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Mechanical and hydraulic properties of carbonate rock:The critical role of porosity

Journal of Rock Mechanics and Geotechnical Engineering 2023年第4期15卷 814-825页

作者： Kam ng J.Carlos Santamarina Department of Civil and Architectural Engineering and Construction Management University of WyomingLaramieWY82071USA Physical Science and Engineering Division King Abdullah University of Science and TechnologyThuwal23955-6900Saudi Arabia

Carbonate rocks are extensively used in civil infrastructure and play a critical role in geoenergy geoengineering,either as hydrocarbon reservoirs or potential repositories for CO_(2)geological *** genesis and diagenetic overprint determine the properties of carbonate *** study combines recent data gathered from Madison Limestone and an extensive dataset compiled from published sources to analyze the hydraulic and mechanical properties of limestone carbonate *** models and data analyses recognize the inherently granular genesis of carbonate rocks and explain the strong dependency of physical properties on *** asymptotically-correct power model in terms of(1-Ф/Ф*)a is a good approximation to global trends of unconfined stiffness E and unconfined compressive strength UCS,cohesive intercept in Mohr-Coulomb failure envelopes,and the brittle-toductile transition *** power model is the analytical solution for the mechanical properties of percolating granular *** adopted a limiting granular porosityФ*=0.5 for all models,which was consistent with the loosest packing of monosize *** fitted power model has exponent(α=2)in agreement with percolation theory and highlights the sensitivity of mechanical properties to *** and models confirm a porosity-independent ratio between unconfined stiffness and strength,and the ratio follows a log-normal distribution with mean(E/UCS)≈*** high angle of internal shear strength measured for carbonate rocks reflects delayed contact failure with increased confinement,and it is not sensitive to *** spans more than six orders of *** size controls pore size and determines the reference permeability k^(*)at the limiting porosityФ*=*** a given grain size from fine to coarse-grained dominant carbonates,permeability is very sensitive to changes in porosity,suggesting preferential changes in the internal pore network during compaction.

关键词： Rock porosity Carbonate permeability Rock unconfined stiffness Unconfined compressive strength(UCS)

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Preconditioned Iterative Methods for Algebraic Systems from Multiplicative Half-Quadratic Regularization Image Restorations

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Numerical Mathematics(Theory,Methods and Applications) 2010年第4期3卷 461-474页

作者： Michael K.ng Department of Mathematics Hong Kong Baptist UniversityKowloon TongHong Kong

Image restoration is often solved by minimizing an energy function consisting of a data-fidelity term and a regularization term.A regularized convex term can usually preserve the image edges well in the restored *** this paper,we consider a class of convex and edge-preserving regularization functions,i.e.,multiplicative half-quadratic regularizations,and we use the Newton method to solve the correspondingly reduced systems of nonlinear *** each Newton iterate,the preconditioned conjugate gradient method,incorporated with a constraint preconditioner,is employed to solve the structured Newton equation that has a symmetric positive definite coefficient matrix. The eigenvalue bounds of the preconditioned matrix are deliberately derived,which can be used to estimate the convergence speed of the preconditioned conjugate gradient *** use experimental results to demonstrate that this new approach is efficient, and the effect of image restoration is reasonably well.

关键词： Edge-preserving image restoration multiplicative half-quadratic regularization Newton method preconditioned conjugate gradient method constraint preconditioner eigenvalue bounds

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Production of rhamnolipids-producing enzymes of Pseudomonas in E. coli and structural characterization

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Frontiers of Chemical Science and Engineering 2017年第1期11卷 133-138页

作者： Kata Kiss Wei Ting ng Qingxin Li Institute of Chemical & Engineering Sciences Agency for Science Technology and Research Jurong Island 627833 Singapore

Rhamnolipids are a class ofbiosurfactants that have a great potential to be used in industries. Five proteins/enzymes, namely RhlA, RhlB, RhlC, RhlG and RhlI, are critical for the production of rhamnolipids in Pseudomonas aeruginosa. Four of the 5 proteins except RhlC were successfully over-expressed in E. coli and three of them （RhlA, RhlB and RhlI） were purified and obtained in milligram quantities. The purified proteins were shown to be folded in solution. Homology models were built for RhlA, RhlB and RhlI. These results lay a basis for further structural and functional characterization of these proteins in vitro to favor the construction of super strains for rhamnolipids production.

关键词： rhamnolipids Pseudomonas RhlA RhlB,RhlI protein folding

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The effect of variable viscosity on the flow and heat transfer of a viscous Agwater and Cu-water nanofluids

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Journal of Hydrodynamics 2013年第1期25卷 1-9页

作者： VAJRAVELU Kuppalapalle PRASAD Kerehalli Vinayaka ng Chiu-On Department of Mathematics University of Central Florida Department of Mathematics VSK University Department of Mechanical Engineering The University of Hong Kong

A numerical study is carried out to study the effects of the temperature dependent viscosity on the flow and heat transfer of a nanofluid over a flat surface in the presence of viscous dissipation. The governing nonlinear partial differential equations are transformed into nonlinear ordinary differential equations, and are solved numerically by the Keller-box method. The numerical results indicate that the effect of nanoparticle volume fraction is to increase the heat transfer and hence enhance the thermal boundary layer thickness. This is true even in the presence of variable viscosity and the viscous dissipation. Furthermore, the results obtained for heat transfer characteristics with nanoparticles reveal many interesting behaviors that warrant further study on the effects of the ＂nano-solid-particles＂.

关键词： nanofluid particles variable viscosity boundary layers viscous dissipation Keller-box method

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Measuring gravitational effect of superintense laser by spin-squeezed Bose-Einstein condensates interferometer

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Chinese Physics B 2022年第5期31卷 265-273页

作者： Eng Boon ng C.H.Raymond Ooi Department of Physics University of MalayaKuala Lumpur 50603Malaysia

We consider an extremely intense laser,enclosed by an atom *** gravitational potential generated from the high-intensity laser is solved from the Einstein field equation under the Newtonian *** compute the strength of the gravitational force and study the feasibility of measuring the force by the atom *** intense laser field from the laser pulse can induce a phase change in the interferometer with Bose-Einstein *** push up the sensitivity limit of the interferometer with Bose-Einstein condensates by spin-squeezing effect and determine the sensitivity gap for measuring the gravitational effect from intense laser by atom interferometer.

关键词： intense laser field atom interferometer Bose-Einstein condensates spin-squeezing

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NUMERICAL SIMULATION OF 3-D DENSE SOLID-LIQUID TWO-PHASE TURBULENT FLOW IN A NON-CLOGGIng MUD PUMP

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Chinese Journal of Mechanical Engineering 2004年第4期17卷 623-627页

作者： YuanShouqi zh.ngPei~ng zh.ngJinfeng XuWeixinq ResearchCenterofFluidMachine~EngineeringandTechnology JiangsuUniversityZhenjiang212013China

A mathematical model is set to evaluate the 3-D dense solid-liquid two-phaseturbulent flow in a non-clogging mud pump, the flow feature in the impeller channel is simulatedwith the tool of IPSA. Meanwhile, resort to TECPLOT as the post-processor, the simulation results isvisualized. The results show the main flow characteristics: There exists backflow and aberrantvelocities at inlet area and a relative velocity slip between two phases; A jet-wake flow pattern isdiscerned around the shroud-suction side area; The relative velocity vector of solid phase iscloser to the pressure surface than that of liquid phase and the trend is more obvious with theincrease of diameter; The kinetic energy of turbulence k and the dissipation rate e reach theirpeaks at the corner of pressure and suction surface. The simulation results show a good agreementwith the experimental flow features in the impeller channel, which prove the turbulent model used isvalid and provide a theoretical design basis to non-clogging pumps.

关键词： Non-clogging pump Two-phase flow Turbulent flow Numerical simulation

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Transdermal drug delivery systems in diabetes management: A review

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Asian Journal of Pharmaceutical Sciences 2020年第1期15卷 13-25页

作者： Li Ching ng Manish Gupta School of Pharmacy Monash University MalaysiaBandar Sunway 47500Malaysia Faculty of Pharmacy DIT UniversityDehradun 248009India

Diabetes mellitus is a chronic disease in which there is an insufficient production of insulin by the pancreas, or the insulin produced is unable to be utilized effectively by the body. Diabetes affects more than 415 million people globally and is estimated to strike about 642 million people in 2040. The WHO reported that diabetes will become the seventh biggest cause of mortality in 2030. Insulin injection and oral hypoglycemic agents remain the primary treatments in diabetes management. These often present with poor patient compliance. However, over the last decade, transdermal systems in diabetes management have gained increasing attention and emerged as a potential hope in diabetes management owing to the advantages that they offer as compared to invasive injection and oral dosage forms. This review presents the recent advances and developments in transdermal research to achieve better diabetes management. Different technologies and approaches have been explored and applied to the transdermal systems to optimize diabetes management. Studies have shown that these transdermal systems demonstrate higher bioavailability compared to oral administration due to the avoidance of first-pass hepatic metabolism and a sustained drug release pattern. Besides that, transdermal systems have the advantage of reducing dosing frequency as drugs are released at a predetermined rate and control blood glucose level over a prolonged time, contributing to better patient compliance. In summary, the transdermal system is a field worth exploring due to its significant advantages over oral route in administration of antidiabetic drugs and biosensing of blood glucose level to ensure better clinical outcomes in diabetes management.

关键词： Transdermal Diabetes Antidiabetic Insulin Drug delivery system

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Protein deacetylases and axonal regeneration

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Neural Regeneration Research 2015年第6期10卷 870-871页

作者： Fanny ng Bor Luen Tang Department of Biochemistry Yong Loo Lin School of MedicineNational University Health System Graduate School for Integrative Sciences and Engineering National University of Singapore

A neuron with injured or severed axon responds with attempts at axonal regrowth. In this regard, axonal regeneration of peripheral nerves occurs far more efficiently compared to central nervous system （CNS） neurons. The latter typically could not form a proper growth cone, and any axonal regeneration in vivo is very limited. The adult CNS environment is not conducive for axonal regrowth. An extensive body of work has revealed mechanisms whereby the myelin-associated inhibitors and extracellular matrix chondroitin sulfate proteoglycans promote collapse of axonal growth cones or repel their advances （Lee and zh.ng, 2012）. The intrinsic axonal regeneration capacity of an injured neuron is, however,

关键词： Protein deacetylases axonal regeneration

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ON ALGORITHMS FOR AUTOMATIC DEBLURRIng FROM A SIngLE IMAGE

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Journal of Computational Mathematics 2012年第1期30卷 80-100页

作者： Wei Wang Michael K.ng Department of Mathematics Tongji UniversityShanghai 200092China Centre for Mathematical Imaging and Vision and Department of Mathematics Hong Kong Baptist UniversityKowloon TongHong KongChina

In this paper, we study two variational blind deblurring models for a single linage,The first model is to use the total variation prior in both image and blur, while the second model is to use the flame based prior in both image and blur. The main contribution of this paper is to show how to employ the generalized cross validation （GCV） method efficiently and automatically to estimate the two regularization parameters associated with the priors in these two blind motion deblurring models. Our experimental results show that the visual quality of restored images by the proposed method is very good, and they are competitive with the tested existing methods. We will also demonstrate the proposed method is also very efficient.

关键词： Blind deconvolution Iterative methods Total variation Framelet Generalizedcross validation.

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Growth performance and scale insect infestation of Shorea leprosula in a common garden experimental plot

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Journal of Forestry Research 2023年第3期34卷 781-792页

作者： Chin Hong ng Kevin Kit Siong ng Soon Leong Lee Rempei Suwa Chai Ting Lee Lee Hong Tnah Forest Research Institute Malaysia 52109 KepongSelangorMalaysia Forestry Division Japan International Research Center for Agricultural SciencesTsukubaIbaraki 305‑8686Japan

Many tree planting programmes have long been initiated to increase forest cover to mitigate the effects of global climate *** planting requires careful planning at the project level,including using suitable species with favourable ***,there is a paucity of improvement data for tropical tree *** experimental common garden of Shorea leprosula was established to study traits related to growth performance which are key factors in planting *** of *** were collected from nine geographical forest *** study the effects of genetic variation,seedlings were planted in a common environment following a randomized complete block *** performance data collected 2017‒2019,one population showed the highest coefficient for relative height growth,significantly higher than most of the other ***,this population from Beserah also exhibited the lowest coefficient for scale insect *** study provides preliminary results on growth performance and susceptibility to scale insect infestation in *** and the first common garden experiment site conducted on dipterocarp *** lays a foundation for future genome-wide studies.

关键词： Root collar diameter Height Scale insect Relative growth rate Dipterocarp

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