Modelling of ratchetting

International Nuclear Information System (INIS)

Geyer, P.; Proix, J.M.; Shoenberger, P.; Taheri, S.

1993-09-01

The normal or abnormal operating subjects the nuclear power plant's components to cyclic loading (pressure, temperature gradient). So, we can have a progressive strain accumulation on every cyclic loading. This ratchet (cyclic strain accumulation) can produce excessive deformation or increase some damages as thermal fatigue. For some components, a fine modelling of the material's behaviour is necessary to study their mechanical strength. The modelling of cyclic plasticity made great progress during the past 20 years. The ratchet is one of the last phenomena for which numerical models have to be improved. We give in this paper the present state of research to model the description of ratcheting effects. Then we use the experimental results on the austenitic stainless steel 316L at 20 deg C and 300 deg C to study the TAHERI and the BURLET and CAILLETAUD model's capabilities. The cyclic constitutive law with a discrete memory variable developed by TAHERI leads to a satisfying description of ratcheting phenomena in uniaxial loadings. With the modification of kinematic hardening proposed by Burlet and Cailletaud in the Chaboche model we get a good modelling of ratchet in biaxial loadings. These two models have been integrated into a 3D structural mechanics software, the F.E. code ASTER. We present here the calculation of a tubular structure with a thickness transition subjected to thermal cycling. (authors). 11 figs., 3 tabs., 22 refs

Molecular wires acting as quantum heat ratchets

OpenAIRE

Zhan, Fei; Li, Nianbei; Kohler, Sigmund; Hänggi, Peter

2009-01-01

We explore heat transfer in molecular junctions between two leads in the absence of a finite net thermal bias. The application of an unbiased, time-periodic temperature modulation of the leads entails a dynamical breaking of reflection symmetry, such that a directed heat current may emerge (ratchet effect). In particular, we consider two cases of adiabatically slow driving, namely (i) periodic temperature modulation of only one lead and (ii) temperature modulation of both leads with an ac dri...

Experimental quantum ratchets based on solid state nanostructures

International Nuclear Information System (INIS)

Linke, H.

1999-01-01

Ratchets are spatially asymmetric devices in which particles can move on average in one direction in the absence of external net forces or gradients. This is made possible by the rectification of fluctuations, which also provide the energy for the process. Interest in the physics of ratchets was revived in recent years when it emerged that the ratchet principle may be a suitable physical model for 'molecular motors', which are central to many fundamental biological processes, such as intracellular transport or muscle contraction. Most ratchets studied so far have relied on classical effects, but recently 'quantum ratchets', involving quantum effects, have also been studied. In the present article it is pointed out that semiconductor or metal nanostructures are very suitable systems for the realisation of experimental quantum ratchets. Recent experimental studies of a quantum ratchet based on an asymmetric quantum dot are reviewed. Copyright (1999) CSIRO Australia

Experimental quantum ratchets based on nanostructures

International Nuclear Information System (INIS)

Linke, H.; Loefgren, A.; Sheng, W.; Xu, H.; Svensson, A.; Omling, P.; Lindelof, P.E.

1999-01-01

Full text: A number of biological processes, for instance muscular contraction and intracellular transport, are based on a fascinating physical principle: In periodic, asymmetric potentials, so-called ratchets, the random motion of Brownian particles can be put to use by extracting energy from nonequilibrium fluctuations. These findings have recently revived interest in physics to explore the general principles of ratchet effects. So far, most ratchet systems studied assumed or used classical systems. In extension of this previous work, highly interesting and new physics can also be expected from ratchet mechanisms that rely on quantum processes. In this contribution, the requirements for experimental studies of quantum ratchet effects will be discussed, and it will be pointed out that these prerequisites are ideally fulfilled in semiconductor- and metal-nanostructures. As an example, experimental and theoretical results will be presented showing that phase-coherent, asymmetric (triangular) electron cavities can partially rectify an applied AC voltage. Using this effect, which is related to electron wave interference, an electron current can be generated without applied net field

Design methods for structures under thermal ratchet

International Nuclear Information System (INIS)

Branca, T.R.; McLean, J.L.

1975-01-01

Previous work on the thermal ratchet analysis of a simple pipe is extended to the case of an intersection of a pipe with a spherical shell. The chosen nozzle configuration is subjected to an internal pressure which remains constant, and a cyclic thermal transient which is representative of the type of transient that might be expected for components of a LMFBR. A number of cross-sections through the nozzle were examined, each yielding a different combination of elastic primary and secondary stress. These stresses, together with their associated cyclic strain growth, as determined from an elastic-plastic-creep analysis of the nozzle, were then plotted on a Miller or Bree-type diagram. Thus, a number of points, one for each cross-section considered, were available for comparison with the data obtained from the ratchet analysis of simple pipe sections. Both the elastic and inelastic analyses on the nozzle were performed using the finite element method of structural analysis of the ANSYS computer code. The pipe ratchetting cases were computed using the Oak Ridge National Laboratory PLACRE code. For a simple pipe ratchet case, a brief comparison is given between the version of ANSYS used in this study, the ANSYS version used in previous work and PLACRE code. The three programs did not yield identical results. Further study is needed to resolve the discrepancies that were observed. The results of the comparison between the nozzle ratchet and pipe ratchet solutions indicate that reasonable predictions can be made for the nozzle ratchet strains based on elastic parameters and design curves developed from pipe ratchetting solutions. (author)

Electrodynamic ratchet motor.

Science.gov (United States)

Lim, Jiufu; Sader, John E; Mulvaney, Paul

2009-03-01

Brownian ratchets produce directed motion through rectification of thermal fluctuations and have been used for separation processes and colloidal transport. We propose a flashing ratchet motor that enables the transduction of electrical energy into rotary micromechanical work. This is achieved through torque generation provided by boundary shaping of equipotential surfaces. The present device contrasts to previous implementations that focus on translational motion. Stochastic simulations elucidate the performance characteristics of this device as a function of its geometry. Miniaturization to nanoscale dimensions yields rotational speeds in excess of 1 kHz, which is comparable to biomolecular motors of similar size.

Uniaxial ratcheting behavior of Zircaloy-4 tubes at room temperature

International Nuclear Information System (INIS)

Wen, Mingjian; Li, Hua; Yu, Dunji; Chen, Gang; Chen, Xu

2013-01-01

In this study, a series of uniaxial tensile, strain cycling and uniaxial ratcheting tests were conducted at room temperature on Zircaloy-4 (Zr-4) tubes used as nuclear fuel cladding in Pressurized Water Reactors (PWRs) for the purpose to investigate the uniaxial ratcheting behavior of Zr-4 and the factors which may influence it. The experimental results show that at room temperature this material features cyclic softening remarkably within the strain range of 1.6%, and former cycling under larger strain amplitude cannot retard cyclic softening of later cycling under lower strain amplitude. Uniaxial ratcheting strain accumulates in the direction of mean stress, and the ratcheting stain level is larger under tensile mean stress than that under compressive mean stress. Uniaxial ratcheting strain level increases with the increase of mean stress and stress amplitude, and decreases with the increase of loading rate. The sequence of loading rate appears to have no effects on the final ratcheting strain accumulation. Loading history has great influence on the uniaxial ratcheting behavior. Lower stress level after loading history with higher stress level leads to the shakedown of ratcheting. Higher loading rate after loading history with lower loading rate brings down the ratcheting strain rate. Uniaxial ratcheting behavior is sensitive to compressive pre-strain, and the decay rate of the ratcheting strain rate is slowed down by pre-compression

Quantum ratchets reroute electrons

International Nuclear Information System (INIS)

Haenggi, P.; Reimann, P.

1999-01-01

Is it possible to extract energy from random fluctuations and put it to use? This challenging question has provoked discussion ever since the early days of Brownian-motion theory. For large-scale or macroscopic fluctuations, the answer is ''yes'' - the principle is demonstrated, for example, in the self-winding wristwatch. Much subtler is the issue of whether microscopic random fluctuations, such as thermal Brownian motion or even the haphazard motion of quantum particles, acting as a random energy source can cause the particles to flow in one direction only. In recent years this field has been the scene of remarkable activity, motivated by the prospect of potentially high-profile technological and biological applications, such as molecular motors. In particular the directed transport of particles in an asymmetric potential known as a ratchet has received a lot of attention. This research, however, has focused on ''thermal ratchets'' in which the particles undergo thermal Brownian motion: the next challenge is to move from the classical world and account for quantum mechanical effects. Recently a collaboration between physicists at Lund University in Sweden and the Niels Bohr Institute in Copenhagen has taken a significant step forward and built a quantum ratchet (H Linke et al. 1998 Europhys. Lett. 44 341 and 45 406). The device is based on an aluminium-doped gallium arsenide (GaAs/AlGaAs) quantum dot with a ratchet-like, triangular-shaped cavity. In this article the authors discuss the implications of this work. (UK)

Giant transversal particle diffusion in a longitudinal magnetic ratchet.

Science.gov (United States)

Tierno, Pietro; Reimann, Peter; Johansen, Tom H; Sagués, Francesc

2010-12-03

We study the transversal motion of paramagnetic particles on a uniaxial garnet film, exhibiting a longitudinal ratchet effect in the presence of an oscillating magnetic field. Without the field, the thermal diffusion coefficient obtained by video microscopy is D(0) ≈ 3 × 10(-4)  μm2/s. With the field, the transversal diffusion exhibits a giant enhancement by almost four decades and a pronounced maximum as a function of the driving frequency. We explain the experimental findings with a theoretical interpretation in terms of random disorder effects within the magnetic film.

Investigations into the ratchetting behaviour of austenitic pipes

International Nuclear Information System (INIS)

Kraemer, D.; Krolop, S.; Scheffold, A.; Stegmeyer, R.

1997-01-01

In technical components subjected to cyclic loading, inelastic deformations cannot be excluded. In such cases, under certain conditions, small amounts of non-reversed plastic strain per cycle can accumulate to large strains, an effect commonly called ratchetting. The proof of ratchetting in complex structures is often possible by numerical methods only, e.g. the finite-element method. Describing cyclic plasticity and predicting ratchetting necessitate a suitable constitutive law. This paper describes the investigation of the ratchetting behaviour of thin-walled tubes under cyclic loading. Tests were performed and accompanied by finite-element computations using a non-linear kinematic hardening rule with superposed isotropic cyclic hardening. The constitutive law applied used a set of 13 material parameters. This paper discusses the requirements for uniaxial tests which meet the determination of a suitable set of parameters for describing ratchetting. To describe different kinds of isotropic hardening, an extension of the isotropic hardening rule is proposed. Under uniaxial conditions, continuous cyclic hardening is well reproduced with this extension. (orig.)

Modeling of uniaxial ratchetting behavior of SA333 carbon manganese steel

International Nuclear Information System (INIS)

Shit, J.; Dhar, S.; Acharyya, S.K.; Goyal, S.

2012-01-01

The paper deals with uniaxial ratcheting phenomenon of cyclic plasticity behavior of the materials SA333 carbon Manganese steel. A mechanistic model for the ratcheting phenomenon has been proposed. It is observed that von Mises yield criterion together with Chaboche’s kinematic hardening rules are not sufficient to model ratcheting phenomenon. Other associated phenomena like plastic strain memory surface, back stress memory points and over all the extra hardening behavior have to be incorporated to get a complete material model for ratcheting. The proposed model assembled all these ideas together with von Mises yield criterion and Chabache’s kinematic hardening rule. Low cycle fatigue tests and uniaxial ratcheting tests have been conducted for the materials. The material constants are identified and derived from experimental results. The ratcheting coefficients have been properly calibrated with these material constants. The material model, as mentioned above, for the ratcheting phenomenon has been implemented in an elastic plastic finite element code. The ratcheting results for different stress controlled ratcheting loads have been computed. The good feature of this model is that it reduces to symmetric low cycle fatigue model when loop closes. - Highlights: ► A common material model to simulate symmetric LCF and ratcheting. ► Extra hardening to take care the shift of plastic strain centre. ► Material parameters from tensile and LCF tests. ► Saturated loop in LCF and ratcheting strain rate is compared with experiment. ► Consideration of loading path, memory path and their directions.

ASME code and ratcheting in piping components. Final technical report

International Nuclear Information System (INIS)

Hassan, T.; Matzen, V.C.

1999-01-01

The main objective of this research is to develop an analysis program which can accurately simulate ratcheting in piping components subjected to seismic or other cyclic loads. Ratcheting is defined as the accumulation of deformation in structures and materials with cycles. This phenomenon has been demonstrated to cause failure to piping components (known as ratcheting-fatigue failure) and is yet to be understood clearly. The design and analysis methods in the ASME Boiler and Pressure Vessel Code for ratcheting of piping components are not well accepted by the practicing engineering community. This research project attempts to understand the ratcheting-fatigue failure mechanisms and improve analysis methods for ratcheting predictions. In the first step a state-of-the-art testing facility is developed for quasi-static cyclic and seismic testing of straight and elbow piping components. A systematic testing program to study ratcheting is developed. Some tests have already been performed and the rest will be completed by summer'99. Significant progress has been made in the area of constitutive modeling. A number of sophisticated constitutive models have been evaluated in terms of their simulations for a broad class of ratcheting responses. From the knowledge gained from this evaluation study two improved models are developed. These models are demonstrated to have promise in simulating ratcheting responses in piping components. Hence, implementation of these improved models in widely used finite element programs, ANSYS and/or ABAQUS, is in progress. Upon achieving improved finite element programs for simulation of ratcheting, the ASME Code provisions for ratcheting of piping components will be reviewed and more rational methods will be suggested. Also, simplified analysis methods will be developed for operability studies of piping components and systems. Some of the future works will be performed under the auspices of the Center for Nuclear Power Plant Structures

High temperature viscoplastic ratchetting: Material response or modeling artifact

International Nuclear Information System (INIS)

Freed, A.D.

1991-01-01

Ratchetting, the net accumulation of strain over a loading cycle, is a deformation mechanism that leads to distortions in shape, often resulting in a loss of function that culminates in structural failure. Viscoplastic ratchetting is prevalent at high homologous temperatures where viscous characteristics are prominent in material response. This deformation mechanism is accentuated by the presence of a mean stress; a consequence of interaction between thermal gradients and structural constraints. Favorable conditions for viscoplastic ratchetting exist in the Stirling engines being developed by the National Aeronautics and Space Administration (NASA) and the Department of Energy (DOE) for space and terrestrial power applications. To assess the potential for ratchetting and its effect on durability of high temperature structures requires a viscoplastic analysis of the design. But ratchetting is a very difficult phenomenon to accurately model. One must therefore ask whether the results from such an analysis are indicative of actual material behavior, or if they are artifacts of the theory being used in the analysis. There are several subtle aspects in a viscoplastic model that must be dealt with in order to accurately model ratchetting behavior, and therefore obtain meaningful predictions from it. In this paper, some of these subtlties and the necessary ratchet experiments needed to obtain an accurate viscoplastic representation of a material are discussed

Brownian ratchets from statistical physics to bio and nano-motors

CERN Document Server

Cubero, David

2016-01-01

Illustrating the development of Brownian ratchets, from their foundations, to their role in the description of life at the molecular scale and in the design of artificial nano-machinery, this text will appeal to both advanced graduates and researchers entering the field. Providing a self-contained introduction to Brownian ratchets, devices which rectify microscopic fluctuations, Part I avoids technicalities and sets out the broad range of physical systems where the concept of ratchets is relevant. Part II supplies a single source for a complete and modern theoretical analysis of ratchets in regimes such as classical vs quantum and stochastic vs deterministic, and in Part III readers are guided through experimental developments in different physical systems, each highlighting a specific unique feature of ratchets. The thorough and systematic approach to the topic ensures that this book provides a complete guide to Brownian ratchets for newcomers and established researchers in physics, biology and biochemistry.

Ratchet device with broken friction symmetry

DEFF Research Database (Denmark)

Norden, Bengt; Zolotaryuk, Yaroslav; Christiansen, Peter Leth

2002-01-01

An experimental setup (gadget) has been made for demonstration of a ratchet mechanism induced by broken symmetry of a dependence of dry friction on external forcing. This gadget converts longitudinal oscillating or fluctuating motion into a unidirectional rotation, the direction of which is in ac......An experimental setup (gadget) has been made for demonstration of a ratchet mechanism induced by broken symmetry of a dependence of dry friction on external forcing. This gadget converts longitudinal oscillating or fluctuating motion into a unidirectional rotation, the direction of which...... is in accordance with given theoretical arguments. Despite the setup being three dimensional, the ratchet rotary motion is proved to be described by one simple dynamic equation. This kind of motion is a result of the interplay of friction and inertia....

Study of flow induce vibration inside 3.5 inch hard disk drives

Directory of Open Access Journals (Sweden)

Wichitpon Seepangmon

2014-06-01

Full Text Available This study focused on flow induced vibration of head stack assembly (HSA in a 3.5 inch hard disk drive with 5 disks and 10 read/write heads. We studied the effects of air flow on gimbal flex and resonance on arm. The comparison of vibrations on slider between the normal model and the experiment has been done for verifying the model. The peaks of frequency in experiment match the normal model at 1,040 1,320 and 1,400 Hz respectively. After that, the RNG K-ε turbulence model was used to determine the turbulent air flow of 7,200 rpm hard disk drive. The comparison between the normal model and the model with spoiler was investigated by using, computational fluid dynamics software (ANSYS and FLUENT. The results shown velocity magnitudes at the arm were decreased by 0.725 - 57.689 % and pressure dropped by 74.028 - 87.222 %. The velocity magnitudes at the gimbal flex were decreased by 5.522 - 14.291 % and pressure dropped by 48.440 - 82.947 %. The peak of vibrations on arm and gimbal flex was occurred at the frequency 1200 Hz. The model with spoiler could reduce vibration at arm by 2.56 - 95.601 % and reduce vibration at gimbal flex by 4.065 - 95.503 %. In the conclusion, the model with a spoiler could decrease the vibration at all surface of the arm and gimbal flex due to the velocity and pressure reduction[1][4].

Granular Segregation by an Oscillating Ratchet Mechanism

International Nuclear Information System (INIS)

Igarashi, A.; Horiuchi, Ch.

2004-01-01

We report on a method to segregate granular mixtures which consist of two kinds of particles by an oscillating ''ratchet'' mechanism. The segregation system has an asymmetrical sawtooth-shaped base which is vertically oscillating. Such a ratchet base produces a directional current of particles owing to its transport property. It is a counterintuitive and interesting phenomenon that a vertically vibrated base transports particles horizontally. This system is studied with numerical simulations, and it is found that we can apply such a system to segregation of mixtures of particles with different properties (radius or mass). Furthermore, we find out that an appropriate inclination of the ratchet-base makes the quality of segregation high. (author)

Clarification of strain limits considering the ratcheting fatigue strength of 316FR steel

International Nuclear Information System (INIS)

Isobe, Nobuhiro; Sukekawa, Masayuki; Nakayama, Yasunari; Date, Shingo; Ohtani, Tomomi; Takahashi, Yukio; Kasahara, Naoto; Shibamoto, Hiroshi; Nagashima, Hideaki; Inoue, Kazuhiko

2008-01-01

The effect of ratcheting on fatigue strength was investigated in order to rationalize the strain limit as a design criterion of commercialized fast reactor systems. Ratcheting fatigue tests were conducted at 550 deg. Duration of the ratchet straining was set for a certain number of strain cycles taking the loading condition of fast reactors into account, and the number of cycles for strain accumulation was defined as the ratchet-expired cycle. Fatigue lives decrease as the accumulated strain by ratcheting increases. Mean stress increased during the ratcheting cycle and its maximum value depended on the accumulated strain and the ratchet-expired cycle. Fatigue life reduction was negligible when the maximum mean stress was less than 25 MPa, corresponding to an accumulated strain of 2.2%. Accumulated strain is limited to 2% in the present design guidelines and this strain limit is considered effective to avoid reducing fatigue life by ratcheting. Microcrack growth behaviors were also investigated in these tests in order to discuss the life reduction mechanisms in ratcheting conditions

Ratcheting failure of pressurised straight pipes and elbows under reversed bending

International Nuclear Information System (INIS)

Vishnuvardhan, S.; Raghava, G.; Gandhi, P.; Saravanan, M.; Goyal, Sumit; Arora, Punit; Gupta, Suneel K.; Bhasin, Vivek

2013-01-01

Ratcheting studies were carried out on Type 304LN stainless steel straight pipes and elbows subjected to steady internal pressure and cyclic bending load. The internal pressure for all the straight pipes was 35 MPa and in the case of elbows the internal pressure was varied for different elbows, ranging from 27.6 MPa to 39.2 MPa. Cyclic bending load was applied on the specimens by subjecting them to different levels of load-line displacement. The specimens have undergone significant ratchet swelling (ballooning), ovalization and consequent thinning of the cross-section during ratcheting. The straight pipes failed either by occurrence of through-wall crack accompanied by simultaneous ballooning, or bursting with simultaneous ballooning. All the elbows failed by occurrence of through-wall crack accompanied by simultaneous ballooning. Ratcheting behaviour of straight pipes and elbows were compared and it was generally inferred that ratcheting was more pronounced in straight pipes than in elbows. -- Graphical abstract: Strain history for the specimen QCE-RAT-6-L1. Highlights: • Studies were carried out under combined internal pressure and cyclic bending. • Ratcheting strains were measured at critical locations of the specimens. • Quantified the percentage of ballooning, ovalization and reduction in thickness. • Modes of ratcheting failure of straight pipes and elbows are studied. • Inferred that ratcheting is more pronounced in straight pipes than in elbows

Quantum ratchet effect in a time non-uniform double-kicked model

Science.gov (United States)

Chen, Lei; Wang, Zhen-Yu; Hui, Wu; Chu, Cheng-Yu; Chai, Ji-Min; Xiao, Jin; Zhao, Yu; Ma, Jin-Xiang

2017-07-01

The quantum ratchet effect means that the directed transport emerges in a quantum system without a net force. The delta-kicked model is a quantum Hamiltonian model for the quantum ratchet effect. This paper investigates the quantum ratchet effect based on a time non-uniform double-kicked model, in which two flashing potentials alternately act on a particle with a homogeneous initial state of zero momentum, while the intervals between adjacent actions are not equal. The evolution equation of the state of the particle is derived from its Schrödinger equation, and the numerical method to solve the evolution equation is pointed out. The results show that quantum resonances can induce the ratchet effect in this time non-uniform double-kicked model under certain conditions; some quantum resonances, which cannot induce the ratchet effect in previous models, can induce the ratchet effect in this model, and the strengths of the ratchet effect in this model are stronger than those in previous models under certain conditions. These results enrich people’s understanding of the delta-kicked model, and provides a new optional scheme to control the quantum transport of cold atoms in experiment.

Near-Field, On-Chip Optical Brownian Ratchets.

Science.gov (United States)

Wu, Shao-Hua; Huang, Ningfeng; Jaquay, Eric; Povinelli, Michelle L

2016-08-10

Nanoparticles in aqueous solution are subject to collisions with solvent molecules, resulting in random, Brownian motion. By breaking the spatiotemporal symmetry of the system, the motion can be rectified. In nature, Brownian ratchets leverage thermal fluctuations to provide directional motion of proteins and enzymes. In man-made systems, Brownian ratchets have been used for nanoparticle sorting and manipulation. Implementations based on optical traps provide a high degree of tunability along with precise spatiotemporal control. Here, we demonstrate an optical Brownian ratchet based on the near-field traps of an asymmetrically patterned photonic crystal. The system yields over 25 times greater trap stiffness than conventional optical tweezers. Our technique opens up new possibilities for particle manipulation in a microfluidic, lab-on-chip environment.

Polymer deformation in Brownian ratchets: theory and molecular dynamics simulations.

Science.gov (United States)

Kenward, Martin; Slater, Gary W

2008-11-01

We examine polymers in the presence of an applied asymmetric sawtooth (ratchet) potential which is periodically switched on and off, using molecular dynamics (MD) simulations with an explicit Lennard-Jones solvent. We show that the distribution of the center of mass for a polymer in a ratchet is relatively wide for potential well depths U0 on the order of several kBT. The application of the ratchet potential also deforms the polymer chains. With increasing U0 the Flory exponent varies from that for a free three-dimensional (3D) chain, nu=35 (U0=0), to that corresponding to a 2D compressed (pancake-shaped) polymer with a value of nu=34 for moderate U0. This has the added effect of decreasing a polymer's diffusion coefficient from its 3D value D3D to that of a pancaked-shaped polymer moving parallel to its minor axis D2D. The result is that a polymer then has a time-dependent diffusion coefficient D(t) during the ratchet off time. We further show that this suggests a different method to operate a ratchet, where the off time of the ratchet, toff, is defined in terms of the relaxation time of the polymer, tauR. We also derive a modified version of the Bader ratchet model [Bader, Proc. Natl. Acad. Sci. U.S.A. 96, 13165 (1999)] which accounts for this deformation and we present a simple expression to describe the time dependent diffusion coefficient D(t). Using this model we then illustrate that polymer deformation can be used to modulate polymer migration in a ratchet potential.

Shock initiation experiments on ratchet grown PBX 9502

Energy Technology Data Exchange (ETDEWEB)

Gustavsen, Richard L [Los Alamos National Laboratory; Thompson, Darla G [Los Alamos National Laboratory; Olinger, Barton W [Los Alamos National Laboratory; Deluca, Racci [Los Alamos National Laboratory; Bartram, Brian D [Los Alamos National Laboratory; Pierce, Timothy H [Los Alamos National Laboratory; Sanchez, Nathaniel J [Los Alamos National Laboratory

2010-01-01

This study compares the shock initiation behavior of PBX 9502 pressed to less than nominal density (nominal density is 1.890 {+-} 0.005 g/cm{sup 3}) with PBX 9502 pressed to nominal density and then ''ratchet grown'' to low density. PBX 9502 is an insensitive plastic bonded explosive consisting of 95 weight % dry-aminated tri-amino-tri-nitro-benzene (TATB) and 5 weight % Kel-F 800 plastic binder. ''Ratchet growth'' - an irreversible increase in specific volume - occurs when an explosive based on TATB is temperature cycled. The design of our study is as follows: PBX 9502, all from the same lot, received the following four treatments. Samples in the first group were pressed to less than nominal density. These were not ratchet grown and used as a baseline. Samples in the second group were pressed to nominal density and then ratchet grown by temperature cycling 30 times between -54 C and +80 C. Samples in the final group were pressed to nominal density and cut into 100 mm by 25.4 mm diameter cylinders. During thermal cycling the cylinders were axially constrained by a 100 psi load. Samples for shock initiation experiments were cut perpendicular (disks) and parallel (slabs) to the axial load. The four sample groups can be summarized with the terms pressed low, ratchet grown/no load, axial load/disks, and axial load/slabs. All samples were shock initiated with nearly identical inputs in plate impact experiments carried out on a gas gun. Wave profiles were measured after propagation through 3, 4, 5, and 6 mm of explosive. Side by side comparison of wave profiles from different samples is used as a measure of relative sensitivity. All reduced density samples were more shock sensitive than nominal density PBX 9502. Differences in shock sensitivity between ratchet grown and pressed to low density PBX 9502 were small, but the low density pressings are slightly more sensitive than the ratchet grown samples.

Solution of the ratchet-shakedown Bree problem with an extra orthogonal primary load

International Nuclear Information System (INIS)

Bradford, R.A.W.

2015-01-01

The complete shakedown and ratcheting solution is derived analytically for a flat plate subject to unequal biaxial primary membrane stresses and a cyclic secondary bending stress in one in-plane direction (x). The Tresca yield condition and elastic-perfectly plastic behaviour are assumed. It is shown that the results can be expressed in the form of a “universal” ratchet diagram applicable for all magnitudes of orthogonal load. For sufficiently large cyclic bending stresses, tensile ratcheting can occur in the x direction if the x direction primary membrane stress exceeds half that in the orthogonal direction. Conversely, for sufficiently large cyclic bending stresses ratcheting in the x direction will be compressive if the x direction primary membrane stress is less than half that in the orthogonal direction. When the x direction primary membrane stress is exactly half that in the orthogonal direction ratcheting cannot occur however large the cyclic secondary bending stress. - Highlights: • A complete shakedown and ratcheting solution is derived analytically. • The problem is Bree-like but with an extra orthogonal primary load. • The ratchet diagram can be expressed in a form applicable to any orthogonal load. • Tensile ratcheting can occur if the primary load exceeds half the orthogonal load. • Compressive ratcheting can occur for smaller primary loads

Multiaxial ratcheting behavior of zirconium alloy tubes under combined cyclic axial load and internal pressure

Energy Technology Data Exchange (ETDEWEB)

Chen, G.; Zhang, X. [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Xu, D.K. [Environmental Corrosion Center, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Li, D.H. [Hunan Taohuajiang Nuclear Power Co., Ltd, Yiyang, 413000 (China); Chen, X. [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Zhang, Z., E-mail: zhe.zhang@tju.edu.cn [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

2017-06-15

In this study, a series of uniaxial and multiaxial ratcheting tests were conducted at room temperature on zirconium alloy tubes. The experimental results showed that for uniaxial symmetrical cyclic test, the axial ratcheting strain ɛ{sub x} did not accumulate obviously in initial stage, but gradually increased up to 1% with increasing stress amplitude σ{sub xa}. For multiaxial ratcheting tests, the zirconium alloy tube was highly sensitive to both the axial stress amplitude σ{sub xa} and the internal pressure p{sub i}. The hoop ratcheting strain ɛ{sub θ} increased continuously with the increase of axial stress amplitude, whereas the evolution of axial ratcheting strain ɛ{sub x} was related to the axial stress amplitude. The internal pressure restricted the ratcheting accumulation in the axial direction, but promoted the hoop ratcheting strain on the contrary. The prior loading history greatly restrained the ratcheting behavior of subsequent cycling with a small internal pressure. - Highlights: •Uniaxial and multiaxial ratcheting behavior of the zirconium alloy tubes are investigated at room temperature. •The ratcheting depends greatly on the stress amplitude or internal pressure. •The interaction between the axial and hoop ratcheting mechanisms is greatly dependent on the internal pressure level. •The ratcheting is influenced significantly by the loading history of internal pressure.

Multiaxial ratcheting behavior of zirconium alloy tubes under combined cyclic axial load and internal pressure

International Nuclear Information System (INIS)

Chen, G.; Zhang, X.; Xu, D.K.; Li, D.H.; Chen, X.; Zhang, Z.

2017-01-01

In this study, a series of uniaxial and multiaxial ratcheting tests were conducted at room temperature on zirconium alloy tubes. The experimental results showed that for uniaxial symmetrical cyclic test, the axial ratcheting strain ɛ x did not accumulate obviously in initial stage, but gradually increased up to 1% with increasing stress amplitude σ xa . For multiaxial ratcheting tests, the zirconium alloy tube was highly sensitive to both the axial stress amplitude σ xa and the internal pressure p i . The hoop ratcheting strain ɛ θ increased continuously with the increase of axial stress amplitude, whereas the evolution of axial ratcheting strain ɛ x was related to the axial stress amplitude. The internal pressure restricted the ratcheting accumulation in the axial direction, but promoted the hoop ratcheting strain on the contrary. The prior loading history greatly restrained the ratcheting behavior of subsequent cycling with a small internal pressure. - Highlights: •Uniaxial and multiaxial ratcheting behavior of the zirconium alloy tubes are investigated at room temperature. •The ratcheting depends greatly on the stress amplitude or internal pressure. •The interaction between the axial and hoop ratcheting mechanisms is greatly dependent on the internal pressure level. •The ratcheting is influenced significantly by the loading history of internal pressure.

Regional Atmospheric Transport Code for Hanford Emission Tracking, Version 2 (RATCHET2)

International Nuclear Information System (INIS)

Ramsdell, James V.; Rishel, Jeremy P.

2006-01-01

This manual describes the atmospheric model and computer code for the Atmospheric Transport Module within SAC. The Atmospheric Transport Module, called RATCHET2, calculates the time-integrated air concentration and surface deposition of airborne contaminants to the soil. The RATCHET2 code is an adaptation of the Regional Atmospheric Transport Code for Hanford Emissions Tracking (RATCHET). The original RATCHET code was developed to perform the atmospheric transport for the Hanford Environmental Dose Reconstruction Project. Fundamentally, the two sets of codes are identical; no capabilities have been deleted from the original version of RATCHET. Most modifications are generally limited to revision of the run-specification file to streamline the simulation process for SAC.

Regional Atmospheric Transport Code for Hanford Emission Tracking, Version 2(RATCHET2)

Energy Technology Data Exchange (ETDEWEB)

Ramsdell, James V.; Rishel, Jeremy P.

2006-07-01

This manual describes the atmospheric model and computer code for the Atmospheric Transport Module within SAC. The Atmospheric Transport Module, called RATCHET2, calculates the time-integrated air concentration and surface deposition of airborne contaminants to the soil. The RATCHET2 code is an adaptation of the Regional Atmospheric Transport Code for Hanford Emissions Tracking (RATCHET). The original RATCHET code was developed to perform the atmospheric transport for the Hanford Environmental Dose Reconstruction Project. Fundamentally, the two sets of codes are identical; no capabilities have been deleted from the original version of RATCHET. Most modifications are generally limited to revision of the run-specification file to streamline the simulation process for SAC.

Micro rectennas: Brownian ratchets for thermal-energy harvesting

International Nuclear Information System (INIS)

Pan, Y.; Powell, C. V.; Balocco, C.; Song, A. M.

2014-01-01

We experimentally demonstrated the operation of a rectenna for harvesting thermal (blackbody) radiation and converting it into dc electric power. The device integrates an ultrafast rectifier, the self-switching nanodiode, with a wideband log-periodic spiral microantenna. The radiation from the thermal source drives the rectenna out of thermal equilibrium, permitting the rectification of the excess thermal fluctuations from the antenna. The power conversion efficiency increases with the source temperatures up to 0.02% at 973 K. The low efficiency is attributed mainly to the impedance mismatch between antenna and rectifier, and partially to the large field of view of the antenna. Our device not only opens a potential solution for harvesting thermal energy but also provides a platform for experimenting with Brownian ratchets

Micro rectennas: Brownian ratchets for thermal-energy harvesting

Science.gov (United States)

Pan, Y.; Powell, C. V.; Song, A. M.; Balocco, C.

2014-12-01

We experimentally demonstrated the operation of a rectenna for harvesting thermal (blackbody) radiation and converting it into dc electric power. The device integrates an ultrafast rectifier, the self-switching nanodiode, with a wideband log-periodic spiral microantenna. The radiation from the thermal source drives the rectenna out of thermal equilibrium, permitting the rectification of the excess thermal fluctuations from the antenna. The power conversion efficiency increases with the source temperatures up to 0.02% at 973 K. The low efficiency is attributed mainly to the impedance mismatch between antenna and rectifier, and partially to the large field of view of the antenna. Our device not only opens a potential solution for harvesting thermal energy but also provides a platform for experimenting with Brownian ratchets.

Micro rectennas: Brownian ratchets for thermal-energy harvesting

Energy Technology Data Exchange (ETDEWEB)

Pan, Y.; Powell, C. V.; Balocco, C., E-mail: claudio.balocco@durham.ac.uk [School of Engineering and Computing Sciences, Durham University, Durham DH1 3LE (United Kingdom); Song, A. M. [School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL (United Kingdom)

2014-12-22

We experimentally demonstrated the operation of a rectenna for harvesting thermal (blackbody) radiation and converting it into dc electric power. The device integrates an ultrafast rectifier, the self-switching nanodiode, with a wideband log-periodic spiral microantenna. The radiation from the thermal source drives the rectenna out of thermal equilibrium, permitting the rectification of the excess thermal fluctuations from the antenna. The power conversion efficiency increases with the source temperatures up to 0.02% at 973 K. The low efficiency is attributed mainly to the impedance mismatch between antenna and rectifier, and partially to the large field of view of the antenna. Our device not only opens a potential solution for harvesting thermal energy but also provides a platform for experimenting with Brownian ratchets.

Harmonic ratcheting for fast acceleration

Science.gov (United States)

Cook, N.; Brennan, J. M.; Peggs, S.

2014-04-01

A major challenge in the design of rf cavities for the acceleration of medium-energy charged ions is the need to rapidly sweep the radio frequency over a large range. From low-power medical synchrotrons to high-power accelerator driven subcritical reactor systems, and from fixed focus alternating gradient accelerators to rapid cycling synchrotrons, there is a strong need for more efficient, and faster, acceleration of protons and light ions in the semirelativistic range of hundreds of MeV/u. A conventional way to achieve a large, rapid frequency sweep (perhaps over a range of a factor of 6) is to use custom-designed ferrite-loaded cavities. Ferrite rings enable the precise tuning of the resonant frequency of a cavity, through the control of the incremental permeability that is possible by introducing a pseudoconstant azimuthal magnetic field. However, rapid changes over large permeability ranges incur anomalous behavior such as the "Q-loss" and "f-dot" loss phenomena that limit performance while requiring high bias currents. Notwithstanding the incomplete understanding of these phenomena, they can be ameliorated by introducing a "harmonic ratcheting" acceleration scheme in which two or more rf cavities take turns accelerating the beam—one turns on when the other turns off, at different harmonics—so that the radio frequency can be constrained to remain in a smaller range. Harmonic ratcheting also has straightforward performance advantages, depending on the particular parameter set at hand. In some typical cases it is possible to halve the length of the cavities, or to double the effective gap voltage, or to double the repetition rate. This paper discusses and quantifies the advantages of harmonic ratcheting in general. Simulation results for the particular case of a rapid cycling medical synchrotron ratcheting from harmonic number 9 to 2 show that stability and performance criteria are met even when realistic engineering details are taken into consideration.

Ratcheting fatigue behavior of Zircaloy-2 at room temperature

Energy Technology Data Exchange (ETDEWEB)

Rajpurohit, R.S., E-mail: rsrajpurohit.rs.met13@iitbhu.ac.in [Department of Metallurgical Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi, 221005 (India); Sudhakar Rao, G. [Nuclear Energy and Safety Department, Paul Scherrer Institute, Villigen, CH-5232 (Switzerland); Chattopadhyay, K.; Santhi Srinivas, N.C.; Singh, Vakil [Department of Metallurgical Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi, 221005 (India)

2016-08-15

Nuclear core components of zirconium alloys experience asymmetric stress or strain cycling during service which leads to plastic strain accumulation and drastic reduction in fatigue life as well as dimensional instability of the component. Variables like loading rate, mean stress, and stress amplitude affect the influence of asymmetric loading. In the present investigation asymmetric stress controlled fatigue tests were conducted with mean stress from 80 to 150 MPa, stress amplitude from 270 to 340 MPa and stress rate from 30 to 750 MPa/s to study the process of plastic strain accumulation and its effect on fatigue life of Zircaloy-2 at room temperature. It was observed that with increase in mean stress and stress amplitude accumulation of ratcheting strain was increased and fatigue life was reduced. However, increase in stress rate led to improvement in fatigue life due to less accumulation of ratcheting strain. - Highlights: • Ratcheting strain accumulation occurred due to asymmetric cyclic loading. • Accumulation of ratcheting strain increased with mean stress and stress amplitude. • Ratcheting strain accumulation decreased with increase in stress rate. • With increase in mean stress and stress amplitude there was reduction in fatigue life. • Fatigue life is improved with increase in stress rate.

Ratcheting deformation of advanced 316 steel under creep-plasticity condition

Energy Technology Data Exchange (ETDEWEB)

Kawashima, Fumiko; Ishikawa, Akiyoshi; Asada, Yasuhide [Tokai Univ., Tokyo (Japan). Dept. of Mechanical Engineering

1998-11-01

Tension-torsion biaxial ratcheting tests have been conducted with Advanced 316 Steel (316FR Steel) at 650 C under a cyclic strain rate of 10{sup -3} to 10{sup -5} s{sup -1}. Accumulation of ratcheting strain has been measured. Accumulated ratchet strain has shown to be much larger than predicted based on a usual method of the linear superposition of strains due to creep and plasticity. The result shows there observed the creep-plasticity interaction in the observation. (orig.)

A study on thermal ratcheting structure test of 316L test cylinder

International Nuclear Information System (INIS)

Lee, H. Y.; Kim, J. B.; Koo, G. H.

2001-01-01

In this study, the progressive inelastic deformation, so called, thermal ratchet phenomenon which can occur in high temperature liquid metal reactor was simulated with thermal ratchet structural test facility and 316L stainless steel test cylinder. The inelastic deformation of the reactor baffle cylinder can occur due to the moving temperature distribution along the axial direction as the hot free surface moves up and down under the cyclic heat-up and cool-down of reactor operations. The ratchet deformations were measured with the laser displacement sensor and LVDTs after cooling the structural specimen which experiences thermal load up to 550 .deg. C and the temperature differences of about 500 .deg. C. During structural thermal ratchet test, the temperature distribution of the test cylinder along the axial direction was measured from 28 channels of thermocouples and the temperatures were used for the ratchet analysis. The thermal ratchet deformation analysis was performed with the NONSTA code whose constitutive model is nonlinear combined kinematic and isotropic hardening model and the test results were compared with those of the analysis. Thermal ratchet test was carried out with respect to 9 cycles of thermal loading and the maximum residual displacements were measured to be 1.8mm. It was shown that thermal ratchet load can cause a progressive deformation to the reactor structure. The analysis results with the combined hardening model were in reasonable agreement with those of the tests

Thermal stress ratcheting analysis of a time-hardening structure

International Nuclear Information System (INIS)

Hada, Kazuhiko

1999-01-01

Thermal stress ratcheting and shakedown is analyzed for a time-hardening structure: the yield stress increases as time goes on under exposure to neutron irradiation or thermal aging. New three modes of ratcheting and shakedown are identified as transition to other deformation modes. Stress regimes and thermal ratchet strains are formulated as a function of time-increasing yield stress. Moreover, a new model of trouble occurrence frequency as a modification to a bath-tube curve is proposed for calculating a time period of a thermal cycle. Application of the proposed formulation tells us a benefit of taking into account the time hardening due to neutron irradiation. (author)

Dislocation based controlling of kinematic hardening contribution to simulate primary and secondary stages of uniaxial ratcheting

Science.gov (United States)

Bhattacharjee, S.; Dhar, S.; Acharyya, S. K.

2017-07-01

The primary and secondary stages of the uniaxial ratcheting curve for the C-Mn steel SA333 have been investigated. Stress controlled uniaxial ratcheting experiments were conducted with different mean stresses and stress amplitudes to obtain curves showing the evolution of ratcheting strain with number of cycles. In stage-I of the ratcheting curve, a large accumulation of ratcheting strain occurs, but at a decreasing rate. In contrast, in stage-II a smaller accumulation of ratcheting strain is found and the ratcheting rate becomes almost constant. Transmission electron microscope observations reveal that no specific dislocation structures are developed during the early stages of ratcheting. Rather, compared with the case of low cycle fatigue, it is observed that sub-cell formation is delayed in the case of ratcheting. The increase in dislocation density as a result of the ratcheting strain is obtained using the Orowan equation. The ratcheting strain is obtained from the shift of the plastic strain memory surface. The dislocation rearrangement is incorporated in a functional form of dislocation density, which is used to calibrate the parameters of a kinematic hardening law. The observations are formulated in a material model, plugged into the ABAQUS finite element (FE) platform as a user material subroutine. Finally the FE-simulated ratcheting curves are compared with the experimental curves.

Implementing Demons and Ratchets

Directory of Open Access Journals (Sweden)

Peter M. Orem

2017-01-01

Full Text Available Experimental results show that ratchets may be implemented in semiconductor and chemical systems, bypassing the second law and opening up huge gains in energy production. This paper summarizes or describes experiments and results on systems that effect demons and ratchets operating in chemical or electrical domains. One creates temperature differences that can be harvested by a heat engine. A second produces light with only heat input. A third produces harvestable electrical potential directly. These systems share creating particles in one location, destroying them in another and moving them between locations by diffusion (Brownian motion. All absorb ambient heat as they produce other energy forms. None requires an external hot and cold side. The economic and social impacts of these conversions of ambient heat to work are, of course, well-understood and huge. The experimental results beg for serious work on the chance that they are valid.

Constitutive modeling for uniaxial time-dependent ratcheting of SS304 stainless steel

International Nuclear Information System (INIS)

Kan Qianhua; Kang Guozheng; Zhang Juan

2007-01-01

Based on the experimental results of uniaxial time-dependent ratcheting behavior of SS304 stainless steel at room temperature and 973K, a new time-dependent constitutive model was proposed. The model describes the time-dependent ratcheting by adding a static/thermal recovery into the Abdel-Karim-Ohno non-linear kinematic hardening rule. The capability of the model to describe the time-dependent ratcheting was discussed by comparing the simulations with the corresponding experimental results. It is shown that the revised unified viscoplastic model can simulate the time-dependent ratcheting reasonably both at room and high temperatures. (authors)

Evaluation of thermal ratcheting of reactor vessel wall near the sodium surface

International Nuclear Information System (INIS)

Take, Kohji; Fujioka, Terutaka; Yano, Kazutaka

1989-01-01

Plastic ratcheting of reactor vessels may occur by an axially moving thermal gradient without primary stress. So there is a need to establish a proper prediction method for the plastic ratcheting. In this study, inelastic FEM analyses of reactor vessel model by using an advanced constitutive equation were carried out in order to comprehend plastic ratcheting behaviour of cylinder which subject to an axially moving thermal gradient. As a result of analyses, a basic mechanism of this ratcheting was found. And it also indicated that cyclic hardening behaviour will became important for development of evaluation method. (author)

Cyclic mechanical behavior of 316L: Uniaxial LCF and strain-controlled ratcheting tests

International Nuclear Information System (INIS)

Facheris, G.; Janssens, K.G.F.

2013-01-01

Highlights: ► Characterization of cyclic plastic deformation behavior of plate and tubular 316L. ► Strain-controlled ratcheting response between room temperature and 200 °C. ► Isotropic cyclic hardening is dependent on the yield criterion used. ► Ratcheting induced hardening mostly affects the kinematic hardening component. ► Ratcheting induced hardening is related to the mean strain and the ratcheting rate. -- Abstract: With the purpose of analyzing the fatigue behavior under loading conditions relevant for the primary cooling circuit of a light water nuclear reactor, a set of uniaxial low cycle fatigue and strain-controlled ratcheting tests (also named ‘cyclic tension tests’) has been performed at room temperature and at 200 °C on specimens manufactured from two different batches of stainless steel grade 316L. The experiments have been repeated varying strain amplitude, cyclic ratcheting rate and ratcheting direction in order to investigate the influence on the cyclic deformation behavior. In strain-controlled ratcheting tests, the stress response is found to be a superposition of two hardening mechanisms: the first one due to the zero mean strain cycling and the second one linked with the monotonic drifting of mean plastic strain. An approach is proposed to distinguish the effect of each mechanism and the influence of the test parameters on the hardening mechanisms is discussed

Modelization of ratcheting in biaxial experiments

International Nuclear Information System (INIS)

Guionnet, C.

1989-08-01

A new unified viscoplastic constitutive equation has been developed in order to interpret ratcheting experiments on mechanical structures of fast reactors. The model is based essentially on a generalized Armstrong Frederick equation for the kinematic variable; the coefficients of the dynamic recovery term in this equation is a function of both instantaneous and accumulated inelastic strain which is allowed to vary in an appropriate manner in order to reproduce the experimental ratcheting rate. The validity of the model is verified by comparing predictions with experimental results for austenitic stainless steel (17-12 SPH) tubular specimens subjected to cyclic torsional loading under constant tensile stress at 600 0 C [fr

Control-oriented approaches to anticipating synchronization of chaotic deterministic ratchets

Energy Technology Data Exchange (ETDEWEB)

Xu Shiyun [State Key Lab for Turbulence and Complex Systems, Department of Mechanics and Aerospace Engineering, College of Engineering, Peking University, Beijing 100871 (China)], E-mail: xushiyun@pku.edu.cn; Yang Ying [State Key Lab for Turbulence and Complex Systems, Department of Mechanics and Aerospace Engineering, College of Engineering, Peking University, Beijing 100871 (China)], E-mail: yy@mech.pku.edu.cn; Song Lei [State Key Lab for Turbulence and Complex Systems, Department of Mechanics and Aerospace Engineering, College of Engineering, Peking University, Beijing 100871 (China)

2009-06-15

In virtue of techniques derived from nonlinear control system theory, we establish conditions under which one could obtain anticipating synchronization between two periodically driven deterministic ratchets that are able to exhibit directed transport with a finite velocity. Criteria are established in order to guarantee the anticipating synchronization property of such systems as well as characterize phase space dynamics of the ratchet transporting behaviors. These results allow one to predict the chaotic direct transport features of particles on a ratchet potential using a copy of the same system that performs as a slave, which are verified through numerical simulation.

Thermo-mechanical ratcheting in jointed rock masses

KAUST Repository

Pasten, C.

2015-09-01

Thermo-mechanical coupling takes place in jointed rock masses subjected to large thermal oscillations. Examples range from exposed surfaces under daily and seasonal thermal fluctuations to subsurface rock masses affected by engineered systems such as geothermal operations. Experimental, numerical and analytical results show that thermo-mechanical coupling can lead to wedging and ratcheting mechanisms that result in deformation accumulation when the rock mass is subjected to a biased static-force condition. Analytical and numerical models help in identifying the parameter domain where thermo-mechanical ratcheting can take place.

Thermo-mechanical ratcheting in jointed rock masses

KAUST Repository

Pasten, C.; Garcí a, M.; Santamarina, Carlos

2015-01-01

Thermo-mechanical coupling takes place in jointed rock masses subjected to large thermal oscillations. Examples range from exposed surfaces under daily and seasonal thermal fluctuations to subsurface rock masses affected by engineered systems such as geothermal operations. Experimental, numerical and analytical results show that thermo-mechanical coupling can lead to wedging and ratcheting mechanisms that result in deformation accumulation when the rock mass is subjected to a biased static-force condition. Analytical and numerical models help in identifying the parameter domain where thermo-mechanical ratcheting can take place.

Engineering Autonomous Chemomechanical Nanomachines Using Brownian Ratchets

Science.gov (United States)

Lavella, Gabriel

Nanoscale machines which directly convert chemical energy into mechanical work are ubiquitous in nature and are employed to perform a diverse set of tasks such as transporting molecules, maintaining molecular gradients, and providing motion to organisms. Their widespread use in nature suggests that large technological rewards can be obtained by designing synthetic machines that use similar mechanisms. This thesis addresses the technological adaptation of a specific mechanism known as the Brownian ratchet for the design of synthetic autonomous nanomachines. My efforts were focused more specifically on synthetic chemomechanical ratchets which I deem will be broadly applicable in the life sciences. In my work I have theoretically explored the biophysical mechanisms and energy landscapes that give rise to the ratcheting phenomena and devised devices that operate off these principles. I demonstrate two generations of devices that produce mechanical force/deformation in response to a user specified ligand. The first generation devices, fabricatied using a combination nanoscale lithographic processes and bioconjugation techniques, were used to provide evidence that the proposed ratcheting phenomena can be exploited in synthetic architectures. Second generation devices fabricated using self-assembled DNA/hapten motifs were constructed to gain a precise understanding of ratcheting dynamics and design constraints. In addition, the self-assembled devices enabled fabrication en masse, which I feel will alleviate future experimental hurdles in analysis and facilitate its adaptation to technologies. The product of these efforts is an architecture that has the potential to enable numerous technologies in biosensing and drug delivery. For example, the coupling of molecule-specific actuation to the release of drugs or signaling molecules from nanocapsules or porous materials could be transformative. Such architectures could provide possible avenues to pressing issues in biology and

Seismic ratchet-fatigue failure of piping systems

International Nuclear Information System (INIS)

Severud, L.K.; Anderson, M.J.; Lindquist, M.R.; Weiner, E.O.

1986-01-01

Failures of piping systems during earthquakes have been rare. Those that have failed were either made of brittle material such as cast iron, were rigid systems between major components where component relative seismic motions tore the pipe out of the component, or were high pressure systems where a ratchet-fatigue fracture followed a local bulging of the pipe diameter. Tests to failure of an unpressurized 3-in. and a pressurized 6-in. diameter carbon steel nuclear pipe systems subjected to high level shaking have been accomplished. Failure analyses of these tests are presented and correlated to the test results. It was found that failure of the unpressurized system could be correlated well with standard ASME type fatigue analysis predictions. Moreover, the pressurized system failure occurred in significantly less load cycles than predicted by standard fatigue analysis. However, a ratchet-fatigue and ductility exhaustion analysis of the pressurized system did correlate very well. These findings indicate modifications to design analysis methods and the present ASME Code piping design rules may be appropriate to cover the ratchet-fatigue failure mode

Ratchetting deformation behavior of modified 9Cr-1Mo steel and applicability of existing constitutive models

International Nuclear Information System (INIS)

Yaguchi, Masatsugu; Takahashi, Yukio

2001-01-01

A series of ratchetting deformation tests was conducted on modified 9Cr-1Mo steel at 550degC under uniaxial and multiaxial stress conditions. Ratchetting behavior depended on various parameters such as mean stress, stress/strain rate and those range, hold time and prior cyclic deformation. Under uniaxial conditions, untraditional ratchetting behavior was observed; the ratchetting deformation rate was the fastest when the stress ratio was equal to -1, while no ratchetting deformation was predicted by conventional constitutive models. In order to discuss the reason for this untraditional ratchetting behavior, a lot of monotonic compression tests were conducted and compared with tension data. The material showed a difference of deformation resistance of about 30 MPa between tension and compression at high strain rates. Furthermore, the authors' previous model and Ohno-Wang model were applied to the test conditions to evaluate their description capability for ratchetting behavior of the material. It was shown that the authors' model has a tendency to overestimate the ratchetting deformation and that the Ohno-Wang model has a tendency to underestimate the uniaxial ratchetting deformation at small stress rates. (author)

Test and analysis of thermal ratcheting deformation for 316L stainless steel cylindrical structure

International Nuclear Information System (INIS)

Lee, Hyeong Yeon; Kim, Jong Bum; Lee, Jae Han

2002-01-01

In this study, the progressive inelastic deformation, so called, thermal ratchet phenomenon which can occur in high temperature structures of liquid metal simulated with thermal ratchet structural test facility and 316L stainless steel test cylinder. The thermal ratchet deformation at the reactor baffle cylinder of the liquid metal reactor can occur due to the moving temperature distribution along the axial direction as the sodium free surface moves up and down under the cyclic heat-up and cool-down transients. The ratchet deformation was measured with the laser displacement sensor and LVDTs after cooling the structural specimen which is heated up to 550 degree C with steep temperature gradients along the axial direction. The temperature distribution of the test cylinder along the axial direction was measured with 28 channels of thermocouples and was used for the ratchet analysis. The thermal ratchet deformation was analyzed with the constitutive equation of nonlinear combined hardening model which was implemented as ABAQUS user subroutine and the analysis results were compared with those of the test. Thermal ratchet load was applied 9 times and the residual displacement after 9 cycles of thermal load was measured to be 1.79 mm. The ratcheting deformation shapes obtained by the analysis with the combined hardening model were in reasonable agreement with those of the structural tests

Thermal ratcheting and creep damage

International Nuclear Information System (INIS)

Clement, G.; Cousseran, P.; Roche, R.L.

1983-01-01

Several proposals have been made to assist adesigners with thermal ratcheting in the creep range, the more known has been made by O'DONNELL and POROWSKY. Unfortunately these methods are not validated by experiments, and they take only inelastic distortion into consideration as creep effects. The aim of the work presented here is to correct these deficiencies - in providing an experimental basis to ratcheting analysis rules in the creep range, - in considering the effect of cyclic straining (like cyclic thermal stresses) on the time to rupture by creep. Experimental tests have been performed on austenitic stainless steel at 650 0 C for the first item. Results of these tests and results available in the open literature have been used to built a practical rule of ratcheting analysis. This rule giving a conservative value of the creep distortion, is based on the concept of effective primary stress which is an amplification of the primary stress really applied. Concerning the second point (time to rupture), it was necessary to obtain real creep rupture and not instability. According to the proposal of Pr LECKIE, tests were performed on specimens made out of copper, and of aluminium alloys at temperatures between 150 0 C and 300 0 C. With such materials creep rupture is obtained without necking. Experimental tests show that cyclic straining reduces the time to creep rupture under load controlled stress. Caution must be given to the designer: cyclic thermal stress can lead to premature creep rupture. (orig./GL)

Effects of kinematic hardening rules on thermal ratchetting analysis of cylinders subjected to cyclically moving temperature distribution

International Nuclear Information System (INIS)

Ohno, N.; Kobayashi, M.

1995-01-01

In the present work, thermal ratchetting in a cylinder subjected to a cyclically moving temperature front (i.e. liquid surface induced thermal ratchetting) was analyzed by implementing in a finite element method the four kinds of plasticity models with different kinematic hardening rules. The following findings were thus obtained concerning effects of the kinematic hardening rules on the analysis. (1) If transition nonlinear hardening after yielding is disregarded, the thermal ratchetting becomes significant, as seen in the results of the PP and LKH models. Especially the PP model, which does not express any strain hardening, predicts steady development of the thermal ratchetting. (2) If significant mechanical ratchetting is allowed in the modeling of kinematic hardening, the thermal ratchetting becomes marked, as seen in the results of the AF model. (3) Model dependence of the thermal ratchetting is more noticeable when the difference of temperature at the temperature front, ΔT, is smaller. (4) The OW model makes the thermal ratchetting stop at a smaller number of cycles when ΔT is smaller. On the other hand, the LKH and AF models allow that the thermal ratchetting to develop more constantly when ΔT is smaller. As seen from the above findings, the analysis of liquid surface induced thermal ratchetting has great dependence on the kinematic hardening rules employed. Especially the PP model, which has been used often to analyze the thermal ratchetting so far, gives too large development of the thermal ratchetting. Thus we may say that in order to improve the analysis it is necessary to use an appropriate kinematic hardening model which is capable of expressing appropriately both mechanical ratchetting and transient nonlinear hardening after yielding. (author)

Quantum ratchets for quantum communication with optical superlattices

International Nuclear Information System (INIS)

Romero-Isart, Oriol; Garcia-Ripoll, Juan Jose

2007-01-01

We propose to use a quantum ratchet to transport quantum information in a chain of atoms trapped in an optical superlattice. The quantum ratchet is created by a continuous modulation of the optical superlattice which is periodic in time and in space. Though there is zero average force acting on the atoms, we show that indeed the ratchet effect permits atoms on even and odd sites to move along opposite directions. By loading the optical lattice with two-level bosonic atoms, this scheme permits us to perfectly transport a qubit or entangled state imprinted in one or more atoms to any desired position in the lattice. From the quantum computation point of view, the transport is achieved by a smooth concatenation of perfect swap gates. We analyze setups with noninteracting and interacting particles and in the latter case we use the tools of optimal control to design optimal modulations. We also discuss the feasibility of this method in current experiments

Ratcheting study in pressurized piping components under cyclic loading at room temperature

International Nuclear Information System (INIS)

Ravi Kiran, A.; Agrawal, M.K.; Reddy, G.R.; Vaze, K.K.; Ghosh, A.K.; Kushwaha, H.S.

2006-07-01

The nuclear power plant piping components and systems are often subjected to reversing cyclic loading conditions due to various process transients, seismic and other events. Earlier the design of piping subjected to seismic excitation was based on the principle of plastic collapse. It is believed that during such events, fatigue-ratcheting is likely mode of failure of piping components. The 1995 ASME Boiler and Pressure Vessel code, Section-III, has incorporated the reverse dynamic loading and ratcheting into the code. Experimental and analytical studies are carried out to understand this failure mechanism. The biaxial ratcheting characteristics of SA 333, Gr. 6 steel and SS 304 stainless steel at room temperature are investigated in the present work. Experiments are carried out on straight pipes subjected to internal pressure and cyclic bending load applied in a three point and four point bend test configurations. A shake table test is also carried out on a pressurized elbow by applying sinusoidal base excitation. Analytical simulation of ratcheting in the piping elements is carried out. Chaboche nonlinear kinematic hardening model is used for ratcheting simulation. (author)

Ratcheting problems for ITER [International Thermonuclear Experimental Reactor

International Nuclear Information System (INIS)

Majumdar, S.

1991-01-01

Because of the presence of high cyclic thermal stress, pressure-induced primary stress, and disruption-induced high cyclic primary stress, ratcheting of the first wall poses a serious challenge to the designers of ITER (International Thermonuclear Experimental Reactor). Existing design tools such as the Bree diagram in the ASME Boiler and Pressure Vessels Code, are not directly applicable to ITER, because of important differences in geometry and loading modes. Available alternative models for ratcheting are discussed and new Bree diagrams, that are more relevant for fusion reactor applications, are proposed. 9 refs., 17 figs

Investigations on the ratchetting behaviour of austenitic pipes

International Nuclear Information System (INIS)

Kraemer, D.; Krolop, S.; Scheffold, A.; Stegmeyer, R.

1994-01-01

Reversed bending tests at room temperature with pipes with and without internal pressure were carried out. The pipes were manufactured from the austenitic steel X10 CrNiNb 18 9. Under internal pressure ratchetting was observed in circumferential direction. The component tests were accompanied by numerical computations using a nonlinear kinematic hardening rule and superposed isotropic hardening. In total the constitutive model needed 13 parameters to be fitted when isotropic hardening resulted in a cyclic saturation. Uniaxial monotonic and cyclic loading tests served for characterizing the material. A reasonable parameter fitting with respect to describe ratchetting required load controlled nonzero mean-stress tests. On condition, that the loading will lead to cyclic saturation, ratchetting could be well predicted in the pipe with the found set of parameters. An extension of the isotropic hardening rule in the constitutive model was proposed allowing to describe various types of isotropic hardening. In a first step it was shown that under uniaxial conditions the extension reproduces continuous isotropic hardening up to incipient cracking quite well. (orig.)

Monte Carlo simulations of interacting particle mixtures in ratchet potentials

International Nuclear Information System (INIS)

Fendrik, A J; Romanelli, L

2012-01-01

There are different models of devices for achieving a separation of mixtures of particles by using the ratchet effect. On the other hand, it has been proposed that one could also control the separation by means of appropriate interactions. Through Monte Carlo simulations, we show that inclusion of simple interactions leads to a decrease of the ratchet effect and therefore also a separation of the mixtures.

Thermal ratcheting and creep damage

International Nuclear Information System (INIS)

Clement, G.; Cousseran, P.; Roche, R.L.

1983-08-01

Creep is a cause of deformation; it may also result in rupture in time. Although LMFBR structures are not heavily loaded, they are subjected to large thermal transients. Can structure lifetime be shortened by such transients. Several proposals have been made to assist adesigners with thermal ratcheting in the creep range. Unfortunately these methods are not validated by experiments, and they take only inelastic distorsion into consideration as creep effects. The aim of the work presented here is to correct these deficiencies in providing an experimental basis to ratcheting analysis rules in the creep range, and in considering the effect of cyclic straining (like cyclic thermal stresses) on the time to rupture by creep. Experimental tests have been performed on austenitic stainless steel at 650 0 C for the first item. Results of these tests and results available in the open literature have been used to built a practical rule of ratcheting analysis. This rule giving a conservative value of the creep distortion, is based on the concept of effective primary stress which is an amplification of the primary stress really applied. Concerning the second point (time to rupture), it was necessary to obtain real creep rupture and not instability. According to the proposal of Pr LECKIE, tests were performed on specimen made out of copper, and of aluminium alloys at temperatures between 150 0 C and 300 0 C. With such materials creep rupture is obtained without necking. Experimental tests show that cyclic straining reduces the time to creep rupture under load controlled stress. Caution must be given to the designer: cyclic thermal stress can lead to premature creep rupture

A Ratchet Lens: Black Queer Youth, Agency, Hip Hop, and the Black Ratchet Imagination

Science.gov (United States)

Love, Bettina L.

2017-01-01

This article explores the utilization of the theory of a Black ratchet imagination as a methodological perspective to examine the multiple intersections of Black and queer identity constructions within the space of hip hop. In particular, I argue for the need of a methodological lens that recognizes, appreciates, and struggles with the fluidity,…

Effective Brownian ratchet separation by a combination of molecular filtering and a self-spreading lipid bilayer system.

Science.gov (United States)

Motegi, Toshinori; Nabika, Hideki; Fu, Yingqiang; Chen, Lili; Sun, Yinlu; Zhao, Jianwei; Murakoshi, Kei

2014-07-01

A new molecular manipulation method in the self-spreading lipid bilayer membrane by combining Brownian ratchet and molecular filtering effects is reported. The newly designed ratchet obstacle was developed to effectively separate dye-lipid molecules. The self-spreading lipid bilayer acted as both a molecular transport system and a manipulation medium. By controlling the size and shape of ratchet obstacles, we achieved a significant increase in the separation angle for dye-lipid molecules compared to that with the previous ratchet obstacle. A clear difference was observed between the experimental results and the simple random walk simulation that takes into consideration only the geometrical effect of the ratchet obstacles. This difference was explained by considering an obstacle-dependent local decrease in molecular diffusivity near the obstacles, known as the molecular filtering effect at nanospace. Our experimental findings open up a novel controlling factor in the Brownian ratchet manipulation that allow the efficient separation of molecules in the lipid bilayer based on the combination of Brownian ratchet and molecular filtering effects.

Flashing subdiffusive ratchets in viscoelastic media

International Nuclear Information System (INIS)

Kharchenko, Vasyl; Goychuk, Igor

2012-01-01

We study subdiffusive ratchet transport in periodically and randomly flashing potentials. A central Brownian particle is elastically coupled to the surrounding auxiliary Brownian quasi-particles, which account for the influence of the viscoelastic environment. Similar to standard dynamical modeling of Brownian motion, the external force influences only the motion of the central particle, not affecting directly the environmental degrees of freedom. Just a handful of auxiliary Brownian particles suffices to model subdiffusion over many temporal decades. Time modulation of the potential violates the symmetry of thermal detailed balance and induces an anomalous subdiffusive current which exhibits a remarkably small dispersion at low temperatures, as well as a number of other surprising features such as saturation at low temperatures, and multiple inversions of the transport direction upon a change of the driving frequency in the non-adiabatic regime. It is shown that the subdiffusive current is finite at zero temperature for random flashing and can be finite for periodic flashing for a certain frequency window. Our study generalizes classical Brownian motors towards operating in sticky viscoelastic environments such as the cytosol of biological cells or dense polymer solutions. (paper)

Evaluation of fatigue-ratcheting damage of a pressurised elbow undergoing damage seismic inputs

International Nuclear Information System (INIS)

Dang Van, K.

2000-01-01

We present a simplified method to calculate the plastic ratchet of elbow-shaped pipes submitted to seismic loading and an internal pressure. This method is simplified in the sense that the value of the ratchet is obtained without the use of finite element method (FEM) calculations. Here we derive a formula and use it to evaluate the fatigue-ratcheting damage of an elbow. This approach is applicable to complex plastic response appropriately described by non-linear kinematics hardening, which is more realistic for stainless steel such as 316-L. (orig.)

The Leverage Ratchet Effect

OpenAIRE

Anat R. Admati; Peter M. DeMarzo; Martin F. Hellwig; Paul Pfleiderer

2013-01-01

Shareholder-creditor conflicts can create leverage ratchet effects, resulting in inefficient capital structures. Once debt is in place, shareholders may inefficiently increase leverage but avoid reducing it no matter how beneficial leverage reduction might be to total firm value. We present conditions for an irrelevance result under which shareholders view asset sales, pure recapitalization and asset expansion with new equity as equally undesirable. We then analyze how seniority, asset hetero...

A new approach for primary overloads allowance in ratcheting evaluation

International Nuclear Information System (INIS)

Cabrillat, M.T.; Gatt, J.M.; Lejeail, Y.

1995-01-01

Seismic loading must be taken into account in ratchetting design analysis. In LMFBR structures it mainly produces primary overloads, which are characterised by severe magnitudes but a generally low number of occurrences. Other cases of several primary overloads can also observed in pipes during emptying operations for instance. In the RCC-MR design code rule, the maximum primary stress supported by a structure is considered as permanent. No allowance is made for temporary load. Experimental ratchetting tests conducted on different structures with and without overloads clearly point out that temporary overloads lead to less ratchetting effect. A method using the RCC-MR efficiency diagram framework is proposed. A general theoretical approach allows to extend its field of application of various cases of primary loading: constant or null primary loading or overloads. Experimental results are then used to check the validity of this new approach. (author). 2 refs., 2 figs., 2 tabs

A three-bar model for ratcheting of fusion reactor first wall

International Nuclear Information System (INIS)

Wolters, J.; Majumdar, S.

1994-12-01

First wall structures of fusion reactors are subjected to cyclic bending stresses caused by inhomogeneous temperature distribution during plasma burn cycles and by electromagnetically induced impact loads during plasma disruptions. Such a combination of loading can potentially lead to ratcheting or incremental accumulation of plastic strain with cycles. An elastic-plastic three-bar model is developed to investigate the ratcheting behavior of the first wall

Experimental study on uniaxial ratcheting deformation and failure behavior of 304 stainless steel

International Nuclear Information System (INIS)

Yang Xianjie; Gao Qing; Cai Lixun; Liu Yujie

2004-01-01

In the paper, the tests of cyclic strain ratcheting and low cycle fatigue for 304 stainless steel under uniaxial cyclic straining were carried out to systematically explore the deformation and failure behavior of the material. The experimental study shows that the cyclic strain ratcheting deformation behavior of the material is different from either the uniaxial monotonic tensile one or the cyclic deformation one under the symmetrical cyclic straining with the same strain amplitude, and the strain ratcheting deformation and failure behaviors depend on both the plastic strain amplitude and the strain increment at the cyclic maximum strain. Some significant results were observed

Collective ratchet effects and reversals for active matter particles on quasi-one-dimensional asymmetric substrates.

Science.gov (United States)

McDermott, Danielle; Olson Reichhardt, Cynthia J; Reichhardt, Charles

2016-10-19

Using computer simulations, we study a two-dimensional system of sterically interacting self-mobile run-and-tumble disk-shaped particles with an underlying periodic quasi-one-dimensional asymmetric substrate, and show that a rich variety of collective active ratchet behaviors arise as a function of particle density, activity, substrate period, and the maximum force exerted by the substrate. The net dc drift, or ratchet transport flux, is nonmonotonic since it increases with increased activity but is diminished by the onset of self-clustering of the active particles. Increasing the particle density decreases the ratchet transport flux for shallow substrates but increases the ratchet transport flux for deep substrates due to collective hopping events. At the highest particle densities, the ratchet motion is destroyed by a self-jamming effect. We show that it is possible to realize reversals of the direction of the net dc drift in the deep substrate limit when multiple rows of active particles can be confined in each substrate minimum, permitting emergent particle-like excitations to appear that experience an inverted effective substrate potential. We map out a phase diagram of the forward and reverse ratchet effects as a function of the particle density, activity, and substrate properties.

A design rule about thermal ratcheting

International Nuclear Information System (INIS)

Clement, G.; Lebey, J.; Roche, R.L.

1984-01-01

The purpose of this paper is to present an analysis of thermal ratcheting, and to give a practical design rule aimed at avoiding its detrimental effects. A practical method will thus be available to designers for dealing with one of the adverse effects of computed thermal stresses

Ratchet Effects and Domain Wall Energy Landscapes in Amorphous Magnetic Films with 2D Arrays of Asymmetric Holes

Science.gov (United States)

Martin, J. I.; Alija, A.; Sobrado, I.; Perez-Junquera, A.; Rodriguez-Rodriguez, G.; Velez, M.; Alameda, J. M.; Marconi, V. I.; Kolton, A. B.; Parrondo, J. M. R.

2009-03-01

The driven motion of domain walls in extended magnetic films patterned with 2D arrays of asymmetric holes has been found to be subject to two different crossed ratchet effects [1] which results in an inversion of the sign of domain wall motion rectification as a function of the applied magnetic field. This effect can be understood in terms of the competition between drive, elasticity and asymmetric pinning as revealed by a simple 4̂-model. In order to optimize the asymmetric hole design, the relevant energy landscapes for domain wall motion across the array of asymmetric holes have been calculated by micromagnetic simulations as a function of array geometrical characteristics. The effects of a transverse magnetic field on these two crossed ratchet effects will also be discussed in terms of the decrease in domain wall energy per unit area and of the modifications in the magnetostatic barriers for domain wall pinning at the asymmetric inclusions. Work supported by Spanish MICINN.[1] A. Perez-Junquera et al, Phys. Rev. Lett. 100 (2008) 037203

Transverse ratchet effect and superconducting vortices: simulation and experiment

International Nuclear Information System (INIS)

Dinis, L; Parrondo, J M R; Perez de Lara, D; Gonzalez, E M; Vicent, J L; Anguita, J V

2009-01-01

A transverse ratchet effect has been measured in magnetic/superconducting hybrid films fabricated by electron beam lithography and magnetron sputtering techniques. The samples are Nb films grown on top of an array of Ni nanotriangles. Injecting an ac current parallel to the triangle reflection symmetry axis yields an output dc voltage perpendicular to the current, due to a net motion of flux vortices in the superconductor. The effect is reproduced by numerical simulations of vortices as Langevin particles with realistic parameters. Simulations provide an intuitive picture of the ratchet mechanism, revealing the fundamental role played by the random intrinsic pinning of the superconductor.

Segregation of granular binary mixtures by a ratchet mechanism.

Science.gov (United States)

Farkas, Zénó; Szalai, Ferenc; Wolf, Dietrich E; Vicsek, Tamás

2002-02-01

We report on a segregation scheme for granular binary mixtures, where the segregation is performed by a ratchet mechanism realized by a vertically shaken asymmetric sawtooth-shaped base in a quasi-two-dimensional box. We have studied this system by computer simulations and found that most binary mixtures can be segregated using an appropriately chosen ratchet, even when the particles in the two components have the same size and differ only in their normal restitution coefficient or friction coefficient. These results suggest that the components of otherwise nonsegregating granular mixtures may be separated using our method.

Shaping of Rack Cutter Original Profile for Fine-module Ratchet Teeth Cutting

Science.gov (United States)

Sharkov, O. V.; Koryagin, S. I.; Velikanov, N. L.

2018-05-01

The design models and the process of shaping the cutting edges of the rack cutter for cutting fine-module ratchet teeth are considered in the article. The use of fine-module ratchet teeth can reduce the noise and impact loads during operation of the freewheel mechanisms. Mathematical dependencies for calculating the coordinates determining the geometric position of the points of the front and back edges of the cutting profile of the rack cutter, the workpiece angle of rotation during cutting the ratchet teeth were obtained. When applying the developed method, the initial data are: the radii of the workpiece circumferences passing through the dedendum of the external and internal cut teeth; gradient angles of the front and back edges of the rail.

The Bree problem with different yield stresses on-load and off-load and application to creep ratcheting

International Nuclear Information System (INIS)

Bradford, R.A.W.; Ure, J.; Chen, H.F.

2014-01-01

The ratchet boundaries and ratchet strains are derived for the Bree problem and an elastic-perfectly plastic material with different yield stresses on-load and off-load. The Bree problem consists of a constant uniaxial primary membrane stress and a cycling thermal bending stress. The ratchet problem with differing yield stresses is also solved for a modified loading in which both the primary membrane and thermal bending stresses cycle in-phase. The analytic solutions for the ratchet boundaries are compared with the results of deploying the linear matching method (LMM) and excellent agreement is found. Whilst these results are of potential utility for purely elastic–plastic behaviour, since yield stresses will often differ at the two ends of the cycle, the solution is also proposed as a means of assessing creep ratcheting via a creep ductility exhaustion approach. -- Highlights: • The Bree problem is solved for differing yield stresses on and off load. • The modified Bree problem with cycling primary load is also solved. • These solutions can be applied to creep ratcheting using a pseudo-yield stress

Quasi-static and ratcheting properties of trabecular bone under uniaxial and cyclic compression.

Science.gov (United States)

Gao, Li-Lan; Wei, Chao-Lei; Zhang, Chun-Qiu; Gao, Hong; Yang, Nan; Dong, Li-Min

2017-08-01

The quasi-static and ratcheting properties of trabecular bone were investigated by experiments and theoretical predictions. The creep tests with different stress levels were completed and it is found that both the creep strain and creep compliance increase rapidly at first and then increase slowly as the creep time goes by. With increase of compressive stress the creep strain increases and the creep compliance decreases. The uniaxial compressive tests show that the applied stress rate makes remarkable influence on the compressive behaviors of trabecular bone. The Young's modulus of trabecular bone increases with increase of stress rate. The stress-strain hysteresis loops of trabecular bone under cyclic load change from sparse to dense with increase of number of cycles, which agrees with the change trend of ratcheting strain. The ratcheting strain rate rapidly decreases at first, and then exhibits a relatively stable and small value after 50cycles. Both the ratcheting strain and ratcheting strain rate increase with increase of stress amplitude or with decrease of stress rate. The creep model and the nonlinear viscoelastic constitutive model of trabecular bone were proposed and used to predict its creep property and rate-dependent compressive property. The results show that there are good agreements between the experimental data and predictions. Copyright © 2017 Elsevier B.V. All rights reserved.

Amnioserosa cell constriction but not epidermal actin cable tension autonomously drives dorsal closure.

Science.gov (United States)

Pasakarnis, Laurynas; Frei, Erich; Caussinus, Emmanuel; Affolter, Markus; Brunner, Damian

2016-11-01

Tissue morphogenesis requires coordination of multiple force-producing components. During dorsal closure in fly embryogenesis, an epidermis opening closes. A tensioned epidermal actin/MyosinII cable, which surrounds the opening, produces a force that is thought to combine with another MyosinII force mediating apical constriction of the amnioserosa cells that fill the opening. A model proposing that each force could autonomously drive dorsal closure was recently challenged by a model in which the two forces combine in a ratchet mechanism. Acute force elimination via selective MyosinII depletion in one or the other tissue shows that the amnioserosa tissue autonomously drives dorsal closure while the actin/MyosinII cable cannot. These findings exclude both previous models, although a contribution of the ratchet mechanism at dorsal closure onset remains likely. This shifts the current view of dorsal closure being a combinatorial force-component system to a single tissue-driven closure event.

Ratcheting of pressurized piping subjected to seismic loading

International Nuclear Information System (INIS)

Scavuzzo, R.J.; Lam, P.C.; Gau, J.S.

1992-01-01

The ABAQUS finite element code was used to model a pressurized pipe and subjected to cyclic bending loads to investigate ratcheting. A 1-in. schedule 40 pipe was loaded with a slow (static) cyclic load. The pipe internal pressure was varied from 0 to 6000 psi. In this paper, two types of materials were considered: an elastic perfectly plastic and a bilinear elastic-plastic material. Two types of finite elements of the ABAQUS program were compared to analytical solutions to evaluate the element accuracy in the plastic regime. Depending upon loading conditions and specified material properties, three different responses were observed from the finite element analyses: cyclic plasticity, ratcheting of the hoop strain, or shakedown. These analytical results are compared to some experimental measurements

Firm Innovation and the Ratchet Effect Among Consumer Packaged Goods Firms

OpenAIRE

Christine Moorman; Simone Wies; Natalie Mizik; Fredrika J. Spencer

2012-01-01

We consider how public firms influence their stock market valuations by timing the introduction of innovative new products. Our focus is on innovation ratchet strategy --firms timing the introduction of innovations in order to demonstrate an improvement in the number of introductions over time. We document that public firms use an innovation ratchet strategy more often than do private firms and that the stock market rewards public firms for doing so. These rewards from the stock market, howev...

Zeeman ratchets: pure spin current generation in mesoscopic conductors with non-uniform magnetic fields

International Nuclear Information System (INIS)

Scheid, Matthias; Bercioux, Dario; Richter, Klaus

2007-01-01

We consider the possibility to employ a quantum wire realized in a two-dimensional electron gas (2DEG) as a spin ratchet. We show that a net spin current without accompanying net charge transport can be induced in the nonlinear regime by an unbiased external driving via an ac voltage applied between the contacts at the ends of the quantum wire. To achieve this, we make use of the coupling of the electron spin to inhomogeneous magnetic fields created by ferromagnetic stripes patterned on the semiconductor heterostructure that harbors the 2DEG. Using recursive Green function techniques, we numerically study two different set-ups, consisting of one and two ferromagnetic stripes, respectively

Experimental tests on ratchet of structural elements diagrams for primary tension and secondary twist

International Nuclear Information System (INIS)

Lebey, J.; Roche, R.L.; Cousseran, P.

1980-05-01

Design by analysis of pressure vessels is not complete without an appraisal of failure by progressive distortion or stress ratchet. Ratchet tests under constant axial stress associated with cyclic torsion deformation have been carried out on 304 L and 316 L thin tubular specimens, at room temperature. Results are given in the form of iso-deformation curves ranging from 0.1% to 2.5%, in the field definite by the primary and secondary stress intensities (Bree's diagram type). The use of an effective primary stress is proposed, as a practical way, to assess the elongation due to the ratchet effect

Ratcheting and low cycle fatigue behavior of SA333 steel and their life prediction

International Nuclear Information System (INIS)

Paul, Surajit Kumar; Sivaprasad, S.; Dhar, S.; Tarafder, S.

2010-01-01

Ratcheting and low cycle fatigue (LCF) experiments have been conducted at 25 o C temperature in laboratory environment under different loading conditions. SA333 steel exhibits cyclic hardening throughout its life during LCF. It is found that ratcheting strain increases with both increasing mean stress and stress amplitude. It has also been noticed that plastic strain amplitude and plastic strain energy decrease with increase in mean stress at constant stress amplitude. Ratcheting and LCF life in the range of 10 2 -10 5 cycles have been predicted with the help of a mean stress-based fatigue lifing equation.

Uniaxial ratcheting behavior of sintered nanosilver joint for electronic packaging

International Nuclear Information System (INIS)

Chen, Gang; Yu, Lin; Mei, Yunhui; Li, Xin; Chen, Xu; Lu, Guo-Quan

2014-01-01

Uniaxial ratcheting behavior and the fatigue life of sintered nanosilver joint were investigated at room temperature. All tests were carried out under stress-controlled mode. Force–displacement data were recorded during the entire fatigue lifespan by a non-contact displacement detecting system. Effects of stress amplitude, mean stress, stress rate, and stress ratio on the uniaxial ratcheting behavior of the sintered nanosilver joint were discussed. Stress-life (S–N) curves of the sintered joints were also obtained. The Smith–Watson–Topper (SWT) model, the Gerber model and the modified Goodman model, all of which took effect of mean stress into consideration, were compared for predicting the fatigue life of the sintered joint. Both the ratcheting strain and its rate increased with increasing stress amplitude or mean stress. The increase in stress amplitude and mean stress both reduced the fatigue life of the sintered joint, while the fatigue life prolonged with the increase in stress rate and stress ratio. The modified Goodman model predicted the fatigue life of the sintered joints well

A simplified approach for ratcheting analysis in structures with elastic follow-up

International Nuclear Information System (INIS)

Berton, M.N.; Cabrillat, M.T.

1991-01-01

In the framework of an elastic analysis, the RCC-MR design code uses the concept of the efficiency diagram to assess the behaviour of a structure relatively to ratcheting. This diagram was obtained from a lot of experimental results and allows to cover many reactor situations. However this approach needs to classify stresses between primary and secondary stresses and for a few cases, in particular for structures with significant elastic follow-up, this classification is not obvious. After a recall of elastic follow-up definition and a few considerations on the way to evaluate it, an approach is proposed to take it into account in an elastic analysis verifying the avoidance of ratcheting. An experimental program has been developed to study this interaction between elastic follow-up and ratcheting. The first results are presented together with interpretations with the proposed method. (author)

Prediction of ratcheting behaviour of 304 SS cylindrical shell using the Chaboche model

International Nuclear Information System (INIS)

Lee, Hyeong-Yeon; Kim, Jong Bum; Lee, Jae-Han; Yoo, Bong

1997-01-01

Ratcheting, that is, a progressive cyclic inelastic deformation can occur in a component subjected to thermal secondary stress, mechanical stress or both in the presence of a primary stress. The circumferential plastic strain may be accumulated with the increase of the number of cycles when a cylinder is subjected to a temperature front moving cyclically in the axial direction. This phenomenon of liquid surface induced thermal ratcheting is important in the design of liquid metal reactor. The ratcheting behaviour of a thin-walled 304 stainless steel cylinder under axially moving temperature distribution was analyzed using the constitutive theory of Chaboche. The constitutive model was implemented as a user subroutine of ABAQUS and it was verified through the comparison with the exact solutions for the uniaxial cyclic loading and test results available in the literature for the cylinder. In addition, ratcheting in pressurized push-pull pipes under loading conditions of ± 1% axial strain with steady hoop stress was analyzed with Chaboche model. It is shown that the elastic-plastic analysis using Chaboche model can evaluate properly the progressive strain accumulation under secondary cyclic loads. (author). 10 refs, 11 figs., 1 tab

Analysis and application of ratcheting evaluation procedure of Japanese high temperature design code DDS

International Nuclear Information System (INIS)

Lee, H. Y.; Kim, J. B.; Lee, J. H.

2002-01-01

In this study, the evaluation procedure of Japanese DDS code which was recently developed to assess the progressive inelastic deformation occurring under repetition of secondary stresses was analyzed and the evaluation results according to DDS was compared those of the thermal ratchet structural test carried out by KAERI to analyze the conservativeness of the code. The existing high temperature codes of US ASME-NH and French RCC-MR suggest the limited ratcheting procedures for only the load cases of cyclic secondary stresses under primary stresses. So they are improper to apply to the actual ratcheting problem which can occur under cyclic secondary membrane stresses due to the movement of hot free surface for the pool type LMR. DDS provides explicitly an analysis procedure of ratcheting due to moving thermal gradients near hot free surface. A comparison study was carried out between the results by the design code of DDS and by the structural test to investigate the conservativeness of DDS code, which showed that the evaluation results by DDS were in good agreement with those of the structural test

Assessment methods for Bree-type ratcheting without the necessity of linearization of stresses and strains

International Nuclear Information System (INIS)

Fujioka, Terutaka

2015-01-01

This paper proposes methods for assessing Bree-type ratcheting in a cylinder subjected to constant internal pressure and cyclic thermal loading. The proposed methods are elastic analysis-route and elastic–plastic analysis-route. The former is based on the polynomial approximation of the elastic stress distributions for thermal stresses and the reference stress concept for estimating primary stress. The latter elastic–plastic route method is based on the concept of relative elastic core size. The methods proposed were validated by performing elastic–plastic finite element analyses of a smooth cylinder that exhibited Bree-type ratcheting. - Highlights: • Rationalization of the ratcheting assessment has been made. • The proposed methods include both elastic and elastic-plastic routes. • The elastic route method is based on skeletal point stress by elastic FEA. • The elastic-plastic route is based on elastic core size in elastic-plastic FEA. • These have been validated by elastic-plastic FEA causing Bree-type ratcheting

Analysis of thermal ratchetting of a cylinder subjected to axially moving temperature front. Effect of kinematic hardening rule

International Nuclear Information System (INIS)

Ohno, Nobutada; Yari, Takashi; Kobayashi, Mineo

1995-01-01

When a cylinder is subjected to a temperature front moving cyclically in the axial direction, the circumferential plastic strain may accumulate with the increase of the number of cycles. This is a thermal ratchetting problem induced by a liquid surface moving in a cylinder, and it is important especially in designing fast breeder reactors. In the present paper, the effect of kinematic hardening rule on the thermal ratchetting analysis is discussed by implementing the following four kinds of kinematic hardening rules in a finite element analysis; the perfectly plastic model (PP), the linear kinematic hardening rule (LKH), the classical nonlinear kinematic hardening rule of Armstrong and Frederick (AF), and the rule proposed recently by Ohno and Wang (OW). It is shown that disregard of transient hardening after yielding leads to overestimating the thermal ratchetting, that a rule predicting larger mechanical ratchetting under uniaxial cyclic loading makes the thermal ratchetting more serious, and that the Ohno and Wang rule can render the analysis most realistic among them. (author)

Effect of moving distance of temperature distribution on thermal ratchetting behavior of a FBR reactor vessel

International Nuclear Information System (INIS)

Ueta, Masahiro; Douzaki, Kouji; Takahashi, Yukio; Ooka, Yuji; Osaki, Toshio; Take, Kouji.

1992-01-01

It should be considered in a FBR reactor vessel design that thermal ratchetting might be caused by moving axial thermal gradient, in other words, moving sodium level. The behavior and the mechanism of ratchetting have almost become clear by studies for the past several years. A simplified evaluation method for ratchetting behavior has been proposed. However, the evaluation method has been shown to be excessively conservative by testing results. In this paper, the effect of moving distance of axial temperature distributions, which is one of main factors to be considered in precise estimation of ratchetting behavior, is studied by inelastic analyses. Based on the study, it is proposed to introduce a strain reducing factor taking account of residual stresses in the region of moving axial temperature distribution to the original evaluation method. The new method has been validated by comparing the prediction with results of both testing and the original method. (author)

Forespore engulfment mediated by a ratchet-like mechanism.

Science.gov (United States)

Broder, Dan H; Pogliano, Kit

2006-09-08

A key step in bacterial endospore formation is engulfment, during which one bacterial cell engulfs another in a phagocytosis-like process that normally requires SpoIID, SpoIIM, and SpoIIP (DMP). We here describe a second mechanism involving the zipper-like interaction between the forespore protein SpoIIQ and its mother cell ligand SpoIIIAH, which are essential for engulfment when DMP activity is reduced or SpoIIB is absent. They are also required for the rapid engulfment observed during the enzymatic removal of peptidoglycan, a process that does not require DMP. These results suggest the existence of two separate engulfment machineries that compensate for one another in intact cells, thereby rendering engulfment robust. Photobleaching analysis demonstrates that SpoIIQ assembles a stationary structure, suggesting that SpoIIQ and SpoIIIAH function as a ratchet that renders forward membrane movement irreversible. We suggest that ratchet-mediated engulfment minimizes the utilization of chemical energy during this dramatic cellular reorganization, which occurs during starvation.

Pattern formation in plastic liquid films on elastomers by ratcheting.

Science.gov (United States)

Huang, Jiangshui; Yang, Jiawei; Jin, Lihua; Clarke, David R; Suo, Zhigang

2016-04-20

Plastic liquids, also known as Bingham liquids, retain their shape when loads are small, but flow when loads exceed a threshold. We discovered that plastic liquid films coated on elastomers develop wavy patterns under cyclic loads. As the number of cycles increases, the wavelength of the patterns remains unchanged, but the amplitude of the patterns increases and then saturates. Because the patterns develop progressively under cyclic loads, we call this phenomenon as "patterning by ratcheting". We observe the phenomenon in plastic liquids of several kinds, and studied the effects of thickness, the cyclic frequency of the stretch, and the range of the stretch. Finite element simulations show that the ratcheting phenomenon can occur in materials described by a commonly used model of elastic-plastic deformation.

Mixed motion in deterministic ratchets due to anisotropic permeability

NARCIS (Netherlands)

Kulrattanarak, T.; Sman, van der R.G.M.; Lubbersen, Y.S.; Schroën, C.G.P.H.; Pham, H.T.M.; Sarro, P.M.; Boom, R.M.

2011-01-01

Nowadays microfluidic devices are becoming popular for cell/DNA sorting and fractionation. One class of these devices, namely deterministic ratchets, seems most promising for continuous fractionation applications of suspensions (Kulrattanarak et al., 2008 [1]). Next to the two main types of particle

Motional dispersions and ratchet effect in inertial systems

Indian Academy of Sciences (India)

without the application of any time-averaged external field is termed as ratchet effect [1]. This is necessarily a ... The effect can also be obtained if the system is driven periodically but time asymmetrically in such a way that the ..... Govt. of India for financial assistance (SR/FTP/PS-33/2004). References. [1] P Reimann, Phys.

Cooperation and competition between two symmetry breakings in a coupled ratchet

Science.gov (United States)

Li, Chen-Pu; Chen, Hong-Bin; Fan, Hong; Xie, Ge-Ying; Zheng, Zhi-Gang

2018-03-01

We investigate the collective mechanism of coupled Brownian motors in a flashing ratchet in the presence of coupling symmetry breaking and space symmetry breaking. The dependences of directed current on various parameters are extensively studied in terms of numerical simulations and theoretical analysis. Reversed motion can be achieved by modulating multiple parameters including the spatial asymmetry coefficient, the coupling asymmetry coefficient, the coupling free length and the coupling strength. The dynamical mechanism of these transport properties can be reasonably explained by the effective potential theory and the cooperation or competition between two symmetry breakings. Moreover, adjusting the Gaussian white noise intensity, which can induce weak reversed motion under certain condition, can optimize and manipulate the directed transport of the ratchet system.

Ratcheting Strain and Microstructure Evolution of AZ31B Magnesium Alloy under a Tensile-Tensile Cyclic Loading.

Science.gov (United States)

Yan, Zhifeng; Wang, Denghui; Wang, Wenxian; Zhou, Jun; He, Xiuli; Dong, Peng; Zhang, Hongxia; Sun, Liyong

2018-03-28

In this paper, studies were conducted to investigate the deformation behavior and microstructure change in a hot-rolled AZ31B magnesium alloy during a tensile-tensile cyclic loading. The relationship between ratcheting effect and microstructure change was discussed. The ratcheting effect in the material during current tensile-tensile fatigue loading exceeds the material's fatigue limit and the development of ratcheting strain in the material experienced three stages: initial sharp increase stage (Stage I); steady stage (Stage II); and final abrupt increase stage (Stage III). Microstructure changes in Stage I and Stage II are mainly caused by activation of basal slip system. The Extra Geometrically Necessary Dislocations (GNDs) were also calculated to discuss the relationship between the dislocation caused by the basal slip system and the ratcheting strain during the cyclic loading. In Stage III, both the basal slip and the {11-20} twins are found active during the crack propagation. The fatigue crack initiation in the AZ31B magnesium alloy is found due to the basal slip and the {11-20} tensile twins.

Ratcheting up the ratchet: on the evolution of cumulative culture

Science.gov (United States)

Tennie, Claudio; Call, Josep; Tomasello, Michael

2009-01-01

Some researchers have claimed that chimpanzee and human culture rest on homologous cognitive and learning mechanisms. While clearly there are some homologous mechanisms, we argue here that there are some different mechanisms at work as well. Chimpanzee cultural traditions represent behavioural biases of different populations, all within the species’ existing cognitive repertoire (what we call the ‘zone of latent solutions’) that are generated by founder effects, individual learning and mostly product-oriented (rather than process-oriented) copying. Human culture, in contrast, has the distinctive characteristic that it accumulates modifications over time (what we call the ‘ratchet effect’). This difference results from the facts that (i) human social learning is more oriented towards process than product and (ii) unique forms of human cooperation lead to active teaching, social motivations for conformity and normative sanctions against non-conformity. Together, these unique processes of social learning and cooperation lead to humans’ unique form of cumulative cultural evolution. PMID:19620111

Ratcheting up the ratchet: on the evolution of cumulative culture.

Science.gov (United States)

Tennie, Claudio; Call, Josep; Tomasello, Michael

2009-08-27

Some researchers have claimed that chimpanzee and human culture rest on homologous cognitive and learning mechanisms. While clearly there are some homologous mechanisms, we argue here that there are some different mechanisms at work as well. Chimpanzee cultural traditions represent behavioural biases of different populations, all within the species' existing cognitive repertoire (what we call the 'zone of latent solutions') that are generated by founder effects, individual learning and mostly product-oriented (rather than process-oriented) copying. Human culture, in contrast, has the distinctive characteristic that it accumulates modifications over time (what we call the 'ratchet effect'). This difference results from the facts that (i) human social learning is more oriented towards process than product and (ii) unique forms of human cooperation lead to active teaching, social motivations for conformity and normative sanctions against non-conformity. Together, these unique processes of social learning and cooperation lead to humans' unique form of cumulative cultural evolution.

Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET)

International Nuclear Information System (INIS)

Ramsdell, J.V. Jr.; Simonen, C.A.; Burk, K.W.

1994-02-01

The purpose of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate radiation doses that individuals may have received from operations at the Hanford Site since 1944. This report deals specifically with the atmospheric transport model, Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET). RATCHET is a major rework of the MESOILT2 model used in the first phase of the HEDR Project; only the bookkeeping framework escaped major changes. Changes to the code include (1) significant changes in the representation of atmospheric processes and (2) incorporation of Monte Carlo methods for representing uncertainty in input data, model parameters, and coefficients. To a large extent, the revisions to the model are based on recommendations of a peer working group that met in March 1991. Technical bases for other portions of the atmospheric transport model are addressed in two other documents. This report has three major sections: a description of the model, a user's guide, and a programmer's guide. These sections discuss RATCHET from three different perspectives. The first provides a technical description of the code with emphasis on details such as the representation of the model domain, the data required by the model, and the equations used to make the model calculations. The technical description is followed by a user's guide to the model with emphasis on running the code. The user's guide contains information about the model input and output. The third section is a programmer's guide to the code. It discusses the hardware and software required to run the code. The programmer's guide also discusses program structure and each of the program elements

Thermal ratcheting and progressive buckling

International Nuclear Information System (INIS)

Lebey, J.; Brouard, D.; Roche, R.L.

1983-01-01

Pure elastic buckling is not a frequent mode of failure and plastic deformations often occurs before buckling - like instability does. Elastic-plastic buckling is very difficult to analyse. The most important difficulty is the material modeling. In the elastic plastic buckling phenomena, small modifications of the material constitutive equation used are of great influence on the final result. When buckling cannot occurs, it is well known that distortion due to applied loads is greatly amplified when there is also some cyclic straining (like thermal stresses). This effect is called ratcheting - and thermal ratcheting when caused by cyclic thermal transients. As cyclic thermal stresses can be applied in addition of load able to cause buckling failure of a component, the question arise of the effect of cyclic thermal stresses on the critical buckling load. The aim of the work presented here is to answer that question: 'Is the critical buckling load reduced when cyclic straining is added'. It seems sensible to avoid premature computation based only on arbitrary assumptions and to prefer obtaining a sound experimental basis for analysis. Sufficient experimental knowledge is needed in order to check the validity of the material modeling (and imperfections) used in analysis. Experimental tests on buckling of compressed columns subjected to cyclic straining have been performed. These experiments are described and results are given. The most important result is cyclic straining reduces the critical buckling load. It appears that distortion can be increasing progressively during cyclic straining and that buckling can happen at last at compressive loads too small to cause buckling in the absence of cyclic straining. (orig./RW)

Off-Axis Ratcheting Behavior of Unidirectional Carbon/Epoxy Laminate under Asymmetric Cyclic Loading at High Temperature

Science.gov (United States)

2011-11-01

ply unidirectional carbon/epoxy laminates [0]12 were fabricated from the prepreg tape of P3252-20 (TORAY). They were laid up by hand and cured in...Off-Axis Ratcheting Behavior of Unidirectional Carbon/Epoxy Laminate under Asymmetric Cyclic Loading at High Temperature Takafumi Suzuki 1 and...Development of an engineering model for predicting the off-axis ratcheting behavior of a unidirectional CFRP laminate has been attempted. For this purpose

Quantifying the threat of extinction from Muller's ratchet in the diploid Amazon molly (Poecilia formosa

Directory of Open Access Journals (Sweden)

Loewe Laurence

2008-03-01

Full Text Available Abstract Background The Amazon molly (Poecilia formosa is a small unisexual fish that has been suspected of being threatened by extinction from the stochastic accumulation of slightly deleterious mutations that is caused by Muller's ratchet in non-recombining populations. However, no detailed quantification of the extent of this threat is available. Results Here we quantify genomic decay in this fish by using a simple model of Muller's ratchet with the most realistic parameter combinations available employing the evolution@home global computing system. We also describe simple extensions of the standard model of Muller's ratchet that allow us to deal with selfing diploids, triploids and mitotic recombination. We show that Muller's ratchet creates a threat of extinction for the Amazon molly for many biologically realistic parameter combinations. In most cases, extinction is expected to occur within a time frame that is less than previous estimates of the age of the species, leading to a genomic decay paradox. Conclusion How then does the Amazon molly survive? Several biological processes could individually or in combination solve this genomic decay paradox, including paternal leakage of undamaged DNA from sexual sister species, compensatory mutations and many others. More research is needed to quantify the contribution of these potential solutions towards the survival of the Amazon molly and other (ancient asexual species.

A new approach to quantify the additional effect of primary overloads on ratcheting

International Nuclear Information System (INIS)

Waeckel, N.; Faure, O.; Sperandio, M.; Cousin, M.; Taleb, L.

1991-01-01

Taking into account the temporary nature of overloads reduces the conservatism of the current RCC-MR rules for prevention of ratcheting. An empirical K factor determined by the BITUBE tests carried out at INSA LYON, permits to quantify the influence of short-term mechanical overloads by comparison with the case without overload. The prediction of ratcheting risks by the RCC-MR efficiency diagram using a fictitious increased primary load by a K-factor is more fitted to the design of structures submitted to seisms. From then on, taking advantage of the workability of the experimental device BITUBE a new tests program has begun to confirm the results expressed above. (author)

Electric generation and ratcheted transport of contact-charged drops

Science.gov (United States)

Cartier, Charles A.; Graybill, Jason R.; Bishop, Kyle J. M.

2017-10-01

We describe a simple microfluidic system that enables the steady generation and efficient transport of aqueous drops using only a constant voltage input. Drop generation is achieved through an electrohydrodynamic dripping mechanism by which conductive drops grow and detach from a grounded nozzle in response to an electric field. The now-charged drops are transported down a ratcheted channel by contact charge electrophoresis powered by the same voltage input used for drop generation. We investigate how the drop size, generation frequency, and transport velocity depend on system parameters such as the liquid viscosity, interfacial tension, applied voltage, and channel dimensions. The observed trends are well explained by a series of scaling analyses that provide insight into the dominant physical mechanisms underlying drop generation and ratcheted transport. We identify the conditions necessary for achieving reliable operation and discuss the various modes of failure that can arise when these conditions are violated. Our results demonstrate that simple electric inputs can power increasingly complex droplet operations with potential opportunities for inexpensive and portable microfluidic systems.

Effect of ratchet strain on fatigue and creep–fatigue strength of Mod.9Cr–1Mo steel

International Nuclear Information System (INIS)

Ando, Masanori; Isobe, Nobuhiro; Kikuchi, Koichi; Enuma, Yasuhiro

2012-01-01

Highlights: ► Uniaxial fatigue and creep–fatigue tests with superimposed strain were performed. ► Variety of superimposed strain were applied as ratchet strain in the tests. ► Effect of superimposed strain on fatigue and creep–fatigue life is negligible. ► A cyclic softening character reducing the effect of superimposed strain. - Abstract: The effect of ratcheting deformation on fatigue and creep–fatigue life in Mod.9Cr–1Mo steel was investigated. Uniaxial fatigue and creep–fatigue testing with superimposed strain were performed to evaluate the effect of ratcheting deformation on the failure cycle. In a series of tests, a specific amount of superimposed strain was accumulated in each cycle. The accumulated strain as ratcheting deformation, cycles to reach the accumulated strain, and test temperatures were varied in the tests. In the fatigue tests with superimposed strain at 550 °C, slight reductions of failure lives were observed. All of the numbers of cycles to failure in the fatigue tests with superimposed strain were within a factor of 1.5 of that of the fatigue test without superimposed strain at 550 °C. The apparent relationship between failure cycles and testing parameters was not observed. In fatigue tests with superimposed strain at 550 °C, maximum mean stress was insignificant and generated in early cycles because Mod.9Cr–1Mo steel exhibits cyclic softening characteristics. It was assumed that suppression of mean stress generation by cyclic softening reduces the effect of ratcheting strain. Conversely, failure lives were increased by accumulated strain in the test conducted at 450 °C because of stress–strain hysteresis loop shrinkage caused by cyclic softening induced by the accumulated strain. In the creep–fatigue tests with superimposed strain, test results indicated that the accumulated stain was negligible. It was concluded that the effect of ratcheting deformation on fatigue and creep–fatigue life is negligible as long

Simulation of ratcheting in straight pipes using ANSYS with an improved cyclic plasticity model

International Nuclear Information System (INIS)

Hassan, T.; Zhu, Y.; Matzen, V.C.

1996-01-01

Ratcheting has been shown to be a contributing cause of failure in several seismic experiments on piping components and systems. Most commercial finite element codes have been unable to simulate the ratcheting in those tests accurately. The reason for this can be traced to inadequate plasticity constitutive models in the analysis codes. The authors have incorporated an improved cyclic plasticity model, based on an Armstrong-Frederick kinematic hardening rule in conjunction with the Drucker-Palgen plastic modulus equation, into an ANSYS user subroutine. This modified analysis code has been able to simulate quite accurately the ratcheting behavior of a tube subjected to a constant internal pressure and axially strain controlled cycling. This paper describes simulations obtained form this modified ANSYS code for two additional tests: (1) a tube subjected to constant axial stress and prescribed torsional cycling, and (2) a straight pipe subjected to constant internal pressure and quasi-static cyclic bending. The analysis results from the modified ANSYS code are compared to the experimental data, as well as results from ABAQUS and the original ANSYS code. The resulting correlation shows a significant improvement over the original ANSYS and the ABAQUS codes

Dynamical analysis of an optical rocking ratchet: Theory and experiment

Czech Academy of Sciences Publication Activity Database

Arzola, Alejandro V.; Volke-Sepúlveda, K.; Mateos, J.L.

2013-01-01

Roč. 87, č. 6 (2013), 062910:1-9 ISSN 1539-3755 R&D Projects: GA MŠk LH12018; GA MŠk EE2.4.31.0016 Institutional support: RVO:68081731 Keywords : deterministic optical rocking ratchet * analysis of the dynamics Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.326, year: 2013

Shakedown and ratchetting below the creep range

International Nuclear Information System (INIS)

Ponter, A.R.S.

1983-01-01

The report reviews current understanding of the behaviour of structure subject to variable mechanical and thermal loading below the creep range through a comparison of theoretical solutions and experimental studies. The particular characteristics of the austenitic stainless steels are emphasized in components subject to moderate primary loads and large thermal loads. The review shows that a clear classification of types of thermal loading is required in design. Two main classes, termed category A and B, exist which arise not from the magnitude of the thermal stresses but their extent through the material volume of the structure. In category A situations, the Bree plate problem being the prime example, the maximum thermal stresses occur over a volume of the structure which does not contain a mechanism of failure. As a result very large thermal stresses may be withstood without ratchetting occurring for sufficiently small mechanical loads. For category B situations, the maximum thermal stress occur within a volume of material which contains a mechanism of deformation. In such cases, the capacity of the structure to withstand thermal loading is limited by a variation of the maximum thermal stress at a material point of 2σsub(γ) where σsub(γ) is a suitably defined yield stress. This situation seems to be the most typical problem of the Liquid Metal Fast Reactor and the ''3Sm'' limit in the ASME III code restriction on secondary stress cannot be exceeded if ratchetting is to be prevented

Ratchetting behavior of primary heat transport (PHT) piping material SA-333 carbon steel subjected to cyclic loads at room temperature

International Nuclear Information System (INIS)

Kulkarni, S.; Desai, Y.M.; Kant, T.; Reddy, G.R.; Gupta, C.; Chakravarthy, J.K.

2004-01-01

Ratchetting behavior of SA-333 Gr. 6 carbon steel used as primary heat transport (PHT) piping material has been investigated with three constitutive models proposed by Armstrong-Frederick, Chaboche and Ohno-Wang involving different hardening rules. Performance of the above mentioned models have been evaluated for a broad set of uniaxial and biaxial loading histories. The uniaxial ratchetting simulations have been performed for a range of stress ratios (R) by imposing different stress amplitudes and mean stress conditions. Numerical simulations indicated significant ratchetting and opening of hysteresis loop for negative stress ratio with constant mean stress. Application of cyclic stress without mean stress (R = -1.0) has been observed to produce negligible ratchet-strain accumulation in the material. Simulation under the biaxial stress condition was based on modeling of an internally pressurized thin walled pipe subjected to cyclic bending load. Numerical results have been validated with the experiments as per simulation conditions. All three models have been found to predict the observed accumulation of circumferential strain with increasing number of cycles. However, the Armstrong Frederick (A-F) model was found to be inadequate in simulating the ratchetting response for both uniaxial as well as biaxial loading cases. The A-F model actually over-predicted the ratchetting strain in comparison with the experimental strain values. On the other hand, results obtained with the Chaboche and the Ohno-Wang models for both the uniaxial as well as biaxial loading histories have been observed to closely simulate the experimental results. The Ohno-Wang model resulted in better simulation for the presents sets of experimental results in comparison with the Chaboche model. It can be concluded that the Ohno-Wang model suited well compared to the Chaboche model for above sets of uniaxial and biaxial loading histories. (authors)

Microfabricated ratchet structures for concentrating and patterning motile bacterial cells

International Nuclear Information System (INIS)

Kim, Sang Yub; Lee, Eun Se; Lee, Ho Jae; Lee, Se Yeon; Lee, Sung Kuk; Kim, Taesung

2010-01-01

We present a novel microfabricated concentrator for Escherichia coli that can be a stand-alone and self-contained microfluidic device because it utilizes the motility of cells. First of all, we characterize the motility of E. coli cells and various ratcheting structures that can guide cells to move in a desired direction in straight and circular channels. Then, we combine these ratcheting microstructures with the intrinsic tendency of cells to swim on the right side in microchannels to enhance the concentration rates up to 180 fold until the concentrators are fully filled with cells. Furthermore, we demonstrate that cells can be positioned and concentrated with a constant spacing distance on a surface, allowing spatial patterning of motile cells. These results can be applied to biosorption or biosensor devices that are powered by motile cells because they can be highly concentrated without any external mechanical and electrical energy sources. Hence, we believe that the concentrator design holds considerable potential to be applied for concentrating and patterning other motile microbes and providing a versatile structure for motility study of bacterial cells.

Size of silicon strip sensor from 6 inch wafer (right) compared to that from a 4 inch wafer (left).

CERN Multimedia

Honma, Alan

1999-01-01

Silicon strip sensors made from 6 inch wafers will allow for much larger surface area coverage at a reduced cost per unit surface area. A prototype sensor of size 8cm x 11cm made by Hamamatsu from a 6 inch wafer is shown next to a traditional 6cm x 6cm sensor from a 4 inch wafer.

Vortex ratchet effect in a niobium film with spacing-graded density

Czech Academy of Sciences Publication Activity Database

Wu, T.C.; Horng, L.; Wu, J.C.; Cao, R.; Koláček, Jan; Yang, T.-J.

2007-01-01

Roč. 102, č. 3 (2007), 033918/1-033918/4 ISSN 0021-8979 R&D Projects: GA ČR GA202/05/0173 Institutional research plan: CEZ:AV0Z10100521 Keywords : vortex ratchet effect * niobium film Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.171, year: 2007

Incremental elongation or ratchetting - Experimental tests and practical method of analysis (on stainless steel 304L and 306L)

International Nuclear Information System (INIS)

Cousseran, Pierre; Lebey, Jacques; Roche, Roland; Clement, Gerard; Moulin, Didier.

1980-12-01

Ratchetting, or incremental elongation can be considered as a creep enhancement when cyclic deformations are added to a primary constant load. Under examination, it appears that theoretical models proposed till now do not fit correctly the actual behavior of materials. From experimental tests results performed in Saclay, a simplified method for prevention of ratcheting is proposed. A validation was made by using experimental data from various sources [fr

The impact of wire caliber on ERCP outcomes: a multicenter randomized controlled trial of 0.025-inch and 0.035-inch guidewires.

Science.gov (United States)

Bassan, Milan S; Sundaralingam, Praka; Fanning, Scott B; Lau, James; Menon, Jayaram; Ong, Evan; Rerknimitr, Rungsun; Seo, Dong-Wan; Teo, Eng Kiong; Wang, Hsiu-Po; Reddy, D Nageshwar; Goh, Khean Lee; Bourke, Michael J

2018-06-01

Wire-guided biliary cannulation has been demonstrated to improve cannulation rates and reduce post-ERCP pancreatitis (PEP), but the impact of wire caliber has not been studied. This study compares successful cannulation rates and ERCP adverse events by using a 0.025-inch and 0.035-inch guidewire. A randomized, single blinded, prospective, multicenter trial at 9 high-volume tertiary-care referral centers in the Asia-Pacific region was performed. Patients with an intact papilla and conventional anatomy who did not have malignancy in the head of the pancreas or ampulla and were undergoing ERCP were recruited. ERCP was performed by using a standardized cannulation algorithm, and patients were randomized to either a 0.025-inch or 0.035-inch guidewire. The primary outcomes of the study were successful wire-guided cannulation and the incidence of PEP. Overall successful cannulation and ERCP adverse events also were studied. A total of 710 patients were enrolled in the study. The primary wire-guided biliary cannulation rate was similar in 0.025-inch and 0.035-inch wire groups (80.7% vs 80.3%; P = .90). The rate of PEP between the 0.025-inch and the 0.035-inch wire groups did not differ significantly (7.8% vs 9.3%; P = .51). No differences were noted in secondary outcomes. Similar rates of successful cannulation and PEP were demonstrated in the use of 0.025-inch and 0.035-inch guidewires. (Clinical trial registration number: NCT01408264.). Copyright © 2018. Published by Elsevier Inc.

Collective coordinates theory for discrete soliton ratchets in the sine-Gordon model

Science.gov (United States)

Sánchez-Rey, Bernardo; Quintero, Niurka R.; Cuevas-Maraver, Jesús; Alejo, Miguel A.

2014-10-01

A collective coordinate theory is developed for soliton ratchets in the damped discrete sine-Gordon model driven by a biharmonic force. An ansatz with two collective coordinates, namely the center and the width of the soliton, is assumed as an approximated solution of the discrete nonlinear equation. The dynamical equations of these two collective coordinates, obtained by means of the generalized travelling wave method, explain the mechanism underlying the soliton ratchet and capture qualitatively all the main features of this phenomenon. The numerical simulation of these equations accounts for the existence of a nonzero depinning threshold, the nonsinusoidal behavior of the average velocity as a function of the relative phase between the harmonics of the driver, the nonmonotonic dependence of the average velocity on the damping, and the existence of nontransporting regimes beyond the depinning threshold. In particular, it provides a good description of the intriguing and complex pattern of subspaces corresponding to different dynamical regimes in parameter space.

Two-way communication between SecY and SecA suggests a Brownian ratchet mechanism for protein translocation.

Science.gov (United States)

Allen, William John; Corey, Robin Adam; Oatley, Peter; Sessions, Richard Barry; Baldwin, Steve A; Radford, Sheena E; Tuma, Roman; Collinson, Ian

2016-05-16

The essential process of protein secretion is achieved by the ubiquitous Sec machinery. In prokaryotes, the drive for translocation comes from ATP hydrolysis by the cytosolic motor-protein SecA, in concert with the proton motive force (PMF). However, the mechanism through which ATP hydrolysis by SecA is coupled to directional movement through SecYEG is unclear. Here, we combine all-atom molecular dynamics (MD) simulations with single molecule FRET and biochemical assays. We show that ATP binding by SecA causes opening of the SecY-channel at long range, while substrates at the SecY-channel entrance feed back to regulate nucleotide exchange by SecA. This two-way communication suggests a new, unifying 'Brownian ratchet' mechanism, whereby ATP binding and hydrolysis bias the direction of polypeptide diffusion. The model represents a solution to the problem of transporting inherently variable substrates such as polypeptides, and may underlie mechanisms of other motors that translocate proteins and nucleic acids.

Numerical convergence in simulations of multiaxial ratcheting with directional distortional hardening

Czech Academy of Sciences Publication Activity Database

Welling, CH.A.; Marek, René; Feigenbaum, H. P.; Dafalias, Y.F.; Plešek, Jiří; Hrubý, Zbyněk; Parma, Slavomír

2017-01-01

Roč. 126, November (2017), s. 105-121 ISSN 0020-7683 R&D Projects: GA MŠk(CZ) EF15_003/0000493; GA MŠk LH14018 Keywords : plastic ity * yield * ratcheting * yield surface distortion * directional distortional hardening Subject RIV: JG - Metallurgy OBOR OECD: Materials engineering Impact factor: 2.760, year: 2016 http://www.sciencedirect.com/science/article/pii/S0020768317303499

Thermally driven ratchet motion of a skyrmion microcrystal and topological magnon Hall effect

NARCIS (Netherlands)

Mochizuki, M.; Yu, X.Z.; Seki, S.; Kanazawa, N.; Koshibae, W.; Zang, J.; Mostovoy, M.; Tokura, Y.; Nagaosa, N.

2014-01-01

Spontaneously emergent chirality is an issue of fundamental importance across the natural sciences. It has been argued that a unidirectional (chiral) rotation of a mechanical ratchet is forbidden in thermal equilibrium, but becomes possible in systems out of equilibrium. Here we report our finding

Clonal interference and Muller's ratchet in spatial habitats

International Nuclear Information System (INIS)

Otwinowski, Jakub; Krug, Joachim

2014-01-01

Competition between independently arising beneficial mutations is enhanced in spatial populations due to the linear rather than exponential growth of clones. Recent theoretical studies have pointed out that the resulting fitness dynamics is analogous to a surface growth process, where new layers nucleate and spread stochastically, leading to the build up of scale-invariant roughness. This scenario differs qualitatively from the standard view of adaptation in that the speed of adaptation becomes independent of population size while the fitness variance does not. Here we exploit recent progress in the understanding of surface growth processes to obtain precise predictions for the universal, non-Gaussian shape of the fitness distribution for one-dimensional habitats, which are verified by simulations. When the mutations are deleterious rather than beneficial the problem becomes a spatial version of Muller's ratchet. In contrast to the case of well-mixed populations, the rate of fitness decline remains finite even in the limit of an infinite habitat, provided the ratio U d /s 2 between the deleterious mutation rate and the square of the (negative) selection coefficient is sufficiently large. Using, again, an analogy to surface growth models we show that the transition between the stationary and the moving state of the ratchet is governed by directed percolation. (paper)

Analytical investigation of the applicability of simplified ratchetting and creep-fatigue rules to a nozzle-to-sphere geometry

International Nuclear Information System (INIS)

Gwaltney, R.C.

1982-01-01

This paper presents an analysis of a nozzle-to-spherical-shell attachment and explores the applicability of simplified ratchetting and creep-fatigue rules to this attachment. A five-cycle inelastic analysis and creep-fatigue damage evaluation was carried out on this component. An elastic analysis also was done to provide input parameters required to apply the various rules and procedures of simplified analysis methods. Ten lines, or critical sections, were chosen for postprocessing to determine the ratchetting strain and creep-fatigue damage at both the inside and outside surfaces. At many of the 20 surface points analyzed, the inelastic analysis results did not develop a constant or decreasing pattern for the incremental strain or damage even after 5 cycles were analyzed. Failure to develop a constant or decreasing pattern was especially prevalent for creep damage. The results of the detailed inelastic analyses at the ten critical sections are compared with the results of elastic evaluations of ratchetting and creep-fatigue damage calculated according to American Society of Mechanical Engineers Boiler and Pressure Vessel Code Case N-47-13

A three dimensional elastoplastic cyclic constitutive law with a semi discrete variable and a ratchetting stress

International Nuclear Information System (INIS)

Geyer, P.; Proix, J.M.; Jayet-Gendrot, S.; Schoenberger, P.; Taheri, S.

1995-01-01

The study of cyclic elastoplastic constitutive law is, at the moment, focused on non proportional loadings, but for uniaxial loadings some problems remain, as for example the ability for a law to describe simultaneously ratcheting (constant increment of strain) in non symmetrical ones. We propose a law with a discrete memory variable, the plastic strain at the last unloading, and a ratchetting stress which, in addition to previous phenomena, describes the other hand the choice of all macroscopic variables is justified by a microscopic analysis. The extension to 3D situations of this law is proposed. The discrete nature of the memory leads to discontinuity problems for some loading paths, a modification is then proposed which uses a differential evolution law. For large enough uniaxial cycles, the uniaxial law is nevertheless recovered. An incremental form of he implicit evolution problem is given, and we describe the implementation of this model in the Code Aster a thermomechanical structural software using the f.e.m. developed at Electricite de France. For a 316 stainless steel we present comparisons between experiments and numerical results in uniaxial and biaxial ratchetting and non proportional strain controlled test (circular, square, stair loading). (authors). 13 refs., 10 figs

Cyclic creep, mechanical ratchetting and amplitude history dependence of modified 9Cr-1Mo steel and evaluation of unified constitutive models

International Nuclear Information System (INIS)

Tanaka, Eiichi; Yamada, Hiroshi

1993-01-01

The purpose of the present paper is to elucidate inelastic behavior of modified 9Cr-1Mo steel as a candidate material for the next-generation fast breeder reactor and to provide the information for the formulation of a unified constitutive model. For this purpose, cyclic creep, mechanical ratchetting and amplitude history dependence of cyclic hardening were first examined at 550degC. As a result, systematic cyclic creep and mechanical ratchetting behavior were observed under various loading conditions, and little amplitude history dependence was found. Then these results were simulated by three unified constitutive models, i.e. the Chaboche, Bodner-Partom and modified Chaboche models. The simulated results show that these models cannot describe the cyclic creep and mechanical ratchetting behavior with high accuracy, but succeed in describing the inelastic behavior of amplitude variation experiments. (author)

8-inch IBM floppy disk

CERN Multimedia

1971-01-01

The 8-inch floppy disk was a magnetic storage disk for the data introduced commercially by IBM in 1971. It was designed by an IBM team as an inexpensive way to load data into the IBM System / 370. Plus it was a read-only bare disk containing 80 KB of data. The first read-write version was introduced in 1972 by Memorex and could contain 175 KB on 50 tracks (with 8 sectors per track). Other improvements have led to various coatings and increased capacities. Finally, it was surpassed by the mini diskette of 5.25 inches introduced in 1976.

Current-driven domain wall motion based memory devices: Application to a ratchet ferromagnetic strip

Science.gov (United States)

Sánchez-Tejerina, Luis; Martínez, Eduardo; Raposo, Víctor; Alejos, Óscar

2018-04-01

Ratchet memories, where perpendicular magnetocristalline anisotropy is tailored so as to precisely control the magnetic transitions, has been recently proven to be a feasible device to store and manipulate data bits. For such devices, it has been shown that the current-driven regime of domain walls can improve their performances with respect to the field-driven one. However, the relaxing time required by the traveling domain walls constitutes a certain drawback if the former regime is considered, since it results in longer device latencies. In order to speed up the bit shifting procedure, it is demonstrated here that the application of a current of inverse polarity during the DW relaxing time may reduce such latencies. The reverse current must be sufficiently high as to drive the DW to the equilibrium position faster than the anisotropy slope itself, but with an amplitude sufficiently low as to avoid DW backward shifting. Alternatively, it is possible to use such a reverse current to increase the proper range of operation for a given relaxing time, i.e., the pair of values of the current amplitude and pulse time that ensures single DW jumps for a certain latency time.

Ratchetting and creep-fatigue evaluation for nozzle-to-cylinder intersection

International Nuclear Information System (INIS)

Barsoum, R.S.; Loomis, R.W.; Stewart, B.D.

1976-01-01

The study is part of an analytical investigation on the applicability of the simplified ratchetting and creep-fatigue rules to LMFBR component geometry. Both the detailed inelastic rules and the simplified elastic rules are applied to the results obtained from a three-dimensional finite element analysis of the nozzle-to-cylinder intersection. The results of both evaluations are compared at several locations on the surface, and an assessment of the degree of conservatism of the simplified methods is discussed

83-inch cyclotron research program. Final report

International Nuclear Information System (INIS)

Parkinson, W.C.

1983-07-01

In June of 1960 the US Atomic Energy Commission authorized the construction of a modern variable energy cyclotron facility at The University of Michigan to be used for research in nuclear spectroscopy. The Legislature of the State of Michigan made available funds for construction of a building to house the 83-inch cyclotron and auxiliary equipment as well as the University's remodeled 42-inch cyclotron. The research program centered around the 83-inch cyclotron was funded by the AEC and its successors, the Energy Research and Development Administration (ERDA) and the Department of Energy (DOE), from September 1964 through March 1977. The program represented a continuation of the research effort using the 42-inch cyclotron facility which had been supported continuously by the AEC since February 1950. This final report to DOE briefly describes the research facility, the research program, and highlights the principal accomplishments of the effort. It begins with a historical note to place this effort within the context of nuclear physics research in the Department of Physics of the University of Michigan

Entropic Ratchet transport of interacting active Brownian particles

Energy Technology Data Exchange (ETDEWEB)

Ai, Bao-Quan, E-mail: aibq@hotmail.com [Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, 510006 Guangzhou (China); He, Ya-Feng [College of Physics Science and Technology, Hebei University, 071002 Baoding (China); Zhong, Wei-Rong, E-mail: wrzhong@jnu.edu.cn [Department of Physics and Siyuan Laboratory, College of Science and Engineering, Jinan University, 510632 Guangzhou (China)

2014-11-21

Directed transport of interacting active (self-propelled) Brownian particles is numerically investigated in confined geometries (entropic barriers). The self-propelled velocity can break thermodynamical equilibrium and induce the directed transport. It is found that the interaction between active particles can greatly affect the ratchet transport. For attractive particles, on increasing the interaction strength, the average velocity first decreases to its minima, then increases, and finally decreases to zero. For repulsive particles, when the interaction is very weak, there exists a critical interaction at which the average velocity is minimal, nearly tends to zero, however, for the strong interaction, the average velocity is independent of the interaction.

Entropic Ratchet transport of interacting active Brownian particles

International Nuclear Information System (INIS)

Ai, Bao-Quan; He, Ya-Feng; Zhong, Wei-Rong

2014-01-01

Directed transport of interacting active (self-propelled) Brownian particles is numerically investigated in confined geometries (entropic barriers). The self-propelled velocity can break thermodynamical equilibrium and induce the directed transport. It is found that the interaction between active particles can greatly affect the ratchet transport. For attractive particles, on increasing the interaction strength, the average velocity first decreases to its minima, then increases, and finally decreases to zero. For repulsive particles, when the interaction is very weak, there exists a critical interaction at which the average velocity is minimal, nearly tends to zero, however, for the strong interaction, the average velocity is independent of the interaction

Ratchet effect for nanoparticle transport in hair follicles.

Science.gov (United States)

Radtke, Matthias; Patzelt, Alexa; Knorr, Fanny; Lademann, Jürgen; Netz, Roland R

2017-07-01

The motion of a single rigid nanoparticle inside a hair follicle is investigated by means of Brownian dynamics simulations. The cuticular hair structure is modeled as a periodic asymmetric ratchet-shaped surface. Induced by oscillating radial hair motion we find directed nanoparticle transport into the hair follicle with maximal velocity at a specific optimal frequency and an optimal particle size. We observe flow reversal when switching from radial to axial oscillatory hair motion. We also study the diffusion behavior and find strongly enhanced diffusion for axial motion with a diffusivity significantly larger than for free diffusion. Copyright © 2016 Elsevier B.V. All rights reserved.

Nonlinear piping damping and response predictions

International Nuclear Information System (INIS)

Severud, L.K.; Weiner, E.O.; Lindquist, M.R.; Anderson, M.J.; Wagner, S.E.

1986-10-01

The high level dynamic testing of four prototypic piping systems, used to provide benchmarks for analytical prediction comparisons, is overviewed. The size of pipe tested ranged from one-inch to six-inches in diameter and consisted of carbon steel or stainless steel material. Failure of the tested systems included progressive gross deformation or some combination of ratchetting-fatigue. Pretest failure predictions and post test comparisons using simplified elastic and elasto-plastic methods are presented. Detailed non-linear inelastic analyses are also shown, along with a typical ratchet-fatigue failure calculation. A simplified method for calculating modal equivalent viscous damping for snubbers and plastic hinges is also described. Conclusions are made regarding the applicability of the various analytical failure predictive methods and recommendations are made for future analytic and test efforts

Controlling heat transport and flow structures in thermal turbulence using ratchet surfaces

Science.gov (United States)

Sun, Chao; Jiang, Hechuan; Zhu, Xiaojue; Mathai, Varghese; Verzicco, Roberto; Lohse, Detlef

2017-11-01

In this combined experimental and numerical study on thermally driven turbulence in a rectangular cell, the global heat transport and the coherent flow structures are controlled with an asymmetric ratchet-like roughness on the top and bottom plates. We show that, by means of symmetry breaking due to the presence of the ratchet structures on the conducting plates, the orientation of the Large Scale Circulation Roll (LSCR) can be locked to a preferred direction even when the cell is perfectly leveled out. By introducing a small tilt to the system, we show that the LSCR orientation can be tuned and controlled. The two different orientations of LSCR give two quite different heat transport efficiencies, indicating that heat transport is sensitive to the LSCR direction over the asymmetric roughness structure. Through analysis of the dynamics of thermal plume emissions and the orientation of the LSCR over the asymmetric structure, we provide a physical explanation for these findings. This work is financially supported by the Natural Science Foundation of China under Grant No. 11672156, the Dutch Foundation for Fundamental Research on Matter (FOM), the Dutch Technology Foundation (STW) and a VIDI Grant.

Can vocal conditioning trigger a semiotic ratchet in marmosets?

Directory of Open Access Journals (Sweden)

Hjalmar Kosmos Turesson

2015-10-01

Full Text Available The complexity of human communication has often been taken as evidence that our language reflects a true evolutionary leap, bearing little resemblance to any other animal communication system. The putative uniqueness of the human language poses serious evolutionary and ethological challenges to a rational explanation of human communication. Here we review ethological, anatomical, molecular and computational results across several species to set boundaries for these challenges. Results from animal behavior, cognitive psychology, neurobiology, and semiotics indicate that human language shares multiple features with other primate communication systems, such as specialized brain circuits for sensorimotor processing, the capability for indexical (pointing and symbolic (referential signaling, the importance of shared intentionality for associative learning, affective conditioning and parental scaffolding of vocal production. The most substantial differences lie in the higher human capacity for symbolic compositionality, fast vertical transmission of new symbols across generations, and irreversible accumulation of novel adaptive behaviors (cultural ratchet. We hypothesize that increasingly-complex vocal conditioning of an appropriate animal model may be sufficient to trigger a semiotic ratchet, evidenced by progressive sign complexification, as spontaneous contact calls become indexes, then symbols and finally arguments (strings of symbols. To test this hypothesis, we outline a series of conditioning experiments in the common marmoset (Callithrix jacchus. The experiments are designed to probe the limits of vocal communication in a prosocial, highly vocal primate 35 million years far from the human lineage, so as to shed light on the mechanisms of semiotic complexification and cultural transmission, and serve as a naturalistic behavioral setting for the investigation of language disorders.

Can vocal conditioning trigger a semiotic ratchet in marmosets?

Science.gov (United States)

Turesson, Hjalmar K; Ribeiro, Sidarta

2015-01-01

The complexity of human communication has often been taken as evidence that our language reflects a true evolutionary leap, bearing little resemblance to any other animal communication system. The putative uniqueness of the human language poses serious evolutionary and ethological challenges to a rational explanation of human communication. Here we review ethological, anatomical, molecular, and computational results across several species to set boundaries for these challenges. Results from animal behavior, cognitive psychology, neurobiology, and semiotics indicate that human language shares multiple features with other primate communication systems, such as specialized brain circuits for sensorimotor processing, the capability for indexical (pointing) and symbolic (referential) signaling, the importance of shared intentionality for associative learning, affective conditioning and parental scaffolding of vocal production. The most substantial differences lie in the higher human capacity for symbolic compositionality, fast vertical transmission of new symbols across generations, and irreversible accumulation of novel adaptive behaviors (cultural ratchet). We hypothesize that increasingly-complex vocal conditioning of an appropriate animal model may be sufficient to trigger a semiotic ratchet, evidenced by progressive sign complexification, as spontaneous contact calls become indexes, then symbols and finally arguments (strings of symbols). To test this hypothesis, we outline a series of conditioning experiments in the common marmoset (Callithrix jacchus). The experiments are designed to probe the limits of vocal communication in a prosocial, highly vocal primate 35 million years far from the human lineage, so as to shed light on the mechanisms of semiotic complexification and cultural transmission, and serve as a naturalistic behavioral setting for the investigation of language disorders.

30 GHz monolithic balanced mixers using an ion-implanted FET-compatible 3-inch GaAs wafer process technology

Science.gov (United States)

Bauhahn, P.; Contolatis, A.; Sokolov, V.; Chao, C.

1986-01-01

An all ion-implanted Schottky barrier mixer diode which has a cutoff frequency greater than 1000 GHz has been developed. This new device is planar and FET-compatible and employs a projection lithography 3-inch wafer process. A Ka-band monolithic balanced mixer based on this device has been designed, fabricated and tested. A conversion loss of 8 dB has been measured with a LO drive of 10 dBm at 30 GHz.

Current Reversal Due to Coupling Between Asymmetrical Driving Force and Ratchet Potential

International Nuclear Information System (INIS)

Ai Baoquan; Xie Huizhang; Liu Lianggang

2006-01-01

Transport of a Brownian particle moving in a periodic potential is investigated in the presence of an asymmetric unbiased external force. The asymmetry of the external force and the asymmetry of the potential are the two ways of inducing a net current. It is found that the competition of the spatial asymmetry of potential with the temporal asymmetry of the external force leads to the phenomena like current reversal. The competition between the two opposite driving factors is a necessary but not a sufficient condition for current reversals.

Magnetic quantum ratchet effect in Si-MOSFETs

International Nuclear Information System (INIS)

Ganichev, S D; Karch, J; Kamann, J; Tarasenko, S A; Kvon, Z D

2014-01-01

We report on the observation of magnetic quantum ratchet effect in metal-oxide-semiconductor field-effect-transistors on silicon surface (Si-MOSFETs). We show that the excitation of an unbiased transistor by ac electric field of terahertz radiation at normal incidence leads to a direct electric current between the source and drain contacts if the transistor is subjected to an in-plane magnetic field. The current rises linearly with the magnetic field strength and quadratically with the ac electric field amplitude. It depends on the polarization state of the ac field and can be induced by both linearly and circularly polarized radiation. We present the quasi-classical and quantum theories of the observed effect and show that the current originates from the Lorentz force acting upon carriers in asymmetric inversion channels of the transistors. (paper)

SAFT 4{1/2} inch nickel hydrogen battery cells

Energy Technology Data Exchange (ETDEWEB)

Duquesne, D.; Lacout, B.; Sennet, A. [SAFT Advanced Batteries, Poitiers (France)

1995-12-31

SAFT Advanced Batteries has now produced over 400 high capacity 4{1/2} inch Nickel Hydrogen Battery Cells for flight programs. The 4.5 inch diameter, rabbit-ear cell design is designed to provide the anticipated energy required at the lowest practical weight. SAFT has incorporated into the design of the dry-powder nickel electrode, truly hermetic ceramic to metal seals, qualified terminal feedthroughs, high reliability mechanical design, composite pure platinum negative electrode, and zircar separator, plus more than 25 years experience in aerospace nickel cell technology, resulting in a 4{1/2} inch configuration with the 3{1/2} inch cell design carryover heritage. General performance requirements for GEO missions that SAFT cells meet are 15 years in orbit lifetime, 80% DOD, low mass to energy ratios, and flexible capacity by modifying number of electrodes in the stack. This design is qualified for geostationary orbits based on SAFT`s 3{1/2} inch qualification heritage, design verification, and cycling performed by customer Space Systems/LORAL in support of the INTELSAT VIIA and N-STAR flight programs.

Many-Body Quantum Chaos and Entanglement in a Quantum Ratchet

Science.gov (United States)

Valdez, Marc Andrew; Shchedrin, Gavriil; Heimsoth, Martin; Creffield, Charles E.; Sols, Fernando; Carr, Lincoln D.

2018-06-01

We uncover signatures of quantum chaos in the many-body dynamics of a Bose-Einstein condensate-based quantum ratchet in a toroidal trap. We propose measures including entanglement, condensate depletion, and spreading over a fixed basis in many-body Hilbert space, which quantitatively identify the region in which quantum chaotic many-body dynamics occurs, where random matrix theory is limited or inaccessible. With these tools, we show that many-body quantum chaos is neither highly entangled nor delocalized in the Hilbert space, contrary to conventionally expected signatures of quantum chaos.

Quantitative Magnetic Separation of Particles and Cells Using Gradient Magnetic Ratcheting.

Science.gov (United States)

Murray, Coleman; Pao, Edward; Tseng, Peter; Aftab, Shayan; Kulkarni, Rajan; Rettig, Matthew; Di Carlo, Dino

2016-04-13

Extraction of rare target cells from biosamples is enabling for life science research. Traditional rare cell separation techniques, such as magnetic activated cell sorting, are robust but perform coarse, qualitative separations based on surface antigen expression. A quantitative magnetic separation technology is reported using high-force magnetic ratcheting over arrays of magnetically soft micropillars with gradient spacing, and the system is used to separate and concentrate magnetic beads based on iron oxide content (IOC) and cells based on surface expression. The system consists of a microchip of permalloy micropillar arrays with increasing lateral pitch and a mechatronic device to generate a cycling magnetic field. Particles with higher IOC separate and equilibrate along the miropillar array at larger pitches. A semi-analytical model is developed that predicts behavior for particles and cells. Using the system, LNCaP cells are separated based on the bound quantity of 1 μm anti-epithelial cell adhesion molecule (EpCAM) particles as a metric for expression. The ratcheting cytometry system is able to resolve a ±13 bound particle differential, successfully distinguishing LNCaP from PC3 populations based on EpCAM expression, correlating with flow cytometry analysis. As a proof-of-concept, EpCAM-labeled cells from patient blood are isolated with 74% purity, demonstrating potential toward a quantitative magnetic separation instrument. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CERN Library | Roy Calne presents: "The Ratchet of Science - Curiosity killed the cat" | 26 October

CERN Multimedia

CERN Library

2015-01-01

Sir Roy Calne will discuss his most recent book: “The Ratchet of Science - Curiosity killed the cat. Can human nature cope with the rapid and accelerated advances of science?”   Monday, 26 October - 4.30 p.m. CERN Filtration plant, Room 222-R-001 There is a limited number of seats. Please register here. The book’s premise is that huge scientific advances throughout history occur in spurts or “ratchets”. It reflects on the good and the evil consequences of discoveries. Due to the worrying nature of human beings, each ratchet in our knowledge is too often accompanied by dangerous applications. Knowledge, once established by a reliable scientific method, cannot be unlearned. The cat is out of the bag and the curiosity may kill the cat – so to speak. Professor Roy Calne illustrates this with the example of the young physicist known to all at CERN: Lise Meitner, who discovered and named nucle...

Simplified design rule for ratcheting analysis

International Nuclear Information System (INIS)

Cousseran, P.; Clement, G.; Lebey, J.; Roche, R.L.

1982-07-01

Ratcheting in the creep range is the magnification of primary stress effects caused by cyclic straining. Computation results do not agree with experimental results due to the complexity of the real material behavior. From the results of experimental tests a design rule based on the concept of effective primary stress Psub(eff) is proposed. The effective primary stress is a fictitious primary stress giving the same effect that the real loading i.e. the same effect that the combination of an applied primary stress P and a cyclic straining quoted by the range Qsub(R) of secondary stress variation. Determination of an upper bound value of Psub(eff) is made with the help of an efficiency diagram. More precisely the efficiency diagram include a curve giving a conservative value of an efficiency index V = P/Psub(eff) as a function of the secondarity quotient SQ = Qsub(R)/P. Finally limitation of Psub(eff) intensity is discussed in regard with the current practice

Modelling of ratchetting with the Chaboche elastoplastic model modified by Burlet and Cailletaud; Modelisation des phenomenes de deformation progressive par le modele elastoplastique de Chaboche modifie par Burlet et Cailletaud

Energy Technology Data Exchange (ETDEWEB)

Geyer, P

1994-01-01

A fine modelling of the material`s behaviour can be necessary to study the mechanical strength of nuclear power plant`s components under cyclic loads. The modelling of cyclic plasticity made great progress during the past 20 years. Ratchetting is one of the last phenomena for which numerical models have to be improved. We give in this document a state of the art report on research in this field. We notably show the basically different character of ratchetting in uniaxial and biaxial loading tests, usually distinguished as 1D and 2D ratchetting. On the basis of this overview, we selected the kinematic hardening formulation proposed by Burlet and Cailletaud, which we coupled with the Chaboche elastoplastic model with two non linear kinematic hardening variables to improve the modelling of 2D ratchetting. We use the experimental results on the austenitic steel 316L at 20 and 300 deg C under uniaxial loadings (low cycle fatigue) and biaxial loadings (traction-torsion) to study the new model capabilities. We get a good modelling of ratchetting in biaxial loadings. The model has been installed in the ASTER code under the name of UBRLET. It now has to be qualified by component analysis calculations. (author). 25 refs., 30 figs., 11 tabs., 3 annexes.

Monitoring microstructural evolution of alloy 617 with non-linear acoustics for remaining useful life prediction; multiaxial creep-fatigue and creep-ratcheting

International Nuclear Information System (INIS)

Lissenden, Cliff; Hassan, Tasnin; Rangari, Vijaya

2014-01-01

The research built upon a prior investigation to develop a unified constitutive model for design-@by-@analysis of the intermediate heat exchanger (IHX) for a very high temperature reactor (VHTR) design of next generation nuclear plants (NGNPs). Model development requires a set of failure data from complex mechanical experiments to characterize the material behavior. Therefore uniaxial and multiaxial creep-@fatigue and creep-@ratcheting tests were conducted on the nickel base Alloy 617 at 850 and 950°C. The time dependence of material behavior, and the interaction of time dependent behavior (e.g., creep) with ratcheting, which is an increase in the cyclic mean strain under load-@controlled cycling, are major concerns for NGNP design. This research project aimed at characterizing the microstructure evolution mechanisms activated in Alloy 617 by mechanical loading and dwell times at elevated temperature. The acoustic harmonic generation method was researched for microstructural characterization. It is a nonlinear acoustics method with excellent potential for nondestructive evaluation, and even online continuous monitoring once high temperature sensors become available. It is unique because it has the ability to quantitatively characterize microstructural features well before macroscale defects (e.g., cracks) form. The nonlinear acoustics beta parameter was shown to correlate with microstructural evolution using a systematic approach to handle the complexity of multiaxial creep-@fatigue and creep-@ratcheting deformation. Mechanical testing was conducted to provide a full spectrum of data for: thermal aging, tensile creep, uniaxial fatigue, uniaxial creep-@fatigue, uniaxial creep-ratcheting, multiaxial creep-fatigue, and multiaxial creep-@ratcheting. Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), and Optical Microscopy were conducted to correlate the beta parameter with individual microstructure mechanisms. We researched application of the

Development of 52 inches last stage blade for steam turbines

International Nuclear Information System (INIS)

Suzuki, Atsuhide; Hisa, Shoichi; Nagao, Shinichiro; Ogata, Hisao

1986-01-01

The last stage blades of steam turbines are the important component controlling the power output and performance of plants. In order to realize a unit of large capacity and high efficiency, the proper exhaust area and the last stage blades having good performance are indispensable. Toshiba Corp. has completed the development of the 52 inch last stage blades for 1500 and 1800 rpm steam turbines. The 52 inch last stage blades are the longest in the world, which have the annular exhaust area nearly 1.5 times as much as that of 41 inch blades used for 1100 MW, 1500 rpm turbines in nuclear power stations. By adopting these 52 inch blades, the large capacity nuclear power plants up to 1800 MW can be economically constructed, the rate of heat consumption of 1350 MW plants is improved by 3 ∼ 4 % as compared with 41 inch blades, and in the plants up to 1100 MW, LP turbines can be reduced from three sets to two. The features of 52 inch blades, the flow pattern and blade form design, the structural strength analysis and the erosion withstanding property, and the verification by the rotation test of the actual blades, the performance test using a test turbine, the vibration analysis of the actually loaded blades and the analysis of wet steam behavior are reported. (Kako, I.)

Towards Computing Ratcheting and Training in Superconducting Magnets

International Nuclear Information System (INIS)

Ferracin, Paolo; Caspi, Shlomo; Lietzke, A.F.

2007-01-01

The Superconducting Magnet Group at Lawrence Berkeley National Laboratory (LBNL) has been developing 3D finite element models to predict the behavior of high field Nb 3 Sn superconducting magnets. The models track the coil response during assembly, cool-down, and excitation, with particular interest on displacements when frictional forces arise. As Lorentz forces were cycled, irreversible displacements were computed and compared with strain gauge measurements. Additional analysis was done on the local frictional energy released during magnet excitation, and the resulting temperature rise. Magnet quenching and training was correlated to the level of energy release during such mechanical displacements under frictional forces. We report in this paper the computational results of the ratcheting process, the impact of friction, and the path-dependent energy release leading to a computed magnet training curve

Experimental analysis of ratchetting in elbows

International Nuclear Information System (INIS)

Acker, D.; Touboul, F.; Brouard, D.

1991-01-01

Despite of their apparent simplicity, elbows or curved tubes are one of the most tested and analyzed structures to the last years when a large effort has been done by CEA in the framework of the European Structural Integrity Working Group in order to reassess the RCC-MR (1985) piping design rules for elbows and straight parts (TOUBOUL (1988-1989)). It is impossible to mention all the authors and an extensive bibliography has been done by BENDJEDIDIA (1987). But nobody in our knowledge has taken care in experimental validation of design rules against ratcheting. With such objectives, an experimental test program has been performed at CEA, in order to appraise the design methods based on shakedown model like 3 S m rule used by ASME section III (1989) in USA or RCC-M (1988) in FRANCE, or based on the efficiency Diagram used by the french design code for Fast Breeder reactors RCC-MR (1985). The first results were published by M. BENDJEDIDIA (1987). They have been completed by additional tests and improved by a better material characterisation

Hydrodynamic interactions induce movement against an external load in a ratchet dimer Brownian motor.

Science.gov (United States)

Fornés, José A

2010-01-15

We use the Brownian dynamics with hydrodynamic interactions simulation in order to describe the movement of a elastically coupled dimer Brownian motor in a ratchet potential. The only external forces considered in our system were the load, the random thermal noise and an unbiased thermal fluctuation. For a given set of parameters we observe direct movement against the load force if hydrodynamic interactions were considered.

Risk assessment of K Basin twelve-inch and four-inch drain valve failure from a postulated seismic initiating event

Energy Technology Data Exchange (ETDEWEB)

MORGAN, R.G.

1999-06-23

The Spent Nuclear Fuel (SNF) Project will transfer metallic SNF from the Hanford 105 K-East and 105 K-West Basins to safe interim storage in the Canister Storage Building in the 200 Area. The initial basis for design, fabrication, installation, and operation of the fuel removal systems was that the basin leak rate which could result from a postulated accident condition would not be excessive relative to reasonable recovery operations. However, an additional potential K Basin water leak path is through the K Basin drain valves. Three twelve-inch drain valves are located in the main basin bays along the north wall. Five four-inch drain valves are located in the north and south loadout pits (NLOP and SLOP), the weasel pit, the technical viewing pit, and the discharge chute pit. The sumps containing the valves are filled with concrete which covers the drain valve body. Visual observations indicate that only the valve's bonnet and stem are exposed above the basin concrete floor for the twelve-inch drain valve and that much less of the valve's bonnet and stem are exposed above the basin concrete floor for the five four-inch drain valves. It was recognized, however, that damage of the drain valve bonnet or stem during a seismic initiating event could provide a potential K Basin water leak path. The objectives of this analysis are to: (1) evaluate the likelihood of damaging the three twelve-inch drain valves located along the north wall of the main basin and the five four-inch drain valves located in the pits from a seismic initiating event, and (2) determine the likelihood of exceeding a specific consequence (initial leak rate) from a damaged valve. The analysis process is a risk-based uncertainty analysis where each variable is modeled using available information and engineering judgement. The uncertainty associated with each variable is represented by a probability distribution (probability density function). Uncertainty exists because of the inherent

Modified Feynman ratchet with velocity-dependent fluctuations

Directory of Open Access Journals (Sweden)

Jack Denur

2004-03-01

Full Text Available Abstract: The randomness of Brownian motion at thermodynamic equilibrium can be spontaneously broken by velocity-dependence of fluctuations, i.e., by dependence of values or probability distributions of fluctuating properties on Brownian-motional velocity. Such randomness-breaking can spontaneously obtain via interaction between Brownian-motional Doppler effects --- which manifest the required velocity-dependence --- and system geometrical asymmetry. A non random walk is thereby spontaneously superposed on Brownian motion, resulting in a systematic net drift velocity despite thermodynamic equilibrium. The time evolution of this systematic net drift velocity --- and of velocity probability density, force, and power output --- is derived for a velocity-dependent modification of Feynman's ratchet. We show that said spontaneous randomness-breaking, and consequent systematic net drift velocity, imply: bias from the Maxwellian of the system's velocity probability density, the force that tends to accelerate it, and its power output. Maximization, especially of power output, is discussed. Uncompensated decreases in total entropy, challenging the second law of thermodynamics, are thereby implied.

Nanoscale magnetic ratchets based on shape anisotropy

Science.gov (United States)

Cui, Jizhai; Keller, Scott M.; Liang, Cheng-Yen; Carman, Gregory P.; Lynch, Christopher S.

2017-02-01

Controlling magnetization using piezoelectric strain through the magnetoelectric effect offers several orders of magnitude reduction in energy consumption for spintronic applications. However strain is a uniaxial effect and, unlike directional magnetic field or spin-polarized current, cannot induce a full 180° reorientation of the magnetization vector when acting alone. We have engineered novel ‘peanut’ and ‘cat-eye’ shaped nanomagnets on piezoelectric substrates that undergo repeated deterministic 180° magnetization rotations in response to individual electric-field-induced strain pulses by breaking the uniaxial symmetry using shape anisotropy. This behavior can be likened to a magnetic ratchet, advancing magnetization clockwise with each piezostrain trigger. The results were validated using micromagnetics implemented in a multiphysics finite elements code to simulate the engineered spatial and temporal magnetic behavior. The engineering principles start from a target device function and proceed to the identification of shapes that produce the desired function. This approach opens a broad design space for next generation magnetoelectric spintronic devices.

Preparatory Study of Photomultiplier Tubes of 10-inch and 3-inch Diameter for KM3NeT Underwater Neutrino Telescope

International Nuclear Information System (INIS)

Aiello, S.; Giordano, V.; Leonora, E.

2015-01-01

Large area photomultipliers are widely used in neutrino and astro-particle detectors to measure Cherenkov light in media like water or ice. The key element of these detectors are the so-called 'optical module', which consists of a photodetector enclosed in a transparent pressure-resistant container to protect it and ensure good light transmission. KM3NeT collaboration aims to construct an underwater 'hybrid' neutrino telescope by using two models detection unit. The 'tower' detection unit will be composed of large area 10-inch photomultipliers tube enclosed into 13-inch glass vessel sphere. In the 'string' detection unit instead, the light detector will be the 'digital optical module' (DOM) a glass vessel of 17-inch with 31 photomultipliers of 3- inch diameter looking upwards and downwards. The choice of two different kinds of photomultipliers, obliges us to investigate their main characteristics. Noise pulses at the anode of each photomultiplier strongly affect the performance of the detector. A large study was conducted on noise pulses of large area photomultipliers, considering time and charge distributions of dark pulses, pre-pulses, delayed pulses, and after-pulses. The contribution to noise pulses due to the presence of the external glass vessels was also studied. Moreover the presence of the Earth's magnetic field should modify quantities like gain and transit time spread in photomultipliers and we will deeply investigate on this. (authors)

Monitoring microstructural evolution of alloy 617 with non-linear acoustics for remaining useful life prediction; multiaxial creep-fatigue and creep-ratcheting

Energy Technology Data Exchange (ETDEWEB)

Lissenden, Cliff [Pennsylvania State Univ., State College, PA (United States); Hassan, Tasnin [North Carolina State Univ., Raleigh, NC (United States); Rangari, Vijaya [Tuskegee Univ., Tuskegee, AL (United States)

2014-10-30

The research built upon a prior investigation to develop a unified constitutive model for design-­by-­analysis of the intermediate heat exchanger (IHX) for a very high temperature reactor (VHTR) design of next generation nuclear plants (NGNPs). Model development requires a set of failure data from complex mechanical experiments to characterize the material behavior. Therefore uniaxial and multiaxial creep-­fatigue and creep-­ratcheting tests were conducted on the nickel-­base Alloy 617 at 850 and 950°C. The time dependence of material behavior, and the interaction of time dependent behavior (e.g., creep) with ratcheting, which is an increase in the cyclic mean strain under load-­controlled cycling, are major concerns for NGNP design. This research project aimed at characterizing the microstructure evolution mechanisms activated in Alloy 617 by mechanical loading and dwell times at elevated temperature. The acoustic harmonic generation method was researched for microstructural characterization. It is a nonlinear acoustics method with excellent potential for nondestructive evaluation, and even online continuous monitoring once high temperature sensors become available. It is unique because it has the ability to quantitatively characterize microstructural features well before macroscale defects (e.g., cracks) form. The nonlinear acoustics beta parameter was shown to correlate with microstructural evolution using a systematic approach to handle the complexity of multiaxial creep-­fatigue and creep-­ratcheting deformation. Mechanical testing was conducted to provide a full spectrum of data for: thermal aging, tensile creep, uniaxial fatigue, uniaxial creep-­fatigue, uniaxial creep-ratcheting, multiaxial creep-fatigue, and multiaxial creep-­ratcheting. Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), and Optical Microscopy were conducted to correlate the beta parameter with individual microstructure mechanisms. We researched

How does a scanning ribosomal particle move along the 5'-untranslated region of eukaryotic mRNA? Brownian Ratchet model.

Science.gov (United States)

Spirin, Alexander S

2009-11-17

A model of the ATP-dependent unidirectional movement of the 43S ribosomal initiation complex (=40S ribosomal subunit + eIF1 + eIF1A + eIF2.GTP.Met-tRNA(i) + eIF3) during scanning of the 5'-untranslated region of eukaryotic mRNA is proposed. The model is based on the principles of molecular Brownian ratchet machines and explains several enigmatic data concerning the scanning complex. In this model, the one-dimensional diffusion of the ribosomal initiation complex along the mRNA chain is rectified into the net-unidirectional 5'-to-3' movement by the Feynman ratchet-and-pawl mechanism. The proposed mechanism is organized by the heterotrimeric protein eIF4F (=eIF4A + eIF4E + eIF4G), attached to the scanning ribosomal particle via eIF3, and the RNA-binding protein eIF4B that is postulated to play the role of the pawl. The energy for the useful work of the ratchet-and-pawl mechanism is supplied from ATP hydrolysis induced by the eIF4A subunit: ATP binding and its hydrolysis alternately change the affinities of eIF4A for eIF4B and for mRNA, resulting in the restriction of backward diffusional sliding of the 43S ribosomal complex along the mRNA chain, while stochastic movements ahead are allowed.

Experimental study on uniaxial cyclic ratcheting behavior of 304 stainless steel at room temperature

International Nuclear Information System (INIS)

Yang Xianjie; Gao Qing; Cai Lixun; Liu Yujie

2004-01-01

The cyclic tests for 304 stainless steel with solution heat treatment under uni-axial cyclic straining and stressing were carried out systematically. The effects of the cyclic engineering stress amplitude history with constant mean stress, the mean engineering stress history with constant cyclic stress amplitude and the stress amplitude histories with the specific mean stress increment per cycle on the uni-axial ratcheting deformation behavior were investigated. Some significant results are obtained

Quantum ratchets for periodically kicked cold atoms and Bose-Einstein condensates

Energy Technology Data Exchange (ETDEWEB)

Casati, Giulio [Center for Nonlinear and Complex Systems, Universita degli Studi dell' Insubria and Istituto Nazionale per la Fisica della Materia, Unita di Como, Via Valleggio 11, 22100 Como (Italy); Poletti, Dario [Center for Nonlinear and Complex Systems, Universita degli Studi dell' Insubria and Istituto Nazionale per la Fisica della Materia, Unita di Como, Via Valleggio 11, 22100 Como (Italy)

2007-05-15

We study cold atoms and Bose-Einstein condensates exposed to time-dependent standing waves of light. We first discuss a quantum chaotic dissipative ratchet using the method of quantum trajectories. This system is characterized by directed transport emerging from a quantum strange attractor. We then present a very simple model of directed transport with cold atoms in a pair of periodically flashed optical lattices. Finally we study the dynamics of a dilute Bose-Einstein condensate confined in a toroidal trap and exposed to a pair of periodically flashed optical lattices. We show that the many-body atom-atom interactions, treated within the mean-field approximation, can generate directed transport.

Linear micromechanical stepping drive for pinhole array positioning

International Nuclear Information System (INIS)

Endrödy, Csaba; Mehner, Hannes; Hoffmann, Martin; Grewe, Adrian

2015-01-01

A compact linear micromechanical stepping drive for positioning a 7 × 5.5 mm 2 optical pinhole array is presented. The system features a step size of 13.2 µm and a full displacement range of 200 µm. The electrostatic inch-worm stepping mechanism shows a compact design capable of positioning a payload 50% of its own weight. The stepping drive movement, step sizes and position accuracy are characterized. The actuated pinhole array is integrated in a confocal chromatic hyperspectral imaging system, where coverage of the object plane, and therefore the useful picture data, can be multiplied by 14 in contrast to a non-actuated array. (paper)

Wind-Sculpted Vicinity After Opportunity's Sol 1797 Drive

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings just after driving 111 meters (364 feet) on the 1,797th Martian day, or sol, of Opportunity's surface mission (Feb. 12, 2009). North is at the center; south at both ends. Tracks from the drive recede northward across dark-toned sand ripples in the Meridiani Planum region of Mars. Patches of lighter-toned bedrock are visible on the left and right sides of the image. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). This view is presented as a cylindrical projection with geometric seam correction.

Pendulum as a model system for driven rotation in molecular nanoscale machines

DEFF Research Database (Denmark)

Zolotaryuk, Yaroslav; Christiansen, Peter Leth; Nordén, B.

2000-01-01

We suggest a ratchet mechanism of rotatory (or translatory) motion of a Brownian rotator (or a particle) in a spatially symmetric periodic potential. The asymmetry that drives the ratchet motion is due to a special sequence of activation of catalytic sites arranged in space circularly and periodi...

Thermal ratchetting in pipes subjected to intermittent thermal downshocks at elevated temperatures

International Nuclear Information System (INIS)

Corum, J.M.; Young, H.C.; Grindell, A.G.

1974-01-01

The results of two thermal ratchetting tests on straight sections of pipe are presented. The pipes, each of which was machined from a well-characterized heat of type 304 stainless steel, were subjected to a series of thermal downshocks on their inner surface, followed by sustained periods under an internal pressure loading at a temperature of 1100 0 F. Testing was carried out in a special sodium test facility built for the purpose, and the outer surface strain histories were measured using high-temperature capacitive strain gages. The circumferential strain responses, which typify the inelastic behaviors, are presented. 7 references. (U.S.)

Celiac Disease: Four Inches and Seven Pounds...

Science.gov (United States)

... Disease" Articles Celiac Disease Changes Everything / What is Celiac Disease? / Symptoms, Diagnosis & Treatment / Four Inches and Seven Pounds… / Learning to Live Well with Celiac Disease / Living Gluten-Free Spring 2015 Issue: Volume 10 ...

Wind-Sculpted Vicinity After Opportunity's Sol 1797 Drive (Polar)

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings just after driving 111 meters (364 feet) on the 1,797th Martian day, or sol, of Opportunity's surface mission (Feb. 12, 2009). North is at the center; south at both ends. Tracks from the drive recede northward across dark-toned sand ripples in the Meridiani Planum region of Mars. Patches of lighter-toned bedrock are visible on the left and right sides of the image. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). This view is presented as a polar projection with geometric seam correction.

Wind-Sculpted Vicinity After Opportunity's Sol 1797 Drive (Vertical)

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings just after driving 111 meters (364 feet) on the 1,797th Martian day, or sol, of Opportunity's surface mission (Feb. 12, 2009). North is at the center; south at both ends. Tracks from the drive recede northward across dark-toned sand ripples in the Meridiani Planum region of Mars. Patches of lighter-toned bedrock are visible on the left and right sides of the image. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). This view is presented as a vertical projection with geometric seam correction.

Torque expression of 0.018 and 0.022 inch conventional brackets

NARCIS (Netherlands)

Sifakakis, I.; Pandis, N.; Makou, M.; Eliades, T.; Katsaros, C.; Bourauel, C.

2013-01-01

The aim of this study was to assess the effect of the moments generated with low- and high-torque brackets. Four different bracket prescription-slot combinations of the same bracket type (Mini Diamond(R) Twin) were evaluated: high-torque 0.018 and 0.022 inch and low-torque 0.018 and 0.022 inch.

Shaping Cutter Original Profile for Fine-module Ratchet Teeth Cutting

Science.gov (United States)

Sharkov, O. V.; Koryagin, S. I.; Velikanov, N. L.

2018-03-01

The methods for determining geometric characteristics of a theoretical original profile of the cutter for cutting ratchet teeth with a module of 0.3–1.0 mm are considered in the article. Design models describing the shaping process of cutting edges of cutter teeth are developed. Systems of expressions for determining coordinates of the points of front and back edges of cutter teeth; the workpiece angles of rotation during the cutting process; the minimum cutter radius are received. The basic data when using the proposed technique are: radii of circumferences passing through cavities of cutter teeth and external cut teeth; the gradient angle and length of straight section of the front edge of a cut tooth; angles of rotation of the cutter and the workpiece at the moment of shaping.

Rare beneficial mutations can halt Muller's ratchet

Science.gov (United States)

Balick, Daniel; Goyal, Sidhartha; Jerison, Elizabeth; Neher, Richard; Shraiman, Boris; Desai, Michael

2012-02-01

In viral, bacterial, and other asexual populations, the vast majority of non-neutral mutations are deleterious. This motivates the application of models without beneficial mutations. Here we show that the presence of surprisingly few compensatory mutations halts fitness decay in these models. Production of deleterious mutations is balanced by purifying selection, stabilizing the fitness distribution. However, stochastic vanishing of fitness classes can lead to slow fitness decay (i.e. Muller's ratchet). For weakly deleterious mutations, production overwhelms purification, rapidly decreasing population fitness. We show that when beneficial mutations are introduced, a stable steady state emerges in the form of a dynamic mutation-selection balance. We argue this state is generic for all mutation rates and population sizes, and is reached as an end state as genomes become saturated by either beneficial or deleterious mutations. Assuming all mutations have the same magnitude selective effect, we calculate the fraction of beneficial mutations necessary to maintain the dynamic balance. This may explain the unexpected maintenance of asexual genomes, as in mitochondria, in the presence of selection. This will affect in the statistics of genetic diversity in these populations.

Test procedure for the Master-Lee and the modified Champion four inch hydraulic cutters

International Nuclear Information System (INIS)

Crystal, J.B.

1995-01-01

The Master-Lee and the modified Champion 4 Inch hydraulic cutters are being retested to gather and document information related to the following: determine if the Master-Lee cutters will cut the trunnions of an Aluminum fuel canister and a Stainless Steel fuel canister; determine if the Master-Lee cutters will cut 1 1/2 inch diameter fire hose; determine if the modified Champion 4 inch blade will cut sections of piping; and determine the effectiveness of the centering device for the Champion 4 Inch cutters. Determining the limitations of the hydraulic cutter will aid in the process of debris removal in the K-Basin. Based on a previous test, the cutters were returned to the manufacturer for modifications. The modifications to the Champion 4 Inch Cutter and further testing of the Master-Lee Cutter are the subjects of these feature tests

Am/Cm TTR testing - 3/8-inch glass beads evaluation in CIM5

International Nuclear Information System (INIS)

Witt, D. C.

2000-01-01

To facilitate the procurement and handling of the glass former for Am/Cm vitrification in the F-Canyon MPPF, 1/4 inch and 3/8 inch diameter glass beads were purchased from Corning for evaluation in the 5 inch Cylindrical Induction Melter (CIM5). Prior to evaluating the beads in the CIM5, tests were conducted in the Drain Tube Test Stand (DTTS) with 1/4 inch beads, 3/8 inch beads, and a 50/50 mixture to identify any process concerns. Results of the DTTS tests are summarized in Attachment 1. A somewhat larger volume expansion was experienced in all three DTTS runs as compared to a standard run using cullet. Further testing of the use of glass beads in the CIM5 was requested by the Design Authority as Task 1.02 of Technical Task Request 99-MNSS/SE-006. Since the Technical Task Plan was not yet approved, the completion of this task was conducted under an authorization request approved by the SRTC Laboratory Director, S. Wood. This request is included as Attachment 2

The westward drift of the lithosphere: A tidal ratchet?

Directory of Open Access Journals (Sweden)

A. Carcaterra

2018-03-01

Full Text Available Is the westerly rotation of the lithosphere an ephemeral accidental recent phenomenon or is it a stable process of Earth's geodynamics? The reason why the tidal drag has been questioned as the mechanism determining the lithospheric shift relative to the underlying mantle is the apparent too high viscosity of the asthenosphere. However, plate boundaries asymmetries are a robust indication of the ‘westerly’ decoupling of the entire Earth's outer lithospheric shell and new studies support lower viscosities in the low-velocity layer (LVZ atop the asthenosphere. Since the solid Earth tide oscillation is longer in one side relative to the other due to the contemporaneous Moon's revolution, we demonstrate that a non-linear rheological behavior is expected in the lithosphere mantle interplay. This may provide a sort of ratchet favoring lowering of the LVZ viscosity under shear, allowing decoupling in the LVZ and triggering the westerly motion of the lithosphere relative to the mantle.

The development of 8 inch roll-to-plate nanoimprint lithography (8-R2P-NIL) system

Science.gov (United States)

Lee, Lai Seng; Mohamed, Khairudin; Ooi, Su Guan

2017-07-01

Growth in semiconductor and integrated circuit industry was observed in the past decennium of years for industrial technology which followed Moore's law. The line width of nanostructure to be exposed was influenced by the essential technology of photolithography. Thus, it is crucial to have a low cost and high throughput manufacturing process for nanostructures. Nanoimprint Lithography technique invented by Stephen Y. Chou was considered as major nanolithography process to be used in future integrated circuit and integrated optics. The drawbacks of high imprint pressure, high imprint temperature, air bubbles formation, resist sticking to mold and low throughput of thermal nanoimprint lithography on silicon wafer have yet to be solved. Thus, the objectives of this work is to develop a high throughput, low imprint force, room temperature UV assisted 8 inch roll to plate nanoimprint lithography system capable of imprinting nanostructures on 200 mm silicon wafer using roller imprint with flexible mold. A piece of resist spin coated silicon wafer was placed onto vacuum chuck drives forward by a stepper motor. A quartz roller wrapped with a piece of transparent flexible mold was used as imprint roller. The imprinted nanostructures were cured by 10 W, 365 nm UV LED which situated inside the quartz roller. Heat generated by UV LED was dissipated by micro heat pipe. The flexible mold detaches from imprinted nanostructures in a 'line peeling' pattern and imprint pressure was measured by ultra-thin force sensors. This system has imprinting speed capability ranging from 0.19 mm/s to 5.65 mm/s, equivalent to imprinting capability of 3 to 20 pieces of 8 inch wafers per hour. Speed synchronization between imprint roller and vacuum chuck was achieved by controlling pulse rate supplied to stepper motor which drive the vacuum chuck. The speed different ranging from 2 nm/s to 98 nm/s is achievable. Vacuum chuck height was controlled by stepper motor with displacement of 5 nm/step.

Multiaxial Creep-Fatigue and Creep-Ratcheting Failures of Grade 91 and Haynes 230 Alloys Toward Addressing Design Issues of Gen IV Nuclear Power Plants

Energy Technology Data Exchange (ETDEWEB)

Hassan, Tasnim [North Carolina State Univ., Raleigh, NC (United States); Lissenden, Cliff [Penn State Univ., University Park, PA (United States); Carroll, Laura [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2015-04-01

The proposed research will develop systematic sets of uniaxial and multiaxial experimental data at a very high temperature (850-950°C) for Alloy 617. The loading histories to be prescribed in the experiments will induce creep-fatigue and creep-ratcheting failure mechanisms. These experimental responses will be scrutinized in order to quantify the influences of temperature and creep on fatigue and ratcheting failures. A unified constitutive model (UCM) will be developed and validated against these experimental responses. The improved UCM will be incorporated into the widely used finite element commercial software packages ANSYS. The modified ANSYS will be validated so that it can be used for evaluating the very high temperature ASME-NH design-by-analysis methodology for Alloy 617 and thereby addressing the ASME-NH design code issues.

Multiaxial Creep-Fatigue and Creep-Ratcheting Failures of Grade 91 and Haynes 230 Alloys Toward Addressing Design Issues of Gen IV Nuclear Power Plants

International Nuclear Information System (INIS)

Hassan, Tasnim; Lissenden, Cliff; Carroll, Laura

2015-01-01

The proposed research will develop systematic sets of uniaxial and multiaxial experimental data at a very high temperature (850-950°C) for Alloy 617. The loading histories to be prescribed in the experiments will induce creep-fatigue and creep-ratcheting failure mechanisms. These experimental responses will be scrutinized in order to quantify the influences of temperature and creep on fatigue and ratcheting failures. A unified constitutive model (UCM) will be developed and validated against these experimental responses. The improved UCM will be incorporated into the widely used finite element commercial software packages ANSYS. The modified ANSYS will be validated so that it can be used for evaluating the very high temperature ASME-NH design-by-analysis methodology for Alloy 617 and thereby addressing the ASME-NH design code issues.

Brownian Ratchet Mechanism for Faithful Segregation of Low-Copy-Number Plasmids.

Science.gov (United States)

Hu, Longhua; Vecchiarelli, Anthony G; Mizuuchi, Kiyoshi; Neuman, Keir C; Liu, Jian

2017-04-11

Bacterial plasmids are extrachromosomal DNA that provides selective advantages for bacterial survival. Plasmid partitioning can be remarkably robust. For high-copy-number plasmids, diffusion ensures that both daughter cells inherit plasmids after cell division. In contrast, most low-copy-number plasmids need to be actively partitioned by a conserved tripartite ParA-type system. ParA is an ATPase that binds to chromosomal DNA; ParB is the stimulator of the ParA ATPase and specifically binds to the plasmid at a centromere-like site, parS. ParB stimulation of the ParA ATPase releases ParA from the bacterial chromosome, after which it takes a long time to reset its DNA-binding affinity. We previously demonstrated in vitro that the ParA system can exploit this biochemical asymmetry for directed cargo transport. Multiple ParA-ParB bonds can bridge a parS-coated cargo to a DNA carpet, and they can work collectively as a Brownian ratchet that directs persistent cargo movement with a ParA-depletion zone trailing behind. By extending this model, we suggest that a similar Brownian ratchet mechanism recapitulates the full range of actively segregated plasmid motilities observed in vivo. We demonstrate that plasmid motility is tuned as the replenishment rate of the ParA-depletion zone progressively increases relative to the cargo speed, evolving from diffusion to pole-to-pole oscillation, local excursions, and, finally, immobility. When the plasmid replicates, the daughters largely display motilities similar to that of their mother, except that when the single-focus progenitor is locally excursive, the daughter foci undergo directed segregation. We show that directed segregation maximizes the fidelity of plasmid partition. Given that local excursion and directed segregation are the most commonly observed modes of plasmid motility in vivo, we suggest that the operation of the ParA-type partition system has been shaped by evolution for high fidelity of plasmid segregation

A cyclic constitutive law for metals with a semi-discrete memory variable for description of ratcheting phenomena

International Nuclear Information System (INIS)

Andrieux, S.; Schoenberger, P.; Taheri, S.

1993-01-01

The study of cyclic elastoplastic constitutive laws is, at the moment, focused on non proportional loadings, but for uniaxial loadings some problems remain, as for example the ability for a law to describe simultaneously ratcheting in non symmetrical load-controlled test, elastic and plastic shakedown in symmetrical and non symmetrical ones. We have proposed in a law with a discrete memory variable which, in addition to previous phenomena, describes the cyclic hardening in a pushpull test, and the cyclic softening after overloading. A modified law has been proposed to take into account the dependence of cyclic strain stress curve on the history of loading. The extension to 3D situations of this law is proposed. The discrete nature of the memory leads to discontinuity problems for some loading paths, a modification is then proposed which uses a differential evolution law. For large enough uniaxial cycles, the uniaxial law is nevertheless recovered. In this paper, an incremental form of the implicit evolution problem is given, and we describe the implementation of this model in the Code Aster - a thermomechanical structural software using the finite element method (f.e.m) developed at Electricite de France. Comparison between experiment and numerical results is given for uniaxial ratcheting, non proportional strain controlled test

Opportunity's View After Drive on Sol 1806

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings just after driving 60.86 meters (200 feet) on the 1,806th Martian day, or sol, of Opportunity's surface mission (Feb. 21, 2009). North is at the center; south at both ends. Tracks from the drive extend northward across dark-toned sand ripples and light-toned patches of exposed bedrock in the Meridiani Planum region of Mars. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). Engineers designed the Sol 1806 drive to be driven backwards as a strategy to redistribute lubricant in the rovers wheels. The right-front wheel had been showing signs of increased friction. The rover's position after the Sol 1806 drive was about 2 kilometer (1.2 miles) south southwest of Victoria Crater. Cumulative odometry was 14.74 kilometers (9.16 miles) since landing in January 2004, including 2.96 kilometers (1.84 miles) since climbing out of Victoria Crater on the west side of the crater on Sol 1634 (August 28, 2008). This view is presented as a cylindrical projection with geometric seam correction.

Asymmetric step-like characteristics in a tilted rocking ratchet potential

International Nuclear Information System (INIS)

Lee, A. Khangjune; Lee, Jong-Rim; Lee, K.H.

2012-01-01

The overdamped Langevin dynamics has been employed to study the directional transport of particles driven in a tilted rocking ratchet potential. The system subjected to a constant direct force undergoes an asymmetrical dynamic transition from a static state to a sliding state at two different critical forces that are consistent with the predicted values. When an additional alternating force is applied to the system, the time-averaged velocity shows several steps of equal height as the direct force increases. These steps are similar to the Shapiro steps in an rf-driven Josephson junction, and appear whenever the system's natural frequency given by the direct force matches an integer multiple of the applied frequency. When the alternating force exceeds a certain critical value which can be also estimated for a slow rocking, a directional motion known as the rectification effect occurs even at zero direct force.

Operational maneuvers and pipelines activities repairs for the 32 inches scraper tool recovering

Energy Technology Data Exchange (ETDEWEB)

Valdivia, Jose; Salguero, Luis; Villanueva, Pedro [Compania Operadora del Gas Amazonas, Lima (Peru)

2009-07-01

Transportadora de Gas del Peru and the Compania Operadora de Gas del Amazonas, responsible companies of the transport, operation and maintenance of the pipelines who transport natural gas and natural gas liquids respectively of the Camisea Project - Peru, following the internal policies and the maintenance plan of the pipeline transportation system was planned the activities for the internal pipeline inspection of these activities for 729.3 Km of natural gas pipeline covering diameters of 32 inches, 24 inches and 18 inches. After the first run of the cleaning tool, was scheduled the launch of the dummy scraper (scraper tool) along to the first 210 Km of the 32 inches natural gas pipeline , given changes in elevation along the trace and the low flow of transport. This scraper tool could not reach the final destination. After many series operational maneuvers as venting, creation of differential pressure in valves, the scraper tool only reach the first 75 Km of the trace. After an exhaustive analysis of trending pressure variations, it was concluded that this scraper showed intermittent progress of short durations, concluding that this scraper had not reach the next check point. In this way was decided to conduct operational maneuvers in order to locate, relocated and retrieve the scrapper tool from de 32 inches natural gas pipeline. (author)

Progress in Electron Beam Mastering of 100 Gbit/inch2 Density Disc

Science.gov (United States)

Takeda, Minoru; Furuki, Motohiro; Yamamoto, Masanobu; Shinoda, Masataka; Saito, Kimihiro; Aki, Yuichi; Kawase, Hiroshi; Koizumi, Mitsuru; Miyokawa, Toshiaki; Mutou, Masao; Handa, Nobuo

2004-07-01

We developed an electron beam recorder (EBR) capable of recording master discs under atmospheric conditions using a novel differential pumping head. Using the EBR and optimized fabrication process for Si-etched discs with reactive ion etching (RIE), a bottom signal jitter of 9.6% was obtained from a 36 Gbit/inch2 density disc, readout using a near-field optical pickup with an effective numerical aperture (NA) of 1.85 and a wavelength of 405 nm. We also obtained the eye patterns from a 70 Gbit/inch2 density disc readout using an optical pickup with a 2.05 NA and the same wavelength, and showed almost the same modulation ratio as the simulation value. Moreover, the capability of producing pit patterns corresponding to a 104 Gbit/inch2 density is demonstrated.

Double-temperature ratchet model and current reversal of coupled Brownian motors

Science.gov (United States)

Li, Chen-Pu; Chen, Hong-Bin; Zheng, Zhi-Gang

2017-12-01

On the basis of the transport features and experimental phenomena observed in studies of molecular motors, we propose a double-temperature ratchet model of coupled motors to reveal the dynamical mechanism of cooperative transport of motors with two heads, where the interactions and asynchrony between two motor heads are taken into account. We investigate the collective unidirectional transport of coupled system and find that the direction of motion can be reversed under certain conditions. Reverse motion can be achieved by modulating the coupling strength, coupling free length, and asymmetric coefficient of the periodic potential, which is understood in terms of the effective potential theory. The dependence of the directed current on various parameters is studied systematically. Directed transport of coupled Brownian motors can be manipulated and optimized by adjusting the pulsation period or the phase shift of the pulsation temperature.

Terahertz electric field driven electric currents and ratchet effects in graphene

Energy Technology Data Exchange (ETDEWEB)

Ganichev, Sergey D.; Weiss, Dieter; Eroms, Jonathan [Terahertz Center, University of Regensburg (Germany)

2017-11-15

Terahertz field induced photocurrents in graphene were studied experimentally and by microscopic modeling. Currents were generated by cw and pulsed laser radiation in large area as well as small-size exfoliated graphene samples. We review general symmetry considerations leading to photocurrents depending on linear and circular polarized radiation and then present a number of situations where photocurrents were detected. Starting with the photon drag effect under oblique incidence, we proceed to the photogalvanic effect enhancement in the reststrahlen band of SiC and edge-generated currents in graphene. Ratchet effects were considered for in-plane magnetic fields and a structure inversion asymmetry as well as for graphene with non-symmetric patterned top gates. Lastly, we demonstrate that graphene can be used as a fast, broadband detector of terahertz radiation. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Bright Soil Churned by Spirit's Sol 1861 Drive

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Spirit drove 22.7 meters (74 feet) toward the southwest on the 1,861st Martian day, or sol, of Spirit's mission on Mars (March 28, 2009). After the drive, the rover took this image with its front hazard-avoidance camera, looking back at the tracks from the drive. As usual since losing the use of its right-front wheel in 2006, Spirit drove backwards. The immobile right-front wheel churned up a long stripe of bright soil during this drive. Where Spirit has found such bright soil in the past, subsequent analysis of the composition found concentrations of sulfur or silica that testified to past action of water at the site. When members of the rover team saw the large quantity of bright soil exposed by the Sol 1861 drive, they quickly laid plans to investigate the composition with Spirit's alpha particle X-ray spectrometer. The Sol 1861 drive took the rover past the northwest corner of the low plateau called 'Home Plate,' making progress on a route around the western side of Home Plate. The edge of Home Plate forms the horizon on the right side of this image. Husband Hill is on the horizon on the left side. For scale, the parallel rover wheel tracks are about 1 meter (40 inches) apart. The rover's hazard-avoidance cameras take 'fisheye' wide-angle images.

Ratchetting in the creep range

International Nuclear Information System (INIS)

Ponter, A.R.S.; Cocks, A.C.F.; Clement, G.; Roche, R.; Corradi, L.; Franchi, A.

1985-01-01

This report attempts to present a ''State of the Art'' of this problem from three contracting and complementary points of view which reflect separate traditions within the discipline of structural analysis. Part I gives a brief summary of the essential elements of the three constitutive parts and a set of conclusions and recommendations are then formulated. Part II is an attempt by a group at CEA Saclay, France, to distil from available experimental data a set of rules expressed in terms of the stress classifications of the ASME codes, which will ensure the prevention of excessive creep ratchetting. The resulting stresses to an effective (or reference) stress and the creep assessment is then made in terms of the creep produced by the effective stress. They aim at analytical procedures for LMFBR components that operate in the creep region and are subject to considerable thermal transients. Part III by Ponter and Cocks of the University of Leicester is a theoretical study of the problem using bounding and other approximate techniques. The problem is studied in a sequence of increasingly complex problems commencing with an isothermal structure subjected to constant load and terminating in a structure subjected to arbitrary cyclic thermal loading. The results are expressed in terms of a reference stress derived from a plastic shakedown solution, and a reference history of temperature. These techniques are capable of providing assessment of the creep deformation of a structure when the plastic shakedown properties of the structures are known. The particular circumstances which occur in a LMFBR are emphasized. Part IV by Corradi and Franchi discusses the methods by which finite element solution may be calculated. These are surveyed with particular reference to the numerical problems involved and the relationship between computational procedure and the form of the constitutive equation. 162 refs

Opportunity's View After Drive on Sol 1806 (Polar)

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings just after driving 60.86 meters (200 feet) on the 1,806th Martian day, or sol, of Opportunity's surface mission (Feb. 21, 2009). North is at the center; south at both ends. Tracks from the drive extend northward across dark-toned sand ripples and light-toned patches of exposed bedrock in the Meridiani Planum region of Mars. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). Engineers designed the Sol 1806 drive to be driven backwards as a strategy to redistribute lubricant in the rovers wheels. The right-front wheel had been showing signs of increased friction. The rover's position after the Sol 1806 drive was about 2 kilometer (1.2 miles) south southwest of Victoria Crater. Cumulative odometry was 14.74 kilometers (9.16 miles) since landing in January 2004, including 2.96 kilometers (1.84 miles) since climbing out of Victoria Crater on the west side of the crater on Sol 1634 (August 28, 2008). This view is presented as a polar projection with geometric seam correction.

Opportunity's View After Drive on Sol 1806 (Vertical)

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings just after driving 60.86 meters (200 feet) on the 1,806th Martian day, or sol, of Opportunity's surface mission (Feb. 21, 2009). North is at the center; south at both ends. Tracks from the drive extend northward across dark-toned sand ripples and light-toned patches of exposed bedrock in the Meridiani Planum region of Mars. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). Engineers designed the Sol 1806 drive to be driven backwards as a strategy to redistribute lubricant in the rovers wheels. The right-front wheel had been showing signs of increased friction. The rover's position after the Sol 1806 drive was about 2 kilometer (1.2 miles) south southwest of Victoria Crater. Cumulative odometry was 14.74 kilometers (9.16 miles) since landing in January 2004, including 2.96 kilometers (1.84 miles) since climbing out of Victoria Crater on the west side of the crater on Sol 1634 (August 28, 2008). This view is presented as a vertical projection with geometric seam correction.

Comparison of silicon strip tracker module size using large sensors from 6 inch wafers

CERN Multimedia

Honma, Alan

1999-01-01

Two large silicon strip sensor made from 6 inch wafers are placed next to each other to simulate the size of a CMS outer silicon tracker module. On the left is a prototype 2 sensor CMS inner endcap silicon tracker module made from 4 inch wafers.

Experimental tests on ratchet of 304 austenitic steel, at room temperature

International Nuclear Information System (INIS)

Boulais, Jacques; Brouard, Daniel; Lebey, Jacques; Roche, Roland.

1978-09-01

Most of the studies on ratcheting are theoretical and use very rough constitutive equations for the material behavior (perfect plasticity for instance). Most of the available experimental results concern tests on complex structures, and are difficult to interpret. So there is a need for experimental tests on basic structures easy to use to determine the material characteristics. Tests on thin tubular specimen are very interesting because stress, strain and temperature fields are uniform. The primary stress P is an axial tensile one (dead weight), the secondary stress, with ΔQ range, is due to a cyclic angle controled twist. The incremental elongation is obtained as a function of the number of cycles N for different values of P and ΔQ. Diagrams representing the isocurves of cumulated elongation (for a given number of cycles) as a function of P and ΔQ are shown [fr

Atomistic study of a nanometer-scale pump based on the thermal ratchet concept

DEFF Research Database (Denmark)

Oyarzua, Elton; Walther, J. H.; Zambrano, Harvey

In this study, a novel concept of nanoscale pump fabricated using Carbon Nanotubes (CNTs) is presented. The development of nanofluidic systems provides unprecedented possibilities for the control of biology and chemistry at the molecular level with potential applications in low energy cost devices...... dynamics simulations, we explore the possibility to design thermophoretic pumping devices fabricated of CNTs for water transport in nanoconduits. The design of the nanopumps is based on the concept of the Feynman-Smoluchowski ratchet....... of great interest in nanofluidics. Thermophoresisis the phenomenon observed when a mixture of two or more types of motile objects experience a force induced by a thermal gradient and the different types of objects respond to it differently, inducing a motion and segregation of the objects. Using molecular...

Stochastic Ratcheting on a Funneled Energy Landscape Is Necessary for Highly Efficient Contractility of Actomyosin Force Dipoles

Science.gov (United States)

Komianos, James E.; Papoian, Garegin A.

2018-04-01

Current understanding of how contractility emerges in disordered actomyosin networks of nonmuscle cells is still largely based on the intuition derived from earlier works on muscle contractility. In addition, in disordered networks, passive cross-linkers have been hypothesized to percolate force chains in the network, hence, establishing large-scale connectivity between local contractile clusters. This view, however, largely overlooks the free energy of cross-linker binding at the microscale, which, even in the absence of active fluctuations, provides a thermodynamic drive towards highly overlapping filamentous states. In this work, we use stochastic simulations and mean-field theory to shed light on the dynamics of a single actomyosin force dipole—a pair of antiparallel actin filaments interacting with active myosin II motors and passive cross-linkers. We first show that while passive cross-linking without motor activity can produce significant contraction between a pair of actin filaments, driven by thermodynamic favorability of cross-linker binding, a sharp onset of kinetic arrest exists at large cross-link binding energies, greatly diminishing the effectiveness of this contractility mechanism. Then, when considering an active force dipole containing nonmuscle myosin II, we find that cross-linkers can also serve as a structural ratchet when the motor dissociates stochastically from the actin filaments, resulting in significant force amplification when both molecules are present. Our results provide predictions of how actomyosin force dipoles behave at the molecular level with respect to filament boundary conditions, passive cross-linking, and motor activity, which can explicitly be tested using an optical trapping experiment.

Stochastic Ratcheting on a Funneled Energy Landscape Is Necessary for Highly Efficient Contractility of Actomyosin Force Dipoles

Directory of Open Access Journals (Sweden)

James E. Komianos

2018-04-01

Full Text Available Current understanding of how contractility emerges in disordered actomyosin networks of nonmuscle cells is still largely based on the intuition derived from earlier works on muscle contractility. In addition, in disordered networks, passive cross-linkers have been hypothesized to percolate force chains in the network, hence, establishing large-scale connectivity between local contractile clusters. This view, however, largely overlooks the free energy of cross-linker binding at the microscale, which, even in the absence of active fluctuations, provides a thermodynamic drive towards highly overlapping filamentous states. In this work, we use stochastic simulations and mean-field theory to shed light on the dynamics of a single actomyosin force dipole—a pair of antiparallel actin filaments interacting with active myosin II motors and passive cross-linkers. We first show that while passive cross-linking without motor activity can produce significant contraction between a pair of actin filaments, driven by thermodynamic favorability of cross-linker binding, a sharp onset of kinetic arrest exists at large cross-link binding energies, greatly diminishing the effectiveness of this contractility mechanism. Then, when considering an active force dipole containing nonmuscle myosin II, we find that cross-linkers can also serve as a structural ratchet when the motor dissociates stochastically from the actin filaments, resulting in significant force amplification when both molecules are present. Our results provide predictions of how actomyosin force dipoles behave at the molecular level with respect to filament boundary conditions, passive cross-linking, and motor activity, which can explicitly be tested using an optical trapping experiment.

Opportunity's View After Long Drive on Sol 1770

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings just after driving 104 meters (341 feet) on the 1,770th Martian day, or sol, of Opportunity's surface mission (January 15, 2009). Tracks from the drive extend northward across dark-toned sand ripples and light-toned patches of exposed bedrock in the Meridiani Planum region of Mars. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). Prior to the Sol 1770 drive, Opportunity had driven less than a meter since Sol 1713 (November 17, 2008), while it used the tools on its robotic arm first to examine a meteorite called 'Santorini' during weeks of restricted communication while the sun was nearly in line between Mars and Earth, then to examine bedrock and soil targets near Santorini. The rover's position after the Sol 1770 drive was about 1.1 kilometer (two-thirds of a mile) south southwest of Victoria Crater. Cumulative odometry was 13.72 kilometers (8.53 miles) since landing in January 2004, including 1.94 kilometers (1.21 miles) since climbing out of Victoria Crater on the west side of the crater on Sol 1634 (August 28, 2008). This view is presented as a cylindrical projection with geometric seam correction.

Ductility, strength and hardness relation after prior incremental deformation (ratcheting) of austenitic steel

International Nuclear Information System (INIS)

Kussmaul, K.; Diem, H.K.; Wachter, O.

1993-01-01

Experimental investigations into the stress/strain behavior of the niobium stabilized austenitic material with the German notation X6 CrNiNb 18 10 proved that a limited incrementally applied prior deformation will reduce the total deformation capability only by the amount of the prior deformation. It could especially be determined on the little changes in the reduction of area that the basically ductile deformation behavior will not be changed by the type of the prior loading. There is a correlation between the amount of deformation and the increase in hardness. It is possible to correlate both the changes in hardness and the material properties. In the case of low cycle fatigue tests with alternating temperature an incremental increase in total strain (ratcheting) was noted to depend on the strain range applied

A Simple Method to Measure Nematodes' Propulsive Thrust and the Nematode Ratchet.

Science.gov (United States)

Bau, Haim; Yuan, Jinzhou; Raizen, David

2015-11-01

Since the propulsive thrust of micro organisms provides a more sensitive indicator of the animal's health and response to drugs than motility, a simple, high throughput, direct measurement of the thrust is desired. Taking advantage of the nematode C. elegans being heavier than water, we devised a simple method to determine the propulsive thrust of the animals by monitoring their velocity when swimming along an inclined plane. We find that the swimming velocity is a linear function of the sin of the inclination angle. This method allows us to determine, among other things, the animas' propulsive thrust as a function of genotype, drugs, and age. Furthermore, taking advantage of the animals' inability to swim over a stiff incline, we constructed a sawteeth ratchet-like track that restricts the animals to swim in a predetermined direction. This research was supported, in part, by NIH NIA Grant 5R03AG042690-02.

Opportunity's Surroundings After Sol 1820 Drive

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,820th to 1,822nd Martian days, or sols, of Opportunity's surface mission (March 7 to 9, 2009). South is at the center; north at both ends. The rover had driven 20.6 meters toward the northwest on Sol 1820 before beginning to take the frames in this view. Tracks from that drive recede southwestward. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and small exposures of lighter-toned bedrock. This view is presented as a cylindrical projection with geometric seam correction.

Opportunity's View After Long Drive on Sol 1770 (Vertical)

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings just after driving 104 meters (341 feet) on the 1,770th Martian day, or sol, of Opportunity's surface mission (January 15, 2009). This view is presented as a vertical projection with geometric seam correction. North is at the top. Tracks from the drive extend northward across dark-toned sand ripples and light-toned patches of exposed bedrock in the Meridiani Planum region of Mars. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). Prior to the Sol 1770 drive, Opportunity had driven less than a meter since Sol 1713 (November 17, 2008), while it used the tools on its robotic arm first to examine a meteorite called 'Santorini' during weeks of restricted communication while the sun was nearly in line between Mars and Earth, then to examine bedrock and soil targets near Santorini. The rover's position after the Sol 1770 drive was about 1.1 kilometer (two-thirds of a mile) south southwest of Victoria Crater. Cumulative odometry was 13.72 kilometers (8.53 miles) since landing in January 2004, including 1.94 kilometers (1.21 miles) since climbing out of Victoria Crater on the west side of the crater on Sol 1634 (August 28, 2008).

Opportunity's View After Long Drive on Sol 1770 (Polar)

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings just after driving 104 meters (341 feet) on the 1,770th Martian day, or sol, of Opportunity's surface mission (January 15, 2009). This view is presented as a polar projection with geometric seam correction. North is at the top. Tracks from the drive extend northward across dark-toned sand ripples and light-toned patches of exposed bedrock in the Meridiani Planum region of Mars. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). Prior to the Sol 1770 drive, Opportunity had driven less than a meter since Sol 1713 (November 17, 2008), while it used the tools on its robotic arm first to examine a meteorite called 'Santorini' during weeks of restricted communication while the sun was nearly in line between Mars and Earth, then to examine bedrock and soil targets near Santorini. The rover's position after the Sol 1770 drive was about 1.1 kilometer (two-thirds of a mile) south southwest of Victoria Crater. Cumulative odometry was 13.72 kilometers (8.53 miles) since landing in January 2004, including 1.94 kilometers (1.21 miles) since climbing out of Victoria Crater on the west side of the crater on Sol 1634 (August 28, 2008).

Comparisons of ratchetting analysis methods using RCC-M, RCC-MR and ASME codes

International Nuclear Information System (INIS)

Yang Yu; Cabrillat, M.T.

2005-01-01

The present paper compares the simplified ratcheting analysis methods used in RCC-M, RCC-MR and ASME with some examples. Firstly, comparisons of the methods in RCC-M and efficiency diagram in RCC-MR are investigated. A special method is used to describe these two methods with curves in one coordinate, and the different conservation is demonstrated. RCC-M method is also be interpreted by SR (second ratio) and v (efficiency index) which is used in RCC-MR. Hence, we can easily compare the previous two methods by defining SR as abscissa and v as ordinate and plotting two curves of them. Secondly, comparisons of the efficiency curve in RCC-MR and methods in ASME-NH APPENDIX T are investigated, with significant creep. At last, two practical evaluations are performed to show the comparisons of aforementioned methods. (authors)

Discrete numerical investigation of the ratcheting phenomenon in granular materials

Science.gov (United States)

Calvetti, Francesco; di Prisco, Claudio

2010-10-01

Several relevant geotechnical works, such as railway and road embankments, offshore foundations and vibrating machine foundations, are affected by the progressive accumulation of irreversible settlements. These latter represent the macroscopic evidence of the progressive rearrangement of particles under cycling loading, which is commonly referred to, in the literature, as ratcheting. This phenomenon is well known, but it is quite difficult to describe it by means of an appropriate constitutive model. As a consequence, the evaluation of durability of the aforementioned structures remains an open problem. In this article, the phenomenon will be approached by employing a Distinct Element model capable of describing the evolution of the microstructure induced by cyclic mechanical perturbations. Several analyses are performed in order to stress the influence of both the stress level and loading history on the mechanical response of a numerical model of a sand specimen. The numerical analyses are intended to provide an experimental background for conceiving a simplified macro approach based on generalised plasticity theory. In particular by means of probe test the plastic potential and the hardening parameters will be defined as a function of the current stress state and loading history.

Chaotic Dynamics of a Josephson Junction with a Ratchet Potential and Current-Modulating Damping

Science.gov (United States)

Li, Fei; Li, Wenwu; Xu, Lan

2018-04-01

The chaotic dynamics of a Josephson junction with a ratchet potential and current-modulating damping are studied. Under the first-order approximation, we construct the general solution of the first-order equation whose boundedness condition contains the famous Melnikov chaotic criterion. Based on the general solution, the incomputability and unpredictability of the system's chaotic behavior are discussed. For the case beyond perturbation conditions, the evolution of stroboscopic Poincaré sections shows that the system undergoes a quasi-periodic transition to chaos with an increasing intensity of the rf-current. Through a suitable feedback controlling strategy, the chaos can be effectively suppressed and the intensity of the controller can vary in a large range. It is also found that the current between the two separated superconductors increases monotonously in some specific parameter spaces.

Comparision of Incidental Reflection From Containerized Maintenance/Housekeeping Solutions and One Inch of Water

Energy Technology Data Exchange (ETDEWEB)

Chapman, Bryan Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); MacQuigg, Michael Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wysong, Andrew Russell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-12-15

This document addresses the incidental reflector reactivity worth of containerized maintenance/housekeeping fluids for use in PF-4 at Los Alamos National Laboratory (LANL). The intent of the document is to analyze containerized maintenance/housekeeping fluids which will be analyzed as water that may be present under normal conditions of an operation. The reactivity worth is compared to the reactivity worth due to I-inch of close-fitting 4n water reflection and I-inch of close-fitting radial water reflection. Both have been used to bound incidental reflection by 2-liter bottles in criticality safety evaluations. The conclusion is that, when the maintenance/housekeeping fluids are containerized the reactivity increase from a configuration which is bounding of normal conditions (up to eight bottles modeled with 2-liters of solution at varying diameter) is bound by I-inch of close fitting 4n water relection.

12-inch x-ray image intensifier with thin metal input window

Energy Technology Data Exchange (ETDEWEB)

Obata, Yoshiharu; Anno, Hidero; Harao, Norio [Toshiba Corp., Kawasaki, Kanagawa (Japan)

1982-08-01

Borosilicate glass has been used for X-ray input window of image intensifiers (I.I.) up to now. Now two new types of 12-inch metal I.I., RT12301C and RT12302C, have been developed. They use convex 1-mm aluminum (instead of 5-mm borosilicate glass) for the input window. Adopting a high-performance penta-electronic lens and a new type of light guide CsI film, these intensifiers have greatly improved contrast, quantum detection efficiency (QDE) and resolution capability. In spite of low dosage, image quality equivalent to that in the conventional direct radiograph is obtained through combined use of the new-type 12-inch metal I.I. with 0.3-mm small-focal-spot X-ray tube. Great contribution to digital radiography is expected of this I.I.

A new cellular automaton for signal controlled traffic flow based on driving behaviors

Science.gov (United States)

Wang, Yang; Chen, Yan-Yan

2015-03-01

The complexity of signal controlled traffic largely stems from the various driving behaviors developed in response to the traffic signal. However, the existing models take a few driving behaviors into account and consequently the traffic dynamics has not been completely explored. Therefore, a new cellular automaton model, which incorporates the driving behaviors typically manifesting during the different stages when the vehicles are moving toward a traffic light, is proposed in this paper. Numerical simulations have demonstrated that the proposed model can produce the spontaneous traffic breakdown and the dissolution of the over-saturated traffic phenomena. Furthermore, the simulation results indicate that the slow-to-start behavior and the inch-forward behavior can foster the traffic breakdown. Particularly, it has been discovered that the over-saturated traffic can be revised to be an under-saturated state when the slow-down behavior is activated after the spontaneous breakdown. Finally, the contributions of the driving behaviors on the traffic breakdown have been examined. Project supported by the National Basic Research Program of China (Grand No. 2012CB723303) and the Beijing Committee of Science and Technology, China (Grand No. Z1211000003120100).

Opportunity's Surroundings After Sol 1820 Drive (Polar)

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,820th to 1,822nd Martian days, or sols, of Opportunity's surface mission (March 7 to 9, 2009). This view is presented as a polar projection with geometric seam correction. North is at the top. The rover had driven 20.6 meters toward the northwest on Sol 1820 before beginning to take the frames in this view. Tracks from that drive recede southwestward. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and small exposures of lighter-toned bedrock.

Opportunity's Surroundings After Sol 1820 Drive (Vertical)

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,820th to 1,822nd Martian days, or sols, of Opportunity's surface mission (March 7 to 9, 2009). This view is presented as a vertical projection with geometric seam correction. North is at the top. The rover had driven 20.6 meters toward the northwest on Sol 1820 before beginning to take the frames in this view. Tracks from that drive recede southwestward. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and small exposures of lighter-toned bedrock.

Fabrication of 0.5-inch diameter FBR mixed oxide fuel pellets

International Nuclear Information System (INIS)

Rasmussen, D.E.; Benecke, M.W.; McCord, R.B.

1979-01-01

Large diameter (0.535 inch) mixed oxide fuel pellets for Fast Breeder Reactor application were successfully fabricated by the cold-press-and-sinter technique. Enriched UO 2 , PuO 2 -UO 2 , and PuO 2 -ThO 2 compositions were fabricated into nominally 90% theoretical density pellets for the UO 2 and PuO 2 -UO 2 compositions, and 88% and 93% T.D. for the PuO 2 -ThO 2 compositions. Some processing adjustments were required to achieve satisfactory pellet quality and density. Furnace heating rate was reduced from 200 to 50 0 C/h for the organic binder burnout cycle for the large, 0.535-inch diameter pellets to eliminate pellet cracking during sintering. Additional preslugging steps and die wall lubrication during pressing were used to eliminate pressing cracks in the PuO 2 -ThO 2 pellets

Child seat belt guidelines: Examining the 4 feet 9 inches rule as the standard.

Science.gov (United States)

Morse, Amber M; Aitken, Mary E; Mullins, Samantha H; Miller, Beverly K; Pomtree, Mindy M; Ulloa, Erin M; Montgomery, Jeffrey S; Saylors, Marie E

2017-08-01

Current American Academy of Pediatrics recommendations regarding transition from child safety/booster seat to adult safety belt use indicate that children should be at least 4 feet 9 inches, 8 years old, or 80 pounds. Proper fit in the vehicle seat, assessed with a five-point fit test, should also be met. Although most children reach 4 feet 9 inches around age 8 years, each child and vehicle presents a unique combination; thus a child may not fit appropriately in all vehicle types using only the 4 feet 9 inches requirement. We enrolled children, aged 7 years to 12 years, into our study. Height, weight, and demographic data were obtained. A Child Passenger Safety Technician then performed the five-point fit test in each of a uniform lineup of five vehicles. Data were collected on fit in the standard vehicle seat and also in a booster seat. We set 90% as the threshold proportion of children who meet all criteria for proper fit to validate current recommendations of a height of 4 feet 9 inches. Data were collected on 388 children. The percentage of 90% proper fit was met in the compact car and small sport-utility vehicle (SUV). However, only 80 (77%) of 104 students (p vehicles (large SUVs and trucks). This emphasizes the need for evaluation of fit by a trained personnel and/or development of standard back seat dimensions in all vehicles for maximum safety. Epidemiologic study, level III; Therapeutic study, level V.

Worcester 1 Inch Solenoid-Actuated Gas-Operated VPS System Ball Valve

International Nuclear Information System (INIS)

VAN KATWIJK, C.

2000-01-01

1 inch Gas-operated full-port ball valve incorporates a solenoid and limit switches as integral parts of the actuator. The valve is normally open and fails safe to the closed position. The associated valve position switch is class GS

Wind-Sculpted Vicinity After Opportunity's Sol 1797 Drive (Stereo)

Science.gov (United States)

2009-01-01

[figure removed for brevity, see original site] Left-eye view of a color stereo pair for PIA11820 [figure removed for brevity, see original site] Right-eye view of a color stereo pair for PIA11820 NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this stereo, full-circle view of the rover's surroundings just after driving 111 meters (364 feet) on the 1,797th Martian day, or sol, of Opportunity's surface mission (Feb. 12, 2009). North is at the center; south at both ends. This view is the right-eye member of a stereo pair presented as a cylindrical-perspective projection with geometric seam correction. Tracks from the drive recede northward across dark-toned sand ripples in the Meridiani Planum region of Mars. Patches of lighter-toned bedrock are visible on the left and right sides of the image. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). This view is presented as a cylindrical-perspective projection with geometric seam correction.

Controlling Heat Transport and Flow Structures in Thermal Turbulence Using Ratchet Surfaces

Science.gov (United States)

Jiang, Hechuan; Zhu, Xiaojue; Mathai, Varghese; Verzicco, Roberto; Lohse, Detlef; Sun, Chao

2018-01-01

In this combined experimental and numerical study on thermally driven turbulence in a rectangular cell, the global heat transport and the coherent flow structures are controlled with an asymmetric ratchetlike roughness on the top and bottom plates. We show that, by means of symmetry breaking due to the presence of the ratchet structures on the conducting plates, the orientation of the large scale circulation roll (LSCR) can be locked to a preferred direction even when the cell is perfectly leveled out. By introducing a small tilt to the system, we show that the LSCR orientation can be tuned and controlled. The two different orientations of LSCR give two quite different heat transport efficiencies, indicating that heat transport is sensitive to the LSCR direction over the asymmetric roughness structure. Through a quantitative analysis of the dynamics of thermal plume emissions and the orientation of the LSCR over the asymmetric structure, we provide a physical explanation for these findings. The current work has important implications for passive and active flow control in engineering, biofluid dynamics, and geophysical flows.

Chaotic transport of a matter-wave soliton in a biperiodically driven optical superlattice

International Nuclear Information System (INIS)

Zhou Zheng; Hai Wenhua; Deng Yan; Xie Qiongtao

2012-01-01

Under the effective particle approximation, we study the temporal ratchet effect for chaotic transport of a matter-wave soliton consisting of an attractive Bose–Einstein condensate held in a quasi-one-dimensional symmetric optical superlattice with biperiodic driving. It is known that chaos can substitute for disorder in Anderson’s scenario [Wimberger S, Krug A, Buchleitner A. Phys Rev Lett 2002;89:263601] and only a higher level of disorder can induce Anderson localization for some special systems [Schwartz T, Bartal G, Fishman S, Segev M. Nature 2007;46:52], and a matter-wave soliton can transit to chaos with high or low probability in a high- or low-chaoticity region [Zhu Q, Hai W, Rong S. Phys Rev E 2009;80:016203]. Here we demonstrate that varying the driving phase to break the time reversal symmetry of the system can increase the size of the high-chaoticity region for low- and moderate-frequency regions. Consequently, the parameter region of the exponential spatial localization increases to the same size, and the low-chaoticity and delocalization region, which includes subregions of the ratchet effect and its inverse effect, correspondingly decreases. The positive dependence of the localization on the driving frequency is also revealed. The results indicate that a high-chaoticity region could replace higher disorder and assists in Anderson localization. From the results we suggest a method for controlling directed motion of a matter-wave soliton by adjusting the driving frequency and amplitude to strengthen or suppress, or even reverse, the temporal ratchet effect.

Child seat belt guidelines: Examining the 4 feet 9 inches rule as the standard.

Science.gov (United States)

Morse, Amber M; Aitken, Mary E; Mullins, Samantha H; Miller, Beverly K; Pomtree, Mindy M; Ulloa, Erin M; Montgomery, Jeffrey S; Saylors, Marie E

2017-11-01

Current American Academy of Pediatrics recommendations regarding transition from child safety/booster seat to adult safety belt use indicate that children should be at least 4 feet 9 inches, 8 years old, or 80 pounds. Proper fit in the vehicle seat, assessed with a five-point fit test, should also be met. Although most children reach 4 feet 9 inches around age 8 years, each child and vehicle presents a unique combination; thus a child may not fit appropriately in all vehicle types using only the 4 feet 9 inches requirement. We enrolled children, aged 7 years to 12 years, into our study. Height, weight, and demographic data were obtained. A Child Passenger Safety Technician then performed the five-point fit test in each of a uniform lineup of five vehicles. Data were collected on fit in the standard vehicle seat and also in a booster seat. We set 90% as the threshold proportion of children who meet all criteria for proper fit to validate current recommendations of a height of 4 feet 9 inches. Data were collected on 388 children. The percentage of 90% proper fit was met in the compact car and small sport-utility vehicle (SUV). However, only 80 (77%) of 104 students (p guidelines for an adult seat belt do not meet safety requirements for fit, especially in larger, commonly used vehicles (large SUVs and trucks). This emphasizes the need for evaluation of fit by a trained personnel and/or development of standard back seat dimensions in all vehicles for maximum safety. Epidemiologic level 1.

Project W320 52-inch diameter equipment container load test: Test report

International Nuclear Information System (INIS)

Bellomy, J.R.

1995-01-01

This test report summarizes testing activities and documents the results of the load tests performed on-site and off-site to structural qualify the 52-inch equipment containers designed and fabricated under Project W-320

Worcester 1 Inch Solenoid-Actuated Gas Operated SCHe System Valves

International Nuclear Information System (INIS)

VAN KATWIJK, C.

2000-01-01

1 inch Gas-operated full-port ball valves incorporate a solenoid and limit switches as integral parts of the actuator. These valves are normally open and fail safe to the open position (GOV-1*02 and 1*06 fail closed) to provide a flow path of helium gas to the MCO under helium purge and off-normal conditions when the MCO is isolated

Opportunity's View After Drive on Sol 1806 (Stereo)

Science.gov (United States)

2009-01-01

[figure removed for brevity, see original site] Left-eye view of a color stereo pair for PIA11816 [figure removed for brevity, see original site] Right-eye view of a color stereo pair for PIA11816 NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this stereo, full-circle view of the rover's surroundings just after driving 60.86 meters (200 feet) on the 1,806th Martian day, or sol, of Opportunity's surface mission (Feb. 21, 2009). North is at the center; south at both ends. This view combines images from the left-eye and right-eye sides of the navigation camera. It appears three-dimensional when viewed through red-blue glasses with the red lens on the left. Tracks from the drive extend northward across dark-toned sand ripples and light-toned patches of exposed bedrock in the Meridiani Planum region of Mars. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). Engineers designed the Sol 1806 drive to be driven backwards as a strategy to redistribute lubricant in the rovers wheels. The right-front wheel had been showing signs of increased friction. The rover's position after the Sol 1806 drive was about 2 kilometer (1.2 miles) south southwest of Victoria Crater. Cumulative odometry was 14.74 kilometers (9.16 miles) since landing in January 2004, including 2.96 kilometers (1.84 miles) since climbing out of Victoria Crater on the west side of the crater on Sol 1634 (August 28, 2008). This view is presented as a cylindrical-perspective projection with geometric seam correction.

Health physics challenges involved with opening a "seventeen-inch" concrete waste vault.

Science.gov (United States)

Sullivan, Patrick T; Pizzulli, Michelle

2005-05-01

This paper describes the various activities involved with opening a sealed legacy "Seventeen-inch" concrete vault and the health physics challenges and solutions employed. As part of a legacy waste stream that was removed from the former Hazardous Waste Management Facility at Brookhaven National Laboratory, the "Seventeen-inch" concrete vault labeled 1-95 was moved to the new Waste Management Facility for ultimate disposal. Because the vault contained 239Pu foils with a total activity in excess of the transuranic waste limits, the foils needed to be removed and repackaged for disposal. Conventional diamond wire saws could not be used because of facility constraints, so this project relied mainly on manual techniques. The planning and engineering controls put in place enabled personnel to open the vault and remove the waste while keeping dose as low as reasonably achievable.

Design and Simulation of an Electrothermal Actuator Based Rotational Drive

Science.gov (United States)

Beeson, Sterling; Dallas, Tim

2008-10-01

As a participant in the Micro and Nano Device Engineering (MANDE) Research Experience for Undergraduates program at Texas Tech University, I learned how MEMS devices operate and the limits of their operation. Using specialized AutoCAD-based design software and the ANSYS simulation program, I learned the MEMS fabrication process used at Sandia National Labs, the design limitations of this process, the abilities and drawbacks of micro devices, and finally, I redesigned a MEMS device called the Chevron Torsional Ratcheting Actuator (CTRA). Motion is achieved through electrothermal actuation. The chevron (bent-beam) actuators cause a ratcheting motion on top of a hub-less gear so that as voltage is applied the CTRA spins. The voltage applied needs to be pulsed and the frequency of the pulses determine the angular frequency of the device. The main objective was to design electromechanical structures capable of transforming the electrical signals into mechanical motion without overheating. The design was optimized using finite element analysis in ANSYS allowing multi-physics simulations of our model system.

MLEP-Fail calibration for 1/8 inch thick cast plate of 17-4 steel.

Energy Technology Data Exchange (ETDEWEB)

Corona, Edmundo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2018-02-01

The purpose of the work presented in this memo was to calibrate the Sierra material model Multilinear Elastic-Plastic Hardening Model with Failure (MLEP-Fail) for 1/8 inch thick cast plate of 17-4 steel. The calibration approach is essentially the same as that recently used in a previous memo using data from smooth and notched tensile specimens. The notched specimens were manufactured with three notch radii R = 1=8, 1/32 and 1/64 inches. The dimensions of the smooth and notched specimens are given in the prints in Appendix A. Two cast plates, Plate 3 and Plate 4, with nominally identical properties were considered.

Head-disk interface nanotribology for Tbit/inch2 recording densities: near-contact and contact recording

Science.gov (United States)

Vakis, Antonis I.; Polycarpou, Andreas A.

2010-06-01

In the effort to achieve Tbit/inch2 recording densities, thermal fly-height control (TFC) nanotechnology was developed to effectively reduce the clearance (which is of the order of a few nanometres) at the head-disk interface (HDI) of hard-disk drives. In this work, we present a model of the HDI that can predict the dynamic flying and nanotribological contacting behaviour, allowing for accurate predictions and characterization of the operating regime as a function of TFC actuation. A geometric model for TFC is presented and an improved definition of contact at the interface is developed in the presence of nanoscale topographical roughness and dynamic microwaviness. A new methodology is proposed for the calculation of the nominal area of contact, which affects both near- and at-contact behaviour, while the stiffening of the air bearing force with TFC actuation is also accounted for. Slider behaviour is analysed by quantifying the approach, jump-to-contact, lubricant and solid contact regimes of operation and identifying the critical and optimum TFC actuations. The feasibility of near-contact, light molecularly thin lubricant contact versus solid contact recording is explored under the effect of the interfacial forces and stresses present at the HDI. The clearance and the state of vibrations are analysed and design guidelines are proposed for improved performance.

Head-disk interface nanotribology for Tbit/inch2 recording densities: near-contact and contact recording

International Nuclear Information System (INIS)

Vakis, Antonis I; Polycarpou, Andreas A

2010-01-01

In the effort to achieve Tbit/inch 2 recording densities, thermal fly-height control (TFC) nanotechnology was developed to effectively reduce the clearance (which is of the order of a few nanometres) at the head-disk interface (HDI) of hard-disk drives. In this work, we present a model of the HDI that can predict the dynamic flying and nanotribological contacting behaviour, allowing for accurate predictions and characterization of the operating regime as a function of TFC actuation. A geometric model for TFC is presented and an improved definition of contact at the interface is developed in the presence of nanoscale topographical roughness and dynamic microwaviness. A new methodology is proposed for the calculation of the nominal area of contact, which affects both near- and at-contact behaviour, while the stiffening of the air bearing force with TFC actuation is also accounted for. Slider behaviour is analysed by quantifying the approach, jump-to-contact, lubricant and solid contact regimes of operation and identifying the critical and optimum TFC actuations. The feasibility of near-contact, light molecularly thin lubricant contact versus solid contact recording is explored under the effect of the interfacial forces and stresses present at the HDI. The clearance and the state of vibrations are analysed and design guidelines are proposed for improved performance.

The 52-inch last-stage blades for steam turbines

International Nuclear Information System (INIS)

Suzuki, Atsuhide; Hisa, Shoichi; Nagao, Shin-ichiro; Ogata, Hisao

1986-01-01

The last-stage blades (LSB) of steam turbines are one of the most important components determining the plant's maximum capacity and efficiency. The development of LSBs necessitates high-technology including advanced methods of analyses and verifications as well as ample accumulation of technical data. The 52-inch LSB recently developed by Toshiba has raised nuclear power plant's capacity up to 1,300 ∼ 1,800 MW, has effected compact design of turbine units, and has improved thermal efficiency, keeping high reliability. (author)

Gaussian white noise as a resource for work extraction.

Science.gov (United States)

Dechant, Andreas; Baule, Adrian; Sasa, Shin-Ichi

2017-03-01

We show that uncorrelated Gaussian noise can drive a system out of equilibrium and can serve as a resource from which work can be extracted. We consider an overdamped particle in a periodic potential with an internal degree of freedom and a state-dependent friction, coupled to an equilibrium bath. Applying additional Gaussian white noise drives the system into a nonequilibrium steady state and causes a finite current if the potential is spatially asymmetric. The model thus operates as a Brownian ratchet, whose current we calculate explicitly in three complementary limits. Since the particle current is driven solely by additive Gaussian white noise, this shows that the latter can potentially perform work against an external load. By comparing the extracted power to the energy injection due to the noise, we discuss the efficiency of such a ratchet.

The effect of creep ratchetting on thin shells

International Nuclear Information System (INIS)

Hibbeler, R.C.; Wang, P.Y.

1975-01-01

The behavior of thin shells, in particular, cylindrical and spherical shells, which are subjected to a long-time cyclic thermal gradient is discussed. Like many reactor components (shells) which are subjected to start-up and shut-down conditions, provided the temperature is high enough, the shell will exhibit a progressive growth with each cycle of temperature. This phenomena is often referred to as ratchetting and is caused by inelastic strains developed by creep. Although the thermal stress distribution is biaxial it is possible to represent the material behavior using a simple uniaxial-stress model. Assuming thermal stress interaction occurs, the equations which determine the solution of the strain growth and stress per cycle are presented. The flexibility of the analysis provides a means for including the effects of an arbitrary temperature-cycle time and temperature dependence of material properties. A step temperature variation is considered. During each part of the temperature cycle it is necessary to satisfy the equilibrium and compatibility conditions for the model. At any instant, the total strain will depend upon elastic, thermal, and creep strain components in addition to prior inelastic creep strains accumulated during previous temperature cycles. Accounting for all these conditions, the relations describing the behavior of the material can be determined during an arbitrary jth cycle of temperature. In particular, the cases of material properties are considered which are used for reactor components. Where possible, a closed form solution is given for appropriate values of the creep law exponents n and m. For the general case, an algorithm for the computer-solution to the problem is given. Using the general solution, the analysis appears to offer a suitable compromise between accurate behavior description and analytical complexity

Microscopic analysis of the influence of ratcheting on the evolution of dislocation structures observed in AISI 316L stainless steel during low cycle fatigue

Energy Technology Data Exchange (ETDEWEB)

Facheris, G., E-mail: giacomo.facheris@psi.ch [Laboratory for Nuclear Materials, Nuclear Energy and Safety Research Department, Paul Scherrer Institute, Villigen PSI (Switzerland); Pham, M.-S. [Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); High Temperature Integrity Group, Mechanics for Modelling and Simulation, Swiss Federal Laboratories for Materials Science and Technology, EMPA, Dübendorf (Switzerland); Janssens, K.G.F., E-mail: koen.janssens@psi.ch [Laboratory for Nuclear Materials, Nuclear Energy and Safety Research Department, Paul Scherrer Institute, Villigen PSI (Switzerland); Holdsworth, S.R. [High Temperature Integrity Group, Mechanics for Modelling and Simulation, Swiss Federal Laboratories for Materials Science and Technology, EMPA, Dübendorf (Switzerland)

2013-12-10

When subjected to controlled cyclic deformation, the response of austenitic stainless steel typically involves primary hardening followed by softening, and eventually cyclic stabilization with or without secondary hardening. If a continuously drifting mean strain is superposed to an alternating strain path (i.e. strain controlled ratcheting), the response in terms of mean stress and strain amplitude is significantly different. A series of low cycle fatigue and ratcheting experiments are performed at room temperature on round specimens extracted from a batch of AISI 316L hot rolled plate. The experiments are interrupted at cycle numbers selected to correspond with the different strain controlled cycle response stages. The as-received material and the fatigued specimens are analyzed by means of transmission electron microscopy to characterize the microstructure and its evolution with cyclic loading. The low cycle fatigue experiments, performed to establish a reference point for the zero mean strain loading condition, are in line with observations reported for AISI 316L stainless steel by other authors. The continuously increasing mean strain is found to induce higher dislocation densities in the channels of the evolving microstructure, being responsible for the macroscopically observed additional hardening. The observed polarized dislocation walls at least partially accommodate the continuously drifting mean strain and play a role in the non-zero mean stress response.

Artist autonomy in a digital era: The case of Nine Inch Nails

Directory of Open Access Journals (Sweden)

Steven C. Brown

2012-09-01

Full Text Available A 2009 presentation by Michael Masnick (CEO and founder of insight company Floor64 entitled ‘How Trent Reznor and Nine Inch Nails represent the Future of the Music Business’ brought the success of the business models employed by Reznor in distributing Nine Inch Nails’ music into the spotlight. The present review provides a comprehensive timeline of the band circa 2005-2010, evaluating the success of the distribution methods employed in accordance with Masnick’s (2009 proposed business model of connecting with fans and providing them with a reason to buy. The model is conceptualised in the wider context in which Reznor’s distribution methods take place (including a brief consideration of Radiohead’s much cited pay-what-you- want model, addressing the perceived gaps in the model by exploring the involvement of musical preferences; age and consumer purchasing behavior and fan worship. Implications are discussed concerning the applicability of the model for new and emerging bands.

DEVELOPMENT OF A NINE INCH DIAMETER, MACH 5.5, MONORAIL, ROCKET SLED.

Science.gov (United States)

A nine inch diameter monorail rocket sled was designed, fabricated and tested at Holloman Air Force Base. The vehicle was designed to allow easy...replacement of appendages which were subject to severe aerodynamic heating and/or high wear rates. The monorail vehicle as described was shown to be

The influence of drinking, texting, and eating on simulated driving performance.

Science.gov (United States)

Irwin, Christopher; Monement, Sophie; Desbrow, Ben

2015-01-01

Driving is a complex task and distractions such as using a mobile phone for the purpose of text messaging are known to have a significant impact on driving. Eating and drinking are common forms of distraction that have received less attention in relation to their impact on driving. The aim of this study was to further explore and compare the effects of a variety of distraction tasks (i.e., text messaging, eating, drinking) on simulated driving. Twenty-eight healthy individuals (13 female) participated in a crossover design study involving 3 experimental trials (separated by ≥24 h). In each trial, participants completed a baseline driving task (no distraction) before completing a second driving task involving one of 3 different distraction tasks (drinking 400 mL water, drinking 400 mL water and eating a 6-inch Subway sandwich, drinking 400 mL water and composing 3 text messages). Primary outcome measures of driving consisted of standard deviation of lateral position (SDLP) and reaction time to auditory and visual critical events. Subjective ratings of difficulty in performing the driving tasks were also collected at the end of the study to determine perceptions of distraction difficulty on driving. Driving tasks involving texting and eating were associated with significant impairment in driving performance measures for SDLP compared to baseline driving (46.0 ± 0.08 vs. 41.3 ± 0.06 cm and 44.8 ± 0.10 vs. 41.6 ± 0.07 cm, respectively), number of lane departures compared to baseline driving (10.9 ± 7.8 vs. 7.6 ± 7.1 and 9.4 ± 7.5 vs. 7.1 ± 7.0, respectively), and auditory reaction time compared to baseline driving (922 ± 95 vs. 889 ± 104 ms and 933 ± 101 vs. 901 ± 103 ms, respectively). No difference in SDLP (42.7 ± 0.08 vs. 42.5 ± 0.07 cm), number of lane departures (7.6 ± 7.7 vs. 7.0 ± 6.8), or auditory reaction time (891 ± 98 and 885 ± 89 ms) was observed in the drive involving the drink-only condition compared to the corresponding baseline drive

Quantum ratchets, the orbital Josephson effect, and chaos in Bose-Einstein condensates

Science.gov (United States)

Carr, Lincoln D.; Heimsoth, Martin; Creffield, Charles E.; Sols, Fernando

2014-03-01

In a system of ac-driven condensed bosons we study a new type of Josephson effect occurring between states sharing the same region of space and the same internal atom structure. We first develop a technique to calculate the long-time dynamics of a driven interacting many-body system. For resonant frequencies, this dynamics can be shown to derive from an effective time-independent Hamiltonian which is expressed in terms of standard creation and annihilation operators. Within the subspace of resonant states, and if the undriven states are plane waves, a locally repulsive interaction between bosons translates into an effective attraction. We apply the method to study the effect of interactions on the coherent ratchet current of an asymmetrically driven boson system. We find a wealth of dynamical regimes which includes Rabi oscillations, self-trapping and chaotic behavior. In the latter case, a full quantum many-body calculation deviates from the mean-field results by predicting large quantum fluctuations of the relative particle number. Moreover, we find that chaos and entanglement, as defined by a variety of widely used and accepted measures, are overlapping but distinct notions. Funded by Spanish MINECO, the Ramon y Cajal program (CEC), the Comunidad de Madrid through Grant Microseres, the Heidelberg Center for Quantum Dynamics, and the NSF.

Opportunity's View After Long Drive on Sol 1770 (Stereo)

Science.gov (United States)

2009-01-01

[figure removed for brevity, see original site] Left-eye view of a color stereo pair for PIA11791 [figure removed for brevity, see original site] Right-eye view of a color stereo pair for PIA11791 NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this stereo, full-circle view of the rover's surroundings just after driving 104 meters (341 feet) on the 1,770th Martian day, or sol, of Opportunity's surface mission (January 15, 2009). This view combines images from the left-eye and right-eye sides of the navigation camera. It appears three-dimensional when viewed through red-blue glasses with the red lens on the left. Tracks from the drive extend northward across dark-toned sand ripples and light-toned patches of exposed bedrock in the Meridiani Planum region of Mars. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). Prior to the Sol 1770 drive, Opportunity had driven less than a meter since Sol 1713 (November 17, 2008), while it used the tools on its robotic arm first to examine a meteorite called 'Santorini' during weeks of restricted communication while the sun was nearly in line between Mars and Earth, then to examine bedrock and soil targets near Santorini. The rover's position after the Sol 1770 drive was about 1.1 kilometer (two-thirds of a mile) south southwest of Victoria Crater. Cumulative odometry was 13.72 kilometers (8.53 miles) since landing in January 2004, including 1.94 kilometers (1.21 miles) since climbing out of Victoria Crater on the west side of the crater on Sol 1634 (August 28, 2008). This view is presented as a cylindrical-perspective projection with geometric seam correction.

Concurrent Driving Method with Fast Scan Rate for Large Mutual Capacitance Touch Screens

Directory of Open Access Journals (Sweden)

Mohamed Gamal Ahmed Mohamed

2015-01-01

Full Text Available A novel touch screen control technique is introduced, which scans each frame in two steps of concurrent multichannel driving and differential sensing. The proposed technique substantially increases the scan rate and reduces the ambient noise effectively. It is also extended to a multichip architecture to support excessively large touch screens with great scan rate improvement. The proposed method has been implemented using 0.18 μm CMOS TowerJazz process and tested with FPGA and AFE board connecting a 23-inch touch screen. Experimental results show a scan rate improvement of up to 23.8 times and an SNR improvement of 24.6 dB over the conventional method.

Cryogenic vacuum pumping at the LBL 88-inch cyclotron

International Nuclear Information System (INIS)

Elo, D.; Morris, D.; Clark, D.J.; Gough, R.A.

1978-09-01

A cryogenic vacuum pumping panel has been in operation at the 88-inch cyclotron since 1974. The nude pumping panel is located in the acceleration chamber. The pumping surface consists of tubing cooled to 20 0 K by a closed loop helium refrigeration system. The pumping surfaces are shielded from radiation heat loads and water vapors by liquid nitrogen cooled baffles. The panel was designed for an average pumping speed of 14,000 liters/sec. for air. This approximately tripled the total effective pumping on the acceleration chamber from the existing diffusion pumped system, significantly reducing charge exchange losses of heavy ions during acceleration. Design, installation and performance characteristics are described

Metallurgical Evaluation of the Five-Inch Cylindrical Induction Melter

International Nuclear Information System (INIS)

Imrich, K.J.

2000-01-01

A metallurgical evaluation of the 5-inch cylindrical induction melter (CIM) vessel was performed by the Materials Technology Section to evaluate the metallurgical condition after operating for approximately 375 hours at 1400 to 1500 Degrees Celsius during a 2 year period. Results indicate that wall thinning and significant grain growth occurred in the lower portion of the conical section and the drain tube. No through-wall penetrations were found in the cylindrical and conical sections of the CIM vessel and only one leak site was identified in the drain tube. Failure of the drain tube was associated with a localized over heating and intercrystalline fracture

Interim results: fines recycle testing using the 4-inch diameter primary graphite burner

International Nuclear Information System (INIS)

Palmer, W.B.

1975-05-01

The results of twenty-two HTGR primary burner runs in which graphite fines were recycled pneumatically to the 4-inch diameter pilot-plant primary fluidized-bed burner are described. The result of the tests showed that zero fines accumulation can easily be achieved while operating at plant equivalent burn rates. (U.S.)

Asymmetric ratchet effect for directional transport of fog drops on static and dynamic butterfly wings.

Science.gov (United States)

Liu, Chengcheng; Ju, Jie; Zheng, Yongmei; Jiang, Lei

2014-02-25

Inspired by novel creatures, researchers have developed varieties of fog drop transport systems and made significant contributions to the fields of heat transferring, water collecting, antifogging, and so on. Up to now, most of the efforts in directional fog drop transport have been focused on static surfaces. Considering it is not practical to keep surfaces still all the time in reality, conducting investigations on surfaces that can transport fog drops in both static and dynamic states has become more and more important. Here we report the wings of Morpho deidamia butterflies can directionally transport fog drops in both static and dynamic states. This directional drop transport ability results from the micro/nano ratchet-like structure of butterfly wings: the surface of butterfly wings is composed of overlapped scales, and the scales are covered with porous asymmetric ridges. Influenced by this special structure, fog drops on static wings are transported directionally as a result of the fog drops' asymmetric growth and coalescence. Fog drops on vibrating wings are propelled directionally due to the fog drops' asymmetric dewetting from the wings.

Transport in ratchets with single-file constraint

Indian Academy of Sciences (India)

file diffusion” in the literature. Anomaly in protein molecule diffusion on a cell ... tic media [20]. The rectification effect vanishes in the adiabatically slow modulation limit and optimizes in a driving frequency range. In other related work on flash-.

Stochastic Stokes' Drift, Homogenized Functional Inequalities, and Large Time Behavior of Brownian Ratchets

KAUST Repository

Blanchet, Adrien

2009-01-01

A periodic perturbation of a Gaussian measure modifies the sharp constants in Poincarae and logarithmic Sobolev inequalities in the homogeniz ation limit, that is, when the period of a periodic perturbation converges to zero. We use variational techniques to determine the homogenized constants and get optimal convergence rates toward s equilibrium of the solutions of the perturbed diffusion equations. The study of these sharp constants is motivated by the study of the stochastic Stokes\\' drift. It also applies to Brownian ratchets and molecular motors in biology. We first establish a transport phenomenon. Asymptotically, the center of mass of the solution moves with a constant velocity, which is determined by a doubly periodic problem. In the reference frame attached to the center of mass, the behavior of the solution is governed at large scale by a diffusion with a modified diffusion coefficient. Using the homogenized logarithmic Sobolev inequality, we prove that the solution converges in self-similar variables attached to t he center of mass to a stationary solution of a Fokker-Planck equation modulated by a periodic perturbation with fast oscillations, with an explicit rate. We also give an asymptotic expansion of the traveling diffusion front corresponding to the stochastic Stokes\\' drift with given potential flow. © 2009 Society for Industrial and Applied Mathematics.

Experimental observations on uniaxial whole-life transformation ratchetting and low-cycle stress fatigue of super-elastic NiTi shape memory alloy micro-tubes

Science.gov (United States)

Song, Di; Kang, Guozheng; Kan, Qianhua; Yu, Chao; Zhang, Chuanzeng

2015-07-01

In this work, the low-cycle fatigue failure of super-elastic NiTi shape memory alloy micro-tubes with a wall thickness of 150 μm is investigated by uniaxial stress-controlled cyclic tests at human body temperature 310 K. The effects of mean stress, peak stress, and stress amplitude on the uniaxial whole-life transformation ratchetting and fatigue failure of the NiTi alloy are observed. It is concluded that the fatigue life depends significantly on the stress levels, and the extent of martensite transformation and its reverse play an important role in determining the fatigue life. High peak stress or complete martensite transformation shortens the fatigue life.

Experimental observations on uniaxial whole-life transformation ratchetting and low-cycle stress fatigue of super-elastic NiTi shape memory alloy micro-tubes

International Nuclear Information System (INIS)

Song, Di; Kang, Guozheng; Kan, Qianhua; Yu, Chao; Zhang, Chuanzeng

2015-01-01

In this work, the low-cycle fatigue failure of super-elastic NiTi shape memory alloy micro-tubes with a wall thickness of 150 μm is investigated by uniaxial stress-controlled cyclic tests at human body temperature 310 K. The effects of mean stress, peak stress, and stress amplitude on the uniaxial whole-life transformation ratchetting and fatigue failure of the NiTi alloy are observed. It is concluded that the fatigue life depends significantly on the stress levels, and the extent of martensite transformation and its reverse play an important role in determining the fatigue life. High peak stress or complete martensite transformation shortens the fatigue life. (paper)

Two members of the CERN HPD team present their babies. André Braem (left) holds in his hands a 5-inch glass HPD, while a ceramic HPD for medical applications is shown by Christian Joram. The large detector in the middle is a 10-inch HPD developed for an astrophysics experiment.

CERN Multimedia

Maximilien Brice

2004-01-01

Two members of the CERN HPD team present their babies. André Braem (left) holds in his hands a 5-inch glass HPD, while a ceramic HPD for medical applications is shown by Christian Joram. The large detector in the middle is a 10-inch HPD developed for an astrophysics experiment.

Heat Exchanger Design and Testing for a 6-Inch Rotating Detonation Engine

Science.gov (United States)

2013-03-01

water-cooled rotating detonation engine ( RDE ) run on hydrogen and air. The change in water temperature as it cooled the engine was used to find the...a quick-response resistance temperature detector (RTD) was used in an uncooled RDE of similar dimension to the cooled RDE to estimate the transient...double-checking my design calculations, providing his experience with cooling the 3-inch RDE , and for providing technical expertise in regard to the

Extended driving impairs nocturnal driving performances.

Directory of Open Access Journals (Sweden)

Patricia Sagaspe

Full Text Available Though fatigue and sleepiness at the wheel are well-known risk factors for traffic accidents, many drivers combine extended driving and sleep deprivation. Fatigue-related accidents occur mainly at night but there is no experimental data available to determine if the duration of prior driving affects driving performance at night. Participants drove in 3 nocturnal driving sessions (3-5 am, 1-5 am and 9 pm-5 am on open highway. Fourteen young healthy men (mean age [+/-SD] = 23.4 [+/-1.7] years participated Inappropriate line crossings (ILC in the last hour of driving of each session, sleep variables, self-perceived fatigue and sleepiness were measured. Compared to the short (3-5 am driving session, the incidence rate ratio of inappropriate line crossings increased by 2.6 (95% CI, 1.1 to 6.0; P<.05 for the intermediate (1-5 am driving session and by 4.0 (CI, 1.7 to 9.4; P<.001 for the long (9 pm-5 am driving session. Compared to the reference session (9-10 pm, the incidence rate ratio of inappropriate line crossings were 6.0 (95% CI, 2.3 to 15.5; P<.001, 15.4 (CI, 4.6 to 51.5; P<.001 and 24.3 (CI, 7.4 to 79.5; P<.001, respectively, for the three different durations of driving. Self-rated fatigue and sleepiness scores were both positively correlated to driving impairment in the intermediate and long duration sessions (P<.05 and increased significantly during the nocturnal driving sessions compared to the reference session (P<.01. At night, extended driving impairs driving performances and therefore should be limited.

NO PLIF imaging in the CUBRC 48-inch shock tunnel

Science.gov (United States)

Jiang, N.; Bruzzese, J.; Patton, R.; Sutton, J.; Yentsch, R.; Gaitonde, D. V.; Lempert, W. R.; Miller, J. D.; Meyer, T. R.; Parker, R.; Wadham, T.; Holden, M.; Danehy, P. M.

2012-12-01

Nitric oxide planar laser-induced fluorescence (NO PLIF) imaging is demonstrated at a 10-kHz repetition rate in the Calspan University at Buffalo Research Center's (CUBRC) 48-inch Mach 9 hypervelocity shock tunnel using a pulse burst laser-based high frame rate imaging system. Sequences of up to ten images are obtained internal to a supersonic combustor model, located within the shock tunnel, during a single ~10-millisecond duration run of the ground test facility. Comparison with a CFD simulation shows good overall qualitative agreement in the jet penetration and spreading observed with an average of forty individual PLIF images obtained during several facility runs.

NO PLIF imaging in the CUBRC 48-inch shock tunnel

Energy Technology Data Exchange (ETDEWEB)

Jiang, N.; Bruzzese, J.; Patton, R.; Sutton, J.; Yentsch, R.; Gaitonde, D.V.; Lempert, W.R. [The Ohio State University, Departments of Mechanical and Aerospace Engineering, Columbus, OH (United States); Miller, J.D.; Meyer, T.R. [Iowa State University, Department of Mechanical Engineering, Ames, IA (United States); Parker, R.; Wadham, T.; Holden, M. [CUBRC, Buffalo, NY (United States); Danehy, P.M. [NASA Langley Research Center, Hampton, VA (United States)

2012-12-15

Nitric oxide planar laser-induced fluorescence (NO PLIF) imaging is demonstrated at a 10-kHz repetition rate in the Calspan University at Buffalo Research Center's (CUBRC) 48-inch Mach 9 hypervelocity shock tunnel using a pulse burst laser-based high frame rate imaging system. Sequences of up to ten images are obtained internal to a supersonic combustor model, located within the shock tunnel, during a single {proportional_to}10-millisecond duration run of the ground test facility. Comparison with a CFD simulation shows good overall qualitative agreement in the jet penetration and spreading observed with an average of forty individual PLIF images obtained during several facility runs. (orig.)

Design and RF test result of High Power Hybrid Combiner for Helicon Wave Current Drive in KSTAR Plasmas

Energy Technology Data Exchange (ETDEWEB)

Park, S. Y.; Kim, H. J.; Wi, H. H.; Wang, S. J.; Kwak, J. G. [NFRI, Daejeon (Korea, Republic of)

2016-05-15

200 kW RF power will be injected to plasmas through the traveling wave antenna after combining four klystrons output powers using three hybrid combiners. Each klystron produces 60 kW output at the frequency of 500 MHz. RF power combiners commonly used to divide or combine output powers for various rf and microwave applications. It is divided into several types according to the design type such as Wilkinson combiner, radial and quadrature hybrid combiner. We designed high power hybrid combiners using 6-1/8 inch coaxial line. The power combiner has many advantages such as high isolation, low insertion loss and high power handling capability. In this paper design and rf test results of high power combiners will be described. High power combiners using three coaxial hybrid couplers will be utilized for effectively combining of 500 MHz, 200 kW output powers generated by four klystrons. We have designed, fabricated, and tested a 6-1/8 inch coaxial hybrid combiners at 500 MHz for efficiently off-axis Helicon wave current drive in KSTAR. Simulation and test results of high power coaxial hybrid combiners are good agreement.

Structural reinforcement of a {theta}16 inches tee made during operation with composite material

Energy Technology Data Exchange (ETDEWEB)

Beim, Andre [Tresca Engenharia Ltda., Sao Paulo, SP (Brazil); Vilani, Eduardo Cesar [Rust Engenharia Ltda., Diadema, SP (Brazil)

2009-07-01

An industrial installation went through a turnaround to increase capacity. A tie-in line had to be made for this, and a 16 inches diameter branch was required to be made on an existing 16 inches pipe. The joining of these elements resulted in a 'tee' that was supposed to receive a reinforcement plate. This reinforcement plate was not installed before the plant start-up. Code calculations and a finite element stress analysis showed that reinforcement was necessary. The only viable solution was the application of a composite material reinforcement, designed to substitute the missing reinforcement plate, and reduce the stresses to allowable levels. A new finite element stress analysis was made to determine the required thickness of this reinforcement. The first part of this work shows the results of the finite element stress analysis. Figures with stress contours of the analyses show the results. The second part shows the details of the installation of the reinforcement, which was made during normal operation of the plant. Pictures illustrate the main steps of the installation procedure. (author)

Ion pump as Brownian motor: theory of electroconformational coupling and proof of ratchet mechanism for Na,K-ATPase action

Science.gov (United States)

Tsong, Tian Yow; Chang, Cheng-Hung

2003-04-01

This article reviews some concepts of the Brownian Ratchet which are relevant to our discussion of mechanisms of action of Na,K-ATPase, a universal ion pump and an elemental motor protein of the biological cell. Under wide ranges of ionic compositions it can hydrolyze an ATP and use the γ-phosphorous bond energy of ATP to pump 3 Na + out of, and 2 K + into the cell, both being uphill transport. During the ATP-dependent pump cycle, the enzyme oscillates between E1 and E2 states. Our experiment replaces ATP with externally applied electric field of various waveforms, amplitudes, and frequencies. The field enforced-oscillation, or fluctuation of E1 and E2 states enables the enzyme to harvest energy from the applied field and convert it to the chemical gradient energy of cations. A theory of electroconformational coupling (TEC), which embodies all the essential features of the Brownian Ratchet, successfully simulates these experimental results. Our analysis based on a four-state TEC model indicates that the equilibrium and the rate constants of the transport system define the frequency and the amplitude of the field for the optimal activation. Waveform, frequency, and amplitude are three elements of signal. Thus, electric signal of the ion pump is found by TEC analysis of the experimental data. Electric noise (white) superimposed on an electric signal changes the pump efficiency and produces effects similar to the stochastic resonance reported in other biological systems. The TEC concept is compared with the most commonly used Michaelis-Menten enzyme mechanism (MME) for similarities and differences. Both MME and TEC are catalytic wheels, which recycle the catalyst in each turnover. However, a MME can only catalyze reaction of descending free energy while a TEC enzyme can catalyze reaction of ascending free energy by harvesting needed energy from an off-equilibrium electric noise. The TEC mechanism is shown to be applicable to other biological motors and engines, as

Design of a 18F production system at ORNL 86-inch cyclotron

International Nuclear Information System (INIS)

Shaeffer, M.C.; Barreto, F.; Datesh, J.R.; Goldstein, B.R.

1977-01-01

A target system for the production of 18 F by proton bombardment of H 2 18 O was designed for the ORNL 86-inch cyclotron facility. The system consists of concentric titanium and aluminum cylinders. Oxygen-18-enriched H 2 O circulates through the inner titanium cylinder and through an external heat exchanger with cooling water flowing in the annulus. Yields of 5.0 curies are expected for a 250-μA proton beam current and 24-min irradiation time

Changes in glance behaviour when using a visual eco-driving system - A field study.

Science.gov (United States)

Ahlstrom, Christer; Kircher, Katja

2017-01-01

While in-vehicle eco-driving support systems have the potential to reduce greenhouse gas emissions and save fuel, they may also distract drivers, especially if the system makes use of a visual interface. The objective of this study is to investigate the visual behaviour of drivers interacting with such a system, implemented on a five-inch screen mounted above the middle console. Ten drivers participated in a real-world, on-road driving study where they drove a route nine times (2 pre-baseline drives, 5 treatment drives, 2 post-baseline drives). The route was 96 km long and consisted of rural roads, urban roads and a dual-lane motorway. The results show that drivers look at the system for 5-8% of the time, depending on road type, with a glance duration of about 0.6 s, and with 0.05% long glances (>2s) per kilometre. These figures are comparable to what was found for glances to the speedometer in this study. Glance behaviour away from the windscreen is slightly increased in treatment as compared to pre- and post-baseline, mirror glances decreased in treatment and post-baseline compared to pre-baseline, and speedometer glances increased compared to pre-baseline. The eco-driving support system provided continuous information interspersed with additional advice pop-ups (announced by a beep) and feedback pop-ups (no auditory cue). About 20% of sound initiated advice pop-ups were disregarded, and the remaining cases were usually looked at within the first two seconds. About 40% of the feedback pop-ups were disregarded. The amount of glances to the system immediately before the onset of a pop-up was clearly higher for feedback than for advice. All in all, the eco-driving support system under investigation is not likely to have a strong negative impact on glance behaviour. However, there is room for improvements. We recommend that eco-driving information is integrated with the speedometer, that optional activation of sound alerts for intermittent information is made

Opportunity's Surroundings After Sol 1820 Drive (Stereo)

Science.gov (United States)

2009-01-01

[figure removed for brevity, see original site] Left-eye view of a color stereo pair for PIA11841 [figure removed for brevity, see original site] Right-eye view of a color stereo pair for PIA11841 NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,820th to 1,822nd Martian days, or sols, of Opportunity's surface mission (March 7 to 9, 2009). This view combines images from the left-eye and right-eye sides of the navigation camera. It appears three-dimensional when viewed through red-blue glasses with the red lens on the left. The rover had driven 20.6 meters toward the northwest on Sol 1820 before beginning to take the frames in this view. Tracks from that drive recede southwestward. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and small exposures of lighter-toned bedrock. This view is presented as a cylindrical-perspective projection with geometric seam correction.

Evaluation of 3 Inch SN-219 Failure and S and SX Tank Farm Saltwell Piping

International Nuclear Information System (INIS)

ELSEN, J.J.

2000-01-01

Evaluation of direct buried piping currently in use or designated for future Saltwell pumping in S and SX Farms. Documented evaluation of failed S-103 saltwell pumping transfer line 3 inch SN-219. This evaluation is intended to reflect current status of Saltwell piping, when taken in context with referenced documents

Glaucoma and Driving: On-Road Driving Characteristics

Science.gov (United States)

Wood, Joanne M.; Black, Alex A.; Mallon, Kerry; Thomas, Ravi; Owsley, Cynthia

2016-01-01

Purpose To comprehensively investigate the types of driving errors and locations that are most problematic for older drivers with glaucoma compared to those without glaucoma using a standardized on-road assessment. Methods Participants included 75 drivers with glaucoma (mean = 73.2±6.0 years) with mild to moderate field loss (better-eye MD = -1.21 dB; worse-eye MD = -7.75 dB) and 70 age-matched controls without glaucoma (mean = 72.6 ± 5.0 years). On-road driving performance was assessed in a dual-brake vehicle by an occupational therapist using a standardized scoring system which assessed the types of driving errors and the locations where they were made and the number of critical errors that required an instructor intervention. Driving safety was rated on a 10-point scale. Self-reported driving ability and difficulties were recorded using the Driving Habits Questionnaire. Results Drivers with glaucoma were rated as significantly less safe, made more driving errors, and had almost double the rate of critical errors than those without glaucoma. Driving errors involved lane positioning and planning/approach, and were significantly more likely to occur at traffic lights and yield/give-way intersections. There were few between group differences in self-reported driving ability. Conclusions Older drivers with glaucoma with even mild to moderate field loss exhibit impairments in driving ability, particularly during complex driving situations that involve tactical problems with lane-position, planning ahead and observation. These results, together with the fact that these drivers self-report their driving to be relatively good, reinforce the need for evidence-based on-road assessments for evaluating driving fitness. PMID:27472221

Glaucoma and Driving: On-Road Driving Characteristics.

Directory of Open Access Journals (Sweden)

Joanne M Wood

Full Text Available To comprehensively investigate the types of driving errors and locations that are most problematic for older drivers with glaucoma compared to those without glaucoma using a standardized on-road assessment.Participants included 75 drivers with glaucoma (mean = 73.2±6.0 years with mild to moderate field loss (better-eye MD = -1.21 dB; worse-eye MD = -7.75 dB and 70 age-matched controls without glaucoma (mean = 72.6 ± 5.0 years. On-road driving performance was assessed in a dual-brake vehicle by an occupational therapist using a standardized scoring system which assessed the types of driving errors and the locations where they were made and the number of critical errors that required an instructor intervention. Driving safety was rated on a 10-point scale. Self-reported driving ability and difficulties were recorded using the Driving Habits Questionnaire.Drivers with glaucoma were rated as significantly less safe, made more driving errors, and had almost double the rate of critical errors than those without glaucoma. Driving errors involved lane positioning and planning/approach, and were significantly more likely to occur at traffic lights and yield/give-way intersections. There were few between group differences in self-reported driving ability.Older drivers with glaucoma with even mild to moderate field loss exhibit impairments in driving ability, particularly during complex driving situations that involve tactical problems with lane-position, planning ahead and observation. These results, together with the fact that these drivers self-report their driving to be relatively good, reinforce the need for evidence-based on-road assessments for evaluating driving fitness.

Glaucoma and Driving: On-Road Driving Characteristics.

Science.gov (United States)

Wood, Joanne M; Black, Alex A; Mallon, Kerry; Thomas, Ravi; Owsley, Cynthia

2016-01-01

To comprehensively investigate the types of driving errors and locations that are most problematic for older drivers with glaucoma compared to those without glaucoma using a standardized on-road assessment. Participants included 75 drivers with glaucoma (mean = 73.2±6.0 years) with mild to moderate field loss (better-eye MD = -1.21 dB; worse-eye MD = -7.75 dB) and 70 age-matched controls without glaucoma (mean = 72.6 ± 5.0 years). On-road driving performance was assessed in a dual-brake vehicle by an occupational therapist using a standardized scoring system which assessed the types of driving errors and the locations where they were made and the number of critical errors that required an instructor intervention. Driving safety was rated on a 10-point scale. Self-reported driving ability and difficulties were recorded using the Driving Habits Questionnaire. Drivers with glaucoma were rated as significantly less safe, made more driving errors, and had almost double the rate of critical errors than those without glaucoma. Driving errors involved lane positioning and planning/approach, and were significantly more likely to occur at traffic lights and yield/give-way intersections. There were few between group differences in self-reported driving ability. Older drivers with glaucoma with even mild to moderate field loss exhibit impairments in driving ability, particularly during complex driving situations that involve tactical problems with lane-position, planning ahead and observation. These results, together with the fact that these drivers self-report their driving to be relatively good, reinforce the need for evidence-based on-road assessments for evaluating driving fitness.

A new alignment procedure for the South African Astronomical Observatory's 74-inch telescope

Science.gov (United States)

Crause, Lisa A.; Booth, John A.; Doss, David; Loubser, Egan; O'Connor, James E.; Sass, Craig; Sickafoose, Amanda A.; Worters, Hannah L.

2016-07-01

Considerable effort has gone into improving the performance and reliability of the SAAO's 74-inch telescope. This included replacing the telescope encoders, refining the pointing model and increasing the telescope throughput. The latter involved re-aluminising the primary and formulating a procedure to ensure optimal alignment of the telescope mirrors. To this end, we developed the necessary hardware and techniques to ensure that such alignment is achieved and maintained, particularly following re-aluminising of the mirrors. In essence, the procedure involves: placing a Taylor Hobson Alignment Telescope on the mechanical rotation axis of the 74-inch (which we define to be the optical axis, since the Cassegrain instruments attach to the associated turntable), then adjusting the tip/tilt of the secondary mirror to get it onto that axis and, lastly, adjusting the tip/tilt of the primary mirror to eliminate coma. An eyepiece (or wavefront camera) is installed at the Cassegrain port for this final step since comatic star images indicate the need to tip/tilt the primary mirror to align it to the secondary. Tuning out any brightness gradients seen in an out-of-focus image of a bright star may also be used for feedback when adjusting the tip/tilt of the primary mirror to null coma.

Production of exotic beams at the LBL 88-Inch Cyclotron by the ISOL method

International Nuclear Information System (INIS)

1990-04-01

The Users of the LBL 88-Inch Cyclotron are preparing a proposal to produce exotic, i.e., radioactive beams. The facility will consist of a high-current 30 MeV cyclotron to generate the radioactive nuclei, an ECR source that can be coupled to different production targets, and the 88-Inch Cyclotron to accelerate the radioactive ions. Thus, the basic concept is that of the double cyclotron system pioneered at Louvain-la-Neuve, although the initial emphasis will be on producing a variety of light proton-rich beams at energies up to 10 MeV/A. At this workshop we wish to outline what is being planned, to invite comments and suggestions, and, especially, to encourage participation. We believe that this facility will be an important step toward establishing the scientific and technical basis for a National High Intensity Facility. This can be achieved through active participation by members of the radioactive beam (RB) community in (1) experiments with high quality radioactive beams of moderate intensity and, (2) R ampersand D on high beam-power targets and highly efficient ion sources. 5 refs., 4 figs

50 CFR Figure 12 to Part 223 - Escape Opening & Cover Dimensions for 71-inch TED

Science.gov (United States)

2010-10-01

... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Escape Opening & Cover Dimensions for 71-inch TED 12 Figure 12 to Part 223 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS THREATENED MARINE AND ANADROMOUS SPECIES Pt. 223, Fig. 12 Figure 12 to...

Peptide Probes Reveal a Hydrophobic Steric Ratchet in the Anthrax Toxin Protective Antigen Translocase.

Science.gov (United States)

Colby, Jennifer M; Krantz, Bryan A

2015-11-06

Anthrax toxin is a tripartite virulence factor produced by Bacillus anthracis during infection. Under acidic endosomal pH conditions, the toxin's protective antigen (PA) component forms a transmembrane channel in host cells. The PA channel then translocates its two enzyme components, lethal factor and edema factor, into the host cytosol under the proton motive force. Protein translocation under a proton motive force is catalyzed by a series of nonspecific polypeptide binding sites, called clamps. A 10-residue guest/host peptide model system, KKKKKXXSXX, was used to functionally probe polypeptide-clamp interactions within wild-type PA channels. The guest residues were Thr, Ala, Leu, Phe, Tyr, and Trp. In steady-state translocation experiments, the channel blocked most tightly with peptides that had increasing amounts of nonpolar surface area. Cooperative peptide binding was observed in the Trp-containing peptide sequence but not the other tested sequences. Trp substitutions into a flexible, uncharged linker between the lethal factor amino-terminal domain and diphtheria toxin A chain expedited translocation. Therefore, peptide-clamp sites in translocase channels can sense large steric features (like tryptophan) in peptides, and while these steric interactions may make a peptide translocate poorly, in the context of folded domains, they can make the protein translocate more rapidly presumably via a hydrophobic steric ratchet mechanism. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Development of a 10-inch HPD with integrated readout electronics

CERN Document Server

Braem, André; Joram, C; Séguinot, Jacques; Weilhammer, Peter; Giunta, M; Malakhov, N; Menzione, A; Pegna, R; Piccioli, A; Raffaelli, F; Sartori, G

2003-01-01

A round 10-in. diameter Hybrid Photodiode (HPD) with spherical entrance window is under development for Cherenkov imaging applications in cosmic ray astronomy. The HPD adopts the fountain focusing electron optics, which, as already demonstrated in the 5 inch Pad HPD, allows for a linear demagnification of the image over practically the full tube diameter. Self-triggering front-end electronics providing also sparse readout capability, has been tested. High-efficiency Rb//2Te cathodes have been produced on a UV extended borosilicate glass windows with very thin conductive underlayers of Indium Tin Oxide. We report on the design of the 10- in. HPD, the fabrication procedure and first tests of a 5-in. HPD with Rb//2Te photocathode and 2048 channels.

Remote target removal for the Oak Ridge 86-inch Cyclotron

International Nuclear Information System (INIS)

Walls, A.A.

1982-01-01

A remotely operated target remover has been plaed in operation at the 86-Inch Cyclotron located in Oak Ridge. The system provides for the remote removal of a target from inside the cyclotron, loading it into a cask, and the removal of the cask from the 1.5 m (5-ft) shielding walls. The remote system consists of multiple electrical and pneumatically operated equipment which is designed for controlled step-by-step operation, operated with an electrical control panel, and monitored by a television system. The target remover has reduced the radiation exposures to operating personnel at the facility and has increased the effective operating time. The system is fast, requires a minimum of skill to operate, and has demonstrated both reliability and durability

Identifying Method of Drunk Driving Based on Driving Behavior

Directory of Open Access Journals (Sweden)

Xiaohua Zhao

2011-05-01

Full Text Available Drunk driving is one of the leading causes contributing to traffic crashes. There are numerous issues that need to be resolved with the current method of identifying drunk driving. Driving behavior, with the characteristic of real-time, was extensively researched to identify impaired driving behaviors. In this paper, the drives with BACs above 0.05% were defined as drunk driving state. A detailed comparison was made between normal driving and drunk driving. The experiment in driving simulator was designed to collect the driving performance data of the groups. According to the characteristics analysis for the effect of alcohol on driving performance, seven significant indicators were extracted and the drunk driving was identified by the Fisher Discriminant Method. The discriminant function demonstrated a high accuracy of classification. The optimal critical score to differentiate normal from drinking state was found to be 0. The evaluation result verifies the accuracy of classification method.

Determination on Damage Mechanism of the Planet Gear of Heavy Vehicle Final Drive

Science.gov (United States)

Ramdan, RD; Setiawan, R.; Sasmita, F.; Suratman, R.; Taufiqulloh

2018-02-01

The works focus on the investigation of damage mechanism of fractured in the form of spalling of the planet gears from the final drive assembly of 160-ton heavy vehicles. The objective of this work is to clearly understand the mechanism of damage. The work is the first stage of the on-going research on the remaining life estimation of such gears. The understanding of the damage mechanism is critical in order to provide accurate estimate of the gear’s remaining life with observed initial damage. The analysis was performed based on the metallurgy laboratory works, including visual observation, macro-micro fractography by optical stereo and optical microscope and micro-vickers hardness test. From visual observation it was observed pitting that form lining defect at common position, which is at gear flank position. From spalling sample it was observed ratchet mark at the boundary between macro pitting and the edge of fractured parts. Further observation on the cross-section of the samples by optical microscope confirm that initial micro pitting occur without spalling of the case hardened surface. Spalling occur when pitting achieve certain critical size, and occur at multiple initiation site of crack propagation. From the present research it was concluded that pitting was resulted due to repeated contact fatigue. In addition, development of micro to macro pitting as well as spalling occur at certain direction towards the top of the gear teeth.

First thin AC-coupled silicon strip sensors on 8-inch wafers

Energy Technology Data Exchange (ETDEWEB)

Bergauer, T., E-mail: thomas.bergauer@oeaw.ac.at [Institute of High Energy Physics of the Austrian Academy of Sciences, Nikolsdorfer Gasse 18, 1050 Wien (Vienna) (Austria); Dragicevic, M.; König, A. [Institute of High Energy Physics of the Austrian Academy of Sciences, Nikolsdorfer Gasse 18, 1050 Wien (Vienna) (Austria); Hacker, J.; Bartl, U. [Infineon Technologies Austria AG, Siemensstrasse 2, 9500 Villach (Austria)

2016-09-11

The Institute of High Energy Physics (HEPHY) in Vienna and the semiconductor manufacturer Infineon Technologies Austria AG developed a production process for planar AC-coupled silicon strip sensors manufactured on 200 μm thick 8-inch p-type wafers. In late 2015, the first wafers were delivered featuring the world's largest AC-coupled silicon strip sensors. Detailed electrical measurements were carried out at HEPHY, where single strip and global parameters were measured. Mechanical studies were conducted and the long-term behavior was investigated using a climate chamber. Furthermore, the electrical properties of various test structures were investigated to validate the quality of the manufacturing process.

Elemental Water Impact Test: Phase 2 36-Inch Aluminum Tank Head

Science.gov (United States)

Vassilakos, Gregory J.

2014-01-01

Spacecraft are being designed based on LS-DYNA simulations of water landing impacts. The Elemental Water Impact Test (EWIT) series was undertaken to assess the accuracy of LS-DYNA water impact simulations. EWIT Phase 2 featured a 36-inch aluminum tank head. The tank head was outfitted with one accelerometer, twelve pressure transducers, three string potentiometers, and four strain gages. The tank head was dropped from heights of 1 foot and 2 feet. The focus of this report is the correlation of analytical models against test data. As a measure of prediction accuracy, peak responses from the baseline LS-DYNA model were compared to peak responses from the tests.

Study of interaction of fatigue damage and ratcheting. Effect of a tensile primary load on torsion fatigue resistance of stainless steel 304 L at ambient temperature

International Nuclear Information System (INIS)

Hakem, N.S.

1987-01-01

Effect of ratcheting on fatigue resistance of a stainless steel 304 L, used for reactor vessels, is studied experimentally. Lifetime of samples is reduced if a static constant tensile load (primary loading) is superimposed to cyclic torsion deformations (secondary loading). An equivalent deformation concept is developed to express a criterion of fatigue rupture under primary loading. No effect is noted on the curve of cyclic strain hardening. This fatigue analysis gives no information on cumulated axial deformation. Progressive elongation, observed during testing, is dependent of primary and secondary loading. Rupture is produced by fatigue because cumulated axial deformation is limited ( 4 cycles at rupture cumulated deformation is [fr

Self-rated driving and driving safety in older adults.

Science.gov (United States)

Ross, Lesley A; Dodson, Joan E; Edwards, Jerri D; Ackerman, Michelle L; Ball, Karlene

2012-09-01

Many U.S. states rely on older adults to self-regulate their driving and determine when driving is no longer a safe option. However, the relationship of older adults' self-rated driving in terms of actual driving competency outcomes is unclear. The current study investigates self-rated driving in terms of (1) systematic differences between older adults with high (good/excellent) versus low (poor/fair/average) self-ratings, and (2) the predictive nature of self-rated driving to adverse driving outcomes in older adults (n=350; mean age 73.9, SD=5.25, range 65-91). Adverse driving outcomes included self-reported incidences of (1) being pulled over by the police, (2) receiving a citation, (3) receiving a recommendation to cease or limit driving, (4) crashes, and (5) state-reported crashes. Results found that older drivers with low self-ratings reported more medical conditions, less driving frequency, and had been given more suggestions to stop/limit their driving; there were no other significant differences between low and high self-raters. Logistic regression revealed older drivers were more likely to have a state-reported crash and receive a suggestion to stop or limit driving. Men were more likely to report all adverse driving outcomes except for receiving a suggestion to stop or limit driving. Regarding self-rated driving, older adults with high ratings were 66% less likely (OR=0.34, 95% CI=0.14-0.85) to have received suggestions to limit or stop driving after accounting for demographics, health and driving frequency. Self-ratings were not predictive of other driving outcomes (being pulled over by the police, receiving a citation, self-reported crashes, or state-reported crashes, ps>0.05). Most older drivers (85.14%) rated themselves as either good or excellent drivers regardless of their actual previous citation or crash rates. Self-rated driving is likely not related to actual driving proficiency as indicated by previous crash involvement in older adults

The Drive-Wise Project: Driving Simulator Training increases real driving performance in healthy older drivers

Directory of Open Access Journals (Sweden)

Gianclaudio eCasutt

2014-05-01

Full Text Available Background: Age-related cognitive decline is often associated with unsafe driving behavior. We hypothesized that 10 active training sessions in a driving simulator increase cognitive and on-road driving performance. In addition, driving simulator training should outperform cognitive training.Methods: Ninety-one healthy active drivers (62 – 87 years were randomly assigned to either (1 a driving simulator training group, (2 an attention training group (vigilance and selective attention, or (3 a control group. The main outcome variables were on-road driving and cognitive performance. Seventy-seven participants (85% completed the training and were included in the analyses. Training gains were analyzed using a multiple regression analysis with planned comparisons.Results: The driving simulator training group showed an improvement in on-road driving performance compared to the attention training group. In addition, both training groups increased cognitive performance compared to the control group. Conclusion: Driving simulator training offers the potential to enhance driving skills in older drivers. Compared to the attention training, the simulator training seems to be a more powerful program for increasing older drivers’ safety on the road.

Investigation of the ductile fracture properties of Type 304 stainless steel plate, welds, and 4-inch pipe

International Nuclear Information System (INIS)

Vassilaros, M.G.; Hays, R.A.; Gudas, J.P.

1985-01-01

J-integral fracture toughness tests were performed on welded 304 stainless steel 2-inch plate and 4-inch diameter pipe. The 2-inch plate was welded using a hot-wire automatic gas tungsten arc process. The tests were performed at 550 0 F, 300 0 F and room temperature. The results of the J-integral tests indicate that the Jsub(Ic) of the base plate ranged from 4400 to 6100 in lbs/in 2 at 550 0 F. The Jsub(Ic) values for the tests performed at 300 0 F and room temperature were beyond the measurement capacity of the specimens and appear to indicate that Jsub(Ic) was greater than 8000 in lb/in 2 . The J-integral tests performed on the weld metal specimens indicate that the Jsub(Ic) values ranged from 930 to 2150 in lbs/in 2 at 550 0 F. The Jsub(Ic) values of the weld metal specimens tested at 300 0 F and room temperature were 2300 and 3000 in lbs/in 2 respectively. One HAZ specimen was tested at 550 0 F and found to have a Jsub(Ic) value of 2980 in lbs/in 2 which indicates that the HAZ is an average of the base metal and weld metal toughness. These test results indicate that there is a significant reduction in the initiation fracture toughness as a result of welding. The second phase of this task dealt with the fracture toughness testing of 4-inch diameter 304 stainless steel pipes containing a gas tungsten arc weld. The pipes were tested at 550 0 F in four point bending. Three tests were performed, two with a through wall flaw growing circumferentially and the third pipe had a part through radial flaw in combination with the circumferential flaw. These tests were performed using unloading compliance and d.c. potential drop crack length estimate methods. The results of these tests indicate that the presence of a complex crack (radial and circumferential) reduces in the initiation toughness and the tearing modulus of the pipe material compared to a pipe with only a circumferentially growing crack. (orig.)

Electrical drives for direct drive renewable energy systems

CERN Document Server

Mueller, Markus

2013-01-01

Wind turbine gearboxes present major reliability issues, leading to great interest in the current development of gearless direct-drive wind energy systems. Offering high reliability, high efficiency and low maintenance, developments in these direct-drive systems point the way to the next generation of wind power, and Electrical drives for direct drive renewable energy systems is an authoritative guide to their design, development and operation. Part one outlines electrical drive technology, beginning with an overview of electrical generators for direct drive systems. Principles of electrical design for permanent magnet generators are discussed, followed by electrical, thermal and structural generator design and systems integration. A review of power electronic converter technology and power electronic converter systems for direct drive renewable energy applications is then conducted. Part two then focuses on wind and marine applications, beginning with a commercial overview of wind turbine drive systems and a...

Self-rated Driving and Driving Safety in Older Adults

OpenAIRE

Ross, Lesley A.; Dodson, Joan; Edwards, Jerri D.; Ackerman, Michelle L.; Ball, Karlene

2012-01-01

Many U.S. states rely on older adults to self-regulate their driving and determine when driving is no longer a safe option. However, the relationship of older adults’ self-rated driving in terms of actual driving competency outcomes is unclear. The current study investigates self-rated driving in terms of (1) systematic differences between older adults with high (good/excellent) versus low (poor/fair/average) self-ratings, and (2) the predictive nature of self-rated driving to adverse driving...

Full scale ambient water flow tests of a 10-inch emergency release coupling for LNG transfer

NARCIS (Netherlands)

Putte, L.J. van der; Webber, T.; Bokhorst, E. van; Revell, C.

2016-01-01

For LNG transfer in ship-to-ship and ship-to-shore configurations emergency release couplings (F.RC) in combination with loading arms and multi-composite hoses are applied In view of a demand for increasing transfer flow rates in offshore LNG applications a 10-inch ERC has been developed intended

Environmental concerns drive project planning and design

International Nuclear Information System (INIS)

Hamilton, G.M.

1994-01-01

This paper describes the measures used to retrofit and requalify a Northwest Pipeline Corp., pipeline near Seattle, Washington. The pipeline is a 26 inch transmission line which has lost operating pressure because of the growth in Seattle's population. The pipeline was redesigned to requalify to a maximum pressure of 809 pounds per square inch. The paper describes the environmental issues faced during the construction and reconstruction efforts to protect wetlands and dispose of pipeline wastes. It describes the methods for cleaning the inside of the pipelines using various chemicals and cleaning tools

NO PLIF Imaging in the CUBRC 48 Inch Shock Tunnel

Science.gov (United States)

Jiang, N.; Bruzzese, J.; Patton, R.; Sutton J.; Lempert W.; Miller, J. D.; Meyer, T. R.; Parker, R.; Wadham, T.; Holden, M.;

ECR heavy-ion source for the LBL 88-inch cyclotron

International Nuclear Information System (INIS)

Clark, D.J.; Kalnins, J.G.; Lyneis, C.M.

1983-03-01

An Electron Cyclotron Resonance (ECR) heavy-ion source is under construction at the LBL 88-Inch Cyclotron. This source will produce very-high-charge-state heavy ions, such as 0 8 + and Ar 12 + , which will increase cyclotron energies by a factor of 2-4, up to A = 80. It is a two-stage source using room-temperature coils, a permanent-magnet sextupole, and a 6-9 GHz microwave system. Design features include adjustable first-to-second-stage plasma coupling, a variable second-stage mirror ratio, high-conductance radial pumping of the second stage, and a beam-diagnostic system. A remotely movable extraction electrode will optimize extraction efficiency. The project includes construction of a transport line and improvements to the cyclotron axial-injection system. The construction period is expected to be two years

Dementia & Driving

Science.gov (United States)

... have to give up driving. Many people associate driving with self-reliance and freedom; the loss of driving privileges ... familiar roads and avoid long distances. Avoid heavy traffic and heavily traveled roads. Avoid driving at night and in bad weather. Reduce the ...

A qualitative exploration of driving stress and driving discourtesy.

Science.gov (United States)

Scott-Parker, B; Jones, C M; Rune, K; Tucker, J

2018-05-31

Driving courtesy, and conversely driving discourtesy, recently has been of great interest in the public domain. In addition, there has been increasing recognition of the negative impact of stress upon the individual's health and wellbeing, with a plethora of interventions aimed at minimising stress more generally. The research literature regarding driving dis/courtesy, in comparison, is scant, with a handful of studies examining the dis/courteous driving behaviour of road users, and the relationship between driving discourtesy and driving stress. To examine courteous and discourteous driving experiences, and to explore the impact of stress associated with such driving experiences. Thirty-eight drivers (20 females) from the Sunshine Coast region volunteered to participate in one of four 1-1.5 h focus groups. Content analysis used the verbatim utterances captured via an Mp3 device. Three themes pertaining to stressful and discourteous interactions were identified. Theme one pertained to the driving context: road infrastructure (eg, roundabouts, roadwork), vehicles (eg, features), location (eg, country vs city, unfamiliar areas), and temporal aspects (eg, holidays). Theme two pertained to other road users: their behaviour (eg, tailgating, merging), and unknown factors (eg, illicit and licit drug use). Theme three pertained to the self as road user: their own behaviours (eg, deliberate intimidation), and their emotions (eg, angry reaction to other drivers, being in control). Driving dis/courtesy and driving stress is a complex phenomenon, suggesting complex intervention efforts are required. Driving discourtesy was reported as being highly stressful, therefore intervention efforts which encourage driving courtesy and which foster emotional capacity to cope with stressful circumstances appear warranted. Copyright © 2018. Published by Elsevier Ltd.

Project Waiver of American Iron and Steel Requirements to the Napa Sanitation District for 24-Inch Diameter Butterfly Valves

Science.gov (United States)

Waiver approval by EPA pursuant to the American Iron and Steel Requirements of the Clean Water Act Section 608 to the Napa Sanitation District in California for the purchase of 24-inch butterfly valves.

Seismic fragility test of a 6-inch diameter pipe system

International Nuclear Information System (INIS)

Chen, W.P.; Onesto, A.T.; DeVita, V.

1987-02-01

This report contains the test results and assessments of seismic fragility tests performed on a 6-inch diameter piping system. The test was funded by the US Nuclear Regulatory Commission (NRC) and conducted by ETEC. The objective of the test was to investigate the ability of a representative nuclear piping system to withstand high level dynamic seismic and other loadings. Levels of loadings achieved during seismic testing were 20 to 30 times larger than normal elastic design evaluations to ASME Level D limits would permit. Based on failure data obtained during seismic and other dynamic testing, it was concluded that nuclear piping systems are inherently able to withstand much larger dynamic seismic loadings than permitted by current design practice criteria or predicted by the probabilistic risk assessment (PRA) methods and several proposed nonlinear methods of failure analysis

Study on water leak-tightness of small leaks on a 1 inch cylinder valve

International Nuclear Information System (INIS)

Miyazawa, T.; Kasai, Y.; Inabe, N.; Aritomi, M.

2002-01-01

Practical thresholds for water leak-tightness of small leaks were determined by experimentation. Measurements for small leak samples were taken of air leakage rates and water leakage rates for identical leak samples in order to identify parameters that influence water leak-tightness threshold. Four types of leaks were evaluated: a fine wire inserted in an O-ring seal, a glass capillary tube, a stainless steel orifice, and a scratched valve stem on a 1 inch UF 6 cylinder valve. Experimental results demonstrated that the key parameter for water leak-tightness is the opening size of the leak hole. The maximum allowable hole size to achieve water leak-tightness ranged from 10 to 20 μm in diameter in this study. Experimental results with 1 inch UF 6 cylinder valve samples demonstrated that the acceptance criteria for preshipment leakage test, 1x10 -3 ref-cm 3 .s -1 , as prescribed in ANSI N14.5 is an appropriate value from the point of view of water leak-tightness for enriched UF 6 packages. The mechanism of water leak-tightness is plugging by tiny particles existing in water. The water used in experiments in this study contained far fewer particles than in water assumed to be encountered under accident conditions of transport. Therefore, the water leak-tightness threshold determined in this study is a conservative value in a practical evaluation. (author)

The dimensional changes of a 24 inch diameter vessel during a campaign of successive glass making runs

International Nuclear Information System (INIS)

Chidley, B.E.

1983-01-01

Throughout the life of a 24 inch diameter Glass Making Vessel used on the inactive Harvest Vitrification Plant dimensional measurements have been recorded. When glass is present the diameter increases due to thermal stresses. Some permanent longitudinal extension (about 1%) occurred over the 20 runs comprising the glass-making campaign. (author)

Electric drives

CERN Document Server

Boldea, Ion

2005-01-01

ENERGY CONVERSION IN ELECTRIC DRIVESElectric Drives: A DefinitionApplication Range of Electric DrivesEnergy Savings Pay Off RapidlyGlobal Energy Savings Through PEC DrivesMotor/Mechanical Load MatchMotion/Time Profile MatchLoad Dynamics and StabilityMultiquadrant OperationPerformance IndexesProblemsELECTRIC MOTORS FOR DRIVESElectric Drives: A Typical ConfigurationElectric Motors for DrivesDC Brush MotorsConventional AC MotorsPower Electronic Converter Dependent MotorsEnergy Conversion in Electric Motors/GeneratorsPOWER ELECTRONIC CONVERTERS (PECs) FOR DRIVESPower Electronic Switches (PESs)The

29 CFR 1910.219 - Mechanical power-transmission apparatus.

Science.gov (United States)

2010-07-01

... dimensions specified in this paragraph shall apply to all guards, except horizontal overhead belts, rope... drives of twenty (20) inch centers or under shall be not less than one-fourth inch from the nearest... one-fourth (11/4) inches inside diameter, or larger. If made of metal shapes or bars, their section...

Older drivers with cognitive impairment: Perceived changes in driving skills, driving-related discomfort and self-regulation of driving

DEFF Research Database (Denmark)

Meng, A.; Siren, A.; Teasdale, Thomas William

2013-01-01

The results of a previous study indicate that in general, older drivers who recognise cognitive problems show realistic self-assessment of changes in their driving skills and that driving-related discomfort may function as an indirect monitoring of driving ability, contributing to their safe...... drivers may recognise cognitive problems, they tend not to recognise changes to their driving, which may reflect reluctance to acknowledge the impact of cognitive impairment on their driving. Furthermore, the results suggest that driving-related discomfort plays an important role in the self......-regulation of driving among cognitively impaired older drivers. However, it is less clear what triggers driving-related discomfort among cognitively impaired older drivers indicating that it may be a less reliable aspect of their self-monitoring of driving ability....

Drive Stands

Data.gov (United States)

Federal Laboratory Consortium — The Electrical Systems Laboratory (ESL)houses numerous electrically driven drive stands. A drive stand consists of an electric motor driving a gearbox and a mounting...

Comparing Expert and Novice Driving Behavior in a Driving Simulator

Directory of Open Access Journals (Sweden)

Hiran B. Ekanayake

2014-02-01

Full Text Available This paper presents a study focused on comparing driving behavior of expert and novice drivers in a mid-range driving simulator with the intention of evaluating the validity of driving simulators for driver training. For the investigation, measurements of performance, psychophysiological measurements, and self-reported user experience under different conditions of driving tracks and driving sessions were analyzed. We calculated correlations between quantitative and qualitative measures to enhance the reliability of the findings. The experiment was conducted involving 14 experienced drivers and 17 novice drivers. The results indicate that driving behaviors of expert and novice drivers differ from each other in several ways but it heavily depends on the characteristics of the task. Moreover, our belief is that the analytical framework proposed in this paper can be used as a tool for selecting appropriate driving tasks as well as for evaluating driving performance in driving simulators.

Cognitive problems, self-rated changes in driving skills, driving-related discomfort and self-regulation of driving in old drivers

DEFF Research Database (Denmark)

Meng, Annette; Siren, Anu Kristiina

2012-01-01

Ageing in general is associated with functional decline that may have an adverse effect on driving. Nevertheless, older drivers have been found to show good judgement and to self-regulate their driving, which may enable them to continue driving safely despite functional decline. The process...... of the self-monitoring of driving ability and the awareness of functional decline, and its association with the self-regulation of driving is, however, not fully understood. The aim of the present study was to examine the perceived changes in driving skills, the discomfort experienced in driving, and the self......-related discomfort is an important factor affecting the self-regulation of driving. Finally, the findings indicate that driving-related discomfort functions as an indirect self-monitoring of driving ability and may contribute to the safe driving performance of Danish older drivers....

Design rules of mechanical structure of reactors. Damage due to cyclic loading. Progressive distortion. Practical analysis of ratcheting

International Nuclear Information System (INIS)

Clement, Gerard; Cousseran, Pierre; Lebey, Jacques; Moulin, Didier; Roche, Roland; Tremblais, Andre.

1982-08-01

At first is given a definition of what is ratcheting. A short discussion shows that computation results do not agree with experimental results. This is attributed to the complexity of the real material behavior. These considerations lead to try to build a design rule mainly based on the results of experimental tests. A large experimental program is in progress at CEN-Saclay. Using these results and the results available in open litterature, it was possible to propose a rule based on the concept of effective primary stress Psub(eff). The effective primary stress is a fictitious primary stress giving the same effects that the real loading (it is to say the same effect that the combination of an applied primary stress P and a cyclic straining). Determination of an upper bound value of Psub(eff) is made with the help of an efficiency diagram. More precisely the efficiency diagram include a curve giving a conservative value of an efficiency index V=P/Psub(eff) as a function of the secondary quotient SQ=ΔQ/P. Finally limitation of Psub(eff) intensity is discussed in regard with the current practice [fr

DrivingSense: Dangerous Driving Behavior Identification Based on Smartphone Autocalibration

Directory of Open Access Journals (Sweden)

Chunmei Ma

2017-01-01

Full Text Available Since pervasive smartphones own advanced computing capability and are equipped with various sensors, they have been used for dangerous driving behaviors detection, such as drunk driving. However, sensory data gathered by smartphones are noisy, which results in inaccurate driving behaviors estimations. Some existing works try to filter noise from sensor readings, but usually only the outlier data are filtered. The noises caused by hardware of the smartphone cannot be removed from the sensor reading. In this paper, we propose DrivingSense, a reliable dangerous driving behavior identification scheme based on smartphone autocalibration. We first theoretically analyze the impact of the sensor error on the vehicle driving behavior estimation. Then, we propose a smartphone autocalibration algorithm based on sensor noise distribution determination when a vehicle is being driven. DrivingSense leverages the corrected sensor parameters to identify three kinds of dangerous behaviors: speeding, irregular driving direction change, and abnormal speed control. We evaluate the effectiveness of our scheme under realistic environments. The results show that DrivingSense, on average, is able to detect the driving direction change event and abnormal speed control event with 93.95% precision and 90.54% recall, respectively. In addition, the speed estimation error is less than 2.1 m/s, which is an acceptable range.

Driving Style Analysis Using Primitive Driving Patterns With Bayesian Nonparametric Approaches

OpenAIRE

Wang, Wenshuo; Xi, Junqiang; Zhao, Ding

2017-01-01

Analysis and recognition of driving styles are profoundly important to intelligent transportation and vehicle calibration. This paper presents a novel driving style analysis framework using the primitive driving patterns learned from naturalistic driving data. In order to achieve this, first, a Bayesian nonparametric learning method based on a hidden semi-Markov model (HSMM) is introduced to extract primitive driving patterns from time series driving data without prior knowledge of the number...

IMPACT TESTING OF MATERIALS USING AN EIGHT-INCH AIR GUN AND COMPUTER REDUCTION OF DATA

Energy Technology Data Exchange (ETDEWEB)

Thorne, L. F.

1973-10-01

A mechanical shock actuator has been converted into an air gun capable of firing 8-inch-·diameter (20.32 cm) projectiles to velocities exceeding 1000 fps (304.8 m/ s). This new capability has been used to study the effect of impact velocity upon the energy.absorbed by crushable materials. Shockpulse data is reduced by computer techniques and test results are displayed in either tabular or graphic format by use of the C DC 6600 Calcomp plotter.

Control rod drive

International Nuclear Information System (INIS)

Okutani, Tetsuro.

1988-01-01

Purpose: To provide a simple and economical control rod drive using a control circuit requiring no pulse circuit. Constitution: Control rods in a BWR type reactor are driven by hydraulic pressure and inserted or withdrawn in the direction of applying the hydraulic pressure. The direction of the hydraulic pressure is controlled by a direction control valve. Since the driving for the control rod is extremely important in view of the operation, a self diagnosis function is disposed for rapid inspection of possible abnormality. In the present invention, two driving contacts are disposed each by one between the both ends of a solenoid valve of the direction control valve for driving the control rod and the driving power source, and diagnosis is conducted by alternately operating them. Therefore, since it is only necessary that the control circuit issues a driving instruction only to one of the two driving contacts, the pulse circuit is no more required. Further, since the control rod driving is conducted upon alignment of the two driving instructions, the reliability of the control rod drive can be improved. (Horiuchi, T.)

Dimensions of driving anger and their relationships with aberrant driving.

Science.gov (United States)

Zhang, Tingru; Chan, Alan H S; Zhang, Wei

2015-08-01

The purpose of this study was to investigate the relationship between driving anger and aberrant driving behaviours. An internet-based questionnaire survey was administered to a sample of Chinese drivers, with driving anger measured by a 14-item short Driving Anger Scale (DAS) and the aberrant driving behaviours measured by a 23-item Driver Behaviour Questionnaire (DBQ). The results of Confirmatory Factor Analysis demonstrated that the three-factor model (hostile gesture, arrival-blocking and safety-blocking) of the DAS fitted the driving anger data well. The Exploratory Factor Analysis on DBQ data differentiated four types of aberrant driving, viz. emotional violation, error, deliberate violation and maintaining progress violation. For the anger-aberration relation, it was found that only "arrival-blocking" anger was a significant positive predictor for all four types of aberrant driving behaviours. The "safety-blocking" anger revealed a negative impact on deliberate violations, a finding different from previously established positive anger-aberration relation. These results suggest that drivers with different patterns of driving anger would show different behavioural tendencies and as a result intervention strategies may be differentially effective for drivers of different profiles. Copyright © 2015 Elsevier Ltd. All rights reserved.

Leak in spiral weld in a 16 inches gas pipeline

Energy Technology Data Exchange (ETDEWEB)

Fazzini, Pablo G; Bona, Jeremias de [GIE S.A., Mar del Plata (Argentina); Otegui, Jose L [University of Mar del Plata (Argentina)

2009-07-01

This paper discusses a failure analysis after a leak in the spiral weld of a 16 inches natural gas pipeline, in service since 1974. The leak was the result of the coalescence of two different defects, on each surface of the pipe wall, located in the center of the inner cord of the helical DSAW weld. Fractographic and metallographic studies revealed that the leak was a combination of three conditions. During fabrication of the pipe, segregation in grain boundary grouped in mid weld. During service, these segregations underwent a process of selective galvanic corrosion. One of these volumetric defects coincided with a tubular pore in the outer weld. Pigging of the pipeline in 2005 for cleaning likely contributed to the increase of the leak flow, when eliminating corrosion product plugs. Although these defects are likely to repeat, fracture mechanics shows that a defect of this type is unlikely to cause a blowout. (author)

Radiation effects testing at the 88-Inch Cyclotron at LBNL

International Nuclear Information System (INIS)

McMahan, Margaret A.; Koga, Rokotura

2002-01-01

The effects of ionizing particles on sensitive microelectronics is an important component of the design of systems as diverse as satellites and space probes, detectors for high energy physics experiments and even internet server farms. Understanding the effects of radiation on human cells is an equally important endeavor directed towards future manned missions in space and towards cancer therapy. At the 88-Inch Cyclotron at the Berkeley Laboratory, facilities are available for radiation effects testing (RET) with heavy ions and with protons. The techniques for doing these measurements and the advantages of using a cyclotron will be discussed, and the Cyclotron facilities will be compared with other facilities worldwide. RET of the same part at several facilities of varying beam energy can provide tests of the simple models used in this field and elucidate the relative importance of atomic and nuclear effects. The results and implications of such measurements will be discussed

Risk assessment of K basin twelve-inch drain valve failure from a postulated seismic initiating event

International Nuclear Information System (INIS)

MORGAN, R.G.

1999-01-01

The Spent Nuclear Fuel (SNF) Project will transfer metallic SNF from the Hanford 105 K-East and 105 K-West Basins to safe interim storage in the Canister Storage Building in the 200 Area. The initial basis for design, fabrication, installation, and operation of the fuel removal systems was that the basin leak rates which could result from a postulated accident condition would not be excessive relative to reasonable recovery operations. However, an additional potential K Basin water leak path is through the K Basin drain valves. Three twelve-inch drain valves are located in the main basin bays along the north wall. The sumps containing the valves are filled with concrete which covers the drain valve body. Visual observations suggest that only the valve's bonnet and stem are exposed above the basin concrete floor. It was recognized, however, that damage of the drain valve bonnet or stem during a seismic initiating event could provide a potential K Basin water leak path. The objectives of this activity are to: (1) evaluate the risk of damaging the three twelve-inch drain valves located along the north wall of the main basin from a seismic initiating event, and (2) determine the associated potential leak rate from a damaged valve

Risk assessment of K basin twelve-inch drain valve failure from a postulated seismic initiating event

Energy Technology Data Exchange (ETDEWEB)

MORGAN, R.G.

1999-04-06

The Spent Nuclear Fuel (SNF) Project will transfer metallic SNF from the Hanford 105 K-East and 105 K-West Basins to safe interim storage in the Canister Storage Building in the 200 Area. The initial basis for design, fabrication, installation, and operation of the fuel removal systems was that the basin leak rates which could result from a postulated accident condition would not be excessive relative to reasonable recovery operations. However, an additional potential K Basin water leak path is through the K Basin drain valves. Three twelve-inch drain valves are located in the main basin bays along the north wall. The sumps containing the valves are filled with concrete which covers the drain valve body. Visual observations suggest that only the valve's bonnet and stem are exposed above the basin concrete floor. It was recognized, however, that damage of the drain valve bonnet or stem during a seismic initiating event could provide a potential K Basin water leak path. The objectives of this activity are to: (1) evaluate the risk of damaging the three twelve-inch drain valves located along the north wall of the main basin from a seismic initiating event, and (2) determine the associated potential leak rate from a damaged valve.

Older driver fitness-to-drive evaluation using naturalistic driving data.

Science.gov (United States)

Guo, Feng; Fang, Youjia; Antin, Jonathan F

2015-09-01

As our driving population continues to age, it is becoming increasingly important to find a small set of easily administered fitness metrics that can meaningfully and reliably identify at-risk seniors requiring more in-depth evaluation of their driving skills and weaknesses. Sixty driver assessment metrics related to fitness-to-drive were examined for 20 seniors who were followed for a year using the naturalistic driving paradigm. Principal component analysis and negative binomial regression modeling approaches were used to develop parsimonious models relating the most highly predictive of the driver assessment metrics to the safety-related outcomes observed in the naturalistic driving data. This study provides important confirmation using naturalistic driving methods of the relationship between contrast sensitivity and crash-related events. The results of this study provide crucial information on the continuing journey to identify metrics and protocols that could be applied to determine seniors' fitness to drive. Published by Elsevier Ltd.

Automated driving safer and more efficient future driving

CERN Document Server

Horn, Martin

2017-01-01

The main topics of this book include advanced control, cognitive data processing, high performance computing, functional safety, and comprehensive validation. These topics are seen as technological bricks to drive forward automated driving. The current state of the art of automated vehicle research, development and innovation is given. The book also addresses industry-driven roadmaps for major new technology advances as well as collaborative European initiatives supporting the evolvement of automated driving. Various examples highlight the state of development of automated driving as well as the way forward. The book will be of interest to academics and researchers within engineering, graduate students, automotive engineers at OEMs and suppliers, ICT and software engineers, managers, and other decision-makers.

Pile Driving

Science.gov (United States)

1987-01-01

Machine-oriented structural engineering firm TERA, Inc. is engaged in a project to evaluate the reliability of offshore pile driving prediction methods to eventually predict the best pile driving technique for each new offshore oil platform. Phase I Pile driving records of 48 offshore platforms including such information as blow counts, soil composition and pertinent construction details were digitized. In Phase II, pile driving records were statistically compared with current methods of prediction. Result was development of modular software, the CRIPS80 Software Design Analyzer System, that companies can use to evaluate other prediction procedures or other data bases.

Driver headway choice : A comparison between driving simulator and real-road driving

NARCIS (Netherlands)

Risto, M.; Martens, M.H.

2014-01-01

Driving simulators have become an established tool in driver behaviour research by offering a controllable, safe and cost-effective alternative to real world driving. A challenge for using driving simulators as a research tool has been to elicit driving behaviour that equals real world driving. With

Driver headway choice: a comparison between driving simulator and real-road driving

NARCIS (Netherlands)

Risto, Malte; Martens, Marieke Hendrikje

2014-01-01

Driving simulators have become an established tool in driver behaviour research by offering a controllable, safe and cost-effective alternative to real world driving. A challenge for using driving simulators as a research tool has been to elicit driving behaviour that equals real world driving. With

Driving Safety and Fitness to Drive in Sleep Disorders.

Science.gov (United States)

Tippin, Jon; Dyken, Mark Eric

2017-08-01

Driving an automobile while sleepy increases the risk of crash-related injury and death. Neurologists see patients with sleepiness due to obstructive sleep apnea, narcolepsy, and a wide variety of neurologic disorders. When addressing fitness to drive, the physician must weigh patient and societal health risks and regional legal mandates. The Driver Fitness Medical Guidelines published by the National Highway Traffic Safety Administration (NHTSA) and the American Association of Motor Vehicle Administrators (AAMVA) provide assistance to clinicians. Drivers with obstructive sleep apnea may continue to drive if they have no excessive daytime sleepiness and their apnea-hypopnea index is less than 20 per hour. Those with excessive daytime sleepiness or an apnea-hypopnea index of 20 per hour or more may not drive until their condition is effectively treated. Drivers with sleep disorders amenable to pharmaceutical treatment (eg, narcolepsy) may resume driving as long as the therapy has eliminated excessive daytime sleepiness. Following these guidelines, documenting compliance to recommended therapy, and using the Epworth Sleepiness Scale to assess subjective sleepiness can be helpful in determining patients' fitness to drive.

HARMONIC DRIVE SELECTION

Directory of Open Access Journals (Sweden)

Piotr FOLĘGA

2014-03-01

Full Text Available The variety of types and sizes currently in production harmonic drive is a problem in their rational choice. Properly selected harmonic drive must meet certain requirements during operation, and achieve the anticipated service life. The paper discusses the problems associated with the selection of the harmonic drive. It also presents the algorithm correct choice of harmonic drive. The main objective of this study was to develop a computer program that allows the correct choice of harmonic drive by developed algorithm.

Contribution to the validation of thermal ratchetting prevision methods in metallic structures

International Nuclear Information System (INIS)

Rakotovelo, A.M.

1998-03-01

This work concerns the steady state assessment in the metallic structures subjected to thermomechanical cyclic loadings in biaxial stress state. The effect of the short time mechanical overloads is also investigated. The first chapter is devoted to a bibliographic research concerning the behaviour of the materials and the structures in the cyclic plasticity. Some works relate to the experimental aspect as well as the numerical one for the steady state assessment of such structures are presented. The experimental part of the study is presented in the second chapter. The experimental device was carried out in order to prescribe tension and torsion forces combined with cyclic thermal loading. Some tests was then carried out, among these tests certain include some overloads in tension or torsion. The last chapter describes the numerical calculations using different models (linear isotropic hardening, linear kinematic hardening and elasto-viscoplastic Chaboche's model) and the application of some simplified methods for the ratchetting assessment in the structures. We have considered two categories of methods. The first one is based on an elastic analysis (Bree's diagram, 3 Sm rule, efficiency rule) and the second one combines elastic analysis and elastoplastic analysis of the first cycle (Gatt's and Taleb's methods). The results of this study have enabled: to validate in the biaxial stress state an expression which takes into account the effect of mechanical short time overloads; to test the performances of considered models to describe the evolution of the structure during the first cycle and to take into account the effect of short time overloads. Among the considered models, the elastoplastic Chaboche's model seems to be the most accurate to describe the structure's behaviour during the first cycles; to validate some simplified methods. Certain methods based only on elastic analysis (Bee's diagram and efficiency rule) seem not suitable for the considered kind of

Control rod drives

International Nuclear Information System (INIS)

Futatsugi, Masao.

1980-01-01

Purpose: To secure the reactor operation safety by the provision of a fluid pressure detecting section for control rod driving fluid and a control rod interlock at the midway of the flow pass for supplying driving fluid to the control rod drives. Constitution: Between a driving line and a direction control valve are provided a pressure detecting portion, an alarm generating device, and a control rod inhibition interlock. The driving fluid from a driving fluid source is discharged by way of a pump and a manual valve into the reactor in which the control rods and reactor fuels are contained. In addition, when the direction control valve is switched and the control rods are inserted and extracted by the control rod drives, the pressure in the driving line is always detected by the pressure detection section, whereby if abnormal pressure is resulted, the alarm generating device is actuated to warn the abnormality and the control rod inhibition interlock is actuated to lock the direction control valve thereby secure the safety operation of the reactor. (Seki, T.)

Double-lock ratchet mechanism revealing the role of  SER-344 in FoF1 ATP synthase

KAUST Repository

Beke-Somfai, T.

2011-03-07

In a majority of living organisms, FoF1 ATP synthase performs the fundamental process of ATP synthesis. Despite the simple net reaction formula, ADP+Pi→ATP+H2O, the detailed step-by-step mechanism of the reaction yet remains to be resolved owing to the complexity of this multisubunit enzyme. Based on quantum mechanical computations using recent high resolution X-ray structures, we propose that during ATP synthesis the enzyme first prepares the inorganic phosphate for the γP-OADP bond-forming step via a double-proton transfer. At this step, the highly conserved αS344 side chain plays a catalytic role. The reaction thereafter progresses through another transition state (TS) having a planar ion configuration to finally form ATP. These two TSs are concluded crucial for ATP synthesis. Using stepwise scans and several models of the nucleotide-bound active site, some of the most important conformational changes were traced toward direction of synthesis. Interestingly, as the active site geometry progresses toward the ATP-favoring tight binding site, at both of these TSs, a dramatic increase in barrier heights is observed for the reverse direction, i.e., hydrolysis of ATP. This change could indicate a "ratchet" mechanism for the enzyme to ensure efficacy of ATP synthesis by shifting residue conformation and thus locking access to the crucial TSs.

LOFT transient thermal analysis for 10 inch primary coolant blowdown piping weld

International Nuclear Information System (INIS)

Howell, S.K.

1978-01-01

A flaw in a weld in the 10 inch primary coolant blowdown piping was discovered by LOFT personnel. As a result of this, a thermal analysis and fracture mechanics analysis was requested by LOFT personnel. The weld and pipe section were analyzed for a complete thermal cycle, heatup and Loss of Coolant Experiment (LOCE), using COUPLE/MOD2, a two-dimensional finite element heat conduction code. The finite element representation used in this analysis was generated by the Applied Mechanics Branch. The record of nodal temperatures for the entire transient was written on tape VSN=T9N054, and has been forwarded to the Applied Mechanics Branch for use in their mechanical analysis. Specific details and assumptions used in this analysis are found in appropriate sections of this report

Electric motor drive unit, especially adjustment drive for vehicles

Energy Technology Data Exchange (ETDEWEB)

Litterst, P

1980-05-29

An electric motor drive unit, particularly an adjustment drive for vehicles with at least two parallel drive shafts is described, which is compact and saves space, and whose manufacturing costs are low compared with those of well-known drive units of this type. The drive unit contains a suitable number of magnet systems, preferably permanent magnet systems, whose pole axes are spaced and run parallel. The two pole magnet systems have diametrically opposite shell-shaped segments, to which the poles are fixed. In at least one magnet system the two segments are connected by diametrically opposite flat walls parallel to the pole axes to form a single magnetic circuit pole housing. The segments of at least one other magnet system are arranged on this pole housing so that one of these flat walls is a magnetically conducting, connecting component of the magnetic circuit of the other magnet system.

Drivers’ Age, Gender, Driving Experience, and Aggressiveness as Predictors of Aggressive Driving Behaviour

Directory of Open Access Journals (Sweden)

Perepjolkina Viktorija

2011-12-01

Full Text Available Recent years have seen a growing interest in the problem of aggressive driving. In the presentstudy two demographic variables (gender and age, two non-psychological driving-experiencerelated variables (annual mileage and legal driving experience in years and aggressiveness asa personality trait (including behavioural and affective components as psychological variableof individual differences were examined as potential predictors of aggressive driving. The aimof the study was to find out the best predictors of aggressive driving behaviour. The study wasbased on an online survey, and 228 vehicle drivers in Latvia participated in it. The questionnaireincluded eight-item Aggressive Driving Scale (Bone & Mowen, 2006, short Latvian versionof the Buss-Perry Aggression Questionnaire (AQ; Buss & Perry, 1992, and questions gainingdemographic and driving experience information. Gender, age and annual mileage predictedaggressive driving: being male, young and with higher annual driving exposure were associatedwith higher scores on aggressive driving. Dispositional aggressiveness due to anger componentwas a significant predictor of aggressive diving score. Physical aggression and hostility wereunrelated to aggressive driving. Altogether, the predictors explained a total of 28% of thevariance in aggressive driving behaviour. Findings show that dispositional aggressiveness,especially the anger component, as well as male gender, young age and higher annual mileagehas a predictive validity in relation to aggressive driving. There is a need to extend the scope ofpotential dispositional predictors pertinent to driving aggression.

A vibration sieve

Energy Technology Data Exchange (ETDEWEB)

Alekhin, S.A.; Denisenko, V.V.; Dzhalalov, M.G.; Kirichek, F.P.; Pitatel, Yu.A.; Prokopov, L.I.; Tikhonov, Yu.P.

1982-01-01

A vibration sieve is proposed which includes a vibration drive, a body and a screen installed on shock absorbers, a device for washing out the screen, and a subassembly for loading the material. To increase the operational reliability and effectiveness of the vibration sieve by improving the cleaning of the screen, the loading subassembly is equipped with a baffle with a lever which is hinged to it. The device for washing out the screen is made in the form of an electromagnet with a connecting rod, a switch and an eccentric, a friction ratchet mechanism and sprinkling systems. Here, the latter are interconnected, using a connecting rod, while the sprinkling system is installed on rollers under the screen. The electromagnetic switch is installed under the lever. The body is made with grooves for installing the sprinkling system. The vibration sieve is equipped with a switch which interacts with the connecting rod. The friction ratchet mechanism is equipped with a lug.

Educational Biofeedback Driving Simulator as a Drink-Driving Prevention Strategy.

Science.gov (United States)

Howat, Peter; And Others

1991-01-01

Used experimental driving simulator as basis for strategy to encourage a reduction in drunk driving prevalence using adult male subjects (n=36) who participated in a study group and controls (n=36). Results indicated study group subjects significantly decreased their drunk driving compared to the control group. (ABL)

Do aggressive driving and negative emotional driving mediate the link between impulsiveness and risky driving among young Italian drivers?

Science.gov (United States)

Smorti, Martina; Guarnieri, Silvia

2016-01-01

The present study examined the contribution of impulsiveness and aggressive and negative emotional driving to the prediction of traffic violations and accidents taking into account potential mediation effects. Three hundred and four young drivers completed self-report measures assessing impulsiveness, aggressive and negative emotional driving, driving violations, and accidents. Structural equation modeling was used to assess the direct and indirect effects of impulsiveness on violations and accidents among young drivers through aggressive and negative emotional driving. Impulsiveness only indirectly influenced drivers' violations on the road via both the behavioral and emotional states of the driver. On the contrary, impulsiveness was neither directly nor indirectly associated with traffic accidents. Therefore, impulsiveness modulates young drivers' behavioral and emotional states while driving, which in turn influences risky driving.

High spatial resolution gamma imaging detector based on a 5 inch diameter R3292 Hamamatsu PSPMT

International Nuclear Information System (INIS)

Wojcik, R.; Majewski, S.; Kross, B.; Weisenberger, A.G.; Steinbach, D.

1998-01-01

High resolution imaging gamma-ray detectors were developed using Hamamatsu's 5 inch diameter R3292 position sensitive PMT (PSPMT) and a variety of crystal scintillator arrays. Special readout techniques were used to maximize the active imaging area while reducing the number of readout channels. Spatial resolutions approaching 1 mm were obtained in a broad energy range from 20 to 511 keV. Results are also presented of coupling the scintillator arrays to the PMT via imaging light guides consisting of acrylic optical fibers

The effects of Earth's magnetic field on 3-inch diameter photomultipliers used in KM3NeT neutrino telescope

Directory of Open Access Journals (Sweden)

Giordano V.

2016-01-01

Full Text Available The KM3NeT neutrino telescope will be the largest underwater neutrino telescope and will be located in the abyss of the Mediterranean Sea. In neutrino telescopes the key element of the detector is the optical module and for KM3NeT it consists of 31 PMTs stored inside a transparent pressure-resistant glass sphere of 17-inch that serves as mechanical protection while ensuring good light transmission. Since the PMTs installed into an underwater neutrino telescope can change their orientation because of movements of the detector structure due to sea currents, the influence of Earth's magnetic field has been investigated. Magnetic shielding by means of a mu-metal cage is used to reduce magnetic effects and to make the response of the PMT sufficiently orientation independent. In order to quantify the effect on magnetic field, we compared measurements on variation of gain, transit time spread and detection efficiency for a 3-inch PMT in shielded and unshielded condition at 3 PMT inclinations. Data shows that variations are sufficiently low especially for timing properties.

High quality single atomic layer deposition of hexagonal boron nitride on single crystalline Rh(111) four-inch wafers

Energy Technology Data Exchange (ETDEWEB)

Hemmi, A.; Bernard, C.; Cun, H.; Roth, S.; Klöckner, M.; Kälin, T.; Osterwalder, J.; Greber, T., E-mail: greber@physik.uzh.ch [Physik-Institut, Universität Zürich, CH-8057 Zürich (Switzerland); Weinl, M.; Gsell, S.; Schreck, M. [Institut für Physik, Universität Augsburg, D-86135 Augsburg (Germany)

2014-03-15

The setup of an apparatus for chemical vapor deposition (CVD) of hexagonal boron nitride (h-BN) and its characterization on four-inch wafers in ultra high vacuum (UHV) environment is reported. It provides well-controlled preparation conditions, such as oxygen and argon plasma assisted cleaning and high temperature annealing. In situ characterization of a wafer is accomplished with target current spectroscopy. A piezo motor driven x-y stage allows measurements with a step size of 1 nm on the complete wafer. To benchmark the system performance, we investigated the growth of single layer h-BN on epitaxial Rh(111) thin films. A thorough analysis of the wafer was performed after cutting in atmosphere by low energy electron diffraction, scanning tunneling microscopy, and ultraviolet and X-ray photoelectron spectroscopies. The apparatus is located in a clean room environment and delivers high quality single layers of h-BN and thus grants access to large area UHV processed surfaces, which had been hitherto restricted to expensive, small area single crystal substrates. The facility is versatile enough for customization to other UHV-CVD processes, e.g., graphene on four-inch wafers.

Gear bearing drive

Science.gov (United States)

Mavroidis, Constantinos (Inventor); Vranish, John M. (Inventor); Weinberg, Brian (Inventor)

2011-01-01

A gear bearing drive provides a compact mechanism that operates as an actuator providing torque and as a joint providing support. The drive includes a gear arrangement integrating an external rotor DC motor within a sun gear. Locking surfaces maintain the components of the drive in alignment and provide support for axial loads and moments. The gear bearing drive has a variety of applications, including as a joint in robotic arms and prosthetic limbs.

Hostility, driving anger, and dangerous driving: the emerging role of hemispheric preference.

Science.gov (United States)

Gidron, Yori; Gaygısız, Esma; Lajunen, Timo

2014-12-01

Various studies have implicated psychosocial variables (e.g., hostility) in risk of dangerous driving and traffic accidents. However, whether these variables are related to more basic neurobiological factors, and whether such associations have implications for the modification of psychosocial risk factors in the context of driving, have not been examined in depth. This study examined the relationship between hemispheric preference (HP), hostility and self-reported dangerous driving, and the ability to affect driving anger via hemisphere activating cognitive exercises (HACE). In Study 1, 254 Turkish students completed questionnaires of hostility, HP and driving behavior. In Study 2, we conducted a "proof of concept" experimental study, and tested effects of left, right and neutral HACE on driving anger, by exposing N=650 Turkish students to written scenarios including either logical (left hemisphere), visuo-spatial (right hemisphere) or "mild doses" of both types of contents (control). In Study 1, left-HP was associated with higher hostility and with more dangerous driving, and hostility mediated the relationship between L-HP and reported driving behavior. In Study 2, only right-HACE led to immediate significant reductions in self-reported driving anger. Left-HP is related to hostility and to dangerous driving, and it may be possible to partly reduce driving anger by right-HACE. Future studies must replicate these findings with objective measures, more enduring interventions and longer follow-ups. Copyright © 2014. Published by Elsevier Ltd.

Assessment of driving-related performance in chronic whiplash using an advanced driving simulator.

Science.gov (United States)

Takasaki, Hiroshi; Treleaven, Julia; Johnston, Venerina; Rakotonirainy, Andry; Haines, Andrew; Jull, Gwendolen

2013-11-01

Driving is often nominated as problematic by individuals with chronic whiplash associated disorders (WAD), yet driving-related performance has not been evaluated objectively. The purpose of this study was to test driving-related performance in persons with chronic WAD against healthy controls of similar age, gender and driving experience to determine if driving-related performance in the WAD group was sufficiently impaired to recommend fitness to drive assessment. Driving-related performance was assessed using an advanced driving simulator during three driving scenarios; freeway, residential and a central business district (CBD). Total driving duration was approximately 15min. Five driving tasks which could cause a collision (critical events) were included in the scenarios. In addition, the effect of divided attention (identify red dots projected onto side or rear view mirrors) was assessed three times in each scenario. Driving performance was measured using the simulator performance index (SPI) which is calculated from 12 measures. z-Scores for all SPI measures were calculated for each WAD subject based on mean values of the control subjects. The z-scores were then averaged for the WAD group. A z-score of ≤-2 indicated a driving failing grade in the simulator. The number of collisions over the five critical events was compared between the WAD and control groups as was reaction time and missed response ratio in identifying the red dots. Seventeen WAD and 26 control subjects commenced the driving assessment. Demographic data were comparable between the groups. All subjects completed the freeway scenario but four withdrew during the residential and eight during the CBD scenario because of motion sickness. All scenarios were completed by 14 WAD and 17 control subjects. Mean z-scores for the SPI over the three scenarios was statistically lower in the WAD group (-0.3±0.3; Pdriving. There were no differences in the reaction time and missed response ratio in divided

Testing of one-inch UF{sub 6} cylinder valves under simulated fire conditions

Energy Technology Data Exchange (ETDEWEB)

Elliott, P.G. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

1991-12-31

Accurate computational models which predict the behavior of UF{sub 6} cylinders exposed to fires are required to validate existing firefighting and emergency response procedures. Since the cylinder valve is a factor in the containment provided by the UF{sub 6} cylinder, its behavior under fire conditions has been a necessary assumption in the development of such models. Consequently, test data is needed to substantiate these assumptions. Several studies cited in this document provide data related to the behavior of a 1-inch UF{sub 6} cylinder valve in fire situations. To acquire additional data, a series of tests were conducted at the Paducah Gaseous Diffusion Plant (PGDP) under a unique set of test conditions. This document describes this testing and the resulting data.

Test-retest reliability of the driving habits questionnaire in older self-driving adults.

Science.gov (United States)

Song, Chiang-Soon; Chun, Byung-Yoon; Chung, Hyun-Sook

2015-11-01

[Purpose] The purpose of this study was to investigate the test-retest reliability of the Driving Habits Questionnaire in community-dwelling older self-drivers. [Subjects and Methods] Seventy-four participants were recruited by convenience sampling from local rehabilitation centers. This was a cross-sectional study design that used two clinical measures: the Driving Habits Questionnaire and Mini-mental State Examination. To examine the test-retest reliability of the Driving Habits Questionnaire, the clinical tool was measured twice, five days apart. [Results] The Driving Habits Questionnaire showed good reliability for older community-dwelling self-drivers. The Cronbach's alpha coefficients for the four domains of dependence (0.572), difficulty (0.871), crashes and citations (0.689), and driving space (0.961) of the Driving Habits Questionnaire indicated good or high internal consistency. Driving difficulty correlated significantly with self-reported crashes and citations and driving space. [Conclusion] The results of this study suggest that the Driving Habits Questionnaire is a reliable measure of self-reported interview-based driving behavior in the community-dwelling elderly.

Safe driving for teens

Science.gov (United States)

Driving and teenagers; Teens and safe driving; Automobile safety - teenage drivers ... months before taking friends as passengers. Teenage-related driving deaths occur more often in certain conditions. OTHER SAFETY TIPS FOR TEENS Reckless driving is still a ...

Distracted Driving

Science.gov (United States)

... and increased awareness of distracted driving using radio advertisements, news stories, and similar media. After the projects ... available at www.trafficsafetymarketing.gov . Distracted Driving Enforcement – TV Ads (Paid). For re-tagging, go to: www. ...

A study on the effects of fatigue driving and drunk driving on drivers' physical characteristics.

Science.gov (United States)

Zhang, Xingjian; Zhao, Xiaohua; Du, Hongji; Rong, Jian

2014-01-01

The purpose of this study was to analyze the effects of fatigue driving and drunk driving on drivers' physical characteristics; to analyze the differences in drivers' physical characteristics affected by different kinds of fatigue; and to compare the differences in the effects of the 2 driving states, fatigue driving and drunk driving. Twenty-five participants' physical characteristics were collected under 5 controlled situations: normal, tired driving, drowsy driving, drowsiness + tired driving, and drunk driving. In this article, fatigue driving refers to tiredness and drowsiness and includes 3 situations: tired driving, drowsy driving, and drowsiness + tired driving. The drivers' physical characteristics were measured in terms of 9 parameters: systolic blood pressure (SBP), heart rate (HR), eyesight, dynamic visual acuity (DVA), time for dark adaption (TDA), reaction time to sound (RTS), reaction time to light (RTL), deviation of depth perception (DDP), and time deviation of speed anticipation (TDSA). They were analyzed using analysis of variance (ANOVA) with repeated measures. Binary logistical regression analysis was used to explain the relationship between drivers' physical characteristics and the two driving states. Most of the drivers' physical characteristic parameters were found to be significantly different under the influence of different situations. Four indicators are significantly affected by fatigue driving during deep fatigue (in decreasing order of influence): HR, RTL, SBP and RTS. HR and RTL are significant in the logistical regression model of the drowsiness + tired driving situation and normal situations. Six indicators of the drivers' physical characteristics are significantly affected by drunk driving (in decreasing order of influence): SBP, RTL, DDP, eyesight, RTS, and TDSA. SBP and DDP have a significant effect in the logistical regression model of the drunk driving situation and the normal situation. Both fatigue driving and drunk driving

Nanomanipulation of 2 inch wafer fabrication of vertically aligned carbon nanotube arrays by nanoimprint lithography

DEFF Research Database (Denmark)

Bu, Ian Y. Y.; Eichhorn, Volkmar; Carlson, Kenneth

2011-01-01

Carbon nanotube (CNT) arrays are typically defined by electron beam lithography (EBL), and hence limited to small areas due to the low throughput. To obtain wafer‐scale fabrication we propose large area thermal nanoimprint lithography (NIL). A 2‐inch stamp master is defined using EBL for subsequent......, efficient production of wafer‐scale/larger arrays of CNTs has been achieved. The CNTs have been deposited by wafer‐scale plasma enhanced chemical vapour deposition (PECVD) of C2H2/NH3. Substrates containing such nanotubes have been used to automate nanorobotic manipulation sequences of individual CNTs...

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

Distracted driving

Science.gov (United States)

... including maps) The Dangers of Talking on the Phone While Driving You are four times more likely to get ... of reach. If you are caught using a phone while driving, you may risk a ticket or fine. Most ...

Development testing of high temperature bearings for SP-100 control drive assemblies

Science.gov (United States)

Dalcher, Alfred W.; Kjaer-Olsen, Christian G.; Martinez, Carlos; Ogawa, Stanley Y.; Springer, Dwight R.; Yaspo, Robert

1992-01-01

Initial phases of two distinct SP-100 control drive assembly bearing test programs were successfully completed at elevated temperature in vacuum. The first was for the reflector drive line spherical self-aligning bearings. Each bearing consisted of a carbon-graphite ball mounted on an aluminum oxide-coated Ta-10%W shaft, captured by an aluminum oxide-coated Ta-10%W socket. One set of these bearings was exposed to temperatures up to 1180K (1665°F) at 1.33×10-6 Pa (1×10-8 torr) and subjected to 38000 cycles of motion. Friction coefficients were found to be between 0.11 and 0.25 over the full range of operation. Overall performance of the bearings was excellent, with only slight wear observed. The second test program was for the safety rod slider bearing. Zirconium carbide coated Nb-1%Zr bearings pads were stroked inside a molybdenum tube at temperatures up to 1422 K (2100°F) at ˜1.33×10-6 Pa with a normal load of 1.02 Kg between each sliding surface. Coefficients of sliding friction were found to increase from 0.90 at 293 K to 1.20 at 1422 K prior to high temperature dwells. Results were consistent over the range of stroke velocities; 5.1 to 51 mm (0.2 to 2.0 inches) per second. Following dwells of 92, 72, and 110 hours at 1422 K, static friction coefficients as high as 5.4 were observed prior to initiation of sliding, after which sliding friction coefficients of ˜1.6 were seen. Breakaway forces were well within the actuator design limits.

Pipe rupture test results; 4 inch pipe whip tests under BWR operational condition-clearance parameter experiments

International Nuclear Information System (INIS)

Ueda, Syuzo; Isozaki, Toshikuni; Miyazaki, Noriyuki; Kurihara, Ryoichi; Kato, Rokuro; Saito, Kazuo; Miyazono, Shohachiro

1981-05-01

The purpose of pipe rupture studies in JAERI is to perform the model tests on pipe whip, restraint behavior, jet impingement and jet thrust force, and to establish the computational method for analyzing these phenomena. This report describes the experimental results of pipe whip on the pipe specimens of 4 inch in diameter under BWR condition on which the pressure is 6.77 MPa and the temperature is 285 0 C. The pipe specimens were 114.3 mm (4 inch) in diameter and 8.6 mm in thickness and 4500 mm in length. Four pipe whip restraints used in the tests were the U-bar type of 8 mm in diameter and fabricated from type 304 stainless steel. The experimental parameter was the clearance (30, 50 and 100 mm). The dynamic strain behavior of the pipe specimen and the restraints was investigated by strain gages and their residual deformation was obtained by measuring marking points provided on their surface. The Pressure-time history in the pipe specimens was also obtained by pressure gages. The maximum pipe strain is caused near the restraints and increases with increase of the clearance. The experimental results of pipe whip tests indicate the effectiveness of pipe whip restraints. The ratio of absorbed strain energy of the pipe specimen to that of the restraints is nearly constant for different clearances at the overhang length of 400 mm. (author)

Control rod drives

International Nuclear Information System (INIS)

Nakamura, Akira.

1984-01-01

Purpose: To enable to monitor the coupling state between a control rod and a control rod drive. Constitution: After the completion of a control rod withdrawal, a coolant pressure is applied to a control rod drive being adjusted so as to raise only the control rod drive and, in a case where the coupling between the control rod drive and the control rod is detached, the former is elevated till it contacts the control rod and then stopped. The actual stopping position is detected by an actual position detection circuit and compared with a predetermined position stored in a predetermined position detection circuit. If both of the positions are not aligned with each other, it is judged by a judging circuit that the control rod and the control rod drives are not combined. (Sekiya, K.)

Proactive vs. reactive car driving: EEG evidence for different driving strategies of older drivers

Science.gov (United States)

Wascher, Edmund; Getzmann, Stephan

2018-01-01

Aging is associated with a large heterogeneity in the extent of age-related changes in sensory, motor, and cognitive functions. All these functions can influence the performance in complex tasks like car driving. The present study aims to identify potential differences in underlying cognitive processes that may explain inter-individual variability in driving performance. Younger and older participants performed a one-hour monotonous driving task in a driving simulator under varying crosswind conditions, while behavioral and electrophysiological data were recorded. Overall, younger and older drivers showed comparable driving performance (lane keeping). However, there was a large difference in driving lane variability within the older group. Dividing the older group in two subgroups with low vs. high driving lane variability revealed differences between the two groups in electrophysiological correlates of mental workload, consumption of mental resources, and activation and sustaining of attention: Older drivers with high driving lane variability showed higher frontal Alpha and Theta activity than older drivers with low driving lane variability and—with increasing crosswind—a more pronounced decrease in Beta activity. These results suggest differences in driving strategies of older and younger drivers, with the older drivers using either a rather proactive and alert driving strategy (indicated by low driving lane variability and lower Alpha and Beta activity), or a rather reactive strategy (indicated by high driving lane variability and higher Alpha activity). PMID:29352314

The 88-Inch Cyclotron: A One-Stop Facility for Electronics Radiation and Detector Testing

Energy Technology Data Exchange (ETDEWEB)

Kireeff Covo, M.; Albright, R. A.; Ninemire, B. F.; Johnson, M. B.; Hodgkinson, A.; Loew, T.; Benitez, J. Y.; Todd, D. S.; Xie, D. Z.; Perry, T.; Phair, L.; Bernsteiny, L. A.; Bevins, J.; Brown, J. A.; Goldblum, B. L.; Harasty, M.; Harrig, K. P.; Laplace, T. A.; Matthews, E. F.; Bushmaker, A.; Walker, D.; Oklejas, V.; Hopkins, A. R.; Bleuel, D. L.; Chen, J.; Cronin, S. B.

2017-10-01

In outer space down to the altitudes routinely flown by larger aircrafts, radiation can pose serious issues for microelectronics circuits. The 88-Inch Cyclotron at Lawrence Berkeley National Laboratory is a sector-focused cyclotron and home of the Berkeley Accelerator Space Effects Facility, where the effects of energetic particles on sensitive microelectronics are studied with the goal of designing electronic systems for the space community. This paper describes the flexibility of the facility and its capabilities for testing the bombardment of electronics by heavy ions, light ions, and neutrons. Experimental capabilities for the generation of neutron beams from deuteron breakups and radiation testing of carbon nanotube field effect transistor will be discussed.

Simple Driving Techniques

DEFF Research Database (Denmark)

Rosendahl, Mads

2002-01-01

-like language. Our aim is to extract a simple notion of driving and show that even in this tamed form it has much of the power of more general notions of driving. Our driving technique may be used to simplify functional programs which use function composition and will often be able to remove intermediate data...

Analysis of ATLAS 6-inch cold leg break simulation with MARS-KS code

Energy Technology Data Exchange (ETDEWEB)

Kim, Se Yun; Jun, Hwang Yong; Ha, Sang Jun [Korea Electric Power Company, Daejeon (Korea, Republic of)

2011-05-15

A Domestic Standard Problem (DSP) exercise using ATLAS facility has been organized by KAERI. As the second DSP exercise, the 6-inch cold leg bottom break was determined. This experiment is the counterpart test to the DVI line break to verify the safety performance of the DVI method over the traditional CLI method. Compared with the large break LOCA, the phases of the small break LOCA prior to core recovery occur over a long period. The blowdown, natural circulation, loop seal clearance, boil-off, and core recovery phase should be investigated minutely with relevant models of safety analysis codes in order to predict these thermal hydraulic phenomena correctly. To investigate the ECC bypass phenomena, a finer study on the thermalhydraulic behavior in upper annulus downcomer was carried out

Performance differences when using 26- and 29-inch-wheel bikes in Swiss National Team cross-country mountain bikers.

Science.gov (United States)

Steiner, Thomas; Müller, Beat; Maier, Thomas; Wehrlin, Jon Peter

2016-08-01

The purpose of this study was to analyse the effect of bike type - the 26-inch-wheel bike (26" bike) and the 29-inch-wheel bike (29" bike) - on performance in elite mountain bikers. Ten Swiss National Team athletes (seven males, three females) completed six trials with individual start on a simulated cross-country course with 35 min of active recovery between trials (three trials on a 26" bike and three trials on a 29" bike, alternate order, randomised start-bike). The course consisted of two separate sections expected to favour either the 29" bike (section A) or the 26" bike (section B). For each trial performance, power output, cadence and heart rate were recorded and athletes' experiences were documented. Mean overall performance (time: 304 ± 27 s vs. 311 ± 29 s; P < 0.01) and performance in sections A (P < 0.001) and B (P < 0.05) were better when using the 29" bike. No significant differences were observed for power output, cadence or heart rate. Athletes rated the 29" bike as better for performance in general, passing obstacles and traction. The 29" bike supports superior performance for elite mountain bikers, even on sections supposed to favour the 26" bike.

Driving and dementia: Efficient approach to driving safety concerns in family practice.

Science.gov (United States)

Lee, Linda; Molnar, Frank

2017-01-01

To provide primary care physicians with an approach to driving safety concerns when older persons present with memory difficulties. The approach is based on an accredited memory clinic training program developed by the Centre for Family Medicine Primary Care Collaborative Memory Clinic. One of the most challenging aspects of dementia care is the assessment of driving safety. Drivers with dementia are at higher risk of motor vehicle collisions, yet many drivers with mild dementia might be safely able to continue driving for several years. Because safe driving is dependent on multiple cognitive and functional skills, clinicians should carefully consider many factors when determining if cognitive concerns affect driving safety. Specific findings on corroborated history and office-based cognitive testing might aid in the physician's decisions to refer for comprehensive on-road driving evaluation and whether to notify transportation authorities in accordance with provincial reporting requirements. Sensitive communication and a person-centred approach are essential. Primary care physicians must consider many factors when determining if cognitive concerns might affect driving safety in older drivers. Copyright© the College of Family Physicians of Canada.

The relationship between impaired driving crashes and beliefs about impaired driving: do residents in high crash rate counties have greater concerns about impaired driving?

Science.gov (United States)

Beck, Kenneth H; Yan, Alice F; Wang, Min Qi; Kerns, Timothy J; Burch, Cynthia A

2009-04-01

The purpose of this investigation was to examine the relationship between impaired driving crashes and public beliefs and concerns about impaired driving across each of Maryland's twenty-four counties (including Baltimore City). It was hypothesized that residents of counties that experience higher impaired driving crashes would express more concerns about impaired driving and perceive more risks about driving impaired than residents of counties that have lower rates of impaired driving. Data for alcohol impaired driving crashes were obtained for the years 2004-2006. These data were compared to public opinion data that was obtained annually by random-digit-dial telephone surveys from 2004 to 2007. Concerns about drunk driving as well as perceptions of the likelihood of being stopped by the police if one were to drive after having too much to drink were related to counties with higher serious impaired driving crash rates, as were perceptions that the police and the legal system were too lenient. Perceptions about the likelihood of being stopped by the police were higher in those counties with more impaired driving enforcement activity. Perceptions of concern appear to be shaped more by crash exposure than enforcement activity. Campaigns that address impaired driving prevention should substantially increase enforcement, strengthen the adjudication process of impaired drivers, and emphasize the potential seriousness of drinking-driving crashes in their promotional activities.

Design evaluation of the 20-cm (8-inch) secondary burner system

International Nuclear Information System (INIS)

Rode, J.S.

1977-08-01

This report describes an evaluation of the design of the existing 20-cm (8-inch) engineering-scale secondary burner system in the HTGR reprocessing cold pilot plant at General Atomic Co. The purpose of this evaluation is to assess the suitability of the existing design as a prototype of the HTGR Recycle Demonstration Facility (HRDF) secondary burner system and to recommend alternatives where the existing design is thought to be unsuitable as a prototype. This evaluation has led to recommendations for the parallel development of two integrated design concepts for a prototype secondary burner system. One concept utilizes the existing burner heating and cooling subsystems in order to minimize development risk, but simplifies a number of other features associated with remote maintenance and burner operation. The other concept, which offers maximum cost reduction, utilizes internal gas cooling of the burner, retains the existing heating subsystem for design compatibility, but requires considerable development to reduce the risk to acceptable limits. These concepts, as well as other design alternatives, are described and evaluated

Nuclear refueling platform drive system

International Nuclear Information System (INIS)

Busch, F.R.; Faulstich, D.L.

1992-01-01

This patent describes a drive system. It comprises: a gantry including a bridge having longitudinal and transverse axes and supported by spaced first and second end frames joined to fist and second end frames joined to first and second drive trucks for moving the bridge along the transverse axis; first means for driving the first drive truck; second means for driving the second drive truck being independent from the first driving means; and means for controlling the first and second driving means for reducing differential transverse travel between the first and second drive trucks, due to a skewing torque acting on the bridge, to less than a predetermined maximum, the controlling means being in the form of an electrical central processing unit and including: a closed-loop first velocity control means for controlling velocity of the first drive truck by providing a first command signal to the first driver means; a close loop second velocity control means for controlling velocity of the second drive truck by providing a second command signal to the second driving means; and an auxiliary closed-loop travel control means

Dementia and driving.

Science.gov (United States)

O'Neill, D; Neubauer, K; Boyle, M; Gerrard, J; Surmon, D; Wilcock, G K

1992-04-01

Many European countries test cars, but not their drivers, as they age. There is evidence to suggest that human factors are more important than vehicular factors as causes of motor crashes. The elderly also are involved in more accidents per distance travelled than middle-aged drivers. As the UK relies on self-certification of health by drivers over the age of 70 years, we examined the driving practices of patients with dementia attending a Memory Clinic. Nearly one-fifth of 329 patients with documented dementia continued to drive after the onset of dementia, and impaired driving ability was noted in two-thirds of these. Their families experienced great difficulty in persuading patients to stop driving, and had to invoke outside help in many cases. Neuropsychological tests did not help to identify those who drove badly while activity of daily living scores were related to driving ability. These findings suggest that many patients with dementia drive in an unsafe fashion after the onset of the illness. The present system of self-certification of health by the elderly for driver-licensing purposes needs to be reassessed.

Dialling and driving: factors influencing intentions to use a mobile phone while driving.

Science.gov (United States)

Walsh, Shari P; White, Katherine M; Hyde, Melissa K; Watson, Barry

2008-11-01

Despite being identified as an unsafe (and, in some jurisdictions, illegal) driving practice, the psychological factors underlying people's decision to use their mobile phone while driving have received little attention. The present study utilised the theory of planned behaviour (TPB) to examine the role of attitudes, norms, control factors, and risk perceptions, in predicting people's intentions to use their mobile phone while driving. We examined the predictors of intentions to use a mobile phone while driving in general, and for calling and text messaging in 4 scenarios differing in descriptions of vehicle speed and time pressure. There was some support for the TPB given that attitudes consistently predicted intentions to drive while using a mobile phone and that pressure from significant others (norms) determined some phone use while driving intentions, although less support was found for the role of perceptions of control. Risk was not generally predictive of safer driving intentions. These findings indicate that different factors influence each form of mobile phone use while driving and, hence, a multi-strategy approach is likely to be required to address the issue.

Relationships between frequency of driving under the influence of cannabis, self-reported reckless driving and risk-taking behavior observed in a driving simulator.

Science.gov (United States)

Bergeron, Jacques; Paquette, Martin

2014-06-01

The role of cannabis consumption in traffic crashes is unclear and the causal link between cannabis and collisions is still to be demonstrated. While cannabis use is very likely to impair driving ability, there is as yet no overwhelming evidence that cannabis use in isolation contributes more to collisions than other characteristics inherent to cannabis users. As noted in a growing body of literature, individuals driving under the influence of cannabis (DUIC) seem to exhibit a general reckless driving style putting them at higher risk to be involved in traffic crashes. This study aims at investigating the relationship between self-reported DUIC and reckless driving by means of self-reported measures and direct observations made in a driving simulator. Participants (n=72) were required to be between 18 and 25 years of age, to hold a valid driver's license, and to drive at least twice a week. They completed standard driving simulation tasks recreating everyday on-road trivial conditions. Results show that people admitting that they commit more real-life dangerous driving behaviors reached higher maximum speed and demonstrated more reckless driving behaviors on the driving simulation tasks. Self-reported DUIC is associated with a risky driving style including a broad range of reckless on-road behaviors and support the problem driving behavior theory. Moreover, beyond confounding factors, both self-report DUIC and observed dangerous behaviors are associated with real-life traffic violations. Since DUIC appears to be related to an overall reckless style of driving, it is proposed that public safety policies should be more holistic, simultaneously targeting multiple on-road dangerous behaviors for intervention. Copyright © 2014 Elsevier B.V. All rights reserved.

Cognitive impairment and driving safety.

Science.gov (United States)

Eby, David W; Molnar, Lisa J

2012-11-01

As the populations of many countries continue to age, cognitive impairment will likely become more common. Individuals with cognitive impairment pose special challenges for families, health professionals, driving safety professionals, and the larger community, particularly if these older adults depend on driving as their primary means of community mobility. It is vital that we continue to extend our knowledge about the driving behavior of individuals' with cognitive impairment, as well as try to develop effective means of screening and assessing these individuals for fitness to drive and help facilitate their transition to non-driving when appropriate. This special issue is intended to provide researchers and practitioners an opportunity to present the most recent research findings on driving-related issues among older adults with cognitive impairment. The issue contains 11 original contributions from seven countries. The topics covered by these papers are: crash risks; screening, assessment, and fitness to drive; driving performance using a driving simulator; and driving behaviors and driving-related decisions of people with cognitive impairments. Copyright © 2012. Published by Elsevier Ltd.

State all-driver distracted driving laws and high school students'  texting while driving behavior.

Science.gov (United States)

Qiao, Nan; Bell, Teresa Maria

2016-01-01

Texting while driving is highly prevalent among adolescents and young adults in the United States. Texting while driving can significantly increase the risk of road crashes and is associated with other risky driving behaviors. Most states have enacted distracted driving laws to prohibit texting while driving. This study examines effects of different all-driver distracted driving laws on texting while driving among high school students. High school student data were extracted from the 2013 National Youth Risk Behavior Survey. Distracted driving law information was collected from the National Conference of State Legislatures. The final sample included 6,168 high school students above the restricted driving age in their states and with access to a vehicle. Logistic regression was applied to estimate odds ratios of laws on texting while driving. All-driver text messaging bans with primary enforcement were associated with a significant reduction in odds of texting while driving among high school students (odds ratio = 0.703; 95% confidence interval, 0.513-0.964), whereas all-driver phone use bans with primary enforcement did not have a significant association with texting while driving (odds ratio = 0.846; 95% confidence interval, 0.501-1.429). The findings indicate that all-driver distracted driving laws that specifically target texting while driving as opposed to all types of phone use are effective in reducing the behavior among high school students.

Using driving simulators to assess driving safety.

Science.gov (United States)

Boyle, Linda Ng; Lee, John D

2010-05-01

Changes in drivers, vehicles, and roadways pose substantial challenges to the transportation safety community. Crash records and naturalistic driving data are useful for examining the influence of past or existing technology on drivers, and the associations between risk factors and crashes. However, they are limited because causation cannot be established and technology not yet installed in production vehicles cannot be assessed. Driving simulators have become an increasingly widespread tool to understand evolving and novel technologies. The ability to manipulate independent variables in a randomized, controlled setting also provides the added benefit of identifying causal links. This paper introduces a special issue on simulator-based safety studies. The special issue comprises 25 papers that demonstrate the use of driving simulators to address pressing transportation safety problems and includes topics as diverse as neurological dysfunction, work zone design, and driver distraction. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

The Technique of Changing the Drive Method of Micro Step Drive and Sensorless Drive for Hybrid Stepping Motor

Science.gov (United States)

Yoneda, Makoto; Dohmeki, Hideo

The position control system with the advantage large torque, low vibration, and high resolution can be obtained by the constant current micro step drive applied to hybrid stepping motor. However loss is large, in order not to be concerned with load torque but to control current uniformly. As the one technique of a position control system in which high efficiency is realizable, the same sensorless control as a permanent magnet motor is effective. But, it was the purpose that the control method proposed until now controls speed. Then, this paper proposed changing the drive method of micro step drive and sensorless drive. The change of the drive method was verified from the simulation and the experiment. On no load, it was checked not producing change of a large speed at the time of a change by making electrical angle and carrying out zero reset of the integrator. On load, it was checked that a large speed change arose. The proposed system could change drive method by setting up the initial value of an integrator using the estimated result, without producing speed change. With this technique, the low loss position control system, which employed the advantage of the hybrid stepping motor, has been built.

High-risk driving attitudes and everyday driving violations of car and racing enthusiasts in Ontario, Canada.

Science.gov (United States)

Yildirim-Yenier, Zümrüt; Vingilis, Evelyn; Wiesenthal, David L; Mann, Robert E; Seeley, Jane

2015-01-01

Attitudes and individual difference variables of car and racing enthusiasts regarding high-risk behaviors of street racing and stunt driving have recently been investigated. Positive attitudes toward high-risk driving, personality variables such as driver thrill seeking, and other self-reported risky driving acts were associated with these behaviors. However, probable relationships among high-risk driving tendencies, everyday driving behaviors, and negative road safety outcomes have remained largely unexamined. This study aimed to investigate the associations among car and racing enthusiasts' high-risk driving attitudes, self-reported everyday driving violations (i.e., ordinary and aggressive violations), and self-reported negative outcomes (i.e., collisions and driving offense citations). A web-based survey was conducted with members and visitors of car club and racing websites in Ontario, Canada. Data were obtained from 366 participants. The questionnaire included 4 attitude measures-(1) attitudes toward new penalties for Ontario's Street Racers, Stunt and Aggressive Drivers Legislation; (2) attitudes toward new offenses of stunt driving under the same legislation; (3) general attitudes toward street racing and stunt driving; (4) comparison of street racing with other risky driving behaviors-self-reported driving violations (i.e., ordinary and aggressive violations); self-reported collisions and offense citations; and background and driving questions (e.g., age, driving frequency). Results revealed that attitudes toward stunt driving offenses negatively and general attitudes toward street racing and stunt driving positively predicted ordinary violations, which, in turn, predicted offense citations. Moreover, general attitudes toward street racing and stunt driving positively predicted aggressive violations, which, in turn, predicted offense citations. The findings indicate that positive high-risk driving attitudes may be transferring to driving violations in

Parkinson's disease and driving ability

Science.gov (United States)

Singh, Rajiv; Pentland, Brian; Hunter, John; Provan, Frances

2007-01-01

Objectives To explore the driving problems associated with Parkinson's disease (PD) and to ascertain whether any clinical features or tests predict driver safety. Methods The driving ability of 154 individuals with PD referred to a driving assessment centre was determined by a combination of clinical tests, reaction times on a test rig and an in‐car driving test. Results The majority of cases (104, 66%) were able to continue driving although 46 individuals required an automatic transmission and 10 others needed car modifications. Ability to drive was predicted by the severity of physical disease, age, presence of other associated medical conditions, particularly dementia, duration of disease, brake reaction, time on a test rig and score on a driving test (all pautomatic transmission. A combination of clinical tests and in‐car driving assessment will establish safety to drive, and a number of clinical correlates can be shown to predict the likely outcome and may assist in the decision process. This is the largest series of consecutive patients seen at a driving assessment centre reported to date, and the first to devise a scoring system for on‐road driving assessment. PMID:17178820

Rod drive and latching mechanism

International Nuclear Information System (INIS)

Veronesi, L.; Sherwood, D.G.

1982-01-01

Hydraulic drive and latching mechanisms for driving reactivity control mechanisms in nuclear reactors are described. Preferably, the pressurized reactor coolant is utilized to raise the drive rod into contact with and to pivot the latching mechanism so as to allow the drive rod to pass the latching mechanism. The pressure in the housing may then be equalized which allows the drive rod to move downwardly into contact with the latching mechanism but to hold the shaft in a raised position with respect to the reactor core. Once again, the reactor coolant pressure may be utilized to raise the drive rod and thus pivot the latching mechanism so that the drive rod passes above the latching mechanism. Again, the mechanism pressure can be equalized which allows the drive rod to fall and pass by the latching mechanism so that the drive rod approaches the reactor core. (author)

Driving range estimation for electric vehicles based on driving condition identification and forecast

Science.gov (United States)

Pan, Chaofeng; Dai, Wei; Chen, Liao; Chen, Long; Wang, Limei

2017-10-01

With the impact of serious environmental pollution in our cities combined with the ongoing depletion of oil resources, electric vehicles are becoming highly favored as means of transport. Not only for the advantage of low noise, but for their high energy efficiency and zero pollution. The Power battery is used as the energy source of electric vehicles. However, it does currently still have a few shortcomings, noticeably the low energy density, with high costs and short cycle life results in limited mileage compared with conventional passenger vehicles. There is great difference in vehicle energy consumption rate under different environment and driving conditions. Estimation error of current driving range is relatively large due to without considering the effects of environmental temperature and driving conditions. The development of a driving range estimation method will have a great impact on the electric vehicles. A new driving range estimation model based on the combination of driving cycle identification and prediction is proposed and investigated. This model can effectively eliminate mileage errors and has good convergence with added robustness. Initially the identification of the driving cycle is based on Kernel Principal Component feature parameters and fuzzy C referring to clustering algorithm. Secondly, a fuzzy rule between the characteristic parameters and energy consumption is established under MATLAB/Simulink environment. Furthermore the Markov algorithm and BP(Back Propagation) neural network method is utilized to predict the future driving conditions to improve the accuracy of the remaining range estimation. Finally, driving range estimation method is carried out under the ECE 15 condition by using the rotary drum test bench, and the experimental results are compared with the estimation results. Results now show that the proposed driving range estimation method can not only estimate the remaining mileage, but also eliminate the fluctuation of the

Medications and impaired driving.

Science.gov (United States)

Hetland, Amanda; Carr, David B

2014-04-01

To describe the association of specific medication classes with driving outcomes and provide clinical recommendations. The MEDLINE and EMBASE databases were searched for articles published from January 1973 to June 2013 on classes of medications associated with driving impairment. The search included outcome terms such as automobile driving, motor vehicle crash, driving simulator, and road tests. Only English-language articles that contained findings from observational or interventional designs with ≥ 10 participants were included in this review. Cross-sectional studies, case series, and case reports were excluded. Driving is an important task and activity for the majority of adults. Some commonly prescribed medications have been associated with driving impairment measured by road performance, driving simulation, and/or motor vehicle crashes. This review of 30 studies identified findings with barbiturates, benzodiazepines, hypnotics, antidepressants, opioid and nonsteroidal analgesics, anticonvulsants, antipsychotics, antiparkinsonian agents, skeletal muscle relaxants, antihistamines, anticholinergic medications, and hypoglycemic agents. Additional studies of medication impact on sedation, sleep latency, and psychomotor function, as well as the role of alcohol, are also discussed. Psychotropic agents and those with central nervous system side effects were associated with measures of impaired driving performance. It is difficult to determine if such associations are actually a result of medication use or the medical diagnosis itself. Regardless, clinicians should be aware of the increased risk of impaired driving with specific classes of medications, educate their patients, and/or consider safer alternatives.

In Patients With Cirrhosis, Driving Simulator Performance Is Associated With Real-life Driving.

Science.gov (United States)

Lauridsen, Mette M; Thacker, Leroy R; White, Melanie B; Unser, Ariel; Sterling, Richard K; Stravitz, Richard T; Matherly, Scott; Puri, Puneet; Sanyal, Arun J; Gavis, Edith A; Luketic, Velimir; Siddiqui, Muhammad S; Heuman, Douglas M; Fuchs, Michael; Bajaj, Jasmohan S

2016-05-01

Minimal hepatic encephalopathy (MHE) has been linked to higher real-life rates of automobile crashes and poor performance in driving simulation studies, but the link between driving simulator performance and real-life automobile crashes has not been clearly established. Furthermore, not all patients with MHE are unsafe drivers, but it is unclear how to distinguish them from unsafe drivers. We investigated the link between performance on driving simulators and real-life automobile accidents and traffic violations. We also aimed to identify features of unsafe drivers with cirrhosis and evaluated changes in simulated driving skills and MHE status after 1 year. We performed a study of outpatients with cirrhosis (n = 205; median 55 years old; median model for end-stage liver disease score, 9.5; none with overt hepatic encephalopathy or alcohol or illicit drug use within previous 6 months) seen at the Virginia Commonwealth University and McGuire Veterans Administration Medical Center, from November 2008 through April 2014. All participants were given paper-pencil tests to diagnose MHE (98 had MHE; 48%), and 163 patients completed a standardized driving simulation. Data were collected on traffic violations and automobile accidents from the Virginia Department of Motor Vehicles and from participants' self-assessments when they entered the study, and from 73 participants 1 year later. Participants also completed a questionnaire about alcohol use and cessation patterns. The driving simulator measured crashes, run-time, road center and edge excursions, and illegal turns during navigation; before and after each driving simulation session, patients were asked to rate their overall driving skills. Drivers were classified as safe or unsafe based on crashes and violations reported on official driving records; simulation results were compared with real-life driving records. Multivariable regression analyses of real-life crashes and violations was performed using data on

Correspondence between Simulator and On-Road Drive Performance: Implications for Assessment of Driving Safety.

Science.gov (United States)

Aksan, Nazan; Hacker, Sarah D; Sager, Lauren; Dawson, Jeffrey; Anderson, Steven; Rizzo, Matthew

2016-03-01

Forty-two younger (Mean age = 35) and 37 older drivers (Mean age = 77) completed four similar simulated drives. In addition, 32 younger and 30 older drivers completed a standard on-road drive in an instrumented vehicle. Performance in the simulated drives was evaluated using both electronic drive data and video-review of errors. Safety errors during the on-road drive were evaluated by a certified driving instructor blind to simulator performance, using state Department of Transportation criteria. We examined the degree of convergence in performance across the two platforms on various driving tasks including lane change, lane keeping, speed control, stopping, turns, and overall performance. Differences based on age group indicated a pattern of strong relative validity for simulator measures. However, relative rank-order in specific metrics of performance suggested a pattern of moderate relative validity. The findings have implications for the use of simulators in assessments of driving safety as well as its use in training and/or rehabilitation settings.

Superluminal warp drive

Energy Technology Data Exchange (ETDEWEB)

Gonzalez-Diaz, Pedro F. [Colina de los Chopos, Centro de Fisica ' Miguel A. Catalan' , Instituto de Matematicas y Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 121, 28006 Madrid (Spain)], E-mail: p.gonzalezdiaz@imaff.cfmac.csic.es

2007-09-20

In this Letter we consider a warp drive spacetime resulting from that suggested by Alcubierre when the spaceship can only travel faster than light. Restricting to the two dimensions that retains most of the physics, we derive the thermodynamic properties of the warp drive and show that the temperature of the spaceship rises up as its apparent velocity increases. We also find that the warp drive spacetime can be exhibited in a manifestly cosmological form.

The impact of continuous driving time and rest time on commercial drivers' driving performance and recovery.

Science.gov (United States)

Wang, Lianzhen; Pei, Yulong

2014-09-01

This real road driving study was conducted to investigate the effects of driving time and rest time on the driving performance and recovery of commercial coach drivers. Thirty-three commercial coach drivers participated in the study, and were divided into three groups according to driving time: (a) 2 h, (b) 3 h, and (c) 4 h. The Stanford Sleepiness Scale (SSS) was used to assess the subjective fatigue level of the drivers. One-way ANOVA was employed to analyze the variation in driving performance. The statistical analysis revealed that driving time had a significant effect on the subjective fatigue and driving performance measures among the three groups. After 2 h of driving, both the subjective fatigue and driving performance measures began to deteriorate. After 4 h of driving, all of the driving performance indicators changed significantly except for depth perception. A certain amount of rest time eliminated the negative effects of fatigue. A 15-minute rest allowed drivers to recover from a two-hour driving task. This needed to be prolonged to 30 min for driving tasks of 3 to 4 h of continuous driving. Drivers' attention, reactions, operating ability, and perceptions are all affected in turn after over 2 h of continuous driving. Drivers should take a certain amount of rest to recover from the fatigue effects before they continue driving. Copyright © 2014 National Safety Council and Elsevier Ltd. All rights reserved.

Older drivers' self-assessed driving skills, driving-related stress and self-regulation in traffic

DEFF Research Database (Denmark)

Siren, Anu Kristiina; Meng, Annette

2013-01-01

Previous research on older drivers has indicated connections between self-rated driving ability, confidence in their own driving, driving-related stress, and self-regulatory behaviour. However, more systematic associations between older drivers' perceptions on their own driving and self......-regulation or driver stress and self-regulation behaviour, and possible gender differences in these, have not been obtained in previous studies. The aim of the present study was to gain a better understanding of older drivers' self-regulatory driving and the motivators behind this behaviour, by placing this behaviour...... and avoidance than situations related to infrastructure, and women were more likely to report discomfort and avoidance of driving situations. The results suggest that older drivers generally show good self-judgement of changes in their driving skills and acknowledge the different types of skills comprised...

Ion pump as molecular ratchet and effects of noise: electric activation of cation pumping by Na,K-ATPase

Science.gov (United States)

Tsong, T. Y.; Xie, T. D.

2002-08-01

Na,K-ATPase is a universal ion pump of the biological cell. Under physiological conditions, it uses the γ-phosphorus bond energy of ATP during hydrolysis to pump 2 K+ inward and 3 Na+ outward; both being uphill transports. The experiment presented here demonstrates that the protein transporter can also use electric energy to fuel its pump activity. A theory of electroconformational coupling (TEC) is described and an experiment performed to verify several predictions of the model. Analysis based on the TEC model suggests that Na,K-ATPase is a Brownian ratchet. The enzyme harvests energy from the applied field by means of the field-induced conformational oscillation or fluctuation. However, high efficiency of energy transduction can only be achieved with an electric field of certain intensities, frequencies and waveforms. This property of the enzyme allows us to define an electric signal and differentiate it from electric noise on the basis of the analysis by the TEC model. Data show that electric noise alone does not induce pump activity. However, an appropriate power level of noise imposed on a signal can enhance the pump efficiency. The effect of noise on the signal transduction of Na,K-ATPase is reminiscent of the stochastic resonance phenomenon reported in other biological systems [3, 35]. The TEC model embodies many common features of enzymes and biological motors. It is potentially energy-efficient, much more so than models based on the ion-rectification mechanism.

Effects of decades of physical driving on body movement and motion sickness during virtual driving.

Directory of Open Access Journals (Sweden)

Thomas A Stoffregen

Full Text Available We investigated relations between experience driving physical automobiles and motion sickness during the driving of virtual automobiles. Middle-aged individuals drove a virtual automobile in a driving video game. Drivers were individuals who had possessed a driver's license for approximately 30 years, and who drove regularly, while non-drivers were individuals who had never held a driver's license, or who had not driven for more than 15 years. During virtual driving, we monitored movement of the head and torso. During virtual driving, drivers became motion sick more rapidly than non-drivers, but the incidence and severity of motion sickness did not differ as a function of driving experience. Patterns of movement during virtual driving differed as a function of driving experience. Separately, movement differed between participants who later became motion sick and those who did not. Most importantly, physical driving experience influenced patterns of postural activity that preceded motion sickness during virtual driving. The results are consistent with the postural instability theory of motion sickness, and help to illuminate relations between the control of physical and virtual vehicles.

Leveraging Environmental Correlations: The Thermodynamics of Requisite Variety

Science.gov (United States)

Boyd, Alexander B.; Mandal, Dibyendu; Crutchfield, James P.

2017-06-01

Key to biological success, the requisite variety that confronts an adaptive organism is the set of detectable, accessible, and controllable states in its environment. We analyze its role in the thermodynamic functioning of information ratchets—a form of autonomous Maxwellian Demon capable of exploiting fluctuations in an external information reservoir to harvest useful work from a thermal bath. This establishes a quantitative paradigm for understanding how adaptive agents leverage structured thermal environments for their own thermodynamic benefit. General ratchets behave as memoryful communication channels, interacting with their environment sequentially and storing results to an output. The bulk of thermal ratchets analyzed to date, however, assume memoryless environments that generate input signals without temporal correlations. Employing computational mechanics and a new information-processing Second Law of Thermodynamics (IPSL) we remove these restrictions, analyzing general finite-state ratchets interacting with structured environments that generate correlated input signals. On the one hand, we demonstrate that a ratchet need not have memory to exploit an uncorrelated environment. On the other, and more appropriate to biological adaptation, we show that a ratchet must have memory to most effectively leverage structure and correlation in its environment. The lesson is that to optimally harvest work a ratchet's memory must reflect the input generator's memory. Finally, we investigate achieving the IPSL bounds on the amount of work a ratchet can extract from its environment, discovering that finite-state, optimal ratchets are unable to reach these bounds. In contrast, we show that infinite-state ratchets can go well beyond these bounds by utilizing their own infinite "negentropy". We conclude with an outline of the collective thermodynamics of information-ratchet swarms.

Driving competences and neuropsychological factors associated to driving counseling in multiple sclerosis.

Science.gov (United States)

Badenes, Dolors; Garolera, Maite; Casas, Laura; Cejudo-Bolivar, Juan Carlos; de Francisco, Jorge; Zaragoza, Silvia; Calzado, Noemi; Aguilar, Miquel

2014-05-01

Multiple Sclerosis (MS) significantly impacts daily living activities, including car driving. To investigate driving difficulties experienced with MS, we compared 50 MS patients with minor or moderate disability and 50 healthy controls (HC) using computerized driving tests (the ASDE driver test and the Useful Field of View (UFOV) test) and neuropsychological tests. Inclusion criteria included being active drivers. We evaluated whether cognitive deterioration in MS is associated with the results of driving tests by comparing MS patients without cognitive deterioration with HC. The results indicated that the MS patients performed worse than the HCs in attention, information processing, working memory and visuomotor coordination tasks. Furthermore, MS patients with cognitive impairments experienced more difficulties in the driving tests than did the non-impaired MS patients. Motor dysfunction associated with MS also played an important role in this activity. The results of this study suggest that MS should be assessed carefully and that special emphasis should be placed on visuomotor coordination and executive functions because patients with minor motor disability and subtle cognitive impairments can pass measures predictive of driving safety.

Perception of the Risks Associated with Impaired Driving and Effects on Driving Behavior

OpenAIRE

Georges Dionne; Claude Fluet; Denise Desjardins

2006-01-01

This research studies the perception of the risks associated with impaired driving-probability of being apprehended or of having an accident-and the relation between the perception of risks and driving behavior. The most important determinants of perceptual biases are age, an accumulation of violations in the year preceding the survey, being a non-drinker, knowledge of the legal alcohol limit for driving, opinion about zero tolerance for impaired driving, and family income. Perceptual biases ...

Epilepsy and driving

Directory of Open Access Journals (Sweden)

Matej Mavrič

2015-05-01

Full Text Available Epilepsy poses a risk for all participants in road traffic; therefore people with epilepsy do not meet the criteria for an unlimited driving license. Their driving is affected not only by epileptic seizures causing impaired consciousness and involuntary movements, but also by antiepileptic drugs with their many unwanted affects. The experts have not yet agreed on whether people with epilepsy have an increased risk of experiencing a road traffic accident. However, recent data suggests that the overall risk is lower compared to other medical conditions. Scientific evidence forms the basis of legislation, which by limiting people with epilepsy, enables all participants in road traffic to drive in the safest possible environment. The legislation that governs epilepsy and driving in Slovenia has been recently thoroughly reformed and thus allows a less discriminatory management of people with epilepsy. Although people with epilepsy experience many issues in their daily life, including their personal relationships and employment, they often list the need for driving as a top concern in surveys. General physicians play an important role in managing the issues of people with epilepsy.

Control rod drives

International Nuclear Information System (INIS)

Hayakawa, Hiroyasu.

1979-01-01

Purpose: To enable rapid control in a simple circuit by providing a motor control device having an electric capacity capable of simultaneously driving all of the control rods rapidly only in the inserting direction as well as a motor controlling device capable of fine control for the insertion and extraction at usual operation. Constitution: The control rod drives comprise a first motor control device capable of finely controlling the control rods both in inserting and extracting directions, a second motor control device capable of rapidly driving the control rods only in the inserting direction, and a first motor switching circuit and a second motor switching circuit switched by switches. Upon issue of a rapid insertion instruction for the control rods, the second motor switching circuit is closed by the switch and the second motor control circuit and driving motors are connected. Thus, each of the control rod driving motors is driven at a high speed in the inserting direction to rapidly insert all of the control rods. (Yoshino, Y.)

Validation and Application of Computed Radiography (CR) Tangential Technique for Wall Thickness Measurement of 10 Inch Carbon Steel Pipe

International Nuclear Information System (INIS)

Norhazleena Azaman; Khairul Anuar Mohd Salleh; Amry Amin Abas; Arshad Yassin; Sukhri Ahmad

2016-01-01

Oil and gas industry requires Non Destructive Testing (NDT) to ensure each components, in-service and critical, are fit-for-purpose. Pipes that are used to transfer oil or gas are amongst the critical component that needs to be well maintained and inspected. Typical pipe discontinuities that may lead to unintended incidents are erosion, corrosion, dent, welding defects, etc. Wall thickness assessment, with Radiography Testing (RT) is normally used to inspect such discontinuities and can be performed with two approaches; (a) center line beam tangential technique (b) offset from the centre pipe tangential technique. The latter is a method of choice for this work because of the pipe dimension and limited radiation safe distance at site. Two successful validation approaches (simulation and experimental) were performed to determine the probability of successfulness before the actual RT work with tangential technique is carried out. The pipe was a 10 inch diameter in-service wrapped carbon steel. A 9 Ci Ir-192 and white Imaging Plate (IP) were used as a gamma radiation source and to record the radiographic image. Result of this work suggest that RT with tangential technique for 10 inch wrapped in-service carbon steel pipe can be successfully performed. (author)

Development of the RANCOR Rotary-Percussive Coring System for Mars Sample Return

Science.gov (United States)

Paulsen, Gale; Indyk, Stephen; Zacny, Kris

2014-01-01

A RANCOR drill was designed to fit a Mars Exploration Rover (MER) class vehicle. The low mass of 3 kg was achieved by using the same actuator for three functions: rotation, percussions, and core break-off. Initial testing of the drill exposed an unexpected behavior of an off-the-shelf sprag clutch used to couple and decouple rotary-percussive function from the core break off function. Failure of the sprag was due to the vibration induced during percussive drilling. The sprag clutch would back drive in conditions where it was expected to hold position. Although this did not affect the performance of the drill, it nevertheless reduced the quality of the cores produced. Ultimately, the sprag clutch was replaced with a custom ratchet system that allowed for some angular displacement without advancing in either direction. Replacing the sprag with the ratchet improved the collected core quality. Also, premature failure of a 300-series stainless steel percussion spring was observed. The 300-series percussion spring was ultimately replaced with a music wire spring based on performances of previously designed rotary-percussive drill systems.

Evaluation of new 5 inch photomultiplier for use in threshold Cherenkov detectors with aerogel radiator

International Nuclear Information System (INIS)

Wojtsekhowski, B.; Zorn, C.; Flyckt, S.O.

2000-01-01

A cost effective alternative to UV-sensitive 5 inch PMTs often used with threshold Aerogel Cherenkov detectors has been developed and tested. The photomultiplier -XP4572-is a variation of the Photonis XP4512 glass window tube with improved electron collection efficiency. Fast timing and high gain were only moderately compromised. The effective quantum efficiency has been measured as twice that of a Burle 8854 Quantacon when exposed to a Cherenkov spectrum generated by Ru-106 electrons (les;3.54 MeV) through 1 cm of high index, high transparency Matsushita Electric aerogel (n=1.05). This new phototube is being installed in an aerogel-based Cherenkov detector for Hall A at Jefferson Lab

Control rod drive

International Nuclear Information System (INIS)

Hawke, B.C.

1986-01-01

A reactor core, one or more control rods, and a control rod drive are described for selectively inserting and withdrawing the one or more control rods into and from the reactor core, which consists of: a support structure secured beneath the reactor core; control rod positioning means supported by the support structure for movably supporting the control rod for movement between a lower position wherein the control rod is located substantially beneath the reactor core and an upper position wherein at least an upper portion of the control rod extends into the reactor core; transmission means; primary drive means connected with the control rod positioning means by the transmission means for positioning the control rod under normal operating conditions; emergency drive means for moving the control rod from the lower position to the upper position under emergency conditions, the emergency drive means including a weight movable between an upper and a lower position, means for movably supporting the weight, and means for transmitting gravitational force exerted on the weight to the control rod positioning means to move the control rod upwardly when the weight is pulled downwardly by gravity; the transmission means connecting the control rod positioning means with the emergency drive means so that the primary drive means effects movement of the weight and the control rod in opposite directions under normal conditions, thus providing counterbalancing to reduce the force required for upward movement of the control rod under normal conditions; and restraint means for restraining the fall of the weight under normal operating conditions and disengaging the primary drive means to release the weight under emergency conditions

Noninductive current drive in tokamaks

International Nuclear Information System (INIS)

Uckan, N.A.

1985-01-01

Various current drive mechanisms may be grouped into four classes: (1) injection of energetic particle beams; (2) launching of rf waves; (3) hybrid schemes, which are combinations of various rf schemes (rf plus beams, rf and/or beam plus ohmic heating, etc.); and (4) other schemes, some of which are specific to reactor plasma conditions requiring the presence of alpha particle or intense synchrotron radiation. Particle injection schemes include current drive by neutral beams and relativistic electron beams. The rf schemes include current drive by the lower hybrid (LH) waves, the electron waves, the waves in the ion cyclotron range of frequencies, etc. Only a few of these approaches, however, have been tested experimentally, with the broadest data base available for LH waves. Included in this report are (1) efficiency criteria for current drive, (2) current drive by neutral beam injection, (3) LH current drive, (4) electron cyclotron current drive, (5) current drive by ion cyclotron waves - minority species heating, and (6) current drive by other schemes (such as hybrids and low frequency waves)

Teen Driving Risk and Prevention: Naturalistic Driving Research Contributions and Challenges

OpenAIRE

Simons-Morton, Bruce G.; Ehsani, Johnathon P.; Gershon, Pnina; Klauer, Sheila G.; Dingus, Thomas A.

2017-01-01

Naturalistic driving (ND) methods may be particularly useful for research on young driver crash risk. Novices are not safe drivers initially, but tend to improve rapidly, although the pace of learning is highly variable. However, knowledge is lacking about how best to reduce the learning curve and the variability in the development of safe driving judgment. A great deal has been learned from recent naturalistic driving (ND) studies that have included young drivers, providing objective informa...

Modeling Driving Performance Using In-Vehicle Speech Data From a Naturalistic Driving Study.

Science.gov (United States)

Kuo, Jonny; Charlton, Judith L; Koppel, Sjaan; Rudin-Brown, Christina M; Cross, Suzanne

2016-09-01

We aimed to (a) describe the development and application of an automated approach for processing in-vehicle speech data from a naturalistic driving study (NDS), (b) examine the influence of child passenger presence on driving performance, and (c) model this relationship using in-vehicle speech data. Parent drivers frequently engage in child-related secondary behaviors, but the impact on driving performance is unknown. Applying automated speech-processing techniques to NDS audio data would facilitate the analysis of in-vehicle driver-child interactions and their influence on driving performance. Speech activity detection and speaker diarization algorithms were applied to audio data from a Melbourne-based NDS involving 42 families. Multilevel models were developed to evaluate the effect of speech activity and the presence of child passengers on driving performance. Speech activity was significantly associated with velocity and steering angle variability. Child passenger presence alone was not associated with changes in driving performance. However, speech activity in the presence of two child passengers was associated with the most variability in driving performance. The effects of in-vehicle speech on driving performance in the presence of child passengers appear to be heterogeneous, and multiple factors may need to be considered in evaluating their impact. This goal can potentially be achieved within large-scale NDS through the automated processing of observational data, including speech. Speech-processing algorithms enable new perspectives on driving performance to be gained from existing NDS data, and variables that were once labor-intensive to process can be readily utilized in future research. © 2016, Human Factors and Ergonomics Society.

Dementia and driving

Science.gov (United States)

... this page: //medlineplus.gov/ency/patientinstructions/000028.htm Dementia and driving To use the sharing features on ... please enable JavaScript. If your loved one has dementia , deciding when they can no longer drive may ...

Driving After a Stroke

Science.gov (United States)

... 23,2015 Can I drive after a stroke? Driving is often a major concern after someone has a stroke. It’s not unusual for stroke survivors to want to drive. Being able to get around after a stroke is important. Safety behind the wheel is even more important after ...

THE IMPACT OF TEXT DRIVING ON DRIVING SAFETY

OpenAIRE

Sanaz Motamedi; Jyh-Hone Wang

2016-01-01

In an increasingly mobile era, the wide availability of technology for texting and the prevalence of hands-free form have introduced a new safety concern for drivers. To assess this concern, a questionnaire was first deployed online to gain an understanding of drivers’ text driving experiences as well as their demographic information. The results from 232 people revealed that the majority of drivers are aware of the associated risks with texting while driving. However, more than one-fourth of...

i3Drive, a 3D interactive driving simulator.

Science.gov (United States)

Ambroz, Miha; Prebil, Ivan

2010-01-01

i3Drive, a wheeled-vehicle simulator, can accurately simulate vehicles of various configurations with up to eight wheels in real time on a desktop PC. It presents the vehicle dynamics as an interactive animation in a virtual 3D environment. The application is fully GUI-controlled, giving users an easy overview of the simulation parameters and letting them adjust those parameters interactively. It models all relevant vehicle systems, including the mechanical models of the suspension, power train, and braking and steering systems. The simulation results generally correspond well with actual measurements, making the system useful for studying vehicle performance in various driving scenarios. i3Drive is thus a worthy complement to other, more complex tools for vehicle-dynamics simulation and analysis.

Development of a Surface Micromachined On-Chip Flat Disk Micropump

Directory of Open Access Journals (Sweden)

M. I. KILANI

2009-08-01

Full Text Available The paper presents research progress in the development of a surface micromachined flat disk micropump which employs the viscous and centrifugal effects acting on a layer of fluid sandwiched between a rotating flat disk and a stationary plate. The pump is fabricated monolithically on-chip using Sandia’s Ultraplanar Multilevel MEMS Technology (SUMMiT™ where an electrostatic comb-drive Torsional Ratcheting Actuator (TRA drives the flat disk through a geared transmission. The paper reviews available analytical models for flow geometries similar to that of the described pump, and presents a set of experiments which depict its performance and possible failure modes. Those experiments highlight future research directions in the development of electrostatically-actuated, CMOS-compatible, surface micromachined pumps.

A drive through Web 2.0: an exploration of driving safety promotion on Facebook™.

Science.gov (United States)

Apatu, Emma J I; Alperin, Melissa; Miner, Kathleen R; Wiljer, David

2013-01-01

This study explored Facebook™ to capture the prevalence of driving safety promotion user groups, obtain user demographic information, to understand if Facebook™ user groups influence reported driving behaviors, and to gather a sense of perceived effectiveness of Facebook™ for driving safety promotion targeted to young adults. In total, 96 driving safety Facebook™ groups (DSFGs) were identified with a total of 33,368 members, 168 administrators, 156 officers, 1,598 wall posts representing 12 countries. A total of 85 individuals participated in the survey. Demographic findings of this study suggest that driving safety promotion can be targeted to young and older adults. Respondents' ages ranged from 18 to 66 years. A total of 62% of respondents aged ≤ 24 years and 57.8% of respondents aged ≥ 25 years reported changing their driving-related behaviors as a result of reading information on the DSFGs to which they belonged. A higher proportion of respondents ≥ 25 years were significantly more likely to report Facebook™ and YouTube™ as an effective technology for driving safety promotion. This preliminary study indicates that DSFGs may be effective tools for driving safety promotion among young adults. More research is needed to understand the cognition of Facebook™ users as it relates to adopting safe driving behavior. The findings from this study present descriptive data to guide public health practitioners for future health promotion activities on Facebook™.

Self-driving carsickness.

Science.gov (United States)

Diels, Cyriel; Bos, Jelte E

2016-03-01

This paper discusses the predicted increase in the occurrence and severity of motion sickness in self-driving cars. Self-driving cars have the potential to lead to significant benefits. From the driver's perspective, the direct benefits of this technology are considered increased comfort and productivity. However, we here show that the envisaged scenarios all lead to an increased risk of motion sickness. As such, the benefits this technology is assumed to bring may not be capitalised on, in particular by those already susceptible to motion sickness. This can negatively affect user acceptance and uptake and, in turn, limit the potential socioeconomic benefits that this emerging technology may provide. Following a discussion on the causes of motion sickness in the context of self-driving cars, we present guidelines to steer the design and development of automated vehicle technologies. The aim is to limit or avoid the impact of motion sickness and ultimately promote the uptake of self-driving cars. Attention is also given to less well known consequences of motion sickness, in particular negative aftereffects such as postural instability, and detrimental effects on task performance and how this may impact the use and design of self-driving cars. We conclude that basic perceptual mechanisms need to be considered in the design process whereby self-driving cars cannot simply be thought of as living rooms, offices, or entertainment venues on wheels. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Predicting psychopharmacological drug effects on actual driving performance (SDLP) from psychometric tests measuring driving-related skills

OpenAIRE

Verster, Joris C.; Roth, Thomas

2011-01-01

Rationale There are various methods to examine driving ability. Comparisons between these methods and their relationship with actual on-road driving is often not determined. Objective The objective of this study was to determine whether laboratory tests measuring driving-related skills could adequately predict on-the-road driving performance during normal traffic. Methods Ninety-six healthy volunteers performed a standardized on-the-road driving test. Subjects were instructed to drive with a ...

Sequential Dependencies in Driving

Science.gov (United States)

Doshi, Anup; Tran, Cuong; Wilder, Matthew H.; Mozer, Michael C.; Trivedi, Mohan M.

2012-01-01

The effect of recent experience on current behavior has been studied extensively in simple laboratory tasks. We explore the nature of sequential effects in the more naturalistic setting of automobile driving. Driving is a safety-critical task in which delayed response times may have severe consequences. Using a realistic driving simulator, we find…

Driving automation forward : human factors for limited-ability autonomous driving systems.

Science.gov (United States)

2010-01-01

Over the past 100 years, there has been a : steady progression of innovations that : enhance the driving experience, in particular : the continuing trend toward automating more : driving tasks. Human Factors for Limited-Ability : Autonomous Drivin...

Linear step drive

International Nuclear Information System (INIS)

Haniger, L.; Elger, R.; Kocandrle, L.; Zdebor, J.

1986-01-01

A linear step drive is described developed in Czechoslovak-Soviet cooperation and intended for driving WWER-1000 control rods. The functional principle is explained of the motor and the mechanical and electrical parts of the drive, power control, and the indicator of position are described. The motor has latches situated in the reactor at a distance of 3 m from magnetic armatures, it has a low structural height above the reactor cover, which suggests its suitability for seismic localities. Its magnetic circuits use counterpoles; the mechanical shocks at the completion of each step are damped using special design features. The position indicator is of a special design and evaluates motor position within ±1% of total travel. A drive diagram and the flow chart of both the control electronics and the position indicator are presented. (author) 4 figs

Hurried driving: Relationship to distress tolerance, driver anger, aggressive and risky driving in college students.

Science.gov (United States)

Beck, Kenneth H; Daughters, Stacey B; Ali, Bina

2013-03-01

Being a hurried driver is associated with a variety of risky driving behaviors, yet the mechanisms underlying this behavior remain unknown. Distress tolerance, defined as an individual's capability to experience and endure negative emotional states, was examined as a predictor of hurried driving among 769 college students. Results indicate that after controlling for age, gender, race, ethnicity, the student's year in school, their grade point average, driving frequency, angry driving, aggressive driving as well as other forms of self-reported risky driving; hurried driving was significantly associated with lower levels of distress tolerance. Hurried drivers also reported greater levels of frustration and impatience with other drivers, suggesting that they have difficulty in withstanding or coping with negative psychological states when driving. Traditional traffic safety campaigns that emphasize enforcement may be less successful with these drivers. The need to develop campaigns that address the affective coping abilities that contribute to this behavioral pattern is discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Driving performance at lateral system limits during partially automated driving.

Science.gov (United States)

Naujoks, Frederik; Purucker, Christian; Wiedemann, Katharina; Neukum, Alexandra; Wolter, Stefan; Steiger, Reid

2017-11-01

This study investigated driver performance during system limits of partially automated driving. Using a motion-based driving simulator, drivers encountered different situations in which a partially automated vehicle could no longer safely keep the lateral guidance. Drivers were distracted by a non-driving related task on a touch display or driving without an additional secondary task. While driving in partially automated mode drivers could either take their hands off the steering wheel for only a short period of time (10s, so-called 'Hands-on' variant) or for an extended period of time (120s, so-called 'Hands-off' variant). When the system limit was reached (e.g., when entering a work zone with temporary lines), the lateral vehicle control by the automation was suddenly discontinued and a take-over request was issued to the drivers. Regardless of the hands-off interval and the availability of a secondary task, all drivers managed the transition to manual driving safely. No lane exceedances were observed and the situations were rated as 'harmless' by the drivers. The lack of difference between the hands-off intervals can be partly attributed to the fact that most of the drivers kept contact to the steering wheel, even in the hands-off condition. Although all drivers were able to control the system limits, most of them could not explain why exactly the take-over request was issued. The average helpfulness of the take-over request was rated on an intermediate level. Consequently, providing drivers with information about the reason for a system limit can be recommended. Copyright © 2017 Elsevier Ltd. All rights reserved.

High-power converters and AC drives

CERN Document Server

Wu, Bin

2017-01-01

This new edition reflects the recent technological advancements in the MV drive industry, such as advanced multilevel converters and drive configurations. It includes three new chapters, Control of Synchronous Motor Drives, Transformerless MV Drives, and Matrix Converter Fed Drives. In addition, there are extensively revised chapters on Multilevel Voltage Source Inverters and Voltage Source Inverter-Fed Drives. This book includes a systematic analysis on a variety of high-power multilevel converters, illustrates important concepts with simulations and experiments, introduces various megawatt drives produced by world leading drive manufacturers, and addresses practical problems and their mitigations methods.

Driving pleasure and perceptions of the transition from no automation to full self-driving automation

DEFF Research Database (Denmark)

Bjørner, Thomas

2018-01-01

In this article, I offer a sociological user perspective on increased self-driving automation, which has evolved from a long history associated with automobility. This study explores complex, perceived a priori driving pleasures in different scenarios involving self-driving cars. The methods used...... consisted of 32 in-depth interviews with participants who were given eight video examples (two video examples within four different scenarios) to watch. A numerical rating scales formed parts of the interviews. The findings revealed that driving pleasure when using increasingly automated driving...... technologies is very complex and must be seen within various contexts, including, for example, different speeds, road conditions, purposes, driving distances, and numbers of people in the car. Self-driving cars are not just about technology, increased safety, and better traffic flow, but are also dependent...

A Difficult Journey: Reflections on Driving and Driving Cessation From a Team of Clinical Researchers.

Science.gov (United States)

Liddle, Jacki; Gustafsson, Louise; Mitchell, Geoffrey; Pachana, Nancy A

2017-02-01

Recognizing the clinical importance and safety and well-being implications for the population, a multidisciplinary team has been researching older drivers and driving cessation issues for more than 15 years. Using empirical approaches, the team has explored quality of life and participation outcomes related to driving and nondriving for older people and has developed interventions to improve outcomes after driving cessation. The team members represent occupational therapists, medical practitioners, and clinical and neuropsychologists. While building the evidence base for driving- and driving cessation-related clinical practice, the researchers have also had first-hand experiences of interruptions to their own or parents' driving; involvement of older family members in road crashes; and provision of support during family members' driving assessment and cessation. This has led to reflection on their understandings and re-evaluation and refocusing of their perspectives in driving cessation research. This work will share the narratives of the authors and note their developing perspectives and foci within research as well as their clinical practice. Personal reflections have indicated the far-reaching implications for older drivers and family members of involvement in road crashes: the potential for interruptions to driving as a time for support and future planning and the conflicting and difficult roles of family members within the driving cessation process. Overall the lived, personal experience of the authors has reinforced the complex nature of driving and changes to driving status for the driver and their support team and the need for further research and support. © The Author 2016. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The ratchet–shakedown diagram for a thin pressurised pipe subject to additional axial load and cyclic secondary global bending

International Nuclear Information System (INIS)

Bradford, R.A.W.; Tipping, D.J.

2015-01-01

The ratchet and shakedown boundaries are derived analytically for a thin cylinder composed of elastic-perfectly plastic Tresca material subject to constant internal pressure with capped ends, plus an additional constant axial load, F, and a cycling secondary global bending load. The analytic solution is in good agreement with solutions found using the linear matching method. When F is tensile, ratcheting can occur for sufficiently large cyclic bending loads in which the pipe gets longer and thinner but its diameter remains the same. When F is compressive, ratcheting can occur in which the pipe diameter increases and the pipe gets shorter, but its wall thickness remains the same. When subject to internal pressure and cyclic bending alone (F = 0), no ratcheting is possible, even for arbitrarily large bending loads, despite the presence of the axial pressure load. The reason is that the case with a primary axial membrane stress exactly equal to half the primary hoop membrane stress is equipoised between tensile and compressive axial ratcheting, and hence does not ratchet at all. This remarkable result appears to have escaped previous attention. - Highlights: • A thin cylinder is subject to pressure and cyclic global bending and additional axial load. • Ratchet and shakedown boundaries are derived analytically and using LMM. • Good agreement is found. • No ratcheting occurs for zero additional axial load.

Efficient Driving of Piezoelectric Transducers Using a Biaxial Driving Technique.

Directory of Open Access Journals (Sweden)

Samuel Pichardo

Full Text Available Efficient driving of piezoelectric materials is desirable when operating transducers for biomedical applications such as high intensity focused ultrasound (HIFU or ultrasound imaging. More efficient operation reduces the electric power required to produce the desired bioeffect or contrast. Our preliminary work [Cole et al. Journal of Physics: Condensed Matter. 2014;26(13:135901.] suggested that driving transducers by applying orthogonal electric fields can significantly reduce the coercivity that opposes ferroelectric switching. We present here the experimental validation of this biaxial driving technique using piezoelectric ceramics typically used in HIFU. A set of narrow-band transducers was fabricated with two sets of electrodes placed in an orthogonal configuration (following the propagation and the lateral mode. The geometry of the ceramic was chosen to have a resonance frequency similar for the propagation and the lateral mode. The average (± s.d. resonance frequency of the samples was 465.1 (± 1.5 kHz. Experiments were conducted in which each pair of electrodes was driven independently and measurements of effective acoustic power were obtained using the radiation force method. The efficiency (acoustic/electric power of the biaxial driving method was compared to the results obtained when driving the ceramic using electrodes placed only in the pole direction. Our results indicate that the biaxial method increases efficiency from 50% to 125% relative to the using a single electric field.

H1 antihistamines and driving.

Science.gov (United States)

Popescu, Florin Dan

2008-01-01

Driving performances depend on cognitive, psychomotor and perception functions. The CNS adverse effects of some H1 antihistamines can alter the patient ability to drive. Data from studies using standardized objective cognitive and psychomotor tests (Choice Reaction Time, Critical Flicker Fusion. Digital Symbol Substitution Test), functional brain imaging (Positron Emission Tomography, functional Magnetic Resonance Imaging), neurophysiological studies (Multiple Sleep Latency Test, auditory and visual evoked potentials), experimental simulated driving (driving simulators) and real driving studies (the Highway Driving Test, with the evaluation of the Standard Deviation Lateral Position, and the Car Following Test, with the measurement of the Brake Reaction Time) must be discussed in order to classify a H1 antihistamine as a true non-sedating one.

Smartphone Based Approach For Monitoring Inefficient And Unsafe Driving Behavior And Recognizing Drink And Drive Conditions.

Directory of Open Access Journals (Sweden)

G. V. Mane

2015-08-01

Full Text Available Many automobile drivers having knowledge of the driving behaviours and habits that can lead to inefficient and unsafe driving. However it is often the case that these same drivers unknowingly manifest these inefficient and unsafe driving behaviours in their everyday driving activity. The proposed system proposes a practical and economical way to capture measure and alert drives of inefficient and unsafe driving as well as highly efficient system aimed at early detection and alert of dangerous vehicle maneuvers typically related to drunk driving. The upcoming solution consists of a mobile application running on a modern smartphone device paired with a compatible OBDII On-board diagnostics II reader.

Driving Competence in Mild Dementia with Lewy Bodies: In Search of Cognitive Predictors Using Driving Simulation

Directory of Open Access Journals (Sweden)

Stephanie Yamin

2015-01-01

Full Text Available Driving is a multifactorial behaviour drawing on multiple cognitive, sensory, and physical systems. Dementia is a progressive and degenerative neurological condition that impacts the cognitive processes necessary for safe driving. While a number of studies have examined driving among individuals with Alzheimer’s disease, less is known about the impact of Dementia with Lewy Bodies (DLB on driving safety. The present study compared simulated driving performance of 15 older drivers with mild DLB with that of 21 neurologically healthy control drivers. DLB drivers showed poorer performance on all indicators of simulated driving including an increased number of collisions in the simulator and poorer composite indicators of overall driving performance. A measure of global cognitive function (i.e., the Mini Mental State Exam was found to be related to the overall driving performance. In addition, measures of attention (i.e., Useful Field of View, UFOV and space processing (Visual Object and Space Perception, VOSP, Test correlated significantly with a rater’s assessment of driving performance.

Drive transmission system between a driving organ and a receiver organ

International Nuclear Information System (INIS)

Guillot, J.F.

1985-01-01

The present invention applies to the control rods of a water cooled nuclear reactor. The drive transmission system is disposed on the internal kinematic chain, between the control rod which is the receiver organ, and the driving organ. The control rod translation is obtained from a motion of rotation transformed in a motion of translation by means of a screw-nut system. The present invention prevents from control rod ejection in case of depressurization of the vessel containing the control rod drives or in case of reactor upsetting when it is embarked [fr

Driving things

DEFF Research Database (Denmark)

Nevile, Maurice Richard

2015-01-01

I explore how participants organise involvement with objects brought into the car, relative to the demands of driving and social activity. Objects in cars commonly include phones or other technologies, food, body care products, texts, clothing, bags and carry items, toys, and even animals...... 2004, Haddington et al. 2012). I focus here especially on how the practical and interactional work of locating, seeing, placing, handling, hearing, and relinquishing, is ordered and accomplished relative to the emerging and contingent demands of both driving and social participation......, such that involvement with objects is constituted as secondary to driving in a multiactivity setting (e.g. Haddington et al. 2014). We see how events with, for, of, and even by objects can occur as predictable, planned and even designed for (e.g. changing glasses, applying body lotion), or might be unexpected...

Recent developments in high charge state heavy ion beams at the LBL 88-inch Cyclotron

International Nuclear Information System (INIS)

Gough, R.A.; Clark, D.J.; Glasgow, L.R.

1978-01-01

Recent advances in design and operation of the internal PIG sources at the LBL 88-Inch Cyclotron have led to the development of high charge state (0.4 16 O 8+ . Total external intensities of these beams range from 10 12 particles/s for 6 Li 3+ to 0.1 particles/s for 16 O 8+ . Techniques have been developed for routine tune-out of the low intensity beams. These include use of model beams and reliance on the large systematic data base of cyclotron parameters which has been developed over many years of operation. Techniques for delivery of these weak beams to the experimental target areas are presented. Source design and operation, including special problems associated with Li, Be, and B beams are discussed

The impact of therapeutic opioid agonists on driving-related psychomotor skills assessed by a driving simulator or an on-road driving task: A systematic review.

Science.gov (United States)

Ferreira, Diana H; Boland, Jason W; Phillips, Jane L; Lam, Lawrence; Currow, David C

2018-04-01

Driving cessation is associated with poor health-related outcomes. People with chronic diseases are often prescribed long-term opioid agonists that have the potential to impair driving. Studies evaluating the impact of opioids on driving-related psychomotor skills report contradictory results likely due to heterogeneous designs, assessment tools and study populations. A better understanding of the effects of regular therapeutic opioid agonists on driving can help to inform the balance between individual's independence and community safety. To identify the literature assessing the impact of regular therapeutic opioid agonists on driving-related psychomotor skills for people with chronic pain or chronic breathlessness. Systematic review reported in accordance with the Preferred Reporting Items for Systematic Review and Meta-analysis statement; PROSPERO Registration CRD42017055909. Six electronic databases and grey literature were systematically searched up to January, 2017. Inclusion criteria were as follows: (1) empirical studies reporting data on driving simulation, on-the-road driving tasks or driving outcomes; (2) people with chronic pain or chronic breathlessness; and (3) taking regular therapeutic opioid agonists. Critical appraisal used the National Institutes of Health's quality assessment tools. From 3809 records screened, three studies matched the inclusion criteria. All reported data on people with chronic non-malignant pain. No significant impact of regular therapeutic opioid agonists on people's driving-related psychomotor skills was reported. One study reported more intense pain significantly worsened driving performance. This systematic review does not identify impaired simulated driving performance when people take regular therapeutic opioid agonists for symptom control, although more prospective studies are needed.

Effect of consecutive driving on accident risk: a comparison between passenger and freight train driving.

Science.gov (United States)

Chang, Hsin-Li; Ju, Lai-Shun

2008-11-01

This study combined driver-responsible accidents with on-board driving hours to examine the effect of consecutive driving on the accident risk of train operations. The data collected from the Taiwan Railway Administration for the period 1996-2006 was used to compute accident rates for varied accumulated driving hours for passenger and freight trains. The results showed that accident risk grew with increased consecutive driving hours for both passenger and freight trains, and doubled that of the first hour after four consecutive hours of driving. Additional accident risk was found for freight trains during the first hour due to required shunting in the marshalling yards where there are complex track layouts and semi-automatic traffic controls. Also, accident risk for train driving increased more quickly over consecutive driving hours than for automobile driving, and accumulated fatigue caused by high working pressure and monotony of the working environment are considered to be the part of the reason. To prevent human errors accidents, enhancing safety equipment, driver training programs, and establishing a sound auditing system are suggested and discussed.

Self-driving carsickness

NARCIS (Netherlands)

Diels, C.; Bos, J.E.

2016-01-01

This paper discusses the predicted increase in the occurrence and severity of motion sickness in self-driving cars. Self-driving cars have the potential to lead to significant benefits. From the driver's perspective, the direct benefits of this technology are considered increased comfort and

Self-driving carsickness.

NARCIS (Netherlands)

Diels, C.; Bos, J.E.

2016-01-01

This paper discusses the predicted increase in the occurrence and severity of motion sickness in self-driving cars. Self-driving cars have the potential to lead to significant benefits. From the driver's perspective, the direct benefits of this technology are considered increased comfort and

Antihistamines and driving safety.

Science.gov (United States)

O'Hanlon, J F

1988-10-27

The results of two placebo-controlled driving performance studies confirm laboratory data showing that the nonsedating antihistamine terfenadine does not influence the driving performance of users. The amplitude of vehicle weaving calculated for drivers who received this agent did not differ from control values. Neither terfenadine nor loratadine, another nonsedating antihistamine, potentiated the adverse effects of alcohol on driving performance.

Vortex dynamics in two-dimensional Josephson junction arrays with asymmetrically bimodulated potential

International Nuclear Information System (INIS)

Nie, Qing-Miao; Zhang, Sha-Sha; Chen, Qing-Hu; Zhou, Wei

2012-01-01

On the basis of resistively-shunted junction dynamics, we study vortex dynamics in two-dimensional Josephson junction arrays with asymmetrically single and bimodulated periodic pinning potential for the full range of vortex density f. The ratchet effect occurring at a certain range of temperature, current, and f, is observed in our simulation. We explain the microscopic behavior behind this effect by analyzing the vortex distribution and interaction. The reversal of the ratchet effect can be observed at several f values for a small driven current. This effect is stronger when the asymmetric potential is simultaneously introduced in two directions. -- Highlights: ► The ratchet effect in Josephson junction arrays strongly depends on vortex density. ► The reversed ratchet effect can be observed at several f for a small current. ► The interaction between vortices can explain the reversed ratchet effect. ► The ratchet effect is enhanced by injecting the bimodulated asymmetric potential.

Wrong-way driving.

NARCIS (Netherlands)

2006-01-01

Wrong-way driving is a phenomenon that mainly happens on motorways. Although the number of wrong-way crashes is relatively limited, their consequences are much more severe than the consequences of other motorway injury crashes. The groups most often causing wrong-way driving accidents are young,

Older Drivers' Reasons for Reducing the Overall Amount of Their Driving and for Avoiding Selected Driving Situations

DEFF Research Database (Denmark)

Meng, Annette; Siren, Anu Kristiina

2015-01-01

that the reduction in driving and avoidance of driving situations are separate types of self-regulatory behavior; that self-regulation of driving is an automatic process, in which older drivers are not aware that they are compensating for functional loss; and that it is important to acknowledge gender differences......Structured telephone interviews were conducted with 840 older drivers to explore their reasons for self-regulating their driving. The main reason for reduced driving was having fewer activities to drive to, and for avoidance of driving situations, reasons also included not liking or feeling...

Automobile driving in older adults: factors affecting driving restriction in men and women.

Science.gov (United States)

Marie Dit Asse, Laetitia; Fabrigoule, Colette; Helmer, Catherine; Laumon, Bernard; Lafont, Sylviane

2014-11-01

To identify factors associated with driving restriction in elderly men and women. Prospective cohort study of French drivers from 2003 to 2009. The Three-City Cohort of Bordeaux, a prospective study of 2,104 people aged 65 and older. Five hundred twenty-three drivers with a mean age of 76 (273 male, 250 female). Sociodemographic characteristics, driving habits, health variables, cognitive evaluation and dementia diagnosis. Predementia was defined as no dementia at one follow-up and dementia at the next follow-up. Over the 6-year period, 54% of men and 63% of women stopped driving or reduced the distance they drove. Predementia, Parkinson's disease, older age, and a high number of kilometers previously driven were common restriction factors in both sexes. Prevalent dementia, depressive symptomatology, a decline in one or more instrumental activities of daily living, and poor visual working memory were specific factors in men. In women, low income, fear of falling, slow processing speed, and severe decline in global cognitive performance all affected driving restriction. Older women restricted their driving activity more than older men, regardless of the number of kilometers previously driven, physical health, and cognitive status. Factors affecting driving restriction differed according to sex, and women were more likely to stop driving than men in the period preceding a dementia diagnosis. © 2014, Copyright the Authors Journal compilation © 2014, The American Geriatrics Society.

Refurbishment and modification of existing protective shipping packages (for 30-inch UF{sub 6} cylinders) per USDOT specification No. USA-DOT-21PF-1A

Energy Technology Data Exchange (ETDEWEB)

Housholder, W.R. [Nuclear Containers, Incorporated, Elizabethton, TN (United States)

1991-12-31

This paper addresses the refurbishment procedures for existing shipping containers for 30-inch diameter UF{sub 6} cylinders in accordance with DOT Specification 21PF-1 and the criteria used to determine rejection when such packages are unsuitable for refurbishment.

On use of radial evanescence remain term in kinematic hardening

International Nuclear Information System (INIS)

Geyer, P.

1995-01-01

This paper presents the interest which lies in non-linear kinematic hardening rule with radial evanescence remain term as proposed for modelling multiaxial ratchetting. From analytical calculations in the case of the tension/torsion test, this ratchetting is compared with that proposed by Armstrong and Frederick. A modification is then proposed for Chaboche's elastoplastic model with two non-linear kinematic variables, by coupling the two types of hardening by means of two scalar parameters. Identification of these two parameters returns to speculate on the directions of strain in order to adjust the ratchetting to experimental observations. Using biaxial ratchetting tests on stainless steel 316 L specimens at ambient temperature, it is shown that satisfactory modelling of multiaxial ratchetting is obtained. (author). 4 refs., 5 figs

Driving with the wandering mind: the effect that mind-wandering has on driving performance.

Science.gov (United States)

Yanko, Matthew R; Spalek, Thomas M

2014-03-01

The principal objective of the present work was to examine the effects of mind state (mind-wandering vs. on-task) on driving performance in a high-fidelity driving simulator. Mind-wandering is thought to interfere with goal-directed thought. It is likely, then, that when driving, mind-wandering might lead to impairments in critical aspects of driving performance. In two experiments, we assess the extent to which mind-wandering interferes with responsiveness to sudden events, mean velocity, and headway distance. Using a car-following procedure in a high-fidelity driving simulator, participants were probed at random times to indicate whether they were on-task at that moment or mind-wandering. The dependent measures were analyzed based on the participant's response to the probe. Compared to when on-task, when mind-wandering participants showed longer response times to sudden events, drove at a higher velocity, and maintained a shorter headway distance. Collectively, these findings indicate that mind-wandering affects a broad range of driving responses and may therefore lead to higher crash risk. The results suggest that situations that are likely associated with mind-wandering (e.g., route familiarity) can impair driving performance.

Harmonic Coupling Analysis of a Multi-Drive System with Slim DC-link Drive

DEFF Research Database (Denmark)

Yang, Feng; Kwon, Jun Bum; Blaabjerg, Frede

2017-01-01

One of the problems with slim dc-link adjustable speed drive is the difficulties to analyze the harmonic coupling when it is integrated into a multi-drive system. The traditional methods analyze this harmonic issue by neglecting the harmonic coupling, and base on the linear time-invariant methods....... Its disadvantages include the time consumption and large computer memory. This paper proposes to do harmonic analysis by using the harmonic state-space modeling method by using the linear time-periodic theory. By using the proposed model, the harmonic couplings, between dc-link and point of common...... coupling in different drives, are all analyzed in the multi-drive system. In the meantime, the effects of the small film dc-link capacitance and the nonlinear characteristic of the diode rectifier are considered. The detailed modeling procedure, the simulations and the lab experiment on a two-drive system...

Method for driving an actuator, actuator drive, and apparatus comprising an actuator

OpenAIRE

2010-01-01

An actuator driver circuit includes a drive signal source and an electrical damping element having a negative resistance connected in series with the drive signal source. A controllable switch is provided for selectively switching the electrical damping element into or put of a signal path from a drive signal source output to a driver circuit output, in order to selectively change the electrical damping of an actuator. For example, the electrical damping of a radial actuator or a focus actuat...

Modeling Driving Behavior at Roundabouts: Impact of Roundabout Layout and Surrounding Traffic on Driving Behavior

OpenAIRE

Zhao, Min; Käthner, David; Söffker, Dirk; Jipp, Meike; Lemmer, Karsten

2017-01-01

Driving behavior prediction at roundabouts is an important challenge to improve driving safety by supporting drivers with intelligent assistance systems. To predict the driving behavior effciently steering wheel status was proven to have robust predictability based on a Support Vector Machine algorithm. Previous research has not considered potential effects of roundabout layout and surrounding traffic on driving behavior, but that consideration can certainly improve the prediction results....

Can We Study Autonomous Driving Comfort in Moving-Base Driving Simulators? A Validation Study.

Science.gov (United States)

Bellem, Hanna; Klüver, Malte; Schrauf, Michael; Schöner, Hans-Peter; Hecht, Heiko; Krems, Josef F

2017-05-01

To lay the basis of studying autonomous driving comfort using driving simulators, we assessed the behavioral validity of two moving-base simulator configurations by contrasting them with a test-track setting. With increasing level of automation, driving comfort becomes increasingly important. Simulators provide a safe environment to study perceived comfort in autonomous driving. To date, however, no studies were conducted in relation to comfort in autonomous driving to determine the extent to which results from simulator studies can be transferred to on-road driving conditions. Participants ( N = 72) experienced six differently parameterized lane-change and deceleration maneuvers and subsequently rated the comfort of each scenario. One group of participants experienced the maneuvers on a test-track setting, whereas two other groups experienced them in one of two moving-base simulator configurations. We could demonstrate relative and absolute validity for one of the two simulator configurations. Subsequent analyses revealed that the validity of the simulator highly depends on the parameterization of the motion system. Moving-base simulation can be a useful research tool to study driving comfort in autonomous vehicles. However, our results point at a preference for subunity scaling factors for both lateral and longitudinal motion cues, which might be explained by an underestimation of speed in virtual environments. In line with previous studies, we recommend lateral- and longitudinal-motion scaling factors of approximately 50% to 60% in order to obtain valid results for both active and passive driving tasks.

49 CFR 231.24 - Box and other house cars with roofs, 16 feet 10 inches or more above top of rail. 1

Science.gov (United States)

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Box and other house cars with roofs, 16 feet 10... APPLIANCE STANDARDS § 231.24 Box and other house cars with roofs, 16 feet 10 inches or more above top of.... Same as specified for “Box and Other House Cars.” (2) Dimensions. Same as specified for “Box and Other...

Driving styles among young novice drivers--the contribution of parental driving styles and personal characteristics.

Science.gov (United States)

Miller, Gila; Taubman-Ben-Ari, Orit

2010-03-01

As part of the effort to ascertain why young drivers are more at risk for car crashes, attention has recently turned to the effects of family, including the intergenerational transmission of driving styles from parents to offspring. The current study sought to further understanding of the nature and aspects of the family influence with the help of Bowen's family systems theory. In Phase 1 of the prospective study, 130 young driving students completed questionnaires tapping personal and personality measures, and their parents completed driving-related instruments. In Phase 2, a year after the young drivers had obtained their driver's license, they were administered the same questionnaires their parents had previously completed. The results show significant correlations between the parents' driving styles and those of their offspring a year after licensure. Furthermore, differentiation of self and self-efficacy in newly acquired driving skills were found to moderate or heighten the similarity between the driving styles of parents and their offspring. For young drivers reporting anxiety in Phase 1, this was associated with a reported anxious driving style a year later. Among young female drivers, anxiety was also associated with a reckless and careless style. Higher sensation seeking was related to higher reckless driving among young male drivers. The findings are discussed in the context of adolescence and the role of the study variables in the development and intergenerational transmission of driving styles. In addition to its theoretical contribution to the realms of intergenerational transmission in general, and young drivers in particular, the study may have practical implications for both family therapy and the design of driving interventions. Copyright 2009 Elsevier Ltd. All rights reserved.

Impaired-driving prevalence among US high school students: associations with substance use and risky driving behaviors.

Science.gov (United States)

Li, Kaigang; Simons-Morton, Bruce G; Hingson, Ralph

2013-11-01

We examined the prevalence of impaired driving among US high school students and associations with substance use and risky driving behavior. We assessed driving while alcohol or drug impaired (DWI) and riding with alcohol- or drug-impaired drivers (RWI) in a nationally representative sample of 11th-grade US high school students (n = 2431). We examined associations with drinking and binge drinking, illicit drug use, risky driving, and demographic factors using multivariate sequential logistic regression analysis. Thirteen percent of 11th-grade students reported DWI at least 1 of the past 30 days, and 24% reported RWI at least once in the past year. Risky driving was positively associated with DWI (odds ratio [OR] = 1.25; P phone calls (OR = 3.2) while driving. Our findings suggest the need for comprehensive approaches to the prevention of DWI, RWI, and other risky driving behavior.

Effects of chewing gum on driving performance as evaluated by the STISIM driving simulator.

Science.gov (United States)

Yoo, Ingyu; Kim, Eun-Joo; Lee, Joo-Hyun

2015-06-01

[Purpose] The purpose of this study was to determine the effects of chewing gum on driving performance in a driving simulator. [Subjects] In total, 26 young licensed drivers participated. [Methods] The driving scenario was typical of an urban environment: a single-carriageway, two-way road consisting of a mix of curved and straight sections, with considerable levels of traffic, pedestrians, and parked cars. Mean distance driven above the speed limit, lane position, mean distance driven across the center line, and mean distance driven off the road were used as estimates of brake, accelerator, and steering control. The results were compared with those of a non-chewing gum control condition. [Results] The driving performance while chewing gum was significantly better: the mean distance driven above the speed limit was 26.61% shorter, and the mean distance driven off the road was 31.99% shorter. Lane position and mean distance driven across the center line did not differ significantly between the two conditions. [Conclusion] Chewing gum appears to enhance driving performance during a sustained attention driving task.

HP 9816

CERN Multimedia

1982-01-01

The 9816 was introduced in late 1982. This was the low-cost model in the 200 Series range. It only had two expansion slots and featured a monitor integrated with the system unit and modular keyboard and mass storage (usually a 9121 dual 3.5 inch floppy drive). The monitor was nine inches diagonally with a 400 by 300 dot resolution. The HP 9816 was also designated as the HP 9000 216. It did not include any disk drives but it had a built-in 9 inch monochrome monitor, built-in HP-IB and RS-232 ports and 2 expansion slots. The standard keyboard for the 9816 is a itty-bitty number. The 9816 A came with 128K bytes of memory. The 9816 S included all of the above plus disk based BASIC and a card containing an additional 256K of memory bringing the total memory to 512K but only leaving only one expansion slot open.

Exploring Forensic Implications of the Fusion Drive

Directory of Open Access Journals (Sweden)

Shruti Gupta

2014-09-01

Full Text Available This paper explores the forensic implications of Apple's Fusion Drive. The Fusion Drive is an example of auto-tiered storage. It uses a combination of a flash drive and a magnetic drive. Data is moved between the drives automatically to maximize system performance. This is different from traditional caches because data is moved and not simply copied. The research included understanding the drive structure, populating the drive, and then accessing data in a controlled setting to observe data migration strategies. It was observed that all the data is first written to the flash drive with 4 GB of free space always maintained. If data on the magnetic drive is frequently accessed, it is promoted to the flash drive while demoting other information. Data is moved at a block-level and not a file-level. The Fusion Drive didn't alter the timestamps of files with data migration.

Electric Vehicle - Economical driving

DEFF Research Database (Denmark)

Jensen, VCE, Steen V.; Schøn, Henriette

1999-01-01

Instruct the reader in getting most satisfaction out of an EV, especially concerning driving and loading.......Instruct the reader in getting most satisfaction out of an EV, especially concerning driving and loading....

CLIC Drive Beam Phase Stabilisation

CERN Document Server

Gerbershagen, Alexander; Schulte, Daniel

The thesis presents phase stability studies for the Compact Linear Collider (CLIC) and focuses in particular on CLIC Drive Beam longitudinal phase stabilisation. This topic constitutes one of the main feasibility challenges for CLIC construction and is an essential component of the current CLIC stabilisation campaign. The studies are divided into two large interrelated sections: the simulation studies for the CLIC Drive Beam stability, and measurements, data analysis and simulations of the CLIC Test Facility (CTF3) Drive Beam phase errors. A dedicated software tool has been developed for a step-by-step analysis of the error propagation through the CLIC Drive Beam. It uses realistic RF potential and beam loading amplitude functions for the Drive and Main Beam accelerating structures, complete models of the recombination scheme and compressor chicane as well as of further CLIC Drive Beam modules. The tool has been tested extensively and its functionality has been verified. The phase error propagation at CLIC h...

Two-Phase Induction Motor Drives

Directory of Open Access Journals (Sweden)

Gholam Reza Arab Markadeh

2010-10-01

Full Text Available The lack of variable-speed drives for two (single induction motor is a reality. This article attempts mainly to investigate the reasons for this lack of variable – speed drives. This paper deals with literature survey of various existing converter topologies, which have been proposed for adjustable speed single phase induction motor drives. Various converter topologies have been compared in this paper. Among these converter topologies, the adjustable frequency PWM inverter is the best choice for single-phase induction motor drives. However, adjustable-frequency drives have not been widely used with single-phase Induction motors. The open-loop constant V/F control law cannot be used with the single-phase induction motor drives as it is used with three phase motors. The variation of the operating frequency at lower speed range with constant load torque causes variation in motor's slip. A constant V/F control is suitable only over the upper speed range.

Thermal and mechanical cyclic loading of thick spherical vessels made of transversely isotropic materials

International Nuclear Information System (INIS)

Komijani, M.; Mahbadi, H.; Eslami, M.R.

2013-01-01

The aim of this paper is to obtain the dependency of the ratcheting, reversed plasticity, or shakedown behavior of spherical vessels made of some anisotropic materials to the stress category of imposed cyclic loading. The Hill anisotropic yield criterion with the kinematic hardening theories of plasticity based on the Prager and Armstrong–Frederick models are used to predict the yield of the vessel and obtain the plastic strains. An iterative numerical method is used to simulate the cyclic loading behavior of the structure. The effect of mean and amplitude of the mechanical and thermal loads on cyclic behavior and ratcheting rate of the vessel is investigated respectively. The ratcheting rate for the vessels made of transversely isotropic material is evaluated for the various ratios of anisotropy. -- Highlights: ► Cyclic loading analysis of anisotropic spheres is assessed. ► Using the Prager model results in ratcheting. ► Armstrong-Frederick model predicts ratcheting for load controlled cyclic loadings. ► The A-F model predicts ratcheting to a stabilized cycle for thermal loadings

Summary of LaRC 2-inch Erectable Joint Hardware Heritage Test Data

Science.gov (United States)

Dorsey, John T.; Watson, Judith J.

2016-01-01

As the National Space Transportation System (STS, also known as the Space Shuttle) went into service during the early 1980's, NASA envisioned many missions of exploration and discovery that could take advantage of the STS capabilities. These missions included: large orbiting space stations, large space science telescopes and large spacecraft for manned missions to the Moon and Mars. The missions required structures that were significantly larger than the payload volume available on the STS. NASA Langley Research Center (LaRC) conducted studies to design and develop the technology needed to assemble the large space structures in orbit. LaRC focused on technology for erectable truss structures, in particular, the joint that connects the truss struts at the truss nodes. When the NASA research in large erectable space structures ended in the early 1990's, a significant amount of structural testing had been performed on the LaRC 2-inch erectable joint that was never published. An extensive set of historical information and data has been reviewed and the joint structural testing results from this historical data are compiled and summarized in this report.

Influence of unexpected events on driving behaviour at different hierarchical levels: a driving simulator experiment

NARCIS (Netherlands)

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

2008-01-01

Computer based simulation models of human driving behaviour can be used effectively to model driving and behavioural adaptation to Intelligent Transport System (ITS). This can be a useful step in human centered design of ITS. To construct a comprehensive model of driving behaviour, the interaction

Influence of unexpected events on driving behaviour at different hierarchical levels: A driving simulator experiment

NARCIS (Netherlands)

Schaap, Nina; van der Horst, A.R.A.; van Arem, Bart; Brusque, Corinne

2008-01-01

Computer based simulation models of human driving behaviour can be used effectively to model driving behaviour and behavioural adaptation to Intelligent Transport System (ITS). This can be a useful step in human centered design of ITS. To construct a comprehensive model of driving behaviour, the

[Driving and health at work].

Science.gov (United States)

Giorgio, Marie-Thérèse

2015-09-01

The role of the occupational physician is to prevent occupational accidents and diseases. Therefore, he is the one to decide if a worker is fit to drive in the context of his professional activity, including in cases where no specific driving license is required (e.g. forklift truck, mobile crane). This decision is an important one, as two thirds of fatal occupational accidents occur on the road. The decision is made on the basis of both a medical examination and the regulation, which indicates all contraindications to driving. The physician's responsibility is involved, as is the employer's, as he must ensure that his employee is fit to drive and possesses a valid driving license at all times. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Naturalistic driving observations of manual and visual-manual interactions with navigation systems and mobile phones while driving.

NARCIS (Netherlands)

Christoph, M. Nes, N. van & Knapper, A.

2014-01-01

This paper discusses a naturalistic driving study on the use of mobile phones and navigation systems while driving. Manual interactions with these devices while driving can cause distraction from the driving task and reduce traffic safety. In this study 21 subjects were observed for 5 weeks. Their

Piezoelectric drive circuit

Science.gov (United States)

Treu, C.A. Jr.

1999-08-31

A piezoelectric motor drive circuit is provided which utilizes the piezoelectric elements as oscillators and a Meacham half-bridge approach to develop feedback from the motor ground circuit to produce a signal to drive amplifiers to power the motor. The circuit automatically compensates for shifts in harmonic frequency of the piezoelectric elements due to pressure and temperature changes. 7 figs.

Commercial Truck Driver Health and Safety: Exploring Distracted Driving Performance and Self-Reported Driving Skill.

Science.gov (United States)

Stavrinos, Despina; Heaton, Karen; Welburn, Sharon C; McManus, Benjamin; Griffin, Russell; Fine, Philip R

2016-08-01

Reducing distracters detrimental to commercial truck driving is a critical component of improving the safety performance of commercial drivers, and makes the highways safer for all drivers. This study used a driving simulator to examine effects of cell phone, texting, and email distractions as well as self-reported driver optimism bias on the driving performance of commercial truck drivers. Results revealed that more visually demanding tasks were related to poorer driving performance. However, the cell phone task resulted in less off-the-road eye glances. Drivers reporting being "very skilled" displayed poorer driving performance than those reporting being "skilled." Onboard communication devices provide a practical, yet visually and manually demanding, solution for connecting drivers and dispatchers. Trucking company policies should minimize interaction between dispatchers and drivers when the truck is in motion. Training facilities should integrate driving simulators into the instruction of commercial drivers, targeting over-confident drivers. © 2016 The Author(s).

Introducing a multivariate model for predicting driving performance: the role of driving anger and personal characteristics.

Science.gov (United States)

Roidl, Ernst; Siebert, Felix Wilhelm; Oehl, Michael; Höger, Rainer

2013-12-01

Maladaptive driving is an important source of self-inflicted accidents and this driving style could include high speeds, speeding violations, and poor lateral control of the vehicle. The literature suggests that certain groups of drivers, such as novice drivers, males, highly motivated drivers, and those who frequently experience anger in traffic, tend to exhibit more maladaptive driving patterns compared to other drivers. Remarkably, no coherent framework is currently available to describe the relationships and distinct influences of these factors. We conducted two studies with the aim of creating a multivariate model that combines the aforementioned factors, describes their relationships, and predicts driving performance more precisely. The studies employed different techniques to elicit emotion and different tracks designed to explore the driving behaviors of participants in potentially anger-provoking situations. Study 1 induced emotions with short film clips. Study 2 confronted the participants with potentially anger-inducing traffic situations during the simulated drive. In both studies, participants who experienced high levels of anger drove faster and exhibited greater longitudinal and lateral acceleration. Furthermore, multiple linear regressions and path-models revealed that highly motivated male drivers displayed the same behavior independent of their emotional state. The results indicate that anger and specific risk characteristics lead to maladaptive changes in important driving parameters and that drivers with these specific risk factors are prone to experience more anger while driving, which further worsens their driving performance. Driver trainings and anger management courses will profit from these findings because they help to improve the validity of assessments of anger related driving behavior. © 2013.

Fast wave current drive

International Nuclear Information System (INIS)

Goree, J.; Ono, M.; Colestock, P.; Horton, R.; McNeill, D.; Park, H.

1985-07-01

Fast wave current drive is demonstrated in the Princeton ACT-I toroidal device. The fast Alfven wave, in the range of high ion-cyclotron harmonics, produced 40 A of current from 1 kW of rf power coupled into the plasma by fast wave loop antenna. This wave excites a steady current by damping on the energetic tail of the electron distribution function in the same way as lower-hybrid current drive, except that fast wave current drive is appropriate for higher plasma densities

Relationship of impaired-driving enforcement intensity to drinking and driving on the roads.

Science.gov (United States)

Fell, James C; Waehrer, Geetha; Voas, Robert B; Auld-Owens, Amy; Carr, Katherine; Pell, Karen

2015-01-01

It is principally the area of enforcement that offers the greatest opportunity for reducing alcohol-impaired driving in the near future. How much of a reduction in drinking and driving would be achieved by how much improvement in enforcement intensity? We developed logistic regression models to explore how enforcement intensity (6 different measures) related to the prevalence of weekend nighttime drivers in the 2007 National Roadside Survey who had been drinking (blood alcohol concentration [BAC] ≥ 0.00 g/dl), who had BACs ≥ 0.05 g/dl, and who were driving with an illegal BAC ≥ 0.08 g/dl. Drivers on the roads in our sample of 30 communities who were exposed to fewer than 228 traffic stops per 10,000 population aged 18 and older had 2.4 times the odds of being BAC positive, 3.6 times the odds of driving with a BAC ≥ 0.05, and 3.8 times the odds of driving with a BAC ≥ 0.08 compared to those drivers on the roads in communities with more than 1,275 traffic stops per 10,000 population. Drivers on the roads in communities with fewer than 3.7 driving under the influence (DUI) arrests per 10,000 population had 2.7 times the odds of BAC-positive drivers on the roads compared to communities with the highest intensity of DUI arrest activity (>38 DUI arrests per 10,000 population). The number of traffic stops and DUI arrests per capita were significantly associated with the odds of drinking and driving on the roads in these communities. This might reflect traffic enforcement visibility. The findings in this study may help law enforcement agencies around the country adjust their traffic enforcement intensity to reduce impaired driving in their community. Copyright © 2014 by the Research Society on Alcoholism.

Method for driving an actuator, actuator drive, and apparatus comprising an actuator

NARCIS (Netherlands)

2010-01-01

An actuator driver circuit includes a drive signal source and an electrical damping element having a negative resistance connected in series with the drive signal source. A controllable switch is provided for selectively switching the electrical damping element into or put of a signal path from a

Comparing a driving simulator to the real road regarding distracted driving speed

NARCIS (Netherlands)

Knapper, Allert; Christoph, Michiel; Hagenzieker, Marjan; Brookhuis, Karel

2015-01-01

Relative and absolute validity of a driving simulator were assessed regarding effects on mean speed and speed variation during distracting secondary tasks, and normal driving. 16 participants drove the same route four times, twice in a simulator and twice in the real world. They performed way

Comparing a driving simulator to the real road regarding distracted driving speed.

NARCIS (Netherlands)

Knapper, A. Christoph, M. Hagenzieker, M. & Brookhuis, K.

2015-01-01

Relative and absolute validity of a driving simulator were assessed regarding effects on mean speed and speed variation during distracting secondary tasks, and normal driving. 16 participants drove the same route four times, twice in a simulator and twice in the real world. They performed way

Multi-Motor Drives for Crane Application

Directory of Open Access Journals (Sweden)

MITROVIC, N.

2009-10-01

Full Text Available This paper focuses on the application of adjustable speed induction motor drives for gantry cranes. Modern solution considers application of frequency converters for all drives. Multi-motor drives are standard solutions in crane application and requirements of load sharing are present. Presented algorithm provides load sharing proportional to the rated motor power on the simple and practically applicable method on the basis of estimated torques by frequency converters, and controller realized in PLC. Special attention is devoted to wide span gantry drive and algorithm for skew elimination. Solutions for load distribution in multi-motor drive, as well as mode of gantry drive skew elimination, are described. Suggested solution concept is confirmed by the experimental results.

Driving Force Filtering and Driving Mechanism Analysis of Urban Agricultural Development in Weifang County, China

Directory of Open Access Journals (Sweden)

SUI Fei-fei

2016-03-01

Full Text Available As an agricultural nation, the agricultural landscape is the basic appearance and existence in China, but the common existence often be neglected and contempted. As a new type of design and ideology, the development of urban agricultural landscape will greatly affect the texture and structure of the urban space. According to the urban agricultural production data and the socio-economic data of Weifang County, a set of evaluation index system that could analyze quantitatively the driving force of urban agricultural production changes and the internal drive mechanism was built. The original driving force indicators of economy, society, resources and environment from the time-series were chosen, and then 15 driving forces from the original driving forces by correlation analysis and principal component analysis were selected. The degree of influence was analyzed and the driving forces model by means of partial least squares(PLS was built. The results demonstrated that the factors greatly influenced the increase of urban agricultural output value in Weifang County were per capita net income of rural residents, agricultural machinery total power, effective irrigation area, centralized treatment rate of urban sewage, with the driving exponents 0.2509, 0.1019, 0.1655, 0.1332, respectively. The negative influence factor was the use amount of agricultural plastic film and the driving exponent was-0.2146. The research provides a reference for the development of urban agriculture, as well as a reference for the related study.

Autonomous Agent-Based Systems and Their Applications in Fluid Dynamics, Particle Separation, and Co-evolving Networks

Science.gov (United States)

Graeser, Oliver

This thesis comprises three parts, reporting research results in Fluid Dynamics (Part I), Particle Separation (Part II) and Co-evolving Networks (Part III). Part I deals with the simulation of fluid dynamics using the lattice-Boltzmann method. Microfluidic devices often feature two-dimensional, repetitive arrays. Flows through such devices are pressure-driven and confined by solid walls. We have defined new adaptive generalised periodic boundary conditions to represent the effects of outer solid walls, and are thus able to exploit the periodicity of the array by simulating the flow through one unit cell in lieu of the entire device. The so-calculated fully developed flow describes the flow through the entire array accurately, but with computational requirements that are reduced according to the dimensions of the array. Part II discusses the problem of separating macromolecules like proteins or DNA coils. The reliable separation of such molecules is a crucial task in molecular biology. The use of Brownian ratchets as mechanisms for the separation of such particles has been proposed and discussed during the last decade. Pressure-driven flows have so far been dismissed as possible driving forces for Brownian ratchets, as they do not generate ratchet asymmetry. We propose a microfluidic design that uses pressure-driven flows to create asymmetry and hence allows particle separation. The dependence of the asymmetry on various factors of the microfluidic geometry is discussed. We further exemplify the feasibility of our approach using Brownian dynamics simulations of particles of different sizes in such a device. The results show that ratchet-based particle separation using flows as the driving force is possible. Simulation results and ratchet theory predictions are in excellent agreement. Part III deals with the co-evolution of networks and dynamic models. A group of agents occupies the nodes of a network, which defines the relationship between these agents. The

ECO-DRIVING MODELING ENVIRONMENT

Science.gov (United States)

2015-11-01

This research project aims to examine the eco-driving modeling capabilities of different traffic modeling tools available and to develop a driver-simulator-based eco-driving modeling tool to evaluate driver behavior and to reliably estimate or measur...

Driving and Age-Related Macular Degeneration

OpenAIRE

Owsley, Cynthia; McGwin, Gerald

2008-01-01

This article reviews the research literature on driving and age-related macular degeneration, which is motivated by the link between driving and the quality of life of older adults and their increased collision rate. It addresses the risk of crashes, driving performance, driving difficulty, self-regulation, and interventions to enhance, safety, and considers directions for future research.

Risky driving and lifestyles in adolescence.

Science.gov (United States)

Bina, Manuela; Graziano, Federica; Bonino, Silvia

2006-05-01

Several studies have shown that risky driving is especially prevalent among young drivers and recent research has pointed out that driving in adolescence should be investigated in the more general context of adolescent development. The first aim of this contribution was to analyze involvement in risky driving in a normative sample of 645 Italian adolescents, boys and girls, aged 14-17, through a self-report questionnaire. A second aim was to evaluate the association between risky driving and lifestyle, defined as involvement in other health risk behaviors and leisure activities. The main results showed that many adolescents drove cars and motorcycles without the required driving license and the most frequent offences were speeding and failure to maintain a safe braking distance. Gender and age differences were also investigated. Results concerning the association between risky driving and lifestyle showed that risky driving was not an isolated behavior. Boys who displayed risky driving practices were more likely to adopt a lifestyle characterized by high involvement in antisocial behaviors, tobacco smoking, comfort eating and time spent in non-organized activities with friends. Girls involved in risky driving were more likely to be involved in other risk-taking behaviors, antisocial behaviors and drug use.

Driving, brain injury and assistive technology.

Science.gov (United States)

Lane, Amy K; Benoit, Dana

2011-01-01

Individuals with brain injury often present with cognitive, physical and emotional impairments which impact their ability to resume independence in activities of daily living. Of those activities, the resumption of driving privileges is cited as one of the greatest concerns by survivors of brain injury. The integration of driving fundamentals within the hierarchical model proposed by Keskinen represents the complexity of skills and behaviors necessary for driving. This paper provides a brief review of specific considerations concerning the driver with TBI and highlights current vehicle technology which has been developed by the automotive industry and by manufacturers of adaptive driving equipment that may facilitate the driving task. Adaptive equipment technology allows for compensation of a variety of operational deficits, whereas technological advances within the automotive industry provide drivers with improved safety and information systems. However, research has not yet supported the use of such intelligent transportation systems or advanced driving systems for drivers with brain injury. Although technologies are intended to improve the safety of drivers within the general population, the potential of negative consequences for drivers with brain injury must be considered. Ultimately, a comprehensive driving evaluation and training by a driving rehabilitation specialist is recommended for individuals with brain injury. An understanding of the potential impact of TBI on driving-related skills and knowledge of current adaptive equipment and technology is imperative to determine whether return-to-driving is a realistic and achievable goal for the individual with TBI.

Decoupling control of steering and driving system for in-wheel-motor-drive electric vehicle

Science.gov (United States)

Zhang, Han; Zhao, Wanzhong

2018-02-01

To improve the maneuverability and stability of in-wheel-motor-drive electric vehicle, a control strategy based on nonlinear decoupling control method is proposed in this paper, realizing the coordinated control of the steering and driving system. At first, the nonlinear models of the in-wheel-motor-drive electric vehicle and its sub-system are constructed. Then the inverse system decoupling theory is applied to decompose the nonlinear system into several independent subsystems, which makes it possible to realize the coordinated control of each subsystem. Next, the μ-Synthesis theory is applied to eliminate the influence of model uncertainty, improving the stability, robustness and tracking performance of in-wheel-motor-drive electric vehicle. Simulation and experiment results and numerical analyses, based on the electric vehicle actuated by in-wheel-motors, prove that the proposed control method is effective to accomplish the decoupling control of the steering and driving system in both simulation and real practice.

Visually impaired drivers who use bioptic telescopes: self-assessed driving skills and agreement with on-road driving evaluation.

Science.gov (United States)

Owsley, Cynthia; McGwin, Gerald; Elgin, Jennifer; Wood, Joanne M

2014-01-15

To compare self-assessed driving habits and skills of licensed drivers with central visual loss who use bioptic telescopes to those of age-matched normally sighted drivers, and to examine the association between bioptic drivers' impressions of the quality of their driving and ratings by a "backseat" evaluator. Participants were licensed bioptic drivers (n = 23) and age-matched normally sighted drivers (n = 23). A questionnaire was administered addressing driving difficulty, space, quality, exposure, and, for bioptic drivers, whether the telescope was helpful in on-road situations. Visual acuity and contrast sensitivity were assessed. Information on ocular diagnosis, telescope characteristics, and bioptic driving experience was collected from the medical record or in interview. On-road driving performance in regular traffic conditions was rated independently by two evaluators. Like normally sighted drivers, bioptic drivers reported no or little difficulty in many driving situations (e.g., left turns, rush hour), but reported more difficulty under poor visibility conditions and in unfamiliar areas (P Driving exposure was reduced in bioptic drivers (driving 250 miles per week on average vs. 410 miles per week for normally sighted drivers, P = 0.02), but driving space was similar to that of normally sighted drivers (P = 0.29). All but one bioptic driver used the telescope in at least one driving task, and 56% used the telescope in three or more tasks. Bioptic drivers' judgments about the quality of their driving were very similar to backseat evaluators' ratings. Bioptic drivers show insight into the overall quality of their driving and areas in which they experience driving difficulty. They report using the bioptic telescope while driving, contrary to previous claims that it is primarily used to pass the vision screening test at licensure.

Neuropsychological assessment of driving ability and self-evaluation: a comparison between driving offenders and a control group.

Science.gov (United States)

Zingg, Christina; Puelschen, Dietrich; Soyka, Michael

2009-12-01

The relationship between performance in neuropsychological tests and actual driving performance is unclear and results of studies on this topic differ. This makes it difficult to use neuropsychological tests to assess driving ability. The ability to compensate cognitive deficits plays a crucial role in this context. We compared neuropsychological test results and self-evaluation ratings between three groups: driving offenders with a psychiatric diagnosis relevant for driving ability (mainly alcohol dependence), driving offenders without such a diagnosis and a control group of non-offending drivers. Subjects were divided into two age categories (19-39 and 40-66 years). It was assumed that drivers with a psychiatric diagnosis relevant for driving ability and younger driving offenders without a psychiatric diagnosis would be less able to adequately assess their own capabilities than the control group. The driving offenders with a psychiatric diagnosis showed poorer concentration, reactivity, cognitive flexibility and problem solving, and tended to overassess their abilities in intelligence and attentional functions, compared to the other two groups. Conversely, younger drivers rather underassessed their performance.

Drunk driving among novice drivers, possible prevention with additional psychological module in driving school curriculum.

Science.gov (United States)

Eensoo, Diva; Paaver, Marika; Harro, Jaanus

2011-01-01

Road traffic collisions caused by drunk driving pose a significant public health problem all over the world. Therefore additional preventive activities against drunk driving should be worked out. The aim of the study was to assess drunk driving in novice drivers after a psychological intervention taking into account also impulsivity, law obedience, and alcohol-related measures. An intervention study was started with 1889 car driver's license attempters during their driving school studies. Subjects were classified as intervention group (n=1083, mean age 23.1 (SD=7.4) years), control group (n=517, mean age 22.8 (SD=7.1) years) and "lost" group (n=289, mean age 23.0 (SD=6.9) years). "Lost" group subjects had been assigned into the intervention group, but they did not participate in the intervention. Subjects of the intervention group participated in a psychological intervention on the dangers of impulsive behavior in traffic. After a three year follow-up period it appeared that in the control group and in the lost group there was a significantly higher proportion of drunk drivers than in the intervention group, 3.3% (n=17), 3.5% (n=10) and 1.5% (n=10) (p=0.026), respectively. Survival analysis confirmed that psychological intervention had a significant impact on drunk driving (p=0.015), and the impact of the intervention was persistent also in the case of higher scores in Mild social deviance. In subjects with higher scores in impulsivity measures and alcohol-related problems the impact of short psychological intervention was not sufficient for preventing drunk driving. It can be concluded that psychological intervention used during the driving school studies is an effective primary prevention activity against drunk driving. However, for drivers with high scores in impulsivity measures and alcohol-related problems, the short psychological intervention is not sufficient in reducing drunk driving behavior.

In Patients with Cirrhosis, Driving Simulator Performance is Associated With Real-life Driving

DEFF Research Database (Denmark)

Lauridsen, Mette Enok Munk; Thacker, Leroy R; White, Melanie B

2016-01-01

BACKGROUND & AIMS: Minimal hepatic encephalopathy (MHE) has been linked to higher real-life rates of automobile crashes and poor performance in driving simulation studies, but the link between driving simulator performance and real-life automobile crashes has not been clearly established. Further......, not all patients with MHE are unsafe drivers, but it is unclear how to distinguish them from unsafe drivers. We investigated the link between performance on driving simulators and real-life automobile accidents and traffic violations. We also aimed to identify features of unsafe drivers with cirrhosis...... and evaluated changes in simulated driving skills and MHE status after 1 year. METHODS: We performed a study of outpatients with cirrhosis (n=205; median 55 years old; median model for end-stage liver disease score, 9.5; none with overt hepatic encephalopathy or alcohol or illicit drug use within previous 6...

Testing device for control rod drives

International Nuclear Information System (INIS)

Hayakawa, Toshifumi.

1992-01-01

A testing device for control rod drives comprises a logic measuring means for measuring an output signal from a control rod drive logic generation circuit, a control means for judging the operation state of a control rod and a man machine interface means for outputting the result of the judgement. A driving instruction outputted from the control rod operation device is always monitored by the control means, and if the operation instruction is stopped, a testing signal is outputted to the control rod control device to simulate a control rod operation. In this case, the output signal of the control rod drive logic generation circuit is held in a control rod drive memory means and intaken into a logic analysis means for measurement and an abnormality is judged by the control means. The stopping of the control rod drive instruction is monitored and the operation abnormality of the control rod is judged, to mitigate the burden of an operator. Further, the operation of the control rod drive logic generation circuit can be confirmed even during a nuclear plant operation by holding the control rod drive instruction thereby enabling to improve maintenance efficiency. (N.H.)

Diplopia and driving: a problematic issue.

Science.gov (United States)

Righi, Stefano; Boffano, Paolo; Guglielmi, Valeria; Rossi, Paolo; Martorina, Massimo

2014-10-01

The aim of this article was to review the literature regarding diplopia and driving license and to review the West European legislations about this topic, in order to obtain appropriate indications for hospitals specialists and patients. A systematic review of articles published about diplopia and driving was performed. In addition a review of West European national legislations about driving license regulations for medical illnesses was performed, in addition to the European Union Directive on driving licenses. In the literature, the presence of diplopia has not been considered a reliable predictor of the safety of driving behavior, or it has not appeared to be a contraindication for driving according to some authors who were unable to demonstrate significant differences on driving simulator performance between subjects with chronic stable diplopia and control subjects. Nevertheless, in all western European legislations, acute diplopia constitutes an important limitation for driving, thus making the knowledge of current regulations fundamental for specialists involved in managing patients with diplopia. Ophthalmologists and maxillofacial/head and neck surgeons, may advise patients before hospital discharge about current legislations in their respective countries. Copyright © 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Risky driving behaviors in Tehran, Iran.

Science.gov (United States)

Shams, Mohsen; Rahimi-Movaghar, Vafa

2009-03-01

Iran has one of the highest fatality rates due to road traffic crashes (RTC) in the world. The disability adjusted life years (DALYs) for RTC in Iran is more than 1,300,000 years, which is more than that for any other disease such as cardiovascular or cancer. We evaluated risky driving behaviors in Tehran, the capital of Iran. A retrospective analysis was conducted based on the data obtained from the Tehran Police Safety Driving Department. Offenses and crashes were studied in different municipal districts in Tehran from March 2006 to March 2007. The inclusion criteria were risky driving behaviors fined by the police. Nonbehavioral offences were excluded. There were 3,821,798 offenses in Tehran. Not wearing a seat belt was the most common (59%) example of risky driving behavior, followed by tailgating, not wearing motorcycle helmets, talking on the cell phone while driving, overtaking from the wrong side, speeding, not driving between the lanes, weaving in and out of traffic, left deviation, and changing lanes without signals. The most common causes of RTC in Tehran are speeding, overtaking from the wrong side, and the rapid changing of driving lanes. The study factors effective in preventing risky driving behaviors in Tehran is recommended. The consideration of specific characteristics of the municipal districts is necessary to reduce risky driving behaviors.

Driving patterns in older adults with glaucoma.

Science.gov (United States)

van Landingham, Suzanne W; Hochberg, Chad; Massof, Robert W; Chan, Emilie; Friedman, David S; Ramulu, Pradeep Y

2013-02-21

The ability to drive is important for ensuring quality of life for many older adults. Glaucoma is prevalent in this age group and may affect driving. The purpose of this study is to determine if glaucoma and glaucomatous visual field (VF) loss are associated with driving cessation, limitations, and deference to another driver in older adults. Cross-sectional study. Eighty-one glaucoma subjects and 58 glaucoma suspect controls between age 60 and 80 reported if they had ceased driving, limited their driving in various ways, or preferred another to drive. Twenty-three percent of glaucoma subjects and 6.9% of suspects had ceased driving (p = 0.01). Glaucoma subjects also had more driving limitations than suspects (2.0 vs. 1.1, p = 0.007). In multivariable models, driving cessation was more likely for glaucoma subjects as compared to suspects (OR = 4.0; 95% CI = 1.1-14.7; p = 0.03). The odds of driving cessation doubled with each 5 decibel (dB) decrement in the better-eye VF mean deviation (MD) (OR = 2.0; 95% CI = 1.4-2.9; p driving limitations (OR = 4.7; 95% CI = 1.3-16.8; p = 0.02). The likelihood of reporting more limitations increased with the VF loss severity (OR = 1.6 per 5 dB decrement in the better-eye VF MD; 95% CI = 1.1-2.4; p = 0.02). Neither glaucoma nor VF MD was associated with other driver preference (p > 0.1 for both). Glaucoma and glaucomatous VF loss are associated with greater likelihood of driving cessation and greater limitation of driving in the elderly. Further prospective study is merited to assess when and why people with glaucoma change their driving habits, and to determine if their observed self-regulation of driving is adequate to ensure safety.

Perceptual and Cognitive Impairments and Driving

Science.gov (United States)

Korner-Bitensky, Nicol; Coopersmith, Henry; Mayo, Nancy; Leblanc, Ginette; Kaizer, Franceen

1990-01-01

Perceptual and cognitive disorders that frequently accompany stroke and head injury influence an individual's ability to drive a motor vehicle. Canadian physicians are legally responsible for identifying patients who are potentially unsafe to drive and, if they fail to do so, may be held liable in a civil action suit. The authors review the guidelines for physicians evaluating a patient's fitness to drive after brain injury. They also examine the actions a physician should take when a patient with perceptual and cognitive problems wants to drive. Ultimately, by taking these actions, physicians will help to prevent driving accidents. PMID:21234047

Analysis of Vehicle Steering and Driving Bifurcation Characteristics

Directory of Open Access Journals (Sweden)

Xianbin Wang

2015-01-01

Full Text Available The typical method of vehicle steering bifurcation analysis is based on the nonlinear autonomous vehicle model deriving from the classic two degrees of freedom (2DOF linear vehicle model. This method usually neglects the driving effect on steering bifurcation characteristics. However, in the steering and driving combined conditions, the tyre under different driving conditions can provide different lateral force. The steering bifurcation mechanism without the driving effect is not able to fully reveal the vehicle steering and driving bifurcation characteristics. Aiming at the aforementioned problem, this paper analyzed the vehicle steering and driving bifurcation characteristics with the consideration of driving effect. Based on the 5DOF vehicle system dynamics model with the consideration of driving effect, the 7DOF autonomous system model was established. The vehicle steering and driving bifurcation dynamic characteristics were analyzed with different driving mode and driving torque. Taking the front-wheel-drive system as an example, the dynamic evolution process of steering and driving bifurcation was analyzed by phase space, system state variables, power spectral density, and Lyapunov index. The numerical recognition results of chaos were also provided. The research results show that the driving mode and driving torque have the obvious effect on steering and driving bifurcation characteristics.

Low backlash direct drive actuator

Science.gov (United States)

Kuklo, Thomas C.

1994-01-01

A low backlash direct drive actuator is described which comprises a motor such as a stepper motor having at least 200 steps per revolution; a two part hub assembly comprising a drive hub coaxially attached to the shaft of the motor and having a plurality of drive pins; a driven hub having a plurality of bores in one end thereof in alignment with the drive pins in the drive hub and a threaded shaft coaxially mounted in an opposite end of the driven hub; and a housing having a central bore therein into which are fitted the drive hub and driven hub, the housing having a motor mount on one end thereof to which is mounted the stepper motor, and a closed end portion with a threaded opening therein coaxial with the central bore in the housing and receiving therein the threaded shaft attached to the driven hub. Limit switches mounted to the housing cooperate with an enlarged lip on the driven hub to limit the lateral travel of the driven hub in the housing, which also acts to limit the lateral travel of the threaded shaft which functions as a lead screw.

Continuing to drive while sleepy: the influence of sleepiness countermeasures, motivation for driving sleepy, and risk perception.

Science.gov (United States)

Watling, Christopher N; Armstrong, Kerry A; Obst, Patricia L; Smith, Simon S

2014-12-01

Driver sleepiness is a major contributor to road crashes. The current study sought to examine the association between perceptions of effectiveness of six sleepiness countermeasures and their relationship with self-reports of continuing to drive while sleepy among 309 drivers after controlling for the influence of age, sex, motivation for driving sleepy, and risk perception of sleepy driving. The results demonstrate that the variables of age, sex, motivation, and risk perception were significantly associated with self-reports of continuing to drive while sleepy and only one countermeasure was associated with self-reports of continuing to drive while sleepy. Further, it was found that age differences in self-reports of continuing to drive while sleepy was mediated by participants' motivation and risk perception. These findings highlight modifiable factors that could be focused on with interventions that seek to modify drivers' attitudes and behaviours of driving while sleepy. Copyright © 2014 Elsevier Ltd. All rights reserved.

Driving error and anxiety related to iPod mp3 player use in a simulated driving experience.

Science.gov (United States)

Harvey, Ashley R; Carden, Randy L

2009-08-01

Driver distraction due to cellular phone usage has repeatedly been shown to increase the risk of vehicular accidents; however, the literature regarding the use of other personal electronic devices while driving is relatively sparse. It was hypothesized that the usage of an mp3 player would result in an increase in not only driving error while operating a driving simulator, but driver anxiety scores as well. It was also hypothesized that anxiety scores would be positively related to driving errors when using an mp3 player. 32 participants drove through a set course in a driving simulator twice, once with and once without an iPod mp3 player, with the order counterbalanced. Number of driving errors per course, such as leaving the road, impacts with stationary objects, loss of vehicular control, etc., and anxiety were significantly higher when an iPod was in use. Anxiety scores were unrelated to number of driving errors.

Implicit attitudes towards risky and safe driving

DEFF Research Database (Denmark)

Martinussen, Laila Marianne; Sømhovd, Mikael Julius; Møller, Mette

; further, self-reports of the intention to drive safely (or not) are socially sensitive. Therefore, we examined automatic preferences towards safe and risky driving with a Go/No-go Association Task (GNAT). The results suggest that (1) implicit attitudes towards driving behavior can be measured reliably...... with the GNAT; (2) implicit attitudes towards safe driving versus towards risky driving may be separable constructs. We propose that research on driving behavior may benefit from routinely including measures of implicit cognition. A practical advantage is a lesser susceptibility to social desirability biases......, compared to self-report methods. Pending replication in future research, the apparent dissociation between implicit attitudes towards safe versus risky driving that we observed may contribute to a greater theoretical understanding of the causes of unsafe and risky driving behavior....

Comparison of Unsafe Driving Across Medical Conditions.

Science.gov (United States)

Moon, Sanghee; Ranchet, Maud; Tant, Mark; Akinwuntan, Abiodun E; Devos, Hannes

2017-09-01

To compare risks of unsafe driving in patients with medical conditions. This large population-based study included all patients who were referred for a fitness-to-drive evaluation at an official driving evaluation center in 2013 and 2014. Risks of unsafe driving included physician's fitness-to-drive recommendation, comprehensive fitness-to-drive decision, motor vehicle crash history, and traffic violation history. A total of 6584 patients were included in the study. Risks of unsafe driving were significantly different across medical conditions (Pdriving. Patients with psychiatric conditions or substance abuse did worse on most driving safety outcomes, despite their low representation in the total sample (359 [6%] and 46 [1%], respectively). The risk of unsafe driving varied greatly across medical conditions. Sensitization campaigns, education, and medical guidelines for physicians and driver licensing authorities are warranted to identify patients at risk, especially for those with psychiatric conditions and substance abuse problems. Copyright © 2017 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.

Effects of chewing gum on driving performance as evaluated by the STISIM driving simulator

OpenAIRE

Yoo, Ingyu; Kim, Eun-Joo; Lee, Joo-Hyun

2015-01-01

[Purpose] The purpose of this study was to determine the effects of chewing gum on driving performance in a driving simulator. [Subjects] In total, 26 young licensed drivers participated. [Methods] The driving scenario was typical of an urban environment: a single-carriageway, two-way road consisting of a mix of curved and straight sections, with considerable levels of traffic, pedestrians, and parked cars. Mean distance driven above the speed limit, lane position, mean distance driven across...

Correlates of Marijuana Drugged Driving and Openness to Driving While High: Evidence from Colorado and Washington.

Directory of Open Access Journals (Sweden)

Kevin C Davis

Full Text Available A potential unintended consequence of legalizing recreational marijuana is increased marijuana-related driving impairment. Some states where recreational marijuana is legal have begun implementing interventions to mitigate driving under the influence (DUI of marijuana, including media campaigns to increase knowledge about DUI laws. However, little is known about the associations between knowledge of DUI laws and marijuana DUI behavior. In this study, we provide new data from a survey of marijuana users in Colorado and Washington to examine associations between marijuana drugged driving and two potential behavioral precursors of marijuana DUI. We also explore other factors that may influence marijuana DUI.Data are from an online survey of marijuana users in Colorado and Washington. Respondents who reported any marijuana use in the past 30 days (n = 865 served as the analytic sample. We examined prevalence of two behavioral outcomes: (1 any driving of a motor vehicle while high in the past year and (2 driving a motor vehicle within 1 hour of using marijuana 5 or more times in the past month. Additional outcomes measuring willingness to drive while high were also assessed. Logistic regressions were used to estimate each outcome as a function of two multi-item scales measuring knowledge of the legal consequences of driving high and perceptions that driving while high is not safe. Additional covariates for potential confounders were included in each model.Prevalence of past-year driving while under the influence of marijuana was 43.6% among respondents. The prevalence of driving within 1 hour of using marijuana at least 5 times in the past month was 23.9%. Increased perception that driving high is unsafe was associated with lower odds of past-year marijuana DUI (OR = 0.31, P < 0.01 and lower past-month odds of driving 5 or more times within 1 hour of using marijuana (OR = 0.26, P < 0.01. Increased knowledge of marijuana DUI laws was also associated

Assessment of the MARS-KS Code Using Atlas 6-inch cold leg Break Test

Energy Technology Data Exchange (ETDEWEB)

Kang, D. G.; Kim, J. S.; Ahn, S. H.; Seul, K. W. [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

2012-03-15

An integral effect test on the SBLOCA (Small-Break Loss of Coolant Accident) aiming at 6-inch cold leg bottom break, SB-CL-09, was conducted with the Atlas on November, 13, 2009, by KAERI. In this study, the calculations using MARS-KS Vt1.2 code were conducted for 6-inch cold leg break test of Atlas (SB-CL-09) which is the second domestic standard problem (Dsp-02) to assess MARS-KS code capability to simulate the transient thermal-hydraulic behavior for SBLOCA. The steady state was determined by conducting a null transient calculation and the errors between the calculated and measured values are acceptable for almost primary/secondary system parameters. The predicted pressurizer pressure agrees relatively well with the experimental data and the predicted break flow and mass are in good agreement with experiment. In MARS-KS calculation, the decrease of core collapsed water level is predicted well in blowdown phase, but just before LSC, water level is higher than experiment. However, the sudden decrease and increase of water level is higher than experiment. However, the sudden decrease and increase of water level at the LSC are predicted qualitatively. After LSC, there is another water level dip at Sit injection time which is not in experiment. It is considered that this phenomenon is caused by rapid depressurization of downcomer due to significant condensation rate of vapor in downcomer when Sit water flows in it. For the downcomer water level is predicted well, however, it is significantly over-predicted at SIT injection time, water level is predicted well, however, it is significantly over-predicted at SIT injection time after SIT water flows in downcomer. Predicted cladding temperature generally agrees well with the experiment, while there is peak at SIT injection time in calculation which is not in experiment. The loop seals of 1A, 2B intermediate leg are cleared around 400 seconds in experiment, while only that of 1A is cleared in MARS-KS calculation at the

German taxi drivers' experiences and expressions of driving anger: Are the driving anger scale and the driving anger expression inventory valid measures?

Science.gov (United States)

Brandenburg, Stefan; Oehl, Michael; Seigies, Kristin

2017-11-17

The objective of this article was 2-fold: firstly, we wanted to examine whether the original Driving Anger Scale (DAS) and the original Driving Anger Expression Inventory (DAX) apply to German professional taxi drivers because these scales have previously been given to professional and particularly to nonprofessional drivers in different countries. Secondly, we wanted to examine possible differences in driving anger experience and expression between professional German taxi drivers and nonprofessional German drivers. We applied German versions of the DAS, the DAX, and the State-Trait Anger Expression Inventory (STAXI) to a sample of 138 professional German taxi drivers. We then compared their ratings to the ratings of a sample of 1,136 nonprofessional German drivers (Oehl and Brandenburg n.d. ). Regarding our first objective, confirmatory factor analysis shows that the model fit of the DAS is better for nonprofessional drivers than for professional drivers. The DAX applies neither to professional nor to nonprofessional German drivers properly. Consequently, we suggest modified shorter versions of both scales for professional drivers. The STAXI applies to both professional and nonprofessional drivers. With respect to our second objective, we show that professional drivers experience significantly less driving anger than nonprofessional drivers, but they express more driving anger. We conclude that the STAXI can be applied to professional German taxi drivers. In contrast, for the DAS and the DAX we found particular shorter versions for professional taxi drivers. Especially for the DAX, most statements were too strong for German drivers to agree to. They do not show behaviors related to driving anger expression as they are described in the DAX. These problems with the original American DAX items are in line with several other studies in different countries. Future investigations should examine whether (professional) drivers from further countries express their anger

Hypnotics and driving safety: meta-analyses of randomized controlled trials applying the on-the-road driving test.

Science.gov (United States)

Verster, Joris C; Veldhuijzen, Dieuwke S; Patat, Alain; Olivier, Berend; Volkerts, Edmund R

2006-01-01

Many people who use hypnotics are outpatients and are likely to drive a car the day after drug intake. The purpose of these meta-analyses was to determine whether or not this is safe. Placebo-controlled, randomized, double-blind trials were selected if using the on-the-road driving test to determine driving ability the day following one or two nights of treatment administration. Primary outcome measure of the driving test was the Standard Deviation of Lateral Position (SDLP); i.e., the weaving of the car. Fixed effects model meta-analyses were performed. Effect size (ES) was computed using mean standardized (weighted) difference scores between treatment and corresponding placebo SDLP values. Ten studies, published from 1984 to 2002 (207 subjects), were included in the meta-analyses. The morning following bedtime administration, i.e. 10-11 hours after dosing, significant driving impairment was found for the recommended dose of various benzodiazepine hypnotics (ES=0.42; 95% Confidence Interval (CI)=0.14 to 0.71). Twice the recommended dose impaired driving both in the morning (ES=0.68; CI=0.39 to 0.97) and afternoon, i.e. 16-17 hours after dosing (ES=0.57; CI=0.26 to 0.88). Zopiclone 7.5 mg also impaired driving in the morning (ES=0.89; CI=0.54 to 1.23). Zaleplon (10 and 20 mg) and zolpidem (10 mg) did not affect driving performance the morning after dosing. Following middle-of-the-night administration, significantly impaired driving performance was found for zopiclone 7.5 mg (ES=1.51, CI=0.85 to 2.17), zolpidem 10 mg (ES=0.66, CI=0.13 to 1.19) and zolpidem 20 mg (ES=1.16, CI=0.60 to 1.72). Zaleplon (10 and 20 mg) did not affect driving performance. The analyses show that driving a car the morning following nocturnal treatment with benzodiazepines and zopiclone is unsafe, whereas the recommended dose of zolpidem (10 mg) and zaleplon (10 mg) do not affect driving ability.

Fundamentals of electrical drives

CERN Document Server

Veltman, André; De Doncker, Rik W

2007-01-01

Provides a comprehensive introduction to various aspects of electrical drive systems. This volume provides a presentation of dynamic generic models that cover all major electrical machine types and modulation/control components of a drive as well as dynamic and steady state analysis of transformers and electrical machines.

Pilot Efficacy of a DriveFocus™ Intervention on the Driving Performance of Young Drivers

Directory of Open Access Journals (Sweden)

Liliana Alvarez

2018-05-01

Full Text Available Road traffic injuries are the leading cause of death for youth between the ages of 15 and 29 around the world. A need remains for evidence-based interventions that can improve the underlying skills of young drivers, including hazard perception and anticipation. This pilot study investigated the preliminary impact of a six session DriveFocus™ intervention on the ability of young novice drivers (mean age = 18.6, SD = 2.12 to detect (visual scanning, and respond (adjustment to stimuli to critical roadway information. Using a CDS-200 DriveSafety™ simulator, drives were recorded and sent to a blinded evaluator (occupational therapist, who scored the recorded drives for number and type (visual scanning and adjustment to stimuli of errors. We observed a statistically significant decline in the number of visual scanning [t(34 = 2.853, p = 0.007], adjustment to stimuli [t(34 = 3.481, p = 0.001], and total driving errors [t(34 = 3.481, p = 0.002], among baseline and post-test 2.

The prosocial and aggressive driving inventory (PADI): a self-report measure of safe and unsafe driving behaviors.

Science.gov (United States)

Harris, Paul B; Houston, John M; Vazquez, Jose A; Smither, Janan A; Harms, Amanda; Dahlke, Jeffrey A; Sachau, Daniel A

2014-11-01

Surveys of 1217 undergraduate students supported the reliability (inter-item and test-retest) and validity of the Prosocial and Aggressive Driving Inventory (PADI). Principal component analyses on the PADI items yielded two scales: Prosocial Driving (17 items) and Aggressive Driving (12 items). Prosocial Driving was associated with fewer reported traffic accidents and violations, with participants who were older and female, and with lower Boredom Susceptibility and Hostility scores, and higher scores on Agreeableness, Conscientiousness, Openness, and Neuroticism. Aggressive Driving was associated with more frequent traffic violations, with female participants, and with higher scores on Competitiveness, Sensation Seeking, Hostility, and Extraversion, and lower scores on Conscientiousness, Agreeableness, and Openness. The theoretical and practical implications of the PADI's dual focus on safe and unsafe driving are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Naturalistic drive cycle synthesis for pickup trucks.

Science.gov (United States)

Liu, Zifan; Ivanco, Andrej; Filipi, Zoran

2015-09-01

Future pick-up trucks are meeting much stricter fuel economy and exhaust emission standards. Design tradeoffs will have to be carefully evaluated to satisfy consumer expectations within the regulatory and cost constraints. Boundary conditions will obviously be critical for decision making: thus, the understanding of how customers are driving in naturalistic settings is indispensable. Federal driving schedules, while critical for certification, do not capture the richness of naturalistic cycles, particularly the aggressive maneuvers that often shape consumer perception of performance. While there are databases with large number of drive cycles, applying all of them directly in the design process is impractical. Therefore, representative drive cycles that capture the essence of the naturalistic driving should be synthesized from naturalistic driving data. Naturalistic drive cycles are firstly categorized by investigating their micro-trip components, defined as driving activities between successive stops. Micro-trips are expected to characterize underlying local traffic conditions, and separate different driving patterns. Next, the transitions from one vehicle state to another vehicle state in each cycle category are captured with Transition Probability Matrix (TPM). Candidate drive cycles can subsequently be synthesized using Markov Chain based on TPMs for each category. Finally, representative synthetic drive cycles are selected through assessment of significant cycle metrics to identify the ones with smallest errors. This paper provides a framework for synthesis of representative drive cycles from naturalistic driving data, which can subsequently be used for efficient optimization of design or control of pick-up truck powertrains. Manufacturers will benefit from representative drive cycles in several aspects, including quick assessments of vehicle performance and energy consumption in simulations, component sizing and design, optimization of control strategies, and

Predictions of fast wave heating, current drive, and current drive antenna arrays for advanced tokamaks

International Nuclear Information System (INIS)

Batchelor, D.B.; Baity, F.W.; Carter, M.D.

1994-01-01

The objective of the advanced tokamak program is to optimize plasma performance leading to a compact tokamak reactor through active, steady state control of the current profile using non-inductive current drive and profile control. To achieve these objectives requires compatibility and flexibility in the use of available heating and current drive systems--ion cyclotron radio frequency (ICRF), neutral beams, and lower hybrid. For any advanced tokamak, the following are important challenges to effective use of fast waves in various roles of direct electron heating, minority ion heating, and current drive: (1) to employ the heating and current drive systems to give self-consistent pressure and current profiles leading to the desired advanced tokamak operating modes; (2) to minimize absorption of the fast waves by parasitic resonances, which limit current drive; (3) to optimize and control the spectrum of fast waves launched by the antenna array for the required mix of simultaneous heating and current drive. The authors have addressed these issues using theoretical and computational tools developed at a number of institutions by benchmarking the computations against available experimental data and applying them to the specific case of TPX

Comparative Investigation on 0.4 inch SBLOCA Scenario with Single and Dual Train Passive Safety Injection Systems using SMART-ITL

Energy Technology Data Exchange (ETDEWEB)

Park, Hyun-Sik; Bae, Hwang; Ryu, Sung-Uk; Jeon, Byong-Guk; Yang, Jin-Hwa; Yun, Eun-Koo; Choi, Nam-Hyun; Min, Kyoung-Ho; Shin, Yong-Cheol; Bang, Yoon-Gon; Kim, Myoung-Jun; Seo, Chan-Jong; Yi, Sung-Jae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

The Standard Design Approval (SDA) for SMART was certificated in 2012 at the Korea Atomic Energy Research Institute (KAERI). In December 2015, Saudi Arabia and Korea started conducting a three-year project of Pre-Project Engineering (PPE) to prepare a Preliminary Safety Analysis Report (PSAR) and to review the feasibility of constructing SMART reactors in Saudi Arabia. In addition, an Integral Test Loop for the SMART design (SMART-ITL, or FESTA) has been constructed and it finished its commissioning tests in 2012. Consequently, a set of Design Base Accident (DBA) scenarios have been simulated using SMART-ITL. In this paper, a comparative investigation was performed on 0.4 inch SBLOCA scenario with single and dual train passive safety injection systems using SMART-ITL. In this paper, the effect of the train number of PSIS on a SBLOCA scenario is investigated for a break size of 0.4 inch. The single and dual train tests show a similar trend in general but the injected water migrates slightly differently in the RV and is discharged through the break nozzle. The parameters of the RV pressure, RV water level, accumulated break mass, and injection flowrates from the CMT and SIT were compared. Compared with the single train test, the increased injection rates from the two trains of the PSIS during the dual train test raised the RV water level, ensuring the safety of the reactor core.

Electrohydraulic drive system with planetary superposed gears

Energy Technology Data Exchange (ETDEWEB)

Graetz, A.; Klimek, K.H.; Welz, H.

1989-01-01

To prevent drive problems in ploughs the drives must be designed in such a way as to compensate for asymmetries. If electromechanical drives are replaced by an electrohydraulic drive system with superposed planetary gears and hydrostatic torque reaction supports the following advantages occur: load-free acceleration, load equalisation between main and auxiliary drive, overload protection, and reduction of systems vibrations. 2 figs., 2 tabs.

On use of radial evanescence remain term in kinematic hardening

International Nuclear Information System (INIS)

Geyer, P.

1995-10-01

A fine modelling of the material' behaviour can be necessary to study the mechanical strength of nuclear power plant' components under cyclic loads. Ratchetting is one of the last phenomena for which numerical models have to be improved. We discuss in this paper on use of radial evanescence remain term in kinematic hardening to improve the description of ratchetting in biaxial loading tests. It's well known that Chaboche elastoplastic model with two non linear kinematic hardening variables initially proposed by Armstrong and Frederick, usually over-predicts accumulation of ratchetting strain. Burlet and Cailletaud proposed in 1987 a non linear kinematic rule with a radial evanescence remain term. The two models lead to identical formulation for proportional loadings. In the case of a biaxial loading test (primary+secondary loading), Burlet and Cailletaud model leads to accommodation, when Chaboche one's leads to ratchetting with a constant increment of strain. So we can have an under-estimate with the first model and an over-estimate with the second. An easy method to improve the description of ratchetting is to combine the two kinematic rules. Such an idea is already used by Delobelle in his model. With analytical results in the case of tension-torsion tests, we show in a first part of the paper, the interest of radial evanescence remain term in the non linear kinematic rule to describe ratchetting: we give the conditions to get adaptation, accommodation or ratchetting and the value of the strain increment in the last case. In the second part of the paper, we propose to modify the elastoplastic Chaboche model by coupling the two types of hardening by means of two scalar parameters which can be identified independently on biaxial loading tests. Identification of these two parameters returns to speculate on the directions of strain in order to adjust the ratchetting to experimental observations. We use the experimental results on the austenitic steel 316L at room