Dielectric properties of Li2O-3B2O3 glasses

The frequency and temperature dependence of the dielectric constant and the electrical conductivity of the transparent glasses in the composition Li2O-3B2O3 (LBO) were investigated in the 100 Hz- 10 MHz frequency range. The dielectric constant and the loss in the low frequency regime were electrode material dependent. Dielectric and electrical relaxations were respectively analyzed using the Cole-Cole and electric modulus formalisms. The dielectric relaxation mechanism was discussed in the framework of electrode and charge carrier (hopping of the ions) related polarization using generalized Cole-Cole expression. The frequency dependent electrical conductivity was rationalized using Jonscher's power law. The activation energy associated with the dc conductivity was 0.80 \pm 0.02 eV, which was ascribed to the motion of Li+ ions in the glass matrix. The activation energy associated with dielectric relaxation was almost equal to that of the dc conductivity, indicating that the same species took part in both the processes. Temperature dependent behavior of the frequency exponent (n) suggested that the correlated barrier hopping model was the most apposite to rationalize the electrical transport phenomenon in Li2O-3B2O3 glasses. These glasses on heating at 933 K/10h resulted in the known non-linear optical phase LiB3O5.Comment: 32 pages, 13 figure

Optimal Trajectory Planning for the Design Optimization of the Robotic Arm

This paper presents a synthetical approach for the design optimization and the trajectory of the robotic arm, angular velocity and acceleration of the robotic arm. The optimization of the robotic arm trajectory is a frequent design problem. Because of the complexity of this task in the past, many of the proposed approaches entailed only a suboptimal solution. The main problem in trajectory generation and tracking of robotic arm motions is to plan the trajectory and compute the required joint angles. Inverse kinematics modeling is usually adopted, though sometimes other approaches are needed due to the lack of reliability and accuracy of analytical methods. Due to that reason, previously, several authors have used evolutionary algorithms. Rana and Zalzala (1997) applied EA to the collision-free path planning of the robotic arm. In Garg & Kumar (2002), the formulation and application of Genetic Algorithm and Simulated Annealing for the determination of an optimal trajectory of a multiple robotic configuration is presented

Study and Analysis of Design Optimization and Synthesis of Robotic ARM

A robot is a mechanical or virtual artificial agent, usually an electro-mechanical machine that is guided by a computer program or electronic circuitry. Robots can be autonomous or semi-autonomous. In this thesis, design optimization strategies and synthesis for robotic arm are studied. In the design process, novel optimization methods have been developed to reduce the mass of the whole robotic arm. The optimization of the robotic arm is conducted at three different levels, with the main objective to minimize the robot mass. At the first level, only the drive-train of the robotic arm is optimized. The design process of a robotic arm is decomposed into selection of components for the drive-train to reduce the weight At the second level, kinematic data is combined with the drive-train in the optimization. For this purpose, a dynamic model of the robot is required. Constraints are formulated on the motors, gearboxes and kinematic performance At the third level, a systematic optimization approach is developed, which contains design variables of structural dimensions, geometric dimensions and drive-train composes. Constraints are formulated on the stiffness and deformation. The stiffness and deformation of the arm are calculated through FEA simulation. The main objective of the thesis is to design optimization and synthesis analysis of robotic arm. The corresponding deflections, stresses and strains for that load will be find out by suing the method of finite element analysis

Alcohol use and alcohol-use disorders among older adults in India: a literature review.

OBJECTIVES: With changing attitudes to alcohol and an increasing life span in India, the prevalence of alcohol use and misuse in successive cohorts of older people is likely to increase. In this paper, we attempt to review the most recent evidence covering alcohol use and alcohol-use disorders in the Indian elderly. METHODS: PubMed, PsycINFO and Indmed databases were searched using relevant keywords. Papers meeting eligibility criteria were selected through a sequential process of screening title, abstract and full text. Data were extracted into Excel sheets. RESULTS: There was a dearth of pan-national studies. There were several methodological issues with many studies especially related to measurement. A substantial proportion of individuals above the age of 50 years are current consumers of alcohol and the prevalence is generally higher in urban compared to rural areas. Older women are generally likely to be alcohol abstainers. The general trend appears to be a reduction in current drinking among successive age cohorts over the age of 50. Alcohol consumption in the older adults is associated with educational status, health status, chronic morbidity, employment status, socioeconomic status, auditory/locomotor impairment and asthma. CONCLUSION: Alcohol use and misuse is a problem among the Indian older adults. With socio-demographic changes that will further increase longevity, this problem is likely to increase and policy-makers need to plan for it. Future research needs to improve validity and reliability in study methodology, as well as add to the current evidence base

The glass transition and crystallization kinetic studies on BaNaB9O15 glasses

Transparent glasses of BaNaB9O15 (BNBO) were fabricated via the conventional melt-quenching technique. The amorphous and the glassy nature of the as-quenched samples were respectively, confirmed by X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC). The glass transition and crystallization parameters were evaluated under non-isothermal conditions using DSC. The correlation between the heating rate dependent glass transition and the crystallization temperatures was discussed and deduced the Kauzmann temperature for BNBO glass-plates and powdered samples. The values of the Kauzmann temperature for the plates and powdered samples were 776 K and 768 K, respectively. Approximation-free method was used to evaluate the crystallization kinetic parameters for the BNBO glass samples. The effect of the sample thickness on the crystallization kinetics of BNBO glasses was also investigated.Comment: 23 pages, 12 figure