To investigate the abnormal ground pressures and roof control problem in fully mechanized repeated mining of residual coal after room and pillar mining, the roof fracture structural model and mechanical model were dev...To investigate the abnormal ground pressures and roof control problem in fully mechanized repeated mining of residual coal after room and pillar mining, the roof fracture structural model and mechanical model were developed using numerical simulation and theoretical analysis. The roof fracture characteristics of a repeated mining face were revealed and the ground pressure law and roof supporting condi- tions of the repeated mining face were obtained. The results indicate that when the repeated mining face passes the residual pillars, the sudden instability causes fracturing in the main roof above the old goal and forms an extra-large rock block above the mining face. A relatively stable ＂Voussoir beam＂ structure is formed after the advance fracturing of the main roof. When the repeated mining face passes the old goaf, as the large rock block revolves and touches gangue, the rock block will break secondarily under overburden rock loads. An example calculation was performed involving an integrated mine in Shanxi province, results showed that minimum working resistance values of support determined to be reason- able were respectively 11,412 kN and 10,743 kN when repeated mining face passed through residual pillar and goaf. On-site ground pressure monitoring results indicated that the mechanical model and support resistance calculation were reasonable.展开更多
BACKGROUND Primary vaginal cancer is rare and most vaginal tumors are metastatic,often arising from adjacent gynecologic structures.Primary vaginal cancers are also more common among postmenopausal women and most of t...BACKGROUND Primary vaginal cancer is rare and most vaginal tumors are metastatic,often arising from adjacent gynecologic structures.Primary vaginal cancers are also more common among postmenopausal women and most of these are squamous cell carcinomas,with adenocarcinomas being relatively rare.Vaginal bleeding is the most common clinical manifestation of vaginal adenocarcinoma.About 70%of vaginal adenocarcinomas are stage I lesions at the time of diagnosis,for which radical surgery is recommended.However,more advanced vaginal cancers are not amenable to radical surgical treatment and have poor clinical outcomes.Optimal treatments modes are still being explored.Here,we report a rare case of stage IIb primary vaginal adenocarcinoma for which an individually designed vaginal applicator for after-loading radiotherapy was used to achieve good tumor control.CASE SUMMARY A 62-year-old woman presented to our clinic after 3 months of abnormal postmenopausal vaginal bleeding.Gynecological examination,computed tomography(CT),and positron emission tomography-CT showed a large mass(about 5 cm)on the anterior vaginal wall.Colposcopy biopsy confirmed adenocarcinoma of vaginal origin.After three cycles of carboplatin plus paclitaxel chemotherapy,the lesion partially shrunk.The patient then received external irradiation of 45 gray(gy)in 25 fractions,which further reduced the vaginal lesion,followed by after-loading radiotherapy of 30 gy in 5 fractions with an individually designed vaginal applicator.Three months later,magnetic resonance imaging showed a slight thickening CONCLUSION Primary vaginal adenocarcinoma is rare,and prognosis is poor in most vaginal cancers of locally advanced stages,which cannot be treated with radical surgery.Better tumor control can be achieved with an individualized vaginal applicator that allows administration of a higher radical dose to the tumor area while protecting normal tissues.展开更多
Updates to traffic signal timing plans are expected to either improve operations or mitigate the effects of increased volumes. Longitudinal before-after studies are important when validating changes to traffic signal ...Updates to traffic signal timing plans are expected to either improve operations or mitigate the effects of increased volumes. Longitudinal before-after studies are important when validating changes to traffic signal systems, but they have historically required field data collection as well as deployment of extensive detection and communication equipment. These infrastructure-based techniques are costly and hard to scale. This study utilizes commercially available connected vehicle (CV) trajectory data to assess the change in performance between August 2020 and August 2021 on a 22-intersection corridor associated with the implementation of a semi-automated adaptive control system. Approximately 1 million trajectories and 13.5 million GPS points are analyzed for weekdays in August 2020 and August 2021. The vehicle trajectory data is used to compute corridor travel times and linear referenced relative to the far side of each intersection to generate Purdue Probe Diagrams (PPD). Using the PPDs, operational measurements such as arrivals on green (AOG), split failures (SF), and downstream blockage (DSB) are calculated. Additionally, traditional Highway Capacity Manual (HCM) level of service (LOS) is estimated. Even though there was a 35% increase in annual average daily traffic (AADT), the weighted average vehicle delay only increased by two seconds, LOS did not change, AOG improved by 1%, and SF and DSB remained the same. Based on the small changes in operational performance and considering the increase in traffic volume it is concluded that the implementation of the semi-automated adaptive control system had a significant positive impact in the corridor. The presented framework can be utilized by agencies to use CV data to perform before-after studies to evaluate the impact of signal timing plan changes. The presented methodology can be applied to any location where CV trajectory data is available.展开更多
基金the National Basic Research Program of China (No.2014CB046905)Innovation Project for Graduates in Jiangsu Province (No.KYLX15_1405)+1 种基金the National Natural Science Foundation of China (Nos.51274191 and 51404245)the Doctoral Fund of Ministry of Education of China (No.20130095110018)
文摘To investigate the abnormal ground pressures and roof control problem in fully mechanized repeated mining of residual coal after room and pillar mining, the roof fracture structural model and mechanical model were developed using numerical simulation and theoretical analysis. The roof fracture characteristics of a repeated mining face were revealed and the ground pressure law and roof supporting condi- tions of the repeated mining face were obtained. The results indicate that when the repeated mining face passes the residual pillars, the sudden instability causes fracturing in the main roof above the old goal and forms an extra-large rock block above the mining face. A relatively stable ＂Voussoir beam＂ structure is formed after the advance fracturing of the main roof. When the repeated mining face passes the old goaf, as the large rock block revolves and touches gangue, the rock block will break secondarily under overburden rock loads. An example calculation was performed involving an integrated mine in Shanxi province, results showed that minimum working resistance values of support determined to be reason- able were respectively 11,412 kN and 10,743 kN when repeated mining face passed through residual pillar and goaf. On-site ground pressure monitoring results indicated that the mechanical model and support resistance calculation were reasonable.
文摘BACKGROUND Primary vaginal cancer is rare and most vaginal tumors are metastatic,often arising from adjacent gynecologic structures.Primary vaginal cancers are also more common among postmenopausal women and most of these are squamous cell carcinomas,with adenocarcinomas being relatively rare.Vaginal bleeding is the most common clinical manifestation of vaginal adenocarcinoma.About 70%of vaginal adenocarcinomas are stage I lesions at the time of diagnosis,for which radical surgery is recommended.However,more advanced vaginal cancers are not amenable to radical surgical treatment and have poor clinical outcomes.Optimal treatments modes are still being explored.Here,we report a rare case of stage IIb primary vaginal adenocarcinoma for which an individually designed vaginal applicator for after-loading radiotherapy was used to achieve good tumor control.CASE SUMMARY A 62-year-old woman presented to our clinic after 3 months of abnormal postmenopausal vaginal bleeding.Gynecological examination,computed tomography(CT),and positron emission tomography-CT showed a large mass(about 5 cm)on the anterior vaginal wall.Colposcopy biopsy confirmed adenocarcinoma of vaginal origin.After three cycles of carboplatin plus paclitaxel chemotherapy,the lesion partially shrunk.The patient then received external irradiation of 45 gray(gy)in 25 fractions,which further reduced the vaginal lesion,followed by after-loading radiotherapy of 30 gy in 5 fractions with an individually designed vaginal applicator.Three months later,magnetic resonance imaging showed a slight thickening CONCLUSION Primary vaginal adenocarcinoma is rare,and prognosis is poor in most vaginal cancers of locally advanced stages,which cannot be treated with radical surgery.Better tumor control can be achieved with an individualized vaginal applicator that allows administration of a higher radical dose to the tumor area while protecting normal tissues.
文摘Updates to traffic signal timing plans are expected to either improve operations or mitigate the effects of increased volumes. Longitudinal before-after studies are important when validating changes to traffic signal systems, but they have historically required field data collection as well as deployment of extensive detection and communication equipment. These infrastructure-based techniques are costly and hard to scale. This study utilizes commercially available connected vehicle (CV) trajectory data to assess the change in performance between August 2020 and August 2021 on a 22-intersection corridor associated with the implementation of a semi-automated adaptive control system. Approximately 1 million trajectories and 13.5 million GPS points are analyzed for weekdays in August 2020 and August 2021. The vehicle trajectory data is used to compute corridor travel times and linear referenced relative to the far side of each intersection to generate Purdue Probe Diagrams (PPD). Using the PPDs, operational measurements such as arrivals on green (AOG), split failures (SF), and downstream blockage (DSB) are calculated. Additionally, traditional Highway Capacity Manual (HCM) level of service (LOS) is estimated. Even though there was a 35% increase in annual average daily traffic (AADT), the weighted average vehicle delay only increased by two seconds, LOS did not change, AOG improved by 1%, and SF and DSB remained the same. Based on the small changes in operational performance and considering the increase in traffic volume it is concluded that the implementation of the semi-automated adaptive control system had a significant positive impact in the corridor. The presented framework can be utilized by agencies to use CV data to perform before-after studies to evaluate the impact of signal timing plan changes. The presented methodology can be applied to any location where CV trajectory data is available.
