An Investigation on Spot-Weld Modeling Complexity for Crash Simulation

In order to design car body structures which are safe during crash, modern automotive manufacturers perform both full-scale experimental crash tests and computer simulation of vehicle crash events using commercially available Finite Element Analysis (FEA) packages such as ABAQUS or LS-DYNA. Use of crash simulations significantly reduces the number of real time crash experiments needed and reduces the time required for design changes. However, in order to capture accurately crash behavior during high-speed impact, a large amount of detailed FEA modeling features such as number and types of elements, mesh element size, number of components, different types of connectors, material properties, and other detailed features are needed. Crash simulation requires explicit time-stepping procedures, which can be computationally expensive for complicated full vehicle models with many components. An important feature in crash simulation is the amount of detail included in modeling spot weld connections. Traditionally for efficiency, simple node-to-node rigid connections for modeling spot weld connections between different components are used, especially when many components are connected in a full vehicle crash model. Recent studies have shown the importance of accurate modeling including elastic stiffness and failure modes for spot welds due to high impact loads in automotive crash analysis. For efficiency and convenience, most commercially available FEA packages now include the option of creating mesh independent spot welds, which allow the user to define the location of the center point of the spot weld and define the spot weld radius on adjacent surfaces of connected components. A distributed coupling to nodes within the radius specified is automatically created which approximates the behavior of a spot weld of finite size. In addition, the size of the rigid spot weld model provides greater accuracy compared to the simple node-to-node connection. However, it has not been until very recent that some researchers and commercially available FEA software have the ability to include important spot weld elastic properties and failure modes combining pull, peal, shear, and torsion. In this work, different levels of complexity in spot weld modeling are examined in terms of sufficient accuracy which can be used efficiently for impact analysis of large connected components and full vehicle crash models. In order of increasing complexity, the following spot weld models are considered and results compared: (a) simple node-to-node rigid connection, (b) rigid mesh independent spot welds, (c) elastic mesh independent spot welds, and (d) elastic with failure mesh independent spot welds. In order to study the fundamental behavior of the different mesh-independent spot weld models, pullout and peal tests between two thin ductile steel plates are performed which isolate different failure modes. Comparisons of reaction force versus displacement curves and internal energy versus displacement for all the different spot weld models are given. Results indicate that the rigid connected results in peak reaction forces which are much larger than elastic spot welds. The spot weld model, which includes failure, follows the same path as the elastic weld but when reaching the particular failure force the reaction remains constant with additional applied displacement. To better understand the behavior of the spot-weld models for crash analysis on a realistic and important automotive component which exhibits complex crushing modes with combined axial and bending a frontal longitudinal rail designed for strength and energy absorption was studied with a node-to-node rigid spot weld compared with mesh independent rigid and elastic spot weld connections. The frontal longitudinal rail is a thin walled closed section located in between the front bumper and the firewall manufactured from two stamped sheets with spot welds on both sides of flanges at discrete intervals along the length. In addition to spot welds, the effect of various shape and size parameter changes including waves, beads, and a small rib for crush initiation that significantly increase energy absorption and crush force efficiency for the rail component are proposed

Electronic Component Cooling Using Jet Aeration

Electronic components play a pivotal part in many industries around the world. They range from the telecommunications industry all the way to the automotive industry. The number of components on a chip has increased many folds and the chip size has decreased through years of research. This is done to ensure more memory can be kept in a computer. But, this has caused an increase of heat generation as there are too many components on a single chip. Thermal management has become very important as the reliability of the component is very important in ensuring greater efficiency. Many electronic component cooling methods have been developed to fasten electronic component cooling. For this project, a method called immersion cooling will be used. However a new way of immersion cooling will be introduced called jet aeration. Jet aerators were used as a device to cool the liquids. The liquids will circulate as one system. The nozzle with a particular velocity of the liquids will hit the water being used. A plunging jet aerator is simply a liquid jet plunging into a pool of liquid and thereby entering the surrounding air into the liquid pool as swarm bubbles. Various sizes of nozzles have been used to investigate the heat dissipated to the air due to the formation of the bubbles. Multi jets were also used to find out whether it can promote better cooling. Comparisons were done through calculations and representations using graphs

Rhodamine-B labeled peptide hormone evaluation by thin layer chromatography

A novel thin layer chromatographic procedure was devised to evaluate the activity of rhodamine-B tagged peptide hormone such as vasopressin & octreotide. Peptide hormones viz. octreotide and vasopressin were added with rhodamine-B (0.2 ml of concentration 2.5mg/ml) and were estimated through thin layer chromatography (TLC) in a concentration and time dependent manner i.e. 25μg, 50μg for 30 & 60 minutes and 4.8μg, 9.6μg for 30 & 60 minutes respectively. The solvent medium used was a mixture of butanol, acetic acid and water in a ratio of 4:1:1. Stationary phase used in this experiment was Silica gel mixed with an inert binder like calcium sulphate and water. Different peptides travel at different rates due to the differences in their attraction to the stationary phase and because of difference in solubility in the solvent. The plates were made to visualize under a UV detector and respective Rf values were calculated. Results showed that rhodamine-B tagged peptides were well seen under UV detector as well as with naked eyes and is an efficacious marker when compared with other developing systems such as ninhydrin, iodine spray etc

Study of starch degrading bacteria from kitchen waste soil in the production of amylase by using paddy straw

The starch degrading amylolytic enzymes are of crucial importance in biotechnology industries with huge application in food, fermentation, textile and paper production. They are universally distribution in bacteria and fungus. Present study aimed at production of pure form of α-amylase from kitchen waste soil with optimization of raw material such as carbon and nitrogen source of the culture media for it. Objective: To evaluate the kitchen waste soil for production of α-amylase with optimization of carbon and nitrogen source required for culture media. Method: The starch degrading bacteria was isolated from the kitchen waste soil environment and was used for production of α-amylase through submerged. The paddy straw extract was shown the best source of carbon and potassium nitrate as the best source of nitrogen with optimum pH 7.0 and temperature of 30ºC. The fermentor parameters were set with the agitator at speed 200rpm with 100% dissolved O2 at fixed temperature and pH. After completion of the fermentation process, the activity of the enzyme was checked by the DNS method. Results: Enzyme produced and purified by this method, was found to have an enzymatic activity of 0.51 mg/ml after column chromatography by nanodrop spectrophotometer and coincide with standard in SDS-PAGE. Here, we have shown the cheap method of commercial production of economically valuable amylase by utilizing paddy straw

Neuropharmacological evaluation of hormones in mice and insilico analysis of melatonin and somatostatin receptors

Spatial learning and memory consolidation are important aspects of human cognition. The test for motor co-ordination in mice is to characterize the motor phenotype of animals and also in relation to human beings. It is among the most fundamental aspects of everyday life as each physiological process that must be performed in order to achieve movement. In this study, depressive effect and effect on learning and memory of the two hormones, melatonin and somatostatin on animals was evaluated using the loco-motor activity test, rotarod and rectangular maze. The effect of Melatonin and Octreotide acetate alone and in combination with each other were estimated in Swiss albino mice. Melatonin was administered dose dependently and time dependently. Octreotide acetate was administered dose dependently. We compared the combined effect of these hormones for motor co-ordination, loco-motor activity and for the memory and learning behavior of animals. As per the present study, we found significant changes in the motor co-ordination, learning, and memory and depressive effect in animals and there was potentiated depression and attenuated learning and memory when the hormones were used in combination. In-silco analysis was conducted using Patchdock software and molecular docking of the ligands to their respective receptors conducted

A Survey of Containner Breeding Mosquito Species in Kuching Area

A visual larval inspection was done from October 2010 to January 2011 to identify the common species of container-breeding mosquitoes in Kuching, Sarawak. A total of 14 areas in Kuching were surveyed. All the 1216 larvae collected were identified. The dominant species was Ae. albopictus (79.03%), followed by Culex sp. (20.97%). The most common breeding sources were plastic containers. The container index was the highest for Taman Budaya, Kuching (83.33%). Larval breeding habitats were found within the temperature range of 25.1⁰C to 33.0⁰C and pH of 3.0 to 9.9. There is no significant difference of water temperature between Ae. albopictus (30.2⁰C ± 1.0) and Culex sp. (30.2⁰C ± 0.6). However, the pH of water for Culex sp. (7.6 ± 0.1) was found significantly lower than that of Ae. albopictus (7.8 ± 0.9). Mean pH of natural containers (6.7 ±1.3) was significantly lower than mean pH for artificial containers (7.8 ± 1.1). Mix breeding of Ae. albopictus and Culex sp. was found in coconut and plant saucers collected from Kampung Kudei and Waterfront, respectively. Based on its dominance and versatility, we suggest that Ae. albopictus may present as a sole vector for dengue virus in Kuching

Sub-micron moulding topological mass transport regimes in angled vortex fluidic flow

Shear stress in dynamic thin films, as in vortex fluidics, can be harnessed for generating non-equilibrium conditions, but the nature of the fluid flow is not understood. A rapidly rotating inclined tube in the vortex fluidic device (VFD) imparts shear stress (mechanical energy) into a thin film of liquid, depending on the physical characteristics of the liquid and rotational speed,ω, tilt angle,θ, and diameter of the tube. Through understanding that the fluid exhibits resonance behaviours from the confining boundaries of the glass surface and the meniscus that determines the liquid film thickness, we have established specific topological mass transport regimes. These topologies have been established through materials processing, as spinning top flow normal to the surface of the tube, double-helical flow across the thin film, and spicular flow, a transitional region where both effects contribute. The manifestation of mass transport patterns within the film have been observed by monitoring the mixing time, temperature profile, and film thickness against increasing rotational speed,ω. In addition, these flow patterns have unique signatures that enable the morphology of nanomaterials processed in the VFD to be predicted, for example in reversible scrolling and crumbling graphene oxide sheets. Shear-stress induced recrystallisation, crystallisation and polymerisation, at different rotational speeds, provide moulds of high-shear topologies, as ‘positive’ and ‘negative’ spicular flow behaviour. ‘Molecular drilling’ of holes in a thin film of polysulfone demonstrate spatial arrangement of double-helices. The grand sum of the different behavioural regimes is a general fluid flow model that accounts for all processing in the VFD at an optimal tilt angle of 45°, and provides a new concept in the fabrication of novel nanomaterials and controlling the organisation of matter

Laser irradiated vortex fluidic mediated synthesis of luminescent carbon nanodots under continuous flow

Published on 15 January 2018.Carbon nanodots (CDs) with size dependent fluorescence are synthesized from multi-walled carbon nanotubes (MWCNTs) under continuous flow in a vortex fluidic device (VFD) when irradiated by a pulsed laser with a wavelength of 1064 nm, without subsequent passivation procedures. The CDs have a relatively narrow size distribution averaging ca. 6 nm in diameter, and have low cytotoxicity and high colloidal stability with the highest emission intensity of the solution at 450 nm under a 345 nm excitation wavelength. Further downstream processing on the as-processed CDs revealed tunability of the emission from 450 nm to 325 nm.Xuan Luo, Ahmed Hussein Mohammed Al-Antaki, Kasturi Vimalanathan, Jillian Moffatt, Kun Zheng, Yichao Zou, Jin Zou, Xiaofei Duan, Robert N. Lamb, Shujun Wang, Qin Li, Wei Zhang and Colin L. Rasto

Fluid dynamic lateral slicing of high tensile strength carbon nanotubes

Lateral slicing of micron length carbon nanotubes (CNTs) is effective on laser irradiation of the materials suspended within dynamic liquid thin films in a microfluidic vortex fluidic device (VFD). The method produces sliced CNTs with minimal defects in the absence of any chemical stabilizers, having broad length distributions centred at ca 190, 160 nm and 171 nm for single, double and multi walled CNTs respectively, as established using atomic force microscopy and supported by small angle neutron scattering solution data. Molecular dynamics simulations on a bent single walled carbon nanotube (SWCNT) with a radius of curvature of order 10 nm results in tearing across the tube upon heating, highlighting the role of shear forces which bend the tube forming strained bonds which are ruptured by the laser irradiation. CNT slicing occurs with the VFD operating in both the confined mode for a finite volume of liquid and continuous flow for scalability purposes

Antibacterial, antifungal, and antiviral effects of three essential oil blends

New agents that are effective against common pathogens are needed particularly for those resistant to conventional antimicrobial agents. Essential oils (EOs) are known for their antimicrobial activity. Using the broth microdilution method, we showed that (1) two unique blends of Cinnamomum zeylanicum, Daucus carota, Eucalyptus globulus and Rosmarinus officinalis EOs (AB1 and AB2; cinnamon EOs from two different suppliers) were active against the fourteen Gram‐positive and ‐negative bacteria strains tested, including some antibiotic‐resistant strains. Minimal inhibitory concentrations (MICs) ranged from 0.01% to 3% v/v with minimal bactericidal concentrations from <0.01% to 6.00% v/v; (2) a blend of Cinnamomum zeylanicum, Daucus carota, Syzygium aromaticum, Origanum vulgare EOs was antifungal to the six Candida strains tested, with MICs ranging from 0.01% to 0.05% v/v with minimal fungicidal concentrations from 0.02% to 0.05% v/v. Blend AB1 was also effective against H1N1 and HSV1 viruses. With this dual activity, against H1N1 and against S. aureus and S. pneumoniae notably, AB1 may be interesting to treat influenza and postinfluenza bacterial pneumonia infections. These blends could be very useful in clinical practice to combat common infections including those caused by microorganisms resistant to antimicrobial drugs