Investigation on mechanical properties of woven alovera/sisal/kenaf fibres and their hybrid composites

The go-green concept results in multipoint focus towards materials made from nature; easily decomposable and recyclable polymeric materials and their composites along with natural fibres ignited the manufacturing sectors to go for higher altitudes in engineering industries. This is due to the health hazard and environmental problems faced in manufacturing and disposal of synthetic fibres. This study was undertaken to analyse the suitability of new natural fibre as an alternative reinforcement for composite materials. In this paper, tensile, flexural and impact test is made for the woven alovera and kenaf (AK), sisal and kenaf (SK), alovera, sisal and kenaf fibre hybrid epoxy composites (ASK). The composite laminates are made through a hand-layup process. The surface analysis is studied through scanning electron microscopy. From the investigation the SK hybrid composite shows good tensile property, AK hybrid composite shows better flexural property and the best impact strength is observed for ASK hybrid composite. The natural fibres slowly replace the synthetic fibres from its environmental impact, marching towards a revolution in engineering materials.     

Deep learning-based sign language recognition system for static signs

Neural Computing and Applications - Sign language for communication is efficacious for humans, and vital research is in progress in computer vision systems. The earliest work in Indian Sign...     

Letter to the editor: Design of FIR notch filters by using Bernstein polynomials

In this paper, Bernstein polynomials have been used to derive an explicit formula for the coefficients of linear phase FIR notch filters which are maximally flat at ω=0 and π. The approach is relatively simple and enables us to design the filter for a specific notch frequency and bandwidth. © 1997 by John Wiley & Sons, Ltd.     

SEASONAL VARIATIONS IN FATTY ACID COMPOSITION OF OIL IN DEVELOPING COCONUT

ABSTRACT

Studies on seasonal variation in oil and fatty acid profile of developing solid endosperm of two cultivars, West Coast Tall (WCT) and Chowghat Orange Dwarf (COD), and their hybrids indicated that oil percentage increased from 30% in 6‐month‐old nuts to 63% in matured nuts (12 months old). Nuts sampled during July from different levels of maturity had high oil percentage and followed by those sampled during April, October and January. During nut development to maturity, the percentages and contents of medium and long chain saturated fatty acids increased except that of palmitic and myristic acids. Concentration of long chain unsaturated fatty acids (LCUFAs) in developing coconut kernel were high at 5 and 6 months after fertilization and then decreased toward maturity. The LCUFAs were high in nuts developing during October; consequently, saturated to unsaturated fatty acid ratios were low during October. Results indicated that nuts matured during October had better nutritional quality for human consumption and those matured during January are more suitable for industrial purpose due to higher medium chain fatty acid concentrations.

PRACTICAL APPLICATIONS

Coconut is consumed either as the tender nut (5–6 months after fertilization) or as the kernel from mature nut (12 months after fertilization). Recent technologies of making snowball tender nut use the nuts aged 7–8 months old. Kernel also is consumed in this product. Apart from this, the coconut is being increasingly used for making different kernel‐based value‐added products. This information is useful, as the value‐added products are being developed using different maturities of coconut. Hence, it is of paramount importance that the fatty acid profile of coconut kernel is known in detail for assessing the safety of food consumption from the human health point of view. Apart from this, information on the seasonal variation in fatty acid profile of developing endosperm gives an integrated knowledge so as to optimize the usage of coconut kernel for both human consumption and industrial exploitation.

     

The textural properties of soy paneer

Toned dairy milk and soy milk were mixed in different proportions and coagulated at various temperatures to produce paneer blends, and their textural properties were evaluated. As the soy milk proportion in the blend increased from 0% to 50%, hardness, cohesiveness and chewiness of the samples decreased initially, but further increase in the blend from 50% to 100% cause these values to increase slightly. The proportion of soymilk in the prepared paneer had a significant effect on hardness, cohesiveness, adhesiveness, chewiness and yield, whereas the coagulation temperature affected cohesiveness and yield. The process parameters did not show any effect on the springiness.     

Decentralized linear quadratic power system stabilizers for multi-machine power systems

Linear quadratic stabilizers are well-known for their superior control capabilities when compared to the conventional lead?Clag power system stabilizers. However, they have not seen much of practical importance as the state variables are generally not measurable; especially the generator rotor angle measurement is not available in most of the power plants. Full state feedback controllers require feedback of other machine states in a multi-machine power system and necessitate block diagonal structure constraints for decentralized implementation. This paper investigates the design of Linear Quadratic Power System Stabilizers using a recently proposed modified Heffron?CPhillip??s model. This model is derived by taking the secondary bus voltage of the step-up transformer as reference instead of the infinite bus. The state variables of this model can be obtained by local measurements. This model allows a coordinated linear quadratic control design in multi machine systems. The performance of the proposed controller has been evaluated on two widely used multi-machine power systems, 4 generator 10 bus and 10 generator 39 bus systems. It has been observed that the performance of the proposed controller is superior to that of the conventional Power System Stabilizers (PSS) over a wide range of operating and system conditions.     

Analysis of electrical explosion of wire systems for the production of nanopowder

Nanoscience and nanotechnology continue to grow as fields of scientific research and commercial development as many fundamental properties are size dependent on the nano scale. There are so many techniques for the production and characterization of various ultra fine powders. To gain a fundamental understanding of size dependant properties of matter in the nanometer size regimes and to develop nanoscale materials into useful devices to benefit society requires detailed study of the experimental methods, better methods of sample preparation of mono dispersed material in large quantities, and development of nanoparticles characterization methods. Exploding wire method is one such method for the production of metal and metal oxide nanoparticles capable of producing bulk amount of metal nanoparticles at low cost. With the intention of developing better exploding wire system for the production of nanoparticle and to understand the nanoparticle formation process, we have developed two systems in the way of optimization of the experimental set-up for final production of nanoparticles. The detail analysis of the systems and its effect on the nanoparticles has been described in the paper.     

Protective effect of aqueous suspension of dried latex of <i>Calotropis procera</i> against oxidative stress and renal damage in diabetic rats

Calotropis species have been used in the traditional medicinal system for the treatment of diseases of the liver and abdomen. In view of the antioxidant and anti-hyperglycemic properties of an aqueous suspension obtained from the dried latex of Calotropis procera, the present study was carried out to evaluate its efficacy in affording protection against alloxan induced changes in rat kidney. A single intraperitoneal injection of alloxan (150 mg/kg) in rats produced hyperglycemia within 3 days and altered kidney functions over a period of 90 days. Daily oral administration of the aqueous suspension (100 and 400 mg/kg) in diabetic rats produced anti-hyperglycemic effect that was comparable to that of glibenclamide (10 mg/kg). Unlike glibenclamide, the aqueous suspension did not increase the serum insulin levels in diabetic rats. However, it produced a marked reduction in the levels of urinary glucose and protein and normalized the renal tissue levels of thiobarbituric acid-reactive substances (TBARS) and glutathione (GSH) in diabetic rats and the effect was comparable to that of glibenclamide. The protection afforded by the aqueous suspension was also evident from the histological analysis of the renal tissue. Our study shows that by exhibiting antioxidant and anti-hyperglycemic property the aqueous suspension of dried latex of C. procera affords protection against the complications associated with diabetes.     

Experimental Study of Parameters of a Plasma Antenna

A plasma column excited by a surface wave can act as a plasma antenna. Experiments are carried out to study the current and conductivity distributions, field, power patterns, directivity and efficiency of such a plasma antenna. In addition, an equivalent metallic copper antenna is built up and its antenna parameters are compared with that of the plasma antenna. Our findings indicate that the power content in the harmonics of the plasma antenna is more prominent as compared to the copper antenna (which only generates a fundamental frequency). However, the power patterns for both antennae are quite similar. To provide a more qualitative understanding regarding the generation of harmonics in the field of the plasma antenna, a bi-spectral analysis is performed to study the nonlinear interactions in the current fluctuations. Some specific features of the plasma antenna are investigated in our study, which may enhance the application prospect of the plasma antenna with respect to the conventional metallic antenna.     

Dynamic contribution of variable-speed wind energy conversion system in system frequency regulation

Frequency regulation in a generation mix having large wind power penetration is a critical issue, as wind units isolate from the grid during disturbances with advanced power electronics controllers and reduce equivalent system inertia. Thus, it is important that wind turbines also contribute to system frequency control. This paper examines the dynamic contribution of doubly fed induction generator (DFIG)-based wind turbine in system frequency regulation. The modified inertial support scheme is proposed which helps the DFIG to provide the short term transient active power support to the grid during transients and arrests the fall in frequency. The frequency deviation is considered by the controller to provide the inertial control. An additional reference power output is used which helps the DFIG to release kinetic energy stored in rotating masses of the turbine. The optimal speed control parameters have been used for the DFIG to increases its participation in frequency control. The simulations carried out in a two-area interconnected power system demonstrate the contribution of the DFIG in load frequency control.