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A methodology for damage evaluation of underground tunnels subjected to static loading using numerical modeling 被引量:1
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作者 Shahriyar Heidarzadeh Ali Saeidi 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第6期1993-2005,共13页
We have proposed a methodology to assess the robustness of underground tunnels against potential failure.This involves developing vulnerability functions for various qualities of rock mass and static loading intensiti... We have proposed a methodology to assess the robustness of underground tunnels against potential failure.This involves developing vulnerability functions for various qualities of rock mass and static loading intensities.To account for these variations,we utilized a Monte Carlo Simulation(MCS)technique coupled with the finite difference code FLAC^(3D),to conduct two thousand seven hundred numerical simulations of a horseshoe tunnel located within a rock mass with different geological strength index system(GSIs)and subjected to different states of static loading.To quantify the severity of damage within the rock mass,we selected one stress-based(brittle shear ratio(BSR))and one strain-based failure criterion(plastic damage index(PDI)).Based on these criteria,we then developed fragility curves.Additionally,we used mathematical approximation techniques to produce vulnerability functions that relate the probabilities of various damage states to loading intensities for different quality classes of blocky rock mass.The results indicated that the fragility curves we obtained could accurately depict the evolution of the inner and outer shell damage around the tunnel.Therefore,we have provided engineers with a tool that can predict levels of damages associated with different failure mechanisms based on variations in rock mass quality and in situ stress state.Our method is a numerically developed,multi-variate approach that can aid engineers in making informed decisions about the robustness of underground tunnels. 展开更多
关键词 Fragility curves Underground tunnels Vulnerability functions Brittle damage FLAC3D Numerical modeling
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Oxidation of emerging organic contaminants by in-situ H_(2)O_(2) fenton system 被引量:1
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作者 Yuqin Ni Chuxiang Zhou +1 位作者 Mingyang Xing Yi Zhou 《Green Energy & Environment》 SCIE EI CAS CSCD 2024年第3期417-434,共18页
The existence and risk of emerging organic contaminants(EOCs)have been under consideration and paid much effort to degrade these pollutants.Fenton system is one of the most widely used technologies to solve this probl... The existence and risk of emerging organic contaminants(EOCs)have been under consideration and paid much effort to degrade these pollutants.Fenton system is one of the most widely used technologies to solve this problem.The original Fenton system relies on the hydroxyl radicals produced by Fe(Ⅱ)/H_(2)O_(2) to oxidize the organic contaminants.However,the application of the Fenton system is limited by its low iron cycling efficiency and the high risks of hydrogen peroxide transportation and storage.The introduction of external energy(including light and electricity etc.)can effectively promote the Fe(Ⅲ)/Fe(Ⅱ)cycle and the reduction of oxygen to produce hydrogen peroxide in situ.This review introduces three in-situ Fenton systems,which are electro-Fenton,Photo-Fenton,and chemical reaction.The mechanism,influencing factors,and catalysts of these three in-situ Fenton systems in degrading EOCs are discussed systematically.This review strengthens the understanding of Fenton and in-situ Fenton systems in degradation,offering further insight into the real application of the in-situ Fenton system in the removal of EOCs. 展开更多
关键词 In-situ H_(2)O_(2)production FENTON Emerging organic contaminants Photocatalysis ELECTROCATALYSIS
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Perceptions of Rural Emergency Department Providers regarding Telehealth-Based Care: Perceived Competency, Satisfaction with Care and Tele-ED Patient Disposition
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作者 Roseanne Fairchild Shiaw Fen Ferng Kuo +2 位作者 Stephanie Laws Amanda O’Brien Hicham Rahmouni 《Open Journal of Nursing》 2017年第7期721-733,共13页
Introduction: This study assesses rural providers’ perceptions of their ability to deliver high quality care via telehealth compared to usual care, and whether attending providers perceive that emergency department (... Introduction: This study assesses rural providers’ perceptions of their ability to deliver high quality care via telehealth compared to usual care, and whether attending providers perceive that emergency department (ED) telehealth visits influence clinical reasoning in regard to patient disposition, specifically in tele-behavioral and tele-neurological cases. Methods: A cross-sectional survey was conducted of 134 ED providers (nurses [n = 126] and physicians [n = 8]) who were working in five Midwestern critical access hospitals (response rate 83%). Descriptive, correlational and stepwise regression analyses were employed to evaluate provider perceptions of 1) competency level in telehealth delivery, 2) patient health outcomes, 3) access to continuing education in telehealth, and 4) clinical influence of telehealth visit. Evaluation of preliminary set of N = 100 telehealth cases were assessed for influence of telehealth on clinical reasoning of attending physicians regarding patient disposition. Results: The majority (67%;n = 90) of participants had at least minimal experience with telehealth care delivery, with an average of 1 - 2 visits in teleneurology, and 3 - 4 visits in telebehavioral cases. Providers rated their overall mean competency level in telehealth care delivery as 3.01/5.00 based on a 5 point “novice (1) to expert” (5) scale. Mean scores for providers perceived competency level in 7 evidence-based sub-categories for telehealth care delivery were self-reported as relatively low to mid-range values, ranging from 2.64 - 3.57/5.00. Stepwise linear regression analysis of whether all providers “would recommend telehealth to their family and friends” revealed two predictors for model of best fit (n = 81;p 2 = 0.598): 1) their perceptions of telehealth experience compared to usual care;and 2) perceptions of patient health outcomes with telehealth compared to usual care. Providers rated “neutral” to “very unlikely” that they “would recommend telehealth to family and friends” (2.75/5.00;n = 122;91%). Attending physicians reported that for a majority of cases, telehealth visits influenced patient disposition and transfer decision-making (58.4%), and the influence of telehealth visits on patient disposition was statistically significantly higher for behavioral health cases (p Discussion: This study will be followed on to inform administrators/policy makers about 1) perceived level of competency of providers who implement tele-emergency care, 2) potential importance of telehealth equipment used and teamwork between rural providers and distant specialist, and 3) how use of telehealth may enhance ability of rural ED providers to improve quality of care. Perceived influence of telehealth on patient disposition is reported to be highest for telebehavioral patients. Healthcare educators need to place a priority on addressing provider competencies in telehealth through health professions degree programs and continuing education. Further research is needed to promote application and testing of evidence-based provider competencies in telehealth, and potentially relevant health communication models, to increase providers’ perceived efficacy and competency in telehealth care delivery, thus supporting high quality patient health outcomes. 展开更多
关键词 TELEHEALTH Telemedicine RURAL Emergency Department Critical Access Hospital Provider COMPETENCY Attending Physician PATIENT DISPOSITION Telebehavioral Teleneurological
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Determination of uncertainties of geomechanical parameters of metamorphic rocks using petrographic analyses
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作者 Behzad Dastjerdy Ali Saeidi Shahriyar Heidarzadeh 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第2期345-364,共20页
Geomechanical parameters of intact metamorphic rocks determined from laboratory testing remain highly uncertain because of the great intrinsic variability associated with the degrees of metamorphism.The aim of this pa... Geomechanical parameters of intact metamorphic rocks determined from laboratory testing remain highly uncertain because of the great intrinsic variability associated with the degrees of metamorphism.The aim of this paper is to develop a proper methodology to analyze the uncertainties of geomechanical characteristics by focusing on three domains,i.e.data treatment process,schistosity angle,and mineralogy.First,the variabilities of the geomechanical laboratory data of Westwood Mine(Quebec,Canada)were examined statistically by applying different data treatment techniques,through which the most suitable outlier methods were selected for each parameter using multiple decision-making criteria and engineering judgment.Results indicated that some methods exhibited better performance in identifying the possible outliers,although several others were unsuccessful because of their limitation in large sample size.The well-known boxplot method might not be the best outlier method for most geomechanical parameters because its calculated confidence range was not acceptable according to engineering judgment.However,several approaches,including adjusted boxplot,2MADe,and 2SD,worked very well in the detection of true outliers.Also,the statistical tests indicate that the best-fitting probability distribution function for geomechanical intact parameters might not be the normal distribution,unlike what is assumed in most geomechanical studies.Moreover,the negative effects of schistosity angle on the uniaxial compressive strength(UCS)variabilities were reduced by excluding the samples within a specific angle range where the UCS data present the highest variation.Finally,a petrographic analysis was conducted to assess the associated uncertainties such that a logical link was found between the dispersion and the variabilities of hard and soft minerals. 展开更多
关键词 Intact rock parameters Natural variabilities Outlier detection methods UNCERTAINTIES Westwood mine MINERALOGY
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A review of understanding electrocatalytic reactions in energy conversion and energy storage systems via scanning electrochemical microscopy
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作者 Jihye Park Jong Hwan Lim +4 位作者 Jin-Hyuk Kang Jiheon Lim Ho Won Jang Hosun Shin Sun Hwa Park 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第4期155-177,共23页
To address climate change and promote environmental sustainability,electrochemical energy conversion and storage systems emerge as promising alternative to fossil fuels,catering to the escalating demand for energy.Ach... To address climate change and promote environmental sustainability,electrochemical energy conversion and storage systems emerge as promising alternative to fossil fuels,catering to the escalating demand for energy.Achieving optimal energy efficiency and cost competitiveness in these systems requires the strategic design of electrocatalysts,coupled with a thorough comprehension of the underlying mechanisms and degradation behavior occurring during the electrocatalysis processes.Scanning electrochemical microscopy(SECM),an analytical technique for studying surface electrochemically,stands out as a powerful tool offering electrochemical insights.It possesses remarkable spatiotemporal resolution,enabling the visualization of the localized electrochemical activity and surface topography.This review compiles crucial research findings and recent breakthroughs in electrocatalytic processes utilizing the SECM methodology,specifically focusing on applications in electrolysis,fuel cells,and metal–oxygen batteries within the realm of energy conversion and storage systems.Commencing with an overview of each energy system,the review introduces the fundamental principles of SECM,and aiming to provide new perspectives and broadening the scope of applied research by describing the major research categories within SECM. 展开更多
关键词 Scanning electrochemical microscopy ELECTROCATALYST ELECTROCATALYSIS Water splitting Fuel cell Metal-oxygen battery
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An Integrated Analysis of Yield Prediction Models:A Comprehensive Review of Advancements and Challenges
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作者 Nidhi Parashar Prashant Johri +2 位作者 Arfat Ahmad Khan Nitin Gaur Seifedine Kadry 《Computers, Materials & Continua》 SCIE EI 2024年第7期389-425,共37页
The growing global requirement for food and the need for sustainable farming in an era of a changing climate and scarce resources have inspired substantial crop yield prediction research.Deep learning(DL)and machine l... The growing global requirement for food and the need for sustainable farming in an era of a changing climate and scarce resources have inspired substantial crop yield prediction research.Deep learning(DL)and machine learning(ML)models effectively deal with such challenges.This research paper comprehensively analyses recent advancements in crop yield prediction from January 2016 to March 2024.In addition,it analyses the effectiveness of various input parameters considered in crop yield prediction models.We conducted an in-depth search and gathered studies that employed crop modeling and AI-based methods to predict crop yield.The total number of articles reviewed for crop yield prediction using ML,meta-modeling(Crop models coupled with ML/DL),and DL-based prediction models and input parameter selection is 125.We conduct the research by setting up five objectives for this research and discussing them after analyzing the selected research papers.Each study is assessed based on the crop type,input parameters employed for prediction,the modeling techniques adopted,and the evaluation metrics used for estimatingmodel performance.We also discuss the ethical and social impacts of AI on agriculture.However,various approaches presented in the scientific literature have delivered impressive predictions,they are complicateddue to intricate,multifactorial influences oncropgrowthand theneed for accuratedata-driven models.Therefore,thorough research is required to deal with challenges in predicting agricultural output. 展开更多
关键词 Machine learning crop yield prediction deep learning remote sensing long short-term memory time series prediction systematic literature review
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Towards high-performance and robust anion exchange membranes(AEMs)for water electrolysis:Super-acid-catalyzed synthesis of AEMs
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作者 Geun Woong Ryoo Sun Hwa Park +3 位作者 Ki Chang Kwon Jong Hun Kang Ho Won Jang Min Sang Kwon 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第6期478-510,I0012,共34页
The increasing demand for hydrogen energy to address environmental issues and achieve carbon neutrality has elevated interest in green hydrogen production,which does not rely on fossil fuels.Among various hydrogen pro... The increasing demand for hydrogen energy to address environmental issues and achieve carbon neutrality has elevated interest in green hydrogen production,which does not rely on fossil fuels.Among various hydrogen production technologies,anion exchange membrane water electrolyzer(AEMWE)has emerged as a next-generation technology known for its high hydrogen production efficiency and its ability to use non-metal catalysts.However,this technology faces significant challenges,particularly in terms of the membrane durability and low ionic conductivity.To address these challenges,research efforts have focused on developing membranes with a new backbone structure and anion exchange groups to enhance durability and ionic conductivity.Notably,the super-acid-catalyzed condensation(SACC)synthesis method stands out due to its user convenience,the ability to create high molecular weight(MW)polymers,and the use of oxygen-tolerant organic catalysts.Although the synthesis of anion exchange membranes(AEMs)using the SACC method began in 2015,and despite growing interest in this synthesis approach,there remains a scarcity of review papers focusing on AEMs synthesized using the SACC method.The review covers the basics of SACC synthesis,presents various polymers synthesized using this method,and summarizes the development of these polymers,particularly their building blocks including aryl,ketone,and anion exchange groups.We systematically describe the effects of changes in the molecular structure of each polymer component,conducted by various research groups,on the mechanical properties,conductivity,and operational stability of the membrane.This review will provide insights into the development of AEMs with superior performance and operational stability suitable for water electrolysis applications. 展开更多
关键词 Green hydrogen production Water electrolysis Anion exchange membrane water electrolyzer(AEMWE) Anion exchange membranes(AEMs) Super-acid-catalyzed condensation(SACC)
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A NovelMethod for Determining Tourism Carrying Capacity in a Decision-Making Context Using q−Rung Orthopair Fuzzy Hypersoft Environment
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作者 Salma Khan Muhammad Gulistan +2 位作者 NasreenKausar Seifedine Kadry Jungeun Kim 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第2期1951-1979,共29页
Tourism is a popular activity that allows individuals to escape their daily routines and explore new destinations for various reasons,including leisure,pleasure,or business.A recent study has proposed a unique mathema... Tourism is a popular activity that allows individuals to escape their daily routines and explore new destinations for various reasons,including leisure,pleasure,or business.A recent study has proposed a unique mathematical concept called a q−Rung orthopair fuzzy hypersoft set(q−ROFHS)to enhance the formal representation of human thought processes and evaluate tourism carrying capacity.This approach can capture the imprecision and ambiguity often present in human perception.With the advanced mathematical tools in this field,the study has also incorporated the Einstein aggregation operator and score function into the q−ROFHS values to supportmultiattribute decision-making algorithms.By implementing this technique,effective plans can be developed for social and economic development while avoiding detrimental effects such as overcrowding or environmental damage caused by tourism.A case study of selected tourism carrying capacity will demonstrate the proposed methodology. 展开更多
关键词 q−Rung orthopair fuzzy hypersoft set DECISION-MAKING tourism carrying capacity aggregation operator
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Novelty of Different Distance Approach for Multi-Criteria Decision-Making Challenges Using q-Rung Vague Sets
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作者 Murugan Palanikumar Nasreen Kausar +3 位作者 Dragan Pamucar Seifedine Kadry Chomyong Kim Yunyoung Nam 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第6期3353-3385,共33页
In this article,multiple attribute decision-making problems are solved using the vague normal set(VNS).It is possible to generalize the vague set(VS)and q-rung fuzzy set(FS)into the q-rung vague set(VS).A log q-rung n... In this article,multiple attribute decision-making problems are solved using the vague normal set(VNS).It is possible to generalize the vague set(VS)and q-rung fuzzy set(FS)into the q-rung vague set(VS).A log q-rung normal vague weighted averaging(log q-rung NVWA),a log q-rung normal vague weighted geometric(log q-rung NVWG),a log generalized q-rung normal vague weighted averaging(log Gq-rung NVWA),and a log generalized q-rungnormal vagueweightedgeometric(logGq-rungNVWG)operator are discussed in this article.Adescription is provided of the scoring function,accuracy function and operational laws of the log q-rung VS.The algorithms underlying these functions are also described.A numerical example is provided to extend the Euclidean distance and the Humming distance.Additionally,idempotency,boundedness,commutativity,and monotonicity of the log q-rung VS are examined as they facilitate recognizing the optimal alternative more quickly and help clarify conceptualization.We chose five anemia patients with four types of symptoms including seizures,emotional shock or hysteria,brain cause,and high fever,who had either retrograde amnesia,anterograde amnesia,transient global amnesia,post-traumatic amnesia,or infantile amnesia.Natural numbers q are used to express the results of the models.To demonstrate the effectiveness and accuracy of the models we are investigating,we compare several existing models with those that have been developed. 展开更多
关键词 Vague set aggregating operators euclidean distance hamming distance decision making
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A deep learning fusion model for accurate classification of brain tumours in Magnetic Resonance images
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作者 Nechirvan Asaad Zebari Chira Nadheef Mohammed +8 位作者 Dilovan Asaad Zebari Mazin Abed Mohammed Diyar Qader Zeebaree Haydar Abdulameer Marhoon Karrar Hameed Abdulkareem Seifedine Kadry Wattana Viriyasitavat Jan Nedoma Radek Martinek 《CAAI Transactions on Intelligence Technology》 SCIE EI 2024年第4期790-804,共15页
Detecting brain tumours is complex due to the natural variation in their location, shape, and intensity in images. While having accurate detection and segmentation of brain tumours would be beneficial, current methods... Detecting brain tumours is complex due to the natural variation in their location, shape, and intensity in images. While having accurate detection and segmentation of brain tumours would be beneficial, current methods still need to solve this problem despite the numerous available approaches. Precise analysis of Magnetic Resonance Imaging (MRI) is crucial for detecting, segmenting, and classifying brain tumours in medical diagnostics. Magnetic Resonance Imaging is a vital component in medical diagnosis, and it requires precise, efficient, careful, efficient, and reliable image analysis techniques. The authors developed a Deep Learning (DL) fusion model to classify brain tumours reliably. Deep Learning models require large amounts of training data to achieve good results, so the researchers utilised data augmentation techniques to increase the dataset size for training models. VGG16, ResNet50, and convolutional deep belief networks networks extracted deep features from MRI images. Softmax was used as the classifier, and the training set was supplemented with intentionally created MRI images of brain tumours in addition to the genuine ones. The features of two DL models were combined in the proposed model to generate a fusion model, which significantly increased classification accuracy. An openly accessible dataset from the internet was used to test the model's performance, and the experimental results showed that the proposed fusion model achieved a classification accuracy of 98.98%. Finally, the results were compared with existing methods, and the proposed model outperformed them significantly. 展开更多
关键词 brain tumour deep learning feature fusion model MRI images multi‐classification
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An Assessment on the Impact of Technological Addiction on Workplace Productivity: Case of the Public Sector in Zimbabwe
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作者 Nelson Matanana Prosper Tafadzwa Denhere +3 位作者 David Chibhoyi Allen Mutumwa Sithole Morgen Noah Ariel Mutongoreni 《World Journal of Engineering and Technology》 2024年第3期635-650,共16页
With the increasing integration of technology in modern workplaces, concerns have emerged regarding the addictive nature of technology and its potential consequences on employee productivity. This research aims to inv... With the increasing integration of technology in modern workplaces, concerns have emerged regarding the addictive nature of technology and its potential consequences on employee productivity. This research aims to investigate the impact of technological addiction on workplace productivity within the public sector of Zimbabwe. The study employed a mixed-methods approach, combining surveys, interviews, and a case study analysis, to examine the prevalence and effects of technological addiction in affecting productivity in the public sector of Zimbabwe. The findings indicate that excessive use of social media, and other digital distractions is a growing concern in the public sector, leading to decreased focus, missed deadlines, and strained teamwork. Factors such as unrestricted internet access, lack of clear usage policies, and inadequate self-regulation contribute to the problem The research outcomes also highlight the need for awareness and interventions to address social media addiction in the workplace, promote healthier technology use, and uphold productivity and employee well-being. 展开更多
关键词 Technology Addiction Workplace Productivity TECHNOLOGY Public Sector Zimbabwe
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Comprehensive Assessment of Anxiolytic Properties in 4-HPAA Derivatives: Bridging in Vivo Validation and Molecular Docking Analyses
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作者 Kawthar Alhussieni Rami Ayoub +7 位作者 Jamal Jilani Qais Jarrar Othman Alhussinei Vetriselvan Subramaniyan Esra Nasraldin Khalil Sharafaldin Harshini Muruganantham Jureerat Kijsomporn Ling Shing Wong 《Open Journal of Medicinal Chemistry》 2024年第3期29-44,共16页
Anxiety is a significant mental health issue that substantially affects an individual’s quality of life. Feelings of uneasiness, irritability, and sleep disturbances characterize it. 4-Hydroxyphenyl acetic acid (4-HP... Anxiety is a significant mental health issue that substantially affects an individual’s quality of life. Feelings of uneasiness, irritability, and sleep disturbances characterize it. 4-Hydroxyphenyl acetic acid (4-HPAA) is identified in brain cells as a physiological byproduct of tyramine. This study hypothesizes that 4-HPAA may regulate anxiety due to its anxiolytic properties, acting as a modulator of the GABAergic system, which plays a crucial role in the pathophysiology of anxiety disorders. Our study aims to enhance the anxiolytic effects of 4-HPAA through chemical modification to improve its pharmacokinetic properties. Three derivatives, namely Isopropyl-4-hydroxy-[phenyl] acetate (IHPA), Isopropyl-4-hydroxy-[phenyl] acetate (MPAA), and 4-methoxyphenyl acetate (MPHA), have been synthesized from 4-HPAA. This assessment will use well-established animal models, specifically the Elevated Plus-Maze (EPM) and Zero Maze (EZM) tests, selected for their validity in replicating anxiety-like symptoms in animals. Chronic caffeine administration via drinking water (0.3 g/l for 14 days) was employed to induce an anxiety state for testing purposes. IHPA and MPAA demonstrated significant anxiolyticactivity when tested in the EPM and EZM experiments. Molecular docking simulations using AutoDock Vina indicated that 4-HPAA derivatives had docking scores ranging from −5.8 to −4.8 kcal/mol, compared to the standard anxiolytic medication Diazepam, which scored −7.1 kcal/mol. These scores suggest a potential for 4-HPAA derivatives to interact effectively with the Gamma-aminobutyric acid (GABA_A) receptor. In conclusion, our in vivo and in silico analyses indicate a promising anxiolytic potential for 4-HPAA derivatives. 展开更多
关键词 ANXIOLYTICS 4-HPAA Molecular Docking Elevated Plus-Maze Zero Maze Tests
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A novel solution treatment and aging for powder bed fusion-laser beam Ti-6Al-2Sn-4Zr-6Mo alloy:Microstructural and mechanical characterization
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作者 Gianluca Pirro Alessandra Martucci +2 位作者 Alessandro Morri Mariangela Lombardi Lorella Ceschini 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS 2025年第2期414-424,共11页
Ti-6Al-4Zr-2Sn-6Mo alloy is one of the most recent titanium alloys processed using powder bed fusion-laser beam(PBF-LB)technology.This alloy has the potential to replace Ti-6Al-4V in automotive and aerospace applicati... Ti-6Al-4Zr-2Sn-6Mo alloy is one of the most recent titanium alloys processed using powder bed fusion-laser beam(PBF-LB)technology.This alloy has the potential to replace Ti-6Al-4V in automotive and aerospace applications,given its superior mechanical properties,which are approximately 10%higher in terms of ultimate tensile strength(UTS)and yield strength after appropriate heat treatment.In as-built conditions,the alloy is characterized by the presence of soft orthorhombicα″martensite,necessitating a postprocessing heat treatment to decompose this phase and enhance the mechanical properties of the alloy.Usually,PBFed Ti6246 components undergo an annealing process that transforms theα″martensite into anα-βlamellar microstructure.The primary objective of this research was to develop a solution treatment and aging(STA)heat treatment tailored to the unique microstructure produced by the additive manufacturing process to achieve an ultrafine bilamellar microstructure reinforced by precipitation hardening.This study investigated the effects of various solution temperatures in theα-βfield(ranging from 800 to 875℃),cooling media(air and water),and aging time to determine the optimal heat treatment parameters for achieving the desired bilamellar microstructure.For each heat treatment condition,differentα-βmicrostructures were found,varying in terms of theα/βratio and the size of the primaryα-phase lamellae.Particular attention was given to how these factors were influenced by increases in solution temperature and how microhardness correlated with the percentage of the metastableβphase present after quenching.Tensile tests were performed on samples subjected to the most promising heat treatment parameters.A comparison with literature data revealed that the optimized STA treatment enhanced hardness and UTS by13%and 23%,respectively,compared with those of the annealed alloy.Fracture surface analyses were conducted to investigate fracture mechanisms. 展开更多
关键词 powder bed fusion-laser beam titanium alloys heat treatments mechanical properties fractographic analysis
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Evaluation of the effect of geometrical parameters on stope probability of failure in the open stoping method using numerical modeling 被引量:12
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作者 Shahriyar Heidarzadeh Ali Saeidi Alain Rouleau 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2019年第3期399-408,共10页
Stress-induced failure is among the most common causes of instability in Canadian deep underground mines.Open stoping is the most widely practiced underground excavation method in these mines,and creates large stopes ... Stress-induced failure is among the most common causes of instability in Canadian deep underground mines.Open stoping is the most widely practiced underground excavation method in these mines,and creates large stopes which are subjected to stress-induced failure.The probability of failure(POF)depends on many factors,of which the geometry of an open stope is especially important.In this study,a methodology is proposed to assess the effect of stope geometrical parameters on the POF,using numerical modelling.Different ranges for each input parameter are defined according to previous surveys on open stope geometry in a number of Canadian underground mines.A Monte-Carlo simulation technique is combined with the finite difference code FLAC3D,to generate model realizations containing stopes with different geometrical features.The probability of failure(POF)for different categories of stope geometry,is calculated by considering two modes of failure;relaxation-related gravity driven(tensile)failure and rock mass brittle failure.The individual and interactive effects of stope geometrical parameters on the POF,are analyzed using a general multi-level factorial design.Finally,mathematical optimization techniques are employed to estimate the most stable stope conditions,by determining the optimal ranges for each stope’s geometrical parameter. 展开更多
关键词 STOPE stability STOPE GEOMETRICAL parameters PROBABILITY of failure General FACTORIAL design Numerical modeling Sublevel OPEN STOPING
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Role of Hox genes in stem cell differentiation 被引量:10
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作者 Anne Seifert David F Werheid +1 位作者 Silvana M Knapp Edda Tobiasch 《World Journal of Stem Cells》 SCIE CAS 2015年第3期583-595,共13页
Hox genes are an evolutionary highly conserved gene family. They determine the anterior-posterior body axis in bilateral organisms and influence the developmental fate of cells. Embryonic stem cells are usually devoid... Hox genes are an evolutionary highly conserved gene family. They determine the anterior-posterior body axis in bilateral organisms and influence the developmental fate of cells. Embryonic stem cells are usually devoidof any Hox gene expression, but these transcription factors are activated in varying spatial and temporal patterns defining the development of various body regions. In the adult body, Hox genes are among others responsible for driving the differentiation of tissue stem cells towards their respective lineages in order to repair and maintain the correct function of tissues and organs. Due to their involvement in the embryonic and adult body, they have been suggested to be useable for improving stem cell differentiations in vitro and in vivo. In many studies Hox genes have been found as driving factors in stem cell differentiation towards adipogenesis, in lineages involved in bone and joint formation, mainly chondrogenesis and osteogenesis, in cardiovascular lineages including endothelial and smooth muscle cell differentiations, and in neurogenesis. As life expectancy is rising, the demand for tissue reconstruction continues to increase. Stem cells have become an increasingly popular choice for creating therapies in regenerative medicine due to their self-renewal and differentiation potential. Especially mesenchymal stem cells are used more and more frequently due to their easy handling and accessibility, combined with a low tumorgenicity and little ethical concerns. This review therefore intends to summarize to date known correlations between natural Hox gene expression patterns in body tissues and during the differentiation of various stem cells towards their respective lineages with a major focus on mesenchymal stem cell differentiations. This overview shall help to understand the complex interactions of Hox genes and differentiation processes all over the body as well as in vitro for further improvement of stem cell treatments in future regenerative medicine approaches. 展开更多
关键词 Genes HOMEOBOX Stem CELLS Asymmetriccell division MESENCHYMAL STROMAL CELLS Growth Development Regeneration PATTERNING Cell LINEAGE
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Adaptive Maneuvering Frequency Method of Current Statistical Model 被引量:13
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作者 Wei Sun Yongjian Yang 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2017年第1期154-160,共7页
Current statistical model(CSM) has a good performance in maneuvering target tracking. However, the fixed maneuvering frequency will deteriorate the tracking results, such as a serious dynamic delay, a slowly convergin... Current statistical model(CSM) has a good performance in maneuvering target tracking. However, the fixed maneuvering frequency will deteriorate the tracking results, such as a serious dynamic delay, a slowly converging speedy and a limited precision when using Kalman filter(KF) algorithm. In this study, a new current statistical model and a new Kalman filter are proposed to improve the performance of maneuvering target tracking. The new model which employs innovation dominated subjection function to adaptively adjust maneuvering frequency has a better performance in step maneuvering target tracking, while a fluctuant phenomenon appears. As far as this problem is concerned, a new adaptive fading Kalman filter is proposed as well. In the new Kalman filter, the prediction values are amended in time by setting judgment and amendment rules,so that tracking precision and fluctuant phenomenon of the new current statistical model are improved. The results of simulation indicate the effectiveness of the new algorithm and the practical guiding significance. 展开更多
关键词 Current statistical model(CSM) maneuvering target tracking adaptive fading Kalman filter(AFKF)
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Characteristics of gas evolution profiles during coal pyrolysis and its relation with the variation of functional groups 被引量:8
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作者 Lu Zhang Shichao Qi +3 位作者 Norihiro Takeda Shinji Kudo Junichiro Hayashi Koyo Norinaga 《International Journal of Coal Science & Technology》 EI 2018年第4期452-463,共12页
Strict relation between the substituents or functional groups attached to the coal macromolecules and the generation of the volatile products, e.g., CH4 H2O, CO, CO2, etc., during the coal pyrolysis is an important bu... Strict relation between the substituents or functional groups attached to the coal macromolecules and the generation of the volatile products, e.g., CH4 H2O, CO, CO2, etc., during the coal pyrolysis is an important but confusing subject. In this paper, quadrupole mass spectronletry, gas chromatography, and ^l3C nuclear magnetic resonance are applied to real-time monitoring the formations of volatile products, off-line quantitative determination of the total products from the pyrolysis of a sub-bituminous coal (SC), and the changes of diverse substitents in the SC along with coke foamation, respectively. These measurements are also performed for the pyrolysis of a caking coal to contrast SC. The qualitative and quantitative data reveal that, during coal pyrolysis, the functional groups related with the formation of CO, i.e., ether, carbonyl, and anhydride, can directly gen erate CO via bond breaking, or take a detour of the formation of other intermediates via condensation and recombination firstly. Moreover, the formations of CO2 and CH4 are related to the direct removal of -COO- and -CH3,respectively. 展开更多
关键词 Light gas evolution CARBONIZATION QMS GC ^13C NMR
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GC-MS analysis of volatile compounds of Perilla frutescens Britton var. Japonica accessions: morphological and seasonal variability 被引量:7
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作者 Bimal Kumar Ghimire Ji Hye Yoo +1 位作者 Chang Yeon Yu Ill-Min Chung 《Asian Pacific Journal of Tropical Medicine》 SCIE CAS 2017年第7期705-714,共10页
Objective: To investigate the composition of volatile compounds in the different accessions of Perilla frutescens(P. frutescens) collected from various habitats of China and Japan. Methods: In the present study, the e... Objective: To investigate the composition of volatile compounds in the different accessions of Perilla frutescens(P. frutescens) collected from various habitats of China and Japan. Methods: In the present study, the essential oil from the leaves of P. frutescens cultivars from China and Japan was extracted by hydro-distillation and the chemical composition and concentration of the volatile components present in the oils were determined by gas chromatography–mass spectrometry(GC–MS) analysis. Results: Among the volatile components, the major proportion was of perilla ketone, which was followed by elemicin and beta-caryophyllene in the Chinese Perilla cultivars. The main component in the oil extracted from the Japanese accessions was myristicin, which was followed by perilla ketone and beta-caryophyllene. We could distinguish seven chemotypes, namely the perilla ketone(PK) type, perilla ketone, myristicin(PM) type, perilla ketone, unknown(PU) type, perilla ketone, beta-caryophyllene, myristicine(PB) type, perilla ketone, myristicin, unknown(PMU) type, perilla ketone, elemicine, myristicin, beta-caryophyllene(PEMB) type, and the perilla ketone, limonene, betacryophyllene, myristicin(L) type. Most of the accessions possessed higher essential oil content before the flowering time than at the flowering stage. The average plant height, leaf length, leaf width of the Chinese accessions was higher than those of the Japanese accessions. Conclusion:The results revealed that the harvest time and geographical origin caused polymorphisms in the essential oil composition and morphological traits in the Perilla accessions originating from China and Japan. Therefore, these chemotypes with desirable characters might be useful for industrial exploitation and for determining the harvest time. 展开更多
关键词 Perilla frutescens Essential oil GC–MS analysis Morphological character Harvesting time
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Effect of different quenching processes following solid-solution treatment on properties and precipitation behaviors of 7050 alloy 被引量:8
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作者 Lei KANG Gang ZHAO +2 位作者 Guang-dong WANG Kun LIU Ni TIAN 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2018年第11期2163-2173,共11页
The effects of quenching in different ways following solid-solution treatment on properties and precipitation behaviors of7050 alloy were investigated by transmission electron microscopy (TEM), scanning electron mic... The effects of quenching in different ways following solid-solution treatment on properties and precipitation behaviors of7050 alloy were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), selected areaelectron diffraction (SAED), hardness and electrical conductivity tests. Results show that after quenching in different ways, electricalconductivity of the alloy decreases rapidly in the first 48 h of natural aging. The electrical conductivity of 7050 alloy in natural agingstate is determined by the size and density of GP zones, and the size of GP zones is the main factor. After natural aging for 70 d, thesize of GP zones is 1.8-2.6 nm in matrix of the immersion quenched sample and it is 1.4-1.8 nm in matrix of both water mist andforced air quenched samples. After natural and artificial peak aging, the hardness of the water mist quenched sample is HV 193.6 andits electrical conductivity is 30.5% (IACS) which are both higher than those of the immersion quenched sample. Therefore, watermist quenching is an ideal quenching method for 7050 alloy sheets after solid-solution treatment. 展开更多
关键词 7050 aluminum alloy quenching method precipitation behavior electrical conductivity nucleation site
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A systematic review of active video games on rehabilitative outcomes among older patients 被引量:7
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作者 Nan Zeng Zachary Pope +1 位作者 Jung Eun Lee Zan Gao 《Journal of Sport and Health Science》 SCIE 2017年第1期33-43,共11页
Background: Although current research supports the use of active video games(AVGs) in rehabilitation, the evidence has yet to be systematically reviewed or synthesized. The current project systematically reviewed lite... Background: Although current research supports the use of active video games(AVGs) in rehabilitation, the evidence has yet to be systematically reviewed or synthesized. The current project systematically reviewed literature, summarized findings, and evaluated the effectiveness of AVGs as a therapeutic tool in improving physical, psychological, and cognitive rehabilitative outcomes among older adults with chronic diseases.Methods: Seven databases(Academic Search Complete, Communication & Mass Media Complete, ERIC, Psyc INFO, Pub Med, SPORTDiscus,and Medline) were searched for studies that evaluated the effectiveness of AVG-based rehabilitation among older patients. The initial search yielded 946 articles; after evaluating against inclusion criteria and removing duplicates, 19 studies of AVG-based rehabilitation remained.Results: Most studies were quasi-experimental in design, with physical functioning the primary outcome investigated with regard to the use of AVGs in rehabilitation. Overall, 9 studies found significant improvements for all study outcomes, whereas 9 studies were mixed, with significant improvements on several study outcomes but no effects observed on other outcomes after AVG-based treatments. One study failed to find any benefits of AVG-based rehabilitation.Conclusion: Findings indicate AVGs have potential in rehabilitation for older patients, with several randomized clinical trials reporting positive effects on rehabilitative outcomes. However, existing evidence is insufficient to support the advantages of AVGs over standard therapy. Given the limited number of studies and concerns with study design quality, more research is warranted to make more definitive conclusions regarding the ability of AVGs to improve rehabilitative outcomes in older patients. 展开更多
关键词 BALANCE DEPRESSION ENJOYMENT Exergaming Physical functioning Quality of life
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