Deep foundation pit excavation is a basic and key step involved in modern building construction.In order to ensure the construction quality and safety of deep foundation pits,this paper takes a project as an example t...Deep foundation pit excavation is a basic and key step involved in modern building construction.In order to ensure the construction quality and safety of deep foundation pits,this paper takes a project as an example to analyze deep foundation pit excavation technology,including the nature of this construction project,the main technical measures in the construction of deep foundation pit,and the analysis of the safety risk prevention and control measures.The purpose of this analysis is to provide scientific reference for the construction quality and safety of deep foundation pits.展开更多
The purpose of this study is to reduce the uncertainty in the calculation process on hesitant fuzzy sets(HFSs).The innovation of this study is to unify the cardinal numbers of hesitant fuzzy elements(HFEs)in a special...The purpose of this study is to reduce the uncertainty in the calculation process on hesitant fuzzy sets(HFSs).The innovation of this study is to unify the cardinal numbers of hesitant fuzzy elements(HFEs)in a special way.Firstly,a probability density function is assigned for any given HFE.Thereafter,equal-probability transformation is introduced to transform HFEs with different cardinal numbers on the condition into the same probability density function.The characteristic of this transformation is that the higher the consistency of the membership degrees in HFEs,the higher the credibility of the mentioned membership degrees is,then,the bigger the probability density values for them are.According to this transformation technique,a set of novel distance measures on HFSs is provided.Finally,an illustrative example of intersection traffic control is introduced to show the usefulness of the given distance measures.The example also shows that this study is a good complement to operation theories on HFSs.展开更多
Introduction: The management of hypertension is mostly based on pharmacotherapy and hygienic and dietary measures (HDMs) for which little data is available in Cameroon. The concern to improve the quality of life of hy...Introduction: The management of hypertension is mostly based on pharmacotherapy and hygienic and dietary measures (HDMs) for which little data is available in Cameroon. The concern to improve the quality of life of hypertensive patients led us to study the knowledge, compliance and effect of HDMs among Cameroonian hypertensive patients. Methods: This was a cross-sectional study carried out at the Douala General Hospital;the census of patients was carried out from 05 March to 10 May 2018. The data evaluated were knowledge and compliance with HDMs with an inference of their effect on blood pressure control. Results: We recruited 330 participants at mean age of 60 ± 11 years, 37.9% men;57.3% with blood pressure (BP) controlled. Out of 330 subjects, 308 (93.3%) who had been educated about dietary health measures for hypertension were assessed on knowledge, compliance and effect of these measures against 22 (6.7%) who had never heard about them. Around 85.7% of participants had good knowledge of HDMs and 78.9% had good compliance with them. There was no statistically significant influence of knowledge and compliance with HDMs on blood pressure control. Conclusion: The level of knowledge and adherence to HDMs of hypertensive patients at the Douala General Hospital was appreciable. It is however appropriate for physicians to intensify patient education on HDMs and BP control.展开更多
Based on practical work experience,this paper analyzed the occurrence characteristics and control measures of Spodoptera frugiperda in maize.The measures including forecasting and early warning,regional prevention and...Based on practical work experience,this paper analyzed the occurrence characteristics and control measures of Spodoptera frugiperda in maize.The measures including forecasting and early warning,regional prevention and control,agricultural prevention and control,physical prevention and control,chemical prevention and control,and biological prevention and control can effectively control the damage of S.frugiperda and guarantee the safety of food production.The results will provide some reference for the prevention and control of S.frugiperda.展开更多
The Jinping I hydropower station is a huge water conservancy project consisting of the highest concrete arch dam to date in the world and a highly complex and large underground powerhouse cavern. It is located on the ...The Jinping I hydropower station is a huge water conservancy project consisting of the highest concrete arch dam to date in the world and a highly complex and large underground powerhouse cavern. It is located on the right bank with extremely high in-situ stress and a few discontinuities observed in surrounding rock masses. The problems of rock mass deformation and failure result in considerable challenges related to project design and construction and have raised a wide range of concerns in the fields of rock mechanics and engineering. During the excavation of underground caverns, high in-situ stress and relatively low rock mass strength in combination with large excavation dimensions lead to large deformation of the surrounding rock mass and support. Existing experiences in excavation and support cannot deal with the large deformation of rock mass effectively, and further studies are needed. In this paper, the geological conditions, layout of caverns, and design of excavation and support are first introduced, and then detailed analyses of deformation and failure characteristics of rocks are presented. Based on this, the mechanisms of deformation and failure are discussed, and the support adjustments for controlling rock large deformation and subsequent excavation procedures are proposed. Finally, the effectiveness of support and excavation adjustments to maintain the stability of the rock mass is verified. The measures for controlling the large deformation of surrounding rocks enrich the practical experiences related to the design and construction of large underground openings, and the construction of caverns in the Jinping I hydropower station provides a good case study of large-scale excavation in highly stressed ground with complex geological structures, as well as a reference case for research on rock mechanics.展开更多
In-situ pressure-preserved coring(IPP-Coring)is considered to be the most reliable and efficient method for the identification of the scale of oil and gas resources.During IPP-Coring,because the rotation behavior of t...In-situ pressure-preserved coring(IPP-Coring)is considered to be the most reliable and efficient method for the identification of the scale of oil and gas resources.During IPP-Coring,because the rotation behavior of the pressure controller valve cover in different medium environments is unclear,interference between the valve cover and inner pipe may occur and negatively affect the IPP-Coring success rate.To address this issue,we conducted a series of indoor experiments employing a high-speed camera to gain greater insights into the valve cover rotation behavior in different medium environments,e.g.,air,water,and simulated drilling fluids.The results indicated that the variation in the valve cover rotation angle in the air and fluid environments can be described by a one-phase exponential decay function with a constant time parameter and by biphasic dose response function,respectively.The rotation behavior in the fluid environments exhibited distinct elastic and gravitational acceleration zones.In the fluid environments,the density clearly impacted the valve cover closing time and rotation behavior,whereas the effect of viscosity was very slight.This can be attributed to the negligible influence of the fluid viscosity on the drag coefficient found in this study;meanwhile,the density can increase the buoyancy and the time period during which the valve cover experienced a high drag coefficient.Considering these results,control schemes for the valve cover rotation behavior during IPP-Coring were proposed for different layers and geological conditions in which the different drilling fluids should be used,e.g.,the use of a high-density valve cover in high-pore pressure layers.展开更多
Desertification is one of the most serious environmental problems in the world,especially in the arid desert regions.Combating desertification,therefore,is an urgent task on a regional or even global scale.The Taklima...Desertification is one of the most serious environmental problems in the world,especially in the arid desert regions.Combating desertification,therefore,is an urgent task on a regional or even global scale.The Taklimakan Desert in China is the second largest mobile desert in the world and has been called the''Dead Sea''due to few organisms can exist in such a harsh environment.The Taklimakan Desert Highway,the longest desert highway(a total length of 446 km)across the mobile desert in the world,was built in the 1990s within the Taklimakan Desert.It has an important strategic significance regarding oil and gas resources exploration and plays a vital role in the socio-economic development of southern Xinjiang,China.However,wind-blow sand seriously damages the smoothness of the desert highway and,in this case,mechanical sand control system(including sand barrier fences and straw checkerboards)was used early in the life of the desert highway to protect the road.Unfortunately,more than 70%of the sand barrier fences and straw checkerboards have lost their functions,and the desert highway has often been buried and frequently blocked since 1999.To solve this problem,a long artificial shelterbelt with the length of 437 km was built along the desert highway since 2000.However,some potential problems still exist for the sustainable development of the desert highway,such as water shortage,strong sandstorms,extreme environmental characteristics and large maintenance costs.The study aims to provide an overview of the damages caused by wind-blown sand and the effects of sand control measures along the Taklimakan Desert Highway.Ultimately,we provide some suggestions for the biological sand control system to ensure the sustainable development of the Taklimakan Desert Highway,such as screening drought-resistant species to reduce the irrigation requirement and ensure the sound development of groundwater,screening halophytes to restore vegetation in the case of soil salinization,and planting cash crops,such as Cistanche,Wolfberry,Apocynum and other cash crops to decrease the high cost of maintenance on highways and shelterbelts.展开更多
In-situ layerwise imaging measurement of laser powder bed fusion(LPBF)provides a wealth of forming and defect data which enables monitoring of components quality and powder bed homogeneity.Using high-resolution camera...In-situ layerwise imaging measurement of laser powder bed fusion(LPBF)provides a wealth of forming and defect data which enables monitoring of components quality and powder bed homogeneity.Using high-resolution camera layerwise imaging and image processing algorithms to monitor fusion area and powder bed geometric defects has been studied by many researchers,which successfully monitored the contours of components and evaluated their accuracy.However,research for the methods of in-situ 3D contour measurement or component edge warping identification is rare.In this study,a 3D contour mea-surement method combining gray intensity and phase difference is proposed,and its accuracy is verified by designed experiments.The results show that the high-precision of the 3D contours can be achieved by the constructed energy minimization function.This method can detect the deviations of common ge-ometric features as well as warpage at LPBF component edges,and provides fundamental data for in-situ quality monitoring tools.展开更多
In-situ measurement of internal solitary waves(ISWs)is complicated in the ocean due to their randomness.At present,the ISWs are mainly detected by the chain structure of conductivity-temperature-depth systems(CTDs)or ...In-situ measurement of internal solitary waves(ISWs)is complicated in the ocean due to their randomness.At present,the ISWs are mainly detected by the chain structure of conductivity-temperature-depth systems(CTDs)or temperature sensors.The high cost limits the spatial resolution,which ultimately affects the measuring accuracy of the ISW amplitude.In this paper,we developed an experimental measurement system for detecting ISWs based on the stimulated Raman scattering in distributed optical fibers.This system has the advantages of high precision,low cost,and easy operation.The experimental results show that the system is consistent with CTDs in the measurement of vertical ocean temperature variation.The spatial resolution of the system can reach 1.0 m and the measuring accuracy of temperature is 0.2℃.We successfully detected 3 ISWs by the system in the South China Sea and two optical remote sensing images collected on May 18,2021,the same day of two detected ISWs,verify the occurrence of the measured ISWs.We used the image pairs method to calculate the phase velocity of ISW and the result is 1.71 ms^(-1).By extracting the distances between wave packets,it can be found that the semi-diurnal tide generates the detected ISWs.The impact of the tidal current velocity on the ISW in amplitude is undeniable.Undoubtedly,the system has a great application prospect for detecting ISWs and other dynamic phenomena in the ocean.展开更多
Objective Despite the remarkable progress in efforts to control disease spread,the nationwide elimination of hepatitis B in China is still hindered by the persistently high rate of hepatitis B virus(HBV)infection in W...Objective Despite the remarkable progress in efforts to control disease spread,the nationwide elimination of hepatitis B in China is still hindered by the persistently high rate of hepatitis B virus(HBV)infection in Western China.This study aimed to evaluate the strategy of hepatitis B prevention and control in Western China and identify potential areas and strategies for improvement.Methods Susceptible population vaccination,health education,professional training of doctors,and other prevention and control measures have been implemented in Wuwei city since 2010.Data were obtained from three representative cross-sectional serosurveys conducted in 2010,2013,and 2015.The serum samples were subjected to enzyme-linked immunosorbent assays to detect the following seromarkers:HBV surface antigen(HBsAg),antibody against hepatitis B surface antigen(anti-HBs),and antibody against hepatitis B core antigen(anti-HBc).Estimates of variance were determined using Taylor series linearization methods.Results The three serosurveys revealed decreases in the prevalence of HBsAg(7.19% in 2010 vs.6.51% in 2013 vs.5.87% in 2015)and anti-HBc positivity(43.89%vs.32.87%vs.28.46%)and an increase in the prevalence of anti-HBs positivity(49.07%vs.53.66%vs.53.72%)over time.From 2010 to 2015,the legally reported incidence of hepatitis B in Wuwei city decreased from 686.53/100,000 to 53.72/100,000.Notably,persistently high HBsAg-positive rates(above 5.40%)were observed among subjects aged 20–69 years old in the three serosurveys;the prevalence of HBsAg was above 1% among children younger than 10 years old.Furthermore,rural subjects had higher rates of HBsAg and anti-HBc positivity than their urban counterparts(6.04%vs.4.83% and 30.26%vs.20.35%,respectively)in 2015 but had a lower rate of anti-HBs positivity(49.68 vs.55.18%).Multivariate regression analysis showed that age,urban and rural areas,and education level were the main factors affecting HBV infection.Conclusion Although vaccine-based prevention and control measures reduced the rate of HBV infection in Wuwei City over time,the hepatitis B infection rate in children younger than 10 years was still higher than the national average level.Therefore,the prevention and control of mother-to-child transmission and the management of the infected should be the focus of future prevention and control work.展开更多
BACKGROUND: Hemodialysis (HD) patients are at high risk of infection by hepatitis B virus (HBV) or hepatitis C virus (HCV). The present study was designed to determine the impact of quality control measures on the pre...BACKGROUND: Hemodialysis (HD) patients are at high risk of infection by hepatitis B virus (HBV) or hepatitis C virus (HCV). The present study was designed to determine the impact of quality control measures on the prevention of transmission of blood-borne viruses. METHODS: A total of 6182 adult maintenance HD patients from all HD units in Zhejiang Province were recruited on January 1, 2007. The baseline demographic and clinical characteristics were recorded and all patients were followed up until death or survival at 4 years later. The Quality Control Standards of Hemodialysis were gradually implemented in HD units. The HBV or HCV seroconversion rates of the recruited patients were calculated and compared every year during the observation period. RESULTS: The prevalence of HBV was 8.3% at the beginning of the study, and 6.6% for HCV. With the implementation of the HD quality control measures, the HBV seroconversion rate tended to decrease year by year (χ 2 =6.620, P=0.085), and the HCV seroconversion rate decreased significantly (χ 2 =10.41, P=0.015). Compared with the data in 2007, the HBV seroconversion rate (χ 2 =4.204, P=0.040, relative risk ratio 0.393, 95% CI 0.156-0.991) and the HCV seroconversion rate (χ 2 =7.373, P=0.007, relative risk ratio 0.386, 95% CI 0.189-0.787) decreased significantly in 2010. CONCLUSION: Quality control measures for HD decreased the seroconversion rates of HBV or HCV in HD patients, showing that updated quality control measures reduce the risk for transmission of blood-borne viruses in the HD population.展开更多
[Objective] The aim was to analyze the current status and control measures of ecological restoration in Karst rocky desertification area of Guizhou.[Method] The current status and existing problems of ecological resto...[Objective] The aim was to analyze the current status and control measures of ecological restoration in Karst rocky desertification area of Guizhou.[Method] The current status and existing problems of ecological restoration in Karst rocky desertification area of Guizhou were studied firstly,and main control measures were put forward according to existing problems.[Result] At present,Karst rocky desertification area in Guizhou has suitable ecological environment,obvious control results and rich control experience,and there exist many problems like ambiguous concept of ecological restoration,biased control emphasis,single control measure and serious water shortage due to lagging engineering construction.Control measures mainly include combining natural restoration with artificial tending to speed up ecological restoration,reinforcing the restoration and rebuilding of development and construction project to prevent the deterioration of regional ecological environment,speeding up the construction of environmental friendly energy infrastructures to decrease the damage of vegetation by human activities,increasing industrial structure adjustment and greatly developing green industry and improving the investment in technological innovation to promote the rapid development of ecological restoration.[Conclusion] The study could provide scientific references for the ecological restoration in other Karst rocky desertification area in Southwest China.展开更多
In recent years,the occurrence of rice Chilo suppressalis( Walker) in Longyou County of Zhejiang Province has increased year by year and has become aggravated. This poses a great threat to the safety of rice productio...In recent years,the occurrence of rice Chilo suppressalis( Walker) in Longyou County of Zhejiang Province has increased year by year and has become aggravated. This poses a great threat to the safety of rice production. In order to curb the recurrence momentum of rice C. suppressalis,according to the dynamic monitoring and field system survey of rice C. suppressalis in Longyou County since 2015,the causes of the annual increase of rice C. suppressalis in recent years were analyzed,and the recurrence area of C. suppressalis was introduced,and finally some prevention and control measures were put forward.展开更多
Based on the analysis of current situation of water environment in the Chaohu Lake,general ideas and measures of controlling the water environment were proposed. In respect of control ideas,controlling outbreaks of bl...Based on the analysis of current situation of water environment in the Chaohu Lake,general ideas and measures of controlling the water environment were proposed. In respect of control ideas,controlling outbreaks of blue-green algae should be as one of control goals; it is needed to combine reducing the quantity of blue-green algae with decreasing eutrophication level to make the decrease in the quantity of blue-green algae larger than their natural increase until outbreaks of blue-green algae are eliminated; all kinds of techniques should be combined closely,integrated and innovated,and corresponding safeguard measures should be adopted. In respect of control measures,controlling sources of pollution and intercepting pollutants are basic measures,of which improving sewage treatment capacity and standard greatly is a key measure,and actively controlling pollution from large-scale livestock and poultry breeding is one of main measures; rivers polluted heavily should be controlled,and using microorganisms to purify small and moderate rivers can be as one of preferred techniques; blue-green algae should be dredged deeply to reducing their quantity; water should be transferred from the Yangtze River to the Chaohu Lake or the Hauihe River to purify water bodies and increase environmental capacity; reed wetland should be restored on a large scale to increase vegetation coverage from 5% to 20%; dredging should be combined with the elevation of basement of restored reed wetland.展开更多
Environmental pollution problem generated in dairy farming process is the bottleneck restricting development of animal husbandry. By using the investigation data from dairy farmers of Inner Mongolia,environmental poll...Environmental pollution problem generated in dairy farming process is the bottleneck restricting development of animal husbandry. By using the investigation data from dairy farmers of Inner Mongolia,environmental pollution problem generated by dairy farming in Inner Mongolia and its cause were analyzed,and prevention and control measures were put forward. The research result showed that weak technology support of environmental treatment and environmental-protection awareness of dairy farmer and bad application effect of pollution control technology caused by lower education degree of dairy farmer were main reasons for environmental pollution problem. We should develop dairy circular economy,advocate a moderate scale,scientifically breed,and enhance training of pollution control technology and propaganda to protect environment.展开更多
Sweet potato virus disease is a serious biological threat to sweet potato,which seriously affects the development of sweet potato industry in China.This paper gives a brief introduction to the main defensive measures ...Sweet potato virus disease is a serious biological threat to sweet potato,which seriously affects the development of sweet potato industry in China.This paper gives a brief introduction to the main defensive measures of sweet potato virus disease,such as cutting of virus infection source,killing of viral transmission media,cultivation and application of virus-free sweet potato,use of antiviral agents,breeding of varieties with virus resistance,and mild strain cross protection,so as to provide some reference for this field.展开更多
With the development of strawberry protected cultivation industry, continuous cropping of strawberry is becoming more and more com-mon, and soil-borne diseases are increasingly severe. The paper introduces damage symp...With the development of strawberry protected cultivation industry, continuous cropping of strawberry is becoming more and more com-mon, and soil-borne diseases are increasingly severe. The paper introduces damage symptoms, pathogenic bacteria and transmission mode of several main root diseases of strawberry, including Verticillium wilt, Fusarium wilt, root rot and bacterial wilt, and put forward corresponding prevention and control measures.展开更多
Tuberculosis is one of the most important infectious diseases in our country. Also nosocomial infection by tuberculosis can occur, which can be prevented by implementing simple, effective and affordable tuberculosis i...Tuberculosis is one of the most important infectious diseases in our country. Also nosocomial infection by tuberculosis can occur, which can be prevented by implementing simple, effective and affordable tuberculosis infection control measures in health care facilities. To evaluate the effectiveness of infection control measures, such study was planned. Questionnaires were administered to all doctors, healthcare workers and servants working in outdoor and indoor department of tuberculosis at tertiary care hospital to assess the knowledge, attitudes and practices on prevention and control of Tuberculosis infection. A scoring system was devised to grade them. One-time audit was also done in outpatient and inpatient department. The analysis showed scoring of poor for doctors, good for nurses and poor forward aids. There is a need to develop strategies for training of health care workers on regular basis in order to reduce the incidence of nosocomial infections. Audit result shows a good level of environmental control measures. Better knowledge, attitude and practices are helpful for the prevention and control of tuberculosis. Also environmental control measures are helpful to prevent infection.展开更多
We present a novel feedback control method for quantum systems.Feedback does not affect the controlled system itself.Instead,it controls the unravelling of the quantum channel of interaction between the system and its...We present a novel feedback control method for quantum systems.Feedback does not affect the controlled system itself.Instead,it controls the unravelling of the quantum channel of interaction between the system and its environment.This interaction can be represented as a history of events.If their informational content is changed,their back-action on the system is also modified.Feedback action is trigged by the events,thus granting the system the degree of control over its own state.The efficiency of the proposed scheme is demonstrated on the example of two-mode atomic Bose-Einstein condensate,with one of its modes subject to phase-contrast imaging in a Mach–Zehnder interferometer.The histories of photocounts in the output channels of the interferometer are used for feedback.Its capabilities of state engineering are studied for different settings of the feedback loop and different numbers of events in the recorded histories.展开更多
文摘Deep foundation pit excavation is a basic and key step involved in modern building construction.In order to ensure the construction quality and safety of deep foundation pits,this paper takes a project as an example to analyze deep foundation pit excavation technology,including the nature of this construction project,the main technical measures in the construction of deep foundation pit,and the analysis of the safety risk prevention and control measures.The purpose of this analysis is to provide scientific reference for the construction quality and safety of deep foundation pits.
基金supported by Shanghai Pujiang Program (No.2019PJC062)the Natural Science Foundation of Shandong Province (No.ZR2021MG003)the Research Project on Undergraduate Teaching Reform of Higher Education in Shandong Province (No.Z2021046).
文摘The purpose of this study is to reduce the uncertainty in the calculation process on hesitant fuzzy sets(HFSs).The innovation of this study is to unify the cardinal numbers of hesitant fuzzy elements(HFEs)in a special way.Firstly,a probability density function is assigned for any given HFE.Thereafter,equal-probability transformation is introduced to transform HFEs with different cardinal numbers on the condition into the same probability density function.The characteristic of this transformation is that the higher the consistency of the membership degrees in HFEs,the higher the credibility of the mentioned membership degrees is,then,the bigger the probability density values for them are.According to this transformation technique,a set of novel distance measures on HFSs is provided.Finally,an illustrative example of intersection traffic control is introduced to show the usefulness of the given distance measures.The example also shows that this study is a good complement to operation theories on HFSs.
文摘Introduction: The management of hypertension is mostly based on pharmacotherapy and hygienic and dietary measures (HDMs) for which little data is available in Cameroon. The concern to improve the quality of life of hypertensive patients led us to study the knowledge, compliance and effect of HDMs among Cameroonian hypertensive patients. Methods: This was a cross-sectional study carried out at the Douala General Hospital;the census of patients was carried out from 05 March to 10 May 2018. The data evaluated were knowledge and compliance with HDMs with an inference of their effect on blood pressure control. Results: We recruited 330 participants at mean age of 60 ± 11 years, 37.9% men;57.3% with blood pressure (BP) controlled. Out of 330 subjects, 308 (93.3%) who had been educated about dietary health measures for hypertension were assessed on knowledge, compliance and effect of these measures against 22 (6.7%) who had never heard about them. Around 85.7% of participants had good knowledge of HDMs and 78.9% had good compliance with them. There was no statistically significant influence of knowledge and compliance with HDMs on blood pressure control. Conclusion: The level of knowledge and adherence to HDMs of hypertensive patients at the Douala General Hospital was appreciable. It is however appropriate for physicians to intensify patient education on HDMs and BP control.
文摘Based on practical work experience,this paper analyzed the occurrence characteristics and control measures of Spodoptera frugiperda in maize.The measures including forecasting and early warning,regional prevention and control,agricultural prevention and control,physical prevention and control,chemical prevention and control,and biological prevention and control can effectively control the damage of S.frugiperda and guarantee the safety of food production.The results will provide some reference for the prevention and control of S.frugiperda.
文摘The Jinping I hydropower station is a huge water conservancy project consisting of the highest concrete arch dam to date in the world and a highly complex and large underground powerhouse cavern. It is located on the right bank with extremely high in-situ stress and a few discontinuities observed in surrounding rock masses. The problems of rock mass deformation and failure result in considerable challenges related to project design and construction and have raised a wide range of concerns in the fields of rock mechanics and engineering. During the excavation of underground caverns, high in-situ stress and relatively low rock mass strength in combination with large excavation dimensions lead to large deformation of the surrounding rock mass and support. Existing experiences in excavation and support cannot deal with the large deformation of rock mass effectively, and further studies are needed. In this paper, the geological conditions, layout of caverns, and design of excavation and support are first introduced, and then detailed analyses of deformation and failure characteristics of rocks are presented. Based on this, the mechanisms of deformation and failure are discussed, and the support adjustments for controlling rock large deformation and subsequent excavation procedures are proposed. Finally, the effectiveness of support and excavation adjustments to maintain the stability of the rock mass is verified. The measures for controlling the large deformation of surrounding rocks enrich the practical experiences related to the design and construction of large underground openings, and the construction of caverns in the Jinping I hydropower station provides a good case study of large-scale excavation in highly stressed ground with complex geological structures, as well as a reference case for research on rock mechanics.
基金The authors are grateful for the financial support from the National Natural Science Foundation of China(No.51827901&No.52274133)the Program for Guangdong Introducing Innovative and Enterpreneurial Teams(No.2019ZT08G315)the Shenzhen National Science Fund for Distinguished Young Scholars(RCJC20210706091948015).
文摘In-situ pressure-preserved coring(IPP-Coring)is considered to be the most reliable and efficient method for the identification of the scale of oil and gas resources.During IPP-Coring,because the rotation behavior of the pressure controller valve cover in different medium environments is unclear,interference between the valve cover and inner pipe may occur and negatively affect the IPP-Coring success rate.To address this issue,we conducted a series of indoor experiments employing a high-speed camera to gain greater insights into the valve cover rotation behavior in different medium environments,e.g.,air,water,and simulated drilling fluids.The results indicated that the variation in the valve cover rotation angle in the air and fluid environments can be described by a one-phase exponential decay function with a constant time parameter and by biphasic dose response function,respectively.The rotation behavior in the fluid environments exhibited distinct elastic and gravitational acceleration zones.In the fluid environments,the density clearly impacted the valve cover closing time and rotation behavior,whereas the effect of viscosity was very slight.This can be attributed to the negligible influence of the fluid viscosity on the drag coefficient found in this study;meanwhile,the density can increase the buoyancy and the time period during which the valve cover experienced a high drag coefficient.Considering these results,control schemes for the valve cover rotation behavior during IPP-Coring were proposed for different layers and geological conditions in which the different drilling fluids should be used,e.g.,the use of a high-density valve cover in high-pore pressure layers.
基金This work was supported by the National Natural Science Foundation of China(31971731,41771121)the Xinjiang National Key Research and Development Program(2019B00005)+1 种基金the National Key Research and Development Program(2017YFC0506705)the Youth Innovation Promotion Association of Chinese Academy of Sciences(2017476).
文摘Desertification is one of the most serious environmental problems in the world,especially in the arid desert regions.Combating desertification,therefore,is an urgent task on a regional or even global scale.The Taklimakan Desert in China is the second largest mobile desert in the world and has been called the''Dead Sea''due to few organisms can exist in such a harsh environment.The Taklimakan Desert Highway,the longest desert highway(a total length of 446 km)across the mobile desert in the world,was built in the 1990s within the Taklimakan Desert.It has an important strategic significance regarding oil and gas resources exploration and plays a vital role in the socio-economic development of southern Xinjiang,China.However,wind-blow sand seriously damages the smoothness of the desert highway and,in this case,mechanical sand control system(including sand barrier fences and straw checkerboards)was used early in the life of the desert highway to protect the road.Unfortunately,more than 70%of the sand barrier fences and straw checkerboards have lost their functions,and the desert highway has often been buried and frequently blocked since 1999.To solve this problem,a long artificial shelterbelt with the length of 437 km was built along the desert highway since 2000.However,some potential problems still exist for the sustainable development of the desert highway,such as water shortage,strong sandstorms,extreme environmental characteristics and large maintenance costs.The study aims to provide an overview of the damages caused by wind-blown sand and the effects of sand control measures along the Taklimakan Desert Highway.Ultimately,we provide some suggestions for the biological sand control system to ensure the sustainable development of the Taklimakan Desert Highway,such as screening drought-resistant species to reduce the irrigation requirement and ensure the sound development of groundwater,screening halophytes to restore vegetation in the case of soil salinization,and planting cash crops,such as Cistanche,Wolfberry,Apocynum and other cash crops to decrease the high cost of maintenance on highways and shelterbelts.
基金This work was supported by the foundation of Key Research and Development Program of Hubei Province(2020BAB137)Shen-zhen Fundamental Research Program(JCYJ20210324142007022).
文摘In-situ layerwise imaging measurement of laser powder bed fusion(LPBF)provides a wealth of forming and defect data which enables monitoring of components quality and powder bed homogeneity.Using high-resolution camera layerwise imaging and image processing algorithms to monitor fusion area and powder bed geometric defects has been studied by many researchers,which successfully monitored the contours of components and evaluated their accuracy.However,research for the methods of in-situ 3D contour measurement or component edge warping identification is rare.In this study,a 3D contour mea-surement method combining gray intensity and phase difference is proposed,and its accuracy is verified by designed experiments.The results show that the high-precision of the 3D contours can be achieved by the constructed energy minimization function.This method can detect the deviations of common ge-ometric features as well as warpage at LPBF component edges,and provides fundamental data for in-situ quality monitoring tools.
基金National Natural Science Foundation of China(Nos.61871353,62031005)。
文摘In-situ measurement of internal solitary waves(ISWs)is complicated in the ocean due to their randomness.At present,the ISWs are mainly detected by the chain structure of conductivity-temperature-depth systems(CTDs)or temperature sensors.The high cost limits the spatial resolution,which ultimately affects the measuring accuracy of the ISW amplitude.In this paper,we developed an experimental measurement system for detecting ISWs based on the stimulated Raman scattering in distributed optical fibers.This system has the advantages of high precision,low cost,and easy operation.The experimental results show that the system is consistent with CTDs in the measurement of vertical ocean temperature variation.The spatial resolution of the system can reach 1.0 m and the measuring accuracy of temperature is 0.2℃.We successfully detected 3 ISWs by the system in the South China Sea and two optical remote sensing images collected on May 18,2021,the same day of two detected ISWs,verify the occurrence of the measured ISWs.We used the image pairs method to calculate the phase velocity of ISW and the result is 1.71 ms^(-1).By extracting the distances between wave packets,it can be found that the semi-diurnal tide generates the detected ISWs.The impact of the tidal current velocity on the ISW in amplitude is undeniable.Undoubtedly,the system has a great application prospect for detecting ISWs and other dynamic phenomena in the ocean.
基金supported by the China Special Grant for the Prevention and Control of Infectious Diseases[2012ZX10004907,2017ZX10105011]Natural Science Foundation of China[81473026]。
文摘Objective Despite the remarkable progress in efforts to control disease spread,the nationwide elimination of hepatitis B in China is still hindered by the persistently high rate of hepatitis B virus(HBV)infection in Western China.This study aimed to evaluate the strategy of hepatitis B prevention and control in Western China and identify potential areas and strategies for improvement.Methods Susceptible population vaccination,health education,professional training of doctors,and other prevention and control measures have been implemented in Wuwei city since 2010.Data were obtained from three representative cross-sectional serosurveys conducted in 2010,2013,and 2015.The serum samples were subjected to enzyme-linked immunosorbent assays to detect the following seromarkers:HBV surface antigen(HBsAg),antibody against hepatitis B surface antigen(anti-HBs),and antibody against hepatitis B core antigen(anti-HBc).Estimates of variance were determined using Taylor series linearization methods.Results The three serosurveys revealed decreases in the prevalence of HBsAg(7.19% in 2010 vs.6.51% in 2013 vs.5.87% in 2015)and anti-HBc positivity(43.89%vs.32.87%vs.28.46%)and an increase in the prevalence of anti-HBs positivity(49.07%vs.53.66%vs.53.72%)over time.From 2010 to 2015,the legally reported incidence of hepatitis B in Wuwei city decreased from 686.53/100,000 to 53.72/100,000.Notably,persistently high HBsAg-positive rates(above 5.40%)were observed among subjects aged 20–69 years old in the three serosurveys;the prevalence of HBsAg was above 1% among children younger than 10 years old.Furthermore,rural subjects had higher rates of HBsAg and anti-HBc positivity than their urban counterparts(6.04%vs.4.83% and 30.26%vs.20.35%,respectively)in 2015 but had a lower rate of anti-HBs positivity(49.68 vs.55.18%).Multivariate regression analysis showed that age,urban and rural areas,and education level were the main factors affecting HBV infection.Conclusion Although vaccine-based prevention and control measures reduced the rate of HBV infection in Wuwei City over time,the hepatitis B infection rate in children younger than 10 years was still higher than the national average level.Therefore,the prevention and control of mother-to-child transmission and the management of the infected should be the focus of future prevention and control work.
基金supported by grants from Zhejiang Health Bureau (2008B073)Zhejiang Education Bureau (Y200909640)
文摘BACKGROUND: Hemodialysis (HD) patients are at high risk of infection by hepatitis B virus (HBV) or hepatitis C virus (HCV). The present study was designed to determine the impact of quality control measures on the prevention of transmission of blood-borne viruses. METHODS: A total of 6182 adult maintenance HD patients from all HD units in Zhejiang Province were recruited on January 1, 2007. The baseline demographic and clinical characteristics were recorded and all patients were followed up until death or survival at 4 years later. The Quality Control Standards of Hemodialysis were gradually implemented in HD units. The HBV or HCV seroconversion rates of the recruited patients were calculated and compared every year during the observation period. RESULTS: The prevalence of HBV was 8.3% at the beginning of the study, and 6.6% for HCV. With the implementation of the HD quality control measures, the HBV seroconversion rate tended to decrease year by year (χ 2 =6.620, P=0.085), and the HCV seroconversion rate decreased significantly (χ 2 =10.41, P=0.015). Compared with the data in 2007, the HBV seroconversion rate (χ 2 =4.204, P=0.040, relative risk ratio 0.393, 95% CI 0.156-0.991) and the HCV seroconversion rate (χ 2 =7.373, P=0.007, relative risk ratio 0.386, 95% CI 0.189-0.787) decreased significantly in 2010. CONCLUSION: Quality control measures for HD decreased the seroconversion rates of HBV or HCV in HD patients, showing that updated quality control measures reduce the risk for transmission of blood-borne viruses in the HD population.
文摘[Objective] The aim was to analyze the current status and control measures of ecological restoration in Karst rocky desertification area of Guizhou.[Method] The current status and existing problems of ecological restoration in Karst rocky desertification area of Guizhou were studied firstly,and main control measures were put forward according to existing problems.[Result] At present,Karst rocky desertification area in Guizhou has suitable ecological environment,obvious control results and rich control experience,and there exist many problems like ambiguous concept of ecological restoration,biased control emphasis,single control measure and serious water shortage due to lagging engineering construction.Control measures mainly include combining natural restoration with artificial tending to speed up ecological restoration,reinforcing the restoration and rebuilding of development and construction project to prevent the deterioration of regional ecological environment,speeding up the construction of environmental friendly energy infrastructures to decrease the damage of vegetation by human activities,increasing industrial structure adjustment and greatly developing green industry and improving the investment in technological innovation to promote the rapid development of ecological restoration.[Conclusion] The study could provide scientific references for the ecological restoration in other Karst rocky desertification area in Southwest China.
文摘In recent years,the occurrence of rice Chilo suppressalis( Walker) in Longyou County of Zhejiang Province has increased year by year and has become aggravated. This poses a great threat to the safety of rice production. In order to curb the recurrence momentum of rice C. suppressalis,according to the dynamic monitoring and field system survey of rice C. suppressalis in Longyou County since 2015,the causes of the annual increase of rice C. suppressalis in recent years were analyzed,and the recurrence area of C. suppressalis was introduced,and finally some prevention and control measures were put forward.
文摘Based on the analysis of current situation of water environment in the Chaohu Lake,general ideas and measures of controlling the water environment were proposed. In respect of control ideas,controlling outbreaks of blue-green algae should be as one of control goals; it is needed to combine reducing the quantity of blue-green algae with decreasing eutrophication level to make the decrease in the quantity of blue-green algae larger than their natural increase until outbreaks of blue-green algae are eliminated; all kinds of techniques should be combined closely,integrated and innovated,and corresponding safeguard measures should be adopted. In respect of control measures,controlling sources of pollution and intercepting pollutants are basic measures,of which improving sewage treatment capacity and standard greatly is a key measure,and actively controlling pollution from large-scale livestock and poultry breeding is one of main measures; rivers polluted heavily should be controlled,and using microorganisms to purify small and moderate rivers can be as one of preferred techniques; blue-green algae should be dredged deeply to reducing their quantity; water should be transferred from the Yangtze River to the Chaohu Lake or the Hauihe River to purify water bodies and increase environmental capacity; reed wetland should be restored on a large scale to increase vegetation coverage from 5% to 20%; dredging should be combined with the elevation of basement of restored reed wetland.
文摘Environmental pollution problem generated in dairy farming process is the bottleneck restricting development of animal husbandry. By using the investigation data from dairy farmers of Inner Mongolia,environmental pollution problem generated by dairy farming in Inner Mongolia and its cause were analyzed,and prevention and control measures were put forward. The research result showed that weak technology support of environmental treatment and environmental-protection awareness of dairy farmer and bad application effect of pollution control technology caused by lower education degree of dairy farmer were main reasons for environmental pollution problem. We should develop dairy circular economy,advocate a moderate scale,scientifically breed,and enhance training of pollution control technology and propaganda to protect environment.
基金Supported by Hunan Agricultural Science and Technology Innovation Fund(2017XC13)Changsha Sweet Potato Engineering and Technology Research Center(kq1701024)+1 种基金Hunan Sweet Potato Engineering and Technology Research Center(2018TP2032)China Agriculture Research System of Sweet Potato(CARS-11-C-16)
文摘Sweet potato virus disease is a serious biological threat to sweet potato,which seriously affects the development of sweet potato industry in China.This paper gives a brief introduction to the main defensive measures of sweet potato virus disease,such as cutting of virus infection source,killing of viral transmission media,cultivation and application of virus-free sweet potato,use of antiviral agents,breeding of varieties with virus resistance,and mild strain cross protection,so as to provide some reference for this field.
基金Supported by Natural Science Foundation of Shandong Province(ZR2018LC002)Key Research and Development Plan of Shandong Province(2018JHZ003)Youth Fund of Shandong Academy of Agricultural Sciences(2016YQN31)。
文摘With the development of strawberry protected cultivation industry, continuous cropping of strawberry is becoming more and more com-mon, and soil-borne diseases are increasingly severe. The paper introduces damage symptoms, pathogenic bacteria and transmission mode of several main root diseases of strawberry, including Verticillium wilt, Fusarium wilt, root rot and bacterial wilt, and put forward corresponding prevention and control measures.
文摘Tuberculosis is one of the most important infectious diseases in our country. Also nosocomial infection by tuberculosis can occur, which can be prevented by implementing simple, effective and affordable tuberculosis infection control measures in health care facilities. To evaluate the effectiveness of infection control measures, such study was planned. Questionnaires were administered to all doctors, healthcare workers and servants working in outdoor and indoor department of tuberculosis at tertiary care hospital to assess the knowledge, attitudes and practices on prevention and control of Tuberculosis infection. A scoring system was devised to grade them. One-time audit was also done in outpatient and inpatient department. The analysis showed scoring of poor for doctors, good for nurses and poor forward aids. There is a need to develop strategies for training of health care workers on regular basis in order to reduce the incidence of nosocomial infections. Audit result shows a good level of environmental control measures. Better knowledge, attitude and practices are helpful for the prevention and control of tuberculosis. Also environmental control measures are helpful to prevent infection.
基金This work was supported by the State order(Project AAAA-A21-121021800168-4)at the Institute of Automation and Electrometry SB RAS.
文摘We present a novel feedback control method for quantum systems.Feedback does not affect the controlled system itself.Instead,it controls the unravelling of the quantum channel of interaction between the system and its environment.This interaction can be represented as a history of events.If their informational content is changed,their back-action on the system is also modified.Feedback action is trigged by the events,thus granting the system the degree of control over its own state.The efficiency of the proposed scheme is demonstrated on the example of two-mode atomic Bose-Einstein condensate,with one of its modes subject to phase-contrast imaging in a Mach–Zehnder interferometer.The histories of photocounts in the output channels of the interferometer are used for feedback.Its capabilities of state engineering are studied for different settings of the feedback loop and different numbers of events in the recorded histories.