Techno India

About: Techno India is a based out in . It is known for research contribution in the topics: Computer science & Cloud computing. The organization has 4724 authors who have published 4005 publications receiving 34112 citations.

Automatic feature recognition and tool path strategies for enhancing accuracy in double sided incremental forming

Abstract: Incremental sheet forming (ISF) has demonstrated significant potential to form complex three-dimensional parts without using component-specific tools and is suitable for economically fabricating low-volume functional sheet metal parts. Single-point incremental forming (SPIF) uses only one tool to form components and requires additional setup to form complex geometries. Double-sided incremental forming (DSIF), using two tools (one on either side of the sheet), can form features from top and bottom of sheet in single setup. While forming components with multiple features, the accuracy of component depends on the tool path strategy used for each feature and sequence in which features are formed. Methodologies are developed to recognise features from free-form components modeled using single and/or multiple surfaces. Recognised features are sliced using horizontal, inclined or offset strategies (developed during the present work) based on the geometrical characteristics of a given feature. Selection of best-forming sequence is automated based on the relation between features and process mechanics. Results presented in this paper show that complex free-form geometries can be formed with good accuracy using proposed methodologies. Maximum deviation between the measured and ideal profiles is less than 400 μm, while using right sequence and appropriate tool path strategy.

Hidden access structure ciphertext policy attribute based encryption with constant length ciphertext

Abstract: In Cipher text Policy Attribute Based Encryption (CP-ABE) scheme, a user is able to decrypt the cipher text only if the pre-specified access structure (also called ciphertext policy) in the ciphertext, matches the attributes defined in the secret key. However, the limitation of the scheme is that the receiver's anonymity is sacrificed as the access structure of the ciphertext reveals the same. The obvious solution to this problem as proposed by proposed by Nishide et al, is to hide ciphertext-policy (hidden access structure). However, although this solution uses reasonably computable decryption policies, it generates the ciphertext of size that is at least, linearly varying with the number of attributes. It also requires additional pairing operations during decryption. We attempt to overcome these limitations in the proposed scheme viz. Ciphertext Policy Attribute Based Encryption with Constant Length (CP-ABE-CL). In our scheme, the ciphertext and secret key remain constant in length, irrespective of the number of attributes chosen. In addition, the decryption algorithm requires fewer and fixed number of pairing operations. Our scheme works for a threshold case: the number of attributes (excluding wildcard attributes) in a policy must be a subset of attributes in a secret key. The proposed scheme supports the positive, negative and wildcard attributes in policy.

Optimization of Parameters to Improve the Properties of AA7178/Si3N4 Composites Employing Taguchi Approach

Abstract: In the recent days, the employ of aluminum alloy has enriched dramatically especially in engineering applications extensively employed in ship building, aerospace, structural, non-structural and automotive applications like driveshaft, wheels, crankshaft, connecting rod, chassis, brake rotors, cylinder blocks and piston etc. The foremost objective of this evaluation is to optimize the impacts of stir casting parameters of Aluminium Alloy AA7178/Si3N4 with response of tensile strength by utilizing Taguchi approach. MINITAB software was employed for conducting the Taguchi analysis. The stir casting parameters of this examination are stirring speed, stirring time and reinforcement percentage. The tensile behaviour of AA7178/Si3N4 composites for varying filler mass proportionate, stirring speed and stirring time were assessed employing a “universal testing machine”, and using a L9 (3)3 Taguchi orthogonal array. The nine samples of trials are employed to estimate the tensile behaviour of the composite material. The Analysis of Variance (ANOVA) is extensively assistance to intimate which parameter is highly impact for this evaluation. Amid those factors, filler content as highly influenced factor to response value followed as stirring time and stirring rpm.

Synthesis and characterization of liquid crystalline polymers containing aromatic ester mesogen and a nonmesogenic ferrocene unit in the spacer

Abstract: A new series of liquid crystalline polymers containing aromatic triad ester mesogen and 1,1′-disubstituted ferrocene as a nonmesogenic unit along with polymethylene spacer was synthesized. The polymer was synthesized by a room temperature polycondensation reaction between bis(4-chloroformyl phenyloxy alkyl ferrocene dicarboxylate) and quinol. The alkyl groups have been varied by an even number of methylene groups with a range from two to ten groups. All the polymers were found to possess liquid crystalline properties. The identification of the mesophase is more transparent with an increase in the spacer. The thermal characteristics were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results reveal that the thermal stability of the polymers was decreased with increasing spacer length. The Tg, Tm, and Ti of the polymers decreased with increasing methylene groups. The incorporation of the ferrocene moiety also has a considerable effect on the glass transition temperature. The char yield of the polymer decreases with an increasing methylene chain length. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3494–3501, 2002

Mechanical and Microstructural Characterization of Friction Stir Welded SiC and B4C Reinforced Aluminium Alloy AA6061 Metal Matrix Composites

Abstract: This study focuses on the properties and process parameters dictating behavioural aspects of friction stir welded Aluminium Alloy AA6061 metal matrix composites reinforced with varying percentages of SiC and B4C. The joint properties in terms of mechanical strength, microstructural integrity and quality were examined. The weld reveals grain refinement and uniform distribution of reinforced particles in the joint region leading to improved strength compared to other joints of varying base material compositions. The tensile properties of the friction stir welded Al-MMCs improved after reinforcement with SiC and B4C. The maximum ultimate tensile stress was around 172.8 ± 1.9 MPa for composite with 10% SiC and 3% B4C reinforcement. The percentage elongation decreased as the percentage of SiC decreases and B4C increases. The hardness of the Al-MMCs improved considerably by adding reinforcement and subsequent thermal action during the FSW process, indicating an optimal increase as it eliminates brittleness. It was seen that higher SiC content contributes to higher strength, improved wear properties and hardness. The wear rate was as high as 12 ± 0.9 g/s for 10% SiC reinforcement and 30 N load. The wear rate reduced for lower values of load and increased with B4C reinforcement. The microstructural examination at the joints reveals the flow of plasticized metal from advancing to the retreating side. The formation of onion rings in the weld zone was due to the cylindrical FSW rotating tool material impression during the stirring action. Alterations in chemical properties are negligible, thereby retaining the original characteristics of the materials post welding. No major cracks or pores were observed during the non-destructive testing process that established good quality of the weld. The results are indicated improvement in mechanical and microstructural properties of the weld.