WorldWideScience

Sample records for large uniformly distributed

  1. Measurement of fuel importance distribution in non-uniformly distributed fuel systems

    International Nuclear Information System (INIS)

    Yamane, Yoshihiro; Hirano, Yasushi; Yasui, Hazime; Izima, Kazunori; Shiroya, Seiji; Kobayashi, Keiji.

    1995-01-01

    A reactivity effect due to a spatial variation of nuclear fuel concentration is an important problem for nuclear criticality safety in a reprocessing plant. As a theory estimating this reactivity effect, the Goertzel and fuel importance theories are well known. It has been shown that the Goertzel's theory is valid in the range of our experiments based on measurements of reactivity effect and thermal neutron flux in non-uniformly distributed fuel systems. On the other hand, there have been no reports concerning systematic experimental studies on the flatness of fuel importance which is a more general index than the Goertzel's theory. It is derived from the perturbation theory that the fuel importance is proportional to the reactivity change resulting from a change of small amount of fuel mass. Using a uniform and three kinds of nonuniform fuel systems consisting of 93.2% enriched uranium plates and polyethylene plates, the fuel importance distributions were measured. As a result, it was found experimentally that the fuel importance distribution became flat, as its reactivity effect became large. Therefore it was concluded that the flatness of fuel importance distribution is the useful index for estimating reactivity effect of non-uniformly distributed fuel system. (author)

  2. Study of the distribution of maxima and minima in multiple sequential images of uniformity

    International Nuclear Information System (INIS)

    Llacer Martos, S.; Puchal Ane, R.

    2011-01-01

    To characterize the uniformity of a gamma camera extrinsic used integral uniformity coefficient is calculated with the value of two pixels, the maximum and minimum, single source acquisition of a flat and uniform. This method does not take into account the fact that if a gamma camera having a uniform response, the distribution of these items should be random. In this paper we study how these points are distributed in a succession of large numbers of uniform images.

  3. UOBPRM: A uniformly distributed obstacle-based PRM

    KAUST Repository

    Yeh, Hsin-Yi

    2012-10-01

    This paper presents a new sampling method for motion planning that can generate configurations more uniformly distributed on C-obstacle surfaces than prior approaches. Here, roadmap nodes are generated from the intersections between C-obstacles and a set of uniformly distributed fixed-length segments in C-space. The results show that this new sampling method yields samples that are more uniformly distributed than previous obstacle-based methods such as OBPRM, Gaussian sampling, and Bridge test sampling. UOBPRM is shown to have nodes more uniformly distributed near C-obstacle surfaces and also requires the fewest nodes and edges to solve challenging motion planning problems with varying narrow passages. © 2012 IEEE.

  4. Determining irrigation distribution uniformity and efficiency for nurseries

    Science.gov (United States)

    R. Thomas Fernandez

    2010-01-01

    A simple method for testing the distribution uniformity of overhead irrigation systems is described. The procedure is described step-by-step along with an example. Other uses of distribution uniformity testing are presented, as well as common situations that affect distribution uniformity and how to alleviate them.

  5. Uniform convergence of the empirical spectral distribution function

    NARCIS (Netherlands)

    Mikosch, T; Norvaisa, R

    1997-01-01

    Let X be a linear process having a finite fourth moment. Assume F is a class of square-integrable functions. We consider the empirical spectral distribution function J(n,X) based on X and indexed by F. If F is totally bounded then J(n,X) satisfies a uniform strong law of large numbers. If, in

  6. Voltage uniformity study in large-area reactors for RF plasma deposition

    Energy Technology Data Exchange (ETDEWEB)

    Sansonnens, L.; Pletzer, A.; Magni, D.; Howling, A.A.; Hollenstein, C. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP); Schmitt, J.P.M. [Balzers Process Systems, Palaiseau (France)

    1996-09-01

    Non-uniform voltage distribution across the electrode area results in inhomogeneous thin-film RF plasma deposition in large area reactors. In this work, a two-dimensional analytic model for the calculation of the voltage distribution across the electrode area is presented. The results of this model are in good agreement with measurements performed without plasma at 13.56 MHz and 70 MHz in a large area reactor. The principal voltage inhomogeneities are caused by logarithmic singularities in the vicinity of RF connections and not by standing waves. These singularities are only described by a two-dimensional model and cannot be intuitively predicted by analogy to a one-dimensional case. Plasma light emission measurements and thickness homogeneity studies of a-Si:H films show that the plasma reproduces these voltage inhomogeneities. Improvement of the voltage uniformity is investigated by changing the number and position of the RF connections. (author) 13 figs., 20 refs.

  7. Impact of uniform electrode current distribution on ETF

    Science.gov (United States)

    Bents, D. J.

    1982-01-01

    The design impacts on the ETF electrode consolidation network associated with uniform channel electrode current distribution are examined and the alternate consolidation design which occur are presented compared to the baseline (non-uniform current) design with respect to performance, and hardware requirements. A rational basis is given for comparing the requirements for the different designs and the savings that result from uniform current distribution. Performance and cost impacts upon the combined cycle plant are discussed.

  8. Tumour control probability (TCP) for non-uniform activity distribution in radionuclide therapy

    International Nuclear Information System (INIS)

    Uusijaervi, Helena; Bernhardt, Peter; Forssell-Aronsson, Eva

    2008-01-01

    Non-uniform radionuclide distribution in tumours will lead to a non-uniform absorbed dose. The aim of this study was to investigate how tumour control probability (TCP) depends on the radionuclide distribution in the tumour, both macroscopically and at the subcellular level. The absorbed dose in the cell nuclei of tumours was calculated for 90 Y, 177 Lu, 103m Rh and 211 At. The radionuclides were uniformly distributed within the subcellular compartment and they were uniformly, normally or log-normally distributed among the cells in the tumour. When all cells contain the same amount of activity, the cumulated activities required for TCP = 0.99 (A-tilde TCP=0.99 ) were 1.5-2 and 2-3 times higher when the activity was distributed on the cell membrane compared to in the cell nucleus for 103m Rh and 211 At, respectively. TCP for 90 Y was not affected by different radionuclide distributions, whereas for 177 Lu, it was slightly affected when the radionuclide was in the nucleus. TCP for 103m Rh and 211 At were affected by different radionuclide distributions to a great extent when the radionuclides were in the cell nucleus and to lesser extents when the radionuclides were distributed on the cell membrane or in the cytoplasm. When the activity was distributed in the nucleus, A-tilde TCP=0.99 increased when the activity distribution became more heterogeneous for 103m Rh and 211 At, and the increase was large when the activity was normally distributed compared to log-normally distributed. When the activity was distributed on the cell membrane, A-tilde TCP=0.99 was not affected for 103m Rh and 211 At when the activity distribution became more heterogeneous. A-tilde TCP=0.99 for 90 Y and 177 Lu were not affected by different activity distributions, neither macroscopic nor subcellular

  9. An Ad Hoc Adaptive Hashing Technique forNon-Uniformly Distributed IP Address Lookup in Computer Networks

    Directory of Open Access Journals (Sweden)

    Christopher Martinez

    2007-02-01

    Full Text Available Hashing algorithms long have been widely adopted to design a fast address look-up process which involves a search through a large database to find a record associated with a given key. Hashing algorithms involve transforming a key inside each target data to a hash value hoping that the hashing would render the database a uniform distribution with respect to this new hash value. The close the final distribution is to uniform, the less search time would be required when a query is made. When the database is already key-wise uniformly distributed, any regular hashing algorithm, such as bit-extraction, bit-group XOR, etc., would easily lead to a statistically perfect uniform distribution after the hashing. On the other hand, if records in the database are instead not uniformly distributed as in almost all known practical applications, then even different regular hash functions would lead to very different performance. When the target database has a key with a highly skewed distributed value, performance delivered by regular hashing algorithms usually becomes far from desirable. This paper aims at designing a hashing algorithm to achieve the highest probability in leading to a uniformly distributed hash result from a non-uniformly distributed database. An analytical pre-process on the original database is first performed to extract critical information that would significantly benefit the design of a better hashing algorithm. This process includes sorting on the bits of the key to prioritize the use of them in the XOR hashing sequence, or in simple bit extraction, or even a combination of both. Such an ad hoc hash design is critical to adapting to all real-time situations when there exists a changing (and/or expanding database with an irregular non-uniform distribution. Significant improvement from simulation results is obtained in randomly generated data as well as real data.

  10. On a Generalisation of Uniform Distribution and its Properties

    Directory of Open Access Journals (Sweden)

    K. Jayakumar

    2016-03-01

    Full Text Available Nadarajah et al.(2013 introduced a family life time models using truncated negative binomial distribution and derived some properties of the family of distributions. It is a generalization of Marshall-Olkin family of distributions. In this paper, we introduce Generalized Uniform Distribution (GUD using the approach of Nadarajah et al.(2013. The shape properties of density function and hazard function are discussed. The expression for moments, order statistics, entropies are obtained. Estimation procedure is also discussed.The GDU introduced here is a generalization of the Marshall-Olkin extended uniform distribution studied in Jose and Krishna(2011.

  11. Highly uniform parallel microfabrication using a large numerical aperture system

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zi-Yu; Su, Ya-Hui, E-mail: ustcsyh@ahu.edu.cn, E-mail: dongwu@ustc.edu.cn [School of Electrical Engineering and Automation, Anhui University, Hefei 230601 (China); Zhang, Chen-Chu; Hu, Yan-Lei; Wang, Chao-Wei; Li, Jia-Wen; Chu, Jia-Ru; Wu, Dong, E-mail: ustcsyh@ahu.edu.cn, E-mail: dongwu@ustc.edu.cn [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026 (China)

    2016-07-11

    In this letter, we report an improved algorithm to produce accurate phase patterns for generating highly uniform diffraction-limited multifocal arrays in a large numerical aperture objective system. It is shown that based on the original diffraction integral, the uniformity of the diffraction-limited focal arrays can be improved from ∼75% to >97%, owing to the critical consideration of the aperture function and apodization effect associated with a large numerical aperture objective. The experimental results, e.g., 3 × 3 arrays of square and triangle, seven microlens arrays with high uniformity, further verify the advantage of the improved algorithm. This algorithm enables the laser parallel processing technology to realize uniform microstructures and functional devices in the microfabrication system with a large numerical aperture objective.

  12. Temperature Uniformity of Wafer on a Large-Sized Susceptor for a Nitride Vertical MOCVD Reactor

    International Nuclear Information System (INIS)

    Li Zhi-Ming; Jiang Hai-Ying; Han Yan-Bin; Li Jin-Ping; Yin Jian-Qin; Zhang Jin-Cheng

    2012-01-01

    The effect of coil location on wafer temperature is analyzed in a vertical MOCVD reactor by induction heating. It is observed that the temperature distribution in the wafer with the coils under the graphite susceptor is more uniform than that with the coils around the outside wall of the reactor. For the case of coils under the susceptor, we find that the thickness of the susceptor, the distance from the coils to the susceptor bottom and the coil turns significantly affect the temperature uniformity of the wafer. An optimization process is executed for a 3-inch susceptor with this kind of structure, resulting in a large improvement in the temperature uniformity. A further optimization demonstrates that the new susceptor structure is also suitable for either multiple wafers or large-sized wafers approaching 6 and 8 inches

  13. High-uniformity centimeter-wide Si etching method for MEMS devices with large opening elements

    Science.gov (United States)

    Okamoto, Yuki; Tohyama, Yukiya; Inagaki, Shunsuke; Takiguchi, Mikio; Ono, Tomoki; Lebrasseur, Eric; Mita, Yoshio

    2018-04-01

    We propose a compensated mesh pattern filling method to achieve highly uniform wafer depth etching (over hundreds of microns) with a large-area opening (over centimeter). The mesh opening diameter is gradually changed between the center and the edge of a large etching area. Using such a design, the etching depth distribution depending on sidewall distance (known as the local loading effect) inversely compensates for the over-centimeter-scale etching depth distribution, known as the global or within-die(chip)-scale loading effect. Only a single DRIE with test structure patterns provides a micro-electromechanical systems (MEMS) designer with the etched depth dependence on the mesh opening size as well as on the distance from the chip edge, and the designer only has to set the opening size so as to obtain a uniform etching depth over the entire chip. This method is useful when process optimization cannot be performed, such as in the cases of using standard conditions for a foundry service and of short turn-around-time prototyping. To demonstrate, a large MEMS mirror that needed over 1 cm2 of backside etching was successfully fabricated using as-is-provided DRIE conditions.

  14. A method for producing uniform dose distributions in the junction regions of large hinge angle electrol fields

    International Nuclear Information System (INIS)

    Zavgorodni, S.F.; Beckham, W.A.; Roos, D.E.

    1996-01-01

    The planning problems presented by abutting electron fields are well recognised. Junctioning electron fields with large hinge angle compounds the problems because of the creation of closely situated 'hot' and 'cold' spots. The technique involving a compensated superficial x-ray (SXR) field to treat the junction region between electron fields was developed and used in a particular clinical case (treatment of a squamous cell carcinoma of the forehead/scalp). The SXR beam parameters were chosen and the compensator was designed to make the SXR field complementary to the electron fields. Application of a compensated SXR field eliminated 'cold' spots in the junction region and minimised 'hot' spots to (110%). In the clinical case discusses the 'hot' spots due to the SXR field would not appear because of increased attenuation of the soft x-rays in bone. The technique proposed produces uniform dose distribution up to 3 cm deep and can be considered as an additional tool for dealing with electron fields junctioning problems. (author)

  15. UOBPRM: A uniformly distributed obstacle-based PRM

    KAUST Repository

    Yeh, Hsin-Yi; Thomas, Shawna; Eppstein, David; Amato, Nancy M.

    2012-01-01

    This paper presents a new sampling method for motion planning that can generate configurations more uniformly distributed on C-obstacle surfaces than prior approaches. Here, roadmap nodes are generated from the intersections between C

  16. Effect of sprinkler structure on water distribution uniformity

    International Nuclear Information System (INIS)

    Xu, M; Li, H; Chen, C; Tu, Q; Liu, J P

    2012-01-01

    Structures of sprinklers play important roles in the uniformity of water distribution. The advances and achievements to improve the distribution uniformity through the innovation in the sprinkler structures at home and abroad were presented in details. Analyses showed that three types of structure can ameliorate the water distribution efficiently. First, novel nozzle structures were applied, including the application of non-circle nozzle and special spread nozzles. Second, new structures of flow channel were used. Third, assistant device was added so as to improve the uneven water distribution, such as an assistant stream interrupter, pressure or flow rate regulator and so on. Compared to domestic sprinklers, sprinklers produced abroad have novel and special structures with better hydraulic performance. Basic theoretical researches should be strengthened and new materials, new manufacturing processes and new technique should be applied. Then new kinds of sprinkler will be produced and the hydraulic performance of sprinklers will be promoted to a higher level.

  17. Impact of uniform electrode current distribution on ETF. [Engineering Test Facility MHD generator

    Science.gov (United States)

    Bents, D. J.

    1982-01-01

    A basic reason for the complexity and sheer volume of electrode consolidation hardware in the MHD ETF Powertrain system is the channel electrode current distribution, which is non-uniform. If the channel design is altered to provide uniform electrode current distribution, the amount of hardware required decreases considerably, but at the possible expense of degraded channel performance. This paper explains the design impacts on the ETF electrode consolidation network associated with uniform channel electrode current distribution, and presents the alternate consolidation designs which occur. They are compared to the baseline (non-uniform current) design with respect to performance, and hardware requirements. A rational basis is presented for comparing the requirements for the different designs and the savings that result from uniform current distribution. Performance and cost impacts upon the combined cycle plant are discussed.

  18. Modeling of parallel-plate regenerators with non-uniform plate distributions

    DEFF Research Database (Denmark)

    Jensen, Jesper Buch; Engelbrecht, Kurt; Bahl, Christian Robert Haffenden

    2010-01-01

    plate spacing distributions are presented in order to understand the impact of spacing non-uniformity. Simulations of more realistic distributions where the plate spacings follow normal distributions are then discussed in order to describe the deviation of the performance of a regenerator relative...

  19. PARALLEL AND ADAPTIVE UNIFORM-DISTRIBUTED REGISTRATION METHOD FOR CHANG’E-1 LUNAR REMOTE SENSED IMAGERY

    Directory of Open Access Journals (Sweden)

    X. Ning

    2012-08-01

    To resolve the above-mentioned registration difficulties, a parallel and adaptive uniform-distributed registration method for CE-1 lunar remote sensed imagery is proposed in this paper. Based on 6 pairs of randomly selected images, both the standard SIFT algorithm and the parallel and adaptive uniform-distributed registration method were executed, the versatility and effectiveness were assessed. The experimental results indicate that: by applying the parallel and adaptive uniform-distributed registration method, the efficiency of CE-1 lunar remote sensed imagery registration were increased dramatically. Therefore, the proposed method in the paper could acquire uniform-distributed registration results more effectively, the registration difficulties including difficult to obtain results, time-consuming, non-uniform distribution could be successfully solved.

  20. Curved-straight neutron guide system with uniform spatial intensity distribution

    International Nuclear Information System (INIS)

    Mildner, D.F.R.; Cook, J.C.

    2008-01-01

    The spatial intensity distribution of neutrons emerging from a curved guide is asymmetric, and straight guide sections are sometimes appended to curved guides to make the intensity distribution more nearly uniform. For idealized uniform illumination and in the perfect reflectivity approximation, the spatial-angular acceptance at the exit of the combination can be made exactly uniform for a range of long wavelengths by using a sufficiently long straight section, together with a curved guide whose outer wall coating has a critical angle slightly greater than those of the other guide walls. We refer to this as a 'phase space tailoring guide' where the coatings on the inner wall and straight section are used to define the required divergence at the end of the guide. Increasing the critical angle of the outer wall of the curved section reduces the characteristic wavelength of the curved guide as well as the wavelength at which ideal uniformity can be obtained. The outer wall coating need only be of sufficiently high critical angle to fill the transmittable phase space area of the straight guide uniformly to adequately short wavelength

  1. Experimental study on generation of large area uniform electron beam

    International Nuclear Information System (INIS)

    Tang Ying; Yi Aiping; Liu Jingru; Qian Hang; Huang Xin; Yu Li; Su Jiancang; Ding Zhenjie; Ding Yongzhong; Yu Jianguo

    2007-01-01

    In the experiment of gas laser pumped by electron beam, large area uniform electron beam is important to generate high efficiency laser output. The experimental study on generation of large area uniform electron beam with SPG-200 pulsed power generator is introduced. SPG-200 is an all-solid-state components pulsed power generator based on SOS, and its open voltage is more than 350 kV. The cathode have the area of 24 mm x 294 mm, and the anode-cathode(A-C)gap spacing is adjustable from 0 to 49 mm. The electron beam of cathode emission is transported to the laser chamber through the diode pressure foil, which sepa-rates the vacuum chamber from the laser chamber. Velvet and graphite cathodes are studied, each generates large area electron beam. The diode parameters are presented, and the uniformity of e-beam is diagnosed. The experimental results show that the diode voltage of the graphite cathode is 240-280 kV, and the diode current is 0.7-1.8 kA. The diode voltage of the velvet cathode is 200-250 kV, and the diode current is 1.5-1.7 kA. The uniformity of the velvet cathode emission is better than that of the graphite cathode. (authors)

  2. In-plane modal frequencies and mode shapes of two stay cables interconnected by uniformly distributed cross-ties

    Science.gov (United States)

    Jing, Haiquan; He, Xuhui; Zou, Yunfeng; Wang, Hanfeng

    2018-03-01

    Stay cables are important load-bearing structural elements of cable-stayed bridges. Suppressing the large vibrations of the stay cables under the external excitations is of worldwide concern for the bridge engineers and researchers. Over the past decade, the use of crosstie has become one of the most practical and effective methods. Extensive research has led to a better understanding of the mechanics of cable networks, and the effects of different parameters, such as length ratio, mass-tension ratio, and segment ratio on the effectiveness of the crosstie have been investigated. In this study, uniformly distributed elastic crossties serve to replace the traditional single, or several cross-ties, aiming to delay "mode localization." A numerical method is developed by replacing the uniformly distributed, discrete elastic cross-tie model with an equivalent, continuously distributed, elastic cross-tie model in order to calculate the modal frequencies and mode shapes of the cable-crosstie system. The effectiveness of the proposed method is verified by comparing the elicited results with those obtained using the previous method. The uniformly distributed elastic cross-ties are shown to significantly delay "mode localization."

  3. Study of the distribution of maxima and minima in multiple sequential images of uniformity; Estudio de la distribucion de maximos y minimos en multiples imagenes secuenciales de uniformidad

    Energy Technology Data Exchange (ETDEWEB)

    Llacer Martos, S.; Puchal Ane, R.

    2011-07-01

    To characterize the uniformity of a gamma camera extrinsic used integral uniformity coefficient is calculated with the value of two pixels, the maximum and minimum, single source acquisition of a flat and uniform. This method does not take into account the fact that if a gamma camera having a uniform response, the distribution of these items should be random. In this paper we study how these points are distributed in a succession of large numbers of uniform images.

  4. Problem of uniqueness in the renewal process generated by the uniform distribution

    Directory of Open Access Journals (Sweden)

    D. Ugrin-Šparac

    1992-01-01

    Full Text Available The renewal process generated by the uniform distribution, when interpreted as a transformation of the uniform distribution into a discrete distribution, gives rise to the question of uniqueness of the inverse image. The paper deals with a particular problem from the described domain, that arose in the construction of a complex stochastic test intended to evaluate pseudo-random number generators. The connection of the treated problem with the question of a unique integral representation of Gamma-function is also mentioned.

  5. Large eddy simulation of a buoyancy-aided flow in a non-uniform channel – Buoyancy effects on large flow structures

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Y. [Department of Mechanical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester M13 9PL (United Kingdom); He, S., E-mail: s.he@sheffield.ac.uk [Department of Mechanical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2017-02-15

    Highlights: • Buoyancy may greatly redistribute the flow in a non-uniform channel. • Flow structures in the narrow gap are greatly changed when buoyancy is strong. • Large flow structures exist in wider gap, which is enhanced when heat is strong. • Buoyancy reduces mixing factor caused by large flow structures in narrow gap. - Abstract: It has been a long time since the ‘abnormal’ turbulent intensity distribution and high inter-sub-channel mixing rates were observed in the vicinity of the narrow gaps formed by the fuel rods in nuclear reactors. The extraordinary flow behaviour was first described as periodic flow structures by Hooper and Rehme (1984). Since then, the existences of large flow structures were demonstrated by many researchers in various non-uniform flow channels. It has been proved by many authors that the Strouhal number of the flow structure in the isothermal flow is dependent on the size of the narrow gap, not the Reynolds number once it is sufficiently large. This paper reports a numerical investigation on the effect of buoyancy on the large flow structures. A buoyancy-aided flow in a tightly-packed rod-bundle-like channel is modelled using large eddy simulation (LES) together with the Boussinesq approximation. The behaviour of the large flow structures in the gaps of the flow passage are studied using instantaneous flow fields, spectrum analysis and correlation analysis. It is found that the non-uniform buoyancy force in the cross section of the flow channel may greatly redistribute the velocity field once the overall buoyancy force is sufficiently strong, and consequently modify the large flow structures. The temporal and axial spatial scales of the large flow structures are influenced by buoyancy in a way similar to that turbulence is influenced. These scales reduce when the flow is laminarised, but start increasing in the turbulence regeneration region. The spanwise scale of the flow structures in the narrow gap remains more or

  6. Continuous-variable quantum key distribution in uniform fast-fading channels

    Science.gov (United States)

    Papanastasiou, Panagiotis; Weedbrook, Christian; Pirandola, Stefano

    2018-03-01

    We investigate the performance of several continuous-variable quantum key distribution protocols in the presence of uniform fading channels. These are lossy channels whose transmissivity changes according to a uniform probability distribution. We assume the worst-case scenario where an eavesdropper induces a fast-fading process, where she chooses the instantaneous transmissivity while the remote parties may only detect the mean statistical effect. We analyze coherent-state protocols in various configurations, including the one-way switching protocol in reverse reconciliation, the measurement-device-independent protocol in the symmetric configuration, and its extension to a three-party network. We show that, regardless of the advantage given to the eavesdropper (control of the fading), these protocols can still achieve high rates under realistic attacks, within reasonable values for the variance of the probability distribution associated with the fading process.

  7. Uniformity studies in large area triple-GEM based detectors

    Energy Technology Data Exchange (ETDEWEB)

    Akl, M. Abi [Science Program, Texas A& M University at Qatar, PO Box 23874, Doha (Qatar); Bouhali, O., E-mail: othmane.bouhali@qatar.tamu.edu [Science Program, Texas A& M University at Qatar, PO Box 23874, Doha (Qatar); Qatar Computing Research Institute, Hamad Bin Khalifa University, PO Box 5825, Doha (Qatar); Castaneda, A.; Maghrbi, Y.; Mohamed, T. [Science Program, Texas A& M University at Qatar, PO Box 23874, Doha (Qatar)

    2016-10-01

    Gas Electron Multiplier (GEM) based detectors have been used in many applications since their introduction in 1997. Large areas, e.g. exceeding 30×30 cm{sup 2}, of GEM detectors are foreseen in future experiments which puts stringent requirements on the uniformity of response across the detection area. We investigate the effect of small variations of several parameters that could affect the uniformity. Parameters such as the anode pitch, the gas gap, the size and the shape of the holes are investigated. Simulation results are presented and compared to previous experimental data.

  8. Design of internally heat-integrated distillation column (HIDiC): Uniform heat transfer area versus uniform heat distribution

    Energy Technology Data Exchange (ETDEWEB)

    Suphanit, B. [Department of Chemical Engineering, Faculty of Engineering, King Mongkut' s University of Technology Thonburi, Pracha Utit Rd., Tungkru, Bangkok 10140 (Thailand)

    2010-03-15

    The internally heat-integrated distillation column (HIDiC) is a complex column configuration which is more energy efficient than the equivalent conventional column or the distillation column with direct vapor recompression scheme (VRC). Exploiting the heat integration between two diabatic sections operating at different pressures of the HIDiC can greatly enhance the energy performance of the system. On the other hand, the design and optimization of HIDiC is more difficult than those of the conventional distillation column or the column with VRC. The former involves many design parameters, and the most critical one is the pressure ratio between both diabatic sections. However, the heat distribution along the diabatic sections is also another significant factor not yet thoroughly investigated. In this work, two typical distribution schemes, i.e. uniform heat transfer area and uniform heat distribution, are studied by applying a novel approach to solve the simulation problem in Aspen Plus 2004.1. The comparison of both distributing schemes is discussed via two widely-used case studies, namely benzene-toluene separation and propylene-propane splitter. (author)

  9. A large volume uniform plasma generator for the experiments of electromagnetic wave propagation in plasma

    International Nuclear Information System (INIS)

    Yang Min; Li Xiaoping; Xie Kai; Liu Donglin; Liu Yanming

    2013-01-01

    A large volume uniform plasma generator is proposed for the experiments of electromagnetic (EM) wave propagation in plasma, to reproduce a “black out” phenomenon with long duration in an environment of the ordinary laboratory. The plasma generator achieves a controllable approximate uniform plasma in volume of 260 mm× 260 mm× 180 mm without the magnetic confinement. The plasma is produced by the glow discharge, and the special discharge structure is built to bring a steady approximate uniform plasma environment in the electromagnetic wave propagation path without any other barriers. In addition, the electron density and luminosity distributions of plasma under different discharge conditions were diagnosed and experimentally investigated. Both the electron density and the plasma uniformity are directly proportional to the input power and in roughly reverse proportion to the gas pressure in the chamber. Furthermore, the experiments of electromagnetic wave propagation in plasma are conducted in this plasma generator. Blackout phenomena at GPS signal are observed under this system and the measured attenuation curve is of reasonable agreement with the theoretical one, which suggests the effectiveness of the proposed method.

  10. Evidence for large-scale uniformity of physical laws

    International Nuclear Information System (INIS)

    Tubbs, A.D.; Wolfe, A.M.

    1980-01-01

    The coincidence of redshifts deduced from 21 cm and resonance transitions in absorbing gas detected in front of four quasi-stellar objects results in stringent limits on the variation of the product of three physical constants both in space and in time. We find that α 2 g/sub p/(m/M) is spatially uniform, to a few parts in 10 4 , throughout the observable universe. This uniformity holds subsequent to an epoch corresponding to less than 5% of the current age of the universe t 0 . Moreover, time variations in α 2 g/sub p/m/M are excluded to the same accuracy subsequent to an epoch corresponding to > or approx. =0.20 t 0 . These limits are largely model independent, relying only upon the cosmoligical interpretation of redshifts, and the isotropy of the 3 K background radiation. That a quantity as complex as g/sub p/, which depends on all the details of strong interaction physics, is uniform throughout most of spacetime, even in causally disjoint regions, suggests that all physical laws are globally invariant

  11. Effect of air gap on uniformity of large-scale surface-wave plasma

    International Nuclear Information System (INIS)

    Lan Chaohui; Hu Xiwei; Jiang Zhonghe; Liu Minghai

    2009-01-01

    The effect of air gap on the uniformity of large-scale surface-wave plasma (SWP) in a rectangular chamber device is studied by using three-dimensional numerical analyses based on the finite difference time-domain (FDTD) approximation to Maxwell's equations and plasma fluid model. The spatial distributions of surface wave excited by slot-antenna array and the plasma parameters such as electron density and temperature are presented. For different air gap thicknesses, the results show that the existence of air gap would severely weaken the excitations of the surface wave and thereby the SWP. Thus the air gap should be eliminated completely in the design of the SWP source, which is opposite to the former research results. (authors)

  12. Forecasting the Rupture Directivity of Large Earthquakes: Centroid Bias of the Conditional Hypocenter Distribution

    Science.gov (United States)

    Donovan, J.; Jordan, T. H.

    2012-12-01

    Forecasting the rupture directivity of large earthquakes is an important problem in probabilistic seismic hazard analysis (PSHA), because directivity is known to strongly influence ground motions. We describe how rupture directivity can be forecast in terms of the "conditional hypocenter distribution" or CHD, defined to be the probability distribution of a hypocenter given the spatial distribution of moment release (fault slip). The simplest CHD is a uniform distribution, in which the hypocenter probability density equals the moment-release probability density. For rupture models in which the rupture velocity and rise time depend only on the local slip, the CHD completely specifies the distribution of the directivity parameter D, defined in terms of the degree-two polynomial moments of the source space-time function. This parameter, which is zero for a bilateral rupture and unity for a unilateral rupture, can be estimated from finite-source models or by the direct inversion of seismograms (McGuire et al., 2002). We compile D-values from published studies of 65 large earthquakes and show that these data are statistically inconsistent with the uniform CHD advocated by McGuire et al. (2002). Instead, the data indicate a "centroid biased" CHD, in which the expected distance between the hypocenter and the hypocentroid is less than that of a uniform CHD. In other words, the observed directivities appear to be closer to bilateral than predicted by this simple model. We discuss the implications of these results for rupture dynamics and fault-zone heterogeneities. We also explore their PSHA implications by modifying the CyberShake simulation-based hazard model for the Los Angeles region, which assumed a uniform CHD (Graves et al., 2011).

  13. An explicit local uniform large deviation bound for Brownian bridges

    NARCIS (Netherlands)

    Wittich, O.

    2005-01-01

    By comparing curve length in a manifold and a standard sphere, we prove a local uniform bound for the exponent in the Large Deviation formula that describes the concentration of Brownian bridges to geodesics.

  14. Analytical examination of a spiral beam scanning method for uniform irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Mitsuhiro; Okumura, Susumu; Arakawa, Kazuo [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    1997-03-01

    A new circular beam scanning method for uniform irradiation of high-energy, intense ion beams over a large area has been developed. A sweeping speed and a trajectory density in a radial direction are kept constant to obtain uniform fluence distribution. A radial position of a beam spot on a target and an angular frequency of the circular motion are expressed by an irrational function of time. The beam is swept continuously, and a beam trajectory becomes spiral. More than 90 % uniformity of the fluence distribution can been achieved over a large area. (author)

  15. Analysis of the Elastic Large Deflection Behavior for Metal Plates under Nonuniformly Distributed Lateral Pressure with In-Plane Loads

    Directory of Open Access Journals (Sweden)

    Jeom Kee Paik

    2012-01-01

    Full Text Available The Galerkin method is applied to analyze the elastic large deflection behavior of metal plates subject to a combination of in-plane loads such as biaxial loads, edge shear and biaxial inplane bending moments, and uniformly or nonuniformly distributed lateral pressure loads. The motive of the present study was initiated by the fact that metal plates of ships and ship-shaped offshore structures at sea are often subjected to non-uniformly distributed lateral pressure loads arising from cargo or water pressure, together with inplane axial loads or inplane bending moments, but the current practice of the maritime industry usually applies some simplified design methods assuming that the non-uniform pressure distribution in the plates can be replaced by an equivalence of uniform pressure distribution. Applied examples are presented, demonstrating that the current plate design methods of the maritime industry may be inappropriate when the non-uniformity of lateral pressure loads becomes more significant.

  16. Investigation of Non-Uniform Rust Distribution and Its Effects on Corrosion Induced Cracking in Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Sutrisno Wahyuniarsih

    2017-01-01

    Full Text Available Uniform corrosion still widely used by a lot of researchers and engineers to analyze the corrosion induced cracking. However, in practice, corrosion process occurred non-uniformly. The part nearest to the exposed surface is more likely to have faster corrosion initiation compared with other regions. This research is mainly focused on investigating the effect of non-uniform rust distribution to cover cracking in reinforced concrete. An experimental test performed using accelerated corrosion test by using 5% NaCl solution and applied a constant electric current to the concrete samples. The rust distribution and measurement were observed by using a digital microscope. Based on the experimental result, it was found that the rust was distributed in a non-uniform pattern. As a result, the cracks also formed non-uniformly along the perimeter of steel bar. At the last part of this paper, a simulation result of concrete cracking induced by non-uniform corrosion is presented. The result compared with a simulation using uniform corrosion assumption to investigate the damage pattern of each model. The simulation result reveals stress evolution due to rust expansion which leads to concrete cracking. Furthermore, a comparison of stresses induced by non-uniform corrosion and uniform corrosion indicates that non-uniform corrosion could lead to earlier damage to the structure which is specified by the formation and propagation of the crack.

  17. Skin carcinogenesis following uniform and non-uniform β irradiation

    International Nuclear Information System (INIS)

    Charles, M.W.; Williams, J.P.; Coggle, J.E.

    1989-01-01

    Where workers or the general public may be exposed to ionising radiation, the irradiation is rarely uniform. The risk figures and dose limits recommended by the International Commission on Radiological Protection (ICRP) are based largely on clinical and epidemiological studies of reasonably uniform irradiated organs. The paucity of clinical or experimental data for highly non-uniform exposures has prevented the ICRP from providing adequate recommendations. This weakness has led on a number of occasions to the postulate that highly non-uniform exposures of organs could be 100,000 times more carcinogenic than ICRP risk figures would predict. This so-called ''hot-particle hypothesis'' found little support among reputable radiobiologists, but could not be clearly and definitively refuted on the basis of experiment. An experiment, based on skin tumour induction in mouse skin, is described which was developed to test the hypothesis. The skin of 1200 SAS/4 male mice has been exposed to a range of uniform and non-uniform sources of the β emitter 170 Tm (E max ∼ 1 MeV). Non-uniform exposures were produced using arrays of 32 or 8 2-mm diameter sources distributed over the same 8-cm 2 area as a uniform control source. Average skin doses varied from 2-100 Gy. The results for the non-uniform sources show a 30% reduction in tumour incidence by the 32-point array at the lower mean doses compared with the response from uniform sources. The eight-point array showed an order-of-magnitude reduction in tumour incidence compared to uniform irradiation at low doses. These results, in direct contradiction to the ''hot particle hypothesis'', indicate that non-uniform exposures produce significantly fewer tumours than uniform exposures. (author)

  18. Large-area uniform electron doping of graphene by Ag nanofilm

    Directory of Open Access Journals (Sweden)

    Xiaopeng Guo

    2017-04-01

    Full Text Available Graphene has attracted much attention at various research fields due to its unique optical, electronic and mechanical properties. Up to now, graphene has not been widely used in optoelectronic fields due to the lack of large-area uniform doped graphene (n-doped and p-doped with smooth surface. Therefore, it is rather desired to develop some effective doping methods to extend graphene to optoelectronics. Here we developed a novel doping method to prepare large-area (> centimeter scale uniform doped graphene film with a nanoscale roughness(RMS roughness ∼1.4 nm, the method (nano-metal film doping method is simple but effective. Using this method electron doping (electron-injection may be easily realized by the simple thermal deposition of Ag nano-film on a transferred CVD graphene. The doping effectiveness has been proved by Raman spectroscopy and spectroscopic ellipsometry. Importantly, our method sheds light on some potential applications of graphene in optoelectronic devices such as photodetectors, LEDs, phototransistors, solar cells, lasers etc.

  19. The prediction of burnout in non-uniformly heated rod clusters from burnout data for uniformly heated round tubes

    International Nuclear Information System (INIS)

    Barnett, P.G.

    1964-11-01

    The practice of using burnout data for uniformly heated round tubes to predict burnout in non-uniformly heated reactor channels having complex cross sections is examined. At least two hypotheses are involved: (i) a relationship exists between uniform and non-uniform heat flux distributions and (ii) a relationship exists between simple and complex channel cross sections. Use of two such hypotheses each accurate to ± 15% and a correlation of uniformly heated round tube data having an R.M.S. error of 5%, could yield errors of ± 40% in any predicted value; this figure of ± 40% is regarded as a realistic upper limit for design purposes. It is shown that no method can exist for relating different channel cross sections to within ± 15% and existing methods for relating different heat flux distributions incur some errors exceeding 20%. Furthermore, any suggested method for relating different heat flux distributions can be adequately checked only when a sufficiently large number of results are available and then the preferable alternative of correlating the data is possible. It is concluded that no reliable method can exist for predicting burnout in rod bundles from uniformly heated round tube data with sufficient accuracy for design purposes. (author)

  20. Uniform distribution of TiCp in TiCp/Zn-Al composites prepared by XDTM

    Institute of Scientific and Technical Information of China (English)

    王香; 马旭梁; 李庆芬; 曾松岩

    2002-01-01

    The prefabricated Al/TiC alloy with high TiC particle content was prepared by XDTM process. The uniform distribution process of TiC particles in the stationary zinc melt was studied and analyzed using self-made experimental equipment, and the model of the uniform distribution process was built. The results show that zinc diffuses into the prepared Al/TiC alloy after it is placed in the zinc melt at temperatures below the melting point of aluminum, which leads to the decrease of the liquidus temperature of Al-Zn alloy in the surface layer of Al/TiC alloy. When the liquidus temperature of Al-Zn alloy is equal to or below the temperature of zinc melt, Al-Zn alloy melts and TiC particles drop with it from the Al/TiC alloy and then transfer into the zinc melt and finally distribute uniformly in it.

  1. Uniform irradiation system using beam scanning method for cyclotron

    International Nuclear Information System (INIS)

    Agematsu, Takashi; Okumura, Susumu; Arakawa, Kazuo

    1994-03-01

    JAERI AVF-cyclotron is equipped with an ion beam scanner for large area irradiation. The two-dimensional fluence distribution of ion beam obtained using cellulose triacetate film dosimeter was not uniform. This is resulted from the distortion of excitation current for electromagnet of the scanner. So, the beam scanning condition, i.e., the relation between the ion species, the beam profile and the scanning width, was extremely limited to make a good uniformity. We have developed a beam scanning simulator to get fluence distributions by calculation and then compared the simulated distributions with the measured ones. It was revealed that the both of them are in good agreement and the beam scanning condition to get good uniformity was led by using this simulator. On the basis of these results, the power supply of scanner was improved. A good uniformity of beam distribution was available. (author)

  2. High density, uniformly distributed W/UO2 for use in Nuclear Thermal Propulsion

    Science.gov (United States)

    Tucker, Dennis S.; Barnes, Marvin W.; Hone, Lance; Cook, Steven

    2017-04-01

    An inexpensive, quick method has been developed to obtain uniform distributions of UO2 particles in a tungsten matrix utilizing 0.5 wt percent low density polyethylene. Powders were sintered in a Spark Plasma Sintering (SPS) furnace at 1600 °C, 1700 °C, 1750 °C, 1800 °C and 1850 °C using a modified sintering profile. This resulted in a uniform distribution of UO2 particles in a tungsten matrix with high densities, reaching 99.46% of theoretical for the sample sintered at 1850 °C. The powder process is described and the results of this study are given below.

  3. Temperature distribution in a uniformly moving medium

    International Nuclear Information System (INIS)

    Mitchell, Joseph D; Petrov, Nikola P

    2009-01-01

    We apply several physical ideas to determine the steady temperature distribution in a medium moving with uniform velocity between two infinite parallel plates. We compute it in the coordinate frame moving with the medium by integration over the 'past' to account for the influence of an infinite set of instantaneous point sources of heat in past moments as seen by an observer moving with the medium. The boundary heat flux is simulated by appropriately distributed point heat sources on the inner side of an adiabatically insulating boundary. We make an extensive use of the Green functions with an emphasis on their physical meaning. The methodology used in this paper is of great pedagogical value as it offers an opportunity for students to see the connection between powerful mathematical techniques and their physical interpretation in an intuitively clear physical problem. We suggest several problems and a challenging project that can be easily incorporated in undergraduate or graduate courses

  4. Large-scale syntheses of uniform ZnO nanorods and ethanol gas sensors application

    International Nuclear Information System (INIS)

    Chen Jin; Li Jin; Li Jiahui; Xiao Guoqing; Yang Xiaofeng

    2011-01-01

    Research highlights: → The uniform ZnO nanorods could be synthesized by a low temperature, solution-based method. → The results showed that the sample had uniform rod-like morphology with a narrow size distribution and highly crystallinity. → Room-temperature photoluminescence spectra of these nanorods show an exciton emission around 382 nm and a weak deep level emission, indicating the nanorods have high quality. → The sensor exhibited high sensitivity and fast response to ethanol gas at a work temperature of 400 deg. C. - Abstract: Uniform ZnO nanorods with a gram scale were prepared by a low temperature and solution-based method. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL). The results showed that the sample had uniform rod-like morphology with a narrow size distribution and highly crystallinity. Room-temperature PL spectra of these nanorods show an exciton emission around 382 nm and a negligible deep level emission, indicating the nanorods have high quality. The gas-sensing properties of the materials have been investigated. The results indicate that the as-prepared nanorods show much better sensitivity and stability. The n-type semiconductor gas sensor exhibited high sensitivity and fast response to ethanol gas at a work temperature of 400 deg. C. ZnO nanorods are excellent potential candidates for highly sensitive gas sensors and ultraviolet laser.

  5. On the burnout in annular channels at non-uniform heat release distribution in length

    International Nuclear Information System (INIS)

    Ornatskij, A.P.; Chernobaj, V.A.; Vasil'ev, A.F.; Struts, G.V.

    1982-01-01

    The effect of axial heat release non-uniformity on the conditions of the burnout in annular channels is investigated. The investigation is carried out in annular channels with different laws of heat flux density distribution by channel length. The heat release non-uniformity coefficient was varied from 4.4 to 10, the pressure from 9.8 to 17.6 MPa, mass rate from 500 to 1700 kg (m 2 xS), liquid temperature (chemically desalted water) at the channel inlet constituted 30-300 deg C. The experiments have been performed at the test bench with a closed circulation circuit. The data obtained testify to the fact that under non-uniform heat release the influence of main operating parameters on the value of critical power is of the same character as under uniform heat release. The character of wall temperature variation by channel length before the burnout is determined by the form of heat supply temperature profile. The temperature maximum is observed in the region lying behind the cross section with maximum heat flux. The conclusion is drawn that the dominant influence on the position of the cross section in which the burnout arises is exerted by the form of heat flux density distribution by length. Independently of this distribution form the burnout developes when the vapour content near the wall reaches a limiting value

  6. Comparisons of uniform and discrete source distributions for use in bioassay laboratory performance testing

    International Nuclear Information System (INIS)

    Scherpelz, R.I.; MacLellan, J.A.

    1987-09-01

    The Pacific Northwest Laboratory (PNL) is sending a torso phantom with radioactive material uniformly distributed in the lungs to in vivo bioassay laboratories for analysis. Although the radionuclides ultimately chosen for the studies had relatively long half-lives, future accreditation testing will require repeated tests with short half-life test nuclides. Computer modeling was used to simulate the major components of the phantom. Radiation transport calculations were then performed using the computer models to calculate dose rates either 15 cm from the chest or at its surface. For 144 Ce and 60 Co, three configurations were used for the lung comparison tests. Calculations show that, for most detector positions, a single plug containing 40 K located in the back of the heart provides a good approximation to a uniform distribution of 40 K. The approximation would lead, however, to a positive bias for the detector reading if the detector were located at the chest surface near the center. Loading the 40 K in a uniform layer inside the chest wall is not a good approximation of the uniform distribution in the lungs, because most of the radionuclides would be situated close to the detector location and the only shielding would be the thickness of the chest wall. The calculated dose rates for 60 Co and 144 Ce were similar at all calculated reference points. 3 refs., 5 figs., 10 tabs

  7. Control of field uniformity for a large superconducting storage ring magnet

    International Nuclear Information System (INIS)

    Danby, G.T.; Jackson, J.W.

    1994-01-01

    A 1.45 Tesla, 14.2 meter diameter ''superferric'' magnet is in an advanced stage of construction at BNL. This magnet will be used to store muons for a planned ultra-precise measurement of their anomalous magnetic moment g-2. This measurement requires a magnetic field uniformity of 1 PPM with a knowledge of the field over the muon orbits to 0.1 PPM. The methods built into the design to produce ultra-high field uniformity will be described. Large deviations from the ideal circularly symmetric uniform shape of the iron flux path are required to accommodate transfer lines and superconducting current leads, as well as apparatus for beam injection. Shimming methods to correct for the perturbations due to these large holes will be presented. The pole pieces consist of 36 closely fitting 10 degree arc sections butted together to produce a very good approximation to a continuous 360 degree ring magnet. However, in the cast of a possible quench of the superconducting coils, significant eddy currents will be induced which will circulate within the confines of each 10 degree pole piece. At the great precision required, these eddy currents may leave very small but significant aberrations in the field even after they decay away, because of slight changes in the orientation of the magnetization. Surface coil possibilities to correct for this effect will be described

  8. Analysis of Causes of Non-Uniform Flow Distribution in Manifold Systems with Variable Flow Rate along Length

    Science.gov (United States)

    Zemlyanaya, N. V.; Gulyakin, A. V.

    2017-11-01

    The uniformity of flow distribution in perforated manifolds is a relevant task. The efficiency of water supply, sewerage and perflation systems is determined by hydraulics of the flow with a variable mass. The extensive study of versatile available information showed that achieving a uniform flow distribution through all of the outlets is almost impossible. The analysis of the studies conducted by other authors and our numerical experiments performed with the help of the software package ANSYS 16.1 were made in this work. The results allowed us to formulate the main causes of non-uniform flow distribution. We decided to suggest a hypothesis to explain the static pressure rise problem at the end of a perforated manifold.

  9. Uniform distribution and quasi-Monte Carlo methods discrepancy, integration and applications

    CERN Document Server

    Kritzer, Peter; Pillichshammer, Friedrich; Winterhof, Arne

    2014-01-01

    The survey articles in this book focus on number theoretic point constructions, uniform distribution theory, and quasi-Monte Carlo methods. As deterministic versions of the Monte Carlo method, quasi-Monte Carlo rules enjoy increasing popularity, with many fruitful applications in mathematical practice, as for example in finance, computer graphics, and biology.

  10. Nonimaging polygonal mirrors achieving uniform irradiance distributions on concentrating photovoltaic cells.

    Science.gov (United States)

    Schmitz, Max; Dähler, Fabian; Elvinger, François; Pedretti, Andrea; Steinfeld, Aldo

    2017-04-10

    We introduce a design methodology for nonimaging, single-reflection mirrors with polygonal inlet apertures that generate a uniform irradiance distribution on a polygonal outlet aperture, enabling a multitude of applications within the domain of concentrated photovoltaics. Notably, we present single-mirror concentrators of square and hexagonal perimeter that achieve very high irradiance uniformity on a square receiver at concentrations ranging from 100 to 1000 suns. These optical designs can be assembled in compound concentrators with maximized active area fraction by leveraging tessellation. More advanced multi-mirror concentrators, where each mirror individually illuminates the whole area of the receiver, allow for improved performance while permitting greater flexibility for the concentrator shape and robustness against partial shading of the inlet aperture.

  11. Modelling non-uniform strain distributions in aerospace composites using fibre Bragg gratings

    NARCIS (Netherlands)

    Rajabzadehdizaji, Aydin; Groves, R.M.; Hendriks, R.C.; Heusdens, R.; Chung, Y.; Jin, W.; Lee, B.; Canning, J.; Nakamura, K.; Yuan, L.

    2017-01-01

    In this paper the behaviour of fibre Bragg grating (FBG) sensors under non-uniform strain distributions was analysed. Using the fundamental matrix approach, the length of the FBG sensor was discretised, with each segment undergoing different strain values. FBG sensors that are embedded inside

  12. Environmental radionuclide concentrations: statistical model to determine uniformity of distribution

    International Nuclear Information System (INIS)

    Cawley, C.N.; Fenyves, E.J.; Spitzberg, D.B.; Wiorkowski, J.; Chehroudi, M.T.

    1980-01-01

    In the evaluation of data from environmental sampling and measurement, a basic question is whether the radionuclide (or pollutant) is distributed uniformly. Since physical measurements have associated errors, it is inappropriate to consider the measurements alone in this determination. Hence, a statistical model has been developed. It consists of a weighted analysis of variance with subsequent t-tests between weighted and independent means. A computer program to perform the calculations is included

  13. High density, uniformly distributed W/UO{sub 2} for use in Nuclear Thermal Propulsion

    Energy Technology Data Exchange (ETDEWEB)

    Tucker, Dennis S., E-mail: dr.dennis.tucker@nasa.gov [EM32, MSFC, Al 35812 (United States); Barnes, Marvin W. [EM32, MSFC, Al 35812 (United States); Hone, Lance; Cook, Steven [Center for Space Nuclear Research, Idaho Falls, ID 83401 (United States)

    2017-04-01

    An inexpensive, quick method has been developed to obtain uniform distributions of UO{sub 2} particles in a tungsten matrix utilizing 0.5 wt percent low density polyethylene. Powders were sintered in a Spark Plasma Sintering (SPS) furnace at 1600 °C, 1700 °C, 1750 °C, 1800 °C and 1850 °C using a modified sintering profile. This resulted in a uniform distribution of UO{sub 2} particles in a tungsten matrix with high densities, reaching 99.46% of theoretical for the sample sintered at 1850 °C. The powder process is described and the results of this study are given below.

  14. Non-uniform current distribution in a force-cooled superconductor under changing magnetic field

    International Nuclear Information System (INIS)

    Koizumi, Norikiyo

    2000-02-01

    Strands in a large current force-cooled superconductor, referred to a CICC (cable-in-conduit conductor) hereafter, are coated with formvar (insulated layer) or chrome plating (high resistive layer) to reduce coupling current loss due to magnetic field variation. The author first carried out an experiment of the large superconducting coil consisting of such CICCs for demonstration of their applicability to a large superconducting coil. These CICCs exhibited instability, i.e. the normal zone propagation with thermal runaway (quench), at 1/20 and 1/5 of the expected conductor critical currents, respectively. The author constructed the database of this instability and studies its reason through experimental and theoretical investigations and then finds such instability is caused as a result of non-uniform current distribution in the conductor. Joule heating loss at electrical connections at the ends of the conductor should be small. Therefore, the strands in the CICC are electrically connected from each other with low resistance there. Circulation current is induced in the loop composed of the strands electrically connected at the ends of the conductor if its leakage magnetic flux is not completely vanished. The non-uniform current distribution is caused as a result of superimposition of the circulation and transport currents. The strand carrying large current becomes the normal state when it reaches or approaches to its critical current. Thus, the strands are twisted in order to vanish the leakage magnetic flux. The instability due to the current imbalance was not observed in the middle-scale coil (an element coil, such as a single double-pancake, of a large superconducting coil) consisting of the conductor in which the formvar-coated strands were twisted as above-mentioned. Consequently, it was believed that the leakage magnetic flux could be vanished by the normal twisting. However, the magnetic field increases in a large coil as a result of piling element coils

  15. Comparative study of random and uniform models for the distribution of TRISO particles in HTR-10 fuel elements

    International Nuclear Information System (INIS)

    Rosales, J.; Perez, J.; Garcia, C.; Munnoz, A.; Lira, C. A. B. O.

    2015-01-01

    TRISO particles are the specific features of HTR-10 and generally HTGR reactors. Their heterogeneity and random arrangement in graphite matrix of these reactors create a significant modeling challenge. In the simulation of spherical fuel elements using MCNPX are usually created repetitive structures using uniform distribution models. The use of these repetitive structures introduces two major approaches: the non-randomness of the TRISO particles inside the pebbles and the intersection of the pebble surface with the TRISO particles. These approaches could affect significantly the multiplicative properties of the core. In order to study the influence of these approaches in the multiplicative properties was estimated the K inf value in one pebble with white boundary conditions using 4 different configurations regarding the distribution of the TRISO particles inside the pebble: uniform hexagonal model, cubic uniform model, cubic uniform without the effect of cutting and a random distribution model. It was studied the impact these models on core scale solving the problem B1, from the Benchmark Problems presented in a Coordinated Research Program of the IAEA. (Author)

  16. High quality uniform YBCO film growth by the metalorganic deposition using trifluoroacetates

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.S., E-mail: wangssh@tsinghua.edu.cn [Key Laboratory of Micro-nano Measurement, Manipulation and Physics (Beihang University), Ministry of Education, Beijing 100191 (China); Beijing Dingchen Superconducting Technology Co., Ltd., Beijing 100084 (China); Zhang, Z.L. [Key Laboratory of Micro-nano Measurement, Manipulation and Physics (Beihang University), Ministry of Education, Beijing 100191 (China); Wang, L. [Applied superconductivity research center, Department of Physics, Tsinghua University, Beijing 100084 (China); Gao, L.K.; Liu, J. [Beijing Dingchen Superconducting Technology Co., Ltd., Beijing 100084 (China)

    2017-03-15

    Highlights: • High quality double-sided YBCO films are fabricated on LaAlO3 substrates by TFA-MOD method with diameters up to 2 in. • Large area YBCO films were very uniform in microstructure and thickness distribution, an average inductive Jc in excess of 6 MA/cm{sup 2} and low R{sub s} (10 GHz) of 0.3 mΩ at 77 K were obtained. • It will greatly promoted the research and applications of large-area YBCO films by chemical solution method. - Abstract: A need exists for the large-area superconducting YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) films with high critical current density for microwave communication and/or electric power applications. Trifluoroacetic metalorganic (TFA-MOD) method is a promising low cost technique for large-scale production of YBCO films, because it does not need high vacuum device and is easily applicable to substrates of various shape and size. In this paper, double-sided YBCO films with maximum 2 in diameter were prepared on LaAlO{sub 3} substrates by TFA-MOD method. Inductive critical current densitiy J{sub c}, microwave surface resistance R{sub s}, as well as the microstructure were characterized. A newly homemade furnace system was used to epitaxially grown YBCO films, which can improve the uniformity of YBCO film significantly by gas supply and temperature distribution proper design. Results showed that the large area YBCO films were very uniform in microstructure and thickness distribution, an average inductive J{sub c} in excess of 6 MA/cm{sup 2} with uniform distribution, and low R{sub s} (10 GHz) below 0.3 mΩ at 77 K were obtained. Andthe film filter may be prepared to work at temperatures lower than 74 K. These results are very close to the highest value of YBCO films made by conventional vacuum method, so we show a very promising route for large-scale production of high quality large-area YBCO superconducting films at a lower cost.

  17. Uniformly distributed anatase TiO2 nanoparticles on graphene: Synthesis, characterization, and photocatalytic application

    International Nuclear Information System (INIS)

    Bai, Xue; Zhang, Xiaoyuan; Hua, Zulin; Ma, Wenqiang; Dai, Zhangyan; Huang, Xin; Gu, Haixin

    2014-01-01

    Highlights: • Uniform distributed TiO 2 nanoparticles on graphene by a modified method. • Reduced recombination rate of photogenerated electron–hole pairs. • Effective charge transfer from TiO 2 to graphene. • Better photocatalytic activity upon UV and visible irradiation. • A mechanism of bisphenol A degradation process is proposed. - Abstract: Graphene (GR)/TiO 2 nanocomposites are successfully synthesized using a simple and efficient hydrothermal method. Even-sized anatase TiO 2 nanoparticles are uniformly distributed on GR. The GR/TiO 2 nanocomposites exhibit an extended light absorption range and decreased electron–hole recombination rates. The photocatalytic activity of the as-prepared GR/TiO 2 nanocomposites for bisphenol A (BPA) degradation is investigated under UV (λ = 365 nm) and visible (λ ⩾ 400 nm) light irradiation. The results show that GR/TiO 2 nanocomposites have significantly higher photocatalytic activity than P25 (pure TiO 2 ). The large increase in photocatalytic activity is mostly attributed to effective charge transfer from TiO 2 nanoparticles to GR, which suppresses charge recombination during the photocatalytic process. After five successive cycles, the photodegradation activity of the GR/TiO 2 nanocomposites shows no significant decrease, which indicates that the nanocomposites are stable under UV and visible light. X-ray photoelectron spectroscopy (XPS) is used to investigate the chemical bonds of GR/TiO 2 nanocomposites before and after degradation to determine the degradation intermediate products of BPA under irradiation. A proposed degradation reaction pathway of BPA is also established. This study provides new insights into the fabrication and practical application of high-performance photocatalysts in wastewater treatment

  18. The importance of non-uniform dose-distribution in an organ

    International Nuclear Information System (INIS)

    Richmond, C.R.

    1975-01-01

    The recent revival of interest in the 'hot particle' problem, especially as regards particulate plutonium and other actinide elements in the lung, stimulated the preparation of this paper. Non-uniformity of dose-distribution has been of concern to standards-setting bodies and other groups such as the National Academy of Sciences and to health protectionists for many years. This paper reviews data from animal experiments that are used by some to implicate particulate plutonium as being especially hazardous to man. Other relevant biological data are also discussed. (author)

  19. Design of a collector shape for uniform flow distribution in microchannels

    International Nuclear Information System (INIS)

    Siddique, Ayyaz; Agrawal, Amit; Saha, Sandip K; Medhi, Bhaskar J; Singh, Anugrah

    2017-01-01

    The focus of this study is the design of a collector with the objective of achieving uniform flow in multiple parallel microchannels. This objective is achieved by understanding the limitations of current designs and a novel design is proposed, which is further carefully optimized. The existing collector shape considered is U-type, which is investigated numerically. The creation of a stagnation zone, growth of a boundary layer along the collector wall and low/high velocity zones in the collector are identified as the prime causes of flow maldistribution. A novel design, a dumbbell shape collector, is proposed to overcome the limitations of the earlier designs. The dumbbell shape is evaluated quantitatively and is found to perform better than all existing shapes. This dumbbell shape collector provides a uniform flow distribution with less than 0.4% relative difference from the average flow rate in different channels, which is substantially better than existing collectors with 2.3% relative difference from the average flow rate for Re ch   =  32. The uniformity is further confirmed using micro-particle image velocimetry measurements. The dumbbell shape collector is generalized and optimized to cater to heat sinks of different dimensions and to broaden its applicability in both micro and macro dimensions. (paper)

  20. Reactivity effect of non-uniformly distributed fuel in fuel solution systems

    International Nuclear Information System (INIS)

    Hirano, Yasushi; Yamane, Yoshihiro; Nishina, Kojiro; Mitsuhashi, Ishi.

    1991-01-01

    A numerical method to determine the optimal fuel distribution for minimum critical mass, or maximum k-effective, is developed using the Maximum Principle in order to evaluate the maximum effect of non-uniformly distributed fuel on reactivity. This algorithm maximizes the Hamiltonian directly by an iterative method under a certain constraint-the maintenance of criticality or total fuel mass. It ultimately reaches the same optimal state of a flattened fuel importance distribution as another algorithm by Dam based on perturbation theory. This method was applied to two kinds of spherical cores with water reflector in the simulating reprocessing facility. In the slightly-enriched uranyl nitrate solution core, the minimum critical mass decreased by less than 1% at the optimal moderation state. In the plutonium nitrate solution core, the k-effective increment amounted up to 4.3% Δk within the range of present study. (author)

  1. Scalable and Fully Distributed Localization in Large-Scale Sensor Networks

    Directory of Open Access Journals (Sweden)

    Miao Jin

    2017-06-01

    Full Text Available This work proposes a novel connectivity-based localization algorithm, well suitable for large-scale sensor networks with complex shapes and a non-uniform nodal distribution. In contrast to current state-of-the-art connectivity-based localization methods, the proposed algorithm is highly scalable with linear computation and communication costs with respect to the size of the network; and fully distributed where each node only needs the information of its neighbors without cumbersome partitioning and merging process. The algorithm is theoretically guaranteed and numerically stable. Moreover, the algorithm can be readily extended to the localization of networks with a one-hop transmission range distance measurement, and the propagation of the measurement error at one sensor node is limited within a small area of the network around the node. Extensive simulations and comparison with other methods under various representative network settings are carried out, showing the superior performance of the proposed algorithm.

  2. An efficient method based on the uniformity principle for synthesis of large-scale heat exchanger networks

    International Nuclear Information System (INIS)

    Zhang, Chunwei; Cui, Guomin; Chen, Shang

    2016-01-01

    Highlights: • Two dimensionless uniformity factors are presented to heat exchange network. • The grouping of process streams reduces the computational complexity of large-scale HENS problems. • The optimal sub-network can be obtained by Powell particle swarm optimization algorithm. • The method is illustrated by a case study involving 39 process streams, with a better solution. - Abstract: The optimal design of large-scale heat exchanger networks is a difficult task due to the inherent non-linear characteristics and the combinatorial nature of heat exchangers. To solve large-scale heat exchanger network synthesis (HENS) problems, two dimensionless uniformity factors to describe the heat exchanger network (HEN) uniformity in terms of the temperature difference and the accuracy of process stream grouping are deduced. Additionally, a novel algorithm that combines deterministic and stochastic optimizations to obtain an optimal sub-network with a suitable heat load for a given group of streams is proposed, and is named the Powell particle swarm optimization (PPSO). As a result, the synthesis of large-scale heat exchanger networks is divided into two corresponding sub-parts, namely, the grouping of process streams and the optimization of sub-networks. This approach reduces the computational complexity and increases the efficiency of the proposed method. The robustness and effectiveness of the proposed method are demonstrated by solving a large-scale HENS problem involving 39 process streams, and the results obtained are better than those previously published in the literature.

  3. Controllable chemical vapor deposition of large area uniform nanocrystalline graphene directly on silicon dioxide

    DEFF Research Database (Denmark)

    Sun, Jie; Lindvall, Niclas; Cole, Matthew T.

    2012-01-01

    Metal-catalyst-free chemical vapor deposition (CVD) of large area uniform nanocrystalline graphene on oxidized silicon substrates is demonstrated. The material grows slowly, allowing for thickness control down to monolayer graphene. The as-grown thin films are continuous with no observable pinholes...

  4. Strain distributions in nano-onions with uniform and non-uniform compositions

    International Nuclear Information System (INIS)

    Duan, H L; Karihaloo, B L; Wang, J; Yi, X

    2006-01-01

    Nano-onions are ellipsoidal or spherical particles consisting of a core surrounded by concentric shells of nanometre size. Nano-onions produced by self-assembly and colloidal techniques have different structures and compositions, and thus differ in the state of strains. The mismatch of the thermal expansion coefficients and lattice constants between neighbouring shells induces stress/strain fields in the core and shells, which in turn affect their physical/mechanical properties and/or the properties of the composites containing them. In this paper, the strains in embedded and free-standing nano-onions with uniform and non-uniform compositions are studied in detail. It is found that the strains in the nano-onions can be modified by adjusting their compositions and structures. The results are useful for the band structure engineering of semiconductor nano-onions

  5. Three-dimensional reconstruction of a radionuclide distribution within a medium of uniform coefficient of attenuation

    International Nuclear Information System (INIS)

    Diaz, J.E.

    1982-01-01

    The non-invasive, fully three-dimensional reconstruction of a radionuclide distribution is studied. The problem is considered in ideal form. Several solutions, ranging from the completely analytical to the completely graphical, are presented for both the non-attenuated and uniformly attenuated cases. A function is defined which, if enacted as a response to each detected photon, will yield, upon superposition, a faithful reconstruction of the radionuclide density. Two and three-dimensional forms of this functions are defined for both the non-attenuated and uniformly attenuated case

  6. A numerical model to evaluate the flow distribution in a large solar collector field

    DEFF Research Database (Denmark)

    Bava, Federico; Dragsted, Janne; Furbo, Simon

    2017-01-01

    This study presents a numerical model to evaluate the flow distribution in a large solar collector field, with solar collectors connected both in series and in parallel. The boundary conditions of the systems, such as flow rate, temperature, fluid type and layout of the collector field can...... be easily changed in the model. The model was developed in Matlab and the calculated pressure drop and flow distribution were compared with measurements from a solar collector field. A good agreement between model and measurements was found. The model was then used to study the flow distribution...... in different conditions. Balancing valves proved to be an effective way to achieve uniform flow distribution also in conditions different from those for which the valves were regulated. For small solar collector fields with limited number of collector rows connected in parallel, balancing valves...

  7. Hydrodynamic characteristics of steady magnetic fluid flow in a straight tube by taking into account the non-uniform distribution of mass concentration

    International Nuclear Information System (INIS)

    Shuchi, S.; Shimada, K.; Kamiyama, S.; Yamaguchi, H.

    2002-01-01

    We clarify numerically the wall friction coefficient, the distributions of velocity and shear rate, and the number of aggregated particles on steady magnetic fluid flow in a straight tube by taking into account the non-uniform distribution of mass concentration (DMC). Also the effect of DMC is clarified under the uniform and non-uniform transverse steady magnetic field. In comparison with the published data, the numerical results show good agreement with the experimental data

  8. Reliable solution processed planar perovskite hybrid solar cells with large-area uniformity by chloroform soaking and spin rinsing induced surface precipitation

    Directory of Open Access Journals (Sweden)

    Yann-Cherng Chern

    2015-08-01

    Full Text Available A solvent soaking and rinsing method, in which the solvent was allowed to soak all over the surface followed by a spinning for solvent draining, was found to produce perovskite layers with high uniformity on a centimeter scale and with much improved reliability. Besides the enhanced crystallinity and surface morphology due to the rinsing induced surface precipitation that constrains the grain growth underneath in the precursor films, large-area uniformity with film thickness determined exclusively by the rotational speed of rinsing spinning for solvent draining was observed. With chloroform as rinsing solvent, highly uniform and mirror-like perovskite layers of area as large as 8 cm × 8 cm were produced and highly uniform planar perovskite solar cells with power conversion efficiency of 10.6 ± 0.2% as well as much prolonged lifetime were obtained. The high uniformity and reliability observed with this solvent soaking and rinsing method were ascribed to the low viscosity of chloroform as well as its feasibility of mixing with the solvent used in the precursor solution. Moreover, since the surface precipitation forms before the solvent draining, this solvent soaking and rinsing method may be adapted to spinless process and be compatible with large-area and continuous production. With the large-area uniformity and reliability for the resultant perovskite layers, this chloroform soaking and rinsing approach may thus be promising for the mass production and commercialization of large-area perovskite solar cells.

  9. Global solubility of the three-dimensional Navier-Stokes equations with uniformly large initial vorticity

    International Nuclear Information System (INIS)

    Makhalov, A S; Nikolaenko, V P

    2003-01-01

    This paper is a survey of results concerning the three-dimensional Navier-Stokes and Euler equations with initial data characterized by uniformly large vorticity. The existence of regular solutions of the three-dimensional Navier-Stokes equations on an unbounded time interval is proved for large initial data both in R 3 and in bounded cylindrical domains. Moreover, the existence of smooth solutions on large finite time intervals is established for the three-dimensional Euler equations. These results are obtained without additional assumptions on the behaviour of solutions for t>0. Any smooth solution is not close to any two-dimensional manifold. Our approach is based on the computation of singular limits of rapidly oscillating operators, non-linear averaging, and a consideration of the mutual absorption of non-linear oscillations of the vorticity field. The use of resonance conditions, methods from the theory of small divisors, and non-linear averaging of almost periodic functions leads to the limit resonant Navier-Stokes equations. Global solubility of these equations is proved without any conditions on the three-dimensional initial data. The global regularity of weak solutions of three-dimensional Navier-Stokes equations with uniformly large vorticity at t=0 is proved by using the regularity of weak solutions and the strong convergence

  10. Uniform, dense arrays of vertically aligned, large-diameter single-walled carbon nanotubes.

    Science.gov (United States)

    Han, Zhao Jun; Ostrikov, Kostya

    2012-04-04

    Precisely controlled reactive chemical vapor synthesis of highly uniform, dense arrays of vertically aligned single-walled carbon nanotubes (SWCNTs) using tailored trilayered Fe/Al(2)O(3)/SiO(2) catalyst is demonstrated. More than 90% population of thick nanotubes (>3 nm in diameter) can be produced by tailoring the thickness and microstructure of the secondary catalyst supporting SiO(2) layer, which is commonly overlooked. The proposed model based on the atomic force microanalysis suggests that this tailoring leads to uniform and dense arrays of relatively large Fe catalyst nanoparticles on which the thick SWCNTs nucleate, while small nanotubes and amorphous carbon are effectively etched away. Our results resolve a persistent issue of selective (while avoiding multiwalled nanotubes and other carbon nanostructures) synthesis of thick vertically aligned SWCNTs whose easily switchable thickness-dependent electronic properties enable advanced applications in nanoelectronic, energy, drug delivery, and membrane technologies.

  11. Age-dependent effective doses for radionuclides uniformly distributed in air

    International Nuclear Information System (INIS)

    Hung, Tran Van

    2014-01-01

    Age-dependent effective doses for external exposure to photons emitted by radionuclides uniformly distributed in air are reported. The calculations were performed for 160 radionuclides, which are important for safety assessment of nuclear facilities. The energies and intensities of photons emitted from radionuclides were taken from the decay data DECDC used for dose calculations. The results are tabulated in the form of effective dose per unit concentration and time (Sv per Bq s m -3 ) for 6 age groups: newborn, 1, 5, 10 and 15 years-old and adult. The effective doses for the adult are also compared to values given in the literature.

  12. Large-Area Synthesis of High-Quality Uniform Few-Layer MoTe2.

    Science.gov (United States)

    Zhou, Lin; Xu, Kai; Zubair, Ahmad; Liao, Albert D; Fang, Wenjing; Ouyang, Fangping; Lee, Yi-Hsien; Ueno, Keiji; Saito, Riichiro; Palacios, Tomás; Kong, Jing; Dresselhaus, Mildred S

    2015-09-23

    The controlled synthesis of large-area, atomically thin molybdenum ditelluride (MoTe2) crystals is crucial for its various applications based on the attractive properties of this emerging material. In this work, we developed a chemical vapor deposition synthesis to produce large-area, uniform, and highly crystalline few-layer 2H and 1T' MoTe2 films. It was found that these two different phases of MoTe2 can be grown depending on the choice of Mo precursor. Because of the highly crystalline structure, the as-grown few-layer 2H MoTe2 films display electronic properties that are comparable to those of mechanically exfoliated MoTe2 flakes. Our growth method paves the way for the large-scale application of MoTe2 in high-performance nanoelectronics and optoelectronics.

  13. Experimental study on the CHF in uniformly and non-uniformly heated vertical annuli

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Se Young; Moon, Sang Ki; Chung, Heung June; Park, Jong Kuk; Kim, Bok Deuk; Youn, Young Jung; Chung, Moon Ki

    2001-09-01

    Up to now, KAERI has performed critical heat flux experiments in water under zero-flow and low-flow conditions using a RCS CHF loop facility with uniformly and non-uniformly heated vertical annulus. Since the existing CHF experiments were mainly performed under low-pressure conditions, we performed the CHF experiment to investigate the pressure effect on the CHF under zero-flow and low-flow conditions for a wide range of system pressures. Also, two vertical annuli with the same geometry have been used to investigate the axial heat flux distributions on the CHF. This report summarizes the experimental results and provides the CHF data that can be used for the development for CHF correlation and a thermal hydraulic analysis code. The CHF data have been collected for system pressures ranging from 0.57 to 15.15 MPa, mass flux 0 and from 200 to 650 kg/m2s, inlet subcooling from 75 to 360 kJ/kg and exit quality from 0.07 to 0.57. At low-flow conditions, the total number of data are 242 and 290 with uniformly heated- and non-uniformly heated test sections, respectively. 41 and 94 CHF data are generated with uniformly heated- and non-uniformly heated test sections, respectively, in zero-flow CHF experiments that are performed by blocking test section bottoms. The CHF experiment result shows that the effects of system pressure, mass flux and inlet subcooling are consistent with conventional understandings and similar to those for round tubes. The behavior of the CHF is relatively complex at low pressures. Also, the effects of axial heat flux profile are large at low-pressure conditions.

  14. Experimental study on the CHF in uniformly and non-uniformly heated vertical annuli

    International Nuclear Information System (INIS)

    Chun, Se Young; Moon, Sang Ki; Chung, Heung June; Park, Jong Kuk; Kim, Bok Deuk; Youn, Young Jung; Chung, Moon Ki

    2001-09-01

    Up to now, KAERI has performed critical heat flux experiments in water under zero-flow and low-flow conditions using a RCS CHF loop facility with uniformly and non-uniformly heated vertical annulus. Since the existing CHF experiments were mainly performed under low-pressure conditions, we performed the CHF experiment to investigate the pressure effect on the CHF under zero-flow and low-flow conditions for a wide range of system pressures. Also, two vertical annuli with the same geometry have been used to investigate the axial heat flux distributions on the CHF. This report summarizes the experimental results and provides the CHF data that can be used for the development for CHF correlation and a thermal hydraulic analysis code. The CHF data have been collected for system pressures ranging from 0.57 to 15.15 MPa, mass flux 0 and from 200 to 650 kg/m2s, inlet subcooling from 75 to 360 kJ/kg and exit quality from 0.07 to 0.57. At low-flow conditions, the total number of data are 242 and 290 with uniformly heated- and non-uniformly heated test sections, respectively. 41 and 94 CHF data are generated with uniformly heated- and non-uniformly heated test sections, respectively, in zero-flow CHF experiments that are performed by blocking test section bottoms. The CHF experiment result shows that the effects of system pressure, mass flux and inlet subcooling are consistent with conventional understandings and similar to those for round tubes. The behavior of the CHF is relatively complex at low pressures. Also, the effects of axial heat flux profile are large at low-pressure conditions

  15. Measurement of luminance and color uniformity of displays using the large-format scanner

    Science.gov (United States)

    Mazikowski, Adam

    2017-08-01

    Uniformity of display luminance and color is important for comfort and good perception of the information presented on the display. Although display technology has developed and improved a lot over the past years, different types of displays still present a challenge in selected applications, e.g. in medical use or in case of multi-screen installations. A simplified 9-point method of determining uniformity does not always produce satisfactory results, so a different solution is proposed in the paper. The developed system consists of the large-format X-Y-Z ISEL scanner (isel Germany AG), Konica Minolta high sensitivity spot photometer-colorimeter (e.g. CS-200, Konica Minolta, Inc.) and PC computer. Dedicated software in LabView environment for control of the scanner, transfer the measured data to the computer, and visualization of measurement results was also prepared. Based on the developed setup measurements of plasma display and LCD-LED display were performed. A heavily wornout plasma TV unit, with several artifacts visible was selected. These tests show the advantages and drawbacks of described scanning method with comparison with 9-point simplified uniformity determining method.

  16. Workflow management in large distributed systems

    International Nuclear Information System (INIS)

    Legrand, I; Newman, H; Voicu, R; Dobre, C; Grigoras, C

    2011-01-01

    The MonALISA (Monitoring Agents using a Large Integrated Services Architecture) framework provides a distributed service system capable of controlling and optimizing large-scale, data-intensive applications. An essential part of managing large-scale, distributed data-processing facilities is a monitoring system for computing facilities, storage, networks, and the very large number of applications running on these systems in near realtime. All this monitoring information gathered for all the subsystems is essential for developing the required higher-level services—the components that provide decision support and some degree of automated decisions—and for maintaining and optimizing workflow in large-scale distributed systems. These management and global optimization functions are performed by higher-level agent-based services. We present several applications of MonALISA's higher-level services including optimized dynamic routing, control, data-transfer scheduling, distributed job scheduling, dynamic allocation of storage resource to running jobs and automated management of remote services among a large set of grid facilities.

  17. Workflow management in large distributed systems

    Science.gov (United States)

    Legrand, I.; Newman, H.; Voicu, R.; Dobre, C.; Grigoras, C.

    2011-12-01

    The MonALISA (Monitoring Agents using a Large Integrated Services Architecture) framework provides a distributed service system capable of controlling and optimizing large-scale, data-intensive applications. An essential part of managing large-scale, distributed data-processing facilities is a monitoring system for computing facilities, storage, networks, and the very large number of applications running on these systems in near realtime. All this monitoring information gathered for all the subsystems is essential for developing the required higher-level services—the components that provide decision support and some degree of automated decisions—and for maintaining and optimizing workflow in large-scale distributed systems. These management and global optimization functions are performed by higher-level agent-based services. We present several applications of MonALISA's higher-level services including optimized dynamic routing, control, data-transfer scheduling, distributed job scheduling, dynamic allocation of storage resource to running jobs and automated management of remote services among a large set of grid facilities.

  18. Strong Law of Large Numbers for Hidden Markov Chains Indexed by an Infinite Tree with Uniformly Bounded Degrees

    Directory of Open Access Journals (Sweden)

    Huilin Huang

    2014-01-01

    Full Text Available We study strong limit theorems for hidden Markov chains fields indexed by an infinite tree with uniformly bounded degrees. We mainly establish the strong law of large numbers for hidden Markov chains fields indexed by an infinite tree with uniformly bounded degrees and give the strong limit law of the conditional sample entropy rate.

  19. Uniform Sampling Table Method and its Applications II--Evaluating the Uniform Sampling by Experiment.

    Science.gov (United States)

    Chen, Yibin; Chen, Jiaxi; Chen, Xuan; Wang, Min; Wang, Wei

    2015-01-01

    A new method of uniform sampling is evaluated in this paper. The items and indexes were adopted to evaluate the rationality of the uniform sampling. The evaluation items included convenience of operation, uniformity of sampling site distribution, and accuracy and precision of measured results. The evaluation indexes included operational complexity, occupation rate of sampling site in a row and column, relative accuracy of pill weight, and relative deviation of pill weight. They were obtained from three kinds of drugs with different shape and size by four kinds of sampling methods. Gray correlation analysis was adopted to make the comprehensive evaluation by comparing it with the standard method. The experimental results showed that the convenience of uniform sampling method was 1 (100%), odds ratio of occupation rate in a row and column was infinity, relative accuracy was 99.50-99.89%, reproducibility RSD was 0.45-0.89%, and weighted incidence degree exceeded the standard method. Hence, the uniform sampling method was easy to operate, and the selected samples were distributed uniformly. The experimental results demonstrated that the uniform sampling method has good accuracy and reproducibility, which can be put into use in drugs analysis.

  20. Analysis and Optimization for Uniformity of Magnetic Field Driving the Giant Magnetostriction

    International Nuclear Information System (INIS)

    Wang, L; Ye, H; Liu, Y T; Yao, S M

    2006-01-01

    Giant magnetostriction actuator based on material Tb0.27Dy0.73Fe2 and electromagnetic transform has characteristics of high frequency response, large output power and etc, but it has a high demand for the uniformity of magnetic field driver and magnetic intensity. Object to the problem, a multi-scale external concavity structure is proposed, by means of inducting the hollow column coil structure, building the model of coil magnetic distribution and analyzing by finite element analysis method. The analysis results show that uniformity of the model magnetic field is dependent upon magnetic intensity and scales, and the boundary condition of material. As the scale increases, magnetic uniformity is enhanced, but the magnetic intensity is decreased. Taking consideration both of magnetic field distribution and magnetic intensity, threescale structure is determined as optimum structure

  1. Non-uniformly sampled grids in double pole coordinate system for freeform reflector construction

    Science.gov (United States)

    Ma, Donglin; Pacheco, Shaun; Feng, Zexin; Liang, Rongguang

    2015-08-01

    We propose a new method to design freeform reflectors by nonuniformly sampling the source intensity distribution in double pole coordinate system. In double pole coordinate system, there is no pole for the whole hemisphere because both poles of the spherical coordinate system are moved to southernmost point of the sphere and overlapped together. With symmetric definition of both angular coordinates in the modified double pole coordinate system, a better match between the source intensity distribution and target irradiance distribution can be achieved for reflectors with large acceptance solid angle, leading to higher light efficiency and better uniformity on the target surface. With non-uniform sampling of the source intensity, we can design circular freeform reflector to obtain uniform rectangular illumination pattern. Aided by the feedback optimization, the freeform reflector can achieve the collection efficiency for ideal point source over 0.7 and relative standard deviation (RSD) less than 0.1.

  2. Novel Composite Powders with Uniform TiB2 Nano-Particle Distribution for 3D Printing

    Directory of Open Access Journals (Sweden)

    Mengxing Chen

    2017-03-01

    Full Text Available It is reported that the ductility and strength of a metal matrix composite could be concurrently improved if the reinforcing particles were of the size of nanometers and distributed uniformly. In this paper, we revealed that gas atomization solidification could effectively disperse TiB2 nanoparticles in the Al alloy matrix due to its fast cooling rate and the coherent orientation relationship between TiB2 particles and α-Al. Besides, nano-TiB2 led to refined equiaxed grain structures. Furthermore, the composite powders with uniformly embedded nano-TiB2 showed improved laser absorptivity. The novel composite powders are well suited for selective laser melting.

  3. Large scale network-centric distributed systems

    CERN Document Server

    Sarbazi-Azad, Hamid

    2014-01-01

    A highly accessible reference offering a broad range of topics and insights on large scale network-centric distributed systems Evolving from the fields of high-performance computing and networking, large scale network-centric distributed systems continues to grow as one of the most important topics in computing and communication and many interdisciplinary areas. Dealing with both wired and wireless networks, this book focuses on the design and performance issues of such systems. Large Scale Network-Centric Distributed Systems provides in-depth coverage ranging from ground-level hardware issu

  4. Large-scale uniform bilayer graphene prepared by vacuum graphitization of 6H-SiC(0001) substrates

    Science.gov (United States)

    Wang, Qingyan; Zhang, Wenhao; Wang, Lili; He, Ke; Ma, Xucun; Xue, Qikun

    2013-03-01

    We report on the preparation of large-scale uniform bilayer graphenes on nominally flat Si-polar 6H-SiC(0001) substrates by flash annealing in ultrahigh vacuum. The resulting graphenes have a single thickness of one bilayer and consist of regular terraces separated by the triple SiC bilayer steps on the 6H-SiC(0001) substrates. In situ scanning tunneling microscopy reveals that suppression of pit formation on terraces and uniformity of SiC decomposition at step edges are the key factors to the uniform thickness. By studying the surface morphologies prepared under different annealing rates, it is found that the annealing rate is directly related to SiC decomposition, diffusion of the released Si/C atoms and strain relaxation, which together determine the final step structure and density of defects.

  5. Roles of ethylene glycol solvent and polymers in preparing uniformly distributed MgO nanoparticles

    Directory of Open Access Journals (Sweden)

    Chunxi Hai

    2017-06-01

    Full Text Available This study focus on specifying the roles of solvent ethylene glycol (EG and polymers for synthesis of uniformly distributed magnesium oxide (MgO nanoparticles with average crystallite size of around 50 nm through a modified polyol method. Based on different characterization results, it was concluded that, Mg2+ ions was precipitated by the −OH and CO32− ions decomposed from urea in ethylene glycol (EG medium (CO(NH22 → NH3 + HNCO, HNCO + H2O → NH3 + CO2, thus forming well crystallized Mg5(CO34(OH2 (H2O4 precursor which could be converted to MgO by calcination. Surface protectors PEG and PVP have no obvious influences on cyrtsal structure, morphology and size uniformity of as-prepared precursors and target MgO nanoparticles. In comparison with polymers PEG and PVP, solvent EG plays an important role in controlling the morphology and diameter uniformity of MgO nanoparticles.

  6. Strong Law of Large Numbers for Countable Markov Chains Indexed by an Infinite Tree with Uniformly Bounded Degree

    Directory of Open Access Journals (Sweden)

    Bao Wang

    2014-01-01

    Full Text Available We study the strong law of large numbers for the frequencies of occurrence of states and ordered couples of states for countable Markov chains indexed by an infinite tree with uniformly bounded degree, which extends the corresponding results of countable Markov chains indexed by a Cayley tree and generalizes the relative results of finite Markov chains indexed by a uniformly bounded tree.

  7. Non-uniform Solar Temperature Field on Large Aperture, Fully-Steerable Telescope Structure

    Science.gov (United States)

    Liu, Yan

    2016-09-01

    In this study, a 110-m fully steerable radio telescope was used as an analysis platform and the integral parametric finite element model of the antenna structure was built in the ANSYS thermal analysis module. The boundary conditions of periodic air temperature, solar radiation, long-wave radiation shadows of the surrounding environment, etc. were computed at 30 min intervals under a cloudless sky on a summer day, i.e., worstcase climate conditions. The transient structural temperatures were then analyzed under a period of several days of sunshine with a rational initial structural temperature distribution until the whole set of structural temperatures converged to the results obtained the day before. The non-uniform temperature field distribution of the entire structure and the main reflector surface RMS were acquired according to changes in pitch and azimuth angle over the observation period. Variations in the solar cooker effect over time and spatial distributions in the secondary reflector were observed to elucidate the mechanism of the effect. The results presented here not only provide valuable realtime data for the design, construction, sensor arrangement and thermal deformation control of actuators but also provide a troubleshooting reference for existing actuators.

  8. The characteristics on dose distribution of a large field

    International Nuclear Information System (INIS)

    Lee, Sang Rok; Jeong, Deok Yang; Lee, Btiung Koo; Kwon, Young Ho

    2003-01-01

    In special cases of Total Body Irradiation(TBI), Half Body Irradiation(HBI), Non-Hodgkin's lymphoma, E-Wing's sarcoma, lymphosarcoma and neuroblastoma a large field can be used clinically. The dose distribution of a large field can use the measurement result which gets from dose distribution of a small field (standard SSD 100 cm, size of field under 40 x 40 cm 2 ) in the substitution which always measures in practice and it will be able to calibrate. With only the method of simple calculation, it is difficult to know the dose and its uniformity of actual body region by various factor of scatter radiation. In this study, using Multidata Water Phantom from standard SSD 100 cm according to the size change of field, it measures the basic parameter (PDD,TMR,Output,Sc,Sp) From SSD 180 cm (phantom is to the bottom vertically) according to increasing of a field, it measures a basic parameter. From SSD 350 cm (phantom is to the surface of a wall, using small water phantom. which includes mylar capable of horizontal beam's measurement) it measured with the same method and compared with each other. In comparison with the standard dose data, parameter which measures between SSD 180 cm and 350 cm, it turned out there was little difference. The error range is not up to extent of the experimental error. In order to get the accurate data, it dose measures from anthropomorphous phantom or for this objective the dose measurement which is the possibility of getting the absolute value which uses the unlimited phantom that is devised especially is demanded. Additionally, it needs to consider ionization chamber use of small volume and stem effect of cable by a large field.

  9. Numerical research on natural convection in molten salt reactor with non-uniformly distributed volumetric heat generation

    International Nuclear Information System (INIS)

    Qian Libo; Qiu Suizheng; Zhang Dalin; Su Guanghui; Tian Wenxi

    2010-01-01

    Molten salt reactor is one of the six Generation IV systems capable of breeding and transmutation of actinides and long-lived fission products, which uses the liquid molten salt as the fuel solvent, coolant and heat generation simultaneously. The present work presents a numerical investigation on natural convection with non-uniform heat generation through which the heat generated by the fluid fuel is removed out of the core region when the reactor is under post-accident condition or zero-power condition. The two-group neutron diffusion equation is applied to calculated neutron flux distribution, which leads to non-uniform heat generation. The SIMPLER algorithm is used to calculate natural convective heat transfer rate with isothermal or adiabatic rigid walls. These two models are coupled through the temperature field and heat sources. The peculiarities of natural convection with non-uniform heat generation are investigated in a range of Ra numbers (10 3 ∼ 10 7 ) for the laminar regime of fluid motion. In addition, the numerical results are also compared with those containing uniform heat generation.

  10. Size Distribution Imaging by Non-Uniform Oscillating-Gradient Spin Echo (NOGSE MRI.

    Directory of Open Access Journals (Sweden)

    Noam Shemesh

    Full Text Available Objects making up complex porous systems in Nature usually span a range of sizes. These size distributions play fundamental roles in defining the physicochemical, biophysical and physiological properties of a wide variety of systems - ranging from advanced catalytic materials to Central Nervous System diseases. Accurate and noninvasive measurements of size distributions in opaque, three-dimensional objects, have thus remained long-standing and important challenges. Herein we describe how a recently introduced diffusion-based magnetic resonance methodology, Non-Uniform-Oscillating-Gradient-Spin-Echo (NOGSE, can determine such distributions noninvasively. The method relies on its ability to probe confining lengths with a (length6 parametric sensitivity, in a constant-time, constant-number-of-gradients fashion; combined, these attributes provide sufficient sensitivity for characterizing the underlying distributions in μm-scaled cellular systems. Theoretical derivations and simulations are presented to verify NOGSE's ability to faithfully reconstruct size distributions through suitable modeling of their distribution parameters. Experiments in yeast cell suspensions - where the ground truth can be determined from ancillary microscopy - corroborate these trends experimentally. Finally, by appending to the NOGSE protocol an imaging acquisition, novel MRI maps of cellular size distributions were collected from a mouse brain. The ensuing micro-architectural contrasts successfully delineated distinctive hallmark anatomical sub-structures, in both white matter and gray matter tissues, in a non-invasive manner. Such findings highlight NOGSE's potential for characterizing aberrations in cellular size distributions upon disease, or during normal processes such as development.

  11. Modeling of a Pouch Lithium Ion Battery Using a Distributed Parameter Equivalent Circuit for Internal Non-Uniformity Analysis

    Directory of Open Access Journals (Sweden)

    Dafen Chen

    2016-10-01

    Full Text Available A battery model that has the capability of analyzing the internal non-uniformity of local state variables, including the state of charge (SOC, temperature and current density, is proposed in this paper. The model is built using a set of distributed parameter equivalent circuits. In order to validate the accuracy of the model, a customized battery with embedded T-type thermocouple sensors inside the battery is tested. The simulated temperature conforms well with the measured temperature at each test point, and the maximum difference is less than 1 °C. Then, the model is applied to analyze the evolution processes of local state variables’ distribution inside the battery during the discharge process. The simulation results demonstrate drastic distribution changes of the local state variables inside the battery during the discharge process. The internal non-uniformity is originally caused by the resistance of positive and negative foils, while also influenced by the change rate of open circuit voltage and the total resistance of the battery. Hence, the factors that affect the distribution of the local state variables are addressed.

  12. New reversing freeform lens design method for LED uniform illumination with extended source and near field

    Science.gov (United States)

    Zhao, Zhili; Zhang, Honghai; Zheng, Huai; Liu, Sheng

    2018-03-01

    In light-emitting diode (LED) array illumination (e.g. LED backlighting), obtainment of high uniformity in the harsh condition of the large distance height ratio (DHR), extended source and near field is a key as well as challenging issue. In this study, we present a new reversing freeform lens design algorithm based on the illuminance distribution function (IDF) instead of the traditional light intensity distribution, which allows uniform LED illumination in the above mentioned harsh conditions. IDF of freeform lens can be obtained by the proposed mathematical method, considering the effects of large DHR, extended source and near field target at the same time. In order to prove the claims, a slim direct-lit LED backlighting with DHR equal to 4 is designed. In comparison with the traditional lenses, illuminance uniformity of LED backlighting with the new lens increases significantly from 0.45 to 0.84, and CV(RMSE) decreases dramatically from 0.24 to 0.03 in the harsh condition. Meanwhile, luminance uniformity of LED backlighting with the new lens is obtained as high as 0.92 at the condition of extended source and near field. This new method provides a practical and effective way to solve the problem of large DHR, extended source and near field for LED array illumination.

  13. A Smart Cage With Uniform Wireless Power Distribution in 3D for Enabling Long-Term Experiments With Freely Moving Animals.

    Science.gov (United States)

    Mirbozorgi, S Abdollah; Bahrami, Hadi; Sawan, Mohamad; Gosselin, Benoit

    2016-04-01

    This paper presents a novel experimental chamber with uniform wireless power distribution in 3D for enabling long-term biomedical experiments with small freely moving animal subjects. The implemented power transmission chamber prototype is based on arrays of parallel resonators and multicoil inductive links, to form a novel and highly efficient wireless power transmission system. The power transmitter unit includes several identical resonators enclosed in a scalable array of overlapping square coils which are connected in parallel to provide uniform power distribution along x and y. Moreover, the proposed chamber uses two arrays of primary resonators, facing each other, and connected in parallel to achieve uniform power distribution along the z axis. Each surface includes 9 overlapped coils connected in parallel and implemented into two layers of FR4 printed circuit board. The chamber features a natural power localization mechanism, which simplifies its implementation and ease its operation by avoiding the need for active detection and control mechanisms. A single power surface based on the proposed approach can provide a power transfer efficiency (PTE) of 69% and a power delivered to the load (PDL) of 120 mW, for a separation distance of 4 cm, whereas the complete chamber prototype provides a uniform PTE of 59% and a PDL of 100 mW in 3D, everywhere inside the chamber with a size of 27×27×16 cm(3).

  14. Distribution uniformity of laser-accelerated proton beams

    Science.gov (United States)

    Zhu, Jun-Gao; Zhu, Kun; Tao, Li; Xu, Xiao-Han; Lin, Chen; Ma, Wen-Jun; Lu, Hai-Yang; Zhao, Yan-Ying; Lu, Yuan-Rong; Chen, Jia-Er; Yan, Xue-Qing

    2017-09-01

    Compared with conventional accelerators, laser plasma accelerators can generate high energy ions at a greatly reduced scale, due to their TV/m acceleration gradient. A compact laser plasma accelerator (CLAPA) has been built at the Institute of Heavy Ion Physics at Peking University. It will be used for applied research like biological irradiation, astrophysics simulations, etc. A beamline system with multiple quadrupoles and an analyzing magnet for laser-accelerated ions is proposed here. Since laser-accelerated ion beams have broad energy spectra and large angular divergence, the parameters (beam waist position in the Y direction, beam line layout, drift distance, magnet angles etc.) of the beamline system are carefully designed and optimised to obtain a radially symmetric proton distribution at the irradiation platform. Requirements of energy selection and differences in focusing or defocusing in application systems greatly influence the evolution of proton distributions. With optimal parameters, radially symmetric proton distributions can be achieved and protons with different energy spread within ±5% have similar transverse areas at the experiment target. Supported by National Natural Science Foundation of China (11575011, 61631001) and National Grand Instrument Project (2012YQ030142)

  15. Liquid metal flow in a large-radius elbow with a uniform magnetic fluid

    International Nuclear Information System (INIS)

    Moon, T.J.; Walker, J.S.

    1988-07-01

    This paper treats the liquid-metal flow in an elbow between two straight, rectangular ducts. There is a uniform magnetic field in the plane of the elbow. The duct has thin, electrically conducting walls. The Hartmann number and the interaction parameter are assumed to be large, while the magnetic Reynolds number is assumed to be small. Solutions for the velocity at each cross section of the elbow and for the pressure drop due to three-dimensional effects are presented. 10 refs., 5 figs

  16. Controlling of density uniformity of polyacrylate foams

    International Nuclear Information System (INIS)

    Shan Wenwen; Yuan Baohe; Wang Yanhong; Xu Jiayun; Zhang Lin

    2010-01-01

    The density non-uniformity existing in most low-density foams will affect performance of the foams. The trimethylolpropane trimethacrylate (TMPTA) foam targets were prepared and controlling methods of the foams, density uniformity were explored together with its forming mechanism. It has been found that the UV-light with high intensity can improve the distribution uniformity of the free radicals induced by UV photons in the solvents, thus improve the density uniformity of the foams. In addition, container wall would influence the concentration distribution of the solution, which affects the density uniformity of the foams. Thus, the UV-light with high intensity was chosen together with polytetrafluoroethylene molds instead of glass molds to prepare the foams with the density non-uniformity less than 10%. β-ray detection technology was used to measure the density uniformity of the TMPTA foams with the density in the range of 10 to 100 mg · cm -3 , and the results show that the lower the foam density is, the worse the density uniformity is. (authors)

  17. Low-Temperature Soft-Cover Deposition of Uniform Large-Scale Perovskite Films for High-Performance Solar Cells.

    Science.gov (United States)

    Ye, Fei; Tang, Wentao; Xie, Fengxian; Yin, Maoshu; He, Jinjin; Wang, Yanbo; Chen, Han; Qiang, Yinghuai; Yang, Xudong; Han, Liyuan

    2017-09-01

    Large-scale high-quality perovskite thin films are crucial to produce high-performance perovskite solar cells. However, for perovskite films fabricated by solvent-rich processes, film uniformity can be prevented by convection during thermal evaporation of the solvent. Here, a scalable low-temperature soft-cover deposition (LT-SCD) method is presented, where the thermal convection-induced defects in perovskite films are eliminated through a strategy of surface tension relaxation. Compact, homogeneous, and convection-induced-defects-free perovskite films are obtained on an area of 12 cm 2 , which enables a power conversion efficiency (PCE) of 15.5% on a solar cell with an area of 5 cm 2 . This is the highest efficiency at this large cell area. A PCE of 15.3% is also obtained on a flexible perovskite solar cell deposited on the polyethylene terephthalate substrate owing to the advantage of presented low-temperature processing. Hence, the present LT-SCD technology provides a new non-spin-coating route to the deposition of large-area uniform perovskite films for both rigid and flexible perovskite devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Distributed large-scale dimensional metrology new insights

    CERN Document Server

    Franceschini, Fiorenzo; Maisano, Domenico

    2011-01-01

    Focuses on the latest insights into and challenges of distributed large scale dimensional metrology Enables practitioners to study distributed large scale dimensional metrology independently Includes specific examples of the development of new system prototypes

  19. LARGE SCALE DISTRIBUTED PARAMETER MODEL OF MAIN MAGNET SYSTEM AND FREQUENCY DECOMPOSITION ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    ZHANG,W.; MARNERIS, I.; SANDBERG, J.

    2007-06-25

    Large accelerator main magnet system consists of hundreds, even thousands, of dipole magnets. They are linked together under selected configurations to provide highly uniform dipole fields when powered. Distributed capacitance, insulation resistance, coil resistance, magnet inductance, and coupling inductance of upper and lower pancakes make each magnet a complex network. When all dipole magnets are chained together in a circle, they become a coupled pair of very high order complex ladder networks. In this study, a network of more than thousand inductive, capacitive or resistive elements are used to model an actual system. The circuit is a large-scale network. Its equivalent polynomial form has several hundred degrees. Analysis of this high order circuit and simulation of the response of any or all components is often computationally infeasible. We present methods to use frequency decomposition approach to effectively simulate and analyze magnet configuration and power supply topologies.

  20. The influence of cathode excavation of cathodic arc evaporator on thickness uniformity and erosion products angle distribution

    Directory of Open Access Journals (Sweden)

    D. V. Duhopel'nikov

    2014-01-01

    Full Text Available Cathodic arc evaporators are used for coating with functional films. Prolonged or buttend evaporators may be used for this purposes. In butt-end evaporator the cathode spots move continuously on the cathode work surface and evaporate cathode material. High depth excavation profile forms on the cathode work surface while the thick coating precipitation (tens or hundreds of microns. The cathode excavation profile is shaped like a “cup” with high walls for electrostatic discharge stabilization systems with axial magnetic fields. Cathode spots move on the bottom of the “cup”. It is very likely that high “cup” walls are formed as a result of lasting work time influence on the uniformity of precipitated films.In the present work the influence of excavation profile walls height on the uniformity of precipitated coating was carried out. The high profile walls are formed due to lasting work of DC vacuum arc evaporator. The cathode material used for tests was 3003 aluminum alloy. The extended substrate was placed parallel to the cathode work surface. Thickness distribution along the substrate length with the new cathode was obtained after 6 hours and after 12 hours of continuous operation.The thickness distribution of precipitated coating showed that the cathode excavation has an influence on the angular distribution of the matter escaping the cathode. It can be clearly seen from the normalized dependence coating thickness vs the distance from the substrate center. Also the angular distribution of the matter flow from the cathode depending on the cathode working time was obtained. It was shown that matter flow from the cathode differs from the LambertKnudsen law. The more the cathode excavation the more this difference.So, cathode excavation profile has an influence on the uniformity of precipitated coating and it is necessary to take in account the cathode excavation profile while coating the thick films.

  1. Effect of non-uniform surface resistance on the quality factor of superconducting niobium cavity

    Science.gov (United States)

    Tan, Weiwei; Lu, Xiangyang; Yang, Ziqin; Zhao, Jifei; Yang, Deyu; Yang, Yujia

    2016-08-01

    The formula Rs = G /Q0 is commonly used in the calculation of the surface resistance of radio frequency niobium superconducting cavities. The applying of such equation is under the assumption that surface resistance is consistent over the cavity. However, the distribution of the magnetic field varies over the cavity. The magnetic field in the equator is much higher than that in the iris. According to Thermal Feedback Theory, it leads non-uniform distribution of the density of heat flux, which results in a different temperature distribution along the cavity inter surface. The BCS surface resistance, which depends largely on the temperature, is different in each local inner surface. In this paper, the effect of surface non-uniform resistance on the quality factor has been studied, through the calculation of Q0 in the original definition of it. The results show that it is necessary to consider the non-uniform distribution of magnetic field when the accelerating field is above 20 MV/m for TESLA cavities. Also, the effect of inhomogeneity of residual resistance on the quality factor is discussed. Its distribution barely affects the quality factor.

  2. Planned studies of charge collection in non-uniformly irradiated Si and GaAs detectors

    International Nuclear Information System (INIS)

    Rosenfeld, A.; Reinhard, M.; Carolan, M.; Kaplan, G.; Lerch, M.; Alexiev, D.

    1995-01-01

    The aim of this project is to study the time and amplitude characteristics of silicon ion-implanted detectors non-uniformly irradiated with fast neutrons in order to predict their radiation behaviour in the LHC and space. It is expected in such detectors increases of the charge deficit due to trapping by large scale traps and transient time increases due to the reduction of the mobility. The theoretical model will be modified to describe the charge kinetics in the electrical field of the detector created by a non uniform space charge distribution. Experimental confirmation techniques are needed to develop non uniform predictable damage of silicon detectors using fast neutron sources (accelerators, reactors) and to study peculiarities of the charge transport in different parts of the detector. In parallel to experimental research will be started the theoretical development of the charge transport model for non-uniform distribution of space charge in the depletion layer (Neff). The model will include the linear distribution of Neff(y) along the detector as well as the change of sign of Neff (conversion from n to p type of silicon) inside the detector

  3. Distributed simulation of large computer systems

    International Nuclear Information System (INIS)

    Marzolla, M.

    2001-01-01

    Sequential simulation of large complex physical systems is often regarded as a computationally expensive task. In order to speed-up complex discrete-event simulations, the paradigm of Parallel and Distributed Discrete Event Simulation (PDES) has been introduced since the late 70s. The authors analyze the applicability of PDES to the modeling and analysis of large computer system; such systems are increasingly common in the area of High Energy and Nuclear Physics, because many modern experiments make use of large 'compute farms'. Some feasibility tests have been performed on a prototype distributed simulator

  4. Evaluation of bacterial nanocellulose-based uniform wound dressing for large area skin transplantation

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Lina [Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); National Engineering Research Center for Nano-Medicine, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhou, Ping [Institute of Organ Transplant of Tongji Hospital, Huazhong University of Science and Technology, Wuhan (China); Zhang, Shengmin [Advanced Biomaterials and Tissue Engineering Center, Huazhong University of Science and Technology, Wuhan (China); Yang, Guang, E-mail: yang_sunny@yahoo.com [Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); National Engineering Research Center for Nano-Medicine, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2013-07-01

    Bacterial nanocellulose (BNC) was biosynthesized by Gluconacetobacter xylinus. The surface area, physicochemical structure and morphology of the materials were characterized. Here provides a method for an efficient production of uniform BNC, which is beneficial for the fast characterization and evaluation of BNC. In vitro cytotoxicity of the materials was evaluated by the proliferation, the adhesion, the viability and the morphology of NIH/3T3 cells. Low cytotoxicity of the BNC was observed, and micrographs demonstrate a good proliferation and adhesion of NIH/3T3 cells on BNC. Large area full-thickness skin defects were made on the back of C57BL/6 mice in animal surgery. The wounds were transplanted with BNC films and the results compared to those in a control group. The rehabilitation of the wound surfaces and the pathological sections of mice were investigated and are discussed. Histological examinations demonstrated faster and better healing effect and lower inflammatory response in the BNC group than those in the control group. Preliminary results on wound dressings from BNC show a curative effect promoting the healing of epithelial tissue. BNC is a promising natural polymer with medical applications in wound dressings. - Highlights: • BNC is expected to be a promising material in wound healing and skin transplantation. • We studied surface area, physicochemical structures and morphology of uniform BNC. • Cyto-evaluation results of BNC-based wound dressing show a good biocompatibility. • Large area skin transplantation experiments suggest a good performance of healing.

  5. Evaluation of bacterial nanocellulose-based uniform wound dressing for large area skin transplantation

    International Nuclear Information System (INIS)

    Fu, Lina; Zhou, Ping; Zhang, Shengmin; Yang, Guang

    2013-01-01

    Bacterial nanocellulose (BNC) was biosynthesized by Gluconacetobacter xylinus. The surface area, physicochemical structure and morphology of the materials were characterized. Here provides a method for an efficient production of uniform BNC, which is beneficial for the fast characterization and evaluation of BNC. In vitro cytotoxicity of the materials was evaluated by the proliferation, the adhesion, the viability and the morphology of NIH/3T3 cells. Low cytotoxicity of the BNC was observed, and micrographs demonstrate a good proliferation and adhesion of NIH/3T3 cells on BNC. Large area full-thickness skin defects were made on the back of C57BL/6 mice in animal surgery. The wounds were transplanted with BNC films and the results compared to those in a control group. The rehabilitation of the wound surfaces and the pathological sections of mice were investigated and are discussed. Histological examinations demonstrated faster and better healing effect and lower inflammatory response in the BNC group than those in the control group. Preliminary results on wound dressings from BNC show a curative effect promoting the healing of epithelial tissue. BNC is a promising natural polymer with medical applications in wound dressings. - Highlights: • BNC is expected to be a promising material in wound healing and skin transplantation. • We studied surface area, physicochemical structures and morphology of uniform BNC. • Cyto-evaluation results of BNC-based wound dressing show a good biocompatibility. • Large area skin transplantation experiments suggest a good performance of healing

  6. Uniform irradiation of irregularly shaped cavities for photodynamic therapy.

    Science.gov (United States)

    Rem, A I; van Gemert, M J; van der Meulen, F W; Gijsbers, G H; Beek, J F

    1997-03-01

    It is difficult to achieve a uniform light distribution in irregularly shaped cavities. We have conducted a study on the use of hollow 'integrating' moulds for more uniform light delivery of photodynamic therapy in irregularly shaped cavities such as the oral cavity. Simple geometries such as a cubical box, a sphere, a cylinder and a 'bottle-neck' geometry have been investigated experimentally and the results have been compared with computed light distributions obtained using the 'radiosity method'. A high reflection coefficient of the mould and the best uniform direct irradiance possible on the inside of the mould were found to be important determinants for achieving a uniform light distribution.

  7. Experimental Investigation of Temperature Distribution along the Length of Uniform Area Fin for Forced and Free Convection

    Science.gov (United States)

    Kannojiya, Vikas; Sharma, Riya; Gaur, Rahul; Jangra, Anil; Yadav, Pushpender; Prajapati, Pooja

    2018-03-01

    The overheating of an industrial component sometimes may leads to system failure. The convection heat transfer from a heated surface can be effectively enhanced by employing fins on that surface. This Paper emphasizes on the experimental investigation of temperature distribution along the length of pin shaped fin. The analysis is performed on a 100 mm long fin made up of brass with 19.6 mm diameter having thermal conductivity as 111 W/m.K. Temperature at different section of the fin along its length is evaluated experimentally and theoretically. The influence of convection mode viz natural & forced convection and variable heat input on the temperature distribution is evaluated. The result outcomes are then compared with the widely accepted analytical relations. A comparison of convective heat transfer coefficient for uniform and non-uniform area fin is also presented. The results by experimental and analytical method are found to be in good agreement for free convection phenomenon.

  8. Out-coupling membrane for large-size organic light-emitting panels with high efficiency and improved uniformity

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Lei, E-mail: dinglei@sust.edu.cn [College of Electrical and Information Engineering, Shaanxi University of Science and Technology, Xi’an, Shaanxi 710021 (China); Wang, Lu-Wei [College of Electrical and Information Engineering, Shaanxi University of Science and Technology, Xi’an, Shaanxi 710021 (China); Zhou, Lei, E-mail: zhzhlei@gmail.com [Faculty of Mathematics and Physics, Huaiyin Institute of Technology, Huai' an 223003 (China); Zhang, Fang-hui [College of Electrical and Information Engineering, Shaanxi University of Science and Technology, Xi’an, Shaanxi 710021 (China)

    2016-12-15

    Highlights: • An out-coupling membrane embedded with a scattering film of SiO{sub 2} spheres and polyethylene terephthalate (PET) plastic was successfully developed for 150 × 150 mm{sup 2} OLEDs. • Remarkable enhancement in efficiency was achieved from the OLEDs with out- coupling membrane. • The uniformity of large-size GOLED lighting panel is remarkably improved. - Abstract: An out-coupling membrane embedded with a scattering film of SiO{sub 2} spheres and polyethylene terephthalate (PET) plastic was successfully developed for 150 × 150 mm{sup 2} green OLEDs. Comparing with a reference OLED panel, an approximately 1-fold enhancement in the forward emission was obtained with an out-coupling membrane adhered to the surface of the external glass substrate of the panel. Moreover, it was verified that the emission color at different viewing angles can be stabilized without apparent spectral distortion. Particularly, the uniformity of the large-area OLEDs was greatly improved. Theoretical calculation clarified that the improved performance of the lighting panels is primarily attributed to the effect of particle scattering.

  9. A poloidal non-uniformity of the collisionless parallel current in a tokamak plasma

    Energy Technology Data Exchange (ETDEWEB)

    Romannikov, A.; Fenzi-Bonizec, C

    2005-07-01

    The collisionless distortion of the ion (electron) distribution function at certain points on a magnetic surface is studied in the framework of a simple model of a large aspect ratio tokamak plasma. The flow velocity driven by this distortion is calculated. The possibility of an additional non-uniform collisionless parallel current density on a magnetic surface, other than the known neo-classical non-uniformity is shown. The difference between the parallel current density on the low and high field side of a magnetic surface is close to the neoclassical bootstrap current density. The first Tore-Supra experimental test indicates the possibility of the poloidal non-uniformity of the parallel current density. (authors)

  10. Estimation of subcriticality and fuel concentration by using 'pattern matching' of neutron flux distribution under non uniformed system

    International Nuclear Information System (INIS)

    Ishitani, Kazuki; Yamane, Yoshihiro

    1999-01-01

    In nuclear fuel reprocessing plants, monitoring the spatial profile of neutron flux to infer subcriticality and distribution of fuel concentration using detectors such as PSPC, is very beneficial in sight of criticality safety. In this paper a method of subcriticality and fuel concentration estimation which is supposed to use under non-uniformed system is proposed. Its basic concept is the pattern matching between measured neutron flux distribution and beforehand calculated one. In any kind of subcriticality estimation, we can regard that measured neutron counts put any kind of black box, and then this black box outputs subcriticality. We proposed the use of artificial neural network or 'pattern matching' as black box which have no theoretical clear base. These method are wholly based on the calculated value as recently advancement of computer code accuracy for criticality safety. The most difference between indirect bias estimation method and our method is that our new approach target are the unknown non-uniform system. (J.P.N.)

  11. Ultrasonic transducer design for uniform insonation

    International Nuclear Information System (INIS)

    Harrison, G.H.; Balcer-Kubiczek, E.K.; McCulloch, D.

    1984-01-01

    Techniques used in transducer development for acoustical imaging have been evaluated for the purpose of producing broad, uniform ultrasonic fields from planar radiators. Such fields should be useful in hyperthermia, physical therapy, and ultrasonic bioeffects studies. Fourier inversion of the circ function yielded a source velocity distribution proportional to (P/r) exp ((-ik/2Z) (2Z/sup 2/+r/sup 2/)) J/sub 1/(krP/Z), where r is the radial source coordinate, k is the wave number, and P is the desired radius of uniform insonation at a depth Z in water. This source distribution can be truncated without significantly degrading the solution. A simpler solution consists of exponentially shading the edge of an otherwise uniformly excited disk transducer. This approach was successfully approximated experimentally

  12. Probability distribution of distance in a uniform ellipsoid: Theory and applications to physics

    International Nuclear Information System (INIS)

    Parry, Michelle; Fischbach, Ephraim

    2000-01-01

    A number of authors have previously found the probability P n (r) that two points uniformly distributed in an n-dimensional sphere are separated by a distance r. This result greatly facilitates the calculation of self-energies of spherically symmetric matter distributions interacting by means of an arbitrary radially symmetric two-body potential. We present here the analogous results for P 2 (r;ε) and P 3 (r;ε) which respectively describe an ellipse and an ellipsoid whose major and minor axes are 2a and 2b. It is shown that for ε=(1-b 2 /a 2 ) 1/2 ≤1, P 2 (r;ε) and P 3 (r;ε) can be obtained as an expansion in powers of ε, and our results are valid through order ε 4 . As an application of these results we calculate the Coulomb energy of an ellipsoidal nucleus, and compare our result to an earlier result quoted in the literature. (c) 2000 American Institute of Physics

  13. Recent ACE 4 Z-pinch experiments: Long implosion time argon loads, uniform fill versus annular shell distributions and the Rayleigh-Taylor instability problem

    International Nuclear Information System (INIS)

    Coleman, P.; Rauch, J.; Rix, W.; Thompson, J.; Wilson, R.

    1997-01-01

    Hammer (1996) and Velikovich (1996) have discussed ways to mitigate the growth of the magneto-Rayleigh-Taylor (MRT) instability in z-pinch (PRS) implosions. They predict that initial mass distributions more complex than a simple annular shell will reduce instability development. Sanford (1996) reported experimental data showing a benefit for a uniform mass distribution compared to a shell; those tests used ''conventional'' load radii of 2.25 and 1.25 cm respectively, and implosion times under 100 ns. However, the instability problem is expected to grow exponentially as the implosion time, or alternatively the initial radius, increases. Thus we made a comparison of a uniform fill load with a shell but at larger radii, 3.6 and 2.5 cm respectively, and at implosion times well above 100 ns. We see nearly a factor of 10X improvement in peak K-shell power and 2X increase in K-shell yield for the uniform mass load. Hence it appears that suitable tailoring of the imploding mass distribution can significantly limit the instability growth

  14. School Uniform Policies in Public Schools

    Science.gov (United States)

    Brunsma, David L.

    2006-01-01

    The movement for school uniforms in public schools continues to grow despite the author's research indicating little if any impact on student behavior, achievement, and self-esteem. The author examines the distribution of uniform policies by region and demographics, the impact of these policies on perceptions of school climate and safety, and…

  15. Internal electric-field-lines distribution in CdZnTe detectors measured using X-ray mapping

    International Nuclear Information System (INIS)

    Bolotnikov, A.E.; Camarda, G.S.; Cui, Y.; Hossain, A.; Yang, G.; Yao, H.W.; James, R.B.

    2009-01-01

    The ideal operation of CdZnTe devices entails having a uniformly distributed internal electric field. Such uniformity especially is critical for thick long-drift-length detectors, such as large-volume CPG and 3-D multi-pixel devices. Using a high-spatial resolution X-ray mapping technique, we investigated the distribution of the electric field in real devices. Our measurements demonstrate that in thin detectors, 1 cm, with a large aspect ratio (thickness-to-width ratio), we observed two effects: the electric field lines bending away from or towards the side surfaces, which we called, respectively, the focusing field-line distribution and the defocusing field-line distribution. In addition to these large-scale variations, the field-line distributions were locally perturbed by the presence of extended defects and residual strains existing inside the crystals. We present our data clearly demonstrating the non-uniformity of the internal electric field

  16. UMAPRM: Uniformly sampling the medial axis

    KAUST Repository

    Yeh, Hsin-Yi Cindy

    2014-05-01

    © 2014 IEEE. Maintaining clearance, or distance from obstacles, is a vital component of successful motion planning algorithms. Maintaining high clearance often creates safer paths for robots. Contemporary sampling-based planning algorithms That utilize The medial axis, or The set of all points equidistant To Two or more obstacles, produce higher clearance paths. However, They are biased heavily Toward certain portions of The medial axis, sometimes ignoring parts critical To planning, e.g., specific Types of narrow passages. We introduce Uniform Medial Axis Probabilistic RoadMap (UMAPRM), a novel planning variant That generates samples uniformly on The medial axis of The free portion of Cspace. We Theoretically analyze The distribution generated by UMAPRM and show its uniformity. Our results show That UMAPRM\\'s distribution of samples along The medial axis is not only uniform but also preferable To other medial axis samplers in certain planning problems. We demonstrate That UMAPRM has negligible computational overhead over other sampling Techniques and can solve problems The others could not, e.g., a bug Trap. Finally, we demonstrate UMAPRM successfully generates higher clearance paths in The examples.

  17. Rod-coating: towards large-area fabrication of uniform reduced graphene oxide films for flexible touch screens.

    Science.gov (United States)

    Wang, Jie; Liang, Minghui; Fang, Yan; Qiu, Tengfei; Zhang, Jin; Zhi, Linjie

    2012-06-05

    A novel strategy is developed for the large-scale fabrication of reduced graphene oxide films directly on flexible substrates in a controlled manner by the combination of a rod-coating technique and room-temperature reduction of graphene oxide. The as-prepared films display excellent uniformity, good transparency and conductivity, and great flexibility in a touch screen. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Testing the Pareto against the lognormal distributions with the uniformly most powerful unbiased test applied to the distribution of cities.

    Science.gov (United States)

    Malevergne, Yannick; Pisarenko, Vladilen; Sornette, Didier

    2011-03-01

    Fat-tail distributions of sizes abound in natural, physical, economic, and social systems. The lognormal and the power laws have historically competed for recognition with sometimes closely related generating processes and hard-to-distinguish tail properties. This state-of-affair is illustrated with the debate between Eeckhout [Amer. Econ. Rev. 94, 1429 (2004)] and Levy [Amer. Econ. Rev. 99, 1672 (2009)] on the validity of Zipf's law for US city sizes. By using a uniformly most powerful unbiased (UMPU) test between the lognormal and the power-laws, we show that conclusive results can be achieved to end this debate. We advocate the UMPU test as a systematic tool to address similar controversies in the literature of many disciplines involving power laws, scaling, "fat" or "heavy" tails. In order to demonstrate that our procedure works for data sets other than the US city size distribution, we also briefly present the results obtained for the power-law tail of the distribution of personal identity (ID) losses, which constitute one of the major emergent risks at the interface between cyberspace and reality.

  19. Effect of Pressure on the Uniformity of Nozzles Transverse Distribution and Mathematical Model Development

    Directory of Open Access Journals (Sweden)

    Vladimir Višacki

    2017-01-01

    Full Text Available Timely and high-quality application of pesticides contributes to environmental protection, economical production and production of healthy food. The efficacy of pesticide application depends not only on the quality of pesticides but also the quality of the application. One of the factor that most influences the quality of applications, from the standpoint of mechanization, are nozzles. They working liquid applied on the surface the plant resulting in the same volume of pesticide is applied to the entire surface of the plants. To achieve this goal, nozzles must be performed uniform application of working liquid per unit area, or tractor sprayer working width. The variable factor in the application of pesticides may be nozzle and operating pressure. With increasing working pressure obtained smaller droplets. The paper presents test of three different nozzles. Each nozzle is characterized by a flat jet with an angle of 110° and a flow rate of 1.6 l∙min−1 at a pressure of 3 bar. Differ from each other are by the way of disintegration of the jet. Exactly this characteristic causes that with pressure change coming to changes in the uniformity of nozzles transverse distribution. So the best distribution has nozzle with a flat jet. The coefficient of variation is between roughly from 4 to 6 % at the pressure application of 2 to 4 bar. Obtained mathematical model that describes changes in the coefficient of variation depending on pressure applications can be a good basis for easy harmonization parameters in the pesticide application.

  20. Impact of Uniform Methods on Interlaboratory Antibody Titration Variability: Antibody Titration and Uniform Methods.

    Science.gov (United States)

    Bachegowda, Lohith S; Cheng, Yan H; Long, Thomas; Shaz, Beth H

    2017-01-01

    -Substantial variability between different antibody titration methods prompted development and introduction of uniform methods in 2008. -To determine whether uniform methods consistently decrease interlaboratory variation in proficiency testing. -Proficiency testing data for antibody titration between 2009 and 2013 were obtained from the College of American Pathologists. Each laboratory was supplied plasma and red cells to determine anti-A and anti-D antibody titers by their standard method: gel or tube by uniform or other methods at different testing phases (immediate spin and/or room temperature [anti-A], and/or anti-human globulin [AHG: anti-A and anti-D]) with different additives. Interlaboratory variations were compared by analyzing the distribution of titer results by method and phase. -A median of 574 and 1100 responses were reported for anti-A and anti-D antibody titers, respectively, during a 5-year period. The 3 most frequent (median) methods performed for anti-A antibody were uniform tube room temperature (147.5; range, 119-159), uniform tube AHG (143.5; range, 134-150), and other tube AHG (97; range, 82-116); for anti-D antibody, the methods were other tube (451; range, 431-465), uniform tube (404; range, 382-462), and uniform gel (137; range, 121-153). Of the larger reported methods, uniform gel AHG phase for anti-A and anti-D antibodies had the most participants with the same result (mode). For anti-A antibody, 0 of 8 (uniform versus other tube room temperature) and 1 of 8 (uniform versus other tube AHG), and for anti-D antibody, 0 of 8 (uniform versus other tube) and 0 of 8 (uniform versus other gel) proficiency tests showed significant titer variability reduction. -Uniform methods harmonize laboratory techniques but rarely reduce interlaboratory titer variance in comparison with other methods.

  1. Probabilistic uniformities of uniform spaces

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Lopez, J.; Romaguera, S.; Sanchis, M.

    2017-07-01

    The theory of metric spaces in the fuzzy context has shown to be an interesting area of study not only from a theoretical point of view but also for its applications. Nevertheless, it is usual to consider these spaces as classical topological or uniform spaces and there are not too many results about constructing fuzzy topological structures starting from a fuzzy metric. Maybe, H/{sup o}hle was the first to show how to construct a probabilistic uniformity and a Lowen uniformity from a probabilistic pseudometric /cite{Hohle78,Hohle82a}. His method can be directly translated to the context of fuzzy metrics and allows to characterize the categories of probabilistic uniform spaces or Lowen uniform spaces by means of certain families of fuzzy pseudometrics /cite{RL}. On the other hand, other different fuzzy uniformities can be constructed in a fuzzy metric space: a Hutton $[0,1]$-quasi-uniformity /cite{GGPV06}; a fuzzifiying uniformity /cite{YueShi10}, etc. The paper /cite{GGRLRo} gives a study of several methods of endowing a fuzzy pseudometric space with a probabilistic uniformity and a Hutton $[0,1]$-quasi-uniformity. In 2010, J. Guti/'errez Garc/'{/i}a, S. Romaguera and M. Sanchis /cite{GGRoSanchis10} proved that the category of uniform spaces is isomorphic to a category formed by sets endowed with a fuzzy uniform structure, i. e. a family of fuzzy pseudometrics satisfying certain conditions. We will show here that, by means of this isomorphism, we can obtain several methods to endow a uniform space with a probabilistic uniformity. Furthermore, these constructions allow to obtain a factorization of some functors introduced in /cite{GGRoSanchis10}. (Author)

  2. Even distribution/dividing of single-phase fluids by symmetric bifurcation of flow channels

    International Nuclear Information System (INIS)

    Liu, Hong; Li, Peiwen

    2013-01-01

    Highlights: ► We addressed an issue of distributing a flow to a number of flow channels uniformly. ► The flow distribution is accomplished through bifurcation of channels. ► Some key parameters to the flow distribution uniformity have been identified. ► Flow uniformity was studied for several versions of flow distributor designs. ► A novel fluid packaging device of high efficiency was provided. -- Abstract: This study addresses a fundamental issue of distributing a single-phase fluid flow into a number of flow channels uniformly. A basic mechanism of flow distribution is accomplished through bifurcation of channels that symmetrically split one flow channel into two downstream channels. Applying the basic mechanism, cascades flow distributions are designed to split one flow into a large number of downstream flows uniformly. Some key parameters decisive to the flow distribution uniformity in such a system have been identified, and the flow distribution uniformity of air was studied for several versions of flow distributor designs using CFD analysis. The effect of the key parameters of the flow channel designs to the flow distribution uniformity was investigated. As an example of industrial application, a novel fluid packaging device of high efficiency was proposed and some CFD analysis results for the device were provided. The optimized flow distributor makes a very good uniform flow distribution which will significantly improve the efficiency of fluid packaging. The technology is expected to be of great significance to many industrial devices that require high uniformity of flow distribution

  3. Prediction of the Velocity Contours in Triangular Channel with Non-uniform Roughness Distributions by Adaptive Neuro-Fuzzy Inference System

    Directory of Open Access Journals (Sweden)

    Sara Bardestani

    2017-09-01

    Full Text Available Triangular channels have different applications in many water and wastewater engineering problems. For this purpose investigating hydraulic characteristics of flow in these sections has great importance. Researchers have presented different prediction methods for the velocity contours in prismatic sections. Most proposed methods are not able to consider the effect of walls roughness, the roughness distribution and secondary flows. However, due to complexity and nonlinearity of velocity contours in open channel flow, there is no simple relationship that can be fully able to exactly draw the velocity contours. In this paper an efficient approach for modeling velocity contours in triangular open channels with non-uniform roughness distributions by Adaptive Neuro-Fuzzy Inference System (ANFIS has been suggested. For training and testing model, the experimental data including 1703 data in triangular channels with geometric symmetry and non-uniform roughness distributions have been used. Comparing experimental results with predicted values by model indicates that ANFIS model is capable to be used in simulation of local velocity and determining velocity contours and the independent evaluation showed that the calculated values of discharge and depth-averaged velocity from model information are precisely in conformity with experimental values.

  4. A method for generating skewed random numbers using two overlapping uniform distributions

    International Nuclear Information System (INIS)

    Ermak, D.L.; Nasstrom, J.S.

    1995-02-01

    The objective of this work was to implement and evaluate a method for generating skewed random numbers using a combination of uniform random numbers. The method provides a simple and accurate way of generating skewed random numbers from the specified first three moments without an a priori specification of the probability density function. We describe the procedure for generating skewed random numbers from unifon-n random numbers, and show that it accurately produces random numbers with the desired first three moments over a range of skewness values. We also show that in the limit of zero skewness, the distribution of random numbers is an accurate approximation to the Gaussian probability density function. Future work win use this method to provide skewed random numbers for a Langevin equation model for diffusion in skewed turbulence

  5. Experimental study of the heat transfers and passive cooling potential of a ventilated plenum designed for uniform air distribution

    DEFF Research Database (Denmark)

    Hviid, Christian Anker; Lessing, Julian

    2016-01-01

    suspended ceiling to uniformly distribute the supply air to the occupied zone. This, in effect, increases the thermal mass of the room because the upper slab of the room no longer is isolated from the occupied zone. In this study, the cooling potential of a diffuse ceiling ventilation system is i...

  6. Simulation optimization of filament parameters for uniform depositions of diamond films on surfaces of ultra-large circular holes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xinchang, E-mail: wangxinchangz@163.com; Shen, Xiaotian; Sun, Fanghong; Shen, Bin

    2016-12-01

    Highlights: • A verified simulation model using a novel filament arrangement is constructed. • Influences of filament parameters are clarified. • A coefficient between simulated and experimental results is proposed. • Orthogonal simulations are adopted to optimize filament parameters. • A general filament arrangement suitable for different conditions is determined. - Abstract: Chemical vapor deposition (CVD) diamond films have been widely applied as protective coatings on varieties of anti-frictional and wear-resistant components, owing to their excellent mechanical and tribological properties close to the natural diamond. In applications of some components, the inner hole surface will serve as the working surface that suffers severe frictional or erosive wear. It is difficult to realize uniform depositions of diamond films on surfaces of inner holes, especially ultra-large inner holes. Adopting a SiC compact die with an aperture of 80 mm as an example, a novel filament arrangement with a certain number of filaments evenly distributed on a circle is designed, and specific effects of filament parameters, including the filament number, arrangement direction, filament temperature, filament diameter, circumradius and the downward translation, on the substrate temperature distribution are studied by computational fluid dynamics (CFD) simulations based on the finite volume method (FVM), adopting a modified computational model well consistent with the actual deposition environment. Corresponding temperature measurement experiments are also conducted to verify the rationality of the computational model. From the aspect of depositing uniform boron-doped micro-crystalline, undoped micro-crystalline and undoped fine-grained composite diamond (BDM-UMC-UFGCD) film on such the inner hole surface, filament parameters as mentioned above are accurately optimized and compensated by orthogonal simulations. Moreover, deposition experiments adopting compensated optimized

  7. Non-uniform velocity profile mechanism for flame stabilization in a porous radiant burner

    Energy Technology Data Exchange (ETDEWEB)

    Catapan, R.C.; Costa, M. [Mechanical Engineering Department, Instituto Superior Tecnico, Technical University of Lisbon, Avenida Rovisco Pais, 1049-001 Lisbon (Portugal); Oliveira, A.A.M. [Mechanical Engineering Department, Federal University of Santa Catarina, Campus Universitario Professor Joao David Ferreira Lima, 88040-900 Florianopolis, SC (Brazil)

    2011-01-15

    Industrial processes where the heating of large surfaces is required lead to the possibility of using large surface porous radiant burners. This causes additional temperature uniformity problems, since it is increasingly difficult to evenly distribute the reactant mixture over a large burner surface while retaining its stability and keeping low pollutant emissions. In order to allow for larger surface area burners, a non-uniform velocity profile mechanism for flame stabilization in a porous radiant burner using a single large injection hole is proposed and analyzed for a double-layered burner operating in open and closed hot (laboratory-scale furnace, with temperature-controlled, isothermal walls) environments. In both environments, local mean temperatures within the porous medium have been measured. For lower reactant flow rate and ambient temperature the flame shape is conical and anchored at the rim of the injection hole. As the volumetric flow rate or furnace temperature is raised, the flame undergoes a transition to a plane flame stabilized near the external burner surface. However, the stability range envelope remains the same in both regimes. (author)

  8. Ideal flood field images for SPECT uniformity correction

    International Nuclear Information System (INIS)

    Oppenheim, B.E.; Appledorn, C.R.

    1984-01-01

    Since as little as 2.5% camera non-uniformity can cause disturbing artifacts in SPECT imaging, the ideal flood field images for uniformity correction would be made with the collimator in place using a perfectly uniform sheet source. While such a source is not realizable the equivalent images can be generated by mapping the activity distribution of a Co-57 sheet source and correcting subsequent images of the source with this mapping. Mapping is accomplished by analyzing equal-time images of the source made in multiple precisely determined positions. The ratio of counts detected in the same region of two images is a measure of the ratio of the activities of the two portions of the source imaged in that region. The activity distribution in the sheet source is determined from a set of such ratios. The more source positions imaged in a given time, the more accurate the source mapping, according to results of a computer simulation. A 1.9 mCi Co-57 sheet source was shifted by 12 mm increments along the horizontal and vertical axis of the camera face to 9 positions on each axis. The source was imaged for 20 min in each position and 214 million total counts were accumulated. The activity distribution of the source, relative to the center pixel, was determined for a 31 x 31 array. The integral uniformity was found to be 2.8%. The RMS error for such a mapping was determined by computer simulation to be 0.46%. The activity distribution was used to correct a high count flood field image for non-uniformities attributable to the Co-57 source. Such a corrected image represents camera plus collimator response to an almost perfectly uniform sheet source

  9. Large-area uniform periodic microstructures on fused silica induced by surface phonon polaritons and incident laser

    Science.gov (United States)

    Zhang, Chuanchao; Liao, Wei; Zhang, Lijuan; Jiang, Xiaolong; Chen, Jing; Wang, Haijun; Luan, Xiaoyu; Yuan, Xiaodong

    2018-06-01

    A simple and convenient means to self-organize large-area uniform periodic microstructures on fused silica by using multiple raster scans of microsecond CO2 laser pulses with beam spot overlapping at normal incidence is presented, which is based on laser-induced periodic surface structures (LIPSS) attributed to the interference between surface phonon polaritons and incident CO2 laser. The evolution of fused silica surface morphologies with increasing raster scans indicates that the period of microstructures changed from 10.6 μm to 9 μm and the profiles of microstructures changed from a sinusoidal curve to a half-sinusoidal shape. Numerical simulation results suggest that the formation of the half-sinusoidal profile is due to the exponential relationship between evaporation rate and surface temperature inducing by the intensive interference between surface phonon polaritons and incident laser. The fabricated uniform periodic microstructures show excellent structural color effect in both forward-diffraction and back-diffraction.

  10. Development of a spatially uniform fast ionization wave in a large-volume discharge

    International Nuclear Information System (INIS)

    Zatsepin, D.V.; Starikovskaya, S.M.; Starikovskii, A.Yu.

    1998-01-01

    A study is made of a high-voltage nanosecond breakdown in the form of a fast ionization wave produced in a large-volume (401) discharge chamber. The propagation speed of the wave front and the integral energy deposition in a plasma are measured for various regimes of the air discharge at pressures of 10 -2 -4 Torr. A high degree of both the spatial uniformity of the discharge and the reproducibility of the discharge parameters is obtained. The possibility of the development of a fast ionization wave in an electrodeless system is demonstrated. A transition of the breakdown occurring in the form of a fast ionization wave into the streamer breakdown is observed. It is shown that such discharges are promising for technological applications

  11. Uniformly Distributed Graphene Domain Grows on Standing Copper via Low-Pressure Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Shih-Hao Chan

    2013-01-01

    Full Text Available Uniformly distributed graphene domains were synthesized on standing copper foil by a low-pressure chemical vapor deposition system. This method improved the distribution of the graphene domains at different positions on the same piece of copper foil along the forward direction of the gas flow. Scanning electron microscopy (SEM showed the average size of the graphene domains to be about ~20 m. This results show that the sheet resistance of monolayer graphene on a polyethylene terephthalate (PET substrate is about ~359 /□ whereas that of the four-layer graphene films is about ~178 /□, with a transmittance value of 88.86% at the 550 nm wavelength. Furthermore, the sheet resistance can be reduced with the addition of HNO3 resulting in a value of 84 /□. These values meet the absolute standard for touch sensor applications, so we believe that this method can be a candidate for some transparent conductive electrode applications.

  12. Thermally Dried Ink-Jet Process for 6,13-Bis(triisopropylsilylethynyl)-Pentacene for High Mobility and High Uniformity on a Large Area Substrate

    Science.gov (United States)

    Ryu, Gi Seong; Lee, Myung Won; Jeong, Seung Hyeon; Song, Chung Kun

    2012-05-01

    In this study we developed a simple ink-jet process for 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene), which is known as a high-mobility soluble organic semiconductor, to achieve relatively high-mobility and high-uniformity performance for large-area applications. We analyzed the behavior of fluorescent particles in droplets and applied the results to determining a method of controlling the behavior of TIPS-pentacene molecules. The grain morphology of TIPS-pentacene varied depending on the temperature applied to the droplets during drying. We were able to obtain large and uniform grains at 46 °C without any “coffee stain”. The process was applied to a large-size organic thin-film transistor (OTFT) backplane for an electrophoretic display panel containing 192×150 pixels on a 6-in.-sized substrate. The average of mobilities of 36 OTFTs, which were taken from different locations of the backplane, was 0.44±0.08 cm2·V-1·s-1, with a small deviation of 20%, over a 6-in.-size area comprising 28,800 OTFTs. This process providing high mobility and high uniformity can be achieved by simply maintaining the whole area of the substrate at a specific temperature (46 °C in this case) during drying of the droplets.

  13. Thermally dried ink-jet process for 6,13-bis(triisopropylsilylethynyl)-pentacene for high mobility and high uniformity on a large area substrate

    Science.gov (United States)

    Ryu, Gi Seong; Lee, Myung Won; Jeong, Seung Hyeon; Song, Chung Kun

    2012-01-01

    In this study we developed a simple ink-jet process for 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene), which is known as a high-mobility soluble organic semiconductor, to achieve relatively high-mobility and high-uniformity performance for large-area applications. We analyzed the behavior of fluorescent particles in droplets and applied the results to determining a method of controlling the behavior of TIPS-pentacene molecules. The grain morphology of TIPS-pentacene varied depending on the temperature applied to the droplets during drying. We were able to obtain large and uniform grains at 46 degrees C without any "coffee stain". The process was applied to a large-size organic thin-film transistor (OTFT) backplane for an electrophoretic display panel containing 192 x 150 pixels on a 6-in.-sized substrate. The average of mobilities of 36 OTFTs, which were taken from different locations of the backplane, was 0.44 +/- 0.08 cm2.V-1.s-1, with a small deviation of 20%, over a 6-in.-size area comprising 28,800 OTFTs. This process providing high mobility and high uniformity can be achieved by simply maintaining the whole area of the substrate at a specific temperature (46 degrees C in this case) during drying of the droplets.

  14. Electron Beam Dose Distribution in the Presence of Non-Uniform Magnetic Field

    Directory of Open Access Journals (Sweden)

    Mohamad Javad Tahmasebi-Birgani

    2014-04-01

    Full Text Available Introduction Magnetic fields are capable of altering the trajectory of electron beams andcan be used in radiation therapy.Theaim of this study was to produce regions with dose enhancement and reduction in the medium. Materials and Methods The NdFeB permanent magnets were arranged on the electron applicator in several configurations. Then, after the passage of the electron beams (9 and 15 MeV Varian 2100C/D through the non-uniform magnetic field, the Percentage Depth Dose(PDDs on central axis and dose profiles in three depths for each energy were measured in a 3D water phantom. Results For all magnet arrangements and for two different energies, the surface dose increment and shift in depth of maximum dose (dmax were observed. In addition, the pattern of dose distribution in buildup region was changed. Measurement of dose profile showed dose localization and spreading in some other regions. Conclusion The results of this study confirms that using magnetic field can alter the dose deposition patterns and as a result can produce dose enhancement as well as dose reduction in the medium using high-energy electron beams. These effects provide dose distribution with arbitrary shapes for use in radiation therapy.

  15. The ciliate Paramecium shows higher motility in non-uniform chemical landscapes.

    Directory of Open Access Journals (Sweden)

    Carl Giuffre

    Full Text Available We study the motility behavior of the unicellular protozoan Paramecium tetraurelia in a microfluidic device that can be prepared with a landscape of attracting or repelling chemicals. We investigate the spatial distribution of the positions of the individuals at different time points with methods from spatial statistics and Poisson random point fields. This makes quantitative the informal notion of "uniform distribution" (or lack thereof. Our device is characterized by the absence of large systematic biases due to gravitation and fluid flow. It has the potential to be applied to the study of other aquatic chemosensitive organisms as well. This may result in better diagnostic devices for environmental pollutants.

  16. Design and testing of a uniformly solar energy TIR-R concentration lenses for HCPV systems.

    Science.gov (United States)

    Shen, S C; Chang, S J; Yeh, C Y; Teng, P C

    2013-11-04

    In this paper, total internal reflection-refraction (TIR-R) concentration (U-TIR-R-C) lens module were designed for uniformity using the energy configuration method to eliminate hot spots on the surface of solar cell and increase conversion efficiency. The design of most current solar concentrators emphasizes the high-power concentration of solar energy, however neglects the conversion inefficiency resulting from hot spots generated by uneven distributions of solar energy concentrated on solar cells. The energy configuration method proposed in this study employs the concept of ray tracing to uniformly distribute solar energy to solar cells through a U-TIR-R-C lens module. The U-TIR-R-C lens module adopted in this study possessed a 76-mm diameter, a 41-mm thickness, concentration ratio of 1134 Suns, 82.6% optical efficiency, and 94.7% uniformity. The experiments demonstrated that the U-TIR-R-C lens module reduced the core temperature of the solar cell from 108 °C to 69 °C and the overall temperature difference from 45 °C to 10 °C, and effectively relative increased the conversion efficiency by approximately 3.8%. Therefore, the U-TIR-R-C lens module designed can effectively concentrate a large area of sunlight onto a small solar cell, and the concentrated solar energy can be evenly distributed in the solar cell to achieve uniform irradiance and effectively eliminate hot spots.

  17. Mechanical Effects of the Non-Uniform Current Distribution on HTS Coils for Accelerators Wound with REBCO Roebel Cable

    CERN Document Server

    Murtomaeki, Jaako; Kirby, Glen; Rossi, Lucio; Ruuskanen, Janne; Stenvall, Antti; Murtomaeki, Jaako

    2017-01-01

    Future high-energy accelerators will need very high magnetic fields in the range of 20 T. The EuCARD-2 WP10 Future Magnets collaboration is aiming at testing HTS-based Roebel cables in an accelerator magnet. The demonstrator should produce around 17 T, when inserted into the 100 mm aperture of Feather-M2 13 T outsert magnet. HTS Roebel cables are assembled from meander shaped REBCO coated conductor tapes. In comparison with fair level of uniformity of current distribution in cables made out of round Nb-Ti or Nb$_{3}$Sn strands, current distribution within the coils wound from Roebel cables is highly non-homogeneous. It results in nonuniform electromagnetic force distribution over the cable that could damage the very thin REBCO superconducting layer. This paper focuses on the numerical models to describe the effect of the non-homogenous current distribution on stress distribution in the demonstrator magnet designed for the EuCARD-2 project. Preliminary results indicate that the impregnation bonding betweenthe...

  18. A uniform approach for programming distributed heterogeneous computing systems.

    Science.gov (United States)

    Grasso, Ivan; Pellegrini, Simone; Cosenza, Biagio; Fahringer, Thomas

    2014-12-01

    Large-scale compute clusters of heterogeneous nodes equipped with multi-core CPUs and GPUs are getting increasingly popular in the scientific community. However, such systems require a combination of different programming paradigms making application development very challenging. In this article we introduce libWater, a library-based extension of the OpenCL programming model that simplifies the development of heterogeneous distributed applications. libWater consists of a simple interface, which is a transparent abstraction of the underlying distributed architecture, offering advanced features such as inter-context and inter-node device synchronization. It provides a runtime system which tracks dependency information enforced by event synchronization to dynamically build a DAG of commands, on which we automatically apply two optimizations: collective communication pattern detection and device-host-device copy removal. We assess libWater's performance in three compute clusters available from the Vienna Scientific Cluster, the Barcelona Supercomputing Center and the University of Innsbruck, demonstrating improved performance and scaling with different test applications and configurations.

  19. Natural ventilation in an enclosure induced by a heat source distributed uniformly over a vertical wall

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z.D.; Li, Y.; Mahoney, J. [CSIRO Building, Construction and Engineering, Advanced Thermo-Fluids Technologies Lab., Highett, VIC (Australia)

    2001-05-01

    A simple multi-layer stratification model is suggested for displacement ventilation in a single-zone building driven by a heat source distributed uniformly over a vertical wall. Theoretical expressions are obtained for the stratification interface height and ventilation flow rate and compared with those obtained by an existing model available in the literature. Experiments were also carried out using a recently developed fine-bubble modelling technique. It was shown that the experimental results obtained using the fine-bubble technique are in good agreement with the theoretical predictions. (Author)

  20. Isodose distributions and dose uniformity in the Portuguese gamma irradiation facility calculated using the MCNP code

    CERN Document Server

    Oliveira, C

    2001-01-01

    A systematic study of isodose distributions and dose uniformity in sample carriers of the Portuguese Gamma Irradiation Facility was carried out using the MCNP code. The absorbed dose rate, gamma flux per energy interval and average gamma energy were calculated. For comparison purposes, boxes filled with air and 'dummy' boxes loaded with layers of folded and crumpled newspapers to achieve a given value of density were used. The magnitude of various contributions to the total photon spectra, including source-dependent factors, irradiator structures, sample material and other origins were also calculated.

  1. Uniform approximation is more appropriate for Wilcoxon Rank-Sum Test in gene set analysis.

    Directory of Open Access Journals (Sweden)

    Zhide Fang

    Full Text Available Gene set analysis is widely used to facilitate biological interpretations in the analyses of differential expression from high throughput profiling data. Wilcoxon Rank-Sum (WRS test is one of the commonly used methods in gene set enrichment analysis. It compares the ranks of genes in a gene set against those of genes outside the gene set. This method is easy to implement and it eliminates the dichotomization of genes into significant and non-significant in a competitive hypothesis testing. Due to the large number of genes being examined, it is impractical to calculate the exact null distribution for the WRS test. Therefore, the normal distribution is commonly used as an approximation. However, as we demonstrate in this paper, the normal approximation is problematic when a gene set with relative small number of genes is tested against the large number of genes in the complementary set. In this situation, a uniform approximation is substantially more powerful, more accurate, and less intensive in computation. We demonstrate the advantage of the uniform approximations in Gene Ontology (GO term analysis using simulations and real data sets.

  2. Effects of combustible stacking in large compartments

    DEFF Research Database (Denmark)

    Gentili, Filippo; Giuliani, Luisa; Bontempi, Franco

    2013-01-01

    This paper focuses on the modelling of fire in case of various distributions of combustible materials in a large compartment. Large compartments often represent a challenge for structural fire safety, because of lack of prescriptive rules to follow and difficulties of taking into account the effect...... of non uniform distribution of the combustible materials and fire propagation. These aspects are discussed in this paper with reference to an industrial steel building, taken as case study. Fires triggered by the burning of wooden pallets stored in the premises have been investigated with respect...

  3. Beam uniformity of flat top lasers

    Science.gov (United States)

    Chang, Chao; Cramer, Larry; Danielson, Don; Norby, James

    2015-03-01

    Many beams that output from standard commercial lasers are multi-mode, with each mode having a different shape and width. They show an overall non-homogeneous energy distribution across the spot size. There may be satellite structures, halos and other deviations from beam uniformity. However, many scientific, industrial and medical applications require flat top spatial energy distribution, high uniformity in the plateau region, and complete absence of hot spots. Reliable standard methods for the evaluation of beam quality are of great importance. Standard methods are required for correct characterization of the laser for its intended application and for tight quality control in laser manufacturing. The International Organization for Standardization (ISO) has published standard procedures and definitions for this purpose. These procedures have not been widely adopted by commercial laser manufacturers. This is due to the fact that they are unreliable because an unrepresentative single-pixel value can seriously distort the result. We hereby propose a metric of beam uniformity, a way of beam profile visualization, procedures to automatically detect hot spots and beam structures, and application examples in our high energy laser production.

  4. Adding muscle where you need it: non-uniform hypertrophy patterns in elite sprinters.

    Science.gov (United States)

    Handsfield, G G; Knaus, K R; Fiorentino, N M; Meyer, C H; Hart, J M; Blemker, S S

    2017-10-01

    Sprint runners achieve much higher gait velocities and accelerations than average humans, due in part to large forces generated by their lower limb muscles. Various factors have been explored in the past to understand sprint biomechanics, but the distribution of muscle volumes in the lower limb has not been investigated in elite sprinters. In this study, we used non-Cartesian MRI to determine muscle sizes in vivo in a group of 15 NCAA Division I sprinters. Normalizing muscle sizes by body size, we compared sprinter muscles to non-sprinter muscles, calculated Z-scores to determine non-uniformly large muscles in sprinters, assessed bilateral symmetry, and assessed gender differences in sprinters' muscles. While limb musculature per height-mass was 22% greater in sprinters than in non-sprinters, individual muscles were not all uniformly larger. Hip- and knee-crossing muscles were significantly larger among sprinters (mean difference: 30%, range: 19-54%) but only one ankle-crossing muscle was significantly larger (tibialis posterior, 28%). Population-wide asymmetry was not significant in the sprint population but individual muscle asymmetries exceeded 15%. Gender differences in normalized muscle sizes were not significant. The results of this study suggest that non-uniform hypertrophy patterns, particularly large hip and knee flexors and extensors, are advantageous for fast sprinting. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. Achieving Uniform Carriers Distribution in MBE Grown Compositionally Graded InGaN Multiple-Quantum-Well LEDs

    KAUST Repository

    Mishra, Pawan; Janjua, Bilal; Ng, Tien Khee; Shen, Chao; Salhi, Abdelmajid; Alyamani, Ahmed; El-Desouki, Munir; Ooi, Boon S.

    2015-01-01

    We investigated the design and growth of compositionally-graded InGaN multiple quantum wells (MQW) based light-emitting diode (LED) without an electron-blocking layer (EBL). Numerical investigation showed uniform carrier distribution in the active region, and higher radiative recombination rate for the optimized graded-MQW design, i.e. In0→xGa1→(1-x)N / InxGa(1-x)N / Inx→0Ga(1-x)→1N, as compared to the conventional stepped-MQW-LED. The composition-grading schemes, such as linear, parabolic, and Fermi-function profiles were numerically investigated for comparison. The stepped- and graded-MQW-LED were then grown using plasma assisted molecular beam epitaxy (PAMBE) through surface-stoichiometry optimization based on reflection high-energy electron-diffraction (RHEED) in-situ observations. Stepped- and graded-MQW-LED showed efficiency roll over at 160 A/cm2 and 275 A/cm2, respectively. The extended threshold current density roll-over (droop) in graded-MQW-LED is due to the improvement in carrier uniformity and radiative recombination rate, consistent with the numerical simulation.

  6. Achieving Uniform Carriers Distribution in MBE Grown Compositionally Graded InGaN Multiple-Quantum-Well LEDs

    KAUST Repository

    Mishra, Pawan

    2015-05-06

    We investigated the design and growth of compositionally-graded InGaN multiple quantum wells (MQW) based light-emitting diode (LED) without an electron-blocking layer (EBL). Numerical investigation showed uniform carrier distribution in the active region, and higher radiative recombination rate for the optimized graded-MQW design, i.e. In0→xGa1→(1-x)N / InxGa(1-x)N / Inx→0Ga(1-x)→1N, as compared to the conventional stepped-MQW-LED. The composition-grading schemes, such as linear, parabolic, and Fermi-function profiles were numerically investigated for comparison. The stepped- and graded-MQW-LED were then grown using plasma assisted molecular beam epitaxy (PAMBE) through surface-stoichiometry optimization based on reflection high-energy electron-diffraction (RHEED) in-situ observations. Stepped- and graded-MQW-LED showed efficiency roll over at 160 A/cm2 and 275 A/cm2, respectively. The extended threshold current density roll-over (droop) in graded-MQW-LED is due to the improvement in carrier uniformity and radiative recombination rate, consistent with the numerical simulation.

  7. Monte Carlo simulation of scatter in non-uniform symmetrical attenuating media for point and distributed sources

    International Nuclear Information System (INIS)

    Henry, L.J.; Rosenthal, M.S.

    1992-01-01

    We report results of scatter simulations for both point and distributed sources of 99m Tc in symmetrical non-uniform attenuating media. The simulations utilized Monte Carlo techniques and were tested against experimental phantoms. Both point and ring sources were used inside a 10.5 cm radius acrylic phantom. Attenuating media consisted of combinations of water, ground beef (to simulate muscle mass), air and bone meal (to simulate bone mass). We estimated/measured energy spectra, detector efficiencies and peak height ratios for all cases. In all cases, the simulated spectra agree with the experimentally measured spectra within 2 SD. Detector efficiencies and peak height ratios also are in agreement. The Monte Carlo code is able to properly model the non-uniform attenuating media used in this project. With verification of the simulations, it is possible to perform initial evaluation studies of scatter correction algorithms by evaluating the mechanisms of action of the correction algorithm on the simulated spectra where the magnitude and sources of scatter are known. (author)

  8. Uniform random number generators

    Science.gov (United States)

    Farr, W. R.

    1971-01-01

    Methods are presented for the generation of random numbers with uniform and normal distributions. Subprogram listings of Fortran generators for the Univac 1108, SDS 930, and CDC 3200 digital computers are also included. The generators are of the mixed multiplicative type, and the mathematical method employed is that of Marsaglia and Bray.

  9. Evaluation model development for sprinkler irrigation uniformity ...

    African Journals Online (AJOL)

    A new evaluation method with accompanying software was developed to precisely calculate uniformity from catch-can test data, assuming sprinkler distribution data to be a continuous variable. Two interpolation steps are required to compute unknown water application depths at grid distribution points from radial ...

  10. Uniformity across 200 mm silicon wafers printed by nanoimprint lithography

    International Nuclear Information System (INIS)

    Gourgon, C; Perret, C; Tallal, J; Lazzarino, F; Landis, S; Joubert, O; Pelzer, R

    2005-01-01

    Uniformity of the printing process is one of the key parameters of nanoimprint lithography. This technique has to be extended to large size wafers to be useful for several industrial applications, and the uniformity of micro and nanostructures has to be guaranteed on large surfaces. This paper presents results of printing on 200 mm diameter wafers. The residual thickness uniformity after printing is demonstrated at the wafer scale in large patterns (100 μm), in smaller lines of 250 nm and in sub-100 nm features. We show that a mould deformation occurs during the printing process, and that this deformation is needed to guarantee printing uniformity. However, the mould deformation is also responsible for the potential degradation of the patterns

  11. Assessment of 12 CHF prediction methods, for an axially non-uniform heat flux distribution, with the RELAP5 computer code

    Energy Technology Data Exchange (ETDEWEB)

    Ferrouk, M. [Laboratoire du Genie Physique des Hydrocarbures, University of Boumerdes, Boumerdes 35000 (Algeria)], E-mail: m_ferrouk@yahoo.fr; Aissani, S. [Laboratoire du Genie Physique des Hydrocarbures, University of Boumerdes, Boumerdes 35000 (Algeria); D' Auria, F.; DelNevo, A.; Salah, A. Bousbia [Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione, Universita di Pisa (Italy)

    2008-10-15

    The present article covers the evaluation of the performance of twelve critical heat flux methods/correlations published in the open literature. The study concerns the simulation of an axially non-uniform heat flux distribution with the RELAP5 computer code in a single boiling water reactor channel benchmark problem. The nodalization scheme employed for the considered particular geometry, as modelled in RELAP5 code, is described. For this purpose a review of critical heat flux models/correlations applicable to non-uniform axial heat profile is provided. Simulation results using the RELAP5 code and those obtained from our computer program, based on three type predictions methods such as local conditions, F-factor and boiling length average approaches were compared.

  12. Synthetic approaches to uniform polymers.

    Science.gov (United States)

    Ali, Monzur; Brocchini, Steve

    2006-12-30

    Uniform polymers are characterised by a narrow molecular weight distribution (MWD). Uniformity is also defined by chemical structure in respect of (1) monomer orientation, sequence and stereo-regularity, (2) polymer shape and morphology and (3) chemical functionality. The function of natural polymers such as polypeptides and polynucleotides is related to their conformational structure (e.g. folded tertiary structure). This is only possible because of their high degree of uniformity. While completely uniform synthetic polymers are rare, polymers with broad structure and MWD are widely used in medicine and the biomedical sciences. They are integral components in final dosage forms, drug delivery systems (DDS) and in implantable devices. Increasingly uniform polymers are being used to develop more complex medicines (e.g. delivery of biopharmaceuticals, enhanced formulations or DDS's for existing actives). In addition to the function imparted by any new polymer it will be required to meet stringent specifications in terms of cost containment, scalability, biocompatibility and performance. Synthetic polymers with therapeutic activity are also being developed to exploit their polyvalent properties, which is not possible with low molecular weight molecules. There is need to utilise uniform polymers for applications where the polymer may interact with the systemic circulation, tissues or cellular environment. There are also potential applications (e.g. stimuli responsive coatings) where uniform polymers may be used for their more defined property profile. While it is not yet practical to prepare synthetic polymers to the same high degree of uniformity as proteins, nature also effectively utilises many polymers with lower degrees of uniformity (e.g. polysaccharides, poly(amino acids), polyhydroxyalkanoates). In recent years it has become possible to prepare with practical experimental protocols sufficient quantities of polymers that display many aspects of uniformity. This

  13. Phylogenetic distribution of large-scale genome patchiness

    Directory of Open Access Journals (Sweden)

    Hackenberg Michael

    2008-04-01

    Full Text Available Abstract Background The phylogenetic distribution of large-scale genome structure (i.e. mosaic compositional patchiness has been explored mainly by analytical ultracentrifugation of bulk DNA. However, with the availability of large, good-quality chromosome sequences, and the recently developed computational methods to directly analyze patchiness on the genome sequence, an evolutionary comparative analysis can be carried out at the sequence level. Results The local variations in the scaling exponent of the Detrended Fluctuation Analysis are used here to analyze large-scale genome structure and directly uncover the characteristic scales present in genome sequences. Furthermore, through shuffling experiments of selected genome regions, computationally-identified, isochore-like regions were identified as the biological source for the uncovered large-scale genome structure. The phylogenetic distribution of short- and large-scale patchiness was determined in the best-sequenced genome assemblies from eleven eukaryotic genomes: mammals (Homo sapiens, Pan troglodytes, Mus musculus, Rattus norvegicus, and Canis familiaris, birds (Gallus gallus, fishes (Danio rerio, invertebrates (Drosophila melanogaster and Caenorhabditis elegans, plants (Arabidopsis thaliana and yeasts (Saccharomyces cerevisiae. We found large-scale patchiness of genome structure, associated with in silico determined, isochore-like regions, throughout this wide phylogenetic range. Conclusion Large-scale genome structure is detected by directly analyzing DNA sequences in a wide range of eukaryotic chromosome sequences, from human to yeast. In all these genomes, large-scale patchiness can be associated with the isochore-like regions, as directly detected in silico at the sequence level.

  14. Generation of uniformly distributed dose points for anatomy-based three-dimensional dose optimization methods in brachytherapy.

    Science.gov (United States)

    Lahanas, M; Baltas, D; Giannouli, S; Milickovic, N; Zamboglou, N

    2000-05-01

    We have studied the accuracy of statistical parameters of dose distributions in brachytherapy using actual clinical implants. These include the mean, minimum and maximum dose values and the variance of the dose distribution inside the PTV (planning target volume), and on the surface of the PTV. These properties have been studied as a function of the number of uniformly distributed sampling points. These parameters, or the variants of these parameters, are used directly or indirectly in optimization procedures or for a description of the dose distribution. The accurate determination of these parameters depends on the sampling point distribution from which they have been obtained. Some optimization methods ignore catheters and critical structures surrounded by the PTV or alternatively consider as surface dose points only those on the contour lines of the PTV. D(min) and D(max) are extreme dose values which are either on the PTV surface or within the PTV. They must be avoided for specification and optimization purposes in brachytherapy. Using D(mean) and the variance of D which we have shown to be stable parameters, achieves a more reliable description of the dose distribution on the PTV surface and within the PTV volume than does D(min) and D(max). Generation of dose points on the real surface of the PTV is obligatory and the consideration of catheter volumes results in a realistic description of anatomical dose distributions.

  15. Downsampling Non-Uniformly Sampled Data

    Directory of Open Access Journals (Sweden)

    Fredrik Gustafsson

    2007-10-01

    Full Text Available Decimating a uniformly sampled signal a factor D involves low-pass antialias filtering with normalized cutoff frequency 1/D followed by picking out every Dth sample. Alternatively, decimation can be done in the frequency domain using the fast Fourier transform (FFT algorithm, after zero-padding the signal and truncating the FFT. We outline three approaches to decimate non-uniformly sampled signals, which are all based on interpolation. The interpolation is done in different domains, and the inter-sample behavior does not need to be known. The first one interpolates the signal to a uniformly sampling, after which standard decimation can be applied. The second one interpolates a continuous-time convolution integral, that implements the antialias filter, after which every Dth sample can be picked out. The third frequency domain approach computes an approximate Fourier transform, after which truncation and IFFT give the desired result. Simulations indicate that the second approach is particularly useful. A thorough analysis is therefore performed for this case, using the assumption that the non-uniformly distributed sampling instants are generated by a stochastic process.

  16. Uniform irradiation of irregularly shaped cavities for photodynamic therapy

    NARCIS (Netherlands)

    Rem, A. I.; van Gemert, M. J.; van der Meulen, F. W.; Gijsbers, G. H.; Beek, J. F.

    1997-01-01

    It is difficult to achieve a uniform light distribution in irregularly shaped cavities. We have conducted a study on the use of hollow 'integrating' moulds for more uniform light delivery of photodynamic therapy in irregularly shaped cavities such as the oral cavity. Simple geometries such as a

  17. Plasma sheath physics and dose uniformity in enhanced glow discharge plasma immersion ion implantation and deposition

    International Nuclear Information System (INIS)

    Li Liuhe; Li Jianhui; Kwok, Dixon T. K.; Chu, Paul K.; Wang Zhuo

    2009-01-01

    Based on the multiple-grid particle-in-cell code, an advanced simulation model is established to study the sheath physics and dose uniformity along the sample stage in order to provide the theoretical basis for further improvement of enhanced glow discharge plasma immersion ion implantation and deposition. At t=7.0 μs, the expansion of the sheath in the horizontal direction is hindered by the dielectric cage. The electron focusing effect is demonstrated by this model. Most of the ions at the inside wall of the cage are implanted into the edge of the sample stage and a relatively uniform ion fluence distribution with a large peak is observed at the end. Compared to the results obtained from the previous model, a higher implant fluence and larger area of uniformity are disclosed.

  18. Production of titanium alloys with uniform distribution of heat resisting metals

    International Nuclear Information System (INIS)

    Reznichenko, V.A.; Goncharenko, T.V.; Khalimov, F.B.; Vojtechova, E.A.

    1976-01-01

    Consideration is given to the process of the formation of a titanium sponge alloyed with niobium or tantalum, in the joint metallic reduction of titanium, niobium and tantanum chlorides. A percentage composition of the phases observed and the structure of the alloyed sponge have been studied. It is shown that after one remelting operation of the alloyed sponge the alloys of titanium with niobium and tantalum have a uniform component distribution. At the stage of chloride reduction there appear solid solutions based on titanium and an alloying component. The stage of vacuum separation of the reaction mass is associated with a mutual dissolution of the primary phases and the formation of the solid solutions of the alloyed titanium sponge, which, by their composition, are close to the desired alloy composition. The principal features of the formation of a titanium sponge alloyed with niobium and tantalum are in a perfect agreemet with those typical of Ti-Mo and Ti-W sponges, therefore it can be assumed that these features will be also common to the other cases of the metallic reduction of titanium and refractory metals chlorides

  19. Production of titanium alloys with uniform distribution of heat resisting metals

    Energy Technology Data Exchange (ETDEWEB)

    Reznichenko, V A; Goncharenko, T V; Khalimov, F B; Voitechova, E A

    1976-01-01

    Consideration is given to the process of the formation of a titanium sponge alloyed with niobium or tantalum, in the joint metallic reduction of titanium, niobium and tantanum chlorides. A percentage composition of the phases observed and the structure of the alloyed sponge have been studied. It is shown that after one remelting operation of the alloyed sponge the alloys of titanium with niobium and tantalum have a uniform component distribution. At the stage of chloride reduction there appear solid solutions based on titanium and an alloying component. The stage of vacuum separation of the reaction mass is associated with a mutual dissolution of the primary phases and the formation of the solid solutions of the alloyed titanium sponge, which, by their composition, are close to the desired alloy composition. The principal features of the formation of a titanium sponge alloyed with niobium and tantalum are in a perfect agreemet with those typical of Ti-Mo and Ti-W sponges, therefore it can be assumed that these features will be also common to the other cases of the metallic reduction of titanium and refractory metals chlorides.

  20. Enhanced 2D-DOA Estimation for Large Spacing Three-Parallel Uniform Linear Arrays

    Directory of Open Access Journals (Sweden)

    Dong Zhang

    2018-01-01

    Full Text Available An enhanced two-dimensional direction of arrival (2D-DOA estimation algorithm for large spacing three-parallel uniform linear arrays (ULAs is proposed in this paper. Firstly, we use the propagator method (PM to get the highly accurate but ambiguous estimation of directional cosine. Then, we use the relationship between the directional cosine to eliminate the ambiguity. This algorithm not only can make use of the elements of the three-parallel ULAs but also can utilize the connection between directional cosine to improve the estimation accuracy. Besides, it has satisfied estimation performance when the elevation angle is between 70° and 90° and it can automatically pair the estimated azimuth and elevation angles. Furthermore, it has low complexity without using any eigen value decomposition (EVD or singular value decompostion (SVD to the covariance matrix. Simulation results demonstrate the effectiveness of our proposed algorithm.

  1. ACORN—A new method for generating sequences of uniformly distributed Pseudo-random Numbers

    Science.gov (United States)

    Wikramaratna, R. S.

    1989-07-01

    A new family of pseudo-random number generators, the ACORN ( additive congruential random number) generators, is proposed. The resulting numbers are distributed uniformly in the interval [0, 1). The ACORN generators are defined recursively, and the ( k + 1)th order generator is easily derived from the kth order generator. Some theorems concerning the period length are presented and compared with existing results for linear congruential generators. A range of statistical tests are applied to the ACORN generators, and their performance is compared with that of the linear congruential generators and the Chebyshev generators. The tests show the ACORN generators to be statistically superior to the Chebyshev generators, while being statistically similar to the linear congruential generators. However, the ACORN generators execute faster than linear congruential generators for the same statistical faithfulness. The main advantages of the ACORN generator are speed of execution, long period length, and simplicity of coding.

  2. Aging transition in systems of oscillators with global distributed-delay coupling.

    Science.gov (United States)

    Rahman, B; Blyuss, K B; Kyrychko, Y N

    2017-09-01

    We consider a globally coupled network of active (oscillatory) and inactive (nonoscillatory) oscillators with distributed-delay coupling. Conditions for aging transition, associated with suppression of oscillations, are derived for uniform and gamma delay distributions in terms of coupling parameters and the proportion of inactive oscillators. The results suggest that for the uniform distribution increasing the width of distribution for the same mean delay allows aging transition to happen for a smaller coupling strength and a smaller proportion of inactive elements. For gamma distribution with sufficiently large mean time delay, it may be possible to achieve aging transition for an arbitrary proportion of inactive oscillators, as long as the coupling strength lies in a certain range.

  3. Advanced air distribution

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor

    2011-01-01

    The aim of total volume air distribution (TVAD) involves achieving uniform temperature and velocity in the occupied zone and environment designed for an average occupant. The supply of large amounts of clean and cool air are needed to maintain temperature and pollution concentration at acceptable...... levels in the entire space, leading to increased energy consumption and the use of large and costly HVAC and duct systems. The performance of desk installed PV combined with background TVAD used for room temperature control has been studied in an office building located in a hot and humid climate....... Ventilation in hospitals is essential to decrease the risk of airborne cross-infection. At present, mixing air distribution at a minimum of 12 ach is used in infection wards. Advanced air distribution has the potential to aid in achieving healthy, comfortable and productive indoor environments at levels...

  4. Large-size, high-uniformity, random silver nanowire networks as transparent electrodes for crystalline silicon wafer solar cells.

    Science.gov (United States)

    Xie, Shouyi; Ouyang, Zi; Jia, Baohua; Gu, Min

    2013-05-06

    Metal nanowire networks are emerging as next generation transparent electrodes for photovoltaic devices. We demonstrate the application of random silver nanowire networks as the top electrode on crystalline silicon wafer solar cells. The dependence of transmittance and sheet resistance on the surface coverage is measured. Superior optical and electrical properties are observed due to the large-size, highly-uniform nature of these networks. When applying the nanowire networks on the solar cells with an optimized two-step annealing process, we achieved as large as 19% enhancement on the energy conversion efficiency. The detailed analysis reveals that the enhancement is mainly caused by the improved electrical properties of the solar cells due to the silver nanowire networks. Our result reveals that this technology is a promising alternative transparent electrode technology for crystalline silicon wafer solar cells.

  5. Explosive force of primacord grid forms large sheet metal parts

    Science.gov (United States)

    1966-01-01

    Primacord which is woven through fish netting in a grid pattern is used for explosive forming of large sheet metal parts. The explosive force generated by the primacord detonation is uniformly distributed over the entire surface of the sheet metal workpiece.

  6. Research on Fault Prediction of Distribution Network Based on Large Data

    Directory of Open Access Journals (Sweden)

    Jinglong Zhou

    2017-01-01

    Full Text Available With the continuous development of information technology and the improvement of distribution automation level. Especially, the amount of on-line monitoring and statistical data is increasing, and large data is used data distribution system, describes the technology to collect, data analysis and data processing of the data distribution system. The artificial neural network mining algorithm and the large data are researched in the fault diagnosis and prediction of the distribution network.

  7. Optimal threshold of error decision related to non-uniform phase distribution QAM signals generated from MZM based on OCS

    Science.gov (United States)

    Han, Xifeng; Zhou, Wen

    2018-03-01

    Optical vector radio-frequency (RF) signal generation based on optical carrier suppression (OCS) in one Mach-Zehnder modulator (MZM) can realize frequency-doubling. In order to match the phase or amplitude of the recovered quadrature amplitude modulation (QAM) signal, phase or amplitude pre-coding is necessary in the transmitter side. The detected QAM signals usually have one non-uniform phase distribution after square-law detection at the photodiode because of the imperfect characteristics of the optical and electrical devices. We propose to use optimal threshold of error decision for non-uniform phase contribution to reduce the bit error rate (BER). By employing this scheme, the BER of 16 Gbaud (32 Gbit/s) quadrature-phase-shift-keying (QPSK) millimeter wave signal at 36 GHz is improved from 1 × 10-3 to 1 × 10-4 at - 4 . 6 dBm input power into the photodiode.

  8. Uniform access to clinical data in a distributed environment. Radiology

    International Nuclear Information System (INIS)

    Adelhard, K.; Swoboda, N.; Nissen-Meyer, S.; Reiser, M.

    1999-01-01

    Purpose: Providing medical reports on wards and ambulatory settings in electronic form can improve the quality of health care delivery. Radiology was chosen as an example to demonstrate how to implement uniform access to clinical data in a hospital. Method: Medical professionals at the university hospital in Munich, Grosshadern, have access to all radiological reports of their patients. Web browsers are used as a front end. A centralized administration of users and patients is in place. Results: Centralized access control and patient selection guarantee uniform access to all applicable data via intranet and controls access rights. The high acceptance of this service is reflected by the high number of 150 requests per day. Discussion: Access to radiological reports within the Grosshadern University Clinics was enabled via web browsers in a short time. The high acceptance of the system also proves its easy use. Integration of the system in a centralized user and patient identification system supports the unified access to clinical data. (orig.) [de

  9. Weighted backprojection implemented with a non-uniform attenuation map for improved SPECT quantitation

    International Nuclear Information System (INIS)

    Manglos, S.H.; Jaszczak, R.J.; Floyd, C.E.

    1988-01-01

    A method is developed to improve quantitation in SPECT imaging by using an attenuation compensation method which includes the correct non-uniform attenuation spatial distribution (''map''). The method is based on the technique of weighted back projection, previously developed for uniform attenuation. The method is tested by imaging a non-uniform phantom, reconstructing with the known attenuation map, and quantitatively comparing the resultant image with the known activity distribution. Reconstructed image profiles are dramatically improved in comparison to reconstructions without compensation or with an assumed uniform attenuation map. Contrast measurements further quantify the improvement. Line spread function distortions seen previously in non-uniform geometries are essentially eliminated by the method. Therefore, the method appears to be appropriate for these geometries, if the non-uniform map can be determined. Some additional image distortions introduced by the compensation method are noted and will require further study

  10. Non-uniform temperature field measurement and simulation of a radio telescope’s main reflector under solar radiation

    International Nuclear Information System (INIS)

    Chen, Deshen; Qian, Hongliang; Wang, Huajie; Zhang, Gang; Fan, Feng; Shen, Shizhao

    2017-01-01

    Highlights: • Solar non-uniform temperature field test of a telescope’s reflector is conducted initially. • Time-varying distribution regularities are analyzed contrastively. • Simulation methods are proposed involving environmental factors and self-shadowing. • Refined discrimination method for the shadow distribution is put forward. • Validity of simulation methods is evaluated with the experimental data. - Abstract: To improve the ability of deep-space exploration, many astronomers around the world are actively engaged in the construction of large-aperture and high-precision radio telescopes. The temperature effect is one of three main factors affecting the reflector accuracy of radio telescopes. To study the daily non-uniform temperature field of the main reflector, experimental studies are first carried out with a 3-m-aperture radio telescope model. According to the test results for 16 working conditions, the distribution rule and time-varying regularity of the daily temperature field are summarized initially. Next, theoretical methods for the temperature field of the main reflector are studied considering multiple environmental parameters and self-shadows. Finally, the validity of the theoretical methods is evaluated with test results. The experimental study demonstrates that the non-uniform temperature distribution of the main reflector truly exists and should not be overlooked, and that the theoretical methods for the reflector temperature field proposed in this paper are effective. The research methods and conclusions can provide valuable references for thermal design, monitoring and control of similar high-precision radio telescopes.

  11. Uniform hexagonal graphene flakes and films grown on liquid copper surface.

    Science.gov (United States)

    Geng, Dechao; Wu, Bin; Guo, Yunlong; Huang, Liping; Xue, Yunzhou; Chen, Jianyi; Yu, Gui; Jiang, Lang; Hu, Wenping; Liu, Yunqi

    2012-05-22

    Unresolved problems associated with the production of graphene materials include the need for greater control over layer number, crystallinity, size, edge structure and spatial orientation, and a better understanding of the underlying mechanisms. Here we report a chemical vapor deposition approach that allows the direct synthesis of uniform single-layered, large-size (up to 10,000 μm(2)), spatially self-aligned, and single-crystalline hexagonal graphene flakes (HGFs) and their continuous films on liquid Cu surfaces. Employing a liquid Cu surface completely eliminates the grain boundaries in solid polycrystalline Cu, resulting in a uniform nucleation distribution and low graphene nucleation density, but also enables self-assembly of HGFs into compact and ordered structures. These HGFs show an average two-dimensional resistivity of 609 ± 200 Ω and saturation current density of 0.96 ± 0.15 mA/μm, demonstrating their good conductivity and capability for carrying high current density.

  12. Modelling refrigerant distribution in minichannel evaporators

    DEFF Research Database (Denmark)

    Brix, Wiebke

    of the liquid and vapour in the inlet manifold. Combining non-uniform airflow and non-uniform liquid and vapour distribution shows that a non-uniform airflow distribution to some degree can be compensated by a suitable liquid and vapour distribution. Controlling the superheat out of the individual channels...... to be equal, results in a cooling capacity very close to the optimum. A sensitivity study considering parameter changes shows that the course of the pressure gradient in the channel is significant, considering the magnitude of the capacity reductions due to non-uniform liquid and vapour distribution and non......This thesis is concerned with numerical modelling of flow distribution in a minichannel evaporator for air-conditioning. The study investigates the impact of non-uniform airflow and non-uniform distribution of the liquid and vapour phases in the inlet manifold on the refrigerant mass flow...

  13. Top-k aggregation queries in large-scale distributed systems

    OpenAIRE

    Michel, Sebastian

    2007-01-01

    Distributed top-k query processing has recently become an essential functionality in a large number of emerging application classes like Internet traffic monitoring and Peer-to-Peer Web search. This work addresses efficient algorithms for distributed top-k queries in wide-area networks where the index lists for the attribute values (or text terms) of a query are distributed across a number of data peers. More precisely, in this thesis, we make the following distributions: We present the fa...

  14. Quantitative SPECT reconstruction for brain distribution with a non-uniform attenuation using a regularizing method

    International Nuclear Information System (INIS)

    Soussaline, F.; Bidaut, L.; Raynaud, C.; Le Coq, G.

    1983-06-01

    An analytical solution to the SPECT reconstruction problem, where the actual attenuation effect can be included, was developped using a regularizing iterative method (RIM). The potential of this approach in quantitative brain studies when using a tracer for cerebrovascular disorders is now under evaluation. Mathematical simulations for a distributed activity in the brain surrounded by the skull and physical phantom studies were performed, using a rotating camera based SPECT system, allowing the calibration of the system and the evaluation of the adapted method to be used. On the simulation studies, the contrast obtained along a profile, was less than 5%, the standard deviation 8% and the quantitative accuracy 13%, for a uniform emission distribution of mean = 100 per pixel and a double attenuation coefficient of μ = 0.115 cm -1 and 0.5 cm -1 . Clinical data obtained after injection of 123 I (AMPI) were reconstructed using the RIM without and with cerebrovascular diseases or lesion defects. Contour finding techniques were used for the delineation of the brain and the skull, and measured attenuation coefficients were assumed within these two regions. Using volumes of interest, selected on homogeneous regions on an hemisphere and reported symetrically, the statistical uncertainty for 300 K events in the tomogram was found to be 12%, the index of symetry was of 4% for normal distribution. These results suggest that quantitative SPECT reconstruction for brain distribution is feasible, and that combined with an adapted tracer and an adequate model physiopathological parameters could be extracted

  15. Optical design of soft multifocal contact lens with uniform optical power in center-distance zone with optimized NURBS.

    Science.gov (United States)

    Vu, Lien T; Chen, Chao-Chang A; Yu, Chia-Wei

    2018-02-05

    This study aims to develop a new optical design method of soft multifocal contact lens (CLs) to obtain uniform optical power in large center-distance zone with optimized Non-Uniform Rational B-spline (NURBS). For the anterior surface profiles of CLs, the NURBS design curves are optimized to match given optical power distributions. Then, the NURBS in the center-distance zones are fitted in the corresponding spherical/aspheric curves for both data points and their centers of curvature to achieve the uniform power. Four cases of soft CLs have been manufactured by casting in shell molds by injection molding and then measured to verify the design specifications. Results of power profiles of these CLs are concord with the given clinical requirements of uniform powers in larger center-distance zone. The developed optical design method has been verified for multifocal CLs design and can be further applied for production of soft multifocal CLs.

  16. Rolling Force Prediction in Heavy Plate Rolling Based on Uniform Differential Neural Network

    Directory of Open Access Journals (Sweden)

    Fei Zhang

    2016-01-01

    Full Text Available Accurate prediction of the rolling force is critical to assuring the quality of the final product in steel manufacturing. Exit thickness of plate for each pass is calculated from roll gap, mill spring, and predicted roll force. Ideal pass scheduling is dependent on a precise prediction of the roll force in each pass. This paper will introduce a concept that allows obtaining the material model parameters directly from the rolling process on an industrial scale by the uniform differential neural network. On the basis of the characteristics that the uniform distribution can fully characterize the solution space and enhance the diversity of the population, uniformity research on differential evolution operator is made to get improved crossover with uniform distribution. When its original function is transferred with a transfer function, the uniform differential evolution algorithms can quickly solve complex optimization problems. Neural network structure and weights threshold are optimized by uniform differential evolution algorithm, and a uniform differential neural network is formed to improve rolling force prediction accuracy in process control system.

  17. Irradiation uniformity of spherical targets by multiple uv beams from OMEGA

    International Nuclear Information System (INIS)

    Beich, W.; Dunn, M.; Hutchison, R.

    1984-01-01

    Direct-drive laser fusion demands extremely high levels of irradiation uniformity to ensure uniform compression of spherical targets. The assessment of illumination uniformity of targets irradiated by multiple beams from the OMEGA facility is made with the aid of multiple beams spherical superposition codes, which take into account ray tracing and absorption and a detailed knowledge of the intensity distribution of each beam in the target plane. In this report, recent estimates of the irradiation uniformity achieved with 6 and 12 uv beams of OMEGA will be compared with previous measurements in the IR, and predictions will be made for the uv illumination uniformity achievable with 24 beams of OMEGA

  18. Optimizing the LSST Dither Pattern for Survey Uniformity

    Science.gov (United States)

    Awan, Humna; Gawiser, Eric J.; Kurczynski, Peter; Carroll, Christopher M.; LSST Dark Energy Science Collaboration

    2015-01-01

    The Large Synoptic Survey Telescope (LSST) will gather detailed data of the southern sky, enabling unprecedented study of Baryonic Acoustic Oscillations, which are an important probe of dark energy. These studies require a survey with highly uniform depth, and we aim to find an observation strategy that optimizes this uniformity. We have shown that in the absence of dithering (large telescope-pointing offsets), the LSST survey will vary significantly in depth. Hence, we implemented various dithering strategies, including random and repulsive random pointing offsets and spiral patterns with the spiral reaching completion in either a few months or the entire ten-year run. We employed three different implementations of dithering strategies: a single offset assigned to all fields observed on each night, offsets assigned to each field independently whenever the field is observed, and offsets assigned to each field only when the field is observed on a new night. Our analysis reveals that large dithers are crucial to guarantee survey uniformity and that assigning dithers to each field independently whenever the field is observed significantly increases this uniformity. These results suggest paths towards an optimal observation strategy that will enable LSST to achieve its science goals.We gratefully acknowledge support from the National Science Foundation REU program at Rutgers, PHY-1263280, and the Department of Energy, DE-SC0011636.

  19. Optimization of the plasma parameters for the high current and uniform large-scale pulse arc ion source of the VEST-NBI system

    International Nuclear Information System (INIS)

    Jung, Bongki; Park, Min; Heo, Sung Ryul; Kim, Tae-Seong; Jeong, Seung Ho; Chang, Doo-Hee; Lee, Kwang Won; In, Sang-Ryul

    2016-01-01

    Highlights: • High power magnetic bucket-type arc plasma source for the VEST NBI system is developed with modifications based on the prototype plasma source for KSTAR. • Plasma parameters in pulse duration are measured to characterize the plasma source. • High plasma density and good uniformity is achieved at the low operating pressure below 1 Pa. • Required ion beam current density is confirmed by analysis of plasma parameters and results of a particle balance model. - Abstract: A large-scale hydrogen arc plasma source was developed at the Korea Atomic Energy Research Institute for a high power pulsed NBI system of VEST which is a compact spherical tokamak at Seoul national university. One of the research target of VEST is to study innovative tokamak operating scenarios. For this purpose, high current density and uniform large-scale pulse plasma source is required to satisfy the target ion beam power efficiently. Therefore, optimizing the plasma parameters of the ion source such as the electron density, temperature, and plasma uniformity is conducted by changing the operating conditions of the plasma source. Furthermore, ion species of the hydrogen plasma source are analyzed using a particle balance model to increase the monatomic fraction which is another essential parameter for increasing the ion beam current density. Conclusively, efficient operating conditions are presented from the results of the optimized plasma parameters and the extractable ion beam current is calculated.

  20. Divergence from, and Convergence to, Uniformity of Probability Density Quantiles

    Directory of Open Access Journals (Sweden)

    Robert G. Staudte

    2018-04-01

    Full Text Available We demonstrate that questions of convergence and divergence regarding shapes of distributions can be carried out in a location- and scale-free environment. This environment is the class of probability density quantiles (pdQs, obtained by normalizing the composition of the density with the associated quantile function. It has earlier been shown that the pdQ is representative of a location-scale family and carries essential information regarding shape and tail behavior of the family. The class of pdQs are densities of continuous distributions with common domain, the unit interval, facilitating metric and semi-metric comparisons. The Kullback–Leibler divergences from uniformity of these pdQs are mapped to illustrate their relative positions with respect to uniformity. To gain more insight into the information that is conserved under the pdQ mapping, we repeatedly apply the pdQ mapping and find that further applications of it are quite generally entropy increasing so convergence to the uniform distribution is investigated. New fixed point theorems are established with elementary probabilistic arguments and illustrated by examples.

  1. Analytical modeling of large amplitude free vibration of non-uniform beams carrying a both transversely and axially eccentric tip mass

    Science.gov (United States)

    Malaeke, Hasan; Moeenfard, Hamid

    2016-03-01

    The objective of this paper is to study large amplitude flexural-extensional free vibration of non-uniform cantilever beams carrying a both transversely and axially eccentric tip mass. The effects of variable axial force is also taken into account. Hamilton's principle is utilized to obtain the partial differential equations governing the nonlinear vibration of the system as well as the corresponding boundary conditions. A numerical finite difference scheme is proposed to find the natural frequencies and mode shapes of the system which is validated specifically for a beam with linearly varying cross section. Using a single mode approximation in conjunction with the Lagrange method, the governing equations are reduced to a set of two nonlinear ordinary differential equations in terms of end displacement components of the beam which are coupled due to the presence of the transverse eccentricity. These temporal coupled equations are then solved analytically using the multiple time scales perturbation technique. The obtained analytical results are compared with the numerical ones and excellent agreement is observed. The qualitative and quantitative knowledge resulting from this research is expected to enable the study of the effects of eccentric tip mass and non-uniformity on the large amplitude flexural-extensional vibration of beams for improved dynamic performance.

  2. Novel attempt to create uniform magnetic-field space generated by face-to-face settled HTS bulk magnets

    International Nuclear Information System (INIS)

    Oka, Tetsuo; Ichiju, Kana; Higa, Kazuya; Fukui, Satoshi; Ogawa, Jun; Sato, Takao; Yokoyama, Kazuya; Nakamura, Takashi

    2017-01-01

    Various experimental attempts have been made to obtain a uniform magnetic field in the space between face-to-face HTS bulk magnets that could possibly be utilized as NMR magnets. In general, the magnetic fields emitted from the magnetic pole surfaces containing HTS bulk magnets are characterized as non-uniform field distributions. Since the NMR magnets require highly uniform magnetic-field spaces, it has been assumed to be difficult to form uniform magnetic-field spaces between magnetic poles placed face-to-face. The authors modified the shapes of the magnetic-field distribution from convex to concave by attaching ferromagnetic iron plates to the pole surfaces. The magnets were then set face-to-face with various gaps of 30-70 mm, and the experimental data on magnetic-field uniformity was precisely measured in the space. In order to detect the NMR signals, the target performance for uniformity was set as 1,500 ppm throughout the 4-mm span on the x-axis, which is equivalent to performance in the past when the world's first detection of NMR signals was observed in the bore of hollow-type HTS bulk magnets. When we combined the concave and convex field distributions to compensate the uneven field distributions, the data of the best uniformity reached 358 ppm and 493 ppm in the 30 mm and 50 mm gaps, respectively, which exceeded the target value for the purpose of detecting the NMR signals within the space. Furthermore, it was shown that the field distributions change from concave to convex shape without any change at 1.1 T in the range from 7 to 11 mm in the 30-mm gap, indicating that the distributions are uniform. This suggests the possibility that the uniform magnetic-field space between the HTS bulk magnets set face-to-face expands. (author)

  3. Preparation of uniform porous hydroxyapatite biomaterials by a new method

    International Nuclear Information System (INIS)

    Tang Yuejun; Tang Yuefeng; Lv Chuntang; Zhou Zhonghua

    2008-01-01

    In this paper, a new method of preparation of uniform porous hydroxyapatite biomaterials was reported. In order to obtain uniform porous biomaterials, disk samples were formed by the mixture of hydroxyapatite (HAP) powders and monodispersed polystyrene microspheres, and then HAP uniform porous materials with different diameter and different porosity (diameter: 436 ± 25 nm, 892 ± 20 nm and 1890 ± 20 nm, porosity: 46.5%, 41.3% and 34.7%, respectively) were prepared by sintering these disk samples at 1250 deg. C for 5 h. The pure phase of HAP powders fabricated by the hydrothermal technology was confirmed by X-ray diffraction (XRD). The surface and size distribution of pores in HAP biomaterials were observed by scanning electron microscopy (SEM), and the pore size distribution in porous HAP biomaterials was tested by mercury intrusion method

  4. Large-Scale Cooperative Task Distribution on Peer-to-Peer Networks

    Science.gov (United States)

    2012-01-01

    SUBTITLE Large-scale cooperative task distribution on peer-to-peer networks 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...disadvantages of ML- Chord are its fixed size (two layers), and limited scala - bility for large-scale systems. RC-Chord extends ML- D. Karrels et al...configurable before runtime. This can be improved by incorporating a distributed learning algorithm to tune the number and range of the DLoE tracking

  5. Uniform-related infection control practices of dental students

    Directory of Open Access Journals (Sweden)

    Aljohani Y

    2017-04-01

    Full Text Available Yazan Aljohani,1 Mohammed Almutadares,1 Khalid Alfaifi,1 Mona El Madhoun,1 Maysoon H Albahiti,2 Nadia Al-Hazmi3 1Internship Program, Faculty of dentistry, King Abdulaziz University, 2Department of Endodontics, King Abdulaziz University, 3Department of Oral Biology, King Abdulaziz University, Faculty of Dentistry, Jeddah, Saudi Arabia Background: Uniform-related infection control practices are sometimes overlooked and underemphasized. In Saudi Arabia, personal protective equipment must meet global standards for infection control, but the country’s Islamic legislature also needs to be taken into account. Aim: To assess uniform-related infection control practices of a group of dental students in a dental school in Saudi Arabia and compare the results with existing literature related to cross-contamination through uniforms in the dental field. Method: A questionnaire was formulated and distributed to dental students at King Abdulaziz University Faculty of Dentistry in Jeddah, Saudi Arabia, which queried the students about their uniform-related infection control practices and their methods and frequency of laundering and sanitizing their uniforms, footwear, and name tags. Results: There is a significant difference between genders with regard to daily uniform habits. The frequency of uniform washing was below the standard and almost 30% of students were not aware of how their uniforms are washed. Added to this, there is no consensus on a unified uniform for male and female students. Conclusion: Information on preventing cross-contamination through wearing uniforms must be supplied, reinforced, and emphasized while taking into consideration the cultural needs of the Saudi society. Keywords: cross-contamination, infection control, dental students, uniforms

  6. Two-dimensional hydrodynamics of uniform ion plasma in electrostatic field

    International Nuclear Information System (INIS)

    Mahdieh, M. H.; Gavili, A.

    2005-01-01

    Two-dimensional hydrodynamics of ion extraction from uniform quasi-neutral plasma, in electrostatic field has been simulated numerically. Experimentally, tunable pulsed lasers produce non-uniform plasma through stepwise photo-excitation and photo-ionization or multi-photo-ionization processes. Poisson's equation was solved simultaneously with the equations of mass, and momentum, assuming the Maxwell-Boltzmann distribution for electrons. In the calculation, the initial density profile at the boundaries has been assumed to be very steep for the ion plasma. In these calculations dynamics of electric potential and the ions density were assessed. The ion extraction time was also estimated from the calculation. The knowledge of spatial distribution of the ions across the cathode is very important for the practical purposes. In this simulation, the spatial distribution of the ion current density across the cathode as well as its temporal distribution was calculated

  7. Discrete method for design of flow distribution in manifolds

    International Nuclear Information System (INIS)

    Wang, Junye; Wang, Hualin

    2015-01-01

    Flow in manifold systems is encountered in designs of various industrial processes, such as fuel cells, microreactors, microchannels, plate heat exchanger, and radial flow reactors. The uniformity of flow distribution in manifold is a key indicator for performance of the process equipment. In this paper, a discrete method for a U-type arrangement was developed to evaluate the uniformity of the flow distribution and the pressure drop and then was used for direct comparisons between the U-type and the Z-type. The uniformity of the U-type is generally better than that of the Z-type in most of cases for small ζ and large M. The U-type and the Z-type approach each other as ζ increases or M decreases. However, the Z-type is more sensitive to structures than the U-type and approaches uniform flow distribution faster than the U-type as M decreases or ζ increases. This provides a simple yet powerful tool for the designers to evaluate and select a flow arrangement and offers practical measures for industrial applications. - Highlights: • Discrete methodology of flow field designs in manifolds with U-type arrangements. • Quantitative comparison between U-type and Z-type arrangements. • Discrete solution of flow distribution with varying flow coefficients. • Practical measures and guideline to design of manifold systems.

  8. On the statistics of the minimal solution of a linear Diophantine equation and uniform distribution of the real part of orbits in hyperbolic spaces

    DEFF Research Database (Denmark)

    Risager, Morten S.; Rudnick, Zeev

    We study a variant of a problem considered by Dinaburg and Sinai on the statistics of the minimal solution to a linear Diophantine equation. We show that the signed ratio between the Euclidean norms of the minimal solution and the coefficient vector is uniformly distributed modulo one. We reduce ...

  9. Non-uniform temperature gradients and thermal stresses produced ...

    Indian Academy of Sciences (India)

    thermally-induced stress distributions in a hollow steel sphere heated by a moving uniform ... models to evaluate temperatures according to the frictional heat generation, ... of these thermal effects include thermal stress, strain and deformation.

  10. The Ciliate Paramecium Shows Higher Motility in Non-Uniform Chemical Landscapes

    Science.gov (United States)

    Giuffre, Carl; Hinow, Peter; Vogel, Ryan; Ahmed, Tanvir; Stocker, Roman; Consi, Thomas R.; Strickler, J. Rudi

    2011-01-01

    We study the motility behavior of the unicellular protozoan Paramecium tetraurelia in a microfluidic device that can be prepared with a landscape of attracting or repelling chemicals. We investigate the spatial distribution of the positions of the individuals at different time points with methods from spatial statistics and Poisson random point fields. This makes quantitative the informal notion of “uniform distribution” (or lack thereof). Our device is characterized by the absence of large systematic biases due to gravitation and fluid flow. It has the potential to be applied to the study of other aquatic chemosensitive organisms as well. This may result in better diagnostic devices for environmental pollutants. PMID:21494596

  11. Direct access to mesoporous crystalline TiO2/carbon composites with large and uniform pores for use as anode materials in lithium ion batteries

    NARCIS (Netherlands)

    Lee, J.; Jung, Y.S.; Warren, S.C.; Kamperman, M.M.G.; Oh, S.M.; DiSalvo, F.J.; Wiesner, U.

    2011-01-01

    Mesoporous and highly crystalline TiO2 (anatase)/carbon composites with large (>5¿nm) and uniform pores were synthesized using PI-b-PEO block copolymers as structure directing agents. Pore sizes could be tuned by utilizing block copolymers with different molecular weights. The resulting

  12. Number theory Diophantine problems, uniform distribution and applications : festschrift in honour of Robert F. Tichy’s 60th birthday

    CERN Document Server

    Grabner, Peter

    2017-01-01

    This volume is dedicated to Robert F. Tichy on the occasion of his 60th birthday. Presenting 22 research and survey papers written by leading experts in their respective fields, it focuses on areas that align with Tichy’s research interests and which he significantly shaped, including Diophantine problems, asymptotic counting, uniform distribution and discrepancy of sequences (in theory and application), dynamical systems, prime numbers, and actuarial mathematics. Offering valuable insights into recent developments in these areas, the book will be of interest to researchers and graduate students engaged in number theory and its applications.

  13. Dynamic Uniform Scaling for Multiobjective Genetic Algorithms

    DEFF Research Database (Denmark)

    Pedersen, Gerulf; Goldberg, David E.

    2004-01-01

    Before Multiobjective Evolutionary Algorithms (MOEAs) can be used as a widespread tool for solving arbitrary real world problems there are some salient issues which require further investigation. One of these issues is how a uniform distribution of solutions along the Pareto non-dominated front c...

  14. Dynamic Uniform Scaling for Multiobjective Genetic Algorithms

    DEFF Research Database (Denmark)

    Pedersen, Gerulf; Goldberg, D.E.

    2004-01-01

    Before Multiobjective Evolutionary Algorithms (MOEAs) can be used as a widespread tool for solving arbitrary real world problems there are some salient issues which require further investigation. One of these issues is how a uniform distribution of solutions along the Pareto non-dominated front can...

  15. Study of light collection uniformity dependence on reflector type in a large scintillation counter

    International Nuclear Information System (INIS)

    Astvatsaturov, R.G.; Ivanov, V.I.; Knapik, E.; Kramarenko, V.A.; Malakhov, A.I.; Khachaturyan, M.N.

    1977-01-01

    An investigation of the way to improve uniformity of light collection onto photoelectric multiplier photocathode, for the 100x10x2 cm scintillation counter, has been undertaken. Pulse amplitude versus the point, particles strike a scintillator, relationship, has been demonstrated for several types of reflectors. Used as reflectors were: white papar, aluminium foil, black papar and a combination of above reflectors. Experimental data analysis shows, that the combination of reflectors with different reflection coefficient, provides a means for 1,5 time improvement of counter light collection uniformity, with no impairment of amplitude characteristics

  16. Stable and efficient retrospective 4D-MRI using non-uniformly distributed quasi-random numbers

    Science.gov (United States)

    Breuer, Kathrin; Meyer, Cord B.; Breuer, Felix A.; Richter, Anne; Exner, Florian; Weng, Andreas M.; Ströhle, Serge; Polat, Bülent; Jakob, Peter M.; Sauer, Otto A.; Flentje, Michael; Weick, Stefan

    2018-04-01

    The purpose of this work is the development of a robust and reliable three-dimensional (3D) Cartesian imaging technique for fast and flexible retrospective 4D abdominal MRI during free breathing. To this end, a non-uniform quasi random (NU-QR) reordering of the phase encoding (k y –k z ) lines was incorporated into 3D Cartesian acquisition. The proposed sampling scheme allocates more phase encoding points near the k-space origin while reducing the sampling density in the outer part of the k-space. Respiratory self-gating in combination with SPIRiT-reconstruction is used for the reconstruction of abdominal data sets in different respiratory phases (4D-MRI). Six volunteers and three patients were examined at 1.5 T during free breathing. Additionally, data sets with conventional two-dimensional (2D) linear and 2D quasi random phase encoding order were acquired for the volunteers for comparison. A quantitative evaluation of image quality versus scan times (from 70 s to 626 s) for the given sampling schemes was obtained by calculating the normalized mutual information (NMI) for all volunteers. Motion estimation was accomplished by calculating the maximum derivative of a signal intensity profile of a transition (e.g. tumor or diaphragm). The 2D non-uniform quasi-random distribution of phase encoding lines in Cartesian 3D MRI yields more efficient undersampling patterns for parallel imaging compared to conventional uniform quasi-random and linear sampling. Median NMI values of NU-QR sampling are the highest for all scan times. Therefore, within the same scan time 4D imaging could be performed with improved image quality. The proposed method allows for the reconstruction of motion artifact reduced 4D data sets with isotropic spatial resolution of 2.1  ×  2.1  ×  2.1 mm3 in a short scan time, e.g. 10 respiratory phases in only 3 min. Cranio-caudal tumor displacements between 23 and 46 mm could be observed. NU-QR sampling enables for stable 4D

  17. Improvement of illumination uniformity for LED flat panel light by using micro-secondary lens array.

    Science.gov (United States)

    Lee, Hsiao-Wen; Lin, Bor-Shyh

    2012-11-05

    LED flat panel light is an innovative lighting product in recent years. However, current flat panel light products still contain some drawbacks, such as narrow lighting areas and hot spots. In this study, a micro-secondary lens array technique was proposed and applied for the design of the light guide surface to improve the illumination uniformity. By using the micro-secondary lens array, the candela distribution of the LED flat panel light can be adjusted to similar to batwing distribution to improve the illumination uniformity. The experimental results show that the enhancement of the floor illumination uniformity is about 61%, and that of the wall illumination uniformity is about 20.5%.

  18. Evaluation of distribution coefficients for the prediction of strontium and cesium migration in a uniform sand

    International Nuclear Information System (INIS)

    Reynolds, W.D.; Gillham, R.W.; Cherry, J.A.

    1982-01-01

    The validity of using a distribution coefficient (Ksub(d)) in the mathematical prediction of strontium and cesium transport through uniform saturated sand was investigated by comparing measured breakthrough curves with curves of simulations using the advection-dispersion and the advection equations. Values for Ksub(d) were determined by batch equilibration tests and, indirectly, by fitting the mathematical model to breakthrough data from column experiments. Although the advection-dispersion equation accurately represented the breakthrough curves for two nonreactive solutes (chloride and tritium), neither it nor the advection equation provided close representations of the strontium and cesium curves. The simulated breakthrough curves for strontium and cesium were nearly symmetrical, whereas the data curves were very asymmetrical, with long tails. Column experiments with different pore-water velocities indicated that the shape of the normalized breakthrough curves was not sensitive to velocity. This suggests that the asymmetry of the measured curves was the result of nonlinear partitioning of the cations between the solid and liquid phases, rather than nonequilibrium effects. The results indicate that the distribution coefficient, when used in advection-dispersion models for prediction of the migration of strontium and cesium in field situations, can result in significant error

  19. ANTITRUST ISSUES IN THE LARGE-SCALE FOOD DISTRIBUTION SECTOR

    Directory of Open Access Journals (Sweden)

    Enrico Adriano Raffaelli

    2014-12-01

    Full Text Available In light of the slow modernization of the Italian large-scale food distribution sector, of the fragmentation at national level, of the significant roles of the cooperatives at local level and of the alliances between food retail chains, the ICA during the recent years has developed a strong interest in this sector.After having analyzed the peculiarities of the Italian large-scale food distribution sector, this article shows the recent approach taken by the ICA toward the main antitrust issues in this sector.In the analysis of such issues, mainly the contractual relations between the GDO retailers and their suppliers, the introduction of Article 62 of Law no. 27 dated 24th March 2012 is crucial, because, by facilitating and encouraging complaints by the interested parties, it should allow the developing of normal competitive dynamics within the food distribution sector, where companies should be free to enter the market using the tools at their disposal, without undue restrictions.

  20. Calculation of age-dependent dose conversion coefficients for radionuclides uniformly distributed in air

    International Nuclear Information System (INIS)

    Hung, Tran Van; Satoh, Daiki; Takahashi, Fumiaki; Tsuda, Shuichi; Endo, Akira; Saito, Kimiaki; Yamaguchi, Yasuhiro

    2005-02-01

    Age-dependent dose conversion coefficients for external exposure to photons emitted by radionuclides uniformly distributed in air were calculated. The size of the source region in the calculation was assumed to be effectively semi-infinite in extent. Firstly, organ doses were calculated with a series of age-specific MIRD-5 type phantoms using MCNP code, a Monte Carlo transport code. The calculations were performed for mono-energetic photon sources of twelve energies from 10 keV to 5 MeV and for phantoms of newborn, 1, 5, 10 and 15 years, and adult. Then, the effective doses to the different age-phantoms from the mono-energetic photon sources were estimated based on the obtained organ doses. The calculated effective doses were used to interpolate the conversion coefficients of the effective doses for 160 radionuclides, which are important for dose assessment of nuclear facilities. In the calculation, energies and intensities of emitted photons from radionuclides were taken from DECDC, a recent compilation of decay data for radiation dosimetry developed at JAERI. The results are tabulated in the form of effective dose per unit concentration and time (Sv per Bq s m -3 ). (author)

  1. The Consequence of Self-field and Non-uniform Current Distribution on Short Sample Tests of Superconducting Cables

    CERN Document Server

    Verweij, A P

    1998-01-01

    Electrical measurements on samples of superconducting cables are usually performed in order to determine the critical current $I_c$ and the n-value, assuming that the voltage U at the transition from the superconducting to the normal state follows the power law, U\\sim($I/I_c$)$^n$. An accurate measurement of $I_c$ and n demands, first of all, good control of temperature and field, and precise measurement of current and voltage. The critical current and n-value of a cable are influenced by the self-field of the cable, an effect that has to be known in order to compare the electrical characteristics of the cable with those of the strands from which it is made. The effect of the self-field is dealt with taking into account the orientation and magnitude of the applied field and the n-value of the strands. An important source of inaccuracy is related to the distribution of the currents among the strands. Non-uniform distributions, mainly caused by non-equal resistances of the connections between the strands of the...

  2. Method for uniformly distributing carbon flakes in a positive electrode, the electrode made thereby and compositions. [Patent application

    Science.gov (United States)

    Mrazek, F.C.; Smaga, J.A.; Battles, J.E.

    1981-01-19

    A positive electrode for a secondary electrochemical cell is described wherein an electrically conductive current collector is in electrical contact with a particulate mixture of gray cast iron and an alkali metal sulfide and an electrolyte including alkali metal halides or alkaline earth metal halides. Also present may be a transition metal sulfide and graphite flakes from the conversion of gray cast iron to iron sulfide. Also disclosed is a method of distributing carbon flakes in a cell wherein there is formed an electrochemical cell of a positive electrode structure of the type described and a suitable electrolyte and a second electrode containing a material capable of alloying with alkali metal ions. The cell is connected to a source of electrical potential to electrochemically convert gray cast iron to an iron sulfide and uniformly to distribute carbon flakes formerly in the gray cast iron throughout the positive electrode while forming an alkali metal alloy in the negative electrode. Also disclosed are compositions useful in preparing positive electrodes.

  3. A numerical model to evaluate the flow distribution in large solar collector fields in different operating conditions

    DEFF Research Database (Denmark)

    Bava, Federico; Dragsted, Janne; Furbo, Simon

    2017-01-01

    in different an-ay layouts. Balancing valves proved to he an effective way to achieve uniform flow distribution also in conditions different from those for which the valves were regulated, as well as in case of irregular layouts with different compositions of the collector rows. A Tichelmann connection gave...

  4. Large-aperture discharges in E-beam sustained CO2 amplifiers

    International Nuclear Information System (INIS)

    Leland, W.T.; Ganley, J.T.; Kircher, M.; York, G.W. Jr.

    1977-01-01

    The very large energy fluxes required for the attainment of scientific breakeven in laser-fusion experiments can only be obtained by the construction of multiple-beam, large-aperture lasers. Accordingly, the next generation CO 2 laser currently being designed at LASL consists of six electron-beam sustained amplifier modules, each module containing 12 large-aperture (approximately 30 x 30 cm) laser discharges sustained by (and surrounding) a single, cylindrical cold-cathode electron gun. The large scale and cylindrical geometry combine to generate substantial electric and magnetic field effects which can affect the uniformity of the electron-beam distribution, causing a number of difficulties including discharge and gain nonuniformities and potential arcing. In an effort to learn the magnitude of the associated difficulties and test various solutions for reducing the effects, a prototype module was constructed. This prototype was constructed full scale in the dimensions which will produce the discharge nonuniformities and measurements were made of the electron beam uniformity, discharge uniformity, and gain uniformity under a wide range of experimental conditions. These results indicate that under worse case conditions and nonuniformities, while severe, are within acceptable limits and can be reduced even further by minor design changes. Perhaps more importantly, calculational models have been developed which agree adequately enough with the data so that they can be used with reasonable confidence as a data base for predicting the performance of the final design of the amplifier modules and the effects of any changes which may be required

  5. Facile synthesis of uniform large-sized InP nanocrystal quantum dots using tris(tert-butyldimethylsilyl)phosphine

    Science.gov (United States)

    2012-01-01

    Colloidal III-V semiconductor nanocrystal quantum dots [NQDs] have attracted interest because they have reduced toxicity compared with II-VI compounds. However, the study and application of III-V semiconductor nanocrystals are limited by difficulties in their synthesis. In particular, it is difficult to control nucleation because the molecular bonds in III-V semiconductors are highly covalent. A synthetic approach of InP NQDs was presented using newly synthesized organometallic phosphorus [P] precursors with different functional moieties while preserving the P-Si bond. Introducing bulky side chains in our study improved the stability while facilitating InP formation with strong confinement at a readily low temperature regime (210°C to 300°C). Further shell coating with ZnS resulted in highly luminescent core-shell materials. The design and synthesis of P precursors for high-quality InP NQDs were conducted for the first time, and we were able to control the nucleation by varying the reactivity of P precursors, therefore achieving uniform large-sized InP NQDs. This opens the way for the large-scale production of high-quality Cd-free nanocrystal quantum dots. PMID:22289352

  6. Uniform field loop-gap resonator and rectangular TEU02 for aqueous sample EPR at 94 GHz

    Science.gov (United States)

    Sidabras, Jason W.; Sarna, Tadeusz; Mett, Richard R.; Hyde, James S.

    2017-09-01

    In this work we present the design and implementation of two uniform-field resonators: a seven-loop-six-gap loop-gap resonator (LGR) and a rectangular TEU02 cavity resonator. Each resonator has uniform-field-producing end-sections. These resonators have been designed for electron paramagnetic resonance (EPR) of aqueous samples at 94 GHz. The LGR geometry employs low-loss Rexolite end-sections to improve the field homogeneity over a 3 mm sample region-of-interest from near-cosine distribution to 90% uniform. The LGR was designed to accommodate large degassable Polytetrafluorethylen (PTFE) tubes (0.81 mm O.D.; 0.25 mm I.D.) for aqueous samples. Additionally, field modulation slots are designed for uniform 100 kHz field modulation incident at the sample. Experiments using a point sample of lithium phthalocyanine (LiPC) were performed to measure both the uniformity of the microwave magnetic field and 100 kHz field modulation, and confirm simulations. The rectangular TEU02 cavity resonator employs over-sized end-sections with sample shielding to provide an 87% uniform field for a 0.1 × 2 × 6 mm3 sample geometry. An evanescent slotted window was designed for light access to irradiate 90% of the sample volume. A novel dual-slot iris was used to minimize microwave magnetic field perturbations and maintain cross-sectional uniformity. Practical EPR experiments using the application of light irradiated rose bengal (4,5,6,7-tetrachloro-2‧,4‧,5‧,7‧-tetraiodofluorescein) were performed in the TEU02 cavity. The implementation of these geometries providing a practical designs for uniform field resonators that continue resonator advancements towards quantitative EPR spectroscopy.

  7. Methanol and ethanol vapor conversion in gas discharge with strongly non-uniform distribution of electric field on atmospheric pressure

    International Nuclear Information System (INIS)

    Golota, V.I.; Zavada, L.M.; Kotyukov, O.V.; Kudin, D.V.; Rodionov, S.V.; Pis'menetskoj, A.S.; Dotsenko, Yu.V.

    2010-01-01

    The barrierless gas discharge of negative polarity with strongly non-uniform distribution of electrical field in the methanol and ethanol vapour was studied. It is shown that level of methanol and ethanol conversion depended from power consumed by the discharge and exposition time for gas mixture in discharge zone. The condition for deep conversion of the methanol and ethanol vapours were determined. The water and carbon dioxide are the end products for the methanol and ethanol conversion. Formaldehyde and formic acid are the intermediates products in the conversion of methanol. And ethanol has a number of different compounds, including acetic acid, acetaldehyde, etc.

  8. Assessment indices for uniform and non-uniform thermal environments

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Different assessment indices for thermal environments were compared and selected for proper assessment of indoor thermal environments.30 subjects reported their overall thermal sensation,thermal comfort,and thermal acceptability in uniform and non-uniform conditions.The results show that these three assessment indices provide equivalent evaluations in uniform environments.However,overall thermal sensation differs from the other two indices and cannot be used as a proper index for the evaluation of non-uniform environments.The relationship between the percentage and the mean vote for each index is established.

  9. An analysis of the uniform core experiment

    Energy Technology Data Exchange (ETDEWEB)

    Waterson, R H

    1973-10-15

    This report describes an analysis of the Uniform Core of HITREX using the WIMS E codes, and presents the results of theory/experiment comparisons. The overall picture is one of good agreement for core reaction rate distributions, but theory umderestimating k{sub eff} by about 1.5% {delta}k/k.

  10. Can rare SAT formulae be easily recognized? On the efficiency of message-passing algorithms for K-SAT at large clause-to-variable ratios

    International Nuclear Information System (INIS)

    Altarelli, Fabrizio; Monasson, Remi; Zamponi, Francesco

    2007-01-01

    For large clause-to-variable ratios, typical K-SAT instances drawn from the uniform distribution have no solution. We argue, based on statistical mechanics calculations using the replica and cavity methods, that rare satisfiable instances from the uniform distribution are very similar to typical instances drawn from the so-called planted distribution, where instances are chosen uniformly between the ones that admit a given solution. It then follows, from a recent article by Feige, Mossel and Vilenchik (2006 Complete convergence of message passing algorithms for some satisfiability problems Proc. Random 2006 pp 339-50), that these rare instances can be easily recognized (in O(log N) time and with probability close to 1) by a simple message-passing algorithm

  11. Parallel processing and non-uniform grids in global air quality modeling

    NARCIS (Netherlands)

    Berkvens, P.J.F.; Bochev, Mikhail A.

    2002-01-01

    A large-scale global air quality model, running efficiently on a single vector processor, is enhanced to make more realistic and more long-term simulations feasible. Two strategies are combined: non-uniform grids and parallel processing. The communication through the hierarchy of non-uniform grids

  12. Aggregated Representation of Distribution Networks for Large-Scale Transmission Network Simulations

    DEFF Research Database (Denmark)

    Göksu, Ömer; Altin, Müfit; Sørensen, Poul Ejnar

    2014-01-01

    As a common practice of large-scale transmission network analysis the distribution networks have been represented as aggregated loads. However, with increasing share of distributed generation, especially wind and solar power, in the distribution networks, it became necessary to include...... the distributed generation within those analysis. In this paper a practical methodology to obtain aggregated behaviour of the distributed generation is proposed. The methodology, which is based on the use of the IEC standard wind turbine models, is applied on a benchmark distribution network via simulations....

  13. An empirical multivariate log-normal distribution representing uncertainty of biokinetic parameters for 137Cs

    International Nuclear Information System (INIS)

    Miller, G.; Martz, H.; Bertelli, L.; Melo, D.

    2008-01-01

    A simplified biokinetic model for 137 Cs has six parameters representing transfer of material to and from various compartments. Using a Bayesian analysis, the joint probability distribution of these six parameters is determined empirically for two cases with quite a lot of bioassay data. The distribution is found to be a multivariate log-normal. Correlations between different parameters are obtained. The method utilises a fairly large number of pre-determined forward biokinetic calculations, whose results are stored in interpolation tables. Four different methods to sample the multidimensional parameter space with a limited number of samples are investigated: random, stratified, Latin Hypercube sampling with a uniform distribution of parameters and importance sampling using a lognormal distribution that approximates the posterior distribution. The importance sampling method gives much smaller sampling uncertainty. No sampling method-dependent differences are perceptible for the uniform distribution methods. (authors)

  14. A Technical Approach on Large Data Distributed Over a Network

    Directory of Open Access Journals (Sweden)

    Suhasini G

    2011-12-01

    Full Text Available Data mining is nontrivial extraction of implicit, previously unknown and potential useful information from the data. For a database with number of records and for a set of classes such that each record belongs to one of the given classes, the problem of classification is to decide the class to which the given record belongs. The classification problem is also to generate a model for each class from given data set. We are going to make use of supervised classification in which we have training dataset of record, and for each record the class to which it belongs is known. There are many approaches to supervised classification. Decision tree is attractive in data mining environment as they represent rules. Rules can readily expressed in natural languages and they can be even mapped o database access languages. Now a days classification based on decision trees is one of the important problems in data mining   which has applications in many areas.  Now a days database system have become highly distributed, and we are using many paradigms. we consider the problem of inducing decision trees in a large distributed network of highly distributed databases. The classification based on decision tree can be done on the existence of distributed databases in healthcare and in bioinformatics, human computer interaction and by the view that these databases are soon to contain large amounts of data, characterized by its high dimensionality. Current decision tree algorithms would require high communication bandwidth, memory, and they are less efficient and scalability reduces when executed on such large volume of data. So there are some approaches being developed to improve the scalability and even approaches to analyse the data distributed over a network.[keywords: Data mining, Decision tree, decision tree induction, distributed data, classification

  15. Errors due to non-uniform distribution of fat in dual X-ray absorptiometry of the lumbar spine

    International Nuclear Information System (INIS)

    Tothill, P.; Pye, D.W.

    1992-01-01

    Errors in spinal dual X-ray absorptiometry (DXA) were studied by analysing X-ray CT scans taken for diagnostic purposes on 20 patients representing a wide range of fat content. The mean difference between the fat thickness over the vertebral bodies and that over a background area in antero-posterior (AP) scanning was 6.7 ± 8.1 mm for men and 13.4 ± 4.7 mm for women. For AP scanning a non-uniform fat distribution leads to a mean overestimate of 0.029 g/cm 2 for men and 0.057 g/cm 2 for women. The error exceeded 0.1 g/cm 2 in 10% of slices. For lateral scanning the error exceeded 0.1 g/cm 2 (about 15% of normal) in a quarter of slices. (author)

  16. Influence of ventilation structure on air flow distribution of large turbo-generator

    Science.gov (United States)

    Zhang, Liying; Ding, Shuye; Zhao, Zhijun; Yang, Jingmo

    2018-04-01

    For the 350 MW air - cooled turbo—generator, the rotor body is ventilated by sub -slots and 94 radial ventilation ducts and the end adopts arc segment and the straight section to acquire the wind. The stator is ventilated with five inlets and eight outlet air branches. In order to analyze the cooling effect of different ventilation schemes, a global physical model including the stator, rotor, casing and fan is established, and the assumptions and boundary conditions of the solution domain are given. the finite volume method is used to solve the problem, and the air flow distribution characteristics of each part of the motor under different ventilation schemes are obtained. The results show that the baffle at the end of the rotor can eliminate the eddy current at the end of the rotor, and make the flow distribution of cooling air more uniform and reasonable. The conclusions can provide reference for the design of motor ventilation structure.

  17. Non-uniform versus uniform attenuation correction in brain perfusion SPET of healthy volunteers

    International Nuclear Information System (INIS)

    Van Laere, K.; Versijpt, J.; Dierckx, R.; Koole, M.

    2001-01-01

    Although non-uniform attenuation correction (NUAC) can supply more accurate absolute quantification, it is not entirely clear whether NUAC provides clear-cut benefits in the routine clinical practice of brain SPET imaging. The aim of this study was to compare the effect of NUAC versus uniform attenuation correction (UAC) on volume of interest (VOI)-based semi-quantification of a large age- and gender-stratified brain perfusion normal database. Eighty-nine healthy volunteers (46 females and 43 males, aged 20-81 years) underwent standardised high-resolution single-photon emission tomography (SPET) with 925 MBq 99m Tc-ethyl cysteinate dimer (ECD) on a Toshiba GCA-9300A camera with 153 Gd or 99m Tc transmission CT scanning. Emission images were reconstructed by filtered back-projection and scatter corrected using the triple-energy window correction method. Both non-uniform Chang attenuation correction (one iteration) and uniform Sorenson correction (attenuation coefficient 0.09 cm -1 ) were applied. Images were automatically re-oriented to a stereotactic template on which 35 predefined VOIs were defined for semi-quantification (normalisation on total VOI counts). Small but significant differences between relative VOI uptake values for NUAC versus UAC in the infratentorial region were found. VOI standard deviations were significantly smaller for UAC, 4.5% (range 2.6-7.5), than for NUAC, 5.0% (2.3-9.0) (P 99m Tc-ECD uptake values in healthy volunteers to those obtained with NUAC, although values for the infratentorial region are slightly lower. NUAC produces a slight increase in inter-subject variability. Further study is necessary in various patient populations to establish the full clinical impact of NUAC in brain perfusion SPET. (orig.)

  18. Between giant oscillations and uniform distribution of droplets: The role of varying lumen of channels in microfluidic networks.

    Science.gov (United States)

    Cybulski, Olgierd; Jakiela, Slawomir; Garstecki, Piotr

    2015-12-01

    The simplest microfluidic network (a loop) comprises two parallel channels with a common inlet and a common outlet. Recent studies that assumed a constant cross section of the channels along their length have shown that the sequence of droplets entering the left (L) or right (R) arm of the loop can present either a uniform distribution of choices (e.g., RLRLRL...) or long sequences of repeated choices (RRR...LLL), with all the intermediate permutations being dynamically equivalent and virtually equally probable to be observed. We use experiments and computer simulations to show that even small variation of the cross section along channels completely shifts the dynamics either into the strong preference for highly grouped patterns (RRR...LLL) that generate system-size oscillations in flow or just the opposite-to patterns that distribute the droplets homogeneously between the arms of the loop. We also show the importance of noise in the process of self-organization of the spatiotemporal patterns of droplets. Our results provide guidelines for rational design of systems that reproducibly produce either grouped or homogeneous sequences of droplets flowing in microfluidic networks.

  19. Velocity Distributions in Inelastic Granular Gases with Continuous Size Distributions

    International Nuclear Information System (INIS)

    Li Rui; Li Zhi-Hao; Zhang Duan-Ming

    2011-01-01

    We study by numerical simulation the property of velocity distributions of granular gases with a power-law size distribution, driven by uniform heating and boundary heating. It is found that the form of velocity distribution is primarily controlled by the restitution coefficient η and q, the ratio between the average number of heatings and the average number of collisions in the system. Furthermore, we show that uniform and boundary heating can be understood as different limits of q, with q ≫ 1 and q ≤ 1, respectively. (general)

  20. Automated simultaneous assembly of multi-stage testing for the uniform CPA examination

    NARCIS (Netherlands)

    Breithaupt, Krista; Ariel, A.; Veldkamp, Bernard P.

    2004-01-01

    Some solutions used in the assembly of the computerized Uniform Certified Public Accountancy (CPA) licensing examination are offered as practical alternatives for operational programs producing large numbers of forms. The Uniform CPA examination will be offered as an adaptive multi-stage test (MST)

  1. ELECTRONIC CIRCUIT BOARDS NON-UNIFORM COOLING SYSTEM MODEL

    Directory of Open Access Journals (Sweden)

    D. V. Yevdulov

    2016-01-01

    Full Text Available Abstract. The paper considers a mathematical model of non-uniform cooling of electronic circuit boards. The block diagram of the system implementing this approach, the method of calculation of the electronic board temperature field, as well as the principle of its thermal performance optimizing are presented. In the considered scheme the main heat elimination from electronic board is produced by the radiator system, and additional cooling of the most temperature-sensitive components is produced by thermoelectric batteries. Are given the two-dimensional temperature fields of the electronic board during its uniform and non-uniform cooling, is carried out their comparison. As follows from the calculations results, when using a uniform overall cooling of electronic unit there is a waste of energy for the cooling 0f electronic board parts which temperature is within acceptable temperature range without the cooling system. This approach leads to the increase in the cooling capacity of used thermoelectric batteries in comparison with the desired values. This largely reduces the efficiency of heat elimination system. The use for electronic boards cooling of non-uniform local heat elimination removes this disadvantage. The obtained dependences show that in this case, the energy required to create a given temperature is smaller than when using a common uniform cooling. In this approach the temperature field of the electronic board is more uniform and the cooling is more efficient. 

  2. Spinal cord tolerance to single-session uniform irradiation in pigs: Implications for a dose-volume effect

    International Nuclear Information System (INIS)

    Medin, Paul M.; Foster, Ryan D.; Kogel, Albert J. van der; Sayre, James W.; McBride, William H.; Solberg, Timothy D.

    2013-01-01

    Background and purpose: This study was performed to test the hypothesis that spinal cord radiosensitivity is significantly modified by uniform versus laterally non-uniform dose distributions. Materials and methods: A uniform dose distribution was delivered to a 4.5–7.0 cm length of cervical spinal cord in 22 mature Yucatan minipigs for comparison with a companion study in which a laterally non-uniform dose was given [1]. Pigs were allocated into four dose groups with mean maximum spinal cord doses of 17.5 ± 0.1 Gy (n = 7), 19.5 ± 0.2 Gy (n = 6), 22.0 ± 0.1 Gy (n = 5), and 24.1 ± 0.2 Gy (n = 4). The study endpoint was motor neurologic deficit determined by a change in gait within one year. Spinal cord sections were stained with a Luxol fast blue/periodic acid Schiff combination. Results: Dose–response curves for uniform versus non-uniform spinal cord irradiation were nearly identical with ED 50 ’s (95% confidence interval) of 20.2 Gy (19.1–25.8) and 20.0 Gy (18.3–21.7), respectively. No neurologic change was observed for either dose distribution when the maximum spinal cord dose was ⩽17.8 Gy while all animals experienced deficits at doses ⩾21.8 Gy. Conclusion: No dose-volume effect was observed in pigs for the dose distributions studied and the endpoint of motor neurologic deficit; however, partial spinal cord irradiation resulted in less debilitating neurologic morbidity and histopathology

  3. Information Power Grid: Distributed High-Performance Computing and Large-Scale Data Management for Science and Engineering

    Science.gov (United States)

    Johnston, William E.; Gannon, Dennis; Nitzberg, Bill

    2000-01-01

    ) Coupling large-scale computing and data systems to scientific and engineering instruments (e.g., realtime interaction with experiments through real-time data analysis and interpretation presented to the experimentalist in ways that allow direct interaction with the experiment (instead of just with instrument control); (5) Highly interactive, augmented reality and virtual reality remote collaborations (e.g., Ames / Boeing Remote Help Desk providing field maintenance use of coupled video and NDI to a remote, on-line airframe structures expert who uses this data to index into detailed design databases, and returns 3D internal aircraft geometry to the field); (5) Single computational problems too large for any single system (e.g. the rotocraft reference calculation). Grids also have the potential to provide pools of resources that could be called on in extraordinary / rapid response situations (such as disaster response) because they can provide common interfaces and access mechanisms, standardized management, and uniform user authentication and authorization, for large collections of distributed resources (whether or not they normally function in concert). IPG development and deployment is addressing requirements obtained by analyzing a number of different application areas, in particular from the NASA Aero-Space Technology Enterprise. This analysis has focussed primarily on two types of users: the scientist / design engineer whose primary interest is problem solving (e.g. determining wing aerodynamic characteristics in many different operating environments), and whose primary interface to IPG will be through various sorts of problem solving frameworks. The second type of user is the tool designer: the computational scientists who convert physics and mathematics into code that can simulate the physical world. These are the two primary users of IPG, and they have rather different requirements. The results of the analysis of the needs of these two types of users provides a

  4. Uniformly active phase loaded selective catalytic reduction catalysts (V_2O_5/TNTs) with superior alkaline resistance performance

    International Nuclear Information System (INIS)

    Wang, Haiqiang; Wang, Penglu; Chen, Xiongbo; Wu, Zhongbiao

    2017-01-01

    Highlights: • VOSO_4 exhibited better synergistic effect with titanate nanotubes than NH_4VO_3. • Ion-exchange reaction occurs between VOSO_4 and titanate nanotubes. • Ion-exchange resulting in uniformly vanadium distribution on titanate nanotubes. • VOSO_4-based catalyst exhibited impressive SCR activity and alkaline resistance. - Abstract: In this work, protonated titanate nanotubes was performed as a potential useful support and different vanadium precursors (NH_4VO_3 and VOSO_4) were used to synthesize deNO_x catalysts. The results showed that VOSO_4 exhibited better synergistic effect with titanate nanotubes than NH_4VO_3, which was caused by the ion-exchange reaction. Then high loading content of vanadium, uniformly active phase distribution, better dispersion of vanadium, more acid sites, better V"5"+/V"4"+ redox cycles and superior oxygen mobility were achieved. Besides, VOSO_4-based titanate nanotubes catalysts also showed enhanced alkaline resistance than particles (P25) based catalysts. It was strongly associated with its abundant acid sites, large surface area, flexible redox cycles and oxygen transfer ability. For the loading on protonated titanate nanotubes, active metal with cation groups was better precursors than anion ones. V_2O_5/TNTs catalyst was a promising substitute for the commercial vanadium catalysts and the work conducted herein provided a useful idea to design uniformly active phase loaded catalyst.

  5. Fiber optic based optical tomography sensor for monitoring plasma uniformity

    International Nuclear Information System (INIS)

    Benck, Eric C.; Etemadi, Kasra

    2001-01-01

    A new type of fiber optic based optical tomography sensor has been developed for in situ monitoring of plasma uniformity. Optical tomography inverts optical emission measurements into the actual plasma distribution without assuming radial symmetry. The new sensor is designed to operate with only two small windows and acquire the necessary data in less than a second. Optical tomography is being tested on an ICP-GEC RF plasma source. Variations in plasma uniformity are measured as a function of different plasma conditions

  6. Performance of intraclass correlation coefficient (ICC) as a reliability index under various distributions in scale reliability studies.

    Science.gov (United States)

    Mehta, Shraddha; Bastero-Caballero, Rowena F; Sun, Yijun; Zhu, Ray; Murphy, Diane K; Hardas, Bhushan; Koch, Gary

    2018-04-29

    Many published scale validation studies determine inter-rater reliability using the intra-class correlation coefficient (ICC). However, the use of this statistic must consider its advantages, limitations, and applicability. This paper evaluates how interaction of subject distribution, sample size, and levels of rater disagreement affects ICC and provides an approach for obtaining relevant ICC estimates under suboptimal conditions. Simulation results suggest that for a fixed number of subjects, ICC from the convex distribution is smaller than ICC for the uniform distribution, which in turn is smaller than ICC for the concave distribution. The variance component estimates also show that the dissimilarity of ICC among distributions is attributed to the study design (ie, distribution of subjects) component of subject variability and not the scale quality component of rater error variability. The dependency of ICC on the distribution of subjects makes it difficult to compare results across reliability studies. Hence, it is proposed that reliability studies should be designed using a uniform distribution of subjects because of the standardization it provides for representing objective disagreement. In the absence of uniform distribution, a sampling method is proposed to reduce the non-uniformity. In addition, as expected, high levels of disagreement result in low ICC, and when the type of distribution is fixed, any increase in the number of subjects beyond a moderately large specification such as n = 80 does not have a major impact on ICC. Copyright © 2018 John Wiley & Sons, Ltd.

  7. Design of Availability-Dependent Distributed Services in Large-Scale Uncooperative Settings

    Science.gov (United States)

    Morales, Ramses Victor

    2009-01-01

    Thesis Statement: "Availability-dependent global predicates can be efficiently and scalably realized for a class of distributed services, in spite of specific selfish and colluding behaviors, using local and decentralized protocols". Several types of large-scale distributed systems spanning the Internet have to deal with availability variations…

  8. Heat transfer and friction characteristics of rotor-assembled strand heat exchanger studied by uniform design experiment

    Directory of Open Access Journals (Sweden)

    Yan Wei

    2015-10-01

    Full Text Available The uniform distribution and experimental design is employed to study the thermo-hydraulic characteristics of a heat exchanger, which consists of the rotor-assembled strands mounted in circular smooth tubes. The uniform distribution and experimental design parameters include multiple rotor parameters such as rotor diameters, rotor lead, and height of blade, with the aim of studying their influence on the PEC, that is, ( ( Nu z / Nu g / ( f g / f z 1 / 3 , which stands for the heat transfer and friction characteristics. The best matching schemes of rotor-assembled strand, which significantly improves PEC to 2.01, are given by the regression analysis of uniform distribution and experimental design table. The single-factor experiments are performed to compare a tube installed with different kinds of rotor-assembled strands with a smooth tube without any strands when the Reynolds number changes between 20,000 and 60,000. The experimental result is in good agreement with the result obtained by the regression analysis of uniform distribution and experimental design. It is shown that the rotor diameters play important role in the heat transfer, and the optimal PEC value is obtained under the case that the rotor diameter is 21 mm. The rotor lead also contributes to the improvement of heat transfer and its optimal value is 700 mm in this study. The Nusselt number, friction factor and PEC increase with the increase in blade height. It shows that the uniform distribution and experimental design is an efficient method to find out the optimal parameters.

  9. Facile synthesis of concentrated gold nanoparticles with low size-distribution in water: temperature and pH controls

    Directory of Open Access Journals (Sweden)

    Li Chunfang

    2011-01-01

    Full Text Available Abstract The citrate reduction method for the synthesis of gold nanoparticles (GNPs has known advantages but usually provides the products with low nanoparticle concentration and limits its application. Herein, we report a facile method to synthesize GNPs from concentrated chloroauric acid (2.5 mM via adding sodium hydroxide and controlling the temperature. It was found that adding a proper amount of sodium hydroxide can produce uniform concentrated GNPs with low size distribution; otherwise, the largely distributed nanoparticles or instable colloids were obtained. The low reaction temperature is helpful to control the nanoparticle formation rate, and uniform GNPs can be obtained in presence of optimized NaOH concentrations. The pH values of the obtained uniform GNPs were found to be very near to neutral, and the pH influence on the particle size distribution may reveal the different formation mechanism of GNPs at high or low pH condition. Moreover, this modified synthesis method can save more than 90% energy in the heating step. Such environmental-friendly synthesis method for gold nanoparticles may have a great potential in large-scale manufacturing for commercial and industrial demand.

  10. Facile synthesis of concentrated gold nanoparticles with low size-distribution in water: temperature and pH controls

    Science.gov (United States)

    Li, Chunfang; Li, Dongxiang; Wan, Gangqiang; Xu, Jie; Hou, Wanguo

    2011-07-01

    The citrate reduction method for the synthesis of gold nanoparticles (GNPs) has known advantages but usually provides the products with low nanoparticle concentration and limits its application. Herein, we report a facile method to synthesize GNPs from concentrated chloroauric acid (2.5 mM) via adding sodium hydroxide and controlling the temperature. It was found that adding a proper amount of sodium hydroxide can produce uniform concentrated GNPs with low size distribution; otherwise, the largely distributed nanoparticles or instable colloids were obtained. The low reaction temperature is helpful to control the nanoparticle formation rate, and uniform GNPs can be obtained in presence of optimized NaOH concentrations. The pH values of the obtained uniform GNPs were found to be very near to neutral, and the pH influence on the particle size distribution may reveal the different formation mechanism of GNPs at high or low pH condition. Moreover, this modified synthesis method can save more than 90% energy in the heating step. Such environmental-friendly synthesis method for gold nanoparticles may have a great potential in large-scale manufacturing for commercial and industrial demand.

  11. Cooling water distribution system

    Science.gov (United States)

    Orr, Richard

    1994-01-01

    A passive containment cooling system for a nuclear reactor containment vessel. Disclosed is a cooling water distribution system for introducing cooling water by gravity uniformly over the outer surface of a steel containment vessel using an interconnected series of radial guide elements, a plurality of circumferential collector elements and collector boxes to collect and feed the cooling water into distribution channels extending along the curved surface of the steel containment vessel. The cooling water is uniformly distributed over the curved surface by a plurality of weirs in the distribution channels.

  12. Below-threshold harmonic generation from strong non-uniform fields

    Science.gov (United States)

    Yavuz, I.

    2017-10-01

    Strong-field photoemission below the ionization threshold is a rich/complex region where atomic emission and harmonic generation may coexist. We studied the mechanism of below-threshold harmonics (BTH) from spatially non-uniform local fields near the metallic nanostructures. Discrete harmonics are generated due to the broken inversion symmetry, suggesting enriched coherent emission in the vuv frequency range. Through the numerical solution of the time-dependent Schrödinger equation, we investigate wavelength and intensity dependence of BTH. Wavelength dependence identifies counter-regular resonances; individual contributions from the multi-photon emission and channel-closing effects due to quantum path interferences. In order to understand the underlying mechanism of BTH, we devised a generalized semi-classical model, including the influence of Coulomb and non-uniform field interactions. As in uniform fields, Coulomb potential in non-uniform fields is the determinant of BTH; we observed that the generation of BTH are due to returning trajectories with negative energies. Due to large distance effectiveness of the non-uniformity, only long trajectories are noticeably affected.

  13. The mean distance to the nth neighbour in a uniform distribution of random points: an application of probability theory

    International Nuclear Information System (INIS)

    Bhattacharyya, Pratip; Chakrabarti, Bikas K

    2008-01-01

    We study different ways of determining the mean distance (r n ) between a reference point and its nth neighbour among random points distributed with uniform density in a D-dimensional Euclidean space. First, we present a heuristic method; though this method provides only a crude mathematical result, it shows a simple way of estimating (r n ). Next, we describe two alternative means of deriving the exact expression of (r n ): we review the method using absolute probability and develop an alternative method using conditional probability. Finally, we obtain an approximation to (r n ) from the mean volume between the reference point and its nth neighbour and compare it with the heuristic and exact results

  14. Uniformity testing: assessment of a centralized web-based uniformity analysis system.

    Science.gov (United States)

    Klempa, Meaghan C

    2011-06-01

    Uniformity testing is performed daily to ensure adequate camera performance before clinical use. The aim of this study is to assess the reliability of Beth Israel Deaconess Medical Center's locally built, centralized, Web-based uniformity analysis system by examining the differences between manufacturer and Web-based National Electrical Manufacturers Association integral uniformity calculations measured in the useful field of view (FOV) and the central FOV. Manufacturer and Web-based integral uniformity calculations measured in the useful FOV and the central FOV were recorded over a 30-d period for 4 cameras from 3 different manufacturers. These data were then statistically analyzed. The differences between the uniformity calculations were computed, in addition to the means and the SDs of these differences for each head of each camera. There was a correlation between the manufacturer and Web-based integral uniformity calculations in the useful FOV and the central FOV over the 30-d period. The average differences between the manufacturer and Web-based useful FOV calculations ranged from -0.30 to 0.099, with SD ranging from 0.092 to 0.32. For the central FOV calculations, the average differences ranged from -0.163 to 0.055, with SD ranging from 0.074 to 0.24. Most of the uniformity calculations computed by this centralized Web-based uniformity analysis system are comparable to the manufacturers' calculations, suggesting that this system is reasonably reliable and effective. This finding is important because centralized Web-based uniformity analysis systems are advantageous in that they test camera performance in the same manner regardless of the manufacturer.

  15. Pattern optimization of compound optical film for uniformity improvement in liquid-crystal displays

    Science.gov (United States)

    Huang, Bing-Le; Lin, Jin-tang; Ye, Yun; Xu, Sheng; Chen, En-guo; Guo, Tai-Liang

    2017-12-01

    The density dynamic adjustment algorithm (DDAA) is designed to efficiently promote the uniformity of the integrated backlight module (IBLM) by adjusting the microstructures' distribution on the compound optical film (COF), in which the COF is constructed in the SolidWorks and simulated in the TracePro. In order to demonstrate the universality of the proposed algorithm, the initial distribution is allocated by the Bezier curve instead of an empirical value. Simulation results maintains that the uniformity of the IBLM reaches over 90% only after four rounds. Moreover, the vertical and horizontal full width at half maximum of angular intensity are collimated to 24 deg and 14 deg, respectively. Compared with the current industry requirement, the IBLM has an 85% higher luminance uniformity of the emerging light, which demonstrate the feasibility and universality of the proposed algorithm.

  16. A Web-based Distributed Voluntary Computing Platform for Large Scale Hydrological Computations

    Science.gov (United States)

    Demir, I.; Agliamzanov, R.

    2014-12-01

    Distributed volunteer computing can enable researchers and scientist to form large parallel computing environments to utilize the computing power of the millions of computers on the Internet, and use them towards running large scale environmental simulations and models to serve the common good of local communities and the world. Recent developments in web technologies and standards allow client-side scripting languages to run at speeds close to native application, and utilize the power of Graphics Processing Units (GPU). Using a client-side scripting language like JavaScript, we have developed an open distributed computing framework that makes it easy for researchers to write their own hydrologic models, and run them on volunteer computers. Users will easily enable their websites for visitors to volunteer sharing their computer resources to contribute running advanced hydrological models and simulations. Using a web-based system allows users to start volunteering their computational resources within seconds without installing any software. The framework distributes the model simulation to thousands of nodes in small spatial and computational sizes. A relational database system is utilized for managing data connections and queue management for the distributed computing nodes. In this paper, we present a web-based distributed volunteer computing platform to enable large scale hydrological simulations and model runs in an open and integrated environment.

  17. Mandatory School Uniforms.

    Science.gov (United States)

    Cohn, Carl A.

    1996-01-01

    Shortly after implementing a mandatory school uniform policy, the Long Beach (California) Public Schools can boast 99% compliance and a substantial reduction in school crime. The uniforms can't be confused with gang colors, save parents money, and help identify outsiders. A sidebar lists ingredients for a mandatory uniform policy. (MLH)

  18. High-Rate Field Demonstration of Large-Alphabet Quantum Key Distribution

    Science.gov (United States)

    2016-10-12

    count rate of Bob’s detectors. In this detector-limited regime , it is advantageous to increase M to encode as much information as possible in each...High- rate field demonstration of large-alphabet quantum key distribution Catherine Lee,1, 2 Darius Bunandar,1 Zheshen Zhang,1 Gregory R. Steinbrecher...October 12, 2016) 2 Quantum key distribution (QKD) enables secure symmetric key exchange for information-theoretically secure com- munication via one-time

  19. Uniform risk functionals for characterization of strong earthquake ground motions

    International Nuclear Information System (INIS)

    Anderson, J.G.; Trifunac, M.D.

    1978-01-01

    A uniform risk functional (e.g., Fourier spectrum, response spectrum, duration, etc.) is defined so that the probability that it is exceeded by some earthquake during a selected period of time is independent of the frequency of seismic waves. Such a functional is derived by an independent calculation, at each frequency, for the probability that the quantity being considered will be exceeded. Different aspects of the seismicity can control the amplitude of a uniform risk functional in different frequency ranges, and a uniform risk functional does not necessarily describe the strong shaking from any single earthquake. To be useful for calculating uniform risk functionals, a scaling relationship must provide an independent estimate of amplitudes of the functional in several frequency bands. The scaling relationship of Trifunac (1976) for Fourier spectra satisfies this requirement and further describes the distribution of spectral amplitudes about the mean trend; here, it is applied to find uniform risk Fourier amplitude spectra. In an application to finding the uniform risk spectra at a realistic site, this method is quite sensitive to the description of seismicity. Distinct models of seismicity, all consistent with our current level of knowledge of an area, can give significantly different risk estimates

  20. Sealable stagnation flow geometries for the uniform deposition of materials and heat

    Science.gov (United States)

    McCarty, Kevin F.; Kee, Robert J.; Lutz, Andrew E.; Meeks, Ellen

    2001-01-01

    The present invention employs a constrained stagnation flow geometry apparatus to achieve the uniform deposition of materials or heat. The present invention maximizes uniform fluxes of reactant gases to flat surfaces while minimizing the use of reagents and finite dimension edge effects. This results, among other things, in large area continuous films that are uniform in thickness, composition and structure which is important in chemical vapor deposition processes such as would be used for the fabrication of semiconductors.

  1. School Uniforms Redux.

    Science.gov (United States)

    Dowling-Sendor, Benjamin

    2002-01-01

    Reviews a recent decision in "Littlefield" by the 5th Circuit upholding a school uniform policy. Advises board member who wish to adopt a school uniform policy to solicit input from parents and students, research the experiences of other school districts with uniform policies, and articulate the interests they wish to promote through uniform…

  2. X-ray radiographic technique for measuring density uniformity of silica aerogel

    International Nuclear Information System (INIS)

    Tabata, Makoto; Hatakeyama, Yoshikiyo; Adachi, Ichiro; Morita, Takeshi; Nishikawa, Keiko

    2013-01-01

    This paper proposes a new X-ray radiographic technique for measuring density uniformity of silica aerogels used as radiator in proximity-focusing ring-imaging Cherenkov detectors. To obtain high performance in a large-area detector, a key characteristic of radiator is the density (i.e. refractive index) uniformity of an individual aerogel monolith. At a refractive index of n=1.05, our requirement for the refractive index uniformity in the transverse plane direction of an aerogel tile is |δ(n−1)/(n−1)|<4% in a focusing dual layer radiator (with different refractive indices) scheme. We applied the radiographic technique to evaluate the density uniformity of our original aerogels from a trial production and that of Panasonic products (SP-50) as a reference, and to confirm they have sufficient density uniformity within ±1% along the transverse plane direction. The measurement results show that the proposed technique can quantitatively estimate the density uniformity of aerogels.

  3. Dynamics of leaching a uniformly fissured ore body

    International Nuclear Information System (INIS)

    Ignatov, A.A.; Proskurin, S.A.

    1987-01-01

    Mathematical simulation was used to study the dynamics of mass transfer during the percolation of a reagent solution through a packing of coarse ore particles. The uniformly fissured ore body was represented by a cubic packing of spherical particles of constant radius, formed from a chemically inert silicate cement with a uniformly distributed soluble mineral component. The rate of percolation of the reagent through the packing was constant. The proposed model can be used to find the conditions for underground hydrodynamic leaching. The rate of non-catalytic solid-liquid reaction was deduced on the basis of both the kinetics of dissolution of the mineral component of the ore and the rate of diffusion of the dissolved substance

  4. MARVIN: Distributed reasoning over large-scale Semantic Web data

    NARCIS (Netherlands)

    Oren, E.; Kotoulas, S.; Anadiotis, G.; Siebes, R.M.; ten Teije, A.C.M.; van Harmelen, F.A.H.

    2009-01-01

    Many Semantic Web problems are difficult to solve through common divide-and-conquer strategies, since they are hard to partition. We present Marvin, a parallel and distributed platform for processing large amounts of RDF data, on a network of loosely coupled peers. We present our divide-conquer-swap

  5. Effects of gas-flow structures on radical and etch-product density distributions on wafers in magnetomicrowave plasma etching reactors

    International Nuclear Information System (INIS)

    Ikegawa, Masato; Kobayashi, Jun'ichi; Fukuyama, Ryoji

    2001-01-01

    To achieve high etch rate, uniformity, good selectivity, and etch profile control across large diameter wafers, the distributions of ions, radicals, and etch products in magnetomicrowave high-etch-rate plasma etching reactors must be accurately controlled. In this work the effects of chamber heights, a focus ring around the wafer, and gas supply structures (or gas flow structures) on the radicals and etch products flux distribution onto the wafer were examined using the direct simulation Monte Carlo method and used to determine the optimal reactor geometry. The pressure uniformity on the wafer was less than ±1% when the chamber height was taller than 60 mm. The focus ring around the wafer produced uniform radical and etch-product fluxes but increased the etch-product flux on the wafer. A downward-flow gas-supply structure (type II) produced a more uniform radical distribution than that produced by a radial gas-supply structure (type I). The impact flow of the type II structure removed etch products from the wafer effectively and produced a uniform etch-product distribution even without the focus ring. Thus the downward-flow gas-supply structure (type II) was adopted in the design for the second-generation of a magnetomicrowave plasma etching reactor with a higher etching rate

  6. Estimation of current density distribution under electrodes for external defibrillation

    Directory of Open Access Journals (Sweden)

    Papazov Sava P

    2002-12-01

    Full Text Available Abstract Background Transthoracic defibrillation is the most common life-saving technique for the restoration of the heart rhythm of cardiac arrest victims. The procedure requires adequate application of large electrodes on the patient chest, to ensure low-resistance electrical contact. The current density distribution under the electrodes is non-uniform, leading to muscle contraction and pain, or risks of burning. The recent introduction of automatic external defibrillators and even wearable defibrillators, presents new demanding requirements for the structure of electrodes. Method and Results Using the pseudo-elliptic differential equation of Laplace type with appropriate boundary conditions and applying finite element method modeling, electrodes of various shapes and structure were studied. The non-uniformity of the current density distribution was shown to be moderately improved by adding a low resistivity layer between the metal and tissue and by a ring around the electrode perimeter. The inclusion of openings in long-term wearable electrodes additionally disturbs the current density profile. However, a number of small-size perforations may result in acceptable current density distribution. Conclusion The current density distribution non-uniformity of circular electrodes is about 30% less than that of square-shaped electrodes. The use of an interface layer of intermediate resistivity, comparable to that of the underlying tissues, and a high-resistivity perimeter ring, can further improve the distribution. The inclusion of skin aeration openings disturbs the current paths, but an appropriate selection of number and size provides a reasonable compromise.

  7. Alternative methods for evaluation of non-uniformity in nuclear medicine images

    International Nuclear Information System (INIS)

    Rasaneh, S.; Rajabi, H.; Hajizadeh, E.

    2005-01-01

    Non-uniformity test is the most essential in daily quality control procedures of nuclear medicine equipment's. However, the calculation of non-uniformity is hindered due to high level of noise in nuclear medicine data. Non-uniformity may be considered as a type of systematic error while noise is certainly a random error. The present methods of uniformity evaluation are not able to distinguish between systematic and random error and therefore produce incorrect results when noise is significant. In the present study, two hypothetical methods have been tested for evaluation of non-uniformity in nuclear medicine images. Materials and Methods: Using the Monte Carlo method, uniform and non-uniform flood images of different matrix sizes and different counts were generated. The uniformity of the images was calculated using the conventional method and proposed methods. The results were compared with the known non-uniformity data of simulated images. Results: It was observed that the value of integral uniformity never went below the recommended values except in small matrix size of high counts (more than 80 millions counts). The differential uniformity was quite insensitive to the degree of non-uniformity in large matrix size. Matrix size of 64*64 was only found to be suitable for the calculation of differential uniformity. It was observed that in uniform images, a small amount of non-uniformity changes the p-value of Kolmogorov-Smirnov test and noise amplitude of fast fourier transformation test significantly while the conventional methods failed to detect the nonuniformity. Conclusion: The conventional methods do not distinguish noise, which is always present in the data and occasional non-uniformity at low count density. In a uniform intact flood image, the difference between maximum and minimum pixel count (the value of integral uniformity) is much more than the recommended values for non-uniformity. After filtration of image, this difference decreases, but remains high

  8. Thermal freeze-out and longitudinally non-uniform collective expansion flow in relativistic heavy ion collisions

    CERN Document Server

    Feng Sheng Qin; LianShouLiu

    2002-01-01

    The non-uniform longitudinal flow model (NUFM) proposed recently is extended to include also the transverse flow. The resulting longitudinally non-uniform collective expansion model (NUCEM) is applied to the calculation of rapidity distribution of kaons, lambdas and protons in relativistic heavy ion collisions at CERN-SPS energies. The model results are compared with the 200 A GeV/c S-S and 158 A GeV/c Pb-Pb collision data. The central dips observed in experiments are reproduced in a natural way. It is found that the depth of the central dip depends on the magnitude of the parameter e and the mass of produced particles, i.e. the non-uniformity of the longitudinal flow which is described by the parameter e determines the depth of the central dip for produced particles. Comparing with one-dimensional non-uniform longitudinal flow model, the rapidity distribution of lighter strange particle kaon also shows a dip due to the effect of transverse flow

  9. The analysis of colour uniformity for a volumetric display based on a rotating LED array

    International Nuclear Information System (INIS)

    Wu, Jiang; Liu, Xu; Yan, Caijie; Xia, XinXing; Li, Haifeng

    2011-01-01

    There is a colour nonuniformity zone existing in three-dimensional (3D) volumetric displays which is based on the rotating colour light-emitting diode (LED) array. We analyse the reason for the colour nonuniformity zone by measuring the light intensity distribution and chromaticity coordinates of the LED in the volumetric display. Two boundaries of the colour nonuniformity zone are calculated. We measure the colour uniformities for a single cuboid of 3*3*4 voxels to display red, green, blue and white colour in different horizontal viewing angles, and for 64 cuboids distributed in the whole cylindrical image space with a fixed viewpoint. To evaluate the colour uniformity of a 3D image, we propose three evaluation indices of colour uniformity: the average of colour difference, the maximum colour difference and the variance of colour difference. The measurement results show that the character of colour uniformity is different for the 3D volumetric display and the two-dimensional display

  10. Mapping the distribution of the denitrifier community at large scales (Invited)

    Science.gov (United States)

    Philippot, L.; Bru, D.; Ramette, A.; Dequiedt, S.; Ranjard, L.; Jolivet, C.; Arrouays, D.

    2010-12-01

    Little information is available regarding the landscape-scale distribution of microbial communities and its environmental determinants. Here we combined molecular approaches and geostatistical modeling to explore spatial patterns of the denitrifying community at large scales. The distribution of denitrifrying community was investigated over 107 sites in Burgundy, a 31 500 km2 region of France, using a 16 X 16 km sampling grid. At each sampling site, the abundances of denitrifiers and 42 soil physico-chemical properties were measured. The relative contributions of land use, spatial distance, climatic conditions, time and soil physico-chemical properties to the denitrifier spatial distribution were analyzed by canonical variation partitioning. Our results indicate that 43% to 85% of the spatial variation in community abundances could be explained by the measured environmental parameters, with soil chemical properties (mostly pH) being the main driver. We found spatial autocorrelation up to 740 km and used geostatistical modelling to generate predictive maps of the distribution of denitrifiers at the landscape scale. Studying the distribution of the denitrifiers at large scale can help closing the artificial gap between the investigation of microbial processes and microbial community ecology, therefore facilitating our understanding of the relationships between the ecology of denitrifiers and N-fluxes by denitrification.

  11. High-voltage electrode optimization towards uniform surface treatment by a pulsed volume discharge

    International Nuclear Information System (INIS)

    Ponomarev, A V; Pedos, M S; Scherbinin, S V; Mamontov, Y I; Ponomarev, S V

    2015-01-01

    In this study, the shape and material of the high-voltage electrode of an atmospheric pressure plasma generation system were optimised. The research was performed with the goal of achieving maximum uniformity of plasma treatment of the surface of the low-voltage electrode with a diameter of 100 mm. In order to generate low-temperature plasma with the volume of roughly 1 cubic decimetre, a pulsed volume discharge was used initiated with a corona discharge. The uniformity of the plasma in the region of the low-voltage electrode was assessed using a system for measuring the distribution of discharge current density. The system's low-voltage electrode - collector - was a disc of 100 mm in diameter, the conducting surface of which was divided into 64 radially located segments of equal surface area. The current at each segment was registered by a high-speed measuring system controlled by an ARM™-based 32-bit microcontroller. To facilitate the interpretation of results obtained, a computer program was developed to visualise the results. The program provides a 3D image of the current density distribution on the surface of the low-voltage electrode. Based on the results obtained an optimum shape for a high-voltage electrode was determined. Uniformity of the distribution of discharge current density in relation to distance between electrodes was studied. It was proven that the level of non-uniformity of current density distribution depends on the size of the gap between electrodes. Experiments indicated that it is advantageous to use graphite felt VGN-6 (Russian abbreviation) as the material of the high-voltage electrode's emitting surface. (paper)

  12. A universal algorithm to generate pseudo-random numbers based on uniform mapping as homeomorphism

    International Nuclear Information System (INIS)

    Fu-Lai, Wang

    2010-01-01

    A specific uniform map is constructed as a homeomorphism mapping chaotic time series into [0,1] to obtain sequences of standard uniform distribution. With the uniform map, a chaotic orbit and a sequence orbit obtained are topologically equivalent to each other so the map can preserve the most dynamic properties of chaotic systems such as permutation entropy. Based on the uniform map, a universal algorithm to generate pseudo random numbers is proposed and the pseudo random series is tested to follow the standard 0–1 random distribution both theoretically and experimentally. The algorithm is not complex, which does not impose high requirement on computer hard ware and thus computation speed is fast. The method not only extends the parameter spaces but also avoids the drawback of small function space caused by constraints on chaotic maps used to generate pseudo random numbers. The algorithm can be applied to any chaotic system and can produce pseudo random sequence of high quality, thus can be a good universal pseudo random number generator. (general)

  13. A universal algorithm to generate pseudo-random numbers based on uniform mapping as homeomorphism

    Science.gov (United States)

    Wang, Fu-Lai

    2010-09-01

    A specific uniform map is constructed as a homeomorphism mapping chaotic time series into [0,1] to obtain sequences of standard uniform distribution. With the uniform map, a chaotic orbit and a sequence orbit obtained are topologically equivalent to each other so the map can preserve the most dynamic properties of chaotic systems such as permutation entropy. Based on the uniform map, a universal algorithm to generate pseudo random numbers is proposed and the pseudo random series is tested to follow the standard 0-1 random distribution both theoretically and experimentally. The algorithm is not complex, which does not impose high requirement on computer hard ware and thus computation speed is fast. The method not only extends the parameter spaces but also avoids the drawback of small function space caused by constraints on chaotic maps used to generate pseudo random numbers. The algorithm can be applied to any chaotic system and can produce pseudo random sequence of high quality, thus can be a good universal pseudo random number generator.

  14. A Multi-Resolution Spatial Model for Large Datasets Based on the Skew-t Distribution

    KAUST Repository

    Tagle, Felipe

    2017-12-06

    Large, non-Gaussian spatial datasets pose a considerable modeling challenge as the dependence structure implied by the model needs to be captured at different scales, while retaining feasible inference. Skew-normal and skew-t distributions have only recently begun to appear in the spatial statistics literature, without much consideration, however, for the ability to capture dependence at multiple resolutions, and simultaneously achieve feasible inference for increasingly large data sets. This article presents the first multi-resolution spatial model inspired by the skew-t distribution, where a large-scale effect follows a multivariate normal distribution and the fine-scale effects follow a multivariate skew-normal distributions. The resulting marginal distribution for each region is skew-t, thereby allowing for greater flexibility in capturing skewness and heavy tails characterizing many environmental datasets. Likelihood-based inference is performed using a Monte Carlo EM algorithm. The model is applied as a stochastic generator of daily wind speeds over Saudi Arabia.

  15. Activation rate uniformity in a bilateral IVNAA facility for two anthropomorphic phantoms

    Directory of Open Access Journals (Sweden)

    Miri Hakimabad Hashem

    2010-01-01

    Full Text Available Activation rate uniformity is the first property which is considered in the design of a prompt γ-ray in vivo neutron activation analysis facility. Preliminary studies on the activation rate distribution in the body can be done by use of Monte Carlo codes, such as the MCNP. In this paper, different bilateral configurations of an IVNAA system are considered in order to improve the activation rate uniformity in a water phantom measuring 32 cm x 100 cm x 16 cm. In the best case, uniformity parameters are U = 1.003 and R = 1.67, with the mean activation rate of 1.85×10-6 cm-3. In more accurate calculations, the water phantom is replaced by a body model. The model in question is a 5 year-old ORNL phantom filled with just soft tissue. For uniformity studies, the internal organs are not simulated. Finally, uniformity parameters in this case are U = 1.005 and R = 12.2.

  16. Uniform laser ablative acceleration of targets at 1014 W/cm2

    International Nuclear Information System (INIS)

    Obenschain, S.P.; Whitlock, R.R.; McLean, E.A.; Ripin, B.H.; Price, R.H.; Phillion, D.W.; Campbell, E.M.; Rosen, M.D.

    1982-01-01

    We present the first detailed investigations of the ablative acceleration of planar targets while simultaneously using high irradiance (10 14 W/cm 2 ), large focal diameters (1 mm) and long laser pulse duration (3 nsec). Included are measurements of target preheat, ablation pressures and uniformity achieved under these conditions. Targets were accelerated to high velocities with velocity profile uniformity approaching that required for high gain pellet implosions

  17. Uniform deposition of size-selected clusters using Lissajous scanning

    International Nuclear Information System (INIS)

    Beniya, Atsushi; Watanabe, Yoshihide; Hirata, Hirohito

    2016-01-01

    Size-selected clusters can be deposited on the surface using size-selected cluster ion beams. However, because of the cross-sectional intensity distribution of the ion beam, it is difficult to define the coverage of the deposited clusters. The aggregation probability of the cluster depends on coverage, whereas cluster size on the surface depends on the position, despite the size-selected clusters are deposited. It is crucial, therefore, to deposit clusters uniformly on the surface. In this study, size-selected clusters were deposited uniformly on surfaces by scanning the cluster ions in the form of Lissajous pattern. Two sets of deflector electrodes set in orthogonal directions were placed in front of the sample surface. Triangular waves were applied to the electrodes with an irrational frequency ratio to ensure that the ion trajectory filled the sample surface. The advantages of this method are simplicity and low cost of setup compared with raster scanning method. The authors further investigated CO adsorption on size-selected Pt n (n = 7, 15, 20) clusters uniformly deposited on the Al 2 O 3 /NiAl(110) surface and demonstrated the importance of uniform deposition.

  18. Uniform deposition of size-selected clusters using Lissajous scanning

    Energy Technology Data Exchange (ETDEWEB)

    Beniya, Atsushi; Watanabe, Yoshihide, E-mail: e0827@mosk.tytlabs.co.jp [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Hirata, Hirohito [Toyota Motor Corporation, 1200 Mishuku, Susono, Shizuoka 410-1193 (Japan)

    2016-05-15

    Size-selected clusters can be deposited on the surface using size-selected cluster ion beams. However, because of the cross-sectional intensity distribution of the ion beam, it is difficult to define the coverage of the deposited clusters. The aggregation probability of the cluster depends on coverage, whereas cluster size on the surface depends on the position, despite the size-selected clusters are deposited. It is crucial, therefore, to deposit clusters uniformly on the surface. In this study, size-selected clusters were deposited uniformly on surfaces by scanning the cluster ions in the form of Lissajous pattern. Two sets of deflector electrodes set in orthogonal directions were placed in front of the sample surface. Triangular waves were applied to the electrodes with an irrational frequency ratio to ensure that the ion trajectory filled the sample surface. The advantages of this method are simplicity and low cost of setup compared with raster scanning method. The authors further investigated CO adsorption on size-selected Pt{sub n} (n = 7, 15, 20) clusters uniformly deposited on the Al{sub 2}O{sub 3}/NiAl(110) surface and demonstrated the importance of uniform deposition.

  19. Effect of scandia doping method on the emission uniformity of scandate cathode with Sc2O3–W matrix

    International Nuclear Information System (INIS)

    Wang, Jinshu; Lai, Chen; Liu, Wei; Yang, Fan; Zhang, Xizhu; Cui, Yuntao; Zhou, Meiling

    2013-01-01

    Graphical abstract: Emission uniformity of the cathodes prepared by mechanical mixing (a) and spray drying method (b). - Highlights: • The emission uniformity of scandate cathodes has been quantitively obtained. • The nanoparticles on the cathode surface lead to the electric field enhancement. • The cathode prepared by spray drying method exhibits good emission uniformity. - Abstract: Scandia doped tungsten matrix dispenser cathodes were manufactured using scandia doped tungsten powder prepared by mechanical mixing, liquid–solid doping and a spray drying method. It is found the macrostructure of the cathode depended on the powder preparation method. The cathode prepared using the powder prepared by spray drying method had a homogenous and porous matrix characterized with grains with a diameter of less than 1 μm and with many nanoparticles distributing uniformly around these grains. The cathode with submicron structure and uniform distribution of scandia exhibited good emission uniformity. The emission uniformity ΔJ/J of the cathode prepared by spray drying method was 0.17, about 6 times lower than that of the cathode prepared by mechanical mixing method. The calculation results showed that the nanoparticles led to electric field enhancement. A Ba–Sc–O multilayer on the cathode surface and nanoparticles distributing mainly on W grains contributed to the emission property of the cathode

  20. Uniform magnetic targeting of magnetic particles attracted by a new ferromagnetic biological patch.

    Science.gov (United States)

    Pei, Ning; Cai, Lanlan; Yang, Kai; Ma, Jiaqi; Gong, Yongyong; Wang, Qixin; Huang, Zheyong

    2018-02-01

    A new non-toxic ferromagnetic biological patch (MBP) was designed in this paper. The MBP consisted of two external layers that were made of transparent silicone, and an internal layer that was made of a mixture of pure iron powder and silicon rubber. Finite-element analysis showed that the local inhomogeneous magnetic field (MF) around the MBP was generated when MBP was placed in a uniform MF. The local MF near the MBP varied with the uniform MF and shape of the MBP. Therefore, not only could the accumulation of paramagnetic particles be adjusted by controlling the strength of the uniform MF, but also the distribution of the paramagnetic particles could be improved with the different shape of the MBP. The relationship of the accumulation of paramagnetic particles or cells, magnetic flux density, and fluid velocity were studied through in vitro experiments and theoretical considerations. The accumulation of paramagnetic particles first increased with increment in the magnetic flux density of the uniform MF. But when the magnetic flux density of the uniform MF exceeded a specific value, the magnetic flux density of the MBP reached saturation, causing the accumulation of paramagnetic particles to fall. In addition, the adsorption morphology of magnetic particles or cells could be improved and the uniform distribution of magnetic particles could be achieved by changing the shape of the MBP. Also, MBP may be used as a new implant to attract magnetic drug carrier particles in magnetic drug targeting. Bioelectromagnetics. 39:98-107, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  1. Statistical searches for microlensing events in large, non-uniformly sampled time-domain surveys: A test using palomar transient factory data

    Energy Technology Data Exchange (ETDEWEB)

    Price-Whelan, Adrian M.; Agüeros, Marcel A. [Department of Astronomy, Columbia University, 550 W 120th Street, New York, NY 10027 (United States); Fournier, Amanda P. [Department of Physics, Broida Hall, University of California, Santa Barbara, CA 93106 (United States); Street, Rachel [Las Cumbres Observatory Global Telescope Network, Inc., 6740 Cortona Drive, Suite 102, Santa Barbara, CA 93117 (United States); Ofek, Eran O. [Benoziyo Center for Astrophysics, Weizmann Institute of Science, 76100 Rehovot (Israel); Covey, Kevin R. [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Levitan, David; Sesar, Branimir [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Laher, Russ R.; Surace, Jason, E-mail: adrn@astro.columbia.edu [Spitzer Science Center, California Institute of Technology, Mail Stop 314-6, Pasadena, CA 91125 (United States)

    2014-01-20

    Many photometric time-domain surveys are driven by specific goals, such as searches for supernovae or transiting exoplanets, which set the cadence with which fields are re-imaged. In the case of the Palomar Transient Factory (PTF), several sub-surveys are conducted in parallel, leading to non-uniform sampling over its ∼20,000 deg{sup 2} footprint. While the median 7.26 deg{sup 2} PTF field has been imaged ∼40 times in the R band, ∼2300 deg{sup 2} have been observed >100 times. We use PTF data to study the trade off between searching for microlensing events in a survey whose footprint is much larger than that of typical microlensing searches, but with far-from-optimal time sampling. To examine the probability that microlensing events can be recovered in these data, we test statistics used on uniformly sampled data to identify variables and transients. We find that the von Neumann ratio performs best for identifying simulated microlensing events in our data. We develop a selection method using this statistic and apply it to data from fields with >10 R-band observations, 1.1 × 10{sup 9} light curves, uncovering three candidate microlensing events. We lack simultaneous, multi-color photometry to confirm these as microlensing events. However, their number is consistent with predictions for the event rate in the PTF footprint over the survey's three years of operations, as estimated from near-field microlensing models. This work can help constrain all-sky event rate predictions and tests microlensing signal recovery in large data sets, which will be useful to future time-domain surveys, such as that planned with the Large Synoptic Survey Telescope.

  2. The multi-layered ring under parabolic distribution of radial stresses combined with uniform internal and external pressure

    Directory of Open Access Journals (Sweden)

    Christos F. Markides

    2017-04-01

    Full Text Available A recently introduced solution for the stress- and displacement-fields, developed in a multi-layered circular ring, composed of a finite number of linearly elastic concentric layers, subjected to a parabolic distribution of ra-dial stresses, is here extended to encompass a more general loading scheme, closer to actual conditions. The loading scheme includes, besides the para¬-bolic radial stresses, a combination of uniform pressures acting along the outer- and inner- most boundaries of the layered ring. The analytic solution of the problem is achieved by adopting Savin’s pioneering approach for an infinite plate with a hole strengthened by rings. Taking advantage of the results provided by the ana¬lytic solution, a numerical model, simulating the configuration of a three-layered ring (quite commonly encountered in practic¬al applications is validated. The numerical model is then used for a parametric analysis enlightening some crucial aspects of the overall response of the ring.

  3. LED Uniform Illumination Using Double Linear Fresnel Lenses for Energy Saving

    Directory of Open Access Journals (Sweden)

    Ngoc Hai Vu

    2017-12-01

    Full Text Available We present a linear Fresnel lens design for light-emitting diode (LED uniform illumination applications. The LED source is an array of LEDs. An array of collimating lens is applied to collimate output from the LED array. Two linear Fresnel lenses are used to redistribute the collimated beam along two dimensions in the illumination area. Collimating lens and linear Fresnel lens surfaces are calculated by geometrical optics and nonimaging optics. The collimated beam output from the collimating lens array is divided into many fragments. Each fragment is refracted by a segment of Fresnel lens and distributed over the illumination area, so that the total beam can be distributed to the illumination target uniformly. The simulation results show that this design has a compact structure, high optical efficiency of 82% and good uniformity of 76.9%. Some consideration of the energy savings and optical performance are discussed by comparison with other typical light sources. The results show that our proposed LED lighting system can reduce energy consumption five-times in comparison to using a conventional fluorescent lamp. Our research is a strong candidate for low cost, energy savings for indoor and outdoor lighting applications.

  4. [Study of the influence of uniform transverse magnetic field on the dose distribution of high energy electron beam using Monte Carlo method].

    Science.gov (United States)

    You, Shihu; Xu, Yun; Wu, Zhangwen; Hou, Qing; Guo, Chengjun

    2014-12-01

    In the present work, Monte Carlo simulations were employed to study the characteristics of the dose distribution of high energy electron beam in the presence of uniform transverse magnetic field. The simulations carried out the transport processes of the 30 MeV electron beam in the homogeneous water phantom with different magnetic field. It was found that the dose distribution of the 30 MeV electron beam had changed significantly because of the magnetic field. The result showed that the range of the electron beam was decreased obviously and it formed a very high dose peak at the end of the range, and the ratio of maximum dose to the dose of the surface was greatly increased. The results of this study demonstrated that we could change the depth dose distribution of electron beam which is analogous to the heavy ion by modulating the energy of the electron and magnetic field. It means that using magnetic fields in conjunction with electron radiation therapy has great application prospect, but it also has brought new challenges for the research of dose algorithm.

  5. Continuous sampling from distributed streams

    DEFF Research Database (Denmark)

    Graham, Cormode; Muthukrishnan, S.; Yi, Ke

    2012-01-01

    A fundamental problem in data management is to draw and maintain a sample of a large data set, for approximate query answering, selectivity estimation, and query planning. With large, streaming data sets, this problem becomes particularly difficult when the data is shared across multiple distribu......A fundamental problem in data management is to draw and maintain a sample of a large data set, for approximate query answering, selectivity estimation, and query planning. With large, streaming data sets, this problem becomes particularly difficult when the data is shared across multiple...... distributed sites. The main challenge is to ensure that a sample is drawn uniformly across the union of the data while minimizing the communication needed to run the protocol on the evolving data. At the same time, it is also necessary to make the protocol lightweight, by keeping the space and time costs low...... for each participant. In this article, we present communication-efficient protocols for continuously maintaining a sample (both with and without replacement) from k distributed streams. These apply to the case when we want a sample from the full streams, and to the sliding window cases of only the W most...

  6. Temperature Distribution and Influence Mechanism on Large Reflector Antennas under Solar Radiation

    Science.gov (United States)

    Wang, C. S.; Yuan, S.; Liu, X.; Xu, Q.; Wang, M.; Zhu, M. B.; Chen, G. D.; Duan, Y. H.

    2017-10-01

    The solar impact on antenna must be lessened for the large reflector antenna operating at high frequencies to have great electromagnetic performances. Therefore, researching the temperature distribution and its influence on large reflector antenna is necessary. The variation of solar incidence angle is first calculated. Then the model is simulated by the I-DEAS software, with the temperature, thermal stress, and thermal distortion distribution through the day obtained. In view of the important influence of shadow on antenna structure, a newly proposed method makes a comprehensive description of the temperature distribution on the reflector and its influence through the day by dividing a day into three different periods. The sound discussions and beneficial summary serve as the scientific foundation for the engineers to compensate the thermal distortion and optimize the antenna structure.

  7. Electrothermal Simulation of Large-Area Semiconductor Devices

    Directory of Open Access Journals (Sweden)

    C Kirsch

    2017-06-01

    Full Text Available The lateral charge transport in thin-film semiconductor devices is affected by the sheet resistance of the various layers. This may lead to a non-uniform current distribution across a large-area device resulting in inhomogeneous luminance, for example, as observed in organic light-emitting diodes (Neyts et al., 2006. The resistive loss in electrical energy is converted into thermal energy via Joule heating, which results in a temperature increase inside the device. On the other hand, the charge transport properties of the device materials are also temperature-dependent, such that we are facing a two-way coupled electrothermal problem. It has been demonstrated that adding thermal effects to an electrical model significantly changes the results (Slawinski et al., 2011. We present a mathematical model for the steady-state distribution of the electric potential and of the temperature across one electrode of a large-area semiconductor device, as well as numerical solutions obtained using the finite element method.

  8. High-Performance Monitoring Architecture for Large-Scale Distributed Systems Using Event Filtering

    Science.gov (United States)

    Maly, K.

    1998-01-01

    Monitoring is an essential process to observe and improve the reliability and the performance of large-scale distributed (LSD) systems. In an LSD environment, a large number of events is generated by the system components during its execution or interaction with external objects (e.g. users or processes). Monitoring such events is necessary for observing the run-time behavior of LSD systems and providing status information required for debugging, tuning and managing such applications. However, correlated events are generated concurrently and could be distributed in various locations in the applications environment which complicates the management decisions process and thereby makes monitoring LSD systems an intricate task. We propose a scalable high-performance monitoring architecture for LSD systems to detect and classify interesting local and global events and disseminate the monitoring information to the corresponding end- points management applications such as debugging and reactive control tools to improve the application performance and reliability. A large volume of events may be generated due to the extensive demands of the monitoring applications and the high interaction of LSD systems. The monitoring architecture employs a high-performance event filtering mechanism to efficiently process the large volume of event traffic generated by LSD systems and minimize the intrusiveness of the monitoring process by reducing the event traffic flow in the system and distributing the monitoring computation. Our architecture also supports dynamic and flexible reconfiguration of the monitoring mechanism via its Instrumentation and subscription components. As a case study, we show how our monitoring architecture can be utilized to improve the reliability and the performance of the Interactive Remote Instruction (IRI) system which is a large-scale distributed system for collaborative distance learning. The filtering mechanism represents an Intrinsic component integrated

  9. Angular distribution of large qsub(T) muon pairs in different reference frames

    International Nuclear Information System (INIS)

    Lindfors, J.

    1979-01-01

    The angular distribution of large transverse momentum muon pairs produced in hadron-hadron collisions is calculated in lowest order of perturbative QCD. It is shown that for the process quark-antiquark → gluon + μ + μ - the polar and azimuthal angle distributions can be made independent of the parton distributions by choosing a special reference frame, the Collins-Soper frame, but for the process quark + gluon → quark + μ + μ - this is not possible. (author)

  10. Isotropic gates in large gamma detector arrays versus angular distributions

    International Nuclear Information System (INIS)

    Iacob, V.E.; Duchene, G.

    1997-01-01

    The quality of the angular distribution information extracted from high-fold gamma-gamma coincidence events is analyzed. It is shown that a correct quasi-isotropic gate setting, available at the modern large gamma-ray detector arrays, essentially preserves the quality of the angular information. (orig.)

  11. The ecology, distribution, conservation and management of large old trees.

    Science.gov (United States)

    Lindenmayer, David B; Laurance, William F

    2017-08-01

    Large old trees are some of the most iconic biota on earth and are integral parts of many terrestrial ecosystems including those in tropical, temperate and boreal forests, deserts, savannas, agro-ecological areas, and urban environments. In this review, we provide new insights into the ecology, function, evolution and management of large old trees through broad cross-disciplinary perspectives from literatures in plant physiology, growth and development, evolution, habitat value for fauna and flora, and conservation management. Our review reveals that the diameter, height and longevity of large old trees varies greatly on an inter-specific basis, thereby creating serious challenges in defining large old trees and demanding an ecosystem- and species-specific definition that will only rarely be readily transferable to other species or ecosystems. Such variation is also manifested by marked inter-specific differences in the key attributes of large old trees (beyond diameter and height) such as the extent of buttressing, canopy architecture, the extent of bark micro-environments and the prevalence of cavities. We found that large old trees play an extraordinary range of critical ecological roles including in hydrological regimes, nutrient cycles and numerous ecosystem processes. Large old trees strongly influence the spatial and temporal distribution and abundance of individuals of the same species and populations of numerous other plant and animal species. We suggest many key characteristics of large old trees such as extreme height, prolonged lifespans, and the presence of cavities - which confer competitive and evolutionary advantages in undisturbed environments - can render such trees highly susceptible to a range of human influences. Large old trees are vulnerable to threats ranging from droughts, fire, pests and pathogens, to logging, land clearing, landscape fragmentation and climate change. Tackling such diverse threats is challenging because they often

  12. Quasi-uniform Space

    OpenAIRE

    Coghetto Roland

    2016-01-01

    In this article, using mostly Pervin [9], Kunzi [6], [8], [7], Williams [11] and Bourbaki [3] works, we formalize in Mizar [2] the notions of quasiuniform space, semi-uniform space and locally uniform space.

  13. Large-Scale Ichthyoplankton and Water Mass Distribution along the South Brazil Shelf

    Science.gov (United States)

    de Macedo-Soares, Luis Carlos Pinto; Garcia, Carlos Alberto Eiras; Freire, Andrea Santarosa; Muelbert, José Henrique

    2014-01-01

    Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27′ and 34°51′S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients. PMID:24614798

  14. Large-scale ichthyoplankton and water mass distribution along the South Brazil Shelf.

    Directory of Open Access Journals (Sweden)

    Luis Carlos Pinto de Macedo-Soares

    Full Text Available Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27' and 34°51'S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients.

  15. Large-scale ichthyoplankton and water mass distribution along the South Brazil Shelf.

    Science.gov (United States)

    de Macedo-Soares, Luis Carlos Pinto; Garcia, Carlos Alberto Eiras; Freire, Andrea Santarosa; Muelbert, José Henrique

    2014-01-01

    Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27' and 34°51'S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients.

  16. Spatial model of the gecko foot hair: functional significance of highly specialized non-uniform geometry.

    Science.gov (United States)

    Filippov, Alexander E; Gorb, Stanislav N

    2015-02-06

    One of the important problems appearing in experimental realizations of artificial adhesives inspired by gecko foot hair is so-called clusterization. If an artificially produced structure is flexible enough to allow efficient contact with natural rough surfaces, after a few attachment-detachment cycles, the fibres of the structure tend to adhere one to another and form clusters. Normally, such clusters are much larger than original fibres and, because they are less flexible, form much worse adhesive contacts especially with the rough surfaces. Main problem here is that the forces responsible for the clusterization are the same intermolecular forces which attract fibres to fractal surface of the substrate. However, arrays of real gecko setae are much less susceptible to this problem. One of the possible reasons for this is that ends of the seta have more sophisticated non-uniformly distributed three-dimensional structure than that of existing artificial systems. In this paper, we simulated three-dimensional spatial geometry of non-uniformly distributed branches of nanofibres of the setal tip numerically, studied its attachment-detachment dynamics and discussed its advantages versus uniformly distributed geometry.

  17. On distributed wavefront reconstruction for large-scale adaptive optics systems.

    Science.gov (United States)

    de Visser, Cornelis C; Brunner, Elisabeth; Verhaegen, Michel

    2016-05-01

    The distributed-spline-based aberration reconstruction (D-SABRE) method is proposed for distributed wavefront reconstruction with applications to large-scale adaptive optics systems. D-SABRE decomposes the wavefront sensor domain into any number of partitions and solves a local wavefront reconstruction problem on each partition using multivariate splines. D-SABRE accuracy is within 1% of a global approach with a speedup that scales quadratically with the number of partitions. The D-SABRE is compared to the distributed cumulative reconstruction (CuRe-D) method in open-loop and closed-loop simulations using the YAO adaptive optics simulation tool. D-SABRE accuracy exceeds CuRe-D for low levels of decomposition, and D-SABRE proved to be more robust to variations in the loop gain.

  18. Calculation of the fuel temperature coefficient of reactivity considering non-uniform radial temperature distribution in the fuel rod

    Energy Technology Data Exchange (ETDEWEB)

    Pazirandeh, Ali [Islamic Azad Univ., Tehran (Iran, Islamic Republic of). Science and Research Branch; Hooshyar Mobaraki, Almas

    2017-07-15

    The safe operation of a reactor is based on feedback models. In this paper we attempted to discuss the influence of a non-uniform radial temperature distribution on the fuel rod temperature coefficient of reactivity. The paper demonstrates that the neutron properties of a reactor core is based on effective temperature of the fuel to obtain the correct fuel temperature feedback. The value of volume-averaged temperature being used in the calculations of neutron physics with feedbacks would result in underestimating the probable event. In the calculation it is necessary to use the effective temperature of the fuel in order to provide correct accounting of the fuel temperature feedback. Fuel temperature changes in different zones of the core and consequently reactivity coefficient change are an important parameter for analysis of transient conditions. The restricting factor that compensates the inserted reactivity is the temperature reactivity coefficient and effective delayed neutron fraction.

  19. Quasi-uniform Space

    Directory of Open Access Journals (Sweden)

    Coghetto Roland

    2016-09-01

    Full Text Available In this article, using mostly Pervin [9], Kunzi [6], [8], [7], Williams [11] and Bourbaki [3] works, we formalize in Mizar [2] the notions of quasiuniform space, semi-uniform space and locally uniform space.

  20. Do School Uniforms Fit?

    Science.gov (United States)

    White, Kerry A.

    2000-01-01

    In 1994, Long Beach (California) Unified School District began requiring uniforms in all elementary and middle schools. Now, half of all urban school systems and many suburban schools have uniform policies. Research on uniforms' effectiveness is mixed. Tightened dress codes may be just as effective and less litigious. (MLH)

  1. The spatial distribution of pollutants in pipe-scale of large-diameter pipelines in a drinking water distribution system

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jingqing [College of Engineering and Architecture, Zhejiang University, Hangzhou 310058 (China); Chen, Huanyu [College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Binhai Industrial Technology Research Institute of Zhejiang University, Tianjin 300000 (China); Yao, Lingdan; Wei, Zongyuan [College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Lou, Liping, E-mail: loulp@zju.edu.cn [College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Shan, Yonggui; Endalkachew, Sahle-Demessie; Mallikarjuna, Nadagouda [Environmental Protection Agency, Office of Research and Development, NRMRL, Cincinnati, OH 45220 (United States); Hu, Baolan [College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Zhou, Xiaoyan [Shaoxing Water Environmental Science Institute Co. Ltd, Zhejiang 312000 (China)

    2016-11-05

    Highlights: • First investigating the spatial distribution of pollutants in pipe-scale. • Spatial distribution of heavy metals indicated their sources were different. • Three main factors effete the distribution of pollutants. • Organic deposits mainly included microbial and microalgae metabolites. - Abstract: In large-diameter drinking water pipelines, spatial differences in hydraulic and physiochemical conditions may also result in spatial variations in pipe corrosion, biofilm growth and pollutant accumulation. In this article, the spatial distributions of various metals and organic contaminants in two 19-year-old grey cast iron pipes which had an internal diameter of 600 mm (DN600), were investigated and analyzed by Atomic Absorption Spectrometry, Gas Chromatography–Mass Spectrometry, Energy Dispersive Spectrometer, X-ray Diffraction, etc. The spatial distribution of heavy metals varied significantly across the pipe section, and iron, manganese, lead, copper, and chromium were highest in concentration in the upper portion pipe-scales. However, the highest aluminum and zinc content was detected in the lower portion pipe-scales. Apart from some common types of hydrocarbons formed by microbial metabolites, there were also some microalgae metabolites and exogenous contaminants accumulated in pipe-scale, which also exhibited high diversity between different spatial locations. The spatial distributions of the physical and chemical properties of pipe-scale and contaminants were quite different in large-diameter pipes. The finding put forward higher requirements on the research method about drinking water distribution system chemical safety. And the scientific community need understand trend and dynamics of drinking water pipe systems better.

  2. The spatial distribution of pollutants in pipe-scale of large-diameter pipelines in a drinking water distribution system

    International Nuclear Information System (INIS)

    Liu, Jingqing; Chen, Huanyu; Yao, Lingdan; Wei, Zongyuan; Lou, Liping; Shan, Yonggui; Endalkachew, Sahle-Demessie; Mallikarjuna, Nadagouda; Hu, Baolan; Zhou, Xiaoyan

    2016-01-01

    Highlights: • First investigating the spatial distribution of pollutants in pipe-scale. • Spatial distribution of heavy metals indicated their sources were different. • Three main factors effete the distribution of pollutants. • Organic deposits mainly included microbial and microalgae metabolites. - Abstract: In large-diameter drinking water pipelines, spatial differences in hydraulic and physiochemical conditions may also result in spatial variations in pipe corrosion, biofilm growth and pollutant accumulation. In this article, the spatial distributions of various metals and organic contaminants in two 19-year-old grey cast iron pipes which had an internal diameter of 600 mm (DN600), were investigated and analyzed by Atomic Absorption Spectrometry, Gas Chromatography–Mass Spectrometry, Energy Dispersive Spectrometer, X-ray Diffraction, etc. The spatial distribution of heavy metals varied significantly across the pipe section, and iron, manganese, lead, copper, and chromium were highest in concentration in the upper portion pipe-scales. However, the highest aluminum and zinc content was detected in the lower portion pipe-scales. Apart from some common types of hydrocarbons formed by microbial metabolites, there were also some microalgae metabolites and exogenous contaminants accumulated in pipe-scale, which also exhibited high diversity between different spatial locations. The spatial distributions of the physical and chemical properties of pipe-scale and contaminants were quite different in large-diameter pipes. The finding put forward higher requirements on the research method about drinking water distribution system chemical safety. And the scientific community need understand trend and dynamics of drinking water pipe systems better.

  3. Pinning down the large-x gluon with NNLO top-quark pair differential distributions

    Energy Technology Data Exchange (ETDEWEB)

    Czakon, Michał [Institut für Theoretische Teilchenphysik und Kosmologie, RWTH Aachen University,D-52056 Aachen (Germany); Hartland, Nathan P. [Department of Physics and Astronomy, VU University Amsterdam,De Boelelaan 1081, NL-1081, HV Amsterdam (Netherlands); Nikhef,Science Park 105, NL-1098 XG Amsterdam (Netherlands); Mitov, Alexander [Cavendish Laboratory, University of Cambridge,Cambridge CB3 0HE (United Kingdom); Nocera, Emanuele R. [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, OX1 3NP, Oxford (United Kingdom); Rojo, Juan [Department of Physics and Astronomy, VU University Amsterdam,De Boelelaan 1081, NL-1081, HV Amsterdam (Netherlands); Nikhef,Science Park 105, NL-1098 XG Amsterdam (Netherlands)

    2017-04-10

    Top-quark pair production at the LHC is directly sensitive to the gluon PDF at large x. While total cross-section data is already included in several PDF determinations, differential distributions are not, because the corresponding NNLO calculations have become available only recently. In this work we study the impact on the large-x gluon of top-quark pair differential distributions measured by ATLAS and CMS at √s=8 TeV. Our analysis, performed in the NNPDF3.0 framework at NNLO accuracy, allows us to identify the optimal combination of LHC top-quark pair measurements that maximize the constraints on the gluon, as well as to assess the compatibility between ATLAS and CMS data. We find that differential distributions from top-quark pair production provide significant constraints on the large-x gluon, comparable to those obtained from inclusive jet production data, and thus should become an important ingredient for the next generation of global PDF fits.

  4. Pinning down the large-x gluon with NNLO top-quark pair differential distributions

    International Nuclear Information System (INIS)

    Czakon, Michał; Hartland, Nathan P.; Mitov, Alexander; Nocera, Emanuele R.; Rojo, Juan

    2017-01-01

    Top-quark pair production at the LHC is directly sensitive to the gluon PDF at large x. While total cross-section data is already included in several PDF determinations, differential distributions are not, because the corresponding NNLO calculations have become available only recently. In this work we study the impact on the large-x gluon of top-quark pair differential distributions measured by ATLAS and CMS at √s=8 TeV. Our analysis, performed in the NNPDF3.0 framework at NNLO accuracy, allows us to identify the optimal combination of LHC top-quark pair measurements that maximize the constraints on the gluon, as well as to assess the compatibility between ATLAS and CMS data. We find that differential distributions from top-quark pair production provide significant constraints on the large-x gluon, comparable to those obtained from inclusive jet production data, and thus should become an important ingredient for the next generation of global PDF fits.

  5. Inviscid evolution of large amplitude filaments in a uniform gravity field

    Energy Technology Data Exchange (ETDEWEB)

    Angus, J. R. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Krasheninnikov, S. I. [University of California, San Diego, La Jolla, California 92093 (United States); National Research Nuclear University “MEPhl” Kashirskoe sh., 31, 115563 Moscow (Russian Federation)

    2014-11-15

    The inviscid evolution of localized density stratifications under the influence of a uniform gravity field in a homogeneous, ambient background is studied. The fluid is assumed to be incompressible, and the stratification, or filament, is assumed to be initially isotropic and at rest. It is shown that the center of mass energy can be related to the center of mass position in a form analogous to that of a solid object in a gravity field g by introducing an effective gravity field g{sub eff}, which is less than g due to energy that goes into the background and into non-center of mass motion of the filament. During the early stages of the evolution, g{sub eff} is constant in time and can be determined from the solution of a 1D differential equation that depends on the initial, radially varying density profile of the filament. For small amplitude filaments such that ρ{sub 0} ≪ 1, where ρ{sub 0} is the relative amplitude of the filament to the background, the early stage g{sub eff} scales linearly with ρ{sub 0}, but as ρ{sub 0}→∞, g{sub eff}→g and is thus independent of ρ{sub 0}. Fully nonlinear simulations are performed for the evolution of Gaussian filaments, and it is found that the time t{sub max}, which is defined as the time for the center of mass velocity to reach its maximum value U{sub max}, occurs very soon after the constant acceleration phase and so U{sub max}≈g{sub eff}(t=0)t{sub max}. The simulation results show that U{sub max}∼1/t{sub max}∼√(ρ{sub 0}) for ρ{sub 0} ≪ 1, in agreement with theory and results from previous authors, but that U{sub max} and t{sub max} both scale approximately with √(ρ{sub 0}) for ρ{sub 0} ≫ 1. The fact that U{sub max} and t{sub max} have the same scaling with ρ{sub 0} for large amplitude filaments is in agreement with the theory presented in this paper.

  6. Passive containment cooling water distribution device

    Science.gov (United States)

    Conway, Lawrence E.; Fanto, Susan V.

    1994-01-01

    A passive containment cooling system for a nuclear reactor containment vessel. Disclosed is a cooling water distribution system for introducing cooling water by gravity uniformly over the outer surface of a steel containment vessel using a series of radial guide elements and cascading weir boxes to collect and then distribute the cooling water into a series of distribution areas through a plurality of cascading weirs. The cooling water is then uniformly distributed over the curved surface by a plurality of weir notches in the face plate of the weir box.

  7. Large Survey Database: A Distributed Framework for Storage and Analysis of Large Datasets

    Science.gov (United States)

    Juric, Mario

    2011-01-01

    The Large Survey Database (LSD) is a Python framework and DBMS for distributed storage, cross-matching and querying of large survey catalogs (>10^9 rows, >1 TB). The primary driver behind its development is the analysis of Pan-STARRS PS1 data. It is specifically optimized for fast queries and parallel sweeps of positionally and temporally indexed datasets. It transparently scales to more than >10^2 nodes, and can be made to function in "shared nothing" architectures. An LSD database consists of a set of vertically and horizontally partitioned tables, physically stored as compressed HDF5 files. Vertically, we partition the tables into groups of related columns ('column groups'), storing together logically related data (e.g., astrometry, photometry). Horizontally, the tables are partitioned into partially overlapping ``cells'' by position in space (lon, lat) and time (t). This organization allows for fast lookups based on spatial and temporal coordinates, as well as data and task distribution. The design was inspired by the success of Google BigTable (Chang et al., 2006). Our programming model is a pipelined extension of MapReduce (Dean and Ghemawat, 2004). An SQL-like query language is used to access data. For complex tasks, map-reduce ``kernels'' that operate on query results on a per-cell basis can be written, with the framework taking care of scheduling and execution. The combination leverages users' familiarity with SQL, while offering a fully distributed computing environment. LSD adds little overhead compared to direct Python file I/O. In tests, we sweeped through 1.1 Grows of PanSTARRS+SDSS data (220GB) less than 15 minutes on a dual CPU machine. In a cluster environment, we achieved bandwidths of 17Gbits/sec (I/O limited). Based on current experience, we believe LSD should scale to be useful for analysis and storage of LSST-scale datasets. It can be downloaded from http://mwscience.net/lsd.

  8. Polarized Uniform Linear Array System: Beam Radiation Pattern, Beamforming Diversity Order, and Channel Capacity

    Directory of Open Access Journals (Sweden)

    Xin Su

    2015-01-01

    Full Text Available There have been many studies regarding antenna polarization; however, there have been few publications on the analysis of the channel capacity for polarized antenna systems using the beamforming technique. According to Chung et al., the channel capacity is determined by the density of scatterers and the transmission power, which is obtained based on the assumption that scatterers are uniformly distributed on a 3D spherical scattering model. However, it contradicts the practical scenario, where scatterers may not be uniformly distributed under outdoor environment, and lacks the consideration of fading channel gain. In this study, we derive the channel capacity of polarized uniform linear array (PULA systems using the beamforming technique in a practical scattering environment. The results show that, for PULA systems, the channel capacity, which is boosted by beamforming diversity, can be determined using the channel gain, beam radiation pattern, and beamforming diversity order (BDO, where the BDO is dependent on the antenna characteristics and array configurations.

  9. Improvement of Pulping Uniformity by Measurement of Single Fiber Kappa Number

    Energy Technology Data Exchange (ETDEWEB)

    Richard R. Gustafson; James B. Callis

    2001-11-20

    A method to measure the kappa of single fibers by staining with a fluorescent dye, Acridine Orange (AO), has been developed. This method is now applied to develop and automated flow-through instrument that permits routine kappa analysis on thousands of images of AO stained fibers to give the fiber kappa number distribution of a pulp sample in a few minutes. The design and operation of the instrument are similar to that of a flow cytometer but with the addition of extensive fiber imaging capability. Fluorescence measurements in the flow-through instrument are found to be consistent with those made with fluorescence microscope provided the signal processing in the flow-thou instrument is handled propertly. The kappa distributions of pulps that were analyzed by means of a density gradient column are compared to those measured with the flow-through instrument with good results. The kappa distributions of various laboratory pulps and commercial pulps have been measured. It has been found that all pulps are non-uniform but that ommercial pulps generally have broader kappa distributions thatn their laboratory counterparts. The effects of different pulping methods and chip pretreatments on pulp uniformity are discussed in the report. Finally, the application of flow-through fluorescence technology to other single fiber measurements are presented.

  10. Liquid jets injected into non-uniform crossflow

    Science.gov (United States)

    Tambe, Samir

    An experimental study has been conducted with liquid jets injected transversely into a crossflow to study the effect of non-uniformities in the crossflow velocity distribution to the jet behavior. Two different non-uniform crossflows were created during this work, a shear-laden crossflow and a swirling crossflow. The shear-laden crossflow was generated by merging two independent, co-directional, parallel airstreams creating a shear mixing layer at the interface between them. The crossflow exhibited a quasi-linear velocity gradient across the height of the test chamber. By varying the velocities of the two airstreams, the sense and the slope of the crossflow velocity gradient could be changed. Particle Image Velocimetry (PIV) studies were conducted to characterize the crossflow. The parameter, UR, is defined as the ratio of the velocities of the two streams and governs the velocity gradient. A positive velocity gradient was observed for UR > 1 and a negative velocity gradient for UR Phase Doppler Particle Anemometry (PDPA) studies were conducted to study the penetration and atomization of 0.5 mm diameter water jets injected into this crossflow. The crossflow velocity gradient was observed to have a significant effect on jet penetration as well as the post breakup spray. For high UR (> 1), jet penetration increased and the Sauter Mean Diameter (SMD) distribution became more uniform. For low UR (Doppler Velocimetry (LDV) was used to study the crossflow velocities. The axial (Ux) and the tangential (Utheta) components of the crossflow velocity were observed to decrease with increasing radial distance away from the centerbody. The flow angle of the crossflow was smaller than the vane exit angle, with the difference increasing with the vane exit angle. Water jets were injected from a 0.5 mm diameter orifice located on a cylindrical centerbody. Multi-plane PIV measurements were conducted to study the penetration and droplet velocity distribution of the jets. The jets were

  11. Uniformly active phase loaded selective catalytic reduction catalysts (V{sub 2}O{sub 5}/TNTs) with superior alkaline resistance performance

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haiqiang; Wang, Penglu [Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Environmental & Resources Science, Zhejiang University, 310058 Hangzhou (China); Zhejiang Provincial Engineering Research Center of Industrial Boiler & Furnace Flue Gas Pollution Control, Hangzhou 310027 (China); Chen, Xiongbo [South China Institute of Environmental Sciences, Ministry of Environmental Protection, Guangzhou 510655 (China); Wu, Zhongbiao, E-mail: zbwu@zju.edu.cn [Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Environmental & Resources Science, Zhejiang University, 310058 Hangzhou (China); Zhejiang Provincial Engineering Research Center of Industrial Boiler & Furnace Flue Gas Pollution Control, Hangzhou 310027 (China)

    2017-02-15

    Highlights: • VOSO{sub 4} exhibited better synergistic effect with titanate nanotubes than NH{sub 4}VO{sub 3}. • Ion-exchange reaction occurs between VOSO{sub 4} and titanate nanotubes. • Ion-exchange resulting in uniformly vanadium distribution on titanate nanotubes. • VOSO{sub 4}-based catalyst exhibited impressive SCR activity and alkaline resistance. - Abstract: In this work, protonated titanate nanotubes was performed as a potential useful support and different vanadium precursors (NH{sub 4}VO{sub 3} and VOSO{sub 4}) were used to synthesize deNO{sub x} catalysts. The results showed that VOSO{sub 4} exhibited better synergistic effect with titanate nanotubes than NH{sub 4}VO{sub 3}, which was caused by the ion-exchange reaction. Then high loading content of vanadium, uniformly active phase distribution, better dispersion of vanadium, more acid sites, better V{sup 5+}/V{sup 4+} redox cycles and superior oxygen mobility were achieved. Besides, VOSO{sub 4}-based titanate nanotubes catalysts also showed enhanced alkaline resistance than particles (P25) based catalysts. It was strongly associated with its abundant acid sites, large surface area, flexible redox cycles and oxygen transfer ability. For the loading on protonated titanate nanotubes, active metal with cation groups was better precursors than anion ones. V{sub 2}O{sub 5}/TNTs catalyst was a promising substitute for the commercial vanadium catalysts and the work conducted herein provided a useful idea to design uniformly active phase loaded catalyst.

  12. Rigorous Results for the Distribution of Money on Connected Graphs

    Science.gov (United States)

    Lanchier, Nicolas; Reed, Stephanie

    2018-05-01

    This paper is concerned with general spatially explicit versions of three stochastic models for the dynamics of money that have been introduced and studied numerically by statistical physicists: the uniform reshuffling model, the immediate exchange model and the model with saving propensity. All three models consist of systems of economical agents that consecutively engage in pairwise monetary transactions. Computer simulations performed in the physics literature suggest that, when the number of agents and the average amount of money per agent are large, the limiting distribution of money as time goes to infinity approaches the exponential distribution for the first model, the gamma distribution with shape parameter two for the second model and a distribution similar but not exactly equal to a gamma distribution whose shape parameter depends on the saving propensity for the third model. The main objective of this paper is to give rigorous proofs of these conjectures and also extend these conjectures to generalizations of the first two models and a variant of the third model that include local rather than global interactions, i.e., instead of choosing the two interacting agents uniformly at random from the system, the agents are located on the vertex set of a general connected graph and can only interact with their neighbors.

  13. Effect of scandia doping method on the emission uniformity of scandate cathode with Sc{sub 2}O{sub 3}–W matrix

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jinshu, E-mail: wangjsh@bjut.edu.cn; Lai, Chen; Liu, Wei; Yang, Fan; Zhang, Xizhu; Cui, Yuntao; Zhou, Meiling

    2013-09-01

    Graphical abstract: Emission uniformity of the cathodes prepared by mechanical mixing (a) and spray drying method (b). - Highlights: • The emission uniformity of scandate cathodes has been quantitively obtained. • The nanoparticles on the cathode surface lead to the electric field enhancement. • The cathode prepared by spray drying method exhibits good emission uniformity. - Abstract: Scandia doped tungsten matrix dispenser cathodes were manufactured using scandia doped tungsten powder prepared by mechanical mixing, liquid–solid doping and a spray drying method. It is found the macrostructure of the cathode depended on the powder preparation method. The cathode prepared using the powder prepared by spray drying method had a homogenous and porous matrix characterized with grains with a diameter of less than 1 μm and with many nanoparticles distributing uniformly around these grains. The cathode with submicron structure and uniform distribution of scandia exhibited good emission uniformity. The emission uniformity ΔJ/J of the cathode prepared by spray drying method was 0.17, about 6 times lower than that of the cathode prepared by mechanical mixing method. The calculation results showed that the nanoparticles led to electric field enhancement. A Ba–Sc–O multilayer on the cathode surface and nanoparticles distributing mainly on W grains contributed to the emission property of the cathode.

  14. Games Uniforms Unveiled

    Institute of Scientific and Technical Information of China (English)

    Linda

    2008-01-01

    The uniforms for Beijing Olympics’ workers, technical staff and volunteers have been unveiled to mark the 200-day countdown to the Games. The uniforms feature the key element of the clouds of promise and will be in three colors:red for Beijing Olympic Games Committee staff, blue

  15. Impact of Tab Location on Large Format Lithium-Ion Pouch Cell Based on Fully Coupled Tree-Dimensional Electrochemical-Thermal Modeling

    International Nuclear Information System (INIS)

    Samba, Ahmadou; Omar, Noshin; Gualous, Hamid; Capron, Odile; Van den Bossche, Peter; Van Mierlo, Joeri

    2014-01-01

    This paper presents extensive three-dimensional (3D) simulations of large LiFPO 4 pouch cells. 3D simulations of the Li-ion battery behavior are highly nonlinear and computationally demanding. Coupling electrochemical modeling to thermal models represents an important step towards accurate simulation of the Li-ion battery. Non-uniform temperature, potential and current density through the battery induce non-uniform use of the active material and can have a negative impact on cell performance and lifetime. Different pouch cell designs, with different tab locations, have been investigated in term of performance, current density, potential and heat distributions. The model is first validated with experimental data at different current discharge rates. Afterwards, the electrochemical, thermal and electrical behaviors over each cell design under high discharge rate (4 I t ) are compared between configurations. It has been shown that the designs with symmetrical configurations show uniform potential and current density gradient, which minimize the ohmic heat and lead to more uniform active material utilization and temperature distributions across the cell surface.Introduction

  16. Highly ordered uniform single-crystal Bi nanowires: fabrication and characterization

    International Nuclear Information System (INIS)

    Bisrat, Y; Luo, Z P; Davis, D; Lagoudas, D

    2007-01-01

    A mechanical pressure injection technique has been used to fabricate uniform bismuth (Bi) nanowires in the pores of an anodic aluminum oxide (AAO) template. The AAO template was prepared from general purity aluminum by a two-step anodization followed by heat treatment to achieve highly ordered nanochannels. The nanowires were then fabricated by an injection technique whereby the molten Bi was injected into the AAO template using a hydraulic pressure method. The Bi nanowires prepared by this method were found to be dense and continuous with uniform diameter throughout the length. Electron diffraction experiments using the transmission electron microscope on cross-sectional and free-standing longitudinal Bi nanowires showed that the majority of the individual nanowires were single crystalline, with preferred orientation of growth along the [011] zone axis of the pseudo-cubic structure. The work presented here provides an inexpensive and effective way of fabricating highly ordered single-crystalline Bi nanowires, with uniform size distributions

  17. Effect of non-uniform current distribution on the stability in Nb-Ti cable-in-conduit superconducting conductor

    International Nuclear Information System (INIS)

    Wadayama, Y.; Koizumi, N.; Takahashi, Y.; Matsui, K.; Tsuji, H.; Shimamoto, S.

    1996-01-01

    30kA-NbTi Demo Poloidal Coil (DPC-U) exhibited instability such as the conductor quenches at 40% of the rated current which is still much smaller than the expected conductor critical current. It was found that this instability was caused by the non-uniform current distribution in the DPC-U conductor whose strands were insulated from each other. To investigate the instability of the DPC-U conductor, a stability experiment of a subsize conductor consisting of 27 strands was performed and the effect of the current imbalance on the stability was investigated. The current imbalance was forcibly established in the conductor using two current sources in this experiment. The experimental results indicate that the stability margin decreases as the current imbalance becomes larger and that the stability margin of the conductor is governed by the stability of the strand with the highest current in the conductor. Also, it is confirmed from the experimental results that the instability of DPC-U has to be attributed to the current imbalance in the conductor

  18. Analysis of single blow effectiveness in non-uniform parallel plate regenerators

    DEFF Research Database (Denmark)

    Jensen, Jesper Buch; Bahl, Christian Robert Haffenden; Engelbrecht, Kurt

    2011-01-01

    Non-uniform distributions of plate spacings in parallel plate regenerators have been found to induce loss of performance. In this paper, it has been investigated how variations of three geometric parameters (the aspect ratio, the porosity, and the standard deviation of the plate spacing) affects...

  19. Non-uniform distribution pattern for differentially expressed genes of transgenic rice Huahui 1 at different developmental stages and environments.

    Directory of Open Access Journals (Sweden)

    Zhi Liu

    Full Text Available DNA microarray analysis is an effective method to detect unintended effects by detecting differentially expressed genes (DEG in safety assessment of genetically modified (GM crops. With the aim to reveal the distribution of DEG of GM crops under different conditions, we performed DNA microarray analysis using transgenic rice Huahui 1 (HH1 and its non-transgenic parent Minghui 63 (MH63 at different developmental stages and environmental conditions. Considerable DEG were selected in each group of HH1 under different conditions. For each group of HH1, the number of DEG was different; however, considerable common DEG were shared between different groups of HH1. These findings suggested that both DEG and common DEG were adequate for investigation of unintended effects. Furthermore, a number of significantly changed pathways were found in all groups of HH1, indicating genetic modification caused everlasting changes to plants. To our knowledge, our study for the first time provided the non-uniformly distributed pattern for DEG of GM crops at different developmental stages and environments. Our result also suggested that DEG selected in GM plants at specific developmental stage and environment could act as useful clues for further evaluation of unintended effects of GM plants.

  20. Sampling large random knots in a confined space

    International Nuclear Information System (INIS)

    Arsuaga, J; Blackstone, T; Diao, Y; Hinson, K; Karadayi, E; Saito, M

    2007-01-01

    DNA knots formed under extreme conditions of condensation, as in bacteriophage P4, are difficult to analyze experimentally and theoretically. In this paper, we propose to use the uniform random polygon model as a supplementary method to the existing methods for generating random knots in confinement. The uniform random polygon model allows us to sample knots with large crossing numbers and also to generate large diagrammatically prime knot diagrams. We show numerically that uniform random polygons sample knots with large minimum crossing numbers and certain complicated knot invariants (as those observed experimentally). We do this in terms of the knot determinants or colorings. Our numerical results suggest that the average determinant of a uniform random polygon of n vertices grows faster than O(e n 2 )). We also investigate the complexity of prime knot diagrams. We show rigorously that the probability that a randomly selected 2D uniform random polygon of n vertices is almost diagrammatically prime goes to 1 as n goes to infinity. Furthermore, the average number of crossings in such a diagram is at the order of O(n 2 ). Therefore, the two-dimensional uniform random polygons offer an effective way in sampling large (prime) knots, which can be useful in various applications

  1. Sampling large random knots in a confined space

    Science.gov (United States)

    Arsuaga, J.; Blackstone, T.; Diao, Y.; Hinson, K.; Karadayi, E.; Saito, M.

    2007-09-01

    DNA knots formed under extreme conditions of condensation, as in bacteriophage P4, are difficult to analyze experimentally and theoretically. In this paper, we propose to use the uniform random polygon model as a supplementary method to the existing methods for generating random knots in confinement. The uniform random polygon model allows us to sample knots with large crossing numbers and also to generate large diagrammatically prime knot diagrams. We show numerically that uniform random polygons sample knots with large minimum crossing numbers and certain complicated knot invariants (as those observed experimentally). We do this in terms of the knot determinants or colorings. Our numerical results suggest that the average determinant of a uniform random polygon of n vertices grows faster than O(e^{n^2}) . We also investigate the complexity of prime knot diagrams. We show rigorously that the probability that a randomly selected 2D uniform random polygon of n vertices is almost diagrammatically prime goes to 1 as n goes to infinity. Furthermore, the average number of crossings in such a diagram is at the order of O(n2). Therefore, the two-dimensional uniform random polygons offer an effective way in sampling large (prime) knots, which can be useful in various applications.

  2. Sampling large random knots in a confined space

    Energy Technology Data Exchange (ETDEWEB)

    Arsuaga, J [Department of Mathematics, San Francisco State University, 1600 Holloway Ave, San Francisco, CA 94132 (United States); Blackstone, T [Department of Computer Science, San Francisco State University, 1600 Holloway Ave., San Francisco, CA 94132 (United States); Diao, Y [Department of Mathematics and Statistics, University of North Carolina at Charlotte, Charlotte, NC 28223 (United States); Hinson, K [Department of Mathematics and Statistics, University of North Carolina at Charlotte, Charlotte, NC 28223 (United States); Karadayi, E [Department of Mathematics, University of South Florida, 4202 E Fowler Avenue, Tampa, FL 33620 (United States); Saito, M [Department of Mathematics, University of South Florida, 4202 E Fowler Avenue, Tampa, FL 33620 (United States)

    2007-09-28

    DNA knots formed under extreme conditions of condensation, as in bacteriophage P4, are difficult to analyze experimentally and theoretically. In this paper, we propose to use the uniform random polygon model as a supplementary method to the existing methods for generating random knots in confinement. The uniform random polygon model allows us to sample knots with large crossing numbers and also to generate large diagrammatically prime knot diagrams. We show numerically that uniform random polygons sample knots with large minimum crossing numbers and certain complicated knot invariants (as those observed experimentally). We do this in terms of the knot determinants or colorings. Our numerical results suggest that the average determinant of a uniform random polygon of n vertices grows faster than O(e{sup n{sup 2}}). We also investigate the complexity of prime knot diagrams. We show rigorously that the probability that a randomly selected 2D uniform random polygon of n vertices is almost diagrammatically prime goes to 1 as n goes to infinity. Furthermore, the average number of crossings in such a diagram is at the order of O(n{sup 2}). Therefore, the two-dimensional uniform random polygons offer an effective way in sampling large (prime) knots, which can be useful in various applications.

  3. Self-* and Adaptive Mechanisms for Large Scale Distributed Systems

    Science.gov (United States)

    Fragopoulou, P.; Mastroianni, C.; Montero, R.; Andrjezak, A.; Kondo, D.

    Large-scale distributed computing systems and infrastructure, such as Grids, P2P systems and desktop Grid platforms, are decentralized, pervasive, and composed of a large number of autonomous entities. The complexity of these systems is such that human administration is nearly impossible and centralized or hierarchical control is highly inefficient. These systems need to run on highly dynamic environments, where content, network topologies and workloads are continuously changing. Moreover, they are characterized by the high degree of volatility of their components and the need to provide efficient service management and to handle efficiently large amounts of data. This paper describes some of the areas for which adaptation emerges as a key feature, namely, the management of computational Grids, the self-management of desktop Grid platforms and the monitoring and healing of complex applications. It also elaborates on the use of bio-inspired algorithms to achieve self-management. Related future trends and challenges are described.

  4. Tools for the Automation of Large Distributed Control Systems

    CERN Document Server

    Gaspar, Clara

    2005-01-01

    The new LHC experiments at CERN will have very large numbers of channels to operate. In order to be able to configure and monitor such large systems, a high degree of parallelism is necessary. The control system is built as a hierarchy of sub-systems distributed over several computers. A toolkit - SMI++, combining two approaches: finite state machines and rule-based programming, allows for the description of the various sub-systems as decentralized deciding entities, reacting is real-time to changes in the system, thus providing for the automation of standard procedures and for the automatic recovery from error conditions in a hierarchical fashion. In this paper we will describe the principles and features of SMI++ as well as its integration with an industrial SCADA tool for use by the LHC experiments and we will try to show that such tools, can provide a very convenient mechanism for the automation of large scale, high complexity, applications.

  5. A Directed Acyclic Graph-Large Margin Distribution Machine Model for Music Symbol Classification.

    Science.gov (United States)

    Wen, Cuihong; Zhang, Jing; Rebelo, Ana; Cheng, Fanyong

    2016-01-01

    Optical Music Recognition (OMR) has received increasing attention in recent years. In this paper, we propose a classifier based on a new method named Directed Acyclic Graph-Large margin Distribution Machine (DAG-LDM). The DAG-LDM is an improvement of the Large margin Distribution Machine (LDM), which is a binary classifier that optimizes the margin distribution by maximizing the margin mean and minimizing the margin variance simultaneously. We modify the LDM to the DAG-LDM to solve the multi-class music symbol classification problem. Tests are conducted on more than 10000 music symbol images, obtained from handwritten and printed images of music scores. The proposed method provides superior classification capability and achieves much higher classification accuracy than the state-of-the-art algorithms such as Support Vector Machines (SVMs) and Neural Networks (NNs).

  6. Fabrication of Slanted Cu Nanopillars with Uniform Arrays

    Directory of Open Access Journals (Sweden)

    Sung-Woon Cho

    2016-02-01

    Full Text Available Slanted Cu nanopillars with uniform arrays were fabricat‐ ed using slanted Si channel structures as templates. A slanted plasma etching technique was employed, utilizing a Faraday cage system for the formation of these slanted channel structures. The angle of the slanted channel structures was accurately controlled because ions entering the Faraday cage maintained their direction. After the slanted channel structures were formed, they were filled with Cu by electroless deposition. Chemical mechanical polishing was then used to remove the excess Cu film and the SiO2 masks. Finally, the remaining poly Si of the channel structures was removed by wet chemical etching. This work offers a novel method for the fabrication of slanted metal nanostructures with uniform arrays covering a large area.

  7. Secure File Allocation and Caching in Large-scale Distributed Systems

    DEFF Research Database (Denmark)

    Di Mauro, Alessio; Mei, Alessandro; Jajodia, Sushil

    2012-01-01

    In this paper, we present a file allocation and caching scheme that guarantees high assurance, availability, and load balancing in a large-scale distributed file system that can support dynamic updates of authorization policies. The scheme uses fragmentation and replication to store files with hi......-balancing, and reducing delay of read operations. The system offers a trade-off-between performance and security that is dynamically tunable according to the current level of threat. We validate our mechanisms with extensive simulations in an Internet-like network.......In this paper, we present a file allocation and caching scheme that guarantees high assurance, availability, and load balancing in a large-scale distributed file system that can support dynamic updates of authorization policies. The scheme uses fragmentation and replication to store files with high...... security requirements in a system composed of a majority of low-security servers. We develop mechanisms to fragment files, to allocate them into multiple servers, and to cache them as close as possible to their readers while preserving the security requirement of the files, providing load...

  8. Large-scale uniform ZnO tetrapods on catalyst free glass substrate by thermal evaporation method

    Energy Technology Data Exchange (ETDEWEB)

    Alsultany, Forat H., E-mail: foratusm@gmail.com [School of Physics, USM, 11800 Penang (Malaysia); Hassan, Z. [Institute of Nano-Optoelectronics Research and Technology Laboratory (INOR), USM, 11800 Penang (Malaysia); Ahmed, Naser M. [School of Physics, USM, 11800 Penang (Malaysia)

    2016-07-15

    Highlights: • Investigate the growth of ZnO-Ts on glass substrate by thermal evaporation method. • Glass substrate without any catalyst or a seed layer. • The morphology was controlled by adjusting the temperature of the material and the substrate. • Glass substrate was placed vertically in the quartz tube. - Abstract: Here, we report for the first time the catalyst-free growth of large-scale uniform shape and size ZnO tetrapods on a glass substrate via thermal evaporation method. Three-dimensional networks of ZnO tetrapods have needle–wire junctions, an average leg length of 2.1–2.6 μm, and a diameter of 35–240 nm. The morphology and structure of ZnO tetrapods were investigated by controlling the preparation temperature of each of the Zn powder and the glass substrate under O{sub 2} and Ar gases. Studies were carried out on ZnO tetrapods using X-ray diffraction, field emission scanning electron microscopy, UV–vis spectrophotometer, and a photoluminescence. The results showed that the sample grow in the hexagonal wurtzite structure with preferentially oriented along (002) direction, good crystallinity and high transmittance. The band gap value is about 3.27 eV. Photoluminescence spectrum exhibits a very sharp peak at 378 nm and a weak broad green emission.

  9. Assessment of uniformity and signal-to-noise ratio in radiological image intensifier TV systems

    International Nuclear Information System (INIS)

    Malone, J.F.; O'Connor, M.K.; Maher, K.P.

    1985-01-01

    A method of measuring the uniformity of radiological Image Intensifier-TV systems is described. Large non-uniformities were observed in the systems tested. A method of estimating the Signal-to-Noise Ratio in such systems is also presented and applied to characterise the effectiveness of the noise reduction techniques used in digital fluoroscopy. (author)

  10. Towards a uniform and large-scale deposition of MoS2 nanosheets via sulfurization of ultra-thin Mo-based solid films.

    Science.gov (United States)

    Vangelista, Silvia; Cinquanta, Eugenio; Martella, Christian; Alia, Mario; Longo, Massimo; Lamperti, Alessio; Mantovan, Roberto; Basset, Francesco Basso; Pezzoli, Fabio; Molle, Alessandro

    2016-04-29

    Large-scale integration of MoS2 in electronic devices requires the development of reliable and cost-effective deposition processes, leading to uniform MoS2 layers on a wafer scale. Here we report on the detailed study of the heterogeneous vapor-solid reaction between a pre-deposited molybdenum solid film and sulfur vapor, thus resulting in a controlled growth of MoS2 films onto SiO2/Si substrates with a tunable thickness and cm(2)-scale uniformity. Based on Raman spectroscopy and photoluminescence, we show that the degree of crystallinity in the MoS2 layers is dictated by the deposition temperature and thickness. In particular, the MoS2 structural disorder observed at low temperature (<750 °C) and low thickness (two layers) evolves to a more ordered crystalline structure at high temperature (1000 °C) and high thickness (four layers). From an atomic force microscopy investigation prior to and after sulfurization, this parametrical dependence is associated with the inherent granularity of the MoS2 nanosheet that is inherited by the pristine morphology of the pre-deposited Mo film. This work paves the way to a closer control of the synthesis of wafer-scale and atomically thin MoS2, potentially extendable to other transition metal dichalcogenides and hence targeting massive and high-volume production for electronic device manufacturing.

  11. Local, distributed topology control for large-scale wireless ad-hoc networks

    NARCIS (Netherlands)

    Nieberg, T.; Hurink, Johann L.

    In this document, topology control of a large-scale, wireless network by a distributed algorithm that uses only locally available information is presented. Topology control algorithms adjust the transmission power of wireless nodes to create a desired topology. The algorithm, named local power

  12. Magnetic fields and uniformity of radio frequency power deposition in low-frequency inductively coupled plasmas with crossed internal oscillating currents

    International Nuclear Information System (INIS)

    Tsakadze, E.L.; Ostrikov, K.; Tsakadze, Z.L.; Vladimirov, S.V.; Xu, S.

    2004-01-01

    Radial and axial distributions of magnetic fields in a low-frequency (∼460 kHz) inductively coupled plasma source with two internal crossed planar rf current sheets are reported. The internal antenna configuration comprises two orthogonal sets of eight alternately reconnected parallel and equidistant copper litz wires in quartz enclosures and generates three magnetic (H z , H r , and H φ ) and two electric (E φ and E r ) field components at the fundamental frequency. The measurements have been performed in rarefied and dense plasmas generated in the electrostatic (E) and electromagnetic (H) discharge modes using two miniature magnetic probes. It is shown that the radial uniformity and depth of the rf power deposition can be improved as compared with conventional sources of inductively coupled plasmas with external flat spiral ('pancake') antennas. Relatively deeper rf power deposition in the plasma source results in more uniform profiles of the optical emission intensity, which indicates on the improvement of the plasma uniformity over large chamber volumes. The results of the numerical modeling of the radial magnetic field profiles are found in a reasonable agreement with the experimental data

  13. Distributed system for large-scale remote research

    International Nuclear Information System (INIS)

    Ueshima, Yutaka

    2002-01-01

    In advanced photon research, large-scale simulations and high-resolution observations are powerfull tools. In numerical and real experiments, the real-time visualization and steering system is considered as a hopeful method of data analysis. This approach is valid in the typical analysis at one time or low cost experiment and simulation. In research of an unknown problem, it is necessary that the output data be analyzed many times because conclusive analysis is difficult at one time. Consequently, output data should be filed to refer and analyze at any time. To support research, we need the automatic functions, transporting data files from data generator to data storage, analyzing data, tracking history of data handling, and so on. The supporting system will be a functionally distributed system. (author)

  14. NASA's Information Power Grid: Large Scale Distributed Computing and Data Management

    Science.gov (United States)

    Johnston, William E.; Vaziri, Arsi; Hinke, Tom; Tanner, Leigh Ann; Feiereisen, William J.; Thigpen, William; Tang, Harry (Technical Monitor)

    2001-01-01

    Large-scale science and engineering are done through the interaction of people, heterogeneous computing resources, information systems, and instruments, all of which are geographically and organizationally dispersed. The overall motivation for Grids is to facilitate the routine interactions of these resources in order to support large-scale science and engineering. Multi-disciplinary simulations provide a good example of a class of applications that are very likely to require aggregation of widely distributed computing, data, and intellectual resources. Such simulations - e.g. whole system aircraft simulation and whole system living cell simulation - require integrating applications and data that are developed by different teams of researchers frequently in different locations. The research team's are the only ones that have the expertise to maintain and improve the simulation code and/or the body of experimental data that drives the simulations. This results in an inherently distributed computing and data management environment.

  15. Distribution and assemblages of large branchiopods (Crustacea: Branchiopoda of northern Western Ghats, India

    Directory of Open Access Journals (Sweden)

    Sameer M. Padhye

    2015-01-01

    Full Text Available The present study is a report on the distribution and assemblages of large branchiopods from the Western Ghats of Maharashtra. Different types of water bodies were sampled including pools on lateritic outcrops. Eight species of large branchiopods were found in 72 samples collected over a period of 4 years. We found 7 large branchiopod species in rock pools, while the cyclestheriid Cyclestheria hislopi was observed only in rivers and water reservoirs. In twenty-five percent of the samples multiple species co-occurred with a maximum of 4 species in a single sample. Streptocephalus dichotomus was the most commonly observed species while Streptocephalus sahyadriensis was noted only in rock pools. Altitude and aquatic vegetation were identified as important factors for the distribution of large branchiopods in the studied area. Triops granarius was the species most commonly found to be co-occurring with other species, followed by S. sahyadriensis. Cyclestheria hislopi and Eulimnadia indocylindrova always occurred alone. 

  16. New large-deviation local theorems for sums of independent and identically distributed random vectors when the limit distribution is α-stable

    OpenAIRE

    Nagaev, Alexander; Zaigraev, Alexander

    2005-01-01

    A class of absolutely continuous distributions in Rd is considered. Each distribution belongs to the domain of normal attraction of an α-stable law. The limit law is characterized by a spectral measure which is absolutely continuous with respect to the spherical Lebesgue measure. The large-deviation problem for sums of independent and identically distributed random vectors when the underlying distribution belongs to that class is studied. At the focus of attention are the deviations in the di...

  17. Measurement of temperature distributions in large pool fires with the use of directional flame thermometers

    International Nuclear Information System (INIS)

    Koski, Jorman A.

    2000-01-01

    Temperatures inside the flame zone of large regulatory pool fires measured during tests of radioactive materials packages vary widely with both time and position. Measurements made with several Directional Flame Thermometers, in which a thermocouple is attached to a thin metal sheet that quickly approaches flame temperatures, have been used to construct fire temperature distributions and cumulative probability distributions. As an aid to computer simulations of these large fires, these distributions are presented. The distributions are constructed by sorting fire temperature data into bins 10 C wide. A typical fire temperature distribution curve has a gradual increase starting at about 600 C, with the number of observations increasing to a peak near 1000 C, followed by an abrupt decrease in frequency, with no temperatures observed above 1200 C

  18. Small-scale distribution and diel vertical migration of zooplankton in a shallow lake (Lake Naardermeer, the Netherlands)

    NARCIS (Netherlands)

    Cerbin, S.; Balayla, D.; Van de Bund, W.J.

    2003-01-01

    Small scale distribution and diurnal migration of zooplankton were investigated in lake Naardermeer, a shallow lake largely covered by uniform Chara beds. For sampling, pattern samplers with a number of inverted funnels facing towards the lake bottom and held in a frame were used. Samplers were

  19. Influence of cathode emission uniformity on microwave generation in relativistic backward wave oscillator

    Science.gov (United States)

    Wu, Ping; Sun, Jun; Teng, Yan

    2017-12-01

    The emission uniformity of explosive emission cathodes is important to the operation of high power microwave generators. Although this concept seems to be widely accepted, the concrete influence of cathode emission uniformity on microwave generation has not been researched in detail and many conclusions on this matter are ambiguous due to the lack of solid evidence. This paper makes an effort to research this issue with particle-in-cell simulations about an X-band relativistic backward wave oscillator. To keep the diode impedance unchanged, an emission model in which each emission cell is artificially assigned a specific current density is adopted. The emission non-uniformity is simulated in three ways: spaced emission, large-area no-emission, and local enhanced emission. The simulation results uncover three phenomena: first, no significant influence is found for the cathode emission uniformity on the microwave starting time as long as no obvious mode competition is excited by emission non-uniformity; second, bad emission uniformity may bring about reduction of microwave power, but this may not happen when the emission non-uniformity is just localized to a few discrete strong emission points; third, under specific circumstances, the emission non-uniformity may lead to the excitation of mode competition, which can significantly delay the starting time and lower the microwave power.

  20. Estimation of customer lifetime value of a health insurance with interest rates obeying uniform distribution

    Science.gov (United States)

    Widyawan, A.; Pasaribu, U. S.; Henintyas, Permana, D.

    2015-12-01

    Nowadays some firms, including insurer firms, think that customer-centric services are better than product-centric ones in terms of marketing. Insurance firms will try to attract as many new customer as possible while maintaining existing customer. This causes the Customer Lifetime Value (CLV) becomes a very important thing. CLV are able to put customer into different segments and calculate the present value of a firm's relationship with its customer. Insurance customer will depend on the last service he or she can get. So if the service is bad now, then customer will not renew his contract though the service is very good at an erlier time. Because of this situation one suitable mathematical model for modeling customer's relationships and calculating their lifetime value is Markov Chain. In addition, the advantages of using Markov Chain Modeling is its high degree of flexibility. In 2000, Pfeifer and Carraway states that Markov Chain Modeling can be used for customer retention situation. In this situation, Markov Chain Modeling requires only two states, which are present customer and former ones. This paper calculates customer lifetime value in an insurance firm with two distinctive interest rates; the constant interest rate and uniform distribution of interest rates. The result shows that loyal customer and the customer who increase their contract value have the highest CLV.

  1. A Directed Acyclic Graph-Large Margin Distribution Machine Model for Music Symbol Classification.

    Directory of Open Access Journals (Sweden)

    Cuihong Wen

    Full Text Available Optical Music Recognition (OMR has received increasing attention in recent years. In this paper, we propose a classifier based on a new method named Directed Acyclic Graph-Large margin Distribution Machine (DAG-LDM. The DAG-LDM is an improvement of the Large margin Distribution Machine (LDM, which is a binary classifier that optimizes the margin distribution by maximizing the margin mean and minimizing the margin variance simultaneously. We modify the LDM to the DAG-LDM to solve the multi-class music symbol classification problem. Tests are conducted on more than 10000 music symbol images, obtained from handwritten and printed images of music scores. The proposed method provides superior classification capability and achieves much higher classification accuracy than the state-of-the-art algorithms such as Support Vector Machines (SVMs and Neural Networks (NNs.

  2. A Local Scalable Distributed EM Algorithm for Large P2P Networks

    Data.gov (United States)

    National Aeronautics and Space Administration — his paper describes a local and distributed expectation maximization algorithm for learning parameters of Gaussian mixture models (GMM) in large peer-to-peer (P2P)...

  3. The spatial distribution of pollutants in pipe-scale of large-diameter pipelines in a drinking water distribution system.

    Science.gov (United States)

    Liu, Jingqing; Chen, Huanyu; Yao, Lingdan; Wei, Zongyuan; Lou, Liping; Shan, Yonggui; Endalkachew, Sahle-Demessie; Mallikarjuna, Nadagouda; Hu, Baolan; Zhou, Xiaoyan

    2016-11-05

    In large-diameter drinking water pipelines, spatial differences in hydraulic and physiochemical conditions may also result in spatial variations in pipe corrosion, biofilm growth and pollutant accumulation. In this article, the spatial distributions of various metals and organic contaminants in two 19-year-old grey cast iron pipes which had an internal diameter of 600mm (DN600), were investigated and analyzed by Atomic Absorption Spectrometry, Gas Chromatography-Mass Spectrometry, Energy Dispersive Spectrometer, X-ray Diffraction, etc. The spatial distribution of heavy metals varied significantly across the pipe section, and iron, manganese, lead, copper, and chromium were highest in concentration in the upper portion pipe-scales. However, the highest aluminum and zinc content was detected in the lower portion pipe-scales. Apart from some common types of hydrocarbons formed by microbial metabolites, there were also some microalgae metabolites and exogenous contaminants accumulated in pipe-scale, which also exhibited high diversity between different spatial locations. The spatial distributions of the physical and chemical properties of pipe-scale and contaminants were quite different in large-diameter pipes. The finding put forward higher requirements on the research method about drinking water distribution system chemical safety. And the scientific community need understand trend and dynamics of drinking water pipe systems better. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. ZnO:Al thin films deposited by RF-magnetron sputtering with tunable and uniform properties.

    Science.gov (United States)

    Miorin, E; Montagner, F; Battiston, S; Fiameni, S; Fabrizio, M

    2011-03-01

    Nanostructured, high quality and large area Al-doped ZnO (ZnO:Al) thin films were obtained by radiofrequency (RF) magnetron sputtering. The sample rotation during deposition has resulted in excellent spatial distribution of thickness and electro-optical properties compared to that obtained under static conditions. ZnO:Al thin films are employed in a large number of devices, including thin film solar cells, where the uniformity of the properties is a key factor for a possible up-scaling of the research results to industrially relevant substrate sizes. A chemical post etching treatment was employed achieving tunable surface nanotextures to generate light scattering at the desired wavelength for improved cell efficiency. Since the film resistivity is only slightly increased by the etching, this post-deposition step allows separating the optimization of electro-optical properties from light scattering behavior. The thin films were characterized by FE-SEM, XRD, UV-VIS spectroscopy, four probe and van der Paw techniques.

  5. Temporal high-pass non-uniformity correction algorithm based on grayscale mapping and hardware implementation

    Science.gov (United States)

    Jin, Minglei; Jin, Weiqi; Li, Yiyang; Li, Shuo

    2015-08-01

    In this paper, we propose a novel scene-based non-uniformity correction algorithm for infrared image processing-temporal high-pass non-uniformity correction algorithm based on grayscale mapping (THP and GM). The main sources of non-uniformity are: (1) detector fabrication inaccuracies; (2) non-linearity and variations in the read-out electronics and (3) optical path effects. The non-uniformity will be reduced by non-uniformity correction (NUC) algorithms. The NUC algorithms are often divided into calibration-based non-uniformity correction (CBNUC) algorithms and scene-based non-uniformity correction (SBNUC) algorithms. As non-uniformity drifts temporally, CBNUC algorithms must be repeated by inserting a uniform radiation source which SBNUC algorithms do not need into the view, so the SBNUC algorithm becomes an essential part of infrared imaging system. The SBNUC algorithms' poor robustness often leads two defects: artifacts and over-correction, meanwhile due to complicated calculation process and large storage consumption, hardware implementation of the SBNUC algorithms is difficult, especially in Field Programmable Gate Array (FPGA) platform. The THP and GM algorithm proposed in this paper can eliminate the non-uniformity without causing defects. The hardware implementation of the algorithm only based on FPGA has two advantages: (1) low resources consumption, and (2) small hardware delay: less than 20 lines, it can be transplanted to a variety of infrared detectors equipped with FPGA image processing module, it can reduce the stripe non-uniformity and the ripple non-uniformity.

  6. Forecasting distributions of large federal-lands fires utilizing satellite and gridded weather information

    Science.gov (United States)

    H.K. Preisler; R.E. Burgan; J.C. Eidenshink; J.M. Klaver; R.W. Klaver

    2009-01-01

    The current study presents a statistical model for assessing the skill of fire danger indices and for forecasting the distribution of the expected numbers of large fires over a given region and for the upcoming week. The procedure permits development of daily maps that forecast, for the forthcoming week and within federal lands, percentiles of the distributions of (i)...

  7. Distributed constraint satisfaction for coordinating and integrating a large-scale, heterogenous enterprise

    CERN Document Server

    Eisenberg, C

    2003-01-01

    Market forces are continuously driving public and private organisations towards higher productivity, shorter process and production times, and fewer labour hours. To cope with these changes, organisations are adopting new organisational models of coordination and cooperation that increase their flexibility, consistency, efficiency, productivity and profit margins. In this thesis an organisational model of coordination and cooperation is examined using a real life example; the technical integration of a distributed large-scale project of an international physics collaboration. The distributed resource constraint project scheduling problem is modelled and solved with the methods of distributed constraint satisfaction. A distributed local search method, the distributed breakout algorithm (DisBO), is used as the basis for the coordination scheme. The efficiency of the local search method is improved by extending it with an incremental problem solving scheme with variable ordering. The scheme is implemented as cen...

  8. A Monte Carlo study of the impact of the choice of rectum volume definition on estimates of equivalent uniform doses and the volume parameter

    International Nuclear Information System (INIS)

    Kvinnsland, Yngve; Muren, Ludvig Paul; Dahl, Olav

    2004-01-01

    Calculations of normal tissue complication probability (NTCP) values for the rectum are difficult because it is a hollow, non-rigid, organ. Finding the true cumulative dose distribution for a number of treatment fractions requires a CT scan before each treatment fraction. This is labour intensive, and several surrogate distributions have therefore been suggested, such as dose wall histograms, dose surface histograms and histograms for the solid rectum, with and without margins. In this study, a Monte Carlo method is used to investigate the relationships between the cumulative dose distributions based on all treatment fractions and the above-mentioned histograms that are based on one CT scan only, in terms of equivalent uniform dose. Furthermore, the effect of a specific choice of histogram on estimates of the volume parameter of the probit NTCP model was investigated. It was found that the solid rectum and the rectum wall histograms (without margins) gave equivalent uniform doses with an expected value close to the values calculated from the cumulative dose distributions in the rectum wall. With the number of patients available in this study the standard deviations of the estimates of the volume parameter were large, and it was not possible to decide which volume gave the best estimates of the volume parameter, but there were distinct differences in the mean values of the values obtained

  9. Additive non-uniform random sampling in superimposed fiber Bragg grating strain gauge

    Science.gov (United States)

    Ma, Y. C.; Liu, H. Y.; Yan, S. B.; Yang, Y. H.; Yang, M. W.; Li, J. M.; Tang, J.

    2013-05-01

    This paper demonstrates an additive non-uniform random sampling and interrogation method for dynamic and/or static strain gauge using a reflection spectrum from two superimposed fiber Bragg gratings (FBGs). The superimposed FBGs are designed to generate non-equidistant space of a sensing pulse train in the time domain during dynamic strain gauge. By combining centroid finding with smooth filtering methods, both the interrogation speed and accuracy are improved. A 1.9 kHz dynamic strain is measured by generating an additive non-uniform randomly distributed 2 kHz optical sensing pulse train from a mean 500 Hz triangular periodically changing scanning frequency.

  10. Uniform-sized silicone oil microemulsions: preparation, investigation of stability and deposition on hair surface.

    Science.gov (United States)

    Nazir, Habiba; Lv, Piping; Wang, Lianyan; Lian, Guoping; Zhu, Shiping; Ma, Guanghui

    2011-12-01

    Emulsions are commonly used in foods, pharmaceuticals and home-personal-care products. For emulsion based products, it is highly desirable to control the droplet size distribution to improve storage stability, appearance and in-use property. We report preparation of uniform-sized silicone oil microemulsions with different droplets diameters (1.4-40.0 μm) using SPG membrane emulsification technique. These microemulsions were then added into model shampoos and conditioners to investigate the effects of size, uniformity, and storage stability on silicone oil deposition on hair surface. We observed much improved storage stability of uniform-sized microemulsions when the droplets diameter was ≤22.7 μm. The uniform-sized microemulsion of 40.0 μm was less stable but still more stable than non-uniform sized microemulsions prepared by conventional homogenizer. The results clearly indicated that uniform-sized droplets enhanced the deposition of silicone oil on hair and deposition increased with decreasing droplet size. Hair switches washed with small uniform-sized droplets had lower values of coefficient of friction compared with those washed with larger uniform and non-uniform droplets. Moreover the addition of alginate thickener in the shampoos and conditioners further enhanced the deposition of silicone oil on hair. The good correlation between silicone oil droplets stability, deposition on hair and resultant friction of hair support that droplet size and uniformity are important factors for controlling the stability and deposition property of emulsion based products such as shampoo and conditioner. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. Sequential Uniformly Reweighted Sum-Product Algorithm for Cooperative Localization in Wireless Networks

    OpenAIRE

    Li, Wei; Yang, Zhen; Hu, Haifeng

    2014-01-01

    Graphical models have been widely applied in solving distributed inference problems in wireless networks. In this paper, we formulate the cooperative localization problem in a mobile network as an inference problem on a factor graph. Using a sequential schedule of message updates, a sequential uniformly reweighted sum-product algorithm (SURW-SPA) is developed for mobile localization problems. The proposed algorithm combines the distributed nature of belief propagation (BP) with the improved p...

  12. Toward Cooling Uniformity: Investigation of Spiral, Sweeping Holes, and Unconventional Cooling Paradigms

    Science.gov (United States)

    Shyam, Vikram; Thurman, Douglas R.; Poinsatte, Philip E.; Ameri, Ali A.; Culley, Dennis E.

    2018-01-01

    Surface infrared thermography, hotwire anemometry, and thermocouple surveys were performed on two new film cooling hole geometries: spiral/rifled holes and fluidic sweeping holes. Ways to quantify the efficacy of novel cooling holes that are asymmetric, not uniformly spaced or that show variation from hole to hole are presented. The spiral holes attempt to induce large-scale vorticity to the film cooling jet as it exits the hole to prevent the formation of the kidney shaped vortices commonly associated with film cooling jets. The fluidic sweeping hole uses a passive in-hole geometry to induce jet sweeping at frequencies that scale with blowing ratios. The spiral hole performance is compared to that of round holes with and without compound angles. The fluidic hole is of the diffusion class of holes and is therefore compared to a 777 hole and square holes. A patent-pending spiral hole design showed the highest potential of the nondiffusion type hole configurations. Velocity contours and flow temperature were acquired at discreet cross-sections of the downstream flow field. The passive fluidic sweeping hole shows the most uniform cooling distribution but suffers from low span-averaged effectiveness levels due to enhanced mixing. The data was taken at a Reynolds number of 11,000 based on hole diameter and freestream velocity. Infrared thermography was taken for blowing ratios of 1.0, 1.5, 2.0, and 2.5 at a density ratio of 1.05. The flow inside the fluidic sweeping hole was studied using 3D unsteady RANS. A section on ideas for future work is included that addresses issues of quantifying cooling uniformity and provides some ideas for changing the way we think about cooling such as changing the direction of cooling or coupling acoustic devices to cooling holes to regulate frequency.

  13. Galaxies distribution in the universe: large-scale statistics and structures

    International Nuclear Information System (INIS)

    Maurogordato, Sophie

    1988-01-01

    This research thesis addresses the distribution of galaxies in the Universe, and more particularly large scale statistics and structures. Based on an assessment of the main used statistical techniques, the author outlines the need to develop additional tools to correlation functions in order to characterise the distribution. She introduces a new indicator: the probability of a volume randomly tested in the distribution to be void. This allows a characterisation of void properties at the work scales (until 10h"-"1 Mpc) in the Harvard Smithsonian Center for Astrophysics Redshift Survey, or CfA catalog. A systematic analysis of statistical properties of different sub-samples has then been performed with respect to the size and location, luminosity class, and morphological type. This analysis is then extended to different scenarios of structure formation. A program of radial speed measurements based on observations allows the determination of possible relationships between apparent structures. The author also presents results of the search for south extensions of Perseus supernova [fr

  14. A Topology Visualization Early Warning Distribution Algorithm for Large-Scale Network Security Incidents

    Directory of Open Access Journals (Sweden)

    Hui He

    2013-01-01

    Full Text Available It is of great significance to research the early warning system for large-scale network security incidents. It can improve the network system’s emergency response capabilities, alleviate the cyber attacks’ damage, and strengthen the system’s counterattack ability. A comprehensive early warning system is presented in this paper, which combines active measurement and anomaly detection. The key visualization algorithm and technology of the system are mainly discussed. The large-scale network system’s plane visualization is realized based on the divide and conquer thought. First, the topology of the large-scale network is divided into some small-scale networks by the MLkP/CR algorithm. Second, the sub graph plane visualization algorithm is applied to each small-scale network. Finally, the small-scale networks’ topologies are combined into a topology based on the automatic distribution algorithm of force analysis. As the algorithm transforms the large-scale network topology plane visualization problem into a series of small-scale network topology plane visualization and distribution problems, it has higher parallelism and is able to handle the display of ultra-large-scale network topology.

  15. Distribution of hadron intranuclear cascade for large distance from a source

    International Nuclear Information System (INIS)

    Bibin, V.L.; Kazarnovskij, M.V.; Serezhnikov, S.V.

    1985-01-01

    Analytical solution of the problem of three-component hadron cascade development for large distances from a source is obtained in the framework of a series of simplifying assumptions. It makes possible to understand physical mechanisms of the process studied and to obtain approximate asymptotic expressions for hadron distribution functions

  16. Free vibration analysis of a robotic fish based on a continuous and non-uniform flexible backbone with distributed masses

    Science.gov (United States)

    Coral, W.; Rossi, C.; Curet, O. M.

    2015-12-01

    This paper presents a Differential Quadrature Element Method for free transverse vibration of a robotic fish based on a continuous and non-uniform flexible backbone with distributed masses (fish ribs). The proposed method is based on the theory of a Timoshenko cantilever beam. The effects of the masses (number, magnitude and position) on the value of natural frequencies are investigated. Governing equations, compatibility and boundary conditions are formulated according to the Differential Quadrature rules. The convergence, efficiency and accuracy are compared to other analytical solution proposed in the literature. Moreover, the proposed method has been validate against the physical prototype of a flexible fish backbone. The main advantages of this method, compared to the exact solutions available in the literature are twofold: first, smaller computational cost and second, it allows analysing the free vibration in beams whose section is an arbitrary function, which is normally difficult or even impossible with other analytical methods.

  17. Particle-in-cell simulation of electron trajectories and irradiation uniformity in an annular cathode high current pulsed electron beam source

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Wei; Wang, Langping, E-mail: aplpwang@hit.edu.cn; Zhou, Guangxue; Wang, Xiaofeng

    2017-02-01

    Highlights: • The transmission process of electrons and irradiation uniformity was simulated. • Influence of the irradiation parameters on irradiation uniformity are discussed. • High irradiation uniformity can be obtained in a wide processing window. - Abstract: In order to study electron trajectories in an annular cathode high current pulsed electron beam (HCPEB) source based on carbon fiber bunches, the transmission process of electrons emitted from the annular cathode was simulated using a particle-in-cell model with Monte Carlo collisions (PIC-MCC). The simulation results show that the intense flow of the electrons emitted from the annular cathode are expanded during the transmission process, and the uniformity of the electron distribution is improved in the transportation process. The irradiation current decreases with the irradiation distance and the pressure, and increases with the negative voltage. In addition, when the irradiation distance and the cathode voltage are larger than 40 mm and −15 kV, respectively, a uniform irradiation current distribution along the circumference of the anode can be obtained. The simulation results show that good irradiation uniformity of circular components can be achieved by this annular cathode HCPEB source.

  18. Controlling Growth High Uniformity Indium Selenide (In2Se3) Nanowires via the Rapid Thermal Annealing Process at Low Temperature.

    Science.gov (United States)

    Hsu, Ya-Chu; Hung, Yu-Chen; Wang, Chiu-Yen

    2017-09-15

    High uniformity Au-catalyzed indium selenide (In 2 Se 3) nanowires are grown with the rapid thermal annealing (RTA) treatment via the vapor-liquid-solid (VLS) mechanism. The diameters of Au-catalyzed In 2 Se 3 nanowires could be controlled with varied thicknesses of Au films, and the uniformity of nanowires is improved via a fast pre-annealing rate, 100 °C/s. Comparing with the slower heating rate, 0.1 °C/s, the average diameters and distributions (standard deviation, SD) of In 2 Se 3 nanowires with and without the RTA process are 97.14 ± 22.95 nm (23.63%) and 119.06 ± 48.75 nm (40.95%), respectively. The in situ annealing TEM is used to study the effect of heating rate on the formation of Au nanoparticles from the as-deposited Au film. The results demonstrate that the average diameters and distributions of Au nanoparticles with and without the RTA process are 19.84 ± 5.96 nm (30.00%) and about 22.06 ± 9.00 nm (40.80%), respectively. It proves that the diameter size, distribution, and uniformity of Au-catalyzed In 2 Se 3 nanowires are reduced and improved via the RTA pre-treated. The systemic study could help to control the size distribution of other nanomaterials through tuning the annealing rate, temperatures of precursor, and growth substrate to control the size distribution of other nanomaterials. Graphical Abstract Rapid thermal annealing (RTA) process proved that it can uniform the size distribution of Au nanoparticles, and then it can be used to grow the high uniformity Au-catalyzed In 2 Se 3 nanowires via the vapor-liquid-solid (VLS) mechanism. Comparing with the general growth condition, the heating rate is slow, 0.1 °C/s, and the growth temperature is a relatively high growth temperature, > 650 °C. RTA pre-treated growth substrate can form smaller and uniform Au nanoparticles to react with the In 2 Se 3 vapor and produce the high uniformity In 2 Se 3 nanowires. The in situ annealing TEM is used to realize the effect of heating

  19. Numerical Prediction of the Influence of Process Parameters on Large Area Diamond Deposition by DC Arcjet with ARC Roots Rotating and Operating at Gas Recycling Mode

    Science.gov (United States)

    Lu, F. X.; Huang, T. B.; Tang, W. Z.; Song, J. H.; Tong, Y. M.

    A computer model have been set up for simulation of the flow and temperature field, and the radial distribution of atomic hydrogen and active carbonaceous species over a large area substrate surface for a new type dc arc plasma torch with rotating arc roots and operating at gas recycling mode A gas recycling radio of 90% was assumed. In numerical calculation of plasma chemistry, the Thermal-Calc program and a powerful thermodynamic database were employed. Numerical calculations to the computer model were performed using boundary conditions close to the experimental setup for large area diamond films deposition. The results showed that the flow and temperature field over substrate surface of Φ60-100mm were smooth and uniform. Calculations were also made with plasma of the same geometry but no arc roots rotation. It was clearly demonstrated that the design of rotating arc roots was advantageous for high quality uniform deposition of large area diamond films. Theoretical predictions on growth rate and film quality as well as their radial uniformity, and the influence of process parameters on large area diamond deposition were discussed in detail based on the spatial distribution of atomic hydrogen and the carbonaceous species in the plasma over the substrate surface obtained from thermodynamic calculations of plasma chemistry, and were compared with experimental observations.

  20. On locally uniformly linearizable high breakdown location and scale functionals

    NARCIS (Netherlands)

    Davies, P.L.

    1998-01-01

    This article gives two constructions of a weighted mean which has a large domain, is affinely equivariant, has a locally high breakdown point and is locally uniformly linearizable. One construction is based on $M$-functionals with smooth defining $\\psi$- and $\\chi$ -functions which are used to

  1. A Matrix-Based Proactive Data Relay Algorithm for Large Distributed Sensor Networks.

    Science.gov (United States)

    Xu, Yang; Hu, Xuemei; Hu, Haixiao; Liu, Ming

    2016-08-16

    In large-scale distributed sensor networks, sensed data is required to be relayed around the network so that one or few sensors can gather adequate relative data to produce high quality information for decision-making. In regards to very high energy-constraint sensor nodes, data transmission should be extremely economical. However, traditional data delivery protocols are potentially inefficient relaying unpredictable sensor readings for data fusion in large distributed networks for either overwhelming query transmissions or unnecessary data coverage. By building sensors' local model from their previously transmitted data in three matrixes, we have developed a novel energy-saving data relay algorithm, which allows sensors to proactively make broadcast decisions by using a neat matrix computation to provide balance between transmission and energy-saving. In addition, we designed a heuristic maintenance algorithm to efficiently update these three matrices. This can easily be deployed to large-scale mobile networks in which decisions of sensors are based on their local matrix models no matter how large the network is, and the local models of these sensors are updated constantly. Compared with some traditional approaches based on our simulations, the efficiency of this approach is manifested in uncertain environment. The results show that our approach is scalable and can effectively balance aggregating data with minimizing energy consumption.

  2. Uniform competency-based local feature extraction for remote sensing images

    Science.gov (United States)

    Sedaghat, Amin; Mohammadi, Nazila

    2018-01-01

    Local feature detectors are widely used in many photogrammetry and remote sensing applications. The quantity and distribution of the local features play a critical role in the quality of the image matching process, particularly for multi-sensor high resolution remote sensing image registration. However, conventional local feature detectors cannot extract desirable matched features either in terms of the number of correct matches or the spatial and scale distribution in multi-sensor remote sensing images. To address this problem, this paper proposes a novel method for uniform and robust local feature extraction for remote sensing images, which is based on a novel competency criterion and scale and location distribution constraints. The proposed method, called uniform competency (UC) local feature extraction, can be easily applied to any local feature detector for various kinds of applications. The proposed competency criterion is based on a weighted ranking process using three quality measures, including robustness, spatial saliency and scale parameters, which is performed in a multi-layer gridding schema. For evaluation, five state-of-the-art local feature detector approaches, namely, scale-invariant feature transform (SIFT), speeded up robust features (SURF), scale-invariant feature operator (SFOP), maximally stable extremal region (MSER) and hessian-affine, are used. The proposed UC-based feature extraction algorithms were successfully applied to match various synthetic and real satellite image pairs, and the results demonstrate its capability to increase matching performance and to improve the spatial distribution. The code to carry out the UC feature extraction is available from href="https://www.researchgate.net/publication/317956777_UC-Feature_Extraction.

  3. SYVAC3 parameter distribution package

    Energy Technology Data Exchange (ETDEWEB)

    Andres, T; Skeet, A

    1995-01-01

    SYVAC3 (Systems Variability Analysis Code, generation 3) is a computer program that implements a method called systems variability analysis to analyze the behaviour of a system in the presence of uncertainty. This method is based on simulating the system many times to determine the variation in behaviour it can exhibit. SYVAC3 specializes in systems representing the transport of contaminants, and has several features to simplify the modelling of such systems. It provides a general tool for estimating environmental impacts from the dispersal of contaminants. This report describes a software object type (a generalization of a data type) called Parameter Distribution. This object type is used in SYVAC3, and can also be used independently. Parameter Distribution has the following subtypes: beta distribution; binomial distribution; constant distribution; lognormal distribution; loguniform distribution; normal distribution; piecewise uniform distribution; Triangular distribution; and uniform distribution. Some of these distributions can be altered by correlating two parameter distribution objects. This report provides complete specifications for parameter distributions, and also explains how to use them. It should meet the needs of casual users, reviewers, and programmers who wish to add their own subtypes. (author). 30 refs., 75 tabs., 56 figs.

  4. The segmented non-uniform dielectric module design for uniformity control of plasma profile in a capacitively coupled plasma chamber

    International Nuclear Information System (INIS)

    Xia, Huanxiong; Xiang, Dong; Yang, Wang; Mou, Peng

    2014-01-01

    Low-temperature plasma technique is one of the critical techniques in IC manufacturing process, such as etching and thin-film deposition, and the uniformity greatly impacts the process quality, so the design for the plasma uniformity control is very important but difficult. It is hard to finely and flexibly regulate the spatial distribution of the plasma in the chamber via controlling the discharge parameters or modifying the structure in zero-dimensional space, and it just can adjust the overall level of the process factors. In the view of this problem, a segmented non-uniform dielectric module design solution is proposed for the regulation of the plasma profile in a CCP chamber. The solution achieves refined and flexible regulation of the plasma profile in the radial direction via configuring the relative permittivity and the width of each segment. In order to solve this design problem, a novel simulation-based auto-design approach is proposed, which can automatically design the positional sequence with multi independent variables to make the output target profile in the parameterized simulation model approximate the one that users preset. This approach employs an idea of quasi-closed-loop control system, and works in an iterative mode. It starts from initial values of the design variable sequences, and predicts better sequences via the feedback of the profile error between the output target profile and the expected one. It never stops until the profile error is narrowed in the preset tolerance

  5. 46 CFR 310.11 - Cadet uniforms.

    Science.gov (United States)

    2010-10-01

    ... for State, Territorial or Regional Maritime Academies and Colleges § 310.11 Cadet uniforms. Cadet uniforms shall be supplied at the school in accordance with the uniform regulations of the School. Those... 46 Shipping 8 2010-10-01 2010-10-01 false Cadet uniforms. 310.11 Section 310.11 Shipping MARITIME...

  6. Numerical Study on the Effect of Distribution Plates in the Manifolds on the Flow Distribution and Thermal Performance of a Flat Plate Solar Collector

    Directory of Open Access Journals (Sweden)

    Juan Manuel García-Guendulain

    2018-04-01

    Full Text Available Flow maldistribution represents a problem of particular interest in the engineering field for several thermal systems. In flat plate solar collectors, the thermal efficiency strongly depends on the flow distribution through the riser tubes, where a uniform distribution causes a uniform temperature distribution and therefore a higher efficiency. In this work, a Computational Fluid Dynamics (CFD numerical analysis has been carried out using the commercial software FLUENT®, in order to determine the flow distribution, pressure drop and hence the thermal efficiency of a solar collector with distribution flow plates inside the manifolds. The obtained numerical solution for this type of thermal systems has been validated with experimental results available in literature for laminar and turbulent flow. Four distribution plate configurations were analyzed. Results show that using two distribution plates in each of both manifolds improves the flow uniformity up to 40% under the same operating conditions when distribution plates are not used. Besides, it is shown that there exists an increase in the overall pressure drop which is practically negligible for the tilt angles commonly employed in the installation of flat plate solar collectors in Mexico. The use of closed end distribution plates on the dividing and combining manifolds allows the thermal efficiency to become close to the ideal thermal efficiency which is obtained with a uniform flow distribution.

  7. A Parallel Distributed-Memory Particle Method Enables Acquisition-Rate Segmentation of Large Fluorescence Microscopy Images.

    Science.gov (United States)

    Afshar, Yaser; Sbalzarini, Ivo F

    2016-01-01

    Modern fluorescence microscopy modalities, such as light-sheet microscopy, are capable of acquiring large three-dimensional images at high data rate. This creates a bottleneck in computational processing and analysis of the acquired images, as the rate of acquisition outpaces the speed of processing. Moreover, images can be so large that they do not fit the main memory of a single computer. We address both issues by developing a distributed parallel algorithm for segmentation of large fluorescence microscopy images. The method is based on the versatile Discrete Region Competition algorithm, which has previously proven useful in microscopy image segmentation. The present distributed implementation decomposes the input image into smaller sub-images that are distributed across multiple computers. Using network communication, the computers orchestrate the collectively solving of the global segmentation problem. This not only enables segmentation of large images (we test images of up to 10(10) pixels), but also accelerates segmentation to match the time scale of image acquisition. Such acquisition-rate image segmentation is a prerequisite for the smart microscopes of the future and enables online data compression and interactive experiments.

  8. Should School Nurses Wear Uniforms?

    Science.gov (United States)

    Journal of School Health, 2001

    2001-01-01

    This 1958 paper questions whether school nurses should wear uniforms (specifically, white uniforms). It concludes that white uniforms are often associated with the treatment of ill people, and since many people have a fear reaction to them, they are not necessary and are even undesirable. Since school nurses are school staff members, they should…

  9. Efficient SPECT scatter calculation in non-uniform media using correlated Monte Carlo simulation

    International Nuclear Information System (INIS)

    Beekman, F.J.

    1999-01-01

    Accurate simulation of scatter in projection data of single photon emission computed tomography (SPECT) is computationally extremely demanding for activity distribution in non-uniform dense media. This paper suggests how the computation time and memory requirements can be significantly reduced. First the scatter projection of a uniform dense object (P SDSE ) is calculated using a previously developed accurate and fast method which includes all orders of scatter (slab-derived scatter estimation), and then P SDSE is transformed towards the desired projection P which is based on the non-uniform object. The transform of P SDSE is based on two first-order Compton scatter Monte Carlo (MC) simulated projections. One is based on the uniform object (P u ) and the other on the object with non-uniformities (P ν ). P is estimated by P-tilde=P SDSE P ν /P u . A tremendous decrease in noise in P-tilde is achieved by tracking photon paths for P ν identical to those which were tracked for the calculation of P u and by using analytical rather than stochastic modelling of the collimator. The method was validated by comparing the results with standard MC-simulated scatter projections (P) of 99m Tc and 201 Tl point sources in a digital thorax phantom. After correction, excellent agreement was obtained between P-tilde and P. The total computation time required to calculate an accurate scatter projection of an extended distribution in a thorax phantom on a PC is a only few tens of seconds per projection, which makes the method attractive for application in accurate scatter correction in clinical SPECT. Furthermore, the method removes the need of excessive computer memory involved with previously proposed 3D model-based scatter correction methods. (author)

  10. Dynamics beyond uniform hyperbolicity a global geometric and probabilistic perspective

    CERN Document Server

    Bonatti, Christian; Viana, Marcelo

    2005-01-01

    The notion of uniform hyperbolicity, introduced by Steve Smale in the early sixties, unified important developments and led to a remarkably successful theory for a large class of systems: uniformly hyperbolic systems often exhibit complicated evolution which, nevertheless, is now rather well understood, both geometrically and statistically.Another revolution has been taking place in the last couple of decades, as one tries to build a global theory for "most" dynamical systems, recovering as much as possible of the conclusions of the uniformly hyperbolic case, in great generality. This book aims to put such recent developments in a unified perspective, and to point out open problems and likely directions for further progress. It is aimed at researchers, both young and senior, willing to get a quick, yet broad, view of this part of dynamics. Main ideas, methods, and results are discussed, at variable degrees of depth, with references to the original works for details and complementary information.

  11. Metallic nanocone array photonic substrate for high-uniformity surface deposition and optical detection of small molecules

    International Nuclear Information System (INIS)

    Coppe, Jean-Philippe; Xu Zhida; Chen Yi; Logan Liu, G

    2011-01-01

    Molecular probe arrays printed on solid surfaces such as DNA, peptide, and protein microarrays are widely used in chemical and biomedical applications especially genomic and proteomic studies (Pollack et al 1999 Nat. Genet. 23 41-6, Houseman et al 2002 Nat. Biotechnol. 20 270-4, Sauer et al 2005 Nat. Rev. Genet. 6 465-76) as well as surface imaging and spectroscopy (Mori et al 2008 Anal. Biochem. 375 223-31, Liu et al 2006 Nat. Nanotechnol. 1 47-52, Liu 2010 IEEE J. Sel. Top. Quantum Electron. 16 662-71). Unfortunately the printed molecular spots on solid surfaces often suffer low distribution uniformity due to the lingering 'coffee stain' (Deegan et al 1997 Nature 389 827-9) problem of molecular accumulations and blotches, especially around the edge of deposition spots caused by solvent evaporation and convection processes. Here we present, without any surface chemistry modification, a unique solid surface of high-aspect-ratio silver-coated silicon nanocone arrays that allows highly uniform molecular deposition and thus subsequent uniform optical imaging and spectroscopic molecular detection. Both fluorescent Rhodamine dye molecules and unlabeled oligopeptides are printed on the metallic nanocone photonic substrate surface as circular spot arrays. In comparison with the printed results on ordinary glass slides and silver-coated glass slides, not only high printing density but uniform molecular distribution in every deposited spot is achieved. The high-uniformity and repeatability of molecular depositions on the 'coffee stain'-free nanocone surface is confirmed by laser scanning fluorescence imaging and surface enhanced Raman imaging experiments. The physical mechanism for the uniform molecular deposition is attributed to the superhydrophobicity and localized pinned liquid-solid-air interface on the silver-coated silicon nanocone surface. The unique surface properties of the presented nanocone surface enabled high-density, high-uniformity probe spotting beneficial

  12. Modified distribution parameter for churn-turbulent flows in large diameter channels

    Energy Technology Data Exchange (ETDEWEB)

    Schlegel, J.P., E-mail: jschlege@purdue.edu; Macke, C.J.; Hibiki, T.; Ishii, M.

    2013-10-15

    Highlights: • Void fraction data collected in pipe sizes up to 0.304 m using impedance void meters. • Flow conditions extend to transition between churn-turbulent and annular flow. • Flow regime identification results agree with previous studies. • A new model for the distribution parameter in churn-turbulent flow is proposed. -- Abstract: Two phase flows in large diameter channels are important in a wide range of industrial applications, but especially in analysis of nuclear reactor safety for the prediction of BWR behavior and safety analysis in PWRs. To remedy an inability of current drift-flux models to accurately predict the void fraction in churn-turbulent flows in large diameter pipes, extensive experiments have been performed in pipes with diameters of 0.152 m, 0.203 m and 0.304 m to collect area-averaged void fraction data using electrical impedance void meters. The standard deviation and skewness of the impedance meter signal have been used to characterize the flow regime and confirm previous flow regime transition results. By treating churn-turbulent flow as a transition between cap-bubbly dispersed flow and annular separated flow and using a linear ramp, the distribution parameter has been modified for churn-turbulent flow. The modified distribution parameter has been evaluated through comparison of the void fraction predicted by the drift-flux model and the measured void fraction.

  13. Modified distribution parameter for churn-turbulent flows in large diameter channels

    International Nuclear Information System (INIS)

    Schlegel, J.P.; Macke, C.J.; Hibiki, T.; Ishii, M.

    2013-01-01

    Highlights: • Void fraction data collected in pipe sizes up to 0.304 m using impedance void meters. • Flow conditions extend to transition between churn-turbulent and annular flow. • Flow regime identification results agree with previous studies. • A new model for the distribution parameter in churn-turbulent flow is proposed. -- Abstract: Two phase flows in large diameter channels are important in a wide range of industrial applications, but especially in analysis of nuclear reactor safety for the prediction of BWR behavior and safety analysis in PWRs. To remedy an inability of current drift-flux models to accurately predict the void fraction in churn-turbulent flows in large diameter pipes, extensive experiments have been performed in pipes with diameters of 0.152 m, 0.203 m and 0.304 m to collect area-averaged void fraction data using electrical impedance void meters. The standard deviation and skewness of the impedance meter signal have been used to characterize the flow regime and confirm previous flow regime transition results. By treating churn-turbulent flow as a transition between cap-bubbly dispersed flow and annular separated flow and using a linear ramp, the distribution parameter has been modified for churn-turbulent flow. The modified distribution parameter has been evaluated through comparison of the void fraction predicted by the drift-flux model and the measured void fraction

  14. Inverse analysis of non-uniform temperature distributions using multispectral pyrometry

    Science.gov (United States)

    Fu, Tairan; Duan, Minghao; Tian, Jibin; Shi, Congling

    2016-05-01

    Optical diagnostics can be used to obtain sub-pixel temperature information in remote sensing. A multispectral pyrometry method was developed using multiple spectral radiation intensities to deduce the temperature area distribution in the measurement region. The method transforms a spot multispectral pyrometer with a fixed field of view into a pyrometer with enhanced spatial resolution that can give sub-pixel temperature information from a "one pixel" measurement region. A temperature area fraction function was defined to represent the spatial temperature distribution in the measurement region. The method is illustrated by simulations of a multispectral pyrometer with a spectral range of 8.0-13.0 μm measuring a non-isothermal region with a temperature range of 500-800 K in the spot pyrometer field of view. The inverse algorithm for the sub-pixel temperature distribution (temperature area fractions) in the "one pixel" verifies this multispectral pyrometry method. The results show that an improved Levenberg-Marquardt algorithm is effective for this ill-posed inverse problem with relative errors in the temperature area fractions of (-3%, 3%) for most of the temperatures. The analysis provides a valuable reference for the use of spot multispectral pyrometers for sub-pixel temperature distributions in remote sensing measurements.

  15. Diagnose of large area electron beam with faraday cup

    International Nuclear Information System (INIS)

    Tang Ying; Qian Hang; Yi Aiping; Huang Xin; Yu Li; Liu Jingru; Su Jiancang; Ding Zhenjie; Ding Yongzhong; Yu Jianguo

    2008-01-01

    In the experiment of gas laser pumped by electron beam, large area uniform electron beam is important to generate high efficiency laser output. This paper introduces Faraday cup is used in the diagnose experiment on the uniformity of large area e-beam generated by SPG-200 pulsed power generator. Construction of Faraday cup and the results of calibration are presented in detail. The uniformity of velvet emission is given, and the results of experiment are analyzed. (authors)

  16. Fast crawling methods of exploring content distributed over large graphs

    KAUST Repository

    Wang, Pinghui

    2018-03-15

    Despite recent effort to estimate topology characteristics of large graphs (e.g., online social networks and peer-to-peer networks), little attention has been given to develop a formal crawling methodology to characterize the vast amount of content distributed over these networks. Due to the large-scale nature of these networks and a limited query rate imposed by network service providers, exhaustively crawling and enumerating content maintained by each vertex is computationally prohibitive. In this paper, we show how one can obtain content properties by crawling only a small fraction of vertices and collecting their content. We first show that when sampling is naively applied, this can produce a huge bias in content statistics (i.e., average number of content replicas). To remove this bias, one may use maximum likelihood estimation to estimate content characteristics. However, our experimental results show that this straightforward method requires to sample most vertices to obtain accurate estimates. To address this challenge, we propose two efficient estimators: special copy estimator (SCE) and weighted copy estimator (WCE) to estimate content characteristics using available information in sampled content. SCE uses the special content copy indicator to compute the estimate, while WCE derives the estimate based on meta-information in sampled vertices. We conduct experiments on a variety of real-word and synthetic datasets, and the results show that WCE and SCE are cost effective and also “asymptotically unbiased”. Our methodology provides a new tool for researchers to efficiently query content distributed in large-scale networks.

  17. Control of thickness uniformity and grain size in graphene films for transparent conductive electrodes

    International Nuclear Information System (INIS)

    Wu Wei; Yu Qingkai; Pei, Shin-Shem; Peng Peng; Bao Jiming; Liu Zhihong

    2012-01-01

    Large-scale and transferable graphene films grown on metal substrates by chemical vapor deposition (CVD) still hold great promise for future nanotechnology. To realize the promise, one of the key issues is to further improve the quality of graphene, e.g., uniform thickness, large grain size, and low defects. Here we grow graphene films on Cu foils by CVD at ambient pressure, and study the graphene nucleation and growth processes under different concentrations of carbon precursor. On the basis of the results, we develop a two-step ambient pressure CVD process to synthesize continuous single-layer graphene films with large grain size (up to hundreds of square micrometers). Scanning electron microscopy and Raman spectroscopy characterizations confirm the film thickness and uniformity. The transferred graphene films on cover glass slips show high electrical conductivity and high optical transmittance that make them suitable as transparent conductive electrodes. The growth mechanism of CVD graphene on Cu is also discussed, and a growth model has been proposed. Our results provide important guidance toward the synthesis of high quality uniform graphene films, and could offer a great driving force for graphene based applications. (paper)

  18. Current distribution in parallel paths of the coils of a 50 Hz prototype dipole magnet

    International Nuclear Information System (INIS)

    Otter, A.J.

    1995-06-01

    The prototype dipole made for TRIUMF's Kaon Factory proposal used coils with 12 parallel paths to reduce eddy current losses in the conductors. The ac current distribution in these paths was non-uniform due to different self and mutual inductances. Small differences in inductance can cause large circulating currents in the parallel windings. This paper describes the measurement of the inductances and shows an attempt to predict the current distribution for two alternative connection schemes. (author). 4 refs., 8 figs

  19. Development of the systems for uniform target irradiation

    International Nuclear Information System (INIS)

    Voronin, A.Yu.; Garanin, S.G.; Derkach, V.N.; Zhidkov, N.V.; Kravchenko, A.G.; Petrazhitskaya, N.A.; Starodubtsev, K.V.; Sukharev, S.A.; Shnyagin, R.A.

    2010-01-01

    Complete text of publication follows. The new devices have been developed for laser beams homogenizing in the focal spot - multi-component lens raster and raster with the edges smoothing phase mask. The envelope non-uniformity of -4 radians. Investigation into the temporary-spatial smoothing with the use of low-density foams with the density less than the critical one is still in progress. Experiments on the foams with the density of 1-2.3 mg/cm 3 , thickness of 100-200 μm, and the cells' sizes up to the tens of micrometers were carried out with the radiation wavelength of 0.657 μm. The RMS non-uniformity < 5% has been found for the beam passed through the foam. The non-uniformity is evenly distributed over the spatial frequency spectrum. The induced divergence of radiation is measured to be 0.35 radian. The frequency of the rearranged speckled field of about 2 THz was obtained. The beam smoothing was recorded from the start of pulse of radiation, had the duration up to 1 ns, and the width of the radiation spectrum was about 30 A. The work was performed in part under the sponsorship of the RFFI (grants No. 09-02-12157-ofi-m and No. 09-02-97095-r-povolzh'ye-a) and grant of the President of the RF to leading scientific schools No. 65192.2010.2.

  20. Whole-body voxel-based personalized dosimetry: Multiple voxel S-value approach for heterogeneous media with non-uniform activity distributions.

    Science.gov (United States)

    Lee, Min Sun; Kim, Joong Hyun; Paeng, Jin Chul; Kang, Keon Wook; Jeong, Jae Min; Lee, Dong Soo; Lee, Jae Sung

    2017-12-14

    Personalized dosimetry with high accuracy is becoming more important because of the growing interests in personalized medicine and targeted radionuclide therapy. Voxel-based dosimetry using dose point kernel or voxel S-value (VSV) convolution is available. However, these approaches do not consider medium heterogeneity. Here, we propose a new method for whole-body voxel-based personalized dosimetry for heterogeneous media with non-uniform activity distributions, which is referred to as the multiple VSV approach. Methods: The multiple numbers (N) of VSVs for media with different densities covering the whole-body density ranges were used instead of using only a single VSV for water. The VSVs were pre-calculated using GATE Monte Carlo simulation; those were convoluted with the time-integrated activity to generate density-specific dose maps. Computed tomography-based segmentation was conducted to generate binary maps for each density region. The final dose map was acquired by the summation of N segmented density-specific dose maps. We tested several sets of VSVs with different densities: N = 1 (single water VSV), 4, 6, 8, 10, and 20. To validate the proposed method, phantom and patient studies were conducted and compared with direct Monte Carlo, which was considered the ground truth. Finally, patient dosimetry (10 subjects) was conducted using the multiple VSV approach and compared with the single VSV and organ-based dosimetry approaches. Errors at the voxel- and organ-levels were reported for eight organs. Results: In the phantom and patient studies, the multiple VSV approach showed significant improvements regarding voxel-level errors, especially for the lung and bone regions. As N increased, voxel-level errors decreased, although some overestimations were observed at lung boundaries. In the case of multiple VSVs ( N = 8), we achieved voxel-level errors of 2.06%. In the dosimetry study, our proposed method showed much improved results compared to the single VSV and

  1. Formation and distribution of large lithologic-stratigraphic oil & gas fields (provinces

    Directory of Open Access Journals (Sweden)

    Shizhen Tao

    2018-02-01

    Full Text Available Since the “Tenth Five-Year Plan”, lithologic and stratigraphic reservoirs have been the main contribution of both the discovery as well as reserve and production increase in China; there were about 80% of proven reserves. The typical reservoirs in six major basins in the eastern, central, and western China were adopted as reservoir forming models. The reservoir forming models in three types of slopes, three types of depressions, and three types of lithologic reservoir assemblages have been built on the basis of application of new technologies, physical modeling of reservoir forming mechanism, and investigation to the formation and distribution of the reservoirs. The evaluation methods for large lithologic reservoirs provinces were established based on the forming mechanism and main controlling factors mentioned above. In addition, the study reveals the main controlling factors and the laws of enrichment of two types of stratigraphic reservoirs (pinch-out and weathered karst reservoirs based on the evaluation methods for large stratigraphic reservoir provinces that have been established. By comprehensively understanding the laws of enrichment of lithologic-stratigraphic reservoirs in four types of basins, specific evaluation methods and fine exploration techniques have been developed. The findings led to an exploration direction in the “Thirteenth Five-Year Plan” period. The study supported the exploration and selection of oil and gas plays, as well as promoted the exploration of lithologic and stratigraphic reservoirs. Keywords: Lithologic trap, Stratigraphic trap, Lithostratigraphic reservoir, Large oil and gas field, Large oil and gas province, Formation and distribution, Exploration potential

  2. Distribution of elements in human spinal cord

    International Nuclear Information System (INIS)

    Yukawa, Masae; Kobayashi, T.; Qiu, Y.; Kameda, N.; Ito, Y.; Otomo, E.

    1992-01-01

    The distribution of elements in human spinal cord was investigated on unfixed frozen cord material using PIXE technique. Distribution of Cu, Zn and Fe were not uniform in the cross section of the spinal cord and concentrations of these elements were higher in the anterior gray horn than in the other areas, while K and Cl distributed uniformly. The content of K changed along the spinal cord from the cervical to the lumbar level. These findings are discussed in relation to current understanding of the physiology of the spinal cord. (author)

  3. Experimental and Numerical Characterization of a Pulsed Supersonic Uniform Flow for Kinetics and Spectroscopy

    Science.gov (United States)

    Suas-David, Nicolas; Thawoos, Shameemah; Broderick, Bernadette M.; Suits, Arthur

    2017-06-01

    The current CPUF (Chirped Pulse Uniform Flow) and the new UF-CRDS (Uniform Flow Cavity Ring-Down Spectroscopy) setups relie mostly on the production of a good quality supersonic uniform flow. A supersonic uniform flow is produced by expanding a gas through a Laval nozzle - similar to the nozzles used in aeronautics - linked to a vacuum chamber. The expansion is characterized by an isentropic core where constant very low kinetic temperature (down to 20K) and constant density are observed. The relatively large diameter of the isentropic core associated with homogeneous thermodynamic conditions makes it a relevant tool for low temperature spectroscopy. On the other hand, the length along the axis of the flow of this core (could be longer than 50cm) allows kinetic studies which is one of the main interest of this setup (CRESU technique. The formation of a uniform flow requires an extreme accuracy in the design of the shape of the nozzle for a set of defined temperature/density. The design is based on a Matlab program which retrieves the shape of the isentropic core according to the method of characteristics prior to calculate the thickness of the boundary layer. Two different approaches are used to test the viability of a new nozzle derived from the program. First, a computational fluid dynamic software (OpenFOAM) models the distribution of the thermodynamic properties of the expansion. Then, fabricated nozzles using 3-D printing are tested based on Pitot measurements and spectroscopic analyses. I will present comparisons of simulation and measured performance for a range of nozzles. We will see how the high level of accuracy of numerical simulations provides a deeper knowledge of the experimental conditions. J. M. Oldham, C. Abeysekera, J. Joalland, L. N. Zack, K. Prozument, I. R. Sims, G. Barrat Park, R. W. Filed and A. G. Suits, J. Chem. Phys. 141, 154202, (2014). I. Sims, J. L. Queffelec, A. Defrance, C. Rebrion-Rowe, D. Travers, P. Bocherel, B. Rowe, I. W. Smith

  4. Geometagenomics illuminates the impact of agriculture on the distribution and prevalence of plant viruses at the ecosystem scale

    OpenAIRE

    Bernardo, Pauline; Charles-Dominique, Tristan; Barakat, Mohamed; Ortet, Philippe; Fernandez, Emmanuel; Filloux, Denis; Hartnady, Penelope; Rebelo, Tony A; Cousins, Stephen R; Mesleard, François; Cohez, Damien; Yavercovski, Nicole; Varsani, Arvind; Harkins, Gordon W; Peterschmitt, Michel

    2017-01-01

    Disease emergence events regularly result from human activities such as agriculture, which frequently brings large populations of genetically uniform hosts into contact with potential pathogens. Although viruses cause nearly 50% of emerging plant diseases, there is little systematic information about virus distribution across agro-ecological interfaces and large gaps in understanding of virus diversity in nature. Here we applied a novel landscape-scale geometagenomics approach to examine rela...

  5. Geometagenomics illuminates the impact of agriculture on the distribution and prevalence of plant viruses at the ecosystem scale

    OpenAIRE

    Bernardo, Pauline; Charles-Dominique, Tristan; Barakat, Mohamed; Ortet, Philippe; Fernandez, Emmanuel; Filloux, Denis; Hartnady, Penelope; Rebelo, Tony A.; Cousins, Stephen; Mesleard, François; Cohez, Damien; Yaverkovski, Nicole; Varsani, Arvind; Harkins, Gordon William; Peterschmitt, Michel

    2018-01-01

    Disease emergence events regularly result from human activities such as agriculture, which frequently brings large populations of genetically uniform hosts into contact with potential pathogens. Although viruses cause nearly 50% of emerging plant diseases, there is little systematic information about virus distribution across agro-ecological interfaces and large gaps in understanding of virus diversity in nature. Here we applied a novel landscape-scale geometagenomics approach to examine rela...

  6. A theoretical bilevel control scheme for power networks with large-scale penetration of distributed renewable resources

    DEFF Research Database (Denmark)

    Boroojeni, Kianoosh; Amini, M. Hadi; Nejadpak, Arash

    2016-01-01

    In this paper, we present a bilevel control framework to achieve a highly-reliable smart distribution network with large-scale penetration of distributed renewable resources (DRRs). We assume that the power distribution network consists of several residential/commercial communities. In the first ...

  7. Experimental demonstration of a tailored-width microchannel heat exchanger configuration for uniform wall temperature

    International Nuclear Information System (INIS)

    Riera, S; Barrau, J; Rosell, J I; Omri, M; Fréchette, L G

    2013-01-01

    In this work, an experimental study of a novel microfabricated heat sink configuration that tends to uniform the wall temperature, even with increasing flow temperature, is presented. The design consists of a series of microchannel sections with stepwise varying width. This scheme counteracts the flow temperature increase by reducing the local thermal resistance along the flow path. A test apparatus with uniform heat flux and distributed wall temperature measurements was developed for microchannel heat exchanger characterisation. The energy balance is checked and the temperature distribution is analysed for each test. The results show that the wall temperature decreases slightly along the flow path while the fluid temperature increases, highlighting the strong impact of this approach. For a flow rate of 16 ml/s, the mean thermal resistance of the heat sink is 2,35·10 −5 m 2 ·K/W which enhances the results compared to the millimeter scale channels nearly three-fold. For the same flow rate and a heat flux of 50 W/cm 2 , the temperature uniformity, expressed as the standard deviation of the wall temperature, is around 6 °C

  8. Additive non-uniform random sampling in superimposed fiber Bragg grating strain gauge

    International Nuclear Information System (INIS)

    Ma, Y C; Liu, H Y; Yan, S B; Li, J M; Tang, J; Yang, Y H; Yang, M W

    2013-01-01

    This paper demonstrates an additive non-uniform random sampling and interrogation method for dynamic and/or static strain gauge using a reflection spectrum from two superimposed fiber Bragg gratings (FBGs). The superimposed FBGs are designed to generate non-equidistant space of a sensing pulse train in the time domain during dynamic strain gauge. By combining centroid finding with smooth filtering methods, both the interrogation speed and accuracy are improved. A 1.9 kHz dynamic strain is measured by generating an additive non-uniform randomly distributed 2 kHz optical sensing pulse train from a mean 500 Hz triangular periodically changing scanning frequency. (paper)

  9. Distribution, Statistics, and Resurfacing of Large Impact Basins on Mercury

    Science.gov (United States)

    Fassett, Caleb I.; Head, James W.; Baker, David M. H.; Chapman, Clark R.; Murchie, Scott L.; Neumann, Gregory A.; Oberst, Juergen; Prockter, Louise M.; Smith, David E.; Solomon, Sean C.; hide

    2012-01-01

    The distribution and geological history of large impact basins (diameter D greater than or equal to 300 km) on Mercury is important to understanding the planet's stratigraphy and surface evolution. It is also informative to compare the density of impact basins on Mercury with that of the Moon to understand similarities and differences in their impact crater and basin populations [1, 2]. A variety of impact basins were proposed on the basis of geological mapping with Mariner 10 data [e.g. 3]. This basin population can now be re-assessed and extended to the full planet, using data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. Note that small-to- medium-sized peak-ring basins on Mercury are being examined separately [4, 5]; only the three largest peak-ring basins on Mercury overlap with the size range we consider here. In this study, we (1) re-examine the large basins suggested on the basis of Mariner 10 data, (2) suggest additional basins from MESSENGER's global coverage of Mercury, (3) assess the size-frequency distribution of mercurian basins on the basis of these global observations and compare it to the Moon, and (4) analyze the implications of these observations for the modification history of basins on Mercury.

  10. Non-uniform approximations for sums of discrete m-dependent random variables

    OpenAIRE

    Vellaisamy, P.; Cekanavicius, V.

    2013-01-01

    Non-uniform estimates are obtained for Poisson, compound Poisson, translated Poisson, negative binomial and binomial approximations to sums of of m-dependent integer-valued random variables. Estimates for Wasserstein metric also follow easily from our results. The results are then exemplified by the approximation of Poisson binomial distribution, 2-runs and $m$-dependent $(k_1,k_2)$-events.

  11. Devaney's chaos on uniform limit maps

    International Nuclear Information System (INIS)

    Yan Kesong; Zeng Fanping; Zhang Gengrong

    2011-01-01

    Highlights: → The transitivity may not been inherited even if the sequence functions mixing. → The sensitivity may not been inherited even if the iterates of sequence have some uniform convergence. → Some equivalence conditions for the transitivity and sensitivity for uniform limit function are given. → A non-transitive sequence may converge uniformly to a transitive map. - Abstract: Let (X, d) be a compact metric space and f n : X → X a sequence of continuous maps such that (f n ) converges uniformly to a map f. The purpose of this paper is to study the Devaney's chaos on the uniform limit f. On the one hand, we show that f is not necessarily transitive even if all f n mixing, and the sensitive dependence on initial conditions may not been inherited to f even if the iterates of the sequence have some uniform convergence, which correct two wrong claims in . On the other hand, we give some equivalence conditions for the uniform limit f to be transitive and to have sensitive dependence on initial conditions. Moreover, we present an example to show that a non-transitive sequence may converge uniformly to a transitive map.

  12. Differential distribution of inflammatory cells in large and small airways in smokers

    NARCIS (Netherlands)

    Battaglia, Salvatore; Mauad, Thais; van Schadewijk, Annemarie M.; Vignola, Antonia M.; Rabe, Klaus F.; Bellia, Vincenzo; Sterk, Peter J.; Hiemstra, Pieter S.

    2007-01-01

    BACKGROUND: Smoking induces structural changes in the airways, and is considered a major factor in the development of airflow obstruction in chronic obstructive pulmonary disease. However, differences in inflammatory cell distribution between large airways (LA) and small airways (SA) have not been

  13. A simple approximation to the bivariate normal distribution with large correlation coefficient

    NARCIS (Netherlands)

    Albers, Willem/Wim; Kallenberg, W.C.M.

    1994-01-01

    The bivariate normal distribution function is approximated with emphasis on situations where the correlation coefficient is large. The high accuracy of the approximation is illustrated by numerical examples. Moreover, exact upper and lower bounds are presented as well as asymptotic results on the

  14. A Matrix-Based Proactive Data Relay Algorithm for Large Distributed Sensor Networks

    Directory of Open Access Journals (Sweden)

    Yang Xu

    2016-08-01

    Full Text Available In large-scale distributed sensor networks, sensed data is required to be relayed around the network so that one or few sensors can gather adequate relative data to produce high quality information for decision-making. In regards to very high energy-constraint sensor nodes, data transmission should be extremely economical. However, traditional data delivery protocols are potentially inefficient relaying unpredictable sensor readings for data fusion in large distributed networks for either overwhelming query transmissions or unnecessary data coverage. By building sensors’ local model from their previously transmitted data in three matrixes, we have developed a novel energy-saving data relay algorithm, which allows sensors to proactively make broadcast decisions by using a neat matrix computation to provide balance between transmission and energy-saving. In addition, we designed a heuristic maintenance algorithm to efficiently update these three matrices. This can easily be deployed to large-scale mobile networks in which decisions of sensors are based on their local matrix models no matter how large the network is, and the local models of these sensors are updated constantly. Compared with some traditional approaches based on our simulations, the efficiency of this approach is manifested in uncertain environment. The results show that our approach is scalable and can effectively balance aggregating data with minimizing energy consumption.

  15. Bridge density functional approximation for non-uniform hard core repulsive Yukawa fluid

    International Nuclear Information System (INIS)

    Zhou Shiqi

    2008-01-01

    In this work, a bridge density functional approximation (BDFA) (J. Chem. Phys. 112, 8079 (2000)) for a non-uniform hard-sphere fluid is extended to a non-uniform hard-core repulsive Yukawa (HCRY) fluid. It is found that the choice of a bulk bridge functional approximation is crucial for both a uniform HCRY fluid and a non-uniform HCRY fluid. A new bridge functional approximation is proposed, which can accurately predict the radial distribution function of the bulk HCRY fluid. With the new bridge functional approximation and its associated bulk second order direct correlation function as input, the BDFA can be used to well calculate the density profile of the HCRY fluid subjected to the influence of varying external fields, and the theoretical predictions are in good agreement with the corresponding simulation data. The calculated results indicate that the present BDFA captures quantitatively the phenomena such as the coexistence of solid-like high density phase and low density gas phase, and the adsorption properties of the HCRY fluid, which qualitatively differ from those of the fluids combining both hard-core repulsion and an attractive tail. (condensed matter: structure, thermal and mechanical properties)

  16. Experience in treatment of the radiation syndrome in accident victims exposed with non-uniform distribution of the dose within a body

    International Nuclear Information System (INIS)

    Guskova, A.; Barabanova, A

    1996-01-01

    Experience in diagnosis and treatment of radiation accident victims undergone to radiation expose with non-uniform distribution of the dose within a body is presented and the most significant features of medical management of such patients are discussed. The term 'compound radiation injure' is proposed to use for this form of radiation disease. Treatment of compound radiation injure demands a participation of very qualified specialists. The first medical aid and management should include careful body surface monitoring. Beside daily haematological observation and cytogenetic study with corresponding treatment, careful observation and registration of skin reaction are necessary. Some features of treatment are the following: more early administration of anti infection means, including isolation in sterile room, timely surgical intervention, prophylacsis and treatment of endorganic intoxication improving of microcirculation, long time follow up study with pathogenic therapy. (author)

  17. Realization of high irradiation uniformity for direct drive ICF at the SG-III prototype laser facility

    International Nuclear Information System (INIS)

    Tian, C.; Shan, L.; Zhang, B.; Zhou, W.; Liu, D.; Bi, B.; Zhang, F.; Wang, W.; Zhang, B.; Giu, Y.

    2015-01-01

    The direct drive irradiation uniformity during the initial imprinting phase at the SG-III prototype laser facility is analyzed and optimized with different methods. At first, the polar direct drive technique is applied to reduce the root mean square deviation σ from 16.1% to 6.4%. To further reduce the non-uniformity, we propose a new method by adjusting the intensity distribution of the laser spot. The overlap of laser beams on the capsule surface is studied and a factor is introduced to adjust the intensity of the laser spot for achieving absolute irradiation uniformity while bringing wild intensity change at laser spot edges. Noting that the overlapping region at the capsule surface is symmetrically distributed, the contribution of light from the edge of a spot can be transferred to its own internal. The newly adjusted intensity distributes at two main regions and the intensity varies slowly and continuously in each, further reducing σ to about 0.35%. Taken into account that the adjusted intensity has very sharp steps, super-Gaussian spatial profiles are used to approximate the required intensity to make it more practicable, which leads σ to 0.94%. Furthermore, sensitivity analysis to beam errors is performed and results show that this scheme can tolerate a certain amount of uncertainties. (authors)

  18. A Parallel Distributed-Memory Particle Method Enables Acquisition-Rate Segmentation of Large Fluorescence Microscopy Images

    Science.gov (United States)

    Afshar, Yaser; Sbalzarini, Ivo F.

    2016-01-01

    Modern fluorescence microscopy modalities, such as light-sheet microscopy, are capable of acquiring large three-dimensional images at high data rate. This creates a bottleneck in computational processing and analysis of the acquired images, as the rate of acquisition outpaces the speed of processing. Moreover, images can be so large that they do not fit the main memory of a single computer. We address both issues by developing a distributed parallel algorithm for segmentation of large fluorescence microscopy images. The method is based on the versatile Discrete Region Competition algorithm, which has previously proven useful in microscopy image segmentation. The present distributed implementation decomposes the input image into smaller sub-images that are distributed across multiple computers. Using network communication, the computers orchestrate the collectively solving of the global segmentation problem. This not only enables segmentation of large images (we test images of up to 1010 pixels), but also accelerates segmentation to match the time scale of image acquisition. Such acquisition-rate image segmentation is a prerequisite for the smart microscopes of the future and enables online data compression and interactive experiments. PMID:27046144

  19. A Parallel Distributed-Memory Particle Method Enables Acquisition-Rate Segmentation of Large Fluorescence Microscopy Images.

    Directory of Open Access Journals (Sweden)

    Yaser Afshar

    Full Text Available Modern fluorescence microscopy modalities, such as light-sheet microscopy, are capable of acquiring large three-dimensional images at high data rate. This creates a bottleneck in computational processing and analysis of the acquired images, as the rate of acquisition outpaces the speed of processing. Moreover, images can be so large that they do not fit the main memory of a single computer. We address both issues by developing a distributed parallel algorithm for segmentation of large fluorescence microscopy images. The method is based on the versatile Discrete Region Competition algorithm, which has previously proven useful in microscopy image segmentation. The present distributed implementation decomposes the input image into smaller sub-images that are distributed across multiple computers. Using network communication, the computers orchestrate the collectively solving of the global segmentation problem. This not only enables segmentation of large images (we test images of up to 10(10 pixels, but also accelerates segmentation to match the time scale of image acquisition. Such acquisition-rate image segmentation is a prerequisite for the smart microscopes of the future and enables online data compression and interactive experiments.

  20. A survey and experimental comparison of distributed SPARQL engines for very large RDF data

    KAUST Repository

    Abdelaziz, Ibrahim; Harbi, Razen; Khayyat, Zuhair; Kalnis, Panos

    2017-01-01

    Distributed SPARQL engines promise to support very large RDF datasets by utilizing shared-nothing computer clusters. Some are based on distributed frameworks such as MapReduce; others implement proprietary distributed processing; and some rely on expensive preprocessing for data partitioning. These systems exhibit a variety of trade-offs that are not well-understood, due to the lack of any comprehensive quantitative and qualitative evaluation. In this paper, we present a survey of 22 state-of-the-art systems that cover the entire spectrum of distributed RDF data processing and categorize them by several characteristics. Then, we select 12 representative systems and perform extensive experimental evaluation with respect to preprocessing cost, query performance, scalability and workload adaptability, using a variety of synthetic and real large datasets with up to 4.3 billion triples. Our results provide valuable insights for practitioners to understand the trade-offs for their usage scenarios. Finally, we publish online our evaluation framework, including all datasets and workloads, for researchers to compare their novel systems against the existing ones.

  1. A survey and experimental comparison of distributed SPARQL engines for very large RDF data

    KAUST Repository

    Abdelaziz, Ibrahim

    2017-10-19

    Distributed SPARQL engines promise to support very large RDF datasets by utilizing shared-nothing computer clusters. Some are based on distributed frameworks such as MapReduce; others implement proprietary distributed processing; and some rely on expensive preprocessing for data partitioning. These systems exhibit a variety of trade-offs that are not well-understood, due to the lack of any comprehensive quantitative and qualitative evaluation. In this paper, we present a survey of 22 state-of-the-art systems that cover the entire spectrum of distributed RDF data processing and categorize them by several characteristics. Then, we select 12 representative systems and perform extensive experimental evaluation with respect to preprocessing cost, query performance, scalability and workload adaptability, using a variety of synthetic and real large datasets with up to 4.3 billion triples. Our results provide valuable insights for practitioners to understand the trade-offs for their usage scenarios. Finally, we publish online our evaluation framework, including all datasets and workloads, for researchers to compare their novel systems against the existing ones.

  2. A Local Scalable Distributed Expectation Maximization Algorithm for Large Peer-to-Peer Networks

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper describes a local and distributed expectation maximization algorithm for learning parameters of Gaussian mixture models (GMM) in large peer-to-peer (P2P)...

  3. Many-junction photovoltaic device performance under non-uniform high-concentration illumination

    Science.gov (United States)

    Valdivia, Christopher E.; Wilkins, Matthew M.; Chahal, Sanmeet S.; Proulx, Francine; Provost, Philippe-Olivier; Masson, Denis P.; Fafard, Simon; Hinzer, Karin

    2017-09-01

    A parameterized 3D distributed circuit model was developed to calculate the performance of III-V solar cells and photonic power converters (PPC) with a variable number of epitaxial vertically-stacked pn junctions. PPC devices are designed with many pn junctions to realize higher voltages and to operate under non-uniform illumination profiles from a laser or LED. Performance impacts of non-uniform illumination were greatly reduced with increasing number of junctions, with simulations comparing PPC devices with 3 to 20 junctions. Experimental results using Azastra Opto's 12- and 20-junction PPC illuminated by an 845 nm diode laser show high performance even with a small gap between the PPC and optical fiber output, until the local tunnel junction limit is reached.

  4. High voltage distribution scheme for large size GEM detector

    International Nuclear Information System (INIS)

    Saini, J.; Kumar, A.; Dubey, A.K.; Negi, V.S.; Chattopadhyay, S.

    2016-01-01

    Gas Electron Multiplier (GEM) detectors will be used for Muon tracking in the Compressed Baryonic Matter (CBM) experiment at the Facility for Anti-proton Ion Research (FAIR) at Darmstadt, Germany. The sizes of the detector modules in the Muon chambers are of the order of 1 metre x 0.5 metre. For construction of these chambers, three GEM foils are used per chamber. These foils are made by two layered 50μm thin kapton foil. Each GEM foil has millions of holes on it. In such a large scale manufacturing of the foils, even after stringent quality controls, some of the holes may still have defects or defects might develop over the time with operating conditions. These defects may result in short-circuit of the entire GEM foil. A short even in a single hole will make entire foil un-usable. To reduce such occurrences, high voltage (HV) segmentation within the foils has been introduced. These segments are powered either by individual HV supply per segment or through an active HV distribution to manage such a large number of segments across the foil. Individual supplies apart from being costly, are highly complex to implement. Additionally, CBM will have high intensity of particles bombarding on the detector causing the change of resistive chain current feeding the GEM detector with the variation in the intensity. This leads to voltage fluctuations across the foil resulting in the gain variation with the particle intensity. Hence, a low cost active HV distribution is designed to take care of the above discussed issues

  5. Effect of bed configuration on pebble flow uniformity and stagnation in the pebble bed reactor

    International Nuclear Information System (INIS)

    Gui, Nan; Yang, Xingtuan; Tu, Jiyuan; Jiang, Shengyao

    2014-01-01

    Highlights: • Pebble flow uniformity and stagnation characteristics are very important for HTR-PM. • Arc- and brachistochrone-shaped configuration effects are studied by DEM simulation. • Best bed configurations with uniform flow and no stagnated pebbles are suggested. • Detailed quantified characteristics of bed configuration effects are shown for explanation. - Abstract: Pebble flow uniformity and stagnation characteristics are very important for the design of pebble bed high temperature gas-cooled reactor. Pebble flows inside some specifically designed contraction configurations of pebble bed are studied by discrete element method. The results show the characteristics of stagnation rates, recycling rates, radial distribution of pebble velocity and residence time. It is demonstrated clearly that the bed with a brachistochrone-shaped configuration achieves optimum levels of flow uniformity and recycling rate concentration, and almost no pebbles are stagnated in the bed. Moreover, the optimum choice among the arc-shaped bed configurations is demonstrated too. Detailed information shows the quantified characteristics of bed configuration effects on flow uniformity. In addition, a good design of the pebble bed configuration is suggested

  6. SPINS OF LARGE ASTEROIDS: A HINT OF A PRIMORDIAL DISTRIBUTION IN THEIR SPIN RATES

    Energy Technology Data Exchange (ETDEWEB)

    Steinberg, Elad; Sari, Re’em [The Hebrew University of Jerusalem, Jerusalem (Israel)

    2015-04-15

    The Asteroid Belt and the Kuiper Belt are relics from the formation of our solar system. Understanding the size and spin distribution of the two belts is crucial for a deeper understanding of the formation of our solar system and the dynamical processes that govern it. In this paper, we investigate the effect of collisions on the evolution of the spin distribution of asteroids and KBOs. We find that the power law nature of the impactors’ size distribution leads to a Lévy distribution of the spin rates. This results in a power law tail in the spin distribution, in stark contrast to the usually quoted Maxwellian distribution. We show that for bodies larger than 10 km, collisions alone lead to spin rates peaking at 0.15–0.5 revolutions per day. Comparing that to the observed spin rates of large asteroids (R > 50 km), we find that the spins of large asteroids, peaking at ∼1–2 revolutions per day, are dominated by a primordial component that reflects the formation mechanism of the asteroids. Similarly, the Kuiper Belt has undergone virtually no collisional spin evolution, assuming current densities. Collisions contribute a spin rate of ∼0.01 revolutions per day, thus the observed fast spin rates of KBOs are also primordial in nature.

  7. Influence of carbon black distribution on performance of oxide cathodes for Li ion batteries

    International Nuclear Information System (INIS)

    Dominko, Robert; Gaberscek, Miran; Drofenik, Jernej; Bele, Marjan; Jamnik, Janez

    2003-01-01

    The influence of carbon black content and carbon black distribution on performance of oxide-based cathodes, such as LiCoO 2 and LiMn 2 O 4 , is investigated. The electronic conductivity of oxide material/carbon black composites is compared with electrochemical characteristics of the same composites. Uniformity of carbon black distribution in cathode composites is achieved using novel coating technology in cathode preparation. In this technology, the active particles are first pretreated in a gelatin solution. The adsorbed gelatin then controls the deposition of carbon black so that carbon black particles are uniformly distributed in the final composite. The influence of various parameters, such as pH of gelatin, amount of gelatin and concentration of carbon black on the uniformity of carbon black distribution is investigated. It is shown that the conventional technology of cathode preparation yields quite non-uniform distribution of carbon black in cathode material. At the end, we demonstrate that uniformity of carbon black distribution has a crucial impact on reversible capacity, especially at high current densities

  8. A Novel Approach of Using Ground CNTs as the Carbon Source to Fabricate Uniformly Distributed Nano-Sized TiCx/2009Al Composites.

    Science.gov (United States)

    Wang, Lei; Qiu, Feng; Ouyang, Licheng; Wang, Huiyuan; Zha, Min; Shu, Shili; Zhao, Qinglong; Jiang, Qichuan

    2015-12-17

    Nano-sized TiC x /2009Al composites (with 5, 7, and 9 vol% TiC x ) were fabricated via the combustion synthesis of the 2009Al-Ti-CNTs system combined with vacuum hot pressing followed by hot extrusion. In the present study, CNTs were used as the carbon source to synthesize nano-sized TiC x particles. An attempt was made to correlate the effect of ground CNTs by milling and the distribution of synthesized nano-sized TiC x particles in 2009Al as well as the tensile properties of nano-sized TiC x /2009Al composites. Microstructure analysis showed that when ground CNTs were used, the synthesized nano-sized TiC x particles dispersed more uniformly in the 2009Al matrix. Moreover, when 2 h-milled CNTs were used, the 5, 7, and 9 vol% nano-sized TiC x /2009Al composites had the highest tensile properties, especially, the 9 vol% nano-sized TiC x /2009Al composites. The results offered a new approach to improve the distribution of in situ nano-sized TiC x particles and tensile properties of composites.

  9. Template-free formation of vertically oriented TiO2 nanorods with uniform distribution for organics-sensing application

    International Nuclear Information System (INIS)

    Mu Qinghui; Li Yaogang; Zhang Qinghong; Wang Hongzhi

    2011-01-01

    Graphical abstract: - Abstract: High-density arrays of vertically oriented TiO 2 nanorods with uniform distribution on Ti foil have been formed through template-free oxidation of Ti in hydrogen peroxide solutions. Subsequent thermal treatment was applied for growing mixed crystal structures to pursue higher performance. Morphology characterization using field emission scanning electron microscopy (FESEM) shows a nanorod diameter in the range of 20-50 nm with a length of 1.5 μm. X-ray diffraction (XRD) measurement demonstrates the crystallization of the TiO 2 nanorods prior to thermal treatment and the formation of anatase and rutile mixed phase after thermal treatment. The mixed crystal TiO 2 nanorods show a much higher performance than pure anatase in photoelectrochemical experiments. Steady-state photocurrent resulted from photocatalytic oxidation of organic compounds by TiO 2 nanorods is employed as response signal in determination of the organics to yield a linear range of 0-1.1 mM for glucose. For other organics, an excellent linear relationship between the net steady-state photocurrent and the concentration of electrons transferred in exhaustive oxidation for these organics is obtained, which empowers the mixed crystal TiO 2 nanorods to serve as versatile material in organics-sensing application.

  10. Photoionization microscopy of Rydberg hydrogen atom in a non-uniform electrical field

    International Nuclear Information System (INIS)

    Cheng Shao-Hao; Wang De-Hua; Chen Zhao-Hang; Chen Qiang

    2016-01-01

    In this paper, we investigate the photoionization microscopy of the Rydberg hydrogen atom in a gradient electric field for the first time. The observed oscillatory patterns in the photoionization microscopy are explained within the framework of the semiclassical theory, which can be considered as a manifestation of interference between various electron trajectories arriving at a given point on the detector plane. In contrast with the photoionization microscopy in the uniform electric field, the trajectories of the ionized electron in the gradient electric field will become chaotic. An infinite set of different electron trajectories can arrive at a given point on the detector plane, which makes the interference pattern of the electron probability density distribution extremely complicated. Our calculation results suggest that the oscillatory pattern in the electron probability density distribution depends sensitively on the electric field gradient, the scaled energy and the position of the detector plane. Through our research, we predict that the interference pattern in the electron probability density distribution can be observed in an actual photoionization microscopy experiment once the external electric field strength and the position of the electron detector plane are reasonable. This study provides some references for the future experimental research on the photoionization microscopy of the Rydberg atom in the non-uniform external fields. (paper)

  11. Formation process of graphite film on Ni substrate with improved thickness uniformity through precipitation control

    Science.gov (United States)

    Kim, Seul-Gi; Hu, Qicheng; Nam, Ki-Bong; Kim, Mun Ja; Yoo, Ji-Beom

    2018-04-01

    Large-scale graphitic thin film with high thickness uniformity needs to be developed for industrial applications. Graphitic films with thicknesses ranging from 3 to 20 nm have rarely been reported, and achieving the thickness uniformity in that range is a challenging task. In this study, a process for growing 20 nm-thick graphite films on Ni with improved thickness uniformity is demonstrated and compared with the conventional growth process. In the film grown by the process, the surface roughness and coverage were improved and no wrinkles were observed. Observations of the film structure reveal the reasons for the improvements and growth mechanisms.

  12. Staghorn: An Automated Large-Scale Distributed System Analysis Platform

    Energy Technology Data Exchange (ETDEWEB)

    Gabert, Kasimir [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Burns, Ian [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Elliott, Steven [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kallaher, Jenna [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Vail, Adam [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-09-01

    Conducting experiments on large-scale distributed computing systems is becoming significantly easier with the assistance of emulation. Researchers can now create a model of a distributed computing environment and then generate a virtual, laboratory copy of the entire system composed of potentially thousands of virtual machines, switches, and software. The use of real software, running at clock rate in full virtual machines, allows experiments to produce meaningful results without necessitating a full understanding of all model components. However, the ability to inspect and modify elements within these models is bound by the limitation that such modifications must compete with the model, either running in or alongside it. This inhibits entire classes of analyses from being conducted upon these models. We developed a mechanism to snapshot an entire emulation-based model as it is running. This allows us to \\freeze time" and subsequently fork execution, replay execution, modify arbitrary parts of the model, or deeply explore the model. This snapshot includes capturing packets in transit and other input/output state along with the running virtual machines. We were able to build this system in Linux using Open vSwitch and Kernel Virtual Machines on top of Sandia's emulation platform Firewheel. This primitive opens the door to numerous subsequent analyses on models, including state space exploration, debugging distributed systems, performance optimizations, improved training environments, and improved experiment repeatability.

  13. Evaluation of the dose uniformity for double-plane high dose rate interstitial breast implants with the use of dose reference points and dose non-uniformity ratio

    International Nuclear Information System (INIS)

    MAjor, T.; Polgar, C.; Somogyi, A.; Nemeth, G.

    2000-01-01

    also the high dose volume. The optimization on dose points and geometry provides the most uniform dose distribution. The dose non-uniformity ratio can be minimized by selecting the isodose line of the midpoints between the catheters in the whole volume for the dose prescription, but the dose coverage may not be adequate. For a clinically acceptable plan, a compromise should be made between dose non-uniformity and coverage. (author)

  14. Transient critical heat flux under flow coast-down in vertical annulus with non-uniform heat flux distribution

    International Nuclear Information System (INIS)

    Moon, S.K.; Chun, S.Y.; Choi, K.Y.; Yang, S.K.

    2001-01-01

    An experimental study on transient critical heat flux (CHF) under flow coast-down has been performed for water flow in a non-uniformly heated vertical annulus under low flow and a wide range of pressure conditions. The objectives of this study are to systematically investigate the effect of the flow transient on the CHF and to compare the transient CHF with steady state CHF. The transient CHF experiments have been performed for three kinds of flow transient modes based on the coast-down data of the Kori 3/4 nuclear power plant reactor coolant pump. Most of the CHFs occurred in the annular-mist flow regime. Thus, it means that the possible CHF mechanism might be the liquid film dryout in the annular-mist flow regime. For flow transient mode with the smallest flow reduction rate, the time-to-CHF is the largest. At the same inlet subcooling, system pressure and heat flux, the effect of the initial mass flux on the critical mass flux can be negligible. However, the effect of the initial mass flux on the time-to-CHF becomes large as the heat flux decreases. Usually, the critical mass flux is large for slow flow reduction. There is a pressure effect on the ratio of the transient CHF data to steady state CHF data. Some conventional correlations show relatively better CHF prediction results for high system pressure, high quality and slow transient modes than for low system pressure, low quality and fast transient modes. (author)

  15. School Uniforms. Research Brief

    Science.gov (United States)

    Walker, Karen

    2007-01-01

    Does clothing make the person or does the person make the clothing? How does what attire a student wears to school affect their academic achievement? In 1996, President Clinton cited examples of school violence and discipline issues that might have been avoided had the students been wearing uniforms ("School uniforms: Prevention or suppression?").…

  16. Statistical distribution of the local purity in a large quantum system

    International Nuclear Information System (INIS)

    De Pasquale, A; Pascazio, S; Facchi, P; Giovannetti, V; Parisi, G; Scardicchio, A

    2012-01-01

    The local purity of large many-body quantum systems can be studied by following a statistical mechanical approach based on a random matrix model. Restricting the analysis to the case of global pure states, this method proved to be successful, and a full characterization of the statistical properties of the local purity was obtained by computing the partition function of the problem. Here we generalize these techniques to the case of global mixed states. In this context, by uniformly sampling the phase space of states with assigned global mixedness, we determine the exact expression of the first two moments of the local purity and a general expression for the moments of higher order. This generalizes previous results obtained for globally pure configurations. Furthermore, through the introduction of a partition function for a suitable canonical ensemble, we compute the approximate expression of the first moment of the marginal purity in the high-temperature regime. In the process, we establish a formal connection with the theory of quantum twirling maps that provides an alternative, possibly fruitful, way of performing the calculation. (paper)

  17. Optimal distribution of temperature points in μSR measurement of local field

    International Nuclear Information System (INIS)

    Pełka, R.; Zieliński, P.M.; Konieczny, P.; Wasiutyński, T.

    2013-01-01

    Three possible distributions of temperature points in the μSR measurement of local field (order parameter) are discussed. The least square method is applied to estimate the scale of the deviations of the fitted parameters from the true values. It indicates that the distribution corresponding to a uniform section of the order parameter values (uniform-in-signal) incurs the smallest errors. The distribution constructed on the basis of the zeros of the Chebyshev polynomials yields comparable uncertainties, while the uniform-in-temperature distribution turns out to be least effective incurring considerably larger errors. These findings can be useful while planning an order parameter measurement in the μSR experiment

  18. Description of age, sex and site distribution of large bowel cancer in ...

    African Journals Online (AJOL)

    Aims/Objective: To determine the distribution of bowel cancer with special emphasis on age, sex and site. Methods: One hundred and sixty cases of histologically confirmed large bowel cancers at Jos University Teaching Hospital between January 1991 – December 2000 were reviewed. The records were collected from the ...

  19. Development of large-area silicon photomultiplier detectors for PET applications at FBK

    Energy Technology Data Exchange (ETDEWEB)

    Zorzi, Nicola, E-mail: zorzi@fbk.eu [Fondazione Bruno Kessler (FBK), Via Sommarive 18, I-38123 Trento Povo (Italy); Melchiorri, Mirko; Piazza, Alessandro; Piemonte, Claudio; Tarolli, Alessandro [Fondazione Bruno Kessler (FBK), Via Sommarive 18, I-38123 Trento Povo (Italy)

    2011-04-21

    This paper reports on the development of large-area silicon photomultiplier (SiPM) detectors specifically designed for positron emission tomography (PET) instruments. The sensors under study are monolithic arrays of two different types: a 2x2 array of {approx}4x4 mm{sup 2} elements and an 8x8 array of 1.5x1.5 mm{sup 2} pixels. These devices are characterized at wafer level by means of an automatic test procedure, consisting of current-voltage curves in forward and reverse bias. The tests allowed selection of functioning devices and evaluation of the uniformity of basic parameters. Results of the electrical characterization are reported showing that acceptable values of yield together with rather uniform distribution of parameters have been obtained. Reliability of produced SiPMs has been proved by long-term accelerated stress tests.

  20. Development of large-area silicon photomultiplier detectors for PET applications at FBK

    International Nuclear Information System (INIS)

    Zorzi, Nicola; Melchiorri, Mirko; Piazza, Alessandro; Piemonte, Claudio; Tarolli, Alessandro

    2011-01-01

    This paper reports on the development of large-area silicon photomultiplier (SiPM) detectors specifically designed for positron emission tomography (PET) instruments. The sensors under study are monolithic arrays of two different types: a 2x2 array of ∼4x4 mm 2 elements and an 8x8 array of 1.5x1.5 mm 2 pixels. These devices are characterized at wafer level by means of an automatic test procedure, consisting of current-voltage curves in forward and reverse bias. The tests allowed selection of functioning devices and evaluation of the uniformity of basic parameters. Results of the electrical characterization are reported showing that acceptable values of yield together with rather uniform distribution of parameters have been obtained. Reliability of produced SiPMs has been proved by long-term accelerated stress tests.

  1. TensorFlow: Large-Scale Machine Learning on Heterogeneous Distributed Systems

    OpenAIRE

    Abadi, Martín; Agarwal, Ashish; Barham, Paul; Brevdo, Eugene; Chen, Zhifeng; Citro, Craig; Corrado, Greg S.; Davis, Andy; Dean, Jeffrey; Devin, Matthieu; Ghemawat, Sanjay; Goodfellow, Ian; Harp, Andrew; Irving, Geoffrey; Isard, Michael

    2016-01-01

    TensorFlow is an interface for expressing machine learning algorithms, and an implementation for executing such algorithms. A computation expressed using TensorFlow can be executed with little or no change on a wide variety of heterogeneous systems, ranging from mobile devices such as phones and tablets up to large-scale distributed systems of hundreds of machines and thousands of computational devices such as GPU cards. The system is flexible and can be used to express a wide variety of algo...

  2. Theoretical Analysis of Unit Friction Force Working on the Metal Contact Surface with the Roll Change during Feedstock with Non-Uniform Temperature Distribution Rolling Process

    Directory of Open Access Journals (Sweden)

    Sygut P.

    2016-06-01

    Full Text Available The paper presents the results of theoretical studies influence of non-uniform temperature distribution along the feedstock length to the unit friction force working on the metal contact surface with the roll change during the round bars 70 mm in diameter continuous rolling process. This value is one of the major factors affecting the grooves wear during the rolling process. The studies were carried out based on the actual engineering data for 160 × 160 mm square cross-section feedstock of steel S355J0. Numerical modelling of the rolling process was performed using Forge2008®, a finite-element based computer program.

  3. Proceedings of the Workshop on Applications of Distributed System Theory to the Control of Large Space Structures

    Science.gov (United States)

    Rodriguez, G. (Editor)

    1983-01-01

    Two general themes in the control of large space structures are addressed: control theory for distributed parameter systems and distributed control for systems requiring spatially-distributed multipoint sensing and actuation. Topics include modeling and control, stabilization, and estimation and identification.

  4. Menzerath-Altmann law for distinct word distribution analysis in a large text

    Science.gov (United States)

    Eroglu, Sertac

    2013-06-01

    The empirical law uncovered by Menzerath and formulated by Altmann, known as the Menzerath-Altmann law (henceforth the MA law), reveals the statistical distribution behavior of human language in various organizational levels. Building on previous studies relating organizational regularities in a language, we propose that the distribution of distinct (or different) words in a large text can effectively be described by the MA law. The validity of the proposition is demonstrated by examining two text corpora written in different languages not belonging to the same language family (English and Turkish). The results show not only that distinct word distribution behavior can accurately be predicted by the MA law, but that this result appears to be language-independent. This result is important not only for quantitative linguistic studies, but also may have significance for other naturally occurring organizations that display analogous organizational behavior. We also deliberately demonstrate that the MA law is a special case of the probability function of the generalized gamma distribution.

  5. Effective electrodiffusion equation for non-uniform nanochannels.

    Science.gov (United States)

    Marini Bettolo Marconi, Umberto; Melchionna, Simone; Pagonabarraga, Ignacio

    2013-06-28

    We derive a one-dimensional formulation of the Planck-Nernst-Poisson equation to describe the dynamics of a symmetric binary electrolyte in channels whose section is nanometric and varies along the axial direction. The approach is in the spirit of the Fick-Jacobs diffusion equation and leads to a system of coupled equations for the partial densities which depends on the charge sitting at the walls in a non-trivial fashion. We consider two kinds of non-uniformities, those due to the spatial variation of charge distribution and those due to the shape variation of the pore and report one- and three-dimensional solutions of the electrokinetic equations.

  6. Flow distribution in the inlet plenum of steam generator

    International Nuclear Information System (INIS)

    Khadamakar, H.P.; Patwardhan, A.W.; Padmakumar, G.; Vaidyanathan, G.

    2011-01-01

    Highlights: → Various flow distribution devices have been studied to make the flow distribution uniform in axial as well as tangential direction. → Experiments were performed using Ultrasonic Velocity Profiler (UVP) and Particle Image Velocimetry (PIV). → CFD modeling has been carried out to give more insights. → Various flow distribution devices have been compared. - Abstract: The flow distribution in a 1/5th and 1/8th scale models of inlet plenum of steam generator (SG) has been studied by a combination of experiments and Computational Fluid Dynamics (CFD) simulations. The distribution of liquid sodium in the inlet plenum of the SG strongly affects the thermal as well as mechanical performance of the steam generator. Various flow distribution devices have been used to make the flow distribution uniform in axial as well as tangential direction in the window region. Experiments have been conducted to measure the radial velocity distribution using Ultrasonic Velocity Profiler (UVP) and Particle Image Velocimetry (PIV) under a variety of conditions. CFD modeling has been carried out for various configurations to give more insight into the flow distribution phenomena. The various flow distribution devices have been compared on the basis of a non-uniformity index parameter.

  7. The mathematical description of uniformity and related theorems

    International Nuclear Information System (INIS)

    Luo Chuanwen; Yi Chundi; Wang Gang; Li Longsuo; Wang Chuncheng

    2009-01-01

    Uniform index is a conception that can describe the uniformity of a finite point set in a polyhedron, and is closely related to chaos. In order to study uniform index, the concept of contained uniform index is defined, which is similar to uniform index and has good mathematical properties. In this paper, we prove the convergence of the contained uniform index, and develop the base of proving the convergence of uniform index.

  8. Bone-Marrow Stem-Cell Survival in the Non-Uniformly Exposed Mammal

    Energy Technology Data Exchange (ETDEWEB)

    Bond, V. P.; Robinson, C. V. [Brookhaven National Laboratory, Medical Research Center, Upton, Long Island, NY (United States)

    1967-07-15

    For comparison of the effectiveness of non-uniform versus uniform irradiations in causing haematological death in mammals, a model of the irradiated haemopoietic system has been proposed. The essential features of this model are: (1) that different parts of the haemopoietic system have numbers of stem cells which are proportioned to the amounts of active marrow in those parts as measured by {sup 59}Fe uptake, (2) that stem cells in the different parts are subject to the, same dose-survival relationship, and (3) that survival of the animal depends on survival of a critical fraction of the total number of stem cells independent of their distribution among the parts of the total marrow mass. To apply this model one needs to know: (a) the relative {sup 59}Fe uptakes of the different parts of the haemopoietic system, (b) the doses delivered to those parts by each of the exposures to be compared, and (c) the dose-survival curve applicable to the stem cells. From these one can calculate the fraction of stem cells surviving each exposure. In a preliminary communication the applicability of the model was investigated using data obtained entirely from the literature. Additional data, particularly on bone-marrow distribution, have since been obtained and are included here. The primary object of the present paper is to test further the validity of the above 'stem-cell survival model'. Data on bilateral (essentially uniform) versus unilateral and non-uniform rotational exposures in mammals are examined with respect to the surviving fraction of stem cells at the LD{sub 50/30} day dose level. Although an adequate test is not possible at present for lack of a full set of data in any one species, a partial test indicates compatibility with data for dogs and rats. Other possible mortality determinants such as doses or exposures at entrance, midline or exit, or the gram-rads or average dose to the marrow, appear to be less useful than the critical stem-cell survival fraction.

  9. Forbidden regimes in the distribution of bipartite quantum correlations due to multiparty entanglement

    Science.gov (United States)

    Kumar, Asutosh; Dhar, Himadri Shekhar; Prabhu, R.; Sen(De), Aditi; Sen, Ujjwal

    2017-05-01

    Monogamy is a nonclassical property that limits the distribution of quantum correlation among subparts of a multiparty system. We show that monogamy scores for different quantum correlation measures are bounded above by functions of genuine multipartite entanglement for a large majority of pure multiqubit states. The bound is universal for all three-qubit pure states. We derive necessary conditions to characterize the states that violate the bound, which can also be observed by numerical simulation for a small set of states, generated Haar uniformly. The results indicate that genuine multipartite entanglement restricts the distribution of bipartite quantum correlations in a multiparty system.

  10. A data science based standardized Gini index as a Lorenz dominance preserving measure of the inequality of distributions.

    Science.gov (United States)

    Ultsch, Alfred; Lötsch, Jörn

    2017-01-01

    The Gini index is a measure of the inequality of a distribution that can be derived from Lorenz curves. While commonly used in, e.g., economic research, it suffers from ambiguity via lack of Lorenz dominance preservation. Here, investigation of large sets of empirical distributions of incomes of the World's countries over several years indicated firstly, that the Gini indices are centered on a value of 33.33% corresponding to the Gini index of the uniform distribution and secondly, that the Lorenz curves of these distributions are consistent with Lorenz curves of log-normal distributions. This can be employed to provide a Lorenz dominance preserving equivalent of the Gini index. Therefore, a modified measure based on log-normal approximation and standardization of Lorenz curves is proposed. The so-called UGini index provides a meaningful and intuitive standardization on the uniform distribution as this characterizes societies that provide equal chances. The novel UGini index preserves Lorenz dominance. Analysis of the probability density distributions of the UGini index of the World's counties income data indicated multimodality in two independent data sets. Applying Bayesian statistics provided a data-based classification of the World's countries' income distributions. The UGini index can be re-transferred into the classical index to preserve comparability with previous research.

  11. A data science based standardized Gini index as a Lorenz dominance preserving measure of the inequality of distributions.

    Directory of Open Access Journals (Sweden)

    Alfred Ultsch

    Full Text Available The Gini index is a measure of the inequality of a distribution that can be derived from Lorenz curves. While commonly used in, e.g., economic research, it suffers from ambiguity via lack of Lorenz dominance preservation. Here, investigation of large sets of empirical distributions of incomes of the World's countries over several years indicated firstly, that the Gini indices are centered on a value of 33.33% corresponding to the Gini index of the uniform distribution and secondly, that the Lorenz curves of these distributions are consistent with Lorenz curves of log-normal distributions. This can be employed to provide a Lorenz dominance preserving equivalent of the Gini index. Therefore, a modified measure based on log-normal approximation and standardization of Lorenz curves is proposed. The so-called UGini index provides a meaningful and intuitive standardization on the uniform distribution as this characterizes societies that provide equal chances. The novel UGini index preserves Lorenz dominance. Analysis of the probability density distributions of the UGini index of the World's counties income data indicated multimodality in two independent data sets. Applying Bayesian statistics provided a data-based classification of the World's countries' income distributions. The UGini index can be re-transferred into the classical index to preserve comparability with previous research.

  12. Large Eddy Simulations of a Bottom Boundary Layer Under a Shallow Geostrophic Front

    Science.gov (United States)

    Bateman, S. P.; Simeonov, J.; Calantoni, J.

    2017-12-01

    The unstratified surf zone and the stratified shelf waters are often separated by dynamic fronts that can strongly impact the character of the Ekman bottom boundary layer. Here, we use large eddy simulations to study the turbulent bottom boundary layer associated with a geostrophic current on a stratified shelf of uniform depth. The simulations are initialized with a spatially uniform vertical shear that is in geostrophic balance with a pressure gradient due to a linear horizontal temperature variation. Superposed on the temperature front is a stable vertical temperature gradient. As turbulence develops near the bottom, the turbulence-induced mixing gradually erodes the initial uniform temperature stratification and a well-mixed layer grows in height until the turbulence becomes fully developed. The simulations provide the spatial distribution of the turbulent dissipation and the Reynolds stresses in the fully developed boundary layer. We vary the initial linear stratification and investigate its effect on the height of the bottom boundary layer and the turbulence statistics. The results are compared to previous models and simulations of stratified bottom Ekman layers.

  13. Uniform Gauss-Weight Quadratures for Discrete Ordinate Transport Calculations

    International Nuclear Information System (INIS)

    Carew, John F.; Hu, Kai; Zamonsky, Gabriel

    2000-01-01

    Recently, a uniform equal-weight quadrature set, UE n , and a uniform Gauss-weight quadrature set, UG n , have been derived. These quadratures have the advantage over the standard level-symmetric LQ n quadrature sets in that the weights are positive for all orders,and the transport solution may be systematically converged by increasing the order of the quadrature set. As the order of the quadrature is increased,the points approach a uniform continuous distribution on the unit sphere,and the quadrature is invariant with respect to spatial rotations. The numerical integrals converge for continuous functions as the order of the quadrature is increased.The numerical characteristics of the UE n quadrature set have been investigated previously. In this paper, numerical calculations are performed to evaluate the application of the UG n quadrature set in typical transport analyses. A series of DORT transport calculations of the >1-MeV neutron flux have been performed for a set of pressure-vessel fluence benchmark problems. These calculations employed the UG n (n = 8, 12, 16, 24, and 32) quadratures and indicate that the UG n solutions have converged to within ∼0.25%. The converged UG n solutions are found to be comparable to the UE n results and are more accurate than the level-symmetric S 16 predictions

  14. Large-scale geographic variation in distribution and abundance of Australian deep-water kelp forests.

    Directory of Open Access Journals (Sweden)

    Ezequiel M Marzinelli

    Full Text Available Despite the significance of marine habitat-forming organisms, little is known about their large-scale distribution and abundance in deeper waters, where they are difficult to access. Such information is necessary to develop sound conservation and management strategies. Kelps are main habitat-formers in temperate reefs worldwide; however, these habitats are highly sensitive to environmental change. The kelp Ecklonia radiate is the major habitat-forming organism on subtidal reefs in temperate Australia. Here, we provide large-scale ecological data encompassing the latitudinal distribution along the continent of these kelp forests, which is a necessary first step towards quantitative inferences about the effects of climatic change and other stressors on these valuable habitats. We used the Autonomous Underwater Vehicle (AUV facility of Australia's Integrated Marine Observing System (IMOS to survey 157,000 m2 of seabed, of which ca 13,000 m2 were used to quantify kelp covers at multiple spatial scales (10-100 m to 100-1,000 km and depths (15-60 m across several regions ca 2-6° latitude apart along the East and West coast of Australia. We investigated the large-scale geographic variation in distribution and abundance of deep-water kelp (>15 m depth and their relationships with physical variables. Kelp cover generally increased with latitude despite great variability at smaller spatial scales. Maximum depth of kelp occurrence was 40-50 m. Kelp latitudinal distribution along the continent was most strongly related to water temperature and substratum availability. This extensive survey data, coupled with ongoing AUV missions, will allow for the detection of long-term shifts in the distribution and abundance of habitat-forming kelp and the organisms they support on a continental scale, and provide information necessary for successful implementation and management of conservation reserves.

  15. Uniform Statistical Convergence on Time Scales

    Directory of Open Access Journals (Sweden)

    Yavuz Altin

    2014-01-01

    Full Text Available We will introduce the concept of m- and (λ,m-uniform density of a set and m- and (λ,m-uniform statistical convergence on an arbitrary time scale. However, we will define m-uniform Cauchy function on a time scale. Furthermore, some relations about these new notions are also obtained.

  16. Effects of fixture rotation on coating uniformity for high-performance optical filter fabrication

    Science.gov (United States)

    Rubin, Binyamin; George, Jason; Singhal, Riju

    2018-04-01

    Coating uniformity is critical in fabricating high-performance optical filters by various vacuum deposition methods. Simple and planetary rotation systems with shadow masks are used to achieve the required uniformity [J. B. Oliver and D. Talbot, Appl. Optics 45, 13, 3097 (2006); O. Lyngnes, K. Kraus, A. Ode and T. Erguder, in `Method for Designing Coating Thickness Uniformity Shadow Masks for Deposition Systems with a Planetary Fixture', 2014 Technical Conference Proceedings, Optical Coatings, August 13, 2014, DOI: 10.14332/svc14.proc.1817.]. In this work, we discuss the effect of rotation pattern and speed on thickness uniformity in an ion beam sputter deposition system. Numerical modeling is used to determine statistical distribution of random thickness errors in coating layers. The relationship between thickness tolerance and production yield are simulated theoretically and demonstrated experimentally. Production yields for different optical filters produced in an ion beam deposition system with planetary rotation are presented. Single-wavelength and broadband optical monitoring systems were used for endpoint monitoring during filter deposition. Limitations of thickness tolerances that can be achieved in systems with planetary rotation are shown. Paths for improving production yield in an ion beam deposition system are described.

  17. The Influence of nonuniform activity distribution on cellular dosimetry

    International Nuclear Information System (INIS)

    Naling, Song; Yuan, Tian; Liangan, Zhang; Guangfu, Dai

    2008-01-01

    S value is an important parameter in determination of absorbed dose in nuclear medicine and radiobiology. The distribution of radioactivity shows significant influence on the S value especially in microdosimetry. In present work, a semi Monte Carlo Model is developed to calculate the microdosimetric cellular S value for different micro-distributions of radioactivity, i.e. uniform, linear increase, linear decrease, exponential increase, exponential decrease and centroid distribution. Emission of alpha particles is simulated by Monte Carlo model and the energy imparted to the target volume is calculated by the analytical Continuous Slowing Down Approximation (CSDA) model and the spline interpolation of range-energy relationship. We calculate tables of S values for 213 Po and 210 Po with various dimensions and most important with various possible micro-distributions of radioactivity, such as linear increase, linear decrease, exponential increase and exponential decrease. Then we compare the S values from cell to cell of uniform distribution with the Hamacher's results to test the feasibility of our model. S values of some nonuniform micro-distributions are compared to the corresponding data of the uniform distribution. The possible sources of these differences are theoretical analyzed. (author)

  18. Liquid-metal flow in a rectangular duct with a non-uniform magnetic field

    International Nuclear Information System (INIS)

    Walker, J.S.

    1986-04-01

    This paper treats liquid-metal flow in rectangular ducts with thin conducting walls. A transverse magnetic field changes from a uniform strength upstream to a weaker uniform strength downstream. The Hartmann number and the interaction parameter are assumed to be large, while the magnetic Reynolds number is assumed to be small. If the magnetic field changes gradually over a long duct length, the velocity and pressure are nearly uniform in each cross section and the flow differs slightly from locally fully developed flow. If the magnetic field changes more abruptly over a shorter duct length, the velocity and pressure are much larger near the walls parallel to the magnetic field than in the central part of duct. Solutions for the pressure drops due to the magnetic field change are presented

  19. Biases in the OSSOS Detection of Large Semimajor Axis Trans-Neptunian Objects

    Science.gov (United States)

    Gladman, Brett; Shankman, Cory; OSSOS Collaboration

    2017-10-01

    The accumulating but small set of large semimajor axis trans-Neptunian objects (TNOs) shows an apparent clustering in the orientations of their orbits. This clustering must either be representative of the intrinsic distribution of these TNOs, or else have arisen as a result of observation biases and/or statistically expected variations for such a small set of detected objects. The clustered TNOs were detected across different and independent surveys, which has led to claims that the detections are therefore free of observational bias. This apparent clustering has led to the so-called “Planet 9” hypothesis that a super-Earth currently resides in the distant solar system and causes this clustering. The Outer Solar System Origins Survey (OSSOS) is a large program that ran on the Canada-France-Hawaii Telescope from 2013 to 2017, discovering more than 800 new TNOs. One of the primary design goals of OSSOS was the careful determination of observational biases that would manifest within the detected sample. We demonstrate the striking and non-intuitive biases that exist for the detection of TNOs with large semimajor axes. The eight large semimajor axis OSSOS detections are an independent data set, of comparable size to the conglomerate samples used in previous studies. We conclude that the orbital distribution of the OSSOS sample is consistent with being detected from a uniform underlying angular distribution.

  20. Optimal sensor placement for leakage detection and isolation in water distribution networks

    OpenAIRE

    Rosich Oliva, Albert; Sarrate Estruch, Ramon; Nejjari Akhi-Elarab, Fatiha

    2012-01-01

    In this paper, the problem of leakage detection and isolation in water distribution networks is addressed applying an optimal sensor placement methodology. The chosen technique is based on structural models and thus it is suitable to handle non-linear and large scale systems. A drawback of this technique arises when costs are assigned uniformly. A main contribution of this paper is the proposal of an iterative methodology that focuses on identifying essential sensors which ultimately leads to...

  1. Periodic and uniform nanogratings formed on cemented carbide by femtosecond laser scanning

    International Nuclear Information System (INIS)

    Lian, Yunsong; Deng, Jianxin; Xing, Youqiang; Lei, Shuting; Yu, Xiaoming

    2013-01-01

    Periodic and uniform nanogratings are fabricated by femtosecond laser scanning on cemented carbide. Specifically, three experiments are designed to study the influence of single pulse energy, scanning speed, and scanning spacing on the period and the uniformity of the formed nanogratings. The results show that the sample with single pulse energy of 2 μJ, scanning speed of 1000 μm/s, and scanning spacing of 5 μm shows the best quality of nanogratings among all the tested samples at different processing parameters. The uniformity of the nanogratings is largely determined by single pulse energy, scanning speed, and scanning spacing. Single pulse energy and scanning speed significantly affect the period of the nanogratings, whereas the period of the nanogratings maintains a fixed value under different scanning spacings. The period of the nanogratings increases gradually with the decrease of the single pulse energy and the increase of the scanning speed, respectively.

  2. Highly uniform residual layers for arrays of 3D nanoimprinted cavities in Fabry-Pérot-filter-array-based nanospectrometers

    Science.gov (United States)

    Memon, Imran; Shen, Yannan; Khan, Abdullah; Woidt, Carsten; Hillmer, Hartmut

    2016-04-01

    Miniaturized optical spectrometers can be implemented by an array of Fabry-Pérot (FP) filters. FP filters are composed of two highly reflecting parallel mirrors and a resonance cavity. Each filter transmits a small spectral band (filter line) depending on its individual cavity height. The optical nanospectrometer, a miniaturized FP-based spectrometer, implements 3D NanoImprint technology for the fabrication of multiple FP filter cavities in a single process step. However, it is challenging to avoid the dependency of residual layer (RL) thickness on the shape of the printed patterns in NanoImprint. Since in a nanospectrometer the filter cavities vary in height between neighboring FP filters and, thus, the volume of each cavity varies causing that the RL varies slightly or noticeably between different filters. This is one of the few disadvantages of NanoImprint using soft templates such as substrate conformal imprint lithography which is used in this paper. The advantages of large area soft templates can be revealed substantially if the problem of laterally inhomogeneous RLs can be avoided or reduced considerably. In the case of the nanospectrometer, non-uniform RLs lead to random variations in the designed cavity heights resulting in the shift of desired filter lines. To achieve highly uniform RLs, we report a volume-equalized template design with the lateral distribution of 64 different cavity heights into several units with each unit comprising four cavity heights. The average volume of each unit is kept constant to obtain uniform filling of imprint material per unit area. The imprint results, based on the volume-equalized template, demonstrate highly uniform RLs of 110 nm thickness.

  3. Implementing Assessment Engineering in the Uniform Certified Public Accountant (CPA) Examination

    Science.gov (United States)

    Burke, Matthew; Devore, Richard; Stopek, Josh

    2013-01-01

    This paper describes efforts to bring principled assessment design to a large-scale, high-stakes licensure examination by employing the frameworks of Assessment Engineering (AE), the Revised Bloom's Taxonomy (RBT), and Cognitive Task Analysis (CTA). The Uniform CPA Examination is practice-oriented and focuses on the skills of accounting. In…

  4. Higher albedos and size distribution of large transneptunian objects

    Science.gov (United States)

    Lykawka, Patryk Sofia; Mukai, Tadashi

    2005-11-01

    Transneptunian objects (TNOs) orbit beyond Neptune and do offer important clues about the formation of our solar system. Although observations have been increasing the number of discovered TNOs and improving their orbital elements, very little is known about elementary physical properties such as sizes, albedos and compositions. Due to TNOs large distances (>40 AU) and observational limitations, reliable physical information can be obtained only from brighter objects (supposedly larger bodies). According to size and albedo measurements available, it is evident the traditionally assumed albedo p=0.04 cannot hold for all TNOs, especially those with approximately absolute magnitudes H⩽5.5. That is, the largest TNOs possess higher albedos (generally >0.04) that strongly appear to increase as a function of size. Using a compilation of published data, we derived empirical relations which can provide estimations of diameters and albedos as a function of absolute magnitude. Calculations result in more accurate size/albedo estimations for TNOs with H⩽5.5 than just assuming p=0.04. Nevertheless, considering low statistics, the value p=0.04 sounds still convenient for H>5.5 non-binary TNOs as a group. We also discuss about physical processes (e.g., collisions, intrinsic activity and the presence of tenuous atmospheres) responsible for the increase of albedo among large bodies. Currently, all big TNOs (>700 km) would be capable to sustain thin atmospheres or icy frosts composed of CH 4, CO or N 2 even for body bulk densities as low as 0.5 g cm -3. A size-dependent albedo has important consequences for the TNOs size distribution, cumulative luminosity function and total mass estimations. According to our analysis, the latter can be reduced up to 50% if higher albedos are common among large bodies. Lastly, by analyzing orbital properties of classical TNOs ( 42AUbodies. For both populations, distinct absolute magnitude distributions are maximized for an inclination threshold

  5. 7 CFR 1006.61 - Computation of uniform prices.

    Science.gov (United States)

    2010-01-01

    ..., the market administrator shall compute a uniform butterfat price, a uniform skim milk price, and a... section. (b) Uniform skim milk price. The uniform skim milk price per hundredweight, rounded to the... paragraph (a) of this section times 3.5 pounds of butterfat; and (2) Multiply the uniform skim milk price...

  6. 7 CFR 1131.61 - Computation of uniform prices.

    Science.gov (United States)

    2010-01-01

    ..., the market administrator shall compute a uniform butterfat price, a uniform skim milk price, and a... section. (b) Uniform skim milk price. The uniform skim milk price per hundredweight, rounded to the... paragraph (a) of this section times 3.5 pounds of butterfat; and (2) Multiply the uniform skim milk price...

  7. 7 CFR 1007.61 - Computation of uniform prices.

    Science.gov (United States)

    2010-01-01

    ..., the market administrator shall compute a uniform butterfat price, a uniform skim milk price, and a... section. (b) Uniform skim milk price. The uniform skim milk price per hundredweight, rounded to the... paragraph (a) of this section times 3.5 pounds of butterfat; and (2) Multiply the uniform skim milk price...

  8. The impact of non-uniform channel layer growth on device characteristics in state of the Art Si/SiGe/Si p-metal oxide semiconductor field effect transistors

    International Nuclear Information System (INIS)

    Chang, A.C.K.; Ross, I.M.; Norris, D.J.; Cullis, A.G.; Tang, Y.T.; Cerrina, C.; Evans, A.G.R.

    2006-01-01

    In this study we have highlighted the effect of non-uniform channel layer growth by the direct correlation of the microstructure and electrical characteristics in state-of-the-art pseudomorphic Si/SiGe p-channel metal oxide semiconductor field effect transistor devices fabricated on Si. Two nominally identical sets of devices from adjacent locations of the same wafer were found to have radically different distributions in gate threshold voltages. Due to the close proximity and narrow gate length of the devices, focused ion beam milling was used to prepare a number of thin cross-sections from each of the two regions for subsequent analysis using transmission electron microscopy. It was found that devices from the region giving a very narrow range of gate threshold voltages exhibited a uniform microstructure in general agreement with the intended growth parameters. However, in the second region, which showed a large spread in the gate threshold voltages, profound anomalies in the microstructure were observed. These anomalies consisted of fluctuations in the quality and thickness of the SiGe strained layers. The non-uniform growth of the strained SiGe layer clearly accounted for the poorly controlled threshold voltages of these devices. The results emphasize the importance of good layer growth uniformity to ensure optimum device yield

  9. 7 CFR 1005.61 - Computation of uniform prices.

    Science.gov (United States)

    2010-01-01

    ... month, the market administrator shall compute a uniform butterfat price, a uniform skim milk price, and...) and (a)(2) of this section. (b) Uniform skim milk price. The uniform skim milk price per hundredweight... paragraph (a) of this section times 3.5 pounds of butterfat; and (2) Multiply the uniform skim milk price...

  10. Analysis of large urban fires

    International Nuclear Information System (INIS)

    Kang, S.W.; Reitter, T.A.; Takata, A.N.

    1984-11-01

    Fires in urban areas caused by a nuclear burst are analyzed as a first step towards determining their smoke-generation chacteristics, which may have grave implications for global-scale climatic consequences. A chain of events and their component processes which would follow a nuclear attack are described. A numerical code is currently being developed to calculate ultimately the smoke production rate for a given attack scenario. Available models for most of the processes are incorporated into the code. Sample calculations of urban fire-development history performed in the code for an idealized uniform city are presented. Preliminary results indicate the importance of the wind, thermal radiation transmission, fuel distributions, and ignition thresholds on the urban fire spread characteristics. Future plans are to improve the existing models and develop new ones to characterize smoke production from large urban fires. 21 references, 18 figures

  11. HAlign-II: efficient ultra-large multiple sequence alignment and phylogenetic tree reconstruction with distributed and parallel computing.

    Science.gov (United States)

    Wan, Shixiang; Zou, Quan

    2017-01-01

    Multiple sequence alignment (MSA) plays a key role in biological sequence analyses, especially in phylogenetic tree construction. Extreme increase in next-generation sequencing results in shortage of efficient ultra-large biological sequence alignment approaches for coping with different sequence types. Distributed and parallel computing represents a crucial technique for accelerating ultra-large (e.g. files more than 1 GB) sequence analyses. Based on HAlign and Spark distributed computing system, we implement a highly cost-efficient and time-efficient HAlign-II tool to address ultra-large multiple biological sequence alignment and phylogenetic tree construction. The experiments in the DNA and protein large scale data sets, which are more than 1GB files, showed that HAlign II could save time and space. It outperformed the current software tools. HAlign-II can efficiently carry out MSA and construct phylogenetic trees with ultra-large numbers of biological sequences. HAlign-II shows extremely high memory efficiency and scales well with increases in computing resource. THAlign-II provides a user-friendly web server based on our distributed computing infrastructure. HAlign-II with open-source codes and datasets was established at http://lab.malab.cn/soft/halign.

  12. Dressed for Success? The Effect of School Uniforms on Student Achievement and Behavior. NBER Working Paper No. 17337

    Science.gov (United States)

    Gentile, Elisabetta; Imberman, Scott A.

    2011-01-01

    Uniform use in public schools is rising, but we know little about how they affect students. Using a unique dataset from a large urban school district in the southwest United States, we assess how uniforms affect behavior, achievement and other outcomes. Each school in the district determines adoption independently, providing variation over schools…

  13. Measurement of reactivity effect caused by nonuniform fuel distribution

    International Nuclear Information System (INIS)

    Yamane, Yoshihiro; Hirano, Yasushi; Yasui, Hazime; Nishina, Kojiro; Shiroya, Seiji

    1991-01-01

    A reactivity effect due to a spatial variation of nuclear fuel concentration is an important problem in a reprocessing plant. To estimate this reactivity effect theoretically, the ''Goertzel's necessary condition, and th Fuel Importance'' theory have been proposed. In order to verify these theories, we have performed systematic measurements of reactivity effect due to the nonuniformity in the fuel distribution within the Kyoto University Critical Assembly. Neutron flux distribution and Fuel Importance distribution were also determined. A nonuniform assembly whose fuel concentration in the center region was 40% higher than the uniform one was found to have an excess reactivity of 0.3%Δk/k, with the same total uranium mass for which the uniform assembly was just critical. Moreover, its spatial distribution of thermal neutron flux and of Fuel Importance were more flat than those of the uniform assembly, as expected by the Goertzel's condition and the Fuel Importance theory. (Author)

  14. Large-scale synthesis of reduced graphene oxides with uniformly coated polyaniline for supercapacitor applications.

    Science.gov (United States)

    Salunkhe, Rahul R; Hsu, Shao-Hui; Wu, Kevin C W; Yamauchi, Yusuke

    2014-06-01

    We report an effective route for the preparation of layered reduced graphene oxide (rGO) with uniformly coated polyaniline (PANI) layers. These nanocomposites are synthesized by chemical oxidative polymerization of aniline monomer in the presence of layered rGO. SEM, TEM, X-ray photoelectron spectroscopy (XPS), FTIR, and Raman spectroscopy analysis results demonstrated that reduced graphene oxide-polyaniline (rGO-PANI) nanocomposites are successfully synthesized. Because of synergistic effects, rGO-PANI nanocomposites prepared by this approach exhibit excellent capacitive performance with a high specific capacitance of 286 F g(-1) and high cycle reversibility of 94 % after 2000 cycles. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. A uniform laminar air plasma plume with large volume excited by an alternating current voltage

    Science.gov (United States)

    Li, Xuechen; Bao, Wenting; Chu, Jingdi; Zhang, Panpan; Jia, Pengying

    2015-12-01

    Using a plasma jet composed of two needle electrodes, a laminar plasma plume with large volume is generated in air through an alternating current voltage excitation. Based on high-speed photography, a train of filaments is observed to propagate periodically away from their birth place along the gas flow. The laminar plume is in fact a temporal superposition of the arched filament train. The filament consists of a negative glow near the real time cathode, a positive column near the real time anode, and a Faraday dark space between them. It has been found that the propagation velocity of the filament increases with increasing the gas flow rate. Furthermore, the filament lifetime tends to follow a normal distribution (Gaussian distribution). The most probable lifetime decreases with increasing the gas flow rate or decreasing the averaged peak voltage. Results also indicate that the real time peak current decreases and the real time peak voltage increases with the propagation of the filament along the gas flow. The voltage-current curve indicates that, in every discharge cycle, the filament evolves from a Townsend discharge to a glow one and then the discharge quenches. Characteristic regions including a negative glow, a Faraday dark space, and a positive column can be discerned from the discharge filament. Furthermore, the plasma parameters such as the electron density, the vibrational temperature and the gas temperature are investigated based on the optical spectrum emitted from the laminar plume.

  16. Spacetime transformations from a uniformly accelerated frame

    International Nuclear Information System (INIS)

    Friedman, Yaakov; Scarr, Tzvi

    2013-01-01

    We use the generalized Fermi–Walker transport to construct a one-parameter family of inertial frames which are instantaneously comoving to a uniformly accelerated observer. We explain the connection between our approach and that of Mashhoon. We show that our solutions of uniformly accelerated motion have constant acceleration in the comoving frame. Assuming the weak hypothesis of locality, we obtain local spacetime transformations from a uniformly accelerated frame K′ to an inertial frame K. The spacetime transformations between two uniformly accelerated frames with the same acceleration are Lorentz. We compute the metric at an arbitrary point of a uniformly accelerated frame. (paper)

  17. A Unified Network Security Architecture for Large, Distributed Networks, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In typical, multi-organizational networking environments, it is difficult to define and maintain a uniform authentication scheme that provides users with easy access...

  18. The effect of increased irradiation uniformity on imprinting by 351-nm laser light

    International Nuclear Information System (INIS)

    Boehly, T.R.; Smalyuk, V.A.; Meyerhofer, D.D.; Knauer, J.P.; Bradley, D.K.; Verdon, C.P.; Kalantar, D.

    1997-01-01

    The acceleration-driven growth of perturbations initially seeded (or imprinted) by irradiation nonuniformities is a major concern for direct-drive ICF. We report on experiments where unperturbed, CH 2 targets were irradiated with 3-ns square pulses at 2x10 14 W/cm 2 using five overlapped UV beams. The uniformity of these beams was varied and subsequent unstable growth of irradiation imprinting was observed using time-gated x-radiography. We demonstrate that increased irradiation uniformity reduces imprinting, and we show the beneficial effects of distributed polarization rotators a new beam-smoothing device. In addition, we discuss experiments using a ' perturbing beam' to study the time dependence of imprinting. copyright 1997 American Institute of Physics

  19. Cellular- and micro-dosimetry of heterogeneously distributed tritium.

    Science.gov (United States)

    Chao, Tsi-Chian; Wang, Chun-Ching; Li, Junli; Li, Chunyan; Tung, Chuan-Jong

    2012-01-01

    The assessment of radiotoxicity for heterogeneously distributed tritium should be based on the subcellular dose and relative biological effectiveness (RBE) for cell nucleus. In the present work, geometry-dependent absorbed dose and RBE were calculated using Monte Carlo codes for tritium in the cell, cell surface, cytoplasm, or cell nucleus. Penelope (PENetration and Energy LOss of Positrins and Electrons) code was used to calculate the geometry-dependent absorbed dose, lineal energy, and electron fluence spectrum. RBE for the intestinal crypt regeneration was calculated using a lineal energy-dependent biological weighting function. RBE for the induction of DNA double strand breaks was estimated using a nucleotide-level map for clustered DNA lesions of the Monte Carlo damage simulation (MCDS) code. For a typical cell of 10 μm radius and 5 μm nuclear radius, tritium in the cell nucleus resulted in much higher RBE-weighted absorbed dose than tritium distributed uniformly. Conversely, tritium distributed on the cell surface led to trivial RBE-weighted absorbed dose due to irradiation geometry and great attenuation of beta particles in the cytoplasm. For tritium uniformly distributed in the cell, the RBE-weighted absorbed dose was larger compared to tritium uniformly distributed in the tissue. Cellular- and micro-dosimetry models were developed for the assessment of heterogeneously distributed tritium.

  20. Precipitation patterns control the distribution and export of large wood at the catchment scale

    OpenAIRE

    Il Seo, Jung; Nakamura, Futoshi; Chun, Kun Woo; Kim, Suk Woo; Grant, Gordon E.

    2015-01-01

    Large wood (LW) plays an important role in river ecosystems, but LW-laden floods may cause serious damage to human lives and property. The relationship between precipitation patterns and variations in LW distribution and export at the watershed scale is poorly understood. To explore these linkages, we examined differences in LW distribution as a function of channel morphologies in six watersheds located in southern and northern Japan and analysed the impacts of different precipitation pattern...

  1. Rivulet flow round a horizontal cylinder subject to a uniform surface shear stress

    KAUST Repository

    Paterson, C.; Wilson, S. K.; Duffy, B. R.

    2014-01-01

    large stationary horizontal cylinder subject to a prescribed uniform azimuthal surface shear stress is investigated. In particular, we focus on the case where the volume flux is downwards but the shear stress is upwards, for which there is always a

  2. Classical understanding of electron vortex beams in a uniform magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yeong Deok [Department of Computer Science and Engineering, Woosuk University, Wanju, Cheonbuk, 565-701 (Korea, Republic of); Choi, Taeseung, E-mail: tschoi@swu.ac.kr [Division of Applied Food System, College of Natural Science, Seoul Women' s University, Seoul 139-774 (Korea, Republic of); School of Computational Sciences, Korea Institute for Advanced Study, Seoul 130-012 (Korea, Republic of)

    2017-04-25

    Recently, interesting observations on electron vortex beams have been made. We propose a classical model that shows vortex-like motion due to suitably-synchronized motion of each electron's cyclotron motion in a uniform magnetic field. It is shown that some basic features of electron vortex beams in a uniform magnetic field, such as azimuthal currents, the relation between energy and kinetic angular momentum, and the parallel-axis theorem are understandable by using this classical model. We also show that the time-dependence of kinetic angular momentum of electron vortex beams could be understood as an effect of a specific nonuniform distribution of classical electrons. - Highlights: • A classical model for electron vortex beams is proposed. • The basic features of azimuthal currents could be understood by using this model. • The kinetic angular momentum of electron vortex beams is intuitively understandable.

  3. Monofractal or multifractal: a case study of spatial distribution of mining-induced seismic activity

    Directory of Open Access Journals (Sweden)

    M. Eneva

    1994-01-01

    Full Text Available Using finite data sets and limited size of study volumes may result in significant spurious effects when estimating the scaling properties of various physical processes. These effects are examined with an example featuring the spatial distribution of induced seismic activity in Creighton Mine (northern Ontario, Canada. The events studied in the present work occurred during a three-month period, March-May 1992, within a volume of approximate size 400 x 400 x 180 m3. Two sets of microearthquake locations are studied: Data Set 1 (14,338 events and Data Set 2 (1654 events. Data Set 1 includes the more accurately located events and amounts to about 30 per cent of all recorded data. Data Set 2 represents a portion of the first data set that is formed by the most accurately located and the strongest microearthquakes. The spatial distribution of events in the two data sets is examined for scaling behaviour using the method of generalized correlation integrals featuring various moments q. From these, generalized correlation dimensions are estimated using the slope method. Similar estimates are made for randomly generated point sets using the same numbers of events and the same study volumes as for the real data. Uniform and monofractal random distributions are used for these simulations. In addition, samples from the real data are randomly extracted and the dimension spectra for these are examined as well. The spectra for the uniform and monofractal random generations show spurious multifractality due only to the use of finite numbers of data points and limited size of study volume. Comparing these with the spectra of dimensions for Data Set 1 and Data Set 2 allows us to estimate the bias likely to be present in the estimates for the real data. The strong multifractality suggested by the spectrum for Data Set 2 appears to be largely spurious; the spatial distribution, while different from uniform, could originate from a monofractal process. The spatial

  4. Hybrid shared/distributed parallelism for 3D characteristics transport solvers

    International Nuclear Information System (INIS)

    Dahmani, M.; Roy, R.

    2005-01-01

    In this paper, we will present a new hybrid parallel model for solving large-scale 3-dimensional neutron transport problems used in nuclear reactor simulations. Large heterogeneous reactor problems, like the ones that occurs when simulating Candu cores, have remained computationally intensive and impractical for routine applications on single-node or even vector computers. Based on the characteristics method, this new model is designed to solve the transport equation after distributing the calculation load on a network of shared memory multi-processors. The tracks are either generated on the fly at each characteristics sweep or stored in sequential files. The load balancing is taken into account by estimating the calculation load of tracks and by distributing batches of uniform load on each node of the network. Moreover, the communication overhead can be predicted after benchmarking the latency and bandwidth using appropriate network test suite. These models are useful for predicting the performance of the parallel applications and to analyze the scalability of the parallel systems. (authors)

  5. Large-time behavior of solutions to a reaction-diffusion system with distributed microstructure

    NARCIS (Netherlands)

    Muntean, A.

    2009-01-01

    Abstract We study the large-time behavior of a class of reaction-diffusion systems with constant distributed microstructure arising when modeling diffusion and reaction in structured porous media. The main result of this Note is the following: As t ¿ 8 the macroscopic concentration vanishes, while

  6. Pinning down the large-x gluon with NNLO top-quark pair differential distributions

    NARCIS (Netherlands)

    Czakon, Michał; Hartland, Nathan P.; Mitov, Alexander; Nocera, Emanuele R.; Rojo, Juan

    2016-01-01

    Top-quark pair production at the LHC is directly sensitive to the gluon PDF at large x. While total cross-section data is already included in several PDF determinations, differential distributions are not, because the corresponding NNLO calculations have become available only recently. In this work

  7. Uniformly sized gold nanoparticles derived from PS-b-P2VP block copolymer templates for the controllable synthesis of Si nanowires.

    Science.gov (United States)

    Lu, Jennifer Q; Yi, Sung Soo

    2006-04-25

    A monolayer of gold-containing surface micelles has been produced by spin-coating solution micelles formed by the self-assembly of the gold-modified polystyrene-b-poly(2-vinylpyridine) block copolymer in toluene. After oxygen plasma removed the block copolymer template, highly ordered and uniformly sized nanoparticles have been generated. Unlike other published methods that require reduction treatments to form gold nanoparticles in the zero-valent state, these as-synthesized nanoparticles are in form of metallic gold. These gold nanoparticles have been demonstrated to be an excellent catalyst system for growing small-diameter silicon nanowires. The uniformly sized gold nanoparticles have promoted the controllable synthesis of silicon nanowires with a narrow diameter distribution. Because of the ability to form a monolayer of surface micelles with a high degree of order, evenly distributed gold nanoparticles have been produced on a surface. As a result, uniformly distributed, high-density silicon nanowires have been generated. The process described herein is fully compatible with existing semiconductor processing techniques and can be readily integrated into device fabrication.

  8. Uniform elemental analysis of materials by sputtering and photoionization mass spectrometry

    International Nuclear Information System (INIS)

    Chun, He; Basler, J.N.; Becker, C.H.

    1997-01-01

    Analysis of the elemental composition of surfaces commonly involves techniques in which atoms or ions are ablated from the material's surface and detected by mass spectrometry. Secondary-ion mass spectrometry is widely used for detection with high sensitivity (down to a few parts per billion) but technical problems prevent it from being truly quantitative. Some of these problems are circumvented by nonresonant laser post-ionization of sputtered atoms followed by time-of-flight mass spectrometry (surface analysis by laser ionization: SALI). But when there are large differences in ionization probabilities amongst different elements in the material, the detection sensitivity can be non-uniform and accurate quantification remains out of reach. Here we report that highly uniform, quantitative and sensitive analysis of materials can be achieved using a high-energy (5-keV) ion beam for sputtering coupled with a very-high-intensity laser to induce multiphoton ionization of the sputtered atoms. We show uniform elemental sensitivity for several samples containing elements with very different ionization potentials, suggesting that this approach can now be regarded as quantitative for essentially any material. (author)

  9. How uniform incentives can provide a negative motivation: an application to early school leaving in two large cities

    NARCIS (Netherlands)

    de Witte, K.; van Klaveren, C.

    2010-01-01

    In case of regional discretionary on the implementation of policy measures, central govern­ments may consider the differences in outcomes as an indication on the effectiveness of policy. In turn, to motivate regional policy makers uniform incentives might be developed. However, if the underlying

  10. Long GRBs sources population non-uniformity

    Science.gov (United States)

    Arkhangelskaja, Irene

    Long GRBs observed in the very wide energy band. It is possible to separate two subsets of GRBs with high energy component (E > 500 MeV) presence. First type events energy spectra in low and high energy intervals are similar (as for GRB 021008) and described by Band, power law or broken power law models look like to usual bursts without emission in tens MeV region. For example, Band spectrum of GRB080916C covering 6 orders of magnitude. Second ones contain new additional high energy spectral component (for example, GRB 050525B and GRB 090902B). Both types of GRBs observed since CGRO mission beginning. The low energy precursors existence are typical for all types bursts. Both types of bursts temporal profiles can be similar in the various energy regions during some events or different in other cases. The absence of hard to soft evolution in low energy band and (or) presence of high energy precursors for some events are the special features of second class of GRBs by the results of preliminary data analysis and this facts gives opportunities to suppose differences between these two GRBs subsets sources. Also the results of long GRB redshifts distribution analysis have shown its shape contradiction to uniform population objects one for our Metagalaxy to both total and various redshifts definition methods GRBs sources samples. These evidences allow making preliminary conclusion about non-uniformity of long GRBs sources population.

  11. Nanosecond laser texturing of uniformly and non-uniformly wettable micro structured metal surfaces for enhanced boiling heat transfer

    Energy Technology Data Exchange (ETDEWEB)

    Zupančič, Matevž, E-mail: matevz.zupancic@fs.uni-lj.si; Može, Matic; Gregorčič, Peter; Golobič, Iztok

    2017-03-31

    Highlights: • Surfaces with periodically changed wettability were produced by a ns marking laser. • Heat transfer was investigated on uniformly and non-uniformly wettable surfaces. • Microporous surfaces with non-uniform wettability enhance boiling heat transfer. • The most bubble nucleations were observed in the vicinity of the microcavities. • Results agree with the predictions of the nucleation criteria. - Abstract: Microstructured uniformly and non-uniformly wettable surfaces were created on 25-μm-thin stainless steel foils by laser texturing using a marking nanosecond Nd:YAG laser (λ = 1064 nm) and utilizing various laser fluences and scan line separations. High-speed photography and high-speed IR thermography were used to investigate nucleate boiling heat transfer on the microstructured surfaces. The most pronounced results were obtained on a surface with non-uniform microstructure and non-uniform wettability. The obtained results show up to a 110% higher heat transfer coefficients and 20–40 times higher nucleation site densities compared to the untextured surface. We show that the number of active nucleation sites is significantly increased in the vicinity of microcavities that appeared in areas with the smallest (10 μm) scan line separation. Furthermore, this confirms the predictions of nucleation criteria and proves that straightforward, cost-effective nanosecond laser texturing allows the production of cavities with diameters of up to a few micrometers and surfaces with non-uniform wettability. Additionally, this opens up important possibilities for a more deterministic control over the complex boiling process.

  12. Distributed Large Data-Object Environments: End-to-End Performance Analysis of High Speed Distributed Storage Systems in Wide Area ATM Networks

    Science.gov (United States)

    Johnston, William; Tierney, Brian; Lee, Jason; Hoo, Gary; Thompson, Mary

    1996-01-01

    We have developed and deployed a distributed-parallel storage system (DPSS) in several high speed asynchronous transfer mode (ATM) wide area networks (WAN) testbeds to support several different types of data-intensive applications. Architecturally, the DPSS is a network striped disk array, but is fairly unique in that its implementation allows applications complete freedom to determine optimal data layout, replication and/or coding redundancy strategy, security policy, and dynamic reconfiguration. In conjunction with the DPSS, we have developed a 'top-to-bottom, end-to-end' performance monitoring and analysis methodology that has allowed us to characterize all aspects of the DPSS operating in high speed ATM networks. In particular, we have run a variety of performance monitoring experiments involving the DPSS in the MAGIC testbed, which is a large scale, high speed, ATM network and we describe our experience using the monitoring methodology to identify and correct problems that limit the performance of high speed distributed applications. Finally, the DPSS is part of an overall architecture for using high speed, WAN's for enabling the routine, location independent use of large data-objects. Since this is part of the motivation for a distributed storage system, we describe this architecture.

  13. Helium ion distributions in a 4 kJ plasma focus device by 1 mm-thick large-size polycarbonate detectors

    Energy Technology Data Exchange (ETDEWEB)

    Sohrabi, M., E-mail: dr_msohrabi@yahoo.com; Habibi, M.; Ramezani, V.

    2014-11-14

    Helium ion beam profile, angular and iso-ion beam distributions in 4 kJ Amirkabir plasma focus (APF) device were effectively observed by the unaided eyes and studied in single 1 mm-thick large-diameter (20 cm) polycarbonate track detectors (PCTD). The PCTDs were processed by 50 Hz–HV electrochemical etching using a large-size ECE chamber. The results show that helium ions produced in the APF device have a ring-shaped angular distribution peaked at an angle of ∼±60° with respect to the top of the anode. Some information on the helium ion energy and distributions is also provided. The method is highly effective for ion beam studies. - Highlights: • Helium iso-ion beam profile and angular distributions were studied in the 4 kJ APF device. • Large-area 1 mm-thick polycarbonate detectors were processed by 50 Hz-HV ECE. • Helium ion beam profile and distributions were observed by unaided eyes in a single detector. • Helium ion profile has ring-shaped distributions with energies lower at the ring location. • Helium iso-ion track density, diameter and energy distributions are estimated.

  14. 24 CFR 5.801 - Uniform financial reporting standards.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Uniform financial reporting... and Urban Development GENERAL HUD PROGRAM REQUIREMENTS; WAIVERS Uniform Financial Reporting Standards § 5.801 Uniform financial reporting standards. (a) Applicability. This subpart H implements uniform...

  15. Decidability of uniform recurrence of morphic sequences

    OpenAIRE

    Durand , Fabien

    2012-01-01

    We prove that the uniform recurrence of morphic sequences is decidable. For this we show that the number of derived sequences of uniformly recurrent morphic sequences is bounded. As a corollary we obtain that uniformly recurrent morphic sequences are primitive substitutive sequences.

  16. Projection-based Bayesian recursive estimation of ARX model with uniform innovations

    Czech Academy of Sciences Publication Activity Database

    Kárný, Miroslav; Pavelková, Lenka

    2007-01-01

    Roč. 56, 9/10 (2007), s. 646-655 ISSN 0167-6911 R&D Projects: GA AV ČR 1ET100750401; GA MŠk 2C06001; GA MDS 1F43A/003/120 Institutional research plan: CEZ:AV0Z10750506 Keywords : ARX model * Bayesian recursive estimation * Uniform distribution Subject RIV: BC - Control Systems Theory Impact factor: 1.634, year: 2007 http://dx.doi.org/10.1016/j.sysconle.2007.03.005

  17. School uniforms: tradition, benefit or predicament?

    OpenAIRE

    Van Aardt, Annette Marie; Wilken, Ilani

    2012-01-01

    This article focuses on the controversies surrounding school uniforms. Roleplayers in this debate in South Africa are parents, learners and educators, and arguments centre on aspects such as identity, economy and the equalising effect of school uniforms, which are considered in the literature to be benefits. Opposing viewpoints highlight the fact that compulsory uniforms infringe on learners’ constitutional rights to self-expression. The aim of this research was to determine the perspectives ...

  18. Longitudinal distribution and parameters of large wood in a Mediterranean ephemeral stream

    Science.gov (United States)

    Galia, T.; Škarpich, V.; Tichavský, R.; Vardakas, L.; Šilhán, K.

    2018-06-01

    Although large wood (LW) has been intensively studied in forested basins of humid temperate climates, data on LW patterns in different fluvial environments are rather scarce. Therefore, we investigated the dimensions, characteristics, longitudinal distribution, and dynamics of LW along a 4.05-km-long reach of an ephemeral channel typical of European Mediterranean mountainous landscape (Sfakiano Gorge, Crete, Greece). We analysed a total of 795 LW pieces, and the mean observed abundance of LW was generally lower (14.3 m3/ha of active valley floor or 19.6 LW pieces/100 m of stream length) than is usually documented for more humid environments. The number of LW pieces was primarily controlled by trees growing on the valley floor. These living trees acted as important LW supply agents (by tree throws or the supply of individual branches with sufficient LW dimensions) and flow obstructions during large flood events, causing storage of transported LW pieces in jams. However, the downstream transport of LW is probably episodic, and large jams are likely formed only during major floods; after >15 years, we still observed significant imprints of the last major flood event on the present distribution of LW. The geomorphic function of LW in the studied stream can only be perceived to be a spatially limited stabilising element for sediments, which was documented by a few accumulations of coarse clastic material by LW steps and jams.

  19. Body fixed frame, rigid gauge rotations and large N random fields in QCD

    International Nuclear Information System (INIS)

    Levit, S.

    1995-01-01

    The ''body fixed frame'' with respect to local gauge transformations is introduced. Rigid gauge ''rotations'' in QCD and their Schroedinger equation are studied for static and dynamic quarks. Possible choices of the rigid gauge field configuration corresponding to a non-vanishing static colormagnetic field in the ''body fixed'' frame are discussed. A gauge invariant variational equation is derived in this frame. For large number N of colors the rigid gauge field configuration is regarded as random with maximally random probability distribution under constraints on macroscopic-like quantities. For the uniform magnetic field the joint probability distribution of the field components is determined by maximizing the appropriate entropy under the area law constraint for the Wilson loop. In the quark sector the gauge invariance requires the rigid gauge field configuration to appear not only as a background but also as inducing an instantaneous quark-quark interaction. Both are random in the large N limit. (orig.)

  20. Uniform and non-uniform inlet temperature of a vertical hot water jet injected into a rectangular tank

    KAUST Repository

    El-Amin, Mohamed; Sun, Shuyu

    2010-01-01

    In most of real-world applications, such as the case of heat stores, inlet is not kept at a constant temperature but it may vary with time during charging process. In this paper, a vertical water jet injected into a rectangular storage tank is measured experimentally and simulated numerically. Two cases of study are considered; one is a hot water jet with uniform inlet temperature (UIT) injected into a cold water tank, and the other is a cold water jet with non-uniform inlet temperature (NUIT) injected into a hot water tank. Three different temperature differences and three different flow rates are studied for the hot water jet with UIT which is injected into a cold water tank. Also, three different initial temperatures with constant flow rate as well as three different flow rates with constant initial temperature are considered for the cold jet with NUIT which is injected into a hot water tank. Turbulence intensity at the inlet as well as Reynolds number for the NUIT cases are therefore functions of inlet temperature and time. Both experimental measurements and numerical calculations are carried out for the same measured flow and thermal conditions. The realizable k-ε model is used for modeling the turbulent flow. Numerical solutions are obtained for unsteady flow while pressure, velocity, temperature and turbulence distributions inside the water tank are analyzed. The simulated results are compared to the measured results, and they show a good agreement at low temperatures. © 2010 IEEE.

  1. Uniform and non-uniform inlet temperature of a vertical hot water jet injected into a rectangular tank

    KAUST Repository

    El-Amin, Mohamed

    2010-12-01

    In most of real-world applications, such as the case of heat stores, inlet is not kept at a constant temperature but it may vary with time during charging process. In this paper, a vertical water jet injected into a rectangular storage tank is measured experimentally and simulated numerically. Two cases of study are considered; one is a hot water jet with uniform inlet temperature (UIT) injected into a cold water tank, and the other is a cold water jet with non-uniform inlet temperature (NUIT) injected into a hot water tank. Three different temperature differences and three different flow rates are studied for the hot water jet with UIT which is injected into a cold water tank. Also, three different initial temperatures with constant flow rate as well as three different flow rates with constant initial temperature are considered for the cold jet with NUIT which is injected into a hot water tank. Turbulence intensity at the inlet as well as Reynolds number for the NUIT cases are therefore functions of inlet temperature and time. Both experimental measurements and numerical calculations are carried out for the same measured flow and thermal conditions. The realizable k-ε model is used for modeling the turbulent flow. Numerical solutions are obtained for unsteady flow while pressure, velocity, temperature and turbulence distributions inside the water tank are analyzed. The simulated results are compared to the measured results, and they show a good agreement at low temperatures. © 2010 IEEE.

  2. Studying uniform thickness II: Transversely nonsimple iterated torus knots

    DEFF Research Database (Denmark)

    LaFountain, Douglas

    2011-01-01

    We prove that an iterated torus knot type in the standard contact 3-sphere fails the uniform thickness property (UTP) if and only if it is formed from repeated positive cablings, which is precisely when an iterated torus knot supports the standard contact structure. This is the first complete UTP...... classification for a large class of knots. We also show that all iterated torus knots that fail the UTP support cabling knot types that are transversely non-simple....

  3. Transition Experiments on Large Bluntness Cones with Distributed Roughness in Hypersonic Flight

    Science.gov (United States)

    Reda, Daniel. C.; Wilder, Michael C.; Prabhu, Dinesh K.

    2012-01-01

    Large bluntness cones with smooth nosetips and roughened frusta were flown in the NASA Ames hypersonic ballistic range at a Mach number of 10 through quiescent air environments. Global surface intensity (temperature) distributions were optically measured and analyzed to determine transition onset and progression over the roughened surface. Real-gas Navier-Stokes calculations of model flowfields, including laminar boundary layer development in these flowfields, were conducted to predict values of key dimensionless parameters used to correlate transition on such configurations in hypersonic flow. For these large bluntness cases, predicted axial distributions of the roughness Reynolds number showed (for each specified freestream pressure) that this parameter was a maximum at the physical beginning of the roughened zone and decreased with increasing run length along the roughened surface. Roughness-induced transition occurred downstream of this maximum roughness Reynolds number location, and progressed upstream towards the beginning of the roughened zone as freestream pressure was systematically increased. Roughness elements encountered at the upstream edge of the roughened frusta thus acted like a finite-extent trip array, consistent with published results concerning the tripping effectiveness of roughness bands placed on otherwise smooth surfaces.

  4. Achieving uniform efficient illumination with multiple asymmetric compound parabolic luminaires

    Science.gov (United States)

    Gordon, Jeffrey M.; Kashin, Peter

    1994-01-01

    Luminaire designs based on multiple asymmetric nonimaging compound parabolic reflectors are proposed for 2-D illumination applications that require highly uniform far-field illuminance, while ensuring maximal lighting efficiency and sharp angular cutoffs. The new designs derive from recent advances in nonimaging secondary concentrators for line-focus solar collectors. The light source is not treated as a single entity, but rather is divided into two or more separate adjoining sources. An asymmetric compound parabolic luminaire is then designed around each half-source. Attaining sharp cutoffs requires relatively large reflectors. However, severe truncation of the reflectors renders these devices as compact as many conventional luminaires, at the penalty of a small fraction of the radiation being emitted outside the nominal cutoff. The configurations that maximize the uniformity of far-field illuminance offer significant improvements in flux homogeneity relative to alternative designs to date.

  5. Distributed weighted least-squares estimation with fast convergence for large-scale systems☆

    Science.gov (United States)

    Marelli, Damián Edgardo; Fu, Minyue

    2015-01-01

    In this paper we study a distributed weighted least-squares estimation problem for a large-scale system consisting of a network of interconnected sub-systems. Each sub-system is concerned with a subset of the unknown parameters and has a measurement linear in the unknown parameters with additive noise. The distributed estimation task is for each sub-system to compute the globally optimal estimate of its own parameters using its own measurement and information shared with the network through neighborhood communication. We first provide a fully distributed iterative algorithm to asymptotically compute the global optimal estimate. The convergence rate of the algorithm will be maximized using a scaling parameter and a preconditioning method. This algorithm works for a general network. For a network without loops, we also provide a different iterative algorithm to compute the global optimal estimate which converges in a finite number of steps. We include numerical experiments to illustrate the performances of the proposed methods. PMID:25641976

  6. Distributed weighted least-squares estimation with fast convergence for large-scale systems.

    Science.gov (United States)

    Marelli, Damián Edgardo; Fu, Minyue

    2015-01-01

    In this paper we study a distributed weighted least-squares estimation problem for a large-scale system consisting of a network of interconnected sub-systems. Each sub-system is concerned with a subset of the unknown parameters and has a measurement linear in the unknown parameters with additive noise. The distributed estimation task is for each sub-system to compute the globally optimal estimate of its own parameters using its own measurement and information shared with the network through neighborhood communication. We first provide a fully distributed iterative algorithm to asymptotically compute the global optimal estimate. The convergence rate of the algorithm will be maximized using a scaling parameter and a preconditioning method. This algorithm works for a general network. For a network without loops, we also provide a different iterative algorithm to compute the global optimal estimate which converges in a finite number of steps. We include numerical experiments to illustrate the performances of the proposed methods.

  7. Visual properties and memorising scenes: Effects of image-space sparseness and uniformity.

    Science.gov (United States)

    Lukavský, Jiří; Děchtěrenko, Filip

    2017-10-01

    Previous studies have demonstrated that humans have a remarkable capacity to memorise a large number of scenes. The research on memorability has shown that memory performance can be predicted by the content of an image. We explored how remembering an image is affected by the image properties within the context of the reference set, including the extent to which it is different from its neighbours (image-space sparseness) and if it belongs to the same category as its neighbours (uniformity). We used a reference set of 2,048 scenes (64 categories), evaluated pairwise scene similarity using deep features from a pretrained convolutional neural network (CNN), and calculated the image-space sparseness and uniformity for each image. We ran three memory experiments, varying the memory workload with experiment length and colour/greyscale presentation. We measured the sensitivity and criterion value changes as a function of image-space sparseness and uniformity. Across all three experiments, we found separate effects of 1) sparseness on memory sensitivity, and 2) uniformity on the recognition criterion. People better remembered (and correctly rejected) images that were more separated from others. People tended to make more false alarms and fewer miss errors in images from categorically uniform portions of the image-space. We propose that both image-space properties affect human decisions when recognising images. Additionally, we found that colour presentation did not yield better memory performance over grayscale images.

  8. Desynchronization boost by non-uniform coordinated reset stimulation in ensembles of pulse-coupled neurons

    Science.gov (United States)

    Lücken, Leonhard; Yanchuk, Serhiy; Popovych, Oleksandr V.; Tass, Peter A.

    2013-01-01

    Several brain diseases are characterized by abnormal neuronal synchronization. Desynchronization of abnormal neural synchrony is theoretically compelling because of the complex dynamical mechanisms involved. We here present a novel type of coordinated reset (CR) stimulation. CR means to deliver phase resetting stimuli at different neuronal sub-populations sequentially, i.e., at times equidistantly distributed in a stimulation cycle. This uniform timing pattern seems to be intuitive and actually applies to the neural network models used for the study of CR so far. CR resets the population to an unstable cluster state from where it passes through a desynchronized transient, eventually resynchronizing if left unperturbed. In contrast, we show that the optimal stimulation times are non-uniform. Using the model of weakly pulse-coupled neurons with phase response curves, we provide an approach that enables to determine optimal stimulation timing patterns that substantially maximize the desynchronized transient time following the application of CR stimulation. This approach includes an optimization search for clusters in a low-dimensional pulse coupled map. As a consequence, model-specific non-uniformly spaced cluster states cause considerably longer desynchronization transients. Intriguingly, such a desynchronization boost with non-uniform CR stimulation can already be achieved by only slight modifications of the uniform CR timing pattern. Our results suggest that the non-uniformness of the stimulation times can be a medically valuable parameter in the calibration procedure for CR stimulation, where the latter has successfully been used in clinical and pre-clinical studies for the treatment of Parkinson's disease and tinnitus. PMID:23750134

  9. Instruction sequence based non-uniform complexity classes

    NARCIS (Netherlands)

    Bergstra, J.A.; Middelburg, C.A.

    2013-01-01

    We present an approach to non-uniform complexity in which single-pass instruction sequences play a key part, and answer various questions that arise from this approach. We introduce several kinds of non-uniform complexity classes. One kind includes a counterpart of the well-known non-uniform

  10. The large-s field-reversed configuration experiment

    International Nuclear Information System (INIS)

    Hoffman, A.L.; Carey, L.N.; Crawford, E.A.; Harding, D.G.; DeHart, T.E.; McDonald, K.F.; McNeil, J.L.; Milroy, R.D.; Slough, J.T.; Maqueda, R.; Wurden, G.A.

    1993-01-01

    The Large-s Experiment (LSX) was built to study the formation and equilibrium properties of field-reversed configurations (FRCs) as the scale size increases. The dynamic, field-reversed theta-pinch method of FRC creation produces axial and azimuthal deformations and makes formation difficult, especially in large devices with large s (number of internal gyroradii) where it is difficult to achieve initial plasma uniformity. However, with the proper technique, these formation distortions can be minimized and are then observed to decay with time. This suggests that the basic stability and robustness of FRCs formed, and in some cases translated, in smaller devices may also characterize larger FRCs. Elaborate formation controls were included on LSX to provide the initial uniformity and symmetry necessary to minimize formation disturbances, and stable FRCs could be formed up to the design goal of s = 8. For x ≤ 4, the formation distortions decayed away completely, resulting in symmetric equilibrium FRCs with record confinement times up to 0.5 ms, agreeing with previous empirical scaling laws (τ∝sR). Above s = 4, reasonably long-lived (up to 0.3 ms) configurations could still be formed, but the initial formation distortions were so large that they never completely decayed away, and the equilibrium confinement was degraded from the empirical expectations. The LSX was only operational for 1 yr, and it is not known whether s = 4 represents a fundamental limit for good confinement in simple (no ion beam stabilization) FRCs or whether it simply reflects a limit of present formation technology. Ideally, s could be increased through flux buildup from neutral beams. Since the addition of kinetic or beam ions will probably be desirable for heating, sustainment, and further stabilization of magnetohydrodynamic modes at reactor-level s values, neutral beam injection is the next logical step in FRC development. 24 refs., 21 figs., 2 tabs

  11. School Uniforms: Esprit de Corps.

    Science.gov (United States)

    Ryan, Rosemary P.; Ryan, Thomas E.

    1998-01-01

    The benefits of school uniforms far outweigh their short-term costs. School uniforms not only keep students safe, but they increase their self-esteem, promote a more positive attitude toward school, lead to improved student behavior, and help blur social-class distinctions. Students are allowed to wear their own political or religious messages,…

  12. Comments on Beckmann's Uniform Reducts

    OpenAIRE

    Cook, Stephen

    2006-01-01

    Arnold Beckmann defined the uniform reduct of a propositional proof system f to be the set of those bounded arithmetical formulas whose propositional translations have polynomial size f-proofs. We prove that the uniform reduct of f + Extended Frege consists of all true bounded arithmetical formulas iff f + Extended Frege simulates every proof system.

  13. Pellicle transmission uniformity requirements

    Science.gov (United States)

    Brown, Thomas L.; Ito, Kunihiro

    1998-12-01

    Controlling critical dimensions of devices is a constant battle for the photolithography engineer. Current DUV lithographic process exposure latitude is typically 12 to 15% of the total dose. A third of this exposure latitude budget may be used up by a variable related to masking that has not previously received much attention. The emphasis on pellicle transmission has been focused on increasing the average transmission. Much less, attention has been paid to transmission uniformity. This paper explores the total demand on the photospeed latitude budget, the causes of pellicle transmission nonuniformity and examines reasonable expectations for pellicle performance. Modeling is used to examine how the two primary errors in pellicle manufacturing contribute to nonuniformity in transmission. World-class pellicle transmission uniformity standards are discussed and a comparison made between specifications of other components in the photolithographic process. Specifications for other materials or parameters are used as benchmarks to develop a proposed industry standard for pellicle transmission uniformity.

  14. Evaluation of gafchromic EBT film for intensity modulated radiation therapy dose distribution verification

    International Nuclear Information System (INIS)

    Sankar, A.; Gopalkrishna Kurup, P.G.; Murali, V.; Ayyangar, Komanduri M.; Mothilal Nehru, R.; Velmurugan, J.

    2006-01-01

    This work was undertaken with the intention of investigating the possibility of clinical use of commercially available self-developing radiochromic film - Gafchromic EBT film - for IMRT dose verification. The dose response curves were generated for the films using VXR-16 film scanner. The results obtained with EBT films were compared with the results of Kodak EDR2 films. It was found that the EBT film has a linear response between the dose ranges of 0 and 600 cGy. The dose-related characteristics of the EBT film, like post-irradiation color growth with time, film uniformity and effect of scanning orientation, were studied. There is up to 8.6% increase in the color density between 2 and 40 h after irradiation. There was a considerable variation, up to 8.5%, in the film uniformity over its sensitive region. The quantitative difference between calculated and measured dose distributions was analyzed using Gamma index with the tolerance of 3% dose difference and 3 mm distance agreement. EDR2 films showed good and consistent results with the calculated dose distribution, whereas the results obtained using EBT were inconsistent. The variation in the film uniformity limits the use of EBT film for conventional large field IMRT verification. For IMRT of smaller field size (4.5 x 4.5 cm), the results obtained with EBT were comparable with results of EDR2 films. (author)

  15. Analyses of the Impact of School Uniforms on Violence in North Carolina Public High Schools

    Science.gov (United States)

    Johnson, Wesley Scott

    2010-01-01

    This study incorporated a multiple-methods design utilizing both quantitative and qualitative data. The quantitative portion investigated several annual reports distributed by the North Carolina Department of Public Instruction (NCDPI) to explore the impact of school uniform policies on incidents of crime and violence and occurrences of…

  16. A RICH with aerogel: a study of refractive index uniformity

    CERN Document Server

    Alemi, M; Calvi, M; Matteuzzi, C; Musy, M; Perego, D L; Easo, S

    2004-01-01

    The use of aerogel as a radiator in the RICH detectors of LHCb is a challenge due to the hot environment of the hadron collider LHC. Large size tiles of silica aerogel were recently produced with unprecedented optical quality for such dimensions. Results of laboratory measurements and beam tests are briefly reported. A description of a method to measure the uniformity of the index of refraction within the tile is given.

  17. Weak completeness of the Bourbaki quasi-uniformity

    Directory of Open Access Journals (Sweden)

    M.A. Sánchez Granero

    2001-04-01

    Full Text Available The concept of semicompleteness (weaker than half-completeness is defined for the Bourbaki quasi-uniformity of the hyperspace of a quasi-uniform space. It is proved that the Bourbaki quasi-uniformity is semicomplete in the space of nonempty sets of a quasi-uniform space (X,U if and only if each stable filter on (X,U* has a cluster point in (X,U. As a consequence the space of nonempty sets of a quasi-pseudometric space is semicomplete if and only if the space itself is half-complete. It is also given a characterization of semicompleteness of the space of nonempty U*-compact sets of a quasi-uniform space (X,U which extends the well known Zenor-Morita theorem.

  18. Test stand for non-uniformity correction of microbolometer focal plane arrays used in thermal cameras

    Science.gov (United States)

    Krupiński, Michał; Bareła, Jaroslaw; Firmanty, Krzysztof; Kastek, Mariusz

    2013-10-01

    Uneven response of particular detectors (pixels) to the same incident power of infrared radiation is an inherent feature of microbolometer focal plane arrays. As a result an image degradation occurs, known as Fixed Pattern Noise (FPN), which distorts the thermal representation of an observed scene and impairs the parameters of a thermal camera. In order to compensate such non-uniformity, several NUC correction methods are applied in digital data processing modules implemented in thermal cameras. Coefficients required to perform the non-uniformity correction procedure (NUC coefficients) are determined by calibrating the camera against uniform radiation sources (blackbodies). Non-uniformity correction is performed in a digital processing unit in order to remove FPN pattern in the registered thermal images. Relevant correction coefficients are calculated on the basis of recorded detector responses to several values of radiant flux emitted from reference IR radiation sources (blackbodies). The measurement of correction coefficients requires specialized setup, in which uniform, extended radiation sources with high temperature stability are one of key elements. Measurement stand for NUC correction developed in Institute of Optoelectronics, MUT, comprises two integrated extended blackbodies with the following specifications: area 200×200 mm, stabilized absolute temperature range +15 °C÷100 °C, and uniformity of temperature distribution across entire surface +/-0.014 °C. Test stand, method used for the measurement of NUC coefficients and the results obtained during the measurements conducted on a prototype thermal camera will be presented in the paper.

  19. Uniform illumination rendering using an array of LEDs: a signal processing perspective

    NARCIS (Netherlands)

    Yang, Hongming; Bergmans, J.W.M.; Schenk, T.C.W.; Linnartz, J.P.M.G.; Rietman, R.

    2009-01-01

    An array of a large number of LEDs will be widely used in future indoor illumination systems. In this paper, we investigate the problem of rendering uniform illumination by a regular LED array on the ceiling of a room. We first present two general results on the scaling property of the basic

  20. Large-scale spatial distribution patterns of gastropod assemblages in rocky shores.

    Directory of Open Access Journals (Sweden)

    Patricia Miloslavich

    Full Text Available Gastropod assemblages from nearshore rocky habitats were studied over large spatial scales to (1 describe broad-scale patterns in assemblage composition, including patterns by feeding modes, (2 identify latitudinal pattern of biodiversity, i.e., richness and abundance of gastropods and/or regional hotspots, and (3 identify potential environmental and anthropogenic drivers of these assemblages. Gastropods were sampled from 45 sites distributed within 12 Large Marine Ecosystem regions (LME following the NaGISA (Natural Geography in Shore Areas standard protocol (www.nagisa.coml.org. A total of 393 gastropod taxa from 87 families were collected. Eight of these families (9.2% appeared in four or more different LMEs. Among these, the Littorinidae was the most widely distributed (8 LMEs followed by the Trochidae and the Columbellidae (6 LMEs. In all regions, assemblages were dominated by few species, the most diverse and abundant of which were herbivores. No latitudinal gradients were evident in relation to species richness or densities among sampling sites. Highest diversity was found in the Mediterranean and in the Gulf of Alaska, while highest densities were found at different latitudes and represented by few species within one genus (e.g. Afrolittorina in the Agulhas Current, Littorina in the Scotian Shelf, and Lacuna in the Gulf of Alaska. No significant correlation was found between species composition and environmental variables (r≤0.355, p>0.05. Contributing variables to this low correlation included invasive species, inorganic pollution, SST anomalies, and chlorophyll-a anomalies. Despite data limitations in this study which restrict conclusions in a global context, this work represents the first effort to sample gastropod biodiversity on rocky shores using a standardized protocol across a wide scale. Our results will generate more work to build global databases allowing for large-scale diversity comparisons of rocky intertidal assemblages.

  1. Effect of transverse power distribution on the ONB location in the subcooled boiling flow

    International Nuclear Information System (INIS)

    Al-Yahia, Omar S.; Lee, Yong Joong; Jo, Daeseong

    2017-01-01

    Highlights: • Effect of transverse power distribution on ONB incipient. • Uniform and non-uniform heat distribution is simulated in a narrow rectangular channel. • Simulations are performed using CFX and TMAP codes. • For uniform heating, ONB incipient by CFX occurs between predictions by TMAP analyses. • For non-uniform heating, ONB incipient by CFX occurs at a higher power than that by TMAP analysis. - Abstract: This study investigates the effect of transverse power distribution on the ONB (Onset of Nucleate Boiling) incipient. For this purpose, a subcooled boiling model with uniform and non-uniform heat flux distribution is simulated in a narrow vertical rectangular channel heated from both sides by applying a wide range of thermal power (8–16 kW). The simulations are performed using the CFX and TMAP codes. The CFX code incorporates both a two-fluid model and RPI wall boiling model to investigate coolant and wall temperature distributions along the heated channel. The TMAP code implements two different sets of heat transfer correlations to evaluate the wall temperature. The results obtained from the TMAP analyses show that the wall temperatures predicted by the Jo et al. heat transfer correlation are higher than the ones predicted by the Dittus and Boelter heat transfer correlation. The wall temperatures predicted by the CFX analyses lie between the predicted wall temperatures obtained by the TMAP analyses. Based on the superheated temperature on the heated surface, the ONB incipient is determined. The axial locations of the ONB incipient are predicted differently by the CFX and TMAP analyses. For uniform heating, the ONB incipient predicted by the CFX analysis occurs between the predictions made by the TMAP analyses. For non-uniform heating, the ONB incipient by the CFX analysis occurs at a higher power than the power required by the TMAP analyses.

  2. Mesoporous Silica Thin Membranes with Large Vertical Mesochannels for Nanosize-Based Separation.

    Science.gov (United States)

    Liu, Yupu; Shen, Dengke; Chen, Gang; Elzatahry, Ahmed A; Pal, Manas; Zhu, Hongwei; Wu, Longlong; Lin, Jianjian; Al-Dahyan, Daifallah; Li, Wei; Zhao, Dongyuan

    2017-09-01

    Membrane separation technologies are of great interest in industrial processes such as water purification, gas separation, and materials synthesis. However, commercial filtration membranes have broad pore size distributions, leading to poor size cutoff properties. In this work, mesoporous silica thin membranes with uniform and large vertical mesochannels are synthesized via a simple biphase stratification growth method, which possess an intact structure over centimeter size, ultrathin thickness (≤50 nm), high surface areas (up to 1420 m 2 g -1 ), and tunable pore sizes from ≈2.8 to 11.8 nm by adjusting the micelle parameters. The nanofilter devices based on the free-standing mesoporous silica thin membranes show excellent performances in separating differently sized gold nanoparticles (>91.8%) and proteins (>93.1%) due to the uniform pore channels. This work paves a promising way to develop new membranes with well-defined pore diameters for highly efficient nanosize-based separation at the macroscale. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Large Scale Behavior and Droplet Size Distributions in Crude Oil Jets and Plumes

    Science.gov (United States)

    Katz, Joseph; Murphy, David; Morra, David

    2013-11-01

    The 2010 Deepwater Horizon blowout introduced several million barrels of crude oil into the Gulf of Mexico. Injected initially as a turbulent jet containing crude oil and gas, the spill caused formation of a subsurface plume stretching for tens of miles. The behavior of such buoyant multiphase plumes depends on several factors, such as the oil droplet and bubble size distributions, current speed, and ambient stratification. While large droplets quickly rise to the surface, fine ones together with entrained seawater form intrusion layers. Many elements of the physics of droplet formation by an immiscible turbulent jet and their resulting size distribution have not been elucidated, but are known to be significantly influenced by the addition of dispersants, which vary the Weber Number by orders of magnitude. We present experimental high speed visualizations of turbulent jets of sweet petroleum crude oil (MC 252) premixed with Corexit 9500A dispersant at various dispersant to oil ratios. Observations were conducted in a 0.9 m × 0.9 m × 2.5 m towing tank, where large-scale behavior of the jet, both stationary and towed at various speeds to simulate cross-flow, have been recorded at high speed. Preliminary data on oil droplet size and spatial distributions were also measured using a videoscope and pulsed light sheet. Sponsored by Gulf of Mexico Research Initiative (GoMRI).

  4. Decomposing wage distributions on a large data set - a quantile regression analysis of the gender wage gap

    DEFF Research Database (Denmark)

    Albæk, Karsten; Brink Thomsen, Lars

    This paper presents and implements a procedure that makes it possible to decompose wage distributions on large data sets. We replace bootstrap sampling in the standard Machado-Mata procedure with ‘non-replacement subsampling’, which is more suitable for the linked employer-employee data applied i...... in gender wage differences in the lower part of the wage distribution.......This paper presents and implements a procedure that makes it possible to decompose wage distributions on large data sets. We replace bootstrap sampling in the standard Machado-Mata procedure with ‘non-replacement subsampling’, which is more suitable for the linked employer-employee data applied...... in this paper. Decompositions show that most of the glass ceiling is related to segregation in the form of either composition effects or different returns to males and females. A counterfactual wage distribution without differences in the constant terms (or ‘discrimination’) implies substantial changes...

  5. 46 CFR 310.63 - Uniforms and textbooks.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 8 2010-10-01 2010-10-01 false Uniforms and textbooks. 310.63 Section 310.63 Shipping MARITIME ADMINISTRATION, DEPARTMENT OF TRANSPORTATION TRAINING MERCHANT MARINE TRAINING Admission and Training of Midshipmen at the United States Merchant Marine Academy § 310.63 Uniforms and textbooks. The Academy shall supply midshipmen uniforms an...

  6. Uniform-droplet spray forming

    Energy Technology Data Exchange (ETDEWEB)

    Blue, C.A.; Sikka, V.K. [Oak Ridge National Lab., TN (United States); Chun, Jung-Hoon [Massachusetts Institute of Technology, Cambridge, MA (United States); Ando, T. [Tufts Univ., Medford, MA (United States)

    1997-04-01

    The uniform-droplet process is a new method of liquid-metal atomization that results in single droplets that can be used to produce mono-size powders or sprayed-on to substrates to produce near-net shapes with tailored microstructure. The mono-sized powder-production capability of the uniform-droplet process also has the potential of permitting engineered powder blends to produce components of controlled porosity. Metal and alloy powders are commercially produced by at least three different methods: gas atomization, water atomization, and rotating disk. All three methods produce powders of a broad range in size with a very small yield of fine powders with single-sized droplets that can be used to produce mono-size powders or sprayed-on substrates to produce near-net shapes with tailored microstructures. The economical analysis has shown the process to have the potential of reducing capital cost by 50% and operating cost by 37.5% when applied to powder making. For the spray-forming process, a 25% savings is expected in both the capital and operating costs. The project is jointly carried out at Massachusetts Institute of Technology (MIT), Tuffs University, and Oak Ridge National Laboratory (ORNL). Preliminary interactions with both finished parts and powder producers have shown a strong interest in the uniform-droplet process. Systematic studies are being conducted to optimize the process parameters, understand the solidification of droplets and spray deposits, and develop a uniform-droplet-system (UDS) apparatus appropriate for processing engineering alloys.

  7. Spatially-explicit estimation of geographical representation in large-scale species distribution datasets.

    Science.gov (United States)

    Kalwij, Jesse M; Robertson, Mark P; Ronk, Argo; Zobel, Martin; Pärtel, Meelis

    2014-01-01

    Much ecological research relies on existing multispecies distribution datasets. Such datasets, however, can vary considerably in quality, extent, resolution or taxonomic coverage. We provide a framework for a spatially-explicit evaluation of geographical representation within large-scale species distribution datasets, using the comparison of an occurrence atlas with a range atlas dataset as a working example. Specifically, we compared occurrence maps for 3773 taxa from the widely-used Atlas Florae Europaeae (AFE) with digitised range maps for 2049 taxa of the lesser-known Atlas of North European Vascular Plants. We calculated the level of agreement at a 50-km spatial resolution using average latitudinal and longitudinal species range, and area of occupancy. Agreement in species distribution was calculated and mapped using Jaccard similarity index and a reduced major axis (RMA) regression analysis of species richness between the entire atlases (5221 taxa in total) and between co-occurring species (601 taxa). We found no difference in distribution ranges or in the area of occupancy frequency distribution, indicating that atlases were sufficiently overlapping for a valid comparison. The similarity index map showed high levels of agreement for central, western, and northern Europe. The RMA regression confirmed that geographical representation of AFE was low in areas with a sparse data recording history (e.g., Russia, Belarus and the Ukraine). For co-occurring species in south-eastern Europe, however, the Atlas of North European Vascular Plants showed remarkably higher richness estimations. Geographical representation of atlas data can be much more heterogeneous than often assumed. Level of agreement between datasets can be used to evaluate geographical representation within datasets. Merging atlases into a single dataset is worthwhile in spite of methodological differences, and helps to fill gaps in our knowledge of species distribution ranges. Species distribution

  8. Economic Model Predictive Control for Large-Scale and Distributed Energy Systems

    DEFF Research Database (Denmark)

    Standardi, Laura

    Sources (RESs) in the smart grids is increasing. These energy sources bring uncertainty to the production due to their fluctuations. Hence,smart grids need suitable control systems that are able to continuously balance power production and consumption.  We apply the Economic Model Predictive Control (EMPC......) strategy to optimise the economic performances of the energy systems and to balance the power production and consumption. In the case of large-scale energy systems, the electrical grid connects a high number of power units. Because of this, the related control problem involves a high number of variables......In this thesis, we consider control strategies for large and distributed energy systems that are important for the implementation of smart grid technologies.  An electrical grid has to ensure reliability and avoid long-term interruptions in the power supply. Moreover, the share of Renewable Energy...

  9. The depth distribution of bubbles and fracture in He+ and D+ irradiated copper

    International Nuclear Information System (INIS)

    Johnson, P.B.; Mazey, D.J.

    1982-01-01

    Transmission electron microscopy is used to investigate the spatial arrangement and distribution with depth of gas bubbles produced in Cu by irradiation at 320 K to a level approx. equal to 4 x 10 21 30 keV He + m -2 . At the depth of maximum bubble size the bubbles are random and large (up to approx. equal to 10 nm across). At both shallower and greater depths the gas bubbles are smaller (approx. equal to 2 nm diam), much more uniform in size and ordered on an fcc superlattice with a lattice constant of a 1 approx. equal to 7.7 nm which (in contrast to the average bubble size) is independent of depth. It is suggested that blistering results from fracture, at a depth near the mean projected range, between large randomly-ordered bubbles which have evolved from smaller bubbles of uniform size arranged on a superlattice. For the particular case of D + irradiation of Cu at 120 K evidence is found to suggest that the fracture mechanisms involved in blistering and flaking are quite different. (orig.)

  10. OSSOS. VI. Striking Biases in the Detection of Large Semimajor Axis Trans-Neptunian Objects

    Science.gov (United States)

    Shankman, Cory; Kavelaars, J. J.; Bannister, Michele T.; Gladman, Brett J.; Lawler, Samantha M.; Chen, Ying-Tung; Jakubik, Marian; Kaib, Nathan; Alexandersen, Mike; Gwyn, Stephen D. J.; Petit, Jean-Marc; Volk, Kathryn

    2017-08-01

    The accumulating but small set of large semimajor axis trans-Neptunian objects (TNOs) shows an apparent clustering in the orientations of their orbits. This clustering must either be representative of the intrinsic distribution of these TNOs, or else have arisen as a result of observation biases and/or statistically expected variations for such a small set of detected objects. The clustered TNOs were detected across different and independent surveys, which has led to claims that the detections are therefore free of observational bias. This apparent clustering has led to the so-called “Planet 9” hypothesis that a super-Earth currently resides in the distant solar system and causes this clustering. The Outer Solar System Origins Survey (OSSOS) is a large program that ran on the Canada–France–Hawaii Telescope from 2013 to 2017, discovering more than 800 new TNOs. One of the primary design goals of OSSOS was the careful determination of observational biases that would manifest within the detected sample. We demonstrate the striking and non-intuitive biases that exist for the detection of TNOs with large semimajor axes. The eight large semimajor axis OSSOS detections are an independent data set, of comparable size to the conglomerate samples used in previous studies. We conclude that the orbital distribution of the OSSOS sample is consistent with being detected from a uniform underlying angular distribution.

  11. Uniform Single Valued Neutrosophic Graphs

    Directory of Open Access Journals (Sweden)

    S. Broumi

    2017-09-01

    Full Text Available In this paper, we propose a new concept named the uniform single valued neutrosophic graph. An illustrative example and some properties are examined. Next, we develop an algorithmic approach for computing the complement of the single valued neutrosophic graph. A numerical example is demonstrated for computing the complement of single valued neutrosophic graphs and uniform single valued neutrosophic graph.

  12. A Local Asynchronous Distributed Privacy Preserving Feature Selection Algorithm for Large Peer-to-Peer Networks

    Data.gov (United States)

    National Aeronautics and Space Administration — In this paper we develop a local distributed privacy preserving algorithm for feature selection in a large peer-to-peer environment. Feature selection is often used...

  13. Uniformidade de distribuição do potássio e do nitrogênio em sistema de irrigação por gotejamento Evaluation of potassium and nitrogen distribution uniformity in trickle irrigation system

    Directory of Open Access Journals (Sweden)

    Marcus V. A. M. de Oliveira

    2008-03-01

    Full Text Available O uso da fertirrigação possibilita a obtenção de bons resultados, todavia é notada a necessidade de trabalhos que venham possibilitar a adoção correta da técnica. Dessa forma ,o presente trabalho buscou comparar a uniformidade de distribuição do potássio e do nitrogênio em sistema de irrigação por gotejamento. A solução de fertilizantes foi injetada durante 25 minutos, sendo recolhidas amostras de solução em diferentes momentos, durante e após ter sido finalizada a operação de injeção, tendo sido especificado o tempo de 35 minutos após o início da operação de injeção da solução de fertilizantes, como tempo-limite para a coleta da última amostra. As amostras coletadas tiveram os teores de potássio (K+ e nitrogênio (NO3- + NH4+ determinados. Com os resultados obtidos, concluiu-se que não houve variação significativa da uniformidade de distribuição de nitrogênio e de potássio no sistema de irrigação por gotejamento; maiores tempos de funcionamento de sistemas de irrigação, quando em operação de fertirrigação, possibilitam melhores uniformidades de distribuição do fertilizante, e deve-se calcular o tempo de lavagem do sistema de irrigação, pois é uma forma de melhorar a uniformidade de distribuição do fertilizante no campo.The use of the fertigation makes possible obtaining good results; however it was noticed the necessity of studies that make possible the correct adoption of this technique. Thus the present study aimed to compare the distribution uniformity of potassium and nitrogen when applied through a trickle irrigation system. The fertilizers solution was applied during 25 minutes; samples of solution were collected at different moments during and after the product injection through irrigation water, and the time limit to collect the last sample was specified as 35 minutes after injection operations begun. In the collected samples were determined the contents of potassium (K+ and

  14. Sun protection provided by regulation school uniforms in Australian schools: an opportunity to improve personal sun protection during childhood.

    Science.gov (United States)

    Turner, Denise; Harrison, Simone L

    2014-01-01

    Childhood sun exposure is linked to excessive pigmented mole development and melanoma risk. Clothing provides a physical barrier, protecting skin from ultraviolet radiation (UVR). Extending sleeves to elbow length and shorts to knee length has been shown to significantly reduce mole acquisition in preschoolers from tropical Queensland. We used publicly available uniform images and guidelines from primary schools in Townsville (latitude 19.25°S, n = 43 schools), Cairns (16.87°S, n = 46) and the Atherton Tablelands (17.26°S, n = 23) in tropical Australia to objectively determine the body surface proportion covered by regulation school uniforms. Uniforms of nongovernment, large (≥800 students), urban, educationally advantaged schools with comprehensive sun protection policies covered more skin than those of government schools (63.2% vs 62.0%; P schools (63.4% vs 62.3%; P = 0.009), rural (62.7% vs 61.9%; P = 0.002) and educationally disadvantaged schools (62.8% vs 62.3%; P school uniforms covered identical body surface proportions (62.4%, P = 0.084). Although wearing regulation school uniforms is mandatory at most Australian primary schools, this opportunity to improve children's sun protection is largely overlooked. Recent evidence suggests that even encouraging minor alterations to school uniforms (e.g. slightly longer sleeves/dresses/skirts/shorts) to increase skin coverage may reduce mole acquisition and melanoma risk, especially in high-risk populations. © 2014 The American Society of Photobiology.

  15. The Large Scale Distribution of Water Ice in the Polar Regions of the Moon

    Science.gov (United States)

    Jordan, A.; Wilson, J. K.; Schwadron, N.; Spence, H. E.

    2017-12-01

    For in situ resource utilization, one must know where water ice is on the Moon. Many datasets have revealed both surface deposits of water ice and subsurface deposits of hydrogen near the lunar poles, but it has proved difficult to resolve the differences among the locations of these deposits. Despite these datasets disagreeing on how deposits are distributed on small scales, we show that most of these datasets do agree on the large scale distribution of water ice. We present data from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO), LRO's Lunar Exploration Neutron Detector (LEND), the Neutron Spectrometer on Lunar Prospector (LPNS), LRO's Lyman Alpha Mapping Project (LAMP), LRO's Lunar Orbiter Laser Altimeter (LOLA), and Chandrayaan-1's Moon Mineralogy Mapper (M3). All, including those that show clear evidence for water ice, reveal surprisingly similar trends with latitude, suggesting that both surface and subsurface datasets are measuring ice. All show that water ice increases towards the poles, and most demonstrate that its signature appears at about ±70° latitude and increases poleward. This is consistent with simulations of how surface and subsurface cold traps are distributed with latitude. This large scale agreement constrains the origin of the ice, suggesting that an ancient cometary impact (or impacts) created a large scale deposit that has been rendered locally heterogeneous by subsequent impacts. Furthermore, it also shows that water ice may be available down to ±70°—latitudes that are more accessible than the poles for landing.

  16. TDM/FM/FDMA - A modulation technique for multiple-beam satellites which precludes cochannel interference and allows non-uniform geographic distribution of user channels

    Science.gov (United States)

    Springett, J. C.

    1982-01-01

    The technique outlined in this paper is intended to eliminate the problems of cochannel interference and uniform geographic distribution of user channels which arise in conventional designs for a multiple spot beam communication satellite to serve mobile telephony users across the CONUS. By time multiplexing FM/FDMA signal ensembles so that only those beams operating on distinct frequency subbands are allowed to transmit concurrently, cochannel interference arising from simultaneous frequency subband reuse is precluded. Thus, time disjoint frequency reuse is accomplished over a repetitive sequence of fixed time slots. By assigning different size subbands to each time slot, a market of nonuniform users can be accommodated. The technique results in a greatly simplified antenna feed system design for the satellite, at a cost of imposing the need for time slot synchronization on the mobile FM receivers whose ability for rejecting adjacent channel interference is somewhat diminished.

  17. TDM/FM/FDMA - A modulation technique for multiple-beam satellites which precludes cochannel interference and allows non-uniform geographic distribution of user channels

    Science.gov (United States)

    Springett, J. C.

    The technique outlined in this paper is intended to eliminate the problems of cochannel interference and uniform geographic distribution of user channels which arise in conventional designs for a multiple spot beam communication satellite to serve mobile telephony users across the CONUS. By time multiplexing FM/FDMA signal ensembles so that only those beams operating on distinct frequency subbands are allowed to transmit concurrently, cochannel interference arising from simultaneous frequency subband reuse is precluded. Thus, time disjoint frequency reuse is accomplished over a repetitive sequence of fixed time slots. By assigning different size subbands to each time slot, a market of nonuniform users can be accommodated. The technique results in a greatly simplified antenna feed system design for the satellite, at a cost of imposing the need for time slot synchronization on the mobile FM receivers whose ability for rejecting adjacent channel interference is somewhat diminished.

  18. Dynamic thermoelectricity in uniform bipolar semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Volovichev, I.N., E-mail: vin@ire.kharkov.ua

    2016-07-01

    The theory of the dynamic thermoelectric effect has been developed. The effect lies in an electric current flowing in a closed circuit that consists of a uniform bipolar semiconductor, in which a non-uniform temperature distribution in the form of the traveling wave is created. The calculations are performed for the one-dimensional model in the quasi-neutrality approximation. It was shown that the direct thermoelectric current prevails, despite the periodicity of the thermal excitation, the circuit homogeneity and the lack of rectifier properties of the semiconductor system. Several physical reasons underlining the dynamic thermoelectric effect are found. One of them is similar to the Dember photoelectric effect, its contribution to the current flowing is determined by the difference in the electron and hole mobilities, and is completely independent of the carrier Seebeck coefficients. The dependence of the thermoelectric short circuit current magnitude on the semiconductor parameters, as well as on the temperature wave amplitude, length and velocity is studied. It is shown that the magnitude of the thermoelectric current is proportional to the square of the temperature wave amplitude. The dependence of the thermoelectric short circuit current on the temperature wave length and velocity is the nonmonotonic function. The optimum values for the temperature wave length and velocity, at which the dynamic thermoelectric effect is the greatest, have been deduced. It is found that the thermoelectric short circuit current changes its direction with decreasing the temperature wave length under certain conditions. The prospects for the possible applications of the dynamic thermoelectric effect are also discussed.

  19. The Proposal of Scaling the Roles in Scrum of Scrums for Distributed Large Projects

    OpenAIRE

    Abeer M. AlMutairi; M. Rizwan Jameel Qureshi

    2015-01-01

    Scrum of scrums is an approach used to scale the traditional Scrum methodology to fit for the development of complex and large projects. However, scaling the roles of scrum members brought new challenges especially in distributed and large software projects. This paper describes in details the roles of each scrum member in scrum of scrum to propose a solution to use a dedicated product owner for a team and inclusion of sub-backlog. The main goal of the proposed solution i...

  20. Architecture for large-scale automatic web accessibility evaluation based on the UWEM methodology

    DEFF Research Database (Denmark)

    Ulltveit-Moe, Nils; Olsen, Morten Goodwin; Pillai, Anand B.

    2008-01-01

    The European Internet Accessibility project (EIAO) has developed an Observatory for performing large scale automatic web accessibility evaluations of public sector web sites in Europe. The architecture includes a distributed web crawler that crawls web sites for links until either a given budget...... of web pages have been identified or the web site has been crawled exhaustively. Subsequently, a uniform random subset of the crawled web pages is sampled and sent for accessibility evaluation and the evaluation results are stored in a Resource Description Format (RDF) database that is later loaded...... challenges that the project faced and the solutions developed towards building a system capable of regular large-scale accessibility evaluations with sufficient capacity and stability. It also outlines some possible future architectural improvements....