Mode-I Fracture Toughness Analysis of n-HAPs Filled Dental Restorative Composites

Silicon - Fracture toughness of dental restoratives is of greater relevance, especially in stress relevance applications, i.e., resistance to crack propagation. This work aims to determine the mode...     

Investigation on novel wideband fractal antenna design based on cylindrical shape dielectric resonator

This article explains a novel approach for achieving wideband characteristics in case of dielectric resonator antenna (DRA). Wideband characteristic has been realized by uniting the concept of vastu purusha mandala (VPM)‐based fractal geometry with dielectric resonator antenna. VPM is Hindu religion‐based fractal geometry, which provides the advantage of decrease in volume to surface area of the radiator. This concept is useful to enhance impedance bandwidth of proposed antenna. For the purpose of validation, prototype of proposed antenna design has been fabricated as well as tested. After experimental testing, it is confirmed that the proposed radiator functions over the frequency range 2.6‐4.34 GHz with a percentage bandwidth of 46.52%. The proposed radiating arrangement provides peak gain of 6.3 dBi and stable far‐field characteristics. All these features make it applicable for WiMAX application (3.3 GHz).     

An Investigation of Experimental Dental Restorative Composites Filled with Nano-Hydroxyapatite Treated with Different Silanes

Silicon - In the complex oral atmosphere, these materials undergo drastic variations in the elastic modulus and yield strength over the operation transition range. This research work aims to...     

Determinants of success for promoting solar energy in Rajasthan,India

Out of a total 1100 MW new project allocations, Rajasthan received the maximum share of 873 MW (i.e., 79.36% of all India allocations) through competitive bidding in the first phase of Jawaharlal Nehru National Solar Mission (JNNSM). Furthermore, 722 reputed companies have already registered their interest for setting up of solar power plants amounting to a total capacity of 16,900 MW in Rajasthan. This preference is often attributed to geographical and climatic advantage of Rajasthan. Yet it remains unclear why some other States with similar climatic and geographical factors are less favored by investors? Here we argue that the answer to this paradox lies in other determinants such as policy, infrastructure, facilitation and governance that make Rajasthan a lucrative investment opportunity. The fact that our argument is robust is also validated by other studies that indentify critical barriers which if removed may provide enabling environment to solar energy development in India. Accordingly, we present a practitioner perspective and review the initiatives responsible for accelerated development of solar energy in Rajasthan. We also envision the future course of actions for this promising solar hotspot in western India. Understanding early ground-level efforts for solar energy development in Thar desert of Rajasthan may prove valuable for other regions in India and elsewhere.     

Tribological and Microstructure Behavior of Quicklime (CaO) Filled Silicon Bronze Alloy for Bearing Material

CaO filled silicon bronze (SiBr) alloy composites have been fabricated by a high temperature vacuum casting technique at five different weight percentages (0 wt%, 2.5 wt%, 5 wt%, 7.5 wt% and 10 wt% of CaO). The void contents, hardness and wear behavior of the CaO filled SiBr alloy composites were studied showing that the addition of particulates in base alloy reduces the void contents from 0.827 % to 0.504 % for 0 wt% to 7.5 wt% of CaO respectively. Similarly, the hardness of CaO filled SiBr alloy composites initially increases from 119.25 Hv to 140.8 Hv on addition of 7.5 % CaO but on further increase in filler content (10 wt%) the hardness decreases to 114.5 HV respectively. The specific wear rate of composite materials for applied load and sliding velocity factors showed surpassing behavior compared to unfilled alloy composites. To get the optimum response of wear behavior of composite materials the Taguchi L₂₅ orthogonal array was applied and the result shows the higher S/N ratio i.e. 106.33 dB. The analysis of variance (ANOVA) result shows that the filler content plays a major effect compared to other factors. The particulate filled composites were examined through scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDAX) and atomic force microscopy (AFM) in order to understand the wear mechanism and morphology behavior of the composites.     

The relationship between changes in equipment technology and wages in the US construction industry

The US construction industry has witnessed a drop in real wages since 1970. The decline in real wages may be attributed to a combination of socio‐economic factors like migrant labourers, fringe benefits, safety procedures, union membership and worker skills. Another factor that may be impacting construction real wages is technological changes over the past couple of decades, including technological changes in construction equipment. This paper examines the relationship between changes in equipment technology and changes in construction wages with the help of five factors of equipment technology change: control, energy, ergonomics, functionality and information processing. Furthermore, data from the US Bureau of Labor Statistics' Current Population Survey is used to examine the effects of computer usage on wages among US hourly workers in construction. The research findings show significant relations exist between changes in equipment control, functionality and information processing with wages among non‐supervisory workers. Another finding indicated that although non‐supervisory construction workers who use computers at work earn higher hourly wages, there was no added wage benefit after controlling for the effects of experience, education and age.     

Reduction of Mutual Coupling in Metamaterial Based Microstrip Antennas: The Progress in Last Decade

Compact multiple antennas are attracting much attention because of the rapid growth of the wireless multiple input multiple output communication systems. An important challenge in multiple antenna system is mutual coupling effects. A brief review of reduction of mutual coupling in antenna arrays by using metamaterial is presented. Different types of metamaterial structures like electromagnetic band gap substrate, defected ground structure, split ring resonator, complimentary split ring resonator, soft surfaces/high impedance surface and mender line structure are described along with their operational principles. Whereas the problems associated along with the comparison and comments on their scope of applications are analyzed.     

Dielectric resonator based two‐port dual band antenna for MIMO applications

This article investigates a dual band multiple input multiple output (MIMO) cylindrical dielectric resonator antenna (cDRA) for WLAN and WiMAX applications. It consists of two symmetrical orthogonally placed radiators. Each radiator is excited through a narrow rectangular aperture with the help of a microstrip line. For higher mode excitation, the proposed structure uses dual segment DRA which apparently looks like stacked geometry. The aperture fed dielectric resonator works as a feed for upper cDRA to generate higher order mode. The presented radiator covers the band between 3.3‐3.8 GHz and 5‐5.7 GHz. The measured isolation is better than 20 dB in the desired band. The average gain and radiation efficiency achieved for the proposed antenna is 6.0 dBi and 85%, respectively at the operating frequency band. In the proposed geometry, broadside radiation patterns are achieved by exciting HEM_11δ and HEM_12δ modes in a stacked geometry. Different MIMO performance parameters (ECC, DG, MEG, and CCL) are also estimated and analyzed. The prototype of proposed antenna is fabricated and tested. The measured outcomes are in good accord with the simulated one.     

A dual‐band circularly polarized antenna with aid of dual cylindrical dielectric resonator blocks

In this communication, a dielectric resonator based circularly polarized antenna is designed and investigated. A modified aperture is used to excite dual cylindrical dielectric resonator (CDR) blocks. Two important characteristics of the proposed radiator that makes it all the more attractive are as follows: (i) excitation of dual radiating modes that is, HEM_11δ and TE_01δ mode in cylindrical DR along with the support of dual‐band circularly polarized (CP) waves; (ii) arrangements of dual CDR blocks to reduce the Q‐factor which is useful to enhance the impedance bandwidth of both frequency bands. Fabrication as well as experimental measurement of the antenna prototype has been done for verifying simulation outcomes. This antenna design operates over dual frequency bands, that is, 5.01‐6.41 GHz and 7.3‐7.9 GHz with the fractional bandwidth of 24.73% and 9.39%, respectively. It supports CP waves over the frequency range 6.1‐6.5 GHz and 7.4‐7.8 GHz. The proposed antenna backs right‐hand circularly polarized (RHCP) radiation with an average gain of 4.5 dBi. These characteristics make it well fitted for WLAN, WiMAX (5.2/5.5/5.8 GHz), and downlink defense purpose satellite communication (7.2‐7.7 GHz).