Search

This study is an attempt to close the loop between simulation and reality. Many industries are of the opinion that a simulation does not really predict the actual process and is only a colorful plot for presentation. An accurate simulation can save cost by a multitude of ways like material savings, process optimization, cycle time reduction, improved quality of parts and so on. A validation of the simulation in a real time scenario will instil necessary confidence in the accuracy of the simulation study thereby closing the loop between simulation and reality In the present study, the mold flow analysis is conducted for the back plate of LED emergency light with the help of Autodesk moldflow simulation software to generate the gate location, feed system building, cooling channel wizard, fill time and to check warpage and then the result is verified by superimposing the scan data of the physical part which is scanned in Steinbichler Blue Light 3D Scanner and CAD model in Geomagic verify.

The present work deals with steady state air flow analysis of electric motor having 20 hp rating running at 1450 rpm. The motor is being used to run the belt pull system to drive the exhaust fan in the industry. Air flow analysis of electric motor is carried out to predict temperature distribution over the motor. The modeling of the complete motor is done in CATIA. Meshing of whole geometry is done in ICEM CFD14.5. Results are obtained using FLUENT. In this research only copper losses and iron losses are taken into consideration based on the output obtained from electrical simulation software. The copper and iron losses are found out from electromagnetic analysis using Motorsolve software. Losses are treated as heat source or input to find out temperature distribution. To improve the accuracy, the computational fluid dynamics (CFD) analysis is performed by considering the air flow around casing and fins and thermal generation due to the losses. It is observed that there is a significant rise in temperature on casing and on fins for 30 °C ambient temperature.

Early detection of cancers and their precise subtyping are essential to patient stratification and effective cancer management. Data-driven identification of expression biomarkers coupled with microfluidics-based detection shows promise to revolutionize cancer diagnosis and prognosis. MicroRNAs play key roles in cancers and afford detection in tissue and liquid biopsies. In this review, we focus on the microfluidics-based detection of miRNA biomarkers in AI-based models for early-stage cancer subtyping and prognosis. We describe various subclasses of miRNA biomarkers that could be useful in machine-based predictive modeling of cancer staging and progression. Strategies for optimizing the feature space of miRNA biomarkers are necessary to obtain a robust signature panel. This is followed by a discussion of the issues in model construction and validation towards producing Software-as-Medical-Devices (SaMDs). Microfluidic devices could facilitate the multiplexed detection of miRNA biomarker panels, and an overview of the different strategies for designing such microfluidic systems is presented here, with an outline of the detection principles used and the corresponding performance measures. Microfluidics-based profiling of miRNAs coupled with SaMD represent high-performance point-of-care solutions that would aid clinical decision-making and pave the way for accessible precision personalized medicine.

The elastic properties of a friction material play a significant role in the vibro-acoustic noise, vibration and harshness behaviour of braking systems on a structural scale. Common testing, such as pad compressibility testing and modal testing, allows identification of the global static and dynamic elastic properties respectively, which generally provide data for finite element numerical models. The present investigation presents static and dynamic testing methodology and focuses on the distribution of the elastic properties of friction materials on a pad scale. Besides trying to determine a correlation with bench testing, the added value in updating friction material models with distributed elastic properties for squeal simulation models is evaluated. For investigation of the distribution of the friction material properties of brake pads, quasi-square friction samples of friction materials were collected from several locations of the pad. The experimental meshing provides data on the inner radius and the outer radius of the brake pads as well as on the inlet and the outlet of the pad. For the purpose of this study, six different materials were tested. In addition to four known prototype friction material formulations obtained using the same production process, two commercial friction materials were investigated. The static stiffness is evaluated with a laboratory compression machine set-up whereas the dynamic stiffness is identified from laboratory ultrasonic investigations. The results and coherence of the static and dynamic stiffness distributions obtained by both approaches are compared. The trends with the noise, vibration and harshness bench testing results are also discussed for selected pads. From ultrasonic testing, it is found that the dynamic stiffness distribution can take several forms (flat, concave or convex) which can be different for the in-plane stiffness and the normal stiffness of the pad. It is mainly noticeable along the tangential direction of the pad, reaching a variation of up to 16% between middle of the pad and the edges. The stiffness can also vary by up to 8% along the radial direction of the pad. The measurements performed during this study confirm also that these stiffness distribution patterns are strongly dependent on the formulation friction of the material and on the production process itself. The above-mentioned stiffness distributions were implemented in finite element brake pad models to estimate the potential frequency shift arising from these considerations. The impact of taking into account such information was shown to be limited for the free–free pad modal properties. Nevertheless, the influence of such distributions on the complex eigenvalue analysis of complete finite element brake models was observed and is discussed. Even if the used pad models take into account to some extent the static and dynamic stiffness distributions for complex eigenvalue analysis, they still do not agree with the non-linear material models regarding the stress and the frequency, as shown experimentally. Even if an additional effort is made to determine these stiffness distributions which provide more detailed information for the brake pad finite element models, this physical degree of freedom could drive, to a certain extent, the noise, vibration and harshness responses of the brake systems. A more mature understanding of the influences of the formulations and the process on these distributions and their control at the pad design stage could add a complementary strategy for reduction in the noise, vibration and harshness issues in brake systems.

Air intake is a crucial component for supersonic and hypersonic air breathing propulsion devices. The intake must provide the required mass flow rate of air with minimal loss of stagnation pressure. A major difficulty in the stable operation of an intake is associated with shock wave boundary layer interaction (SBLI). This causes boundary layer separation and adverse pressure gradients which lead to total pressure loss, flow unsteadiness and flow distortion in the intake system. Passive control devices such as micro-ramp, thick-vanes provide better boundary layer control and reduce parasitic drag. The proposed study aims to perform CFD analysis of micro-ramp for hypersonic flows and validate the results with the available experimental data. Two micro ramp models namely MR80 and MR40 are considered for this study. Results obtained show the presence of micro ramp successfully delayed the flow separation and helped to suppress SBLI.

Theoretical computations were performed on the 1,3-dipolar cycloaddition reactions of pyridinium-3-olates and pyrazinium-3- olates with methyl methacrylate employing density functional theory at the B3LYP/6-31G(d) level in the gas phase and in THF. The two possible regioisomeric pathways, forming 6-esters and 7-esters, along with the two stereoisomeric channels, endo and exo, have been considered. Thermodynamic and kinetic parameters calculated at room temperature have been analyzed while the regioselectivity has been interpreted using reactivity indices. The presence of the methyl group on the dipolarophile compared to methyl acrylate, increases the activation energy but decreases the reaction enthalpy in THF. The rate constants of these reactions have been determined using conventional transition state theory. The thermodynamic and kinetic preferences for the reactions of these pyridinium-3-olates and pyrazinium- 3-olates with methyl methacrylate, in the gas phase and THF, decrease in the order 6-exo > 7-exo > 6-endo > 7-endo. On comparing the reactions of pyridinium-3-olates and pyrazinium-3-olates with methyl acrylate, a different order is observed although the 6-exo cycloadduct remains the major product.

Films of soluble collagen extracted from rat‐tail tendon were studied at the solid–solution interface, and the surface energy of the films was evaluated. The films transferred onto solid substrates using the Langmuir–Blodgett film (LB film) technique were characterized using Fourier transform IR attenuated total reflectance spectroscopy and atomic force microscopy. The properties of the protein in contact with different structure modifiers like basic chromium sulfate (BCS) and formaldehyde (HCHO) were analyzed for the effect of various tanning agents on the protein structure. The thermal properties of the films were studied using differential scanning calorimetry. The results show that the film of collagen treated with BCS exhibits an increase in the peak temperature and enthalpy changes compared to the pure collagen as well as the protein with HCHO. These differences are attributed to the changes in the crosslinks arising from both coordinate–covalent and covalent interactions, respectively. The atomic force micrographs showed an increase in order for the collagen film with BCS compared to the HCHO treated analogue. A similar trend is seen in the surface energy parameters of the protein films on solid surfaces on reacting with BCS and HCHO, suggesting a molecular level ordering process in collagen assemblies. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3859–3865, 2004

Gallium, which is extensively used in the production of semiconductor materials, is present at the parts per million level in Bayer's liquor. The low concentration of gallium in the liquor, along with the high concentration of aluminum, prompted the use of chelating ion exchangers as an alternative separation process. A chelating ion exchange resin with hydroxamic groups attached to the copolymer of acrylonitrile-divinylbenzene has been prepared by suspension polymerization followed by hydrolysis and chelation with hydroxylamine hydrochloride. Adsorption studies of gallium, using the above hydroxamic acid resin, were carried out. Adsorption was dependent on particle size of the resin and optimum conditions are determined for obtaining 0.3- to 0.5-mm particles by varying the composition of the emulsion, using a secondary polymerization technique, and adding of diluents. Acrylic acid, as a diluent in the copolymer matrix, was found to increase the particle size and stability of the resin. IR studies, carried out for the products obtained at various stages, confirmed the conversion of polymer to resin with a hydroxamic acid group and its complex formation with gallium. Both batch and column studies were carried out for the determination of the capacity of the resin with synthetic Bayer's liquor containing gallium and commercial Bayer's liquor. Scaled-up column studies were carried out with commercial Bayer's liquor to test the cyclability and stability of the resin. It was observed that chelated ion exchange resin could be recycled up to 30 times. The optimal liquid to solid phase ratio was found to be 1:12. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 847–855, 2004

In recent times, resins with chelating ligands (hydroxamic acids, in particular) have received considerable attention owing to their selective adsorption of gallium from sodium aluminate liquor, commonly known as Bayer liquor. This paper deals with the synthesis of a chelating ion-exchange resin as well as the studies carried out on the resin to ascertain its loading capacity for gallium, kinetics, stability toward acid and alkali besides its recyclability. The paper also gives a description of the ion-exchange cycle besides the design of a laboratory-scale column which shall yield data applicable to the designing of commercial units.

Addition of chemicals during the extraction of cassava starch for enhancing the settling rate, whiteness and compactness of the settled starch is an accepted commercial practice. The effect of addition of selected chemicals such as acids (sulphuric and hydrochloric acids), bleaching and oxidising agents (sodium metabisulphite and sodium hypochlorite) and alum during settling on the thermal and pasting properties of the cassava starch was examined. Treatment with sulphuric acid produced a noticeable increase in all DSC gelatinisation parameters, viz. onset gelatinisation temperature (To), temperature at peak minimum (Tp) and end temperature (Te), with increasing concentration of acid, while only a marginal shift could be obtained even at higher concentration of hydrochloric acid. However, no major effect resulted from treatment with sodium metabisulphite, sodium hypochlorite and alum. The gelatinisation enthalpy was hardly affected by the treatments. An exception was hydrochloric acid, which brought about a perceptible decrease in enthalpy at higher concentrations indicating that starch crystallinity is influenced to a small extent by hydrochloric acid. Pasting characteristics studied using a Rapid Visco Analyser showed that sulphuric acid, even at the lowest concentration (5 mM), considerably affected the structural characteristics of cassava starch, while hydrochloric acid induced similar effect only at higher concentrations. Alum reduced the paste viscosity while the bleaching agents (sodium metabisulphite and sodium hypochlorite) were not so effective in modifying the starch viscosity characteristics.

Combined density functional theoretical (DFT) and ab initio methods have been used for the calculation of ¹³C NMR chemical shifts of some hydrogen-terminated oligomers of ethylene, propylene, isobutylene, ethylene oxide, vinyl alcohol, and acrylonitrile. The ¹³C isotropic chemical shift (δiso) values are calculated with respect to theoretical isotropic shielding constant (σiso) value of the tetramethylsilane (TMS). The average unsigned error in δiso values of the various oligomers varies between 2 and 5 ppm. The error of ca. 5.22 ppm for acrylonitrile arises mainly due to the cyano carbon. Oligomeric approach has been employed to calculate the δiso values of the corresponding polymers. This approach is validated by the excellent correlation obtained for the linear fits. These calculated δiso values for the polymers are in good agreement with the experimental values.

Stability of collagenous matrixes such as skin and leather with respect to changes in their dimensions on heating has long been correlated with degree and type of cross links formed and short-range ordering in angstrom unit scales. Macroscopic dimensional changes may be expected to involve alterations in the long-range order as well as supramolecular assemblies in skin and leather. This study relates thermal shrinkage of skin matrixes with alterations observed in micro-, meso-, and macroporic structures. Changes in the pore structure of skin associated with thermal shrinkage have been studied using nitrogen adsorption and mercury intrusion porosimetry measurements. A comparison of results obtained using both techniques has been made. These results indicate that although the percentage porosity of the matrix decreases, the BET specific surface area increases on shrinkage. An insight into the changes in the pore systems of skin induced by thermal shrinkage has been gained.

Organization of the copolymer obtained from perfluoroalkylethylacrylate and acrylic acid/ester (FCPn, n = 8) and its spreading characteristics have been studied in Langmuir films at the air/water interface using the surface pressure−molecular area (π−A) and surface potential−molecular area (ΔV−A) isotherms. Influence of additives in the interfacial organization and spreading characteristics contributing to significant changes in wetting and adhesion properties of the copolymer film was studied using three types of mixed monolayers with FCP:  polar, nonpolar, and amphiphilic. The polar additives such as 1,4 dioxane or alcohols did not show any effect on the spreading behavior of FCP. Only octadecane (OD) and chloroparaffin (CP) among the nonpolar additives in the surface active class change the organization of the polymer at the air/water interface while octadecane alone changes the interfacial energy drastically. An estimate of the compressional moduli for the pure polymer and the mixed films showed that the presence of octadecane in FCP makes the film more elastic. However there is a critical fraction of OD in the mixture beyond which a phase transition takes place.

Influence of hydrogen-bond-breaking reagents such as urea on shrinkage temperature, isometric tension, swelling behavior, tensile strength, and percentage extension of native rat tail tendon (RTT) were examined. The swelling behavior was observed with polarizing optical microscopy and scanning electron microscopy. The results show that the lyotropic swelling increased the width of the fiber and was associated with the action of urea on the collagen fiber. Hydration properties led to significant variations in the swelling phenomenon. Lyotropic swelling produced opaque, limp, and flaccid fibers that did not change appreciably in length. The melting behavior and the swollen fascicles were clearly seen in scanning electron micrographs of 3 and 6M urea-treated RTT. The reduction in the dimensional stability of native RTT collagen fiber on treatment with urea demonstrated the role of secondary structure in the dimensional stabilization of collagen. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 975–982, 2002; DOI 10.1002/app.10262