Full Text Available Engineering qualification model payload for a communications and broadcasting satellite(CBS was developed by ETRI from May, 2000 to April, 2003. For the purpose of functional test and verification of the payload, a real-time hardware-in-the-loop(HITL CBS simulator(CBSSIM was also developed. We assumed that the spacecraft platform for the CBSSIM is a geostationary communication satellite using momentum bias three-axis stabilization control technique based on Koreasat. The payload hardware is combined with CBSSIM via Power, Command and Telemetry System(PCTS of Electrical Ground Support Equipment(EGSE. CBSSIM is connected with PCTS by TCP/IP and the payload is combined with PCTS by MIL-STD-1553B protocol and DC harness. This simulator runs under the PC-based simulation environment with Windows 2000 operating system. The satellite commands from the operators are transferred to the payload or bus subsystem models through the real-time process block in the simulator. Design requirements of the CBSSIM are to operate in real-time and generate telemetry. CBSSIM provides various graphic monitoring interfaces and control functions and supports both pre-launch and after-launch of a communication satellite system. In this paper, the HITL simulator system including CBSSIM, communications payload and PCTS as the medium of interface between CBSSIM and communications payload will be described in aspects of the system architecture, spacecraft models, and simulator operation environment.
Halpin, S. M.; Grigsby, L. L.; Sheble, G. B.; Nelms, R. M.
The problems in applying standard electric utility models, analyses, and algorithms to the study of the stability of spacecraft power conditioning and distribution systems are discussed. Both single-phase and three-phase systems are considered. Of particular concern are the load and generator models that are used in terrestrial power system studies, as well as the standard assumptions of load and topological balance that lead to the use of the positive sequence network. The standard assumptions regarding relative speeds of subsystem dynamic responses that are made in the classical transient stability algorithm, which forms the backbone of utility-based studies, are examined. The applicability of these assumptions to a spacecraft power system stability study is discussed in detail. In addition to the classical indirect method, the applicability of Liapunov's direct methods to the stability determination of spacecraft power systems is discussed. It is pointed out that while the proposed method uses a solution process similar to the classical algorithm, the models used for the sources, loads, and networks are, in general, more accurate. Some preliminary results are given for a linear-graph, state-variable-based modeling approach to the study of the stability of space-based power distribution networks.
Anderson, D. J.; Munk, M. M.; Pencil, E.; Dankanich, J.; Glaab, L.; Peterson, T.
The In-Space Propulsion Technology (ISPT) program is developing spacecraft bus and platform technologies that will enable or enhance NASA robotic science missions. The ISPT program is currently developing technology in four areas that include Propulsion System Technologies (electric and chemical), Entry Vehicle Technologies (aerocapture and Earth entry vehicles), Spacecraft Bus and Sample Return Propulsion Technologies (components and ascent vehicles), and Systems/Mission Analysis. Three technologies are ready for near-term flight infusion: 1) the high-temperature Advanced Material Bipropellant Rocket (AMBR) engine providing higher performance; 2) NASA's Evolutionary Xenon Thruster (NEXT) ion propulsion system, a 0.6-7 kW throttle-able gridded ion system; and 3) Aerocapture technology development with investments in a family of thermal protection system (TPS) materials and structures; guidance, navigation, and control (GN& C) models of blunt-body rigid aeroshells; and aerothermal effect models. Two component technologies being developed with flight infusion in mind are the Advanced Xenon Flow Control System and ultra-lightweight propellant tank technologies. Future directions for ISPT are technologies that relate to sample return missions and other spacecraft bus technology needs like: 1) Mars Ascent Vehicles (MAV); 2) multi-mission technologies for Earth Entry Vehicles (MMEEV); and 3) electric propulsion. These technologies are more vehicles and mission-focused, and present a different set of technology development and infusion steps beyond those previously implemented. The Systems/Mission Analysis area is focused on developing tools and assessing the application of propulsion and spacecraft bus technologies to a wide variety of mission concepts. These in-space propulsion technologies are applicable, and potentially enabling for future NASA Discovery, New Frontiers, and sample return missions currently under consideration, as well as having broad applicabilit- to
Anderson, David; Pencil, Eric J.; Glaab, Louis; Falck, Robert D.; Dankanich, John
NASA's In-Space Propulsion Technology (ISPT) program has been developing technologies for lowering the cost of planetary science missions. The technology areas include electric propulsion technologies, spacecraft bus technologies, entry vehicle technologies, and design tools for systems analysis and mission trajectories. The electric propulsion technologies include critical components of both gridded and non-gridded ion propulsion systems. The spacecraft bus technologies under development include an ultra-lightweight tank (ULTT) and advanced xenon feed system (AXFS). The entry vehicle technologies include the development of a multi-mission entry vehicle, mission design tools and aerocapture. The design tools under development include system analysis tools and mission trajectory design tools.
Antipov Kirill A.
Full Text Available The paper deals with spacecraft in the circular near-Earth orbit. The spacecraft interacts with geomagnetic field by the moments of Lorentz and magnetic forces. The octupole approximation of the Earth’s magnetic field is accepted. The spacecraft electromagnetic parameters, namely the electrostatic charge moment of the first order and the eigen magnetic moment are the controlled quasiperiodic functions. The control algorithms for the spacecraft electromagnetic parameters, which allows to stabilize the spacecraft attitude position in the orbital frame are obtained. The stability of the spacecraft stabilized orientation is proved both analytically and by PC computations.
Full Text Available Several online methods were proposed for investigating the voltage stability condition of an interconnected power system using the measurements of voltage and current phasors at a bus. For this purpose, phasor measurement units (PMUs are used. A PMU is a device which measures the electrical waves on an electrical network, using a common time source (reference bus for synchronisation. This study proposes a method for online monitoring of voltage stability condition of a power system using measurements of bus variables namely – (i real power, (ii reactive power and (iii bus voltage magnitude at a bus. The measurements of real power, reactive power and bus voltage magnitude could be extracted/captured from a smart energy meter. The financial involvement for implementation of the proposed method would significantly lower compared with the PMU-based method.
National Aeronautics and Space Administration — The objective of my proposal is to determine the stability of a spacecraft when in the vicinity of an asteroid. Orbiting an asteroid is a difficult task. The unique...
Full Text Available The improvement of transient stability of power system was one of the most challenging research areas in power engineer.The main aim of this paper was transient stability analysis and improvement of IEEE 9 bus system. These studies were computed using POWER WORLD SIMULATOR. The IEEE 9 bus system was modelled in power world simulator and load flow studies were performed to determine pre-fault conditions in the system using Newton-Raphson method. The transient stability analysis was carried out using Runga method during three-phase balanced fault. For the improvement transient stability, the general methods adopted were fast acting exciters, FACT devices and addition of parallel transmission line. These techniques play an important role in improving the transient stability, increasing transmission capacity and damping low frequency oscillations.
Clark, C. S.; Lopez Mazarias, A.; Kobayashi, C.; Nakasuka, S.
There is considerable interest in the benefits of having a modular spacecraft where it is possible to construct a satellite using a number of modules with identical mechanical and electrical interfaces, but with each performing a specific function to achieve the required platform specification. In recent years, steps have been made towards modular spacecraft becoming a reality and the concept is due to be demonstrated in-orbit later this year with the first flight of the PETSAT spacecraft concept on the mission, SOHLA-2. This paper describes the approach to the design of the SOHLA-2 power system. The approach is significant; PETSAT is an excellent example of a modular approach to spacecraft design. The PETSAT concept consists of a number of 'Panel Modules', roughly the same size as a pizza box. The panels stack together in stowed configuration for launch, and unfold once in orbit. Apart from being a very novel approach to spacecraft design and construction, this concept offers advantages in power generation as, once unfolded, there is significant surface area on which to mount solar cells for power generation. The power system for PETSAT has been designed such that each Panel Module contains a power system that can either operate in isolation for the purpose of unit testing, or as part of a larger spacecraft power system once connected to other Panel Modules. When connected together, the power systems on each module share the energy from the solar arrays and the batteries. The approach to the design of the system has provided a simple solution to difficult problem.
Zhang, Ni; Liu, Hai-mei; Bei, Shao-yi; Li, Bo; Zhao, Jing-bo
Electric hydraulic assist force steering system (EHPS system) is the steering system of electric bus, this paper presents a method of EHPS handling stability analysis based on system identification method according to the handling stability of EHPS system for electric bus. The simulation model of electro-hydraulic assist force steering system EHPS is established by using the software AMESim, and making a quantitative analysis on the characteristics of the electric assist force assisted steering system, the assist force response and stability. At the same time, we study the stability of vehicle, including hunting, transient response, return experiment, the results show that the HPS and EHPS by comparing the simulation: It improves the portability, road sense, transient response and return performance after loading the system, which verifiy the effectiveness of the control strategy that improves vehicle steering performance, and it provides the basis for the optimization of control methods in the future.
Y. G. Panamarenka
Full Text Available A numerical method for calculation of open-air substations’ flexible bus-bars dynamic at short-circuit has been improved on equations of a flexible elastic string with application of an implicit scheme. On the basis of the numerical method a computer program FLEBUS for calculation of substations’ flexible bus-bars dynamic at short-circuit has been developed. An approbation and an estimation of calculation result reliability have been carried out in accordance with the program while using experimental data. On the basis of the obtained information it is possible to assert that the developed program is an independent tool for calculation of electrodynamic stability of substations’ flexible bus-bars.
Full Text Available The robust optimal attitude control problem for a flexible spacecraft is considered. Two optimal sliding mode control laws that ensure the exponential convergence of the attitude control system are developed. Integral sliding mode control (ISMC is applied to combine the first-order sliding mode with optimal control and is used to control quaternion-based spacecraft attitude manoeuvres with external disturbances and an uncertainty inertia matrix. For the optimal control part the state-dependent Riccati equation (SDRE and optimal Lyapunov techniques are employed to solve the infinite-time nonlinear optimal control problem. The second method of Lyapunov is used to guarantee the stability of the attitude control system under the action of the proposed control laws. An example of multiaxial attitude manoeuvres is presented and simulation results are included to verify the usefulness of the developed controllers.
Singh, Sahjendra N.
A control law for three-axis rotational maneuvers of a spacecraft beam-tip body configuration based on non-linear inversion and modal velocity feedback is presented. A decoupling attitude control law is presented such that in the closed-loop system the attitude angles of the spacecraft are independently controlled, using the control moments acting on the space vehicle. This controller asymptotically decouples the flexible dynamics from the rigid one and also allows the decomposition of the elastic dynamics into two subsystems representing the transverse deflections of the beam in two orthogonal planes. These low-order subsystems are used for the derivation of a modal velocity feedback stabilizer using the force and moment actuators at the end body. Simulation results are presented to show the capability of the controller.
Burton, R.; Rock, S.; Springmann, J.; Cutler, J.
An online attitude determination filter is developed for a nano satellite that has no onboard attitude sensors or gyros. Specifically, the attitude of NASA Ames Research Center's O/OREOS, a passively magnetically stabilized 3U CubeSat, is determined using only an estimate of the solar vector obtained from solar panel currents. The filter is based upon the existing multiplicative extended Kalman filter (MEKF) but instead of relying on gyros to drive the motion model, the filter instead incorporates a model of the spacecraft's attitude dynamics in the motion model. An attitude determination accuracy of five degrees is demonstrated, a performance verified using flight data from the University of Michigan's RAX-1. Although the filter was designed for the specific problem of a satellite without gyros or attitude determination it could also be used to provide smoothing of noisy gyro signals or to provide a backup in the event of gyro failures.
Oluwafemi Emmanuel Oni
Full Text Available Power System stability is an essential study in the planning and operation of an efficient, economic, reliable and secure electric power system because it encompasses all the facet of power systems operations, from planning, to conceptual design stages of the project as well as during the systems operating life span. This paper presents different scenario of power system stability studies on a modified IEEE 30-bus system which is subjected to different faults conditions. A scenario whereby the longest high voltage alternating current (HVAC line is replaced with a high voltage direct current (HVDC line was implemented. The results obtained show that the HVDC line enhances system stability more compared to the contemporary HVAC line. Dynamic analysis using RMS simulation tool was used on DigSILENT PowerFactory.
Schiffer, Johannes; Efimov, Denis; Ortega, Romeo; Barabanov, Nikita
Conditions for almost global stability of an operating point of a realistic model of a synchronous generator with constant field current connected to an infinite bus are derived. The analysis is conducted by employing the recently proposed concept of input-to-state stability (ISS)-Leonov functions, which is an extension of the powerful cell structure principle developed by Leonov and Noldus to the ISS framework. Compared with the original ideas of Leonov and Noldus, the ISS-Leonov approach has the advantage of providing additional robustness guarantees. The efficiency of the derived sufficient conditions is illustrated via numerical experiments.This article is part of the themed issue 'Energy management: flexibility, risk and optimization'. © 2017 The Author(s).
Riverso, Stefano; Tucci, Michele; Vasquez, Juan C.
. In this work, we focus on islanded microgrids with bus-connected topology and enhance the primary plug-and-play layer with local virtual impedance loops and secondary coordinated controllers ensuring bus voltage tracking and reactive power sharing. In particular, the secondary control architecture...... is distributed, hence mirroring the modularity of the primary control layer. We validate primary and secondary controllers by performing experiments with both linear and nonlinear loads, on a setup composed of three bus-connected distributed generation units. Most importantly, the stability of the microgrid...... after the addition/removal of distributed generation units is assessed. Overall, the experimental results show the feasibility of the proposed modular control design framework, where generation units can be added/removed on the fly, thus enabling the deployment of virtual power plants that can...
Jang, Jiann-Woei; Plummer, Michael; Bedrossian, Nazareth; Hall, Charles; Jackson, Mark; Spanos, Pol
Many aerospace attitude control systems utilize phase plane control schemes that include nonlinear elements such as dead zone and ideal relay. To evaluate phase plane control robustness, stability margin prediction methods must be developed. Absolute stability is extended to predict stability margins and to define an abort condition. A constrained optimization approach is also used to design flex filters for roll control. The design goal is to optimize vehicle tracking performance while maintaining adequate stability margins. Absolute stability is shown to provide satisfactory stability constraints for the optimization.
Mass-spring and liquid dampers enable structural vibration control to attenuate single, coupled lateral and torsional vibrations in diverse structures. Out of these, the passively tuned liquid damper (TLD) class is wanted due to its broad applicability, extreme reliability, robustness, long life time and ease of manufacturability. In this PhD thesis, the theory, design, verification and validation of multi-mode TLDs in terrestrial and mainly spacecraft (S/C) applications have been studied. Th...
This thesis is organized in two parts. In Part 1, control systems described by a class of nonlinear differential and algebraic equations are introduced. A procedure for local stabilization based on a local state realization is developed. An alternative approach to local stabilization is developed based on a classical linearization of the nonlinear differential-algebraic equations. A theoretical framework is established for solving a tracking problem associated with the differential-algebraic system. First, a simple procedure is developed for the design of a feedback control law which ensures, at least locally, that the tracking error in the closed loop system lies within any given bound if the reference inputs are sufficiently slowly varying. Next, by imposing additional assumptions, a procedure is developed for the design of a feedback control law which ensures that the tracking error in the closed loop system approaches zero exponentially for reference inputs which are not necessarily slowly varying. The control design methodologies are used for simultaneous force and position control in constrained robot systems. The differential-algebraic equations are shown to characterize the slow dynamics of a certain nonlinear control system in nonstandard singularly perturbed form. In Part 2, the attitude stabilization (reorientation) of a rigid spacecraft using only two control torques is considered. First, the case of momentum wheel actuators is considered. The complete spacecraft dynamics are not controllable. However, the spacecraft dynamics are small time locally controllable in a reduced sense. The reduced spacecraft dynamics cannot be asymptotically stabilized using continuous feedback, but a discontinuous feedback control strategy is constructed. Next, the case of gas jet actuators is considered. If the uncontrolled principal axis is not an axis of symmetry, the complete spacecraft dynamics are small time locally controllable. However, the spacecraft attitude
The objective of this paper is to develop a control scheme for stabilization of a hamiltonian system. The method generalizes the results available in the literature on motion control in the Euclidean space to an arbitrary differrential manifol equipped with a metric. This modification is essencial...... for global stabilization of a rotary motion. Along with a model of the system formulated in the Hamilton's canonical from the algorithm uses information about a required potential energy and a dissipation term. The control action is the sum of the gradient of the potential energy and the dissipation force....... It is shown that this control law makes the system uniformly asymptotically stable to the desired reference point. The concepet is very straightforward in the Euclidean space however a global rotation control cannot be tackled.An additional modification is made to address a system which flow lies...
The objective of this paper is to develop a control scheme for stabilization of a hamiltonian system. The method generalizes the results available in the literature on motion control in the Euclidean space to an arbitrary differrential manifol equipped with a metric. This modification is essencial...... for global stabilization of a rotary motion. Along with a model of the system formulated in the Hamilton's canonical from the algorithm uses information about a required potential energy and a dissipation term. The control action is the sum of the gradient of the potential energy and the dissipation force....... It is shown that this control law makes the system uniformly asymptotically stable to the desired reference point. The concepet is very straightforward in the Euclidean space however a global rotation control cannot be tackled.An additional modification is made to address a system which flow lies...
Joshi, Suresh; Kelkar, Atul G.
This paper addresses stabilization and control issues in autonomous capture and manipulation of non-cooperative space objects such as asteroids, space debris, and orbital spacecraft in need of servicing. Such objects are characterized by unknown mass-inertia properties, unknown rotational motion, and irregular shapes, which makes it a challenging control problem. The problem is further compounded by the presence of inherent nonlinearities, signi cant elastic modes with low damping, and parameter uncertainties in the spacecraft. Robust dissipativity-based control laws are presented and are shown to provide global asymptotic stability in spite of model uncertainties and nonlinearities. It is shown that robust stabilization can be accomplished via model-independent dissipativity-based controllers using thrusters alone, while stabilization with attitude and position control can be accomplished using thrusters and torque actuators.
Wu, Wan-fan; Liu, Na; Cheng, Wen-long; Liu, Yi
Highlights: ► A shape-stabilized PCM is used to protect the spacecraft attacked by high energy. ► Taking a satellite as example, it proves the solution given in the work is feasible. ► Low thermal conductivity makes the material above its thermal stability limit. ► It provides guidance on how to choose the shape-stabilized PCM for similar problems. - Abstract: In space, the emergencies such as short-term high heat flux is prone to cause spacecraft thermal control system faults, resulting in temperature anomalies of electronic equipment of the spacecraft and even failures in them. In order to protect the spacecraft attacked by the high energy, a new guard method is proposed. A shape-stabilized phase change material (PCM), which has high thermal conductivity and does not require being tightly packaged, is proposed to be used on the spacecraft. To prove the feasibility of using the material on spacecraft attacked by high energy, the thermal responses for spacecraft with shape-stabilized PCM are investigated in situations of normal and short-term high heat flux, in contrast to that with conventional thermal control system. The results indicate that the shape-stabilized PCM can effectively absorb the heat to prevent the thermal control system faults when the spacecraft’s outer heat flux changes dramatically and has no negative effect on spacecraft in normal heat flux. Additionally the effect of thermal conductivity of PCM on its application effectiveness is discussed
Kim, Seong Joong
Large signal analysis of various spacecraft power systems is performed to predict the bus dynamics in various modes of operation. The large-signal trajectories of the system's operating point are analyzed employing qualitative graphical representation. The analyses are verified through simulation using EASY5 software. Small-signal dynamic characteristics of spacecraft battery charge converter systems are analyzed to facilitate the design of a control loop for optimum performance and stability. Control-loop designs for the charge converters in bus voltage regulation mode, charge current regulation mode, and peak power tracking mode are discussed.
Adam, Niklas; Mitchell, Julie L.; Pickering, Karen D.
Wastewater stabilization is an essential component of the spacecraft water cycle. The purpose of stabilizing wastewater is two-fold. First, stabilization prevents the breakdown of urea into ammonia, a toxic gas at high concentrations. Second, it prevents the growth of microorganisms, thereby mitigating hardware and water quality issues due to due biofilm and planktonic growth. Current stabilization techniques involve oxidizers and strong acids (pH=2) such as chromic and sulfuric acid, which are highly toxic and pose a risk to crew health. The purpose of this effort is to explore less toxic stabilization techniques, such as food-grade and commercial care preservatives. Additionally, certain preservatives were tested in the presence of a low-toxicity organic acid. Triplicate 300-mL volumes of urine were dosed with a predetermined quantity of stabilizer and stored for two weeks. During that time, pH, total organic carbon (TOC), ammonia, and turbidity were monitored. Those preservatives that showed the lowest visible microbial growth and stable pH were further tested in a six-month stability study. The results of the six-month study are also included in this paper.
Adam, Niklas; Mitchell, Julie; Pickering, Karen; Carrier, Chris; Vega, Letty; Muirhead, Dean
Wastewater stabilization was an essential component of the spacecraft water cycle. The purpose of stabilizing wastewater was two-fold. First, stabilization prevents the breakdown of urea into ammonia, a toxic gas at high concentrations. Second, it prevents the growth of microorganisms, thereby mitigating hardware and water quality issues due to due biofilm and planktonic growth. Current stabilization techniques involve oxidizers and strong acids (pH=2) such as chromic and sulfuric acid, which are highly toxic and pose a risk to crew health. The purpose of this effort was to explore less toxic stabilization techniques, such as food-grade and commercial care preservatives. Additionally, certain preservatives were tested in the presence of a low-toxicity organic acid. Triplicate 300-mL volumes of urine were dosed with a predetermined quantity of stabilizer and stored for two weeks. During that time, pH, total organic carbon (TOC), ammonia, and turbidity were monitored. Those preservatives that showed the lowest visible microbial growth and stable pH were further tested in a six-month stability study. The results of the six-month study are also included in this paper.
Mitchell, Julie L.; Adam, Niklas; Pickering, Karen D.; Alvarez, Giraldo N.
Wastewater stabilization was an essential component of the spacecraft water cycle. The purpose of stabilizing wastewater was two-fold. First, stabilization prevents the breakdown of urea into ammonia, a toxic gas at high concentrations. Second, it prevents the growth of microorganisms, thereby mitigating hardware and water quality issues due to due biofilm and planktonic growth. Current stabilization techniques involve oxidizers and strong acids (pH=2) such as chromic and sulfuric acid, which are highly toxic and pose a risk to crew health. The purpose of this effort was to explore less toxic stabilization techniques, such as food-grade and commercial care preservatives. Additionally, certain preservatives were tested in the presence of a low-toxicity organic acid. Triplicate 300-milliliter volumes of urine were dosed with a predetermined quantity of stabilizer and stored for two weeks. During that time, pH, total organic carbon (TOC), ammonia, and turbidity were monitored. Those preservatives that showed the lowest visible microbial growth and stable pH were further tested in a six-month stability study. The results of the six-month study are also included in this paper.
Yan, Ruidong; Wu, Zhong
To achieve the high-precision attitude stabilization for the flexible spacecraft in the presence of space environmental disturbances, unmodeled dynamics, and the disturbances caused by the elastic vibration of flexible appendages, an extended disturbance observer (EDO) based controller is proposed. The proposed controller is formulated by combining EDO and a backstepping feedback controller. EDO is used to estimate the disturbance, which is modeled as an unknown high-order differentiable equation and the rth-order derivative of the disturbance is assumed to be bounded. Compared to the conventional first-order disturbance observer, the higher order EDO offers improvement in estimate accuracy, if the absolute values of poles for EDO transfer function are chosen larger than the frequency content of the disturbance. Then, the output of EDO plus the backstepping feedback controller are applied to stabilize the attitude with high precision by rejecting disturbances for the flexible spacecraft. Finally, numerical simulations have been conducted to verify the effectiveness of the proposed controller.
National Aeronautics and Space Administration — The Software Bus Network (SBN) is a software application that enables seamless flight software communication between multiple processors or spacecraft. The SBN is...
Pham, Timothy T.; Machuzak, Richard J.; Bedrossian, Alina; Kelly, Richard M.; Liao, Jason C.
This software provides an automated capability to measure and qualify the frequency stability performance of the Deep Space Network (DSN) ground system, using daily spacecraft tracking data. The results help to verify if the DSN performance is meeting its specification, therefore ensuring commitments to flight missions; in particular, the radio science investigations. The rich set of data also helps the DSN Operations and Maintenance team to identify the trends and patterns, allowing them to identify the antennas of lower performance and implement corrective action in a timely manner. Unlike the traditional approach where the performance can only be obtained from special calibration sessions that are both time-consuming and require manual setup, the new method taps into the daily spacecraft tracking data. This new approach significantly increases the amount of data available for analysis, roughly by two orders of magnitude, making it possible to conduct trend analysis with good confidence. The software is built with automation in mind for end-to-end processing. From the inputs gathering to computation analysis and later data visualization of the results, all steps are done automatically, making the data production at near zero cost. This allows the limited engineering resource to focus on high-level assessment and to follow up with the exceptions/deviations. To make it possible to process the continual stream of daily incoming data without much effort, and to understand the results quickly, the processing needs to be automated and the data summarized at a high level. Special attention needs to be given to data gathering, input validation, handling anomalous conditions, computation, and presenting the results in a visual form that makes it easy to spot items of exception/deviation so that further analysis can be directed and corrective actions followed.
National Aeronautics and Space Administration — Development of novel spacecraft guidance control architectures and algorithms that work in conjunction with robot manipulator control for application to ARM mission...
Kwon, Uk Hyeon; Kim, Hyeong Seok; Kim, Dong Seong
This book is about field bus communications network, introducing data communications network, field bus for industry and standardization of communication protocol, basic of data communication about structure, local area network, introduction of field bus for industry like utility of field bus, profibus, foundation field bus, worldFIP, device net, inter bus, control net, P-net and SERCOS, evaluation of field bus performance including computer simulation tool, and network modeling, and field bus practice.
The aims of this course are: 1. To introduce the general concepts of buses used to interconnect processors, perpherals, and instrumentation. 2. To classify, albeit crudely, different types of bus systems. 3. To give some examples of past, present, and future buses as applied to the field of high-energy physics, including some details of software. 4. To provide references for further study. (orig.)
...-banding compliant); replacement or the modernization of bus maintenance and revenue service (passenger... DEPARTMENT OF TRANSPORTATION Federal Transit Administration Discretionary Bus and Bus Facilities... Good Repair Bus and Bus Facilities Initiative Funds: Solicitation of Project Proposals. SUMMARY: The...
...-banding compliant); replacement or the modernization of bus maintenance and revenue service (passenger... DEPARTMENT OF TRANSPORTATION Federal Transit Administration Discretionary Bus and Bus Facilities... good repair bus and bus facilities initiative funds: Solicitation of project proposals. SUMMARY: The...
Sable, Dan M.; Cho, Bo H.; Lee, Fred C.
This paper addresses the problem of system stability of the NASA EOS satellite power system. A potential stability problem exists without a clear specification of the payload input impedance characteristic. Design guidelines are established for the control of the power system and the individual subcomponents to help insure stability with an unknown complex load. A testbed of the EOS power system is employed to verify the analysis.
Kim, Seong J.; Cho, Bo H.
In spacecraft battery charger systems, switching regulators are widely used for bus voltage regulation, charge current regulation, and peak power tracking. Small-signal dynamic characteristics of the battery charging subsystem of direct energy transfer (DET) and peak power tracking (PPT) systems are analyzed to facilitate design of the control loop for optimum performance and stability. Control loop designs of the charger in various modes of operation are discussed. Analyses are verified through simulations. It is shown that when the charger operates in the bus voltage regulation mode, the control-to-voltage transfer function has a negative DC gain and two LHP zeros in both the DET and PPT systems. The control-to-inductor current transfer function also has a negative DC gain and a RHP zero. Thus, in the current-mode control, the current loop can no longer be used to stabilize the system. When the system operates in the charge current regulation mode, the charger operates with a fixed duty cycle which is determined by the regulated bus voltage and the battery voltage. Without an input filter, the converter becomes a first-order system. When the peak power tracker is inactive, the operating point of the solar array output moves to the voltage source region. Thus, the solar array behaves as a stiff voltage source to a constant power load.
William Reis Silva
Full Text Available This work aims to analyze the stability of the rotational motion of artificial satellites in circular orbit with the influence of gravity gradient torque, using the Andoyer variables. The used method in this paper to analyze stability is the Kovalev-Savchenko theorem. This method requires the reduction of the Hamiltonian in its normal form up to fourth order by means of canonical transformations around equilibrium points. The coefficients of the normal Hamiltonian are indispensable in the study of nonlinear stability of its equilibrium points according to the three established conditions in the theorem. Some physical and orbital data of real satellites were used in the numerical simulations. In comparison with previous work, the results show a greater number of equilibrium points and an optimization in the algorithm to determine the normal form and stability analysis. The results of this paper can directly contribute in maintaining the attitude of artificial satellites.
Full Text Available This paper addresses the observer-based control problem of spacecraft rendezvous with nonuniform sampling period. The relative dynamic model is based on the classical Clohessy-Wiltshire equation, and sensor nonlinearity and sampling are considered together in a unified framework. The purpose of this paper is to perform an observer-based controller synthesis by using sampled and saturated output measurements, such that the resulting closed-loop system is exponentially stable. A time-dependent Lyapunov functional is developed which depends on time and the upper bound of the sampling period and also does not grow along the input update times. The controller design problem is solved in terms of the linear matrix inequality method, and the obtained results are less conservative than using the traditional Lyapunov functionals. Finally, a numerical simulation example is built to show the validity of the developed sampled-data control strategy.
Janschek, K.; Tchernykh, V.; Dyblenko, S.; Harnisch, B.
Pushbroom scan cameras with linear image sensors, commonly used for Earth observation from satellites, require high attitude stability during the image acquisition. Especially noticeable are the effects of high frequency attitude variations originating from micro shocks and vibrations, produced by momentum and reaction wheels, mechanically activated coolers, steering and deployment mechanics and other reasons. The SMARTSCAN imaging concept offers high quality imaging even with moderate satellite attitude stability on a sole opto-electronic basis without any moving parts. It uses real-time recording of the actual image motion in the focal plane of the remote sensing camera during the frame acquisition and a posteriori correction of the obtained image distortions on base of the image motion record. Exceptional real-time performances with subpixel accuracy image motion measurement are provided by an innovative high-speed onboard optoelectronic correlation processor. SMARTSCAN allows therefore using smart pushbroom cameras for hyper-spectral imagers on satellites and platforms which are not specially intended for imaging missions, e.g. micro satellites. The paper gives an overview on the system concept and main technologies used (advanced optical correlator for ultra high-speed image motion tracking), it discusses the conceptual design for a smart compact space camera and it reports on airborne test results of a functional breadboard model.
Hoover, S. A.; Daughtridge, S.; Johnson, P. J.; King, S. T.
The Orion 1 spacecraft is a three-axis stabilized geostationary earth orbiting commercial communications satellite which was launched on November 29, 1994 aboard an Atlas II launch vehicle. The power subsystem is a dual bus, dual battery semi-regulated system with one 78 Ampere-hour nickel-hydrogen battery per bus. The batteries were built and tested by Eagle Picher Industries, Inc., of Joplin, MO and were integrated into the spacecraft by its manufacturer, Matra Marconi Space UK Ltd. This paper presents the results obtained during the first four in-orbit reconditioning cycles and compares the battery performance to ground test data. In addition, the on-station battery management strategy and implementation constraints are described. Battery performance has been nominal throughout each reconditioning cycle and subsequent eclipse season.
Small Satellite Technology Initiative (SSTI) Lewis Spacecraft Program is evaluated. Spacecraft integration, test, launch, and spacecraft bus are discussed. Payloads and technology demonstrations are presented. Mission data management system and ground segment are also addressed.
Razi Iqbal; Muhammad Usman Ghani
The purpose of this paper is to discuss Intelligent Bus Stops in a special Demand Responsive Transit (DRT), the Flexible Bus System. These Intelligent Bus Stops are more efficient and information rich than Traditional Bus Stops. The real time synchronization of the Flexible Bus System makes it unique as compared to Traditional Bus Systems. The Main concern is to make Bus Stops intelligent and information rich. Buses are informed about the no. of passengers waiting at the upcoming ...
A bus station contains several bus stops. Only one bus can occupy a singlebus stop at a time. Buses of many trips arrive to the bus station during the day (or duringanother considered period) and every bus occupies a bus stop for a certain time interval.The set of available bus stops is limited. This paper studies a problem how to assign a busstop to every bus trip in order to minimize the number of assigned bus stops and in orderto comply several additional conditions. Several approaches to ...
The peripheral component interconnect (PCI) bus is the dominant bus system used to connect the different elements making up today''s high-performance computer systems. Different PCI implementations have also been developed for such applications as telecommunications and embedded computing. If an application calls for high speed, high reliability, flexible configuration, and bus mastering, then PCI is the only logical bus choice. This book is an applications-oriented introduction to the PCI bus, with an emphasis on implementing PCI in a variety of computer architectures. Special attention is given to industrial and mission-critical applications of PCI bus.·Fully describes PCI electrical specifications, mechanical requirements, and signal types·Covers advanced topics through numerous design examples to increase the readers understanding of the subject ·Includes updated coverage of PCI-X 2.0
National Aeronautics and Space Administration — To reduce the accumulation of human-made "space junk", NASA has implemented a rule requiring the disposal of spacecraft below 2,000 km within 25 years. By deploying...
This paper considers the problem of estimating bus passenger waiting times at bus stops using incomplete bus arrivals data. This is of importance to bus operators and regulators as passenger waiting time is a key performance measure. Average waiting times are usually estimated from bus headways, that is, time gaps between buses. It is both time-consuming and expensive to measure bus arrival times manually so methods using automatic vehicle location systems are attractive; however, these syste...
Full Text Available The purpose of this paper is to discuss Intelligent Bus Stops in a special Demand Responsive Transit (DRT, the Flexible Bus System. These Intelligent Bus Stops are more efficient and information rich than Traditional Bus Stops. The real time synchronization of the Flexible Bus System makes it unique as compared to Traditional Bus Systems. The Main concern is to make Bus Stops intelligent and information rich. Buses are informed about the no. of passengers waiting at the upcoming Bus Stops. If there are no passengers to ride or get off on upcoming Bus Stop, the Bus can skip that Bus Stop and head towards the next Bus Stop where passenger is waiting, which will decrease the ride time of the passengers on the Bus and also the wait time of the passengers waiting on the upcoming Bus Stops. Providing more information at Bus Stops about the Destination (Time to Destination, Distance to Destination etc. and Buses (Bus Location, Arrival Time of Bus etc. makes it easier for the passengers to decide whether to ride a particular Bus or not.
Pure electric buses (EBs) offer an alternative fuel for the nations transit bus systems. To : evaluate EBs in a transit setting, this project investigated the five electric bus fleet of the : StarMetro transit system of the city of Tallahassee, FL...
The CERN Staff Association will stop selling TPG bus passes. All active and retired members of the CERN personnel will be able to purchase Unireso bus passes from the CERN Hostel - Building 39 (Meyrin site) from 1st February 2013. For more information: https://cds.cern.ch/journal/CERNBulletin/2013/04/Announcements/1505279?ln=en
National Highway Traffic Safety Administration (DOT), Washington, DC.
This publication provides a summary and update of school bus-safety activities conducted by the National Highway Traffic Safety Administration (NHTSA). This report discusses Congressional mandates and NHTSA's actions to improve school-bus safety (which include programs that affect human behavior and motor-vehicle safety performance), the magnitude…
Rutka, M. J.
In this thesis an integrated sensor bus interface is presented. The proposed bus offers a number of interface procedures to enhance the system flexibility. It enables a 13-bit data exchange per message frame, automatic addressing, device clearing and resetting, and handling of service-request and polling procedures. Chapter 1 provides an overview of the existing data transmission technologies. It presents the most popular digital buses along with their application fields. Also other research activities on sensor buses are described. Chapter 2 deals with the requirements which have to be imposed on the desired sensor bus. It shows both communication and compatibility requirements. Chapter 3 introduces the proposed sensor bus. It presents the interface structure together with implemented bus procedures. The detailed description of the proposed sensor bus protocol is given in Chapter 4. It is divided into two parts; a logical layer description (i.e., sensor bus protocol) and a physical layer description (i.e., transmission medium and electrical characteristics). Chapter 5 deals with the compatibility issue. It investigates differences between typical processes used for sensors and digital circuits. Chapter 6 shows the design of a sensor bus interface prototype. In Chapter 7 the performance of the fabricated interface is discussed.
Durieu, L.; Vignes, M.; Wolstenholme, P.
A study has been made of some factors determining the performance and cost-effectiveness of microcomputer bus systems implemented in Europa crates. An experimental system has been specified and a number of modules constructed in accordance with the specification, in order to test the validity of some of the ideas proposed. It has been demonstrated that the bus interfacing logic can be simple and inexpensive, while maintaining a high degree of processor independence and also a high degree of transparency in operation. The number of pins required by the bus is minimized by multiplexing address and data. A series termination for the drive of the multiplexed lines permits cross-talk to be reduced to insignificant levels: this technique is recommended for wider application. The experimental bus is proposed as a basis for the construction of simple microcomputer-based instrumentation systems. (orig.)
Rittner-Heir, Robbin M.
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)
On 15 December, an airport bus will be transformed in the image of CERN. The bus will be seen by the thousands of travellers arriving in Geneva, informing them of the possibility to visit CERN. Sketch of the bus. The good relationship between Geneva International Airport and CERN started several years ago. In 2004 the airport put advertising space in the arrivals area at CERN's disposal free of charge. Now, starting on 15 December, a 40-foot long bus will display a giant sticker advertisement depicting CERN as it takes passengers over the airport tarmac to their planes. This is no ordinary sticker, and it was no mean task to attach it to the bus. The task of producing and attaching it was entrusted to Geneva-based specialists Mathys SA. With the ski season opening on 15 December, there will be many travellers arriving at the airport, and the bus will be ready to receive them. When one thinks of CERN, the subjects that naturally come to mind are the LHC, the mysteries of the Universe...
Hall, William A.
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.
This is a practical tutorial containing hands-on examples for creating a messaging and SOA based service bus.This book is for .NET developers who are looking for ways to overcome problems related to buggy third party web service integrations, codebases that have grown into a big ball of mud, and batch jobs failure.
Full Text Available The coordination between bus rapid transit (BRT and feeder bus service is helpful in improving the operational efficiency and service level of urban public transport system. Therefore, a coordinated operation model of BRT and bus is intended to develop in this paper. The total costs are formulated and optimized by genetic algorithm. Moreover, the skip-stop BRT operation is considered when building the coordinated operation model. A case of the existing bus network in Beijing is studied, the proposed coordinated operation model of BRT and bus is applied, and the optimized headway and costs are obtained. The results show that the coordinated operation model could effectively decrease the total costs of the transit system and the transfer time of passengers. The results also suggest that the coordination between the skip-stop BRT and bus during peak hour is more effective than non-coordination operation.
Frith, James; Anz-Meador, Phillip; Cowardin, Heather; Buckalew, Brent; Lederer, Susan
The Boeing HS-376 spin stabilized spacecraft was a popular design that was launched continuously into geosynchronous orbit starting in 1980, with the last launch occurring in 2003. Over 50 of the HS-376 buses were produced to fulfill a variety of different communication missions for countries all over the world. The design of the bus is easily approximated as a telescoping cylinder that is covered with solar cells and an Earth-facing antenna that is despun at the top of the cylinder. The similarity in design and the number of spacecraft launched over a long period of time make the HS-376 a prime target for studying the effects of solar weathering on solar panels as a function of time. A selection of primarily non-operational HS-376 spacecraft launched over a 20-year time period were observed using the United Kingdom Infrared Telescope on Mauna Kea and multi-band, near-infrared photometry produced. Each spacecraft was observed for an entire night cycling through ZYJHK filters and time-varying colors produced to compare near-infrared color as a function of launch date. The resulting analysis shown here may help in the future to set launch date constraints on the parent object of unidentified debris objects or other unknown spacecraft.
Two close-open operations are required each pulse cycle at approximately 3 MA with the breaker in series with the burn supply, both forming a leg in parallel with the E-coil and the homopolar. To conduct the 3-MA current, approximately 30 breaker units are connected in parallel. Each unit is equipped with a counterpulse capacitor bank, and the bus for the 30 units is provided with a common saturable reactor core made of strip steel wound around the bus. Oil breakers of a special design are chosen because of their high arc resistance facilitating the current transfer to the homopolar machine and for obtaining precision timing in opening and closing of the contacts. The precision timing is achieved by a shock wave method with the oil serving as hydraulic medium. Each of the parallel breaker units possesses two sets of contacts, a stationary and a transient one. A 1-mΩ resistor in series with the transient contacts of each breaker unit is to improve the current sharing. The bus consists of room temperature copper, stranded and transposed to help provide current equalization under transient conditions
A time-headway model is presented to mimic bus behavior on the bus route. The motion of a bus is described in terms of the time headway between its bus and the bus in front. We study the bunching behavior of buses induced by interacting with other buses and passengers. It is shown that the dynamical phase transitions among the inhomogeneous bunching phase, the homogeneous free phase, the coexisting phase, and the homogeneous congested phase occur with varying the initial time headway. We study the effect of not stopping at bus stops on the time-headway profile. It is found that the bunching transition lines are consistent with the neutral stability curves obtained by the linear stability analysis.
National Aeronautics and Space Administration — Develop a Universal Digital Processor Bus architecture using state of the art commercial packaging technologies. This work will transition commercial advanced- yet...
Kalfayan, S. H.
Spacecraft sterilization is a vital factor in projects for the successful biological exploration of other planets. The microorganisms of major concern are the fungi and bacteria. Sterilization procedures are oriented toward the destruction of bacterial spores. Gaseous sterilants are examined, giving attention to formaldehyde, beta-propiolactone, ethylene oxide, and the chemistry of the bactericidal action of sterilants. Radiation has been seriously considered as another method for spacecraft sterilization. Dry heat sterilization is discussed together with the effects of ethylene oxide decontamination and dry heat sterilization on materials.
If you are an Enterprise C# developer who wishes to extend your knowledge of NServiceBus and Enterprise Service Bus in C#, this is the book for you. This book is designed to enhance the education of ESBs and their messaging, whether you are a beginner or a seasoned expert in Enterprise C#, Apex, and Visualforce pages.
Greenwell, T. J.
The Multimission Modular Spacecraft (MMS) provides a standard spacecraft bus to a user for a variety of space missions ranging from near-earth to synchronous orbits. The present paper describes the philosophy behind the MMS module test program and discusses the implementation of the test program. It is concluded that the MMS module test program provides an effective and comprehensive customer buy-off at the subsystem contractor's plant, is an optimum approach for checkout of the subsystems prior to use for on-orbit servicing in the Shuttle Cargo Bay, and is a cost-effective technique for environmental testing.
Viterna, Larry A.
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.
Full Text Available The DC bus voltage stability control is one key technology to ensure that Active Power Filter (APF operates stably. The external disturbances such as power grid and load fluctuation and the system parameters changing may affect the stability of APF DC bus voltage and the normal operation of APF. The mathematical model of DC bus voltage is established according to power balance principle and a DC bus voltage piecewise reaching law variable structure control algorithm is proposed to solve the above problem, and the design method is given. The simulation and experiment results proved that the proposed variable structure control algorithm can eliminate the chattering problem existing in traditional variable structure control effectively, is insensitive to system disturbance, and has good robustness and fast dynamic response speed and stable DC bus voltage with small fluctuation. The above advantages ensure the compensation effect of APF.
Sellmaier, Florian; Schmidhuber, Michael
The book describes the basic concepts of spaceflight operations, for both, human and unmanned missions. The basic subsystems of a space vehicle are explained in dedicated chapters, the relationship of spacecraft design and the very unique space environment are laid out. Flight dynamics are taught as well as ground segment requirements. Mission operations are divided into preparation including management aspects, execution and planning. Deep space missions and space robotic operations are included as special cases. The book is based on a course held at the German Space Operation Center (GSOC).
Frith, J.; Anz-Meador, P.; Lederer, S.; Cowardin, H.; Buckalew, B.
The Boeing HS-376 spin stabilized spacecraft was a popular design that was launched continuously into geosynchronous orbit starting in 1980 with the last launch occurring in 2002. Over 50 of the HS-376 buses were produced to fulfill a variety of different communication missions for countries all over the world. The design of the bus is easily approximated as a telescoping cylinder that is covered with solar cells and an Earth facing antenna that is despun at the top of the cylinder. The similarity in design and the number of spacecraft launched over a long period of time make the HS-376 a prime target for studying the effects of solar weathering on solar panels as a function of time. A selection of primarily non-operational HS-376 spacecraft launched over a 20 year time period were observed using the United Kingdom Infrared Telescope on Mauna Kea and multi-band near-infrared photometry produced. Each spacecraft was observed for an entire night cycling through ZYJHK filters and time-varying colors produced to compare near-infrared color as a function of launch date. The resulting analysis shown here may help in the future to set launch date constraints on the parent object of unidentified debris objects or other unknown spacecraft.
Frith, James; Anz-Meador, Philip; Lederer, Sue; Cowardin, Heather; Buckalew, Brent
The Boeing HS-376 spin stabilized spacecraft was a popular design that was launched continuously into geosynchronous orbit starting in 1980 with the last launch occurring in 2002. Over 50 of the HS-376 buses were produced to fulfill a variety of different communication missions for countries all over the world. The design of the bus is easily approximated as a telescoping cylinder that is covered with solar cells and an Earth facing antenna that is despun at the top of the cylinder. The similarity in design and the number of spacecraft launched over a long period of time make the HS-376 a prime target for studying the effects of solar weathering on solar panels as a function of time. A selection of primarily non-operational HS-376 spacecraft launched over a 20 year time period were observed using the United Kingdom Infrared Telescope on Mauna Kea and multi-band near-infrared photometry produced. Each spacecraft was observed for an entire night cycling through ZYJHK filters and time-varying colors produced to compare near-infrared color as a function of launch date. The resulting analysis shown here may help in the future to set launch date constraints on the parent object of unidentified debris objects or other unknown spacecraft.
This 4-page Clean Cities fact sheet provides a list of the currently available (and soon to be available) model year 2004 alternative fuel school bus and school bus engine products. It includes information from Blue Bird Corporation, Collins Bus Corporation, Corbeil Bus, Ford Motor Company, General Motors Corporation, Thomas Built Buses, Inc., Clean Air Partners, Cummins Westport, and Deere & Company.
Adheesh, SR; Vasisht, Shravanth M; Ramasesha, Sheela K
The Bangalore Metropolitan Transport Corporation (BMTC) took an initiative to check the overall benefits of introducing electric buses as a suitable replacement for the diesel buses to tackle the burgeoning pollution in the city of Bengaluru, India. For a trial run of three months, an electric bus was procured from a Chinese company `Build Your Dreams' (BYD). Data were collected by BMTC on the operation and maintenance of the bus. This new initiative, if rightly guided, could have a direct im...
Detwiler, R. C.; Smith, R. L.
The Galileo PMAD (power management and distribution system) is described, and the design drivers that established the final as-built hardware are discussed. The spacecraft is powered by two general-purpose heat-source-radioisotope thermoelectric generators. Power bus regulation is provided by a shunt regulator. Galileo PMAD distributes a 570-W beginning of mission (BOM) power source to a user complement of some 137 load elements. Extensive use of pyrotechnics requires two pyro switching subassemblies. They initiate 148 squibs which operate the 47 pyro devices on the spacecraft. Detection and correction of faults in the Galileo PMAD is an autonomous feature dictated by requirements for long life and reliability in the absence of ground-based support. Volatile computer memories in the spacecraft command and data system and attitude control system require a continuous source of backup power during all anticipated power bus fault scenarios. Power for the Jupiter Probe is conditioned, isolated, and controlled by a Probe interface subassembly. Flight performance of the spacecraft and the PMAD has been successful to date, with no major anomalies.
Jackson, George L.; LaBel, Kenneth A.; Marshall, Cheryl; Barth, Janet; Seidleck, Christina; Marshall, Paul
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.
The third Spacecraft Charging Technology Conference proceedings contain 66 papers on the geosynchronous plasma environment, spacecraft modeling, charged particle environment interactions with spacecraft, spacecraft materials characterization, and satellite design and testing. The proceedings is a compilation of the state of the art of spacecraft charging and environmental interaction phenomena.
Pan, Shu-ming; Hargarten, Stephen; Zhu, Shan-kuan
There is no safer way to transport a child than a school bus. Fatal crashes involving occupants are extremely rare events in the US. In recent years, school bus transportation began to develop in China. We want to bring advanced experience on school bus safety in Western countries such as the US to developing countries. We searched the papers related to school bus safety from Medline, Chinese Scientific Journals Database and the Web of the National Highway Traffic Safety Administration (NHTSA). There were only 9 papers related to school bus safety, which showed that higher levels of safety standards on school buses, school bus-related transportation and environmental laws and injury prevention were the primary reasons for the desired outcome. Few school bus is related to deaths and injuries in the developed countries. The developing countries should make strict environmental laws and standards on school bus safety to prevent children's injury and death.
Many transit operators routinely collect ridership data in order to provide a : basis for the planning of bus services. Often a survey is conducted of bus : riders to determine their riding habits, their views about the quality of : current service, ...
... 8, 2009. The Livability Bus program makes funds available to public transit providers to finance... 2-New York, Administrator, Region 7-Kansas One Bowling Green, Room 429, New City, MO, 901 Locust... Metropolitan Office, Region 2-New York, One Bowling Green, Room 428, New York, NY 10004-1415, Tel. 212-668-2202...
Fa, Jinghuai; Zhao, Chunhe; Liu, Jian; Chen, Ray T.
In order to utilize the high speed of optical interconnects and overcome the latencyproblem of a large bus structure, we proposed an architecture of optoelectronic hierarchical bus system. Waveguide hologram implementations, and its associated cache coherence problem are addressed. In our configuration, bus hierarchy is controlled with electronic programmable plates. Optical signals can be transmitted on all-optical paths without intermediate conversions.
Hayhurst, Marc R.; Bitten, Robert E.; Shinn, Stephen A.; Judnick, Daniel C.; Hallgrimson, Ingrid E.; Youngs, Megan A.
Although spacecraft developers have been moving towards standardized product lines as the aerospace industry has matured, NASA's continual need to push the cutting edge of science to accomplish unique, challenging missions can still lead to spacecraft resource growth over time. This paper assesses historical mass, power, cost, and schedule growth for multiple NASA spacecraft from the last twenty years and compares to industry reserve guidelines to understand where the guidelines may fall short. Growth is assessed from project start to launch, from the time of the preliminary design review (PDR) to launch and from the time of the critical design review (CDR) to launch. Data is also assessed not just at the spacecraft bus level, but also at the subsystem level wherever possible, to help obtain further insight into possible drivers of growth. Potential recommendations to minimize spacecraft mass, power, cost, and schedule growth for future missions are also discussed.
Lavrijsen, Wim T.L.P.
A software bus, just like its hardware equivalent, allows for the discovery, installation, configuration, loading, unloading, and run-time replacement of software components, as well as channeling of inter-component communication. Python, a popular open-source programming language, encourages a modular design on software written in it, but it offers little or no component functionality. However, the language and its interpreter provide sufficient hooks to implement a thin, integral layer of component support. This functionality can be presented to the developer in the form of a module, making it very easy to use. This paper describes a Pythonmodule, PyBus, with which the concept of a ''software bus'' can be realized in Python. It demonstrates, within the context of the ATLAS software framework Athena, how PyBus can be used for the installation and (run-time) configuration of software, not necessarily Python modules, from a Python application in a way that is transparent to the end-user
Gu, Wei; Yu, Jie; Ji, Yuxiong; van der Gun, J.P.T.; Pel, A.J.; Zhang, H. Michael; van Arem, B.
Metro disruptions due to unexpected events reduce transit system reliability, resulting in significant productivity loss and long passenger delays. Bus bridging strategy is often used to connect stations affected by metro disruptions such that passengers could continue their journey. The literature
Waller, Lewis G.; Shortridge, Keith; Farrell, Tony J.; Vuong, Minh; Muller, Rolf; Sheinis, Andrew I.
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.
Tao, Ren; Yi-Fan, Wang; Miao-Miao, Liu; Yan-Jie, Xu
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).
Hoff, Brian Douglas [East Peoria, IL; Akasam, Sivaprasad [Peoria, IL
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.
Ubaidillah, Setiawan, Budi Agus; Aridharma, Airlangga Putra; Lenggana, Bhre Wangsa; Caesar, Bernardus Placenta Previo
Articulated buses have been being preferred as public transportation modes due to their operational capacity. Therefore, passenger safety must be the priority of this public service vehicle. This research focused on the analytical approach of steering characteristics of an articulated bus when it maneuvered steadily. Such turning condition could be referred as a stability parameter of the bus for preliminary handling assessment. The analytical approach employed kinematics relationship between front and rear bodies as well as steering capabilities. The quasi steady model was developed to determine steering parameters such as turning radius, oversteer, and understeer. The mathematical model was useful for determining both coefficients of understeer and oversteer. The dimension of articulated bus followed a commonly used bus as utilized in Trans Jakarta busses. Based on the simulation, for one minimum center of the body, the turning radius was calculated about 8.8 m and 7.6 m at steady turning speed of 10 km/h. In neutral condition, the minimum road radius should be 6.5 m at 10 km/h and 6.9 m at 40 km/h. For two centers of the body and oversteer condition, the front body has the turning radius of 8.8 m, while, the rear body has the turning radius of 9.8 m at both turning speeds of 40 km/h. The other steering parameters were discussed accordingly.
Hammerstrom, Donald J.; Adgerson, Jewel D.; Sastry, Chellury; Pratt, Richard M.; Pratt, Robert G.
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.
address the hardware-software interaction between a digital data bus and an avionic system. Very Large Scale Integration (VLSI) ICs and multiversion ...the SCP. In 1984, the Sperry Corporation developed a fault tolerant system which employed multiversion programming, voting, and monitoring for error... MULTIVERSION PROGRAMMING. N-version programming. 226 N-VERSION PROGRAMMING. The independent coding of a number, N, of redundant computer programs that
Geneva's Public Transport services (TPG) have recently inaugurated a new bus line 28, connecting the La Tour Hospital in Meyrin to the international organisations in Geneva, via the airport. All signs associated with this route will be yellow in colour. Timetables and route details can be found at http://www.tpg.ch. Relations with the Host States Service http://www.cern.ch/relations/ Tel. 72848
Aceves-González, Carlos; May, Andrew; Cook, Sharon
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.
This report summarizes the experience and early results from a fuel cell bus demonstration funded by the Federal Transit Administration (FTA) under the National Fuel Cell Bus Program. A team led by the Center for Transportation and the Environment an...
Yasmin, Shamsunnahar; Anowar, Sabreena; Tay, Richard
School bus safety is a community concern because parents expect their children to be transported to and from school safely. However, relatively few studies have been devoted to examining the factors contributing to school bus crashes. In this study, a logistic regression model is used to delineate the factors that contribute to school bus collisions from collisions involving other types of buses. As expected, we find significant differences in crash factors arising from differences in exposur...
Noorfakhriah Yaakub; Madzlan Napiah
Public bus service plays a significant role in our society as people movers and to facilitate travels within towns and districts. The quality of service of public bus is always being regarded as poor, or rather, underestimated as second class means of transportation. Reliability of service, or the ability to deliver service as planned, is one key element in perceiving the quality of bus service and the punctuality index is one of the performance parameters in determining the service rel...
Liu, Yi; Jia, Yuanhua; Feng, Xuesong; Wu, Jiang
A Bayesian network is used to estimate revenues of bus services in consideration of the effect of bus travel demands, passenger transport distances, and so on. In this research, the area X in Beijing has been selected as the study area because of its relatively high bus travel demand and, on the contrary, unsatisfactory bus services. It is suggested that the proposed Bayesian network approach is able to rationally predict the probabilities of different revenues of various route services, from...
The interaction of the aerospace environment with spacecraft surfaces and onboard, high voltage spacecraft systems operating over a wide range of altitudes from low Earth orbit to geosynchronous orbit is considered. Emphasis is placed on control of spacecraft electric potential. Electron and ion beams, plasma neutralizers material selection, and magnetic shielding are among the topics discussed.
Wei, Zhanji; Li, Dongxu; Luo, Qing; Jiang, Jianping
The microvibrations generated by flywheels running at full speed onboard high precision spacecrafts will affect stability of the spacecraft bus and further degrade pointing accuracy of the payload. A passive vibration isolation platform comprised of multi-segment zig-zag beams is proposed to isolate disturbances of the flywheel. By considering the flywheel and the platform as an integral system with gyroscopic effects, an equivalent dynamic model is developed and verified through eigenvalue and frequency response analysis. The critical speeds of the system are deduced and expressed as functions of system parameters. The vibration isolation performance of the platform under synchronal and high-order harmonic disturbances caused by the flywheel is investigated. It is found that the speed range within which the passive platform is effective and the disturbance decay rate of the system are greatly influenced by the locations of the critical speeds. Structure optimization of the platform is carried out to enhance its performance. Simulation results show that a properly designed vibration isolation platform can effectively reduce disturbances emitted by the flywheel operating above the critical speeds of the system.
This report summarizes the experience and early results from the American Fuel Cell Bus Project, a fuel cell electric bus demonstration : funded by the Federal Transit Administration (FTA) under the National Fuel Cell Bus Program. A team led by CALST...
Cafiso, Salvatore; Di Graziano, Alessandro; Pappalardo, Giuseppina
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
Dorn, Lisa; Stannard, Jenny
In order to combat the problem of novice bus driver risk, a bus simulator was developed to improve decision-making at hazards that are most often associated with bus crashes. If the simulator is capable of discriminating between novice and experienced bus drivers then it can be argued that it is a valid tool for bus driver training to improve road safety. The purpose of this study then is to investigate whether there are significant differences between experienced and novice bus d...
The Advanced Photovoltaic and Electronics eXperiments (APEX) spacecraft, launched in August 1994, contained an Electrical Power Subsystem which included two 10 Common Pressure Vessel nickel hydrogen batteries manufactured by Eagle-Picher Industries, Inc. The spacecraft bus has fully supported over 18 months of on-orbit payload operations, well exceeding the mission requirement. Over the duration of the mission, three fundamentally different battery charging algorithms were used, as necessitat...
Schmidt, R.; Arends, H.; Pedersen, A.
A low and actively controlled electrostatic potential on the outer surfaces of a scientific spacecraft is very important for accurate measurements of cold plasma electrons and ions and the DC to low-frequency electric field. The Japanese/NASA Geotail spacecraft carriers as part of its scientific payload a novel ion emitter for active control of the electrostatic potential on the surface of the spacecraft. The aim of the ion emitter is to reduce the positive surface potential which is normally encountered in the outer magnetosphere when the spacecraft is sunlit. Ion emission clamps the surface potential to near the ambient plasma potential. Without emission control, Geotail has encountered plasma conditions in the lobes of the magnetotail which resulted in surface potentials of up to about +70 V. The ion emitter proves to be able to discharge the outer surfaces of the spacecraft and is capable of keeping the surface potential stable at about +2 V. This potential is measured with respect to one of the electric field probes which are current biased and thus kept at a potential slightly above the ambient plasma potential. The instrument uses the liquid metal field ion emission principle to emit indium ions. The ion beam energy is about 6 keV and the typical total emission current amounts to about 15 μA. Neither variations in the ambient plasma conditions nor operation of two electron emitters on Geotail produce significant variations of the controlled surface potential as long as the resulting electron emission currents remain much smaller than the ion emission current. Typical results of the active potential control are shown, demonstrating the surface potential reduction and its stability over time. 25 refs., 5 figs
Agrawan, A. K.; Mullen, P. G.; Vadakan, V. V.
Network bus adapter (NBA) handles protocols for computer-tocomputer communications. NBA does all protocol handling and communications with bus for its host computer, that processor of different speeds sends data to each other continuously at maximum speed. Any host can communicate with any other, or several or with all.
A Virginia school district has developed a curriculum of school bus safety objectives for each grade level (K-6). Produced as a complete package, the curriculum contains a lesson plan, expected outcomes, a listing of instructional aids, defined activities, and required student materials. Lists bus safety rules that are taught and those posted on…
Tofany, Vincent L.
The president of the National Safety Council suggests ways that parents can promote school bus safety, with emphasis on preventing accidents outside the bus. Parents can explain safety rules to their children and work with their parent teacher associations and school administrators to plan and enforce safety regulations. (PP)
This book is intended for developers, designers, and architects alike who wish to build C# NServiceBus enterprise architectures and learn how ESB persists data and messages to help them attain their goals. No prior knowledge of persistence in NServiceBus is required.
Carlos Andrés Ramos-Paja
Full Text Available In DC and hybrid microgrids (MG, the DC-bus regulation using Energy Storage Devices (ESD is important for the stable operation of both the generators and loads. There are multiple commercial voltage levels for both ESD and DC-bus; therefore, the ESD voltage may be higher, equal or lower than the DC-bus voltage depending on the application. Moreover, most of the ESD converter controllers are linear-based, hence they ensure stability in a limited operation range. This paper proposes a system to regulate the DC-bus voltage of an MG accounting for any voltage relation between the ESD and the DC-bus voltage. The proposed system is formed by an ESD connected to a DC-bus through a bidirectional Buck–Boost converter, which is regulated by a Sliding-Mode Controller (SMC to ensure the system stability in the entire operation range. The SMC drives the Buck–Boost charger–discharger to regulate the DC-bus voltage, at the desired reference value, by charging or discharging the ESD. This paper also provides detailed procedures to design the parameters of both the SMC and the charger–dischager. Finally, simulation and experimental results validate the proposed solution and illustrate its performance.
Sheen, Jyh-Jong; Bishop, Robert H.
The feedback linearization technique is applied to the problem of spacecraft attitude control and momentum management with control moment gyros (CMGs). The feedback linearization consists of a coordinate transformation, which transforms the system to a companion form, and a nonlinear feedback control law to cancel the nonlinear dynamics resulting in a linear equivalent model. Pole placement techniques are then used to place the closed-loop poles. The coordinate transformation proposed here evolves from three output functions of relative degree four, three, and two, respectively. The nonlinear feedback control law is presented. Stability in a neighborhood of a controllable torque equilibrium attitude (TEA) is guaranteed and this fact is demonstrated by the simulation results. An investigation of the nonlinear control law shows that singularities exist in the state space outside the neighborhood of the controllable TEA. The nonlinear control law is simplified by a standard linearization technique and it is shown that the linearized nonlinear controller provides a natural way to select control gains for the multiple-input, multiple-output system. Simulation results using the linearized nonlinear controller show good performance relative to the nonlinear controller in the neighborhood of the TEA.
Wolfgang, R.; Natarajan, T.; Day, J.
A feedback control system, called an auxiliary array switch, was designed to connect or disconnect auxiliary solar panel segments from a spacecraft electrical bus to meet fluctuating demand for power. A simulation of the control system was used to carry out a number of design and analysis tasks that could not economically be performed with a breadboard of the hardware. These tasks included: (1) the diagnosis of a stability problem, (2) identification of parameters to which the performance of the control system was particularly sensitive, (3) verification that the response of the control system to anticipated fluctuations in the electrical load of the spacecraft was satisfactory, and (4) specification of limitations on the frequency and amplitude of the load fluctuations.
Muhammad H. Al-Malack
Full Text Available Fuel oil flyash (FFA produced in power and water desalination plants firing crude oils in the Kingdom of Saudi Arabia is being disposed in landfills, which increases the burden on the environment, therefore, FFA utilization must be encouraged. In the current research, the effect of adding FFA on the engineering properties of two indigenous soils, namely sand and marl, was investigated. FFA was added at concentrations of 5%, 10% and 15% to both soils with and without the addition of Portland cement. Mixtures of the stabilized soils were thoroughly evaluated using compaction, California Bearing Ratio (CBR, unconfined compressive strength (USC and durability tests. Results of these tests indicated that stabilized sand mixtures could not attain the ACI strength requirements. However, marl was found to satisfy the ACI strength requirement when only 5% of FFA was added together with 5% of cement. When the FFA was increased to 10% and 15%, the mixture’s strength was found to decrease to values below the ACI requirements. Results of the Toxicity Characteristics Leaching Procedure (TCLP, which was performed on samples that passed the ACI requirements, indicated that FFA must be cautiously used in soil stabilization.
Federal Laboratory Consortium — FUNCTION: Provides the capability to correct unbalances of spacecraft by using dynamic measurement techniques and static/coupled measurements to provide products of...
Sørensen, Claus Hedegaard; Gudmundsson, Henrik
Act 2000, with the aim to modify some extreme effects of the initial deregulations. The second component includes reforms of how central government governs transport performance at the local level more generally through systems of Management by Objectives, performance control and economic incentives...... and an association of operators (three persons). A workshop was held in November 2007 in Manchester, where the authors discussed preliminary results from the analysis with representatives of GMPTE, GMPTA, bus operators and British research colleagues. Conclusions The following conclusions still are tentative...... motivator for partnering, and potentially for promoting more sustainable transport solutions All in all, New Public Management in the UK (outside of London) has so far been mostly negative for the implementation of sustainable transport....
This document describes a PCI bus simulator for use in evaluating the feasibility of system designs based on this bus.......This document describes a PCI bus simulator for use in evaluating the feasibility of system designs based on this bus....
Control units were connected to the channels with "Bus and Tag" cable pairs. The bus cables carried the address and data information and the tag cables identified what data was on the bus. There were three general types of bus-and-tag cables produced by IBM.
Full Text Available A Bayesian network is used to estimate revenues of bus services in consideration of the effect of bus travel demands, passenger transport distances, and so on. In this research, the area X in Beijing has been selected as the study area because of its relatively high bus travel demand and, on the contrary, unsatisfactory bus services. It is suggested that the proposed Bayesian network approach is able to rationally predict the probabilities of different revenues of various route services, from the perspectives of both satisfying passenger demand and decreasing bus operation cost. This way, the existing bus routes in the studied area can be optimized for their most probable high revenues.
An analysis of crash data shows that the number of fatal school bus related crashes has remained nearly constant over the past ten years, despite an increase in available safety-improving technology. One of the main concerns related to school bus safety is the issue of illegally passing a stopped school bus. To improve safety around stopped school buses, this dissertation presents a Concept of Operations for a connected vehicle application to improve safety around stopped school buses using D...
Increasing bicycle use and bus ridership are both desirable policy goals : from a sustainability standpoint, but on city streets these two modes of : transport are often in conflict. While occupying opposite ends of the size : and weight spectrum, th...
This report documents a motorcoach and school bus fire safety analysis performed by the John A. Volpe National Transportation Systems Center (Volpe) for the Federal Motor Carrier Safety Administration. This report aims to: 1) identify the causes, fre...
Bus transit agencies are required to hire extraboard (i.e. back-up) operators to account for unexpected absences. Incorrect sizing of extra driver workforce is problematic for a number of reasons. Overestimating the appropriate number of extraboard o...
This annual edition of Large Truck and Bus Crash Facts contains descriptive statistics about fatal, injury, and : property damage only crashes involving large trucks and buses in 2010. Selected crash statistics on passenger : vehicles are also presen...
This annual edition of Large Truck and Bus Crash Facts contains descriptive statistics about fatal, injury, and property damage only crashes involving large trucks and buses in 2012. Selected crash statistics on passenger vehicles are also presented ...
This annual edition of Large Truck and Bus Crash Facts contains descriptive statistics about fatal, injury, and property damage only crashes involving large trucks and buses in 2013. Selected crash statistics on passenger vehicles are also presented ...
This annual edition of Large Truck and Bus Crash Facts contains descriptive statistics about fatal, injury, and : property damage only crashes involving large trucks and buses in 2009. Selected crash statistics on passenger : vehicles are also presen...
This annual edition of Large Truck and Bus Crash Facts contains descriptive statistics about fatal, injury, and : property damage only crashes involving large trucks and buses in 2011. Selected crash statistics on passenger : vehicles are also presen...
Adverse weather significantly affects the United States national transportation system, including commercial companies : that rely on highways to support their enterprises. The Passenger Bus (Motorcoach) Industry (PBI) is one such affected : user who...
Gregor, P. J.
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.
With the introduction of 32 bit microprocessors several new 32 bit backplane bus architectures have been developed and are in the process for standardization. Among these are Future Bus (IEEE P896.1), VME-Bus (IEEE 1014), MULTIBUS II, Nu-Bus and Fastbus (IEEE 960). The paper describes and compares the main features of these bus architectures and mentions the status of national and international standardization efforts
The introduction of a tourist discovery bus in Gozo came about as a result of an EU Project which is part of the Interreg III B Archimed programmes in which the Islands and Small States Institute of the University of Malta participated. Other countries participating in this programme besides Malta, represented by the Islands and Small States Institute, are Italy, Cyprus and Greece. The discovery bus service was aimed at encouraging more tourists to come to Gozo and enabling them to visit stra...
Levis, J A
The paper describes the inter-relationship of anthropometry, rig studies and dynamic testing of aspects related to problems of the seated bus passenger. It seeks to draw together sub-sections of a very large study sponsored by the government through the Transport and Road Research Laboratory and undertaken by the Human Factors Group of Leyland Truck and Bus. It is relevant to all those designing passenger carrying transport systems.
Lian, Xuezheng; Wang, Haitao; Xie, Meilin; Huang, Wei; Li, Dawei; Jing, Feng
In the application of space satellite turntable, the design of balance wheel is very necessary. To solve the acquisition precision of Brushless DC motor speed is low, and the encoder is also more complex, this paper improves the original hall signal measurement methods. Using the logic device to achieve the six frequency multiplication of hall signal, the signal is used as speed feedback to achieve speed closed-loop control and improve the speed stability. At the same time, in order to prevent the E.M.F of BLDC motor to raise the voltage of the bus bar when reversing or braking, and affect the normal operation of other circuit modules, the analog circuit is used to protect the bus bar voltage by the way of energy consumption braking. The experimental results are consistent with the theoretical design, and the rationality and feasibility of the frequency multiplication scheme and bus voltage protection scheme are verified.
Full Text Available The control of bus voltage is a crucial task for the stable operation of islanded DC microgrids. To improve the DC bus voltage control dynamics and stability, this paper proposes an adaptive sliding-mode control method based on large-signal model. The sliding-mode control, adaptive observation, and fix-frequency pulse width modulation technology are adopted and combined efficiently, which guarantee stable bus voltage and the constant switching frequency of closed-loop system, regardless of how the parameters vary with the variable constant-power loads and uncertainties. In addition, the reference values can be quickly tracked by the state variables using the proposed method without any additional sensors/hardware circuits. Therefore, this method is beneficial for the scalability and plug-play of the distributed generators and loads within the DC microgrids. The performance of the proposed control method has been successfully verified in simulation.
Siswanto, Agus; Gunadin, Indar Chaerah; Said, Sri Mawar; Suyuti, Ansar
The purpose of this research is to improve the stability of interconnection of South Sulawesi system caused by penetration new wind turbine in Sidrap area on bus 2 and in Jeniponto area on bus 34. The method used in this research was via software Power System analysis Toolbox (PSAT) under MATLAB. In this research, there are two problems that are evaluated, the stability of the system before and after penetration wind turbine into the system South Sulawesi system. From the simulation result shows that penetration of wind turbine on bus 2 Sidrap, bus 37 Jeniponto give effect oscillation on the system. The oscillation was damped by installation of Power System Stabilizer (PSS) on bus 29 area Sungguminasa, that South Sulawesi system stable according to normal condition.
Leve, Frederick A; Peck, Mason A
The goal of this book is to serve both as a practical technical reference and a resource for gaining a fuller understanding of the state of the art of spacecraft momentum control systems, specifically looking at control moment gyroscopes (CMGs). As a result, the subject matter includes theory, technology, and systems engineering. The authors combine material on system-level architecture of spacecraft that feature momentum-control systems with material about the momentum-control hardware and software. This also encompasses material on the theoretical and algorithmic approaches to the control of space vehicles with CMGs. In essence, CMGs are the attitude-control actuators that make contemporary highly agile spacecraft possible. The rise of commercial Earth imaging, the advances in privately built spacecraft (including small satellites), and the growing popularity of the subject matter in academic circles over the past decade argues that now is the time for an in-depth treatment of the topic. CMGs are augmented ...
National Aeronautics and Space Administration — The objective of the Spacecraft Fire Safety Demonstration project is to develop and conduct large-scale fire safety experiments on an International Space Station...
National Aeronautics and Space Administration — This compilation of outgassing data of materials intended for spacecraft use were obtained at the Goddard Space Flight Center (GSFC), utilizing equipment developed...
This paper shows the effects of high PVintegration on the power system voltage stability. PV power plant was appliedto the IEEE 30 bus test system. Modal analysis method is used to show theeffect of PV integration on power system voltage stability. The power rate ofsynchronous generator in the IEEE 30 bus system is increased to show the powersystem stability effect of high PV penetration and then the PV generation withthe same power rate is connected appropriate bus in power system. The modal...
Muller, T.; Knoppers, P.; Mols, B.
With no hard data on route times to go on, bus companies find it impossible to optimise their timetables. The result is that buses arrive needlessly late, and in some cases even pass their stops ahead of schedule, which is even more frustrating to waiting passengers. "I was at the bus stop on time,
This report presents 16 case studies of attacks planned or carried out against Israeli bus targets, along with statistical data on the number, frequency, and lethality of attacks against bus targets that have taken place in Israel since 1970 and duri...
Bai, Cong; Peng, Zhong-Ren; Lu, Qing-Chang; Sun, Jian
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.
Bai, Cong; Peng, Zhong-Ren; Lu, Qing-Chang; Sun, Jian
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
Milla, Freddy; Duarte-Mermoud, Manuel A
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. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.
Chatterjee, Atanu; Manohar, Manju; Ramadurai, Gitakrishnan
In this paper, we model the bus networks of six major Indian cities as graphs in L-space, and evaluate their various statistical properties. While airline and railway networks have been extensively studied, a comprehensive study on the structure and growth of bus networks is lacking. In India, where bus transport plays an important role in day-to-day commutation, it is of significant interest to analyze its topological structure and answer basic questions on its evolution, growth, robustness and resiliency. Although the common feature of small-world property is observed, our analysis reveals a wide spectrum of network topologies arising due to significant variation in the degree-distribution patterns in the networks. We also observe that these networks although, robust and resilient to random attacks are particularly degree-sensitive. Unlike real-world networks, such as Internet, WWW and airline, that are virtual, bus networks are physically constrained. Our findings therefore, throw light on the evolution of such geographically and constrained networks that will help us in designing more efficient bus networks in the future.
Meza, Luis; Tung, Frank; Anandakrishnan, Satya; Spector, Victor; Hyde, Tupper
The James Webb Space Telescope (JWST) builds upon the successful flight experience of the Chandra Xray Telescope by incorporating an additional LOS pointing servo to meet the more stringent pointing requirements. The LOS pointing servo, referred to in JWST as the Fine Guidance Control System (FGCS), will utilize a Fine Guidance Sensor (FGS) as the sensor, and a Fine Steering Mirror (FSM) as the actuator. The FSM is a part of the Optical Telescope Element (OTE) and is in the optical path between the tertiary mirror and the instrument focal plane, while the FGS is part of the Integrated Science Instrument Module (ISIM). The basic Chandra spacecraft bus attitude control and determination architecture, utilizing gyros, star trackers/aspect camera, and reaction wheels, is retained for JWST. This system has achieved pointing stability of better than 0.5 arcseconds. To reach the JWST requirements of milli-arcsecond pointing stability with this ACS hardware, the local FGCS loop is added to the optical path. The FGCS bandwidth is about 2.0 Hz and will therefore attenuate much of the spacecraft ACS induced low frequency jitter. In order to attenuate the higher frequency (greatet than 2.0 Hz) disturbances associated with reaction wheel static and dynamic imbalances, as well as bearing run-out, JWST will employ a two-stage passive vibration isolation system consisting of (1) 7.0 Hz reaction wheel isolators between each reaction wheel and the spacecraft bus, and (2) a 1.0 Hz tower isolator between the spacecraft bus and the Optical Telescope Element (OTE). In order to sense and measure the LOS, the FGS behaves much like an autonomous star tracker that has a very small field of view and uses the optics of the telescope. It performs the functions of acquisition, identification and tracking of stars in its 2.5 x 2.5 arcminute field of view (FOV), and provides the centroid and magnitude of the selected star for use in LOS control. However, since only a single star is being tracked
Full Text Available The KOMPSAT (KOrea Multi-Purpose SATellite has two optical imaging instruments called EOC (Electro-Optical Camera and OSMI (Ocean Scanning Multispectral Imager. The image data of these instruments are transmitted to ground station and restored correctly after post-processing with the telemetry data transferred from KOMPSAT spacecraft. The major timing information of the KOMPSAT is OBT (On-Board Time which is formatted by the on-board computer of the spacecraft, based on 1Hz sync. pulse coming from the GPS receiver involved. The OBT is transmitted to ground station with the house-keeping telemetry data of the spacecraft while it is distributed to the instruments via 1553B data bus for synchronization during imaging and formatting. The timing information contained in the spacecraft telemetry data would have direct relation to the image data of the instruments, which should be well explained to get a more accurate image. This paper addresses the timing analysis of the KOMPSAT spacecraft and instruments, including the gyro data timing analysis for the correct restoration of the EOC and OSMI image data at ground station.
In the spring of 1962, engineers from the Engineering Mechanics Division of the Jet Propulsion Laboratory gave a series of lectures on spacecraft design at the Engineering Design seminars conducted at the California Institute of Technology. Several of these lectures were subsequently given at Stanford University as part of the Space Technology seminar series sponsored by the Department of Aeronautics and Astronautics. Presented here are notes taken from these lectures. The lectures were conceived with the intent of providing the audience with a glimpse of the activities of a few mechanical engineers who are involved in designing, building, and testing spacecraft. Engineering courses generally consist of heavily idealized problems in order to allow the more efficient teaching of mathematical technique. Students, therefore, receive a somewhat limited exposure to actual engineering problems, which are typified by more unknowns than equations. For this reason it was considered valuable to demonstrate some of the problems faced by spacecraft designers, the processes used to arrive at solutions, and the interactions between the engineer and the remainder of the organization in which he is constrained to operate. These lecture notes are not so much a compilation of sophisticated techniques of analysis as they are a collection of examples of spacecraft hardware and associated problems. They will be of interest not so much to the experienced spacecraft designer as to those who wonder what part the mechanical engineer plays in an effort such as the exploration of space.
Lukash, James A.; Daley, Earl
This work describes the design and development effort to adapt rapid-development space hardware by creating a ground system using solutions of low complexity, mass, & cost. The Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft is based on the modular common spacecraft bus architecture developed at NASA Ames Research Center. The challenge was building upon the existing modular common bus design and development work and improving the LADEE spacecraft design by adding an Equipotential Voltage Reference (EVeR) system, commonly referred to as a ground system. This would aid LADEE in meeting Electromagnetic Environmental Effects (E3) requirements, thereby making the spacecraft more compatible with itself and its space environment. The methods used to adapt existing hardware are presented, including provisions which may be used on future spacecraft.
This thesis describes the development of an attitude determination system for spacecraft based only on magnetic field measurements. The need for such system is motivated by the increased demands for inexpensive, lightweight solutions for small spacecraft. These spacecraft demands full attitude...... determination based on simple, reliable sensors. Meeting these objectives with a single vector magnetometer is difficult and requires temporal fusion of data in order to avoid local observability problems. In order to guaranteed globally nonsingular solutions, quaternions are generally the preferred attitude...... is a detailed study of the influence of approximations in the modeling of the system. The quantitative effects of errors in the process and noise statistics are discussed in detail. The third contribution is the introduction of these methods to the attitude determination on-board the Ørsted satellite...
Feng, Shumin; Li, Zhenning; Ci, Yusheng; Zhang, Guohui
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. Copyright © 2015 Elsevier Ltd. All rights reserved.
Robinson, D; Griffith, J; McComish, K; Swasbrook, K
The effectiveness of a program combining classroom and community training in the teaching of bus-riding skills to developmentally disabled adults. These skills were taught sequentially using questions about a slide presentation, role playing, and performance in the natural environment. The experimental design was based upon the work of Neef, Iwata, and Page (1978). Test trials were conducted after each phase of training. Results showed that all subjects learned the necessary bus-riding skills and maintained their performance throughout the follow-up period of at least 1 year. The combination training method proved to be efficient and cost effective.
We study the dynamical behavior of a shuttle bus moving through a traffic signal. The dynamics of the bus is expressed in terms of the nonlinear maps. The bus dynamics is controlled by varying the loading parameter, the cycle time of signal, and the degree of speedup. We show the dependence of the tour time on both loading parameter and cycle time. The fluctuation of boarding passengers is highly reduced by varying the cycle time. When the bus speeds up to retrieve the delay induced by loading the passengers, the bus behavior also changes highly. The shuttle bus schedule is connected with the complex motion of the shuttle bus. The region map (phase diagram) is shown to control the complex motion of the bus.
Kompier, M.A.J.; Aust, B.; Berg, A.M. van den; Siegrist, J.
The research aim was to select, compare, and analyze interventions and preventive actions from international bus companies to decrease bus drivers' occupational stress and sickness absenteeism. Through networking, international surveys, and literature study, 13 "natural experiments" were identified
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 report discusses the planned fuel cell bus demonstration and equipment us...
Full Text Available With the development of city, the problem of traffic is becoming more and more serious. Developing public transportation has become the key to solving this problem in all countries. Based on the existing public transit network, how to improve the bus operation efficiency, and reduce the residents transit trip cost has become a simple and effective way to develop the public transportation. Bus stop spacing is an important factor affecting passengers’ travel time. How to set up bus stop spacing has become the key to reducing passengers’ travel time. According to comprehensive traffic survey, theoretical analysis, and summary of urban public transport characteristics, this paper analyzes the impact of bus stop spacing on passenger in-bus time cost and out-bus time cost and establishes in-bus time and out-bus time model. Finally, the paper gets the balance best station spacing by introducing the game theory.
Full Text Available This invention relates to a wireless bus information management system, which includes bus stop and vehicle management subsystems. The management signals are transmittable between bus stops and the vehicle. Based on vehicle management signals, the bus stop management subsystem can obtain information about the bus route identification, the number of unoccupied seats, the intention to stop or not, etc. Similarly, with the bus stop management signals, the vehicle management subsystem can make the decision of stopping. Accordingly, when a passenger wants to get off the vehicle or there are unoccupied seats, the vehicle management subsystem will inform the bus stop management subsystem such that the passengers waiting at the bus stop may flexibly schedule their travel plan. The proposed distributed wireless system is detailed by a prototype implementation and a simulation analysis, which is shown to be feasible and scalable.
The EPOXI flight mission has been testing a new commercial system, Splunk, which employs data mining techniques to organize and present spacecraft telemetry data in a high-level manner. By abstracting away data-source specific details, Splunk unifies arbitrary data formats into one uniform system. This not only reduces the time and effort for retrieving relevant data, but it also increases operational visibility by allowing a spacecraft team to correlate data across many different sources. Splunk's scalable architecture coupled with its graphing modules also provide a solid toolset for generating data visualizations and building real-time applications such as browser-based telemetry displays.
Government regulators and transportation operators of public bus systems are concerned about terrorist attacks. Bus attacks in Israel between late September 2000 and the end of 2006, a period known as the Second Intifada, are particularly well known....
National Aeronautics and Space Administration — Design of a my single person reusable spacecraft. It can carry one person and it has to be dropped from an aircraft at an altitude of 40,000 - 45,000 feet. Can be...
... Availability on June 24, 2011. The SGR Initiative makes funds available to public transit providers to finance capital projects to replace, rehabilitate, and purchase buses and related equipment and to construct bus...
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...
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…
Proposed rules by the U.S. Department of Transportation (DOT) for drug and alcohol testing of school bus drivers are expected to be implemented by early 1994. DOT regulations are very specific. School districts need to decide whether to establish their own program or contract with a full-service drug-testing firm. Explains the seven major elements…
Full Text Available Nowadays, with highly developed instrumentation, sensing and actuation technologies, it is possible to foresee an important advance in the field of autonomous and/or semi-autonomous transportation systems. Intelligent Transport Systems (ITS have been subjected to very active research for many years, and Bus Rapid Transit (BRT is one area of major interest. Among the most promising transport infrastructures, the articulated bus is an interesting, low cost, high occupancy capacity and friendly option. In this paper, an experimental platform for research on the automatic control of an articulated bus is presented. The aim of the platform is to allow full experimentation in real conditions for testing technological developments and control algorithms. The experimental platform consists of a mobile component (a commercial articulated bus fully instrumented and a ground test area composed of asphalt roads inside the Consejo Superior de Investigaciones Científicas (CSIC premises. This paper focuses also on the development of a human machine interface to ease progress in control system evaluation. Some experimental results are presented in order to show the potential of the proposed platform.
Eudy, Leslie [National Renewable Energy Laboratory (NREL), Golden, CO (United States)
This presentation describing the FY 2016 accomplishments for the National Renewable Energy Laboratory's Fuel Cell Bus Evaluations project was presented at the U.S. Department of Energy Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting, June 7, 2016.
Illinois State Board of Education, Springfield.
Four units are provided for formal classroom instruction in advanced competencies for school bus drivers in Illinois. Units cover passenger control, accidents and emergencies, detecting hazards, and first aid. Each unit contains some or all of the following components: table of contents; a list of objectives; informative material, including an…
Successful school bus drivers bring much more than mechanical know-how to the job. They develop good rapport with students while acting to bring undesirable student behavior under control. Drivers must also show an interest in students' welfare and have a good sense of humor. (MLH)
Oshyani, M.F.; Cats, O.
Bus travel times are subject to inherent and recurrent uncertainties. A real-time prediction scheme regarding how the transit system evolves will potentially facilitate more adaptive operations as well as more adaptive passengers’ decisions. This scheme should be tractable, sufficiently fast and
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.
Full Text Available The increasing number of road user causing traffic jam finds out a way, busway. However, in its implementation, the number of fleet available does not enough to take the passengers. It results in the an amassed of passengers at several bus stops. This leads to passenger dissatisfaction satisfaction which eventually causes Transjakarta users to reuse private cars. Definitely this situation may builds up traffic jams. Stochastic Bus Dispatching Model is used to simulate public transportation that operates regularly.
Full Text Available The eGov-Bus project provides citizens and businesses with improved access to virtual public services, which are based on existing national eGovernment Web services and which support cross-border life events. Requirements and specific rules of these life events are considered, and personalization of user preferences is supported. eGov-Bus is based on adaptable process management technologies, allowing for virtual services which are dynamically combined from existing national eGovernment services. In this way, a comprehensive workflow process is set up, allowing for service-level agreements, an audit trail and explanation of the process to the end user. The eGov-Bus process engine operates on top of a virtual repository, providing a high-level semantic view of information retrieved from heterogeneous information sources, such as eGovernment Web services. Further, eGov-Bus relies on a security framework to ensure all high-level security requirements are met. The eGov-Bus architecture is business oriented, it focuses on Service Oriented Architecture (SOA concepts, asynchronously combining Web services and providing a Service Bus.
Fassa, Ferdinand; Sitorus, Fredy Jhon Philip; Adikesuma, Tri Nugraha
Around the world, shuttle bus operation played the significant role to accommodate transportation for commuting bus passengers. Shuttle Bus services in cities are provided by various bus agencies with kinds of own specific purposes. For instance, at Tangerang Selatan, Indonesia, it was said that shuttle bus In Trans Bintaro is run and operated by private bus companies hire by Bintaro developer. The aim of this research is to identify factors of satisfaction of shuttle bus service in Kota Tangerang Selatan, Indonesia. Several factors are used to analyze sums of 20 parameters performance indicators of Shuttle Bus. A face to face interview using a questionnaire (N=200) was used to collect data on October and March 2017. Likert and diagram Cartesian were used to model the all the parameters. This research succeeded in finding some categories of Shuttle bus service attributes such as accessibility, comfort, and safety. Users agreed that eight indicators in shuttle bus have the excellent achievement, while three indicators on performance remain low and should receive more attention especially punctuality of the bus.
Johnson, Lee; De Soria-Santacruz Pich, Maria; Conroy, David; Lobbia, Robert; Huang, Wensheng; Choi, Maria; Sekerak, Michael J.
NASA's Asteroid Redirect Robotic Mission (ARRM) project plans included a set of plasma and space environment instruments, the Plasma Diagnostic Package (PDP), to fulfill ARRM requirements for technology extensibility to future missions. The PDP objectives were divided into the classes of 1) Plasma thruster dynamics, 2) Solar array-specific environmental effects, 3) Plasma environmental spacecraft effects, and 4) Energetic particle spacecraft environment. A reference design approach and interface requirements for ARRM's PDP was generated by the PDP team at JPL and GRC. The reference design consisted of redundant single-string avionics located on the ARRM spacecraft bus as well as solar array, driving and processing signals from multiple copies of several types of plasma, effects, and environments sensors distributed over the spacecraft and array. The reference design sensor types were derived in part from sensors previously developed for USAF Research Laboratory (AFRL) plasma effects campaigns such as those aboard TacSat-2 in 2007 and AEHF-2 in 2012.
Dakermanji, George; Lee, Leonine; Spitzer, Thomas
The Global Precipitation Measurement (GPM) spacecraft was jointly developed by NASA and JAXA. It is a Low Earth Orbit (LEO) spacecraft launched on February 27, 2014. The power system is a Direct Energy Transfer (DET) system designed to support 1950 watts orbit average power. The batteries use SONY 18650HC cells and consist of three 8s by 84p batteries operated in parallel as a single battery. During instrument integration with the spacecraft, large current transients were observed in the battery. Investigation into the matter traced the cause to the Dual-Frequency Precipitation Radar (DPR) phased array radar which generates cyclical high rate current transients on the spacecraft power bus. The power system electronics interaction with these transients resulted in the current transients in the battery. An accelerated test program was developed to bound the effect, and to assess the impact to the mission.
Full Text Available This paper describes a research on The Flexible Bus Systems (FBS using Zigbee as a communication medium. The Flexible Bus System is a demand responsive transit (DRT which is more efficient and convenient in a sense that it entertains passenger’s demands and gives bus locations in real time. The real time synchronization of The Flexible Bus System makes it information rich and unique as compared to other DRTs. The Flexible Bus Systems is a system that can replace the Traditional Bus Systems with its flexibility and efficiency. This paper discusses the use of wireless technologies in The Flexible Bus Systems and how to make it more reliable using short range wireless technology Zigbee.
Prato, Carlo Giacomo; Kaplan, Sigal
Purpose Bus safety is a concern not only in developing countries, but also in the U.S. and Europe. In Denmark, disentangling risk factors that are positively or negatively related to bus accident severity and injury occurrence to bus passengers can contribute to promote safety as an essential...... examining occurrence of injury to bus passengers. Results Bus accident severity is positively related to (i) the involvement of vulnerable road users, (ii) high speed limits, (iii) night hours, (iv) elderly drivers of the third party involved, and (v) bus drivers and other drivers crossing in yellow or red...... light. Occurrence of injury to bus passengers is positively related to (i) the involvement of heavy vehicles, (ii) crossing intersections in yellow or red light, (iii) open areas, (iv) high speed limits, and (v) slippery road surface. Conclusions The findings of the current study provide a comprehensive...
Wihartiko, F. D.; Buono, A.; Silalahi, B. P.
Bus timetable gave an information for passengers to ensure the availability of bus services. Timetable optimal condition happened when bus trips frequency could adapt and suit with passenger demand. In the peak time, the number of bus trips would be larger than the off-peak time. If the number of bus trips were more frequent than the optimal condition, it would make a high operating cost for bus operator. Conversely, if the number of trip was less than optimal condition, it would make a bad quality service for passengers. In this paper, the bus timetabling problem would be solved by integer programming model with modified genetic algorithm. Modification was placed in the chromosomes design, initial population recovery technique, chromosomes reconstruction and chromosomes extermination on specific generation. The result of this model gave the optimal solution with accuracy 99.1%.
Mathieu, Charlotte; Weigel, Annalisa
The report introduces the concept of spacecraft fractionation, which transforms a traditional monolithic spacecraft into a network of elements where a free-flying payload module is supported by nearby...
Dr. Patrick O'Neill, NASA Johnson Space Center, will present a detailed description of the radiation environment inside spacecraft. The free space (outside) solar and galactic cosmic ray and trapped Van Allen belt proton spectra are significantly modified as these ions propagate through various thicknesses of spacecraft structure and shielding material. In addition to energy loss, secondary ions are created as the ions interact with the structure materials. Nuclear interaction codes (FLUKA, GEANT4, HZTRAN, MCNPX, CEM03, and PHITS) transport free space spectra through different thicknesses of various materials. These "inside" energy spectra are then converted to Linear Energy Transfer (LET) spectra and dose rate - that's what's needed by electronics systems designers. Model predictions are compared to radiation measurements made by instruments such as the Intra-Vehicular Charged Particle Directional Spectrometer (IV-CPDS) used inside the Space Station, Orion, and Space Shuttle.
Chow, Joe Hong; Ghiocel, Scott Gordon
In steady-state voltage stability analysis, as load increases toward a maximum, conventional Newton-Raphson power flow Jacobian matrix becomes increasingly ill-conditioned so power flow fails to converge before reaching maximum loading. A method to directly eliminate this singularity reformulates the power flow problem by introducing an AQ bus with specified bus angle and reactive power consumption of a load bus. For steady-state voltage stability analysis, the angle separation between the swing bus and AQ bus can be varied to control power transfer to the load, rather than specifying the load power itself. For an AQ bus, the power flow formulation is only made up of a reactive power equation, thus reducing the size of the Jacobian matrix by one. This reduced Jacobian matrix is nonsingular at the critical voltage point, eliminating a major difficulty in voltage stability analysis for power system operations.
Chandra, A.K.; Ganesh, G.; Mayya, Anuradha; Chachondia, A.S.; Premraj, M.K.
Several operator information systems for nuclear plants has been developed in the Division and these have involved extensive use of microcomputer boards for achieving various functions. Standard VME bus based boards have been developed to provide the most used functions. These boards have been fabricated and tested and used in several systems including Channel Temperature Monitoring systems, Disturbance Recording Systems etc. and are also proposed to be used in additional systems under developement. The use of standard bus and boards provides considerable savings in engineering time, prototyping, testing and evaluation costs, and maintenance support. This report desribes the various boards developed and the functions available on each. (author). 4 refs., 11 figs., 3 appendixes
Full Text Available The goal of this study was to measure ultrafine particle concentrations with diameters less than 1 ÃŽÂ¼m emitted by diesel buses and to assess resulting human exposure levels. The study was conducted at the Woolloongabba Busway station in Brisbane, Australia in the winter months of 2002 during which temperature inversions frequently occurred. Most buses that utilize the station are fuelled by diesel, the exhaust of which contains a significant quantity of particle matter. Passengers waiting at the station are exposed to these particles emitted from the buses. During the course of this study, passenger census was conducted, based on video surveillance, yielding person-by-person waiting time data. Furthermore, a bus census revealed accurate information about the total number of diesel versus Compressed Natural Gas (CNG powered buses. Background (outside of the bus station and platform measurements of ultrafine particulate number size distributions were made to determine ambient aerosol concentrations. Particle number exposure concentration ranges from 10 and 40 to 60% of bus related exhaust fumes. This changes dramatically when considering the particle mass exposure concentration, where most passengers are exposed to about 50 to 80% of exhaust fumes. The obtained data can be very significant for comparison with similar work of this type because it is shown in previous studies that exhaust emissions causes cancer in laboratory animals. It was assumed that significant differences between platform and background distributions were due to bus emissions which, combined with passenger waiting times, yielded an estimate of passenger exposure to ultrafine particles from diesel buses. From an exposure point of view, the Busway station analyzed resembles a street canyon. Although the detected exhaust particle concentration at the outbound platform is found to be in the picogram range, exposure increases with the time passengers spend on the platform
Schlosser, Tibor; Schlosser, Peter; Cápayová, Silvia; Hodáková, Dominika
The main objective of this article is to describe the strategy for development of the public transport terminals in the city of Bratislava, Capital of Slovak Republic. The reason goes from the private operator Slovak Lines, who operates the suburb bus transport in the agglomeration of the city. For this operator was created a transport model, while placing emphasis on optimizing the compliance of suburban public transport with urban public transport in the city of Bratislava and evaluating the significance of the new Bus Station to be constructed at Mlynské Nivy - in a new down town centre of the city. The main issue is to ensure the best available offer of public transport (PT) to passengers in the Bratislava agglomeration. The subject of the study was oriented to specify and propose changes in the transport infrastructure and integrated public transport organisation on the area of the city in terms of the significant position of the new Mlynské Nivy Bus Station (MN BS), which is under preparation with realization in the year 2017.
This project analyzed the feasibility of placing an electrostatic field around a spacecraft to provide a shield against radiation. The concept was originally proposed in the 1960s and tested on a spacecraft by the Soviet Union in the 1970s. Such tests and analyses showed that this concept is not only feasible but operational. The problem though is that most of this work was aimed at protection from 10- to 100-MeV radiation. We now appreciate that the real problem is 1- to 2-GeV radiation. So, the question is one of scaling, in both energy and size. Can electrostatic shielding be made to work at these high energy levels and can it protect an entire vehicle? After significant analysis and consideration, an electrostatic shield configuration was proposed. The selected architecture was a torus, charged to a high negative voltage, surrounding the vehicle, and a set of positively charged spheres. Van de Graaff generators were proposed as the mechanism to move charge from the vehicle to the torus to generate the fields necessary to protect the spacecraft. This design minimized complexity, residual charge, and structural forces and resolved several concerns raised during the internal critical review. But, it still is not clear if such a system is costeffective or feasible, even though several studies have indicated usefulness for radiation protection at energies lower than that of the galactic cosmic rays. Constructing such a system will require power supplies that can generate voltages 10 times that of the state of the art. Of more concern is the difficulty of maintaining the proper net charge on the entire structure and ensuring that its interaction with solar wind will not cause rapid discharge. Yet, if these concerns can be resolved, such a scheme may provide significant radiation shielding to future vehicles, without the excessive weight or complexity of other active shielding techniques.
Carpenter, James Russell; Bauer, Frank H. (Technical Monitor)
A fundamental issue for estimation and control of distributed systems such as formation flying spacecraft is the information exchange architecture. In centralized schemes, each subordinate need only share its measurement data with a central hub, and the subordinates depend on the center to direct their actions. In decentralized schemes, all nodes participate in the data exchange, so that each has the same in by formation as the center, and may thereby self-direct the same action that the center would have commanded, assuming all share a common goal. This talk compares and contrasts the centralized and decentralized schemes in the context of autonomously maintaining a distributed satellite formation.
Pike, C. P. (Editor); Lovell, R. R. (Editor)
Over 50 papers from the spacecraft charging conference are included on subjects such as: (1) geosynchronous plasma environment, (2) spacecraft modeling, (3) spacecraft materials characterization, (4) spacecraft materials development, and (5) satellite design and test.
Full Text Available The paper presents a logic synthesis procedure pneumatic control of the door of the bus for suburban traffic. Minimization of pneumatic control is determined graphically by Weitz – Carnot method. It also shows all pneumatic components belonging to installations used for opening and closing the door of the bus. Finally it is shown the basic maintenance of pneumatic system of the bus door.
Harahap, Rabiah Z
Bus is the one of transportation which is often used by society. Society as passenger of bus righteously gains protection. Many of accident happens in public transportation especially bus that rises a question the important of protection for people as the accicent victim. This question is worthy to be solved because many of public transportation company ignores the passenger's right. Based on this, government shall take control with presentation of new regulation that aims protection people ...
Qiu, Zhaowen; Li, Xiaoxia; Hao, Yanzhao; Deng, Shunxi; Gao, H Oliver
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.
Li Yuanhong; Zhang Quanzhu; Zhang Wenshan
Based on CAN bus, this paper studies the system control and management system of locomotive in mine, analyzes the working principle of locomotive system, gives the CAN bus scheme, hardware circuit design and CAN communication protocol, and implements long-distance, high-reliability communication function and remote monitoring function. Experiments show that the auxiliary system based on CAN bus control easier, operation more secure, as well as improving the control performance and service lif...
The possibility of inter-spacecraft collisions is a serious concern at Geosynchronous altitudes, where many high-value assets operate in proximity to countless debris objects whose orbits experience no natural means of decay. The ability to rendezvous with these derelict satellites would enable active debris removal by servicing or repositioning missions, but docking procedures are generally inhibited by the large rotational momenta of uncontrolled satellites. Therefore, a contactless means of reducing the rotation rate of objects in the space environment is desired. This dissertation investigates the viability of Coulomb charging to achieve such remote spacecraft attitude control. If a servicing craft imposes absolute electric potentials on a nearby nonspherical debris object, it will impart electrostatic torques that can be used to gradually arrest the object's rotation. In order to simulate the relative motion of charged spacecraft with complex geometries, accurate but rapid knowledge of the Coulomb interactions is required. To this end, a new electrostatic force model called the Multi-Sphere Method (MSM) is developed. All aspects of the Coulomb de-spin concept are extensively analyzed and simulated using a system with simplified geometries and one dimensional rotation. First, appropriate control algorithms are developed to ensure that the nonlinear Coulomb torques arrest the rotation with guaranteed stability. Moreover, the complex interaction of the spacecraft with the plasma environment and charge control beams is modeled to determine what hardware requirements are necessary to achieve the desired electric potential levels. Lastly, the attitude dynamics and feedback control development is validated experimentally using a scaled down terrestrial testbed. High voltage power supplies control the potential on two nearby conductors, a stationary sphere and a freely rotating cylinder. The nonlinear feedback control algorithms developed above are implemented to
With the rapid development of new energy vehicle technology, new energy bus has become more and more popular in China, and the relevant standards and policy are urgently needed to guide the market. According to the assessment of the development situation on new energy vehicle technology and new energy bus, combing with traffic policy guidance and the development trend of new energy vehicles, this paper aims to put forward the countermeasures of the new energy bus standard in China, including standard system, key standards and relevant recommendations. Research result is expected to provide decision support for the wide application of new energy bus in China.
Full Text Available Limited number of berths can result in a subsequent bus stopping at the upstream of a bus stop when all berths are occupied. When this traffic phenomenon occurs, passengers waiting on the platform usually prefer walking to the stopped bus, which leads to additional walking time before boarding the bus. Therefore, passengers’ travel time consumed at a bus stop is divided into waiting time, additional walking time, and boarding time. This paper proposed a mathematical model for analyzing passengers’ travel time at conventional bus stop based on theory of stochastic service system. Field-measured and simulated data were designated to demonstrate the effectiveness of the proposed model. By analyzing the results, conclusion was conducted that short headway can reduce passengers’ waiting time at bus stop. Meanwhile, the theoretical analysis explained the inefficiency of bus stops with more than three berths from the perspective of passengers’ additional walking time. Additional walking time will increase in a large scale when the number of berths at a bus stop exceedsthe threshold of three.
Klem, B.; Swann, D.
from both the sun and the underlying earth surface. The objects are modeled to be either tumbling or spin stabilized at key orientations in order to capture the complexity of the solar/earth incident illumination and the sensor viewing aspect conditions. Although these geometries and processes appear to be specialized and limited, they are sufficient to capture the principal observable features that are necessary for gaining insight into the complex issues of interpreting non-imaging sensor signals for monitoring the actual on-orbit spacecraft behavior changes. This talk has been prepared as a poster paper, to allow for engagement with conference participants on the presentation contents, and discussions for expansion of the material to include additional topical areas for future work, as appropriate. All discussions have been limited only to topics that could be discussed in the open format of the conference.
American Federation of Teachers (NJ), 2007
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…
... availability on June 27, 2011. The Bus Livability program makes funds available to public transit providers to finance capital projects to replace, rehabilitate, and purchase buses and related equipment and to... analyses. The Alternatives Analysis Program assists potential sponsors of major transit capital investments...
Ren, Yibin; Chen, Ge; Han, Yong; Zheng, Huangcheng
Customized City Bus Service (CCBS) can reduce the traffic congestion and environmental pollution that caused by the increasing in private cars, effectively. This study aims to extract the potential bus lines and each line's passenger density of CCBS by mining the public transport big data. The datasets used in this study are mainly Smart Card Data (SCD) and bus GPS data of Qingdao, China, from October 11th and November 7th 2015. Firstly, we compute the temporal-origin-destination (TOD) of passengers by mining SCD and bus GPS data. Compared with the traditional OD, TOD not only has the spatial location, but also contains the trip's boarding time. Secondly, based on the traditional DBSCAN algorithm, we put forwards an algorithm, named TOD-DBSCAN, combined with the spatial-temporal features of TOD.TOD-DBSCAN is used to cluster the TOD trajectories in peak hours of all working days. Then, we define two variables P and N to describe the possibility and passenger destiny of a potential CCBS line. P is the probability of the CCBS line. And N represents the potential passenger destiny of the line. Lastly, we visualize the potential CCBS lines extracted by our procedure on the map and analyse relationship between potential CCBS lines and the urban spatial structure.
Gunawan Fergyanto E.
Full Text Available 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.
Schmutz, Guido; van Zoggel, Jan
This cookbook is full of immediately useable recipes showing you how to develop service and message-oriented (integration) applications on the Oracle Service Bus. In addition to its cookbook style, which ensures the solutions are presented in a clear step-by-step manner, the explanations go into great detail, which makes it good learning material for everyone who has experience in OSB and wants to improve. Most of the recipes are designed in such a way that each recipe is presented as a separate, standalone entity and reading of prior recipes is not required. The finished solution of each reci
Mardi Safitri, Dian; Azmi, Nora; Singh, Gurbinder; Astuti, Pudji
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
Johar, Amita; Jain, S. S.; Garg, P. k.
An efficient public transportation system is essential of any country. The growth, development and shape of the urban areas are mainly due to availability of good transportation (Shah et al. in Inst Town Plan India J 5(3):50-59, 1). In developing countries, like India, travel by local bus in a city is very common. The accidents, congestion, pollution and appropriate location of bus stops are the major problems arising in metropolitan cities. Among all the metropolitan cities in India, Delhi has highest percentage of growth of population and vehicles. Therefore, it is important to adopt efficient and effective ways to improve mobility in different metropolitan cities in order to overcome the problem and to reduce the number of private vehicles on the road. The primary objective of this paper is to present a methodology for developing a model for optimum bus stop spacing (OBSS). It describes the evaluation of existing urban bus route, data collection, development of model for optimizing urban bus route and application of model. In this work, the bus passenger generalized cost method is used to optimize the spacing between bus stops. For the development of model, a computer program is required to be written. The applicability of the model has been evaluated by taking the data of urban bus route of Delhi Transport Corporation (DTC) in Excel sheet in first phase. Later on, it is proposed to develop a programming in C++ language. The developed model is expected to be useful to transport planner for rational design of the spacing of bus stops to save travel time and to generalize operating cost. After analysis it is found that spacing between the bus stop comes out to be between 250 and 500 m. The Proposed Spacing of bus stops is done considering the points that they don't come nearer to metro/rail station, entry or exit of flyover and near traffic signal.
Nagatani, Takashi; Naito, Yuichi
We have studied the dynamic behavior of a bus in the shuttle bus transportation with a periodic inflow. A bus schedule is closely related to the dynamics. We present the modified circle map model for the dynamics of the shuttle bus. The motion of the shuttle bus depends on the loading parameter and the inflow period. The shuttle bus displays the periodic, quasi-periodic, and chaotic motions with varying both loading parameter and inflow rate.
Zhao, Shuzhi; Lu, Chunxiu; Liang, Shidong; Liu, Huasheng
Bus bunching is one of the most serious problems of urban bus systems. Bus bunching increases waiting and travel time of passengers. Many bus systems use schedules to reach equal headways. Compared to the idea of schedules and the target headway introduced later, we propose a new method to improve the efficiency of a bus system and avoid bus bunching by boarding limits. Our solution can be effectively implemented when buses cannot travel as planned because of bad road conditions and dynamic d...
Roberts, T. M.; Lynch, K. A.; Clayton, R. E.; Weiss, J.; Hampton, D. L.
Measurement of ionospheric plasma is often performed by a single in situ device or remotely using cameras and radar. This article describes a small, low-resource, deployed spacecraft used as part of a local, multipoint measurement network. A B-field aligned sounding rocket ejects four of these spin-stabilized spacecraft in a cross pattern. In this application, each spacecraft carries two retarding potential analyzers which are used to determine plasma density, flow, and ion temperature. An inertial measurement unit and a light-emitting diode array are used to determine the position and orientation of the devices after deployment. The design of this spacecraft is first described, and then results from a recent test flight are discussed. This flight demonstrated the successful operation of the deployment mechanism and telemetry systems, provided some preliminary plasma measurements in a simple mid-latitude environment, and revealed several design issues.
The study shows that the all-nuclear spacecraft can have a substantial weight advantage over a hybrid (nuclear/solar) or all-solar spacecraft, owing to a further reduction in power requirement, and to the elimination of such equipment as the sensor gimbal and rotating joint assemblies. Because the need for a sun-oriented section is eliminated, the all-nuclear spacecraft can be designed as a monolithic structure, with the sensor and other payload firmly secured in a fixed position on the structure. This enhances attitude stability while minimizing structural weight and eliminating the need for flexible fluid lines. Sensor motion can be produced, varied, and controlled within the limits specified by the study contractors by moving the entire spacecraft in the prescribed pattern. A simple attitude control system using available hardware suffices to meet all requirements
Majer, J; Chow, J M; Gambetta, J M; Koch, Jens; Johnson, B R; Schreier, J A; Frunzio, L; Schuster, D I; Houck, A A; Wallraff, A; Blais, A; Devoret, M H; Girvin, S M; Schoelkopf, R J
Superconducting circuits are promising candidates for constructing quantum bits (qubits) in a quantum computer; single-qubit operations are now routine, and several examples of two-qubit interactions and gates have been demonstrated. These experiments show that two nearby qubits can be readily coupled with local interactions. Performing gate operations between an arbitrary pair of distant qubits is highly desirable for any quantum computer architecture, but has not yet been demonstrated. An efficient way to achieve this goal is to couple the qubits to a 'quantum bus', which distributes quantum information among the qubits. Here we show the implementation of such a quantum bus, using microwave photons confined in a transmission line cavity, to couple two superconducting qubits on opposite sides of a chip. The interaction is mediated by the exchange of virtual rather than real photons, avoiding cavity-induced loss. Using fast control of the qubits to switch the coupling effectively on and off, we demonstrate coherent transfer of quantum states between the qubits. The cavity is also used to perform multiplexed control and measurement of the qubit states. This approach can be expanded to more than two qubits, and is an attractive architecture for quantum information processing on a chip.
This report summarizes the experience and early results from a fuel cell bus demonstration funded by the Federal Transit Administra-tion (FTA) under the National Fuel Cell Bus Program (NFCBP). A team led by the Northeast Advanced Vehicle Consortium a...
Marcus, Julius; Hanson, T. David
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
... a school bus! But riding in cars or school buses comes with some responsibility: You need to ride safely. Luckily, it's not hard to do. Keep reading and you'll learn the rules of car and bus safety. Seatbelt Basics Whenever you ride in a car, ...
Villa, Chiara; Hansen, Nikolaj Friis; Hansen, Kamilla Maria
Objectives: to demonstrate the usefulness of 3D reconstructions to better understand the dynamic of a controlled bus bombing. Materials and methods: 3D models of the victims (pigs) were created from post-mortem CT scanning using Mimic software; 3D models of the crime scene (bus) were generated by...
Illinois State Board of Education, Springfield.
This trainee guide contains six units of materials for use by those studying to become school bus drivers in the State of Illinois. Covered in the units are the following topics: school bus driver role and responsibility, passenger control, first aid, driving fundamentals, accidents and emergencies, and detecting hazards. Each unit contains a…
... 32 National Defense 6 2010-07-01 2010-07-01 false Motor bus operation. 935.138 Section 935.138 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE TERRITORIAL AND INSULAR REGULATIONS WAKE ISLAND CODE Motor Vehicle Code § 935.138 Motor bus operation. Each person operating a motor...
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.
Pettauer, T. V.
The real time behavior, error handling and its simplicity makes CAN a preferable bus protocol to interconnect the various modules of a tower telescope. A schematic description of the control bus for the Kanzelhöhe Vakuum Telescope is given.
Kompier, M.A.J.; Di Martino, V.
Although heterogeneous in methodology and content, 32 studies from 13 countries on bus drivers' work and health are similar in their conclusions. Bus-driving–characterized by high demands, low control and low support – can be regarded as a classic example of high-strain occupation, with high risks
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…
The state of Oklahoma recently published a school bus driver manual on transporting handicapped students. Yearly inservice training sessions are recommended to teach school bus drivers communication skills, use of special equipment for physically handicapped students, and preparation for emergencies. (MLF)
Kirk, Albert; Kuhnle, Paul; Sydnor, Richard; Diener, William; Stowers, David
There is a frequent need to measure the frequency stability and phase noise levels of very high performance signal sources that are required for certain spacecraft missions. These measurements need to be done at different locations as the spacecraft subsystems progress through the various stages of development, assembly, test, and integration. Allan Deviation and Phase Noise of high performance sources are generally measured by comparing the unit under test to a reference standard. Five basic requirements are associated with making these kind of measurements: (1) the reference standard performance needs to be equal or better than the unit under test; (2) the measurement system needs to accommodate odd, nonstandard measurement frequencies that can range from 4 MHz to 35 GHz; (3) warm-up frequency drift and aging can corrupt a measurement and must be dealt with; (4) test equipment generated noise must be understood and prevented from limiting the measurements; (5) test equipment noise performance must be verifiable in the field as needed. A portable measurement system that was built by JPL and used in the field is described. The methods of addressing the above requirements are outlined and some measurement noise floor values are given. This test set was recently used to measure state of the art crystal oscillator frequency standards on the TOPEX and MARS OBSERVER spacecraft during several stages of acceptance tests.
Zhao Long; Liu Wufeng; Qiao Weimin; Jing Lan
The EVME bus controller which is a key component of the HIRFL-CSR control system was improved. Besides reconfiguring the embedded Linux, a utility program was developed for data exchange between the controller and the database. The bus controller is based on ARM920T(ARM9) micro processor which is BGA packaged. The bus controller has the universal interface of VGA display, keyboard, and mouse. The backboard interface logic is programmed in an in-system configurable FPGA device. The bus can drive high current up to 64 mA, with the flexibility of the programmable signal definitions. All the improved performance helped the EVME bus controller play a crucial role in HIRFL-CSR control system. (authors)
Full Text Available Bus Ticket Reservation System is an application that can be used to help booking bus tickets and the buyer will get a report via SMS Gateway. The reservation system is made by conducting field studies in Arjosari Bus Station Malang. This system uses SMS Gateway to send the report to the buyer after booking bus tickets online. SMS Gateway on this application serves as a liaison which delays sms between External Short Message entitiy (ESME and Short Message Service Center (SMSC and so does in reserve.The reservation system made is developed with the PHP programming language and has a prototype system pattern. System functions were tested using the validation testing, performance testing, and usability testing. The results percentage of responses usability testing is 67.7%. This shows that Ticket Reservation System at Arjosari Bus Station can be used well enough.
Full Text Available Rises in the number of transit buses, bus routes, and overall traffic volume in China’s cities, coupled with interference from other transport modes, such as taxis loading and unloading passengers nearby, have led to increasing traffic delays at bus stops, which is considered one of the factors degrading service levels and traffic operations on urban roadways. This paper studies traffic characteristics at bus stops, investigates variations in delay from different types or designs of bus stops, and analyzes the impact of it on traffic capacity, the purpose of which is to propose a solution to predicting the feasibility of an integrated design of bus stops and taxi stands with the help of mathematical models and based on the objectives of optimal traffic operations and passenger transfer.
Dehoff, Ryan R [ORNL; Holmans, Walter [Planetary Systems Corporation
In this project Planetary Systems Corporation proposed utilizing additive manufacturing (3D printing) to manufacture a titanium spacecraft separation system for commercial and US government customers to realize a 90% reduction in the cost and energy. These savings were demonstrated via “printing-in” many of the parts and sub-assemblies into one part, thus greatly reducing the labor associated with design, procurement, assembly and calibration of mechanisms. Planetary Systems Corporation redesigned several of the components of the separation system based on additive manufacturing principles including geometric flexibility and the ability to fabricate complex designs, ability to combine multiple parts of an assembly into a single component, and the ability to optimize design for specific mechanical property targets. Shock absorption was specifically targeted and requirements were established to attenuate damage to the Lightband system from shock of initiation. Planetary Systems Corporation redesigned components based on these requirements and sent the designs to Oak Ridge National Laboratory to be printed. ORNL printed the parts using the Arcam electron beam melting technology based on the desire for the parts to be fabricated from Ti-6Al-4V based on the weight and mechanical performance of the material. A second set of components was fabricated from stainless steel material on the Renishaw laser powder bed technology due to the improved geometric accuracy, surface finish, and wear resistance of the material. Planetary Systems Corporation evaluated these components and determined that 3D printing is potentially a viable method for achieving significant cost and savings metrics.
Kordon, Mark; Hanks, David; Gladden, Roy; Wood, Eric
Multi-Mission Telecom Analysis Tool (MMTAT) is a C-language computer program for analyzing proposed spacecraft telecommunication systems. MMTAT utilizes parameterized input and computational models that can be run on standard desktop computers to perform fast and accurate analyses of telecommunication links. MMTAT is easy to use and can easily be integrated with other software applications and run as part of almost any computational simulation. It is distributed as either a stand-alone application program with a graphical user interface or a linkable library with a well-defined set of application programming interface (API) calls. As a stand-alone program, MMTAT provides both textual and graphical output. The graphs make it possible to understand, quickly and easily, how telecommunication performance varies with variations in input parameters. A delimited text file that can be read by any spreadsheet program is generated at the end of each run. The API in the linkable-library form of MMTAT enables the user to control simulation software and to change parameters during a simulation run. Results can be retrieved either at the end of a run or by use of a function call at any time step.
Mcmartin, W. P.; Gambhir, S. S.
A V-Slit sun sensor is body-mounted on a spin-stabilized spacecraft. During injection from a parking or transfer orbit to some final orbit, the spacecraft may not be dynamically balanced. This may result in wobble about the spacecraft spin axis as the spin axis may not be aligned with the spacecraft's axis of symmetry. While the widely used models in Spacecraft Attitude Determination and Control, edited by Wertz, correct for separation, elevation, and azimuthal mounting biases, spacecraft wobble is not taken into consideration. A geometric approach is used to develop a method for measurement of the sun angle which corrects for the magnitude and phase of spacecraft wobble. The algorithm was implemented using a set of standard mathematical routines for spherical geometry on a unit sphere.
Bus pullout bays are being installed increasingly : on Floridas roads as a safety factor and so that : stopped buses do not impede traffic. In Florida, : state law requires car drivers to yield to buses : when a bus needs to reenter the roadway af...
Full Text Available Bus bunching is one of the most serious problems of urban bus systems. Bus bunching increases waiting and travel time of passengers. Many bus systems use schedules to reach equal headways. Compared to the idea of schedules and the target headway introduced later, we propose a new method to improve the efficiency of a bus system and avoid bus bunching by boarding limits. Our solution can be effectively implemented when buses cannot travel as planned because of bad road conditions and dynamic demands at bus stops. Besides, using our method, bus headways reach the state with equal headways dynamically and spontaneously without drivers’ explicit intervention. Moreover, the method can improve the level of the bus service and reduce total travel time of passengers. We verify our method using an ideal bus route and a real bus route, both showing the success of the proposed method.
Adeli, S. Nasir; Lappas, Vaios J.; Wie, Bong
Recently, there has been a renewed interest in Solar Sails as an alternative means of space propulsion. Many different attitude control systems have been designed for Solar Sails taking advantage of the centre-of-mass (CM)/centre-of-pressure (CP) offset while utilising the main sail structure to position the actuators. However, by attaching actuators to the main sail, these systems increase the risks involved in the deployment subsystem. In this paper we propose an attitude control system (ACS) decoupled from the main sail booms and attached to the spacecraft bus. We use ballast masses to change the CM and highly reflective panels to change the CP, achieving 3-axis control. As a result of the decoupled nature of the ACS, scalability and simplicity can be achieved. This is shown through sizing and simulation of the ACS for three different sail sizes, the 5 m Cubesail, 40 m GeoSail and 245 m interstellar heliopause probe (IHP). The scalable bus-based ACS decreases the risks and complexity involved in the design of the sail deployment subsystem and can be employed alongside any available sail deployment mechanisms.
Full Text Available Background: Bus drivers are a special group of professional drivers who are at a very high risk of fatigue. The aim of the study was to examine whether the driver’s subjective assessment of fatigue allows for the determination of its level and identification of its causes. Material and Methods: The study group comprised 45 randomly selected bus drivers (mean age – 43.7±7.9 years, period of employment as drivers – 14.7±8.6 years. Examinations were performed in all subjects four times – before and after work on the “easy” route (outside the city center, small traffic intensity and before and after work on the “difficult” route (city center, heavy traffic. The fatigue test questionnaire, based on the list of symptoms of fatigue prepared by the Japan Research Committee of Fatigue, was used in the study. Results: The rating of fatigue after the work was significantly higher than that before the work. The profile of fatigue after work was not influenced by the type of route, but the assessment of most symptoms of fatigue reached a higher level after the “difficult” routes and the differences were statistically significant for 7 symptoms. Only the ratings of leg fatigue, feeling of heaviness, and the necessity to squint eyes and gaze with effort reached the higher levels after driving the “easy” routes. It has been found that the level of fatigue was significantly correlated with the job characteristics (driving time, the length of the route, number of stops, etc. and with the abundance of food ingested and type of beverage (coffee vs. others drunk prior to driving. Conclusions: The questionnaire used in our study to assess the subjective feeling of fatigue has proved to be a sensitive and useful tool for indicating the level and causes of fatigue. The relationship between the symptoms of fatigue and the characteristics of job and lifestyle shows that actions must be taken by both the employers and employees to prevent fatigue
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
Pomeranz, Jennifer L
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.
Williamson, Mark; Wiedmeyer, Stanley G; Willit, James L; Barnes, Laurel A; Blaskovitz, Robert J
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.
Norhisham, S.; Ismail, A.; Sidek, L. M.; Borhan, M. N.; Zaini, N.; Yen, A. T. G.
The Transit Capacity and Quality of Service Manual (TCQSM) was chosen based on the review with four manuals and guidelines for the method will be applied. Six (6) attributes, namely Hours of Service, Passenger Load, Transit Auto Travel Time, Service Frequency, Punctuality Performance and Service Coverage were chosen for evaluation.. A total of three (3) operators with seven (7) routes were identified in Kajang. Based on the final results, the Quality of Service (QOS) findings was rated as D, which was regarded as minimum or satisfactory. Most stakeholders’ recommendations were: for the operators to provide information on bus scheduling and have accurate information for the passengers. It was suggested that in future this study can be extended to all routes and could be repeated after the opening of the Mass Rapid Transit (MRT) stations in Kajang, so as to provide a comparison and better evaluation of the public buses in Kajang.
FASTBUS is a new laboratory standard data bus intended for use in experimental data acquisition and control. The development of FASTBUS began with a feasibility study in 1976, and is presently at the development prototyping stage. The principal aims of the standard are to provide a factor of ten or more improvement in speed of data transfers over present systems, as well as to provide an architecture for systems containing multiple processors. Developmental prototypes now in progress include crates, backplanes, cooling devices, power supplies, test and diagnostic modules, and user modules. A sizeable software development effort is also underway. Several experiments have made commitments to use FASTBUS. A review of current work and potential applications is given. 10 figures
Yen Bin, Teo; Azlis-Sani, Jalil; Nur Annuar Mohd Yunos, Muhammad; Ismail, S. M. Sabri S. M.; Tajedi, Noor Aqilah Ahmad
Public transportation acts as social mobility and caters the daily needs of the society for passengers to travel from one place to another. This is true for a country like Malaysia where international trade has been growing significantly over the past few decades. Task analysis assessment was conducted with the consideration of cognitive ergonomic view towards problem related to human factors. Conducting research regarding the task analysis on bus traffic controllers had allowed a better understanding regarding the nature of work and the overall monitoring activities of the bus services. This paper served to study the task analysis assessment on intrastate bus traffic controllers and the objectives of this study include to conduct task analysis assessment on the bus traffic controllers. Task analysis assessment for the bus traffic controllers was developed via Hierarchical Task Analysis (HTA). There are a total of five subsidiary tasks on level one and only two were able to be further broken down in level two. Development of HTA allowed a better understanding regarding the work and this could further ease the evaluation of the tasks conducted by the bus traffic controllers. Thus, human error could be reduced for the safety of all passengers and increase the overall efficiency of the system. Besides, it could assist in improving the operation of the bus traffic controllers by modelling or synthesizing the existing tasks if necessary.
Oungrinis, Konstantinos-Alketas; Liapi, Marianthi; Kelesidi, Anna; Gargalis, Leonidas; Telo, Marinela; Ntzoufras, Sotiris; Paschidi, Mariana
The paper presents the development of an on-going research project that focuses on a human-centered design approach to habitable spacecraft modules. It focuses on the technical requirements and proposes approaches on how to achieve a spatial arrangement of the interior that addresses sufficiently the functional, physiological and psychosocial needs of the people living and working in such confined spaces that entail long-term environmental threats to human health and performance. Since the research perspective examines the issue from a qualitative point of view, it is based on establishing specific relationships between the built environment and its users, targeting people's bodily and psychological comfort as a measure toward a successful mission. This research has two basic branches, one examining the context of the system's operation and behavior and the other in the direction of identifying, experimenting and formulating the environment that successfully performs according to the desired context. The latter aspect is researched upon the construction of a scaled-model on which we run series of tests to identify the materiality, the geometry and the electronic infrastructure required. Guided by the principles of sensponsive architecture, the ISM research project explores the application of the necessary spatial arrangement and behavior for a user-centered, functional interior where the appropriate intelligent systems are based upon the existing mechanical and chemical support ones featured on space today, and especially on the ISS. The problem is set according to the characteristics presented at the Mars500 project, regarding the living quarters of six crew-members, along with their hygiene, leisure and eating areas. Transformable design techniques introduce spatial economy, adjustable zoning and increased efficiency within the interior, securing at the same time precise spatial orientation and character at any given time. The sensponsive configuration is
Bennett, Norman R; Burns, Kevin; Katz, Russell; Kirschenbaum, Jon; Mason, Gary; Shehata, Shawky
The Gravity Probe B spacecraft, developed, integrated, and tested by Lockheed Missiles and Space Company and later Lockheed Martin Corporation, consisted of structures, mechanisms, command and data handling, attitude and translation control, electrical power, thermal control, flight software, and communications. When integrated with the payload elements, the integrated system became the space vehicle. Key requirements shaping the design of the spacecraft were: (1) the tight mission timeline (17 months, 9 days of on-orbit operation), (2) precise attitude and translational control, (3) thermal protection of science hardware, (4) minimizing aerodynamic, magnetic, and eddy current effects, and (5) the need to provide a robust, low risk spacecraft. The spacecraft met all mission requirements, as demonstrated by dewar lifetime meeting specification, positive power and thermal margins, precision attitude control and drag-free performance, reliable communications, and the collection of more than 97% of the available science data. (paper)
National Aeronautics and Space Administration — This SBIR Phase I project will develop the Spacecraft Power Monitor (SPM) which will use non-intrusive electrical monitoring (NEMO). NEMO transforms the power...
National Aeronautics and Space Administration — This project lays the groundwork for the future development of a spacecraft on a chip implementation (SCOC), which would combine the electronics for multiple...
National Aeronautics and Space Administration — We propose to design, build and test an optical extinction monitor for the detection of spacecraft cabin particulates. This monitor will be sensitive to particle...
Shahid, Kamran; Kumar, Krishna Dev
In this paper the use of solar radiation pressure for spacecraft formation reconfiguration at the L2 Sun-Earth/Moon collinear libration point is presented. The system consisting of a leader and three follower spacecraft is considered. The leader spacecraft is assumed to be in a fixed halo trajectory and the follower spacecraft position relative to the leader satellite is controlled using two angles and area; these are varied based on a variable structure model reference adaptive control technique to achieve the desired formation reconfiguration. This approach ensures that all follower spacecraft complete the required maneuver in the same time. An intertially fixed circular trajectory, which is suitable for interferometer missions, is used in this paper. The stability of the proposed controller is established using Lyapunov theory. The performance of the proposed controller is tested through numerical simulation of the governing nonlinear equations of motion and is applied for formation initialization, resizing, retargeting, and rotation. The numerical results demonstrate the effectiveness of the proposed control technique for spacecraft formation reconfiguration using solar radiation pressure at the L2 libration point. Furthermore, control inputs on the order of 15 degrees and 2 m2 for area change are sufficient to execute the maneuvers.
Characterization and performance testing of a prototype DWPF Melter No.2 Dome Heater Bus Bar are described. The prototype bus bar was designed to address the design features of the existing system which may have contributed to water leaks on Melter No.1. Performance testing of the prototype revealed significant improvement over the existing design in reduction of both bus bar and heater connection maximum temperature, while characterization revealed a few minor design and manufacturing flaws in the bar. The prototype is recommended as an improvement over the existing design. Recommendations are also made in the area of quality control to ensure that critical design requirements are met
Full Text Available Article concerns the DALI bus theoretical and practical aspects. The DALI bus is a modern technology developed especially for illumination systems control. Authors are outlining communication basic principles related to the physical layer and going up to more complex data transactions among particular devices. The article main topic is aimed at two device models development based on microcontroller and exploiting that technology. The first of those two devices is a DALI slave unit enabling the light source or multi switch with light indication components control via DALI bus. The second device measures the ambient illumination intensity and it also detects errors in the load.
Full Text Available Fast bus transfer method is the most popular and residual voltage transfer method that is used as a backup in medium voltage buses in general. The use of the advanced technology like open circuit voltage prediction and digital signal processing algorithms can improve the reliability of fast transfer scheme. However, according to the survey results of the recent operation records in nuclear power plants, there were many instances where the fast transfer scheme has failed. To assure bus transfer in any conditions and circumstances, uninterruptible bus transfer scheme utilizing the state of the art medium voltage UPS is discussed and elaborated.
Full Text Available In this paper a fast system voltage stability index (FSVSI has been proposed to assess overall system voltage stability of a multi-bus power system at a particular operating point using the concept of two bus network equivalent. A universal direct voltage stability index has also been explored to assess local (DVSI as well as overall system voltage stability (DSVSI. An index called system transmission quality factor (STQF has been developed to assess the power transmission quality of the overall system in the context of voltage stability. Two FACTS controllers, TCSC and STATCOM have also been incorporated in the present study to observe their effectiveness to ensure voltage stabilty. STATCOM has been found to be superior in order to improve voltage stability of power system as compared to TCSC. The developed concept has been validated using practical India Easten Grid (WBSEB system and it has a high potential of on-line application.
Dheer, D.K.; Doolla, S.; Bandyopadhyay, S.
loss and stability margin is further investigated by identifying the Pareto fronts for modified IEEE 13 bus, IEEE 33 and practical 22-bus radial distribution network with application of Reference point based Non-dominated Sorting Genetic Algorithm (R-NSGA). Results were validated by time domain......For a utility-connected system, issues related to small signal stability with Distributed Generators (DGs) are insignificant due to the presence of a very strong grid. Optimally placed sources in utility connected microgrid system may not be optimal/stable in islanded condition. Among others issues......, small signal stability margin is on the fore. The present research studied the effect of location of droop-controlled DGs on small signal stability margin and network loss on a modified IEEE 13 bus system, an IEEE 33-bus distribution system and a practical 22-bus radial distribution network. A complete...
... school bus operators must be submitted by the applicant to the Administrator together with the transcript... 49 Transportation 7 2010-10-01 2010-10-01 false Comments by private school bus operators. 605.18... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION SCHOOL BUS OPERATIONS School Bus Agreements § 605.18 Comments by...
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…
... applicant: (i) Held a valid CDL with a passenger vehicle endorsement to operate a school bus representative... 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...
...-the-road bus'' is defined in 49 CFR 37.3 as a bus characterized by an elevated passenger deck located... DEPARTMENT OF TRANSPORTATION Federal Transit Administration Over-the-Road Bus Accessibility... Administration (FTA) announces the availability of funds in Fiscal Year (FY) 2012 for the Over-the-Road Bus...
.... This interface control document (ICD) was written to provide a single document that designers of CAIS bus controllers and data acquisition units could reference to ensure interoperability on the CAIS bus. This ICD establishes the requirements for digital command/response, time division multiplexing techniques for a single CAIS bus. It encompasses the physical, electrical, and protocol aspects of the CAIS bus.
Yamada, Yasuyuki; Mizuno, Motoki; Sugiura, Miyuki; Tanaka, Sumio; Mizuno, Yuki; Yanagiya, Toshio; Hirosawa, Masataka
The purpose of this study was to clarify the psychological factors of bus drivers' instability that were related to bus passengers' accidents according to the hypothesis model based on the stress concept of Lazarus and Folkman (1984). This research was carried out in 2006. Participants of the study were 39 Japanese male bus drivers. Their average age was 40.2 (SD: 11.1). The average duration of employment was 4.5 (SD:6.1) years. A questionnaire was used that was composed of items concerning the frequency of bus passengers' accidents, performance of safe driving, job stressors, stress reaction and recognition from others. Based on the results, a model assuming that stress reaction caused by job stressors disturbed the bus driver's safe driving and was associated with passengers' accidents in the bus was verified to some degree. Especially, melancholy and tired feeling toward passengers showed a strong relation to the passengers' accidents in the bus. This suggested much room for intervention. Moreover, the recognition from others of their job was confirmed to act as a control factor of the stress reaction.
This paper considers the problem of optimal controlling of a programmed motion of a rigid spacecraft. Given a cost of the spacecraft as a quadratic function of state and control variables we seek for optimal control laws as functions of the state variables and the angle of programmed rotation that minimize this cost and asymptotically stabilize the required programmed motion. The stabilizing properties of the proposed controllers are proved using the optimal Liapunov techniques. Numerical simulation study is presented
Six dynamic experiments were performed in earth orbit utilizing the RAE spacecraft in order to test the accuracy of the mathematical model of RAE dynamics. The spacecraft consisted of four flexible antenna booms, mounted on a rigid cylindrical spacecraft hub at center, for measuring radio emissions from extraterrestrial sources. Attitude control of the gravity stabilized spacecraft was tested by using damper clamping, single lower leading boom operations, and double lower boom operations. Results and conclusions of the in-orbit dynamic experiments proved the accuracy of the analytic techniques used to model RAE dynamical behavior.
Eke, Fidelis O.
This paper discusses the design and testing of remedial measures that can be taken to achieve reasonable nutation damping of the Galileo spacecraft in the event of failure of its boom damper in flight. One scheme exploits the effects of payload motion on the nutational stability of a spinning spacecraft. This scheme demands that the spacecraft motion compensation algorithm be enabled with the scan platform bore sight pointed in a well chosen direction to produce rapid damping of spacecraft nutation. A second method suggested for nutation damping is a thruster-based open loop control algorithm, utilizing a pair of thrusters as actuators.
Bajpayee Jaya; Durham, Darcie; Ichkawich, Thomas
The Glory program is an Earth and Solar science mission designed to broaden science community knowledge of the environment. The causes and effects of global warming have become a concern in recent years and Glory aims to contribute to the knowledge base of the science community. Glory is designed for two functions: one is solar viewing to monitor the total solar irradiance and the other is observing the Earth s atmosphere for aerosol composition. The former is done with an active cavity radiometer, while the latter is accomplished with an aerosol polarimeter sensor to discern atmospheric particles. The Glory program is managed by NASA Goddard Space Flight Center (GSFC) with Orbital Sciences in Dulles, VA as the prime contractor for the spacecraft bus, mission operations, and ground system. This paper will describe some of the more unique features of the Glory program including the integration and testing of the satellite and instruments as well as the science data processing. The spacecraft integration and test approach requires extensive analysis and additional planning to ensure existing components are successfully functioning with the new Glory components. The science mission data analysis requires development of mission unique processing systems and algorithms. Science data analysis and distribution will utilize our national assets at the Goddard Institute for Space Studies (GISS) and the University of Colorado's Laboratory for Atmospheric and Space Physics (LASP). The Satellite was originally designed and built for the Vegetation Canopy Lidar (VCL) mission, which was terminated in the middle of integration and testing due to payload development issues. The bus was then placed in secure storage in 2001 and removed from an environmentally controlled container in late 2003 to be refurbished to meet the Glory program requirements. Functional testing of all the components was done as a system at the start of the program, very different from a traditional program
In August 1983, the Orange-Seminole-Osceola Transit Authority (OSOTA) initiated six express bus routes in the southwest corridor of Orlando (known collectively as the Southwest Direct) as an UMTA-funded demonstration project. While one objective of t...
...) providing a power bus voltage between 31 and 51.5 VDC. This paper summarizes the newly attained qualification status of the MR 512 arcjet system demonstrating the flexibility of the current design...
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.
Prepared by the Federal Transit Administration (FTA) Office of Research, Demonstration, and Innovation (TRI), this report summarizes the accomplishments of fuel-cell-transit-bus-related research and demonstrations projects supported by FTA through 20...
The increase in transit bus ridership nationally during the past ten years, along with the : proliferation of personal electronic control and communication gadgets is causing more : distractions for the drivers. Earlier research studies have found dr...
Mohammad Hadi Almasi
Full Text Available 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.
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)
Davidsen, Rasmus Schmidt; Tang, Peter Torben; Mizushima, Io
We present the combination of black silicon texturing and blackened bus-bar strings as a potential method for obtaining all-black solar panels, while using conventional, front-contacted solar cells. Black silicon was realized by maskless reactive ion etching resulting in total, average reflectance...... below 0.5% across a 156x156 mm2 silicon wafer. Four different methods to obtain blackened bus-bar strings were compared with respect to reflectance, and two of these methods (i.e., oxidized copper and etched solder) were used to fabricate functional allblack solar 9-cell panels. The black bus-bars (e.......g., by oxidized copper) have a reflectance below 3% in the entire visible wavelength range. The combination of black silicon cells and blackened bus-bars results in aesthetic, all-black panels based on conventional, front-contacted solar cells without compromising efficiency....
Netterstrøm, Bo; Juel, K
As part of a survey on the work environment of bus drivers, 2045 (83%) of 2465 male bus drivers in the three major cities in Denmark in 1978 answered a postal questionnaire on health and working conditions. In order to evaluate the relative occurrence of peptic ulcer among the bus drivers, a foll...... with PU in a 6 3/4-year period. Job dissatisfaction, stress symptoms and lack of some social network factors tended to increase the risk of hospital discharge with PU....... men in the same age group. The incidence of all manifestations of peptic ulcer disease among bus drivers did not differ from the incidence among Danish men. Of occupational and psycho-social factors, wage dissatisfaction and smoking showed statistically significant association with hospital discharge...
Full Text Available Due to relatively low passenger demand, headways of suburban bus route are usually longer than those of urban bus route. Actually it is also difficult to balance the benefits between passengers and operators, subject to the service standards from the government. Hence the headway of a suburban bus route is usually determined on the empirical experience of transport planners. To cope with this problem, this paper proposes an optimization model for designing the headways of suburban bus routes by minimizing the operating and user costs. The user costs take into account both the waiting time cost and the crowding cost. The feasibility and validity of the proposed model are shown by applying it to the Route 206 in Jiangning district, Nanjing city of China. Weightages of passengers’ cost and operating cost are further discussed, considering different passenger flows. It is found that the headway and objective function are affected by the weightages largely.
Full Text Available This paper defines bus timetables setting problem during each time period divided in terms of passenger flow intensity; it is supposed that passengers evenly arrive and bus runs are set evenly; the problem is to determine bus runs assignment in each time period to minimize the total waiting time of passengers on platforms if the number of the total runs is known. For such a multistage decision problem, this paper designed a dynamic programming algorithm to solve it. Global optimization procedures using dynamic programming are developed. A numerical example about bus runs assignment optimization of a single line is given to demonstrate the efficiency of the proposed methodology, showing that optimizing buses’ departure time using dynamic programming can save computational time and find the global optimal solution.
This annual edition of Large Truck and Bus Crash Facts contains descriptive statistics about fatal, injury, and : property damage only crashes involving large trucks and buses in 2008. Selected crash statistics on passenger : vehicles are also presen...
Tan, C. F.; Tee, B. T.; Law, H. C.; Lim, T. L.
Air flow distribution is one of the important factors that will influence the bus passenger comfort during long haul travel. Poor air flow distribution not only cause discomfort to the bus passenger but also influence their travel mode as well. The main purpose of this study is to investigate the air flow performance of the bus air-conditioning system through CFD simulation approach. A 3D CAD model of air ducts was drawn and hence analysed by using CFD software, namely ANSYS Fluent, to determine the airflow rate for every outlets of the air-conditioning system. The simulated result was then validated with experimental data obtained from prototype model of air duct. Based on the findings, new design concepts is proposed with the aim to meet the industry requirement as well as to improve the bus passenger comfort during long haul travel.
This study explored the feasibility of using movable and reusable boarding and alighting (B&A) pads at bus stops. : Potential design alternatives in terms of materials and structural support for these pads were evaluated. The review : focused on the ...
This document describes the Concept of Operations (ConOps) for the Transit Bus Stop Pedestrian Warning (TSPW) application. The ConOps describes the current state of operations with respect to the integration of connected vehicle technology in transit...
Almasi, Mohammad Hadi; Mirzapour Mounes, Sina; Koting, Suhana; Karim, Mohamed Rehan
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.
National Aeronautics and Space Administration — High speed robust very low power radiation hardened bus interconnects are required to accelerate on-board computations, further improve reconfigurability and upgrade...
Lay Eng Teoh; Hooi Ling Khoo; Siew Yoke Goh; Lai Mun Chong
Globally, transportation sector has emerged as one of the major sources of air pollution. Correspondingly, green mobility (with electric bus) is gaining increasing attention as an essential step to mitigate emission concern. As such, a proper electric bus network design and fleet planning is important especially for bus operator to acquire an adequate number of electric bus, right on time, in order to operate electric bus system viably. Thus, this paper aims to examine the possibility to oper...
Foell, Stefan; Phithakkitnukoon, Santi; Kortuem, Gerd; Veloso, Marco; Bento, Carlos
This paper presents a study of the predictability of bus usage based on massive bus ride data collected from Lisbon, Portugal. An understanding of public bus usage behavior is important for future development of personalized transport information systems that are equipped with proactive capabilities such as predictive travel recommender systems. In this study, we show that there exists a regularity in the bus usage and that daily bus rides can be predicted with a high degree of accuracy. In a...
Guo, Hui; Jiang, Ying
With the feature of multi-master bus access, nondestructive contention-based arbitration and flexible configuration, Controller Area Network (CAN) bus is applied into the control system of Wire Harness Assembly Machine (WHAM). To accomplish desired goal, the specific features of the CAN bus is analyzed by compared with other field buses and the functional performances in the CAN bus system of WHAM is discussed. Then the application layer planning of CAN bus for dynamic priority is presented. ...
Elana M. Chapman; Shirish Bhide; Jennifer Stefanik; Howard Glunt; Andre L. Boehman; Allen Homan; David Klinikowski
The objectives of this research and demonstration program are to convert a campus shuttle bus to operation on dimethyl ether, a potential ultra-clean alternative diesel fuel. To accomplish this objective, this project includes laboratory evaluation of a fuel conversion strategy, as well as, field demonstration of the DME-fueled shuttle bus. Since DME is a fuel with no lubricity (i.e., it does not possess the lubricating quality of diesel fuel), conventional fuel delivery and fuel injection systems are not compatible with dimethylether. Therefore, to operate a diesel engine on DME one must develop a fuel-tolerant injection system, or find a way to provide the necessary lubricity to the DME. In this project, they have chosen the latter strategy in order to achieve the objective with minimal need to modify the engine. The strategy is to blend DME with diesel fuel, to obtain the necessary lubricity to protect the fuel injection system and to achieve low emissions. The bulk of the efforts over the past year were focused on the conversion of the campus shuttle bus. This process, started in August 2001, took until April 2002 to complete. The process culminated in an event to celebrate the launching of the shuttle bus on DME-diesel operation on April 19, 2002. The design of the system on the shuttle bus was patterned after the system developed in the engine laboratory, but also was subjected to a rigorous failure modes effects analysis with help from Dr. James Hansel of Air Products. The result of this FMEA was the addition of layers of redundancy and over-pressure protection to the system on the shuttle bus. The system became operation in February 2002. Preliminary emissions tests and basic operation of the shuttle bus took place at the Pennsylvania Transportation institute's test track facility near the University Park airport. After modification and optimization of the system on the bus, operation on the campus shuttle route began in early June 2002. However, the
Full Text Available In this paper, a method for the extraction of data for a through-hole vertical interconnect access (via on a printed circuit board (PCB is presented. It uses a matrix de-embedding algorithm and two-port theory to extract the elements of an assumed lumped via model. After that the influence of the via on the power-bus impedance and the coupling between the via and the power-bus are described using this model.
Kaparias, I.; Rossetti, C.; Trozzi, V.
The present study investigates the rather under-explored topic of passenger waiting times at public transport facilities. Using data collected from part of London’s bus network by means of physical counts, measurements and observations, and complemented by on-site passenger interviews, the waiting behaviour is analysed for a number of bus stops served by different numbers of lines. The analysis employs a wide range of statistical methods and tools, and concentrates on three aspects: passenger...
Pozniak, Krzysztof T.
This article discusses a method of building an internal, universal and parametric bus. The solution was designed for a variety of FPGA families and popular VHDL compilers. The algorithm of automatic configuration of address space and methods of receiving and sending addressed data are discussed. The basic solution realized in VHDL language in a behavioral form and chosen examples of practical use of the internal bus are presented in detail.
Ruff, Gary A.; Urban, David L.; Fernandez-Pello, A. Carlos
The status is presented of a spacecraft fire safety research project that is under development to reduce the uncertainty and risk in the design of spacecraft fire safety systems for exploration missions. The Spacecraft Fire Safety Demonstration Project is developing three Spacecraft Fire Experime...
Aoki, Takeo; Uetake, Teruo; Shimoda, Masahiro
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.
Netterstrøm, Bo; Juel, K
The occurrence of low back trouble and possible connection with psychosocial conditions among urban bus drivers were studied using a questionnaire and subsequent registration of hospital discharges. 2,045 (83%) full-time male bus drivers in the three largest cities in Denmark answered a questionn......The occurrence of low back trouble and possible connection with psychosocial conditions among urban bus drivers were studied using a questionnaire and subsequent registration of hospital discharges. 2,045 (83%) full-time male bus drivers in the three largest cities in Denmark answered...... a questionnaire in 1978 regarding psychosocial factors and health. The prevalence of frequent low back pain was 57%. In a control group of 195 motormen the prevalence was 40%. Standardized Morbidity Ratio for bus drivers discharged from hospital during the period 1978-1984 with the diagnosis lumbar disc...... herniation was 137 compared to all Danish men. These differences were statistically significant. Of psychosocial factors only "the feeling of being mentally unbalanced" was found to be statistically significantly related to subsequent hospital discharge with a LBT-diagnosis. Long seniority as bus driver...
O'Neal, Elizabeth; Ramirez, Marizen; Hamann, Cara; Young, Tracy; Stahlhut, Mary; Peek-Asa, Corinne
Although prior research has established that school buses are a safe form of transportation, crashes can produce catastrophic consequences. School buses have 2 types of routes: predictable, routine routes that take children to and from school and less predictable, nonroutine routes for school events. No studies have examined school bus crash incidence and characteristics by these route types. School bus crashes were identified from the Iowa Department of Transportation Crash Database from mid-2005 through mid-2010. Crash reports did not identify whether the bus was on a routine or nonroutine route, so a protocol to assign these based on day and time was developed. Bus mileage was provided by the Iowa Department of Education. The school bus crash rate was 2.1 times higher on nonroutine routes than on routine routes (95% CI = 1.8-2.3). Most crashes involved an improper action by the driver of another vehicle. In crashes attributed to improper actions of school buses, failure to yield the right-of-way and disregarding traffic signs were more common on routine routes, while losing control, speeding, reckless, or aggressive driving were more common on nonroutine routes. School bus crashes are more likely to occur on nonroutine routes. © 2014, American School Health Association.
A healthy and efficient public transit system is indispensable to reduce congestion, emissions, energy consumption, and car : dependency in urban areas. The objective of this research is to 1) develop methods to evaluate and visualize bus service rel...
The overall aim of this thesis is to assess the carbon footprint of transport by bus in the Trondheim region. Bus transportation is promoted as a strategy both to combat local pollution problems in urban areas and to mitigate global greenhouse gas emissions from passenger transport. Still, the environmental impacts of bus transport have received fairly limited attention in research. The environmental impacts of bus transport are calculated through life cycle assessment. A model is develo...
Elana M. Chapman; Shirish Bhide; Jennifer Stefanik; Howard Glunt; Andre L. Boehman; Allen Homan; David Klinikowski
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
CERN Housing Service
'Y' buses cover the journey between Val Thoiry in France (shopping centre including'Migros' and other stores) and Blandonnet in Switzerland, where they stop outside the 'Jumbo' shop, now renamed 'Carrefour'. In France, the buses connect up Thoiry, Sergy and St. Genis, then cross the border to stop outside CERN, Meyrin, before continuing towards Geneva along the 'Route de Meyrin', stopping outside the 'La Tour' hospital, then at the terminus Blandonnet. The normal fare on French territory with a slight incursion into Switzerland for this purpose as far as CERN, Meyrin, is 1.20 Euros per single journey (ticket valid for one hour). The same amount is charged for any single journey in Switzerland. For example, the cost of a single journey between St. Genis and the 'La Tour' hospital would be 2.40 Euros. The season ticket ('Abonnement de Travail') opens the right to purchase a ticket valid over any period of seven days which entitles the holder to as many journeys as required between the bus stop nearest to the pl...
Holt, A. C.
Aerobraking concepts are being studied to improve performance and cost effectiveness of propulsion systems for Mars landers and Mars interplanetary spacecraft. Access to megawatt power levels (nuclear power coupled to high-storage inductive or capacitive devices) on a manned Mars interplanetary spacecraft may make feasible electromagnetic braking and lift modulation techniques which were previously impractical. Using pulsed microwave and magnetic field technology, potential plasmadynamic braking and hydromagnetic lift modulation techniques have been identified. Entry corridor modulation to reduce loads and heating, to reduce vertical descent rates, and to expand horizontal and lateral landing ranges are possible benefits. In-depth studies are needed to identify specific design concepts for feasibility assessments. Standing wave/plasma sheath interaction techniques appear to be promising. The techniques may require some tailoring of spacecraft external structures and materials. In addition, rapid response guidance and control systems may require the use of structurally embedded sensors coupled to expert systems or to artificial intelligence systems.
Bjarnø, Jonas Bækby
of the instrument, and affecting operations during agile and complex spacecraft attitude maneuvers. As such, there exists a theoretical foundation for augmenting the high frequency performance of the μASC instrument, by harnessing the complementary nature of optical stellar reference and inertial sensor technology...... over the entire span of frequencies applicable to spacecraft attitude control systems. Completing the first steps from theoretical possibility towards a proven concept constitutes the primary focus of the project, having necessitated extensive research and development within several diverse technical......Spacecraft platform instability constitutes one of the most significant limiting factors in hyperacuity pointing and tracking applications, yet the demand for accurate, timely and reliable attitude information is ever increasing. The PhD research project described within this dissertation has...
Aman, M.M.; Jasmon, G.B.; Bakar, A.H.A.; Mokhlis, H.
Highlights: • A new algorithm is proposed for optimum DG placement and sizing.• I 2 R losses minimization and voltage stability maximization is considered in fitness function.• Bus voltage stability and line stability is considered in voltage stability maximization.• Multi-objective PSO is used to solve the problem.• Proposed method is compared with analytical and grid search algorithm. - Abstract: Distributed Generation (DG) placement on the basis of minimization of losses and maximization of system voltage stability are two different approaches, discussed in research. In the new proposed algorithm, a multi-objective approach is used to combine the both approaches together. Minimization of power losses and maximization of voltage stability due to finding weakest voltage bus as well as due to weakest link in the system are considered in the fitness function. Particle Swarm Optimization (PSO) algorithm is used in this paper to solve the multi-objective problem. This paper will also compare the propose method with existing DG placement methods. From results, the proposed method is found more advantageous than the previous work in terms of voltage profile improvement, maximization of system loadability, reduction in power system losses and maximization of bus and line voltage stability. The results are validated on 12-bus, 30-bus, 33-bus and 69-bus radial distribution networks and also discussed in detailed
Ward, Nicholas J.; Shankwitz, Craig; Gorgestani, Alec; Donath, Max; De Waard, Dick; Boer, Erwin R.
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
Zhou Sheng Jie
Full Text Available A MAC protocol for public bus networks, called Bus MAC protocol, designed to provide high quality Internet service for bus passengers. The paper proposed a multi-channel dual clocks three-demission probability random multiple access protocol based on RTS/CTS mechanism, decreasing collisions caused by multiple access from multiple passengers. Use the RTS/CTS mechanism increases the reliability and stability of the system, reducing the collision possibility of the information packets to a certain extent, improves the channel utilization; use the multi-channel mechanism, not only enables the channel load balancing, but also solves the problem of the hidden terminal and exposed terminal. Use the dual clocks mechanism, reducing the system idle time. At last, the different selection of the three-dimensional probabilities can make the system throughput adapt to the network load which could realize the maximum of the system throughput.
Full Text Available This paper presents an improved model for improving headway-based bus route service reliability at bus stops using real-time preventive operation control, taking into account dynamic interaction among random passenger demand, stochastic driving conditions of route segments, and vehicle load capacity constraint. In this model, the real-time information of passenger demand and vehicle operation is involved to predict the imminent unacceptable headway deviation, in the case of which some in-time preventive control strategies are deployed according to the given control rules. As a case study, a single fixed bus route with high-frequency services was simulated and different scenarios of real-time preventive operation control were performed. Headway adherence and average passenger wait time were used to measure bus service reliability. The results show that the improved model is closer to the real bus route service, and using real-time information to predict potential service unreliability and trigger in-time preventive control can reduce bus bunching and avoid big gap.
Ayres, Thomas J.; Bryant, Larry
Deep space missions such as Voyager rely upon a large team of expert analysts who monitor activity in the various engineering subsystems of the spacecraft and plan operations. Senior teammembers generally come from the spacecraft designers, and new analysts receive on-the-job training. Neither of these methods will suffice for the creation of a new team in the middle of a mission, which may be the situation during the Magellan mission. New approaches are recommended, including electronic documentation, explicit cognitive modeling, and coached practice with archived data.
Subhan Rizal Amin
Full Text Available This study aims to analyze the availability and use of public transportation by taking a case study of the Damri bus which has Ngaliyan-Pucanggading route. The availability of public transport is not comparable to the demand for public transportation services so that the problems of transportation emerge. Additionally, the use of public transport becomes an important factor to develop the transportation. The study is conducted by surveying the Damri passengers of B.04 lane and logistic regression is used for the analysis. The method of determining the needs of transportation is issued by Departemen Perhubungan. It is used to calculate and determine whether the public transportation should be added or reduced. Then, the factors used as the independent variables in the analysis are the Damri’s safety, effectiveness, efficiency, service and reliability. The results show that Perum Damri does not need to add more Damri bus for B.04 because the results’ calculation is 0.6. and the factors that significantly influence the use Damri bus is the variable of safety, effectiveness and efficiency. However, the variables of service and reliability do not significantly influence the use of B.04 Damri bus.Penelitian ini bertujuan untuk menganalisis ketersediaan dan penggunaan angkutan sarana angkutan umum penumpang dengan mengambil studi kasus pada bus Damri jalur dengan trayek Ngaliyan-Pucanggading. Ketersediaan sarana angkutan umum yang tersedia tidak sebanding dengan besarnya permintaan akan jasa angkutan umum oleh masyarakat umum sehingga muncul permasalahan transportasi. Di samping itu, penggunaan angkutan umum yang beroperasi menjadi faktor penting dalam upaya pengembangan sarana transportasi. Penelitian ini dilakukan dengan menggunakan metode survey terhadap para penumpang bus Damri jalur B.04 dan dianalisis dengan Regresi Logistik. Metode penentuan kebutuhan armada dikeluarkan oleh Departemen Perhubungan yang digunakan untuk menghitung apakah suatu
Horbury, Tim S.; Osman, Kareem T.
Turbulence is ubiquitous in space plasmas, from the solar wind to supernova remnants, and on scales from the electron gyroradius to interstellar separations. Turbulence is responsible for transporting energy across space and between scales and plays a key role in plasma heating, particle acceleration and thermalisation downstream of shocks. Just as with other plasma processes such as shocks or reconnection, turbulence results in complex, structured and time-varying behaviour which is hard to measure with a single spacecraft. However, turbulence is a particularly hard phenomenon to study because it is usually broadband in nature: it covers many scales simultaneously. One must therefore use techniques to extract information on multiple scales in order to quantify plasma turbulence and its effects. The Cluster orbit takes the spacecraft through turbulent regions with a range of characteristics: the solar wind, magnetosheath, cusp and magnetosphere. In each, the nature of the turbulence (strongly driven or fully evolved; dominated by kinetic effects or largely on fluid scales), as well as characteristics of the medium (thermalised or not; high or low plasma sub- or super-Alfvenic) mean that particular techniques are better suited to the analysis of Cluster data in different locations. In this chapter, we consider a range of methods and how they are best applied to these different regions. Perhaps the most studied turbulent space plasma environment is the solar wind, see Bruno and Carbone ; Goldstein et al.  for recent reviews. This is the case for a number of reasons: it is scientifically important for cosmic ray and solar energetic particle scattering and propagation, for example. However, perhaps the most significant motivations for studying solar wind turbulence are pragmatic: large volumes of high quality measurements are available; the stability of the solar wind on the scales of hours makes it possible to identify statistically stationary intervals to
Kerslake, Thomas W.; Haraburda, Francis M.; Riehl, John P.
The Radiation and Technology Demonstration (RTD) Mission has the primary objective of demonstrating high-power (10 kilowatts) electric thruster technologies in Earth orbit. This paper discusses the conceptual design of the RTD spacecraft photovoltaic (PV) power system and mission performance analyses. These power system studies assessed multiple options for PV arrays, battery technologies and bus voltage levels. To quantify performance attributes of these power system options, a dedicated Fortran code was developed to predict power system performance and estimate system mass. The low-thrust mission trajectory was analyzed and important Earth orbital environments were modeled. Baseline power system design options are recommended on the basis of performance, mass and risk/complexity. Important findings from parametric studies are discussed and the resulting impacts to the spacecraft design and cost.
Mohammad Saied Fallah Niasar
Full Text Available he school bus routing problem (SBRP represents a variant of the well-known vehicle routing problem. The main goal of this study is to pick up students allocated to some bus stops and generate routes, including the selected stops, in order to carry students to school. In this paper, we have proposed a simple but effective metaheuristic approach that employs two features: first, it utilizes large neighborhood structures for a deeper exploration of the search space; second, the proposed heuristic executes an efficient transition between the feasible and infeasible portions of the search space. Exploration of the infeasible area is controlled by a dynamic penalty function to convert the unfeasible solution into a feasible one. Two metaheuristics, called N-ILS (a variant of the Nearest Neighbourhood with Iterated Local Search algorithm and I-ILS (a variant of Insertion with Iterated Local Search algorithm are proposed to solve SBRP. Our experimental procedure is based on the two data sets. The results show that N-ILS is able to obtain better solutions in shorter computing times. Additionally, N-ILS appears to be very competitive in comparison with the best existing metaheuristics suggested for SBRP
Sun, Bo; Dragicevic, Tomislav; Vasquez, Juan Carlos
and flywheel converters, and the two flywheels are able to share the power peak through the voltage vs speed droop control. Furthermore, a reduced small-signal model has been built for the purpose of stability analysis and parameter optimization. Finally, real-time simulation results performed on a reduced......Fast charging stations (FCS) will become an essential part of future transportation systems with an increasing number of electrical vehicles. However, since these FCS plugs have power ratings of up to 100 kW, serious stress caused by large number of FCS could threaten the stability of the main...... power grid. To overcome the possible adverse impacts, this paper applies a dedicated paralleled flywheels energy storage system (ESS) in FCS, to balance the power by the method of ramping the initial power peak. Distributed DC-bus signaling (DBS) method is employed in the power coordination of grid...
Nagatani, Takashi; Naito, Yuichi
We have studied the dynamic behavior of a bus in the shuttle bus transportation with a periodic inflow. A bus schedule is closely related to the dynamics. We present the modified circle map model for the dynamics of the shuttle bus. The motion of the shuttle bus depends on the loading parameter and the inflow period. The shuttle bus displays the periodic, quasi-periodic, and chaotic motions with varying both loading parameter and inflow rate. -- Highlights: → We studied the dynamic behavior of a bus in the shuttle bus transportation. → We presented the modified circle map model for the bus schedule. → We clarified the dependence of the tour time on both loading parameter and inflow period.
Lay Eng Teoh
Full Text Available Globally, transportation sector has emerged as one of the major sources of air pollution. Correspondingly, green mobility (with electric bus is gaining increasing attention as an essential step to mitigate emission concern. As such, a proper electric bus network design and fleet planning is important especially for bus operator to acquire an adequate number of electric bus, right on time, in order to operate electric bus system viably. Thus, this paper aims to examine the possibility to operate electric bus as a replacement for the conventional bus operation (with natural gas buses for the study area in Putrajaya, Malaysia. In order to determine a proper-designed electric bus operating system in terms of electric bus route, service frequency and quantity, the proposed methodology is developed with the aid of a traffic modeling software to cater various scenarios. Based on the existing (conventional traffic and transit system in Putrajaya, the developed electric bus operating model is calibrated accordingly by considering various operational concerns including battery capacity and charging facility. The resultant findings revealed that the developed electric bus operating system in Putrajaya outperforms the conventional bus operation, not only in generating a higher profit margin for the bus operator, but also satisfying the passengers in a better manner (by carrying more passengers per unit of bus with a lower energy consumption.
Sinha, A.K. [I.I.T., Kharagpur (India). Dept. of Electrical Engineering; Hazarika, D. [Assam Engineering College (India)
The paper compares the effectiveness of voltage stability indices in providing information about the proximity of voltage instability of a power system. Three simple voltage stability indices are proposed and their effectiveness is compared with some of the recently proposed indices. The comparison is carried out over a wide range of system operating conditions by changing the load power factor and feeder X/R ratios. Test results for the IEEE 57 bus and IEEE 118 bus system are presented. (author)
Hastrup, R. C.; Cesarone, R. J.; Morabito, D. D.
Recently, NASA's Jet Propulsion Laboratory completed a Mars Exploration Program Architecture Definition Study with strong international participation. The recommendations of this study include establishment of a low cost in-situ communications and navigation satellite network to provide enabling and enhancing support for the international exploration of Mars. This would be the first step toward establishing a "virtual presence throughout the solar system" as called for in NASA's Strategic Plan. Response to the proposed comm/nav satellite network has been very favorably received, as reflected by the inclusion of a line item in NASA's budget submittal to Congress, which provides funding for implementation of the network with first launch in the 2003 opportunity. Funding has already been provided for a phase A study being conducted this year. This paper presents the planned implementation of the comm/nav network, which will utilize microsats based on a multi-mission spacecraft bus being designed for launch by the Ariane 5 as a secondary payload. A companion paper at this conference, entitled "The Multi-Purpose Mars Micro-Mission System Design Utilizing Ariane 5 Piggyback Launch", describes the multimission bus design. This paper addresses the application of the multi-mission bus to the comm/nav microsat mission. Following an introduction, which provides the background that has led to the proposed comm/nav network, the paper discusses the projected user needs with emphasis on the various possible robotic missions (landers, rovers, ascent vehicles, balloons, aircraft, etc.) progressing toward eventual piloted missions. Next, the paper describes the concept for an evolving network of comm/nav microsats and the expected capability to satisfy the user needs. Results of communications and navigation performance analysis are summarized for attractive satellite constellation configurations. The important comm/nav microsat functional requirements on the multi
Selvakumar, M.; Abishek Reddy, M.; Sathish, V.; Venkatesh, R.
A modal shift occurs when one mode of transport has a comparative advantage in a similar market over another. The present work concerns with the development of modal shift model for urban travel in Chennai, India. The modal shift model was calibrated using binary logit technique and validated using hold-out sample method. The validated model was used to predict the probability of shift in selected corridor. The recent introduction of metro rail in Chennai has lead to an increasing competition among public transport modes. To study the influence of metro on bus transport, a Stated Preference (SP) survey was conducted among express bus travellers. Using the SP survey data, a modal shift model was calibrated to estimate the plausible shift from bus to metro. Results indicate that variables like fare-difference, age, and income play an important role in the shift behaviour. When metro fare increases with respect to express bus fare, bus passengers are less willing to use metro and vice-versa.
Full Text Available This paper proposes a model for estimating car delays at bus stops under mixed traffic using probability theory and queuing theory. The roadway is divided to serve motorized and nonmotorized traffic streams. Bus stops are located on the nonmotorized lanes. When buses dwell at the stop, they block the bicycles. Thus, two conflict points between car stream and other traffic stream are identified. The first conflict point occurs as bicycles merge to the motorized lane to avoid waiting behind the stopping buses. The second occurs as buses merge back to the motorized lane. The average car delay is estimated as the sum of the average delay at these two conflict points and the delay resulting from following the slower bicycles that merged into the motorized lane. Data are collected to calibrate and validate the developed model from one site in Beijing. The sensitivity of car delay to various operation conditions is examined. The results show that both bus stream and bicycle stream have significant effects on car delay. At bus volumes above 200 vehicles per hour, the curbside stop design is not appropriate because of the long car delays. It can be replaced by the bus bay design.
Pandangwati, S. T.; Milyanab, N. A.
Public transport is the most effective mode of transport in the era of climate change and oil depletion. It can address climate change issues by reducing urban greenhouse gas emission and oil consumption while at the same time improving mobility. However, many public transport networks are not effective and instead create high operating costs with low frequencies and occupancy. Melbourne is one example of a metropolitan area that faces this problem. Even though the city has well-integrated train and tram networks, Melbourne’s bus network still needs to be improved. This study used network planning approach to redesign the bus network in the City of Glen Eira, a Local Government Area (LGA) in the southeastern part of Metropolitan Melbourne. The study area is the area between Gardenvale North and Oakleigh Station, as well as between Caulfield and Patterson Stations. This area needs network improvement mainly because of the meandering bus routes that run within it. This study aims to provide recommendations for improving the performance of bus services by reducing meandering routes, improving transfer point design and implementing coordinated timetables. The recommendations were formulated based on a ‘ready-made’ concept to increase bus occupancy. This approach can be implemented in other cities with similar problems and characteristics including those in Indonesia.
Kabganian, Mansour; Kouhi, Hamed; Shahravi, Morteza; Fani Saberi, Farhad
The thrust vector control (TVC) scheme is a powerful method in spacecraft attitude control. Since the control of a small spacecraft is being studied here, a solid rocket motor (SRM) should be used instead of a liquid propellant motor. Among the TVC methods, gimbaled-TVC as an efficient method is employed in this paper. The spacecraft structure is composed of a body and a gimbaled-SRM where common attitude control systems such as reaction control system (RCS) and spin-stabilization are not presented. A nonlinear two-body model is considered for the characterization of the gimbaled-thruster spacecraft where, the only control input is provided by a gimbal actuator. The attitude of the spacecraft is affected by a large exogenous disturbance torque which is generated by a thrust vector misalignment from the center of mass (C.M). A linear control law is designed to stabilize the spacecraft attitude while rejecting the mentioned disturbance torque. A semi-analytical formulation of the region of attraction (RoA) is developed to ensure the local stability and fast convergence of the nonlinear closed-loop system. Simulation results of the 3D maneuvers are included to show the applicability of this method for use in a small spacecraft.
Siddhartha K. RASTOGI
Full Text Available Indore is a typical tier-2 town in the central province of India, fast becoming a regional commercial hub in an economically booming state. The city has a population of over 2 million with no significant public transport. Among the multiple options available, the city started implementing a dedicated corridor based Bus Rapid Transport System (BRTS. The project was jointly mooted by the central, state, and city authorities. However, the system encountered a range of problems, including conflicts and pulls between multiple implementing agencies, delays in delivery of hardware and constructions, land acquisition and compensation, vested interests, public interest litigations, and court orders. The paper analyses the BRTS, introduced in Indore in the midst of 2013, from multiple party perspectives with an underlying search for public policy and public management insights. The broad results indicate feasibility and desirability of the project; however, real problems emerge in public and public perception management.
Feasibility and cost benefits of nuclear-powered standardized spacecraft are investigated. The study indicates that two shuttle-launched nuclear-powered spacecraft should be able to serve the majority of unmanned NASA missions anticipated for the 1980's. The standard spacecraft include structure, thermal control, power, attitude control, some propulsion capability and tracking, telemetry, and command subsystems. One spacecraft design, powered by the radioisotope thermoelectric generator, can serve missions requiring up to 450 watts. The other spacecraft design, powered by similar nuclear heat sources in a Brayton-cycle generator, can serve missions requiring up to 21000 watts. Design concepts and trade-offs are discussed. The conceptual designs selected are presented and successfully tested against a variety of missions. The thermal design is such that both spacecraft are capable of operating in any earth orbit and any orientation without modification. Three-axis stabilization is included. Several spacecraft can be stacked in the shuttle payload compartment for multi-mission launches. A reactor-powered thermoelectric generator system, operating at an electric power level of 5000 watts, is briefly studied for applicability to two test missions of divers requirements. A cost analysis indicates that use of the two standardized spacecraft offers sizable savings in comparison with specially designed solar-powered spacecraft. There is a duplicate copy.
Eudy, Leslie [National Renewable Energy Lab. (NREL), Golden, CO (United States); Post, Matthew [National Renewable Energy Lab. (NREL), Golden, CO (United States)
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.
Full Text Available Unsuitable locations of bus stops which provide feeder transportation connecting subways near urban intersections usually lead to the low efficiency of public transport and level of passenger service. A multiobjective optimization model to distribute such stop locations is proposed to attain the shortest total walk distance of passengers and minimum delay time of cars through intersections and travel time of buses. The Pareto frontier and optimal solutions for the proposed model are given by the distance-based and enumerative methods. The Xizhimen bus stop is selected to implement case studies for verifying the validity of the proposed model. The analysis of sensitivity on possible solutions is also carried out in the case studies. The results show that the proposed model is capable of optimizing the locations of bus stops connecting subways near intersections and helpful to improve the level of passengers service and operational efficiency of public transportation.
National Aeronautics and Space Administration — For spacecraft design and development teams concerned with cost and schedule, the Quick Spacecraft Thermal Analysis Tool (QuickSTAT) is an innovative software suite...
National Aeronautics and Space Administration — The I-Logix team proposes development of the Service Oriented Spacecraft Modeling Environment (SOSME) to allow faster and more effective spacecraft system design...
Full Text Available Fractionated spacecrafts are of particular interest for pointing-intensive missions because of their ability to decouple physically the satellite bus and some imaging payloads, which possess a lesser lifecycle cost than a comparable monolithic spacecraft. Considering the probabilistic uncertainties during the mission lifecycle, the cost assessment or architecture optimization is essentially a stochastic problem. Thus, this research seeks to quantitatively assess different spacecraft architecture strategies for remote-sensing missions. A dynamical lifecycle simulation and parametric models are developed to evaluate the lifecycle costs, while the mass, propellant usage, and some other constraints on spacecraft are assessed using nonparametric, physics-based computer models. Compared with the traditional Monte Carlo simulation to produce uncertain distributions during the lifecycle, the unscented transformation is employed to reduce the computational overhead, just as it does in improving the extended Kalman filter. Furthermore, the genetic algorithm is applied to optimize the fractionated architecture based on the probabilistic value-centric assessments developed in this paper.
Anderson, John D.
Current spacecraft tests of general relativity depend on coherent radio tracking referred to atomic frequency standards at the ground stations. This paper addresses the possibility of improved tests using essentially the current system, but with the added possibility of a space-borne atomic clock. Outside of the obvious measurement of the gravitational frequency shift of the spacecraft clock, a successor to the suborbital flight of a Scout D rocket in 1976 (GP-A Project), other metric tests would benefit most directly by a possible improved sensitivity for the reduced coherent data. For purposes of illustration, two possible missions are discussed. The first is a highly eccentric Earth orbiter, and the second a solar-conjunction experiment to measure the Shapiro time delay using coherent Doppler data instead of the conventional ranging modulation.
Stachnik, R. V.; Arnold, D.; Melroy, P.; Mccormack, E. F.; Gezari, D. Y.
Results of an orbital analysis and performance assessment of SAMSI (Spacecraft Array for Michelson Spatial Interferometry) are presented. The device considered includes two one-meter telescopes in orbits which are identical except for slightly different inclinations; the telescopes achieve separations as large as 10 km and relay starlight to a central station which has a one-meter optical delay line in one interferometer arm. It is shown that a 1000-km altitude, zero mean inclination orbit affords natural scanning of the 10-km baseline with departures from optical pathlength equality which are well within the corrective capacity of the optical delay line. Electric propulsion is completely adequate to provide the required spacecraft motions, principally those needed for repointing. Resolution of 0.00001 arcsec and magnitude limits of 15 to 20 are achievable.
Over the past several decades, a variety of laser diagnostic techniques have been developed and applied to diagnose spacecraft propulsion devices. Laser diagnostics are inherently non-intrusive, and provide the opportunity to probe properties such as temperature, concentration or number density of plume species, and plume velocities in the harsh environments of combustion and plasma discharges. This presentation provides an overview of laser diagnostic capabilities for spacecraft propulsion devices such as small monopropellant thrusters, arcjets, ion engines and Hall thrusters. Particular emphasis is placed on recent developments for time-resolved ion velocity measurements in Hall thruster plumes. Results are presented for one such diagnostic method, a time-synchronized CW-laser induced fluorescence (LIF) technique based on a sample hold scheme. This method is capable of correlating measured fluorescence excitation lineshapes with high frequency current fluctuations in the plasma discharge of a Hall thruster and is tolerant of natural drifting in the current oscillation frequency.
Ricchiuto, D.; Mastromauro, R.A.; Liserre, Marco
DC Microgrids have recently received a lot of attention in the last years due to high penetration of renewable energy sources as well as distributed energy storage systems. In the future DC microgrids could be preferable respect to AC microgrids in terms of redundancy since multi-DC-Bus solutions...... could provide a continuative power supply to the loads. An overview of Multi-DC-Bus solutions is presented in this paper. The performances are compared on the basis of possible DC microgrid configurations, redundancy, different DC voltage levels....
Davidsen, Rasmus Schmidt; Tang, Peter Torben; Mizushima, Io
We present the combination of black silicon texturing and blackened bus-bar strings as a potential method for obtaining all-black solar panels, while using conventional, front-contacted solar cells. Black silicon was realized by mask-less reactive ion etching resulting in total, average reflectance...... below 0.5% across a 156x156 mm2 silicon wafer. Black bus-bars were realized by oxidized copper resulting in reflectance below 3% in the entire visible wavelength range. The combination of these two technologies may result in aesthetic, all-black panels based on conventional, front-contacted solar cells...
Lin Zhirong; Guo Guoping; Tu Tao; Li Haiou; Zou Changling; Ren Xifeng; Guo Guangcan; Chen Junxue; Lu Yonghua
We develop an architecture for distributed quantum computation using quantum bus of plasmonic circuits and spin qubits in self-assembled quantum dots. Deterministic quantum gates between two distant spin qubits can be reached by using an adiabatic approach in which quantum dots couple with highly detuned plasmon modes in a metallic nanoring. Plasmonic quantum bus offers a robust and scalable platform for quantum optics experiments and the development of on-chip quantum networks composed of various quantum nodes, such as quantum dots, molecules, and nanoparticles.
The remote temperature monitoring system based on the Controller Area Network (CAN) bus is designed to collect the multi-node remote temperature. By using the STM32F103 as main controller and multiple DS18B20s as temperature sensors, the system achieves a master-slave node data acquisition and transmission based on the CAN bus protocol. And making use of the serial port communication technology to communicate with the host computer, the system achieves the function of remote temperature storage, historical data show and the temperature waveform display.
Anenberg, G. L.
An estimate of the antenna noise temperature and the uplink signal-to-noise ratio has been made for Bremsstrahlung radiation emitted by a spacecraft ion beam; a worst-case situation in which the spacecraft antenna is located in the exit plane of the ion beam and directed at varying angles into the ion beam is assumed. Numerical results of the antenna noise temperature versus antenna pointing angle are given for a typical set of ion beam and antenna pattern parameters. The uplink signal-to-noise ratio due to the ion beam noise alone is given in terms of a critical range in AU at which a typical ranging transmission is received with S/N = 0 db. The effects of the ion beam divergence angle and antenna distance on the ion beam are also presented. Results of the study show typical increases in the antenna noise temperature of about 0.2 K and critical ranges of the order of 3-5 AU. An ion engine thus generally introduces an undetectable level of noise into a spacecraft receiver.
The Americans with Disabilities Act (ADA) of 1990 prescribes the minimum requirements for bus stop accessibility by riders with disabilities. Due to limited budgets, transit agencies can only select a limited number of bus stop locations for ADA impr...
The objective of this study was to develop and evaluate a comprehensive pedestrian safety program for elementary (kindergarten through grade 6) school bus riders. Existing materials, crash data and state laws/regulations on school bus pedestrian safe...
The purpose of this research was to track and observe three Florida public transit agencies as they incorporated and integrated computer-based transit bus simulators into their existing bus operator training programs. In addition to the three Florida...
months. I I I 2. It is estimated that a demonstration program would require * I from 15 to 30 months. I 3 . IASP TLCHNOLOGY REQUIREMENTS C.2.4. SPACECRAFT...ready 86 57 IASP TECHNOLOGY REQUIREMENTS I C.6.3. ACTIVE SPACECRAFT CHARGE CONTROL I REQU!4IP, B, A.F. spacecraft must survive in the natural
Full Text Available 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.
Own, Chung-Ming; Lee, Da-Sheng; Wang, Ti-Ho; Wang, De-Jun; Ting, Yu-Lun
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.
Own, Chung-Ming; Lee, Da-Sheng; Wang, Ti-Ho; Wang, De-Jun; Ting, Yu-Lun
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
National Aeronautics and Space Administration — Spacecraft automation has the potential to assist crew members and spacecraft operators in managing spacecraft systems during extended space missions. Automation can...
Sudiro, B. M
In order to meet the safety and security of the public transportation, design specification of construction body bus or bus frame structures should have an appropriate structural strength and comply with standard design including the safety factor and selection of material besides static and dynamic testing of the part of body bus. It is also realized that a bus carrying passengers have to give secure to the passengers also driver.The fact that a technology concerning with metal works indus...
MUHAMMAD WAQAR ASLAM; ZAHARA BATOOL
This research work has evaluated the performance of urban public bus transport service operating in Gujranwala city of Pakistan. The assessment has been made in terms of financial viability, bus condition, operational performance and user perception. Based on the data requirements, various traffic/transport surveys were conducted including Passenger Boarding and Alighting Survey, Bus Count Survey, Bus Inspection Survey, Illegal Operations Survey and Public Transport User Interview Survey in c...
Miles, John; Potter, Stephen
Buses can be a serious source of city centre air pollution. Electric buses deliver zero emissions but, because of the time required to recharge, more buses are needed for a given timetable than diesel counterparts, so making mainstream electric bus operations prohibitively expensive.\\ud \\ud Early 2014 saw the implementation in Milton Keynes of an electric bus service designed to overcome this problem. An entire bus route has been converted to electric operation with inductive charging at bus ...
Bouwmeester, J.; Langer, M; Gill, E.K.A.
This paper provides results and conclusions on a survey on the implementation and reliability aspects of CubeSat bus interfaces, with an emphasis on the data bus and power distribution. It provides recommendations for a future CubeSat bus standard. The survey is based on a literature study and a
Dargan, Thomas J.; Silverstone, Adam H.
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…
... components that would be expected to require replacement during the bus's normal life cycle. Much of the... percent of the bus life should be simulated and servicing, preventive maintenance, and repair actions..., low, and split-friction surfaces. The parking brake should be evaluated with the bus parked facing...
... STANDARDS Federal Motor Vehicle Safety Standards § 571.221 Standard No. 221; School bus body joint strength... 49 Transportation 6 2010-10-01 2010-10-01 false Standard No. 221; School bus body joint strength... the structural collapse of school bus bodies during crashes. S3. Application. This standard applies to...
... 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. S2... 49 Transportation 6 2010-10-01 2010-10-01 false Standard No. 220; School bus rollover protection...
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…
Full Text Available An analytical model for estimation of the bus departure delax from the bus stopping point after passenger loading is presented. The model allows to take into account the traffic density on a particular road section of the transport network, as well as the bus parameters.
... 49 Transportation 6 2010-10-01 2010-10-01 false Standard No. 222; School bus passenger seating and... requirements for school bus passenger seating and restraining barriers. S2. Purpose. The purpose of this... that the minimum number of occupants can be belted. School bus passenger seat means a seat in a school...
... elevated passenger deck located over a baggage compartment. Intercity, fixed-route over-the-road bus... transporting baggage carried by passengers; and makes meaningful connections with scheduled intercity bus... DEPARTMENT OF TRANSPORTATION Federal Transit Administration Over-the-Road Bus Accessibility...
... defined in 49 CFR 37.3 as a bus characterized by an elevated passenger deck located over a baggage... DEPARTMENT OF TRANSPORTATION Federal Transit Administration Over-the-Road Bus Accessibility... availability of funds in Fiscal Year (FY) 2011 for the Over-the-Road Bus (OTRB) Accessibility Program...
... Anchorages, School Bus Passenger Seating and Crash Protection AGENCY: National Highway Traffic Safety... published on October 21, 2008, which upgraded NHTSA's school bus passenger crash protection requirements.... We make clearer the procedure specifying how we will measure the height of school bus passenger torso...
Rannels, Morris W.
This paper is based on a committee report of the last National School Bus Conference on "Minimum Standards for School Buses." Standards for school bus operations are included for (1) administrators, (2) supervisors, (3) school bus drivers, (4) student passengers, and (5) maintenance and service personnel. The report deals also with procedures for…
Zanger, M.; Webster, L.
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.
Hansen, Nikolaj Friis
pig's position in the bus at the time of detonation. 1 of the pigs was rigged as a suicide bomber while the others were individually placed as passengers and bus driver inside the bus alongside dummies. Measurements of the blast force and fast speed video recordings were made during the detonation...
Full Text Available The attitude tracking problem of spacecraft in the presence of unknown disturbance is investigated. By using the adaptive control technique and the Lyapunov stability theory, a chattering-free adaptive sliding mode control law is proposed for the attitude tracking problem of spacecraft with unknown disturbance. Simulation results are employed to demonstrate the effectiveness of the proposed control design technique in this paper.
Kotiev, G. O.; Butarovich, D. O.; Kositsyn, B. B.
At present, the urgent problem is the reduction of energy costs of urban motor transport. The article proposes a method of solving this problem by developing an energy-efficient law governing the movement of an electric bus along a city route. To solve this problem, an algorithm is developed based on the dynamic programming method. The proposed method allows you to take into account the constraints imposed on the phase coordinates, control action, as well as on the time of the route. In the course of solving the problem, the model of rectilinear motion of an electric bus on a horizontal reference surface is considered, taking into account the assumptions that allow it to be adapted for the implementation of the method. For the formation of a control action in the equations of motion dynamics, an algorithm for changing the traction / braking torque on the wheels of an electric bus is considered, depending on the magnitude of the control parameter and the speed of motion. An optimal phase trajectory was obtained on a selected section of the road for the prototype of an electric bus. The article presents the comparison of simulation results obtained with the optimal energy efficient control law with the results obtained by a test driver. The comparison proved feasibility of the energy efficient control law for the automobile city electric transport.
Several performance metrics can be used to assess the reliability of a transit system. These include on-time arrivals, travel-time : adherence, run-time adherence, and customer satisfaction, among others. On-time arrival at bus stops is one of the pe...
Feldhues, Katherine; Epley, Hannah K.
Two 4-H Camp-related bus tours offered new nontraditional professional development (PD) experiences that better align Extension's PD opportunities with the organization's experiential education pedagogy. Creating quality PD opportunities for employees is important because such experiences can affect overall work performance, community connections,…
Laqua, H.; Niedermeyer, H.; Willmann, I.
Wendelstein 7-X is designed as a steady-state experiment to demonstrate the fusion reactor relevance of the advanced stellarator concept. The experiment's control and data acquisition will be performed by a distributed system of computers and programmable logic controllers (PLCs). Data of several systems have to be combined flexibly to control the machine, requiring a data exchange on a millisecond time scale between several connected units. A discharge can last up to half an hour, thus, the connections may vary during a discharge. Hence, it is desired to provide control relevant data, e.g., measurands, set points, interlock signals, cyclically via a bus system. The paper will analyze the special quality of control data streams and deduce the basic requirements for a real-time data bus. An Ethernet is a candidate for the data bus since it is a widely used broad-band bus with a foreseeable potential for development. Because of its nondeterministic arbitration algorithm Ethernet is generally considered not to be suited for hard real-time applications. It is possible to circumvent this disadvantage of Ethernet either by using switching techniques or a software token to obtain a reliable base for hard real-time data transport.
Hlotova, Y.; Cats, O.; Meijer, S.A.
Stress is an immense problem in modern society; approximately half of all occupational illnesses are directly or indirectly related to stress. The work of a bus driver is typically associated with high stress levels that negatively influence individual well-being as well as workforce management. The
Kanekar, Siddhesh; Thakre, Prashant; Rajkumar, E.
The main purpose of this study was to develop the aerodynamic study of a Maharashtra state road transport bus. The rising fuel price and strict government regulations makes the road transport uneconomical now days. With the objective of increasing fuel efficiency and reducing the emission of harmful exhaust gases. It has been proven experimentally that vehicle consumes almost 40% of the available useful engine power to overcome the drag resistance. This provides us a huge scope to study the influence of aerodynamic drag. The initial of the project was to identify the drag coefficient of the existing ordinary type model called “Parivartan” from ANSYS fluent. After preliminary analysis of the existing model corresponding changes are made in such a way that their implementation should be possible at workshop level. The simulation of the air flow over the bus was performed in two steps: design on SolidWorks CAD and ANSYS (FLUENT) is used as a virtual analysis tool to estimate the drag coefficient of the bus. We have used the turbulence models k-ε Realizable having a better approximation of the actual result. Around 28% improvement in the drag coefficient is achieved by CFD driven changes in the bus design. Coefficient of drag is improved by 28% and fuel efficiency increased by 20% by CFD driven changes.
The author states the conservative principles which govern the authorization procedures for nuclear reactor control systems. Using the example of a feedwater supply regulator, employing a digital, bus-oriented control system, he describes how the stigma attached to the word nuclear can be alleviated. (G.T.H.)
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…
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…
The article deals with the system of information collection and transfer from a centralized relay protection and automation system for medium voltage electrical units based on a passive optical bus. The issues of electromagnetic compatibility of technical devices are also considered, and the intensity of electromagnetic ...
National School Resource Network, Washington, DC.
School bus safety depends as much on responsible students as it does on competent drivers. Periodic on-the-job training is necessary to maintain and increase driver skills in handling buses and pupil passenger behavior. Similarly, continuing instruction on safety rules and the need for personal responsibility for those rules is needed to promote…
Leeds, Robin L.
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…
Lazenberry, Dennis; Anderson, Barbara
This report summarizes the deliberations and recommendations of Minnesota's School Bus Safety Advisory Committee (SBSAC). The committee, which operates under the auspices of the Minnesota Department of Public Safety, is charged to study issues affecting the safety of students on school buses, arrive at consensus on ways to improve student safety…
Mokonyama, Mathetha T
Full Text Available This chapter interrogates some empirical data to examine some of the contributory causes of EBS in South Africa, and uses the City of Johannesburg as a case study. The daily travel patterns of car users are analysed within the context of how bus...
Li, Duo; Zhao, Yifei; Bai, Qiang; Zhou, Bei; Ling, Hongbiao
Though public transport vehicles are rarely involved in mass casualty accidents, when they are, the number of injuries and fatalities is usually high due to the high passenger capacity. Of the few studies that have been conducted on bus safety, the majority focused on vehicle safety features, road environmental factors, as well as driver characteristics. Nevertheless, few studies have attempted to investigate the underlying risk factors related to bus occupants. This article presents an investigation aimed at identifying the risk factors affecting injury severity of bus passengers with different movements. Three different passenger movement types including standing, seated, and boarding/alighting were analyzed individually using classification and regression tree (CART) method based on publicly available accident database of Great Britain. According to the results of exploratory analyses, passenger age and vehicle maneuver are associated with passenger injury severity in all 3 types of accidents. Moreover, the variable "skidding and overturning" is associated with injury severity of seated passengers and driver age is correlated with injury severity of standing and boarding/alighting passengers. The CART method shows its ability to identify and easily explain the complicated patterns affecting passenger injury severity. Several countermeasures to reduce bus passenger injury severity are recommended.
... 49 Transportation 5 2010-10-01 2010-10-01 false Identification-bus and driver. 374.317 Section 374... SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION FEDERAL MOTOR CARRIER SAFETY REGULATIONS PASSENGER CARRIER REGULATIONS Adequacy of Intercity Motor Common Carrier Passenger Service § 374.317 Identification...
Seasonal variation is a well-known phenomenon, in many endeavrous and enterprises. Passenger of patronage of road transportation by bus is generally implicated as exhibiting excessive seasonality. The study thus set out to empirically investigate the myth or reality of the thesis that trip generation and trip attraction can ...
In recent years, Bus Rapid Transit (BRT) has generated great interest across the United States. There are more than 20 BRT : systems in existence, and more are in the planning stage (including in Detroit). Within the next few years, BRT will be plann...
In 1991 the City of Phoenix Public Transit System, first in the nation to install magnetic card readers on the electronic fareboxes in its buses, implemented a program known as Bus Card Plus, which billed employers for trips made by employees using e...
Kong, Alberta S.; Sussman, Andrew L.; Negrete, Sylvia; Patterson, Nissa; Mittleman, Rachel; Hough, Richard
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.…
Kalberg, Signe, 1959-
AS-i Tarbus ja kaheksa bussiettevõtte ühinemisel moodustati AS Go Bus, ettevõte plaanib veel mitme bussifirma liitmist. Atko Grupi juhatuse esimehe Margo Tomingase, AS Sebe nõukogu esimehe Hugo Osula arvamus. Lisa: Konkurentsiamet hoiab silma peal
Full Text Available This work proposes a model considering fairness in the problem of crew scheduling for bus drivers (CSP-BD using a hybrid ant-colony optimization (HACO algorithm to solve it. The main contributions of this work are the following: (a a valid approach for cases with a special cost structure and constraints considering the fairness of working time and idle time; (b an improved algorithm incorporating Gamma heuristic function and selecting rules. The relationships of each cost are examined with ten bus lines collected from the Beijing Public Transport Holdings (Group Co., Ltd., one of the largest bus transit companies in the world. It shows that unfair cost is indirectly related to common cost, fixed cost and extra cost and also the unfair cost approaches to common and fixed cost when its coefficient is twice of common cost coefficient. Furthermore, the longest time for the tested bus line with 1108 pieces, 74 blocks is less than 30 minutes. The results indicate that the HACO-based algorithm can be a feasible and efficient optimization technique for CSP-BD, especially with large scale problems.
Full Text Available UM-BUS is a novel dynamically reconfigurable high-speed serial bus for embedded systems. It can achieve fault tolerance by detecting the channel status in real time and reconfigure dynamically at run-time. The bus supports direct interconnections between up to eight master nodes and multiple slave nodes. In order to solve the time synchronization problem among master nodes, this paper proposes a novel time synchronization method, which can meet the requirement of time precision in UM-BUS. In this proposed method, time is firstly broadcasted through time broadcast packets. Then, the transmission delay and time deviations via three handshakes during link self-checking and channel detection can be worked out referring to the IEEE 1588 protocol. Thereby, each node calibrates its own time according to the broadcasted time. The proposed method has been proved to meet the requirement of real-time time synchronization. The experimental results show that the synchronous precision can achieve a bias less than 20 ns.
Shah, Hardik; Gopal, Raj
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…
Kimnach, Greg L.
The Electrical Systems Development Branch of the Power Technology Division at the NASA Lewis Research Center in Cleveland, Ohio is designing a Power Management and Distribution (PMAD) System for the Air Force's Integrated Solar Upper Stage (ISUS) Engine Ground Test Demonstration (EGD). The ISUS program uses solar-thermal propulsion to perform orbit transfers from Low Earth Orbit (LEO) to Geosynchronous Orbit (GEO) and from LEO to Molnya. The ISUS uses the same energy conversion receiver to perform the LEO to High Earth Orbit (HEO) transfer and to generate on-orbit electric power for the payloads. On-orbit power generation is accomplished via two solar concentrators heating a dual-cavity graphite-core which has Thermionic Diodes (TMD's) encircling each cavity. The graphite core and concentrators together are called the Receiver and Concentrator (RAC). The TDM-emitters reach peak temperatures of approximately 2200K, and the TID-collectors are run at approximately 1000K. Because of the high Specific Impulse (I(sup sp)) of solar thermal propulsion relative to chemical propulsion, and because a common bus is used for communications, GN&C, power, etc., a substantial increase in payload weight is possible. This potentially allows for a stepdown in the required launch vehicle size or class for similar payload weight using conventional chemical propulsion and a separate spacecraft bus. The ISUS power system is to provide 1000W(sub e) at 28+/-6V(sub dc) to the payload/spacecraft from a maximum TID generation capability of 1070W(sub e) at 2200K. Producing power with this quality, protecting the spacecraft from electrical faults and accommodating operational constraints of the TID's are the responsibilities of the PMAD system. The design strategy and system options examined along with the proposed designs for the Flight and EGD configurations are discussed herein.
Mass-spring and liquid dampers enable structural vibration control to attenuate single, coupled lateral and torsional vibrations in diverse structures. Out of these, the passively tuned liquid damper (TLD) class is wanted due to its broad applicability, extreme reliability, robustness, long life
André, Michel; Villanova, André
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
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
Roper, Kathryn; Robinson, Ruth; Moorhouse, Ben
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
Granieri, P P; Casali, M; Bottura, L; Siemko, A
Spurred by the question of the maximum allowable energy for the operation of the Large Hadron Collider (LHC), we have progressed in the understanding of the thermo-electric behavior of the 13 kA superconducting bus bars interconnecting its main magnets. A deep insight of the underlying mechanisms is required to ensure the protection of the accelerator against undesired effects of resistive transitions. This is especially important in case of defective interconnections which can jeopardize the operation of the whole LHC. In this paper we present a numerical model of the interconnections between the main dipole and quadrupole magnets, validated against experimental tests of an interconnection sample with a purposely built-in defect. We consider defective interconnections featuring a lack of bonding among the superconducting cables and the copper stabilizer components, such as those that could be present in the machine. We evaluate the critical defect length limiting the maximum allowable current for powering th...
Full Text Available The paper deals with the analysis of demand for bus transport to examine determinants of demand and practices of high school students based on survey of their transport habits in Žilina Region. Transport habits of students are individual and variable in time. This group of passengers is dependent on public passenger transport services because of their travelling to schools. Significant part of demand for public passenger transport is also formed by this this group of passengers. The knowledge of student's transport habits may help in process of adaptation of offering and quality of transport serviceability what may subsequently stabilize demand for public passenger transport.
Full Text Available Distribution systems can form islands when faults occur. Each island represents a subsection with variable boundaries subject to the location of fault(s in the system. A subsection with variable boundaries is referred to as an island in this paper. For operation in autonomous mode, it is imperative to detect the island configurations and stabilize these subsections. This paper presents a novel scheme for the detection of island boundaries and stabilizing the system during autonomous operation. In the first stage, a boundary detection method is proposed to detect the configuration of the island. In the second stage, a dynamic voltage sensitivity factor (DVSF is proposed to assess the dynamic performance of the system. In the third stage, a wide area load shedding program is adopted based on DVSF to shed the load in weak bus-bars and stabilize the system. The proposed scheme is validated and tested on a generic 18-bus system using a combination of EMTDC/PSCAD and MATLAB software’s.
Supangat, Kenny; Eko Soelistio, Yustinus
Traffic Jam has been a daily problem for people in Jakarta which is one of the busiest city in Indonesia up until now. Even though the official government has tried to reduce the impact of traffic issues by developing a new public transportation which takes up a lot of resources and time, it failed to diminish the problem. The actual concern to this problem actually lies in how people move between places in Jakarta where they always using their own vehicle like cars, and motorcycles that fill most of the street in Jakarta. Among much other public transportations that roams the street of Jakarta, Buses is believed to be an efficient transportation that can move many people at once. However, the location of the bus stop is now have moved to the middle of the main road, and its too far for the nearby residence to access to it. This paper proposes an optimal location of optimal bus stops in West Jakarta that is experimentally proven to have a maximal distance of 350 m. The optimal location is estimated by means of mean shift clustering method while the optimal routes are calculated using Ant Colony algorithm. The bus stops locations rate of error is 0.07% with overall route area of 32 km. Based on our experiments, we believe our proposed bus stop plan can be an interesting alternative to reduce traffic congestion in West Jakarta.
deGroot, Wim A.; Arrington, Lynn A.; McElroy, James F.; Mitlitsky, Fred; Weisberg, Andrew H.; Carter, Preston H., II; Myers, Blake; Reed, Brian D.
Electrolysis propulsion has been recognized over the last several decades as a viable option to meet many satellite and spacecraft propulsion requirements. This technology, however, was never used for in-space missions. In the same time frame, water based fuel cells have flown in a number of missions. These systems have many components similar to electrolysis propulsion systems. Recent advances in component technology include: lightweight tankage, water vapor feed electrolysis, fuel cell technology, and thrust chamber materials for propulsion. Taken together, these developments make propulsion and/or power using electrolysis/fuel cell technology very attractive as separate or integrated systems. A water electrolysis propulsion testbed was constructed and tested in a joint NASA/Hamilton Standard/Lawrence Livermore National Laboratories program to demonstrate these technology developments for propulsion. The results from these testbed experiments using a I-N thruster are presented. A concept to integrate a propulsion system and a fuel cell system into a unitized spacecraft propulsion and power system is outlined.
Full Text Available The hybrid subsystem design could be an attractive approach for futurespacecraft to cope with their demands. The idea of combining theconventional Attitude Control System and the Electrical Power System ispresented in this article. The Combined Energy and Attitude ControlSystem (CEACS consisting of a double counter rotating flywheel assemblyis investigated for small satellites in this article. Another hybrid systemincorporating the conventional Attitude Control System into the ThermalControl System forming the Combined Attitude and Thermal ControlSystem (CATCS consisting of a "fluid wheel" and permanent magnets isalso investigated for small satellites herein. The governing equationsdescribing both these novel hybrid subsystems are presented and theironboard architectures are numerically tested. Both the investigated novelhybrid spacecraft subsystems comply with the reference missionrequirements.The hybrid subsystem design could be an attractive approach for futurespacecraft to cope with their demands. The idea of combining theconventional Attitude Control System and the Electrical Power System ispresented in this article. The Combined Energy and Attitude ControlSystem (CEACS consisting of a double counter rotating flywheel assemblyis investigated for small satellites in this article. Another hybrid systemincorporating the conventional Attitude Control System into the ThermalControl System forming the Combined Attitude and Thermal ControlSystem (CATCS consisting of a "fluid wheel" and permanent magnets isalso investigated for small satellites herein. The governing equationsdescribing both these novel hybrid subsystems are presented and theironboard architectures are numerically tested. Both the investigated novelhybrid spacecraft subsystems comply with the reference missionrequirements.
Gordon, Scott; Kern, Dennis L.
NASA-HDBK-7008 Spacecraft Level Dynamic Environments Testing discusses the approaches, benefits, dangers, and recommended practices for spacecraft level dynamic environments testing, including vibration testing. This paper discusses in additional detail the benefits and actual experiences of vibration testing spacecraft for NASA Goddard Space Flight Center (GSFC) and Jet Propulsion Laboratory (JPL) flight projects. JPL and GSFC have both similarities and differences in their spacecraft level vibration test approach: JPL uses a random vibration input and a frequency range usually starting at 5 Hz and extending to as high as 250 Hz. GSFC uses a sine sweep vibration input and a frequency range usually starting at 5 Hz and extending only to the limits of the coupled loads analysis (typically 50 to 60 Hz). However, both JPL and GSFC use force limiting to realistically notch spacecraft resonances and response (acceleration) limiting as necessary to protect spacecraft structure and hardware from exceeding design strength capabilities. Despite GSFC and JPL differences in spacecraft level vibration test approaches, both have uncovered a significant number of spacecraft design and workmanship anomalies in vibration tests. This paper will give an overview of JPL and GSFC spacecraft vibration testing approaches and provide a detailed description of spacecraft anomalies revealed.
Han Linghui; Sun Huijun; Zhu Chengjuan; Jia Bin; Wu Jianjun
There is an explicit and implicit assumption in multimodal traffic equilibrium models, that is, if the equilibrium exists, then it will also occur. The assumption is very idealized; in fact, it may be shown that the quite contrary could happen, because in multimodal traffic network, especially in mixed traffic conditions the interaction among traffic modes is asymmetric and the asymmetric interaction may result in the instability of traffic system. In this paper, to study the stability of multimodal traffic system, we respectively present the travel cost function in mixed traffic conditions and in traffic network with dedicated bus lanes. Based on a day-to-day dynamical model, we study the evolution of daily route choice of travelers in multimodal traffic network using 10000 random initial values for different cases. From the results of simulation, it can be concluded that the asymmetric interaction between the cars and buses in mixed traffic conditions can lead the traffic system to instability when traffic demand is larger. We also study the effect of travelers' perception error on the stability of multimodal traffic network. Although the larger perception error can alleviate the effect of interaction between cars and buses and improve the stability of traffic system in mixed traffic conditions, the traffic system also become instable when the traffic demand is larger than a number. For all cases simulated in this study, with the same parameters, traffic system with dedicated bus lane has better stability for traffic demand than that in mixed traffic conditions. We also find that the network with dedicated bus lane has higher portion of travelers by bus than it of mixed traffic network. So it can be concluded that building dedicated bus lane can improve the stability of traffic system and attract more travelers to choose bus reducing the traffic congestion. (general)
Vittal, Eknath; O'Malley, Mark; Keane, Andrew
This paper examines the small-signal stability impacts of high penetrations of doubly-fed induction generator (DFIG) wind turbines on power systems. It provides a basic overview of small-signal stability concepts and then examines the response of DFIG generation to two local contingency event. Using the New England 39 bus test system, this paper will demonstrate the stability implications of DFIG turbines utilizing terminal voltage control and fixed power factor control in response...
Larsen, R. A.
Designed to assist pupil transportation supervisors, safety instructors, school bus drivers, curriculum writers, teachers, and others who have some type of responsibility for school bus safety, this suggestion-type booklet provides practical tips for educating student school bus riders. The items covered are (1) going to the bus stop; (2) at the…
Blue Sun Enterprises, Inc. is creating a common deep space bus capable of a wide variety of Mars, asteroid, and comet science missions, observational missions in and near GEO, and interplanetary delivery missions. The spacecraft are modular and highly autonomous, featuring a common core and optional expansion for variable-sized science or commercial payloads. Initial spacecraft designs are targeted for Mars atmospheric science, a Phobos sample return mission, geosynchronous reconnaissance, and en-masse delivery of payloads using packetized propulsion modules. By combining design, build, and operations processes for these missions, the cost and effort for creating the bus is shared across a variety of initial missions, reducing overall costs. A CLIpSAT can be delivered to different orbits and still be able to reach interplanetary targets like Mars due to up to 14.5 km/sec of delta-V provided by its high-ISP Xenon ion thruster(s). A 6U version of the spacecraft form fits PPOD-standard deployment systems, with up to 9 km/s of delta-V. A larger 12-U (with the addition of an expansion module) enables higher overall delta-V, and has the ability to jettison the expansion module and return to the Earth-Moon system from Mars orbit with the main spacecraft. CLIpSAT utilizes radiation-hardened electronics and RF equipment, 140+ We of power at earth (60 We at Mars), a compact navigation camera that doubles as a science imager, and communications of 2000 bps from Mars to the DSN via X-band. This bus could form the cornerstone of a large number asteroid survey projects, comet intercept missions, and planetary observation missions. The TugBot architecture uses groups of CLIpSATs attached to payloads lacking innate high-delta-V propulsion. The TugBots use coordinated trajectory following by each individual spacecraft to move the payload to the desired orbit - for example, a defense asset might be moved from GEO to lunar transfer orbit in order to protect and hide it, then returned
Techniques are discussed for controlling the potential of a spacecraft by means of devices which release appropriate charged particles from the spacecraft to the environment. Attention is given to electron emitters, ion emitters, a basic electron emitter arrangement, techniques for sensing electric field or potential, and flight experiments on active potential control. It is recommended to avoid differential charging on spacecraft surfaces because it can severely affect the efficacy of emitters. Discharging the frame of a spacecraft with dielectric surfaces involves the risk of stressing the dielectric material excessively. The spacecraft should, therefore, be provided with grounded conductive surfaces. It is pointed out that particles released by control systems can return to the spacecraft.
Lee, Allan Y.; Wang, Eric K.; Macala, Glenn A.
There have been a number of missions with spacecraft flying by planetary moons with atmospheres; there will be future missions with similar flybys. When a spacecraft such as Cassini flies by a moon with an atmosphere, the spacecraft will experience an atmospheric torque. This torque could be used to determine the density of the atmosphere. This is because the relation between the atmospheric torque vector and the atmosphere density could be established analytically using the mass properties of the spacecraft, known drag coefficient of objects in free-molecular flow, and the spacecraft velocity relative to the moon. The density estimated in this way could be used to check results measured by science instruments. Since the proposed methodology could estimate disturbance torque as small as 0.02 N-m, it could also be used to estimate disturbance torque imparted on the spacecraft during high-altitude flybys.
Krupnikov, K K; Mileev, V N; Novikov, L S; Sinolits, V V
This report presents some examples of a computer simulation of spacecraft interaction with space environment. We analysed a set data on electron and ion fluxes measured in 1991-1994 on geostationary satellite GORIZONT-35. The influence of spacecraft eclipse and device eclipse by solar-cell panel on spacecraft charging was investigated. A simple method was developed for an estimation of spacecraft potentials in LEO. Effects of various particle flux impact and spacecraft orientation are discussed. A computer engineering model for a calculation of space radiation is presented. This model is used as a client/server model with WWW interface, including spacecraft model description and results representation based on the virtual reality markup language.
Krupnikov, K.K.; Makletsov, A.A.; Mileev, V.N.; Novikov, L.S.; Sinolits, V.V.
This report presents some examples of a computer simulation of spacecraft interaction with space environment. We analysed a set data on electron and ion fluxes measured in 1991-1994 on geostationary satellite GORIZONT-35. The influence of spacecraft eclipse and device eclipse by solar-cell panel on spacecraft charging was investigated. A simple method was developed for an estimation of spacecraft potentials in LEO. Effects of various particle flux impact and spacecraft orientation are discussed. A computer engineering model for a calculation of space radiation is presented. This model is used as a client/server model with WWW interface, including spacecraft model description and results representation based on the virtual reality markup language
National Aeronautics and Space Administration — Saber Astronautics proposes spacecraft subsystem control software which can autonomously reconfigure avionics for best performance during various mission conditions....
This paper discusses the Electrical Power Subsystem (EPS) requirements, architecture, design description, performance analysis, and heritage of the components for two spacecraft concepts for the High Energy Solar Physics (HESP) Mission. It summarizes the mission requirements and the spacecraft subsystems and instrument power requirements, and it describes the EPS architecture for both options. A trade study performed on the selection of the solar cells - body mounted versus deployed panels - and the optimum number of panels is also presented. Solar cell manufacturing losses, array manufacturing losses, and the radiation and temperature effects on the GaAs/Ge and Si solar cells were considered part of the trade study and are included in this paper. Solar cell characteristics, cell circuit description, and the solar array area design are presented, as is battery sizing analysis performed based on the power requirements during launch and initial spacecraft operations. This paper discusses Earth occultation periods and the battery power requirements during this period as well as shunt control, battery conditioning, and bus regulation schemes. Design margins, redundancy philosophy, and predicted on-orbit battery and solar cell performance are summarized. Finally, the heritage of the components and technology risk assessment are provided.
Eudy, Leslie [National Renewable Energy Lab. (NREL), Golden, CO (United States); Post, Matthew [National Renewable Energy Lab. (NREL), Golden, CO (United States); Jeffers, Matthew [National Renewable Energy Lab. (NREL), Golden, CO (United States)
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, which was developed as part of the Federal Transit Administration's (FTA) National Fuel Cell Bus Program, was delivered to SunLine in November 2011 and was put in revenue service in mid-December 2011. Two new AFCBs with an upgraded design were delivered in June/July of 2014 and a third new AFCB was delivered in February 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 covers the performance of the AFCBs from July 2015 through December 2016.
Gudmundsson, Henrik; Sørensen, Claus Hedegaard
“Sustainable transport” has become a headline for transport planning and policy making around the world. While there are many different definitions of what Sustainable Transport means, it commonly includes efforts to improve the environmental performance of transport systems, and to promote...... depends on how the bus sector is organised. By organisation we adopt an institutional point of view and consider basic modes of governance. Basic modes of governance include the forms “market”, “hierarchy” and “network” (Powell 1990). So-called New Public Management (NPM) reforms have changed the modes......: Public bus transport in England, exemplified by Greater Manchester. England represents a situation where - compared to continental Europe including Denmark - the NPM reforms have been particularly radical. In no other European country the market forces has achieved a role as dominant as in England...
Kajouke, Lateef A; Perisic, Milun; Ransom, Ray M
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.
Buning, Mary Ellen; Karg, Patricia E
For children with Individualized Education Plans (IEPs), transportation is considered a related service and a part of their education. This paper presents an overview of the current status of wheelchair transportation for students on school buses within the United States. The review includes the school transportation environment for wheelchair-seated students, applicable regulations and voluntary standards, primary safety issues for wheelchair-seated students, and key stakeholders roles in improving wheelchair transportation safety. Future actions to improve wheelchair transportation safety in school transportation are discussed, including the need to improve data collection, mandate payment for and use of RESNA WC19-compliant wheelchairs, improve training for bus operators and attendants, and require specialty certification for school bus operators who transport wheelchair-seated students.
Nanaki, Eva; Koroneos, Christophis; Roset, Jaume
The transportation sector is one of the largest sources of EU’s greenhouse gas emissions. In 2011, transportation represented approximately 25 percent of total EU’s greenhouse gas emissions. Urban mobility accounts for 40% of all CO2 emissions of road transport and up to 70% of other pollutants...... that affect the production of carbon dioxide (CO2) as well as of air pollutants, in 9 major European cities, aiming to provide a comprehensive overview of the actual knowledge on the atmospheric pollution from public transportation systems. CO2 emissions as well as air pollutants, such as CO, HC, PM, NOx...... are calculated for the diesel and CNG bus fleets of the European cities under study. Finally the environmental benefits, in terms of CO2 and CO, HC, PM, NOx emissions reductions, from the penetration of different biodiesel blends (from B10 to B100) to the bus fleets are estimated....
Agushinta R., Dewi; Darmayantie, Astie; Rindhayanti, Hauliza; Permatasari, Jessica; H. S, D. Suryadi
The traffic jam becomes the biggest problem in urban area especially in Jakarta as the capital city of Indonesia. This is due to inadequate facilities of public transportation so, people prefers to use the private vehicles. The government has given the solution to enhance that but it is still not effective and it made the situation of traffic jam became worst. This paper proposed the Automated Bus System (ABS) to improve the existing system and enhance the traffic jam problem. This bus system has the ability to ride on his own without relying on any human driver. It can recognize any obstacles and avoid any collision using stereo vision technology. RFID technology is used to improve the accuracy. Still, this whole system is monitored by human operators. If there is any failure beyond the ability of system, the human operators could recognize the problem.
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...
Kegl, Breda; Kegl, Marko
This paper assembles and analyses extensive experimental research work conducted for several years in relation to biodiesel usage in a MAN bus Diesel engine with M injection system. At first the most important properties of the actually used neat rapeseed biodiesel fuel and its blends with mineral diesel are discussed and compared to that of mineral diesel. Then the injection, fuel spray, and engine characteristics for various considered fuel blends are compared at various ambient conditions,...
Zhang Zhenghui; Shen Ji; Wei Dongshan; Chen Ziyu
This article briefly introduces the developments of the parallel data grabbing card based on RS422 and PCI bus. It could be applied for grabbing the 14 bits parallel data in high speed, coming from the devices with RS422 interface. The methods of data acquisition which bases on the PCI protocol, the functions and their usages of the chips employed, the ideas and principles of the hardware and software designing are presented. (authors)
Tsao, H.-S. Jacob; Botha, Jan L.
Traffic congestion will continue to worsen and likely worsen at a faster rate than ever. People throughput and freight throughput have become critical issues for California and the rest of the nation. PATH has been funding a one-year research project entitled "Definition and Evaluation of Bus and Truck Automation Operations Concepts," proposed by the authors. This report summarizes the results of the research project achieved during the first six months. During those six months, we reviewed l...
S. Babaie-Kafaki; R. Ghanbari; S.H. Nasseri; E. Ardil
Bus networks design is an important problem in public transportation. The main step to this design, is determining the number of required terminals and their locations. This is an especial type of facility location problem, a large scale combinatorial optimization problem that requires a long time to be solved. The genetic algorithm (GA) is a search and optimization technique which works based on evolutionary principle of natural chromosomes. Specifically, the evolution o...
Eudy, L. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Post, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States)
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.
Malú de Oliveira Freire; Aline Rodrigues Barbosa; Lélia Renata das Virgens Carneiro; Raildo da Silva Coqueiro
To describe the signs of musculoskeletal disorders (SMD) in drivers and fare ollectors and to investigate their association with hours worked per day, nutritional status and level of physical activity (PA). A cross-sectional study undertaken with 40 bus drivers and 39 fare collectors working intercity routes. The “Nordic Musculoskeletal Questionnaire” was used to identify SMD. The working day was defi ned according to median values (< 8 hours or ≥ 8 hours). Level of PA was assessed using the...
Saez de Montagut Revenga, G.
This paper deals with the modification made in power plants nuclear ASCO 1 and 2 in which scans is the level Control system of Heaters to implementing an Ovation system, as well as the standard Foundation Field bus for field communications. This digitalisation has required a detailed study of the implications on security that could have the centralization of control loops in main feedwater system.
Rössner ml., Pavel; Švecová, Vlasta; Milcová, Alena; Lněničková, Zdena; Solanský, I.; Santella, R. M.; Šrám, Radim
Roč. 617, - (2007), s. 23-32 ISSN 0027-5107 R&D Projects: GA MŽP SL/5/160/05; GA AV ČR 1QS500390506 Institutional research plan: CEZ:AV0Z50390512 Keywords : oxidative stress * bus drivers * air pollution Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 4.159, year: 2007
Lee, Dongil; Lee, Myeongkyun; Yun, Donghwa; Ryoo, Kwangki
EtherCAT (Ethernet for Control Automation Technology) is based on the IEEE 802.3 standard as one of the communication which is the I/O (Input/Output), sensors and communication function of PLC (Programmable Logic Controller) in industry and factory environment use is increasing. The Nuclear Safety Class Controller implemented by the EtherCAT applied bus can be shown the improving performance of data transmission in the controller
Full Text Available School bus crashes are rare in comparison to other crash types, but considering all crashes that occur in and around school buses, they begin to become a noticeable problem and one that tends to attract national attention. As defined by the Fatality Analysis Reporting System (FARS, a school bus related crash is a crash that either involves a school bus or a crash where the presence of a school bus is considered as a major contributing factor. Ten years of data indicate that the number of fatal school bus related crashes has remained nearly stagnant despite an increase in the number vehicle safety systems available on the market. The findings also highlight the importance of protecting the non-bus occupants since they are the most likely to incur a serious or fatal injury in the event of a crash. As the most vulnerable user group, pedestrians (typically school-aged children are especially at risk when crossing the road while boarding or exiting a school bus. Until new technologies for reducing school bus related crashes are designed and implemented, school transportation safety can be improved by increasing awareness of school bus stop laws and by implementing existing transportation safety initiatives at school bus stop locations.
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.
Full Text Available A cellular automaton model is proposed to simulate mixed traffic flow composed of motor vehicles and bicycles near bus stops. Three typical types of bus stops which are common in China are considered in the model, including two types of curbside bus stops and one type of bus bay stops. Passenger transport capacity of three types of bus stops, which is applied to evaluate the bus stop design, is calculated based on the corresponding traffic flow rate. According to the simulation results, the flow rates of both motor vehicles and bicycles exhibit phase transition from free flow to the saturation one at the critical point. The results also show that the larger the interaction between motor vehicle and bicycle flow is near curbside bus stops, the more the value of saturated flows drops. Curbside bus stops are more suitable when the conflicts between two flows are small and the inflow rate of motor vehicles is low. On the contrary, bus bay stops should be applied due to their ability to reduce traffic conflicts. Findings of this study can provide useful suggestions on bus stop selection considering different inflow rate of motor vehicles and bicycles simultaneously.
Full Text Available 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.
Coutts, D.A.; Thomas, J.K.; Hovis, G.L.; Wu, T.T. [Westinghouse Savannah River Co., Aiken, SC (United States)
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.
Assunção, Ada Ávila; de Medeiros, Adriane Mesquita
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
Wade, Ted D; Hum, Richard C; Murphy, James R
Many clinical research data integration platforms rely on the Entity-Attribute-Value model because of its flexibility, even though it presents problems in query formulation and execution time. The authors sought more balance in these traits. Borrowing concepts from Entity-Attribute-Value and from enterprise data warehousing, the authors designed an alternative called the Dimensional Bus model and used it to integrate electronic medical record, sponsored study, and biorepository data. Each type of observational collection has its own table, and the structure of these tables varies to suit the source data. The observational tables are linked to the Bus, which holds provenance information and links to various classificatory dimensions that amplify the meaning of the data or facilitate its query and exposure management. The authors implemented a Bus-based clinical research data repository with a query system that flexibly manages data access and confidentiality, facilitates catalog search, and readily formulates and compiles complex queries. The design provides a workable way to manage and query mixed schemas in a data warehouse.
Arifin, Dadang; Yusuf, Edhi
This paper aims to develop a replacement model of city bus vehicles operated in Bandung City. This study is driven from real cases encountered by the Damri Company in the efforts to improve services to the public. The replacement model propounds two policy alternatives: First, to maintain or keep the vehicles, and second is to replace them with new ones taking into account operating costs, revenue, salvage value, and acquisition cost of a new vehicle. A deterministic dynamic programming approach is used to solve the model. The optimization process was heuristically executed using empirical data of Perum Damri. The output of the model is to determine the replacement schedule and the best policy if the vehicle has passed the economic life. Based on the results, the technical life of the bus is approximately 20 years old, while the economic life is an average of 9 (nine) years. It means that after the bus is operated for 9 (nine) years, managers should consider the policy of rejuvenation.
Ada Ávila Assunção
Full Text Available 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.
Full Text Available Vibration comfort is an important factor affecting the quality of service (QoS of bus. In order to make people involved in supervising bus’s vibration comfort and improve passengers’ riding experience, a novel mode of passenger crowdsourcing is introduced. In this paper, comfort degree of bus vibration is calculated from bus’s vibration signals collected by passengers’ smartphones and sent through WiFi to the Boa web server which shows the vibration comfort on the LCD deployed in bus and maybe trigger alarm lamp when the vibration is beyond the threshold. Three challenges here have been overcome: firstly, space coordinate transformation algorithm is used to solve the constant drift of signals collected; secondly, a low-pass filter is designed to isolate gravity from signals real-timely via limited computing resources; thirdly, an embedded evaluation system is developed according to the calculation procedure specified by criterion ISO 2631-1997. Meanwhile, the model proposed is tested in a practical running environment, the vibration data in whole travel are recorded and analyzed offline. The results show that comfort degree of vibration obtained from the experimental system is identical with the truth, and this mode is proved to be effective.
Ankit Kumar Begwani
Full Text Available Rapid but unplanned urban development coupled with economic growth has resulted in congestion and pollution concerns in Indian cities. This forced India consider taking concrete steps towards design policies that would help stir the nation towards a more sustainable future. India, along with other bigger Asian economies like China, needs to address the growing global concerns over climate change and design their framework and policies to help cut down the greenhouse gas emissions. Transportation is a major source of pollution. A shift towards a pro-public transport policy would solve the traffic congestion problems and address the emission concerns. India has a significantly higher modal share of public transportation in its major cities. Public bus transport system acts as a lifeline to the India’s poor and middle class citizens. The following study focuses on the need for a replacement of conventional fossil fuel dependent buses with Electric buses in the existing public transport bus fleet in the city of Bengaluru. A design has been developed to utilize wireless charging technologies to realize electric bus migration in Bengaluru.
Full Text Available The HEV test bench based on Controller Area Network bus was studied and developed. Control system of HEV power test bench used the CAN bus technology. The application of CAN bus technology on control system development has opened up a new research direction for domestic automobile experimental platform. The HEV power control system development work was completed, including power master controller, electric throttle controller, driving simulation platform, CAN2.0 B communication protocol procedures for formulation, CAN communication monitoring system, the simulation model based on MATLAB code automatic generation technology research, etc. Maximum absorption power of the test bench is 90 kW, the test bench top speed is 6000 r/min, the CAN communication data baud rate is 10~500 k, the conventional electric measurement parameter part precision satisfies the requirement of development of HEV. On the HEV test bench the result of regenerative braking experiment shows that the result got by the test bench was closer to the results got by outdoor road test. And the fuel consumption experiment test results show that the HEV fuel consumption and the charge-discharge character are in linear relationship. The establishment of the test platform for the evaluation of the development of hybrid electric vehicle and power provides physical simulation and test platform.
Hadaegh, F. Y.; Smith, R. S.
A formation of satellites flying in deep space can be specified in terms of the relative satellite positions and absolute satellite orientations. The redundancy in the relative position specification generates a family of control topologies with equivalent stability and reference tracking performance, one of which can be implemented without requiring communication between the spacecraft. A relative position design formulation is inherently unobservable, and a methodology for circumventing this problem is presented. Additional redundancy in the control actuation space can be exploited for feed-forward control of the formation centroid's location in space, or for minimization of total fuel consumption.
Full Text Available This paper is concerned with the attitude control of a three-axis-stabilized spacecraft which consists of a central rigid body and a flexible sun-tracking solar array driven by a solar array drive assembly. Based on the linearization of the dynamics of the spacecraft and the modal identities about the flexible and rigid coupling matrices, the spacecraft attitude dynamics is reduced to a formally singular system with periodically varying parameters, which is quite different from a spacecraft with fixed appendages. In the framework of the singular control theory, the regularity and impulse-freeness of the singular system is analyzed and then admissible attitude controllers are designed by Lyapunov’s method. To improve the robustness against system uncertainties, an H∞ optimal control is designed by optimizing the H∞ norm of the system transfer function matrix. Comparative numerical experiments are performed to verify the theoretical results.
Aerospace projects have traditionally employed federated avionics architectures, in which each computer system is designed to perform one specific function (e.g. navigation). There are obvious downsides to this approach, including excessive weight (from so much computing hardware), and inefficient processor utilization (since modern processors are capable of performing multiple tasks). There has therefore been a push for integrated modular avionics (IMA), in which common computing platforms can be leveraged for different purposes. This consolidation of multiple vehicle functions to shared computing platforms can significantly reduce spacecraft cost, weight, and design complexity. However, the application of IMA principles introduces significant challenges, as the data network must accommodate traffic of mixed criticality and performance levels - potentially all related to the same shared computer hardware. Because individual network technologies are rarely so competent, the development of truly integrated network architectures often proves unreasonable. Several different types of networks are utilized - each suited to support a specific vehicle function. Critical functions are typically driven by precise timing loops, requiring networks with strict guarantees regarding message latency (i.e. determinism) and fault-tolerance. Alternatively, non-critical systems generally employ data networks prioritizing flexibility and high performance over reliable operation. Switched Ethernet has seen widespread success filling this role in terrestrial applications. Its high speed, flexibility, and the availability of inexpensive commercial off-the-shelf (COTS) components make it desirable for inclusion in spacecraft platforms. Basic Ethernet configurations have been incorporated into several preexisting aerospace projects, including both the Space Shuttle and International Space Station (ISS). However, classical switched Ethernet cannot provide the high level of network
The thesis deals with the relative navigation between two small formation flying spacecraft. The inter-satellite distance is measured using locally generated radiofrequency ranging signals. Design considerations for the spacecraft and the relative navigation system are discussed as well as the
Bozzano, Marco; Cimatti, Alessandro; Katoen, Joost P.; Katsaros, Panagiotis; Mokos, Konstantinos; Nguyen, Viet Yen; Noll, Thomas; Postma, Bart; Roveri, Marco
The size and complexity of software in spacecraft is increasing exponentially, and this trend complicates its validation within the context of the overall spacecraft system. Current validation methods are labor-intensive as they rely on manual analysis, review and inspection. For future space
Norcross, Scott; Grieser, William H.
This paper describes a product called the Intelligent Mission Toolkit (IMT), which was created to meet the changing demands of the spacecraft command and control market. IMT is a command and control system built upon an expert system. Its primary functions are to send commands to the spacecraft and process telemetry data received from the spacecraft. It also controls the ground equipment used to support the system, such as encryption gear, and telemetry front-end equipment. Add-on modules allow IMT to control antennas and antenna interface equipment. The design philosophy for IMT is to utilize available commercial products wherever possible. IMT utilizes Gensym's G2 Real-time Expert System as the core of the system. G2 is responsible for overall system control, spacecraft commanding control, and spacecraft telemetry analysis and display. Other commercial products incorporated into IMT include the SYBASE relational database management system and Loral Test and Integration Systems' System 500 for telemetry front-end processing.
Recent science and technology advancements of micro and nanosatellites have opened possibilities for new space missions that would otherwise be impossible to be carried out by small spacecraft. The Space Flight Laboratory, located at the University of Toronto Institute for Aerospace Studies, is one of the worldwide leaders in small satellite development. The Space Flight Laboratory's capabilities and technology are considered in two concept studies addressed in this thesis. In one study, the adaptation of the Generic Nanosatellite Bus for a high-precision astronomical calibration mission is explored. The bus expands the capabilities of low-cost nanosatellites by accommodating large and complex payloads. In another study, the NEMO-AM platform is adapted to a mission intended for quantum physics experiments from space, based on the demanding payload requirements. These two studies confirm the capabilities of the Space Fight Lab in undertaking innovative space missions at a fraction of the cost. Lastly, the design and development of a multi-mission telemetry data management system is described. This system is designed and built from the ground up, and has been put into operational use at the Space Flight Laboratory.
The international economy, in the beginning of the 20th century, is characterized by uncertainty about the supply and the price of oil. Together with the fast decrease of electrical propulsion component prices, it becomes more and more cost effective to develop vehicles with alternative powertrains. This paper focuses on two questions: Are alternative powertrains especially cost effective for specific applications?; How does an increased fossil fuel price influences the choose of powertrain? To assess these questions, a computer tool named THEPS, developed in a Ph.D. project, is used. Three applications and three scenarios are analysed. The applications, a car, a city bus and an intercity bus, are vehicles all assumed to operate in Sweden. One scenario represents year 2005, the other two year 2020. The two future scenarios are characterized by different fossil fuel prices. The study, presented in the paper, indicates that alternative powertrains can be competitive from a cost perspective, in some applications, already in year 2005. It is for example cost effective to equip a city bus, running in countries with a high fuel price, with a hybrid powertrain. The study also indicates that pure electric, hybrid and/or fuel cell cars will probably be a more cost effective choice than conventional cars in year 2020. Another indication is that it will not be clear which powertrain concept to choose. The reason is that many cost effective powertrain concepts will be offered. The best choice will depend on the application
Ahlström, Christer; Gink Lövgren, Maria; Nilsson, Mats; Willstrand, Tania; Anund, Anna
City bus drivers spend hours driving under time pressure, in congested traffic and in a monotonous sitting position. This leads to unhealthy working conditions, especially in terms of physical and psychological stress. The aim of this study is to investigate if an active steering system can alleviate the musculoskeletal stress involved in manoeuvring a bus. Twenty bus drivers drove a city bus equipped with the Volvo dynamic steering (VDS) support system in real traffic. Steering effort was evaluated with fyography and with a questionnaire. Compared to baseline, VDS significantly reduced the required muscle activity by on average 15 - 25 % while turning, and with up to 68 % in the part of the manoeuvre requiring maximum effort. The bus drivers believed that VDS will help reduce neck and shoulder problems, and they expressed a desire to have VDS installed in their own bus.
Full Text Available Even though WM-Bus is being considered to be the most promising network protocol for smart metering, it is not suitable for a sustainable real-time home energy management system (HEMS, which requires higher reliability and longer lifetime despite real time bi-directional communications. Therefore, in this paper we propose a Bitmap-wise WM-Bus (BWM-Bus, coping well with sustainable real-time HEMS. In particular, the proposed scheme addresses the several problems in WM-Bus for HEMS by introducing novel functions: asynchronous meter trigger, adaptive slot scheduling, and bitmap-wise retransmission request. Through experiments, we demonstrate that BWM-Bus guarantees higher data success ratio with lower data aggregation time, as well as longer lifetime than WM-Bus standard.
Full Text Available According to different driving behavioral characteristics of bus drivers, a cellular automata traffic model considering the bus lane changing behavior with scheduling parameters is proposed in this paper. Traffic bottleneck problems caused by bus stops are simulated in multiple lanes roads with no-bay bus stations. With the mixed traffic flow composed of different bus arrival rate, flow-density graph, density distribution graph, and temporal-spatial graph are presented. Furthermore, the mixed traffic flow characteristics are analyzed. Numerical experiment results show that the proposed model can generate a variety of complicated realistic phenomena in the traffic system with bus stops and provide theoretical basis for better using of traffic flow model.
Mizokami, Shoshi; Fujimi, Toshio; Hirano, Toshihiko
Recently, the number of passenger of public bus services in Japan tends to decrease due to the motorization. This condition leads to a severe management situation, including in Kumamoto City. Since 1984, the deficit of bus companies operation in provision of bus services in Kumamoto has been covered by Kumamoto City Government on the basis of lines subsidy, and the city allocated a number of subsidy of about 200 million yen in 2007. Currently, The Kumamoto city government plans to reduce the amount of subsidy to bus companies by introducing the giving of incentive to bus companies in order to trim bus company deficit. This study aims to construct the mathematical model of the incentive reward and apply the model to realignment of buses lines networks in Kumamoto Metropolitan Area.
Eudy, L.; Chandler, K.
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.
M.A. The purpose of the study was to investigate the relationship between job involvement and job satisfaction between the traffic officers and bus drivers of the Germiston Transitional Local Council. The following research questions were addressed: What are the levels of job involvement and job satisfaction that traffic officers and bus drivers experience? How does job involvement and job satisfaction of traffic officers and bus drivers compare? What is the relationship between job involv...
Fonzone, Achille; Schmöcker, Jan-Dirk; Liu, Ronghui
If bus service departure times are not completely unknown to the passengers, non-uniform passenger arrival patterns can be expected. We propose that passengers decide their arrival time at stops based on a continuous logit model that considers the risk of missing services. Expected passenger waiting times are derived in a bus system that allows also for overtaking between bus services. We then propose an algorithm to derive the dwell time of subsequent buses serving a stop in order to illustr...
Flanegan, Mark; Label, Ken
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.
Full Text Available Bus system performance varies from city to city, and experience clearly indicates that simply increasing the size of bus fleet cannot always improve bus system performance. It is therefore necessary to identify the major variables of bus system performance in different cities and implement a diversity improvement strategy based on actual problems that cities are facing. Two new indicators, annual average bus trips per capita and average daily ridership per bus, are proposed to respectively describe two aspects of bus system performance: willingness to travel and operational efficiency. According to these two indicators, 645 cities in China are classified into four types: cities with good performance in both aspects; in only one aspect; and in neither aspect. Then, based on panel data attained during 2002–2008, the impacts of the variables on willingness to travel and operational efficiency in different city types are analyzed by the variable coefficient model. The results show that the impacts of urban geography, economic conditions, and bus system facility vary among the four city types. Bus ownership ratio has a significant positive impact on improving willingness to travel for the cities with insufficient bus system facility. However, the impact decreases in the cities with well-developed facilities, whereas the operational efficiency suffers from negative impact due to the excess in bus system facility. In addition, the development characteristics of the cities that are improved both in willingness to travel and operational efficiency in each city type during 2002–2008 are discussed. The findings can help local governments make more specific, reasonable and efficient strategies to promote bus system performance.
MUHAMMAD WAQAR ASLAM
Full Text Available This research work has evaluated the performance of urban public bus transport service operating in Gujranwala city of Pakistan. The assessment has been made in terms of financial viability, bus condition, operational performance and user perception. Based on the data requirements, various traffic/transport surveys were conducted including Passenger Boarding and Alighting Survey, Bus Count Survey, Bus Inspection Survey, Illegal Operations Survey and Public Transport User Interview Survey in consultation with concerned department/agencies. Field surveys were also conducted to get input from passengers and local people. Initial investigation informed that out of four operational bus routes, only two routes are profitable. The overall bus operation is running in loss (only 0.3% net profit. It has barely any profit for the bus operator against its investment thereby making the urban bus operation financially non-viable. The whole revenue flow is dependent on passenger ticketing revenue only. Around 35% of the buses are in poor condition with major issues of quality of tyres, no speedometer, worse condition of seats, floor and ceiling, and display of route. Illegal operation of Qingqis/Rickshaws (as para-transit mode along the bus routes is also decreasing the revenue by capturing the passenger volume. According to passenger opinion analysis, around 55% of the passenger are not satisfied with the service quality and prefer other modes of transport. Their major concerns are absence of facilities for disables and bus stops, bus seating and standing capacity, poor bus condition and pick pocketing. Collectively, these factors are contributing
The major thrust was to develop a T coupler with very low (0.1 0.2dB) in-line loss. This is essential to any multiaccess bus structure where the word multi implies fifteen or more nodes on the bus, and it is tacitly assumed to be a passive bus. (Reliability considerations tend to exclude the use of active nodes - repeater nodes.)
Energy Sector Management Assistance Program
In most large cities in developing countries, buses continue to be the public transport option of choice, carrying a large share of urban travelers. However, transit bus companies in these countries are often cash-strapped. In many cases, the operating cost per bus kilometer exceeds revenues and bus fares are often kept low irrespective of the cost of providing service. Many cities are dom...
The determination of bus service frequency using cost-benefit approach is presented in this paper. This study was conducted in Malaysia where bus operators could provide feasible bus services using this method. The investment costs include all costs for vehicle, human resources, workshop, operational facilities, andsupporting facilities while the benefits are expected from ticket fare collected and fuel subsidy. The primary data consists of passenger number, ticket fare, travel time, number o...
Seffrin, R. James
Electrical bus duct is a common feature in both manufacturing facilities and high rise buildings. In the past, bus duct testing involved labor-intensive manual inspection and maintenance and a significant power outage. Infrared thermography can be useful in situations where bus duct loads are balanced and uniform; however, these conditions are not usually found in the field. Resistive load banks combined with infrared thermography provide a controlled and accurate non-destructive test method for electrical bus ducts. Labor and downtime are both reduced and testing may be varied from light to full load.
Donoughe, Kelly; Katz, Bryan
School bus crashes are rare in comparison to other crash types, but considering all crashes that occur in and around school buses, they begin to become a noticeable problem and one that tends to attract national attention. As defined by the Fatality Analysis Reporting System (FARS), a school bus related crash is a crash that either involves a school bus or a crash where the presence of a school bus is considered as a major contributing factor. Ten years of data indicate that the number of fat...
Shea, M.F.; Goodwin, R.W.; Kucera, M.J.; Shtirbu, S.
Data acquisition hardware in accelerator control systems is connected by a field bus to networked computers that supply data to consoles. Industry attempts to standardize on a low level field bus have not succeeded in providing a single well-supported bus. This paper describes a data acquisition chassis that connects to VMEbus computers using ARCNET, a full featured token-passing local area network, as the field bus. The performance of this technique as implemented in the control system for the Fermilab Linac is given. (author)
Full Text Available Along with the evolution of times and the surge of metropolitan populations, government agencies often promote the construction of public transport. Unlike rail transportation or rapid transit systems, it is often difficult to estimate the vehicle arrival times at each station in a bus transportation system due to metropolitan transportation congestion. Traffic status is often monitored using wireless sensor networks (WSNs. However, WSNs are always separated from one another spatially. Recent studies have considered the connection of multiple sensor networks. This study considers a combination view of peer-to-peer (P2P overlay networks and WSN architecture to predict bus arrival times. Each bus station, which is also a P2P overlay peer, is connected in a P2P overlay network. A sensor installed in each bus can receive data via peers to obtain the moving speed of a bus. Then, each peer can exchange its data to predict bus arrival times at bus stations. This method can considerably increase the accuracy with which bus arrival times can be predicted and can provide traffic status with high precision. Furthermore, these data can also be used to plan new bus routes according to the information gathered.
Shen, Xianghao; Feng, Shumin; Li, Zhenning; Hu, Baoyu
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.
Wang, Hsiao-Lan; Chen, Ya-Ping; Rau, Chi-Lun; Yu, Chung-Huang
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.
Full Text Available During service, a bus is subjected to various loads that cause stresses, vibrations and noise in the different components of its structure. It requires appropriate strength, stiffness and fatigue properties of the components to be able to stand these loads. Besides, quality and optimum weight of the vehicle, for efficient energy consumption, safety and provision of the comfort to the user are highly desired. The present work proposes a methodology to minimize the bus weight by modifying its beam gauges to optimum thickness. The bus performance is evaluated by multiple iterations on the basis of parameters like frequency, distortion, stress and stiffness. The algorithm performs gauge optimization of the bus by analyzing and satisfying its structural strength through linear static analysis on a laden bus. It also performs structural stiffness analysis and vibration analysis for safety of the bus structure. This work unfolds an integrated methodology to the bus manufacturers to optimize the structural weight for improving the fuel efficiency, static and dynamic safety, and robust design. The work is implemented by creating a finite element model of the bus and optimizing in HyperWorks environment. The results are verified for a full length 11 m, 65 seats bus. The methodology helps in weight reduction along with improvement in performance parameters.
Ngo, Nicole S
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.
Li, Shuang; Chen, Shuguang; Zhu, Lizhong; Chen, Xiasheng; Yao, Chaoying; Shen, Xueyou
Air pollution surveys of ten selected monoaromatic hydrocarbons (MAHCs) were conducted in buses and bus stations in Hangzhou, China. The mean concentrations of MAHCs in the air of buses and bus stations were 95.9 and 36.5 microg/m(3), respectively, of which toluene was the highest in all the sampling sites. Mean concentrations of all MAHCs in buses were statistically higher than those nearby bus stations (pbus drivers were 1.11x10(-5) and 4.00x10(-5), respectively, which were way above the limit set by USEPA. The health risk caused by MAHCs in bus microenvironment should be cautioned.
Nobrega, F.; Brandt, J.; Cheban, S.; Feher, S.; Kaducak, M.; Kashikhin, V.; Peterson, T.
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.
It means whole system stability assessment is equal to a special generator pair stability assessment. EAC may be applied to the generator pair through a new way (Fang, 2009). 4. Theory of Single Machine-Infinite Bus System. 4.1 Power Transfer Equation. For a simple lossless transmission line connecting a generator and ...
Pencil, Eric J.; Sarmiento, Charles J.; Lichtin, D. A.; Palchefsky, J. W.; Bogorad, A. L.
Application of electrothermal arcjets on communications satellites requires assessment of integration concerns identified by the user community. Perceived risks include plume contamination of spacecraft materials, induced arcing or electrostatic discharges between differentially charged spacecraft surfaces, and conducted and radiated electromagnetic interference (EMI) for both steady state and transient conditions. A Space Act agreement between Martin Marietta Astro Space, the Rocket Research Company, and NASA's Lewis Research Center was established to experimentally examine these issues. Spacecraft materials were exposed to an arcjet plume for 40 hours, representing 40 weeks of actual spacecraft life, and contamination was characterized by changes in surface properties. With the exception of the change in emittance of one sample, all measurable changes in surface properties resulted in acceptable end of life characteristics. Charged spacecraft samples were benignly and consistently reduced to ground potential during exposure to the powered arcjet plume, suggesting that the arcjet could act as a charge control device on spacecraft. Steady state EMI signatures obtained using two different power processing units were similar to emissions measured in a previous test. Emissions measured in UHF, S, C, Ku and Ka bands obtained a null result which verified previous work in the UHF, S, and C bands. Characteristics of conducted and radiated transient emissions appear within standard spacecraft susceptibility criteria.
Pleil, Joachim D; Hansel, Armin
Foreword The International Association of Breath Research (IABR) meetings are an eclectic gathering of researchers in the medical, environmental and instrumentation fields; our focus is on human health as assessed by the measurement and interpretation of trace chemicals in human exhaled breath. What may have escaped our notice is a complementary field of research that explores the creation and maintenance of artificial atmospheres practised by the submarine air monitoring and air purification (SAMAP) community. SAMAP is comprised of manufacturers, researchers and medical professionals dealing with the engineering and instrumentation to support human life in submarines and spacecraft (including shuttlecraft and manned rockets, high-altitude aircraft, and the International Space Station (ISS)). Here, the immediate concerns are short-term survival and long-term health in fairly confined environments where one cannot simply 'open the window' for fresh air. As such, one of the main concerns is air monitoring and the main sources of contamination are CO(2) and other constituents of human exhaled breath. Since the inaugural meeting in 1994 in Adelaide, Australia, SAMAP meetings have been held every two or three years alternating between the North American and European continents. The meetings are organized by Dr Wally Mazurek (a member of IABR) of the Defense Systems Technology Organization (DSTO) of Australia, and individual meetings are co-hosted by the navies of the countries in which they are held. An overriding focus at SAMAP is life support (oxygen availability and carbon dioxide removal). Certainly, other air constituents are also important; for example, the closed environment of a submarine or the ISS can build up contaminants from consumer products, cooking, refrigeration, accidental fires, propulsion and atmosphere maintenance. However, the most immediate concern is sustaining human metabolism: removing exhaled CO(2) and replacing metabolized O(2). Another
Golan, Ron; Soffer, Dror; Givon, Adi; Peleg, Kobi
Terrorist explosions occurring in varying settings have been shown to lead to significantly different injury patterns among the victims, with more severe injuries generally arising in confined space attacks. Increasing numbers of terrorist attacks have been targeted at civilian buses, yet most studies focus on events in which the bomb was detonated within the bus. This study focuses on the injury patterns and hospital utilisation among casualties from explosive terrorist bus attacks with the bomb detonated either within a bus or adjacent to a bus. All patients hospitalised at six level I trauma centres and four large regional trauma centres following terrorist explosions that occurred in and adjacent to buses in Israel between November 2000 and August 2004 were reviewed. Injury severity scores (ISS) were used to assess severity. Hospital utilisation data included length of hospital stay, surgical procedures performed, and intensive care unit (ICU) admission. The study included 262 victims of 22 terrorist attacks targeted at civilian bus passengers and drivers; 171 victims were injured by an explosion within a bus (IB), and 91 were injured by an explosion adjacent to a bus (AB). Significant differences were noted between the groups, with the IB population having higher ISS scores, more primary blast injury, more urgent surgical procedures performed, and greater ICU utilisation. Both groups had percentages of nearly 20% for burn injury, had high percentages of injuries to the head/neck, and high percentages of surgical wound and burn care. Explosive terrorist attacks detonated within a bus generate more severe injuries among the casualties and require more urgent surgical and intensive level care than attacks occurring adjacent to a bus. The comparison and description of the outcomes to these terrorist attacks should aid in the preparation and response to such devastating events. Copyright © 2013 Elsevier Ltd. All rights reserved.
The Federal Transit Administration's National Fuel Cell Bus Program focuses on developing commercially viable fuel cell bus technologies. Nuvera is leading the Massachusetts Fuel Cell Bus project to demonstrate a complete transit solution for fuel cell electric buses that includes one bus and an on-site hydrogen generation station for the Massachusetts Bay Transportation Authority (MBTA). A team consisting of ElDorado National, BAE Systems, and Ballard Power Systems built the fuel cell electric bus, and Nuvera is providing its PowerTap on-site hydrogen generator to provide fuel for the bus.
Love, Stanley G.; Morin, Lee M.; McCabe, Mary
Fifty years ago, NASA decided that the cockpit controls in spacecraft should be like the ones in airplanes. But controls based on the stick and rudder may not be best way to manually control a vehicle in space. A different method is based on submersible vehicles controlled with foot pedals. A new pilot can learn the sub's control scheme in minutes and drive it hands-free. We are building a pair of foot pedals for spacecraft control, and will test them in a spacecraft flight simulator.
The Physics Bus is about doing science for fun. It is an innovative model for science outreach whose mission is to awaken joy and excitement in physics for all ages and walks of life - especially those underserved by science enrichment. It is a mobile exhibition of upcycled appliances-reimagined by kids-that showcase captivating physics phenomena. Inside our spaceship-themed school bus, visitors will find: a microwave ionized-gas disco-party, fog rings that shoot from a wheelbarrow tire, a tv whose electron beam is controlled by a toy keyboard, and over 20 other themed exhibits. The Physics Bus serves a wide range of public in diverse locations from local neighborhoods, urban parks and rural schools, to cross-country destinations. Its approachable, friendly and relaxed environment allows for self-paced and self-directed interactions, providing a positive and engaging experience with science. We believe that this environment enriches lives and inspires people. In this presentation we will talk about the nuts and bolts that make this model work, how the project got started, and the resources that keep it going. We will talk about the advantages of being a grassroots and community-based organization, and how programs like this can best interface with universities. We will explain the benefits of focusing on direct interactions and why our model avoids ``teaching'' physics content with words. Situating our approach within a body of research on the value of informal science we will discuss our success in capturing and engaging our audience. By the end of this presentation we hope to broaden your perception of what makes a successful outreach program and encourage you to value and support alternative outreach models such as this one. In Collaboration with: Eva Luna, Cornell University; Erik Herman, Cornell University; Christopher Bell, Ithaca City School District.
Alex, T. K.; Jain, Y. K.; Philip, M. P.; Kalakrishnan, B.; Kanakaraju, K.; Kamalakar, J. A.
A variety of attitude sensors have been used in the Ariane Passenger Payload Experiment (APPLE) geosynchronous satellite's control system. Sensor tasks encompass satellite attitude determination after separation from launch vehicle, spin axis orientation for apogee boost motor firing and satellite spin-up, satellite despin and sunward pointing on reaching geosynchronous orbit, three-axis stabilization, and yaw axis control during stationkeeping. Attention is given to problems encountered during APPLE deployment, of which the most serious was the failure of one of the solar panels to deploy. Pitch rotation was used to keep earth sensor temperature below operating maximum range.
Xylia, Maria; Silveira, Semida
The Swedish public transport sector has defined two major targets, i.e., to run 90% of the total vehicle kilometers of the fleet on non-fossil fuels and double the volume of travel via public transport by 2020, increasing the share of public transport in relation to the total personal transport in the country . The f3 report Fuel options for public bus fleets in Sweden highlights the challenges and solutions encountered, particularly when it comes to the adoption of renewable fuels in the reg...
Eudy, L.; Post, M.
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.
STUDY OF AVIONICS TIME DIVISION MULTIPLEX BUS SIMULATION, For Period Covering ’? *-" . (. I Janu wry k~t-4-31 Decoe 380 tP_: Final Report -, - / -AFOSR...simulation modeling is a type of art work, and therefore requires a talented engineer. Furthermore, the complexity of the sys- tem may be such that it is...used to synchronize the movement of the assembly set. Operand: X field specifies the block number of a MATCH block. Condition for entry acceptance: It
Li, Yushuang; Chen, Libing; Men, Tao; Yang, Qingfeng; Li, Ning; Nie, Tao
The power amplifier is an important part of the high power digital transceiver module, because of its great demand and diverse measurement indicators, an automatic test system is designed to meet the production requirements of the power amplifiers as the manual test cannot meet the demand of consistency. This paper puts forward the plan of the automatic test system based on LXI bus technology, introduces the hardware and software architecture of the system. The test system has been used for debugging and testing the power amplifiers stably and efficiently, which greatly saves work force and effectively improves productivity.
Limasset, J C; Diebold, F; Hubert, G
Two measurement campaigns aimed at measuring the air pollutant emissions of vehicles (carbon monoxide, nitrogen oxides, lead, benzo[a]pyrene and formaldehyde) have been carried out using on-board sampling or analysis equipment in public buses in two major French towns. The study had a double objective: (i) to assess the occupational exposure through pollutant measurements in the breathing zone of the drivers at their working posts, (ii) to compare the quality of the air sampled outside, either at the bus front (current position of the ventilation air intake), or on the vehicle roof. Carbon monoxide measurements were performed with several Ecolyser (electrochemical detection) standardized with a Mahiak Unor 6N infra-red non-dispersive analyser and nitrogen mono- and dioxide with AC 30 M Environment S.A. analysers (chemiluminescent detection), with a data-logger recording the '5-min weighted average concentrations'. Lead on dust was sampled on cellulose acetate or quartz filters and analysed by atomic absorption, benzo[a]pyrene (as a tracer of polynuclear hydrocarbons) on quartz filters and by HPLC/UV fluorescence detector and formaldehyde (as a tracer of aldehydes) on 2,4-DNPH-impregnated silicagel tubes by HPLC/UV. Recording and sampling were performed for 18 single and return routes in the center of Paris (for 1.5-2 h each) and for 25 routes in the center of Bordeaux (for 35-60 min). The results clearly indicate that the occupational exposures of urban bus drivers for the six pollutants are lower than the exposure limit values in the working place (French Labour Department or A.C.G.I.H. standards). In particular, levels for benzopyrene, associated with carcinogenic hazard, do not increase 5% of the standard from Russian origin (150 ng/m3). On the contrary, concentrations reached the levels recommended by international air quality standards (OMS, US or European standards) for carbon monoxide, nitrogen dioxide and lead. When CO mean concentration values by bus lines
Mi, Xueqiang; Tang, Xinhuai; Yuan, Xiaozhou; Chen, Delai; Luo, Xiangfeng
Message Routing is the foremost functionality on Enterprise Service Bus (ESB), but current ESB products don't provide an expected solution for it, especially in the aspects of runtime route change mechanism and service orchestration model. In order to solve the above drawbacks, this paper proposes a multifactor-driven hierarchical routing (MDHR) model. MDHR defines three layers for message routing on ESB. Message layer gives the original support for message delivery. Application layer can integration or encapsulate some legacy applications or un-standard services. Business layer introduces business model to supplies developers with a business rule configuration, which supports enterprise integration patterns and simplifies the service orchestration on ESB.
National Aeronautics and Space Administration — Please note that funding to Dr. Simon Hsiang, a critical co-investigator for the development of the Spacecraft Optimization Layout and Volume (SOLV) model, was...
National Aeronautics and Space Administration — This utility permits you to download the most current version of the spacecraft (FT2) file predicting the LAT's pointing for a given mission week. The FT2 file is a...
Hwu, Shian U.; Desilva, Kanishka; Sham, Catherine C.
The Communication Systems Simulation Laboratory (CSSL) at the NASA Johnson Space Center is tasked to perform spacecraft and ground network communication system simulations, design validation, and performance verification. The CSSL has developed simulation tools that model spacecraft communication systems and the space and ground environment in which the tools operate. In this paper, a spacecraft communication system with multiple arrays is simulated. Multiple array combined technique is used to increase the radio frequency coverage and data rate performance. The technique is to achieve phase coherence among the phased arrays to combine the signals at the targeting receiver constructively. There are many technical challenges in spacecraft integration with a high transmit power communication system. The array combining technique can improve the communication system data rate and coverage performances without increasing the system transmit power requirements. Example simulation results indicate significant performance improvement can be achieved with phase coherence implementation.
National Aeronautics and Space Administration — We propose to design, build and test an optical extinction monitor for the detection of spacecraft cabin particulates. This monitor will be sensitive to particle...
National Aeronautics and Space Administration — We have built and tested an optical extinction monitor for the detection of spacecraft cabin particulates. This sensor sensitive to particle sizes ranging from a few...
There is an ongoing discussion about the participation of women in science and particularly astronomy. Demographic data from NASA's robotic planetary spacecraft missions show women scientists to be consistently under-represented.
National Aeronautics and Space Administration — Spacecraft fires create exception risks to crew members. There is usually no place to escape. Even small amounts of hardware damage can compromise a mission. The...
Horvath, Joan C.; Alkalaj, Leon J.; Schneider, Karl M.; Spitale, Joseph M.; Le, Dang
Robotic spacecraft are controlled by onboard sets of commands called "sequences." Determining that sequences will have the desired effect on the spacecraft can be expensive in terms of both labor and computer coding time, with different particular costs for different types of spacecraft. Specification languages and appropriate user interface to the languages can be used to make the most effective use of engineering validation time. This paper describes one specification and verification environment ("SAVE") designed for validating that command sequences have not violated any flight rules. This SAVE system was subsequently adapted for flight use on the TOPEX/Poseidon spacecraft. The relationship of this work to rule-based artificial intelligence and to other specification techniques is discussed, as well as the issues that arise in the transfer of technology from a research prototype to a full flight system.
National Aeronautics and Space Administration — Spacecraft and lunar bases generate a variety of wastes containing water, including food wastes, feces, and brines. Disposal of these wastes, as well as recovery of...
Attitude dynamics is the theoretical basis of attitude control of spacecrafts in aerospace engineering. With the development of nonlinear dynamics, chaos in spacecraft attitude dynamics has drawn great attention since the 1990's. The problem of the predictability and controllability of the chaotic attitude motion of a spacecraft has a practical significance in astronautic science. This book aims to summarize basic concepts, main approaches, and recent progress in this area. It focuses on the research work of the author and other Chinese scientists in this field, providing new methods and viewpoints in the investigation of spacecraft attitude motion, as well as new mathematical models, with definite engineering backgrounds, for further analysis. Professor Yanzhu Liu was the Director of the Institute of Engineering Mechanics, Shanghai Jiao Tong University, China. Dr. Liqun Chen is a Professor at the Department of Mechanics, Shanghai University, China.
National Aeronautics and Space Administration — For spacecraft developers who spend millions to billions of dollars per unit and require 3 to 7 years to deploy, the LoadPath reduced-order (RO) modeling thermal...
National Aeronautics and Space Administration — Fractionated spacecraft architectures to distribute mission performance from a single, monolithic satellite across large number of smaller spacecraft, for missions...
McCamish, Shawn B
This research contributes to multiple spacecraft control by developing an autonomous distributed control algorithm for close proximity operations of multiple spacecraft systems, including rendezvous...
Li, Haiyang; Li, Jingyang; Jiang, Fanghua
Tumbling debris has become a great threat to orbit activities. Contactless interaction is a novel concept for active debris removal, through which the tumbling debris no longer rotates freely but is under control. The contactless interaction method aims to de-tumble the debris and then maintain desired relative states between the spacecraft and debris. The spacecraft is simultaneously stabilized through three-axis attitude control, which makes the de-tumbling and capture operation much safer, more effective and accurate. The dynamics and control for the contactless interaction have been little studied in the past years. This paper considers a generic dynamics and control problem for contactless interaction between a spacecraft and debris. A translational and rotational dynamics model of contactless interaction is proposed and the 6-DOF equations are established. The contactless interaction control law is designed with the backstepping method, and the spacecraft three-axis control law is designed with the PD control. Simulation results show that the angular momentum is transferred from the debris to the spacecraft and the debris is thus de-tumbled. The desired relative states are achieved efficiently. Significantly, the spacecraft and debris no longer rotate in the inertial frame and, hence, the safety and accuracy for capture operation are guaranteed.
Full Text Available In this paper a classical lead-lag power system stabilizer is used for demonstration. The stabilizer parameters are selected in such a manner to damp the rotor oscillations. The problem of selecting the stabilizer parameters is converted to a simple optimization problem with an eigen value based objective function and it is proposed to employ simulated annealing and particle swarm optimization for solving the optimization problem. The objective function allows the selection of the stabilizer parameters to optimally place the closed-loop eigen values in the left hand side of the complex s-plane. The single machine connected to infinite bus system and 10-machine 39-bus system are considered for this study. The effectiveness of the stabilizer tuned using the best technique, in enhancing the stability of power system. Stability is confirmed through eigen value analysis and simulation results and suitable heuristic technique will be selected for the best performance of the system.
Ausman, N. E., Jr.; Simon, N. K.; Rodriguez, C. F.
Preparation for the Mariner Mars 1971 mission is reported, including an extensive training program for operations personnel during which the primary source of spacecraft data was a computer program simulating the spacecraft. The objectives of a simulation model for training purposes differed from objectives appropriate to a design or analysis model. Model subsystems were designed to provide realistic telemetry data reflecting changes due both to commands and environmental parameters affecting the spacecraft at various times during the mission. The spacecraft is modeled along two separate functional lines. Boolean operations are concentrated in the spacecraft logic model, which determines the spacecraft state or mode, while mathematical operations or algorithms are executed in computational subsystem models. Although logic parameters are interrogated as a part of each computational pass, actual logic model processing occurs only when a change-of-state input is generated by the operations organization. The program design, some of the special characteristics of each of the modeled subsystems, and how the model was used in support of mission operations training are presented.
Full Text Available In recent years the problem of safety of people is studied primarily in aspects of natural and man-made disasters, fire, health and safety in the workplace. A problem connected with the way of life of the people, in particular with the use of bus transport remains almost out of sight. In addition to the foregoing, there is another side to the issue: modern development of industry and transport is characterized by large-scale introduction of technical measures aimed at saving energy In the specified aspect theoretical dependences for evaluation of technological economic efficiency of light sources in indoor lighting system buses are grounded. This theoretical dependency will make analytical framework justification applying the respective sources of light, taking into account the hygiene requirements to illumination. The methodology of calculation of economic efficiency of lighting of bus salons is offered. Estimating parameter is justified relative objective function value costs per unit of time or distance. The greatest costs are typical for lamps with incandescent bulbs. The least is common to lamps with fluorescent lamps. Led bulbs have no significant advantage even over incandescent lamps. The reason for this is the relatively high color temperature radiation of LED lamps that requires more light levels and, consequently, the high cost of energy, as well as relatively large initial cost of these lamps.
Full Text Available Literature called beautiful if it contains the mandate, message, ideas and meanings that are useful for the readers. Short story “Bus Kota” (City Bus containing the mandate, message, ideas and meanings that are useful to the reader. The mandate will be revealed by Roland Barthes' semiotic theory in the book S/Z. Literature has its own allure and text have accrued but not due to independence because of the difference in quality. Texts merge into a unity, or restore any text not as an individual but as a form of plurality. Literature as part of a social system is an expression of the author's sense of the outpouring of public life. Literary works can express themselves in the author's view the social and cultural changes in society because of the development of information technology and rapid. Technological developments and socio-cultural information can change in society so as to affect the psychology of the people. Society must have a thickness of faith not only for themselves, but to be able to maintain equanimity in the life of a pluralistic society
Appelquist, G.; Hovander, B.; Sellden, B.; Bohm, C.
A generic CAMAC trigger processor module for fast processing of large amounts of ADC data, has been designed. This module has been realised using complex programmable gate arrays (LCAs from XILINX). The gate arrays have been connected to memories and multipliers in such a way that different gate array configurations can cover a wide range of module applications. Using the module, it is possible to construct complex trigger processors. The module uses both the fast ECL FERA bus and the CAMAC bus for inputs and outputs. The latter, however is primarily used for setup and control but may also be used for data output. Large numbers of ADCs can be served by a hierarchical arrangement of trigger processor modules, processing ADC data with pipe-line arithmetics producing the final result at the apex of the pyramid. The trigger decision will be transmitted to the data acquisition system via a logic signal while numeric results may be extracted by the CAMAC controller. The trigger processor was originally developed for the proposed neutral particle search experiment at CERN, NUMASS. There it was designed to serve as a second level trigger processor. It was required to correct all ADC raw data for efficiency and pedestal, calculate the total calorimeter energy, obtain the optimal time of flight data and calculate the particle mass. A suitable mass-cut would then deliver the trigger decision. More complex triggers were also considered. (orig.)
Schultz, Roger D.; Stobie, Iain C.
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.
Full Text Available Background: Meeting service quality standards and striving for loyalty are two critical areas which have until now been overlooked by both the passenger transport industry and academia in Pakistan therefore the study sheds useful light on an issue hitherto untouched. Therefore increased sample size will help in increasing generalizability of study. Methods: This paper is designed to study the level of loyalty at Daewoo Express Bus Service in Sargodha by measuring customer satisfaction. Researchers used a small sample of only 96 respondents (passengers and only studies customer's behavior in the service quality of Daewoo Express Bus Service however it may differ in other passenger transport services. Results and conclusions: This paper reveals that there is a positive and significant relationship between loyalty (dependant variable and price perceptions, reliability, retrieving and smoothing (independent variables. However, the study found that reliability of services is the most important dimension among other independent variables (price perceptions, smoothing, reliability, retrieving effecting customers loyalty at Daewoo Express. Paper under consideration would surely assist Daewoo`s management team to take care of the loopholes existing in the current service level and likely threats which Daewoo might face.
Appelquist, G.; Hovander, B.; Sellden, B.; Bohm, C.
A generic CAMAC based trigger processor module for fast processing of large amounts of ADC data, has been designed. This module has been realised using complex programmable gate arrays (LCAs from XILINX). The gate arrays have been connected to memories and multipliers in such a way that different gate array configurations can cover a wide range of module applications. Using this module, it is possible to construct complex trigger processors. The module uses both the fast ECL FERA bus and the CAMAC bus for inputs and outputs. The latter, however, is primarily used for set-up and control but may also be used for data output. Large numbers of ADCs can be served by a hierarchical arrangement of trigger processor modules, processing ADC data with pipe-line arithmetics producing the final result at the apex of the pyramid. The trigger decision will be transmitted to the data acquisition system via a logic signal while numeric results may be extracted by the CAMAC controller. The trigger processor was originally developed for the proposed neutral particle search experiment at CERN, NUMASS. There it was designed to serve as a second level trigger processor. It was required to correct all ADC raw data for efficiency and pedestal, calculate the total calorimeter energy, obtain the optimal time of flight data and calculate the particle mass. A suitable mass cut would then deliver the trigger decision. More complex triggers were also considered. (au)
Bögl, Michael; Doerner, Karl F; Parragh, Sophie N
In this article, we study the school bus routing and scheduling problem with transfers arising in the field of nonperiodic public transportation systems. It deals with the transportation of pupils from home to their school in the morning taking the possibility that pupils may change buses into account. Allowing transfers has several consequences. On the one hand, it allows more flexibility in the bus network structure and can, therefore, help to reduce operating costs. On the other hand, transfers have an impact on the service level: the perceived service quality is lower due to the existence of transfers; however, at the same time, user ride times may be reduced and, thus, transfers may also have a positive impact on service quality. The main objective is the minimization of the total operating costs. We develop a heuristic solution framework to solve this problem and compare it with two solution concepts that do not consider transfers. The impact of transfers on the service level in terms of time loss (or user ride time) and the number of transfers is analyzed. Our results show that allowing transfers reduces total operating costs significantly while average and maximum user ride times are comparable to solutions without transfers. © 2015 Wiley Periodicals, Inc. NETWORKS, Vol. 65(2), 180-203 2015.
The U.S. Federal Transit Administration (FTA) funds a variety of research projects that support the commercialization of zero-emission bus technology. To evaluate projects funded through these programs, FTA has enlisted the help of the National Renewable Energy Laboratory (NREL) to conduct third-party evaluations of the technologies deployed under the FTA programs. NREL works with the selected agencies to evaluate the performance of the zero-emission buses compared to baseline conventional buses in similar service. The evaluation effort will advance the knowledge base of zero-emission technologies in transit bus applications and provide 'lessons learned' to aid other fleets in incrementally introducing next generation zero-emission buses into their operations. This report provides preliminary performance evaluation results from a demonstration of three zero-emission battery electric buses at King County Metro in King County, Washington. NREL developed this preliminary results report to quickly disseminate evaluation results to stakeholders. Detailed evaluation results will be published in future reports.
Dales, Robert; Liu, Ling; Szyszkowicz, Mietek; Dalipaj, Mary; Willey, Jeff; Kulka, Ryan; Ruddy, Terrence D
Particulate air pollution is associated with cardiovascular morbidity but mechanisms are not well understood. We tested the effects on vascular reactivity of exposure to fine particulates matter mass (PM(2.5)), number of particles bus stops. Flow-mediated vasodilation (FMD) of the brachial artery was then measured by ultrasound and expressed as: (maximum artery diameter after release of a blood pressure cuff inflated above systolic pressure-baseline resting diameter)/baseline resting diameter. A 30 microg/m(3) increase in PM(2.5) exposure corresponded to a 0.48% reduction in FMD, P=0.05 representing a 5% relative change in the maximum ability to dilate. Results were consistent between the two bus stops and not sensitive to type of analysis. No significant association was found between FMD and NO(2), PM(1.0) or traffic density. PM(2.5) may reduce the capacity to vasodilate, a potential explanation for the documented association with cardiovascular morbidity.
Jamriska, Milan; Morawska, Lidia; Thomas, Steven; He, Congrong
The emission factors of a bus fleet consisting of approximately 300 diesel-powered buses were measured in a tunnel study under well-controlled conditions during a 2-d monitoring campaign in Brisbane. Particle number and mass concentration levels of submicrometer particles and PM2.5 were monitored by SMPS and DustTrak instruments at the tunnel's entrance and exit, respectively. Correlation between DustTrak and TEOM response to diesel emissions was assessed, and the DustTrak results were recalculated into TEOM equivalent data. The mean value of the number and mass emission factors was (3.11+/-2.41) x 10(14) particles km(-1) for submicrometer particles and 583+/-451 mg km(-1) for PM2.5 (DustTrak), respectively. TEOM PM2.5 equivalent emission factor was 267+/-207 mg km(-1). The results are in good agreement with the emission factors determined from steady-state dynamometer testing of 12 buses from the same Brisbane City bus fleet. The results indicate that when carefully designed, both approaches, the dynamometer and on-road studies, can provide comparable results, applicable for the assessment of the effect of traffic emissions on airborne particle pollution. A brief overview of emission factors determined from other on-road and dynamometer studies reported in the literature as well as with the regulatory values used for the vehicle emission inventory assessment is presented and compared with the results obtained in this study.
Full Text Available This paper proposes new positive feedback source coupled logic (PFSCL tristate buffers suited to bus applications. The proposed buffers use switch to attain high impedance state and modify the load or the current source section. An interesting consequence of this is overall reduction in the power consumption. The proposed tristate buffers consume half the power compared to the available switch based counterpart. The issues with available PFSCL tristate buffers based bus implementation are identified and benefits of employing the proposed tristate buffer topologies are put forward. SPICE simulation results using TSMC 180 nm CMOS technology parameters are included to support the theoretical formulations. The performance of proposed tristate buffer topologies is examined on the basis of propagation delay, output enable time, and power consumption. It is found that one of the proposed tristate buffer topology outperforms the others in terms of all the performance parameters. An examination of behavior of available and the proposed PFSCL tristate buffer topologies under parameter variations and mismatch shows a maximum variation of 14%.
The host processor for a code running within a distributed process control system is often predetermined by constraints built into the software architecture of the control system. Input/output (I/O) channels directly connected to the host processors are usually easier to access in software than channels on remote processors. It is often difficult to modernize selective parts of a control system's software while leaving the other parts unchanged. Likewise, software developed at one laboratory is often difficult to integrate into a control system developed at another laboratory. Software that runs in one machine or operating-system architecture is often unable to communicate with control-system software running on a different platform. For the Los Alamos Accelerator Control System (LAACS) we have attempted to address the above difficulties with a software communication facility which we call Channel Access. Channel Access provides a 'software bus' that allows programs to be connected through a network to I/O channels on real-time processors in a manner similar to the way in which hardware modules are integrated within a standardized hardware bus such as CAMAC or VME. We have already placed an operator interface on Channel Access and we are currently designing alarm, archiving and sequencing tools as well. Numerous application-specific programs use Channel Access. This paper describes the unique feature of this approach and its performance as an integral part of the Los Alamos Accelerator Control System. (orig.)
Pang, John Zhen Fu; Bin Othman, Nasri; Ng, Keng Meng; Monterola, Christopher
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.
Outlines common-sense tips for disciplining student bus riders that are recommended by several driver-training programs. Themes include the following: (1) Set a few clear rules for proper bus behavior; (2) be positive; and (3) establish amiable communication with the children and with the principal as well. (CJH)
Anund, A.; Ihlström, J.; Fors, C.; Kecklund, L.G.; Filtness, A.J.
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
Full Text Available As transit service performance should be considered from the transit passengers’ perspectives, it is essential to determine passengers’ perceptions of service performance and to understand the role of these perceptions in travel decisions. As the bus market share has steadily declined, the aim of this study is to explore the impact of perceptions of bus service performance on mode choice preference to increase bus ridership. To achieve this research objective, an intention survey is conducted to obtain bus passengers’ attitudes. Exploratory factor analysis and confirmatory factor analysis are used to measure passengers’ perceptions and to extract the main factors from the bus service attributes. Next, structural equation modeling is used to reveal how passengers’ perceptions vary by demographics and trip characteristics. Finally, multinomial logit modeling is used to explore the impact of perception factors on mode choice preference. The results of this study show that perceptions of the reliability and comfort of bus services have a more significant impact on passengers’ mode choice preference than perceptions of availability and safety do. The implications in terms of improving bus service reliability and comfort can increase bus ridership.
The objective of this project is to identify a representative school bus (weight and axle spacing) for load rating highway bridges. The ALDOT Bridge Rating and Load Test Section currently uses a 12.5-ton school bus (four tons on the front axle and 8....
SUMMARY Bus Rapid Transit (BRT) can be defined as “a bus-based mass transit system that delivers fast, comfortable, and cost-effective urban mobility”. It offers the opportunity to create a high-quality mass transit system at affordable costs, which is p
A practicum was designed to reduce disruptive behavior of students riding school buses in a small multicultural community. It was determined that many students were disruptive when riding the school buses, making it difficult for the bus drivers to ensure riders' safety. The practicum implemented a school bus safety education and public awareness…