4,727 research outputs found

    Gear optimization

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    The use of formal numerical optimization methods for the design of gears is investigated. To achieve this, computer codes were developed for the analysis of spur gears and spiral bevel gears. These codes calculate the life, dynamic load, bending strength, surface durability, gear weight and size, and various geometric parameters. It is necessary to calculate all such important responses because they all represent competing requirements in the design process. The codes developed here were written in subroutine form and coupled to the COPES/ADS general purpose optimization program. This code allows the user to define the optimization problem at the time of program execution. Typical design variables include face width, number of teeth and diametral pitch. The user is free to choose any calculated response as the design objective to minimize or maximize and may impose lower and upper bounds on any calculated responses. Typical examples include life maximization with limits on dynamic load, stress, weight, etc. or minimization of weight subject to limits on life, dynamic load, etc. The research codes were written in modular form for easy expansion and so that they could be combined to create a multiple reduction optimization capability in future

    RLSynC: Offline-Online Reinforcement Learning for Synthon Completion

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    Retrosynthesis is the process of determining the set of reactant molecules that can react to form a desired product. Semi-template-based retrosynthesis methods, which imitate the reverse logic of synthesis reactions, first predict the reaction centers in the products, and then complete the resulting synthons back into reactants. These methods enable necessary interpretability and high practical utility to inform synthesis planning. We develop a new offline-online reinforcement learning method RLSynC for synthon completion in semi-template-based methods. RLSynC assigns one agent to each synthon, all of which complete the synthons by conducting actions step by step in a synchronized fashion. RLSynC learns the policy from both offline training episodes and online interactions which allow RLSynC to explore new reaction spaces. RLSynC uses a forward synthesis model to evaluate the likelihood of the predicted reactants in synthesizing a product, and thus guides the action search. We compare RLSynC with the state-of-the-art retrosynthesis methods. Our experimental results demonstrate that RLSynC can outperform these methods with improvement as high as 14.9% on synthon completion, and 14.0% on retrosynthesis, highlighting its potential in synthesis planning.Comment: 11 pages, 8 figures, 6 table

    Pair Distribution Function of One-dimensional "Hard Sphere" Fermi and Bose Systems

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    The pair distributions of one-dimensional "hard sphere" fermion and boson systems are exactly evaluated by introducing gap variables.Comment: 4 page

    Few-Body Systems Composed of Heavy Quarks

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    Within the past ten years many new hadrons states were observed experimentally, some of which do not fit into the conventional quark model. I will talk about the few-body systems composed of heavy quarks, including the charmonium-like states and some loosely bound states.Comment: Plenary talk at the 20th International IUPAP Conference on Few-Body Problems in Physics, to appear in Few Body Systems (2013

    Possible superconductivity above 25 K in single crystalline Co-doped BaFe2_{2}As2_{2}

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    We present superconducting properties of single crystalline Ba(Fe0.9_{0.9}Co0.1_{0.1})2_{2}As2_{2} by measuring magnetization, resistivity, upper critical field, Hall coefficient, and magneto-optical images. The magnetization measurements reveal fish-tail hysteresis loop at high temperatures and relatively high critical current density above Jc=105J_{c}=10^{5} A/cm2^{2} at low temperatures. Upper critical field determined by resistive transition is anisotropic with anisotropic parameter \sim 3.5. Hall effect measurements indicate that Ba(Fe0.9_{0.9}Co0.1_{0.1})2_{2}As2_{2} is a multiband system and the mobility of electron is dominant. The magneto-optical imaging reveals prominent Bean-like penetration of vortices although there is a slight inhomogeneity in a sample. Moreover, we find a distinct superconductivity above 25 K, which leads us to speculate that higher transition temperature can be realized by fine tuning Co-doping level.Comment: 4 pages, 5 figure

    Momentum Distribution for Bosons with Positive Scattering Length in a Trap

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    The coordinate-momentum double distribution function ρ(r,p)d3rd3p\rho ({\bf r}, {\bf p}) d^{3}rd^{3}p is calculated in the local density approximation for bosons with positive scattering length aa in a trap. The calculation is valid to the first order of aa. To clarify the meaning of the result, it is compared for a special case with the double distribution function ρwd3rd3p\rho_{w}d^{3} rd^{3}p of Wigner.Comment: Latex fil

    Experimental Violation of Bell Inequality beyond Cirel'son's Bound

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    The correlations between two qubits belonging to a three-qubit system can violate the Clauser-Horne-Shimony-Holt-Bell inequality beyond Cirel'son's bound [A. Cabello, Phys. Rev. Lett. 88, 060403 (2002)]. We experimentally demonstrate such a violation by 7 standard deviations by using a three-photon polarization-entangled Greenberger-Horne-Zeilinger state produced by Type-II spontaneous parametric down-conversion. In addition, using part of our results, we obtain a violation of the Mermin inequality by 39 standard deviations.Comment: 4 pages, 3 figure

    Upregulation of Phosphodiesterase type 5 in the Hyperplastic Prostate

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    Both erectile dysfunction (ED) and lower urinary tract symptoms (LUTS)/benign prostatic hyperplasia (BPH) are common in the aging male. Numerous clinical trials have demonstrated the efficacy and safety of phosphodiesterase type 5 inhibitors (PDE5-Is) for treating LUTS/BPH with/without ED. However, the influence of BPH on prostatic PDE5 expression has never been studied. A testosterone-induced rat model of BPH was developed and human hyperplastic prostate specimens were harvested during cystoprostatectomy. PDE5, nNOS, eNOS and α1-adrenoreceptor subtypes (α1aARs, α1bARs and α1dARs) were determined with real-time RT-PCR for rat tissues whilst PDE5 and α1-adrenoreceptor subtypes were determined in human samples. PDE5 was further analyzed with Western-blot and histological examination. Serum testosterone was measured with ELISA. The rat BPH model was validated as having a significantly enlarged prostate. PDE5 localized mainly in fibromuscular stroma in prostate. Our data showed a significant and previously undocumented upregulation of PDE5 in both rat and human BPH, along with increased expression of nNOS and α1d ARs for rat tissues and α1a ARs for human BPH. The upregulation of PDE5 in the hyperplastic prostate could explain the mechanism and contribute to the high effectiveness of PDE5-Is for treating LUTS/BPH. Fibromuscular stroma could be the main target for PDE5-Is within prostate
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