A modified rain attenuation prediction model for tropical V‐band satellite earth link

Radio wave propagation plays a very important part in the design and eventually dictates performance of space communication systems. Over time, the requirements of satellite communication have grown extensively where higher capacity communications systems are needed. Escalating demands of microwave and millimetre wave communications are causing frequency spectrum congestion. Hence, existing and future satellite system operators are planning to employ frequency bands well above 10 GHz. The challenge in operating at such high frequencies for communication purposes is that there exists stronger electromagnetic interaction between the radio signals and atmospheric hydrometeors. Such instances will degrade the performance of such high frequency satellite communication systems. The development of a revised model for a better‐improved rain fade prediction of signal propagations in tropical region is considered very important. Researchers and engineers can employ the model to accurately plan the future high frequencies satellite services. Copyright © 2014 John Wiley & Sons, Ltd.     

Formulation of fumed silica grease from waste transformer oil as base oil

This study aimed to formulate fumed silica (FS) grease using waste transformer oil (WTO) and to investigate the grease properties. Various unexplored application of the reused WTO due to its reusable characteristic. WTO and fresh transformer oil (ITO) were used as grease base fluid and the properties of oil and grease were evaluated using ASTM International standards and SKF’s Grease Test Kit. The oil and grease chemical compound were determined using Fourier Transform-Infrared Spectroscopy at wavenumber of 500–4000?cm^?1. It was found that WTO have high viscosity index of 96 and low moisture content of 0.05% after pre-treatment than ITO. FS greases with and without MoS₂ were classified as NLGI 2 greases when FS content was 8%. Grease formulated with MoS₂ shows better performances in term of corrosiveness, oil bleed within ?15% to +15%, oil separation less than 4%, and dropping point of >300?°C. FTIR results shows no significant different between ITO and WTO, and between all formulated greases. Based on the findings, it was concluded that WTO can be utilized as an alternative base oil in grease formulation due to the good properties exhibited by the formulated WTO-based FS grease blended with MoS₂.     

Interference Aware Route Discovery in Wireless Mobile Ad Hoc Networks

In this paper, we propose an interference aware expanding region search algorithm to locate a destination in mobile ad hoc networks. In the proposed approach, signal to interference plus noise ration (SINR) is used in place of TTL field of a route request packet. The source node initializes the search query with a threshold value of SINR. Each relay node forwards the packet if its SINR satisfies the threshold criteria provided by the source node in RREQ packet. As a result, the low SINR nodes are removed in route discovery phase prior to the establishment of routes. The simulation results show that proposed algorithm provides significant improvement in performance of reactive routing protocol in terms of reduced routing overhead, reduced energy consumption, and increased network throughput.

     

The Nanometer-Sized Eutectic Structure of Si/CrSi<Subscript>2</Subscript> Thermoelectric Materials Fabricated by Rapid Solidification

Nanostructuring is known to be an effective method to improve thermoelectric performance but, generally, it requires complex procedures and much labor. In the present study, self-assembled nanometer-sized composite structures of silicon (Si) and chromium disilicide (CrSi₂) were easily fabricated by the rapid solidification of a melt with a eutectic composition. Ribbon-like samples were obtained with a dominant nanostructure of fine aligned lamellae with a spacing range of 20–35 nm. The thermoelectric power factor of the ribbon was observed to be 1.2 mW/mK² at room temperature and reached 3.0 mW/mK² at 773 K. The thermal conductivity was 65% lower than that of a bulk eutectic sample. The results suggest that this method is promising for fabricating an effective nanostructure for thermoelectric performance.     

Quantum‐Tunneling Metal‐Insulator‐Metal Diodes Made by Rapid Atmospheric Pressure Chemical Vapor Deposition

A quantum‐tunneling metal‐insulator‐metal (MIM) diode is fabricated by atmospheric pressure chemical vapor deposition (AP‐CVD) for the first time. This scalable method is used to produce MIM diodes with high‐quality, pinhole‐free Al₂O₃ films more rapidly than by conventional vacuum‐based approaches. This work demonstrates that clean room fabrication is not a prerequisite for quantum‐enabled devices. In fact, the MIM diodes fabricated by AP‐CVD show a lower effective barrier height (2.20 eV) at the electrode–insulator interface than those fabricated by conventional plasma‐enhanced atomic layer deposition (2.80 eV), resulting in a lower turn on voltage of 1.4 V, lower zero‐bias resistance, and better asymmetry of 107.     

A probabilistic home-based routing scheme for delay tolerant networks

Wireless Networks - In traditional Mobile Adhoc Networks routing algorithms, the existence of a sustainable path between the source and destination is a crucial issue. These algorithms are shown to...     

Design and Implementation of Optical Signal Reinstatement Technique for High DPSK RZ Transceiver Scheme

Wireless Personal Communications - Optical signal reinstatement (OSR) is a common technique used in high-speed communication systems. OSR can be achieved using various techniques such as;...     

A CMOS digitally programmable filter technique for VLSI applications

A novel technique for designing analog CMOS integrated filters is proposed. The technique uses digitally controlled current amplifiers (DCCAs) to provide precise frequency and/or gain characteristics that can be digitally tuned over a wide range. This paper provides an overview of the possibilities of using the DCCA as the core element in programmable filters. In mixed analog/digital systems, the digital tuning feature of the proposed approach allows direct interfacing with the digital signal processing (DSP) part. Basic building blocks such as digitally programmable amplifiers, integrators, and simulated active inductors are given. Systematic designs of second-order filters are presented. Fully differential architectures of the proposed circuits are developed. Experimental results obtained from 0.5 μm standard CMOS chips are provided.     

Targeted Delivery of Anesthetic Agents to Bone Tissues using Conductive Microneedles Enhanced Iontophoresis for Painless Dental Anesthesia

Pain management during dental procedures is a cornerstone for successful daily practice. In current practice, the traditional needle and syringe injection is used to administer local anesthesia. However, the appearance of long needles and the pain associated with it often leads to dental anxiety deterring timely interventions. Microneedles (MNs) have emerged as a minimally invasive alternative to hypodermic needles and shown to be effective in transdermal drug delivery applications. In this article, the potential use of MNs for local anesthesia delivery in dentistry is explored. The development of a novel conductive MN array that can be used in combination with iontophoresis technique to achieve drug penetration through the oral mucosa and the underlying bone tissue is presented. The conductive MN array plays a dual-role, creating micro-conduits and lowering the resistance of the oral mucosa. The reduced tissue resistance further enhances the application of a low-voltage current that is able to direct and accelerate the drug molecules to target the sensory nerves supplying teeth. The successful delivery of lidocaine using this new strategy in a clinically relevant rabbit incisor model is shown to be as effective as the current gold standard.