, even when interaction data are sparse. We apply this method to characterize long-term rank trajectories in wild eastern chimpanzees (Pan troglodytes schweinfurthii) and find remarkable sex differences in rank dynamics, indicating that females queue for social status while males actively challenge each other to rise in rank. Further, our results suggest that natal females obtain a head start in the rank queue if they avoid dispersal, with potential fitness benefits. PMID:27739527

  2. 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.

  3. 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.

  4. 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.

  5. Developing a Computer Program for Bus Routing. Final Report.

    ERIC Educational Resources Information Center

    Newton, Rita M.; Thomas, Warren H.

    A computer-based method was developed that can translate available data about schools, students, and bus facilities into a set of bus routes and schedules prior to the start of the school year. Each route can be so designed via the computer model that student riding time and bus capacity constraints are satisfied at the same time that total bus…

  6. 49 CFR 374.317 - Identification-bus and driver.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Identification-bus and driver. 374.317 Section 374.317 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL MOTOR CARRIER...—bus and driver. Each bus and driver providing service shall be identified in a manner visible...

  7. 49 CFR 374.317 - Identification-bus and driver.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 5 2011-10-01 2011-10-01 false Identification-bus and driver. 374.317 Section 374.317 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL MOTOR CARRIER...—bus and driver. Each bus and driver providing service shall be identified in a manner visible...

  8. 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)

  9. 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…

  10. Inrush-Current Limiter And Bus Isolator

    NASA Technical Reports Server (NTRS)

    Dolland, Carlisle R.

    1994-01-01

    Electronic circuit protects electrical power bus and source of power against excessive current demands. Circuit intended for use with power-consuming electronic system drawing pulsed currents and including capacitor bank as low-impedance secondary source from which pulsed currents drawn.

  11. 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.

  12. 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.

  13. 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...

  14. Repeater For A Digital-Communication Bus

    NASA Technical Reports Server (NTRS)

    Torres-Guzman, Esteban; Olson, Stephen; Heaps, Tim

    1993-01-01

    Digital repeater circuit designed to extend range of communication on MIL-STD-1553 bus beyond original maximum allowable length of 300 ft. Circuit provides two-way communication, one way at time, and conforms to specifications of MIL-STD-1553. Crosstalk and instability eliminated.

  15. 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.

  16. 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.

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

    PubMed

    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.

  18. 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.

  19. 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.

  20. Priorities for an age-friendly bus system.

    PubMed

    Broome, Kieran; Worrall, Linda; McKenna, Kryss; Boldy, Duncan

    2010-09-01

    This article presents the results of a study on the barriers and facilitators to bus use for people aged 60 or older. Two complementary methodologies, nominal group technique and focussed ethnography, were used to identify barriers and facilitators and rank their importance. Two sample sites from Queensland, Australia, were selected, with 227 people participating in the nominal group technique and 40 people participating in the focussed ethnography component. Seven priorities for age-friendly bus systems emerged from the data: vehicle entrance/exit; bus driver friendliness and helpfulness; timetables and scheduling of buses; bus stop locations; pedestrian infrastructure; information and training for older people; and bus routes and destinations. These findings will assist researchers, policy makers, and transport providers to set evidence-based strategic directions for creating age-friendly bus systems. Both methods provide complementary perspectives on bus usability, which could not be gained from either method alone.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

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

    PubMed

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

    1991-08-28

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

  7. Repairable queue with non-exponential service time and variable breakdown rates

    NASA Astrophysics Data System (ADS)

    Khew, Koh Siew; Hin, Pooi Ah; Fei, Tan Yi

    2015-05-01

    Consider a single server queue in which the service station may breakdown according to a Poisson process with rates γ in busy time and γ' in idle time respectively. After a breakdown, the service station will be repaired immediately and the repair time is assumed to have an exponential distribution with rate δ. Suppose the arrival time has an exponential distribution with rate λ, and the probability density function g(t) and the cumulative distribution function G(t) of the service time are such that the rate g(t)/[1 - G(t)] tends to a constant as t tends to infinity. When the queue is in a stationary state, we derive a set of equations for the probabilities of the queue length and the states of the arrival and service processes. Solving the equations, we obtain approximate results for the stationary probabilities which can be used to obtain the stationary queue length distribution of the system.

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

    SciTech Connect

    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.

  9. 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.

  10. CAN Bus on ExoMars

    NASA Astrophysics Data System (ADS)

    Tortosa López, F.; Furano, G.; Winton, A.; Montagna, M.; Caramia, M.; Dean, B.; Bhana, M.

    2009-05-01

    This paper focuses on the implementation of CAN Bus for the EXOMars project, both on the technical aspects of the physical layer, the CAN protocol, and the higher layer protocol, and on the methodology aspects related to the procurement of multiple heterogeneous units, which need to provide a standard interface to the CAN Bus. We will present the ExoMars tailoring and technical choices using the current draft of the CAN ECSS-E50- xx-v2_1 ([5]), and we will present our conclusions regarding the use of CANopen and the draft standard. The Exomars project has successfully applied the previous efforts of CAN WG, and has established a clear implementation methodology that will provide very useful inputs for the finalization of the ECSS standardization process within next year.

  11. Approximations in the performance evaluation of queueing systems. Final technical report

    SciTech Connect

    Knessl, Charles; Tier, Charles

    2001-06-06

    The research program on this grant was to develop new asymptotic and perturbation methods for approximating the performance of queueing systems. This involved obtaining approximations to complicated equations.The approximations provide accurate formulas for the performance measures. Queueing models of these types arise in the analysis of computer and communications systems such as ATM networks. In addition, the methods developed in the proposal were also found to be applicable to other stochastic and diffusion models.

  12. Simulation Model of Bus Rapid Transit

    NASA Astrophysics Data System (ADS)

    Gunawan, Fergyanto E.; Suharjito; Gunawan, Alexander A. S.

    2014-03-01

    Bus rapid transit system is modern solution for mass transportation system. The system, in comparison to the rail-based transportation system, is significantly cheaper and requires shorter development time, but lower performance. The BRT system performance strongly depends on variables related to station design and infrastructure. A numerical model offers an effective and efficient means to evaluate the system performance. This article offers a detailed numerical model on the basis of the discrete-event approach and demonstrates its application.

  13. Evolution of weighted complex bus transit networks with flow

    NASA Astrophysics Data System (ADS)

    Huang, Ailing; Xiong, Jie; Shen, Jinsheng; Guan, Wei

    2016-02-01

    Study on the intrinsic properties and evolutional mechanism of urban public transit networks (PTNs) has great significance for transit planning and control, particularly considering passengers’ dynamic behaviors. This paper presents an empirical analysis for exploring the complex properties of Beijing’s weighted bus transit network (BTN) based on passenger flow in L-space, and proposes a bi-level evolution model to simulate the development of transit routes from the view of complex network. The model is an iterative process that is driven by passengers’ travel demands and dual-controlled interest mechanism, which is composed of passengers’ spatio-temporal requirements and cost constraint of transit agencies. Also, the flow’s dynamic behaviors, including the evolutions of travel demand, sectional flow attracted by a new link and flow perturbation triggered in nearby routes, are taken into consideration in the evolutional process. We present the numerical experiment to validate the model, where the main parameters are estimated by using distribution functions that are deduced from real-world data. The results obtained have proven that our model can generate a BTN with complex properties, such as the scale-free behavior or small-world phenomenon, which shows an agreement with our empirical results. Our study’s results can be exploited to optimize the real BTN’s structure and improve the network’s robustness.

  14. 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.

  15. 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.

  16. 49 CFR 605.18 - Comments by private school bus operators.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 7 2011-10-01 2011-10-01 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...

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. Reliable Fiber Sensor System with Star-Ring-Bus Architecture

    PubMed Central

    Peng, Peng-Chun; Wang, Jun-Bo; Huang, Kuan-Yan

    2010-01-01

    This work presents a novel star-ring-bus sensor system and demonstrates its effectiveness. The main trunk of the proposed sensor system is a star topology and the sensing branches comprise a series of bus subnets. Any weakness in the reliability of the sensor system is overcome by adding remote nodes and switches to the ring and bus subnets. To construct the proposed star-ring-bus sensor system, a fiber ring laser scheme is used to improve the signal-to-noise ratio of the sensor system. The proposed system increases the reliability and capacity of fiber sensor systems. PMID:22399876

  2. Reliable fiber sensor system with star-ring-bus architecture.

    PubMed

    Peng, Peng-Chun; Wang, Jun-Bo; Huang, Kuan-Yan

    2010-01-01

    This work presents a novel star-ring-bus sensor system and demonstrates its effectiveness. The main trunk of the proposed sensor system is a star topology and the sensing branches comprise a series of bus subnets. Any weakness in the reliability of the sensor system is overcome by adding remote nodes and switches to the ring and bus subnets. To construct the proposed star-ring-bus sensor system, a fiber ring laser scheme is used to improve the signal-to-noise ratio of the sensor system. The proposed system increases the reliability and capacity of fiber sensor systems.

  3. 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.

  4. Quantum-information processing via a lossy bus

    SciTech Connect

    Barrett, S. D.; Milburn, G. J.

    2006-12-15

    We describe a method to perform two-qubit measurements and logic operations on pairs of qubits which each interact with a harmonic oscillator degree of freedom (the bus), but do not directly interact with one another. Our scheme uses only weak interactions between the qubit and the bus, homodyne measurements, and single-qubit operations. In contrast to earlier schemes, the technique presented here is extremely robust to photon loss in the bus mode, and can function with high fidelity even when the rate of photon loss is comparable to the strength of the qubit-bus coupling.

  5. Stability and performance of ant queue inspired task partitioning methods.

    PubMed

    Scheidler, Alexander; Merkle, Daniel; Middendorf, Martin

    2008-06-01

    In this paper, we consider computing systems that have autonomous helper components which fulfill support functions and that possess reconfigurable hardware so that they can specialize to different types of service tasks. Several self-organized task partitioning methods are proposed that can be used by the helper components to decide how to reconfigure and which service tasks to execute. The proposed task partitioning methods are inspired by the so-called ant queue system that can be found in real ants for partitioning tasks between the individuals. The aim of this study is to investigate basic properties of the task partitioning methods, like stability and efficiency, in order to obtain basic insights into the design of task partitioning methods in self-organized service systems. More precisely, the investigations are threefold: (1) discrete event simulations are used to investigate systems, (2) for a simple version of the task partitioning system analytical stability results are obtained by means of delay differential equation systems and (3) by numerically solving initial value problems.

  6. 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.

  7. Folding Proteins at 500 ns/hour with Work Queue

    PubMed Central

    Abdul-Wahid, Badi’; Yu, Li; Rajan, Dinesh; Feng, Haoyun; Darve, Eric; Thain, Douglas; Izaguirre, Jesús A.

    2014-01-01

    Molecular modeling is a field that traditionally has large computational costs. Until recently, most simulation techniques relied on long trajectories, which inherently have poor scalability. A new class of methods is proposed that requires only a large number of short calculations, and for which minimal communication between computer nodes is required. We considered one of the more accurate variants called Accelerated Weighted Ensemble Dynamics (AWE) and for which distributed computing can be made efficient. We implemented AWE using the Work Queue framework for task management and applied it to an all atom protein model (Fip35 WW domain). We can run with excellent scalability by simultaneously utilizing heterogeneous resources from multiple computing platforms such as clouds (Amazon EC2, Microsoft Azure), dedicated clusters, grids, on multiple architectures (CPU/GPU, 32/64bit), and in a dynamic environment in which processes are regularly added or removed from the pool. This has allowed us to achieve an aggregate sampling rate of over 500 ns/hour. As a comparison, a single process typically achieves 0.1 ns/hour. PMID:25540799

  8. When the Wheels on the Bus Go Round: Social Interactions on the School Bus

    ERIC Educational Resources Information Center

    Galliger, Courtney C.; Tisak, Marie S.; Tisak, John

    2009-01-01

    Children's social interactions are often dependent upon the setting or context in which they occur. The current study explored the school bus as a unique context for social interaction. One hundred and fifty-seven elementary school students (78 males and 79 females), in grades 3, 4, and 5, completed a questionnaire concerning the rate and types of…

  9. 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…

  10. 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

  11. 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.

  12. 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).

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

    PubMed

    Joy, Mark; Jones, Simon

    2005-08-01

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

  14. A parametric programming solution to the F-policy queue with fuzzy parameters

    NASA Astrophysics Data System (ADS)

    Yang, Dong-Yuh; Chang, Po-Kai

    2015-03-01

    This paper investigates the F-policy queue using fuzzy parameters, in which the arrival rate, service rate, and start-up rate are all fuzzy numbers. The F-policy deals with the control of arrivals in a queueing system, in which the server requires a start-up time before allowing customers to enter. A crisp F-policy queueing system generalised to a fuzzy environment would be widely applicable; therefore, we apply the α-cuts approach and Zadeh's extension principle to transform fuzzy F-policy queues into a family of crisp F-policy queues. This study presents a mathematical programming approach applicable to the construction of membership functions for the expected number of customers in the system. Furthermore, we propose an efficient solution procedure to compute the membership function of the expected number of customers in the system under different levels of α. Finally, we give an example of the proposed system as applied to a case in the automotive industry to demonstrate its practicality.

  15. 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.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

    Khoshnevisan, Ladan; Salmasi, Farzad R.

    2016-05-01

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

  18. Integration of queueing networks and Generalized Stochastic Petri Nets for the performance evaluation of computer systems

    SciTech Connect

    Ghanta, S.

    1985-01-01

    This thesis addresses the issue of being able to efficiently solve large, complex computer system models by means of a unified technique that employs a combination of product-form queueing networks and Generalized Stochastic Petri Nets. An algorithm is developed for the solution of homogeneous queueing networks with many processors and many classes. Because of the exponential complexity in terms of the number of classes for the general-purpose algorithms like Mean Value Analysis, medium to large-sized networks are beyond tractability. A particular class of queueing network is identified that is suitable for modeling local area networks; then a polynomial algorithm is developed for the solution of this category of networks that exploits the inherent symmetry of these networks. The author then describes the central ideas behind a new modeling technique that combines the best features of product form queueing networks and Generalized Stochastic Petri Nets. He explains how this technique is related to many other existing techniques. This technique has the following features: (1) a representational power and/or flexibility comparable to that of Generalized Stochastic Petri Nets: (2) an accuracy comparable to that found when using a complete set of global balance equations for the system model; and (3) an efficiency comparable to that of product-form queueing networks.

  19. 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…

  20. Parents' Perceptions of the Rural School Bus Ride

    ERIC Educational Resources Information Center

    Ramage, Rob; Howley, Aimee

    2005-01-01

    This article reports findings from a study of the perceptions of parents about the experience of long bus rides on their children. Twenty-six parents, whose homes were located on the longest bus route in a rural Midwestern school district, provided interviews regarding the experiences of a total of 37 students. In the analysis of the interview…

  1. 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...

  2. 32 CFR 935.138 - Motor bus operation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 6 2013-07-01 2013-07-01 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...

  3. 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...

  4. 45 CFR 1310.17 - Driver and bus monitor training.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 4 2014-10-01 2014-10-01 false Driver and bus monitor training. 1310.17 Section... START PROGRAM HEAD START TRANSPORTATION Transportation Requirements § 1310.17 Driver and bus monitor... records as necessary. (c) Drivers must also receive instruction on the topics listed in 45 CFR...

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. 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…

  10. 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.

  11. 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.

  12. 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.

  13. Regenerative polymeric bus architecture for board-level optical interconnects.

    PubMed

    Bamiedakis, N; Hashim, A; Penty, R V; White, I H

    2012-05-21

    A scalable multi-channel optical regenerative bus architecture based on the use of polymer waveguides is presented for the first time. The architecture offers high-speed interconnection between electrical cards allowing regenerative bus extension with multiple segments and therefore connection of an arbitrary number of cards onto the bus. In a proof-of-principle demonstration, a 4-channel 3-card polymeric bus module is designed and fabricated on standard FR4 substrates. Low insertion losses (≤ -15 dB) and low crosstalk values (< -30 dB) are achieved for the fabricated samples while better than ± 6 µm -1 dB alignment tolerances are obtained. 10 Gb/s data communication with a bit-error-rate (BER) lower than 10(-12) is demonstrated for the first time between card interfaces on two different bus modules using a prototype 3R regenerator.

  14. 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

  15. 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.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. The wheels on the bus go "buy buy buy": school bus advertising laws.

    PubMed

    Pomeranz, Jennifer L

    2012-09-01

    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.

  3. 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.

  4. The wheels on the bus go "buy buy buy": school bus advertising laws.

    PubMed

    Pomeranz, Jennifer L

    2012-09-01

    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

  5. 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.

  6. 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

  7. Classroom Activities in School Bus and Pedestrian Safety Education. Bulletin No. 93138.

    ERIC Educational Resources Information Center

    Wisconsin State Dept. of Transportation, Madison.

    School bus and related pedestrian safety education is prevention-oriented so that students will learn how to avoid bus-related accidents. This manual provides lesson plans emphasizing the school bus stop, loading and unloading zones, emergency evacuation drills, and appropriate behavior on the school bus. The guide also recognizes demographic…

  8. 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.

  9. 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.

  10. 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.

  11. Queueing Delay and Energy Efficiency Analyses of Sleep Based Power Saving Mechanism

    NASA Astrophysics Data System (ADS)

    Zhu, Fan; Wu, Yiqun; Niu, Zhisheng

    In wireless networks, sleep mode based power saving mechanisms can reduce the energy consumption at the expense of additional packet delay. This letter analyzes its packet queueing delay and wireless terminals' energy efficiency. Based on the analysis, optimal sleep window size can be derived to optimize terminal energy efficiency with delay constraint.

  12. 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.

  13. 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…

  14. 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.

  15. 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…

  16. 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

  17. 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.

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

    DOE PAGES

    Dechev, Damian; Zhang, Deli

    2015-04-03

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  20. 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

  1. 234. Dennis Hill, Photographer July 1998 VIEW OF BUS STOP, ...

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

    234. Dennis Hill, Photographer July 1998 VIEW OF BUS STOP, UPPER DECK OF YERBA BUENA EAST VIADUCT, FACING WEST. - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

  2. 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.

  3. State Bus Fleet Study Documents Fuel-Saving Measures.

    ERIC Educational Resources Information Center

    Collings, Amy

    1990-01-01

    A demonstration program conducted in 12 New Jersey school districts identified 18 fuel cost-saving opportunities for school bus operation that could save the state an estimated $1.6 million in fuel costs. (MLF)

  4. 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.

  5. These New Devices Aim to Enhance School Bus Safety.

    ERIC Educational Resources Information Center

    Stover, Del

    1988-01-01

    Describes school bus safety products currently on the market, such as motion-sensing alarms, automatic breaking shields, front-mounted crossing gates, and strobe lights. Gives price information and evaluates products' usefulness and necessity. (MLH)

  6. Study on USB Based CAN Bus for Data Measurement System

    NASA Astrophysics Data System (ADS)

    Wu, Weibin; Hong, Tiansheng; Zhu, Yuqing; He, Guangbin; Ye, Cheng; Li, Haobiao; Chen, Chuwen

    Control area network (CAN) is an international protocol of field bus and universal serial bus (USB) is developing more and more widely. On the other hand, the USB technology combined with the CAN application is still in the development stage, so this research has broad prospects. The USB-based CAN bus system hardware consists of a CAN module, a USB communication module and a micro controller. It has been designed for real-time display and can save the CAN bus message. In addition it has been debugged in actual measurement accompanied by the Kvaser USB CAN II. The test results show that the system can correctly receive all messages frame from Kvaser CanKing. Finally the system has been applied to the project of citrus orchard for transmission of data of the citrus and tree parameters.

  7. 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

  8. 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.

  9. 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.

  10. Effect of passenger position on fear of danger experienced during sudden bus stops.

    PubMed

    Aoki, Takeo; Uetake, Teruo; Shimoda, Masahiro

    2009-06-01

    The purpose of this study was to identify the effect of bus passengers' positions on their fear of danger when a bus stopped suddenly. A temporary bus running course with one bus stop was set up on the campus of the Tokyo University of Agriculture and Technology (TUAT). The bus ran the course 14 times with the bus stopping twice during the course, once at the bus stop and again just after re-starting from the bus stop. The driver was asked to brake more strongly than usual when stopping. Sixteen students (15 males and 1 female) between the ages of 18 and 21 years participated. In turn, all participants were asked to take 14 different postures in the bus. Participants were also asked to report their level of fear on a rating scale each time the bus stopped. The study showed that (1) passengers' fear of danger at the first sudden stop was typically higher than that at the second stop, (2) standing passengers who held hand straps experienced more fear than those who held fixed safety devices, (3) bus passengers sitting on the centre of the rear seat had a great risk of injury if the bus stopped suddenly, and (4) when passengers faced the window and stood transversely with respect to from the moving direction of the bus and the bus stopped suddenly, passengers' fear of danger was affected by the side of the bus on which they stood as well as which hand they used to grasp a safety device.

  11. Multipurpose bus interface utilizing a digital signal processor

    NASA Astrophysics Data System (ADS)

    Houlberg, Christian L.

    1994-09-01

    A multi-purpose bus interface comprising a digital signal processor which receives a clock signal and control signals from a Manchester type encoder/decoder and then processes the clock and control signals allowing for the serial transfer of data to and from the 1553 multiplex data bus, the encoder/decoder and the digital signal processor into an IC memory card for storage in or retrieval from the IC memory card. Software stored in an electrically erasable programmable read only memory controls how the data is transferred and interpreted making it easier to modify the digital signal processor's operation to accommodate its use with different bus standards and data protocols/formats. The encoder/decoder of the present invention formats and protocols data transferred from the electrically erasable programmable read only memory to the 1553 multiplex data bus as well data transferred from the 1553 multiplex data bus to the memory, as appropriate. The multipurpose bus interface of the present invention also includes an RS-232 interface and an RS-422 interface controlled by the digital signal processor which provides for data transfer to and from a host computer or the like into the IC memory card.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. Target of Opportunity Observing in Queue Mode at the Gemini North Observatory

    NASA Astrophysics Data System (ADS)

    Roth, Katherine; Price, P.; Gillies, K.; Walker, S.; Miller, B.

    2009-01-01

    The Gemini Observatories primarily operate a multi-instrument queue, with observers selecting observations that are best suited to weather and seeing conditions. Queue operations give higher ranked programs a greater chance for completion than lower ranked programs requesting the same conditions and instrument configuration. Queue observing naturally lends itself to Target of Opportunity (ToO) support since the time required to switch between programs and instruments is very short, and the staff observer is trained to operate all the available instruments and modes. Gemini Observatory has supported pre-approved ToO programs since beginning queue operations, and has implemented a rapid (less than 15 minutes response time) ToO mode since 2005. The rapid response ToO mode has thus far been exclusively utilized by the Gemini community for optical and near-IR follow-up of Gamma Ray Bursts (GRBs), primarily discovered by the Swift satellite. We discuss the ToO implementation at Gemini Observatory including the ToO user interface and the procedures followed by observatory staff astronomers once a ToO trigger is received. We present the statistics of 4 years of rapid ToOs at Gemini North Observatory, and the advances in our understanding of GRBs, their host galaxies and the intergalactic medium that this important mode has enabled. Finally we discuss recent changes in both software and policy to improve standard and rapid ToO support at the Gemini Observatories. The Gemini Observatory is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciìncia e Tecnologia (Brazil), and SECYT (Argentina)

  17. 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.

  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. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. Fly-by-light optical bus interface module (OBIM)

    NASA Astrophysics Data System (ADS)

    Gargano, Robert

    1995-05-01

    Driving the need for optics in flight control are the issues of wire weight, HIRF, and system bandwidth. With the advent of advanced Vehicle Management System (VMS) systems and the higher level of functional and physical integration of subsystems such as the More Electric Aircraft (MEA) and the Subsystem Utility Integration Technology (SUIT) program, optics in flight control offer attractive system benefits. Advanced VMS control functions generate large quantities of data to be transmitted over the VMS buses for processing. This paper will address the implementation of a module that will support the high throughput requirements of an advanced VMS system. The module is defined as the Optical Bus Interface Module (OBIM) and utilizes the AS1773A 20 mbps fiber optic bus for the VMS system bus. In addition, the module supports 5 mbps fiber optic Cross Channel Data Links (CCDLs) for the exchange of flight critical data in redundant architectures.

  5. 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.

  6. Dynamic behavior in two-route bus traffic system with real-time information

    NASA Astrophysics Data System (ADS)

    Nagatani, Takashi

    2014-11-01

    We study the dynamics of two-route bus traffic system with two buses using a bus choice scenario. The two-route bus traffic system with real-time information is not consistent with the two-route vehicular traffic system but is similar to the vehicular system. The two-route bus traffic system is mimicked by the physically dynamic model. The dynamics of two-route bus traffic system is described by a couple of nonlinear maps. A bus runs a neck- and neck race with another bus. The motion of two buses displays an irregular behavior in a complex manner. We clarify the effect of real-time information on the bus traffic.

  7. 49 CFR Appendix A to Part 665 - Tests To Be Performed at the Bus Testing Facility

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., low, and split-friction surfaces. The parking brake should be evaluated with the bus parked facing... static tension load equal to 1.2 times the curb weight should be applied to the bus towing...

  8. 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

    ..., low, and split-friction surfaces. The parking brake should be evaluated with the bus parked facing... static tension load equal to 1.2 times the curb weight should be applied to the bus towing...

  9. Public transit 1993: Bus, paratransit, and ridesharing. Transportation research record

    SciTech Connect

    Kassabian, N.C.; Tobias, A.G.; Crayton, L.; Solomon, N.; Brown, S.E.G.

    1993-01-01

    Contents: evaluation of the operating cost consequences of signal preemption as an IVHS strategy; efficient transit priority at intersections; welfare comparison of fixed- and flexible-route bus systems; bus stop accessibility: a guide for virginia transit systems and public entities for complying with the americans with disabilities act of 1990; implications of technological developments for demand responsive transit; impact of nonresponse bias on forecasts of average passenger occupancy; what has happened to carpooling: trends in North Carolina, 1980 to 1990; ridesharing and the consumer: a tale of two marketing strategies; transportation demand management at small employer sites; and state of the commute in Southern California, 1992.

  10. 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.

  11. 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

  12. Performance evaluation of UHF RFID technologies for real-time bus recognition in the Taipei Bus Station.

    PubMed

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

    2013-06-18

    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.

  13. Demonstration of Caterpillar C-10 dual-fuel engines in MCI 102DL3 commuter buses

    SciTech Connect

    2000-02-28

    The purpose of this program was to demonstrate the Caterpillar C-10 Dual-Fuel Natural Gas (DFNG) engine in an over-the-road bus application. Three new Motor Coach Industries (MCI) 102DL3 buses, equipped with Caterpillar C-10 DFNG engines, and one bus, equipped with a Caterpillar C-10 diesel engine, were operated side by side on similar fixed-route revenue service for a 12-month demonstration period (February 1998 to January 1999). The buses were used as part of the Clean Air Express Commuter Bus Program in Santa Barbara County, California. The performance and reliability of the DFNG engines were similar to that of the diesel engine, but the emissions results were mixed.

  14. 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…

  15. Riding the School Bus: A Comparison of the Rural and Suburban Experience in Five States.

    ERIC Educational Resources Information Center

    Howley, Craig B.; Howley, Aimee A.; Shamblen, Steven

    2001-01-01

    A study comparing rural and suburban school bus rides surveyed 1,194 elementary principals in five states. Rural elementary schools were more likely than suburban schools to have bus rides of 30 minutes of more, attendance areas greater than 10 square miles, rough rides, and older students on the bus with elementary students. (Contains 41…

  16. 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…

  17. 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.

  18. 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... private school bus operators. Private school bus operators may file written comments on an applicant's...) of the Federal Mass Transit Act of 1964, as amended (49 U.S.C. 1602(d)). The comments of...

  19. 75 FR 2583 - Over-the-Road Bus Accessibility Program Grants

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-15

    ...) announces the availability of funds in Fiscal Year (FY) 2009 for the Over-the-Road Bus (OTRB) Accessibility... of an accessible over-the-road bus are listed in 49 CFR part 38, subpart G. The rule required 50.... Specifications describing the design features of an accessible over-the-road bus are listed in 49 CFR part...

  20. Chaotic and periodic motions of a cyclic bus induced by speedup.

    PubMed

    Nagatani, Takashi

    2002-10-01

    We study the effect of speedup on the dynamical behavior of a single cyclic bus in a bus system with many bus stops. We present a nonlinear-map model of a cyclic bus to take into account the speedup. When the cyclic bus is delayed, the bus speeds up to retrieve the delay. It is found that the cyclic bus exhibits chaotic motion with increasing speedup. The chaotic motion depends on both speedup and the number of bus stops. Also, it is shown that the dynamical transition between the chaotic and periodic motions occurs with the increase of bus stops. The dependence of the recurrence time (one period) and Liapunov exponent on both speedup and the number of bus stops is calculated for distinct dynamic states. It is shown that the speedup has a significant effect on the bus motion. For a piecewise linear-map model, the cyclic bus does not exhibit the chaotic motion but a complex oscillatory motion with multiple periods occurs.

  1. 49 CFR 383.123 - Requirements for a school bus endorsement.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 5 2014-10-01 2014-10-01 false Requirements for a school bus endorsement. 383.123... Requirements for a school bus endorsement. (a) An applicant for the school bus endorsement must satisfy the... devices, external mirror systems, flashing lights, and other warning and passenger safety devices...

  2. 49 CFR 383.123 - Requirements for a school bus endorsement.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 5 2012-10-01 2012-10-01 false Requirements for a school bus endorsement. 383.123... Requirements for a school bus endorsement. (a) An applicant for the school bus endorsement must satisfy the... devices, external mirror systems, flashing lights, and other warning and passenger safety devices...

  3. History and Current Status of School Bus Driver Education in Ohio and the United States.

    ERIC Educational Resources Information Center

    Whisman, Robert W.

    The key position in any student transportation system is that of school bus driver. The driver's responsibilities are such that a specific program of school bus driver education becomes a necessity. A review of the literature reveals that no studies pertaining to school bus driver education have been made. This thesis documents the history and…

  4. 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…

  5. 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.

  6. 46 CFR 112.05-3 - Main-emergency bus-tie.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 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...

  7. 49 CFR 383.123 - Requirements for a school bus endorsement.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 5 2011-10-01 2011-10-01 false Requirements for a school bus endorsement. 383.123... Requirements for a school bus endorsement. (a) An applicant for the school bus endorsement must satisfy the... for school buses by State or Federal law or regulation. (ii) Emergency exits and procedures for...

  8. 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....

  9. 75 FR 71792 - National Express Corporation-Control Exemption-Vogel Bus Company, Inc.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-24

    ... Surface Transportation Board National Express Corporation--Control Exemption--Vogel Bus Company, Inc... approval requirements of 49 U.S.C. 14303(a)(5) and 49 CFR 1182 to acquire control of Vogel Bus Company, Inc... also primarily provides transportation of school children, in New Jersey. School bus transportation...

  10. 49 CFR 571.220 - Standard No. 220; School bus rollover protection.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 6 2011-10-01 2011-10-01 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....

  11. 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...

  12. 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

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Tests To Be Performed at the Bus Testing Facility...) FEDERAL TRANSIT ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BUS TESTING Pt. 665, App. A Appendix A to Part 665—Tests To Be Performed at the Bus Testing Facility The eight tests to be performed on...

  13. 49 CFR 383.123 - Requirements for a school bus endorsement.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Requirements for a school bus endorsement. 383.123... Requirements for a school bus endorsement. (a) An applicant for a school bus endorsement must satisfy the... devices required for school buses by State or Federal law or regulation. (ii) Emergency exits...

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

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 7 2011-10-01 2011-10-01 false Tests To Be Performed at the Bus Testing Facility...) FEDERAL TRANSIT ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BUS TESTING Pt. 665, App. A Appendix A to Part 665—Tests To Be Performed at the Bus Testing Facility The eight tests to be performed on...

  15. 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.

  16. 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…

  17. The Diagnostic and Predictive Validity of "The Renfrew Bus Story"

    ERIC Educational Resources Information Center

    Pankratz, Mary E.; Plante, Elena; Vance, Rebecca; Insalaco, Deborah M.

    2007-01-01

    Purpose: Two studies are presented providing evidence indicating the diagnostic and predictive validity of the American version of "The Renfrew Bus Story" (J. Cowley & C. Glasgow, 1994). Method: Thirty-two children with specific language impairment (SLI) and 32 children with typical language development participated in the first study to determine…

  18. Long School Bus Rides: Stealing the Joy of Childhood.

    ERIC Educational Resources Information Center

    Spence, Beth

    Every school day, hundreds of West Virginia children ride school buses much longer than state guidelines say they should. Under those guidelines, no elementary student should be on the bus more than 30 minutes one way, middle school students 45 minutes, and high school students 1 hour. In fall 1999, public hearings about school transportation…

  19. 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…

  20. 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…

  1. Increased plasma homocysteine levels in shift working bus drivers

    PubMed Central

    Martins, P; D'Almeida, V; Vergani, N; Perez, A; Tufik, S

    2003-01-01

    Background: Previous studies have indicated an association between shift work and cardiovascular disease. There is also considerable epidemiological evidence that hyperhomocysteinemia is an independent risk factor for cardiovascular disorders. Aims: To analyse plasma homocysteine levels in shift work bus drivers, and to investigate possible relations with sleep parameters and other biochemical factors. Methods: Blood samples were collected from 30 male shift working long-haul bus drivers in a Brazilian sample and analysed for plasma levels of homocysteine, folic acid, vitamin B12, and serum lipids. A group of 22 daytime workers, matched for age and body mass index served as controls. The incidence of mutations in the gene coding for methylene tetrahydrofolate, an enzyme which is related to hyperhomocysteinemia, was also assessed. Polysomnographic recordings were obtained from the target group. Results: Bus drivers showed significantly higher levels of plasma homocysteine than the control group (18.57 v 9.43 µM). Most of the other biochemical, behavioural, and molecular parameters did not differ between groups. Likewise, sleep parameters appeared to be within the normal range. Conclusions: The significantly increased plasma homocysteine levels in long-haul bus drivers did not appear to be secondary to other biochemical or behavioural problems in this group. These results suggest that hyperhomocysteinemia may be involved in the increased incidence of cardiovascular diseases observed in shift workers. PMID:12937187

  2. 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

  3. 45 CFR 1310.17 - Driver and bus monitor training.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... records as necessary. (c) Drivers must also receive instruction on the topics listed in 45 CFR 1304.52(k... with Disabilities (45 CFR 1308) relating to transportation services for children with disabilities. (d... 45 Public Welfare 4 2010-10-01 2010-10-01 false Driver and bus monitor training. 1310.17...

  4. Bullying on the School Bus: A Video Analysis

    ERIC Educational Resources Information Center

    Raskauskas, Juliana

    2005-01-01

    The purpose of this study was to assess the nature of bullying on the school bus. Videotapes were used to identify occurrences of bullying on buses of elementary school students. Incidents were reviewed for forms of bullying, fullness, presence of friends, and severity of acts. Results indicated that approximately two incidents occurred per bus…

  5. 45 CFR 1310.17 - Driver and bus monitor training.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... records as necessary. (c) Drivers must also receive instruction on the topics listed in 45 CFR 1304.52(k... with Disabilities (45 CFR 1308) relating to transportation services for children with disabilities. (d... 45 Public Welfare 4 2011-10-01 2011-10-01 false Driver and bus monitor training. 1310.17...

  6. 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…

  7. 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.

  8. 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…

  9. 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.

  10. 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…

  11. Manual for the Instruction of School Bus Drivers.

    ERIC Educational Resources Information Center

    Stewart, Otto J., Comp.

    In answer to requests from numerous school and safety officials throughout the State, a manual for the instruction of school bus drivers was prepared; with 2,000,000 pupils in 20,000 vehicles being transported daily during a school year, the State of New York realizes the necessity for correct safety procedures to be well defined for those…

  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. 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.…

  14. 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.

  15. A two-stage approach in solving the state probabilities of the multi-queue M/G/1 model

    NASA Astrophysics Data System (ADS)

    Chen, Mu-Song; Yen, Hao-Wei

    2016-04-01

    The M/G/1 model is the fundamental basis of the queueing system in many network systems. Usually, the study of the M/G/1 is limited by the assumption of single queue and infinite capacity. In practice, however, these postulations may not be valid, particularly when dealing with many real-world problems. In this paper, a two-stage state-space approach is devoted to solving the state probabilities for the multi-queue finite-capacity M/G/1 model, i.e. q-M/G/1/Ki with Ki buffers in the ith queue. The state probabilities at departure instants are determined by solving a set of state transition equations. Afterward, an embedded Markov chain analysis is applied to derive the state probabilities with another set of state balance equations at arbitrary time instants. The closed forms of the state probabilities are also presented with theorems for reference. Applications of Little's theorem further present the corresponding results for queue lengths and average waiting times. Simulation experiments have demonstrated the correctness of the proposed approaches.

  16. 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

  17. 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

  18. 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

  19. GeoBus: sharing science research with schools

    NASA Astrophysics Data System (ADS)

    Roper, Kathryn; Robinson, Ruth; Moorhouse, Ben

    2016-04-01

    GeoBus (www.geobus.org.uk) is an educational outreach project that was developed in 2012 by the Department of Earth and Environmental Sciences at the University of St Andrews, and it is currently sponsored by industry, NERC, The Crown Estate, and the Scottish Government. The aims of GeoBus are to support the teaching of Earth Science in secondary (middle and high) schools by providing teaching support to schools that have little or no experience in teaching this subject. This is, in part, done through the sharing of new science research outcomes and the experiences of young researchers with school pupils to provide a bridge between industry, higher education institutions, research councils and schools. Since its launch, over 40,000 pupils will have been involved in experiential Earth science learning activities in 190 different schools (over 400 separate visits) across the length and breadth of Scotland: many of these schools are in remote and disadvantaged regions. A new GeoBus project is under development within the Department of Earth Sciences at UCL in London. A key aim of GeoBus is to incorporate new research into our workshops with the main challenge being the development of appropriate resources that incorporate the key learning aims and requirements of the science and geography curricula. GeoBus works closely with researchers, teachers and educational practitioners to tailor the research outcomes to the curricula as much as possible. Over the past four years, GeoBus has developed 17 workshops, 5 challenge events and extensive field trips and each of these activities are trialled and evaluated within the university, and adjustments are made before the activities are delivered in schools. Activities are continually reviewed and further developments are made in response to both teacher and pupil feedback. This critical reflection of the project's success and impact is important to insure a positive and significant contribution to the science learning in

  20. 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.

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

    PubMed

    Jurčev-Savičević, Anamarija; Bradarić, Nikola; Paić, Vlado Ozic; Mulić, Rosanda; Puntarić, Dinko; Miše, 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.

  2. 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.

  3. 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.

  4. 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.

  5. Dynamics of dc bus networks and their stabilization by decentralized delayed feedback.

    PubMed

    Konishi, Keiji; Sugitani, Yoshiki; Hara, Naoyuki

    2015-01-01

    The present paper deals with the dynamics of bus networks, which consist of several identical dc bus systems connected by resistors. It is analytically guaranteed that the stability of a stand-alone dc bus system is equivalent to that of the networks, independent of the number of bus systems and the network topology. In addition, we show that a decentralized delayed-feedback control can stabilize an unstable operating point embedded within the networks. Moreover, this stabilization does not depend on the number of bus systems or the network topology. A systematic procedure for designing the controller is presented. Finally, the validity of the analytical results is confirmed through numerical examples.

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

    PubMed Central

    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

  7. Dynamics of dc bus networks and their stabilization by decentralized delayed feedback

    NASA Astrophysics Data System (ADS)

    Konishi, Keiji; Sugitani, Yoshiki; Hara, Naoyuki

    2015-01-01

    The present paper deals with the dynamics of bus networks, which consist of several identical dc bus systems connected by resistors. It is analytically guaranteed that the stability of a stand-alone dc bus system is equivalent to that of the networks, independent of the number of bus systems and the network topology. In addition, we show that a decentralized delayed-feedback control can stabilize an unstable operating point embedded within the networks. Moreover, this stabilization does not depend on the number of bus systems or the network topology. A systematic procedure for designing the controller is presented. Finally, the validity of the analytical results is confirmed through numerical examples.

  8. 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.

  9. Determination of an Optimal Commercial Data Bus Architecture for a Flight Data System

    NASA Technical Reports Server (NTRS)

    Crawford, Kevin; Johnson, Martin; Humphries, Rick (Technical Monitor)

    2001-01-01

    NASA/Marshall Space Flight Center (MSFC) is continually looking for methods to reduce cost and schedule while keeping the quality of work high. MSFC is NASA's lead center for space transportation and microgravity research. When supporting NASA's programs several decisions concerning the avionics system must be made. Usually many trade studies must be conducted to determine the best ways to meet the customer's requirements. When deciding the flight data system, one of the first trade studies normally conducted is the determination of the data bus architecture. The schedule, cost, reliability, and environments are some of the factors that are reviewed in the determination of the data bus architecture. Based on the studies, the data bus architecture could result in a proprietary data bus or a commercial data bus. The cost factor usually removes the proprietary data bus from consideration. The commercial data bus's range from Versa Module Eurocard (VME) to Compact PCI to STD 32 to PC 104. If cost, schedule and size are prime factors, VME is usually not considered. If the prime factors are cost, schedule, and size then Compact PCI, STD 32 and PC104 are the choices for the data bus architecture. MSFC's center director has funded a study from his discretionary fund to determine an optimal low cost commercial data bus architecture. The goal of the study is to functionally and environmentally test Compact PCI, STD 32 and PC 104 data bus architectures. This paper will summarize the results of the data bus architecture study.

  10. 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...

  11. 40 CFR 85.1404 - Maintenance of records for urban bus operators; submittal of information; right of entry.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 18 2010-07-01 2010-07-01 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...

  12. 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.

  13. Performance analysis for queueing systems with close down periods and server under maintenance

    NASA Astrophysics Data System (ADS)

    Krishna Kumar, B.; Anbarasu, S.; Lakshmi, S. R. Anantha

    2015-01-01

    A single server queue subject to maintenance of the server and the close down period is considered. We obtain explicit expressions for the transient probabilities of the system size, the server under maintenance state and the close down period. The time-dependent performance measures of the system and the probability density function of the first-passage-time to reach the maintenance state are discussed. The corresponding steady state analysis and key performance measures of the system are also presented. Finally, the effect of various parameters on system performance measures is demonstrated by a numerical example.

  14. 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.

  15. Method, apparatus and system for managing queue operations of a test bench environment

    DOEpatents

    Ostler, Farrell Lynn

    2016-07-19

    Techniques and mechanisms for performing dequeue operations for agents of a test bench environment. In an embodiment, a first group of agents are each allocated a respective ripe reservation and a second set of agents are each allocated a respective unripe reservation. Over time, queue management logic allocates respective reservations to agents and variously changes one or more such reservations from unripe to ripe. In another embodiment, an order of servicing agents allocated unripe reservations is based on relative priorities of the unripe reservations with respect to one another. An order of servicing agents allocated ripe reservations is on a first come, first served basis.

  16. 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.

  17. An evaluation of a lane support system for bus rapid transit on narrow shoulders and the relation to bus driver mental workload.

    PubMed

    Ward, Nicholas J; Shankwitz, Craig; Gorgestani, Alec; Donath, Max; De Waard, Dick; Boer, Erwin R

    2006-07-15

    The use of dedicated bus shoulders is a key method for implementing bus rapid transit (BRT) in areas that do not have the space for additional infrastructure. However, the narrow width of the bus shoulder and the need to anticipate traffic hazards in the adjacent lane can both be significant stressors for bus drivers. Bus driver mental workload and stress in response to these conditions should be a significant concern both for operational safety and driver health. This pilot study evaluated the potential stressors of traffic density and shoulder width in the context of an express BRT service in a large US metropolitan area. In addition, the study considered the potential role of a prototype lane support system (LSS) to support vehicle control within the narrow shoulder boundaries. Ten experienced bus drivers drove an actual route with an instrumented bus equipped with and without LSS. Self-reported effort was recorded along with performance measures of speed and position control relevant to mobility and safety objectives. Bus drivers did note stressors in the BRT environment and the prototype LSS. However, the use of the shoulder during high-density traffic conditions did improve mobility. Moreover, the LSS did enhance safety on the shoulder when there was high-density traffic in the adjacent lane. However, there was no evidence that the LSS reduced bus driver workload while operating in the narrow shoulder. Future research should consider the impact of BRT operations and support systems on bus driver mental workload and stress, and support the deployment of such devices for bus operations on shoulders during high traffic volumes.

  18. Finite Buffer GI/M(n)/1 Queue with Bernoulli-Schedule Vacation Interruption under N-Policy.

    PubMed

    Vijaya Laxmi, P; Suchitra, V

    2014-01-01

    We study a finite buffer N-policy GI/M(n)/1 queue with Bernoulli-schedule vacation interruption. The server works with a slower rate during vacation period. At a service completion epoch during working vacation, if there are at least N customers present in the queue, the server interrupts vacation and otherwise continues the vacation. Using the supplementary variable technique and recursive method, we obtain the steady state system length distributions at prearrival and arbitrary epochs. Some special cases of the model, various performance measures, and cost analysis are discussed. Finally, parameter effect on the performance measures of the model is presented through numerical computations. PMID:27355076

  19. Finite Buffer GI/M(n)/1 Queue with Bernoulli-Schedule Vacation Interruption under N-Policy.

    PubMed

    Vijaya Laxmi, P; Suchitra, V

    2014-01-01

    We study a finite buffer N-policy GI/M(n)/1 queue with Bernoulli-schedule vacation interruption. The server works with a slower rate during vacation period. At a service completion epoch during working vacation, if there are at least N customers present in the queue, the server interrupts vacation and otherwise continues the vacation. Using the supplementary variable technique and recursive method, we obtain the steady state system length distributions at prearrival and arbitrary epochs. Some special cases of the model, various performance measures, and cost analysis are discussed. Finally, parameter effect on the performance measures of the model is presented through numerical computations.

  20. 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.

  1. Markovian queue optimisation analysis with an unreliable server subject to working breakdowns and impatient customers

    NASA Astrophysics Data System (ADS)

    Liou, Cheng-Dar

    2015-09-01

    This study investigates an infinite capacity Markovian queue with a single unreliable service station, in which the customers may balk (do not enter) and renege (leave the queue after entering). The unreliable service station can be working breakdowns even if no customers are in the system. The matrix-analytic method is used to compute the steady-state probabilities for the number of customers, rate matrix and stability condition in the system. The single-objective model for cost and bi-objective model for cost and expected waiting time are derived in the system to fit in with practical applications. The particle swarm optimisation algorithm is implemented to find the optimal combinations of parameters in the pursuit of minimum cost. Two different approaches are used to identify the Pareto optimal set and compared: the epsilon-constraint method and non-dominate sorting genetic algorithm. Compared results allow using the traditional optimisation approach epsilon-constraint method, which is computationally faster and permits a direct sensitivity analysis of the solution under constraint or parameter perturbation. The Pareto front and non-dominated solutions set are obtained and illustrated. The decision makers can use these to improve their decision-making quality.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  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. City of Chula Vista hydrogen fuel cell bus demonstration project

    SciTech Connect

    Gustafson, B.; Bamberger, B.

    1996-10-01

    Hydrogen as an energy carrier and fuel has potential for various uses including electricity, commercial, residential, transportation, and industrial. It is an energy carrier that can be produced from a variety of primary sources and potentially can accomplish these various uses while significantly reducing pollution by substituting for or reducing the use of fossil fuels. One of the most immediate and potentially viable roles for hydrogen as an energy carrier will be its use as a transportation fuel, especially in densely populated urban areas where automotive emissions contribute significantly to air pollution. The Department of Energy`s commitment to research and development of hydrogen as an alternative fuel, and California`s Zero Emission Vehicle (ZEV) requirements, both provide the impetus and favorable circumstance for demonstrating hydrogen as a transportation fuel on an urban bus system. The purpose of this project is to demonstrate the feasibility of using solid polymer fuel cells in a hydrogen-powered electric drive system for an urban transit bus application. Fuel cell buses use hydrogen fuel and oxygen from the air to produce electrical power with the only byproduct being pure water. Proton Exchange Membrane (PEM) fuel cells are proposed for this project. Current evidence suggests that fuel cells, which rely on hydrogen and a process known as proton exchange to generate their power, appear to have an infinite life span. All exhaust pollution is completely eliminated, resulting in a Zero Emission Vehicle (ZEV). An urban bus system offers the potential for developing a market for the production of hydrogen propulsion technology due to extensive vehicular use in densely populated areas experiencing pollution from numerous sources, and because the central garaging facilities or the bus system facilitates fueling and maintenance functions.

  10. 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.

  11. 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.

  12. Bus rounds for palliative care education in the community

    PubMed Central

    Bruera, E; Selmser, P; Pereira, J; Brenneis, C

    1997-01-01

    Increasingly, patients with cancer are dying at home and in continuing care facilities. The purpose of bus rounds is to provide continuing education to physicians and nurse palliative care consultants, to familiarize family physicians with the delivery of care in these settings and to educate family medicine and specialty residents as well as medical students. A total of 18 4-hour bus rounds took place during 1996. A mean of 13 (range 9 to 17) participants attended, to discuss a mean of 3.5 (range 2 to 4) patients and 4.5 (range 3 to 8) journal articles. A questionnaire was filled out anonymously by 18 first-time medical and 24 first-time nursing participants. On a scale from 1 (worst) to 5 (best), they gave the rounds an overall rating of 5 (range 4 to 5). The mean cost per round was $245.40. The authors conclude that bus rounds provide an opportunity for intensive exposure to community-based learning for physicians, nurses and students and are highly satisfactory from the participants' perspective. PMID:9307561

  13. 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.

  14. 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

  15. Measuring job quality: a study with bus drivers.

    PubMed

    Jones, Wendy; Haslam, Roger; Haslam, Cheryl

    2014-11-01

    There is growing interest in the contribution which job design can make to worker health; also a desire to better understand the multidimensional notion of 'job quality' and to develop approaches to measuring this. This paper reviews concepts of 'job quality' and 'good jobs' and examines these issues in the work of bus drivers, an occupational group commonly reported as having poor health and poor working conditions. The DGB-Index (Deutscher Gewerkschaftsbund Good Work Index), a tool used recently in Germany for measuring job quality, was translated and administered to a sample of UK bus drivers (n = 381). It found job quality to be significantly lower than that for a group of non-drivers in the same organisation; and better than that for a sample of German bus drivers. We conclude that the DGB-Index is an effective tool for measuring job quality and providing feedback to employers; and could be used to compare job quality between organisations or internationally. PMID:24942323

  16. Fuel cell transit bus development & commercialization programs at Gerogetown University

    SciTech Connect

    Wimmer, R.; Larkins, J.; Romano, S.

    1996-12-31

    Fourteen years ago, Georgetown University (GU) perceived the need for a clean, efficient power systems for transportation that could operate on non-petroleum based fuels. The transit bus application was selected to begin system development. GU recognized the range and recharge constraints of a pure battery powered transit bus. A Fuel Cell power system would circumvent these limitations and, with an on board reformer, accommodate liquid fuel for rapid refueling. Feasibility studies for Fuel Cell power systems for transit buses were conducted with the Los Alamos National Laboratory in 1983. Successful results of this investigation resulted in the DOT/DOE Fuel Cell transit bus development program. The first task was to prove that small Fuel Cell power plants were possible. This was achieved with the Phase I development of two 25 kW Phosphoric Acid Fuel Cell (PAFC) brassboard systems. A liquid cooled version was selected for the Phase II activity in which three 30-foot Fuel Cell powered Test Bed Buses (TBBs) were fabricated. The first of these TBBs was delivered in the spring of 1994. All three of these development vehicles are now in Phase III of the program to conduct testing and evaluation, is conducting operational testing of the buses. The test will involve two fuel cell-operated buses; one with a proton exchange fuel cell and the other with a phosphoric acid fuel cell.

  17. 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.

  18. 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.

  19. 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

  20. Measuring job quality: a study with bus drivers.

    PubMed

    Jones, Wendy; Haslam, Roger; Haslam, Cheryl

    2014-11-01

    There is growing interest in the contribution which job design can make to worker health; also a desire to better understand the multidimensional notion of 'job quality' and to develop approaches to measuring this. This paper reviews concepts of 'job quality' and 'good jobs' and examines these issues in the work of bus drivers, an occupational group commonly reported as having poor health and poor working conditions. The DGB-Index (Deutscher Gewerkschaftsbund Good Work Index), a tool used recently in Germany for measuring job quality, was translated and administered to a sample of UK bus drivers (n = 381). It found job quality to be significantly lower than that for a group of non-drivers in the same organisation; and better than that for a sample of German bus drivers. We conclude that the DGB-Index is an effective tool for measuring job quality and providing feedback to employers; and could be used to compare job quality between organisations or internationally.

  1. 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.

  2. 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.

  3. 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.

  4. Hydrogen-oxygen driven Zero Emissions bus draws attention at KSC

    NASA Technical Reports Server (NTRS)

    1999-01-01

    KSC workers, with Center Director Roy Bridges (at right next to bus), head for the open door of the Zero Emissions (ZE) transit bus and a ride around the center. Provided by dbb fuel cell engines inc. of Vancouver, Canada, the ZE bus was brought to KSC as part of the Center's Alternative Fuel Initiatives Program. The bus uses a Proton Exchange Membrane fuel cell in which hydrogen and oxygen, from atmospheric air, react to produce electricity that powers an electric motor drive system. The by-product 'exhaust' from the fuel cell is water vapor, thus zero harmful emissions. A typical diesel-powered bus emits more than a ton of harmful pollutants from its exhaust every year. Available to employees for viewing and a ride, the ZE bus is also being used on tour routes at the KSC Visitor Complex Oct. 26-27.

  5. The influence of bus stop on traffic flow with velocity-difference-separation model

    NASA Astrophysics Data System (ADS)

    Zheng, Pengjun; Wang, Wei; Ge, Hongxia

    2016-06-01

    Based on velocity-difference-separation model, the mixed traffic flow on two-lane road is investigated. For a fixed road length, the influence of bus and bus stops on traffic flow is studied with the increasing traffic density. Compared with the result without bus stops given by Li et al., a new traffic state is found, which is valuable for studying the impacts of public transport on urban traffic flow.

  6. 46 CFR 112.05-3 - Main-emergency bus-tie.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... AND POWER SYSTEMS General § 112.05-3 Main-emergency bus-tie. Each bus-tie between a main switchboard... 46 Shipping 4 2014-10-01 2014-10-01 false Main-emergency bus-tie. 112.05-3 Section 112.05-3... other source of electric power, except for interlock systems for momentary transfer of loads; and (c)...

  7. 46 CFR 112.05-3 - Main-emergency bus-tie.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... AND POWER SYSTEMS General § 112.05-3 Main-emergency bus-tie. Each bus-tie between a main switchboard... 46 Shipping 4 2012-10-01 2012-10-01 false Main-emergency bus-tie. 112.05-3 Section 112.05-3... other source of electric power, except for interlock systems for momentary transfer of loads; and (c)...

  8. 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.

  9. 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.

  10. 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.

  11. An interactive wireless communication system for visually impaired people using city bus transport.

    PubMed

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

    2014-04-25

    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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Dual relationships in psychotherapy.

    PubMed

    Pope, Kenneth S

    1991-01-01

    A dual relationship in psychotherapy occurs when the therapist engages in another, significantly different relationship with the patient. The two relationships may be concurrent or sequential. For both sexual and nonsexual dual relationships, men are typically the perpetrators and women are typically the victims. This article presents examples of dual relationships, notes the attention that licensing boards and other agencies devote to this topic, reviews the meager research concerning nonsexual dual relationships, and discusses common strategies that promote both sexual and nonsexual dual relationships. PMID:11649348

  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. Infinite capacity multi-server queue with second optional service channel

    NASA Astrophysics Data System (ADS)

    Ke, Jau-Chuan; Wu, Chia-Huang; Pearn, Wen Lea

    2013-02-01

    This paper deals with an infinite-capacity multi-server queueing system with a second optional service (SOS) channel. The inter-arrival times of arriving customers, the service times of the first essential service (FES) and the SOS channel are all exponentially distributed. A customer may leave the system after the FES channel with probability (1-θ), or at the completion of the FES may immediately require a SOS with probability θ (0 <= θ <= 1). The formulae for computing the rate matrix and stationary probabilities are derived by means of a matrix analytical approach. A cost model is developed to determine the optimal values of the number of servers and the two service rates, simultaneously, at the minimal total expected cost per unit time. Quasi-Newton method are employed to deal with the optimization problem. Under optimal operating conditions, numerical results are provided in which several system performance measures are calculated based on assumed numerical values of the system parameters.

  3. Effect of information, uncertainty and parameter variability on profits in a queue with various pricing strategies

    NASA Astrophysics Data System (ADS)

    Sun, Wei; Li, Shiyong

    2014-08-01

    This paper presents an unobservable single-server queueing system with three types of uncertainty, where the service rate, or waiting cost or service quality is random variable that may obtain n(n > 2) values. The information about the realised values of parameters is only known to the server. We are concerned about the server's behaviour: revealing or concealing the information to customers. The n-value assumption and the server's behaviour enable us to consider various pricing strategies. In this paper, we analyse the effect of information and uncertainty on profits and make comparisons between the profits under different pricing strategies. Moreover, as for parameter variability reflected by the number of each parameter's possible choices n, we observe the effect of variable n on all types of profits and find that revealing the parameter information can much more benefit the server with the increase of n.

  4. A processor-shared queue that models switching times: Heavy usage asymptotics

    SciTech Connect

    Knessl, C.; Tier, C. . Dept. of Mathematics, Statistics, and Computer Science)

    1994-06-01

    A closed processor-sharing queueing model that corresponds to M terminals in series with a central processing unit (CPU) is considered under heavy usage conditions. The effects of switching times between the CPU and the individual jobs are included by assuming that the effective service rate that the CPU provides is a decreasing function of the instantaneous number of jobs being processed. Using perturbation methods, asymptotic expansions are constructed for the first two moments of a customer's response (sojourn) time, conditioned on that customer's total required service from the CPU. The asymptotic limit assumes that the number of terminals M is large (M [much gt] 1), that the rate at which the CPU provides service is fast (O(M)), and that the duration of a typical switching time is small compared to the time the CPU actually spends servicing the individual jobs. Extensive numerical comparisons show the quality of the asymptotic approximations.

  5. 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.

  6. Data systems - Optical bus will connect distributed system

    NASA Technical Reports Server (NTRS)

    Swingle, W. L.

    1983-01-01

    The fiber optics buses currently under consideration for the NASA space station program will have data rates of at least 20 Mb/sec. The network interconnection scheme that will eventually be used is, however, uncertain. A NASA-Langley effort on graph networks includes adaptive, fault-tolerant and self-correcting operations. A breadboard program at NASA-Johnson includes evaluations of standard devices, called 'bus interface units', in an adaptive and fault-correcting chordal or concentric ring type of network. Fiber optics would allow an evolution to wavelength modulation techniques in such systems.

  7. 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.

  8. 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.

  9. 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

  10. Digital pointing control. [for Space Shuttle Data Bus

    NASA Technical Reports Server (NTRS)

    Studer, P. A.; Brown, R. J.

    1978-01-01

    The digital pointing control system developed for the Space Shuttle Data Bus is discussed. The device, which interfaces with NASA standard sensor units, contains a front panel controller, a development system to load, inspect, print, and store the program and data, and a 'test jig' to provide closed-loop controller operation. The system is described with particular reference to the tracker-gyro interfaces, the control algorithms and compensation procedures, Kalman-estimation filtering, the proportional power output, and the discrete output capability. The results of simulation studies are presented and the development status is noted.

  11. Increasing carbonmonoxide blood levels in Bangkok bus drivers

    SciTech Connect

    Saenghirunvattana, S.; Wananukul, W.; Mokkhavesa, C.; Opasi, N.

    1995-05-01

    In order to study the effects of air pollution in Bangkok, 31 bus drivers were examined and blood was drawn for measurement of carboxyhemoglobin (COHb) prior to and after work. The COHb level before work was 2.19{+-}2.46% (range 0.7.18). It had increased after work to 5.26{+-}2.52% (range 0-10.4) (p<0.001). Twenty-one drivers complained of chronic headaches, myalgia, and eye irritation during working hours. The COHb level was not statistically different between smokers and nonsmokers.

  12. 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.

  13. 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.

  14. Using School Bus Discipline Referral Data in Decision Making: Two Case Studies

    ERIC Educational Resources Information Center

    Hirsch, Edward J.; Lewis-Palmer, Teri; Sugai, George; Schnacker, Lance

    2004-01-01

    Public schools are responsible for providing a safe, structured environment that is conducive to learning. This requirement encompasses a variety of settings, including school bus transportation. However, limited research exists to indicate best practices for designing and implementing behavior programs for school bus transportation. The…

  15. 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…

  16. 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…

  17. 49 CFR Appendix A to Part 665 - Tests To Be Performed at the Bus Testing Facility

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... components that would be expected to require replacement during the bus's normal life cycle. Much of the... operability of all passenger doors, passenger escape mechanisms, windows, and service doors. A water leak test... using duty cycles that simulate transit service. This test should measure the fuel economy of the bus...

  18. 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.

  19. 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...

  20. 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...

  1. 76 FR 17738 - Over-the-Road Bus Accessibility Program Announcement of Project Selections

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-30

    ... Federal Transit Administration Over-the-Road Bus Accessibility Program Announcement of Project Selections... be funded under Fiscal Year (FY) 2009 and 2010 appropriations for the Over-the- Road Bus (OTRB...). The OTRB Accessibility Program makes funds available to private operators of over-the-road buses...

  2. 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...

  3. 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...

  4. 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)...

  5. School Bus Routing and Scheduling: When to Use Computer-Assisted Methods and Programs.

    ERIC Educational Resources Information Center

    Walcott, Wayne; And Others

    1986-01-01

    Discusses issues concerning the use of computers in school bus scheduling and routing. Examines the advantages, technical considerations, and costs of changing to a computerized system. Offers a five-point approach toward implementation and includes a table of comparative data for routing and scheduling models for a typical school bus fleet. (IW)

  6. 49 CFR 383.123 - Requirements for a school bus endorsement.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 5 2013-10-01 2013-10-01 false Requirements for a school bus endorsement. 383.123... § 383.91(a)) as the school bus applicant will drive. (b) Exception. Knowledge and skills tests administered before September 30, 2002 and approved by FMCSA as meeting the requirements of this section,...

  7. Simulation of bended planar waveguides for optical bus-couplers

    NASA Astrophysics Data System (ADS)

    Lorenz, Lukas; Nieweglowski, Krzysztof; Wolter, Klaus-Jürgen; Bock, Karlheinz

    2016-04-01

    In our work an optical bus-coupler is proposed, which enables easy bidirectional connection between two waveguides without interrupting the bus using a core-to-core coupling principle. With bended waveguides the coupling ratio can be tuned by adjusting the overlap area of the two cores. In order to ensure large overlap areas at short coupling lengths, the waveguides have rectangular cross sections. To examine the feasibility of this coupling concept a simulation was performed, which is presented in this paper. Due to multimode waveguides, used in short range data communication, a non-sequential ray tracing simulation is reasonable. Simulations revealed that the bending of the waveguide causes a redistribution of the energy within the core. Small radii push the main energy to the outer region of the core increasing the coupling efficiency. On the other hand, at excessive lowered bend radii additional losses occur (due to a coupling into the cladding), which is why an optimum has to be found. Based on the simulation results it is possible to derive requirements and design rules for the coupling element.

  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. 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.

  10. Hydrogen-oxygen driven Zero Emissions bus drives around KSC Visitor Complex

    NASA Technical Reports Server (NTRS)

    1999-01-01

    The Zero Emissions (ZE) transit bus passes a mock-up orbiter named Explorer on a trek through the KSC Visitor Complex. Provided by dbb fuel cell engines inc. of Vancouver, Canada, the ZE bus was brought to KSC as part of the Center's Alternative Fuel Initiatives Program. The bus uses a Proton Exchange Membrane fuel cell in which hydrogen and oxygen, from atmospheric air, react to produce electricity that powers an electric motor drive system. The by-product 'exhaust' from the fuel cell is water vapor, thus zero harmful emissions. A typical diesel-powered bus emits more than a ton of harmful pollutants from its exhaust every year. The ZE bus is being used on tour routes at the KSC Visitor Complex for two days to introduce the public to the concept.

  11. 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.

  12. 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.

  13. Hydrogen-oxygen driven Zero Emissions bus drives around KSC Visitor Complex

    NASA Technical Reports Server (NTRS)

    1999-01-01

    The Zero Emissions (ZE) transit bus tours the KSC Visitor Complex for a test ride. In the background are a mock-up orbiter named Explorer (left) and a stack of solid rocket boosters and external tank (right), typically used on Shuttle launches. Provided by dbb fuel cell engines inc. of Vancouver, Canada, the ZE bus was brought to KSC as part of the Center's Alternative Fuel Initiatives Program. The bus uses a Proton Exchange Membrane fuel cell in which hydrogen and oxygen, from atmospheric air, react to produce electricity that powers an electric motor drive system. The by-product 'exhaust' from the fuel cell is water vapor, thus zero harmful emissions. A typical diesel-powered bus emits more than a ton of harmful pollutants from its exhaust every year. The ZE bus is being used on tour routes at the KSC Visitor Complex for two days to introduce the public to the concept.

  14. High concurrency data bus using arrays of optical emitters and detectors.

    PubMed

    Thomas Cathey, W; Smith, B J

    1979-05-15

    A data bus is described that allows simultaneous transfers of multiple bit words among various components within a computer, thereby permitting many parallel operations. The bus is composed of sparsely filled arrays of light emitters that are imaged onto similar arrays of detectors. Direct connections between the units in the computer are made via the light paths through the imaging system. A 2-D addressing scheme on the array reduces the number of electrical connections between the arrays of the data bus and the computer components to which they are connected. The result is a data bus with dedicated optical paths to all units in the computer but without the need for a large number of electrical connections. The operation of the bus and the addressing and driving methods are described, and results of preliminary experiments are given.

  15. Dynamics of dc bus networks and their stabilization by decentralized delayed feedback.

    PubMed

    Konishi, Keiji; Sugitani, Yoshiki; Hara, Naoyuki

    2015-01-01

    The present paper deals with the dynamics of bus networks, which consist of several identical dc bus systems connected by resistors. It is analytically guaranteed that the stability of a stand-alone dc bus system is equivalent to that of the networks, independent of the number of bus systems and the network topology. In addition, we show that a decentralized delayed-feedback control can stabilize an unstable operating point embedded within the networks. Moreover, this stabilization does not depend on the number of bus systems or the network topology. A systematic procedure for designing the controller is presented. Finally, the validity of the analytical results is confirmed through numerical examples. PMID:25679686

  16. Hydrogen-oxygen driven Zero Emissions bus draws attention at KSC

    NASA Technical Reports Server (NTRS)

    1999-01-01

    KSC employees, along with Center Director Roy Bridges (second from left), view the hydrogen-oxygen driven engine powering a Zero Emissions (ZE) transit bus. Provided by dbb fuel cell engines inc. of Vancouver, Canada, the ZE bus was brought to KSC as part of the Center's Alternative Fuel Initiatives Program. The bus uses a Proton Exchange Membrane fuel cell in which hydrogen and oxygen, from atmospheric air, react to produce electricity that powers an electric motor drive system. The by-product 'exhaust' from the fuel cell is water vapor, thus zero harmful emissions. A typical diesel-powered bus emits more than a ton of harmful pollutants from its exhaust every year. Available for viewing by employees, the ZE bus is also being used on tour routes at the KSC Visitor Complex Oct. 26-27.

  17. Hydrogen-oxygen driven Zero Emissions bus draws attention at KSC

    NASA Technical Reports Server (NTRS)

    1999-01-01

    In front of the Headquarters Building at KSC, Center Director Roy Bridges (left) looks at the hydrogen-oxygen driven engine powering a Zero Emissions (ZE) transit bus. Provided by dbb fuel cell engines inc. of Vancouver, Canada, the ZE bus was brought to KSC as part of the Center's Alternative Fuel Initiatives Program. The bus uses a Proton Exchange Membrane fuel cell in which hydrogen and oxygen, from atmospheric air, react to produce electricity that powers an electric motor drive system. The by- product 'exhaust' from the fuel cell is water vapor, thus zero harmful emissions. A typical diesel-powered bus emits more than a ton of harmful pollutants from its exhaust every year. Available for viewing by employees, the ZE bus is also being used on tour routes at the KSC Visitor Complex Oct. 26-27.

  18. Hydrogen-oxygen driven Zero Emissions bus draws attention at KSC

    NASA Technical Reports Server (NTRS)

    1999-01-01

    On view in front of the Headquarters Building, the Zero Emissions (ZE) transit bus attracts an interested group of employees, including Center Director Roy Bridges (second from left in foreground). Provided by dbb fuel cell engines inc. of Vancouver, Canada, the ZE bus was brought to KSC as part of the Center's Alternative Fuel Initiatives Program. The bus uses a Proton Exchange Membrane fuel cell in which hydrogen and oxygen, from atmospheric air, react to produce electricity that powers an electric motor drive system. The by-product 'exhaust' from the fuel cell is water vapor, thus zero harmful emissions. A typical diesel-powered bus emits more than a ton of harmful pollutants from its exhaust every year. Available for viewing by employees, the ZE bus is also being used on tour routes at the KSC Visitor Complex Oct. 26-27.

  19. 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.

  20. Optimal management for infinite capacity N-policy M/G/1 queue with a removable service station

    NASA Astrophysics Data System (ADS)

    Chang, Y. C.; Pearn, W. L.

    2011-07-01

    In this article, we consider an infinite capacity N-policy M/G/1 queueing system with a single removable server. Poisson arrivals and general distribution service times are assumed. The server is controllable that may be turned on at arrival epochs or off at service completion epochs. We apply a differential technique to study system sensitivity, which examines the effect of different system input parameters on the system. A cost model for infinite capacity queueing system under steady-state condition is developed, to determine the optimal management policy at minimum cost. Analytical results for sensitivity analysis are derived. We also provide extensive numerical computations to illustrate the analytical sensitivity properties obtained. Finally, an application example is presented to demonstrate how the model could be used in real applications to obtain the optimal management policy.

  1. Approximation of an M/M/s queue by the M/M/∞ one using the operator mathod

    NASA Astrophysics Data System (ADS)

    Bareche, A.; Cherfaoui, M.; Aïssani, D.

    2016-08-01

    In this paper, we provide an approximate analysis of an M/M/s queue using the operator method (strong stability method). Indeed, we use this approach to study the stability of the M/M/∞ system (ideal system), when it is subject to a small perturbation in its structure (M/M/s is the resulting perturbed system). In other words, we are interested in the approximation of the characteristics of an M/M/s system by those of an M/M/∞ one. For this purpose, we first determine the approximation conditions of the characteristics of the perturbed system, and under these conditions we obtain the stability inequalities for the stationary distribution of the queue size. To evaluate the performance of the proposed method, we develop an algorithm which allows us to compute the various obtained theoretical results and which is executed on the considered systems in order to compare its output results with those of simulation.

  2. 25 CFR 39.710 - How does a school calculate annual bus transportation miles for day students?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 25 Indians 1 2011-04-01 2011-04-01 false How does a school calculate annual bus transportation... Miles § 39.710 How does a school calculate annual bus transportation miles for day students? To calculate the total annual bus transportation miles for day students, a school must use the...

  3. 78 FR 40268 - Conway's Bus Service, Inc.-Sale Of Certain Assets-Academy Express, L.L.C.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-03

    ... Surface Transportation Board Conway's Bus Service, Inc.--Sale Of Certain Assets--Academy Express, L.L.C... Transaction. SUMMARY: On June 4, 2013, Conway's Bus Service, Inc. (CBS), and Academy Express, L.L.C. (Academy..., ``Conway's Bus Service.'' According to Applicants, CBS has two other separate and distinct...

  4. 25 CFR 39.710 - How does a school calculate annual bus transportation miles for day students?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false How does a school calculate annual bus transportation... Miles § 39.710 How does a school calculate annual bus transportation miles for day students? To calculate the total annual bus transportation miles for day students, a school must use the...

  5. 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.

  6. 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.

  7. Optimal control strategy design based on dynamic programming for a dual-motor coupling-propulsion system.

    PubMed

    Zhang, Shuo; Zhang, Chengning; Han, Guangwei; Wang, Qinghui

    2014-01-01

    A dual-motor coupling-propulsion electric bus (DMCPEB) is modeled, and its optimal control strategy is studied in this paper. The necessary dynamic features of energy loss for subsystems is modeled. Dynamic programming (DP) technique is applied to find the optimal control strategy including upshift threshold, downshift threshold, and power split ratio between the main motor and auxiliary motor. Improved control rules are extracted from the DP-based control solution, forming near-optimal control strategies. Simulation results demonstrate that a significant improvement in reducing energy loss due to the dual-motor coupling-propulsion system (DMCPS) running is realized without increasing the frequency of the mode switch.

  8. 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.

  9. Dual fuel Russian urban transit buses: Economical reduced emissions. Export trade information

    SciTech Connect

    1998-01-01

    This study, conducted by Caterpillar, was funded by the US Trade and Development Agency. The scope of this project was to examine the financial and environmental aspects of introducing new alternative fuel engines to the buses of Russia`s public transportation system. The report consists of the following: (1) executive summary; (2) background/overview; (3) 3306 design, development, test; (4) electronic governed engines; (5) Moscow bus testing; (6) conclusions; (7) appendices. The appendices include: (1) Caterpillar emissions lab report; (2) dyno tests -- dual fuel data sheets; (3) 3360 horizontal engine lub tilt test; (4) 1000 hour endurance test -- engine operator sheets; (5) 1000 hour endurance test -- 250 hour check; (6) Caterpillar dual fuel electronic engines; (7) product description -- dual fuel electronic governed engines; (8) California Environmental Protection Agency -- certification of caterpillar electronic governed engines; (9) annual payback data.

  10. 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.

  11. 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

  12. 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

  13. The Dual Career Family.

    ERIC Educational Resources Information Center

    Gurtin, Lee

    1980-01-01

    The dual career couple is forced to make a series of choices and compromises that impact the realms of marriage and career. The dilemmas that confront dual career marriages can be overcome only by compromise, accommodation, and mutual understanding on the part of the individuals involved. A revamping of human resources and recruitment programs is…

  14. 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…

  15. Quantum data bus in dipolar coupled nuclear spin qubits

    SciTech Connect

    Zhang Jingfu; Ditty, Michael; Ryan, Colm A.; Laforest, Martin; Moussa, Osama; Baugh, Jonathan; Burgarth, Daniel; Chandrashekar, C. M.; Laflamme, Raymond

    2009-07-15

    We implement an iterative quantum state transfer exploiting the natural dipolar couplings in a spin chain of a liquid-crystal NMR system. During each iteration, a finite part of the amplitude of the state is transferred and, by applying an external operation on only the last two spins, the transferred state is made to accumulate on the spin at the end point. The transfer fidelity reaches one asymptotically through increasing the number of iterations. We also implement the inverted version of the scheme which can transfer an arbitrary state from the end point to any other position of the chain and entangle any pair of spins in the chain, acting as a full quantum data bus.

  16. Application of gravity model on the Korean urban bus network

    NASA Astrophysics Data System (ADS)

    Hong, Inho; Jung, Woo-Sung

    2016-11-01

    Mobility models have been studied to describe the underlying mechanism of human mobility. The mobility patterns in various transportation systems were understood with the gravity model by estimating the traffic as a simple function of population and distance. Compared to most studies on large-scale systems, we focused on the validity and characteristics of gravity model for intraurban mobility. Several variations of gravity model are applied on the urban bus systems of five medium-sized cities in Korea. The gravity model successfully estimates the intraurban traffic without universal exponents for cities. From the change of exponents by predictor types, we figure out the effect by a non-trivial relation between traffic and population in the urban areas.

  17. Error protection capability of space shuttle data bus designs

    NASA Technical Reports Server (NTRS)

    Proch, G. E.

    1974-01-01

    Error protection assurance in the reliability of digital data communications is discussed. The need for error protection on the space shuttle data bus system has been recognized and specified as a hardware requirement. The error protection techniques of particular concern are those designed into the Shuttle Main Engine Interface (MEI) and the Orbiter Multiplex Interface Adapter (MIA). The techniques and circuit design details proposed for these hardware are analyzed in this report to determine their error protection capability. The capability is calculated in terms of the probability of an undetected word error. Calculated results are reported for a noise environment that ranges from the nominal noise level stated in the hardware specifications to burst levels which may occur in extreme or anomalous conditions.

  18. Predictive optimized adaptive PSS in a single machine infinite bus.

    PubMed

    Milla, Freddy; Duarte-Mermoud, Manuel A

    2016-07-01

    Power System Stabilizer (PSS) devices are responsible for providing a damping torque component to generators for reducing fluctuations in the system caused by small perturbations. A Predictive Optimized Adaptive PSS (POA-PSS) to improve the oscillations in a Single Machine Infinite Bus (SMIB) power system is discussed in this paper. POA-PSS provides the optimal design parameters for the classic PSS using an optimization predictive algorithm, which adapts to changes in the inputs of the system. This approach is part of small signal stability analysis, which uses equations in an incremental form around an operating point. Simulation studies on the SMIB power system illustrate that the proposed POA-PSS approach has better performance than the classical PSS. In addition, the effort in the control action of the POA-PSS is much less than that of other approaches considered for comparison.

  19. Characterisation of vibration input to flywheel used on urban bus

    NASA Astrophysics Data System (ADS)

    Wang, L.; Kanarachos, S.; Christensen, J.

    2016-09-01

    Vibration induced from road surface has an impact on the durability and reliability of electrical and mechanical components attached on the vehicle. There is little research published relevant to the durability assessment of a flywheel energy recovery system installed on city and district buses. Relevant international standards and legislations were reviewed and large discrepancy was found among them, in addition, there are no standards exclusively developed for kinetic energy recovery systems on vehicles. This paper describes the experimentation of assessment of road surface vibration input to the flywheel on a bus as obtained at the MIRA Proving Ground. Power density spectra have been developed based on the raw data obtained during the experimentation. Validation of this model will be carried out using accelerated life time tests that will be carried out on a shaker rig using an accumulated profile based on the theory of fatigue damage equivalence in time and frequency domain aligned with the model predictions.

  20. 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.

  1. 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.

  2. Working memory capacity and dual-task interference in picture naming.

    PubMed

    Piai, Vitória; Roelofs, Ardi

    2013-03-01

    Researchers have found no agreement on whether dual-task interference in language performance, such as dual-task interference from tone discrimination on picture naming, reflects passive queuing or active scheduling of processes for each task. According to a passive-queuing account, while a central response-selection bottleneck is occupied by the tone discrimination task, picture naming is held in a passive queue until the bottleneck is freed. In contrast, according to an active-scheduling account, participants determine the order in which the tasks proceed, monitor progress on the tasks, suspend picture naming and hold it in working memory, and determine when to resume picture naming. Here, we report a study that assessed the relative merits of the queuing and scheduling accounts by examining whether the magnitude of dual-task interference in picture naming is associated with individual differences in the capacity of monitoring and updating of working memory representations, as assessed by the operation-span task. We observed that the updating/monitoring ability correlated with the speed of picture naming and with the magnitude of the interference from tone discrimination on picture naming. These results lend support to the active-scheduling account of dual-task interference in picture naming.

  3. Comparison of Parallel and Series Hybrid Power Trains for Transit Bus Applications

    DOE PAGES

    Gao, Zhiming; Daw, C. Stuart; Smith, David E.; LaClair, Tim J.; Parks, James E.; Jones, Perry T.

    2016-08-01

    The fuel economy and emissions of conventional and hybrid buses equipped with emissions after treatment 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 indicated that series hybrid buses have the greatest overall advantage in fuel economy. The series and parallel hybrid buses were predicted to produce similar carbon monoxide and hydrocarbon tailpipe emissions but were also predicted to have reduced tailpipe emissions of nitrogen oxides compared with the conventional bus in higher speed cycles. For the New York bus cycle, which hasmore » the lowest average speed among the cycles evaluated, the series bus tailpipe emissions were somewhat higher than they were for the conventional bus; the parallel hybrid bus had significantly lower tailpipe emissions. All three bus power trains were found to require periodic active diesel particulate filter regeneration to maintain control of particulate matter. Finally, plug-in operation of series hybrid buses appears to offer significant fuel economy benefits and is easily employed because of the relatively large battery capacity that is typical of the series hybrid configuration.« less

  4. 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.

  5. Comparison of Parallel and Series Hybrid Powertrains for Transit Bus Application

    SciTech Connect

    Gao, Zhiming; Daw, C Stuart; Smith, David E; LaClair, Tim J; Parks, II, James E; Jones, Perry T

    2016-01-01

    The fuel economy and emissions of 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 indicated that series hybrid buses have the greatest overall advantage in fuel economy. The series and parallel hybrid buses were predicted to produce similar carbon monoxide and hydrocarbon tailpipe emissions but were also predicted to have reduced tailpipe emissions of nitrogen oxides compared with the conventional bus in higher speed cycles. For the New York bus cycle, 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; the parallel hybrid bus had significantly lower tailpipe emissions. All three bus power trains were found to require periodic active diesel particulate filter regeneration to maintain control of particulate matter. Plug-in operation of series hybrid buses appears to offer significant fuel economy benefits and is easily employed because of the relatively large battery capacity that is typical of the series hybrid configuration.

  6. Comparison of Parallel and Series Hybrid Powertrains for Transit Bus Application

    DOE PAGES

    Gao, Zhiming; Daw, C Stuart; Smith, David E; LaClair, Tim J; Parks, II, James E; Jones, Perry T

    2016-01-01

    The fuel economy and emissions of 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 indicated that series hybrid buses have the greatest overall advantage in fuel economy. The series and parallel hybrid buses were predicted to produce similar carbon monoxide and hydrocarbon tailpipe emissions but were also predicted to have reduced tailpipe emissions of nitrogen oxides compared with the conventional bus in higher speed cycles. For the New York bus cycle, which has themore » lowest average speed among the cycles evaluated, the series bus tailpipe emissions were somewhat higher than they were for the conventional bus; the parallel hybrid bus had significantly lower tailpipe emissions. All three bus power trains were found to require periodic active diesel particulate filter regeneration to maintain control of particulate matter. Plug-in operation of series hybrid buses appears to offer significant fuel economy benefits and is easily employed because of the relatively large battery capacity that is typical of the series hybrid configuration.« less

  7. 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.

  8. 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.

  9. 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.

  10. Urban bus drivers' sleep problems and crash accidents.

    PubMed

    Razmpa, Ebrahim; Sadegh Niat, Khosro; Saedi, Babak

    2011-07-01

    Sleep problems and their direct consequence, sleepiness, results in critical effects on psychomotor skills, memory, decision making, concentration and learning; all of which may play roles in accidents and errors. Despite the importance of quality of sleep among drivers there are only few researches that deal with them. Therefore, we designed this research to better understand possible relationships. This cross-sectional study was performed between 2006 and 2007 among 175 bus drivers of a transportation company in Tehran, the capital of Iran. Participants filled out a questionnaire concerning their demographic and personal history, associated disease, the insomnia index, the Epworth sleepiness scale (ESS), and the apnea index. Then they elaborated their history of crashes. Data was analyzed with the SPSS software through χ(2), Oneway ANOVAs, and Pearson correlation tests. The mean age, and body mass index (BMI) were 43.47 ± 6.85 years and 26.35 ± 3.87 kg/m(2). The mean duration of sleep among these drivers was 6.37 ± 1.62 h per day. The mean accident rate was 2.31 ± 1.83 per year. There was a significant correlation between the insomnia index and BMI (P = 0.014), age (0.00), marital status (0.00), associated disease (0.005), and drug history (0.028). There was a significant relationship between marital status and the ESS, and also between age and accident rate in the past years. Sleep problems were a frequent finding among the studied group and had a significant relationship with their crash history. These results can be an alarming sign to choose bus drivers more carefully and pay more attention to treating their sleep disorders.

  11. Architecture and robustness tradeoffs in speed-scaled queues with application to energy management

    NASA Astrophysics Data System (ADS)

    Dinh, Tuan V.; Andrew, Lachlan L. H.; Nazarathy, Yoni

    2014-08-01

    We consider single-pass, lossless, queueing systems at steady-state subject to Poisson job arrivals at an unknown rate. Service rates are allowed to depend on the number of jobs in the system, up to a fixed maximum, and power consumption is an increasing function of speed. The goal is to control the state dependent service rates such that both energy consumption and delay are kept low. We consider a linear combination of the mean job delay and energy consumption as the performance measure. We examine both the 'architecture' of the system, which we define as a specification of the number of speeds that the system can choose from, and the 'design' of the system, which we define as the actual speeds available. Previous work has illustrated that when the arrival rate is precisely known, there is little benefit in introducing complex (multi-speed) architectures, yet in view of parameter uncertainty, allowing a variable number of speeds improves robustness. We quantify the tradeoffs of architecture specification with respect to robustness, analysing both global robustness and a newly defined measure which we call local robustness.

  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. Multi-server retrial queue with second optional service: algorithmic computation and optimisation

    NASA Astrophysics Data System (ADS)

    Ke, Jau-Chuan; Wu, Chia-Huang; Pearn, Wen Lea

    2011-10-01

    We consider an infinite-capacity M/M/c retrial queue with second optional service (SOS) channel. An arriving customer finds a free server would enter the service (namely, the first essential service, denoted by FES) immediately; otherwise, the customer enters into an orbit and starts generating requests for service in an exponentially distributed time interval until he finds a free server and begins receiving service. After the completion of FES, only some of them receive SOS. The retrial system is modelled by a quasi-birth-and-death process and some system performance measures are derived. The useful formulae for computing the rate matrix and stationary probabilities are derived by means of a matrix-analytic approach. A cost model is derived to determine the optimal values of the number of servers and the two different service rates simultaneously at the minimal total expected cost per unit time. Illustrative numerical examples demonstrate the optimisation approach as well as the effect of various parameters on system performance measures.

  14. A Multi-Objective Compounded Local Mobile Cloud Architecture Using Priority Queues to Process Multiple Jobs.

    PubMed

    Wei, Xiaohui; Sun, Bingyi; Cui, Jiaxu; Xu, Gaochao

    2016-01-01

    As a result of the greatly increased use of mobile devices, the disadvantages of portable devices have gradually begun to emerge. To solve these problems, the use of mobile cloud computing assisted by cloud data centers has been proposed. However, cloud data centers are always very far from the mobile requesters. In this paper, we propose an improved multi-objective local mobile cloud model: Compounded Local Mobile Cloud Architecture with Dynamic Priority Queues (LMCpri). This new architecture could briefly store jobs that arrive simultaneously at the cloudlet in different priority positions according to the result of auction processing, and then execute partitioning tasks on capable helpers. In the Scheduling Module, NSGA-II is employed as the scheduling algorithm to shorten processing time and decrease requester cost relative to PSO and sequential scheduling. The simulation results show that the number of iteration times that is defined to 30 is the best choice of the system. In addition, comparing with LMCque, LMCpri is able to effectively accommodate a requester who would like his job to be executed in advance and shorten execution time. Finally, we make a comparing experiment between LMCpri and cloud assisting architecture, and the results reveal that LMCpri presents a better performance advantage than cloud assisting architecture. PMID:27419854

  15. A Multi-Objective Compounded Local Mobile Cloud Architecture Using Priority Queues to Process Multiple Jobs.

    PubMed

    Wei, Xiaohui; Sun, Bingyi; Cui, Jiaxu; Xu, Gaochao

    2016-01-01

    As a result of the greatly increased use of mobile devices, the disadvantages of portable devices have gradually begun to emerge. To solve these problems, the use of mobile cloud computing assisted by cloud data centers has been proposed. However, cloud data centers are always very far from the mobile requesters. In this paper, we propose an improved multi-objective local mobile cloud model: Compounded Local Mobile Cloud Architecture with Dynamic Priority Queues (LMCpri). This new architecture could briefly store jobs that arrive simultaneously at the cloudlet in different priority positions according to the result of auction processing, and then execute partitioning tasks on capable helpers. In the Scheduling Module, NSGA-II is employed as the scheduling algorithm to shorten processing time and decrease requester cost relative to PSO and sequential scheduling. The simulation results show that the number of iteration times that is defined to 30 is the best choice of the system. In addition, comparing with LMCque, LMCpri is able to effectively accommodate a requester who would like his job to be executed in advance and shorten execution time. Finally, we make a comparing experiment between LMCpri and cloud assisting architecture, and the results reveal that LMCpri presents a better performance advantage than cloud assisting architecture.

  16. Digitalized K(+) Occupancy in the Nanocavity Holds and Releases Queues of K(+) in a Channel.

    PubMed

    Sumikama, Takashi; Oiki, Shigetoshi

    2016-08-17

    The mechanisms of ion permeation through potassium channels have been extensively examined. Molecular dynamics (MD) simulations have demonstrated that rapidly permeating ions collide near the selectivity filter (SF) ("knock-on" mechanism), but this oversimplified mechanism is insufficient to account for the experimentally observed single-channel current amplitudes. Here, we analyzed the MD-simulated ion trajectories through a Kv1.2 potassium channel using an event-oriented analysis method, and surprisingly, we found that the nanocavity (NC) governs ion permeation in a digital fashion. The NC has a maximal diameter of 10 Å and stands between the intracellular bulk solution and the SF, which holds only up to one K(+) during permeation. Accordingly, the K(+) concentration in the intracellular solution is translated as a digitalized zero or one K(+) in the NC. When the ion number in the NC is zero, the multiple ions in the SF are mostly immobilized. By contrast, when the number of ions in the NC is one, the structured water in the NC mediates the ion-occupied status to the queueing ions in the SF, and the ions then initiate a collective outward motion. Accordingly, the one ion in the NC serves as a catalytic intermediate for permeation, which quantitatively accounts for the experimentally obtained conductance-concentration relationships. We conclude that the ion movements are coherent across the entire pore. PMID:27454924

  17. A Multi-Objective Compounded Local Mobile Cloud Architecture Using Priority Queues to Process Multiple Jobs

    PubMed Central

    Wei, Xiaohui; Sun, Bingyi; Cui, Jiaxu; Xu, Gaochao

    2016-01-01

    As a result of the greatly increased use of mobile devices, the disadvantages of portable devices have gradually begun to emerge. To solve these problems, the use of mobile cloud computing assisted by cloud data centers has been proposed. However, cloud data centers are always very far from the mobile requesters. In this paper, we propose an improved multi-objective local mobile cloud model: Compounded Local Mobile Cloud Architecture with Dynamic Priority Queues (LMCpri). This new architecture could briefly store jobs that arrive simultaneously at the cloudlet in different priority positions according to the result of auction processing, and then execute partitioning tasks on capable helpers. In the Scheduling Module, NSGA-II is employed as the scheduling algorithm to shorten processing time and decrease requester cost relative to PSO and sequential scheduling. The simulation results show that the number of iteration times that is defined to 30 is the best choice of the system. In addition, comparing with LMCque, LMCpri is able to effectively accommodate a requester who would like his job to be executed in advance and shorten execution time. Finally, we make a comparing experiment between LMCpri and cloud assisting architecture, and the results reveal that LMCpri presents a better performance advantage than cloud assisting architecture. PMID:27419854

  18. First passage times in M2[X ]|G |1 |R queue with hysteretic overload control policy

    NASA Astrophysics Data System (ADS)

    Pechinkin, Alexander V.; Razumchik, Rostislav R.; Zaryadov, Ivan S.

    2016-06-01

    One of the reported approaches towards the solution of overload problem in networks of SIP servers is the implementation of multi-level hysteretic control of arrivals in SIP servers. Each level, being the parameter of the policy, specifies operation mode of SIP server i.e. it implicitly indicates what SIP server must do with the arriving packets. The choice of parameters' values is not guided by standards and is usually left for the network owner. In general, all operation modes of the considered policy can be grouped into two groups: normal mode (when all arriving packets are accepted) and congested mode (when part or all arriving packets are being dropped). Such grouping may serve as the criteria for choosing parameters' values of the policy: pick those values which minimize SIP server sojourn time in congested mode. In this short note we propose some analytical results which facilitate the solution of stated minimization problem. The considered mathematical model of SIP server is the queueing system M2[X ]|G |1 |R with batch arrivals and bi-level hysteretic control policy, which specifies three operation modes: normal (customers both flows are accepted), overload (only customers from one flow are accepted), discard (customers from both flows are blocked/lost)). The switching between modes can occur only on service completions. Analytical method allowing computation of stationary sojourn times in different operation modes (as well as first passage times between modes) is presented in brief. Numerical example is given.

  19. 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.

  20. Design of the HEAO main bus shunt regulator. [High Energy Astronomical Observatory solar array

    NASA Technical Reports Server (NTRS)

    Middlebrook, R. D.; Kimble, S. G.

    1976-01-01

    The High Energy Astronomy Observatory (HEAO) is being built for NASA by an American company. The general requirements concerning the HEAO main bus regulator are examined. The bus regulated voltage is 33 V, the maximum shunt current is 45 A, and the regulator output impedance is to be less than 0.5 Ohm from dc to 100 kHz. Loop gain design considerations for the main bus regulator are discussed and a description is given of the general device configuration. Attention is also given to regulator loop design and performance.

  1. 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.

  2. 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…

  3. Dual stage passive vibration isolation for optical interferometer missions

    NASA Astrophysics Data System (ADS)

    Bronowicki, Allen J.; MacDonald, Rhonda; Gürsel, Yekta; Goullioud, Renaud; Neville, Timothy; Platus, David L.

    2003-02-01

    Future space-based optical instruments such as the Space Interferometer Mission have vibration-induced error allocations at the levels of a few nano-meters and milli-arc-seconds. A dual stage passive isolation approach has been proposed using isolation first at the vibration-inducing reaction wheels, and a second isolation layer between the bus portion of the space vehicle (the backpack) and the optical payload. The development of the backpack isolator is described, with unit transmissibility results for individual isolator struts. The dual stage isolation approach is demonstrated on a dynamically feature-rich, 7-meter structural testbed (STB3). A new passive suspension that mitigates ground vibrations above 0.4 Hz has been integrated into the testbed. A series of OPD performance predictions have been made using measured transfer functions. These indicate that the 5-nm dynamic OPD allocation is within reach using the dual isolator approach. Demonstrating these low response levels in a noisy air environment has proven to be difficult. We are sequentially executing a plan to mitigate acoustic transmission between backpack and flight structure, as well as developing techniques to mitigate effects of background acoustic noise.

  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. Design the developed bus parking area management solution based on fusion technology of things

    NASA Astrophysics Data System (ADS)

    Ge, Ying-long

    2013-07-01

    Taking advantage of the fusion technology of things this paper constructed a combination of hardware and software application, hardware's major function was to collect the bus behavior data of system needed, including basic data of driver and fare bag stored in moving passive RFID tag, and the information of running status of bus on each stage perceived by all kinds of sensors in the parking area. The information which was handled by the middleware was sent to data center. The program solved the problem on the monitoring of the behavior of the bus in the parking area, meanwhile, achieved the data sharing, so as to tackle the defects of the traditional bus parking area management system's non-automated data collection, non-real-time data presenting and poor data sharing.

  6. Annoyance evaluation and the effect of noise on the health of bus drivers.

    PubMed

    Bruno, Portela S; Marcos, Queiroga R; Amanda, Constantini; Paulo, Zannin H T

    2013-01-01

    In the present study, we evaluated annoyance and the effects of noise on the health of bus drivers. For that, 200 bus drivers from a public transport company participated in a cross-sectional study. Annoyance and effects on health was measured with analog scale: Sleep quality, occurrence of tinnitus, headache, irritation, and annoyance from bus engine, traffic, and passengers. Data of age and working time of bus drivers also were obtained. For noise exposure, LA eq was evaluated in 80 buses. Statistical analysis consisted of mean, standard deviation, minimum, and maximum, Kruskal-Wallis test with post-hoc Dunn, one-way ANOVA with post-hoc Tukey and Spearman's correlation coefficient. Results indicate three groups of bus drivers (not annoyed: (N.A.), a little annoyed (L.A.) and highly annoyed (H.A.)). The group H.A. was younger and with less working time in relation to others, with a significant difference only for age. Regarding sleep quality, there was no significant difference. For results on the occurrence of tinnitus, headache and irritation after work, group H.A. had significantly higher means. Result of annoyance to the bus engine was significantly higher in H.A. than in L.A. and N.A. Annoyance to traffic and passengers, no significant differences were found, but the highest results were found for L.A., followed by H.A. and N.A. Equivalent sound pressure level in buses was above of the limit for occupational comfort. It was concluded that bus drivers has considerable level of noise annoyance and some health effects are perceived. The noise is a factor discomfort ergonomic that may cause effects on health of bus drivers. This study aims to evaluate annoyance and the effects of noise on the health of bus drivers. Cross-sectional study with buses and bus drivers. For that, 200 bus drivers from a public transport company participated in a cross-sectional study. Annoyance and effects on health was measured with analog scale: Sleep quality, occurrence of tinnitus

  7. [On road particle emission characteristics of a Chinese phase IV natural gas bus].

    PubMed

    Lou, Di-Ming; Cheng, Wei; Feng, Qian

    2014-03-01

    An on-road experimental research was made on a Chinese phase IV natural gas bus using a Portable Emission Measurement System (PEMS), and particle emission characteristics under different vehicle speed, acceleration and vehicle specific power were investigated. The results show that particle number and mass emission rates increase and their emission factors decrease while the speed of the bus rises. Particle number concentration of different sizes shows multimodal logarithmic distribution pattern when the bus runs on all operation conditions (idle, low speed, medium speed and high speed), and nucleation mode particle account for a large proportion in the total particle number. With the increase of acceleration, particle emission rate rises, and it is lower when the bus runs at constant speed or slow deceleration condition than that at the fast acceleration condition. Furthermore, particle emission rate increases against the absolute value of the vehicle specific power (VSP).

  8. Constant of thermal heat conduction and stabilization of the bus bar conductor for superconducting accelerators

    SciTech Connect

    Lopez, G.

    1993-07-01

    Using the one-dimensional, time-independent conduction state, a constant of thermal heating conduction is given that brings about the known stabilization theorem and a closed expression for the bus bar to be cryogenically stable in superconducting accelerators.

  9. 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.

  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. Annoyance evaluation and the effect of noise on the health of bus drivers.

    PubMed

    Bruno, Portela S; Marcos, Queiroga R; Amanda, Constantini; Paulo, Zannin H T

    2013-01-01

    In the present study, we evaluated annoyance and the effects of noise on the health of bus drivers. For that, 200 bus drivers from a public transport company participated in a cross-sectional study. Annoyance and effects on health was measured with analog scale: Sleep quality, occurrence of tinnitus, headache, irritation, and annoyance from bus engine, traffic, and passengers. Data of age and working time of bus drivers also were obtained. For noise exposure, LA eq was evaluated in 80 buses. Statistical analysis consisted of mean, standard deviation, minimum, and maximum, Kruskal-Wallis test with post-hoc Dunn, one-way ANOVA with post-hoc Tukey and Spearman's correlation coefficient. Results indicate three groups of bus drivers (not annoyed: (N.A.), a little annoyed (L.A.) and highly annoyed (H.A.)). The group H.A. was younger and with less working time in relation to others, with a significant difference only for age. Regarding sleep quality, there was no significant difference. For results on the occurrence of tinnitus, headache and irritation after work, group H.A. had significantly higher means. Result of annoyance to the bus engine was significantly higher in H.A. than in L.A. and N.A. Annoyance to traffic and passengers, no significant differences were found, but the highest results were found for L.A., followed by H.A. and N.A. Equivalent sound pressure level in buses was above of the limit for occupational comfort. It was concluded that bus drivers has considerable level of noise annoyance and some health effects are perceived. The noise is a factor discomfort ergonomic that may cause effects on health of bus drivers. This study aims to evaluate annoyance and the effects of noise on the health of bus drivers. Cross-sectional study with buses and bus drivers. For that, 200 bus drivers from a public transport company participated in a cross-sectional study. Annoyance and effects on health was measured with analog scale: Sleep quality, occurrence of tinnitus

  12. 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.

  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. ConnectX2 In niBand Management Queues: New support for Network Of oaded

    SciTech Connect

    Graham, Richard L; Poole, Stephen W; Shamis, Pavel; Bloch, Gil; Bloch, Noam; Kagan, Michael; Rabinovitz, Ishai; Shainer, Gilad

    2010-01-01

    This paper introduces the newly developed InfiniBand (IB) Management Queue capability, used by the Host Channel Adapter (HCA) to manage network task data flow dependancies, and progress the communications associated with such flows. These tasks include sends, receives, and the newly supported wait task, and are scheduled by the HCA based on a data dependency description provided by the user. This functionality is supported by the ConnectX-2 HCA, and provides the means for delegating collective communication management and progress to the HCA, also known as collective communication offload. This provides a means for overlapping collective communications managed by the HCA and computation on the Central Processing Unit (CPU), thus making it possible to reduce the impact of system noise on parallel applications using collective operations. This paper further describes how this new capability can be used to implement scalable Message Passing Interface (MPI) collective operations, describing the high level details of how this new capability is used to implement the MPI Barrier collective operation, focusing on the latency sensitive performance aspects of this new capability. This paper concludes with small scale benchmark experiments comparing implementations of the barrier collective operation, using the new network offload capabilities, with established point-to-point based implementations of these same algorithms, which manage the data flow using the central processing unit. These early results demonstrate the promise this new capability provides to improve the scalability of high-performance applications using collective communications. The latency of the HCA based implementation of the barrier is similar to that of the best performing point-to-point based implementation managed by the central processing unit, starting to outperform these as the number of processes involved in the collective operation increases.

  15. 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.

  16. Tunable filter and optical buffer based on dual plasmonic ring resonators

    NASA Astrophysics Data System (ADS)

    Li, Boxun; Li, Hongjian; Zeng, Lili; Zhan, Shiping; Cao, Guangtao; He, Zhihui; Yang, Hui

    2015-02-01

    We demonstrate the realization of on chip plasmon-induced transparency using dual ring resonators coupling to metal-dielectric-metal bus waveguide. The theoretical results agree well with the finite-difference time-domain simulative ones. Moreover, by adjusting the radius, width, as well as the coupling distance can efficiently operate the wavelengths and bandwidths of our filter. In theory, we propose a feasible method to improve the trade-off between transmission and quality factor. Finally, the ultra-compact structure possesses slow light effect and manifests a low group velocity, which provides a guideline to control the light and has potential application in optical filter and optical buffer.

  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. 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.

  19. Factors associated with self-reported driver sleepiness and incidents in city bus drivers.

    PubMed

    Anund, Anna; Ihlström, Jonas; Fors, Carina; Kecklund, Göran; Filtness, Ashleigh

    2016-08-01

    Driver fatigue has received increased attention during recent years and is now considered to be a major contributor to approximately 15-30% of all crashes. However, little is known about fatigue in city bus drivers. It is hypothesized that city bus drivers suffer from sleepiness, which is due to a combination of working conditions, lack of health and reduced sleep quantity and quality. The overall aim with the current study is to investigate if severe driver sleepiness, as indicated by subjective reports of having to fight sleep while driving, is a problem for city based bus drivers in Sweden and if so, to identify the determinants related to working conditions, health and sleep which contribute towards this. The results indicate that driver sleepiness is a problem for city bus drivers, with 19% having to fight to stay awake while driving the bus 2-3 times each week or more and nearly half experiencing this at least 2-4 times per month. In conclusion, severe sleepiness, as indicated by having to fight sleep during driving, was common among the city bus drivers. Severe sleepiness correlated with fatigue related safety risks, such as near crashes.

  20. Factors associated with self-reported driver sleepiness and incidents in city bus drivers

    PubMed Central

    ANUND, Anna; IHLSTRÖM, Jonas; FORS, Carina; KECKLUND, Göran; FILTNESS, Ashleigh

    2016-01-01

    Driver fatigue has received increased attention during recent years and is now considered to be a major contributor to approximately 15–30% of all crashes. However, little is known about fatigue in city bus drivers. It is hypothesized that city bus drivers suffer from sleepiness, which is due to a combination of working conditions, lack of health and reduced sleep quantity and quality. The overall aim with the current study is to investigate if severe driver sleepiness, as indicated by subjective reports of having to fight sleep while driving, is a problem for city based bus drivers in Sweden and if so, to identify the determinants related to working conditions, health and sleep which contribute towards this. The results indicate that driver sleepiness is a problem for city bus drivers, with 19% having to fight to stay awake while driving the bus 2–3 times each week or more and nearly half experiencing this at least 2–4 times per month. In conclusion, severe sleepiness, as indicated by having to fight sleep during driving, was common among the city bus drivers. Severe sleepiness correlated with fatigue related safety risks, such as near crashes. PMID:27098307

  1. An observational comparison of the older and younger bus passenger experience in a developing world city.

    PubMed

    Aceves-González, Carlos; May, Andrew; Cook, Sharon

    2016-06-01

    This study was an unobtrusive observational analysis of 333 older and younger bus passengers in Guadalajara, Mexico. A set of data were collected for each observed passenger, as well as more general observations related to driver behaviour, bus design and bus service characteristics. There were significant differences between older and younger passengers in terms of boarding and alighting times, use of handrails, seat location preferences, passenger stability and coping strategies in order to maintain postural stability. The conditions of travel are conducive to a poor passenger experience for the older passengers in particular. Although the problems may be attributed to bus design and driver behaviour typical of that in developing countries, they are also influenced by the wider transport infrastructure, and a lack of a regulatory regime which places drivers under time pressure and in direct competition with each other. Practitioner Summary: Bus services must cater for all ages of passengers, including the elderly. This unobtrusive observational study investigated the passenger experience in a developing world city. Bus and wider service design were found to compromise the journey experience, with the older users being particularly negatively impacted. Design recommendations are provided.

  2. 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.

  3. Feasibility study of logic circuits with a spin wave bus.

    PubMed

    Khitun, Alexander; Nikonov, Dmitri E; Bao, Mingqiang; Galatsis, Kosmas; Wang, Kang L

    2007-11-21

    We present a feasibility study of logic circuits utilizing spin waves for information transmission and processing. As an alternative approach to the transistor-based architecture, logic circuits with a spin wave bus do not use charge as an information carrier. In this work we describe the general concept of logic circuits with a spin wave bus and illustrate its performance by numerical simulations based on available experimental data. Theoretical estimates and results of numerical simulations on signal attenuation, signal phase velocity, and the minimum spin wave energy required per bit in the spin bus are obtained. The transport parameters are compared with ones for conventional electronic transmission lines. The spin wave bus is not intended to substitute traditional metal interconnects since it has higher signal attenuation and lower signal propagation speed. The potential value of a spin wave bus is, however, an interface between electronic circuits and integrated spintronics circuits. The logic circuits with a spin wave bus allow us to provide wireless read-in and read-out.

  4. 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

  5. Blood pressure and blood lead concentration in bus drivers.

    PubMed Central

    Sharp, D S; Osterloh, J; Becker, C E; Bernard, B; Smith, A H; Fisher, J M; Syme, S L; Holman, B L; Johnston, T

    1988-01-01

    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 pressures varied from 102 to 173 mm Hg and from 61 to 105 mm Hg, respectively. The blood lead concentration varied from 2 to 15 micrograms/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 (micrograms/dL) [90% C. I., -1.6, 5.3]. The coefficient for diastolic blood pressure was 2.5 mm Hg/ln (micrograms/dL) [90% C. I., 0.1, 4.9]. 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. PMID:3203632

  6. 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.

  7. 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.

  8. Bus development for a multitask engineering test satellite: SATEX

    NASA Astrophysics Data System (ADS)

    Peralta-Fabi, Ricardo; Mendieta-Jiminez, J.; Prado, Jorge M.; Peralta, Armando; Navarrete, Margarita; Fairuzov, Y.

    1993-09-01

    Multitask bus for small satellites is being developed at the University of Mexico (UNAM) for the conduction of LEO communications, remote sensing, and astronomical missions. The first prototype, SATEX-1, to be launched by Ariane in mid 1994, is a 50 Kg engineering test satellite with a primary communications payload and a CCD camera for low resolution imaging, as a secondary payload. SATEX-1 has been under design and development for several years and will be constructed by several research institutions, under finance from the Ministry of Communications (SCT/IMC). The structure is made of hybrid materials, including light aluminum alloys and composites. It has a three axis stabilization system. Attitude detection is realized by means of several sun and earth sensors. Electrical power is collected by two solar panels that are stowed for take-off, and deployed after separation. Thermal design is based mostly on passive components including radiators, shielding and orientation, but flat heaters are used in several places. Solid-state temperature sensors are used throughout the s/c to test and calibrate thermal models.

  9. Effects of biodiesel on emissions of a bus diesel engine.

    PubMed

    Kegl, Breda

    2008-03-01

    This paper discusses the influence of biodiesel on the injection, spray, and engine characteristics with the aim to reduce harmful emissions. The considered engine is a bus diesel engine with injection M system. The injection, fuel spray, and engine characteristics, obtained with biodiesel, are compared to those obtained with mineral diesel (D2) under various operating regimes. The considered fuel is neat biodiesel from rapeseed oil. Its density, viscosity, surface tension, and sound velocity are determined experimentally and compared to those of D2. The obtained results are used to analyze the most important injection, fuel spray, and engine characteristics. The injection characteristics are determined numerically under the operating regimes, corresponding to the 13 mode ESC test. The fuel spray is obtained experimentally under peak torque condition. Engine characteristics are determined experimentally under 13 mode ESC test conditions. The results indicate that, by using biodiesel, harmful emissions (NO(x), CO, smoke and HC) can be reduced to some extent by adjusting the injection pump timing properly. PMID:17350250

  10. 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.

  11. 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.

  12. Bus use and older people: a literature review applying the Person-Environment-Occupation model in macro practice.

    PubMed

    Broome, Kieran; McKenna, Kryss; Fleming, Jennifer; Worrall, Linda

    2009-03-01

    The same reasons that prompt older people to give up driving can also result in difficulties with accessing public transport. Difficulties using public transport can limit older people's participation in society, thereby impacting negatively on their health. Focusing on public buses, this review explicates the link between bus usability and the health of older people and frames existing evidence on bus usability issues. The Person-Environment-Occupation (PEO) model offers a framework by which bus usability can be assessed. A combination of person-centred, environmental, and occupation-related factors, including bus design, service provision and performance, information, and the attitudes of staff and the community, impact on older people's ability to catch buses. More systematic research needs to take place in order to develop a comprehensive understanding of bus usability. Occupational therapy has a key role to play in conceptualizing, implementing, and evaluating improvements in bus usability for older people. PMID:18777441

  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. 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

  15. Increased urinary 8-hydroxy-2'-deoxyguanosine excretion in long-distance bus drivers in Taiwan.

    PubMed

    Han, Yueh-Ying; Donovan, Maryann; Sung, Fung-Chang

    2010-05-01

    Professional bus drivers are exposed to environments containing air pollution and reactive oxygen species (ROS) that can induce cellular oxidative stress and DNA damage. This study investigated environmental factors associated with oxidative DNA damage in a cohort of long-distance bus drivers. In a comparison study, urinary 8-hydroxydeoxyguanosine (8-OHdG), a biomarker of DNA oxidative damage, was examined in 120 male long-distance bus drivers and 58 male office workers in Taiwan. Multivariate logistic regression was used to analyze association between urinary 8-OHdG levels and environmental factors. Bus drivers had higher urinary 8-OHdG levels (adjusted odds ratio (aOR)=9.4, 95% confidence interval (CI)=3.5-28.2) compared with office workers. Increased urinary 8-OHdG level was significantly related to cigarette smoking (aOR=18.0, 95% CI=7.1-52.1), consumption of energy drinks (aOR=5.0, 95% CI=2.1-12.6), and regular exercise (aOR=3.8, 95% CI=1.5-10.2). A strong exposure-response relationship was found between urinary 8-OHdG and urinary cotinine (p<0.0001). Among nonsmokers, bus drivers (aOR=3.9, 95% CI=1.0-17.7) had higher urinary 8-OHdG than office workers. Among both bus drivers and office workers, those who drank energy drinks (aOR=3.7, 95% CI=1.2-12.2) had higher 8-OHdG levels than those who did not drink energy drinks. Adjusted for smoking, levels of 8-OHdG were increased in long-distance bus drivers exposed to traffic exhaust and ingested energy drinks. Future studies should explore what aspects of energy drinks may contribute to increased urinary 8-OHdG.

  16. 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.

  17. 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.

  18. 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.

  19. Dual-Mode Combustor

    NASA Technical Reports Server (NTRS)

    Trefny, Charles J (Inventor); Dippold, Vance F (Inventor)

    2013-01-01

    A new dual-mode ramjet combustor used for operation over a wide flight Mach number range is described. Subsonic combustion mode is usable to lower flight Mach numbers than current dual-mode scramjets. High speed mode is characterized by supersonic combustion in a free-jet that traverses the subsonic combustion chamber to a variable nozzle throat. Although a variable combustor exit aperture is required, the need for fuel staging to accommodate the combustion process is eliminated. Local heating from shock-boundary-layer interactions on combustor walls is also eliminated.

  20. Dual Species NMR Oscillator

    NASA Astrophysics Data System (ADS)

    Weber, Joshua; Korver, Anna; Thrasher, Daniel; Walker, Thad

    2016-05-01

    We present progress towards a dual species nuclear magnetic oscillator using synchronous spin exchange optical pumping. By applying the bias field as a sequence of alkali 2 π pulses, we generate alkali polarization transverse to the bias field. The alkali polarization is then modulated at the noble gas resonance so that through spin exchange collisions the noble gas becomes polarized. This novel method of NMR suppresses the alkali field frequency shift by at least a factor of 2500 as compared to longitudinal NMR. We will present details of the apparatus and measurements of dual species co-magnetometry using this method. Research supported by the NSF and Northrop-Grumman Corp.