Simple,extensible and flexible random key predistribution schemes for wireless sensor networks using reusable key pools

Sensor nodes are tiny, low-power, computationally limited and battery constrained electromechanical devices. A sensor node contains a sensing unit and a wireless communication unit. Sensor nodes are deployed over a field for sensing an event data in the environment and transfer it towards a base station over its wireless channel. In a typical application, vast amount of sensor nodes are deployed over a field which constitute a sensor network. Sensor nodes must be customized for a specific sensor network application before the deployment. This customization is needed not only for underlying networking application, but also for security related configurations. Random key predistribution mechanisms have been proposed to provide security for wireless sensor networks. In the literature, there are well known random key predistribution schemes. Some of these schemes are secure, but quite complex to apply in real-world applications due to their node-based customization requirements, while some other are easily applicable but they do not offer reasonable security. In this paper, we propose random key predistribution schemes for wireless sensor networks that provide varying ranges of security. The proposed schemes are easily applicable in real world scenarios due to their simplicity and relaxed node customization requirements. In this respect, our schemes provide a tradeoff. Moreover, our proposed schemes show a good extensibility property. We assume prior deployment knowledge. We examine performance of our schemes and compare them with well known random key predistribution schemes.     

Micromilling of microbarbs for medical implants

Successful application of many implantable medical devices often depends on the technique used for attaching the devices to living tissue. Although mechanical attachment techniques that use micro-scale piercing elements are very promising, the fabrication of the micro-scale piercing elements poses considerable challenges. In this paper, the use of the mechanical micromilling process for fabrication of micro-scale piercing elements (microbarbs) from biocompatible materials is investigated. Two micro-scale milling tools with custom geometries are used during the fabrication. To gain an understanding of the process conditions on the performance metrics of micromilling forces, surface roughness, and burr formation, a design of experiments study is performed on polymethyl methacrylate (PMMA). The geometric capability of the process is demonstrated by fabricating PMMA microbarbs with different sizes (widths from 68 to ), edge sharpnesses (60 and 90 included angles), and heights (from 84 to ). The capability to micromill a variety of biocompatible materials is demonstrated by creating microbarbs from non-biodegradable 304 stainless steel and PMMA, from bioresorbable polylactic acid (PLA), and from a fibrin based plastic. It is concluded that the micromilling process can be used for effectively fabricating arrays of microbarbs.     

Ranging in a Single-Input Multiple-Output (SIMO) System

In this letter, optimal ranging in a single-input multiple-output (SIMO) system is studied. The theoretical limits on the accuracy of time-of-arrival (TOA) (equivalently, range) estimation are calculated in terms of the Cramer-Rao lower bound (CRLB). Unlike the conventional phased array antenna structure, a more generic fading model is employed, which allows for the analysis of spatial diversity gains from the viewpoint of a ranging system. In addition to the optimal solution, a two-step suboptimal range estimator is proposed, and its performance is compared with the CRLBs.     

A Generic Model to Solve Tactical Planning Problems in Flexible Manufacturing Systems

This paper is an attempt to develop a generic modeling framework that addresses tactical planning problems of flexible manufacturing systems in a coherent manner. We propose a generic 0-1 mixed integer programming formulation, that integrates batching, loading, and routing problems with their critical aspects related to a system's performance. For this purpose, a thorough analysis is made to determine and relate system components, their attributes, and alternatives together with performance measures specific to tactical planning. This provided the justification to support our argument about generality of the model. A linear programming formulation is provided to approximate the mixed integer formulation proposed so as to overcome the problem's combinatorial complexity. The potential capability of the linear approximation proposed also is demonstrated via a small set of test problems.     

Evaluation of the Alphasense optical particle counter (OPC-N2) and the Grimm portable aerosol spectrometer (PAS-1.108)

We compared the performance of a low-cost (～$500), compact optical particle counter (OPC, OPC-N2, Alphasense) to another OPC (PAS-1.108, Grimm Technologies) and reference instruments. We measured the detection efficiency of the OPCs by size from 0.5 to 5 µm for monodispersed, polystyrene latex (PSL) spheres. We then compared number and mass concentrations measured with the OPCs to those measured with reference instruments for three aerosols: salt, welding fume, and Arizona road dust. The OPC-N2 detection efficiency was similar to the PAS-1.108 for particles larger than 0.8 µm (minimum of 79% at 1 µm and maximum of 101% at 3 µm). For 0.5-µm particles, the detection efficiency of the OPC-N2 was underestimated at 78%, whereas PAS-1.108 overestimated concentrations by 183%. The mass concentrations from the OPCs were linear (r ≥ 0.97) with those from the reference instruments for all aerosols, although the slope and intercept were different. The mass concentrations were overestimated for dust (OPC-N2, slope = 1.6; PAS-1.108, slope = 2.7) and underestimated for welding fume (OPC-N2, slope = 0.05; PAS-1.108, slope = 0.4). The coefficient of variation (CV, precision) for OPC-N2 for all experiments was between 4.2% and 16%. These findings suggest that, given site-specific calibrations, the OPC-N2 can provide number and mass concentrations similar to the PAS-1.108 for particles larger than 1 µm.

Copyright © 2016 American Association for Aerosol Research     

厌氧氨氧化工艺处理煤化工焦化废水研究综述

煤化工行业迅速发展过程中产生大量难以降解的焦化废水。厌氧氨氧化(Anammox)凭借能耗低、无需投加碳源、污泥产量低和温室气体排放量少等优点,在焦化废水处理领域具有广阔的应用前景。为探究Anammox处理焦化废水时的理化反应,并给出提高处理效率的解决办法,运用引文分析软件VOSviewer对Anammox处理焦化废水的研究进展进行文献计量学分析,梳理Anammox处理焦化废水时受到的影响因素,阐述Anammox的优势、机制与经济分析,总结Anammox应用难点并提出解决方案,以期为Anammox应用于煤化工废水处理提供参考。     

基于电压电流双环控制的蓄电池并网研究

针对常规蓄电池放电采用可变电阻器进行性能测试所引起的准确度低、可靠性差、操作困难等问题,文中提出了一种并网充放电的电池性能检测方式。通过对铅酸蓄电池中电荷量、温度、电流微分表达式的分析,建立由主反应支路和寄生支路组成的三阶等效数学模型。电池的充放电采用阶跃信号触发Buck-Boost双向变换电路开关通断的恒流模式。逆变电路采用电压电流双闭环控制,并经电感滤波后并入模拟电网。在MATLAB/Simulink软件上搭建的仿真模型验证结果表明蓄电池各项性能指标和并网电流动态响应良好,证明了文中所提方法的有效性和环保性。     

基于对巯基苯胺膜的高灵敏己烯雌酚印迹传感器的制备及应用

通过自组装技术,分别以金硫键（Au—S）和氢键在羧基化多壁碳纳米管（CMWCNTs）和纳米金（AuNPs）修饰的电极表面成功组装功能单体对巯基苯胺（p-ATP）和模板分子己烯雌酚（DES）,在含有p-ATP、DES、氯金酸和电聚合介质四丁基高氯酸铵的聚合液中采用电聚合的方法在组装电极表面形成聚合物膜,并用50%乙醇-0.1mol/L硫酸水溶液（1∶1,体积比）洗脱模板分子,成功制备了用于检测己烯雌酚的分子印迹电化学传感器。采用循环伏安法和差分脉冲伏安法研究印迹传感器的印迹效果和分析性能,并将该传感器应用于食品中己烯雌酚的快速检测。在最佳条件下,己烯雌酚的线性范围为1.0×10^-9～1.0×10^-5mol/L,检出限为3.3×10^-10mol/L,样品加标平均回收率为83.46%～98.21%,相对标准偏差（RSD）在1.01%～3.74%之间（n=5）。该传感器操作简单、检测快速灵敏、成本低、抗干扰能力强、稳定性好,有重要的应用价值。     

五味子蜂花粉不同萃取物对小鼠肝脏脂质过氧化及DNA氧化损伤的作用

五味子蜂花粉具有强抗氧化活性,为了探究其抗氧化活性成分分布,本研究采用体积分数75%乙醇溶液对五味子蜂花粉进行浸提,分别用石油醚、乙酸乙酯和正丁醇进行萃取,测定不同萃取物的活性成分和体外抗氧化活性,研究其对小鼠肝脏脂质过氧化的抑制作用和对·OH诱导的pBR322质粒DNA氧化损伤的保护作用。结果表明,五味子蜂花粉不同萃取物抗氧化活性及其对小鼠肝脏脂质过氧化的抑制作用和对DNA氧化损伤的保护作用均存在显著差异（P＜0.05）,其顺序为：正丁醇萃取物＞乙酸乙酯萃取物＞石油醚萃取物。正丁醇萃取物的总酚含量最高,为26.11 g/100 g,总黄酮含量为27.90 g/100 g;有很强的Fe2＋络合能力、还原力和对1,1-二苯基-2-三硝基苯肼自由基的清除能力;0.2 mg/mL正丁醇萃取物对小鼠肝脏脂质过氧化的抑制率可达85%以上。本研究为进一步分离纯化五味子蜂花粉高抗氧化活性酚类物质提供依据,同时为抗氧化功能食品的开发提供参考。