Non-linear Vacuum Phenomena in Non-commutative QED
Alvarez-Gaumé, Luís
2001-01-01
We show that the classic results of Schwinger on the exact propagation of particles in the background of constant field-strengths and plane waves can be readily extended to the case of non-commutative QED. It is shown that non-perturbative effects on constant backgrounds are the same as their commutative counterparts, provided the on-shell gauge invariant dynamics is referred to a non-perturbatively related space-time frame. For the case of the plane wave background, we find evidence of the effective extended nature of non-commutative particles, producing retarded and advanced effects in scattering. Besides the known `dipolar' character of non-commutative neutral particles, we find that charged particles are also effectively extended, but they behave instead as `half-dipoles'.
A novel post-arc current measuring equipment based on vacuum arc commutation and arc blow
Liao, Minfu; Ge, Guowei; Duan, Xiongying; Huang, Zhihui
2017-07-01
The paper proposes a novel post-arc current measuring equipment (NPACME), which is based on the vacuum arc commutation and magnetic arc blow. The NPACME is composed of the vacuum circuit breaker (VCB), shunt resistor, protective gap, high-precision current sensor and externally applied transverse magnetic field (ETMF). The prototype of the NPACME is designed and controlled by optical fiber communications. The vacuum arc commutation between the vacuum arc and the shunt resistor with ETMF is investigated. The test platform is established in the synthetic short-circuit test and the vacuum arc is observed by the high speed CMOS camera. The mathematic description of the vacuum arc commutation is obtained. Based on the current commutation characteristic, the parameters of the NPACME are optimized and the post-arc current is measured. The measuring result of the post-arc current is accurate with small interference and the post-arc charge is obtained. The experimental results verify that the NPACME is correct and accurate, which can be used to measure the post-arc characteristic in breaking test.
Elastic modulus of diamond-like carbon films prepared by pulsed vacuum arc
Schultrich, B.; Scheibe, H.-J.; Grandremy, G.; Schneider, D.; Siemroth, P.
1994-12-01
Amorphous carbon films have been prepared by special pulsed vacuum arc depositon methods allowing high currents up to 1 kA and more. The Young's modulus of these films has been determined with respect to various technological parameters. For these measurements a method based on the propagation of ultrasonic surface waves has been applied which has been specially designed for the investigation of thin films below one micrometer. Large changes of the elastic modulus, depending on the technology, have been observed, contrasting with the common understanding of invariability of the elastic behavior. Reflecting the large structural variations possible in amorphous carbon, the elastic modulus represents a suitable parameter for characterizing the carbon-carbon network. Furthermore, the elastic modulus of amorphous carbon films may be used for a first estimation of film hardness because of the strong correlation of these two quantities.
Fontana, Marco; Olberding, Bruce; Swanson, Irena
2011-01-01
Commutative algebra is a rapidly growing subject that is developing in many different directions. This volume presents several of the most recent results from various areas related to both Noetherian and non-Noetherian commutative algebra. This volume contains a collection of invited survey articles by some of the leading experts in the field. The authors of these chapters have been carefully selected for their important contributions to an area of commutative-algebraic research. Some topics presented in the volume include: generalizations of cyclic modules, zero divisor graphs, class semigrou
van Ommeren, J.N.; Rietveld, P.
2005-01-01
We examine the conditions for the 'commuting time paradox' which states that the average commuting time does not vary between different periods. We develop therefore an equilibrium job search model with endogenously chosen commuting costs. Presuming wage bargaining between workers and firms, the
DEFF Research Database (Denmark)
Mulalic, Ismir; Ommeren, Jos N. van; Pilegaard, Ninette
2011-01-01
We examine the causal effect of commuting distance on workers' wages in a quasi-natural experiments setting using information on all workers in Denmark. We account for endogeneity of distance by using changes in distance that are due to firms’ relocations. For the range of commuting distances whe...
Directory of Open Access Journals (Sweden)
S. Castellani
2014-10-01
Full Text Available Local governments are seeking effective ways to promote sustainable commuting for reducing energy consumption and improving commuters’ experience. They often use so-called “Workplace Travel Plans” as policy interventions to engage work organizations as active players, promoting sustainable commuting amongst their employees. However, it remains difficult to systematically engage work organizations and commuters in such efforts for a number of reasons, ranging from preferences to constraints that they have to deal with. We aim at providing commuters, work organizations, and public administrators with tools that facilitate this engagement. In this paper, we discuss the requirements for the design of technology supporting corresponding services for commuters and work organizations and we shortly illustrate the infrastructure that we are developing to provide such services.
US Agency for International Development — This dataset is the USAID portion of a larger dataset developed by OMB to better understand and to quanity the carbon footprint of the daily commute of government...
DEFF Research Database (Denmark)
Mulalic, Ismir; Ommeren, Jos N. van; Pilegaard, Ninette
2011-01-01
We examine the causal effect of commuting distance on workers' wages in a quasi-natural experiments setting using information on all workers in Denmark. We account for endogeneity of distance by using changes in distance that are due to firms’ relocations. For the range of commuting distances where...... income tax reductions associated with commuting do not apply, one kilometre increase in commuting distance induces a wage increase of about 0.42%, suggesting an hourly compensation of about half of the hourly net wage. Our findings are consistent with wage bargaining theory and suggest a bargaining power...... parameter of about 0.50. Due to the experimental setup we are able to exclude many competing explanations of the wage-distance relationship....
Computational commutative and non-commutative algebraic geometry
Cojocaru, S; Ufnarovski, V
2005-01-01
This publication gives a good insight in the interplay between commutative and non-commutative algebraic geometry. The theoretical and computational aspects are the central theme in this study. The topic is looked at from different perspectives in over 20 lecture reports. It emphasizes the current trends in commutative and non-commutative algebraic geometry and algebra. The contributors to this publication present the most recent and state-of-the-art progresses which reflect the topic discussed in this publication. Both researchers and graduate students will find this book a good source of information on commutative and non-commutative algebraic geometry.
DEFF Research Database (Denmark)
Larsen, Jonas
2018-01-01
The uniqueness of this article is that it deals with long-distance bike commuting in pro-cycling Copenhagen and its environs. Informed by practice theory and sensuous studies of urban and sport practices, I discuss the ‘things and environments’, ‘meanings’ and ‘competences and biological bodies......’ that typify long-distance commuter cycling. This article develops cycling literature and the ‘mobilities paradigm’ in the following ways: by outlining a practice approach to cycling; challenging the idea that commuter cycling is only for short distances; undermining the distinction between utility and sport...... cycling; and lastly by connecting the ‘mobilities paradigm’ with literature on active travel and sport studies....
Jorgensen, Palle
2017-01-01
The book features new directions in analysis, with an emphasis on Hilbert space, mathematical physics, and stochastic processes. We interpret 'non-commutative analysis' broadly to include representations of non-Abelian groups, and non-Abelian algebras; emphasis on Lie groups and operator algebras (C* algebras and von Neumann algebras.)A second theme is commutative and non-commutative harmonic analysis, spectral theory, operator theory and their applications. The list of topics includes shift invariant spaces, group action in differential geometry, and frame theory (over-complete bases) and their applications to engineering (signal processing and multiplexing), projective multi-resolutions, and free probability algebras.The book serves as an accessible introduction, offering a timeless presentation, attractive and accessible to students, both in mathematics and in neighboring fields.
Combinatorial commutative algebra
Miller, Ezra
2005-01-01
Offers an introduction to combinatorial commutative algebra, focusing on combinatorial techniques for multigraded polynomial rings, semigroup algebras, and determined rings. The chapters in this work cover topics ranging from homological invariants of monomial ideals and their polyhedral resolutions, to tools for studying algebraic varieties.
Commutation and Darboux transformation
Indian Academy of Sciences (India)
2015-10-20
Oct 20, 2015 ... http://www.ias.ac.in/article/fulltext/pram/085/05/0869-0880. Keywords. Darboux transformation; nonlinear evolution equations; exact solutions. Abstract. In this paper we show that the Darboux transformation for a large class of nonlinear evolution equations arises due to factorization and commutation.
Commutation relations of operator monomials
Pain, Jean-Christophe
2013-01-01
In this short paper, the commutator of monomials of operators obeying constant commutation relations is expressed in terms of anti-commutators. The formula involves Bernoulli numbers or Euler polynomials evaluated in zero. The role of Bernoulli numbers in quantum-mechanical identities such as the Baker-Campbell-Hausdorff formula is emphasized and applications connected to ordering problems as well as to the Ehrenfest theorem are proposed.
Radar channel balancing with commutation
Energy Technology Data Exchange (ETDEWEB)
Doerry, Armin Walter
2014-02-01
When multiple channels are employed in a pulse-Doppler radar, achieving and maintaining balance between the channels is problematic. In some circumstances the channels may be commutated to achieve adequate balance. Commutation is the switching, trading, toggling, or multiplexing of the channels between signal paths. Commutation allows modulating the imbalance energy away from the balanced energy in Doppler, where it can be mitigated with filtering.
Gorter, C.; Berg, van den G.J.
1996-01-01
We structurally analyze a job search model for unemployed individuals that allows jobs to have different wage/commuting-time combinations. Thestructural parameter of interest is the willingness to pay for commuting time. We use a unique dataset containing subjective responses on the optimalsearch
Challenges in Computational Commutative Algebra
Abbott, John
2006-01-01
In this paper we consider a number of challenges from the point of view of the CoCoA project one of whose tasks is to develop software specialized for computations in commutative algebra. Some of the challenges extend considerably beyond the boundary of commutative algebra, and are addressed to the computer algebra community as a whole.
Rouwendal, J.; van der Vlist, A.J.
2005-01-01
This paper studies the interaction between commuting, job mobility, and housing mobility. Manny conventional models assume that the employment location has priority over the residential location and that the latter is adapted to the former. This implies that commutes which start with a job change
Rouwendal, J.; Vlist, van der A.J.
2005-01-01
This paper studies the interaction between commuting, job mobility, and housing mobility. Many conventional models assume that the employment location has priority over the residential location and that the latter is adapted to the former. This implies that commutes which start with a job change
-commuting maps and invariant approximations
Directory of Open Access Journals (Sweden)
Rhoades BE
2006-01-01
Full Text Available We obtain common fixed point results for generalized -nonexpansive -commuting maps. As applications, various best approximation results for this class of maps are derived in the setup of certain metrizable topological vector spaces.
Computational linear and commutative algebra
Kreuzer, Martin
2016-01-01
This book combines, in a novel and general way, an extensive development of the theory of families of commuting matrices with applications to zero-dimensional commutative rings, primary decompositions and polynomial system solving. It integrates the Linear Algebra of the Third Millennium, developed exclusively here, with classical algorithmic and algebraic techniques. Even the experienced reader will be pleasantly surprised to discover new and unexpected aspects in a variety of subjects including eigenvalues and eigenspaces of linear maps, joint eigenspaces of commuting families of endomorphisms, multiplication maps of zero-dimensional affine algebras, computation of primary decompositions and maximal ideals, and solution of polynomial systems. This book completes a trilogy initiated by the uncharacteristically witty books Computational Commutative Algebra 1 and 2 by the same authors. The material treated here is not available in book form, and much of it is not available at all. The authors continue to prese...
MIT employee commuter behavior trial.
2013-04-01
The objectives of the project included the following: : To evaluate the potential impact (in terms of commuter mode shifts) from the introduction of : disruptive technologies at the Massachusetts Institute of Technology in Cambridge, MA, includin...
Directory of Open Access Journals (Sweden)
Shervin Sahebi
2014-05-01
Full Text Available $R$ is called commuting regular ring (resp. semigroupif for each $x,y\\in R$ there exists $a\\in R$ such that$xy=yxayx$. In this paper, we introduce the concept ofcommuting $\\pi$-regular rings (resp. semigroups andstudy various properties of them.
Commuting projections on graphs
Energy Technology Data Exchange (ETDEWEB)
Vassilevski, Panayot S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Center for Applied Scientific Computing; Zikatanov, Ludmil T. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Mathematics
2013-02-19
For a given (connected) graph, we consider vector spaces of (discrete) functions defined on its vertices and its edges. These two spaces are related by a discrete gradient operator, Grad and its adjoint, ₋Div, referred to as (negative) discrete divergence. We also consider a coarse graph obtained by aggregation of vertices of the original one. Then a coarse vertex space is identified with the subspace of piecewise constant functions over the aggregates. We consider the ℓ_{2}-projection Q_{H} onto the space of these piecewise constants. In the present paper, our main result is the construction of a projection π _{H} from the original edge-space onto a properly constructed coarse edge-space associated with the edges of the coarse graph. The projections π _{H} and Q_{H} commute with the discrete divergence operator, i.e., we have div π _{H} = Q_{H} div. The respective pair of coarse edge-space and coarse vertexspace offer the potential to construct two-level, and by recursion, multilevel methods for the mixed formulation of the graph Laplacian which utilizes the discrete divergence operator. The performance of one two-level method with overlapping Schwarz smoothing and correction based on the constructed coarse spaces for solving such mixed graph Laplacian systems is illustrated on a number of graph examples.
Eichmeier, Joseph A
2008-01-01
Nineteen experts from the electronics industry, research institutes and universities have joined forces to prepare this book. ""Vacuum Electronics"" covers the electrophysical fundamentals, the present state of the art and applications, as well as the future prospects of microwave tubes and systems, optoelectronics vacuum devices, electron and ion beam devices, light and X-ray emitters, particle accelerators and vacuum interrupters. These topics are supplemented by useful information about the materials and technologies of vacuum electronics and vacuum technology.
A Note on UV/IR Mixing and Non-Commutative Instanton Calculus
Bichl, A A
2003-01-01
We estimate the instanton-induced vacuum energy in non-commutative U(1) Yang-Mills theory in four dimensions. In the dilute gas approximation, it is found to be plagued by infrared divergences, as a result of UV/IR mixing.
A New Approach of Minimizing Commutation Torque Ripple for BLDCM
Directory of Open Access Journals (Sweden)
Bo Tan
2017-10-01
Full Text Available The properties of brushless DC motor (BLDCM are similar to the fractional, slot-concentrated winding of permanent-magnet synchronous machines, and they fit well for electric vehicle application. However, BLDCM still suffers from the high commutation torque ripple in the case of the traditional square-wave current control (SWC method, where the current vector rotates asynchronously with back-EMF. A current optimizing control (COC method for BLDCM is proposed in the paper to minimize the commutation torque ripple. The trajectories of the three phase currents are planned by the given torque and the optimized result of the copper loss and motor torque equations. The properties of COC are analyzed and compared with that of SWC in the stationary reference frame. The results show that the way of making the current vector rotate synchronously with back-EMF (back-Electromotive Force can minimize the modulus and velocity of the current vector in the commutation region, and reduce the torque ripple. Experimental tests obtained from an 82 W BLDCM are done to confirm the theoretical findings.
DEFF Research Database (Denmark)
Maagaard, Mathilde; Oestergaard, Jeanett; Johansen, Marianne
2012-01-01
Objectives. To develop and validate an Objective Structured Assessment of Technical Skills (OSATS) scale for vacuum extraction. Design. Two part study design: Primarily, development of a procedure-specific checklist for vacuum extraction. Hereafter, validationof the developed OSATS scale for vacuum...
Commuting in the settlement system of Serbia
Directory of Open Access Journals (Sweden)
Lukić Vesna
2011-01-01
Full Text Available Territorial organization of settlement system is the framework for internal migration flows. The purpose of this paper is to consider the relation between commuting and the settlement structure. Commuting patterns and characteristics of commuters in Serbia are relatively unknown and insufficiently researched, and as such, can not be adequately used in creation of development strategies and public policies which would include commuters' issues. It has been emphasized the importance of research of commuting ties between different settlements and also pointed out in which way commuting flows could be researched and analyzed by using existing sources, due to better understanding of connections between migrations and settlements. Commuting patterns of workers in Serbia and interrelations between the scope and the structure of commuting flows, as well as the type and population size of settlements in Serbia have been examined. Apart from territorial dimension of commuting phenomenon, socio-economic component of commuting population has also been considered. The use of costumised tabulations from 2002 Census have enabled us to examine all types of commuting and emphasise dominant directions of commuting flows of economically active population according to gender, level of education and sector of economic activity, within the settlement hierarchy. Workers have been classified into seven groups according to place of residence and place of work. The findings reveal there is a clear connection between the hierarchy structure and commuting patterns in Serbia. Further, we find some evidence that only 9,5% of workers - commuters have been working in the settlement of the same population size and type such as their residing settlement. Commuting flows within Serbia’s settlement system point out to certain variations when looking at individual categories of population, but it can be concluded that there is general trend of commuting "upwards" within the
Non-Commutativity and the Theta Term
Obregón, O.; Santos-Silva, R.
2014-11-01
In the presente paper we will study the non-commutativity in the space-time through the map developed by N. Seiberg and E. Witten, and explore the topological implications due to the introduction of non-commutativity. We will explore this topological properties using a non-commutative extension of the θ-term (second Chern class) on the 4dimensional sphere.
8 CFR 211.5 - Alien commuters.
2010-01-01
... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Alien commuters. 211.5 Section 211.5 Aliens...: IMMIGRANTS; WAIVERS § 211.5 Alien commuters. (a) General. An alien lawfully admitted for permanent residence.... An alien commuter engaged in seasonal work will be presumed to have taken up residence in the United...
Determination of Young's Modulus of Graphene by Raman Spectroscopy
Lee, Jae-Ung; Yoon, Duhee; Cheong, Hyeonsik
2012-02-01
The mechanical properties of graphene are interesting research subjects because its Young's modulus and strength are extremely high. Values of ˜1 TPa for the Young's modulus have been reported [Lee et al. Science, 321, 385 (2008), Koenig et al. Nat. Nanotech. 6, 543 (2011)]. We made a graphene sample on a SiO2/Si substrate with closed-bottom holes by mechanical exfoliation. A pressure difference across the graphene membrane was applied by putting the sample in a vacuum chamber. This pressure difference makes the graphene membrane bulge upward like a balloon. By measuring the shifts of the Raman G and 2D bands, we estimated the amount of strain on the graphene membrane. By comparing the strain estimated from the Raman measurements with numerical simulations based on the finite element method, we obtained the Young's modulus of graphene.
On CNC commuting contractive tuples
Indian Academy of Sciences (India)
The characteristic function has been an important tool for studying completely non-unitary contractions on Hilbert spaces. In this note, we consider completely non-coisometric contractive tuples of commuting operators on a Hilbert space H . We show that the characteristic function, which is now an operator-valued analytic ...
On commuting operator exponentials, II
Indian Academy of Sciences (India)
Home; Journals; Proceedings – Mathematical Sciences; Volume 123; Issue 1. On Commuting Operator Exponentials, II. Fotios C Paliogiannis. Volume 123 Issue 1 February 2013 pp 27-31. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/pmsc/123/01/0027-0031. Keywords.
On commuting operator exponentials, II
Indian Academy of Sciences (India)
p. 268 of. [8]). In the present paper we are concerned with the reverse implication, when A and B are normal operators. Commuting exponentials of bounded normal operators have been studied in [4], [5] and [9]. Here, we extend these results to ...
Magnitude control of commutator errors
Geurts, Bernardus J.; Wesseling, P.; Oñate, E.; Périaux, J.
2006-01-01
Non-uniform filtering of the Navier-Stokes equations expresses itself, next to the turbulent stresses, in additional closure terms known as commutator errors. These terms require explicit subgrid modeling if the non-uniformity of the filter is sufficiently pronounced. We derive expressions for the
Workers' marginal costs of commuting
DEFF Research Database (Denmark)
van Ommeren, Jos; Fosgerau, Mogens
2009-01-01
This paper applies a dynamic search model to estimate workers' marginal costs of commuting, including monetary and time costs. Using data on workers' job search activity as well as moving behaviour, for the Netherlands, we provide evidence that, on average, workers' marginal costs of one hour of ...
Search Theory and Commuting Behaviour
Rouwendal, J.
2004-01-01
This paper argues that search theory is a useful addition to the way economists and geographers have approached the study of commuting behavior. This is illustrated by showing that introduction of a spatial element into the standard model of job search leads to the prediction of critical isochrones.
Non-commutativity in polar coordinates
Energy Technology Data Exchange (ETDEWEB)
Edwards, James P. [Universidad Michoacana de San Nicolas de Hidalgo, Ciudad Universitaria, Instituto de Fisica y Matematicas, Morelia, Michoacan (Mexico)
2017-05-15
We reconsider the fundamental commutation relations for non-commutative R{sup 2} described in polar coordinates with non-commutativity parameter θ. Previous analysis found that the natural transition from Cartesian coordinates to the traditional polar system led to a representation of [r, φ] as an everywhere diverging series. In this article we compute the Borel resummation of this series, showing that it can subsequently be extended throughout parameter space and hence provide an interpretation of this commutator. Our analysis provides a complete solution for arbitrary r and θ that reproduces the earlier calculations at lowest order and benefits from being generally applicable to problems in a two-dimensional non-commutative space. We compare our results to previous literature in the (pseudo-)commuting limit, finding a surprising spatial dependence for the coordinate commutator when θ >> r{sup 2}. Finally, we raise some questions for future study in light of this progress. (orig.)
Gordon, H.S.
1959-09-15
An improved adsorption vacuum trap for use in vacuum systems was designed. The distinguishing feature is the placement of a plurality of torsionally deformed metallic fins within a vacuum jacket extending from the walls to the central axis so that substantially all gas molecules pass through the jacket will impinge upon the fin surfaces. T fins are heated by direct metallic conduction, thereby ol taining a uniform temperature at the adeorbing surfaces so that essentially all of the condensible impurities from the evacuating gas are removed from the vacuum system.
Energy Technology Data Exchange (ETDEWEB)
Biltoft, P J
2004-10-15
The environmental condition called vacuum is created any time the pressure of a gas is reduced compared to atmospheric pressure. On earth we typically create a vacuum by connecting a pump capable of moving gas to a relatively leak free vessel. Through operation of the gas pump the number of gas molecules per unit volume is decreased within the vessel. As soon as one creates a vacuum natural forces (in this case entropy) work to restore equilibrium pressure; the practical effect of this is that gas molecules attempt to enter the evacuated space by any means possible. It is useful to think of vacuum in terms of a gas at a pressure below atmospheric pressure. In even the best vacuum vessels ever created there are approximately 3,500,000 molecules of gas per cubic meter of volume remaining inside the vessel. The lowest pressure environment known is in interstellar space where there are approximately four molecules of gas per cubic meter. Researchers are currently developing vacuum technology components (pumps, gauges, valves, etc.) using micro electro mechanical systems (MEMS) technology. Miniature vacuum components and systems will open the possibility for significant savings in energy cost and will open the doors to advances in electronics, manufacturing and semiconductor fabrication. In conclusion, an understanding of the basic principles of vacuum technology as presented in this summary is essential for the successful execution of all projects that involve vacuum technology. Using the principles described above, a practitioner of vacuum technology can design a vacuum system that will achieve the project requirements.
Hackwood, Susan; Belinski, Steven E.; Beni, Gerardo
1989-01-01
The discipline of vacuum mechatronics is defined as the design and development of vacuum-compatible computer-controlled mechanisms for manipulating, sensing and testing in a vacuum environment. The importance of vacuum mechatronics is growing with an increased application of vacuum in space studies and in manufacturing for material processing, medicine, microelectronics, emission studies, lyophylisation, freeze drying and packaging. The quickly developing field of vacuum mechatronics will also be the driving force for the realization of an advanced era of totally enclosed clean manufacturing cells. High technology manufacturing has increasingly demanding requirements for precision manipulation, in situ process monitoring and contamination-free environments. To remove the contamination problems associated with human workers, the tendency in many manufacturing processes is to move towards total automation. This will become a requirement in the near future for e.g., microelectronics manufacturing. Automation in ultra-clean manufacturing environments is evolving into the concept of self-contained and fully enclosed manufacturing. A Self Contained Automated Robotic Factory (SCARF) is being developed as a flexible research facility for totally enclosed manufacturing. The construction and successful operation of a SCARF will provide a novel, flexible, self-contained, clean, vacuum manufacturing environment. SCARF also requires very high reliability and intelligent control. The trends in vacuum mechatronics and some of the key research issues are reviewed.
Standard test method for Young's modulus, tangent modulus, and chord modulus
American Society for Testing and Materials. Philadelphia
2004-01-01
1.1 This test method covers the determination of Young's modulus, tangent modulus, and chord modulus of structural materials. This test method is limited to materials in which and to temperatures and stresses at which creep is negligible compared to the strain produced immediately upon loading and to elastic behavior. 1.2 Because of experimental problems associated with the establishment of the origin of the stress-strain curve described in 8.1, the determination of the initial tangent modulus (that is, the slope of the stress-strain curve at the origin) and the secant modulus are outside the scope of this test method. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory require...
On the interrelations between migration and commuting
Lukić Vesna
2013-01-01
In this paper, we emphasise the significance of studying the interrelations between commuting and migration. The aim of the paper is to point out the factors which affect these interrelations (demographic and socio-economic characteristics of migrants and commuters, labour market, real estate market, information, life style, etc.), with the special emphasis on the role of commuting distance onto the chosen mobility type. Besides theorethical frameworks and results of the selected foreig...
Partially-commutative context-free languages
Sławomir Lasota; Wojciech Czerwiński
2012-01-01
The paper is about a class of languages that extends context-free languages (CFL) and is stable under shuffle. Specifically, we investigate the class of partially-commutative context-free languages (PCCFL), where non-terminal symbols are commutative according to a binary independence relation, very much like in trace theory. The class has been recently proposed as a robust class subsuming CFL and commutative CFL. This paper surveys properties of PCCFL. We identify a natural corresponding auto...
Limits of Commutativity on Abstract Data Types
Malta, Carmelo; Martinez, José
1992-01-01
International audience; We present some formal properties of (symmetrical) commutativity, the major criterion used in transactional systems, which allow us to fully understand its advantages and disadvantages. The main result is that commutativity is subject to the same limitation as compatibility for arbitrary objects. However, commutativity has also a number of attracting properties, one of which is related to recovery and, to our knowledge, has not been exploited in the literature. Advanta...
Modulus optimum for digital controllers
Directory of Open Access Journals (Sweden)
Víteèek Antonín
2003-12-01
Full Text Available The paper extends the popular modulus optimum with the original approach for the conventional digital controllers. The use of the D-transform allows obtaining the uniform computing formulas for the values of the digital and analog controller tuning parameters. The use is shown on an example.
Commutation failure at restart of an inverter
Energy Technology Data Exchange (ETDEWEB)
Bruntt, M.
1997-12-31
The sensitivity of commutation failures for an HVDC inverter due to AC voltage magnitude reduction and AC voltage distortion depends on the specific HVDC main circuit design and on the HVDC control system. There are ways to improve the immunity towards commutation failures, but they can never be completely avoided. This report deals with commutation failures at restart of an inverter, and does not consider the initial commutation failure. If the AC system after the fault is capable of absorbing the power from the restarting HVDC link without disturbing the AC voltage significantly, the HVDC link is back to normal operation after typically 50 to 200 ms after the fault is cleared. The stability of the connected AC systems is not seriously affected by this limited time period with lack or excess of power. This report deals with the idea of finding an indicator for the second commutation failure during restart. The process of commutation failures and furthermore commutation failures during restart are characterized. A network which is considered to be general is analysed to find indication of commutation failure during restart. Different potential indictors are examined. The effect of changing the general control parameters during the restart to help the recovery in critical situations is also examined. The analysis do, however, not give the answer to which parameters are the best to change because this question need to be answered for each specific case. Finally a specific network is analysed to find an indicator of a second commutation failure. (EG)
Active Commuting to School as a Source of Health Promotion ...
African Journals Online (AJOL)
The students were predominantly passive commuters and their commuting pattern was linked to sociodemographic characteristics while barriers and facilitators of active commuting included family, societal, environmental and school factors. KEYWORDS: adolescents health, attitudes, physical activity, sociodemographic ...
Robles-Pérez, Salvador
2017-11-01
We apply the Lewis-Riesenfeld invariant method for the harmonic oscillator with time dependent mass and frequency to the modes of a charged scalar field that propagates in a curved, homogeneous and isotropic spacetime. We recover the Bunch-Davies vacuum in the case of a flat DeSitter spacetime, the equivalent one in the case of a closed DeSitter spacetime and the invariant vacuum in a curved spacetime that evolves adiabatically. In the three cases, it is computed the thermodynamical magnitudes of entanglement between the modes of the particles and antiparticles of the invariant vacuum, and the modification of the Friedmann equation caused by the existence of the energy density of entanglement. The amplitude of the vacuum fluctuations are also computed.
Energy Technology Data Exchange (ETDEWEB)
Chernin, Artur D [P.K. Shternberg State Astronomical Institute at the M.V. Lomonosov Moscow State University, Moscow (Russian Federation)
2001-11-30
Recent observational studies of distant supernovae have suggested the existence of cosmic vacuum whose energy density exceeds the total density of all the other energy components in the Universe. The vacuum produces the field of antigravity that causes the cosmological expansion to accelerate. It is this accelerated expansion that has been discovered in the observations. The discovery of cosmic vacuum radically changes our current understanding of the present state of the Universe. It also poses new challenges to both cosmology and fundamental physics. Why is the density of vacuum what it is? Why do the densities of the cosmic energy components differ in exact value but agree in order of magnitude? On the other hand, the discovery made at large cosmological distances of hundreds and thousands Mpc provides new insights into the dynamics of the nearby Universe, the motions of galaxies in the local volume of 10 - 20 Mpc where the cosmological expansion was originally discovered. (reviews of topical problems)
Franchetti, G
2013-01-01
This paper continues the presentation of pumps begun in ‘Vacuum I’. The main topic here is gauges and partial-pressure measurements. Starting from the kinetics of gases, the various strategies for measuring vacuum pressures are presented at an introductory level, with some reference to hardware devices. Partial-pressure measurement techniques are introduced, showing that the principles of ion selection have a direct similarity to particle dynamics in accelerators.
Ultrasonic metamaterials with negative modulus.
Fang, Nicholas; Xi, Dongjuan; Xu, Jianyi; Ambati, Muralidhar; Srituravanich, Werayut; Sun, Cheng; Zhang, Xiang
2006-06-01
The emergence of artificially designed subwavelength electromagnetic materials, denoted metamaterials, has significantly broadened the range of material responses found in nature. However, the acoustic analogue to electromagnetic metamaterials has, so far, not been investigated. We report a new class of ultrasonic metamaterials consisting of an array of subwavelength Helmholtz resonators with designed acoustic inductance and capacitance. These materials have an effective dynamic modulus with negative values near the resonance frequency. As a result, these ultrasonic metamaterials can convey acoustic waves with a group velocity antiparallel to phase velocity, as observed experimentally. On the basis of homogenized-media theory, we calculated the dispersion and transmission, which agrees well with experiments near 30 kHz. As the negative dynamic modulus leads to a richness of surface states with very large wavevectors, this new class of acoustic metamaterials may offer interesting applications, such as acoustic negative refraction and superlensing below the diffraction limit.
Elastic modulus of hard tissues.
Bar-On, Benny; Wagner, H Daniel
2012-02-23
This work aims at evaluating the elastic modulus of hard biological tissues by considering their staggered platelet micro-structure. An analytical expression for the effective modulus along the stagger direction is formulated using three non-dimensional structural variables. Structures with a single staggered hierarchy (e.g. collagen fibril) are first studied and predictions are compared with the experimental results and finite element simulations from the literature. A more complicated configuration, such as an array of fibrils, is analyzed next. Finally, a mechanical model is proposed for tooth dentin, in which variations in the multi-scale structural hierarchy are shown to significantly affect the macroscopic mechanical properties. Copyright © 2011 Elsevier Ltd. All rights reserved.
Factors affecting commuter rail energy efficiency.
2016-02-17
The objective of this study is to develop a planninglevel model of commuter rail energy efficiency. The : environmental benefits of commuter rail are often cited as one of the key benefits and motivators for its rapid development as a public trans...
Modulus stabilization in a non-flat warped braneworld scenario
Energy Technology Data Exchange (ETDEWEB)
Banerjee, Indrani [S.N. Bose National Centre for Basic Sciences, Department of Astrophysics and Cosmology, Kolkata (India); SenGupta, Soumitra [Indian Association for the Cultivation of Science, Department of Theoretical Physics, Kolkata (India)
2017-05-15
The stability of the modular field in a warped brane world scenario has been a subject of interest for a long time. Goldberger and Wise (GW) proposed a mechanism to achieve this by invoking a massive scalar field in the bulk space-time neglecting the back-reaction. In this work, we examine the possibility of stabilizing the modulus without bringing about any external scalar field. We show that instead of flat 3-branes as considered in Randall-Sundrum (RS) warped braneworld model, if one considers a more generalized version of warped geometry with de Sitter 3-brane, then the brane vacuum energy automatically leads to a modulus potential with a metastable minimum. Our result further reveals that in this scenario the gauge hierarchy problem can also be resolved for an appropriate choice of the brane's cosmological constant. (orig.)
Chng, Samuel; White, Mathew; Abraham, Charles; Skippon, Stephen
2016-07-01
To explore the relationships between commute mode, neighbourhood public transport connectivity and subjective wellbeing. The study used data on 3630 commuters in London from wave two of Understanding Society (2010/11). Multivariate linear regressions were used to investigate how commute mode and neighbourhood public transport connectivity were associated with subjective wellbeing for all London commuters and for public transport commuters only. Subjective wellbeing was operationalized in terms of both a positive expression (life satisfaction measured by a global single-item question) and a more negative expression (mental distress measured by the General Health Questionnaire). Logistic regression was also used to explore the predictors of public transport over non-public transport commutes. After accounting for potentially-confounding area-level and individual-level socioeconomic and commute-related variables, only walking commutes (but not other modes) were associated with significantly higher life satisfaction than car use but not with lower mental distress, compared to driving. While better public transport connectivity was associated with significantly lower mental distress in general, train users with better connectivity had higher levels of mental distress. Moreover, connectivity was unrelated to likelihood of using public transport for commuting. Instead, public transport commutes were more likely amongst younger commuters who made longer distance commutes and had comparatively fewer children and cars within the household. The findings highlight the heterogeneity of relationships between commute mode, public transport connectivity and subjective wellbeing and have implications for intervention strategies and policies designed to promote commuting behaviour change. Copyright © 2016 Elsevier Inc. All rights reserved.
Fertility and Commuting Behaviour in Germany
Directory of Open Access Journals (Sweden)
Johannes Huinink
2012-12-01
Firstly, a cross-sectional, multivariate probit-regression (with correlated errors on the intention to have a child within two years, on being childless and on medium- and long- distance commuting is applied. The model shows no significant correlation between commuting and the intention to have a child; it does however show a correlation between medium- and long distance commuting and the probability of women to be childless. Secondly, a longitudinal difference model on changing fertility intentions between panel wave 1 and wave 3 is estimated. For women, a positive effect can be found of interrupting medium- and long-distance commuting or, surprisingly, continuing medium- and long-distance commuting on the intention to have a child within two years. Thirdly, for men and women who reported a fertility intention in the first wave, a longitudinal Heckman-selection probit-regression on the probability of having a child between wave 1 and wave 3 is estimated. It shows negative effects of medium- and long-distance commuting on having a child. Taken together, these findings support the assumption that commuting plays a characteristically different role in different phases of the fertility-related decision process.
Fostering Formal Commutativity Knowledge with Approximate Arithmetic.
Directory of Open Access Journals (Sweden)
Sonja Maria Hansen
Full Text Available How can we enhance the understanding of abstract mathematical principles in elementary school? Different studies found out that nonsymbolic estimation could foster subsequent exact number processing and simple arithmetic. Taking the commutativity principle as a test case, we investigated if the approximate calculation of symbolic commutative quantities can also alter the access to procedural and conceptual knowledge of a more abstract arithmetic principle. Experiment 1 tested first graders who had not been instructed about commutativity in school yet. Approximate calculation with symbolic quantities positively influenced the use of commutativity-based shortcuts in formal arithmetic. We replicated this finding with older first graders (Experiment 2 and third graders (Experiment 3. Despite the positive effect of approximation on the spontaneous application of commutativity-based shortcuts in arithmetic problems, we found no comparable impact on the application of conceptual knowledge of the commutativity principle. Overall, our results show that the usage of a specific arithmetic principle can benefit from approximation. However, the findings also suggest that the correct use of certain procedures does not always imply conceptual understanding. Rather, the conceptual understanding of commutativity seems to lag behind procedural proficiency during elementary school.
1974-01-01
This valve was used in the Intersecting Storage Rings (ISR) to protect against the shock waves that would be caused if air were to enter the vacuum tube. Some of the ISR chambers were very fragile, with very thin walls - a design required by physicists on the lookout for new particles.
Exploratory mapping of commuter flows in England and Wales
DEFF Research Database (Denmark)
Nielsen, Thomas Alexander Sick; Harder, Henrik
2008-01-01
The paper uses the origin–destination commute data published from the 1991 and 2001 Census to explore the developments in commuting and interaction patterns within England and Wales. Focus is on the geographical variations and a map of commuter flows is presented. Commuting is stretched out along...
The theory of finitely generated commutative semigroups
Rédei, L; Stark, M; Gravett, K A H
1966-01-01
The Theory of Finitely Generated Commutative Semigroups describes a theory of finitely generated commutative semigroups which is founded essentially on a single """"fundamental theorem"""" and exhibits resemblance in many respects to the algebraic theory of numbers. The theory primarily involves the investigation of the F-congruences (F is the the free semimodule of the rank n, where n is a given natural number). As applications, several important special cases are given. This volume is comprised of five chapters and begins with preliminaries on finitely generated commutative semigroups before
On the interrelations between migration and commuting
Directory of Open Access Journals (Sweden)
Lukić Vesna
2013-01-01
Full Text Available In this paper, we emphasise the significance of studying the interrelations between commuting and migration. The aim of the paper is to point out the factors which affect these interrelations (demographic and socio-economic characteristics of migrants and commuters, labour market, real estate market, information, life style, etc., with the special emphasis on the role of commuting distance onto the chosen mobility type. Besides theorethical frameworks and results of the selected foreign researches up to date, the overview of research of interrelations between migration and commuting in Serbia has also been presented. While earlier studies conducted by Gawryszenski (1978, Termote (1980 and Reitsma&Vergoossen (1987 pointed to the replacement of migration types between each other within country, in recent literature the interaction between migration and commuting has been studied in a trans-boundary context of the contemporary EU. Modern trend of long distance commuting instead of migration and the concept of substitution/replacement regarding migration and commuting have also been discussed. In Serbia, there is a positive correlation between commuting outflows and immigration in rural settlements of Vojvodina province. Namely, commuting and migration are complement, which is the characteristic of both processes sub-urbanisation and ex-urbanisation (Lukić, 2012. In addition to ownership of real estate and previous migration experience, marital status influenced the chosen mobility type in Serbia as well. Adjustment to changes of Serbian labour market is mostly conducted via migration (Miletić, Lukić, Miljanović, 2011. Interrelations between migration and commuting are very significant due to the tendency of transformation of some commuters into migrants. This process has its consequences, both on demographic as well as the overall socio-economic development of the area of commuters’ origin and destination. However, even though the surveys
Determinants of self-employment among commuters and non-commuters
DEFF Research Database (Denmark)
Backman, M.; Karlsson, C.
2016-01-01
We analyse the determinants of self-employment and focus on the contextual environment. By distinguishing between commuters and non-commuters we are able to analyse the influence from the work and home environment, respectively. Our results indicate a significant difference between non......-commuters and commuters in terms of the role of networks for becoming self-employed. Our results indicate that it is the business networks where people work, rather than where they live that exerts a positive influence on the probability of becoming self-employed. These effects are further robust over educational...
Foundations of commutative rings and their modules
Wang, Fanggui
2016-01-01
This book provides an introduction to the basics and recent developments of commutative algebra. A glance at the contents of the first five chapters shows that the topics covered are ones that usually are included in any commutative algebra text. However, the contents of this book differ significantly from most commutative algebra texts: namely, its treatment of the Dedekind–Mertens formula, the (small) finitistic dimension of a ring, Gorenstein rings, valuation overrings and the valuative dimension, and Nagata rings. Going further, Chapter 6 presents w-modules over commutative rings as they can be most commonly used by torsion theory and multiplicative ideal theory. Chapter 7 deals with multiplicative ideal theory over integral domains. Chapter 8 collects various results of the pullbacks, especially Milnor squares and D+M constructions, which are probably the most important example-generating machines. In Chapter 9, coherent rings with finite weak global dimensions are probed, and the local ring of weak gl...
Cq-commuting maps and invariant approximations
Directory of Open Access Journals (Sweden)
B. E. Rhoades
2006-06-01
Full Text Available We obtain common fixed point results for generalized I-nonexpansive Cq-commuting maps. As applications, various best approximation results for this class of maps are derived in the setup of certain metrizable topological vector spaces.
Covariant non-commutative space–time
Directory of Open Access Journals (Sweden)
Jonathan J. Heckman
2015-05-01
Full Text Available We introduce a covariant non-commutative deformation of 3+1-dimensional conformal field theory. The deformation introduces a short-distance scale ℓp, and thus breaks scale invariance, but preserves all space–time isometries. The non-commutative algebra is defined on space–times with non-zero constant curvature, i.e. dS4 or AdS4. The construction makes essential use of the representation of CFT tensor operators as polynomials in an auxiliary polarization tensor. The polarization tensor takes active part in the non-commutative algebra, which for dS4 takes the form of so(5,1, while for AdS4 it assembles into so(4,2. The structure of the non-commutative correlation functions hints that the deformed theory contains gravitational interactions and a Regge-like trajectory of higher spin excitations.
Partially-commutative context-free languages
Directory of Open Access Journals (Sweden)
Sławomir Lasota
2012-08-01
Full Text Available The paper is about a class of languages that extends context-free languages (CFL and is stable under shuffle. Specifically, we investigate the class of partially-commutative context-free languages (PCCFL, where non-terminal symbols are commutative according to a binary independence relation, very much like in trace theory. The class has been recently proposed as a robust class subsuming CFL and commutative CFL. This paper surveys properties of PCCFL. We identify a natural corresponding automaton model: stateless multi-pushdown automata. We show stability of the class under natural operations, including homomorphic images and shuffle. Finally, we relate expressiveness of PCCFL to two other relevant classes: CFL extended with shuffle and trace-closures of CFL. Among technical contributions of the paper are pumping lemmas, as an elegant completion of known pumping properties of regular languages, CFL and commutative CFL.
Developing a methodology for projecting intercity commuting.
2015-12-01
Texas agencies are investigating passenger rail options in several corridors connecting people : between the states major cities. Popular thinking is that there is commuter travel between a : number of these markets. In specific, Austin to Houston...
High elastic modulus polymer electrolytes
Balsara, Nitash Pervez; Singh, Mohit; Eitouni, Hany Basam; Gomez, Enrique Daniel
2013-10-22
A polymer that combines high ionic conductivity with the structural properties required for Li electrode stability is useful as a solid phase electrolyte for high energy density, high cycle life batteries that do not suffer from failures due to side reactions and dendrite growth on the Li electrodes, and other potential applications. The polymer electrolyte includes a linear block copolymer having a conductive linear polymer block with a molecular weight of at least 5000 Daltons, a structural linear polymer block with an elastic modulus in excess of 1.times.10.sup.7 Pa and an ionic conductivity of at least 1.times.10.sup.-5 Scm.sup.-1. The electrolyte is made under dry conditions to achieve the noted characteristics.
CERN PhotoLab
1978-01-01
The picture shows a "Flat-Fish" vacuum chamber being prepared in the ISR workshop for testing prior to installation in the Split Field Magnet (SFM) at intersection I4. The two shells of each part were hydroformed from 0.15 mm thick inconel 718 sheet (with end parts in inconel 600 for easier manual welding to the arms) and welded toghether with two strips which were attached by means of thin stainless steel sheets to the Split Field Magnet poles in order to take the vertical component of the atmospheric pressure force. This was the thinnest vacuum chamber ever made for the ISR. Inconel material was chosen for its high elastic modulus and strenght at chamber bake-out temperature. In this picture the thin sheets transferring the vertical component of the atmosferic pressure force are attached to a support frame for testing. See also 7712182, 7712179.
Determining Commuting Behaviour from Monitoring Technologies
Directory of Open Access Journals (Sweden)
Yuting You
2015-01-01
Full Text Available The study of commuting behaviour has always been one significant focus of people to reach comprehensive knowledge of transport-related scenarios. Similarly, commuting behaviour, as one of the four major physical activities people engaged in during daily life, gained much attention in aspect of health fields. This paper, with the sample data collected by The Australian Diabetes, Obesity and Lifestyle (AusDiab study, discusses the process of how to utilize data obtained from GPS and inclinometer device, along with basic information about participants to conduct travel survey, and reconstructing participant's commuting behaviour. In the analyses of the sample, the procedure of datasets integration through DELPHI programming and protocols established to determine corresponding commuting behaviour are discussed. The details of commuting behaviour illustrated in this study included travel mode, travel duration, allocation of trip stages, and corresponding level of physical activities. This paper discusses a promise for applying advanced technologies in travel survey instead of traditional ones in terms of accuracy and reliability; it discusses the feasibility to discover the coherent relationship between health outcome and commuting behaviour from travel-tracking technologies.
Young's modulus of multi-layer microcantilevers
Deng, Zhikang; Deng, Jinglan; He, Liang; Zhuo, Rongshu; Zhu, Ruiqi; Shi, Yang; Liu, Hui; Yang, Wei; Yuan, Hui; Chen, Yiming; Huang, Yue; Zheng, Yi
2017-12-01
A theoretical model for calculating the Young's modulus of multi-layer microcantilevers with a coating is proposed, and validated by a three-dimensional (3D) finite element (FE) model using ANSYS parametric design language (APDL) and atomic force microscopy (AFM) characterization. Compared with typical theoretical models (Rayleigh-Ritz model, Euler-Bernoulli (E-B) beam model and spring mass model), the proposed theoretical model can obtain Young's modulus of multi-layer microcantilevers more precisely. Also, the influences of coating's geometric dimensions on Young's modulus and resonant frequency of microcantilevers are discussed. The thickness of coating has a great influence on Young's modulus and resonant frequency of multi-layer microcantilevers, and the coating should be considered to calculate Young's modulus more precisely, especially when fairly thicker coating is employed.
Survey of how staff commute to work
2014-01-01
A survey was initiated by the Canton of Geneva (Direction Générale des Transports) and the Swiss Permanent Mission to the United Nations, and is aimed at better understanding how staff in International Organisations commute to/from work so as to better plan future works (road access, public transport, etc.). The ILO, WHO, UNAIDs, Global Fund, IFRC, CERN and UNOG are taking part in this important survey. People living in Switzerland or France are invited to respond to this survey. The purpose of this survey is to better understand: - your commuting habits, - your willingness to explore alternative commuting options, - your expectations and needs. All data provided to this external company (www.mobilidee.ch) will be kept confidential and will only be used for this particular study. CERN has received all guarantees of confidentiality from this company. Many thanks for your collaboration! GS Department
Non-Hamiltonian commutators in quantum mechanics.
Sergi, Alessandro
2005-12-01
The symplectic structure of quantum commutators is first unveiled and then exploited to describe generalized non-Hamiltonian brackets in quantum mechanics. It is easily recognized that quantum-classical systems are described by a particular realization of such a bracket. In light of previous work, this paper explains a unified approach to classical and quantum-classical non-Hamiltonian dynamics. In order to illustrate the use of non-Hamiltonian commutators, it is shown how to define thermodynamic constraints in quantum-classical systems. In particular, quantum-classical Nosé-Hoover equations of motion and the associated stationary density matrix are derived. The non-Hamiltonian commutators for both Nosé-Hoover chains and Nosé-Andersen (constant-pressure, constant-temperature) dynamics are also given. Perspectives of the formalism are discussed.
Commutative algebra constructive methods finite projective modules
Lombardi, Henri
2015-01-01
Translated from the popular French edition, this book offers a detailed introduction to various basic concepts, methods, principles, and results of commutative algebra. It takes a constructive viewpoint in commutative algebra and studies algorithmic approaches alongside several abstract classical theories. Indeed, it revisits these traditional topics with a new and simplifying manner, making the subject both accessible and innovative. The algorithmic aspects of such naturally abstract topics as Galois theory, Dedekind rings, Prüfer rings, finitely generated projective modules, dimension theory of commutative rings, and others in the current treatise, are all analysed in the spirit of the great developers of constructive algebra in the nineteenth century. This updated and revised edition contains over 350 well-arranged exercises, together with their helpful hints for solution. A basic knowledge of linear algebra, group theory, elementary number theory as well as the fundamentals of ring and module theory is r...
Commutability of food microbiology proficiency testing samples.
Abdelmassih, M; Polet, M; Goffaux, M-J; Planchon, V; Dierick, K; Mahillon, J
2014-03-01
Food microbiology proficiency testing (PT) is a useful tool to assess the analytical performances among laboratories. PT items should be close to routine samples to accurately evaluate the acceptability of the methods. However, most PT providers distribute exclusively artificial samples such as reference materials or irradiated foods. This raises the issue of the suitability of these samples because the equivalence-or 'commutability'-between results obtained on artificial vs. authentic food samples has not been demonstrated. In the clinical field, the use of noncommutable PT samples has led to erroneous evaluation of the performances when different analytical methods were used. This study aimed to provide a first assessment of the commutability of samples distributed in food microbiology PT. REQUASUD and IPH organized 13 food microbiology PTs including 10-28 participants. Three types of PT items were used: genuine food samples, sterile food samples and reference materials. The commutability of the artificial samples (reference material or sterile samples) was assessed by plotting the distribution of the results on natural and artificial PT samples. This comparison highlighted matrix-correlated issues when nonfood matrices, such as reference materials, were used. Artificially inoculated food samples, on the other hand, raised only isolated commutability issues. In the organization of a PT-scheme, authentic or artificially inoculated food samples are necessary to accurately evaluate the analytical performances. Reference materials, used as PT items because of their convenience, may present commutability issues leading to inaccurate penalizing conclusions for methods that would have provided accurate results on food samples. For the first time, the commutability of food microbiology PT samples was investigated. The nature of the samples provided by the organizer turned out to be an important factor because matrix effects can impact on the analytical results. © 2013
The Urbanik generalized convolutions in the non-commutative ...
Indian Academy of Sciences (India)
commutative probability; q-deformed convolution; weakly stable measure. 1. Introduction. In classical probability the convolution is an associative and commutative operation which preserves probability measures on the real line R. An alternative ...
Soft-commutated direct current motor
Energy Technology Data Exchange (ETDEWEB)
Hsu, J.S.
1999-07-27
A method and circuit is disclosed for soft-commutation of a direct current (DC) motor. An attenuation circuit is connected through auxiliary brushes A, A[prime], B and B[prime] to the commutator (16) to drain circuit from successive armature coils (15) before the main brushes (27, 28) disconnects from each of the coils (15). This prevents the spark generation that normally occurs in conventional DC motors. The attenuation circuit may also be connected before energization of the coil (15) for a soft turning on operation. 13 figs.
Soft-commutated direct current motor
Energy Technology Data Exchange (ETDEWEB)
Hsu, John S. (Oak Ridge, TN)
1999-01-01
A method and circuit is disclosed for soft-commutation of a direct current (DC) motor. An attenuation circuit is connected through auxiliary brushes A, A', B and B' to the commutator (16) to drain circuit from successive armature coils (15) before the main brushes (27, 28) disconnects from each of the coils (15). This prevents the spark generation that normally occurs in conventional DC motors. The attenuation circuit may also be connected before energization of the coil (15) for a soft turning on operation.
Coping with employment issues through commuting: Evidence from Central Russia
Directory of Open Access Journals (Sweden)
Gunko Maria
2017-06-01
Full Text Available Commuting to work has become a widespread practice over the last several decades. Some relatively strong employment issues in rural Russian municipalities, as well as a significant wage gap between them and the major cities, fosters daily commuting as well as commuting with long periods of time spent at employment locations, known in Russia as otkhodnichestvo. Based on official statistical data and our own surveys conducted in Tula and Kostroma regions, we analysed the spatial differentiations between the share of commuters in the employed population of rural municipalities, as well as the variations in individual socio-economic characteristics between rural commuters and non-commuters, in general, and between the commuters themselves. Our analysis of the latter characteristics suggests that there is in fact more difference between the rural commuters and non-commuters in Russia than between daily commuters and those engaged in otkhodnichestvo, indicating similar motives and, perhaps, even personalities of commuters. Giving the identified differences, commuting on a larger scale does not seem to be a universal tool to cope with employment issues, as some population groups are more likely to engage in it than others.
Commutating Permanent-Magnet Motors At Low Speed
Dolland, C.
1985-01-01
Circuit provides forced commutation during starting. Forced commutation circuit diverts current from inverter SCR's and turns SCR's off during commutation intervals. Silicon controlled rectifier in circuit unnecessary when switch S10 replaced by high-current, high-voltage transistor. At present, high-current, low-voltage device must suffice.
Modulus-Pressure Equation for Confined Fluids
Gor, Gennady Y; Shen, Vincent K; Bernstein, Noam
2016-01-01
Ultrasonic experiments allow one to measure the elastic modulus of bulk solid or fluid samples. Recently such experiments have been carried out on fluid-saturated nanoporous glass to probe the modulus of a confined fluid. In our previous work [J. Chem. Phys., (2015) 143, 194506], using Monte Carlo simulations we showed that the elastic modulus $K$ of a fluid confined in a mesopore is a function of the pore size. Here we focus on modulus-pressure dependence $K(P)$, which is linear for bulk materials, a relation known as the Tait-Murnaghan equation. Using transition-matrix Monte Carlo simulations we calculated the elastic modulus of bulk argon as a function of pressure and argon confined in silica mesopores as a function of Laplace pressure. Our calculations show that while the elastic modulus is strongly affected by confinement and temperature, the slope of the modulus versus pressure is not. Moreover, the calculated slope is in a good agreement with the reference data for bulk argon and experimental data for ...
Yanagawa, Youichi; Ohsaka, Hiromichi; Jitsuiki, Kei; Yoshizawa, Toshihiko; Takeuchi, Ikuto; Omori, Kazuhiko; Oode, Yasumasa; Ishikawa, Kouhei
2016-08-01
This article describes the theory of the formation of the vacuum phenomenon (VP), the detection of the VP, the different medical causes, the different locations of the presentation of the VP, and the differential diagnoses. In the human body, the cavitation effect is recognized on radiological studies; it is called the VP. The mechanism responsible for the formation of the VP is as follows: if an enclosed tissue space is allowed to expand as a rebound phenomenon after an external impact, the volume within the enclosed space will increase. In the setting of expanding volume, the pressure within the space will decrease. The solubility of the gas in the enclosed space will decrease as the pressure of the space decreases. Decreased solubility allows a gas to leave a solution. Clinically, the pathologies associated with the VP have been reported to mainly include the normal joint motion, degeneration of the intervertebral discs or joints, and trauma. The frequent use of CT for trauma patients and the high spatial resolution of CT images might produce the greatest number of chances to detect the VP in trauma patients. The VP is observed at locations that experience a traumatic impact; thus, an analysis of the VP may be useful for elucidating the mechanism of an injury. When the VP is located in the abdomen, it is important to include perforation of the digestive tract in the differential diagnosis. The presence of the VP in trauma patients does not itself influence the final outcome.
Active commuting to school in Portuguese adolescents
DEFF Research Database (Denmark)
Pizarro, Andreia Nogueira; Schipperijn, Jasper; Andersen, Henriette Bondo
2016-01-01
Abstract The declining levels of physical activity (PA) have led to active commuting to school (ACS) being seen as a key strategy to increase PA levels in school-aged children. In Portugal, no data exists on the patterns of this behavior, an essential step for developing evidence-based and effect...
Strong commutativity preserving generalized derivations on ...
African Journals Online (AJOL)
... standard polynomial identity on 4 non-commuting variables, then there exist s; c ∈ U such that F(x) = xs, G(x) = cx, for all x ∈ R, and sc = 1C (the unit of C). We also study the semiprime case. Mathematics Subject Classification (2010): 16W25, 16N60. Key words: Prime rings, differential identities, generalized derivations.
Happiness and Satisfaction with Work Commute
Olsson, L.E.; Gärling, T.; Ettema, D.F.; Friman, M.; Fujii, S.
2012-01-01
Research suggests that for many people happiness is being able to make the routines of everyday life work, such that positive feelings dominate over negative feelings resulting from daily hassles. In line with this, a survey of work commuters in the three largest urban areas of Sweden show that
Examining individuals' desire for shorter commute: the case of proximate commuting
Daniel A Rodríguez
2002-01-01
Much of the theoretical and empirical debate about transport and land-use planning has focused upon the strength and vitality of the connection between the two. Studies increasingly find that this connection is weakening and thus attempts to address urban transport problems with land-use policies are ineffective. The author introduces proximate commuting, a novel employer-based program that decreases urban commuting by providing marginal accessibility improvements to its participants. With th...
Solving the {eta}-Problem in hybrid inflation with Heisenberg symmetry and stabilized modulus
Energy Technology Data Exchange (ETDEWEB)
Antusch, Stefan; Dutta, Koushik; Kostka, Philipp [Max-Planck-Institut fuer Physik, Werner-Heisenberg-Institut, Muenchen (Germany); Bastero-Gil, Mar [Departamento de Fisica Teorica y del Cosmos and Centro Andaluz de Fisica de Particulas Elementales, Universidad de Granada (Spain); King, Steve [School of Physics and Astronomy, University of Southampton (United Kingdom)
2009-07-01
We present a new class of models in which the {eta}-problem of supersymmetric hybrid inflation is resolved using a Heisenberg symmetry, where the associated modulus field is stabilized and made heavy with the help of the large vacuum energy during inflation without any fine-tuning. A natural candidate for the inflaton in this class of models is the right-handed sneutrino which is massless during the inflationary epoch, and subsequently acquires a large mass at the end of inflation.
Non-commutative covering spaces and their symmetries
DEFF Research Database (Denmark)
Canlubo, Clarisson
-commutative covering space using Galois theory of Hopfalgebroids. We will look at basic properties of classical covering spaces that generalize to thenon-commutative framework. Afterwards, we will explore a series of examples. We will startwith coverings of a point and central coverings of commutative spaces and see...... how these areclosely tied up. Coupled Hopf algebras will be presented to give a general description of coveringsof a point. We will give a complete description of the geometry of the central coverings ofcommutative spaces using the coverings of a point. A topologized version of Hopf categories willbe...... the non-commutative analogue of the hyperelliptic involution, we will showthat unlike the classical case, the non-commutative sphere is a covering of the non-commutativetorus. There is a purely non-commutative phenomenon happening to non-commutative coverings,namely, their symmetry is two-sided. We...
Determination of Modulus of Elasticity and Shear Modulus by the Measurement of Relative Strains
Labašová, Eva
2016-12-01
This contribution is focused on determining the material properties (Young modulus and shear modulus) of the testing samples. The theoretical basis for determining material properties are the knowledge of linear elasticity and strength. The starting points are dependencies among the modulus of elasticity, shear modulus, normal stress and relative strain. The relative strains of the testing samples were obtained by measuring predefined load conditions using a strain-gauge bridge and the universal measurement system Quantum X MX 840. The integration of these tasks into the teaching process enhances practical and intellectual skills of students at secondary level technical universities.
Determination of Modulus of Elasticity and Shear Modulus by the Measurement of Relative Strains
Directory of Open Access Journals (Sweden)
Labašová Eva
2016-12-01
Full Text Available This contribution is focused on determining the material properties (Young modulus and shear modulus of the testing samples. The theoretical basis for determining material properties are the knowledge of linear elasticity and strength. The starting points are dependencies among the modulus of elasticity, shear modulus, normal stress and relative strain. The relative strains of the testing samples were obtained by measuring predefined load conditions using a strain-gauge bridge and the universal measurement system Quantum X MX 840. The integration of these tasks into the teaching process enhances practical and intellectual skills of students at secondary level technical universities.
Quantifying commuter exposures to volatile organic compounds
Kayne, Ashleigh
Motor-vehicles can be a predominant source of air pollution in cities. Traffic-related air pollution is often unavoidable for people who live in populous areas. Commuters may have high exposures to traffic-related air pollution as they are close to vehicle tailpipes. Volatile organic compounds (VOCs) are one class of air pollutants of concern because exposure to VOCs carries risk for adverse health effects. Specific VOCs of interest for this work include benzene, toluene, ethylbenzene, and xylenes (BTEX), which are often found in gasoline and combustion products. Although methods exist to measure time-integrated personal exposures to BTEX, there are few practical methods to measure a commuter's time-resolved BTEX exposure which could identify peak exposures that could be concealed with a time-integrated measurement. This study evaluated the ability of a photoionization detector (PID) to measure commuters' exposure to BTEX using Tenax TA samples as a reference and quantified the difference in BTEX exposure between cyclists and drivers with windows open and closed. To determine the suitability of two measurement methods (PID and Tenax TA) for use in this study, the precision, linearity, and limits of detection (LODs) for both the PID and Tenax TA measurement methods were determined in the laboratory with standard BTEX calibration gases. Volunteers commuted from their homes to their work places by cycling or driving while wearing a personal exposure backpack containing a collocated PID and Tenax TA sampler. Volunteers completed a survey and indicated if the windows in their vehicle were open or closed. Comparing pairs of exposure data from the Tenax TA and PID sampling methods determined the suitability of the PID to measure the BTEX exposures of commuters. The difference between BTEX exposures of cyclists and drivers with windows open and closed in Fort Collins was determined. Both the PID and Tenax TA measurement methods were precise and linear when evaluated in the
Dynamics in Braess Paradox with Nonimpulsive Commuters
Directory of Open Access Journals (Sweden)
Arianna Dal Forno
2015-01-01
the individual rationality leads to collective irrationality. In the literature, the dynamics has been analyzed when considering impulsive commuters, i.e., those who switch choice regardless of the actual difference between costs. We analyze a dynamical version of the paradox with nonimpulsive commuters, who change road proportionally to the cost difference. When only two roads are available, we provide a rigorous proof of the existence of a unique fixed point showing that it is globally attracting even if locally unstable. When a new road is added the system becomes discontinuous and two-dimensional. We prove that still a unique fixed point exists, and its global attractivity is numerically evidenced, also when the fixed point is locally unstable. Our analysis adds a new insight in the understanding of dynamics in social dilemma.
Discrete choice models for commuting interactions
DEFF Research Database (Denmark)
Rouwendal, Jan; Mulalic, Ismir; Levkovich, Or
An emerging quantitative spatial economics literature models commuting interactions by a gravity equation that is mathematically equivalent to a multinomial logit model. This model is widely viewed as restrictive because of the independence of irrelevant alternatives (IIA) property that links...... substitution behavior in response to changes in the attractiveness of choice alternatives to choice probabilities in a mechanistic way. This is relevant for counterfactual analysis. In this paper we examine the appropriateness of the commuting model from a theoretical as well as an empirical point of view. We...... show that conventional specification tests of the multinomial logit model are of limited use when alternative specific constants are used, as is common in the recent literature, and offer no information with respect to the validity of IIA. In articular, we show that maximum likelihood estimation...
Influence of substrate modulus on gecko adhesion
Klittich, Mena R.; Wilson, Michael C.; Bernard, Craig; Rodrigo, Rochelle M.; Keith, Austin J.; Niewiarowski, Peter H.; Dhinojwala, Ali
2017-01-01
The gecko adhesion system fascinates biologists and materials scientists alike for its strong, reversible, glue-free, dry adhesion. Understanding the adhesion system’s performance on various surfaces can give clues as to gecko behaviour, as well as towards designing synthetic adhesive mimics. Geckos encounter a variety of surfaces in their natural habitats; tropical geckos, such as Gekko gecko, encounter hard, rough tree trunks as well as soft, flexible leaves. While gecko adhesion on hard surfaces has been extensively studied, little work has been done on soft surfaces. Here, we investigate for the first time the influence of macroscale and nanoscale substrate modulus on whole animal adhesion on two different substrates (cellulose acetate and polydimethylsiloxane) in air and find that across 5 orders of magnitude in macroscale modulus, there is no change in adhesion. On the nanoscale, however, gecko adhesion is shown to depend on substrate modulus. This suggests that low surface-layer modulus may inhibit the gecko adhesion system, independent of other influencing factors such as macroscale composite modulus and surface energy. Understanding the limits of gecko adhesion is vital for clarifying adhesive mechanisms and in the design of synthetic adhesives for soft substrates (including for biomedical applications and wearable electronics). PMID:28287647
Influence of substrate modulus on gecko adhesion
Klittich, Mena R.; Wilson, Michael C.; Bernard, Craig; Rodrigo, Rochelle M.; Keith, Austin J.; Niewiarowski, Peter H.; Dhinojwala, Ali
2017-03-01
The gecko adhesion system fascinates biologists and materials scientists alike for its strong, reversible, glue-free, dry adhesion. Understanding the adhesion system’s performance on various surfaces can give clues as to gecko behaviour, as well as towards designing synthetic adhesive mimics. Geckos encounter a variety of surfaces in their natural habitats; tropical geckos, such as Gekko gecko, encounter hard, rough tree trunks as well as soft, flexible leaves. While gecko adhesion on hard surfaces has been extensively studied, little work has been done on soft surfaces. Here, we investigate for the first time the influence of macroscale and nanoscale substrate modulus on whole animal adhesion on two different substrates (cellulose acetate and polydimethylsiloxane) in air and find that across 5 orders of magnitude in macroscale modulus, there is no change in adhesion. On the nanoscale, however, gecko adhesion is shown to depend on substrate modulus. This suggests that low surface-layer modulus may inhibit the gecko adhesion system, independent of other influencing factors such as macroscale composite modulus and surface energy. Understanding the limits of gecko adhesion is vital for clarifying adhesive mechanisms and in the design of synthetic adhesives for soft substrates (including for biomedical applications and wearable electronics).
Expanded commuting in the metropolitan region of Belo Horizonte: evidence for reverse commuting
Directory of Open Access Journals (Sweden)
Carlos Lobo
2015-08-01
Full Text Available AbstractLarge Brazilian cities, particularly those that have experienced rapid population growth since the middle of the last century, have exhibited significant signs of population dispersion in their peripheries in recent decades. A study of the population’s spatial redistribution in the Metropolitan Region of Belo Horizonte (MRBH confirms this finding. In the process of dispersion, the levels of urban commuting increase, and commuting becomes a relevant indicator of the degree of integration within the metropolis. This paper evaluates the current magnitude and main features of reverse commuting, as characterized by the daily displacements of the population that resides not in the periphery but rather in the core. Flows from the metropolitan core towards the peripheral municipalities are examined using sample microdata on the MRBH municipalities from the 2000 and 2010 demographic censuses by combining the variables of "municipality of residence" and "municipality of work/study." The results indicate an increase in reverse commuting in both absolute and relative terms. When this flow is compared totraditional commuting (periphery/center, the relative values are considerable. In some cases, this relationship reaches notably high values, as the case of Confins (the municipality where the international airport is located, and also municipalities that are part of a relatively old conurbation, such as Nova Lima and Betim.
Eulerian Dynamics with a Commutator Forcing
2017-01-09
EULERIAN DYNAMICS WITH A COMMUTATOR FORCING ROMAN SHVYDKOY AND EITAN TADMOR Abstract. We study a general class of Euler equations driven by a forcing...visit which initiated this work. Finally we thank the Institute for Theoretical Studies (ITS) at ETH-Zurich for the hospitality. 1 2 ROMAN SHVYDKOY AND...well. 4 ROMAN SHVYDKOY AND EITAN TADMOR Theorem 1.1. Consider the hydrodynamics flocking model (1.10) with a bounded mollifier, φ ∈ L∞# having a
Sensorless Commutation Control of Switched Reluctance Motor
N.H. Mvungi
2007-01-01
This paper addresses control of commutation of switched reluctance (SR) motor without the use of a physical position detector. Rotor position detection schemes for SR motor based on magnetisation characteristics of the motor use normal excitation or applied current /voltage pulses. The resulting schemes are referred to as passive or active methods respectively. The research effort is in realizing an economical sensorless SR rotor position detector that is accurate, reliable and robust to suit...
FET commutated current-FED inverter
Rippel, Wally E. (Inventor); Edwards, Dean B. (Inventor)
1983-01-01
A shunt switch comprised of a field-effect transistor (Q.sub.1) is employed to commutate a current-fed inverter (10) using thyristors (SCR1, SCR2) or bijunction transistors (Q.sub.2, Q.sub.3) in a full bridge (1, 2, 3, 4) or half bridge (5, 6) and transformer (T.sub.1) configuration. In the case of thyristors, a tapped inverter (12) is employed to couple the inverter to a dc source to back bias the thyristors during commutation. Alternatively, a commutation power supply (20) may be employed for that purpse. Diodes (D.sub.1, D.sub.2) in series with some voltage dropping element (resistor R.sub.12 or resistors R.sub.1, R.sub.2 or Zener diodes D.sub.4, D.sub.5) are connected in parallel with the thyristors in the half bridge and transformer configuration to assure sharing the back bias voltage. A clamp circuit comprised of a winding (18) negatively coupled to the inductor and a diode (D.sub.3) return stored energy from the inductor to the power supply for efficient operation with buck or boost mode.
Measuring shear modulus of individual fibers
Behlow, Herbert; Saini, Deepika; Oliviera, Luciana; Skove, Malcolm; Rao, Apparao
2014-03-01
Fiber technology has advanced to new heights enabling tailored mechanical properties. For reliable fiber applications their mechanical properties must be well characterized at the individual fiber level. Unlike the tensile modulus, which can be well studied in a single fiber, the present indirect and dynamic methods of measuring the shear properties of fibers suffer from various disadvantages such as the interaction between fibers and the influence of damping. In this talk, we introduce a quasi-static method to directly measure the shear modulus of a single micron-sized fiber. Our simple and inexpensive setup yields a shear modulus of 16 and 2 GPa for a single IM7 carbon fiber and a Kevlar fiber, respectively. Furthermore, our setup is also capable of measuring the creep, hysteresis and the torsion coefficient, and examples of these will be presented.
Commuting Pattern with Park-and-Ride Option for Heterogeneous Commuters
Directory of Open Access Journals (Sweden)
Chengjuan Zhu
2013-01-01
Full Text Available We study the effect of the parking on heterogeneous commuters' travel choice in a competitive transportation system which consists of a subway and a parallel road with a bottleneck of limited service capacity. Every morning, commuters either use their private cars only or drive their cars to the bottleneck, park there, and then take the subway to the destination. Considering the effects caused by body congestion in carriage and the parking fees, we developed a bottleneck model to describe the commuters' travel choice. There exist several types of equilibrium that corresponds to user equilibrium. We investigated the influence of the capacity of the bottleneck and the total travel demand on the travel behaviors and on the total social cost. It is shown that there exists a scheme with suitable subway fare and parking fees to implement the minimum total social cost.
The effect of sprawl on private-vehicle commuting outcomes
Edmund J Zolnik
2011-01-01
Amongst the hypothesized beneficial impacts of sprawl on urban quality of life is a decrease in commuting times. Unfortunately, empirical evidence to substantiate the commuting time benefits of sprawl is scant. To address this void in the urban planning literature, a multilevel approach is adopted to study how sprawl affects the duration and length of private-vehicle commutes. Using microdata from the 2001 National Household Transportation Survey for individuals and microdata on various measu...
On the Commutativity of a Certain Class of Toeplitz Operators
Directory of Open Access Journals (Sweden)
Louhichi Issam
2014-01-01
Full Text Available One of the major goals in the theory of Toeplitz operators on the Bergman space over the unit disk D in the complex place C is to completely describe the commutant of a given Toeplitz operator, that is, the set of all Toeplitz operators that commute with it. Here we shall study the commutants of a certain class of quasihomogeneous Toeplitz operators defined on the harmonic Bergman space.
On a weighted Toeplitz operator and its commutant
Directory of Open Access Journals (Sweden)
Vasile Lauric
2005-05-01
Full Text Available We study the structure of a class of weighted Toeplitz operators and obtain a description of the commutant of each operator in this class. We make some progress towards proving that the only operator in the commutant which is not a scalar multiple of the identity operator and which commutes with a nonzero compact operator is zero. The proof of the main statement relies on a conjecture which is left as an open problem.
Self-commutating converters for high power applications
Arrillaga, Jos; Watson, Neville R; Murray, Nicholas J
2010-01-01
For very high voltage or very high current applications, the power industry still relies on thyristor-based Line Commutated Conversion (LCC), which limits the power controllability to two quadrant operation. However, the ratings of self-commutating switches such as the Insulated-Gate Bipolar Transistor (IGBT) and Integrated Gate-Commutated Thyristor (IGCT), are reaching levels that make the technology possible for very high power applications. This unique book reviews the present state and future prospects of self-commutating static power converters for applications requiring either ultr
Exploring characteristics and motives of long distance commuter cyclists
DEFF Research Database (Denmark)
Hansen, Karsten Bruun; Nielsen, Thomas Alexander Sick
2014-01-01
, commuter cyclists (>5 km from home to work) have more mobility options, higher incomes, and a longer education than other commuter cyclists. The main motive for longer distance cycling is physical exercise, followed by reduced costs and time used for traveling. The long distance commuter cyclists surveyed...... are very positive about their commute - pointing to positive experiences, better mood, and stress relief as experiences related to their cycle trip to work. Policy support should devote attention to unlocking the potential that may be embedded in individuals combining their exercise and travel time...
Expanding space-time and variable vacuum energy
Parmeggiani, Claudio
2017-08-01
The paper describes a cosmological model which contemplates the presence of a vacuum energy varying, very slightly (now), with time. The constant part of the vacuum energy generated, some 6 Gyr ago, a deceleration/acceleration transition of the metric expansion; so now, in an aged Universe, the expansion is inexorably accelerating. The vacuum energy varying part is instead assumed to be eventually responsible of an acceleration/deceleration transition, which occurred about 14 Gyr ago; this transition has a dynamic origin: it is a consequence of the general relativistic Einstein-Friedmann equations. Moreover, the vacuum energy (constant and variable) is here related to the zero-point energy of some quantum fields (scalar, vector, or spinor); these fields are necessarily described in a general relativistic way: their structure depends on the space-time metric, typically non-flat. More precisely, the commutators of the (quantum field) creation/annihilation operators are here assumed to depend on the local value of the space-time metric tensor (and eventually of its curvature); furthermore, these commutators rapidly decrease for high momentum values and they reduce to the standard ones for a flat metric. In this way, the theory is ”gravitationally” regularized; in particular, the zero-point (vacuum) energy density has a well defined value and, for a non static metric, depends on the (cosmic) time. Note that this varying vacuum energy can be negative (Fermi fields) and that a change of its sign typically leads to a minimum for the metric expansion factor (a ”bounce”).
Evaluation of Antenna Foundation Elastic Modulus
Mcginness, H.; Anderson, G.
1983-01-01
An experiment to measure the elastic deflection of the DSS 14 concrete pedestal under the weight of the antenna was conducted in February 1983 and is compared to a similiar experiment made in 1968. Comparison of the results confirms the decrease in elastic modulus measured on core samples recently taken from the pedestal.
Measuring Elastic Modulus of Sintered Metal
Fedors, R. F.; Eastman, A. F.
1983-01-01
Technique minimizes effect of substrate on thin sintered coating. Uniaxial tension test yields approximate value for elastic modulus of sintered material on thin substrate. Electrode composed of central perforated nickel plated steel sheet about 4 mils (0.1mm) thick, coated on each face by porous sintered nickel about 8 mils (0.2mm) thick.
Structural relaxation monitored by instantaneous shear modulus
DEFF Research Database (Denmark)
Olsen, Niels Boye; Dyre, Jeppe; Christensen, Tage Emil
1998-01-01
This paper reports on aging of the silicone oil MS704 for sudden changes of temperature from 210.5 to 209.0 K and from 207.5 to 209.0 K studied by continuously monitoring the instantaneous shear modulus G [infinity]. The results are interpreted within the Tool-Narayanaswamy formalism with a reduced...
Analysis of bed joint influence on masonry modulus of elasticity
Zavalis, R.; Jonaitis, B.; Paulo B. Lourenço
2014-01-01
The means of determining the modulus of elasticity presented in technical literature often underestimate factors such as the influence of mechanical properties of the bed joint mortar and the influence of contact zone of the masonry unit and mortar on the elasticity modulus. Research carried out by the authors show that the modulus of elasticity of the bed joint considering influence of the contact zone (effective modulus of elasticity) is 3 to 25 times less than mortar modulus of...
Measuring Propellant Stress Relaxation Modulus Using Dynamic Mechanical Analyzer
2017-03-29
Article 3. DATES COVERED (From - To) 04 August 2016 – 29 March 2017 4. TITLE AND SUBTITLE Measuring Propellant Stress Relaxation Modulus Using Dynamic...ERC 14. ABSTRACT A method for determining the stress relaxation master curve of solid rocket propellants was developed. The propellant was tested in... stress relaxation modulus, Mpa; E∞ = long-term equilibrium modulus, Mpa; E0 = storage modulus, Mpa; E0 0 = loss modulus, Mpa; F = Fisher test
The effect of commuting microenvironment on commuter exposures to vehicular emission in Hong Kong
Chan, L. Y.; Chan, C. Y.; Qin, Y.
Vehicular exhaust emission has gradually become the major air pollution source in modern cities and traffic related exposure is found to contribute significantly to total human exposure level. A comprehensive survey was conducted from November 1995 to July 1996 in Hong Kong to assess the effect of traffic-induced air pollution inside different commuting microenvironments on commuter exposure. Microenvironmental monitoring is performed for six major public commuting modes (bus, light bus, MTR, railway, tram, ferry), plus private car and roadside pavement. Traffic-related pollutants, CO, NO x, THC and O 3 were selected as the target pollutants. The results indicate that commuter exposure is highly influenced by the choice of commuting microenvironment. In general, the exposure level in decreasing order of measured pollutant level for respective commuting microenvironments are: private car, the group consisting light bus, bus, tram and pavement, MTR and train, and finally ferry. In private car, the CO level is several times higher than that in the other microenvironments with a trip averaged of 10.1 ppm and a maximum of 24.9 ppm. Factors such as the body position of the vehicle, intake point of the ventilation system, fuel used, ventilation, transport mode, road and driving conditions were used in the analysis. Inter-microenvironment, intra-microenvironment and temporal variation of CO concentrations were used as the major indicator. The low body position and low intake point of the ventilation system of the private car are believed to be the cause of higher intake of exhaust of other vehicles and thus result in high pollution level in this microenvironment. Compared with other metropolis around the world and the Hong Kong Air Quality Objectives (HKAQO), exposure levels of commuter to traffic-related air pollution in Hong Kong are relatively low for most pollutants measured. Only several cases of exceedence of HKAQO by NO 2 were recorded. The strong prevailing wind
Theory of generalized inverses over commutative rings
Bhaskara Rao, KPS
2003-01-01
The theory of generalized inverses of real or complex matrices has been expertly developed and documented. But the generalized inverses of matrices over rings have received comprehensive treatment only recently. In this book, the author, who contributed to the research and development of the theory, explains his results. He explores regular elements in a ring, regular matrices over principal ideal rings, and regular matrices over commutative rings. Students, mathematicians working in g-inverses of matrices, along with algebraists, and control theorists will find new and indispensable data, presented with clarity and insight. This book is also well suited to graduate courses on g-inverses in algebra.
Nanoscale Vacuum Channel Transistor.
Han, Jin-Woo; Moon, Dong-Il; Meyyappan, M
2017-04-12
Vacuum tubes that sparked the electronics era had given way to semiconductor transistors. Despite their faster operation and better immunity to noise and radiation compared to the transistors, the vacuum device technology became extinct due to the high power consumption, integration difficulties, and short lifetime of the vacuum tubes. We combine the best of vacuum tubes and modern silicon nanofabrication technology here. The surround gate nanoscale vacuum channel transistor consists of sharp source and drain electrodes separated by sub-50 nm vacuum channel with a source to gate distance of 10 nm. This transistor performs at a low voltage (3 microamperes). The nanoscale vacuum channel transistor can be a possible alternative to semiconductor transistors beyond Moore's law.
Noise exposure during commuting in three European cities
Taimisto, P.; Yli-Tuomi, T.; Pennanen, A.; Vouitsis, I.; Samaras, Z.; Keuken, M.P.; Lanki, T.
2013-01-01
In the TRANSPHORM study, noise exposures during commuting were measured. Measurements were performed with noise dosimeters in three European cities, Helsinki, Thessaloniki and Rotterdam, during spring 2011. ln each city, two to five approximately 8 km commuting routes were selected to represent
Soft commutated direct current motor [summary of proposed paper
Energy Technology Data Exchange (ETDEWEB)
Hsu, John S.
1998-10-22
A novel soft commutated direct current (DC) motor is introduced. The current of the commutated coil is intentionally drained before the brush disconnects the coil. This prevents the spark generation that normally occurs in conventional DC motors. A similar principle can be applied for DC generators.
An improved 4-step commutation method application for matrix converter
DEFF Research Database (Denmark)
Guo, Yu; Guo, Yougui; Deng, Wenlang
2014-01-01
A novel four-step commutation method is proposed for matrix converter cell, 3 phase inputs to 1 phase output in this paper, which is obtained on the analysis of published commutation methods for matrix converter. The first and fourth step can be shorter than the second or third one. The discussed...
a generalization of zero divisor graphs associated to commutative ...
Indian Academy of Sciences (India)
8
zero divisor graph of R. In this paper, we study some basic properties of Γn. R. We also determine all isomorphic classes of finite commutative rings whose generalized zero divisor graphs have genus at most three. 1. Introduction. Let R be a commutative ring with a nonzero identity element, and let Z(R) be the set of all zero ...
26 CFR 1.46-11 - Commuter highway vehicles.
2010-04-01
... Rules for Computing Credit for Investment in Certain Depreciable Property § 1.46-11 Commuter highway... investment under section 46(c)(1) for a qualifying commuter highway vehicle is 100 percent. A qualifying... meets the following requirements: (1) The vehicle is section 38 property in the hands of the taxpayer...
Commutators with idempotent values on multilinear polynomials in ...
Indian Academy of Sciences (India)
Introduction and statements of the result. In mid-forties, after the development of the general structure theory for rings, a great deal of work was done that showed that under certain types of hypothesis, rings had to be commutative or almost commutative. A classical result of ring theory established by Jacobson generalizes at ...
Geometry, commutation relations and the quantum fictitious force
DEFF Research Database (Denmark)
Botero, J.; Cirone, M.A.; Dahl, Jens Peder
2003-01-01
We express the commutation relation between the operators of the momentum and the radial unit vectors in D dimensions in differential and integral form. We connect this commutator with the quantum fictitious potential emerging in the radial Schrodinger equation of an s-wave....
Non-commutative relativistic equation with a Coulomb potential
Energy Technology Data Exchange (ETDEWEB)
Zaim, Slimane; Khodja, Lamine; Delenda, Yazid [Departement de Physique, Faculte des Sciences, Universite Hadj Lakhdar - Batna (Algeria); Departement de Physique, Faculte des Sciences Exactes, Universite de Bejaia (Algeria); Departement de Physique, Faculte des Sciences, Universite Hadj Lakhdar - Batna (Algeria)
2012-06-27
We improve the previous study of the Klein-Gordon equation in a non-commutative space-time as applied to the Hydrogen atom to extract the energy levels, by considering the secondorder corrections in the non-commutativity parameter. Phenomenologically we show that noncommutativity plays the role of spin.
Homogeneous Buchberger algorithms and Sullivant's computational commutative algebra challenge
DEFF Research Database (Denmark)
Lauritzen, Niels
2005-01-01
We give a variant of the homogeneous Buchberger algorithm for positively graded lattice ideals. Using this algorithm we solve the Sullivant computational commutative algebra challenge.......We give a variant of the homogeneous Buchberger algorithm for positively graded lattice ideals. Using this algorithm we solve the Sullivant computational commutative algebra challenge....
Indian Vacuum Society: The Indian Vacuum Society
Saha, T. K.
2008-03-01
The Indian Vacuum Society (IVS) was established in 1970. It has over 800 members including many from Industry and R & D Institutions spread throughout India. The society has an active chapter at Kolkata. The society was formed with the main aim to promote, encourage and develop the growth of Vacuum Science, Techniques and Applications in India. In order to achieve this aim it has conducted a number of short term courses at graduate and technician levels on vacuum science and technology on topics ranging from low vacuum to ultrahigh vacuum So far it has conducted 39 such courses at different parts of the country and imparted training to more than 1200 persons in the field. Some of these courses were in-plant training courses conducted on the premises of the establishment and designed to take care of the special needs of the establishment. IVS also regularly conducts national and international seminars and symposia on vacuum science and technology with special emphasis on some theme related to applications of vacuum. A large number of delegates from all over India take part in the deliberations of such seminars and symposia and present their work. IVS also arranges technical visits to different industries and research institutes. The society also helped in the UNESCO sponsored post-graduate level courses in vacuum science, technology and applications conducted by Mumbai University. The society has also designed a certificate and diploma course for graduate level students studying vacuum science and technology and has submitted a syllabus to the academic council of the University of Mumbai for their approval, we hope that some colleges affiliated to the university will start this course from the coming academic year. IVS extended its support in standardizing many of the vacuum instruments and played a vital role in helping to set up a Regional Testing Centre along with BARC. As part of the development of vacuum education, the society arranges the participation of
Reducing employee travelling time through smart commuting
Rahman, A. N. N. A.; Yusoff, Z. M.; Aziz, I. S.; Omar, D.
2014-02-01
Extremely congested roads will definitely delay the arrival time of each trip.This certainly impacted the journey of employees. Tardiness at the workplace has become a perturbing issue for companies where traffic jams are the most common worker excuses. A depressing consequence on daily life and productivity of the employee occurs. The issues of commuting distance between workplace and resident area become the core point of this research. This research will emphasize the use of Geographical Information System (GIS) technique to explore the distance parameter to the employment area and will focus on the accessibility pattern of low-cost housing. The research methodology consists of interview sessions and a questionnaire to residents of low-cost housing areas in Melaka Tengah District in Malaysia. The combination of these processes will show the criteria from the selected parameter for each respondent from their resident area to the employment area. This will further help in the recommendation of several options for a better commute or improvement to the existing routes and public transportations system. Thus enhancing quality of life for employees and helping to reduce stress, decrease lateness, absenteeism and improving productivity in workplace.
Shock Waves and Commutation Speed of Memristors
Tang, Shao; Tesler, Federico; Marlasca, Fernando Gomez; Levy, Pablo; Dobrosavljević, V.; Rozenberg, Marcelo
2016-01-01
Progress of silicon-based technology is nearing its physical limit, as the minimum feature size of components is reaching a mere 10 nm. The resistive switching behavior of transition metal oxides and the associated memristor device is emerging as a competitive technology for next-generation electronics. Significant progress has already been made in the past decade, and devices are beginning to hit the market; however, this progress has mainly been the result of empirical trial and error. Hence, gaining theoretical insight is of the essence. In the present work, we report the striking result of a connection between the resistive switching and shock-wave formation, a classic topic of nonlinear dynamics. We argue that the profile of oxygen vacancies that migrate during the commutation forms a shock wave that propagates through a highly resistive region of the device. We validate the scenario by means of model simulations and experiments in a manganese-oxide-based memristor device, and we extend our theory to the case of binary oxides. The shock-wave scenario brings unprecedented physical insight and enables us to rationalize the process of oxygen-vacancy-driven resistive change with direct implications for a key technological aspect—the commutation speed.
High Strength and High Modulus Electrospun Nanofibers
Jian Yao; Cees W. M. Bastiaansen; Ton Peijs
2014-01-01
Electrospinning is a rapidly growing polymer processing technology as it provides a viable and simple method to create ultra-fine continuous fibers. This paper presents an in-depth review of the mechanical properties of electrospun fibers and particularly focuses on methodologies to generate high strength and high modulus nanofibers. As such, it aims to provide some guidance to future research activities in the area of high performance electrospun fibers.
Fibonacci difference sequence spaces for modulus functions
Directory of Open Access Journals (Sweden)
Kuldip Raj
2015-05-01
Full Text Available In the present paper we introduce Fibonacci difference sequence spaces l(F, Ƒ, p, u and l_∞(F, Ƒ, p, u by using a sequence of modulus functions and a new band matrix F. We also make an effort to study some inclusion relations, topological and geometric properties of these spaces. Furthermore, the alpha, beta, gamma duals and matrix transformation of the space l(F, Ƒ, p, u are determined.
Modulus for the coal ash. Summary
Energy Technology Data Exchange (ETDEWEB)
Rank, V.
1944-06-30
This summary outlined the procedure for obtaining a modulus to determine the effects of varying ash content. This modulus was to indicate the relative amounts of aluminum oxide and silicon dioxide after addition of alkalais or alkaline-earth constituents found in catalysts. The calculation of the modulus was based upon stoichiometric ratios of these oxides to other major components of ash as represented in the major minerals in the ash. The assumptions about the conditions in low- to intermediate-temperature coking included the following: (1) magnesium oxide was found only in biotite, which contained potassium oxide, magnesium oxide, aluminum oxide, silicon dioxide, and water in the respective mole ratios 1:4:2:6:1. (2) Potassium oxide outside of biotite was found only in muscovite, which contained potassium oxide, aluminum oxide, silicon dioxide, and water in the respective mole ratios 1:1:6:2. (3) Sodium oxide was combined only with aluminum oxide and silicon dioxide in the mole ratios 1:1:6. (4) Phosphoric acid was found as aluminum phosphate. (5) Lime was found in anortite, which contained calcium sulfate, calcium carbonate, or calcium oxide combined with aluminum oxide and silicon dioxide in the mole ratios 1:1:2. (6) Aluminum oxide and silicon dioxide existed mainly in the hydrated state with the two of them combined with water in the mole ratios 1:2:2. The completed formula for the modulus was given as M = (aluminum oxide) + (silicon dioxide) - 0.65(magnesium oxide) - 4.90(potassium oxide + sodium oxide) - 3.96(calcium oxide) - 0.72(phosphorous pentoxide), where the parentheses should be filled by numbers in weight units for the respective compounds.
Euler polynomials and identities for non-commutative operators
De Angelis, Valerio; Vignat, Christophe
2015-12-01
Three kinds of identities involving non-commutating operators and Euler and Bernoulli polynomials are studied. The first identity, as given by Bender and Bettencourt [Phys. Rev. D 54(12), 7710-7723 (1996)], expresses the nested commutator of the Hamiltonian and momentum operators as the commutator of the momentum and the shifted Euler polynomial of the Hamiltonian. The second one, by Pain [J. Phys. A: Math. Theor. 46, 035304 (2013)], links the commutators and anti-commutators of the monomials of the position and momentum operators. The third appears in a work by Figuieira de Morisson and Fring [J. Phys. A: Math. Gen. 39, 9269 (2006)] in the context of non-Hermitian Hamiltonian systems. In each case, we provide several proofs and extensions of these identities that highlight the role of Euler and Bernoulli polynomials.
Socioeconomic, Personal and Behavioral Correlates of Active Commuting among Adolescents
Directory of Open Access Journals (Sweden)
Adilson Marques
2016-03-01
Full Text Available The aims of this study were to assess the relationships between commuting to and from school (active vs. passive and their explanatory variables. A total of 2653 adolescents (1361 boys, 1292 girls; M age=13.4±2.6 participated in this study. The students were questioned about commuting to and from school, physical activity and school sports participation and perceptions of competence and health. Socioeconomic status and body mass index were calculated. Results show that a minority of the students use active transportation to and from school. Also, age increasing, participation in school sports and increasing duration were positively correlated with active commuting for both routes (to and from school. Given that active commuting may be a simple and effective way to increase physical activity level among youth populations, it is important to promote, improve conditions and create strategies in order to increase the number of students that actively commute to and from school.
Bulk Modulus Relaxation in Partially Molten Dunite?
Jackson, I.; Cline, C. J., II
2016-12-01
Synthetic solgel-derived Fo90 olivine was mixed with 3.5 wt % basaltic glass and hot-pressed within Ni/Fe foil to produce a dense aggregate expected to contain a small melt fraction at temperatures ≥ 1100°C. This specimen was precision ground and tested in both torsional and flexural forced oscillation to determine the relaxation behavior of both shear (G) and bulk (K) moduli at seismic frequencies. A recent upgrade of our experimental facility allows such measurements to be made without alteration of the driver/detector geometry, and uses an oscillating bending force rather than a bending moment, as previously described. The torsional and flexural tests were conducted in a gas apparatus at 200 MPa confining pressure, with oscillation periods ranging between 1 and 1000 s, during slow staged-cooling from 1300 to 25°C. Shear modulus and associated dissipation data are consistent with those for melt-bearing olivine specimens previously tested in torsion, with a pronounced dissipation peak superimposed on high-temperature background within the 1-1000 s observational window at temperatures of 1100-1200°C. A filament elongation model relates the observed flexural measurements to the variations along the experimental assembly of the complex Young's modulus (E*), bending moment and diametral moment of inertia. With E* given by 1/E*=1/(3G*) + 1/(9K*), and the complex shear modulus (G*) derived from torsional oscillation, any relaxation of K can be identified. Preliminary modeling shows that the viscoelastic properties in flexure are broadly consistent with those expected from the shear-mode viscoelasticity with anharmonic (real) values of K. However, some discrepancies between modeled results and flexure data at super-solidus temperatures require further investigation of possible differences in shear modulus relaxation between the torsional and flexural modes, and of potential relaxation of the bulk modulus through stress-induced changes in melt redistribution and
Commuting patterns of workers in a village of Barddhaman district, West Bengal
Directory of Open Access Journals (Sweden)
Bhaswati Mondal
2015-06-01
Full Text Available Commuting helps to keep balance between residence and workplace of workers. With growing accessibility and connectivity, the importance of commuting is increasing all over the world. It is becoming a major substitute to migration. In commute-studies, commute-pattern is an important chapter. It highlights commuters’ directions of movement, distance they cover, modes of transport they use, the time they take to commute, etc. Unlike the urban-based commute pattern, commute pattern in rural areas are relatively an under-researched issue. In fact, traditionally rural people are thought to carry a sedentary lifestyle. Using primary data, this study aims to explore the commute patterns of rural workers located in the village of Gandharbapur of Barddhaman district of West Bengal, India. All the commuters were found to be engaged in non-farm work. Commuters stem from two major groups. One group of commuters is accumulated farm-income induced. They possess sufficient agricultural land. Investing their surplus farm-income, they have established non-farm works. The second group of commuters is poverty-driven. They are landless poor or are marginal farmers and to escape poverty, they have slipped into these works. Located beyond the suburban area (Memari being the nearest town, most commuters commute to nearby rural areas. Due to non-availability of public transport, women commute less than men do. Regular-paid government employees commute longer than other workers commute. The article concludes with a summary of findings and recommendations for further research.
Energy Technology Data Exchange (ETDEWEB)
Schellekens, H.
1989-05-01
After showing the extended experience of Holec with vacuum disconnectors, the difficulties encountered in developing the type SVS vacuum bottle are indicated. The implications of demands imposed on price and dimensions are translated into design features. The function and the design of the getter is explained to show how Holec guarantees a 20 year approved vacuum in the bottle. Finally, the results of switching tests are mentioned to explain the reliability and capability of the new disconnector. 12 figs.
Asphalt mix characterization using dynamic modulus and APA testing.
2005-11-01
final report summarizes two research efforts related to asphalt mix characterization: dynamic modulus and Asphalt Pavement Analyzer testing. One phase of the research consisted of a laboratory-based evaluation of dynamic modulus of Oregon dense-grade...
Commuting behavior of western U.S. residents
Energy Technology Data Exchange (ETDEWEB)
Caviglia, J. [Tennessee Univ., Knoxville, TN (United States)]|[Oak Ridge National Lab., TN (United States)
1996-06-01
Estimation and interpretation of commutes to work has been studied extensively with respect to gender, race, and income. While the literature is extensive in these areas, there has been little research on regional differences between US states and territories. Since data which reports the commute to work is in average minutes, the distance traveled is estimated using estimates of the distance between home and work county centroids. The models differ in estimation of in-county commutes. The first assumes that the commute is equal to the radius of the county and the second estimates the commute as a weighted distance based on place location. Two data sets are compared, US National Guard data and US census data. Goal of this paper is to make conclusions about the commuting behavior of western residents through the use of these estimates, and therefore to provide a estimation method for distance commutes which can be used in further research. It is concluded that the radius method of estimation may be an over estimation, in particular in the western states. Since the non-western states are generally more homogeneously populated, this overestimation is not observed. It is recommended that the place location method be used for similar research, in particular studies dealing with western states. Suggestions are made for further research and recommendations are made for the US Army National Guard in regards to recruiting.
Nondestructive Measurement of Dynamic Modulus for Cellulose Nanofibril Films
Yan Qing; Robert J. Ross; Zhiyong Cai; Yiqiang Wu
2013-01-01
Nondestructive evaluation of cellulose nanofibril (CNF) films was performed using cantilever beam vibration (CBV) and acoustic methods to measure dynamic modulus. Static modulus was tested using tensile tension method. Correlation analysis shows the data measured by CBV has little linear relationship with static modulus, possessing a correlation coefficient (R
Modelling the relation between income and commuting distance
DEFF Research Database (Denmark)
Carra, Giulia; Mulalic, Ismir; Fosgerau, Mogens
2016-01-01
We discuss the distribution of commuting distances and its relation to income. Using data from Denmark, the UK and the USA, we show that the commuting distance is (i) broadly distributed with a slow decaying tail that can be fitted by a power law with exponent γ ≈ 3 and (ii) an average growing...... of the worker and decreases with the wage. The predicted distribution of commuting distances decays as 1/r3 and is independent of the distribution of the quality of jobs. We find our alternative model to be in agreement with our data. This type of approach opens new perspectives for the modelling of mobility....
Mechanism For Adjustment Of Commutation Of Brushless Motor
Schaefer, Richard E.
1995-01-01
Mechanism enables adjustment of angular position of set of Hall-effect devices that sense instantaneous shaft angle of brushless dc motor. Outputs of sensors fed to commutation circuitry. Measurement of shaft angle essential for commutation; that is, application of voltage to stator windings must be synchronized with shaft angle. To obtain correct angle measurement for commutation, Hall-effect angle sensors positioned at proper reference angle. The present mechanism accelerates adjustment procedure and makes it possible to obtain more accurate indication of minimum-current position because it provides for adjustment while motor running.
A remark on generalized commutation relation and subnormality
Directory of Open Access Journals (Sweden)
Jerzy Bartłomiej Stochel
2006-01-01
Full Text Available Tillmann [Tillmann H. G., Zur Eindeutigkeit der Losungen der quanten mechanischen vertauschungrelationen, Acta Sci. Math. (Szeged 24 (1963, 258-270] proved that every operator \\(A\\ which fulfils the canonical commutation relation \\(A^{*}A - AA^{*} = Id\\ is an orthogonal sum of canonical creation operators. We extend this result for operators which fulfil generalized commutation relation \\[A^{*}A - AA^{*}= E^2,\\text{ where }EA = AE.\\] In addition, some inequalities which are helpful in describing analytic vectors of operators \\(A^{*}A\\, where \\(A\\ fulfils the generalized commutation relation, are established.
Non-Commutative Mechanics in Mathematical & in Condensed Matter Physics
Directory of Open Access Journals (Sweden)
Peter A. Horváthy
2006-12-01
Full Text Available Non-commutative structures were introduced, independently and around the same time, in mathematical and in condensed matter physics (see Table 1. Souriau's construction applied to the two-parameter central extension of the planar Galilei group leads to the ''exotic'' particle, which has non-commuting position coordinates. A Berry-phase argument applied to the Bloch electron yields in turn a semiclassical model that has been used to explain the anomalous/spin/optical Hall effects. The non-commutative parameter is momentum-dependent in this case, and can take the form of a monopole in momentum space.
Dynamic modulus of nanosilica modified porous asphalt
Arshad, A. K.; Masri, K. A.; Ahmad, J.; Samsudin, M. S.
2017-11-01
Porous asphalt (PA) is a flexible pavement layer with high interconnected air void contents and constructed using open-graded aggregates. Due to high temperature environment and increased traffic volume in Malaysia, PA may have deficiencies particularly in rutting and stiffness of the mix. A possible way to improve these deficiencies is to improve the asphalt binder used. Binder is normally modified using polymer materials to improve its properties. However, nanotechnology presently is being gradually used for asphalt modification. Nanosilica (NS), a byproduct of rice husk and palm oil fuel ash is used as additive in this study. The aim of this study is to enhance the rutting resistance and stiffness performance of PA using NS. This study focused on the performance of PA in terms of dynamic modulus with the addition of NS modified binder to produce better and more durable PA. From the result of Dynamic SPT Test, it shows that the addition of NS was capable in enhancing the stiffness and rutting resistance of PA. The addition of NS also increase the dynamic modulus value of PA by 50%.
Microfabricated triggered vacuum switch
Roesler, Alexander W [Tijeras, NM; Schare, Joshua M [Albuquerque, NM; Bunch, Kyle [Albuquerque, NM
2010-05-11
A microfabricated vacuum switch is disclosed which includes a substrate upon which an anode, cathode and trigger electrode are located. A cover is sealed over the substrate under vacuum to complete the vacuum switch. In some embodiments of the present invention, a metal cover can be used in place of the trigger electrode on the substrate. Materials used for the vacuum switch are compatible with high vacuum, relatively high temperature processing. These materials include molybdenum, niobium, copper, tungsten, aluminum and alloys thereof for the anode and cathode. Carbon in the form of graphitic carbon, a diamond-like material, or carbon nanotubes can be used in the trigger electrode. Channels can be optionally formed in the substrate to mitigate against surface breakdown.
Insulation vacuum and beam vacuum overpressure release
Parma, V
2009-01-01
There is evidence that the incident of 19th September caused a high pressure build-up inside the cryostat insulation vacuum which the existing overpressure devices could not contain. As a result, high longitudinal forces acting on the insulation vacuum barriers developed and broke the floor and the floor fixations of the SSS with vacuum barriers. The consequent large longitudinal displacements of the SSS damaged chains of adjacent dipole cryo-magnets. Estimates of the helium mass flow and the pressure build- up experienced in the incident are presented together with the pressure build-up for an even more hazardous event, the Maximum Credible Incident (MCI). The strategy of limiting the maximum pressure by the installation of addition pressure relieve devices is presented and discussed. Both beam vacuum lines were ruptured during the incident in sector 3-4 giving rise to both mechanical damage and pollution of the system. The sequence, causes and effects of this damage will be briefly reviewed. We will then an...
Active commuting and perceptions of the route environment: A longitudinal analysis
Panter, Jenna; Griffin, Simon; Ogilvie, David
2014-01-01
Objective To assess associations between changes in perceptions of the environment en route to work and changes in active commuting. Methods 655 commuters in Cambridge, UK reported perceptions of their commuting route and past-week commuting trips in postal questionnaires in 2009 and 2010. Associations between changes in route perceptions and changes in time spent walking and cycling, proportion of car trips, and switching to or from the car on the commute were modelled using multivariable re...
Commutative algebra with a view toward algebraic geometry
Eisenbud, David
1995-01-01
Commutative Algebra is best understood with knowledge of the geometric ideas that have played a great role in its formation, in short, with a view towards algebraic geometry. The author presents a comprehensive view of commutative algebra, from basics, such as localization and primary decomposition, through dimension theory, differentials, homological methods, free resolutions and duality, emphasizing the origins of the ideas and their connections with other parts of mathematics. Many exercises illustrate and sharpen the theory and extended exercises give the reader an active part in complementing the material presented in the text. One novel feature is a chapter devoted to a quick but thorough treatment of Grobner basis theory and the constructive methods in commutative algebra and algebraic geometry that flow from it. Applications of the theory and even suggestions for computer algebra projects are included. This book will appeal to readers from beginners to advanced students of commutative algebra or algeb...
Simplicity and maximal commutative subalgebras of twisted generalized Weyl algebras
DEFF Research Database (Denmark)
Hartwig, J.T.; Öinert, Per Johan
2013-01-01
In this paper we prove three theorems about twisted generalized Weyl algebras (TGWAs). First, we show that each non-zero ideal of a TGWA has non-zero intersection with the centralizer of the distinguished subalgebra R . This is analogous to earlier results known to hold for crystalline graded rings....... Second, we give necessary and sufficient conditions for the centralizer of R to be commutative (hence maximal commutative), generalizing a result by V. Mazorchuk and L. Turowska. And third, we generalize results by D.A. Jordan and V. Bavula on generalized Weyl algebras by giving necessary and sufficient...... conditions for certain TGWAs to be simple, in the case when R is commutative. We illustrate our theorems by considering some special classes of TGWAs and providing concrete examples. We also discuss how simplicity of a TGWA is related to the maximal commutativity of R and the (non-)existence of non...
Strong Planck constraints on braneworld and non-commutative inflation
Energy Technology Data Exchange (ETDEWEB)
Calcagni, Gianluca [Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid (Spain); Kuroyanagi, Sachiko; Ohashi, Junko; Tsujikawa, Shinji, E-mail: calcagni@iem.cfmac.csic.es, E-mail: skuro@rs.tus.ac.jp, E-mail: j1211703@ed.tus.ac.jp, E-mail: shinji@rs.kagu.tus.ac.jp [Department of Physics, Faculty of Science, Tokyo University of Science, 1-3, Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)
2014-03-01
We place observational likelihood constraints on braneworld and non-commutative inflation for a number of inflaton potentials, using Planck, WMAP polarization and BAO data. Both braneworld and non-commutative scenarios of the kind considered here are limited by the most recent data even more severely than standard general-relativity models. At more than 95 % confidence level, the monomial potential V(φ)∝φ{sup p} is ruled out for p ≥ 2 in the Randall-Sundrum (RS) braneworld cosmology and, for p > 0, also in the high-curvature limit of the Gauss-Bonnet (GB) braneworld and in the infrared limit of non-commutative inflation, due to a large scalar spectral index. Some parameter values for natural inflation, small-varying inflaton models and Starobinsky inflation are allowed in all scenarios, although some tuning is required for natural inflation in a non-commutative spacetime.
Interactions Between Representation Ttheory, Algebraic Topology and Commutative Algebra
Pitsch, Wolfgang; Zarzuela, Santiago
2016-01-01
This book includes 33 expanded abstracts of selected talks given at the two workshops "Homological Bonds Between Commutative Algebra and Representation Theory" and "Brave New Algebra: Opening Perspectives," and the conference "Opening Perspectives in Algebra, Representations, and Topology," held at the Centre de Recerca Matemàtica (CRM) in Barcelona between January and June 2015. These activities were part of the one-semester intensive research program "Interactions Between Representation Theory, Algebraic Topology and Commutative Algebra (IRTATCA)." Most of the abstracts present preliminary versions of not-yet published results and cover a large number of topics (including commutative and non commutative algebra, algebraic topology, singularity theory, triangulated categories, representation theory) overlapping with homological methods. This comprehensive book is a valuable resource for the community of researchers interested in homological algebra in a broad sense, and those curious to learn the latest dev...
Non-commutative spheres and numerical quantum mechanics
Arveson, W
1992-01-01
We discuss some basic issues that arise when one attempts to model quantum mechanical systems on a computer, and we describe the mathematical structure of the resulting discretized cannonical commutation relations.
A review of non-commutative gauge theories
Indian Academy of Sciences (India)
-commutative space-time operators is reviewed. Examples of 4 theory and QED are then discussed. Problems of extending the theories to () gauge theories and arbitrary charges in QED are considered. Construction of standard model ...
Commuting, Externalities, and the Geographical Sizes of Metropolitan Areas
Bode, Eckhardt
2006-01-01
The paper proposes an econometric approach for quantifying jointly the geographical scope of commuting as well as the various forms of agglomeration economies originating from metropolitan centers. Adopting an urban economics perspective, and using land prices to measure their aggregate effects, the approach estimates the geographical reach of commuting and urban externalities from a hierarchical system of gradient functions. The results for West German NUTS3 regions indicate that metropolita...
What interventions increase commuter cycling? A systematic review.
Stewart, Glenn; Anokye, Nana Kwame; Pokhrel, Subhash
2015-08-14
To identify interventions that will increase commuter cycling. All settings where commuter cycling might take place. Adults (aged 18+) in any country. Individual, group or environmental interventions including policies and infrastructure. A wide range of 'changes in commuter cycling' indicators, including frequency of cycling, change in workforce commuting mode, change in commuting population transport mode, use of infrastructure by defined populations and population modal shift. 12 studies from 6 countries (6 from the UK, 2 from Australia, 1 each from Sweden, Ireland, New Zealand and the USA) met the inclusion criteria. Of those, 2 studies were randomised control trials and the remainder preintervention and postintervention studies. The majority of studies (n=7) evaluated individual-based or group-based interventions and the rest environmental interventions. Individual-based or group-based interventions in 6/7 studies were found to increase commuter cycling of which the effect was significant in only 3/6 studies. Environmental interventions, however, had small but positive effects in much larger but more difficult to define populations. Almost all studies had substantial loss to follow-up. Despite commuter cycling prevalence varying widely between countries, robust evidence of what interventions will increase commuter cycling in low cycling prevalence nations is sparse. Wider environmental interventions that make cycling conducive appear to reach out to hard to define but larger populations. This could mean that environmental interventions, despite their small positive effects, have greater public health significance than individual-based or group-based measures because those interventions encourage a larger number of people to integrate physical activity into their everyday lives. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Associations between active commuting and physical and mental wellbeing.
Humphreys, David K; Goodman, Anna; Ogilvie, David
2013-08-01
To examine whether a relationship exists between active commuting and physical and mental wellbeing. In 2009, cross-sectional postal questionnaire data were collected from a sample of working adults (aged 16 and over) in the Commuting and Health in Cambridge study. Travel behaviour and physical activity were ascertained using the Recent Physical Activity Questionnaire (RPAQ) and a seven-day travel-to-work recall instrument from which weekly time spent in active commuting (walking and cycling) was derived. Physical and mental wellbeing were assessed using the Medical Outcomes Study Short Form survey (SF-8). Associations were tested using multivariable linear regression. An association was observed between physical wellbeing (PCS-8) score and time spent in active commuting after adjustment for other physical activity (adjusted regression coefficients 0.48, 0.79 and 1.21 for 30-149 min/week, 150-224 min/week and ≥ 225 min/week respectively versus actively commuting is associated with higher levels of physical wellbeing. Longitudinal studies should examine the contribution of changing levels of active commuting and other forms of physical activity to overall health and wellbeing. Copyright © 2013 Elsevier Inc. All rights reserved.
Young's Modulus of bilayer Silicene Nanoribbons
Meza-Montes, Lilia; Chávez-Castillo, M. R.; Rodríguez-Meza, M. A.
Mechanical properties of Silicene Nanoribbons (SNRs) are determined by their width and chirality, and can be also be modified by the presence of vacancy defects. In the case of bilayer SNRs, interlayer interactions influence its physical properties. We report results, at room temperature, on the Young's Modulus (YM) of pristine and monovacancy defective bilayers of SNRs. Molecular dynamics simulations were performed using the EDIP potential. YM increases with SNRs length, depends on chirality, the number and location of vacancies. Distance between layers is also important. These results are discussed in terms of missing bonds. Atomic stress distributions for defective bilayer SNRs show a larger stress concentration around the vacancy defect. Besides, if only the second layer has a mono-vacancy at its center, a larger stress concentration is observed on the atom located just below the vacancy defect. Thus, the bilayer structure carries less strain and it can be easily deformed. Partially supported by VIEP-BUAP, Mexico.
On the continuity of the commutative limit of the 4d N=4 non-commutative super Yang–Mills theory
Directory of Open Access Journals (Sweden)
Masanori Hanada
2015-03-01
Full Text Available We study the commutative limit of the non-commutative maximally supersymmetric Yang–Mills theory in four dimensions (N=4 SYM, where non-commutativity is introduced in the two spacelike directions. The commutative limits of non-commutative spaces are important in particular in the applications of non-commutative spaces for regularisation of supersymmetric theories (such as the use of non-commutative spaces as alternatives to lattices for supersymmetric gauge theories and interpretations of some matrix models as regularised supermembrane or superstring theories, which in turn can play a prominent role in the study of quantum gravity via the gauge/gravity duality. In general, the commutative limits are known to be singular and non-smooth due to UV/IR mixing effects. We give a direct proof that UV effects do not break the continuity of the commutative limit of the non-commutative N=4 SYM to all order in perturbation theory, including non-planar contributions. This is achieved by establishing the uniform convergence (with respect to the non-commutative parameter of momentum integrals associated with all Feynman diagrams appearing in the theory, using the same tools involved in the proof of finiteness of the commutative N=4 SYM.
Hu, Jiazhong; Chen, Wenlan; Vendeiro, Zachary; Urvoy, Alban; Braverman, Boris; Vuletić, Vladan
2017-11-01
We investigate the generation of entanglement (spin squeezing) in an optical-transition atomic clock through the coupling to an optical cavity in its vacuum state. We show that if each atom is prepared in a superposition of the ground state and a long-lived electronic excited state, and viewed as a spin-1/2 system, then the collective vacuum light shift entangles the atoms, resulting in a squeezed distribution of the ensemble collective spin, without any light applied. This scheme reveals that even an electromagnetic vacuum can constitute a useful resource for entanglement and quantum manipulation. By rotating the spin direction while coupling to the vacuum, the scheme can be extended to implement two-axis twisting resulting in stronger squeezing.
2016-01-01
This comprehensive, standard work has been updated to remain an important resource for all those needing detailed knowledge of the theory and applications of vacuum technology. With many numerical examples and illustrations to visualize the theoretical issues.
Federal Laboratory Consortium — Located near the K-Basins (see K-Basins link) in Hanford's 100 Area is a facility called the Cold Vacuum Drying Facility (CVDF).Between 2000 and 2004, workers at the...
... the birth canal. The vacuum uses a soft plastic cup that attaches to the baby's head with suction. ... a numbing medicine placed in the vagina. The plastic cup will be placed on the baby's head. Then, ...
CERN. Geneva
2001-01-01
A short introduction for some basic facts and equations. Subsquently, discussion about: Building blocks of an ultrahigh vacuum system - Various types of pumps required to reach uhv and methods to reduce these effects - Outgassing phenomena induced by the presence of a particle beam and the most common methods to reduce these effects It will be given some practical examples from existing CERN accelerators and discuss the novel features of the future LHC vacuum system.
Whitaker, Jerry
2012-01-01
Providing examples of applications, Power Vacuum Tubes Handbook, Third Edition examines the underlying technology of each type of power vacuum tube device in common use today. The author presents basic principles, reports on new development efforts, and discusses implementation and maintenance considerations. Supporting mathematical equations and extensive technical illustrations and schematic diagrams help readers understand the material. Translate Principles into Specific Applications This one-stop reference is a hands-on guide for engineering personnel involved in the design, specification,
Directory of Open Access Journals (Sweden)
Daywitt W. C.
2009-04-01
Full Text Available Both the big-bang and the quasi-steady-state cosmologies originate in some type of Planck state. This paper presents a new cosmological theory based on the Planck- vacuum negative-energy state, a state consisting of a degenerate collection of negative- energy Planck particles. A heuristic look at the Einstein field equation provides a con- vincing argument that such a vacuum state could provide a theoretical explanation for the visible universe.
Commuting behaviour and urban form: a longitudinal study of a polycentric urban region in Denmark
DEFF Research Database (Denmark)
Grunfelder, Julien; Nielsen, Thomas Alexander Sick
2012-01-01
This paper is an empirical investigation of the relation between urban form and commuting behaviour in a polycentric urban region. It explores to what extent urban form and location variables help to explain commuting time, distance and mode based on an empirical case, East Jutland, which....... For instance, two of the important findings are that the distance to the closest urban centre is an important factor which affects the three selected aspects of commuting, while the distance from the residence to the closest large city (i.e. second-ranked city) is associated with a relatively short commuting...... selected aspects of commuting. However, urban form variables have greater explanatory power in explaining commuting modes than commuting time and commuting distance. No general trends in commuting were detectable from the data. Finally, the empirical findings revealed specificities of the case study...
Proof that Casimir force does not originate from vacuum energy
Directory of Open Access Journals (Sweden)
Hrvoje Nikolić
2016-10-01
Full Text Available We present a simple general proof that Casimir force cannot originate from the vacuum energy of electromagnetic (EM field. The full QED Hamiltonian consists of 3 terms: the pure electromagnetic term Hem, the pure matter term Hmatt and the interaction term Hint. The Hem-term commutes with all matter fields because it does not have any explicit dependence on matter fields. As a consequence, Hem cannot generate any forces on matter. Since it is precisely this term that generates the vacuum energy of EM field, it follows that the vacuum energy does not generate the forces. The misleading statements in the literature that vacuum energy generates Casimir force can be boiled down to the fact that Hem attains an implicit dependence on matter fields by the use of the equations of motion and to the illegitimate treatment of the implicit dependence as if it was explicit. The true origin of the Casimir force is van der Waals force generated by Hint.
A constrained modulus reconstruction technique for breast cancer assessment.
Samani, A; Bishop, J; Plewes, D B
2001-09-01
A reconstruction technique for breast tissue elasticity modulus is described. This technique assumes that the geometry of normal and suspicious tissues is available from a contrast-enhanced magnetic resonance image. Furthermore, it is assumed that the modulus is constant throughout each tissue volume. The technique, which uses quasi-static strain data, is iterative where each iteration involves modulus updating followed by stress calculation. Breast mechanical stimulation is assumed to be done by two compressional rigid plates. As a result, stress is calculated using the finite element method based on the well-controlled boundary conditions of the compression plates. Using the calculated stress and the measured strain, modulus updating is done element-by-element based on Hooke's law. Breast tissue modulus reconstruction using simulated data and phantom modulus reconstruction using experimental data indicate that the technique is robust.
Interfacial Modulus Mapping during Structural Transformation in Shape Memory Alloys
Wan, Jianfeng; Cui, Shushan; Zhang, Jihua; Rong, Yonghua
2017-10-01
Through the modified phase-field model the local soft mode mechanism of nucleation during martensitic transformation was confirmed in shape memory alloys. It was discovered that the modulus loss (8 pct) depended on the martensitic nucleation exceeding the loss (1 pct) during the martensitic growth. The elastic modulus and the stress across the martensite/parent interface differed from those across the martensitic twin boundary. The modulus losses in systems with three variants, two variants, and one variant were compared.
The active commuting route environment scale (ACRES: development and evaluation
Directory of Open Access Journals (Sweden)
Stigell Erik
2010-07-01
Full Text Available Abstract Background Route environments can be a potentially important factor in influencing people's behaviours in relation to active commuting. To better understand these possible relationships, assessments of route environments are needed. We therefore developed a scale; the Active Commuting Route Environment Scale (ACRES, for the assessment of bicyclists' and pedestrians' perceptions of their commuting route environments. Here we will report on the development and the results of validity and reliability assessments thereof. Methods Active commuters (n = 54 were recruited when they bicycled in Stockholm, Sweden. Traffic planning and environmental experts from the Municipality of Stockholm were assembled to form an expert panel (n = 24. The active commuters responded to the scale on two occasions, and the expert panel responded to it once. To test criterion-related validity, differences in ratings of the inner urban and suburban environments of Greater Stockholm were compared between the experts and the commuters. Furthermore, four items were compared with existing objective measures. Test-retest reproducibility was assessed with three types of analysis: order effect, typical error and intraclass correlation. Results There was a concordance in sizes and directions of differences in ratings of inner urban and suburban environments between the experts and the commuters. Furthermore, both groups' ratings were in line with existing objectively measured differences between the two environmental settings. Order effects between test and retest were observed in 6 of 36 items. The typical errors ranged from 0.93 to 2.54, and the intraclass correlation coefficients ranged from 'moderate' (0.42 to 'almost perfect' (0.87. Conclusions The ACRES was characterized by considerable criterion-related validity and reasonable test-retest reproducibility.
Thermal-vacuum facility with in-situ mechanical loading. [for testing space construction materials
Tennyson, R. C.; Hansen, J. S.; Holzer, R. P.; Uffen, B.; Mabson, G.
1978-01-01
The paper describes a thermal-vacuum space simulator used to assess property changes of fiber-reinforced polymer composite systems. The facility can achieve a vacuum of approximately .0000001 torr with temperatures ranging from -200 to +300 F. Some preliminary experimental results are presented for materials subjected to thermal loading up to 200 F. The tests conducted include the evaluation of matrix modulus and strength, coefficients of thermal expansion, and fracture toughness. Though the experimental program is at an early stage, the data appear to indicate that these parameters are influenced by hard vacuum.
Active commuting to school: How far is too far?
LENUS (Irish Health Repository)
Nelson, Norah M
2008-01-01
ABSTRACT: BACKGROUND: Walking and cycling to school provide a convenient opportunity to incorporate physical activity into an adolescent\\'s daily routine. School proximity to residential homes has been identified as an important determinant of active commuting among children. The purpose of this study is to identify if distance is a barrier to active commuting among adolescents, and if there is a criterion distance above which adolescents choose not to walk or cycle. METHODS: Data was collected in 2003-05 from a cross-sectional cohort of 15-17 yr old adolescents in 61 post primary schools in Ireland. Participants self-reported distance, mode of transport to school and barriers to active commuting. Trained researchers took physical measurements of height and weight. The relation between mode of transport, gender and population density was examined. Distance was entered into a bivariate logistic regression model to predict mode choice, controlling for gender, population density socio-economic status and school clusters. RESULTS: Of the 4013 adolescents who participated (48.1% female, mean age 16.02 +\\/- 0.661), one third walked or cycled to school. A higher proportion of males than females commuted actively (41.0 vs. 33.8%, chi2 (1) = 22.21, p < 0.001, r = -0.074). Adolescents living in more densely populated areas had greater odds of active commuting than those in the most sparsely populated areas (chi2 (df = 3) = 839.64, p < 0.001). In each density category, active commuters travelled shorter distances to school. After controlling for gender and population density, a 1-mile increase in distance decreased the odds of active commuting by 71% (chi2 (df = 1) = 2591.86, p < 0.001). The majority of walkers lived within 1.5 miles and cyclists within 2.5 miles. Over 90% of adolescents who perceived distance as a barrier to active commuting lived further than 2.5 miles from school. CONCLUSION: Distance is an important perceived barrier to active commuting and a predictor
Geometric properties of commutative subalgebras of partial differential operators
Zheglov, A. B.; Kurke, H.
2015-05-01
We investigate further algebro-geometric properties of commutative rings of partial differential operators, continuing our research started in previous articles. In particular, we start to explore the simplest and also certain known examples of quantum algebraically completely integrable systems from the point of view of a recent generalization of Sato's theory, developed by the first author. We give a complete characterization of the spectral data for a class of 'trivial' commutative algebras and strengthen geometric properties known earlier for a class of known examples. We also define a kind of restriction map from the moduli space of coherent sheaves with fixed Hilbert polynomial on a surface to an analogous moduli space on a divisor (both the surface and the divisor are part of the spectral data). We give several explicit examples of spectral data and corresponding algebras of commuting (completed) operators, producing as a by-product interesting examples of surfaces that are not isomorphic to spectral surfaces of any (maximal) commutative ring of partial differential operators of rank one. Finally, we prove that any commutative ring of partial differential operators whose normalization is isomorphic to the ring of polynomials k \\lbrack u,t \\rbrack is a Darboux transformation of a ring of operators with constant coefficients. Bibliography: 39 titles.
Fitness, Fatness and Active School Commuting among Liverpool Schoolchildren.
Noonan, Robert J; Boddy, Lynne M; Knowles, Zoe R; Fairclough, Stuart J
2017-08-31
This study investigated differences in health outcomes between active and passive school commuters, and examined associations between parent perceptions of the neighborhood environment and active school commuting (ASC). One hundred-ninety-four children (107 girls), aged 9-10 years from ten primary schools in Liverpool, England, participated in this cross-sectional study. Measures of stature, body mass, waist circumference and cardiorespiratory fitness (CRF) were taken. School commute mode (active/passive) was self-reported and parents completed the neighborhood environment walkability scale for youth. Fifty-three percent of children commuted to school actively. Schoolchildren who lived in more deprived neighborhoods perceived by parents as being highly connected, unaesthetic and having mixed land-use were more likely to commute to school actively (p < 0.05). These children were at greatest risk of being obese and aerobically unfit(p < 0.01). Our results suggest that deprivation may explain the counterintuitive relationship between obesity, CRF and ASC in Liverpool schoolchildren. These findings encourage researchers and policy makers to be equally mindful of the social determinants of health when advocating behavioral and environmental health interventions. Further research exploring contextual factors to ASC, and examining the concurrent effect of ASC and diet on weight status by deprivation is needed.
Fitness, Fatness and Active School Commuting among Liverpool Schoolchildren
Directory of Open Access Journals (Sweden)
Robert J. Noonan
2017-08-01
Full Text Available This study investigated differences in health outcomes between active and passive school commuters, and examined associations between parent perceptions of the neighborhood environment and active school commuting (ASC. One hundred-ninety-four children (107 girls, aged 9–10 years from ten primary schools in Liverpool, England, participated in this cross-sectional study. Measures of stature, body mass, waist circumference and cardiorespiratory fitness (CRF were taken. School commute mode (active/passive was self-reported and parents completed the neighborhood environment walkability scale for youth. Fifty-three percent of children commuted to school actively. Schoolchildren who lived in more deprived neighborhoods perceived by parents as being highly connected, unaesthetic and having mixed land-use were more likely to commute to school actively (p < 0.05. These children were at greatest risk of being obese and aerobically unfit(p < 0.01. Our results suggest that deprivation may explain the counterintuitive relationship between obesity, CRF and ASC in Liverpool schoolchildren. These findings encourage researchers and policy makers to be equally mindful of the social determinants of health when advocating behavioral and environmental health interventions. Further research exploring contextual factors to ASC, and examining the concurrent effect of ASC and diet on weight status by deprivation is needed.
Vacuum induced photoresist outgassing
Waterman, Justin; Mbanaso, Chimaobi; Denbeaux, Gregory
2008-03-01
In order to continue the trend toward smaller feature sizes in lithography, new methods of lithography will be needed. A likely method for printing features 32 nm and smaller is extreme ultraviolet (EUV) lithography. EUV allows for features to be printed that are smaller than the current methods can achieve. However, outgassing of the photoresist is a concern for EUV lithography. The outgassed components can lead to contamination of the optics, degrading the reflectivity and hence lowering throughput of the exposure tools. Outgassing due to EUV exposure has been investigated by many groups. However, there were no complete investigations available of vacuum induced outgassing. In this paper, several methods were employed to investigate the outgassing due to vacuum. It was found that the vacuum induced outgassing outgassed a similar number of molecules as the outgassing due to EUV exposure. Furthermore, almost all of the outgassing was completed after about two minutes in vacuum. To mitigate the potential concern of outgassing due to vacuum causing contamination of optics, this work shows that photoresist coated silicon wafers only require about two minutes of pumping prior to insertion near the optics within EUV lithography tools.
Impact of Distance on Mode of Active Commuting in Chilean Children and Adolescents
Directory of Open Access Journals (Sweden)
Fernando Rodríguez-Rodríguez
2017-11-01
Full Text Available Active commuting could contribute to increasing physical activity. The objective of this study was to characterise patterns of active commuting to and from schools in children and adolescents in Chile. A total of 453 Chilean children and adolescents aged between 10 and 18 years were included in this study. Data regarding modes of commuting and commuting distance was collected using a validated questionnaire. Commuting mode was classified as active commuting (walking and/or cycling or non-active commuting (car, motorcycle and/or bus. Commuting distance expressed in kilometres was categorised into six subgroups (0 to 0.5, 0.6 to 1, 1.1 to 2, 2.1 to 3, 3.1 to 5 and >5 km. Car commuting was the main mode for children (to school 64.9%; from school 51.2% and adolescents (to school 50.2%; from school 24.7%. Whereas public bus commuting was the main transport used by adolescents to return from school. Only 11.0% and 24.8% of children and adolescents, respectively, walk to school. The proportion of children and adolescents who engage in active commuting was lower in those covering longer distances compared to a short distance. Adolescents walked to and from school more frequently than children. These findings show that non-active commuting was the most common mode of transport and that journey distances may influence commuting modes in children and adolescents.
Elastic modulus in the selection of interbody implants.
Heary, Robert F; Parvathreddy, Naresh; Sampath, Sujitha; Agarwal, Nitin
2017-06-01
The modulus of elasticity of an assortment of materials used in spinal surgery, as well as cortical and cancellous bones, is determined by direct measurements and plotting of the appropriate curves. When utilized in spine surgery, the stiffness of a surgical implant can affect its material characteristics. The modulus of elasticity, or Young's modulus, measures the stiffness of a material by calculating the slope of the material's stress-strain curve. While many papers and presentations refer to the modulus of elasticity as a reason for the choice of a particular spinal implant, no peer-reviewed surgical journal article has previously been published where the Young's modulus values of interbody implants have been measured. Materials were tested under pure compression at the rate of 2 mm/min. A maximum of 45 kilonewtons (kN) compressive force was applied. Stress-strain characteristics under compressive force were plotted and this plot was used to calculate the elastic modulus. The elastic modulus calculated for metals was more than 50 Gigapascals (GPa) and had significantly higher modulus values compared to poly-ether-ether-ketone (PEEK) materials and allograft bone. The data generated in this paper may facilitate surgeons to make informed decisions on their choices of interbody implants with specific attention to the stiffness of the implant chosen.
Estimate of K-functionals and modulus of smoothness constructed ...
Indian Academy of Sciences (India)
Using a generalized spherical mean operator, we define generalized modulus of smoothness in the space L k 2 ( R d ) . Based on the Dunkl operator we define Sobolev-type space and -functionals. The main result of the paper is the proof of the equivalence theorem for a -functional and a modulus of smoothness for the ...
Generalized Vector-Valued Sequence Spaces Defined by Modulus Functions
Directory of Open Access Journals (Sweden)
Işik Mahmut
2010-01-01
Full Text Available We introduce the vector-valued sequence spaces , , and , and , using a sequence of modulus functions and the multiplier sequence of nonzero complex numbers. We give some relations related to these sequence spaces. It is also shown that if a sequence is strongly -Cesàro summable with respect to the modulus function then it is -statistically convergent.
Bulk modulus of metals according to structureless pseudopotential ...
African Journals Online (AJOL)
structureless pseudopotential model was fully developed. The developed method was used to calculate the bulk modulus and kinetic energy contribution to the bulk modulus of 46 elemental metals. The results obtained were compared with experimental values and their variation with electron density parameter was studied ...
1997-01-01
Under a Space Act Agreement between the Kirby company and Lewis Research Center, NASA technology was applied to a commercial vacuum cleaner product line. Kirby engineers were interested in advanced operational concepts, such as particle flow behavior and vibration, critical factors to improve vacuum cleaner performance. An evaluation of the company 1994 home care system, the Kirby G4, led to the refinement of the new G5 and future models. Under the cooperative agreement, Kirby had access to Lewis' holography equipment, which added insight into how long a vacuum cleaner fan would perform, as well as advanced computer software that can simulate the flow of air through fans. The collaboration resulted in several successes including fan blade redesign and continuing dialogue on how to improve air-flow traits in various nozzle designs.
Multi-commutation in flow analysis: recent developments and applications.
Feres, Mário A; Fortes, Paula R; Zagatto, Elias A G; Santos, João L M; Lima, José L F C
2008-06-16
The concept of multi-commutation in flow analysis is revisited, and emphasis is given to recent methodological and applicative achievements. Multi-commutation is compatible with different flow patterns (unsegmented, segmented, pulsed, tandem) and amenable to concentration-oriented feedback mechanisms. Its exploitation has led to significant attainments mainly in relation to versatility of the flow system. Characteristics and potentialities of the multi-commuted flow systems are discussed, and guidelines for assisting methodological implementation are given. The number of applications has experienced remarkable increase during last years; therefore, the applicative part of this review is focused on the recent noteworthy applications, mainly in relation to environmental, agronomical, pharmaceutical, biological, food and industrial samples.
Non-topological non-commutativity in string theory
Guttenberg, Sebastian; Kreuzer, Maximilian; Rashkov, Radoslav
2007-01-01
Quantization of coordinates leads to the non-commutative product of deformation quantization, but is also at the roots of string theory, for which space-time coordinates become the dynamical fields of a two-dimensional conformal quantum field theory. Appositely, open string diagrams provided the inspiration for Kontsevich's solution of the long-standing problem of quantization of Poisson geometry by virtue of his formality theorem. In the context of D-brane physics non-commutativity is not limited, however, to the topolocial sector. We show that non-commutative effective actions still make sense when associativity is lost and establish a generalized Connes-Flato-Sternheimer condition through second order in a derivative expansion. The measure in general curved backgrounds is naturally provided by the Born--Infeld action and reduces to the symplectic measure in the topological limit, but remains non-singular even for degenerate Poisson structures. Analogous superspace deformations by RR--fields are also discus...
Optimization of polynomials in non-commuting variables
Burgdorf, Sabine; Povh, Janez
2016-01-01
This book presents recent results on positivity and optimization of polynomials in non-commuting variables. Researchers in non-commutative algebraic geometry, control theory, system engineering, optimization, quantum physics and information science will find the unified notation and mixture of algebraic geometry and mathematical programming useful. Theoretical results are matched with algorithmic considerations; several examples and information on how to use NCSOStools open source package to obtain the results provided. Results are presented on detecting the eigenvalue and trace positivity of polynomials in non-commuting variables using Newton chip method and Newton cyclic chip method, relaxations for constrained and unconstrained optimization problems, semidefinite programming formulations of the relaxations and finite convergence of the hierarchies of these relaxations, and the practical efficiency of algorithms.
Brown, I.
2013-12-16
The vacuum arc ion source has evolved into a more or less standard laboratory tool for the production of high-current beams of metal ions, and is now used in a number of different embodiments at many laboratories around the world. Applications include primarily ion implantation for material surface modification research, and good performance has been obtained for the injection of high-current beams of heavy-metal ions, in particular uranium, into particle accelerators. As the use of the source has grown, so also have the operational characteristics been improved in a variety of different ways. Here we review the principles, design, and performance of vacuum arc ion sources.
Energy Technology Data Exchange (ETDEWEB)
Hamada, Yuta [KEK Theory Center, IPNS, KEK, Tsukuba, Ibaraki (Japan); Yamada, Masatoshi [Kanazawa University, Institute for Theoretical Physics, Kanazawa (Japan)
2017-09-15
The null result in the LHC may indicate that the standard model is not drastically modified up to very high scales, such as the GUT/string scale. Having this in the mind, we suggest a novel leptogenesis scenario realized in the false vacuum of the Higgs field. If the Higgs field develops a large vacuum expectation value in the early universe, a lepton number violating process is enhanced, which we use for baryogenesis. To demonstrate the scenario, several models are discussed. For example, we show that the observed baryon asymmetry is successfully generated in the standard model with higher-dimensional operators. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Lorenci, V.A. de; Svaiter, N.F. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)
1996-11-01
It was investigated which mapping has to be used to compare measurements made in a rotating frame to those made in an inertial frame. Using a non-Galilean coordinate transformation, the creation-annihilation operators of a massive scalar field in the rotating frame are not the same as those of an inertial observer. This leads to a new vacuum state(a rotating vacuum) which is a superposition of positive and negative frequency Minkowski particles. Polarization effects in circular accelerators in the proper frame of the electron making a connection with the inertial frame point of view were analysed. 65 refs.
1964-01-01
Handbook of Vacuum Physics, Volume 3: Technology is a handbook of vacuum physics, with emphasis on the properties of miscellaneous materials such as mica, oils, greases, waxes, and rubber. Accurate modern tables of physical constants, properties of materials, laboratory techniques, and properties of commercial pumps, gauges, and leak detectors are presented. This volume is comprised of 12 chapters and begins with a discussion on pump oils, divided into rotary pump oils and vapor pump oils. The next chapter deals with the properties and applications of greases, including outgassing and vapor pr
Changes to urban form and commuting patterns: trends in two Danish city regions
DEFF Research Database (Denmark)
Nielsen, Thomas Alexander Sick
2015-01-01
This paper compares indicators of polycentricity in a monocentric (MUR) and a polycentric urban region (PUR) in Denmark at two points in time (1982 and 2002). It describes how population, jobs and commuting indicators of polycentricity develop and interact over time. Both the MUR and the PUR tend...... towards more balanced development. The increasing size of the main node in the PUR is the only deviation from the general trend. The general tendency towards a more polycentric regional structure was most marked in changing interaction and commuting patterns. Inter-urban commuting increased, while intra......-urban commuting decreased, leading to dispersion of commuters and a rapid increase in commuting across the region. Commuting distances were shortest in the polycentric region, but it also had the highest growth rates. In both regions, the balancing trend leads to a dispersal of commuting demand over...
Non-Commutative Homometry in the Dihedral Groups
Genuys, Grégoire
2017-01-01
The paper deals with the question of homometry in the dihedral groups $D_{n}$ of order $2n$. These groups have the specificity to be non-commutative. It leads to a new approach as compared as the one used in the traditional framework of the commutative group $ \\mathbb{Z}_{n}$. We give here a musical interpretation of homometry in $D_{12}$ using the well-known neo-Riemannian groups, some computational results concerning enumeration of homometric sets for small values of $n$, and some propertie...
Exotic Galilean Symmetry and Non-Commutative Mechanics
Directory of Open Access Journals (Sweden)
Peter A. Horváthy
2010-07-01
Full Text Available Some aspects of the ''exotic'' particle, associated with the two-parameter central extension of the planar Galilei group are reviewed. A fundamental property is that it has non-commuting position coordinates. Other and generalized non-commutative models are also discussed. Minimal as well as anomalous coupling to an external electromagnetic field is presented. Supersymmetric extension is also considered. Exotic Galilean symmetry is also found in Moyal field theory. Similar equations arise for a semiclassical Bloch electron, used to explain the anomalous/spin/optical Hall effects.
Powers of a product of commutators as products of squares
Directory of Open Access Journals (Sweden)
Alireza Abdollahi
2004-01-01
Full Text Available We prove that for any odd integer N and any integer n>0, the Nth power of a product of n commutators in a nonabelian free group of countable infinite rank can be expressed as a product of squares of 2n+1 elements and, for all such odd N and integers n, there are commutators for which the number 2n+1 of squares is the minimum number such that the Nth power of its product can be written as a product of squares. This generalizes a recent result of Akhavan-Malayeri.
Features of Synchronous Electronically Commutated Motors in Servomotor Operation Modes
Dirba, J.; Lavrinovicha, L.; Dobriyan, R.
2017-04-01
The authors consider the features and operation specifics of the synchronous permanent magnet motors and the synchronous reluctance motors with electronic commutation in servomotor operation modes. Calculation results show that mechanical and control characteristics of studied motors are close to a linear shape. The studied motor control is proposed to implement similar to phase control of induction servomotor; it means that angle θ (angle between vectors of the supply voltage and non-load electromotive force) or angle ɛ (angle between rotor direct axis and armature magnetomotive force axis) is changed. The analysis results show that synchronous electronically commutated motors could be used as servomotors.
Modular Theory, Non-Commutative Geometry and Quantum Gravity
Directory of Open Access Journals (Sweden)
Wicharn Lewkeeratiyutkul
2010-08-01
Full Text Available This paper contains the first written exposition of some ideas (announced in a previous survey on an approach to quantum gravity based on Tomita-Takesaki modular theory and A. Connes non-commutative geometry aiming at the reconstruction of spectral geometries from an operational formalism of states and categories of observables in a covariant theory. Care has been taken to provide a coverage of the relevant background on modular theory, its applications in non-commutative geometry and physics and to the detailed discussion of the main foundational issues raised by the proposal.
Technology handbook of vacuum physics
Beck, A H
2013-01-01
Handbook of Vacuum Physics, Volume 3: Technology is part of a series of publications that presents articles featuring the whole spectrum of vacuum physics. This particular volume presents materials that deal with technology concerns in vacuum mechanics. The first material talks about the utilization of ceramic materials in the construction of vacuum devices. The next paper details the application of vacuum physics in soldering and brazing process. The last article deals with the utilization of vacuum technology in high frequency heating. The book will be of great use to professionals involved
Associations between long commutes and subjective health complaints among railway workers in Norway.
Urhonen, Terhi; Lie, Arve; Aamodt, Geir
2016-12-01
Commuting is an important aspect of daily life for many employees, but there is little knowledge of how this affects individual commuters' health and well-being. The authors investigated the relationship between commuting and subjective health complaints, using data from a web-based questionnaire. In a sample of 2126 railway employees, 644 (30.3%) had long commute times. A 29-item inventory was used to measure the number and degree of the subjective health complaints. Those who commuted 60 min or more each way were characterized by significantly higher numbers and degrees of subjective health complaints compared with their peers with short commutes. The mean number of complaints was 7.5 among the former group and 6.4 for the latter group (p = 0.009). In a regression model, in which the authors controlled for age, gender, education, self-rated health, and coping, the employees with long commutes reported more complaints than those with short commutes. Significant associations were found between those with long commutes and the number and degree of incidences of self-reported musculoskeletal pain, pseudo-neurologic complaints, and gastrointestinal problems. Commuters who had had long commutes for more than 10 years reported more gastrointestinal and musculoskeletal complaints than those with long commutes for less than 2 years. Also, commuters with long commutes spent less time with their families and leisure activities compared with those with short commutes. The authors conclude that the association between long commute times and higher levels of subjective health complaints should attract the attention of transport planners, employers, and public health policymaker.
Associations between long commutes and subjective health complaints among railway workers in Norway
Directory of Open Access Journals (Sweden)
Terhi Urhonen
2016-12-01
Full Text Available Commuting is an important aspect of daily life for many employees, but there is little knowledge of how this affects individual commuters' health and well-being. The authors investigated the relationship between commuting and subjective health complaints, using data from a web-based questionnaire. In a sample of 2126 railway employees, 644 (30.3% had long commute times. A 29-item inventory was used to measure the number and degree of the subjective health complaints. Those who commuted 60 min or more each way were characterized by significantly higher numbers and degrees of subjective health complaints compared with their peers with short commutes. The mean number of complaints was 7.5 among the former group and 6.4 for the latter group (p = 0.009. In a regression model, in which the authors controlled for age, gender, education, self-rated health, and coping, the employees with long commutes reported more complaints than those with short commutes. Significant associations were found between those with long commutes and the number and degree of incidences of self-reported musculoskeletal pain, pseudo-neurologic complaints, and gastrointestinal problems. Commuters who had had long commutes for more than 10 years reported more gastrointestinal and musculoskeletal complaints than those with long commutes for less than 2 years. Also, commuters with long commutes spent less time with their families and leisure activities compared with those with short commutes. The authors conclude that the association between long commute times and higher levels of subjective health complaints should attract the attention of transport planners, employers, and public health policymaker.
The commuter family as a geographical adaptive strategy for the work-family balance
van der Klis, M.; Karsten, L.
2009-01-01
In this paper we raise the question of how commuter families create a work-family balance in a situation of incongruity of the geographical scales of work and family. Commuter families combine the work location of a commuting parent on the (inter)national scale, with the home-based parent's work
49 CFR 37.85 - Purchase or lease of new intercity and commuter rail cars.
2010-10-01
... rail cars. 37.85 Section 37.85 Transportation Office of the Secretary of Transportation TRANSPORTATION....85 Purchase or lease of new intercity and commuter rail cars. Amtrak or a commuter authority making a solicitation after August 25, 1990, to purchase or lease a new intercity or commuter rail car for use on the...
14 CFR 135.398 - Commuter category airplanes performance operating limitations.
2010-01-01
... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Commuter category airplanes performance... ON BOARD SUCH AIRCRAFT Airplane Performance Operating Limitations § 135.398 Commuter category airplanes performance operating limitations. (a) No person may operate a commuter category airplane unless...
20 CFR 704.102 - Commutation of payments to aliens and nonresidents.
2010-04-01
... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Commutation of payments to aliens and... LHWCA EXTENSIONS Defense Base Act § 704.102 Commutation of payments to aliens and nonresidents. Authority to commute payments to aliens and nonnationals who are not residents of the United States and...
1983-01-01
This is a cut-out of a LEP vacuum chamber for dipole magnets showing the beam channel and the pumping channel with the getter (NEG) strip and its insulating supports. A water pipe connected to the cooling channel can also be seen at the back.The lead radiation shield lining is also shown. See also 8305563X.
2007-01-01
"Modern physics has shown that the vacuum, previously thought of as a stated of total nothingness, is really a seething background of virtual particles springing in and out of eixstence until they can seize enough energy to materialize as "real" particles." (1,5 page)
CERN PhotoLab
1983-01-01
Final prototype for the LEP vacuum chamber, see 8305170 for more details. Here we see the strips of the NEG pump, providing "distributed pumping". The strips are made from a Zr-Ti-Fe alloy. By passing an electrical current, they were heated to 700 deg C.
CERN PhotoLab
1971-01-01
Some of the most important components of the vacuum system are shown. At the left, the rectangular box is a sputter-ion pump inside its bake-out oven. The assembly in the centre includes a sector valve, three roughing valves, a turbomolecular pump, a rotary backing pump and auxiliary equipment. At the right, the small elbow houses a Bayard-
Solving the {eta}-problem in hybrid inflation with Heisenberg symmetry and stabilized modulus
Energy Technology Data Exchange (ETDEWEB)
Antusch, Stefan; Dutta, Koushik; Kostka, Philipp M. [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, 80805 Muenchen (Germany); Bastero-Gil, Mar [Departamento de Fisica Teorica y del Cosmos and Centro Andaluz de Fisica de Particulas Elementales, Universidad de Granada, 19071 Granada (Spain); King, Steve F., E-mail: antusch@mppmu.mpg.de, E-mail: mbg@ugr.es, E-mail: koushik@mppmu.mpg.de, E-mail: sfk@hep.phys.soton.ac.uk, E-mail: kostka@mppmu.mpg.de [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom)
2009-01-15
We propose a class of models in which the {eta}-problem of supersymmetric hybrid inflation is resolved using a Heisenberg symmetry, where the associated modulus field is stabilized and made heavy with the help of the large vacuum energy during inflation without any fine-tuning. The proposed class of models is well motivated both from string theory considerations, since it includes the commonly encountered case of no-scale supergravity Kaehler potential, and from the perspective of particle physics since a natural candidate for the inflaton in this class of models is the right-handed sneutrino which is massless during the inflationary epoch, and subsequently acquires a large mass at the end of inflation. We study a specific example motivated by sneutrino hybrid inflation with no-scale supergravity in some detail, and show that the spectral index may lie within the latest WMAP range, while the tensor-to-scalar ratio is very small.
Furnace brazing under partial vacuum
Mckown, R. D.
1979-01-01
Brazing furnace utilizing partial-vacuum technique reduces tooling requirements and produces better bond. Benefit in that partial vacuum helps to dissociate metal oxides that inhibit metal flow and eliminates heavy tooling required to hold parts together during brazing.
Tritium handling in vacuum systems
Energy Technology Data Exchange (ETDEWEB)
Gill, J.T. [Monsanto Research Corp., Miamisburg, OH (United States). Mound Facility; Coffin, D.O. [Los Alamos National Lab., NM (United States)
1986-10-01
This report provides a course in Tritium handling in vacuum systems. Topics presented are: Properties of Tritium; Tritium compatibility of materials; Tritium-compatible vacuum equipment; and Tritium waste treatment.
Modulus of Elasticity and Thermal Expansion Coefficient of ITO Film
Energy Technology Data Exchange (ETDEWEB)
Carter, Austin D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Elhadj, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2016-06-24
The purpose of this experiment was to determine the modulus of elasticity (E) and thermal expansion coefficient (α) of RF sputtered Indium Tin Oxide (ITO) as a function of temperature (T), and to collect ITO film stress data. In order to accomplish that goal, the Toho FLX-2320-S thin film stress measurement machine was used to collect both single stress and stress-temperature data for ITO coated fused silica and sapphire substrates. The stress measurement function of the FLX-2320-S cannot be used to calculate the elastic modulus of the film because the Stoney formula incorporates the elastic modulus of the substrate, rather than of the film itself.
Active Commuting to School as a Source of Health Promotion ...
African Journals Online (AJOL)
user
and mobility challenges were excluded from the study. The selected students were provided with packets containing the consent forms to be completed by the students and their parents; and the active commuting questionnaire to be completed by the students. A total of 926 (84.2%) out of the 1100 students who received the ...
A new method of converter transformer protection without commutation failure
Zhang, Jiayu; Kong, Bo; Liu, Mingchang; Zhang, Jun; Guo, Jianhong; Jing, Xu
2018-01-01
With the development of AC / DC hybrid transmission technology, converter transformer as nodes of AC and DC conversion of HVDC transmission technology, its reliable safe and stable operation plays an important role in the DC transmission. As a common problem of DC transmission, commutation failure poses a serious threat to the safe and stable operation of power grid. According to the commutation relation between the AC bus voltage of converter station and the output DC voltage of converter, the generalized transformation ratio is defined, and a new method of converter transformer protection based on generalized transformation ratio is put forward. The method uses generalized ratio to realize the on-line monitoring of the fault or abnormal commutation components, and the use of valve side of converter transformer bushing CT current characteristics of converter transformer fault accurately, and is not influenced by the presence of commutation failure. Through the fault analysis and EMTDC/PSCAD simulation, the protection can be operated correctly under the condition of various faults of the converter.
On additive groups of associative and commutative rings ...
African Journals Online (AJOL)
The characterization of (A)CR-groups studied by Shalom Feigelstock [`Additive groups of commutative rings', Quaest. Math. 23 (2000), 241-245] is complemented. In particular, the theorem characterizing mixed ACR-groups is proved and numerous new examples of (A)CR-group are given. Abelian groups A such that any ...
Standards and Guidelines for Commuter Student Programs and Services.
NASPA Journal, 1986
1986-01-01
In describing standards and guidelines for commuter student programs and services, an analysis is provided of the mission, the program, multicultural programs and services, leadership and management, organization and administration, human resources, funding, facilities, legal responsibilities, equal opportunity, access and affirmative action,…
The spectral theory of commutative C*-algebras: the constructive ...
African Journals Online (AJOL)
... theory which expresses one's natural intuition of the notion involved, and then to establish various properties, leading up to the final result, by formal reasoning within these theories. Keywords: locale; commutative C*-algebra; spectrum; propositional geometric theory; constructive; Gelfand duality; Gelfand-Mazur theorem
A characterization of semiprojectivity for commutative C*-algebras
DEFF Research Database (Denmark)
Sørensen, Adam Peder Wie; Theil, Hannes
2012-01-01
Given a compact metric space X, we show that the commutative C*-algebra C(X) is semiprojective if and only if X is an absolute neighbourhood retract of dimension at most 1. This confirms a conjecture of Blackadar. Generalizing to the non-unital setting, we derive a characterization of semiproject...
African Women Commuter Traders in Nairobi in the First Decade ...
African Journals Online (AJOL)
This article investigates African women commuter trading activities in Nairobi in the first decade after World War One. Its findings derive mainly from a research project carried out in 1989-1996. The major source of data for the study was oral interviews with the women who traded in Nairobi during the years under study, ...
coincidentally commuting mappings in D-metric spaces
Directory of Open Access Journals (Sweden)
B. C. Dhage
2003-01-01
pairs of a single-valued and a multivalued coincidentally commuting mappings in D-metric spaces satisfying a certain generalized contraction condition. Our result generalizes more than a dozen known fixed-point theorems in D-metric spaces including those of Dhage (2000 and Rhoades (1996.
Exploratory mapping of commuter flows in England and Wales
DEFF Research Database (Denmark)
Nielsen, Thomas Alexander Sick; Hovgesen, Henrik Harder; Lassen, Claus
2005-01-01
and Birmingham. These are chosen for their size and differences in regional context. In the general analysis – at the country-wide scale - special emphasis is put on deriving a representation of the scale and the corridors of interaction from the relatively disaggregate data. A map of commuter flows in England...
Limits of commutative triangular systems on locally compact groups
Indian Academy of Sciences (India)
Keywords. Embeddable measures; triangular systems of measures; infinitesimally divisible measures; totally disconnected groups; real algebraic groups. 1. Introduction. Commutative triangular systems of probability measures on locally compact groups have been studied extensively and recently the embedding of the limit ...
A review of non-commutative gauge theories
Indian Academy of Sciences (India)
Abstract. Construction of quantum field theory based on operators that are functions of non- commutative space-time operators is reviewed. Examples of φ4 theory and QED are then discussed. Problems of extending the theories toSU´Nµ gauge theories and arbitrary charges in QED are consid- ered. Construction of ...
Preferences for housing, jobs, and commuting : A mixed logit analysis
Rouwendal, J.; Meijer, Erik
This paper reports stated preferences of Dutch workers for combinations of housing, employment, and commuting. The analysis uses standard logit models as well as mixed logit models. Estimation results offer insights into the relative importance of various aspects of housing, employment, and
Preferences for Housing, Jobs and Commuting: A Mixed Logit Analysis
Rouwendal, J.; Meijer, E.
2001-01-01
This paper reports stated preferences of Dutch workers for combinations of housing, employment, and commuting. The analysis uses standard logit models as well as mixed logit models. Estimation results offer insights into the relative importance of various aspects of housing, employment, and
Einstein–Podolski–Rosen paradox, non-commuting operator ...
Indian Academy of Sciences (India)
Einstein, Podolski and Rosen (EPR) have shown that any wavefunction (subject to the Schrödinger equation) can describe the physical reality completely, and any two observables associated with two non-commuting operators can have simultaneous reality. In contrast, quantum theory claims that the wavefunction can ...
Exploring characteristics and motives of long distance commuter cyclists
DEFF Research Database (Denmark)
Hansen, Karsten Bruun; Sick Nielsen, Thomas
2014-01-01
are very positive about their commute - pointing to positive experiences, better mood, and stress relief as experiences related to their cycle trip to work. Policy support should devote attention to unlocking the potential that may be embedded in individuals combining their exercise and travel time...
The M5-brane and non-commutative open strings
Bergshoeff, E.; Berman, D.S.; Schaar, J.P. van der; Sundell, P.
2001-01-01
The M-theory origin of non-commutative open-string theory is examined by investigating the M-theory 5-brane at near critical field strength. In particular, it is argued that the open-membrane metric provides the appropriate moduli when calculating the duality relations between M and II
A multipurpose switched reluctance motor with a series commutation buffer
Directory of Open Access Journals (Sweden)
L.A. Vasil'ev
2014-06-01
Full Text Available In this paper, a power-supply circuit for a multipurpose switched reluctance motor with a series commutation buffer is presented. It is shown that a series buffer improves output characteristics of multipurpose switched reluctance motors under supply from a single-phase circuit and also lifts necessity of switching capacitors according to the motor power supply modes.
Regenerative Snubber For GTO-Commutated SCR Inverter
Rippel, Wally E.; Edwards, Dean B.
1992-01-01
Proposed regenerative snubbing circuit substituted for dissipative snubbing circuit in inverter based on silicon controlled rectifiers (SCR's) commutated by gate-turn-off thyristor (GTO). Intended to reduce loss of power that occurs in dissipative snubber. Principal criteria in design: low cost, simplicity, and reliability.
Decreasing the commutation failure frequency in HVDC transmission systems
DEFF Research Database (Denmark)
Hansen (retired June, 2000), Arne; Havemann (retired June, 2000), Henrik
2000-01-01
In this paper we show how a fairly large proportion of those commutation failures that are due to single-phased short circuits to earth can be avoided. In a control circuit based on a digital signal processor (DSP) it is possible, with instantaneous results, to switch from a normal control strategy...
Directory of Open Access Journals (Sweden)
Zuhua Zhang
2016-08-01
Full Text Available The pore characteristics of GFCs manufactured in the laboratory with 0-16% foam additions were examined using image analysis (IA and vacuum water saturation techniques. The pore size distribution, pore shape and porosity were obtained. The IA method provides a suitable approach to obtain the information of large pores, which are more important in affecting the compressive strength of GFC. By examining the applicability of the existing models of predicting compressive strength of foam concrete, a modified Ryshkevitch’s model is proposed for GFC, in which only the porosity that is contributed by the pores over a critical diameter (>100 μm is considered. This critical void model is shown to have very satisfying prediction capability in the studied range of porosity. A compression-modulus model for Portland cement concrete is recommended for predicting the compression modulus elasticity of GFC. This study confirms that GFC have similar pore structures and mechanical behavior as those Portland cement foam concrete and can be used alternatively in the industry for the construction and insulation purposes.
Zhang, Zuhua; Wang, Hao
2016-08-01
The pore characteristics of GFCs manufactured in the laboratory with 0-16% foam additions were examined using image analysis (IA) and vacuum water saturation techniques. The pore size distribution, pore shape and porosity were obtained. The IA method provides a suitable approach to obtain the information of large pores, which are more important in affecting the compressive strength of GFC. By examining the applicability of the existing models of predicting compressive strength of foam concrete, a modified Ryshkevitch’s model is proposed for GFC, in which only the porosity that is contributed by the pores over a critical diameter (>100 μm) is considered. This “critical void model” is shown to have very satisfying prediction capability in the studied range of porosity. A compression-modulus model for Portland cement concrete is recommended for predicting the compression modulus elasticity of GFC. This study confirms that GFC have similar pore structures and mechanical behavior as those Portland cement foam concrete and can be used alternatively in the industry for the construction and insulation purposes.
Analysis of Subway Interior Noise at Peak Commuter Time.
Lee, Donguk; Kim, Gibbeum; Han, Woojae
2017-07-01
Although mass transit systems are convenient and efficient for urban people, little attention has been paid to the potential hearing hazard from their noise. The purpose of the current study was to measure and analyze levels of subway interior noise at peak commuter times and to provide information about commuters' daily dose of noise exposure. To measure the subway interior noise, nine subway lines inside Seoul (i.e., lines 1-9) and six lines surrounding the capital city area (i.e., Central, Bundang, Sinbundang, Incheon, Gyeongui, and Gyeongchun) were chosen. The noise was measured and recorded by a sound level meter for two-hour periods in the morning and evening. 1) In the LZeq analysis, the average noise level of all 15 lines was 72.78 dB; the maximum and minimum noise levels were 78.34 and 62.46 dB, respectively. The average noise level of the nine lines inside Seoul was 73.45 dB, which was 1.68-dB louder than that of the six lines surrounding the capital city area. 2) Based on the LZeq analysis of 33 measured frequencies, 12.5 Hz was the highest frequency and 20,000 Hz was the lowest. 3) There was no remarkable difference in the level of subway interior noise between morning and evening peak commuter times. We concluded that the level of subway interior noise was not loud enough for commuters to incur noise-induced hearing loss. Regardless, environmental noise control efforts in the subway system might be needed for commuters who take a subway every day.
Active commuting to school: How far is too far?
Directory of Open Access Journals (Sweden)
Moyna Niall M
2008-01-01
Full Text Available Abstract Background Walking and cycling to school provide a convenient opportunity to incorporate physical activity into an adolescent's daily routine. School proximity to residential homes has been identified as an important determinant of active commuting among children. The purpose of this study is to identify if distance is a barrier to active commuting among adolescents, and if there is a criterion distance above which adolescents choose not to walk or cycle. Methods Data was collected in 2003–05 from a cross-sectional cohort of 15–17 yr old adolescents in 61 post primary schools in Ireland. Participants self-reported distance, mode of transport to school and barriers to active commuting. Trained researchers took physical measurements of height and weight. The relation between mode of transport, gender and population density was examined. Distance was entered into a bivariate logistic regression model to predict mode choice, controlling for gender, population density socio-economic status and school clusters. Results Of the 4013 adolescents who participated (48.1% female, mean age 16.02 ± 0.661, one third walked or cycled to school. A higher proportion of males than females commuted actively (41.0 vs. 33.8%, χ2 (1 = 22.21, p 2 (df = 3 = 839.64, p 2 (df = 1 = 2591.86, p Conclusion Distance is an important perceived barrier to active commuting and a predictor of mode choice among adolescents. Distances within 2.5 miles are achievable for adolescent walkers and cyclists. Alternative strategies for increasing physical activity are required for individuals living outside of this criterion.
Longitudinal associations of active commuting with wellbeing and sickness absence.
Mytton, Oliver Tristan; Panter, Jenna; Ogilvie, David
2016-03-01
Our aim was to explore longitudinal associations of active commuting (cycling to work and walking to work) with physical wellbeing (PCS-8), mental wellbeing (MCS-8) and sickness absence. We used data from the Commuting and Health in Cambridge study (2009 to 2012; n=801) to test associations between: a) maintenance of cycling (or walking) to work over a one year period and indices of wellbeing at the end of that one year period; and b) associations between change in cycling (or walking) to work and change in indices of wellbeing. Linear regression was used for testing associations with PCS-8 and MCS-8, and negative binomial regression for sickness absence. After adjusting for sociodemographic variables, physical activity and physical limitation, those who maintained cycle commuting reported lower sickness absence (0.46, 95% CI: 0.14-0.80; equivalent to one less day per year) and higher MCS-8 scores (1.50, 0.10-2.10) than those who did not cycle to work. The association for sickness absence persisted after adjustment for baseline sickness absence. No significant associations were observed for PCS-8. Associations between change in cycle commuting and change in indices of wellbeing were not significant. No significant associations were observed for walking. This work provides some evidence of the value of cycle commuting in improving or maintaining the health and wellbeing of adults of working age. This may be important in engaging employers in the promotion of active travel and communicating the benefits of active travel to employees. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.
Directory of Open Access Journals (Sweden)
Luiz Claudio Pardini
2002-10-01
Full Text Available Carbon fibres and glass fibres are reinforcements for advanced composites and the fiber strength is the most influential factor on the strength of the composites. They are essentially brittle and fail with very little reduction in cross section. Composites made with these fibres are characterized by a high strength/density ratio and their properties are intrisically related to their microstructure, i.e., amount and orientation of the fibres, surface treatment, among other factors. Processing parameters have an important role in the fibre mechanical behaviour (strength and modulus. Cracks, voids and impurities in the case of glass fibres and fibrillar misalignments in the case of carbon fibres are created during processing. Such inhomogeneities give rise to an appreciable scatter in properties. The most used statistical tool that deals with this characteristic variability in properties is the Weibull distribution. The present work investigates the influence of the testing gage length on the strength, Young's modulus and Weibull modulus of carbon fibres and glass fibres. The Young's modulus is calculated by two methods: (i ASTM D 3379M, and (ii interaction between testing equipment/specimen The first method resulted in a Young modulus of 183 GPa for carbon fibre, and 76 GPa for glass fibre. The second method gave a Young modulus of 250 GPa for carbon fibre and 50 GPa for glass fibre. These differences revelead differences on how the interaction specimen/testing machine can interfere in the Young modulus calculations. Weibull modulus can be a tool to evaluate the fibre's homogeneity in terms of properties and it is a good quality control parameter during processing. In the range of specimen gage length tested the Weibull modulus for carbon fibre is ~ 3.30 and for glass fibres is ~ 5.65, which indicates that for the batch of fibres tested, the glass fibre is more uniform in properties.
Elasticity modulus and damping ratio of macaw palm rachillas
National Research Council Canada - National Science Library
Villar, Flora Maria de Melo; Pinto, Francisco de Assis de Carvalho; Santos, Fábio Lúcio; Grossi, José Antônio Saraiva; Velloso, Nara Silveira
2017-01-01
.... Thus, this study seeks to determine the modulus of elasticity and the damping ratio of four different plant accessions obtained from the Active Germplasm Bank of the Universidade Federal de Viçosa (UFV...
Frequency-dependent complex modulus of the uterus: preliminary results
Energy Technology Data Exchange (ETDEWEB)
Kiss, Miklos Z [Department of Medical Physics, University of Wisconsin, Madison, WI 53706 (United States); Hobson, Maritza A [Department of Medical Physics, University of Wisconsin, Madison, WI 53706 (United States); Varghese, Tomy [Department of Medical Physics, University of Wisconsin, Madison, WI 53706 (United States); Harter, Josephine [Department of Surgical Pathology, University of Wisconsin, Madison, WI 53706 (United States); Kliewer, Mark A [Department of Radiology, University of Wisconsin, Madison, WI 53706 (United States); Hartenbach, Ellen M [Department of Obstetrics and Gynecology, University of Wisconsin, Madison, WI 53706 (United States); Zagzebski, James A [Department of Medical Physics, University of Wisconsin, Madison, WI 53706 (United States)
2006-08-07
The frequency-dependent complex moduli of human uterine tissue have been characterized. Quantification of the modulus is required for developing uterine ultrasound elastography as a viable imaging modality for diagnosing and monitoring causes for abnormal uterine bleeding and enlargement, as well assessing the integrity of uterine and cervical tissue. The complex modulus was measured in samples from hysterectomies of 24 patients ranging in age from 31 to 79 years. Measurements were done under small compressions of either 1 or 2%, at low pre-compression values (either 1 or 2%), and over a frequency range of 0.1-100 Hz. Modulus values of cervical tissue monotonically increased from approximately 30-90 kPa over the frequency range. Normal uterine tissue possessed modulus values over the same range, while leiomyomas, or uterine fibroids, exhibited values ranging from approximately 60-220 kPa.
Nonperturbative QED vacuum birefringence
Denisov, V. I.; Dolgaya, E. E.; Sokolov, V. A.
2017-05-01
In this paper we represent nonperturbative calculation for one-loop Quantum Electrodynamics (QED) vacuum birefringence in presence of strong magnetic field. The dispersion relations for electromagnetic wave propagating in strong magnetic field point to retention of vacuum birefringence even in case when the field strength greatly exceeds Sauter-Schwinger limit. This gives a possibility to extend some predictions of perturbative QED such as electromagnetic waves delay in pulsars neighbourhood or wave polarization state changing (tested in PVLAS) to arbitrary magnetic field values. Such expansion is especially important in astrophysics because magnetic fields of some pulsars and magnetars greatly exceed quantum magnetic field limit, so the estimates of perturbative QED effects in this case require clarification.
Energy Technology Data Exchange (ETDEWEB)
Hamer, J.A.; Burg, C.J. Van Der; Kanbier, D.; Heijden, P. Van Der.
1990-09-18
This invention relates to a vacuum distillation device comprising a vacuum distillation column, a furnace provided with a heat exchange tube, and a connecting conduit between the column and the heat exchange tube. Such a device is used to fractionate a hydrocarbon-containing feed sometimes referred to as long residue. An object of this invention is to provide a vacuum distillation device which allows vaporization of a major part of the feed upstream of the column inlet. To this end, the device according to the invention comprises a vacuum distillation device as described above, in which the inner diameter of the heat exchange tube increases along its length to between 2.4 and 3 times the inner diameter of the tube inlet, and in which the inner diameter of the connecting conduit gradually increases along its length to between 2.5 and 5.4 times the inner diameter of the tube outlet. During normal operation of the device of the invention, only less than 50 wt % of the feed is vaporized in the heat exchange tube in the furnace, and more feed is vaporized in the connecting conduit, so that at the outlet end of the conduit the feed comprises about 0.9 kg vapor per kg of feed. The invention provides improved heat transfer in the heat exchange tubes such that fouling is reduced, consequently more heat can be applied per unit of time in the heat exchange tube. This allows either heating of the feed to a higher temperature or increasing the throughput for the same temperature.
The equationally-defined commutator a study in equational logic and algebra
Czelakowski, Janusz
2015-01-01
This monograph introduces and explores the notions of a commutator equation and the equationally-defined commutator from the perspective of abstract algebraic logic. An account of the commutator operation associated with equational deductive systems is presented, with an emphasis placed on logical aspects of the commutator for equational systems determined by quasivarieties of algebras. The author discusses the general properties of the equationally-defined commutator, various centralization relations for relative congruences, the additivity and correspondence properties of the equationally-defined commutator, and its behavior in finitely generated quasivarieties. Presenting new and original research not yet considered in the mathematical literature, The Equationally-Defined Commutator will be of interest to professional algebraists and logicians, as well as graduate students and other researchers interested in problems of modern algebraic logic.
PARAFFIN SEPARATION VACUUM DISTILLATION
Directory of Open Access Journals (Sweden)
Zaid A. Abdulrahman
2013-05-01
Full Text Available Simulated column performance curves were constructed for existing paraffin separation vacuum distillation column in LAB plant (Arab Detergent Company/Baiji-Iraq. The variables considered in this study are the thermodynamic model option, top vacuum pressure, top and bottom temperatures, feed temperature, feed composition & reflux ratio. Also simulated columns profiles for the temperature, vapor & liquid flow rates composition were constructed. Four different thermodynamic model options (SRK, TSRK, PR, and ESSO were used, affecting the results within 1-25% variation for the most cases.The simulated results show that about 2% to 8 % of paraffin (C10, C11, C12, & C13 present at the bottom stream which may cause a problem in the LAB plant. The major variations were noticed for the top temperature & the paraffin weight fractions at bottom section with top vacuum pressure. The bottom temperature above 240 oC is not recommended because the total bottom flow rate decreases sharply, where as the weight fraction of paraffins decrease slightly. The study gives evidence about a successful simulation with CHEMCAD
Resilient Modulus Characterization of Compacted Cohesive Subgrade Soil
Directory of Open Access Journals (Sweden)
Wojciech Sas
2017-04-01
Full Text Available Soil investigations concerning cyclic loading focus on the evaluation, in particular, of design parameters, such as elastic modulus, Poisson’s ratio, or resilient modulus. Structures subjected to repeated loading are vulnerable to high deformations, especially when subgrade soils are composed of cohesive, fully-saturated soils. Such subgrade soils in the eastern part of Europe have a glacial genesis and are a mix of sand, silt, and clay fractions. The characteristic of, e.g., Young modulus variation and resilient modulus from repeated loading tests, is presented. Based on performed resonant column and cyclic triaxial tests, an analytical model is proposed. The model takes into consideration actual values of effective stress p′, as well as loading characteristics and the position of the effective stress path. This approach results in better characterization of pavement or industrial foundation systems based on the subgrade soil in undrained conditions. The recoverable strains characterized by the resilient modulus Mr value in the first cycle of loading was between 44 MPa and 59 MPa for confining pressure σ’3 equal to 45 kPa, and between 48 MPa and 78 MPa for σ’3 equal to 90 kPa. During cyclic loading, cohesive soil, at first, degrades. When pore pressure reaches equilibrium, the resilient modulus value starts to increase. The above-described phenomena indicate that, after the plastic deformation caused by excessive load and excess pore water pressure dissipation, the soil becomes resilient.
Yang, Lin; Panter, Jenna; Griffin, Simon J.; Ogilvie, David
2012-01-01
Objective To quantify the association between time spent in active commuting and in moderate to vigorous physical activity (MVPA) in a sample of working adults living in both urban and rural locations. Methods In 2009, participants in the Commuting and Health in Cambridge study were sent questionnaires enquiring about sociodemographic characteristics and weekly time spent in active commuting. They were also invited to wear an accelerometer for seven days. Accelerometer data were used to compute the time spent in MVPA. Multiple regression models were used to examine the association between time spent in active commuting and MVPA. Results 475 participants (70% female) provided valid data. On average, participants recorded 55 (SD: 23.02) minutes of MVPA per day. For women, reporting 150 or more minutes of active commuting per week was associated with an estimated 8.50 (95% CI: 1.75 to 51.26, p = 0.01) additional minutes of daily MVPA compared to those who reported no time in active commuting. No overall associations were found in men. Conclusions Promoting active commuting might be an important way of increasing levels of physical activity, particularly in women. Further research should assess whether increases in time spent in active commuting are associated with increases in physical activity. PMID:22964003
Route Choice Model Based on Game Theory for Commuters
Directory of Open Access Journals (Sweden)
Licai Yang
2016-06-01
Full Text Available The traffic behaviours of commuters may cause traffic congestion during peak hours. Advanced Traffic Information System can provide dynamic information to travellers. Due to the lack of timeliness and comprehensiveness, the provided information cannot satisfy the travellers’ needs. Since the assumptions of traditional route choice model based on Expected Utility Theory conflict with the actual situation, a route choice model based on Game Theory is proposed to provide reliable route choice to commuters in actual situation in this paper. The proposed model treats the alternative routes as game players and utilizes the precision of predicted information and familiarity of traffic condition to build a game. The optimal route can be generated considering Nash Equilibrium by solving the route choice game. Simulations and experimental analysis show that the proposed model can describe the commuters’ routine route choice decisionexactly and the provided route is reliable.
Modelling the relation between income and commuting distance
DEFF Research Database (Denmark)
Carra, Giulia; Mulalic, Ismir; Fosgerau, Mogens
2016-01-01
We discuss the distribution of commuting distances and its relation to income. Using data from Denmark, the UK and the USA, we show that the commuting distance is (i) broadly distributed with a slow decaying tail that can be fitted by a power law with exponent γ ≈ 3 and (ii) an average growing...... slowly as a power law with an exponent less than one that depends on the country considered. The classical theory for job search is based on the idea that workers evaluate the wage of potential jobs as they arrive sequentially through time, and extending this model with space, we obtain predictions...... that are strongly contradicted by our empirical findings. We propose an alternative model that is based on the idea that workers evaluate potential jobs based on a quality aspect and that workers search for jobs sequentially across space. We also assume that the density of potential jobs depends on the skills...
Structure of weakly periodic rings with potent extended commutators
Adil Yaqub
2001-01-01
A well-known theorem of Jacobson (1964, page 217) asserts that a ring R with the property that, for each x in R, there exists an integer n(x)>1 such that xn(x)=x is necessarily commutative. This theorem is generalized to the case of a weakly periodic ring R with a sufficient number of potent extended commutators. A ring R is called weakly periodic if every x in R can be written in the form x=a+b, where a is nilpotent and b is potent in the sense that bn(b)=b for some integer n(b)>1. It is...
Nakano, Harumi; Inoue, Sakae
2010-01-01
We measured how much physical exercise of moderate-to-high intensity was performed daily during commuting times by office workers who reside in the Greater Tokyo Area and use a train for commuting. The physical activity was measured by a portable accelerometer, Omron HJA-350 IT, which records METs (Metabolic Equivalents) every minute. The data were downloaded to a personal computer for calculation of the exercise quantity in specified time intervals. Exercise (Ex) was defined as (METs> or =3) x hours. Male commuters using the train (n=74) were found to spend 70 +/- 30 and 103 +/- 47 minutes for morning and evening commuting, respectively. They expended 3.4 +/- 1.7 Ex in the commuting of both morning and evening. This exercise quantity amounts to 64% of the whole day Ex, which was 2.9 times the whole day Ex of car commuters (n=78). The daily walking activity of the train commuters, 9,305 +/- 2,651 steps, was 2.7 times that of the car commuters (3,490 +/- 1,406 steps). The mean total Ex expended by the train commuters over 5 weekdays was calculated to be 26.5 Ex, which exceeds the weekly 23 Ex recommended by Guideline on Physical Exercise for Good Health, 2006, Japanese Ministry of Health, Labour, and Welfare. Train commuting by office workers residing in the Greater Tokyo Area seems to contribute to their physical health.
McNab, A.
2017-10-01
This paper describes GridPP’s Vacuum Platform for managing virtual machines (VMs), which has been used to run production workloads for WLCG and other HEP experiments. The platform provides a uniform interface between VMs and the sites they run at, whether the site is organised as an Infrastructure-as-a-Service cloud system such as OpenStack, or an Infrastructure-as-a-Client system such as Vac. The paper describes our experience in using this platform, in developing and operating VM lifecycle managers Vac and Vcycle, and in interacting with VMs provided by LHCb, ATLAS, ALICE, CMS, and the GridPP DIRAC service to run production workloads.
Vacuum ultraviolet spectroscopy I
Samson, James A; Lucatorto, Thomas
1998-01-01
This volume is for practitioners, experimentalists, and graduate students in applied physics, particularly in the fields of atomic and molecular physics, who work with vacuum ultraviolet applications and are in need of choosing the best type of modern instrumentation. It provides first-hand knowledge of the state-of-the-art equipment sources and gives technical information on how to use it, along with a broad reference bibliography.Key Features* Aimed at experimentalists who are in need of choosing the best type of modern instrumentation in this applied field* Contains a detailed chapter on la
Active commuting of the inhabitants of Liberec city in low and high walkability areas
Directory of Open Access Journals (Sweden)
Lukáš Rubín
2015-12-01
Full Text Available Background: Active commuting in terms of everyday transport to school or work can have a significant effect on physical activity. Active commuting can be influenced by the environment, and examples from abroad show that current environmental changes tend mostly to promote passive forms of commuting. A similar situation of decreasing active commuting might be expected in the Czech Republic. However, little information has been published to date about the issue of active commuting among the inhabitants of our country. Objective: The main objective of the present study is to describe the active commuting patterns of the inhabitants of Liberec city in low and high walkability areas. Methods: A total of 23,621 economically active inhabitants or students of Liberec city aged 6-87 years (34.77 ± 14.39 participated in the study. The data about commuting were retrieved from the national Population and Housing Census of 2011. Geographic information systems were used to objectively analyze the built environment and to calculate the walkability index. Results: Active commuting to/from school or work is used by 17.41% of inhabitants. Active commuting is dominated by walking (16.60% as opposed to cycling (0.81%. Inhabitants who lived in high walkability areas were more likely to actively commute than those living in low walkability areas (OR = 1.54; 95% CI [1.41, 1.68]. Conclusions: This study confirmed the findings of international studies about the effect of the built environment on active commuting among Liberec inhabitants. Active commuters are often those living near or in the city center, which is characterized by high walkability. In Liberec city, walking as a means of active commuting significantly prevails over cycling. One of the reasons might be the diverse topography of the city and the insufficiently developed cycling network.
Longitudinal associations between built environment characteristics and changes in active commuting
Directory of Open Access Journals (Sweden)
Lin Yang
2017-05-01
Full Text Available Abstract Background Few studies have assessed the predictors of changes in commuting. This study investigated the associations between physical environmental characteristics and changes in active commuting. Methods Adults from the population-based European Prospective Investigation into Cancer (EPIC-Norfolk cohort self-reported commuting patterns in 2000 and 2007. Active commuters were defined as those who reported ‘always’ or ‘usually’ walking or cycling to work. Environmental attributes around the home and route were assessed using Geographical Information Systems. Associations between potential environmental predictors and uptake and maintenance of active commuting were modelled using logistic regression, adjusting for age, sex and BMI. Results Of the 2757 participants (62% female, median baseline age: 52, IQR: 50–56 years, most were passive commuters at baseline (76%, n = 2099 and did not change their usual commute mode over 7 years (82%, n = 2277. In multivariable regression models, participants living further from work were less likely to take up active commuting and those living in neighbourhoods with more streetlights were more likely to take up active commuting (both p < 0.05. Findings for maintenance were similar: participants living further from work (over 10 km, OR: 0.06; 95% CI: 0.25 to 0.13 and had a main or secondary road on route were more likely to maintain their active commuting (OR: 0.52; 95% CI: 0.28 to 0.98. Those living in neighbourhoods with greater density of employment locations were less likely to maintain their active commuting. Conclusions Co-locating residential and employment centres as well as redesigning urban areas to improve safety for pedestrians and cyclists may encourage active commuting. Future evaluative studies should seek to assess the effects of redesigning the built environment on active commuting and physical activity.
Djurhuus, Sune; Hansen, Henning Sten; Aadahl, Mette; Glümer, Charlotte
2014-01-01
Active commuters have lower risk of chronic disease. Understanding which of the, to some extent, modifiable characteristics of public transportation that facilitate its use is thus important in a public health perspective. The aim of the study was to examine the association between individual public transportation accessibility and self-reported active commuting, and whether the associations varied with commute distance, age, and gender. Twenty-eight thousand nine hundred twenty-eight commuters in The Capital Region of Denmark reported self-reported time spent either walking or cycling to work or study each day and the distance to work or study. Data were obtained from the Danish National Health Survey collected in February to April 2010. Individual accessibility by public transportation was calculated using a multi-modal network in a GIS. Multilevel logistic regression was used to analyze the association between accessibility, expressed as access area, and being an active commuter. Public transport accessibility area based on all stops within walking and cycling distance was positively associated with being an active commuter. Distance to work, age, and gender modified the associations. Residing within 10 km commute distance and in areas of high accessibility was associated with being an active commuter and meeting the recommendations of physical activity. For the respondents above 29 years, individual public transportation accessibility was positively associated with being an active commuter. Women having high accessibility had significantly higher odds of being an active commuter compared to having a low accessibility. For men, the associations were insignificant. This study extends the knowledge about the driving forces of using public transportation for commuting by examining the individual public transportation accessibility. Findings suggest that transportation accessibility supports active commuting and planning of improved public transit accessibility
Energy Technology Data Exchange (ETDEWEB)
Mapes, M.; Smart, L.; Weiss, D.; Steszyn, A.; Todd, R.
2010-01-01
The ERL Vacuum systems are depicted in a figure. ERL has eight vacuum volumes with various sets of requirements. A summary of vacuum related requirements is provided in a table. Five of the eight volumes comprise the electron beamline. They are the 5-cell Superconducting RF Cavity, Superconducting e-gun, injection, loop and beam dump. Two vacuum regions are the individual cryostats insulating the 5-cell Superconducting RF Cavity and the Superconducting e-gun structures. The last ERL vacuum volume not shown in the schematic is the laser transport line. The beamline vacuum regions are separated by electropneumatic gate valves. The beam dump is common with loop beamline but is considered a separate volume due to geometry and requirements. Vacuum in the 5-cell SRF cavity is maintained in the {approx}10{sup -9} torr range at room temperature by two 20 l/s ion pumps and in the e-gun SRF cavity by one 60 l/s ion pump. Vacuum in the SRF cavities operated at 2{sup o}K is reduced to low 10{sup -11} torr via cryopumping of the cavity walls. The cathode of the e-gun must be protected from poisoning, which can occur if vacuum adjacent to the e-gun in the injection line exceeds 10-11 torr range in the injection warm beamline near the e-gun exit. The vacuum requirements for beam operation in the loop and beam dump are 10-9 torr range. The beamlines are evacuated from atmospheric pressure to high vacuum level with a particulate free, oil free turbomolecular pumping cart. 25 l/s shielded ion pumps distributed throughout the beamlines maintain the vacuum requirement. Due to the more demanding vacuum requirement of the injection beamline proximate to the e-gun, a vacuum bakeout of the injection beamline is required. In addition, two 200 l/s diode ion pumps and supplemental pumping provided by titanium sublimation pumps are installed in the injection line just beyond the exit of the e-gun. Due to expected gas load a similar pumping arrangement is planned for the beam dump. The
Shear modulus reconstruction by ultrasonically measured strain ratio.
Sumi, Chikayoshi; Matsuzawa, Hidenori
2007-12-01
In addition to a description of our three previously developed one-dimensional (1D) methods from the viewpoint of shear modulus reconstruction using the strain ratio, two new methods for stabilizing the 1D methods are described, together with their limitations. As confirmed using human in vivo breast tissues, method 1 for evaluating the strain ratio itself is useful when the measurement accuracy of the strain distribution is high. However, because tissues having high shear moduli, such as scirrhous carcinoma, often form singular points/regions, both methods 2 and 3 using the strain ratio (initial estimate) and a regularization method are effective for realizing a unique, stable, useful shear modulus reconstruction. Because method 3 carries out implicit integration only at singular points/regions, whereas method 2 carries out implicit integration throughout the region of interest (ROI), the smaller number of singular points enables more rapid shear modulus reconstruction by method 3 than by method 2. Like method 1, method 3 is also useful when the measurement accuracy of the strain distribution is high. However, when evaluating strain distribution in an ROI with a high spatial resolution to obtain a shear modulus reconstruction having a high spatial resolution, shear modulus reconstructions obtained by methods 1, 2, and 3 often become laterally unstable due to the instability and low accuracy of the strains in the reference regions (reference strains), i.e., regularization in methods 2 and 3 cannot reduce the instability in the initial estimate. To cope with this instability, (i) the reconstruction obtained by calculating the strain ratio should be low-pass filtered; for breast tissues, in particular, the reconstruction of the inverse shear modulus should be low-pass filtered, not the reconstruction of the shear modulus. (ii) Otherwise, when using homogeneous regions as a reference, such as a block of reference material, fatty tissue, or parenchyma, evaluation of
Fully controlled 5-phase, 10-pulse, line commutated rectifier
Masoud, Mahmoud I.
2015-01-01
The development and production of multiphase machines either generators or motors, specially five-phase, offers improved performance compared to three-phase counterpart. Five phase generators could generate power in applications such as, but not limited to, wind power generation, electric vehicles, aerospace, and oil and gas. The five-phase generator output requires converter system such as ac–dc converters. In this paper, a fully controlled 10-pulse line commutated rectifier, suitable to be ...
First Commuter Air Carrier Safety Symposium, January 16 - 17, 1980.
1980-01-01
airlines. 18 I suppose an underlying question which provides the frame - work or the starting point for this symposium is: How safe are commuters? And...the volatility factor in commercial aviation and the cautions which must be exercised in making statistical judgments based on one-year time frames . In...that I am stil not satis- fied. There are too many delays. There is too much lethargy. There is too much time lag between the identification of safety
A study on mobility improvement for intellectually disabled student commuters
Directory of Open Access Journals (Sweden)
Fumihiko Nakamura
2017-07-01
Overall, our findings suggested that to actually implement mobility support in school commuting environments in a way that will improve the mobility of intellectually disabled people requires not only the cooperation of schools, but also contributions from transport operators, road administrators, and traffic administrators. Because the contributions of these entities are essential, awareness-raising activities and a system for promoting common understanding among them are vital.
Particle exposure and inhaled dose during commuting in Singapore
Tan, Sok Huang; Roth, Matthias; Velasco, Erik
2017-12-01
Exposure concentration and inhaled dose of particles during door-to-door trips walking and using motorized transport modes (subway, bus, taxi) are evaluated along a selected route in a commercial district of Singapore. Concentrations of particles smaller than 2.5 μm in size (PM2.5), black carbon, particle-bound polycyclic aromatic hydrocarbons, number of particles, active surface area and carbon monoxide have been measured in-situ using portable instruments. Simultaneous measurements were conducted at a nearby park to capture the background concentrations. The heart rate of the participants was monitored during the measurements as a proxy of the inhalation rate used to calculate the inhaled dose of particles. All measured metrics were highest and well above background levels during walking. No significant difference was observed in the exposure concentration of PM2.5 for the three motorized transport modes, unlike for the metrics associated with ultrafine particles (UFP). The concentration of these freshly emitted particles was significantly lower on subway trips. The absence of combustion sources, use of air conditioning and screen doors at station platforms are effective measures to protect passengers' health. For other transport modes, sections of trips close to accelerating and idling vehicles, such as bus stops, traffic junctions and taxi stands, represent hotspots of particles. Reducing the waiting time at such locations will lower pollutants exposure and inhaled dose during a commute. After taking into account the effect of inhalation and travel duration when calculating dose, the health benefit of commuting by subway for this particular district of Singapore became even more evident. For example, pedestrians breathe in 2.6 and 3.2 times more PM2.5 and UFP, respectively than subway commuters. Public buses were the second best alternative. Walking emerged as the worst commuting mode in terms of particle exposure and inhaled dose.
Limit algebras of differential forms in non-commutative geometry
Indian Academy of Sciences (India)
The GNS-representation of ∞A defined by a d-dimensional non-commutative volume integral on a d+-summable K-cycle on A is realized as the representation induced by the left action of A on ∗A. This supplements the representation A on the space of forms discussed by Connes (Ch. VI.1, Prop. 5, p. 550 of [C]).
A community intervention to prevent traffic accidents among bicycle commuters.
Bacchieri, Giancarlo; Barros, Aluísio J D; Santos, Janaína V dos; Gonçalves, Helen; Gigante, Denise P
2010-10-01
To evaluate an educational intervention designed to prevent traffic accidents among workers that use the bicycle for commuting. A longitudinal intervention study with a stepped wedge implementation was carried out between January 2006 and May 2007. Five neighborhoods with distinct geographic characteristics were selected in the city of Pelotas, Brazil, and 42 census tracts were randomly selected from these neighborhoods. All households were screened for male bicycle commuters, resulting in a sample of 1,133 individuals. The outcomes analyzed were "traffic accidents" and "near accidents". The cyclists were interviewed monthly by phone to record traffic accidents and "near accidents". Every 15 days, from the second month of study, a group of about 60 cyclists was invited to attend the intervention meeting that included an educational component (a talk and a video presentation), distribution of a safety kit (reflective belt & sash, reflective tape and an educational booklet) and a bicycle breaks check-up (maintenance performed if necessary). Poisson regression adjusted for time effect was used to assess the intervention effect. Nearly 45% of the cyclists did not attend the intervention. During the study period, 9% of the study individuals reported a traffic accident and 88% reported a "near accident". In total there were 106 accidents and 1,091 near accidents. There was no effect observed from the intervention on either of the outcomes. The intervention tested was not capable of reducing traffic accidents among bicycle commuters. Lack of interest in safety by commuters and external factors, such as road design and motorist behavior, may have together influenced this result.
AC system stabilization via phase shift transformer with thyristor commutation
Energy Technology Data Exchange (ETDEWEB)
Oliveira, Jose Carlos de; Guimaraes, Geraldo Caixeta; Moraes, Adelio Jose [Uberlandia Univ., MG (Brazil); Abreu, Jose Policarpo G. de [Escola Federal de Engenharia de Itajuba, MG (Brazil); Oliveira, Edimar Jose de [Juiz de Fora Univ., MG (Brazil)
1994-12-31
This article aims to present initially the constructive and operative forms of a phase-shift autotransformer which provides both magnitude and phase angle change through thyristor commutation, including a technic to reduce the number of thyristors. Following, it is proposed a control system to make such equipment an efficient AC system stabilizing tool. It is presented some simulation results to show the operation of this transformer in an electrical system. (author) 3 refs., 11 figs., 3 tabs.
A norm inequality for pairs of commuting positive semidefinite matrices
Audenaert, Koenraad M. R.
2014-01-01
For $k=1,\\ldots,K$, let $A_k$ and $B_k$ be positive semidefinite matrices such that, for each $k$, $A_k$ commutes with $B_k$. We show that, for any unitarily invariant norm, \\[ |||\\sum_{k=1}^K A_kB_k||| \\le ||| (\\sum_{k=1}^K A_k)\\;(\\sum_{k=1}^K B_k)|||. \\
Commutability of Cytomegalovirus WHO International Standard in Different Matrices.
Jones, Sara; Webb, Erika M; Barry, Catherine P; Choi, Won S; Abravaya, Klara B; Schneider, George J; Ho, Shiaolan Y
2016-06-01
Commutability of quantitative standards allows patient results to be compared across molecular diagnostic methods and laboratories. This is critical to establishing quantitative thresholds for use in clinical decision-making. A matrix effect associated with the 1st cytomegalovirus (CMV) WHO international standard (IS) was identified using the Abbott RealTime CMV assay. A commutability study was performed to compare the CMV WHO IS and patient specimens diluted in plasma and whole blood. Patient specimens showed similar CMV DNA quantitation values regardless of the diluent or extraction procedure used. The CMV WHO IS, on the other hand, exhibited a matrix effect. The CMV concentration reported for the WHO IS diluted in plasma was within the 95% prediction interval established with patient samples. In contrast, the reported DNA concentration of the CMV WHO IS diluted in whole blood was reduced approximately 0.4 log copies/ml, and values fell outside the 95% prediction interval. Calibrating the assay by using the CMV WHO IS diluted in whole blood would introduce a bias for CMV whole-blood quantitation; samples would be reported as having higher measured concentrations, by approximately 0.4 log IU/ml. Based on the commutability study with patient samples, the RealTime CMV assay was standardized based on the CMV WHO IS diluted in plasma. A revision of the instructions for use of the CMV WHO IS should be considered to alert users of the potential impact from the diluent matrix. The identification of a matrix effect with the CMV WHO IS underscores the importance of assessing commutability of the IS in order to achieve consistent results across methods. Copyright © 2016 Jones et al.
Research on Fatigue Strain and Fatigue Modulus of Concrete
Directory of Open Access Journals (Sweden)
Fangping Liu
2017-01-01
Full Text Available Concrete fatigue strain and fatigue modulus evolution play a vital role in the evaluation of the material properties. In this paper, by analyzing the advantages and disadvantages of existing concrete strain analysis methods, the level-S nonlinear fatigue strain model was proposed. The parameters’ physical meaning, the ranges, and the impact on the shape of the curve were all discussed. Then, the evolution model of fatigue modulus was established based on the fatigue strain evolution model and the hypothesis of fatigue modulus inversely related fatigue strain amplitude. The results indicate that the level-S model covered all types of fatigue strain evolution. It is very suitable for the description of strain evolution of concrete for its strong adaptability and high accuracy. It was found that the fitting curves coincided with the experimental curves very well, and the correlation coefficients were all above 0.98. The evolution curves of fatigue strain modulus both have three stages, namely, variation phase, linear change stage, and convergence stage. The difference is that the fatigue strain evolution curve is from the lower left corner to the upper right corner, but the fatigue modulus evolution curve is from the upper left corner to the right lower corner.
Unveiling descriptors for predicting the bulk modulus of amorphous carbon
Takahashi, Keisuke; Tanaka, Yuzuru
2017-02-01
Descriptors for the bulk modulus of amorphous carbon are investigated through the implementation of data mining where data sets are prepared using first-principles calculations. Data mining reveals that the number of bonds in each C atom and the density of amorphous carbon are found to be descriptors representing the bulk modulus. Support vector regression (SVR) within machine learning is implemented and descriptors are trained where trained SVR is able to predict the bulk modulus of amorphous carbon. An inverse problem, starting from the bulk modulus towards structural information of amorphous carbon, is performed and structural information of amorphous carbon is successfully predicted from the desired bulk modulus. Thus, treating several physics factors in multidimensional space allows for the prediction of physical phenomena. In addition, the reported approach proposes that "big data" can be generated from a small data set using machine learning if descriptors are well defined. This would greatly change how amorphous carbon would be treated and help accelerate further development of amorphous carbon materials.
Take part in the Commute-Another-Way Challenge!
CERN Bulletin
2015-01-01
Ring the changes on Thursday, 4 June by commuting another way! CERN has signed up for the 5th “challenge mobilité Rhône-Alpes”, the aim of which is to encourage people to use modes of transport other than their car to get to work. Are you up for the challenge? Join in the challenge! Sign up using the dedicated CERN form. "Commute another way!" is an initiative launched by the Rhône-Alpes regional authorities and the French environment agency ADEME (l’Agence de l’environnement et de la maîtrise de l’énergie française) to promote alternative ways of travelling to work than the car (excluding carpooling), in private and public-sector organisations across the region. We love this idea and CERN has been signed up to a similar scheme - Bike to Work - for several years. That’s why we’ve decided that CERN should join the Commute-A...
Intrinsic non-commutativity of closed string theory
Freidel, Laurent; Leigh, Robert G.; Minic, Djordje
2017-09-01
We show that the proper interpretation of the cocycle operators appearing in the physical vertex operators of compactified strings is that the closed string target is noncommutative. We track down the appearance of this non-commutativity to the Polyakov action of the flat closed string in the presence of translational monodromies (i.e., windings). In view of the unexpected nature of this result, we present detailed calculations from a variety of points of view, including a careful understanding of the consequences of mutual locality in the vertex operator algebra, as well as a detailed analysis of the symplectic structure of the Polyakov string. We also underscore why this non-commutativity was not emphasized previously in the existing literature. This non-commutativity can be thought of as a central extension of the zero-mode operator algebra, an effect set by the string length scale — it is present even in trivial backgrounds. Clearly, this result indicates that the α ' → 0 limit is more subtle than usually assumed.
Modelling the relation between income and commuting distance.
Carra, Giulia; Mulalic, Ismir; Fosgerau, Mogens; Barthelemy, Marc
2016-06-01
We discuss the distribution of commuting distances and its relation to income. Using data from Denmark, the UK and the USA, we show that the commuting distance is (i) broadly distributed with a slow decaying tail that can be fitted by a power law with exponent γ ≈ 3 and (ii) an average growing slowly as a power law with an exponent less than one that depends on the country considered. The classical theory for job search is based on the idea that workers evaluate the wage of potential jobs as they arrive sequentially through time, and extending this model with space, we obtain predictions that are strongly contradicted by our empirical findings. We propose an alternative model that is based on the idea that workers evaluate potential jobs based on a quality aspect and that workers search for jobs sequentially across space. We also assume that the density of potential jobs depends on the skills of the worker and decreases with the wage. The predicted distribution of commuting distances decays as 1/r(3) and is independent of the distribution of the quality of jobs. We find our alternative model to be in agreement with our data. This type of approach opens new perspectives for the modelling of mobility. © 2016 The Author(s).
Non-topological non-commutativity in string theory
Energy Technology Data Exchange (ETDEWEB)
Guttenberg, S. [NCSR Demokritos, INP, Patriarchou Gregoriou and Neapoleos Str., 15310 Agia Paraskevi Attikis (Greece); Herbst, M. [CERN, 1211 Geneva 23 (Switzerland); Kreuzer, M. [Institute for Theoretical Physics, TU Wien, Wiedner Hauptstr. 8-10, 1040 Vienna (Austria); Rashkov, R. [Erwin Schroedinger Institute for Mathematical Physics, Boltzmanngasse 9, 1090 Vienna (Austria)
2008-04-15
Quantization of coordinates leads to the non-commutative product of deformation quantization, but is also at the roots of string theory, for which space-time coordinates become the dynamical fields of a two-dimensional conformal quantum field theory. Appositely, open string diagrams provided the inspiration for Kontsevich's solution of the long-standing problem of quantization of Poisson geometry by virtue of his formality theorem. In the context of D-brane physics non-commutativity is not limited, however, to the topological sector. We show that non-commutative effective actions still make sense when associativity is lost and establish a generalized Connes-Flato-Sternheimer condition through second order in a derivative expansion. The measure in general curved backgrounds is naturally provided by the Born-Infeld action and reduces to the symplectic measure in the topological limit, but remains non-singular even for degenerate Poisson structures. Analogous superspace deformations by RR-fields are also discussed. (Abstract Copyright [2008], Wiley Periodicals, Inc.)
Dissimilarity for functional data clustering based on smoothing parameter commutation.
Tzeng, ShengLi; Hennig, Christian; Li, Yu-Fen; Lin, Chien-Ju
2017-01-01
Many studies measure the same type of information longitudinally on the same subject at multiple time points, and clustering of such functional data has many important applications. We propose a novel and easy method to implement dissimilarity measure for functional data clustering based on smoothing splines and smoothing parameter commutation. This method handles data observed at regular or irregular time points in the same way. We measure the dissimilarity between subjects based on varying curve estimates with pairwise commutation of smoothing parameters. The intuition is that smoothing parameters of smoothing splines reflect the inverse of the signal-to-noise ratios and that when applying an identical smoothing parameter the smoothed curves for two similar subjects are expected to be close. Our method takes into account the estimation uncertainty using smoothing parameter commutation and is not strongly affected by outliers. It can also be used for outlier detection. The effectiveness of our proposal is shown by simulations comparing it to other dissimilarity measures and by a real application to methadone dosage maintenance levels.
Katarina Anthony
2015-01-01
A new LHCb programme is delving into uncharted waters for the LHC: exploring how protons interact with noble gases inside the machine pipe. While, at first glance, it may sound risky for the overall quality of the vacuum in the machine, the procedure is safe and potentially very rich in rewards. The results could uncover the high-energy helium-proton cross-section (with all the implications thereof), explore new boundaries of the quark-gluon plasma and much more. As the beam passes through LHCb, interactions with neon gas allow the experiment to measure the full beam profile. In this diagram, beam 1 (blue) and beam 2 (red) are measured by the surrounding VELO detector. It all begins with luminosity. In 2011, LHCb set out to further improve its notoriously precise measurements of the beam profile, using the so-called Beam-Gas Imaging (BGI) method. BGI does exactly what it says on the tin: a small amount of gas is inserted into the vacuum, increasing the rate of collisions around the interaction ...
Gröbner, Oswald
1999-01-01
The Large Hadron Collider (LHC) project, now in the advanced construction phase at CERN, comprises two proton storage rings with colliding beams of 7-TeV energy. The machine is housed in the existing LEP tunnel with a circumference of 26.7 km and requires a bending magnetic field of 8.4 T with 14-m long superconducting magnets. The beam vacuum chambers comprise the inner 'cold bore' walls of the magnets. These magnets operate at 1.9 K, and thus serve as very good cryo-pumps. In order to reduce the cryogenic power consumption, both the heat load from synchrotron radiation emitted by the proton beams and the resistive power dissipation by the beam image currents have to be absorbed on a 'beam screen', which operates between 5 and 20 K and is inserted inside the vacuum chamber. The design of this beam screen represents a technological challenge in view of the numerous and often conflicting requirements and the very tight mechanical tolerances imposed. The synchrotron radiation produces strong outgassing from the...
Tumwesigye, Alex Behakanira; Silvestrov, Sergei
2014-12-01
T. Persson and S. D. Sivestrov investigated representations of operators satisfying the relation XX* = F(X*X) in connection with periodic points and orbits of the map F. In particular they derived commutativity conditions for two monomials in operators A and B on a Hilbert space, satisfying the relation AB = BF(A). In this article, we shall apply their results to special one-dimensional dynamical systems and and give an explicit description of the interplay between periodic orbits of one-dimensional piecewise polynomial maps and commutativity of monomials for special operators A and B. Furthermore, we shall apply our results to derive conditions on β for the special case when Fβ is the β-shift dynamical system.
Vacuum science, technology, and applications
Naik, Pramod K
2018-01-01
Vacuum plays an important role in science and technology. The study of interaction of charged particles, neutrals and radiation with each other and with solid surfaces requires a vacuum environment for reliable investigations. Vacuum has contributed immensely to advancements made in nuclear science, space, metallurgy, electrical/electronic technology, chemical engineering, transportation, robotics and many other fields. This book is intended to assist students, scientists, technicians and engineers to understand the basics of vacuum science and technology for application in their projects. The fundamental theories, concepts, devices, applications, and key inventions are discussed.
Nano-fillers to tune Young's modulus of silicone matrix
Xia, Lijin; Xu, Zhonghua; Sun, Leming; Caveney, Patrick M.; Zhang, Mingjun
2013-04-01
In this study, we investigated nanoparticles, nanofibers, and nanoclays for their filler effects on tuning the Young's modulus of silicone matrix, a material with broad in vivo applications. Nano-fillers with different shapes, sizes, and surface properties were added into silicone matrix, and then their filler effects were evaluated through experimental studies. It was found that spherical nanoparticles could clearly improve Young's modulus of the silicone matrix, while nanoclays and carbon nanofibers had limited effects. Smaller spherical nanoparticles were better in performance compared to larger nanoparticles. In addition, enhanced distribution of the nanoparticles in the matrix has been observed to improve the filler effect. In order to minimize toxicity of the nanoparticles for in vivo applications, spherical nanoparticles coated with amine, acid, or hydroxide groups were also investigated, but they were found only to diminish the filler effect of nanoparticles. This study demonstrated that spherical nanoparticles could serve as fillers to tune Young's modulus of silicone matrix for potential applications in medicine.
Determination of the elastic modulus of snow via acoustic measurements
Gerling, Bastian; van Herwijnen, Alec; Löwe, Henning
2016-04-01
The elastic modulus of snow is a key quantity from the viewpoint of avalanche research and forecasting, snow engineering or materials science in general. Since it is a fundamental property, many measurements have been reported in the literature. Due to differences in measurement methods, there is a lot of variation in the reported values. Especially values derived via computer tomography (CT) based numerical calculations using finite element methods are not corresponding to the results of other methods. The central issue is that CT based moduli are purely elastic whereas other methods may include viscoelastic deformation. In order to avoid this discrepancy we derived the elastic modulus of snow via wave propagation measurements and compared our results with CT based calculations. We measured the arrival times of acoustic pulses propagating through the snow samples to determine the P-wave velocity and in turn derive the elastic modulus along the direction of wave propagation. We performed a series of laboratory experiments to derive the P-wave modulus of snow in relation to density. The P-wave modulus ranged from 10 to 280 MPa for a snow density between 150 and 370 kg/m^3;. The moduli derived from the acoustic measurements correlated well with the CT-based values and both exhibited a power law trend over the entire density range. Encouraged by these results we used the acoustic method to investigate the temporal evolution of the elastic modulus. The rate of increase was very close to values mentioned in literature on the sintering rate of snow. Overall, our results are a first but important step towards a new measurement method to attain the elastic properties of snow.
Hybrid generalized Bosbach and Rie c̆ an states on non-commutative residuated lattices
Ma, Zhen Ming; Yang, Wei
2016-08-01
Generalized Bosbach and Rie c̆ an states, which are useful for the development of an algebraic theory of probabilistic models for commutative or non-commutative fuzzy logics, have been investigated in the literature. In this paper, a new way arising from generalizing residuated lattice-based filters from commutative case to non-commutative one is applied to introduce new notions of generalized Bosbach and Rie c̆ an states, which are called hybrid ones, on non-commutative residuated lattices is provided, and the relationships between hybrid generalized states and those existing ones are studied, examples show that they are different. In particular, two problems from L.C. Ciungu, G. Georgescu, and C. Mure, "Generalized Bosbach States: Part I" (Archive for Mathematical Logic 52 (2013):335-376) are solved, and properties of hybrid generalized states, which are similar to those on commutative residuated lattices, are obtained without the condition "strong".
Morckel, Victoria; Terzano, Kathryn
2014-01-01
This study examines the relationships between physical activity, travel attitudes, commute mode choice, and perceived neighborhood characteristics. A recent study found that people who walk or bike during their commute exercise more outside of the commute than do people who commute by mass transit or car. The current study seeks to explain what might account for this relationship, using ANOVA models (Method) conducted on survey data from 3 cities. Perceived neighborhood characteristics and travel attitudes influence participants' reported physical activity levels both during the commute and outside of the commute. While the study does not establish causality, the results provide some support for the notion that policy makers interested in increasing physical activity levels should consider changing not only the physical environment, but also perceived neighborhood characteristics and travel attitudes.
Temperature, Frequency and Young’s Modulus of a Wineglass
Directory of Open Access Journals (Sweden)
Amitta Miller
2015-01-01
Full Text Available A crystal soda-lime wineglass, heated to temperatures ranging from 25 °C to 150 °C, was tapped and the frequency recorded. It was shown that the relative change in the frequency at different temperatures can be used to determine the effect of temperature on Young’s Modulus of the glass. This simple method of tapping a wineglass is proposed as an effective way of determining the relative effect of temperature on Young’ Modulus of glass.
New insights into the Young's modulus of staggered biological composites.
Bar-On, Benny; Wagner, H Daniel
2013-03-01
This communication presents a simplified "mechanics-of-materials" approach for describing the mechanics of staggered composite architectures, such as those arising in a variety of biological tissues. This analysis calculates the effective modulus of the bio-composite and provides physical insights into its elastic behavior. Simplified expressions for high- and low-mineralized tissues are then proposed and the effects of the mineral thickness ratio and aspect ratio on the modulus are demonstrated. Copyright © 2012 Elsevier B.V. All rights reserved.
Young modulus dependence of nanoscopic friction coefficient in hard coatings
Riedo, E.; Brune, H.
2003-01-01
We present an atomic force microscope study of nanoscopic sliding friction on diamond, diamond-like carbon, and on three CrN thin films with varying hardness obtained by different growth temperatures. For the CrN films, we show that the changes in the friction coefficient can be traced back to variations of the Young modulus. More generally, we show for all samples investigated and in wearless regime, that the nanoscopic friction coefficient is directly linked to the Young modulus. (C) 2003 A...
The dynamic bulk modulus of three glass-forming liquids
DEFF Research Database (Denmark)
Niss, Kristine; Christensen, Tage Emil; Dyre, J. C.
2014-01-01
We present dynamic adiabatic bulk modulus data for three organic glass-forming liquids: two van der Waal's liquids, trimethyl-pentaphenyl-trisiloxane (DC705) and dibuthyl phtalate (DBP), and one hydrogen-bonded liquid, 1,2-propanediol (PD). All three liquids are found to obey time-temperature sup......We present dynamic adiabatic bulk modulus data for three organic glass-forming liquids: two van der Waal's liquids, trimethyl-pentaphenyl-trisiloxane (DC705) and dibuthyl phtalate (DBP), and one hydrogen-bonded liquid, 1,2-propanediol (PD). All three liquids are found to obey time...
Are commuting and residential mobility decisions simultaneous? : the case of Catalonia (Spain)
Romaní Fernández, Javier, 1969-; Suriñach Caralt, Jordi; Artís Ortuño, Manuel
2001-01-01
In this paper we study the commuting and moving decisions of workers in Catalonia (Spain) and its evolution in the 1986-1996 period. Using a microdata sample from the 1991 Spanish Population Census, we estimate a simultaneous, discrete choice model of commuting and moves, thus indirectly addressing the home and job location decisions. The econometrical framework is a simultaneous, binary probit model with a commute equation and a move equation
Page, Nadine C; Nilsson, Viktor O
2016-01-01
Objective: This paper describes a behavior change intervention that encourages active commuting using electrically assisted bikes (e-bikes) for health promotion in the workplace. This paper presents the preliminary findings of the intervention's impact on improving employee well-being and organizational behavior, as an indicator of potential business success. Method: Employees of a UK-based organization participated in a workplace travel behavior change intervention and used e-bikes as an active commuting mode; this was a change to their usual passive commuting behavior. The purpose of the intervention was to develop employee well-being and organizational behavior for improved business success. We explored the personal benefits and organizational co-benefits of active commuting and compared these to a travel-as-usual group of employees who did not change their behavior and continued taking non-active commutes. Results: Employees who changed their behavior to active commuting reported more positive affect, better physical health and more productive organizational behavior outcomes compared with passive commuters. In addition, there was an interactive effect of commuting mode and commuting distance: a more frequent active commute was positively associated with more productive organizational behavior and stronger overall positive employee well-being whereas a longer passive commute was associated with poorer well-being, although there was no impact on organizational behavior. Conclusion: This research provides emerging evidence of the value of an innovative workplace health promotion initiative focused on active commuting in protecting and improving employee well-being and organizational behavior for stronger business performance. It considers the significant opportunities for organizations pursuing improved workforce well-being, both in terms of employee health, and for improved organizational behavior and business success.
Djurhuus, Sune; Hansen, Henning Sten; Aadahl, Mette; Glümer, Charlotte
2014-01-01
Background: Active commuters have lower risk of chronic disease. Understanding which of the, to some extent, modifiable characteristics of public transportation that facilitate its use is thus important in a public health perspective. The aim of the study was to examine the association between individual public transportation accessibility and self-reported active commuting, and whether the associations varied with commute distance, age, and gender. Methods: Twenty-eight thousand nine hund...
Directory of Open Access Journals (Sweden)
Sune eDjurhuus
2014-11-01
Full Text Available Background: Active commuters have lower risk of chronic disease. Understanding which of the, to some extent, modifiable characteristics of public transportation that facilitate its use is thus important in a public health perspective. The aim of the study was to examine the association between individual public transportation accessibility and self-reported active commuting, and whether the associations varied with commute distance, age and gender. Methods: 28,928 commuters in the Capital Region of Denmark reported self-reported time spent either walking or cycling to work or study each day and the distance to work or study. Data were obtained from the Danish National Health Survey collected in February to April 2010. Individual accessibility by public transportation was calculated using a multimodal network in a GIS. Multilevel logistic regression was used to analyze the association between accessibility, expressed as access area, and being an active commuter.Results: Public transport accessibility area based on all stops within walking and cycling distance was positively associated with being an active commuter. Distance to work, age and gender modified the associations. Residing within 10 km commuting distance and in areas of high accessibility was associated with being an active commuter and meeting the recommendations of physical activity. For the respondents above 29 years, Individual public transportation accessibility was positively associated with being an active commuter. Women having high accessibility had significantly higher odds of being an active commuter compared to having a low accessibility. For men the associations were insignificant.Conclusions: This study extends the knowledge about the driving forces of using public transportation for commuting by examining the individual public transportation accessibility. Findings suggest that transportation accessibility supports active commuting and planning of improved public transit
Vacuum energy sequestering and graviton loops
Kaloper, Nemanja; Padilla, Antonio
2017-01-01
We recently formulated a local mechanism of vacuum energy sequester. This mechanism automatically removes all matter loop contributions to vacuum energy from the stress energy tensor which sources the curvature. Here we adapt the local vacuum energy sequestering mechanism to also cancel all the vacuum energy loops involving virtual gravitons, in addition to the vacuum energy generated by matter fields alone.
Price, G.W.
1954-08-01
A protector device is described for use in controlling the pressure within a cyclotron. In particular, an electrical circuit functions to actuate a vacuum pump when a predetermined low pressure is reached and disconnect the pump when the pressure increases abcve a certain value. The principal feature of the control circuit lies in the use of a voltage divider network at the input to a relay control tube comprising two parallel, adjustable resistances wherein one resistor is switched into the circuit when the relay connects the pump to a power source. With this arrangement the relay is energized at one input level received from a sensing element within the cyclotron chamber and is de-energized when a second input level, representing the higher pressure limit, is reached.
Railway-controller-perceived mental work load, cognitive failure and risky commuting.
Elfering, Achim; Grebner, Simone; Haller, Martina
2012-01-01
This questionnaire study tests cognitive failures as a mediator of the potential influence of mental work demands and conscientiousness on risky commuting. Participants were 104 railway-controllers (19% female). Failure of memory, attention regulation and action execution were assessed with the Workplace Cognitive Failure (WCF) scale. Mental work demands were measured by the Instrument for Stress-Oriented Task Analysis (ISTA). A structural equation model testing WCF as the mediator of (1) the relationship between mental work demands and risky commuting (p < 0.05) and (2) the link between conscientiousness and risky commuting (p < 0.05) fitted well with empirical data. In railway-controllers frequent interruptions, time pressure, and high concentration demands are likely to increase cognitive load and thereby boost WCF during work and also during commuting, thereby reducing commuting safety. The results underline the need for work redesign to improve commuting safety. Commuting accidents occur frequently and at high cost. This study shows that mental work demands of railway staff are related to cognitive failure and risky commuting behaviour such as failing to give way and overlooking stop signs. Primary prevention of commuting accidents should include reduction of mental workload.
Factors Affecting of Commuter Migrant Traders Income from Tanah Mas Village to Palembang City
Directory of Open Access Journals (Sweden)
Bambang Bemby Soebyakto
2016-09-01
Full Text Available This study aimed to analyze the factors that affect the income of migrant traders in the informal sector who do commuting of Tanah Mas village to the Palembang city. This research was done using descriptive quantitative primary data. This research was conducted at the Tanah Mas village. Populations of migrant populations who do commuting are 398 people. Proportional stratified random sampling is selected to determine of sample. Samples are 100 migrants’ commuter traders. Multiple regression analysis was used to measure the effect of independent variables (marital status, number of family, length of work, mode of transportation, type of merchandise, and motivation of commuter traders on the dependent variable (commuter trader income . The study found that marital status, number of family, length of work, mode of transportation, type of merchandise, and motivation commuter traders have significantly affect to migrant income the Tanah Mas village to Palembang city. Partially, the number of family, mode of transportation, and the type of merchandise have significantly affect to commuter traders income, whereas marital status, length of work, and motivation commuter trader have not significantly affect the commuter trader income.
Potential health impact of switching from car to public transportation when commuting to work.
Morabia, Alfredo; Mirer, Franklin E; Amstislavski, Tashia M; Eisl, Holger M; Werbe-Fuentes, Jordan; Gorczynski, John; Goranson, Chris; Wolff, Mary S; Markowitz, Steven B
2010-12-01
We assessed humidity-corrected particulate matter (PM(2.5)) exposure and physical activity (using global positioning system monitors and diaries) among 18 people who commuted by car to Queens College, New York, New York, for 5 days, and then switched to commuting for the next 5 days via public transportation. The PM(2.5) differed little between car and public transportation commutes (1.41 μg/M(3)·min; P = .226). Commuting by public transportation rather than by car increased energy expenditure (+124 kcal/day; P < .001) equivalent to the loss of 1 pound of body fat per 6 weeks.
Non-commutative gauge gravity: second-order correction and scalar particle creation
Energy Technology Data Exchange (ETDEWEB)
Zaim, Slimane [Departement de Physique, Faculte des Sciences, Universite de Batna (Algeria); Khodja, Lamine, E-mail: zaimslimane@yahoo.f [Departement de Physique, Faculte des Sciences Exactes, Universite Mentouri, Constantine (Algeria)
2010-05-01
We construct a non-commutative gauge theory for a charged scalar field and verify its invariance under local Poincare and general coordinate transformations. We derive a general Klein-Gordon equation up to the second order of the non-commutativity parameter using the general modified field equation. As an application, we choose the Bianchi I universe and use the Seiberg-Witten maps to obtain the deformed non-commutative metric and study a particle production process. We show that non-commutativity plays the same role as an electric field, gravity and chemical potential.
Abdominal intrauterine vacuum aspiration.
Tjalma, W A A
2014-01-01
Evaluating and "cleaning" of the uterine cavity is probably the most performed operation in women. It is done for several reasons: abortion, evaluation of irregular bleeding in premenopausal period, and postmenopausal bleeding. Abortion is undoubtedly the number one procedure with more than 44 million pregnancies terminated every year. This procedure should not be underestimated and a careful preoperative evaluation is needed. Ideally a sensitive pregnancy test should be done together with an ultrasound in order to confirm a uterine pregnancy, excluding extra-uterine pregnancy, and to detect genital and/or uterine malformations. Three out of four abortions are performed by surgical methods. Surgical methods include a sharp, blunt, and suction curettage. Suction curettage or vacuum aspiration is the preferred method. Despite the fact that it is a relative safe procedure with major complications in less than one percent of cases, it is still responsible for 13% of all maternal deaths. All the figures have not declined in the last decade. Trauma, perforation, and bleeding are a danger triage. When there is a perforation, a laparoscopy should be performed immediately, in order to detect intra-abdominal lacerations and bleeding. The bleeding should be stopped as soon as possible in order to not destabilize the patient. When there is a perforation in the uterus, this "entrance" can be used to perform the curettage. This is particularly useful if there is trauma of the isthmus and uterine wall, and it is difficult to identify the uterine canal. A curettage is a frequent performed procedure, which should not be underestimated. If there is a perforation in the uterus, then this opening can safely be used for vacuum aspiration.
ULTRARAPID VACUUM-MICROWAVE HISTOPROCESSING
KOK, LP; BOON, ME
A novel histoprocessing method for paraffin sections is presented in which the combination of vacuum and microwave exposure is the key element. By exploiting the decrease in boiling temperature under vacuum, the liquid molecules in the tissues have been successfully extracted and exchanged at
Vacuum Technology for Superconducting Devices
Chiggiato, P
2014-01-01
The basic notions of vacuum technology for superconducting applications are presented, with an emphasis on mass and heat transport in free molecular regimes. The working principles and practical details of turbomolecular pumps and cryopumps are introduced. The specific case of the Large Hadron Collider’s cryogenic vacuum system is briefly reviewed.
Study on strength, elastic modulus of artifical lightweight aggregate concrete
Kakizaki, M.
1982-04-01
Aggregate strength of artificial lightweight concrete and concrete used with this artificial lightweight aggregate can be expected to have nearly the same strength as normal weight concrete. An experimental study of properties of concrete strength and correlation between compressive and tensile and flexural strengths and elastic modulus of its concrete was made.
Determination of the modulus of elasticity of the human cornea.
Elsheikh, Ahmed; Wang, Defu; Pye, David
2007-10-01
To determine the material behavior of the human cornea in the form of simple relationships between the modulus of elasticity and intraocular pressure (IOP) and to establish the effect of age on the material behavior. Human corneal specimens with age between 50 and 95 years were tested under inflation conditions to determine their behavior. The corneas were subjected to two extreme load rates to represent dynamic and static loading conditions. The pressure-deformation results were analyzed using shell theory to derive the relationship between the modulus of elasticity and IOP. The corneas demonstrated a nonlinear hyperelastic behavior pattern with an initial low stiffness stage and a final high stiffness stage. Despite the nonlinearity of the pressure deformation results, the relationship between the modulus of elasticity and the applied pressure was almost linear. A considerable increase was noted in the values of the modulus of elasticity associated with both age and load rate. General equations were derived to calculate the values of the secant and tangent moduli of elasticity in terms of IOP for any age greater than 50 years, and these equations are presented in a simple form suitable for use in numerical simulations. Adequate representation of corneal material behavior is essential for the accurate predictive modeling of corneal biomechanics. The material models developed in this work could be implemented in numerical simulations of refractive surgery procedures, corneal shape changes due to contact lens wear, and other applications.
Effect of bulk modulus on performance of a hydrostatic transmission ...
Indian Academy of Sciences (India)
) and fuzzy controllers on the angular velocity of a hydrostatic transmission system by means of Matlab-Simulink. A very novel aspect is that it includes the analysis of the effect of bulk modulus on system control. Simulation results demonstrates ...
Quantitative photoacoustic elastography of Young's modulus in humans
Hai, Pengfei; Zhou, Yong; Gong, Lei; Wang, Lihong V.
2017-03-01
Elastography can noninvasively map the elasticity distribution of biological tissue, which is often altered in pathological states. In this work, we report quantitative photoacoustic elastography (QPAE), capable of measuring Young's modulus of human tissue in vivo. By combining photoacoustic elastography with a stress sensor having known stress-strain behavior, QPAE can simultaneously measure strain and stress, from which Young's modulus is calculated. We first applied QPAE to quantify the Young's modulus of tissue-mimicking agar phantoms with different concentrations. The measured values fitted well with both the empirical expectations based on the agar concentrations and those measured in independent standard compression tests. We then demonstrated the feasibility of QPAE by measuring the Young's modulus of human skeletal muscle in vivo. The data showed a linear relationship between muscle stiffness and loading. The results proved that QPAE can noninvasively quantify the absolute elasticity of biological tissue, thus enabling longitudinal imaging of tissue elasticity. QPAE can be exploited for both preclinical biomechanics studies and clinical applications.
Device for measuring elastic modulus of superconducting coils (See 7903169)
1979-01-01
This device was made to measure elastic modulus of the Po dipole superconducting coils. More elaborated devices, but based on the same concept, were later used to measure the apparent elastic moduli of the LHC superconducting magnet coils. See also 7903169, 7901386.
Determination of bending modulus of elasticity of Pterygota ...
African Journals Online (AJOL)
Two different international testing norms, DIN52186 (1978) and ISO8375 (1985) were used to determine the bending modulus of elasticity (MOE) of Pterygota macrocarpa K. Schum (Kyere) and Piptadeniastrum africanum (Dahoma). The results from the two testing norms for each timber species were highly correlated, with ...
Estimate of K-functionals and modulus of smoothness constructed ...
Indian Academy of Sciences (India)
Introduction and preliminaries. In [2], Belkina and Platonov proved the equivalence theorem for a K-functional and a modulus of smoothness for the Dunkl transform in the Hilbert space L2(R, |x|2α+1. ), α > −1/2, using a Dunkl translation operator. In this paper, we prove the analog of this result (see [2]) in the Hilbert space.
Connecting Jacobi elliptic functions with different modulus parameters
Indian Academy of Sciences (India)
Abstract. The simplest formulas connecting Jacobi elliptic functions with different modulus parameters were first obtained over two hundred years ago by John Landen. His approach was to change integration variables in elliptic integrals. We show that. Landen's formulas and their subsequent generalizations can also be ...
Device to measure elastic modulus of superconducting windings
CERN PhotoLab
1979-01-01
This device was made to measure elastic modulus of the Po dipole superconducting coils. More elaborated devices, but based on the same concept, were later used to measure the apparent elastic moduli of the LHC superconducting magnet coils. See also 7903547X, 7901386.
High elastic modulus nanopowder reinforced resin composites for dental applications
Wang, Yijun
2007-12-01
Dental restorations account for more than $3 billion dollars a year on the market. Among them, all-ceramic dental crowns draw more and more attention and their popularity has risen because of their superior aesthetics and biocompatibility. However, their relatively high failure rate and labor-intensive fabrication procedure still limit their application. In this thesis, a new family of high elastic modulus nanopowder reinforced resin composites and their mechanical properties are studied. Materials with higher elastic modulus, such as alumina and diamond, are used to replace the routine filler material, silica, in dental resin composites to achieve the desired properties. This class of composites is developed to serve (1) as a high stiffness support to all-ceramic crowns and (2) as a means of joining independently fabricated crown core and veneer layers. Most of the work focuses on nano-sized Al2O3 (average particle size 47 nm) reinforcement in a polymeric matrix with 50:50 Bisphenol A glycidyl methacrylate (Bis-GMA): triethylene glycol dimethacrylate (TEGDMA) monomers. Surfactants, silanizing agents and primers are examined to obtain higher filler levels and enhance the bonding between filler and matrix. Silane agents work best. The elastic modulus of a 57.5 vol% alumina/resin composite is 31.5 GPa compared to current commercial resin composites with elastic modulus alumina, diamond/resin composites are studied. An elastic modulus of about 45 GPa is obtained for a 57 vol% diamond/resin composite. Our results indicate that with a generally monodispersed nano-sized high modulus filler, relatively high elastic modulus resin-based composite cements are possible. Time-dependent behavior of our resin composites is also investigated. This is valuable for understanding the behavior of our material and possible fatigue testing in the future. Our results indicate that with effective coupling agents and higher filler loading, viscous flow can be greatly decreased due to the
Heinrici, Axel; Bjelajac, Goran; Jonkers, Jeroen; Jakobs, Stefan; Olschok, Simon; Reisgen, Uwe
2017-02-01
Research and development carried out by the ISF Welding and Joining Institute of RWTH Aachen University has proven that combining high power laser and low vacuum atmosphere provides a welding performance and quality, which is comparable to electron beam welding. The developed welding machines are still using a beam forming which takes place outside the vacuum and the focusing laser beam has to be introduced to the vacuum via a suitable window. This inflexible design spoils much of the flexibility of modern laser welding. With the target to bring a compact, lightweight flying optics with flexible laser transport fibers into vacuum chambers, a high power fiber-fiber coupler has been adapted by II-VI HIGHYAG that includes a reliable vacuum interface. The vacuum-fiber-fiber coupler (V-FFC) is tested with up to 16 kW sustained laser power and the design is flexible in terms of a wide variety of laser fiber plug systems and vacuum flanges. All that is needed to implement the V-FFC towards an existing or planned vacuum chamber is an aperture of at least 100 mm (4 inch) diameter with any type of vacuum or pressure flange. The V-FFC has a state-of-the-art safety interface which allows for fast fiber breakage detection for both fibers (as supported by fibers) by electric wire breakage and short circuit detection. Moreover, the System also provides connectors for cooling and electric signals for the laser beam optics inside the vacuum. The V-FFC has all necessary adjustment options for coupling the laser radiation to the receiving fiber.
49 CFR 570.56 - Vacuum brake assist unit and vacuum brake system.
2010-10-01
... 49 Transportation 6 2010-10-01 2010-10-01 false Vacuum brake assist unit and vacuum brake system... Vehicles With GVWR of More Than 10,000 Pounds § 570.56 Vacuum brake assist unit and vacuum brake system. The following requirements apply to vehicles with vacuum brake assist units and vacuum brake systems...
Investigation of the elastic modulus of SSC coils
Energy Technology Data Exchange (ETDEWEB)
Markley, F.; Kerby, J.; Sizemore, B.; Khoun, C.; King, T.
1991-03-01
The Materials Development Laboratory at Fermilab has been conducting experiments on the mechanical properties of superconducting coils. Two of these measurements were designed to measure the elastic modulus of actual SSC coils in an effort to increase the precision of previously reported data. The first experiment utilizes a fixture redesigned for increased stiffness, in an attempt to reduce uncertainty in the data. As in the previous fixture of this type, the inner coil radius has been left unconstrained. The second fixture constrains the coil on all sides, allowing for the determination of the radial and azimuthal components of the cured coil modulus. A finite element model of the first test arrangement was also created to predict the compliance of the fixture, and compare numerical predictions with the experimental data. The results from this fixture suggest that the coil modulus is higher than previously reported, at 1.43{plus minus}0.03{times}10{sup 10} Pa (2.08{plus minus}.05{times}10{sup 6} psi). The main difference between the two experiments were the compliance of the fixture, which was found to have been seriously underestimated in last years test. Results from the second fixture suggest a coil modulus of 8.48{plus minus}0.82{times}10{sup 9} Pa (1.23{plus minus}0.12{times}10{sup 6} psi) for the azimuthal modulus, and between 8.96{plus minus}0.822{times}10{sup 9} Pa (1.3{plus minus}0.12{times}10{sup 6} psi) at lower loads and 1.12{plus minus}0.24{times}10{sup 10} Pa (1.63{plus minus}0.35{times}10{sup 6} psi) at higher loads in the radial direction. For a constrained coil, little difference is noted between the radial and azimuthal moduli of the coil. 2 refs., 8 figs.
Investigation of the elastic modulus of SSC coils
Energy Technology Data Exchange (ETDEWEB)
Markley, F.; Kerby, J.; Sizemore, B.; Khoun, C.; King, T.
1991-03-01
The Materials Development Laboratory at Fermilab has been conducting experiments on the mechanical properties of superconducting coils. Two of these measurements were designed to measure the elastic modulus of actual SSC coils in an effort to increase the precision of previously reported data. The first experiment utilizes a fixture redesigned for increased stiffness, in an attempt to reduce uncertainty in the data. As in the previous fixture of this type, the inner coil radius has been left unconstrained. The second fixture constrains the coil on all sides, allowing for the determination of the radial and azimuthal components of the cured coil modulus. A finite element model of the first test arrangement was also created to predict the compliance of the fixture, and compare numerical predictions with the experimental data. The results from this fixture suggest that the coil modulus is higher than previously reported, at 1.43{plus_minus}0.03{times}10{sup 10} Pa (2.08{plus_minus}.05{times}10{sup 6} psi). The main difference between the two experiments were the compliance of the fixture, which was found to have been seriously underestimated in last years test. Results from the second fixture suggest a coil modulus of 8.48{plus_minus}0.82{times}10{sup 9} Pa (1.23{plus_minus}0.12{times}10{sup 6} psi) for the azimuthal modulus, and between 8.96{plus_minus}0.822{times}10{sup 9} Pa (1.3{plus_minus}0.12{times}10{sup 6} psi) at lower loads and 1.12{plus_minus}0.24{times}10{sup 10} Pa (1.63{plus_minus}0.35{times}10{sup 6} psi) at higher loads in the radial direction. For a constrained coil, little difference is noted between the radial and azimuthal moduli of the coil. 2 refs., 8 figs.
Zeng, Jie; Qi, Tianqi; Wang, Shu; Zhang, Tianjiao; Zhou, Weiyan; Zhao, Haijian; Ma, Rong; Zhang, Jiangtao; Yan, Ying; Dong, Jun; Zhang, Chuanbao; Chen, Wenxiang
2017-12-01
The aim of the current study was to evaluate the commutability of commercial control materials and human serum pools and to investigate the suitability of the materials for the external quality assessment (EQA) of serum apolipoprotein A-I (apo A-I) measurement. The Clinical and Laboratory Standards Institute (CLSI) EP14-A3 protocol was used for the commutability study. Apo A-I concentrations in two levels of commercial control materials used in EQA program, two fresh-frozen human serum pools (FSPs) and two frozen human serum pools prepared from residual clinical specimens (RSPs) were measured along with 50 individual samples using nine commercial assays. Measurement results of the 50 individual samples obtained with different assays were pairwise analyzed by Deming regression, and 95% prediction intervals (PIs) were calculated. The commutability of the processed materials was evaluated by comparing the measurement results of the materials with the limits of the PIs. The FSP-1 was commutable for all the 36 assay pairs, and FSP-2 was commutable for 30 pairs; RSP-1 and RSP-2 showed commutability for 27/36 and 22/36 assay pairs, respectively, whereas the two EQA materials were commutable only for 4/36 and 5/36 assay pairs, respectively. Non-commutability of the tested EQA materials has been observed among current apo A-I assays. EQA programs need either to take into account the commutability-related biases in the interpretation of the EQA results or to use more commutable materials. Frozen human serum pools were commutable for most of the assays.
Guell, C; Panter, J; Jones, N R; Ogilvie, D
2012-07-01
Fostering physical activity is an established public health priority for the primary prevention of a variety of chronic diseases. One promising population approach is to seek to embed physical activity in everyday lives by promoting walking and cycling to and from work ('active commuting') as an alternative to driving. Predominantly quantitative epidemiological studies have investigated travel behaviours, their determinants and how they may be changed towards more active choices. This study aimed to depart from narrow behavioural approaches to travel and investigate the social context of commuting with qualitative social research methods. Within a social practice theory framework, we explored how people describe their commuting experiences and make commuting decisions, and how travel behaviour is embedded in and shaped by commuters' complex social worlds. Forty-nine semi-structured interviews and eighteen photo-elicitation interviews with accompanying field notes were conducted with a subset of the Commuting and Health in Cambridge study cohort, based in the UK. The findings are discussed in terms of three particularly pertinent facets of the commuting experience. Firstly, choice and decisions are shaped by the constantly changing and fluid nature of commuters' social worlds. Secondly, participants express ambiguities in relation to their reasoning, ambitions and identities as commuters. Finally, commuting needs to be understood as an embodied and emotional practice. With this in mind, we suggest that everyday decision-making in commuting requires the tactical negotiation of these complexities. This study can help to explain the limitations of more quantitative and static models and frameworks in predicting travel behaviour and identify future research directions. Copyright © 2012 Elsevier Ltd. All rights reserved.
The poset of the nilpotent commutator of a nilpotent matrix
Khatami, Leila
2012-01-01
Let $B$ be an $n \\times n$ nilpotent matrix with entries in an infinite field $\\k$. Assume that $B$ is in Jordan canonical form with the associated Jordan block partition $P$. In this paper, we study a poset $\\mathcal{D}_P$ associated to the nilpotent commutator of $B$ and a certain partition of $n$, denoted by $\\lambda_U(P)$, defined in terms of the lengths of unions of special chains in $\\mathcal{D}_P$. Polona Oblak associated to a given partition $P$ another partition $Ob(P)$ resulting fro...
Revisiting quantum mechanics on non-commutative space-time
Nandi, Partha; Pal, Sayan Kumar; Bose, Aritra N.; Chakraborty, Biswajit
2017-11-01
We construct an effective commutative Schrödinger equation in Moyal space-time in (1 + 1) -dimension where both t and x are operator-valued and satisfy [ t ˆ , x ˆ ] = iθ. Beginning with a time-reparametrised invariant form of an action we identify the actions of various space-time coordinates and their conjugate momenta on quantum states, represented by Hilbert-Schmidt operators. Since time is also regarded as a configuration space variable, we show how an 'induced' inner product can be extracted, so that an appropriate probabilistic interpretation is obtained. We then discuss several other applications of the formalism developed so far.
Note on the Tableau Technique for Commutative Transition Systems
DEFF Research Database (Denmark)
Srba, Jirí
2002-01-01
We define a class of transition systems called effective commutative transition systems (ECTS) and show, by generalising a tableau-based proof for BPP, that strong bisimilarity between any two states of such a transition system is decidable. It gives a general technique for extending decidability...... borders of strong bisimilarity for a wide class of infinite-state transition systems. This is demonstrated for several process formalisms, namely BPP process algebra, lossy BPP processes, BPP systems with interrupt and timed-arc BPP nets....
Supergravity and Light-Like Non-commutativity
Alishahiha, M; Russo, Jorge G; Alishahiha, Mohsen; Oz, Yaron; Russo, Jorge G.
2000-01-01
We construct dual supergravity descriptions of field theories and little string theories with light-like non-commutativity. The field theories are realized on the world-volume of Dp branes with light-like NS $B$ field and M5 branes with light-like $C$ field. The little string theories are realized on the world-volume of NS5 branes with light-like RR $A$ fields. The supergravity backgrounds are closely related to the $A=0,B=0,C=0$ backgrounds. We discuss the implications of these results. We also construct dual supergravity descriptions of ODp theories realized on the worldvolume of NS5 branes with RR backgrounds.
Steve P. Verrill; Frank C. Owens; David E. Kretschmann; Rubin Shmulsky
2017-01-01
It is common practice to assume that a two-parameter Weibull probability distribution is suitable for modeling lumber properties. Verrill and co-workers demonstrated theoretically and empirically that the modulus of rupture (MOR) distribution of visually graded or machine stress rated (MSR) lumber is not distributed as a Weibull. Instead, the tails of the MOR...
Directory of Open Access Journals (Sweden)
Savatier Vincent
2016-01-01
Limit pressure and Ménard pressuremeter modulus variation with respect to drought in silty clay situated in water-table fluctuation area. Finally, we will try to show the consequences of these stress paths for performing and interpreting pressuremeter test in unsaturated and collapsible soils.
Directory of Open Access Journals (Sweden)
E. D. Chertov
2015-01-01
Full Text Available The work is devoted to the creation of a new type of mixer to produce homogeneous mixtures of dissimilar materials applied to recycling of housing and communal services waste. The article describes the design of a dual-chamber device of the original high-temperature vacuum mixer, there investigated the processes occurring in the chambers of such devices. The results of theoretical and experimental research of the process of mixing recycled polyethylene with a mixture of "grinded food waste – Eco wool” are presented. The problem of the optimum choice of bending the curvilinear blades in the working volume of the seal, which is achieved by setting their profile in the form of involute arc of several circles of different radii, is examined . The dependences, allowing to define the limits of the changes of the main mode parameters the angular velocity of rotation of the working body of the mixer using two ways of setting the profile of the curvilinear blade mixer are obtained. Represented design of the mixer is proposed to use for a wide range of tasks associated with the mixing of the components with a strongly pronounced difference of physic al chemical properties and, in particular, in the production of composites out of housing and communal services waste.
Experimental tests of vacuum energy
CERN. Geneva
2015-01-01
While the current vacuum energy of the Universe is very small, in our standard cosmological picture it has been much larger at earlier epochs. We try to address the question of what are possible ways to try to experimentally verify this. One direction is to look for systems where vacuum energy constitutes a non-negligible fraction of the total energy, and study the properties of those. Another possibility is to focus on the epochs around cosmic phase transitions, when the vacuum energy is of the same order as the total energy. Along these lines we investigate properties of neutron stars and the imprint of phase transitions on primordial gravitational waves.
Directory of Open Access Journals (Sweden)
Dongxiang Chen
2013-01-01
commutator and iterated commutator generated by the vector-valued multilinear operator and BMO functions. By the weighted estimates for a class of new variant maximal and sharp maximal functions, the multiple weighted norm inequalities for such operators are obtained.
49 CFR 37.51 - Key stations in commuter rail systems.
2010-10-01
... 49 Transportation 1 2010-10-01 2010-10-01 false Key stations in commuter rail systems. 37.51... INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.51 Key stations in commuter rail systems... boardings exceed average station passenger boardings on the rail system by at least fifteen percent, unless...
Modeling commuter preferences for the proposed bus rapid transit in Dar-es-Salaam
Nkurunziza, A.; Zuidgeest, M.H.P.; Brussel, M.J.G.; van Maarseveen, M.F.A.M.
2012-01-01
The paper analyzes individual commuter preferences towards the proposed bus rapid transit (BRT) system in Dar-es-Salaam, Tanzania. The objective of the survey was to identify how commuters perceive and value the proposed BRT service quality attributes. A stated preference survey of potential users
Getting to High School in Baltimore: Student Commuting and Public Transportation
Stein, Marc L.; Grigg, Jeffrey; Cronister, Curt; Chavis, Celeste; Connolly, Faith
2017-01-01
This report is the first publication of a multi-year project examining the relationship between student commutes using public transportation and on-time arrival and absenteeism. This report begins to develop a basic understanding of how students commute to high school in Baltimore with a focus on those using public transportation. The report is…
New PWM method and commutation strategy for HF-link converters for fuel cells and photovoltaics
DEFF Research Database (Denmark)
Ljusev, Petar; Andersen, Michael Andreas E.
2005-01-01
This paper presents a new PWM method and commutation strategy for HF-link converters, which leads to safe commutation of the load current in the output bidirectional bridge. The proposed implementation is independent of the particular HF-link converter topology and bidirectional switch selection ...
Markee, David J.
The environmental perceptions of 144 randomly selected freshman students at a southwestern junior college were measured using the College and University Environment Scales (CUES). The sample was equally divided between male and female students, and among three groups: city commuters, rural commuters, and campus residents. Differences between group…
Non-commutative multiple-valued logic algebras
Ciungu, Lavinia Corina
2014-01-01
This monograph provides a self-contained and easy-to-read introduction to non-commutative multiple-valued logic algebras; a subject which has attracted much interest in the past few years because of its impact on information science, artificial intelligence and other subjects. A study of the newest results in the field, the monograph includes treatment of pseudo-BCK algebras, pseudo-hoops, residuated lattices, bounded divisible residuated lattices, pseudo-MTL algebras, pseudo-BL algebras and pseudo-MV algebras. It provides a fresh perspective on new trends in logic and algebras in that algebraic structures can be developed into fuzzy logics which connect quantum mechanics, mathematical logic, probability theory, algebra and soft computing. Written in a clear, concise and direct manner, Non-Commutative Multiple-Valued Logic Algebras will be of interest to masters and PhD students, as well as researchers in mathematical logic and theoretical computer science.
Commuting nonselfadjoint operators in Hilbert space two independent studies
Livšic, Moshe S
1987-01-01
Classification of commuting non-selfadjoint operators is one of the most challenging problems in operator theory even in the finite-dimensional case. The spectral analysis of dissipative operators has led to a series of deep results in the framework of unitary dilations and characteristic operator functions. It has turned out that the theory has to be based on analytic functions on algebraic manifolds and not on functions of several independent variables as was previously believed. This follows from the generalized Cayley-Hamilton Theorem, due to M.S.Livsic: "Two commuting operators with finite dimensional imaginary parts are connected in the generic case, by a certain algebraic equation whose degree does not exceed the dimension of the sum of the ranges of imaginary parts." Such investigations have been carried out in two directions. One of them, presented by L.L.Waksman, is related to semigroups of projections of multiplication operators on Riemann surfaces. Another direction, which is presented here by M.S...
Breakfast Skipping, Extreme Commutes, and the Sex Composition at Birth.
Mazumder, Bhashkar; Seeskin, Zachary
2015-01-01
A growing body of literature has shown that environmental exposures in the period around conception can affect the sex ratio at birth through selective attrition that favors the survival of female conceptuses. Glucose availability is considered a key indicator of the fetal environment, and its absence as a result of meal skipping may inhibit male survival. We hypothesize that breakfast skipping during pregnancy may lead to a reduction in the fraction of male births. Using time use data from the United States we show that women with commute times of 90 minutes or longer are 20 percentage points more likely to skip breakfast. Using U.S. census data we show that women with commute times of 90 minutes or longer are 1.2 percentage points less likely to have a male child under the age of 2. Under some assumptions, this implies that routinely skipping breakfast around the time of conception leads to a 6 percentage point reduction in the probability of a male child. Skipping breakfast during pregnancy may therefore constitute a poor environment for fetal health more generally.
Daily Commute Time Prediction Based on Genetic Algorithm
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Fang Zong
2012-01-01
Full Text Available This paper presents a joint discrete-continuous model for activity-travel time allocation by employing the ordered probit model for departure time choice and the hazard model for travel time prediction. Genetic algorithm (GA is employed for optimizing the parameters in the hazard model. The joint model is estimated using data collected in Beijing, 2005. With the developed model, departure and travel times for the daily commute trips are predicted and the influence of sociodemographic variables on activity-travel timing decisions is analyzed. Then the whole time allocation for the typical daily commute activities and trips is derived. The results indicate that the discrete choice model and the continuous model match well in the calculation of activity-travel schedule. The results also show that the genetic algorithm contributes to the optimization and thus the high accuracy of the hazard model. The developed joint discrete-continuous model can be used to predict the agenda of a simple daily activity-travel pattern containing only work, and it provides potential for transportation demand management policy analysis.
Urban routes and commuting bicyclist’s aesthetic experience
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Harpa Stefansdottir
2014-08-01
Full Text Available The present study examines whether and in what way aesthetic experience is involved in the judged quality of bicyclist’s route which they have chosen to ride between home and work. In this respect it is considered important to distinguish aesthetic experience from experience that is related to the influence of instrumental or functional features. The aesthetic impact is primarily related to features that stimulate emotional well-being when cycling. An online survey was conducted in three Nordic cities, Odense, Trondheim and Reykjavík, concentrating on cycling in different urban surroundings. The interpretation of the meanings and values associated with certain features or characteristics that influenced the commuting cyclists’ aesthetic experience is in this paper based on three theoretical viewpoints: (1 the phenomenology of perception and experience, (2 urban design theory and (3 environmental aesthetic theories and methods. The last theory involves the interpretation of experience from the environment into aesthetic meaning. The results of the survey indicate that aesthetic experience is of value to most of the respondents and is, therefore, of importance in developing the quality of bicycle routes for commuting. Greenery and contact with the natural environment and distance from motorised traffic are the most important influences on pleasurable aesthetic experience.
Tensors, !-graphs, and non-commutative quantum structures
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Aleks Kissinger
2014-12-01
Full Text Available Categorical quantum mechanics (CQM and the theory of quantum groups rely heavily on the use of structures that have both an algebraic and co-algebraic component, making them well-suited for manipulation using diagrammatic techniques. Diagrams allow us to easily form complex compositions of (coalgebraic structures, and prove their equality via graph rewriting. One of the biggest challenges in going beyond simple rewriting-based proofs is designing a graphical language that is expressive enough to prove interesting properties (e.g. normal form results about not just single diagrams, but entire families of diagrams. One candidate is the language of !-graphs, which consist of graphs with certain subgraphs marked with boxes (called !-boxes that can be repeated any number of times. New !-graph equations can then be proved using a powerful technique called !-box induction. However, previously this technique only applied to commutative (or cocommutative algebraic structures, severely limiting its applications in some parts of CQM and (especially quantum groups. In this paper, we fix this shortcoming by offering a new semantics for non-commutative !-graphs using an enriched version of Penrose's abstract tensor notation.
Examining the Link Between Public Transit Use and Active Commuting
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Melissa Bopp
2015-04-01
Full Text Available Background: An established relationship exists between public transportation (PT use and physical activity. However, there is limited literature that examines the link between PT use and active commuting (AC behavior. This study examines this link to determine if PT users commute more by active modes. Methods: A volunteer, convenience sample of adults (n = 748 completed an online survey about AC/PT patterns, demographic, psychosocial, community and environmental factors. t-test compared differences between PT riders and non-PT riders. Binary logistic regression analyses examined the effect of multiple factors on AC and a full logistic regression model was conducted to examine AC. Results: Non-PT riders (n = 596 reported less AC than PT riders. There were several significant relationships with AC for demographic, interpersonal, worksite, community and environmental factors when considering PT use. The logistic multivariate analysis for included age, number of children and perceived distance to work as negative predictors and PT use, feelings of bad weather and lack of on-street bike lanes as a barrier to AC, perceived behavioral control and spouse AC were positive predictors. Conclusions: This study revealed the complex relationship between AC and PT use. Further research should investigate how AC and public transit use are related.
Examining the link between public transit use and active commuting.
Bopp, Melissa; Gayah, Vikash V; Campbell, Matthew E
2015-04-17
An established relationship exists between public transportation (PT) use and physical activity. However, there is limited literature that examines the link between PT use and active commuting (AC) behavior. This study examines this link to determine if PT users commute more by active modes. A volunteer, convenience sample of adults (n = 748) completed an online survey about AC/PT patterns, demographic, psychosocial, community and environmental factors. t-test compared differences between PT riders and non-PT riders. Binary logistic regression analyses examined the effect of multiple factors on AC and a full logistic regression model was conducted to examine AC. Non-PT riders (n = 596) reported less AC than PT riders. There were several significant relationships with AC for demographic, interpersonal, worksite, community and environmental factors when considering PT use. The logistic multivariate analysis for included age, number of children and perceived distance to work as negative predictors and PT use, feelings of bad weather and lack of on-street bike lanes as a barrier to AC, perceived behavioral control and spouse AC were positive predictors. This study revealed the complex relationship between AC and PT use. Further research should investigate how AC and public transit use are related.
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Bryukhovetskiy AS
2015-02-01
Full Text Available Andrey S Bryukhovetskiy Center for Biomedical Technologies, Federal Research and Clinical Center for Specialized Types of Medical Assistance and Medical Technologies of the Federal Medical Biological Agency, NeuroVita Clinic of Interventional and Restorative Neurology and Therapy, Moscow, Russia Abstract: Based on the methodology of the informational approach and research of the genome, proteome, and complete transcriptome profiles of different cells in the nervous tissue of the human brain, the author proposes a new theory of information-commutation organization and architecture of the human brain which is an alternative to the conventional systemic connective morphofunctional paradigm of the brain framework. Informational principles of brain operation are defined: the modular principle, holographic principle, principle of systematicity of vertical commutative connection and complexity of horizontal commutative connection, regulatory principle, relay principle, modulation principle, “illumination” principle, principle of personalized memory and intellect, and principle of low energy consumption. The author demonstrates that the cortex functions only as a switchboard and router of information, while information is processed outside the nervous tissue of the brain in the intermeningeal space. The main structural element of information-commutation in the brain is not the neuron, but information-commutation modules that are subdivided into receiver modules, transmitter modules, and subscriber modules, forming a vertical architecture of nervous tissue in the brain as information lines and information channels, and a horizontal architecture as central, intermediate, and peripheral information-commutation platforms. Information in information-commutation modules is transferred by means of the carriers that are characteristic to the specific information level from inductome to genome, transcriptome, proteome, metabolome, secretome, and magnetome
Ham, Walter; Vijayan, Abhilash; Schulte, Nico; Herner, Jorn D.
2017-10-01
This study was designed to estimate and compare the air pollution exposures experienced by commuters in six common transportation modes utilized by California residents, and to evaluate the impact of practical exposure mitigation strategies in reducing commute exposures. We measured concentrations of fine particle matter (PM2.5), black carbon (BC), and ultrafine particles (UFP) for 161 commutes between April 2014 and November 2015 in Sacramento, CA. We collected measurements for six modes including single occupancy vehicles, high occupancy vehicles (multiple occupants), buses, light rail, train, and bicycling. The largest average concentrations for most pollutants were measured during train commutes and the lowest average concentrations were observed during light-rail commutes. Mitigation options were explored for personal vehicles, bicycling, and train commute modes. We found that ventilation settings of personal vehicles can reduce in-vehicle PM2.5, BC, and UFP concentrations by up to 75%. Similarly, bicycle route choice can reduce exposures by 15-75% with the lowest concentrations observed during commutes on dedicated bicycle paths away from traffic sources. Train commuters experienced UFP concentrations an order of magnitude greater when the locomotive engine was pulling the rail cars versus pushing the rail cars. We found that UFP concentrations during bus, bicycling, and train commutes were 1.6-5.3 times greater than personal vehicle commutes, while light rail commutes had 30% lower UFP concentrations than personal vehicle commutes. The largest exposure per mile occurred during bicycle commutes with PM2.5, BC, and UFP exposures of 1.312 μg/mile, 0.097 μg/mile, and 3.0 × 109 particles/mile, respectively. Train commutes experienced the largest exposure per mile of all of the combustion-derived transportation commute modes. BC accounted for 5-20% of total PM mass across all commute modes with an average fraction of ∼7% of PM2.5.
Simplified equation for Young's modulus of CNT reinforced concrete
Chandran, RameshBabu; Gifty Honeyta A, Maria
2017-12-01
This research investigation focuses on finite element modeling of carbon nanotube (CNT) reinforced concrete matrix for three grades of concrete namely M40, M60 and M120. Representative volume element (RVE) was adopted and one-eighth model depicting the CNT reinforced concrete matrix was simulated using FEA software ANSYS17.2. Adopting random orientation of CNTs, with nine fibre volume fractions from 0.1% to 0.9%, finite element modeling simulations replicated exactly the CNT reinforced concrete matrix. Upon evaluations of the model, the longitudinal and transverse Young's modulus of elasticity of the CNT reinforced concrete was arrived. The graphical plots between various fibre volume fractions and the concrete grade revealed simplified equation for estimating the young's modulus. It also exploited the fact that the concrete grade does not have significant impact in CNT reinforced concrete matrix.
Multigene Genetic Programming for Estimation of Elastic Modulus of Concrete
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Alireza Mohammadi Bayazidi
2014-01-01
Full Text Available This paper presents a new multigene genetic programming (MGGP approach for estimation of elastic modulus of concrete. The MGGP technique models the elastic modulus behavior by integrating the capabilities of standard genetic programming and classical regression. The main aim is to derive precise relationships between the tangent elastic moduli of normal and high strength concrete and the corresponding compressive strength values. Another important contribution of this study is to develop a generalized prediction model for the elastic moduli of both normal and high strength concrete. Numerous concrete compressive strength test results are obtained from the literature to develop the models. A comprehensive comparative study is conducted to verify the performance of the models. The proposed models perform superior to the existing traditional models, as well as those derived using other powerful soft computing tools.
Young's Modulus of Single-Crystal Fullerene C Nanotubes
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Tokushi Kizuka
2012-01-01
Full Text Available We performed bending tests on single-crystal nanotubes composed of fullerene C70 molecules by in situ transmission electron microscopy with measurements of loading forces by an optical deflection method. The nanotubes with the outer diameters of 270–470 nm were bent using simple-beam and cantilever-beam loading by the piezomanipulation of silicon nanotips. Young's modulus of the nanotubes increased from 61 GPa to 110 GPa as the outer diameter decreased from 470 nm to 270 nm. Young's modulus was estimated to be 66% of that of single-crystal C60 nanotubes of the same outer diameter.
A Methodology for Determination of Resilient Modulus of Asphaltic Concrete
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A. Patel
2011-01-01
Full Text Available Resilient modulus, , is an important parameter for designing pavements. However, its determination by resorting to cyclic triaxial tests is tedious and time consuming. Moreover, empirical relationships, correlating to various other material properties (namely, California Bearing Ratio, CBR; Limerock Bearing Ratio, LBR; R-value and the Soil Support Value, SSV, give vast variation in the estimated results. With this in view, an electronic circuitry, which employs bender and extender elements (i.e., piezo-ceramic elements, was developed. Details of the circuitry and the testing methodology adopted for this purpose are presented in this paper. This methodology helps in determining the resilient modulus of the material quite precisely. Further, it is believed that this methodology would be quite useful to engineers and technologists for conducting quality check of the pavements, quite rapidly and easily.
Study on the Compressive Modulus of Nylon-11/Silica Nanocomposites
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Haseung Chung
2012-01-01
Full Text Available This paper investigates the unusual characteristics regarding the mechanical properties of Nylon-11 filled with different volume fractions of silica nanoparticles by selective laser sintering (SLS from numerical simulation. The compressive modulus was predicted by two different numerical models and compared with the experimentally measured one. While the two-phase model has a limited capability in explaining the unusual behavior shown in the compressive modulus obtained by experiments with 2% volume fraction of nanoparticles, the effective interface model can simulate the unexpected characteristic of nanocomposites according to the volume fraction of nanoparticles. We can conclude that the effective interface model should be employed to predict the mechanical properties of nanocomposites for efficiency and accuracy.
Influence of compression pressure on Young's modulus of ceramic samples
Al-Shantir, Omar; Trník, Anton
2017-07-01
The samples used in this study are created from a porcelain mixture. This mixture is a high strength aluminous porcelain which is used in electrotechnical engineering (high voltage insulators). The porcelain mixture contains clay, kaolin, feldspar, alumina, and small amount of other admixtures. The samples are made with three different compression pressures (80, 90, and 110 MPa). Impulse excitation technique, termodilatometry, and termogravimetry are used to determine Young's modulus. The analyses are performed in the temperature range from 30 °C to 1100 °C with a heating rate of 5 °C/min in a static air atmosphere. It is found out that values of Young's modulus do not increase linearly with the compression pressure.
Ultrasonic Measurement of Elastic Modulus of Kelvin Foam
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Oh Sukwon
2016-01-01
Full Text Available Elastic modulus of 3D-printed Kelvin foam plate is investigated by measuring the acoustic wave velocity of 1 MHz ultrasound. An isotropic tetrakaidecahedron foam of 3 mm unit cell is designed and printed layer upon layer to fablicate a Kelvin foam plate of 14mm thickness by 3D CAD/printer using ABS plastic. The Kelvin foam plate is filled completely with paraffin wax for impedance matching, so that acoustic wave may propagate through the porous foam plate. The acoustic wave velocity of the foam plate is measured using the time-of-flight (TOF method to calculate the elastic modulus of the Kelvin foam plate based on acousto-elasticity.
Biaxial flexural modulus of antibiotic-impregnated orthopedic bone cement.
Leone, James; Johnson, Amy; Ziada, Samir; Hashemi, Ata; Adili, Anthony; de Beer, Justin
2007-10-01
Previously reported antibiotic-impregnated cement strengths have been based on uniaxial and fatigue testing methodologies. These methods may not provide an accurate characterization of bone cement's true load-bearing capacity in total joint replacement (TJR). The present study utilized biaxial testing to report on the properties of antibiotic-impregnated cement. Test groups included: PMMA mixed with Vancomycin, Gentamicin, Tobramycin, or no antibiotic (control). In comparison to the control group, PMMA samples mixed with powdered gentamicin resulted in an increase in the mean elastic modulus by 6.50% versus a drop noted with powdered vancomycin and tobramycin by 2.65 and 1.37% respectively. The mean elastic modulus in samples containing liquid gentamicin dropped by 11.6%. This study supports the continued use of powdered antibiotics when clinically indicated, but suggest caution in the use of liquid gentamicin in TJR.
Frisch, Sophie; Glaz, Sarah; Tartarone, Francesca; Zanardo, Paolo
2017-01-01
This volume presents a collection of articles highlighting recent developments in commutative algebra and related non-commutative generalizations. It also includes an extensive bibliography and lists a substantial number of open problems that point to future directions of research in the represented subfields. The contributions cover areas in commutative algebra that have flourished in the last few decades and are not yet well represented in book form. Highlighted topics and research methods include Noetherian and non-Noetherian ring theory, module theory and integer-valued polynomials along with connections to algebraic number theory, algebraic geometry, topology and homological algebra. Most of the eighteen contributions are authored by attendees of the two conferences in commutative algebra that were held in the summer of 2016: “Recent Advances in Commutative Ring and Module Theory,” Bressanone, Italy; “Conference on Rings and Polynomials” Graz, Austria. There is also a small collection of invite...
Almasi, Gheorghe [Ardsley, NY; Blumrich, Matthias Augustin [Ridgefield, CT; Chen, Dong [Croton-On-Hudson, NY; Coteus, Paul [Yorktown, NY; Gara, Alan [Mount Kisco, NY; Giampapa, Mark E [Irvington, NY; Heidelberger, Philip [Cortlandt Manor, NY; Hoenicke, Dirk I [Ossining, NY; Singh, Sarabjeet [Mississauga, CA; Steinmacher-Burow, Burkhard D [Wernau, DE; Takken, Todd [Brewster, NY; Vranas, Pavlos [Bedford Hills, NY
2008-06-03
Methods and apparatus perform fault isolation in multiple node computing systems using commutative error detection values for--example, checksums--to identify and to isolate faulty nodes. When information associated with a reproducible portion of a computer program is injected into a network by a node, a commutative error detection value is calculated. At intervals, node fault detection apparatus associated with the multiple node computer system retrieve commutative error detection values associated with the node and stores them in memory. When the computer program is executed again by the multiple node computer system, new commutative error detection values are created and stored in memory. The node fault detection apparatus identifies faulty nodes by comparing commutative error detection values associated with reproducible portions of the application program generated by a particular node from different runs of the application program. Differences in values indicate a possible faulty node.
DEFF Research Database (Denmark)
Djurhuus, Sune; Hansen, Henning Sten; Aadahl, Mette
2014-01-01
or cycling to work or study each day and the distance to work or study. Data were obtained from the Danish National Health Survey collected in February to April 2010. Individual accessibility by public transportation was calculated using a multi-modal network in a GIS. Multilevel logistic regression was used...... individual public transportation accessibility and self-reported active commuting, and whether the associations varied with commute distance, age, and gender. METHODS: Twenty-eight thousand nine hundred twenty-eight commuters in The Capital Region of Denmark reported self-reported time spent either walking...... to analyze the association between accessibility, expressed as access area, and being an active commuter. RESULTS: Public transport accessibility area based on all stops within walking and cycling distance was positively associated with being an active commuter. Distance to work, age, and gender modified...
The commutation error of the space averaged Navier-Stokes equations on a bounded domain
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Dunca, A.; Layton, W.J. [Pittsburgh Univ., PA (United States). Dept. of Mathematics; John, V. [Magdeburg Univ. (Germany). Inst. fuer Analysis und Numerik
2002-01-01
In Large Eddy Simulation of turbulent flows, the Navier-Stokes equations are convolved with a filter and differentiation and convolution are interchanged, introducing an extra commutation error term, which is nearly universally dropped from the resulting equations. We show that the commutation error is asymptotically negligible in L{sup p}(R{sup d}) (i.e., it vanishes as the averaging radius {delta}{yields}0) if and only if the fluid and the boundary exert exactly zero force on each other. Next, we show that the commutation error tends to zero in H{sup -1}({omega}) as {delta}{yields}0. Convergence is proven also for a weak form of the commutation error. The order of convergence is studied in both cases. Last, we study the influence of the commutation error on the energy balance of the filtered equations. (orig.)
Alumina barrier for vacuum brazing
Beuyukian, C. S.
1980-01-01
Heating platens of vacuum-brazing press will not stick to workpiece if aluminum oxide "paper" is interposed. Paper does not disintegrate in press, will not contaminate braze alloy, and helps form smoothly contoured, regular fillet at brazed edges.
[Endoscopic vacuum-assisted closure].
Wedemeyer, J; Lankisch, T
2013-03-01
Anastomotic leakage in the upper and lower intestinal tract is associated with high morbidity and mortality. Within the last 10 years endoscopic treatment options have been accepted as sufficient treatment option of these surgical complications. Endoscopic vacuum assisted closure (E-VAC) is a new innovative endoscopic therapeutic option in this field. E-VAC transfers the positive effects of vacuum assisted closure (VAC) on infected cutaneous wounds to infected cavities that can only be reached endoscopically. A sponge connected to a drainage tube is endoscopically placed in the leakage and a continuous vacuum is applied. Sponge and vacuum allow removal of infected fluids and promote granulation of the leakage. This results in clean wound grounds and finally allows wound closure. Meanwhile the method was also successfully used in the treatment of necrotic pancreatitis.
SILICON REFINING BY VACUUM TREATMENT
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André Alexandrino Lotto
2014-12-01
Full Text Available This work aims to investigate the phosphorus removal by vacuum from metallurgical grade silicon (MGSi (98.5% to 99% Si. Melting experiments were carried out in a vacuum induction furnace, varying parameters such as temperature, time and relation area exposed to the vacuum / volume of molten silicon. The results of chemical analysis were obtained by inductively coupled plasma (ICP, and evaluated based on thermodynamic and kinetic aspects of the reaction of vaporization of the phosphorus in the silicon. The phosphorus was decreased from 33 to approximately 1.5 ppm after three hours of vacuum treatment, concluding that the evaporation step is the controlling step of the process for parameters of temperature, pressure and agitation used and refining by this process is technically feasible.
Young's modulus of elasticity of Schlemm's canal endothelial cells.
Zeng, Dehong; Juzkiw, Taras; Read, A Thomas; Chan, Darren W-H; Glucksberg, Matthew R; Ethier, C Ross; Johnson, Mark
2010-02-01
Schlemm's canal (SC) endothelial cells are likely important in the physiology and pathophysiology of the aqueous drainage system of the eye, particularly in glaucoma. The mechanical stiffness of these cells determines, in part, the extent to which they can support a pressure gradient and thus can be used to place limits on the flow resistance that this layer can generate in the eye. However, little is known about the biomechanical properties of SC endothelial cells. Our goal in this study was to estimate the effective Young's modulus of elasticity of normal SC cells. To do so, we combined magnetic pulling cytometry of isolated cultured human SC cells with finite element modeling of the mechanical response of the cell to traction forces applied by adherent beads. Preliminary work showed that the immersion angles of beads attached to the SC cells had a major influence on bead response; therefore, we also measured bead immersion angle by confocal microscopy, using an empirical technique to correct for axial distortion of the confocal images. Our results showed that the upper bound for the effective Young's modulus of elasticity of the cultured SC cells examined in this study, in central, non-nuclear regions, ranged between 1,007 and 3,053 Pa, which is similar to, although somewhat larger than values that have been measured for other endothelial cell types. We compared these values to estimates of the modulus of primate SC cells in vivo, based on images of these cells under pressure loading, and found good agreement at low intraocular pressure (8-15 mm Hg). However, increasing intraocular pressure (22-30 mm Hg) appeared to cause a significant increase in the modulus of these cells. These moduli can be used to estimate the extent to which SC cells deform in response to the pressure drop across the inner wall endothelium and thereby estimate the extent to which they can generate outflow resistance.
Isentropic Bulk Modulus: Development of a Federal Test Method
2016-01-01
bulk modulus space from synthetic iso -paraffinic fuels to petroleum-based diesel fuels. The test fuels are identified in Table 1. A testing order and...13000 100 14000 100 15000 100 UNCLASSIFIED UNCLASSIFIED 7 3.3 ROUND ROBIN PROCEDURE The following notes were provided to the participating...2 Table A-1. Sample 6065 at 35 °C Density psi 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000 15000 Avg g/cm3
Modulus Dependence on Large Scale Porosity of Powder Metallurgy Steel
Allison, P. G.; Horstemeyer, M. F.; Brown, H. R.
2012-07-01
This article compares the existing theoretical expressions for the porosity dependence on elastic constants to experimental data for a commercially available material, FC-0205 powder metallurgy (PM) steel. The modulus of compression, tension, effective torsion, and ultrasound-based data at varying porosity levels are plotted graphically against the theoretical expressions. An equation by McAdam ( J. Iron Steel Inst. Lond., 1950, 168, p 346) was able to most accurately predict the experimental data with the adjustment of only one material constant.
Vacuum production; Produccion de vacio
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Segovia, J. L. de
2010-07-01
Since the advent of ultra high vacuum in 1958 has been a great demand for new as means of production and to meet the process needs to be done: industry heavy, high technology and space research areas, large accelerator systems particles or nuclear fusion. In this paper we explore the modern media production: dry vacuum pumps, turbo pumps, pump status diffusion ion pumps and cryopumps. (Author)
Measurement of the elasticity modulus of soft tissues.
Zörner, S; Kaltenbacher, M; Lerch, R; Sutor, A; Döllinger, M
2010-05-28
A measurement setup combined with a Finite Element (FE) simulation is presented to determine the elasticity modulus of soft materials as a function of frequency. The longterm goal of this work is to measure in vitro the elasticity modulus of human vocal folds over a frequency range that coincides with the range of human phonation. The results will assist numerical simulations modeling the phonation process by providing correct material parameters. Furthermore, the measurements are locally applied, enabling to determine spatial differences along the surface of the material. In this work the method will be presented and validated by applying it to silicones with similar characteristics as human vocal folds. Three silicone samples with different consistency were tested over a frequency range of 20-250 Hz. The results of the pipette aspiration method revealed a strong frequency dependency of the elasticity modulus, especially below 100 Hz. In this frequency range the elasticity moduli of the samples varied between 5 and 27 kPa. Copyright 2010 Elsevier Ltd. All rights reserved.
Determination of the flexural modulus of elasticity of orthodontic archwires.
Tian, Kun; Darvell, Brian W
2010-08-01
To design a protocol for the determination of the flexural modulus of elasticity of wire with high accuracy and precision. Cantilever bending was used at long span and low loads, using a laser displacement sensor. Various wires were tested for proof-of-concept: stainless steel, Elgiloy, Wiptam and a gold alloy, with primary attention being paid to the source and magnitude of errors. The moduli of elasticity were determined with a median relative error of approximately 0.15%, with a worst case of 0.56%, taking into account all measurement errors. The precision was such as to permit distinctions between the values for the wires of different thermomechanical history. The determination of the elastic modulus of wires may be made with good precision using cantilever bending providing attention is given to all sources of error. These results represent the most reliable measures of modulus of elasticity of orthodontic archwires to date. Copyright 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
Elastohydrodynamics of elliptical contacts for materials of low elastic modulus
Hamrock, B. J.; Dowson, D.
1983-01-01
The influence of the ellipticity parameter k and the dimensionless speed U, load W, and materials G parameters on minimum film thickness for materials of low elastic modulus was investigated. The ellipticity parameter was varied from 1 (a ball-on-plane configuration) to 12 (a configuration approaching a line contact); U and W were each varied by one order of magnitude. Seventeen cases were used to generate the minimum- and central-film-thickness relations. The influence of lubricant starvation on minimum film thickness in starved elliptical, elastohydrodynamic configurations was also investigated for materials of low elastic modulus. Lubricant starvation was studied simply by moving the inlet boundary closer to the center of the conjunction in the numerical solutions. Contour plots of pressure and film thickness in and around the contact were presented for both fully flooded and starved lubrication conditions. It is evident from these figures that the inlet pressure contours become less circular and closer to the edge of the Hertzian contact zone and that the film thickness decreases substantially as the serverity of starvation increases. The results presented reveal the essential features of both fully flooded and starved, elliptical, elastohydrodynamic conjunctions for materials of low elastic modulus.
Elastic modulus of tree frog adhesive toe pads.
Barnes, W Jon P; Goodwyn, Pablo J Perez; Nokhbatolfoghahai, Mohsen; Gorb, Stanislav N
2011-10-01
Previous work using an atomic force microscope in nanoindenter mode indicated that the outer, 10- to 15-μm thick, keratinised layer of tree frog toe pads has a modulus of elasticity equivalent to silicone rubber (5-15 MPa) (Scholz et al. 2009), but gave no information on the physical properties of deeper structures. In this study, micro-indentation is used to measure the stiffness of whole toe pads of the tree frog, Litoria caerulea. We show here that tree frog toe pads are amongst the softest of biological structures (effective elastic modulus 4-25 kPa), and that they exhibit a gradient of stiffness, being stiffest on the outside. This stiffness gradient results from the presence of a dense network of capillaries lying beneath the pad epidermis, which probably has a shock absorbing function. Additionally, we compare the physical properties (elastic modulus, work of adhesion, pull-off force) of the toe pads of immature and adult frogs.
Pengukuran Modulus Elastisitas Dinamis Batuan dengan Metode Seismik Refraksi
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Ashadi Salim
2012-12-01
Full Text Available The seismic wave velocity in rock formation depends on the elastic modulus and mass density of rock where the wave travels. The velocity measurement of P and S waves on rock formation and the mass density in the laboratory can be used for calculating the elastic modulus of rock formation. The elastic modulus is part of rock mechanical parameter needed in geological engineering researches. The velocity measurement of P and S waves by the seismic refraction method was done on a tunnel with 11 spreads of measurement. From the resultsof the measurement, three groups of rock formation could be identified. The first is rock formation with Ed=8.890-12.68 MPa and G=3.306-4.830MPa; the second group is rock formation with Ed=8.890-12.68 MPa and G=3.306-4.830MPa; and the third group is with Ed=18.520-21.120MPa and G=6.724-7.744MP. The first group is clay formation while the second and third groups are andesitic stone formation.
Ancestrally high elastic modulus of gecko setal beta-keratin.
Peattie, Anne M; Majidi, Carmel; Corder, Andrew; Full, Robert J
2007-12-22
Typical bulk adhesives are characterized by soft, tacky materials with elastic moduli well below 1MPa. Geckos possess subdigital adhesives composed mostly of beta-keratin, a relatively stiff material. Biological adhesives like those of geckos have inspired empirical and modelling research which predicts that even stiff materials can be effective adhesives if they take on a fibrillar form. The molecular structure of beta-keratin is highly conserved across birds and reptiles, suggesting that material properties of gecko setae should be similar to that of beta-keratin previously measured in birds, but this has yet to be established. We used a resonance technique to measure elastic bending modulus in two species of gecko from disparate habitats. We found no significant difference in elastic modulus between Gekko gecko (1.6 GPa +/- 0.15s.e.; n=24 setae) and Ptyodactylus hasselquistii (1.4 GPa +/- 0.15s.e.; n=24 setae). If the elastic modulus of setal keratin is conserved across species, it would suggest a design constraint that must be compensated for structurally, and possibly explain the remarkable variation in gecko adhesive morphology.
Compressive elastic modulus of natural fiber based binary composites
Widayani, Susanah, Y.; Utami, L. S.; Khotimah, S. N.; Viridi, S.
2012-06-01
The composites made of bamboo apus fiber - epoxy resin and charcoal - tapioca starch with several compositions have been synthesized. Bamboo fiber powder as the rest of cutting process was refined and filtered by mesh 40 before used. Epoxy resin 1021A and hardener 1021B has been used as resin. The synthesis of epoxy resin-based composites was carried out via simple mixing method by adding adequate 70% ethanol solution before drying. The 100 mesh-filtered dry charcoal was mixed with tapioca mixture before it was pressed and dried to produce briquette composites. To study the compressive elastic modulus of the composites, pressure tests using Mark 10 Pressure Test Machine have been carried out. It was found that all the composites show maximum compressive elastic modulus at certain component compositions. The maximum elastic modulus for bamboo fiber-epoxy resin, charcoal - epoxy resin and charcoal-tapioca starch were observed at 52.9%, 56.3%, and 25.0% of mass fraction of bamboo fiber, charcoal and tapioca starch, respectively.
Measuring the elastic modulus of ex vivo small tissue samples.
Samani, Abbas; Bishop, Jonathan; Luginbuhl, Chris; Plewes, Donald B
2003-07-21
Over the past decade, several methods have been proposed to image tissue elasticity based on imaging methods collectively called elastography. While progress in developing these systems has been rapid, the basic understanding of tissue properties to interpret elastography images is generally lacking. To address this limitation, we developed a system to measure the Young's modulus of small soft tissue specimens. This system was designed to accommodate biological soft tissue constraints such as sample size, geometry imperfection and heterogeneity. The measurement technique consists of indenting an unconfined small block of tissue while measuring the resulting force. We show that the measured force-displacement slope of such a geometry can be transformed to the tissue Young's modulus via a conversion factor related to the sample's geometry and boundary conditions using finite element analysis. We also demonstrate another measurement technique for tissue elasticity based on quasi-static magnetic resonance elastography in which a tissue specimen encased in a gelatine-agarose block undergoes cyclical compression with resulting displacements measured using a phase contrast MRI technique. The tissue Young's modulus is then reconstructed from the measured displacements using an inversion technique. Finally, preliminary elasticity measurement results of various breast tissues are presented and discussed.
Production of a low young modulus titanium alloy by powder metallurgy
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Dalcy Roberto dos Santos
2005-12-01
Full Text Available Titanium alloys have several advantages over ferrous and non-ferrous metallic materials, such as high strengthto-weight ratio and excellent corrosion resistance. A blended elemental titanium powder metallurgy process has been developed to offer low cost commercial products. The process employs hydride-dehydride (HDH powders as raw material. In this work, results of the Ti-35Nb alloy sintering are presented. This alloy due to its lower modulus of elasticity and high biocompatibility is a promising candidate for aerospace and medical use. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by isochronal sintering between 900 up to 1600 °C, in vacuum. Sintering behavior was studied by means of microscopy and density. Sintered samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively. Samples sintered at high temperatures display a fine plate-like alpha structure and intergranular beta. A few remaining pores are still found and density above 90% for specimens sintered in temperatures over 1500 °C is reached.
Guell, C.; Panter, J.; Jones, N.R.; Ogilvie, D.
2012-01-01
Fostering physical activity is an established public health priority for the primary prevention of a variety of chronic diseases. One promising population approach is to seek to embed physical activity in everyday lives by promoting walking and cycling to and from work (‘active commuting’) as an alternative to driving. Predominantly quantitative epidemiological studies have investigated travel behaviours, their determinants and how they may be changed towards more active choices. This study aimed to depart from narrow behavioural approaches to travel and investigate the social context of commuting with qualitative social research methods. Within a social practice theory framework, we explored how people describe their commuting experiences and make commuting decisions, and how travel behaviour is embedded in and shaped by commuters' complex social worlds. Forty-nine semi-structured interviews and eighteen photo-elicitation interviews with accompanying field notes were conducted with a subset of the Commuting and Health in Cambridge study cohort, based in the UK. The findings are discussed in terms of three particularly pertinent facets of the commuting experience. Firstly, choice and decisions are shaped by the constantly changing and fluid nature of commuters' social worlds. Secondly, participants express ambiguities in relation to their reasoning, ambitions and identities as commuters. Finally, commuting needs to be understood as an embodied and emotional practice. With this in mind, we suggest that everyday decision-making in commuting requires the tactical negotiation of these complexities. This study can help to explain the limitations of more quantitative and static models and frameworks in predicting travel behaviour and identify future research directions. PMID:22486840
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Li Ping Wong
2017-09-01
Full Text Available This research aimed to investigate the control measures used by public transport commuters and their health (physical and psychological effects due to exposure to air pollution during their daily commute and during haze days. From June to October 2016, 800 public transport commuters in urban cities in the heart of Selangor, Malaysia were interviewed. Of these, 25.4% reported sometimes/often wearing surgical masks during their daily commute, while 92.1% reported such use during haze days. The total control measure score against air pollutants during the daily commute was low; on a control measure scale of 0–18, the median rating during the daily commute was 8 (interquartile range (IQR 6–10. During haze days, control measures improved slightly (median 14, IQR 12–16. Evidence of adverse health effects was present. During the daily commute under normal conditions, the three highest adverse health experiences were fatigue and weakness (35.5%, coughing (23.6%, and dizziness (18.2%. During haze days, the three highest adverse health experiences were headache (85%, coughing (84.8%, and breathing difficulties (84.5%. On a possible total adverse health (physical and psychological experience scale of 0–22, the median rating during the daily commute was 1 (IQR 0–3. The median rating during haze days was intensified (median 11, IQR 9–13. Public transportation commuters should be encouraged to enhance various control measures against particulate air pollutants during their daily commute, particularly during haze days, to minimize the adverse health risks associated with air pollutants.
Edge conduction in vacuum glazing
Energy Technology Data Exchange (ETDEWEB)
Simko, T.M.; Collins, R.E. [Sydney Univ., NSW (Australia). Dept. of Applied Physics; Beck, F.A.; Arasteh, D. [Lawrence Berkeley Lab., CA (United States)
1995-03-01
Vacuum glazing is a form of low-conductance double glazing using in internal vacuum between the two glass sheets to eliminate heat transport by gas conduction and convection. An array of small support pillars separates the sheets; fused solder glass forms the edge seal. Heat transfer through the glazing occurs by radiation across the vacuum gap, conduction through the support pillars, and conduction through the bonded edge seal. Edge conduction is problematic because it affects stresses in the edge region, leading to possible failure of the glazing; in addition, excessive heat transfer because of thermal bridging in the edge region can lower overall window thermal performance and decrease resistance to condensation. Infrared thermography was used to analyze the thermal performance of prototype vacuum glazings, and, for comparison, atmospheric pressure superwindows. Research focused on mitigating the edge effects of vacuum glazings through the use of insulating trim, recessed edges, and framing materials. Experimentally validated finite-element and finite-difference modeling tools were used for thermal analysis of prototype vacuum glazing units and complete windows. Experimental measurements of edge conduction using infrared imaging were found to be in good agreement with finite-element modeling results for a given set of conditions. Finite-element modeling validates an analytic model developed for edge conduction.
Vacuum-assisted cesarean section
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McQuivey RW
2017-03-01
Full Text Available Ross W McQuivey,1 Jon E Block2 1Clinical Innovations, Salt Lake City, UT, 2Independent consultant, San Francisco, CA, USA Abstract: There has been a dramatic rise in the frequency of cesarean sections, surpassing 30% of all deliveries in the US. This upsurge, coupled with a decreasing willingness to allow vaginal birth after cesarean section, has resulted in an expansion of the use of vacuum assistance to safely extract the fetal head. By avoiding the use of a delivering hand or forceps blade, the volume being delivered through the uterine incision can be decreased when the vacuum is used properly. Reducing uterine extensions with their associated complications (eg, excessive blood loss in difficult cases is also a theoretical advantage of vacuum delivery. Maternal discomfort related to excessive fundal pressure may also be lessened. To minimize the risk of neonatal morbidity, proper cup placement over the “flexion point” remains essential to maintain vacuum integrity and reduce the chance of inadvertent detachment and uterine extensions. Based on the published literature and pragmatic clinical experience, utilization of the vacuum device is a safe and effective technique to assist delivery during cesarean section. Keywords: cesarean section, vacuum, forceps, birth, delivery
Technical specification for vacuum systems
Energy Technology Data Exchange (ETDEWEB)
Khaw, J. (ed.)
1987-01-01
The vacuum systems at the Stanford Linear Accelerator Center (SLAC) are primarily of all-metal construction and operate at pressures from 10/sup -5/ to 10/sup -11/ Torr. The primary gas loads during operation result from thermal desorption and beam-induced desorption from the vacuum chamber walls. These desorption rates can be extremely high in the case of hydrocarbons and other contaminants. These specifications place a major emphasis on eliminating contamination sources. The specifications and procedures have been written to insure the cleanliness and vacuum integrity of all SLAC vacuum systems, and to assist personnel involved with SLAC vacuum systems in choosing and designing components that are compatible with existing systems and meet the quality and reliability of SLAC vacuum standards. The specification includes requirements on design, procurement, fabrication, chemical cleaning, clean room practices, welding and brazing, helium leak testing, residual gas analyzer testing, bakeout, venting, and pumpdown. Also appended are specifications regarding acceptable vendors, isopropyl alcohol, bakeable valve cleaning procedure, mechanical engineering safety inspection, notes on synchrotron radiation, and specifications of numerous individual components. (LEW)
Nie, Li; Zhan, Yongzhong; Hu, Tong; Chen, Xiaoxian; Wang, Chenghui
2014-01-01
In order to develop new biomedical materials for hard tissue replacements, Zr-20Nb-xTi (x=0, 3, 7, 11 and 15) alloys with required properties were designed and prepared by using the vacuum arc melting method for the first time. Phase analysis and microstructural observation showed that all the as cast samples consisted of equiaxed β-Zr phase. The mechanical properties and fracture behaviors of the Zr-20Nb-xTi alloys have been analyzed. It is found that these alloys exhibit high plasticity, moderate compressive strength (1044-1325MPa) and yield stress (854-1080MPa), high elastic energy (12-20MJ/m(3)) and low Young's modulus (28-31GPa). This good combination of mechanical properties makes them potential biomedical materials for hard tissue replacement. © 2013 Elsevier Ltd. All rights reserved.
The relationship between bicycle commuting and perceived stress: a cross-sectional study
Avila-Palencia, Ione; de Nazelle, Audrey; Cole-Hunter, Tom; Donaire-Gonzalez, David; Jerrett, Michael; Rodriguez, Daniel A; Nieuwenhuijsen, Mark J
2017-01-01
Introduction Active commuting — walking and bicycling for travel to and/or from work or educational addresses — may facilitate daily, routine physical activity. Several studies have investigated the relationship between active commuting and commuting stress; however, there are no studies examining the relationship between solely bicycle commuting and perceived stress, or studies that account for environmental determinants of bicycle commuting and stress. The current study evaluated the relationship between bicycle commuting, among working or studying adults in a dense urban setting, and perceived stress. Methods A cross-sectional study was performed with 788 adults who regularly travelled to work or study locations (excluding those who only commuted on foot) in Barcelona, Spain. Participants responded to a comprehensive telephone survey concerning their travel behaviour from June 2011 through to May 2012. Participants were categorised as either bicycle commuters or non-bicycle commuters, and (based on the Perceived Stress Scale, PSS-4) as either stressed or non-stressed. Multivariate Poisson regression with robust variance models of stress status based on exposures with bicycle commuting were estimated and adjusted for potential confounders. Results Bicycle commuters had significantly lower risk of being stressed than non-bicycle commuters (Relative Risk; RR (95% CI)=0.73 (0.60 to 0.89), p=0.001). Bicycle commuters who bicycled 4 days per week (RR (95% CI)=0.42 (0.24 to 0.73), p=0.002) and those who bicycled 5 or more days per week (RR (95% CI)=0.57 (0.42 to 0.77), pstressed than those who bicycled less than 4 days. This relationship remained statistically significant after adjusting for individual and environmental confounders and when using different cut-offs of perceived stress. Conclusions Stress reduction may be an important consequence of routine bicycle use and should be considered by decision makers as another potential benefit of its
Criterion distances and environmental correlates of active commuting to school in children
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D'Haese Sara
2011-08-01
Full Text Available Abstract Background Active commuting to school can contribute to daily physical activity levels in children. Insight into the determinants of active commuting is needed, to promote such behavior in children living within a feasible commuting distance from school. This study determined feasible distances for walking and cycling to school (criterion distances in 11- to 12-year-old Belgian children. For children living within these criterion distances from school, the correlation between parental perceptions of the environment, the number of motorized vehicles per family and the commuting mode (active/passive to school was investigated. Methods Parents (n = 696 were contacted through 44 randomly selected classes of the final year (sixth grade in elementary schools in East- and West-Flanders. Parental environmental perceptions were obtained using the parent version of Neighborhood Environment Walkability Scale for Youth (NEWS-Y. Information about active commuting to school was obtained using a self-reported questionnaire for parents. Distances from the children's home to school were objectively measured with Routenet online route planner. Criterion distances were set at the distance in which at least 85% of the active commuters lived. After the determination of these criterion distances, multilevel analyses were conducted to determine correlates of active commuting to school within these distances. Results Almost sixty percent (59.3% of the total sample commuted actively to school. Criterion distances were set at 1.5 kilometers for walking and 3.0 kilometers for cycling. In the range of 2.01 - 2.50 kilometers household distance from school, the number of passive commuters exceeded the number of active commuters. For children who were living less than 3.0 kilometers away from school, only perceived accessibility by the parents was positively associated with active commuting to school. Within the group of active commuters, a longer distance to school
The effects of commuter pedestrian traffic on the use of stairs in an urban setting.
Andersen, Ross E; Bauman, Adrian E
2011-01-01
Most public health physical activity guidelines now encourage people to look for opportunities to accumulate physical activity throughout the day. Climbing stairs in lieu of riding escalators is a prime opportunity to make healthier choices that promote active living. The purpose of this investigation was to examine the effects of pedestrian commuter traffic on choices to ride an escalator, walk up an escalator, or walk up adjacent stairs in a busy urban subway station at rush hour. A total of 9766 commuters were observed by two recorders for a 2.5-hour period during the morning rush hour over 8 weeks as to whether the commuters walked up stairs or rode an adjacent escalator in a subway station. The number of observations per 5-minute block was recorded, and an index of commuter traffic was computed. Demographic information and use of escalators/stairs were also recorded. An urban subway station with a two-flight staircase adjacent to an escalator. Adult commuters travelling to work during the morning rush hour. Physical activity choices were examined in relation to commuter traffic. Demographic information, such as age, race, and weight status, were also considered. A χ(2) analysis was used to examine differences in proportions across variables of interest. Means were compared by using multivariate analysis of variance, and confidence intervals were computed. During the least-heavy commuter traffic period, only 11.2% of commuters chose to walk up the stairs, whereas significantly more did so during moderate 18.7% and high 20.8% commuter traffic periods (χ(2) = 61.8, p < .001). During low-traffic times, significantly more commuters (21.4%) walked up the escalators compared with moderate-traffic (18.0%) or high-traffic (18.3%) periods. African-American commuters passively rode the escalator more (68.2%) than white commuters (56.7%), and their patterns were less affected by commuter traffic (p < .05). Congestion in public places can have a significant effect
Dirac oscillator in a Galilean covariant non-commutative space
Energy Technology Data Exchange (ETDEWEB)
Melo, G.R. de [Universidade Federal do Reconcavo da Bahia, BA (Brazil); Montigny, M. [University of Alberta (Canada); Pompeia, P.J. [Instituto de Fomento e Coordecacao Industrial, Sao Jose dos Campos, SP (Brazil); Santos, Esdras S. [Universidade Federal da Bahia, Salvador (Brazil)
2013-07-01
Full text: Even though Galilean kinematics is only an approximation of the relativistic kinematics, the structure of Galilean kinematics is more intricate than relativistic kinematics. For instance, the Galilean algebra admits a nontrivial central extension and projective representations, whereas the Poincare algebra does not. It is possible to construct representations of the Galilei algebra with three possible methods: (1) directly from the Galilei algebra, (2) from contractions of the Poincare algebra with the same space-time dimension, or (3) from the Poincare algebra in a space-time with one additional dimension. In this paper, we follow the third approach, which we refer to as 'Galilean covariance' because the equations are Lorentz covariant in the extended manifold. These equations become Galilean invariant after projection to the lower dimension. Our motivation is that this covariant approach provides one more unifying feature of field theory models. Indeed, particle physics (with Poincare kinematics) and condensed matter physics (with Galilean kinematics) share many tools of quantum field theory (e.g. gauge invariance, spontaneous symmetry breaking, Goldstone bosons), but the Galilean kinematics does not admit a metric structure. However, since the Galilean Lie algebra is a subalgebra of the Poincare Lie algebra if one more space-like dimension is added, we can achieve 'Galilean covariance' with a metric in an extended manifold; that makes non-relativistic models look similar to Lorentz-covariant relativistic models. In this context we study the Galilei covariant five-dimensional formulation applied to Galilean Dirac oscillator in a non-commutative situation, with space-space and momentum-momentum non-commutativity. The wave equation is obtained via a 'Galilean covariant' approach, which consists in projecting the covariant motion equations from a (4, l)-dimensional manifold with light-cone coordinates, to a (3, l
Determination of resilient modulus values for typical plastic soils in Wisconsin.
2011-09-01
"The objectives of this research are to establish a resilient modulus test results database and to develop : correlations for estimating the resilient modulus of Wisconsin fine-grained soils from basic soil properties. A : laboratory testing program ...
Evaluation of Variability in Resilient Modulus Test Results (ASTM D4123)
1989-10-01
Samples of asphalt mixture were evaluated in the laboratory under various conditions to evaluate the repeatability of the resilient modulus test and to evaluate the effect of stress on the measured resilient modulus. Some of the samples were prepared...
Gömze, L. A.; Gömze, L. N.
2017-02-01
Materials with different crystalline and morphological compositions have different chemical, physical, mechanical and rheological properties, including wear protection, melting temperature, module of elasticity and viscosity. Examining the material structures and behaviors of differentceramic bodies and CMCs under high speed collisions in several years the authors have understood the advantages of hetero-modulus and hetero-viscous complex material systems to absorb and dissipate the kinetic energy of objects during high speed collisions. Applying the rheo-mechanical principles the authors successfully developed a new family of hetero-modulus and hetero-viscous alumina matrix composite materials with extreme mechanical properties including dynamic strength. These new corundum-matrix composite materials reinforced with Si2ON 2, Si3N4 , SiAlON and AlN submicron and nanoparticles have excellent dynamic strength during collisions with high density metallic bodies with speeds about 1000 m/sec or more. At the same time in the alumina matrix composites can be observed a phase transformation of submicron and nanoparticles of alpha and beta silicone-nitride crystals into cubicc-Si3N4 diamond-like particles can be observed, when the high speed collision processes are taken place in vacuum or oxygen-free atmosphere. Using the rheological principles and the energy engorgement by fractures, heating and melting of components the authors successfully developed several new hetero-modulus, hetero-viscous and hetero-plastic complex materials. These materials generally are based on ceramic matrixes and components having different melting temperatures and modules of elasticity from low values like carbon and light metals (Mg, Al, Ti, Si) up to very high values like boride, nitride and carbide ceramics. Analytical methods applied in this research were scanning electron microscopy, X-ray diffractions and energy dispersive spectrometry. Digital image analysis was applied to microscopy
Baryon number violation and novel canonical anti-commutation relations
Fujikawa, Kazuo; Tureanu, Anca
2018-02-01
The possible neutron-antineutron oscillation is described by an effective quadratic Lagrangian analogous to the BCS theory. It is shown that the conventional equal-time anti-commutation relations of the neutron variable n (t , x →) are modified by the baryon number violating terms. This is established by the Bjorken-Johnson-Low prescription and also by the canonical quantization combined with equations of motion. This novel canonical behavior can give rise to an important physical effect, which is illustrated by analyzing the Lagrangian that violates the baryon number but gives rise to the degenerate effective Majorana fermions and thus no neutron-antineutron oscillation. Technically, this model is neatly treated using a relativistic analogue of the Bogoliubov transformation.
Commutative deformations of general relativity: nonlocality, causality, and dark matter
Energy Technology Data Exchange (ETDEWEB)
De Vegvar, P.G.N. [SWK Research, Bellingham, WA (United States)
2017-01-15
Hopf algebra methods are applied to study Drinfeld twists of (3+1)-diffeomorphisms and deformed general relativity on commutative manifolds. A classical nonlocality length scale is produced above which microcausality emerges. Matter fields are utilized to generate self-consistent Abelian Drinfeld twists in a background independent manner and their continuous and discrete symmetries are examined. There is negligible experimental effect on the standard model of particles. While baryonic twist producing matter would begin to behave acausally for rest masses above ∝1-10 TeV, other possibilities are viable dark matter candidates or a right-handed neutrino. First order deformed Maxwell equations are derived and yield immeasurably small cosmological dispersion and produce a propagation horizon only for photons at or above Planck energies. This model incorporates dark matter without any appeal to extra dimensions, supersymmetry, strings, grand unified theories, mirror worlds, or modifications of Newtonian dynamics. (orig.)
The Higgs Mechanism in Non-commutative Gauge Theories
Energy Technology Data Exchange (ETDEWEB)
Petriello, Frank J
2001-01-17
This paper investigates the non-commutative version of the Abelian Higgs model at the one loop level. We find that the BRST invariance of the theory is maintained at this order in perturbation theory, rendering the theory one-loop renormalizable. Upon removing the gauge field from the theory we also obtain a consistent continuum renormalization of the broken O(2) linear sigma model, contradicting results found in the literature. The beta functions for the various couplings of the gauged U(1) theory are presented, as are the divergent contributions to every one particle irreducible (1PI) function. We find that all physical couplings and masses are gauge independent. A brief discussion concerning the symmetries P, C, and T in this theory is also given.
The Return of Organisation Man: Commuter Narratives and Suburban Critique
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Melissa Gregg
2012-09-01
Full Text Available This article considers the significance of suburban commuter imagery in a selection of screen visions of mid-century modernity. A number of examples, including Mad Men, and the screen adaptations of The Man in the Grey Flannel Suit (1956 and Revolutionary Road (2008, will be shown to echo key themes, symbols and scenes in their depictions of suburbia and the cultural impact of the corporation. Taken together, these narratives indicate the resilience of the “Organization Man” (Whyte 1956 as a figure marking the tension between individualism and conformity. It is this tension that the archetypal businessman’s uniform continues to symbolise in popular culture, even if, as this paper will argue, it is no longer the most fitting expression available.
Geodesics in hypercomplex number systems. Application to commutative quaternions
Energy Technology Data Exchange (ETDEWEB)
Catoni, Francesco; Zampetti, Paolo [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Energia; Cannata, Roberto [ENEA, Centro Ricerche Casaccia, Rome (Italy). Funzione Centrale INFO; Bordoni, Luciana [ENEA, Centro Ricerche Casaccia, Rome (Italy). Funzione Centrale Studi
1997-10-01
The functions of hypercomplex variable can be related to the physical fields. Following the Einstein`s ideas, by which the Theory of General Relativity was developed, they want to verify if a generalisation is possible, in order to described the motion of a body in a gravitational field, by the geodesics in spaces ``deformed`` by functional transformations of hypercomplex variables. These number systems introduce new space symmetries. This paper is just a first step in the more extended study. As a first application they consider the ``commutative quaternions`` system that may be considered as a composition of complex and hyperbolic numbers. By using in this system the same functional transformations valid for the two dimensional case, elliptical geodesics are obtained, with the eccentricity related to the angle between the orbit plane and a reference plane. These geodesics do not describe the Kepler orbits, but they show a space anisotropy that might be related to planet orbits of the solar system.
Directory of Open Access Journals (Sweden)
Erik Stigell
2015-12-01
Full Text Available Active commuting between home and place of work or study is often cited as an interesting source of physical activity in a public health perspective. However, knowledge about these behaviors is meager. This was therefore studied in adult active commuters (n = 1872 in Greater Stockholm, Sweden, a Nordic metropolitan setting. They received questionnaires and individually adjusted maps to draw their normal commuting route. Three different modality groups were identified in men and women: single-mode cyclists and pedestrians (those who only cycle or walk, respectively and dual-mode commuters (those who alternately walk or cycle. Some gender differences were observed in trip distances, frequencies, and velocities. A large majority of the commuting trip durations met the minimum health recommendation of at least 10-minute-long activity bouts. The median single-mode pedestrians and dual-mode commuters met or were close to the recommended weekly physical activity levels of at least 150 minutes most of the year, whereas the single-mode cyclists did so only during spring–mid-fall. A high total number of trips per year (range of medians: 230–390 adds to the value in a health perspective. To fully grasp active commuting behaviors in future studies, both walking and cycling should be assessed over different seasons and ideally over the whole year.
Is the environment near school associated with active commuting to school among preschoolers?
Directory of Open Access Journals (Sweden)
Jose Cazuza Farias Junior
2013-05-01
Full Text Available Available studies show that environmental factors may influence how parentes choose to commute their children from home to school. Thus, the aim of this study was to analyze the association between the characteristics of the physical and social environment near school and active commuting to school among preschool children. A school-based cross-sectional study with a sample of children aged 3to 5 years (n=914 was undertaken. Participants were selected by a single-stage cluster sampling process. To obtain data on commuting to school and demographicand socioeconomic variables, a previously validated questionnaire was used while an audit tool was used to assess the environment near school. Binarylogistic regression was used to analyze the association and results were presented as Odds Ratio values. Results showed that 28.3% (95%CI 25.5-31.3 ofthe children were active commuters from home to school. A positive association was found between public transportation (p=0.002 and social environment(p=0.004 domains and active commuting. However, this association was foundonly among children from families that did not have a car. The likelihood of achild being an active commuter was higher among those who are enrolled in schools with better environmental surroundings (OR=1.88; 95%CI 1.31-2.70. It was concluded that there was a positive association between some of the environmental factors near school and active commuting to school among children from families that did not have a car.
Active commuting and perceptions of the route environment: a longitudinal analysis.
Panter, Jenna; Griffin, Simon; Ogilvie, David
2014-10-01
To assess associations between changes in perceptions of the environment en route to work and changes in active commuting. 655 commuters in Cambridge, UK reported perceptions of their commuting route and past-week commuting trips in postal questionnaires in 2009 and 2010. Associations between changes in route perceptions and changes in time spent walking and cycling, proportion of car trips, and switching to or from the car on the commute were modelled using multivariable regression. Changes in only a few perceptions were associated with changes in travel behaviour. Commuters who reported that it became less pleasant to walk recorded a 6% (95% CI: 1, 11) net increase in car trips and a 12 min/week (95% CI: -1, -24) net decrease in walking. Increases in the perceived danger of cycling or of crossing the road were also associated with increases in car trips. Increases in the perceived convenience of public transport (OR: 3.31, 95% CI: 1.27, 8.63) or safety of cycling (OR: 3.70, 95% CI: 1.44, 9.50) were associated with taking up alternatives to the car. Interventions to improve the safety of routes and convenience of public transport may help promote active commuting and should be evaluated. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.
Simulation of Population-Based Commuter Exposure to NO2 Using Different Air Pollution Models
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Martina S. Ragettli
2014-05-01
Full Text Available We simulated commuter routes and long-term exposure to traffic-related air pollution during commute in a representative population sample in Basel (Switzerland, and evaluated three air pollution models with different spatial resolution for estimating commute exposures to nitrogen dioxide (NO2 as a marker of long-term exposure to traffic-related air pollution. Our approach includes spatially and temporally resolved data on actual commuter routes, travel modes and three air pollution models. Annual mean NO2 commuter exposures were similar between models. However, we found more within-city and within-subject variability in annual mean (±SD NO2 commuter exposure with a high resolution dispersion model (40 ± 7 µg m−3, range: 21–61 than with a dispersion model with a lower resolution (39 ± 5 µg m−3; range: 24–51, and a land use regression model (41 ± 5 µg m−3; range: 24–54. Highest median cumulative exposures were calculated along motorized transport and bicycle routes, and the lowest for walking. For estimating commuter exposure within a city and being interested also in small-scale variability between roads, a model with a high resolution is recommended. For larger scale epidemiological health assessment studies, models with a coarser spatial resolution are likely sufficient, especially when study areas include suburban and rural areas.
The association between access to public transportation and self-reported active commuting.
Djurhuus, Sune; Hansen, Henning S; Aadahl, Mette; Glümer, Charlotte
2014-12-05
Active commuting provides routine-based regular physical activity which can reduce the risk of chronic diseases. Using public transportation involves some walking or cycling to a transit stop, transfers and a walk to the end location and users of public transportation have been found to accumulate more moderate physical activity than non-users. Understanding how public transportation characteristics are associated with active transportation is thus important from a public health perspective. This study examines the associations between objective measures of access to public transportation and self-reported active commuting. Self-reported time spent either walking or cycling commuting each day and the distance to workplace were obtained for adults aged 16 to 65 in the Danish National Health Survey 2010 (n = 28,928). Access to public transportation measures were computed by combining GIS-based road network distances from home address to public transit stops an integrating their service level. Multilevel logistic regression was used to examine the association between access to public transportation measures and active commuting. Distance to bus stop, density of bus stops, and number of transport modes were all positively associated with being an active commuter and with meeting recommendations of physical activity. No significant association was found between bus services at the nearest stop and active commuting. The results highlight the importance of including detailed measurements of access to public transit in order to identify the characteristics that facilitate the use of public transportation and active commuting.
Reducing drag of a commuter train, using engine exhaust momentum
Ha, Dong Keun
The objective of this thesis was to perform numerical investigations of two different methods of injecting fluid momentum into the air flow above a commuter train to reduce its drag. Based on previous aerodynamic modifications of heavy duty trucks in improving fuel efficiency, two structural modifications were designed and applied to a Metrolink Services commuter train in the Los Angeles (LA) County area to reduce its drag and subsequently improve fuel efficiency. The first modification was an L-shaped channel, added to the exhaust cooling fan above the locomotive roof to divert and align the exhaust gases in the axial direction. The second modification was adding an airfoil shaped lid over the L-shape channel, to minimize the drag of the perturbed structure, and thus reduce the overall drag. The computational fluid dynamic (CFD) software CCM+ from CD-Adapco with the ?-? turbulence model was used for the simulations. A single train set which consists of three vehicles: one locomotive, one trailer car and one cab car were used. All the vehicles were modeled based on the standard Metrolink fleet train size. The wind speed was at 90 miles per hour (mph), which is the maximum speed for the Orange County Metrolink line. Air was used as the exhaust gas in the simulation. The temperature of the exhausting air emitting out of the cooling fan on the roof was 150 F and the average fan speed was 120 mph. Results showed that with the addition of the lid, momentum injection results in reduced flow separation and pressure recovery behind the locomotive, which reduces the overall drag by at least 30%.
Spontaneous usage of different shortcuts based on the commutativity principle.
Directory of Open Access Journals (Sweden)
Robert Gaschler
Full Text Available Based on research on expertise a person can be said to possess integrated conceptual knowledge when she/he is able to spontaneously identify task relevant information in order to solve a problem efficiently. Despite the lack of instruction or explicit cueing, the person should be able to recognize which shortcut strategy can be applied--even when the task context differs from the one in which procedural knowledge about the shortcut was originally acquired. For mental arithmetic, first signs of such adaptive flexibility should develop already in primary school. The current study introduces a paper-and-pencil-based as well as an eyetracking-based approach to unobtrusively measure how students spot and apply (known shortcut options in mental arithmetic. We investigated the development and the relation of the spontaneous use of two strategies derived from the mathematical concept of commutativity. Children from grade 2 to grade 7 and university students solved three-addends addition problems, which are rarely used in class. Some problems allowed the use of either of two commutativity-based shortcut strategies. Results suggest that from grade three onwards both of the shortcuts were used spontaneously and application of one shortcut correlated positively with application of the other. Rate of spontaneous usage was substantial but smaller than in an instructed variant. Eyetracking data suggested similar fixation patterns for spontaneous an instructed shortcut application. The data are consistent with the development of an integrated concept of the mathematical principle so that it can be spontaneously applied in different contexts and strategies.
Spontaneous usage of different shortcuts based on the commutativity principle.
Gaschler, Robert; Vaterrodt, Bianca; Frensch, Peter A; Eichler, Alexandra; Haider, Hilde
2013-01-01
Based on research on expertise a person can be said to possess integrated conceptual knowledge when she/he is able to spontaneously identify task relevant information in order to solve a problem efficiently. Despite the lack of instruction or explicit cueing, the person should be able to recognize which shortcut strategy can be applied--even when the task context differs from the one in which procedural knowledge about the shortcut was originally acquired. For mental arithmetic, first signs of such adaptive flexibility should develop already in primary school. The current study introduces a paper-and-pencil-based as well as an eyetracking-based approach to unobtrusively measure how students spot and apply (known) shortcut options in mental arithmetic. We investigated the development and the relation of the spontaneous use of two strategies derived from the mathematical concept of commutativity. Children from grade 2 to grade 7 and university students solved three-addends addition problems, which are rarely used in class. Some problems allowed the use of either of two commutativity-based shortcut strategies. Results suggest that from grade three onwards both of the shortcuts were used spontaneously and application of one shortcut correlated positively with application of the other. Rate of spontaneous usage was substantial but smaller than in an instructed variant. Eyetracking data suggested similar fixation patterns for spontaneous an instructed shortcut application. The data are consistent with the development of an integrated concept of the mathematical principle so that it can be spontaneously applied in different contexts and strategies.
Mathot, S
2008-01-01
The aim of this paper is to describe the vacuum brazing procedure used at CERN for the brazing of Radio Frequency Quadrupole (RFQ). The RFQ is made of high precision machined OFE copper pieces assembled together. Vacuum brazing is one of the most promising techniques used to join the individual components leading to vacuum tightness and high precision alignment. The RFQ modules brazed at CERN are made of four 100 or 120 cm long vanes (two major and two minor vanes). Our brazing procedure consists of two steps. The first step involves the brazing of the four vanes in a horizontal position. The second step consists of brazing the vacuum stainless steel flanges to the copper structure in a vertical position. The paper describes the problems encountered with the alignment and the vacuum tightness. The difficulties related to the stress relaxation of the machined copper pieces during the brazing heat treatment are discussed. In addition, the solutions developed to improve the alignment of the brazed RFQâs are...
Measurement of partial pressures in vacuum technology and vacuum physics
Huber, W. K.
1986-01-01
It is pointed out that the measurement of gaseous pressures of less than 0.0001 torr is based on the ionization of gas atoms and molecules due to collisions with electrons. The particle density is determined in place of the pressure. The ionization cross sections for molecules of various gases are discussed. It is found that the true pressure in a vacuum system cannot be determined with certainty if it is unknown which gas is present. Effects of partial pressure determination on the condition of the vacuum system are discussed together with ion sources, systems of separation, and ion detection.
Private and public modes of bicycle commuting: a perspective on attitude and perception.
Curto, A; de Nazelle, A; Donaire-Gonzalez, D; Cole-Hunter, T; Garcia-Aymerich, J; Martínez, D; Anaya, E; Rodríguez, D; Jerrett, M; Nieuwenhuijsen, M J
2016-08-01
Public bicycle-sharing initiatives can act as health enhancement strategies among urban populations. The aim of the study was to determine which attitudes and perceptions of behavioural control toward cycling and a bicycle-sharing system distinguish commuters with a different adherence to bicycle commuting. The recruitment process was conducted in 40 random points in Barcelona from 2011 to 2012. Subjects completed a telephone-based questionnaire including 27 attitude and perception statements. Based on their most common one-way commute trip and willingness to commute by bicycle, subjects were classified into Private Bicycle (PB), public bicycle or Bicing Bicycle (BB), Willing Non-bicycle (WN) and Non-willing Non-bicycle (NN) commuters. After reducing the survey statements through principal component analysis, a multinomial logistic regression model was obtained to evaluate associations between attitudinal and commuter sub-groups. We included 814 adults in the analysis [51.6% female, mean (SD): age 36.6 (10.3) years]. BB commuters were 2.0 times [95% confidence interval (CI) = 1.1-3.7] less likely to perceive bicycle as a quick, flexible and enjoyable mode compared to PB. BB, WN and NN were 2.5 (95% CI = 1.46-4.24), 2.6 (95% CI = 1.53-4.41) and 2.3 times (95% CI = 1.30-4.10) more likely to perceive benefits of using public bicycles (bicycle maintenance and parking avoidance, low cost and no worries about theft and vandalism) than did PB. Willing non-bicycle and public-bicycle commuters had more favourable perception toward public-shared bicycles compared to private cyclists. Hence, public bicycles may be the impetus for those willing to start bicycle commuting, thereby increasing physical activity levels. © The Author 2016. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.
ISRU Soil Mechanics Vacuum Facility: Soil Bin Preparation and Simulant Strength Characterization
Kleinhenz, Julie; Wilkinson, Allen
2012-01-01
Testing in relevant environments is key to exploration mission hardware development. This is true on both the component level (in early development) and system level (in late development stages). During ISRU missions the hardware will interface with the soil (digging, roving, etc) in a vacuum environment. A relevant test environment will therefore involve a vacuum chamber with a controlled, conditioned simulant bed. However, in earth-based granular media, such as lunar soil simulant, gases trapped within the material pore structures and water adsorbed to all particle surfaces will release when exposed to vacuum. Early vacuum testing has shown that this gas release can occur violently, which loosens and weakens the simulant, altering the consolidation state. The Vacuum Facility #13, a mid-size chamber (3.66m tall, 1.5m inner diameter) at the NASA Glenn Research Center has been modified to create a soil mechanics test facility. A 0.64m deep by 0.914m square metric ton bed of lunar simulant was placed under vacuum using a variety of pumping techniques. Both GRC-3 and LHT-3M simulant types have been used. An electric cone penetrometer was used to measure simulant strength properties at vacuum including: cohesion, friction angle, bulk density and shear modulus. Simulant disruptions, caused by off gassing, affected the strength properties, but could be mitigated by reducing pump rate. No disruptions were observed at pressures below 2.5Torr, regardless of the pump rate. However, slow off gassing of the soil lead to long test times, a full week, to reach 10-5Torr. This work highlights the need for robotic machine-simulant hardware and operations in vacuum to expeditiously perform (sub-)systems tests.
Development and Testing of an ISRU Soil Mechanics Vacuum Test Facility
Kleinhenz, Julie E.; Wilkinson, R. Allen
2014-01-01
For extraterrestrial missions, earth based testing in relevant environments is key to successful hardware development. This is true for both early component level development and system level integration. For In-Situ Resource Utilization (ISRU) on the moon, hardware must interface with the surface material, or regolith, in a vacuum environment. A relevant test environment will therefore involve a vacuum chamber with a controlled, properly conditioned bed of lunar regolith simulant. However, in earth-based granular media, such as lunar regolith simulant, gases trapped within the material pore structures and water adsorbed to all particle surfaces will release when exposed to vacuum. Early vacuum testing has shown that this gas release can occur violently, which loosens and weakens the simulant, altering the consolidation state. A mid-size chamber (3.66 m tall, 1.5 m inner diameter) at the NASA Glenn Research Center has been modified to create a soil mechanics test facility. A 0.64 m deep by 0.914 m square metric ton bed of lunar simulant was placed under vacuum using a variety of pumping techniques. Both GRC-3 and LHT-3M simulant types were used. Data obtained from an electric cone penetrometer can be used to determine strength properties at vacuum including: cohesion, friction angle, bulk density and shear modulus. Simulant disruptions, caused by off-gassing, affected the strength properties, but could be mitigated by reducing pump rate. No disruptions were observed at pressures below 2.5 Torr, regardless of the pump rate. The slow off-gassing of the soil at low pressure lead to long test times; a full week to reach 10(exp -5) Torr. Robotic soil manipulation would enable multiple ISRU hardware test within the same vacuum cycle. The feasibility of a robotically controlled auger and tamper was explored at vacuum conditions.
Correlating off-axis tension tests to shear modulus of wood-based panels
Edmond P. Saliklis; Robert H. Falk
2000-01-01
The weakness of existing relationships correlating off-axis modulus of elasticity E q to shear modulus G 12 for wood composite panels is demonstrated through presentation of extensive experimental data. A new relationship is proposed that performs better than existing equations found in the literature. This relationship can be manipulated to calculate the shear modulus...
Resin composites: Modulus of elasticity and marginal quality.
Benetti, Ana R; Peutzfeldt, Anne; Lussi, Adrian; Flury, Simon
2014-09-01
To investigate how the modulus of elasticity of resin composites influences marginal quality in restorations submitted to thermocyclic and mechanical loading. Charisma, Filtek Supreme XTE and Grandio were selected as they were found to possess different moduli of elasticity but quite similar polymerization contraction. MOD cavities (n=30) were prepared in extracted premolars, restored and then subjected to thermocyclic and mechanical loading. Marginal quality of the restorations before and after loading was analyzed on epoxy replicas under a scanning electron microscope. The percentage of gap-free margins and occurrence of paramarginal fractures were registered. Modulus of elasticity and polymerization contraction were analyzed with parametric and margins with nonparametric ANOVA and post hoc Tukey HSD or Wilcoxon rank-sum tests, respectively. The number of paramarginal fractures was analyzed with exact Fisher tests (α=0.05). Grandio demonstrated significantly more gap-free enamel margins than Charisma and Filtek Supreme XTE, before and after loading (p0.05). No significant effect of resin composite (p=0.81) on the quality of dentine margins was observed, before or after loading. Deterioration of all margins was evident after loading (pmodulus of elasticity resulted in the highest number of gap-free enamel margins but with an increased incidence of paramarginal enamel fractures. The results from this study suggest that the marginal quality of restorations can be improved by the selection of a resin composite with modulus of elasticity close to that of dentine, although an increase in paramarginal enamel fractures can result as a consequence. Copyright © 2014 Elsevier Ltd. All rights reserved.
Mechanical Components from Highly Recoverable, Low Apparent Modulus Materials
Padula, Santo, II (Inventor); Noebe, Ronald D. (Inventor); Stanford, Malcolm K. (Inventor); DellaCorte, Christopher (Inventor)
2015-01-01
A material for use as a mechanical component is formed of a superelastic intermetallic material having a low apparent modulus and a high hardness. The superelastic intermetallic material is conditioned to be dimensionally stable, devoid of any shape memory effect and have a stable superelastic response without irrecoverable deformation while exhibiting strains of at least 3%. The method of conditioning the superelastic intermetallic material is described. Another embodiment relates to lightweight materials known as ordered intermetallics that perform well in sliding wear applications using conventional liquid lubricants and are therefore suitable for resilient, high performance mechanical components such as gears and bearings.
Supernovae Light Curves: An Argument for a New Distance Modulus
Jensen, Jerry W.
2004-01-01
Supernovae Ia (SNe Ia) light curves have been used to prove the universe is expanding. As standard candles, SNe Ia appear to indicate the rate of expansion has increased in the past and is now decreasing. This independent evaluation of SNe Ia light curves demonstrates a Malmquist Type II bias exists in the body of supernova data. If this bias is properly addressed, there is very little budget for time dilation in the light curves of supernova. A non-relativistic distance modulus is proposed, ...
The photon-neutrino interaction in non-commutative gauge field theory and astrophysical bounds
Schupp, Peter; Trampetic, Josip; Wess, Julius; Raffelt, Georg
2004-01-01
In this letter we propose a possible mechanism of left- and right-handed neutrino couplings to photons, which arises quite naturally in non-commutative gauge field theory. We estimate the predicted additional energy-loss in stars induced by space-time non-commutativity. The usual requirement that any new energy-loss mechanism in globular stellar clusters should not excessively exceed the standard neutrino losses implies a scale of non-commutative gauge theory above the scale of weak interacti...
Young's Moduli of Cold and Vacuum Plasma Sprayed Metallic Coatings
Raj, S. V.; Pawlik, R.; Loewenthal, W.
2009-01-01
Monolithic metallic copper alloy and NiCrAlY coatings were fabricated by either the cold spray (CS) or the vacuum plasma spray (VPS) deposition processes. Dynamic elastic modulus property measurements were conducted on these monolithic coating specimens between 300 K and 1273 K using the impulse excitation technique. The Young's moduli decreased almost linearly with increasing temperature at all temperatures except in the case of the CS Cu-23%Cr-5%Al and VPS NiCrAlY, where deviations from linearity were observed above a critical temperature. It was observed that the Young's moduli for VPS Cu-8%Cr were larger than literature data compiled for Cu. The addition of 1%Al to Cu- 8%Cr significantly increased its Young's modulus by 12 to 17% presumably due to a solid solution effect. Comparisons of the Young s moduli data between two different measurements on the same CS Cu- 23%Cr-5%Al specimen revealed that the values measured in the first run were about 10% higher than those in the second run. It is suggested that this observation is due to annealing of the initial cold work microstructure resulting form the cold spray deposition process.
Microscale Digital Vacuum Electronic Gates
Manohara, Harish (Inventor); Mojarradi, Mohammed M. (Inventor)
2014-01-01
Systems and methods in accordance with embodiments of the invention implement microscale digital vacuum electronic gates. In one embodiment, a microscale digital vacuum electronic gate includes: a microscale field emitter that can emit electrons and that is a microscale cathode; and a microscale anode; where the microscale field emitter and the microscale anode are disposed within at least a partial vacuum; where the microscale field emitter and the microscale anode are separated by a gap; and where the potential difference between the microscale field emitter and the microscale anode is controllable such that the flow of electrons between the microscale field emitter and the microscale anode is thereby controllable; where when the microscale anode receives a flow of electrons, a first logic state is defined; and where when the microscale anode does not receive a flow of electrons, a second logic state is defined.
Carbon nanotubes based vacuum gauge
Rudyk, N. N.; Il’in, O. I.; Il’ina, M. V.; Fedotov, A. A.; Klimin, V. S.; Ageev, O. A.
2017-11-01
We have created an ionization type Vacuum gauge with sensor element based on an array of vertically aligned carbon nanotubes. Obtained asymmetrical current-voltage characteristics at different voltage polarity on the electrode with the CNTs. It was found that when applying a negative potential on an electrode with the CNTs, the current in the gap is higher than at a positive potential. In the pressure range of 1 ÷ 103 Torr vacuum gauge sensitivity was 6 mV/Torr (at a current of 4.5·10-5 A) and in the range of 10-5 ÷ 1 Torr was 10 mV/Torr (at a current of 1.3·10-5 A). It is shown that the energy efficiency of vacuum gauge can be increased in the case where electrode with CNT operates as an emitter of electrons.
Vacuum Cleaner Fan Being Improved
Tweedt, Daniel L.
1997-01-01
As part of the technology utilization program at the NASA Lewis Research Center, efforts are underway to transfer aerospace technologies to new areas of practical application. One such effort involves using advanced computational fluid dynamics (CFD) codes for turbomachinery to analyze the internal fluid dynamics of low-speed fans and blowers. This year, the Kirby Company in Cleveland, Ohio, approached NASA with a request for technologies that could help them improve their vacuum cleaners. Of particular interest to Kirby is the high-frequency blade-passing noise generation of their vacuum cleaner fan at low airflow rates.
Complex modulus estimation respecting causality: Application to viscoelastic bars
Collet, P.; Gary, G.; Lundberg, B.; Mohr, D.
2012-08-01
The identification of linear visco-elasticity models mostly focuses on the real and imaginary parts of the Young's modulus. Many methods have been proposed in the past to identify these material model parameters from experiments. However, when these parameters are determined independently, they are likely to violate the principle of causality. The present work presents a method that accounts for the constraints of causality and positivity of dissipation rate. The proposed method is based on a finite set of n measured angular frequencies and complex moduli. It includes a noise reduction procedure and provides a rheological 2p + 1)-parameter model with p modulus on the positive imaginary frequency axis are determined by p parameters which are obtained as the common positive zeros of a special class of rational functions, while the remaining parameters are obtained from a least squares fit. The level of refinement of the rheological model, expressed by p, is not an assumed value but a result of the method. The method is applied to an impact test with a Nylon bar specimen. In this case, data at the n = 29 lowest resonance frequencies resulted in a rheological model with 14 parameters (p = 6). The validity of the method is checked through supplementary experimental results at low frequencies.
Elastomer modulus and dielectric strength scaling with sample thickness
Larson, Kent
2015-04-01
Material characteristics such as adhesion and dielectric strength have well recognized dependencies on material thickness. There is disagreement, however, on the scale: the long held dictum that dielectric strength is inversely proportional to the square root of sample thickness has been shown to not always hold true for all materials, nor for all possible thickness regions. In D-EAP applications some studies have postulated a "critical thickness" below which properties show significantly less thickness dependency. While a great deal of data is available for dielectric strength, other properties are not nearly as well documented as samples get thinner. In particular, elastic modulus has been found to increase and elongation to decrease as sample thickness is lowered. This trend can be observed experimentally, but has been rarely reported and certainly does not appear in typical suppliers' product data sheets. Both published and newly generated data were used to study properties such as elastic modulus and dielectric strength vs sample thickness in silicone elastomers. Several theories are examined to explain such behavior, such as the impact of defect size and of common (but not well reported) concentration gradients that occur during elastomer curing that create micron-sized layers at the upper and lower interfaces with divergent properties to the bulk material. As Dielectric Electro-Active Polymer applications strive to lower and lower material thickness, changing mechanical properties must be recognized and taken into consideration for accurate electro-mechanical predictions of performance.
Gases and vacua handbook of vacuum physics
Beck, A H
2013-01-01
Handbook of Vacuum Physics, Volume 1: Gases and Vacua provides information on the many aspects of vacuum technology, from material on the quantum theoretical aspects of the complex semi-conductors used for thermionic and photo-electric emission to data on the performance of commercially available pumps, gauges, and high-vacuum materials. The handbook satisfies the need of workers using vacuum apparatuses or works on the diverse applications of high-vacuum technology in research and industry. The book is a compilation of long articles prepared by experts in vacuum technology. Sufficient theoret
Non-classical Response and Shear Modulus of Solid 4He
Kim, D. Y.; Kwon, S.; Choi, H.; Choi, W. S.; Kim, E.; Kim, H. C.
2010-03-01
The relation between the nonclassical rotational inertia (NCRI) and the shear modulus increase of solid 4He was investigated. A pair of piezoelectric transducers is positioned in the center of a torsional oscillator to measure the shear modulus. We observe the NCRI and the shear modulus increases below 200mK with similar temperature, measurement drive, and frequency dependence. The drive and frequency dependence in the shear modulus increase can be understood by the model of thermally assisted unpinning of dislocations from impurities. However, the shear modulus increase is found to be insufficient to explain the magnitude of the NCRI. In addition, no linear correlation between the magnitude of the NCRI and the shear modulus increase is found and the magnitude of shear modulus shows a rather negative correlation with that of NCRI.
EnviroAtlas - Commute Time to Work by Census Block Group for the Conterminous United States
U.S. Environmental Protection Agency — This EnviroAtlas dataset portrays the commute time of workers to their workplace for each Census Block Group (CBG) during 2008-2012. Data were compiled from the...
INdAM Meeting on Homological and Computational Methods in Commutative Algebra
Gubeladze, Joseph; Römer, Tim
2017-01-01
This volume collects contributions by leading experts in the area of commutative algebra related to the INdAM meeting “Homological and Computational Methods in Commutative Algebra” held in Cortona (Italy) from May 30 to June 3, 2016 . The conference and this volume are dedicated to Winfried Bruns on the occasion of his 70th birthday. In particular, the topics of this book strongly reflect the variety of Winfried Bruns’ research interests and his great impact on commutative algebra as well as its applications to related fields. The authors discuss recent and relevant developments in algebraic geometry, commutative algebra, computational algebra, discrete geometry and homological algebra. The book offers a unique resource, both for young and more experienced researchers seeking comprehensive overviews and extensive bibliographic references.
Energy Technology Data Exchange (ETDEWEB)
Brownstone, D.; Golob, T.F. (California Univ., Irvine, CA (USA))
1992-03-01
The effects of certain incentives designed to promote ridesharing on work trips to reduce congestion and air pollution are studies. Ordered probit discrete choice models of commuters' mode choices (always rideshare, sometimes rideshare, and always drive alone) are estimated using a new study of full-time workers' commuting behavior in the greater Los Angeles area. We find that women and those who have larger households with multiple workers, longer commutes, and larger worksites are more likely to rideshare. Partial equilibrium policy simulations with our model indicate that providing all workers with reserved parking, ridesharing subsidies, guaranteed rides home, and high-occupancy vehicle lanes would reduce drive-alone commuting between 11 and 18 percent. 1 app., 6 tabs., 22 refs.
Daily time budgets of long-distance commuting workers in Tokyo megalopolis.
Umezaki, M; Ishimaru, H; Ohtsuka, R
1999-01-01
In Tokyo Megalopolis, long-distance commuting between residences in the suburbs and work places in the centre of the city was examined. Using a questionnaire, heads of household in two suburbs were asked about the influences of long commuting hours on their daily time budgets. The results showed that on workdays, the workers who spent longer commuting rose and left home for work earlier, and came back home and retired later; accordingly, both time spent on in-home activities on workdays and hours slept on the day before a workday were shorter. Comparison of time budgets between the subjects who work 5 and 6 days per week revealed more vulnerable influences of long commuting hours in the former than the latter. The expected health consequences of these findings are discussed from a biosocial/human ecological viewpoint.
Energy Technology Data Exchange (ETDEWEB)
Oh, Seok Gyu; Choi, Tae Wan [Chinju National University (Korea); Lee, Jong Gun [Kumho Electronics Co., Ltd. (Korea)
2001-06-01
SRM drives generate large vibration and acoustic noise because it is rotated by step pulse mmf and switching commutation mechanism. The main vibration source of SRM drive is generated by rapidly variation of radial force when phase winding current is extinguished for commutation action. So the rapidly variation of radial force is repressed firstly to reduce vibrating force of SRM drive. This paper suggests an SRM excitation scheme using unidirect-short compensation winding to reduce vibration of the motor. The motor is excited by a two stage commutation method during commutation period. This reduction effect of vibration is verified with the result obtained in the test of prototype machine. (author). 7 refs., 11 figs.
Associations between active commuting to school and objectively measured physical activity
DEFF Research Database (Denmark)
Børrestad L, Anita Bjørkelund; Ostergaard, Lars; Andersen, Lars Bo
2013-01-01
. Physical activity was measured with cycle computers and accelerometers for 4 days. Mode of commuting and demographic information was self-reported in a questionnaire. Results: Children who reported to cycle to school spent significantly more time cycling than those who walked to school, 53.6 (SD = ± 33......Background: To provide more accurate assessment of commuting behavior and potential health effect, it is important to have accurate methods. Therefore, the current study aimed to a) compare questionnaire reported mode of commuting with objectively measured data from accelerometer and cycle computer......, b) compare moderate vigorous physical activity (MVPA) among children cycling vs. walking to school, and c) thus calculate possible underestimated MVPA, when using accelerometers to measure commuter cycling. Methods: A total of 78 children, average age 11.4 (SD = 0.5), participated in the study...
Devi, M. K.
2017-06-01
In order to alleviate the negative impacts of motorized vehicle use as well as create sustainable environment within campus area, it is pivotal to encourage mode shifting among university students. Active transport modes such as walking, cycling, and using public transport can be considered as alternative modes. This paper tried to identify the potential to increase active commuting in UGM by understanding student’s travel behavior. ANOVA test was employed to identify the perceptions between students across residential zones toward motivators and barriers to actively commute. The findings were used to propose strategies for increasing active commuting level in UGM, which are: reducing barriers to actively commute, improving public transport services, improving walking and cycling facilities, and introducing programs to discourage motorized vehicle use.
Clemons, J. M.; Penn, B. G.; Ledbetter, Frank E., III; Daniels, J. G.
1987-01-01
Improvement upon recommended procedures saves time and expense. Autoclave molding in vacuum bag cleaner if adhesive-backed covering placed around caul plate as well as on mold plate. Covering easy to remove after curing and leaves caul plate free of resin deposits.
Brine Distribution after Vacuum Saturation
DEFF Research Database (Denmark)
Hedegaard, Kathrine; Andersen, Bertel Lohmann
1999-01-01
Experiments with the vacuum saturation method for brine in plugs of chalk showed that a homogeneous distribution of brine cannot be ensured at saturations below 20% volume. Instead of a homogeneous volume distribution the brine becomes concentrated close to the surfaces of the plugs...
Quantum Vacuum Structure and Cosmology
Energy Technology Data Exchange (ETDEWEB)
Rafelski, Johann; Labun, Lance; Hadad, Yaron; /Arizona U. /Munich U.; Chen, Pisin; /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC
2011-12-05
Contemporary physics faces three great riddles that lie at the intersection of quantum theory, particle physics and cosmology. They are: (1) The expansion of the universe is accelerating - an extra factor of two appears in the size; (2) Zero-point fluctuations do not gravitate - a matter of 120 orders of magnitude; and (3) The 'True' quantum vacuum state does not gravitate. The latter two are explicitly problems related to the interpretation and the physical role and relation of the quantum vacuum with and in general relativity. Their resolution may require a major advance in our formulation and understanding of a common unified approach to quantum physics and gravity. To achieve this goal we must develop an experimental basis and much of the discussion we present is devoted to this task. In the following, we examine the observations and the theory contributing to the current framework comprising these riddles. We consider an interpretation of the first riddle within the context of the universe's quantum vacuum state, and propose an experimental concept to probe the vacuum state of the universe.
LEP vacuum chamber, early prototype
CERN PhotoLab
1978-01-01
The same vacuum chamber as in 7810256, read the detailed description there. Here, the 4 strip-shaped ion-getter pumps are poised at the entrance to their slots. Ion-getter pumps were not retained, thermal getter pumps were chosen instead (see 8301153 and 8305170).
Katarina Anthony
2013-01-01
Last month, the Vacuum, Surfaces and Coatings (VSC) group was tasked with an unusually delicate operation in the LHCb experiment cavern: removing the LHC beam pipe while keeping the sensitive Vertex Locator vacuum vessel (VELO) completely isolated from the action. The VSC group seal off the VELO beam pipe with a flange. Image: Gloria Corti. LHCb’s VELO detector is one of the crown jewels of the experiment. With detector elements surrounded by a vacuum, it gets as close as 5 cm from the beam. Fantastic for physics, but difficult for all-important access. “Because of the sensitivity of the VELO detector and its proximity to the beam, the collaboration decided not to bake (see box) its portion of the beam pipe,” says Giulia Lanza (TE-VSC-LBV), the expert in charge of the beam vacuum operation. “Our group was therefore asked to remove the rest of the LHC beam pipe while keeping the VELO portion of the pipe completely isolated. This work...
Vacuum Stability of Standard Model^{++}
Anchordoqui, Luis A.; Goldberg, Haim; Huang, Xing; Lust, Dieter; Taylor, Tomasz R.; Vlcek, Brian
2013-01-01
The latest results of the ATLAS and CMS experiments point to a preferred narrow Higgs mass range (m_h \\simeq 124 - 126 GeV) in which the effective potential of the Standard Model (SM) develops a vacuum instability at a scale 10^{9} -10^{11} GeV, with the precise scale depending on the precise value of the top quark mass and the strong coupling constant. Motivated by this experimental situation, we present here a detailed investigation about the stability of the SM^{++} vacuum, which is characterized by a simple extension of the SM obtained by adding to the scalar sector a complex SU(2) singlet that has the quantum numbers of the right-handed neutrino, H", and to the gauge sector an U(1) that is broken by the vacuum expectation value of H". We derive the complete set of renormalization group equations at one loop. We then pursue a numerical study of the system to determine the triviality and vacuum stability bounds, using a scan of 10^4 random set of points to fix the initial conditions. We show that, if there...
Vacuum assisted closure in coloproctology
Bemelman, W.A.
2009-01-01
Vacuum-assisted closure has earned its indications in coloproctology. It has been described with variable results in the treatment of large perineal defects after abdominoperineal excision, in the treatment of stoma dehiscence and perirectal abscesses. The most promising indication for
HIGH PRODUCTIVITY VACUUM BLASTING SYSTEM
Energy Technology Data Exchange (ETDEWEB)
William S. McPhee
1999-05-31
The objective of this project is to improve the productivity and lower the expense of existing vacuum blasting technology. This technology is used to remove radioactive contamination, PCBs, and lead-based paint and provides worker protection by continuously recycling the material and dust for the decontamination tasks. The proposed work would increase the cleaning rate and provide safe and cost-effective decontamination of the DOE sites. This work focuses on redesigning and improving existing vacuum blasting technology including blast head nozzles, ergonomic handling of the blast head by reducing its weight; brush-ring design, vacuum level regulator, efficiency of the dust separator, and operational control sensors. The redesign is expected to enhance the productivity and economy of the vacuum blasting system by at least 50% over current vacuum blasting systems. There are three phases in the project. Phase I consists of developing and testing mathematical models. Phase II consists of pre-prototype design and fabrication and pre-prototype unit testing. Phase III consists of prototype design and field verification testing. In phase I, mathematical models are developed and analyzed for the nozzle, blast head, wind curtain, and dust separator, first as individual devices and then combined as an integrated model. This allows study of respective airflow and design parameters. The Contractor shall, based on the results of the mathematical modeling studies, design experimental models of the components and test these models. In addition, the Contractor shall develop sensors to detect the relationship of the blast head to the blast surfaces and controls to minimize the dependency on an operator's skill and judgment to obtain optimum positioning, as well as real-time characterization sensors to determine as the blast head is moving the depth to which coatings must be removed, thereby improving production and minimizing waste. In phase II, the Contractor shall design and
On noncommutative deformations, cohomology of color-commutative algebras and formal smoothness
Gohr, Aron Samuel
2009-01-01
The main topic under study in the present work is the deformation theory of color algebras. Color algebras are generalized analogues of associative superalgebras, where the underlying grading can be over an arbitrary abelian group and the Koszul sign is replaced by a bicharacter from the group into the base ring. A special case of particular interest are color-commutative algebras, which satisfy a commutation identity similar to (but much more general than) supercommutative algebras. Examples...
Group-specific analysis of commuting in the most disadvantaged areas of Hungary
Alpek B., Levente; Tésits, Róbert; Bokor, László
2016-01-01
The study aims to examine the commuting opportunities of the most disadvantaged job seeker groups living in Hungary's most disadvantaged regions, as well as Hungary’s spatial and group-specific boundary conditions. The study also aims to develop and present an indexation process (fMFÁ model), allowing the measurement of the mobility degree of different territorial units (in this case, the municipalities) and effects of certain factors determining commuting (transport subsidies, individual cho...
Private and public modes of bicycle commuting: a perspective on attitude and perception.
Curto, A.; De Nazelle, A.; Donaire-Gonzalez, D; Cole-Hunter, T; Garcia-Aymerich, J.; Mart?nez, D; Anaya, E.; Rodr?guez, D; Jerrett, M.; Nieuwenhuijsen, MJ
2016-01-01
BACKGROUND: Public bicycle-sharing initiatives can act as health enhancement strategies among urban populations. The aim of the study was to determine which attitudes and perceptions of behavioural control toward cycling and a bicycle-sharing system distinguish commuters with a different adherence to bicycle commuting.? METHODS: The recruitment process was conducted in 40 random points in Barcelona from 2011 to 2012. Subjects completed a telephone-based questionnaire including 27 attitude and...
The effects of sprawl on private-vehicle commuting distances and times
Edmund J Zolnik
2011-01-01
Sprawl is a well-known consequence of the suburbanization of the United States population. However, only recently have scholars shown interest in the effects of sprawl on transportation outcomes. For example, little research on how sprawl affects private-vehicle commuting distances and times is evident in the literature. To explore further the relationship between sprawl and private-vehicle commuting distances and times, a multilevel approach is adopted. Using microdata for households and mac...
Directory of Open Access Journals (Sweden)
Hansson Erik
2011-10-01
Full Text Available Abstract Background The need for a mobile workforce inevitably means that the length of the total work day (working and traveling time will increase, but the health effects of commuting have been surprisingly little studied apart from perceived stress and the benefits of physically active commuting. Methods We used data from two cross-sectional population-based public health surveys performed in 2004 and 2008 in Scania, Sweden (56% response rate. The final study population was 21, 088 persons aged 18-65, working > 30 h/week. Duration (one-way and mode of commuting were reported. The outcomes studied were perceived poor sleep quality, everyday stress, low vitality, mental health, self-reported health, and absence from work due to sickness during the past 12 months. Covariates indicating socioeconomic status and family situation, overtime, job strain and urban/rural residency were included in multivariate analyses. Subjects walking or cycling to work Results Monotonous relations were found between duration of public transport commuting and the health outcomes. For the category commuting > 60 min odds ratios (ORs ranged from 1.2 - 1.6 for the different outcomes. For car commuting, the relationships were concave downward or flat, with increasing subjective health complaints up to 30-60 min (ORs ranging from 1.2 - 1.4, and lower ORs in the > 60 min category. A similar concave downward relationship was observed for sickness absence, regardless of mode of transport. Conclusions The results of this study are concordant with the few earlier studies in the field, in that associations were found between commutation and negative health outcomes. This further demonstrates the need to consider the negative side-effects of commuting when discussing policies aimed at increasing the mobility of the workforce. Studies identifying population groups with increased susceptibility are warranted.
Ohtsuka, R; Umezaki, M
1993-06-01
Census data was analyzed for 20 municipalities along the Tohoku Line in Tokyo Megalopolis to elucidate the changes in the population structure and the commuting situation in the last two decades. The major findings were: (1) the changing pattern of population structure markedly varied among the municipalities, and (2) the long-distance commuting workers have increased particularly among those 50 km or more from central Tokyo.
Effects of Light and Commuter Rail Transit on Land Prices: Experiences in San Diego County
Cervero, Robert
2006-01-01
Using hedonic price models, appreciable land-value premiums were found for multiple land uses in different rail corridors of San Diego County. The most appreciable benefits were for condominiums and single-family housing near commuter-rail stations in the north county, multi-family housing near light-rail stations, and commercial properties near downtown commuter-rail stations and light-rail stops in the Mission Valley. Elsewhere, commercial properties accrued small or even negative capitaliz...
Exotic Galilean symmetry in the non-commutative plane and the Hall effect
Energy Technology Data Exchange (ETDEWEB)
Duval, C. [Centre de Physique Theorique, CNRS, Luminy, Marseille (France); Horvathy, P.A. [Laboratoire de Mathematiques et de Physique Theorique, Universite de Tours, Tours (France)
2001-11-30
Quantum mechanics in the non-commutative plane is shown to admit the 'exotic' symmetry of the doubly centrally extended Galilei group. When coupled to a planar magnetic field whose strength is the inverse of the non-commutative parameter, the system becomes singular, and 'Faddeev-Jackiw' reduction yields the 'Chern-Simons' mechanics of Dunne et al. The reduced system moves according to the Hall law. (author)
Tiryaki, Sebahattin; Aras, Uğur; Kalaycıoğlu, Hülya; Erişir, Emir; Aydın, Aytaç
2017-07-01
Determining the mechanical properties of particleboard has gained a great importance due to its increasing usage as a building material in recent years. This study aims to develop artificial neural network (ANN) and multiple linear regression (MLR) models for predicting modulus of rupture (MOR) and modulus of elasticity (MOE) of particleboard depending on different pressing temperature, pressing time, pressing pressure and resin type. Experimental results indicated that the increased pressing temperature, time and pressure in manufacturing process generally improved the mechanical properties of particleboard. It was also seen that ANN and MLR models were highly successful in predicting the MOR and MOE of particleboard under given conditions. On the other hand, a comparison between ANN and MLR revealed that the ANN was superior compared to the MLR in predicting the MOR and MOE. Finally, the findings of this study are expected to provide beneficial insights for practitioners to better understand usability of such composite materials for engineering applications and to better assess the effects of pressing conditions on the MOR and MOE of particleboard.
Vacuum polarization and Hawking radiation
Rahmati, Shohreh
Quantum gravity is one of the interesting fields in contemporary physics which is still in progress. The purpose of quantum gravity is to present a quantum description for spacetime at 10-33cm or find the 'quanta' of gravitational interaction.. At present, the most viable theory to describe gravitational interaction is general relativity which is a classical theory. Semi-classical quantum gravity or quantum field theory in curved spacetime is an approximation to a full quantum theory of gravity. This approximation considers gravity as a classical field and matter fields are quantized. One interesting phenomena in semi-classical quantum gravity is Hawking radiation. Hawking radiation was derived by Stephen Hawking as a thermal emission of particles from the black hole horizon. In this thesis we obtain the spectrum of Hawking radiation using a new method. Vacuum is defined as the possible lowest energy state which is filled with pairs of virtual particle-antiparticle. Vacuum polarization is a consequence of pair creation in the presence of an external field such as an electromagnetic or gravitational field. Vacuum polarization in the vicinity of a black hole horizon can be interpreted as the cause of the emission from black holes known as Hawking radiation. In this thesis we try to obtain the Hawking spectrum using this approach. We re-examine vacuum polarization of a scalar field in a quasi-local volume that includes the horizon. We study the interaction of a scalar field with the background gravitational field of the black hole in the desired quasi-local region. The quasi-local volume is a hollow cylinder enclosed by two membranes, one inside the horizon and one outside the horizon. The net rate of particle emission can be obtained as the difference of the vacuum polarization from the outer boundary and inner boundary of the cylinder. Thus we found a new method to derive Hawking emission which is unitary and well defined in quantum field theory.
In vivo performance of a reduced-modulus bone cement
Forehand, Brett Ramsey
Total joint replacement has become one of the most common procedures in the area of orthopedics and is often the solution in patients with diseased or injured hip joints. Component loosening is a significant problem and is primarily caused by bone resorption at the bone-cement interface in cemented implants. It is our hypothesis that localized shear stresses are responsible for the resorption. It was previously shown analytically that local stresses at the interface could be reduced by using a cement of lower modulus. A new reduced modulus cement, polybutyl methylmethacrylate (PBMMA), was developed to test the hypothesis. PBMMA was formulated to exist as polybutyl methacrylate filler in a polymethyl methacrylate matrix. The success of PBMMA cement is based largely on the fact that the polybutyl component of the cement will be in the rubbery state at body temperature. In vitro characterization of the cement was undertaken previously and demonstrated a modulus of approximately one-eighth that of conventional bone cement, polymethyl methacrylate (PMMA) and increased fracture toughness. The purpose of this experiment was to perform an in vivo comparison of the two cements. A sheep model was selected. Total hip arthroplasty was performed on 50 ewes using either PBMMA or PMMA. Radiographs were taken at 6 month intervals. At one year, the contralateral femur of each sheep was implanted so that each animal served as its own control, and the animals were sacrificed. The stiffness of the bone-cement interface of the femoral component within the femur was assessed by applying a torque to the femoral component and demonstrated a significant difference in loosening between the cements when the specimens were tested in external rotation (p < 0.007). Evaluation of the mechanical data also suggests that the PBMMA sheep had a greater amount of loosening for each subject, 59% versus 4% for standard PMMA. A radiographic analysis demonstrated more signs of loosening in the PMMA series
Directory of Open Access Journals (Sweden)
Lina Wahlgren
2014-08-01
Full Text Available Background and Aim: Commuting by bicycle could contribute to public health, and route environments may influence this behaviour. Therefore, the aim of this study is to assess the potential associations between appraisals of the overall route environment as hindering or stimulating for bicycle commuting, with both perceptions of commuting route environmental factors in a suburban area and background factors. Methods: The Active Commuting Route Environment Scale (ACRES was used for the assessment of bicycle commuters’ perceptions and appraisals of their route environments in the suburban parts of Greater Stockholm, Sweden. A simultaneous multiple regression analysis was used to assess the relationship between the outcome variable whether the overall route environment hinders or stimulates bicycle commuting and environmental factors (e.g., exhaust fumes, speeds of motor vehicles, greenery, as well as background factors (sex, age, education, income as predictor variables. Results and Conclusions: The results indicate that in suburban areas, the factors aesthetics, greenery and bicycle paths seem to be, independently of each other, stimulating factors for bicycle commuting. On the other hand, flows of motor vehicles, noise, and low “directness” of the route seem to be hindering factors. A comparison of these results with those obtained from an inner urban area points to the importance of studying different types of built-up areas separately.
Lee, Jong-Geon; Khan, Umer Amir; Lee, Ho-Yun; Lim, Sung-Woo; Lee, Bang-Wook
2016-11-01
Commutation failure in line commutated converter based HVDC systems cause severe damages on the entire power grid system. For LCC-HVDC, thyristor valves are turned on by a firing signal but turn off control is governed by the external applied AC voltage from surrounding network. When the fault occurs in AC system, turn-off control of thyristor valves is unavailable due to the voltage collapse of point of common coupling (PCC), which causes the commutation failure in LCC-HVDC link. Due to the commutation failure, the power transfer interruption, dc voltage drop and severe voltage fluctuation in the AC system could be occurred. In a severe situation, it might cause the protection system to block the valves. In this paper, as a solution to prevent the voltage collapse on PCC and to limit the fault current, the application study of resistive superconducting fault current limiter (SFCL) on LCC-HVDC grid system was performed with mathematical and simulation analyses. The simulation model was designed by Matlab/Simulink considering Haenam-Jeju HVDC power grid in Korea which includes conventional AC system and onshore wind farm and resistive SFCL model. From the result, it was observed that the application of SFCL on LCC-HVDC system is an effective solution to mitigate the commutation failure. And then the process to determine optimum quench resistance of SFCL which enables the recovery of commutation failure was deeply investigated.
Nordfjærn, Trond; Simşekoğlu, Özlem; Lind, Hans Brende; Jørgensen, Stig Halvard; Rundmo, Torbjørn
2014-11-01
There is currently scant research on the role of transport priorities, risk perception and worry for travel mode use and preferences. The present study aims to examine these factors in relation to mode use and preferences among Norwegian commuters. A web-based survey was conducted in a randomly obtained representative sample of daily commuters in the extended greater Oslo area (n=690). The results showed that those who prioritized efficiency and flexibility tended to commute by car, while those who prioritized safety and comfort used public (e.g. metro, tram, and train) or active (e.g. walking and cycling) transport. In a free choice scenario, the respondents who prioritized flexibility reported a preference for using a car, whereas those who prioritized safety and comfort preferred public and active transport for their commuter travels. Risk perception of high impact events, such as terrorism and major accidents, as well as risk perception related to personal impact risks (theft, violence etc.) were related to car use on commuter travels. Transport-related worry exerted weak influences on mode use and preferences. Increased speed on rail transport and more frequent departures may be effective in reducing car use on commuter travels. Risk communication should focus on highlighting the low risk of experiencing security and safety issues in the public transport sector, and this message should be complemented by efforts to reduce the probability of negative events affecting public transport. Copyright © 2014 Elsevier Ltd. All rights reserved.
Migration Dilemmas of Islanders: Commuting Leading to Migration or Remaining at Home
Directory of Open Access Journals (Sweden)
Ivan Lajić
2001-09-01
Full Text Available The paper presents and discusses the results of an empirical survey carried out in April 2000 on the islands Prvić, Zlarin and Krapanj in the Šibenik coastal area. These islands are part of a group of islands marked by the highest rates of depopulation, in which even recently daily commuting was one of the most expressed forms of mechanical population development. Daily commuting is seen as an initial state leading to permanent migration, i.e. to out-migration. Potential migrants become familiar with the social, economic, cultural and other traits of their future destination area, which makes it easier for them to leave their places of origin. Thus, for the purposes of the research, the survey selected a population of daily commuters, mainly young people of working age who usually constitute the segment of the population most Iikely to migrate. The survey used both a questionnaire and interviews. Respondents belonged to two relevant groups of the island population: employees commuting each day to work and pupils commuting daily to school. Even though the sample included practically the entire island population with the given migrational and socio-demographic characteristics, the total number of respondents was still too small for the application of standard methods of statistical analysis. In order to gain better insight into the pre-migrational situation on the islands, a few adult islander commuters were added to the group of commuting employees. The goal of the research was to gain an understanding of commuting phenomena in the island micro-society, especially of the migration dilemmas of young islanders. The most frequent variables in the survey were: island/settlement, gender and school. Commuting between the island and mainland is the dominant form of spatial mobility among islanders and constitutes an essential part of their daily life. The most frequent reasons for commuting among islanders are school attendance, going to work, going
Gravitational Waves in Decaying Vacuum Cosmologies
David Alejandro Tamayo Ramirez
2015-01-01
In the present monograph we study in detail the primordial gravitational waves in cosmologies with a decaying vacuum. The decaying vacuum models are an alternative to solve the cosmological constant problem attributing a dynamic to the vacuum energy. The problem of primordial gravitational waves is discussed in the framework of an expanding, flat, spatially homogeneous and isotropic FLRW Universe described by General Relativity theory with decaying vacuum energy density of the type $\\\\Lambda ...
Robot Vacuum Cleaner Personality and Behavior
Hendriks, A.F.M.; Meerbeek, B.W.; Boess, S.; Pauws, S.C.; Sonneveld, M.
2011-01-01
In this paper we report our study on the user experience of robot vacuum cleaner behavior. How do people want to experience this new type of cleaning appliance? Interviews were conducted to elicit a desired robot vacuum cleaner personality. With this knowledge in mind, behavior was designed for a future robot vacuum cleaner. A video prototype was used to evaluate how people experienced the behavior of this robot vacuum cleaner. The results indicate that people recognizedthe intended personali...
Separation of attractors in 1-modulus quantum corrected special geometry
Bellucci, S; Marrani, A; Shcherbakov, A
2008-01-01
We study the solutions to the N=2, d=4 Attractor Equations in a dyonic, extremal, static, spherically symmetric and asymptotically flat black hole background, in the simplest case of perturbative quantum corrected cubic Special Kahler geometry consistent with continuous axion-shift symmetry, namely in the 1-modulus Special Kahler geometry described (in a suitable special symplectic coordinate) by the holomorphic Kahler gauge-invariant prepotential F=t^3+i*lambda, with lambda real. By performing computations in the ``magnetic'' charge configuration, we find evidence for interesting phenomena (absent in the classical limit of vanishing lambda). Namely, for a certain range of the quantum parameter lambda we find a ``splitting'' of attractors, i.e. the existence of multiple solutions to the Attractor Equations for fixed supporting charge configuration. This corresponds to the existence of ``area codes'' in the radial evolution of the scalar t, determined by the various disconnected regions of the moduli space, wh...
DEM interpolation weight calculation modulus based on maximum entropy
Chen, Tian-wei; Yang, Xia
2015-12-01
There is negative-weight in traditional interpolation of gridding DEM, in the article, the principle of Maximum Entropy is utilized to analyze the model system which depends on modulus of space weight. Negative-weight problem of the DEM interpolation is researched via building Maximum Entropy model, and adding nonnegative, first and second order's Moment constraints, the negative-weight problem is solved. The correctness and accuracy of the method was validated with genetic algorithm in matlab program. The method is compared with the method of Yang Chizhong interpolation and quadratic program. Comparison shows that the volume and scaling of Maximum Entropy's weight is fit to relations of space and the accuracy is superior to the latter two.
14 CFR 29.1433 - Vacuum systems.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vacuum systems. 29.1433 Section 29.1433... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment Miscellaneous Equipment § 29.1433 Vacuum systems. (a... the discharge lines from the vacuum air pump when the delivery temperature of the air becomes unsafe...
Utilize Vacuum Forming to Make Interdisciplinary Connections
Love, Tyler S.; Valenza, Frank
2011-01-01
The concept of vacuum forming has been around since the 19th century, despite not being fully utilized in industry until the 1950s. In the past, industrial arts classes have used vacuum-forming projects to concentrate solely on the manufacturing process and the final product. However, vacuum forming is not just an old industrial arts activity; it…
14 CFR 25.1433 - Vacuum systems.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vacuum systems. 25.1433 Section 25.1433... STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment Miscellaneous Equipment § 25.1433 Vacuum systems. There... discharge lines from the vacuum air pump when the delivery temperature of the air becomes unsafe. ...
The Dirac-Electron Vacuum Wave
Directory of Open Access Journals (Sweden)
Daywitt W. C.
2016-07-01
Full Text Available This paper argues that the Dirac equation can be interpreted as an interaction between the electron core and the Planck vacuum state, where the positive and negative solutions represent respectively the dynamics of the electron core and a vacuum wave propagating within the vacuum state. Results show that the nonrelativistic positive solution reduces to the Schrödinger wave equation
Fast Katz and commuters : efficient estimation of social relatedness.
Energy Technology Data Exchange (ETDEWEB)
On, Byung-Won; Lakshmanan, Laks V. S.; Esfandiar, Pooya; Bonchi, Francesco; Grief, Chen; Gleich, David F.
2010-12-01
Motivated by social network data mining problems such as link prediction and collaborative filtering, significant research effort has been devoted to computing topological measures including the Katz score and the commute time. Existing approaches typically approximate all pairwise relationships simultaneously. In this paper, we are interested in computing: the score for a single pair of nodes, and the top-k nodes with the best scores from a given source node. For the pairwise problem, we apply an iterative algorithm that computes upper and lower bounds for the measures we seek. This algorithm exploits a relationship between the Lanczos process and a quadrature rule. For the top-k problem, we propose an algorithm that only accesses a small portion of the graph and is related to techniques used in personalized PageRank computing. To test the scalability and accuracy of our algorithms we experiment with three real-world networks and find that these algorithms run in milliseconds to seconds without any preprocessing.
Fully controlled 5-phase, 10-pulse, line commutated rectifier
Directory of Open Access Journals (Sweden)
Mahmoud I. Masoud
2015-12-01
Full Text Available The development and production of multiphase machines either generators or motors, specially five-phase, offers improved performance compared to three-phase counterpart. Five phase generators could generate power in applications such as, but not limited to, wind power generation, electric vehicles, aerospace, and oil and gas. The five-phase generator output requires converter system such as ac–dc converters. In this paper, a fully controlled 10-pulse line commutated rectifier, suitable to be engaged with wind energy applications, fed from five-phase source is introduced. A shunt active power filter (APF is used to improve power factor and supply current total harmonic distortion (THD. Compared to three-phase converters, 6-pulse or 12-pulse rectifiers, the 10-pulse rectifier engaged with 5-phase source alleviate their drawbacks such as high dc ripples and no need for electric gear or phase shifting transformer. MATLAB/SIMULINK platform is used as a simulation tool to investigate the performance of the proposed rectifier.
Computational quantum-classical boundary of noisy commuting quantum circuits.
Fujii, Keisuke; Tamate, Shuhei
2016-05-18
It is often said that the transition from quantum to classical worlds is caused by decoherence originated from an interaction between a system of interest and its surrounding environment. Here we establish a computational quantum-classical boundary from the viewpoint of classical simulatability of a quantum system under decoherence. Specifically, we consider commuting quantum circuits being subject to decoherence. Or equivalently, we can regard them as measurement-based quantum computation on decohered weighted graph states. To show intractability of classical simulation in the quantum side, we utilize the postselection argument and crucially strengthen it by taking noise effect into account. Classical simulatability in the classical side is also shown constructively by using both separable criteria in a projected-entangled-pair-state picture and the Gottesman-Knill theorem for mixed state Clifford circuits. We found that when each qubit is subject to a single-qubit complete-positive-trace-preserving noise, the computational quantum-classical boundary is sharply given by the noise rate required for the distillability of a magic state. The obtained quantum-classical boundary of noisy quantum dynamics reveals a complexity landscape of controlled quantum systems. This paves a way to an experimentally feasible verification of quantum mechanics in a high complexity limit beyond classically simulatable region.
Analyzing multiday route choice behavior of commuters using GPS data
Directory of Open Access Journals (Sweden)
Wenyun Tang
2016-02-01
Full Text Available In this study, accurate global position system and geographic information system data were employed to reveal multiday routes people used and to study multiday route choice behavior for the same origin–destination trips, from home to work. A new way of thinking about route choice modeling is provided in this study. Travelers are classified into three kinds based on the deviation between actual routes and the shortest travel time paths. Based on the classification, a two-stage route choice process is proposed, in which the first step is to classify the travelers and the second one is to model route choice behavior. After analyzing the characteristics of different types of travelers, an artificial neural network was adopted to classify travelers and model route choice behavior. An empirical study using global position systems data collected in Minneapolis–St Paul metropolitan area was carried out. It finds that most travelers follow the same route during commute trips on successive days. And different types of travelers have a significant difference in route choice property. The modeling results indicate that neural network framework can classify travelers and model route choice well.
Directory of Open Access Journals (Sweden)
Aristophanes Dimakis
2013-02-01
Full Text Available We present a general solution-generating result within the bidifferential calculus approach to integrable partial differential and difference equations, based on a binary Darboux-type transformation. This is then applied to the non-autonomous chiral model, a certain reduction of which is known to appear in the case of the D-dimensional vacuum Einstein equations with D−2 commuting Killing vector fields. A large class of exact solutions is obtained, and the aforementioned reduction is implemented. This results in an alternative to the well-known Belinski-Zakharov formalism. We recover relevant examples of space-times in dimensions four (Kerr-NUT, Tomimatsu-Sato and five (single and double Myers-Perry black holes, black saturn, bicycling black rings.
Advanced window incorporating vacuum glazing
Asano, Osamu; Misonou, Masao; Kato, Hidemi; Nagasaka, Shigeki
1999-10-01
Vacuum glazing product named SPACIATM, being an unique product with very high levels of thermal insulation properties in a very small thickness, is described in detail. The construction and manufacturing process of SPACIATM are reported. Its design, which was originally established by R.E. Collins et al. of the University of Sydney, has been adjusted in order to meet the requirements of the Japanese market and the requirements of mass production process. SPACIATM is found to have several unique features including airborne sound insulation as well as thermal insulation. Energy required for air conditioning was simulated for Japanese houses with various glazings, and it was revealed that SPACIATM could save the energy efficiently. Finally, hybrid IG unit, where vacuum glazing is incorporated into a conventional IG unit, is proposed for further improvement of thermal insulation.
LEP vacuum chamber, early prototype
CERN PhotoLab
1978-01-01
The structure of LEP, with long bending magnets and little access to the vacuum chamber between them, required distributed pumping. This is an early prototype for the LEP vacuum chamber, made from extruded aluminium. The main opening is for the beam. The small channel to the right is for cooling water, to carry away the heat deposited by the synchroton radiation from the beam. The 4 slots in the channel to the left house the strip-shaped ion-getter pumps (see 7810255). The ion-getter pumps depended on the magnetic field of the bending magnets, too low at injection energy for the pumps to function well. Also, a different design was required outside the bending magnets. This design was therefore abandoned, in favour of a thermal getter pump (see 8301153 and 8305170).
Vacuum Alignment with more Flavors
DEFF Research Database (Denmark)
Ryttov, Thomas
2014-01-01
_f=2$ and $N_f=3$ we reproduce earlier known results including the Dashen phase with spontaneous violation of the combined charge conjugation and parity symmetry, CP. For $N_f=4$ we find regions with and without spontaneous CP violation. We then generalize to an arbitrary number of flavors. Here......We study the alignment of the vacuum in gauge theories with $N_f$ Dirac fermions transforming according to a complex representation of the gauge group. The alignment of the vacuum is produced by adding a small mass perturbation to the theory. We study in detail the $N_f=2,3$ and $4$ case. For $N...... it is shown that at the point where $N_f-1$ flavors are degenerate with positive mass $m>0$ and the mass of the $N_f$'th flavor becomes negative and equal to $-m$ CP breaks spontaneously....
Visualizing electromagnetic vacuum by MRI
Chandrashekar, Chandrika S; Chandrashekar, S; Taylor, Erika A; Taylor, Deanne M
2016-01-01
Based upon Maxwell's equations, it has long been established that oscillating electromagnetic (EM) fields incident upon a metal surface decay exponentially inside the conductor, leading to a virtual EM vacuum at sufficient depths. Magnetic resonance imaging (MRI) utilizes radiofrequency (r.f.) EM fields to produce images. Here we present the first visualization of an EM vacuum inside a bulk metal strip by MRI, amongst several novel findings. We uncover unexpected MRI intensity patterns arising from two orthogonal pairs of faces of a metal strip, and derive formulae for their intensity ratios. Further, we furnish chemical shift imaging (CSI) results that discriminate different faces (surfaces) of a metal block according to their distinct nuclear magnetic resonance (NMR) chemical shifts, which holds much promise for monitoring surface chemical reactions noninvasively. Bulk metals are ubiquitous, and MRI is a premier noninvasive diagnostic tool. Combining the two, the emerging field of bulk metal MRI can be expe...
Quantum vacuum and dark matter
Hajdukovic, Dragan Slavkov
2012-01-01
Recently, the gravitational polarization of the quantum vacuum was proposed as alternative to the dark matter paradigm. In the present paper we consider four benchmark measurements: the universality of the central surface density of galaxy dark matter haloes, the cored dark matter haloes in dwarf spheroidal galaxies, the non-existence of dark disks in spiral galaxies and distribution of dark matter after collision of clusters of galaxies (the Bullet cluster is a famous example). Only some of these phenomena (but not all of them) can (in principle) be explained by the dark matter and the theories of modified gravity. However, we argue that the framework of the gravitational polarization of the quantum vacuum allows the understanding of the totality of these phenomena.
2014-01-01
M.Sc. (Environmental Management) This study explores the school-commuting phenomenon that occurs across the city of Johannesburg, with specific reference to inner city private schools. It was hypothesized that the school commute, much of which has its origins in spatial apartheid, is financially and socially unsustainable. As spatial apartheid continues to dominate the urban landscape in Johannesburg, it is posited that overall, the school commute hinders the City of Johannesburg’s progres...
Mass dependence of vacuum energy
Fulling, S. A.
2005-01-01
The regularized vacuum energy (or energy density) of a quantum field subjected to static external conditions is shown to satisfy a certain partial differential equation with respect to two variables, the mass and the "time" (ultraviolet cutoff parameter). The equation is solved to provide integral expressions for the regularized energy (more precisely, the cylinder kernel) at positive mass in terms of that for zero mass. Alternatively, for fixed positive mass all coefficients in the short-tim...
Vacuum configuration for inflationary superstring
Energy Technology Data Exchange (ETDEWEB)
Baadhio, R.A. (Theoretical Physics Group, Physics Division, Lawrence Berkeley Laboratory and Department of Physics, University of California at Berkeley, Berkeley, California 94720 (United States))
1993-02-01
The vacuum configuration for the inflationary superstring theory is established. It is argued that the basic physical contents of the inflationary universe are characterized by the Novikov higher signature. Finally it is shown, with respect to the splitting of Paper II, that the index of the Dirac operator defined in our inflated universe, and in the parallel shadow one, is indeed [ital h]-cobordant.
Entanglement in the Bogoliubov vacuum
DEFF Research Database (Denmark)
Poulsen, Uffe Vestergaard; Meyer, T.; Lewenstein, M.
2005-01-01
We analyze the entanglement properties of the Bogoliubov vacuum, which is obtained as a second-order approximation to the ground state of an interacting Bose-Einstein condensate. We work in one- and two-dimensional lattices and study the entanglement between two groups of sites as a function...... and to be favoured by strong interactions. Conversely, long-range entanglement is favoured by relatively weak interactions. No examples of bound entanglement are found....
Field Emission in Vacuum Microelectronics
Fursey, George; Schwoebel, Paul
2005-01-01
Field emission is a phenomenon described by quantum mechanics. Its emission capability is millions times higher than that of any other known types of electron emission. Nowadays this phenomenon is experiencing a new life due to wonderful applications in the atomic resolution microscopy, in electronic holography, and in the vacuum micro- and nanoelectronics in general. The main field emission properties, and some most remarkable experimental facts and applications, are described in this book.
Oscillations of a polarizable vacuum
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James G. Gilson
1991-01-01
Full Text Available A classical basis for one-dimensional Schrödinger quantum theory is constructed from simple vacuum polarization harmonic oscillators within standard stochastic theory. The model is constructed on a two-dimensional phase configuration surface with phase velocity vectors that have a speed of light zitterbewegung behaviour character. The system supplies a natural Hermitian scalar product describing probability density which is derived from angular momentum considerations. The generality of the model which is extensive is discussed.
Apparent elastic modulus and hysteresis of skeletal muscle cells throughout differentiation
Collinsworth, Amy M.; Zhang, Sarah; Kraus, William E.; Truskey, George A.
2002-01-01
The effect of differentiation on the transverse mechanical properties of mammalian myocytes was determined by using atomic force microscopy. The apparent elastic modulus increased from 11.5 +/- 1.3 kPa for undifferentiated myoblasts to 45.3 +/- 4.0 kPa after 8 days of differentiation (P elastic modulus, but neither myosin nor beta-tubulin were associated with hysteresis. Microtubules did not affect mechanical properties because treatment with colchicine did not alter the apparent elastic modulus or hysteresis. Treatment with cytochalasin D or 2,3-butanedione 2-monoxime led to a significant reduction in the apparent elastic modulus but no change in hysteresis. In summary, skeletal muscle cells exhibited viscoelastic behavior that changed during differentiation, yielding an increase in the transverse elastic modulus. Major contributors to changes in the transverse elastic modulus during differentiation were actin and myosin.
McNab, A.; Stagni, F.; Ubeda Garcia, M.
2014-06-01
We present a model for the operation of computing nodes at a site using Virtual Machines (VMs), in which VMs are created and contextualized for experiments by the site itself. For the experiment, these VMs appear to be produced spontaneously "in the vacuum" rather having to ask the site to create each one. This model takes advantage of the existing pilot job frameworks adopted by many experiments. In the Vacuum model, the contextualization process starts a job agent within the VM and real jobs are fetched from the central task queue as normal. An implementation of the Vacuum scheme, Vac, is presented in which a VM factory runs on each physical worker node to create and contextualize its set of VMs. With this system, each node's VM factory can decide which experiments' VMs to run, based on site-wide target shares and on a peer-to-peer protocol in which the site's VM factories query each other to discover which VM types they are running. A property of this system is that there is no gate keeper service, head node, or batch system accepting and then directing jobs to particular worker nodes, avoiding several central points of failure. Finally, we describe tests of the Vac system using jobs from the central LHCb task queue, using the same contextualization procedure for VMs developed by LHCb for Clouds.
Vacuum electronics applications at CERN
Jensen, E
2009-01-01
CERN operates a large number of vacuum electronics based RF power amplifiers covering a wide frequency range – over 300 sockets with 24 different grid tubes and klystrons are in use and require constant care to insure reliable operation of the accelerators. This is in particular true for the LHC and its injector chain, for which a program of improvement and stepwise upgrade has started. These include IOT’s for the SPS and klystrons and modulators for Linac4 and SPL. The CLIC study and the CTF3 facility are relevant to vacuum electronics in many ways: The CLIC primary RF power, to be provided at 1 GHz, requires highest possible efficiency and phase stability, MBK’s are likely candidates. The CLIC RF power source and CTF3 are themselves large vacuum electronics applications, consequently there are areas of common interest and concern, including fabrication techniques, pulse compression techniques, breakdown and multipactor theory and simulation, material fatigue, numerical analysis of slow-wave structures...
Improved Aerogel Vacuum Thermal Insulation
Ruemmele, Warren P.; Bue, Grant C.
2009-01-01
An improved design concept for aerogel vacuum thermal-insulation panels calls for multiple layers of aerogel sandwiched between layers of aluminized Mylar (or equivalent) poly(ethylene terephthalate), as depicted in the figure. This concept is applicable to both the rigid (brick) form and the flexible (blanket) form of aerogel vacuum thermal-insulation panels. Heretofore, the fabrication of a typical aerogel vacuum insulating panel has involved encapsulation of a single layer of aerogel in poly(ethylene terephthalate) and pumping of gases out of the aerogel-filled volume. A multilayer panel according to the improved design concept is fabricated in basically the same way: Multiple alternating layers of aerogel and aluminized poly(ethylene terephthalate) are assembled, then encapsulated in an outer layer of poly(ethylene terephthalate), and then the volume containing the multilayer structure is evacuated as in the single-layer case. The multilayer concept makes it possible to reduce effective thermal conductivity of a panel below that of a comparable single-layer panel, without adding weight or incurring other performance penalties. Implementation of the multilayer concept is simple and relatively inexpensive, involving only a few additional fabrication steps to assemble the multiple layers prior to evacuation. For a panel of the blanket type, the multilayer concept, affords the additional advantage of reduced stiffness.
Effect of Cyclic Loading on Modulus of Elasticity of Aspen Wood
Milan Gaff; Miroslav Gašparík
2014-01-01
This article investigates the modulus of elasticity of solid and laminated aspen wood of various thicknesses after cyclic loading. A three-point static bending test was carried out to determine the modulus of elasticity. Cyclically loaded samples were compared with samples without cyclic loading. For the laminated wood, the results demonstrated a statistically significant impact of cyclic loading on the elasticity modulus. In contrast, no significant impact of cyclic loading was shown for the...
National Research Council Canada - National Science Library
Adachi, Hiromasa; Hasegawa, Teruo
2005-01-01
For evaluation of thermal endurance in foamed plastics, temperature and time dependence of compression dynamic modulus of four flexible polyurethane foams was investigated by dynamic viscoelastic measurements...
Jiang, Jingfeng; Brace, Chris; Andreano, Anita; DeWall, Ryan J.; Rubert, Nick; Fisher, Ted G.; Varghese, Tomy; Lee, Fred; Hall, Timothy J.
2010-01-01
The feasibility of using ultrasound-based elastic modulus imaging to visualize thermal ablation zones in an in vivo porcine model is reported in this article. Elastic modulus images of soft tissues are estimated as an inverse optimization problem. Ultrasonically-measured displacement data are utilized as inputs to determine an elastic modulus distribution that provides the best match to this displacement field. A total of 14 in vivo thermal ablation zones were investigated in this study. To determine the accuracy of delineation of each thermal ablation zone using elastic modulus imaging, the dimensions (lengths of long and short axes) and the are of each thermal ablation zone obtained from an elastic modulus image was compared to the corresponding gross pathology photograph of the same ablation zone. Comparison of elastic modulus imaging measurements and gross pathology measurements showed high correlation with respect to the area of thermal ablation zones (Pearson coefficient = 0.950 and pelastic modulus imaging can more accurately depict thermal ablation zones, when compared to strain imaging (14.7% versus 22.3% absolute percent error in area measurements, respectively). Furthermore, elastic modulus imaging also provide higher (more than a factor of two) contrast-to-noise ratios for evaluating these thermal ablation zones than those on corresponding strain images, thereby reducing inter-observer variability. Our preliminary results suggest that elastic modulus imaging might potentially enhance the ability to visualize thermal ablation zones, thereby improving assessment of ablative therapies. PMID:20354279
Directory of Open Access Journals (Sweden)
V. I. Djigan
2007-12-01
Full Text Available This paper considers the application of the linear constraints and RLS inverse QR decomposition in adaptive arrays based on constant modulus criterion. The computational procedures of adaptive algorithms are presented. Linearly constrained least squares adaptive arrays, constant modulus adaptive arrays and linearly constrained constant modulus adaptive arrays are compared via simulation. It is demonstrated, that a constant phase shift in the array output signal, caused by desired signal orientation and array weights, is compensated in a simple way in linearly constrained constant modulus adaptive arrays.
Mark Alexander Butler; Joseph Dahlen; Thomas L. Eberhardt; Cristian Montes; Finto Antony; Richard F. Daniels
2017-01-01
Key message Loblolly pine (Pinus taeda) logs can be evaluated using acoustic velocity whereby threshold acoustic velocity values can be set to ensure lumber meets specified mechanical property design values for modulus of elasticity.Â Context...
Directory of Open Access Journals (Sweden)
Bjørkelund Line A
2009-10-01
Full Text Available Abstract Background Studies assessing active commuting to school usually use simple questionnaires, and often is mode of commuting reported with a single questionnaire item only. The purpose of the present study is to report the test-retest reliability of a newly developed comprehensive questionnaire on active commuting to school and work among 6th grade school children and their parents in Norway. Methods A total of 106 pupils and 77 parents completed a questionnaire two times, 14 days apart. The questionnaire consisted of frequency items on how often the participants walk, cycle, go by car and go by public transportation to school (pupils or work (parents. The questionnaire was divided into seasons and to/from school or work in order to cover seasonal and topographic variations. The average number of trips for each mode of commuting was calculated. Then the sample was categorised into mode of commuting: walkers, cyclists, car commuters or public transport commuters. Results The average numbers of trips did not differ for any of the commuting modes comparing test to retest data for any of the seasons. Test-retest correlation coefficients were high for all modes of commuting (Spearman correlation coefficient were 0.85-0.92 for pupils and 0.82-0.95 for parents. Most participants categorised into mode of commuting were categorized into the same mode at both time points (97% and 95% for pupils and parents respectively. Conclusion This newly developed questionnaire appears to be a reliable tool for measuring active commuting to school and work.
Antony Finto; Lewis Jordan; Laurence R. Schimleck; Alexander Clark; Ray A. Souter; Richard F. Daniels
2011-01-01
Modulus of elasticity (MOE), modulus of rupture (MOR), and specific gravity (SG) are important properties for determining the end-use and value of a piece of lumber. This study addressed the variation in MOE, MOR, and SG with physiographic region, tree height, and wood type. Properties were measured from two static bending samples (dimensions 25.4 mm Ã 25.4 mm Ã 406.4...
Short Exon Detection via Wavelet Transform Modulus Maxima.
Zhang, Xiaolei; Shen, Zhiwei; Zhang, Guishan; Shen, Yuanyu; Chen, Miaomiao; Zhao, Jiaxiang; Wu, Renhua
2016-01-01
The detection of short exons is a challenging open problem in the field of bioinformatics. Due to the fact that the weakness of existing model-independent methods lies in their inability to reliably detect small exons, a model-independent method based on the singularity detection with wavelet transform modulus maxima has been developed for detecting short coding sequences (exons) in eukaryotic DNA sequences. In the analysis of our method, the local maxima can capture and characterize singularities of short exons, which helps to yield significant patterns that are rarely observed with the traditional methods. In order to get some information about singularities on the differences between the exon signal and the background noise, the noise level is estimated by filtering the genomic sequence through a notch filter. Meanwhile, a fast method based on a piecewise cubic Hermite interpolating polynomial is applied to reconstruct the wavelet coefficients for improving the computational efficiency. In addition, the output measure of a paired-numerical representation calculated in both forward and reverse directions is used to incorporate a useful DNA structural property. The performances of our approach and other techniques are evaluated on two benchmark data sets. Experimental results demonstrate that the proposed method outperforms all assessed model-independent methods for detecting short exons in terms of evaluation metrics.
Short Exon Detection via Wavelet Transform Modulus Maxima.
Directory of Open Access Journals (Sweden)
Xiaolei Zhang
Full Text Available The detection of short exons is a challenging open problem in the field of bioinformatics. Due to the fact that the weakness of existing model-independent methods lies in their inability to reliably detect small exons, a model-independent method based on the singularity detection with wavelet transform modulus maxima has been developed for detecting short coding sequences (exons in eukaryotic DNA sequences. In the analysis of our method, the local maxima can capture and characterize singularities of short exons, which helps to yield significant patterns that are rarely observed with the traditional methods. In order to get some information about singularities on the differences between the exon signal and the background noise, the noise level is estimated by filtering the genomic sequence through a notch filter. Meanwhile, a fast method based on a piecewise cubic Hermite interpolating polynomial is applied to reconstruct the wavelet coefficients for improving the computational efficiency. In addition, the output measure of a paired-numerical representation calculated in both forward and reverse directions is used to incorporate a useful DNA structural property. The performances of our approach and other techniques are evaluated on two benchmark data sets. Experimental results demonstrate that the proposed method outperforms all assessed model-independent methods for detecting short exons in terms of evaluation metrics.
Polymerization Shrinkage and Flexural Modulus of Flowable Dental Composites
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Janaína Cavalcanti Xavier
2010-09-01
Full Text Available Linear polymerization shrinkage (LPS, flexural strength (FS and modulus of elasticity (ME of low-viscosity resin composites (Admira Flow™, Grandio Flow™/VOCO; Filtek Z350 Flow™/3M ESPE; Tetric Flow™/Ivoclar-Vivadent was evaluated using a well-established conventional micro-hybrid composite as a standard (Filtek Z250™/3M ESPE. For the measurement of LPS, composites were applied to a cylindrical metallic mould and polymerized (n = 8. The gap formed at the resin/mould interface was observed using SEM (1500×. For FS and ME, specimens were prepared according to the ISO 4049 specifications (n = 10. Statistical analysis of the data was performed with one-way ANOVA and the Tukey test. The conventional resin presented significantly lower LPS associated with high FS and ME, but only the ME values of the conventional resin differed significantly from the low-viscosity composites. The relationship between ME and LPS of low-viscosity resin composites when used as restorative material is a critical factor in contraction stress relief and marginal leakage.
Expression, crosslinking, and developing modulus master curves of recombinant resilin.
Khandaker, Md Shahriar K; Dudek, Daniel M; Beers, Eric P; Dillard, David A
2017-05-01
Resilin is a disordered elastomeric protein found in specialized regions of insect cuticles, where low stiffness and high resilience are required. Having a wide range of functions that vary among insect species, resilin operates across a wide frequency range, from 5Hz for locomotion to 13kHz for sound production. We synthesize and crosslink a recombinant resilin from clone-1 (exon-1+exon-2) of the gene, and determine the water content (approximately 80wt%) and dynamic mechanical properties, along with estimating surface energies relevant for adhesion. Dynamic moduli master curves have been developed, by applying the time-temperature superposition principle (TTSP) and time-temperature concentration superposition principle (TTCSP), and compared with reported master curves for natural resilin from locusts, dragonflies, and cockroaches. To our knowledge, this is the first time dynamic moduli master curves have been developed to explore the dynamic mechanical properties of recombinant resilin and compare with resilin behavior. The resulting master curves show that the synthetic resilin undergoes a pronounced transition with increasing ethanol concentrations, with the storage modulus increasing by approximately three orders of magnitude. Although possibly a glass transition, alternate explanations include the formation of intramolecular hydrogen bonds or that the chitin binding domain (ChBD) in exon-2 might change the secondary structure of the normally disordered exon-1 into more ordered conformations that limit deformation. Copyright © 2017 Elsevier Ltd. All rights reserved.
Toeplitz Quantization for Non-commutating Symbol Spaces such as SUq(2
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Sontz Stephen Bruce
2016-08-01
Full Text Available Toeplitz quantization is defined in a general setting in which the symbols are the elements of a possibly non-commutative algebra with a conjugation and a possibly degenerate inner product. We show that the quantum group SUq(2 is such an algebra. Unlike many quantization schemes, this Toeplitz quantization does not require a measure. The theory is based on the mathematical structures defined and studied in several recent papers of the author; those papers dealt with some specific examples of this new Toeplitz quantization. Annihilation and creation operators are defined as densely defined Toeplitz operators acting in a quantum Hilbert space, and their commutation relations are discussed. At this point Planck’s constant is introduced into the theory. Due to the possibility of non-commuting symbols, there are now two definitions for anti-Wick quantization; these two definitions are equivalent in the commutative case. The Toeplitz quantization introduced here satisfies one of these definitions, but not necessarily the other. This theory should be considered as a second quantization, since it quantizes non-commutative (that is, already quantum objects. The quantization theory presented here has two essential features of a physically useful quantization: Planck’s constant and a Hilbert space where natural, densely defined operators act.
Pilot age and geographic region of commuter and air taxi crashes: a case-control study.
Rebok, George W; Qiang, Yandong; Baker, Susan P; Li, Guohua
2011-02-01
Previous studies of major airline and general aviation crashes have identified a host of risk factors. We examined risk factors related to crashes involving commuter air carrier and air taxi flights. A matched case-control design was applied to assess the association of pilot age, total flight time, and geographic region with commuter air carrier and air taxi crashes (14 CFR Part 135) from 1983-2002 in the United States. A total of 2033 commuter air carrier or air taxi crashes from the National Transportation Safety Board aviation crash database were identified as eligible cases. Controls were randomly selected incidents from the Federal Aviation Administration's (FAA) aviation incident database coded under Part 135 operation. Relative to controls, commuter air carrier and air taxi crashes were less likely to occur in pilots under 30 yr of age (adjusted odds ratio 0.68, 95% confidence interval 0.54-0.88) after adjusting for geographic region and total flight time. With adjustment for pilot age and total flight time, the commuter air carrier and air taxi crashes with pilot error were nearly 13 times as likely to be in Alaska as their matched controls (adjusted odds ratio 12.84, 95% confidence interval 5.24-31.45). These results suggest that pilot age may be associated with risk of crash involvement in Part 135 operations. The excess crash risk in Alaska with or without pilot error underscores the importance of environmental hazards in flight safety.
Effect of a School Choice Policy Change on Active Commuting to Elementary School.
Sirard, John R; McDonald, Kelsey; Mustain, Patrick; Hogan, Whitney; Helm, Alison
2015-01-01
The purposes of this study were to assess the effect of restricting school choice on changes in travel distance to school and transportation mode for elementary school students. Study design was pre-post (spring 2010-fall 2010) quasi-experimental. Study setting was all public elementary schools in Minneapolis, Minnesota. Subjects comprised approximately 20,500 students across 39 schools. Study assessed a school choice policy change that restricted school choice to a school closer to the family's home. School district transportation data were used to determine distance to school. Direct observations of student travel modes (two morning and two afternoon commutes at each time point) were used to assess transportation mode. Chi-square and independent-sample t-tests were calculated to describe the schools. Repeated measures general linear models were used to assess changes in travel distance to school and observed commuting behavior. Distance to school significantly decreased (1.83 ± .48 miles to 1.74 ± .46 miles; p = .002). We failed to observe any significant changes in morning (+.7%) or afternoon (-.7%) active commuting (both p = .08) or the number of automobiles in the morning (-7 autos per school; p = .06) or afternoon (+3 autos per school; p = .14). The more restrictive school choice policy decreased distance to school but had no significant effect on active commuting. Policy interventions designed to increase active commuting to school may require additional time to gain traction and programmatic support to induce changes in behavior.
García-Hermoso, Antonio; Saavedra, Jose M; Olloquequi, Jordi; Ramírez-Vélez, Robinson
2017-04-04
Habitual active commuting to school may be positively associated with academic achievement. The aim of this study was to examine the relationship between duration of walking or otherwise actively commuting to school and academic achievement. This cross-sectional study included 389 adolescents from seven rural schools (12-13 years). Mode and duration of active commuting to school (use of active means such as walking or biking to and from school) and screen time were self-reported. Academic achievement was determined by the outcome in basic grades (language and mathematics). Active commuting to school was not associated with higher scores in any grades after adjustment for potential confounders. No evidence was found of interactions between gender and academic achievement, but there was interaction with duration of walking (60 min). Adjusted binary logistic regression analysis suggested that adolescents who spent between 30 and 60 min actively commuting were more likely to obtain high academic achievement (language and mathematics). Thirty to 60 min of ACS may have a positive influence on academic achievement in adolescents, so, it is necessary to make recommendations for the children to walk from and/or to school. This could help society to recognize the relevance of physical activity to health as well as to academic performance.
Vacuum Chambers for LEP sections
1983-01-01
The picture shows sections of the LEP vacuum chambers to be installed in the dipole magnets (left) and in the quadrupoles (right). The dipole chamber has three channels: the beam chamber, the pumping duct where the NEG (non-evaporabe getter) is installed and the water channel for cooling (on top in the picture). The pumping duct is connected to the beam chamber through holes in the separating wall. The thick lead lining to shield radiation can also be seen. These chambers were manufactured as extruded aluminium alloy profiles.
Reimers, Harold; Andampour, Jay; Kunitser, Craig; Thomas, Ike
1995-01-01
Vacuum cleaner collects and retains dust, wet debris, and liquids. Designed for housekeeping on Space Station Freedom, it functions equally well in normal Earth Gravity or in microgravity. Generates acoustic noise at comfortably low levels and includes circuitry that reduces electromagnetic interference to other electronic equipment. Draws materials into bag made of hydrophobic sheet with layers of hydrophilic super-absorbing pads at downstream end material. Hydrophilic material can gel many times its own weight of liquid. Blower also provides secondary airflow to cool its electronic components.
Congestion Behavior under Uncertainty on Morning Commute with Preferred Arrival Time Interval
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LingLing Xiao
2014-01-01
Full Text Available This paper extends the bottleneck model to study congestion behavior of morning commute with flexible work schedule. The proposed model assumes a stochastic bottleneck capacity which follows a uniform distribution and homogeneous commuters who have the same preferred arrival time interval. The commuters are fully aware of the stochastic properties of travel time and schedule delay distributions at all departure times that emerge from day-to-day capacity variations. The commuters’ departure time choice follows user equilibrium (UE principle in terms of the expected trip cost. Analytical and numerical solutions of this model are provided. The equilibrium departure time patterns are examined which show that the stochastic capacity increases the mean trip cost and lengthens the rush hour. The adoption of flexitime results in less congestion and more efficient use of bottleneck capacity than fixed-time work schedule. The longer the flexi-time interval is, the more uniformly distributed the departure times are.
PASSENGER CAR USAGE FOR COMMUTING TO WORK AS A FUNCTION OF LIMITED STAY AT CAR PARKS
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Valentina Basarić
2013-07-01
Full Text Available The analysis of the experiences in European cities, following the implementation of different transport policy measures, has led to a conclusion that parking policy measures have the dominant effect on the choice of private car as a mode of transport. This effect is the greatest for the commutes to work, characterized by the longest duration of parking space occupancy. Given the aforementioned experiences in developed European cities, the main aim of the study presented here was the determination of a relationship between limiting the duration of parking space occupancy in the Novi Sad city centre and the transport participants’ decision whether or not to use passenger car to commute to work. Based on the established interdependence between these parameters, we developed a mathematical model for calculating a number of expected car (commuting journeys that terminate in the city centre as a function of limited duration of parking space occupancy.
Effectiveness and implementation of interventions to increase commuter cycling to school
DEFF Research Database (Denmark)
Østergaard, Lars; Støckel, Jan Toftegaard; Andersen, Lars Bo
2015-01-01
BACKGROUND: Active transportation to school has been positively associated with various health parameters whereas only sparse evidence exists on risk of injury while commuting to school. This study investigated the overall effectiveness of cycling promotion combined with structural changes...... = 12) or intervention schools (n = 13). All children (n = 2415) from the 4(th) and 5(th) grade were measured at baseline during spring 2010 and at follow-up one year later. RESULTS: No significant differences in commuter cycling were detected in the adjusted analyses comparing the intervention...... on cycling to school. METHODS: Interventions at public schools in three different regions in Denmark were based on planned infrastructural changes near schools (e.g. road surface and traffic regulation) and school-motivation for promoting commuter cycling. Participants were pupils from control schools (n...
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Bolsinov Alexey V.
2016-01-01
Full Text Available The Mishchenko-Fomenko conjecture says that for each real or complex finite-dimensional Lie algebra g there exists a complete set of commuting polynomials on its dual space g*. In terms of the theory of integrable Hamiltonian systems this means that the dual space g* endowed with the standard Lie-Poisson bracket admits polynomial integrable Hamiltonian systems. This conjecture was proved by S. T. Sadetov in 2003. Following his idea, we give an explicit geometric construction for commuting polynomials on g* and consider some examples. (This text is a revised version of my paper published in Russian: A. V. Bolsinov, Complete commutative families of polynomials in Poisson–Lie algebras: A proof of the Mischenko–Fomenko conjecture in book: Tensor and Vector Analysis, Vol. 26, Moscow State University, 2005, 87–109.
Roadside observation of secondary school students' commuting to school in Vientiane, Laos.
Ichikawa, Masao; Nakahara, Shinji; Phommachanh, Sysavanh; Mayxay, Mayfong; Kimura, Akio
2015-01-01
To investigate modes of secondary school students' commuting to school and their unsafe driving practices in Laos, we conducted a roadside observation in front of the gate of a selected school in central Vientiane in December 2011. Of the 544 students observed, the majority came to school on foot (43%), followed by motorcycle (36%), and bicycle (14%). Of the 195 students who commuted by motorcycle, 45 (23%) drove it themselves. Of the 150 students who commuted as pillion riders, 35 (23%) were driven by a student or another child driver. The prevalence of helmet use among students (3%) was much lower than adults (66%). It was common for adult drivers to wear a helmet but to leave student pillion riders unhelmeted on the same motorcycle. Carrying two or three pillion riders was also often observed. The study revealed the necessity for measures to promote safe travel to school.
Commuting to work: RN travel time to employment in rural and urban areas.
Rosenberg, Marie-Claire; Corcoran, Sean P; Kovner, Christine; Brewer, Carol
2011-02-01
To investigate the variation in average daily travel time to work among registered nurses (RNs) living in urban, suburban, and rural areas. We examine how travel time varies across RN characteristics, job setting, and availability of local employment opportunities. Descriptive statistics and linear regression using a 5% sample from the 2000 Census and a longitudinal survey of newly licensed RNs (NLRN). Travel time for NLRN respondents was estimated using geographic information systems (GIS) software. In the NLRN, rural nurses and those living in small towns had significantly longer average commute times. Young married RNs and RNs with children also tended to have longer commute times, as did RNs employed by hospitals. The findings indicate that travel time to work varies significantly across locale types. Further research is needed to understand whether and to what extent lengthy commute times impact RN workforce needs in rural and urban areas.
The Association between Access to Public Transportation and Self-Reported Active Commuting
DEFF Research Database (Denmark)
Djurhuus, Sune; Hansen, Henning S; Aadahl, Mette
2014-01-01
and self-reported active commuting. Self-reported time spent either walking or cycling commuting each day and the distance to workplace were obtained for adults aged 16 to 65 in the Danish National Health Survey 2010 (n = 28,928). Access to public transportation measures were computed by combining GIS...... more moderate physical activity than non-users. Understanding how public transportation characteristics are associated with active transportation is thus important from a public health perspective. This study examines the associations between objective measures of access to public transportation......-based road network distances from home address to public transit stops an integrating their service level. Multilevel logistic regression was used to examine the association between access to public transportation measures and active commuting. Distance to bus stop, density of bus stops, and number...
Mirone, Giuseppe; Marton, B.; Marton, Beáta; Vancso, Gyula J.
2004-01-01
The temporal development of the modulus of elasticity and its profile were studied in water-borne alkyd coatings during the drying process of the coating films. Values of the Young’s moduli of elasticity of free coating films were measured using tensile tests. Since the elastic modulus is related to
Variation of Hardness and Modulus across thickness of Zr-Cu-Al Metallic Glass Ribbons
Z. Humberto Melgarejo; J.E. Jakes; J. Hwang; Y.E. Kalay; M.J. Kramer; P.M. Voyles; D.S. Stone
2012-01-01
We investigate through-thickness hardness and modulus of Zr50Cu45Al5 metallic glass melt-spun ribbon. Because of their thinness, the ribbons are challenging to measure, so we employ a novel nanoindentation based-method to remove artifacts caused by ribbon flexing and edge effects. Hardness and modulus...
Estimation of the Young’s modulus of cellulose Iß by MM3 and quantum mechanics
Young’s modulus provides a measure of the resistance to deformation of an elastic material. In this study, modulus estimations for models of cellulose Iß relied on calculations performed with molecular mechanics (MM) and quantum mechanics (QM) programs. MM computations used the second generation emp...
A simple model for calculating the bulk modulus of the mixed ionic ...
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 77; Issue 4. A simple model for calculating the bulk modulus of the mixed ionic ... in terms of the bulk modulus of the end members alone. The calculated values are comparable to those deduced from the three-body potential model (TDPM) by applying Vegard's law.
Resilient modulus characteristics of soil subgrade with geopolymer additive in peat
Zain, Nasuhi; Hadiwardoyo, Sigit Pranowo; Rahayu, Wiwik
2017-06-01
Resilient modulus characteristics of peat soil are generally very low with high potential of deformation and low bearing capacity. The efforts to improve the peat subgrade resilient modulus characteristics is required, one among them is by adding the geopolymer additive. Geopolymer was made as an alternative to replace portland cement binder in the concrete mix in order to promote environmentally friendly, low shrinkage value, low creep value, and fire resistant material. The use of geopolymer to improve the mechanical properties of peat as a road construction subgrade, hence it becomes important to identify the effect of geopolymer addition on the resilient modulus characteristics of peat soil. This study investigated the addition of 0% - 20% geopolymer content on peat soil derived from Ogan Komering Ilir, South Sumatera Province. Resilient modulus measurement was performed by using cyclic triaxial test to determine the resilience modulus model as a function of deviator stresses and radial stresses. The test results showed that an increase in radial stresses did not necessarily lead to an increase in modulus resilient, and on the contrary, an increase in deviator stresses led to a decrease in modulus resilient. The addition of geopolymer in peat soil provided an insignificant effect on the increase of resilient modulus value.
Approximation of classes of functions defined by a generalized $r$-th modulus of smoothness
Potapov, Mikhail K.; Berisha, Faton M.
2012-01-01
In this paper, a $k$-th generalized modulus of smoothness is defined based on an asymmetric operator of generalized translation and a theorem is proved about the coincidence of class of functions defined by this modulus and a class of functions having given order of best approximation by algebraic polynomials.
Thin-wall vacuum domain evolution
Directory of Open Access Journals (Sweden)
V.A. Berezin
1983-01-01
Full Text Available In the framework of general relativity the equation of motion of a thin-wall vacuum shell is derived at arbitrary values of the vacuum parameters inside and outside the shell. We obtain that the velocity of the walls of the true vacuum bubble at its expansion does not tend to the velocity of light. We find that vacuum shells could exist now in the universe, which do not contradict to observational cosmology. The types of black holes created are investigated. Restrictions on the mass of the black holes formed from remnants of the false vacuum and on the fraction of the vacuum energy pumped into such black holes are obtained.
A new vacuum for Loop Quantum Gravity
Dittrich, Bianca
2014-01-01
We construct a new vacuum for loop quantum gravity, which is dual to the Ashtekar-Lewandowski vacuum. Because it is based on BF theory, this new vacuum is physical for $(2+1)$-dimensional gravity, and much closer to the spirit of spin foam quantization in general. To construct this new vacuum and the associated representation of quantum observables, we introduce a modified holonomy-flux algebra which is cylindrically consistent with respect to the notion of refinement by time evolution suggested in [1]. This supports the proposal for a construction of a physical vacuum made in [1,2], also for $(3+1)$-dimensional gravity. We expect that the vacuum introduced here will facilitate the extraction of large scale physics and cosmological predictions from loop quantum gravity.
Vacuum systems for the ILC helical undulator
Malyshev, O B; Clarke, J A; Bailey, I R; Dainton, J B; Malysheva, L I; Barber, D P; Cooke, P; Baynham, E; Bradshaw, T; Brummitt, A; Carr, S; Ivanyushenkov, Y; Rochford, J; Moortgat-Pick, G A
2007-01-01
The International Linear Collider (ILC) positron source uses a helical undulator to generate polarized photons of ∼10MeV∼10MeV at the first harmonic. Unlike many undulators used in synchrotron radiation sources, the ILC helical undulator vacuum chamber will be bombarded by photons, generated by the undulator, with energies mostly below that of the first harmonic. Achieving the vacuum specification of ∼100nTorr∼100nTorr in a narrow chamber of 4–6mm4–6mm inner diameter, with a long length of 100–200m100–200m, makes the design of the vacuum system challenging. This article describes the vacuum specifications and calculations of the flux and energy of photons irradiating the undulator vacuum chamber and considers possible vacuum system design solutions for two cases: cryogenic and room temperature.