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A spatiotemporal analysis of the impact of lockdown and coronavirus on London’s bicycle hire scheme:from response to recovery to a new normal

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Geo-Spatial Information Science 2023年第4期26卷 664-684页

作者： Xiaowei Gao Huanfa Chen james Haworth SpaceTimelab Department of CivilEnvironmental and Geomatic EngineeringUniversity College LondonLondonUnited Kingdom Centre for Advanced Spatial Analysis University College LondonLondonUnited Kingdom

The coronavirus pandemic that started in 2019 has had wide-ranging impacts on many aspects of people’s daily *** the peak of the outbreak,lockdown measures and social distancing changed the ways in which cities *** particular,they had profound impacts on urban transportation systems,with public transport being shut down in many *** share systems(BSS)were widely reported as having experienced an increase in demand during the early stages of the pandemic before returning to pre-pandemic ***,the studies published to date focus mainly on the first year of the pandemic,when various waves saw continual relaxing and reintroductions of ***,they fall short of exploring the role of BSS as we move to the post-pandemic *** address this gap,this study uses origin-destination(O-D)flow data from London’s Santander Cycle Hire Scheme from 2019-2021 to analyze the changing use of BSS throughout the first two years of the pandemic,from lockdown to recovery.A Gaussian mixture model(GMM)is used to cluster 2019 BSS trips into three distinct clusters based on their duration and *** clusters are used as a reference from which to measure spatial and temporal change in 2020 and *** agreement with previous research,BSS usage was found to have declined by nearly 30%during the first *** then saw a sharp increase as restrictions were lifted,characterized by longer,less direct trips throughout the afternoon rather than typical peak commuting *** the aggregate number of BSS trips appeared to return to normal by October 2020,this was against the backdrop of continuing restrictions on international travel and work from home *** period between July and December 2021 was the first period that all government restrictions were *** this time,BSS trips reached higher levels than in ***-temporal analysis indicates a shift away from the traditional morning and evening peak to a more diffuse p

关键词： COVID-19 micro-mobility restrictive measures bicycle share system

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Vertebrate pesticide risk assessment by indigenous communities in New Zealand

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Integrative Zoology 2010年第1期5卷 37-43页

作者： Shaun C.OGILVIE james M.ATARIA james WAIWAI james DOHERTY Aroha MILLER james G.ROSS Charles T.EASON Ecology Department Lincoln UniversityLincolnCanterburyNew Zealand Landcare Research LincolnCanterburyNew Zealand Lake Waikaremoana Hapu Restoration Trust TuaiNew Zealand Tuhoe Tuawhenua Trust MuruparaNew Zealand

In New Zealand,the vertebrate pesticide sodium fluoroacetate(Compound 1080)is aerially applied in baits for control of the brush-tailed possum Trichosurus vulpecula(Kerr,1792).Maori,the indigenous people of New Zealand,have raised concerns about 1080 impacts on culturally-important ***,we outline two steps taken to help Maori assess 1080 ***,field research was undertaken to determine if naturally-occurring plants utilized by a Maori community for food and medicine would take up 1080 from *** baits were placed at the base of individual plants of two species,pikopiko(Asplenium bulbiferum)and karamuramu(Coprosma robusta).Plants were sampled at various times up to 56 days,and samples were analyzed for 1080 *** 1080 was detected in any of the pikopiko samples,whereas 1080 was detected in karamuramu,at a maximum concentration of 5 ppb after seven days,and 2.5 ppb after 14 *** concentration decreased to 0 at 28 days,indicating that 1080 was not *** results of the present study suggest there is negligible risk of humans being poisoned by consum-ing plants that have taken up 1080 from *** allay community concerns that minute concentrations of 1080 might influence the medicinal properties of plants,it is suggested that a withholding period of 30 days after 1080 control operations could be ***,after further consultation we undertook a review of the scientific literature relating to 1080 impacts on additional non-target species of cultural importance to *** information was presented on an interactive foodweb database that allowed the collection and presentation of a large volume of complex information about 1080 in a holistic and pictorial *** database was presented to many Maori communities throughout New Zealand,and feedback was overwhelmingly *** database is likely to play a key role in informing these communities about 1080,and is seen as an important new tool to help these communities

关键词： 1080 indigenous communities Maori risk assessment sodium fluoroacetate

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Atmospheric Precursors of and Response to Anomalous Arctic Sea Ice in CMIP5 Models

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Advances in Atmospheric Sciences 2018年第1期35卷 27-37页

作者： Michael KELLEHER james SCREEN College of Engineering Mathematics and Physical SciencesUniversity of Exeter

This study examines pre-industrial control simulations from CMIP5 climate models in an effort to better understand the complex relationships between Arctic sea ice and the stratosphere, and between Arctic sea ice and cold winter temperatures over Eurasia. We present normalized regressions of Arctic sea-ice area against several atmospheric variables at extended lead and lag times. Statistically significant regressions are found at leads and lags, suggesting both atmospheric precursors of, and responses to, low sea ice; but generally, the regressions are stronger when the atmosphere leads sea ice, including a weaker polar stratospheric vortex indicated by positive polar cap height anomalies. Significant positive midlatitude eddy heat flux anomalies are also found to precede low sea ice. We argue that low sea ice and raised polar cap height are both a response to this enhanced midlatitude eddy heat flux. The so-called "warm Arctic, cold continents" anomaly pattern is present one to two months before low sea ice, but is absent in the months following low sea ice, suggesting that the Eurasian cooling and low sea ice are driven by similar processes. Lastly, our results suggest a dependence on the geographic region of low sea ice, with low Barents–Kara Sea ice correlated with a weakened polar stratospheric vortex, whilst low Sea of Okhotsk ice is correlated with a strengthened polar vortex. Overall, the results support a notion that the sea ice, polar stratospheric vortex and Eurasian surface temperatures collectively respond to large-scale changes in tropospheric circulation.

关键词： sea ice–atmosphere coupling stratosphere–troposphere coupling atmospheric circulation Eurasian climate

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Employing incomplete complex modes for model updating and damage detection of damped structures

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Science China(Technological Sciences) 2008年第12期51卷 2244-2258页

作者： HU Sau-Lon james Department of Ocean Engineering University of Rhode Island

In the study of finite element model updating or damage detection,most papers are devoted to undamped ***,their objective has been exclusively restricted to the correction of the mass and stiffness *** contrast,this paper performs the model updating and damage detection for damped structures.A theoretical contribution of this paper is to extend the cross-model cross-mode(CMCM) method to simultaneously update the mass,damping and stiffness matrices of a finite element model when only few spatially incomplete,complex-valued modes are *** studies are conducted for a 30-DOF(degree-of-freedom) cantilever beam with multiple damaged elements,as the measured modes are synthesized from finite element *** numerical results reveal that applying the CMCM method,together with an iterative Guyan reduction scheme,can yield good damage detection in *** the measured modes utilized in the CMCM method are corrupted with irregular errors,assessing damage at the location that possesses larger modal strain energy is less sensitive to the corrupted modes.

关键词： incomplete complex modes model updating damage detection CMCM damped structures

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WEAKLY COMPRESSIBLE TWO-PRESSURE TWO-PHASE FLOW

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Acta Mathematica Scientia 2009年第6期29卷 1497-1540页

作者： Hyeonseong Jin james Glimm Department of Mathematics Jeju National University Jeju 690-756 Republic of Korea Department of Applied Mathematics and Statistics Stony Brook University Stony Brook NY 11794-3600 Computational Science Center Brookhaven National Laboratory Upton NY 11793-6000 USA

We analyze the limiting behavior of a compressible two-pressure two-phase flow model as the Mach number tends to zero. Formal asymptotic expansions are derived for the solutions of compressible two-phase equations. Expansion coefficients through sec- ond order are evaluated in closed form. Underdetermination of incompressible pressures is resolved by information supplied from the weakly compressible theory. The incompressible pressures are uniquely specified by certain details of the compressible fluids from which they are derived as a limit. This aspect of two phase flow in the incompressible limit appears to be new, and results basically from closures which satisfy single phase boundary conditions at the edges of the mixing zone.

关键词： multiphase flow asymptotic analysis turbulence perturbation

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Gas sorption and non-Darcy flow in shale reservoirs

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Petroleum Science 2017年第4期14卷 746-754页

作者： Xiukun Wang james Sheng Department of Petroleum Engineering Texas Tech UniversityPO Box 43111LubbockTX 79409USA

Gas sorption and non-Darcy flow are two important issues for shale gas reservoirs. The sorption consists of dissolution and adsorption. Dissolved gas and adsorbed gas are different. The former is dissolved in the shale matrix, while the latter is concentrated near the solid walls of pores. In this paper, the Langmuir equation is used to describe adsorption and Henry’s law is used to describe dissolution. The K coefficient in Henry’s law of 0.052 mmol/(MPa g TOC) is obtained by matching experimental data. The amount of dissolved gas increases linearly when pressure increases. Using only the Langmuir equation without considering dissolution can lead to a significant underestimation of the amount of sorbed gas in shales. For non-Darcy gas flow, the apparent permeability model for free gas is established by combining slip flow and Knudsen flow. For adsorbed gas, the surface diffusion effect is also considered in this model. The surface diffu- sion coefficient is suggested to be of the same scale as the gas self-diffusion coefficient, and the corresponding effective permeability is derived. When 1/ increases,k/ kincreases, but the relationship is not linear as the Klinkenberg effect suggests. The effect of adsorption on the gas flow is significant in nanopores (r≤2 nm). Adsorption increases apparent permeability in shales at low pressures and decreases it at high pressures.

关键词： Apparent gas permeability Shale Adsorbed gas Dissolved gas Surface diffusion

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Enhancing PIV image and fractal descriptor for velocity and shear stresses propagation around a circular pier

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Geoscience Frontiers 2017年第4期8卷 869-883页

作者： Alireza Keshavarzi james Ball Water Department Shiraz University School of Civil and Environmental Engineering University of Technology Sydney

In this study,the fractal dimensions of velocity fluctuations and the Reynolds shear stresses propagation for flow around a circular bridge pier are *** the study reported herein,the fractal dimension of velocity fluctuations（u′,v′,w′） and the Reynolds shear stresses（u′v′ and u′w′） of flow around a bridge pier were computed using a Fractal Interpolation Function（FIF） *** velocity fluctuations of flow along a horizontal plane above the bed were measured using Acoustic Doppler Velocity meter（ADV）and Particle Image Velocimetry（P1V）.The PIV is a powerful technique which enables us to attain high resolution spatial and temporal information of turbulent flow using instantaneous time *** this study,PIV was used for detection of high resolution fractal scaling around a bridge *** results showed that the fractal dimension of flow fluctuated significantly in the longitudinal and transverse directions in the vicinity of the *** was also found that the fractal dimension of velocity fluctuations and shear stresses increased rapidly at vicinity of pier at downstream whereas it remained approximately unchanged far downstream of the *** higher value of fractal dimension was found at a distance equal to one times of the pier diameter in the back of the ***,the average fractal dimension for the streamwise and transverse velocity fluctuations decreased from the centreline to the side wall of the ***,the results from ADV measurement were consistent with the result from PIV,therefore,the ADV enables to detect turbulent characteristics of flow around a circular bridge pier.

关键词： Fractal dimension Fractal interpolation function Fractal scaling Bridge pier Turbulent flow

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Defining laboratory reference values and decision limits＇ populations, intervals, and interpretations

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Asian Journal of Andrology 2010年第1期12卷 83-90页

作者： james C. Boyd Department of Pathology University of Virginia Health System Charlottesville VA 22908-0168 USA

This article provides a brief overview of various approaches that may be utilized for the analysis of human semen test results. Reference intervals are the most widely used tool for the interpretation of clinical laboratory results. Reference interval development has classically relied on concepts elaborated by the International Federation of Clinical Chemistry Expert Panel on Reference Values during the 1980s. These guidelines involve obtaining and classifying samples from a healthy population of at least 120 individuals and then identifying the outermost 5% of observations to use in defining limits for two-sided or one-sided reference intervals. More recently, decision limits based on epidemiological outcome analysis have also been introduced to aid in test interpretation. The reference population must be carefully defined on the basis of the intended clinical use of the underlying test. To determine appropriate reference intervals for use in male fertility assessment, a reference population of men with documented time to pregnancy of 〈 12 months would be most suitable. However, for epidemiological assessment of semen testing results, a reference population made up ofunselected healthy men would be preferred. Although reference and decision limits derived for individual semen analysis test results will undoubtedly be the interpretational tools of choice in the near future, in the long term, multivariate methods for the interpretation of semen analysis alone or in combination with information from the female partner seem to represent better means for assessing the likelihood of achieving a successful pregnancy in a subfertile couple.

关键词： decision limits fertility assessment human semen testing likelihood ratios reference values semen analysis

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The Mysterious Mid-Carnian “Wet Intermezzo” Global Event

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Journal of Earth Science 2015年第2期26卷 181-191页

作者： james G.Ogg Department of Earth Atmospheric and Planetary Sciences Purdue University Key Laboratory of Biogeology and Environmental Geology of Ministry of Education China University of Geosciences

Approximately 230 million years ago in the middle of the Carnian stage of the Upper Triassic, the sedimentary records in different regional basins display dramatic changes. Tropical carbonate platforms abruptly ended, and engorged river systems left widespread sand-rich layers across inland basins and coastal regions. This pulse lasted less than a million years in some basins, but constituted a permanent shift in others. Following this event, the Late Carnian has the earliest record of significant dinosaurs on land and the emergence of the calcareous nannoplankton in the oceans that now govern Earth＇s carbon cycle. This ＂most distinctive climate change within the Tri- assic＂ has been interpreted by some geoscientists as a global disruption of the Earth＇s land-ocean-biological system. The eruption of the Wrangellia large igneous province may have been the trigger for a sudden carbon-dioxide-induced warming and associated increased rainfall in some of these regions. Indeed, some workers have proposed that this ＂wet intermezzo＂ warming event is a useful analog to aid in predicting the effects of our future greenhouse on land ecosystems and ocean chemistry. However, the understanding of the onset, duration, global impacts and relatively rapid termination of this postulated warming pulse has been hindered by lack of a global dataset with inter-calibrated terrestrial and marine biostratigraphy, precise radio-isotopic ages, stable isotope records of temperature and the carbon system, and cycle-calibrated rates of regional and global change.

关键词： Triassic Carnian climate pluvial Wrangellia carbon isotope excursion dolomite China LIP Yangtze Platform Wet Intermezzo large igneous province.

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A comparison of the ballistic behaviour of conventionally sintered and additively manufactured alumina

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Defence Technology（防务技术） 2020年第2期16卷 275-282页

作者： Gareth james Appleby-Thomas Kevin Jaansalu Amer Hameed Jonathan Painter james Shackel Julie Rowley Centre for Defence Engineering Cranfield Defence and SecurityCranfield UniversityShrivenhamSwindonSN68LAUK Department of Chemistry and Chemical Engineering Royal Military College of CanadaPO Box 17000Station ForcesKingstonOntarioK7K 7B4Canada

Production of ceramic armour solutions on-demand/in-theatre would have significant logistical and military ***,even assuming that such technologies could be successfully deployed in the field,such near net-shape manufacturing technology is relatively immature compared to conventional sintering of *** this study,the ballistic performance of a series of additively manufactured(AM)/rapidly-prototyped(RP)alumina tiles of 97.2%of the density of Sintox FATM were investigated using both forward-and reverse-ballistic *** experiments,undertaken with compressed gasguns,employed the depth-of-penetration technique and flash X-ray as primary diagnostics to interrogate both efficiency of penetration and projectile-target interaction,*** RP alumina was found to exhibit useful ballistic properties,successfully defeating steel-cored(AP)7.62×39 mm BXN rounds at velocities of up-to c.a.850 m/s,while exhibiting comparable failure modes to conventionally sintered armour-grade Sintox ***,where a<1%by *** dopant was introduced into the RP material failure modes changed dramatically with performance dropping below that of conventionally sintered ***,the results from both sets of experiments were complimentary and clearly indicated the potential of such RP materials to play an active role in provision of real-world body armour solutions provided quality control of the RP material can be maintained.

关键词： Additive manufacture Rapidly prototyped Body armour Ballistics Ceramics

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