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Experimental and numerical investigation of Weibullian behavior of grain crushing strength

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Geoscience Frontiers 2020年第2期11卷 401-411页

作者： Quanshui Huang Wei Zhou Gang Ma Tang-Tat ng Kun Xu State Key Laboratory of Water resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China Key Laboratory of rock Mechanics in Hydraulic Structural Engineering Wuhan UniversityMinistry of EducationWuhan 430072China University of New Mexico AlbuquerqueNM87131USA

The Weibullian behavior of single grain crushing strength was investigated experimentally and numerically with the aim of enhancing the understanding of rock grain *** morphologies of pebble grains were obtained using white light 3D laser scanning and image processing.A grain shape library was constructed for grain shape analysis with different shape *** use of the shape library and grain stability analysis is discussed for a suggested procedure to rotate a grain to its most stable *** grain crushing tests were performed for 30 pebbles to obtain force-displacement curves and fracture *** grain was compressed diametrically between flat *** expected,the values of the stress at bulk fracture follow a Weibull distribution.A procedure for generating crushable agglomerates with realistic particle shapes was demonstrated,which was accomplished in the discrete element modeling(DEM)of the single grain crushing *** work presented here is novel in that both the heterogeneous micro-structures and randomly distributed flaws are *** DEM results demonstrate that the proposed modeling approach and calibrated parameters are reliable and can reflect the crushing behavior of rock ***,three parametric studies were presented evaluating the effects of micro-crack density,micro-crack disorder,and grain morphology on the Weibullian behavior of the crushing strength,none of which has previously been thoroughly *** three studies provide a deeper insight into the origin of the Weibullian behavior of single grain crushing strength.

关键词： rock grain Grain crushing test Discrete element modeling 3D scanning technique Grain stability Weibullian behavior

Synthesis and Characterization of Lactone Functional Macromonomers by End Group Deactivation and Their Use in Miktoarm Star Polymer

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Open Journal of Polymer Chemistry 2012年第2期2卷 42-55页

作者： kadir Demirelli Feride Bezgin Faculty of Science Department of ChemistryUniversty of FiratElazigTurkey Faculty of Arts and Sciences Department of ChemistryUniversty of Bitlis ErenBitlisTurkey

Newly designed miktoarm star-shaped copolymers made of poly[(benzyl methacrylate(BMA)-co-(ε-caprolacton)(CL)] and poly[(BMA-b-MMA-b-BMA)-co-ε-caprolacton)(CL)] were synthesized by combining ring-opening polymerization (rOP) of ε-caprolactone (CL) and poly(BMA) five membered lacton fuctionalized prepared via atom transfer radical polymerization (ATrP) of BMA, and ε-CL and P(BMA-b-MMA-b-BMA) dual functionalized diblock copolymer, in the presence of tin(II) bis(2-ethylhexanoate) (Sn(Oct)2). Although lactone ended poly(benzyl methacrylate) with ε-caprolactone monomer gave ring open polymerization by Sn(Oct)2, the macromonomer itself did not give any poly- merization The macromonomers, and the miktoarm star-shaped copolymers were analyzed by FT-Ir and 1H-NMr spectroscopies and GPC (gel permeation chromatograph), Differential scanning calorimetry (DSC-50) and termo- gravimetric analysis (TGA-50). These copolymers exhibited the expected structure. The crystallization of star-shaped copolymers was studied by DSC. The results show that when the content of the BMA block increased, the Tm of the star-shaped block copolymer increased.

关键词： Miktoarm Star Polymer Lacton ring Open Polymerization

Implementation of Efficient B2G and V2G in Practical Cases

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Journal of Electronic Science and Technology 2018年第4期16卷 325-340页

作者： MD Shahrukh Adnan Khan Kazi Mahtab kadir Md.Ibrahim Ibne Alam Md.Khairul Alam Jianhui Wong Aseef Iqbal University of Asia Pacific Dhaka 1205 Bangladesh Department of Electrical and Electronic Engineering Universiti Tunku Abdul Rahman Kampar 31900Malaysia Chittagong Independent University Chittagong Bangladesh

In this paper, building to grid(B2G) and vehicle to grid(V2G) have been defined with clear and practical understanding. Both of them are new generation technologies which are the essential part of smart city living and crowd energy clustering. Firstly, an in-detailed overview has been provided with an introduction to B2G and V2G followed by a historical overview and theoretical analysis in respect to smart city planning. Next, a review is conducted on current and previous smart living research, which deals with B2G and V2G. Efficient B2G and V2G implementations in practical cases then have been discussed. Lastly, both of these technical prospects have been analyzed in crowd energy diagram.

关键词： Building to grid(B2G) crowd energy practical implementation smart city living vehicle to grid(V2G)

Thermodynamic Characterization of Planar Shapes and Curves, and the Query of Temperature in Black Holes

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Journal of Applied Mathematics and Physics 2021年第8期9卷 2004-2037页

作者： Güngö r Gündüz Orta Doğ u Teknik Ü niversitesi Ankara Turkey

The purpose of this research is to characterize shapes in thermodynamic terms, namely, in terms of total energy, dissipative energy, entropy, and temperature. As case studies, polygons and some well-known curves were taken, and they were characterized using physical terms. The relation between entropy and curvature was elucidated, and the black hole surface gravity and temperature were criticized and reinterpreted from this point of view. Particular energy attributions were evaluated by comparing the position of any edge of a polygon (i.e. its angle with the horizontal axis) with a broken crystal surface. Energies of all edges were added up at all positions between 0˚ - 360˚. In regular polygons, the total energy decreases with the increase of the number of edges. Entropy increases in the reverse order, and the increase of the number of edges increases entropy. It implies that the circle has the lowest energy but the highest surface entropy. In curves (circle, sine-curve, spiral, and exponential curve), the total energy, dissipative energy, and entropy all depend on amplitude and also on specific variables. Black hole entropy expressed in terms of the surface area is a configurational entropy and not thermal entropy;therefore, it does not involve a varying temperature term. The surface gravity of a black hole is connected to acceleration and thus to curvature. To relate it with the temperature needs to be reinterpreted, because, surface gravity behaves like an attractive force not exactly like temperature. Hawking radiation is still possible, but the black hole does not get warmer as it evaporates. Material loss from the black hole gets faster as its radius decreases due to the curvature effect, i.e. by a mechanism similar to the Gibbs-Thomson effect.

关键词： Polygons Curves Viscoelasticity Energy Entropy Temperature Black Hole

Can a Government Initiate Enterprise reform to Improve Efficiency？ A Cross-Section Analysis of the Chinese Pharmaceutical Industry

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Frontiers of Economics in China-Selected Publications from Chinese Universities 2017年第4期12卷 607-634页

作者： Ying Chu ng Suthathip Yaisawarng Department of Economics Hong Kong Baptist University Hong Kong~ China Department of Economics Union College Schenectady NY 12308-2311 USA

This paper examines the privatization, implemented by the effects of state-owned enterprises （SOE） Chinese government in the 1990s, on enterprise efficiency for a sample of non-privatized SOEs and privatized ex-SOEs. The study calculates input-oriented DEA meta-frontier efficiency scores, after accounting for heterogeneity in technology across groups. These scores are used to test whether or not one group＇s technology dominates the other. A measure of additional input saving is also provided if these enterprises have access to unrestricted rneta-technology. The analysis of the Chinese pharmaceutical industry reveals that privatization has not improved enterprise efficiency, at least in the short run. Almost 56% of inputs could be proportionally saved if these privatized ex-SOEs had been efficient, relative to the recta-production technology while non-privatized SOEs could proportionally save only 51%. Privatized ex-SOEs had less ability to access to meta-technology. This finding could be explained by subsequent observations that China, at the time of our analysis, did not have well-established intellectual property rights and formal drug approval procedures; these two factors are important driving forces for developing joint ventures with foreign investors to gain additional capital funding and technology transfer. Broadly speaking, our results are consistent with the subsequent shakeup in the Chinese pharmaceutical industry.

关键词： privatization DEA managerial efficiency heterogeneous technology Chinese pharmaceutical enterprises

ranking parameters in urban energy models for various building forms and climates using sensitivity analysis

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Building Simulation 2023年第9期16卷 1587-1600页

作者： Aysegul Demir Dilsiz Kaitlynn ng Jérôme Kämpf Zoltan Nagy Department of Civil and Architectural Engineering and Construction Management University of WyomingLaramie WYUSA Intelligent Environments Lab Department of CivilArchitectural and Environmental EngineeringThe University of Texas at AustinAustin TXUSA Energy Informatics Group Idiap Research Institute1920 MartignySwitzerland

Urban Building Energy Modelling(UBEM)allows us to simulate buildings’energy performances at a larger ***,creating a reliable urban-scale energy model of new or existing urban areas can be difficult since the model requires overly detailed input data,which is not necessarily publicly *** calibration is a necessary step to reduce the uncertainties and simulation results in order to develop a reliable and accurate *** to the concerns over computational resources and the time needed for calibration,a sensitivity analysis is often required to identify the key parameters with the most substantial impact before the calibration is deployed in ***,we study the sensitivity of uncertain input parameters that affect the annual heating and cooling energy demand by employing an urban-scale energy model,*** goal is to determine the relative influence of each set of input parameters and their interactions on heating and cooling loads for various building forms under different ***,we conduct a global sensitivity analysis for annual cooling and heating consumption under different climate *** upon this,we investigate the changes in input sensitivity to different building forms,focusing on the indices with the largest Total-order ***,we determine First-order indices and Total-order effects of each input parameter included in the urban building energy *** also provide tables,showing the important parameters on the annual cooling and heating demand for each climate and each building *** find that if the desired calibration process require to decrease the number of the inputs to save the computational time and cost,calibrating 5 parameters;temperature set-point,infiltration rate,floor U-value,*** U-value and roof U-value would impact the results over 55%for any climate and any building form.

关键词： global sensitivity analysis Sobol’method urban energy modeling building stocks energy modelling parameter screening Sobol’indices sustainable urban planning

Occurrence and Distribution of Antifouling Biocide Diuron along the Coastal Areas of Zanzibar Island

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Journal of Geoscience and Environment Protection 2025年第1期13卷 1-17页

作者： Hassan r. Ali Fatma Kh. Ali Miza A. Kombo School of Natural and Social Sciences The State University of Zanzibar Zanzibar Tanzania Tropical research Centre for Oceanography Environment and Natural Resources The State University of Zanzibar Zanzibar Tanzania Karume Institute of Science and Technology Mbweni Zanzibar Tanzania

Diuron (N-(3,4-dichlorophenyl)-N,N-dimethylurea) is one among the booster biocides substituted tributyltin as an antifouling agent. It has continued to be used ever since, though little is known about their levels in the maritime setting of Zanzibar. This paper details the occurrence and distribution of diuron around the coastline of Zanzibar Island. The reported concentrations of diuron in water ranged from Below Detection Limit to 1321.67 ± 52.3 ng/L at Bwawani. Majority of the sites showed levels above Environmental risk Limit of 430 ng/L as proposed by the Dutch Authorities. The findings suggest the contamination is elevated especial in Harbor, Bwawani, Chapwani and even at Marine Protected Areas such Mnemba Island where the value of 620.33 ± 5.70 ng/L was recorded. The main possible sources of the contamination are cargo shipping, passenger speedboats, fishing, and tourism activities taking places in these areas. Therefore, future studies on the antifouling biocide diuron particularly on long term monitoring, chronic exposure, risk assessment, organisms’ responses and pollution models will add special value towards better understanding of the mechanisms and sustainable marine ecosystem health.

关键词： Diuron Coral reefs Harbor Marine resources Marine Protected Areas

A review on 2D MoS_(2) cocatalysts in photocatalytic H_(2) production

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Journal of Materials Science & Technology 2020年第21期56卷 89-121页

作者： Zizhan Liang rongchen Shen Yun Hau ng Peng Zhang Quanjun Xiang Xin Li Key Laboratory of Energy Plants resource and Utilization Ministry of Agriculture and Rural AffairsCollege of Forestry and Landscape ArchitectureSouth China Agricultural UniversityGuangzhou510642China School of Energy and Environment City University of Hong KongHong KongChina State Center for International Cooperation on Designer Low-Carbon&Environmental Materials(CDLCEM) School of Materials Science and EngineeringZhengzhou UniversityZhengzhou450001China State Key Laboratory of Electronic Thin Film and Integrated Devices University of Electronic Science and Technology of ChinaChengdu610054China

Owing to their unique physicochemical,optical and electrical properties,two-dimensional(2D)MoS_(2) cocatalysts have been widely applied in designing and developing highly efficient composite photocatalysts for hydrogen generation under suitable light *** this review,we first elaborated on the fundamental aspects of 2D MoS_(2) cocatalysts to include the structural design principles,synthesis strategies,strengths and ***,we thoroughly highlighted and discussed the modification strategies of 2D MoS_(2) H2-evolution cocatalysts,including doping heteroatoms(***,non-metals,and co-doping),designing interfacial coupling morphologies,controlling the physical properties(***,size,structural defects or pores),exposing the reactive facets or edge sites,constructing cocatalyst heterojunctions,engineering the interfacial bonds and confinement *** the future,the forefront challenges in understanding and in precise controlling of the active sites at molecular level or atomic level should be carefully studied,while various potential mechanisms of photogenerated-electrons interactions should be *** applications of MoS_(2) cocatalyst in the overall water splitting are also *** review may offer new inspiration for designing and constructing novel and efficient MoS_(2)-based composite photocatalysts for highly efficient photocatalytic hydrogen evolution.

关键词： 2D MoS2 cocatalysts Photocatalytic H2 production Heteroatom doping Cocatalyst heterojunctions Charge dynamics

You shall never walk alone:burnout and depression amongst healthcare professionals

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Hepatobiliary Surgery and Nutrition 2021年第5期10卷 678-681页

作者： Kelvin Lin Chieh ng Chen Liu Institute of Mental Health SingaporeSingapore United Family Hospital BeijingChina

There are two stages of tsunami,first is the earthquake in deep sea,followed by *** are three waves of pandemic,the death toll,economic and social disruption,and a psychological storm that is looming in the distance *** this time of worldwide COVID-19 pandemic,to date,we have seen over 200 million cases worldwide,and the death toll is in excess of 4 million,and there are various news reports coming in about devastating economic and social ***,numerous studies report that the public,as well as the healthcare professionals are at heightened risk mental health problems in the short and longer term from pandemic.

关键词： storm earthquake alone