Structural,Conductivity, and Dielectric Relaxation Studies of La0.9Ba0.1GaO3-δ System

La_0.9Ba_0.1GaO_3-δ has been synthesized through solid-state reaction method. X-ray diffraction, AC conductivity, and scanning electron microscopy are used to investigate the structural properties and morphology of the system. X-ray refinement indicates that LaGaO₃ is the major phase having an orthorhombic structure with the space group Ibmm. The study revealed that the Ba-dopant in the LaGaO₃ creates oxygen vacancies, which are responsible to increase the ionic conductivity through hopping mechanism. The activation energy of the system is nearly ～0.65 eV. It indicates that the major contribution to overall conductivity is ionic in the present system. The impedance behavior of the sample with frequency and temperature has been investigated using the Bode's plots. The loss tangent variation with temperature has been plotted to verify the relaxation behavior of the present system.     

A Comprehensive Structural Analysis Process for Failure Assessment in Aircraft Lap-Joint Mimics Using Intramodal Fusion of Eddy Current Data

In the aerospace industry, nondestructive evaluation (NDE) techniques are commonly used for structural health monitoring, including finding manufacturing and service-induced discontinuities and defects such as corrosion and cracks. A comprehensive structural analysis process is presented for quantizing and evaluating characteristics of aircraft lap-joint mimics. The process investigated here consists of NDE data acquisition, defect detection and characterization involving material loss estimation, three-dimensional structural model generation, finite-element modeling to simulate fatigue damage and comparison with actual tensile fatigue-induced structural analysis data (mechanical loading). The structural analysis process is examined using five test panels consisting of stacked and riveted aluminum plates, configured as lap-joints, four of them with different corroded patches at different layers of the lap-joints and one painted pristine panel used as a reference. The test panels were subjected to three rounds of incremental and cyclical tensile fatiguing with the final round resulting in complete fatigue failure. Eddy current data was obtained from the test panels prior to each round of mechanical loading. Comparing the simulated fatigue loading and the mechanical loading results for identifying susceptible-to-failure areas on the test panels, this comprehensive structural analysis process found the correct location of failure areas at rates as high as 88.9%.     

On process–structure–property interconnection in anti-phase synchronised twin-wire GMAW of low carbon steel

The paper investigates process–structure–property interconnection in anti-phase synchronised twin-wire gas metal arc welded low carbon steel samples wherein process variation is achieved by using similar and dissimilar currents and diameters at lead and trail wires. Scanning electron microscopy and microhardness measurements are used as characterisation techniques. The investigation offers new observations on heat generation and distribution in twin-wire welding that affect weld bead and microstructure formation due to changes in arc phenomenon and molten metal flow in weld pool. Use of dissimilar currents facilitates effective utilisation of heat. The two-stage arcing in twin-wire welding facilitates slow heating and cooling that leads to weld metal and heat affected zone softening. A combination of polygonal ferrite, pearlite and bainite with varying compositions is observed across the weldment. A higher current value and larger wire diameter at the lead wire leads to coarsening of the grains thereby reducing the hardness.     

Impact of Mutual Coupling on Adaptive Switching Between MIMO Transmission Strategies and Antenna Configurations

Adaptive switching between multiple-input multiple-output (MIMO) transmission strategies like diversity and spatial multiplexing is a flexible approach to respond to channel variations. It is desirable to obtain accurate estimates of the switching points between these transmission schemes to realize the capacity gains made possible by adaptive switching. In this paper, it is shown that the accuracy of switching point estimates for switching between statistical beamforming and spatial multiplexing is improved by taking into account the effects of mutual coupling between antenna array elements. The impact of mutual coupling on the ergodic capacities of these two transmission strategies is analyzed, by deriving expressions for the same. Adaptive switching between combinations of transmission strategies and antenna array configurations (using reconfigurable antenna arrays) is shown to produce maximum capacity gains. Expressions for the switching points between transmission strategies and/or antenna configurations, including mutual coupling effects, are derived and used to explore the influence of mutual coupling on the estimates. Finally, measurements taken from reconfigurable rectangular patch antenna arrays are used to validate the analytical results.     

Thirty years of a ban on the sale of noniodized salt: impact on iodine nutrition in children in Himachal Pradesh, India

BACKGROUND: A survey conducted by the central iodine-deficiency disorders team in Himachal Pradesh, a state in the goiter-endemic belt of India, revealed that 10 of its 12 districts have an endemic prevalence of goiter. The survey was conducted to provide health program managers data to determine whether it would be necessary to initiate intervention measures. OBJECTIVE: To assess the status of urinary iodine excretion and household salt iodization levels after three decades of a complete ban on the sale of noniodized salt in this goiter-endemic state in India as measured by assessment of urinary iodine excretion levels and iodine content of salt at the household level. METHODS: The guidelines recommended by WHO/ UNICEF/ICCIDD for a rapid assessment of salt iodization were adopted. In each of the 12 studied districts, all senior secondary schools were enlisted and one school was selected by using a random sampling procedure. Two hundred fifty children 11 to 18 years of age were included in the study. Urine samples were collected from a minimum of 170 children and analyzed using the wet digestion method. Salt samples were also collected from a minimum of 170 children and analyzed using the spot testing kit. RESULTS: All districts had a median urinary iodine excretion level > 200 microg/L and 82% of the families were consuming salt with an iodine content of 15 ppm or higher. CONCLUSIONS: The results of the present study high-light the successful implementation of the salt iodization program in the state of Himachal Pradesh. This positive impact may be due to the comprehensive strategy adopted by the state government to improve the quality of salt, development of an effective monitoring information system and effective information, education, and communication activities.     

3D Path Optimisation of Unmanned Aerial Vehicles Using Q Learning-Controlled GWO-AOA

Unmanned Aerial Vehicles (UAVs) or drones introduced for military applications are gaining popularity in several other fields as well such as security and surveillance, due to their ability to perform repetitive and tedious tasks in hazardous environments. Their increased demand created the requirement for enabling the UAVs to traverse independently through the Three Dimensional (3D) flight environment consisting of various obstacles which have been efficiently addressed by metaheuristics in past literature. However, not a single optimization algorithms can solve all kind of optimization problem effectively. Therefore, there is dire need to integrate metaheuristic for general acceptability. To address this issue, in this paper, a novel reinforcement learning controlled Grey Wolf Optimisation-Archimedes Optimisation Algorithm (QGA) has been exhaustively introduced and exhaustively validated firstly on 22 benchmark functions and then, utilized to obtain the optimum flyable path without collision for UAVs in three dimensional environment. The performance of the developed QGA has been compared against the various metaheuristics. The simulation experimental results reveal that the QGA algorithm acquire a feasible and effective flyable path more efficiently in complicated environment.     

Tailoring wind properties by various passive roughness elements in a boundary-layer wind tunnel

Bound-ary-layer wind tunnel provides a unique platform to reproduce urban, suburban and rural atmospheric boundary layer (ABL) by using roughness devices such as vortex generators, floor roughness, barrier walls, and slots in the extended test-section floor in the contraction cone. Each passive device impacts wind properties in a certain way. In this study, influence of various passive devices on wind properties has been investigated. Experiments using eighteen different configurations of the passive devices have been carried out to simulate urban, suburban, and rural climate conditions in a boundary-layer wind tunnel. The effect of each configuration on the wind characteristics is presented. It was found that higher barrier height and more number of roughness elements on the floor, generated higher turbulence and therefore higher model scale factors were obtained. However, increased slot width in the extended test-section floor in the contraction cone of the wind tunnel seemed to have a little effect on wind characteristics.     

Effect of Sr substitution on structural properties of LaCrO3 perovskite

Journal of Materials Science: Materials in Electronics - We present the structural studies of perovskite-type La1?xSrxCrO3 (0?≤?x?≤?0.30) compounds...     

探讨低成本GSM手机的解决之道

蜂窝手机市场日渐成熟,2005年销售量超过7.5亿部.整个手机市场可分为两类,一类是发达国家中购买升级换代手机的老用户,另一类是发达国家和发展中国家中购买第一部手机的新用户.升级换代的市场要求手机具有更多的新功能,包括增强的音频和视频功能,以便利用先进的空中接口,因为网络从GSM演变到GPRS、EDGE,一直到3G.这个市场还需要多模功能的手机——在一个手机中包括多种蜂窝通信标准或者集成不同的无线通信技术.……