砼强度准则在井壁结构中的应用研究

本文根据井壁结构模型试验结果,对目前具有代表性的复杂应力状态下的砼强度准则进行了分析和对比,找到了一种比较适合于井壁结构的砼强度准则,从而为井壁结构承载能力的合理计算提供了理论基础.     

高效效益推进山西农业综合开发的对策与措施

论述了面对农业发展的新形势，进一步推进农业综合开发、提高农业综合效益所具有的重要现实意义，介绍了山西省农业综合开发的已有成就，并指出了高效益开展农业综合开发应遵循的对策和措施。     

锻炼对老年人肺通气功能影响的研究

本文采用电子肺活量计对218名老人进行了肺通气功能的测试。测试结果表明:体育锻炼对老年人肺通气功能有良好影响。本文为老年人肺通气功能的研究、评价及老年人体育运动的研究提供了实验性依据。     

Thermodynamic properties of organic compounds in aqueous solution. II. Apparent molal heat capacities of piperidines,morpholines, and piperazines

Apparent molal heat capacities of some piperidine, morpholine, and piperazine derivatives in aqueous solution have been determined by adiabatic calorimetry in the temperature range 20–55°C and in the molality range 0.2–1m. Comparison of experimental values with those calculated through group contributions, found for monofunctional compounds, indicates strong interactions between the hydrophilic centers. An interpretation is given of the possible mechanism of this interaction. Also, values of ΔC _p for the addition reaction of proton to nitrogen centers of mono- and bifunctional organic compounds are examined.     

The thermodynamics of proton dissociation of adenine

The thermodynamic quantities associated with ionization of the N₁ and N₉ protons of adenine have been calorimetrically determined as a function of temperature. The H values for proton dissociation of these groups, with pK values of 4.19 and 9.92, were found to be 5.1 and 9.1 kcal/mole, respectively, at 25°C, =0.025. The C _p values for proton dissociation of these groups were estimated to be –11 and –17 cal/mole-deg. These results indicate that the large heat capacity changes observed during conformational transitions of polynucleotides are not the result of ionization of the bases.     

Non isothermal heat capacities and chemical reactions using a modulated DSC

An evaluation of measurements of heat capacities by modulated differential scanning calorimetry, MDSC is presented. Heat capacities were obtained from 130 to 550 K by a non isothermal technique in which a periodic modulation was added to the linear heating rate. Effects of amplitude and period of modulation, sample weight, sample type, pan type, and cell imbalance are described. Results are compared with those obtained using the isothermal technique. Heat capacity could be measured well into the decomposition region and separated from the non reversing signal due to chemical reaction (degradation), thus allowing a precise detection of onsets of the thermal degradation. This additional information will aid in the interpretation of the degradation chemistry, a field vital for the petroleum-industry.Dedicated to Professor Bernhard Wunderlich on the occasion of his 65th birthdayPart of this paper was presented at the 23rd Conference of the North American Thermal Analysis Society, Toronto, Canada, September 25–28, 1994.The author (MVN) acknowledges the experimental assistance provided by J. Balogh of Exxon Research and Engineering Company, Linden. Helpful discussions with A. Boller of the University of Tennessee at Knoxville, Dr. Y. Jin, General Electrical, and Dr. S. Sauerbrunn formerly of TA Instruments are also acknowledged.     

基于卡诺机的大规模MIMO通信容量建模及性能分析

信息本质上以能量和熵的形式在通信系统中流动,类似于传统热机中的能量流动过程。结合热力学卡诺机模型和经典香农信息论理论,建立了一个广义的热力学(multiple input multiple output, MIMO)通信系统模型,对大规模天线通信场景下使用前向纠错码的信道容量进行分析。利用通信系统中存在的自由度和熵的概念,推导了热力学模型下的广义信道容量,并对信道容量与噪声自由度及编码开销的关系进行验证仿真。仿真结果表明,所提出的热力学信道容量与香农信道容量是一致的。     

对“铁路运输走向市场”若干问题的认识

“铁路运输走向市场”的第一层含义是铁路运输企业经营市场化,第二层含义是铁路运输作为市场经济的基础条件,必须起到保证整个社会主义市场经济运行的基础作用,在我国当前条件下,必须把提高运输能力作为铁路运输走向市场的出发点和归宿。在提高运输能力过程中,必须科学处理运输能力与运输效率的关系．以市场经济和社会基础性的眼光看,我国铁路运输高效率并不一定是一件好事。铁路运输走向市场可以采取“重点突破,整体推进”的战略。     

路段通行能力的动态微观仿真研究

用动态微观仿真方法研究路段通行能力,从微观的角度出发,考虑驾驶员,车辆,道路, 环境和交通规划的相互关系对通行能力的影响并建立了仿真模型。     

间歇式压滤机的优化研究

在计入洗涤时间这一重要因素的前提下,以间歇式压滤机的生产能力最大为优化目标函数,得出其最佳操作时间,经实例验证,优化效益显著．