Reliability Analysis of Aircraft Air Conditioning Packs

Air conditioning packs of aircraft are subject to a number of failures like other aircraft components. However, the number and results of unexpected failures in the Kingdom are expected to be more severe than the corresponding failures in many other countries due to climatic conditions. This paper examines the time-to failure distribution of Boeing 737 air conditioning packs by using Weibull method which is one of the most useful tools in aerospace system reliability analysis. Forecasting of part failure rates are very important for maintenance planning since it allows for predicting the future failures and determining the overhaul period or scheduled inspection period at an acceptable probability of failure

Application of Cardio-Forecasting for Evaluation of Human—Operator Performance

The paper presents the results of the development of the cardio-forecasting technology, which introduces a new method to monitor the state of human-operator, which is characteristic for the given production conditions and for individual operators, to predict the moment of exhaustion of his/her working capacity. The work aims to demonstrate the unique, distinctive features of the cardio-forecasting technology for predicting an individual limit of his/her working capacity for each person. A unique methodology for predicting individually for each person the moment when he/she reaches the limit of his/her working capacity is based on a spectral analysis of a human phonocardiogram in order to isolate the frequency component located at the heart contraction frequency. The trend of the amplitude of this component is approximated by its model; consequently, the coefficients of the trend model are determined. They include the operator’s operating time until his/her working capacity is exhausted. A methodology for predicting the moment when he/she reaches the limit of his/her working capacity for each person individually and assessment based on this degree of criticality of their condition will be realized as a software application for smartphones using the Android operating system

Online routing and searching on graphs with blocked edges

We study routing and searching decisions of a search-and-detection (SDT) team on a road network under online uncertainty setting. Given an undirected edge-weighted bounded graph, a static target is positioned at an unknown vertex among potential target vertices in the graph. A non-negative search cost is given on each of the potential target vertices. The target is detected once the SDT searches its corresponding vertex. There may be some non-recoverable online blockages in the graph, but the existence of blockages is unknown to the SDT initially. If a blockage exists in the graph, it is disclosed online once the SDT visits one of its end-vertices. The graph stays connected when the blockages are omitted from it. The SDT begins from a certain vertex and aims to identify a route without any blocked edges which detects the target with minimum total traveling and search cost. We analyze this problem from a competitive analysis perspective under two scenarios with and without blockages. For the scenario with blockages, we provide a tight lower bound on the competitive ratio of deterministic solutions, an optimal deterministic solution, a randomized solution with a bounded expected competitive ratio, together with lower and upper bounds on the expected competitive ratio of the optimal randomized solutions. For the scenario without blockages, we provide tight lower bounds as well as optimal deterministic and randomized solutions

Pain Intensity and Its Objective Determinants Following Implant Surgery and Sinus Lifting: A 1-Year Prospective Study

Objectives: The main goal of this study was to evaluate the relationship between postoperative pain and short-term implant survival. Objective parameters, such as implant-related factors (type, diameter, length) and the surgical approach were also assessed to correlate them with pain. Materials and Methods: This prospective, single-center study consisted of 144 patients scheduled for the surgical placement of one or more implants either with conventional surgery or with sinus-lifting together. All patients were asked to complete a questionnaire form of pain with a visual-analog scale (VAS, 1–10) for 7 days following surgery. The association of pain scores at each time-point was assessed on implant- and surgery-related factors. Results: The overall cumulative survival rate of 546 implants in 144 patients was 98.17 % (10 implants lost) after 1-year follow-up. No statistical difference was found in pain (VAS) scores between patients with loss and survived implants at any observation period. The length and diameter of placed implants and the presence of a sinus-lifting procedure did not influence the pain scores at any period (P > 0.05). In patients with bilateral sinus lifting, the decrease in pain scores was significant after 3 days (P < 0.05), whereas it was significant after 6 hours for the conventionally treated group (P < 0.01). Although no severe pain was reported at any time, this study found a significant difference in pain intensities among different implant brands. Conclusions: This study was able to show that increased postoperative pain is not a sign of early implant failure. In addition to this, the implant dimensions and presence of sinus lifting procedure did not influence the pain experience. However, the bilateral sinus lifting prolongs the recovery time.Keywords: Dental implant, pain, postoperative, sinus lifting, surger