检索结果-南通市图书馆

Open Journal of Statistics 2020年第4期10卷 664-677页

作者： Olusegun Olatayo Alabi Kayode Ayinde Omowumi Esther Babalola Hamidu Abimbola Bello edward charles okon Department of Statistics Federal University of Technology Akure Nigeria

Heteroscedasticity and multicollinearity are serious problems when they exist in econometrics data. These problems exist as a result of violating the assumptions of equal variance between the error terms and that of independence between the explanatory variables of the model. With these assumption violations, Ordinary Least Square Estimator (OLS) will not give best linear unbiased, efficient and consistent estimator. In practice, there are several structures of heteroscedasticity and several methods of heteroscedasticity detection. For better estimation result, best heteroscedasticity detection methods must be determined for any structure of heteroscedasticity in the presence of multicollinearity between the explanatory variables of the model. In this paper we examine the effects of multicollinearity on type I error rates of some methods of heteroscedasticity detection in linear regression model in other to determine the best method of heteroscedasticity detection to use when both problems exist in the model. Nine heteroscedasticity detection methods were considered with seven heteroscedasticity structures. Simulation study was done via a Monte Carlo experiment on a multiple linear regression model with 3 explanatory variables. This experiment was conducted 1000 times with linear model parameters of β0 = 4 , β1 = 0.4 , β2= 1.5

Multi-length scale modeling of carburization,martensitic microstructure evolution and fatigue properties of steel gears

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2020年第14期47卷 157-165页

作者： edward charles Henry Crawford O’Brien Hemantha Kumar Yeddu School of Engineering Newcastle UniversityNewcastle upon TyneNE17RUUnited Kingdom

Multi-length scale modeling is performed to(i)predict the carburized case depth of SAE8620 steel gears by solving the Fick’s second law of diffusion,(ii)model the martensitic microstructure evolution in a grain inside the carburized case as well as to study the effect of stress cycling on retained austenite(RA)and martensite using a 3D phase-field model,(iii)simulate the effect of carburization and different RA contents on macroscale fatigue behavior of SAE8620 steel spur gear using the finite element *** diffusion model predicts that the case depth increases with increasing heat treatment time and *** phase-field simulations show that RA can transform to martensite during fatigue loading,where the extent of the transformation will depend on the type of stresses applied,*** in a high stress regime or low stress regime of fatigue *** transformation of martensite to austenite is also observed in low RA sample under high stress *** macroscale simulations show that the carburized case with high RA gives rise to better fatigue life compared to that with low RA.

关键词： Phase-field model Martensitic transformation Microstructure Gear steel Carburization

The association of diet quality and physical activity with cardiovascular disease and mortality in 85,545 older Australians:A longitudinal study

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Sport and Health Science 2024年第6期13卷 841-850页

作者： Ding Ding Joe Van Buskirk Stephanie Partridge Philip Clare edward Giovannucci Adrian Bauman Nicole Freene Robyn Gallagher Binh Nguyen Sydney School of Public Health Faculty of Medicine and Healththe University of SydneyCamperdownNSW 2006Australia charles Perkins Centre the University of SydneyCamperdownNSW 2006Australia Sydney Local Health District CamperdownNSW 2050Australia School of Health Sciences Faculty of Medicine and Healththe University of SydneyCamperdownNSW 2006Australia National Drug and Alcohol Research Centre UNSW SydneySydneyNSW 2052Australia Departments of Nutrition and Epidemiology Harvard T.H.Chan School of Public HealthBostonMA 02115USA Faculty of Health University of CanberraCanberraACT 2617Australia Susan Wakil School of Nursing and Midwifery the University of SydneyCamperdownNSW 2050Australia

Background:A quality diet and an active lifestyle are both important cornerstones of cardiovascular disease(CVD)***,despite their interlinked effects on metabolic health,the 2 behaviors are rarely considered jointly,particularly within the context of CVD *** examined the independent,interactive,and joint associations of diet and physical activity with CVD hospitalization,CVD mortality,and all-cause ***:CVD-free Australian participants aged 4574 years(n=85,545)reported physical activity,diet,sociodemographic,and lifestyle characteristics at baseline(20062009)and follow-up(20122015),and data were linked to hospitalization and death registries(03/31/2019 for CVD hospitalization and all-cause mortality and 12/08/2017 for CVD mortality).Diet quality was categorized as low,medium,and high based on meeting dietary *** activity was operationalized as(a)total moderate-to-vigorous physical activity(MVPA)as per guidelines,and(b)the composition of MVPA as the ratio of vigorous-intensity physical activity(VPA)to total *** used a left-truncated cause-specific Cox proportional hazards model using time-varying ***:During a median of 10.7 years of follow-up,6576 participants were admitted to the hospital for CVD and 6581 died from all causes(876 from CVD during 9.3 years).A high-quality diet was associated with a 17%lower risk of all-cause mortality than a low-quality diet,and the highest MVPA category(compared with the lowest)was associated with a 44%and 48%lower risk of CVD and all-cause mortality,*** interactions between diet and physical activity were *** all outcomes,the lowest risk combinations involved a high-quality diet and the highest MVPA *** for total MVPA,some VPA was associated with further risk reduction of CVD hospitalization and all-cause ***:For CVD prevention and longevity,one should adhere to both a healthy d

关键词： Diet Physical activity Cardiovascular disease Mortality Cohort studies

Synthesis of Gas Transport through Nano Composite Ceramic Membrane for Esterification and Volatile Organic Compound Separations

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Mechanics Engineering and Automation 2014年第11期4卷 905-913页

作者： Edidiong okon Habiba Shehu edward Gobina CPIMT (Center for Process Integration and Membrane Technology) RGU (The Robert Gordon University) Aberdeen AB10 7G JUnited Kingdom

The transport behaviour of carrier gases with inorganic catalytic ceramic membrane used for ethyl lactate production and VOC （volatile organic compound） recovery in the gauge pressure range of 0.10-1.00 bar and temperature range of 333 K was investigated. The gases include Ar （argon）, N2 （nitrogen） and CO2 （carbon dioxide）. The gas kinetic diameter with respect to permenace was found to occur in the order of At 〉 CO2 〉 N2, which was not in agreement with molecular sieving mechanism of transport after the first dip-coating of the support. However, gas flow rate was found to increase with gauge pressure in the order of Ar 〉 CO2 〉 N2, indicating Knudsen mechanism of transport. The porous ceramic support showed a higher flux indicating Knudsen transport. The surface image of the dip-coated porous ceramic membrane was characterised using SEM （scanning electron microscopy） to determine the surface morphology of the porous support at 333 K.

关键词： Inorganic ceramic membrane permeance gas flow rate and kinetic diameter

Advanced Catalytic Membrane Characterisation and Gas Permeation Properties for Enhanced Ethyl Lactate Conversion

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science and Chemical Engineering 2017年第3期5卷 1-16页

作者： Edidiong okon Habiba Shehu Ifeyinwa Orakwe edward Gobina Center for Process Integration and Membrane Technology School of Engineering the Robert Gordon University Aberdeen UK

In this work, membrane evaluation, gas permeation properties and characterisation have been presented. A silica composite membrane was prepared, characterized and used for the permeation tests with four carrier gases to determine the most suitable carrier gas for enhancing the analysis of esterification product with gas chromatograph. The carrier gases used for the permeation tests were carbon dioxide (CO2), argon (Ar), helium (He) and nitrogen (N2). The permeation analysis was carried out between the gauge pressure range of 0.10 - 1.00 bar and temperature of 60℃. The gas flow rate was found to increase with respect to gauge pressure. The order of the gas flow rate with respect to the gauge pressure was Ar > CO2 > He > N2. The surface morphology and elemental composition of the membrane were analysed using scanning electron microscopy coupled with energy dispersive analysis of x-ray (the Zeiss EVO LS10). The SEM results exhibited a defect-free surface while the EDAX results identified different elements on the spectra including titanium (Ti), silicon (Si) and oxygen (O). Liquid nitrogen adsorption method (Quantachrome 2013 model) was used for the surface area and pore size distribution analysis. The Brunauer-Emmette-Teller (BET) surface area results of the 5th and 6th dip-coated membranes were 1.497 and 0.253 m2/g respectively, while the Barrette-Joyner-Halender (BJH) curves gave a pore size of 4.184 and 4.180 nm respectively for the 5th and 6th dip-coated membranes indicating a mesoporous structure. The BET curve exhibited a type IV isotherm. The BJH curve of the 6th dip-coated membrane showed a significant reduction in flow rate after the modification process. The membrane recorded a permeance in the range of to . The permeance relationship with the inverse square root of the gas molecular weight showed a linear proportionality with the flow of carrier gases confirming Knudsen flow mechanism of gas transport.

关键词： Permeation Characterisation Inorganic Membrane Carrier Gas Transport Es-terification and Adsorption Isotherm

Resin Characterization and Tubular Membrane Transport with Single Gases for Ethyl Lactate Separations for Industrial Purposes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science and Chemical Engineering 2015年第9期3卷 8-14页

作者： Edidiong okon Habiba Shehu Ngozi Nwogu Mohammed Kajama Ifeyinwa Orakwe edward Gobina Center for Process Integration and Membrane Technology (CPIMT) School of Engineering The Robert Gordon University Aberdeen UK

The dip-coating method has been used to prepare silica membrane. The gas flow rate relationship with the gauge pressure showed a Knudsen type of mechanism of gas transport. The flux was found to decrease with respect to temperature indicating non-activation mechanism of transport through the membrane. The order of the gas kinetic diameter with respect to the gas flow rate was He > Ar > CO2 > N2 confirming a molecular sieving mechanism of gas transport. The characterisation of the resin catalysts was carried out using scanning electron microscopy (SEM). The SEM morphology of the Amberlyst 16 resin catalysts showed a defect-free surface before esterification process. Amberlyst 15 catalyst exhibited some defect on the surface indicating a lower resistance to lactic acid and decomposition at higher temperature after the esterification process at 60°C. The order of the gas viscosity with respect to the gas flux was N2 > Ar > CO2 > He.

关键词： Esterification Resin Characterisation Transport Mechanism Ethyl Lactate and Permeability

Glucose and Electrolytes Concentrations in Blood and Saliva Samples amongst Diabetics

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Diabetes Mellitus 2019年第2期9卷 39-49页

作者： Mieebi Martin Wankasi Eni-yimini Solomon Agoro charles German Ikimi Edidiong okon Tommy The Department of Medical Laboratory Science College of Health Science Niger Delta University Wilberforce Island Nigeria Enis Biomedicals and Forensics (EBF) LTD. Yenagoa Nigeria Department of Biochemistry Federal University Otuoke Otuoke Nigeria Department of Haematology and Blood Transfusion Federal Medical Centre Yenagoa Nigeria

Diabetes mellitus is a group of metabolic disorders of carbohydrate metabolism in which glucose is underutilized, producing hyperglycaemia. The management requires proper maintenance of glucose and electrolytes within its optimum concentrations. The study was designed to evaluate the possibility of using saliva as an alternative non-invasive sample for the determination of electrolytes. A total of 100 samples were utilized consisting of equal number of control (non-diabetics) and diabetic groups. Fasting blood and saliva were collected employing standard methods. The biochemical parameters were analysed using WHO approved methods and procedures. Independent samples t-test and Pearson correlation were the statistical tools used for the data analysis obtained from SPSS package (version 20). The study revealed a significant increase (p < 0.05) in concentrations of blood and salivary glucose, potassium and calcium when controls were compared to diabetics. Moreover, there was a high level of semblances and patterns between plasma and salivary electrolytes, except for potassium. Therefore, electrolytes and glucose results gotten from the use of saliva could be used to equate to that of blood. Hence, instances of non-accessibility of blood, saliva could be of help.

关键词： Saliva Blood Electrolytes Glucose Non-Invasive

What do we know about housing supply?The case of Hong Kong SAR

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Economic and Political Studies 2020年第1期8卷 6-20页

作者： charles Ka Yui Leung Joe Cho Yiu Ng edward Chi Ho Tang Department of Economics and Finance City University of Hong KongHong Kong SARChina Department of Economics and Finance Hong Kong Shue Yan UniversityHong Kong SARChina

The house price in the Hong Kong SAR of China is well-known to be‘unaffordable’.This paper relates the macroeconomy with the housing market of Hong Kong and argues that the housing supply plays a vital role in explaining the *** paper also shows that there are some practical challenges in understanding the housing supply of Hong Kong,including the potentially complicated ownership structure of real estate *** the discussion centres on the situation of Hong Kong,its lesson may also apply to housing markets in other small open economies.

关键词： New housing supply oligopolistic market structure ownership structure real estate development real estate developers

Hydrogen Separation Using Pt-Alumina Impregnated Membrane

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Energy and Power Engineering 2015年第9期7卷 412-417页

作者： Mohammed N. Kajama Ngozi C. Nwogu Edidiong O. okon Habiba Shehu Ify Orakwe edward Gobina Centre for Process Integration and Membrane Technology (CPIMT) School of Engineering The Robert Gordon University Aberdeen UK

A tubular commercial mesoporous support was used to prepare a Pt impregnated membrane using the reservoir method and tested for moderate temperature (300°C) gas transport of hydrogen (H2), helium (He) and nitrogen (N2) gas molecules. H2 and N2 gas permeation of 6.1 and 4.5 l/min at 1.0 barg feed pressure and 25°C respectively was obtained from the support. On the other hand, H2 and N2 gas permeation of 4.6 and 1.7 l/min at 1.0 barg feed pressure and 25°C respectively was also obtained from the Pt membrane. Selectivity of H2 over He of 1.96 at 300°C and 1.6 barg for the Pt membrane was obtained and found to be higher than that of the theoretical Knudsen selectivity. Also, a selectivity of H2 over N2 of 2.72 at 25°C and 1.0 barg was obtained and found to be close to that of the theoretical Knudsen selectivity. The gas permeation and the selectivity performance of the membrane were evaluated.

关键词： Tubular Support Pt Membrane Hydrogen Selectivity Permeation Temperature

Recurrent ectopic pancreatitis of the jejunum and mesentery over a 30-year period

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Hepatobiliary & Pancreatic Diseases International 2011年第2期10卷 218-220页

作者： John CT Wong Charlotte Robinson edward C Jones Alison Harris charles Zwirewich Robert Wakefield Richard K Simons Eric M Yoshida Department of Medicine Department of Medicine 2775 Laurel StreetUniversity of British Columbia VancouverBritish ColumbiaCanadaV5Z 1M9 Department of Radiology Department of Medicine 2775 Laurel StreetUniversity of British Columbia VancouverBritish ColumbiaCanadaV5Z 1M9 Department of Pathology and Laboratory Medicine Department of Medicine 2775 Laurel StreetUniversity of British Columbia VancouverBritish ColumbiaCanadaV5Z 1M9 Department of Surgery Department of Medicine 2775 Laurel StreetUniversity of British Columbia VancouverBritish ColumbiaCanadaV5Z 1M9 Division of Gastroenterology Department of Medicine 2775 Laurel StreetUniversity of British Columbia VancouverBritish ColumbiaCanadaV5Z 1M9

BACKGROUND:Ectopic pancreas is defined as pancreatic tissue found outside its usual anatomical position,with no ductal or vascular communication with the native pancreas. We describe a case of ectopic pancreas of the small bowel and mesentery causing recurrent episodes of pancreatitis, initially suspected on computed tomography(CT)and magnetic resonance cholangiopancreatography(MRCP),and confirmed on histological review of the resection. METHODS:A 67-year-old woman presented with clinical symptoms and biochemical evidence of *** had similar episodes over the past 30 years with unrevealing investigations,and was concluded to have idiopathic pancreatitis. She underwent CT and MRCP,with findings suggestive of ectopic pancreas,a diagnosis confirmed on histology of the resection. RESULTS:MRCP identified a mass in the proximal small bowel mesentery isointense to the native pancreas,with a small duct draining into a proximal jejunal *** resected specimen consisted of normal parenchyma with lobulated acinar tissue with scattered islets of Langerhans,an occasional ductular structure,and admixed areas of adipose *** patient remained asymptomatic with normal biochemistry six months post-operatively. CONCLUSION:In an individual with abdominal pain,elevated serum amylase/lipase,but imaging findings of a normal native pancreas,ectopic pancreatitis should be considered,and can be evaluated by CT and MRCP.

关键词： ectopic pancreas gastrointestinal tract endoscopic ultrasound computed tomography magnetic resonance cholangiopancreatography