999 resultados para Christison, Wenlock, d. 1679?


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数字、量化、量化效应、模拟、模拟量、A/D换、D/A转换是计算机控制工程和控制理论上的常见概念。静心推敲,发现有不少流行性的误解。例如:不是“量化”而是截尾或四舍五入,不是“数字量”而是bit量,不是“模拟量”而是物理量等。

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介绍了用韧致辐射能谱测量高频 D压方法及测量结果。此方法的优点在于不受高频频率、主磁场及分布参数的影响

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利用强流低能氘离子束轰击由吸氢金属形成的氘自吸收靶,研究固体内D-D聚变反应规律。并通过对实验测得的D-D聚变伴随粒子能谱,探索D-D聚变反应与靶材料结构的相关性。同时,利用氘团族离子(d3+)和氘核(d+)来轰击吸氘固体,研究固体内D-D聚变反应的特性。实验中观测到了伴随离子能谱中介于质子峰(3MeV)和氚峰(1MeV)之间的一个宽峰。结果分析表明。该峰是由固体靶内超出离子射程几倍至十几倍处发生的D-D聚变反应出射的质子所形成。同时还发现独立氘核产生的这种深部D-D核聚变的反应率高于速度相同的氘团簇离子中的氘核的反应率。

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The N ∗(1535) resonance contributions to the pn → d reaction are evaluated in an effective Lagrangian model. The π-, η-, and ρ-meson exchange are considered. It is shown that the contributions from π- and ρ-meson exchange are dominant, while the contribution from η-meson exchange is negligibly small. Our theoretical results reproduce the experimental data of both total cross section and angular distribution well. This is more evidence that the N ∗(1535) resonance has a large s ¯s component leading to a large coupling to Nφ, which may be the real origin of the Okubo-Zweig-Iizuka rule violation in the πN and pN reactions.

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The real-space recursion method and unrestricted Hartree-Fock approximation have been applied to calculate the density of states of various Co perovskite, CeCoO3, SrCoO3 and Sr1-xCexCoO3. We have studied the magnetically ordered states of these Co perovskites in an enlarged double cell, and find its various magnetic structures due to the occupancy of 3d band and its interaction with neighboring Co ions. In this study, we have studied the p-d hybridization of the three Co perovskites, we find t(2g) electrons are localized and the flat e(g) band is responsible for the itinerant behavior, and although the rare earth elements itself contribute little to the DOS at the Fermi energy, the DOS at Fermi energy and the magnetic moment changed consequently because of different valence of Co ions in these compounds and p-d hybridization effect is very important. (C) 2009 Elsevier B.V. All rights reserved.

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In an effective Lagrangian model we find that the N*(1535) resonance contribution might be important to the interpretation of the present data of the pp -> pp eta' and pn -> d phi reactions. The strong coupling strength of N*(1.535) to eta' and phi are indicated, and the possible implication to the intrinsic component of N*(1535) is explored. These results may provide hints to the real origin of the OZI rule violation. It is stressed that further measurements could be performed at the Cooling Storage Ring (CSR) at Lanzhou of China.

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In this work, we systematically study the interaction of D* and nucleon, which is stimulated by the observation of Lambda(c)(2940)(+) close to the threshold of D* p. Our numerical result obtained by the dynamical investigation indicates the existence of the D* N systems with J(P) = 1/2(+/-), 3/2(+/-), which not only provides valuable information to understand the underlying structure of Lambda(c)(2940)(+) but also improves our knowledge of the interaction of D* and nucleon. Additionally, the bottom partners of the D* N systems are predicted, which might be as one of the tasks in LHCb experiment.

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Single-neutron-transfer measurements using (p,d) reactions have been performed at 33 MeV per nucleon with proton-rich Ar-34 and neutron-rich Ar-46 beams in inverse kinematics. The extracted spectroscopic factors are compared to the large-basis shell-model calculations. Relatively weak quenching of the spectroscopic factors is observed between Ar-34 and Ar-46. The experimental results suggest that neutron correlations have a weak dependence on the asymmetry of the nucleus over this isotopic region. The present results are consistent with the systematics established from extensive studies of spectroscopic factors and dispersive optical-model analyses of Ca40-49 isotopes. They are, however, inconsistent with the trends obtained in knockout-reaction measurements.

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Yields, correlation shapes, and mean transverse momenta p(T) of charged particles associated with intermediate-to high-p(T) trigger particles (2.5 < p(T) < 10 GeV/c) in d + Au and Au + Au collisions at root s(NN) = 200 GeV are presented. For associated particles at higher p(T) greater than or similar to 2.5 GeV/c, narrow correlation peaks are seen in d + Au and Au + Au, indicating that the main production mechanism is jet fragmentation. At lower associated particle pT < 2 GeV/c, a large enhancement of the near- (Delta phi similar to 0) and away-side (Delta phi similar to pi) associated yields is found, together with a strong broadening of the away-side azimuthal distributions in Au + Au collisions compared to d + Au measurements, suggesting that other particle production mechanisms play a role. This is further supported by the observed significant softening of the away-side associated particle yield distribution at Delta phi similar to pi in central Au + Au collisions.

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Balance functions have been measured for charged-particle pairs, identified charged-pion pairs, and identified charged-kaon pairs in Au + Au, d + Au, and p + p collisions at root s(NN) = 200 GeV at the Relativistic Heavy Ion Collider using the STAR detector. These balance functions are presented in terms of relative pseudorapidity, Delta eta, relative rapidity, Delta y, relative azimuthal angle, Delta phi, and invariant relative momentum, q(inv). For charged-particle pairs, the width of the balance function in terms of Delta eta scales smoothly with the number of participating nucleons, while HIJING and UrQMD model calculations show no dependence on centrality or system size. For charged-particle and charged-pion pairs, the balance functions widths in terms of Delta eta and Delta y are narrower in central Au + Au collisions than in peripheral collisions. The width for central collisions is consistent with thermal blast-wave models where the balancing charges are highly correlated in coordinate space at breakup. This strong correlation might be explained by either delayed hadronization or limited diffusion during the reaction. Furthermore, the narrowing trend is consistent with the lower kinetic temperatures inherent to more central collisions. In contrast, the width of the balance function for charged-kaon pairs in terms of Delta y shows little centrality dependence, which may signal a different production mechanism for kaons. The widths of the balance functions for charged pions and kaons in terms of q(inv) narrow in central collisions compared to peripheral collisions, which may be driven by the change in the kinetic temperature.

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We report a measurement of high-p(T) inclusive pi(0), eta, and direct photon production in p + p and d + Au collisions at root s(NN) = 200 GeV at midrapidity (0 < eta < 1). Photons from the decay pi(0) -> gamma gamma were detected in the barrel electromagnetic calorimeter of the STAR experiment at the Relativistic Heavy Ion Collider. The eta -> gamma gamma decay was also observed and constituted the first eta measurement by STAR. The first direct photon cross-section measurement by STAR is also presented; the signal was extracted statistically by subtracting the pi(0), eta, and omega(782) decay background from the inclusive photon distribution observed in the calorimeter. The analysis is described in detail, and the results are found to be in good agreement with earlier measurements and with next-to-leading-order perturbative QCD calculations.