Hibiscus sabdariffa (Roselle): A potential source of bast fiber

Roselle is a bast fiber, and its utilization as a textile fiber for the development of textile products is still scanty. A work has been attempted to develop yarn from Roselle. Fibers were extracted from Roselle bark by decortication and degummed in alkaline medium. The degumming process was optimized based on fiber yield and strength. The degummed fibers were then bleached by the hydrogen peroxide bleaching process. Degummed and bleached fibers were characterized by scanning electron microscope, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. Degumming and bleaching results in enhancement of density, fineness, and brightness of Roselle fiber. A marginal decrease in tenacity of the Roselle fiber was observed after bleaching; however, the strength was not affected by degumming. Fibers were converted into fine yarn in the jute spinning system. The yarn properties inferred that the yarn possessed essential properties for the preparation of apparels and home furnishing.     

Effect of Coiling Temperature on the Microstructure and Mechanical Properties of Hot-Rolled Ti–Nb Microalloyed Ultra High Strength Steel

A novel low carbon Ti–Nb microalloyed hot rolled steel with minimum yield strength of 700 MPa and good balance of stretch-flangeability and impact toughness has been developed by controlled thermo-mechanical processing following thin slab direct rolling route. In the present work, the effects of two coiling temperatures on the resulting microstructure, micro-texture and mechanical properties on this Ti–Nb microalloyed steel have been studied. It is observed that increase in coiling temperature from 520 to 580 °C significantly affects the mechanical properties. Higher dislocation density and increased precipitation along with slightly smaller grain size is observed for 580 °C coiling temperature resulting in about 50 MPa increase in yield and tensile strengths as compared to 520 °C coiling temperature.     

Diverting Electron Fluxes to Hydrogen in Mixed Anaerobic Communities Fed with Glucose and Unsaturated C18 Long Chain Fatty Acids

Hydrogen (H2) production was maximized and methane (CH4) formation was minimized in a mixed anaerobic culture which was maintained at 21°C and fed glucose plus unsaturated long chain fatty acids (LCFAs). The initial pH in the batch reactors was 7.8±0.2. The two LCFAs under consideration included linoleic acid (LA) (two C=C bonds) and oleic acid (OA) (one C=C bond). Hydrogen production was observed when glucose was injected on Day 0 and again after Day 4. The H2 yield in cultures fed LA was less than those receiving OA. The H2 yield reached a maximum of approximately 1.1?mol?H2?mol?1 glucose when the LA level was 2,000?mg?L?1. In the case of OA, a maximum yield of 1.3?mol?H2?mol?1 glucose was attained with 2,000?mg?L?1. The inhibition caused by the addition of LA or OA diverted a fraction of electrons toward proton reduction. Under maximum H2 production conditions in the LA fed cultures the acetate production pathway was repressed, while in cultures fed OA the acetate pathway was dominant. The amount of CH4 produced decreased with increasing H2 production and the major volatile fatty acids detected were acetate, propionate and butyrate. Small quantities of formate were detected only in cultures fed LA after the first glucose injection. As the LCFA concentration increased, the initial glucose degradation rate decreased.     

Study of enhanced DC and analog/radio frequency performance of a vertical super-thin body FET by high-k gate dielectrics

This article reports the DC and analog/radio frequency (RF) response of a newly invented device called vertical super-thin body (VSTB) FET towards high-k (Si₃N₄/HfO₂) and low-k (SiO₂) gate dielectrics in conjunction with the scaling effect through a well-calibrated Sentaurus TCAD tool. At channel length (L_G) of 20 nm, compared to SiO₂, Si₃N₄ improves various DC parameters such as off-state leakage current (I_off), on-current (I_on), on-to-off current ratio (I_on/I_off ratio), subthreshold swing (SS), and drain-induced-barrier-lowering (DIBL) by 77.15%, 26.2%, one order of magnitude, 15.78%, and 36.2%, respectively. On the other hand, a higher improvement is seen in all these DC parameters for the HfO₂ gate dielectric (I_off, I_on, I_on/I_off ratio, SS, DIBL improves respectively by 91.8%, 41.57%, two orders of magnitude, 28.28%, and 62.71%). The underlying physics behind such excellent improvement is explained by the device off-state energy band diagram, electrostatic potential, and channel electron density profile for each dielectric. Further, for all the gate dielectrics considered, the device characteristics were studied for a wide range of L_G from 10 to 50 nm to reveal the scaling impact on the device performance. Irrespective of the gate dielectric material, the device exhibits excellent performance at L_G = 10 nm, which in turn indicates to the brilliant scalability of this new device. Besides, although Si₃N₄ and HfO₂ increase gate capacitance (C_gg)/gate-drain capacitance (C_gd), due to the extremely low values of C_gg/C_gd, enhanced unit gain cut-off frequency, and gain-bandwidth-product is achieved. In addition, the increased transconductance (g_m) of the device applying Si₃N₄/HfO₂ gate dielectric leads to a higher peak value of TGF, intrinsic gain, TFP, GFP, and GTFP. This study intends to expand the fundamental knowledge about such a new device as a VSTB FET and hence, aims to be utilized in the future research of this novel device.     

A neurocomputing model for SODAR structure classification

The manual identification of different types of atmospheric microstructures recorded by SODAR (SOund Detection And Ranging) is a tedious task and can be performed only by an expert with broad experience. To avoid this manual task, a neural network based method of SODAR structure classification system is proposed. This method is developed based on past observations of various meteorological parameters such as temperature, relative humidity and vapour pressure, along with different features computed from the SODAR structure data, which are images representing the dynamics of the planetary boundary layer (PBL). The patterns of these images indicate the structure of different thermal patterns of the atmosphere. We propose a neural network model whose architecture combines multilayer perceptron networks (MLPs) to realize better performance after capturing the seasonality and other related effects in the atmospheric data. We also demonstrate that the use of appropriate features can further improve performance of the prediction system. These observations inspired us to use a feature selection neural network which can select good features online while learning the prediction task. The feature selection neural network is used as a preprocessor to select good features. The combined use of feature selection neural network and MLP, i.e. FSMLP (feature selection multilayer perception) results in a neural network system that uses only very few inputs but can produce a good classifier. Here we develop a real-time system that classifies the SODAR patterns automatically.     

Failure analysis of adhesively bonded tubular joints of laminated FRP composites subjected to combined internal pressure and torsional loading

Abstract

Finite element analysis has been carried in the present research to study individual and combined effect of internal pressure and torsional loading on stress and failure characteristics in case of an adhesively bonded Tubular Single Lap Joints (TSLJ) made of laminated Fiber reinforced polymer (FRP) composite materials. Effect of changing torsional load magnitude on an internally pressurised adhesively bonded TSLJ on interlaminar stresses and onset of different joint fracture modes (adhesion and cohesion failures) has also been studied in the present analysis. Three dimensional stress analysis of the adhesively bonded TSLJ has been carried out through suitable ANSYS Parametric Design Language (APDL) of ANSYS 14.0. Tsai-Wu coupled stress criterion has been used for predicting the onset of joint failures in the TSLJ. It has been observed that stresses (σ_r, σ_θ, σ_z, τ_rz) induced within the joint region under pure internal pressure loading are least affected through introduction of a torsional loading in the TSLJ. However, the stresses (τ_rθ and τ_θz) which are considered to be significant under pure torsional loading get tremendously enhanced due to the varying torsional loading. The interface between the outer tube and adhesive of the TSLJ has been observed to be the most critical bondline interface which is prone to undergo adhesion failure towards the free edges under pure internal loading conditions. However, under pure torsional loading conditions it tends to fracture through adhesion failure towards the clamped edge of the TSLJ. Under combined torsional and internal pressure loading the joint fails towards the clamped edge of the along the critical path which happens to be within the bondline interface, indicating predominance of torsional loading over the pure internal pressure loading. A comparative study based on the magnitude of failure index revealed that torsional loading marginally affects the joint failure as the internal pressure loading improves the compactness of the bonded joint hence improving the resistance of the TSLJ against initiation of joint fractures.     

Nondestructive Evaluation of a Haulage Rope in a Monocable Continuously Moving Passenger Ropeway

The theoretical basis of detecting wire rope anomalies using permanent magnetic field has been fully established. The local faults (LF) such as broken wires and loss of metal area (LMA) signals are provided by nondestructive evaluation instruments. These signals represent the electronic equivalent of the mechanical anomalies present in the wire rope. The saturating magnetic field of the instrument makes the anomalies visible to the magnetic sensors placed around the rope. The condition of a haulage rope (construction 6X19) in a monocable continuously moving passenger ropeway has been studied using this nondestructive method, and the results are presented in this paper.     

In situ assessment of independent wire rope core ropes in cage winders by a nondestructive method

The most widely used method to study the condition of winder ropes is the magnetic nondestructive method. Localized and distributed flaws in winder ropes can be detected by this method. This paper is intended to highlight the findings using such a technique in the case of independent wire rope core rope in two cage winders in a coal mine. The text was submitted by the authors in English.     

Modeling of cylindrical surrounding gate MOSFETs including the fringing field effects

A physically based analytical model for surface potential and threshold voltage including the fringing gate capacitances in cylindrical surround gate(CSG) MOSFETs has been developed.Based on this a subthreshold drain current model has also been derived.This model first computes the charge induced in the drain/source region due to the fringing capacitances and considers an effective charge distribution in the cylindrically extended source/drain region for the development of a simple and compact model.The fringing gate capacitances taken into account are outer fringe capacitance,inner fringe capacitance,overlap capacitance,and sidewall capacitance.The model has been verified with the data extracted from 3D TCAD simulations of CSG MOSFETs and was found to be working satisfactorily.     

Analytical threshold voltage and subthreshold swing model for TMG FinFET

An analytical modelling of the subthreshold surface potential, threshold voltage (V_T) and subthreshold swing (SS) for a triple material gate (TMG) FinFET is presented. The basis of the 3D solution is two separate 2D solutions. The FinFET is separated into two 2D structures: asymmetric triple material double gate (TMDG) and symmetric TMDG MOSFETs. Their potential distributions are obtained by solving the corresponding 2D Poisson’s equations. The potential distribution in TMG FinFET is obtained by a parameter-weighted sum of the two 2D solutions. Utilising the concept of minimum source barrier as the leakiest channel path, the minimum value of the surface potential is developed from the potential model. This leads to the derivations for the threshold voltage and SS. Furthermore, the effects of variation in gate work function and gate length are investigated for analytically developed SS and V_T models. Our models are validated against TCAD Sentaurus-simulated results and found to be quite accurate.