三种标准天空分量叠加的天空亮度模型构建

天空亮度分布是研究建筑采光的基本资料。研究建筑动态采光要求量化年周期内天空亮度动态分布,本课题提出了通过三种标准天空亮度分布模型的分量进行叠加以近似拟合某时刻天空实际亮度分布的构想,并以此为基础建立动态天空亮度模型。本文主要介绍了三种标准天空确立的研究方法、分量叠加方式及该模型校验测试方式。     

煤层气的压力对液化流程性能的影响

分析了原料气进冷箱压力对制冷剂组份、流量、压缩机功耗、冷却水的冷却量的影响.计算结果表明,对于特定的冷箱,原料气进冷箱的压力对制冷剂的组分、流量及压缩机功耗产生重要影响.     

Preliminary design and analysis of a cubic deployable support structure based on shape memory polymer composite

The deployable structures based on shape memory polymer composites (SMPCs) have been developed for its unique properties, such as high reliability, low-cost, lightweight, and self-deployment without complex mechanical devices compared with traditional deployable structures. In order to increase the inflatable structure system’s robustness and light the weight of it, a cubic deployable support structure based on SMPC is designed and analyzed preliminarily. The cubic deployable support structure based on SMPC consists of four dependent spatial cages, each spatial cage is composed of 12 three-longeron SMPC truss booms and end connections. The shape recovery of arc-shaped deployable laminates drive the three-longeron SMPC truss booms to unfold, thus realize the expansion of the deployable support structure. The concept and operation of the cubic deployable support structure are described in detail. A series of experiments are performed on the three-longeron deployable laminates unit and the simplified cubic deployable support structure to investigate the shape recovery behavior in the deployment process. Results indicate that the cubic deployable support structure has a high deployment-tgo-stowage volume ratio and can achieve self-deployment, package, and deploy without complex mechanical devices.     

Nb微合金化对Cr-Ni-Mo-V系高强钢组织及力学性能的影响

对含Nb与不含Nb的Cr-Ni-Mo-V系高强钢进行880℃×1 h淬火+300℃×3 h回火处理,并采用SEM、EBSD、TEM和物理化学相分析等技术分别对其微观组织和析出相进行观察分析。结果表明,添加了0.035%Nb的试验钢组织得到细化,马氏体板条块尺寸从3.1μm下降至2.9μm,且Nb的添加使得MC型析出相的含量增加,析出相尺寸分布得到优化,尺寸在18～200 nm的析出相含量明显增加。由于析出相含量的增加,固溶C含量有所下降,加之含Nb试验钢中的原始C含量稍低,导致含Nb钢的强度稍有下降,但仍达到2000 MPa水平。而马氏体组织的细化及析出相尺寸分布的优化使含Nb试验钢韧性明显提升,室温和-40℃低温冲击吸收能量(KU₂)均提高至44 J。     

道次压下量对2197铝锂合金轧制组织与力学性能的影响

针对铝锂合金塑韧性、成形性差的问题,本工作通过OM/SEM微观组织分析、拉伸及硬度/电导率测试,研究了在总压下量75%条件下、轧制道次压下量(即10%、30%、30%+60%,分别对应小、中、大道次压下量)对2197铝锂合金组织与力学性能的影响。结果表明：道次压下量显著影响铝锂合金的晶粒结构、析出相的数量及分布。轧制态合金的强度随单道次轧制压下量的增加而显著增加、而塑韧性则明显下降。T8时效处理使析出相大量析出,轧制合金中的Portevin-Le Chatelier(PLC)效应得到消除,小、大道次压下量轧制合金的力学性能得到显著提升。大压下量轧制合金经时效处理后强塑性综合力学性能最高,抗拉强度为384.94 MPa、断后伸长率为12.45%,较小、中道次压下量轧制时效合金分别提高2%、21%和29%、31%。     

Fe-4Mn-1.5Al-0.5Si-0.2C-0.05Nb中锰钢的热变形行为研究

针对较高Mn含量会导致中锰钢成本提高、出现偏析而限制其应用的问题,设计了一种能够满足1 000 MPa级别性能要求(抗拉强度R_m>1 000 MPa,总伸长率A>30%)的中锰钢,其成分为Fe-4Mn-1.5Al-0.5Si-0.2C-0.05Nb。通过绘制实验钢在不同应变速率和变形温度下的真应力-真应变曲线,并结合组织观察,研究了实验钢的热变形行为,尤其是应变速率和变形温度对实验钢热变形行为的影响规律,并最终获得了实验钢的动态再结晶图和本构方程。结果表明：变形温度的降低和应变速率的提高均会抑制动态再结晶的发生;低应变速率(0.1 s^-1)下的所有样品均会发生完全动态再结晶;中应变速率(1 s^-1)下,变形温度为800℃的样品只发生部分动态再结晶;高应变速率(10 s^-1)下,不发生完全动态再结晶的变形温度扩大至800～950℃;实验钢的本构方程为■。动态再结晶图和本构方程的确定对实际生产中轧制工艺的设计、得到具备优良性能的特定类型的微观组织具有重要意义。     

GIS支持下的矿区土壤含水量遥感反演及变化规律

遥感方法可以开展大范围土壤含水率的连续监测,其技术关键是建立土壤含水率的遥感信息模型.针对矿区采动影响特征,提出了应用归一化植被指数NDVI=0.3作为判别高、低植被覆盖条件的阈值;裸地或低植被覆盖条件(NDVI≤0.3)采用基于热惯量理论的表现热惯量法(ATI)、高植被覆盖条件(NDVI＞0.3)采用作物供水指数法(VSWI)来反演土壤含水量.并根据采后"三带"高度和植被覆盖情况,将矿区分为6种不同的研究区域,提出应用MODIS数据和TM/ETM 数据定量反演矿区土壤含水量,进一步提出了在GIS支持下,由非采煤区推算采煤区采矿前的土壤含水量以及分析采矿前后土壤含水量变化规律的理论和方法.     

磁珠分选原理与分选试验研究

在对磁珠的磁选原理和磁选动力学分析的基础上，得出了磁珠在磁场中所受磁力和从磁选机中分离出磁珠所需磁力的计算公式，给出了不同分选次数和分选工艺的分选效果，得出了采用弱磁场磁选机能够有效回收粉煤灰中磁珠的重要结论。     

Site-selective occupation and luminescence property investigation of Ca18Na3Y(PO4)14:Eu2+ phosphor for full-spectrum LED

Cyan-emitting phosphors have attracted widespread attention as an integral part to realize full-spectrum lighting. Understanding the site occupation of luminescence centers is of great importance to design and clarify the luminescent mechanism for new cyan-emitting phosphors. Here, we report a cyan-emitting phosphor Ca₁₈Na₃Y(PO₄)₁₄:Eu²⁺ synthesized by the high-temperature solid-state method. The crystal structure is characterized by X-ray diffraction and refined by the Rietveld method. The diffuse reflectance spectra, excitation/emission spectra, fluorescence decay curves, thermal stability, and related mechanism are systematically studied. The results show that Ca₁₈Na₃Y(PO₄)₁₄:Eu²⁺ crystallizes in a trigonal crystal system with space group R3c. Under excitation at 350 nm, a broadband cyan emission can be obtained at 500 nm with a half-width of about 120 nm, which is caused by Eu²⁺ occupying five different sites in host, namely, Na2O₁₂ (450 nm), (Ca3/Na1)O₈ (485 nm), Ca2O₈ (515 nm), Ca1O₇ (565 nm), and (Ca4/Y)O₆ (640 nm), respectively. Moreover, crystal structure, room and low temperature spectroscopy, and luminescence decay time are used to skillfully verify the site-selective occupation of Eu²⁺. Finally, a full-spectrum light-emitting diode (LED) lamp is fabricated with an improved color rendering index (∼90.3), CCT (∼5492 K), and CIE coordinates (0.332, 0.318). The results show that Ca₁₈Na₃Y(PO₄)₁₄:Eu²⁺ has the potential to act as a cyan emission phosphor for full-spectrum white LEDs.     

关于天然气管网安全掺氢比10%的商榷

大力发展氢能是实现“碳达峰、碳中和”目标的重要途径之一。将氢气掺入现有天然气管网利于实现氢能经济高效、大规模输送与应用。安全掺氢比是掺氢天然气管输系统有待解决的关键问题之一。有观点提出当掺氢天然气中的掺氢比在10%以下时,可无需加以验证地直接通过天然气管网输送。本文提出从目前来看,该观点不成立。文章从管网系统掺氢适应性、示范项目掺氢比探讨和标准规范3个方面阐述了个中缘由。文中指出,掺氢天然气管输技术正处于起步阶段,其安全保障还面临诸多挑战,任何结论都需要经过反复论证和验证,以稳步推动氢能产业发展。