Mechanical performance of statically loaded flat face epoxy bonded concrete joints

One of the main challenges in the offshore renewable energy industry is the reduction in the levelised cost of energy of wind, wave and tidal devices. The use of concrete as the primary construction material in such devices presents a low unit cost, high marine durability alternative to steel, however, to maximise material efficiency factors such as mix constituent design, structural detailing and manufacturing processes have to take into account the specific conditions of the marine environment. Pre-cast segmental construction can be considered as one of the fastest and cheapest construction options. However the challenges regarding performance of epoxy bonded concrete in marine environment should be taken into account. This paper presents the results of an experimental programme on the performance of shear and tensile capacity of flat face concrete joints, focussing on the effect of substrate surface preparation, joint thickness, properties of epoxy resins, exposure to seawater and presence of joint defects on the ultimate failure load. The ultrasonic pulse velocity (UPV) method for detection of defects in the adhesive layer was examined and digital image correlation is used to observe the surface strain flow through the joint. The results indicate that the epoxy joints behave monolithically and remain undamaged under different types of static loading. The joints do not significantly interrupt the flow of strain but can locally affect the distribution of strain (and thus stiffness and stresses) in a structure. An increase in the density of the epoxy (and the filler content) leads to the increase in the joint strength and thicker joints are less affected by small defects in the bonding layer. The majority of tested specimens failed by cracking of concrete rather than by debonding of the joint, whilst compressive stresses acting on the joint can help to augment its shear strength. Sandblasting of bonded surfaces can improve performance of joints, whereas UPV testing may be used for quality control of epoxy-bonded joints

Fuzzy LPCM controlled buck integrated PFC convert-er for Class-C&D appliances

This propounded a novel method of design and implementation of a fuzzy linear peak current mode (LPCM) controlled Buck Integrated Power Factor Correction (PFC) Converter. It derives its advantages through low buck capacitor voltage and single control switch, which leads to reduced complex control and price. Sub-harmonic oscillations generates in peak current controller can be nullified by using ramp signal, there by improves the overall performance of the converter. The fuzzy controller (FLC) robust and effective than conventional linear controllers like P, PI, PID, hence in this work a (90 – 265V), 50Hz AC, 48V DC and 100 kHz frequency converter is implemented in MATLAB/Simulink software and results are verified experimentally. Results show that converter meets international regularity commission regulations.</jats:p

Enhanced electron emission from coated metal targets: Effect of surface thickness on performance

In this work, we establish an analytical formalism to address the temperature dependent electron emission from a metallic target with thin coating, operating at a finite temperature. Taking into account three dimensional parabolic energy dispersion for the target (base) material and suitable thickness dependent energy dispersion for the coating layer, Fermi Dirac statistics of electron energy distribution and Fowler’s mechanism of the electron emission, we discuss the dependence of the emission flux on the physical properties such as the Fermi level, work function, thickness of the coating material, and operating temperature. Our systematic estimation of how the thickness of coating affects the emission current demonstrates superior emission characteristics for thin coating layer at high temperature (above 1000 K), whereas in low temperature regime, a better response is expected from thicker coating layer. This underlying fundamental behavior appears to be essentially identical for all configurations when work function of the coating layer is lower than that of the bulk target work function. The analysis and predictions could be useful in designing new coated materials with suitable thickness for applications in the field of thin film devices and field emitters

IMPLEMENTATION OF LOAD FOLLOWING IN MULTI AREA HYDROTHERMAL SYSTEM UNDER RESTRUCTURED ENVIRONMENT

This paper presents the method in implementing the concept of load following adapted in an Automatic Generation Control (AGC) under restructured scenario. Open transmission access and the evolving of more socialized companies for generation, transmission and distribution affects the formulation of AGC problem. To accommodate new constraints associated with territorial of the traditional AGC two area system is modified to take into account the role of AGC in open market system. This paper investigates the performance of a load following controller on each generator involved in bilateral contracts. A suitable control strategy is also proposed for the generators taking part in load following to share a portion of the uncontracted power demanded by the customers. The concept of Disco Participation is employed and reflected in the two-area block diagram. The proposed system is tested for a two area hydrothermal system considering without and with contract violation. Simulation results show that the concept of load following is successfully implemented in the syste

Formulation and Invitro Evaluation of Immediate Release Tablets Containing Febuxostat

In the present research work, Febuxostat Immediate Release Tablet was prepared by direct compression method using varying concentrations of Lycoat, Crospovidone&amp; Croscarmellose sodium as disintegrants. The formulations prepared were evaluated for precompression&amp; post-compression parameters. From the drug excipient compatibility studies, we observe that there are no interactions between the pure drug (Febuxostat) and optimized formulation (Febuxostat+ excipients) which indicates there are no physical changes. Post compression parameters were found to be within the limits. Among the formulation prepared the tablet containing 12mg of CCS shows 98.13% of the drug release within 45 min &amp; follows first-order kinetics