Hasil untuk "cond-mat.other"

B. Kilbride, J. Coleman, J. Fraysse et al.

Alternating current (ac) and direct current (dc) conductivities have been measured in polymer-nanotube composite thin films. This was carried out for a range of concentrations of multiwall nanotubes in two polymer hosts, poly(m-phenylenevinylene-co-2,5-dioctyloxyp-phenylenevinylene) (PmPV) and polyvinylalcohol (PVA). In all cases the dc conductivity σDC was ohmic in the voltage range studied. In general the ac conductivity displayed two distinct regions, a frequency independent region of magnitude σ0 at low frequency and a frequency dependent region at higher frequency. Both σDC and σ0 followed a percolation scaling law of the form σ∝(p−pc)t with pc=0.055% by mass and t=1.36. This extrapolates to a conductivity of 1×10−3 S/m for 100% nanotube content. Such a low value reflects the presence of a thick polymer coating, resulting in poor electrical connection between tubes. This leads to the suggestion that charge transport is controlled by fluctuation induced tunneling. In the high frequency regime the cond...

L. A. Melnikovsky

Andreev-Bashkin entrainment makes the hydrodynamics of the binary superfluid solution particularly interesting. We investigate stability and motion of quantum vortices in such system.

Dario Stein, S. Staton

We define a probabilistic programming language for Gaussian random variables with a first-class exact conditioning construct. We give operational, denotational and equational semantics for this language, establishing convenient properties like exchangeability of conditions. Conditioning on equality of continuous random variables is nontrivial, as the exact observation may have probability zero; this is Borel’s paradox. Using categorical formulations of conditional probability, we show that the good properties of our language are not particular to Gaussians, but can be derived from universal properties, thus generalizing to wider settings. We define the Cond construction, which internalizes conditioning as a morphism, providing general compositional semantics for probabilistic programming with exact conditioning.

Graham Macdonald, M. Penney, Michelle E. Mullaley et al.

J. Brazier, M. Antrobus, G. Stebbings et al.

Brazier, J, Antrobus, M, Stebbings, GK, Day, SH, Callus, P, Erskine, RM, Bennett, MA, Kilduff, LP, and Williams, AG. Anthropometric and physiological characteristics of elite male rugby athletes. J Strength Cond Res XX(X): 000-000, 2018-This is the first article to review the anthropometric and physiological characteristics required for elite rugby performance within both rugby union (RU) and rugby league (RL). Anthropometric characteristics such as height and body mass, and physiological characteristics such as speed and muscular strength, have previously been advocated as key discriminators of playing level within rugby. This review aimed to identify the key anthropometric and physiological properties required for elite performance in rugby, distinguishing between RU and RL, forwards and backs and competitive levels. There are differences between competitive standards such that, at the elite level, athletes are heaviest (RU forwards ∼111 kg, backs ∼93 kg; RL forwards ∼103 kg, backs ∼90 kg) with lowest % body fat (RU forwards ∼15%, backs ∼12%; RL forwards ∼14%, backs ∼11%), they have most fat-free mass and are strongest (back squat: RU forwards ∼176 kg, backs ∼157 kg; RL forwards ∼188 kg, backs ∼168 kg; bench press: RU forwards ∼131 kg, backs ∼118 kg; RL forwards ∼122 kg, backs ∼113 kg) and fastest (10 m: RU forwards ∼1.87 seconds, backs ∼1.77 seconds; 10 m: RL forwards ∼1.9 seconds, backs ∼1.83 seconds). We also have unpublished data that indicate contemporary RU athletes have less body fat and are stronger and faster than the published data suggest. Regardless, well-developed speed, agility, lower-body power, and strength characteristics are vital for elite performance, probably reflect both environmental (training, diet, etc.) and genetic factors, distinguish between competitive levels, and are therefore important determinants of elite status in rugby.

R. Gathercole, B. Sporer, T. Stellingwerff et al.

Abdelaziz Hakimi, H. Hamdi

Unal Yilmaz, Omer Turksoy, A. Teke

Abstract The changes in temperature and radiation cause visible fluctuations in the output power produced by the photovoltaic (PV) panels. It is essential to keep the output voltage of the PV panel at the maximum power point (MPP) under varying temperature and radiation conditions. In this study, a maximum power point tracking (MPPT) method has been developed which is based on mainly two parts: the first part is adapting calculation block for the reference voltage point of MPPT and the second one is Fuzzy Logic Controller (FLC) block to adjust the duty cycle of PWM applied switch (Mosfet) of the DC-DC converter. In order to evaluate the robustness of the proposed method, Matlab/Simulink program has been used to compare with the traditional methods which are Perturb & Observe (P&O), Incremental Conductance (Inc. Cond.) and FLC methods under variable atmospheric conditions. When the test results are observed, it is clearly obtained that the proposed MPPT method provides an increase in the tracking capability of MPP and at the same time reduced steady state oscillations. The accuracy of the proposed method is between 99.5% and 99.9%. In addition, the time to capture MPP is 0.021 sec. It is about four times faster than P&O and five times faster than for Inc. Cond. and, furthermore, the proposed method has been compared with the conventional FLC method and it has been observed that the proposed method is faster about 28% and also its efficiency is about 1% better than FLC method.

Rodrigo Ramirez-Campillo, Francisco Gallardo, C. Henríquez-Olguín et al.

N. Owen, J. Watkins, L. Kilduff et al.

K. Healey, D. Hatfield, P. Blanpied et al.

G. Laffaye, P. Wagner, Tom Tombleson

Marcus J. Colby, B. Dawson, J. Heasman et al.

Li-Chuan Jia, Dingxiang Yan, Xin (Cindy) Jiang et al.

Herein, the graphite–carbon nanotube (G-CNT) hybrid loaded ultrahigh molecular weight polyethylene (UHMWPE) composite with a segregated structure was fabricated. In such structure, the G-CNT hybrid was selectively distributed at the interfaces of UHMWPE domains to form interconnected networks, as demonstrated by optical microscopy and scanning electron microscopy. The resultant G-CNT/UHMWPE composite exhibited an excellent electrical conductivity of 195.3 S m–1 and an ultrahigh electromagnetic interference shielding effectiveness (EMI SE) of 81.0 dB. The results were superior to those of single graphite or the CNT loaded one, clearly confirming the synergistic effect of graphite and CNT. Amazingly, only a specimen of 0.5 mm thickness imparted the G-CNT/UHMWPE composite with an EMI SE of 31.8 dB, already matching the requirement for commercial EMI shielding applications. This work highlights the merit of integrating the segregated structure with the synergistic effect of G-CNT hybrid in forming highly cond...

M. Hammami, Y. Negra, F. Billaut et al.

Y. Hsu, C. Chiu, Yen-Peng Li et al.

C. Bishop, A. Turner, Paul Jarvis et al.

J. Courel-Ibáñez, B. J. Sánchez-Alcaraz Martínez, D. Muñoz Marín

Courel-Ibáñez, J, Sánchez-Alcaraz Martinez, BJ, and Muñoz Marín, D. Exploring game dynamics in padel: implications for assessment and training. J Strength Cond Res 33(7): 1971-1977, 2019-A better understanding of in-game competition demands potentially improved coaching strategy and quality. However, there is very limited information about game patterns in padel, a very modern racket sport born in the 70s. The purpose of this study was therefore to quantify and classify game dynamics during the match in professional padel players through a multivariate decision tree approach including technical, spatial, and effectiveness indicators. The results determined 3 main game styles strongly defined by the court zone (net, middle, and baseline). In addition, particular technical, spatial, and effectiveness indicators were identified in each zone. In net and middle areas (offense) stood the use of volleys and overhead strokes on the center lane to both keep a positional advantage and solve the point. Conversely in the baseline (defense), the use of corner side walls and the domain of lobs showed to be relevant. The high rate of backhand groundstrokes, involving over 4 of 10 actions, is also remarkable. This information may have relevant implications for coaches working in padel by providing a novel hierarchically organization of game dynamics, which helps in designing training and conditioning programs close to real competitive situations.

R. Orr, J. Dawes, J. Dawes et al.

Abstract Orr, RM, Dawes, JJ, Pope, R, and Terry, J. Assessing differences in anthropometric and fitness characteristics between police academy cadets and incumbent officers. J Strength Cond Res 32(9): 2641–2650, 2018—The physical fitness of police officers must be developed in new cadets and sustained in incumbent officers. The aims of this study were to profile and compare the anthropometric and fitness characteristics of police academy cadets and incumbent officers of varying ages from a single police force. Retrospective data for 84 police academy cadets (♂ = 66, mean age = 27.96 ± 5.73 years; ♀ = 18, mean age = 30.50 ± 5.76 years) and 80 incumbent police officers (♂ = 73, mean age = 39.43 ± 8.28 years; ♀ = 7, mean age = 37.86 ± 3.67 years) were compiled. Data included participant age, anthropometric (body mass, lean mass, and fat mass), and fitness measurements (1-minute push-up, 1-minute sit-up, 1 repetition maximum bench press, vertical jump, 300-m, and 1.5-mile run). Male cadets exhibited significantly lower fat mass than male officers (12.4 vs. 15.1 kg, p = 0.003). These differences were fully explained by the age differences between these groups (p = 0.046). Male cadets were more aerobically fit with greater muscular endurance than male officers (p 0.80 for all measures). Male cadets also exhibited higher anaerobic fitness than male officers (p < 0.001). Age differences only partially explained this difference (p = 0.01). Female cadets exhibited greater upper-body strength and muscular endurance than female officers (p < 0.004 for all measures), independent of age. Being a police officer, rather than age progression, may largely account for observed lower levels of fitness in incumbent officers when compared with cadets. Formalized physical training programs for incumbent police officers are needed if their fitness is to be maintained and risk of cardiovascular disease minimized.

D. Conte, Terence G. Favero, C. Lupo et al.