太阳能供热系统优化设计的相关问题研究

随着我国建筑总量和建筑能耗的快速增长,传统的供热方式已难以满足建筑供热的需求,而利用太阳能为建筑物供热,则可获得良好的节能和环保效益。就太阳能供热系统优化设计的相关问题进行了分析和研究,以期能为太阳能供热技术的推广和应用提供一定的理论依据。     

A DISTANCE MEASURE FOR CLASSIFYING ARIMA MODELS

Abstract. In a number of practical problems where clustering or choosing from a set of dynamic structures is needed, the introduction of a distance between the data is an early step in the application of multivariate statistical methods. In this paper a parametric approach is proposed in order to introduce a well-defined metric on the class of autoregressive integrated moving-average (ARIMA) invertible models as the Euclidean distance between their autoregressive expansions. Two case studies for clustering economic time series and for assessing the consistency of seasonal adjustment procedures are discussed. Finally, some related proposals are surveyed and some suggestions for further research are made.     

Information systems use as strategy practice: A multi-dimensional view of strategic information system implementation and use

Information systems (IS) are strategic in so far as they are used to realize strategic intent. Yet, while much has been said about aligning IS functionality with the strategic intent and how to organizationally implement strategically aligned systems, less is known of how to successfully implement strategic change associated with system use – a truly critical challenge within strategic IS implementation. Drawing on a strategy-as-practice perspective we address this gap by developing a multi-dimensional view of IS strategy, conceptualizing three key challenges in the IS strategy process, to explain how and why a paper mill, despite successfully implementing a strategic production management system, failed to produce intended strategic change. We call this outcome strategy blindness: organizational incapability to realize the strategic intent of implemented, available system capabilities. Using a longitudinal case study we investigate how cognitive rigidity of key actors and fixed, interrelated practices shaped the implementation of the new production system. We also identify core components and dynamics that constitute a richer multi-dimensional view of the IS strategy implementation (alignment) process. In particular, we identify three salient factors that contribute to strategy blindness – mistranslation of intent, flexibility of the IT artifact and cognitive entrenchment – and discuss how they affect strategic implementation processes. We conclude by discussing implications of our findings for IS strategy theory and practice, especially the contribution of strategy-as-practice to this stream of research.     

导热增强聚氨酯基柔性定形相变材料的制备及性能

以聚乙二醇（PEG10000）和氨丙基封端的聚二甲基硅氧烷（APDMS）为软段，以甲苯-2,4-二异氰酸酯（TDI）为硬段，以碳纳米管（CNTs）作为功能性材料，一锅法制备了导热增强的聚氨酯基柔性定形相变材料（PU/APDMS/CNTs）。用FTIR、XRD、DSC和TGA等对材料的结构特征和热性能进行了表征。当APDMS含量为10 wt%时，PU/APDMS/CNTs的相变焓值为88.3 J/g，该相变材料在200℃内不发生热分解，具有良好的热稳定性和定形效果，加入5 wt% CNTs的柔性定形相变材料，能够实现光热转换和热能存储，其光热转换和热能存储效率为62.8%，与未加入CNTs的相变材料相比，导热性能明显增强，其升降温速率提高了2.75倍。     

Fe doping effect on EuTiO3: The magnetic properties and giant magnetocaloric effect

The magnetic properties and magnetocaloric effect for EuTi_1-xFe_xO₃ (x = 0.05, 0.1) compounds are investigated. When a part of Ti⁴⁺ions were substituted by Fe ions, the AFM ordering can be significantly changed to be FM. The EuTi_1-xFe_xO₃ (x = 0.05, 0.1) compounds exhibit a PM to FM transition with decreasing temperature and the Curie temperature is 6 K. Under the field changes of 1 T, and RC are valued to be 10.1 J/kg K and 50.2 J/kg for EuTi_0.95Fe_0.05O₃; 9.6 J/kg K and 47.7 J/kg for EuTi_0.9Fe_0.1O₃, without magnetic and thermal hysteresis. RC is almost twice as much as EuTiO₃ (27 J/kg) as substitution of Fe³⁺ ions for Ti⁴⁺ions, which may be attributed to the magnetic transition (AFM to FM). Therefore, the giant and large RC suggest the EuTi_1-xFe_xO₃ compounds are good materials for magnetic refrigerant.     

Subsoil <Superscript>15</Superscript>N-N<Subscript>2</Subscript>O Concentrations in a Sandy Soil Profile After Application of <Superscript>15</Superscript>N-fertilizer

Studies on emissions of nitrous oxide (N₂O) from agricultural soils mostly focus on fluxes between the soil and the atmosphere or are limited to the atmosphere in the topsoil. However, in soils with shallow water tables, significant N₂O formation may occur closer to the groundwater. The aims of this study were (i) to determine the importance of subsoil N₂O formation in a sandy soil; and (ii) to obtain a quantitative insight in the contribution of subsoil N₂O to the overall losses of N₂O to the environment. We applied ¹⁵N labeled fertilizer at a rate of 5.22 kg ¹⁵N ha⁻¹; 50% as Ca(NO₃)₂ and 50% as NH₄Cl, on a mesic typic Haplaquod seeded with potatoes (Solanum tuberosum L.), and traced soil N₂O concentrations and fluxes over a one-year period. Throughout the year, total N₂O and the amount of ¹⁵N recovered in soil N₂O were highest in the subsoil, with a maximum concentration at 48 cm depth in mid-February of 19900 μl m⁻³ and 24 μg ¹⁵N m⁻³, respectively. The maximum concentration coincided with the highest water-filled pore space of 71%. The cumulative flux of N₂O was 446 g N₂O-N ha⁻¹, the recovery of ¹⁵N in this flux was 0.06%. During the summer, maximum fluxes followed high soil N₂O concentrations. During winter, no such relation was found. We concluded that the formation of N₂O was the highest in the subsoil, largely controlled by water-filled pore space rather than NO₃⁻ concentration or temperature. Although high subsoil N₂O concentrations did not lead to high surface fluxes of N₂O in the winter, artificial draining may lead to high indirect N₂O emissions through supersaturated drainage water.     

Composition and seasonal variation of fatty acids of <Emphasis Type="Italic">Diplodus vulgaris</Emphasis> L. from the Adriatic Sea

Muscle tissue from the common two-banded sea bream Diplodus vulgaris L. originating from the Adriatic Sea, Croatia, was analyzed. The FA composition of neutral (TAG) and polar (PE, PC, PI/PS) lipid classes was determined, as well as the lipid and water contents during winter and summer periods. Both the total lipid and water contents were higher in the winter period. We identified 16 different FA. The major constituents of the total FA in both seasons were saturates: palmitic (16∶0) and stearic acids (18∶0); monoenes: oleic (18∶1n−9) and palmitoleic acids (16∶1n−7); and polyunsaturates: arachidonic acid (20∶4n−6), EPA (20∶5n−3), and DHA (22∶6n−3), but their amounts and ratios differed significantly between the two seasons and between lipid fractions. The FA composition showed a noticeable pattern of seasonality that reflected fluctuations mainly in TAG. The diminution of the monounsaturated FA content in the summer was clearly followed by an increase in PUFA content. Diplodus vulgaris is a good source of natural n−3 PUFA and would therefore be suitable for inclusion in highly unsaturated low-fat diets.     

2H-MoS2定向调控生成1T-MoS2及应用

MoS2因其独特的二维“三明治”层状结构在电学、能源和催化等行业备受关注。由于S、Mo原子配位模式的不同，MoS2主要以1T和2H相两种形式存在。通常，1T-MoS2拥有更大的层间距和更多的催化活性位点，在许多领域都表现出了比2H-MoS2更优异的性能。通过控制2H-MoS2 中S平面的横向位移和Mo 的3d轨道电子填充状态，可以定向调控2H-MoS2生成1T-MoS2。鉴于此，综述了2H-MoS2定向调控制备1T-MoS2的研究进展，并对影响调控过程的主要因素及相应的调控方法和机理进行了详细的阐述，同时总结了1T-MoS2在析氢、电池、光和热催化领域的应用，可为1T-MoS2的定向合成与应用打下一定的基础。另外，也对 1T-MoS2在未来的实际应用前景进行了展望。     

2020年中国低碳能源中期目标解读

提出了关联能源强度ε与碳强度κ的一个新的能源经济参数—能源碳强度ω;并用以核算、澄清了中国政府宣布的2020年"节能(降低ε)"与"减排(CO2)"两个目标之间的关系.估算出了到2020年中国能源消耗为41亿吨标煤、人均2.93吨标煤、能源弹性系数0.5,二氧化碳排放量不超过76亿吨、占世界24.7%的目标数据;指出了实现这一宏伟目标的最重要途径:除快速发展非化石能源和煤的CCS利用外,就是产业转型和发展天然气冷热电联供能源系统,大幅度提高能效.