检索结果-南通市图书馆

Species delimitation in the White-faced Cuckoo-dove(Turacoena manadensis) based on bioacoustic data

在线全文

学校读者我要写书评

暂无评论

Chinese Birds 2016年第1期7卷 40-47页

作者： Nathaniel S.R.ng Frank e.Rheindt Department of Biological Sciences National University of Singapore

Background: The White-faced Cuckoo-dove(Turacoena manadensis) is a poorly-known Wallacean endemic with a limited distribution on Sulawesi and its satellites, including the Togian, Banggai and Sula archipelagoes. In 1900, populations from the Sula archipelago were awarded subspecies status T. manadensis sulaensis based on smaller size and minor differences in plumage; however, this distinction has not been corroborated subsequently, and T. manadensis is considered by most modern sources to be monotypic across its ***: We conducted vocal analysis of the cuckoo-doves' main song using recordings collected from across the taxon's natural range. Descriptive information on the songs was obtained from the recordings using bioacoustic analysis software, after which several statistical methods were used to investigate differences in vocalizations among ***: We report deep bioacoustic divergences in vocal trait pattern from across the cuckoo-doves' range, with birds from Peleng and Taliabu in the east having a different vocal trait pattern from birds from Sulawesi, Buton, and Togian in the west. These patterns agree with changes in landmass that accompanied the sea level fluctuations caused by Pleistocene glacial cycles, and indicate that eastern and western cuckoo-dove populations are at the level of different biological ***: We propose that the eastern taxon be elevated to species level as T. sulaensis. Given the rampant degree of habitat destruction in its limited range, this taxonomic change will have important implications on the conservation status of T. sulaensis.

关键词： Wallacea Sulawesi Peleng Taliabu Buton Pleistocene Island biogeography

Interaction of oblique waves with an array of long horizontal circular cylinders

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2007年第4期50卷 490-509页

作者： ng Chiu-On Department of Mechanical engineering the University of Hong Kong Pokfulam Road Hong Kong China

The scattering and radiations of linear oblique waves by multiple long horizontal circular cylinders submerged in water of finite depth are investigated using the multipole expansion method. Analytical expressions for the diffracted and radiated potentials are given as a linear combination of infinite multipoles. The unknown coefficients in the expressions are determined by using the addition theorem of the Bessel function and the cylinder boundary conditions. Also analytical expressions for wave forces, hydrodynamic coefficients and reflection and transmission coeffi-cients are derived. The present analytical solution is verified through the boundary element method and applied to investigate three different cases of the interaction of oblique waves with multiple submerged horizontal circular cylinders. The results show that the number of cylinders, the arrangement and spacing between cylinders play an important role in wave forces, hydrodynamic coefficients and reflection and transmission coefficients. Some interesting and important phenomena are ob-served in numerical experiments.

关键词： scattering and radiation water waves analytical technique hydrodynamic characteristics

Nonlinear dynamical characteristics of bed load motion

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2006年第3期49卷 365-384页

作者： Chiu-On ng Department of Mechanical engineering the University of Hong Kong Hong Kong China

Bed forms of various kinds that evolve naturally on the bottom of sandy coasts and rivers are a result of the kinematics of bed load transport. Based on the group motion of particles in the bed load within the bottom layer, a study on the nonlinear dy- namics of bed load transport is presented in this paper. It is found that some development stages, such as the initiation, the equilibrium sediment transport, and the transition from a smooth bed to sand dunes, can be accounted for by different states in the nonlinear sys- tem of the bed load transport. It is verified by comparison with experimental data reported by Laboratoire Nationae D’Hydraulique, Chatou, France, that the evolution from a smooth bed to sand dunes is determined by mutation in the bed load transport. This paper pre- sents results that may offer theoretical explanations to the experimental observations. It is also an attempt to apply the state-of-the-art nonlinear science to the classical sediment transport mechanics.

关键词： bed load, bed form, nonlinear dynamics.

Incorporation of a nanotechnology-based additive in cementitious products for clay stabilisation

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical engineering 2020年第5期12卷 1056-1069页

作者： e.U.eyo S.ng’ambi S.J.Abbey School of energy Construction and EnvironmentFaculty of EngineeringEnvironment and ComputingCoventry UniversityCoventryUK Faculty of environment and Technology Department of Geography and Environmental ManagementCivil Engineering ClusterUniversity of the West of EnglandBristolUK

The mechanical performances and water retention characteristics of clays,stabilised by partial substitution of cement with by-products and inclusion of a nanotechnology-based additive called RoadCem(RC),are studied in this *** unconfined compression tests and one-dimensional oedometer swelling were performed after 7 d of curing to understand the influence of addition of 1%of RC material in the stabilised soils with the cement partially replaced by 49%,59%and 69%of ground granulated blast furnace slag(GBBS)or pulverised fuel ash(PFA).The moisture retention capacity of the stabilised clays was also explored using the soil-water retention curve(SWRC)from the measured *** confirmed an obvious effect of the use of RC with the obtained strength and swell properties of the stabilised clays suitable for road application at 50%replacement of *** outcome is associated with the in-depth and penetrating hydration of the cementitious materials by the RC and water which results in the production of needle-like matrix with interlocking filaments e a phenomenon referred to as the‘wrapping’*** the other hand,the SWRC used to describe the water holding capacity and corresponding swell mechanism of clays stabilised by a proportion of RC showed a satisfactory *** moisture retention of the RC-modified clays was initially higher but reduced subsequently as the saturation level increased with decreasing *** phenomenon confirmed that clays stabilised by including the RC are water-proof in nature,thus ensuring reduced porosity and suction even at reduced water ***,the stabilised clays with the combination of cement,GGBS and RC showed a better performance compared to those with the PFA included.

关键词： Cement Ground granulated blast furnace slag(GBBS) Fly ash RoadCem(RC) Swell Stabilisation Unconfined compressive strength Soil-water retention curve(SWRC)

Rotating electroosmotic flow of an eyring fluid

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2017年第2期33卷 295-315页

作者： Cheng Qi Chiu-On ng Department of Mechanical engineering The University of Hong Kong Hong Kong China

A perturbation analysis is presented in this paper for the electroosmotic (eO) flow of an eyring fluid through a wide rectangular microchannel that rotates about an axis perpendicular to its own. Mildly shear-thinning rheology is assumed such that at the leading order the problem reduces to that of Newtonian eO flow in a rotating channel, while the shear thinning effect shows up in a higher-order problem. Using the relaxation time as the small ordering parameter, analytical solutions are deduced for the leading- as well as first-order problems in terms of the dimensionless Debye and rotation parameters. The velocity profiles of the ekman-electric double layer (eDL) layer, which is the boundary layer that arises when the ekman layer and the eDL are comparably thin, are also deduced for an eyring fluid. It is shown that the present perturbation model can yield results that are close to the exact solutions even when the ordering parameter is as large as order unity. By this order of the relaxation time parameter, the enhancing effect on the rotating eO flow due to shear-thinning eyring rheology can be significant.

关键词： electroosmotic flow eyring fluid Rotating channel

FCC coprocessing oil sands heavy gas oil and canola oil. 3. Some cracking characteristics

在线全文

学校读者我要写书评

暂无评论

Green energy & environment 2019年第1期4卷 83-91页

作者： Siauw H.ng Nicole e.Heshka Ying Zheng Qiang Wei Fuchen Ding Natural Resources Canada CanmetENERGY Department of Chemical engineering University of New Brunswick State Key Laboratory of Heavy Oil Processing China University of Petroleum Beijing Institute of Petrochemical Technology

Coprocessing of bitumen-derived feeds and biomass through a fluid catalytic cracking(FCC) route has the potential to assist in the reduction of fuel and petroleum product carbon footprints while meeting government regulatory requirements on renewable transportation fuels. This approach is desirable because green house gas(GHG) emissions for producing renewable biofuels are significantly lower than those for fossil fuels, and coprocessing can be executed using existing refining infrastructure to save capital cost. The present study investigates the specific FCC performances of pure heavy gas oil(HGO) derived from oil sands synthetic crude, and a mixture of 15 v% canola oil in HGO using a commercial equilibrium catalyst under typical FCC conditions. Cracking experiments were performed using a bench-scale Advanced Cracking evaluation(ACe) unit at fixed weight hourly space velocity(WHSV) of 8 h^(-1), 490–530℃, and catalyst/oil ratios of 4–12 g/g. This work focuses on some cracking phenomena resulting from the presence of oxygen in the blendda lower heat requirement for cracking due to the exothermic water formation, which also entails lower hydrogen yield at a given severity. The distribution of feed oxygen in gaseous and liquid products, the mitigation in GHG emissions, and the technological and economical advantages of the coprocessing option are also discussed.

关键词： FCC coprocessing Microactivity test(MAT) unit Four-lump kinetic model Heat of formation of water vapour Carbon footprint reduction

On the time development of dispersion in electroosmotic flow througha rectangular channel

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2012年第3期28卷 631-643页

作者： Suvadip Paul Chiu-On ng Department of Mechanical engineering The University of Hong Kong

This is an analytical study on the time develop- ment of hydrodynamic dispersion of an inert species in elec- troosmotic flow through a rectangular channel. The objec- tive is to determine how the channel side walls may affect the dispersion coefficient at different instants of time. To this end, the generalized dispersion model, which is valid for short and long times, is employed in the present study. An- alytical expressions are derived for the convection and dis- persion coefficients as functions of time, the aspect ratio of the channel, and the Debye-Htickel parameter representing the thickness of the electric double layer. For transport in a channel of large aspect ratio, the dispersion may undergo several stages of transience. The initial, fast time develop- ment is controlled by molecular diffusion across the narrow channel height, while the later, slower time development is governed by diffusion across the wider channel breadth. For a sufficiently large aspect ratio, there can be an interlude between these two periods during which the coefficient is nearly steady, signifying the resemblance of the transport to that in a parallel-plate channel. Given a sufficiently long time, the dispersion coefficient will reach a fully-developed steady value that may be several times higher than that with- out the side wall effects. The time scales for these periods of transience are identified in this paper.

关键词： Taylor dispersion. electroosmotic flow. Gener-alized dispersion model

Indexing Non-merohedrally Twinned Crystals by Bruker'sAPeX2 and Agilent's CrysAlis^(PRO), an example of a Crystal Structure That Can Be Refined through either the PLATONRoute or the ‘HKLF 5' Route, and, Simultaneous Data Collection of Two Crystals in a Two-in-one Run

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2014年第2期33卷 294-303页

作者： ng Seik Weng Department of Chemistry University of Malaya 50603 Kuala Lumpur Malaysia Chemistry Department King Abdulaziz University

The first part of this report describes the data reduction of non-merohedrally twinned crystals measured on Bruker and Agilent area-detector diffractometers. The image frames of methyl-2-aminopyrazine-3-carboxylate were processed with APeX2 to furnish a set of overlapping diffraction indices that were used for solution and refinement. CrysAlisPRO was used for processing the frames of bis（diethyldicarbamato）nickel, which exists in monoclinic and tetragonal polymorphs, and in untwinned and twinned forms. In the second part, the crystal structure of [（3-formyl-4- hydroxyphenyl）methyl]triphenylphosphanium chloride was refined through the ‘HKLF 5＇（based on a combined set of diffraction indices） and PLATON（based on one set of diffraction indices） routes to give identical outcomes because the amount of overlap of the twin domains is small. For the third part, in a proof-of-concept investigation, the diffraction pattern of untwinned and twinned 4-{（e）-（4-aminophenyl）diazenyl]phenylamine was recorded simultaneously in one run; the three domains could be indexed and the crystal structure satisfactorily refined. The refinement was identical to those derived from independent measurements; the crystal structure features two independent centrosymmetric molecules, one of which is ordered and the other whole-molecule-disordered. This two-in-one run opens up the possibility that two or more crystals having different atomic compositions can be measured simultaneously if their reciprocal lattices do not overlap significantly.

关键词： merohedral non-merohedral twin APeX2 Crys Alis^PRO two-in-one data collection

WAVe INDUCeD OSCILLATORY AND STeADY FLOWS IN THe ANNULUS OF A CATHeTeRIZeD VISCOeLASTIC TUBe

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2010年第5期22卷 605-617页

作者： ng Chiu-On CHAng Yin-Yee Department of Mechanical engineering The University of Hong Kong

A perturbation analysis based on equations of motion in Lagrangian form is presented for the oscillatory and time-mean viscous flows induced by a propagating wave of small amplitude in an annulus with a viscoelastic outer wall. Owing to the steady streaming effect, the existence of a catheter in a blood vessel brings in an additional steady pressure gradient, a correction to that predicted by the linear theory, and an additional steady shear stress, which may increase the possibility of hemolysis of red blood cells.

关键词： annulus flow steady streaming catheterized artery