Evaluation of the Impact of Driver Behavior on Back of Queues Events in Work Zones Using the SHRP2 Naturalistic Driving Study Data

The SHRP2 Naturalistic Driving Study was used to evaluate the impact of various work zone and driver characteristics on back of queue safety critical events (crash, near-crash, or conflicts) The model included 43 SCE and 209 “normal” events which were used as controls. The traces included representing 209 unique drivers. A Mixed-Effects Logistic Regression model was developed with probability of a SCE as the response variable and driver and work zone characteristics as predictor variables. The final model indicated glances over 1 second away from the driving task and following closely increased risk of an SCE by 3.8 times and 2.9 times, respectively. Average speed was negatively correlated to crash risk. This is counterintuitive since in most cases, it is expected that higher speeds are related to back of queue crashes. However, most queues form under congested conditions. As a result, vehicles encountering a back of queue would be more likely to be traveling at lower speeds.

Suggestion of Criteria and Certification Process to Secure the Safety of Railway Software

One of the significant differences between the digital system and the analog system is software. The software takes charge of the functions and the management of the digital system. Nowadays railway equipment has begun to be designed and implemented based on digital technology with online and real time performance to achieve high speed and high density operation. The software is designed, coded and implemented into the system, and controls hardware components in order to satisfy the functional requirements of the system. As the functions that are implemented by software are increased, it becomes very difficult to predict the soil-ware failures because of its complexity. Therefore, it has become one of the key issues how to assure that the sottware is reliable, safe and secure. In this paper, the safety criteria are suggested to secure the software safety for the field of railway system. Characteristic of railway software and review safety related standards are analyzed. The authors also suggest development methodology and certification procedure for the developer and assessor to easily make safety critical railway software with following the safety criteria.

Cooperative game penetration guidance for multiple hypersonic vehicles under safety critical framework

The rapid development of the anti-missile weapon technology brings new challenges to the cooperative penetration strategy solution and the guidance law design for Hypersonic Vehicles(HVs).This paper studies the coordinated game penetration guidance problem for multiple hypersonic vehicles faced with space threat areas.A scheme for seeking cooperative game penetration guidance strategy under safety critical control framework is presented.In this scheme,a multiHV cooperative game model is proposed in a minimum optimization form which can simplify the solving process and accelerate the computing speed.Then,a second-order control barrier function is developed to transform the implicit nonlinear constraints of the proposed model into linear ones.In order to obtain better performance of guidance strategy,a composite guidance law under the safety critical control framework is presented to allocate guidance strategies appropriately in the whole process.It is shown that the proposed scheme can guarantee successful penetration while avoiding threat areas.Finally,a comparative simulation with a two-on-three game is conducted to verify the effectiveness of the proposed method.

Protocol for laparoscopic cholecystectomy: Is it rocket science?

Laparoscopic cholecystectomy(LC) does not require advanced techniques, and its performance has therefore rapidly spread worldwide. However, the rate of biliary injuries has not decreased. The concept of the critical view of safety(CVS) was first documented two decades ago. Unexpected injuries are principally due to misidentification of human factors. The surgeon's assumption is a major cause of misidentification, and a high level of experience alone is not sufficient for successful LC. We herein describe tips and pitfalls of LC in detail and discuss various technical considerations.Finally, based on a review of important papers and our own experience, we summarize the following mandatory protocol for safe LC:(1) consideration that a high level of experience alone is not enough;(2) recognition of the plateau involving the common hepatic duct and hepatic hilum;(3) blunt dissection until CVS exposure;(4) Calot's triangle clearance in the overhead view;(5) Calot's triangle clearance in the view from underneath;(6) dissection of the posterior right side of Calot's triangle;(7) removal of the gallbladder body; and(8) positive CVS exposure. We believe that adherence to this protocol will ensure successful and beneficial LC worldwide, even in patients with inflammatory changes and rare anatomies.

Laparoscopic cholecystectomy for gangrenous cholecystitis in around nineties: Two case reports

BACKGROUND Gangrenous cholecystitis is a form of acute cholecystitis which involves gangrenous alterations in the gallbladder wall and it often follows an acute and serious course.We herein report on two cases of very elderly people diagnosed early with gangrenous cholecystitis,who safely underwent laparoscopic cholecystectomy(LC)and both demonstrated a good outcome.CASE SUMMARY Case 1:An 89-year-old female.She underwent abdominal contrast-enhanced computed tomography(CECT)due to abdominal pain and diarrhea.Her gallbladder wall indicated the absence of contrast enhancement,thus leading to diagnosis of gangrenous cholecystitis and she therefore underwent LC.Although her gallbladder demonstrated diffuse necrosis and it was also partly perforated,she was able to be discharged without any serious complications.Case 2:A 91-year-old female.She made an emergency visit with a chief complaint of abdominal pain.Abdominal CECT revealed swelling of the gallbladder and an ambiguous continuity of the gallbladder wall.She was diagnosed with gangrenous cholecystitis and underwent LC.Her gallbladder had swelling and diffuse necrosis.Although her preoperative blood culture was positive,she showed a good outcome following surgery.CONCLUSION Although a definite diagnosis of gangrenous cholecystitis is difficult to make prior to surgery,if an early diagnosis can be made and appropriate treatment can be carried out,then even very elderly individuals may be discharged without major complications.

A high order collaboration and real time formal model for automatic testing of safety critical systems

The need for safety critical systems （SCS） is both important and urgent, and their evaluation and verification are test-dependent. SCS are usually complex and very large, so manual testing of SCS are infeasible in practice, and develop- ing automatic test approaches for SCS has become an impor- tant trend. This paper defines a formal semantics model for automatic test of SCS, called AutTMSCS, which describes behaviors in SCS testing. The model accommodates the high order collaboration in real time and temporariness of SCS testing. Testing tasks, test equipment and products under test are abstracted and architected in three layers, and a method for automatic testing is given. Based on extended label tran- sition system （LTS）, the convergency and correctness of the model are proved to demonstrate the computability of the model, indicating that the testing process of SCS can be au- tomatic.