NOPR Collection:

Effect of fibers on the mechanical properties of fly ash and GGBS based geopolymer concrete under different curing conditions

Wed, 01 Feb 2017 00:00:00 GMT

Title: Effect of fibers on the mechanical properties of fly ash and GGBS based geopolymer concrete under different curing conditions Authors: Prabu, B; Kumutha, R; Vijai, K Abstract: This study is aimed at investigating the effect of various curing methods on the mechanical properties of fiber reinforced geopolymer concrete samples. In addition to compressive strength, split tensile strength, flexural strength, impact strength, density and workability are also examined. From the investigation it is found that in the heat curing method, there is only a marginal increase in compressive strength at 28 days when compared with the ambient curing. On the other hand, a drastic increase in compressive strength is found at 3 days because of heat curing due to high geopolymerization process. It is observed that, the compressive strength and density increase with high volume of steel fibers, split tensile and Flexural strengths have similar trend to compressive strength. Page(s): 5-12

A compact dual-band bandpass filter using triple-mode stub-loaded resonators and outer-folding open-loop resonators

Wed, 01 Feb 2017 00:00:00 GMT

Title: A compact dual-band bandpass filter using triple-mode stub-loaded resonators and outer-folding open-loop resonators Authors: Liu, Ming-Qing; Wang, Cong; Kim, Nam-Young Abstract: A compact dual-band bandpass filter with high-selectivity is proposed using triple-mode stub-loaded resonators (TMSLRs) and outer-folding open-loop resonators (OFOLRs). The proposed TMSLRs, with two identical folded shape open-stubs located at the symmetrical sides of a microstrip line, are used to generate the upper band while the OFOLRs are utilized to form the lower passband. Two resonatorsare independent control of passbands, frequencies, and bandwidths.Besides, high selectivity and stopband suppression can be easily obtained due to the fact that four transmission zeros are realized near the passband edges. Measured results show that two central frequencies occurred at 2.4 GHz and 5.4 GHz for WiMAX and WLAN applications with a wide fractional bandwidth of 13.9% and 16.7% and a low insertion loss of -0.25 dB and -1.21 dB, respectively. Page(s): 13-17

Performance evaluation of cubic boron nitride tool in machining of titanium (grade-II) under minimum quantity lubrication

Wed, 01 Feb 2017 00:00:00 GMT

Title: Performance evaluation of cubic boron nitride tool in machining of titanium (grade-II) under minimum quantity lubrication Authors: Gupta, Munish Kumar; Sood, Pardeep Kumar; Sharma, Vishal S Abstract: The advantages of metal cutting fluids in machining are prominent, yet their utilization is accompanied by health and environment hazards. Besides, stringent environmental policies make the manufacturers to change over to dry turning, which is not viable during the machining of sticky material like titanium alloys. Therefore, the usage of minimum quantity lubrication (MQL) can be considered as a possible solution and a one step towards green manufacturing.The aim of this work is to investigate the machinability of titanium (grade-II) alloy with cubic boron nitride (CBN) tool under MQL conditions. The machining tests was performed under varying conditions of process parameters such as cutting speed (V_c), feed rate (f) and side cutting edge angle (approach angle ϕ). The experiments were planned and executed using response surface methodology (RSM). The tangential force (F_c), tool wear (V_Bmax) and power consumption (K) were selected as the response variables. The outcomes demonstrated that the F_c increases with the increase in feed rate and decreases with the increase in cutting speed and approach angle. Whereas the V_Bmax and K increases with the increase in feed rate as well as cutting speed. There is very less effect of approach angle on V_Bmax and K. Moreover, the results have been presented and optimized process parameters are obtained through multiple response optimizations using desirability function approach. In the end, the optimized parameters under MQL conditions are compared with the wet and dry turning. The MQL conditions have shown better results over wet and dry machining. Page(s): 18-26

Prediction of porous Al/SiC nanocomposite creep behavior via the mechanical alloying process

Wed, 01 Feb 2017 00:00:00 GMT

Title: Prediction of porous Al/SiC nanocomposite creep behavior via the mechanical alloying process Authors: Kakhki, Yasaman Saberi; Nategh, Said; Mirdamadi, Shamseddin Abstract: In the present study, mechanical alloying was successfully employed to produce aluminum matrix composite reinforced with nano SiC. Considering the three mechanisms of deformation, welding and fracture of powders which influence the process, the equilibrium time between welding and fracture or the steady state time is an important factor and milling parameters can affect the steady state time. In this study, the steady state time of mechanical alloying of composites with 3.5, 4 and 5 vol% nano reinforcement SiC has been obtained using an X-ray diffraction analyzer, optical microscopy and particle analyzer. Also the compression creep rate of these composites showed the effect of nano SiC reinforcement on compression creep rate decrease and lower steady state time of Al-4vol%SiC and nano SiC clustering on compression creep rate increase and higher steady state time of Al-5vol%SiC composite. On the other hand, mechanical alloying process can predict the compression creep behavior of porous Al/SiC nano composite. Page(s): 27-34