200MW非再热双抽供热机组变工况计算及工况图的绘制

工况图在热电厂的设计和运行中具有广泛的用途。本文根据引进型双抽非再热200MW供热机组的技术特点，通过编程在纯凝汽工况、单抽工业抽汽工况、单抽采暖抽汽工况和双抽供热等典型变工况计算的基础上，完成了当新蒸汽负荷、工业抽汽负荷和采暖抽汽负荷发生改变时的变工况计算，并绘制了该机组的运行工况图．     

A new 3s–3d heterometallic polymer containing N‐methyliminodiacetic acid: synthesis,structure and characterization

A new complex {[Na₂(H₂O)₃(µ‐L)₂Cu]₄}_∞ (L = N‐methyliminodiacetic acid) has been synthesized and structurally characterized. The complex crystallizes in the monoclinic, space group C2/c, with the unit cell parameters a = 16.556(3) Å, b = 8.0622(13) Å, c = 12.671(2) Å, α = 90°, β = 95.849(2)°, γ = 90°. The central metal Cu (II) ion is coordinated with two nitrogen atoms and four oxygen atoms belonging to two ligands. Simultaneously, the sodium is six‐coordinated with oxygen atoms coming from the ligand and water molecule; the sodium atoms related are bridged by oxygen atoms, forming a sodium chain. The structure consists of CuL₂ moieties linked by sodium chain via the exo oxygen atoms of two ligands, forming a novel three‐dimensional structure. Moreover, elemental analysis, IR, UV‐vis, ESR spectroscopy and thermal stability were determined. Copyright © 2007 John Wiley & Sons, Ltd.     

Thermal and X‐ray analysis of polymorphic crystals,melting, and crystalline transformation in poly(butylene adipate)

Polymorphic crystals and complex multiple melting behavior in an aliphatic biodegradable polyester, poly(butylene adipate) (PBA), were thoroughly examined by wide‐angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC). Further clarification on mechanisms of multiple melting peaks related to polymorphic crystal forms in PBA was attempted. More stable α‐form crystal is normally favored for crystallization from melt at higher temperatures (31–35 °C), or upon slow cooling from the melt; while the β‐form is the favored species for crystallization at low temperatures (25–28 °C). We further proved that PBA crystallization could also result in all α‐form even at low temperatures (25–28 °C) if it crystallized with the presence of prior α‐form nuclei. PBA packed with both crystal forms could display as many as four melting peaks (P1 ? P4, in ascending temperature order). However, PBA initially containing only the α‐crystal exhibited dual melting peaks of P1 and P3, which are attributed to dual lamellar distributions of the α‐crystal. By contrast, PBA initially containing only the β‐crystal could also exhibit dual melting peaks (P2 and P4) upon scanning. While P2 is clearly associated with melting of the initial β‐crystal, the fourth melting peak (P4), appearing rather broad, was determined to be associated with superimposed thermal events of crystal transformation from β‐ to α‐crystal and final re‐melting of the new re‐organized α‐crystal. Crystal transformation from one to the other or vice versa, lamellae thickening, annealing at molten state, and influence on crystal polymorphism in PBA were analyzed. Relationships and mechanisms of dual peaks for isolate α‐ or β‐crystals in PBA are discussed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1662–1672, 2005     

Fluorinated comblike homopolymers: The effect of spacer lengths on surface properties

A series of polyacrylate monomers with F‐alkylalkyl [F(CF₂)_n(CH₂)_n′] side groups were prepared by free‐radical polymerization. The effect of the chemical structure on the surface properties of poly(ethylene terephthalate)s was evaluated by variations in the relative length of the fluorocarbon and hydrocarbon units in the side group. The resulting polymers were quite surface‐active in the solid state. The surface and bulk organization was investigated by X‐ray photoelectron spectroscopy analysis. A strong correlation between the bulk organization and surface properties of the polymers was established. The outmost layer, formed from trifluoromethyl groups and some ester functions, suggests that the side chain is arranged irregularly in the polymer–air interface. The length of the lateral chain governs this organization: long fluorinated chains and short hydrocarbon spacers are essential elements of the molecular design for such low‐surface‐energy materials. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3737–3747, 2005     

The kinetic behaviour and thermal stability of commercially available explosives

Summary Manufactures of commercially available explosives guarantee a certain lifetime of their products. In the commercial field this lifetime is usually large enough. The explosive is normally used long before the end of its lifetime. It may happen that these explosives are stored for a long time in a bunker where they sometimes exceed their lifetime. A large set of commercial explosives is characterized with a TG by heating small samples in aluminium sample cups from room temperature to 550°C, under a nitrogen atmosphere, with three different heating rates (2, 5 and 10 K min^-1). The activation energy of the decomposition step is determined in several different ways. After this characterization, a selection of the samples (based on economical value) is artificially aged for periods of 2, 4 and 6 weeks. After these ageing profiles the samples are re-investigated with the TG under the same conditions (heating rates and atmosphere) followed by the calculation of the kinetic parameters of the artificially aged materials. According to the TG measurements almost all tested explosives appear to have a much longer lifetime than the values given by the manufacturer. From kinetic point of view, the different methods for calculating the activation energy result in approximately the same parameters. It may conclude that TG seems to be a reliable and quick method for the determination of the lifetime of commercial explosives.     

On some measurements of the propagation properties of thermal waves in the Nb-H and Ta-H systems

Summary By means of an experimental technique based on a nonsteady-state method,i.e. on the propagation of thermal waves, we have measured at room temperature for oscillation frequencies between 6 and 30 mHz the thermal diffusivity, the lateral thermal-loss coefficient and the ?fractional heat loss? in Nb and Ta wires as a function of hydrogen doping. The appearance of hydride formation and precipitation notably changes the behaviour of these quantities. From these measurements it was also possible to calculate the propagation velocity and attenuation coefficient of thermal waves. It was found that the increase of the hydrogen concentration in the solid solution produces a gradual decrease in the velocity and increase in the attenuation coefficient until the solubility limit is reached. For larger hydrogen concentrations, the velocity showed a tendency to increase towards the value of the pure metal, while the attenuation coefficient decreased below the value of the pure metal. These results as a whole appear quite promising for studying the properties of hydrogenated systems. This work was supported by the Gruppo Nazionale di Struttura della Materia of the Consiglio Nazionale delle Ricerche and by the Centro Interuniversitario di Struttura della Materia of the M.P.I., Roma (Italia).     

肿瘤微波热疗的温度场预示及热损伤研究

本文将热损伤的产生和影响引入到肿瘤的微波热疗中。运用微波能量比吸收率SAR的分布分析了微波在组织中的传输和吸收过程,并对微波热疗过程中的温度场、热损伤分布以及血液灌注率的变化进行了数值模拟。     

Multicriteria Optimal Design of a Rectangular Composite Plate Subjected to Biaxial and Thermal Loading

Multicriteria optimization of the structure and geometry of a laminated anisotropic composite plate subjected to the thermal and biaxial action is considered. From known properties of the monolayer and the given values of variable structural parameters, the thermoelastic properties of the layered composite are determined. The criteria to be optimized—the transverse critical load and the longitudinal thermal stresses—depend on two variable design parameters of composite properties and temperature. In the space of the optimization criteria, the domain of allowable solutions and the Pareto-optimal subdomain are found. __________ Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 5, pp. 683–690, September–October, 2005.     

Formation of niobium oxynitrides by rapid thermal processing (RTP)

The potential of rapid thermal processing (RTP) for the preparation of thin films of niobium oxynitrides was investigated. The 200 and 500 nm niobium films were deposited via sputtering on oxidized silicon(1 0 0)- and on sapphire(1 −1 0 2)-substrates. At first, oxidation of niobium films in molecular oxygen and then nitridation in ammonia using an RTP-system was performed. The films were characterized before and after the oxidation and nitridation processes by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and secondary ion mass spectrometry (SIMS). The influence of the two different substrates, amorphous SiO₂ and single crystalline sapphire on the reactivity of the niobium films was studied in dependence of temperature, time of reaction and film thickness. The existence of niobium oxynitride formation was verified for some of the films. In some of the experiments, crack formation in the films or even delamination of the Nb-films from the substrates was observed.     

激光诱导间质肿瘤热疗的数值模拟和实验研究

本文在考虑生物组织物性动态变化的情况下建立了激光诱导间质肿瘤热疗(LITT)的物理数学模型,采用MonteCarlo方法数值模拟了LITT中激光能量在生物组织内的传输过程,基于Pennes生物传热方程和Arrhenius方程数值求解了组织内的温度分布和热损伤体积的变化,分析了热物性及血液灌注率的动态变化对LITT过程的影响,并与相应的离体实验结果进行了对比。数值模拟结果表明,组织的热物性及血液灌注率的动态变化对于热损伤体积的变化具有重要的影响。因此在激光诱导间质肿瘤热疗的数值模拟中应该考虑热物性及血液灌注率的动态变化以期为临床治疗方案的制定提供更为准确的依据。