In order to increase the accuracy of microscopic traffic flow simulation,two acceleration models are presented to simulate car-following behaviors of the lane-changing vehicle and following putative vehicle during the...In order to increase the accuracy of microscopic traffic flow simulation,two acceleration models are presented to simulate car-following behaviors of the lane-changing vehicle and following putative vehicle during the discretionary lanechanging preparation( DLCP) process, respectively. The proposed acceleration models can reflect vehicle interaction characteristics. Samples used for describing the starting point and the ending point of DLCP are extracted from a real NGSIM vehicle trajectory data set. The acceleration model for a lanechanging vehicle is supposed to be a linear acceleration model.The acceleration model for the following putative vehicle is constructed by referring to the optimal velocity model,in which optimal velocity is defined as a linear function of the velocity of putative leading vehicle. Similar calibration,a hypothesis test and parameter sensitivity analysis were conducted on the acceleration model of the lane-changing vehicle and following putative vehicle,respectively. The validation results of the two proposed models suggest that the training and testing errors are acceptable compared with similar works on calibrations for car following models. The parameter sensitivity analysis shows that the subtle observed error does not lead to severe variations of car-following behaviors of the lane-changing vehicle and following putative vehicle.展开更多
To investigated characteristics, diagnosis, bowel-cleansing preparation, sedation, and colonoscope length and diameter in Japanese pediatric patients receiving total colonoscopy. METHODSThe present study evaluated con...To investigated characteristics, diagnosis, bowel-cleansing preparation, sedation, and colonoscope length and diameter in Japanese pediatric patients receiving total colonoscopy. METHODSThe present study evaluated consecutive patients aged ≤ 15 years who had undergone their first colonoscopy in Kurume University between January 2007 and February 2015. Data were retrospectively analyzed. We identified 110 pediatric patients who had undergone colonoscopy that had reached the cecum, allowing the observation of the total colon. RESULTSHematochezia, abdominal pain, and diarrhea were the most common symptoms. For bowel-cleansing preparation, pediatric patients aged ≤ 12 years were treated with magnesium citrate, and patients aged 13-15 years were treated with polyethylene glycol 4000. For sedation, thiamylal with pentazocine, which has an analgesic effect, was used in patients aged ≤ 6 years, and midazolam with pentazocine was used in patients aged ≥ 7 years. Regarding the choice of endoscope, short and thin endoscopes were selected for younger patients, particularly patients aged ≤ 3 years. Positive diagnoses were made in 78 patients (70.9%). Inflammatory bowel disease (n = 49, 44.5%), including ulcerative colitis (n = 37, 33.6%) and Crohn’s disease (n = 12, 10.9%), was the most common diagnosis. CONCLUSIONColonoscopy offers a high diagnostic capability for pediatric patients with gastrointestinal symptoms. The selection of appropriate management the performance of colonoscopy is important in pediatric patients.展开更多
Potassium promoted iron–zinc catalysts prepared by co-precipitation method(C–Fe–Zn/K),solvothermal method(S–Fe–Zn/K)and hydrothermal method(H–Fe–Zn/K)could selectively convert CO_2to light olefins,respectively....Potassium promoted iron–zinc catalysts prepared by co-precipitation method(C–Fe–Zn/K),solvothermal method(S–Fe–Zn/K)and hydrothermal method(H–Fe–Zn/K)could selectively convert CO_2to light olefins,respectively.The physicochemical properties of the obtained catalysts were determined by SEM,N_2physisorption,XRD,H_2-TPR,CO_2-TPD and XPS measurements.The results demonstrated that preparation methods had great influences on the morphology,phase structures,reduction and adsorption behavior,and hence the catalytic performance of the catalysts.The samples prepared by hydrothermal and co-precipitation method generated small uniform particles and led to lower specific surface area.In contrast,microspheres with larger specific surface area were formed by self-assembly of nanosheets using solvothermal method.ZnFe_2O_4was the only detectable phase in the fresh C–2Fe–1Zn/K,S–3Fe–1Zn/K and S–2Fe–1Zn/K samples.ZnFe_2O_4and ZnO co-existed with increasing Zncontent in S–1Fe–1Zn/K sample,while ZnO and Fe_2O_3could be observed over H–2Fe–1Zn/K sample.All the used samples contained Fe_3O_4,ZnO and Fe_5C_2.The peak intensity of ZnO was strong in the AR-H–2Fe–1Zn/K sample while it was the lowest in the AR-C–2Fe–1Zn/K sample after reaction.The formation of ZnFe_2O_4increased the interaction between iron and zinc for C–2Fe–1Zn/K and S–Fe–Zn/K samples,causing easier reduction of Fe_2O_3to Fe_3O_4.The surface basicity of the sample prepared by co-precipitation method was much more than that of the other two methods.During CO_2hydrogenation,all the catalysts showed good activity and olefin selectivity.The CO selectivity was increased with increasing Zncontent over S–Fe–Zn/K samples.H–2Fe–1Zn/K catalyst preferred to the production of C_5^+hydrocarbons.CO_2conversion of 54.76%and C_2~=–C_4~=contents of 57.38%were obtained on C–2Fe–1Zn/K sample,respectively.展开更多
To protect carbon/carbon (C/C) composites from oxidation, a SiC coating modified with SiO2 was prepared by a complex technology. The inner SiC coating with thickness varying from 150 to 300 μm was initially coated by...To protect carbon/carbon (C/C) composites from oxidation, a SiC coating modified with SiO2 was prepared by a complex technology. The inner SiC coating with thickness varying from 150 to 300 μm was initially coated by chemical vapor reaction (CVR): a simple and cheap technique to prepare the SiC coating via siliconizing the substrate that was exposed to the mixed vapor (Si and SiO2) at high temperatures (1 923?2 273 K). Then the as-prepared coating was processed by a dipping and drying procedure with tetraethoxysilane as source materials to form SiO2 to fill the cracks and holes. Oxidation tests show that, after oxidation in air at 1 623 K for 10 h and thermal cycling between 1 623 K and room temperature 5 times, the mass loss of the CVR coated sample is up to 18.21%, while the sample coated with modified coating is only 5.96%, exhibiting an obvious improvement of oxidation and thermal shock resistance of the coating. The mass loss of the modified sample is mainly contributed to the reaction of C/C substrate with oxygen diffusing through the penetrating cracks formed in thermal shock tests.展开更多
This study aims at assessing whether a significant within-year seasonality exists in the loan loss provisioning behavior of European listed banks observed in the period from 2004 to 2013. Since the accuracy of auditin...This study aims at assessing whether a significant within-year seasonality exists in the loan loss provisioning behavior of European listed banks observed in the period from 2004 to 2013. Since the accuracy of auditing processes and the level of disclosure requirements in financial reports differ among quarters, during the year, banks may have a leeway to underestimate and postpone the complete provisioning of loan losses in the less regulated and less audited quarters. We hypothesize that those differences are relevant factors which determine non-lower or significantly higher average levels of loan loss provisions in the half-yearly and especially in the annual financial reports than in the interim management statements disclosed in the first and the third quarters of the year. We also investigate the impact of the recent financial crisis and develop a special analysis for the ltalian banks＇ case. The empirical results support our hypotheses, suggesting that, in some cases, a convergence among quarterly levels of auditing processes and disclosure requirements may be needed. Our work contributes to the existing literature by providing additional evidences and considerations on the within-year seasonality in the loan loss provisioning behavior of European listed banks observed in the last decade.展开更多
Planning, as a task condition, is hypothesized to influence L2 test performance and thus test scores（Skehan, 1998）. This study investigates the effects of lengths of strategic planning time on L2 paired oral test pe...Planning, as a task condition, is hypothesized to influence L2 test performance and thus test scores（Skehan, 1998）. This study investigates the effects of lengths of strategic planning time on L2 paired oral test performance, moderated by L2 proficiency. It aims to determine whether differences in performance result from 0, 1, 2 or 3 minutes of planning time, and whether planning time and proficiency interactively affect performance. The participants were 72 Chinese EFL learners, divided into four groups, each performing the same dialogic task with 1 or 2 or 3 minute planning time or none. All speech recordings were rated by two trained raters, and the transcripts of the speech samples subjected to a discourse analysis, measuring fluency features of Rate A and Rate B, complexity features of syntactic complexity, syntactic variety and lexical variety, and accuracy features of error-free clauses and correct verb forms. Findings show a stable accuracy, higher fluency in the planned condition, and greater syntactic complexity when learners are given 3 minutes＇ planning time. No interaction is found between planning time and proficiency.展开更多
基金The National Basic Research Program of China(No.2012CB725405)the National Natural Science Foundation of China(No.51308115)+1 种基金the Science and Technology Demonstration Project of Ministry of Transport of China(No.2015364X16030)Fundamental Research Funds for the Central Universities,the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYLX15_0153)
文摘In order to increase the accuracy of microscopic traffic flow simulation,two acceleration models are presented to simulate car-following behaviors of the lane-changing vehicle and following putative vehicle during the discretionary lanechanging preparation( DLCP) process, respectively. The proposed acceleration models can reflect vehicle interaction characteristics. Samples used for describing the starting point and the ending point of DLCP are extracted from a real NGSIM vehicle trajectory data set. The acceleration model for a lanechanging vehicle is supposed to be a linear acceleration model.The acceleration model for the following putative vehicle is constructed by referring to the optimal velocity model,in which optimal velocity is defined as a linear function of the velocity of putative leading vehicle. Similar calibration,a hypothesis test and parameter sensitivity analysis were conducted on the acceleration model of the lane-changing vehicle and following putative vehicle,respectively. The validation results of the two proposed models suggest that the training and testing errors are acceptable compared with similar works on calibrations for car following models. The parameter sensitivity analysis shows that the subtle observed error does not lead to severe variations of car-following behaviors of the lane-changing vehicle and following putative vehicle.
文摘To investigated characteristics, diagnosis, bowel-cleansing preparation, sedation, and colonoscope length and diameter in Japanese pediatric patients receiving total colonoscopy. METHODSThe present study evaluated consecutive patients aged ≤ 15 years who had undergone their first colonoscopy in Kurume University between January 2007 and February 2015. Data were retrospectively analyzed. We identified 110 pediatric patients who had undergone colonoscopy that had reached the cecum, allowing the observation of the total colon. RESULTSHematochezia, abdominal pain, and diarrhea were the most common symptoms. For bowel-cleansing preparation, pediatric patients aged ≤ 12 years were treated with magnesium citrate, and patients aged 13-15 years were treated with polyethylene glycol 4000. For sedation, thiamylal with pentazocine, which has an analgesic effect, was used in patients aged ≤ 6 years, and midazolam with pentazocine was used in patients aged ≥ 7 years. Regarding the choice of endoscope, short and thin endoscopes were selected for younger patients, particularly patients aged ≤ 3 years. Positive diagnoses were made in 78 patients (70.9%). Inflammatory bowel disease (n = 49, 44.5%), including ulcerative colitis (n = 37, 33.6%) and Crohn’s disease (n = 12, 10.9%), was the most common diagnosis. CONCLUSIONColonoscopy offers a high diagnostic capability for pediatric patients with gastrointestinal symptoms. The selection of appropriate management the performance of colonoscopy is important in pediatric patients.
基金Supports by the National Natural Science Foundation of China(21666030,21366025)National First-rate Discipline Construction Project of Ningxia(NXYLXK2017A04)
文摘Potassium promoted iron–zinc catalysts prepared by co-precipitation method(C–Fe–Zn/K),solvothermal method(S–Fe–Zn/K)and hydrothermal method(H–Fe–Zn/K)could selectively convert CO_2to light olefins,respectively.The physicochemical properties of the obtained catalysts were determined by SEM,N_2physisorption,XRD,H_2-TPR,CO_2-TPD and XPS measurements.The results demonstrated that preparation methods had great influences on the morphology,phase structures,reduction and adsorption behavior,and hence the catalytic performance of the catalysts.The samples prepared by hydrothermal and co-precipitation method generated small uniform particles and led to lower specific surface area.In contrast,microspheres with larger specific surface area were formed by self-assembly of nanosheets using solvothermal method.ZnFe_2O_4was the only detectable phase in the fresh C–2Fe–1Zn/K,S–3Fe–1Zn/K and S–2Fe–1Zn/K samples.ZnFe_2O_4and ZnO co-existed with increasing Zncontent in S–1Fe–1Zn/K sample,while ZnO and Fe_2O_3could be observed over H–2Fe–1Zn/K sample.All the used samples contained Fe_3O_4,ZnO and Fe_5C_2.The peak intensity of ZnO was strong in the AR-H–2Fe–1Zn/K sample while it was the lowest in the AR-C–2Fe–1Zn/K sample after reaction.The formation of ZnFe_2O_4increased the interaction between iron and zinc for C–2Fe–1Zn/K and S–Fe–Zn/K samples,causing easier reduction of Fe_2O_3to Fe_3O_4.The surface basicity of the sample prepared by co-precipitation method was much more than that of the other two methods.During CO_2hydrogenation,all the catalysts showed good activity and olefin selectivity.The CO selectivity was increased with increasing Zncontent over S–Fe–Zn/K samples.H–2Fe–1Zn/K catalyst preferred to the production of C_5^+hydrocarbons.CO_2conversion of 54.76%and C_2~=–C_4~=contents of 57.38%were obtained on C–2Fe–1Zn/K sample,respectively.
基金Project(2006CB600901) supported by the National Basic Research Program of ChinaProject(50802115) supported by the National Natural Science Foundation of China
文摘To protect carbon/carbon (C/C) composites from oxidation, a SiC coating modified with SiO2 was prepared by a complex technology. The inner SiC coating with thickness varying from 150 to 300 μm was initially coated by chemical vapor reaction (CVR): a simple and cheap technique to prepare the SiC coating via siliconizing the substrate that was exposed to the mixed vapor (Si and SiO2) at high temperatures (1 923?2 273 K). Then the as-prepared coating was processed by a dipping and drying procedure with tetraethoxysilane as source materials to form SiO2 to fill the cracks and holes. Oxidation tests show that, after oxidation in air at 1 623 K for 10 h and thermal cycling between 1 623 K and room temperature 5 times, the mass loss of the CVR coated sample is up to 18.21%, while the sample coated with modified coating is only 5.96%, exhibiting an obvious improvement of oxidation and thermal shock resistance of the coating. The mass loss of the modified sample is mainly contributed to the reaction of C/C substrate with oxygen diffusing through the penetrating cracks formed in thermal shock tests.
文摘This study aims at assessing whether a significant within-year seasonality exists in the loan loss provisioning behavior of European listed banks observed in the period from 2004 to 2013. Since the accuracy of auditing processes and the level of disclosure requirements in financial reports differ among quarters, during the year, banks may have a leeway to underestimate and postpone the complete provisioning of loan losses in the less regulated and less audited quarters. We hypothesize that those differences are relevant factors which determine non-lower or significantly higher average levels of loan loss provisions in the half-yearly and especially in the annual financial reports than in the interim management statements disclosed in the first and the third quarters of the year. We also investigate the impact of the recent financial crisis and develop a special analysis for the ltalian banks＇ case. The empirical results support our hypotheses, suggesting that, in some cases, a convergence among quarterly levels of auditing processes and disclosure requirements may be needed. Our work contributes to the existing literature by providing additional evidences and considerations on the within-year seasonality in the loan loss provisioning behavior of European listed banks observed in the last decade.
基金part of a project funded by Humanities and Social Science Research Foundation of the Ministry of Education of China,project No:12YJC740101
文摘Planning, as a task condition, is hypothesized to influence L2 test performance and thus test scores（Skehan, 1998）. This study investigates the effects of lengths of strategic planning time on L2 paired oral test performance, moderated by L2 proficiency. It aims to determine whether differences in performance result from 0, 1, 2 or 3 minutes of planning time, and whether planning time and proficiency interactively affect performance. The participants were 72 Chinese EFL learners, divided into four groups, each performing the same dialogic task with 1 or 2 or 3 minute planning time or none. All speech recordings were rated by two trained raters, and the transcripts of the speech samples subjected to a discourse analysis, measuring fluency features of Rate A and Rate B, complexity features of syntactic complexity, syntactic variety and lexical variety, and accuracy features of error-free clauses and correct verb forms. Findings show a stable accuracy, higher fluency in the planned condition, and greater syntactic complexity when learners are given 3 minutes＇ planning time. No interaction is found between planning time and proficiency.
