Investigation of the reliability and longevity of parallel systems with defects using Daniels’ sequences

The Reliability and longevity of parallel systems is studied using the example of a fibrous composite material using Daniels sequences’ and the Markov chain theory. The connection between the strength distribution function of the separate longitudinal elements forming the parallel system and the longevity distribution function of this system under cyclic loads is analyzed. The obtained models do not give direct coincidence with the experimental data but can be used for their nonlinear regressive analysis. Numerical experimental data processing examples are given.     

Can postural modification reduce kinetic and kinematic loading during the bowing postures of Islamic prayer?

As stooped postures are known to increase kinematic and kinetic loading on the lumbar spine they can be problematic for people with low back pain and postural task modification is often recommended. For the Muslim with low back pain, the bowing postures during prayer can aggravate low back symptoms. The aims of this study were to describe lumbo-sacral and pelvic tilt kinematics and lumbo-sacral kinetics during the standard bowing postures of Islam and to compare these to kinematic and kinetic data gathered during a clinically recommended modified bowing posture. The study was a repeated measures within subject cross-over design with 33 healthy male Muslim participants. 3-D motion analysis data were gathered to calculate body joint angles during the two bowing postures. A 3-D biomechanical model was then used to calculate spinal loads. Paired t-test analyses showed that the use of the modified posture resulted in significantly less pelvic tilt range of motion and anterior shear force and compressive force L5/S1, at stages 1 and 5 of bowing. Although this study was conducted with healthy young Muslim males, the use of this modified bent knee posture is recommended for all Muslims with low back pain. Clinical trials are being considered to determine the clinical utility of this postural manoeuvre as an intervention. STATEMENT OF RELEVANCE: The presence of low back pain may hinder a Muslim's ability to use the traditional Islamic bowing posture. Muslims who have low back pain may benefit from adopting a modification to the traditional bowing posture, which has been found to reduce the loads and postural demands on the lower back.     

Can postural modification reduce kinetic and kinematic loading during the bowing postures of Islamic prayer?

As stooped postures are known to increase kinematic and kinetic loading on the lumbar spine they can be problematic for people with low back pain and postural task modification is often recommended. For the Muslim with low back pain, the bowing postures during prayer can aggravate low back symptoms. The aims of this study were to describe lumbo-sacral and pelvic tilt kinematics and lumbo-sacral kinetics during the standard bowing postures of Islam and to compare these to kinematic and kinetic data gathered during a clinically recommended modified bowing posture. The study was a repeated measures within subject cross-over design with 33 healthy male Muslim participants. 3-D motion analysis data were gathered to calculate body joint angles during the two bowing postures. A 3-D biomechanical model was then used to calculate spinal loads. Paired t-test analyses showed that the use of the modified posture resulted in significantly less pelvic tilt range of motion and anterior shear force and compressive force L5/S1, at stages 1 and 5 of bowing. Although this study was conducted with healthy young Muslim males, the use of this modified bent knee posture is recommended for all Muslims with low back pain. Clinical trials are being considered to determine the clinical utility of this postural manoeuvre as an intervention.

Statement of Relevance:The presence of low back pain may hinder a Muslim's ability to use the traditional Islamic bowing posture. Muslims who have low back pain may benefit from adopting a modification to the traditional bowing posture,which has been found to reduce the loads and postural demands on the lower back.     

Teachers’ attitude regarding the use of ICT. A factor reliability and validity study

Current research examines the need for design and validation of a unifactorial scale to measure attitudes of university teachers with regard to ICT. The main goal of this study is to achieve a simple scale, composed of a single factor contributing a clearly reliable measure with acceptable content and factorial validity. A case study is presented, which has been developed with the teaching staff of the University of Salamanca (Spain). In this case study, an expert content validation was done at a first stage. After that, an attitude scale regarding the usage of ICT in teaching was applied with a representative sample of teachers (N = 2329; n = 161). An individual analysis of the items was made with the obtained results and then a Cronbach’s alpha based reliability test was carried out to show the internal consistency of the survey. Finally, an exploratory and confirmatory factor analysis was applied to prove its structural soundness and unifactoriality. The main conclusion of this paper is to offer to the scientific community a tool with adequate psychometric properties that gives added pedagogical value to the introduction of ICT in higher education teaching.     

Design and evaluation of a digital wearable ring and a smartphone application to help monitor and manage the effects of Raynaud’s phenomenon

Multimedia Tools and Applications - This paper presents the iterative research, design and evaluation phases of a digital wearable health system for monitoring, managing and possibly assisting in...     

Optimization of system reliability: a survey of problems and techniques†

The paper provides a survey of the work performed over the last two decades on the system reliability optimization. The relevant system models are first given and a set of problems, covering most cases, are formulated. Then, the optimization techniques, used for solving these problems, are briefly described, and a number of representative illustrative examples are collected. It is hoped that the paper helps in obtaining a global view of the state of art of the field of optimal reliability design.     

On the reliability of large-scale distributed systems – A topological view

In large-scale, self-organized distributed systems, such as peer-to-peer (P2P) overlays and wireless sensor networks (WSN), a small proportion of the nodes are likely to be more critical to the system’s reliability than others. This paper focuses on detecting cut vertices so that we can either neutralize or protect these critical nodes. Detection of cut vertices is trivial if the global knowledge of the whole system is known but it is very challenging when the global knowledge is not available. In this paper, we propose a completely distributed scheme where every single node can determine whether it is a cut vertex or not. In addition, our design can also confine the detection overhead to a constant instead of being proportional to the size of a network. The correctness of this algorithm is theoretically proved and the key performance gains are measured and verified through trace-driven simulations.     

Extension of the lower bound of monitor solutions of maximally permissive supervisors to non-α net systems

Traditional region-based liveness-enforcing supervisors focus on (1) maximal permissiveness of not losing legal states, (2) structural simplicity of minimal number of monitors, and (3) fast computation. Lately, a number of similar approaches can achieve minimal configuration using efficient linear programming. However, it is unclear as to the relationship between the minimal configuration and the net structure. It is important to explore the structures involved for the fewest monitors required. Once the lower bound is achieved, further iteration to merge (or reduce the number of) monitors is not necessary. The minimal strongly connected resource subnet (i.e., all places are resources) that contains the set of resource places in a basic siphon is an elementary circuit. Earlier, we showed that the number of monitors required for liveness-enforcing and maximal permissiveness equals that of basic siphons for a subclass of Petri nets modelling manufacturing, called α systems. This paper extends this to systems more powerful than the α one so that the number of monitors in a minimal configuration remains to be lower bounded by that of basic siphons. This paper develops the theory behind and shows examples.     

Towards multi-scale integrated hydrological models using the LIQUID® framework. Overview of the concepts and first application examples

Distributed hydrological models are valuable tools that can be used to support water management in catchments. However, the complexity of management issues, the variety of modelling objectives, and the variable availability of data require a flexible way to customize models and adapt them to each individual problem. Environmental modelling frameworks offer such flexibility; they are designed to build and run integrated models on the basis of reusable and exchangeable components. This paper presents the LIQUID^® framework, developed by Hydrowide since 2005. The purpose of developing LIQUID^® was to provide both easier integration of hydrological processes and preservation of their characteristic temporal and spatial scales. It suits a wide range of applications, both in terms of spatial scales and of process conceptualisations. LIQUID^® is able to synchronize different time steps, to handle irregular geometries, and to simulate complex connections between components, in particular involving feedback. The paper presents the concepts of LIQUID^® and the technical choices made to meet the above requirements, with focuses on the simulation run system and on the spatial discretization of process components. The use of the framework is illustrated by five application cases associated with contrasted spatial and temporal scales.     

Short-term test–retest reliability of the Job Content Questionnaire and Effort–Reward Imbalance Questionnaire items and scales among professional firefighters

Relatively little is known about the short-term test–retest reliability of the Job Content Questionnaire (JCQ) and Effort–Reward Imbalance Questionnaire (ERIQ). Seventeen JCQ and six ERIQ items were qualitatively reviewed by 19 firefighters in focus groups. The items were then administered twice to 81 firefighters with a time interval of 1–8 weeks. The short-term reliability of the JCQ and ERIQ items and scales with the four-point Likert item responses was at least fair or moderate with several complementary statistical methods. It improved substantially when the four-point responses were simplified into the two (‘agree’ or ‘disagree’) responses. The JCQ psychological demands and the ERIQ effort scales were among the least reliable scales and their items were most frequently indicated by the firefighters to be clarified. The responses of professional firefighters to the JCQ and ERIQ items and scales were stable during an 8-week period, particularly when dichotomous item responses were used.     

Physical employment standard for Canadian wildland firefighters: examining test–retest reliability and the impact of familiarisation and physical fitness training

Abstract

To assess the impact of repeat performances (familiarisation) plus exercise training on completion time for the Ontario Wildland Firefighter (WFF) Fitness Test circuit (WFX-FIT), normally active general population participants (n = 145) were familiarised to the protocol then randomised into (i) exercise training, (ii) circuit only weekly performances or (iii) controls. At Baseline, the WFX-FIT pass rate for all groups combined was 11% for females and 73% for males, indicating that the Ontario WFX-FIT standard had a possible adverse impact on females. Following test familiarisation, mean circuit completion times improved by 11.9% and 10.2% for females and males, respectively. There were significant improvements in completion time for females (19.8%) and males (16.9%) who trained, plus females (12.2%) and males (9.8%) who performed the circuit only, while control participants were unchanged. Post training, the pass rate of the training group was 80% for females and 100% for males.

Practitioner Summary: This paper details the impact of familiarisation plus exercise training as accommodation to mitigate potential adverse impact on initial attack wildland firefighter test performance. The results underscore the importance of test familiarisation opportunities and physical fitness training programmes that are specific to the demands of the job.     

Recursive functions of context free languages (Ⅱ)——Validity of CFPRF and CFRF definitions

In this paper we proved that the function class CFRF and its proper subclass CFPRF are respectively the partial recursive functions and primitive recursive functions of context free languages (CFLs). Also we discussed the relation between them and recursive functions defined on other domains . It is indicated that the functions of natural numbers and/or symbol strings (words) are functions of CFLs. Several frequently used primitive recursive functions on words were given, including logical connectives, conditional expressions. Also the powerful operators (bounded maximization and minimization operators) for constructing primitive recursive functions were defined. Two important nontrivial algorithms, the characteristic function of arbitrary CFL and the parse function of CFL sentences were constructed. Based on them, the method for extending or restricting function domain was described.     

Mapping the reliability of satellite-derived landcover maps—an example from the Central Brazilian Amazon Basin

Traditional methods of assessing satellite-derived landcover map accuracy are based on samples. In conditions of inaccessible terrain and lack of up-to-date contextual information, the verification of samples frequently is unfeasible. Such conditions are typical for many applications in developing countries and have been encountered by the authors when mapping the landcover of the region of Manaus in the central Brazilian Amazon Basin. Furthermore, sample-based methods fail to provide information on the spatial distribution of thematic map reliability. This article describes a procedure to derive reliability maps to accompany satellite-derived landcover maps.     

SENFIS: a Sensor Node File System for increasing the scalability and reliability of Wireless Sensor Networks applications

In the last years the Wireless Sensor Networks’ (WSN) technology has been increasingly employed in various application domains. The extensive use of WSN posed new challenges in terms of both scalability and reliability. This paper proposes Sensor Node File System (SENFIS), a novel file system for sensor nodes, which addresses both scalability and reliability concerns. SENFIS can be mainly used in two broad scenarios. First, it can transparently be employed as a permanent storage for distributed TinyDB queries, in order to increase the reliability and scalability. Second, it can be directly used by a WSN application for permanent storage of data on the WSN nodes. The experimental section shows that SENFIS implementation makes an efficient use of resources in terms of energy consumption, memory footprint, flash wear levelling, while achieving execution times similarly with existing WSN file systems.     

Addendum to “Code spectrum and the reliability function: Binary symmetric channel”

A much simpler proof of Theorem 1 from [1] is presented; we use the notation and enumeration of formulas of [1]. The text below replaces the subsection General Case in [1, Section 4, p. 271].     

The L p -norm estimation of the parameters for the Jelinski–Moranda model in software reliability

The exponential model of Jelinski and Moranda [Software reliability research, in Statistical Computer Performance Evaluation, W. Freiberg, ed., Academic Press, New York, 1972, pp. 465–484] is one of the earliest models proposed for predicting software reliability. The estimation of its parameters has been approached in the literature by various techniques. The focus of this paper is on the L _p -norm (1≤p<∞) fitting approach. Special attention is paid to the nonlinear weighted least squares (LS) estimation. We show that it is possible for the best L _p -norm estimate to not exist. As the main result, a necessary and sufficient condition for the existence of the best L _p -norm estimate is obtained. This condition is theoretical in nature. We apply it to obtain two theorems on the existence of the LS estimate. One of them gives the necessary and sufficient conditions which guarantee the existence of the LS estimate. To illustrate the problems arising with the nonlinear normal equation approach for solving the LS problem, some illustrative examples are included.