HMMCs are significantly influenced by the reinforcements. Composites with two or more reinforcements and finer grain structures are extensively used due to improved mechanical and tribological properties. The evolutio...HMMCs are significantly influenced by the reinforcements. Composites with two or more reinforcements and finer grain structures are extensively used due to improved mechanical and tribological properties. The evolution of finer and uniform microstructures is strongly dependent on the cooling rate during solidification. In this investigation stir cast hybrid composites of aluminum alloy LM13 was fabricated with garnet and carbon particulate reinforcements. Chills of various materials such as copper, steel, iron and silicon carbide was used to accelerate the solidification. Combination of dispersoid varies from 3 wt% to 12 wt% in steps of 3 wt% garnet and 3 wt% carbon particulates. Microstructure characterization and mechanical properties such as hardness and ultimate tensile strength of reinforced hybrid composites were examined. The test specimens are prepared and tested as per American society for testing and materials (ASTM) standard. Vickers hardness measurement was carried out to study the hardness of the composite. The effect of chill and reinforcement characteristics was presented and compared with the hybrid composite without chill material. The results confirm the positive relationship between mechanical behavior and the dispersiod content. The copper chill cast composite with 9 wt% garnet and 3 wt% carbon was found to increase mechanical properties.展开更多
Fractal antennas are characterized by space filling and self-similarity properties which results in considerable size reduction and multiband operation as compared to conventional microstrip antenna. This paper outlin...Fractal antennas are characterized by space filling and self-similarity properties which results in considerable size reduction and multiband operation as compared to conventional microstrip antenna. This paper outlines a multiband antenna design based on fractal concepts. Fractal antennas show multiband behavior due to self-similarity in their structure. The plus shaped fractal antenna has been designed on a substrate of dielectric constant €r = 4.4 and thickness 1.6mm. The proposed antenna is characterized by a compact size and it is microstrip feed fractal patch of order 1/3. It is observed that the antenna is radiating at multiple resonant frequencies. The resonant frequency is reduced from 2.2 GHz to 900 MHz after I & II iterations respectively. Thus considerable size reduction of 81.77% & overall bandwidth of 12.92% are achieved. The proposed antenna is simulated using the method of moment based commercial software (IE3D) and it is found that simulated results are in good agreement with the experimental results.展开更多
文摘HMMCs are significantly influenced by the reinforcements. Composites with two or more reinforcements and finer grain structures are extensively used due to improved mechanical and tribological properties. The evolution of finer and uniform microstructures is strongly dependent on the cooling rate during solidification. In this investigation stir cast hybrid composites of aluminum alloy LM13 was fabricated with garnet and carbon particulate reinforcements. Chills of various materials such as copper, steel, iron and silicon carbide was used to accelerate the solidification. Combination of dispersoid varies from 3 wt% to 12 wt% in steps of 3 wt% garnet and 3 wt% carbon particulates. Microstructure characterization and mechanical properties such as hardness and ultimate tensile strength of reinforced hybrid composites were examined. The test specimens are prepared and tested as per American society for testing and materials (ASTM) standard. Vickers hardness measurement was carried out to study the hardness of the composite. The effect of chill and reinforcement characteristics was presented and compared with the hybrid composite without chill material. The results confirm the positive relationship between mechanical behavior and the dispersiod content. The copper chill cast composite with 9 wt% garnet and 3 wt% carbon was found to increase mechanical properties.
文摘Fractal antennas are characterized by space filling and self-similarity properties which results in considerable size reduction and multiband operation as compared to conventional microstrip antenna. This paper outlines a multiband antenna design based on fractal concepts. Fractal antennas show multiband behavior due to self-similarity in their structure. The plus shaped fractal antenna has been designed on a substrate of dielectric constant €r = 4.4 and thickness 1.6mm. The proposed antenna is characterized by a compact size and it is microstrip feed fractal patch of order 1/3. It is observed that the antenna is radiating at multiple resonant frequencies. The resonant frequency is reduced from 2.2 GHz to 900 MHz after I & II iterations respectively. Thus considerable size reduction of 81.77% & overall bandwidth of 12.92% are achieved. The proposed antenna is simulated using the method of moment based commercial software (IE3D) and it is found that simulated results are in good agreement with the experimental results.
