智慧居家养老服务系统设计研究

目的在复杂社会化网络中,灵活运用社会生活产生的大数据,构建设计、技术与管理相结合的智慧居家养老服务系统,解决碎片化的养老服务与多样化的养老需求之间匹配度低的问题。方法将服务设计思维引入养老领域,在调研的基础上归纳居家养老服务生态。借助利益相关者价值网络和服务流程图这两种服务设计可视化工具,剖析科技介入的居家养老服务中存在的服务触点及其关联。结论重新组织智慧居家养老服务的关键触点,提出智慧居家养老服务系统架构,形成养老服务资源、养老生活动态信息和养老服务三者联动的持续性发展链路,有利于合理把握老龄人口需求,提升用户体验,为智慧居家养老体系的创新提供设计学视角的参考。     

Highly Stable Sb/C Anode for K+ and Na+ Energy Storage Enabled by Pulsed Laser Ablation and Polydopamine Coating

Potassium- and sodium-ion batteries (PIBs and SIBs) have great potential as the next-generation energy application owing to the natural abundance of K and Na. Antimony (Sb) is a suitable alloying-type anode for PIBs and SIBs due to its high theoretical capacity and proper operation voltage; yet, the severe volume variation remains a challenge. Herein, a preparation of N-doped carbon-wrapped Sb nanoparticles (L-Sb/NC) using pulsed laser ablation and polydopamine coating techniques, is reported. As the anode for PIB and SIB, the L-Sb/NC delivers superior rate capabilities and excellent cycle stabilities (442.2 and 390.5 mA h g⁻¹ after 250 cycles with the capacity decay of 0.037% and 0.038% per cycle) at the current densities of 0.5 and 1.0 A g⁻¹, respectively. Operando X-ray diffraction reveals the facilitated and stable potassiation and sodiation mechanisms of L-Sb/NC enabled by its optimal core–shell structure. Furthermore, the SIB full cell fabricated with L-Sb/NC and Na₃V₂(PO₄)₂F₃ shows outstanding electrochemical performances, demonstrating its practical energy storage application.     

跟踪锁相技术在电力电量交流采样中的应用

在电力电量测量中,目前多以微处理器为核心,根据交流采样原理设计,对电力线上的电流,电压进行瞬时采样,由电工基本原理公式进行计算,求出电力线上各种的数值并进行显示和记录,同时可以经过ＲＳ－２３２Ｃ通讯口远传,实现电量的数据测量。     

基于智能合约的物联网访问控制架构与验证

针对传统的访问控制方法存在单点故障,不能提供可信、安全、动态化权限管理的问题,提出了一种面向无线传感器网（WSN）的基于区块链和智能合约的新型访问控制方法,以解决现有的基于区块链的访问控制方法存在的访问动态化、智能化水平不高等问题。首先,提出一种基于区块链的新型访问控制管理架构,降低网络运算开销;其次,搭建多层次智能合约体系,设计代理合约（AC）、权限管理合约（AMC）和访问控制合约（ACC）,以实现对WSN的可信化、动态化的权限管理;最后,采用基于径向基函数（RBF）神经网络的动态权限生成算法,并结合访问政策动态生成访问节点的信用度阈值,实现面向WSN海量传感器的智能化、动态化的访问控制管理。实验结果表明,所提模型在WSN安全访问控制应用上具有可行性、安全性和有效性。     

Carboxymethylchitosan + Cu mixture as an inhibitor used for mild steel in 1 M HCl

The inhibition effect of Carboxymethylchitosan (CMCT), Cu²⁺, and CMCT + Cu²⁺ mixture on the corrosion of mild steel in 1 M HCl has been investigated using gravimetric and electrochemical techniques. CMCT + Cu²⁺ mixture acts much more effectively than the inhibiting action of each additive separately. In addition, higher efficiency is achieved for the mixture of 20 mg L⁻¹ CMCT + 10⁻⁴ M Cu²⁺. The efficiency of the optimal mixture increases with the temperature in the range 298-353 K. Activation energy of corrosion reaction in the presence of the optimal mixture of the inhibitors is much lower than that exhibited in 1 M HCl solution. The inhibition mechanism proposed in this paper is based on the results of conductometric investigations.     

移动机器人自适应行为选择的混沌特性分析

针对移动机器人运行环境的复杂非线性特性,提出一种将重构相空间理论应用到移动机器人自适应行为选择中的混沌非线性分析方法。在所采集的一维自适应行为动作选择随机序列的基础上,重构时间序列的相空间,并计算相空间的嵌入维数、混沌吸引子和最大Lyapunov指数。计算结果表明,当运行环境中障碍物的分布密度较大时,移动机器人的自适应行为选择规律呈现混沌特性。这为结合混沌理论,给移动机器人的自适应行为选择提供更精确的控制,提供了理论基础。     

High‐temperature DSC study of polyacrylonitrile precursors during their conversion to carbon fibers

The evolution of structure, the changes of properties during the preoxidation, precarbonization, and carbonization of different polyacrylonitrile (PAN) precursors were firstly studied in detail by means of using high‐temperature differential scanning calorimetry (DSC) to characterize with continuous heating from 25 to 1400°C. It was essential to study the thermal behavior of PAN precursors so that proper temperature was determined. Three precursors with different composition, P1: acrylonitrile/itaconic acid (AN/IA) = 98/2 (wt/wt); P2: acrylonitrile/acrylamide (AN/AM) = 98/2 (wt/wt); P3: acrylonitrile/ammonium salt of itaconic acid (AN/AIA) = 98/2 (wt/wt) were, respectively, selected in this study. Comparative results of the DSC curves showed that the heating history influenced greatly the heat quantities released and exothermic position at low temperature of DSC curve, but influenced slightly at higher temperature. Aromatic index, carbon yield (W_c) and weight loss (η) can be calculated. After adjusting the temperature in preoxidation and precarbonization and carbonization technology depending on high‐temperature DSC, the high performance carbon fibers were obtained that tensile strength is 3.56–4.16 GPa, modulus is 235–243 GPa. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Optimized pore structure and high permeability of metakaolin/fly-ash-based geopolymer foams from Al– and H2O2–sodium oleate foaming systems

Geopolymer foams have been widely studied as adsorbents owing to their high specific surface areas, high heavy metal immobilization efficiencies, low cost, environmental friendliness, and resource-recycling benefits. In this study, geopolymer foams with different pore structures were prepared from Al– and H₂O₂–sodium oleate foaming systems, and their chemical properties, pore structures, and permeabilities were characterized. The effects of the foaming agent type and surfactant content on the crystal structure and chemical bonding of the materials were analyzed by X-ray diffraction analysis and Fourier-transform infrared spectroscopy, and the pore morphology and structural characteristics were characterized by morphological observations, three-dimensional (3D) reconstruction, and compression tests. Numerical simulations were also carried out to study the structural characteristics of the 3D-reconstructed pores. Furthermore, variations in the permeability coefficient and flow characteristics were tested and analyzed by experiments and simulations. The pores in the geopolymer from the H₂O₂–sodium oleate foaming system tended to be more connected, whereas those in the Al–sodium oleate geopolymers were more complete and closed. The highly connected pore structure facilitates the even diffusion of the solution and effectively increases the amount of adsorption sites. These properties are significant for adjusting the adsorption capacity of geopolymer foams as adsorption monoliths.     

Computer simulation of reactive extrusion processes for free radical polymerization

The reactive extrusion for polymerization is an integrated polymer processing technology. A new semi‐implicit iterative algorithm was proposed to deal with the complicated relationships among the chemical reaction, the macromolecular structure and the chemorheological property. Then the numerical computation expressions of the average molecular weight, the monomer conversion, and the initiator concentration were deduced, and the computer simulation of the reactive extrusion process for free radical polymerization was carried out, on basis of which reactive processing conditions can be optimized. POLYM. ENG. SCI., 47:667–674, 2007. © 2007 Society of Plastics Engineers.     

孔道成孔工艺对锚固力损失的分析与控制

预应力锚索锚固作用机理复杂,影响预应力锚固效果的因素众多,锚固力损失与材料性质、被锚固介质力学特性、锚夹具质量、施工工艺等因素有关.研究了锚索施工工艺中孔道成孔工艺对锚索锚固力损失的影响及控制措施,通过数学手段分析了孔道弯曲和孔道偏差影响,推导出了孔道摩擦损失理论计算公式.研究表明:孔道摩擦损失理论计算公式更加符合工程实际,具有较大的实用价值;钻孔的孔斜率与锚固力沿程损失具有相关性,孔斜率越大,锚索锚固力损失也越大,在相同的孔斜率n条件下,锚索张拉荷载P越大锚固力损失也越大;通过相应的工程措施可以减少孔道成孔引起的锚固力损失.