共查询到20条相似文献，搜索用时 31 毫秒
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Arthur K. Doolittle 《Journal of The Franklin Institute》1973,295(3):217-237
A volume—entropy—energy (VSE) equation of state, unlike a PVT equation of state, can be used to calculate “all conceivable” thermodynamic quantities, including specific heats, without supplemental calorimetric data. A VSE equation for liquids, based on simple theoretical concepts, is proposed and, in this paper, applied specifically to n-heptane. This equation of state requires only ten arbitrary parameters, seven of which may be calculated from data at but three temperatures, e.g., 25°, 50° and the normal boiling point. It yields calculated values of many thermodynamic properties nearly as accurate as the best experimental data, from a few degrees above the melting temperature all the way to the critical temperature. PVT equations of state of comparable accuracy over such broad ranges would require at least as many parameters, as well as supplemental calorimetric data, to calculate many thermodynamic quantities that are obtainable directly from our VSE equation. 相似文献
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复杂晶体的化学键和非线性光学效应 总被引：1，自引：0，他引：1
系统地提出了复杂晶体化学键的介电理论方法 ,计算了一些非线性晶体的二阶极化系数dij.计算结果和实验值符合很好 ,同时表明这种方法不仅可应用于复杂晶体 ,还提供了材料设计的某些依据 . 相似文献
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对流换热边界条件下球体内固液相变过程移动热源法求解 总被引：1，自引：0，他引：1
应用移动热源法求解了对流换热条件下球体内具有明显相变界面的固液相变问题,分析了球体半径、相变材料潜热、外界对流换热条件对相变过程的影响,并进一步考虑实际相变过程存在的变对流边界条件,构造了一实用解法.为求解相变问题的数值方法提供了一校核其可靠性的新途径,还为实验结果提供了相互比较的数据.该方法及其结果对相变材料的分析与设计具有重要的实用价值 相似文献
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研究地质流体的物理化学性质和地球化学行为是地球系统科学研究所面对的挑战性课题之一。与诸如实验和物理化学建模等传统研究方法相比，分子水平上的计算机模拟在解决极端条件下流体体系物理化学性质方面表现出明显的优势，成为定量研究地球内部不同层圈中地质流体特点及其作用规律的有效途径。本论文简要介绍了我们把计算机模拟技术应用到地质流体研究中的成果，主要可概括为：（1）利用蒙特卡罗计算机模拟方法，我们成功地模拟了地质流体体系相平衡和相变，取得了与实验一致的结果，从而在计算机上实现了相平衡研究，与花费昂贵的实验相比具有方法学上的先进性；（2）通过分子动力学模拟研究水的物理化学性质，我们把水的PVT数据从实验所允许的温压范围（温度小于1873.15 K、压力低于5万大气压）扩展到2000 K、20万大气压，并提出了一个适用于宽广温压条件下的状态方程；（3）通过分子动力学和蒙特卡罗模拟，我们建立了一个CO2分子模型，它能同时准确预测CO2的各种物理化学性质和行为（PVT性质、相平衡、潜热、结构性质和动力学性质）；（4）通过分子动力学模拟研究氯化锂在溶液中的离子水化和缔合性质，我们得到了与实验和量子力学模拟一致的结果，与此同时还揭示了离子水化和缔合过程的微观机制。 相似文献
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利用模匹配法来分析正V形槽波导的主模特性,首先求出波导横截面上各子区域中的电磁场分量,然后在边界上进行切向场量的匹配,得到关于求解主模截止波数的特征方程。用本文方法对正V形槽波导波导波长的计算结果与文献中的实验值吻合很好。与现有的理论值相比较,本文结果最精确。 相似文献
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Dale B. Cherchas 《Journal of The Franklin Institute》1981,312(1):31-40
The probability of wheel climb commencing is calculated using Nadal's formula as a basis. In particular, the functional form of Nadal's formula is maintained with normal probability density functions used to describe the two arguments in Nadal's formula, namely contact plane angle and coefficient of friction at the contact point. The theoretical value of the probability of wheel climb commencing for a given lateral/vertical force ratio value at the wheel flange–railhead interface is then compared with experimental results for positive angles of attack. Theoretical results for negative angles of attack are generated for several cases. 相似文献
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利用1979-2011年秋季9-10月陕西96个台站的逐日降水资料和NCEP/NCAR再分析月平均资料,分析了孟加拉湾潜热通量与陕西秋季降水的关系,指出了影响陕西秋季旱涝的热源关键区域,并就其影响陕西秋季旱涝的成因机制进行初步分析,得出以下结论:陕西秋季降水与孟加拉湾主体海域的潜热通量变化为显著负相关,当该海域潜热通量偏弱时,乌拉尔山高压偏强,西太平洋副热带高压位置偏西偏北,孟加拉湾至青藏高原南侧多低槽活动,形成了有利于陕西秋季降水的环流形势,同时,陕西地区的偏南水汽输送增强,大气辐合上升运动也增强,陕西秋季降水偏多的可能性较大。此外,孟加拉湾上一年冬季、当年夏季的潜热通量大小与秋季的有显著正相关关系,因此,该海域上一年冬季、当年夏季的潜热通量强弱可以作为预测陕西秋季降水多寡的重要参考。 相似文献
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轴对称双倒易边界元法的f函数及其奇性处理 总被引：2，自引：0，他引：2
基于右端项为径基函数的三维泊松方程,推导了轴对称情况下双倒易边界元方程求和形式的 f函数通式.通过对f函数取积分平均和根据计算区域特点选取不同类型的 f函数组合,消除了f函数在对称轴上呈现奇性的不足.通过计算轴对称实心圆柱体和球体的非稳态导热问题,很好地验证了对f函数的选择和处理的可行性. 相似文献
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A general theory is developed for extended bandwidth operation of actively compensated finite gain amplifiers. Designs for three new circuits are given which implement the theory. These circuits employ only operational amplifiers and resistors and their gains depend only on their resistor ratios. Thus they are suitable for IC fabrication. Further in IC technology, the characteristics of the operational amplifiers as well as the resistor ratios track closely with each other with reference to temperature and aging. Thus the extended bandwidth operation of the amplifiers will be available over a wide temperature range as well as under varying aging conditions. Their characteristics can be tuned easily by trimming only two resistors. Applications of the new amplifiers have been considered in RC active filters as well as in inductance simulation schemes. Experimental results are given which closely agree with theoretical predictions. The results also indicate that substantial improvement in the usable bandwidth of the circuits employing the new amplifiers may be expected over those using the conventional design of finite gain amplifiers. 相似文献
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In this paper, for solving future equation systems, two novel discrete-time advanced zeroing neural network models are proposed, analyzed and investigated. First of all, by using integral-type error function and twice zeroing neural network (or termed, Zhang neural network) formula, as the preliminaries and bases of future problems solving, two continuous-time advanced zeroing neural network models are presented for solving continuous time-variant equation systems. Secondly, a one-step-ahead numerical differentiation rule termed 5-instant discretization formula is presented for the first-order derivative approximation with higher computational precision. By exploiting the presented 5-instant discretization formula to discretize the continuous-time advanced zeroing neural network models, two novel discrete-time advanced zeroing neural network models are proposed. Theoretical analyses on the convergence and precision of the discrete-time advanced zeroing neural network models are proposed. In addition, in the presence of disturbance, the proposed discrete-time advanced zeroing neural network models still possess excellent performance. Comparative numerical experimental results further substantiate the efficacy and superiority of the proposed discrete-time advanced zeroing neural network models for solving the future equation systems. 相似文献
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以波传播的观点 ,将流动工况视为连续波与动力波相互作用在特定流动条件下的非线性解 ,尝试提出了两相流分析的一种新思路 .从一维气液两相流守恒方程出发 ,应用气液两相流漂移流模型 ,推导了空泡率双曲型守恒方程 ,用特征线法数值求解气液两相流空泡率分布的传播过程 ,对传播稳定性和流型转变进行讨论 .数值分析表明 ,低空泡率时发生流型转变的位置相对于两相流平均速度将向下游蔓延 ;而高空泡率时则相对地向上游蔓延 ;空泡率很高时空泡率分布传播过程中将不会出现流型转变 .计算表明 :流型转变起始点的空泡率为 0 2 7,空泡率达到 0 5 8时流型转变终止 ;这与文献报告的气液两相流实验结果符合较好 相似文献
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J.A.C. Yule 《Journal of The Franklin Institute》1943,236(5):473-487
The theoretical and experimental quantitative relationships between the dot diameter, dot area, and density of a halftone are given. Experimental results do not agree exactly with the theoretical relationships except for screen negatives and positives with sharp dots.For accurate rendering, highlight dots in a reproduction must increase extremely rapidly in size for small density increments in the highlights of an original. A “emi-dark-field” densitometer is described which eliminates the effect of dot fringe in measuring densities of screen positives. The relationship between density of screen positive and density of proof is briefly discussed. 相似文献
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本文对连续分布的置信限曲线变化规律进行了研究。证明了分布函数的百分率Ｐｔ置信度为γ的单侧置信上（下）限曲线，同时也是具有该分布函数的母体百分位值的置信度为γ的单侧置信下（上）限曲线，并且提出了一种利用秩分布确定置信限曲线数学表达式中参数的方法，由此可求出可靠度的置信限。 相似文献
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Parry Moon 《Journal of The Franklin Institute》1940,230(5):583-617
A wealth of data on sunlight has been obtained by astrophysicists, meteorologists, and others; but this information has been scattered through the literature and has not been generally available to engineers.The present paper correlates some of the data and specifies a proposed standard spectral-distribution curve for sunlight outside the atmosphere. Methods are given also for the calculation of the spectral irradiation curve for any elevation above sea level and for any air mass, and these methods lead to proposed standard curves to be used in engineering calculations dealing with direct sunlight at sea level.These curves are checked against independent data on total irradiation, ultraviolet irradiation, illumination, and color temperature. In all cases, the agreement between calculated and experimental results gives confidence in the validity of the proposed curves for various engineering applications. 相似文献
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参照腾冲－梁河地热系统的特点及岩浆活动的一般特征,应用二维有限单元法定量模拟了热泉地区岩浆侵入的热演化过程．计算中,采用等效比热方法处理潜热释放问题,同时建立了大气降水对热液循环的补给模型．计算结果表明：半宽度为０．０５～１ｋｍ的侵入体产生的热扰动对热泉地区的影响大致在４ｋｍ的距离范围内 相似文献
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樊阳程 《科学技术与辩证法》2011,(6):32-36
西蒙对归纳问题的思考始于科学发现逻辑的探讨。最初,他试图将归纳法排除在科学发现逻辑之外,但未获成功。在以机器发现方法研究科学发现逻辑的过程中,西蒙在归纳问题上发生了表征转变,将归纳法合理性的辩护从逻辑角度转到认知视角上来。基于批判现代经验论的温和自然主义立场,西蒙从归纳的似然性和人类认知理性的有限性两个方面抛弃了归纳合理性逻辑辩护的认识论传统,提供了归纳问题的认知解答。 相似文献