Dynamic evolution mechanism of water-bearing coal permeability and water film under stress

To explore coal permeability evolution mechanism under the comprehensive action of multiple factors including stress - adsorption - water and slippage effect, considering the coal deformation induced by stress - adsorption, the expression of water film thickness was corrected to quantitatively characterize the effective pore size, and based on this, the intensity of gas slippage effect of water-bearing coal was further quantified and the permeability model was established under the comprehensive action of multiple factors. Combined with experimental research to verify the reliability of permeability model, and then the evolution mechanism of coal permeability, water film and slippage factors under the comprehensive action of multiple factors was further revealed. The results show that under different water saturation conditions, the permeability decreases sharply first and then tends to flat with the increase of effective stress; under the same effective stress condition, the permeability decreases with the increase of water saturation. The water film thickness changes dynamically under the action of stress - adsorption – water, the water film thickness has a negative correlation with stress and adsorption, but a positive correlation with water saturation; the slippage factor increases gradually with the increase of water saturation, but the increase trend is gentle under low stress condition, and more sharply under high stress condition. In addition, based on the disjoining pressure of gas-liquid-solid surface, the expressions of dynamic water film in square and equilateral triangle under the effect of stress-adsorption were deduced, and the evolution mechanisms of gas permeability, water film and slip coefficient of pores with different geometric shapes are compared and analyzed. Due to the presence of corner holes, the order of water film thickness in pores of different geometric forms is circle > square > equilateral triangle from large to small, the order of permeability is opposite; the slippage factor in circular is larger than that in angular pore, while the slippage factor in square and equilateral triangle pore has little difference

A finite volume numerical approach for coastal ocean circulation studies : comparisons with finite difference models

Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 112 (2007): C03018, doi:10.1029/2006JC003485.An unstructured grid, finite volume, three-dimensional (3-D) primitive equation coastal ocean model (FVCOM) has been developed for the study of coastal ocean and estuarine circulation by Chen et al. (2003a). The finite volume method used in this model combines the advantage of finite element methods for geometric flexibility and finite difference methods for simple discrete computation. Currents, temperature, and salinity are computed using an integral form of the equations, which provides a better representation of the conservative laws for mass, momentum, and heat. Detailed comparisons are presented here of FVCOM simulations with analytical solutions and numerical simulations made with two popular finite difference models (the Princeton Ocean Model and Estuarine and Coastal Ocean Model (ECOM-si)) for the following idealized cases: wind-induced long-surface gravity waves in a circular lake, tidal resonance in rectangular and sector channels, freshwater discharge onto the continental shelf with curved and straight coastlines, and the thermal bottom boundary layer over the slope with steep bottom topography. With a better fit to the curvature of the coastline using unstructured nonoverlapping triangle grid cells, FVCOM provides improved numerical accuracy and correctly captures the physics of tide-, wind-, and buoyancy-induced waves and flows in the coastal ocean. This model is suitable for applications to estuaries, continental shelves, and regional basins that feature complex coastlines and bathymetry.This research was supported by the U.S. GLOBEC Northwest Atlantic/Georges Bank program through NSF grants OCE-0234545, OCE-0227679, NOAA grant NA 160P2323, and NSF CoOP grant OCE-0196543 to C. Chen and NSF OCE-0227679 and the WHOI Smith Chair to R. C. Beardsley. H. Huang and Q. Xu were supported by Chen’s Georgia and South Carolina Sea Grant awards NA06RG0029 and NA960P0113. G. Cowles was supported by the SMAST fishery program through NOAA grants DOC/NOAA/NA04NMF4720332 and DOC/NOAA/NA05NMF4721131

Penyelesaian Tindak Pidana Perjudian yang Dilakukan oleh Anak Menurut UU No.11 Tahun 2012

The title of this legal writing is "The Completion of the Crime of Gambling Carried Out by minors based on the law Number 11 of 2012 on the Juvenile Justice system". This type of research is normative legal research. Normative legal research is a research conducted or focusing on norm of positive law in the form of legislation. Legal issues raised is whether the completion of the crime of gambling by children is in conformity with the law Number 11 of 2012 about the juvenile justice system. The purpose of this research is to determine and analyze the completion of the crime of gambling by children under the law of the juvenile justice system. The result showed that the efforts made to prevent criminal acts of a child is an attempt preventive and repressive efforts. Juvenile justice system is closely related to restorative justice. Regarding the obligation to make a diversion conducted by law enforcement officials, in particular under Article 7 and 96 of the law number 11 of 2012 on the Juvenile Justice System

Location-based services

Location-Based Services (LBS) are mobile applications that provide information depending on the location of the user. To make LBS work, different system components are needed, i.e., mobile devices, positioning, communication networks, and service and content provider. Almost every LBS application needs several key elements to handle the main tasks of positioning, data modeling, and information communication. With the rapid advances in mobile information technologies, LBS have become ubiquitous in our daily lives with many application fields, such as navigation and routing, social networking, entertainment, and healthcare. Several challenges also exist in the domain of LBS, among which privacy is a primary one. This topic introduces the key components and technologies, modeling, communication, applications, and the challenges of LBS

Efficient production of ethylene glycol from cellulose over Co@C catalysts combined with tungstic acid

Catalytic conversion of renewable cellulose, instead of fossil resources, to high-value ethylene glycol (EG) is of great significance for reducing considerable worries regarding the energy problem. However, the EG production from cellulose is dependent on Ni and Ru based catalysts. Herein, encapsulated Co@C catalyst was firstly applied for EG production from cellulose combined with tungstic acid (TA). The mixing of the two catalysts in different ratios was compared and well-controlled, and the highest 67.3% yield of EG can be achieved. TA is used mainly to promote both the cellulose hydrolysis and the retro-aldol reaction of glucose to glycolaldehyde. Co@C catalysts are responsible for the hydrogenation of glycolaldehyde to EG. Compared with traditional noble metals and composite catalysts, the inexpensive and easily synthesized Co@C catalysts could greatly reduce the cost of production of EG. The Co@C catalysts encapsulated with outside graphene layers can keep high stability for at least 6 runs

Production of liquid fuel intermediates from furfural via aldol condensation over Lewis acid zeolite catalysts

Aldol condensation reactions between furfural and acetone can be used to produce liquid fuel intermediates. It was found that tin-containing zeolites with MFI (Sn-MFI) and BEA* (Sn-Beta) framework structures are effective for C-C bond formation via the aldol condensation reactions between furfural and acetone. Aldol condensation between furfural and acetone produced two main products, 4-(2-furyl)-3-buten-2-one (FAc) and 1,5-di-2-furanyl-1,4-pentadien-3-one (F2Ac). Although both these catalysts were active for the aldol condensation reactions, different selectivities to aldol products were observed over Sn-MFI and Sn-Beta. FAc and F2Ac were formed over the Sn-Beta catalyst with selectivities to FAc of 40% and F2Ac of 22%, respectively. In contrast, only FAc was produced over Sn-MFI. The variation in selectivity is likely due to different pore geometries of Sn-Beta and Sn-MFI, suggesting that Sn-MFI exhibits shape selectivity for aldol condensation between furfural and acetone. In addition, it was found that the addition of water to the reaction system can also affect the product selectivity, leading to the aldol product exclusively being FAc over Sn-Beta

Lignin-first depolymerization of native corn stover with an unsupported MoS2 catalyst

The lignin-first biorefinery method appears to be an attractive approach to produce phenolic chemicals. Herein, corn stover was employed for the production of phenolic monomers using an unsupported non-noble MoS2 catalyst. The yield of phenolic monomers was enhanced from 6.65% to 18.47% with MoS2 at 250 degrees C and about 75% lignin was degraded with more than 90% glucan reserved in the solid residues. The Fourier-Transform Infrared (FT-IR) and heteronuclear single quantum coherence-nuclear magnetic resonance (H-1-C-13 HSQC-NMR) characterization suggested that the cleavage of the beta-O-4, gamma-ester and benzyl ether linkages were enhanced, promoting the delignification and the depolymerization of lignin. The catalyst performance was relatively effective with 14.30% phenolic monomer yield after the fifth run. The effects of the reaction temperature, the initial hydrogen pressure, the dosage of catalyst, and the reaction time were investigated. The model reactions were also proposed for the potential mechanism study. This work provides some basic information for the improvement of the graminaceous plant lignin-first process with a non-noble metal catalyst

Dehydration of glucose to 5-hydroxymethylfurfural and 5-ethoxymethylfurfural by combining Lewis and Bronsted acid

In this work, glucose was transformed into 5-hydroxymethylfurfural (HMF) and 5-ethoxymethylfurfural (EMF) in the presence of AlCl3 center dot 6H(2)O and a Bronsted solid acid catalyst (PTSA-POM). GVL (gamma-valerolactone)-water and ethanol-water solvent systems were evaluated in the dehydration reaction of glucose into HMF and EMF, respectively. Water content and dosage of AlCl3 center dot 6H(2)O were examined in the conversion of glucose into HMF, and some valuable chlorides (FeCl3 center dot 6H(2)O, NiCl2 center dot 6H(2)O, CrCl3 center dot 6H(2)O etc.) were also used in contrast with AlCl3 center dot 6H(2)O. Some different organic solvents were added to the ethanol-water system to explore whether it would be beneficial to the generation of EMF. A high yield of HMF (60.7%) was obtained at 140 degrees C within 60 min in GVL-water (10:1) solvent system, and total yield 42.1% of EMF and HMF (30.6% EMF, 11.5% HMF) was achieved at 150 degrees C after 30 min in an ethanol-water (9 : 1) solvent system

Selective Hydrogenolysis of 5-Hydroxymethylfurfural to 2-Hexanol over Au/ZrO2 Catalysts

2-Hexanol (2-HOL) is a versatile biomass-derived platform molecule for synthesis of liquid transportation fuels, lubricants, or detergents. Herein, a one-step preparation of 2-HOL using 5-hydroxymethylfurfural (HMF) as a substrate was reported for the first time. Several Au-based catalysts supported on different metal oxides were prepared to explore the relationship between carrier and catalytic activity. The results showed that the highest 2-HOL yield of 65.8 % was obtained at complete HMF conversion over the 5 %Au/ZrO2 catalyst. The 5 %Au/ZrO2 catalyst exhibited excellent durability after five consecutive recycling runs, while confirming its remarkable ring-opening hydrogenolysis on other biomass-derived furanics, furfural, with a total yield of 1-pentanol and 2-pentanol of 67.4 %. The distinguished ring-opening hydrogenolysis performance of the Au/ZrO2 catalyst originated from a synergistic effect between the interfacial Au-O-Zr oxygen vacancies-induced Lewis acidic sites (activating C-OH/C=O bonds) and metallic Au (activating H-2). This work provides a possibility for producing 2-HOL from HMF with high yield, expanding the sustainable application of lignocellulosic biomass