Design issues and performance analysis for DSR routing with reclaim‐based caching in MANETs

Mobile ad hoc networks (MANETs) have been positioned as one of the most important emerging wireless communication scenarios. Temporally formed by a collection of wireless mobile hosts, a MANET does not require the aid of any centralized administration. From this stems a suite of challenges in achieving an efficient MANET routing and content delivery in order to make the best use of precious resources and reduce the routing overhead at each MANET host. One of the reported approaches for solving the issue is the use of caching, which is expected to minimize the routing overhead by taking advantage of the limited memory at each mobile host. This paper introduces a novel scheme for addressing the above issue, called Reclaim‐Based Caching (RBC) policy, which dynamically utilizes a cache replacement mechanism of reclaiming stale routes to efficiently verify and validate a recoverable caching mechanism in Dynamic Source Routing. The main design purposes of RBC are to reduce the routing control overhead, lower the end‐to‐end routing delay, enhance the packet delivery ratio, and obtain a higher throughput for improving routing performance and accelerating the Route Discovery process due to low temporary link failure and high cache utilization. Hence, we can gather all feasible and historical route information into the cache library to be reclaimed as a threshold of efficient routing control. Consequently, the proposed RBC of this paper can be used in the universal wireless network environment to achieve better routing performance and to provide a more flexible real‐time application. Copyright © 2009 John Wiley & Sons, Ltd.     

Hide-n-Sense: Preserving Privacy Efficiently in Wireless mHealth

As healthcare in many countries faces an aging population and rising costs, mobile sensing technologies promise a new opportunity. Using mobile health (mHealth) sensing, which uses medical sensors to collect data about the patients, and mobile phones to act as a gateway between sensors and electronic health record systems, caregivers can continuously monitor the patients and deliver better care. Furthermore, individuals can become better engaged in monitoring and managing their own health. Although some work on mHealth sensing has addressed security, achieving strong privacy for low-power sensors remains a challenge. We make three contributions. First, we propose an mHealth sensing protocol that provides strong security and privacy properties at the link layer, with low energy overhead, suitable for low-power sensors. The protocol uses three novel techniques: adaptive security, to dynamically modify transmission overhead; MAC striping, to make forgery difficult even for small-sized Message Authentication Codes; and asymmetric resource requirements, in recognition of the limited resources in tiny mHealth sensors. Second, we demonstrate its feasibility by implementing a prototype on a Chronos wrist device, and evaluating it experimentally. Third, we provide a security, privacy, and energy analysis of our system.     

Aptamer‐Functionalized Multidimensional Conducting‐Polymer Nanoparticles for an Ultrasensitive and Selective Field‐Effect‐Transistor Endocrine‐Disruptor Sensors

An endocrine disruptor (ED) is a type of xenobiotic compound that can cause serious diseases related to the estrous cycle, as well as various types of cancer. At low ED concentrations, estrogen receptors may respond as they would under physiological conditions. In this work, aptamer‐functionalized multidimensional conducting‐polymer (3‐carboxylate polypyrrole) nanoparticles (A_M_CPPyNPs) are fabricated for use in an FET sensor to detect bisphenol A (BPA). The multidimensional system, M_CPPyNPs, is first produced by means of dual‐nozzle electrospray of pristine CPPyNPs and vapor deposition polymerization of additional conducting polymer. The M_CPPyNPs are then immobilized on an amine‐functionalized (–NH₂) interdigitated‐array electrode substrate, through the formation of covalent bonds with amide groups (–CONH). The amine‐functionalized BPA‐binding aptamer is then introduced in the same way as that for M_CPPyNP immobilization. The resulting A_M_CPPyNP‐based FET sensors exhibit ultrasensitivity and selectivity towards BPA at unprecedentedly low concentrations (1 fm ) and among molecules with similar structures. Additionally, due to the covalent bonding involved in the immobilization processes, a longer lifetime is expected for the FET sensor.     

RDX基发射药子弹撞击特性研究

为了研究含RDX基发射药的子弹撞击特性,利用弹道枪发射的12.7mm标准弹对某种典型RDX基发射药进行了子弹撞击试验研究,并与单基发射药的子弹撞击特性进行对比.结果表明:RDX基发射药子弹撞击反应剧烈程度和冲击波超压均高于单基发射药,其安全性低于单基发射药;大弧厚RDX基发射药试样反应剧烈程度明显低于小弧厚试样,冲击波...     

Improving the photovoltaic performance of co‐evaporated Cu2ZnSnS4 thin‐film solar cells by incorporation of sodium from NaF layers

We have investigated the influence of sodium (Na) on the properties of co‐evaporated Cu₂ZnSnS₄ (CZTS) layer microstructures and solar cells. The photovoltaic performance and diode properties were improved by incorporating Na from NaF layers into the CZTS layers, while Na had a negligible effect on the microstructural properties of the layer. The best cell fabricated by using an optimal CZTS layer (Cu/(Zn + Sn) = 0.70, Zn/Sn = 1.8) yielded an active area efficiency of 5.23%. The analysis of device properties suggests that charge‐carrier recombination at CZTS/CdS interface is suppressed by intentional Na incorporation from NaF layers. Copyright © 2016 John Wiley & Sons, Ltd.     

Characterization of polymer-adhesive interfaces on a nanometre scale by elemental mapping and image EELS using EFTEM

Energy-filtering transmission electron microscopy (EFTEM) was applied for investigating interfaces between a polymer and an adhesive. The sample employed in this work is polybutylene terephtharate (PBT) sheets laminated with an epoxy adhesive. It was found that heat aging of the PBT at 180 degrees C in air for > 9 h prior to adhesion decreases the adhesion strength drastically. To investigate this unfavourable aging effect on the adhesion strength, we performed elemental mapping and image EELS using EFTEM. A weak boundary layer with a thickness of < 50 nm was visualized at the PBT-adhesive interface by elemental mapping in the sample subjected to the heat aging and image EELS revealed the origin of this layer. Thus, we clearly correlated the nanoscale interfacial structure with the adhesion strength by EFTEM.     

Simulation and experimental study of chaos generation in microwave band using Colpitts circuit

Chaotic Colpitts circuits with fundamental frequency f^＊ beyond 1GHz are studied by both circuit simulation and experiment using Philips＇ broadband transistor with threshold frequency of 25GHz. For the basic configuration of Colpitts circuit with f^＊ of about 1,6GHz, broadband continuous power spectra could be obtained from both circuit simulations and experiments. The harmonics of the observed signal from Agilent PSA/ESA spectrum analyzer are as noticeable as far as 12GHz. A modified Colpitts circuit structure employing the parasitic inductance of BJT （Bipolar Junction Transistor） is also proposed and investigated. By circuit simulation, chaotic attractor and broadband continuous power spectra could be obtained from the modified Colpitts circuit with f^＊ of about 3.5GHz. Because the parasitic effects of the prototype board, the experiment result of the modified Colpitts circuit does not agree well with the simulation result. The gap between the simulation and experimental result could be bridged by replacing the lumped circuit elements with distributed ones.     

Group-Scheduling for Multi-Service Optical Burst Switching (OBS) Networks

We propose a new burst scheduling mechanism for Optical Burst-Switched (OBS) networks. The new approach is made possible by gathering data bursts into groups and performing the scheduling decision for each group collectively. In OBS group-scheduling, bursts will not be considered for scheduling until a pre-defined time period elapses, during which the group of burst header packets would be gathered. By transforming a set of data bursts into a set of corresponding time intervals, the problem of scheduling these bursts is transformed into a combinatorial optimization problem. Graph algorithms are applied to obtain the maximum number of non-overlapping bursts. The proposed OBS group-scheduling scheme is shown to improve the performance of OBS networks over existing scheduling schemes in terms of burst loss probability and channel utilization. With an extension through a sequential optimization, using a Branch-and-Bound technique, the proposed scheme can support multiple classes of service. It is shown that the new scheduling approach has several desired characteristics including fairness and service differentiability among classes in terms of burst loss probability and channel utilization.     

Development of intracranial brain-computer interface system using non-motor brain area for series of motor functions

An intracranial brain-computer interface (BCI) system using the neuronal activity of a non-motor brain area to fulfil a series of motor functions has been developed. The presented BCI system encodes a series of motor functions into a small number of neuronal units of the primary somatosensory cortex of a rat and generates real-time command signals to control a machine according to the animal's motor intentions. The results of this study demonstrate the practical usability of the BCI system using a non-motor brain area in the field of rehabilitation.     

Stator-flux-oriented control of induction motor considering ironloss

Research to consider the influences of iron loss has been made in the vector control of an induction motor. However, little work has been done in the area of a stator-flux-oriented control system of an induction motor. This paper investigates the effects of iron loss in the direct stator-flux-oriented control system of an induction motor, and proposes a control algorithm considering iron loss. The iron loss is modeled by equivalent iron loss resistance in parallel to the magnetizing inductance. Torque control capability is much improved and the speed estimation error for a speed-sensorless drive is reduced by the proposed control algorithm. The effectiveness of the proposed method is verified by simulation and experimental results