Dissimilar Impact Welding of 6111-T4, 5052-H32 Aluminum Alloys to 22MnB5, DP980 Steels and the Structure–Property Relationship of a Strongly Bonded Interface

Metallurgical and Materials Transactions A - The ability to weld high-strength aluminum to high-strength steel is highly desired for vehicle lightweighting but difficult to attain by conventional...     

A MULTIGRID-ACCELERATED THREE-DIMENSIONAL TRANSIENT-FLOW CODE AND ITS APPLICATION TO A NEW TEST PROBLEM

A multigrid-assisted solver for the three-dimensional time-dependent incompressible Navier-Stokes equations on graded Cartesian meshes is developed. The spatial accuracy is third-order for the convective terms and fourth-order for the viscous terms, and a fractional-step strategy ensures second-order time accuracy. To achieve good time-wise efficiency a multigrid technique is used to solve the highly time-consuming pressure-Poisson equation that requires to be solved at every time step. The speed-up achieved by multigrid is shown in tabular form. The performance and accuracy of the code are first ascertained by computing the flow in a single-sided lid-driven cubic cavity with good grid-economy and comparing the results available in the literature. The code, thus validated, is then applied to a new test problem we propose and various transient and asymptotically obtained steady-state results are presented. Given the care taken to establish the credibility of the code and the good spatio-temporal accuracy of the discretization, these results are accurate and may be used for ascertaining the performance of any computational algorithm applied to this test problem.     

Querying in Packs: Trustworthy Data Management in Ad Hoc Networks

We describe a trust-based data management framework enabling mobile devices to access the distributed computation, storage, and sensory resources available in pervasive computing environments. Available resources include those in the fixed surrounding infrastructure as well as services offered by other nearby mobile devices. We take a holistic approach that considers data trust, security, and privacy and focus on the collaborative mechanisms providing a trustworthy data management platform in an ad hoc network. The framework is based on a pack formation mechanism that enables collaborative peer interactions using context information and landmarks. A pack provides a routing substrate allowing devices to find reliable information sources and coordinated pro-active and reactive mechanisms to detect and respond to malicious activity. Consequently, a pack forms a foundation for distributed trust management and data intensive interactions. We describe our data management framework with an emphasis on pack formation in mobile ad hoc networks and present preliminary results from simulation experiments.     

米曲霉发酵大米中抗氧化物质对酪氨酸酶的抑制作用

本实验采用两种不同米曲霉菌种(Aspergillus soji,A.orgzae)在35℃和湿度>90%的条件下对大米进行固态发酵6 d,比较发酵大米在发酵过程中活性物质的金属螯合、多酚氧化酶抑制、氧自由基吸收能力及总酚含量的变化。A.orgzae发酵的大米在金属螯合、多酚氧化酶抑制和氧自由基吸收能力上优于A.soji,两者在总酚含量上没有较大差别,且在发酵第4 d时大米的上述四项活性都趋于稳定,故选取A.orgzae发酵4 d的大米探讨其所含活性物质对酪氨酸酶的抑制作用。采用Lineweaver-Burk双倒数法探讨A.orgzae发酵大米中活性物质对蘑菇酪氨酸酶催化L-多巴氧化的抑制作用并推测其抑制机理。同时,虾血淋巴和虾黑变的抑制实验也证明了米曲霉发酵大米对酪氨酸酶的有效抑制作用。     

Phishing website detection using support vector machines and nature-inspired optimization algorithms

Telecommunication Systems - Phishing websites are amongst the biggest threats Internet users face today, and existing methods like blacklisting, using SSL certificates, etc. often fail to keep up...     

Selection of Superior Tillage and Fertilizer Practices Based on Rainfall and Soil Moisture Effects on Pearl Millet Yield under Semiarid Inceptisols

Based on seven field experiments of pearl millet with nine treatment combinations of tillage and fertilizer nutrients conducted during 2000–2006 in a semiarid inceptisol at Agra, an assessment is made in this paper about sustainability of treatments using rainfall received during the crop growing period and available soil moisture at sowing, 20, 40, and 60?days after sowing (DAS) and harvest. Three practices, each of tillage: conventional tillage+mechanical weed control, low tillage+mechanical weed control, and low tillage+mechanical weed control+herbicide; and fertilizer application of 60?kg?N [farm?yard?manure?(FYM)]+40?kg?P/ha, 30?kg?N (FYM)+30?kg?N (urea)+40?kg?P/ha and 60?kg?N (urea)+40?kg?P/ha were tested in the same site over seven years. The F-test indicated significant soil moisture differences on different DAS and also between different tillage treatments. Significant yield differences were found among treatments of tillage and fertilizer and their interaction in all seasons, except 2001 and 2002. Treatment-wise correlation of yield with monthly rainfall received in June–September and available soil moisture on different DAS indicated that September rainfall had a negative and significant correlation with yield attained by tillage and fertilizer treatments. The soil moisture at 20 DAS had a negative and significant correlation with yield under all treatments except conventional tillage+mechanical weed control. The soil moisture at 60 DAS and harvest had a positive and significant correlation with yield attained under different tillage and fertilizer treatments. Regression models of yield were calibrated for tillage and fertilizer treatments through monthly rainfall during July–September and soil moisture on different DAS. The predictability of yield improved significantly by inclusion of both rainfall and soil moisture variables in the models compared to either of the two groups of variables. Ranks were assigned to tillage and fertilizer treatments for yield attained in individual years and mean yield, prediction error, and sustainable yield index over years. The study indicated that conventional tillage+mechanical weed control among tillage together with 30?kg?N (FYM)+30?kg?N (urea)+40?kg?P/ha was superior with a minimum rank sum compared to other treatments. The treatment gave a maximum sustainable yield of 1,683?kg/ha with a net return of Rs 5,670?ha, benefit–cost ratio of 1.16, and sustainable yield index of 47.2% under semiarid inceptisols of Agra.     

Triglyceride composition of Entada phaseolides seed oil

Fatty acid and triglyceride compositions of Entada phaseolides seed oil have been determined by combination of the techniques of systematic crystallisation at low temperatures, pancreatic lipase hydrolysis and gas-liquid chromatography of methyl esters. The percentages of individual fatty acids were found to be myristic 0.3, palmitic 9.1, stearic 4.4, arachidic 1.7, behenic 1.6, oleic 35.8, linoleic 46.7 and linolenic 0.4. The special characteristic of this oil is its content of 6.9, 9.6, 17.0, 19.2, 5.0, 24.1 and 10.4% of monosaturated diolein, monosaturated dilinolein, saturated oleo linolein, dioleo-linolein, triolein, oleo dilinolein and trilinolein, respectively. This investigation has indicated that the 2-position of the triglyceride is preferentially esterified with C₁₈ unsaturated acids and linoleic acid shows preference over oleic acid.     

Integrated semiconductor nanocrystal and epitaxical nanostructure systems: structural and optical behavior

Integration of semiconductor epitaxical nanostructures and nanocrystals into two classes of quantum structures, uncovered adsorbed nanocrystals or buried via epitaxical overgrowth, is successfully demonstrated through structural and optical studies. The combination InGaAs/GaAs epitaxical structures and InAs nanocrystals is employed as a vehicle with the functional aim of exploiting the well developed optoelectronic communication technology based on the former with the biochemical and biomedical applications for which the latter are well suited.     

Tuning Fluidic Resistance via Liquid Crystal Microfluidics

Flow of molecularly ordered fluids, like liquid crystals, is inherently coupled with the average local orientation of the molecules, or the director. The anisotropic coupling—typically absent in isotropic fluids—bestows unique functionalities to the flowing matrix. In this work, we harness this anisotropy to pattern different pathways to tunable fluidic resistance within microfluidic devices. We use a nematic liquid crystalline material flowing in microchannels to demonstrate passive and active modulation of the flow resistance. While appropriate surface anchoring conditions—which imprint distinct fluidic resistances within microchannels under similar hydrodynamic parameters—act as passive cues, an external field, e.g., temperature, is used to actively modulate the flow resistance in the microfluidic device. We apply this simple concept to fabricate basic fluidic circuits, which can be hierarchically extended to create complex resistance networks, without any additional design or morphological patterning of the microchannels.     

Slurry Erosion Performance of Ni-Al2O3 Based Thermal-Sprayed Coatings: Effect of Angle of Impingement

In this paper, slurry erosion performance of high velocity flame-sprayed Ni-Al₂O₃ based coatings was evaluated. The coatings were deposited on a hydroturbine steel (CA6NM) by varying the content of Al₂O₃ in Ni. Using jet-type test rig, erosion behavior of coatings and bare steel was evaluated at different impingement angles. Detailed investigation of the surface morphology of the eroded specimens was undertaken using SEM/EDS to identify potential erosion mechanism. A parameter named “erosion mechanism identifier” (ξ) was used to predict the mode of erosion. It was observed that the coating prepared using 40 wt.% of Al₂O₃ showed a highest resistance to erosion. This coating enhanced the erosion resistance of the steel by 2 to 4 times. Spalling in the form of splats and chunks of material (formed by interlinking of cracks) along with fracture of Al₂O₃ splats were identified as primary mechanisms responsible for the loss of coating material. The erosion mechanism of coatings and bare steel predicted by ξ was in good agreement with that observed experimentally. Among different parameters, $ \left( {K_{\text{IC}}^{2} H} \right)^{1/3} $ , a function of fracture toughness (K _IC) and hardness (H) showed excellent correlation with erosion resistance of coatings at both the impingement angles.