Precombustion Cleaning of Coal By Triboelectric Separation of Minerals

In one method of electrostatic beneficiation, pulverized coal is tribocharged by contact with electrically grounded copper. Coal maceral and mineral particles charge with positive and negative polarities, respectively. The charged particles are passed through a separator consisting of two plate electrodes, across which a high voltage is applied, and the positively charged coal particles are separated from the negatively charged mineral particles. The efficiency of separation is dependent upon coal bulk and surface composition, and fineness of grind. Analyses of total sulfur and ash content of the charge-separated particles were used to evaluate beneficiation success of the Illinois No. 6 and Pittsburgh No. 8 coals studied. Two-stage beneficiation demonstrated improved separation. Exposing coal powders to chemical vapors of SO 2 , NH 3 , or acetone prior to beneficiation did not enhance beneficiation.     

Composition control in laser surface alloying

Laser surface alloying, a process of growing interest for local surface modification, relies upon a suitable composition and microstructure for satisfactory on-the-job performance. This paper reports the results of an initial systematic study of laser surface alloying nickel onto AISI 1020 steel substrates using a statistical experimental design technique. The objective was to relate processing conditions to dimensions, solute content, and microstructural refinement of the laser alloyed zones. Solute content was of principal concern as it is the single most important factor affecting the properties of laser surface alloys. The effects of varying the laser power, beam diameter, and speed on the width, depth, nickel content, and fluctuations in nickel content are reported. Interactions between process parameters are discussed, the reproducibility assessed, contour plots for solute content drawn. Dimensionless plots are developed that relate average solute content and microstructural refinement to process parameters. Previously published data for alloying chromium into 1018 steels are shown to contain similar trends. It is felt that such an approach would facilitate selection of processing conditions to obtain reproducibly the compositions and microstructures necessary for gainful utilization of laser surface alloys.     

Dispersion of contaminant in oscillatory flow through a pipe — Computation of moments

Summary Finite—difference implicit scheme is adopted to solve the Aris-moment equations of dispersion of solute in an oscillatory flow through a pipe for all time. Mean concentration distribution have been calculated from first four central moments by using Hermite polynomials and the deviations from Gaussianity have also been examined for unsteady flow.With 3 Figures     

cFEM: a cluster based feature extraction method for network intrusion detection

International Journal of Information Security - The recent trend in network intrusion detection leverages key features of machine learning (ML) algorithms to detect network traffic anomalies....     

Effect of algal and bacterial diet on methyl mercury concentrations in zooplankton

We studied the effect of zooplankton diet on MeHg accumulation in different zooplankton size-fractions from lakes of different trophic status. Using fatty acid biomarkers, we tested the hypotheses that (a) variations of MeHg concentrations are determined bythe taxonomic composition of zooplankton and (b) concentrations of dietary algal and bacterial compounds can predict MeHg concentrations of seston (10-64 microm), micro- (100-200 microm), meso- (200-500 microm), and macrozooplankton (>500 microm) in lakes on Vancouver Island, Canada. MeHg concentrations increased from seston (4-48 ng g dry weight(-1)) to macrozooplankton (94-240 ng g dry weight(-1)), indicating that MeHg accumulated as a function of plankton size. Results from linear regression analysis showed that MeHg concentrations were not significantly related to the taxonomic composition of zooplankton. However, using dietary lipid biomarkers, we demonstrated that bacterial diet (R2 = 0.50; p < 0.01) could better predict variations of MeHg concentrations in zooplankton than essential algal diet (R2 = 0.35; p < 0.01). Because MeHg accumulation within the planktonic food web was higher (20x) than the observed accumulation of total bacterial (6.5x) and algal (4.7x) diet biomarkers, zooplankton retained dietary MeHg more efficiently than bacterial and algal diet compounds. These results indicate that MeHg of macrozooplankton, the preferred prey size of planktivorous fish, is more efficiently transferred than essential diet compounds to organisms at higher trophic levels.     

Scalable, “Dip‐and‐Dry” Fabrication of a Wide‐Angle Plasmonic Selective Absorber for High‐Efficiency Solar–Thermal Energy Conversion

A galvanic‐displacement‐reaction‐based, room‐temperature “dip‐and‐dry” technique is demonstrated for fabricating selectively solar‐absorbing plasmonic‐nanoparticle‐coated foils (PNFs). The technique, which allows for facile tuning of the PNFs' spectral reflectance to suit different radiative and thermal environments, yields PNFs which exhibit excellent, wide‐angle solar absorptance (0.96 at 15°, to 0.97 at 35°, to 0.79 at 80°), and low hemispherical thermal emittance (0.10) without the aid of antireflection coatings. The thermal emittance is on par with those of notable selective solar absorbers (SSAs) in the literature, while the wide‐angle solar absorptance surpasses those of previously reported SSAs with comparable optical selectivities. In addition, the PNFs show promising mechanical and thermal stabilities at temperatures of up to 200 °C. Along with the performance of the PNFs, the simplicity, inexpensiveness, and environmental friendliness of the “dip‐and‐dry” technique makes it an appealing alternative to current methods for fabricating selective solar absorbers.     

Photoquantum Hall Effect and Light‐Induced Charge Transfer at the Interface of Graphene/InSe Heterostructures

The transfer of electronic charge across the interface of two van der Waals crystals can underpin the operation of a new class of functional devices. Among van der Waals semiconductors, an exciting and rapidly growing development involves the “post‐transition” metal chalcogenide InSe. Here, field effect phototransistors are reported where single layer graphene is capped with n‐type InSe. These device structures combine the photosensitivity of InSe with the unique electrical properties of graphene. It is shown that the light‐induced transfer of charge between InSe and graphene offers an effective method to increase or decrease the carrier density in graphene, causing a change in its resistance that is gate‐controllable and only weakly dependent on temperature. The charge transfer at the InSe/graphene interface is probed by Hall effect and photoconductivity measurmentes and it is demonstrated that light can induce a sign reversal of the quantum Hall voltage and photovoltaic effects in the graphene layer. These findings demonstrate the potential of light‐induced charge transfer in gate‐tunable InSe/graphene phototransistors for optoelectronics and quantum metrology.     

Solid Solubility in Laser Cladding

Laser cladding techniques have recently enjoyed attention in preparing in-situ novel surface clad alloys with extended solid solution. Mass transport involved in this process is rather intriguing since it plays the major role in producing new materials without being restricted by equilibrium phase diagram. Although earlier work has identified convection as the dominant factor for homogeneous liquid metal composition, very little is understood about the solute redistribution at the solid-liquid interface under such non-equilibrium conditions. In this paper, a mathematical model is presented for determining the composition of extended solid solution formed due to rapid cooling in laser cladding. This model considers a diffusion mechanism for mass transport in a one-dimensional semi-infinite molten pool of the cladding material from which heat is removed by conduction through a one-dimensional semi-infinite solid substrate. The rate of solidification was obtained by modeling the cooling process as a composite medium heat transfer problem, and the discontinuity of the concentration field was simulated using a nonequilibrium partition coefficient. A non-similar exact solution for the mass transport equation was obtained using a set of similarity variables derived using Lie group theory.     

Mild sulfonated polyether ketone ether ketone ketone incorporated polysulfone membranes for microbial fuel cell application

To address the impediments of low power generation of Nafion, which is the main hurdle in the commercialization of microbial fuel cells (MFC), the current study focuses on developing a new PEM for MFC from mild sulfonation of PEKEKK with relatively improved physiochemical properties. In this study, mild post sulfonation of a polyether ketone ether ketone ketone (PEKEKK) has been successfully achieved using 98% H2SO4 at 90°C under reflux. 5%–30% (wt%) of sulfonated PEKEKK (SPEKEKK) loaded polysulfone (PSU) composite membranes were fabricated via a solution casting method. Ingeminating evidence of the sulfonation and structure of sulfonated polymer was proved by ¹H NMR peaks integration data and FTIR, respectively. The addition of SPEKEKK to PSU showed significant improvement in conductivity owing to the availability of more protonated sites ( SO3H) and water mediated pathways for the conduction of protons. The composite membrane containing 30 wt% SPEKEKK exhibits the highest conductivity of 0.12 S/cm at 90°C. The water uptakes and swelling ratio of the composite membranes are all higher than that of the pristine PSU membrane and show an increasing trend with increasing SPEKEKK content, thus validating the availability of water domains. Meanwhile, the lowest initial decomposition temperatures assigned to sulfonic acid groups and main chain degradation of the polysulfone/polyether ketone ether ketone ketone (PSU/SPEKEKK) composite membranes occurred at ~300°C and ~500°C respectively, which reflects an excellent thermal stability property. The experimental results indicate that the PSU/SPEKEKK membrane has the potential to greatly enhance the efficiency of MFCs.