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Modeling chemical releases from building materials: The search for extended validity domain and parsimony

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Building Simulation 2021年第4期14卷 1277-1293页

作者： Lei Huang Alice Micolier Henri P.gavin Olivier Jolliet Department of environmental Health Sciences School of Public HealthUniversity of MichiganAnn ArborMIUSA I2M CNRSUMR 5295351 Cours de la LibérationUniversity of Bordeaux33400TalenceFrance Department of Civil and environmental engineering Duke UniversityDurhanNCUSA

This study aims to systematically evaluate and extend the validity domains of multiple mechanistic models of chemical emissions from building materials. We compare the validity domain of the analytical solution with four numerical solutions for a single layer material with one convective surface and a wide range of chemical properties, material thicknesses, and simulation time. We also develop a parsimonious simplified model, ensuring the widest possible validity domain with minimum simulation time. For diffusion coefficients lower than 10−15 m^(2)/s, accuracy of the analytical solution requires at least 5000 positive roots. The numerical method using uneven discretization and finite difference approximation for the boundary conditions is the best numerical solution. The parsimonious combined D- and K-limited model achieves similar accuracy as the best numerical solution except slight overestimates at the interface between the D- and K-limited zones, while having simpler computations and much shorter simulation time. These models show good agreement against experimental data. This study demonstrates that the complex analytical solution can be well approximated by a simpler model with a wide validity domain, enabling the high-throughput screenings of a large number of chemical-product combinations.

关键词： emission models building materials organic chemicals analytical solution numerical and simplified solutions high-throughput assessment

Gap analysis in decision support systems for real-estate in the era of the digital earth

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International Journal of Digital earth 2021年第1期14卷 121-138页

作者： Hamidreza Rabiei-Dastjerdi gavin McArdle Stephen A.Matthews Peter Keenan School of Computer Science and CeADAR University College Dublin(UCD)DublinIreland Department of Sociology&Criminology and Department of Anthropology The Pennsylvania State UniversityUniversity ParkUSA School of Business University College Dublin(UCD)DublinIreland

Searching for a property is inherently a multicriteria spatial decision.The decision is primarily based on three high-level criteria composed of household needs,building facilities,and location characteristics.Location choice is driven by diverse characteristics;including but not limited to environmental factors,access,services,and the socioeconomic status of a neighbourhood.This article aims to identify the gap between theory and practice in presenting information on location choice by using a gap analysis methodology through the development of a sevenfactor classification tool and an assessment of international property websites.Despite the availability of digital earth data,the results suggest that real-estate websites are poor at providing sufficient location information to support efficient spatial decision making.Based on a case study in Dublin,Ireland,we find that although neighbourhood digital earth data may be readily available to support decision making,the gap persists.We hypothesise that the reason is two-fold.Firstly,there is a technical challenge to transform location data into usable information.Secondly,the market may not wish to provide location information which can be perceived as negative.We conclude this article with a discussion of critical issues necessary for designing a spatial decision support system for real-estate decision making.

关键词： Gap analysis digital earth spatial decision support systems(SDSS) spatial data real-estate Dublin

Bridge Maintenance Robotic Arm:Mechanical Technique to Reduce the Nozzle Force of a Sandblastine Rig

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武汉理工大学学报 2006年第S1期28卷 12-18页

作者： Nathan Kirchner gavin Paul Centre for Autonomous Systems Kevin Kirby Suite Building 2Level 6University of Technology Sydney Broadway 2007 NSW. Australia

This paper describes a mechanical technique to reduce the nozzle reaction force of a sandblasting rig. A theoretical evaluation of the magnitudes and direction of action of typical sandblasting nozzle forces has been conducted and a technique for exploiting available energy in order to reduce the magnitude of the forces at the nozzle has been developed.experimental results from a variety of tests in different configurations have confirmed the theoretically determined force magnitude’s accuracy and shown that forces of up to 106N can be present in typical sandblasting operations. The results have also shown that an up to 77% reduction of force at the nozzle can be achieved by applying the developed mechanicaltechnique.

关键词： sandblasting nozzle force maintenance robot mechanical advantage

A review of bridge scour monitoring techniques

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Journal of Rock Mechanics and Geotechnical engineering 2014年第2期6卷 138-149页

作者： L.J.Prendergast K.gavin School of Civil.Structural and environmental engineering University College Dublin

The high profile failure of the Malahide Viaduct in Dublin, Ireland, which is a part of the eU TeN-T network of critical transport links, was caused by foundation scour. Scour is a common soil-structure interaction problem. In light of current changes in climate, increasing frequency of flooding, coupled with the increasing magnitude of these flood events, will lead to a higher risk of bridge failure. Moni- toring scour is of paramount importance to ensure the continued safe operation of the aging bridge asset network. Most monitoring regimes are based on expensive underwater instrumentation that can often be subjected to damage during times of flooding, when scour risk is at its highest. This paper presents a critical review of existing scour monitoring equipments and methodologies with a particular focus on those using the dynamic response of the structure to indicate the existence and severity of the scour phenomenon affecting the structure. A sensitivity study on a recently developed monitoring method is also undertaken.

关键词： Scour Dynamics Monitoring Instruments Bridge failure

ACe2/Ang-(1-7) signaling and vascular remodeling

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Science China(Life Sciences) 2014年第8期57卷 802-808页

作者： ZHANG ZhenZhou CHeN LaiJiang ZHONG JiuChang GAO PingJin OUDIT gavin Y. State Key Laboratory of Medical Genomics Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine Shanghai Key Laboratory of Hypertension Shanghai Institute of Hypertension Department of Medicine University of Alberta Mazankowski Alberta Heart Institute

The renin-angiotensin system(RAS)regulates vascular tone and plays a critical role in vascular remodeling,which is the result of a complex interplay of alterations in vascular tone and structure.Inhibition of the RAS has led to important pharmacological tools to prevent and treat vascular diseases such as hypertension,diabetic vasculopathy and atherosclerosis.Angiotensin converting enzyme 2(ACe2)was recently identified as a multifunctional monocarboxypeptidase responsible for the conversion of angiotensin(Ang)II to Ang-(1-7).The ACe2/Ang-(1-7)signaling has been shown to prevent cellular proliferation,pathological hypertrophy,oxidative stress and vascular fibrosis.Thus,the ACe2/Ang-(1-7)signaling is deemed to be beneficial to the cardiovascular system as a negative regulator of the RAS.The addition of the ACe2/Ang-(1-7)signaling to the complexities of the RAS may lead to the development of novel therapeutics for the treatment of hypertension and other vascular diseases.The present review considers recent findings regarding the ACe2/Ang-(1-7)signaling and focuses on its regulatory roles in processes related to proliferation,inflammation,vascular fibrosis and remodeling,providing proof of principle for the potential use of ACe2 as a novel therapy for vascular disorders related to vascular remodeling.

关键词：血管紧张素转换酶血管重塑信令心血管疾病心血管系统动脉粥样硬化 RAS 治疗学

A novel approach for removal of an inflatable penile prosthesis reservoir using laparoscopic instruments

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Asian Journal of Andrology 2017年第1期19卷 132-134页

作者： Angie L Staller Courtney M Chang gavin N Wagenheim Run Wang Division of Urology University of Texas McGovern Medical School Houston Texas 77030USA Department of Urology University of Texas MD Anderson Cancer Center HoustonTexas 77030 USA.

In the setting of an infected inflatable penile prosthesis （IPP）, removal of the reservoir is a surgical challenge. We describe a novel technique for IPP reservoir removal at the time of IPP explantation utilizing laparoscopic instruments. We present two cases of infected IPPs requiring complete removal of all components of the implant. The corporal cylinders and scrotal pump were removed via a single penoscrotal incision.

关键词： infected inflatable penile

In vivo study of corneal responses to increased intraocular pressure loading

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eye and Vision 2015年第1期2卷 177-186页

作者： Ahmed elsheikh Charles W.McMonnies Charles Whitford gavin C.Boneham School of engineering University of LiverpoolBrownlow HillLiverpool L693GHUK National Institute for Health Research(NIHR)Biomedical Research Centre Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of OphthalmologyLondonUK School of Optometry and Vision Science University of New South WalesSydneyAustralia

Background:The cornea is responsible for two-thirds of the eye's refractive power which is a function of the shape and refractive index.The aim of this present study is to examine human eyes in vivo for corneal shape changes in response to short-term elevation in intraocular pressure.Methods:Videokeratographic and tonometric assessments at baseline were compared with the same assessments when intraocular pressure was elevated to approximately double(199±22%)the baseline levels using ophthalmodynamometer applanation of the sclera.Composite maps of the cornea and limbus were created by combining topographical assessments for central,nasal,temporal,inferior and superior fixation.Numerical finiteelement simulations were custom built for each subject and the stiffness distribution across corneal surface modified to achieve matches between simulated and experimental data.Results:The stiffness distributions required to achieve simulation-experimental matches showed a consistent trend with the 2.5 mm annulus bounded by the limbus showing a mean stiffness reduction of 47.3±10.8%compared with the central cornea(P=0.001).Conclusions:Corneal structure appears to provide the central cornea with a greater stiffness compared with the peripheral cornea and associated greater tolerance to elevation in intraocular pressure,consistent with the need for stable corneal refraction and vision.The method adopted to examine corneal biomechanical performance in vivo may have applications in additional studies.

关键词： Corneal biomechanics Topography Numerical simulation

Reliability of ultrasound ovarian-adnexal reporting and data system amongst less experienced readers before and after training

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World Journal of Radiology 2022年第9期14卷 319-328页

作者： Prayash Katlariwala Mitchell P Wilson Yeli Pi Baljot S Chahal Roger Croutze Deelan Patel Vimal Patel gavin Low Department of Radiology and Diagnostic Imaging University of AlbertaEdmonton T6G 2B7ABCanada

BACKGROUND The 2018 ovarian-adnexal reporting and data system(O-RADS)guidelines are aimed at providing a system for consistent reports and risk stratification for ovarian lesions found on ultrasound.It provides key characteristics and findings for lesions,a lexicon of descriptors to communicate findings,and risk characterization and associated follow-up recommendation guidelines.However,the ORADS guidelines have not been validated in North American institutions or amongst less experienced readers.AIM To evaluate the diagnostic accuracy and inter-reader reliability of ultrasound ORADS risk stratification amongst less experienced readers in a North American institution with and without pre-test training.MeTHODS A single-center retrospective study was performed using 100 ovarian/adnexal lesions of varying O-RADS scores.Of these cases,50 were allotted to a training cohort and 50 to a testing cohort via a non-randomized group selection process in order to approximately equal distribution of O-RADS categories both within and between groups.Reference standard O-RADS scores were established through consensus of three fellowship-trained body imaging radiologists.Three PGY-4 residents were independently evaluated for diagnostic accuracy and inter-reader reliability with and without pre-test O-RADS training.Sensitivity,specificity,positive predictive value,negative predictive value(NPV),and area under the curve(AUC)were used to measure accuracy.Fleiss kappa and weighted quadratic(pairwise)kappa values were used to measure inter-reader reliability.Statistical significance was PeSULTS Mean patient age was 40±16 years with lesions ranging from 1.2 to 22.5 cm.Readers demonstrated excellent specificities(85%-100%pre-training and 91%-100%post-training)and NPVs(89%-100%pre-training and 91-100%post-training)across the O-RADS categories.Sensitivities were variable(55%-100%pre-training and 64%-100%post-training)with malignant ORADS 4 and 5 Lesions pre-training and post-training AUC values of 0.87-0.95 and 0.94-098,respectively

关键词： Ovarian-adnexal reporting and data system Ovary Malignancy Accuracy Reliability Ultrasound

Denitrification from nitrogen-fixing biologically crusted soils in a cool desert environment,southeast Utah,USA

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ecological Processes 2013年第1期2卷 156-164页

作者： Nichole N Barger Sarah C Castle gavin N Dean Department of ecology and evolutionary Biology University of ColoradoCampus Box 334BoulderCO 80309-0334USA Department of ecosystem and Conservation Sciences College of Forestry and ConservationUniversity of MontanaMissoulaMT59812USA.

Introduction:Nitrogen fixation by microorganisms within biological soil crust(“biocrust”)communities provides an important pathway for N inputs in cool desert environments where soil nutrients are low and symbiotic N-fixing plants may be rare.estimates of N fixation in biocrusts often greatly exceed that of N accretion rates leading to uncertainty regarding N loss pathways.Methods:In this study we examined nitrogen fixation and denitrification rates in biocrust communities that differed in N fixation potential(low N fixation=light cyanobacterial biocrust,high N fixation=dark cyanolichen crust)at four temperature levels(10,20,30,40°C)and four simulated rainfall levels(0.05,0.2,0.6,1 cm rain events)under controlled laboratory conditions.Results:Acetylene reduction rates(AR,an index of N fixation activity)were over six-fold higher in dark crusts relative to light crusts.Dark biocrusts also exhibited eight-fold higher denitrification rates.There was no consistent effect of temperature on denitrification rates,but there was an interactive effect of water addition and crust type.In light crusts,denitrification rates increased with increasing water addition,whereas the highest denitrification rates in dark crusts were observed at the lowest level of water addition.Conclusions:These results suggest that there are no clear and consistent environmental controls on short-term denitrification rates in these biologically crusted soils.Taken together,estimates of denitrification from light and dark biocrusts constituted 3 and 4%of N fixation rates,respectively suggesting that losses as denitrification are not significant relative to N inputs via fixation.This estimate is based on a previously published conversion ratio of ethylene produced to N fixed that is low(0.295),resulting in high estimates of N fixation.If future N fixation studies in biologically crusted soils show that these ratios are closer to the theoretical 3:1 ratio,denitrification may constitute a more significant loss pathway relative to N fixed.

关键词： Biological soil crust Colorado Plateau Cool desert Denitrification Nitrogen fixation Soil nitrogen cycling