相变材料填充结构对地板辐射供暖热性能的影响研究

针对相变蓄能材料用于地板辐射供暖中存在热响应时间长、经济成本高等问题,提出了减少相变材料填充量的半层式填充结构形式,并将其和无填充式、常规相变填充进行对比分析。通过对不同形式地板辐射供暖的模拟分析,得出了不同相变材料填充结构条件下地板表面温度、室内空气温度、地板表面热流密度和平均蓄放热速率等热性能指标。对比结果表明:4种相变材料填充方案中,相变材料位于下半层在2种间歇式运行工况下地板表面温度最高,分别达到了29.2、30.3℃;蓄热升温速率最快,且能够维持室内温度处于热舒适范围内时间分别达到了18.5、21.9 h,具有较好的热性能优势。

相变围护结构热性能评价方法和影响因素研究

为了揭示相变围护结构内、外表面的传热机理,文章针对夏季相变围护结构的两种不同传热过程,提出了"隔热因子"和"吸热因子"两个评价指标用于评价其传热性能,并利用热阻法建立了两种传热情况下的传热方程,对两个评价指标进行了理论求解;最后对影响两个评价指标的各个因素进行了单因素分析,得出不同因素对评价指标影响的规律。该研究可以为相变围护结构的参数选择提供理论依据和技术支持。

相变围护结构的研究及发展

分析了适合建筑围护结构中储能用的相变材料的种类、特点和选择原则,讨论了相变材料与建筑围护结构的结合方式及可行性,综述了相变蓄能围护结构在国内外的研究及发展现状,同时提出了待解决的问题及未来研究的方向。

相变材料与建筑基体复合的相变维护结构热特性探讨

将相变材料与建材基体复合,构筑成一种新型相变蓄能建筑维护结构。这种建筑维护结构可充分利用夜间低价电蓄热,供次日白天的辅助热源,降低采暖系统的投资与能耗,改善室内环境。主要探讨了相变材料与石膏等建筑基体复合后相变建筑维护结构的热特性。

有限温度Z_5 格点规范理论的相变结构(英文)

利用改进的ＭＫ 重正化群方法，讨论了最高温度Ｔ ＝ １／ａ 下的Ｚ５ 格点规范理论的相变结构和温度耦合常数空间中的相变线，并计算了固定点的临界指数，所得结果支持ＳＹ 预言．

被动式相变房间传热性能的数值模拟

将相变材料以适当的方式加入围护结构,可提高围护结构的蓄热能力,降低夏季冷负荷和冬季热负荷,达到建筑节能的目的。以建立普通房间和相变房间的数学模型,利用ANSYS软件数值模拟,研究典型气象年室外气象参数波动情况下房间内壁温度和热流的变化规律。研究结果将为相变围护结构的实际应用提供参考依据。

十二醇/三聚氰胺-甲醛核壳结构材料的制备

采用原位聚合法以三聚氰胺-甲醛树脂为壁材、十二醇为芯材,合成了十二醇/三聚氰胺-甲醛核壳结构材料.研究了复相乳液形成区、反应物摩尔比及反应条件对合成的影响,确定了合适的反应工艺,并利用红外光谱仪、扫描电子显微镜、热失重分析仪及激光粒度分析仪对产物进行红外特征吸收光谱、表面形态、粒径分布以及热质量损失情况的分析。结果表明,该材料具有良好的外观特性及热稳定性,可用于特种涂料的制备。

热弹性马氏体相变连续介质热力学研究

介绍形状记忆合金热弹性马氏体相变连续介质热力学研究方法和最新进展,着重分析了在推广的非线性弹性力学的框架下,应用变分方法研究热弹性马氏体相变的理论和方法、存在的问题及发展趋势.首先介绍如何计算马氏体相变24种变体的变形梯度,然后拓展非线性弹性力学,引入描述相变的多阱非凸弹性势能,进而讨论了界面能和非局部能对相变微结构和相变过程的影响的相关研究理论方法和进展.

相变蓄能墙体在主/被动建筑中的应用现状

本文概括阐述了国内外对相变蓄能墙体的研究现状,对相变材料(PCM)的分类,相变材料的封装形式,相变墙体结构以及学者们针对提高墙体热性能的相变墙体结构优化研究进行了归纳总结,简述了学者们为优化相变材料利用率以及更好地实现建筑节能所做的研究工作,提出了一些可以进一步探讨的方向。为学者们进一步研究优化相变墙体结构,增强墙体热性能,增大建筑节能提供了一些参考方向。

Antiphase boundary-like structure in α′′ martensite of TC21 titanium alloy

The morphology and formation mechanism of the substructure of martensite in TC21 alloy was investigated by XRD and TEM. The results showed that the martensitic transformation from β to α＂ occurs upon quenching after solution treatment between 960-1000 ℃. The antiphase boundary （APB）-like structure was observed clearly in the α＂ martensite plates. The APB-like contrasts exist along the （001） and （020） planes of α＂ martensite. This APB-like structure of α＂ martensite was identified as a kind of stacking fault with an APB-like morphology induced by martensitic transformation and not by order/disorder transition. During martensitic transformation, martensitic domains nucleate and grow, eventually encounter each other, resulting in the formation of the APBdike contrast.

夏热冬冷地区变墙体适用性模拟分析

外保温围护结构是我国目前实现"建筑节能规范"要求的主要措施,而相变围护结构因其蓄热量大、温度波动小等优点近年来得到广泛的研究。尤其需要针对性的研究在具体地区和气候条件下节能效果最好、最舒适的围护结构。针对夏热冬冷地区,通过对比围护结构相变材料层和保温层对围护结构能耗及内表面温度的影响,分析相变围护结构在夏热冬冷地区—湖南长沙的适用性。模拟结果表明:在长沙夏季典型气象条件下,更适合使用外保温围护结构。

相变-保温复合结构的温度-时间响应研究

以自制定形相变材料(PCM)构件,与EPS板组成相变-保温复合结构,在升温-降温过程中,测试了该结构的温度-时间响应。结果表明:加入PCM构件与多层EPS板形成相变-保温复合结构后,系统热惰性显著提高。其中PCM在第2层或第3层位置时,较之标准实验结果,升温用时和降温用时分别延长了12倍和6倍,而在第4层时相变过程不够充分。从最内层的温度-时间响应看,PCM在第3层时蓄热保温效果最好,并以简化的等效热流图对此进行了分析。若将此定型相变材料制成板片状结构嵌入外墙保温材料内适当位置蓄热保温,可增强墙体热惰性,达到建筑节能目的。

Bi-modal microstructure in a powder metallurgical ferritic steel

Ferritic steel with a nominal composition of Fe-14Cr-3W-0.42Ti-0.32Y was prepared by mixing gas-atomized prealloyed powder and mechanically alloyed powder. The microstructure is much different fxom other ferritic steels with the same composition and prepared via only mechanically alloyed powder. A bi-modal structure, which consists of pure ferritic grains and martensitic grains, was obtained after hot forging and air cooling. A phase transformation of αbcc→γfcc→α＇bcc was also discovered in microstructural observation. The bi-modal microstructure shows a good combination of high strength and high ductility.

Analysis of Genetic Variation and Population Structure of Starch Synthesis-related Genes in Indica Rice Cultivars

In this study, 34 molecular markers of starch synthesis-related genes were used to evaluate the genetic variation and population structure of 87 indica rice cultivars from different countries and regions. The results showed that a total of 80 alleles were amplified using 34 primer pairs, with an average of 2.5 alleles per locus. The allele number varied from 2 to 6 among various cultivars. Shannon＇s diversity index of molecular markers varied from 0.303 to 0.796, with an average of 0.539. Polymorphism information content （PIC） varied from 0.084 to 0.658, with an average of 0.295. The genetic similarity coefficients of 87 indica rice cultivars ranged from 0.265 to 0.990, indicating significant genetic differences of starch synthesis-related genes among different cultivars, but the variation frequency of alleles varied among different cultivars. Population structure analysis showed that these 87 indica rice cultivars were divided into three categories. Genetic differences were small within the same category but great among different categories. Moreover, indica rice cultivars with simple genetic components accounted for 39.1% and those with complex genetic background accounted for 60.9%. This study may not only provide theoretical basis for genetic improvement of rice starch quality, but also lay a solid foundation for subsequent association analysis of rice quality-related traits.

液晶非线性光学

本文综述了液晶非线性光学的一般原理,描述了液晶中的各种电动流体力学的不稳定性,报道了我们所得到的各种新的实验结果和可能的应用,指出了液晶非线性光学现代研究倾向.

Effects of Co and Al addition on martensitic transformation and microstructure in ZrCu-based shape memory alloys

The effect of ternary alloying element Al and quaternary alloying element Co on the martensitic transformation of ZrCu-based shape memory alloy was investigated. The results show that the addition of Al and Co in ZrCu alloy decreases both the martensitic transformation temperature and the martensitic transformation temperature hysteresis. Transmission electron microscope (TEM) observations reveal that theCm martensite structure is the preferential formation phase. The intervariant structures in ZrCuAlCo alloy are (021) type I twins, while the dominant substructures inside the martensite variant are the (001) compound twins. With the increase of Co content, tensile fracture strength and strain are improved obviously.

Structural Transition and Magnetic Property of Bi1-xYbxFeO3

Bi1-xYbxFeO3（0〈x〈0.2） powders have been synthesized using a sol-gel method. The X- ray diffraction data show a structural transition from the rhombohedral R3c phase to the orthorhombic Pnma phase between x=0.1 and 0.125, which should induce a ferroelectric- paraelectric transformation. The phase transition is also proven by the Raman spectroscopy. A moderate signal on magnetization appears to illustrate the enhancement of magnetization at the transformation boundary, which is suggested to be the destruction of the spin cycloid structure at low concentration. The appearance of antiferromagnetic ordering is proposed to account for the afterward reduction of the magnetization at high concentration.

Mechanism of microwave assisted suspension magnetization roasting of oolitic hematite ore

Oolitic hematite is an iron ore resource with rich reserves,complex composition,low grade,fine disseminated particle sizes,and a unique oolitic structure.In this study,a microwave-assisted suspension magnetization roasting technology was proposed to recover and utilize the ore.The results showed that under the conditions of microwave pretreatment temperature of 1050℃ for 2 min,a magnetic concentrate with an iron grade of 58.72%at a recovery of 89.32%was obtained by microwave suspension magnetization roasting and magnetic separation.Moreover,compared with the no microwave pretreatment case,the iron grade and recovery increased by 3.17%and 1.58%,respectively.Microwave pretreatment increased the saturation magnetization of the roasted products from 24.974 to 39.236(A∙m^(2))/kg and the saturation susceptibility from 0.179×10^(−3) m^(3)/kg to 0.283×10^(−3) m^(3)/kg.Microcracks were formed between the iron and gangue minerals,and they gradually extended to the core of oolite with the increase in the pretreatment time.The reducing gas diffused from outside to inside along the microcracks,which promoted the selective transformation of the weak magnetic hematite into the strong magnetic magnetite.

Phase composition, transition and structure stability of functionally graded cemented carbide with dual phase structure

The phase composition, phase transition and phase structure transformation of the wire-cut section of functionally graded WC-Co cemented carbide with dual phase structure were investigated by XRD phase analysis. It is shown that the composition of η phase in the core zone is Co_3W_3C (M_6 C type). The structure of cobalt based solid solution binder phase is fcc type. At the cooling stage of the sintering process, the phase transition of η phase, i.e. M_6C→M_12C and the martensitic phase transition of the cobalt based solid solution binder phase, i.e. fcc→hcp are suppressed, which facilitates the strengthening of the alloy. Because the instantaneous temperature of the discharge channel is as high as 10 000 ℃ during the wire cutting process, the processed surface is oxidized. Nevertheless, the oxide layer thickness is in micro grade. In the oxide film, η phase is decomposed into W_2C and CoO, and cobalt based solid solution binder is selectively oxidized, while WC remains stable due to the existence of carbon containing liquid organic cutting medium.

First principles study of structural, electronic and mechanical properties of transition metal hydrides(TMH, TM=Mo,Tc, Ru)

The structural, electronic and mechanical properties of transition metal hydrides （TMH, TM=Mo, Tc, Ru） are investigated by means of first principles calculation based on density fimctional theory with generalized gradient approximation. Among the five crystallographic structures that have been investigated, the cubic phase is found to be more stable than the hexagonal ones. A structural phase transition from ZB to WC in Moll, NaC1 to NiAs in TcH and NaCI to ZB to NiAs in RuH is also predicted under high pressure. The calculated elastic constants indicate that all the three hydrides are mechanically stable at ambient pressure.