Rubber–clay nanocomposite by solution blending

Ethylene vinyl acetate rubber (45% vinyl acetate content, EVA‐45) and organomodified clay (12Me‐MMT) composites were prepared by solution blending of the rubber and the clay. A combination of X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy studies showed that the composites obtained are on the nanometer scale. The measurements of the dynamic mechanical properties for different compositions over a temperature range (?100 to +100°C) showed that the storage moduli of these rubber–clay nanocomposites are higher above the glass to rubber transition temperature compared to the neat rubber. The tensile strength of the nanocomposites is about 1.6 times higher than that of the EVA‐45. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2216–2220, 2003     

Performance and emission characteristics of direct injection diesel engine using linseed oil as biodiesel by varying injection timing

The depletion of fossil fuels and increasing demand leads to research in alternate fuels. The alternate fuels are bio-degradable, renewable and non-toxic. Many types of oils are re-used in biodiesel production, considering their availability, among which linseed oil is the most significant one. Injection timing plays a major role among various injection parameters which affects its performance and emission characteristics. This paper focuses on experimental investigation on a single cylinder, four-stroke direct injection diesel engine with output of 5.2?kW at 1500?rpm at various injection timings, 20, 23, 26 degree BTDC for observing the performance and emission characteristics of direct injection diesel engine using methyl esters of linseed oil and its blends. The blends are B10, B20, and fuel characteristics are observed. The results show that when compared with diesel it gives an increase in BTHE and reduction in SFC. Both the biodiesel blends give lesser NOx. Slightly higher CO and HC emission were found. The performance and emissions were increased in when injection increased.     

Cryptographic pseudo-random sequences from the chaotic Hénon map

A scheme for pseudo-random binary sequence generation based on the two-dimensional discrete-time Hénon map is proposed. Properties of the proposed sequences pertaining to linear complexity, linear complexity profile, correlation and auto-correlation are investigated. All these properties of the sequences suggest a strong resemblance to random sequences. Results of statistical testing of the sequences are found encouraging. An estimate of the keyspace size is presented.     

Synthesis and characterization of indium intercalation compounds of tungsten disulphide: InxWS2 (0 ⩽ x ⩽ 1)

The present work reports on the synthesis of indium intercalation compounds In_xWS₂ (0 ? x ? 1). The material has been characterized by X-ray studies for structure determination and particle size distribution, room temperature magnetic susceptibility, thermoelectric power experiments and conductivity measurements in the temperature range 150–300 K. These results have indicated that, like the host material WS₂, the intercalated compounds also possess hexagonal symmetry and are diamagnetic p-type semiconductors. The activation energy for these compounds was determined from the conductivity data.     

Validating generality of recently developed critical plane model for fatigue life assessments using multiaxial test database on seventeen different materials

The present studies are aimed at validation of a newly developed critical plane model with respect to large variety of engineering materials used for different applications. This newly developed model has been recently reported by present authors. To strengthen general applicability of this model, multiaxial test database consisting of a wide variety of multiaxial loading paths have been considered. The strain paths include pure axial, pure torsion, in‐phase axial‐torsion, out‐of‐phase axial‐torsion with phase shift angles varying from 30° to 180° having sine/trapezoidal/triangular strain waveforms, with/without mean axial/shear strains and asynchronous axial‐torsion strain paths of different frequency ratios etc. The materials covered in present study are mainly categorized as ferrous and nonferrous alloys. In ferrous alloy category, material grades from plain carbon steel (mild steel, 16MnR, SA333 Gr. 6, E235 and E355), low‐alloy steel (1Cr‐Mo‐V and S460 N) and austenitic stainless steel (SS304, SS316L and SS347) have been considered. In nonferrous alloy category, aluminium alloys (2024T3‐Al, 7075T651‐Al, and PA38‐T6‐Al), titanium (pure titanium and TC4 alloy), cobalt base super‐alloy (Haynes 188), and nickel alloy (Inconel‐718) have been considered. The predicted and test fatigue lives are found in good agreement for all these materials and complex multiaxial loading paths.     

A central composite design based fuzzy logic for optimization of drilling parameters on natural fiber reinforced composite

Machining of polymeric composite is inevitable during assembly of components. In view of making holes on structural composites, drilling is essential and a study to optimize the machining parameters is very important. The present study has been made to investigate the defaces and cutting forces associated during drilling of natural fiber reinforced plastics. Plastic composite has been manufactured using chemically treated vetiveria zizanioides as the reinforcement and polyester as the matrix. The composite has been drilled several times on the basis of central composite design. Speed and feed rate of the spindle, point angle and diameter of the tool are considered as the input parameters. Deface of each hole during entry and exit, thrust force and torque have been measured as the output parameters. A fuzzy model has been created and a comparative study between the central composite design and fuzzy model is made. The design has been optimized with the objective of minimizing the output parameters and a set of confirmatory experiments have been conducted. The central composite model has been validated by comparing it with the fuzzy model and confirmatory runs. The comparison presented only a minimal error and hence the modeling by central composite design and fuzzy are consummate.     

Synthesis, magnetic properties and catalytic activity of hierarchical cobalt microflowers

A simple one pot synthesis method for the silver catalyzed growth of pure hexagonal close packed cobalt by the reduction of cobalt salt using hydrazine hydrate in the presence of triethanolamine (TEA), diethanolamine (DEA) and ethylene glycol (EG) as capping agents at 90 degrees C within 10 min has been reported. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of the product prepared in the presence of capping agents show the formation of the well defined porous flowery architecture originating from the interlinked 2D wavy nanoflakes. When the same reaction is performed in the absence of any capping agent, the agglomeration of the flakes of cobalt with irregular spherical morphology is observed. The effect of the reaction conditions on the size and the shape of the products have also been studied. Vibration sample magnetometer (VSM) shows, that the products are ferromagnetic in nature irrespective of the capping agents used and possess high value of coercivity, when prepared in the absence of any capping agent. These cobalt microflowers have also been proved as an alternative to the other available expensive catalysts (Au, Ag, Pt) in the room temperature production of p-aminophenol for its applications in pharmaceutical, photographic and plastic industries.     

Influence of uniaxial ratchetting on low cycle fatigue behviour of SA 333 Gr. 6 C–Mn steel

Ratchetting behaviour and its influence on the subsequent low cycle fatigue behaviour of a plain carbon steel (SA 333 Gr. 6) has been evaluated. Uniaxial stress controlled ratchetting experiments have been carried out at various combinations of mean stress and stress amplitudes. It is noted that the ratchetting strain increased with increasing mean stress and stress amplitude. Maximum strain accumulation was observed for the highest value of the peak stress, irrespective of the stress ratio. Further, post ratchetting-low cycle fatigue (LCF) tests have been carried out and compared with non-ratchetted base LCF behaviour. The comparison showed that the fatigue life decreased in proportion to the accumulated ratchetting strain. This indicates that accumulation of significant ratchetting strain can be detrimental to the fatigue life and must be avoided. Mean stress induced due to pre-ratchetting is found to be responsible for the decrease in LCF fatigue life.     

Sea urchin shaped ZnO coupled with MoS2 and polyaniline as highly efficient photocatalysts for organic pollutant decomposition and hydrogen evolution

In this work, an attempt has been made to fabricate multifunctional composite photocatalysts by coupling sea urchin shaped ZnO with MoS₂ and polyaniline (PANI) sheets, and a significant improvement in photocatalytic activity was perceived with composites in comparison to pristine components. It was found that the ternary ZnO–MoS₂-PANI photocatalyst showed excellent adsorptive decomposition of organic pollutants natural sunlight irradiation. In addition, enhanced photocatalytic hydrogen evolution was also evidenced, which revealed the multifunctional nature of the photocatalysts. In the case of organic pollutant decomposition, the presence of MoS₂ in ZnO–MoS₂-PANI offers abundant catalytic active sites which result in adsorption of the pollutants and boost the photocatalytic activity. While for the photocatalytic hydrogen evolution, the binary ZnO-PANI composite showed the utmost activity in comparison to the pristine components and ZnO–MoS₂-PANI, which is due to the fact that the higher loading of MoS₂ in the composite increases the number of S atoms on the basal planes, which are inactive for H₂ evolution, and hence results in decreased photocatalytic activity. The results discussed in this work may pave the approach for the design and development of ZnO based multifunctional materials for diverse photocatalytic applications.     

Three-phase two-way relaying with imperfect channel estimation and asymmetric traffic requirements: performance analysis and optimization

We study the effect of imperfect channel estimation (ICE) and asymmetric traffic requirements (ATRs) on the performance of bidirectional relaying with a direct link by employing three-phase analog network coding under Nakagami-m fading. Under such a realistic scenario, a tight lower bound on the overall outage probability is derived in closed-form, while a useful expression is presented for the asymptotically low outage regime. We also deduce the tight closed-form expression for the ergodic sum-rate. Furthermore, we formulate and solve analytically three optimization problems viz., relay power allocation under fixed location of the relay, relay position with fixed relay power allocation, and joint optimization of relay power allocation and location. Our results reveal that for given ICE, the optimal relay location offers significant system performance enhancement under ATRs, whilst the optimal relay power allocation has a more noticeable impact under symmetric traffic. It is also shown that the joint optimization of relay power allocation and location can further enhance the system performance, regardless of ATRs and ICE. Above all, based on the direct link quality, we show that the considered scheme outperforms its two-phase counterpart, even in the low signal-to-noise ratio regime.