In recent years,the incidence rate of stroke has increased year by year.Post stroke depres‐sion is one of its main complications,which seriously affects the recovery of physiological functions and quality of life of ...In recent years,the incidence rate of stroke has increased year by year.Post stroke depres‐sion is one of its main complications,which seriously affects the recovery of physiological functions and quality of life of stroke patients.Traditional Chinese medicine has signifi‐cant therapeutic effects in treating this disease.This article provides a classification and review of traditional Chinese medicine treatment methods for post-stroke depression,and looks forward to the current problems.展开更多
Asphalt mow strips are typically used as vegetation barriers around guardrail posts in the design of roadside safety structures. Asphalt mow strips have historically been modeled as a rigid layer in simulations;this a...Asphalt mow strips are typically used as vegetation barriers around guardrail posts in the design of roadside safety structures. Asphalt mow strips have historically been modeled as a rigid layer in simulations;this assumption results in significant ground level restraint on the guardrail post. However, experiments have shown that asphalt rupture should be considered in the analysis of the response of guardrail posts embedded in mow strips. The present study investigates the effect of asphalt material properties and mow strip geometry on guardrail post performance using finite element simulations. Numerical simulations are performed and correlated with results from static experiments and material testing. The test simulations and experimental results are used to evaluate the response of guardrail posts with various mow strip designs to predict the level of restraint from the asphalt layer. The model is then used to investigate the effects of asphalt material properties and mow strip geometry on the overall performance of the system. The results demonstrate that including asphalt rupture in numerical simulations is essential in accurately predicting the behavior of guardrail posts installed in asphalt mow strips. In addition, mow strip geometry along with asphalt material properties significantly affect the guardrail post response.展开更多
Sina Weibo,an online social network site,has gained popularity but lost it in recent years.Now we are still curious on the number of posts in Sina Weibo in its golden age.Besides checking this number in Sina’s operat...Sina Weibo,an online social network site,has gained popularity but lost it in recent years.Now we are still curious on the number of posts in Sina Weibo in its golden age.Besides checking this number in Sina’s operating results,we aim to estimate and verify this number through measurement by using statistical techniques.Existing approaches on measurement always rely on the supported streaming application programming interface(API)which provides proportional sampling.However no such API is available for Sina Weibo.Instead,Sina provides a public timeline API which provides non-proportional sampling but always returns a(nearly)fixed number of s amples.In this paper,we present a novel method utilizing this API and estimate the number of posts in Sina Weibo in its golden age.展开更多
This paper aims to standardize health, safety and environment(HSE) training matrices for effectively identifying training requirements and enhancing job competency of grassroots posts in petroleum and petrochemical ...This paper aims to standardize health, safety and environment(HSE) training matrices for effectively identifying training requirements and enhancing job competency of grassroots posts in petroleum and petrochemical enterprises. After an investigation into HSE training performance in petroleum and petrochemical enterprises, HSE training matrices templates for 239 grassroots posts involving 22 primary petroleum and petrochemical disciplines were developed based on the technical requirements of HSE training matrices templates and the studies of template development processes and technical methods at grassroots level. Applications of these templates in 12 companies demonstrate their effectiveness in improving HSE training and management for grassroots posts,strengthening risk control and promoting the application of HSE system and tools in grassroots units.展开更多
The research examines the way in which members of the U.S. House of Representative represent themselves on the social network site Facebook. Each member’s activity is observed on seven different occasions and the fre...The research examines the way in which members of the U.S. House of Representative represent themselves on the social network site Facebook. Each member’s activity is observed on seven different occasions and the frequency and substantive character of posts made during the second half of 2013 are established. The focus is on position-taking posts versus posts which mention the district the member serves in. Our expectation is that members from electorally safe districts will be more likely to advertise their policy positions while members from marginal districts will be more inclined to advertise their district connections. We control for minority party status, gender, and ideological extremism among other concerns and learn electoral safety is a good predictor of both “position-taking” and “district mentions”. Consistent with an electoral motive, we also find members from the minority party less likely to take positions on the issues of the day and more likely to mention the district they serve in.展开更多
In the last few decades, the impacts of human activities on ecosystem have rapidly increased resulting to detrimental ecosystem changes. Human-wildlife conflict (HWC) is one of the greatest consequences of human impac...In the last few decades, the impacts of human activities on ecosystem have rapidly increased resulting to detrimental ecosystem changes. Human-wildlife conflict (HWC) is one of the greatest consequences of human impacts on the environment. Although HWC has been there for decades, its intensity seems to be growing with the spread of human settlements, changes in land use patterns and diminishing suitable natural habitats for wildlife. To mitigate HWC, various strategies have been devised and implemented. This study focused on predator-proof bomas (PPBs) approach that is ongoing in Amboseli ecosystem. The aim was to establish reasons behind the slow adoptions of the recycled plastics poles by owners of PPBs that were constructed using wooden posts between the years 2010 to 2013. Randomly selected 36 PPB homestead owners were interviewed and the physical structures of their PPBs assessed. Results revealed a positive relationship between PPB size and number of poles damaged;and a significant association between the damaged posts and the number of indigenous posts replaced in the three group ranches (X2 = 34.9331, df = 2, p < 0.05). Most of the respondents (89%) cited posts and doors (72%) as the main parts that needed repairs. About 80% of the respondents would recommend the plastic posts for use in constructing new PPBs by other people. Most of the PPB beneficiaries whose PPBs were constructed in 2010-2013 have opted for an “easy” alternative source of posts from the sparsely distrusted trees around their homesteads. It is recommend that an open window period should be tried to entice the wooden post PPBs owners to adopt the recycled plastic posts. This may necessitate upgrading the existing old wooden bomas to a “smart PPBs”. It is suggested that the “smart PPBs” should not only have recycled plastic posts but also “free” energy saving stoves in each household to reduce the level of deforestation.展开更多
This study aimed to evaluate the influence of quartz fiber post placement on the fracture resistance of endodontically treated premolars with different dental defects under dynamic loading.Fifty extracted single-roote...This study aimed to evaluate the influence of quartz fiber post placement on the fracture resistance of endodontically treated premolars with different dental defects under dynamic loading.Fifty extracted single-rooted mandibular premolars were randomized into five groups.Each group was prepared according to numbers of residual walls ranged from 0 to 4.Then each group was divided into two subgroups with one restored with quartz fiber posts and the other without posts.In no-post groups,gutta percha point 2 mm below cemento-enamel junction was removed.Composite resin was adapted to the well and used to shape the core directly.Each tooth was restored with a complete metal crown.Dynamic loading was carried out in a masticatory simulator with a nominal load of 50 N at 2 Hz for 300 000 loading cycles.Then a quasi-statically load was applied in a universal testing machine 306 to the long axis with a crosshead speed of 1 mm?min21until fracture.Data were analyzed with one-way analysis of variance and pairwise comparison(P,0.05).No specimens failed during dynamic loading.The fracture resistance enhanced with the increase of numbers of coronal walls and the differences were significant(P,0.05).Placement of fiber posts had a significant effect when fewer than two walls remained(P,0.05),but it had no significant influence in groups with two,three or four walls(P.0.05).Fiber post did not change failure mode,and the fracture pattern was mainly favorable.More dentin walls need to be retained in clinic.When no less than two walls remained,a fiber post is not always necessary.展开更多
The aim of this study is to investigate the influence of different posts on the fracture mechanics of endodontically-treated teeth with open apex. Forty-eight human maxillary anterior teeth were collected, and the roo...The aim of this study is to investigate the influence of different posts on the fracture mechanics of endodontically-treated teeth with open apex. Forty-eight human maxillary anterior teeth were collected, and the root was transversely sectioned 12 mm under the cementoenamal junction (CEJ). These samples were then randomly divided into two groups, i.e., minor diameter open apex root (group A) and major diameter open apex root (group B), with mineral trioxide aggregate (MTA) placed into the apical 4 mm in the root canals. Subsequently, both groups were respectively further divided into three subgroups as follows: fiber-post (subgroup 1), metal post (subgroup 2) and non-post (subgroup 3) group. Teeth were restored with a composite resin crown and tested by using a universal testing machine at the rate of 1 mm/min cross-head. Values of the maximum fracture resistance and failure patterns were recorded and compared among all subgroups. In addition, the changes of MTA properties were carefully examined via X-ray photography. Our results indicate that (1) In group A, the mean value of fracture resistance for teeth restored with fiber posts were statistically higher than that with either metal post or non-post; (2) In group B, there was no statistically significant difference in the mean value of fracture resistance among three subgroups; (3) No statistical significance in the mean value of fracture resistance was found between group A and group B; (4) The failure modes of most samples (58%) were irreparable; (5) MTA in two teeth developed cracks after loading tests. In conclusion, endodontically-treated teeth restored with fiber posts are more resistant to fracture than those restored with either metal posts or non-post, and most of the fracture modes are catastrophic in nature.展开更多
A cradle-to-grave life cycle assessment is done to identify the environmental impacts of chromated copper arsenate (CCA)-treated timber used for highway guard rail posts, to understand the processes that contribute to...A cradle-to-grave life cycle assessment is done to identify the environmental impacts of chromated copper arsenate (CCA)-treated timber used for highway guard rail posts, to understand the processes that contribute to the total impacts, and to determine how the impacts compare to the primary alternative product, galvanized steel posts. Guard rail posts are the supporting structures for highway guard rails. Transportation engineers, as well as public and regulatory interests, have increasing need to understand the environmental implications of guard rail post selection, in addition to factors such as costs and service performance. This study uses a life cycle inventory (LCI) to catalogue the input and output data from guard rail post manufacture, service life, and disposition, and a life cycle impact assessment (LCIA) to assess anthropogenic and net greenhouse gas (GHG), acidification, smog, ecotoxicity, and eutrophication potentially resulting from life cycle air emissions. Other indicators of interest also are tracked, such as fossil fuel and water use. Comparisons of guard rail post products are made at a functional unit of one post per year of service. This life cycle assessment (LCA) finds that the manufacture, use, and disposition of CCA-treated wood guard rails offers lower fossil fuel use and lower anthropogenic and net GHG emissions, acidification, smog potential, and ecotoxicity environmental impacts than impact indicator values for galvanized steel posts. Water use and eutrophication impact indicator values for CCA-treated guard rail posts are greater than impact indicator values for galvanized steel guard rail posts.展开更多
The effects of different post-space pretreatments on the retentive force of fiber posts cemented with a self-adhesive resin cement were investigated. Twenty-eight single-canal premolars were obturated by Resilon using...The effects of different post-space pretreatments on the retentive force of fiber posts cemented with a self-adhesive resin cement were investigated. Twenty-eight single-canal premolars were obturated by Resilon using warm vertical compaction and treated with distilled water, 2.5% NaOCl, 17% EDTA and 2.5% NaOCI; or 17% EDTA, 2.5% NaOCI, and ultrasonic agitation (U/E/N treatment). Subsequently, radicular dentin surfaces were observed under scanning electron microscopy (SEM). RelyX Fiber Posts were cemented in the treated canals by using RelyX U100, and thin-slice push-out test and SEM observation of coronal and apical regions of the specimens were performed. Data were analyzed using two-way ANOVA and Tukey's HSD post- hoc tests, and the percentage of failure type was calculated. Ultrasonic/EDTA/NaOC1 irrigation showed the maximum effectiveness in removing the smear layer and debris on the dentin surface. The apical bond strength of the experimental groups was significantly higher than that of the control group (P〈 0.05). Adhesive failure between cement and dentin was the most common mode of failure. No obvious RDIZ or resin tag was detected. Chemical irrigants facilitated the bonding of these fiber posts, and ultrasonic activation improved retention. Future studies should evaluate the effectiveness of irrigation on fiber post push-out strength in fatigue cycling condition.展开更多
For years,non-structural masonry walls have received little attention by code developers and professional engineers.Recently,significant efforts have been made to shed more light on out-of-plane(OOP)behavior of non-st...For years,non-structural masonry walls have received little attention by code developers and professional engineers.Recently,significant efforts have been made to shed more light on out-of-plane(OOP)behavior of non-structural masonry walls.In updated provisions of the Iranian seismic code,bed joint reinforcements(BJRs)and steel wallposts have been suggested for use.BJRs are horizontal reinforcements;steel wallposts are vertical truss-like elements intended to provide additional OOP restraints for a wall.The contribution of BJRs has previously been investigated by the authors.This study is devoted to investigating the contribution of steel wallposts to the OOP behavior of non-structural masonry walls.Using pre-validated 3D finite element(FE)models,the OOP behavior of 180 non-structural masonry walls with varying configurations and details are investigated.The OOP pressure-displacement curve,ultimate strength,the response modification factor,and the cracking pattern are among the results presented in this study.It is found that steel wallposts,especially those with higher rigidity,can improve the OOP strength of the walls.The contribution of wallposts in the case of shorter length walls and walls with an opening are more pronounced.Results also indicate that masonry walls with wallpost generally have smaller modification factors compared to similar walls without wallpost.展开更多
Using the rigid visco-plastic Finite Element Method (FEM), the process offorging for long cone-shaped posts made of aluminum alloys was modeled and the correspondingdistributions of the field variables were obtained b...Using the rigid visco-plastic Finite Element Method (FEM), the process offorging for long cone-shaped posts made of aluminum alloys was modeled and the correspondingdistributions of the field variables were obtained based on considering aberrance of grids, dynamicboundary conditions, non-stable process, coupled thermo-mechanical behavior and other specialproblems. The difficulties in equipment selection and die analysis caused by the long cone shape ofpost, as well as by pressure calculation were solved.展开更多
A novel H-plane cross-shaped circulator based on magneto-photonic crystals is experimentally investigated.The band gap of the TE mode for the photonic crystals is calculated by the plane wave expansion method.The tran...A novel H-plane cross-shaped circulator based on magneto-photonic crystals is experimentally investigated.The band gap of the TE mode for the photonic crystals is calculated by the plane wave expansion method.The transmission characteristics of the circulator are simulated by the finite element method.We perform the experiments in the microwave regime to validate the numerical results.At the central frequency of 10.15 GHz,the measured isolation and insertion loss of the circulator reaches-30.2 and-3.93 d B,respectively.The bandwidth of the circulator is about 550 MHz.The optimal experimental value of isolation is higher than the numerical value.展开更多
Established on October 18th of 2002, the School of Software Engineering of Beijing University of Posts and Telecommunications is one of the 35 national model schools of software engineering approved by the Ministry of...Established on October 18th of 2002, the School of Software Engineering of Beijing University of Posts and Telecommunications is one of the 35 national model schools of software engineering approved by the Ministry of Education and the National Committee of Development and Reform. According to current requirements and international trends, the school has set up its objective as to educate students with multi-level, practical, and composition talents. To this end, the school has established dynamic and flexible curriculums to train advanced software engineering professionals with sound overall capability and professional ethics, solid theoretical background, and extensive experiences.展开更多
文摘In recent years,the incidence rate of stroke has increased year by year.Post stroke depres‐sion is one of its main complications,which seriously affects the recovery of physiological functions and quality of life of stroke patients.Traditional Chinese medicine has signifi‐cant therapeutic effects in treating this disease.This article provides a classification and review of traditional Chinese medicine treatment methods for post-stroke depression,and looks forward to the current problems.
文摘Asphalt mow strips are typically used as vegetation barriers around guardrail posts in the design of roadside safety structures. Asphalt mow strips have historically been modeled as a rigid layer in simulations;this assumption results in significant ground level restraint on the guardrail post. However, experiments have shown that asphalt rupture should be considered in the analysis of the response of guardrail posts embedded in mow strips. The present study investigates the effect of asphalt material properties and mow strip geometry on guardrail post performance using finite element simulations. Numerical simulations are performed and correlated with results from static experiments and material testing. The test simulations and experimental results are used to evaluate the response of guardrail posts with various mow strip designs to predict the level of restraint from the asphalt layer. The model is then used to investigate the effects of asphalt material properties and mow strip geometry on the overall performance of the system. The results demonstrate that including asphalt rupture in numerical simulations is essential in accurately predicting the behavior of guardrail posts installed in asphalt mow strips. In addition, mow strip geometry along with asphalt material properties significantly affect the guardrail post response.
基金This work was supported in part by the National Natural Science Foundation of China under Grants 61602111,61502099,61502100,61532013the Jiangsu Provincial Natural Science Foundation of China under Grants BK20150628,BK20150637+2 种基金the Jiangsu Provincial Scientific and Technological Achievements Transfer Fund,and by the Jiangsu Provincial Key Laboratory of Network and Information Security under Grant BM2003201the Key Laboratory of Computer Network and Information Integration of Ministry of Education of China under Grant 93K-9Collaborative Innovation Center of Novel Software Technology and Industrialization.
文摘Sina Weibo,an online social network site,has gained popularity but lost it in recent years.Now we are still curious on the number of posts in Sina Weibo in its golden age.Besides checking this number in Sina’s operating results,we aim to estimate and verify this number through measurement by using statistical techniques.Existing approaches on measurement always rely on the supported streaming application programming interface(API)which provides proportional sampling.However no such API is available for Sina Weibo.Instead,Sina provides a public timeline API which provides non-proportional sampling but always returns a(nearly)fixed number of s amples.In this paper,we present a novel method utilizing this API and estimate the number of posts in Sina Weibo in its golden age.
文摘This paper aims to standardize health, safety and environment(HSE) training matrices for effectively identifying training requirements and enhancing job competency of grassroots posts in petroleum and petrochemical enterprises. After an investigation into HSE training performance in petroleum and petrochemical enterprises, HSE training matrices templates for 239 grassroots posts involving 22 primary petroleum and petrochemical disciplines were developed based on the technical requirements of HSE training matrices templates and the studies of template development processes and technical methods at grassroots level. Applications of these templates in 12 companies demonstrate their effectiveness in improving HSE training and management for grassroots posts,strengthening risk control and promoting the application of HSE system and tools in grassroots units.
文摘The research examines the way in which members of the U.S. House of Representative represent themselves on the social network site Facebook. Each member’s activity is observed on seven different occasions and the frequency and substantive character of posts made during the second half of 2013 are established. The focus is on position-taking posts versus posts which mention the district the member serves in. Our expectation is that members from electorally safe districts will be more likely to advertise their policy positions while members from marginal districts will be more inclined to advertise their district connections. We control for minority party status, gender, and ideological extremism among other concerns and learn electoral safety is a good predictor of both “position-taking” and “district mentions”. Consistent with an electoral motive, we also find members from the minority party less likely to take positions on the issues of the day and more likely to mention the district they serve in.
文摘In the last few decades, the impacts of human activities on ecosystem have rapidly increased resulting to detrimental ecosystem changes. Human-wildlife conflict (HWC) is one of the greatest consequences of human impacts on the environment. Although HWC has been there for decades, its intensity seems to be growing with the spread of human settlements, changes in land use patterns and diminishing suitable natural habitats for wildlife. To mitigate HWC, various strategies have been devised and implemented. This study focused on predator-proof bomas (PPBs) approach that is ongoing in Amboseli ecosystem. The aim was to establish reasons behind the slow adoptions of the recycled plastics poles by owners of PPBs that were constructed using wooden posts between the years 2010 to 2013. Randomly selected 36 PPB homestead owners were interviewed and the physical structures of their PPBs assessed. Results revealed a positive relationship between PPB size and number of poles damaged;and a significant association between the damaged posts and the number of indigenous posts replaced in the three group ranches (X2 = 34.9331, df = 2, p < 0.05). Most of the respondents (89%) cited posts and doors (72%) as the main parts that needed repairs. About 80% of the respondents would recommend the plastic posts for use in constructing new PPBs by other people. Most of the PPB beneficiaries whose PPBs were constructed in 2010-2013 have opted for an “easy” alternative source of posts from the sparsely distrusted trees around their homesteads. It is recommend that an open window period should be tried to entice the wooden post PPBs owners to adopt the recycled plastic posts. This may necessitate upgrading the existing old wooden bomas to a “smart PPBs”. It is suggested that the “smart PPBs” should not only have recycled plastic posts but also “free” energy saving stoves in each household to reduce the level of deforestation.
文摘This study aimed to evaluate the influence of quartz fiber post placement on the fracture resistance of endodontically treated premolars with different dental defects under dynamic loading.Fifty extracted single-rooted mandibular premolars were randomized into five groups.Each group was prepared according to numbers of residual walls ranged from 0 to 4.Then each group was divided into two subgroups with one restored with quartz fiber posts and the other without posts.In no-post groups,gutta percha point 2 mm below cemento-enamel junction was removed.Composite resin was adapted to the well and used to shape the core directly.Each tooth was restored with a complete metal crown.Dynamic loading was carried out in a masticatory simulator with a nominal load of 50 N at 2 Hz for 300 000 loading cycles.Then a quasi-statically load was applied in a universal testing machine 306 to the long axis with a crosshead speed of 1 mm?min21until fracture.Data were analyzed with one-way analysis of variance and pairwise comparison(P,0.05).No specimens failed during dynamic loading.The fracture resistance enhanced with the increase of numbers of coronal walls and the differences were significant(P,0.05).Placement of fiber posts had a significant effect when fewer than two walls remained(P,0.05),but it had no significant influence in groups with two,three or four walls(P.0.05).Fiber post did not change failure mode,and the fracture pattern was mainly favorable.More dentin walls need to be retained in clinic.When no less than two walls remained,a fiber post is not always necessary.
基金supported by a grant from a program of research and development of Hubei Province (No. 2008-BCC 001)
文摘The aim of this study is to investigate the influence of different posts on the fracture mechanics of endodontically-treated teeth with open apex. Forty-eight human maxillary anterior teeth were collected, and the root was transversely sectioned 12 mm under the cementoenamal junction (CEJ). These samples were then randomly divided into two groups, i.e., minor diameter open apex root (group A) and major diameter open apex root (group B), with mineral trioxide aggregate (MTA) placed into the apical 4 mm in the root canals. Subsequently, both groups were respectively further divided into three subgroups as follows: fiber-post (subgroup 1), metal post (subgroup 2) and non-post (subgroup 3) group. Teeth were restored with a composite resin crown and tested by using a universal testing machine at the rate of 1 mm/min cross-head. Values of the maximum fracture resistance and failure patterns were recorded and compared among all subgroups. In addition, the changes of MTA properties were carefully examined via X-ray photography. Our results indicate that (1) In group A, the mean value of fracture resistance for teeth restored with fiber posts were statistically higher than that with either metal post or non-post; (2) In group B, there was no statistically significant difference in the mean value of fracture resistance among three subgroups; (3) No statistical significance in the mean value of fracture resistance was found between group A and group B; (4) The failure modes of most samples (58%) were irreparable; (5) MTA in two teeth developed cracks after loading tests. In conclusion, endodontically-treated teeth restored with fiber posts are more resistant to fracture than those restored with either metal posts or non-post, and most of the fracture modes are catastrophic in nature.
文摘A cradle-to-grave life cycle assessment is done to identify the environmental impacts of chromated copper arsenate (CCA)-treated timber used for highway guard rail posts, to understand the processes that contribute to the total impacts, and to determine how the impacts compare to the primary alternative product, galvanized steel posts. Guard rail posts are the supporting structures for highway guard rails. Transportation engineers, as well as public and regulatory interests, have increasing need to understand the environmental implications of guard rail post selection, in addition to factors such as costs and service performance. This study uses a life cycle inventory (LCI) to catalogue the input and output data from guard rail post manufacture, service life, and disposition, and a life cycle impact assessment (LCIA) to assess anthropogenic and net greenhouse gas (GHG), acidification, smog, ecotoxicity, and eutrophication potentially resulting from life cycle air emissions. Other indicators of interest also are tracked, such as fossil fuel and water use. Comparisons of guard rail post products are made at a functional unit of one post per year of service. This life cycle assessment (LCA) finds that the manufacture, use, and disposition of CCA-treated wood guard rails offers lower fossil fuel use and lower anthropogenic and net GHG emissions, acidification, smog potential, and ecotoxicity environmental impacts than impact indicator values for galvanized steel posts. Water use and eutrophication impact indicator values for CCA-treated guard rail posts are greater than impact indicator values for galvanized steel guard rail posts.
基金Funded by the National Natural Science Foundation of China(No.H1408)
文摘The effects of different post-space pretreatments on the retentive force of fiber posts cemented with a self-adhesive resin cement were investigated. Twenty-eight single-canal premolars were obturated by Resilon using warm vertical compaction and treated with distilled water, 2.5% NaOCl, 17% EDTA and 2.5% NaOCI; or 17% EDTA, 2.5% NaOCI, and ultrasonic agitation (U/E/N treatment). Subsequently, radicular dentin surfaces were observed under scanning electron microscopy (SEM). RelyX Fiber Posts were cemented in the treated canals by using RelyX U100, and thin-slice push-out test and SEM observation of coronal and apical regions of the specimens were performed. Data were analyzed using two-way ANOVA and Tukey's HSD post- hoc tests, and the percentage of failure type was calculated. Ultrasonic/EDTA/NaOC1 irrigation showed the maximum effectiveness in removing the smear layer and debris on the dentin surface. The apical bond strength of the experimental groups was significantly higher than that of the control group (P〈 0.05). Adhesive failure between cement and dentin was the most common mode of failure. No obvious RDIZ or resin tag was detected. Chemical irrigants facilitated the bonding of these fiber posts, and ultrasonic activation improved retention. Future studies should evaluate the effectiveness of irrigation on fiber post push-out strength in fatigue cycling condition.
文摘For years,non-structural masonry walls have received little attention by code developers and professional engineers.Recently,significant efforts have been made to shed more light on out-of-plane(OOP)behavior of non-structural masonry walls.In updated provisions of the Iranian seismic code,bed joint reinforcements(BJRs)and steel wallposts have been suggested for use.BJRs are horizontal reinforcements;steel wallposts are vertical truss-like elements intended to provide additional OOP restraints for a wall.The contribution of BJRs has previously been investigated by the authors.This study is devoted to investigating the contribution of steel wallposts to the OOP behavior of non-structural masonry walls.Using pre-validated 3D finite element(FE)models,the OOP behavior of 180 non-structural masonry walls with varying configurations and details are investigated.The OOP pressure-displacement curve,ultimate strength,the response modification factor,and the cracking pattern are among the results presented in this study.It is found that steel wallposts,especially those with higher rigidity,can improve the OOP strength of the walls.The contribution of wallposts in the case of shorter length walls and walls with an opening are more pronounced.Results also indicate that masonry walls with wallpost generally have smaller modification factors compared to similar walls without wallpost.
文摘Using the rigid visco-plastic Finite Element Method (FEM), the process offorging for long cone-shaped posts made of aluminum alloys was modeled and the correspondingdistributions of the field variables were obtained based on considering aberrance of grids, dynamicboundary conditions, non-stable process, coupled thermo-mechanical behavior and other specialproblems. The difficulties in equipment selection and die analysis caused by the long cone shape ofpost, as well as by pressure calculation were solved.
基金supported by the National Natural Science Foundation of China under Grant No.61171006
文摘A novel H-plane cross-shaped circulator based on magneto-photonic crystals is experimentally investigated.The band gap of the TE mode for the photonic crystals is calculated by the plane wave expansion method.The transmission characteristics of the circulator are simulated by the finite element method.We perform the experiments in the microwave regime to validate the numerical results.At the central frequency of 10.15 GHz,the measured isolation and insertion loss of the circulator reaches-30.2 and-3.93 d B,respectively.The bandwidth of the circulator is about 550 MHz.The optimal experimental value of isolation is higher than the numerical value.
文摘Established on October 18th of 2002, the School of Software Engineering of Beijing University of Posts and Telecommunications is one of the 35 national model schools of software engineering approved by the Ministry of Education and the National Committee of Development and Reform. According to current requirements and international trends, the school has set up its objective as to educate students with multi-level, practical, and composition talents. To this end, the school has established dynamic and flexible curriculums to train advanced software engineering professionals with sound overall capability and professional ethics, solid theoretical background, and extensive experiences.