Traffic management in underground mines,especially on production ramps,is a difficult problem to optimize and control.Most operations use one of a few common policies;e.g.,the so-called ‘‘lock-out" and‘‘loade...Traffic management in underground mines,especially on production ramps,is a difficult problem to optimize and control.Most operations use one of a few common policies;e.g.,the so-called ‘‘lock-out" and‘‘loaded-vehicle-priority" policies.The work presented in this paper uses discrete-event simulation to study the efficiency of multiple policies.Based on simulation results,an improvement to the common lock-out policy is proposed.This new policy utilizes the rules of the lock-out policy but integrates an option that allows a group of vehicles to be given temporary priority in a certain direction of travel.Quantitative results are provided and,based on these,a systematic technique for ramp design that aims to optimize the efficiency of underground mine ramp traffic flow is described.展开更多
Objective： Tracheobronchial injuries are defined as injuries involving the trachea and/or bronchi from the level of the cricoid cartilage extending up to the division of the bronchi. We present a case series with mos...Objective： Tracheobronchial injuries are defined as injuries involving the trachea and/or bronchi from the level of the cricoid cartilage extending up to the division of the bronchi. We present a case series with most of the tracheobronchial injuries found to be sustained after penetrating trauma. Methods： A retrospective review was performed at the Aga Khan University, Karachi, Pakistan. From January 2004 to December 2009, 168 patients with thoracic trauma were treated, of whom 15 were recognized to have major tracheobronchial and pulmonary injuries. Results： The average age was 3 l years with most of the patients being male （14：1）. Among them,11 patients had penetrating trauma as the main cause of injury, 3 patients had blunt trauma from road traffic accidents, only 1 patient had combined trauma （blunt and penetrating trauma）. Eightpatients were diagnosed based on radiological findings. All the patients were treated surgically. Lobectomy was the most common intervention performed in 7 patients. The mortality rate was 7% （1 patient）. Most patients survived with no sequelae （10 patients） while 5 survived with disability. We found that penetrating trauma was the leading cause of injury in our series. The severity of injury depends upon the weapon causing the trauma. Patients in our series had multiple injuries and required surgical management. Conclusions： Tracheobronchial injuries are rare but potentially life threatening. They require quick diagnosis and management. Diagnosis tends to be difficult since there are no specialised diagnostic modalities available at present.展开更多
基金funded by the Natural Science and Engineering Research Council of Canada (NSERC) under project CRDPJ 44SBO4-12funding provided by Barrick Gold Corporation and Peck Tech Consulting Ltd
文摘Traffic management in underground mines,especially on production ramps,is a difficult problem to optimize and control.Most operations use one of a few common policies;e.g.,the so-called ‘‘lock-out" and‘‘loaded-vehicle-priority" policies.The work presented in this paper uses discrete-event simulation to study the efficiency of multiple policies.Based on simulation results,an improvement to the common lock-out policy is proposed.This new policy utilizes the rules of the lock-out policy but integrates an option that allows a group of vehicles to be given temporary priority in a certain direction of travel.Quantitative results are provided and,based on these,a systematic technique for ramp design that aims to optimize the efficiency of underground mine ramp traffic flow is described.
文摘Objective： Tracheobronchial injuries are defined as injuries involving the trachea and/or bronchi from the level of the cricoid cartilage extending up to the division of the bronchi. We present a case series with most of the tracheobronchial injuries found to be sustained after penetrating trauma. Methods： A retrospective review was performed at the Aga Khan University, Karachi, Pakistan. From January 2004 to December 2009, 168 patients with thoracic trauma were treated, of whom 15 were recognized to have major tracheobronchial and pulmonary injuries. Results： The average age was 3 l years with most of the patients being male （14：1）. Among them,11 patients had penetrating trauma as the main cause of injury, 3 patients had blunt trauma from road traffic accidents, only 1 patient had combined trauma （blunt and penetrating trauma）. Eightpatients were diagnosed based on radiological findings. All the patients were treated surgically. Lobectomy was the most common intervention performed in 7 patients. The mortality rate was 7% （1 patient）. Most patients survived with no sequelae （10 patients） while 5 survived with disability. We found that penetrating trauma was the leading cause of injury in our series. The severity of injury depends upon the weapon causing the trauma. Patients in our series had multiple injuries and required surgical management. Conclusions： Tracheobronchial injuries are rare but potentially life threatening. They require quick diagnosis and management. Diagnosis tends to be difficult since there are no specialised diagnostic modalities available at present.
