Investigation of Mechanical Properties and Dry Sliding Wear Behaviour of Squeeze Cast LM6 Aluminium Alloy Reinforced with Copper Coated Short Steel Fibers

LM6 aluminium alloy with 2.5–10 wt% of copper coated short steel fiber reinforced composites were prepared using squeeze casting process. Microstructure and mechanical properties viz., hardness, tensile strength and ductility were investigated. Dry sliding wear behaviour was tested by considering sliding distance and load. Fracture surface and worn surface were examined using field emission scanning electron microscope (FESEM). Hardness of composites increased with increasing wt% of fiber. Tensile strength of composites increased up to 19% for 5 wt% fiber composites. Further addition of fibers decreased the tensile strength of composites. Ductility of the composites decreased with the addition of fibers into the matrix. Wt% of fibers significantly decreased the weight loss, coefficient of friction and wear rate. Also the cumulative weight loss decreased up to 57% for 10 wt% of composites compared to LM6 aluminium alloy. Fracture surface of composite tensile specimen showed dimple formation and fiber pullout. Worn surface of matrix showed long continuous grooves due to local delamination on the surface. However, worn surface of composites showed fine and smooth grooves due to ploughing rather than local delamination. Copper coated steel fiber reinforcement in LM6 aluminium alloy exhibited better mechanical properties and wear resistance compared to matrix.     

Effect of injection timing on the combustion characteristics of rice bran and algae biodiesel blends in a compression-ignition engine

Fuel injection timing is a very important factor among various injection parameters which influences the combustion characteristics of a compression-ignition (CI) engine. This work used a single cylinder CI engine to test the two biodiesel samples rice bran oil methyl esters (ROME) and alga extracted oil methyl esters (AME) for their combustion characteristics influenced by injection timings. The tests were conducted at constant speed (1500?rpm) single cylinder CI engine with three different injection timings (20° before top dead centre [BTDC], 23°?BTDC and 26°?BTDC). The results show increased cylinder pressure and heat release rate when advancing the injection timing at earlier combustion stages. When retarding the injection timing the cylinder pressure and the heat release rate lowers. Compare to AME, the combustion characteristics for ROME shown improved results. The variations in exhaust gas temperature are also depicted.     

Environmental effect on the impact of ferrofluid on Caulerpa Racemosa Oil methyl ester from marine macroalgae

This paper investigated the role of emission characteristics of a diesel engine when ferrofluid blended with Caulerpa Racemosa oil methyl ester (CROME) is used as a fuel. The major problem areas for compression ignition (CI) engines are emissions. Nanofluid using magnetite was synthesized by reacting Iron II (FeCl₂) and Iron III (FeCl₃) in aqueous ammonia (H₅NO) solution to form magnetite ferrofluid (Fe₃O₄). The fuel that was used in the CI engine was prepared comprising 98.7% [CROME], 1% [Fe₃O₄], and 0.3% [(CH₃)₃NOH] by volume. The results show that the CI engine works well and the power outputs are steady running with the biodiesel blends at different loads. The acquired information was studied and it was found that there was a decrease in hydrocarbon (HC), carbon monoxide (CO), nitrogen oxide (NOx), sulfur dioxide (SO₂), and smoke.     

Engine emission characteristics of algal biofuel with micro emulsion

An experimental investigation was conducted in a diesel engine to establish the effects of tetrahydrofuran (THF) with the Caulerpa racemosa algae methyl esters (CRAME) emulsion fuel. THF is added to the CRAME at different proportions such as 1% and 2%. The CRAME was produced from the Caulerpa racemosa algae oil by transesterification process. The aim of the present study was to analyze the experimental exploration of the antioxidants THF on engine emission of a diesel engine fueled with methyl ester of CRA oil. The test is conducted with different antioxidant concentrations of CRAME mixtures. The results exhibited that THF is effectual in controlling emissions.     

Emission analysis of the effect of doped nano-additives on biofuel in a diesel engine

This study was aimed at hybrid nanocatalysts to reduce emissions of a diesel engine fueled with nanocatalyst biodiesel blends. Biodiesel was produced from Prosopis juliflora oil by the transesterification process. The nanocatalyst having cerium oxide on multiwall carbon a nanotube was investigated using biodiesel blends at two concentrations (50 and 100 ppm).The results revealed that the high surface area of the nanoparticles and their proper distribution along with catalytic oxidation reaction resulted in significant overall reductions in the emission. More specifically, all pollutants, i.e., CO, HC, and NOx, and smoke opacity were reduced when compared to B20.     

Cache Optimization on Hot‐Point Proxy Caching Using Weighted‐Rank Cache Replacement Policy

The development of proxy caching is essential in the area of video‐on‐demand (VoD) to meet users' expectations. VoD requires high bandwidth and creates high traffic due to the nature of media. Many researchers have developed proxy caching models to reduce bandwidth consumption and traffic. Proxy caching keeps part of a media object to meet the viewing expectations of users without delay and provides interactive playback. If the caching is done continuously, the entire cache space will be exhausted at one stage. Hence, the proxy server must apply cache replacement policies to replace existing objects and allocate the cache space for the incoming objects. Researchers have developed many cache replacement policies by considering several parameters, such as recency, access frequency, cost of retrieval, and size of the object. In this paper, the Weighted‐Rank Cache replacement Policy (WRCP) is proposed. This policy uses such parameters as access frequency, aging, and mean access gap ratio and such functions as size and cost of retrieval. The WRCP applies our previously developed proxy caching model, Hot‐Point Proxy, at four levels of replacement, depending on the cache requirement. Simulation results show that the WRCP outperforms our earlier model, the Dual Cache Replacement Policy.     

Investigation of the surface properties of heat treated electroless Ni–P coating

Electroless nickel phosphorus (Ni–P) coatings were synthesised from an acid chloride electrolyte. The synthesised coatings were heat treated at different temperatures, and the surfaces of the heat treated coating were characterised using scanning electron microscopy and X-ray diffraction. Adhesion, wettability, hardness and corrosion behaviour of the coatings were measured. The surface morphology showed the formation of a nano crystalline nickel matrix under heat treated condition. X-ray diffraction analysis of the heat treated samples revealed the recrystallisation of nickel and formation of Ni₃P phase in the coatings. The wettabilty study showed that the as-deposited Ni–P coating is hydrophobic and wettability increases to a maximum of 70.8° contact angle for heat treated temperature of 400°C due to nano crystalline formation. The Rockwell C adhesion test revealed the presence of micro cracks with increase in heat treatment temperature, however the failure is within the acceptability limit. The micro hardness of the Ni–P coating increased with increase in heat treatment temperature. Corrosion potential of the Ni–P coating shifted to a positive potential under heat treated conditions owing to oxidation and precipitation of Ni₃P phase. Decreased corrosion rate and corrosion current density (7.37–0.21?µA?cm^?2) is attributed to heat treatment at 400°C.     

A power efficient continuous time ΔΣ modulator with 15 MHz bandwidth and 70 dB dynamic range

A state variable block diagram method is given for the realization of universal biquadratic transfer functions employing second-generation current-controlled conveyors (CCCIIs). Using minimum number of passive components and properly adjusting the bias currents of CCCIIs, the proposed circuits can realize all the tunable frequency standard filter functions: high-pass, band-pass, low-pass, notch-pass, and all-pass by choosing appropriate input branches without changing the passive elements. These presented circuits are in current-mode and voltage-mode separately. The non-ideality analyses of these configurations are given. Additionally, a high-order low-pass filter derived from the proposed voltage-mode biquadratic filter is introduced. PSPICE simulation results are included to verify the theory.     

Predictions of the optimized friction stir spot welding process parameters for joining AA2024 aluminum alloy using RSM

The friction stir spot welding process (FSSW) is a variant of the linear friction stir welding process in which the material is being welded without bulk melting. The FSSW parameters such as tool rotational speed, plunge rate, plunge depth, and dwell time play a major role in determining the strength of the joints. A central composite rotatable design with four factors and five levels was chosen to minimize the number of experimental conditions. An empirical relationship was established to predict the tensile shear fracture load of friction stir spot-welded AA2024 aluminum alloy by incorporating independently controllable FSSW process parameters. Response surface methodology (RSM) was applied to optimize the FSSW parameters to attain maximum lap shear strength of the spot weld.     

Single-stage sine-wave inverter for an autonomous operation of solar photovoltaic energy conversion system

This paper proposes a high performance single-stage inverter topology for the autonomous operation of a solar photovoltaic system. The proposed configuration which can boost the low voltage of photovoltaic (PV) array, can also convert the solar dc power into high quality ac power for driving autonomous loads without any filter. An MPPT circuit with parallel connection is implemented so that the part of the energy generated is processed by the dc–dc converter to supply dc loads. The line current total harmonic distortion (THD) obtained using this configuration is quite reasonable. The proposed topology has several desirable features such as low cost and compact size as number of switches used, are limited to four as against six switches used in classical two-stage inverters. In this paper analysis, simulation and experimental results are presented.