Pulsed power drivers for ICF and high energy density physics

International Nuclear Information System (INIS)

Ramirez, J.J.; Matzen, M.K.; McDaniel, D.H.

1995-01-01

Nanosecond Pulsed Power Science and Technology has its origins in the 1960s and over the past decade has matured into a flexible and robust discipline capable of addressing key physics issues of importance to ICF and high Energy Density Physics. The major leverage provided by pulsed power is its ability to generate and deliver high energy and high power at low cost and high efficiency. A low-cost, high-efficiency driver is important because of the very large capital investment required for multi-megajoule ignition-class systems. High efficiency is of additional importance for a commercially viable inertial fusion energy option. Nanosecond pulsed power has been aggressively and successfully developed at Sandia over the past twenty years. This effort has led to the development of unique multi-purpose facilities supported by highly capable diagnostic, calculational and analytic capabilities. The Sandia Particle-beam Fusion Program has evolved as part of an integrated national ICF Program. It applies the low-cost, high-efficiency leverage provided by nanosecond pulsed power systems to the longer-term goals of the national program, i.e., the Laboratory Microfusion Facility and Inertial Fusion Energy. A separate effort has led to the application of nanosecond pulsed power to the generation of intense, high-energy laboratory x-ray sources for application to x-ray laser and radiation effects science research. Saturn is the most powerful of these sources to date. It generates ∼500 kilojoules of x-rays from a magnetically driven implosion (Z-pinch). This paper describes results of x-ray physics experiments performed on Saturn, plans for a new Z-pinch drive capability for PBFA-II, and a design concept for the proposed ∼15 MJ Jupiter facility. The opportunities for ICF-relevant research using these facilities will also be discussed

Particle accelerator physics and technology for high energy density physics research

Energy Technology Data Exchange (ETDEWEB)

Hoffmann, D.H.H.; Blazevic, A.; Rosmej, O.N.; Spiller, P.; Tahir, N.A.; Weyrich, K. [Gesellschaft fur Schwerionenforschung, GSI-Darmstadt, Plasmaphysik, Darmstadt (Germany); Hoffmann, D.H.H.; Dafni, T.; Kuster, M.; Ni, P.; Roth, M.; Udrea, S.; Varentsov, D. [Darmstadt Univ., Institut fur Kernphysik, Technische Schlobgartenstr. 9 (Germany); Jacoby, J. [Frankfurt Univ., Institut fur Angewandte Physik (Germany); Kain, V.; Schmidt, R.; Zioutas, K. [European Organization for Nuclear Research (CERN), Geneve (Switzerland); Zioutas, K. [Patras Univ., Dept. of Physics (Greece); Mintsev, V.; Fortov, V.E. [Russian Academy of Sciences, Institute of Problems of Chemical Physics, Chernogolovka (Russian Federation); Sharkov, B.Y. [Institut for Theoretical and Experimental Physics ITEP, Moscow (Russian Federation)

2007-08-15

Interaction phenomena of intense ion- and laser radiation with matter have a large range of application in different fields of science, extending from basic research of plasma properties to applications in energy science, especially in inertial fusion. The heavy ion synchrotron at GSI now routinely delivers intense uranium beams that deposit about 1 kJ/g of specific energy in solid matter, e.g. solid lead. Our simulations show that the new accelerator complex FAIR (Facility for Antiproton and Ion Research) at GSI as well as beams from the CERN large hadron collider (LHC) will vastly extend the accessible parameter range for high energy density states. A natural example of hot dense plasma is provided by our neighbouring star the sun, and allows a deep insight into the physics of fusion, the properties of matter at high energy density, and is moreover an excellent laboratory for astro-particle physics. As such the sun's interior plasma can even be used to probe the existence of novel particles and dark matter candidates. We present an overview on recent results and developments of dense plasma physics addressed with heavy ion and laser beams combined with accelerator- and nuclear physics technology. (authors)

High-energy-density physics foundation of inertial fusion and experimental astrophysics

CERN Document Server

Drake, R Paul

2018-01-01

The raw numbers of high-energy-density physics are amazing: shock waves at hundreds of km/s (approaching a million km per hour), temperatures of millions of degrees, and pressures that exceed 100 million atmospheres. This title surveys the production of high-energy-density conditions, the fundamental plasma and hydrodynamic models that can describe them and the problem of scaling from the laboratory to the cosmos. Connections to astrophysics are discussed throughout. The book is intended to support coursework in high-energy-density physics, to meet the needs of new researchers in this field, and also to serve as a useful reference on the fundamentals. Specifically the book has been designed to enable academics in physics, astrophysics, applied physics and engineering departments to provide in a single-course, an introduction to fluid mechanics and radiative transfer, with dramatic applications in the field of high-energy-density systems. This second edition includes pedagogic improvements to the presentation ...

Propulsion Physics Using the Chameleon Density Model

Science.gov (United States)

Robertson, Glen A.

2011-01-01

To grow as a space faring race, future spaceflight systems will require a new theory of propulsion. Specifically one that does not require mass ejection without limiting the high thrust necessary to accelerate within or beyond our solar system and return within a normal work period or lifetime. The Chameleon Density Model (CDM) is one such model that could provide new paths in propulsion toward this end. The CDM is based on Chameleon Cosmology a dark matter theory; introduced by Khrouy and Weltman in 2004. Chameleon as it is hidden within known physics, where the Chameleon field represents a scalar field within and about an object; even in the vacuum. The CDM relates to density changes in the Chameleon field, where the density changes are related to matter accelerations within and about an object. These density changes in turn change how an object couples to its environment. Whereby, thrust is achieved by causing a differential in the environmental coupling about an object. As a demonstration to show that the CDM fits within known propulsion physics, this paper uses the model to estimate the thrust from a solid rocket motor. Under the CDM, a solid rocket constitutes a two body system, i.e., the changing density of the rocket and the changing density in the nozzle arising from the accelerated mass. Whereby, the interactions between these systems cause a differential coupling to the local gravity environment of the earth. It is shown that the resulting differential in coupling produces a calculated value for the thrust near equivalent to the conventional thrust model used in Sutton and Ross, Rocket Propulsion Elements. Even though imbedded in the equations are the Universe energy scale factor, the reduced Planck mass and the Planck length, which relates the large Universe scale to the subatomic scale.

The trans-generational impact of population density signals on host-parasite interactions.

Science.gov (United States)

Michel, Jessica; Ebert, Dieter; Hall, Matthew D

2016-11-25

The density of a host population is a key parameter underlying disease transmission, but it also has implications for the expression of disease through its effect on host physiology. In response to higher densities, individuals are predicted to either increase their immune investment in response to the elevated risk of parasitism, or conversely to decrease their immune capacity as a consequence of the stress of a crowded environment. However, an individual's health is shaped by many different factors, including their genetic background, current environmental conditions, and maternal effects. Indeed, population density is often sensed through the presence of info-chemicals in the environment, which may influence a host's interaction with parasites, and also those of its offspring. All of which may alter the expression of disease, and potentially uncouple the presumed link between changes in host density and disease outcomes. In this study, we used the water flea Daphnia magna and its obligate bacterial parasite Pasteuria ramosa, to investigate how signals of high host density impact on host-parasite interactions over two consecutive generations. We found that the chemical signals from crowded treatments induced phenotypic changes in both the parental and offspring generations. In the absence of a pathogen, life-history changes were genotype-specific, but consistent across generations, even when the signal of density was removed. In contrast, the influence of density on infected animals depended on the trait and generation of exposure. When directly exposed to signals of high-density, host genotypes responded differently in how they minimised the severity of disease. Yet, in the subsequent generation, the influence of density was rarely genotype-specific and instead related to ability of the host to minimise the onset of infection. Our findings reveal that population level correlations between host density and infection capture only part of the complex relationship

Physics of radiation-driven islands near the tokamak density limit

International Nuclear Information System (INIS)

Gates, D.A.; Delgado-Aparicio, L.; White, R.B.

2013-01-01

In previous work (Gates and Delgado-Aparicio 2012 Phys. Rev. Lett. 108 165004), the onset criterion for radiation-driven islands (Rebut et al 1985 Proc. 10th Int. Conf. on Plasma Physics and Controlled Nuclear Fusion Research 1984 (London, UK, 1984) vol 2 (Vienna: IAEA) p 197) in combination with a simple cylindrical model of tokamak current channel behaviour was shown to be consistent with the empirical scaling of the tokamak density limit (Greenwald et al 1988 Nucl. Fusion 28 2199). A number of the unexplained phenomena at the density limit are consistent with this novel physics mechanism. In this work, a more formal theoretical underpinning, consistent with cylindrical tearing mode theory, is developed for the onset criteria of these modes. The appropriate derivation of the radiation-driven addition to the modified Rutherford equation (MRE) is discussed. Additionally, the ordering of the terms in the MRE is examined in a regime near the density limit. It is hoped that, given the apparent success of this simple model in explaining the observed global scalings, it will lead to a more comprehensive analysis of the possibility that radiation-driven islands are the physics mechanism responsible for the density limit. In particular, with modern diagnostic capabilities detailed measurements of current densities, electron densities and impurity concentrations at rational surfaces should be possible, enabling verification of the concepts described above. (paper)

BONE MINERAL DENSITY IN PHYSICALLY ACTIVE WOMEN ASSESSED BY ULTRASOUND DESINTOMETRY

Directory of Open Access Journals (Sweden)

Ana Marijanac

2015-05-01

Full Text Available Osteoporosis is a disease characterized by low bone mass and density. Physical activity has a positive effect on bone tissue, and it is recommended to prevent bone loss which comes with age. Methods: In purpose of determining bone mineral density in women who are physically active we examined 35 women divided into two groups – subjects who are premenopausal (n=20, 43.52 ± 7.56 years, and subjects who are postmenopausal (n=15, 55.89 ± 5.48. The subjects exercised Pilates method twice a week for one hour. Bone mineral density measurements were done by ultrasound densitometer „Sahara“ through the calcaneus. We get the data of the estimated bone density and T-score for right and left foot separate. Results: According to results premenopausal women have normal bone density, and postmenopausal values represent osteopenia, according to the WHO. There is no subjects who established osteoporosis. Discussion: Previous investigations have confirmed that physical activity is important for the preservation of the bone quality. Increasing steps, using simple everyday tasks, can prevent decrease in BMD in postmenopausal women (Muir et al., 2013, Ashe et al, 2008. There’s difference in the density of the calcaneus between physically active and those who are not, measured by ultrasound densitometry (Vainionpää et al, 2005. We use quantitative ultrasound densitometry to describe BMI of women who exercise Pilates and support the finding that physical activity is one of the ways that may prevent the BMD loss. These research was done as a part of long-term project entitled „Impact of physical activity of the working population“ which is co-financed by Provincial Secretariat for Science and Technological Development.

Wave Generation in Physical Models

DEFF Research Database (Denmark)

Andersen, Thomas Lykke; Frigaard, Peter

The present book describes the most important aspects of wave generation techniques in physical models. Moreover, the book serves as technical documentation for the wave generation software AwaSys 6, cf. Aalborg University (2012). In addition to the two main authors also Tue Hald and Michael...

Perspectives on High-Energy-Density Physics

Science.gov (United States)

Drake, R. Paul

2008-11-01

Much of 21st century plasma physics will involve work to produce, understand, control, and exploit very non-traditional plasmas. High-energy density (HED) plasmas are often examples, variously involving strong Coulomb interactions and few particles per Debeye sphere, dominant radiation effects, strongly relativistic effects, or strongly quantum-mechanical behavior. Indeed, these and other modern plasma systems often fall outside the early standard theoretical definitions of ``plasma''. This presentation will focus on two types of HED plasmas that exhibit non-traditional behavior. Our first example will be the plasmas produced by extremely strong shock waves. Shock waves are present across the entire realm of plasma densities, often in space or astrophysical contexts. HED shock waves (at pressures > 1 Mbar) enable studies in many areas, from equations of state to hydrodynamics to radiation hydrodynamics. We will specifically consider strongly radiative shocks, in which the radiative energy fluxes are comparable to the mechanical energy fluxes that drive the shocks. Modern HED facilities can produce such shocks, which are also present in dense, energetic, astrophysical systems such as supernovae. These shocks are also excellent targets for advanced simulations due to their range of spatial scales and complex radiation transport. Our second example will be relativistic plasmas. In general, these vary from plasmas containing relativistic particle beams, produced for some decades in the laboratory, to the relativistic thermal plasmas present for example in pulsar winds. Laboratory HED relativistic plasmas to date have been those produced by laser beams of irradiance ˜ 10^18 to 10^22 W/cm^2 or by accelerator-produced HED electron beams. These have applications ranging from generation of intense x-rays to production of proton beams for radiation therapy to acceleration of electrons. Here we will focus on electron acceleration, a spectacular recent success and a rare

Applying automatic item generation to create cohesive physics testlets

Science.gov (United States)

Mindyarto, B. N.; Nugroho, S. E.; Linuwih, S.

2018-03-01

Computer-based testing has created the demand for large numbers of items. This paper discusses the production of cohesive physics testlets using an automatic item generation concepts and procedures. The testlets were composed by restructuring physics problems to reveal deeper understanding of the underlying physical concepts by inserting a qualitative question and its scientific reasoning question. A template-based testlet generator was used to generate the testlet variants. Using this methodology, 1248 testlet variants were effectively generated from 25 testlet templates. Some issues related to the effective application of the generated physics testlets in practical assessments were discussed.

Background risk of breast cancer and the association between physical activity and mammographic density.

Science.gov (United States)

Trinh, Thang; Eriksson, Mikael; Darabi, Hatef; Bonn, Stephanie E; Brand, Judith S; Cuzick, Jack; Czene, Kamila; Sjölander, Arvid; Bälter, Katarina; Hall, Per

2015-04-02

High physical activity has been shown to decrease the risk of breast cancer, potentially by a mechanism that also reduces mammographic density. We tested the hypothesis that the risk of developing breast cancer in the next 10 years according to the Tyrer-Cuzick prediction model influences the association between physical activity and mammographic density. We conducted a population-based cross-sectional study of 38,913 Swedish women aged 40-74 years. Physical activity was assessed using the validated web-questionnaire Active-Q and mammographic density was measured by the fully automated volumetric Volpara method. The 10-year risk of breast cancer was estimated using the Tyrer-Cuzick (TC) prediction model. Linear regression analyses were performed to assess the association between physical activity and volumetric mammographic density and the potential interaction with the TC breast cancer risk. Overall, high physical activity was associated with lower absolute dense volume. As compared to women with the lowest total activity level (association was seen for any type of physical activity among women with association between total activity and absolute dense volume was modified by the TC breast cancer risk (P interaction = 0.05). As anticipated, high physical activity was also associated with lower non-dense volume. No consistent association was found between physical activity and percent dense volume. Our results suggest that physical activity may decrease breast cancer risk through reducing mammographic density, and that the physical activity needed to reduce mammographic density may depend on background risk of breast cancer.

Fast physical random bit generation with chaotic semiconductor lasers

Science.gov (United States)

Uchida, Atsushi; Amano, Kazuya; Inoue, Masaki; Hirano, Kunihito; Naito, Sunao; Someya, Hiroyuki; Oowada, Isao; Kurashige, Takayuki; Shiki, Masaru; Yoshimori, Shigeru; Yoshimura, Kazuyuki; Davis, Peter

2008-12-01

Random number generators in digital information systems make use of physical entropy sources such as electronic and photonic noise to add unpredictability to deterministically generated pseudo-random sequences. However, there is a large gap between the generation rates achieved with existing physical sources and the high data rates of many computation and communication systems; this is a fundamental weakness of these systems. Here we show that good quality random bit sequences can be generated at very fast bit rates using physical chaos in semiconductor lasers. Streams of bits that pass standard statistical tests for randomness have been generated at rates of up to 1.7 Gbps by sampling the fluctuating optical output of two chaotic lasers. This rate is an order of magnitude faster than that of previously reported devices for physical random bit generators with verified randomness. This means that the performance of random number generators can be greatly improved by using chaotic laser devices as physical entropy sources.

Physical activity and bone mineral density in Italian middle-aged women

International Nuclear Information System (INIS)

Bidoli, Ettore; Schinella, Domenico; Franceschi, Silvia

1998-01-01

Osteoporosis is a major health issue in postmenopausal women on account of the association between low bone mineral density and fractures. A role of physical activity in the prevention and treatment of low bone mineral density is possible but still unclear. The relationship between low spine bone mineral density measured by means of dual photon absorptiometry at lumbar spines, and levels of past and recent physical activity has been assessed by means of a population-based screening study carried out on 1373 women (age 40-64 years) in the North-East of Italy. Physical activity at work and in leisure time was investigated for three specific periods of life: at age 12, between 15 and 19 years (during bone formative years), and in the recent years prior to the interview (30-39 or 50-59 years). Data were analysed comparing low versus high bone mineral density tertile (i.e., 458 and 461 women, respectively), after controlling for other known contributory factors in the development of osteoporosis. A positive association emerged with leisure time physical activity, with significant trends at age 15-19 (odds ratio (OR) for low versus high tertile of leisure time activity: 1.4, 95% confidence interval (CI): 0.8-2.4) and at most recent age (OR: 1.7, 95% CI: 1.1-2.6). Risk trends with occupational physical activity were less clear and non-statistically significant. The present Southern European cross-sectional study lends further support to the possibility that past and recent physical activity helps increasing bone mineral density in middle-aged women. Although the most beneficial type and intensity level of exercise has yet to be determined, the present results provide further evidence that participation in even moderate exercise programs should be encouraged

Exploration of Plasma Jets Approach to High Energy Density Physics. Final report

Energy Technology Data Exchange (ETDEWEB)

Chen, Chiping [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

2013-08-26

High-energy-density laboratory plasma (HEDLP) physics is an emerging, important area of research in plasma physics, nuclear physics, astrophysics, and particle acceleration. While the HEDLP regime occurs at extreme conditions which are often found naturally in space but not on the earth, it may be accessible by colliding high intensity plasmas such as high-energy-density plasma jets, plasmoids or compact toroids from plasma guns. The physics of plasma jets is investigated in the context of high energy density laboratory plasma research. This report summarizes results of theoretical and computational investigation of a plasma jet undergoing adiabatic compression and adiabatic expansion. A root-mean-squared (rms) envelope theory of plasma jets is developed. Comparison between theory and experiment is made. Good agreement between theory and experiment is found.

Forward modeling of gravity data using geostatistically generated subsurface density variations

Science.gov (United States)

Phelps, Geoffrey

2016-01-01

Using geostatistical models of density variations in the subsurface, constrained by geologic data, forward models of gravity anomalies can be generated by discretizing the subsurface and calculating the cumulative effect of each cell (pixel). The results of such stochastically generated forward gravity anomalies can be compared with the observed gravity anomalies to find density models that match the observed data. These models have an advantage over forward gravity anomalies generated using polygonal bodies of homogeneous density because generating numerous realizations explores a larger region of the solution space. The stochastic modeling can be thought of as dividing the forward model into two components: that due to the shape of each geologic unit and that due to the heterogeneous distribution of density within each geologic unit. The modeling demonstrates that the internally heterogeneous distribution of density within each geologic unit can contribute significantly to the resulting calculated forward gravity anomaly. Furthermore, the stochastic models match observed statistical properties of geologic units, the solution space is more broadly explored by producing a suite of successful models, and the likelihood of a particular conceptual geologic model can be compared. The Vaca Fault near Travis Air Force Base, California, can be successfully modeled as a normal or strike-slip fault, with the normal fault model being slightly more probable. It can also be modeled as a reverse fault, although this structural geologic configuration is highly unlikely given the realizations we explored.

Laser-driven strong magnetostatic fields with applications to charged beam transport and magnetized high energy-density physics

Science.gov (United States)

Santos, J. J.; Bailly-Grandvaux, M.; Ehret, M.; Arefiev, A. V.; Batani, D.; Beg, F. N.; Calisti, A.; Ferri, S.; Florido, R.; Forestier-Colleoni, P.; Fujioka, S.; Gigosos, M. A.; Giuffrida, L.; Gremillet, L.; Honrubia, J. J.; Kojima, S.; Korneev, Ph.; Law, K. F. F.; Marquès, J.-R.; Morace, A.; Mossé, C.; Peyrusse, O.; Rose, S.; Roth, M.; Sakata, S.; Schaumann, G.; Suzuki-Vidal, F.; Tikhonchuk, V. T.; Toncian, T.; Woolsey, N.; Zhang, Z.

2018-05-01

Powerful nanosecond laser-plasma processes are explored to generate discharge currents of a few 100 kA in coil targets, yielding magnetostatic fields (B-fields) in excess of 0.5 kT. The quasi-static currents are provided from hot electron ejection from the laser-irradiated surface. According to our model, which describes the evolution of the discharge current, the major control parameter is the laser irradiance Ilasλlas2 . The space-time evolution of the B-fields is experimentally characterized by high-frequency bandwidth B-dot probes and proton-deflectometry measurements. The magnetic pulses, of ns-scale, are long enough to magnetize secondary targets through resistive diffusion. We applied it in experiments of laser-generated relativistic electron transport through solid dielectric targets, yielding an unprecedented 5-fold enhancement of the energy-density flux at 60 μm depth, compared to unmagnetized transport conditions. These studies pave the ground for magnetized high-energy density physics investigations, related to laser-generated secondary sources of radiation and/or high-energy particles and their transport, to high-gain fusion energy schemes, and to laboratory astrophysics.

Ultra low density biodegradable shape memory polymer foams with tunable physical properties

Science.gov (United States)

Singhal, Pooja; Wilson, Thomas S.; Cosgriff-Hernandez, Elizabeth; Maitland, Duncan J.

2017-12-12

Compositions and/or structures of degradable shape memory polymers (SMPs) ranging in form from neat/unfoamed to ultra low density materials of down to 0.005 g/cc density. These materials show controllable degradation rate, actuation temperature and breadth of transitions along with high modulus and excellent shape memory behavior. A method of m ly low density foams (up to 0.005 g/cc) via use of combined chemical and physical aking extreme blowing agents, where the physical blowing agents may be a single compound or mixtures of two or more compounds, and other related methods, including of using multiple co-blowing agents of successively higher boiling points in order to achieve a large range of densities for a fixed net chemical composition. Methods of optimization of the physical properties of the foams such as porosity, cell size and distribution, cell openness etc. of these materials, to further expand their uses and improve their performance.

Physical Principle for Generation of Randomness

Science.gov (United States)

Zak, Michail

2009-01-01

A physical principle (more precisely, a principle that incorporates mathematical models used in physics) has been conceived as the basis of a method of generating randomness in Monte Carlo simulations. The principle eliminates the need for conventional random-number generators. The Monte Carlo simulation method is among the most powerful computational methods for solving high-dimensional problems in physics, chemistry, economics, and information processing. The Monte Carlo simulation method is especially effective for solving problems in which computational complexity increases exponentially with dimensionality. The main advantage of the Monte Carlo simulation method over other methods is that the demand on computational resources becomes independent of dimensionality. As augmented by the present principle, the Monte Carlo simulation method becomes an even more powerful computational method that is especially useful for solving problems associated with dynamics of fluids, planning, scheduling, and combinatorial optimization. The present principle is based on coupling of dynamical equations with the corresponding Liouville equation. The randomness is generated by non-Lipschitz instability of dynamics triggered and controlled by feedback from the Liouville equation. (In non-Lipschitz dynamics, the derivatives of solutions of the dynamical equations are not required to be bounded.)

Promoting Plasma Physics as a Career: A Generational Approach

Science.gov (United States)

Morgan, James

2005-10-01

A paradigm shift is occurring in education physics programs. Educators are shifting from the traditional teaching focus to concentrate on student learning. Students are unaware of physics as a career, plasma physics or the job opportunities afforded to them with a physics degree. The physics profession needs to promote itself to the younger generations, or specifically the millennial generation (Born in the 1980's-2000's). Learning styles preferred by ``Millennials'' include a technological environment that promotes learning through active task performance rather than passive attendance at lectures. Millennials respond well to anything experiential and will be motivated by opportunities for creativity and challenging learning environments. The open-ended access to information, the ability to tailor learning paths, and continuous and instantaneous performance assessment offer flexibility in the design of curricula as well as in the method of delivery. Educators need to understand the millennial generation, appeal to their motivations and offer a learning environment designed for their learning style. This poster suggests promoting a physics career by focusing on generational learning styles and preferences.

General-purpose event generators for LHC physics

CERN Document Server

Buckley, Andy; Gieseke, Stefan; Grellscheid, David; Hoche, Stefan; Hoeth, Hendrik; Krauss, Frank; Lonnblad, Leif; Nurse, Emily; Richardson, Peter; Schumann, Steffen; Seymour, Michael H.; Sjostrand, Torbjorn; Skands, Peter; Webber, Bryan

2011-01-01

We review the physics basis, main features and use of general-purpose Monte Carlo event generators for the simulation of proton-proton collisions at the Large Hadron Collider. Topics included are: the generation of hard-scattering matrix elements for processes of interest, at both leading and next-to-leading QCD perturbative order; their matching to approximate treatments of higher orders based on the showering approximation; the parton and dipole shower formulations; parton distribution functions for event generators; non-perturbative aspects such as soft QCD collisions, the underlying event and diffractive processes; the string and cluster models for hadron formation; the treatment of hadron and tau decays; the inclusion of QED radiation and beyond-Standard-Model processes. We describe the principal features of the ARIADNE, Herwig++, PYTHIA 8 and SHERPA generators, together with the Rivet and Professor validation and tuning tools, and discuss the physics philosophy behind the proper use of these generators ...

The next generation mass storage devices - Physical principles and current status

Science.gov (United States)

Wang, L.; Gai, S.

2014-04-01

The amount of digital data today has been increasing at a phenomenal rate due to the widespread digitalisation service in almost every industry. The need to store such ever-increasing data aggressively triggers the requirement to augment the storage capacity of the conventional storage technologies. Unfortunately, the physical limitations that conventional forms face have severely handicapped their potential to meet the storage need from both consumer and industry point of view. The focus has therefore been switched into the development of the innovative data storage technologies such as scanning probe memory, nanocrystal memory, carbon nanotube memory, DNA memory, and organic memory. In this paper, we review the physical principles of these emerging storage technologies and their superiorities as the next generation data storage device, as well as their respective technical challenges on further enhancing the storage capacity. We also compare these novel technologies with the mainstream data storage means according to the technology roadmap on areal density.

Vorticity generation and evolution in shock-accelerated density-stratified interfaces

International Nuclear Information System (INIS)

Yang, X.; Chern, I.; Zabusky, N.J.; Samtaney, R.; Hawley, J.F.

1992-01-01

The results of direct numerical simulations of inviscid planar shock-accelerated density-stratified interfaces in two dimensions are presented and compared with shock tube experiments of Haas [(private communication, 1988)] and Sturtevant [in Shock Tubes and Waves, edited by H. Gronig (VCH, Berlin, 1987), p. 89] . Heavy-to-light (''slow/fast or s/f) and light-to-heavy (''fast/slow,'' or f/s) gas interfaces are examined and early-time impulsive vorticity deposition and the evolution of coherent vortex structures are emphasized and quantified. The present second-order Godunov scheme yields excellent agreement with shock-polar analyses at early time. A more physical vortex interpretation explains the commonly used (i.e., linear paradigm) designations of ''unstable'' and ''stable'' for the f/s and s/f interfaces, respectively. The later time events are Rayleigh--Taylor like and can be described in terms of the evolution of a vortex layer (large-scale translation and rotation): asymmetric tip vortex ''roll-up'' and ''binding;'' layer ''instability;'' convective mixing; and baroclinic vorticity generation from secondary shock--interface interactions

Density of Plutonium Turnings Generated from Machining Activities

Energy Technology Data Exchange (ETDEWEB)

Gonzales, John Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vigil, Duane M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Jachimowski, Thomas A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Archuleta, Alonso [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Arellano, Gerald Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Melton, Vince Lee [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-10-20

The purpose of this project was to determine the density of plutonium (Pu) turnings generated from the range of machining activities, using both surrogate material and machined Pu turnings. Verify that 500 grams (g) of plutonium will fit in a one quart container using a surrogate equivalent volume and that 100 grams of Pu will fit in a one quart Savy container.

Volumetric breast density measurement: sensitivity analysis of a relative physics approach.

Science.gov (United States)

Lau, Susie; Ng, Kwan Hoong; Abdul Aziz, Yang Faridah

2016-10-01

To investigate the sensitivity and robustness of a volumetric breast density (VBD) measurement system to errors in the imaging physics parameters including compressed breast thickness (CBT), tube voltage (kVp), filter thickness, tube current-exposure time product (mAs), detector gain, detector offset and image noise. 3317 raw digital mammograms were processed with Volpara(®) (Matakina Technology Ltd, Wellington, New Zealand) to obtain fibroglandular tissue volume (FGV), breast volume (BV) and VBD. Errors in parameters including CBT, kVp, filter thickness and mAs were simulated by varying them in the Digital Imaging and Communications in Medicine (DICOM) tags of the images up to ±10% of the original values. Errors in detector gain and offset were simulated by varying them in the Volpara configuration file up to ±10% from their default values. For image noise, Gaussian noise was generated and introduced into the original images. Errors in filter thickness, mAs, detector gain and offset had limited effects on FGV, BV and VBD. Significant effects in VBD were observed when CBT, kVp, detector offset and image noise were varied (p applications such as tracking density change over time, it remains to be seen how accurate the measures need to be.

The GENIE Neutrino Monte Carlo Generator: Physics and User Manual

Energy Technology Data Exchange (ETDEWEB)

Andreopoulos, Costas [Univ. of Liverpool (United Kingdom). Dept. of Physics; Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL). Particle Physics Dept.; Barry, Christopher [Univ. of Liverpool (United Kingdom). Dept. of Physics; Dytman, Steve [Univ. of Pittsburgh, PA (United States). Dept. of Physics and Astronomy; Gallagher, Hugh [Tufts Univ., Medford, MA (United States). Dept. of Physics and Astronomy; Golan, Tomasz [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Univ. of Rochester, NY (United States). Dept. of Physics and Astronomy; Hatcher, Robert [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Perdue, Gabriel [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Yarba, Julia [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

2015-10-20

GENIE is a suite of products for the experimental neutrino physics community. This suite includes i) a modern software framework for implementing neutrino event generators, a state-of-the-art comprehensive physics model and tools to support neutrino interaction simulation for realistic experimental setups (the Generator product), ii) extensive archives of neutrino, charged-lepton and hadron scattering data and software to produce a comprehensive set of data/MC comparisons (the Comparisons product), and iii) a generator tuning framework and fitting applications (the Tuning product). This book provides the definite guide for the GENIE Generator: It presents the software architecture and a detailed description of its physics model and official tunes. In addition, it provides a rich set of data/MC comparisons that characterise the physics performance of GENIE. Detailed step-by-step instructions on how to install and configure the Generator, run its applications and analyze its outputs are also included.

Generation of pyroclastic density currents from pyroclastic fountaining or transient explosions: insights from large scale experiments

Energy Technology Data Exchange (ETDEWEB)

Sulpizio, Roberto; Dellino, Pierfrancesco; Mele, Daniela; La Volpe, Luigi [CIRISIVU, c/o Dipartimento Geomineralogico, via Orabona 4, 70125, Bari (Italy)], E-mail: r.sulpizio@geomin.uniba.it

2008-10-01

Pyroclastic density currents (PDCs) are among the most amazing, complex and dangerous volcanic phenomena. They are moving mixtures of particles and gas that flow across the ground, and originate in different ways and from various sources, during explosive eruptions or gravity-driven collapse of domes. We present results from experimental work to investigate the generation of large-scale, multiphase, gravity-driven currents. The experiments described here are particularly devoted to understanding the inception and development of PDCs under impulsive injection conditions by means of the fast application of a finite stress to a finite mass of pyroclastic particles via expansion of compressed gas. We find that, in summary, PDC generation from collapse of pressure-adjusted or overpressurised pyroclastic jets critically depends on behaviour of injection into the atmosphere, which controls the collapsing mechanisms and then the physical parameters of the initiating current.

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

Science.gov (United States)

Sibeck, David G.; Allen, R.; Aryan, H.; Bodewits, D.; Brandt, P.; Branduardi-Raymont, G.; Brown, G.; Carter, J. A.; Collado-Vega, Y. M.; Collier, M. R.; Connor, H. K.; Cravens, T. E.; Ezoe, Y.; Fok, M.-C.; Galeazzi, M.; Gutynska, O.; Holmström, M.; Hsieh, S.-Y.; Ishikawa, K.; Koutroumpa, D.; Kuntz, K. D.; Leutenegger, M.; Miyoshi, Y.; Porter, F. S.; Purucker, M. E.; Read, A. M.; Raeder, J.; Robertson, I. P.; Samsonov, A. A.; Sembay, S.; Snowden, S. L.; Thomas, N. E.; von Steiger, R.; Walsh, B. M.; Wing, S.

2018-06-01

Both heliophysics and planetary physics seek to understand the complex nature of the solar wind's interaction with solar system obstacles like Earth's magnetosphere, the ionospheres of Venus and Mars, and comets. Studies with this objective are frequently conducted with the help of single or multipoint in situ electromagnetic field and particle observations, guided by the predictions of both local and global numerical simulations, and placed in context by observations from far and extreme ultraviolet (FUV, EUV), hard X-ray, and energetic neutral atom imagers (ENA). Each proposed interaction mechanism (e.g., steady or transient magnetic reconnection, local or global magnetic reconnection, ion pick-up, or the Kelvin-Helmholtz instability) generates diagnostic plasma density structures. The significance of each mechanism to the overall interaction (as measured in terms of atmospheric/ionospheric loss at comets, Venus, and Mars or global magnetospheric/ionospheric convection at Earth) remains to be determined but can be evaluated on the basis of how often the density signatures that it generates are observed as a function of solar wind conditions. This paper reviews efforts to image the diagnostic plasma density structures in the soft (low energy, 0.1-2.0 keV) X-rays produced when high charge state solar wind ions exchange electrons with the exospheric neutrals surrounding solar system obstacles. The introduction notes that theory, local, and global simulations predict the characteristics of plasma boundaries such the bow shock and magnetopause (including location, density gradient, and motion) and regions such as the magnetosheath (including density and width) as a function of location, solar wind conditions, and the particular mechanism operating. In situ measurements confirm the existence of time- and spatial-dependent plasma density structures like the bow shock, magnetosheath, and magnetopause/ionopause at Venus, Mars, comets, and the Earth. However, in situ

Investigation of Physical Processes Limiting Plasma Density in DIII--D

Science.gov (United States)

Maingi, R.

1996-11-01

Understanding the physical processes which limit operating density is crucial in achieving peak performance in confined plasmas. Studies from many of the world's tokamaks have indicated the existence(M. Greenwald, et al., Nucl. Fusion 28) (1988) 2199 of an operational density limit (Greenwald limit, n^GW_max) which is proportional to the plasma current and independent of heating power. Several theories have reproduced the current dependence, but the lack of a heating power dependence in the data has presented an enigma. This limit impacts the International Thermonuclear Experimental Reactor (ITER) because the nominal operating density for ITER is 1.5 × n^GW_max. In DIII-D, experiments are being conducted to understand the physical processes which limit operating density in H-mode discharges; these processes include X-point MARFE formation, high core recycling and neutral pressure, resistive MHD stability, and core radiative collapse. These processes affect plasma properties, i.e. edge/scrape-off layer conduction and radiation, edge pressure gradient and plasma current density profile, and core radiation, which in turn restrict the accessible density regime. With divertor pumping and D2 pellet fueling, core neutral pressure is reduced and X-point MARFE formation is effectively eliminated. Injection of the largest-sized pellets does cause transient formation of divertor MARFEs which occasionally migrate to the X-point, but these are rapidly extinguished in pumped discharges in the time between pellets. In contrast to Greenwald et al., it is found that the density relaxation time after pellets is largely independent of the density relative to the Greenwald limit. Fourier analysis of Mirnov oscillations indicates the de-stabilization and growth of rotating, tearing-type modes (m/n= 2/1) when the injected pellets cause large density perturbations, and these modes often reduce energy confinement back to L-mode levels. We are examining the mechanisms for de

Predicting oak density with ecological, physical, and soil indicators

Science.gov (United States)

Callie Jo Schweitzer; Adrian A. Lesak; Yong Wang

2006-01-01

We predicted density of oak species in the mid-Cumberland Plateau region of northeastern Alabama on the basis of basal area of tree associations based on light tolerances, physical site characteristics, and soil type. Tree basal area was determined for four species groups: oaks (Quercus spp.), hickories (Carya spp.), yellow-poplar...

Laser-driven strong magnetostatic fields with applications to charged beam transport and magnetized high energy-density physics

Science.gov (United States)

Santos, Joao

2017-10-01

Powerful laser-plasma processes are explored to generate discharge currents of a few 100 kA in coil targets, yielding magnetostatic fields (B-fields) in the kTesla range. The B-fields are measured by proton-deflectometry and high-frequency bandwidth B-dot probes. According to our modeling, the quasi-static currents are provided from hot electron ejection from the laser-irradiated surface, accounting for the space charge neutralization and the plasma magnetization. The major control parameter is the laser irradiance Iλ2 . The B-fields ns-scale is long enough to magnetize secondary targets through resistive diffusion. We applied it in experiments of laser-generated relativistic electron transport into solid dielectric targets, yielding an unprecedented enhancement of a factor 5 on the energy-density flux at 60 µm depth, compared to unmagnetized transport conditions. These studies pave the ground for magnetized high-energy density physics investigations, related to laser-generated secondary sources of radiation and/or high-energy particles and their transport, to high-gain fusion energy schemes and to laboratory astrophysics. We acknowledge funding from French National Agency for Research (ANR), Grant TERRE ANR-2011-BS04-014, and from EUROfusion Consortium, European Union's Horizon 2020 research and innovation programme, Grant 633053.

General-purpose event generators for LHC physics

International Nuclear Information System (INIS)

Buckley, Andy; Butterworth, Jonathan; Gieseke, Stefan; Grellscheid, David; Hoeche, Stefan; Hoeth, Hendrik; Krauss, Frank; Loennblad, Leif; Nurse, Emily; Richardson, Peter; Schumann, Steffen; Seymour, Michael H.; Sjoestrand, Torbjoern; Skands, Peter; Webber, Bryan

2011-01-01

We review the physics basis, main features and use of general-purpose Monte Carlo event generators for the simulation of proton-proton collisions at the Large Hadron Collider. Topics included are: the generation of hard scattering matrix elements for processes of interest, at both leading and next-to-leading QCD perturbative order; their matching to approximate treatments of higher orders based on the showering approximation; the parton and dipole shower formulations; parton distribution functions for event generators; non-perturbative aspects such as soft QCD collisions, the underlying event and diffractive processes; the string and cluster models for hadron formation; the treatment of hadron and tau decays; the inclusion of QED radiation and beyond Standard Model processes. We describe the principal features of the ARIADNE, Herwig++, PYTHIA 8 and SHERPA generators, together with the Rivet and Professor validation and tuning tools, and discuss the physics philosophy behind the proper use of these generators and tools. This review is aimed at phenomenologists wishing to understand better how parton-level predictions are translated into hadron-level events as well as experimentalists seeking a deeper insight into the tools available for signal and background simulation at the LHC.

General-purpose event generators for LHC physics

Energy Technology Data Exchange (ETDEWEB)

Buckley, Andy [PPE Group, School of Physics and Astronomy, University of Edinburgh, EH25 9PN (United Kingdom); Butterworth, Jonathan [Department of Physics and Astronomy, University College London, WC1E 6BT (United Kingdom); Gieseke, Stefan [Institute for Theoretical Physics, Karlsruhe Institute of Technology, D-76128 Karlsruhe (Germany); Grellscheid, David [Institute for Particle Physics Phenomenology, Durham University, DH1 3LE (United Kingdom); Hoeche, Stefan [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Hoeth, Hendrik; Krauss, Frank [Institute for Particle Physics Phenomenology, Durham University, DH1 3LE (United Kingdom); Loennblad, Leif [Department of Astronomy and Theoretical Physics, Lund University (Sweden); PH Department, TH Unit, CERN, CH-1211 Geneva 23 (Switzerland); Nurse, Emily [Department of Physics and Astronomy, University College London, WC1E 6BT (United Kingdom); Richardson, Peter [Institute for Particle Physics Phenomenology, Durham University, DH1 3LE (United Kingdom); Schumann, Steffen [Institute for Theoretical Physics, University of Heidelberg, 69120 Heidelberg (Germany); Seymour, Michael H. [School of Physics and Astronomy, University of Manchester, M13 9PL (United Kingdom); Sjoestrand, Torbjoern [Department of Astronomy and Theoretical Physics, Lund University (Sweden); Skands, Peter [PH Department, TH Unit, CERN, CH-1211 Geneva 23 (Switzerland); Webber, Bryan, E-mail: webber@hep.phy.cam.ac.uk [Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

2011-07-15

We review the physics basis, main features and use of general-purpose Monte Carlo event generators for the simulation of proton-proton collisions at the Large Hadron Collider. Topics included are: the generation of hard scattering matrix elements for processes of interest, at both leading and next-to-leading QCD perturbative order; their matching to approximate treatments of higher orders based on the showering approximation; the parton and dipole shower formulations; parton distribution functions for event generators; non-perturbative aspects such as soft QCD collisions, the underlying event and diffractive processes; the string and cluster models for hadron formation; the treatment of hadron and tau decays; the inclusion of QED radiation and beyond Standard Model processes. We describe the principal features of the ARIADNE, Herwig++, PYTHIA 8 and SHERPA generators, together with the Rivet and Professor validation and tuning tools, and discuss the physics philosophy behind the proper use of these generators and tools. This review is aimed at phenomenologists wishing to understand better how parton-level predictions are translated into hadron-level events as well as experimentalists seeking a deeper insight into the tools available for signal and background simulation at the LHC.

General-purpose event generators for LHC physics

Energy Technology Data Exchange (ETDEWEB)

Buckley, Andy; /Edinburgh U.; Butterworth, Jonathan; /University Coll. London; Gieseke, Stefan; /Karlsruhe U., ITP; Grellscheid, David; /Durham U., IPPP; Hoche, Stefan; /SLAC; Hoeth, Hendrik; Krauss, Frank; /Durham U., IPPP; Lonnblad, Leif; /Lund U., Dept. Theor. Phys. /CERN; Nurse, Emily; /University Coll. London; Richardson, Peter; /Durham U., IPPP; Schumann, Steffen; /Heidelberg U.; Seymour, Michael H.; /Manchester U.; Sjostrand, Torbjorn; /Lund U., Dept. Theor. Phys.; Skands, Peter; /CERN; Webber, Bryan; /Cambridge U.

2011-03-03

We review the physics basis, main features and use of general-purpose Monte Carlo event generators for the simulation of proton-proton collisions at the Large Hadron Collider. Topics included are: the generation of hard-scattering matrix elements for processes of interest, at both leading and next-to-leading QCD perturbative order; their matching to approximate treatments of higher orders based on the showering approximation; the parton and dipole shower formulations; parton distribution functions for event generators; non-perturbative aspects such as soft QCD collisions, the underlying event and diffractive processes; the string and cluster models for hadron formation; the treatment of hadron and tau decays; the inclusion of QED radiation and beyond-Standard-Model processes. We describe the principal features of the Ariadne, Herwig++, Pythia 8 and Sherpa generators, together with the Rivet and Professor validation and tuning tools, and discuss the physics philosophy behind the proper use of these generators and tools. This review is aimed at phenomenologists wishing to understand better how parton-level predictions are translated into hadron-level events as well as experimentalists wanting a deeper insight into the tools available for signal and background simulation at the LHC.

Relationship of Physical Activity Type, Nutrition, and Bone Mineral Density in Korean Adolescents

Directory of Open Access Journals (Sweden)

Yong Hwan Kim

2017-10-01

Full Text Available Bone density reaches its peak in the mid-20s, and it manifests as osteoporosis and osteopenia with aging. Bone density is affected by body mass index, muscle mass, nutritional calcium and vitamin D, various lifestyles, physical activity level, and high level of strength. The purpose of this study was to investigate the difference in diet and bone density according to physical activity level in growing male and female adolescents. This study involved 646 male and 581 female adolescents using data from the Korea National Health and Nutrition Examination in 2009-2011. The measurement of bone density consisted of dual-energy X-ray absorptiometry, and they were classified into low, middle, and high groups at different ages based on total bone mineral density. The Korean version of the International Physical Activity Questionnaire by the World Health Organization was used to measure physical activity level, and a survey regarding strength exercise and stretching was conducted. In the nutritional survey, data from a 24h recall were analyzed. One-way analysis of variance and chi-square test were conducted to examine the significance of any differences present. Even though there was no difference among groups in both males and females, there was a significant difference in weight (p0.05. In males, the high group showed significantly higher calorie intake (p=0.032, protein (p=0.015, calcium (p=0.043, and phosphorus (p=0.013 compared with the low group according to nutrition intake. In terms of physical activity level, there was significant a difference as the proportion of strength exercise more than 3 times a week was 18.1% and 27.2% in the low and high groups, respectively in males (p=0.046, and was 1.0% and 6.1% respectively in females (p=0.014. The proportion of high-intensity exercise 6-7 times a week also showed a significant difference as the low, middle, and high groups showed 5.1%, 5.5%, and 14.1%, respectively (p<0.001. Among adolescents, bone

The Atlas pulsed power facility for high energy density physics experiments

CERN Document Server

Miller, R B; Barr, G W; Bowman, D W; Cochrane, J C; Davis, H A; Elizondo, J M; Gribble, R F; Griego, J R; Hicks, R D; Hinckley, W B; Hosack, K W; Nielsen, K E; Parker, J V; Parsons, M O; Rickets, R L; Salazar, H R; Sánchez, P G; Scudder, D W; Shapiro, C; Thompson, M C; Trainor, R J; Valdez, G A; Vigil, B N; Watt, R G; Wysocki, F J; Kirbie, H C

1999-01-01

The Atlas facility, now under construction at Los Alamos National Laboratory (LANL), will provide a unique capability for performing high-energy-density experiments in support of weapon-physics and basic-research programs. Here, the authors describe how the primary element of Atlas is a 23-MJ capacitor bank, comprised of 96 separate Marx generators housed in 12 separate oil-filled tanks, surrounding a central target chamber. Each tank will house two, independently- removable maintenance units, with each maintenance unit consisting of four Marx modules. Each Marx module has four capacitors that can each be charged to a maximum of 60 kilovolts. When railgap switches are triggered, the Marx modules erect to a maximum of 240 kV. The parallel discharge of these 96 Marx modules will deliver a 30-MA current pulse with a 4-5-ys risetime to a cylindrical, imploding liner via 24 vertical, tri-plate, oil-insulated transmission lines. An experimental program for testing and certifying all Marx and transmission line compo...

Super fast physical-random number generation using laser diode frequency noises

Science.gov (United States)

Ushiki, Tetsuro; Doi, Kohei; Maehara, Shinya; Sato, Takashi; Ohkawa, Masashi; Ohdaira, Yasuo

2011-02-01

Random numbers can be classified as either pseudo- or physical-random in character. Pseudo-random numbers' periodicity renders them inappropriate for use in cryptographic applications, but naturally-generated physical-random numbers have no calculable periodicity, thereby making them ideally-suited to the task. The laser diode naturally produces a wideband "noise" signal that is believed to have tremendous capacity and great promise, for the rapid generation of physical-random numbers for use in cryptographic applications. We measured a laser diode's output, at a fast photo detector and generated physical-random numbers from frequency noises. We then identified and evaluated the binary-number-line's statistical properties. The result shows that physical-random number generation, at speeds as high as 40Gbps, is obtainable, using the laser diode's frequency noise characteristic.

Generation of quantum logic operations from physical Hamiltonians

International Nuclear Information System (INIS)

Zhang Jun; Whaley, K. Birgitta

2005-01-01

We provide a systematic analysis of the physical generation of single- and two-qubit quantum operations from Hamiltonians available in various quantum systems for scalable quantum information processing. We show that generation of single-qubit operations can be transformed into a steering problem on the Bloch sphere, which represents all R z -equivalence classes of single-qubit operations, whereas the two-qubit problem can be generally transformed into a steering problem in a tetrahedron representing all the local-equivalence classes of two-qubit operations (the Weyl chamber). We use this approach to investigate several physical examples for the generation of two-qubit operations. The steering approach provides useful guidance for the realization of various quantum computation schemes

Generation of density perturbations by inflation in scalar-tensor gravity theories

Science.gov (United States)

Seshadri, T. R.

1992-02-01

Density perturbations arising out of the quantum fluctuations in a Brans-Dicke field in the context of extended inflation have been studied. We have used a model in which the Brans-Dicke parameter varies with time. We find that the density perturbations are large in magnitude and have a scale invariant spectrum. The origin of these is discussed and it is shown that these place further constraints on the model. Address after 15 Octobr 1991: Department of Physics and Astrophysics, University of Delhi 110 007, India.

Effect of self-focusing on resonant third harmonic generation of laser in a rippled density plasma

International Nuclear Information System (INIS)

Kaur, Sukhdeep; Sharma, A. K.; Yadav, Sushila

2010-01-01

Resonant third harmonic generation by a Gaussian laser beam in a rippled density plasma is studied. The laser ponderomotive force induces second harmonic longitudinal velocity on electrons that couples with the static density ripple to produce a density perturbation at 2ω,2k+q, where ω and k are the frequency and wave number of the laser and q is the ripple wave number of the laser. This density perturbation beats with electron oscillatory velocity at ω,k-vector to produce a nonlinear current driving the third harmonic generation. In the regime of quadratic nonlinearity, the self-focusing of the laser enhances the third harmonic power. However, at higher intensity, plasma density is significantly reduced on the axis, detuning the third harmonic resonance and weakening the harmonic yield. Self-focusing causes enhancement in the efficiency of harmonic generation.

Physical and Microbiological Qualities of Kampong-Broiler Crossbred Chickens Meat Raised in Different Stocking Densities

Directory of Open Access Journals (Sweden)

C. A. Patria

2016-12-01

Full Text Available The crossbreeding between broiler and kampong chickens has been performed to develop a kampong-broiler strain chicken. The chicken stocking condition needs more attention as a part of animal welfare. This study was performed to identify the relationship between the stocking density and the stress based on Temperature Humidity Index (THI and the effect of stocking density on meat quality, i.e., physical, microbiological, and organoleptic. Ninety DOCs of Kampong-Broiler (KB were assigned into a completely randomized design with 3 treatments of stocking density  i.e., 8, 10, and 12 birds m-2. Each treatment was replicated 3 times. The experimental chickens were housed in 9 blocks of housing each with 1 x 1 m2 size. Data on physical and microbiology of meat qualities were analyzed with analysis of variance and continued with Duncan’s multiple range test. The organoleptic data were analyzed by using Kruskal-Wallis test. The result showed that the stocking density did not significantly affect the physical and hedonic quality of KB chicken’s breast. The stocking densities significantly affected (P<0.05 the microbiological variables of breast meat. The average value of THI during maintenance reached 28.98±1.25–29.33±1.32oC. The higher the animal density the higher the THI value that correlated to the stress condition. However, high stocking density did not affect the physical and hedonic quality of breast meat,  thus it can be accepted by the consumers. The higher the stocking density the higher the total plate count, Escherichia coli, and Staphylococcus aureus, without the presence of Salmonella sp. The meat quality of KB chickens raised in the stocking density of 10 birds m-2 meets the requirement of SNI 01-3924-2009.

Similarity and self-similarity in high energy density physics: application to laboratory astrophysics

International Nuclear Information System (INIS)

Falize, E.

2008-10-01

The spectacular recent development of powerful facilities allows the astrophysical community to explore, in laboratory, astrophysical phenomena where radiation and matter are strongly coupled. The titles of the nine chapters of the thesis are: from high energy density physics to laboratory astrophysics; Lie groups, invariance and self-similarity; scaling laws and similarity properties in High-Energy-Density physics; the Burgan-Feix-Munier transformation; dynamics of polytropic gases; stationary radiating shocks and the POLAR project; structure, dynamics and stability of optically thin fluids; from young star jets to laboratory jets; modelling and experiences for laboratory jets

High energy density physics studies at the facility for antiprotons and ion research: the HEDgeHOB collaboration

International Nuclear Information System (INIS)

Tahir, N.A.; Stoehlker, T.; Geissel, H.; Shutov, A.; Lomonosov, I.V.; Fortov, V.E.; Piriz, A.R.; Redmer, R.; Deutsch, C.

2011-01-01

The forthcoming Facility for Antiprotons and Ion Research (FAIR) at Darmstadt, is going to be a unique accelerator facility that will deliver high quality, strongly bunched, well focused, intense beams of heavy ions that will lead to unprecedented specific power deposition in solid matter. This will generate macroscopic samples of High Energy Density (HED) matter with fairly uniform physical conditions. These samples can be used to study the thermophysical and transport properties of HED matter. Extensive theoretical work has been carried out over the past decade to design numerous dedicated experiments to study HED physics at the FAIR, which has provided the basis for the HEDgeHOB (High Energy Density Matter Generated by Heavy Ion Beams) scientific proposal. This work is still in progress as the feasibility studies for more experimental schemes are being carried out. Another, very important research area that will benefit tremendously from the FAIR facility, is the production of radioactive beams. A superconducting fragment separator, Super-FRS is being designed for the production and separation of rare radioactive isotopes. Unlike the HED targets, the Super-FRS production target should not be destroyed or damaged by the beam, but should remain intact during the long experimental campaign. However, the high level of specific power deposited in the production target by the high intensity ion beam at FAIR, could cause serious problems to the target survival. These HED issues related to the Super-FRS production target are also discussed in the present paper (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

The Physical Density of the City—Deconstruction of the Delusive Density Measure with Evidence from Two European Megacities

Directory of Open Access Journals (Sweden)

Hannes Taubenböck

2016-11-01

Full Text Available Density is among the most important descriptive as well as normative measures in urban research. While its basic concept is generally understandable, approaches towards the density measure are manifold, diverse and of multidimensional complexity. This evolves from differing thematic, spatial and calculative specifications. Consequently, applied density measures are often used in a subjective, non-transparent, unspecific and thus non-comparable manner. In this paper, we aim at a systematic deconstruction of the measure density. Varying thematic, spatial and calculative dimensions show significant influence on the measure. With both quantitative and qualitative techniques of evaluation, we assess the particular influences on the measure density. To do so, we reduce our experiment setting to a mere physical perspective; that is, the quantitative measures building density, degree of soil sealing, floor space density and, more specifically, the density of generic structural classes such as open spaces and highest built-up density areas. Using up-to-date geodata derived from remote sensing and volunteered geographic information, we build upon high-quality spatial information products such as 3-D city models. Exemplified for the comparison of two European megacities, namely Paris and London, we reveal and systemize necessary variables to be clearly defined for meaningful conclusions using the density measure.

Report of the Interagency Task Force on High Energy Density Physics

Energy Technology Data Exchange (ETDEWEB)

None

2007-08-01

Identifies the needs for improving Federal stewardship of specific aspects of high energy density physics, particularly the study of high energy density plasmas in the laboratory, and strengthening university activities in this latter discipline. The report articulates how HEDP fits into the portfolio of federally funded missions and includes agency actions to be taken that are necessary to further this area of study consistent with Federal priorities and plans, while being responsive to the needs of the scientific community.

Report of the Interagency Task Force on High Energy Density Physics

International Nuclear Information System (INIS)

2007-01-01

Identifies the needs for improving Federal stewardship of specific aspects of high energy density physics, particularly the study of high energy density plasmas in the laboratory, and strengthening university activities in this latter discipline. The report articulates how HEDP fits into the portfolio of federally funded missions and includes agency actions to be taken that are necessary to further this area of study consistent with Federal priorities and plans, while being responsive to the needs of the scientific community

Work- and travel-related physical activity and alcohol consumption: relationship with bone mineral density and calcaneal quantitative ultrasonometry.

Science.gov (United States)

Sritara, Chanika; Thakkinstian, Ammarin; Ongphiphadhanakul, Boonsong; Pornsuriyasak, Prapaporn; Warodomwichit, Daruneewan; Akrawichien, Tawatchai; Vathesatogkit, Prin; Sritara, Piyamitr

2015-01-01

A number of healthy workers rarely exercise because of a lack of time or resources. Physical activity related to work and everyday travel may be more feasible, but evidence of its beneficial effect on bone health is scarce. We assessed if this form of physical activity was associated with higher bone mineral density (BMD) and stiffness index (SI) when adjusted for recreational physical activity, age, body mass index, smoking, alcohol consumption, education, and serum level of 25-hydroxyvitamin D. Healthy workers, aged 25-54 yr, of the Electricity Generating Authority of Thailand were surveyed. The outcomes were BMD (lumbar spine, femoral neck, and total hip) and calcaneal SI. Physical activity was estimated using the global physical activity questionnaire and considered active when >600 metabolic equivalent tasks (min). Of 2268 subjects, 74% were men. Active male subjects had significantly higher BMD at the femoral neck and total hip (pwomen (p>0.05). In men, work and travel physical activity seems beneficial to male bone health; hence, it should be encouraged. Furthermore, smoking appeared harmful while moderate alcohol consumption was beneficial. Copyright © 2015 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.

Effect of burnup history by moderator density on neutron-physical characteristics of WWER-1000 core

International Nuclear Information System (INIS)

Ovdiienko, I.; Kuchin, A.; Khalimonchuk, V.; Ieremenko, M.

2011-01-01

Results of assessment of burnup history effect by moderator density on neutron physical characteristics of WWER-1000 core are presented on example of stationary fuel loading with Russian design fuel assembly TWSA and AER benchmark for Khmelnitsky NPP that was proposed by TUV and SSTC NRC at nineteenth symposium. Assessment was performed by DYN3D code and cross section library sets generated by HELIOS code. Burnup history was taken into account by preparing of numerous cross section sets with different isotopic composition each of which was obtained by burning under different moderator density. For analysis of history effect 20 cross section sets were prepared for each fuel assembly corresponded to each of 20 axial layers of reactor core model for DYN3D code. Four fuel cycles were modeled both for stationary fuel loading with TWSA and AER benchmark for Khmelnitsky NPP to obtain steady value of error due to neglect of burnup history effect. Main attention of study was paid to effect of burnup history by moderator density to axial power distribution. Results of study for AER benchmark were compared with experimental values of axial power distribution for fuel assemblies of first, second, third and fourth year operation. (Authors)

Generation of Stationary Non-Gaussian Time Histories with a Specified Cross-spectral Density

Directory of Open Access Journals (Sweden)

David O. Smallwood

1997-01-01

Full Text Available The paper reviews several methods for the generation of stationary realizations of sampled time histories with non-Gaussian distributions and introduces a new method which can be used to control the cross-spectral density matrix and the probability density functions (pdfs of the multiple input problem. Discussed first are two methods for the specialized case of matching the auto (power spectrum, the skewness, and kurtosis using generalized shot noise and using polynomial functions. It is then shown that the skewness and kurtosis can also be controlled by the phase of a complex frequency domain description of the random process. The general case of matching a target probability density function using a zero memory nonlinear (ZMNL function is then covered. Next methods for generating vectors of random variables with a specified covariance matrix for a class of spherically invariant random vectors (SIRV are discussed. Finally the general case of matching the cross-spectral density matrix of a vector of inputs with non-Gaussian marginal distributions is presented.

Physics of frequency-modulated comb generation in quantum-well diode lasers

Science.gov (United States)

Dong, Mark; Cundiff, Steven T.; Winful, Herbert G.

2018-05-01

We investigate the physical origin of frequency-modulated combs generated from single-section semiconductor diode lasers based on quantum wells, isolating the essential physics necessary for comb generation. We find that the two effects necessary for comb generation—spatial hole burning (leading to multimode operation) and four-wave mixing (leading to phase locking)—are indeed present in some quantum-well systems. The physics of comb generation in quantum wells is similar to that in quantum dot and quantum cascade lasers. We discuss the nature of the spectral phase and some important material parameters of these diode lasers.

From Swords to Plowshares: The US/Russian Collaboration in High Energy Density Physics Using Pulsed Power

International Nuclear Information System (INIS)

Younger, S.M.; Fowler, C.M.; Lindemuth, I.; Chernyshev, V.K.; Mokhov, V.N.; Pavlovskii, A.I.

1999-01-01

Since 1992, the All-Russian Scientific Research Institute of Experimental Physics and the Los Alamos National Laboratory, the institutes that designed the first nuclear weapons of the Soviet Union and the US, respectively, have been working together in fundamental research related to pulsed power and high energy density science. This collaboration has enabled scientists formerly engaged in weapons activities to redirect their attention to peaceful pursuits of wide benefit to the technical community. More than thirty joint experiments have been performed at Sarov and Los Alamos in areas as diverse as solid state physics in high magnetic fields, fusion plasma formation, isentropic compression of noble gases, and explosively driven-high current generation technology. Expanding on the introductory comments of the conference plenary presentation, this paper traces the origins of this collaboration and briefly reviews the scientific accomplishments. Detailed reports of the scientific accomplishments can be found in other papers in these proceedings and in other publications

Density-dependent effects on physical condition and reproduction in North American elk: an experimental test.

Science.gov (United States)

Kelley M. Stewart; R. Terry Bowyer; Brian L. Dick; Bruce K. Johnson; John G. Kie

2005-01-01

Density dependence plays a key role in life-history characteristics and population ecology of large, herbivorous mammals. We designed a manipulative experiment to test hypotheses relating effects of density-dependent mechanisms on physical condition and fecundity of North American elk (Cervus elaphus) by creating populations at low and high density...

Modern particle physics event generation with WHIZARD

International Nuclear Information System (INIS)

Reuter, J.; Bach, F.; Chokoufe, B.; Kilian, W.; Sekulla, M.; Ohl, T.; Weiss, C.; Siegen Univ.

2014-01-01

We describe the multi-purpose Monte-Carlo event generator WHIZARD for the simulation of high-energy particle physics experiments. Besides the presentation of the general features of the program like SM physics, BSM physics, and QCD effects, special emphasis is given to the support of the most accurate simulation of the collider environments at hadron colliders and especially at future linear lepton colliders. On the more technical side, the very recent code refactoring towards a completely object-oriented software package to improve maintainability, flexibility and code development are discussed. Finally, we present ongoing work and future plans regarding higher-order corrections, more general model support including the setup to search for new physics in vector boson scattering at the LHC, as well as several lines of performance improvements.

Modern Particle Physics Event Generation with WHIZARD

Science.gov (United States)

Reuter, J.; Bach, F.; Chokoufé, B.; Kilian, W.; Ohl, T.; Sekulla, M.; Weiss, C.

2015-05-01

We describe the multi-purpose Monte-Carlo event generator WHIZARD for the simulation of high-energy particle physics experiments. Besides the presentation of the general features of the program like SM physics, BSM physics, and QCD effects, special emphasis will be given to the support of the most accurate simulation of the collider environments at hadron colliders and especially at future linear lepton colliders. On the more technical side, the very recent code refactoring towards a completely object-oriented software package to improve maintainability, flexibility and code development will be discussed. Finally, we present ongoing work and future plans regarding higher-order corrections, more general model support including the setup to search for new physics in vector boson scattering at the LHC, as well as several lines of performance improvements.

Modern Particle Physics Event Generation with WHIZARD

International Nuclear Information System (INIS)

Reuter, J; Bach, F; Chokoufé, B; Weiss, C; Kilian, W; Sekulla, M; Ohl, T

2015-01-01

We describe the multi-purpose Monte-Carlo event generator WHIZARD for the simulation of high-energy particle physics experiments. Besides the presentation of the general features of the program like SM physics, BSM physics, and QCD effects, special emphasis will be given to the support of the most accurate simulation of the collider environments at hadron colliders and especially at future linear lepton colliders. On the more technical side, the very recent code refactoring towards a completely object-oriented software package to improve maintainability, flexibility and code development will be discussed. Finally, we present ongoing work and future plans regarding higher-order corrections, more general model support including the setup to search for new physics in vector boson scattering at the LHC, as well as several lines of performance improvements. (paper)

A Fiber-Optic System Generating Pulses of High Spectral Density

Science.gov (United States)

Abramov, A. S.; Zolotovskii, I. O.; Korobko, D. A.; Fotiadi, A. A.

2018-03-01

A cascade fiber-optic system that generates pulses of high spectral density by using the effect of nonlinear spectral compression is proposed. It is demonstrated that the shape of the pulse envelope substantially influences the degree of compression of its spectrum. In so doing, maximum compression is achieved for parabolic pulses. The cascade system includes an optical fiber exhibiting normal dispersion that decreases along the fiber length, thereby ensuring that the pulse envelope evolves toward a parabolic shape, along with diffraction gratings and a fiber spectral compressor. Based on computer simulation, we determined parameters of cascade elements leading to maximum spectral density of radiation originating from a subpicosecond laser pulse of medium energy.

Extreme hydrogen plasma densities achieved in a linear plasma generator

NARCIS (Netherlands)

Rooij, van G.J.; Veremiyenko, V.P.; Goedheer, W.J.; Groot, de B.; Kleyn, A.W.; Smeets, P.H.M.; Versloot, T.W.; Whyte, D.G.; Engeln, R.A.H.; Schram, D.C.; Lopes Cardozo, N.J.

2007-01-01

A magnetized hydrogen plasma beam was generated with a cascaded arc, expanding in a vacuum vessel at an axial magnetic field of up to 1.6 T. Its characteristics were measured at a distance of 4 cm from the nozzle: up to a 2 cm beam diameter, 7.5×1020 m-3 electron density, ~2 eV electron and ion

Physics of thermo-acoustic sound generation

Science.gov (United States)

Daschewski, M.; Boehm, R.; Prager, J.; Kreutzbruck, M.; Harrer, A.

2013-09-01

We present a generalized analytical model of thermo-acoustic sound generation based on the analysis of thermally induced energy density fluctuations and their propagation into the adjacent matter. The model provides exact analytical prediction of the sound pressure generated in fluids and solids; consequently, it can be applied to arbitrary thermal power sources such as thermophones, plasma firings, laser beams, and chemical reactions. Unlike existing approaches, our description also includes acoustic near-field effects and sound-field attenuation. Analytical results are compared with measurements of sound pressures generated by thermo-acoustic transducers in air for frequencies up to 1 MHz. The tested transducers consist of titanium and indium tin oxide coatings on quartz glass and polycarbonate substrates. The model reveals that thermo-acoustic efficiency increases linearly with the supplied thermal power and quadratically with thermal excitation frequency. Comparison of the efficiency of our thermo-acoustic transducers with those of piezoelectric-based airborne ultrasound transducers using impulse excitation showed comparable sound pressure values. The present results show that thermo-acoustic transducers can be applied as broadband, non-resonant, high-performance ultrasound sources.

Advanced Machine Learning for Classification, Regression, and Generation in Jet Physics

CERN Multimedia

CERN. Geneva

2017-01-01

There is a deep connection between machine learning and jet physics - after all, jets are defined by unsupervised learning algorithms. Jet physics has been a driving force for studying modern machine learning in high energy physics. Domain specific challenges require new techniques to make full use of the algorithms. A key focus is on understanding how and what the algorithms learn. Modern machine learning techniques for jet physics are demonstrated for classification, regression, and generation. In addition to providing powerful baseline performance, we show how to train complex models directly on data and to generate sparse stacked images with non-uniform granularity.

Development of a testlet generator in re-engineering the Indonesian physics national-exams

Science.gov (United States)

Mindyarto, Budi Naini; Mardapi, Djemari; Bastari

2017-08-01

The Indonesian Physics national-exams are end-of-course summative assessments that could be utilized to support the assessment for learning in physics educations. This paper discusses the development and evaluation of a testlet generator based on a re-engineering of Indonesian physics national exams. The exam problems were dissected and decomposed into testlets revealing the deeper understanding of the underlying physical concepts by inserting a qualitative question and its scientific reasoning question. A template-based generator was built to facilitate teachers in generating testlet variants that would be more conform to students' scientific attitude development than their original simple multiple-choice formats. The testlet generator was built using open source software technologies and was evaluated focusing on the black-box testing by exploring the generator's execution, inputs and outputs. The results showed the correctly-performed functionalities of the developed testlet generator in validating inputs, generating testlet variants, and accommodating polytomous item characteristics.

Anomalous evolution of Ar metastable density with electron density in high density Ar discharge

International Nuclear Information System (INIS)

Park, Min; Chang, Hong-Young; You, Shin-Jae; Kim, Jung-Hyung; Shin, Yong-Hyeon

2011-01-01

Recently, an anomalous evolution of argon metastable density with plasma discharge power (electron density) was reported [A. M. Daltrini, S. A. Moshkalev, T. J. Morgan, R. B. Piejak, and W. G. Graham, Appl. Phys. Lett. 92, 061504 (2008)]. Although the importance of the metastable atom and its density has been reported in a lot of literature, however, a basic physics behind the anomalous evolution of metastable density has not been clearly understood yet. In this study, we investigated a simple global model to elucidate the underlying physics of the anomalous evolution of argon metastable density with the electron density. On the basis of the proposed simple model, we reproduced the anomalous evolution of the metastable density and disclosed the detailed physics for the anomalous result. Drastic changes of dominant mechanisms for the population and depopulation processes of Ar metastable atoms with electron density, which take place even in relatively low electron density regime, is the clue to understand the result.

Laser fusion and high energy density science

International Nuclear Information System (INIS)

Kodama, Ryosuke

2005-01-01

High-power laser technology is now opening a variety of new fields of science and technology using laser-produced plasmas. The laser plasma is now recognized as one of the important tools for the investigation and application of matter under extreme conditions, which is called high energy density science. This chapter shows a variety of applications of laser-produced plasmas as high energy density science. One of the more attractive industrial and science applications is the generation of intense pulse-radiation sources, such as the generation of electro-magnetic waves in the ranges of EUV (Extreme Ultra Violet) to gamma rays and laser acceleration of charged particles. The laser plasma is used as an energy converter in this regime. The fundamental science applications of high energy density physics are shown by introducing laboratory astrophysics, the equation of state of high pressure matter, including warm dense matter and nuclear science. Other applications are also presented, such as femto-second laser propulsion and light guiding. Finally, a new systematization is proposed to explore the possibility of the high energy density plasma application, which is called high energy plasma photonics''. This is also exploration of the boundary regions between laser technology and beam optics based on plasma physics. (author)

The 5th Generation model of Particle Physics

Science.gov (United States)

Lach, Theodore

2009-05-01

The Standard model of Particle Physics is able to account for all known HEP phenomenon, yet it is not able to predict the masses of the quarks or leptons nor can it explain why they have their respective values. The Checker Board Model (CBM) predicts that there are 5 generation of quarks and leptons and shows a pattern to those masses, namely each three quarks or leptons (within adjacent generations or within a generation) are related to each other by a geometric mean relationship. A 2D structure of the nucleus can be imaged as 2D plate spinning on its axis, it would for all practical circumstances appear to be a 3D object. The masses of the hypothesized ``up'' and ``dn'' quarks determined by the CBM are 237.31 MeV and 42.392 MeV respectively. These new quarks in addition to a lepton of 7.4 MeV make up one of the missing generations. The details of this new particle physics model can be found at the web site: checkerboard.dnsalias.net. The only areas were this theory conflicts with existing dogma is in the value of the mass of the Top quark. The particle found at Fermi Lab must be some sort of composite particle containing Top quarks.

Physical-depth architectural requirements for generating universal photonic cluster states

Science.gov (United States)

Morley-Short, Sam; Bartolucci, Sara; Gimeno-Segovia, Mercedes; Shadbolt, Pete; Cable, Hugo; Rudolph, Terry

2018-01-01

Most leading proposals for linear-optical quantum computing (LOQC) use cluster states, which act as a universal resource for measurement-based (one-way) quantum computation. In ballistic approaches to LOQC, cluster states are generated passively from small entangled resource states using so-called fusion operations. Results from percolation theory have previously been used to argue that universal cluster states can be generated in the ballistic approach using schemes which exceed the critical threshold for percolation, but these results consider cluster states with unbounded size. Here we consider how successful percolation can be maintained using a physical architecture with fixed physical depth, assuming that the cluster state is continuously generated and measured, and therefore that only a finite portion of it is visible at any one point in time. We show that universal LOQC can be implemented using a constant-size device with modest physical depth, and that percolation can be exploited using simple pathfinding strategies without the need for high-complexity algorithms.

Adiabatic density perturbations and matter generation from the minimal supersymmetric standard model.

Science.gov (United States)

Enqvist, Kari; Kasuya, Shinta; Mazumdar, Anupam

2003-03-07

We propose that the inflaton is coupled to ordinary matter only gravitationally and that it decays into a completely hidden sector. In this scenario both baryonic and dark matter originate from the decay of a flat direction of the minimal supersymmetric standard model, which is shown to generate the desired adiabatic perturbation spectrum via the curvaton mechanism. The requirement that the energy density along the flat direction dominates over the inflaton decay products fixes the flat direction almost uniquely. The present residual energy density in the hidden sector is typically shown to be small.

Collimated fast electron beam generation in critical density plasma

Energy Technology Data Exchange (ETDEWEB)

Iwawaki, T., E-mail: iwawaki-t@eie.eng.osaka-u.ac.jp; Habara, H.; Morita, K.; Tanaka, K. A. [Graduate School of Engineering, Osaka University, 2-1, Yamada-oka, Suita, Osaka 565-0871 (Japan); Baton, S.; Fuchs, J.; Chen, S. [LULI, CNRS-Ecole Polytechnique-Université Pierre et Marie Curie-CEA, 91128 Palaiseau (France); Nakatsutsumi, M. [LULI, CNRS-Ecole Polytechnique-Université Pierre et Marie Curie-CEA, 91128 Palaiseau (France); European X-Ray Free-Electron Laser Facility (XFEL) GmbH (Germany); Rousseaux, C. [CEA, DAM, DIF, F-91297 Arpajon (France); Filippi, F. [La SAPIENZA, University of Rome, Dip. SBAI, 00161 Rome (Italy); Nazarov, W. [School of Chemistry, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9ST, Scotland (United Kingdom)

2014-11-15

Significantly collimated fast electron beam with a divergence angle 10° (FWHM) is observed when an ultra-intense laser pulse (I = 10{sup 14 }W/cm{sup 2}, 300 fs) irradiates a uniform critical density plasma. The uniform plasma is created through the ionization of an ultra-low density (5 mg/c.c.) plastic foam by X-ray burst from the interaction of intense laser (I = 10{sup 14 }W/cm{sup 2}, 600 ps) with a thin Cu foil. 2D Particle-In-Cell (PIC) simulation well reproduces the collimated electron beam with a strong magnetic field in the region of the laser pulse propagation. To understand the physical mechanism of the collimation, we calculate energetic electron motion in the magnetic field obtained from the 2D PIC simulation. As the results, the strong magnetic field (300 MG) collimates electrons with energy over a few MeV. This collimation mechanism may attract attention in many applications such as electron acceleration, electron microscope and fast ignition of laser fusion.

Electron beam manipulation, injection and acceleration in plasma wakefield accelerators by optically generated plasma density spikes

Energy Technology Data Exchange (ETDEWEB)

Wittig, Georg; Karger, Oliver S.; Knetsch, Alexander [Institute of Experimental Physics, University of Hamburg, 22761 Hamburg (Germany); Xi, Yunfeng; Deng, Aihua; Rosenzweig, James B. [Particle Beam Physics Laboratory, UCLA, Los Angeles, CA 90095 (United States); Bruhwiler, David L. [RadiaSoft LLC, Boulder, CO 80304 (United States); RadiaBeam Technologies LLC (United States); Smith, Jonathan [Tech-X UK Ltd, Daresbury, Cheshire WA4 4FS (United Kingdom); Sheng, Zheng-Ming; Jaroszynski, Dino A.; Manahan, Grace G. [Physics Department, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Hidding, Bernhard [Institute of Experimental Physics, University of Hamburg, 22761 Hamburg (Germany); Physics Department, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

2016-09-01

We discuss considerations regarding a novel and robust scheme for optically triggered electron bunch generation in plasma wakefield accelerators [1]. In this technique, a transversely propagating focused laser pulse ignites a quasi-stationary plasma column before the arrival of the plasma wake. This localized plasma density enhancement or optical “plasma torch” distorts the blowout during the arrival of the electron drive bunch and modifies the electron trajectories, resulting in controlled injection. By changing the gas density, and the laser pulse parameters such as beam waist and intensity, and by moving the focal point of the laser pulse, the shape of the plasma torch, and therefore the generated trailing beam, can be tuned easily. The proposed method is much more flexible and faster in generating gas density transitions when compared to hydrodynamics-based methods, and it accommodates experimentalists needs as it is a purely optical process and straightforward to implement.

Frontiers in pulse-power-based high energy density plasma physics and its applications

International Nuclear Information System (INIS)

Horioka, Kazuhiko

2008-03-01

The papers in this volume of report were presented at the Symposium on Frontiers in Pulse-power-based High Energy Density Physics' held by National Institute for Fusion Science. The topics include the present status of high energy density plasma researches, extreme ultraviolet sources, intense radiation sources, high power ion beams, and R and D of related pulse power technologies. The 13 of the presented papers are indexed individually. (J.P.N.)

Random number generators in support of Monte Carlo problems in physics

International Nuclear Information System (INIS)

Dyadkin, I.G.

1993-01-01

The ability to support a modern users' expectations of random number generators to solve problems in physics is analyzed. The capabilities of the newest concepts and the old pseudo-random algorithms are compared. The author is in favor of multiplicative generators. Due to the 64-bit arithmetic of a modern PC, multiplicative generators have a sufficient number of periods (up to 2 62 ) and are quicker to generate and to govern independent sequences for parallel processing. In addition they are able to replicate sub-sequences (without storing their seeds) for each standard trial in any code and to simulate spatial and planar directions and EXP(-x) distributions often needed as ''bricks'' for simulating events in physics. Hundreds of multipliers for multiplicative generators have been tabulated and tested, and the required speeds have been obtained. (author)

A unified dislocation density-dependent physical-based constitutive model for cold metal forming

Science.gov (United States)

Schacht, K.; Motaman, A. H.; Prahl, U.; Bleck, W.

2017-10-01

Dislocation-density-dependent physical-based constitutive models of metal plasticity while are computationally efficient and history-dependent, can accurately account for varying process parameters such as strain, strain rate and temperature; different loading modes such as continuous deformation, creep and relaxation; microscopic metallurgical processes; and varying chemical composition within an alloy family. Since these models are founded on essential phenomena dominating the deformation, they have a larger range of usability and validity. Also, they are suitable for manufacturing chain simulations since they can efficiently compute the cumulative effect of the various manufacturing processes by following the material state through the entire manufacturing chain and also interpass periods and give a realistic prediction of the material behavior and final product properties. In the physical-based constitutive model of cold metal plasticity introduced in this study, physical processes influencing cold and warm plastic deformation in polycrystalline metals are described using physical/metallurgical internal variables such as dislocation density and effective grain size. The evolution of these internal variables are calculated using adequate equations that describe the physical processes dominating the material behavior during cold plastic deformation. For validation, the model is numerically implemented in general implicit isotropic elasto-viscoplasticity algorithm as a user-defined material subroutine (UMAT) in ABAQUS/Standard and used for finite element simulation of upsetting tests and a complete cold forging cycle of case hardenable MnCr steel family.

Moderate energy ions for high energy density physics experiments

International Nuclear Information System (INIS)

Grisham, L.R.

2004-01-01

This paper gives the results of a preliminary exploration of whether moderate energy ions (≅0.3-3 MeV/amu) could be useful as modest-cost drivers for high energy density physics experiments. It is found that if the target thickness is chosen so that the ion beam enters and then leaves the target in the vicinity of the peak of the dE/dX (stopping power) curve, high uniformity of energy deposition may be achievable while also maximizing the amount of energy per beam particle deposited within the target

Perspective: Fifty years of density-functional theory in chemical physics

International Nuclear Information System (INIS)

Becke, Axel D.

2014-01-01

Since its formal inception in 1964–1965, Kohn-Sham density-functional theory (KS-DFT) has become the most popular electronic structure method in computational physics and chemistry. Its popularity stems from its beautifully simple conceptual framework and computational elegance. The rise of KS-DFT in chemical physics began in earnest in the mid 1980s, when crucial developments in its exchange-correlation term gave the theory predictive power competitive with well-developed wave-function methods. Today KS-DFT finds itself under increasing pressure to deliver higher and higher accuracy and to adapt to ever more challenging problems. If we are not mindful, however, these pressures may submerge the theory in the wave-function sea. KS-DFT might be lost. I am hopeful the Kohn-Sham philosophical, theoretical, and computational framework can be preserved. This Perspective outlines the history, basic concepts, and present status of KS-DFT in chemical physics, and offers suggestions for its future development

Perspective: Fifty years of density-functional theory in chemical physics

Energy Technology Data Exchange (ETDEWEB)

Becke, Axel D., E-mail: axel.becke@dal.ca [Department of Chemistry, Dalhousie University, 6274 Coburg Rd., P.O. Box 15000, Halifax, Nova Scotia B3H 4R2 (Canada)

2014-05-14

Since its formal inception in 1964–1965, Kohn-Sham density-functional theory (KS-DFT) has become the most popular electronic structure method in computational physics and chemistry. Its popularity stems from its beautifully simple conceptual framework and computational elegance. The rise of KS-DFT in chemical physics began in earnest in the mid 1980s, when crucial developments in its exchange-correlation term gave the theory predictive power competitive with well-developed wave-function methods. Today KS-DFT finds itself under increasing pressure to deliver higher and higher accuracy and to adapt to ever more challenging problems. If we are not mindful, however, these pressures may submerge the theory in the wave-function sea. KS-DFT might be lost. I am hopeful the Kohn-Sham philosophical, theoretical, and computational framework can be preserved. This Perspective outlines the history, basic concepts, and present status of KS-DFT in chemical physics, and offers suggestions for its future development.

Generating physical symptoms from visual cues: An experimental study.

Science.gov (United States)

Ogden, Jane; Zoukas, Serafim

2009-12-01

This experimental study explored whether the physical symptoms of cold, pain and itchiness could be generated by visual cues, whether they varied in the ease with which they could be generated and whether they were related to negative affect. Participants were randomly allocated by group to watch one of three videos relating to cold (e.g. ice, snow, wind), pain (e.g. sporting injuries, tattoos) or itchiness (e.g. head lice, scratching). They then rated their self-reported symptoms of cold, pain and itchiness as well as their negative affect (depression and anxiety). The researcher recorded their observed behaviour relating to these symptoms. The results showed that the interventions were successful and that all three symptoms could be generated by the visual cues in terms of both self-report and observed behaviour. In addition, the pain video generated higher levels of anxiety and depression than the other two videos. Further, the degree of itchiness was related to the degree of anxiety. This symptom onset process also showed variability between symptoms with self-reported cold symptoms being greater than either pain or itchy symptoms. The results show that physical symptoms can be generated by visual cues indicating that psychological factors are not only involved in symptom perception but also in symptom onset.

Megagauss field generation for high-energy-density plasma science experiments

International Nuclear Information System (INIS)

Rovang, Dean Curtis; Struve, Kenneth William; Porter, John Larry Jr.

2008-01-01

There is a need to generate magnetic fields both above and below 1 megagauss (100 T) with compact generators for laser-plasma experiments in the Beamlet and Petawatt test chambers for focused research on fundamental properties of high energy density magnetic plasmas. Some of the important topics that could be addressed with such a capability are magnetic field diffusion, particle confinement, plasma instabilities, spectroscopic diagnostic development, material properties, flux compression, and alternate confinement schemes, all of which could directly support experiments on Z. This report summarizes a two-month study to develop preliminary designs of magnetic field generators for three design regimes. These are, (1) a design for a relatively low-field (10 to 50 T), compact generator for modest volumes (1 to 10 cm3), (2) a high-field (50 to 200 T) design for smaller volumes (10 to 100 mm3), and (3) an extreme field (greater than 600 T) design that uses flux compression. These designs rely on existing Sandia pulsed-power expertise and equipment, and address issues of magnetic field scaling with capacitor bank design and field inductance, vacuum interface, and trade-offs between inductance and coil designs

V-I characteristics of a coreless ironless electric generator in a closed-circuit mode for low wind density power generation

Science.gov (United States)

Razali, Akhtar; Rahman, Fadhlur; Leong, Yap Wee; Razali Hanipah, Mohd; Azri Hizami, Mohd

2018-04-01

This research deals with removal of ironcore lamination in electric generator to eliminate cog torque. A confinement technique is proposed to confine and focus magnetic flux by introducing opposing permanent magnets arrangement. The generator was fabricated and experimentally validated to qualify its loaded characteristics. The rotational torque and power output are measured and efficiency is then analyzed. At 100Ω load, the generator power output increased with the increased of rotational speed. Nearly 78% of efficiency was achieved when the generator was rotated at 250rpm. At this speed, the generator produced RMS voltage of 81VAC. Torque required to rotate the generator was found to be 3.2Nm. The slight increment of mechanical torque to spin the generator was due to the counter electromotive force (CEMF) existed in the copper windings. However, the torque required is still lower by nearly 30% than conventional AFPM generator. It is there concluded that this generator is suitable to be used for low wind density power generation application.

Electromagnetic-implosion generation of pulsed high energy density plasma

International Nuclear Information System (INIS)

Baker, W.L.; Broderick, N.F.; Degnan, J.H.; Hussey, T.W.; Kiuttu, G.F.; Kloc, D.A.; Reinovsky, R.E.

1983-01-01

This chapter reports on the experimental and theoretical investigation of the generation of pulsed high-energy-density plasmas by electromagnetic implosion of cylindrical foils (i.e., imploding liners or hollow Z-pinches) at the Air Force Weapons Laboratory. Presents a comparison of experimental data with one-dimensional MHD and two-dimensional calculations. Points out that the study is distinct from other imploding liner efforts in that the approach is to produce a hot, dense plasma from the imploded liner itself, rather than to compress a magnetic-field-performed plasma mixture. The goal is to produce an intense laboratory pulsed X-ray source

Physical properties of Martian meteorites: Porosity and density measurements

Science.gov (United States)

Coulson, Ian M.; Beech, Martin; Nie, Wenshuang

Martian meteorites are fragments of the Martian crust. These samples represent igneous rocks, much like basalt. As such, many laboratory techniques designed for the study of Earth materials have been applied to these meteorites. Despite numerous studies of Martian meteorites, little data exists on their basic structural characteristics, such as porosity or density, information that is important in interpreting their origin, shock modification, and cosmic ray exposure history. Analysis of these meteorites provides both insight into the various lithologies present as well as the impact history of the planet's surface. We present new data relating to the physical characteristics of twelve Martian meteorites. Porosity was determined via a combination of scanning electron microscope (SEM) imagery/image analysis and helium pycnometry, coupled with a modified Archimedean method for bulk density measurements. Our results show a range in porosity and density values and that porosity tends to increase toward the edge of the sample. Preliminary interpretation of the data demonstrates good agreement between porosity measured at 100× and 300× magnification for the shergottite group, while others exhibit more variability. In comparison with the limited existing data for Martian meteorites we find fairly good agreement, although our porosity values typically lie at the low end of published values. Surprisingly, despite the increased data set, there is little by way of correlation between either porosity or density with parameters such as shock effect or terrestrial residency. Further data collection on additional meteorite samples is required before more definitive statements can be made concerning the validity of these observations.

Density fractions versus size separates: does physical fractionation isolate functional soil compartments?

Directory of Open Access Journals (Sweden)

C. Moni

2012-12-01

Full Text Available Physical fractionation is a widely used methodology to study soil organic matter (SOM dynamics, but concerns have been raised that the available fractionation methods do not well describe functional SOM pools. In this study we explore whether physical fractionation techniques isolate soil compartments in a meaningful and functionally relevant way for the investigation of litter-derived nitrogen dynamics at the decadal timescale. We do so by performing aggregate density fractionation (ADF and particle size-density fractionation (PSDF on mineral soil samples from two European beech forests a decade after application of ¹⁵N labelled litter.

Both density and size-based fractionation methods suggested that litter-derived nitrogen became increasingly associated with the mineral phase as decomposition progressed, within aggregates and onto mineral surfaces. However, scientists investigating specific aspects of litter-derived nitrogen dynamics are pointed towards ADF when adsorption and aggregation processes are of interest, whereas PSDF is the superior tool to research the fate of particulate organic matter (POM.

Some methodological caveats were observed mainly for the PSDF procedure, the most important one being that fine fractions isolated after sonication can not be linked to any defined decomposition pathway or protective mechanism. This also implies that historical assumptions about the "adsorbed" state of carbon associated with fine fractions need to be re-evaluated. Finally, this work demonstrates that establishing a comprehensive picture of whole soil OM dynamics requires a combination of both methodologies and we offer a suggestion for an efficient combination of the density and size-based approaches.

US Heavy Ion Beam Research for Energy Density Physics Applications and Fusion

International Nuclear Information System (INIS)

Davidson, R.C.; Logan, B.G.; Barnard, J.J.; Bieniosek, F.M.; Briggs, R.J.; Callahan D.A.; Kireeff Covo, M.; Celata, C.M.; Cohen, R.H.; Coleman, J.E.; Debonnel, C.S.; Grote, D.P.; Efthimiom, P.C.; Eylon, S.; Friedman, A.; Gilson, E.P.; Grisham, L.R.; Henestroza, E.; Kaganovich, I.D.; Kwan, J.W.; Lee, E.P.; Lee, W.W.; Leitner, M.; Lund, S.M.; Meier, W.R.; Molvik, A.W.; Olson, C.L.; Penn, G.E.; Qin, H.; Roy, P.K.; Rose, D.V.; Sefkow, A.; Seidl, P.A.; Sharp, W.M.; Startsev, E.A.; Tabak, M.; Thoma, C.; Vay, J-L; Wadron, W.L.; Wurtele, J.S.; Welch, D.R.; Westenskow, G.A.; Yu, S.S.

2005-01-01

Key scientific results from recent experiments, modeling tools, and heavy ion accelerator research are summarized that explore ways to investigate the properties of high energy density matter in heavy-ion-driven targets, in particular, strongly-coupled plasmas at 0.01 to 0.1 times solid density for studies of warm dense matter, which is a frontier area in high energy density physics. Pursuit of these near-term objectives has resulted in many innovations that will ultimately benefit heavy ion inertial fusion energy. These include: neutralized ion beam compression and focusing, which hold the promise of greatly improving the stage between the accelerator and the target chamber in a fusion power plant; and the Pulse Line Ion Accelerator (PLIA), which may lead to compact, low-cost modular linac drivers

Open circuit V-I characteristics of a coreless ironless electric generator for low density wind power generation

Science.gov (United States)

Razali, Akhtar; Rahman, Fadhlur; Azlan, Syaiful; Razali Hanipah, Mohd; Azri Hizami, Mohd

2018-04-01

Cogging is an attraction of magnetism between permanent magnets and soft ironcore lamination in a conventional electric ironcore generator. The presence of cog in the generator is seen somehow restricted the application of the generator in an application where low rotational torque is required. Cog torque requires an additional input power to overcome, hence became one of the power loss sources. With the increasing of power output, the cogging is also proportionally increased. This leads to the increasing of the supplied power of the driver motor to overcome the cog. Therefore, this research is embarked to study fundamentally about the possibility of removing ironcore lamination in an electric generator. This research deals with removal of ironcore lamination in electric generator to eliminate cog torque. A confinement technique is proposed to confine and focus magnetic flux by introducing opposing permanent magnets arrangement. The concept is then fabricated and experimentally validated to qualify its no-load characteristics. The rotational torque and power output are measured and efficiency is then analyzed. Results indicated that the generator produced RMS voltage of 416VAC at rotational speed of 1762 RPM. Torque required to rotate the generator was at 2Nm for various rotational speed. The generator has shown 30% lesser rotational torque compared to the conventional ironcore type generator due to the absent of cogging torque in the system. Lesser rotational torque required to rotate has made this type of generator has a potential to be used for low wind density wind turbine application.

High density data storage principle, technology, and materials

CERN Document Server

Zhu, Daoben

2009-01-01

The explosive increase in information and the miniaturization of electronic devices demand new recording technologies and materials that combine high density, fast response, long retention time and rewriting capability. As predicted, the current silicon-based computer circuits are reaching their physical limits. Further miniaturization of the electronic components and increase in data storage density are vital for the next generation of IT equipment such as ultra high-speed mobile computing, communication devices and sophisticated sensors. This original book presents a comprehensive introduction to the significant research achievements on high-density data storage from the aspects of recording mechanisms, materials and fabrication technologies, which are promising for overcoming the physical limits of current data storage systems. The book serves as an useful guide for the development of optimized materials, technologies and device structures for future information storage, and will lead readers to the fascin...

Method and means for a spatial and temporal probe for laser-generated plumes based on density gradients

Science.gov (United States)

Yeung, E.S.; Chen, G.

1990-05-01

A method and means are disclosed for a spatial and temporal probe for laser generated plumes based on density gradients includes generation of a plume of vaporized material from a surface by an energy source. The probe laser beam is positioned so that the plume passes through the probe laser beam. Movement of the probe laser beam caused by refraction from the density gradient of the plume is monitored. Spatial and temporal information, correlated to one another, is then derived. 15 figs.

Radiative corrections and Monte Carlo generators for physics at flavor factories

Directory of Open Access Journals (Sweden)

Montagna Guido

2016-01-01

Full Text Available I review the state of the art of precision calculations and related Monte Carlo generators used in physics at flavor factories. The review describes the tools relevant for the measurement of the hadron production cross section (via radiative return, energy scan and in γγ scattering, luminosity monitoring, searches for new physics and physics of the τ lepton.

High-power density miniscale power generation and energy harvesting systems

International Nuclear Information System (INIS)

Lyshevski, Sergey Edward

2011-01-01

This paper reports design, analysis, evaluations and characterization of miniscale self-sustained power generation systems. Our ultimate objective is to guarantee highly-efficient mechanical-to-electrical energy conversion, ensure premier wind- or hydro-energy harvesting capabilities, enable electric machinery and power electronics solutions, stabilize output voltage, etc. By performing the advanced scalable power generation system design, we enable miniscale energy sources and energy harvesting technologies. The proposed systems integrate: (1) turbine which rotates a radial- or axial-topology permanent-magnet synchronous generator at variable angular velocity depending on flow rate, speed and load, and, (2) power electronic module with controllable rectifier, soft-switching converter and energy storage stages. These scalable energy systems can be utilized as miniscale auxiliary and self-sustained power units in various applications, such as, aerospace, automotive, biotechnology, biomedical, and marine. The proposed systems uniquely suit various submersible and harsh environment applications. Due to operation in dynamic rapidly-changing envelopes (variable speed, load changes, etc.), sound solutions are researched, proposed and verified. We focus on enabling system organizations utilizing advanced developments for various components, such as generators, converters, and energy storage. Basic, applied and experimental findings are reported. The prototypes of integrated power generation systems were tested, characterized and evaluated. It is documented that high-power density, high efficiency, robustness and other enabling capabilities are achieved. The results and solutions are scalable from micro (∼100 μW) to medium (∼100 kW) and heavy-duty (sub-megawatt) auxiliary and power systems.

Thermodynamic, energy efficiency, and power density analysis of reverse electrodialysis power generation with natural salinity gradients

NARCIS (Netherlands)

Yip, N.Y.; Vermaas, D.A.; Nijmeijer, K.; Elimelech, M.

2014-01-01

Reverse electrodialysis (RED) can harness the Gibbs free energy of mixing when fresh river water flows into the sea for sustainable power generation. In this study, we carry out a thermodynamic and energy efficiency analysis of RED power generation, and assess the membrane power density. First, we

Use of a high density lead glass tubing projection chamber in positron emission tomography and in high energy physics

International Nuclear Information System (INIS)

Conti, M.; Guerra, A.D.; Habel, R.; Mulera, T.; Perez-Mendez, V.; Schwartz, G.

1985-10-01

We describe the principle of operation of a high density Projection Chamber, in which the converter/radiator and drift field shaping structures are combined in the form of high density (5 to 6 g/cm 3 ) lead glass tubing. The main applications of this type of detector to Medical Physics (Positron Emission Tomography) and High Energy Physics (Electromagnetic Calorimetry) are discussed

High energy density and extreme field physics in the transparent-overdense regime

Energy Technology Data Exchange (ETDEWEB)

Hegelich, Bjorn Manuel [Los Alamos National Laboratory; Yin, Kin [Los Alamos National Laboratory; Albright, Brian J [Los Alamos National Laboratory; Bowers, Kevin J [Los Alamos National Laboratory; Gautier, C [Los Alamos National Laboratory; Huang, C [Los Alamos National Laboratory; Jung, D [Los Alamos National Laboratory; Letzring, S [Los Alamos National Laboratory; Palaniyappan, S [Los Alamos National Laboratory; Shah, R [Los Alamos National Laboratory; Wu, H [Los Alamos National Laboratory; Fernandez, J. C. [Los Alamos National Laboratory; Dromey, B [QUEENS UNIV BELFAST; Henig, A [LUDWIG-MAXIMILLAN-UNIV MUNCHEN; Horlein, R [LUDWIG-MAXIMILLAN-UNIV MUNCHEN; Kefer, D. [LUDWIG-MAXIMILLAN-UNIV MUNCHEN; Tajima, T [LUDWIG-MAXIMILIN-UNIV MUNCHEN; Yan, X [QUEENS UNIV BELFAST; Habs, D [LUDWIG-MAXIMILIAN-UNIV MUNCHEN

2011-01-31

Conclusions of this report are: (1) high harmonics generated on solid surfaces are a very versatile source of intense coherent XUV radiation; (2) high harmonics can be used to probe and monitor the interaction of intense femtosecond laser pulses with nm-scale foil targets; (3) direct measurement of target density during relativistic interaction; (4) high harmonics generated with PW-scale short-pulse lasers could serve as unique backlighting sources for a wide range experiments; and (5) Trident can be a test bed to develop such experiments and the required instrumentation.

Generating physical symptoms from visual cues: An experimental study

OpenAIRE

Ogden, J; Zoukas, S

2010-01-01

This experimental study explored whether the physical symptoms of cold, pain and itchiness could be generated by visual cues, whether they varied in the ease with which they could be generated and whether they were related to negative affect. Participants were randomly allocated by group to watch one of three videos relating to cold (e.g. ice, snow, wind), pain (e.g. sporting injuries, tattoos) or itchiness (e.g. head lice, scratching). They then rated their self-reported symptoms of cold, pa...

Note: A high-energy-density Tesla-type pulse generator with novel insulating oil

Science.gov (United States)

Liu, Sheng; Su, Jiancang; Fan, Xuliang

2017-09-01

A 10-GW high-energy-density Tesla-type pulse generator is developed with an improved insulating liquid based on a modified Tesla pulser—TPG700, of which the pulse forming line (PFL) is filled with novel insulating oil instead of transformer oil. Properties of insulating oil determining the stored energy density of the PFL are analyzed, and a criterion for appropriate oil is proposed. Midel 7131 is chosen as an application example. The results of insulating property experiment under tens-of-microsecond pulse charging demonstrate that the insulation capability of Midel 7131 is better than that of KI45X transformer oil. The application test in Tesla pulser TPG700 shows that the output power is increased to 10.5 GW with Midel 7131. The output energy density of TPG700 increases for about 60% with Midel 7131.

Physical properties of five grain dust types.

Science.gov (United States)

Parnell, C B; Jones, D D; Rutherford, R D; Goforth, K J

1986-01-01

Physical properties of grain dust derived from five grain types (soybean, rice, corn, wheat, and sorghum) were measured and reported. The grain dusts were obtained from dust collection systems of terminal grain handling facilities and were assumed to be representative of grain dust generated during the handling process. The physical properties reported were as follows: particle size distributions and surface area measurements using a Coulter Counter Model TAII; percent dust fractions less than 100 micron of whole dust; bulk density; particle density; and ash content. PMID:3709482

Relationship between neural rhythm generation disorders and physical disabilities in Parkinson's disease patients' walking.

Science.gov (United States)

Ota, Leo; Uchitomi, Hirotaka; Ogawa, Ken-ichiro; Orimo, Satoshi; Miyake, Yoshihiro

2014-01-01

Walking is generated by the interaction between neural rhythmic and physical activities. In fact, Parkinson's disease (PD), which is an example of disease, causes not only neural rhythm generation disorders but also physical disabilities. However, the relationship between neural rhythm generation disorders and physical disabilities has not been determined. The aim of this study was to identify the mechanism of gait rhythm generation. In former research, neural rhythm generation disorders in PD patients' walking were characterized by stride intervals, which are more variable and fluctuate randomly. The variability and fluctuation property were quantified using the coefficient of variation (CV) and scaling exponent α. Conversely, because walking is a dynamic process, postural reflex disorder (PRD) is considered the best way to estimate physical disabilities in walking. Therefore, we classified the severity of PRD using CV and α. Specifically, PD patients and healthy elderly were classified into three groups: no-PRD, mild-PRD, and obvious-PRD. We compared the contributions of CV and α to the accuracy of this classification. In this study, 45 PD patients and 17 healthy elderly people walked 200 m. The severity of PRD was determined using the modified Hoehn-Yahr scale (mH-Y). People with mH-Y scores of 2.5 and 3 had mild-PRD and obvious-PRD, respectively. As a result, CV differentiated no-PRD from PRD, indicating the correlation between CV and PRD. Considering that PRD is independent of neural rhythm generation, this result suggests the existence of feedback process from physical activities to neural rhythmic activities. Moreover, α differentiated obvious-PRD from mild-PRD. Considering α reflects the intensity of interaction between factors, this result suggests the change of the interaction. Therefore, the interaction between neural rhythmic and physical activities is thought to plays an important role for gait rhythm generation. These characteristics have

High-power density miniscale power generation and energy harvesting systems

Energy Technology Data Exchange (ETDEWEB)

Lyshevski, Sergey Edward [Department of Electrical and Microelectronics Engineering, Rochester Institute of Technology, Rochester, NY 14623-5603 (United States)

2011-01-15

This paper reports design, analysis, evaluations and characterization of miniscale self-sustained power generation systems. Our ultimate objective is to guarantee highly-efficient mechanical-to-electrical energy conversion, ensure premier wind- or hydro-energy harvesting capabilities, enable electric machinery and power electronics solutions, stabilize output voltage, etc. By performing the advanced scalable power generation system design, we enable miniscale energy sources and energy harvesting technologies. The proposed systems integrate: (1) turbine which rotates a radial- or axial-topology permanent-magnet synchronous generator at variable angular velocity depending on flow rate, speed and load, and, (2) power electronic module with controllable rectifier, soft-switching converter and energy storage stages. These scalable energy systems can be utilized as miniscale auxiliary and self-sustained power units in various applications, such as, aerospace, automotive, biotechnology, biomedical, and marine. The proposed systems uniquely suit various submersible and harsh environment applications. Due to operation in dynamic rapidly-changing envelopes (variable speed, load changes, etc.), sound solutions are researched, proposed and verified. We focus on enabling system organizations utilizing advanced developments for various components, such as generators, converters, and energy storage. Basic, applied and experimental findings are reported. The prototypes of integrated power generation systems were tested, characterized and evaluated. It is documented that high-power density, high efficiency, robustness and other enabling capabilities are achieved. The results and solutions are scalable from micro ({proportional_to}100 {mu}W) to medium ({proportional_to}100 kW) and heavy-duty (sub-megawatt) auxiliary and power systems. (author)

Physical Modeling of microtubule force generation and self-organization

NARCIS (Netherlands)

Tanase, C.

2004-01-01

Biological systems are complex heterogeneous and far from equilibrium systems. The fundamental questions posed by the physics of such systems are what the force generation mechanisms are, and how energy is processed and distributed among the components inside them. In answering these questions we

Physics and applications of high energy density plasmas. Extreme state driven by pulsed electromagnetic energy

International Nuclear Information System (INIS)

Horioka, Kazuhiko

2002-06-01

The papers presented at the symposium on ''Physics and application of high energy density plasmas, held December 20-21, 2001 at NIFS'' are collected in this proceedings. The topics covered in the meeting include dense z-pinches, plasma focus, intense charged particle beams, intense radiation sources, discharge pumped X-ray lasers, their diagnostics, and applications of them. The papers reflect the present status and trends in the research field of high energy density plasmas. (author)

Level densities in nuclear physics

International Nuclear Information System (INIS)

Beckerman, M.

1978-01-01

In the independent-particle model nucleons move independently in a central potential. There is a well-defined set of single- particle orbitals, each nucleon occupies one of these orbitals subject to Fermi statistics, and the total energy of the nucleus is equal to the sum of the energies of the individual nucleons. The basic question is the range of validity of this Fermi gas description and, in particular, the roles of the residual interactions and collective modes. A detailed examination of experimental level densities in light-mass system is given to provide some insight into these questions. Level densities over the first 10 MeV or so in excitation energy as deduced from neutron and proton resonances data and from spectra of low-lying bound levels are discussed. To exhibit some of the salient features of these data comparisons to independent-particle (shell) model calculations are presented. Shell structure is predicted to manifest itself through discontinuities in the single-particle level density at the Fermi energy and through variatons in the occupancy of the valence orbitals. These predictions are examined through combinatorial calculations performed with the Grover [Phys. Rev., 157, 832(1967), 185 1303(1969)] odometer method. Before the discussion of the experimenta results, statistical mechanical level densities for spherical nuclei are reviewed. After consideration of deformed nuclei, the conclusions resulting from this work are drawn. 7 figures, 3 tables

Analysis of the Effect of Electron Density Perturbations Generated by Gravity Waves on HF Communication Links

Science.gov (United States)

Fagre, M.; Elias, A. G.; Chum, J.; Cabrera, M. A.

2017-12-01

In the present work, ray tracing of high frequency (HF) signals in ionospheric disturbed conditions is analyzed, particularly in the presence of electron density perturbations generated by gravity waves (GWs). The three-dimensional numerical ray tracing code by Jones and Stephenson, based on Hamilton's equations, which is commonly used to study radio propagation through the ionosphere, is used. An electron density perturbation model is implemented to this code based upon the consideration of atmospheric GWs generated at a height of 150 km in the thermosphere and propagating up into the ionosphere. The motion of the neutral gas at these altitudes induces disturbances in the background plasma which affects HF signals propagation. To obtain a realistic model of GWs in order to analyze the propagation and dispersion characteristics, a GW ray tracing method with kinematic viscosity and thermal diffusivity was applied. The IRI-2012, HWM14 and NRLMSISE-00 models were incorporated to assess electron density, wind velocities, neutral temperature and total mass density needed for the ray tracing codes. Preliminary results of gravity wave effects on ground range and reflection height are presented for low-mid latitude ionosphere.

Generation of second-harmonic radiations of a self-focusing laser from a plasma with density-transition

International Nuclear Information System (INIS)

Kant, Niti; Gupta, Devki Nandan; Suk, Hyyong

2011-01-01

A Gaussian laser-beam resonantly generates a second-harmonic wave in a plasma in the presence of a wiggler magnetic-field of suitable period. The self-focusing of the fundamental pulse enhances the intensity of the second-harmonic pulse. An introduction of an upward plasma-density ramp strongly enhances the self-focusing of the fundamental laser pulse. The laser pulse attains a minimum spot size and propagates up to several Rayleigh lengths without divergence. Due to the strong self-focusing of the fundamental laser pulse, the second-harmonic intensity enhances significantly. A considerable enhancement of the intensity of the second-harmonic is observed from the proposed mechanism. -- Highlights: → An upward plasma-density ramp is very important for laser propagation in plasmas. → As the plasma density increases, effect of self-focusing becomes stronger. → We utilize this self-focused laser to generate second-harmonic radiations. → The self-focusing laser enhances the intensity of the second-harmonic pulse.

Generation of second-harmonic radiations of a self-focusing laser from a plasma with density-transition

Energy Technology Data Exchange (ETDEWEB)

Kant, Niti [Department of Physics, Lovely Professional University, Phagwara 144 402, Punjab (India); Gupta, Devki Nandan, E-mail: dngupta@physics.du.ac.in [Department of Physics and Astrophysics, University of Delhi, Delhi 110 007 (India); Suk, Hyyong [Advanced Photonics Research Institute (APRI) and Graduate Program of Photonics and Applied Physics, Gwangju Institute of Science and Technology, Gwangju 500 712 (Korea, Republic of)

2011-08-15

A Gaussian laser-beam resonantly generates a second-harmonic wave in a plasma in the presence of a wiggler magnetic-field of suitable period. The self-focusing of the fundamental pulse enhances the intensity of the second-harmonic pulse. An introduction of an upward plasma-density ramp strongly enhances the self-focusing of the fundamental laser pulse. The laser pulse attains a minimum spot size and propagates up to several Rayleigh lengths without divergence. Due to the strong self-focusing of the fundamental laser pulse, the second-harmonic intensity enhances significantly. A considerable enhancement of the intensity of the second-harmonic is observed from the proposed mechanism. -- Highlights: → An upward plasma-density ramp is very important for laser propagation in plasmas. → As the plasma density increases, effect of self-focusing becomes stronger. → We utilize this self-focused laser to generate second-harmonic radiations. → The self-focusing laser enhances the intensity of the second-harmonic pulse.

The physics of non-ideal plasma

CERN Document Server

Fortov, Vladimir E

2000-01-01

This book is devoted to the physical properties of nonideal plasma which is compressed so strongly that the effects of interparticle interactions govern the plasma behavior. The interest in this plasma was generated by the development of modern technologies and facilities whose operations were based on high densities of energy. In this volume, the methods of nonideal plasma generation and diagnostics are considered. The experimental results are given and the main theoretical models of nonideal plasma state are discussed. The problems of thermodynamics, electro-physics, optics and dynamic stabi

Temporal evolution of plasma density in femtosecond light filaments

International Nuclear Information System (INIS)

Wang Haitao; Fan Chengyu; Shen Hong; Qiao Chunhong; Zhang Jinghui; Zhang Pengfei; Ma Huimin; Xu Huiling

2012-01-01

By using a legible and comprehensive physical model describing the generation and evolvement of ion densities in the plasma channel induced by intense femtosecond laser pulse, the work studied the temporal evolution of the plasma densities in femtosecond light filaments. It shows that the contribution of the ionization of oxygen and nitrogen molecules to the total electron densities varies much for different laser pulse shapes, and the pulse shapes have more effects on the lifetime of the higher density plasma. It is necessary to control the pulse shape for efficient using of the plasma channel. Pulses of long duration and short wavelength can obtain a plasma channel with higher electron density, but the channel lifetime thoroughly depends on the later evolution of the self-guided channel. (authors)

Large Hadron Collider at CERN: Beams generating high-energy-density matter.

Science.gov (United States)

Tahir, N A; Schmidt, R; Shutov, A; Lomonosov, I V; Piriz, A R; Hoffmann, D H H; Deutsch, C; Fortov, V E

2009-04-01

This paper presents numerical simulations that have been carried out to study the thermodynamic and hydrodynamic responses of a solid copper cylindrical target that is facially irradiated along the axis by one of the two Large Hadron Collider (LHC) 7 TeV/ c proton beams. The energy deposition by protons in solid copper has been calculated using an established particle interaction and Monte Carlo code, FLUKA, which is capable of simulating all components of the particle cascades in matter, up to multi-TeV energies. These data have been used as input to a sophisticated two-dimensional hydrodynamic computer code BIG2 that has been employed to study this problem. The prime purpose of these investigations was to assess the damage caused to the equipment if the entire LHC beam is lost at a single place. The FLUKA calculations show that the energy of protons will be deposited in solid copper within about 1 m assuming constant material parameters. Nevertheless, our hydrodynamic simulations have shown that the energy deposition region will extend to a length of about 35 m over the beam duration. This is due to the fact that first few tens of bunches deposit sufficient energy that leads to high pressure that generates an outgoing radial shock wave. Shock propagation leads to continuous reduction in the density at the target center that allows the protons delivered in subsequent bunches to penetrate deeper and deeper into the target. This phenomenon has also been seen in case of heavy-ion heated targets [N. A. Tahir, A. Kozyreva, P. Spiller, D. H. H. Hoffmann, and A. Shutov, Phys. Rev. E 63, 036407 (2001)]. This effect needs to be considered in the design of a sacrificial beam stopper. These simulations have also shown that the target is severely damaged and is converted into a huge sample of high-energy density (HED) matter. In fact, the inner part of the target is transformed into a strongly coupled plasma with fairly uniform physical conditions. This work, therefore, has

Physics and applications of high energy density plasmas. Extreme state driven by pulsed electromagnetic energy

Energy Technology Data Exchange (ETDEWEB)

Horioka, Kazuhiko (ed.)

2002-06-01

The papers presented at the symposium on ''Physics and application of high energy density plasmas, held December 20-21, 2001 at NIFS'' are collected in this proceedings. The topics covered in the meeting include dense z-pinches, plasma focus, intense charged particle beams, intense radiation sources, discharge pumped X-ray lasers, their diagnostics, and applications of them. The papers reflect the present status and trends in the research field of high energy density plasmas. (author)

Relationships between cone beam CT value and physical density in image guided radiation therapy

International Nuclear Information System (INIS)

Jiang Xiaoqin; Bai Sen; Zhong Renming; Tang Zhiquan; Jiang Qinfeng; Li Tao

2007-01-01

Objective: To evaluate the main factors affecting the relationship between physical density and CT value in cone-beam computed tomography(CBCT) for imaging guided radiation therapy(IGRT) by comparing the CT value in the image from cone-beam scanner and from fan-beam (FBCT) scanner of a reference phantom. Methods: A taking-park reference phantom with a set of tissue equivalent inserts was scanned at different energies different fields of view (FOV) for IGRT-CBCT and FBCT. The CT value of every insert was measured and compared. Results: The position of inserts in phantom, the size of phantom, the FOV of scanner and different energies had more effect on the relationships between physical density and the CT value from IGRT-CBCT than those from the normal FBCT. The higher the energy was, the less effect of the position of inserts in phantom, the size of phantom and the FOV of scanner on CT value, and the poorer density contrast was observed. Conclusion: At present, the CT value of IGRT-CBCT is not in the true HU value since the manufacturer has not corrected its number. Therefore, we are not able to use the CT value of CBCT for dose calculation in TPS. (authors)

The generator coordinate method in nuclear physics

International Nuclear Information System (INIS)

Giraud, B.G.

1981-01-01

The generator coordinate method is introduced as a physical description of a N-body system in a subspace of a reduced number of degrees of freedom. Special attention is placed on the identification of these special, 'collective' degrees of freedom. It is shown in particular that the method has close links with the Born-Oppenheimer approximation and also that considerations of differential geometry are useful in the theory. A set of applications is discussed and in particular the case of nuclear collisions is considered. (Author) [pt

Design and analysis of a direct-drive wind power generator with ultra-high torque density

Science.gov (United States)

Jian, Linni; Shi, Yujun; Wei, Jin; Zheng, Yanchong

2015-05-01

In order to get rid of the nuisances caused by mechanical gearboxes, generators with low rated speed, which can be directly connected to wind turbines, are attracting increasing attention. The purpose of this paper is to propose a new direct-drive wind power generator (DWPG), which can offer ultra-high torque density. First, magnetic gear (MG) is integrated to achieve non-contact torque transmission and speed variation. Second, armature windings are engaged to achieve electromechanical energy conversion. Interior permanent magnet (PM) design on the inner rotor is adopted to boost the torque transmission capability of the integrated MG. Nevertheless, due to lack of back iron on the stator, the proposed generator does not exhibit prominent salient feature, which usually exists in traditional interior PM (IPM) machines. This makes it with good controllability and high power factor as the surface-mounted permanent magnet machines. The performance is analyzed using finite element method. Investigation on the magnetic field harmonics demonstrates that the permanent-magnetic torque offered by the MG can work together with the electromagnetic torque offered by the armature windings to balance the driving torque captured by the wind turbine. This allows the proposed generator having the potential to offer even higher torque density than its integrated MG.

Generation of high-power-density atmospheric pressure plasma with liquid electrodes

International Nuclear Information System (INIS)

Dong Lifang; Mao Zhiguo; Yin Zengqian; Ran Junxia

2004-01-01

We present a method for generating atmospheric pressure plasma using a dielectric barrier discharge reactor with two liquid electrodes. Four distinct kinds of discharge, including stochastic filaments, regular square pattern, glow-like discharge, and Turing stripe pattern, are observed in argon with a flow rate of 9 slm. The electrical and optical characteristics of the device are investigated. Results show that high-power-density atmospheric pressure plasma with high duty ratio in space and time can be obtained. The influence of wall charges on discharge power and duty ratio has been discussed

Learning Physics-based Models in Hydrology under the Framework of Generative Adversarial Networks

Science.gov (United States)

Karpatne, A.; Kumar, V.

2017-12-01

Generative adversarial networks (GANs), that have been highly successful in a number of applications involving large volumes of labeled and unlabeled data such as computer vision, offer huge potential for modeling the dynamics of physical processes that have been traditionally studied using simulations of physics-based models. While conventional physics-based models use labeled samples of input/output variables for model calibration (estimating the right parametric forms of relationships between variables) or data assimilation (identifying the most likely sequence of system states in dynamical systems), there is a greater opportunity to explore the full power of machine learning (ML) methods (e.g, GANs) for studying physical processes currently suffering from large knowledge gaps, e.g. ground-water flow. However, success in this endeavor requires a principled way of combining the strengths of ML methods with physics-based numerical models that are founded on a wealth of scientific knowledge. This is especially important in scientific domains like hydrology where the number of data samples is small (relative to Internet-scale applications such as image recognition where machine learning methods has found great success), and the physical relationships are complex (high-dimensional) and non-stationary. We will present a series of methods for guiding the learning of GANs using physics-based models, e.g., by using the outputs of physics-based models as input data to the generator-learner framework, and by using physics-based models as generators trained using validation data in the adversarial learning framework. These methods are being developed under the broad paradigm of theory-guided data science that we are developing to integrate scientific knowledge with data science methods for accelerating scientific discovery.

High-temperature and high-power-density nanostructured thermoelectric generator for automotive waste heat recovery

International Nuclear Information System (INIS)

Zhang, Yanliang; Cleary, Martin; Wang, Xiaowei; Kempf, Nicholas; Schoensee, Luke; Yang, Jian; Joshi, Giri; Meda, Lakshmikanth

2015-01-01

Highlights: • A thermoelectric generator (TEG) is fabricated using nanostructured half-Heusler materials. • The TE unicouple devices produce superior power density above 5 W/cm"2. • A TEG system with over 1 kW power output is demonstrated by recovering automotive waste heat. - Abstract: Given increasing energy use as well as decreasing fossil fuel sources worldwide, it is no surprise that interest in promoting energy efficiency through waste heat recovery is also increasing. Thermoelectric generators (TEGs) are one of the most promising pathways for waste heat recovery. Despite recent thermoelectric efficiency improvement in nanostructured materials, a variety of challenges have nevertheless resulted in few demonstrations of these materials for large-scale waste heat recovery. Here we demonstrate a high-performance TEG by combining high-efficiency nanostructured bulk materials with a novel direct metal brazing process to increase the device operating temperature. A unicouple device generates a high power density of 5.26 W cm"−"2 with a 500 °C temperature difference between hot and cold sides. A 1 kW TEG system is experimentally demonstrated by recovering the exhaust waste heat from an automotive diesel engine. The TEG system operated with a 2.1% heat-to-electricity efficiency under the average temperature difference of 339 °C between the TEG hot- and cold-side surfaces at a 550 °C exhaust temperature. The high-performance TEG reported here open up opportunities to use TEGs for energy harvesting and power generation applications.

Prediction of density limit disruptions on the J-TEXT tokamak

International Nuclear Information System (INIS)

Wang, S Y; Chen, Z Y; Huang, D W; Tong, R H; Yan, W; Wei, Y N; Ma, T K; Zhang, M; Zhuang, G

2016-01-01

Disruption mitigation is essential for the next generation of tokamaks. The prediction of plasma disruption is the key to disruption mitigation. A neural network combining eight input signals has been developed to predict the density limit disruptions on the J-TEXT tokamak. An optimized training method has been proposed which has improved the prediction performance. The network obtained has been tested on 64 disruption shots and 205 non-disruption shots. A successful alarm rate of 82.8% with a false alarm rate of 12.3% can be achieved at 4.8 ms prior to the current spike of the disruption. It indicates that more physical parameters than the current physical scaling should be considered for predicting the density limit. It was also found that the critical density for disruption can be predicted several tens of milliseconds in advance in most cases. Furthermore, if the network is used for real-time density feedback control, more than 95% of the density limit disruptions can be avoided by setting a proper threshold. (paper)

High-energy-density physics researches based on pulse power technology

International Nuclear Information System (INIS)

Horioka, Kazuhiko; Nakajima, Mitsuo; Kawamura, Tohru; Sasaki, Toru; Kondo, Kotaro; Yano, Yuuri

2006-01-01

Plasmas driven by pulse power device are of interest, concerning the researches on high-energy-density (HED) physics. Dense plasmas are produced using pulse power driven exploding discharges in water. Experimental results show that the wire plasma is tamped and stabilized by the surrounding water and it evolves through a strongly coupled plasma state. A shock-wave-heated, high temperature plasma is produced in a compact pulse power device. Experimental results show that strong shock waves can be produced in the device. In particular, at low initial pressure condition, the shock Mach number reaches 250 and this indicates that the shock heated region is dominated by radiation processes. (author)

U.S. Heavy Ion Beam Research for High Energy Density Physics Applications and Fusion

International Nuclear Information System (INIS)

Davidson, R.C.; Logan, B.G.; Barnard, J.J.; Bieniosek, F.M.; Briggs, R.J.

2005-01-01

Key scientific results from recent experiments, modeling tools, and heavy ion accelerator research are summarized that explore ways to investigate the properties of high energy density matter in heavy-ion-driven targets, in particular, strongly-coupled plasmas at 0.01 to 0.1 times solid density for studies of warm dense matter, which is a frontier area in high energy density physics. Pursuit of these near-term objectives has resulted in many innovations that will ultimately benefit heavy ion inertial fusion energy. These include: neutralized ion beam compression and focusing, which hold the promise of greatly improving the stage between the accelerator and the target chamber in a fusion power plant; and the Pulse Line Ion Accelerator (PLIA), which may lead to compact, low-cost modular linac drivers

MAS Based Distributed Automatic Generation Control for Cyber-Physical Microgrid System

Institute of Scientific and Technical Information of China (English)

Zhongwen Li; Chuanzhi Zang; Peng Zeng; Haibin Yu; Hepeng Li

2016-01-01

The microgrid is a typical cyber-physical microgrid system(CPMS). The physical unconventional distributed generators(DGs) are intermittent and inverter-interfaced which makes them very different to control. The cyber components,such as the embedded computer and communication network,are equipped with DGs, to process and transmit the necessary information for the controllers. In order to ensure system-wide observability, controllability and stabilization for the microgrid,the cyber and physical component need to be integrated. For the physical component of CPMS, the droop-control method is popular as it can be applied in both modes of operation to improve the grid transient performance. Traditional droop control methods have the drawback of the inherent trade-off between power sharing and voltage and frequency regulation. In this paper, the global information(such as the average voltage and the output active power of the microgrid and so on) are acquired distributedly based on multi-agent system(MAS). Based on the global information from cyber components of CPMS, automatic generation control(AGC) and automatic voltage control(AVC)are proposed to deal with the drawback of traditional droop control. Simulation studies in PSCAD demonstrate the effectiveness of the proposed control methods.

MAS Based Distributed Automatic Generation Control for Cyber-Physical Microgrid System

Institute of Scientific and Technical Information of China (English)

Zhongwen Li; Chuanzhi Zang; Peng Zeng; Haibin Yu; Hepeng Li

2016-01-01

The microgrid is a typical cyber-physical micro grid system (CPMS).The physical unconventional distributed generators (DGs) are intermittent and inverter-interfaced which makes them very different to control.The cyber components,such as the embedded computer and communication network,are equipped with DGs,to process and transmit the necessary information for the controllers.In order to ensure system-wide observability,controllability and stabilization for the microgrid,the cyber and physical component need to be integrated.For the physical component of CPMS,the droop-control method is popular as it can be applied in both modes of operation to improve the grid transient performance.Traditional droop control methods have the drawback of the inherent trade-off between power sharing and voltage and frequency regulation.In this paper,the global information (such as the average voltage and the output active power of the microgrid and so on) are acquired distributedly based on multi-agent system (MAS).Based on the global information from cyber components of CPMS,automatic generation control (AGC) and automatic voltage control (AVC) are proposed to deal with the drawback of traditional droop control.Simulation studies in PSCAD demonstrate the effectiveness of the proposed control methods.

Random distance distribution for spherical objects: general theory and applications to physics

International Nuclear Information System (INIS)

Tu Shuju; Fischbach, Ephraim

2002-01-01

A formalism is presented for analytically obtaining the probability density function, P n (s), for the random distance s between two random points in an n-dimensional spherical object of radius R. Our formalism allows P n (s) to be calculated for a spherical n-ball having an arbitrary volume density, and reproduces the well-known results for the case of uniform density. The results find applications in geometric probability, computational science, molecular biological systems, statistical physics, astrophysics, condensed matter physics, nuclear physics and elementary particle physics. As one application of these results, we propose a new statistical method derived from our formalism to study random number generators used in Monte Carlo simulations. (author)

Analysis of the Nonlinear Density Wave Two-Phase Instability in a Steam Generator of 600MWe Liquid Metal Reactor

International Nuclear Information System (INIS)

Choi, Seok Ki; Kim, Seong O

2011-01-01

A 600 MWe demonstration reactor being developed at KAERI employs a once-through helically coiled steam generator. The helically coiled steam generator is compact and is efficient for heat transfer, however, it may suffer from the two-phase instability. It is well known that the density wave instability is the main source of instability among various types of instabilities in a helically coiled S/G in a LMR. In the present study a simple method for analysis of the density wave two phase instability in a liquid metal reactor S/G is proposed and the method is applied to the analysis of density wave instability in a S/G of 600MWe liquid metal reactor

An Idea for Generating Diversity Conversations: Physics Jeopardy and the Future Faces of Physics Kit

Science.gov (United States)

Rand, Kendra; White, Gary

2008-10-01

Is there a way to engage typical physics undergraduates in a conversation about under-represented groups in physics that doesn't result in rolled-eyes or fingers-in-the-ears? The Society of Physics Students (SPS) has begun an experiment using a jeopardy-like game at physics meetings in an attempt to generate conversations about diversity. The physics jeopardy game is part of a "Future Faces of Physics" kit that includes a variety of materials that are of interest to those wanting to address under-represented audiences in physics, such as video clips exhibiting common physics words in sign language, tactile representations of the lunar surface for blind students, guidelines regarding lab procedures for the wheel-chair bound, and the book, Einstein on Race and Racism with a challenge letter directed at SPS chapters from the authors. While attempts to assess the impact of the game are modest, we report anecdotally some of the qualitative features seen in the discussions when the game is played. We also strive to indulge in a few physics jeopardy game moments to give a sense of how the game works. If you are hosting a meeting, large or small, and would like to receive this kit for use at your meeting, notify Kendra Rand, SPS Program Coordinator at krand@aip.org.

Development of large high current density superconducting solenoid magnets for use in high energy physics experiments

International Nuclear Information System (INIS)

Green, M.A.

1977-05-01

The development of a unique type of large superconducting solenoid magnet, characterized by very high current density windings and a two-phase helium tubular cooling system is described. The development of the magnet's conceptual design and the construction of two test solenoids are described. The successful test of the superconducting coil and its tubular cooling refrigeration system is presented. The safety, environmental and economic impacts of the test program on future developments in high energy physics are shown. Large solid angle particle detectors for colliding beam physics will analyze both charged and neutral particles. In many cases, these detectors will require neutral particles, such as gamma rays, to pass through the magnet coil with minimum interaction. The magnet coils must be as thin as possible. The use of superconducting windings allows one to minimize radiation thickness, while at the same time maximizing charged particle momentum resolution and saving substantial quantities of electrical energy. The results of the experimental measurements show that large high current density solenoid magnets can be made to operate at high stored energies. The superconducting magnet development described has a positive safety and environmental impact. The use of large high current density thin superconducting solenoids has been proposed in two high energy physics experiments to be conducted at the Stanford Linear Accelerator Center and Cornell University as a result of the successful experiments described

MADNESS applied to density functional theory in chemistry and nuclear physics

International Nuclear Information System (INIS)

Fann, G I; Harrison, R J; Beylkin, G; Jia, J; Hartman-Baker, R; Shelton, W A; Sugiki, S

2007-01-01

We describe some recent mathematical results in constructing computational methods that lead to the development of fast and accurate multiresolution numerical methods for solving quantum chemistry and nuclear physics problems based on Density Functional Theory (DFT). Using low separation rank representations of functions and operators in conjunction with representations in multiwavelet bases, we developed a multiscale solution method for integral and differential equations and integral transforms. The Poisson equation, the Schrodinger equation, and the projector on the divergence free functions provide important examples with a wide range of applications in computational chemistry, nuclear physics, computational electromagnetic and fluid dynamics. We have implemented this approach along with adaptive representations of operators and functions in the multiwavelet basis and low separation rank (LSR) approximation of operators and functions. These methods have been realized and implemented in a software package called Multiresolution Adaptive Numerical Evaluation for Scientific Simulation (MADNESS)

The diverse density profiles of galaxy clusters with self-interacting dark matter plus baryons

Science.gov (United States)

Robertson, Andrew; Massey, Richard; Eke, Vincent; Tulin, Sean; Yu, Hai-Bo; Bahé, Yannick; Barnes, David J.; Bower, Richard G.; Crain, Robert A.; Dalla Vecchia, Claudio; Kay, Scott T.; Schaller, Matthieu; Schaye, Joop

2018-05-01

We present the first simulated galaxy clusters (M200 > 1014 M⊙) with both self-interacting dark matter (SIDM) and baryonic physics. They exhibit a greater diversity in both dark matter and stellar density profiles than their counterparts in simulations with collisionless dark matter (CDM), which is generated by the complex interplay between dark matter self-interactions and baryonic physics. Despite variations in formation history, we demonstrate that analytical Jeans modelling predicts the SIDM density profiles remarkably well, and the diverse properties of the haloes can be understood in terms of their different final baryon distributions.

Overview of physics research on the TCV tokamak

Czech Academy of Sciences Publication Activity Database

Fasoli, A.; Alberti, S.; Amorim, P.; Angioni, C.; Asp, E.; Behn, R.; Bencze, A.; Berrino, J.; Blanchard, P.; Bortolon, A.; Brunner, S.; Camenen, Y.; Cirant, S.; Coda, S.; Curchod, L.; DeMeijere, K.; Duval, B. P.; Fable, E.; Fasel, D.; Felici, F.; Furno, I.; Garcia, O.E.; Giruzzi, G.; Gnesin, S.; Goodman, T.; Graves, J.; Gudozhnik, A.; Gulejova, B.; Henderson, M.; Hogge, J. Ph.; Horáček, Jan; Joye, B.; Karpushov, A.; Kim, S.-H.; Laqua, H.; Lister, J. B.; Llobet, X.; Madeira, T.; Marinoni, A.; Marki, J.; Martin, Y.; Maslov, M.; Medvedev, S.; Moret, J.-M.; Paley, J.; Pavlov, I.; Piffl, Vojtěch; Piras, F.; Pitts, R.A.; Pitzschke, A.; Pochelon, A.; Porte, L.; Reimerdes, H.; Rossel, J.; Sauter, O.; Scarabosio, A.; Schlatter, C.; Sushkov, A.; Testa, D.; Tonetti, G.; Tskhakaya, D.; Tran, M. Q.; Turco, F.; Turri, G.; Tye, R.; Udintsev, V.; Véres, G.; Villard, L.; Weisen, H.; Zhuchkova, A.; Zucca, C.

2009-01-01

Roč. 49, č. 10 (2009), s. 104005-104005 ISSN 0029-5515 Institutional research plan: CEZ:AV0Z20430508 Keywords : overview highlights * fusion research * tokamak TCV * self-generated current * H-mode physics * Electron internal transport barrier * electron cyclotron heating * electron cyclotron current drive physics * density peaking * MHDactivity * edge physics * reciprocating Mach probe * Pfirsch–Schlueter component. Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 4.270, year: 2009 http://stacks.iop.org/NF/49/104005

Minimal-post-processing 320-Gbps true random bit generation using physical white chaos.

Science.gov (United States)

Wang, Anbang; Wang, Longsheng; Li, Pu; Wang, Yuncai

2017-02-20

Chaotic external-cavity semiconductor laser (ECL) is a promising entropy source for generation of high-speed physical random bits or digital keys. The rate and randomness is unfortunately limited by laser relaxation oscillation and external-cavity resonance, and is usually improved by complicated post processing. Here, we propose using a physical broadband white chaos generated by optical heterodyning of two ECLs as entropy source to construct high-speed random bit generation (RBG) with minimal post processing. The optical heterodyne chaos not only has a white spectrum without signature of relaxation oscillation and external-cavity resonance but also has a symmetric amplitude distribution. Thus, after quantization with a multi-bit analog-digital-convertor (ADC), random bits can be obtained by extracting several least significant bits (LSBs) without any other processing. In experiments, a white chaos with a 3-dB bandwidth of 16.7 GHz is generated. Its entropy rate is estimated as 16 Gbps by single-bit quantization which means a spectrum efficiency of 96%. With quantization using an 8-bit ADC, 320-Gbps physical RBG is achieved by directly extracting 4 LSBs at 80-GHz sampling rate.

Solitons in one-dimensional charge density wave systems

International Nuclear Information System (INIS)

Su, W.P.

1981-01-01

Theoretical research on one dimensional charge density wave systems is outlined. A simple coupled electron-photon Hamiltonian is studied including a Green's function approach, molecular dynamics, and Monte Carlo path integral method. As in superconductivity, the nonperturbative nature of the system makes the physical ground states and low energy excitations drastically different from the bare electrons and phonons. Solitons carry quantum numbers which are entirely different from those of the bare electrons and holes. The fractional charge character of the solitons is an example of this fact. Solitons are conveniently generated by doping material with donors or acceptors or by photon absorption. Most predictions of the theory are in qualitative agreement with experiments. The one dimensional charge density wave system has potential technological importance and a possible role in uncovering phenomena which might have implications in relativistic field theory and elementary particle physics

Physical degradation assessment of generator station cables

International Nuclear Information System (INIS)

Stonkus, D.J.

1988-01-01

Preliminary studies of fossil-fired and nuclear generator station cables indicate that the low voltage PVC insulated cables are in relatively good condition. The insulation is flexible and in the case of nuclear cables can withstand a design basis event after nearly 15 years of service. Cables insulated with styrene butadiene rubber have been found embrittled and cables insulated with SBR should be closely inspected in any plant assurance program. Thermal analysis using oxidative induction technique shows promise to indicate cable insulation degradation. Long term reliability assurance and plant life extension studies are being actively pursued at Ontario Hydro. A major study is currently underway to extend the life of the oldest operating fossil-fuel station, the 8-unit, 2400 MW Lakeview TGS in operation since the 1960s. Plant life assurance programs have been initiated at the 2000 MW Lambton TGS in operation since 1969, and for the oldest operating nuclear plant, Pickering NGS A in operation since the early 1970s. As cables are considered one of the critical components in a generator station due to the extreme difficulty and cost of cable replacement, test programs have been initiated to evaluate the physical degradation of the cables and relate the results to electrical diagnostic tests and to chemical changes. The decommissioning of two small nuclear stations, the 20 MW Nuclear Power Demonstration (NPD) and the 200 MW Douglas Point NGS, which were placed in service in 1962 and 1967 respectively, will provide an opportunity to perform destructive electrical and physical evaluation on field aged cables

Bone mineral density in children and adolescents: relation to puberty, calcium intake, and physical activity

NARCIS (Netherlands)

A.M. Boot (Annemieke); H.A.P. Pols (Huib); E.P. Krenning (Eric); S.M.P.F. de Muinck Keizer-Schrama (Sabine); M.A.J. de Ridder (Maria)

1997-01-01

textabstractThe association of height, weight, pubertal stage, calcium intake, and physical activity with bone mineral density (BMD) was evaluated in 500 children and adolescents (205 boys and 295 girls), aged 4-20 yr. The BMD (grams per cm2) of lumbar spine and total

Experimental nuclear level densities and γ-ray strength functions in Sc and V isotopes

International Nuclear Information System (INIS)

Larsen, A. C.; Guttormsen, M.; Ingebretsen, F.; Messelt, S.; Rekstad, J.; Siem, S.; Syed, N. U. H.; Chankova, R.; Loennroth, T.; Schiller, A.; Voinov, A.

2008-01-01

The nuclear physics group at the Oslo Cyclotron Laboratory has developed a method to extract nuclear level density and γ-ray strength function from first-generation γ-ray spectra. This method is applied on the nuclei 44,45 Sc and 50,51 V in this work. The experimental level densities of 44,45 Sc are compared to calculated level densities using a microscopic model based on BCS quasiparticles within the Nilsson level scheme. The γ-ray strength functions are also compared to theoretical expectations, showing an unexpected enhancement of the γ-ray strength for low γ energies (E γ ≤3 MeV) in all the isotopes studied here. The physical origin of this enhancement is not yet understood

Linking Soil Physical Parameters Along a Density Gradient in a Loess-Soil Long-Term Experiment

DEFF Research Database (Denmark)

Eden, Marie; Møldrup, Per; Schjønning, Per

2012-01-01

It is important to understand the impact of texture and organic carbon (OC) on soil structure development. Only few studies investigated this for silt-dominated soils. In this study, soil physical properties were determined on samples from a controlled experiment (Static Fertilization Experiment...... hydraulic conductivity. The management resulted in a distinct gradient in OC. A bulk density gradient developed from differences in amount of clay not complexed with OC. This gradient in bulk density mainly affected content of pores larger than 3 [mu]m. The air-connected porosity measured by a pycnometer...

Conceptual designs of two petawatt-class pulsed-power accelerators for high-energy-density-physics experiments

Directory of Open Access Journals (Sweden)

W. A. Stygar

2015-11-01

(MHD simulations suggest Z 300 will deliver 4.3 MJ to the liner, and achieve a yield on the order of 18 MJ. Z 800 is 52 m in diameter and stores 130 MJ. This accelerator generates 890 TW at the output of its LTD system, and delivers 65 MA in 113 ns to a MagLIF target. The peak electrical power at the MagLIF liner is 2500 TW. The principal goal of Z 800 is to achieve high-yield thermonuclear fusion; i.e., a yield that exceeds the energy initially stored by the accelerator’s capacitors. 2D MHD simulations suggest Z 800 will deliver 8.0 MJ to the liner, and achieve a yield on the order of 440 MJ. Z 300 and Z 800, or variations of these accelerators, will allow the international high-energy-density-physics community to conduct advanced inertial-confinement-fusion, radiation-physics, material-physics, and laboratory-astrophysics experiments over heretofore-inaccessible parameter regimes.

Lectures on the physics of the super dense region

International Nuclear Information System (INIS)

Key, M.H.

1980-06-01

In these notes the main physical processes of interest in laser produced plasmas in the superdense region of the plasma (densities above the critical density for penetration of the laser radiation) are discussed. The processes of energy transport and hydrodynamic compression are considered with particular emphasis on the generation of high pressure and its utilisation in the production of high density plasmas. The notes are presented under the headings; introduction, thermal conduction, plasma pressure generated by laser irradiation of a solid, shock waves, compression of matter, plasma compression and heating in exploding pusher targets, plasma compression in ablatively imploded targets. 124 references. (U.K.)

Change in physical properties of high density isotropic graphites irradiated in the ?JOYO? fast reactor

Science.gov (United States)

Maruyama, T.; Kaito, T.; Onose, S.; Shibahara, I.

1995-08-01

Thirteen kinds of isotropic graphites with different density and maximum grain size were irradiated in the experimental fast reactor "JOYO" to fluences from 2.11 to 2.86 × 10 26 n/m 2 ( E > 0.1 MeV) at temperatures from 549 to 597°C. Postirradiation examination was carried out on the dimensional changes, elastic modulus, and thermal conductivity of these materials. Dimensional change results indicate that the graphites irradiated at lower fluences showed shrinkage upon neutron irradiation followed by increase with increasing neutron fluences, irrespective of differences in material parameters. The Young's modulus and Poisson's ratio increased by two to three times the unirradiated values. The large scatter found in Poisson's ratio of unirradiated materials became very small and a linear dependence on density was obtained after irradiation. The thermal conductivity decreased to one-fifth to one-tenth of unirradiated values, with a negligible change in specific heat. The results of postirradiation examination indicated that the changes in physical properties of high density, isotropic graphites were mainly dominated by the irradiation condition rather than their material parameters. Namely, the effects of irradiation induced defects on physical properties of heavily neutron-irradiated graphites are much larger than that of defects associated with as-fabricated specimens.

Change in physical properties of high density isotropic graphites irradiated in the ''JOYO'' fast reactor

International Nuclear Information System (INIS)

Maruyama, T.; Kaito, T.; Onose, S.; Shibahara, I.

1995-01-01

Thirteen kinds of isotropic graphites with different density and maximum grain size were irradiated in the experimental fast reactor ''JOYO'' to fluences from 2.11 to 2.86x10 26 n/m 2 (E>0.1 MeV) at temperatures from 549 to 597 C. Postirradiation examination was carried out on the dimensional changes, elastic modulus, and thermal conductivity of these materials. Dimensional change results indicate that the graphites irradiated at lower fluences showed shrinkage upon neutron irradiation followed by increase with increasing neutron fluences, irrespective of differences in material parameters. The Young's modulus and Poisson's ratio increased by two to three times the unirradiated values. The large scatter found in Poisson's ratio of unirradiated materials became very small and a linear dependence on density was obtained after irradiation. The thermal conductivity decreased to one-fifth to one-tenth of unirradiated values, with a negligible change in specific heat. The results of postirradiation examination indicated that the changes in physical properties of high density, isotropic graphites were mainly dominated by the irradiation condition rather than their material parameters. Namely, the effects of irradiation induced defects on physical properties of heavily neutron-irradiated graphites are much larger than that of defects associated with as-fabricated specimens. (orig.)

Theory of sum-frequency generation spectroscopy of adsorbed molecules using the density matrix method-broadband vibrational sum-frequency generation and applications

International Nuclear Information System (INIS)

Bonn, M; Ueba, H; Wolf, M

2005-01-01

A generalized theory of frequency- and time-resolved vibrational sum-frequency generation (SFG) spectroscopy of adsorbates at surfaces is presented using the density matrix formalism. Our theoretical treatment is specifically aimed at addressing issues that accompany the relatively novel SFG approach using broadband infrared pulses. The ultrashort duration of these pulses makes them ideally suited for time-resolved investigations, for which we present a complete theoretical treatment. A second key characteristic of these pulses is their large bandwidth and high intensity, which allow for highly non-linear effects, including vibrational ladder climbing of surface vibrations. We derive general expressions relating the density matrix to SFG spectra, and apply these expressions to specific experimental results by solving the coupled optical Bloch equations of the density matrix elements. Thus, we can theoretically reproduce recent experimentally demonstrated hot band SFG spectra using femtosecond broadband infrared excitation of carbon monoxide (CO) on a Ru(001) surface

Prevalence of Low High-density Lipoprotein Cholesterol Among Adults, by Physical Activity: United States, 2011-2014.

Science.gov (United States)

Zwald, Marissa L; Akinbami, Lara J; Fakhouri, Tala H I; Fryar, Chryl D

2017-03-01

Data from the National Health and Nutrition Examination Survey •The prevalence of low high-density lipoprotein (HDL) cholesterol was significantly higher among adults who did not meet recommended physical activity guidelines (21.0%) than adults who met the guidelines (17.7%). •Low HDL cholesterol prevalence differed significantly for both men and women by adherence to physical activity guidelines. •Prevalence of low HDL cholesterol declined as age increased for both those who did and did not meet the physical activity guidelines. •Non-Hispanic white and non-Hispanic black adults who did not meet the physical activity guidelines had a higher prevalence than those who met the guidelines. •Low HDL cholesterol prevalence declined with increasing education level regardless of adherence to physical activity guidelines. Regular physical activity can improve cholesterol levels among adults, including increasing high-density lipoprotein (HDL) cholesterol (1). HDL cholesterol is known as "good" cholesterol because high levels can reduce cardiovascular disease risk (2). The 2008 Physical Activity Guidelines for Americans recommend that adults engage in 150 minutes or more of moderate-intensity aerobic activity per week, 75 minutes of vigorous-intensity aerobic activity per week, or an equivalent combination (3). Adherence to these guidelines is expected to decrease the prevalence of low HDL cholesterol levels (4-8). This report presents national data for 2011-2014 on low HDL cholesterol prevalence among U.S. adults aged 20 and over, by whether they met these guidelines. All material appearing in this report is in the public domain and may be reproduced or copied without permission; citation as to source, however, is appreciated.

Large high current density superconducting solenoids for use in high energy physics experiments

International Nuclear Information System (INIS)

Green, M.A.; Eberhard, P.H.; Taylor, J.D.

1976-05-01

Very often the study of high energy physics in colliding beam storage-rings requires a large magnetic field volume in order to detect and analyze charged particles which are created from the collision of two particle beams. Large superconducting solenoids which are greater than 1 meter in diameter are required for this kind of physics. In many cases, interesting physics can be done outside the magnet coil, and this often requires that the amount of material in the magnet coil be minimized. As a result, these solenoids should have high current density (up to 10 9 A m -2 ) superconducting windings. The methods commonly used to stabilize large superconducting magnets cannot be employed because of this need to minimize the amount of material in the coils. A description is given of the Lawrence Berkeley Laboratory program for building and testing prototype solenoid magnets which are designed to operate at coil current densities in excess of 10 9 A m -2 with magnetic stored energies which are as high as 1.5 Megajoules per meter of solenoid length. The coils use intrinsically stable multifilament Nb--Ti superconductors. Control of the magnetic field quench is achieved by using a low resistance aluminum bore tube which is inductively coupled to the coil. The inner cryostat is replaced by a tubular cooling system which carries two phase liquid helium. The magnet coil, the cooling tubes, and aluminum bore tube are cast in epoxy to form a single unified magnet and cryogenic system which is about 2 centimeters thick. The results of the magnet coil tests are discussed

Generative Representations for the Automated Design of Modular Physical Robots

Science.gov (United States)

Hornby, Gregory S.; Lipson, Hod; Pollack, Jordan B.

2003-01-01

We will begin with a brief background of evolutionary robotics and related work, and demonstrate the scaling problem with our own prior results. Next we propose the use of an evolved generative representation as opposed to a non-generative representation. We describe this representation in detail as well as the evolutionary process that uses it. We then compare progress of evolved robots with and without the use of the grammar, and quantify the obtained advantage. Working two- dimensional and three-dimensional physical robots produced by the system are shown.

Atlas Pulsed Power Facility for High Energy Density Physics Experiments

International Nuclear Information System (INIS)

Miller, R.B.; Ballard, E.O.; Barr, G.W.; Bowman, D.W.; Chochrane, J.C.; Davis, H.A.; Elizondo, J.M.; Gribble, R.F.; Griego, J.R.; Hicks, R.D.; Hinckley, W.B.; Hosack, K.W.; Nielsen, K.E.; Parker, J.V.; Parsons, M.O.; Rickets, R.L.; Salazar, H.R.; Sanchez, P.G.; Scudder, D.W.; Shapiro, C.; Thompson, M.C.; Trainor, R.J.; Valdez, G.A.; Vigil, B.N.; Watt, R.G.; Wysock, F.J.

1999-01-01

The Atlas facility, now under construction at Los Alamos National Laboratory (LANL), will provide a unique capability for performing high-energy-density experiments in support of weapon-physics and basic-research programs. It is intended to be an international user facility, providing opportunities for researchers from national laboratories and academic institutions around the world. Emphasizing institutions around the world. Emphasizing hydrodynamic experiments, Atlas will provide the capability for achieving steady shock pressures exceeding 10-Mbar in a volume of several cubic centimeters. In addition, the kinetic energy associated with solid liner implosion velocities exceeding 12 km/s is sufficient to drive dense, hydrodynamic targets into the ionized regime, permitting the study of complex issues associated with strongly-coupled plasmas. The primary element of Atlas is a 23-MJ capacitor bank, comprised of 96 separate Marx generators housed in 12 separate oil-filled tanks, surrounding a central target chamber. Each tank will house two, independently-removable maintenance units, with each maintenance unit consisting of four Marx modules. Each Marx module has four capacitors that can each be charged to a maximum of 60 kilovolts. When railgap switches are triggered, the marx modules erect to a maximum of 240 kV. The parallel discharge of these 96 Marx modules will deliver a 30-MA current pulse with a 4-5-micros risetime to a cylindrical, imploding liner via 24 vertical, tri-plate, oil-insulated transmission lines. An experimental program for testing and certifying all Marx and transmission line components has been completed. A complete maintenance module and its associated transmission line (the First Article) are now under construction and testing. The current Atlas schedule calls for construction of the machine to be complete by August, 2000. Acceptance testing is scheduled to begin in November, 2000, leading to initial operations in January, 2001

Thermodynamic, energy efficiency, and power density analysis of reverse electrodialysis power generation with natural salinity gradients.

Science.gov (United States)

Yip, Ngai Yin; Vermaas, David A; Nijmeijer, Kitty; Elimelech, Menachem

2014-05-06

Reverse electrodialysis (RED) can harness the Gibbs free energy of mixing when fresh river water flows into the sea for sustainable power generation. In this study, we carry out a thermodynamic and energy efficiency analysis of RED power generation, and assess the membrane power density. First, we present a reversible thermodynamic model for RED and verify that the theoretical maximum extractable work in a reversible RED process is identical to the Gibbs free energy of mixing. Work extraction in an irreversible process with maximized power density using a constant-resistance load is then examined to assess the energy conversion efficiency and power density. With equal volumes of seawater and river water, energy conversion efficiency of ∼ 33-44% can be obtained in RED, while the rest is lost through dissipation in the internal resistance of the ion-exchange membrane stack. We show that imperfections in the selectivity of typical ion exchange membranes (namely, co-ion transport, osmosis, and electro-osmosis) can detrimentally lower efficiency by up to 26%, with co-ion leakage being the dominant effect. Further inspection of the power density profile during RED revealed inherent ineffectiveness toward the end of the process. By judicious early discontinuation of the controlled mixing process, the overall power density performance can be considerably enhanced by up to 7-fold, without significant compromise to the energy efficiency. Additionally, membrane resistance was found to be an important factor in determining the power densities attainable. Lastly, the performance of an RED stack was examined for different membrane conductivities and intermembrane distances simulating high performance membranes and stack design. By thoughtful selection of the operating parameters, an efficiency of ∼ 37% and an overall gross power density of 3.5 W/m(2) represent the maximum performance that can potentially be achieved in a seawater-river water RED system with low

Magmatic densities control erupted volumes in Icelandic volcanic systems

Science.gov (United States)

Hartley, Margaret; Maclennan, John

2018-04-01

Magmatic density and viscosity exert fundamental controls on the eruptibility of magmas. In this study, we investigate the extent to which magmatic physical properties control the eruptibility of magmas from Iceland's Northern Volcanic Zone (NVZ). By studying subaerial flows of known age and volume, we are able to directly relate erupted volumes to magmatic physical properties, a task that has been near-impossible when dealing with submarine samples dredged from mid-ocean ridges. We find a strong correlation between magmatic density and observed erupted volumes on the NVZ. Over 85% of the total volume of erupted material lies close to a density and viscosity minimum that corresponds to the composition of basalts at the arrival of plagioclase on the liquidus. These magmas are buoyant with respect to the Icelandic upper crust. However, a number of small-volume eruptions with densities greater than typical Icelandic upper crust are also found in Iceland's neovolcanic zones. We use a simple numerical model to demonstrate that the eruption of magmas with higher densities and viscosities is facilitated by the generation of overpressure in magma chambers in the lower crust and uppermost mantle. This conclusion is in agreement with petrological constraints on the depths of crystallisation under Iceland.

Magmatic Densities Control Erupted Volumes in Icelandic Volcanic Systems

Directory of Open Access Journals (Sweden)

Margaret Hartley

2018-04-01

Full Text Available Magmatic density and viscosity exert fundamental controls on the eruptibility of magmas. In this study, we investigate the extent to which magmatic physical properties control the eruptibility of magmas from Iceland's Northern Volcanic Zone (NVZ. By studying subaerial flows of known age and volume, we are able to directly relate erupted volumes to magmatic physical properties, a task that has been near-impossible when dealing with submarine samples dredged from mid-ocean ridges. We find a strong correlation between magmatic density and observed erupted volumes on the NVZ. Over 85% of the total volume of erupted material lies close to a density and viscosity minimum that corresponds to the composition of basalts at the arrival of plagioclase on the liquidus. These magmas are buoyant with respect to the Icelandic upper crust. However, a number of small-volume eruptions with densities greater than typical Icelandic upper crust are also found in Iceland's neovolcanic zones. We use a simple numerical model to demonstrate that the eruption of magmas with higher densities and viscosities is facilitated by the generation of overpressure in magma chambers in the lower crust and uppermost mantle. This conclusion is in agreement with petrological constraints on the depths of crystallization under Iceland.

Thermospheric density and satellite drag modeling

Science.gov (United States)

Mehta, Piyush Mukesh

The United States depends heavily on its space infrastructure for a vast number of commercial and military applications. Space Situational Awareness (SSA) and Threat Assessment require maintaining accurate knowledge of the orbits of resident space objects (RSOs) and the associated uncertainties. Atmospheric drag is the largest source of uncertainty for low-perigee RSOs. The uncertainty stems from inaccurate modeling of neutral atmospheric mass density and inaccurate modeling of the interaction between the atmosphere and the RSO. In order to reduce the uncertainty in drag modeling, both atmospheric density and drag coefficient (CD) models need to be improved. Early atmospheric density models were developed from orbital drag data or observations of a few early compact satellites. To simplify calculations, densities derived from orbit data used a fixed CD value of 2.2 measured in a laboratory using clean surfaces. Measurements from pressure gauges obtained in the early 1990s have confirmed the adsorption of atomic oxygen on satellite surfaces. The varying levels of adsorbed oxygen along with the constantly changing atmospheric conditions cause large variations in CD with altitude and along the orbit of the satellite. Therefore, the use of a fixed CD in early development has resulted in large biases in atmospheric density models. A technique for generating corrections to empirical density models using precision orbit ephemerides (POE) as measurements in an optimal orbit determination process was recently developed. The process generates simultaneous corrections to the atmospheric density and ballistic coefficient (BC) by modeling the corrections as statistical exponentially decaying Gauss-Markov processes. The technique has been successfully implemented in generating density corrections using the CHAMP and GRACE satellites. This work examines the effectiveness, specifically the transfer of density models errors into BC estimates, of the technique using the CHAMP and

Postfragmentation density function for bacterial aggregates in laminar flow.

Science.gov (United States)

Byrne, Erin; Dzul, Steve; Solomon, Michael; Younger, John; Bortz, David M

2011-04-01

The postfragmentation probability density of daughter flocs is one of the least well-understood aspects of modeling flocculation. We use three-dimensional positional data of Klebsiella pneumoniae bacterial flocs in suspension and the knowledge of hydrodynamic properties of a laminar flow field to construct a probability density function of floc volumes after a fragmentation event. We provide computational results which predict that the primary fragmentation mechanism for large flocs is erosion. The postfragmentation probability density function has a strong dependence on the size of the original floc and indicates that most fragmentation events result in clumps of one to three bacteria eroding from the original floc. We also provide numerical evidence that exhaustive fragmentation yields a limiting density inconsistent with the log-normal density predicted in the literature, most likely due to the heterogeneous nature of K. pneumoniae flocs. To support our conclusions, artificial flocs were generated and display similar postfragmentation density and exhaustive fragmentation. ©2011 American Physical Society

Multiple exciton generation in chiral carbon nanotubes: Density functional theory based computation

Science.gov (United States)

Kryjevski, Andrei; Mihaylov, Deyan; Kilina, Svetlana; Kilin, Dmitri

2017-10-01

We use a Boltzmann transport equation (BE) to study time evolution of a photo-excited state in a nanoparticle including phonon-mediated exciton relaxation and the multiple exciton generation (MEG) processes, such as exciton-to-biexciton multiplication and biexciton-to-exciton recombination. BE collision integrals are computed using Kadanoff-Baym-Keldysh many-body perturbation theory based on density functional theory simulations, including exciton effects. We compute internal quantum efficiency (QE), which is the number of excitons generated from an absorbed photon in the course of the relaxation. We apply this approach to chiral single-wall carbon nanotubes (SWCNTs), such as (6,2) and (6,5). We predict efficient MEG in the (6,2) and (6,5) SWCNTs within the solar spectrum range starting at the 2Eg energy threshold and with QE reaching ˜1.6 at about 3Eg, where Eg is the electronic gap.

Gap formation processes in a high-density plasma opening switch

International Nuclear Information System (INIS)

Grossmann, J.M.; Swanekamp, S.B.; Ottinger, P.F.; Commisso, R.J.; Hinshelwood, D.D.; Weber, B.V.

1995-01-01

A gap opening process in plasma opening switches (POS) is examined with the aid of numerical simulations. In these simulations, a high density (n e =10 14 --5x10 15 cm -3 ) uniform plasma initially bridges a small section of the coaxial transmission line of an inductive energy storage generator. A short section of vacuum transmission line connects the POS to a short circuit load. The results presented here extend previous simulations in the n e =10 12 --10 13 cm -3 density regime. The simulations show that a two-dimensional (2-D) sheath forms in the plasma near a cathode. This sheath is positively charged, and electrostatic sheath potentials that are large compared to the anode--cathode voltage develop. Initially, the 2-D sheath is located at the generator edge of the plasma. As ions are accelerated out of the sheath, it retains its original 2-D structure, but migrates axially toward the load creating a magnetically insulated gap in its wake. When the sheath reaches the load edge of the POS, the POS stops conducting current and the load current increases rapidly. At the end of the conduction phase a gap exists in the POS whose size is determined by the radial dimensions of the 2-D sheath. Simulations at various plasma densities and current levels show that the radial size of the gap scales roughly as B/n e , where B is the magnetic field. The results of this work are discussed in the context of long-conduction-time POS physics, but exhibit the same physical gap formation mechanisms as earlier lower density simulations more relevant to short-conduction-time POS. copyright 1995 American Institute of Physics

THE PHYSICAL ORIGINS OF THE MORPHOLOGY-DENSITY RELATION: EVIDENCE FOR GAS STRIPPING FROM THE SLOAN DIGITAL SKY SURVEY

International Nuclear Information System (INIS)

Van der Wel, Arjen; Bell, Eric F.; Skibba, Ramin A.; Rix, Hans-Walter; Holden, Bradford P.

2010-01-01

We provide a physical interpretation and explanation of the morphology-density relation for galaxies, drawing on stellar masses, star formation rates, axis ratios, and group halo masses from the Sloan Digital Sky Survey. We first re-cast the classical morphology-density relation in more quantitative terms, using low star formation rate (quiescence) as a proxy for early-type morphology and dark matter halo mass from a group catalog as a proxy for environmental density: for galaxies of a given stellar mass the quiescent fraction is found to increase with increasing dark matter halo mass. Our novel result is that-at a given stellar mass-quiescent galaxies are significantly flatter in dense environments, implying a higher fraction of disk galaxies. Supposing that the denser environments differ simply by a higher incidence of quiescent disk galaxies that are structurally similar to star-forming disk galaxies of similar mass, explains simultaneously and quantitatively these quiescence-environment and shape-environment relations. Our findings add considerable weight to the slow removal of gas as the main physical driver of the morphology-density relation, at the expense of other explanations.

Research on high energy density plasmas and applications

International Nuclear Information System (INIS)

1999-01-01

Recently, technologies on lasers, accelerators, and pulse power machines have been significantly advanced and input power density covers the intensity range from 10 10 W/cm 2 to higher than 10 20 W/cm 2 . As the results, high pressure gas and solid targets can be heated up to very high temperature to create hot dense plasmas which have never appeared on the earth. The high energy density plasmas opened up new research fields such as inertial confinement fusion, high brightness X-ray radiation sources, interiors of galactic nucleus,supernova, stars and planets, ultra high pressure condensed matter physics, plasma particle accelerator, X-ray laser, and so on. Furthermore, since these fields are intimately connected with various industrial sciences and technologies, the high energy density plasma is now studied in industries, government institutions, and so on. This special issue of the Journal of Plasma Physics and Nuclear Fusion Research reviews the high energy density plasma science for the comprehensive understanding of such new fields. In May, 1998, the review committee for investigating the present status and the future prospects of high energy density plasma science was established in the Japan Society of Plasma Science and Nuclear Fusion Research. We held three committee meetings to discuss present status and critical issues of research items related to high energy density plasmas. This special issue summarizes the understandings of the committee. This special issue consists of four chapters: They are Chapter 1: Physics important in the high energy density plasmas, Chapter 2: Technologies related to the plasma generation; drivers such as lasers, pulse power machines, particle beams and fabrication of various targets, Chapter 3: Plasma diagnostics important in high energy density plasma experiments, Chapter 4: A variety of applications of high energy density plasmas; X-ray radiation, particle acceleration, inertial confinement fusion, laboratory astrophysics

Constraining snowmelt in a temperature-index model using simulated snow densities

KAUST Repository

Bormann, Kathryn J.

2014-09-01

Current snowmelt parameterisation schemes are largely untested in warmer maritime snowfields, where physical snow properties can differ substantially from the more common colder snow environments. Physical properties such as snow density influence the thermal properties of snow layers and are likely to be important for snowmelt rates. Existing methods for incorporating physical snow properties into temperature-index models (TIMs) require frequent snow density observations. These observations are often unavailable in less monitored snow environments. In this study, previous techniques for end-of-season snow density estimation (Bormann et al., 2013) were enhanced and used as a basis for generating daily snow density data from climate inputs. When evaluated against 2970 observations, the snow density model outperforms a regionalised density-time curve reducing biases from -0.027gcm-3 to -0.004gcm-3 (7%). The simulated daily densities were used at 13 sites in the warmer maritime snowfields of Australia to parameterise snowmelt estimation. With absolute snow water equivalent (SWE) errors between 100 and 136mm, the snow model performance was generally lower in the study region than that reported for colder snow environments, which may be attributed to high annual variability. Model performance was strongly dependent on both calibration and the adjustment for precipitation undercatch errors, which influenced model calibration parameters by 150-200%. Comparison of the density-based snowmelt algorithm against a typical temperature-index model revealed only minor differences between the two snowmelt schemes for estimation of SWE. However, when the model was evaluated against snow depths, the new scheme reduced errors by up to 50%, largely due to improved SWE to depth conversions. While this study demonstrates the use of simulated snow density in snowmelt parameterisation, the snow density model may also be of broad interest for snow depth to SWE conversion. Overall, the

Constraining snowmelt in a temperature-index model using simulated snow densities

KAUST Repository

Bormann, Kathryn J.; Evans, Jason P.; McCabe, Matthew

2014-01-01

Current snowmelt parameterisation schemes are largely untested in warmer maritime snowfields, where physical snow properties can differ substantially from the more common colder snow environments. Physical properties such as snow density influence the thermal properties of snow layers and are likely to be important for snowmelt rates. Existing methods for incorporating physical snow properties into temperature-index models (TIMs) require frequent snow density observations. These observations are often unavailable in less monitored snow environments. In this study, previous techniques for end-of-season snow density estimation (Bormann et al., 2013) were enhanced and used as a basis for generating daily snow density data from climate inputs. When evaluated against 2970 observations, the snow density model outperforms a regionalised density-time curve reducing biases from -0.027gcm-3 to -0.004gcm-3 (7%). The simulated daily densities were used at 13 sites in the warmer maritime snowfields of Australia to parameterise snowmelt estimation. With absolute snow water equivalent (SWE) errors between 100 and 136mm, the snow model performance was generally lower in the study region than that reported for colder snow environments, which may be attributed to high annual variability. Model performance was strongly dependent on both calibration and the adjustment for precipitation undercatch errors, which influenced model calibration parameters by 150-200%. Comparison of the density-based snowmelt algorithm against a typical temperature-index model revealed only minor differences between the two snowmelt schemes for estimation of SWE. However, when the model was evaluated against snow depths, the new scheme reduced errors by up to 50%, largely due to improved SWE to depth conversions. While this study demonstrates the use of simulated snow density in snowmelt parameterisation, the snow density model may also be of broad interest for snow depth to SWE conversion. Overall, the

The Next Generation Science Standards: A Focus on Physical Science

Science.gov (United States)

Krajcik, Joe

2013-01-01

This article describes ways to adapt U.S. science curriculum to the U.S. National Research Council (NRC) "Framework for K-12 Science Education" and "Next Generation of Science Standards" (NGSS), noting their focus on teaching the physical sciences. The overall goal of the Framework and NGSS is to help all learners develop the…

Physical activity and 5-year changes in physical performance tests and bone mineral density in postmenopausal women: the Yokogoshi Study.

Science.gov (United States)

Kitamura, Kaori; Nakamura, Kazutoshi; Kobayashi, Ryosaku; Oshiki, Rieko; Saito, Toshiko; Oyama, Mari; Takahashi, Shunsuke; Nishiwaki, Tomoko; Iwasaki, Masanori; Yoshihara, Akihiro

2011-09-01

The effect of physical activity on musculoskeletal health in older adults is not completely understood. The aim of this study was to determine the relationship between physical activity and 5-year changes in physical performance tests and bone mineral density (BMD) in postmenopausal women. The design was a 5-year cohort study. Subjects were 507 women (55-74 years old) living in a rural community in Japan. Physical activity assessed included housework, farm work, and moderate leisure-time physical activity within the previous week. Measurements at baseline included handgrip strength, walking time (timed "Up & Go" test) and BMD of the femoral neck and vertebrae. Five-year changes in these measures (outcome variables) were compared among groups with different levels of physical activity by analysis of covariance. Women who did not do housework performed worse in changes in handgrip strength (difference=2.22 kg, P=0.0201) and worse in changes in the walking time (difference=0.54 s, P=0.0072) than those who did housework alone. Women who spent at least 9h per week (median=24) doing farm work performed better in changes in handgrip strength (difference=0.28 kg, P=0.0334), but worse in changes in the walking time (difference=0.66 s, Pwork. However, leisure-time activity was not associated with changes in any outcome variable, and none of the physical activities predicted BMD changes. Engaging in housework and farm work are determinants of physical function in postmenopausal women, which may help them maintain independence in daily living. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Les Houches guidebook to Monte Carlo generators for hadron collider physics

International Nuclear Information System (INIS)

Dobbs, Matt A.; Frixione, Stefano; Laenen, Eric; Tollefson, Kirsten

2004-01-01

Recently the collider physics community has seen significant advances in the formalisms and implementations of event generators. This review is a primer of the methods commonly used for the simulation of high energy physics events at particle colliders. We provide brief descriptions, references, and links to the specific computer codes which implement the methods. The aim is to provide an overview of the available tools, allowing the reader to ascertain which tool is best for a particular application, but also making clear the limitations of each tool

Les Houches guidebook to Monte Carlo generators for hadron collider physics

CERN Document Server

Dobbs, M.A.; Laenen, Eric; Tollefson, K.; Baer, H.; Boos, E.; Cox, B.; Engel, R.; Giele, W.; Huston, J.; Ilyin, S.; Kersevan, B.; Krauss, F.; Kurihara, Y.; Lonnblad, L.; Maltoni, F.; Mangano, M.; Odaka, S.; Richardson, P.; Ryd, A.; Sjostrand, T.; Skands, Peter Z.; Was, Z.; Webber, B.R.; Zeppenfeld, D.

2005-01-01

Recently the collider physics community has seen significant advances in the formalisms and implementations of event generators. This review is a primer of the methods commonly used for the simulation of high energy physics events at particle colliders. We provide brief descriptions, references, and links to the specific computer codes which implement the methods. The aim is to provide an overview of the available tools, allowing the reader to ascertain which tool is best for a particular application, but also making clear the limitations of each tool.

Artificial cognitive memory—changing from density driven to functionality driven

Science.gov (United States)

Shi, L. P.; Yi, K. J.; Ramanathan, K.; Zhao, R.; Ning, N.; Ding, D.; Chong, T. C.

2011-03-01

Increasing density based on bit size reduction is currently a main driving force for the development of data storage technologies. However, it is expected that all of the current available storage technologies might approach their physical limits in around 15 to 20 years due to miniaturization. To further advance the storage technologies, it is required to explore a new development trend that is different from density driven. One possible direction is to derive insights from biological counterparts. Unlike physical memories that have a single function of data storage, human memory is versatile. It contributes to functions of data storage, information processing, and most importantly, cognitive functions such as adaptation, learning, perception, knowledge generation, etc. In this paper, a brief review of current data storage technologies are presented, followed by discussions of future storage technology development trend. We expect that the driving force will evolve from density to functionality, and new memory modules associated with additional functions other than only data storage will appear. As an initial step toward building a future generation memory technology, we propose Artificial Cognitive Memory (ACM), a memory based intelligent system. We also present the characteristics of ACM, new technologies that can be used to develop ACM components such as bioinspired element cells (silicon, memristor, phase change, etc.), and possible methodologies to construct a biologically inspired hierarchical system.

Lifetime physical activity and calcium intake related to bone density in young women.

Science.gov (United States)

Wallace, Lorraine Silver; Ballard, Joyce E

2002-05-01

Osteoporosis is a significant public health problem associated with increased mortality and morbidity. Our aim in this cross-sectional study was to investigate the relationship between lifetime physical activity and calcium intake and bone mineral density (BMD) and BMC (bone mineral content) in 42 regularly menstruating Caucasian women (age 21.26+/-1.91 years, BMI 23.83+/-5.85). BMD and BMC at the lumbar spine (L2-L4), hip (femoral neck, trochanter, total), and total body were assessed by dual energy x-ray absorptiometry (DXA). Lifetime history of physical activity and calcium intake was obtained by a structured interview using valid and reliable instruments. Measures of both lifetime physical activity and calcium intake were highly correlated. In stepwise multiple regression analyses, lean mass was the most important and consistent factor for predicting BMD and BMC at all skeletal sites (attributable r2 = 28.8%-78.7%). Lifetime physical activity contributed to 3.0% of the variation in total body BMD, and life-time weight-bearing physical activity explained 15.1% of variance in lumbar spine BMC. Current calcium intake predicted 6% of the variance in BMD at the femoral neck and trochanter. We found lean mass to be a powerful predictor of BMD and BMC in young women. Because lean mass can be modified to some extent by physical activity, public health efforts must be directed at increasing physical activity throughout the lifespan. Furthermore, our results suggest that adequate calcium intake may help to enhance bone mass, thus decreasing the risk of osteoporotic fracture later in life.

Influence of the electron density on the characteristics of terahertz waves generated under laser–cluster interaction

Energy Technology Data Exchange (ETDEWEB)

Frolov, A. A., E-mail: frolov@ihed.ras.ru [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2016-12-15

A theory of generation of terahertz radiation under laser–cluster interaction, developed earlier for an overdense cluster plasma [A. A. Frolov, Plasma Phys. Rep. 42. 637 (2016)], is generalized for the case of arbitrary electron density. The spectral composition of radiation is shown to substantially depend on the density of free electrons in the cluster. For an underdense cluster plasma, there is a sharp peak in the terahertz spectrum at the frequency of the quadrupole mode of a plasma sphere. As the electron density increases to supercritical values, this spectral line vanishes and a broad maximum at the frequency comparable with the reciprocal of the laser pulse duration appears in the spectrum. The dependence of the total energy of terahertz radiation on the density of free electrons is analyzed. The radiation yield is shown to increase significantly under resonance conditions, when the laser frequency is close to the eigenfrequency of the dipole or quadrupole mode of a plasma sphere.

Entropy Generation and Human Aging: Lifespan Entropy and Effect of Physical Activity Level

Science.gov (United States)

Silva, Carlos; Annamalai, Kalyan

2008-06-01

The first and second laws of thermodynamics were applied to biochemical reactions typical of human metabolism. An open-system model was used for a human body. Energy conservation, availability and entropy balances were performed to obtain the entropy generated for the main food components. Quantitative results for entropy generation were obtained as a function of age using the databases from the U.S. Food and Nutrition Board (FNB) and Centers for Disease Control and Prevention (CDC), which provide energy requirements and food intake composition as a function of age, weight and stature. Numerical integration was performed through human lifespan for different levels of physical activity. Results were presented and analyzed. Entropy generated over the lifespan of average individuals (natural death) was found to be 11,404 kJ/ºK per kg of body mass with a rate of generation three times higher on infants than on the elderly. The entropy generated predicts a life span of 73.78 and 81.61 years for the average U.S. male and female individuals respectively, which are values that closely match the average lifespan from statistics (74.63 and 80.36 years). From the analysis of the effect of different activity levels, it is shown that entropy generated increases with physical activity, suggesting that exercise should be kept to a “healthy minimum” if entropy generation is to be minimized.

Evaluation of physical stability and leachability of Portland Pozzolona Cement (PPC) solidified chemical sludge generated from textile wastewater treatment plants

International Nuclear Information System (INIS)

Patel, Hema; Pandey, Suneel

2012-01-01

Highlights: ► Stabilization/solidification of chemical sludge from textile wastewater treatment plants using Portland Pozzolona Cement (PPC) containing fly ash. ► Physical engineering (compressive strength and block density) indicates that sludge has potential to be reused for construction purpose after stabilization/solidification. ► Leaching of heavy metals from stabilized/solidified materials were within stipulated limits. ► There is a modification of microstructural properties of PPC with sludge addition as indicated by XRD and SEM patterns. - Abstract: The chemical sludge generated from the treatment of textile dyeing wastewater is a hazardous waste as per Indian Hazardous Waste Management rules. In this paper, stabilization/solidification of chemical sludge was carried out to explore its reuse potential in the construction materials. Portland Pozzolona Cement (PPC) was selected as the binder system which is commercially available cement with 10–25% fly ash interground in it. The stabilized/solidified blocks were evaluated in terms of unconfined compressive strength, block density and leaching of heavy metals. The compressive strength (3.62–33.62 MPa) and block density (1222.17–1688.72 kg/m 3 ) values as well as the negligible leaching of heavy metals from the stabilized/solidified blocks indicate that there is a potential of its use for structural and non-structural applications.

A physically motivated sparse cubature scheme with applications to molecular density-functional theory

International Nuclear Information System (INIS)

Rodriguez, Juan I; Thompson, David C; Anderson, James S M; Thomson, Jordan W; Ayers, Paul W

2008-01-01

We present a novel approach for performing multi-dimensional integration of arbitrary functions. The method starts with Smolyak-type sparse grids as cubature formulae on the unit cube and uses a transformation of coordinates based on the conditional distribution method to adapt those formulae to real space. Our method is tested on integrals in one, two, three and six dimensions. The three dimensional integration formulae are used to evaluate atomic interaction energies via the Gordon-Kim model. The six dimensional integration formulae are tested in conjunction with the nonlocal exchange-correlation energy functional proposed by Lee and Parr. This methodology is versatile and powerful; we contemplate application to frozen-density embedding, next-generation molecular-mechanics force fields, 'kernel-type' exchange-correlation energy functionals and pair-density functional theory

The effect of water physical quality and water level changes on the occurrence and density of larvae of Anopheles mosquitoes around the shoreline of the Koka reservoir, Central Ethiopia

Science.gov (United States)

Teklu, B. M.; Tekie, H.; McCartney, M.; Kibret, S.

2010-08-01

Entomological studies to determine the effect of the physical characteristics of larval breeding water bodies and reservoir water level changes on the occurrence of Anopheles mosquito larvae and on the spatial and temporal formation of larval breeding habitats were conducted in two villages at Koka reservoir between August and December 2007. Of the two study villages, Ejersa is in close proximity to the reservoir, and Kuma is 5 km away from it. Data on the type, number and physical characteristics of Anopheles larval breeding habitat, species composition and densities of anopheles mosquitoes in and around the study villages were investigated and recorded. Meteorological and reservoir water level data were compared with availability of Anopheles larval breeding sites and densities. Entomological data from the weekly larval collections showed that Anopheles pharoensis Theobald, Anopheles gambiae s.l. Giles, Anopheles coustani Laveran and Anopheles squamosus Theobald were breeding in the study area. The mean larval density of A. gambiae s.l. in this study was higher in slightly turbid and shallow aquatic habitats than in turbid and relatively deep aquatic habitats (F=16.97, plevels and the number of positive breeding habitats at Ejersa during the sampling period (r=0.605, pphysical characteristics such as water temperature, turbidity, depth and vegetation cover play an important role in the species composition, total Anopheles larval count, and the density of Anopheles mosquitoes in the vicinity. The proliferation of suitable breeding habitats around the reservoir villages is strongly associated with reservoir water level changes. This is particularly important for A. pharoensis and A. arabiensis which are important vectors of malaria in the area. Further investigation on the species diversity, physical and chemical habitat characteristics and impact of water holding capacity of the soil need to be done to generate detailed baseline data which will serve as a basis

Frontiers of plasma physics. III. The implications of nonlinearity

International Nuclear Information System (INIS)

Bardwell, S.

1977-01-01

In the first two articles of this series, Bardwell reviewed the experimental evidence that points to an inherent nonlinear quality in plasmas. Evidence from strongly turbulent plasmas, where the energy in the plasma's collective motions is comparable to the energy in random motion, leads to the speculation that high energy-density plasmas can provide insight into previously inaccessible regimes of physical behavior. Both laboratory and astrophysical plasmas show a marked tendency to generate self-ordered, large-scale structures; islands of self-generated magnetic field, circulation cells, vortices, and filaments are among the most remarkable of these. These self-ordered phenomena, Bardwell reports, challenge in a fundamental way the conceptual tools of physics as they are presently understood. In part two of this series, Bardwell draws on the connection between linearity and entropy, a topic also examined in Levitt's companion piece in the September 1976 FEF Newsletter, to conclude that these difficulties in plasma physics stem from the invalid extension of contemporary physics, which is basically linear, to high-energy density regimes of a plasma; contemporary physics in these cases is inapplicable. Readers without a background in mathematics should not be deterred by the mathematical formalism in the last section of the article; the text can be understood without a detailed mastery of the mathematical formulae

Computational complexity of time-dependent density functional theory

International Nuclear Information System (INIS)

Whitfield, J D; Yung, M-H; Tempel, D G; Aspuru-Guzik, A; Boixo, S

2014-01-01

Time-dependent density functional theory (TDDFT) is rapidly emerging as a premier method for solving dynamical many-body problems in physics and chemistry. The mathematical foundations of TDDFT are established through the formal existence of a fictitious non-interacting system (known as the Kohn–Sham system), which can reproduce the one-electron reduced probability density of the actual system. We build upon these works and show that on the interior of the domain of existence, the Kohn–Sham system can be efficiently obtained given the time-dependent density. We introduce a V-representability parameter which diverges at the boundary of the existence domain and serves to quantify the numerical difficulty of constructing the Kohn-Sham potential. For bounded values of V-representability, we present a polynomial time quantum algorithm to generate the time-dependent Kohn–Sham potential with controllable error bounds. (paper)

Cosmology and particle physics

International Nuclear Information System (INIS)

Barrow, J.D.

1982-01-01

A brief overview is given of recent work that integrates cosmology and particle physics. The observational data regarding the abundance of matter and radiation in the Universe is described. The manner in which the cosmological survival density of stable massive particles can be calculated is discussed along with the process of cosmological nucleosynthesis. Several applications of these general arguments are given with reference to the survival density of nucleons, neutrinos and unconfined fractionally charge particles. The use of nucleosynthesis to limit the number of lepton generations is described together with the implications of a small neutrino mass for the origin of galaxies and clusters. (Auth.)

Next Generation Driver for Attosecond and Laser-plasma Physics.

Science.gov (United States)

Rivas, D E; Borot, A; Cardenas, D E; Marcus, G; Gu, X; Herrmann, D; Xu, J; Tan, J; Kormin, D; Ma, G; Dallari, W; Tsakiris, G D; Földes, I B; Chou, S-W; Weidman, M; Bergues, B; Wittmann, T; Schröder, H; Tzallas, P; Charalambidis, D; Razskazovskaya, O; Pervak, V; Krausz, F; Veisz, L

2017-07-12

The observation and manipulation of electron dynamics in matter call for attosecond light pulses, routinely available from high-order harmonic generation driven by few-femtosecond lasers. However, the energy limitation of these lasers supports only weak sources and correspondingly linear attosecond studies. Here we report on an optical parametric synthesizer designed for nonlinear attosecond optics and relativistic laser-plasma physics. This synthesizer uniquely combines ultra-relativistic focused intensities of about 10 20  W/cm 2 with a pulse duration of sub-two carrier-wave cycles. The coherent combination of two sequentially amplified and complementary spectral ranges yields sub-5-fs pulses with multi-TW peak power. The application of this source allows the generation of a broad spectral continuum at 100-eV photon energy in gases as well as high-order harmonics in relativistic plasmas. Unprecedented spatio-temporal confinement of light now permits the investigation of electric-field-driven electron phenomena in the relativistic regime and ultimately the rise of next-generation intense isolated attosecond sources.

Entropy Generation and Human Aging: Lifespan Entropy and Effect of Physical Activity Level

Directory of Open Access Journals (Sweden)

Kalyan Annamalai

2008-06-01

Full Text Available The first and second laws of thermodynamics were applied to biochemical reactions typical of human metabolism. An open-system model was used for a human body. Energy conservation, availability and entropy balances were performed to obtain the entropy generated for the main food components. Quantitative results for entropy generation were obtained as a function of age using the databases from the U.S. Food and Nutrition Board (FNB and Centers for Disease Control and Prevention (CDC, which provide energy requirements and food intake composition as a function of age, weight and stature. Numerical integration was performed through human lifespan for different levels of physical activity. Results were presented and analyzed. Entropy generated over the lifespan of average individuals (natural death was found to be 11,404 kJ/ºK per kg of body mass with a rate of generation three times higher on infants than on the elderly. The entropy generated predicts a life span of 73.78 and 81.61 years for the average U.S. male and female individuals respectively, which are values that closely match the average lifespan from statistics (74.63 and 80.36 years. From the analysis of the effect of different activity levels, it is shown that entropy generated increases with physical activity, suggesting that exercise should be kept to a “healthy minimum” if entropy generation is to be minimized.

Event generator for RHIC spin physics. Proceedings of RIKEN BNL Research Center workshop: Volume 11

International Nuclear Information System (INIS)

1998-01-01

A major objective of the workshop was to establish a firm collaboration to develop suitable event generators for the spin physics program at RHIC. With the completion of the Relativistic Heavy Ion Collider (RHIC) as a polarized collider a completely new domain of high-energy spin physics will be opened. The planned studies address the spin structure of the nucleon, tests of the standard model, and transverse spin effects in initial and final states. RHIC offers the unique opportunity to pursue these studies because of its high and variable energy, 50 ≤ √s ≤ 500 GeV, high polarization, 70%, and high luminosity, 2 x 10 32 cm -2 sec -1 or more at 500 GeV. To maximize the output from the spin program at RHIC, the understanding of both experimental and theoretical systematic errors is crucial. It will require full-fledged event generators, to simulate the processes of interest in great detail. The history of event generators shows that their development and improvement are ongoing processes taking place in parallel to the physics analysis by various experimental groups. The number of processes included in the generators has been increasing and the precision of their predictions is being improved continuously. This workshop aims at getting this process well under way for the spin physics program at RHIC, based on the first development in this direction, SPHINX

Determination of self generated magnetic field and the plasma density using Cotton Mouton polarimetry with two color probes

Directory of Open Access Journals (Sweden)

Joshi A.S.

2013-11-01

Full Text Available Self generated magnetic fields (SGMF in laser produced plasmas are conventionally determined by measuring the Faraday rotation angle of a linearly polarized laser probe beam passing through the plasma along with the interferogram for obtaining plasma density. In this paper, we propose a new method to obtain the plasma density and the SGMF distribution from two simultaneous measurements of Cotton Mouton polarimetry of two linearly polarized probe beams of different colors that pass through plasma in a direction normal to the planar target. It is shown that this technique allows us to determine the distribution of SGMF and the plasma density without doing interferometry of laser produced plasmas.

A novel linear physical model for remote sensing of snow wetness and snow density using the visible and infrared bands

Science.gov (United States)

Varade, D. M.; Dikshit, O.

2017-12-01

Modeling and forecasting of snowmelt runoff are significant for understanding the hydrological processes in the cryosphere which requires timely information regarding snow physical properties such as liquid water content and density of snow in the topmost layer of the snowpack. Both the seasonal runoffs and avalanche forecasting are vastly dependent on the inherent physical characteristics of the snowpack which are conventionally measured by field surveys in difficult terrains at larger impending costs and manpower. With advances in remote sensing technology and the increase in the availability of satellite data, the frequency and extent of these surveys could see a declining trend in future. In this study, we present a novel approach for estimating snow wetness and snow density using visible and infrared bands that are available with most multi-spectral sensors. We define a trapezoidal feature space based on the spectral reflectance in the near infrared band and the Normalized Differenced Snow Index (NDSI), referred to as NIR-NDSI space, where dry snow and wet snow are observed in the left diagonal upper and lower right corners, respectively. The corresponding pixels are extracted by approximating the dry and wet edges which are used to develop a linear physical model to estimate snow wetness. Snow density is then estimated using the modeled snow wetness. Although the proposed approach has used Sentinel-2 data, it can be extended to incorporate data from other multi-spectral sensors. The estimated values for snow wetness and snow density show a high correlation with respect to in-situ measurements. The proposed model opens a new avenue for remote sensing of snow physical properties using multi-spectral data, which were limited in the literature.

Exploring Fluorescent Dyes at Biomimetic Interfaces with Second Harmonic Generation and Molecular Dynamics

Czech Academy of Sciences Publication Activity Database

Licari, G.; Cwiklik, Lukasz; Jungwirth, Pavel; Vauthey, E.

2017-01-01

Roč. 33, č. 14 (2017), s. 3373-3383 ISSN 0743-7463 R&D Projects: GA ČR(CZ) GBP208/12/G016 Institutional support: RVO:61388955 ; RVO:61388963 Keywords : sum-frequency generation * excited-state dynamics * air-water-interface * density-functional theory Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 3.833, year: 2016

Exploring Fluorescent Dyes at Biomimetic Interfaces with Second Harmonic Generation and Molecular Dynamics

Czech Academy of Sciences Publication Activity Database

Licari, G.; Cwiklik, Lukasz; Jungwirth, Pavel; Vauthey, E.

2017-01-01

Roč. 33, č. 14 (2017), s. 3373-3383 ISSN 0743-7463 R&D Projects: GA ČR(CZ) GBP208/12/G016 Institutional support: RVO:61388955 ; RVO:61388963 Keywords : sum -frequency generation * excited-state dynamics * air-water-interface * density-functional theory Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 3.833, year: 2016

Relativistically Self-Channeled Femtosecond Terawatt Lasers for High-Field Physics and X-Ray Generation

Energy Technology Data Exchange (ETDEWEB)

Borisov, A.B.; Boyer, K.; Cameron, S.M.; Luk, T.S.; McPherson, A.; Nelson, T.; Rhodes, C.K.

1999-01-01

Optical channeling or refractive guiding processes involving the nonlinear interaction of intense femtosecond optical pulses with matter in the self-focussing regime has created exciting opportunities for next-generation laser plasma-based x-ray sources and directed energy applications. This fundamentally new form of extended paraxial electromagnetic propagation in nonlinear dispersive media such as underdense plasma is attributed to the interplay between normal optical diffraction and intensity-dependent nonlinear focussing and refraction contributions in the dielectric response. Superposition of these mechanisms on the intrinsic index profile acts to confine the propagating energy in a dynamic self-guiding longitudinal waveguide structure which is stable for power transmission and robust compression. The laser-driven channels are hypothesized to support a degree of solitonic transport behavior, simultaneously stable in the space and time domains (group velocity dispersion balances self-phase modulation), and are believed to be self-compensating for diffraction and dispersion over many Rayleigh lengths in contrast with the defining characteristics of conventional diffractive imaging and beamforming. By combining concentrated power deposition with well-ordered spatial localization, this phenomena will also create new possibilities for production and regulation of physical interactions, including electron beams, enhanced material coupling, and self-modulated plasma wakefields, over extended gain distances with unprecedented energy densities. Harmonious combination of short-pulse x-ray production with plasma channeling resulting from a relativistic charge displacement nonlinearity mechanism in the terawatt regime (10{sup 18} W/cm{sup 2}) has been shown to generate high-field conditions conducive to efficient multi-kilovolt x-ray amplification and peak spectral brightness. Channeled optical propagation with intense short-pulse lasers is expected to impact several

Using Prediction Markets to Generate Probability Density Functions for Climate Change Risk Assessment

Science.gov (United States)

Boslough, M.

2011-12-01

Climate-related uncertainty is traditionally presented as an error bar, but it is becoming increasingly common to express it in terms of a probability density function (PDF). PDFs are a necessary component of probabilistic risk assessments, for which simple "best estimate" values are insufficient. Many groups have generated PDFs for climate sensitivity using a variety of methods. These PDFs are broadly consistent, but vary significantly in their details. One axiom of the verification and validation community is, "codes don't make predictions, people make predictions." This is a statement of the fact that subject domain experts generate results using assumptions within a range of epistemic uncertainty and interpret them according to their expert opinion. Different experts with different methods will arrive at different PDFs. For effective decision support, a single consensus PDF would be useful. We suggest that market methods can be used to aggregate an ensemble of opinions into a single distribution that expresses the consensus. Prediction markets have been shown to be highly successful at forecasting the outcome of events ranging from elections to box office returns. In prediction markets, traders can take a position on whether some future event will or will not occur. These positions are expressed as contracts that are traded in a double-action market that aggregates price, which can be interpreted as a consensus probability that the event will take place. Since climate sensitivity cannot directly be measured, it cannot be predicted. However, the changes in global mean surface temperature are a direct consequence of climate sensitivity, changes in forcing, and internal variability. Viable prediction markets require an undisputed event outcome on a specific date. Climate-related markets exist on Intrade.com, an online trading exchange. One such contract is titled "Global Temperature Anomaly for Dec 2011 to be greater than 0.65 Degrees C." Settlement is based

Generator of an exponential function with respect to time

International Nuclear Information System (INIS)

Janin, Paul; Puyal, Claude.

1981-01-01

This invention deals with an exponential function generator, and an application of this generator to simulating the criticality of a nuclear reactor for reactimeter calibration purposes. This generator, which is particularly suitable for simulating the criticality of a nuclear reactor to calibrate a reactimeter, can also be used in any field of application necessitating the generation of an exponential function in real time. In certain fields of thermodynamics, it is necessary to represent temperature gradients as a function of time. The generator might find applications here. Another application is nuclear physics where it is necessary to represent the attenuation of a neutron flux density with respect to time [fr

Optimal Interpolation scheme to generate reference crop evapotranspiration

Science.gov (United States)

Tomas-Burguera, Miquel; Beguería, Santiago; Vicente-Serrano, Sergio; Maneta, Marco

2018-05-01

We used an Optimal Interpolation (OI) scheme to generate a reference crop evapotranspiration (ETo) grid, forcing meteorological variables, and their respective error variance in the Iberian Peninsula for the period 1989-2011. To perform the OI we used observational data from the Spanish Meteorological Agency (AEMET) and outputs from a physically-based climate model. To compute ETo we used five OI schemes to generate grids for the five observed climate variables necessary to compute ETo using the FAO-recommended form of the Penman-Monteith equation (FAO-PM). The granularity of the resulting grids are less sensitive to variations in the density and distribution of the observational network than those generated by other interpolation methods. This is because our implementation of the OI method uses a physically-based climate model as prior background information about the spatial distribution of the climatic variables, which is critical for under-observed regions. This provides temporal consistency in the spatial variability of the climatic fields. We also show that increases in the density and improvements in the distribution of the observational network reduces substantially the uncertainty of the climatic and ETo estimates. Finally, a sensitivity analysis of observational uncertainties and network densification suggests the existence of a trade-off between quantity and quality of observations.

Impact of Physical Abuse on Internalizing Behavior Across Generations.

Science.gov (United States)

Esteves, Kyle; Gray, Sarah A O; Theall, Katherine P; Drury, Stacy S

2017-10-01

This study investigated the multigenerational impact of mothers' own exposure to physical maltreatment on internalizing symptoms in her child after accounting for her parenting practices, depression, and the child's own exposure to stressful life events. Children ( n = 101, ages 5-16), predominantly African American, were recruited into this cross sectional study using ethnographic mapping and targeted sampling for high-risk neighborhoods. Mothers reported retrospectively on their own exposure to physical maltreatment in childhood, their parenting practices, as well as current depressive symptoms. Maternal report of her child's exposure to stressful life events and child behavior was also collected. Maternal childhood exposure to physical maltreatment was significantly associated with her child's internalizing symptoms ( p = .004); this effect remained after accounting for child sex, maternal depressive symptoms, harsh parenting practices, and the child's own exposure to stressful life events. Formal tests of mediation through these pathways were non-significant. Findings suggest mothers' experience of childhood maltreatment contributes uniquely to children's internalizing symptoms, potentially through previously uncharacterized pathways. Examination of additional behavioral, psychosocial and biological pathways may help better describe the multi-generational effects of child maltreatment.

Physical Modeling of the Processes Responsible for the Mid-Latitude Storm Enhanced Plasma Density

Science.gov (United States)

Fuller-Rowell, T. J.; Maruyama, N.; Fedrizzi, M.; Codrescu, M.; Heelis, R. A.

2016-12-01

Certain magnetic local time sectors at mid latitudes see substantial increases in plasma density in the early phases of a geomagnetic storm. The St. Patrick's Day storms of 2013 and 2015 were no exception, both producing large increases of total electron content at mid latitudes. There are theories for the build up of the storm enhanced density (SED), but can current theoretical ionosphere-thermosphere coupled models actually reproduce the response for an actual event? Not only is it necessary for the physical model to contain the appropriate physics, they also have to be forced by the correct drivers. The SED requires mid-latitude zonal transport to provide plasma stagnation in sunlight to provide the production. The theory also requires a poleward drift perpendicular to the magnetic field to elevate the plasma out of the body of the thermosphere to regions of substantially less loss rate. It is also suggested that equatorward winds are necessary to further elevate the plasma to regions of reduced loss. However, those same winds are also likely to transport molecular nitrogen rich neutral gas equatorward, potentially canceling out the benefits of the neutral circulation. Observations of mid-latitude zonal plasma flow are first analyzed to see if this first necessary ingredient is substantiated. The drift observations are then used to tune the driver to determine if, with the appropriate electric field driver, the latest physical models can reproduce the substantial plasma build up. If it can, the simulation can also be used to assess the contribution of the equatorward meridional wind; are they an asset to the plasma build up, or does the enhanced molecular species they carry counteract their benefit.

Welcome to America, welcome to college: Comparing the effects of immigrant generation and college generation on physical science and engineering career

Science.gov (United States)

Lung, Florin; Potvin, Geoff; Sonnert, Gerhard; Sadler, Philip M.

2013-01-01

Students enter college with social, cultural, and economic resources (well described Bourdieu's concepts of habitus and capital) that significantly impact their goals, actions, and successes. Two important determinants of the amount and type of resources available to students are their immigrant generation and college generation status. Drawing on a national sample of 6860 freshmen enrolled in college English, we compare and contrast the effects of immigrant generation with those of college generation status on physical science and engineering career intentions to explore some of the challenges faced by the first in the family to become an American and/or go to college.

Dark matter and gas density profiles - a consequence of entropy bifurcation

International Nuclear Information System (INIS)

Leubner, M. P.

2006-01-01

The radial profiles of dark matter and hot plasma density distributions of relaxed galaxies and clusters were hitherto commonly fitted by empirical functions. On the other hand, the fundamental concept of non-extensive statistics accounts for long-range interactions and correlations present in gravitationally coupled ensembles and plasmas. We provide a theoretical link of non-extensive statistics to large scale astrophysical structures and show that the underlying tandem character of the entropy results in a bifurcation of the density distribution. A kinetic dark matter and thermodynamic gas branch turn out as natural consequence within the theory and is controlled by one single parameter, measuring physically the degree of correlations in the system. The theoretically derived density profiles are shown to represent accurately the characteristics of both, DM and hot plasma distributions, as observed or generated in N-body and hydro-simulations. The significant advantage over empirical fitting functions is provided by the physical content of the non-extensive approach wherefore it is proposed to model observed density profiles of astrophysical structures within the fundamental context of entropy generalization, accounting for nonlocality and long-range interactions in gravitationally coupled systems

Generation and decay dynamics of triplet excitons in Alq3 thin films under high-density excitation conditions.

Science.gov (United States)

Watanabe, Sadayuki; Furube, Akihiro; Katoh, Ryuzi

2006-08-31

We studied the generation and decay dynamics of triplet excitons in tris-(8-hydroxyquinoline) aluminum (Alq3) thin films by using transient absorption spectroscopy. Absorption spectra of both singlet and triplet excitons in the film were identified by comparison with transient absorption spectra of the ligand molecule (8-hydroxyquinoline) itself and the excited triplet state in solution previously reported. By measuring the excitation light intensity dependence of the absorption, we found that exciton annihilation dominated under high-density excitation conditions. Annihilation rate constants were estimated to be gammaSS = (6 +/- 3) x 10(-11) cm3 s(-1) for single excitons and gammaTT = (4 +/- 2) x 10(-13) cm3 s(-1) for triplet excitons. From detailed analysis of the light intensity dependence of the quantum yield of triplet excitons under high-density conditions, triplet excitons were mainly generated through fission from highly excited singlet states populated by singlet-singlet exciton annihilation. We estimated that 30% of the highly excited states underwent fission.

Density functional theory

International Nuclear Information System (INIS)

Das, M.P.

1984-07-01

The state of the art of the density functional formalism (DFT) is reviewed. The theory is quantum statistical in nature; its simplest version is the well-known Thomas-Fermi theory. The DFT is a powerful formalism in which one can treat the effect of interactions in inhomogeneous systems. After some introductory material, the DFT is outlined from the two basic theorems, and various generalizations of the theorems appropriate to several physical situations are pointed out. Next, various approximations to the density functionals are presented and some practical schemes, discussed; the approximations include an electron gas of almost constant density and an electron gas of slowly varying density. Then applications of DFT in various diverse areas of physics (atomic systems, plasmas, liquids, nuclear matter) are mentioned, and its strengths and weaknesses are pointed out. In conclusion, more recent developments of DFT are indicated

Physical inactivity interacts with an endothelial lipase polymorphism to modulate high density lipoprotein cholesterol in the GOLDN study

Science.gov (United States)

BACKGROUND: Plasma high density lipoprotein (HDL) cholesterol (HDL-C) concentration is highly heritable but is also modifiable by environmental factors including physical activity. HDL-C response to exercise varies among individuals, and this variability may be associated with genetic polymorphism...

Effectiveness and feasibility of lowering playground density during recess to promote physical activity and decrease sedentary time at primary school.

Science.gov (United States)

D'Haese, Sara; Van Dyck, Delfien; De Bourdeaudhuij, Ilse; Cardon, Greet

2013-12-10

This pilot study aimed at investigating the effectiveness of lowering playground density on increasing children's physical activity and decreasing sedentary time. Also the feasibility of this intervention was tested. Data were collected in September and October 2012 in three Belgian schools in 187, 9-12 year old children. During the intervention, playground density was decreased by splitting up recesses and decreasing the number of children sharing the playground. A within-subject design was used. Children wore accelerometers during the study week. Three-level (class - participant - measurement (baseline or intervention)) linear regression models were used to determine intervention effects. After the intervention week the school principals filled out a questionnaire concerning the feasibility of the intervention. The available play space was 12.18 ± 4.19 m²/child at baseline and increased to 24.24 ± 8.51 m²/child during intervention. During the intervention sedentary time decreased (-0.58 min/recess; -3.21%/recess) and moderate-to-vigorous physical activity (+1.04 min/recess; +5.9%/recess) increased during recess and during the entire school day (sedentary time: -3.29%/school day; moderate-to-vigorous physical activity +1.16%/school day). All principals agreed that children enjoyed the intervention; but some difficulties were reported. Lowering playground density can be an effective intervention for decreasing children's sedentary time and increasing their physical activity levels during recess; especially in least active children.

GeneratorSE: A Sizing Tool for Variable-Speed Wind Turbine Generators

Energy Technology Data Exchange (ETDEWEB)

Sethuraman, Latha [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dykes, Katherine L [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-09-22

This report documents a set of analytical models employed by the optimization algorithms within the GeneratorSE framework. The initial values and boundary conditions employed for the generation of the various designs and initial estimates for basic design dimensions, masses, and efficiency for the four different models of generators are presented and compared with empirical data collected from previous studies and some existing commercial turbines. These models include designs applicable for variable-speed, high-torque application featuring direct-drive synchronous generators and low-torque application featuring induction generators. In all of the four models presented, the main focus of optimization is electromagnetic design with the exception of permanent-magnet and wire-wound synchronous generators, wherein the structural design is also optimized. Thermal design is accommodated in GeneratorSE as a secondary attribute by limiting the winding current densities to acceptable limits. A preliminary validation of electromagnetic design was carried out by comparing the optimized magnetic loading against those predicted by numerical simulation in FEMM4.2, a finite-element software for analyzing electromagnetic and thermal physics problems for electrical machines. For direct-drive synchronous generators, the analytical models for the structural design are validated by static structural analysis in ANSYS.

Engineering and physics of high-power-density, compact, reversed-field-pinch fusion reactors

International Nuclear Information System (INIS)

Najmabadi, F.; Conn, R.W.; Krakowski, R.A.; Schultz, K.R.; Steiner, D.

1989-01-01

The technical feasibility and key developmental issues of compact, high-power-density Reversed-Field-Pinch (RFP) reactors are the primary results of the TITAN RFP reactor study. Two design approaches emerged, TITAN-I and TITAN-II, both of which are steady-state, DT-burning, circa 1000 MWe power reactors. The TITAN designs are physically compact and have a high neutron wall loading of 18 MW m 2 . Detailed analyses indicate that: a) each design is technically feasible; b) attractive features of compact RFP reactors can be realized without sacrificing the safety and environmental potential of fusion; and c) major features of this particular embodiment of the RFP reactor are retained in a design window of neutron wall loading ranging from 10 to 20 MW/m 2 . A major product of the TITAN study is the identification and quantification of major engineering and physics requirements for this class of RFP reactors. These findings are the focus of this paper. (author). 26 refs.; 4 figs.; 1 tab

The CERN Super Proton Synchrotron as a tool to study high energy density physics

CERN Document Server

Tahir, N A; Brugger, M; Assmann, R; Shutov, A V; Lomonosov, I V; Piriz, A R; Hoffmann, D H H; Deutsch, C; Fortov3, V E

2008-01-01

An experimental facility named HiRadMat, will be constructed at CERN to study the impact of the 450 GeV c−1 proton beam generated by the Super Proton Synchrotron (SPS) on solid targets. This is designed to study damage caused to the equipment including absorbers, collimators and others in case of an accidental release of the beam energy. This paper presents two-dimensional numerical simulations of target behavior irradiated by the SPS beam. These numerical simulations have shown that the target will be completely destroyed in such an accident, thereby generating high energy density (HED) matter. This study therefore suggests that this facility may also be used for carrying out dedicated experiments to study HED states in matter.

Generation and Active Absorption of 2- and 3-Dimensional Linear Water Waves in Physical Models

DEFF Research Database (Denmark)

Christensen, Morten

in the wave channel in front of the wave generator. The results of physical model tests performed with an absorbing wave maker based on this principle show that the problem of rereflection is reduced significantly when active absorption is performed. Finally, an absorbing directional wave generator for 3-D...... generator is capable of of reducing the problem of rereflection in multidirectional, irregular wave fields significantly....

A method for tuning parameters of Monte Carlo generators and a determination of the unintegrated gluon density

International Nuclear Information System (INIS)

Bacchetta, Alessandro; Jung, Hannes; Kutak, Krzysztof

2010-02-01

A method for tuning parameters in Monte Carlo generators is described and applied to a specific case. The method works in the following way: each observable is generated several times using different values of the parameters to be tuned. The output is then approximated by some analytic form to describe the dependence of the observables on the parameters. This approximation is used to find the values of the parameter that give the best description of the experimental data. This results in significantly faster fitting compared to an approach in which the generator is called iteratively. As an application, we employ this method to fit the parameters of the unintegrated gluon density used in the Cascade Monte Carlo generator, using inclusive deep inelastic data measured by the H1 Collaboration. We discuss the results of the fit, its limitations, and its strong points. (orig.)

The triangular density to approximate the normal density: decision rules-of-thumb

International Nuclear Information System (INIS)

Scherer, William T.; Pomroy, Thomas A.; Fuller, Douglas N.

2003-01-01

In this paper we explore the approximation of the normal density function with the triangular density function, a density function that has extensive use in risk analysis. Such an approximation generates a simple piecewise-linear density function and a piecewise-quadratic distribution function that can be easily manipulated mathematically and that produces surprisingly accurate performance under many instances. This mathematical tractability proves useful when it enables closed-form solutions not otherwise possible, as with problems involving the embedded use of the normal density. For benchmarking purposes we compare the basic triangular approximation with two flared triangular distributions and with two simple uniform approximations; however, throughout the paper our focus is on using the triangular density to approximate the normal for reasons of parsimony. We also investigate the logical extensions of using a non-symmetric triangular density to approximate a lognormal density. Several issues associated with using a triangular density as a substitute for the normal and lognormal densities are discussed, and we explore the resulting numerical approximation errors for the normal case. Finally, we present several examples that highlight simple decision rules-of-thumb that the use of the approximation generates. Such rules-of-thumb, which are useful in risk and reliability analysis and general business analysis, can be difficult or impossible to extract without the use of approximations. These examples include uses of the approximation in generating random deviates, uses in mixture models for risk analysis, and an illustrative decision analysis problem. It is our belief that this exploratory look at the triangular approximation to the normal will provoke other practitioners to explore its possible use in various domains and applications

Physics of steam generators and visit of Saint-Marcel plant

International Nuclear Information System (INIS)

Gillet, N.; Gloaguen, C.; Holcblat, A.; Borsoi, L.; Adobes, A.; David, F.; Greiner, E.; Pascal-Ribot, S.; Gauchet, J.P.; Mercier, L.; Leomy, F.

2004-01-01

This document gathers the transparencies presented at the 6. technical session of the French nuclear energy society (SFEN) in June 2004. The main topic was the physics of steam generators: 1 - description (G. Paudroux, J.Y. Guena, M. Petit); 2 - thermo-hydraulics (A. Holcblat, F. David, S. Pascal-Ribot); 3 - mechanics (N. Gillet, L. Borsoi, A. Adobes); 4 - monitoring and maintenance means (J.P. Gauchet, L. Mercier, F. Leomy); 5 - replacement (C. Gloaguen, E. Greiner). (J.S.)

Expansion Of The Magnetic Flux Density Field In Toroidal Harmonics

CERN Document Server

AUTHOR|(CDS)2290414; Bottura, Luca; Felcini, Enrico

CERN (Conseil Européen pour la Recherche Nucléaire) is recognized worldwide as the main research laboratory in the field of particle physics. Inevitably, all this requires the use of the most advanced technologies, both from the point of view of the instruments and the analytical descriptive methods. One of the numerous potentials of the work carried out at CERN concerns the possibility of exploiting the aforementioned technologies even in contexts distant from the physics of particles, with the result of influencing the technological advancement of many areas. For example, one of the most widely employed theories at CERN, regarding the analytical description of the magnetic flux density inside solenoidal magnets (or approximable as such under suitable assumptions) for the acceleration of particles, is the so-called multipole expansion. This is a two-dimensional or three-dimensional analysis of the distribution of the magnetic flux density generated by the windings of a magnet. The magnet in question ca...

Toward a Redefinition of Density

Science.gov (United States)

Rapoport, Amos

1975-01-01

This paper suggests that in addition to the recent work indicating that crowding is a subjective phenomenon, an adequate definition of density must also include a subjective component since density is a complex phenomenon in itself. Included is a discussion of both physical density and perceived density. (Author/MA)

A physical action potential generator: design, implementation and evaluation.

Science.gov (United States)

Latorre, Malcolm A; Chan, Adrian D C; Wårdell, Karin

2015-01-01

The objective was to develop a physical action potential generator (Paxon) with the ability to generate a stable, repeatable, programmable, and physiological-like action potential. The Paxon has an equivalent of 40 nodes of Ranvier that were mimicked using resin embedded gold wires (Ø = 20 μm). These nodes were software controlled and the action potentials were initiated by a start trigger. Clinically used Ag-AgCl electrodes were coupled to the Paxon for functional testing. The Paxon's action potential parameters were tunable using a second order mathematical equation to generate physiologically relevant output, which was accomplished by varying the number of nodes involved (1-40 in incremental steps of 1) and the node drive potential (0-2.8 V in 0.7 mV steps), while keeping a fixed inter-nodal timing and test electrode configuration. A system noise floor of 0.07 ± 0.01 μV was calculated over 50 runs. A differential test electrode recorded a peak positive amplitude of 1.5 ± 0.05 mV (gain of 40x) at time 196.4 ± 0.06 ms, including a post trigger delay. The Paxon's programmable action potential like signal has the possibility to be used as a validation test platform for medical surface electrodes and their attached systems.

Applications of Robust, Radiation Hard AlGaN Optoelectronic Devices in Space Exploration and High Energy Density Physics

Energy Technology Data Exchange (ETDEWEB)

Sun, K.

2011-05-04

This slide show presents: space exploration applications; high energy density physics applications; UV LED and photodiode radiation hardness; UV LED and photodiode space qualification; UV LED AC charge management; and UV LED satellite payload instruments. A UV LED satellite will be launched 2nd half 2012.

Evaluation of the efficiency and fault density of software generated by code generators

Science.gov (United States)

Schreur, Barbara

1993-01-01

Flight computers and flight software are used for GN&C (guidance, navigation, and control), engine controllers, and avionics during missions. The software development requires the generation of a considerable amount of code. The engineers who generate the code make mistakes and the generation of a large body of code with high reliability requires considerable time. Computer-aided software engineering (CASE) tools are available which generates code automatically with inputs through graphical interfaces. These tools are referred to as code generators. In theory, code generators could write highly reliable code quickly and inexpensively. The various code generators offer different levels of reliability checking. Some check only the finished product while some allow checking of individual modules and combined sets of modules as well. Considering NASA's requirement for reliability, an in house manually generated code is needed. Furthermore, automatically generated code is reputed to be as efficient as the best manually generated code when executed. In house verification is warranted.

Physical phenomena in a low-temperature non-equilibrium plasma and in MHD generators with non-equilibrium conductivity

International Nuclear Information System (INIS)

Velikhov, E.P.; Golubev, V.S.; Dykhne, A.M.

1976-01-01

The paper assesses the position in 1975 of theoretical and experimental work on the physics of a magnetohydrodynamic generator with non-equilibrium plasma conductivity. This research started at the beginning of the 1960s; as work on the properties of thermally non-equilibrium plasma in magnetic fields and also in MHD generator ducts progressed, a number of phenomena were discovered and investigated that had either been unknown in plasma physics or had remained uninvestigated until that time: ionization instability and ionization turbulence of plasma in a magnetic field, acoustic instability of a plasma with anisotropic conductivity, the non-equilibrium ionization wave and the energy balance of a non-equilibrium plasma. At the same time, it was discovered what physical requirements an MHD generator with non-equilibrium conductivity must satisfy to achieve high efficiency in converting the thermal or kinetic energy of the gas flow into electric energy. The experiments on MHD power generation with thermally non-equilibrium plasma carried out up to 1975 indicated that it should be possible to achieve conversion efficiencies of up to 20-30%. (author)

Thermonuclear burst oscillations: where firestorms meet fundamental physics.

CERN Multimedia

CERN. Geneva

2017-01-01

Neutron stars offer a unique environment in which to develop and test theories of the strong force. Densities in neutron star cores can reach up to ten times the density of a normal atomic nucleus, and the stabilising effect of gravitational confinement permits long-timescale weak interactions. This generates matter that is neutron-rich, and opens up the possibility of stable states of strange matter, something that can only exist in neutron stars. Strong force physics is encoded in the Equation of State (EOS), the pressure-density relation, which links to macroscopic observables such as mass M and radius R via the stellar structure equations. By measuring and inverting the M-R relation we can recover the EOS and diagnose the underlying dense matter physics. One very promising technique for simultaneous measurement of M and R exploits hotspots (burst oscillations) that form on the neutron star surface when material accreted from a companion star undergoes a thermonuclear explosion (a Type I X-ray burst). As ...

Meet the Next Generation's Physics Teachers at Physics on Stage

CERN Document Server

2000-01-01

Physics on Stage is an international festival held at CERN where physics teachers from 22 countries will gather to invent new ways of making physics more interesting to students. From 6 to 11 November CERN will be flooded by 450 high school physics teachers from 22 European countries! So don't be surprised if you can't find a place to sit down in the cafeteria! People from Austria, Belgium, Bulgaria, The Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Luxembourg, the Netherlands, Norway, Poland, Portugal, The Slovak Republic, Spain, Sweden, Switzerland and the United Kingdom will come here to show, discuss, and invent new ways of teaching physics and making the subject more interesting for school children and the general public. Indeed the lack of interest in Physics is a worrying concern ­ for example in Germany the number of first year physics students has dropped more than 30 percent in the last ten years! In the UK the number of physics graduates training to be ...

Dependence of current density and intensity of electric field on pulsation of thermodynamic parameters of plasma in the MHD generator

International Nuclear Information System (INIS)

Kapron, H.

1976-01-01

The investigations of pulsation in the MHD generators are described. The influence of termodynamic parameters pulsation on electric parameters of the MHD generator is presented using the method of little disturbances. The results of this investigation are formulas for momentary and average values of: electrical conductivity, the Hall parameter, current density and intensity of electrical field. Analitical investigations were verified by the experiments. (author)

Nanoscale smoothing and the analysis of interfacial charge and dipolar densities

International Nuclear Information System (INIS)

Junquera, Javier; Cohen, Morrel H; Rabe, Karin M

2007-01-01

The interface properties of interest in multilayers include interfacial charge densities, dipole densities, band offsets, and screening lengths, among others. Most such properties are inaccessible to direct measurements, but are key to understanding the physics of the multilayers. They are contained within first-principles electronic structure computations but are buried within the vast amount of quantitative information those computations generate. Thus far, they have been extracted from the numerical data by heuristic nanosmoothing procedures which do not necessarily provide results independent of the smoothing process. In the present paper we develop the theory of nanosmoothing, establishing procedures for both unpolarized and polarized systems which yield interfacial charge and dipole densities and band offsets invariant to the details of the smoothing procedures when the criteria we have established are met. We show also that dipolar charge densities, i.e. the densities of charge transferred across the interface, and screening lengths are not invariant. We illustrate our procedure with a toy model in which real, transversely averaged charge densities are replaced by sums of Gaussians. (topical review)

Physical effects in gravitational field of black holes

International Nuclear Information System (INIS)

Frolov, V.P.

1986-01-01

A large number of problems related to peculiarities of physical processes in a strong gravitational field of black holes has been considered. Energy shift and the complete structure of physical fields for charged sources near a black hole have been investigated. Density matrix and generating functional for quantum effects in stationary black holes have been calculated. Contributions of massless and massive fields to vacuum polarization in black holes have been investigated and influence of quantum effects on the global structure of a black hole has been discussed

Plasma Photonic Devices for High Energy Density Science

International Nuclear Information System (INIS)

Kodama, R.

2005-01-01

High power laser technologies are opening a variety of attractive fields of science and technology using high energy density plasmas such as plasma physics, laboratory astrophysics, material science, nuclear science including medical applications and laser fusion. The critical issues in the applications are attributed to the control of intense light and enormous density of charged particles including efficient generation of the particles such as MeV electrons and protons with a current density of TA/cm2. Now these application possibilities are limited only by the laser technology. These applications have been limited in the control of the high power laser technologies and their optics. However, if we have another device consisted of the 4th material, i.e. plasma, we will obtain a higher energy density condition and explore the application possibilities, which could be called high energy plasma device. One of the most attractive devices has been demonstrated in the fast ignition scheme of the laser fusion, which is cone-guiding of ultra-intense laser light in to high density regions1. This is one of the applications of the plasma device to control the ultra-intense laser light. The other role of the devices consisted of transient plasmas is control of enormous energy-density particles in a fashion analogous to light control with a conventional optical device. A plasma fibre (5?m/1mm), as one example of the devices, has guided and deflected the high-density MeV electrons generated by ultra-intense laser light 2. The electrons have been well collimated with either a lens-like plasma device or a fibre-like plasma, resulting in isochoric heating and creation of ultra-high pressures such as Giga bar with an order of 100J. Plasmas would be uniquely a device to easily control the higher energy density particles like a conventional optical device as well as the ultra-intense laser light, which could be called plasma photonic device. (Author)

Benchmark problem suite for reactor physics study of LWR next generation fuels

International Nuclear Information System (INIS)

Yamamoto, Akio; Ikehara, Tadashi; Ito, Takuya; Saji, Etsuro

2002-01-01

This paper proposes a benchmark problem suite for studying the physics of next-generation fuels of light water reactors. The target discharge burnup of the next-generation fuel was set to 70 GWd/t considering the increasing trend in discharge burnup of light water reactor fuels. The UO 2 and MOX fuels are included in the benchmark specifications. The benchmark problem consists of three different geometries: fuel pin cell, PWR fuel assembly and BWR fuel assembly. In the pin cell problem, detailed nuclear characteristics such as burnup dependence of nuclide-wise reactivity were included in the required calculation results to facilitate the study of reactor physics. In the assembly benchmark problems, important parameters for in-core fuel management such as local peaking factors and reactivity coefficients were included in the required results. The benchmark problems provide comprehensive test problems for next-generation light water reactor fuels with extended high burnup. Furthermore, since the pin cell, the PWR assembly and the BWR assembly problems are independent, analyses of the entire benchmark suite is not necessary: e.g., the set of pin cell and PWR fuel assembly problems will be suitable for those in charge of PWR in-core fuel management, and the set of pin cell and BWR fuel assembly problems for those in charge of BWR in-core fuel management. (author)

Grid-generated He II turbulence in a finite channel - experiment

International Nuclear Information System (INIS)

Niemela, J.J.; Skrbek, L.; Stalp, S.R.

2001-01-01

We present experimental data on decaying turbulence, generated by towing a grid through a stationary sample of He II. We describe in detail the experimental apparatus and physical principles that allow observation of up to six orders of magnitude of decaying vortex line density over three orders of magnitude in time using the second sound attenuation technique. (orig.)

A Methodology for Physical Interconnection Decisions of Next Generation Transport Networks

DEFF Research Database (Denmark)

Gutierrez Lopez, Jose Manuel; Riaz, M. Tahir; Madsen, Ole Brun

2011-01-01

of possibilities when designing the physical network interconnection. This paper develops and presents a methodology in order to deal with aspects related to the interconnection problem of optical transport networks. This methodology is presented as independent puzzle pieces, covering diverse topics going from......The physical interconnection for optical transport networks has critical relevance in the overall network performance and deployment costs. As telecommunication services and technologies evolve, the provisioning of higher capacity and reliability levels is becoming essential for the proper...... development of Next Generation Networks. Currently, there is a lack of specific procedures that describe the basic guidelines to design such networks better than "best possible performance for the lowest investment". Therefore, the research from different points of view will allow a broader space...

Within and between generation phenotypic plasticity in trichome density of Mimulus guttatus.

Science.gov (United States)

Holeski, L M

2007-11-01

Mimulus guttatus (yellow monkeyflower) frequently produce glandular trichomes, a trait that may resist herbivory. Constitutive production of trichomes is variable both within and among populations of M. guttatus and most of this variation is genetic. This study demonstrates that damage on early leaves can induce increased trichome production on later leaves, a plastic response that is likely adaptive. Moreover, this study shows that this induction can be maternally transmitted, increasing trichome density in progeny before they experience herbivory. This transgenerational response must involve a yet undescribed epigenetic mechanism. These experiments also show genetic variation among plants in the capacity for both within and between plant generation induction. Despite the clear evolutionary importance of variation in constitutive and induced herbivory-resistance traits, few other studies have noted genetic variation in both within a plant species.

Bone mineral density across a range of physical activity volumes: NHANES 2007-2010.

Science.gov (United States)

Whitfield, Geoffrey P; Kohrt, Wendy M; Pettee Gabriel, Kelley K; Rahbar, Mohammad H; Kohl, Harold W

2015-02-01

The association between aerobic physical activity volume and bone mineral density (BMD) is not completely understood. The purpose of this study was to clarify the association between BMD and aerobic activity across a broad range of activity volumes, particularly volumes between those recommended in the 2008 Physical Activity Guidelines for Americans and those of trained endurance athletes. Data from the 2007-2010 National Health and Nutrition Examination Survey were used to quantify the association between reported physical activity and BMD at the lumbar spine and proximal femur across the entire range of activity volumes reported by US adults. Participants were categorized into multiples of the minimum guideline-recommended volume based on reported moderate- and vigorous-intensity leisure activity. Lumbar and proximal femur BMD were assessed with dual-energy x-ray absorptiometry. Among women, multivariable-adjusted linear regression analyses revealed no significant differences in lumbar BMD across activity categories, whereas proximal femur BMD was significantly higher among those who exceeded the guidelines by 2-4 times than those who reported no activity. Among men, multivariable-adjusted BMD at both sites neared its highest values among those who exceeded the guidelines by at least 4 times and was not progressively higher with additional activity. Logistic regression estimating the odds of low BMD generally echoed the linear regression results. The association between physical activity volume and BMD is complex. Among women, exceeding guidelines by 2-4 times may be important for maximizing BMD at the proximal femur, whereas among men, exceeding guidelines by ≥4 times may be beneficial for lumbar and proximal femur BMD.

Production of ultrahigh ion current densities at skin-layer subrelativistic laser-plasma interaction

Energy Technology Data Exchange (ETDEWEB)

Badziak, J [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Glowacz, S [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Jablonski, S [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Parys, P [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Wolowski, J [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Hora, H [Department of Theoretical Physics, University of New South Wales, Sydney (Australia); Krasa, J [Institute of Physics, ASCR, Prague (Czech Republic); Laska, L [Institute of Physics, ASCR, Prague (Czech Republic); Rohlena, K [Institute of Physics, ASCR, Prague (Czech Republic)

2004-12-01

Some applications of fast ions driven by a short ({<=}1 ps) laser pulse (e.g. fast ignition of ICF targets, x-ray laser pumping, laboratory astrophysics research or some nuclear physics experiments) require ion beams of picosecond (or shorter) time durations and of very high ion current densities ({approx}10{sup 10} A cm{sup -2} or higher). A possible way of producing ion beams with such extreme parameters is ballistic focusing of fast ions generated by a target normal sheath acceleration (TNSA) mechanism at relativistic laser intensities. In this paper we discuss another method, where the production of short-pulse ion beams of ultrahigh current densities is possible in a planar geometry at subrelativistic laser intensities and at a low energy ({<=}1 J) of the laser pulse. This method-referred to as skin-layer ponderomotive acceleration (S-LPA)-uses strong ponderomotive forces induced at the skin-layer interaction of a short laser pulse with a proper preplasma layer in front of a solid target. The basic features of the high-current ion generation by S-LPA were investigated using a simplified theory, numerical hydrodynamic simulations and measurements. The experiments were performed with subjoule 1 ps laser pulses interacting with massive or thin foil targets at intensities of up to 2 x 10{sup 17} W cm{sup -2}. It was found that both in the backward and forward directions highly collimated high-density ion beams (plasma blocks) with current densities at the ion source (close to the target) approaching 10{sup 10} A cm{sup -2} are produced, in accordance with the theory and numerical calculations. These ion current densities were found to be comparable to (or even higher than) those estimated from recent short-pulse TNSA experiments with relativistic laser intensities. Apart from the simpler physics of the laser-plasma interaction, the advantage of the considered method is the low energy of the driving laser pulses allowing the production of ultrahigh-current-density

Generation of initial geometries for the simulation of the physical system in the DualPHYsics code

International Nuclear Information System (INIS)

Segura Q, E.

2013-01-01

In the diverse research areas of the Instituto Nacional de Investigaciones Nucleares (ININ) are different activities related to science and technology, one of great interest is the study and treatment of the collection and storage of radioactive waste. Therefore at ININ the draft on the simulation of the pollutants diffusion in the soil through a porous medium (third stage) has this problem inherent aspects, hence a need for such a situation is to generate the initial geometry of the physical system For the realization of the simulation method is implemented smoothed particle hydrodynamics (SPH). This method runs in DualSPHysics code, which has great versatility and ability to simulate phenomena of any physical system where hydrodynamic aspects combine. In order to simulate a physical system DualSPHysics code, you need to preset the initial geometry of the system of interest, then this is included in the input file of the code. The simulation sets the initial geometry through regular geometric bodies positioned at different points in space. This was done through a programming language (Fortran, C + +, Java, etc..). This methodology will provide the basis to simulate more complex geometries future positions and form. (Author)

Physical activity and bone: The importance of the various mechanical stimuli for bone mineral density. A review

Directory of Open Access Journals (Sweden)

Bente Morseth

2011-08-01

Full Text Available Numerous studies have reported benefits of regular physical activity on bone mineral density (BMD. The effects of physical activity on BMD are primarily linked to the mechanisms of mechanical loading, but the understanding of the precise mechanism behind the association is incomplete. The aim of this paper was to review the main findings concerning sources and types of mechanical stimuli in relation to BMD. Mechanical forces that act on bone are generated from impact with the ground (ground-reaction forces and from skeletal muscle contractions (muscle forces or muscle-joint forces, but the relative importance of these two sources has not been elucidated. Both muscle-joint forces and gravitational forces seem to be able to induce bone adaptation independently, and there may be differences in the importance of loading sources at different skeletal sites. The nature of the stimuli is affected by the type, intensity, frequency, and duration of the activity. The activity should be dynamic, not static, and the magnitude and rate of the stimuli should be high. In accordance with this, cross-sectional studies report highest BMD in athletes of high-impact activities such as dancing, soccer, volleyball, basketball, squash, speed skating, gymnastics, hockey, and step-aerobics. Endurance activities such as orienteering, skiing, and triathlon seem to be beneficial to a lesser degree, whereas low-impact activities such as swimming and cycling are associated with lower BMD than controls. Both the intensity and frequency of the activity should be varied and increased beyond the habitual level. Duration of the activity seems to be less important, and a few loading cycles seem to be sufficient.

Molecular surface mesh generation by filtering electron density map.

Science.gov (United States)

Giard, Joachim; Macq, Benoît

2010-01-01

Bioinformatics applied to macromolecules are now widely spread and in continuous expansion. In this context, representing external molecular surface such as the Van der Waals Surface or the Solvent Excluded Surface can be useful for several applications. We propose a fast and parameterizable algorithm giving good visual quality meshes representing molecular surfaces. It is obtained by isosurfacing a filtered electron density map. The density map is the result of the maximum of Gaussian functions placed around atom centers. This map is filtered by an ideal low-pass filter applied on the Fourier Transform of the density map. Applying the marching cubes algorithm on the inverse transform provides a mesh representation of the molecular surface.

Molecular Surface Mesh Generation by Filtering Electron Density Map

Directory of Open Access Journals (Sweden)

Joachim Giard

2010-01-01

Full Text Available Bioinformatics applied to macromolecules are now widely spread and in continuous expansion. In this context, representing external molecular surface such as the Van der Waals Surface or the Solvent Excluded Surface can be useful for several applications. We propose a fast and parameterizable algorithm giving good visual quality meshes representing molecular surfaces. It is obtained by isosurfacing a filtered electron density map. The density map is the result of the maximum of Gaussian functions placed around atom centers. This map is filtered by an ideal low-pass filter applied on the Fourier Transform of the density map. Applying the marching cubes algorithm on the inverse transform provides a mesh representation of the molecular surface.

Anosov C-systems and random number generators

Science.gov (United States)

Savvidy, G. K.

2016-08-01

We further develop our previous proposal to use hyperbolic Anosov C-systems to generate pseudorandom numbers and to use them for efficient Monte Carlo calculations in high energy particle physics. All trajectories of hyperbolic dynamical systems are exponentially unstable, and C-systems therefore have mixing of all orders, a countable Lebesgue spectrum, and a positive Kolmogorov entropy. These exceptional ergodic properties follow from the C-condition introduced by Anosov. This condition defines a rich class of dynamical systems forming an open set in the space of all dynamical systems. An important property of C-systems is that they have a countable set of everywhere dense periodic trajectories and their density increases exponentially with entropy. Of special interest are the C-systems defined on higher-dimensional tori. Such C-systems are excellent candidates for generating pseudorandom numbers that can be used in Monte Carlo calculations. An efficient algorithm was recently constructed that allows generating long C-system trajectories very rapidly. These trajectories have good statistical properties and can be used for calculations in quantum chromodynamics and in high energy particle physics.

Next-generation batteries and fuel cells for commercial, military, and space applications

CERN Document Server

Jha, A R

2012-01-01

Distilling complex theoretical physical concepts into an understandable technical framework, Next-Generation Batteries and Fuel Cells for Commercial, Military, and Space Applications describes primary and secondary (rechargeable) batteries for various commercial, military, spacecraft, and satellite applications for covert communications, surveillance, and reconnaissance missions. It emphasizes the cost, reliability, longevity, and safety of the next generation of high-capacity batteries for applications where high energy density, minimum weight and size, and reliability in harsh conditions are

Volume generation of negative ions in high density hydrogen discharges

International Nuclear Information System (INIS)

Hiskes, J.R.; Karo, A.M.

1983-01-01

A parametric survey is made of a high-density tandem two-chamber hydrogen negative ion system. The optimum extracted negative ion current densities are sensitive to the atom concentration in the discharge and to the system scale length. For scale lengths ranging from 10 cm to 0.1 cm optimum current densities range from of order 1 to 100 mA cm -2 , respectively

Design and development of a low cost, high current density power supply for streamer free atmospheric pressure DBD plasma generation in air.

Science.gov (United States)

Jain, Vishal; Visani, Anand; Srinivasan, R; Agarwal, Vivek

2018-03-01

This paper presents a new power supply architecture for generating a uniform dielectric barrier discharge (DBD) plasma in air medium at atmospheric pressure. It is quite a challenge to generate atmospheric pressure uniform glow discharge plasma, especially in air. This is because air plasma needs very high voltage for initiation of discharge. If the high voltage is used along with high current density, it leads to the formation of streamers, which is undesirable for most applications like textile treatment, etc. Researchers have tried to generate high-density plasma using a RF source, nanosecond pulsed DC source, and medium frequency AC source. However, these solutions suffer from low current discharge and low efficiency due to the addition of an external resistor to control the discharge current. Moreover, they are relatively costly and bulky. This paper presents a new power supply configuration which is very compact and generates high average density (∼0.28 W/cm 2 ) uniform glow DBD plasma in air at atmospheric pressure. The efficiency is also higher as no external resistor is required to control the discharge current. An inherent feature of this topology is that it can drive higher current oscillations (∼50 A peak and 2-3 MHz frequency) into the plasma that damp out due to the plasma dissipation only. A newly proposed model has been used with experimental validation in this paper. Simulations and experimental validation of the proposed topology are included. Also, the application of the generated plasma for polymer film treatment is demonstrated.

Density-ratio effects on buoyancy-driven variable-density turbulent mixing

Science.gov (United States)

Aslangil, Denis; Livescu, Daniel; Banerjee, Arindam

2017-11-01

Density-ratio effects on the turbulent mixing of two incompressible, miscible fluids with different densities subject to constant acceleration are studied by means of high-resolution Direct Numerical Simulations. In a triply periodic domain, turbulence is generated by stirring in response to the differential buoyancy forces within the flow. Later, as the fluids become molecularly mixed, dissipation starts to overcome turbulence generation by bouyancy. Thus, the flow evolution includes both turbulence growth and decay, and it displays features present in the core region of the mixing layer of the Rayleigh-Taylor as well as Richtmyer-Meshkov instabilities. We extend the previous studies by investigating a broad range of density-ratio, from 1-14.4:1, corresponding to Atwood numbers of 0.05-0.87. Here, we focus on the Atwood number dependence of mixing-efficiency, that is defined based on the energy-conversion ratios from potential energy to total and turbulent kinetic energies, the decay characteristics of buoyancy-assisted variable-density homogeneous turbulence, and the effects of high density-ratios on the turbulence structure and mixing process. Authors acknowledge financial support from DOE-SSAA (DE-NA0003195) and NSF CAREER (#1453056) awards.

Physical activity level of three generation families. Genetic and environmental factors

Directory of Open Access Journals (Sweden)

Raquel Nichele de Chaves

2010-09-01

Full Text Available This study aims (1 to investigate the presence of familial aggregation in physical activity (PA levels and sedentary behavior (SB among members of three generations families and (2 to estimate the magnitude of additive genetic influences on PA and SB phenotypes. The sample consisted of 100 extended families covering three generations (n=1034, from the Lisbon area, Portugal. Phenotypes were assessed via the short version of the self-administered International Physical Activity Questionnaire (IPAQ-SF. Measured phenotypes: total physical activity (TPA; vigorous (VPA; moderate (MPA; walking; time spent in sitting time (ST, watching television (WT and PA levels classification. Body mass index (BMI was calculated. Exploratory family analysis in all phenotypes was conducted in PEDSTATS software. The genetic component (h2 and shared environmental effect were estimated using maximum likelihood implemented in the SOLAR software package. All graphs were done in HLM software. Sex, age, sex*age, age2, sex*age2 and BMI were used as covariates. Significant level was set at 0,05. Genetic component estimates (h2 were as follows: TPA h2=0,28±0,06 (p<0.0001; VPA h2=0,35±0,06 (p<0.0001; MPA h2=0,29±0,06 (p<0.0001; walking h2=0,40±0,06 (p<0.0001; ST h2=0,29±0,06 (p<0.0001; WT h2=0,15±0,06 (p<0.003 and determination of the level physical activity h2=0,35±0,14 (p<0.007. Shared environmental effect was not significant. These results showed a low-to-moderate genetic contribution, between 15% to 40% of the total variability, in the PA and SB phenotypes. The genetic factors have low to moderate influence in this sample. Non-shared environmental factors appear to have the major contribution in these phenotypes.

Stone crayfish in the Czech Republic: how does its population density depend on basic chemical and physical properties of water?

Directory of Open Access Journals (Sweden)

Vlach P.

2013-03-01

Full Text Available The stone crayfish (Austropotamobius torrentium Schrank is one of the two native crayfish species in the Czech Republic. The populations as well as physical and chemical parameters of water (pH, conductivity, dissolved oxygen, undissolved particles, NH3, NH4+, NO2−, NO3−, phosphorus, Ca2+ and SO42 −  of 33 streams were examined to find the ecological plasticity of this crayfish and some relations between these parameters and population densities. The mentioned parameters often significantly varied at the sites. Two approaches were applied to find relations between these parameters and observed abundance. At first, the observed streams were compared using RDA (streams  ×  physical-chemical parameters. No significance was found while testing relationship between the streams grouped along the 1st axis of model and the observed abundances of stone crayfish. However, some correlations between abundance and conductivity, calcium, nitrates and sulphates were found using polynomial regression. These relationships are explicable in terms of mutual correlations, underlying geology and other factors which affect abundances. In conclusion, A. torrentium is able to inhabit waters with a large range of physical and chemical parameters of the water without any fundamental influence on population densities. Water properties play an indisputable role as limiting ecological factors at uncommon concentrations, but population densities are probably influenced much more by the types of habitats, habitat features, predation and other ecological factors.

P3: An installation for high-energy density plasma physics and ultra-high intensity laser–matter interaction at ELI-Beamlines

Czech Academy of Sciences Publication Activity Database

Weber, Stefan A.; Bechet, Sabrina; Borneis, S.; Brabec, Lukáš; Bučka, Martin; Chacon-Golcher, Edwin; Ciappina, Marcelo F.; De Marco, Massimo; Fajstavr, Antonín; Falk, Kateřina; Garcia, E.-R.; Grosz, Jakub; Gu, Yanjun; Hernandez Martin, Juan C.; Holec, M.; Janečka, Pavel; Jantač, Martin; Jirka, Martin; Kadlecová, Hedvika; Khikhlukha, Danila; Klimo, Ondřej; Korn, Georg; Kramer, Daniel; Batheja, Deepak Kumar; Laštovička, Tomáš; Lutoslawski, P.; Morejon, L.; Olšovcová, Veronika; Rajdl, Marek; Renner, Oldřich; Rus, Bedřich; Singh, Sushil K.; Šmíd, Michal; Sokol, Martin; Versaci, Roberto; Vrána, Roman; Vranic, M.; Vyskočil, Jiří; Wolf, Adam; Yu, Q.

2017-01-01

Roč. 2, č. 4 (2017), s. 149-176 E-ISSN 2468-080X R&D Projects: GA MŠk LQ1606; GA MŠk LM2015065; GA MŠk EF15_008/0000162; GA MŠk EF15_003/0000449 Grant - others:ELI Beamlines(XE) CZ.02.1.01/0.0/0.0/15_008/0000162; OP VVV - HiFi(XE) CZ.02.1.01/0.0/0.0/15_003/0000449 Institutional support: RVO:68378271 Keywords : high-energy-density- physics * ultra-high-intensity * warm dense matter * laboratory astrophysics * high repetition rate lasers * plasma optics * inertial confinement fusion Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics )

Principal component analysis of the CT density histogram to generate parametric response maps of COPD

Science.gov (United States)

Zha, N.; Capaldi, D. P. I.; Pike, D.; McCormack, D. G.; Cunningham, I. A.; Parraga, G.

2015-03-01

Pulmonary x-ray computed tomography (CT) may be used to characterize emphysema and airways disease in patients with chronic obstructive pulmonary disease (COPD). One analysis approach - parametric response mapping (PMR) utilizes registered inspiratory and expiratory CT image volumes and CT-density-histogram thresholds, but there is no consensus regarding the threshold values used, or their clinical meaning. Principal-component-analysis (PCA) of the CT density histogram can be exploited to quantify emphysema using data-driven CT-density-histogram thresholds. Thus, the objective of this proof-of-concept demonstration was to develop a PRM approach using PCA-derived thresholds in COPD patients and ex-smokers without airflow limitation. Methods: Fifteen COPD ex-smokers and 5 normal ex-smokers were evaluated. Thoracic CT images were also acquired at full inspiration and full expiration and these images were non-rigidly co-registered. PCA was performed for the CT density histograms, from which the components with the highest eigenvalues greater than one were summed. Since the values of the principal component curve correlate directly with the variability in the sample, the maximum and minimum points on the curve were used as threshold values for the PCA-adjusted PRM technique. Results: A significant correlation was determined between conventional and PCA-adjusted PRM with 3He MRI apparent diffusion coefficient (p<0.001), with CT RA950 (p<0.0001), as well as with 3He MRI ventilation defect percent, a measurement of both small airways disease (p=0.049 and p=0.06, respectively) and emphysema (p=0.02). Conclusions: PRM generated using PCA thresholds of the CT density histogram showed significant correlations with CT and 3He MRI measurements of emphysema, but not airways disease.

Real time estimation of generation, extinction and flow of muscle fibre action potentials in high density surface EMG.

Science.gov (United States)

Mesin, Luca

2015-02-01

Developing a real time method to estimate generation, extinction and propagation of muscle fibre action potentials from bi-dimensional and high density surface electromyogram (EMG). A multi-frame generalization of an optical flow technique including a source term is considered. A model describing generation, extinction and propagation of action potentials is fit to epochs of surface EMG. The algorithm is tested on simulations of high density surface EMG (inter-electrode distance equal to 5mm) from finite length fibres generated using a multi-layer volume conductor model. The flow and source term estimated from interference EMG reflect the anatomy of the muscle, i.e. the direction of the fibres (2° of average estimation error) and the positions of innervation zone and tendons under the electrode grid (mean errors of about 1 and 2mm, respectively). The global conduction velocity of the action potentials from motor units under the detection system is also obtained from the estimated flow. The processing time is about 1 ms per channel for an epoch of EMG of duration 150 ms. A new real time image processing algorithm is proposed to investigate muscle anatomy and activity. Potential applications are proposed in prosthesis control, automatic detection of optimal channels for EMG index extraction and biofeedback. Copyright © 2014 Elsevier Ltd. All rights reserved.

The relationship between BPAQ-derived physical activity and bone density of middle-aged and older men.

Science.gov (United States)

Bolam, K A; Beck, B R; Adlard, K N; Skinner, T L; Cormie, P; Galvão, D A; Spry, N; Newton, R U; Taaffe, D R

2014-11-01

The bone-specific physical activity questionnaire (BPAQ) accounts for activities that affect bone but has not been used in studies with older adults. Relationships exist between the BPAQ-derived physical activity and bone density in healthy middle-aged and older men but not men with prostate cancer. Disease-related treatments detrimental to bone should be considered when administering the BPAQ. The bone-specific physical activity questionnaire (BPAQ) was developed to account for bone-specific loading. In this retrospective study, we examined the relationship between BPAQ-derived physical activity and bone mineral density (BMD) in middle-aged and older men with and without prostate cancer. Two groups, 36 healthy men and 69 men with prostate cancer receiving androgen suppression therapy (AST), completed the BPAQ and had whole body, total hip, femoral (FN) and lumbar spine BMD assessed by dual-energy X-ray absorptiometry. Past (pBPAQ), current (cBPAQ) and total BPAQ (tBPAQ) scores for the healthy men were related to FN BMD (pBPAQ r = 0.36, p = 0.030; cBPAQ r s = 0.35, p = 0.034; tBPAQ r = 0.41, p = 0.014), and pBPAQ and tBPAQ were related to total hip (r s = 0.35, p = 0.035 and r s = 0.36, p = 0.029, respectively) and whole body BMD (r s = 0.44, p = 0.007 and r s = 0.45, p = 0.006, respectively). In men with prostate cancer, the BPAQ was not significantly associated with BMD. In stepwise regression analyses, body mass and tBPAQ predicted 30 % of the variance in total hip BMD (p = 0.003), cBPAQ predicted 14 % of the variance in FN BMD (p = 0.002), and body mass, age and tBPAQ predicted 47% of the variance in whole body BMD (p men. In men with prostate cancer, the BPAQ was not an independent predictor of BMD. Although BPAQ-derived estimates of physical activity are related to bone status in healthy middle-aged and older men, the adverse effect of AST on bone appears to obscure this relationship in men

Spin-Density Functionals from Current-Density Functional Theory and Vice Versa: A Road towards New Approximations

International Nuclear Information System (INIS)

Capelle, K.; Gross, E.

1997-01-01

It is shown that the exchange-correlation functional of spin-density functional theory is identical, on a certain set of densities, with the exchange-correlation functional of current-density functional theory. This rigorous connection is used to construct new approximations of the exchange-correlation functionals. These include a conceptually new generalized-gradient spin-density functional and a nonlocal current-density functional. copyright 1997 The American Physical Society

The dynamics of variable-density turbulence

International Nuclear Information System (INIS)

Sandoval, D.L.

1995-11-01

The dynamics of variable-density turbulent fluids are studied by direct numerical simulation. The flow is incompressible so that acoustic waves are decoupled from the problem, and implying that density is not a thermodynamic variable. Changes in density occur due to molecular mixing. The velocity field, is in general, divergent. A pseudo-spectral numerical technique is used to solve the equations of motion. Three-dimensional simulations are performed using a grid size of 128 3 grid points. Two types of problems are studied: (1) the decay of isotropic, variable-density turbulence, and (2) buoyancy-generated turbulence in a fluid with large density fluctuations. In the case of isotropic, variable-density turbulence, the overall statistical decay behavior, for the cases studied, is relatively unaffected by the presence of density variations when the initial density and velocity fields are statistically independent. The results for this case are in quantitative agreement with previous numerical and laboratory results. In this case, the initial density field has a bimodal probability density function (pdf) which evolves in time towards a Gaussian distribution. The pdf of the density field is symmetric about its mean value throughout its evolution. If the initial velocity and density fields are statistically dependent, however, the decay process is significantly affected by the density fluctuations. For the case of buoyancy-generated turbulence, variable-density departures from the Boussinesq approximation are studied. The results of the buoyancy-generated turbulence are compared with variable-density model predictions. Both a one-point (engineering) model and a two-point (spectral) model are tested against the numerical data. Some deficiencies in these variable-density models are discussed and modifications are suggested

Physics of the early universe

International Nuclear Information System (INIS)

Brandenberger, R.H.

1987-01-01

When studying the evolution of the very early universe it is necessary to use a description of matter which is appropriate at very high energies, namely in terms of quantum fields. In such models there may be a period during which the ratio of pressure and energy density is - 1, an equation of state which leads to an exponential expansion of the universe (inflation). There may also arise stable topological defects similar to vortex lines in condensed matter physics. These defects (cosmic strings) form seeds about which gas can accrete to form galaxies and clusters of galaxies. The author reviews inflation and cosmic strings, emphasizing their role in generating the energy density perturbations which are required in order to explain the existence of structures in the universe

Digital Generation of Noise-Signals with Arbitrary Constant or Time-Varying Spectra (A noise generation software package and its application)

CERN Document Server

Tückmantel, Joachim

2008-01-01

Artificial creation of arbitrary noise signals is used in accelerator physics to reproduce a measured perturbation spectrum for simulations but also to generate real-time shaped noise spectra for controlled emittance blow-up giving tailored properties to the final bunch shape. It is demonstrated here how one can produce numerically what is, for all practical purposes, an unlimited quantity of non-periodic noise data having any predefined spectral density. This spectral density may be constant or varying with time. The noise output never repeats and has excellent statistical properties, important for very long-term applications. It is difficult to obtain such flexibility and spectral cleanliness using analogue techniques. This algorithm was applied both in computer simulations of bunch behaviour in the presence of RF noise in the PS, SPS and LHC and also to generate real-time noise, tracking the synchrotron frequency change during the energy ramp of the SPS and producing controlled longitudinal emittance blow-...

Sufficient conditions for positivity of non-Markovian master equations with Hermitian generators

International Nuclear Information System (INIS)

Wilkie, Joshua; Wong Yinmei

2009-01-01

We use basic physical motivations to develop sufficient conditions for positive semidefiniteness of the reduced density matrix for generalized non-Markovian integrodifferential Lindblad-Kossakowski master equations with Hermitian generators. We show that it is sufficient for the memory function to be the Fourier transform of a real positive symmetric frequency density function with certain properties. These requirements are physically motivated, and are more general and more easily checked than previously stated sufficient conditions. We also explore the decoherence dynamics numerically for some simple models using the Hadamard representation of the propagator. We show that the sufficient conditions are not necessary conditions. We also show that models exist in which the long time limit is in part determined by non-Markovian effects

Ground-state densities from the Rayleigh-Ritz variation principle and from density-functional theory.

Science.gov (United States)

Kvaal, Simen; Helgaker, Trygve

2015-11-14

The relationship between the densities of ground-state wave functions (i.e., the minimizers of the Rayleigh-Ritz variation principle) and the ground-state densities in density-functional theory (i.e., the minimizers of the Hohenberg-Kohn variation principle) is studied within the framework of convex conjugation, in a generic setting covering molecular systems, solid-state systems, and more. Having introduced admissible density functionals as functionals that produce the exact ground-state energy for a given external potential by minimizing over densities in the Hohenberg-Kohn variation principle, necessary and sufficient conditions on such functionals are established to ensure that the Rayleigh-Ritz ground-state densities and the Hohenberg-Kohn ground-state densities are identical. We apply the results to molecular systems in the Born-Oppenheimer approximation. For any given potential v ∈ L(3/2)(ℝ(3)) + L(∞)(ℝ(3)), we establish a one-to-one correspondence between the mixed ground-state densities of the Rayleigh-Ritz variation principle and the mixed ground-state densities of the Hohenberg-Kohn variation principle when the Lieb density-matrix constrained-search universal density functional is taken as the admissible functional. A similar one-to-one correspondence is established between the pure ground-state densities of the Rayleigh-Ritz variation principle and the pure ground-state densities obtained using the Hohenberg-Kohn variation principle with the Levy-Lieb pure-state constrained-search functional. In other words, all physical ground-state densities (pure or mixed) are recovered with these functionals and no false densities (i.e., minimizing densities that are not physical) exist. The importance of topology (i.e., choice of Banach space of densities and potentials) is emphasized and illustrated. The relevance of these results for current-density-functional theory is examined.

Steam generators clogging diagnosis through physical and statistical modelling

International Nuclear Information System (INIS)

Girard, S.

2012-01-01

Steam generators are massive heat exchangers feeding the turbines of pressurised water nuclear power plants. Internal parts of steam generators foul up with iron oxides which gradually close some holes aimed for the passing of the fluid. This phenomenon called clogging causes safety issues and means to assess it are needed to optimise the maintenance strategy. The approach investigated in this thesis is the analysis of steam generators dynamic behaviour during power transients with a mono dimensional physical model. Two improvements to the model have been implemented. One was taking into account flows orthogonal to the modelling axis, the other was introducing a slip between phases accounting for velocity difference between liquid water and steam. These two elements increased the model's degrees of freedom and improved the adequacy of the simulation to plant data. A new calibration and validation methodology has been proposed to assess the robustness of the model. The initial inverse problem was ill posed: different clogging spatial configurations can produce identical responses. The relative importance of clogging, depending on its localisation, has been estimated by sensitivity analysis with the Sobol' method. The dimension of the model functional output had been previously reduced by principal components analysis. Finally, the input dimension has been reduced by a technique called sliced inverse regression. Based on this new framework, a new diagnosis methodology, more robust and better understood than the existing one, has been proposed. (author)

The HepMC C++ Monte Carlo Event Record for High Energy Physics

CERN Document Server

Dobbs, M

2000-01-01

HepMC is an Object Oriented event record written in C++ for High Energy Physics Monte Carlo Event Generators. Many extensions from HEPEVT, the Fortran HEP standard, are supported: the number of entries is unlimited, spin density matrices can be stored with each vertex, flow patterns (such as colour) can be stored and traced, random number generator states can be stored, and an arbitrary number of event weights can be included. Particles and vertices are stored separately in a graph structure, reflecting the evolution of a physics event. The added information supports the modularisation of event generators. The event record has been kept as simple as possible with minimal internal/external dependencies. Event information is accessed by means of iterators supplied with HepMC.

Construction of a high-density genetic map for grape using next generation restriction-site associated DNA sequencing

Directory of Open Access Journals (Sweden)

Wang Nian

2012-08-01

Full Text Available Abstract Background Genetic mapping and QTL detection are powerful methodologies in plant improvement and breeding. Construction of a high-density and high-quality genetic map would be of great benefit in the production of superior grapes to meet human demand. High throughput and low cost of the recently developed next generation sequencing (NGS technology have resulted in its wide application in genome research. Sequencing restriction-site associated DNA (RAD might be an efficient strategy to simplify genotyping. Combining NGS with RAD has proven to be powerful for single nucleotide polymorphism (SNP marker development. Results An F1 population of 100 individual plants was developed. In-silico digestion-site prediction was used to select an appropriate restriction enzyme for construction of a RAD sequencing library. Next generation RAD sequencing was applied to genotype the F1 population and its parents. Applying a cluster strategy for SNP modulation, a total of 1,814 high-quality SNP markers were developed: 1,121 of these were mapped to the female genetic map, 759 to the male map, and 1,646 to the integrated map. A comparison of the genetic maps to the published Vitis vinifera genome revealed both conservation and variations. Conclusions The applicability of next generation RAD sequencing for genotyping a grape F1 population was demonstrated, leading to the successful development of a genetic map with high density and quality using our designed SNP markers. Detailed analysis revealed that this newly developed genetic map can be used for a variety of genome investigations, such as QTL detection, sequence assembly and genome comparison.

Effect of Magnetic Flux Density and Applied Current on Temperature, Velocity and Entropy Generation Distributions in MHD Pumps

Directory of Open Access Journals (Sweden)

M. Kiyasatfar

2011-01-01

Full Text Available In the present study, simulation of steady state, incompressible and fully developed laminar flow has been conducted in a magneto hydrodynamic (MHD pump. The governing equations are solved numerically by finite-difference method. The effect of the magnetic flux density and current on the flow and temperature distributions in a MHD pump is investigated. The obtained results showed that controlling the flow and the temperature is possible through the controlling of the applied current and the magnetic flux. Furthermore, the effects of the magnetic flux density and current on entropy generation in MHD pump are considered. Our presented numerical results are in good agreement with the experimental data showed in literature.

Four generations and Higgs physics

Energy Technology Data Exchange (ETDEWEB)

Kribs, Graham D. [Department of Physics and Institute of Theoretical Science, University of Oregon, Eugene (United States); Plehn, Tilman [SUPA, School of Physics, University of Edinburgh (United Kingdom); Spannowsky, Michael [Institut fuer Theoretische Physik, Universitaet Karlsruhe (Germany); Tait, Tim M.P. [HEP Division, Argonne National Laboratory (United States)

2008-07-01

A fourth generation has been considered and forgotten or discarded several times, wrongly leaving the impression that it is either ruled out or disfavored by experimental data. We revisit a fourth generation of chiral matter in the light of present electroweak precision data and deduce effects on Higgs phenomenology. We find a chiral fourth generation to be a viable model which can yield interesting signatures at the LHC, e.g. production rates are enhanced, weak-boson-fusion channels are suppressed, angular distributions are modified and Higgs pairs can be observed.

Mathematical Modeling and Evaluation of Human Motions in Physical Therapy Using Mixture Density Neural Networks.

Science.gov (United States)

Vakanski, A; Ferguson, J M; Lee, S

2016-12-01

The objective of the proposed research is to develop a methodology for modeling and evaluation of human motions, which will potentially benefit patients undertaking a physical rehabilitation therapy (e.g., following a stroke or due to other medical conditions). The ultimate aim is to allow patients to perform home-based rehabilitation exercises using a sensory system for capturing the motions, where an algorithm will retrieve the trajectories of a patient's exercises, will perform data analysis by comparing the performed motions to a reference model of prescribed motions, and will send the analysis results to the patient's physician with recommendations for improvement. The modeling approach employs an artificial neural network, consisting of layers of recurrent neuron units and layers of neuron units for estimating a mixture density function over the spatio-temporal dependencies within the human motion sequences. Input data are sequences of motions related to a prescribed exercise by a physiotherapist to a patient, and recorded with a motion capture system. An autoencoder subnet is employed for reducing the dimensionality of captured sequences of human motions, complemented with a mixture density subnet for probabilistic modeling of the motion data using a mixture of Gaussian distributions. The proposed neural network architecture produced a model for sets of human motions represented with a mixture of Gaussian density functions. The mean log-likelihood of observed sequences was employed as a performance metric in evaluating the consistency of a subject's performance relative to the reference dataset of motions. A publically available dataset of human motions captured with Microsoft Kinect was used for validation of the proposed method. The article presents a novel approach for modeling and evaluation of human motions with a potential application in home-based physical therapy and rehabilitation. The described approach employs the recent progress in the field of

Why Density Dependent Propulsion?

Science.gov (United States)

Robertson, Glen A.

2011-01-01

In 2004 Khoury and Weltman produced a density dependent cosmology theory they call the Chameleon, as at its nature, it is hidden within known physics. The Chameleon theory has implications to dark matter/energy with universe acceleration properties, which implies a new force mechanism with ties to the far and local density environment. In this paper, the Chameleon Density Model is discussed in terms of propulsion toward new propellant-less engineering methods.

Peripheral bone mineral density and different intensities of physical activity in children 6-8 years old: the Copenhagen School Child Intervention study

DEFF Research Database (Denmark)

Hasselstrøm, H; Karlsson, K M; Hansen, S E

2007-01-01

-stimulating physical activity, we evaluated different definitions of vigorous physical activity. The boys had 3.2% higher distal forearm bone mineral content (BMC, P girls. They also carried out 9.7% more daily physical activity and spent 14.6-19.0% more...... time in vigorous physical activity (all P girls. In contrast, the girls had 3.8% higher calcaneal BMC (P boys. Both calcaneal and forearm BMD were significantly related to total time of daily physical activity as well......This study aimed to evaluate the association between objectively measured habitual physical activity and calcaneal and forearm bone mineral density (BMD, g/cm(2)), one mechanically more loaded and one less loaded skeletal region, in children aged 6-8 years. BMD was measured in 297 boys and 265...

A computer program for estimating the power-density spectrum of advanced continuous simulation language generated time histories

Science.gov (United States)

Dunn, H. J.

1981-01-01

A computer program for performing frequency analysis of time history data is presented. The program uses circular convolution and the fast Fourier transform to calculate power density spectrum (PDS) of time history data. The program interfaces with the advanced continuous simulation language (ACSL) so that a frequency analysis may be performed on ACSL generated simulation variables. An example of the calculation of the PDS of a Van de Pol oscillator is presented.

Test data on electrical contacts at high surface velocities and high current densities for homopolar generators

International Nuclear Information System (INIS)

Brennan, M.; Tolk, K.M.; Weldon, W.F.; Rylander, H.G.; Woodson, H.H.

1977-01-01

Test data is presented for one grade of copper graphite brush material, Morganite CMlS, over a wide range of surface velocities, atmospheres, and current densities that are expected for fast discharge (<100 ms) homopolar generators. The brushes were run on a copper coated 7075-T6 aluminum disk at surface speeds up to 277 m/sec. One electroplated copper and three flame sprayed copper coatings were used during the tests. Significant differences in contact voltage drops and surface mechanical properties of the copper coatings were observed

Current density tensors

Science.gov (United States)

Lazzeretti, Paolo

2018-04-01

It is shown that nonsymmetric second-rank current density tensors, related to the current densities induced by magnetic fields and nuclear magnetic dipole moments, are fundamental properties of a molecule. Together with magnetizability, nuclear magnetic shielding, and nuclear spin-spin coupling, they completely characterize its response to magnetic perturbations. Gauge invariance, resolution into isotropic, deviatoric, and antisymmetric parts, and contributions of current density tensors to magnetic properties are discussed. The components of the second-rank tensor properties are rationalized via relationships explicitly connecting them to the direction of the induced current density vectors and to the components of the current density tensors. The contribution of the deviatoric part to the average value of magnetizability, nuclear shielding, and nuclear spin-spin coupling, uniquely determined by the antisymmetric part of current density tensors, vanishes identically. The physical meaning of isotropic and anisotropic invariants of current density tensors has been investigated, and the connection between anisotropy magnitude and electron delocalization has been discussed.

Enhanced THz radiation generation by photo-mixing of tophat lasers in rippled density plasma with a planar magnetostatic wiggler and s-parameter

Science.gov (United States)

Abedi-Varaki, M.

2018-02-01

In this paper, the effects of planar magnetostatic wiggler and s-parameter on the terahertz (THz) radiation generation through rippled plasma have been investigated. Efficient THz radiation generation by photo-mixing of tophat lasers for rippled density plasma in the presence of the wiggler field has been presented. Fundamental equations for the analysis of the non-linear current density and THz radiation generation by wiggler magnetostatic field have been derived. It is shown that for the higher order of the tophat lasers, the values of THz amplitude are greater. In fact, the higher order of the tophat lasers has a sharp gradient in the intensity of lasers, which leads to a stronger nonlinear ponderomotive force and, consequently, a stronger current density. In addition, it is seen that by increasing s-parameter, the normalized transverse profile becomes more focused near the axis of y. Furthermore, it is observed that the normalized laser efficiency has a decreasing trend with increasing normalized THz frequency for different values of the wiggler field. Also, it is shown that by employing a greater order of the tophat lasers and a stronger wiggler field, the efficiency of order of 30% can be achieved. Moreover, it is found that we can control focus and intensity of THz radiation emitted in rippled plasma by choosing the appropriate order of the tophat lasers and tuning of the wiggler field.

Enhancement of in vitro high-density polyethylene (HDPE) degradation by physical, chemical, and biological treatments.

Science.gov (United States)

Balasubramanian, V; Natarajan, K; Rajeshkannan, V; Perumal, P

2014-11-01

Partially degraded high-density polyethylene (HDPE) was collected from plastic waste dump yard for biodegradation using fungi. Of various fungi screened, strain MF12 was found efficient in degrading HDPE by weight loss and Fourier transform infrared (FT-IR) spectrophotometric analysis. Strain MF12 was selected as efficient HDPE degraders for further studies, and their growth medium composition was optimized. Among those different media used, basal minimal medium (BMM) was suitable for the HDPE degradation by strain MF12. Strain MF12 was subjected to 28S rRNA sequence analysis and identified as Aspergillus terreus MF12. HDPE degradation was carried out using combinatorial physical and chemical treatments in conjunction to biological treatment. The high level of HDPE degradation was observed in ultraviolet (UV) and KMnO4/HCl with A. terreus MF12 treatment, i.e., FT10. The abiotic physical and chemical factors enhance the biodegradation of HDPE using A. terreus MF12.

Study on the impact of the engineering energy gain and the FPC mass power density on the generation cost of fusion power plant

International Nuclear Information System (INIS)

Huang Desuo; Wu Yican

2004-01-01

The impact of the engineering energy gain and the fusion-power-core (FPC) mass power density (MPD) on the generation cost of fusion power plant are analyzed based on the economic elasticity approach in this paper. From the functions describing the relationship of the generation cost with the engineering energy gain and the MPD, the elasticity coefficients of the generation cost with the engineering energy gain and the MPD have been derived respectively to analyze their sensitivity to the generation cost and the MPD to the generation cost decreases with increasing the engineering energy gain or the MPD. (authors)

Physics of laser plasma

International Nuclear Information System (INIS)

Rubenchik, A.; Witkowski, S.

1991-01-01

This book provides a comprehensive review of laser fusion plasma physics and contains the most up-to-date information on high density plasma physics and radiation transport, useful for astrophysicists and high density physicists

Energy sprawl, land taking and distributed generation: towards a multi-layered density

International Nuclear Information System (INIS)

Moroni, Stefano; Antoniucci, Valentina; Bisello, Adriano

2016-01-01

The transition from fossil fuels to renewable resources is highly desirable to reduce air pollution, and improve energy efficiency and security. Many observers are concerned, however, that the diffusion of systems based on renewable resources may give rise to energy sprawl, i.e. an increasing occupation of available land to build new energy facilities of this kind. These critics foresee a transition from the traditional fossil-fuel systems, towards a renewable resource system likewise based on large power stations and extensive energy grids. A different approach can be taken to reduce the risk of energy sprawl, and this will happen if the focus is as much on renewable sources as on the introduction of distributed renewable energy systems based on micro plants (photovoltaic panels on the roofs of buildings, micro wind turbines, etc.) and on multiple micro-grids. Policy makers could foster local energy enterprises by: introducing new enabling rules; making more room for contractual communities; simplifying the compliance process; proposing monetary incentives and tax cuts. We conclude that the diffusion of innovation in this field will lead not to an energy sprawl but to a new energy system characterized by a multi-layered density: a combination of technology, organization, and physical development. - Highlights: • Energy sprawl is not a necessary consequence of the transition to renewable sources. • A polycentric, distributed renewable energy system reduces land consumption. • This polycentric model is founded on building-related renewable energy production and micro-grids. • Enabling rules, simplified compliance, and tax cuts can foster this result. • The concept of multi-layered density is proposed as a new framework for interpreting this scenario.

The Physical Basis of Lg Generation by Explosion Sources

Energy Technology Data Exchange (ETDEWEB)

J. L. Stevens; G. E. Baker; H. Xu; T. J. Bennett; N. Rimer; S. D. Day

2004-12-20

The goal of this project has been to develop a quantitative predictive capability for explosion-generated Lg phases with a sound and unambiguous physical basis. The research program consisted of a theoretical investigation of explosion-generated Lg combined with an observational study. The specific question addressed by this research program is how the Lg phase is generated by underground nuclear explosions. This question is fundamental to how Lg phases are interpreted for use in explosion yield estimation and earthquake/explosion discrimination. To constrain modeling, we have extensively reviewed the existing literature and complemented that work with an examination of several explosion data sets, most notably: (1) Degelen Mountain explosions recorded between 7 and 57 km, with corresponding recordings at Borovoye, at approximately 650 km; (2) recordings from Russian deep seismic sounding experiments; (3) NTS explosion sources including the NPE and nuclear tests covering a range of source depths and media properties. A simple point explosion in an infinite medium generates no shear waves, so the Lg phase is generated entirely by non-spherical components of the source and conversions through reflections and scattering. We find that the most important contributors to the Lg phase are: (1) P to S conversion at the free surface and other near source interfaces, (2) S waves generated directly by a realistically distributed explosion source including nonlinear effects due to the free surface and gravity, and (3) Rg scattering to Lg. Additional effects that contribute significantly to Lg are scattering of converted S phases that traps more of the converted P-to-S in the crust, and randomization of the components of Lg. The pS phase from a spherically symmetric explosion source in media with P-wave velocity less than upper mantle S-wave velocity is trapped in the crust and can explain the observed radial and vertical Lg. The free surface pS converted phase from the same

Finite quantum physics and noncommutative geometry

International Nuclear Information System (INIS)

Balachandran, A.P.; Ercolessi, E.; Landi, G.; Teotonio-Sobrinho, P.; Lizzi, F.; Sparano, G.

1994-04-01

Conventional discrete approximations of a manifold do not preserve its nontrivial topological features. In this article we describe an approximation scheme due to Sorkin which reproduces physically important aspects of manifold topology with striking fidelity. The approximating topological spaces in this scheme are partially ordered sets (posets). Now, in ordinary quantum physics on a manifold M, continuous probability densities generate the commutative C * -algebra C(M) of continuous functions on M. It has a fundamental physical significance, containing the information to reconstruct the topology of M, and serving to specify the domains of observables like the Hamiltonian. For a poset, the role of this algebra is assumed by a noncommutative C * -algebra A. As noncommutative geometries are based on noncommutative C * -algebra, we therefore have a remarkable connection between finite approximations to quantum physics and noncommutative geometries. Varies methods for doing quantum physics using A are explored. Particular attention is paid to developing numerically viable approximation schemes which at the same time preserve important topological features of continuum physics. (author). 21 refs, 13 figs

First-generation physical map of the Culicoides variipennis (Diptera: Ceratopogonidae) genome.

Science.gov (United States)

Nunamaker, R A; Brown, S E; McHolland, L E; Tabachnick, W J; Knudson, D L

1999-11-01

Recombinant cosmids labeled with biotin-11-dUTP or digoxigenin by nick translation were used as in situ hybridization probes to metaphase chromosomes of Culicoides variipennis (Coquillett). Paired fluorescent signals were detected on each arm of sister chromatids and were ordered along the 3 chromosomes. Thirty-three unique probes were mapped to the 3 chromosomes of C. variipennis (2n = 6): 7 to chromosome 1, 20 to chromosome 2, and 6 to chromosome 3. This work represents the first stage in generating a physical map of the genome of C. variipennis.

Transition densities with electron scattering

International Nuclear Information System (INIS)

Heisenberg, J.

1985-01-01

This paper reviews the ground state and transition charge densities in nuclei via electron scattering. Using electrons as a spectroscopic tool in nuclear physics, these transition densities can be determined with high precision, also in the nuclear interior. These densities generally ask for a microscopic interpretation in terms of contributions from individual nucleons. The results for single particle transitions confirm the picture of particle-phonon coupling. (Auth.)

Beam diagnostics for Laser-induced proton generation at KAERI

International Nuclear Information System (INIS)

Kim, Dong Heun; Park, Seong Hee; Jeong, Young Uk; Lee, Ki Tae; Chan, Young Ho; Lee, Byung Cheol; Yoo, Byeong Duk

2005-01-01

With an advent of femto-second lasers, a laseraccelerated ion generation has been world-widely studied for medical and nuclear applications. It is known that protons with the energy from several tens MeV to a few hundreds MeV require for a cancer therapy and nuclear reaction. Even though, up to present, the maximum energy of laser-accelerated proton is about 60 MeV, it is expected that the energy of protons generated can be obtained at least up to 150 MeV. According to theoretical and experimental works, it turns out the energy distribution and the flux of ions strongly depends on the intensity of a fs laser at a target. However, physics on laser-plasma interaction is still not clear. The precise measurements of parameters of a fs laser and ions are important to figure out the physics and develop the theoretical interpretation. Typically, beam diagnostic system includes measurements and/or monitoring of the temporal and spatial profiles of lasers at the target as well as the energy spectrum and density profile of protons, which are critical for the analysis of mechanism and the characterization of protons generated. We fabricated and installed the target chamber for laser-accelerated proton generation and are now integrating beam diagnostic system. For laser diagnostics, beam monitoring and alignment system has been installed. For a charged particle, CR-39 detectors, Thomson parabola spectrometer, and Si charged particle detectors are installed for density profile and energy spectrum. In this paper, we discuss the laser beam monitoring and alignment system. We also estimates expected spectrum of protons from Thomson parabola spectrometer, depending on the parameters of protons

Computer soundcard as an AC signal generator and oscilloscope for the physics laboratory

Science.gov (United States)

Sinlapanuntakul, Jinda; Kijamnajsuk, Puchong; Jetjamnong, Chanthawut; Chotikaprakhan, Sutharat

2018-01-01

The purpose of this paper is to develop both an AC signal generator and a dual-channel oscilloscope based on standard personal computer equipped with sound card as parts of the laboratory of the fundamental physics and the introduction to electronics classes. The setup turns the computer into the two channel measured device which can provides sample rate, simultaneous sampling, frequency range, filters and others essential capabilities required to perform amplitude, phase and frequency measurements of AC signal. The AC signal also generate from the same computer sound card output simultaneously in any waveform such as sine, square, triangle, saw-toothed pulsed, swept sine and white noise etc. These can convert an inexpensive PC sound card into powerful device, which allows the students to measure physical phenomena with their own PCs either at home or at university attendance. A graphic user interface software was developed for control and analysis, including facilities for data recording, signal processing and real time measurement display. The result is expanded utility of self-learning for the students in the field of electronics both AC and DC circuits, including the sound and vibration experiments.

Generating and using truly random quantum states in Mathematica

Science.gov (United States)

Miszczak, Jarosław Adam

2012-01-01

The problem of generating random quantum states is of a great interest from the quantum information theory point of view. In this paper we present a package for Mathematica computing system harnessing a specific piece of hardware, namely Quantis quantum random number generator (QRNG), for investigating statistical properties of quantum states. The described package implements a number of functions for generating random states, which use Quantis QRNG as a source of randomness. It also provides procedures which can be used in simulations not related directly to quantum information processing. Program summaryProgram title: TRQS Catalogue identifier: AEKA_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKA_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 7924 No. of bytes in distributed program, including test data, etc.: 88 651 Distribution format: tar.gz Programming language: Mathematica, C Computer: Requires a Quantis quantum random number generator (QRNG, http://www.idquantique.com/true-random-number-generator/products-overview.html) and supporting a recent version of Mathematica Operating system: Any platform supporting Mathematica; tested with GNU/Linux (32 and 64 bit) RAM: Case dependent Classification: 4.15 Nature of problem: Generation of random density matrices. Solution method: Use of a physical quantum random number generator. Running time: Generating 100 random numbers takes about 1 second, generating 1000 random density matrices takes more than a minute.

Outline of the relativistic electron beam (REB) generator at Institute of Plasma Physics, Nagoya University

International Nuclear Information System (INIS)

Tsuzuki, Tetsuya

1979-01-01

The REB generators at the Institute of Plasma Physics are introduced. The generators Phoebus-2 and Phoebus-3 are main generators. The generators consist of a Marx generator (a condenser bank), a pulse forming line (PFL), a transmission line (TL) and a diode part. The rise time of current in the Marx generator must be short. The charge up time of the Phoebus-2 and the Phoebus-3 is less than 400 ns. The jitter is less than 10 ns. The dielectric material of the PFL is water, since the dielectric constant is large, and it makes self recovering. The inductance of gap at the edge of PFL should be small. The gap is useful for short rise time. The TL prevents the prepulse at the time of charging-up and works as an impedance transformer. The Phoebus-3 is connected to the torus system (SPAC-6) to make experiment on REB ring formation. (Kato, T.)

Density-functional theory for internal magnetic fields

Science.gov (United States)

Tellgren, Erik I.

2018-01-01

A density-functional theory is developed based on the Maxwell-Schrödinger equation with an internal magnetic field in addition to the external electromagnetic potentials. The basic variables of this theory are the electron density and the total magnetic field, which can equivalently be represented as a physical current density. Hence, the theory can be regarded as a physical current density-functional theory and an alternative to the paramagnetic current density-functional theory due to Vignale and Rasolt. The energy functional has strong enough convexity properties to allow a formulation that generalizes Lieb's convex analysis formulation of standard density-functional theory. Several variational principles as well as a Hohenberg-Kohn-like mapping between potentials and ground-state densities follow from the underlying convex structure. Moreover, the energy functional can be regarded as the result of a standard approximation technique (Moreau-Yosida regularization) applied to the conventional Schrödinger ground-state energy, which imposes limits on the maximum curvature of the energy (with respect to the magnetic field) and enables construction of a (Fréchet) differentiable universal density functional.

Physical data generation methodology for return-to-power steam line break analysis

Energy Technology Data Exchange (ETDEWEB)

Zee, Sung Kyun; Lee, Chung Chan; Lee, Chang Kue [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1996-02-01

Current methodology to generate physics data for steamline break accident analysis of CE-type nuclear plant such as Yonggwang Unit 3 is valid only if the core reactivity does not reach the criticality after shutdown. Therefore, the methodology requires tremendous amount of net scram worth, specially at the end of the cycle when moderator temperature coefficient is most negative. Therefore, we need a new methodology to obtain reasonably conservation physics data, when the reactor returns to power condition. Current methodology used ROCS which include only closed channel model. But it is well known that the closed channel model estimates the core reactivity too much negative if core flow rate is low. Therefore, a conservative methodology is presented which utilizes open channel 3D HERMITE model. Current methodology uses ROCS which include only closed channel model. But it is well known that the closed channel model estimates the core reactivity too much negative if core flow rate is low. Therefore, a conservative methodology is presented which utilizes open channel 3D HERMITE model. Return-to-power reactivity credit is produced to assist the reactivity table generated by closed channel model. Other data includes hot channel axial power shape, peaking factor and maximum quality for DNBR analysis. It also includes pin census for radiological consequence analysis. 48 figs., 22 tabs., 18 refs. (Author) .new.

Effect of heterogeneous distribution of crosslink density on physical properties of radiation vulcanized NR (Natural Rubber) latex film

International Nuclear Information System (INIS)

Keizo Makuuchi; Fumio Yoshii; Miura, H.; Murakami, K.

1996-01-01

Thus a study has been carried out to investigate the effect of particle to particle variation in crosslink density on physical properties of radiation vulcanized NR latex film. NR latex was irradiated in small bottle by γ rays without vulcanization accelerator to provide latex rubber particles having homogeneous distribution of crosslink density. The doses were 30, 50, 100, 250, 300, 400, 500 and 600 kGy. Weight swelling ratio, gel fraction, tensile strength and elongation at break of the latex film from the mixed latex were measured. The vulcanization dose of this latex was 250 kGy. Then the two different latexes were mixed in a such way to adjust the average dose of 250 kGy to prepare a latex consisting of rubber particles having heterogeneous distribution of crosslink density. Tensile strength of the latex film was depressed by mixing. The reduction increased with increasing the decrease of gel fraction by mixing. However the reduction was not serious when the dose difference of two latexes was less than 200 kGy

Generating Physics Content for the Designers.

Science.gov (United States)

Bishop, Mary Jean; Bross, Thomas R.; Nelson, James H.

2001-01-01

Each designer contributing to this special issue was asked to prepare an introductory lesson on the physics of motion aimed at eighth to eleventh graders. This article presents a brief description of how a detailed physics content was researched, edited, and refined by subject-matter experts, and then ultimately presented to the instructional…

Dynamic Statistical Models for Pyroclastic Density Current Generation at Soufrière Hills Volcano

Science.gov (United States)

Wolpert, Robert L.; Spiller, Elaine T.; Calder, Eliza S.

2018-05-01

To mitigate volcanic hazards from pyroclastic density currents, volcanologists generate hazard maps that provide long-term forecasts of areas of potential impact. Several recent efforts in the field develop new statistical methods for application of flow models to generate fully probabilistic hazard maps that both account for, and quantify, uncertainty. However a limitation to the use of most statistical hazard models, and a key source of uncertainty within them, is the time-averaged nature of the datasets by which the volcanic activity is statistically characterized. Where the level, or directionality, of volcanic activity frequently changes, e.g. during protracted eruptive episodes, or at volcanoes that are classified as persistently active, it is not appropriate to make short term forecasts based on longer time-averaged metrics of the activity. Thus, here we build, fit and explore dynamic statistical models for the generation of pyroclastic density current from Soufrière Hills Volcano (SHV) on Montserrat including their respective collapse direction and flow volumes based on 1996-2008 flow datasets. The development of this approach allows for short-term behavioral changes to be taken into account in probabilistic volcanic hazard assessments. We show that collapses from the SHV lava dome follow a clear pattern, and that a series of smaller flows in a given direction often culminate in a larger collapse and thereafter directionality of the flows change. Such models enable short term forecasting (weeks to months) that can reflect evolving conditions such as dome and crater morphology changes and non-stationary eruptive behavior such as extrusion rate variations. For example, the probability of inundation of the Belham Valley in the first 180 days of a forecast period is about twice as high for lava domes facing Northwest toward that valley as it is for domes pointing East toward the Tar River Valley. As rich multi-parametric volcano monitoring dataset become

'Anomalous electron transport' with 'Giant Current Density' at room temperature observed with nanogranular materials

International Nuclear Information System (INIS)

Koops, Hans W.P.

2013-01-01

Focused electron beam induced deposition is a novel bottom up nano-structurization technology. An electron beam of high power density is used to generate nano- structures with dimensions > 20 nm, but being composed from amorphous or nanogranular materials with crystals of 2 to 5 nm diameter embedded in a Fullerene matrix. Those compounds are generated in general by secondary or low energy electrons in layers of inorganic, organic, organometallic compounds absorbed to the sample. Those are converted into nanogranular materials by the electron beam following chemical and physical laws, as given by 'Mother Nature'. Metals and amorphous mixtures of chemical compounds from metals are normal resistors, which can carry a current density J 2 . Nanogranular composites like Au/C or Pt/C with metal nanocrystals embedded in a Fullerene matrix have hopping conduction with 0-dimensional Eigen-value characteristics and show 'anomalous electron transport' and can carry 'Giant Current Densities' with values from > 1 MA/cm 2 to 0.1 GA/cm 2 without destruction of the materials. However the area connecting the nanogranular material with a metal with a 3-dimensional electron gas needs to be designed, that the flowing current is reduced to the current density values which the 3-D metal can support without segregation. The basis for a theoretical explanation of the phenomenon can be geometry quantization for Coulomb blockade, of electron surface orbitals around the nanocrystals, hopping conduction, and the limitation of the density of states for phonons in geometry confined non percolated granular materials with strong difference in mass and orientation. Several applications in electronics, signal generators, light sources, detectors, and solar energy harvesting are suggested. (author)

Genarris: Random generation of molecular crystal structures and fast screening with a Harris approximation

Science.gov (United States)

Li, Xiayue; Curtis, Farren S.; Rose, Timothy; Schober, Christoph; Vazquez-Mayagoitia, Alvaro; Reuter, Karsten; Oberhofer, Harald; Marom, Noa

2018-06-01

We present Genarris, a Python package that performs configuration space screening for molecular crystals of rigid molecules by random sampling with physical constraints. For fast energy evaluations, Genarris employs a Harris approximation, whereby the total density of a molecular crystal is constructed via superposition of single molecule densities. Dispersion-inclusive density functional theory is then used for the Harris density without performing a self-consistency cycle. Genarris uses machine learning for clustering, based on a relative coordinate descriptor developed specifically for molecular crystals, which is shown to be robust in identifying packing motif similarity. In addition to random structure generation, Genarris offers three workflows based on different sequences of successive clustering and selection steps: the "Rigorous" workflow is an exhaustive exploration of the potential energy landscape, the "Energy" workflow produces a set of low energy structures, and the "Diverse" workflow produces a maximally diverse set of structures. The latter is recommended for generating initial populations for genetic algorithms. Here, the implementation of Genarris is reported and its application is demonstrated for three test cases.

Open-system Kohn-Sham density functional theory.

Science.gov (United States)

Zhou, Yongxi; Ernzerhof, Matthias

2012-03-07

A simple model for electron transport through molecules is provided by the source-sink potential (SSP) method [F. Goyer, M. Ernzerhof, and M. Zhuang, J. Chem. Phys. 126, 144104 (2007)]. In SSP, the boundary conditions of having an incoming and outgoing electron current are enforced through complex potentials that are added to the Hamiltonian. Depending on the sign of the imaginary part of the potentials, current density is generated or absorbed. In this way, a finite system can be used to model infinite molecular electronic devices. The SSP has originally been developed for the Hückel method and subsequently it has been extended [F. Goyer and M. Ernzerhof, J. Chem. Phys. 134, 174101 (2011)] to the Hubbard model. Here we present a step towards its generalization for first-principles electronic structure theory methods. In particular, drawing on our earlier work, we discuss a new generalized density functional theory for complex non-Hermitian Hamiltonians. This theory enables us to combine SSP and Kohn-Sham theory to obtain a method for the description of open systems that exchange current density with their environment. Similarly, the Hartree-Fock method is extended to the realm of non-Hermitian, SSP containing Hamiltonians. As a proof of principle, we present the first applications of complex-density functional theory (CODFT) as well as non-Hermitian Hartree-Fock theory to electron transport through molecules. © 2012 American Institute of Physics

On the physical factors influencing on the bone mineral density of the elderly

International Nuclear Information System (INIS)

Katoh, Yoh; Abe, Shinji; Ogura, Izumi; Ishiguchi, Kohji; Matsui, Yohko; Moriki, Hisakazu; Suzuki, Takao.

1992-01-01

Individual characteristics such as sex, age, height and weight have been considered as the factors influencing bone mineral density (BMD). The purpose of this study is to analyze the relation between these factors and the data of BMD obtained from 387 healthy old persons (176 males and 211 females) at the age of 65 and over who are living in an urban community in a western suburb of Tokyo and chosen by randomized sampling. BMD of the third lumbar spine from lateral projection using dual energy X-ray absorptiometry (DEXA) in the van was measured during a general health survey which included other physical examinations such as weight, height, blood pressure and so on. BMD obtained was analyzed in relation to these variables using both simple and multiple regression analyses. Standard regression coefficients showed that all physical variables had a significant relationship to BMD except the height in males. Standard regression coefficients of height and age for the males were the same, but height was evaluated to have slight influence on BMD by statistically. In a multiple regression analysis, the multiple correlation coefficient was somewhat lower in both sexes (males: R=0.448; females: R=0.381) than expected. Our analyses of these factors showed that there might be other possible factors influencing BMD regarding the elderly with the exception of age, sex, height and weight. (author)

The physics of W transport illuminated by recent progress in W density diagnostics at ASDEX Upgrade

Science.gov (United States)

Odstrcil, T.; Pütterich, T.; Angioni, C.; Bilato, R.; Gude, A.; Odstrcil, M.; ASDEX Upgrade Team; the EUROfusion MST1 Team

2018-01-01

Due to the high mass and charge of the heavy ions, centrifugal and electrostatic forces cause a significant variation in their poloidal density. The impact of these forces on the poloidal density profile of tungsten was investigated utilizing the detailed two-dimensional SXR emissivity profiles from the ASDEX Upgrade tokamak. The perturbation in the electrostatic potential generated by magnetic trapping of the non-thermal ions from neutral beam injection was found to be responsible for significant changes in the poloidal distribution of tungsten ions. An excellent match with the results from fast particle modeling was obtained, validating the model for the poloidal fast particle distribution. Additionally, an enhancement of the neoclassical transport due to an outboard side impurity localization was measured in the experiment when analyzing the tungsten flux between sawtooth crashes. A qualitative match with neoclassical modeling was found, demonstrating the possibility of minimizing neoclassical transport by an optimization of the poloidal asymmetry profile of the impurity.

Derivation of the threshold condition for the ion temperature gradient mode with an inverted density profile from a simple physics picture

Science.gov (United States)

Jhang, Hogun

2018-05-01

We show that the threshold condition for the toroidal ion temperature gradient (ITG) mode with an inverted density profile can be derived from a simple physics argument. The key in this picture is that the density inversion reduces the ion compression due to the ITG mode and the electron drift motion mitigates the poloidal potential build-up. This condition reproduces the same result that has been reported from a linear gyrokinetic calculation [T. S. Hahm and W. M. Tang, Phys. Fluids B 1, 1185 (1989)]. The destabilizing role of trapped electrons in toroidal geometry is easily captured in this picture.

The School Physical Education class as a generator of Physical-Sportive Leisure

Directory of Open Access Journals (Sweden)

Sanz Arazuri, Eva

2012-07-01

Full Text Available this article tries to know the relationships that can be found between School Physical Education and Leisure Physical Sportive Practice among the population of teenagers and young people from Huesca who study Compulsory Secondary Education, Bachillerato, Professional Studies, taking into account the gender. In this research, the satisfaction level referred to the experienced physical education lessons is expressed through the level of benefit that is assigned to those experiences when young people start extracurricular physical-sportive practice. Among the main conclusions, it is checked that poorly one out three of students from Huesca, states that physical education lessons were useful to access extracurricular practice. As well, the consideration that physical education lessons are a way to access to extracurricular physical-sportive practice is mainly associated to women. The more useful are the lived experiences during P.E. lessons, the more is the number of feminine students who go on practicing and less is the number of people that give up sport. In fact, seven out of ten of feminine students who refer to these lessons as very useful, keep on practicing and three of them abandon physical activity. This relationship is not established taking about masculine genre.

Study of physical properties, gas generation and gas retention in simulated Hanford waste

International Nuclear Information System (INIS)

Bryan, S.A.; Pederson, L.R.; Scheele, R.D.

1993-04-01

The purpose of this study was to establish the chemical and physical processes responsible for the generation and retention of gases within high-level waste from Tank 101-SY on the Hanford Site. This research, conducted using simulated waste on a laboratory scale, supports the development of mitigation/remediation strategies for Tank 101-SY. Simulated waste formulations are based on actual waste compositions. Selected physical properties of the simulated waste are compared to properties of actual Tank 101-SY waste samples. Laboratory studies using aged simulated waste show that significant gas generation occurs thermally at current tank temperatures (∼60 degrees C). Gas compositions include the same gases produced in actual tank waste, primarily N 2 , N 2 O, and H 2 . Gas stoichiometries have been shown to be greatly influenced by several organic and inorganic constituents within the simulated waste. Retention of gases in the simulated waste is in the form of bubble attachment to solid particles. This attachment phenomenon is related to the presence of organic constituents (HEDTA, EDTA, and citrate) of the simulated waste. A mechanism is discussed that relates the gas bubble/particle interactions to the partially hydrophobic surface produced on the solids by the organic constituents

The physical basis of bacterial quorum communication

CERN Document Server

2015-01-01

This book aims to educate physical scientists and quantitatively-oriented biologists on the application of physical experimentation and analysis, together with appropriate modeling, to understanding and interpreting microbial chemical communication and especially quorum sensing (QS). Quorum sensing describes a chemical communication behavior that is nearly universal among bacteria. Individual cells release a diffusible small molecule (an autoinducer) into their environment. A high concentration of this autoinducer serves as a signal of high population density, triggering new patterns of gene expression throughout the population. However QS is often much more complex than simple census-taking. Many QS bacteria produce and detect multiple autoinducers, which generate quorum signal cross talk with each other and with other bacterial species. QS gene regulatory networks operate in physically complex environments and respond to a range of inputs in addition to autoinducer signals. While many individual QS systems ...

Density-wave oscillations

International Nuclear Information System (INIS)

Belblidia, L.A.; Bratianu, C.

1979-01-01

Boiling flow in a steam generator, a water-cooled reactor, and other multiphase processes can be subject to instabilities. It appears that the most predominant instabilities are the so-called density-wave oscillations. They can cause difficulties for three main reasons; they may induce burnout; they may cause mechanical vibrations of components; and they create system control problems. A comprehensive review is presented of experimental and theoretical studies concerning density-wave oscillations. (author)

Relativistic density functional for nuclear structure

CERN Document Server

2016-01-01

This book aims to provide a detailed introduction to the state-of-the-art covariant density functional theory, which follows the Lorentz invariance from the very beginning and is able to describe nuclear many-body quantum systems microscopically and self-consistently. Covariant density functional theory was introduced in nuclear physics in the 1970s and has since been developed and used to describe the diversity of nuclear properties and phenomena with great success. In order to provide an advanced and updated textbook of covariant density functional theory for graduate students and nuclear physics researchers, this book summarizes the enormous amount of material that has accumulated in the field of covariant density functional theory over the last few decades as well as the latest developments in this area. Moreover, the book contains enough details for readers to follow the formalism and theoretical results, and provides exhaustive references to explore the research literature.

Apparatus and method for generating high density pulses of electrons

International Nuclear Information System (INIS)

Lee, C.; Oettinger, P.E.

1981-01-01

An apparatus and method are described for the production of high density pulses of electrons using a laser energized emitter. Caesium atoms from a low pressure vapour atmosphere are absorbed on and migrate from a metallic target rapidly heated by a laser to a high temperature. Due to this heating time being short compared with the residence time of the caesium atoms adsorbed on the target surface, copious electrons are emitted which form a high current density pulse. (U.K.)

Vision 20/20: Mammographic breast density and its clinical applications

International Nuclear Information System (INIS)

Ng, Kwan-Hoong; Lau, Susie

2015-01-01

Breast density is a strong predictor of the failure of mammography screening to detect breast cancer and is a strong predictor of the risk of developing breast cancer. The many imaging options that are now available for imaging dense breasts show great promise, but there is still the question of determining which women are “dense” and what imaging modality is suitable for individual women. To date, mammographic breast density has been classified according to the Breast Imaging-Reporting and Data System (BI-RADS) categories from visual assessment, but this is known to be very subjective. Despite many research reports, the authors believe there has been a lack of physics-led and evidence-based arguments about what breast density actually is, how it should be measured, and how it should be used. In this paper, the authors attempt to start correcting this situation by reviewing the history of breast density research and the debates generated by the advocacy movement. The authors review the development of breast density estimation from pattern analysis to area-based analysis, and the current automated volumetric breast density (VBD) analysis. This is followed by a discussion on seeking the ground truth of VBD and mapping volumetric methods to BI-RADS density categories. The authors expect great improvement in VBD measurements that will satisfy the needs of radiologists, epidemiologists, surgeons, and physicists. The authors believe that they are now witnessing a paradigm shift toward personalized breast screening, which is going to see many more cancers being detected early, with the use of automated density measurement tools as an important component

Vision 20/20: Mammographic breast density and its clinical applications

Energy Technology Data Exchange (ETDEWEB)

Ng, Kwan-Hoong, E-mail: ngkh@ummc.edu.my; Lau, Susie [Department of Biomedical Imaging and University of Malaya Research Imaging Centre, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2015-12-15

Breast density is a strong predictor of the failure of mammography screening to detect breast cancer and is a strong predictor of the risk of developing breast cancer. The many imaging options that are now available for imaging dense breasts show great promise, but there is still the question of determining which women are “dense” and what imaging modality is suitable for individual women. To date, mammographic breast density has been classified according to the Breast Imaging-Reporting and Data System (BI-RADS) categories from visual assessment, but this is known to be very subjective. Despite many research reports, the authors believe there has been a lack of physics-led and evidence-based arguments about what breast density actually is, how it should be measured, and how it should be used. In this paper, the authors attempt to start correcting this situation by reviewing the history of breast density research and the debates generated by the advocacy movement. The authors review the development of breast density estimation from pattern analysis to area-based analysis, and the current automated volumetric breast density (VBD) analysis. This is followed by a discussion on seeking the ground truth of VBD and mapping volumetric methods to BI-RADS density categories. The authors expect great improvement in VBD measurements that will satisfy the needs of radiologists, epidemiologists, surgeons, and physicists. The authors believe that they are now witnessing a paradigm shift toward personalized breast screening, which is going to see many more cancers being detected early, with the use of automated density measurement tools as an important component.

Density diagnostics of ionized outflows in active galacitc nuclei

Science.gov (United States)

Mao, J.; Kaastra, J.; Mehdipour, M.; Raassen, T.; Gu, L.

2017-10-01

Ionized outflows in Active Galactic Nuclei are thought to influence their nuclear and local galactic environment. However, the distance of outflows with respect to the central engine is poorly constrained, which limits our understanding of the kinetic power by the outflows. Therefore, the impact of AGN outflows on their host galaxies is uncertain. Given the density of the outflows, their distance can be immediately obtained by the definition of the ionization parameter. Here we carry out a theoretical study of density diagnostics of AGN outflows using absorption lines from metastable levels in Be-like to F-like ions. With the new self-consistent photoionization model (PION) in the SPEX code, we are able to calculate ground and metastable level populations. This enable us to determine under what physical conditions these levels are significantly populated. We then identify characteristic transitions from these metastable levels in the X-ray band. Firm detections of absorption lines from such metastable levels are challenging for current grating instruments. The next generation of spectrometers like X-IFU onboard Athena will certainly identify the presence/absence of these density- sensitive absorption lines, thus tightly constraining the location and the kinetic power of AGN outflows.

Putting Priors in Mixture Density Mercer Kernels

Science.gov (United States)

Srivastava, Ashok N.; Schumann, Johann; Fischer, Bernd

2004-01-01

This paper presents a new methodology for automatic knowledge driven data mining based on the theory of Mercer Kernels, which are highly nonlinear symmetric positive definite mappings from the original image space to a very high, possibly infinite dimensional feature space. We describe a new method called Mixture Density Mercer Kernels to learn kernel function directly from data, rather than using predefined kernels. These data adaptive kernels can en- code prior knowledge in the kernel using a Bayesian formulation, thus allowing for physical information to be encoded in the model. We compare the results with existing algorithms on data from the Sloan Digital Sky Survey (SDSS). The code for these experiments has been generated with the AUTOBAYES tool, which automatically generates efficient and documented C/C++ code from abstract statistical model specifications. The core of the system is a schema library which contains template for learning and knowledge discovery algorithms like different versions of EM, or numeric optimization methods like conjugate gradient methods. The template instantiation is supported by symbolic- algebraic computations, which allows AUTOBAYES to find closed-form solutions and, where possible, to integrate them into the code. The results show that the Mixture Density Mercer-Kernel described here outperforms tree-based classification in distinguishing high-redshift galaxies from low- redshift galaxies by approximately 16% on test data, bagged trees by approximately 7%, and bagged trees built on a much larger sample of data by approximately 2%.

Sourceless formation evaluation. An LWD solution providing density and neutron measurements without the use of radioisotopes

Energy Technology Data Exchange (ETDEWEB)

Griffiths, R.; Reichel, N. [Schlumberger, Sungai Buloh (Malaysia)

2013-08-01

For many years the industry has been searching for a way to eliminate the logistical difficulties and risk associated with deployment of radioisotopes for formation evaluation. The traditional gamma-gamma density (GGD) measurement uses the scattering of 662-keV gamma rays from a 137Cs radioisotopic source, with a 30.17-year half-life, to determine formation density. The traditional neutron measurement uses an Am-Be source emitting neutrons with an energy around 4 MeV, with a half-life of 432 years. Both these radioisotopic sources pose health, security, and environmental risks. Pulsed-neutron generators have been used in the industry for several decades in wireline tools and more recently in logging-while-drilling tools. These generators produce 14-MeV neutrons, many of which interact with the nuclei in the formation. Elastic collisions allow a neutron porosity measurement to be derived, which has been available to the industry since 2005. Inelastic interactions are typically followed by the emission of a variety of high-energy gamma rays. Similar to the case of the GGD measurement, the transport and attenuation of these gamma rays is a strong function of the formation density. However, the gamma-ray source is now distributed over a volume within the formation, where gamma rays have been induced by neutron interactions and the source can no longer be considered to be a point as in the case of a radioisotopic source. In addition, the extent of the induced source region depends on the transport of the fast neutrons from the source to the point of gamma-ray production. Even though the physics is more complex, it is possible to measure the formation density if the fast neutron transport is taken into account when deriving the density answer. This paper briefly reviews the physics underlying the sourceless neutron porosity and recently introduced neutron-gamma density (SNGD) measurement, demonstrates how they can be used in traditional workflows and illustrates their

Physical model for the generation of ideal resources in multipartite quantum networking

International Nuclear Information System (INIS)

Ciccarello, F.; Zarcone, M.; Paternostro, M.; Bose, S.; Browne, D. E.; Palma, G. M.

2010-01-01

We propose a physical model for generating multipartite entangled states of spin-s particles that have important applications in distributed quantum information processing. Our protocol is based on a process where mobile spins induce the interaction among remote scattering centers. As such, a major advantage lies in the management of stationary and well-separated spins. Among the generable states, there is a class of N-qubit singlets allowing for optimal quantum telecloning in a scalable and controllable way. We also show how to prepare Aharonov, W, and Greenberger-Horne-Zeilinger states.

Modeling and analysis of the disk MHD generator component of a gas core reactor/MHD Rankine cycle space power system

International Nuclear Information System (INIS)

Welch, G.E.; Dugan, E.T.; Lear, W.E. Jr.; Appelbaum, J.G.

1990-01-01

A gas core nuclear reactor (GCR)/disk magnetohydrodynamic (MHD) generator direct closed Rankine space power system concept is described. The GCR/disk MHD generator marriage facilitates efficient high electric power density system performance at relatively high operating temperatures. The system concept promises high specific power levels, on the order of 1 kW e /kg. An overview of the disk MHD generator component magnetofluiddynamic and plasma physics theoretical modeling is provided. Results from a parametric design analysis of the disk MHD generator are presented and discussed

Physical processes in hot cosmic plasmas

International Nuclear Information System (INIS)

Fabian, A.G.; Giovannelli, F.

1990-01-01

The interpretation of many high energy astrophysical phenomena relies on a detailed knowledge of radiation and transport processes in hot plasmas. The understanding of these plasma properties is one of the aims of terrestrial plasma physics. While the microscopic properties of astrophysical plasmas can hardly be determined experimentally, laboratory plasmas are more easily accessible to experimental techniques, but transient phenomena and the interaction of the plasma with boundaries often make the interpretation of measurements cumbersome. This book contains the talks given at the NATO Advanced Research Workshop on astro- and plasma-physics in Vulcano, Sicily, May 29-June 2, 1989. The book focuses on three main areas: radiation transport processes in hot (astrophysical and laboratory) plasmas; magnetic fields; their generation, reconnection and their effects on plasma transport properties; relativistic and ultra-high density plasmas

Transition from wakefield generation to soliton formation

Science.gov (United States)

Holkundkar, Amol R.; Brodin, Gert

2018-04-01

It is well known that when a short laser pulse propagates in an underdense plasma, it induces longitudinal plasma oscillations at the plasma frequency after the pulse, typically referred to as the wakefield. However, for plasma densities approaching the critical density, wakefield generation is suppressed, and instead the EM-pulse (electromagnetic pulse) undergoes nonlinear self-modulation. In this article we have studied the transition from the wakefield generation to formation of quasi-solitons as the plasma density is increased. For this purpose we have applied a one-dimensional relativistic cold fluid model, which has also been compared with particle-in-cell simulations. A key result is that the energy loss of the EM-pulse due to wakefield generation has its maximum for a plasma density of the order 10% of the critical density, but that wakefield generation is sharply suppressed when the density is increased further.

Directional migration of leading-edge mesoderm generates physical forces: Implication in Xenopus notochord formation during gastrulation.

Science.gov (United States)

Hara, Yusuke; Nagayama, Kazuaki; Yamamoto, Takamasa S; Matsumoto, Takeo; Suzuki, Makoto; Ueno, Naoto

2013-10-15

Gastrulation is a dynamic tissue-remodeling process occurring during early development and fundamental to the later organogenesis. It involves both chemical signals and physical factors. Although much is known about the molecular pathways involved, the roles of physical forces in regulating cellular behavior and tissue remodeling during gastrulation have just begun to be explored. Here, we characterized the force generated by the leading edge mesoderm (LEM) that migrates preceding axial mesoderm (AM), and investigated the contribution of LEM during Xenopus gastrulation. First, we constructed an assay system using micro-needle which could measure physical forces generated by the anterior migration of LEM, and estimated the absolute magnitude of the force to be 20-80nN. Second, laser ablation experiments showed that LEM could affect the force distribution in the AM (i.e. LEM adds stretch force on axial mesoderm along anterior-posterior axis). Third, migrating LEM was found to be necessary for the proper gastrulation cell movements and the establishment of organized notochord structure; a reduction of LEM migratory activity resulted in the disruption of mediolateral cell orientation and convergence in AM. Finally, we found that LEM migration cooperates with Wnt/PCP to form proper notochord. These results suggest that the force generated by the directional migration of LEM is transmitted to AM and assists the tissue organization of notochord in vivo independently of the regulation by Wnt/PCP. We propose that the LEM may have a mechanical role in aiding the AM elongation through the rearrangement of force distribution in the dorsal marginal zone. © 2013 Elsevier Inc. All rights reserved.

Proposal and analysis of the benchmark problem suite for reactor physics study of LWR next generation fuels

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-10-01

In order to investigate the calculation accuracy of the nuclear characteristics of LWR next generation fuels, the Research Committee on Reactor Physics organized by JAERI has established the Working Party on Reactor Physics for LWR Next Generation Fuels. The next generation fuels mean the ones aiming for further extended burn-up such as 70 GWd/t over the current design. The Working Party has proposed six benchmark problems, which consists of pin-cell, PWR fuel assembly and BWR fuel assembly geometries loaded with uranium and MOX fuels, respectively. The specifications of the benchmark problem neglect some of the current limitations such as 5 wt% {sup 235}U to achieve the above-mentioned target. Eleven organizations in the Working Party have carried out the analyses of the benchmark problems. As a result, status of accuracy with the current data and method and some problems to be solved in the future were clarified. In this report, details of the benchmark problems, result by each organization, and their comparisons are presented. (author)

HIGH DENSITY QCD WITH HEAVY-IONS

CERN Multimedia

The Addendum 1 to Volume 2 of the CMS Physics TDR has been published The Heavy-Ion analysis group completed the writing of a TDR summarizing the CMS plans in using heavy ion collisions to study high density QCD. The document was submitted to the LHCC in March and presented in the Open Session of the LHCC on May 9th. The study of heavy-ion physics at the LHC is promising to be very exciting. LHC will open a new energy frontier in ultra-relativistic heavy-ion physics. The collision energy of heavy nuclei at sNN = 5.5 TeV will be thirty times larger than what is presently available at RHIC. We will certainly probe quark and gluon matter at unprecedented values of energy density. The prime goal of this research programme is to study the fundamental theory of the strong interaction - Quantum Chromodynamics (QCD) - in extreme conditions of temperature, density and parton momentum fraction (low-x). Such studies, with impressive experimental and theoretical advances in recent years thanks to the wealth of high-qua...

Photonic crystal fibers for supercontinuum generation pumped by a gain-switched CW fiber laser

DEFF Research Database (Denmark)

Larsen, Casper; Noordegraaf, Danny; Hansen, Kim P.

2012-01-01

Supercontinuum generation in photonics crystal fibers (PCFs) pumped by CW lasers yields high spectral power density and average power. However, such systems require very high pump power and long nonlinear fibers. By on/off modulating the pump diodes of the fiber laser, the relaxation oscillations...... of the laser can be exploited to enhance the broadening process. The physics behind the supercontinuum generation is investigated by sweeping the fiber length, the zero dispersion wavelength, and the fiber nonlinearity. We show that by applying gain-switching a high average output power of up to 30 W can...

Physics of intense light ion beams and production of high energy density in matter. Annual report 1994

International Nuclear Information System (INIS)

Bluhm, H.J.

1995-06-01

This report presents the results obtained in 1994 within the FZK-program on 'Physics of intense ion beams and pulsed plasmas'. It describes the present status of the 6 MW, 2 TW pulsed generator KALIF-HELIA, the production and focussing of high power ion beams and numerical simulations and experiments related to the hydrodynamics of beam matter interaction. (orig.) [de

Integrating Unified Gravity Wave Physics into the NOAA Next Generation Global Prediction System

Science.gov (United States)

Alpert, J. C.; Yudin, V.; Fuller-Rowell, T. J.; Akmaev, R. A.

2017-12-01

The Unified Gravity Wave Physics (UGWP) project for the Next Generation Global Prediction System (NGGPS) is a NOAA collaborative effort between the National Centers for Environmental Prediction (NCEP), Environemntal Modeling Center (EMC) and the University of Colorado, Cooperative Institute for Research in Environmental Sciences (CU-CIRES) to support upgrades and improvements of GW dynamics (resolved scales) and physics (sub-grid scales) in the NOAA Environmental Modeling System (NEMS)†. As envisioned the global climate, weather and space weather models of NEMS will substantially improve their predictions and forecasts with the resolution-sensitive (scale-aware) formulations planned under the UGWP framework for both orographic and non-stationary waves. In particular, the planned improvements for the Global Forecast System (GFS) model of NEMS are: calibration of model physics for higher vertical and horizontal resolution and an extended vertical range of simulations, upgrades to GW schemes, including the turbulent heating and eddy mixing due to wave dissipation and breaking, and representation of the internally-generated QBO. The main priority of the UGWP project is unified parameterization of orographic and non-orographic GW effects including momentum deposition in the middle atmosphere and turbulent heating and eddies due to wave dissipation and breaking. The latter effects are not currently represented in NOAA atmosphere models. The team has tested and evaluated four candidate GW solvers integrating the selected GW schemes into the NGGPS model. Our current work and planned activity is to implement the UGWP schemes in the first available GFS/FV3 (open FV3) configuration including adapted GFDL modification for sub-grid orography in GFS. Initial global model results will be shown for the operational and research GFS configuration for spectral and FV3 dynamical cores. †http://www.emc.ncep.noaa.gov/index.php?branch=NEMS

Determination of semi-empirical relationship between the manganese and hydrogen atoms ratio, physical density and concentration in an aqueous solution of manganese sulphate

Energy Technology Data Exchange (ETDEWEB)

Rodrigues Bittencourt, Guilherme, E-mail: bittencourt@ird.gov.b [Instituto de Radioprotecao e Dosimetria LNMRI/IRD/CNEN, Av. Salvador Allende, s/n Recreio dos Bandeirantes, CEP 22780-160, Rio de Janeiro, RJ (Brazil); Souza Patrao, Karla Cristina de, E-mail: karla@ird.gov.b [Instituto de Radioprotecao e Dosimetria LNMRI/IRD/CNEN, Av. Salvador Allende, s/n Recreio dos Bandeirantes, CEP 22780-160, Rio de Janeiro, RJ (Brazil); Passos Leite, Sandro, E-mail: sandro@ird.gov.b [Programa de Engenharia Nuclear/COPPE, Universidade Federal do Rio de Janeiro, Ilha do Fundao, Caixa Postal 68509, 21945-970, Rio de Janeiro, RJ (Brazil); Wagner Pereira, Walsan, E-mail: walsan@ird.gov.b [Instituto de Radioprotecao e Dosimetria LNMRI/IRD/CNEN, Av. Salvador Allende, s/n Recreio dos Bandeirantes, CEP 22780-160, Rio de Janeiro, RJ (Brazil); Simoes da Fonseca, Evaldo, E-mail: evaldo@ird.gov.b [Instituto de Radioprotecao e Dosimetria LNMRI/IRD/CNEN, Av. Salvador Allende, s/n Recreio dos Bandeirantes, CEP 22780-160, Rio de Janeiro, RJ (Brazil)

2010-12-15

The Manganese sulphate solution has been used for neutron metrology through the method of Manganese Bath. This method uses physical parameters of manganese sulphate solution to obtain its corrections. This work established a functional relationship, using the gravimetric method, between those physical parameters: density, concentration and hydrogen to manganese ratio. Comparisons were done between manganese sulphate solution concentration from the Manganese Bath system of Laboratory of Metrology of Ionising Radiation and estimated values from the functional relationship obtained, showing percentage difference of less than 0.1%. This result demonstrates the usefulness in the correlation of the physical values of the solution to the MB.

Results of physics start-up tests of Mochovce and Bohunice units with 2-nd generation Gd fuel (average enrichment 4.87 %)

International Nuclear Information System (INIS)

Polakovic, F.

2015-01-01

There are presented main features of the fuel and the list of experimental neutron-physical characteristics measured during physics start-up tests.All together there were carried out 14 physics start-ups at Bohunice and Mochovce Units with the new type of fuel. Differences between theoretical and experimental neutron-physical characteristics were statistically processed and compared with the tests acceptance criteria. There are summarized results of reactor physics start-ups with 2-nd generation Gd fuel usage [ru

P3: An installation for high-energy density plasma physics and ultra-high intensity laser–matter interaction at ELI-Beamlines

Directory of Open Access Journals (Sweden)

S. Weber

2017-07-01

Full Text Available ELI-Beamlines (ELI-BL, one of the three pillars of the Extreme Light Infrastructure endeavour, will be in a unique position to perform research in high-energy-density-physics (HEDP, plasma physics and ultra-high intensity (UHI (>1022W/cm2 laser–plasma interaction. Recently the need for HED laboratory physics was identified and the P3 (plasma physics platform installation under construction in ELI-BL will be an answer. The ELI-BL 10 PW laser makes possible fundamental research topics from high-field physics to new extreme states of matter such as radiation-dominated ones, high-pressure quantum ones, warm dense matter (WDM and ultra-relativistic plasmas. HEDP is of fundamental importance for research in the field of laboratory astrophysics and inertial confinement fusion (ICF. Reaching such extreme states of matter now and in the future will depend on the use of plasma optics for amplifying and focusing laser pulses. This article will present the relevant technological infrastructure being built in ELI-BL for HEDP and UHI, and gives a brief overview of some research under way in the field of UHI, laboratory astrophysics, ICF, WDM, and plasma optics.

Gamma irradiation effects in low density polyethylene

International Nuclear Information System (INIS)

Ono, Lilian S.; Scagliusi, Sandra R.; Cardoso, Elisabeth E.L.; Lugao, Ademar B.

2011-01-01

Low density polyethylene (LDPE) is obtained from ethylene gas polymerization, being one of the most commercialized polymers due to its versatility and low cost. It's a semi-crystalline polymer, usually inactive at room temperature, capable to attain temperatures within a 80 deg C - 100 deg C range, without changing its physical-chemical properties. LDPE has more resistance when compared to its equivalent High Density Polyethylene (HDPE). LDPE most common applications consist in manufacturing of laboratory materials, general containers, pipes, plastic bags, etc. Gamma radiation is used on polymers in order to modify mechanical and physical-chemical features according to utility purposes. This work aims to the study of gamma (γ) radiation interaction with low density polyethylene to evaluate changes in its physical-chemical properties. Polymer samples were exposed to 5, 10, 15, 20 and 30kGy doses, at room temperature. Samples characterization employed Thermal Analysis, Melt Flow Index, Infrared Spectroscopy and Swelling tests. (author)

VT Building Density - from E911 ESITE

Data.gov (United States)

Vermont Center for Geographic Information — (Link to Metadata) The FacilitiesBuildings_DENSITY data set depicts density for defined types of structures in Vermont. The vector source used to generate the...

69th Scottish Universities Summer School in Physics: LHC phenomenology

CERN Document Server

Glover, Nigel; Robson, Aidan; SUSSP69

2015-01-01

This book covers a very broad spectrum of experimental and theoretical activity in particle physics, from the searches for the Higgs boson and physics beyond the Standard Model, to detailed studies of Quantum Chromodynamics, the B-physics sectors and the properties of hadronic matter at high energy density as realised in heavy-ion collisions. Starting with a basic introduction to the Standard Model and its most likely extensions, the opening section of the book presents an overview of the theoretical and phenomenological framework of hadron collisions, and current theoretical models of frontier physics. In part II, discussion of the theory is supplemented by chapters on the detector capabilities and search strategies, as well as an overview of the main detector components, the initial calibration procedures and physics samples, and early LHC results. Part III completes the volume with a description of the physics behind Monte Carlo event generators, and a broad introduction to the main statistical methods use...

Bone mineral density, muscle strength and physical activity. A population-based study of 332 subjects aged 15-42 years.

Science.gov (United States)

Düppe, H; Gärdsell, P; Johnell, O; Nilsson, B E; Ringsberg, K

1997-04-01

The aim of this population-based study was to find out whether differences in levels of physical activity have an influence on bone mass quantity and whether quadriceps muscle strength is a reliable determinant of bone mass. Included were 175 men and 157 women, aged 15-42 years. Bone mineral density (BMD) was measured at various sites by dual X-ray absorptiometry (DXA) and single photon absorptiometry (SPA). Muscle strength was assessed using an isokinetic muscle force meter. A questionnaire was used to estimate the level of physical activity. We found a positive correlation between physical activity and BMD for boys at the distal forearm and for girls at the trochanter (age group 15-16 years). Active men (age group 21-42 years) had up to 9% higher BMD levels at the hip than those who were less active. Quadriceps muscle torque was not an independent predictor of BMD. Our data suggest that a higher level of physical activity-within the limits of a "normal life style"-may have a positive effect on BMD in the proximal femur of young adults, which in turn may lessen the subsequent risk of fracture.

Alcohol Consumption and the Physical Availability of Take-Away Alcohol: Systematic Reviews and Meta-Analyses of the Days and Hours of Sale and Outlet Density.

Science.gov (United States)

Sherk, Adam; Stockwell, Tim; Chikritzhs, Tanya; Andréasson, Sven; Angus, Colin; Gripenberg, Johanna; Holder, Harold; Holmes, John; Mäkelä, Pia; Mills, Megan; Norström, Thor; Ramstedt, Mats; Woods, Jonathan

2018-01-01

Systematic reviews and meta-analyses were completed studying the effect of changes in the physical availability of take-away alcohol on per capita alcohol consumption. Previous reviews examining this topic have not focused on off-premise outlets where take-away alcohol is sold and have not completed meta-analyses. Systematic reviews were conducted separately for policies affecting the temporal availability (days and hours of sale) and spatial availability (outlet density) of take-away alcohol. Studies were included up to December 2015. Quality criteria were used to select articles that studied the effect of changes in these policies on alcohol consumption with a focus on natural experiments. Random-effects meta-analyses were applied to produce the estimated effect of an additional day of sale on total and beverage-specific consumption. Separate systematic reviews identified seven studies regarding days and hours of sale and four studies regarding density. The majority of articles included in these systematic reviews, for days/hours of sale (7/7) and outlet density (3/4), concluded that restricting the physical availability of take-away alcohol reduces per capita alcohol consumption. Meta-analyses studying the effect of adding one additional day of sale found that this was associated with per capita consumption increases of 3.4% (95% CI [2.7, 4.1]) for total alcohol, 5.3% (95% CI [3.2, 7.4]) for beer, 2.6% (95% CI [1.8, 3.5]) for wine, and 2.6% (95% CI [2.1, 3.2]) for spirits. The small number of included studies regarding hours of sale and density precluded meta-analysis. The results of this study suggest that decreasing the physical availability of take-away alcohol will decrease per capita consumption. As decreasing per capita consumption has been shown to reduce alcohol-related harm, restricting the physical availability of take-away alcohol would be expected to result in improvements to public health.

Schlieren visualization of flow-field modification over an airfoil by near-surface gas-density perturbations generated by a nanosecond-pulse-driven plasma actuator

International Nuclear Information System (INIS)

Komuro, Atsushi; Konno, Kaiki; Ando, Akira; Takashima, Keisuke; Kaneko, Toshiro; Tanaka, Naoki; Nonomura, Taku; Asai, Keisuke

2017-01-01

Gas-density perturbations near an airfoil surface generated by a nanosecond dielectric-barrier-discharge plasma actuator (ns-DBDPA) are visualized using a high-speed Schlieren imaging method. Wind-tunnel experiments are conducted for a wind speed of 20 m s −1 with an NACA0015 airfoil whose chord length is 100 mm. The results show that the ns-DBDPA first generates a pressure wave and then stochastic perturbations of the gas density near the leading edge of the airfoil. Two structures with different characteristics are observed in the stochastic perturbations. One structure propagates along the boundary between the shear layer and the main flow at a speed close to that of the main flow. The other propagates more slowly on the surface of the airfoil and causes mixing between the main and shear flows. It is observed that these two heated structures interact with each other, resulting in a recovery in the negative pressure coefficient at the leading edge of the airfoil. (paper)

Analysis of physical mechanisms underlying density-dependent transport in porous media

NARCIS (Netherlands)

Landman, A.J.

2005-01-01

In this thesis, the interaction between (large) density gradients and flow and transport in porous media is studied. Large gradients in the density of groundwater exist for example near deep salt rock formations, which are considered as possible long-term storage sites for radioactive waste.

Learning Grasp Affordance Densities

DEFF Research Database (Denmark)

Detry, Renaud; Kraft, Dirk; Kroemer, Oliver

2011-01-01

and relies on kernel density estimation to provide a continuous model. Grasp densities are learned and refined from exploration, by letting a robot “play” with an object in a sequence of graspand-drop actions: The robot uses visual cues to generate a set of grasp hypotheses; it then executes......We address the issue of learning and representing object grasp affordance models. We model grasp affordances with continuous probability density functions (grasp densities) which link object-relative grasp poses to their success probability. The underlying function representation is nonparametric...... these and records their outcomes. When a satisfactory number of grasp data is available, an importance-sampling algorithm turns these into a grasp density. We evaluate our method in a largely autonomous learning experiment run on three objects of distinct shapes. The experiment shows how learning increases success...

High energy density capacitors fabricated by thin film technology

International Nuclear Information System (INIS)

Barbee, T W; Johnson, G W; Wagner, A V.

1999-01-01

Low energy density in conventional capacitors severely limits efforts to miniaturize power electronics and imposes design limitations on electronics in general. We have successfully applied physical vapor deposition technology to greatly increase capacitor energy density. The high dielectric breakdown strength we have achieved in alumina thin films allows high energy density to be achieved with this moderately low dielectric constant material. The small temperature dependence of the dielectric constant, and the high reliability, high resistivity, and low dielectric loss of Al 2 O 3 , make it even more appealing. We have constructed single dielectric layer thin film capacitors and shown that they can be stacked to form multilayered structures with no loss in yield for a given capacitance. Control of film growth morphology is critical for achieving the smooth, high quality interfaces between metal and dielectric necessary for device operation at high electric fields. Most importantly, high rate deposition with extremely low particle generation is essential for achieving high energy storage at a reasonable cost. This has been achieved by reactive magnetron sputtering in which the reaction to form the dielectric oxide has been confined to the deposition surface. By this technique we have achieved a yield of over 50% for 1 cm 2 devices with an energy density of 14 J per cubic centimeter of Al 2 O 3 dielectric material in 1.2 kV, 4 nF devices. By further reducing defect density and increasing the dielectric constant of the material, we will be able to increase capacitance and construct high energy density devices to meet the requirements of applications in power electronics

Probing Extreme-density Matter with Gravitational-wave Observations of Binary Neutron Star Merger Remnants

Energy Technology Data Exchange (ETDEWEB)

Radice, David [Institute for Advanced Study, 1 Einstein Drive, Princeton, NJ 08540 (United States); Bernuzzi, Sebastiano [Department of Mathematical, Physical and Computer Sciences, University of Parma, I-43124 Parma (Italy); Pozzo, Walter Del [Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Pisa I-56127 (Italy); Roberts, Luke F. [NSCL/FRIB and Department of Physics and Astronomy, Michigan State University, 640 S Shaw Lane, East Lansing, MI 48824 (United States); Ott, Christian D. [TAPIR, Walter Burke Institute for Theoretical Physics, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125 (United States)

2017-06-20

We present a proof-of-concept study, based on numerical-relativity simulations, of how gravitational waves (GWs) from neutron star merger remnants can probe the nature of matter at extreme densities. Phase transitions and extra degrees of freedom can emerge at densities beyond those reached during the inspiral, and typically result in a softening of the equation of state (EOS). We show that such physical effects change the qualitative dynamics of the remnant evolution, but they are not identifiable as a signature in the GW frequency, with the exception of possible black hole formation effects. The EOS softening is, instead, encoded in the GW luminosity and phase and is in principle detectable up to distances of the order of several megaparsecs with advanced detectors and up to hundreds of megaparsecs with third-generation detectors. Probing extreme-density matter will require going beyond the current paradigm and developing a more holistic strategy for modeling and analyzing postmerger GW signals.

Probing Extreme-density Matter with Gravitational-wave Observations of Binary Neutron Star Merger Remnants

International Nuclear Information System (INIS)

Radice, David; Bernuzzi, Sebastiano; Pozzo, Walter Del; Roberts, Luke F.; Ott, Christian D.

2017-01-01

We present a proof-of-concept study, based on numerical-relativity simulations, of how gravitational waves (GWs) from neutron star merger remnants can probe the nature of matter at extreme densities. Phase transitions and extra degrees of freedom can emerge at densities beyond those reached during the inspiral, and typically result in a softening of the equation of state (EOS). We show that such physical effects change the qualitative dynamics of the remnant evolution, but they are not identifiable as a signature in the GW frequency, with the exception of possible black hole formation effects. The EOS softening is, instead, encoded in the GW luminosity and phase and is in principle detectable up to distances of the order of several megaparsecs with advanced detectors and up to hundreds of megaparsecs with third-generation detectors. Probing extreme-density matter will require going beyond the current paradigm and developing a more holistic strategy for modeling and analyzing postmerger GW signals.

Normal Bone Microstructure and Density But Worse Physical Function in Older Women Treated with Selective Serotonin Reuptake Inhibitors, a Cross-Sectional Population-Based Study.

Science.gov (United States)

Larsson, Berit; Mellström, Dan; Johansson, Lisa; Nilsson, Anna G; Lorentzon, Mattias; Sundh, Daniel

2018-05-05

Depression in the elderly is today often treated with selective serotonin reuptake inhibitors (SSRIs) because of their favorable adverse effect profile. However, treatment with SSRIs is associated with increased risk of fractures. Whether this increased risk depends on reduced bone strength or increased fall risk due to reduced physical function is not certain. The aim was therefore to investigate if treatment with SSRIs is associated with impaired bone microstructure, bone density, or physical function in older women. From an ongoing population-based study, 1057 women (77.7 ± 1.5 years) were included. Validated questionnaires were used to assess information regarding medical history, medications, smoking, mental and physical health, and physical activity. Physical function was measured using clinically used tests: timed up and go, walking speed, grip strength, chair stand test, and one leg standing. Bone mineral density (BMD) was measured at the hip and spine with dual-energy X-ray absorptiometry (Hologic Discovery A). Bone geometry and microstructure were measured at the ultradistal and distal (14%) site of radius and tibia using high-resolution peripheral quantitative computed tomography (HR-pQCT; XtremeCT). Treatment with SSRIs was associated with higher BMD at the femoral neck, total hip, and lumbar spine, whereas no associations were found for any HR-pQCT-derived measurements. The use of SSRIs was associated with lower grip strength, walking speed, and fewer chair stand rises. These associations were valid also after adjustments for known risk factors for falls. Treatment with SSRIs was, independently of covariates, associated with worse physical function without any signs of inferior bone geometry and microstructure.

Algebras Generated by Geometric Scalar Forms and their Applications in Physics and Social Sciences

International Nuclear Information System (INIS)

Keller, Jaime

2008-01-01

The present paper analyzes the consequences of defining that the geometric scalar form is not necessarily quadratic, but in general K-atic, that is obtained from the K th power of the linear form, requiring {e i ;i = 1,...,N;(e i ) K = 1} and d-vector Σ i x i e i . We consider the algebras which are thus generated, for positive integer K, a generalization of the geometric algebras we know under the names of Clifford or Grassmann algebras. We then obtain a set of geometric K-algebras. We also consider the generalization of special functions of geometry which corresponds to the K-order scalar forms (as trigonometric functions and other related geometric functions which are based on the use of quadratic forms). We present an overview of the use of quadratic forms in physics as in our general theory, we have called START. And, in order to give an introduction to the use of the more general K-algebras and to the possible application to sciences other than physics, the application to social sciences is considered.For the applications to physics we show that quadratic spaces are a fundamental clue to understand the structure of theoretical physics (see, for example, Keller in ICNAAM 2005 and 2006).

Mathematics motivated by physics: the electrostatic potential is the Coulomb integral transform of the electric charge density

OpenAIRE

Medina, L; Ley Koo, E

2008-01-01

This article illustrates a practical way to connect and coordinate the teaching and learning of physics and mathematics. The starting point is the electrostatic potential, which is obtained in any introductory course of electromagnetism from the Coulomb potential and the superposition principle for any charge distribution. The necessity to develop solutions to the Laplace and Poisson differential equations is also recognized, identifying the Coulomb potential as the generating function of har...

Bone density and young athletic women. An update.

Science.gov (United States)

Nichols, David L; Sanborn, Charlotte F; Essery, Eve V

2007-01-01

High-school girls and collegiate women have tremendous opportunities to participate in athletic teams. Young girls are also playing in club and select teams at an early age and often, year-round. There are many benefits for participating in sport and physical activity on both the physical and mental health of girls and women. Decreased risk for heart disease and diabetes mellitus, along with improved self-esteem and body-image, were among the first reported benefits of regular physical activity. In addition, sport participation and physical activity is also associated with bone health. Athletes have a greater bone mineral density compared with non-active and physically active females. The increase in bone mass should reduce the risk of fragility fractures in later life. There appears to be a window of opportunity during the development of peak bone mass in which the bone is especially responsive to weight-bearing physical activity. Impact loading sports such as gymnastics, rugby or volleyball tend to produce a better overall osteogenic response than sports without impact loading such as cycling, rowing and swimming. Relatively little is known about the impact of retiring from athletics on bone density. It appears that former athletes continue to have a higher bone density than non-athletes; however, the rate of bone loss appears to be similar in the femoral neck. The positive impact of sports participation on bone mass can be tempered by nutritional and hormonal status. It is not known whether female athletes need additional calcium compared with the general female population. Due to the increased energy expenditure of exercise and/or the pressure to obtain an optimal training bodyweight, some female athletes may develop low energy availability or an eating disorder and subsequently amenorrhoea and a loss of bone mineral density. The three inter-related clinical disorders are referred to as the 'female athlete triad'. This article presents a review of the

Generating Units

Data.gov (United States)

Department of Homeland Security — Generating Units are any combination of physically connected generators, reactors, boilers, combustion turbines, and other prime movers operated together to produce...

Large superconducting wind turbine generators

DEFF Research Database (Denmark)

Abrahamsen, Asger Bech; Magnusson, Niklas; Jensen, Bogi Bech

2012-01-01

and the rotation speed is lowered in order to limit the tip speed of the blades. The ability of superconducting materials to carry high current densities with very small losses might facilitate a new class of generators operating with an air gap flux density considerably higher than conventional generators...... and thereby having a smaller size and weight [1, 2]. A 5 MW superconducting wind turbine generator forms the basics for the feasibility considerations, particularly for the YBCO and MgB2 superconductors entering the commercial market. Initial results indicate that a 5 MW generator with an active weight of 34...

Sustainable income-generating projects for HIV-affected households in Zimbabwe: evidence from two high-density suburbs.

Science.gov (United States)

Mutenje, Munyaradzi J; Nyakudya, Innocent W; Katsinde, Constance; Chikuvire, Tichaedza J

2007-04-01

An estimated 25% of the adults in urban areas of Zimbabwe are living as HIV-positive. In HIV-affected households the need for income increases with the demand for medicines, food and funeral costs. One way to mitigate this effect of the epidemic is by expanding micro enterprises that can enhance the livelihoods of urban households affected by HIV. To identify viable income-generating projects for such households, five possible projects facilitated by two HIV/AIDS support organisations were selected for assessment. These were: selling second-hand clothing, poultry-keeping and nutritional/herbal gardens, freezit-making, mobile kitchens, and payphone set-ups. A case study of 200 households benefiting from one of these projects was done in two high-density suburbs in the town of Bindura, northern Zimbabwe. Information was collected from each household four times per year, over four years (2001-2004). Information on the income generated from the micro enterprises was collected monthly during the period. Descriptive statistics were used to analyse household demographic data; income data was analysed using cost-benefit analysis and analysis of variance. The results show that all five income-generating projects were viable for these households, although some were not feasible for the most vulnerable HIV-affected households. Making more efficient use of micro enterprises can be a valuable part of mainstreaming HIV-affected people and households in urban areas, and so allow people living with HIV to have longer and more meaningful lives.

Energy and physics

Energy Technology Data Exchange (ETDEWEB)

Kapitsa, P L

1976-01-01

The development of large power energy sources is reviewed in the light of fundamental limitations imposed by nature on the energy flux density. The energy sources based on electrostatic generators, gas units (direct conversion of hydrogen oxidation chemical energy to electric one), solar batteries, geothermal energy, wind power and hydroelectric power appear to be unpromising. The solution of the world energy crisis is connected with nuclear energy, and, first of all, with thermonuclear reaction of deuterium and tritium nuclei. In contrast to uranium employment the thermonuclear process produces no significant quantity of radioactive wastes, runs far less risk during accidents and cannot be used as an explosive. The realisation of a controlled thermonuclear reaction is pointed out to face a number of physical and technical problems still to be solved.

Collective Focusing of Intense Ion Beam Pulses for High-energy Density Physics Applications

International Nuclear Information System (INIS)

Dorf, Mikhail A.; Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.

2011-01-01

The collective focusing concept in which a weak magnetic lens provides strong focusing of an intense ion beam pulse carrying a neutralizing electron background is investigated by making use of advanced particle-in-cell simulations and reduced analytical models. The original analysis by Robertson Phys. Rev. Lett. 48, 149 (1982) is extended to the parameter regimes of particular importance for several high-energy density physics applications. The present paper investigates (1) the effects of non-neutral collective focusing in a moderately strong magnetic field; (2) the diamagnetic effects leading to suppression of the applied magnetic field due to the presence of the beam pulse; and (3) the influence of a finite-radius conducting wall surrounding the beam cross-section on beam neutralization. In addition, it is demonstrated that the use of the collective focusing lens can significantly simplify the technical realization of the final focusing of ion beam pulses in the Neutralized Drift Compression Experiment-I (NDCX-I), and the conceptual designs of possible experiments on NDCX-I are investigated by making use of advanced numerical simulations.

Engineering photonic density of states using metamaterials

DEFF Research Database (Denmark)

Jacob, Z.; Kim, J.Y.; Naik, G.V.

2010-01-01

The photonic density of states (PDOS), like its electronic counterpart, is one of the key physical quantities governing a variety of phenomena and hence PDOS manipulation is the route to new photonic devices. The PDOS is conventionally altered by exploiting the resonance within a device such as a......The photonic density of states (PDOS), like its electronic counterpart, is one of the key physical quantities governing a variety of phenomena and hence PDOS manipulation is the route to new photonic devices. The PDOS is conventionally altered by exploiting the resonance within a device...... such as a microcavity or a bandgap structure like a photonic crystal. Here we show that nanostructured metamaterials with hyperbolic dispersion can dramatically enhance the photonic density of states paving the way for metamaterial-based PDOS engineering....

Fundamental physics issues of multilevel logic in developing a parallel processor.

Science.gov (United States)

Bandyopadhyay, Anirban; Miki, Kazushi

2007-06-01

In the last century, On and Off physical switches, were equated with two decisions 0 and 1 to express every information in terms of binary digits and physically realize it in terms of switches connected in a circuit. Apart from memory-density increase significantly, more possible choices in particular space enables pattern-logic a reality, and manipulation of pattern would allow controlling logic, generating a new kind of processor. Neumann's computer is based on sequential logic, processing bits one by one. But as pattern-logic is generated on a surface, viewing whole pattern at a time is a truly parallel processing. Following Neumann's and Shannons fundamental thermodynamical approaches we have built compatible model based on series of single molecule based multibit logic systems of 4-12 bits in an UHV-STM. On their monolayer multilevel communication and pattern formation is experimentally verified. Furthermore, the developed intelligent monolayer is trained by Artificial Neural Network. Therefore fundamental weak interactions for the building of truly parallel processor are explored here physically and theoretically.

Employing online quantum random number generators for generating truly random quantum states in Mathematica

Science.gov (United States)

Miszczak, Jarosław Adam

2013-01-01

The presented package for the Mathematica computing system allows the harnessing of quantum random number generators (QRNG) for investigating the statistical properties of quantum states. The described package implements a number of functions for generating random states. The new version of the package adds the ability to use the on-line quantum random number generator service and implements new functions for retrieving lists of random numbers. Thanks to the introduced improvements, the new version provides faster access to high-quality sources of random numbers and can be used in simulations requiring large amount of random data. New version program summaryProgram title: TRQS Catalogue identifier: AEKA_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKA_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 18 134 No. of bytes in distributed program, including test data, etc.: 2 520 49 Distribution format: tar.gz Programming language: Mathematica, C. Computer: Any supporting Mathematica in version 7 or higher. Operating system: Any platform supporting Mathematica; tested with GNU/Linux (32 and 64 bit). RAM: Case-dependent Supplementary material: Fig. 1 mentioned below can be downloaded. Classification: 4.15. External routines: Quantis software library (http://www.idquantique.com/support/quantis-trng.html) Catalogue identifier of previous version: AEKA_v1_0 Journal reference of previous version: Comput. Phys. Comm. 183(2012)118 Does the new version supersede the previous version?: Yes Nature of problem: Generation of random density matrices and utilization of high-quality random numbers for the purpose of computer simulation. Solution method: Use of a physical quantum random number generator and an on-line service providing access to the source of true random

Impacts of public transit improvements on ridership, and implications for physical activity, in a low-density Canadian city.

Science.gov (United States)

Collins, Patricia A; Agarwal, Ajay

2015-01-01

Public transit ridership offers valuable opportunities for modest amounts of daily physical activity (PA). Transit is a more feasible option for most Canadian commuters who live too far from work to walk or cycle, yet public transit usage in midsized Canadian cities has historically remained low due to inefficient transit service. The objectives of this longitudinal study were threefold: to assess whether the introduction of express transit service in the low-density city of Kingston, Ontario, has translated to greater transit use among a targeted employee group; to document the characteristics of those employees that have shifted to transit; and to examine the PA levels of employees using transit compared to other commute modes. An online survey was administered in October 2013 and October 2014 to all non-student employees at Queen's University. 1356 employees completed the survey in 2013, and 1123 in 2014; 656 of these employees completed the survey both years, constituting our longitudinal sample. Year-round transit ridership increased from 5.5% in 2013 to 8.5% in 2014 (p transit had fewer household-level opportunities to drive to work and more positive attitudes toward transit. Transit commuters accrued an average of 80 minutes/week of commute-related PA, and 50 minutes/week more total PA than those that commuted entirely passively. Kingston Transit's express service has stimulated an increase in transit ridership among one of their target employers, Queen's University. The findings from this study suggest that shifting to transit from entirely passive commuting can generate higher overall PA levels.

Combining image processing and modeling to generate traces of beta-strands from cryo-EM density images of beta-barrels.

Science.gov (United States)

Si, Dong; He, Jing

2014-01-01

Electron cryo-microscopy (Cryo-EM) technique produces 3-dimensional (3D) density images of proteins. When resolution of the images is not high enough to resolve the molecular details, it is challenging for image processing methods to enhance the molecular features. β-barrel is a particular structure feature that is formed by multiple β-strands in a barrel shape. There is no existing method to derive β-strands from the 3D image of a β-barrel at medium resolutions. We propose a new method, StrandRoller, to generate a small set of possible β-traces from the density images at medium resolutions of 5-10Å. StrandRoller has been tested using eleven β-barrel images simulated to 10Å resolution and one image isolated from the experimentally derived cryo-EM density image at 6.7Å resolution. StrandRoller was able to detect 81.84% of the β-strands with an overall 1.5Å 2-way distance between the detected and the observed β-traces, if the best of fifteen detections is considered. Our results suggest that it is possible to derive a small set of possible β-traces from the β-barrel cryo-EM image at medium resolutions even when no separation of the β-strands is visible in the images.

Generator localization by current source density (CSD): Implications of volume conduction and field closure at intracranial and scalp resolutions

Science.gov (United States)

Tenke, Craig E.; Kayser, Jürgen

2012-01-01

The topographic ambiguity and reference-dependency that has plagued EEG/ERP research throughout its history are largely attributable to volume conduction, which may be concisely described by a vector form of Ohm’s Law. This biophysical relationship is common to popular algorithms that infer neuronal generators via inverse solutions. It may be further simplified as Poisson’s source equation, which identifies underlying current generators from estimates of the second spatial derivative of the field potential (Laplacian transformation). Intracranial current source density (CSD) studies have dissected the “cortical dipole” into intracortical sources and sinks, corresponding to physiologically-meaningful patterns of neuronal activity at a sublaminar resolution, much of which is locally cancelled (i.e., closed field). By virtue of the macroscopic scale of the scalp-recorded EEG, a surface Laplacian reflects the radial projections of these underlying currents, representing a unique, unambiguous measure of neuronal activity at scalp. Although the surface Laplacian requires minimal assumptions compared to complex, model-sensitive inverses, the resulting waveform topographies faithfully summarize and simplify essential constraints that must be placed on putative generators of a scalp potential topography, even if they arise from deep or partially-closed fields. CSD methods thereby provide a global empirical and biophysical context for generator localization, spanning scales from intracortical to scalp recordings. PMID:22796039

Generalized Freud's equation and level densities with polynomial

Indian Academy of Sciences (India)

Home; Journals; Pramana – Journal of Physics; Volume 81; Issue 2. Generalized Freud's equation and level densities with polynomial potential. Akshat Boobna Saugata Ghosh. Research Articles Volume 81 ... Keywords. Orthogonal polynomial; Freud's equation; Dyson–Mehta method; methods of resolvents; level density.

Variations of the ionospheric electron density during the Bhuj seismic event

Directory of Open Access Journals (Sweden)

A. Trigunait

2004-12-01

Full Text Available Ionospheric perturbations by natural geophysical activity, such as volcanic eruptions and earthquakes, have been studied since the great Alaskan earthquake in 1964. Measurements made from the ground show a variation of the critical frequency of the ionosphere layers before and after the shock. In this paper, we present an experimental investigation of the electron density variations around the time of the Bhuj earthquake in Gujarat, India. Several experiments have been used to survey the ionosphere. Measurements of fluctuations in the integrated electron density or TEC (Total Electron Content between three satellites (TOPEX-POSEIDON, SPOT2, SPOT4 and the ground have been done using the DORIS beacons. TEC has been also evaluated from a ground-based station using GPS satellites, and finally, ionospheric data from a classical ionospheric sounder located close to the earthquake epicenter are utilized. Anomalous electron density variations are detected both in day and night times before the quake. The generation mechanism of these perturbations is explained by a modification of the electric field in the global electric circuit induced during the earthquake preparation. Key words. Ionosphere (ionospheric disturbances – Radio Science (ionospheric physics – History of geophysics (seismology

Multireference Density Functional Theory with Generalized Auxiliary Systems for Ground and Excited States.

Science.gov (United States)

Chen, Zehua; Zhang, Du; Jin, Ye; Yang, Yang; Su, Neil Qiang; Yang, Weitao

2017-09-21

To describe static correlation, we develop a new approach to density functional theory (DFT), which uses a generalized auxiliary system that is of a different symmetry, such as particle number or spin, from that of the physical system. The total energy of the physical system consists of two parts: the energy of the auxiliary system, which is determined with a chosen density functional approximation (DFA), and the excitation energy from an approximate linear response theory that restores the symmetry to that of the physical system, thus rigorously leading to a multideterminant description of the physical system. The electron density of the physical system is different from that of the auxiliary system and is uniquely determined from the functional derivative of the total energy with respect to the external potential. Our energy functional is thus an implicit functional of the physical system density, but an explicit functional of the auxiliary system density. We show that the total energy minimum and stationary states, describing the ground and excited states of the physical system, can be obtained by a self-consistent optimization with respect to the explicit variable, the generalized Kohn-Sham noninteracting density matrix. We have developed the generalized optimized effective potential method for the self-consistent optimization. Among options of the auxiliary system and the associated linear response theory, reformulated versions of the particle-particle random phase approximation (pp-RPA) and the spin-flip time-dependent density functional theory (SF-TDDFT) are selected for illustration of principle. Numerical results show that our multireference DFT successfully describes static correlation in bond dissociation and double bond rotation.

Solar Mikheyev-Smirnov-Wolfenstein effect with three generations of neutrinos

International Nuclear Information System (INIS)

Osland, Per; Wu, Tai Tsun

2000-01-01

Under the assumption that the density variation of the electrons can be approximated by an exponential function, the solar Mikheyev-Smirnov-Wolfenstein effect is treated for three generations of neutrinos. The generalized hypergeometric functions that result from the exact solution of this problem are studied in detail, and a method for their numerical evaluation is presented. This analysis plays a central role in the determination of neutrino masses, not only the differences of their squares, under the assumption of universal quark-lepton mixing. (c) 2000 The American Physical Society

Electronic structure and physical properties of ScN in pressure: density-functional theory calculations

International Nuclear Information System (INIS)

Guan Pengfei; Wang Chongyu; Yu Tao

2008-01-01

Local density functional is investigated by using the full-potential linearized augmented plane wave (FP-LAPW) method for ScN in the hexagonal structure and the rocksalt structure and for hexagonal structures linking a layered hexagonal phase with wurtzite structure along a homogeneous strain transition path. It is found that the wurtzite ScN is unstable and the layered hexagonal phase, labelled as h o , in which atoms are approximately fivefold coordinated, is metastable, and the rocksalt ScN is stable. The electronic structure, the physical properties of the intermediate structures and the energy band structure along the transition are presented. It is found that the band gaps change from 4.0 to 1.0 eV continuously when c/a value varies from 1.68 to 1.26. It is noticeable that the study of ScN provides an opportunity to apply this kind of material (in wurtzite[h]-derived phase). (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Theory for the asymmetry in the auroral ionization density profile for the generation of auroral infrasonic waves

International Nuclear Information System (INIS)

Goodwin, P.A.

1979-01-01

Traveling pressure waves with periods from 10 to 100 seconds are generated in the lower ionosphere by auroral electrojet current filaments as they move supersonically in an equatorward direction. The infrasonic waves produced by the auroral motions propagate to the ground as highly directional bow waves that can be detected by infrasonic microphones on the surface. There is an asymmetry in the reception of auroral infrasonic waves (AIW) with respect to whether the auroral arcs are moving equatorward to poleward. In the literature it is suggested that the asymmetry may be due to anisotropic propagation conditions along the acoustic ray path from the E-region, where AIW are produced, to the surface. Some intrinsic property of the AIW generation mechanism itself has also been suggested as a possible explanation. In this thesis anisotropic propagation is eliminated as the cause of the AIW reception asymmetry. Theoretical calculations, beginning with a model of an auroral precipitation region, are presented to show that there can be a significant difference in the transverse ionization density profiles between an auroral arc that is moving equatorward and an arc that is moving poleward, for a given equatorward-directed E-region ambient electric field. The calculation has been accomplished by solving the equations of motion and continuity for the cross-sectional ionization density profile associated with the transverse motion of a filamentary auroral electrojet. Thus, it is shown that there is an asymmetry in the ionization profiles associated with moving arcs, and in their coupling, that is related to the relative direction of motion of the arc with respect to the ambient electric field, and that it is this asymmetry that is probably the cause of the observed AIW reception asymmetry

Influence of light energy density on heat generation during photoactivation of dental composites with different dentin and composite thickness

Directory of Open Access Journals (Sweden)

Ricardo Danil Guiraldo

2009-08-01

Full Text Available OBJECTIVE: The aim of this study was to determine the influence of different energy densities on the heat generated during photoactivation of Filtek Z250 (3M/ESPE and Z100 (3M/ESPE composite resins with different dentin and composite thickness. MATERIAL AND METHODS: The temperature increase was registered with a type-K thermocouple connected to a digital thermometer (Iopetherm 46. A chemically polymerized acrylic resin base was prepared to serve as a guide for the thermocouple and as a support for 0.5-, 1.0-, and 1.5-mm-thick bovine dentin discs. Circular elastomer molds (1.0 mm-height x 3.0-mm diameter or 2.0-mm height x 3.0-mm diameter were adapted on the acrylic resin base to standardize the composite resin thickness. A conventional halogen light-curing unit (XL 2500, 3M/ESPE was used with light intensity of 700 mW/cm². Energy density was calculated by the light intensity applied during a certain time with values of 28 J/cm² for Z100 and 14 J/cm² for Filtek Z250. The temperature change data were subjected to three-way ANOVA and Tukey's test at 5% level. RESULTS: The higher energy density (Z100 promoted greater temperature increase (p<0.05 than the lower energy density (Filtek Z250. For both composites and all composite thicknesses, the lowest dentin thickness (0.5 mm yielded significantly higher (p<0.05 temperature increase than the other two dentin thicknesses. The 1-mm-thick composite resin layer yielded significantly higher (p<0.05 temperature changes for both composites and all dentin thicknesses. CONCLUSIONS: Temperature increase was influenced by higher energy density and dentin/composite thickness.

Surface Snow Density of East Antarctica Derived from In-Situ Observations

Science.gov (United States)

Tian, Y.; Zhang, S.; Du, W.; Chen, J.; Xie, H.; Tong, X.; Li, R.

2018-04-01

Models based on physical principles or semi-empirical parameterizations have used to compute the firn density, which is essential for the study of surface processes in the Antarctic ice sheet. However, parameterization of surface snow density is often challenged by the description of detailed local characterization. In this study we propose to generate a surface density map for East Antarctica from all the filed observations that are available. Considering that the observations are non-uniformly distributed around East Antarctica, obtained by different methods, and temporally inhomogeneous, the field observations are used to establish an initial density map with a grid size of 30 × 30 km2 in which the observations are averaged at a temporal scale of five years. We then construct an observation matrix with its columns as the map grids and rows as the temporal scale. If a site has an unknown density value for a period, we will set it to 0 in the matrix. In order to construct the main spatial and temple information of surface snow density matrix we adopt Empirical Orthogonal Function (EOF) method to decompose the observation matrix and only take first several lower-order modes, because these modes already contain most information of the observation matrix. However, there are a lot of zeros in the matrix and we solve it by using matrix completion algorithm, and then we derive the time series of surface snow density at each observation site. Finally, we can obtain the surface snow density by multiplying the modes interpolated by kriging with the corresponding amplitude of the modes. Comparative analysis have done between our surface snow density map and model results. The above details will be introduced in the paper.

Physical Layer Secret-Key Generation Scheme for Transportation Security Sensor Network.

Science.gov (United States)

Yang, Bin; Zhang, Jianfeng

2017-06-28

Wireless Sensor Networks (WSNs) are widely used in different disciplines, including transportation systems, agriculture field environment monitoring, healthcare systems, and industrial monitoring. The security challenge of the wireless communication link between sensor nodes is critical in WSNs. In this paper, we propose a new physical layer secret-key generation scheme for transportation security sensor network. The scheme is based on the cooperation of all the sensor nodes, thus avoiding the key distribution process, which increases the security of the system. Different passive and active attack models are analyzed in this paper. We also prove that when the cooperative node number is large enough, even when the eavesdropper is equipped with multiple antennas, the secret-key is still secure. Numerical results are performed to show the efficiency of the proposed scheme.

Self generation, small generation, and embedded generation issues

International Nuclear Information System (INIS)

2001-01-01

The New Brunswick Market Design Committee for electric power restructuring has been directed to examine issues regarding cogeneration and small-scale, on-site generation and how they will fit within the framework of the bilateral contract market. The Committee will also have to deal with issues of generation embedded in a distribution system. The Committee has defined cogeneration as the simultaneous production of electricity and useful thermal energy. Self-generation has been defined as small-scale power generation by an end-user, while embedded generation has been defined as a generation facility that is located within a distribution utility but is not directly connected to the transmission system. The Committee has postponed its decision on whether embedded generation will be eligible to participate under the bilateral contract market for electricity. This report discusses general issues such as the physical support of generation, market support of generation, transition issues and policy issues. It also discusses generation support issues such as operating reserves, transmission tariff issues, and distribution tariffs. Market support issues such as transmission access for generation sales were also considered, along with market access for generation sales, and net metering for behind the meter generation. 7 refs., 1 tab

Influence of lifestyle factors on mammographic density in postmenopausal women.

Directory of Open Access Journals (Sweden)

Judith S Brand

Full Text Available BACKGROUND: Mammographic density is a strong risk factor for breast cancer. Apart from hormone replacement therapy (HRT, little is known about lifestyle factors that influence breast density. METHODS: We examined the effect of smoking, alcohol and physical activity on mammographic density in a population-based sample of postmenopausal women without breast cancer. Lifestyle factors were assessed by a questionnaire and percentage and area measures of mammographic density were measured using computer-assisted software. General linear models were used to assess the association between lifestyle factors and mammographic density and effect modification by body mass index (BMI and HRT was studied. RESULTS: Overall, alcohol intake was positively associated with percent mammographic density (P trend  = 0.07. This association was modified by HRT use (P interaction  = 0.06: increasing alcohol intake was associated with increasing percent density in current HRT users (P trend  = 0.01 but not in non-current users (P trend  = 0.82. A similar interaction between alcohol and HRT was found for the absolute dense area, with a positive association being present in current HRT users only (P interaction  = 0.04. No differences in mammographic density were observed across categories of smoking and physical activity, neither overall nor in stratified analyses by BMI and HRT use. CONCLUSIONS: Increasing alcohol intake is associated with an increase in mammography density, whereas smoking and physical activity do not seem to influence density. The observed interaction between alcohol and HRT may pose an opportunity for HRT users to lower their mammographic density and breast cancer risk.

ANGARA-5-1 program development on superfast liner implosion for ICF physics study and basic research

Energy Technology Data Exchange (ETDEWEB)

Branitskij, A V; Grabovskij, E V; Fedulov, M V [Troitsk Inst. for Innovation and Thermonuclear Investigation, Troitsk (Russian Federation); and others

1997-12-31

A double liner concept is proposed of utilizing pulsed power in investigations of Inertial Confinement Fusion (ICF) and High Energy Density Physics. In this project, an external cylindrical plasma shell (liner) magnetically imploded in the generator diode collides with the internal one. Thermal X-ray radiation brought about by a high-velocity shock wave penetrates into the internal liner cavity and irradiates a spherical target. Investigations at the ANGARA-5 generator were concentrated on a comprehensive study of physical processes and the possibility of short radiation pulse generation. Soft X-ray radiation intensities of up to 3 TW/cm{sup 2} with a 3 ns rise time were obtained. It follows from the theoretical model that for the generator current higher than 15 MA the radiation intensity should be close to the ignition threshold and magnetized plasma instabilities should be suppressed. The paper reports on the concept and the theoretical and experimental results. (author). 8 refs.

Welfare of African catfish : effects of stocking density

NARCIS (Netherlands)

Nieuwegiessen, van de P.G.

2009-01-01

The general aim of this thesis was to determine the impact of stocking density on welfare indicators in African catfish, Clarias gariepinus, cultured in a recirculating aquaculture system. The following factors were studied: 1) the effects of stocking density on physical, physiological, and

Progress on Implementing Additional Physics Schemes into MPAS-A v5.1 for Next Generation Air Quality Modeling

Science.gov (United States)

The U.S. Environmental Protection Agency (USEPA) has a team of scientists developing a next generation air quality modeling system employing the Model for Prediction Across Scales – Atmosphere (MPAS-A) as its meteorological foundation. Several preferred physics schemes and ...

Resonant transducers for solid-state plasma density modulation

Energy Technology Data Exchange (ETDEWEB)

Hallock, Gary A., E-mail: hallock@ece.utexas.edu [The University of Texas at Austin, Austin, Texas 78701 (United States); Meier, Mark A., E-mail: mark.a.meier@exxonmobil.com [ExxonMobil Upstream Research Company, Houston, Texas 77389 (United States)

2016-04-15

We have developed transducers capable of modulating the plasma density and plasma density gradients in indium antimonide. These transducers make use of piezoelectric drivers to excite acoustic pressure resonance at 3λ/2, generating large amplitude standing waves and plasma density modulations. The plasma density has been directly measured using a laser diagnostic. A layered media model shows good agreement with the experimental measurements.

Quantal density functional theory

CERN Document Server

Sahni, Viraht

2016-01-01

This book deals with quantal density functional theory (QDFT) which is a time-dependent local effective potential theory of the electronic structure of matter. The treated time-independent QDFT constitutes a special case. In the 2nd edition, the theory is extended to include the presence of external magnetostatic fields. The theory is a description of matter based on the ‘quantal Newtonian’ first and second laws which is in terms of “classical” fields that pervade all space, and their quantal sources. The fields, which are explicitly defined, are separately representative of electron correlations due to the Pauli exclusion principle, Coulomb repulsion, correlation-kinetic, correlation-current-density, and correlation-magnetic effects. The book further describes Schrödinger theory from the new physical perspective of fields and quantal sources. It also describes traditional Hohenberg-Kohn-Sham DFT, and explains via QDFT the physics underlying the various energy functionals and functional derivatives o...

Relativistic density functional theory with picture-change corrected electron density based on infinite-order Douglas-Kroll-Hess method

Science.gov (United States)

Oyama, Takuro; Ikabata, Yasuhiro; Seino, Junji; Nakai, Hiromi

2017-07-01

This Letter proposes a density functional treatment based on the two-component relativistic scheme at the infinite-order Douglas-Kroll-Hess (IODKH) level. The exchange-correlation energy and potential are calculated using the electron density based on the picture-change corrected density operator transformed by the IODKH method. Numerical assessments indicated that the picture-change uncorrected density functional terms generate significant errors, on the order of hartree for heavy atoms. The present scheme was found to reproduce the energetics in the four-component treatment with high accuracy.

Microscopic and Beyond-Mean-Field Constraints for a New Generation of Nuclear Energy Density Functionals

International Nuclear Information System (INIS)

Lesinski, Th.

2008-09-01

Nuclear structure is subject to a major renewal linked with the development of radioactive ion beams (such as the SPIRAL 1 and 2 beams at GANIL). Mean-field and density-functional methods are among the best suited for studying nuclei produced at such facilities. The present work aims at demonstrating how existing functionals can be improved so as to exhibit a better predictive power in little-explored regions of the nuclear chart. We propose a better description of the isospin-dependence of the effective interaction, and examine the relevance of adding a tensor coupling. We also show how a new generation of functionals can be better constrained by considering results obtained beyond the mean-field approximation. Finally, we attempt establishing a link with the bare nucleon-nucleon potential for the description of pairing, thus participating in the construction of a non-empirical functional. (author)

High-density limit of quantum chromodynamics

International Nuclear Information System (INIS)

Alvarez, E.

1983-01-01

By means of a formal expansion of the partition function presumably valid at large baryon densities, the propagator of the quarks is expressed in terms of the gluon propagator. This result is interpreted as implying that correlations between quarks and gluons are unimportant at high enough density, so that a kind of mean-field approximation gives a very accurate description of the physical system

The effect of physical water quality and water level changes on the occurrence and density of Anopheles mosquito larvae around the shoreline of the Koka reservoir, central Ethiopia

Directory of Open Access Journals (Sweden)

S. Kibret

2010-12-01

Full Text Available Entomological studies to determine the effect of the physical characteristics of mosquito larval breeding water bodies and reservoir water level changes on the occurrence of Anopheles mosquito larvae were conducted in two villages at Koka reservoir in central Ethiopia between August and December 2007. Of the two study villages, Ejersa is located close to the reservoir, and Kuma is 5 km away from it. Data on the type, number and physical characteristics of Anopheles larval breeding habitat, species composition and densities of anopheles mosquitoes in and around the study villages were investigated and recorded. Meteorological and reservoir water level data were compared with availability of Anopheles larval breeding sites and densities. Entomological data, derived from weekly larval collections, showed that Anopheles pharoensis Theobald, Anopheles gambiae s.l. Giles, Anopheles coustani Laveran and Anopheles squamosus Theobald were breeding in the study area. The mean larval density of An. gambiae s.l. in this study was higher in slightly turbid and shallow aquatic habitat than in turbid and relatively deep aquatic habitat. The density of An. pharoensis in habitat with floating vegetation and with relatively shady conditions was significantly higher than that of less shaded aquatic habitat and greater emergent vegetation. There was also a positive correlation between the occurrence of Anopheles larvae with the water and daily minimum atmospheric temperature. Similarly at Ejersa, over the sampling period, there was a positive correlation between falling reservoir water levels and the number of positive breeding habitats. These results confirm that physical characteristics of the water bodies play an important role in the species composition, total Anopheles larval count, and the density of Anopheles mosquitoes. Suitable breeding habitat in the vicinity of the reservoir village was strongly associated with the reservoir. This is particularly

Community structure, phytoplankton density and physical-chemical factor of batang palangki waters of sijunjung regency, west sumatera

Science.gov (United States)

Gusmaweti; Deswati, L.

2018-03-01

The long-term goal of this study is to provide an overview of the presence of phytoplankton in support of its functions in the waters of Batang Palangki as a conservation area of information on river water management, especially for Batang Palangki stakeholders. Specific targets to be achieved in achieving these objectives are (1) to know the density of phytoplankton, index of diversity of species, equitabilty index, domination index, and in Batang Palangki waters, and (2) to analyze the chemical and physical factors of the waters. The sampling method of phytoplankton is purposive sampling. The phytoplankton sampling is done By filtering 100 liters of water into the net plankton no 25 and filtered into the 25 cc, and then identified. The determination of water quality such as water temperature, water pH and watercolour. dissolved oxygen (DO) and BOD, and Hg content (mercury). The results showed that phytoplankton found from each of station was 370 individualis per liter with the highest density found in the station I of 155. The number of genus was 7, namely Neidium, Gyrogsima, Synedra, Frustulia, Fragillaria, Nitzschia and Peridinium. The diversity index averaged at 0.45, equabilty index averaged at 0.54, while the dominance index averaged at 0.28. Physical and chemical factor measurement results found that water temperature averaged at 26 °C, transparency ranged from 12 - 30 cm, velocity speed ranged from 8 - 15 m/s, while chemical factors such as DO, BOD, and COD ranged from 5.25 to 5.96 mg/L, 3.28 - 3.49 mg/L, and 47.05 - 76.25 mg/L respectively. Likewise, TOM measured in this research was 9.61 - 2.10 mg/L while Hg content ranged from 0.098 - 0.208 mg/L.

A third-generation density-functional-theory-based method for calculating canonical molecular orbitals of large molecules.

Science.gov (United States)

Hirano, Toshiyuki; Sato, Fumitoshi

2014-07-28

We used grid-free modified Cholesky decomposition (CD) to develop a density-functional-theory (DFT)-based method for calculating the canonical molecular orbitals (CMOs) of large molecules. Our method can be used to calculate standard CMOs, analytically compute exchange-correlation terms, and maximise the capacity of next-generation supercomputers. Cholesky vectors were first analytically downscaled using low-rank pivoted CD and CD with adaptive metric (CDAM). The obtained Cholesky vectors were distributed and stored on each computer node in a parallel computer, and the Coulomb, Fock exchange, and pure exchange-correlation terms were calculated by multiplying the Cholesky vectors without evaluating molecular integrals in self-consistent field iterations. Our method enables DFT and massively distributed memory parallel computers to be used in order to very efficiently calculate the CMOs of large molecules.

Loading factor and inclination parameter of diagonal type MHD generators

International Nuclear Information System (INIS)

Ishikawa, Motoo

1979-01-01

Regarding diagonal type MHD generators is studied the relation between the loading factor and inclination parameter which is required for attaining the maximum power density with a given electrical efficiency on the assumption of infinitely segmented electrodes. The average current density on electrodes is calculated against the Hall parameter, loading factor, and inclination parameter. The diagonal type generator is compared with Faraday type generator regarding the average current density. Decreasing the loading factor from inlet to outlet is appropriate to small size generators but increasing to large size generators. The inclination parameter had better decrease in both generators, being smaller for small generators than for large ones. The average current density on electrodes of diagonal type generators varies less with the loading factor than the Faraday type. In large size generators its value can become smaller compared with that of the Faraday type. (author)

Quantum Chromodynamics and Nuclear Physics at Extreme Energy Density

Energy Technology Data Exchange (ETDEWEB)

Mueller, B.; Bass, S.A.; Chandrasekharan, S.; Mehen, T.; Springer, R.P.

2005-11-07

The report describes research in theoretical quantum chromodynamics, including effective field theories of hadronic interactions, properties of strongly interacting matter at extreme energy density, phenomenology of relativistic heavy ion collisions, and algorithms and numerical simulations of lattice gauge theory and other many-body systems.

Quantum Chromodynamics and Nuclear Physics at Extreme Energy Density

International Nuclear Information System (INIS)

Mueller, B.; Bass, S.A.; Chandrasekharan, S.; Mehen, T.; Springer, R.P.

2005-01-01

The report describes research in theoretical quantum chromodynamics, including effective field theories of hadronic interactions, properties of strongly interacting matter at extreme energy density, phenomenology of relativistic heavy ion collisions, and algorithms and numerical simulations of lattice gauge theory and other many-body systems.

Physical modelling of tsunamis generated by three-dimensional deformable granular landslides on planar and conical island slopes.

Science.gov (United States)

McFall, Brian C; Fritz, Hermann M

2016-04-01

Tsunamis generated by landslides and volcanic island collapses account for some of the most catastrophic events recorded, yet critically important field data related to the landslide motion and tsunami evolution remain lacking. Landslide-generated tsunami source and propagation scenarios are physically modelled in a three-dimensional tsunami wave basin. A unique pneumatic landslide tsunami generator was deployed to simulate landslides with varying geometry and kinematics. The landslides were generated on a planar hill slope and divergent convex conical hill slope to study lateral hill slope effects on the wave characteristics. The leading wave crest amplitude generated on a planar hill slope is larger on average than the leading wave crest generated on a convex conical hill slope, whereas the leading wave trough and second wave crest amplitudes are smaller. Between 1% and 24% of the landslide kinetic energy is transferred into the wave train. Cobble landslides transfer on average 43% more kinetic energy into the wave train than corresponding gravel landslides. Predictive equations for the offshore propagating wave amplitudes, periods, celerities and lengths generated by landslides on planar and divergent convex conical hill slopes are derived, which allow an initial rapid tsunami hazard assessment.

Posts, pics, or polls? Which post type generates the greatest engagement in a Facebook physical activity intervention?

Science.gov (United States)

Edney, Sarah; Looyestyn, Jemma; Ryan, Jillian; Kernot, Jocelyn; Maher, Carol

2018-04-05

Social networking websites have attracted considerable attention as a delivery platform for physical activity interventions. Current evidence highlights a need to enhance user engagement with these interventions to actualize their potential. The purpose of this study was to determine which post type generates the most engagement from participants and whether engagement was related to change in physical activity in an intervention delivered via Facebook. Subgroup analysis of the intervention condition of a randomized controlled trial was conducted. The group moderator posted a new message to the private Facebook group each day of the program. The Facebook posts (n = 118) were categorized into the following types: moderator-initiated running program, multimedia, motivational, opinion polls, or discussion question and participant-initiated experience shares, or questions. Four metrics were used to measure volume of engagement with each post type, "likes," "comments," "poll votes," and "photo uploads." One-way ANOVA was used to determine whether engagement differed by post type and an independent samples t-test to determine differences in engagement between moderator and participant-initiated posts. Pearson correlation was used to examine associations between total engagement and change in physical activity. Engagement varied by post type. Polls elicited the greatest engagement (p ≤ .01). The most common form of engagement was "likes," and engagement was higher for moderator-initiated rather than participant-initiated posts (mean = 8.0 [SD 6.8] vs. 5.3 [SD 3.2]; p ≤ .01). Total engagement with the Facebook group was not directly associated with change in physical activity (r = -.13, p = .47). However, engagement was associated with compliance with the running program (r = .37, p = .04) and there was a nonsignificant positive association between compliance and change in physical activity (r = .32, p = .08). Posts requiring a simple response generated the most

The influence of self-generated emotions on physical performance: an investigation of happiness, anger, anxiety, and sadness.

Science.gov (United States)

Rathschlag, Marco; Memmert, Daniel

2013-04-01

The present study examined the relationship between self-generated emotions and physical performance. All participants took part in five emotion induction conditions (happiness, anger, anxiety, sadness, and an emotion-neutral state) and we investigated their influence on the force of the finger musculature (Experiment 1), the jump height of a counter-movement jump (Experiment 2), and the velocity of a thrown ball (Experiment 3). All experiments showed that participants could produce significantly better physical performances when recalling anger or happiness emotions in contrast to the emotion-neutral state. Experiments 1 and 2 also revealed that physical performance in the anger and the happiness conditions was significantly enhanced compared with the anxiety and the sadness conditions. Results are discussed in relation to the Lazarus (1991, 2000a) cognitive-motivational-relational (CMR) theory framework.

Development of a Nomarski-type multi-frame interferometer as a time and space resolving diagnostics for the free electron density of laser-generated plasma

International Nuclear Information System (INIS)

Boerner, M.; Frank, A.; Pelka, A.; Schaumann, G.; Schoekel, A.; Schumacher, D.; Roth, M.; Fils, J.; Blazevic, A.; Hessling, T.; Basko, M. M.; Maruhn, J.; Tauschwitz, An.

2012-01-01

This article reports on the development and set-up of a Nomarski-type multi-frame interferometer as a time and space resolving diagnostics of the free electron density in laser-generated plasma. The interferometer allows the recording of a series of 4 images within 6 ns of a single laser-plasma interaction. For the setup presented here, the minimal accessible free electron density is 5 x 10 18 cm -3 , the maximal one is 2 x 10 20 cm -3 . Furthermore, it provides a resolution of the electron density in space of 50 μm and in time of 0.5 ns for one image with a customizable magnification in space for each of the 4 images. The electron density was evaluated from the interferograms using an Abel inversion algorithm. The functionality of the system was proven during first experiments and the experimental results are presented and discussed. A ray tracing procedure was realized to verify the interferometry pictures taken. In particular, the experimental results are compared to simulations and show excellent agreement, providing a conclusive picture of the evolution of the electron density distribution.

Lower extremity physical performance and hip bone mineral density in elderly black and white men and women : cross-sectional associations in the Health ABC Study

NARCIS (Netherlands)

Taaffe, Dennis R; Simonsick, Eleanor M; Visser, Marjolein; Volpato, Stefano; Nevitt, Michael C; Cauley, Jane A; Tylavsky, Frances A; Harris, Tamara B

2003-01-01

BACKGROUND: Aging is characterized by declines in physical capacity and bone mineral density (BMD), both of which contribute to increased risk for fracture. However, it is unclear if these factors coexist or are independent in elderly people, and if a relationship does exist, whether it varies by

Improving information density in ferroelectric polymer films by using nanoimprinted gratings

Science.gov (United States)

Martínez-Tong, Daniel E.; Soccio, Michela; Rueda, Daniel R.; Nogales, Aurora; García-Gutiérrez, Mari Cruz; Ezquerra, Tiberio A.

2015-03-01

The development of polymer non-volatile memories depends on the effective fabrication of devices with high density of information. Well-defined low aspect ratio nanogratings on thin films of poly(vinylidene fluoride-trifluoroethylene) copolymers can be fabricated by using Nanoimprint Lithography (NIL). By using these nanogratings, an improved management of writing and reading information can be reached as revealed by Piezoresponse Force Microscopy (PFM). Structural investigation by means of Grazing Incidence X-ray (GIX) scattering techniques indicates that the physical confinement generated by nanoimprint promotes the development of smaller and edge-on oriented crystals. Our results evidence that one-dimensional nanostructuring can be a straightforward approach to improve the control of the polarization in ferroelectric polymer thin films.

CSR of Lanzhou and nuclear physics at high densities

International Nuclear Information System (INIS)

Zhuang Pengfei; Zhao Weiqin

1999-01-01

The possibility to produce highly dense nuclear matter at CSR of Lanzhou and the corresponding signals at final state are discussed. Especially, the maximum baryon density reached at CSR is estimated, and the subthreshold production and hadronic flow risen from the partial restoration of chiral symmetry at CSR energies are analyzed

Review of Micro Magnetic Generator

OpenAIRE

Lin DU; Gengchen SHI; Jingjing ZHAO

2014-01-01

This paper discusses the research progress of micro magnetic generator systems. Micro magnetic generator systems convert energy from the environment to electric energy with advantages as high reliability, high power density, long life time and can be applied to extreme environment. This paper summarizes methods for improving generator performance of micro magnetic generator, including rotational magnetic generator, vibrational magnetic generator and hybrid magnetic generator, analyzes and com...

The physics of fast Z pinches

International Nuclear Information System (INIS)

Ryutov, D.D.; Derzon, M.S.; Matzen, M.K.

1998-07-01

The spectacular progress made during the last few years in reaching high energy densities in fast implosions of annular current sheaths (fast Z pinches) opens new possibilities for a broad spectrum of experiments, from x-ray generation to controlled thermonuclear fusion and astrophysics. Presently Z pinches are the most intense laboratory X ray sources (1.8 MJ in 5 ns from a volume 2 mm in diameter and 2 cm tall). Powers in excess of 200 TW have been obtained. This warrants summarizes the present knowledge of physics that governs the behavior of radiating current-carrying plasma in fast Z-pinches. This survey covers essentially all aspects of the physics of fast Z pinches: initiation, instabilities of the early stage, magnetic Rayleigh-Taylor instability in the implosion phase, formation of a transient quasi-equilibrium near the stagnation point, and rebound. Considerable attention is paid to the analysis of hydrodynamic instabilities governing the implosion symmetry. Possible ways of mitigating these instabilities are discussed. Non-magnetohydrodynamic effects (anomalous resistivity, generation of particle beams, etc.) are summarized. Various applications of fast Z pinches are briefly described. Scaling laws governing development of more powerful Z pinches are presented. The survey contains 52 figures and nearly 300 references

The Physics of Fast Z Pinches

Energy Technology Data Exchange (ETDEWEB)

RYUTOV,D.D.; DERZON,MARK S.; MATZEN,M. KEITH

1999-10-25

The spectacular progress made during the last few years in reaching high energy densities in fast implosions of annular current sheaths (fast Z pinches) opens new possibilities for a broad spectrum of experiments, from x-ray generation to controlled thermonuclear fusion and astrophysics. Presently Z pinches are the most intense laboratory X ray sources (1.8 MJ in 5 ns from a volume 2 mm in diameter and 2 cm tall). Powers in excess of 200 TW have been obtained. This warrants summarizing the present knowledge of physics that governs the behavior of radiating current-carrying plasma in fast Z pinches. This survey covers essentially all aspects of the physics of fast Z pinches: initiation, instabilities of the early stage, magnetic Rayleigh-Taylor instability in the implosion phase, formation of a transient quasi-equilibrium near the stagnation point, and rebound. Considerable attention is paid to the analysis of hydrodynamic instabilities governing the implosion symmetry. Possible ways of mitigating these instabilities are discussed. Non-magnetohydrodynamic effects (anomalous resistivity, generation of particle beams, etc.) are summarized. Various applications of fast Z pinches are briefly described. Scaling laws governing development of more powerful Z pinches are presented. The survey contains 36 figures and more than 300 references.

Positivity of the spherically averaged atomic one-electron density

DEFF Research Database (Denmark)

Fournais, Søren; Hoffmann-Ostenhof, Maria; Hoffmann-Ostenhof, Thomas

2008-01-01

We investigate the positivity of the spherically averaged atomic one-electron density . For a which stems from a physical ground state we prove that for r ≥  0. This article may be reproduced in its entirety for non-commercial purposes.......We investigate the positivity of the spherically averaged atomic one-electron density . For a which stems from a physical ground state we prove that for r ≥  0. This article may be reproduced in its entirety for non-commercial purposes....

Density operators in quantum mechanics

International Nuclear Information System (INIS)

Burzynski, A.

1979-01-01

A brief discussion and resume of density operator formalism in the way it occurs in modern physics (in quantum optics, quantum statistical physics, quantum theory of radiation) is presented. Particularly we emphasize the projection operator method, application of spectral theorems and superoperators formalism in operator Hilbert spaces (Hilbert-Schmidt type). The paper includes an appendix on direct sums and direct products of spaces and operators, and problems of reducibility for operator class by using the projection operators. (author)

Anti-Ferroelectric Ceramics for High Energy Density Capacitors

Directory of Open Access Journals (Sweden)

Aditya Chauhan

2015-11-01

Full Text Available With an ever increasing dependence on electrical energy for powering modern equipment and electronics, research is focused on the development of efficient methods for the generation, storage and distribution of electrical power. In this regard, the development of suitable dielectric based solid-state capacitors will play a key role in revolutionizing modern day electronic and electrical devices. Among the popular dielectric materials, anti-ferroelectrics (AFE display evidence of being a strong contender for future ceramic capacitors. AFE materials possess low dielectric loss, low coercive field, low remnant polarization, high energy density, high material efficiency, and fast discharge rates; all of these characteristics makes AFE materials a lucrative research direction. However, despite the evident advantages, there have only been limited attempts to develop this area. This article attempts to provide a focus to this area by presenting a timely review on the topic, on the relevant scientific advancements that have been made with respect to utilization and development of anti-ferroelectric materials for electric energy storage applications. The article begins with a general introduction discussing the need for high energy density capacitors, the present solutions being used to address this problem, and a brief discussion of various advantages of anti-ferroelectric materials for high energy storage applications. This is followed by a general description of anti-ferroelectricity and important anti-ferroelectric materials. The remainder of the paper is divided into two subsections, the first of which presents various physical routes for enhancing the energy storage density while the latter section describes chemical routes for enhanced storage density. This is followed by conclusions and future prospects and challenges which need to be addressed in this particular field.

Numerical methods on flow instabilities in steam generator

International Nuclear Information System (INIS)

Yoshikawa, Ryuji; Hamada, Hirotsugu; Ohshima, Hiroyuki; Yanagisawa, Hideki

2008-06-01

The phenomenon of two-phase flow instability is important for the design and operation of many industrial systems and equipment, such as steam generators. The designer's job is to predict the threshold of flow instability in order to design around it or compensate for it. So it is essential to understand the physical phenomena governing such instability and to develop computational tools to model the dynamics of boiling systems. In Japan Atomic Energy Agency, investigations on heat transfer characteristics of steam generator are being performed for the development of Sodium-cooled Fast Breeder Reactor. As one part of the research work, the evaluations of two-phase flow instability in the steam generator are being carried out experimentally and numerically. In this report, the numerical methods were studied for two-phase flow instability analysis in steam generator. For numerical simulation purpose, the special algorithm to calculate inlet flow rate iteratively with inlet pressure and outlet pressure as boundary conditions for the density-wave instability analysis was established. There was no need to solve property derivatives and large matrices, so the spurious numerical instabilities caused by discontinuous property derivatives at boiling boundaries were avoided. Large time-step was possible. The flow instability in single heat transfer tube was successfully simulated with homogeneous equilibrium model by using the present algorithm. Then the drift-flux model including the effects of subcooled boiling and two phase slip was adopted to improve the accuracy. The computer code was developed after selecting the correlations of drift velocity and distribution parameter. The capability of drift flux model together with the present algorithm for simulating density-wave instability in single tube was confirmed. (author)

Integrating K-means Clustering with Kernel Density Estimation for the Development of a Conditional Weather Generation Downscaling Model

Science.gov (United States)

Chen, Y.; Ho, C.; Chang, L.

2011-12-01

In previous decades, the climate change caused by global warming increases the occurrence frequency of extreme hydrological events. Water supply shortages caused by extreme events create great challenges for water resource management. To evaluate future climate variations, general circulation models (GCMs) are the most wildly known tools which shows possible weather conditions under pre-defined CO2 emission scenarios announced by IPCC. Because the study area of GCMs is the entire earth, the grid sizes of GCMs are much larger than the basin scale. To overcome the gap, a statistic downscaling technique can transform the regional scale weather factors into basin scale precipitations. The statistic downscaling technique can be divided into three categories include transfer function, weather generator and weather type. The first two categories describe the relationships between the weather factors and precipitations respectively based on deterministic algorithms, such as linear or nonlinear regression and ANN, and stochastic approaches, such as Markov chain theory and statistical distributions. In the weather type, the method has ability to cluster weather factors, which are high dimensional and continuous variables, into weather types, which are limited number of discrete states. In this study, the proposed downscaling model integrates the weather type, using the K-means clustering algorithm, and the weather generator, using the kernel density estimation. The study area is Shihmen basin in northern of Taiwan. In this study, the research process contains two steps, a calibration step and a synthesis step. Three sub-steps were used in the calibration step. First, weather factors, such as pressures, humidities and wind speeds, obtained from NCEP and the precipitations observed from rainfall stations were collected for downscaling. Second, the K-means clustering grouped the weather factors into four weather types. Third, the Markov chain transition matrixes and the

Nonlinear atom optics and bright-gap-soliton generation in finite optical lattices

International Nuclear Information System (INIS)

Carusotto, Iacopo; Embriaco, Davide; La Rocca, Giuseppe C.

2002-01-01

We theoretically investigate the transmission dynamics of coherent matter wave pulses across finite optical lattices in both the linear and the nonlinear regimes. The shape and the intensity of the transmitted pulse are found to strongly depend on the parameters of the incident pulse, in particular its velocity and density: a clear physical picture of the main features observed in the numerical simulations is given in terms of the atomic band dispersion in the periodic potential of the optical lattice. Signatures of nonlinear effects due to the atom-atom interaction are discussed in detail, such as atom-optical limiting and atom-optical bistability. For positive scattering lengths, matter waves propagating close to the top of the valence band are shown to be subject to modulational instability. A scheme for the experimental generation of narrow bright gap solitons from a wide Bose-Einstein condensate is proposed: the modulational instability is seeded starting from the strongly modulated density profile of a standing matter wave and the solitonic nature of the generated pulses is checked from their shape and their collisional properties

Multi-spacecraft observations of small-scale fluctuations in density and fields in plasmaspheric plumes

Directory of Open Access Journals (Sweden)

H. Matsui

2012-03-01

Full Text Available In this event study, small-scale fluctuations in plasmaspheric plumes with time scales of ~10 s to minutes in the spacecraft frame are examined. In one event, plasmaspheric plumes are observed by Cluster, while IMAGE measured density enhancement at a similar location. Fluctuations in density exist in plumes as detected by Cluster and are accompanied by fluctuations in magnetic fields and electric fields. Magnetic fluctuations are transverse and along the direction of the plumes. The E/B ratio is smaller than the Alfvén velocity. Another similar event is briefly presented. We then consider physical properties of the fluctuations. Alfvén mode modulated by the feedback instability is one possibility, although non-local generation is likely. It is hard to show that the fluctuations represent a fast mode. Interchange motion is possible due to the consistency between measurements and expectations. The energy source could be a pressure or density gradient in plasmaspheric plumes. When more events are accumulated so that statistical analysis becomes feasible, this type of study will be useful to understand the time evolution of plumes.

N-particle effective generators of the Poincare group derived from a field theory

International Nuclear Information System (INIS)

Krueger, A.; Gloeckle, W.

1999-01-01

In quantum mechanics the principle of relativity is guaranteed by unitary operators being associated with inhomogeneous Lorentz transformations ensuring that quantum mechanical expectation values remain unchanged. In field theory the ten generators of inhomogeneous Lorentz transformations can be derived from a scalar Lagrangian density describing the physical system of interest. They obey the well known Poincare Lie algebra. For interacting systems some of the generators become operators allowing for particle production or annihilation so that the generators act on the full Fock space. However, given a field theory on the whole Fock space we prove that it is possible to construct generators acting on a subspace with a finite number of particles by one and the same unitary transformation of all generators leaving the Poincare algebra valid. In this manner it is in principle possible to derive a relativistically invariant theory of interacting particles on a Hilbert space with a finite number of particles from a field theoretical Lagrangian. Refs. 3 (author)

Magnetic energy density and plasma energy density in the Venus wake

Science.gov (United States)

Perez De Tejada, H. A.; Durand-Manterola, H. J.; Lundin, R.; Barabash, S.; Zhang, T.; Reyes-Ruiz, M.; Sauvaud, J.

2013-05-01

Magnetic energy density and plasma energy density in the Venus wake H. Pérez-de-Tejada1, H. Durand-Manterola1, R. Lundin2, S. Barabash2, T. L. Zhang3, A. Sauvaud4, M. Reyes-Ruiz5. 1 - Institute of Geophysics, UNAM, México, D. F. 2 - Swedish Institute of Space Physics, Umea, Sweden 3 - Space Research Institute, Graz, Austria 4 - CESR, Toulouse, France 5 - Institute of Astronomy, UNAM, Ensenada, México Measurements conducted in the Venus wake with the magnetometer and the Aspera-4 plasma instrument of the Venus Express spacecraft show that average values of the kinetic energy density of the plasma in that region are comparable to average local values of the magnetic energy density. Observations were carried out in several orbits of the Venus Express near the midnight plane and suggest that the total energy content in the Venus wake is distributed with nearly comparable values between the plasma and the magnetic field. Processes associated with the solar wind erosion of planetary ions from the polar magnetic regions of the ionosphere are involved in the comparable distribution of both energy components.

Physics and Novel Schemes of Laser Radiation Pressure Acceleration for Quasi-monoenergetic Proton Generation

Energy Technology Data Exchange (ETDEWEB)

Liu, Chuan S. [Univ. of Maryland, College Park, MD (United States). Dept. of Physics; Shao, Xi [Univ. of Maryland, College Park, MD (United States)

2016-06-14

The main objective of our work is to provide theoretical basis and modeling support for the design and experimental setup of compact laser proton accelerator to produce high quality proton beams tunable with energy from 50 to 250 MeV using short pulse sub-petawatt laser. We performed theoretical and computational studies of energy scaling and Raleigh--Taylor instability development in laser radiation pressure acceleration (RPA) and developed novel RPA-based schemes to remedy/suppress instabilities for high-quality quasimonoenergetic proton beam generation as we proposed. During the project period, we published nine peer-reviewed journal papers and made twenty conference presentations including six invited talks on our work. The project supported one graduate student who received his PhD degree in physics in 2013 and supported two post-doctoral associates. We also mentored three high school students and one undergraduate student of physics major by inspiring their interests and having them involved in the project.

Validity of physical activity and cardiorespiratory fitness in the Danish cohort 'Diet, Cancer and Health - Next Generations'

DEFF Research Database (Denmark)

Lerche, Lene; Olsen, Anja; Petersen, Kristina Elin Nielsen

2017-01-01

). When validating the questionnaire-derived measures of PA, leisure time physical activity was not correlated with VO2 max. Positive correlations were found for sports overall, but these were only significant for men: total hours per week of sports (r=0.26), MET-hours per week of sports (r=0......Valid assessments of physical activity (PA) and cardiorespiratory fitness (CRF) is essential in epidemiological studies to define dose-response relationship for e.g. formulating thorough recommendations of an appropriate pattern of PA to maintain good health. The aim of this study was to validate...... the Danish step test, the physical activity questionnaire Active-Q and self-rated fitness against directly measured maximal oxygen uptake (VO2 max). A population based subsample (n=125) was included from the 'Diet, Cancer and Health - Next Generations' (DCH-NG) cohort which is under establishment. Validity...

Exoplanet Science in the Classroom: Learning Activities for an Introductory Physics Course

Science.gov (United States)

Della-Rose, Devin; Carlson, Randall; de La Harpe, Kimberly; Novotny, Steven; Polsgrove, Daniel

2018-03-01

Discovery of planets outside our solar system, known as extra-solar planets or exoplanets for short, has been at the forefront of astronomical research for over 25 years. Reports of new discoveries have almost become routine; however, the excitement surrounding them has not. Amazingly, as groundbreaking as exoplanet science is, the basic physics is quite accessible to first-year physics students, as discussed in previous TPT articles. To further illustrate this point, we developed an iOS application that generates synthetic exoplanet data to provide students and teachers with interactive learning activities. Using introductory physics concepts, we demonstrate how to estimate exoplanet mass, radius, and density from the app output. These calculations form the basis for a diverse range of classroom activities. We conclude with a summary of exoplanet science resources for teachers.

Femtosecond laser-plasma interaction with prepulse-generated liquid metal microjets

International Nuclear Information System (INIS)

Uryupina, D. S.; Ivanov, K. A.; Savel'ev, A. B.; Volkov, R. V.; Brantov, A. V.; Bychenkov, V. Yu.; Povarnitsyn, M. E.; Tikhonchuk, V. T.

2012-01-01

Ultrashort laser pulse interaction with a microstructured surface of a melted metal is a promising source of hard x-ray radiation. Microstructuring is achieved by a weak prepulse that produces narrow high-density microjets. As an x-ray source, the interaction of the main laser pulse with such jets is shown to be nearly two orders of magnitude more efficient than the interaction with ordinary metal targets. This paper presents the results of optical and x-ray studies of laser-plasma interaction physics under such conditions supported by numerical simulations of microjet formation and fast-electron generation.

Femtosecond laser-plasma interaction with prepulse-generated liquid metal microjets

Energy Technology Data Exchange (ETDEWEB)

Uryupina, D. S.; Ivanov, K. A.; Savel' ev, A. B.; Volkov, R. V. [Faculty of Physics and International Laser Center of M.V. Lomonosov Moscow State University, 119991 Moscow, Leninskie Gory (Russian Federation); Brantov, A. V.; Bychenkov, V. Yu. [P. N. Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow (Russian Federation); Povarnitsyn, M. E. [Joint Institute for High Temperatures, Russian Academy of Sciences, 125412 Moscow (Russian Federation); Tikhonchuk, V. T. [CELIA, University of Bordeaux - CNRS - CEA, 33405 Talence (France)

2012-01-15

Ultrashort laser pulse interaction with a microstructured surface of a melted metal is a promising source of hard x-ray radiation. Microstructuring is achieved by a weak prepulse that produces narrow high-density microjets. As an x-ray source, the interaction of the main laser pulse with such jets is shown to be nearly two orders of magnitude more efficient than the interaction with ordinary metal targets. This paper presents the results of optical and x-ray studies of laser-plasma interaction physics under such conditions supported by numerical simulations of microjet formation and fast-electron generation.

Relationship of Quantum Entanglement to Density Functional Theory

OpenAIRE

Rajagopal, A. K.; Rendell, R. W.

2005-01-01

The maximum von Neumann entropy principle subject to given constraints of mean values of some physical observables determines the density matrix. Similarly the stationary action principle in the case of time-dependent (dissipative) situations under similar constraints yields the density matrix. The free energy and measures of entanglement are expressed in terms of such a density matrix and thus define respective functionals of the mean values. In the light of several model calculations, it is...

A magnetic suspension system for measuring liquid density

Directory of Open Access Journals (Sweden)

Luz María Centeno González

2013-01-01

Full Text Available Density is a derived quantity of mass and length; it is defined as mass per volume unit and its SI unit is kg/m3. National metrology institutes have been designing and building their own magnetic suspension systems during the last 5 decades for making fluid density measurements; this has allowed them to carry out research into liquids and gases’ physical characteristics. This paper was aimed at designing and developing a magnetic suspension system for a magnetic balance used in determining liquid density to be used in CENAM’s metrology density laboratories.

Molecular dynamics equation designed for realizing arbitrary density: Application to sampling method utilizing the Tsallis generalized distribution

International Nuclear Information System (INIS)

Fukuda, Ikuo; Nakamura, Haruki

2010-01-01

Several molecular dynamics techniques applying the Tsallis generalized distribution are presented. We have developed a deterministic dynamics to generate an arbitrary smooth density function ρ. It creates a measure-preserving flow with respect to the measure ρdω and realizes the density ρ under the assumption of the ergodicity. It can thus be used to investigate physical systems that obey such distribution density. Using this technique, the Tsallis distribution density based on a full energy function form along with the Tsallis index q ≥ 1 can be created. From the fact that an effective support of the Tsallis distribution in the phase space is broad, compared with that of the conventional Boltzmann-Gibbs (BG) distribution, and the fact that the corresponding energy-surface deformation does not change energy minimum points, the dynamics enhances the physical state sampling, in particular for a rugged energy surface spanned by a complicated system. Other feature of the Tsallis distribution is that it provides more degree of the nonlinearity, compared with the case of the BG distribution, in the deterministic dynamics equation, which is very useful to effectively gain the ergodicity of the dynamical system constructed according to the scheme. Combining such methods with the reconstruction technique of the BG distribution, we can obtain the information consistent with the BG ensemble and create the corresponding free energy surface. We demonstrate several sampling results obtained from the systems typical for benchmark tests in MD and from biomolecular systems.

A Safari Through Density Functional Theory

Science.gov (United States)

Dreizler, Reiner M.; Lüdde, Cora S.

Density functional theory is widely used to treat quantum many body problems in many areas of physics and related fields. A brief survey of this method covering foundations, functionals and applications is presented here.

Engineering design of a neutron generator

Energy Technology Data Exchange (ETDEWEB)

Coelho, Daniel M.; Campos, Tarcísio P.R. de, E-mail: dmcoelho.eng@gmail.com, E-mail: tprcampos@pq.cnpq.br [Universidade Federal de Minas Gerais (NRI/UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear. Nucleo de Radiações Ionizantes

2017-07-01

This paper presents an engineering design of a neutron generator (NG). In order to analyze and choose the materials and the appropriate geometry, previous studies of NRI Group (Nucleus for Ionizing Radiation at UFMG - NRI/UFMG) were considered and a model was developed for the simulation of these systems. The efficiency of a neutron generator is measured by the neutron flux. Among the modeling and simulation methods, was employed open software sources for the transmuting cell, aiming to evaluate resonant cavity and for complementary physical analysis. In addition, the titanium target was compared designed based in other studies of NRI Group. Deuterium plasma with a density close to 10{sup 10} particles/cm³, was proposed with a frequency of 0.898 GHz and an approximate wavelength of 110 μm, using a radio frequency antenna up to 2.45 GHz. This compact system includes a hydrogen-isotopes fusor, moderator, reflector and shield. Neutron reflection minimized the neutron escape, increasing the final flux. A insulation material is required to enclose the device. As a conclusion, the investigated nuclear and electromagnetic features of NG have demonstrated that such generator shall have a notable potential for radioisotope generation applied to medical diagnosis. The designs presented will be used to build a 3D model in the NRI laboratory and then a prototype with the selected materials. (author)

Investigation of the density turbulence in ohmic ASDEX plasmas

International Nuclear Information System (INIS)

Dodel, G.; Holtzhauer, E.

1989-01-01

A 119 μm homodyne laser scattering experiment is used on ASDEX to investigate wavenumber and frequency of the density fluctuations occuring in the different operational conditions of the machine. The changes of the density turbulence caused by additional heating are of primary interest with regard to a possible correlation to anomalous transport. Therefore, in the current experiment particular emphasis is placed on these investigations. On the other hand it is the ohmic phase which constitutes the least complicated physical situation in a tokamak and is therefore best suited to reveal the basic physical nature of the density turbulence. In the following we present a summary of our findings in the ohmic phase and make an attempt to compare these findings with what would be expected from the simplest model of density-gradient-driven driftwave turbulence saturated at the mixing-length level. (author) 3 refs., 4 figs

Investigation of the density turbulence in ohmic ASDEX plasmas

Energy Technology Data Exchange (ETDEWEB)

Dodel, G; Holtzhauer, E [Stuttgart Univ. (Germany, F.R.). Inst. fuer Plasmaforschung; Giannone, L.; Niedermeyer, H [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany, F.R.)

1989-01-01

A 119 {mu}m homodyne laser scattering experiment is used on ASDEX to investigate wavenumber and frequency of the density fluctuations occuring in the different operational conditions of the machine. The changes of the density turbulence caused by additional heating are of primary interest with regard to a possible correlation to anomalous transport. Therefore, in the current experiment particular emphasis is placed on these investigations. On the other hand it is the ohmic phase which constitutes the least complicated physical situation in a tokamak and is therefore best suited to reveal the basic physical nature of the density turbulence. In the following we present a summary of our findings in the ohmic phase and make an attempt to compare these findings with what would be expected from the simplest model of density-gradient-driven driftwave turbulence saturated at the mixing-length level. (author) 3 refs., 4 figs.

Differentiability in density-functional theory: Further study of the locality theorem

International Nuclear Information System (INIS)

Lindgren, Ingvar; Salomonson, Sten

2004-01-01

The locality theorem in density-functional theory (DFT) states that the functional derivative of the Hohenberg-Kohn universal functional can be expressed as a local multiplicative potential function, and this is the basis of DFT and of the successful Kohn-Sham model. Nesbet has in several papers [Phys. Rev. A 58, R12 (1998); ibid.65, 010502 (2001); Adv. Quant. Chem, 43, 1 (2003)] claimed that this theorem is in conflict with fundamental quantum physics, and as a consequence that the Hohenberg-Kohn theory cannot be generally valid. We have commented upon these works [Comment, Phys. Rev. A 67, 056501 (2003)] and recently extended the arguments [Adv. Quantum Chem. 43, 95 (2003)]. We have shown that there is no such conflict and that the locality theorem is inherently exact. In the present work we have furthermore verified this numerically by constructing a local Kohn-Sham potential for the 1s2s 3 S state of helium that generates the many-body electron density and shown that the corresponding 2s Kohn-Sham orbital eigenvalue agrees with the ionization energy to nine digits. Similar result is obtained with the Hartree-Fock density. Therefore, in addition to verifying the locality theorem, this result also confirms the so-called ionization-potential theorem

Pulsed x-ray generation from a plasma focus device

International Nuclear Information System (INIS)

Zambra, M; Bruzzone, H; Sidelnikov, Y; Kies, W; Moreno, C; Sylvester, G; Silva, P; Moreno, J; Soto, L

2003-01-01

Dynamical pinches coupled to electrodes like the dense Z-pinch or the dense plasma focus have been intensively studied in the last four decades for their high fusion efficiency and their application potential. Though the expectations of the eighties of the last century, scaling these pinches up to fusion reactors, did not come true, the development of fast and powerful experiments resulted in new insights in pinch physics and paved the way for developing compact dynamical pinches as pulsed neutron and X-radiation sources for many applications. There is a permanent and growing interest in the research community for understanding and determining the generation properties of X-rays, neutrons and charged particles emitted from a high-temperature high-density plasmas, especially in the plasma focus configuration. The Plasma Physics and Plasma Technology Group of the CCHEN has developed the SPEED4 fast-plasma focus device, in collaboration with the Plasma Physics Group of the Dusseldorf University, in order to perform experimental studies such as X-ray and neutron emission, and electron and ion beam characterization (author)

Merger of waste in kaolin panels medium density

International Nuclear Information System (INIS)

Bezerra, A.F.C.; Santana, L.N.L.; Neves, G.A.

2011-01-01

Medium-density panels are molded under pressure and temperature and have physical and mechanical properties similar to those of solid wood. Their composition involves fibers of eucalyptus and pine, but other residues as kaolin waste can be incorporated. The objective was to manufacture medium density panels incorporating kaolin waste and compare the physical, chemical and mechanical properties of these with other commercials. The residue was subjected to the following characterization tests: X-ray diffraction, chemical analysis, differential thermal analysis, thermal gravimetric analysis and size analysis.Through the process of pressing the samples were prepared, they were evaluated for their flexural strength and tensile strength perpendicular to the water absorption / swelling in thickness, density and moisture content. According to the analyzed results, we conclude that samples having the residue had lower levels of swelling, tensile and flexural strength and higher levels of absorption.(author)

Physics at FAIR

International Nuclear Information System (INIS)

Chattopadhyay, Subhasis

2014-01-01

The Facility for Antiproton and Ion Research (FAIR) is under construction at Darmstadt, Germany. It will deliver high intensity beams of ions and antiprotons for experiments in the fields of atomic physics, plasma physics, nuclear physics, hadron physics, nuclear matter physics, material physics and biophysics. One of the scientific pillars of FAIR is the Compressed Baryonic Matter (CBM) experiment which is designed for the study of high density nuclear matter as it exists in the core of neutron stars. In this article the scientific program of FAIR will be reviewed with emphasis on the CBM experiment

Local density approximations for relativistic exchange energies

International Nuclear Information System (INIS)

MacDonald, A.H.

1986-01-01

The use of local density approximations to approximate exchange interactions in relativistic electron systems is reviewed. Particular attention is paid to the physical content of these exchange energies by discussing results for the uniform relativistic electron gas from a new point of view. Work on applying these local density approximations in atoms and solids is reviewed and it is concluded that good accuracy is usually possible provided self-interaction corrections are applied. The local density approximations necessary for spin-polarized relativistic systems are discussed and some new results are presented

Mechanical and physical properties of 2 1/4 Cr--1 Mo steel in support of CRBRP steam generator design

International Nuclear Information System (INIS)

Brinkman, C.R.; Williams, R.K.; Klueh, R.L.; Hebble, T.L.

1975-01-01

Mechanical and physical property tests on annealed 2 1 / 4 Cr-1 Mo steel were conducted in an effort to define behavior in support of the design of the Clinch River Breeder Reactor Plant (CRBRP) steam generator design. Interim empirical expressions and/or data are reported from the results of tensile, creep, fatigue, creep-fatigue, subcritical crack growth, thermal conductivity, thermal diffusivity, and thermal expansion tests and analysis. These expressions cover behavior, where appropriate, over a range of temperatures from 25 to as high as 700 0 C. Comparisons between thermal conductivity and diffusivity values and those found in the American Society of Mechanical Engineers (ASME) Code indicated that the new values were significantly higher than those found presently in the Code. The importance and complexity of obtaining valid mechanical and physical properties for the Clinch River Breeder Reactor Plant (CRBRP) steam generator are discussed. (U.S.)

Density functional theory in quantum chemistry

CERN Document Server

Tsuneda, Takao

2014-01-01

This book examines density functional theory based on the foundation of quantum chemistry. Unconventional in approach, it reviews basic concepts, then describes the physical meanings of state-of-the-art exchange-correlation functionals and their corrections.

High baryon density from relativistic heavy ion collisions

Energy Technology Data Exchange (ETDEWEB)

Pang, Y.; Kahana, S.H. [Brookhaven National Lab., Upton, NY (United States); Schlagel, T.J. [Brookhaven National Lab., Upton, NY (United States)]|[State Univ. of New York, Stony Brook, NY (United States)

1993-10-01

A quantitative model, based on hadronic physics, is developed and applied to heavy ion collisions at BNL-AGS energies. This model is in excellent agreement with observed particle spectra in heavy ion collisions using Si beams, where baryon densities of three and four times the normal nuclear matter density ({rho}{sub 0}) are reached. For Au on Au collisions, the authors predict the formation of matter at very high densities (up to 10 {rho}{sub 0}).

Sensitivity and uncertainty analysis for functionals of the time-dependent nuclide density field

International Nuclear Information System (INIS)

Williams, M.L.; Weisbin, C.R.

1978-04-01

An approach to extend the present ORNL sensitivity program to include functionals of the time-dependent nuclide density field is developed. An adjoint equation for the nuclide field was derived previously by using generalized perturbation theory; the present derivation makes use of a variational principle and results in the same equation. The physical significance of this equation is discussed and compared to that of the time-dependent neutron adjoint equation. Computational requirements for determining sensitivity profiles and uncertainties for functionals of the time-dependent nuclide density vector are developed within the framework of the existing FORSS system; in this way the current capability is significantly extended. The development, testing, and use of an adjoint version of the ORIGEN isotope generation and depletion code are documented. Finally, a sample calculation is given which estimates the uncertainty in the plutonium inventory at shutdown of a PWR due to assumed uncertainties in uranium and plutonium cross sections. 8 figures, 4 tables

Generating a Multiphase Equation of State with Swarm Intelligence

Science.gov (United States)

Cox, Geoffrey

2017-06-01

Hydrocode calculations require knowledge of the variation of pressure of a material with density and temperature, which is given by the equation of state. An accurate model needs to account for discontinuities in energy, density and properties of a material across a phase boundary. When generating a multiphase equation of state the modeller attempts to balance the agreement between the available data for compression, expansion and phase boundary location. However, this can prove difficult because minor adjustments in the equation of state for a single phase can have a large impact on the overall phase diagram. Recently, Cox and Christie described a method for combining statistical-mechanics-based condensed matter physics models with a stochastic analysis technique called particle swarm optimisation. The models produced show good agreement with experiment over a wide range of pressure-temperature space. This talk details the general implementation of this technique, shows example results, and describes the types of analysis that can be performed with this method.

Evaluation of neutron flux density and power density with SPN-detectors and micro calorimeters

International Nuclear Information System (INIS)

Gehre, G.; Rindelhardt, U.; Seidenkranz, T.; Hogel, J.; Jirousek, V.; Vazek, J.

1983-02-01

During investigations with a special equipped fuel assembly in the Rheinsberg nuclear power station the neutron flux and the power density were evaluated from measurements with SPN-detectors and micro calorimeters. The reliability of both detector types, their measurement accuracy under different physical conditions and the usefulness of the developed calculation models are discussed in detail. The thermal flux and the power density evaluated with SPND's agree well with theoretical results. The values obtained through micro calorimeter measurements are systematic lower by about 18%. This deviation is probably a result of differences in the used calculation models. (author)

Increasing Physical Activity during the School Day through Physical Activity Classes: Implications for Physical Educators

Science.gov (United States)

Adkins, Megan; Bice, Matt; Bartee, Todd; Heelan, Kate

2015-01-01

Across the nation schools are adopting health and wellness policies, specifically physical activity (PA) initiatives that aid healthy long-term lifestyles. Interest has been generated about the inclusion of physical activity classes to complement existing physical education classes. Furthermore, discussion has evolved as to if additional…

Gain-switched all-fiber lasers and quasi-continuous wave supercontinuum generation

DEFF Research Database (Denmark)

Larsen, Casper

The extreme broadening phenomenon of supercontinuum (SC) generation in optical fibers is the basis of SC laser sources. These sources have numerous applications in areas, such as spectroscopy and microscopy due to the unique combination of extremely broad spectral bandwidths, high spectral power...... densities, and high spatial coherence. In this work the feasibility of applying gain-switched all-fiber lasers to SC generation is investigated. It is motivated by the simplicity of the architecture and the ability to scale the optical output power of such fiber lasers. The physics of fiber lasers......-switching of fiber lasers with a variety of different configurations are carried out. The peak power, pulse duration, bandwidth, and scaling with repetition rate are thoroughly described. General guidelines are submitted to enable designing of gainswitched fiber lasers with specifically tailored properties...

A generation mechanism for chorus emission

Directory of Open Access Journals (Sweden)

V. Y. Trakhtengerts

1999-01-01

Full Text Available A chorus generation mechanism is discussed, which is based on interrelation of ELF/VLF noise-like and discrete emissions under the cyclotron wave-particle interactions. A natural ELF/VLF noise radiation is excited by the cyclotron instability mechanism in ducts with enhanced cold plasma density or at the plasmapause. This process is accompanied by a step-like deformation of the energetic electron distribution function in the velocity space, which is situated at the boundary between resonant and nonresonant particles. The step leads to the strong phase correlation of interacting particles and waves and to a new backward wave oscillator (BWO regime of wave generation, when an absolute cyclotron instability arises at the central cross section of the geomagnetic trap, in the form of a succession of discrete signals with growing frequency inside each element. The dynamical spectrum of a separate element is formed similar to triggered ELF/VLF emission, when the strong wavelet starts from the equatorial plane. The comparison is given of the model developed using some satellite and ground-based data. In particular, the appearance of separate groups of chorus signals with a duration 2-10 s can be connected with the preliminary stage of the step formation. BWO regime gives a succession period smaller than the bounce period of energetic electrons between the magnetic mirrors and can explain the observed intervals between chorus elements.Key words. Magnetospheric physics (Energetic particles · trapped. Space plasma physics (wave-particle interactions; waves and instabilities

Main physics features driving design concept and physics design constraints

International Nuclear Information System (INIS)

Fujisawa, Noboru; Sugihara, Masayoshi; Yamamoto, Shin

1987-07-01

Major physics design philosophies are described, which are essential bases for a plasma design and may have significant impacts on a reactor design concept. Those design philosophies are classified into two groups, physics design drivers and physics design constraints. The design drivers are featured by the fact that a designer is free to choose and the choice may be guided by his opinion, such as ignition, a pulse length, an operation scenario, etc.. The design constraints may follow a physical law, such as plasma confinement, β-limit, density limit, and so on. (author)

Analysis of bone mellow density in adults of domestic local area using multi-detector computed tomography: Focus on correlation about eating habits, lifestyle, physical features and social characteristics

International Nuclear Information System (INIS)

Lee, Tae Hui; Kim, Tae Hyung; So, Woon Young; Lim, Hei Gyeom; Lim, Cheong Hwan; Park, Myeong Hwan; Cheon, Myung Ki

2016-01-01

This study analyzed the correlation between BMD (bone mineral density) value calculated in the MDCT(multidetector computed tomography) and lifestyle, physical features and social characteristics. From July 15 2015 to June 6 2016, we converted from HU (hounsfield unit) value measured by using MDCT to T-score for BMD of 141 patients (male: 63, female: 78) in W medical center. We measured the 2nd, 3rd and 4th lumbar spine and analyzed the correlation between gender differences in BMD and lifestyle, physical features and social characteristics. Statistical significance was validated using independent sample T test with one way Anova. Gender BMD was confirmed that a statistically significant difference (p<0.05). BMD values decreased with increasing age but for the statistically men, there was no significant difference from 20s to 50s, it only showed a significant difference in 20s and 60s (p<0.001). For the statistically women, there was no significant difference from 20s to 40s. but since 50s BMD was decreased rapidly, which showed a significant difference(p<0.001). women showed significant differences for the menstruation and menopause, childbirth, alcohol, cereals and greasy food in bone mineral density (p<0.05) but there were no significant differences in men. The bone mineral density values calculated by the MDCT and lifestyle, physical features and social characteristics correlation analysis method is considered to be used as a basis for estimating the state in BMD and osteoporosis management

Analysis of bone mellow density in adults of domestic local area using multi-detector computed tomography: Focus on correlation about eating habits, lifestyle, physical features and social characteristics

Energy Technology Data Exchange (ETDEWEB)

Lee, Tae Hui [Wonju Medical Center, Wonju (Korea, Republic of); Kim, Tae Hyung; So, Woon Young; Lim, Hei Gyeom [Kangwon National University Graduate School, Wonju (Korea, Republic of); Lim, Cheong Hwan [Hanseo University, Seosan (Korea, Republic of); Park, Myeong Hwan [Daegu Health College, Daegu (Korea, Republic of); Cheon, Myung Ki [Soongsil University, Seoul (Korea, Republic of)

2016-12-15

This study analyzed the correlation between BMD (bone mineral density) value calculated in the MDCT(multidetector computed tomography) and lifestyle, physical features and social characteristics. From July 15 2015 to June 6 2016, we converted from HU (hounsfield unit) value measured by using MDCT to T-score for BMD of 141 patients (male: 63, female: 78) in W medical center. We measured the 2nd, 3rd and 4th lumbar spine and analyzed the correlation between gender differences in BMD and lifestyle, physical features and social characteristics. Statistical significance was validated using independent sample T test with one way Anova. Gender BMD was confirmed that a statistically significant difference (p<0.05). BMD values decreased with increasing age but for the statistically men, there was no significant difference from 20s to 50s, it only showed a significant difference in 20s and 60s (p<0.001). For the statistically women, there was no significant difference from 20s to 40s. but since 50s BMD was decreased rapidly, which showed a significant difference(p<0.001). women showed significant differences for the menstruation and menopause, childbirth, alcohol, cereals and greasy food in bone mineral density (p<0.05) but there were no significant differences in men. The bone mineral density values calculated by the MDCT and lifestyle, physical features and social characteristics correlation analysis method is considered to be used as a basis for estimating the state in BMD and osteoporosis management.

BOOK REVIEW: Quantum Generations. A history of physics in the twentieth century

Science.gov (United States)

Brown, Neil

2000-03-01

project ever undertaken, is discussed. Since World War II support from governments for physics has increased enormously, but the fortunes of many physicists have remained entwined with the military establishment and many others now work within megaprojects such as CERN. At the end of the century the numbers of physicists and of papers published have grown a hundred-fold, and funding by an even larger factor. Other aspects have changed less. Physics is still male-dominated and largely a North American and European enterprise. Latterly there has been some reduction in support. Physics, along with the rest of science, has also been under attack for the problems it has created. The beginning of the twenty-first century promises to be as interesting for physics as recent decades have been. Comparison with the other recent work in this field, the three-volume Twentieth Century Physics edited by Laurie Brown, Abraham Pais and Brian Pippard (Institute of Physics Publishing and American Institute of Physics Press, 1995), is unavoidable. They fill different niches. Twentieth Century Physics is a massive and expensive work by some 30 leading physicists, destined mainly for the shelves of academic libraries. Quantum Generations is a book by a professional historian covering much of the same physics, albeit more briefly, but written with a broader sweep that takes in more of the political and cultural milieu within which the physicists worked. References are given sparingly so as not to break up the text, but there are suggestions for further reading for each chapter, and there is an extensive bibliography. It is not a book for those with no background at all in physics - there are too many equations of nuclear reactions for that, and in any case such a book would be a superficial thing. Even many physicists will find some of the more esoteric ideas, such as the grand unified theories and superstring theory, heavy going. It is, however, accessible to a wide readership, and a book that

Dosimetric Properties of Plasma Density Effects on Laser-Accelerated VHEE Beams Using a Sharp Density-Transition Scheme

Energy Technology Data Exchange (ETDEWEB)

Yoo, Seung Hoon; Cho, Sungho; Kim, Eun Ho; Park, Jeong Hoon; Jung, Won-Gyun; Kim, Geun Beom; Kim, Kum Bae [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Min, Byung Jun [Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Kim, Jaehoon [Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Jeong, Hojin [Gyeongsang National University Hospital, Jinju (Korea, Republic of); Lee, Kitae [Korea Atomic Energy Research Institute, Deajeon (Korea, Republic of); Park, Sung Yong [Karmanos Cancer Institute, Michigan (United States)

2017-01-15

In this paper, the effects of the plasma density on laser-accelerated electron beams for radiation therapy with a sharp density transition are investigated. In the sharp density-transition scheme for electron injection, the crucial issue is finding the optimum density conditions under which electrons injected only during the first period of the laser wake wave are accelerated further. In this paper, we report particle-in-cell simulation results for the effects of both the scale length and the density transition ratio on the generation of a quasi-mono-energetic electron bunch. The effects of both the transverse parabolic channel and the plasma length on the electron-beam's quality are investigated. Also, we show the experimental results for the feasibility of a sharp density-transition structure. The dosimetric properties of these very high-energy electron beams are calculated using Monte Carlo simulations.

A performance analysis for MHD power cycles operating at maximum power density

International Nuclear Information System (INIS)

Sahin, Bahri; Kodal, Ali; Yavuz, Hasbi

1996-01-01

An analysis of the thermal efficiency of a magnetohydrodynamic (MHD) power cycle at maximum power density for a constant velocity type MHD generator has been carried out. The irreversibilities at the compressor and the MHD generator are taken into account. The results obtained from power density analysis were compared with those of maximum power analysis. It is shown that by using the power density criteria the MHD cycle efficiency can be increased effectively. (author)

Density of Threatened and Endangered Species

Data.gov (United States)

California Natural Resource Agency — A compiled density of threatened and endangered species built around 2000m wide hexagonal cells. The dataset was created by generating a blank hex grid, intersecting...

Mechanism of the free charge carrier generation in the dielectric breakdown

Science.gov (United States)

Rahim, N. A. A.; Ranom, R.; Zainuddin, H.

2017-12-01

Many studies have been conducted to investigate the effect of environmental, mechanical and electrical stresses on insulator. However, studies on physical process of discharge phenomenon, leading to the breakdown of the insulator surface are lacking and difficult to comprehend. Therefore, this paper analysed charge carrier generation mechanism that can cause free charge carrier generation, leading toward surface discharge development. Besides, this paper developed a model of surface discharge based on the charge generation mechanism on the outdoor insulator. Nernst’s Planck theory was used in order to model the behaviour of the charge carriers while Poisson’s equation was used to determine the distribution of electric field on insulator surface. In the modelling of surface discharge on the outdoor insulator, electric field dependent molecular ionization was used as the charge generation mechanism. A mathematical model of the surface discharge was solved using method of line technique (MOL). The result from the mathematical model showed that the behaviour of net space charge density was correlated with the electric field distribution.

Neutron generator for BNCT based on high current ECR ion source with gyrotron plasma heating.

Science.gov (United States)

Skalyga, V; Izotov, I; Golubev, S; Razin, S; Sidorov, A; Maslennikova, A; Volovecky, A; Kalvas, T; Koivisto, H; Tarvainen, O

2015-12-01

BNCT development nowadays is constrained by a progress in neutron sources design. Creation of a cheap and compact intense neutron source would significantly simplify trial treatments avoiding use of expensive and complicated nuclear reactors and accelerators. D-D or D-T neutron generator is one of alternative types of such sources for. A so-called high current quasi-gasdynamic ECR ion source with plasma heating by millimeter wave gyrotron radiation is suggested to be used in a scheme of D-D neutron generator in the present work. Ion source of that type was developed in the Institute of Applied Physics of Russian Academy of Sciences (Nizhny Novgorod, Russia). It can produce deuteron ion beams with current density up to 700-800 mA/cm(2). Generation of the neutron flux with density at the level of 7-8·10(10) s(-1) cm(-2) at the target surface could be obtained in case of TiD2 target bombardment with deuteron beam accelerated to 100 keV. Estimations show that it is enough for formation of epithermal neutron flux with density higher than 10(9) s(-1) cm(-2) suitable for BNCT. Important advantage of described approach is absence of Tritium in the scheme. First experiments performed in pulsed regime with 300 mA, 45 kV deuteron beam directed to D2O target demonstrated 10(9) s(-1) neutron flux. This value corresponds to theoretical estimations and proofs prospects of neutron generator development based on high current quasi-gasdynamic ECR ion source. Copyright © 2015 Elsevier Ltd. All rights reserved.

The effect of immigration status on physics identity and physical science career intentions

Science.gov (United States)

Lung, Florin; Potvin, Geoff; Sonnert, Gerhard; Sadler, Philip M.

2012-02-01

Using data collected from a nationally-representative sample of first-year college students, we examine how students' identity development as physics persons and their likelihood to pursue a career in physical science is predicted by differing immigrant experiences. We consider broad factors having a social, economic, or cultural nature as covariates in a propensity score model that assesses differences due to immigrant generation. Our results show that, when controlling for such factors as race/ethnicity, socio-economic status, and gender, students' physics identities and the likelihood of choosing a career in physical science are significantly higher amongst first generation students than second generation (or later) students. We conclude that physical science as a career option can be influenced by the experiences of being an immigrant and through the relationship between origin and host culture.

Density Fluctuations in a Polar Coronal Hole

Science.gov (United States)

Hahn, Michael; D’Huys, Elke; Savin, Daniel Wolf

2018-06-01

We have measured the root-mean-square (rms) amplitude of intensity fluctuations, ΔI, in plume and interplume regions of a polar coronal hole. These intensity fluctuations correspond to density fluctuations. Using data from the Sun Watcher using the Active Pixel System detector and Image Processing on the Project for Onboard Autonomy (Proba2), our results extend up to a height of about 1.35 R ⊙. One advantage of the rms analysis is that it does not rely on a detailed evaluation of the power spectrum, which is limited by noise levels to low heights in the corona. The rms approach can be performed up to larger heights where the noise level is greater, provided that the noise itself can be quantified. At low heights, both the absolute ΔI, and the amplitude relative to the mean intensity, ΔI/I, decrease with height. However, starting at about 1.2 R ⊙, ΔI/I increases, reaching 20%–40% by 1.35 R ⊙. This corresponds to density fluctuations of Δn e/n e ≈ 10%–20%. The increasing relative amplitude implies that the density fluctuations are generated in the corona itself. One possibility is that the density fluctuations are generated by an instability of Alfvén waves. This generation mechanism is consistent with some theoretical models and with observations of Alfvén wave amplitudes in coronal holes. Although we find that the energy of the observed density fluctuations is small, these fluctuations are likely to play an important indirect role in coronal heating by promoting the reflection of Alfvén waves and driving turbulence.

Distributed Noise Generation for Density Estimation Based Clustering without Trusted Third Party

Science.gov (United States)

Su, Chunhua; Bao, Feng; Zhou, Jianying; Takagi, Tsuyoshi; Sakurai, Kouichi

The rapid growth of the Internet provides people with tremendous opportunities for data collection, knowledge discovery and cooperative computation. However, it also brings the problem of sensitive information leakage. Both individuals and enterprises may suffer from the massive data collection and the information retrieval by distrusted parties. In this paper, we propose a privacy-preserving protocol for the distributed kernel density estimation-based clustering. Our scheme applies random data perturbation (RDP) technique and the verifiable secret sharing to solve the security problem of distributed kernel density estimation in [4] which assumed a mediate party to help in the computation.

Tailored motivational message generation: A model and practical framework for real-time physical activity coaching.

Science.gov (United States)

Op den Akker, Harm; Cabrita, Miriam; Op den Akker, Rieks; Jones, Valerie M; Hermens, Hermie J

2015-06-01

This paper presents a comprehensive and practical framework for automatic generation of real-time tailored messages in behavior change applications. Basic aspects of motivational messages are time, intention, content and presentation. Tailoring of messages to the individual user may involve all aspects of communication. A linear modular system is presented for generating such messages. It is explained how properties of user and context are taken into account in each of the modules of the system and how they affect the linguistic presentation of the generated messages. The model of motivational messages presented is based on an analysis of existing literature as well as the analysis of a corpus of motivational messages used in previous studies. The model extends existing 'ontology-based' approaches to message generation for real-time coaching systems found in the literature. Practical examples are given on how simple tailoring rules can be implemented throughout the various stages of the framework. Such examples can guide further research by clarifying what it means to use e.g. user targeting to tailor a message. As primary example we look at the issue of promoting daily physical activity. Future work is pointed out in applying the present model and framework, defining efficient ways of evaluating individual tailoring components, and improving effectiveness through the creation of accurate and complete user- and context models. Copyright © 2015 Elsevier Inc. All rights reserved.

Passive acoustic measurement of bedload grain size distribution using self-generated noise

Directory of Open Access Journals (Sweden)

T. Petrut

2018-01-01

Full Text Available Monitoring sediment transport processes in rivers is of particular interest to engineers and scientists to assess the stability of rivers and hydraulic structures. Various methods for sediment transport process description were proposed using conventional or surrogate measurement techniques. This paper addresses the topic of the passive acoustic monitoring of bedload transport in rivers and especially the estimation of the bedload grain size distribution from self-generated noise. It discusses the feasibility of linking the acoustic signal spectrum shape to bedload grain sizes involved in elastic impacts with the river bed treated as a massive slab. Bedload grain size distribution is estimated by a regularized algebraic inversion scheme fed with the power spectrum density of river noise estimated from one hydrophone. The inversion methodology relies upon a physical model that predicts the acoustic field generated by the collision between rigid bodies. Here we proposed an analytic model of the acoustic energy spectrum generated by the impacts between a sphere and a slab. The proposed model computes the power spectral density of bedload noise using a linear system of analytic energy spectra weighted by the grain size distribution. The algebraic system of equations is then solved by least square optimization and solution regularization methods. The result of inversion leads directly to the estimation of the bedload grain size distribution. The inversion method was applied to real acoustic data from passive acoustics experiments realized on the Isère River, in France. The inversion of in situ measured spectra reveals good estimations of grain size distribution, fairly close to what was estimated by physical sampling instruments. These results illustrate the potential of the hydrophone technique to be used as a standalone method that could ensure high spatial and temporal resolution measurements for sediment transport in rivers.

Passive acoustic measurement of bedload grain size distribution using self-generated noise

Science.gov (United States)

Petrut, Teodor; Geay, Thomas; Gervaise, Cédric; Belleudy, Philippe; Zanker, Sebastien

2018-01-01

Monitoring sediment transport processes in rivers is of particular interest to engineers and scientists to assess the stability of rivers and hydraulic structures. Various methods for sediment transport process description were proposed using conventional or surrogate measurement techniques. This paper addresses the topic of the passive acoustic monitoring of bedload transport in rivers and especially the estimation of the bedload grain size distribution from self-generated noise. It discusses the feasibility of linking the acoustic signal spectrum shape to bedload grain sizes involved in elastic impacts with the river bed treated as a massive slab. Bedload grain size distribution is estimated by a regularized algebraic inversion scheme fed with the power spectrum density of river noise estimated from one hydrophone. The inversion methodology relies upon a physical model that predicts the acoustic field generated by the collision between rigid bodies. Here we proposed an analytic model of the acoustic energy spectrum generated by the impacts between a sphere and a slab. The proposed model computes the power spectral density of bedload noise using a linear system of analytic energy spectra weighted by the grain size distribution. The algebraic system of equations is then solved by least square optimization and solution regularization methods. The result of inversion leads directly to the estimation of the bedload grain size distribution. The inversion method was applied to real acoustic data from passive acoustics experiments realized on the Isère River, in France. The inversion of in situ measured spectra reveals good estimations of grain size distribution, fairly close to what was estimated by physical sampling instruments. These results illustrate the potential of the hydrophone technique to be used as a standalone method that could ensure high spatial and temporal resolution measurements for sediment transport in rivers.

High Energy Density Laboratory Astrophysics

CERN Document Server

Lebedev, Sergey V

2007-01-01

During the past decade, research teams around the world have developed astrophysics-relevant research utilizing high energy-density facilities such as intense lasers and z-pinches. Every two years, at the International conference on High Energy Density Laboratory Astrophysics, scientists interested in this emerging field discuss the progress in topics covering: - Stellar evolution, stellar envelopes, opacities, radiation transport - Planetary Interiors, high-pressure EOS, dense plasma atomic physics - Supernovae, gamma-ray bursts, exploding systems, strong shocks, turbulent mixing - Supernova remnants, shock processing, radiative shocks - Astrophysical jets, high-Mach-number flows, magnetized radiative jets, magnetic reconnection - Compact object accretion disks, x-ray photoionized plasmas - Ultrastrong fields, particle acceleration, collisionless shocks. These proceedings cover many of the invited and contributed papers presented at the 6th International Conference on High Energy Density Laboratory Astrophys...

Enthalpy generation from mixing in hohlraum-driven targets

Science.gov (United States)

Amendt, Peter; Milovich, Jose

2016-10-01

The increase in enthalpy from the physical mixing of two initially separated materials is analytically estimated and applied to ICF implosions and gas-filled hohlraums. Pressure and temperature gradients across a classical interface are shown to be the origin of enthalpy generation from mixing. The amount of enthalpy generation is estimated to be on the order of 100 Joules for a 10 micron-scale annular mixing layer between the solid deuterium-tritium fuel and the undoped high-density carbon ablator of a NIF-scale implosion. A potential resonance is found between the mixing layer thickness and gravitational (Cs2/ g) and temperature-gradient scale lengths, leading to elevated enthalpy generation. These results suggest that if mixing occurs in current capsule designs for the National Ignition Facility, the ignition margin may be appreciably eroded by the associated enthalpy of mixing. The degree of enthalpy generation from mixing of high- Z hohlraum wall material and low- Z gas fills is estimated to be on the order of 100 kJ or more for recent NIF-scale hohlraum experiments, which is consistent with the inferred missing energy based on observed delays in capsule implosion times. Work performed under the auspices of Lawrence Livermore National Security, LLC (LLNS) under Contract No. DE-AC52-07NA27344.

Magnetohydrodynamic power generation

International Nuclear Information System (INIS)

Sheindlin, A.E.; Jackson, W.D.; Brzozowski, W.S.; Rietjens, L.H.Th.

1979-01-01

The paper describes research and development in the field of magnetohydrodynamic power generation technology, based on discussions held in the Joint IAEA/UNESCO International Liaison Group on MHD electrical power generation. Research and development programmes on open cycle, closed cycle plasma and liquid-metal MHD are described. Open cycle MHD has now entered the engineering development stage. The paper reviews the results of cycle analyses and economic and environmental evaluations: substantial agreement has been reached on the expected overall performance and necessary component specifications. The achievement in the Soviet Union on the U-25 MHD pilot plant in obtaining full rated electrical power of 20.4 MW is described, as well as long duration testing of the integrated operation of MHD components. Work in the United States on coal-fired MHD generators has shown that, with slagging of the walls, a run time of about one hundred hours at the current density and electric field of a commercial MHD generator has been achieved. Progress obtained in closed cycle plasma and liquid metal MHD is reviewed. Electrical power densities of up to 140 MWe/m 3 and an enthalpy extraction as high as 24 per cent have been achieved in noble gas MHD generator experiments. (Auth.)

Photoionization and High Density Gas

Science.gov (United States)

Kallman, T.; Bautista, M.; White, Nicholas E. (Technical Monitor)

2002-01-01

We present results of calculations using the XSTAR version 2 computer code. This code is loosely based on the XSTAR v.1 code which has been available for public use for some time. However it represents an improvement and update in several major respects, including atomic data, code structure, user interface, and improved physical description of ionization/excitation. In particular, it now is applicable to high density situations in which significant excited atomic level populations are likely to occur. We describe the computational techniques and assumptions, and present sample runs with particular emphasis on high density situations.

Physical and Chemical Properties of Coal Bottom Ash (CBA) from Tanjung Bin Power Plant

Science.gov (United States)

Izzati Raihan Ramzi, Nurul; Shahidan, Shahiron; Zulkhairi Maarof, Mohamad; Ali, Noorwirdawati

2016-11-01

The objective of this study is to determine the physical and chemical characteristics of Coal Bottom Ash (CBA) obtained from Tanjung Bin Power Plant Station and compare them with the characteristics of natural river sand (as a replacement of fine aggregates). Bottom ash is the by-product of coal combustion during the electricity generating process. However, excess bottom ash production due to the high production of electricity in Malaysia has caused several environmental problems. Therefore, several tests have been conducted in order to determine the physical and chemical properties of bottom ash such as specific gravity, density, particle size distribution, Scanning Electron Microscopic (SEM) and X- Ray Fluorescence (XRF) in the attempt to produce sustainable material from waste. The results indicated that the natural fine aggregate and coal bottom ash have very different physical and chemical properties. Bottom ash was classified as Class C ash. The porous structure, angular and rough texture of bottom ash affected its specific gravity and particle density. From the tests, it was found that bottom ash is recommended to be used in concrete as a replacement for fine aggregates.

Generation of Ta ions at high laser-power densities

Czech Academy of Sciences Publication Activity Database

Láska, Leoš; Jungwirth, Karel; Králiková, Božena; Krása, Josef; Pfeifer, Miroslav; Rohlena, Karel; Skála, Jiří; Ullschmied, Jiří; Badziak, J.; Parys, P.; Wolowski, J.; Woryna, E.

2002-01-01

Roč. 52, Suppl. D (2002), s. D283-D291 ISSN 0011-4626. [Plasma Physics and Technology. Prague, 10.06.2002-13.06.2002] Institutional research plan: CEZ:AV0Z1010921 Keywords : laser produced plasma * multiple charged Ta ions Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.311, year: 2002

Quantum Chromodynamics and nuclear physics at extreme energy density

International Nuclear Information System (INIS)

Mueller, B.

1993-01-01

This report discusses research in the following topics: Hadron structure physics; relativistic heavy ion collisions; finite- temperature QCD; real-time lattice gauge theory; and studies in quantum field theory

Seismic-Scale Rock Physics of Methane Hydrate

Energy Technology Data Exchange (ETDEWEB)

Amos Nur

2009-01-08

We quantify natural methane hydrate reservoirs by generating synthetic seismic traces and comparing them to real seismic data: if the synthetic matches the observed data, then the reservoir properties and conditions used in synthetic modeling might be the same as the actual, in-situ reservoir conditions. This approach is model-based: it uses rock physics equations that link the porosity and mineralogy of the host sediment, pressure, and hydrate saturation, and the resulting elastic-wave velocity and density. One result of such seismic forward modeling is a catalogue of seismic reflections of methane hydrate which can serve as a field guide to hydrate identification from real seismic data. We verify this approach using field data from known hydrate deposits.

Nuclear interaction potential in a folded-Yukawa model with diffuse densities

International Nuclear Information System (INIS)

Randrup, J.

1975-09-01

The folded-Yukawa model for the nuclear interaction potential is generalized to diffuse density distributions which are generated by folding a Yukawa function into sharp generating distributions. The effect of a finite density diffuseness or of a finite interaction range is studied. The Proximity Formula corresponding to the generalized model is derived and numerical comparison is made with the exact results. (8 figures)

Conditional density matrix: systems and subsystems in quantum mechanics

International Nuclear Information System (INIS)

Belokurov, V.V.; Khrustalev, O.A.; Sadovnichij, V.A.; Timofeevskaya, O.D.

2003-01-01

A new quantum mechanical notion - Conditional Density Matrix - is discussed and is applied to describe some physical processes. This notion is a natural generalization of von Neumann density matrix for such processes as divisions of quantum systems into subsystems and reunifications of subsystems into new joint systems. Conditional Density Matrix assigns a quantum state to a subsystem of a composite system on condition that another part of the composite system is in some pure state

Instantons: Dynamical mass generation, chiral ward identities and the topological charge correlation function

International Nuclear Information System (INIS)

McDougall, N.A.

1983-01-01

When dynamical mass generation resulting from the breakdown of chiral symmetry is taken into account, instanton dynamics treated within the dilute gas approximation may satisfy the constraints on the quark condensates and the topological charge correlation function derived by Crewther from an analysis of the chiral Ward identities assuming the absence of a physical axial U(1) Goldstone boson. From a consideration of the contribution of the eta' to the topological charge correlation function, a relationship is derived in which msub(eta') 2 fsub(eta') 2 is proportional to the vacuum energy density. (orig.)

Gap and density theorems

CERN Document Server

Levinson, N

1940-01-01

A typical gap theorem of the type discussed in the book deals with a set of exponential functions { \\{e^{{{i\\lambda}_n} x}\\} } on an interval of the real line and explores the conditions under which this set generates the entire L_2 space on this interval. A typical gap theorem deals with functions f on the real line such that many Fourier coefficients of f vanish. The main goal of this book is to investigate relations between density and gap theorems and to study various cases where these theorems hold. The author also shows that density- and gap-type theorems are related to various propertie

Cross-Layer Framework for Fine-Grained Channel Access in Next Generation High-Density WiFi Networks

Institute of Scientific and Technical Information of China (English)

ZHAO Haitao; ZHANG Shaojie; Emiliano Garcia-Palacios

2016-01-01

Densely deployed WiFi networks will play a crucial role in providing the capacity for next generation mobile internet.However,due to increasing interference,overlapped channels in WiFi networks and throughput efficiency degradation,densely deployed WiFi networks is not a guarantee to obtain higher throughput.An emergent challenge is how to efficiently utilize scarce spectrum resources,by matching physical layer resources to traffic demand.In this aspect,access control allocation strategies play a pivotal role but remain too coarse-grained.As a solution,this research proposes a flexible framework for fine-grained channel width adaptation and multi-channel access in WiFi networks.This approach,named SFCA (Subcarrier Fine-grained Channel Access),adopts DOFDM (Discontinuous Orthogonal Frequency Division Multiplexing) at the PHY layer.It allocates the frequency resource with a subcarrier granularity,which facilitates the channel width adaptation for multi-channel access and thus brings more flexibility and higher frequency efficiency.The MAC layer uses a frequencytime domain backoff scheme,which combines the popular time-domain BEB scheme with a frequency-domain backoff to decrease access collision,resulting in higher access probability for the contending nodes.SFCA is compared with FICA (an established access scheme) showing significant outperformance.Finally we present results for next generation 802.11 ac WiFi networks.

Density functional theory of nuclei

International Nuclear Information System (INIS)

Terasaki, Jun

2008-01-01

The density functional theory of nuclei has come to draw attention of scientists in the field of nuclear structure because the theory is expected to provide reliable numerical data in wide range on the nuclear chart. This article is organized to present an overview of the theory to the people engaged in the theory of other fields as well as those people in the nuclear physics experiments. At first, the outline of the density functional theory widely used in the electronic systems (condensed matter, atoms, and molecules) was described starting from the Kohn-Sham equation derived on the variational principle. Then the theory used in the field of nuclear physics was presented. Hartree-Fock and Hartree-Fock-Bogolyubov approximation by using Skyrme interaction was explained. Comparison of the results of calculations and experiments of binding energies and ground state mean square charge radii of some magic number nuclei were shown. The similarity and dissimilarity between the two streams were summarized. Finally the activities of the international project of Universal Nuclear Energy Density Functional (UNEDF) which was started recently lead by US scientist was reported. This project is programmed for five years. One of the applications of the project is the calculation of the neutron capture cross section of nuclei on the r-process, which is absolutely necessary for the nucleosynthesis research. (S. Funahashi)

The calculation of electron density of the non-ideal argon plasma

International Nuclear Information System (INIS)

Jiang Ming; Cheng Xinlu; Yang Xiangdong

2004-01-01

By the screened hydrogenic model, the paper calculates the electron densities of shock-generated argon plasma with temperature T∼2.0 eV and density of plasma ρ∼0.01 g/cm 3 -0.49 g/cm 3 , and studies the influence on electron density caused by interparticle interaction at the different temperature and density of plasma. (author)

Effects of the current boundary conditions at the plasma-gun gap on density in SSPX

Science.gov (United States)

Kolesnikov, Roman; Lodestro, L. L.; Meyer, W. H.

2012-10-01

The Sustained Spheromak Physics Experiment (SSPX) was a toroidal magnetic-confinement device without toroidal magnetic-field coils or a central transformer but which generated core-plasma currents by dynamo processes driven by coaxial plasma-gun injection into a flux-conserving vessel. Record electron temperatures in a spheromak (Te˜500eV) were achieved, and final results of the SSPX program were reported in [1]. Plasma density, which depended strongly on wall conditions, was an important parameter in SSPX. It was observed that density rises with Igun and that confinement improved as the density was lowered. Shortly after the last experiments, a new feature was added to the Corsica code's solver used to reconstruct SSPX equilibria. Motivated by n=0 fields observed in NIMROD simulations of SSPX, an insulating boundary condition was implemented at the plasma-gun gap. Using this option we will perform new reconstructions of SSPX equilibria and look for correlations between the location of the separatrix (which moves up the gun wall and onto the insulating gap as Igun increases) and plasma density and magnetic-flux amplification [2].[4pt] [1] H. S. McLean, APS, DPP, Dallas, TX, 2008.[0pt] [2] E. B. Hooper et al., Nucl. Fusion 47, 1064 (2007).

Surface runoff generation in a small watershed covered by sugarcane and riparian forest

Directory of Open Access Journals (Sweden)

Rafael Pires Fernandes

2013-12-01

Full Text Available Since an understanding of how runoff is generated is of great importance to soil conservation, to water availability and to the management of a watershed, the objective of this study was to understand the generation of surface runoff in a watershed covered by sugarcane and riparian forest. Nine surface runoff plots were set up, evenly distributed on the lower, middle and upper slopes. The lower portion was covered by riparian forest. We showed that the average surface runoff coefficient along the slope in the present study was higher than in other studies under different land uses. Furthermore, the surface runoff was higher under sugarcane compared to the riparian forest, especially after sugarcane harvesting. Besides land cover, other factors such as the characteristics of rainfall events, relief and physical soil characteristics such as soil bulk density and saturated hydraulic conductivity influenced the surface runoff generation.

DEVELOPMENT OF A METHODOLOGY TO ASSESS PROLIFERATION RESISTANCE AND PHYSICAL PROTECTION FOR GENERATION IV SYSTEMS

International Nuclear Information System (INIS)

Nishimura, R.; Bari, R.; Peterson, P.; Roglans-Ribas, J.; Kalenchuk, D.

2004-01-01

Enhanced proliferation resistance and physical protection (PR and PP) is one of the technology goals for advanced nuclear concepts, such as Generation IV systems. Under the auspices of the Generation IV International Forum, the Office of Nuclear Energy, Science and Technology of the U.S. DOE, the Office of Nonproliferation Policy of the National Nuclear Security Administration, and participating organizations from six other countries are sponsoring an international working group to develop an evaluation methodology for PR and PP. This methodology will permit an objective PR and PP comparison between alternative nuclear systems (e.g., different reactor types or fuel cycles) and support design optimization to enhance robustness against proliferation, theft and sabotage. The paper summarizes the proposed assessment methodology including the assessment framework, measures used to express the PR and PP characteristics of the system, threat definition, system element and target identification, pathway identification and analysis, and estimation of the measures

Generating an AC amplitude magnetic flux density value up to 150 μT at a frequency up to 100 kHz

Science.gov (United States)

Ulvr, Michal; Polonský, Jakub

2017-05-01

AC magnetic field analyzers with a triaxial coil probe are widely used by health and safety professionals, in manufacturing, and in service industries. For traceable calibration of these analyzers, it is important to be able to generate a stable, homogeneous reference AC magnetic flux density (MFD). In this paper, the generating of AC amplitude MFD value of 150 μT by single-layer Helmholtz type solenoid, described in previous work, was expanded up to a frequency of 100 kHz using the effect of serial resonance. A programmable capacitor array has been developed with a range of adjustable values from 50 pF to 51225 pF. In addition, the multi-layer search coil with a nominal area turns value of 1.3m2, used for adjusting AC MFD in the solenoid, has been modified by a transimpedance amplifier for use in a wider frequency range than up to 3 kHz. The possibility of using the programmable capacitor array up to 150 kHz has also been tested. An AC amplitude MFD value of 150 μT can be generated with expanded uncertainty better than 0.6% up to 100 kHz.

Beam-generated plasmas for processing applications

Science.gov (United States)

Meger, R. A.; Blackwell, D. D.; Fernsler, R. F.; Lampe, M.; Leonhardt, D.; Manheimer, W. M.; Murphy, D. P.; Walton, S. G.

2001-05-01

The use of moderate energy electron beams (e-beams) to generate plasma can provide greater control and larger area than existing techniques for processing applications. Kilovolt energy electrons have the ability to efficiently ionize low pressure neutral gas nearly independent of composition. This results in a low-temperature, high-density plasma of nearly controllable composition generated in the beam channel. By confining the electron beam magnetically the plasma generation region can be designated independent of surrounding structures. Particle fluxes to surfaces can then be controlled by the beam and gas parameters, system geometry, and the externally applied rf bias. The Large Area Plasma Processing System (LAPPS) utilizes a 1-5 kV, 2-10 mA/cm2 sheet beam of electrons to generate a 1011-1012cm-3 density, 1 eV electron temperature plasma. Plasma sheets of up to 60×60 cm2 area have been generated in a variety of molecular and atomic gases using both pulsed and cw e-beam sources. The theoretical basis for the plasma production and decay is presented along with experiments measuring the plasma density, temperature, and potential. Particle fluxes to nearby surfaces are measured along with the effects of radio frequency biasing. The LAPPS source is found to generate large-area plasmas suitable for materials processing.

High current densities enable exoelectrogens to outcompete aerobic heterotrophs for substrate

KAUST Repository

Ren, Lijiao

2014-08-05

© 2014 Wiley Periodicals, Inc. Chemical oxygen demand (COD) removal rates could be described by first-order kinetics with respect to COD concentration at different current densities, even under open circuit conditions with no current generation. The COD concentration was reduced more quickly with current generation due to the greater consumption of substrate by exoelectrogens, and less substrate was lost to aerobic heterotrophs. Higher current densities enabled exoelectrogens to outcompete aerobic heterotrophs for substrate, allowing for increased coulombic efficiencies with current densities. © 2014 Wiley Periodicals, Inc. In mixed-culture microbial fuel cells (MFCs), exoelectrogens and other microorganisms compete for substrate. It has previously been assumed that substrate losses to other terminal electron acceptors over a fed-batch cycle, such as dissolved oxygen, are constant. However, a constant rate of substrate loss would only explain small increases in coulombic efficiencies (CEs, the fraction of substrate recovered as electrical current) with shorter cycle times, but not the large increases in CE that are usually observed with higher current densities and reduced cycle times. To better understand changes in CEs, COD concentrations were measured over time in fed-batch, single-chamber, air-cathode MFCs at different current densities (external resistances). COD degradation rates were all found to be first-order with respect to COD concentration, even under open circuit conditions with no current generation (first-order rate constant of 0.14±0.01h-1). The rate of COD removal increased when there was current generation, with the highest rate constant (0.33±0.02h-1) obtained at the lowest external resistance (100Ω). Therefore, as the substrate concentration was reduced more quickly due to current generation, the rate of loss of substrate to non-exoelectrogens decreased due to this first-order substrate-concentration dependence. As a result, coulombic

High current densities enable exoelectrogens to outcompete aerobic heterotrophs for substrate

KAUST Repository

Ren, Lijiao; Zhang, Xiaoyuan; He, Weihua; Logan, Bruce E.

2014-01-01

© 2014 Wiley Periodicals, Inc. Chemical oxygen demand (COD) removal rates could be described by first-order kinetics with respect to COD concentration at different current densities, even under open circuit conditions with no current generation. The COD concentration was reduced more quickly with current generation due to the greater consumption of substrate by exoelectrogens, and less substrate was lost to aerobic heterotrophs. Higher current densities enabled exoelectrogens to outcompete aerobic heterotrophs for substrate, allowing for increased coulombic efficiencies with current densities. © 2014 Wiley Periodicals, Inc. In mixed-culture microbial fuel cells (MFCs), exoelectrogens and other microorganisms compete for substrate. It has previously been assumed that substrate losses to other terminal electron acceptors over a fed-batch cycle, such as dissolved oxygen, are constant. However, a constant rate of substrate loss would only explain small increases in coulombic efficiencies (CEs, the fraction of substrate recovered as electrical current) with shorter cycle times, but not the large increases in CE that are usually observed with higher current densities and reduced cycle times. To better understand changes in CEs, COD concentrations were measured over time in fed-batch, single-chamber, air-cathode MFCs at different current densities (external resistances). COD degradation rates were all found to be first-order with respect to COD concentration, even under open circuit conditions with no current generation (first-order rate constant of 0.14±0.01h-1). The rate of COD removal increased when there was current generation, with the highest rate constant (0.33±0.02h-1) obtained at the lowest external resistance (100Ω). Therefore, as the substrate concentration was reduced more quickly due to current generation, the rate of loss of substrate to non-exoelectrogens decreased due to this first-order substrate-concentration dependence. As a result, coulombic