Use of a dynamic mechanical analyzer to study supported polymers

The real and imaginary parts of the complex modulus of polymers which must be supported can be determined with the Du Pont Dynamic Mechanical Analyzer. Polymer coatings of equal thickness are laminated on both sides of a thin metal sheet. The flexural modulus of the laminate is given by E = E₁X³ + E₂(1 ? x³) where E₁ and E₂ are the moduli of the metal and the polymer, respectively, and x is the thickness fraction of metal. Under some conditions, the dynamic viscosity of the polymer can also be determined.     

Soymilk concentration by ultrafiltration: effects of pore size and transmembrane pressure on filtration performance

The effects of membrane pore size and operating pressure on filtration flux, membrane fouling and solute rejections of soymilk during ultrafiltration were studied. Soymilk was concentrated from an initial level of 6.5% solid content to 20% solid content using ultrafiltration membranes. Hollow fibre cross‐flow type cartridges having molecular weight cut‐off (MWCO) as 1, 10 and 30 kDa were used in the experiments. Filtration data were satisfactorily fitted to De La Garza and Boulton's exponential model to find the exponential fouling coefficient (k) and the membrane resistance (R_m). The permeate fluxes obtained in 10 and 30‐kDa MWCO membranes were found to be approximately four times higher than that of 1‐kDa MWCO membrane, at transmembrane pressure between 100 and 240 kPa. The average flux obtained was 0.7, 3.15 and 2.7 L m^?2‐h for 1, 10 and 30‐kDa MWCO membranes, respectively. The R_m value of membranes was found to decrease as the MWCO of membranes increased and transmembrane pressure decreased. The total solid content of permeates obtained by these membranes was between 0.45% and 1.4%. Membrane‐concentrated soymilk was found to have lighter colour and almost half the value of viscosity compared with evaporated milk.     

Fat crystal-stabilized water-in-oil emulsions as controlled release systems

Fat crystal-stabilized water-in-oil emulsions were developed as a controlled release matrix for the delivery of salt. Glycerol monostearate (GMS), glycerol monooleate (GMO) and polyglycerol polyricinoleate (PGPR) were used as emulsifiers and hydrogenated canola oil (HCO) was added as a solid fat. Salt release towards an external aqueous phase was measured via conductivity as a function of temperature. Following 2 h of release at room temperature, the GMS emulsion had the highest encapsulation efficiency followed by the PGPR-HCO, PGPR-only and GMO–HCO emulsions, respectively. The GMS crystals formed Pickering shells around the water droplets that effectively prevented salt transport whereas in the GMO–HCO emulsion, the presence of partial interfacial HCO crystal coverage resulted in lower retention. All crystal-stabilized emulsions showed rapid release of their salt load upon melting of the surrounding solid fat, while little temperature effect was observed with the PGPR-based emulsions. However, these emulsions were sensitive to the presence of a salt concentration gradient whereas the fat crystal-stabilized emulsions showed little response. Overall, this study demonstrated that the spatial distribution of the stabilizing fat crystals (i.e., interfacial vs. continuous phase) as well as the emulsifier type were critical factors controlling salt release patterns.     

Analysis of Failure in Automobile Spokes Manufactured Using Medium Carbon Steel Wires

Medium carbon steel wires are used to manufacture spokes for motor vehicles, and the integrity of the spokes is very important from the point of view of safety to the driver of the vehicle. In this paper, analysis of failure of one batch of spokes has been presented. The spokes failed during assembling on to the wheels and also during the field trials. In order to understand the root cause of these failures, metallurgical investigation of these spokes was done. It involved fractography, scanning electron microscopy, EDS analysis, optical microscopy, hardness testing, tensile testing, and chemical analysis. Chemical composition and tensile properties of the material were found to be within the values mentioned in the specification. The cause of failure is concluded to be the wrong microstructure that got developed in the material. The microstructure of the material is coarse lamellar pearlite with ferrite decorated along the grain boundary. Ferrite being softer is preferentially getting deformed in comparison with the rest of the microstructure i.e., pearlite. This preferential deformation in the material is leading to initiation of cracks during the manufacturing of spoke. Additionally, due to higher lamellar spacing in pearlite, ductility of the material has also decreased.     

Control of Grid Connected Photovoltaic Systems with Microinverters: New Theoretical Design and Numerical Evaluation

This paper addresses the problem of controlling grid connected photovoltaic (PV) systems that are driven with microinverters. The systems to be controlled consist of a solar panel, a boost dc–dc converter, a DC link capacitor, a single‐phase full‐bridge inverter, a filter inductor, and an isolation transformer. We seek controllers that are able to simultaneously achieve four control objectives, namely: (i) asymptotic stability of the closed loop control system; (ii) maximum power point tracking (MPPT) of the PV module; (iii) tight regulation of the DC bus voltage; and (iv) unity power factor (PF) in the grid. To achieve these objectives, a new multiloop nonlinear controller is designed using the backstepping design technique. A key feature of the control design is that it relies on an averaged nonlinear system model accounting, on the one hand, for the nonlinear dynamics of the underlying boost converter and inverter and, on the other, for the nonlinear characteristic of the PV panel. To achieve the MPPT objective, a power optimizer is designed that computes online the optimal PV panel voltage used as a reference signal by the PV voltage regulator. It is formally shown that the proposed controller meets all the objectives. This theoretical result is confirmed by numerical simulation tests.     

Differential diagnosis of Interstitial Lung Diseases using Deep Learning networks

ABSTRACT

An architecture for automatic lung tissue classification method based on the Deep Learning techniques is designed in this paper. Recent works on Deep Learning techniques achieved impressive results in the field of medical image classification. So, we designed a Convolution Neural Network (CNN) for the classification of five categories of Interstitial Lung Diseases (ILD) patterns in High-Resolution Computed Tomography (HRCT) images. The CNN consists of 3 Convolution layers, Leaky ReLU activation followed by Maximum pooling layer and dense layer. The last Fully Connected (FC) layer has 5 outputs equivalent to the classes considered such as Normal, Ground Glass (GG), Emphysema, Micro Nodules, and Fibrosis. The proposed CNN is trained and evaluated on the publicly available ILD database provided by the University Hospitals of Geneva (HUG). Experimental results are compared with the state-of-art, which shows an outstanding performance of the proposed CNN model giving 94.67% accuracy and 94.65% F_avg .     

High-yield chemical synthesis of hexagonal ZnO nanoparticles and nanorods with excellent optical properties

Large yield and low temperature growth of nanostructures are key requirements for fulfilling the demand of large scale applications of nanomaterials. Here, we report a highly efficient chemical method to synthesize high quality hexagonal ZnO nanoparticle and nanorods utilizing the low temperature oxidation of metallic zinc powder in the presence of an appropriate catalyst. This one-step method has advantages such as low temperature (90 degrees C) and atmospheric pressure synthesis and a high yield (> 90%). Microstructure and optical properties of the as-synthesized ZnO nanoparticles are found to be identical or better than those of the commercial ZnO nanopower (Sigma-Aldrich). In particular, in comparison to the commercial nanopowder the as-grown ZnO nanorods and nanoparticles exhibit stronger UV absorption at 376 nm and intense UV photoluminescence emission at -382 nm, with negligible defect emission band. This method is suitable for large-scale production of nanosized ZnO and could be extended for the synthesis of other metal oxides.     

Testing and Diagnosis of Digital Microfluidic Biochips using Multiple Droplets

Digital microfluidic biochip is a promising alternative to the traditional cumbersome laboratory equipment. Such automated biochips are used in many critical applications. Hence dependability is an essential attribute before the chip is in use. Due to mixed integration technologies, these chips have some unique failures. Hence robust offline and online tests are proposed to check the health of the biochips. When a chip undergoes a test in offline mode, then the entire biochip should be available for testing, whereas for the online mode test droplet might be stalled due to unavailability of the next cell in the routing path. However, in both the scenarios one or more droplets route across the chip and the arrival time is also recorded at the destination. So here we have proposed two test schemes to know the correctness of any biochip. Diagnosability is an important feature to find the exact position of the faulty electrode. Our proposed scheme reduces the overall testing and diagnosis time significantly. It also provides an alternative routing path in biochip for fault tolerance.

     

Output feedback control of supercapacitors parallel charging system for EV applications: Theoretical design and experimental validation

In this paper, the problem of controlling parallel charging system with supercapacitors for electric vehicle applications is considered. When the vehicle parks at the station, the charging process of supercapacitors needs to be completed in less than 30 seconds. The control objective is then to tightly regulate the supercapacitors state of charge (SOC) to a given reference constant and to ensure an adequate current sharing between different parallel chargers. Indeed, the current sharing is a critical issue for parallel charging system with supercapacitors, which is a nonlinear system with control inputs constraints. Besides, the SOC depends on the supercapacitors internal voltage, which is not accessible for measurement. Therefore, based on a large‐signal model of the parallel‐chargers‐supercapacitors system, an output feedback controller (combining a state observer and a nonlinear control laws) is designed. The controller is formally shown to meet all objectives, namely, closed‐loop stability, SOC reference tracking, and equal current sharing. The effectiveness of the proposed output feedback controller approach is verified both by simulation and by experimental tests.     

Contributions of TMAH Surfactant on Hierarchical Structures of PVA/Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>–TMAH Ferrogels by Using SAXS Instrument

The magnetic hydrogels combining polyvinyl-alcohol (PVA) and Fe₃O₄ (magnetite)–TMAH (tetra-methyl ammonium hydroxide) have been successfully fabricated via a Freezing-thawing route. The magnetite nanoparticles were prepared from iron sands by using coprecipitation method. The transmission electron microscopy image revealed that the magnetite nanoparticles with a reaction temperature of 30 °C had the average particle size of 12 nm in clusters of aggregation. The result was similar to the particle size obtained from X-ray diffraction data analyzed by Scherer equation. Furthermore, synchrotron small angle X-ray scattering data were analyzed by using two lognormal distributions to calculate the distribution of the individual magnetite particles. Meanwhile, Teubner-Strey and Beaucage models were employed to observe the distribution of magnetite particles coated by TMAH as a surfactant. The data analysis showed that the magnetite particles within the magnetic hydrogels formed aggregations with diameters of cluster particles in the range from 13.1 to 31.8 nm. Interestingly, the diameter of clusters particle increased from 13.1 to 31.8 nm along with the increasing concentration of ferrofluids from 1 to 15 wt%. This phenomenon was predicted to result from the effect of TMAH as a surface reactant agent that prevented the aggregation by coating the surface of the magnetite nanoparticles.