水合物加热开采时土体变形数值分析

天然气水合物是未来的一种新型能源,但水合物的分解可能使地表产生较大的变形,从而影响到开采平台及地面建筑的稳定性,甚至带来环境灾害.基此,文章利用有限元法对水合物的加热开采过程进行了热力耦合分析,得到了水合物开采过程中土体的变形规律.计算结果表明:水合物加热开采时,土体变形量随着分解半径的增大而非线性增加;当水合物分解半径为40m时,地表最大沉降迭0.38m,最大水平位移为0.12m.     

基于新型太阳能空气源热泵供热系统的热泵性能研究

为进一步提高太阳能利用效率和太阳能辅助空气源热泵供热系统的性能,提出了一种新型太阳能空气源热泵供热系统,并研究了该供热系统的性能和特性.基于自行设计的10kW空气源热泵,建立了供热系统的数学模型,通过模拟得出了不同环境温度和出水温度下供热系统的运行特性和性能规律.结果表明：基于新型太阳能辅助空气源热泵供热系统,热泵的性能得到较大的提高.当环境温度为7℃时,空气源热泵的COP最大可增加26%.这为进一步研究新型太阳能辅助空气源热泵供热系统在供暖季节的性能奠定了基础.     

气泵在流体压强实验中应用几例

在高中物理实验中，气垫导轨广泛应用于牛顿运动定律，动量守恒定律等实验方面．而与气垫导轨配套的微音气泵，因其气流均匀，流量较大，使用方便，稍加改进可应用于初中物理流体压强教学中，使得实验现象更加明显，更加有趣，实验效果比较好．下面介绍几个实际应用供参考。     

Student error patterns as a function of curriculum design: teaching fractions to remedial high school students and high school students with learning disabilities

This study evaluated the relative effectiveness of a curriculum that incorporated three empirically derived principles of curriculum design with a basal approach in teaching basic fractions concepts to students with learning disabilities and other low performing students in high school remedial math classes. The components of effective mathematics instruction articulated by Good and Grouws (1979) were implemented in both conditions. Thus, the curriculum design variables were isolated by keeping all other aspects of instruction constant. Results indicated that, although both programs were reasonably successful in teaching the material, the curriculum program utilizing sophisticated principles of curriculum design was significantly more effective. Mean scores on a curriculum-referenced test were 96.5% for that group and 82.3% for the basal group. Secondary analyses of item clusters revealed that areas of weakness in the performance of the basal group could be directly linked to hypothesized flaws in its curriculum design.     

带一个回热器的Kalina循环的热力参数分析及优化

为了研究单一回热器对Kalina循环系统性能的影响,建立了带1个回热器的Kalina循环稳态数学模型,研究了循环的4个关键热力参数对Kalina循环净功和热效率的影响。对Kalina循环在不同热源温度下进行了热力参数优化,获得了循环在不同热源温度下的最大循环热效率。研究结果表明:在同一热源温度下,存在不同的最优蒸发器蒸发压力,使得循环净输出功和循环热效率分别达到最大值;循环净输出功和热效率随着蒸发器出口氨水溶液温度和氨水基本溶液浓度的增大而增大,随着透平背压的增大而减小;随着热源温度的增大,循环热效率逐渐增大,所对应的最优蒸发器蒸发压力和蒸发器出口氨水溶液温度逐渐增大,同时,透平背压和氨水基本溶液浓度逐渐降低。     

大体积混凝土施工的温度应力计算及裂缝控制

大体积钢筋混凝土具有结构厚,体形大,施工条件复杂和技术要求高等特点,除了要满足刚度强度和耐久性的要求以外,最突出的问题就是如何控制由于温度的变化而引起的混凝土开裂.本文以成都华晖公寓工程地下室施工为例,探讨了相关的温度应力计算和裂缝控制措施.     

大坝实测变形差值统计分析

环境量因子之间存在的相关性直接影响大坝安全监测统计分析的结果。基于某混凝土拱坝实测变形资料,采用差值统计分析方法对因子间的相关影响进行消除,并与常规逐步回归分析方法进行了对比。结果表明,差值统计分析在自动化监测采集条件下可达到逐步回归的精度并保证统计分析的可靠性。     

Experimental performance of moderate and high temperature heat pump charged with refrigerant mixture BY-3

Theoretical and experimental analysis of a new refrigerant mixture BY-3 was conducted based on a single-stage vapor compression refrigeration system. The water-water heat pump system used BY-3 to produce hot water when the low temperature was 20 ℃. The following results were obtained: the highest temperature at the condenser outlet reached about 85 ℃; when the difference between the water temperatures at the condenser outlet and the evaporator inlet was less than 40 ℃, the coefficient of performance (COP) was larger than 4; when the difference reached 55 ℃, the COP still kept 3; the discharge temperature of BY-3 was lower than 100 ℃, and the refrigerant vapor pressure kept lower than 1.8 MPa. When the water temperature at the condenser outlet reached over 85 ℃, nearly a 5 ℃ superheating temperature was maintained.     

A biometrical analysis of perceptions of family environment: a study of twin and singleton sibling kinships

Biometrical genetic analysis was applied to sibling and twin kinship data on 2 dimensions of perceived home environment. Correlations on 1 dimension, Restrictiveness-Permissiveness, were equal and significant for all kinships: MZ twins, DZ twins, same-sex siblings, and opposite-sex siblings significant for all 4 kinships: MZ twins, DZ twins, same-sex siblings, and opposite-sex siblings (r greater than .40). An E2-E1 biometrical model fitted Restrictiveness-Permissiveness, implying that treatments common to siblings create agreement about perceived environment. As intrapair differences were the same for all 4 kinships under this model, the equal environments assumption of the twin method was supported. In contrast, the Acceptance-Rejection dimension fitted a G-E1 model that makes the assumption that sibling similarity is the result of genetic factors and postulates an absence of shared environmental influences. This finding suggests that this aspect of home environment may depend as much on the child's inherited traits as on actual treatments and is in accord with the genetic analysis of individual traits in that developmentally effective environmental factors do not appear to be common to siblings.     

课堂提问类型与方式对高中生英语学习的影响及启示——基于一节高中英语优质课的观察与分析

本文对一节高中英语优质课提问进行了记录和分析并按照Anderson和Krathwohl的分类法将其归类,研究发现:分析层次的问题占了高中英语课堂的多数,契合了高中生思维的特点;教师的追问和反问能够引导学生更多的、质量更高的语言输出。     

Sex-related differences on a task of volume and density

A sex-related difference, favoring boys, was found on initial performance of two samples (one British, one American) of 10- and 11-year-old children on a task of volume and density. After a period of classroom instruction that included opportunities for children to interact with appropriate materials and each other, both boys and girls performed at a higher level on the task, but the difference between them remained the same. There was no indication of a sex-related difference other than a time lag, in pattern of development of the concept. The question of why there is a sex-related difference, which persists in spite of experience and instruction, is discussed.     

硝基苯生产中高浓度NOx尾气的处理方法研究

针对硝基苯废酸提浓尾气处理装置存在的问题,结合废酸提浓尾气处理装置改造实例,分别采用水、未提浓混酸和氢氧化钠溶液、水和双氧水串级做吸收剂。结果表明：采用压缩法脱除有机物气体和加压法水吸收、双氧水两级串联吸收氮氧化物气体的方法,对于尾气中浓度为130000～190000mg／m^3的苯、17～38mg／m^3的硝基苯和30～90×10^4mg／m^3的氮氧化物的平均脱除率可达99％以上。     

中美高等教育机构分类比较分析

中美高等教育机构分类在思想基础、指标体系、分类主体及分类功能等方面,既存在着共同的方面,也有差异。比如两国的分类都体现了“重学术”的价值取向,分类的标准都呈现出一元化的特点。不同的地方表现在我国的高等教育机构分类带有明显的行政性,分类的理论滞后于实践等方面。两国高等教育机构分类的差异是受本国的政治、经济和文化传统等因素影响的。     

The effectiveness of using computer simulated experiments on junior high students' understanding of the volume displacement concept

Several researchers have suggested that the computer holds much promise as a tool for science teachers for use in their classrooms (Bork, 1979, Lunetta & Hofstein, 1981). It also has been said that there needs to be more research in determining the effectiveness of computer software (Tinker, 1983). This study compared the effectiveness of microcomputer simulated experiences with that of parallel instruction involving hands-on laboratory experiences for teaching the concept of volume displacement to junior high school students. This study also assessed the differential effect on students' understanding of the volume displacement concept using sex of the students as another independent variable. In addition, it compared the degree of retention, after 45 days, of both treatment groups. It was found that computer simulated experiences were as effective as hands-on laboratory experiences, and that males, having had hands-on laboratory experiences, performed better on the posttest than females having had the hands-on laboratory experiences. There were no significant differences in performance when comparing males with females using the computer simulation in the learning of the displacement concept. This study also showed that there were no significant differences in the retention levels when the retention scores of the computer simulation groups were compared to those that had the hands-on laboratory experiences. However, an ANOVA of the retention test scores revealed that males in both treatment conditions retained knowledge of volume displacement better than females.     

高中化学教材难度的定量分析与评价——以三套化学教科书选修4之“溶液中的离子平衡”主题为例

以被全国中小学教材审定委员会审查通过的3套普通高中化学课程标准实验教科书<选修4(化学反应原理)>为研究对象,以<全日制普通高级中学化学课程标准(实验稿)>为参照系,利用课程难度定量模型对其中的重要知识主题--"溶液中的离子平衡"进行难度定量分析,从而为选择教科书与准确把握教学要求提供依据.     

增压吸收对土壤源吸收式热泵性能影响的模拟分析

针对土壤源吸收式热泵的性能对供热二次网回水温度较为敏感,提出采用压缩机增压的方式来提高吸收式热泵的吸收压力,进而提高土壤源吸收式热泵的高温性能。以LiBr-H_2O为工质对,模拟分析增压吸收对土壤源吸收式热泵高温性能的影响。结果表明,增压吸收可以有效降低吸收式热泵稀溶液的浓度,进而可以提高二次网回水温度,降低吸收式热泵的驱动热源温度。同时,随着增压比的升高,土壤源吸收式热泵供热系统的一次能源利用效率不断下降。     

Effects of finishing rolling temperatures and reduction on the mechanical properties of hot rolled multiphase steel

Effects of finishing rolling temperatures and reduction on the mechanical properties of hot rolled multiphase steel were investigated. Thermo-mechanical control processing (TMCP) was conducted by using a laboratory hot rolling mill, in which three different kinds of finishing rolling temperatures and reduction and various austempering times were applied. The results showed that polygonal ferrite, granular bainite and larger amount of stabilized retained austenite can be obtained by controlled rolling processes, and that the strain-induced transformation to martensite from the retained austenite can occur gradually when the steel is deformed during tensile test. Mechanical properties increase with decreasing finishing rolling temperature and increasing amount of deformation. The most TRIP (transformation induced plasticity) effect, and ultimate tensile strength (UTS), total elongation (TEL) and the product of ultimate tensile strength and total elongation (UTS×TEL) are obtained at 20 min.     

岩溶漏斗水库混凝土封底拱结构应力变形分析

为了研究堵漏工程中混凝土封底结构在水荷载、淤砂荷载以及温度荷载作用下的应力变形情况,进行有限元分析。结果表明:在茨竹湾水库库底岩采用混凝土拱结构进行封底,能够满足实际工程需要;各种工况下混凝土封底拱结构变形以及应力分布均匀,未出现应力集中区;沉降量最大出现在封底拱结构中心范围;最大拉应力主要分布在封底拱结构长轴方向断面两端顶部;最大压应力主要分布在封底拱结构短轴方向断面两端底部;拱结构底面到表面为升温工况将有利于其稳定;对封底拱结构轴断面四周进行针对性加厚处理,以满足拱结构的应力要求。     

高速磁浮轨道不平顺测试及分析

研究目的：提出高速磁浮轨道不平顺处理方法,分析不平顺特征,拟合形成轨道谱,为线路卒问维护提供参考。创新要点：实现了对高速磁浮轨道不平顺的提取,确定了轨道谱参数。研究方法：基于惯性基准法,运用数字信号处理方法实现对轨道不平顺的提取,采用最小二乘法拟合得剑定子向和导向面七参数轨道谱。重要结论：定子面和导向面分别在5-100m和10-100m波长范围内平顺性状态较好,由功能件安装等引起的1-5m和1—10m波长范围内的偏差应严格控制。     

Experimental study on the anti-jacking-up performance of a screw pile for photovoltaic stents in a seasonal frozen region

The soils in seasonal frozen regions freeze and thaw frequently, causing severe frost heave and thaw settlement problems, which bring challenges to piles of photovoltaic stents. In this paper, laboratory tests are conducted with different types of screw piles under freezing conditions, with also using smooth piles for contrast. The aim is to simulate the freezing process of screw piles according to practical working conditions based on the similarity principle. Internal thermal resistance is ignored. The change laws of temperature, displacement, as well as the influence factors of types of screw piles are analyzed. The results indicate that: with a freezing depth of 30 cm, which is half of the pile length, large-double-bladed screw piles perform the best in antijacking-up, while all-bladed screw piles perform the worst, independent of the types of soil samples tested. The fitting relationship between jacking-up displacement and freezing depth is also proposed for each type of pile. Results obtained can provide an important reference to site construction in seasonal frozen regions.