Surface roughness and the sensitivity of D-shaped optical fibre sensors

In this paper, the surface roughness characteristic of D-shaped optical fibre sensors with its effects on the sensitivity has been studied. The ULTRAPOL end and edge polishing system was used with some modifications to fabricate the D-shaped sensors with planar sensing zone from the single-mode optical fibres. The mean surface roughness of 343, 96, 25 and 9?nm was estimated at the sensing zone of the D-shaped sensors which were sequentially polished with 30, 9, 3 and 0.5?µm grit size polishing films, respectively. From the experimental results, it has been observed that surface roughness of the sensing zone does not exhibit the significant effects on the output signal strength, whereas the sensitivity of the D-shaped sensors nonlinearly related with the surface roughness of the sensing zone. The designed D-shaped optical fibre sensors have potential applications in biomedical and chemical industries.     

Simulation,modeling and analysis of master node election algorithm based on signal strength for VANETs through Colored Petri nets

The broadcast storm problem causes redundancy, contention and collision of messages in a network, particularly in vehicular ad hoc networks (VANETs) where number of participants can grow arbitrarily. This paper presents a solution to this problem in which a node is designated as a master through an election process. Moreover, an algorithm is proposed for asynchronous VANETs to select a master node, where the participants (i.e., vehicles) can communicate with each other directly (single-hop). The proposed algorithm is extrema-finding in a way that a node having maximum signal strength is elected as a master node and each vehicle continues communication with the master until the master node keeps its signal strength at the highest level and remains operational too. This paper further presents the Petri net-based modeling of the proposed algorithm for evaluation which is going to be presented for the first time in leader election algorithm in VANETs. Verification of the proposed algorithm is carried out through state space analysis technique.

     

Hybrid Anomaly Detection by Using Clustering for Wireless Sensor Network

Wireless Personal Communications - Performance of wireless sensor network are highly prone to network anomalies particularly to misdirection attacks and blackhole attacks. Therefor intrusion...     

Single layer thin photoresist soft etch mask for MEMS applications

Microsystem Technologies - Substrate masking plays an important role in wet chemical etching process, however; coating a cost effective masking material with higher stability in the harsh chemical...     

TD-LTE抢占无线全新商机带动全球发展势态

1 前言 LTE是目前大部分电信运营商首选的下一代移动通信技术,全球已有100多家运营商承诺于2010年开始部署LTE。不过,在非成对频段上部署LTE的商机却常被忽略。     

Removal and recovery of uranium from aqueous solutions by Trichoderma harzianum

Removal and recovery of uranium from dilute aqueous solutions by indigenously isolated viable and non-viable fungus (Trichoderma harzianum) and algae (RD256, RD257) was studied by performing biosorption-desorption tests. Fungal strain was found comparatively better candidate for uranium biosorption than algae. The process was highly pH dependent. At optimized experimental parameters, the maximum uranium biosorption capacity of T. harzianum was 612 mg U g(-1) whereas maximum values of uranium biosorption capacity exhibited by algal strains (RD256 and RD257) were 354 and 408 mg U g(-1) and much higher in comparison with commercially available resins (Dowex-SBR-P and IRA-400). Uranium biosorption by algae followed Langmuir model while fungus exhibited a more complex multilayer phenomenon of biosorption and followed pseudo-second-order kinetics. Mass balance studies revealed that uranium recovery was 99.9%, for T. harzianum, and 97.1 and 95.3% for RD256 and RD257, respectively, by 0.1M Hydrochloric acid which regenerated the uranium-free cell biomass facilitating the sorption-desorption cycles for better economic feasibility.     

Microwave subsurface imaging of dielectric structures using fractal geometries of complementary split ring resonators

In this paper, newly proposed complementary split ring resonator (CSRR) structures of fractal geometries are used for microwave imaging of coated dielectric structures in order to detect concealed voids or similar inclusions. The proposed fractal‐based CSRR structures are found to display improved sensitivity as compared to the conventional square CSRR sensors of same cross‐sectional dimensions, and thus appear to be more appropriate for imaging applications. Detailed analyses of different orders of square Sierpinski fractals have been carried out. Raster scanning of the test region is performed and various parameters such as the magnitude and phase at unloaded resonant frequency, along with the shift in resonant frequency when loaded with the test structure are measured. Furthermore, both qualitative and quantitative images of the test structure are retrieved in terms of all the three measured parameters. Simulation and experimental results demonstrate the applicability of the proposed sensor for microwave imaging.     

Porous Strontium Chloride Scaffolded by Graphene Networks as Ammonia Carriers

Strontium chloride (SrCl₂) as ammonia (NH₃) carriers has been widely exploited due to its high ammonia uptake capacity and low energy penalty for ammonia release. However, the dramatic volume swing during absorption–desorption cycles, from SrCl₂ to Sr(NH₃)₈Cl₂ to SrCl₂, imposes a challenge to structure SrCl₂ for ammonia storage applications. Herein, a novel porous SrCl₂ structure with SrCl₂ loading up to 96 wt%, scaffolded by reduced graphene oxide (rGO) networks is reported. The optimized porous SrCl₂-rGO composite with 80 wt% SrCl₂ loading maintains the macro- and micro-structure accommodating the volume swing during ammonia absorption–desorption cycles without disintegration, whereas structured SrCl₂ pellets disintegrates directly after the first cycle of NH₃ absorption. The structured porous 80 wt% SrCl₂-rGO composite demonstrates rapid absorption–desorption kinetics, 140% faster in absorption and 540% faster in desorption compared with pure SrCl₂ pellet. The enhancement of the surface area and the presence of SrCl₂ particles in the pores of rGO networks result in a robust and stable structure offering rapid ammonia absorption–desorption kinetics while countermining the volume swing by self-adjusting “breathing.”