A multi-item transportation problem with fuzzy tolerance

This paper presents the recently introduced modified subgradient method for optimization and its effectiveness in a fuzzy transportation model. Here a multi-item balanced transportation problem (MIBTP) is formulated where unit transportation costs are imprecise. Also available spaces and budgets at destinations are limited but imprecise. The objective is to find a shipment schedule for the items that minimizes the total cost subjected to imprecise warehouse and budget constraints at destinations. The proposed model is reduced to a multi-objective optimization problem using tolerances, then to a crisp single-objective one using fuzzy non-linear programming (FNLP) technique and Zimmermann's method. The above fuzzy MIBTP is also reduced to another form of deterministic one using modified sub-gradient method (MSM). These two crisp optimization problems are solved by Genetic Algorithm (GA). As an extension, fuzzy multi-item balanced solid transportation problems (STPs) with and without restrictions on some routes and items are formulated and reduced to deterministic ones following FNLP and Zimmermann's methods. These models are also solved by GA. Models are illustrated numerically, optimum results of fuzzy MIBTP from two deductions are compared. Results are also presented for different GA parameters.     

Selective Extraction of (−)Epigallocatechin Gallate from Green Tea Leaves Using Two-Stage Infusion Coupled with Membrane Separation

A novel method for the extraction of (−)epigallocatechin gallate of high purity from green tea leaves is proposed in this study. The method comprised a two-stage water-based extraction followed by successive use of microfiltration and ultrafiltration. Microfiltration was used as a pretreatment to ultrafiltration. The best process conditions of each unit operation were estimated by performing well-planned experimentations. The clarified liquor was dried to powder by freeze drying. Chemical analyses revealed that the tea powder contained about 90% of polyphenols. The purity of (−)epigallocatechin gallate was found to be about 80%, while its average yield was 1.22 g/l. The method outlined in this study may have remarkable importance for the bulk production of high-purity (−)epigallocatechin gallate with potential application in pharmaceutical, cosmetic, and food-processing industries. Besides being a green process, this method can be easily scaled up for the commercial production of (−)epigallocatechin gallate.     

Surface Activation and Adhesion Properties of Wood-Fiber Reinforced Thermoplastic Composites

Four surface activation methods were evaluated on a series of wood-fiber reinforced thermoplastic composites (WPCs) as a means to improve the adhesion of a water-based acrylic coating. Treatments with chromic acid and oxygen plasma performed best, increasing the acrylic coating peel load to WPCs by 170 and 122%, respectively, and yielding adhesion levels equivalent to or higher than those obtained on wood. The benzophenone/ultraviolet and flame treatments also improved the coating adhesion by 100 and 64%, respectively, but did not reach the adhesion levels achieved on wood. For both the chromic acid and oxygen plasma treatments, the WPC formulation impacted the treatment efficacy. Profilometry and scanning electron microscopy (SEM) showed that the chromic acid treatment acted mainly by roughening WPC surfaces. While surface oxidation was not evident from attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), the improved wettability of WPCs with water suggested that the oxygen plasma treatment oxidized WPCs.     

Models for minimum ignition temperature of organic dust clouds

The minimum ignition temperature of dust clouds is one of the important factors required for the design of preventive measures against dust explosion. The mathematical models available to predict this parameter have been analyzed for thier application to organic dust clouds. A solution of the most general model proposed by Mitsui and Tanaka is presented, together with its comparision with experimental data. It has been found to be quite successful in predicting the minimum ignition temperature for metal dusts but not for organic dusts. Recommendations for the development of a new model to predict the minimum ignition temperature of an organic dust, such as polyethylene, have been given.     

Industrial fires and explosions due to electrostatic ignition

Static electricity is a frequent source of fires and explosions in industry. A variety of operations may generate static electricity leading to such fires and explosions. This requires adequate preventive and protective measures against this hazard. The present paper describes the theory and mechanism of electrostatic sparking, parameters needed to assess the respective hazard in a plant, safety measures to combat electrostatic problems, common operations where such problems exist and measures to eliminate or mitigate these problems.     

Transition‐Metal Dichalcogenide NiTe2: An Ambient‐Stable Material for Catalysis and Nanoelectronics

By means of theory and experiments, the application capability of nickel ditelluride (NiTe₂) transition‐metal dichalcogenide in catalysis and nanoelectronics is assessed. The Te surface termination forms a TeO₂ skin in an oxygen environment. In ambient atmosphere, passivation is achieved in less than 30 min with the TeO₂ skin having a thickness of about 7 Å. NiTe₂ shows outstanding tolerance to CO exposure and stability in water environment, with subsequent good performance in both hydrogen and oxygen evolution reactions. NiTe₂‐based devices consistently demonstrate superb ambient stability over a timescale as long as one month. Specifically, NiTe₂ has been implemented in a device that exhibits both superior performance and environmental stability at frequencies above 40 GHz, with possible applications as a receiver beyond the cutoff frequency of a nanotransistor.     

Kitkaite NiTeSe,an Ambient-Stable Layered Dirac Semimetal with Low-Energy Type-II Fermions with Application Capabilities in Spintronics and Optoelectronics

The emergence of Dirac semimetals has stimulated growing attention, owing to the considerable technological potential arising from their peculiar exotic quantum transport related to their nontrivial topological states. Especially, materials showing type-II Dirac fermions afford novel device functionalities enabled by anisotropic optical and magnetotransport properties. Nevertheless, real technological implementation has remained elusive so far. Definitely, in most Dirac semimetals, the Dirac point lies deep below the Fermi level, limiting technological exploitation. Here, it is shown that kitkaite (NiTeSe) represents an ideal platform for type-II Dirac fermiology based on spin-resolved angle-resolved photoemission spectroscopy and density functional theory. Precisely, the existence of type-II bulk Dirac fermions is discovered in NiTeSe around the Fermi level and the presence of topological surface states with strong (≈50%) spin polarization. By means of surface-science experiments in near-ambient pressure conditions, chemical inertness towards ambient gases (oxygen and water) is also demonstrated. Correspondingly, NiTeSe-based devices without encapsulation afford long-term efficiency, as demonstrated by the direct implementation of a NiTeSe-based microwave receiver with a room-temperature photocurrent of 2.8 µA at 28 GHz and more than two orders of magnitude linear dynamic range. The findings are essential to bringing to fruition type-II Dirac fermions in photonics, spintronics, and optoelectronics.     

Spatial distribution of atmospheric CO2 absorption detected around 2 µm on the reflectance spectra derived from Hyperion images

This study explores the detectability of atmospheric carbon dioxide (CO₂) absorption at the short wave infrared bands of Hyperion EO-1 hyperspectral images. Two CO₂ absorption bands at around 2.002–2.012 and 2.052 µm, respectively, were identified on the reflectance spectra derived from the images. Considering the principle of differential optical absorption spectroscopy (DOAS) and assuming the O₂-A band around 0.762 µm as reference, the spatial variation of the column density was estimated for Kolkata, a region around 22° 31′ N 88° 21′ E. The ratio of the individual absorption depth of CO₂ to that of O₂, instead of the ratio of their column density, was found to be more suitable to express the spatial distribution of CO₂ concentration over short distance, of the order of metres. The methodology was validated with Orbiting Carbon Observatory-2 (OCO-2) data. The work suggests the inclusion of 2–3 narrowband channels corresponding to O₂-A and CO₂ absorptions in future moderate resolution multispectral sensors in order to facilitate the monitoring of atmospheric CO₂.     

Effect of weathering on physico-chemical properties and combustion behavior of an Indian thermal coal

International Journal of Coal Science & Technology - An open air stockpile of conical shape was formed with 3.5 m base diameter and 5 m height using 500 tons of...