Experimental investigation of hexagonal boron nitride filled friction composites using a pin on disc tribometer

Journal of Mechanical Science and Technology - In earlier friction composites, higher thermal conductive copper and copper-based alloys were the main functional fillers to regulate stable friction...     

Bio-PUF-MAC authenticated encryption for iris biometrics

Biometrics is one of the ways for human authentication. Fabrication of biometrics by intruders, limits the accuracy of authentication. The user-specific keys (ie,) pseudo-random numbers give more security for biometric template protection and increase the accuracy of authentication also. The user-specific token or keys can also be fabricated by intruders by any of the prediction methods. To avoid the creation of fake biometric and fake user-specific keys, a device-specific Physical Unclonable Function (PUF) is proposed. In this article, iris authentication is provided by unclonable PUF-based true random numbers to enhance the unique authentication. Nonreversible Message Authentication Codes (MAC) are developed using PUF and Discrete Wavelet Transform features of iris biometrics. Systematically, MAC codes also created with, encryption algorithm. Encryption is additionally providing confidentiality in the individual iris. Experiments are done with CUHK Iris Image Dataset. Proposed Bio-PUF system has significant functional advantages in point of view of the unclonable pseudo-random number from PUF. Experimentally, Avalanche effect, entropy, NCPR, and UACI parameters are analyzed with PUF-based crypt functions. For 75% of matching with the Bio-PUF-MAC codes with enrolment, the accuracy for correct identification is 77.73%.     

Fatigue failure of pb-free electronic packages under random vibration loads

The electronic equipment are used in several fields like, automotive, aerospace, consumer goods where they are subjected to vibration loads leading to failure of solder joints used in these equipment. This paper presents a methodology to predict the fatigue life of Pb-free surface mounted BGA packages subjected to random vibrations. The dynamic characteristics of the PCB, such as the natural frequencies, mode shapes and damping ratios were determined. Spectrum analysis was used to determine the stress response of the critical solder joint and the cumulative fatigue damage accumulated by the solder joint for a specific duration was determined.     

Tuning the morphology of PVDF membranes using inorganic clusters for oil/water separation

Polyvinylidene fluoride (PVDF) membranes with modified membrane morphology were prepared by phase inversion process using iron alkoxide as a novel pore-forming additive (PFA). Higher pure water flux was observed for PVDF/PFA (iron alkoxide) membranes treated with 5% HCl, due to higher porosity produced by the leaching out of the iron alkoxide additive. The untreated membrane containing 0.04% iron alkoxide showed ~99% efficiency oil removal from a surfactant-stabilized oil–water emulsion. After acid treatment, there was a slight decrease in the rejection efficiency (~96.5%); however, this membrane still exhibited the highest emulsion flux. The fouling propensity of the membrane with 0.04 wt % iron alkoxide tested in a crossflow condition decreases indicating a lower amount of oil adsorbed onto the surface and a greater flux recovery ratio. The treated membranes showed appreciable anti-biofouling property when the membranes were challenged with Escherichia coli and Bacillus subtilis obtained from freshwater and/or seawater. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47641.     

Improvement of shelf-life of buffalo meat using lactic acid, clove oil and vitamin C during retail display

Buffalo meat steaks dipped in either (1) distilled water (control), (2) lactic acid (LA), (3) LA + clove oil (clove), or (4) LA + clove + vitamin C (Vit C) were displayed at 4 ± 1 °C, illuminated by a standard fluorescent lamp. The pH, 2-thiobarbituric acid reactive substances (TBARS), instrumental colour (CIE L^∗, a^∗, b^∗), aerobic plate counts (APC), psychrotrophic counts (PPC), coliform counts and sensory colour and odour were determined up to 12th day of display at 3 days interval. Results showed that, all the treatments have significantly (P < 0.05) reduced the TBARS values compared to control. Among treatments, use of LA + clove has exhibited significantly (P < 0.05) lowest TBARS values throughout display period than others. Buffalo meat steaks treated with either LA + clove or LA + clove + Vit C had significantly (P < 0.05) lower APC, PPC and coliform counts than control or LA treated samples. LA + clove + Vit C treated samples maintained significantly (P < 0.05) higher a^∗ and b^∗ values during display as well as improvement in sensory colour and odour than others. Treatment with either LA + clove or LA + clove + Vit C extended the display life of buffalo meat steaks at 4 ± 1 °C. There appears to be a significant advantage to using LA + clove or LA + clove + Vit C over LA alone.     

Nonalloyed Al ohmic contacts to MgxZn1−xO

Al nonalloyed ohmic contacts were fabricated and characterized on Mg_xZn_1−xO (0≤×≤0.34) epilayers, which were grown on R-plane sapphire substrates by metal organic chemical vapor deposition (MOCVD). Specific contact resistances were evaluated by the transmission line method (TLM). A specific contact resistance of 2.5×10⁻⁵ Ωcm² was obtained for Al contact to ZnO with an electron concentration of 1.6×10¹⁷ cm⁻³. The current flow mechanism was studied by investigating the dependence of specific contact resistances on electron concentration and on temperature. For Al contact to Mg_0.34Zn_0.66O, specific contact resistance values are two orders of magnitude larger than that of Al ohmic contacts to ZnO.