Cloud computing plays a significant role in modern information technology, providing organizations with numerous benefits, including flexibility, scalability, and cost-efficiency. However, it has become essential for ...Cloud computing plays a significant role in modern information technology, providing organizations with numerous benefits, including flexibility, scalability, and cost-efficiency. However, it has become essential for organizations to ensure the security of their applications, data, and cloud-based networks to use cloud services effectively. This systematic literature review aims to determine the latest information regarding cloud computing security, with a specific emphasis on threats and mitigation strategies. Additionally, it highlights some common threats related to cloud computing security, such as distributed denial-of-service (DDoS) attacks, account hijacking, malware attacks, and data breaches. This research also explores some mitigation strategies, including security awareness training, vulnerability management, security information and event management (SIEM), identity and access management (IAM), and encryption techniques. It discusses emerging trends in cloud security, such as integrating artificial intelligence (AI) and machine learning (ML), serverless computing, and containerization, as well as the effectiveness of the shared responsibility model and its related challenges. The importance of user awareness and the impact of emerging technologies on cloud security have also been discussed in detail to mitigate security risks. A literature review of previous research and scholarly articles has also been conducted to provide insights regarding cloud computing security. It shows the need for continuous research and innovation to address emerging threats and maintain a security-conscious culture in the company.展开更多
Objective:To investigate the safety hazards in nursing and explore mitigation strategies for elderly patients in the endocrinology department.Methods:A total of 240 bedridden elderly patients from February 2021 to Jan...Objective:To investigate the safety hazards in nursing and explore mitigation strategies for elderly patients in the endocrinology department.Methods:A total of 240 bedridden elderly patients from February 2021 to January 2023 were recruited and divided into two groups using the random number table method.The control group(n=120)received conventional nursing care,and the observation group(n=120)received personalized nursing care.Patients’quality of life,the incidence rate of pressure sores,and patient satisfaction with nursing care were observed and analyzed.Results:The incidence of pressure ulcers in the observation group was significantly lower at 17.50%compared to 30.00%in the control group(P<0.05).Quality of life in the observation group was significantly higher than that in the control group(P<0.05).The satisfaction rate in the observation group was significantly higher at 93.33%compared to 84.17%in the control group(P<0.05).Conclusion:These findings emphasize that only through the implementation of scientific and rational nursing measures can effectively reduce nursing risks,enhance therapeutic outcomes,and improve the quality of life for elderly patients.展开更多
The complex compositions and large shrinkage of concrete,as well as the strong constraints of the structures,often lead to prominent shrinkage cracking problems in modem concrete structures.This paper first introduces...The complex compositions and large shrinkage of concrete,as well as the strong constraints of the structures,often lead to prominent shrinkage cracking problems in modem concrete structures.This paper first introduces a multi-field(hydro-thermo-hygro-constraint)coupling model with the hydration degree of cementitious materials as the basic state parameter to estimate the shrinkage cracking risk of hardening concrete under coupling effects.Second,three new key technologies are illustrated:temperature rise inhibition,full-stage shrinkage compensation,and shrinkage reduction technologies.These technologies can efficiently reduce the thermal,autogenous,and drying shrinkages of concrete.There after,a design process based on the theoretical model and key technologies is proposed to control thecracking risk index below the threshold value.Finally,two engineering application examples are provided that demonstrate that concrete shrinkage cracking can be significantly mitigated by adopting the proposed methods and technologies.展开更多
A low-frequency debris flow took place in the north coastal range of Venezuela on Dec. 16, 1999, and scientists all over the world paid attention to this catastrophe. Four characteristics of low-frequency debris hazar...A low-frequency debris flow took place in the north coastal range of Venezuela on Dec. 16, 1999, and scientists all over the world paid attention to this catastrophe. Four characteristics of low-frequency debris hazard are discussed: long return period and extreme catastrophe, special rare triggering factors, difficulty in distinguishing and a series of small hazards subsequent to the catastrophe. Different measures, such as preventing, forecast - warning, engineering, can be used for mitigating and controlling the catastrophe. In engineering practice, it is a key that large silt-trap dams are used to control rare large debris flow. A kind of low dam with cheap cost can be used to replace high dam in developing countries. A planning for controlling debris flow hazard in Cerro Grande stream of Venezuela is presented at the end of this paper.展开更多
The accelerated degradation in the front ceils of a polymer electrolyte membrane fuel cell(PEMFC) stack seriously reduces the reliability and durability of the whole stack. Most researches only focus on the size and...The accelerated degradation in the front ceils of a polymer electrolyte membrane fuel cell(PEMFC) stack seriously reduces the reliability and durability of the whole stack. Most researches only focus on the size and configuration of the gas intake manifold, which may lead to the maldistribution of flow and pressure. In order to find out the mechanisms of the accelerated degradation in the front cells, an extensive program of experimental and simulation work is initiated and the results are reported. It is found that after long-term lifetime tests the accelerated degradation in the front cells occurs in all three fuel cell stacks with different flow-fields under the U-type feed configuration. Compared with the rear cells of the stack, the voltage of the front cells is much lower at the same current densities and the membrane electrode assembly(MEA) has smaller active area, more catalyst particle agglomeration and higher ohmic impedance. For further investigation, a series of three dimensional isothermal numerical models are built to investigate the degradation mechanisms based on the experimental data. The simulation results reveal that the dry working condition of the membrane and the effect of high-speed gas scouting the MEA are the main causes of the accelerated degradation in the front cells of a PEM fuel cell stack under the U-type feed configuration. Several mitigation strategies that would mitigate these phenomena are presented: removing cells that have failed and replacing them with those of the same aging condition as the average of the stack; choosing a Z-type feed pattern instead of a U-type one; putting several air flow-field plates without MEA in the front of the stack; or exchanging the gas inlet and outlet alternately at a certain interval. This paper specifies the causes of the accelerated degradation in the front cells and provides the mitigation strategies.展开更多
This study proposes an approach that considers mitigation strategies in predicting landslide susceptibility through machine learning(ML)and geographic information system(GIS)techniques.ML models,such as random forest(...This study proposes an approach that considers mitigation strategies in predicting landslide susceptibility through machine learning(ML)and geographic information system(GIS)techniques.ML models,such as random forest(RF),logistic regression(LR),and support vector classification(SVC)are incorporated into GIS to predict landslide susceptibilities in Hong Kong.To consider the effect of mitigation strategies on landslide susceptibility,non-landslide samples were produced in the upgraded area and added to randomly created samples to serve as ML models in training datasets.Two scenarios were created to compare and demonstrate the efficiency of the proposed approach;Scenario I does not considering landslide control while Scenario II considers mitigation strategies for landslide control.The largest landslide susceptibilities are 0.967(from RF),followed by 0.936(from LR)and 0.902(from SVC)in Scenario II;in Scenario I,they are 0.986(from RF),0.955(from LR)and 0.947(from SVC).This proves that the ML models considering mitigation strategies can decrease the current landslide susceptibilities.The comparison between the different ML models shows that RF performed better than LR and SVC,and provides the best prediction of the spatial distribution of landslide susceptibilities.展开更多
The combined effects of global warming and the urban heat islands exacerbate the risk of urban heat stress. It is crucial to implement effective cooling measures in urban areas to improve the comfort of the thermal en...The combined effects of global warming and the urban heat islands exacerbate the risk of urban heat stress. It is crucial to implement effective cooling measures in urban areas to improve the comfort of the thermal environment. In this study, the Weather Research and Forecasting Model(WRF), coupled with a single-layer Urban Canopy Model(UCM), was used to study the impact of heat mitigation strategies. In addition, a 5-km resolution land-cover dataset for China(ChinaLC), which is based on satellite remote sensing data, was adjusted and used, and 18 groups of numerical experiments were designed, to increase the albedo and vegetation fraction of roof/ground parameters. The experiments were conducted for four heatwave events that occurred in the summer of 2013 in the Yangtze River Delta urban agglomeration of China. The simulated results demonstrated that, for the single roof/ground schemes, the mitigation effects were directly proportional to the albedo and greening. Among all the experimental schemes, the superposed schemes presented better cooling effects. For the ground greening scheme, with similar net radiation flux and latent heat flux, its storage heat was lower than that of the roof greening scheme, resulting in more energy flux into the atmosphere, and its daytime cooling effect was not as good as that of the roof greening scheme. In terms of human thermal comfort(HTC), the improvement achieved by the ground greening scheme was better than any other single roof/ground schemes, because the increase in the relative humidity was small. The comprehensive evaluation of the mitigation effects of different schemes on the thermal environment presented in this paper provides a theoretical basis for improving the urban environment through rational urban planning and construction.展开更多
Staphylococcus aureus(S. aureus) is a common pathogenic bacterium in animal husbandry that can cause diseases such as mastitis, skin infections, arthritis, and other ailments. The formation of biofilms threatens and e...Staphylococcus aureus(S. aureus) is a common pathogenic bacterium in animal husbandry that can cause diseases such as mastitis, skin infections, arthritis, and other ailments. The formation of biofilms threatens and exacerbates S. aureus infection by allowing the bacteria to adhere to pathological areas and livestock product surfaces, thus triggering animal health crises and safety issues with livestock products. To solve this problem, in this review, we provide a brief overview of the harm caused by S. aureus and its biofilms on livestock and animal byproducts(meat and dairy products). We also describe the ways in which S. aureus spreads in animals and the threats it poses to the livestock industry. The processes and molecular mechanisms involved in biofilm formation are then explained. Finally, we discuss strategies for the removal and eradication of S. aureus and biofilms in animal husbandry, including the use of antimicrobial peptides, plant extracts, nanoparticles, phages, and antibodies. These strategies to reduce the spread of S. aureus in animal husbandry help maintain livestock health and improve productivity to ensure the ecologically sustainable development of animal husbandry and the safety of livestock products.展开更多
Mycotoxins are toxic secondary metabolites produced by filamentous fungi that are commonly detected as natural contaminants in agricultural commodities worldwide.Mycotoxin exposure can lead to mycotoxicosis in both an...Mycotoxins are toxic secondary metabolites produced by filamentous fungi that are commonly detected as natural contaminants in agricultural commodities worldwide.Mycotoxin exposure can lead to mycotoxicosis in both animals and humans when found in animal feeds and food products,and at lower concentrations can affect animal performance by disrupting nutrient digestion,absorption,metabolism,and animal physiology.Thus,mycotoxin contamination of animal feeds represents a significant issue to the livestock industry and is a health threat to food animals.Since prevention of mycotoxin formation is difficult to undertake to avoid contamination,mitigation strategies are needed.This review explores how the mycotoxins aflatoxins,deoxynivalenol,zearalenone,fumonisins and ochratoxin A impose nutritional and metabolic effects on food animals and summarizes mitigation strategies to reduce the risk of mycotoxicity.展开更多
This paper reviews the fire problem in critical transportation infrastructures such as bridges and tunnels.The magnitude of the fire problem is illustrated,and the recent increase in fire problems in bridges and tunne...This paper reviews the fire problem in critical transportation infrastructures such as bridges and tunnels.The magnitude of the fire problem is illustrated,and the recent increase in fire problems in bridges and tunnels is highlighted.Recent research undertaken to address fire problems in transportation structures is reviewed,as well as critical factors governing the performance of those structures.Furthermore,key strategies recommended for mitigating fire hazards in bridges and tunnels are presented,and their applicability to practical situations is demonstrated through a practical case study.Furthermore,research needs and emerging trends for enhancing the“state-of-the-art”in this area are discussed.展开更多
Todays,most Iraqi cities suffer from extremely hot-dry climate for long periods throughout the year.However,most urban patterns that exist inside these cities are not suitable for this harsh conditions and lead to an ...Todays,most Iraqi cities suffer from extremely hot-dry climate for long periods throughout the year.However,most urban patterns that exist inside these cities are not suitable for this harsh conditions and lead to an increase in the value of the Urban Heat Island(UHI)index.Consequently,this will increase outdoor human thermal discomfort as well as energy consumption and air pollution in cities.This study attempts to evaluate the effect of UHI mitigation strategies on outdoor human thermal comfort in three different common types of urban patterns in the biggest and most populated city in Iraq,Baghdad.Three different mitigation strategies are used here-vegetation,cool materials,and urban geometry-to build 18 different scenarios.Three-dimensional numerical software ENVI-met 4.2 is utilised to analyse and assess the studied parameters.The input data for simulations process are based on two meteorological stations in Baghdad:Iraqi Meteorological Organization&Seismology,and Iraqi Agrometeorological Network.All measurements are taken in a pedestrian walkway.The results of different scenarios are compared based on their effect on human thermal comfort.Outdoor thermal comfort is assessed according to Predicted Mean Vote index,as mentioned in ISO 7730 standard.This study provides a better understanding of the role of UHI mitigation strategies on human thermal comfort in the outdoor spaces of Baghdad’s residential neighbourhoods.This can help generate guidelines of urban design and planning practices for better thermal performance in hot and dry cities.展开更多
Deepwater oilfields will become main sources of the world's oil and gas production.It is characterized with high technology,huge investment,long duration,high risk and high profit.It is a huge system project,inclu...Deepwater oilfields will become main sources of the world's oil and gas production.It is characterized with high technology,huge investment,long duration,high risk and high profit.It is a huge system project,including exploration and appraising,field development plan(FDP)design,implementation,reservoir management and optimization.Actually,limited data,international environment and oil price will cause much uncertainty for FDP design and production management.Any unreasonable decision will cause huge loss.Thus,risk foreseeing and mitigation strategies become more important.This paper takes AKPO and EGINA as examples to analyze the main uncertainties,proposes mitigation strategies,and provides valuable experiences for the other deepwater oilfields development.展开更多
The Science teachers in primary schools are the key group in developing science education, and they play a vital role in realizing the dream of strengthening the country through education. Their professional happiness...The Science teachers in primary schools are the key group in developing science education, and they play a vital role in realizing the dream of strengthening the country through education. Their professional happiness deserves special attention. Whether this group is happy not only affects their own working conditions and quality of life, but also affects the work vitality of other teachers. Improving the professional happiness of science teachers in primary schools has become an important topic in the construction of teachers’ team in the new period. At present, the intensity of primary school science teachers’ own work is high, their non-own work is increasing, their physical and mental health is difficult to guarantee, and their professional happiness is reduced. The main causes of the problems are poor individual psychological quality, poor school management style and improper social cognitive evaluation. In order to solve this problem, we have explored strategies to improve the professional happiness of science teachers in primary schools through reshaping teachers’ work, democratic management of schools and national policy guarantee.展开更多
Investigating the spatio-temporal transmission features and process of novel coronavirus disease 2019(COVID-19)mitigation strategies are of great practical significance to understand the development of COVID-19 and es...Investigating the spatio-temporal transmission features and process of novel coronavirus disease 2019(COVID-19)mitigation strategies are of great practical significance to understand the development of COVID-19 and establish international cooperation for prevention and control.In this paper,the cumulative number of confirmed cases,number of confirmed cases per day and cumulative number of deaths,were used to compare transmission paths,outbreaks timelines,and coping strategies of COVID-19 in China and the US.The results revealed that:first,the COVID-19 outbreaks in both China and the US exhibited a 6-week initiation stage.In China,the COVID-19 erupted in late January.It lasted only a short period of time and was almost completely contained within 6-8 weeks.But the COVID-19 erupted in early March in the US and was still in the peak or post-peak stage.Second,in China,the COVID-19 emerged in Wuhan and spread to other regions of Hubei Province and then nationwide,exhibiting a cross('+')-shaped of spread with Wuhan city as the center.Importantly,the COVID-19 in China had a large concentration and there were no national outbreaks.In contrast,the COVID-19 in the US first spread through New York and the western and eastern coasts but has since emerged throughout the entire country.Third,the lack of emergency response planning in both countries in the early stage(about 6-week)hampered COVID-19 prevention.However,actively high-pressure prevention and control measures were used to basically control COVID-19 in early March in China.And then China has gradually resumed business and production activities.Unfortunately,the US government missed the best opportunity to contain the epidemic.Faced with the choice between economic recovery and coronavirus containment,the US removed the quarantine and restriction measures too early.The COVID-19 is continuing to spread in the country and blossom everywhere,still showing no signs of receding.展开更多
This review aims to highlight the effects of ochratoxin A(OTA)in the feed of meat-producing animals.The accumulation of OTA in feed and its distribution in various farm animals were compared and evaluated.Primarily,th...This review aims to highlight the effects of ochratoxin A(OTA)in the feed of meat-producing animals.The accumulation of OTA in feed and its distribution in various farm animals were compared and evaluated.Primarily,the oral administration of OTA-contaminated feed and the predisposition in an animal's vital organ were critically examined in this work.The collated reports show that OTA directly associated with endemic nephropathy and its high concentration leads to degeneration of liver cells,and necrosis of intestinal and lymphoid tissues.At present,limited reports are available in the recent liter-ature on the problems and consequences of OTA in feed.Therefore,this review focused on the OTA carryover from feed to farm animals and the interaction of its secondary metabolites on their biochemical parameters.Hence,this report provides greater insights into animal health related to OTA residues in meat and meat products.This article also explores mitigation strategies that can be used to prevent the carryover effects of OTA in livestock feeds and the effects in the food chain.展开更多
Long-runout rockslides at high altitude could cause disaster chain in river basins and destroy towns and major infrasturctures.This paper firstly explores the initiation mechanism of high-altitude and long-runout rock...Long-runout rockslides at high altitude could cause disaster chain in river basins and destroy towns and major infrasturctures.This paper firstly explores the initiation mechanism of high-altitude and long-runout rockslides.Two types of sliding-prone geostructure models,i.e.the fault control type in orogenic belt and the fold control type in platform area,are proposed.Then,large-scale experimental apparatus and associated numerical simulations are conducted to understanding the chain-style dynamics of rockslide-debris avalanche-debris flow.The results reveal the fragmentation effects,the rheological behaviors and the boundary layer effect of long-runout avalanche-debris flow.The dynamic character-istics of quasi-static-transition-inertia state and solid-liquid coupling in rapid movement of rockslide-debris avalanche-debris flow are investigated.Finally,the risk mitigation strategy of the non-structure and structure for resilient energy dissipation are illustrated for initiation,transition and deposition zones.The structural prevention and mitigation methods have been successfully applied to the high-altitude and long-runout rockslides in Zhouqu and Maoxian of the Wenchuan earthquake zone,as well as the other major geohazards in Qinghai-Tibet Plateau and its adjacent areas.展开更多
Desertification and dust storms and their impact on the Chinese economy and the environment were examined. A context was established using the best information available on the trends of desertification and dust storm...Desertification and dust storms and their impact on the Chinese economy and the environment were examined. A context was established using the best information available on the trends of desertification and dust storms in China. Building on the context, the second section the root causes of desertification and dust storms were examined. Several myths were sought to be identified about some core issues surrounding desertification and dust storms. China’s National Action Plan to combat desertification was reviewed and the effectiveness of existing strategies and programs for mitigating the adverse effects of desertification and dust storms were discussed. The future research needed was pointed out.展开更多
Drilling is one of the most challenging and expensive processes in hydrocarbon extraction and geothermal well development.Dysfunctions faced during drilling can increase the non-productive time(NPT)greatly,resulting i...Drilling is one of the most challenging and expensive processes in hydrocarbon extraction and geothermal well development.Dysfunctions faced during drilling can increase the non-productive time(NPT)greatly,resulting in inflating the drilling cost and also pose a safety concern.One of the main problems faced during drilling that limits the life of drilling equipment and tools and decreases the overall productivity of the system is drilling vibrations.These vibrations can be categorized into three modes:axial,lateral,and torsional.Stick-slip vibrations are a type of torsional vibration in which the bottom hole assembly(BHA)periodically stops to rotate followed by a spike in the bottom hole RPM.This paper provides a comprehensive review of techniques used to control and mitigate torsional vibration with an emphasis on stick-slip.A brief introduction to drillstring and friction modeling is presented followed by a concise summary of passive control techniques to control stick-slip.Then the focus is shifted to an up-to-date review of active control and machine learning for stick-slip control and mitigation.The paper ultimately highlights the importance of adapting novel control and mitigation concepts to improve stick slip detection and improve the overall drilling process.A unique solution is insufficient to control a complex process such as drilling,but integration of various techniques has been found promising.展开更多
Increasing urbanization in the cities of northern Mexico reflects a general trend to increased temperatures, so it is likely that heat waves amplify the frequency and intensity in urban centers, mainly located in arid...Increasing urbanization in the cities of northern Mexico reflects a general trend to increased temperatures, so it is likely that heat waves amplify the frequency and intensity in urban centers, mainly located in arid and semiarid as Mexicali city with extremely arid climate, very hot in summer and cold and rainy in winter. Mexicali, Baja California, Mexico is located at N32°38' and W115°20'. The urban area is expanded over 14,890 hectares, with a population rise the 689,775. In the last four decades has experienced an accelerated industrial growth and mismatched land uses, for example: most of the industrial parks were established before the 1980 in what was the outskirts of the city, but nowadays practically are inside of the urban area contributing to the increase the urban temperature. The heat islands profile shows that are intensified in industrial areas as well as trade and services. The preliminary scenarios of climate change for Mexicali indicate that for the decade of 2080 the temperature will increase between 4.2℃ and 4.4℃. This paper addresses in a simulation context, an industrial and commercial city sector and their ability to implement urban heat island mitigation strategies. The simulation of this process requires several spatial analysis tools and specific knowledge about the processes that increase urban temperatures. In this work, only land use, land cover and buildings are considered. The proposed method takes into account the actual spatial organization to analyze trends for the proposed growth areas.展开更多
To feed an increasing population, large amounts of chemical nitrogen fertilizer have been used to produce much of our food, feed and fiber thereby increasing nitrogen levels in soils, natural waters, crop residues, li...To feed an increasing population, large amounts of chemical nitrogen fertilizer have been used to produce much of our food, feed and fiber thereby increasing nitrogen levels in soils, natural waters, crop residues, livestock wastes,and municipal and agricultural wastes, with national and international concern about its potential adverse effects on environmental quality and public health. To understand these phenomena and problems, first the nitrogen cycle and the environment are described. Then recent trends for nitrogen cycling through the food and feed system, N2O emissions from fertilized upland and paddy soils, and NO-3 pollution in ground water in Japan are reported. Finally, mitigation strategies in Japan for reducing N2O emission and NO-3 pollution are proposed, including nitrification inhibitors, controlled release fertilizers, utilization of plant species that could suppress nitrification, utilizing the toposequence, government policy, and appropriate agricultural practices. Of all the technologies presented, use of nitrification inhibitors and controlled release fertilizers are deemed the most important with further development of these aspects of technologies being expected. These practices, if employed worldwide, could help reduce the load, or environmental deterioration, on the Earth's biosphere.展开更多
文摘Cloud computing plays a significant role in modern information technology, providing organizations with numerous benefits, including flexibility, scalability, and cost-efficiency. However, it has become essential for organizations to ensure the security of their applications, data, and cloud-based networks to use cloud services effectively. This systematic literature review aims to determine the latest information regarding cloud computing security, with a specific emphasis on threats and mitigation strategies. Additionally, it highlights some common threats related to cloud computing security, such as distributed denial-of-service (DDoS) attacks, account hijacking, malware attacks, and data breaches. This research also explores some mitigation strategies, including security awareness training, vulnerability management, security information and event management (SIEM), identity and access management (IAM), and encryption techniques. It discusses emerging trends in cloud security, such as integrating artificial intelligence (AI) and machine learning (ML), serverless computing, and containerization, as well as the effectiveness of the shared responsibility model and its related challenges. The importance of user awareness and the impact of emerging technologies on cloud security have also been discussed in detail to mitigate security risks. A literature review of previous research and scholarly articles has also been conducted to provide insights regarding cloud computing security. It shows the need for continuous research and innovation to address emerging threats and maintain a security-conscious culture in the company.
文摘Objective:To investigate the safety hazards in nursing and explore mitigation strategies for elderly patients in the endocrinology department.Methods:A total of 240 bedridden elderly patients from February 2021 to January 2023 were recruited and divided into two groups using the random number table method.The control group(n=120)received conventional nursing care,and the observation group(n=120)received personalized nursing care.Patients’quality of life,the incidence rate of pressure sores,and patient satisfaction with nursing care were observed and analyzed.Results:The incidence of pressure ulcers in the observation group was significantly lower at 17.50%compared to 30.00%in the control group(P<0.05).Quality of life in the observation group was significantly higher than that in the control group(P<0.05).The satisfaction rate in the observation group was significantly higher at 93.33%compared to 84.17%in the control group(P<0.05).Conclusion:These findings emphasize that only through the implementation of scientific and rational nursing measures can effectively reduce nursing risks,enhance therapeutic outcomes,and improve the quality of life for elderly patients.
基金supported by the National Key R&D Program of China(2017YFB0310100)the National Basic Research Program of China(2015CB655105)the National Outstanding Youth Science Foundation Program(51225801).
文摘The complex compositions and large shrinkage of concrete,as well as the strong constraints of the structures,often lead to prominent shrinkage cracking problems in modem concrete structures.This paper first introduces a multi-field(hydro-thermo-hygro-constraint)coupling model with the hydration degree of cementitious materials as the basic state parameter to estimate the shrinkage cracking risk of hardening concrete under coupling effects.Second,three new key technologies are illustrated:temperature rise inhibition,full-stage shrinkage compensation,and shrinkage reduction technologies.These technologies can efficiently reduce the thermal,autogenous,and drying shrinkages of concrete.There after,a design process based on the theoretical model and key technologies is proposed to control thecracking risk index below the threshold value.Finally,two engineering application examples are provided that demonstrate that concrete shrinkage cracking can be significantly mitigated by adopting the proposed methods and technologies.
文摘A low-frequency debris flow took place in the north coastal range of Venezuela on Dec. 16, 1999, and scientists all over the world paid attention to this catastrophe. Four characteristics of low-frequency debris hazard are discussed: long return period and extreme catastrophe, special rare triggering factors, difficulty in distinguishing and a series of small hazards subsequent to the catastrophe. Different measures, such as preventing, forecast - warning, engineering, can be used for mitigating and controlling the catastrophe. In engineering practice, it is a key that large silt-trap dams are used to control rare large debris flow. A kind of low dam with cheap cost can be used to replace high dam in developing countries. A planning for controlling debris flow hazard in Cerro Grande stream of Venezuela is presented at the end of this paper.
基金supported by National Basic Research Program of China(973 Program,Grant No.2012CB215500)National Hi-tech Research and Development Program of China(863 Program,Grant Nos.2012AA1106012,2012AA053402)+1 种基金National Natural Science Foundation of China(Grant No.20976095)the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20090002110074)
文摘The accelerated degradation in the front ceils of a polymer electrolyte membrane fuel cell(PEMFC) stack seriously reduces the reliability and durability of the whole stack. Most researches only focus on the size and configuration of the gas intake manifold, which may lead to the maldistribution of flow and pressure. In order to find out the mechanisms of the accelerated degradation in the front cells, an extensive program of experimental and simulation work is initiated and the results are reported. It is found that after long-term lifetime tests the accelerated degradation in the front cells occurs in all three fuel cell stacks with different flow-fields under the U-type feed configuration. Compared with the rear cells of the stack, the voltage of the front cells is much lower at the same current densities and the membrane electrode assembly(MEA) has smaller active area, more catalyst particle agglomeration and higher ohmic impedance. For further investigation, a series of three dimensional isothermal numerical models are built to investigate the degradation mechanisms based on the experimental data. The simulation results reveal that the dry working condition of the membrane and the effect of high-speed gas scouting the MEA are the main causes of the accelerated degradation in the front cells of a PEM fuel cell stack under the U-type feed configuration. Several mitigation strategies that would mitigate these phenomena are presented: removing cells that have failed and replacing them with those of the same aging condition as the average of the stack; choosing a Z-type feed pattern instead of a U-type one; putting several air flow-field plates without MEA in the front of the stack; or exchanging the gas inlet and outlet alternately at a certain interval. This paper specifies the causes of the accelerated degradation in the front cells and provides the mitigation strategies.
基金funding by the National Natural Science Foundation of China(Grant No.42007416)the Hong Kong Polytechnic University Strategic Importance Fund(ZE2T)and Project of Research Institute of Land and Space(CD78).
文摘This study proposes an approach that considers mitigation strategies in predicting landslide susceptibility through machine learning(ML)and geographic information system(GIS)techniques.ML models,such as random forest(RF),logistic regression(LR),and support vector classification(SVC)are incorporated into GIS to predict landslide susceptibilities in Hong Kong.To consider the effect of mitigation strategies on landslide susceptibility,non-landslide samples were produced in the upgraded area and added to randomly created samples to serve as ML models in training datasets.Two scenarios were created to compare and demonstrate the efficiency of the proposed approach;Scenario I does not considering landslide control while Scenario II considers mitigation strategies for landslide control.The largest landslide susceptibilities are 0.967(from RF),followed by 0.936(from LR)and 0.902(from SVC)in Scenario II;in Scenario I,they are 0.986(from RF),0.955(from LR)and 0.947(from SVC).This proves that the ML models considering mitigation strategies can decrease the current landslide susceptibilities.The comparison between the different ML models shows that RF performed better than LR and SVC,and provides the best prediction of the spatial distribution of landslide susceptibilities.
基金Supported by the National Natural Science Foundation of China (42021004 and 42175032)。
文摘The combined effects of global warming and the urban heat islands exacerbate the risk of urban heat stress. It is crucial to implement effective cooling measures in urban areas to improve the comfort of the thermal environment. In this study, the Weather Research and Forecasting Model(WRF), coupled with a single-layer Urban Canopy Model(UCM), was used to study the impact of heat mitigation strategies. In addition, a 5-km resolution land-cover dataset for China(ChinaLC), which is based on satellite remote sensing data, was adjusted and used, and 18 groups of numerical experiments were designed, to increase the albedo and vegetation fraction of roof/ground parameters. The experiments were conducted for four heatwave events that occurred in the summer of 2013 in the Yangtze River Delta urban agglomeration of China. The simulated results demonstrated that, for the single roof/ground schemes, the mitigation effects were directly proportional to the albedo and greening. Among all the experimental schemes, the superposed schemes presented better cooling effects. For the ground greening scheme, with similar net radiation flux and latent heat flux, its storage heat was lower than that of the roof greening scheme, resulting in more energy flux into the atmosphere, and its daytime cooling effect was not as good as that of the roof greening scheme. In terms of human thermal comfort(HTC), the improvement achieved by the ground greening scheme was better than any other single roof/ground schemes, because the increase in the relative humidity was small. The comprehensive evaluation of the mitigation effects of different schemes on the thermal environment presented in this paper provides a theoretical basis for improving the urban environment through rational urban planning and construction.
基金supported by the National Natural Science Foundation of China (31930106 and U22A20514, U23A20232)the National Key R&D Program of China (2022YFD1300404)+2 种基金the 2115 Talent Development Program of China Agricultural University (1041-00109019)the Pinduoduo-China Agricultural University Research Fund (PC2023A01001)the Special Fund for Henan Agriculture Research System (HARS-2213-Z1)。
文摘Staphylococcus aureus(S. aureus) is a common pathogenic bacterium in animal husbandry that can cause diseases such as mastitis, skin infections, arthritis, and other ailments. The formation of biofilms threatens and exacerbates S. aureus infection by allowing the bacteria to adhere to pathological areas and livestock product surfaces, thus triggering animal health crises and safety issues with livestock products. To solve this problem, in this review, we provide a brief overview of the harm caused by S. aureus and its biofilms on livestock and animal byproducts(meat and dairy products). We also describe the ways in which S. aureus spreads in animals and the threats it poses to the livestock industry. The processes and molecular mechanisms involved in biofilm formation are then explained. Finally, we discuss strategies for the removal and eradication of S. aureus and biofilms in animal husbandry, including the use of antimicrobial peptides, plant extracts, nanoparticles, phages, and antibodies. These strategies to reduce the spread of S. aureus in animal husbandry help maintain livestock health and improve productivity to ensure the ecologically sustainable development of animal husbandry and the safety of livestock products.
基金funded by Natural Sciences and Engineering Research Council of Canada and Alltech Inc,KY,US[532378-18].
文摘Mycotoxins are toxic secondary metabolites produced by filamentous fungi that are commonly detected as natural contaminants in agricultural commodities worldwide.Mycotoxin exposure can lead to mycotoxicosis in both animals and humans when found in animal feeds and food products,and at lower concentrations can affect animal performance by disrupting nutrient digestion,absorption,metabolism,and animal physiology.Thus,mycotoxin contamination of animal feeds represents a significant issue to the livestock industry and is a health threat to food animals.Since prevention of mycotoxin formation is difficult to undertake to avoid contamination,mitigation strategies are needed.This review explores how the mycotoxins aflatoxins,deoxynivalenol,zearalenone,fumonisins and ochratoxin A impose nutritional and metabolic effects on food animals and summarizes mitigation strategies to reduce the risk of mycotoxicity.
基金This study was supported by the National Science Foundation(No.CMMI-1068621).
文摘This paper reviews the fire problem in critical transportation infrastructures such as bridges and tunnels.The magnitude of the fire problem is illustrated,and the recent increase in fire problems in bridges and tunnels is highlighted.Recent research undertaken to address fire problems in transportation structures is reviewed,as well as critical factors governing the performance of those structures.Furthermore,key strategies recommended for mitigating fire hazards in bridges and tunnels are presented,and their applicability to practical situations is demonstrated through a practical case study.Furthermore,research needs and emerging trends for enhancing the“state-of-the-art”in this area are discussed.
文摘Todays,most Iraqi cities suffer from extremely hot-dry climate for long periods throughout the year.However,most urban patterns that exist inside these cities are not suitable for this harsh conditions and lead to an increase in the value of the Urban Heat Island(UHI)index.Consequently,this will increase outdoor human thermal discomfort as well as energy consumption and air pollution in cities.This study attempts to evaluate the effect of UHI mitigation strategies on outdoor human thermal comfort in three different common types of urban patterns in the biggest and most populated city in Iraq,Baghdad.Three different mitigation strategies are used here-vegetation,cool materials,and urban geometry-to build 18 different scenarios.Three-dimensional numerical software ENVI-met 4.2 is utilised to analyse and assess the studied parameters.The input data for simulations process are based on two meteorological stations in Baghdad:Iraqi Meteorological Organization&Seismology,and Iraqi Agrometeorological Network.All measurements are taken in a pedestrian walkway.The results of different scenarios are compared based on their effect on human thermal comfort.Outdoor thermal comfort is assessed according to Predicted Mean Vote index,as mentioned in ISO 7730 standard.This study provides a better understanding of the role of UHI mitigation strategies on human thermal comfort in the outdoor spaces of Baghdad’s residential neighbourhoods.This can help generate guidelines of urban design and planning practices for better thermal performance in hot and dry cities.
文摘Deepwater oilfields will become main sources of the world's oil and gas production.It is characterized with high technology,huge investment,long duration,high risk and high profit.It is a huge system project,including exploration and appraising,field development plan(FDP)design,implementation,reservoir management and optimization.Actually,limited data,international environment and oil price will cause much uncertainty for FDP design and production management.Any unreasonable decision will cause huge loss.Thus,risk foreseeing and mitigation strategies become more important.This paper takes AKPO and EGINA as examples to analyze the main uncertainties,proposes mitigation strategies,and provides valuable experiences for the other deepwater oilfields development.
文摘The Science teachers in primary schools are the key group in developing science education, and they play a vital role in realizing the dream of strengthening the country through education. Their professional happiness deserves special attention. Whether this group is happy not only affects their own working conditions and quality of life, but also affects the work vitality of other teachers. Improving the professional happiness of science teachers in primary schools has become an important topic in the construction of teachers’ team in the new period. At present, the intensity of primary school science teachers’ own work is high, their non-own work is increasing, their physical and mental health is difficult to guarantee, and their professional happiness is reduced. The main causes of the problems are poor individual psychological quality, poor school management style and improper social cognitive evaluation. In order to solve this problem, we have explored strategies to improve the professional happiness of science teachers in primary schools through reshaping teachers’ work, democratic management of schools and national policy guarantee.
基金Strategic Priority Research Program of Chinese Academy of Sciences,No.XDA20010203Second Tibetan Plateau Scientific Expedition and Research Program(STEP),No.2019QZKK1006。
文摘Investigating the spatio-temporal transmission features and process of novel coronavirus disease 2019(COVID-19)mitigation strategies are of great practical significance to understand the development of COVID-19 and establish international cooperation for prevention and control.In this paper,the cumulative number of confirmed cases,number of confirmed cases per day and cumulative number of deaths,were used to compare transmission paths,outbreaks timelines,and coping strategies of COVID-19 in China and the US.The results revealed that:first,the COVID-19 outbreaks in both China and the US exhibited a 6-week initiation stage.In China,the COVID-19 erupted in late January.It lasted only a short period of time and was almost completely contained within 6-8 weeks.But the COVID-19 erupted in early March in the US and was still in the peak or post-peak stage.Second,in China,the COVID-19 emerged in Wuhan and spread to other regions of Hubei Province and then nationwide,exhibiting a cross('+')-shaped of spread with Wuhan city as the center.Importantly,the COVID-19 in China had a large concentration and there were no national outbreaks.In contrast,the COVID-19 in the US first spread through New York and the western and eastern coasts but has since emerged throughout the entire country.Third,the lack of emergency response planning in both countries in the early stage(about 6-week)hampered COVID-19 prevention.However,actively high-pressure prevention and control measures were used to basically control COVID-19 in early March in China.And then China has gradually resumed business and production activities.Unfortunately,the US government missed the best opportunity to contain the epidemic.Faced with the choice between economic recovery and coronavirus containment,the US removed the quarantine and restriction measures too early.The COVID-19 is continuing to spread in the country and blossom everywhere,still showing no signs of receding.
基金National Research Foundation(NRF)of South Korea(Grant No:2018R1C1B5086232)funded by Korean Government(MEST).
文摘This review aims to highlight the effects of ochratoxin A(OTA)in the feed of meat-producing animals.The accumulation of OTA in feed and its distribution in various farm animals were compared and evaluated.Primarily,the oral administration of OTA-contaminated feed and the predisposition in an animal's vital organ were critically examined in this work.The collated reports show that OTA directly associated with endemic nephropathy and its high concentration leads to degeneration of liver cells,and necrosis of intestinal and lymphoid tissues.At present,limited reports are available in the recent liter-ature on the problems and consequences of OTA in feed.Therefore,this review focused on the OTA carryover from feed to farm animals and the interaction of its secondary metabolites on their biochemical parameters.Hence,this report provides greater insights into animal health related to OTA residues in meat and meat products.This article also explores mitigation strategies that can be used to prevent the carryover effects of OTA in livestock feeds and the effects in the food chain.
基金This work was financially supported by National Natural Science Foundation of China(Grant Nos.U2244226,U2244227 and 42177172).
文摘Long-runout rockslides at high altitude could cause disaster chain in river basins and destroy towns and major infrasturctures.This paper firstly explores the initiation mechanism of high-altitude and long-runout rockslides.Two types of sliding-prone geostructure models,i.e.the fault control type in orogenic belt and the fold control type in platform area,are proposed.Then,large-scale experimental apparatus and associated numerical simulations are conducted to understanding the chain-style dynamics of rockslide-debris avalanche-debris flow.The results reveal the fragmentation effects,the rheological behaviors and the boundary layer effect of long-runout avalanche-debris flow.The dynamic character-istics of quasi-static-transition-inertia state and solid-liquid coupling in rapid movement of rockslide-debris avalanche-debris flow are investigated.Finally,the risk mitigation strategy of the non-structure and structure for resilient energy dissipation are illustrated for initiation,transition and deposition zones.The structural prevention and mitigation methods have been successfully applied to the high-altitude and long-runout rockslides in Zhouqu and Maoxian of the Wenchuan earthquake zone,as well as the other major geohazards in Qinghai-Tibet Plateau and its adjacent areas.
文摘Desertification and dust storms and their impact on the Chinese economy and the environment were examined. A context was established using the best information available on the trends of desertification and dust storms in China. Building on the context, the second section the root causes of desertification and dust storms were examined. Several myths were sought to be identified about some core issues surrounding desertification and dust storms. China’s National Action Plan to combat desertification was reviewed and the effectiveness of existing strategies and programs for mitigating the adverse effects of desertification and dust storms were discussed. The future research needed was pointed out.
文摘Drilling is one of the most challenging and expensive processes in hydrocarbon extraction and geothermal well development.Dysfunctions faced during drilling can increase the non-productive time(NPT)greatly,resulting in inflating the drilling cost and also pose a safety concern.One of the main problems faced during drilling that limits the life of drilling equipment and tools and decreases the overall productivity of the system is drilling vibrations.These vibrations can be categorized into three modes:axial,lateral,and torsional.Stick-slip vibrations are a type of torsional vibration in which the bottom hole assembly(BHA)periodically stops to rotate followed by a spike in the bottom hole RPM.This paper provides a comprehensive review of techniques used to control and mitigate torsional vibration with an emphasis on stick-slip.A brief introduction to drillstring and friction modeling is presented followed by a concise summary of passive control techniques to control stick-slip.Then the focus is shifted to an up-to-date review of active control and machine learning for stick-slip control and mitigation.The paper ultimately highlights the importance of adapting novel control and mitigation concepts to improve stick slip detection and improve the overall drilling process.A unique solution is insufficient to control a complex process such as drilling,but integration of various techniques has been found promising.
文摘Increasing urbanization in the cities of northern Mexico reflects a general trend to increased temperatures, so it is likely that heat waves amplify the frequency and intensity in urban centers, mainly located in arid and semiarid as Mexicali city with extremely arid climate, very hot in summer and cold and rainy in winter. Mexicali, Baja California, Mexico is located at N32°38' and W115°20'. The urban area is expanded over 14,890 hectares, with a population rise the 689,775. In the last four decades has experienced an accelerated industrial growth and mismatched land uses, for example: most of the industrial parks were established before the 1980 in what was the outskirts of the city, but nowadays practically are inside of the urban area contributing to the increase the urban temperature. The heat islands profile shows that are intensified in industrial areas as well as trade and services. The preliminary scenarios of climate change for Mexicali indicate that for the decade of 2080 the temperature will increase between 4.2℃ and 4.4℃. This paper addresses in a simulation context, an industrial and commercial city sector and their ability to implement urban heat island mitigation strategies. The simulation of this process requires several spatial analysis tools and specific knowledge about the processes that increase urban temperatures. In this work, only land use, land cover and buildings are considered. The proposed method takes into account the actual spatial organization to analyze trends for the proposed growth areas.
基金Project supported by the Canadian International Development Agency, Canada and the Chinese Academy of Scicences, China (No. KZCX2-413)
文摘To feed an increasing population, large amounts of chemical nitrogen fertilizer have been used to produce much of our food, feed and fiber thereby increasing nitrogen levels in soils, natural waters, crop residues, livestock wastes,and municipal and agricultural wastes, with national and international concern about its potential adverse effects on environmental quality and public health. To understand these phenomena and problems, first the nitrogen cycle and the environment are described. Then recent trends for nitrogen cycling through the food and feed system, N2O emissions from fertilized upland and paddy soils, and NO-3 pollution in ground water in Japan are reported. Finally, mitigation strategies in Japan for reducing N2O emission and NO-3 pollution are proposed, including nitrification inhibitors, controlled release fertilizers, utilization of plant species that could suppress nitrification, utilizing the toposequence, government policy, and appropriate agricultural practices. Of all the technologies presented, use of nitrification inhibitors and controlled release fertilizers are deemed the most important with further development of these aspects of technologies being expected. These practices, if employed worldwide, could help reduce the load, or environmental deterioration, on the Earth's biosphere.