GaAlAs/GaAs双异质结发光管中的深能级

本文用DLTS谱仪和单脉冲瞬态电容技术测量了光通信用GaAlAs/GaAs双异质结发光管中的深能级,对有源区掺Si和掺Ge的相同结构器件,均测得有多子陷阱存在,其能级位置分别为E_C—E_D≈0.29eV和E_T—E_V≈0.42eV。比较了外延系统中氧含量变化对有源区掺Si器件深能级的影响,以及有源区EL图象中的DSD与深能级关系,结果表明外延系统中氧含量对深能级有明显影响,而EL图象中DSD的出现率与深能级无明显关系。     

深部巷道裂隙围岩危险体判定及应力监测预警

工程岩体是由节理、裂隙等结构组成的不连续介质体,深部巷道处于高地压、强扰动的复杂工程环境中,裂隙岩体的稳定性是深部工程安全稳定性研究的重要课题。本文以矿井深部巷道为研究对象,构建离散裂隙网络模型,获得等效岩体参数,并以此建立裂隙岩体工程模型;分析工程巷道裂隙围岩的应力、变形和破坏特征。模拟试验结果表明:斜联巷、釆联巷、水仓与主运输巷交叉等位置是应力集中区,易产生张拉、剪切破坏;根据数值模拟获得的应力集中危险区域分布特点,布设围岩应力监测网络,成功预警位于斜联巷和水仓连接巷的顶板塌落事故,为矿山设备、人员安全提供了可靠的保障。     

Metal chlorides-promoted ammonia absorption of deep eutectic solvent

Ammonia is considered as a promising hydrogen or energy carrier. Ammonia absorption or adsorption is an important aspect for both ammonia removal, storage and separation applications. To these ends, a wide range of solid and liquid sorbents have been investigated. Among these, the deep eutectic solvent (DES) is emerging as a promising class of ammonia absorbers. Herein, we report a novel type of DES, i.e., metal-containing DESs for ammonia absorption. Specifically, the NH₃ absorption capacity is enhanced by ca. 18.1–36.9% when a small amount of metal chlorides, such as MgCl₂, MnCl₂ etc., are added into a DES composed of resorcinol (Res) and ethylene glycol (EG). To our knowledge, the MgCl₂/Res/EG (0.1:1:2) DES outperforms most of the reported DESs. The excellent NH₃ absorption performances of metal–containing DESs have been attributed to the synergy of Lewis acid–base and hydrogen bonding interactions. Additionally, good reversibility and high NH₃/CO₂ selectivity are achieved over the MgCl₂/Res/EG (0.1:1:2) DES, which enables it to be a potential NH₃ absorber for further investigations.     

Thermoelastic Response of Cross-Ply Laminated Shells Based on a Rigorous Shell Theory

Thermal deformations in cross-ply laminated shells are investigated. The state space approach is used to generate exact solutions for the thermoelastic response of cross-ply spherical, cylindrical and doubly curved shells for various boundary conditions and subjected to general temperature field. The shells possess two parallel edges simply supported and the remaining ones having any possible combination of boundary conditions: free, clamped or simply supported. A rigorous thick deep first order shear deformation shell theory is used in the analysis. Deflections are computed for shells with various boundary conditions undergoing uniform and linearly varying temperature through the thickness. The exact solutions for thermal deflections can be used as benchmarks for approximate solutions such as Rayleigh-Ritz and finite element methods.     

Thermal Buckling of Imperfect Deep Functionally Graded Spherical Shell

Thermal buckling analysis of deep imperfect functionally graded (FGM) spherical shell is considered in this paper. A mixture of ceramic and metal is considered for the FGM shell and the material properties, such as the modulus of elasticity and coefficient of thermal expansion, vary by a power law function through the thickness. Employing the Sanders non-linear kinematic relations, total potential energy function is derived and the equilibrium and stability equations are obtained for the imperfect shell. Approximate solutions satisfying the simply supported boundary condition are assumed and using the Galerkin method the error due to the approximation is minimized. The geometrically imperfect shell is considered and three types of thermal loadings, such as the uniform temperature rise (UTR), linear temperature rise through the thickness (LTR), and non-linear temperature rise through the thickness (NLTR) are considered and their associated buckling temperatures are obtained. The effects of different temperature functions and the magnitude of initial geometric imperfection are examined on the thermal buckling loads of the shell.     

A data-driven digital-twin prognostics method for proton exchange membrane fuel cell remaining useful life prediction

Prognostics and health management of proton exchange membrane fuel cell (PEMFC) systems have driven increasing research attention in recent years as the durability of PEMFC stack remains as a technical barrier for its large-scale commercialization. To monitor the health state during PEMFC operation, digital twin (DT), as a smart manufacturing technique, is applied in this paper to establish an ensemble remaining useful life prediction system. A data-driven DT is constructed to integrate the physical knowledge of the system and a deep transfer learning model based on stacked denoising autoencoder is used to update the DT with online measurement. A case study with experimental PEMFC degradation data is presented where the proposed data-driven DT prognostics method has applied and reached a high prediction accuracy. Furthermore, the predicted results are proved to be less affected even with limited measurement data.     

利用费托合成制取液体燃料的研究进展

费托合成可以用煤基合成气、天然气以及生物质气等为原料来制取液态燃料.该合成反应的催化剂有铁催化剂和钴催化剂,铁催化剂具有高时空产率,而钴催化剂具有较高的选择性和稳定性.费托合成的机理目前还没有统一说法,对几种比较流行的机理做了简单介绍.费托合成的设备有固定床反应器、流化床反应器和浆态床反应器,从发展趋势来看,浆态床是F-T合成反应器的主要发展方向.     

5MW低功率堆主屏蔽设计与安全分析

本文介绍了5MW 低功率堆(5MW LPR)主屏蔽辐射场和温场的计算模型、方法和程序,给出了修改设计的主要计算结果。混凝土屏蔽层内表面的入射中子通量和γ通量均满足设计标准规定。最高温度、最大温升及最大温度梯度亦均符合规定要求。为证明温场程序的可靠性,将HFETR 混凝土屏蔽层内温度计算值与实测值作了比较,结果符合得很好。     

5MW低功率堆物理启动

本文介绍5MW 低功率堆(5MW LPR)首次装料及首次临界试验。由于本堆使用有燃耗的燃料元件,铍作反射层,光激中子成为强的内中子源,其强度随着燃料元件装量的增加而增加。因此,装料时元件法外堆结果有较大的涨落,但整个装料过程是安全的。在次临界下,做了控制棒相对效率曲线,然后,提升控制棒,进行计数外推,达到首次临界。     

清华大学5MW核供热站的过程计算机系统

本文讨论了清华大学5MW 核供热站主控室中过程计算机系统的设计、功能、应用及其与传统仪表系统的关系,描述了该过程计算机系统的硬件配置。该计算机系统是一个具有自动故障诊断和自动切换功能的双机系统,所用计算机为 PDP11/73。还简单介绍了所用智能化、加固的数据站IMP 和专门研制的实时数据显示画面辅助生成系统的基本思想。