Synthesis and characterisation of n-octacosane@silica nanocapsules for thermal storage applications

This work reports the synthesis and characterisation of a core-shell n-octacosane@silica nanoencapsulated phase-change material obtained via interfacial hydrolysis and polycondensation of tetraethyl orthosilicate in miniemulsion. Silica has been used as the encapsulating material because of its thermal advantages relative to synthesised polymers. The material presents excellent heat storage potential, with a measured melting latent heat varying between 57.1 and 89.0 kJ kg⁻¹ (melting point between 58.2 ° C and 59.9 ° C) and a small particle size (between 565 and 227 nm). Degradation of the n-octacosane core starts between 150°C and 180°C. Also, the use of silica as shell material gives way to a heat conductivity of 0.796 W m⁻¹ K⁻¹ (greater than that of nanoencapsulated materials with polymeric shell). Charge/discharge cycles have been successfully simulated at low pressure to prove the suitability of the nanopowder as phase-change material. Further research will be carried out in the future regarding the use of the synthesised material in thermal applications involving nanofluids.     

Performance analysis of radial-inflow turbine of ORC: New combined approach of preliminary design and 3D CFD study

Journal of Mechanical Science and Technology - A new methodology for the aerothermodynamic design of radial-inflow turbines used in organic Rankine cycles is presented. Initially, a fully detailed...     

基于联合分簇和LASSO的室内指纹定位算法

为提高定位效率和定位精度,提出了一种基于联合分簇（Hybrid clustering, HC）和LASSO的室内定位算法。该定位算法首先利用簇匹配实现目标粗定位,再在簇内采用LASSO算法进行二次精确定位。通过基于接收信号强度（Received signal strength, RSS）信号特性的K中心聚类方法结合基于物理位置的联合分簇,来降低粗定位阶段的簇匹配错误以避免粗大误差。采用位置指纹RSS信号的覆盖向量的相似度作为分簇和簇匹配的准则来降低运算量。簇内定位阶段采用LASSO算法达到特征稀疏化,有利于目标节点存储空间和能耗的优化。在室内典型办公环境下的定位实验表明,本定位技术在降低在线匹配计算量的同时能保持良好的定位效果,在参考位置点间隔1.8 m时,平均定位误差为1.73 m。     

施工设备维修对工程进度影响的SD 模型及应用 ——以中亚某天然气管线建设工程为例

在现代建设工程中,施工设备维修对建设工程进度的影响日益增大,另一方面,工程实践中常见的赶工现象又可能导致设备超负荷运转,增加了维修管理的难度。系统动力学及相关软件为理顺施工设备维修与工程进度之间的关系、估计施工设备需求量提供了有效的工具。通过建立施工设备维修—工程进度联动模型,并使用该模型对某天然气管线建设工程进行模拟,发现在考虑施工设备维修的情况下,采用仿真方法,可以对多种方案进行有效的评估。     

Sorption-Desorption of Pyrene for Colombia and New Mexico Soils

The adsorption and availability of polycyclic aromatic hydrocarbons (PAHs) in the environment is an important factor to be considered for potential bioremediation processes. If desorption of the organic occurs, it could imply that remediation technologies such as microbial degradation may be feasible for PAH contaminated soils. Conversely no, or partial, desorption would indicate that the components may persist in the environment due to their decreased bioavailability. The sorption-desorption of pyrene in conjunction with two different soils was studied to determine the feasibility of bioremediation as an effective treatment. The measured distribution coefficient (K _d ) for the Colombia and New Mexico soils using a 4:40 soil:liquid ratio was 1956 and 526 L/kg, respectively. When the soil:liquid ratio was reduced to 1:40, the K _d values were 4294 L/Kg for the Colombia, and 1141 L/Kg for the New Mexico soil.     

绿波协调控制的子区动态划分算法

为了提高子区划分的效率,本文提出了一种基于绿波协调控制的二次划分子区的模型.首先,根据距离、流量和周期3原则,提出基于可协调度的粗划分指标对子区进行初次划分.然后,在最大绿波带优化模型的基础上,引进绿波带带宽达到率为细划分指标,对子区进行再次细划分,同时引入调整指数对子区进行在线调整,实现了子区划分及其信号配时参数优化的同步.最后,利用遗传模拟退火算法对子区划分方案快速寻优,实现了绿波协调控制的子区实时动态划分.通过算例分析表明,该控制方案能提高路网的通行能力,具有良好的稳定性和高效性.     

一种单频激光干涉仪非线性误差修正方法研究

针对单频激光干涉仪在位移测量中存在的非线性误差问题,研究了一种基于几何距离最小化的Heydemann修正算法,使用Jamin干涉仪和纳米位移台搭建了验证性实验。Jamin干涉仪是一种基于平面镜的差分结构单频干涉仪,当被测物体移动时,干涉仪输出两路相位差为90°的正交信号,这两路信号既用于Jamin干涉仪解算位移也用于验证论文的修正算法。实验结果表明,修正后的位移的拟合优度与Jamin干涉仪解算结果接近,决定系数约为1。相比Jamin干涉仪,在压电陶瓷同等驱动条件下,修正位移与电容传感器的位移的残差均较小,修正精度均高于Jamin干涉仪解算结果。