A Simplified Min-Sum Decoding Algorithm for Non-Binary LDPC Codes

Non-binary low-density parity-check codes are robust to various channel impairments. However, based on the existing decoding algorithms, the decoder implementations are expensive because of their excessive computational complexity and memory usage. Based on the combinatorial optimization, we present an approximation method for the check node processing. The simulation results demonstrate that our scheme has small performance loss over the additive white Gaussian noise channel and independent Rayleigh fading channel. Furthermore, the proposed reduced-complexity realization provides significant savings on hardware, so it yields a good performance-complexity tradeoff and can be efficiently implemented.Comment: Partially presented in ICNC 2012, International Conference on Computing, Networking and Communications. Accepted by IEEE Transactions on Communication

Pilots’ visual scan pattern and attention distribution during the pursuit of a dynamic target

Introduction: The current research is investigating pilots’ visual scan patterns in order to assess attention distribution during air-to-air manoeuvers. Method: A total of thirty qualified mission-ready fighter pilots participated in this research. Eye movement data were collected by a portable head-mounted eye-tracking device, combined with a jet fighter simulator. To complete the task, pilots have to search for, pursue, and lock-on a moving target whilst performing air-to-air tasks. Results: There were significant differences in pilots’ saccade duration (msec) in three operating phases including searching (M=241, SD=332), pursuing (M=311, SD=392), and lock-on (M=191, SD=226). Also, there were significant differences in pilots’ pupil sizes (pixel2) of which lock-on phase was the largest (M=27237, SD=6457), followed by pursuing (M=26232, SD=6070), then searching (M=25858, SD=6137). Furthermore, there were significant differences between expert and novice pilots on the percentage of fixation on the HUD, time spent looking outside the cockpit, and the performance of situational awareness (SA). Discussion: Experienced pilots have better SA performance and paid more attention to the HUD but focused less outside the cockpit when compared with novice pilots. Furthermore, pilots with better SA performance exhibited a smaller pupil size during the operational phase of lock-on whilst pursuing a dynamic target. Understanding pilots’ visual scan patterns and attention distribution are beneficial to the design of interface displays in the cockpit and in developing human factors training syllabi to improve safety of flight operations

Pilots’ visual scan pattern and situation awareness in flight operations

Introduction: Situation awareness (SA) is considered an essential prerequisite for safe flying. If the impact of visual scanning patterns on a pilot’s situation awareness could be identified in flight operations, then eye-tracking tools could be integrated with flight simulators to improve training efficiency. Method: Participating in this research were 18 qualified, mission-ready fighter pilots. The equipment included high-fidelity and fixed-base type flight simulators and mobile head-mounted eye-tracking devices to record a subject’s eye movements and SA while performing air-to-surface tasks. Results: There were significant differences in pilots’ percentage of fixation in three operating phases: preparation (M = 46.09, SD = 14.79), aiming (M = 24.24, SD = 11.03), and release and break-away (M = 33.98, SD = 14.46). Also, there were significant differences in pilots’ pupil sizes, which were largest in the aiming phase (M = 27,621, SD = 6390.8), followed by release and break-away (M = 27,173, SD = 5830.46), then preparation (M = 25,710, SD = 6078.79), which was the smallest. Furthermore, pilots with better SA performance showed lower perceived workload (M = 30.60, SD = 17.86), and pilots with poor SA performance showed higher perceived workload (M = 60.77, SD = 12.72). Pilots’ percentage of fixation and average fixation duration among five different areas of interest showed significant differences as well. Discussion: Eye-tracking devices can aid in capturing pilots’ visual scan patterns and SA performance, unlike traditional flight simulators. Therefore, integrating eye-tracking devices into the simulator may be a useful method for promoting SA training in flight operations, and can provide in-depth understanding of the mechanism of visual scan patterns and information processing to improve training effectiveness in aviation

Development and Validation of an Attitudinal-Profiling Tool for Patients With Asthma

This study was supported and funded by Mundipharma Pte Ltd. Online survey and statistical analysis were performed by Pei-Li Teh, Rachel Howard, Tsin-Li Chua and Jie Sun of Research Partnership Pte Ltd. Medical writing support was provided by Sen-Kwan Tay of Research2Trials Clinical Solutions Pte Ltd. The authors received honoraria from Mundipharma for their participation in the REALISE Asia Working Group meetings and discussions. Prof Price has Board membership with Mundipharma; and had received consultancy and speaker fees, grants and unrestricted funding support from Mundipharma; and payment for manuscript preparation and travel/accommodations/meeting expenses from Mundipharma. Profs Liam and David-Wang are members of the Asia-Pacific Advisory Board of Mundipharma. Profs Cho and David-Wang had received speaker fees from Mundipharma in the past. Dr Neira was an employee of Mundipharma Pte Ltd, Singapore. Ms Teh is an employee of Research Partnership Pte Ltd which conducted the REALISE Asia survey for Mundipharma. Prof Cho is a member of the Editorial Board of Allergy, Asthma & Immunology.Peer reviewedPublisher PD

IMPACT EXPERIMENTS IN ORTHOPAEDIC BIOMECHANICS

A better understanding of the fracture mechanism, kinematics of the anatomic structure and tissue tolerances can improve clinical prognosis and design of anthropomorphic test devices. An impact apparatus was designed to do experiments in vitro in the areas of orthopaedic biomechanics, either in hard tissue or soft tissue. METHODS: The specimens were subjected to high-speed trauma produced by an impact apparatus. This testing setup is a falling weight system which can do axial and eccentric impacts for different objectives of the orthopaedic studies. A special design was installed to assure only one impact on the specimen for biomechanical analysis. A high-speed camera was placed in front of the specimen to record the trauma event. In this study, the specimens included porcine vertebras, rabbit achilles tendons and human leg cadavers. Observations were also made to get more details by X-ray and/or by CT scan. RESULTS: Spinal fractures similar to those found clinically were successfully produced in porcine spines by impact testing. The deformations of the discs and the kinematical stability of the spinal experimental segments were also found. For the experiment on the achilles tendon, the high speed traction mechanism could produce strain injury to the specimen and get the immediate tensile force in the traction process. For the study on internal fixation for calcaneal fractures, clinically-relevant fractures under high speed impact were produced. The specimens with both longitudinal and transverse primary fracture lines were selected for simulated open reduction and internal fixation. All mechanical failures of the reconstructed calcanens occurred through the transverse primary fracture line. CONCLUSION: Impact experiment is a useful method to do fundamental research in orthopaedic biomechanics. The results in the animal model offer useful insight into bone fractures in human. The repeatability and reproducibility of animal tests offer a great opportunity to evaluate spinal fracture mechanics. The test on the achilles tendon injury was just a pilot study, and a well-designed protocol is needed to improve the results. The study on calcaneal fractures resulted in adding a longitudinal. Transfixing screw is recommended to enhance the strength of internal fixation in the presence of a transverse primary fracture line. From the above three studies, it was concluded that the impact method is an excellent experiment to produce tissue failure and/or fractures for further orthopaedic research