VCSELs based on arrays of sub-monolayer InGaAs quantum dots

International Nuclear Information System (INIS)

Blokhin, S. A.; Maleev, N. A.; Kuz'menkov, A. G.; Shernyakov, Yu. M.; Novikov, I. I.; Gordeev, N. Yu.; Dyudelev, V. V.; Sokolovskii, G. S.; Kuchinskii, V. I.; Kulagina, M. M.; Maximov, M. V.; Ustinov, V. M.; Kovsh, A. R.; Mikhrin, S. S.; Ledentsov, N. N.

2006-01-01

Vertical-cavity surface-emitting lasers (VCSELs) with an active region based on sub-monolayer InGaAs quantum dots and doped AlGaAs/GaAs distributed Bragg reflectors were grown by MBE. VCSELs with current aperture of 3 μm in diameter demonstrate single-mode lasing in 980-nm range with the threshold current of 0.6 mA, maximum output power up to 4 mW, and external differential efficiency of 68%. Multimode VCSELs with a (10-12)-μm aperture demonstrate ultralow internal optical loss of 0.09% per pass, which compares favorably with the best results obtained in similar lasers with undoped distributed Bragg reflectors

Single-Mode VCSELs

Science.gov (United States)

Larsson, Anders; Gustavsson, Johan S.

The only active transverse mode in a truly single-mode VCSEL is the fundamental mode with a near Gaussian field distribution. A single-mode VCSEL produces a light beam of higher spectral purity, higher degree of coherence and lower divergence than a multimode VCSEL and the beam can be more precisely shaped and focused to a smaller spot. Such beam properties are required in many applications. In this chapter, after discussing applications of single-mode VCSELs, we introduce the basics of fields and modes in VCSELs and review designs implemented for single-mode emission from VCSELs in different materials and at different wavelengths. This includes VCSELs that are inherently single-mode as well as inherently multimode VCSELs where higher-order modes are suppressed by mode selective gain or loss. In each case we present the current state-of-the-art and discuss pros and cons. At the end, a specific example with experimental results is provided and, as a summary, the most promising designs based on current technologies are identified.

VCSELs in short-pulse operation for time-of-flight applications

Science.gov (United States)

Moench, Holger; Gronenborn, Stephan; Gu, Xi; Gudde, Ralph; Herper, Markus; Kolb, Johanna; Miller, Michael; Smeets, Michael; Weigl, Alexander

2018-02-01

VCSEL arrays are the ideal light source for 3D imaging applications. The narrow emission spectrum and the ability for short pulses make them superior to LEDs. Combined with fast photodiodes or special camera chips spatial information can be obtained which is needed in diverse applications like camera autofocus, indoor navigation, 3D-object recognition, augmented reality or autonomously driving vehicles. Pulse operation at the ns scale and at low duty cycle can work with significantly higher current than traditionally used for VCSELs in continuous wave operation. With reduced thermal limitations at low average heat dissipation very high currents become feasible and tens of Watts output power have been realized with small VCSEL chips. The optical emission pattern of VCSELs can be tailored to the desired field of view using beam shaping elements. Such optical elements also enable laser safe class 1 products. A detailed analysis of the complete system and the operation mode is required to calculate the maximum permitted power for a safe system. The good VCSEL properties like robustness, stability over temperature and the potential for integrated solutions open a huge potential for VCSELs in new mass applications in the consumer and automotive markets.

Free-Space Optical Interconnect Employing VCSEL Diodes

Science.gov (United States)

Simons, Rainee N.; Savich, Gregory R.; Torres, Heidi

2009-01-01

Sensor signal processing is widely used on aircraft and spacecraft. The scheme employs multiple input/output nodes for data acquisition and CPU (central processing unit) nodes for data processing. To connect 110 nodes and CPU nodes, scalable interconnections such as backplanes are desired because the number of nodes depends on requirements of each mission. An optical backplane consisting of vertical-cavity surface-emitting lasers (VCSELs), VCSEL drivers, photodetectors, and transimpedance amplifiers is the preferred approach since it can handle several hundred megabits per second data throughput.The next generation of satellite-borne systems will require transceivers and processors that can handle several Gb/s of data. Optical interconnects have been praised for both their speed and functionality with hopes that light can relieve the electrical bottleneck predicted for the near future. Optoelectronic interconnects provide a factor of ten improvement over electrical interconnects.

Recent Advances of VCSEL Photonics

Science.gov (United States)

Koyama, Fumio

2006-12-01

A vertical-cavity surface emitting laser (VCSEL) was invented 30 years ago. A lot of unique features can be expected, such as low-power consumption, wafer-level testing, small packaging capability, and so on. The market of VCSELs has been growing up rapidly in recent years, and they are now key devices in local area networks using multimode optical fibers. Also, long wavelength VCSELs are currently attracting much interest for use in single-mode fiber metropolitan area and wide area network applications. In addition, a VCSEL-based disruptive technology enables various consumer applications such as a laser mouse and laser printers. In this paper, the recent advance of VCSEL photonics will be reviewed, which include the wavelength extension of single-mode VCSELs and their wavelength integration/control. Also, this paper explores the potential and challenges for new functions of VCSELs toward optical signal processing.

High-speed highly temperature stable 980 nm VCSELs operating at 25 Gb/s at up to 85 °C for short reach optical interconnects

Science.gov (United States)

Mutig, Alex; Lott, James A.; Blokhin, Sergey A.; Moser, Philip; Wolf, Philip; Hofmann, Werner; Nadtochiy, Alexey M.; Bimberg, Dieter

2011-03-01

The progressive penetration of optical communication links into traditional copper interconnect markets greatly expands the applications of vertical cavity surface emitting lasers (VCSELs) for the next-generation of board-to-board, moduleto- module, chip-to-chip, and on-chip optical interconnects. Stability of the VCSEL parameters at high temperatures is indispensable for such applications, since these lasers typically reside directly on or near integrated circuit chips. Here we present 980 nm oxide-confined VCSELs operating error-free at bit rates up to 25 Gbit/s at temperatures as high as 85 °C without adjustment of the drive current and peak-to-peak modulation voltage. The driver design is therefore simplified and the power consumption of the driver electronics is lowered, reducing the production and operational costs. Small and large signal modulation experiments at various temperatures from 20 up to 85 °C for lasers with different oxide aperture diameters are presented in order to analyze the physical processes controlling the performance of the VCSELs. Temperature insensitive maximum -3 dB bandwidths of around 13-15 GHz for VCSELs with aperture diameters of 10 μm and corresponding parasitic cut-off frequencies exceeding 22 GHz are observed. Presented results demonstrate the suitability of our VCSELs for practical high speed and high temperature stable short-reach optical links.

Semi-automatic characterization and simulation of VCSEL devices for high speed VSR communications

Science.gov (United States)

Pellevrault, S.; Toffano, Z.; Destrez, A.; Pez, M.; Quentel, F.

2006-04-01

Very short range (VSR) high bit rate optical fiber communications are an emerging market dedicated to local area networks, digital displays or board to board interconnects within real time calculators. In this technology, a very fast way to exchange data with high noise immunity and low-cost is needed. Optical multimode graded index fibers are used here because they have electrical noise immunity and are easier to handle than monomode fibers. 850 nm VCSEL are used in VSR communications because of their low cost, direct on-wafer tests, and the possibility of manufacturing VCSEL arrays very easily compared to classical optical transceivers using edge-emitting laser diodes. Although much research has been carried out in temperature modeling on VCSEL emitters, few studies have been devoted to characterizations over a very broad range of temperatures. Nowadays, VCSEL VSR communications tend to be used in severe environments such as space, avionics and military equipments. Therefore, a simple way to characterize VCSEL emitters over a broad range of temperature is required. In this paper, we propose a complete characterization of the emitter part of 2.5 Gb/s opto-electrical transceiver modules operating from -40°C to +120°C using 850 nm VCSELs. Our method uses simple and semi-automatic measurements of a given set of chosen device parameters in order to make fast and efficient simulations.

Study of the Radiation-Hardness of VCSEL and PIN

CERN Document Server

Gan, K K; Fernando, W; Kagan, H P; Kass, R D; Lebbai, M R M; Merritt, H; Moore, J R; Nagarkar, A; Rizatdinova, F; Skubic, P L; Smith, D S; Strang, M

2009-01-01

The silicon trackers of the ATLAS experiment at the Large Hadron Collider (LHC) at CERN (Geneva) use optical links for data transmission. An upgrade of the trackers is planned for the Super LHC (SLHC), an upgraded LHC with ten times higher luminosity. We study the radiation-hardness of VCSELs (Vertical-Cavity Surface-Emitting Laser) and GaAs and silicon PINs using 24 GeV/c protons at CERN for possible application in the data transmission upgrade. The optical power of VCSEL arrays decreases significantly after the irradiation but can be partially annealed with high drive currents. The responsivities of the PIN diodes also decrease significantly after irradiation, but can be recovered by operating at higher bias voltage. This provides a simple mechanism to recover from the radiation damage.

DFB laser array driver circuit controlled by adjustable signal

Science.gov (United States)

Du, Weikang; Du, Yinchao; Guo, Yu; Li, Wei; Wang, Hao

2018-01-01

In order to achieve the intelligent controlling of DFB laser array, this paper presents the design of an intelligence and high precision numerical controlling electric circuit. The system takes MCU and FPGA as the main control chip, with compact, high-efficiency, no impact, switching protection characteristics. The output of the DFB laser array can be determined by an external adjustable signal. The system transforms the analog control model into a digital control model, which improves the performance of the driver. The system can monitor the temperature and current of DFB laser array in real time. The output precision of the current can reach ± 0.1mA, which ensures the stable and reliable operation of the DFB laser array. Such a driver can benefit the flexible usage of the DFB laser array.

VCSEL Based Coherent PONs

DEFF Research Database (Denmark)

Jensen, Jesper Bevensee; Rodes, Roberto; Caballero Jambrina, Antonio

2014-01-01

We present a review of research performed in the area of coherent access technologies employing vertical cavity surface emitting lasers (VCSELs). Experimental demonstrations of optical transmission over a passive fiber link with coherent detection using VCSEL local oscillators and directly modula...

Low power laser driver design in 28nm CMOS for on-chip and chip-to-chip optical interconnect

Science.gov (United States)

Belfiore, Guido; Szilagyi, Laszlo; Henker, Ronny; Ellinger, Frank

2015-09-01

This paper discusses the challenges and the trade-offs in the design of laser drivers for very-short distance optical communications. A prototype integrated circuit is designed and fabricated in 28 nm super-low-power CMOS technology. The power consumption of the transmitter is 17.2 mW excluding the VCSEL that in our test has a DC power consumption of 10 mW. The active area of the driver is only 0.0045 mm2. The driver can achieve an error-free (BER < 10 -12) electrical data-rate of 25 Gbit/s using a pseudo random bit sequence of 27 -1. When the driver is connected to the VCSEL module an open optical eye is reported at 15 Gbit/s. In the tested bias point the VCSEL module has a measured bandwidth of 10.7 GHz.

Proton Irradiation Effects in Oxide-Confined Vertical Cavity Surface Emitting Laser (VCSEL) Diodes

International Nuclear Information System (INIS)

Armendariz, M.G.; Barnes, C.E.; Choquette, K.D.; Guertin, S.; Hash, G.L.; Schwank, J.R.; Swift, G.M.

1999-01-01

Recent space experience has shown that the use of commercial optocouplers can be problematic in spacecraft, such as TOPEX/Poseidon, that must operate in significant radiation environments. Radiation--induced failures of these devices have been observed in space and have been further documented at similar radiation doses in the laboratory. The ubiquitous use of optocouplers in spacecraft systems for a variety of applications, such as electrical isolation, switching and power transfer, is indicative of the need for optocouplers that can withstand the space radiation environment. In addition, the distributed nature of their use implies that it is not particularly desirable to shield optocouplers for use in radiation environments. Thus, it will be important for the space community to have access to radiation hardened/tolerant optocouplers. For many microelectronic and photonic devices, it is difficult to achieve radiation hardness without sacrificing performance. However, in the case of optocouplers, one should be able to achieve both superior radiation hardness and performance for such characteristics as switching speed, current transfer ratio (CTR), minimum power usage and array power transfer, if standard light emitting diodes (LEDs), such as those in the commercial optocouplers mentioned above, are avoided, and VCSELs are employed as the emitter portion of the optocoupler. The physical configuration of VCSELs allows one to achieve parallel use of an array of devices and construct a multichannel optocoupler in the standard fashion with the emitters and detectors looking at each other. In addition, detectors similar in structure to the VCSELs can be fabricated which allows bidirectional functionality of the optocoupler. Recent discussions suggest that VCSELs will enjoy widespread applications in the telecommunications and data transfer fields

130-nm tunable grating-mirror VCSEL

DEFF Research Database (Denmark)

Chung, Il-Sug; Mørk, Jesper

2014-01-01

configuration instead of the extended cavity configuration can bring 130-nm tuning range around 1330-nm wavelength. The air-coupled cavity is known to reduce the quantum confinement factor in VCSELs, increasing threshold. In our air-coupled cavity HCG VCSEL case, the very short power penetration length...... in the HCG minimizes this reduction of the quantum confinement factor, not as significant as in the air-coupled cavity DBR VCSEL....

VCSEL Transmission at 10 Gb/s for 20 km Single Mode Fiber WDM-PON without Dispersion Compensation or Injection Locking

DEFF Research Database (Denmark)

Gibbon, Timothy Braidwood; Prince, Kamau; Pham, Tien Thang

2011-01-01

how off-center wavelength filtering of the VCSEL spectrum at an array waveguide grating can be used to mitigate the effect of chirp and the dispersion penalty. Transmission at 10Gb/s VCSEL over 23.6 km of single mode fiber is experimentally demonstrated, with a dispersion penalty of only 2.9 d......B. Simulated results are also presented which show that off-center wavelength filtering can extend the 10 Gb/s network reach from 11.7 km to 25.8 km for a 4 dB dispersion penalty. This allows for cheap and simple dispersion mitigation in next generation VCSEL based optical access networks....

Numerical methods for modeling photonic-crystal VCSELs

DEFF Research Database (Denmark)

Dems, Maciej; Chung, Il-Sug; Nyakas, Peter

2010-01-01

We show comparison of four different numerical methods for simulating Photonic-Crystal (PC) VCSELs. We present the theoretical basis behind each method and analyze the differences by studying a benchmark VCSEL structure, where the PC structure penetrates all VCSEL layers, the entire top-mirror DBR...... to the effective index method. The simulation results elucidate the strength and weaknesses of the analyzed methods; and outline the limits of applicability of the different models....

True photonic band-gap mode-control in VCSEL structures

DEFF Research Database (Denmark)

Romstad, F.; Madsen, M.; Birkedal, Dan

2003-01-01

Photonic band-gap mode confinement in novel nano-structured large area VCSEL structures is confirmed by the amplified spontaneous emission spectrum. Both guide and anti-guide VCSEL structures are experimentally characterised to verify the photonic band-gap effect.......Photonic band-gap mode confinement in novel nano-structured large area VCSEL structures is confirmed by the amplified spontaneous emission spectrum. Both guide and anti-guide VCSEL structures are experimentally characterised to verify the photonic band-gap effect....

Commercialized VCSEL components fabricated at TrueLight Corporation

Science.gov (United States)

Pan, Jin-Shan; Lin, Yung-Sen; Li, Chao-Fang A.; Chang, C. H.; Wu, Jack; Lee, Bor-Lin; Chuang, Y. H.; Tu, S. L.; Wu, Calvin; Huang, Kai-Feng

2001-05-01

TrueLight Corporation was found in 1997 and it is the pioneer of VCSEL components supplier in Taiwan. We specialize in the production and distribution of VCSEL (Vertical Cavity Surface Emitting Laser) and other high-speed PIN-detector devices and components. Our core technology is developed to meet blooming demand of fiber optic transmission. Our intention is to diverse the device application into data communication, telecommunication and industrial markets. One mission is to provide the high performance, highly reliable and low-cost VCSEL components for data communication and sensing applications. For the past three years, TrueLight Corporation has entered successfully into the Gigabit Ethernet and the Fiber Channel data communication area. In this paper, we will focus on the fabrication of VCSEL components. We will present you the evolution of implanted and oxide-confined VCSEL process, device characterization, also performance in Gigabit data communication and the most important reliability issue

VCSELs Fundamentals, Technology and Applications of Vertical-Cavity Surface-Emitting Lasers

CERN Document Server

2013-01-01

The huge progress which has been achieved in the field is covered here, in the first comprehensive monograph on vertical-cavity surface-emitting lasers (VCSELs) since eight years. Apart from chapters reviewing the research field and the laser fundamentals, there are comprehensive updates on red and blue emitting VCSELs, telecommunication VCSELs, optical transceivers, and parallel-optical links for computer interconnects. Entirely new contributions are made to the fields of vectorial three-dimensional optical modeling, single-mode VCSELs, polarization control, polarization dynamics, very-high-speed design, high-power emission, use of high-contrast gratings, GaInNAsSb long-wavelength VCSELs, optical video links, VCSELs for optical mice and sensing, as well as VCSEL-based laser printing. The book appeals to researchers, optical engineers and graduate students.

Driver-Array Based Flat-Panel Loudspeakers: Theoretical Background and Design Guidelines

Science.gov (United States)

Anderson, David Allan

This thesis relates to the simulation and design of flat-panel loudspeakers using moving-coil driver elements. A brief history of the industry is given, including a collection of products and patents from 1925 until the present, an overview of research papers, and a discussion of current products available. The mechanics of bending flat panels are developed with respect to localized driving forces, both in the frequency domain and the time domain as an impulse response. These simulations are compared to measurements on prototype panels. Additional resonant elements influence the behavior of the system: an optional ported rear enclosure and the resonant characteristics of the drivers. The governing equations for these systems are derived and solutions are implemented using equivalent mechanical circuits and numerical methods. The idea of using driver arrays to independently actuate modes of the panel is discussed at length with respect to modal addressability, modal spillover, and experimental validation. The numerical approach to determining the optimal driver placement for a given set of modes is derived and experimentally validated. An investigation of the acoustic behavior of flat panel loudspeakers is presented, using mechanical simulation results to predict the acoustic radiation. The simulations are compared to measurements and found to accurately predict important mechanical and acoustical behaviors. It is demonstrated that a driver array, with the proper biasing, is capable of creating a flat panel loudspeaker which acts more like a piston than a "diffuse radiator" flat panel loudspeaker. The techniques of "Modal Crossover Networks" are introduced, which use multi-band filters to bias the driver array differently for different frequency bands, optimized for audio reproduction. The question of how many drivers are necessary for a modal crossover network is addressed and found to be dependent on the estimated quality factor (Q) of the panel material and edge

MBE growth of VCSELs for high volume applications

Science.gov (United States)

Jäger, Roland; Riedl, Michael C.

2011-05-01

Mass market applications like laser computer mouse or optical data transmission based on vertical-cavity surface-emitting laser (VCSEL) chips need a high over all yield including epitaxy, processing, dicing, mounting and testing. One yield limitation for VCSEL structures is the emission wavelength variation of the substrate surface area leading to the fraction on laser chips which are below or above the specification limits. For most 850 nm VCSEL products a resonator wavelength variation of ±2 nm is common. This represents an average resonator thickness variation of much less than 1% which is quite challenging to be fulfilled on the entire processed wafer surface area. A high over all yield is demonstrated on MBE grown VCSEL structures.

Radiation-hard ASICs for optical data transmission in the first phase of the LHC upgrade

International Nuclear Information System (INIS)

Gan, K.K.; Buchholz, P.; Kagan, H.P.; Kass, R.D.; Moore, J.R.; Smith, D.S.; Wiese, A.; Ziolkowskic, M.

2011-01-01

We have designed two ASICs for possible applications in the optical links of a new layer of the pixel detector to be install inside the ATLAS Pixel detector for the first phase of the LHC luminosity upgrade. The ASICs include a high-speed driver for a VCSEL and a receiver/decoder to decode the signal received at a PIN diode to extract the data and clock. Both ASICs contain 4 channels for operation with a VCSEL or PIN array. The ASICs were designed using a 130 nm CMOS process to enhance the radiation-hardness. We have characterized the fabricated ASICs and the performance of the ASICs is satisfactory. The receiver/decoder properly decodes the bi-phase marked input stream with low PIN current and the driver can operate a VCSEL up to ∼5 Gb/s. The added functionalities are also successful, including redundancy to bypass a broken VCSEL or PIN channel, individual control of VCSEL current, and power-on reset circuit to set all VCSEL currents to a nominal value.

Radiation-hard ASICs for optical data transmission in the first phase of the LHC upgrade

CERN Document Server

Gan, K K; Kagan, H P; Kass, R D; Moore, J R; Smith, D S; Wiese, A; Ziolkowskic, M; 10.1088/1748-0221/5/12/C12006

2010-01-01

We have designed two ASICs for possible applications in the optical links of a new layer of the pixel detector to be install inside the ATLAS Pixel detector for the first phase of the LHC luminosity upgrade. The ASICs include a high-speed driver for the VCSEL and a receiver/decoder to decode the signal received at the PIN diode to extract the data and clock. Both ASICs contain 4 channels for operation with a VCSEL or PIN array. The ASICs were designed using a 130 nm CMOS process to enhance the radiation-hardness. We have characterized the fabricated ASICs and the performance of the ASICs is satisfactory. The receiver/decoder can properly decode the bi-phase marked input stream with low PIN current and the driver can operate a VCSEL up to ~ 5 Gb/s. The added functionalities are also successful, including redundancy to bypass a broken VCSEL or PIN channel, individual control of VCSEL current, and power-on reset circuit to set all VCSEL currents to a nominal value. The ASICs were irradiated to a dose of 46 Mrad ...

Final report on LDRD project : narrow-linewidth VCSELs for atomic microsystems.

Energy Technology Data Exchange (ETDEWEB)

Chow, Weng Wah; Geib, Kent Martin; Peake, Gregory Merwin; Serkland, Darwin Keith

2011-09-01

Vertical-cavity surface-emitting lasers (VCSELs) are well suited for emerging photonic microsystems due to their low power consumption, ease of integration with other optical components, and single frequency operation. However, the typical VCSEL linewidth of 100 MHz is approximately ten times wider than the natural linewidth of atoms used in atomic beam clocks and trapped atom research, which degrades or completely destroys performance in those systems. This report documents our efforts to reduce VCSEL linewidths below 10 MHz to meet the needs of advanced sub-Doppler atomic microsystems, such as cold-atom traps. We have investigated two complementary approaches to reduce VCSEL linewidth: (A) increasing the laser-cavity quality factor, and (B) decreasing the linewidth enhancement factor (alpha) of the optical gain medium. We have developed two new VCSEL devices that achieved increased cavity quality factors: (1) all-semiconductor extended-cavity VCSELs, and (2) micro-external-cavity surface-emitting lasers (MECSELs). These new VCSEL devices have demonstrated linewidths below 10 MHz, and linewidths below 1 MHz seem feasible with further optimization.

VCSEL-based radiation tolerant optical data links

CERN Document Server

Gregor, I M; Dowell, J; Jovanovic, P; Kootz, A; Mahout, G; Mandic, I; Weidberg, T

2000-01-01

The Large Hadron Collider (LHC) will become operational in 2005 at The European Laboratory for Particle Physics (CERN). The LHC will be the highest energy proton-proton collider in the world. One of the electronic particle detectors which will operate at the LHC is called ATLAS. The environment for electronics placed within ATLAS is extremely hostile due to the high levels of radiation and the general lack of access to components during the expected 10 year lifetime of the experiment. It is planned to use custom radiation tolerant VCSEL- based optical links to transfer data from the ATLAS inner detector to remote data acquisition electronics. A low mass, non-magnetic and radiation tolerant VCSEL packaging has been developed for the most hostile region in the center of ATLAS where the inner detector is located. The performance of the package is reported on. Qualification tests of commercial VCSELs are also described. The VCSELs were irradiated with neutrons (up to 8.10/sup 14/ n(1 MeV)/cm/sup 2/) and annealing...

100 Gb/s single VCSEL data transmission link

DEFF Research Database (Denmark)

Rodes Lopez, Roberto; Estaran Tolosa, Jose Manuel; Li, Bomin

2012-01-01

100 Gb/s optical fiber transmission link with a single 1.5 um VCSEL has been experimentally demonstrated using 4-level pulse amplitude modulation.......100 Gb/s optical fiber transmission link with a single 1.5 um VCSEL has been experimentally demonstrated using 4-level pulse amplitude modulation....

A 1550-nm all-optical VCSEL-to-VCSEL wavelength conversion of a 8.5-Gb/s data signal and transmission over a 24.7-km fibre

Science.gov (United States)

Boiyo, D. Kiboi; Isoe, G. M.; Gamatham, R. R. G.; Leitch, A. W. R.; Gibbon, T. B.

2016-02-01

For the first time, we demonstrate, VCSEL-to-VCSEL wavelength conversion within the low attenuation 1550 nm window, including transmission over fibre and bit error rate (BER) performance characterization. We experimentally demonstrate a low injection power optical wavelength conversion by injecting an optical beam from a signal carrier master vertical cavity surface-emitting laser (VCSEL) into the side-mode of the slave VCSEL. This technique solves the challenge of wavelength collisions and also provides wavelength re-use in typical wavelength division multiplexed (WDM) systems. This paper, for the first time, uses two 1550 nm VCSELs with tunability range of 3 nm for a 5-9.8 mA bias current. The master VCSEL is modulated with a non-return-to-zero (NRZ) pseudo-random binary sequence (PRBS_27-1) 8.5 Gb/s data. A data conversion penalty of 1.1 dB is realized when a 15 dBm injection beam is used. The transmission performance of the converted wavelength from the slave VCSEL is evaluated using BER measurement at a 10-9 threshold. A 0.5 dB transmission penalty of the converted wavelength data is realized in an 8.5 Gb/s transmission over 24.7 km. This work is vital for optical fibre systems that may require wavelength switching for transmission of data signals.

Temperature dependence of 1.55 μm VCSELs

Science.gov (United States)

Masum, J.; Balkan, N.; Adams, M. J.

1998-08-01

The temperature for minimum threshold carrier concentration in 1.55 μm VCSELs can be significantly lower than that at which the peak gain matches the cavity resonance. A simple model is implemented to investigate the magnitude of this temperature difference and to aid the design of VCSELs for room temperature operation.

Flip-chip bonded optoelectronic integration based on ultrathin silicon (UTSi) CMOS

Science.gov (United States)

Hong, Sunkwang; Ho, Tawei; Zhang, Liping; Sawchuk, Alexander A.

2003-06-01

We describe the design and test of flip-chip bonded optoelectronic CMOS devices based on Peregrine Semiconductor's 0.5 micron Ultra-Thin Silicon on sapphire (UTSi) technology. The UTSi process eliminates the substrate leakage that typically results in crosstalk and reduces parasitic capacitance to the substrate, providing many benefits compared to bulk silicon CMOS. The low-loss synthetic sapphire substrate is optically transparent and has a coefficient of thermal expansion suitable for flip-chip bonding of vertical cavity surface emitting lasers (VCSELs) and detectors. We have designed two different UTSi CMOS chips. One contains a flip-chip bonded 1 x 4 photodiode array, a receiver array, a double edge triggered D-flip flop-based 2047-pattern pseudo random bit stream (PRBS) generator and a quadrature-phase LC-voltage controlled oscillator (VCO). The other chip contains a flip-chip bonded 1 x 4 VCSEL array, a driver array based on high-speed low-voltage differential signals (LVDS) and a full-balanced differential LC-VCO. Each VCSEL driver and receiver has individual input and bias voltage adjustments. Each UTSi chip is mounted on different printed circuit boards (PCBs) which have holes with about 1 mm radius for optical output and input paths through the sapphire substrate. We discuss preliminary testing of these chips.

InAs quantum wires on InP substrate for VCSEL applications

OpenAIRE

Lamy , Jean-Michel; Paranthoën , Cyril; Levallois , Christophe; Nakkar , Abdulhadi; Folliot , Hervé; Dehaese , Olivier; Le Corre , Alain; Loualiche , Slimane; Castany , Olivier; Dupont , Laurent

2008-01-01

International audience; Quantum dash based vertical cavity surface emitting lasers (VCSEL) on InP substrate are presented. Single and close stacking layers were successfully grown with molecular beam epitaxy. Optimized quantum dash layers exhibit a strong polarized 1.55 µm photoluminescence along the [1-10] crystallographic axis. Continuous wave laser emission is demonstrated at room temperature for the first time on a quantum dash VCSEL structure on InP susbtrate. The quantum dash VCSEL lase...

Improvement of kink characteristic of proton-implanted VCSEL with ITO overcoating

Science.gov (United States)

Lai, Fang-I.; Chang, Ya-Hsien; Laih, Li-Hong; Kuo, Hao-chung; Wang, S. C.

2004-06-01

Proton implanted VCSEL has been demonstrated with good reliability and decent modulation speed up to 1.25 Gb/s. However, kinks in current vs light output (L-I) has been always an issue in the gain-guided proton implant VCSEL. The kink related jitter and noise performance made it difficult to meet 2.5 Gb/s (OC-48) requirement. The kinks in L-I curve can be attributed to non-uniform carrier distribution induced non-uniform gain distribution within emission area. In this paper, the effects of a Ti/ITO transparent over-coating on the proton-implanted AlGaAs/GaAs VCSELs (15um diameter aperture) are investigated. The kinks distribution in L-I characteristics from a 2 inch wafer is greatly improved compared to conventional process. These VCSELs exhibit nearly kink-free L-I output performance with threshold currents ~3 mA, and the slope efficiencies ~ 0.25 W/A. The near-field emission patterns suggest the Ti/ITO over-coating facilitates the current spreading and uniform carrier distribution of the top VCSEL contact thus enhancing the laser performance. Finally, we performed high speed modulation measurement. The eye diagram of proton-implanted VCSELs with Ti/ITO transparent over-coating operating at 2.125 Gb/s with 10mA bias and 9dB extinction ratio shows very clean eye with jitter less than 35 ps.

Radiation-hard ASICs for optical data transmission in the first phase of the LHC upgrade

International Nuclear Information System (INIS)

Gan, K K; Kagan, H P; Kass, R D; Moore, J R; Smith, D S; Buchholz, P; Wiese, A; Ziolkowskic, M

2010-01-01

We have designed two ASICs for possible applications in the optical links of a new layer of the pixel detector to be install inside the ATLAS Pixel detector for the first phase of the LHC luminosity upgrade. The ASICs include a high-speed driver for the VCSEL and a receiver/decoder to decode the signal received at the PIN diode to extract the data and clock. Both ASICs contain 4 channels for operation with a VCSEL or PIN array. The ASICs were designed using a 130 nm CMOS process to enhance the radiation-hardness. We have characterized the fabricated ASICs and the performance of the ASICs is satisfactory. The receiver/decoder can properly decode the bi-phase marked input stream with low PIN current and the driver can operate a VCSEL up to ∼ 5 Gb/s. The added functionalities are also successful, including redundancy to bypass a broken VCSEL or PIN channel, individual control of VCSEL current, and power-on reset circuit to set all VCSEL currents to a nominal value. The ASICs were irradiated to a dose of 46 Mrad with 24 GeV/c protons. The observed modest degradation is acceptable and the single event upset rate is negligible.

3D finite element simulation of optical modes in VCSELs

OpenAIRE

Rozova, M.; Pomplun, J.; Zschiedrich, L.; Schmidt, F.; Burger, S.

2011-01-01

We present a finite element method (FEM) solver for computation of optical resonance modes in VCSELs. We perform a convergence study and demonstrate that high accuracies for 3D setups can be attained on standard computers. We also demonstrate simulations of thermo-optical effects in VCSELs.

Demonstration of Raman-based, dispersion-managed VCSEL technology for fibre-to-the-hut application

Science.gov (United States)

Rotich Kipnoo, E. K.; Kiboi Boiyo, D.; Isoe, G. M.; Chabata, T. V.; Gamatham, R. R. G.; Leitch, A. W. R.; Gibbon, T. B.

2017-03-01

For the first time, we experimentally investigate the use of vertical cavity surface emitting lasers (VCSELs) in the fibre-to-the-home (FTTH) flavour for Africa, known as fibre-to-the-hut. Fibre-to-the-hut is a VCSEL based passive optical network technology designed and optimized for African continent. VCSELs have attracted attention in optical communication due to its vast advantages; low power consumption, relatively cheap costs among others. A 4.25 Gb/s uncooled VCSEL is used in a dispersion managed, Raman assisted network achieving beyond 100 km of error free transmission suited for FTTHut scenario. Energy-efficient high performance VCSEL is modulated using a 27-1 PRBS pattern and the signal transmitted on a G.655 fibre utilizing the minimum attenuation window.

All-VCSEL Transmitters With Remote Optical Injection for WDM-OFDM-PON

DEFF Research Database (Denmark)

Deng, Lei; Zhao, Ying; Pang, Xiaodan

2014-01-01

We report on a novel scheme that uses vertical cavity surface emitting lasers (VCSELs) and remote optical injection technique in the hybrid wavelength division multiplexing orthogonal frequency division multiplexing (OFDM) passive optical network. In the proposed scheme, 1.55-$\\mu{\\rm m}$ VCSELs ...

Bidirectional uncompressed HD video distribution over fiber employing VCSELs

DEFF Research Database (Denmark)

Estaran Tolosa, Jose Manuel; Vegas Olmos, Juan José; Rodes, G. A.

2012-01-01

We report on a bidirectional system in which VCSELs are simultaneously modulated with two uncompressed HD video signals. The results show a large power budget and a negligible penalty over 10 km long transmission links.......We report on a bidirectional system in which VCSELs are simultaneously modulated with two uncompressed HD video signals. The results show a large power budget and a negligible penalty over 10 km long transmission links....

Reliability and degradation of oxide VCSELs due to reaction to atmospheric water vapor

Science.gov (United States)

Dafinca, Alexandru; Weidberg, Anthony R.; McMahon, Steven J.; Grillo, Alexander A.; Farthouat, Philippe; Ziolkowski, Michael; Herrick, Robert W.

2013-03-01

850nm oxide-aperture VCSELs are susceptible to premature failure if operated while exposed to atmospheric water vapor, and not protected by hermetic packaging. The ATLAS detector in CERN's Large Hadron Collider (LHC) has had approximately 6000 channels of Parallel Optic VCSELs fielded under well-documented ambient conditions. Exact time-to-failure data has been collected on this large sample, providing for the first time actual failure data at use conditions. In addition, the same VCSELs were tested under a variety of accelerated conditions to allow us to construct a more accurate acceleration model. Failure analysis information will also be presented to show what we believe causes corrosion-related failure for such VCSELs.

Modal loss mechanism of micro-structured VCSELs studied using full vector FDTD method.

Science.gov (United States)

Jo, Du-Ho; Vu, Ngoc Hai; Kim, Jin-Tae; Hwang, In-Kag

2011-09-12

Modal properties of vertical cavity surface-emitting lasers (VCSELs) with holey structures are studied using a finite difference time domain (FDTD) method. We investigate loss behavior with respect to the variation of structural parameters, and explain the loss mechanism of VCSELs. We also propose an effective method to estimate the modal loss based on mode profiles obtained using FDTD simulation. Our results could provide an important guideline for optimization of the microstructures of high-power single-mode VCSELs.

Advanced vectorial simulation of VCSELs with nano structures invited paper

DEFF Research Database (Denmark)

Chung, Il-Sug; Mørk, Jesper

2009-01-01

The single-mode properties and design issues of three vertical-cavity surface-emitting laser (VCSEL) structures incorporating nano structures are rigorously investigated. Nano structuring enables to deliver selective pumping or loss to the fundamental mode as well as stabilizing the output...... polarization state. Comparison of three vectorial simulation methods reveals that the modal expansion method is suitable for treating the nano structured VCSEL designs....

Direct high-frequency modulation of VCSELs and applications in fibre optic RF and microwave links

International Nuclear Information System (INIS)

Larsson, Anders; Carlsson, Christina; Gustavsson, Johan; Haglund, Asa; Modh, Peter; Bengtsson, Joergen

2004-01-01

With the rapid development of wireless communication networks there is an increasing demand for efficient and cost-effective transmission and distribution of RF signals. Fibre optic RF links, employing directly modulated semiconductor lasers, provide many of the desired characteristics for such distribution systems and in the search for cost-effective solutions, the vertical cavity surface emitting laser (VCSEL) is of interest. It has therefore been the purpose of this work to investigate whether 850 nm VCSELs fulfil basic performance requirements for fibre optic RF links operating in the low-GHz range. The performance of single- and multimode oxide confined VCSELs has been compared, in order to pin-point limitations and to find the optimum design. Fibre optic RF links using VCSELs and multimode fibres have been assembled and evaluated with respect to performance characteristics of importance for wireless communication systems. We have found that optimized single-mode VCSELs provide the highest performance and that links using such VCSELs and high-bandwidth multimode fibres satisfy the requirements in a number of applications, including cellular systems for mobile communication and wireless local area networks

Half-cycle QAM modulation for VCSEL-based optical links

DEFF Research Database (Denmark)

Pham, Tien Thang; Rodes Lopez, Roberto; Jensen, Jesper Bevensee

2012-01-01

Abstract (40-Word Limit): Novel spectrally efficient half-cycle QAM modulation is experimentally demonstrated. 10 Gbps 4-QAM signal in 7.5-GHz bandwidth was successfully transmitted over 20 km SMF using an un-cooled 1.5 µm VCSEL with no equalization applied.......Abstract (40-Word Limit): Novel spectrally efficient half-cycle QAM modulation is experimentally demonstrated. 10 Gbps 4-QAM signal in 7.5-GHz bandwidth was successfully transmitted over 20 km SMF using an un-cooled 1.5 µm VCSEL with no equalization applied....

Comparison of single-/few-/multi-mode 850 nm VCSELs for optical OFDM transmission.

Science.gov (United States)

Kao, Hsuan-Yun; Tsai, Cheng-Ting; Leong, Shan-Fong; Peng, Chun-Yen; Chi, Yu-Chieh; Huang, Jian Jang; Kuo, Hao-Chung; Shih, Tien-Tsorng; Jou, Jau-Ji; Cheng, Wood-Hi; Wu, Chao-Hsin; Lin, Gong-Ru

2017-07-10

For high-speed optical OFDM transmission applications, a comprehensive comparison of the homemade multi-/few-/single-transverse mode (MM/FM/SM) vertical cavity surface emitting laser (VCSEL) chips is performed. With microwave probe, the direct encoding of pre-leveled 16-QAM OFDM data and transmission over 100-m-long OM4 multi-mode-fiber (MMF) are demonstrated for intra-datacenter applications. The MM VCSEL chip with the largest emission aperture of 11 μm reveals the highest differential quantum efficiency which provides the highest optical power of 8.67 mW but exhibits the lowest encodable bandwidth of 21 GHz. In contrast, the SM VCSEL chip fabricated with the smallest emission aperture of only 3 μm provides the highest 3-dB encoding bandwidth up to 23 GHz at a cost of slight heat accumulation. After optimization, with the trade-off set between the receiving signal-to-noise ratio (SNR) and bandwidth, the FM VCSEL chip guarantees the highest optical OFDM transmission bit rate of 96 Gbit/s under back-to-back case with its strongest throughput. Among three VCSEL chips, the SM VCSEL chip with nearly modal-dispersion free feature is treated as the best candidate for carrying the pre-leveled 16-QAM OFDM data over 100-m OM4-MMF with same material structure but exhibits different oxide-layer confined gain cross-sections with one another at 80-Gbit/s with the smallest receiving power penalty of 1.77 dB.

20 Gbit/s error free transmission with ~850 nm GaAs-based vertical cavity surface emitting lasers (VCSELs) containing InAs-GaAs submonolayer quantum dot insertions

Science.gov (United States)

Lott, J. A.; Shchukin, V. A.; Ledentsov, N. N.; Stinz, A.; Hopfer, F.; Mutig, A.; Fiol, G.; Bimberg, D.; Blokhin, S. A.; Karachinsky, L. Y.; Novikov, I. I.; Maximov, M. V.; Zakharov, N. D.; Werner, P.

2009-02-01

We report on the modeling, epitaxial growth, fabrication, and characterization of 830-845 nm vertical cavity surface emitting lasers (VCSELs) that employ InAs-GaAs quantum dot (QD) gain elements. The GaAs-based VCSELs are essentially conventional in design, grown by solid-source molecular beam epitaxy, and include top and bottom gradedheterointerface AlGaAs distributed Bragg reflectors, a single selectively-oxidized AlAs waveguiding/current funneling aperture layer, and a quasi-antiwaveguiding microcavity. The active region consists of three sheets of InAs-GaAs submonolayer insertions separated by AlGaAs matrix layers. Compared to QWs the InAs-GaAs insertions are expected to offer higher exciton-dominated modal gain and improved carrier capture and retention, thus resulting in superior temperature stability and resilience to degradation caused by operating at the larger switching currents commonly employed to increase the data rates of modern optical communication systems. We investigate the robustness and temperature performance of our QD VCSEL design by fabricating prototype devices in a high-frequency ground-sourceground contact pad configuration suitable for on-wafer probing. Arrays of VCSELs are produced with precise variations in top mesa diameter from 24 to 36 μm and oxide aperture diameter from 1 to 12 μm resulting in VCSELs that operate in full single-mode, single-mode to multi-mode, and full multi-mode regimes. The single-mode QD VCSELs have room temperature threshold currents below 0.5 mA and peak output powers near 1 mW, whereas the corresponding values for full multi-mode devices range from about 0.5 to 1.5 mA and 2.5 to 5 mW. At 20°C we observe optical transmission at 20 Gb/s through 150 m of OM3 fiber with a bit error ratio better than 10-12, thus demonstrating the great potential of our QD VCSELs for applications in next-generation short-distance optical data communications and interconnect systems.

Towards 100 Gbps over 100m MMF using a 850nm VCSEL

DEFF Research Database (Denmark)

Iglesias Olmedo, Miguel; Tatarczak, Anna; Zuo, Tianjian

2014-01-01

Employing MultiCAP signaling, successful 70.4 Gbps transmission over 100m of OM3 MMF using off-the-shelf 850 nm VCSEL with 10.1 GHz 3-dB bandwidth is experimentally demonstrated indicating the feasibility of achieving 100 Gbps with a single 25 GHz VCSEL. © 2014 OSA....

Radiation-hard ASICS for sLHC optical data transmission

International Nuclear Information System (INIS)

Gan, K.K.

2009-01-01

High-speed data transmission in a high radiation environment poses an immense challenge in the detector design. We investigate the feasibility of using optical links for the silicon trackers of the ATLAS experiment for the planned upgrade of the LHC. The planned upgrade with ten times higher collision rate will produce a similar increase in the radiation. One possibility for the optical transmission is to use VCSEL arrays operating at 850 nm to transmit optical signals while using PIN arrays to convert the optical signals into electrical signals. We have designed a prototype chip containing building blocks for future SLHC optical links using a 130 nm CMOS 8RF process. The chip contains four main blocks; a VCSEL driver optimized for operation at 640 Mb/s, a VCSEL driver optimized for 3.2 Gb/s, a PIN receiver with a clock/data recovery circuit for operation at 40, 160, and 320 Mb/s, and two clock multipliers designed to operate at 640 Mb/s. The clock multiplier is designed to produce the high speed clock to serialize the data for transmission. All circuitry was designed following test results and guidelines from CERN on radiation tolerant design for the process. We have irradiated the chips with 24 GeV protons at CERN. For the VDC, the duty cycle of the output signal and the current consumption of the LVDS receiver remained constant during the irradiation. However, we observed significant decreases in the current consumption of the VCSEL driver circuit and the output drive current. This indicated that the think oxide layout used in the VCSEL driver portion of the chip might not be as radiation-hard and the circuit had been redesigned to minimize this sensitivity. For the PIN receiver, we found that the radiation produced no significant degradation, including the single event upset rate. The upset rate decreased with larger PIN current and was higher for a chip coupled to a PIN diode as expected. For the clock multipliers, we observed that the clocks of some chips

Inertial confinement fusion driver enhancements: Final focusing systems and compact heavy-ion driver designs

International Nuclear Information System (INIS)

Bieri, R.L.

1991-01-01

Required elements of an inertial confinement fusion power plant are modeled and discussed. A detailed analysis of two critical elements of candidate drivers is done, and new component designs are proposed to increase the credibility and feasibility of each driver system. An analysis of neutron damage to the final elements of a laser focusing system is presented, and multilayer -- dielectric mirrors are shown to have damage lifetimes which axe too short to be useful in a commercial power plant. A new final-focusing system using grazing incidence metal mirrors to protect sensitive laser optics is designed and shown to be effective in extending the lifetime of the final focusing system. The reflectivities and damage limits of grazing incidence metal mirrors are examined in detail, and the required mirror sizes are shown to be compatible with the beam sizes and illumination geometries currently envisioned for laser drivers. A detailed design and analysis is also done for compact arrays of superconducting magnetic quadrupoles, which are needed in a multi-beam heavy-ion driver. The new array model is developed in more detail than some previous conceptual designs and models arrays which are more compact than arrays scaled from existing single -- quadrupole designs. The improved integrated model for compact arrays is used to compare the effects of various quadrupole array design choices on the size and cost of a heavy-ion driver. Array design choices which significantly affect the cost of a heavy-ion driver include the choice of superconducting material and the thickness of the collar used to support the winding stresses. The effect of these array design choices on driver size and cost is examined and the array model is used to estimate driver cost savings and performance improvements attainable with aggressive quadrupole array designs with high-performance superconductors

VCSELs and silicon light sources exploiting SOI grating mirrors

DEFF Research Database (Denmark)

Chung, Il-Sug; Mørk, Jesper

2012-01-01

In this talk, novel vertical-cavity laser structure consisting of a dielectric Bragg reflector, a III-V active region, and a high-index-contrast grating made in the Si layer of a silicon-on-insulator (SOI) wafer will be presented. In the Si light source version of this laser structure, the SOI...... the Bragg reflector. Numerical simulations show that both the silicon light source and the VCSEL exploiting SOI grating mirrors have superior performances, compared to existing silicon light sources and long wavelength VCSELs. These devices are highly adequate for chip-level optical interconnects as well...

High-Speed, Radiation-Tolerant Laser Drivers in 0.13 $\\mu$m CMOS Technology for HEP Applications

CERN Document Server

AUTHOR|(CDS)2073369; Moreira, Paulo; Calvo, Daniela; De Remigis, Paolo; Olantera, Lauri; Soos, Csaba; Troska, Jan; Wyllie, Ken

2014-01-01

The gigabit laser driver (GBLD) and low-power GBLD (LpGBLD) are two radiation-tolerant laser drivers designed to drive laser diodes at data rates up to 4.8 Gb/s. They have been designed in the framework of the gigabit-transceiver (GBT) and versatile-link projects to provide fast optical links capable of operation in the radiation environment of future high-luminosity high-energy physics experiments. The GBLD provides laser bias and modulation currents up to 43 mA and 24 mA, respectively. It can thus be used to drive vertical cavity surface emitting laser (VCSEL) and edge-emitting laser diodes. A pre-emphasis circuit, which can provide up to 12 mA in 70 ps pulses, has also been implemented to compensate for high external capacitive loads. The current driving capabilities of the LpGBLD are 2 times smaller that those of the GBLD as it has been optimized to drive VCSELs in order to minimize the power consumption. Both application-specific integrated circuits are designed in 0.13 m commercial complementary metal-o...

Design of 3x3 Focusing Array for Heavy Ion Driver Final Report on CRADA TC-02082-04

Energy Technology Data Exchange (ETDEWEB)

Martovetsky, N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-09-28

This memo presents a design of a 3x3 quadrupole array for HIF. It contains 3 D magnetic field computations of the array build with racetrack coils with and without different shields. It is shown that it is possible to have a low error magnetic field in the cells and shield the stray fields to acceptable levels. The array design seems to be a practical solution to any size array for future multi-beam heavy ion fusion drivers.

Modeling and characterization of VCSEL-based avionics full-duplex ethernet (AFDX) gigabit links

Science.gov (United States)

Ly, Khadijetou S.; Rissons, A.; Gambardella, E.; Bajon, D.; Mollier, J.-C.

2008-02-01

Low cost and intrinsic performances of 850 nm Vertical Cavity Surface Emitting Lasers (VCSELs) compared to Light Emitting Diodes make them very attractive for high speed and short distances data communication links through optical fibers. Weight saving and Electromagnetic Interference withstanding requirements have led to the need of a reliable solution to improve existing avionics high speed buses (e.g. AFDX) up to 1Gbps over 100m. To predict and optimize the performance of the link, the physical behavior of the VCSEL must be well understood. First, a theoretical study is performed through the rate equations adapted to VCSEL in large signal modulation. Averaged turn-on delays and oscillation effects are analytically computed and analyzed for different values of the on- and off state currents. This will affect the eye pattern, timing jitter and Bit Error Rate (BER) of the signal that must remain within IEEE 802.3 standard limits. In particular, the off-state current is minimized below the threshold to allow the highest possible Extinction Ratio. At this level, the spontaneous emission is dominating and leads to significant turn-on delay, turn-on jitter and bit pattern effects. Also, the transverse multimode behavior of VCSELs, caused by Spatial Hole Burning leads to some dispersion in the fiber and degradation of BER. VCSEL to Multimode Fiber coupling model is provided for prediction and optimization of modal dispersion. Lastly, turn-on delay measurements are performed on a real mock-up and results are compared with calculations.

Amplitude Noise Suppression and Orthogonal Multiplexing Using Injection-Locked Single-Mode VCSEL

DEFF Research Database (Denmark)

Lyubopytov, Vladimir; von Lerber, Tuomo; Lassas, Matti

2017-01-01

We experimentally demonstrate BER reduction and orthogonal modulation using an injection locked single-mode VCSEL. It allows us suppressing an amplitude noise of optical signal and/or double the capacity of an information channel.......We experimentally demonstrate BER reduction and orthogonal modulation using an injection locked single-mode VCSEL. It allows us suppressing an amplitude noise of optical signal and/or double the capacity of an information channel....

Real time 1.55 μm VCSEL-based coherent detection link

DEFF Research Database (Denmark)

Rodes Lopez, Roberto; Parekh, D.; Jensen, Jesper Bevensee

2012-01-01

This paper presents an experimental demonstration of VCSEL-based PON with simplified real-time coherent receiver at 2.5 Gbps. Receiver sensitivity of −37 dBm is achieved proving splitting ratio up to 2048 after 17 km fiber transmission.......This paper presents an experimental demonstration of VCSEL-based PON with simplified real-time coherent receiver at 2.5 Gbps. Receiver sensitivity of −37 dBm is achieved proving splitting ratio up to 2048 after 17 km fiber transmission....

Study on differences between high contrast grating reflectors for TM and TE polarizations and their impact on VCSEL designs

DEFF Research Database (Denmark)

Chung, Il-Sug

2015-01-01

-refractive-index media surrounding the HCG. This enables to achieve a very short effective cavity length for VCSELs, which is essential for ultrahigh speed VCSELs and MEMS-tunable VCSELs. The obtained understandings on polarization dependences will be able to serve as important design guidelines for various HCG...

Compliant heterogeneous assemblies of micro-VCSELs as a new materials platform for integrated optoelectronics

Science.gov (United States)

Kang, Dongseok; Lee, Sung-Min; Kwong, Anthony; Yoon, Jongseung

2015-03-01

Despite many unique advantages, vertical cavity surface emitting lasers (VCSELs) have been available mostly on rigid, planar wafers over restricted areas, thereby limiting their usage for applications that can benefit from large-scale, programmable assemblies, hybrid integration with dissimilar materials and devices, or mechanically flexible constructions. Here, materials design and fabrication strategies that address these limitations of conventional VCSELs are presented. Specialized design of epitaxial materials and etching processes, together with printing-based deterministic assemblies and substrate thermal engineering, enabled defect-free release of microscale VCSELs and their device- and circuit-level implementation on non-native, flexible substrates with performance comparable to devices on the growth substrate.

Design of readout drivers for ATLAS pixel detectors using field programmable gate arrays

CERN Document Server

Sivasubramaniyan, Sriram

Microstrip detectors are an integral patt of high energy physics research . Special protocols are used to transmit the data from these detectors . To readout the data from such detectors specialized instrumentation have to be designed . To achieve this task, creative and innovative high speed algorithms were designed simulated and implemented in Field Programmable gate arrays, using CAD/CAE tools. The simulation results indicated that these algorithms would be able to perform all the required tasks quickly and efficiently. This thesis describes the design of data acquisition system called the Readout Drivers (ROD) . It focuses on the ROD data path for ATLAS Pixel detectors. The data path will be an integrated part of Readout Drivers setup to decode the data from the silicon micro strip detectors and pixel detectors. This research also includes the design of Readout Driver controller. This Module is used to control the operation of the ROD. This module is responsible for the operation of the Pixel decoders bas...

Room temperature continuous wave mid-infrared VCSEL operating at 3.35 μm

Science.gov (United States)

Jayaraman, V.; Segal, S.; Lascola, K.; Burgner, C.; Towner, F.; Cazabat, A.; Cole, G. D.; Follman, D.; Heu, P.; Deutsch, C.

2018-02-01

Tunable vertical cavity surface emitting lasers (VCSELs) offer a potentially low cost tunable optical source in the 3-5 μm range that will enable commercial spectroscopic sensing of numerous environmentally and industrially important gases including methane, ethane, nitrous oxide, and carbon monoxide. Thus far, achieving room temperature continuous wave (RTCW) VCSEL operation at wavelengths beyond 3 μm has remained an elusive goal. In this paper, we introduce a new device structure that has enabled RTCW VCSEL operation near the methane absorption lines at 3.35 μm. This device structure employs two GaAs/AlGaAs mirrors wafer-bonded to an optically pumped active region comprising compressively strained type-I InGaAsSb quantum wells grown on a GaSb substrate. This substrate is removed in processing, as is one of the GaAs mirror substrates. The VCSEL structure is optically pumped at room temperature with a CW 1550 nm laser through the GaAs substrate, while the emitted 3.3 μm light is captured out of the top of the device. Power and spectrum shape measured as a function of pump power exhibit clear threshold behavior and robust singlemode spectra.

Optimization of VCSELs for Self-Mixing Sensing

DEFF Research Database (Denmark)

Larsson, David; Yvind, Kresten; Chung, Il-Sug

2010-01-01

We have simulated the variations in optical output power from a vertical-cavity surface-emitting laser (VCSEL) subject to self-mixing feedback, which is very important for applications in sensing. In order to maximize the self-mixing signal for a given feedback we have optimized the epitaxial...

Wavelength tunable MEMS VCSELs for OCT imaging

DEFF Research Database (Denmark)

Sahoo, Hitesh Kumar; Ansbæk, Thor; Ottaviano, Luisa

2018-01-01

MEMS VCSELs are one of the most promising swept source (SS) lasers for optical coherence tomography (OCT) and one of the best candidates for future integration with endoscopes, surgical probes and achieving an integrated OCT system. However, the current MEMS-based SS are processed on the III...

All-VCSEL based digital coherent detection link for multi Gbit/s WDM passive optical networks

DEFF Research Database (Denmark)

Rodes Lopez, Roberto; Jensen, Jesper Bevensee; Zibar, Darko

2010-01-01

with record receiver sensitivity of -36 dBm after transmission over 40 km standard single mode fiber. Digital signal processing compensates for frequency offset between the transmitter and the local oscillator VCSELs, and for chromatic dispersion. This system allows for uncooled VCSEL operation and fully...

Study on VCSEL laser heating chip in nuclear magnetic resonance gyroscope

Science.gov (United States)

Liang, Xiaoyang; Zhou, Binquan; Wu, Wenfeng; Jia, Yuchen; Wang, Jing

2017-10-01

In recent years, atomic gyroscope has become an important direction of inertial navigation. Nuclear magnetic resonance gyroscope has a stronger advantage in the miniaturization of the size. In atomic gyroscope, the lasers are indispensable devices which has an important effect on the improvement of the gyroscope performance. The frequency stability of the VCSEL lasers requires high precision control of temperature. However, the heating current of the laser will definitely bring in the magnetic field, and the sensitive device, alkali vapor cell, is very sensitive to the magnetic field, so that the metal pattern of the heating chip should be designed ingeniously to eliminate the magnetic field introduced by the heating current. In this paper, a heating chip was fabricated by MEMS process, i.e. depositing platinum on semiconductor substrates. Platinum has long been considered as a good resistance material used for measuring temperature The VCSEL laser chip is fixed in the center of the heating chip. The thermometer resistor measures the temperature of the heating chip, which can be considered as the same temperature of the VCSEL laser chip, by turning the temperature signal into voltage signal. The FPGA chip is used as a micro controller, and combined with PID control algorithm constitute a closed loop control circuit. The voltage applied to the heating resistor wire is modified to achieve the temperature control of the VCSEL laser. In this way, the laser frequency can be controlled stably and easily. Ultimately, the temperature stability can be achieved better than 100mK.

VCSEL sources for optical fiber-wireless composite data links at 60GHz

DEFF Research Database (Denmark)

Vegas Olmos, Juan José; Pang, Xiaodan; Lebedev, Alexander

2013-01-01

This paper presents a performance assessment of 60-GHz mm-wave signal generation using photonic upconversion employing a VCSEL as source. The system reaches 10−9 BER over a variety of optical fibers for data rates of 1.25-Gbit/s.......This paper presents a performance assessment of 60-GHz mm-wave signal generation using photonic upconversion employing a VCSEL as source. The system reaches 10−9 BER over a variety of optical fibers for data rates of 1.25-Gbit/s....

Optical Characterizations of VCSEL for Emission at 850 nm with Al Oxide Confinement Layers

Science.gov (United States)

Mokhtari, Merwan; Pagnod-Rossiaux, Philippe; Laruelle, Francois; Landesman, Jean-Pierre; Moreac, Alain; Levallois, Christophe; Cassidy, Daniel T.

2018-03-01

In-plane micro-photoluminescence (μ-PL) and micro-reflectivity measurements have been performed at room temperature by optical excitation perpendicular to the surface of two different structures: a complete vertical surface-emitting laser (VCSEL) structure and a VCSEL without the upper p-type distributed Bragg reflector (P-DBR). The two structures were both laterally oxidized and measurements were made on the top of oxidized and unoxidized regions. We show that, since the photoluminescence (PL) spectra consist of the cumulative effect of InGaAs/AlGaAs multi-quantum wells (MQWs) luminescence and interferences in the DBR, the presence or not of the P-DBR and oxide layers can significantly modify the spectrum. μ-PL mapping performed on full VCSEL structures clearly shows oxidized and unoxidized regions that are not resolved with visible light optical microscopy. Finally, preliminary measurements of the degree of polarization (DOP) of the PL have been made on a complete VCSEL structure before and after an oxidation process. We obtain an image of DOP measured by polarization-resolved μ-PL. These measurements allow us to evaluate the main components of strain.

Reconfigurable high-speed optical fibre networks: Optical wavelength conversion and switching using VCSELs to eliminate channel collisions

Science.gov (United States)

Boiyo, Duncan Kiboi; Chabata, T. V.; Kipnoo, E. K. Rotich; Gamatham, R. R. G.; Leitch, A. W. R.; Gibbon, T. B.

2017-01-01

We experimentally provide an alternative solution to channel collisions through up-wavelength conversion and switching by using vertical cavity surface-emitting lasers (VCSELs). This has been achieved by utilizing purely optical wavelength conversion on VCSELs at the low attenuation, 1550 nm transmission window. The corresponding transmission and bit error-rate (BER) performance evaluation is also presented. In this paper, two 1550 nm VCSELs with 50-150 GHz channel spacing are modulated with a 10 Gb/s NRZ PRBS 27-1 data and their interferences investigated. A channel interference penalty range of 0.15-1.63 dB is incurred for 150-50 GHz channel spacing without transmission. To avoid channel collisions and to minimize high interference penalties, the transmitting VCSEL with data is injected into the side-mode of a slave VCSEL to obtain a new up converted wavelength. A 16 dB extinction ratio of the incoming wavelength is achieved when a 15 dBm transmitting beam is injected into the side-mode of a -4.5 dBm slave VCSEL. At 8.5 Gb/s, a 1.1 dB conversion and a 0.5 dB transmission penalties are realized when the converted wavelength is transmitted over a 24.7 km G.655 fibre. This work offers a low-cost, effective wavelength conversion and channel switching to reduce channel collision probability by reconfiguring channels at the node of networks.

Real time algorithm temperature compensation in tunable laser / VCSEL based WDM-PON system

DEFF Research Database (Denmark)

Iglesias Olmedo, Miguel; Rodes Lopez, Roberto; Pham, Tien Thang

2012-01-01

We report on a real time experimental validation of a centralized algorithm for temperature compensation of tunable laser/VCSEL at ONU and OLT, respectively. Locking to a chosen WDM channel is shown for temperature changes over 40°C.......We report on a real time experimental validation of a centralized algorithm for temperature compensation of tunable laser/VCSEL at ONU and OLT, respectively. Locking to a chosen WDM channel is shown for temperature changes over 40°C....

Injection-locked single-mode VCSEL for orthogonal multiplexing and amplitude noise suppression

DEFF Research Database (Denmark)

Chipouline, Arkadi; Lyubopytov, Vladimir S.; Malekizandi, Mohammadreza

2017-01-01

It has been shown earlier, that the injection locked semiconductor lasers enable effective amplitude noise suppression [1] and makes possible an extra level of signal multiplexing-orthogonal modulation [2], where DPSK and ASK NRZ channels propagate at the same wavelength [3]. In our work we use...... an injection-locked 1550 nm VCSEL as a slave laser providing separation of amplitude and phase modulations, carrying independent information flows. To validate the possibility of phase modulation extraction by an injection-locked VCSEL, an experimental setup shown in Fig. 1 has been built....

107.5 Gb/s 850 nm multi- and single-mode VCSEL transmission over 10 and 100 m of multi-mode fiber

DEFF Research Database (Denmark)

Puerta Ramírez, Rafael; Agustin, M.; Chorchos, L.

2016-01-01

First time successful 107.5 Gb/s MultiCAP 850 nm OM4 MMF transmissions over 10 m with multi-mode VCSEL and up to 100 m with single-mode VCSEL are demonstrated, with BER below 7% overhead FEC limit measured for each case.......First time successful 107.5 Gb/s MultiCAP 850 nm OM4 MMF transmissions over 10 m with multi-mode VCSEL and up to 100 m with single-mode VCSEL are demonstrated, with BER below 7% overhead FEC limit measured for each case....

Transverse mode control in proton-implanted and oxide-confined VCSELs via patterned dielectric anti-phase filters

Science.gov (United States)

Kesler, Benjamin; O'Brien, Thomas; Dallesasse, John M.

2017-02-01

A novel method for controlling the transverse lasing modes in both proton implanted and oxide-confined vertical- cavity surface-emitting lasers (VCSELs) with a multi-layer, patterned, dielectric anti-phase (DAP) filter is pre- sented. Using a simple photolithographic liftoff process, dielectric layers are deposited and patterned on individual VCSELs to modify (increase or decrease) the mirror reflectivity across the emission aperture via anti-phase reflections, creating spatially-dependent threshold material gain. The shape of the dielectric pattern can be tailored to overlap with specific transverse VCSEL modes or subsets of transverse modes to either facilitate or inhibit lasing by decreasing or increasing, respectively, the threshold modal gain. A silicon dioxide (SiO2) and titanium dioxide (TiO2) anti-phase filter is used to achieve a single-fundamental-mode, continuous-wave output power greater than 4.0 mW in an oxide-confined VCSEL at a lasing wavelength of 850 nm. A filter consisting of SiO2 and TiO2 is used to facilitate injection-current-insensitive fundamental mode and lower order mode lasing in proton implanted VCSELs at a lasing wavelength of 850 nm. Higher refractive index dielectric materials such as amorphous silicon (a-Si) can be used to increase the effectiveness of the anti-phase filter on proton implanted devices by reducing the threshold modal gain of any spatially overlapping modes. This additive, non-destructive method allows for mode selection at any lasing wavelength and for any VCSEL layer structure without the need for semiconductor etching or epitaxial regrowth. It also offers the capability of designing a filter based upon available optical coating materials.

Energy-efficient VCSEL-based multiGigabit IR-UWB over Fiber with Airlink Transmission System

DEFF Research Database (Denmark)

Rodes Lopez, Roberto; Pham, Tien Thang; Jensen, Jesper Bevensee

2010-01-01

We propose VCSEL based impulse-radio ultrawideband technology for energy efficient high-speed wireless networks; with full passive signal distribution, from the central office to the home with high-speed wireless connection to the final user.......We propose VCSEL based impulse-radio ultrawideband technology for energy efficient high-speed wireless networks; with full passive signal distribution, from the central office to the home with high-speed wireless connection to the final user....

Vcsel structure

DEFF Research Database (Denmark)

2015-01-01

.5, and wherein an index of refraction of low-index sections of the grating structure is less than 2. The core grating region defines a projection in a direction normal to the grating layer. The grating reflector further comprises a cap layer abutting the grating layer, and an index of refraction of the cap layer...... within the projection of the core grating region onto the cap layer is at least 2.5, and within the projection of the core grating region, the cap layer is abutted by a first solid dielectric low-index layer, an index of refraction of the first low-index layer or air being less than 2; and within...... the projection of the core grating region, the grating layer is also abutted by a second low-index layer and/or by air, an index of refraction of the second low-index layer or air being less than 2. The VCSEL structure furthermore comprises a first reflector and an active region for providing a cavity...

Modal gain and confinement factors in top- and bottom-emitting photonic-crystal VCSEL

International Nuclear Information System (INIS)

Czyszanowski, T; Thienpont, H; Panajotov, K; Dems, M

2008-01-01

We investigate the modal characteristics of a phosphide photonic-crystal vertical-cavity surface-emitting diode laser (VCSEL) by using the three-dimensional, full vectorial plane wave admittance method. A single-defect, photonic crystal is defined as a regular, hexagonal net of holes with varying depths. The modal gain and confinement factors are compared for two VCSEL structures: with emission either through the DBR with the photonic crystal or through the DBR free of photonic crystal. Significant improvement in the beam quality is demonstrated for the second design

Optical interconnects based on VCSELs and low-loss silicon photonics

Science.gov (United States)

Aalto, Timo; Harjanne, Mikko; Karppinen, Mikko; Cherchi, Matteo; Sitomaniemi, Aila; Ollila, Jyrki; Malacarne, Antonio; Neumeyr, Christian

2018-02-01

Silicon photonics with micron-scale Si waveguides offers most of the benefits of submicron SOI technology while avoiding most of its limitations. In particular, thick silicon-on-insulator (SOI) waveguides offer 0.1 dB/cm propagation loss, polarization independency, broadband single-mode (SM) operation from 1.2 to >4 µm wavelength and ability to transmit high optical powers (>1 W). Here we describe the feasibility of Thick-SOI technology for advanced optical interconnects. With 12 μm SOI waveguides we demonstrate efficient coupling between standard single-mode fibers, vertical-cavity surface-emitting lasers (VCSELs) and photodetectors (PDs), as well as wavelength multiplexing in small footprint. Discrete VCSELs and PDs already support 28 Gb/s on-off keying (OOK), which shows a path towards 50-100 Gb/s bandwidth per wavelength by using more advanced modulation formats like PAM4. Directly modulated VCSELs enable very power-efficient optical interconnects for up to 40 km distance. Furthermore, with 3 μm SOI waveguides we demonstrate extremely dense and low-loss integration of numerous optical functions, such as multiplexers, filters, switches and delay lines. Also polarization independent and athermal operation is demonstrated. The latter is achieved by using short polymer waveguides to compensate for the thermo-optic effect in silicon. New concepts for isolator integration and polarization rotation are also explained.

Grüne oberflächenemittierende Halbleiterlaser (VCSEL) auf Basis von II-VI-Verbindungen

OpenAIRE

Kruse, Carsten

2004-01-01

Semiconductor-based laser diodes represent a key technology, which is used e.g. for optical data storage, data transmission and metrology purposes. However, the usual edge-emitting device design has some drawbacks concerning the properties of the emitted laser beam. This can be overcome by a more sophisticated approach called vertical-cavity surface emitting laser (VCSEL). The aim of the research within this thesis was the realization of a green fully-epitaxial VCSEL based on the II-VI materi...

8-dimensional lattice optimized formats in 25-GBaud/s VCSEL based IM/DD optical interconnections

DEFF Research Database (Denmark)

Lu, Xiaofeng; Tafur Monroy, Idelfonso

2015-01-01

Temporally combined 4- and 8-dimensional lattice grids optimized modulation formats for VCSEL based IM/DD short-reach optical inter-connections has been proposed and investigated numerically together with its conventional counterpart PAM-4. © 2015 OSA.......Temporally combined 4- and 8-dimensional lattice grids optimized modulation formats for VCSEL based IM/DD short-reach optical inter-connections has been proposed and investigated numerically together with its conventional counterpart PAM-4. © 2015 OSA....

Full C-band Tunable MEMS-VCSEL for Next Generation G.metro Mobile Front- and Backhauling

DEFF Research Database (Denmark)

Wagner, Christoph; Zou, Shihuan Jim; Ortsiefer, Markus

2017-01-01

We report full C-band tunable, 10 Gbit/s capability, directly modulated MEMS-VCSEL for next generation converged mobile fronthaul and backhaul applications. Bit error rates below 10(-9) were achieved over up to 40 km SSMF.......We report full C-band tunable, 10 Gbit/s capability, directly modulated MEMS-VCSEL for next generation converged mobile fronthaul and backhaul applications. Bit error rates below 10(-9) were achieved over up to 40 km SSMF....

Performance Analysis of Digital loudspeaker Arrays

DEFF Research Database (Denmark)

Pedersen, Bo Rohde; Kontomichos, Fotios; Mourjopoulos, John

2008-01-01

An analysis of digital loudspeaker arrays shows that the ways in which bits are mapped to the drivers influence the quality of the audio result. Specifically, a "bit-summed" rather than the traditional "bit-mapped" strategy greatly reduces the number of times drivers make binary transitions per...... period of the input frequency. Detailed simulations compare the results for a 32-loudspeaker array with a similar configuration with analog excitation of the drivers. Ideally, drivers in digital arrays should be very small and span a small area, but that sets limits on the low-frequency response...

Characterization of InAs quantum wires on (001)InP: toward the realization of VCSEL structures with a stabilized polarization

Energy Technology Data Exchange (ETDEWEB)

Lamy, J.M.; Levallois, C.; Nakhar, A.; Caroff, P.; Paranthoen, C.; Piron, R.; Le Corre, A.; Loualiche, S. [UMR C6082 FOTON - INSA de Rennes, 20 Avenue des Buttes de Coesmes, 35043 Rennes (France); Ramdane, A. [Laboratoire de Photonique et Nanostructures, CNRS UPR20, Route de Nozay, 91460 Marcoussis (France)

2007-06-15

We propose a new type of long-wavelength vertical cavity surface emitting laser (VCSEL) which consists of quantum wires (QWires) layers of InAs/InGaAsP grown on InP(001) and dielectrics Bragg mirrors, in order to control the in plane polarization of output power. QWires and quantum wells growth are performed by molecular beam epitaxy. QWires present a strong photoluminescence dependence to the polarization in contrast to the quantum wells, a polarization rate of 33% is measured. The optically pumped VCSEL is fabricated by metallic bonding, which allows the deposition of two dielectrics Bragg mirrors. The VCSEL with an active region based on InGaAs/InGaAsP quantum wells exhibits a lasing emission at 1.578 {mu}m at room temperature under continuous wave operation. The VCSEL with an active region based on quantum wires shows a luminescence at 1.53 {mu}m strongly polarized along the direction [1 anti 10] which is promising for the stabilization of in plane polarization of VCSEL emission. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Characterization of InAs quantum wires on (001)InP: toward the realization of VCSEL structures with a stabilized polarization

International Nuclear Information System (INIS)

Lamy, J.M.; Levallois, C.; Nakhar, A.; Caroff, P.; Paranthoen, C.; Piron, R.; Le Corre, A.; Loualiche, S.; Ramdane, A.

2007-01-01

We propose a new type of long-wavelength vertical cavity surface emitting laser (VCSEL) which consists of quantum wires (QWires) layers of InAs/InGaAsP grown on InP(001) and dielectrics Bragg mirrors, in order to control the in plane polarization of output power. QWires and quantum wells growth are performed by molecular beam epitaxy. QWires present a strong photoluminescence dependence to the polarization in contrast to the quantum wells, a polarization rate of 33% is measured. The optically pumped VCSEL is fabricated by metallic bonding, which allows the deposition of two dielectrics Bragg mirrors. The VCSEL with an active region based on InGaAs/InGaAsP quantum wells exhibits a lasing emission at 1.578 μm at room temperature under continuous wave operation. The VCSEL with an active region based on quantum wires shows a luminescence at 1.53 μm strongly polarized along the direction [1 anti 10] which is promising for the stabilization of in plane polarization of VCSEL emission. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Calibration and Field Deployment of the NSF G-V VCSEL Hygrometer

Science.gov (United States)

DiGangi, J. P.; O'Brien, A.; Diao, M.; Hamm, C.; Zhang, Q.; Beaton, S. P.; Zondlo, M. A.

2012-12-01

Cloud formation and dynamics have a significant influence on the Earth's radiative forcing budget, which illustrates the importance of clouds with respect to global climate. Therefore, an accurate understanding of the microscale processes dictating cloud formation is crucial for accurate computer modeling of global climate change. A critical tool for understanding these processes from an airborne platform is an instrument capable of measuring water vapor with both high accuracy and time, thus spatial, resolution. Our work focuses on an open-path, compact, vertical-cavity surface-emitting laser (VCSEL) absorption-based hygrometer, capable of 25 Hz temporal resolution, deployed on the NSF/NCAR Gulfstream-V aircraft platform. The open path nature of our instrument also helps to minimize sampling artifacts. We will discuss our efforts toward achieving within 5% accuracy over 5 orders of magnitude of water vapor concentrations. This involves an intercomparison of five independent calibration methods: ice surface saturators using an oil temperature bath, solvent slush baths (e.g. chloroform/LN2, water/ice), a research-grade frost point hygrometer, static pressure experiments, and Pt catalyzed hydrogen gas. This wide variety of available tools allows us to accurately constrain the calibrant water vapor concentrations both before and after the VCSEL hygrometer sampling chamber. For example, the mixing ratio as measured by research-grade frost point hygrometer after the VCSEL hygrometer agreed within 2% of the mixing ration expected from the water/ice bubbler source before the VCSEL over the temperature range -50°C to 20°C. Finally, due to the compact nature of our instrument, we are able to perform these calibrations simultaneously at the same temperatures (-80°C to 30°C) and pressures (150 mbar to 760 mbar) as sampled ambient air during a flight. This higher accuracy can significantly influence the science utilizing this data, which we will illustrate using

Proton irradiation effects in oxide-confined vertical cavity surface emitting laser (VCSEL) diodes

International Nuclear Information System (INIS)

Barnes, C.E.; Swift, G.M.; Guertin, S.; Schwank, J.R.; Armendariz, M.G.; Hash, G.L.; Choquette, K.D.

1999-01-01

Vertical cavity surface emitting laser (VCSEL) diodes are employed as the emitter portion of opto-couplers that are used in space applications. Proton irradiation studies on VCSELs were performed at the Indiana University cyclotron facility. The beam energy was set at 192 MeV, the beam current was 200 nA that is equivalent to a flux of approximately 1*10 11 protons/cm 2 .s. We conclude that the oxide confined VCSELs examined in this study show more than sufficient radiation hardness for nearly all space applications. The observed proton-induced decreases in light output and the corresponding increases in laser threshold current can be explained in terms of proton-induced displacement damage which introduces non-radiative recombination centers in the active region of the lasers and causes a decrease in laser efficiency. These radiation effects accentuate the detrimental thermal effects observed at high currents. We also note that forward bias annealing is effective in these devices in producing at least partial recovery of the light output, and that this may be a viable hardness assurance technique during a flight mission. (A.C.)

Optical power of VCSELs stabilized to 35 ppm/°C without a TEC

Science.gov (United States)

Downing, John

2015-03-01

This paper reports a method and system comprising a light source, an electronic method, and a calibration procedure for stabilizing the optical power of vertical-cavity surface-emitting lasers (VCSELs) and laser diodes (LDs) without the use thermoelectric coolers (TECs). The system eliminates the needs for custom interference coatings, polarization adjustments, and the exact alignment required by the optical method reported in 2013 [1]. It can precisely compensate for the effects of temperature and wavelength drift on photodiode responsivity as well as changes in VCSEL beam quality and polarization angle over a 50°C temperature range. Data obtained from light sources built with single-mode polarization-locked VCSELs demonstrate that 30 ppm/°C stability can be readily obtained. The system has advantages over TECstabilized laser modules that include: 1) 90% lower relative RMS optical power and temperature sensitivity, 2) a five-fold enhancement of wall-plug efficiency, 3) less component testing and sorting, 4) lower manufacturing costs, and 5) automated calibration in batches at time of manufacture is practical. The system is ideally suited for battery-powered environmental and in-home medical monitoring applications.

1060-nm Tunable Monolithic High Index Contrast Subwavelength Grating VCSEL

DEFF Research Database (Denmark)

Ansbæk, Thor; Chung, Il-Sug; Semenova, Elizaveta

2013-01-01

We present the first tunable vertical-cavity surface-emitting laser (VCSEL) where the top distributed Bragg reflector has been completely substituted by an air-cladded high-index-contrast subwavelength grating (HCG) mirror. In this way, an extended cavity design can be realized by reducing...

An iterative model for the steady state current distribution in oxide-confined vertical-cavity surface-emitting lasers (VCSELs)

Science.gov (United States)

Chuang, Hsueh-Hua

The purpose of this dissertation is to develop an iterative model for the analysis of the current distribution in vertical-cavity surface-emitting lasers (VCSELs) using a circuit network modeling approach. This iterative model divides the VCSEL structure into numerous annular elements and uses a circuit network consisting of resistors and diodes. The measured sheet resistance of the p-distributed Bragg reflector (DBR), the measured sheet resistance of the layers under the oxide layer, and two empirical adjustable parameters are used as inputs to the iterative model to determine the resistance of each resistor. The two empirical values are related to the anisotropy of the resistivity of the p-DBR structure. The spontaneous current, stimulated current, and surface recombination current are accounted for by the diodes. The lateral carrier transport in the quantum well region is analyzed using drift and diffusion currents. The optical gain is calculated as a function of wavelength and carrier density from fundamental principles. The predicted threshold current densities for these VCSELs match the experimentally measured current densities over the wavelength range of 0.83 mum to 0.86 mum with an error of less than 5%. This model includes the effects of the resistance of the p-DBR mirrors, the oxide current-confining layer and spatial hole burning. Our model shows that higher sheet resistance under the oxide layer reduces the threshold current, but also reduces the current range over which single transverse mode operation occurs. The spatial hole burning profile depends on the lateral drift and diffusion of carriers in the quantum wells but is dominated by the voltage drop across the p-DBR region. To my knowledge, for the first time, the drift current and the diffusion current are treated separately. Previous work uses an ambipolar approach, which underestimates the total charge transferred in the quantum well region, especially under the oxide region. However, the total

Coherent Detection for 1550 nm, 5 Gbit/s VCSEL Based 40 km Bidirectional PON Transmission

DEFF Research Database (Denmark)

Jensen, Jesper Bevensee; Rodes Lopez, Roberto; Zibar, Darko

2011-01-01

Coherent detection of directly modulated 1550nm VCSELs in 5Gbit/s bidirectional 40km SSMF PON-links is presented. Receiver sensitivity of –37.3dBm after transmission is achieved with 30dB system margin, corresponding to 1:1024 passive powersplitting.......Coherent detection of directly modulated 1550nm VCSELs in 5Gbit/s bidirectional 40km SSMF PON-links is presented. Receiver sensitivity of –37.3dBm after transmission is achieved with 30dB system margin, corresponding to 1:1024 passive powersplitting....

Comparing 52 Gbps Duobinary and 4-PAM Transmission Over 100m OM-3 Fiber With 25GHz Class VCSELs

DEFF Research Database (Denmark)

Suhr, Lau Frejstrup; Lyubomirsky, Ilya; Daghighian, Henry M.

This paper compares VCSEL based transmission of 52 Gbps duobinary-NRZ and 4-PAM over 100m OM-3 fiber employing a linear equalizer in the receiver.......This paper compares VCSEL based transmission of 52 Gbps duobinary-NRZ and 4-PAM over 100m OM-3 fiber employing a linear equalizer in the receiver....

A programmable CCD driver circuit for multiphase CCD operation

International Nuclear Information System (INIS)

Ewin, A.J.; Reed, K.V.

1989-01-01

A programmable CCD driver circuit was designed to drive CCD's in multiphased modes. The purpose of the drive electronics was to operate developmental CCD imaging arrays for NASA's Moderate Resolution Imaging Spectrometer - Tiltable (MODIS-T). Five prototype arrays were designed. Valid's Graphics Editor (GED) was used to design the driver. With this driver design, any of the five arrays can be readout. Designing the driver with GED allowed functional simulation, timing verification, and certain packaging analyses to be done on the design before fabrication. The driver verified its function with the master clock running up to 10 MHz. This suggests a maximum rate of 400 Kpixels/sec. Timing and packaging parameters were verified. the design uses 54 TTL component chips

MIMO-OFDM WDM PON with DM-VCSEL for femtocells application

DEFF Research Database (Denmark)

Binti Othman, Maisara; Deng, Lei; Pang, Xiaodan

2011-01-01

We report on experimental demonstration of 2x2 MIMO-OFDM 5.6-GHz radio over fiber signaling over 20 km WDM-PON with directly modulated (DM) VCSELs for femtocells application. MIMO-OFDM algorithms effectively compensate for impairments in the wireless link. Error-free signal demodulation of 64...

Self-aligned BCB planarization method for high-frequency signal injection in a VCSEL with an integrated modulator

Science.gov (United States)

Marigo-Lombart, Ludovic; Doucet, Jean-Baptiste; Lecestre, Aurélie; Reig, Benjamin; Rousset, Bernard; Thienpont, Hugo; Panajotov, Krassimir; Almuneau, Guilhem

2016-04-01

The huge increase of datacom capacities requires lasers sources with more and more bandwidth performances. Vertical-Cavity Surface-Emitting Lasers (VCSEL) in direct modulation is a good candidate, already widely used for short communication links such as in datacenters. Recently several different approaches have been proposed to further extend the direct modulation bandwidth of these devices, by improving the VCSEL structure, or by combining the VCSEL with another high speed element such as lateral slow light modulator or transistor/laser based structure (TVCSEL). We propose to increase the modulation bandwidth by vertically integrating a continuous-wave VCSEL with a high-speed electro-modulator. This vertical structure implies multiple electrodes with sufficiently good electrical separation between the different input electrical signals. This high frequency modulation requires both good electrical insulation between metal electrodes and an optimized design of the coplanar lines. BenzoCyclobutene (BCB) thanks to its low dielectric constant, low losses, low moisture absorption and good thermal stability, is often used as insulating layer. Also, BCB planarization offers the advantages of simpler and more reliable technological process flow in such integrated VCSEL/modulator structures with important reliefs. As described by Burdeaux et al. a degree of planarization (DOP) of about 95% can be achieved by simple spin coating whatever the device thickness. In most of the cases, the BCB planarization process requires an additional photolithography step in order to open an access to the mesa surface, thus involving a tight mask alignment and resulting in a degraded planarization. In this paper, we propose a self-aligned process with improved BCB planarization by combining a hot isostatic pressing derived from nanoimprint techniques with a dry plasma etching step.

Comparison of 850-nm and 1550-nm VCSELs for low-cost short-reach IM/DD and OFDM SMF/MMF links

DEFF Research Database (Denmark)

Karinou, Fotini; Deng, Lei; Rodes Lopez, Roberto

2013-01-01

In this paper, we experimentally compare the suitability of two VCSEL designs of different wavelength and technology as inexpensive, off-the-shelf transmitter components to enable low-cost and energy-efficient optical interconnects employing conventional (NRZ IM/DD) and advanced (OFDM) modulation....... In particular, we assess the performance of a multimode (MM) 850-nm and a single-mode (SM) 1550-nm VCSEL over 100 m/1 km of 50.7-μm diameter OM-4 MMF links and 100 m/5 km SMF links. OFDM-QPSK is investigated in order to substitute IM/DD in order to increase the capacity in the aforementioned VCSEL-based, MMF...

Simultaneous 10 Gbps data and polarization-based pulse-per-second clock transmission using a single VCSEL for high-speed optical fibre access networks

Science.gov (United States)

Isoe, G. M.; Wassin, S.; Gamatham, R. R. G.; Leitch, A. W. R.; Gibbon, T. B.

2017-01-01

Access networks based on vertical cavity surface emitting laser (VCSEL) transmitters offer alternative solution in delivering different high bandwidth, cost effective services to the customer premises. Clock and reference frequency distribution is critical for applications such as Coordinated Universal Time (UTC), GPS, banking and big data science projects. Simultaneous distribution of both data and timing signals over shared infrastructure is thus desirable. In this paper, we propose and experimentally demonstrate a novel, cost-effective technique for multi-signal modulation on a single VCSEL transmitter. Two signal types, an intensity modulated 10 Gbps data signal and a polarization-based pulse per second (PPS) clock signal are directly modulated onto a single VCSEL carrier at 1310 nm. Spectral efficiency is maximized by exploiting inherent orthogonal polarization switching of the VCSEL with changing bias in transmission of the PPS signal. A 10 Gbps VCSEL transmission with PPS over 11 km of G.652 fibre introduced a transmission penalty of 0.52 dB. The contribution of PPS to this penalty was found to be 0.08 dB.

Radiation-hard/high-speed parallel optical links

International Nuclear Information System (INIS)

Gan, K.K.; Buchholz, P.; Kagan, H.P.; Kass, R.D.; Moore, J.; Smith, D.S.; Wiese, A.; Ziolkowski, M.

2014-01-01

We have designed an ASIC for use in a parallel optical engine for a new layer of the ATLAS pixel detector in the initial phase of the LHC luminosity upgrade. The ASIC is a 12-channel VCSEL (Vertical Cavity Surface Emitting Laser) array driver capable of operating up to 5 Gb/s per channel. The ASIC is designed using a 130 nm CMOS process to enhance the radiation-hardness. A scheme for redundancy has also been implemented to allow bypassing of a broken VCSEL. The ASIC also contains a power-on reset circuit that sets the ASIC to a default configuration with no signal steering. In addition, the bias and modulation currents of the individual channels are programmable. The performance of the first prototype ASIC up to 5 Gb/s is satisfactory. Furthermore, we are able to program the bias and modulation currents and to bypass a broken VCSEL channel. We are currently upgrading our design to allow operation at 10 Gb/s per channel yielding an aggregated bandwidth of 120 Gb/s. Some preliminary results of the design will be presented

24-Dimensional Modulation Formats for 100 Gbit/s IM-DD Transmission Systems Using 850 nm Single-Mode VCSEL

DEFF Research Database (Denmark)

Lu, Xiaofeng; Lyubopytov, Vladimir; Tafur Monroy, Idelfonso

2017-01-01

Twenty-four dimensional modulation format with 2 bit/symbol spectrum efficiency is proposed and investigated in an up to 100 Gbit/s VCSEL-based IM-DD transmission system with respect to the channel bandwidth and the power budget.......Twenty-four dimensional modulation format with 2 bit/symbol spectrum efficiency is proposed and investigated in an up to 100 Gbit/s VCSEL-based IM-DD transmission system with respect to the channel bandwidth and the power budget....

VCSEL Scaling, Laser Integration on Silicon, and Bit Energy

Science.gov (United States)

2017-03-01

especially the laser. Highly compact directly modulated lasers ( DMLs ) have been researched to meet this goal. The most favored technology will likely be...question of which achieves lower bit energy, a DML or a continuous-wave (CW) laser coupled to an integrated modulator. Transceiver suppliers are also...development that can utilize high efficiency DMLs that reach very high modulation speed. Oxide-VCSELs [1] do not yet take full advantage of the

Optimization of self-mixing modulation in VCSELs for sensing applications

DEFF Research Database (Denmark)

Larsson, David; Yvind, Kresten; Hvam, Jørn Märcher

2009-01-01

Ga1-xAs). The calculations are based on matrix multiplication for calculating effective reflectivity and transmission with external feedback, combined with a logarithmic gain model and standard laser rate equations. To improve the sensitivity towards self-mixing interference in VCSELs by simple...... epitaxial means and this should enable us to e.g. measure smaller bending deflections of cantilever sensors...

Diagnostic and characterization of the VCSEL diodes based on GaSb

Czech Academy of Sciences Publication Activity Database

Matulková, Irena; Cihelka, Jaroslav; Vyskočil, Jan; Zelinger, Zdeněk; Hulicius, Eduard; Šimeček, Tomislav; Civiš, Svatopluk

2010-01-01

Roč. 99, 1-2 (2010), s. 333-338 ISSN 0946-2171 R&D Projects: GA AV ČR IAA400400705 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z10100521 Keywords : VCSEL diode s * FTIR * GaSb Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.239, year: 2010

Heavy-ion driver design and scaling

International Nuclear Information System (INIS)

Bieri, R.; Monsler, M.; Meier, W.; Stewart, L.

1992-01-01

Parametric models for scaling heavy-ion driver designs are described. Scaling of target performance and driver cost is done for driver parameters including driver energy, number of beams, type of superconductor used in focusing magnets, maximum magnetic field allowed at the superconducting windings, linear quadrupole array packing fraction mass, and ion charge state. The cumulative accelerator voltage and beam currents are determined from the Maschke limits on beam current for each choice of driver energy and post-acceleration pulse duration. The heavy-ion driver is optimized over the large available driver parameter space. Parametric studies and the choice of a base driver model are described in a companion paper

10 Gb/s Real-Time All-VCSEL Low Complexity Coherent scheme for PONs

DEFF Research Database (Denmark)

Rodes Lopez, Roberto; Cheng, Ning; Jensen, Jesper Bevensee

2012-01-01

Real time demodulation of a 10 Gb/s all-VCSEL based coherent PON link with a simplified coherent receiver scheme is demonstrated. Receiver sensitivity of −33 dBm is achieved providing high splitting ratio and link reach....

Wire number dependence of the implosion dynamics, stagnation, and radiation output of tungsten wire arrays at Z driver

Energy Technology Data Exchange (ETDEWEB)

Mazarakis, Michael G.; Stygar, William A.; Sinars, Daniel B.; Cuneo, Michael E.; Nash, Thomas J.; Chandler, Gordon A.; Keith Matzen, M.; Porter, John L.; Struve, Kenneth W.; McDaniel, Dillon H. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States); Deeney, Christopher E. [National Nuclear Security Administration, Washington, D.C. 20585 (United States); Douglas, Melissa R. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Chittenden, Jerry [Imperial College, London, SW and 2BW (United Kingdom)

2011-11-15

We report results of the experimental campaign, which studied the initiation, implosion dynamics, and radiation yield of tungsten wire arrays as a function of the wire number. The wire array dimensions and mass were those of interest for the Z-pinch driven Inertial Confinement Fusion (ICF) program. An optimization study of the x-ray emitted peak power, rise time, and full width at half maximum was effectuated by varying the wire number while keeping the total array mass constant and equal to {approx}5.8 mg. The driver utilized was the {approx}20-MA Z accelerator before refurbishment in its usual short pulse mode of 100 ns. We studied single arrays of 20-mm diameter and 1-cm height. The smaller wire number studied was 30 and the largest 600. It appears that 600 is the highest achievable wire number with present day's technology. Radial and axial diagnostics were utilized including crystal monochromatic x-ray backlighter. An optimum wire number of {approx}375 was observed which was very close to the routinely utilized 300 for the ICF program in Sandia.

Wire number dependence of the implosion dynamics, stagnation, and radiation output of tungsten wire arrays at Z driver

International Nuclear Information System (INIS)

Mazarakis, Michael G.; Stygar, William A.; Sinars, Daniel B.; Cuneo, Michael E.; Nash, Thomas J.; Chandler, Gordon A.; Keith Matzen, M.; Porter, John L.; Struve, Kenneth W.; McDaniel, Dillon H.; Deeney, Christopher E.; Douglas, Melissa R.; Chittenden, Jerry

2011-01-01

We report results of the experimental campaign, which studied the initiation, implosion dynamics, and radiation yield of tungsten wire arrays as a function of the wire number. The wire array dimensions and mass were those of interest for the Z-pinch driven Inertial Confinement Fusion (ICF) program. An optimization study of the x-ray emitted peak power, rise time, and full width at half maximum was effectuated by varying the wire number while keeping the total array mass constant and equal to ∼5.8 mg. The driver utilized was the ∼20-MA Z accelerator before refurbishment in its usual short pulse mode of 100 ns. We studied single arrays of 20-mm diameter and 1-cm height. The smaller wire number studied was 30 and the largest 600. It appears that 600 is the highest achievable wire number with present day's technology. Radial and axial diagnostics were utilized including crystal monochromatic x-ray backlighter. An optimum wire number of ∼375 was observed which was very close to the routinely utilized 300 for the ICF program in Sandia.

Radiation hardness and lifetime studies of LEDs and VCSELs for the optical readout of the ATLAS SCT

CERN Document Server

Beringer, J; Mommsen, R K; Nickerson, R B; Weidberg, A R; Monnier, E; Hou, H Q; Lear, K L

1999-01-01

We study the radiation hardness and the lifetime of Light Emitting Diodes (LEDs) and Vertical Cavity Surface Emitting Laser diodes (VCSELs) in the context of the development of the optical readout for the ATLAS SemiConductor Tracker (SCT) at LHC. About 170 LEDs from two different manufacturers and about 130 VCSELs were irradiated with neutron and proton fluences equivalent to (and in some cases more than twice as high as) the combined neutral and charged particle fluence of about 5x10 sup 1 sup 4 n (1 MeV eq. in GaAs)/cm sup 2 expected in the ATLAS inner detector. We report on the radiation damage and the conditions required for its partial annealing under forward bias, we calculate radiation damage constants, and we present post-irradiation failure rates for LEDs and VCSELs. The lifetime after irradiation was investigated by operating the diodes at an elevated temperature of 50 degree sign C for several months, resulting in operating times corresponding to up to 70 years of operation in the ATLAS SCT. From o...

VCSEL-based gigabit IR-UWB link for converged communication and sensing applications in optical metro-access networks

DEFF Research Database (Denmark)

Pham, Tien Thang; Gibbon, Timothy Braidwood; Tafur Monroy, Idelfonso

2012-01-01

We report on experimental demonstration of an impulse radio ultrawideband (IR-UWB) based converged communication and sensing system. A 1550-nm VCSEL-generated IR-UWB signal is used for 2-Gbps wireless data distribution over 800-m and 50-km single mode fiber links which present short-range in-buil...... application, paving the way forward for the development and deployment of converged UWB VCSEL-based technologies in access and in-building networks of the future.......We report on experimental demonstration of an impulse radio ultrawideband (IR-UWB) based converged communication and sensing system. A 1550-nm VCSEL-generated IR-UWB signal is used for 2-Gbps wireless data distribution over 800-m and 50-km single mode fiber links which present short-range in......-building and long-reach access network applications. The IR-UWB signal is also used to simultaneously measure the rotational speed of a blade spinning between 18 and 30 Hz. To the best of our knowledge, this is the very first demonstration of a simultaneous gigabit UWB telecommunication and wireless UWB sensing...

Real-time multi-target ranging based on chaotic polarization laser radars in the drive-response VCSELs.

Science.gov (United States)

Zhong, Dongzhou; Xu, Geliang; Luo, Wei; Xiao, Zhenzhen

2017-09-04

According to the principle of complete chaos synchronization and the theory of Hilbert phase transformation, we propose a novel real-time multi-target ranging scheme by using chaotic polarization laser radar in the drive-response vertical-cavity surface-emitting lasers (VCSELs). In the scheme, to ensure each polarization component (PC) of the master VCSEL (MVCSEL) to be synchronized steadily with that of the slave VCSEL, the output x-PC and y-PC from the MVCSEL in the drive system and those in the response system are modulated by the linear electro-optic effect simultaneously. Under this condition, by simulating the influences of some key parameters of the system on the synchronization quality and the relative errors of the two-target ranging, related operating parameters can be optimized. The x-PC and the y-PC, as two chaotic radar sources, are used to implement the real-time ranging for two targets. It is found that the measured distances of the two targets at arbitrary position exhibit strong real-time stability and only slight jitter. Their resolutions are up to millimeters, and their relative errors are very small and less than 2.7%.

Heavy-ion driver parametric studies and choice of a base 5 mega-joule driver design

International Nuclear Information System (INIS)

Bieri, R.; Meier, W.

1992-01-01

Parametric studies to optimize heavy-ion driver designs are described and an optimized 5 MJ driver design is described. Parametric studies are done on driver parameters including driver energy, number of beams, type of superconductor used in focusing magnets, maximum magnetic field allowed at the superconducting windings, axial quadrupole field packing fraction, ion mass, and ion charge state. All modeled drivers use the maximum beam currents allowed by the Maschke limits; driver scaling is described in a companion paper. The optimized driver described is conservative and cost effective. The base driver direct costs are only $120/Joule, and the base driver uses no recirculation, beam combination, or beam separation. The low driver cost achieved is due, in part, to the use of compact Nb 3 Sn quadrupole arrays, but results primarily from optimization over the large, multi-dimensional, parameter space available for heavy-ion drivers

Quad 14Gbps L-Band VCSEL-based System for WDM Migration of 4-lanes 56 Gbps Optical Data Links

DEFF Research Database (Denmark)

Estaran Tolosa, Jose Manuel; Rodes Lopez, Roberto; Pham, Tien Thang

2012-01-01

We report on migrating multiple lane link into a single WDM L-band VCSEL-based system. Experimental validation successfully achieves 10 km of SMF reach with 4x14Gbps and less than 0.5dB inter-channel crosstalk penalty.......We report on migrating multiple lane link into a single WDM L-band VCSEL-based system. Experimental validation successfully achieves 10 km of SMF reach with 4x14Gbps and less than 0.5dB inter-channel crosstalk penalty....

Reach Extension and Capacity Enhancement of VCSEL-Based Transmission Over Single-Lane MMF Links

DEFF Research Database (Denmark)

Tatarczak, Anna; Motaghiannezam, S. M. Reza; Kocot, Chris

2017-01-01

This paper reviews and examines several techniques for expanding the carrying capacity of multimode fiber (MMF) using vertical cavity surface emitting lasers (VCSELs). The first approach utilizes short wavelength division multiplexing in combination with MMF optimized for operation between 850 an...

IM/DD vs. 4-PAM Using a 1550-nm VCSEL over Short-Range SMF/MMF Links for Optical Interconnects

DEFF Research Database (Denmark)

Karinou, Fotini; Rodes Lopez, Roberto; Prince, Kamau

2013-01-01

We experimentally compare the performance of 10.9-Gb/s IM/DD and 5-GBd 4-PAM modulation formats over 5-km SMF and 1-km MMF links, employing a commercially-available 1550-nm VCSEL as an enabling technology for use in optical interconnects.......We experimentally compare the performance of 10.9-Gb/s IM/DD and 5-GBd 4-PAM modulation formats over 5-km SMF and 1-km MMF links, employing a commercially-available 1550-nm VCSEL as an enabling technology for use in optical interconnects....

Capacity upgrade in short-reach optical fibre networks: simultaneous 4-PAM 20 Gbps data and polarization-modulated PPS clock signal using a single VCSEL carrier

Science.gov (United States)

Isoe, G. M.; Wassin, S.; Gamatham, R. R. G.; Leitch, A. W. R.; Gibbon, T. B.

2017-11-01

In this work, a four-level pulse amplitude modulation (4-PAM) format with a polarization-modulated pulse per second (PPS) clock signal using a single vertical cavity surface emitting laser (VCSEL) carrier is for the first time experimentally demonstrated. We propose uncomplex alternative technique for increasing capacity and flexibility in short-reach optical communication links through multi-signal modulation onto a single VCSEL carrier. A 20 Gbps 4-PAM data signal is directly modulated onto a single mode 10 GHz bandwidth VCSEL carrier at 1310 nm, therefore, doubling the network bit rate. Carrier spectral efficiency is further maximized by exploiting the inherent orthogonal polarization switching of the VCSEL carrier with changing bias in transmission of a PPS clock signal. We, therefore, simultaneously transmit a 20 Gbps 4-PAM data signal and a polarization-based PPS clock signal using a single VCSEL carrier. It is the first time a signal VCSEL carrier is reported to simultaneously transmit a directly modulated 20 Gbps 4-PAM data signal and a polarization-based PPS clock signal. We further demonstrate on the design of a software-defined digital signal processing (DSP)-assisted receiver as an alternative to costly receiver hardware. Experimental results show that a 3.21 km fibre transmission with simultaneous 20 Gbps 4-PAM data signal and polarization-based PPS clock signal introduced a penalty of 3.76 dB. The contribution of polarization-based PPS clock signal to this penalty was found out to be 0.41 dB. Simultaneous distribution of data and timing clock signals over shared network infrastructure significantly increases the aggregated data rate at different optical network units (ONUs), without costly investment.

In-building Unlicensed WiFi Band OFDM Signal Distribution over MMF&BIF Using VCSEL

DEFF Research Database (Denmark)

Deng, Lei; Jensen, Jesper Bevensee; Yu, Xianbin

2011-01-01

For in-building applications, an OFDM-VCSEL RoF system operating in unlicensed WiFi band is experimentally tested using MMF and bend insensitive fiber (BIF). A spectral efficiency of 4.32 bit/s/Hz with 0.9 Gbps data rate is achieved....

Incorporating antenna beamswitching technique into drivers for IEEE802.11 WLAN devices

CSIR Research Space (South Africa)

Mofolo, M

2015-11-23

Full Text Available the beamswitching technique for switched parasitic array (SPA) and electronically steerable parasitic array radiator (ESPAR) antennas in the drivers for IEEE802.11 WLAN devices. The modifications of the open source drivers (ath5k and ath9k) to enable real...

InGaAs focal plane arrays for low-light-level SWIR imaging

Science.gov (United States)

MacDougal, Michael; Hood, Andrew; Geske, Jon; Wang, Jim; Patel, Falgun; Follman, David; Manzo, Juan; Getty, Jonathan

2011-06-01

Aerius Photonics will present their latest developments in large InGaAs focal plane arrays, which are used for low light level imaging in the short wavelength infrared (SWIR) regime. Aerius will present imaging in both 1280x1024 and 640x512 formats. Aerius will present characterization of the FPA including dark current measurements. Aerius will also show the results of development of SWIR FPAs for high temperaures, including imagery and dark current data. Finally, Aerius will show results of using the SWIR camera with Aerius' SWIR illuminators using VCSEL technology.

Systematic characterization of a 1550 nm microelectromechanical (MEMS)-tunable vertical-cavity surface-emitting laser (VCSEL) with 7.92 THz tuning range for terahertz photomixing systems

Science.gov (United States)

Haidar, M. T.; Preu, S.; Cesar, J.; Paul, S.; Hajo, A. S.; Neumeyr, C.; Maune, H.; Küppers, F.

2018-01-01

Continuous-wave (CW) terahertz (THz) photomixing requires compact, widely tunable, mode-hop-free driving lasers. We present a single-mode microelectromechanical system (MEMS)-tunable vertical-cavity surface-emitting laser (VCSEL) featuring an electrothermal tuning range of 64 nm (7.92 THz) that exceeds the tuning range of commercially available distributed-feedback laser (DFB) diodes (˜4.8 nm) by a factor of about 13. We first review the underlying theory and perform a systematic characterization of the MEMS-VCSEL, with particular focus on the parameters relevant for THz photomixing. These parameters include mode-hop-free CW tuning with a side-mode-suppression-ratio >50 dB, a linewidth as narrow as 46.1 MHz, and wavelength and polarization stability. We conclude with a demonstration of a CW THz photomixing setup by subjecting the MEMS-VCSEL to optical beating with a DFB diode driving commercial photomixers. The achievable THz bandwidth is limited only by the employed photomixers. Once improved photomixers become available, electrothermally actuated MEMS-VCSELs should allow for a tuning range covering almost the whole THz domain with a single system.

Comparative study on stained InGaAs quantum wells for high-speed optical-interconnect VCSELs

Science.gov (United States)

Li, Hui; Jia, Xiaowei

2018-05-01

The gain-carrier characteristics of InGaAs quantum well for 980 nm high-speed, energy-efficient vertical-cavity surface-emitting lasers are investigated. We specially studied the potentially InGaAs quantum well designs can be used for the active region of energy-efficient, temperature-stable 980-nm VCSEL, which introduced a quantum well gain peak wavelength-to-cavity resonance wavelength offset to improve the dynamic performance at high operation temperature. Several candidate quantum wells are being compared in theory and measurement. We found that ∼5 nm InGaAs QW with ∼6 nm barrier thickness is suitable for the active region of high-speed optical interconnect 980 nm VCSELs, and no significant improvement in the 20% range of In content of InGaAs QWs. The results are useful for next generation green photonic device design.

SC-FDE for MMF short reach optical interconnects using directly modulated 850 nm VCSELs

DEFF Research Database (Denmark)

Teichmann, Victor S. C.; Barreto, Andre N.; Pham, Tien Thang

2012-01-01

We propose the use of single-carrier frequency-domain equalization (SC-FDE) for the compensation of modal dispersion in short distance optical links using multimode fibers and 850 nm VCSELs. By post-processing of experimental data, we demonstrate, at 7.9% overhead, the error-free transmission (ov...

VCSEL-based gigabit impulse radio UWB for converged wireless sensor and communication in-building networks

DEFF Research Database (Denmark)

Gibbon, Timothy Braidwood; Pham, Tien Thang; Neumeyr, C.

2010-01-01

A 1550nm VCSEL-generated UWB signal is used for simultaneous 2Gb/s wireless data transfer and to measuring the rotational speed of a blade spinning between 18-29Hz, with up to 50km distribution over single mode fibre....

Ultrahigh speed endoscopic optical coherence tomography using micromotor imaging catheter and VCSEL technology.

Science.gov (United States)

Tsai, Tsung-Han; Potsaid, Benjamin; Tao, Yuankai K; Jayaraman, Vijaysekhar; Jiang, James; Heim, Peter J S; Kraus, Martin F; Zhou, Chao; Hornegger, Joachim; Mashimo, Hiroshi; Cable, Alex E; Fujimoto, James G

2013-07-01

We developed a micromotor based miniature catheter with an outer diameter of 3.2 mm for ultrahigh speed endoscopic swept source optical coherence tomography (OCT) using a vertical cavity surface-emitting laser (VCSEL) at a 1 MHz axial scan rate. The micromotor can rotate a micro-prism at several hundred frames per second with less than 5 V drive voltage to provide fast and stable scanning, which is not sensitive to the bending of the catheter. The side-viewing probe can be pulled back to acquire a three-dimensional (3D) data set covering a large area on the specimen. The VCSEL provides a high axial scan rate to support dense sampling under high frame rate operation. Using a high speed data acquisition system, in vivo 3D-OCT imaging in the rabbit GI tract and ex vivo imaging of a human colon specimen with 8 μm axial resolution, 8 μm lateral resolution and 1.2 mm depth range in tissue at a frame rate of 400 fps was demonstrated.

Using a Single VCSEL Source Employing OFDM Downstream Signal and Remodulated OOK Upstream Signal for Bi-directional Visible Light Communications.

Science.gov (United States)

Yeh, Chien-Hung; Wei, Liang-Yu; Chow, Chi-Wai

2017-11-20

In this work, we propose and demonstrate for the first time up to our knowledge, using a 682 nm visible vertical-cavity surface-emitting laser (VCSEL) applied in a bi-directional wavelength remodulated VLC system with a free space transmission distance of 3 m. To achieve a high VLC downstream traffic, spectral efficient orthogonal-frequency-division-multiplexing quadrature-amplitude-modulation (OFDM-QAM) with bit and power loading algorithms are applied on the VCSEL in the central office (CO). The OFDM downstream wavelength is remodulated by an acousto-optic modulator (AOM) with OOK modulation to produce the upstream traffic in the client side. Hence, only a single VCSEL laser is needed for the proposed bi-directional VLC system, achieving 10.6 Gbit/s OFDM downstream and 2 Mbit/s remodulated OOK upstream simultaneously. For the proposed system, as a single laser source with wavelength remodulation is used, the laser wavelength and temperature managements at the client side are not needed; and the whole system could be cost effective and energy efficient.

Sub-cycle QAM modulation for VCSEL-based optical fiber links

DEFF Research Database (Denmark)

Pham, Tien-Thang; Rodes Lopez, Roberto; Jensen, Jesper Bevensee

2013-01-01

QAM modulation utilizing subcarrier frequency lower than the symbol rate is both theoretically and experimentally investigated. High spectral efficiency and concentration of power in low frequencies make sub-cycle QAM signals attractive for optical fiber links with direct modulated light sources....... Real-time generated 10-Gbps 4-level QAM signal in a 7.5-GHz bandwidth utilizing subcarrier frequency at a half symbol rate was successfully transmitted over 20-km SMF using an un-cooled 1.5-μm VCSEL. Only 2.5-dB fiber transmission power penalty was observed with no equalization applied....

Eight dimensional optimized modulation for IM-DD 56 Gbit/s optical interconnections using 850 nm vcsels

DEFF Research Database (Denmark)

Lu, Xiaofeng; Tatarczak, Anna; Tafur Monroy, Idelfonso

2016-01-01

A novel 8-dimensional optimized modulation format is designed and compared with PAM-n in a 28-GBd 850 nm VCSEL based IM-DD system, enabling the transmission on 100GBASE-SR4 FEC threshold over various 100 m MMF links....

A top-down design methodology and its implementation for VCSEL-based optical links design

Science.gov (United States)

Li, Jiguang; Cao, Mingcui; Cai, Zilong

2005-01-01

In order to find the optimal design for a given specification of an optical communication link, an integrated simulation of electronic, optoelectronic, and optical components of a complete system is required. It is very important to be able to simulate at both system level and detailed model level. This kind of model is feasible due to the high potential of Verilog-AMS language. In this paper, we propose an effective top-down design methodology and employ it in the development of a complete VCSEL-based optical links simulation. The principle of top-down methodology is that the development would proceed from the system to device level. To design a hierarchical model for VCSEL based optical links, the design framework is organized in three levels of hierarchy. The models are developed, and implemented in Verilog-AMS. Therefore, the model parameters are fitted to measured data. A sample transient simulation demonstrates the functioning of our implementation. Suggestions for future directions in top-down methodology used for optoelectronic systems technology are also presented.

A UNIX device driver for a Translink II Transputer board

International Nuclear Information System (INIS)

Wiley, J.C.

1991-01-01

A UNIX device driver for a TransLink II Transputer board is described. A complete listing of the code is presented. The device driver allows a transputer array to be used with the A/UX operating system

Coupled Photonic Crystal Cavity Array Laser

DEFF Research Database (Denmark)

Schubert, Martin

in the quadratic lattice. Processing techniques are developed and optimized in order fabricate photonic crystals membranes in gallium arsenide with quantum dots as gain medium and in indium gallium arsenide phosphide with quantum wells as gain medium. Several key issues in process to ensure good quality....... The results are in good agreement with standard coupled mode theory. Also a novel type of photonic crystal structure is proposed called lambda shifted cavity which is a twodimensional photonic crystal laser analog of a VCSEL laser. Detailed measurements of the coupled modes in the photonic crystals...... with quantum dots are carried out. In agreement with a simple gain model the structures do not show stimulated emission. The spectral splitting due to the coupling between single cavities as well as arrays of cavities is studied theoretically and experimentally. Lasing is observed for photonic crystal cavity...

Commercial/industrial photovoltaic module and array requirement study. Low-cost solar array project engineering area

Science.gov (United States)

1981-01-01

Design requirements for photovoltaic modules and arrays used in commercial and industrial applications were identified. Building codes and referenced standards were reviewed for their applicability to commercial and industrial photovoltaic array installation. Four general installation types were identified - integral (replaces roofing), direct (mounted on top of roofing), stand-off (mounted away from roofing), and rack (for flat or low slope roofs, or ground mounted). Each of the generic mounting types can be used in vertical wall mounting systems. This implies eight mounting types exist in the commercial/industrial sector. Installation costs were developed for these mounting types as a function of panel/module size. Cost drivers were identified. Studies were performed to identify optimum module shapes and sizes and operating voltage cost drivers. The general conclusion is that there are no perceived major obstacles to the use of photovoltaic modules in commercial/industrial arrays.

The miniature optical transmitter and transceiver for the High-Luminosity LHC (HL-LHC) experiments

International Nuclear Information System (INIS)

Liu, C; Zhao, X; Deng, B; Gong, D; Guo, D; Li, X; Liang, F; Liu, G; Liu, T; Xiang, A C; Ye, J; Chen, J; Huang, D; Hou, S; Teng, P-K

2013-01-01

We present the design and test results of the Miniature optical Transmitter (MTx) and Transceiver (MTRx) for the high luminosity LHC (HL-LHC) experiments. MTx and MTRx are Transmitter Optical Subassembly (TOSA) and Receiver Optical Subassembly (ROSA) based. There are two major developments: the Vertical Cavity Surface Emitting Laser (VCSEL) driver ASIC LOCld and the mechanical latch that provides the connection to fibers. In this paper, we concentrate on the justification of this work, the design of the latch and the test results of these two modules with a Commercial Off-The-Shelf (COTS) VCSEL driver

A CMOS 0.13 mu m, 5-Gb/s laser driver for high energy physics applications

CERN Document Server

Mazza, G; Moreira, P; Rivetti, A; Soos, C; Troska, J; Wyllie, K

2012-01-01

The GigaBit Laser Driver (GBLD) is a radiation tolerant ASIC designed to drive both edge emitting lasers and VCSELs at data rates up to 5 Gb/s. It is part of the GigaBit Transceiver (GBT) and Versatile Link projects, which are designing a bi-directional optical data transmission system capable of operating in the radiation environment of a typical HEP experiment. The GBLD can provide laser diode modulation currents up to 24 mA and laser bias currents up to 43 mA. Pre- and de-emphasis functions are implemented to compensate for high external capacitive loads and asymmetric laser response. The chip, designed in a 0.13 $\\mu$m CMOS technology, is powered by a single 2.5 V power supply and can be programmed via an $I2C$ interface.

Growth of GaAs-based VCSEL/RCE Structures for Optoelectronic Applications via Molecular Beam Epitaxy

OpenAIRE

A. S. Somintac; E. Estacio,; M. F. Bailon; A. A. Salvador

2003-01-01

High intensity and sharp emission peaks, at light-hole (842 nm) and heavy-hole (857 nm) excitonic transitionsfor a 90 Å GaAs quantum well (QW) were observed for vertical-cavity surface-emitting laser (VCSEL)structure. Excellent wavelength selectivity and sensitivity were demonstrated by resonant cavity enhanced(RCE) photodetector at 859 nm, corresponding to the energy level of a 95 Å GaAs quantum well.

Highly strained InGaAs oxide confined VCSELs emitting in 1.25 μm

International Nuclear Information System (INIS)

Chang, S.J.; Yu, H.C.; Su, Y.K.; Chen, I.L.; Lee, T.D.; Lu, C.M.; Chiou, C.H.; Lee, Z.H.; Yang, H.P.; Sung, C.P.

2005-01-01

Highly strained GaAs-based all-epitaxial oxide confined vertical cavity surface emitting lasers (VCSELs) emitting in 1.25 μm were fabricated. Compared with the designed cavity resonance, it was found that lasing wavelength blue shifted by 29 nm when the driving current was small. The observation of such oxide mode is attributed to the effective optical thickness shrinkage of the oxide layer, and large detuning between the gain peak and cavity resonance

Time skewing and amplitude nonlinearity mitigation by feedback equalization for 56 Gbps VCSEL-based PAM-4 links

Science.gov (United States)

You, Yue; Zhang, Wenjia; Sun, Lin; Du, Jiangbing; Liang, Chenyu; Yang, Fan; He, Zuyuan

2018-03-01

The vertical cavity surface emitting laser (VCSEL)-based multimode optical transceivers enabled by pulse amplitude modulation (PAM)-4 will be commercialized in near future to meet the 400-Gbps standard short reach optical interconnects. It is still challenging to achieve over 56/112-Gbps with the multilevel signaling as the multimode property of the device and link would introduce the nonlinear temporal response for the different levels. In this work, we scrutinize the distortions that relates to the multilevel feature of PAM-4 modulation, and propose an effective feedback equalization scheme for 56-Gbps VCSEL-based PAM-4 optical interconnects system to mitigate the distortions caused by eye timing-skew and nonlinear power-dependent noise. Level redistribution at Tx side is theoretically modeled and constructed to achieve equivalent symbol error ratios (SERs) of four levels and improved BER performance. The cause of the eye skewing and the mitigation approach are also simulated at 100-Gbps and experimentally investigated at 56-Gbps. The results indicate more than 2-dB power penalty improvement has been achieved by using such a distortion aware equalizer.

Laser self-mixing interferometry in VCSELs - an ultra-compact and massproduceable deflection detection system for nanomechanical polymer cantilever sensors

DEFF Research Database (Denmark)

Larsson, David; Yvind, Kresten; Hvam, Jørn Märcher

2008-01-01

We have realised an ultra-compact deflection detection system based on laser self-mixing interferometry in a Vertical-Cavity Surface-Emitting Laser (VCSEL). The system can be used together with polymer nanomechanical cantilevers to form chemical sensors capable of detecting less than 1nm deflection....

Rectangular waveform linear transformer driver module design

International Nuclear Information System (INIS)

Zhao Yue; Xie Weiping; Zhou Liangji; Chen Lin

2014-01-01

Linear Transformer Driver is a novel pulsed power technology, its main merits include a parallel LC discharge array and Inductive Voltage Adder. The parallel LC discharge array lowers the whole circuit equivalent inductance and the Inductive Voltage Adder unites the modules in series in order to create a high electric field grads, meanwhile, restricts the high voltage in a small space. The lower inductance in favor of LTD output a fast waveform and IVA confine high voltage in secondary cavity. In recently, some LTD-based pulsed power system has been development yet. The usual LTD architecture provides damped sine shaped output pulses that may not be suitable in flash radiography, high power microwave production, z-pinch drivers, and certain other applications. A more suitable driver output pulse would have a flat or inclined top (slightly rising or falling). In this paper, we present the design of an LTD cavity that generates this type of the output pulse by including within its circular array some number of the harmonic bricks in addition to the standard bricks according to Fourier progression theory. The parallel LC discharge array circuit formula is introduced by Kirchhoff Law, and the sum of harmonic is proofed as an analytic result, meanwhile, rationality of design is proved by simulation. Varying gas spark discharge dynamic resistance with harmonic order and switches jitter are analyzed. The results are as following: The more harmonic order is an approach to the ideal rectangular waveform, but lead to more system complexity. The capacity decreases as harmonic order increase, and gas spark discharge dynamic resistance rises with the capacity. The rising time protracts and flat is decay or even vanishes and the shot to shot reproducibility is degenerate as the switches jitter is high. (authors)

Ultraino: An Open Phased-Array System for Narrowband Airborne Ultrasound Transmission.

Science.gov (United States)

Marzo, Asier; Corkett, Tom; Drinkwater, Bruce W

2018-01-01

Modern ultrasonic phased-array controllers are electronic systems capable of delaying the transmitted or received signals of multiple transducers. Configurable transmit-receive array systems, capable of electronic steering and shaping of the beam in near real-time, are available commercially, for example, for medical imaging. However, emerging applications, such as ultrasonic haptics, parametric audio, or ultrasonic levitation, require only a small subset of the capabilities provided by the existing controllers. To meet this need, we present Ultraino, a modular, inexpensive, and open platform that provides hardware, software, and example applications specifically aimed at controlling the transmission of narrowband airborne ultrasound. Our system is composed of software, driver boards, and arrays that enable users to quickly and efficiently perform research in various emerging applications. The software can be used to define array geometries, simulate the acoustic field in real time, and control the connected driver boards. The driver board design is based on an Arduino Mega and can control 64 channels with a square wave of up to 17 Vpp and /5 phase resolution. Multiple boards can be chained together to increase the number of channels. The 40-kHz arrays with flat and spherical geometries are demonstrated for parametric audio generation, acoustic levitation, and haptic feedback.

Microfabricated Ion Beam Drivers for Magnetized Target Fusion

Science.gov (United States)

Persaud, Arun; Seidl, Peter; Ji, Qing; Ardanuc, Serhan; Miller, Joseph; Lal, Amit; Schenkel, Thomas

2015-11-01

Efficient, low-cost drivers are important for Magnetized Target Fusion (MTF). Ion beams offer a high degree of control to deliver the required mega joules of driver energy for MTF and they can be matched to several types of magnetized fuel targets, including compact toroids and solid targets. We describe an ion beam driver approach based on the MEQALAC concept (Multiple Electrostatic Quadrupole Array Linear Accelerator) with many beamlets in an array of micro-fabricated channels. The channels consist of a lattice of electrostatic quadrupoles (ESQ) for focusing and of radio-frequency (RF) electrodes for ion acceleration. Simulations with particle-in-cell and beam envelope codes predict >10x higher current densities compared to state-of-the-art ion accelerators. This increase results from dividing the total ion beam current up into many beamlets to control space charge forces. Focusing elements can be biased taking advantage of high breakdown electric fields in sub-mm structures formed using MEMS techniques (Micro-Electro-Mechanical Systems). We will present results on ion beam transport and acceleration in MEMS based beamlets. Acknowledgments: This work is supported by the U.S. DOE under Contract No. DE-AC02-05CH11231.

Radiation-hard/high-speed parallel optical links

Energy Technology Data Exchange (ETDEWEB)

Gan, K.K., E-mail: gan@mps.ohio-state.edu [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); Buchholz, P.; Heidbrink, S. [Fachbereich Physik, Universität Siegen, Siegen (Germany); Kagan, H.P.; Kass, R.D.; Moore, J.; Smith, D.S. [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); Vogt, M.; Ziolkowski, M. [Fachbereich Physik, Universität Siegen, Siegen (Germany)

2016-09-21

We have designed and fabricated a compact parallel optical engine for transmitting data at 5 Gb/s. The device consists of a 4-channel ASIC driving a VCSEL (Vertical Cavity Surface Emitting Laser) array in an optical package. The ASIC is designed using only core transistors in a 65 nm CMOS process to enhance the radiation-hardness. The ASIC contains an 8-bit DAC to control the bias and modulation currents of the individual channels in the VCSEL array. The performance of the optical engine up at 5 Gb/s is satisfactory.

Quad 14 Gbps L-band VCSEL-based system for WDM migration of 4-lanes 56 Gbps optical data links

DEFF Research Database (Denmark)

Estaran Tolosa, Jose Manuel; Rodes Lopez, Roberto; Pham, Tien Thang

2012-01-01

We report on migrating multiple-lane link into an L-band VCSEL-based WDM system. Experimental validation achieves successful transmission over 10 km of SMF at 4x14Gbps. Inter-channel crosstalk penalty is observed to be less than 0.5 dB and a transmission penalty around 1 dB. The power budget margin...

Review The Ooty Wide Field Array

Indian Academy of Sciences (India)

c Indian Academy of Sciences. DOI 10.1007/s12036-017-9430-4. Review. The Ooty Wide Field ... salient features of the upgrade, as well as its main science drivers. There are three ..... tecture for low frequency arrays, Ph.D. thesis, Jawaharalal.

A linear laser-driver array for optical transmission in the LHC experiments

CERN Document Server

Cervelli, G; Moreira, P; Vasey, F

2000-01-01

A 4-way linear laser driver has been designed and implemented in a commercial 0.25 mu m CMOS technology. The full-custom IC is intended for analogue and digital data transmission as part of the 50 000 optical fibre links of the CMS particle tracking system. Intrinsic radiation tolerance and specific design methodologies enable the device to operate over 10 years in the harsh radiation environment of the innermost LHC detectors. Although optimised for analogue operation the driver is compatible with LVDS digital signalling. A combination of linearization methods achieves good analogue performance (8-bit equivalent dynamic range with a bandwidth of 100 MHz), while maintaining wide input common-mode range (+or-350 mV) and limited power dissipation. The linearly amplified signal is added to a DC current, which can be set over a wide range (-60 mA to +60 mA). The latter capability allows tracking of changes in laser threshold due to ageing or radiation damage. The driver gain and bias current are set via a serial ...

Performance of a 60-GHz DCM-OFDM and BPSK-Impulse Ultra-Wideband System with Radio-Over-Fiber and Wireless Transmission Employing a Directly-Modulated VCSEL

DEFF Research Database (Denmark)

Beltrán, Marta; Jensen, Jesper Bevensee; Yu, Xianbin

2011-01-01

The performance of radio-over-fiber optical transmission employing vertical-cavity surface-emitting lasers (VCSELs), and further wireless transmission, of the two major ultra-wideband (UWB) implementations is reported when operating in the 60-GHz radio band. Performance is evaluated at 1.44 Gbit...... in bend-insensitive single-mode fiber with wireless transmission up to 5 m in both cases is demonstrated with no penalty. A simulation analysis has also been performed in order to investigate the operational limits. The analysis results are in excellent agreement with the experimental work and indicate...... good tolerance to chromatic dispersion due to the chirp characteristics of electro-optical conversion when a directly-modulated VCSEL is employed. The performance comparison indicates that BPSK-IR UWB exhibits better tolerance to optical transmission impairments requiring lower received optical power...

Opto-VLSI-based reconfigurable free-space optical interconnects architecture

DEFF Research Database (Denmark)

Aljada, Muhsen; Alameh, Kamal; Chung, Il-Sug

2007-01-01

is the Opto-VLSI processor which can be driven by digital phase steering and multicasting holograms that reconfigure the optical interconnects between the input and output ports. The optical interconnects architecture is experimentally demonstrated at 2.5 Gbps using high-speed 1×3 VCSEL array and 1......×3 photoreceiver array in conjunction with two 1×4096 pixel Opto-VLSI processors. The minimisation of the crosstalk between the output ports is achieved by appropriately aligning the VCSEL and PD elements with respect to the Opto-VLSI processors and driving the latter with optimal steering phase holograms....

Aging and environmental tolerance of an optical transmitter for the ATLAS Phase-I upgrade at the LHC

Energy Technology Data Exchange (ETDEWEB)

Chang, F.X. [Academia Sinica, Taipei, Taiwan (China); Chang, H.T. [Liverage Technology Inc., Chupei, Taiwan (China); Duh, T.S. [Institute of Nuclear Energy Research, Longtan, Taiwan (China); Hayamizu, T. [CYRIC, Tohoku University, Sendai (Japan); Hou, S. [Academia Sinica, Taipei, Taiwan (China); Hu, X. [Michigan University, Ann Arbor, MI (United States); Liu, C.; Liu, T. [Southern Methodist University, Dallas, TX (United States); Sakemi, Y. [CYRIC, Tohoku University, Sendai (Japan); Schwarz, T. [Michigan University, Ann Arbor, MI (United States); Teng, P.K.; Tsai, P.R. [Academia Sinica, Taipei, Taiwan (China); Wang, C.H. [National United University, Miaoli, Taiwan (China); Wang, S.Y. [Liverage Technology Inc., Chupei, Taiwan (China); Yang, Y. [National Cheng Kung University, Tainan, Taiwan (China); Ye, J. [Southern Methodist University, Dallas, TX (United States)

2016-09-21

The dual channel Miniature optical Transmitter (MTx) is developed for the ATLAS Phase-I upgrade requiring durable performance in the Large Hadron Collider environment. The data transmission has achieved 8 Gbps per channel with a custom-designed LOCld laser driver and 850 nm VCSELs packaged in transmitter optical sub-assemblies (TOSAs). The performance of the MTx opto-electronics is evaluated. Accelerated aging tests of the VCSELs were conducted in a chamber at 85 °C, 85% relative humidity, with TOSA and bare-die samples prepared in non-hermetic condition. Radiation tolerance of the VCSELs was investigated with 30 MeV and 70 MeV protons. The radiation induced effects in data transmission were investigated for light-power degradation and parameters of eye-diagrams.

Quasi-CW 110 kW AlGaAs laser diode array module for inertial fusion energy laser driver

International Nuclear Information System (INIS)

Kawashima, Toshiyuki

2001-01-01

We have successfully demonstrated a large aperture 803 nm AlGaAs diode laser module as a pump source for a 1053 nm, 10 J output Nd: glass slab laser amplifier for diode-pumped solid-state laser (DPSSL) fusion driver. Detailed performance results of the laser diode module are presented, including bar package and stack configuration, and their thermal design and analysis. A sufficiently low thermal impedance of the stack was realized by combining backplane liquid cooling configuration with modular bar package architecture. Total peak power of 110 kW and electrical to optical conversion efficiently of 46% were obtained from the module consisting of a total of 1000 laser diode bars. A peak intensity of 2.6 kW/cm 2 was accomplished across an emitting area of 418 mm x 10 mm. Currently, this laser diode array module with a large two-dimensional aperture is, to our knowledge, the only operational pump source for the high output energy DPSSL. (author)

Full 3D FDTD analysis of Electromagnetic Field in Photonic Crystal VCSEL

International Nuclear Information System (INIS)

Liu Fa; Xu Chen; Xie Yiyang; Zhao Zhenbo; Zhou Kang; Wang Baoqiang; Liu Yingming; Shen Guangdi

2011-01-01

The effect of etch damage to the mode characteristics of photonic crystal vertical cavity surface emitting lasers was simulated in this paper. The devices simulated in this paper are 850-nm GaAs-based VCSELs with photonic crystal. And the devices were simulated by using finite difference time domain (FDTD) method. Limited to the computer resource, the top DBR was simulated only, and the traverse size was smaller than the real size. In order to highlight the impact of the etch damage, several kinds of light sources and photonic crystal structures were simulated separately, and each situation is calculated in the condition of ideal photonic crystal and photonic crystal with etch damage respectively. All parameters of device and light feature are referred to the real condition.

Full 3D FDTD analysis of Electromagnetic Field in Photonic Crystal VCSEL

Energy Technology Data Exchange (ETDEWEB)

Liu Fa; Xu Chen; Xie Yiyang; Zhao Zhenbo; Zhou Kang; Wang Baoqiang; Liu Yingming; Shen Guangdi, E-mail: liufa20719@126.com [Key Laboratory of Opto-electronics Technology (Beijing University of Technology), Ministry of Education, Beijing University of Technology, 100 Ping Le Yuan, Chaoyang District, Beijing 100124 (China)

2011-02-01

The effect of etch damage to the mode characteristics of photonic crystal vertical cavity surface emitting lasers was simulated in this paper. The devices simulated in this paper are 850-nm GaAs-based VCSELs with photonic crystal. And the devices were simulated by using finite difference time domain (FDTD) method. Limited to the computer resource, the top DBR was simulated only, and the traverse size was smaller than the real size. In order to highlight the impact of the etch damage, several kinds of light sources and photonic crystal structures were simulated separately, and each situation is calculated in the condition of ideal photonic crystal and photonic crystal with etch damage respectively. All parameters of device and light feature are referred to the real condition.

56 Gb/s DMT transmission with VCSELs in 1.5 um wavelength range over up to 12 km for DWDM intra-data center connects

DEFF Research Database (Denmark)

Dochhan, Annika; Eiselt, Nicklas; Hohenleitner, Robert

2016-01-01

We demonstrate up to 12 km, 56 Gb/s DMT transmission using high-speed VCSELs in the 1.5 um wavelength range for future 400Gb/s intra-data center connects, enabled by vestigial sideband filtering of the transmit signal....

Experimental Analysis of 60-GHz VCSEL and ECL Photonic Generation and Transmission of Impulse-Radio Ultra-Wideband Signals

DEFF Research Database (Denmark)

Beltran, Marta; Jensen, Jesper Bevensee; Llorente, Roberto

2011-01-01

for comparison purposes. Real-time bit-error-rate (BER) performance of generated signals at 3.125 Gb/s is evaluated combining fiber and 2-m wireless transmission. Different optical fiber types including 1-km bend-insensitive single-mode fiber and 20-km nonzero dispersion-shifted fiber is evaluated. $\\hbox......{BER} for the ECL and $\\hbox{BER} for the VCSEL requiring higher received optical power than the ECL is demonstrated employing electrical power detection....

Systems analysis for modular versus multi-beam HIF drivers

International Nuclear Information System (INIS)

Meier, W.R.; Logan, B.G.

2004-01-01

Previous modeling for HIF drivers concentrated on designs in which 100 or more beams are grouped in an array and accelerated through a common set of induction cores. The total beam energy required by the target is achieved by the combination of final ion energy, current per beam and number of beams. Economic scaling favors a large number of small (∼1 cm dia.) beams. An alternative architecture has now been investigated, which we refer to as a modular driver. In this case, the driver is subdivided into many (>10) independent accelerators with one or many beams each. A key objective of the modular driver approach is to be able to demonstrate all aspects of the driver (source-to-target) by building a single, lower cost module compared to a full-scale, multi-beam driver. We consider and compare several design options for the modular driver including single-beam designs with solenoid instead of quadrupole magnets in order to transport the required current per module in a single beam, solenoid/quad combinations, and multi-beam, all-quad designs. The drivers are designed to meet the requirements of the hybrid target, which can accommodate a larger spot size than the distributed radiator target that was used for the Robust Point Design. We compare the multi-beam and modular driver configuration for a variety and assumptions and identify key technology advances needed for the modular design

Single-mode electrically pumped GaSb-based VCSELs emitting continuous-wave at 2.4 and 2.6 μm

International Nuclear Information System (INIS)

Bachmann, Alexander; Arafin, Shamsul; Kashani-Shirazi, Kaveh

2009-01-01

Vertical-cavity surface-emitting lasers (VCSELs) are perfect light sources for spectroscopic applications, where properties such as continuous-wave (cw) operation, single-mode emission, high lifetime and often low power consumption are crucial. For applications such as tunable diode laser absorption spectroscopy (TDLAS), there is a growing interest in laser devices emitting in the near- to mid-infrared wavelength range, where many environmentally and technologically important gases show strong absorption lines. The (AlGaIn)(AsSb) material system based on GaSb is the material of choice for covering the 2.0-3.3 μm range. In this paper, we report on electrically pumped single-mode VCSELs with emission wavelengths of 2.4 and 2.6 μm, operating cw at room temperature and beyond. By (electro-) thermal tuning, the emission wavelength can be tuned mode-hop free over a range of several nanometers. In addition, low threshold currents of several milliamperes promise mobile application. In the devices, a structured buried tunnel junction with subsequent overgrowth has been used in order to achieve efficient current confinement, reduced optical losses and increased electrical conductivity. Furthermore, strong optical confinement is introduced in the lasers due to laterally differing cavity lengths.

Design of a 5-MA 100-ns linear-transformer-driver accelerator for wire array Z-pinch experiments

Science.gov (United States)

Zhou, Lin; Li, Zhenghong; Wang, Zhen; Liang, Chuan; Li, Mingjia; Qi, Jianmin; Chu, Yanyun

2016-03-01

The linear-transformer-driver (LTD) is a recently developed pulsed-power technology that shows great promise for a number of applications. These include a Z -pinch-driven fission-fusion-hybrid reactor that is being developed by the Chinese Academy of Engineering Physics. In support of the reactor development effort, we are planning to build an LTD-based accelerator that is optimized for driving wire-array Z -pinch loads. The accelerator comprises six modules in parallel, each of which has eight series 0.8-MA LTD cavities in a voltage-adder configuration. Vacuum transmission lines are used from the interior of the adder to the central vacuum chamber where the load is placed. Thus the traditional stack-flashover problem is eliminated. The machine is 3.2 m tall and 12 m in outer diameter including supports. A prototype cavity was built and tested for more than 6000 shots intermittently at a repetition rate of 0.1 Hz. A novel trigger, in which only one input trigger pulse is needed by utilizing an internal trigger brick, was developed and successfully verified in these shots. A full circuit modeling was conducted for the accelerator. The simulation result shows that a current pulse rising to 5.2 MA in 91 ns (10%-90%) can be delivered to the wire-array load, which is 1.5 cm in height, 1.2 cm in initial radius, and 1 mg in mass. The maximum implosion velocity of the load is 32 cm /μ s when compressed to 0.1 of the initial radius. The maximum kinetic energy is 78 kJ, which is 11.7% of the electric energy stored in the capacitors. This accelerator is supposed to enable a radiation energy efficiency of 20%-30%, providing a high efficient facility for research on the fast Z pinch and technologies for repetition-rate-operated accelerators.

Multicoil resonance-based parallel array for smart wireless power delivery.

Science.gov (United States)

Mirbozorgi, S A; Sawan, M; Gosselin, B

2013-01-01

This paper presents a novel resonance-based multicoil structure as a smart power surface to wirelessly power up apparatus like mobile, animal headstage, implanted devices, etc. The proposed powering system is based on a 4-coil resonance-based inductive link, the resonance coil of which is formed by an array of several paralleled coils as a smart power transmitter. The power transmitter employs simple circuit connections and includes only one power driver circuit per multicoil resonance-based array, which enables higher power transfer efficiency and power delivery to the load. The power transmitted by the driver circuit is proportional to the load seen by the individual coil in the array. Thus, the transmitted power scales with respect to the load of the electric/electronic system to power up, and does not divide equally over every parallel coils that form the array. Instead, only the loaded coils of the parallel array transmit significant part of total transmitted power to the receiver. Such adaptive behavior enables superior power, size and cost efficiency then other solutions since it does not need to use complex detection circuitry to find the location of the load. The performance of the proposed structure is verified by measurement results. Natural load detection and covering 4 times bigger area than conventional topologies with a power transfer efficiency of 55% are the novelties of presented paper.

S-Band POSIX Device Drivers for RTEMS

Science.gov (United States)

Lux, James P.; Lang, Minh; Peters, Kenneth J.; Taylor, Gregory H.

2011-01-01

This is a set of POSIX device driver level abstractions in the RTEMS RTOS (Real-Time Executive for Multiprocessor Systems real-time operating system) to SBand radio hardware devices that have been instantiated in an FPGA (field-programmable gate array). These include A/D (analog-to-digital) sample capture, D/A (digital-to-analog) sample playback, PLL (phase-locked-loop) tuning, and PWM (pulse-width-modulation)-controlled gain. This software interfaces to Sband radio hardware in an attached Xilinx Virtex-2 FPGA. It uses plug-and-play device discovery to map memory to device IDs. Instead of interacting with hardware devices directly, using direct-memory mapped access at the application level, this driver provides an application programming interface (API) offering that easily uses standard POSIX function calls. This simplifies application programming, enables portability, and offers an additional level of protection to the hardware. There are three separate device drivers included in this package: sband_device (ADC capture and DAC playback), pll_device (RF front end PLL tuning), and pwm_device (RF front end AGC control).

Near Field and Far Field Effects in the Taguchi-Optimized Design of AN InP/GaAs-BASED Double Wafer-Fused Mqw Long-Wavelength Vertical-Cavity Surface-Emitting Laser

Science.gov (United States)

Menon, P. S.; Kandiah, K.; Mandeep, J. S.; Shaari, S.; Apte, P. R.

Long-wavelength VCSELs (LW-VCSEL) operating in the 1.55 μm wavelength regime offer the advantages of low dispersion and optical loss in fiber optic transmission systems which are crucial in increasing data transmission speed and reducing implementation cost of fiber-to-the-home (FTTH) access networks. LW-VCSELs are attractive light sources because they offer unique features such as low power consumption, narrow beam divergence and ease of fabrication for two-dimensional arrays. This paper compares the near field and far field effects of the numerically investigated LW-VCSEL for various design parameters of the device. The optical intensity profile far from the device surface, in the Fraunhofer region, is important for the optical coupling of the laser with other optical components. The near field pattern is obtained from the structure output whereas the far-field pattern is essentially a two-dimensional fast Fourier Transform (FFT) of the near-field pattern. Design parameters such as the number of wells in the multi-quantum-well (MQW) region, the thickness of the MQW and the effect of using Taguchi's orthogonal array method to optimize the device design parameters on the near/far field patterns are evaluated in this paper. We have successfully increased the peak lasing power from an initial 4.84 mW to 12.38 mW at a bias voltage of 2 V and optical wavelength of 1.55 μm using Taguchi's orthogonal array. As a result of the Taguchi optimization and fine tuning, the device threshold current is found to increase along with a slight decrease in the modulation speed due to increased device widths.

Virtual electrodes for high-density electrode arrays

Science.gov (United States)

Cela, Carlos J.; Lazzi, Gianluca

2015-10-13

The present embodiments are directed to implantable electrode arrays having virtual electrodes. The virtual electrodes may improve the resolution of the implantable electrode array without the burden of corresponding complexity of electronic circuitry and wiring. In a particular embodiment, a virtual electrode may include one or more passive elements to help steer current to a specific location between the active electrodes. For example, a passive element may be a metalized layer on a substrate that is adjacent to, but not directly connected to an active electrode. In certain embodiments, an active electrode may be directly coupled to a power source via a conductive connection. Beneficially, the passive elements may help to increase the overall resolution of the implantable array by providing additional stimulation points without requiring additional wiring or driver circuitry for the passive elements.

Experimental demonstration of 56 Gbit/s PAM-4 over 15 km and 84 Gbit/s PAM-4 over 1 km SSMF at 1525 nm using a 25G VCSEL

DEFF Research Database (Denmark)

Eiselt, Nicklas; Griesser, Helmut; Wei, Jinlong

2016-01-01

Record 28-GBd PAM-4 transmission over 15 km SSMF and 42-GBd PAM-4 over 1 km SSMF using a low-power 25G VCSEL are demonstrated at 1525 nm without optical dispersion compensation and only simple transceiver DSPs....

FIVE PHASE PENTAGON HYBRID STEPPER MOTOR INTELLIGENT HALF/FULL DRIVER

Directory of Open Access Journals (Sweden)

Alexandru Morar

2017-06-01

Full Text Available Stepper motors are very well suited for positioning applications since they can achieve very good positional accuracy without complicated feedback loops associated with servo systems. In this paper, an intelligent five-phase stepper motor driver of business card size proposed. Constant current chopping technique was applied for the purposes of high torque, high velocity and high efficiency. The driver was designed to drive a middle-sized hybrid stepper motor with wire current rating from 0.4 to 1.5A. An up-to-dated translator of five-phase stepping motor was used to drive the gates of N- channel MOSFET array. The resolution in full/half mode is 0.72/0.36 degrees/step. Moreover, an automatic power down circuit was used to limit the power consuming as the motor stops. Additionally, a self-testing program embedded in a 80C31-CPU (PCL838 can self-test whether the driver is normal or not. This embedded program including linear acceleration and deceleration routines also can serve as a positioning controller. The dimension of this driver is approximate 70x65x35 millimeters, which is smaller than a business card. Experimental results demonstrate that the responses of the driver can reach 60 kilo pulses per second

Characterization of InAs quantum wires on (001) InP: toward the realization of VCSEL structures with a stabilized polarization

OpenAIRE

Lamy , Jean-Michel; Levallois , Christophe; Nakkar , Abdulhadi; Caroff , Philippe; Paranthoen , Cyril; Dehaese , Olivier; Le Corre , Alain; Ramdane , Abderrahim; Loualiche , Slimane

2006-01-01

International audience; We propose a new type of long-wavelength vertical cavity surface emitting laser (VCSEL) which consists of quantum wires (QWires) layers of InAs/InGaAsP grown on InP(001) and dielectrics Bragg mirrors, in order to control the in plane polarization of output power. QWires and quantum wells growth are performed by molecular beam epitaxy. QWires present a strong photoluminescence dependence to the polarization in contrast to the quantum wells, a polarization rate of 33% is...

Design of a 5-MA 100-ns linear-transformer-driver accelerator for wire array Z-pinch experiments

Directory of Open Access Journals (Sweden)

Zhou Lin

2016-03-01

Full Text Available The linear-transformer-driver (LTD is a recently developed pulsed-power technology that shows great promise for a number of applications. These include a Z-pinch-driven fission-fusion-hybrid reactor that is being developed by the Chinese Academy of Engineering Physics. In support of the reactor development effort, we are planning to build an LTD-based accelerator that is optimized for driving wire-array Z-pinch loads. The accelerator comprises six modules in parallel, each of which has eight series 0.8-MA LTD cavities in a voltage-adder configuration. Vacuum transmission lines are used from the interior of the adder to the central vacuum chamber where the load is placed. Thus the traditional stack-flashover problem is eliminated. The machine is 3.2 m tall and 12 m in outer diameter including supports. A prototype cavity was built and tested for more than 6000 shots intermittently at a repetition rate of 0.1 Hz. A novel trigger, in which only one input trigger pulse is needed by utilizing an internal trigger brick, was developed and successfully verified in these shots. A full circuit modeling was conducted for the accelerator. The simulation result shows that a current pulse rising to 5.2 MA in 91 ns (10%–90% can be delivered to the wire-array load, which is 1.5 cm in height, 1.2 cm in initial radius, and 1 mg in mass. The maximum implosion velocity of the load is 32  cm/μs when compressed to 0.1 of the initial radius. The maximum kinetic energy is 78 kJ, which is 11.7% of the electric energy stored in the capacitors. This accelerator is supposed to enable a radiation energy efficiency of 20%–30%, providing a high efficient facility for research on the fast Z pinch and technologies for repetition-rate-operated accelerators.

Performance analysis of communication links based on VCSEL and silicon photonics technology for high-capacity data-intensive scenario.

Science.gov (United States)

Boletti, A; Boffi, P; Martelli, P; Ferrario, M; Martinelli, M

2015-01-26

To face the increased demand for bandwidth, cost-effectiveness and simplicity of future Ethernet data communications, a comparison between two different solutions based on directly-modulated VCSEL sources and Silicon Photonics technologies is carried out. Also by exploiting 4-PAM modulation, the transmission of 50-Gb/s and beyond capacity per channel is analyzed by means of BER performance. Applications for optical backplane, very short reach and in case of client-optics networks and intra and inter massive data centers communications (up to 10 km) are taken into account. A comparative analysis based on the power consumption is also proposed.

Ultra-thin silicon (UTSi) on insulator CMOS transceiver and time-division multiplexed switch chips for smart pixel integration

Science.gov (United States)

Zhang, Liping; Sawchuk, Alexander A.

2001-12-01

We describe the design, fabrication and functionality of two different 0.5 micron CMOS optoelectronic integrated circuit (OEIC) chips based on the Peregrine Semiconductor Ultra-Thin Silicon on insulator technology. The Peregrine UTSi silicon- on-sapphire (SOS) technology is a member of the silicon-on- insulator (SOI) family. The low-loss synthetic sapphire substrate is optically transparent and has good thermal conductivity and coefficient of thermal expansion properties, which meet the requirements for flip-chip bonding of VCSELs and other optoelectronic input-output components. One chip contains transceiver and network components, including four channel high-speed CMOS transceiver modules, pseudo-random bit stream (PRBS) generators, a voltage controlled oscillator (VCO) and other test circuits. The transceiver chips can operate in both self-testing mode and networking mode. An on- chip clock and true-single-phase-clock (TSPC) D-flip-flop have been designed to generate a PRBS at over 2.5 Gb/s for the high-speed transceiver arrays to operate in self-testing mode. In the networking mode, an even number of transceiver chips forms a ring network through free-space or fiber ribbon interconnections. The second chip contains four channel optical time-division multiplex (TDM) switches, optical transceiver arrays, an active pixel detector and additional test devices. The eventual applications of these chips will require monolithic OEICs with integrated optical input and output. After fabrication and testing, the CMOS transceiver array dies will be packaged with 850 nm vertical cavity surface emitting lasers (VCSELs), and metal-semiconductor- metal (MSM) or GaAs p-i-n detector die arrays to achieve high- speed optical interconnections. The hybrid technique could be either wire bonding or flip-chip bonding of the CMOS SOS smart-pixel arrays with arrays of VCSELs and photodetectors onto an optoelectronic chip carrier as a multi-chip module (MCM).

CCD and IR array controllers

Science.gov (United States)

Leach, Robert W.; Low, Frank J.

2000-08-01

A family of controllers has bene developed that is powerful and flexible enough to operate a wide range of CCD and IR focal plane arrays in a variety of ground-based applications. These include fast readout of small CCD and IR arrays for adaptive optics applications, slow readout of large CCD and IR mosaics, and single CCD and IR array operation at low background/low noise regimes as well as high background/high speed regimes. The CCD and IR controllers have a common digital core based on user- programmable digital signal processors that are used to generate the array clocking and signal processing signals customized for each application. A fiber optic link passes image data and commands to VME or PCI interface boards resident in a host computer to the controller. CCD signal processing is done with a dual slope integrator operating at speeds of up to one Megapixel per second per channel. Signal processing of IR arrays is done either with a dual channel video processor or a four channel video processor that has built-in image memory and a coadder to 32-bit precision for operating high background arrays. Recent developments underway include the implementation of a fast fiber optic data link operating at a speed of 12.5 Megapixels per second for fast image transfer from the controller to the host computer, and supporting image acquisition software and device drivers for the PCI interface board for the Sun Solaris, Linux and Windows 2000 operating systems.

Removing Background Noise with Phased Array Signal Processing

Science.gov (United States)

Podboy, Gary; Stephens, David

2015-01-01

Preliminary results are presented from a test conducted to determine how well microphone phased array processing software could pull an acoustic signal out of background noise. The array consisted of 24 microphones in an aerodynamic fairing designed to be mounted in-flow. The processing was conducted using Functional Beam forming software developed by Optinav combined with cross spectral matrix subtraction. The test was conducted in the free-jet of the Nozzle Acoustic Test Rig at NASA GRC. The background noise was produced by the interaction of the free-jet flow with the solid surfaces in the flow. The acoustic signals were produced by acoustic drivers. The results show that the phased array processing was able to pull the acoustic signal out of the background noise provided the signal was no more than 20 dB below the background noise level measured using a conventional single microphone equipped with an aerodynamic forebody.

High performance organic transistor active-matrix driver developed on paper substrate

Science.gov (United States)

Peng, Boyu; Ren, Xiaochen; Wang, Zongrong; Wang, Xinyu; Roberts, Robert C.; Chan, Paddy K. L.

2014-09-01

The fabrication of electronic circuits on unconventional substrates largely broadens their application areas. For example, green electronics achieved through utilization of biodegradable or recyclable substrates, can mitigate the solid waste problems that arise at the end of their lifespan. Here, we combine screen-printing, high precision laser drilling and thermal evaporation, to fabricate organic field effect transistor (OFET) active-matrix (AM) arrays onto standard printer paper. The devices show a mobility and on/off ratio as high as 0.56 cm2V-1s-1 and 109 respectively. Small electrode overlap gives rise to a cut-off frequency of 39 kHz, which supports that our AM array is suitable for novel practical applications. We demonstrate an 8 × 8 AM light emitting diode (LED) driver with programmable scanning and information display functions. The AM array structure has excellent potential for scaling up.

Examination of Supplemental Driver Training and Online Basic Driver Education

Science.gov (United States)

2012-06-01

This report describes supplemental driver training programs and online basic driver education. It coves supplemental driver training that : focused on knowledge and skills beyond those normally found in traditional driver education delivered in the U...

Are professional drivers less sleepy than non-professional drivers?

Science.gov (United States)

Anund, Anna; Ahlström, Christer; Fors, Carina; Åkerstedt, Torbjörn

2018-01-01

Objective It is generally believed that professional drivers can manage quite severe fatigue before routine driving performance is affected. In addition, there are results indicating that professional drivers can adapt to prolonged night shifts and may be able to learn to drive without decreased performance under high levels of sleepiness. However, very little research has been conducted to compare professionals and non-professionals when controlling for time driven and time of day. Method The aim of this study was to use a driving simulator to investigate whether professional drivers are more resistant to sleep deprivation than non-professional drivers. Differences in the development of sleepiness (self-reported, physiological and behavioral) during driving was investigated in 11 young professional and 15 non-professional drivers. Results Professional drivers self-reported significantly lower sleepiness while driving a simulator than non-professional drivers. In contradiction, they showed longer blink durations and more line crossings, both of which are indicators of sleepiness. They also drove faster. The reason for the discrepancy in the relation between the different sleepiness indicators for the two groups could be due to more experience to sleepiness among the professional drivers or possibly to the faster speed, which might unconsciously have been used by the professionals to try to counteract sleepiness. Conclusion Professional drivers self-reported significantly lower sleepiness while driving a simulator than non-professional drivers. However, they showed longer blink durations and more line crossings, both of which are indicators of sleepiness, and they drove faster.

Design considerations on a sparse array antenna for Ka-band spaceborne SAR applications

NARCIS (Netherlands)

Jacobs, S.; Bekers, D.; Monni, S.; Otten, M.; Van Rossum, W.; Gerini, G.; Germani, C.; Fortini, D.; Toso, G.

2015-01-01

This contribution addresses the problem of designing a sparse active array antenna for spaceborne SAR applications at Ka-band. The main driver for the design is limiting the recurring manufacturing costs associated to the number of active modules, while preserving main performance and insuring a

A new linear inductive voltage adder driver for the Saturn Accelerator

International Nuclear Information System (INIS)

Mazarakis, M.G.; Spielman, R.B.; Struve, K.W.; Long, F.W.

2000-01-01

Saturn is a dual-purpose accelerator. It can be operated as a large-area flash x-ray source for simulation testing or as a Z-pinch driver especially for K-line x-ray production. In the first mode, the accelerator is fitted with three concentric-ring 2-MV electron diodes, while in the Z-pinch mode the current of all the modules is combined via a post-hole convolute arrangement and driven through a cylindrical array of very fine wires. We present here a point design for a new Saturn class driver based on a number of linear inductive voltage adders connected in parallel. A technology recently implemented at the Institute of High Current Electronics in Tomsk (Russia) is being utilized. In the present design we eliminate Marx generators and pulse-forming networks. Each inductive voltage adder cavity is directly fed by a number of fast 100-kV small-size capacitors arranged in a circular array around each accelerating gap. The number of capacitors connected in parallel to each cavity defines the total maximum current. By selecting low inductance switches, voltage pulses as short as 30-50-ns FWHM can be directly achieved. The voltage of each stage is low (100-200 kv). Many stages are required to achieve multi-megavolt accelerator output. However, since the length of each stage is very short (4-10 cm), accelerating gradients of higher than 1 MV/m can easily be obtained. The proposed new driver will be capable of delivering pulses of 15-MA, 36-TW, 1.2-MJ to the diode load, with a peak voltage of -2.2 MV and FWHM of 40-ns. And although its performance will exceed the presently utilized driver, its size and cost could be much smaller (approximately1/3). In addition, no liquid dielectrics like oil or deionized water will be required. Even elimination of ferromagnetic material (by using air-core cavities) is a possibility

DRIVER INATTENTION

Directory of Open Access Journals (Sweden)

Richard TAY

2004-01-01

Full Text Available Driver inattention, especially driver distraction, is an extremely influential but generally neglected contributing factor of road crashes. This paper explores some of the common behaviours associated with several common forms of driver inattention, with respect to their perceived crash risks, rates of self-reported behaviours and whether drivers regulate such behaviours depending on the road and traffic environment, and provides some policy recommendations to address issues raised.

Development of Superconducting Focusing Quadrupoles for Heavy Ion Drivers

Energy Technology Data Exchange (ETDEWEB)

Martovetsky, N; Manahan, R; Lietzke, A F

2001-09-10

Heavy Ion Fusion (HIF) is exploring a promising path to a practical inertial-confinement fusion reactor. The associated heavy ion driver will require a large number of focusing quadrupole magnets. A concept for a superconducting quadrupole array, using many simple racetrack coils, was developed at LLNL. Two, single-bore quadrupole prototypes of the same design, with distinctly different conductor, were designed, built, and tested. Both prototypes reached their short sample currents with little or no training. Magnet design, and test results, are presented and discussed.

Driving fatigue in professional drivers: a survey of truck and taxi drivers.

Science.gov (United States)

Meng, Fanxing; Li, Shuling; Cao, Lingzhi; Li, Musen; Peng, Qijia; Wang, Chunhui; Zhang, Wei

2015-01-01

Fatigue among truck drivers has been studied extensively; however, less is known regarding the fatigue experience of taxi drivers in heavily populated metropolitan areas. This study aimed to compare the differences and similarities between truck and taxi driver fatigue to provide implications for the fatigue management and education of professional drivers. A sample of 274 truck drivers and 286 taxi drivers in Beijing was surveyed via a questionnaire, which included items regarding work characteristics, fatigue experience, accident information, attitude toward fatigue, and methods of counteracting fatigue. Driver fatigue was prevalent among professional drivers, and it was even more serious for taxi drivers. Taxi drivers reported more frequent fatigue experiences and were involved in more accidents. Among the contributing factors to fatigue, prolonged driving time was the most important factor identified by both driver groups. Importantly, the reason for the engagement in prolonged driving was neither due to the lack of awareness concerning the serious outcome of fatigue driving nor because of their poor detection of fatigue. The most probable reason was the optimism bias, as a result of which these professional drivers thought that fatigue was more serious for other drivers than for themselves, and they thought that they were effective in counteracting the effect of fatigue on their driving performance. Moreover, truck drivers tended to employ methods that require stopping to counteract fatigue, whereas taxi drivers preferred methods that were simultaneous with driving. Although both driver groups considered taking a nap as one of the most effective means to address fatigue, this method was not commonly used. Interestingly, these drivers were aware that the methods they frequently used were not the most effective means to counteract fatigue. This study provides knowledge on truck and taxi drivers' characteristics in fatigue experience, fatigue attitude, and

Square pulse linear transformer driver

Directory of Open Access Journals (Sweden)

A. A. Kim

2012-04-01

Full Text Available The linear transformer driver (LTD technological approach can result in relatively compact devices that can deliver fast, high current, and high-voltage pulses straight out of the LTD cavity without any complicated pulse forming and pulse compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. The usual LTD architecture [A. A. Kim, M. G. Mazarakis, V. A. Sinebryukhov, B. M. Kovalchuk, V. A. Vizir, S. N Volkov, F. Bayol, A. N. Bastrikov, V. G. Durakov, S. V. Frolov, V. M. Alexeenko, D. H. McDaniel, W. E. Fowler, K. LeCheen, C. Olson, W. A. Stygar, K. W. Struve, J. Porter, and R. M. Gilgenbach, Phys. Rev. ST Accel. Beams 12, 050402 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050402; M. G. Mazarakis, W. E. Fowler, A. A. Kim, V. A. Sinebryukhov, S. T. Rogowski, R. A. Sharpe, D. H. McDaniel, C. L. Olson, J. L. Porter, K. W. Struve, W. A. Stygar, and J. R. Woodworth, Phys. Rev. ST Accel. Beams 12, 050401 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050401] provides sine shaped output pulses that may not be well suited for some applications like z-pinch drivers, flash radiography, high power microwaves, etc. A more suitable power pulse would have a flat or trapezoidal (rising or falling top. In this paper, we present the design and first test results of an LTD cavity that generates such a type of output pulse by including within its circular array a number of third harmonic bricks in addition to the main bricks. A voltage adder made out of a square pulse cavity linear array will produce the same shape output pulses provided that the timing of each cavity is synchronized with the propagation of the electromagnetic pulse.

Volumetric cutaneous microangiography of human skin in vivo by VCSEL swept-source optical coherence tomography

International Nuclear Information System (INIS)

Woo June Choi; Wang, R K

2014-01-01

We demonstrate volumetric cutaneous microangiography of the human skin in vivo that utilises 1.3-μm high-speed sweptsource optical coherence tomography (SS-OCT). The swept source is based on a micro-electro-mechanical (MEMS)-tunable vertical cavity surface emission laser (VCSEL) that is advantageous in terms of long coherence length over 50 mm and 100 nm spectral bandwidth, which enables the visualisation of microstructures within a few mm from the skin surface. We show that the skin microvasculature can be delineated in 3D SS-OCT images using ultrahigh-sensitive optical microangiography (UHS-OMAG) with a correlation mapping mask, providing a contrast enhanced blood perfusion map with capillary flow sensitivity. 3D microangiograms of a healthy human finger are shown with distinct cutaneous vessel architectures from different dermal layers and even within hypodermis. These findings suggest that the OCT microangiography could be a beneficial biomedical assay to assess cutaneous vascular functions in clinic. (laser biophotonics)

Volumetric cutaneous microangiography of human skin in vivo by VCSEL swept-source optical coherence tomography

Energy Technology Data Exchange (ETDEWEB)

Woo June Choi; Wang, R K [University of Washington, Department of Bioengineering, Seattle, Washington 98195 (United States)

2014-08-31

We demonstrate volumetric cutaneous microangiography of the human skin in vivo that utilises 1.3-μm high-speed sweptsource optical coherence tomography (SS-OCT). The swept source is based on a micro-electro-mechanical (MEMS)-tunable vertical cavity surface emission laser (VCSEL) that is advantageous in terms of long coherence length over 50 mm and 100 nm spectral bandwidth, which enables the visualisation of microstructures within a few mm from the skin surface. We show that the skin microvasculature can be delineated in 3D SS-OCT images using ultrahigh-sensitive optical microangiography (UHS-OMAG) with a correlation mapping mask, providing a contrast enhanced blood perfusion map with capillary flow sensitivity. 3D microangiograms of a healthy human finger are shown with distinct cutaneous vessel architectures from different dermal layers and even within hypodermis. These findings suggest that the OCT microangiography could be a beneficial biomedical assay to assess cutaneous vascular functions in clinic. (laser biophotonics)

Comparison of Mesa and Device Diameter Variation in Double Wafer-Fused Multi Quantum-Well, Long-Wavelength, Vertical Cavity Surface Emitting Lasers

International Nuclear Information System (INIS)

Menon, P.S.; Kandiah, K.; Burhanuddin Yeop Majlis; Shaari, S.

2011-01-01

Long-wavelength vertical-cavity surface-emitting lasers (LW-VCSELs) have profound advantages compared to traditional edge-emitting lasers offering improved properties with respect to mode selectivity, fibre coupling, threshold currents and integration into 2D arrays or with other electronic devices. Its commercialization is gaining momentum as the local and access network in optical communication system expand. Numerical modeling of LW-VCSEL utilizing wafer-fused InP-based multi-quantum wells (MQW) and GaAs-based distributed Bragg reflectors (DBRs) is presented in this paper. Emphasis is on the device and mesa/pillar diameter design parameter comparison and its effect on the device characteristics. (author)

Locomotor diseases among male long-haul truck drivers and other professional drivers

DEFF Research Database (Denmark)

Jensen, Anker; Kaerlev, Linda; Tüchsen, Finn

2007-01-01

-249) and for other truck drivers (SHR: 130, 95% CI: 108-156) compared to bus drivers (SHR: 110, 95% CI: 79-149). All drivers had high SHR for lesions of the ulnar nerve (SHR: 159, 95% CI: 119-207), especially bus drivers (SHR: 197, 95% CI: 116-311). Long-haul truck drivers had high SHRs for synovitis and bursitis...

Room-temperature continuous-wave operation of the In(Ga)As/GaAs quantum-dot VCSELs for the 1.3 µm optical-fibre communication

International Nuclear Information System (INIS)

Xu Dawei; Tong Cunzhu; Yoon, Soon Fatt; Fan Weijun; Zhang, Dao Hua; Wasiak, Michał; Piskorski, Łukasz; Gutowski, Krzysztof; Sarzała, Robert P; Nakwaski, Włodzimierz

2009-01-01

Efficient room-temperature (RT) continuous-wave (CW) lasing operation of the 1.3 µm MBE (molecular-beam epitaxy) In(Ga)As/GaAs quantum-dot (QD) top-emitting oxide-confined vertical-cavity surface-emitting diode lasers (VCSELs) for the second-generation optical-fibre communication has been achieved. In their design, a concept of a QD inside a quantum well (QW) has been utilized. The proposed In(Ga)As/GaAs QD active region is composed of five groups of three 8 nm In 0.15 Ga 0.85 As QWs, each containing one InAs QD sheet layer. In each group located close to successive anti-node positions of the optical standing wave within the 3λ cavity, QWs are separated by 32 nm GaAs barriers. Besides, at both active-region edges, additional single InGaAs QWs are located containing single QD layers. For the 10 µm diameter QD VCSELs, the RT CW threshold current of only 6.2 mA (7.9 kA cm −2 ), differential efficiency of 0.11 W A −1 and the maximal output power of 0.85 mW have been recorded. The experimental characteristics are in excellent agreement with theoretical ones obtained using the optical-electrical-thermal-recombination self-consistent computer model. According to this, for the 10 µm devices, the fundamental linearly polarized LP 01 mode remains the dominating one up to the current of 9.1 mA. The lowest RT CW lasing threshold below 5 mA is expected for 6 µm devices

Driver style and driver skill – Clustering sub-groups of drivers differing in their potential danger in traffic

DEFF Research Database (Denmark)

Martinussen, Laila Marianne; Møller, Mette; Prato, Carlo Giacomo

The Driver Behavior Questionnaire (DBQ) and the Driver Skill Inventory (DSI) are two of the most frequently used measures of self-reported driving style and driving skill. The motivation behind the present study was to test drivers’ consistency or judgment of their own self-reported driving ability...... based on a combined use of the DBQ and the DSI. Moreover, the joint use of the two instruments was applied to identify sub-groups of drivers that differ in their potential danger in traffic (as measured by frequency of aberrant driving behaviors and level of driving skills), as well as to test whether...... the sub-groups of drivers differed in characteristics such as age, gender, annual mileage and accident involvement. 3908 drivers aged 18–84 participated in the survey. The results suggested that the drivers are consistent in their reporting of driving ability, as the self-reported driving skill level...

Kin-Driver: a database of driver mutations in protein kinases.

Science.gov (United States)

Simonetti, Franco L; Tornador, Cristian; Nabau-Moretó, Nuria; Molina-Vila, Miguel A; Marino-Buslje, Cristina

2014-01-01

Somatic mutations in protein kinases (PKs) are frequent driver events in many human tumors, while germ-line mutations are associated with hereditary diseases. Here we present Kin-driver, the first database that compiles driver mutations in PKs with experimental evidence demonstrating their functional role. Kin-driver is a manual expert-curated database that pays special attention to activating mutations (AMs) and can serve as a validation set to develop new generation tools focused on the prediction of gain-of-function driver mutations. It also offers an easy and intuitive environment to facilitate the visualization and analysis of mutations in PKs. Because all mutations are mapped onto a multiple sequence alignment, analogue positions between kinases can be identified and tentative new mutations can be proposed for studying by transferring annotation. Finally, our database can also be of use to clinical and translational laboratories, helping them to identify uncommon AMs that can correlate with response to new antitumor drugs. The website was developed using PHP and JavaScript, which are supported by all major browsers; the database was built using MySQL server. Kin-driver is available at: http://kin-driver.leloir.org.ar/ © The Author(s) 2014. Published by Oxford University Press.

Driver style and driver skills – clustering drivers differing in their potential danger in traffic

DEFF Research Database (Denmark)

Martinussen, Laila Marianne; Møller, Mette; Prato, Carlo Giacomo

The Driver Behavior Questionnaire (DBQ) and the Driver Skill Inventory (DSI) are two of the most frequently used measures of driving style and driving skill. The motivation behind the present study was to test drivers’ insight into their own driving ability based on a combined use of the DBQ......, annual mileage and accident involvement. 3908 drivers aged 18–84 participated in the survey. The results suggested that the drivers have good insight into their own driving ability, as the driving skill level mirrored the frequency of aberrant driving behaviors. K-means cluster analysis revealed four...... distinct clusters that differed in the frequency of aberrant driving behavior and driving skills, as well as individual characteristics and driving related factors such as annual mileage, accident frequency and number of tickets and fines. Thus, two sub-groups were identified as more unsafe than the two...

Schoolbus driver performance can be improved with driver training ...

African Journals Online (AJOL)

and compares the school transport driver performance with that of general motorists. Despite concerns that ... To compare Safe Travel to School Programme driver safety perfor- .... The SA government has recognised the challenges faced with.

Solid state laser driver for an ICF reactor

International Nuclear Information System (INIS)

Krupke, W.F.

1988-01-01

A conceptual design is presented of the main power amplifier of a multi-beamline, multi-megawatt solid state ICF reactor driver. Simultaneous achievement of useful beam quality and high average power is achieved by a proper choice of amplifier geometry. An amplifier beamline consists of a sequence of face-pumped rectangular slab gain elements, oriented at the Brewster angle relative to the beamline axis, and cooled on their large faces by helium gas that is flowing subsonically. The infrared amplifier output radiation is shifted to an appropriately short wavelength ( 10% (including all flow cooling input power) when the amplifiers are pumped by efficient high-power AlGaAs semiconductor laser diode arrays. 11 refs., 3 figs., 7 tabs

Special design issues. Ion beam driver-reaction chamber interfaces

International Nuclear Information System (INIS)

Moir, R.W.; Peterson, R.R.; Kessler, G.

1995-01-01

Design issues of the interface between ion beam drivers and the reaction chamber for heavy ion beam and light ion beam inertial fusion drivers are discussed. The interface must provide for radiation protection of final focusing magnets, pumping of evaporated material and non-condensable gas that enter the beam ports, thermal insulation, heat removal, a.o.. Beam ports and focal magnets must be protected by neutronically thick shielding between the beam path and the magnet conductor. The required thickness of the shielding determines the minimum spacing between individual beams in a cluster of beams. The cone angle of this cluster can affect target performance. The beamlines are subjected to evaporated material, debris, and rapidly moving droplets. The reaction chambers used here are HYLIFE-II for indirect, HIBALL-II for direct drive. The light ion beam interface is based on the LIBRA and LIBRA-LiTE studies. In the case of HYLIFE-II, liquid jets must be demonstrated with a thickness of 0.5 m and with an edge that comes to within 10 mm of the beam edges to protect the ports. Design of compact focal arrays with enough shielding to give magnets an adequate lifetime must be achieved. As shielding is added the size of the beam array will grow and the target will drop. For HIBALL neutron shielding of the focal magnets provides an adequate lifetime. Replaceable special INPORT units will have to be developed in the region of the beam ports. For light ions transport issues have led to structures being placed close enough to the target that they experience a higher neutron damage rate and must be replaced once or twice a year, which would require remote maintenance. Light ion concepts could greatly benefit from a self-pinched transport scheme, though the details are unclear and the effect on availability is uncertain. Light and heavy ions have similar problems in keeping the gas in the drivers at a low density. Both will require active means to preserve this low density, while

Phase Locking of Laser Diode Array by Using an Off-Axis External Talbot Cavity

International Nuclear Information System (INIS)

Su Zhou-Ping; Zhu Zhuo-Wei; Que Li-Zhi; Zhu Yun; Ji Zhi-Cheng

2012-01-01

Phase locking of a laser diode array is demonstrated experimentally by using an off-axis external Talbot cavity with a feedback plane mirror. Due to good spatial mode discrimination, the cavity does not need a spatial filter. By employing the cavity, a clear and stable far-field interference pattern can be observed when the driver current is less than 14 A. In addition, the spectral line width can be reduced to 0.8 nm. The slope efficiency of the phase-locked laser diode array is about 0.62 W/A. (fundamental areas of phenomenology(including applications))

Developing infrared array controller with software real time operating system

Science.gov (United States)

Sako, Shigeyuki; Miyata, Takashi; Nakamura, Tomohiko; Motohara, Kentaro; Uchimoto, Yuka Katsuno; Onaka, Takashi; Kataza, Hirokazu

2008-07-01

Real-time capabilities are required for a controller of a large format array to reduce a dead-time attributed by readout and data transfer. The real-time processing has been achieved by dedicated processors including DSP, CPLD, and FPGA devices. However, the dedicated processors have problems with memory resources, inflexibility, and high cost. Meanwhile, a recent PC has sufficient resources of CPUs and memories to control the infrared array and to process a large amount of frame data in real-time. In this study, we have developed an infrared array controller with a software real-time operating system (RTOS) instead of the dedicated processors. A Linux PC equipped with a RTAI extension and a dual-core CPU is used as a main computer, and one of the CPU cores is allocated to the real-time processing. A digital I/O board with DMA functions is used for an I/O interface. The signal-processing cores are integrated in the OS kernel as a real-time driver module, which is composed of two virtual devices of the clock processor and the frame processor tasks. The array controller with the RTOS realizes complicated operations easily, flexibly, and at a low cost.

Interferometric characterization of laboratory plasma astrophysical jets produced by a 1-μs pulsed power driver

International Nuclear Information System (INIS)

Plouhinec, Damien; Zucchini, Frederic; Loyen, Arnaud; Sol, David; Combes, Philippe; Grunenwald, Julien; Hammer, David A.

2014-01-01

A high current driver based on microsecond LTD technology has been used to perform laboratory plasma astrophysics studies using a conical wire array load coupled a 950 kA, 1.2-μs pulsed power generator. A plasma jet is generated as a result of the on-axis shock formed by the ablation streams from the wires of a conical tungsten wire-array load together with conservation of the axial momentum. The aim of this paper is to produce a scaled-down laboratory simulation of astrophysical Herbig-Haro plasma jets occurring during star formation along with some of their interactions with the interstellar medium, such as a cross wind. Due to the relatively long duration of the current pulse delivered by the driver, the jet develops on a 2-μs timescale and grows up to 100 mm. A time-resolved laser interferometer has been fielded to measure the plasma areal electron density as a function of time in and around the plasma jets. The setup consists of a continuous diode-pumped solid state laser (5 W-532 nm), a Mach-Zehnder interferometer and fast gated visible multi frame camera. (authors)

Negativity Bias in Dangerous Drivers.

Directory of Open Access Journals (Sweden)

Jing Chai

Full Text Available The behavioral and cognitive characteristics of dangerous drivers differ significantly from those of safe drivers. However, differences in emotional information processing have seldom been investigated. Previous studies have revealed that drivers with higher anger/anxiety trait scores are more likely to be involved in crashes and that individuals with higher anger traits exhibit stronger negativity biases when processing emotions compared with control groups. However, researchers have not explored the relationship between emotional information processing and driving behavior. In this study, we examined the emotional information processing differences between dangerous drivers and safe drivers. Thirty-eight non-professional drivers were divided into two groups according to the penalty points that they had accrued for traffic violations: 15 drivers with 6 or more points were included in the dangerous driver group, and 23 drivers with 3 or fewer points were included in the safe driver group. The emotional Stroop task was used to measure negativity biases, and both behavioral and electroencephalograph data were recorded. The behavioral results revealed stronger negativity biases in the dangerous drivers than in the safe drivers. The bias score was correlated with self-reported dangerous driving behavior. Drivers with strong negativity biases reported having been involved in mores crashes compared with the less-biased drivers. The event-related potentials (ERPs revealed that the dangerous drivers exhibited reduced P3 components when responding to negative stimuli, suggesting decreased inhibitory control of information that is task-irrelevant but emotionally salient. The influence of negativity bias provides one possible explanation of the effects of individual differences on dangerous driving behavior and traffic crashes.

Education and driver-training

Directory of Open Access Journals (Sweden)

Andrej Justinek

1999-12-01

Full Text Available The characteristics of the driver are manifested in his/her behaviour. For safe driving one must have a driver's knowledge. The contents of educational material are determined by law, and are both theoretical and practical, yet frequently they do not suffice to meet the requirements of safe driving. In this paper, the author suggests that, in the training of drivers, more educational elements should be included, such a would have  an effective influence on the driver's moti ves and attitudes. The driver's motives - which may result in incorrect driving­ are diverse: most often, the default is overspeeding, even though the drivers always over-estimate the potential time gain. In fact, over-fast driving is a way of satisfying other, different needs; and, above all, it is a form of compensation for unsettled life problems, and at the same time an indication of the driver's personal inability to cope with stress.

Reducing risky driver behaviour through the implementation of a driver risk management system

Directory of Open Access Journals (Sweden)

Rose Luke

2014-11-01

Full Text Available South Africa has one of the highest incidences of road accidents in the world. Most accidents are avoidable and are caused by driver behaviour and errors. The purpose of this article was to identify the riskiest driver behaviours in commercial fleets in South Africa, to determine the business impact of such behaviour, to establish a framework for the management of risky driver behaviour and to test the framework by applying a leading commercial driver behaviour management system as a case study. The case study comprised three South African commercial fleets. Using data from these fleets, critical incident triangles were used to determine the ratio data of risky driver behaviour to near-collisions and collisions. Based on managing the riskiest driver behaviours as causes of more serious incidents and accidents, the results indicated that through the implementation of an effective driver risk management system, risky incidents were significantly reduced.

Assessing drivers' response during automated driver support system failures with non-driving tasks.

Science.gov (United States)

Shen, Sijun; Neyens, David M

2017-06-01

With the increase in automated driver support systems, drivers are shifting from operating their vehicles to supervising their automation. As a result, it is important to understand how drivers interact with these automated systems and evaluate their effect on driver responses to safety critical events. This study aimed to identify how drivers responded when experiencing a safety critical event in automated vehicles while also engaged in non-driving tasks. In total 48 participants were included in this driving simulator study with two levels of automated driving: (a) driving with no automation and (b) driving with adaptive cruise control (ACC) and lane keeping (LK) systems engaged; and also two levels of a non-driving task (a) watching a movie or (b) no non-driving task. In addition to driving performance measures, non-driving task performance and the mean glance duration for the non-driving task were compared between the two levels of automated driving. Drivers using the automated systems responded worse than those manually driving in terms of reaction time, lane departure duration, and maximum steering wheel angle to an induced lane departure event. These results also found that non-driving tasks further impaired driver responses to a safety critical event in the automated system condition. In the automated driving condition, driver responses to the safety critical events were slower, especially when engaged in a non-driving task. Traditional driver performance variables may not necessarily effectively and accurately evaluate driver responses to events when supervising autonomous vehicle systems. Thus, it is important to develop and use appropriate variables to quantify drivers' performance under these conditions. Copyright © 2017 Elsevier Ltd and National Safety Council. All rights reserved.

PBFA Z: A 60-TW/5-MJ Z-pinch driver

International Nuclear Information System (INIS)

Spielman, R.B.; Deeney, C.; Chandler, G.A.; Douglas, M.R.; Fehl, D.L.; Matzen, M.K.; McDaniel, D.H.; Nash, T.J.; Porter, J.L.; Sanford, T.W.; Seamen, J.F.; Stygar, W.A.; Struve, K.W.; Breeze, S.P.; McGurn, J.S.; Torres, J.A.; Zagar, D.M.; Gilliland, T.L.; Jobe, D.O.; McKenney, J.L.; Mock, R.C.; Vargas, M.; Wagoner, T.; Peterson, D.L.

1997-01-01

PBFA Z, a new 60-TW/5-MJ electrical accelerator located at Sandia National Laboratories, is now the world's most powerful z-pinch driver. PBFA Z stores 11.4 MJ in its 36 Marx generators, couples 5 MJ into a 60-TW/105-ns FWHM pulse to the 120-mΩ water transmission lines, and delivers 3.0 MJ and 50 TW of electrical energy to the z-pinch load. Depending on load parameters, we attain peak load currents of 16-20 MA with a current rise time of ∼105ns with wire-array z-pinch loads. We have extended the x-ray performance of tungsten wire-array z pinches from earlier Saturn experiments. Using a 2-cm-radius, 2-cm-long tungsten wire array with 240, 7.5-μm diameter wires (4.1-mg mass), we achieved an x-ray power of 210 TW and an x-ray energy of 1.9 MJ. Preliminary spectral measurements suggest a mostly optically-thick, Planckian-like radiator below 1000 eV. Data indicate ∼100kJ of x rays radiated above 1000 eV. An intense z-pinch x-ray source with an overall coupling efficiency greater than 15% has been demonstrated. copyright 1997 American Institute of Physics

Modeling of Driver Steering Operations in Lateral Wind Disturbances toward Driver Assistance System

Science.gov (United States)

Kurata, Yoshinori; Wada, Takahiro; Kamiji, Norimasa; Doi, Shun'ichi

Disturbances decrease vehicle stability and increase driver's mental and physical workload. Especially unexpected disturbances such as lateral winds have severe effect on vehicle stability and driver's workload. This study aims at building a driver model of steering operations in lateral wind toward developing effective driver assistance system. First, the relationship between the driver's lateral motion and its reactive quick steering behavior is investigated using driving simulator with lateral 1dof motion. In the experiments, four different wind patterns are displayed by the simulator. As the results, strong correlation was found between the driver's head lateral jerk by the lateral disturbance and the angular acceleration of the steering wheel. Then, we build a mathematical model of driver's steering model from lateral disturbance input to steering torque of the reactive quick feed-forward steering based on the experimental results. Finally, validity of the proposed model is shown by comparing the steering torque of experimental results and that of simulation results.

Examination of supplemental driver training and online basic driver education courses : traffic tech.

Science.gov (United States)

2012-08-01

The first six months of unsupervised driving are the most : hazardous in a novice drivers driving experience. Most : States adopted graduated driver licensing (GDL) systems : to give novice drivers experience in a protective environment, : gradual...

An application of the driver behavior questionnaire to Chinese carless young drivers.

Science.gov (United States)

Zhang, Qian; Jiang, Zuhua; Zheng, Dongpeng; Wang, Yifan; Man, Dong

2013-01-01

Carless young drivers refers to those drivers aged between 18 and 25 years who have a driver's license but seldom have opportunities to practice their driving skills because they do not have their own cars. Due to China's lower private car ownership, many young drivers turn into carless young drivers after licensure, and the safety issue associated with them has become a matter of great concern in China. Because few studies have examined the driving behaviors of these drivers, this study aims to utilize the Driver Behavior Questionnaire (DBQ) to investigate the self-reported driving behaviors of Chinese carless young drivers. A total of 523 Chinese carless young drivers (214 females, 309 males) with an average age of 21.91 years completed a questionnaire including the 27-item DBQ and demographics. The data were first randomized into 2 subsamples for factor analysis and then combined together for the following analyses. Both an exploratory factor analysis (EFA, n = 174) and a confirmatory factor analysis (CFA, n = 349) were performed to investigate the factor structure of the DBQ. Correlation analysis was conducted to examine the relationships between the demographics and the DBQ scales' variables. Multivariate linear regression and logistic regression were performed to investigate the prediction of the DBQ scales and crash involvement in the previous year. The EFA produced a 4-factor structure identified as errors, violations, attention lapses, and memory lapses, and the CFA revealed a good model fit after the removal of one item with a low factor loading and the permission of the error covariance between some items. The Chinese carless young drivers reported a comparatively low level of aberrant driving behaviors. The 3 most frequently reported behaviors were all lapses and the 3 least were all violations. Gender was the only significant predictor of the 2 lapses scales and lifetime mileage was the only significant predictor of the violations scale. Only the

Planar wire array dynamics and radiation scaling at multi-MA levels on the Saturn pulsed power generator

International Nuclear Information System (INIS)

Chuvatin, Alexander S.; Vesey, Roger Alan; Waisman, Eduardo Mario; Esaulov, Andrey A.; Ampleford, David J.; Kantsyrev, Victor Leonidovich; Cuneo, Michael Edward; Rudakov, Leonid I.; Coverdale, Christine Anne; Jones, Brent Manley; Safronova, Alla S.; Jones, Michael C.

2008-01-01

Planar wire arrays are studied at 3-6 MA on the Saturn pulsed power generator as potential drivers of compact hohlraums for inertial confinement fusion studies. Comparison with zero-dimensional modeling suggests that there is significant trailing mass. The modeled energy coupled from the generator cannot generally explain the energy in the main x-ray pulse. Preliminary comparison at 1-6 MA indicates sub-quadratic scaling of x-ray power in a manner similar to compact cylindrical wire arrays. Time-resolved pinhole images are used to study the implosion dynamics

A short-pulse mode for the SPHINX LTD Z-pinch driver

Science.gov (United States)

D'Almeida, Thierry; Lassalle, Francis; Zucchini, Frederic; Loyen, Arnaud; Morell, Alain; Chuvatin, Alexander

2015-11-01

The SPHINX machine is a 6MA, 1 μs, LTD Z-pinch driver at CEA Gramat (France) and primarily used for studying radiation effects. Different power amplification concepts were examined in order to reduce the current rise time without modifying the generator discharge scheme, including the Dynamic Load Current Multiplier (DLCM) proposed by Chuvatin. A DLCM device, capable of shaping the current pulse without reducing the rise time, was developed at CEA. This device proved valuable for isentropic compression experiments in cylindrical geometry. Recently, we achieved a short pulse operation mode by inserting a vacuum closing switch between the DLCM and the load. The current rise time was reduced to ~300 ns. We explored the use of a reduced-height wire array for the Dynamic Flux Extruder in order to improve the wire array compression rate and increase the efficiency of the current transfer to the load. These developments are presented. Potential benefits of these developments for future Z pinch experiments are discussed.

Uniform irradiation of adjustable target spots in high-power laser driver

International Nuclear Information System (INIS)

Jiang Xiujuan; Li Jinghui; Li Huagang; Li Yang; Lin Zunqi

2011-01-01

For smoothing and shaping the on-target laser patterns flexibly in high-power laser drivers, a scheme has been developed that includes a zoom lens array and two-dimensional smoothing by spectral dispersion (SSD). The size of the target pattern can be controlled handily by adjusting the focal length of the zoom lens array, while the profile of the pattern can be shaped by fine tuning the distance between the target and the focal plane of the principal focusing lens. High-frequency stripes inside the pattern caused by beamlet interference are wiped off by spectral dispersion. Detailed simulations indicate that SSD works somewhat differently for spots of different sizes. For small spots, SSD mainly smooths the intensity modulation of low-to-middle spatial frequency, while for large spots, SSD sweeps the fine speckle structure to reduce nonuniformity of middle-to-high frequency. Spatial spectra of the target patterns are given and their uniformity is evaluated.

Characteristics of Chinese Driver Behavior

NARCIS (Netherlands)

Li, J.

2014-01-01

The high growth rate of vehicle ownership and many novel drivers in China determine the special features of Chinese driver behavior. This thesis introduces a comparative study on driver behavior by the analysis of saturation flow at urban intersections, Driver Behavior Questionnaire surveys, focus

Preliminary experimental results of tungsten wire-array Z-pinches on primary test stand

Energy Technology Data Exchange (ETDEWEB)

Huang, Xian-Bin; Zhou, Shao-Tong; Dan, Jia-Kun; Ren, Xiao-Dong, E-mail: amosrxd@163.com; Wang, Kun-Lun; Zhang, Si-Qun; Li, Jing; Xu, Qiang; Cai, Hong-Chun; Duan, Shu-Chao; Ouyang, Kai; Chen, Guang-Hua; Ji, Ce; Wei, Bing; Feng, Shu-Ping; Wang, Meng; Xie, Wei-Ping; Deng, Jian-Jun [Key Laboratory of Pulsed Power, Institute of Fluid Physics, China Academy of Engineering Physics, P.O. Box 919-108, Mianyang, Sichuan 621999 (China); Zhou, Xiu-Wen; Yang, Yi [Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-987, Mianyang, Sichuan 621999 (China)

2015-07-15

The Primary Test Stand (PTS) developed at the China Academy of Engineering Physics is a 20 TW pulsed power driver, which can deliver a ∼10 MA, 70 ns rise-time (10%–90%) current to a short-circuit load and has important applications in Z-pinch driven inertial confinement fusion and high energy density physics. Preliminary results of tungsten wire-array Z-pinch experiments on PTS are presented. The load geometries investigated include 15-mm-tall cylindrical single and nested arrays with diameter ranging from 13 mm to 30 mm, consisting of 132–300 tungsten wires with 5–10 μm in diameter. Multiple diagnostics were fielded to characterize the x-ray radiation from wire-array Z pinches. The x-ray peak power (∼50 TW) and total radiated energy (∼500 kJ) were obtained from a single 20-mm-diam array with 80-ns stagnation time. The highest x-ray peak power up to 80 TW with 2.4 ns FWHM was achieved by using a nested array with 20-mm outer diameter, and the total x-ray energy from the nested array is comparable to that of single array. Implosion velocity estimated from the time-resolved image measurement exceeds 30 cm/μs. The detailed experimental results and other findings are presented and discussed.

Acoustic Levitation With One Driver

Science.gov (United States)

Wang, T. G.; Rudnick, I.; Elleman, D. D.; Stoneburner, J. D.

1985-01-01

Report discusses acoustic levitation in rectangular chamber using one driver mounted at corner. Placement of driver at corner enables it to couple effectively to acoustic modes along all three axes. Use of single driver reduces cost, complexity and weight of levitation system below those of three driver system.

FInal Technical Repot of the Project: Design and Implementation of Low-Power 10Gb/s/channel Laser/Silicon Photonics Modulator Drivers with SEU Tolerance for HL-LHC

Energy Technology Data Exchange (ETDEWEB)

Gui, Ping [Southern Methodist Univ., Dallas, TX (United States)

2017-08-09

During the funding period of this award from May 1, 2014 through March 30, 2016, we have accomplished the design, implementation and measurement results of two laser driver chips: LpGBLD10+ which is a low-power single-channel 10Gb/s laser driver IC, and LDQ10P, which is a 4x10Gb/s driver array chip for High Energy Physics (HEP) applications. With new circuit techniques, the driver consumes a record-low power consumption, 31 mW @10Gb/s/channel and occupies a small area of 400 µm × 1750 µm for the single-channel driver IC and 1900umx1700um for the LDQ10P chip. These characteristics allow for both the LpGBLD10+ ICs and LDQ10P suitable candidate for the Versatile Link PLUS (VL+) project, offering flexibility in configuring multiple Transmitters and receivers.

Assessing the relationship between the Driver Behavior Questionnaire and the Driver Skill Inventory: Revealing sub-groups of drivers

DEFF Research Database (Denmark)

Martinussen, Laila Marianne; Møller, Mette; Prato, Carlo Giacomo

2014-01-01

The Driver Behavior Questionnaire and the Driver Skill Inventory are two of the most frequently used measures of self-reported driving style and driving skill. The motivation behind the present study was to identify sub-groups of drivers that potentially act dangerously in traffic (as measured...... self-reported driving skills and whether the reported skill level was reflected in the reported aberrant driving behaviors. 3908 drivers aged 18–84 participated in the survey. K-means cluster analysis revealed four distinct sub-groups that differed in driving skills and frequency of aberrant driving...... by frequency of aberrant driving behaviors and level of driving skills), as well as to test whether the sub-groups differ in characteristics such as age, gender, annual mileage and accident involvement. Furthermore, the joint analysis of the two instruments was used to test drivers’ assessment of their own...

Older drivers : a review.

NARCIS (Netherlands)

Hakamies-Blomqvist, L. Sirén, A. & Davidse, R.J.

2004-01-01

The proportion of senior citizens (aged 65+) will grow from about 15 per cent in the year 2000 to about 30 per cent in the year 2050. The share of older drivers in the driver population will grow even faster because of increasing licensing rates among the ageing population. Older drivers do not have

Integrated NEMS and optoelectronics for sensor applications.

Energy Technology Data Exchange (ETDEWEB)

Czaplewski, David A.; Serkland, Darwin Keith; Olsson, Roy H., III; Bogart, Gregory R. (Symphony Acoustics, Rio Rancho, NM); Krishnamoorthy, Uma; Warren, Mial E.; Carr, Dustin Wade (Symphony Acoustics, Rio Rancho, NM); Okandan, Murat; Peterson, Kenneth Allen

2008-01-01

This work utilized advanced engineering in several fields to find solutions to the challenges presented by the integration of MEMS/NEMS with optoelectronics to realize a compact sensor system, comprised of a microfabricated sensor, VCSEL, and photodiode. By utilizing microfabrication techniques in the realization of the MEMS/NEMS component, the VCSEL and the photodiode, the system would be small in size and require less power than a macro-sized component. The work focused on two technologies, accelerometers and microphones, leveraged from other LDRD programs. The first technology was the nano-g accelerometer using a nanophotonic motion detection system (67023). This accelerometer had measured sensitivity of approximately 10 nano-g. The Integrated NEMS and optoelectronics LDRD supported the nano-g accelerometer LDRD by providing advanced designs for the accelerometers, packaging, and a detection scheme to encapsulate the accelerometer, furthering the testing capabilities beyond bench-top tests. A fully packaged and tested die was never realized, but significant packaging issues were addressed and many resolved. The second technology supported by this work was the ultrasensitive directional microphone arrays for military operations in urban terrain and future combat systems (93518). This application utilized a diffraction-based sensing technique with different optical component placement and a different detection scheme from the nano-g accelerometer. The Integrated NEMS LDRD supported the microphone array LDRD by providing custom designs, VCSELs, and measurement techniques to accelerometers that were fabricated from the same operational principles as the microphones, but contain proof masses for acceleration transduction. These devices were packaged at the end of the work.

Cognitive characteristics of older Japanese drivers.

Science.gov (United States)

Susilowati, Indri H; Yasukouchi, Akira

2012-02-29

Some causes of accidents among older drivers are: not paying attention to traffic signals; missing stop lines; and having to deal with and misjudging emergency situations. These causes of accidents reveal problems with attention and cognition. Such incidents are also related to driver perception and stress-coping mechanisms. It is important to examine the relation of stress reactions to attention and cognition as a factor influencing the causes of accidents commonly involving older drivers. Subjects were 10 young drivers (23.3 ± 3.33 years) and 25 older drivers divided into two groups (older1 [60 to 65 years] and older2 [> 65 years]). This study revealed the correlation within driver stress inventory and driver coping questionnaires parameters was observed only in older drivers. They also needed a longer response time for Trail Making Test A and B. The factors affected the attention and cognition of older drivers by age but not driving experience itself, and coping parameters such as emotion focus, reappraisal, and avoidance were not included as stress inventory parameters. Being prone to fatigue was less for younger drivers than older drivers. Because they have shorter distances, shorter drive times, and no need for expressways, older drivers also had a significantly lower risk of thrill-seeking behaviour and more patience. The intervention addressing their attention skills, aggressive feelings, and emotion focus should be considered. The technological improvements in cars will make older drivers feel safer and make driving easier which might lower the attention paid to the road, and regular driving training might be needed to assess and enhance their safety.

Primary experimental results of wire-array Z-pinches on PTS

Energy Technology Data Exchange (ETDEWEB)

Huang, X. B., E-mail: caephxb2003@aliyun.com; Zhou, S. T., E-mail: caephxb2003@aliyun.com; Ren, X. D., E-mail: caephxb2003@aliyun.com; Dan, J. K., E-mail: caephxb2003@aliyun.com; Wang, K. L., E-mail: caephxb2003@aliyun.com; Zhang, S. Q., E-mail: caephxb2003@aliyun.com; Li, J., E-mail: caephxb2003@aliyun.com; Xu, Q., E-mail: caephxb2003@aliyun.com; Cai, H. C., E-mail: caephxb2003@aliyun.com; Duan, S. C., E-mail: caephxb2003@aliyun.com; Ouyang, K., E-mail: caephxb2003@aliyun.com; Chen, G. H., E-mail: caephxb2003@aliyun.com; Ji, C., E-mail: caephxb2003@aliyun.com; Wang, M., E-mail: caephxb2003@aliyun.com; Feng, S. P., E-mail: caephxb2003@aliyun.com; Yang, L. B., E-mail: caephxb2003@aliyun.com; Xie, W. P., E-mail: caephxb2003@aliyun.com; Deng, J. J., E-mail: caephxb2003@aliyun.com [Key Lab of Pulsed Power, Institute of Fluid Physics, CAEP, P.O. Box 919-108, Mianyang, Sichuan 621999 (China)

2014-12-15

The Primary Test Stand (PTS) developed at the China Academy of Engineering Physics is a multiterawatt pulsed power driver, which can deliver a ∼10 MA, 70 ns rise-time (10%-90%) current to a short circuit load and has important applications in Z-pinch driven inertial confinement fusion and high energy density physics. In this paper, primary results of tungsten wire-array Z-pinch experiments on PTS are presented. The load geometries investigated include 15-mm-tall cylindrical single and nested arrays with diameter ranging from 14.4-26.4 mm, and consisting of 132∼276 tungsten wires with 5∼10 μm in diameter. Multiple diagnostics were fielded to determine the characteristics of x-ray radiations and to obtain self-emitting images of imploding plasmas. X-ray power up to 80 TW with ∼3 ns FWMH is achieved by using nested wire arrays. The total x-ray energy exceeds 500 kJ and the peak radiation temperature is about 150 eV. Typical velocity of imploding plasmas goes around 3∼5×10{sup 7} cm/s and the radial convergence ratio is between 10 and 20.

Parallel interconnect for a novel system approach to short distance high information transfer data links

Science.gov (United States)

Raskin, Glenn; Lebby, Michael S.; Carney, F.; Kazakia, M.; Schwartz, Daniel B.; Gaw, Craig A.

1997-04-01

The OPTOBUSTM family of products provides for high performance parallel interconnection utilizing optical links in a 10-bit wide bi-directional configuration. The link is architected to be 'transparent' in that it is totally asynchronous and dc coupled so that it can be treated as a perfect cable with extremely low skew and no losses. An optical link consists of two identical transceiver modules and a pair of connectorized 62.5 micrometer multi mode fiber ribbon cables. The OPTOBUSTM I link provides bi- directional functionality at 4 Gbps (400 Mbps per channel), while the OPTOBUSTM II link will offer the same capability at 8 Gbps (800 Mbps per channel). The transparent structure of the OPTOBUSTM links allow for an arbitrary data stream regardless of its structure. Both the OPTOBUSTM I and OPTOBUSTM II transceiver modules are packaged as partially populated 14 by 14 pin grid arrays (PGA) with optical receptacles on one side of the module. The modules themselves are composed of several elements; including passives, integrated circuits optoelectronic devices and optical interface units (OIUs) (which consist of polymer waveguides and a specially designed lead frame). The initial offering of the modules electrical interface utilizes differential CML. The CML line driver sinks 5 mA of current into one of two pins. When terminated with 50 ohm pull-up resistors tied to a voltage between VCC and VCC-2, the result is a differential swing of plus or minus 250 mV, capable of driving standard PECL I/Os. Future offerings of the OPTOBUSTM links will incorporate LVDS and PECL interfaces as well as CML. The integrated circuits are silicon based. For OPTOBUSTM I links, a 1.5 micrometer drawn emitter NPN bipolar process is used for the receiver and an enhanced 0.8 micrometer CMOS process for the laser driver. For OPTOBUSTM II links, a 0.8 micrometer drawn emitter NPN bipolar process is used for the receiver and the driver IC utilizes 0.8 micrometer BiCMOS technology. The OPTOBUSTM

Cognitive characteristics of older Japanese drivers

Directory of Open Access Journals (Sweden)

Susilowati Indri H

2012-02-01

Full Text Available Abstract Background Some causes of accidents among older drivers are: not paying attention to traffic signals; missing stop lines; and having to deal with and misjudging emergency situations. These causes of accidents reveal problems with attention and cognition. Such incidents are also related to driver perception and stress-coping mechanisms. It is important to examine the relation of stress reactions to attention and cognition as a factor influencing the causes of accidents commonly involving older drivers. Finding Subjects were 10 young drivers (23.3 ± 3.33 years and 25 older drivers divided into two groups (older1 [60 to 65 years] and older2 [> 65 years]. This study revealed the correlation within driver stress inventory and driver coping questionnaires parameters was observed only in older drivers. They also needed a longer response time for Trail Making Test A and B. The factors affected the attention and cognition of older drivers by age but not driving experience itself, and coping parameters such as emotion focus, reappraisal, and avoidance were not included as stress inventory parameters. Being prone to fatigue was less for younger drivers than older drivers. Because they have shorter distances, shorter drive times, and no need for expressways, older drivers also had a significantly lower risk of thrill-seeking behaviour and more patience. Conclusion The intervention addressing their attention skills, aggressive feelings, and emotion focus should be considered. The technological improvements in cars will make older drivers feel safer and make driving easier which might lower the attention paid to the road, and regular driving training might be needed to assess and enhance their safety.

Assisting Driver Sovereignty : A Fail-Safe Design Approach to Driver Distraction

NARCIS (Netherlands)

Van Gijssel, A.

2013-01-01

This thesis investigates the potential of a fail-safe approach to driver distraction through novel interface concepts for integrated Advanced Driver Assistance Systems (ADAS). Traffic accidents are a negative side effect of the universal and economical desire for mobility. The year 2009 saw the

Novice drivers' individual trajectories of driver behavior over the first three years of driving.

Science.gov (United States)

Roman, Gabriela D; Poulter, Damian; Barker, Edward; McKenna, Frank P; Rowe, Richard

2015-09-01

Identifying the changes in driving behavior that underlie the decrease in crash risk over the first few months of driving is key to efforts to reduce injury and fatality risk in novice drivers. This study represented a secondary data analysis of 1148 drivers who participated in the UK Cohort II study. The Driver Behavior Questionnaire was completed at 6 months and 1, 2 and 3 years after licensure. Linear latent growth models indicated significant increases across development in all four dimensions of aberrant driving behavior under scrutiny: aggressive violations, ordinary violations, errors and slips. Unconditional and conditional latent growth class analyses showed that the observed heterogeneity in individual trajectories was explained by the presence of multiple homogeneous groups of drivers, each exhibiting specific trajectories of aberrant driver behavior. Initial levels of aberrant driver behavior were important in identifying sub-groups of drivers. All classes showed positive slopes; there was no evidence of a group of drivers whose aberrant behavior decreased over time that might explain the decrease in crash involvement observed over this period. Male gender and younger age predicted membership of trajectories with higher levels of aberrant behavior. These findings highlight the importance of early intervention for improving road safety. We discuss the implications of our findings for understanding the behavioral underpinnings of the decrease in crash involvement observed in the early months of driving. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Use of microsecond current prepulse for dramatic improvements of wire array Z-pinch implosion

International Nuclear Information System (INIS)

Calamy, H.; Lassalle, F.; Loyen, A.; Zucchini, F.; Chittenden, J. P.; Hamann, F.; Maury, P.; Georges, A.; Bedoch, J. P.; Morell, A.

2008-01-01

The Sphinx machine [F. Lassalle et al., 'Status on the SPHINX machine based on the 1microsecond LTD technology'] based on microsecond linear transformer driver (LTD) technology is used to implode an aluminium wire array with an outer diameter up to 140 mm and maximum current from 3.5 to 5 MA. 700 to 800 ns implosion Z-pinch experiments are performed on this driver essentially with aluminium. Best results obtained before the improvement described in this paper were 1-3 TW radial total power, 100-300 kJ total yield, and 20-30 kJ energy above 1 keV. An auxiliary generator was added to the Sphinx machine in order to allow a multi microsecond current to be injected through the wire array load before the start of the main current. Amplitude and duration of this current prepulse are adjustable, with maxima ∼10 kA and 50 μs. This prepulse dramatically changes the ablation phase leading to an improvement of the axial homogeneity of both the implosion and the final radiating column. Total power was multiplied by a factor of 6, total yield by a factor of 2.5 with a reproducible behavior. This paper presents experimental results, magnetohydrodynamic simulations, and analysis of the effect of such a long current prepulse

The performance of an LSI-11/23 with a SKYMNK-Q array processor as a high speed front end processor

International Nuclear Information System (INIS)

Clark, D.L.

1983-01-01

The NSRL has recently installed a VAX-11/750 based data acquisition system which is networked to two LSI-11/23 satellite processors. Each of the LSI's are connected to CAMAC branch drivers. The LSI's have small array processors installed for use in preprocessing data. The objective is to provide an easy to use high speed processor that will relieve the VAX of some of the real-time data analysis tasks. The basic operation of the array processor and some of the results of performance tests are described

"The little squealer" or "the virtual guardian angel"? Young drivers' and their parents' perspective on using a driver monitoring technology and its implications for parent-young driver communication.

Science.gov (United States)

Guttman, Nurit; Gesser-Edelsburg, Anat

2011-02-01

In-vehicle driving monitoring technologies have the potential to enable young drivers to learn from self-assessment. However, their use is largely dependent on parental involvement. A total of 79 interviews were conducted with young drivers and parents regarding this technology and its use. Most had the experience of having an in-vehicle data recorder installed in the vehicle driven by the young drivers. Parents and the young drivers expressed both appreciation as well as reservations about its potential as a means to enhance the driving safety of young drivers. A surprising finding was that some parents did not check the feedback and said they relied on the young driver to do so. Main concerns related to privacy, parent-young driver relationship, self-esteem and confidence, constructive use of the feedback data, and the limitations of the documentation that can be done by the technology. Providing parents and young drivers with a support system and tools to discuss and utilize the feedback are underscored. Challenges include addressing the invasion of young drivers' privacy and gender differences, and using the monitoring-capacity of the technology to enhance safe driving practices. Implications for programs to enhance communication and a dialogical approach between parents and young drivers are discussed. Copyright © 2010 Elsevier Ltd. All rights reserved.

Scalable Earth-observation Analytics for Geoscientists: Spacetime Extensions to the Array Database SciDB

Science.gov (United States)

Appel, Marius; Lahn, Florian; Pebesma, Edzer; Buytaert, Wouter; Moulds, Simon

2016-04-01

Today's amount of freely available data requires scientists to spend large parts of their work on data management. This is especially true in environmental sciences when working with large remote sensing datasets, such as obtained from earth-observation satellites like the Sentinel fleet. Many frameworks like SpatialHadoop or Apache Spark address the scalability but target programmers rather than data analysts, and are not dedicated to imagery or array data. In this work, we use the open-source data management and analytics system SciDB to bring large earth-observation datasets closer to analysts. Its underlying data representation as multidimensional arrays fits naturally to earth-observation datasets, distributes storage and computational load over multiple instances by multidimensional chunking, and also enables efficient time-series based analyses, which is usually difficult using file- or tile-based approaches. Existing interfaces to R and Python furthermore allow for scalable analytics with relatively little learning effort. However, interfacing SciDB and file-based earth-observation datasets that come as tiled temporal snapshots requires a lot of manual bookkeeping during ingestion, and SciDB natively only supports loading data from CSV-like and custom binary formatted files, which currently limits its practical use in earth-observation analytics. To make it easier to work with large multi-temporal datasets in SciDB, we developed software tools that enrich SciDB with earth observation metadata and allow working with commonly used file formats: (i) the SciDB extension library scidb4geo simplifies working with spatiotemporal arrays by adding relevant metadata to the database and (ii) the Geospatial Data Abstraction Library (GDAL) driver implementation scidb4gdal allows to ingest and export remote sensing imagery from and to a large number of file formats. Using added metadata on temporal resolution and coverage, the GDAL driver supports time-based ingestion of

Young novice drivers.

NARCIS (Netherlands)

2013-01-01

In The Netherlands, young novice drivers (18-24 years of age) show a crash rate that is five times higher than that of experienced drivers (30-59 years of age). The rate of young males is even seven times as high. The main reasons are lack of driving experience and hazardous behaviour typical of

Determination of Amphetamine, Amfepramone and Fenproporex in Urine Samples by HPLC-DAD: Application to a Population of Brazilian Truck Drivers

OpenAIRE

Takitane, Juliana; Almeida, Rafael M.; Oliveira, Tiago F.; Prado, Natanael V.; Muñoz, Daniel R.; Leyton, Vilma; Yonamine, Mauricio

2016-01-01

Commercially available immunoassay tests are designed to detect the presence of amphetamine/methamphetamine or methylenodioxyamphetamines. However, it is known that Brazilian truck drivers also report the use of other illicit amphetamines, such as amfepramone and fenproporex. Thus, a method was developed and validated in order to quantify amphetamine-type stimulants (amphetamine, fenproporex and amfepramone) in urine by high performance liquid chromatography with diode array detection (HPLC-D...

Driver behavior analysis for right-turn drivers at signalized intersections using SHRP 2 naturalistic driving study data.

Science.gov (United States)

Wu, Jianqing; Xu, Hao

2017-12-01

Understanding driver behavior is important for traffic safety and operation, especially at intersections where different traffic movements conflict. While most driver-behavior studies are based on simulation, this paper documents the analysis of driver-behavior at signalized intersections with the SHRP 2 Naturalistic Driving Study (NDS) data. This study analyzes the different influencing factors on the operation (speed control) and observation of right-turn drivers. A total of 300 NDS trips at six signalized intersections were used, including the NDS time-series sensor data, the forward videos and driver face videos. Different factors of drivers, vehicles, roads and environments were studied for their influence on driver behavior. An influencing index function was developed and the index was calculated for each influencing factor to quantitatively describe its influencing level. The influencing index was applied to prioritize the factors, which facilitates development and selection of safety countermeasures to improve intersection safety. Drivers' speed control was analyzed under different conditions with consideration of the prioritized influencing factors. Vehicle type, traffic signal status, conflicting traffic, conflicting pedestrian and driver age group were identified as the five major influencing factors on driver observation. This research revealed that drivers have high acceleration and low observation frequency under Right-Turn-On-Red (RTOR), which constituted potential danger for other roadway users, especially for pedestrians. As speed has a direct influence on crash rates and severities, the revealed speed patterns of the different situations also benefit selection of safety countermeasures at signalized intersections. Published by Elsevier Ltd.

Experimental Research in Boost Driver with EDLCs

Science.gov (United States)

Matsumoto, Hirokazu

The supply used in servo systems tends to have a high voltage in order to reduce loss and improve the response of motor drives. We propose a new boost motor driver that comprises EDLCs. The proposed driver has a simple structure, wherein the EDLCs are connected in series to the supply, and comprises a charge circuit to charge the EDLCs. The proposed driver has three advantages over conventional boost drivers. The first advantage is that the driver can easily attain the stable boost voltage. The second advantage is that the driver can reduce input power peaks. In a servo system, the input power peaks become greater than the rated power in order to accelerate the motor rapidly. This implies that the equipments that supply power to servo systems must have sufficient power capacity to satisfy the power peaks. The proposed driver can suppress the increase of the power capacity of supply facilities. The third advantage is that the driver can store almost all of the regenerative energy. Conventional drivers have a braking resistor to suppress the increase in the DC link voltage. This causes a considerable reduction in the efficiency. The proposed driver is more efficient than conventional drivers. In this study, the experimental results confirmed the effectiveness of the proposed driver and showed that the drive performance of the proposed driver is the same as that of a conventional driver. Furthermore, it was confirmed that the results of the simulation of a model of the EDLC module, whose capacitance is dependent on the frequency, correspond well with the experimental results.

Driver competence performance indicators using OTMR

Energy Technology Data Exchange (ETDEWEB)

Hassan EL Rashidy, R.A.

2016-07-01

The current practice for assessing driver competence performance is in-cab riding by driver managers. However, this paper investigates whether real-world driving data extracted from on-train monitoring recorders data (OTMR) can be used to assess the driver performance. A number of indicators were used to evaluate the drivers’ performance. These include: their use of the emergency bypass switch, the driver's reminder appliance as well as the driver’s reaction time. A study case illustrated the applicability of OTMR data to estimate the proposed indicators, which suggests that the indicators can be useful in the driver management system in addition to the current indicators. Furthermore, the proposed indicators could be used to tailor the driver training schemes up to their individual needs and evaluate their effectiveness. They could even be used for improving driver competence performance and reducing crash involvement by revealing potentially detrimental driving performance. (Author)

Large-Eddy Simulation on Plume Dispersion within Regular Arrays of Cubic Buildings

Science.gov (United States)

Nakayama, H.; Jurcakova, K.; Nagai, H.

2010-09-01

There is a potential problem that hazardous and flammable materials are accidentally or intentionally released into the atmosphere, either within or close to populated urban areas. For the assessment of human health hazard from toxic substances, the existence of high concentration peaks in a plume should be considered. For the safety analysis of flammable gas, certain critical threshold levels should be evaluated. Therefore, in such a situation, not only average levels but also instantaneous magnitudes of concentration should be accurately predicted. However, plume dispersion is an extremely complicated process strongly influenced by the existence of buildings. In complex turbulent flows, such as impinging, separated and circulation flows around buildings, plume behaviors can be no longer accurately predicted using empirical Gaussian-type plume model. Therefore, we perform Large-Eddy Simulations (LES) on turbulent flows and plume dispersions within and over regular arrays of cubic buildings with various roughness densities and investigate the influence of the building arrangement pattern on the characteristics of mean and fluctuation concentrations. The basic equations for the LES model are composed of the spatially filtered continuity equation, Navier-Stokes equation and transport equation of concentration. The standard Smagorinsky model (Smagorinsky, 1963) that has enough potential for environment flows is used and its constant is set to 0.12 for estimating the eddy viscosity. The turbulent Schmidt number is 0.5. In our LES model, two computational regions are set up. One is a driver region for generation of inflow turbulence and the other is a main region for LES of plume dispersion within a regular array of cubic buildings. First, inflow turbulence is generated by using Kataoka's method (2002) in the driver region and then, its data are imposed at the inlet of the main computational region at each time step. In this study, the cubic building arrays with λf=0

Online driver's license renewal.

Science.gov (United States)

2015-09-01

The Kentucky Department of Vehicle Regulation is exploring the possibility of developing and implementing online : drivers license renewal. The objective of this project was to: 1) evaluate online drivers license and REAL ID renewal : programs ...

Array capabilities and future arrays

International Nuclear Information System (INIS)

Radford, D.

1993-01-01

Early results from the new third-generation instruments GAMMASPHERE and EUROGAM are confirming the expectation that such arrays will have a revolutionary effect on the field of high-spin nuclear structure. When completed, GAMMASHPERE will have a resolving power am order of magnitude greater that of the best second-generation arrays. When combined with other instruments such as particle-detector arrays and fragment mass analysers, the capabilites of the arrays for the study of more exotic nuclei will be further enhanced. In order to better understand the limitations of these instruments, and to design improved future detector systems, it is important to have some intelligible and reliable calculation for the relative resolving power of different instrument designs. The derivation of such a figure of merit will be briefly presented, and the relative sensitivities of arrays currently proposed or under construction presented. The design of TRIGAM, a new third-generation array proposed for Chalk River, will also be discussed. It is instructive to consider how far arrays of Compton-suppressed Ge detectors could be taken. For example, it will be shown that an idealised open-quote perfectclose quotes third-generation array of 1000 detectors has a sensitivity an order of magnitude higher again than that of GAMMASPHERE. Less conventional options for new arrays will also be explored

Exploratory multinomial logit model-based driver injury severity analyses for teenage and adult drivers in intersection-related crashes.

Science.gov (United States)

Wu, Qiong; Zhang, Guohui; Ci, Yusheng; Wu, Lina; Tarefder, Rafiqul A; Alcántara, Adélamar Dely

2016-05-18

Teenage drivers are more likely to be involved in severely incapacitating and fatal crashes compared to adult drivers. Moreover, because two thirds of urban vehicle miles traveled are on signal-controlled roadways, significant research efforts are needed to investigate intersection-related teenage driver injury severities and their contributing factors in terms of driver behavior, vehicle-infrastructure interactions, environmental characteristics, roadway geometric features, and traffic compositions. Therefore, this study aims to explore the characteristic differences between teenage and adult drivers in intersection-related crashes, identify the significant contributing attributes, and analyze their impacts on driver injury severities. Using crash data collected in New Mexico from 2010 to 2011, 2 multinomial logit regression models were developed to analyze injury severities for teenage and adult drivers, respectively. Elasticity analyses and transferability tests were conducted to better understand the quantitative impacts of these factors and the teenage driver injury severity model's generality. The results showed that although many of the same contributing factors were found to be significant in the both teenage and adult driver models, certain different attributes must be distinguished to specifically develop effective safety solutions for the 2 driver groups. The research findings are helpful to better understand teenage crash uniqueness and develop cost-effective solutions to reduce intersection-related teenage injury severities and facilitate driver injury mitigation research.

The CMS Tracker Readout Front End Driver

CERN Document Server

Foudas, C.; Ballard, D.; Church, I.; Corrin, E.; Coughlan, J.A.; Day, C.P.; Freeman, E.J.; Fulcher, J.; Gannon, W.J.F.; Hall, G.; Halsall, R.N.J.; Iles, G.; Jones, J.; Leaver, J.; Noy, M.; Pearson, M.; Raymond, M.; Reid, I.; Rogers, G.; Salisbury, J.; Taghavi, S.; Tomalin, I.R.; Zorba, O.

2004-01-01

The Front End Driver, FED, is a 9U 400mm VME64x card designed for reading out the Compact Muon Solenoid, CMS, silicon tracker signals transmitted by the APV25 analogue pipeline Application Specific Integrated Circuits. The FED receives the signals via 96 optical fibers at a total input rate of 3.4 GB/sec. The signals are digitized and processed by applying algorithms for pedestal and common mode noise subtraction. Algorithms that search for clusters of hits are used to further reduce the input rate. Only the cluster data along with trigger information of the event are transmitted to the CMS data acquisition system using the S-LINK64 protocol at a maximum rate of 400 MB/sec. All data processing algorithms on the FED are executed in large on-board Field Programmable Gate Arrays. Results on the design, performance, testing and quality control of the FED are presented and discussed.

Evaluating Older Drivers' Skills

Science.gov (United States)

2013-05-01

Research has demonstrated that older drivers pose a higher risk of involvement in fatal crashes at intersections than : younger drivers. Age-triggered restrictions are problematic as research shows that the majority of older people : have unimpaired ...

A High-Performance Deformable Mirror with Integrated Driver ASIC for Space Based Active Optics

Science.gov (United States)

Shelton, Chris

Direct imaging of exoplanets is key to fully understanding these systems through spectroscopy and astrometry. The primary impediment to direct imaging of exoplanets is the extremely high brightness ratio between the planet and its parent star. Direct imaging requires a technique for contrast suppression, which include coronagraphs, and nulling interferometers. Deformable mirrors (DMs) are essential to both of these techniques. With space missions in mind, Microscale is developing a novel DM with direct integration of DM and its electronic control functions in a single small envelope. The Application Specific Integrated Circuit (ASIC) is key to the shrinking of the electronic control functions to a size compatible with direct integration with the DM. Through a NASA SBIR project, Microscale, with JPL oversight, has successfully demonstrated a unique deformable mirror (DM) driver ASIC prototype based on an ultra-low power switch architecture. Microscale calls this the Switch-Mode ASIC, or SM-ASIC, and has characterized it for a key set of performance parameters, and has tested its operation with a variety of actuator loads, such as piezo stack and unimorph, and over a wide temperature range. These tests show the SM-ASIC's capability of supporting active optics in correcting aberrations of a telescope in space. Microscale has also developed DMs to go with the SM-ASIC driver. The latest DM version produced uses small piezo stack elements in an 8x8 array, bonded to a novel silicon facesheet structure fabricated monolithically into a polished mirror on one side and mechanical linkage posts that connect to the piezoelectric stack actuators on the other. In this Supporting Technology proposal we propose to further develop the ASIC-DM and have assembled a very capable team to do so. It will be led by JPL, which has considerable expertise with DMs used in Adaptive Optics systems, with high-contrast imaging systems for exoplanet missions, and with designing DM driver

Anthropogenic Drivers of Ecosystem Change: an Overview

Directory of Open Access Journals (Sweden)

Gerald C. Nelson

2006-12-01

Full Text Available This paper provides an overview of what the Millennium Ecosystem Assessment (MA calls "indirect and direct drivers" of change in ecosystem services at a global level. The MA definition of a driver is any natural or human-induced factor that directly or indirectly causes a change in an ecosystem. A direct driver unequivocally influences ecosystem processes. An indirect driver operates more diffusely by altering one or more direct drivers. Global driving forces are categorized as demographic, economic, sociopolitical, cultural and religious, scientific and technological, and physical and biological. Drivers in all categories other than physical and biological are considered indirect. Important direct drivers include changes in climate, plant nutrient use, land conversion, and diseases and invasive species. This paper does not discuss natural drivers such as climate variability, extreme weather events, or volcanic eruptions.

Drivers' reactions to sudden lead car braking under varying workload conditions; towards a driver support system.

NARCIS (Netherlands)

Schaap, Nina; van der Horst, A.R.A.; van Arem, Bart; Brookhuis, K.A.

2008-01-01

At urban intersections drivers handle multiple tasks simultaneously, making urban driving a complex task. An advanced driver assistance system may support drivers in this specific driving task, but the design details of such a system need to be determined before they can be fully deployed. A driving

General oilfield driver improvement

International Nuclear Information System (INIS)

Johnson, G.

1997-01-01

The general oilfield driver improvement (GODI) course was discussed. The course is offered to truckers in the oil and gas industry to help reduce accidents and injuries. Oilfield trucking is one of the most accident and injury prone sectors in the Alberta economy. This paper presented Heck's Trucking company's experience in sending its employees on the course. Drivers were taught (1) the National safety code requirements, (2) Commercial Vehicle Safety Alliance requirements, (3) occupational health and safety concerns, (4) vehicle dimension and GVW restrictions, (5) hours of service regulations, (6) log book and pre-trip inspection requirements, (7) workplace hazardous material information, and (8) transportation of dangerous goods. Overall, the course was judged to provide excellent training before sending drivers into the field. The employee, the customer, and the company, all stand to benefit from having rigorous and uniform standards for all drivers in the oil and gas industry

VD-411 branch driver

International Nuclear Information System (INIS)

Gorbunov, N.V.; Karev, A.G.; Mal'tsev, Eh.I.; Morozov, B.A.

1985-01-01

The VD-411 branch driver for CAMAC moduli control by the SM-4 computer is described. The driver realizes data exchange with moduli disposed in 28 crates grouped in 4 branches. Data exchange can be carried out either in the program regime or in the regime of direct access to the memory. Fulfilment of 11 block regimes and one program regime is provided for. A possibility of individual programming of exchange methods in block regimes is left for users for organisation of quicker and most flexible data removal from the CAMAC moduli. In the regime of direct access the driver provides data transmission at the size up to 64 Kwords placing it in the computer memory of 2 M byte. High rate of data transmission and the developed system of interruptions ensure efficient utilization of the VD-411 branch driver at data removal from facilities in high energy physics experiments

Integrated Micro-Optical Fluorescence Detection System for Microfluidic Electrochromatography

International Nuclear Information System (INIS)

ALLERMAN, ANDREW A.; ARNOLD, DON W.; ASBILL, RANDOLPH E.; BAILEY, CHRISTOPHER G.; CARTER, TONY RAY; KEMME, SHANALYN A.; MATZKE, CAROLYN M.; SAMORA, SALLY; SWEATT, WILLIAM C.; WARREN, MIAL E.; WENDT, JOEL R.

1999-01-01

The authors describe the design and microfabrication of an extremely compact optical system as a key element in an integrated capillary-channel electrochromatograph with laser induced fluorescence detection. The optical design uses substrate-mode propagation within the fused silica substrate. The optical system includes a vertical cavity surface-emitting laser (VCSEL) array, two high performance microlenses and a commercial photodetector. The microlenses are multilevel diffractive optics patterned by electron beam lithography and etched by reactive ion etching in fused silica. Two generations of optical subsystems are described. The first generation design is integrated directly onto the capillary channel-containing substrate with a 6 mm separation between the VCSEL and photodetector. The second generation design separates the optical system onto its own module and the source to detector length is further compressed to 3.5 mm. The systems are designed for indirect fluorescence detection using infrared dyes. The first generation design has been tested with a 750 nm VCSEL exciting a 10(sup -4) M solution of CY-7 dye. The observed signal-to-noise ratio of better than 100:1 demonstrates that the background signal from scattered pump light is low despite the compact size of the optical system and meets the system sensitivity requirements

The low-frequency array (LOFAR): opening a new window on the universe

Science.gov (United States)

Kassim, N. E.; Lazio, T. J. W.; Ray, P. S.; Crane, P. C.; Hicks, B. C.; Stewart, K. P.; Cohen, A. S.; Lane, W. M.

2004-12-01

We present an overview of the low-frequency array (LOFAR) that will open a window on one of the last and most poorly explored regions of the electromagnetic spectrum. LOFAR will be a large (baselines up to 400 km), low-frequency (ν˜10-240MHz) aperture synthesis array with large collecting area ( ˜106m2 at 15MHz) and high resolution ( ˜1.5″ at 100 MHz), and will provide sub-mJy sensitivity across much of its operating range. LOFAR will be a powerful instrument for solar system and planetary science applications as reviewed by papers in this monogram. Key astrophysical science drivers include acceleration, turbulence, and propagation in the galactic interstellar medium, exploring the high red-shift universe and transient phenomena, as well as searching for the red-shifted signature of neutral hydrogen from the cosmologically important epoch of re-ionization.

Driver Distraction in Public Transport

OpenAIRE

YOUNG, K; SALMON, P; REGAN MICHAEL, M

2007-01-01

There is converging evidence that driver distraction is a contributing factor in car crashes, in Australia and overseas. Surprisingly, no known previous research has attempted to identify and assess the potentially distracting activities undertaken by the drivers of public passenger vehicles. This paper describes research undertaken on this issue. The research was partitioned into three phases: an analysis of the functions and tasks currently undertaken by public passenger vehicle drivers; th...

Criteria for driver impairment

NARCIS (Netherlands)

Brookhuis, K.A.; De Waard, D.; Fairclough, S.H

2003-01-01

Most traffic accidents can be attributed to driver impairment, e.g. inattention, fatigue, intoxication, etc. It is now technically feasible to monitor and diagnose driver behaviour with respect to impairment with the aid of a limited number of in-vehicle sensors. However, a valid framework for the

Development of diode-pumped solid-state laser HALNA for fusion reactor driver

International Nuclear Information System (INIS)

Kawashima, Toshiyuki; Kanabe, Tadashi; Matsumoto, Osamu

2005-01-01

The diode-pumped slab laser for inertial fusion energy driver has been demonstrated, which produces the 1053-nm output energy of 10 J at 10 Hz. The glass slab laser amplifier has been pumped by quasi-CW 290 kW AlGaAs laser-diode arrays at 803 nm. The optical system can compensate for thermal effects by use of zig-zag optical propagation, image-relayed telescope, and 45deg Faraday rotator. The output energy of 10.6 J at 1 Hz with the optical to optical conversion efficiency of 19.9% has been successfully obtained. Also the 10 Hz operation has been performed with a 5.1 J output energy. (author)

49 CFR 396.13 - Driver inspection.

Science.gov (United States)

2010-10-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION FEDERAL MOTOR CARRIER SAFETY REGULATIONS INSPECTION, REPAIR, AND MAINTENANCE § 396.13 Driver inspection. Before driving a motor vehicle, the driver shall: (a) Be satisfied that the motor vehicle is in safe operating condition; (b) Review the last driver vehicle inspection...

IFE Power Plant design principles. Drivers. Solid state laser drivers

International Nuclear Information System (INIS)

Nakai, S.; Andre, M.; Krupke, W.F.; Mak, A.A.; Soures, J.M.; Yamanaka, M.

1995-01-01

The present status of solid state laser drivers for an inertial confinement thermonuclear fusion power plant is discussed. In particular, the feasibility of laser diode pumped solid state laser drivers from both the technical and economic points of view is briefly reviewed. Conceptual design studies showed that they can, in principle, satisfy the design requirements. However, development of new solid state materials with long fluorescence lifetimes and good thermal characteristics is a key issue for laser diode pumped solid state lasers. With the advent of laser diode pumping many materials which were abandoned in the past can presently be reconsidered as viable candidates. It is also concluded that it is important to examine the technical requirements for solid state lasers in relation to target performance criteria. The progress of laser diode pumped lasers in industrial applications should also be closely watched to provide additional information on the economic feasibility of this type of driver. 15 refs, 9 figs, 2 tabs

Data and methods for studying commercial motor vehicle driver fatigue, highway safety and long-term driver health.

Science.gov (United States)

Stern, Hal S; Blower, Daniel; Cohen, Michael L; Czeisler, Charles A; Dinges, David F; Greenhouse, Joel B; Guo, Feng; Hanowski, Richard J; Hartenbaum, Natalie P; Krueger, Gerald P; Mallis, Melissa M; Pain, Richard F; Rizzo, Matthew; Sinha, Esha; Small, Dylan S; Stuart, Elizabeth A; Wegman, David H

2018-03-09

This article summarizes the recommendations on data and methodology issues for studying commercial motor vehicle driver fatigue of a National Academies of Sciences, Engineering, and Medicine study. A framework is provided that identifies the various factors affecting driver fatigue and relating driver fatigue to crash risk and long-term driver health. The relevant factors include characteristics of the driver, vehicle, carrier and environment. Limitations of existing data are considered and potential sources of additional data described. Statistical methods that can be used to improve understanding of the relevant relationships from observational data are also described. The recommendations for enhanced data collection and the use of modern statistical methods for causal inference have the potential to enhance our understanding of the relationship of fatigue to highway safety and to long-term driver health. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Drivers' reactions to sudden braking by lead car under varying workload conditions; towards a driver support system

NARCIS (Netherlands)

Schaap, T. W.; van der Horst, A. R. A.; van Arem, B.; Brookhuis, K. A.

2008-01-01

At urban intersections drivers handle multiple tasks simultaneously, making urban driving a complex task. An advanced driver assistance system may support drivers in this specific driving task, but the design details of such a system need to be determined before they can be fully deployed. A driving

Fusion of optimized indicators from Advanced Driver Assistance Systems (ADAS) for driver drowsiness detection.

Science.gov (United States)

Daza, Iván García; Bergasa, Luis Miguel; Bronte, Sebastián; Yebes, Jose Javier; Almazán, Javier; Arroyo, Roberto

2014-01-09

This paper presents a non-intrusive approach for monitoring driver drowsiness using the fusion of several optimized indicators based on driver physical and driving performance measures, obtained from ADAS (Advanced Driver Assistant Systems) in simulated conditions. The paper is focused on real-time drowsiness detection technology rather than on long-term sleep/awake regulation prediction technology. We have developed our own vision system in order to obtain robust and optimized driver indicators able to be used in simulators and future real environments. These indicators are principally based on driver physical and driving performance skills. The fusion of several indicators, proposed in the literature, is evaluated using a neural network and a stochastic optimization method to obtain the best combination. We propose a new method for ground-truth generation based on a supervised Karolinska Sleepiness Scale (KSS). An extensive evaluation of indicators, derived from trials over a third generation simulator with several test subjects during different driving sessions, was performed. The main conclusions about the performance of single indicators and the best combinations of them are included, as well as the future works derived from this study.

Fusion of Optimized Indicators from Advanced Driver Assistance Systems (ADAS for Driver Drowsiness Detection

Directory of Open Access Journals (Sweden)

Iván G. Daza

2014-01-01

Full Text Available This paper presents a non-intrusive approach for monitoring driver drowsiness using the fusion of several optimized indicators based on driver physical and driving performance measures, obtained from ADAS (Advanced Driver Assistant Systems in simulated conditions. The paper is focused on real-time drowsiness detection technology rather than on long-term sleep/awake regulation prediction technology. We have developed our own vision system in order to obtain robust and optimized driver indicators able to be used in simulators and future real environments. These indicators are principally based on driver physical and driving performance skills. The fusion of several indicators, proposed in the literature, is evaluated using a neural network and a stochastic optimization method to obtain the best combination. We propose a new method for ground-truth generation based on a supervised Karolinska Sleepiness Scale (KSS. An extensive evaluation of indicators, derived from trials over a third generation simulator with several test subjects during different driving sessions, was performed. The main conclusions about the performance of single indicators and the best combinations of them are included, as well as the future works derived from this study.

Microprocessor-based stepping motor driver

International Nuclear Information System (INIS)

Halbig, J.K.; Klosterbuer, S.F.

1979-09-01

The Pion Generation for Medical Irradiations (PIGMI) program at the Los Alamos Scientific Laboratory requires a versatile stepping motor driver to do beam diagnostic measurements. A driver controlled by a microprocessor that can move eight stepping motors simultaneously was designed. The driver can monitor and respond to clockwise- and counterclockwise-limit switches, and it can monitor a 0- to 10-V dc position signal. The software controls start and stop ramping and maximum stepping rates. 2 figures, 1 table

Advanced driver assistance systems for teen drivers: Teen and parent impressions, perceived need, and intervention preferences.

Science.gov (United States)

Weiss, Eve; Fisher Thiel, Megan; Sultana, Nahida; Hannan, Chloe; Seacrist, Thomas

2018-02-28

From the advent of airbags to electronic stability control, technological advances introduced into automobile design have significantly reduced injury and death from motor vehicle crashes. These advances are especially pertinent among teen drivers, a population whose leading cause of death is motor vehicle crashes. Recently developed advanced driver assistance systems (ADAS) have the potential to compensate for skill deficits and reduce overall crash risk. Yet, ADAS is only effective if drivers are willing to use it. Limited research has been conducted on the suitability of ADAS for teen drivers. The goal of this study is to identify teen drivers' perceived need for ADAS, receptiveness to in-vehicle technology, and intervention preferences. The long-term goal is to understand public perceptions and barriers to ADAS use and to help determine how these systems must evolve to meet the needs of the riskiest driving populations. Three focus groups (N = 24) were conducted with licensed teen drivers aged 16-19 years and 2 focus groups with parents of teen drivers (N = 12). Discussion topics included views on how ADAS might influence driving skills and behaviors; trust in technology; and data privacy. Discussions were transcribed; the team used conventional content analysis and open coding methods to identify 12 coding domains and code transcripts with NVivo 10. Interrater reliability testing showed moderate to high kappa scores. Overall, participants recognized potential benefits of ADAS, including improved safety and crash reduction. Teens suggested that ADAS is still developing and therefore has potential to malfunction. Many teens reported a greater trust in their own driving ability over vehicle technology. They expressed that novice drivers should learn to drive on non-ADAS-equipped cars and that ADAS should be considered a supplemental aid. Many teens felt that overreliance on ADAS may increase distracted driving or risky behaviors among teens. Parents also

Factors Contributing to Crashes among Young Drivers

Directory of Open Access Journals (Sweden)

Lyndel J. Bates

2014-08-01

Full Text Available Young drivers are the group of drivers most likely to crash. There are a number of factors that contribute to the high crash risk experienced by these drivers. While some of these factors are intrinsic to the young driver, such as their age, gender or driving skill, others relate to social factors and when and how often they drive. This article reviews the factors that affect the risk of young drivers crashing to enable a fuller understanding of why this risk is so high in order to assist in developing effective countermeasures.

Important information for drivers in France

CERN Multimedia

2012-01-01

From 1 July 2012, any driver of a motorised road vehicle, excluding two- or three-wheeled vehicles whose engine capacity does not exceed 50cm3, must be in possession of a breathalyser in full working order. With effect from 1 November 2012*, drivers failing to produce a breathalyser run the risk of being served with an 11 euro fine. A breathalyser is used to measure the alcohol content in the motorist's breath. The permissible level of alcohol for drivers is less than 0.5 g of alcohol per litre of blood, or 0.25 mg of alcohol per litre of air exhaled. The obligation to have a breathalyser on board the vehicle also applies to all drivers on the French part of the CERN site. All vehicles belonging to or leased by the Organization must also carry a breathalyser together with all the requisite documentation (cf. Operational Circular No. 4). Drivers of privately owned vehicles can obtain breathalysers from car accessory dealers, service stations or pharmacies, etc. Drivers of vehicles belonging to or l...

Two-dimensional optoelectronic interconnect-processor and its operational bit error rate

Science.gov (United States)

Liu, J. Jiang; Gollsneider, Brian; Chang, Wayne H.; Carhart, Gary W.; Vorontsov, Mikhail A.; Simonis, George J.; Shoop, Barry L.

2004-10-01

Two-dimensional (2-D) multi-channel 8x8 optical interconnect and processor system were designed and developed using complementary metal-oxide-semiconductor (CMOS) driven 850-nm vertical-cavity surface-emitting laser (VCSEL) arrays and the photodetector (PD) arrays with corresponding wavelengths. We performed operation and bit-error-rate (BER) analysis on this free-space integrated 8x8 VCSEL optical interconnects driven by silicon-on-sapphire (SOS) circuits. Pseudo-random bit stream (PRBS) data sequence was used in operation of the interconnects. Eye diagrams were measured from individual channels and analyzed using a digital oscilloscope at data rates from 155 Mb/s to 1.5 Gb/s. Using a statistical model of Gaussian distribution for the random noise in the transmission, we developed a method to compute the BER instantaneously with the digital eye-diagrams. Direct measurements on this interconnects were also taken on a standard BER tester for verification. We found that the results of two methods were in the same order and within 50% accuracy. The integrated interconnects were investigated in an optoelectronic processing architecture of digital halftoning image processor. Error diffusion networks implemented by the inherently parallel nature of photonics promise to provide high quality digital halftoned images.

Psychological influences for the driver by the changes of running circumstance; Jidosha no soko kankyo henka no driver eno shinriteki eikyo

Energy Technology Data Exchange (ETDEWEB)

Okura, S; Yokomori, M; Yamaguchi, S [Meijo University, Nagoya (Japan)

1997-10-01

A driver is influenced psychologically by the cars proceeding on the street and the cars parked on the shoulder which come into the front view. The traffic accidents are caused when these influences put a lot of stress on a driver. In this report, we study the relations between the road traffic condition on the streets and the highway and the driver`s psychological and psysiological responses by using the driver`s front view, sweating and pulse rate. 6 refs., 8 figs.

School Bus Accidents and Driver Age.

Science.gov (United States)

McMichael, Judith

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

78 FR 76757 - Regulatory Guidance on Hours of Service of Drivers Rest Break Requirement; Drivers Who Become...

Science.gov (United States)

2013-12-19

... limitations for unforeseen reasons, is the driver in violation of the Sec. 395.3 rest break provision if more... unforeseen reasons, is not in violation of the Sec. 395.3 rest-break requirements if 8 or more hours have... Regulatory Guidance on Hours of Service of Drivers Rest Break Requirement; Drivers Who Become Ineligible for...

Terrestrial and extraterrestrial superresonators as drivers for an inertial confinement fusion reactor

International Nuclear Information System (INIS)

Seifritz, W.; Vath, W.

1992-01-01

This paper reports on the recirculating power fraction of a laser-driven inertial confinement fusion (ICF) reactor which can be reduced by using laser diodes to pump a neodymium solid-state laser. To overcome the high costs of two-dimensional arrays of laser diodes, two types of superresonators are proposed: a terrestrially based one and an extraterrestrially based one on a geostationary orbit. Both are designed in such a way that a sequence of short laser pulses (10 to 20 ns wide), each with an energy of 5 to 10 MJ and a frequency of 10 Hz, are produced to trigger a deuterium-tritium ICF reactor. The terrestrial superresonator needs a much smaller number of two-dimensional laser diode arrays than a conventionally pumped once-through solid-state laser system, and the extraterrestrial resonator is pumped by means of concentrated solar radiation. In practice, at least an order of magnitude fewer laser diodes and crystalline calcium fluoride gain media are needed to meet the requirements of a laser driver for an ICF reactor. If, finally, a liquid neodymium laser system could be used for an ICF reactor, the cooling of the gain slabs would be facilitated substantially

Demonstration of a III-nitride vertical-cavity surface-emitting laser with a III-nitride tunnel junction intracavity contact

International Nuclear Information System (INIS)

Leonard, J. T.; Young, E. C.; Yonkee, B. P.; Cohen, D. A.; Margalith, T.; Speck, J. S.; DenBaars, S. P.; Nakamura, S.

2015-01-01

We report on a III-nitride vertical-cavity surface-emitting laser (VCSEL) with a III-nitride tunnel junction (TJ) intracavity contact. The violet nonpolar VCSEL employing the TJ is compared to an equivalent VCSEL with a tin-doped indium oxide (ITO) intracavity contact. The TJ VCSEL shows a threshold current density (J th ) of ∼3.5 kA/cm 2 , compared to the ITO VCSEL J th of 8 kA/cm 2 . The differential efficiency of the TJ VCSEL is also observed to be significantly higher than that of the ITO VCSEL, reaching a peak power of ∼550 μW, compared to ∼80 μW for the ITO VCSEL. Both VCSELs display filamentary lasing in the current aperture, which we believe to be predominantly a result of local variations in contact resistance, which may induce local variations in refractive index and free carrier absorption. Beyond the analyses of the lasing characteristics, we discuss the molecular-beam epitaxy (MBE) regrowth of the TJ, as well as its unexpected performance based on band-diagram simulations. Furthermore, we investigate the intrinsic advantages of using a TJ intracavity contact in a VCSEL using a 1D mode profile analysis to approximate the threshold modal gain and general loss contributions in the TJ and ITO VCSEL

Demonstration of a III-nitride vertical-cavity surface-emitting laser with a III-nitride tunnel junction intracavity contact

Energy Technology Data Exchange (ETDEWEB)

Leonard, J. T., E-mail: jtleona01@gmail.com; Young, E. C.; Yonkee, B. P.; Cohen, D. A.; Margalith, T.; Speck, J. S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); DenBaars, S. P.; Nakamura, S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)

2015-08-31

We report on a III-nitride vertical-cavity surface-emitting laser (VCSEL) with a III-nitride tunnel junction (TJ) intracavity contact. The violet nonpolar VCSEL employing the TJ is compared to an equivalent VCSEL with a tin-doped indium oxide (ITO) intracavity contact. The TJ VCSEL shows a threshold current density (J{sub th}) of ∼3.5 kA/cm{sup 2}, compared to the ITO VCSEL J{sub th} of 8 kA/cm{sup 2}. The differential efficiency of the TJ VCSEL is also observed to be significantly higher than that of the ITO VCSEL, reaching a peak power of ∼550 μW, compared to ∼80 μW for the ITO VCSEL. Both VCSELs display filamentary lasing in the current aperture, which we believe to be predominantly a result of local variations in contact resistance, which may induce local variations in refractive index and free carrier absorption. Beyond the analyses of the lasing characteristics, we discuss the molecular-beam epitaxy (MBE) regrowth of the TJ, as well as its unexpected performance based on band-diagram simulations. Furthermore, we investigate the intrinsic advantages of using a TJ intracavity contact in a VCSEL using a 1D mode profile analysis to approximate the threshold modal gain and general loss contributions in the TJ and ITO VCSEL.

Driver-centred vehicle automation: using network analysis for agent-based modelling of the driver in highly automated driving systems.

Science.gov (United States)

Banks, Victoria A; Stanton, Neville A

2016-11-01

To the average driver, the concept of automation in driving infers that they can become completely 'hands and feet free'. This is a common misconception, however, one that has been shown through the application of Network Analysis to new Cruise Assist technologies that may feature on our roads by 2020. Through the adoption of a Systems Theoretic approach, this paper introduces the concept of driver-initiated automation which reflects the role of the driver in highly automated driving systems. Using a combination of traditional task analysis and the application of quantitative network metrics, this agent-based modelling paper shows how the role of the driver remains an integral part of the driving system implicating the need for designers to ensure they are provided with the tools necessary to remain actively in-the-loop despite giving increasing opportunities to delegate their control to the automated subsystems. Practitioner Summary: This paper describes and analyses a driver-initiated command and control system of automation using representations afforded by task and social networks to understand how drivers remain actively involved in the task. A network analysis of different driver commands suggests that such a strategy does maintain the driver in the control loop.

Tracking progress in teenage driver crash risk in the United States since the advent of graduated driver licensing programs.

Science.gov (United States)

McCartt, Anne T; Teoh, Eric R

2015-06-01

This study examined U.S. teenagers' crash rates since 1996, when the first graduated driver licensing (GDL) program in the United State was implemented. Passenger vehicle driver crash involvement rates for 16-19 and 30-59 (middle-aged) year-olds were examined, using data from the Fatality Analysis Reporting System, National Automotive Sampling System General Estimates System, Census Bureau, and National Household Travel Surveys. Per capita fatal and police-reported crash rates in 2012 were lower for 16year-olds than for middle-aged drivers but older teenagers' rates were higher. Mileage-based fatal and police-reported crash rates in 2008 were higher for teenagers than for middle-aged drivers and higher for 16-17year-olds than for older teenagers. In 1996-2012, teenagers' per capita fatal and police-reported crash rates declined sharply, especially for 16-17year-olds, and more so than for middle-aged drivers. Substantial declines also occurred in teenagers' mileage-based fatal and police-reported crash rates from 1995-96 to 2008, generally more so than for middle-aged drivers. Regarding factors in fatal crashes in 1996 and 2012, proportions of young teenagers' crashes occurring at night and with multiple teenage passengers declined, more so than among older teenagers and middle-aged drivers. The proportion of fatally injured drivers who had been drinking declined for teenagers but changed little for middle-aged drivers. Improvements were not apparent in rates of driver errors or speeding among teenage drivers in fatal crashes. Teenage drivers' crash risk dropped during the period of implementation of GDL laws, especially fatal crash types targeted by GDL. However, teenagers' crash risk remains high, and important crash factors remain unaddressed by GDL. Although this study was not designed to examine the role of GDL, the results are consistent with the increased presence of such laws. More gains are achievable if states strengthen their laws. Copyright © 2015

Research on driver fatigue detection

Science.gov (United States)

Zhang, Ting; Chen, Zhong; Ouyang, Chao

2018-03-01

Driver fatigue is one of the main causes of frequent traffic accidents. In this case, driver fatigue detection system has very important significance in avoiding traffic accidents. This paper presents a real-time method based on fusion of multiple facial features, including eye closure, yawn and head movement. The eye state is classified as being open or closed by a linear SVM classifier trained using HOG features of the detected eye. The mouth state is determined according to the width-height ratio of the mouth. The head movement is detected by head pitch angle calculated by facial landmark. The driver's fatigue state can be reasoned by the model trained by above features. According to experimental results, drive fatigue detection obtains an excellent performance. It indicates that the developed method is valuable for the application of avoiding traffic accidents caused by driver's fatigue.

Study on driving control behavior for lane change maneuver. Analysis of expert driver using neural network system; Shasen henkoji no driver sosa tokusei. Neural network system ni yoru jukuren driver no kaiseki

Energy Technology Data Exchange (ETDEWEB)

Yang, Z; Okayama, T; Katayama, T [Japan Automobile Research Institute Inc., Tsukuba (Japan); Kageyama, I [Nihon University, Tokyo (Japan)

1997-10-01

In order to study driver steering control behavior for vehicle, a driver model for single-lane change maneuver is constructed by a neural network system concerned with the man-machine-environment system. And, using sensitivity analysis, it is found that the model represent the driver control behavior, and the relation between the driver control behavior and vehicle responses. The sensitivity analysis is also examined by applying to the 2nd order predictive driver model. The validity of the sensitivity analysis is confirmed. 5 refs., 8 figs.

A Simple Wave Driver

Science.gov (United States)

Temiz, Burak Kagan; Yavuz, Ahmet

2015-01-01

This study was done to develop a simple and inexpensive wave driver that can be used in experiments on string waves. The wave driver was made using a battery-operated toy car, and the apparatus can be used to produce string waves at a fixed frequency. The working principle of the apparatus is as follows: shortly after the car is turned on, the…

Do young novice drivers overestimate their driving skills more than experienced drivers? : different methods lead to different conclusions.

NARCIS (Netherlands)

Craen, S. de Twisk, D.A.M. Hagenzieker, M.P. Elffers, H. & Brookhuis, K.A.

2011-01-01

In this study the authors argue that drivers have to make an assessment of their own driving skills, in order to sufficiently adapt to their task demands in traffic. There are indications that drivers in general, but novice drivers in particular, overestimate their driving skills. However, study

[Occupational stress situation analysis of different types of train drivers].

Science.gov (United States)

Zhou, Wenhui; Gu, Guizhen; Wu, Hui; Yu, Shanfa

2014-11-01

To analyze the status of occupational stress in different types of train drivers. By using cluster sampling method, a cross-sectional study was conducted in 1 339 train drivers (including 289 passenger train drivers, 637 freight trains drivers, 339 passenger shunting train drivers, and 74 high speed rail drivers) from a Railway Bureau depot. The survey included individual factors, occupational stress factors, stress response factors and stress mitigating factors. The occupational stress factors, stress response factors and mitigating factors were measured by the revised effort-reward imbalance (ERI) model questionnaires and occupational stress measurement scale. By using the method of covariance analysized the difference of occupational stress factors of all types train drivers, the method of Stepwise regression was used to analyze the effection (R(2)) of occupational stress factors and stress mitigating factors on stress response factors. Covariance analysis as covariates in age, education level, length of service and marital status showed that the scores of ERI (1.58 ± 0.05), extrinsic effort (19.88 ± 0.44), rewards (23.43 ± 0.43), intrinsic effort (17.86 ± 0.36), physical environment (5.70 ± 0.22), social support (30.51 ± 0.88) and daily tension (10.27 ± 0.38 ) of high speed rail drivers were higher than other drivers (F values were 6.06, 11.32, 7.05, 13.25, 5.20, 9.48 and 6.14 respectively, P occupational stress factors and mitigating factors to depressive symptoms of train drivers was high speed rail drivers (R(2) = 0.64), passenger train drivers (R(2) = 0.44), passenger shunting train drivers (R(2) = 0.39), freight trains drivers (R(2) = 0.38); job satisfaction of train drivers was high speed rail drivers (R(2) = 0.68), passenger train drivers (R(2) = 0.62), freight trains drivers (R(2) = 0.43), passenger shunting train drivers(R(2) = 0.38); to daily tension of train drivers was high speed rail drivers (R(2) = 0.54), passenger train drivers (R(2) = 0

Reliability of drivers in urban intersections.

Science.gov (United States)

Gstalter, Herbert; Fastenmeier, Wolfgang

2010-01-01

The concept of human reliability has been widely used in industrial settings by human factors experts to optimise the person-task fit. Reliability is estimated by the probability that a task will successfully be completed by personnel in a given stage of system operation. Human Reliability Analysis (HRA) is a technique used to calculate human error probabilities as the ratio of errors committed to the number of opportunities for that error. To transfer this notion to the measurement of car driver reliability the following components are necessary: a taxonomy of driving tasks, a definition of correct behaviour in each of these tasks, a list of errors as deviations from the correct actions and an adequate observation method to register errors and opportunities for these errors. Use of the SAFE-task analysis procedure recently made it possible to derive driver errors directly from the normative analysis of behavioural requirements. Driver reliability estimates could be used to compare groups of tasks (e.g. different types of intersections with their respective regulations) as well as groups of drivers' or individual drivers' aptitudes. This approach was tested in a field study with 62 drivers of different age groups. The subjects drove an instrumented car and had to complete an urban test route, the main features of which were 18 intersections representing six different driving tasks. The subjects were accompanied by two trained observers who recorded driver errors using standardized observation sheets. Results indicate that error indices often vary between both the age group of drivers and the type of driving task. The highest error indices occurred in the non-signalised intersection tasks and the roundabout, which exactly equals the corresponding ratings of task complexity from the SAFE analysis. A comparison of age groups clearly shows the disadvantage of older drivers, whose error indices in nearly all tasks are significantly higher than those of the other groups

Schoolbus driver performance can be improved with driver training, safety incentivisation, and vehicle roadworthy modifications

Directory of Open Access Journals (Sweden)

A van Niekerk

2017-03-01

Full Text Available In South Africa (SA, the school transport industry provides millions of children with a means of travelling to and from school. The industry has, however, been reported to be plagued by widespread safety concerns. The consequent road traffic incidents have often been attributed to driver factors, including driving in excess of legal speeds or at inappropriate speeds; driving while under the influence of alcohol, while sleepy or fatigued; or driving without using protective equipment for vehicle occupants. There are currently very few SA interventions that specifically target this important industry role-player. The Safe Travel to School Programme was recently implemented by a national child safety agency, with a focus on driver road safety awareness, defensive driver training, eye- testing, vehicle roadworthy inspections with selected upgrades, incentives for safe performance, and implementation of a vehicle telematics tracking system with regular, individual driving behaviour information updates. This quasi-experimental study offers an evaluation of the initial impact on safety performance of this telematics-based driver and vehicle safety intervention in terms of speeding, acceleration, braking, cornering, and time-of-day driving, and compares the school transport driver performance with that of general motorists. Despite concerns that some school transport vehicles are used for multiple purposes outside of school transport duties, at night, and for longer distances, overall these vehicles recorded lower percentages of speeding, lower harsh braking, and lower average harsh cornering and acceleration than general drivers.

20 CFR 404.1008 - Agent-driver or commission-driver, full-time life insurance salesman, home worker, or traveling...

Science.gov (United States)

2010-04-01

... commission-driver, full-time life insurance salesman, home worker, or traveling or city salesman. (a) General... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Agent-driver or commission-driver, full-time life insurance salesman, home worker, or traveling or city salesman. 404.1008 Section 404.1008...

among Taxi Drivers in Addis Ababa, Ethiopia

African Journals Online (AJOL)

user

Long years of driving [AOR =4.6 (95%CI, 1.6-12.9)], involvement in a similar activity prior to becoming taxi driver .... full time taxi driver; produce a valid driving license; .... Self-employee .... professional car drivers in Dhaka city, Bangladesh.

A holistic perspective on corporate sustainability drivers

NARCIS (Netherlands)

Lozano, R.

2013-01-01

Since company boards are increasingly discussing 'sustainability', it becomes necessary to examine the nature of sustainability drivers. Most approaches to corporate sustainability drivers have focused either on internal or external drivers. This paper is aimed at providing a more holistic

A holistic perspective on corporate sustainability drivers

NARCIS (Netherlands)

Lozano, Rodrigo|info:eu-repo/dai/nl/36412380X

2015-01-01

Since company boards are increasingly discussing 'sustainability', it becomes necessary to examine the nature of sustainability drivers. Most approaches to corporate sustainability drivers have focused either on internal or external drivers. This paper is aimed at providing a more holistic

Naturalistic distraction and driving safety in older drivers.

Science.gov (United States)

Aksan, Nazan; Dawson, Jeffrey D; Emerson, Jamie L; Yu, Lixi; Uc, Ergun Y; Anderson, Steven W; Rizzo, Matthew

2013-08-01

In this study, we aimed to quantify and compare performance of middle-aged and older drivers during a naturalistic distraction paradigm (visual search for roadside targets) and to predict older drivers performance given functioning in visual, motor, and cognitive domains. Distracted driving can imperil healthy adults and may disproportionally affect the safety of older drivers with visual, motor, and cognitive decline. A total of 203 drivers, 120 healthy older (61 men and 59 women, ages 65 years and older) and 83 middle-aged drivers (38 men and 45 women, ages 40 to 64 years), participated in an on-road test in an instrumented vehicle. Outcome measures included performance in roadside target identification (traffic signs and restaurants) and concurrent driver safety. Differences in visual, motor, and cognitive functioning served as predictors. Older drivers identified fewer landmarks and drove slower but committed more safety errors than did middle-aged drivers. Greater familiarity with local roads benefited performance of middle-aged but not older drivers.Visual cognition predicted both traffic sign identification and safety errors, and executive function predicted traffic sign identification over and above vision. Older adults are susceptible to driving safety errors while distracted by common secondary visual search tasks that are inherent to driving. The findings underscore that age-related cognitive decline affects older drivers' management of driving tasks at multiple levels and can help inform the design of on-road tests and interventions for older drivers.

Kalman filter-based tracking of moving objects using linear ultrasonic sensor array for road vehicles

Science.gov (United States)

Li, Shengbo Eben; Li, Guofa; Yu, Jiaying; Liu, Chang; Cheng, Bo; Wang, Jianqiang; Li, Keqiang

2018-01-01

Detection and tracking of objects in the side-near-field has attracted much attention for the development of advanced driver assistance systems. This paper presents a cost-effective approach to track moving objects around vehicles using linearly arrayed ultrasonic sensors. To understand the detection characteristics of a single sensor, an empirical detection model was developed considering the shapes and surface materials of various detected objects. Eight sensors were arrayed linearly to expand the detection range for further application in traffic environment recognition. Two types of tracking algorithms, including an Extended Kalman filter (EKF) and an Unscented Kalman filter (UKF), for the sensor array were designed for dynamic object tracking. The ultrasonic sensor array was designed to have two types of fire sequences: mutual firing or serial firing. The effectiveness of the designed algorithms were verified in two typical driving scenarios: passing intersections with traffic sign poles or street lights, and overtaking another vehicle. Experimental results showed that both EKF and UKF had more precise tracking position and smaller RMSE (root mean square error) than a traditional triangular positioning method. The effectiveness also encourages the application of cost-effective ultrasonic sensors in the near-field environment perception in autonomous driving systems.

OLDER DRIVERS AND ADAS

Directory of Open Access Journals (Sweden)

Ragnhild J. DAVIDSE

2006-01-01

Next, based on the available literature, relevant ADAS are discussed in terms of their availability, their effects on safety and the willingness of older drivers to use and buy them. One of the conclusions is that only very few of the types of support that are thought to be most beneficial to the safety of older drivers are provided by the ADAS that are currently available.

Truck Drivers And Risk Of STDs Including HIV

Directory of Open Access Journals (Sweden)

Bansal R.K

1995-01-01

Full Text Available Research Question: Whether long distance truck drivers are at a higher risk of contracting and transmitting STDs including HIV? Objectives: i To study the degree of knowledge of HIV and AIDS among long- distance truck drivers. ii Assess their sexual behaviour including condom use. iii Explore their prevailing social influences and substance abuse patterns. iv Explore their treatment seeking bahaviour as regards STDs. v Deduce their risk of contracting and transmitting STDs including HIV. Study Design: Cross- sectional interview. Setting: Transport Nagar, Indore (M.P Participants: 210 senior drivers (First drivers and 210 junior drivers (Second drivers. Study Variables: Extra-Marital sexual intercourse, condom usage, past and present history of STDs, treatment and counseling, substance abuse, social â€" cultural milieu. Outcome Variables: Risk of contraction of STDs. Statistical Analysis: Univariate analysis. Results: 94% of the drivers were totally ignorant about AIDS. 82.9% and 43.8 % of the senior and junior drivers had a history of extra- marital sex and of these only 2 regularly used condoms. 13.8% and 3.3 % of the senior and junior drivers had a past or present history suggestive of STD infection. Alcohol and Opium were regularly used by them. Conclusion: The studied drivers are at a high risk of contracting and transmitting STDs including HIV.

Sexual behavior among truck drivers.

Science.gov (United States)

Singh, Rajiv Kumar; Joshi, Hari Shankar

2012-01-01

A cross-sectional study was conducted on Lucknow highway in Bareilly district of Uttar Pradesh to study the knowledge of truck drivers about HIV transmission and prevention and to study the sexual behaviour of these drivers with reference to HIV/AIDS. Age, marital status, education, income, drinking alcohol, length of stay away from home, knowledge about transmission and prevention of HIV, and HIV-prone behavior of truck drivers were studied. Chi-square, mean, and SD were calculated. In all, 289 (97.6%) drivers had heard about HIV/AIDS. Only 242 (81.8%) were aware of HIV transmission by heterosexual route. Misconceptions such as HIV transmission by mosquito bites, living in same room, shaking hands, and sharing food were found. Out of 174 (58.8%) who visited Commercial Sex Workers (CSW), 146 (83.9%) used a condom. 38 (12.8%) visited more than 5 CSW in the last 3 months. Time away from home on the road, marital status, alcohol use, and income class were associated with visiting CSW. High-risk behavior was established in the study population. Safe sex and use of condoms need to be promoted among the truck drivers and better condom availability needs to be assured on highways.

Compliance with driver's license laws and illegal licensing among commercial bus drivers in Lagos, Nigeria: policy implications and evidence for action.

Science.gov (United States)

Okafor, I P; Odeyemi, K A; Dolapo, D C; Adegbola, A A

2014-09-01

To determine the level of compliance with driver's license laws among commercial bus drivers in Lagos, Nigeria. Two intercity motor parks were selected by simple random sampling and all consenting minibus drivers participated in the study. Key Informant Interviews (KIIs) were also conducted with selected officials in the driver training and licensing authorities. Compliance with the minimum age for driving was high (93.6%), so also was having driving test prior to driver's license procurement (83.3%). Formal driver training and VA testing were very low, (26.1% and 32.9% respectively) Overall, only 9.3% of them were found to have fulfilled all the pre-license obligations before obtaining their first driver's license. The odds of a driver with a secondary education having formal driver training is 3.33 times higher than those with no education (OR 3.33, 95% CI 1.01-11.35). Drivers who were 60 years or older were 3.62 times more likely to be compliant than those who were between 20-29 years (OR 3.62, 95% CI 0.56-29.19). For the 98.3% of them who possessed valid licenses, 52.3% of them obtained them illegally. All the key officials saw RTIs as a serious public health problem but faced several challenges in the course of their work. Overall compliance with pre-license regulations was very poor. There is need for a review and strict enforcement of driver's license laws to improve compliance. Also vital are fostering inter-sectoral collaboration and improvement in the operations of all establishments involved in driver training and license procurement in Nigeria.

Driver steering model for closed-loop steering function analysis

Science.gov (United States)

Bolia, Pratiksh; Weiskircher, Thomas; Müller, Steffen

2014-05-01

In this paper, a two level preview driver steering control model for the use in numerical vehicle dynamics simulation is introduced. The proposed model is composed of cascaded control loops: The outer loop is the path following layer based on potential field framework. The inner loop tries to capture the driver's physical behaviour. The proposed driver model allows easy implementation of different driving situations to simulate a wide range of different driver types, moods and vehicle types. The expediency of the proposed driver model is shown with the help of developed driver steering assist (DSA) function integrated with a conventional series production (Electric Power steering System with rack assist servo unit) system. With the help of the DSA assist function, the driver is prevented from over saturating the front tyre forces and loss of stability and controllability during cornering. The simulation results show different driver reactions caused by the change in the parameters or properties of the proposed driver model if the DSA assist function is activated. Thus, the proposed driver model is useful for the advanced driver steering and vehicle stability assist function evaluation in the early stage of vehicle dynamics handling and stability evaluation.

An examination of the environmental, driver and vehicle factors associated with the serious and fatal crashes of older rural drivers.

Science.gov (United States)

Thompson, J P; Baldock, M R J; Mathias, J L; Wundersitz, L N

2013-01-01

Motor vehicle crashes involving rural drivers aged 75 years and over are more than twice as likely to result in a serious or fatal injury as those involving their urban counterparts. The current study examined some of the reasons for this using a database of police-reported crashes (2004-2008) to identify the environmental (lighting, road and weather conditions, road layout, road surface, speed limit), driver (driver error, crash type), and vehicle (vehicle age) factors that are associated with the crashes of older rural drivers. It also determined whether these same factors are associated with an increased likelihood of serious or fatal injury in younger drivers for whom frailty does not contribute to the resulting injury severity. A number of environmental (i.e., undivided, unsealed, curved and inclined roads, and areas with a speed limit of 100km/h or greater) and driver (i.e., collision with a fixed object and rolling over) factors were more frequent in the crashes of older rural drivers and additionally associated with increased injury severity in younger drivers. Moreover, when these environmental factors were entered into a logistic regression model to predict whether older drivers who were involved in crashes did or did not sustain a serious or fatal injury, it was found that each factor independently increased the likelihood of a serious or fatal injury. Changes, such as the provision of divided and sealed roads, greater protection from fixed roadside objects, and reduced speed limits, appear to be indicated in order to improve the safety of the rural driving environment for drivers of all ages. Additionally, older rural drivers should be encouraged to reduce their exposure to these risky circumstances. Copyright © 2012 Elsevier Ltd. All rights reserved.

Using shadow page cache to improve isolated drivers performance.

Science.gov (United States)

Zheng, Hao; Dong, Xiaoshe; Wang, Endong; Chen, Baoke; Zhu, Zhengdong; Liu, Chengzhe

2015-01-01

With the advantage of the reusability property of the virtualization technology, users can reuse various types and versions of existing operating systems and drivers in a virtual machine, so as to customize their application environment. In order to prevent users' virtualization environments being impacted by driver faults in virtual machine, Chariot examines the correctness of driver's write operations by the method of combining a driver's write operation capture and a driver's private access control table. However, this method needs to keep the write permission of shadow page table as read-only, so as to capture isolated driver's write operations through page faults, which adversely affect the performance of the driver. Based on delaying setting frequently used shadow pages' write permissions to read-only, this paper proposes an algorithm using shadow page cache to improve the performance of isolated drivers and carefully study the relationship between the performance of drivers and the size of shadow page cache. Experimental results show that, through the shadow page cache, the performance of isolated drivers can be greatly improved without impacting Chariot's reliability too much.

Education for older drivers in the future

Directory of Open Access Journals (Sweden)

Esko Keskinen

2014-07-01

Five presumptions have to be considered when addressing future education for older drivers: 1. Driving a car will continue to be one element of mobility in the future; 2. Older people want to be able to keep driving; 3. Safety will be an even more important factor in mobility in the future; 4. Ecological values will be more important in the future; and 5. Innovative technological applications will be more important in the future. Hierarchical models of driving are suitable in increasing understanding of older drivers' needs and abilities. The highest levels of the driving hierarchy in the Goals for Driver Education (GDE model are especially important for the safety of both young and elderly drivers. In these highest levels goals for life, skills for living, and social environment affect everyday decision making in general but also driving, which has an impact on driver safety. Giving up driving is very much a social decision and should be taken as such. However, the highest levels of the driving hierarchy are by nature inaccessible to teacher-centered instruction These levels require more coaching-like education methods where the learner takes the central role and the teacher helps the drivers understand their own abilities and limitations in traffic. Testing and selecting older drivers to enhance safety is not, according to research findings, working in a proper way. Older drivers do not so much need more information concerning traffic rules, etc., but rather better understanding of themselves, their health restrictions, their skills, and their abilities to ensure daily mobility. Their closest companions also need tools to help them in discussions of traffic safety issues affecting older drivers.

Focal plane array with modular pixel array components for scalability

Science.gov (United States)

Kay, Randolph R; Campbell, David V; Shinde, Subhash L; Rienstra, Jeffrey L; Serkland, Darwin K; Holmes, Michael L

2014-12-09

A modular, scalable focal plane array is provided as an array of integrated circuit dice, wherein each die includes a given amount of modular pixel array circuitry. The array of dice effectively multiplies the amount of modular pixel array circuitry to produce a larger pixel array without increasing die size. Desired pixel pitch across the enlarged pixel array is preserved by forming die stacks with each pixel array circuitry die stacked on a separate die that contains the corresponding signal processing circuitry. Techniques for die stack interconnections and die stack placement are implemented to ensure that the desired pixel pitch is preserved across the enlarged pixel array.

The importance of sight for drivers

Directory of Open Access Journals (Sweden)

Alicja Pas-Wyroślak

2013-06-01

Full Text Available Sight is the basic sense for drivers. Condition of the eye determines correct, comfortable and safe performance of the work as drivers. This article presents various factors influencing the sight condition. There are two groups of factors, external (environment, the kind and time of work, stress caused by work and internal (systemic and local disorders. All these factors can reduce significantly visual functions, such as visual acuity, field of vision, color vision, strereoscopic vision, twilight vision and glare sensitivity. There are also presented actual requirements for drivers and causes of the car accidents in various age groups. Impairments in vision functions can be dangerous for both the driver and other road users. Med Pr 2013;64(3:419–425

Redesign of Transjakarta Bus Driver's Cabin

Science.gov (United States)

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

2016-02-01

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

Workshop on transport for a common ion driver

International Nuclear Information System (INIS)

Olson, C.C.; Lee, E.; Langdon, B.

1994-01-01

This report contains research in the following areas related to beam transport for a common ion driver: multi-gap acceleration; neutralization with electrons; gas neutralization; self-pinched transport; HIF and LIF transport, and relevance to common ion driver; LIF and HIF reactor concepts and relevance to common ion driver; atomic physics for common ion driver; code capabilities and needed improvement

Ultrahigh speed endoscopic swept source optical coherence tomography using a VCSEL light source and micromotor catheter

Science.gov (United States)

Tsai, Tsung-Han; Ahsen, Osman O.; Lee, Hsiang-Chieh; Liang, Kaicheng; Giacomelli, Michael G.; Potsaid, Benjamin M.; Tao, Yuankai K.; Jayaraman, Vijaysekhar; Kraus, Martin F.; Hornegger, Joachim; Figueiredo, Marisa; Huang, Qin; Mashimo, Hiroshi; Cable, Alex E.; Fujimoto, James G.

2014-03-01

We developed an ultrahigh speed endoscopic swept source optical coherence tomography (OCT) system for clinical gastroenterology using a vertical-cavity surface-emitting laser (VCSEL) and micromotor based imaging catheter, which provided an imaging speed of 600 kHz axial scan rate and 8 μm axial resolution in tissue. The micromotor catheter was 3.2 mm in diameter and could be introduced through the 3.7 mm accessory port of an endoscope. Imaging was performed at 400 frames per second with an 8 μm spot size using a pullback to generate volumetric data over 16 mm with a pixel spacing of 5 μm in the longitudinal direction. Three-dimensional OCT (3D-OCT) imaging was performed in patients with a cross section of pathologies undergoing standard upper and lower endoscopy at the Veterans Affairs Boston Healthcare System (VABHS). Patients with Barrett's esophagus, dysplasia, and inflammatory bowel disease were imaged. The use of distally actuated imaging catheters allowed OCT imaging with more flexibility such as volumetric imaging in the terminal ileum and the assessment of the hiatal hernia using retroflex imaging. The high rotational stability of the micromotor enabled 3D volumetric imaging with micron scale volumetric accuracy for both en face and cross-sectional imaging. The ability to perform 3D OCT imaging in the GI tract with microscopic accuracy should enable a wide range of studies to investigate the ability of OCT to detect pathology as well as assess treatment response.

Driver training in steps (DTS).

NARCIS (Netherlands)

2010-01-01

For some years now, it has been possible in the Netherlands to follow a Driver Training in Steps (DTS) as well as the regular driver training. The DTS is a structured training method with clear training objectives which are categorized in four modules. Although the DTS is considerably better than

Drivers of change in estuarine-coastal ecosystems: Discoveries from four decades of study in San Francisco Bay

Science.gov (United States)

Cloern, J.E.; Jassby, A.D.

2012-01-01

Poised at the interface of rivers, ocean, atmosphere and dense human settlement, estuaries are driven by a large array of natural and anthropogenic forces. San Francisco Bay exemplifies the fast-paced change occurring in many of the world's estuaries, bays and inland seas in response to these diverse forces. We use observations from this particularly well-studied estuary to illustrate responses to six drivers that are common agents of change where land and sea meet: water consumption and diversion; human modification of sediment supply; introduction of non-native species; sewage input; environmental policy; and climate shifts. In San Francisco Bay, responses to these drivers include, respectively, shifts in the timing and extent of freshwater inflow and salinity intrusion; decreasing turbidity; restructuring of plankton communities; nutrient enrichment; elimination of hypoxia and reduced metal contamination of biota; and food web changes that decrease resistance of the estuary to nutrient pollution. Detection of these changes and discovery of their causes through environmental monitoring have been essential for establishing and measuring outcomes of environmental policies that aim to maintain high water quality and sustain services provided by estuarine-coastal ecosystems. The wide range of variability time scales and the multiplicity of interacting drivers place heavy demands on estuarine monitoring programs. But the San Francisco Bay case study illustrates why the imperative for monitoring has never been greater.

Drivers of change in estuarine-coastal ecosystems: Discoveries from four decades of study in San Francisco Bay

Science.gov (United States)

Cloern, James E.; Jassby, Alan D.

2012-12-01

Poised at the interface of rivers, ocean, atmosphere and dense human settlement, estuaries are driven by a large array of natural and anthropogenic forces. San Francisco Bay exemplifies the fast-paced change occurring in many of the world's estuaries, bays, and inland seas in response to these diverse forces. We use observations from this particularly well-studied estuary to illustrate responses to six drivers that are common agents of change where land and sea meet: water consumption and diversion, human modification of sediment supply, introduction of nonnative species, sewage input, environmental policy, and climate shifts. In San Francisco Bay, responses to these drivers include, respectively, shifts in the timing and extent of freshwater inflow and salinity intrusion, decreasing turbidity, restructuring of plankton communities, nutrient enrichment, elimination of hypoxia and reduced metal contamination of biota, and food web changes that decrease resistance of the estuary to nutrient pollution. Detection of these changes and discovery of their causes through environmental monitoring have been essential for establishing and measuring outcomes of environmental policies that aim to maintain high water quality and sustain services provided by estuarine-coastal ecosystems. The many time scales of variability and the multiplicity of interacting drivers place heavy demands on estuarine monitoring programs, but the San Francisco Bay case study illustrates why the imperative for monitoring has never been greater.

Misalignment corrections in optical interconnects

Science.gov (United States)

Song, Deqiang

Optical interconnects are considered a promising solution for long distance and high bitrate data transmissions, outperforming electrical interconnects in terms of loss and dispersion. Due to the bandwidth and distance advantage of optical interconnects, longer links have been implemented with optics. Recent studies show that optical interconnects have clear advantages even at very short distances---intra system interconnects. The biggest challenge for such optical interconnects is the alignment tolerance. Many free space optical components require very precise assembly and installation, and therefore the overall cost could be increased. This thesis studied the misalignment tolerance and possible alignment correction solutions for optical interconnects at backplane or board level. First the alignment tolerance for free space couplers was simulated and the result indicated the most critical alignments occur between the VCSEL, waveguide and microlens arrays. An in-situ microlens array fabrication method was designed and experimentally demonstrated, with no observable misalignment with the waveguide array. At the receiver side, conical lens arrays were proposed to replace simple microlens arrays for a larger angular alignment tolerance. Multilayer simulation models in CodeV were built to optimized the refractive index and shape profiles of the conical lens arrays. Conical lenses fabricated with micro injection molding machine and fiber etching were characterized. Active component VCSOA was used to correct misalignment in optical connectors between the board and backplane. The alignment correction capability were characterized for both DC and AC (1GHz) optical signal. The speed and bandwidth of the VCSOA was measured and compared with a same structure VCSEL. Based on the optical inverter being studied in our lab, an all-optical flip-flop was demonstrated using a pair of VCSOAs. This memory cell with random access ability can store one bit optical signal with set or

Visual behaviour analysis and driver cognitive model

Energy Technology Data Exchange (ETDEWEB)

Baujon, J.; Basset, M.; Gissinger, G.L. [Mulhouse Univ., (France). MIPS/MIAM Lab.

2001-07-01

Recent studies on driver behaviour have shown that perception - mainly visual but also proprioceptive perception - plays a key role in the ''driver-vehicle-road'' system and so considerably affects the driver's decision making. Within the framework of the behaviour analysis and studies low-cost system (BASIL), this paper presents a correlative, qualitative and quantitative study, comparing the information given by visual perception and by the trajectory followed. This information will help to obtain a cognitive model of the Rasmussen type according to different driver classes. Many experiments in real driving situations have been carried out for different driver classes and for a given trajectory profile, using a test vehicle and innovative, specially designed, real-time tools, such as the vision system or the positioning module. (orig.)

SPIDER: A Framework for Understanding Driver Distraction.

Science.gov (United States)

Strayer, David L; Fisher, Donald L

2016-02-01

The objective was to identify key cognitive processes that are impaired when drivers divert attention from driving. Driver distraction is increasingly recognized as a significant source of injuries and fatalities on the roadway. A "SPIDER" model is developed that identifies key cognitive processes that are impaired when drivers divert attention from driving. SPIDER is an acronym standing for scanning, predicting, identifying, decision making, and executing a response. When drivers engage in secondary activities unrelated to the task of driving, SPIDER-related processes are impaired, situation awareness is degraded, and the ability to safely operate a motor vehicle may be compromised. The pattern of interference helps to illuminate the sources of driver distraction and may help guide the integration of new technology into the automobile. © 2015, Human Factors and Ergonomics Society.

Timed arrays wideband and time varying antenna arrays

CERN Document Server

Haupt, Randy L

2015-01-01

Introduces timed arrays and design approaches to meet the new high performance standards The author concentrates on any aspect of an antenna array that must be viewed from a time perspective. The first chapters briefly introduce antenna arrays and explain the difference between phased and timed arrays. Since timed arrays are designed for realistic time-varying signals and scenarios, the book also reviews wideband signals, baseband and passband RF signals, polarization and signal bandwidth. Other topics covered include time domain, mutual coupling, wideband elements, and dispersion. The auth

ArrayBridge: Interweaving declarative array processing with high-performance computing

Energy Technology Data Exchange (ETDEWEB)

Xing, Haoyuan [The Ohio State Univ., Columbus, OH (United States); Floratos, Sofoklis [The Ohio State Univ., Columbus, OH (United States); Blanas, Spyros [The Ohio State Univ., Columbus, OH (United States); Byna, Suren [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Prabhat, Prabhat [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wu, Kesheng [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Brown, Paul [Paradigm4, Inc., Waltham, MA (United States)

2017-05-04

Scientists are increasingly turning to datacenter-scale computers to produce and analyze massive arrays. Despite decades of database research that extols the virtues of declarative query processing, scientists still write, debug and parallelize imperative HPC kernels even for the most mundane queries. This impedance mismatch has been partly attributed to the cumbersome data loading process; in response, the database community has proposed in situ mechanisms to access data in scientific file formats. Scientists, however, desire more than a passive access method that reads arrays from files. This paper describes ArrayBridge, a bi-directional array view mechanism for scientific file formats, that aims to make declarative array manipulations interoperable with imperative file-centric analyses. Our prototype implementation of ArrayBridge uses HDF5 as the underlying array storage library and seamlessly integrates into the SciDB open-source array database system. In addition to fast querying over external array objects, ArrayBridge produces arrays in the HDF5 file format just as easily as it can read from it. ArrayBridge also supports time travel queries from imperative kernels through the unmodified HDF5 API, and automatically deduplicates between array versions for space efficiency. Our extensive performance evaluation in NERSC, a large-scale scientific computing facility, shows that ArrayBridge exhibits statistically indistinguishable performance and I/O scalability to the native SciDB storage engine.

High current, high bandwidth laser diode current driver

Science.gov (United States)

Copeland, David J.; Zimmerman, Robert K., Jr.

1991-01-01

A laser diode current driver has been developed for free space laser communications. The driver provides 300 mA peak modulation current and exhibits an optical risetime of less than 400 ps. The current and optical pulses are well behaved and show minimal ringing. The driver is well suited for QPPM modulation at data rates up to 440 Mbit/s. Much previous work has championed current steering circuits; in contrast, the present driver is a single-ended on/off switch. This results in twice the power efficiency as a current steering driver. The driver electrical efficiency for QPPM data is 34 percent. The high speed switch is realized with a Ku-band GaAsFET transistor, with a suitable pre-drive circuit, on a hybrid microcircuit adjacent to the laser diode.

18- to 24-year-olds : young drivers.

NARCIS (Netherlands)

2016-01-01

The fatality rate (fatalities per distance travelled) of young drivers (18- to 24-year-olds) is more than five times higher than that of drivers between the ages of 30 and 59 years. The fatality rate of young males is even as much as ten times higher. The high risk of young drivers is due to both

Look-ahead driver feedback and powertrain management

Energy Technology Data Exchange (ETDEWEB)

Verma, Rajeev [Eaton Corporation, Menomonee Falls, WI (United States)

2014-12-31

Commercial medium and heavy vehicles, though only a small portion of total vehicle population, play a significant role in energy consumption. In 2012, these vehicles accounted for about 5775.5 trillion btu of energy consumption and 408.8 million tons of CO2 emissions annually, which is a quarter of the total energy burden of highway transportation in the United States [1]. This number is expected to surpass passenger car fuel use within the next few decades. In the meantime, most commercial vehicle fleets are running at a very low profit margin. It is a well known fact that fuel economy can vary significantly between drivers, even when they operate the same vehicle on the same route. According to the US Environmental Protection Agency (EPA) and Natural Resource Canada (NRCan), there is up to 35% fuel economy difference between drivers within the same commercial fleet [2] [3], [4]. Similar results were obtained from a Field Operation Test conducted by Eaton Corporation [5]. During this test as much as 30% fuel economy difference was observed among pick-up-and-delivery drivers and 11% difference was observed among line-haul drivers. The driver variability can be attributed to the fact that different drivers react differently to driving conditions such as road grade, traffic, speed limits, etc. For instance, analysis of over 600k miles of naturalistic heavy duty truck driving data [5] indicates that an experienced driver anticipates a downhill and eases up on the throttle to save fuel while an inexperienced driver lacks this judgment.

Schoolbus driver performance can be improved with driver training ...

African Journals Online (AJOL)

The Safe Travel to School Programme was recently implemented by a national child safety agency, with a focus on driver road safety awareness, defensive ... of a vehicle telematics tracking system with regular, individual driving behaviour ...

Testing a structural model of young driver willingness to uptake Smartphone Driver Support Systems.

Science.gov (United States)

Kervick, Aoife A; Hogan, Michael J; O'Hora, Denis; Sarma, Kiran M

2015-10-01

There is growing interest in the potential value of using phone applications that can monitor driver behaviour (Smartphone Driver Support Systems, 'SDSSs') in mitigating risky driving by young people. However, their value in this regard will only be realised if young people are willing to use this technology. This paper reports the findings of a study in which a novel structural model of willingness to use SDSSs was tested. Grounded in the driver monitoring and Technology Acceptance (TA) research literature, the model incorporates the perceived risks and gains associated with potential SDSS usage and additional social cognitive factors, including perceived usability and social influences. A total of 333 smartphone users, aged 18-24, with full Irish driving licenses completed an online questionnaire examining willingness or Behavioural Intention (BI) to uptake a SDSS. Following exploratory and confirmatory factor analyses, structural equation modelling indicated that perceived gains and social influence factors had significant direct effects on BI. Perceived risks and social influence also had significant indirect effects on BI, as mediated by perceived gains. Overall, this model accounted for 72.5% of the variance in willingness to uptake SDSSs. Multi-group structural models highlighted invariance of effects across gender, high and low risk drivers, and those likely or unlikely to adopt novel phone app technologies. These findings have implications for our understanding of the willingness of young drivers to adopt and use SDSSs, and highlight potential factors that could be targeted in behavioural change interventions seeking to improve usage rates. Copyright © 2015 Elsevier Ltd. All rights reserved.

TRENDS AND ISSUES IN SAFE DRIVER ASSISTANCE SYSTEMS

Directory of Open Access Journals (Sweden)

Sadayuki TSUGAWA

2006-01-01

Full Text Available In recent years, ITS projects in Japan, Europe and the US have been characterized by a strong emphasis on safe driver assistance systems designed to prevent traffic accidents. As it has become clear that eradicating accidents will be impossible by means of vehicle passive safety and single-vehicle active safety efforts alone, research and development of systems for preventing accidents through road-vehicle cooperation and vehicle-vehicle cooperation have been promoted in Japan (ASV, AHS, Europe (PReVENT, SAFESPOT and the US (VII. The key to such technology is road-to-vehicle communications and inter-vehicle communications. On the other hand, a number of driver assistance systems have been brought to market, including lidar-based forward collision warnings, ACC, lane keeping support and drowsiness warnings, but their penetration rates in Japan are extremely low. Furthermore, one major challenge is that safe driver assistance systems based on road-vehicle and vehicle-vehicle cooperation are premised upon a high penetration rate. Finally, we introduce a system for improving driver acceptance of safe driver assistance systems based on driver monitoring and forward monitoring as well as cooperative driver assistance systems for elderly drivers, an issue now receiving attention in Japan.

Older drivers' risks of at-fault motor vehicle collisions.

Science.gov (United States)

Ichikawa, Masao; Nakahara, Shinji; Taniguchi, Ayako

2015-08-01

In aging societies, increasing numbers of older drivers are involved in motor vehicle collisions (MVCs), and preserving their safety is a growing concern. In this study, we focused on whether older drivers were more likely to cause MVCs and injuries than drivers in other age groups. To do so we compared at-fault MVC incidence and resulting injury risks by drivers' ages, using data from Japan, a country with a rapidly aging population. The at-fault MVC incidence was calculated based on distance traveled made for non-commercial purposes, and the injury risks posed to at-fault drivers and other road users per at-fault MVCs. We used MVC data for 2010 from the National Police Agency of Japan and driving exposure data from the Nationwide Person Trip Survey conducted by a Japanese governmental ministry in 2010. The at-fault MVC incidence showed a U-shaped curve across the drivers' ages, where teenage and the oldest drivers appeared to be the highest risk groups in terms of causing MVCs, and the incidence was higher for female drivers after age 25. The injury risk older drivers posed to other vehicle occupants because of their at-fault MVCs was lower than for drivers in other age groups, while their own injury risk appeared much higher. As the number of older drivers is increasing, efforts to reduce their at-fault MVCs appear justified. Copyright © 2015 Elsevier Ltd. All rights reserved.

Development of a wave-induced forcing threshold for nearshore impact of Wave Energy Converter arrays

Science.gov (United States)

O'Dea, A.; Haller, M. C.; Ozkan-Haller, H. T.

2016-02-01

Wave-induced forcing is a function of spatial gradients in the wave radiation stresses and is the main driver of alongshore currents, rip currents, and nearshore sediment transport. The installation of nearshore Wave Energy Converter (WEC) arrays may cause significant changes in the surf zone radiation stresses and could therefore impact nearshore littoral processes. In the first part of this study, a new threshold for nearshore hydrodynamic impact due to the presence of WEC devices is established based on changes in the alongshore radiation stress gradients shoreward of WEC arrays. The threshold is defined based on the relationship between nearshore radiation stresses and alongshore currents as observed in field data. Next, we perform a parametric study of the nearshore impact of WEC arrays using the SWAN wave model. Trials are conducted on an idealized, alongshore-uniform beach with a range of WEC array configurations, locations, and incident wave conditions, and conditions that generate radiation stress gradients above the impact threshold are identified. Finally, the same methodology is applied to two wave energy test sites off the coast of Newport, OR with more complicated bathymetries. Although the trends at the field sites are similar to those seen in the parametric study, the location and extent of the changes in the alongshore radiation stress gradients appear to be heavily influenced by the local bathymetry.

Myocardial infarction in Swedish subway drivers.

Science.gov (United States)

Bigert, Carolina; Klerdal, Kristina; Hammar, Niklas; Gustavsson, Per

2007-08-01

Particulate matter in urban air is associated with the risk of myocardial infarction in the general population. Very high levels of airborne particles have been detected in the subway system of Stockholm, as well as in several other large cities. This situation has caused concern for negative health effects among subway staff. The aim of this study was to investigate whether there is an increased incidence of myocardial infarction among subway drivers. Data from a population-based case-control study of men aged 40-69 in Stockholm County in 1976-1996 were used. The study included all first events of myocardial infarction in registers of hospital discharges and deaths. The controls were selected randomly from the general population. National censuses were used for information on occupation. Altogether, 22 311 cases and 131 496 controls were included. Among these, 54 cases and 250 controls had worked as subway drivers. The relative risk of myocardial infarction among subway drivers was not increased. It was 0.92 [95% confidence interval (95% CI) 0.68-1.25] when the subway drivers were compared with other manual workers and 1.06 (95% CI 0.78-1.43) when the subway drivers were compared with all other gainfully employed men. Subgroup analyses indicated no influence on the risk of myocardial infarction from the duration of employment, latency time, or time since employment stopped. Subway drivers in Stockholm do not have a higher incidence of myocardial infarction than other employed persons.

Driver's Behavior Modeling Using Fuzzy Logic

Directory of Open Access Journals (Sweden)

Sehraneh Ghaemi

2010-01-01

Full Text Available In this study, we propose a hierarchical fuzzy system for human in a driver-vehicle-environment system to model takeover by different drivers. The driver's behavior is affected by the environment. The climate, road and car conditions are included in fuzzy modeling. For obtaining fuzzy rules, experts' opinions are benefited by means of questionnaires on effects of parameters such as climate, road and car conditions on driving capabilities. Also the precision, age and driving individuality are used to model the driver's behavior. Three different positions are considered for driving and decision making. A fuzzy model called Model I is presented for modeling the change of steering angle and speed control by considering time distances with existing cars in these three positions, the information about the speed and direction of car, and the steering angle of car. Also we obtained two other models based on fuzzy rules called Model II and Model III by using Sugeno fuzzy inference. Model II and Model III have less linguistic terms than Model I for the steering angle and direction of car. The results of three models are compared for a driver who drives based on driving laws.

High frequency MOSFET gate drivers technologies and applications

CERN Document Server

Zhang, Zhiliang

2017-01-01

This book describes high frequency power MOSFET gate driver technologies, including gate drivers for GaN HEMTs, which have great potential in the next generation of switching power converters. Gate drivers serve as a critical role between control and power devices.

Fighting against a shortage of truck drivers in logistics: Measures that employers can take to promote drivers' work ability and health.

Science.gov (United States)

Staats, Ulrike; Lohaus, Daniela; Christmann, Alina; Woitschek, Michèle

2017-01-01

For several years, the transportation industry has been concerned about a severe shortage of professional truck drivers. Studies investigating the reasons found that poor working conditions and stresses and strains resulting from physiological and psychological job demands have had a negative impact on drivers' health and ability to work. Nevertheless, until now, most employers have refrained from offering measures to support the work ability and well-being of drivers, mainly due to financial pressures in the industry. The present study was aimed at designing adequate and affordable measures to support drivers' health. With reference to the Work Ability Index and the house of work ability (Ilmarinen & Tuomi, 2004), 56 truck drivers participated in guided interviews about their working conditions and health-related problems as well as their attitudes, experiences, and desires with respect to being offered supportive measures by their employers. The measures derived are specific and realizable and expected to be widely accepted by professional drivers. They are designed to elicit a positive attitude in the drivers toward exercising and to help them overcome related psychological barriers. The implementation of the recommended measures can be expected to support drivers' work ability and help reduce the frictional costs of their employers.

Science with a lunar low-frequency array: From the dark ages of the Universe to nearby exoplanets

Science.gov (United States)

Jester, Sebastian; Falcke, Heino

2009-05-01

Low-frequency radio astronomy is limited by severe ionospheric distortions below 50 MHz and complete reflection of radio waves below 10-30 MHz. Shielding of man-made interference from long-range radio broadcasts, strong natural radio emission from the Earth's aurora, and the opportunity to set up a large distributed antenna array make the lunar far side a supreme location for a low-frequency radio array. A number of new scientific drivers for such an array, such as the study of the dark ages and epoch of reionization, exoplanets, and ultra-high energy cosmic rays, have emerged and need to be studied in greater detail. Here we review the scientific potential and requirements of these new scientific drivers and discuss the constraints for various lunar surface arrays. In particular, we describe observability constraints imposed by the interstellar and interplanetary medium, calculate the achievable resolution, sensitivity, and confusion limit of a dipole array using general scaling laws, and apply them to various scientific questions. Of particular interest for a lunar array are studies of the earliest phase of the universe which are not easily accessible by other means. These are the epoch of reionization at redshifts z = 6-20, during which the very first stars and galaxies ionized most of the originally neutral intergalactic hydrogen, and the dark ages prior to that. For example, a global 21-cm wave absorption signature from primordial hydrogen in the dark ages at z = 30-50 could in principle be detected by a single dipole in an eternally dark crater on the moon, but foreground subtraction would be extremely difficult. Obtaining a high-quality power spectrum of density fluctuations in the epoch of reionization at z = 6-20, providing a wealth of cosmological data, would require about 103-105 antenna elements on the moon, which appears not unreasonable in the long term. Moreover, baryonic acoustic oscillations in the dark ages at z = 30-50 could similarly be detected

Miniaturised optical sensors for industrial applications

DEFF Research Database (Denmark)

Jakobsen, Michael Linde; Hanson, Steen Grüner

2010-01-01

. The technology is based on compact and low-cost laser sources such as Vertical Cavity Surface Emitting Lasers (VCSELs). The methods characterise the object motion by speckle translation in the near field (imaging) or far field (optical Fourier transform) by optical spatial filtering velocimetry. The volume...... of the two optical solutions is less than 1 cm3, including the application specific integrated circuit (ASIC), which processes the data and interfaces a PC/Laptop directly via a USB driver. The sensors are designed for working distances of 2 and 12 mm for near field and far field, respectively. We...

Peptic ulcer among urban bus drivers in Denmark

DEFF Research Database (Denmark)

Netterstrøm, Bo; Juel, K

1990-01-01

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 follow......-up study was also conducted. All hospital discharges with a peptic ulcer diagnosis among the bus drivers were registered from the Danish National Patient Register. All Danish men were used as reference group. On the basis of the 1978-questionnaire association between occupational and psychosocial factors...... and subsequent hospital discharge with a peptic ulcer diagnosis was studied. The prevalence of abdominal pain alleviated by food intake was 12% among bus drivers and 6% in the reference group. The incidence of hospital discharge with duodenal ulcer among younger bus drivers was twice the incidence among Danish...

Driver citation/carrier data relationship project

Science.gov (United States)

1996-09-01

The Driver/Carrier Relationship Project was commissioned to address three issues. The first was to determine if drivers of commercial motor vehicles get tickets at a different rate, depending on the carrier that they are working for. The second issue...

Driver electronic device use in 2013.

Science.gov (United States)

2015-04-01

The percentage of drivers text-messaging or visibly manipulating : hand-held devices increased from 1.5 percent in : 2012 to 1.7 percent in 2013; however, this was not a statistically : significant increase. Driver hand-held cell phone : use decrease...

Automobile Driver Fingerprinting

Directory of Open Access Journals (Sweden)

Enev Miro

2016-01-01

Full Text Available Today’s automobiles leverage powerful sensors and embedded computers to optimize efficiency, safety, and driver engagement. However the complexity of possible inferences using in-car sensor data is not well understood. While we do not know of attempts by automotive manufacturers or makers of after-market components (like insurance dongles to violate privacy, a key question we ask is: could they (or their collection and later accidental leaks of data violate a driver’s privacy? In the present study, we experimentally investigate the potential to identify individuals using sensor data snippets of their natural driving behavior. More specifically we record the in-vehicle sensor data on the controllerarea- network (CAN of a typical modern vehicle (popular 2009 sedan as each of 15 participants (a performed a series of maneuvers in an isolated parking lot, and (b drove the vehicle in traffic along a defined ~ 50 mile loop through the Seattle metropolitan area. We then split the data into training and testing sets, train an ensemble of classifiers, and evaluate identification accuracy of test data queries by looking at the highest voted candidate when considering all possible one-vs-one comparisons. Our results indicate that, at least among small sets, drivers are indeed distinguishable using only incar sensors. In particular, we find that it is possible to differentiate our 15 drivers with 100% accuracy when training with all of the available sensors using 90% of driving data from each person. Furthermore, it is possible to reach high identification rates using less than 8 minutes of training data. When more training data is available it is possible to reach very high identification using only a single sensor (e.g., the brake pedal. As an extension, we also demonstrate the feasibility of performing driver identification across multiple days of data collection

Effects of cellular telephone manipulation on driver`s performance; Jidosha untenchu no keitai denwa shiyo sosa ni kanrensuru mondai no kenkyu

Energy Technology Data Exchange (ETDEWEB)

Tokunaga, R; Ozawa, M; Hagiwara, T [Hokkaido University, Sapporo (Japan); Takagi, H; Shimojo, A [Civil Engineering Research Institute of Hokkaido, Hokkaido (Japan)

1997-10-01

The present evaluates effects of cellular telephone manipulation on driver`s performance. The major independent variables were the reaction time and the mental workload. Hart et al. proposed the concept of the subjective mental workload. Experiments were conduced using a driving simulator without motion. Findings showed that the hands free system may provide less effect than the cellular telephone on the passenger seat on driver`s reaction time and mental workload. 4 refs., 2 tabs., 5 figs.

Comparison of nonpolar III-nitride vertical-cavity surface-emitting lasers with tunnel junction and ITO intracavity contacts

KAUST Repository

Leonard, J. T.

2016-03-01

We report on the lasing of III-nitride nonpolar, violet, vertical-cavity surface-emitting lasers (VCSELs) with III-nitride tunnel-junction (TJ) intracavity contacts and ion implanted apertures (IIAs). The TJ VCSELs are compared to similar VCSELs with tin-doped indium oxide (ITO) intracavity contacts. Prior to analyzing device results, we consider the relative advantages of III-nitride TJs for blue and green emitting VCSELs. The TJs are shown to be most advantageous for violet and UV VCSELs, operating near or above the absorption edge for ITO, as they significantly reduce the total internal loss in the cavity. However, for longer wavelength III-nitride VCSELs, TJs primarily offer the advantage of improved cavity design flexibility, allowing one to make the p-side thicker using a thick n-type III-nitride TJ intracavity contact. This offers improved lateral current spreading and lower loss, compare to using ITO and p-GaN, respectively. These aspects are particularly important for achieving high-power CW VCSELs, making TJs the ideal intracavity contact for any III-nitride VCSEL. A brief overview of III-nitride TJ growth methods is also given, highlighting the molecular-beam epitaxy (MBE) technique used here. Following this overview, we compare 12 mu m aperture diameter, violet emitting, TJ and ITO VCSEL experimental results, which demonstrate the significant improvement in differential efficiency and peak power resulting from the reduced loss in the TJ design. Specifically, the TJ VCSEL shows a peak power of similar to 550 mu W with a threshold current density of similar to 3.5 kA/cm(2), while the ITO VCSELs show peak powers of similar to 80 mu W and threshold current densities of similar to 7 kA/cm

Comparison of nonpolar III-nitride vertical-cavity surface-emitting lasers with tunnel junction and ITO intracavity contacts

KAUST Repository

Leonard, J. T.; Young, E. C.; Yonkee, B. P.; Cohen, D. A.; Shen, Chao; Margalith, T.; Ng, Tien Khee; Denbaars, S. P.; Ooi, Boon S.; Speck, J. S.; Nakamura, S.

2016-01-01

We report on the lasing of III-nitride nonpolar, violet, vertical-cavity surface-emitting lasers (VCSELs) with III-nitride tunnel-junction (TJ) intracavity contacts and ion implanted apertures (IIAs). The TJ VCSELs are compared to similar VCSELs with tin-doped indium oxide (ITO) intracavity contacts. Prior to analyzing device results, we consider the relative advantages of III-nitride TJs for blue and green emitting VCSELs. The TJs are shown to be most advantageous for violet and UV VCSELs, operating near or above the absorption edge for ITO, as they significantly reduce the total internal loss in the cavity. However, for longer wavelength III-nitride VCSELs, TJs primarily offer the advantage of improved cavity design flexibility, allowing one to make the p-side thicker using a thick n-type III-nitride TJ intracavity contact. This offers improved lateral current spreading and lower loss, compare to using ITO and p-GaN, respectively. These aspects are particularly important for achieving high-power CW VCSELs, making TJs the ideal intracavity contact for any III-nitride VCSEL. A brief overview of III-nitride TJ growth methods is also given, highlighting the molecular-beam epitaxy (MBE) technique used here. Following this overview, we compare 12 mu m aperture diameter, violet emitting, TJ and ITO VCSEL experimental results, which demonstrate the significant improvement in differential efficiency and peak power resulting from the reduced loss in the TJ design. Specifically, the TJ VCSEL shows a peak power of similar to 550 mu W with a threshold current density of similar to 3.5 kA/cm(2), while the ITO VCSELs show peak powers of similar to 80 mu W and threshold current densities of similar to 7 kA/cm

Do young novice drivers overestimate their driving skills?

NARCIS (Netherlands)

Craen, S. de Twisk, D.A.M. Hagenzieker, M.P. Elffers, H. & Brookhuis, K.A.

2007-01-01

In this study the authors argue that, in order to sufficiently adapt to task demands in traffic, drivers have to make an assessment of their own driving skills. There are indications that drivers in general, and novice drivers in particular, overestimate their driving skills. The objective of this

Modeling driver stop/run behavior at the onset of a yellow indication considering driver run tendency and roadway surface conditions.

Science.gov (United States)

Elhenawy, Mohammed; Jahangiri, Arash; Rakha, Hesham A; El-Shawarby, Ihab

2015-10-01

The ability to model driver stop/run behavior at signalized intersections considering the roadway surface condition is critical in the design of advanced driver assistance systems. Such systems can reduce intersection crashes and fatalities by predicting driver stop/run behavior. The research presented in this paper uses data collected from two controlled field experiments on the Smart Road at the Virginia Tech Transportation Institute (VTTI) to model driver stop/run behavior at the onset of a yellow indication for different roadway surface conditions. The paper offers two contributions. First, it introduces a new predictor related to driver aggressiveness and demonstrates that this measure enhances the modeling of driver stop/run behavior. Second, it applies well-known artificial intelligence techniques including: adaptive boosting (AdaBoost), random forest, and support vector machine (SVM) algorithms as well as traditional logistic regression techniques on the data in order to develop a model that can be used by traffic signal controllers to predict driver stop/run decisions in a connected vehicle environment. The research demonstrates that by adding the proposed driver aggressiveness predictor to the model, there is a statistically significant increase in the model accuracy. Moreover the false alarm rate is significantly reduced but this reduction is not statistically significant. The study demonstrates that, for the subject data, the SVM machine learning algorithm performs the best in terms of optimum classification accuracy and false positive rates. However, the SVM model produces the best performance in terms of the classification accuracy only. Copyright © 2015 Elsevier Ltd. All rights reserved.

Determinants and Drivers of Infectious Disease Threat Events in Europe.

Science.gov (United States)

Semenza, Jan C; Lindgren, Elisabet; Balkanyi, Laszlo; Espinosa, Laura; Almqvist, My S; Penttinen, Pasi; Rocklöv, Joacim

2016-04-01

Infectious disease threat events (IDTEs) are increasing in frequency worldwide. We analyzed underlying drivers of 116 IDTEs detected in Europe during 2008-2013 by epidemic intelligence at the European Centre of Disease Prevention and Control. Seventeen drivers were identified and categorized into 3 groups: globalization and environment, sociodemographic, and public health systems. A combination of >2 drivers was responsible for most IDTEs. The driver category globalization and environment contributed to 61% of individual IDTEs, and the top 5 individual drivers of all IDTEs were travel and tourism, food and water quality, natural environment, global trade, and climate. Hierarchical cluster analysis of all drivers identified travel and tourism as a distinctly separate driver. Monitoring and modeling such disease drivers can help anticipate future IDTEs and strengthen control measures. More important, intervening directly on these underlying drivers can diminish the likelihood of the occurrence of an IDTE and reduce the associated human and economic costs.

The driver, the road, the rules … and the rest? A systems-based approach to young driver road safety.

Science.gov (United States)

Scott-Parker, B; Goode, N; Salmon, P

2015-01-01

The persistent overrepresentation of young drivers in road crashes is universally recognised. A multitude of factors influencing their behaviour and safety have been identified through methods including crash analyses, simulated and naturalistic driving studies, and self-report measures. Across the globe numerous, diverse, countermeasures have been implemented; the design of the vast majority of these has been informed by a driver-centric approach. An alternative approach gaining popularity in transport safety is the systems approach which considers not only the characteristics of the individual, but also the decisions and actions of other actors within the road transport system, along with the interactions amongst them. This paper argues that for substantial improvements to be made in young driver road safety, what has been learnt from driver-centric research needs to be integrated into a systems approach, thus providing a holistic appraisal of the young driver road safety problem. Only then will more effective opportunities and avenues for intervention be realised. Copyright © 2014 Elsevier Ltd. All rights reserved.

Investigation of switch designs for the dynamic load current multiplier scheme on the SPHYNX microsecond linear transformer driver

International Nuclear Information System (INIS)

Maysonnave, T.; Bayol, F.; Demol, G.; Almeida, T. d'; Lassalle, F.; Morell, A.; Grunenwald, J.; Chuvatin, A.S.; Pecastaing, L.; De Ferron, A.S.

2014-01-01

SPHINX is a microsecond linear transformer driver LTD, used essentially for implosion of Z-pinch loads in direct drive mode. It can deliver a 6-MA current pulse within 800 ns into a Z-pinch load. The dynamic load current multiplier concept enables the current pulse to be modified by increasing its amplitude while reducing its rise time before being delivered to the load. This compact system is made up of concentric electrodes (auto transformer), a dynamic flux extruder (cylindrical wire array), a vacuum convolute (eight post-holes), and a vacuum closing switch, which is the key component of the system. Several different schemes are investigated for designing a vacuum switch suitable for operating the dynamic load current multiplier on the SPHINX generator for various applications, including isentropic compression experiments and Z-pinch radiation effects studies. In particular, the design of a compact vacuum surface switch and a multichannel vacuum switch, located upstream of the load are studied. Electrostatic simulations supporting the switch designs are presented along with test bed experiments. Initial results from shots on the SPHINX driver are also presented. (authors)

Solar Array Power Conditioning for a Spinning Satellite

Science.gov (United States)

De Luca, Antonio; Chirulli, Giovanni

2008-09-01

The conditioning of the output power from a solar array can mainly be achieved by the adoption of DET or MPPT based architecture. There are several factors that can orientate the choice of the system designer towards one solution or the other; some of them maybe inherent to the mission derived requirements (Illumination levels, EMC cleanliness, etc.), others come directly from a careful assessment of performances and losses of both power conditioner and solar array.Definition of the criteria on which basis the final choice is justified is important as they have to guarantee a clear determination of the available versus the required power in all those mission conditions identifiable as design drivers for the overall satellite system both in terms of mass and costs.Such criteria cannot just be simple theoretical enunciations of principles; nor the meticulous definition of them on a case by case basis for different types of missions as neither option gives a guarantee of being conclusive.The aim of this paper is then to suggest assessment steps and guidelines that can be considered generically valid for any mission case, starting from the exposition of the trade off activity performed in order to choose the power conditioning solution for a spinning satellite having unregulated power bus architecture. Calculations and numerical simulations have been made in order to establish the needed solar array surface in case of adoption of a DET or MPPT solution, taking into account temperature and illumination levels on the solar cells, as well as power losses and inefficiencies from the solar generator to the main power bus, in different mission phases. Particular attention has been taken in order to correctly evaluate the thermal effects on the rest of the spacecraft as function of the adopted power system regulation.

Licensing and Other Controls of the Drinking Driver.

Science.gov (United States)

Waller, Patricia F.

Driver licensing, the only state program with the opportunity for routine personal contact with every driver, has unmatched potential for both general and specific countermeasures to the problem of drunk driving. General countermeasures apply to large groups of drivers prior to the occurrence of any infraction. They may be considered basically…

Functional Bus Driver-Pupil Passenger Relationships.

Science.gov (United States)

Farmer, Ernest

1987-01-01

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

Challenges for Older Drivers in Urban, Suburban, and Rural Settings

Directory of Open Access Journals (Sweden)

Rashmi P. Payyanadan

2018-03-01

Full Text Available Along with age-related factors, geographical settings—urban, suburban, and rural areas—also contribute to the differences in fatal crashes among older drivers. These differences in crash outcomes might be attributed to the various driving challenges faced by older drivers residing in different locations. To understand these challenges from the perspective of the older driver, a focus group study was conducted with drivers 65 and older from urban, suburban, and rural settings. Guided-group interviews were used to assess driving challenges, mobility options, opportunities for driver support systems (DSS, and alternate transportation needs. Content analysis of the interview responses resulted in four categories representing common challenges faced by older drivers across the settings: behavior of other drivers on the road, placement of road signs, reduced visibility of road signs due to age-related decline, and difficulties using in-vehicle technologies. Six categories involved location-specific challenges such as heavy traffic situations for urban and suburban drivers, and multi-destination trips for rural drivers. Countermeasures implemented by older drivers to address these challenges primarily involved route selection and avoidance. Technological advances of DSS systems provide a unique opportunity to support the information needs for route selection and avoidance preferences of drivers. Using the content analysis results, a framework was built to determine additional and modified DSS features to meet the specific challenges of older drivers in urban, suburban, and rural settings. These findings suggest that there is heterogeneity in the driving challenges and preferences of older drivers based on their location. Consequently, DSS technologies and vehicle automation need to be tailored to not only meet the driving safety and mobility needs of older drivers as a population, but also to their driving environment.

How to identify the key factors that affect driver perception of accident risk. A comparison between Italian and Spanish driver behavior.

Science.gov (United States)

de Oña, Juan; de Oña, Rocio; Eboli, Laura; Forciniti, Carmen; Mazzulla, Gabriella

2014-12-01

Road crashes can be caused by different factors, including infrastructure, vehicles, and human variables. Many research studies have focused solely on identifying the key factors that cause road crashes. From these studies, it emerged that human factors have the most relevant impact on accident severity. More specifically, accident severity depends on several factors related directly to the driver, i.e., driving experience, driver's socio-economic characteristics, and driving behavior and attitudes. In this paper, we investigate driver behaviors and attitudes while driving and specifically focus on different methods for identifying the factors that most affect the driver's perception of accident risk. To this end, we designed and conducted a survey in two different European contexts: the city of Cosenza, which is located in the south of Italy, and the city of Granada, which is located in the south of Spain. Samples of drivers were contacted for their opinions on certain aspects of driving rules and attitudes while driving, and different types of questions were addressed to the drivers to assess their judgments of these aspects. Consequently, different methods of data analysis were applied to determine the aspects that heavily influence driver perception of accident risk. An experiment based on the stated preferences (SP) was carried out with the drivers, and the SP data were analyzed using an ordered probit (OP) model. Interesting findings emerged from different analyses of the data and from the comparisons among the data collected in the two different territorial contexts. We found that both Italian and Spanish drivers consider driving in an altered psychophysical state and violating the overtaking rules to be the most risky behaviors. Copyright © 2014 Elsevier Ltd. All rights reserved.

Development of a Two-Dimensional Array of Individually Addressable Micro-Mirrors for NGST Application

Science.gov (United States)

Dutta, S. B.; Mott, D. B.; Allen, C. A.; Ewin, A. J.; Jhabvala, M. D.; Kotecki, C. A.; Kuhn, J. L.; MacKenty, J. W.

2000-05-01

NASA's missions of the 21st century will use small, low cost, efficient instruments for Earth and Space Science studies. Development of technologies that accommodate these requirements is essential for space applications. Micro Electro Mechanical Systems (MEMS) technology development for sensors and actuators plays a major role in this effort. We are developing a two dimensional array of individually addressable, cryogenic micro-mirrors, a MEMS based component, specifically for application in the Multi Object Spectrometer (MOS) in NGST. Two-dimensional, individually addressable and tiltable aluminum micro-mirror-arrays (MMA) have been developed and prototype arrays of different sizes have been fabricated in the Detector Development Laboratory of NASA, GSFC. Each micro-mirror of the array has 100micronx100micron pixel size and is capable of tilting +/- 10 degrees by electrostatic actuation. We have completed extensive analytical studies and performed laboratory tests to compare model predictions with actual performance of a 3x3 array. The mirrors have been tested to operate at cryogenic temperature. Recently we have completed the integration of a CMOS based address and driver circuit for the MMA with its mechanical structure. Our goal is to extend the development to a 1024x1024 array, primarily for NGST and also for other imaging and spectroscopy applications. For NGST MOS, MMAs will be used as a reflective slit-mask at a focal plane of the spectrometer providing a large field of view together with diffraction limited angular resolution for a grating spectrometer. Selected areas of the mirror-array will be tilted to select portions of the scene so that observation of up to 1000 simultaneous spectra of sparse targets will be possible. This provides a factor of 100 improvement in observing speed over conventional spectrometers. Details of the technology development along with its application to NGST will be discussed. This work is supported by the GSFC Director

Discriminating Drivers through Human Factor and Behavioral Difference

Directory of Open Access Journals (Sweden)

Ju Seok Oh

2011-05-01

Full Text Available Since Greenwood and Woods' (1919 study in tendency of accident, many researchers have insisted that various human factors (sensation seeking, anger, anxiety are highly correlated with reckless driving and traffic accidents. Oh and Lee (2011 designed the Driving Behavior Determinants Questionnaire, a psychological tool to predict danger level of drivers and discriminate them into three groups (normal, unintentionally reckless, and intentionally reckless by their characteristics, attitude, and expected reckless behavior level. This tool's overall accuracy of discrimination was 70%. This study aimed to prove that the discrimination reflects the behavioral difference of drivers. Twenty-four young drivers were requested to react to the visual stimuli (tests for subjective speed sense, simple visual reaction time, and left turning at own risk. The results showed no differences in subjective speed sense among the driver groups, which means drivers' excessive speeding behaviors occur due to intention based on personality and attitude, not because of sensory disorders. In addition, there were no differences in simple reaction time among driver groups. However, the results of the ‘Left turning at drivers’ own risk task” revealed significant group differences. All reckless drivers showed a greater degree of dangerous left turning behaviors than the normal group did.

High-Voltage LED Light Engine with Integrated Driver

Energy Technology Data Exchange (ETDEWEB)

Soer, Wouter [Lumileds LLC, San Jose, CA (United States)

2016-02-29

LED luminaires have seen dramatic changes in cost breakdown over the past few years. The LED component cost, which until recently was the dominant portion of luminaire cost, has fallen to a level of the same order as the other luminaire components, such as the driver, housing, optics etc. With the current state of the technology, further luminaire performance improvement and cost reduction is realized most effectively by optimization of the whole system, rather than a single component. This project focuses on improving the integration between LEDs and drivers. Lumileds has developed a light engine platform based on low-cost high-power LEDs and driver topologies optimized for integration with these LEDs on a single substrate. The integration of driver and LEDs enables an estimated luminaire cost reduction of about 25% for targeted applications, mostly due to significant reductions in driver and housing cost. The high-power LEDs are based on Lumileds’ patterned sapphire substrate flip-chip (PSS-FC) technology, affording reduced die fabrication and packaging cost compared to existing technology. Two general versions of PSS-FC die were developed in order to create the desired voltage and flux increments for driver integration: (i) small single-junction die (0.5 mm²), optimal for distributed lighting applications, and (ii) larger multi-junction die (2 mm² and 4 mm²) for high-power directional applications. Two driver topologies were developed: a tapped linear driver topology and a single-stage switch-mode topology, taking advantage of the flexible voltage configurations of the new PSS-FC die and the simplification opportunities enabled by integration of LEDs and driver on the same board. A prototype light engine was developed for an outdoor “core module” application based on the multi-junction PSS-FC die and the single-stage switch-mode driver. The light engine meets the project efficacy target of 128 lm/W at a luminous flux

A learning-based autonomous driver: emulate human driver's intelligence in low-speed car following

Science.gov (United States)

Wei, Junqing; Dolan, John M.; Litkouhi, Bakhtiar

2010-04-01

In this paper, an offline learning mechanism based on the genetic algorithm is proposed for autonomous vehicles to emulate human driver behaviors. The autonomous driving ability is implemented based on a Prediction- and Cost function-Based algorithm (PCB). PCB is designed to emulate a human driver's decision process, which is modeled as traffic scenario prediction and evaluation. This paper focuses on using a learning algorithm to optimize PCB with very limited training data, so that PCB can have the ability to predict and evaluate traffic scenarios similarly to human drivers. 80 seconds of human driving data was collected in low-speed (car-following scenarios. In the low-speed car-following tests, PCB was able to perform more human-like carfollowing after learning. A more general 120 kilometer-long simulation showed that PCB performs robustly even in scenarios that are not part of the training set.

[Health reasons for work disability among municipal transport drivers].

Science.gov (United States)

Szubert, Zuzanna; Sobala, Wojciech

2005-01-01

The health condition of public transport drivers is one of the factors playing a role in assuring safety of passengers taking use of this kind of transportation means. Therefore, the assessment of pathologies occurring in this occupational group is essential from the prevention point of view. Drivers employed in the municipal transport system are at particular risk. The aim of the study was to define health reasons of work disability among bus and tram drivers in general and to indicate pathologies responsible for disabilities in particular. The study covered 940 drivers (including 788 men and 152 women) employed in a municipal transportation enterprise during the years 1996-2000. Bus (30%) and tram (22%) drivers as well as transport service workers (48%), aged over 45 years, but under the retirement age, were eligible for the study. The analysis of temporary work disability during a five-year period was based on sickness absence, sickness absence rate and the average duration of sickness absence. The analysis revealed that diseases of the circulatory system form the major group of pathologies responsible for total sickness absence among bus drivers (43%), tram drivers (27%) and transport service workers (27%). These disease are also a leading cause of earlier retirement. They mostly include ischemic heart disease in bus drivers and hypertension in tram drivers. Cancers (pleura, kidney and eye) were responsible for 9% of sickness absence in the group of male tram drivers, whereas endocrine, nutritional and metabolic diseases and immunity disorders (diabetes, disorders of thyroid gland) in 16% of female tram drivers. Diseases of the musculoskeletal system were major causes of sickness absence among female tram drivers (24%), whereas malignant and benign neoplasms of breast and uterine myoma in 24% of female transport service workers. The results of the analysis are in agreement with the literature findings and provide explicit evidence that employment in the

A COOPERATIVE ASSISTANCE SYSTEM BETWEEN VEHICLES FOR ELDERLY DRIVERS

Directory of Open Access Journals (Sweden)

Naohisa HASHIMOTO

2009-01-01

Full Text Available This paper proposes a new concept of elderly driver assistance systems, which performs the assistance by cooperative driving between two vehicles, and describes some experiments with elderly drivers. The assistance consists of one vehicle driven by an elderly driver called a guest vehicle and the other driven by a assisting driver called a host vehicle, and the host vehicle assists or escorts the guest vehicle through the inter-vehicle communications. The functions of the systems installed on a single-seat electric vehicle are highly evaluated by subjects of elderly drivers in virtual streets on a test track.

A driver-adaptive stability control strategy for sport utility vehicles

Science.gov (United States)

Zhu, Shenjin; He, Yuping

2017-08-01

Conventional vehicle stability control (VSC) systems are designed for average drivers. For a driver with a good driving skill, the VSC systems may be redundant; for a driver with a poor driving skill, the VSC intervention may be inadequate. To increase safety of sport utility vehicles (SUVs), this paper proposes a novel driver-adaptive VSC (DAVSC) strategy based on scaling the target yaw rate commanded by the driver. The DAVSC system is adaptive to drivers' driving skills. More control effort would be exerted for drivers with poor driving skills, and vice versa. A sliding mode control (SMC)-based differential braking (DB) controller is designed using a three degrees of freedom (DOF) yaw-plane model. An eight DOF nonlinear yaw-roll model is used to simulate the SUV dynamics. Two driver models, namely longitudinal and lateral, are used to 'drive' the virtual SUV. By integrating the virtual SUV, the DB controller, and the driver models, the performance of the DAVSC system is investigated. The simulations demonstrate the effectiveness of the DAVSC strategy.

Real-time driver fatigue detection based on face alignment

Science.gov (United States)

Tao, Huanhuan; Zhang, Guiying; Zhao, Yong; Zhou, Yi

2017-07-01

The performance and robustness of fatigue detection largely decrease if the driver with glasses. To address this issue, this paper proposes a practical driver fatigue detection method based on face alignment at 3000 FPS algorithm. Firstly, the eye regions of the driver are localized by exploiting 6 landmarks surrounding each eye. Secondly, the HOG features of the extracted eye regions are calculated and put into SVM classifier to recognize the eye state. Finally, the value of PERCLOS is calculated to determine whether the driver is drowsy or not. An alarm will be generated if the eye is closed for a specified period of time. The accuracy and real-time on testing videos with different drivers demonstrate that the proposed algorithm is robust and obtain better accuracy for driver fatigue detection compared with some previous method.

Railway suicide: the psychological effects on drivers.

Science.gov (United States)

Farmer, R; Tranah, T; O'Donnell, I; Catalan, J

1992-05-01

People have jumped (or fallen) in front of trains on the London Underground system in increasing numbers throughout the twentieth century. During the past decade there have been about 100 such incidents each year, of which around 90 would involve the train driver witnessing his train strike the person on the track. Most are suicides or attempts at suicide. They represent major unexpected and violent events in the lives of the train drivers and it might be expected that some of them would respond by developing a post-traumatic stress reaction of the type identified by Horowitz (1976) or other adverse psychological reactions or both. The research reported in this paper was designed to characterize the range of responses of drivers to the experiences of killing or injuring members of the public during the course of their daily work. It was found that 16.3% of the drivers involved in incidents did develop post-traumatic stress disorder and that other diagnoses, e.g. depression and phobic states, were present in 39.5% of drivers when interviewed one month after the incident.

Cross-cultural differences in drivers' speed choice.

Science.gov (United States)

Wallén Warner, Henriette; Ozkan, Türker; Lajunen, Timo

2009-07-01

The aim of the present study was to examine if there are any cross-cultural differences between Swedish and Turkish drivers' rating of the variables in the theory of planned behaviour (TPB) with regard to complying with the speed limit. A sample of 219 Swedish and 252 Turkish drivers completed a questionnaire including questions based on the theory of planned behaviour (i.e. regarding attitude, subjective norm, perceived behavioural control, intention and behaviour). The results show that country differences in drivers' intention to comply with the speed limit as well as their self-reported compliance could be explained by differences found in their attitude, subjective norm and perceived behavioural control. Furthermore, drivers who live in a country with fewer road traffic fatalities (i.e. Sweden), compared with drivers who live in a country with more road traffic fatalities (i.e. Turkey), reported a more positive attitude towards complying with the speed limit, a more positive subjective norm, a higher perceived behavioural control, a higher intention and a larger proportion of the time spent complying.

Views of US drivers about driving safety.

Science.gov (United States)

Williams, Allan F

2003-01-01

To assess how drivers view dangers on the highway, what motivates them to drive safely, how they say they reduce their crash and injury risk, and how they rate their own driving skills. Most drivers rated their skills as better than average. The biggest motivating factor for safe driving was concern for safety of others in their vehicle, followed by negative outcomes such as being in a crash, increased insurance costs, and fines. The greatest threats to their safety were thought to be other drivers' actions that increase crash risk such as alcohol impairment or running red lights. In terms of reducing crashes and injuries, drivers tended to focus on actions they could take such as driving defensively or using seat belts. There was less recognition of the role of vehicles and vehicle features in crash or injury prevention. Knowing how drivers view themselves and others, their concerns, and their motivations and techniques for staying out of trouble on the roads provides insight into the difficulty of changing driving practices.

Design of area array CCD image acquisition and display system based on FPGA

Science.gov (United States)

Li, Lei; Zhang, Ning; Li, Tianting; Pan, Yue; Dai, Yuming

2014-09-01

With the development of science and technology, CCD(Charge-coupled Device) has been widely applied in various fields and plays an important role in the modern sensing system, therefore researching a real-time image acquisition and display plan based on CCD device has great significance. This paper introduces an image data acquisition and display system of area array CCD based on FPGA. Several key technical challenges and problems of the system have also been analyzed and followed solutions put forward .The FPGA works as the core processing unit in the system that controls the integral time sequence .The ICX285AL area array CCD image sensor produced by SONY Corporation has been used in the system. The FPGA works to complete the driver of the area array CCD, then analog front end (AFE) processes the signal of the CCD image, including amplification, filtering, noise elimination, CDS correlation double sampling, etc. AD9945 produced by ADI Corporation to convert analog signal to digital signal. Developed Camera Link high-speed data transmission circuit, and completed the PC-end software design of the image acquisition, and realized the real-time display of images. The result through practical testing indicates that the system in the image acquisition and control is stable and reliable, and the indicators meet the actual project requirements.

Impact Driver With Integral Sliding Hammer

Science.gov (United States)

Wallace, Bilby J.

1987-01-01

Tool combines impact driver with sliding dead-blow hammer. Used for any purpose for which ordinary impact driver used; tightening fasteners or driving starter holes for drill. Tool protects user from accidental injury and surrounding equipment from damage that might occur from ordinary arm-wielded hammer. Especially useful in underwater work.

X3 expansion tube driver gas spectroscopy and temperature measurements

Science.gov (United States)

Parekh, V.; Gildfind, D.; Lewis, S.; James, C.

2018-07-01

The University of Queensland's X3 facility is a large, free-piston driven expansion tube used for super-orbital and high Mach number scramjet aerothermodynamic studies. During recent development of new scramjet test flow conditions, experimentally measured shock speeds were found to be significantly lower than that predicted by initial driver performance calculations. These calculations were based on ideal, isentropic compression of the driver gas and indicated that loss mechanisms, not accounted for in the preliminary analysis, were significant. The critical determinant of shock speed is peak driver gas sound speed, which for a given gas composition depends on the peak driver gas temperature. This temperature may be inaccurately estimated if an incorrect fill temperature is assumed, or if heat losses during driver gas compression are significant but not accounted for. For this study, the ideal predicted peak temperature was 3750 K, without accounting for losses. However, a much lower driver temperature of 2400 K is suggested based on measured experimental shock speeds. This study aimed to measure initial and peak driver gas temperatures for a representative X3 operating condition. Examination of the transient temperatures of the driver gas and compression tube steel wall during the initial fill process showed that once the filling process was complete, the steady-state driver gas temperature closely matched the tube wall temperature. Therefore, while assuming the gas is initially at the ambient laboratory temperature is not a significant source of error, it can be entirely mitigated by simply monitoring tube wall temperature. Optical emission spectroscopy was used to determine the driver gas spectra after diaphragm rupture; the driver gas emission spectrum exhibited a significant continuum radiation component, with prominent spectral lines attributed to contamination of the gas. A graybody approximation of the continuum suggested a peak driver gas temperature of

X3 expansion tube driver gas spectroscopy and temperature measurements

Science.gov (United States)

Parekh, V.; Gildfind, D.; Lewis, S.; James, C.

2017-11-01

The University of Queensland's X3 facility is a large, free-piston driven expansion tube used for super-orbital and high Mach number scramjet aerothermodynamic studies. During recent development of new scramjet test flow conditions, experimentally measured shock speeds were found to be significantly lower than that predicted by initial driver performance calculations. These calculations were based on ideal, isentropic compression of the driver gas and indicated that loss mechanisms, not accounted for in the preliminary analysis, were significant. The critical determinant of shock speed is peak driver gas sound speed, which for a given gas composition depends on the peak driver gas temperature. This temperature may be inaccurately estimated if an incorrect fill temperature is assumed, or if heat losses during driver gas compression are significant but not accounted for. For this study, the ideal predicted peak temperature was 3750 K, without accounting for losses. However, a much lower driver temperature of 2400 K is suggested based on measured experimental shock speeds. This study aimed to measure initial and peak driver gas temperatures for a representative X3 operating condition. Examination of the transient temperatures of the driver gas and compression tube steel wall during the initial fill process showed that once the filling process was complete, the steady-state driver gas temperature closely matched the tube wall temperature. Therefore, while assuming the gas is initially at the ambient laboratory temperature is not a significant source of error, it can be entirely mitigated by simply monitoring tube wall temperature. Optical emission spectroscopy was used to determine the driver gas spectra after diaphragm rupture; the driver gas emission spectrum exhibited a significant continuum radiation component, with prominent spectral lines attributed to contamination of the gas. A graybody approximation of the continuum suggested a peak driver gas temperature of

SNP Arrays

Directory of Open Access Journals (Sweden)

Jari Louhelainen

2016-10-01

Full Text Available The papers published in this Special Issue “SNP arrays” (Single Nucleotide Polymorphism Arrays focus on several perspectives associated with arrays of this type. The range of papers vary from a case report to reviews, thereby targeting wider audiences working in this field. The research focus of SNP arrays is often human cancers but this Issue expands that focus to include areas such as rare conditions, animal breeding and bioinformatics tools. Given the limited scope, the spectrum of papers is nothing short of remarkable and even from a technical point of view these papers will contribute to the field at a general level. Three of the papers published in this Special Issue focus on the use of various SNP array approaches in the analysis of three different cancer types. Two of the papers concentrate on two very different rare conditions, applying the SNP arrays slightly differently. Finally, two other papers evaluate the use of the SNP arrays in the context of genetic analysis of livestock. The findings reported in these papers help to close gaps in the current literature and also to give guidelines for future applications of SNP arrays.

Understanding Factors of Distraction among Intrastate Bus Driver

Directory of Open Access Journals (Sweden)

Yunos Muhammad Nur Annuar Mohd

2017-01-01

Full Text Available The increase in number of the world population have affected the demand for public transport especially in larger cities. Intrastate buses are chosen as the main public transport by many people due to its affordable fares. Therefore, a better performance of the intrastate bus drivers would be significant to cater the high demand. Nevertheless, distraction among the intrastate bus drivers have been found as one of the major factors that could affect the performance of the drivers. Therefore, the objective of this paper is to provide a better understanding on the factors of distraction among intrastate bus drivers. This paper refers to findings from previous researches which are related to this field of study. In conclusion, this paper will provide a list of factors of distraction among the intrastate bus drivers which may degrade their performance.

Development of pulsed high current drivers for fast Z-pinch

International Nuclear Information System (INIS)

Sun Fengju; Qiu Aici; Zeng Zhengzhong; Zeng Jiangtao; Kuai Bin; Yang Hailiang

2006-01-01

It is required that the peak current of high power pulsed drive for fast Z-pinch reaches 60 MA to realize inertial confine fusion (ICF) and high yield (HY). With the conventional technological methods similar to the Z or Saturn apparatus, increasing driver current further is impractical and difficult according to the cost, structure complexity and reliability of the driver, so it is necessary to develop novel fast pulsed high current driver. The present art-of-state and trends of fast Z-pinch driver are summarized, and the typical conceptual designs and technological methods on ICF/HY PRS (plasma radiation source) and destroying-level super X-ray simulators in USA and Russia are outlined, such as HCEI's UGXX1 driver and new Saturn driver based on fast linear transformer driver (FLTD) and novel driver based on fast Marx generator (FMG) with current of 15 MA. The crucial technological problems and requirements to investigate in the future are presented. (authors)

Does early training improve driving skills of young novice French drivers?

Science.gov (United States)

Freydier, Chloé; Berthelon, Catherine; Bastien-Toniazzo, Mireille

2016-11-01

The aim of this research was to study drivers' performances and divided attention depending on their initial training. The performances of young novice drivers who received early training, traditionally trained drivers and more experienced drivers were compared during a dual task consisting of a simulated car-following task and a number' parity judgment task. It was expected that, due to their limited driving experience, the young novice drivers would have more difficulty in adequately distributing their attention between the two tasks. Poorer performances by novice drivers than experienced drivers were therefore expected. The results indicate that traditionally trained drivers had more difficulties in speed regulation and maintaining their position in the lane than drivers with early training and experienced drivers. Performance impairment linked to driving inexperience was also found in the secondary task. The results were interpreted regarding the attentional resources involved in driving with a secondary task and supported the positive effects of French early training. Copyright © 2016 Elsevier Ltd. All rights reserved.

Estimating likelihood of future crashes for crash-prone drivers

Directory of Open Access Journals (Sweden)

Subasish Das

2015-06-01

Full Text Available At-fault crash-prone drivers are usually considered as the high risk group for possible future incidents or crashes. In Louisiana, 34% of crashes are repeatedly committed by the at-fault crash-prone drivers who represent only 5% of the total licensed drivers in the state. This research has conducted an exploratory data analysis based on the driver faultiness and proneness. The objective of this study is to develop a crash prediction model to estimate the likelihood of future crashes for the at-fault drivers. The logistic regression method is used by employing eight years' traffic crash data (2004–2011 in Louisiana. Crash predictors such as the driver's crash involvement, crash and road characteristics, human factors, collision type, and environmental factors are considered in the model. The at-fault and not-at-fault status of the crashes are used as the response variable. The developed model has identified a few important variables, and is used to correctly classify at-fault crashes up to 62.40% with a specificity of 77.25%. This model can identify as many as 62.40% of the crash incidence of at-fault drivers in the upcoming year. Traffic agencies can use the model for monitoring the performance of an at-fault crash-prone drivers and making roadway improvements meant to reduce crash proneness. From the findings, it is recommended that crash-prone drivers should be targeted for special safety programs regularly through education and regulations.

Car drivers' perceptions of electronic stability control (ESC) systems.

Science.gov (United States)

Vadeby, Anna; Wiklund, Mats; Forward, Sonja

2011-05-01

As a way to reduce the number of car crashes different in-car safety devices are being introduced. In this paper one such application is being investigated, namely the electronic stability control system (ESC). The study used a survey method, including 2000 private car drivers (1000 driving a car with ESC and 1000 driving a car without ESC). The main objective was to investigate the effect of ESC on driver behaviour. Results show that drivers report that they drive even more carelessly when they believe that they have ESC, than when they do not. Men are more risk prone than women and young drivers more than older drivers. Using the theory of planned behaviour the results show that attitude, subjective norm and perceived control explain between 62% and 67% of driver's variation of intentions to take risks. When descriptive norm was added to the model a small but statistically significant increase was found. The study also shows that more than 35% erroneously believe that their car is equipped with an ESC system. These findings may suggest that driver behaviour could reduce the positive effect ESC has on accidents. It also shows that drivers who purchase a new car are not well informed about what kind of safety devices the car is equipped with. These findings highlight the need for more targeted information to drivers. Copyright © 2010 Elsevier Ltd. All rights reserved.

How driving duration influences drivers' visual behaviors and fatigue ...

African Journals Online (AJOL)

unhcc

Eye fixations express the focus of driver's visual attention on driving, ... driver's attention is attracted by fatigue. The second ... was divided into seven refined categories (see Table 1), ...... driver fatigue in terms of line crossing: a pilot study.

Discovery of cancer common and specific driver gene sets

Science.gov (United States)

2017-01-01

Abstract Cancer is known as a disease mainly caused by gene alterations. Discovery of mutated driver pathways or gene sets is becoming an important step to understand molecular mechanisms of carcinogenesis. However, systematically investigating commonalities and specificities of driver gene sets among multiple cancer types is still a great challenge, but this investigation will undoubtedly benefit deciphering cancers and will be helpful for personalized therapy and precision medicine in cancer treatment. In this study, we propose two optimization models to de novo discover common driver gene sets among multiple cancer types (ComMDP) and specific driver gene sets of one certain or multiple cancer types to other cancers (SpeMDP), respectively. We first apply ComMDP and SpeMDP to simulated data to validate their efficiency. Then, we further apply these methods to 12 cancer types from The Cancer Genome Atlas (TCGA) and obtain several biologically meaningful driver pathways. As examples, we construct a common cancer pathway model for BRCA and OV, infer a complex driver pathway model for BRCA carcinogenesis based on common driver gene sets of BRCA with eight cancer types, and investigate specific driver pathways of the liquid cancer lymphoblastic acute myeloid leukemia (LAML) versus other solid cancer types. In these processes more candidate cancer genes are also found. PMID:28168295

Lane-changing model with dynamic consideration of driver's propensity

Science.gov (United States)

Wang, Xiaoyuan; Wang, Jianqiang; Zhang, Jinglei; Ban, Xuegang Jeff

2015-07-01

Lane-changing is the driver's selection result of the satisfaction degree in different lane driving conditions. There are many different factors influencing lane-changing behavior, such as diversity, randomicity and difficulty of measurement. So it is hard to accurately reflect the uncertainty of drivers' lane-changing behavior. As a result, the research of lane-changing models is behind that of car-following models. Driver's propensity is her/his emotion state or the corresponding preference of a decision or action toward the real objective traffic situations under the influence of various dynamic factors. It represents the psychological characteristics of the driver in the process of vehicle operation and movement. It is an important factor to influence lane-changing. In this paper, dynamic recognition of driver's propensity is considered during simulation based on its time-varying discipline and the analysis of the driver's psycho-physic characteristics. The Analytic Hierarchy Process (AHP) method is used to quantify the hierarchy of driver's dynamic lane-changing decision-making process, especially the influence of the propensity. The model is validated using real data. Test results show that the developed lane-changing model with the dynamic consideration of a driver's time-varying propensity and the AHP method are feasible and with improved accuracy.

Optimizing the Universal Robots ROS driver

DEFF Research Database (Denmark)

Andersen, Thomas Timm

improvement both in terms of faster reaction as well as making it possible to control the robot using either ros_control or ordinary joint speed commands, which is required for many types of sensory based control like visual servoing. The developed driver is compared to the drivers already existing in the ROS...

A novel method to design sparse linear arrays for ultrasonic phased array.

Science.gov (United States)

Yang, Ping; Chen, Bin; Shi, Ke-Ren

2006-12-22

In ultrasonic phased array testing, a sparse array can increase the resolution by enlarging the aperture without adding system complexity. Designing a sparse array involves choosing the best or a better configuration from a large number of candidate arrays. We firstly designed sparse arrays by using a genetic algorithm, but found that the arrays have poor performance and poor consistency. So, a method based on the Minimum Redundancy Linear Array was then adopted. Some elements are determined by the minimum-redundancy array firstly in order to ensure spatial resolution and then a genetic algorithm is used to optimize the remaining elements. Sparse arrays designed by this method have much better performance and consistency compared to the arrays designed only by a genetic algorithm. Both simulation and experiment confirm the effectiveness.

Dynamic Characteristics of DC Servo Motor Driven by Conventional Servo Driver: Estimation of Circuit Constants in Conventional Servo Driver

OpenAIRE

酒井, 史敏; 神谷, 好承; 関, 啓明; 疋津, 正利

2000-01-01

DC servo motors that are made as manufactured goods in the factory are widely used as actuators for driving many automatic machines. Then the manufactured driver (amplifier) that is matched to its servo motor is coveniently chosen to drive when aiming at high performance of the motion control. Motion of motor that is driven by the manufactured servo driver has very complicated dynamic characteristics. In this study, it is tried to make clear about inner composition of the servo driver through...

75 FR 32983 - Commercial Driver's License (CDL) Standards: Exemption

Science.gov (United States)

2010-06-10

...-28480] Commercial Driver's License (CDL) Standards: Exemption AGENCY: Federal Motor Carrier Safety... commercial driver's license (CDL) as required by current regulations. FMCSA reviewed NAAA's application for... demonstrate alternatives its members would employ to ensure that their commercial motor vehicle (CMV) drivers...

Drivers and moderators of business decline

Directory of Open Access Journals (Sweden)

Marius Pretorius

2010-12-01

Full Text Available Purpose: Reports of business failure elicit various reactions, while research in this domain often appears to be limited by a lack of access to information about failure and by the negativity that surrounds it. Those who have experienced failure do not readily talk about it, or they disappear from the radar screen of researchers. Yet failure is preceded by decline which, when focused on strategically, can reduce eventual failures if early action is taken. The main purpose of this study is to develop a conceptual framework or typology of the drivers and moderators of business decline. Design/methodology/approach: After applying the "grounded theory" approach to the academic literature on decline and failure, a conceptual framework for the variables that drive and moderate business decline is proposed. Findings: The study proposes that decline has three core drivers, three peripheral drivers and four moderators. The core drivers identified are: resource munificence; leadership as origin; and causality (strategic versus operational origin of decline. The three peripheral drivers are: unique preconditions; continuous decisions impact; and extremes dichotomy. The study describes four moderators of the drivers: life cycle stage; stakeholder perspective; quantitative versus qualitative nature of signs and causes; and finally the age and size effects. Research limitations/implications: The proposed conceptual framework is based on literature only, although it has found support during discussions with practitioners. It is proposed to readers of this journal for scrutiny and validation. Practical implications: Strategists need to understand what drives decline in order to act timeously; practitioners who have an insight into the moderators with their impacts could make better decisions in response to decline in organisations and possibly avoid business failure. Originality/Value: Understanding business decline is still a huge theoretical challenge, which

Tarantula: Killing driver bugs before they hatch

DEFF Research Database (Denmark)

Lawall, Julia Laetitia; Muller, Gilles; Urunuela, Richard

2005-01-01

The Linux operating system is undergoing continual evolution. Evolution in the kernel and generic driver modules often triggers the need for corresponding evolutions in specific device drivers. Such collateral evolutions are tedious, because of the large number of device drivers, and error......-prone, because of the complexity of the code modifications involved. We propose an automatic tool, Tarantula, to aid in this process. In this paper, we examine some recent evolutions in Linux and the collateral evolutions they trigger, and assess the corresponding requirements on Tarantula....

Physical characteristics of experienced and junior open-wheel car drivers.

Science.gov (United States)

Raschner, Christian; Platzer, Hans-Peter; Patterson, Carson

2013-01-01

Despite the popularity of open-wheel car racing, scientific literature about the physical characteristics of competitive race car drivers is scarce. The purpose of this study was to compare selected fitness parameters of experienced and junior open-wheel race car drivers. The experienced drivers consisted of five Formula One, two GP2 and two Formula 3 drivers, and the nine junior drivers drove in the Formula Master, Koenig, BMW and Renault series. The following fitness parameters were tested: multiple reactions, multiple anticipation, postural stability, isometric upper body strength, isometric leg extension strength, isometric grip strength, cyclic foot speed and jump height. The group differences were calculated using the Mann-Whitney U-test. Because of the multiple testing strategy used, the statistical significance was Bonferroni corrected and set at P < 0.004. Significant differences between the experienced and junior drivers were found only for the jump height parameter (P = 0.002). The experienced drivers tended to perform better in leg strength (P = 0.009), cyclic foot speed (P = 0.024) and grip strength (P = 0.058). None of the other variables differed between the groups. The results suggested that the experienced drivers were significantly more powerful than the junior drivers: they tended to be quicker and stronger (18% to 25%) but without statistical significance. The experienced drivers demonstrated excellent strength and power compared with other high-performance athletes.

Free electron laser as a fusion driver

International Nuclear Information System (INIS)

Prosnitz, D.; Schlitt, L.

1981-01-01

The Free Electron Laser (FEL) is shown to be a potentially attractive solution to the problem of finding a suitable short wavelength fusion driver. The design of a 3 MJ, 250 nm FEL fusion driver is discussed

Traffic safety issues in North Dakota : phase II : driver knowledge, attitude, behavior and beliefs : focus group : young male drivers

Science.gov (United States)

2008-10-01

Traffic safety is a widespread social concern. Tackling the problem requires understanding the people : who are driving. This includes information about driver behavior, but also about perceptions these drivers : hold regarding their driving. North D...

Detecting Driver Drowsiness Based on Sensors: A Review

Directory of Open Access Journals (Sweden)

Kenneth Sundaraj

2012-12-01

Full Text Available In recent years, driver drowsiness has been one of the major causes of road accidents and can lead to severe physical injuries, deaths and significant economic losses. Statistics indicate the need of a reliable driver drowsiness detection system which could alert the driver before a mishap happens. Researchers have attempted to determine driver drowsiness using the following measures: (1 vehicle-based measures; (2 behavioral measures and (3 physiological measures. A detailed review on these measures will provide insight on the present systems, issues associated with them and the enhancements that need to be done to make a robust system. In this paper, we review these three measures as to the sensors used and discuss the advantages and limitations of each. The various ways through which drowsiness has been experimentally manipulated is also discussed. We conclude that by designing a hybrid drowsiness detection system that combines non-intusive physiological measures with other measures one would accurately determine the drowsiness level of a driver. A number of road accidents might then be avoided if an alert is sent to a driver that is deemed drowsy.

Driver's mental workload prediction model based on physiological indices.

Science.gov (United States)

Yan, Shengyuan; Tran, Cong Chi; Wei, Yingying; Habiyaremye, Jean Luc

2017-09-15

Developing an early warning model to predict the driver's mental workload (MWL) is critical and helpful, especially for new or less experienced drivers. The present study aims to investigate the correlation between new drivers' MWL and their work performance, regarding the number of errors. Additionally, the group method of data handling is used to establish the driver's MWL predictive model based on subjective rating (NASA task load index [NASA-TLX]) and six physiological indices. The results indicate that the NASA-TLX and the number of errors are positively correlated, and the predictive model shows the validity of the proposed model with an R 2 value of 0.745. The proposed model is expected to provide a reference value for the new drivers of their MWL by providing the physiological indices, and the driving lesson plans can be proposed to sustain an appropriate MWL as well as improve the driver's work performance.

Theoretical models of drivers behavior on the road

Directory of Open Access Journals (Sweden)

Marcin Piotr Biernacki

2017-06-01

Full Text Available Understanding of mechanisms and factors responsible for the driver behavior on the road is the subject of ongoing interest to transportation psychologists, occupational doctors and engineers. Models of driver behavior are a key point for the understanding the mechanisms and factors which may cause limitations to the optimal functioning on the road. They also systematize knowledge about the factors responsible for the behavior of the driver and thus constitute a starting point for formulating empirical or diagnostic hypotheses. The aim of this study is to present models of driver behavior from the descriptive and functional perspectives. Med Pr 2017;68(3:401–411

Integrated Context-Aware Driver Assistance System Architecture

Directory of Open Access Journals (Sweden)

Elhadi M. Shakshuki

2013-01-01

Full Text Available Recently, significant improvements have been made in the area of vehicular communication systems. Furthermore, vehicle-to-vehicle communication is considered a key concept for keeping roads safe. An efficient implementation of these systems is necessary to ensure the safety of driving situations and to reduce the collision rates. This paper proposes a Context-Aware Driver Assistance System that links drivers with the physical environment surrounding them using multiple types of sensors and traffic systems as well as considering the senior driver's difficulties and the system processing time. This is achieved by developing a warning system that assists drivers to avoid collisions and improve their response times. The proposed system architecture consists of a set of components to process the user's request such as parking assistance, and to provide responses and advices when needed. These components include communication, knowledge exchange, knowledge update, and context-history. Also, it includes other processes such as context-history manipulation, hazard detection, and hazard detection control. The main goal of the proposed system is to reduce the number of car accidents and improve driver's decisions. The NXT Robotic environment is used to demonstrate the feasibility of the proposed system.

U.S. DOE driver development for ICF

International Nuclear Information System (INIS)

Sluyter, M.M.

1995-01-01

The goal of the Department of Energy (DOE) supported Inertial Confinement Fusion (ICF) Program is to produce pure fusion ignition with fusion yields of 200 to 1000 millions of joules, which could find several applications in the defence and in the electric power generation. The National Ignition Facility will operate in both direct and indirect driver modes, with a glass laser driver. However two other options have been developed to increase the energy efficiency: the Light Ion Pulsed Power program and the NIKE KrF laser. Heavy ion drivers are also investigated -Abstract only-. (TEC)

Will the Driver Seat Ever Be Empty?

OpenAIRE

Fraichard , Thierry

2014-01-01

Self-driving technologies have matured and improved to the point that, in the past few years, self-driving cars have been able to safely drive an impressive number of kilometers. It should be noted though that, in all cases, the driver seat was never empty: a human driver was behind the wheel, ready to take over whenever the situation dictated it. This is an interesting paradox since the point of a self-driving car is to remove the most unreliable part of the car, namely the human driver. So,...

Driver feedback mobile APP

Energy Technology Data Exchange (ETDEWEB)

Soriguera Marti, F.; Miralles Miquel, E.

2016-07-01

This paper faces the human factor in driving and its consequences for road safety. It presents the concepts behind the development of a smartphone app capable of evaluating drivers’ performance. The app provides feedback to the driver in terms of a grade (between 0 and 10) depending on the aggressiveness and risks taken while driving. These are computed from the cumulative probability distribution function of the jerks (i.e. the time derivative of acceleration), which are measured using the smartphones’ accelerometer. Different driving contexts (e.g. urban, freeway, congestion, etc.) are identified applying cluster analysis to the measurements, and treated independently. Using regression analysis, the aggressiveness indicator is related to the drivers' safety records and to the probability of having an accident, through the standard DBQ - Driving Behavior Questionnaire. Results from a very limited pilot test show a strong correlation between the 99th percentile of the jerk measurements and the DBQ results. A linear model is fitted. This allows quantifying the safe driving behavior only from smartphone measurements. Finally, this indicator is translated into a normalized grade and feedback to the driver. This feedback will challenge the driver to train and to improve his performance. The phone will be blocked while driving and will incorporate mechanisms to prevent bad practices, like competition in aggressive driving. The app is intended to contribute to the improvement of road safety, one of the major public health problems, by tackling the human factor which is the trigger of the vast majority of traffic accidents. Making explicit and quantifying risky behaviors is the first step towards a safer driving. (Author)

A novel active heads-up display for driver assistance.

Science.gov (United States)

Doshi, Anup; Cheng, Shinko Yuanhsien; Trivedi, Mohan Manubhai

2009-02-01

In this paper, we introduce a novel laser-based wide-area heads-up windshield display which is capable of actively interfacing with a human as part of a driver assistance system. The dynamic active display (DAD) is a unique prototype interface that presents safety-critical visual icons to the driver in a manner that minimizes the deviation of his or her gaze direction without adding to unnecessary visual clutter. As part of an automotive safety system, the DAD presents alerts in the field of view of the driver only if necessary, which is based upon the state and pose of the driver, vehicle, and environment. This paper examines the effectiveness of DAD through a comprehensive comparative experimental evaluation of a speed compliance driver assistance system, which is implemented on a vehicular test bed. Three different types of display protocols for assisting a driver to comply with speed limits are tested on actual roadways, and these are compared with a conventional dashboard display. Given the inclination, drivers who are given an overspeed warning alert reduced the time required to slow down to the speed limit by 38% (p system.

Estimating likelihood of future crashes for crash-prone drivers

OpenAIRE

Subasish Das; Xiaoduan Sun; Fan Wang; Charles Leboeuf

2015-01-01

At-fault crash-prone drivers are usually considered as the high risk group for possible future incidents or crashes. In Louisiana, 34% of crashes are repeatedly committed by the at-fault crash-prone drivers who represent only 5% of the total licensed drivers in the state. This research has conducted an exploratory data analysis based on the driver faultiness and proneness. The objective of this study is to develop a crash prediction model to estimate the likelihood of future crashes for the a...

Cedar Avenue driver assist system evaluation report.

Science.gov (United States)

2011-12-01

This paper summarizes an evaluation of the Driver Assist System (DAS) used by the Minnesota Valley Transit Authority (MTVA) for bus shoulder operations. The DAS is a GPS-based technology suite that provides lane-position feedback to the driver via a ...

PILOT RESULTS ON FORWARD COLLISION WARNING SYSTEM EFFECTIVENESS IN OLDER DRIVERS.

Science.gov (United States)

Lester, Benjamin D; Sager, Lauren N; Dawson, Jeffrey; Hacker, Sarah D; Aksan, Nazan; Rizzo, Matthew; Kitazaki, Satoshi

2015-06-01

Advanced Driver Assistance Systems (ADAS) have largely been developed with a "one-size-fits-all" approach. This approach neglects the large inter-individual variability in perceptual and cognitive abilities that affect aging ADAS users. We investigated the effectiveness of a forward collision warning (FCW) with fixed response parameters in young and older drivers with differing levels of cognitive functioning. Drivers responded to a pedestrian stepping into the driver's path on a simulated urban road. Behavioral metrics included response times (RT) for pedal controls and two indices of risk penetration (e.g., maximum deceleration and minimum time-to-collision (TTC)). Older drivers showed significantly slower responses at several time points compared to younger drivers. The FCW facilitated response times (RTs) for older and younger drivers. However, older drivers still showed smaller safety gains compared to younger drivers at accelerator pedal release and initial brake application when the FCW was active. No significant differences in risk metrics were observed within the condition studied. The results demonstrate older drivers likely differ from younger drivers using a FCW with a fixed parameter set. Finally, we briefly discuss how future research should examine predictive relationships between domains of cognitive functioning and ADAS responses to develop parameter sets to fit the individual.

The driver as archetype for driver assistance systems? A driver-model based approach for the development of situation-adaptive DAS; Der Fahrer als Vorbild fuer Fahrerassistenzsysteme? Ein Fahrermodellbasierter Ansatz zur Entwicklung von situationsadaptiven FAS

Energy Technology Data Exchange (ETDEWEB)

Benmimoun, A. [Inst. fuer Kraftfahrwesen, RWTH-Aachen, Aachen (Germany)

2004-07-01

A new approach for the development of advanced driver assistance systems is presented. The keynote of this new approach is to use the driver model of the traffic simulation tool PELOPS as a control algorithm and to apply it to a vehicle. The fact, that the human driving behaviour is the starting point of the development, is the main advantage of this new approach. Thus important aspects for the development of driver assistance systems like a situation-adaptive and reliable control, understandable behaviour and the consideration of driver-individual parameters are integrated in the controller design from the beginning. An application example of the new approach is shown. (orig.)

Secondary Behavior of Drivers on Cell Phones.

Science.gov (United States)

Farmer, Charles M; Klauer, Sheila G; McClafferty, Julie A; Guo, Feng

2015-01-01

The objective of this study was to determine whether cell phone use by drivers leads to changes in the frequency of other types of potentially distracting behavior. There were 2 main questions of interest: (1) As each driver changes cell phone use, does he or she change the amount of driving time spent on other distracting behavior? (2) As each driver changes cell phone use, does he or she change the amount of driving time spent looking away from the driving task? Day-to-day driving behavior of 105 volunteer subjects was monitored over a period of 1 year. The amount of driving time during each trip spent on tasks secondary to driving (or looking away from the driving task) was correlated to the amount of time on a cell phone, taking into account the relationships among trips taken by the same driver. Drivers spent 42% of the time engaging in at least one secondary activity. Drivers were talking on a cell phone 7% of the time, interacting in some other way with a cell phone 5% of the time, and engaging in some other secondary activity (sometimes in conjunction with cell phone use) 33% of the time. Other than cell phone use, the most common secondary activities were interacting with a passenger (12% of driving time), holding but not otherwise interacting with an object (6%), and talking/singing/dancing to oneself (5%). Drivers were looking straight forward 81% of the time, forward left or right 5% of time, in a mirror 4% of the time, and elsewhere (eyes off driving task) 10% of time. On average, for each 1 percentage point increase in cell phone talking, the other secondary behavior rate decreased by 0.28 percentage points (P cell phone interaction per trip, the other secondary behavior rate decreased by 0.08 percentage points (P =.0558), but the rate of eyes off driving task increased by 0.06 percentage points (P cell phone can be distracting from the driving task, other secondary activities can be equally or more distracting, at least as measured by eye glances

Young Drivers Perceptual Learning Styles Preferences and Traffic Accidents

Directory of Open Access Journals (Sweden)

Svetlana Čičević

2011-05-01

Full Text Available Young drivers are over-represented in crash and fatality statistics. One way of dealing with this problem is to achieve primary prevention through driver education and training. Factors of traffic accidents related to gender, age, driving experience, and self-assessments of safety and their relationship to perceptual learning styles (LS preferences have been analyzed in this study. The results show that auditory is the most prominent LS. Drivers in general, as well as drivers without traffic accidents favour visual and tactile LS. Both inexperienced and highly experienced drivers show relatively high preference of kinaesthetic style. Yet, taking into account driving experience we could see that the role of kinaesthetic LS is reduced, since individual LS has become more important. Based on the results of this study it can be concluded that a multivariate and multistage approach to driver education, taking into account differences in LS preferences, would be highly beneficial for traffic safety.

Microcontroller based driver alertness detection systems to detect drowsiness

Science.gov (United States)

Adenin, Hasibah; Zahari, Rahimi; Lim, Tiong Hoo

2018-04-01

The advancement of embedded system for detecting and preventing drowsiness in a vehicle is a major challenge for road traffic accident systems. To prevent drowsiness while driving, it is necessary to have an alert system that can detect a decline in driver concentration and send a signal to the driver. Studies have shown that traffc accidents usually occur when the driver is distracted while driving. In this paper, we have reviewed a number of detection systems to monitor the concentration of a car driver and propose a portable Driver Alertness Detection System (DADS) to determine the level of concentration of the driver based on pixelated coloration detection technique using facial recognition. A portable camera will be placed at the front visor to capture facial expression and the eye activities. We evaluate DADS using 26 participants and have achieved 100% detection rate with good lighting condition and a low detection rate at night.

Pattern of Eye Diseases among Commercial Intercity Vehicle Drivers ...

African Journals Online (AJOL)

Objective: To determine the pattern of eye diseases among commercial intercity vehicle drivers (CIVDs) in Ilorin, Nigeria. Design: A cross-sectional descriptive study. Methodology: Out of the estimated 450 drivers operating in the five major motor parks for CIVDs in Ilorin, 399 consecutive drivers participated in the study.

The case for driver science in motorsport: a review and recommendations.

Science.gov (United States)

Potkanowicz, Edward S; Mendel, Ronald W

2013-07-01

When discussing sports and the athletes who participate in them, it has long been recognized that fitness is a prerequisite for optimal performance. The goal of training to improve fitness levels in athletes is ultimately to minimize the stress that the body experiences during competition. When it comes to the topic of racecar drivers, however, drivers and their trainers have largely been left to their own devices to figure out the stressors and the areas of specific training focus. Unfortunately, racecar drivers have battled the stereotype that they are not athletes, and with little regard for them as athletes, drivers are seldom the focus of scientific research related to their performance. Like the cars they drive, driver-athletes are complex, but from a physiological perspective. However, unlike the cars they drive, driver-athletes have not been examined, evaluated, and tweaked to the same degree. The purpose of this review is two-fold: first, by examining the available literature, to make the case for new research into the driver's role in the driver-car system (i.e. driver science) and the stresses experienced; second, to make the case for more extensive use of microtechnology in the real-time monitoring of driver-athletes. With the miniaturization of sensors and the advent of portable data storage devices, the prospect of quantifying the stresses unique to the driver are no longer as daunting, and the relative impossibility and difficulties associated with measuring the driver-athlete in real-time no longer need to be as challenging. Using microtechnology in the assessment of the driver-athlete and with a more public discussion and dissemination of information on the topic of driver science, the scientific community has the opportunity to quantify that which has been largely assumed and speculated. The current article will offer the following recommendations: first, rather than examining a singular physiological stressor, to examine the interaction of

Vehicle and driver scheduling for public transit.

Science.gov (United States)

2009-08-01

The problem of driver scheduling involves the construction of a legal set of shifts, including allowance : of overtime, which cover the blocks in a particular vehicle schedule. A shift is the work scheduled to be performed by : a driver in one day, w...

Complex-enhanced chaotic signals with time-delay signature suppression based on vertical-cavity surface-emitting lasers subject to chaotic optical injection

Science.gov (United States)

Chen, Jianjun; Duan, Yingni; Zhong, Zhuqiang

2018-03-01

A chaotic system is constructed on the basis of vertical-cavity surface-emitting lasers (VCSELs), where a slave VCSEL subject to chaotic optical injection (COI) from a master VCSEL with the external feedback. The complex degree (CD) and time-delay signature (TDS) of chaotic signals generated by this chaotic system are investigated numerically via permutation entropy (PE) and self-correlation function (SF) methods, respectively. The results show that, compared with master VCSEL subject to optical feedback, complex-enhanced chaotic signals with TDS suppression can be achieved for S-VCSEL subject to COI. Meanwhile, the influences of several controllable parameters on the evolution maps of CD of chaotic signals are carefully considered. It is shown that the CD of chaotic signals for S-VCSEL is always higher than that for M-VCSEL due to the CIO effect. The TDS of chaotic signals can be significantly suppressed by choosing the reasonable parameters in this system. Furthermore, TDS suppression and high CD chaos can be obtained simultaneously in the specific parameter ranges. The results confirm that this chaotic system may effectively improve the security of a chaos-based communication scheme.

European advanced driver training programs: Reasons for optimism

Directory of Open Access Journals (Sweden)

Simon Washington

2011-03-01

This paper reviews the predominant features and empirical evidence surrounding post licensing advanced driver training programs focused on novice drivers. A clear articulation of differences between the renewed and current US advanced driver training programs is provided. While the individual quantitative evaluations range from marginally to significantly effective in reducing novice driver crash risk, they have been criticized for evaluation deficiencies ranging from small sample sizes to confounding variables to lack of exposure metrics. Collectively, however, the programs sited in the paper suggest at least a marginally positive effect that needs to be validated with further studies. If additional well controlled studies can validate these programs, a pilot program in the US should be considered.

Key drivers of airline loyalty.

Science.gov (United States)

Dolnicar, Sara; Grabler, Klaus; Grün, Bettina; Kulnig, Anna

2011-10-01

This study investigates drivers of airline loyalty. It contributes to the body of knowledge in the area by investigating loyalty for a number of a priori market segments identified by airline management and by using a method which accounts for the multi-step nature of the airline choice process. The study is based on responses from 687 passengers. Results indicate that, at aggregate level, frequent flyer membership, price, the status of being a national carrier and the reputation of the airline as perceived by friends are the variables which best discriminate between travellers loyal to the airline and those who are not. Differences in drivers of airline loyalty for a number of segments were identified. For example, loyalty programs play a key role for business travellers whereas airline loyalty of leisure travellers is difficult to trace back to single factors. For none of the calculated models satisfaction emerged as a key driver of airline loyalty.

A RE-ASSESSMENT OF OLDER DRIVERS AS A ROAD SAFETY RISK

Directory of Open Access Journals (Sweden)

Jim LANGFORD

2006-01-01

Full Text Available Older drivers are frequently viewed as overly represented in crashes, particularly when crash involvement per distance travelled is considered. This perception has led to a call for tighter licensing conditions for older drivers, a policy which inevitably results in mobility restrictions for at least some drivers. However there is a growing body of research evidence which shows that as a group, older drivers represent no greater road risk than drivers from other age groups once different levels of driving activity are taken into account. This paper has examined aspects of older drivers' fitness to drive based on survey data and off-road and on-road driving performance from a sample of 905 New Zealand older drivers. The results show that policies which target all older drivers and lead to licensing and mobility restrictions cannot be justified from a safety basis.

Crash probability estimation via quantifying driver hazard perception.

Science.gov (United States)

Li, Yang; Zheng, Yang; Wang, Jianqiang; Kodaka, Kenji; Li, Keqiang

2018-07-01

Crash probability estimation is an important method to predict the potential reduction of crash probability contributed by forward collision avoidance technologies (FCATs). In this study, we propose a practical approach to estimate crash probability, which combines a field operational test and numerical simulations of a typical rear-end crash model. To consider driver hazard perception characteristics, we define a novel hazard perception measure, called as driver risk response time, by considering both time-to-collision (TTC) and driver braking response to impending collision risk in a near-crash scenario. Also, we establish a driving database under mixed Chinese traffic conditions based on a CMBS (Collision Mitigation Braking Systems)-equipped vehicle. Applying the crash probability estimation in this database, we estimate the potential decrease in crash probability owing to use of CMBS. A comparison of the results with CMBS on and off shows a 13.7% reduction of crash probability in a typical rear-end near-crash scenario with a one-second delay of driver's braking response. These results indicate that CMBS is positive in collision prevention, especially in the case of inattentive drivers or ole drivers. The proposed crash probability estimation offers a practical way for evaluating the safety benefits in the design and testing of FCATs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Intersection assistance: a safe solution for older drivers?

Science.gov (United States)

Dotzauer, Mandy; Caljouw, Simone R; de Waard, Dick; Brouwer, Wiebo H

2013-10-01

Within the next few decades, the number of older drivers operating a vehicle will increase rapidly (Eurostat, 2011). As age increases so does physical vulnerability, age-related impairments, and the risk of being involved in a fatal crashes. Older drivers experience problems in driving situations that require divided attention and decision making under time pressure as reflected by their overrepresentation in at-fault crashes on intersections. Advanced Driver Assistance Systems (ADAS) especially designed to support older drivers crossing intersections might counteract these difficulties. In a longer-term driving simulator study, the effects of an intersection assistant on driving were evaluated. 18 older drivers (M=71.44 years) returned repeatedly completing a ride either with or without a support system in a driving simulator. In order to test the intersection assistance, eight intersections were depicted for further analyses. Results show that ADAS affects driving. Equipped with ADAS, drivers allocated more attention to the road center rather than the left and right, crossed intersections in shorter time, engaged in higher speeds, and crossed more often with a critical time-to-collision (TTC) value. The implications of results are discussed in terms of behavioral adaptation and safety. Copyright © 2013 Elsevier Ltd. All rights reserved.

Coupling in reflector arrays

DEFF Research Database (Denmark)

Appel-Hansen, Jørgen

1968-01-01

In order to reduce the space occupied by a reflector array, it is desirable to arrange the array antennas as close to each other as possible; however, in this case coupling between the array antennas will reduce the reflecting properties of the reflector array. The purpose of the present communic......In order to reduce the space occupied by a reflector array, it is desirable to arrange the array antennas as close to each other as possible; however, in this case coupling between the array antennas will reduce the reflecting properties of the reflector array. The purpose of the present...

Driver's anger state identification by using facial expression in ...

African Journals Online (AJOL)

Preventive safety system of vehicle is highlighted to reduce the number of traffic accidents. Driver's state adaptive driving safety system may be one of candidates of the safety system. Identifying driver's psychosomatic states is indispensable to establish those safety systems. Anger of driver state is often seen in traffic ...

Vertical-cavity surface-emitting lasers for medical diagnosis

DEFF Research Database (Denmark)

Ansbæk, Thor

This thesis deals with the design and fabrication of tunable Vertical-Cavity Surface-Emitting Lasers (VCSELs). The focus has been the application of tunable VCSELs in medical diagnostics, specifically OCT. VCSELs are candidates as light sources for swept-source OCT where their high sweep rate, wide...

Steering disturbance rejection using a physics-based neuromusculoskeletal driver model

Science.gov (United States)

Mehrabi, Naser; Sharif Razavian, Reza; McPhee, John

2015-10-01

The aim of this work is to develop a comprehensive yet practical driver model to be used in studying driver-vehicle interactions. Drivers interact with their vehicle and the road through the steering wheel. This interaction forms a closed-loop coupled human-machine system, which influences the driver's steering feel and control performance. A hierarchical approach is proposed here to capture the complexity of the driver's neuromuscular dynamics and the central nervous system in the coordination of the driver's upper extremity activities, especially in the presence of external disturbance. The proposed motor control framework has three layers: the first (or the path planning) plans a desired vehicle trajectory and the required steering angles to perform the desired trajectory; the second (or the musculoskeletal controller) actuates the musculoskeletal arm to rotate the steering wheel accordingly; and the final layer ensures the precision control and disturbance rejection of the motor control units. The physics-based driver model presented here can also provide insights into vehicle control in relaxed and tensed driving conditions, which are simulated by adjusting the driver model parameters such as cognition delay and muscle co-contraction dynamics.

ITER driver blanket, European Community design

International Nuclear Information System (INIS)

Simbolotti, G.; Zampaglione, V.; Ferrari, M.; Gallina, M.; Mazzone, G.; Nardi, C.; Petrizzi, L.; Rado, V.; Violante, V.; Daenner, W.; Lorenzetto, P.; Gierszewski, P.; Grattarola, M.; Rosatelli, F.; Secolo, F.; Zacchia, F.; Caira, M.; Sorabella, L.

1993-01-01

Depending on the final decision on the operation time of ITER (International Thermonuclear Experimental Reactor), the Driver Blanket might become a basic component of the machine with the main function of producing a significant fraction (close to 0.8) of the tritium required for the ITER operation, the remaining fraction being available from external supplies. The Driver Blanket is not required to provide reactor relevant performance in terms of tritium self-sufficiency. However, reactor relevant reliability and safety are mandatory requirements for this component in order not to significantly afftect the overall plant availability and to allow the ITER experimental program to be safely and successfully carried out. With the framework of the ITER Conceptual Design Activities (CDA, 1988-1990), a conceptual design of the ITER Driver Blanket has been carried out by ENEA Fusion Dept., in collaboration with ANSALDO S.p.A. and SRS S.r.l., and in close consultation with the NET Team and CFFTP (Canadian Fusion Fuels Technology Project). Such a design has been selected as EC (European Community) reference design for the ITER Driver Blanket. The status of the design at the end of CDA is reported in the present paper. (orig.)

SSCL DD2 driver port and project update

International Nuclear Information System (INIS)

Mestad, S.L.

1994-01-01

A paper previously published in the 1992 ICHEP proceedings outlined the SSC's need for a high speed, high capacity tape drive to store detector data. Also described were stages and lessons learned while developing a custom device driver for the Ampex DD2 tape drive on a Silicon Graphics 4D/310. This paper updates the work on the SGI driver and describes the efforts in porting the driver to a Sun Microsystems 670 server

SSCL DD2 driver port and project update

International Nuclear Information System (INIS)

Mestad, S.L.

1993-04-01

A paper previously published in the 1992 ICHEP proceedings outlined the SSC's need for a high speed, high capacity tape drive to store detector data. Also described were stages and lessons learned while developing a custom device driver for the Ampex DD2 tape drive on a Silicon Graphics 4D/310. This paper updates the work on the SGI driver and describes the efforts in porting the driver to a Sun Microsystems 670 server

SUBJECTIVE METHODS FOR ASSESSMENT OF DRIVER DROWSINESS

Directory of Open Access Journals (Sweden)

Alina Mashko

2017-12-01

Full Text Available The paper deals with the issue of fatigue and sleepiness behind the wheel, which for a long time has been of vital importance for the research in the area of driver-car interaction safety. Numerous experiments on car simulators with diverse measurements to observe human behavior have been performed at the laboratories of the faculty of the authors. The paper provides analysis and an overview and assessment of the subjective (self-rating and observer rating methods for observation of driver behavior and the detection of critical behavior in sleep deprived drivers using the developed subjective rating scales.

Cyclist-related content in novice driver education and training.

Science.gov (United States)

Bonham, Jennifer; Johnson, Marilyn

2018-02-01

In Australia, the increasing public profile and policy interest in cycling contrasts with variable cycling participation rates across jurisdictions (Australian Bicycle Council, 2017) and lack of cyclist-specific infrastructure. Cyclists and drivers often share road space, usually without indication from the built environment about how to maximise each other's safety and utility. Yet despite this regular interaction, cyclists are largely absent from the driver licensing process in Australia. That is, novice drivers are not taught how to share the road with cyclists. This case study used a mixed methods approach to examine the cyclist-related content in the Graduated Driver Licensing System (GDLS) in the Australian Capital Territory (ACT). The case study was conducted in four stages: 1) content analysis of all documents used through the GDLS; 2) observations of the Road Ready course and learner driver lessons; 3) online survey; and, 4) semi-structured interviews. Cyclists are rarely mentioned in the GDLS in the ACT and references often constructed cyclists as problematic or were based in instructors' personal opinion (rather than scripted responses). Outcomes from this study have directly informed a new vulnerable road user driver licence competency in the ACT and findings include recommendations for greater inclusion of cyclists in the driver licensing system. Copyright © 2017 Elsevier Ltd. All rights reserved.

Induction linac drivers for commercial heavy-ion beam fusion

International Nuclear Information System (INIS)

Keefe, D.

1987-11-01

This paper discusses induction linac drivers necessary to accelerate heavy ions at inertial fusion targets. Topics discussed are: driver configurations, the current-amplifying induction linac, high current beam behavior and emittance growth, new considerations for driver design, the heavy ion fusion systems study, and future studies. 13 refs., 6 figs., 1 tab

An evidence-based review: distracted driver.

Science.gov (United States)

Llerena, Luis E; Aronow, Kathy V; Macleod, Jana; Bard, Michael; Salzman, Steven; Greene, Wendy; Haider, Adil; Schupper, Alex

2015-01-01

Cell phone use and texting are prevalent within society and have thus pervaded the driving population. This technology is a growing concern within the confines of distracted driving, as all diversions from attention to the road have been shown to increase the risk of crashes. Adolescent, inexperienced drivers, who have the greatest prevalence of texting while driving, are at a particularly higher risk of crashes because of distraction. Members of the Injury Control Violence Prevention Committee of the Eastern Association for the Surgery of Trauma performed a PubMed search of articles related to distracted driving and cell phone use as a distractor of driving between 2000 and 2013. A total of 19 articles were found to merit inclusion as evidence in the evidence-based review. These articles provided evidence regarding the relationship between distracted driving and crashes, cell phone use contributing to automobile accidents, and/or the relationship between driver experience and automobile accidents. (Adjust methods/results sections to the number of articles that correctly corresponds to the number of references, as well as the methodology for reference inclusion.) Based on the evidence reviewed, we can recommend the following. All drivers should minimize all in-vehicle distractions while on the road. All drivers should not text or use any touch messaging system (including the use of social media sites such as Facebook and Twitter) while driving. Younger, inexperienced drivers should especially not use cell phones, texting, or any touch messaging system while driving because they pose an increased risk for death and injury caused by distractions while driving.

Viruses are a dominant driver of protein adaptation in mammals.

Science.gov (United States)

Enard, David; Cai, Le; Gwennap, Carina; Petrov, Dmitri A

2016-05-17

Viruses interact with hundreds to thousands of proteins in mammals, yet adaptation against viruses has only been studied in a few proteins specialized in antiviral defense. Whether adaptation to viruses typically involves only specialized antiviral proteins or affects a broad array of virus-interacting proteins is unknown. Here, we analyze adaptation in ~1300 virus-interacting proteins manually curated from a set of 9900 proteins conserved in all sequenced mammalian genomes. We show that viruses (i) use the more evolutionarily constrained proteins within the cellular functions they interact with and that (ii) despite this high constraint, virus-interacting proteins account for a high proportion of all protein adaptation in humans and other mammals. Adaptation is elevated in virus-interacting proteins across all functional categories, including both immune and non-immune functions. We conservatively estimate that viruses have driven close to 30% of all adaptive amino acid changes in the part of the human proteome conserved within mammals. Our results suggest that viruses are one of the most dominant drivers of evolutionary change across mammalian and human proteomes.

Driver behaviour in motorway car-following transitions and driver support systems

NARCIS (Netherlands)

Feenstra, P.; Horst, A.R.A. van der

2006-01-01

Co-operative driving with speed adaptation functionality has great potential to improve traffic-throughput, traffic-safety, and environmental-impact on heavily used traffic-infrastructures. A driving-simulator study was performed to investigate the driver behaviour with respect to such

Traffic Safety through Driver Assistance and Intelligence

Directory of Open Access Journals (Sweden)

Heiner Bubb

2011-05-01

BMW, Daimler, Audi, Citroen, Lexus, VW, Opel, Peugeot, Renault, Chevrolet, Saab and Bosch. Both the contributions of research work concerning driving behavior analysis and driver assistance systems have to be aligned with a permanently updated interaction within the system of driver, vehicle and road traffic environment.

Continuous traffic flow modeling of driver support systems in multiclass traffic with intervehicle communication and drivers in the loop

NARCIS (Netherlands)

Tampere, C.; Hoogendoorn, S.P.; van Arem, Bart

2009-01-01

This paper presents a continuous traffic-flow model for the explorative analysis of advanced driver-assistance systems (ADASs). Such systems use technology (sensors and intervehicle communication) to support the task of the driver, who retains full control over the vehicle. Based on a review of

Mandatory Driver Training and Road Safety: The Quebec Experience.

Science.gov (United States)

Potvin, Louise; And Others

1988-01-01

1983 legislation making driver training courses mandatory for any person in Quebec seeking a first driver's license had no effect on the risk of accident or the mortality/morbidity rate for newly licensed drivers over 18. However, since 1983 more women under 18 are becoming licensed, and their risks may be increased. (Author/BJV)

The micro-step motor controller protocol and driver

International Nuclear Information System (INIS)

Hong, Kwang Pyo; Lee, Chang Hee; Moon, Myung Kook; Choi, Bung Hun; Choi, Young Hyun; Cheon, Jong Gu

2004-11-01

We developed the communication protocol which is a main kernel of motor control firmware program that is used at HANARO neutron spectrometer now. This protocol driver divide into as a 4 group(Serial protocol, DLL, Active-X, Labview driver), so end-user can control the motor control as easily by PC RS232/422 port and have a merits as follows: Support a Low Level/High level driver, Support a Network Connectivity function by using High level Driver, One Server can services many client request. By using this protocol, The End-user can be easily makes a application motor control program and developed another application system program by using several kinds of programming tools under Widows and Linux based operation systems

Road Rage Menace: A Cross-sectional Study to Assess Driver Anger Level in Public Motor Vehicle Drivers in a City in Central India

Directory of Open Access Journals (Sweden)

Sanjay Dixit

2011-07-01

Full Text Available Introduction: Road rage and aggressive driving is a prevalent condition in today’s society due to motorists’ frustrations during heavy traffic volumes. Objective: This study was done to assess the level of anger amongst the drivers of public transport vehicles in Indore, using Driving Anger Scale (DAS by Deffenbacher et. al. and various factors affecting it. Material and Methods: A cross-sectional study was conducted among 135 drivers of Public transport vehicle drivers (Star bus, City-van and star cab drivers in Indore to assess their anger level using Driving Anger Scale. The participants were required to record the amount of anger they would experience in response to each item in the scale (1=not at all angry, 2=a little angry, 3=some anger, 4=much anger, 5=very much angry. Results: The mean DAS score in Indore was found to be 3.013 and in the three organizations namely Star bus drivers, City van drivers and Star cab drivers was 2.92, 3.08 and 3.04 respectively. The DAS score of drivers with respect to the 6 sub-scales were: hostile gestures (Star bus -3.42,City van -3.67,Star cab -3.38, slow driving (Star bus -2.73,City van driv-2.78,Star cab-3.17, traffic obstructions (Star bus-2.85,City van -3.25,Star cab-3.18, discourtesy (Star bus -3.23,City van-3.33,Star cab -3.25and police presence (Star bus -2.15,City van -1.99,Star cab -2.78, illegal driving (Star bus -3.04,City van -3.14,Star cab -2.89. The DAS scores of the drivers did not vary significantly with age group, experience, and educational qualification. Conclusion: Though DAS scores did not vary between the three groups of drivers, however average level anger for various given circumstances commonly found in the Indian traffic scenario was on the higher side.

Cooperative advanced Driver assistance Systems - Technological measures for data privacy compliance

OpenAIRE

Jäger, Hubert; Schnieder, Lars

2016-01-01

Cooperative advanced driver assistance systems (ADAS) will contribute to road traffic safety: Critical situations will be detected, the driver alerted and control of the vehicle interfered with automatically. However, the introduction of such driver assistance systems presupposes that data privacy issues have already been solved in advance. A necessary condition for the driver to accept and trust new Driver assistance systems is that his/her personal and personally identifiable data will be t...

Concurrent array-based queue

Science.gov (United States)

Heidelberger, Philip; Steinmacher-Burow, Burkhard

2015-01-06

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

Combining coordination of motion actuators with driver steering interaction.

Science.gov (United States)

Tagesson, Kristoffer; Laine, Leo; Jacobson, Bengt

2015-01-01

A new method is suggested for coordination of vehicle motion actuators; where driver feedback and capabilities become natural elements in the prioritization. The method is using a weighted least squares control allocation formulation, where driver characteristics can be added as virtual force constraints. The approach is in particular suitable for heavy commercial vehicles that in general are over actuated. The method is applied, in a specific use case, by running a simulation of a truck applying automatic braking on a split friction surface. Here the required driver steering angle, to maintain the intended direction, is limited by a constant threshold. This constant is automatically accounted for when balancing actuator usage in the method. Simulation results show that the actual required driver steering angle can be expected to match the set constant well. Furthermore, the stopping distance is very much affected by this set capability of the driver to handle the lateral disturbance, as expected. In general the capability of the driver to handle disturbances should be estimated in real-time, considering driver mental state. By using the method it will then be possible to estimate e.g. stopping distance implied from this. The setup has the potential of even shortening the stopping distance, when the driver is estimated as active, this compared to currently available systems. The approach is feasible for real-time applications and requires only measurable vehicle quantities for parameterization. Examples of other suitable applications in scope of the method would be electronic stability control, lateral stability control at launch and optimal cornering arbitration.

THE RELATION BETWEEN DRIVER BEHAVIOR AND INTELLIGENT TRANSPORT SYSTEM

Directory of Open Access Journals (Sweden)

Alica Kalašová

2017-12-01

Full Text Available The main objective of Slovakia’s transport policy is to reduce the number of traffic accidents and increase safety on our roads. Implementation of intelligent transport systems presents one of the possibilities how to meet this goal. Acceptance of these systems by motor vehicle drivers and other road traffic participants is necessary in order for them to fulfill their purpose. Only if the drivers will accept intelligent transport systems, it is possible to flexibly and effectively manage road traffic flexibly and effectively. From the perspective of a driver it concerns, in particular, the possibility of using alternative routes when traffic accidents or other obstacles occurs on the route that would significantly affect the continuity and safety of road traffic. Thanks to these technologies, it is possible to choose the appropriate route while driving, of course based on the criterion, which the driver considers the most important during the transport from origin to destination (driving time, distance from origin to destination, fuel consumption, quality of infrastructure. Information isare provided to the driver through variable message signs or directly in the vehicle (RDS-TMC. Another advantage of intelligent transport systems is a positive impact on psychological well-being of the driver while driving. Additional information about the possible obstacles, weather conditions and dangerous situations that occur on the roads as well as alternative routes are provided to the driver well in advance. This paper is mainly focused on how the drivers perceive the influence of intelligent transport systems in Žilina region.

Highly automated driving, secondary task performance, and driver state.

Science.gov (United States)

Merat, Natasha; Jamson, A Hamish; Lai, Frank C H; Carsten, Oliver

2012-10-01

A driving simulator study compared the effect of changes in workload on performance in manual and highly automated driving. Changes in driver state were also observed by examining variations in blink patterns. With the addition of a greater number of advanced driver assistance systems in vehicles, the driver's role is likely to alter in the future from an operator in manual driving to a supervisor of highly automated cars. Understanding the implications of such advancements on drivers and road safety is important. A total of 50 participants were recruited for this study and drove the simulator in both manual and highly automated mode. As well as comparing the effect of adjustments in driving-related workload on performance, the effect of a secondary Twenty Questions Task was also investigated. In the absence of the secondary task, drivers' response to critical incidents was similar in manual and highly automated driving conditions. The worst performance was observed when drivers were required to regain control of driving in the automated mode while distracted by the secondary task. Blink frequency patterns were more consistent for manual than automated driving but were generally suppressed during conditions of high workload. Highly automated driving did not have a deleterious effect on driver performance, when attention was not diverted to the distracting secondary task. As the number of systems implemented in cars increases, an understanding of the implications of such automation on drivers' situation awareness, workload, and ability to remain engaged with the driving task is important.

29 CFR 541.504 - Drivers who sell.

Science.gov (United States)

2010-07-01

... DELIMITING THE EXEMPTIONS FOR EXECUTIVE, ADMINISTRATIVE, PROFESSIONAL, COMPUTER AND OUTSIDE SALES EMPLOYEES Outside Sales Employees § 541.504 Drivers who sell. (a) Drivers who deliver products and also sell such products may qualify as exempt outside sales employees only if the employee has a primary duty of making...

High speed CAMAC differential branch highway driver

International Nuclear Information System (INIS)

McMillan, D.E.; Nelson, R.O.; Poore, R.V.; Sunier, J.W.; Ross, J.J.

1979-01-01

A new CAMAC branch driver is described that incorporates several unusual features which combine to give reliable, high-speed performance. These include balanced line driver/receivers, stored CAMAC command lists, 8 DMA channels, pseudo LAMS, hardware priority encoding of LAMS, and hardware-implemented Q-controlled block transfers. 3 figures

The impact of later trading hours for hotels on levels of impaired driver road crashes and driver breath alcohol levels.

Science.gov (United States)

Chikritzhs, Tanya; Stockwell, Tim

2006-09-01

To examine the impact of later trading hours for licensed hotels in Perth, Western Australia on levels of associated impaired driver road crashes and driver breath alcohol levels (BALs). Police data on the "last place of drinking" for impaired drivers involved in road crashes and their corresponding BALs were examined to identify those associated with Perth hotels between 1 July 1990 and 30 June 1997. During this period, 43 (23%) of the 186 hotels meeting study criteria were granted an Extended Trading Permit for 1 a.m. closing (ETP hotels), while the rest continued to close at midnight (non-ETP hotels). Time-series analyses employing multiple linear regressions were applied to determine whether an association existed between the introduction of extended trading and (i) monthly levels of impaired driver road crashes associated with ETP hotels and (ii) driver BALs associated with ETP hotels. Trends associated with non-ETP hotels were included as controls and possible confounders were considered. After controlling for the trend in crash rates associated with non-ETP hotels and the introduction of mobile police breath testing stations to Perth freeways, a significant increase in monthly crash rates for ETP hotels was found. This relationship was largely accounted for by higher volumes of high-alcohol content beer, wine and spirits purchased by ETP hotels. No relation was found between driver BALs and the introduction of ETPs. Late trading was associated with increased levels of impaired driver road crashes and alcohol consumption, particularly high-risk alcoholic beverages. Greater numbers of patrons and characteristics specific to clientele of hotels which applied for late trading hours (i.e. younger age, greater propensity to drunk-drive, preference for high-risk beverages) were suggested as having contributed to this increase.

Effectiveness of Taxicab Security Equipment in Reducing Driver Homicide Rates

Science.gov (United States)

Menéndez, Cammie K.C.; Amandus, Harlan E.; Damadi, Parisa; Wu, Nan; Konda, Srinivas; Hendricks, Scott A.

2015-01-01

Background Taxicab drivers historically have had one of the highest work-related homicide rates of any occupation. In 2010 the taxicab driver homicide rate was 7.4 per 100,000 drivers, compared to the overall rate of 0.37 per 100,000 workers. Purpose Evaluate the effectiveness of taxicab security cameras and partitions on citywide taxicab driver homicide rates. Methods Taxicab driver homicide rates were compared in 26 major cities in the U.S. licensing taxicabs with security cameras (n=8); bullet-resistant partitions (n=7); and cities where taxicabs were not equipped with either security cameras or partitions (n=11). News clippings of taxicab driver homicides and the number of licensed taxicabs by city were used to construct taxicab driver homicide rates spanning 15 years (1996–2010). Generalized estimating equations were constructed to model the Poisson-distributed homicide rates on city-specific safety equipment installation status, controlling for city homicide rate and the concurrent decline of homicide rates over time. Data were analyzed in 2012. Results Cities with cameras experienced a threefold reduction in taxicab driver homicides compared with control cities (RR=0.27; 95% CI=0.12, 0.61; p=0.002). There was no difference in homicide rates for cities with partitions compared with control cities (RR=1.15; 95% CI=0.80, 1.64; p=0.575). Conclusions Municipal ordinances and company policies mandating security cameras appear to be highly effective in reducing taxicab driver deaths due to workplace violence. PMID:23790983

Observed and projected drivers of emerging infectious diseases in Europe.

Science.gov (United States)

Semenza, Jan C; Rocklöv, Joacim; Penttinen, Pasi; Lindgren, Elisabet

2016-10-01

Emerging infectious diseases are of international concern because of the potential for, and impact of, pandemics; however, they are difficult to predict. To identify the drivers of disease emergence, we analyzed infectious disease threat events (IDTEs) detected through epidemic intelligence collected at the European Centre for Disease Prevention and Control (ECDC) between 2008 and 2013, and compared the observed results with a 2008 ECDC foresight study of projected drivers of future IDTEs in Europe. Among 10 categories of IDTEs, foodborne and waterborne IDTEs were the most common, vaccine-preventable IDTEs caused the highest number of cases, and airborne IDTEs caused the most deaths. Observed drivers for each IDTE were sorted into three main groups: globalization and environmental drivers contributed to 61% of all IDTEs, public health system drivers contributed to 21%, and social and demographic drivers to 18%. A multiple logistic regression analysis showed that four of the top five drivers for observed IDTEs were in the globalization and environment group. In the observational study, the globalization and environment group was related to all IDTE categories, but only to five of eight categories in the foresight study. Directly targeting these drivers with public health interventions may diminish the chances of IDTE occurrence from the outset. © 2016 New York Academy of Sciences.

Dominant role of drivers' attitude in prevention of road traffic crashes: a study on knowledge, attitude, and practice of drivers in Iran.

Science.gov (United States)

Mirzaei, Ramazan; Hafezi-Nejad, Nima; Sadegh Sabagh, Mohammad; Ansari Moghaddam, Alireza; Eslami, Vahid; Rakhshani, Fatemeh; Rahimi-Movaghar, Vafa

2014-05-01

Evaluating the relation between Iranian drivers' knowledge, attitude, and practice (KAP) regarding traffic regulations, and their deterministic effect on road traffic crashes (RTCs). Two cities of Tehran and Zahedan, Iran. A cross-sectional study was designed. Using a simplified cluster sampling design, 2200 motor vehicle drivers including 1200 in Tehran and 1000 in Zahedan were selected. Sixty locations in Tehran and 50 in Zahedan were chosen. In each pre-identified location, 20 adult drivers were approached consecutively. A questionnaire developed by researchers was filled by each participant. The questionnaire had four sections including items assessing the demographics, knowledge, attitude and practice of drivers toward traffic regulations. Logistic regression analysis was used to evaluate the relationship between the RTCs and KAP variables. The study sample consisted of 619 (28.1%) occupational and 1580 (71.8%) private drivers. Among them, 86.4% were male. The median age was 33.6 ± 10.83. Drivers in Tehran and Zahedan had no significant differences between their mean scores of KAP items of the questionnaire. Higher knowledge, safer attitude, and safer practice were associated with a decreased number of RTC. After adjusting for possible confounders, increase of one standard deviation in attitude and practice scores (but not knowledge) resulted in 26.4% and 18.5% decrease in RTC, respectively. Finally, considering knowledge, attitude and practice of drivers in one model to assess their mutual effect, it was shown that only attitude is significantly associated with a decrease of RTC (OR=0.76, P=0.007). Increase in attitude and practice accompanied with decreased number of RTCs in Iranian drivers. Specifically, drivers' attitude had the crucial effect. It is not knowledge and standard traffic education; rather it is how such education is registered as an attitude that translates what is being learned into actions. Without safer attitude, even safer self

Lower back pain and absenteeism among professional public transport drivers.

Science.gov (United States)

Kresal, Friderika; Roblek, Vasja; Jerman, Andrej; Meško, Maja

2015-01-01

Drivers in public transport are subjected to lower back pain. The reason for the pain is associated with the characteristics of the physical position imposed on the worker while performing the job. Lower back pain is the main cause of absenteeism among drivers. The present study includes 145 public transport drivers employed as professional drivers for an average of 14.14 years. Analysis of the data obtained in the study includes the basic descriptive statistics, χ(2) test and multiple regression analysis. Analysis of the incidence of lower back pain showed that the majority of our sample population suffered from pain in the lower back. We found that there are no statistically significant differences between the groups formed by the length of service as a professional driver and incidence of lower back pain; we were also interested in whether or not the risk factors of lower back pain affects the absenteeism of city bus drivers. Analysis of the data has shown that the risk factors of pain in the lower part of the spine do affect the absenteeism of city bus drivers.

National Driver Register (NDR) -

Data.gov (United States)

Department of Transportation — Information regarding individuals who have had their driver licenses revoked, suspended or otherwise denied for cause, or who have been convicted of certain traffic...

Influence of multiple global change drivers on terrestrial carbon storage

DEFF Research Database (Denmark)

Yue, Kai; Fornara, Dario A; Yang, Wanqin

2017-01-01

The interactive effects of multiple global change drivers on terrestrial carbon (C) storage remain poorly understood. Here, we synthesise data from 633 published studies to show how the interactive effects of multiple drivers are generally additive (i.e. not differing from the sum of their indivi......The interactive effects of multiple global change drivers on terrestrial carbon (C) storage remain poorly understood. Here, we synthesise data from 633 published studies to show how the interactive effects of multiple drivers are generally additive (i.e. not differing from the sum...... additive effects of multiple global change drivers into future assessments of the C storage ability of terrestrial ecosystems....

Driver ASICs for Advanced Deformable Mirrors, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The overall goal of the SBIR program is to develop a new Application Specified Integrated Circuit (ASIC) driver to be used in driver electronics of a deformable...

What the drivers do and do not tell you: using verbal protocol analysis to investigate driver behaviour in emergency situations.

Science.gov (United States)

Banks, Victoria A; Stanton, Neville A; Harvey, Catherine

2014-01-01

Although task analysis of pedestrian detection can provide us with useful insights into how a driver may behave in emergency situations, the cognitive elements of driver decision-making are less well understood. To assist in the design of future Advanced Driver Assistance Systems, such as Autonomous Emergency Brake systems, it is essential that the cognitive elements of the driving task are better understood. This paper uses verbal protocol analysis in an exploratory fashion to uncover the thought processes underlying behavioural outcomes represented by hard data collected using the Southampton University Driving Simulator.

Beginning teenage drivers

Science.gov (United States)

2010-01-01

Teen drivers have the highest crash risk of any age group. Per mile traveled, they have the highest involvement rates in all types of crashes, from those involving only property damage to those that are fatal. The problem is worst among 16 year-olds,...

49 CFR 383.51 - Disqualification of drivers.

Science.gov (United States)

2010-10-01

... parking violation) arising in connection with a fatal accident 60 days 60 days 120 days 120 days. (6... less than 120 days No less than 1 year. (4) The driver fails to have sufficient space to drive... driver fails to negotiate a crossing because of insufficient undercarriage clearance * * * No less than...

Does automatic transmission improve driving behavior in older drivers?

Science.gov (United States)

Selander, Helena; Bolin, Ingrid; Falkmer, Torbjörn

2012-01-01

Most older drivers continue to drive as they age. To maintain safe and independent transport, mobility is important for all individuals, but especially for older drivers. The objective of this study was to investigate whether automatic transmission, compared with manual transmission, may improve the driving behavior of older drivers. In total, 31 older drivers (mean age 75.2 years) and 32 younger drivers - used as a control group (mean age 39.2 years) - were assessed twice on the same fixed route; once in a car with manual transmission and once in a car with automatic transmission. The cars were otherwise identical. The driving behavior was assessed with the Ryd On-Road Assessment driving protocol. Time to completion of left turns (right-hand side driving) and the impact of a distraction task were measured. The older group had more driving errors than the younger group, in both the manual and the automatic transmission car. However, and contrary to the younger drivers, automatic transmission improved the older participants' driving behavior as demonstrated by safer speed adjustment in urban areas, greater maneuvering skills, safer lane position and driving in accordance with the speed regulations. Switching to automatic transmission may be recommended for older drivers as a means to maintain safe driving and thereby the quality of their transport mobility. Copyright © 2011 S. Karger AG, Basel.

Optical interconnects

CERN Document Server

Chen, Ray T

2006-01-01

This book describes fully embedded board level optical interconnect in detail including the fabrication of the thin-film VCSEL array, its characterization, thermal management, the fabrication of optical interconnection layer, and the integration of devices on a flexible waveguide film. All the optical components are buried within electrical PCB layers in a fully embedded board level optical interconnect. Therefore, we can save foot prints on the top real estate of the PCB and relieve packaging difficulty reduced by separating fabrication processes. To realize fully embedded board level optical

Evaluation of a program to enhance young drivers' safety in Israel.

Science.gov (United States)

Toledo, Tomer; Lotan, Tsippy; Taubman-Ben-Ari, Orit; Grimberg, Einat

2012-03-01

Young drivers in Israel, as in other parts of the world, are involved in car crashes more than any other age group. The graduated driver licensing system in Israel requires that all new drivers be accompanied by an experienced driver whenever they drive for the first 3 months after obtaining a driving license. In an effort to make the accompanied driving phase more effective, a novel program which targets both young drivers and their parents was initiated in 2005. The program administers a personal meeting with the young driver and the accompanying parent scheduled for the beginning of the accompanied driving phase. In this meeting guidance is given regarding best practices for undertaking the accompanied driving, as well as tips for dealing with in-vehicle parent-teen dynamics. Through 2008, almost 130,000 families of young drivers have participated in the program. In order to evaluate the effectiveness of the program, injury crash records of the young drivers who participated in the program were compared with those of all other young drivers that were licensed at the same time period. The results obtained indicate statistically significant lower crash records for young drivers that participated in the program. Limitations of the evaluation related to self-selection biases are discussed, and practical implications are suggested. Copyright © 2011 Elsevier Ltd. All rights reserved.

Multiple logistic regression model of signalling practices of drivers on urban highways

Science.gov (United States)

Puan, Othman Che; Ibrahim, Muttaka Na'iya; Zakaria, Rozana

2015-05-01

Giving signal is a way of informing other road users, especially to the conflicting drivers, the intention of a driver to change his/her movement course. Other users are exposed to hazard situation and risks of accident if the driver who changes his/her course failed to give signal as required. This paper describes the application of logistic regression model for the analysis of driver's signalling practices on multilane highways based on possible factors affecting driver's decision such as driver's gender, vehicle's type, vehicle's speed and traffic flow intensity. Data pertaining to the analysis of such factors were collected manually. More than 2000 drivers who have performed a lane changing manoeuvre while driving on two sections of multilane highways were observed. Finding from the study shows that relatively a large proportion of drivers failed to give any signals when changing lane. The result of the analysis indicates that although the proportion of the drivers who failed to provide signal prior to lane changing manoeuvre is high, the degree of compliances of the female drivers is better than the male drivers. A binary logistic model was developed to represent the probability of a driver to provide signal indication prior to lane changing manoeuvre. The model indicates that driver's gender, type of vehicle's driven, speed of vehicle and traffic volume influence the driver's decision to provide a signal indication prior to a lane changing manoeuvre on a multilane urban highway. In terms of types of vehicles driven, about 97% of motorcyclists failed to comply with the signal indication requirement. The proportion of non-compliance drivers under stable traffic flow conditions is much higher than when the flow is relatively heavy. This is consistent with the data which indicates a high degree of non-compliances when the average speed of the traffic stream is relatively high.

The Drivers of Success in Business Model Transformation

Directory of Open Access Journals (Sweden)

Nenad Savič

2016-01-01

Full Text Available Existing empirical literature on business models is still inconclusive about the key drivers of successful business model transformation. The paper explores this issue by using a single longitudinal case study design in combination with grounded theory approach on a medium-sized, high-tech and globally oriented company. Based on on-site visits, interviews and secondary documentation data analysis, the study identifies six generic drivers of successful business model transformation: transformational leadership, discovery driven decision-making, industry improvement – customer specific orientation, content-oriented communication, self-initiative collaborators, and phased separation strategy. The new drivers supplement our existing knowledge on how successful transformation takes place and add to existing drivers, while extensive discussion of their implications may help the managers to execute business transformations more effectively.

Rational-driver approximation in car-following theory

Science.gov (United States)

Lubashevsky, Ihor; Wagner, Peter; Mahnke, Reinhard

2003-11-01

The problem of a car following a lead car driven with constant velocity is considered. To derive the governing equations for the following car dynamics a cost functional is constructed. This functional ranks the outcomes of different driving strategies, which applies to fairly general properties of the driver behavior. Assuming rational-driver behavior, the existence of the Nash equilibrium is proved. Rational driving is defined by supposing that a driver corrects continuously the car motion to follow the optimal path minimizing the cost functional. The corresponding car-following dynamics is described quite generally by a boundary value problem based on the obtained extremal equations. Linearization of these equations around the stationary state results in a generalization of the widely used optimal velocity model. Under certain conditions (the “dense traffic” limit) the rational car dynamics comprises two stages, fast and slow. During the fast stage a driver eliminates the velocity difference between the cars, the subsequent slow stage optimizes the headway. In the dense traffic limit an effective Hamiltonian description is constructed. This allows a more detailed nonlinear analysis. Finally, the differences between rational and bounded rational driver behavior are discussed. The latter, in particular, justifies some basic assumptions used recently by the authors to construct a car-following model lying beyond the frameworks of rationality.

Free-piston driver performance characterisation using experimental shock speeds through helium

Science.gov (United States)

Gildfind, D. E.; James, C. M.; Morgan, R. G.

2015-03-01

Tuned free-piston driver operation involves configuring the driver to produce a relatively steady blast of driver gas over the critical time scales of the experiment. For the purposes of flow condition development and parametric studies, it is useful to establish some average working values of the driver pressure and temperature for a given driver operating condition. However, in practise, these averaged values need to produce sufficiently accurate estimates of performance. In this study, two tuned driver conditions in the X2 expansion tube have been used to generate shock waves through a helium test gas. The measured shock speeds have then been used to calculate the effective driver gas pressure and temperature after diaphragm rupture. Since the driver gas is typically helium, or a mixture of helium and argon, and the test gas is also helium, ideal gas assumptions can be made without significant loss of accuracy. The technique is applicable to tuned free-piston drivers with a simple area change, as well as those using orifice plates. It is shown that this technique can be quickly used to establish average working driver gas properties which produce very good estimates of actual driven shock speed, across a wide range of operating conditions. The use of orifice plates to control piston dynamics at high driver gas sound speeds is also discussed in the paper, and a simple technique for calculating the restriction required to modify an established safe condition for use with lighter gases, such as pure helium, is presented.

Chinese carless young drivers' self-reported driving behavior and simulated driving performance.

Science.gov (United States)

Zhang, Qian; Jiang, Zuhua; Zheng, Dongpeng; Man, Dong; Xu, Xunnan

2013-01-01

Carless young drivers refers to those drivers aged between 18 and 25 years who have a driver's license but seldom have opportunities to practice their driving skills because they do not have their own cars. Due to China's lower private car ownership, many young drivers become carless young drivers after licensure, and the safety issue associated with them has raised great concern in China. This study aims to provide initial insight into the self-reported driving behaviors and simulated driving performance of Chinese carless young drivers. Thirty-three carless young drivers and 32 young drivers with their own cars (as a comparison group) participated in this study. A modified Driver Behavior Questionnaire (DBQ) with a 4-factor structure (errors, violations, attention lapses, and memory lapses) was used to study carless young drivers' self-reported driving behaviors. A simulated driving experiment using a low-cost, fixed-base driving simulator was conducted to measure their simulated driving performance (errors, violations, attention lapses, driving maintenance, reaction time, and accidents). Self-reported DBQ outcomes showed that carless young drivers reported similar errors, more attention lapses, fewer memory lapses, and significantly fewer violation behaviors relative to young drivers with their own cars, whereas simulated driving results revealed that they committed significantly more errors, attention lapses, and violation behaviors than the comparison group. Carless young drivers had a lower ability to maintain the stability of speed and lane position, drove more cautiously approaching and passing through red traffic lights, and committed more accidents during simulated driving. A tendency to speed was not found among carless young drivers; their average speed and speeding frequency were all much lower than that of the comparison group. Lifetime mileage was the only significant predictor of carless young drivers' self-reported violations, simulated violations

Programmable cellular arrays. Faults testing and correcting in cellular arrays

International Nuclear Information System (INIS)

Cercel, L.

1978-03-01

A review of some recent researches about programmable cellular arrays in computing and digital processing of information systems is presented, and includes both combinational and sequential arrays, with full arbitrary behaviour, or which can realize better implementations of specialized blocks as: arithmetic units, counters, comparators, control systems, memory blocks, etc. Also, the paper presents applications of cellular arrays in microprogramming, in implementing of a specialized computer for matrix operations, in modeling of universal computing systems. The last section deals with problems of fault testing and correcting in cellular arrays. (author)

Solid state light source driver establishing buck or boost operation

Science.gov (United States)

Palmer, Fred

2017-08-29

A solid state light source driver circuit that operates in either a buck convertor or a boost convertor configuration is provided. The driver circuit includes a controller, a boost switch circuit and a buck switch circuit, each coupled to the controller, and a feedback circuit, coupled to the light source. The feedback circuit provides feedback to the controller, representing a DC output of the driver circuit. The controller controls the boost switch circuit and the buck switch circuit in response to the feedback signal, to regulate current to the light source. The controller places the driver circuit in its boost converter configuration when the DC output is less than a rectified AC voltage coupled to the driver circuit at an input node. The controller places the driver circuit in its buck converter configuration when the DC output is greater than the rectified AC voltage at the input node.

Obstacles to engaging in young driver licensing: Perspectives of parents.

Science.gov (United States)

Naz, Sehana; Scott-Parker, Bridie

2017-02-01

Young novice drivers remain at greater risk of injury and death despite a wealth of interventions including graduated driver licensing (GDL) programs. The key to implementing safer practices inherent in GDL appears to lie with optimising the role of parents. This qualitative research explored the parent's perspectives of obstacles to engaging in the driver licensing process within a GDL program. Parents also shared advice on what they found helpful, and where relevant, recommended changes in the process to enable safer practices for young drivers. Twenty-three parents (aged 35-60 years, M=49.52, SD=8.01, 11 males) participated in semi-structured interviews regarding licensing experiences with their young driver children. The young drivers included learner (n=11), provisional (restricted/intermediate) (n=9) and open (unrestricted/full) licence drivers (n=3), ranging from 16 to 24 years (M=18.04, SD=2.21, 13 males). Content analysis revealed that most obstacles were encountered at the learner licensing phase, with the parent-reported difficult temperament of the learner driver the most prominent. Unsurprisingly, advice to other parents to be patient and remain calm featured heavily during the same phase. Anxiety from not having control of the vehicle was another obstacle at the learner phase, translating to anxieties for child safety in the early stages of provisional driving. Recommendations for the current GDL included more rigorous road rule testing, with general support for the program, professional driver training at learner and provisional stages facilitated parental engagement through the licensing phases. The findings overwhelmingly suggest a need for parents to be educated regarding their importance in, and of, the driver licensing process, and the efficacy of their instruction, content and practices. Copyright © 2016 Elsevier Ltd. All rights reserved.

Study on driver model for hybrid truck based on driving simulator experimental results

Directory of Open Access Journals (Sweden)

Dam Hoang Phuc

2018-04-01

Full Text Available In this paper, a proposed car-following driver model taking into account some features of both the compensatory and anticipatory model representing the human pedal operation has been verified by driving simulator experiments with several real drivers. The comparison between computer simulations performed by determined model parameters with the experimental results confirm the correctness of this mathematical driver model and identified model parameters. Then the driver model is joined to a hybrid vehicle dynamics model and the moderate car following maneuver simulations with various driver parameters are conducted to investigate influences of driver parameters on vehicle dynamics response and fuel economy. Finally, major driver parameters involved in the longitudinal control of drivers are clarified. Keywords: Driver model, Driver-vehicle closed-loop system, Car Following, Driving simulator/hybrid electric vehicle (B1

The Effect of Passengers on Teen Driver Behavior

Science.gov (United States)

2012-04-01

A number of studies have shown that passengers substantially increase the risk of crashes for young, novice drivers. This increased risk may result from distractions that young passengers create for drivers. Alternatively, the presence of passengers ...

Using Shadow Page Cache to Improve Isolated Drivers Performance

Directory of Open Access Journals (Sweden)

Hao Zheng

2015-01-01

Full Text Available With the advantage of the reusability property of the virtualization technology, users can reuse various types and versions of existing operating systems and drivers in a virtual machine, so as to customize their application environment. In order to prevent users’ virtualization environments being impacted by driver faults in virtual machine, Chariot examines the correctness of driver’s write operations by the method of combining a driver’s write operation capture and a driver’s private access control table. However, this method needs to keep the write permission of shadow page table as read-only, so as to capture isolated driver’s write operations through page faults, which adversely affect the performance of the driver. Based on delaying setting frequently used shadow pages’ write permissions to read-only, this paper proposes an algorithm using shadow page cache to improve the performance of isolated drivers and carefully study the relationship between the performance of drivers and the size of shadow page cache. Experimental results show that, through the shadow page cache, the performance of isolated drivers can be greatly improved without impacting Chariot’s reliability too much.

Parent attitudes toward integrating parent involvement into teenage driver education courses.

Science.gov (United States)

Hartos, Jessica; Huff, David C

2008-01-01

The widespread adoption of graduated driver licensing (GDL) policies has effectively reduced crash risk for young drivers; however, parents must support, reinforce, and enforce GDL for it to be effective, and research indicates that parents need better information and instruction for adhering to GDL requirements, conducting supervised practice driving, and restricting independent teenage driving. Because teenagers in most states must take driver education to enter the licensing process prior to age 18, integrating parent involvement into driver education may be an effective way to inform and instruct parents on a large scale about teen driver safety. This study assessed parent attitudes (overall and by rural status, minority status, and income level) toward integrating parent involvement into teenage driver education classes. In this study, 321 parents of teenagers enrolled in driver education classes across the state of Montana completed surveys about current involvement in driver education and attitudes toward required involvement. The results indicated that parents were not very involved currently in their teenagers' driver education classes, but 76% reported that parents should be required to be involved. If involvement were required, parents would prefer having written materials sent home, access to information over the Internet, or discussions in person with the instructor; far fewer would prefer to attend classes or behind-the-wheel driving instruction. There were few differences in parent attitudes by rural or minority status but many by income level. Compared to higher income parents, lower income parents were more likely to endorse required parent involvement in teenage driver education classes and to want parent information from driver education about many teen driving issues. That the majority of parents are open to required involvement in their teenagers' driver education classes is promising because doing so could better prepare parents to understand

Truck Drivers' Use of the Internet: A Mobile Health Lifeline.

Science.gov (United States)

Heaton, Karen; Combs, Bryan; Griffin, Russell

2017-06-01

Because of their social isolation, irregular and unpredictable schedules, limited access to health care, and long periods of travel, long-haul truckers may benefit from the use of mobile health applications on Internet-capable devices. The purpose of this study was to determine Internet access and usage among a sample of long-haul truck drivers. In this cross-sectional study, truck drivers completed a pencil and paper survey with questions on demographics, work and health histories, and Internet access and usage for both personal and job reasons. A total of 106 truck drivers were recruited from trucking industry trade shows, by word of mouth, and directly from trucking companies. Overall, the truck drivers' use of the Internet was limited. Their usage for personal and job-related reasons differed. Social connectivity and access to health and wellness information were important during personal usage time. Job-related Internet use was highly practical, and applied to seeking information for directions and maps, fuel stops and pricing, and communicating with employers or transmitting documents. Age and experience were associated with Internet use. Younger, less-experienced drivers used the Internet more than older, experienced drivers. Targeted mobile health messaging may be a useful tool to inform truck drivers of health conditions and plans, and may provide links to primary care providers needing to monitor or notify drivers of diagnostic results or treatment plans.

Improving drivers' knowledge of road rules using digital games.

Science.gov (United States)

Li, Qing; Tay, Richard

2014-04-01

Although a proficient knowledge of the road rules is important to safe driving, many drivers do not retain the knowledge acquired after they have obtained their licenses. Hence, more innovative and appealing methods are needed to improve drivers' knowledge of the road rules. This study examines the effect of game based learning on drivers' knowledge acquisition and retention. We find that playing an entertaining game that is designed to impart knowledge of the road rules not only improves players' knowledge but also helps them retain such knowledge. Hence, learning by gaming appears to be a promising learning approach for driver education. Copyright © 2013 Elsevier Ltd. All rights reserved.

Investigating the impact of static roadside advertising on drivers' situation awareness.

Science.gov (United States)

Young, Kristie L; Stephens, Amanda N; Logan, David B; Lenné, Michael G

2017-04-01

Roadside advertising has the potential to create a crash risk for drivers as it may distract attention from driving at critical times. In an on-road instrumented vehicle study, we examined if and how static advertising billboards affect drivers' situation awareness across different driving environments. Nineteen fully licensed drivers drove an instrumented vehicle around a 38 km urban test route comprising freeway, busy urban retail and arterial road sections. The route contained a number of static billboards. Drivers provided continuous verbal protocols throughout the drive. Results indicated that the structure and content of drivers' situation awareness was not appreciably affected by the billboards in any of the road environments examined. Drivers focused their attention on the billboards when driving demand was low, such as when driving on the freeway with light to moderate traffic, in lower speed zones, or when stationary. However, when drivers were required to perform a manoeuvre or driving demands increased, drivers directed less attention to the billboards and focussed their awareness on the immediate driving task. This suggests that drivers can, at least under some conditions, effectively self-regulate their attention to billboards when required to focus on the immediate traffic or driving situation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quantitative analysis of the relationship between driver`s behavior and vehicle motion; Sharyo unten ni taisuru untensha no kyodo no teiryoka bunseki ni tsuite

Energy Technology Data Exchange (ETDEWEB)

Nakagawa, H; Matsuura, Y [Osaka Sangyo University, Osaka (Japan); Masuda, T

1997-10-01

In order to study the subject of driving safety about the human-vehicle interaction, driver`s maneuvering behavior was shot by CCD-cameras installed in a cabin and the motion of traveling vehicle was simultaneously taken by VTR-cameras set on the test course. These pictures were analyzed using the three-dimensional image processing system (Peak Motus system). Consequently, this system was effectively able to use for these measurements and analysis and introduced the correlation between the vehicle movement and the driver`s action. 4 refs., 12 figs., 2 tabs.

About Assessment Criteria of Driver's Accidental Abilities

Science.gov (United States)

Lobanova, Yuliya I.; Glushko, Kirill V.

2016-01-01

The article points at the importance of studying the human factor as a cause of accidents of drivers, especially in loosely structured traffic situations. The description of the experiment on the measurement of driver's accidental abilities is given. Under accidental ability is meant the capability to ensure the security of driving as a behavior…

SmartDriver for school bus : participant's handbook

International Nuclear Information System (INIS)

2007-01-01

SmartDriver is a key component of Natural Resources Canada's ecoENERGY for fleets program. The aim of the ecoENERGY initiative is to introduce fleets to energy-efficient practices for reducing fuel consumption and emissions and to help drivers adopt the driving practices outlined in the SmartDriver training materials. The handbook was designed as part of a comprehensive media package that included a CD-ROM with audio-visual components. The package was developed as a training strategy for fuel-efficient driving skills. The first module contained information on air pollution and techniques that drivers can adopt to reduce particulate matter, smog, greenhouse gas (GHG) emissions. An outline of new engine technologies developed to reduce emissions was also provided. The second module discussed various vehicle factors that influence fuel efficiency. Alternative fuels were reviewed, and vehicle components were discussed in relation to improving fuel economy. The module also included preventive maintenance tips as well as engine starting techniques and methods for reducing time spent idling. Various activities and games related to improving fuel efficiency were also included. 17 figs

An Overview on Study of Identification of Driver Behavior Characteristics for Automotive Control

Directory of Open Access Journals (Sweden)

Na Lin

2014-01-01

Full Text Available Driver characteristics have been the research focus for automotive control. Study on identification of driver characteristics is provided in this paper in terms of its relevant research directions and key technologies involved. This paper discusses the driver characteristics based on driver’s operation behavior, or the driver behavior characteristics. Following the presentation of the fundamental of the driver behavior characteristics, the key technologies of the driver behavior characteristics are reviewed in detail, including classification and identification methods of the driver behavior characteristics, experimental design and data acquisition, and model adaptation. Moreover, this paper discusses applications of the identification of the driver behavior characteristics which has been applied to the intelligent driver advisory system, the driver safety warning system, and the vehicle dynamics control system. At last, some ideas about the future work are concluded.

UWB dual burst transmit driver

Science.gov (United States)

Dallum, Gregory E [Livermore, CA; Pratt, Garth C [Discovery Bay, CA; Haugen, Peter C [Livermore, CA; Zumstein, James M [Livermore, CA; Vigars, Mark L [Livermore, CA; Romero, Carlos E [Livermore, CA

2012-04-17

A dual burst transmitter for ultra-wideband (UWB) communication systems generates a pair of precisely spaced RF bursts from a single trigger event. An input trigger pulse produces two oscillator trigger pulses, an initial pulse and a delayed pulse, in a dual trigger generator. The two oscillator trigger pulses drive a gated RF burst (power output) oscillator. A bias driver circuit gates the RF output oscillator on and off and sets the RF burst packet width. The bias driver also level shifts the drive signal to the level that is required for the RF output device.

Do advertisements at the roadside distract the driver?

Science.gov (United States)

Kettwich, Carmen; Klinger, Karsten; Lemmer, Uli

2008-04-01

Nowadays drivers have to get along with an increasing complex visual environment. More and more cars are on the road. There are not only distractions available within the vehicle, like radio and navigation system, the environment outside the car has also become more and more complex. Hoardings, advertising pillars, shop fronts and video screens are just a few examples. For this reason the potential risk of driver distraction is rising. But in which way do the advertisements at the roadside influence the driver's attention? The investigation which is described is devoted to this topic. Various kinds of advertisements played an important role, like illuminated and non-illuminated posters as well as illuminated animated ads. Several test runs in an urban environment were performed. The gaze direction of the driver's eye was measured with an eye tracking system. The latter consists of three cameras which logged the eye movements during the test run and a small-sized scene camera recording the traffic scene. 16 subjects (six female and ten male) between 21 and 65 years of age took part in this experiment. Thus the driver's fixation duration of the different advertisements could be determined.

ISAF'S Afghan Truck Drivers: The Overlooked Counterinsurgency Population

Directory of Open Access Journals (Sweden)

Myron Varouhakis

2015-12-01

Full Text Available A yearlong U.S. Army field study in Afghanistan examined the demographics and threat perceptions of one of the most-at-risk populations, that of Afghan truck drivers working for NATO’s International Security Assistance Force Afghanistan (ISAF. The study collected data from 766 Afghan truck drivers at the U.S.-operated Kandahar Airfield in ISAF’s Regional Command South. The findings show a wide diversity in age of the Afghan drivers as well as in terms of their home province. The findings also show that although all Afghan truck drivers had acute awareness and understanding of the high risks and dangers of the job, they all noted that the attractive salary and scarcity of jobs were dominant reasons for staying on the job. Findings also reveal a strong resentment among the Afghan truck drivers about their treatment by ISAF soldiers, as for the lack of protection for them and their families after the 2014 departure of NATO forces. The findings can provide significant insights and enhance the understanding of scholars, counterinsurgency strategists, policymakers, and military planners about “Host Country Nationals” as an important population of the human terrain.

Continuous traffic flow modeling of driver support systems in multiclass traffic with inter-vehicle communication and drivers in the loop

NARCIS (Netherlands)

Tampere, C.M.J.; Hoogendoorn, S.P.; Arem, B. van

2009-01-01

This paper presents a continuous traffic-flow model for the explorative analysis of advanced driver-assistance systems (ADASs). Such systems use technology (sensors and intervehicle communication) to support the task of the driver, who retains full control over the vehicle. Based on a review of

Driver education practices in selected states : traffic tech.

Science.gov (United States)

2011-07-01

Teen drivers have the highest crash rate per mile driven of any : age group (Williams, Ferguson, & Wells, 2005). Immaturity and : inexperience are two explanations for why novice teen drivers : have such a high crash risk (Arnett, 1992; Mayhew, Simps...

Methodology to evaluate teen driver training programs : [brief].

Science.gov (United States)

2014-03-01

In the United States, teenage drivers are more at risk of being involved in crashes than : any other age group. Statistics reveal a clear need for improving teenagers driving : skills, judgment and behavior. Driver education programs are a crucial...

Physics at an upgraded Fermilab proton driver

Energy Technology Data Exchange (ETDEWEB)

Geer, S.; /Fermilab

2005-07-01

In 2004 the Fermilab Long Range Planning Committee identified a new high intensity Proton Driver as an attractive option for the future, primarily motivated by the recent exciting developments in neutrino physics. Over the last few months a physics study has developed the physics case for the Fermilab Proton Driver. The potential physics opportunities are discussed.

Prevalence of Psychoactive Drug Use by Taxi Drivers in Nigeria ...

African Journals Online (AJOL)

Aim: To ascertain the prevalence and nature of psychoactive drug use amongst taxi drivers in Nigeria. Materials and Method: A total of 192 taxi drivers in Enugu, South East Nigeria was studied using a questionnaire. Information obtained from the questionnaire included socio-demographic characteristics of the drivers, ...

49 CFR 604.8 - Leasing FTA funded equipment and drivers.

Science.gov (United States)

2010-10-01

... 49 Transportation 7 2010-10-01 2010-10-01 false Leasing FTA funded equipment and drivers. 604.8... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CHARTER SERVICE Exceptions § 604.8 Leasing FTA funded equipment and drivers. (a) A recipient may lease its FTA-funded equipment and drivers to registered charter providers...

GPS Usage in a Population of Low-Vision Drivers.

Science.gov (United States)

Cucuras, Maria; Chun, Robert; Lee, Patrick; Jay, Walter M; Pusateri, Gregg

2017-01-01

We surveyed bioptic and non-bioptic low-vision drivers in Illinois, USA, to determine their usage of global positioning system (GPS) devices. Low-vision patients completed an IRB-approved phone survey regarding driving demographics and usage of GPS while driving. Participants were required to be active drivers with an Illinois driver's license, and met one of the following criteria: best-corrected visual acuity (BCVA) less than or equal to 20/40, central or significant peripheral visual field defects, or a combination of both. Of 27 low-vision drivers, 10 (37%) used GPS while driving. The average age for GPS users was 54.3 and for non-users was 77.6. All 10 drivers who used GPS while driving reported increased comfort or safety level. Since non-GPS users were significantly older than GPS users, it is likely that older participants would benefit from GPS technology training from their low-vision eye care professionals.

Research on Taxi Driver Strategy Game Evolution with Carpooling Detour

Directory of Open Access Journals (Sweden)

Wei Zhang

2018-01-01

Full Text Available For the problem of taxi carpooling detour, this paper studies driver strategy choice with carpooling detour. The model of taxi driver strategy evolution with carpooling detour is built based on prospect theory and evolution game theory. Driver stable strategies are analyzed under the conditions of complaint mechanism and absence of mechanism, respectively. The results show that passenger’s complaint mechanism can effectively decrease the phenomenon of driver refusing passengers with carpooling detour. When probability of passenger complaint reaches a certain level, the stable strategy of driver is to take carpooling detour passengers. Meanwhile, limiting detour distance and easing traffic congestion can decrease the possibility of refusing passengers. These conclusions have a certain guiding significance to formulating taxi policy.

Knowledge of commercial bus drivers about road safety measures in Lagos, Nigeria.

Science.gov (United States)

Okafor Ifeoma, P; Odeyemi Kofoworola, A; Dolapo Duro, C

2013-01-01

Road traffic injuries have persisted as a serious public health problem and much of the health burden is in developing countries. Over-speeding, poor enforcement of traffic regulations and commuter buses have been highly implicated in road traffic injuries in developing countries. The aim of this study was to determine drivers' knowledge of selected road safety measures, i.e. the pre-requisites for driver's license, road signs and speed limits. This was a cross-sectional study carried out in Lagos, Nigeria. Simple random sampling was used to select the two motor parks used for the study and all the consenting commercial minibus drivers operating within the parks (407) were included in the study. Data was collected with a pre-tested, structured, interviewer-administered questionnaire and analyzed with epi-info statistical software. Two hundred and sixty-one (64.1%) of them knew that Visual Acuity test should be done before obtaining driver's license and 53.8% knew the correct minimum age for obtaining driver's license. Only 1% of the drivers had correct knowledge of the driver's license authorities in Nigeria. The drivers had poor knowledge of road signs (59.0%) and poor knowledge of maximum speed limits (100%). The oldest, least educated and least experienced drivers had the poorest level of knowledge. The drivers demonstrated poor knowledge of road safety measures. There is need for driver education to improve their knowledge.

Linear transformer driver for pulse generation

Science.gov (United States)

Kim, Alexander A; Mazarakis, Michael G; Sinebryukhov, Vadim A; Volkov, Sergey N; Kondratiev, Sergey S; Alexeenko, Vitaly M; Bayol, Frederic; Demol, Gauthier; Stygar, William A

2015-04-07

A linear transformer driver includes at least one ferrite ring positioned to accept a load. The linear transformer driver also includes a first power delivery module that includes a first charge storage devices and a first switch. The first power delivery module sends a first energy in the form of a first pulse to the load. The linear transformer driver also includes a second power delivery module including a second charge storage device and a second switch. The second power delivery module sends a second energy in the form of a second pulse to the load. The second pulse has a frequency that is approximately three times the frequency of the first pulse. The at least one ferrite ring is positioned to force the first pulse and the second pulse to the load by temporarily isolating the first pulse and the second pulse from an electrical ground.

Design and simulation of advanced charge recovery piezoactuator drivers

International Nuclear Information System (INIS)

Biancuzzi, G; Lemke, T; Woias, P; Goldschmidtboeing, F; Ruthmann, O; Schrag, H J; Vodermayer, B; Schmid, T

2010-01-01

The German Artificial Sphincter System project aims at the development of an implantable sphincter prosthesis driven by a piezoelectrically actuated micropump. The system has been designed to be fully implantable, i.e. the power supply is provided by a rechargeable lithium polymer battery. In order to provide sufficient battery duration and to limit battery dimensions, special effort has to be made to minimize power consumption of the whole system and, in particular, of the piezoactuator driver circuitry. Inductive charge recovery can be used to recover part of the charge stored within the actuator. We are going to present a simplified inductor-based circuit capable of voltage inversion across the actuator without the need of an additional negative voltage source. The dimension of the inductors required for such a concept is nevertheless significant. We therefore present a novel alternative concept, called direct switching, where the equivalent capacitance of the actuator is charged directly by a step-up converter and discharged by a step-down converter. We achieved superior performance compared to a simple inductor-based driver with the advantage of using small-size chip inductors. As a term of comparison, the performance of the aforementioned drivers is compared to a conventional driver that does not implement any charge recovery technique. With our design we have been able to achieve more than 50% reduction in power consumption compared to the simplest conventional driver. The new direct switching driver performs 15% better than an inductor-based driver. A novel, whole-system SPICE simulation is presented, where both the driving circuit and the piezoactuator are modeled making use of advanced nonlinear models. Such a simulation is a precious tool to design and optimize piezoactuator drivers

Gaze position modulates the effectiveness of forward collision warnings for drowsy drivers.

Science.gov (United States)

Gaspar, John G; Schwarz, John-Chris W; Brown, Timothy L; Kang, Julie

2017-12-22

Advanced driver assistance systems (ADAS) have the potential to prevent crashes and reduce their severity. Forward collision warnings (FCW) are quickly becoming standard across vehicle lineups and may prevent frontal crashes by alerting drivers. Previous research has demonstrated the effectiveness of FCW for distracted drivers, but their effectiveness for other types of impairment remains unknown. Like distraction, drowsiness can impair driver response time and lead to crashes. The goal of the present study was to evaluate the effectiveness of FCW for moderately and severely drowsy drivers using a high-fidelity driving simulator. Drowsy drivers were divided into three warning conditions during a revealed stop vehicle forward collision event: An auditory alert, a haptic seat vibration, and a no warning baseline. Results indicate that FCW were effective at speeding drowsy driver response, but only when the drowsy drivers were looking away from the forward roadway at the onset of the event. These results have important implications for ADAS technology and driver state monitoring systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

An assessment of deforestation and forest degradation drivers in developing countries

International Nuclear Information System (INIS)