With the rapid growth of the number and flight time of unmanned aerial vehicles(UAVs),safety accidents caused by UAVs flight risk is increasing gradually.Safe air route planning is an effective means to reduce the ope...With the rapid growth of the number and flight time of unmanned aerial vehicles(UAVs),safety accidents caused by UAVs flight risk is increasing gradually.Safe air route planning is an effective means to reduce the operational risk of UAVs at the strategic level.The optimal air route planning model based on ground risk assessment is presented by considering the safety cost of UAV air route.Through the rasterization of the ground surface under the air route,the safety factor of each grid is defined with the probability of fatality on the ground per flight hour as the quantitative index.The air route safety cost function is constructed based on the safety factor of each grid.Then,the total cost function considering both air route safety and flight distance is established.The expected function of the ant colony algorithm is rebuilt and used as the algorithm to plan the air routes.The effectiveness of the new air route planning model is verified through the logistical distribution scenario on urban airspace.The results indicate that the new air route planning model considering safety factor can greatly improve the overall safety of air route under small increase of the total flight time.展开更多
This study aimed to examine some coursebooks of English as a Foreign Language （EFL） to see whether they involve any cross-cultural topics belonging to different cultures from different countries in the world. Assumi...This study aimed to examine some coursebooks of English as a Foreign Language （EFL） to see whether they involve any cross-cultural topics belonging to different cultures from different countries in the world. Assuming that EFL coursebooks written after the communicative movements in foreign language teaching and learning in the 1970s and the 1980s would have a plenty of cross-cultural elements, it was expected to see these coursebooks would also have a lot of cross-cultural elements, especially regarding their publication dates. This study aimed to investigate to what extent teaching materials used in EFL setting involve intercultural elements. Accordingly, 5 coursebooks were evaluated, and topics and number of cross-cultural elements were presented. The coursebooks used in the study were published in 1998, 1999, 1999, 2001 and 2006 namely. However, as the results displayed, the frequency of cross-cultural elements were not mutually related to their publication dates. The distribution and frequency of cross-cultural elements were not balanced with the dates chronologically.展开更多
The research study proposes to examine a three-dimensional visualization program, emphasizing on improving genetic algorithms through the optimization of a layout design-based standard and discrete shipbuilding worksh...The research study proposes to examine a three-dimensional visualization program, emphasizing on improving genetic algorithms through the optimization of a layout design-based standard and discrete shipbuilding workshop. By utilizing a steel processing workshop as an example, the principle of minimum logistic costs will be implemented to obtain an ideological equipment layout, and a mathematical model. The objectiveness is to minimize the total necessary distance traveled between machines. An improved control operator is implemented to improve the iterative efficiency of the genetic algorithm, and yield relevant parameters. The Computer Aided Tri-Dimensional Interface Application （CATIA） software is applied to establish the manufacturing resource base and parametric model of the steel processing workshop. Based on the results of optimized planar logistics, a visual parametric model of the steel processing workshop is constructed, and qualitative and quantitative adjustments then are applied to the model. The method for evaluating the results of the layout is subsequently established through the utilization of AHP. In order to provide a mode of reference to the optimization and layout of the digitalized production workshop, the optimized discrete production workshop will possess a certain level of practical significance.展开更多
The reinforcement effect of a reconstruction scheme for a steel factory building was investigated using finite element method and dynamic performance test. The workshop concerned is a portal frame structure with four ...The reinforcement effect of a reconstruction scheme for a steel factory building was investigated using finite element method and dynamic performance test. The workshop concerned is a portal frame structure with four spans and two slope roofs, of which ten columns need cutting for expanding span. The design and reconstruction project of column-cut supported by joist were introduced, which includes column reinforcement, connection rebuilding between brackets and crane beams, and the changing of rigid joint into hinge joint. The construction scheme was put forward in the light of the characteristics of the reinforcement and reconstruction. Spot test of dynamic performance on the workshop and comparison with theoretical analysis results show that the column-cut supported by joist design is effective and the reconstruction project is successful.展开更多
Equivalent ways commonly used in engineering works are not effective to estimate the reliability of tandem system based on L-M method. One modified L-M method is an important means to estimate the reliability of CNC l...Equivalent ways commonly used in engineering works are not effective to estimate the reliability of tandem system based on L-M method. One modified L-M method is an important means to estimate the reliability of CNC lathes. A method of using two named confidence limits for the estimation is put forward. Fitting resuits of the sub-systems of CNC machine tools are estimated. And the scattered level of confidence limits facing the reliability matrix of sub-systems can be clearly seen.展开更多
The traditional method of assessing students' writing puts too much emphasis on the grammatical errors, which often frustrates and bores student writers. In view of this situation, this paper, employing systemic f...The traditional method of assessing students' writing puts too much emphasis on the grammatical errors, which often frustrates and bores student writers. In view of this situation, this paper, employing systemic functional approach, puts forward a new perspective on assessing writing — a textual metafunction perspective, by analyzing the Thematic structure both above and at the clausal level and uncovering the strengths and weaknesses of the student's writing, and giving it a full functional analysis from the three metafuncitons. In the end, the paper points out the pedagogical implications of this method in English writing assessing and teaching.展开更多
Objective： To investigate the clinical outcome of modified Blair ankle fusion for ankle arthritis. Methods： Between November 2009 and June 2012, 28 patients with ankle arthritis were treated, among whom 11 had obvio...Objective： To investigate the clinical outcome of modified Blair ankle fusion for ankle arthritis. Methods： Between November 2009 and June 2012, 28 patients with ankle arthritis were treated, among whom 11 had obvious foot varus deformity, and 17 were almost normal in appearance. There were 13 males and 15 females with an average age of 49.4 years （range, 23-67 years）. The main symptoms included swelling, pain, and a limited range of motion of the ankles. The ankle joints functions were assessed by American Orthopedic Foot and Ankle Society （AOFAS） ankle and hindfoot score and visual analog scale （VAS） preoperatively and at I year follow-up. Results： Twenty-eight patients were followed up for 19.8 months on average （range, 1-2 years）. Superficial wound infection occurred in 3 cases, and was cured after debridement; the other incisions healed by first intention without complications. All ankles were fused at 1 year follow-up after operation. The symptom was relieved completely in all patients at last follow-up without complication of implant failure, or nonunion. The postoperative AOFAS ankle and hindfoot score was 83.13±3.76, showing significant difference when compared with the preoperative score （45.38±3.21, P〈0.01）. VAS was significantly decreased from 8.01±0.63 to 2.31±1.05 at 1 year follow-up （P〈0.05）. Conclusion： Modified Blair ankle fusion has the advantages of high feasiblity, less cost and rigid fixation. It shows high reliability in pain relief and may obtain a good clinical effectiveness.展开更多
基金This work is supported by the Scientific Research Project of Tianjin Education Commission(No.2019KJ128).
文摘With the rapid growth of the number and flight time of unmanned aerial vehicles(UAVs),safety accidents caused by UAVs flight risk is increasing gradually.Safe air route planning is an effective means to reduce the operational risk of UAVs at the strategic level.The optimal air route planning model based on ground risk assessment is presented by considering the safety cost of UAV air route.Through the rasterization of the ground surface under the air route,the safety factor of each grid is defined with the probability of fatality on the ground per flight hour as the quantitative index.The air route safety cost function is constructed based on the safety factor of each grid.Then,the total cost function considering both air route safety and flight distance is established.The expected function of the ant colony algorithm is rebuilt and used as the algorithm to plan the air routes.The effectiveness of the new air route planning model is verified through the logistical distribution scenario on urban airspace.The results indicate that the new air route planning model considering safety factor can greatly improve the overall safety of air route under small increase of the total flight time.
文摘This study aimed to examine some coursebooks of English as a Foreign Language （EFL） to see whether they involve any cross-cultural topics belonging to different cultures from different countries in the world. Assuming that EFL coursebooks written after the communicative movements in foreign language teaching and learning in the 1970s and the 1980s would have a plenty of cross-cultural elements, it was expected to see these coursebooks would also have a lot of cross-cultural elements, especially regarding their publication dates. This study aimed to investigate to what extent teaching materials used in EFL setting involve intercultural elements. Accordingly, 5 coursebooks were evaluated, and topics and number of cross-cultural elements were presented. The coursebooks used in the study were published in 1998, 1999, 1999, 2001 and 2006 namely. However, as the results displayed, the frequency of cross-cultural elements were not mutually related to their publication dates. The distribution and frequency of cross-cultural elements were not balanced with the dates chronologically.
文摘The research study proposes to examine a three-dimensional visualization program, emphasizing on improving genetic algorithms through the optimization of a layout design-based standard and discrete shipbuilding workshop. By utilizing a steel processing workshop as an example, the principle of minimum logistic costs will be implemented to obtain an ideological equipment layout, and a mathematical model. The objectiveness is to minimize the total necessary distance traveled between machines. An improved control operator is implemented to improve the iterative efficiency of the genetic algorithm, and yield relevant parameters. The Computer Aided Tri-Dimensional Interface Application （CATIA） software is applied to establish the manufacturing resource base and parametric model of the steel processing workshop. Based on the results of optimized planar logistics, a visual parametric model of the steel processing workshop is constructed, and qualitative and quantitative adjustments then are applied to the model. The method for evaluating the results of the layout is subsequently established through the utilization of AHP. In order to provide a mode of reference to the optimization and layout of the digitalized production workshop, the optimized discrete production workshop will possess a certain level of practical significance.
基金Supported by Program for New Century Excellent Talents in University (No. NCET-06-0228)
文摘The reinforcement effect of a reconstruction scheme for a steel factory building was investigated using finite element method and dynamic performance test. The workshop concerned is a portal frame structure with four spans and two slope roofs, of which ten columns need cutting for expanding span. The design and reconstruction project of column-cut supported by joist were introduced, which includes column reinforcement, connection rebuilding between brackets and crane beams, and the changing of rigid joint into hinge joint. The construction scheme was put forward in the light of the characteristics of the reinforcement and reconstruction. Spot test of dynamic performance on the workshop and comparison with theoretical analysis results show that the column-cut supported by joist design is effective and the reconstruction project is successful.
基金Sponsored by the National Natural Science Foundation of China(Grant No.40774048)
文摘Equivalent ways commonly used in engineering works are not effective to estimate the reliability of tandem system based on L-M method. One modified L-M method is an important means to estimate the reliability of CNC lathes. A method of using two named confidence limits for the estimation is put forward. Fitting resuits of the sub-systems of CNC machine tools are estimated. And the scattered level of confidence limits facing the reliability matrix of sub-systems can be clearly seen.
文摘The traditional method of assessing students' writing puts too much emphasis on the grammatical errors, which often frustrates and bores student writers. In view of this situation, this paper, employing systemic functional approach, puts forward a new perspective on assessing writing — a textual metafunction perspective, by analyzing the Thematic structure both above and at the clausal level and uncovering the strengths and weaknesses of the student's writing, and giving it a full functional analysis from the three metafuncitons. In the end, the paper points out the pedagogical implications of this method in English writing assessing and teaching.
文摘Objective： To investigate the clinical outcome of modified Blair ankle fusion for ankle arthritis. Methods： Between November 2009 and June 2012, 28 patients with ankle arthritis were treated, among whom 11 had obvious foot varus deformity, and 17 were almost normal in appearance. There were 13 males and 15 females with an average age of 49.4 years （range, 23-67 years）. The main symptoms included swelling, pain, and a limited range of motion of the ankles. The ankle joints functions were assessed by American Orthopedic Foot and Ankle Society （AOFAS） ankle and hindfoot score and visual analog scale （VAS） preoperatively and at I year follow-up. Results： Twenty-eight patients were followed up for 19.8 months on average （range, 1-2 years）. Superficial wound infection occurred in 3 cases, and was cured after debridement; the other incisions healed by first intention without complications. All ankles were fused at 1 year follow-up after operation. The symptom was relieved completely in all patients at last follow-up without complication of implant failure, or nonunion. The postoperative AOFAS ankle and hindfoot score was 83.13±3.76, showing significant difference when compared with the preoperative score （45.38±3.21, P〈0.01）. VAS was significantly decreased from 8.01±0.63 to 2.31±1.05 at 1 year follow-up （P〈0.05）. Conclusion： Modified Blair ankle fusion has the advantages of high feasiblity, less cost and rigid fixation. It shows high reliability in pain relief and may obtain a good clinical effectiveness.
