Electroosmotic transport and entropy generation play a decisive role in regulating efficiency,stability,and energy cost of non-Newtonian nanoblood flows in stenosed arteries,particularly with tapered geometries.Thisst...Electroosmotic transport and entropy generation play a decisive role in regulating efficiency,stability,and energy cost of non-Newtonian nanoblood flows in stenosed arteries,particularly with tapered geometries.Thisstudy develops a unified model to analyze ZnO-Williamson nanoblood flow through a stenosed artery with converging,diverging,and non-tapered configurations,incorporating electroosmosis,viscous dissipation,and entropy production.The arterial walls are assumed to be electrically charged with a no-slip condition to induce electroosmotic propulsionalong the endothelial surface.The partial differential equations are nondimensionalized to a coupled system ofnonlinear ordinary differential equations,which are solved numerically using a MATLAB-based shooting technique.Parametric investigation is conducted for Brinkman,Grashof,and Weissenberg numbers,ZnO fractional volume,volumetric flow rate,and Helmholtz-Smoluchowski velocity to quantify their influences on axial velocity,wall shearstress,impedance resistance,temperature distribution,entropy generation,Bejan number,and streamline topology.The axial velocity decreases radially with increasing Brinkman number for all arterial geometries.Increasing ZnOnanoparticles improves thermal transport owing to enhanced effective thermal conductivity but simultaneously elevatesentropy generation due to increased viscous dissipation.Higher Weissenberg numbers suppress entropy production bypromoting elastic stress redistribution and lowering shear-induced irreversibility.Impedance resistance decreases withincreasing stenosis height but increases with stenosis shape parameter and ZnO fractional volume.Streamline analysisshows that buoyancy and viscoelasticity significantly distort flow near the stenosis,while increasing electroosmoticvelocity stabilizes streamlines,suppresses recirculation,and reduces local shear stress and pressure fluctuations.Inconclusion,electroosmotic actuation is most effective in reducing flow resistance in the converging tapered artery,particularly at lower ZnO volume fractions.Overall,the findings highlight the potential of optimized electroosmoticactuation and controlled nanoparticle loading to minimize thermodynamic losses,regulate shear stress,and improveflow uniformity in stenosed vessels,with promising implications for electro-assisted drug delivery,nanotherapeutics,and bio-inspired vascular microfluidic systems.展开更多
Building and construction sector, including infrastructures, are facing many challenges which are scarcity of raw materials, CO2 emissions, lower construction efficiency, and deterioration under corrosive environment ...Building and construction sector, including infrastructures, are facing many challenges which are scarcity of raw materials, CO2 emissions, lower construction efficiency, and deterioration under corrosive environment that cost the world economy $2.5 trillion and this translates to 3.4% of world gross domestic product. This paper presents several examples that show how the use of the nonmetallic materials improved sustainability and life cycles in the built environment by removing the corrosion issue from its root and using durable NM polymers in construction. The paper details recently patented Aramco technology for the use of nonmetallic paving panels that could be used as an alternative to concrete and asphalt paving. Other case studies presented cover use of GFRP Poles for traffic signs and signal poles to replace traditional steel poles. Details of developments for specialist structural application in bridges, in architectural applications, polymers in soils, fibers in pavement manholes and bendable concrete are presented.展开更多
Compacted sand-bentonite mixtures are used as waste containment barriers(e.g.landfill liners and bentonite buffers for nuclear waste)to restrict contaminant transport.The potential for enhanced chemical containment of...Compacted sand-bentonite mixtures are used as waste containment barriers(e.g.landfill liners and bentonite buffers for nuclear waste)to restrict contaminant transport.The potential for enhanced chemical containment of compacted sand-bentonite mixtures due to semipermeable membrane behavior has also been demonstrated.However,the extent to which membrane behavior persists in the presence of highly concentrated chemical solutions,which have been shown to degrade membrane behavior in bentonite-based barriers,remains largely unknown.Moreover,the limiting(threshold)salt concentrations at which membrane behavior of compacted sand-bentonite mixtures is effectively destroyed have not been evaluated.Accordingly,this study quantified the limiting membrane behavior of two duplicated specimens of compacted sand-bentonite mixture comprising 15%sodium bentonite(by dry mass)by determining the limiting salt concentrations at which measurable membrane behavior was eliminated.The specimens were exposed to increasingly higher source concentrations,Cot,of boundary monovalent salt solutions(KCl and NaCl)until measured values of the membrane efficiency coefficient,ω,were effectively zero.Overall,ωdecreased from an average of 0.032 to zero as Cot increased from 160 mmol/L KCl to 3.27 mol/L NaCl,resulting in limiting threshold salt concentrations for the two tests between 1.63 mol/L and 3.27 mol/L NaCl,which are significantly higher than those at which measurable membrane behavior has previously been demonstrated.展开更多
This study integrates seismic and petrophysical data to evaluate the subsurface geology of the Keva Field,located onshore in the Niger Delta,with the objective of constructing a 3D geological model and estimating the ...This study integrates seismic and petrophysical data to evaluate the subsurface geology of the Keva Field,located onshore in the Niger Delta,with the objective of constructing a 3D geological model and estimating the recoverable hydrocarbon volumes.Seismic lines and well log data from six wells—KV-2,KV-3,KV-4,KV-5,KV-6,and KV-7—were utilized for the interpretation.The seismic profiles revealed that the KV-4 well is the only well drilled on the up-thrown side of a significant horst fault block,bounded by four major normal faults,while all the other wells penetrated the downthrown side.Petrophysical analysis identified three key reservoirs,C500,D200,and E900,which exhibit excellent reservoir quality with high net-to-gross ratios,good porosity,and high hydrocarbon saturation.The identified depositional environments are tidal-and fluvial-dominated shoreface settings,with sheet sands deposited in distributary splay systems.The C500,D200,and E900 reservoirs have Gas Initially in Place(GIIP)values of 156.37,28.44,and 27.89 BSCF,respectively,with corresponding Estimated Ultimate Recovery(EUR)values of 104.77,19.06,and 18.69 BSCF,respectively.The Stock Tank Original Oil in Place(STOOIP)values are 24.43,91.29,and 86.41 MMSTB,with EURs of 7.32,27.4,and 25.92 MMSTB,respectively.The combined GIIP is 212.72 BSCF with EUR of 142.52 BSCF,while the total STOOIP is 202.13 MMSTB with a recoverable volume of 60.64 MMSTB.The reservoirs present an average porosity of 22.62%,with gas saturation of 84.66%and oil saturation of 73%.The evaluated reservoir qualities suggest high potential for optimized hydrocarbon production.展开更多
The significant threat of wildfires to forest ecology and biodiversity,particularly in tropical and subtropical regions,underscores the necessity for advanced predictive models amidst shifting climate patterns.There i...The significant threat of wildfires to forest ecology and biodiversity,particularly in tropical and subtropical regions,underscores the necessity for advanced predictive models amidst shifting climate patterns.There is a need to evaluate and enhance wildfire prediction methods,focusing on their application during extended periods of intense heat and drought.This study reviews various wildfire modelling approaches,including traditional physical,semi-empirical,numerical,and emerging machine learning(ML)-based models.We critically assess these models’capabilities in predicting fire susceptibility and post-ignition spread,highlighting their strengths and limitations.Our findings indicate that while traditional models provide foundational insights,they often fall short in dynamically estimating parameters and predicting ignition events.Cellular automata models,despite their potential,face challenges in data integration and computational demands.Conversely,ML models demonstrate superior efficiency and accuracy by leveraging diverse datasets,though they encounter interpretability issues.This review recommends hybrid modelling approaches that integrate multiple methods to harness their combined strengths.By incorporating data assimilation techniques with dynamic forecasting models,the predictive capabilities of ML-based predictions can be significantly enhanced.This review underscores the necessity for continued refinement of these models to ensure their reliability in real-world applications,ultimately contributing to more effective wildfire mitigation and management strategies.Future research should focus on improving hybrid models and exploring new data integration methods to advance predictive capabilities.展开更多
This review describes the conceptual and clinical relations between irritable bowel syndrome (IBS), other functional, somatoform, and mental disorders, and points to appropriate future conceptualizations. IBS is consi...This review describes the conceptual and clinical relations between irritable bowel syndrome (IBS), other functional, somatoform, and mental disorders, and points to appropriate future conceptualizations. IBS is considered to be a functional somatic syndrome (FSS) with a considerable symptom overlap with other FSSs like chronic fatigue syndrome or fibromyalgia syndrome. IBS patients show an increased prevalence of psychiatric symptoms and disorders, especially depression and anxiety. IBS is largely congruent with the concepts of somatoform and somatic symptom disorders. Roughly 50% of IBS patients complain of gastrointestinal symptoms only and have no psychiatric comorbidity. IBS concepts, treatment approaches, as well as health care structures should acknowledge its variability and multidimensionality by: (1) awareness of additional extraintestinal and psychobehavioral symptoms in patients with IBS; (2) general and collaborative care rather than specialist and separated care; and (3) implementation of “interface disorders” to abandon the dualistic classification of purely organic or purely mental disorders.展开更多
BACKGROUND 1,3-beta-D-glucan(BG)is a ubiquitous cell wall component of gut microorganisms.We hypothesized that the serum levels of BG could reflect active intestinal inflammation in patients with inflammatory bowel di...BACKGROUND 1,3-beta-D-glucan(BG)is a ubiquitous cell wall component of gut microorganisms.We hypothesized that the serum levels of BG could reflect active intestinal inflammation in patients with inflammatory bowel disease.AIM To determine whether the serum BG concentrations correlate with intestinal inflammation.METHODS A prospective observational study was performed in a tertiary referral center,from 2016 to 2019,in which serum BG was determined in 115 patients with Crohn’s disease(CD),51 with ulcerative colitis(UC),and 82 controls using a photometric detection kit.Inflammatory activity was determined by ileocolonoscopy,histopathology,magnetic resonance enterography,and biomarkers,including fecal calprotectin(FC),C-reactive protein,and a panel of cytokines.The ability of BG to detect active vs inactive disease was assessed using the area under the receiver operating characteristic curve.In subgroup analysis,serial BG was used to assess the response to therapeutic interventions.RESULTS The serum BG levels were higher in CD patients than in controls(P=0.0001).The BG levels paralleled the endoscopic activity in CD patients and histologic activity and combined endoscopic and histologic activity in both CD and UC patients.The area under the curve(AUC)in receiver operating characteristic analysis to predict endoscopic activity was 0.694[95%confidence interval(CI):0.60-0.79;P=0.001]in CD,and 0.662(95%CI:0.51-0.81;P=0.066)in UC patients.The AUC in receiver operating characteristic analysis to predict histologic activity was 0.860(95%CI:0.77-0.95;P<0.001)in CD,and 0.786(95%CI:0.57-0.99;P=0.015)in UC patients.The cut-off values of BG for both endoscopic and histologic activity were 60μg/mL in CD,and 40μg/mL in UC patients.Performance analysis showed that the results based on BG of 40 and 60μg/mL were more specific for predicting endoscopic activity(71.8%and 87.2%for CD;and 87.5%and 87.5%for UC,respectively)than FC(53.3%and 66.7%for CD;and 20%and 80%for UC,respectively);and also histologic activity(60.5%and 76.3%for CD;and 90.0%and 95.0%for UC,respectively)than FC(41.7%and 50.0%for CD;and 25%and 50%for UC,respectively).Regarding the clinical,endoscopic,and histologic activities,the BG levels were reduced following therapeutic intervention in patients with CD(P<0.0001)and UC(P=0.003).Compared with endoscopic(AUC:0.693;P=0.002)and histologic(AUC:0.868;P<0.001)activity,no significant correlation was found between serum BG and transmural healing based on magnetic resonance enterography(AUC:0.576;P=0.192).Positive correlations were detected between BG and IL-17 in the CD(r:0.737;P=0.001)and the UC group(r:0.574;P=0.005),and between BG and interferon-gamma in the CD group(r:0.597;P=0.015).CONCLUSION Serum BG may represent an important novel noninvasive approach for detecting mucosal inflammation and therapeutically monitoring inflammatory bowel diseases,particularly in CD.展开更多
Estimating weak rock mass modulus has historically proven difficult although this mechanical property is an important input to many types of geotechnical analyses. An empirical database of weak rock mass modulus with ...Estimating weak rock mass modulus has historically proven difficult although this mechanical property is an important input to many types of geotechnical analyses. An empirical database of weak rock mass modulus with associated detailed geotechnical parameters was assembled from plate loading tests per- formed at underground mines in Nevada, the Bakhtiary Dam project, and Portugues Dam project. The database was used to assess the accuracy of published single-variate models and to develop a multivari- ate model for predicting in-situ weak rock mass modulus when limited geoteehnical data are available. Only two of the published models were adequate for predicting modulus of weak rock masses over lim- ited ranges of alteration intensities, and none of the models provided good estimates of modulus over a range of geotechnical properties. In light of this shortcoming, a multivariate model was developed from the weak rock mass modulus dataset, and the new model is exponential in form and has the following independent variables： （1） average block size or joint spacing, （2） field estimated rock strength, （3） dis- continuity roughness, and （4） discontinuity infilling hardness. The multivariate model provided better estimates of modulus for both hard-blocky rock masses and intensely-altered rock masses.展开更多
This paper presents a state of the art machine learning-based approach for automation of a varied class of Internet of things(Io T) analytics problems targeted on 1-dimensional(1-D) sensor data. As feature recommendat...This paper presents a state of the art machine learning-based approach for automation of a varied class of Internet of things(Io T) analytics problems targeted on 1-dimensional(1-D) sensor data. As feature recommendation is a major bottleneck for general Io Tbased applications, this paper shows how this step can be successfully automated based on a Wide Learning architecture without sacrificing the decision-making accuracy, and thereby reducing the development time and the cost of hiring expensive resources for specific problems. Interpretation of meaningful features is another contribution of this research. Several data sets from different real-world applications are considered to realize the proof-of-concept. Results show that the interpretable feature recommendation techniques are quite effective for the problems at hand in terms of performance and drastic reduction in development time.展开更多
This study inventoried the floral diversity of a secondary forest in Tuba,Benguet,Philippines as affected by different intensities of human disturbance.This study is unique from other land use studies in Southeast Asi...This study inventoried the floral diversity of a secondary forest in Tuba,Benguet,Philippines as affected by different intensities of human disturbance.This study is unique from other land use studies in Southeast Asia in having conventional farms as the most disturbed land use while other sites have oil palm plantations.A total of 267 species belonging to 222 genera and 78 families was documented.Results showed that the level of human disturbance is the major factor affecting the floral diversity while the effect of elevation is secondary.The level of human disturbance is significantly associated with species richness,species composition,dominant species and biodiversity indices.Greater human disturbance,as in the case of conventional farms,results in lower species richness,predominantly weed composition,dominant weed species and lower biodiversity indices.On the other hand,lesser human disturbance(as in the case of secondary forest)leads to higher species richness,greater native species composition,dominance of indigenous species,and higher diversity indices.The most disturbed land use experienced the greatest loss of species richness,change in floristic composition and vegetation structure,as well as a shift from native to alien-dominated plant communities.These results showed that the effect of land use change is not limited to species richness but also to species composition,dominant species and biodiversity indices.Locally,the study is an important baseline data for biodiversity conservation of the Marcos Highway Watershed Forest Reserve.展开更多
BACKGROUND Colonoscopy attendance is a key quality parameter in colorectal cancer population screening programmes.Within these programmes,educative interventions with bidirectional contact carried out by trained perso...BACKGROUND Colonoscopy attendance is a key quality parameter in colorectal cancer population screening programmes.Within these programmes,educative interventions with bidirectional contact carried out by trained personnel have been proved to be an important tool for colonoscopy attendance improvement,and because of its huge clinical and economic impact,they have been widely implemented.However,outside of this population programmes,educative measures to improve colonoscopy attendance have been poorly studied and no navigation interventions are usually performed.AIM To investigate the clinical and economic impacts of an educational telephone intervention on colonoscopy attendance outside colorectal cancer screening programmes.METHODS This randomized controlled trial included consecutive patients referred to colonoscopy from primary care centres from November 2017 to May 2018.The intervention group(IG)received a telephone intervention,while the control group(CG)did not.Patients assigned to the IG received an educational telephone call 7 d before the colonoscopy appointment.The intervention was carried out by two nurses with deep endoscopic knowledge who were previously trained for a telephone educational intervention for colonoscopy.The impact on patient compliance with preparedness protocols related to bowel cleansing,antithrombotic management,and sedation scheduling was also evaluated.A second call was conducted to assess patient satisfaction.Intention-to-treat(ITT)and perprotocol(PP)analyses were performed.RESULTS A total of 738 and 746 patients were finally included in the IG and CG respectively.Six hundred thirteen(83%)patients were contacted in the IG.The non-attendance rate was lower in the IG,both in the ITT analysis(IG 8.4%vs CG 14.3%,P<0.001)and in the PP analysis(4.4%vs 14.3%,P<0.001).In a multivariable analysis,belonging to the control group increased the risk of nonattendance in both,the ITT analysis(OR 1.81,95%CI:1.27 to 2.58,P=0.001)and the PP analysis(OR 3.56,95%CI:2.25 to 5.64,P<0.001).There was also a significant difference in compliance with preparedness protocols[bowel cleansing:IG 61.7%vs CG 52.6%(P=0.001),antithrombotic management:IG 92.5%vs CG 62.8%(P=0.001),and sedation scheduling:IG 78.8%vs CG 0%(P≤0.001)].We observed a net benefit of €55600/year after the intervention.The information given before the procedure was rated as excellent by 26%(CG)and 51%(IG)of patients,P≤0.001.CONCLUSION Educational telephone nurse intervention improves attendance,protocol compliance and patient satisfaction in the non-screening colonoscopy setting and has a large economic impact,which supports its imple-mentation and maintenance over time.展开更多
This study aimed to investigate whether saline silt and sandy loam coastal soils could be reclaimed by micro-sprinkler irrigation.The experiments were run using moderately salt-tolerant tall fescue grass.Micro-sprinkl...This study aimed to investigate whether saline silt and sandy loam coastal soils could be reclaimed by micro-sprinkler irrigation.The experiments were run using moderately salt-tolerant tall fescue grass.Micro-sprinkler irrigation in three stages was used to regulate soil matric potential at a 20-cm soil depth.Continued regulation of soil water and salt through micro-sprinkler irrigation consistently resulted in an increasingly large low-salinity region.The application of the three stages of soil wateresalt regulation resulted in an absence of salt accumulation throughout the soil profile and the conversion of highly saline soils into moderately saline soils.There were increases in the plant height,leaf width,leaf length,and tiller numbers of tall fescue throughout the leaching process.The results showed that micro-sprinkler irrigation in three soil water and salt regulation stages can be used to successfully cultivate tall festuca in highly saline coastal soil.This approach achieved better effects in sandy loam soil than in silt soil.Tall fescue showed greater survival rates in sandy loam soil due to the rapid reclamation process,whereas plant growth was higher in silt soil because of effective water conservation.In sandy loam,soil moisture should be maintained during soil reclamation,and in silt soil,soil root-zone environments optimal for the emergence of plants should be quickly established.Micro-sprinkler irrigation can be successfully applied to the cultivation of tall fescue in coastal heavy saline soils under a three-stage soil wateresalt regulation regime.展开更多
[Objective] The research aimed to study influence factors of phosphorus removal by chemical method in sewage treatment system. [ Method] In different reaction systems, removal effect of the phosphorus in sewage by dos...[Objective] The research aimed to study influence factors of phosphorus removal by chemical method in sewage treatment system. [ Method] In different reaction systems, removal effect of the phosphorus in sewage by dosing lime and influence of the constraint factor were stud- ied. [ Result] Lime precipitation method treating high-concentration phosphorus wastewater could not only decline cost of phosphorus removal by chemical method, but also reach better treatment effect under suitable stirring and precipitation conditions by controlling alkalinity and pH. Phosphor- us content of chemical sludge after treatment could reach 9% -12%, with higher recyclable value. E Conclusion] Lime method treating phosphorus- rich sewage was more economic than low-concentration phosphorus sewage, and had very great potential for recycling phosphorus.展开更多
Phosphorus (P) risk indices are commonly used in the USA to estimate the field-scale risk of agricultural P runoff. Because the Ohio P Risk Index is increasingly being used to judge farmer performance, it is important...Phosphorus (P) risk indices are commonly used in the USA to estimate the field-scale risk of agricultural P runoff. Because the Ohio P Risk Index is increasingly being used to judge farmer performance, it is important to evaluate weighting/scoring of all P Index parameters to ensure Ohio farmers are credited for practices that reduce P runoff risk and not unduly penalized for things not demonstrably related to runoff risk. A sensitivity analysis provides information as to how sensitive the P Index score is to changes in inputs. The objectives were to determine 1) which inputs are most highly associated with P Index scores and 2) the relative impact of each input variable on resultant P Index scores. The current approach uses simulations across 6134 Ohio point locations and five crop management scenarios (CMSs), representing increasing soil disturbance. The CMSs range from all no-till, which is being promoted in Ohio, rotational tillage, which is a common practice in Ohio to full tillage to represent an extreme practice. Results showed that P Index scores were best explained by soil test P (31.9%) followed by connectivity to water (29.7%), soil erosion (13.4%), fertilizer application amount (11.3%), runoff class (9.5%), fertilizer application method (2.2%), and finally filter strip (2.0%). Ohio P Index simulations across CMSs one through five showed that >40% scored <15 points (low) while <1.5% scored >45 points (very high). Given Ohio water quality problems, the Ohio P Index needs to be stricter. The current approach is useful for Ohio P Index evaluations and revision decisions by spatially illustrating the impact of potential changes regionally and state-wide.展开更多
BACKGROUND Deep learning,a form of artificial intelligence,has shown promising results for interpreting radiographs.In order to develop this niche machine learning(ML)program of interpreting orthopedic radiographs wit...BACKGROUND Deep learning,a form of artificial intelligence,has shown promising results for interpreting radiographs.In order to develop this niche machine learning(ML)program of interpreting orthopedic radiographs with accuracy,a project named deep learning algorithm for orthopedic radiographs was conceived.In the first phase,the diagnosis of knee osteoarthritis(KOA)as per the standard Kellgren-Lawrence(KL)scale in medical images was conducted using the deep learning algorithm for orthopedic radiographs.AIM To compare efficacy and accuracy of eight different transfer learning deep learning models for detecting the grade of KOA from a radiograph and identify the most appropriate ML-based model for the detecting grade of KOA.METHODS The study was performed on 2068 radiograph exams conducted at the Department of Orthopedic Surgery,Sir HN Reliance Hospital and Research Centre(Mumbai,India)during 2019-2021.Three orthopedic surgeons reviewed these independently,graded them for the severity of KOA as per the KL scale and settled disagreement through a consensus session.Eight models,namely ResNet50,VGG-16,InceptionV3,MobilnetV2,EfficientnetB7,DenseNet201,Xception and NasNetMobile,were used to evaluate the efficacy of ML in accurately classifying radiographs for KOA as per the KL scale.Out of the 2068 images,70%were used initially to train the model,10%were used subsequently to test the model,and 20%were used finally to determine the accuracy of and validate each model.The idea behind transfer learning for KOA grade image classification is that if the existing models are already trained on a large and general dataset,these models will effectively serve as generic models to fulfill the study’s objectives.Finally,in order to benchmark the efficacy,the results of the models were also compared to a first-year orthopedic trainee who independently classified these models according to the KL scale.RESULTS Our network yielded an overall high accuracy for detecting KOA,ranging from 54%to 93%.The most successful of these was the DenseNet model,with accuracy up to 93%;interestingly,it even outperformed the human first-year trainee who had an accuracy of 74%.CONCLUSION The study paves the way for extrapolating the learning using ML to develop an automated KOA classification tool and enable healthcare professionals with better decision-making.展开更多
In this work, an experimental study combined with numerical simulation was conducted to investigate the potential of chemically enhanced water alternating gas （CWAG） injection as a new enhanced oil recovery method. ...In this work, an experimental study combined with numerical simulation was conducted to investigate the potential of chemically enhanced water alternating gas （CWAG） injection as a new enhanced oil recovery method. The unique feature of this new method is that it uses alkaline, surfactant, and polymer additives as a chemical slug which is injected during the water alternating gas （WAG） process to reduce the interfacial tension （IFT） and simultaneously improve the mobility ratio. In essence, the proposed CWAG process involves a combination of chemical flooding and immiscible carbon dioxide （CO2） injection and helps in IFT reduction, water blocking reduction, mobility control, oil swelling, and oil viscosity reduction due to CO2 dissolution. Its performance was compared with the conventional immiscible water alter- nating gas （I-WAG） flooding. Oil recovery utilizing CWAG was better by 26 % of the remaining oil in place after waterflooding compared to the recovery using WAG conducted under similar conditions. The coreflood data （cumulative oil and water production） were history mat- ched via a commercial simulator by adjusting the relative permeability curves and assigning the values of the rock and fluid properties such as porosity, permeability, and the experimentally determined IFT data. History matching ofthe coreflood model helped us optimize the experiments and was useful in determining the importance of the parameters influencing sweep efficiency in the CWAG process. The effectiveness of the CWAG process in pro- viding enhancement of displacement efficiency is evident in the oil recovery and pressure response observed in the coreflood. The results of sensitivity analysis on CWAG slug patterns show that the alkaline-surfactant-polymer injection is more beneficial after CO2 slug injection due to oil swelling and viscosity reduction. The CO2 slug size analysis shows that there is an optimum CO2 slug size, around 25 % pore volume which leads to a maximum oil recovery in the CWAG process. This study shows that the ultralow IFT system, i.e., IFT equaling 10 2 or 10 3 mN/ m, is a very important parameter in CWAG process since the water blocking effect can be minimized.展开更多
This paper presents a novel architecture of combining the linear array of antenna elements, where each antenna element has digitally selectable true time-delays as weights. Use of time-delays for beam-formation inhere...This paper presents a novel architecture of combining the linear array of antenna elements, where each antenna element has digitally selectable true time-delays as weights. Use of time-delays for beam-formation inherently makes the phased array network a wideband system. In particular, this technique envisage a new method of sharing antenna elements, by fixed overlapped sub-array architecture, which is able to maintain permissible element spacing to avoid grating lobe in antenna pattern. Moreover, this scheme additionally offers an easier null steering capability to the subarray architecture. This method essentially eliminates the need for intensive computation of complex weight vectors attached to each antenna element.展开更多
The Internet has become a means for socialising, shopping, and keeping informed. The true potential of the net is yet to be explored, given the many new electronic devices that can now access it. Online shopping is gr...The Internet has become a means for socialising, shopping, and keeping informed. The true potential of the net is yet to be explored, given the many new electronic devices that can now access it. Online shopping is growing exponentially. Nevertheless, some products are easy to sell online, while others are still better to be sold at the local store. This paper aims to present a model that identifies the attributes that can improve the marketability of product by lnternet： brand, ＂touch and feel＂, scarcity, price, and cost of returns. The model is being tested in 14 bricks and clicks retailers. Interviews with top management evaluate the validity of the attributes considered. All interviewed persons consider all of these attributes like a valid tool to select which products they can sell by Internet. The positive effects are the reduction of unsold goods, the increasing of visited pages in the web site, the reduction of costs due to returns, the increasing of income, and the rationalization of the offer. The information could help retailers adapt their strategies to fit customer＇s needs and attract and retain customers. From the marketing point of view, the knowledge from this study could help to create marketing strategies tailored to respond to online consumer＇s specific requirements and needs.展开更多
基金funded by the Ministry of Higher Education,Malaysia,under the Fundamental Research Grant Scheme FRGS/1/2023/STG06/UM/02/4(Project FP069-2023)。
文摘Electroosmotic transport and entropy generation play a decisive role in regulating efficiency,stability,and energy cost of non-Newtonian nanoblood flows in stenosed arteries,particularly with tapered geometries.Thisstudy develops a unified model to analyze ZnO-Williamson nanoblood flow through a stenosed artery with converging,diverging,and non-tapered configurations,incorporating electroosmosis,viscous dissipation,and entropy production.The arterial walls are assumed to be electrically charged with a no-slip condition to induce electroosmotic propulsionalong the endothelial surface.The partial differential equations are nondimensionalized to a coupled system ofnonlinear ordinary differential equations,which are solved numerically using a MATLAB-based shooting technique.Parametric investigation is conducted for Brinkman,Grashof,and Weissenberg numbers,ZnO fractional volume,volumetric flow rate,and Helmholtz-Smoluchowski velocity to quantify their influences on axial velocity,wall shearstress,impedance resistance,temperature distribution,entropy generation,Bejan number,and streamline topology.The axial velocity decreases radially with increasing Brinkman number for all arterial geometries.Increasing ZnOnanoparticles improves thermal transport owing to enhanced effective thermal conductivity but simultaneously elevatesentropy generation due to increased viscous dissipation.Higher Weissenberg numbers suppress entropy production bypromoting elastic stress redistribution and lowering shear-induced irreversibility.Impedance resistance decreases withincreasing stenosis height but increases with stenosis shape parameter and ZnO fractional volume.Streamline analysisshows that buoyancy and viscoelasticity significantly distort flow near the stenosis,while increasing electroosmoticvelocity stabilizes streamlines,suppresses recirculation,and reduces local shear stress and pressure fluctuations.Inconclusion,electroosmotic actuation is most effective in reducing flow resistance in the converging tapered artery,particularly at lower ZnO volume fractions.Overall,the findings highlight the potential of optimized electroosmoticactuation and controlled nanoparticle loading to minimize thermodynamic losses,regulate shear stress,and improveflow uniformity in stenosed vessels,with promising implications for electro-assisted drug delivery,nanotherapeutics,and bio-inspired vascular microfluidic systems.
文摘Building and construction sector, including infrastructures, are facing many challenges which are scarcity of raw materials, CO2 emissions, lower construction efficiency, and deterioration under corrosive environment that cost the world economy $2.5 trillion and this translates to 3.4% of world gross domestic product. This paper presents several examples that show how the use of the nonmetallic materials improved sustainability and life cycles in the built environment by removing the corrosion issue from its root and using durable NM polymers in construction. The paper details recently patented Aramco technology for the use of nonmetallic paving panels that could be used as an alternative to concrete and asphalt paving. Other case studies presented cover use of GFRP Poles for traffic signs and signal poles to replace traditional steel poles. Details of developments for specialist structural application in bridges, in architectural applications, polymers in soils, fibers in pavement manholes and bendable concrete are presented.
文摘Compacted sand-bentonite mixtures are used as waste containment barriers(e.g.landfill liners and bentonite buffers for nuclear waste)to restrict contaminant transport.The potential for enhanced chemical containment of compacted sand-bentonite mixtures due to semipermeable membrane behavior has also been demonstrated.However,the extent to which membrane behavior persists in the presence of highly concentrated chemical solutions,which have been shown to degrade membrane behavior in bentonite-based barriers,remains largely unknown.Moreover,the limiting(threshold)salt concentrations at which membrane behavior of compacted sand-bentonite mixtures is effectively destroyed have not been evaluated.Accordingly,this study quantified the limiting membrane behavior of two duplicated specimens of compacted sand-bentonite mixture comprising 15%sodium bentonite(by dry mass)by determining the limiting salt concentrations at which measurable membrane behavior was eliminated.The specimens were exposed to increasingly higher source concentrations,Cot,of boundary monovalent salt solutions(KCl and NaCl)until measured values of the membrane efficiency coefficient,ω,were effectively zero.Overall,ωdecreased from an average of 0.032 to zero as Cot increased from 160 mmol/L KCl to 3.27 mol/L NaCl,resulting in limiting threshold salt concentrations for the two tests between 1.63 mol/L and 3.27 mol/L NaCl,which are significantly higher than those at which measurable membrane behavior has previously been demonstrated.
基金the support of African Union Commission through the Pan African University Life and Earth Sciences Institute(including Health and Agriculture),Ibadan,Nigeria,for funding this study。
文摘This study integrates seismic and petrophysical data to evaluate the subsurface geology of the Keva Field,located onshore in the Niger Delta,with the objective of constructing a 3D geological model and estimating the recoverable hydrocarbon volumes.Seismic lines and well log data from six wells—KV-2,KV-3,KV-4,KV-5,KV-6,and KV-7—were utilized for the interpretation.The seismic profiles revealed that the KV-4 well is the only well drilled on the up-thrown side of a significant horst fault block,bounded by four major normal faults,while all the other wells penetrated the downthrown side.Petrophysical analysis identified three key reservoirs,C500,D200,and E900,which exhibit excellent reservoir quality with high net-to-gross ratios,good porosity,and high hydrocarbon saturation.The identified depositional environments are tidal-and fluvial-dominated shoreface settings,with sheet sands deposited in distributary splay systems.The C500,D200,and E900 reservoirs have Gas Initially in Place(GIIP)values of 156.37,28.44,and 27.89 BSCF,respectively,with corresponding Estimated Ultimate Recovery(EUR)values of 104.77,19.06,and 18.69 BSCF,respectively.The Stock Tank Original Oil in Place(STOOIP)values are 24.43,91.29,and 86.41 MMSTB,with EURs of 7.32,27.4,and 25.92 MMSTB,respectively.The combined GIIP is 212.72 BSCF with EUR of 142.52 BSCF,while the total STOOIP is 202.13 MMSTB with a recoverable volume of 60.64 MMSTB.The reservoirs present an average porosity of 22.62%,with gas saturation of 84.66%and oil saturation of 73%.The evaluated reservoir qualities suggest high potential for optimized hydrocarbon production.
基金funding enabled and organized by CAUL and its Member Institutions.
文摘The significant threat of wildfires to forest ecology and biodiversity,particularly in tropical and subtropical regions,underscores the necessity for advanced predictive models amidst shifting climate patterns.There is a need to evaluate and enhance wildfire prediction methods,focusing on their application during extended periods of intense heat and drought.This study reviews various wildfire modelling approaches,including traditional physical,semi-empirical,numerical,and emerging machine learning(ML)-based models.We critically assess these models’capabilities in predicting fire susceptibility and post-ignition spread,highlighting their strengths and limitations.Our findings indicate that while traditional models provide foundational insights,they often fall short in dynamically estimating parameters and predicting ignition events.Cellular automata models,despite their potential,face challenges in data integration and computational demands.Conversely,ML models demonstrate superior efficiency and accuracy by leveraging diverse datasets,though they encounter interpretability issues.This review recommends hybrid modelling approaches that integrate multiple methods to harness their combined strengths.By incorporating data assimilation techniques with dynamic forecasting models,the predictive capabilities of ML-based predictions can be significantly enhanced.This review underscores the necessity for continued refinement of these models to ensure their reliability in real-world applications,ultimately contributing to more effective wildfire mitigation and management strategies.Future research should focus on improving hybrid models and exploring new data integration methods to advance predictive capabilities.
文摘This review describes the conceptual and clinical relations between irritable bowel syndrome (IBS), other functional, somatoform, and mental disorders, and points to appropriate future conceptualizations. IBS is considered to be a functional somatic syndrome (FSS) with a considerable symptom overlap with other FSSs like chronic fatigue syndrome or fibromyalgia syndrome. IBS patients show an increased prevalence of psychiatric symptoms and disorders, especially depression and anxiety. IBS is largely congruent with the concepts of somatoform and somatic symptom disorders. Roughly 50% of IBS patients complain of gastrointestinal symptoms only and have no psychiatric comorbidity. IBS concepts, treatment approaches, as well as health care structures should acknowledge its variability and multidimensionality by: (1) awareness of additional extraintestinal and psychobehavioral symptoms in patients with IBS; (2) general and collaborative care rather than specialist and separated care; and (3) implementation of “interface disorders” to abandon the dualistic classification of purely organic or purely mental disorders.
文摘BACKGROUND 1,3-beta-D-glucan(BG)is a ubiquitous cell wall component of gut microorganisms.We hypothesized that the serum levels of BG could reflect active intestinal inflammation in patients with inflammatory bowel disease.AIM To determine whether the serum BG concentrations correlate with intestinal inflammation.METHODS A prospective observational study was performed in a tertiary referral center,from 2016 to 2019,in which serum BG was determined in 115 patients with Crohn’s disease(CD),51 with ulcerative colitis(UC),and 82 controls using a photometric detection kit.Inflammatory activity was determined by ileocolonoscopy,histopathology,magnetic resonance enterography,and biomarkers,including fecal calprotectin(FC),C-reactive protein,and a panel of cytokines.The ability of BG to detect active vs inactive disease was assessed using the area under the receiver operating characteristic curve.In subgroup analysis,serial BG was used to assess the response to therapeutic interventions.RESULTS The serum BG levels were higher in CD patients than in controls(P=0.0001).The BG levels paralleled the endoscopic activity in CD patients and histologic activity and combined endoscopic and histologic activity in both CD and UC patients.The area under the curve(AUC)in receiver operating characteristic analysis to predict endoscopic activity was 0.694[95%confidence interval(CI):0.60-0.79;P=0.001]in CD,and 0.662(95%CI:0.51-0.81;P=0.066)in UC patients.The AUC in receiver operating characteristic analysis to predict histologic activity was 0.860(95%CI:0.77-0.95;P<0.001)in CD,and 0.786(95%CI:0.57-0.99;P=0.015)in UC patients.The cut-off values of BG for both endoscopic and histologic activity were 60μg/mL in CD,and 40μg/mL in UC patients.Performance analysis showed that the results based on BG of 40 and 60μg/mL were more specific for predicting endoscopic activity(71.8%and 87.2%for CD;and 87.5%and 87.5%for UC,respectively)than FC(53.3%and 66.7%for CD;and 20%and 80%for UC,respectively);and also histologic activity(60.5%and 76.3%for CD;and 90.0%and 95.0%for UC,respectively)than FC(41.7%and 50.0%for CD;and 25%and 50%for UC,respectively).Regarding the clinical,endoscopic,and histologic activities,the BG levels were reduced following therapeutic intervention in patients with CD(P<0.0001)and UC(P=0.003).Compared with endoscopic(AUC:0.693;P=0.002)and histologic(AUC:0.868;P<0.001)activity,no significant correlation was found between serum BG and transmural healing based on magnetic resonance enterography(AUC:0.576;P=0.192).Positive correlations were detected between BG and IL-17 in the CD(r:0.737;P=0.001)and the UC group(r:0.574;P=0.005),and between BG and interferon-gamma in the CD group(r:0.597;P=0.015).CONCLUSION Serum BG may represent an important novel noninvasive approach for detecting mucosal inflammation and therapeutically monitoring inflammatory bowel diseases,particularly in CD.
基金funded by the National Institute of Occupational Safety and Health through research contract 200-2011-39965(Principal Investigator Dr.Kallu)University of Nevada,Reno,NV
文摘Estimating weak rock mass modulus has historically proven difficult although this mechanical property is an important input to many types of geotechnical analyses. An empirical database of weak rock mass modulus with associated detailed geotechnical parameters was assembled from plate loading tests per- formed at underground mines in Nevada, the Bakhtiary Dam project, and Portugues Dam project. The database was used to assess the accuracy of published single-variate models and to develop a multivari- ate model for predicting in-situ weak rock mass modulus when limited geoteehnical data are available. Only two of the published models were adequate for predicting modulus of weak rock masses over lim- ited ranges of alteration intensities, and none of the models provided good estimates of modulus over a range of geotechnical properties. In light of this shortcoming, a multivariate model was developed from the weak rock mass modulus dataset, and the new model is exponential in form and has the following independent variables： （1） average block size or joint spacing, （2） field estimated rock strength, （3） dis- continuity roughness, and （4） discontinuity infilling hardness. The multivariate model provided better estimates of modulus for both hard-blocky rock masses and intensely-altered rock masses.
文摘This paper presents a state of the art machine learning-based approach for automation of a varied class of Internet of things(Io T) analytics problems targeted on 1-dimensional(1-D) sensor data. As feature recommendation is a major bottleneck for general Io Tbased applications, this paper shows how this step can be successfully automated based on a Wide Learning architecture without sacrificing the decision-making accuracy, and thereby reducing the development time and the cost of hiring expensive resources for specific problems. Interpretation of meaningful features is another contribution of this research. Several data sets from different real-world applications are considered to realize the proof-of-concept. Results show that the interpretable feature recommendation techniques are quite effective for the problems at hand in terms of performance and drastic reduction in development time.
基金the funding support from Hedcor,Inc.,a subsidiary of Aboitiz Power that operates run-of-river scheme of electricity generation in the Philippines,as part of their environment protection programco-funded by SEARCA(Southeast Asian Regional Center for Graduate Study and Research in Agriculture)through the Seed Fund for Research and Training。
文摘This study inventoried the floral diversity of a secondary forest in Tuba,Benguet,Philippines as affected by different intensities of human disturbance.This study is unique from other land use studies in Southeast Asia in having conventional farms as the most disturbed land use while other sites have oil palm plantations.A total of 267 species belonging to 222 genera and 78 families was documented.Results showed that the level of human disturbance is the major factor affecting the floral diversity while the effect of elevation is secondary.The level of human disturbance is significantly associated with species richness,species composition,dominant species and biodiversity indices.Greater human disturbance,as in the case of conventional farms,results in lower species richness,predominantly weed composition,dominant weed species and lower biodiversity indices.On the other hand,lesser human disturbance(as in the case of secondary forest)leads to higher species richness,greater native species composition,dominance of indigenous species,and higher diversity indices.The most disturbed land use experienced the greatest loss of species richness,change in floristic composition and vegetation structure,as well as a shift from native to alien-dominated plant communities.These results showed that the effect of land use change is not limited to species richness but also to species composition,dominant species and biodiversity indices.Locally,the study is an important baseline data for biodiversity conservation of the Marcos Highway Watershed Forest Reserve.
基金Supported by Hospital del Mar,Parc de Salut Mar.
文摘BACKGROUND Colonoscopy attendance is a key quality parameter in colorectal cancer population screening programmes.Within these programmes,educative interventions with bidirectional contact carried out by trained personnel have been proved to be an important tool for colonoscopy attendance improvement,and because of its huge clinical and economic impact,they have been widely implemented.However,outside of this population programmes,educative measures to improve colonoscopy attendance have been poorly studied and no navigation interventions are usually performed.AIM To investigate the clinical and economic impacts of an educational telephone intervention on colonoscopy attendance outside colorectal cancer screening programmes.METHODS This randomized controlled trial included consecutive patients referred to colonoscopy from primary care centres from November 2017 to May 2018.The intervention group(IG)received a telephone intervention,while the control group(CG)did not.Patients assigned to the IG received an educational telephone call 7 d before the colonoscopy appointment.The intervention was carried out by two nurses with deep endoscopic knowledge who were previously trained for a telephone educational intervention for colonoscopy.The impact on patient compliance with preparedness protocols related to bowel cleansing,antithrombotic management,and sedation scheduling was also evaluated.A second call was conducted to assess patient satisfaction.Intention-to-treat(ITT)and perprotocol(PP)analyses were performed.RESULTS A total of 738 and 746 patients were finally included in the IG and CG respectively.Six hundred thirteen(83%)patients were contacted in the IG.The non-attendance rate was lower in the IG,both in the ITT analysis(IG 8.4%vs CG 14.3%,P<0.001)and in the PP analysis(4.4%vs 14.3%,P<0.001).In a multivariable analysis,belonging to the control group increased the risk of nonattendance in both,the ITT analysis(OR 1.81,95%CI:1.27 to 2.58,P=0.001)and the PP analysis(OR 3.56,95%CI:2.25 to 5.64,P<0.001).There was also a significant difference in compliance with preparedness protocols[bowel cleansing:IG 61.7%vs CG 52.6%(P=0.001),antithrombotic management:IG 92.5%vs CG 62.8%(P=0.001),and sedation scheduling:IG 78.8%vs CG 0%(P≤0.001)].We observed a net benefit of €55600/year after the intervention.The information given before the procedure was rated as excellent by 26%(CG)and 51%(IG)of patients,P≤0.001.CONCLUSION Educational telephone nurse intervention improves attendance,protocol compliance and patient satisfaction in the non-screening colonoscopy setting and has a large economic impact,which supports its imple-mentation and maintenance over time.
基金supported by the China Scholarship Council(Grant No.201906715015)the Priority Academic Development Program of Jiangsu Higher Education Institutions.
文摘This study aimed to investigate whether saline silt and sandy loam coastal soils could be reclaimed by micro-sprinkler irrigation.The experiments were run using moderately salt-tolerant tall fescue grass.Micro-sprinkler irrigation in three stages was used to regulate soil matric potential at a 20-cm soil depth.Continued regulation of soil water and salt through micro-sprinkler irrigation consistently resulted in an increasingly large low-salinity region.The application of the three stages of soil wateresalt regulation resulted in an absence of salt accumulation throughout the soil profile and the conversion of highly saline soils into moderately saline soils.There were increases in the plant height,leaf width,leaf length,and tiller numbers of tall fescue throughout the leaching process.The results showed that micro-sprinkler irrigation in three soil water and salt regulation stages can be used to successfully cultivate tall festuca in highly saline coastal soil.This approach achieved better effects in sandy loam soil than in silt soil.Tall fescue showed greater survival rates in sandy loam soil due to the rapid reclamation process,whereas plant growth was higher in silt soil because of effective water conservation.In sandy loam,soil moisture should be maintained during soil reclamation,and in silt soil,soil root-zone environments optimal for the emergence of plants should be quickly established.Micro-sprinkler irrigation can be successfully applied to the cultivation of tall fescue in coastal heavy saline soils under a three-stage soil wateresalt regulation regime.
文摘[Objective] The research aimed to study influence factors of phosphorus removal by chemical method in sewage treatment system. [ Method] In different reaction systems, removal effect of the phosphorus in sewage by dosing lime and influence of the constraint factor were stud- ied. [ Result] Lime precipitation method treating high-concentration phosphorus wastewater could not only decline cost of phosphorus removal by chemical method, but also reach better treatment effect under suitable stirring and precipitation conditions by controlling alkalinity and pH. Phosphor- us content of chemical sludge after treatment could reach 9% -12%, with higher recyclable value. E Conclusion] Lime method treating phosphorus- rich sewage was more economic than low-concentration phosphorus sewage, and had very great potential for recycling phosphorus.
文摘Phosphorus (P) risk indices are commonly used in the USA to estimate the field-scale risk of agricultural P runoff. Because the Ohio P Risk Index is increasingly being used to judge farmer performance, it is important to evaluate weighting/scoring of all P Index parameters to ensure Ohio farmers are credited for practices that reduce P runoff risk and not unduly penalized for things not demonstrably related to runoff risk. A sensitivity analysis provides information as to how sensitive the P Index score is to changes in inputs. The objectives were to determine 1) which inputs are most highly associated with P Index scores and 2) the relative impact of each input variable on resultant P Index scores. The current approach uses simulations across 6134 Ohio point locations and five crop management scenarios (CMSs), representing increasing soil disturbance. The CMSs range from all no-till, which is being promoted in Ohio, rotational tillage, which is a common practice in Ohio to full tillage to represent an extreme practice. Results showed that P Index scores were best explained by soil test P (31.9%) followed by connectivity to water (29.7%), soil erosion (13.4%), fertilizer application amount (11.3%), runoff class (9.5%), fertilizer application method (2.2%), and finally filter strip (2.0%). Ohio P Index simulations across CMSs one through five showed that >40% scored <15 points (low) while <1.5% scored >45 points (very high). Given Ohio water quality problems, the Ohio P Index needs to be stricter. The current approach is useful for Ohio P Index evaluations and revision decisions by spatially illustrating the impact of potential changes regionally and state-wide.
文摘BACKGROUND Deep learning,a form of artificial intelligence,has shown promising results for interpreting radiographs.In order to develop this niche machine learning(ML)program of interpreting orthopedic radiographs with accuracy,a project named deep learning algorithm for orthopedic radiographs was conceived.In the first phase,the diagnosis of knee osteoarthritis(KOA)as per the standard Kellgren-Lawrence(KL)scale in medical images was conducted using the deep learning algorithm for orthopedic radiographs.AIM To compare efficacy and accuracy of eight different transfer learning deep learning models for detecting the grade of KOA from a radiograph and identify the most appropriate ML-based model for the detecting grade of KOA.METHODS The study was performed on 2068 radiograph exams conducted at the Department of Orthopedic Surgery,Sir HN Reliance Hospital and Research Centre(Mumbai,India)during 2019-2021.Three orthopedic surgeons reviewed these independently,graded them for the severity of KOA as per the KL scale and settled disagreement through a consensus session.Eight models,namely ResNet50,VGG-16,InceptionV3,MobilnetV2,EfficientnetB7,DenseNet201,Xception and NasNetMobile,were used to evaluate the efficacy of ML in accurately classifying radiographs for KOA as per the KL scale.Out of the 2068 images,70%were used initially to train the model,10%were used subsequently to test the model,and 20%were used finally to determine the accuracy of and validate each model.The idea behind transfer learning for KOA grade image classification is that if the existing models are already trained on a large and general dataset,these models will effectively serve as generic models to fulfill the study’s objectives.Finally,in order to benchmark the efficacy,the results of the models were also compared to a first-year orthopedic trainee who independently classified these models according to the KL scale.RESULTS Our network yielded an overall high accuracy for detecting KOA,ranging from 54%to 93%.The most successful of these was the DenseNet model,with accuracy up to 93%;interestingly,it even outperformed the human first-year trainee who had an accuracy of 74%.CONCLUSION The study paves the way for extrapolating the learning using ML to develop an automated KOA classification tool and enable healthcare professionals with better decision-making.
基金the EOR Center at University Technology Petronas for providing financial support
文摘In this work, an experimental study combined with numerical simulation was conducted to investigate the potential of chemically enhanced water alternating gas （CWAG） injection as a new enhanced oil recovery method. The unique feature of this new method is that it uses alkaline, surfactant, and polymer additives as a chemical slug which is injected during the water alternating gas （WAG） process to reduce the interfacial tension （IFT） and simultaneously improve the mobility ratio. In essence, the proposed CWAG process involves a combination of chemical flooding and immiscible carbon dioxide （CO2） injection and helps in IFT reduction, water blocking reduction, mobility control, oil swelling, and oil viscosity reduction due to CO2 dissolution. Its performance was compared with the conventional immiscible water alter- nating gas （I-WAG） flooding. Oil recovery utilizing CWAG was better by 26 % of the remaining oil in place after waterflooding compared to the recovery using WAG conducted under similar conditions. The coreflood data （cumulative oil and water production） were history mat- ched via a commercial simulator by adjusting the relative permeability curves and assigning the values of the rock and fluid properties such as porosity, permeability, and the experimentally determined IFT data. History matching ofthe coreflood model helped us optimize the experiments and was useful in determining the importance of the parameters influencing sweep efficiency in the CWAG process. The effectiveness of the CWAG process in pro- viding enhancement of displacement efficiency is evident in the oil recovery and pressure response observed in the coreflood. The results of sensitivity analysis on CWAG slug patterns show that the alkaline-surfactant-polymer injection is more beneficial after CO2 slug injection due to oil swelling and viscosity reduction. The CO2 slug size analysis shows that there is an optimum CO2 slug size, around 25 % pore volume which leads to a maximum oil recovery in the CWAG process. This study shows that the ultralow IFT system, i.e., IFT equaling 10 2 or 10 3 mN/ m, is a very important parameter in CWAG process since the water blocking effect can be minimized.
文摘This paper presents a novel architecture of combining the linear array of antenna elements, where each antenna element has digitally selectable true time-delays as weights. Use of time-delays for beam-formation inherently makes the phased array network a wideband system. In particular, this technique envisage a new method of sharing antenna elements, by fixed overlapped sub-array architecture, which is able to maintain permissible element spacing to avoid grating lobe in antenna pattern. Moreover, this scheme additionally offers an easier null steering capability to the subarray architecture. This method essentially eliminates the need for intensive computation of complex weight vectors attached to each antenna element.
文摘The Internet has become a means for socialising, shopping, and keeping informed. The true potential of the net is yet to be explored, given the many new electronic devices that can now access it. Online shopping is growing exponentially. Nevertheless, some products are easy to sell online, while others are still better to be sold at the local store. This paper aims to present a model that identifies the attributes that can improve the marketability of product by lnternet： brand, ＂touch and feel＂, scarcity, price, and cost of returns. The model is being tested in 14 bricks and clicks retailers. Interviews with top management evaluate the validity of the attributes considered. All interviewed persons consider all of these attributes like a valid tool to select which products they can sell by Internet. The positive effects are the reduction of unsold goods, the increasing of visited pages in the web site, the reduction of costs due to returns, the increasing of income, and the rationalization of the offer. The information could help retailers adapt their strategies to fit customer＇s needs and attract and retain customers. From the marketing point of view, the knowledge from this study could help to create marketing strategies tailored to respond to online consumer＇s specific requirements and needs.
