System Interval Research Articles

Multicentre service evaluation of presentation of newly diagnosed cancers and type 1 diabetes in children in the UK during the COVID-19 pandemic

BackgroundThe COVID-19 pandemic led to changes in patterns of presentation to emergency departments. Child health professionals were concerned that this could contribute to the delayed diagnosis of life-threatening conditions, including...

Accelerating diagnosis for childhood brain tumours: an analysis of the HeadSmart UK population data

BackgroundHeadSmart, a public and professional awareness campaign, was launched to enhance awareness of brain tumour symptomatology identified in the Royal College of Paediatrics and Child Health, National Institute for Health...

A fuzzy α-cut optimization analysis for vibration control of laminated composite smart structures under uncertainties

As a high performance and specific mechanically tailored material, composite structures present high structural behavior sensitivity to small variations in geometry or material properties. Some of these uncertainties are intrinsically related to the manufacturing process but others are usual uncertainty in material properties. A fuzzy interval analysis methodology is proposed in this paper in order to evaluate the structural behavior of laminated composite smart structures under vibration control and uncertain parameters. A Particle Swarm Optimization algorithm is used to search for input parameters in order to minimize and maximize system outputs by an anti-optimization and thus build their envelopes. Each input parameter has interval values defined by α-cut levels and interpolated by the Fuzzy reasoning. This methodology is applied to a smart structure of laminated composite material with attached piezoelectric patches and controlled by an optimal control regulator. System's interval outputs like natural frequency, mechanical vibration, and electric control input energy are investigated taking into account uncertainties in the composite and piezoelectric material properties, ply angles and layer thickness. Finally, it is concluded that these uncertainties may affect the control performance since it was found significant modifications in the dynamic behavior and therefore this should be accounted in the design stages.

Factors influencing time to seeking medical advice and onset of treatment in women who are diagnosed with breast cancer in Serbia.

Streamlining the diagnosis is a key factor in improving the treatment outcomes for breast cancer. The aim of this study was to determine factors influencing time to seeking medical advice and treatment onset in women who are diagnosed with breast cancer in Serbia. The study was a multicenter, cross-sectional national survey, performed at 10 oncology centers in Serbia. Time intervals spent throughout the complex diagnostic pathway were evaluated using a validated questionnaire administered to women with breast cancer (n=800). Total interval (TI) was determined using predefined time scales, including one referring to patient interval (PI), and several related to health care system interval (SI). Mean PI, SI, and TI were 4.5, 9.2, and 12.9weeks, respectively; 20% of patients had a PI>12weeks. Based on the multivariate regression model, longer PI was associated with perceived lack of time and personal disregard or trivialization of detected symptoms and signs. Women who were supported by family members or friends and had at least a secondary level education tended to have a shorter PI. Longer PI was correlated with a longer SI, while regular self-examination, having been diagnosed by an oncologist, and living in a major city were associated with shorter SI. Several factors, related to psychological, demographic, behavioral, and health system characteristics, determined both the time to seeking medical advice and treatment onset for breast cancer. These findings support review and refining of national strategies and policies to promote early detection, diagnosis, and treatment of breast cancer.

Development of a Quality Measure for the Characterization of Guaranteed Solution Sets to ODEs in Engineering

Solving initial value problems (IVPs) for ordinary differential equations (ODEs) is a common task in many scientific fields. Over the last decades, several different verified techniques have been developed to compute enclosures of the exact result numerically. The obtained bounds are guaranteed to contain the corresponding solution to the IVP and can be used to verify whether a given control strategy is admissible with respect to state and input constraints. Ideally, we aim at calculating tight enclosures over sufficiently long time intervals for systems with uncertainties given as sets. However, the existing solvers are not always equal in attaining this goal. On the one hand, the quality of the obtained results depends strongly on the types of ODEs that describe a given dynamical system. On the other hand, a great influence of the considered uncertainties can be observed. Our general aim is to provide assistance in choosing an appropriate verified IVP solver with its most suitable ‘tuning parameters’ for the application at hand. In this paper, we describe briefly the basics of verified IVP solvers. After a short introduction to a possible framework for the fair comparison of different approaches, we concentrate on possibilities to quantify the conservativeness introduced by verified solvers for problems with uncertainties.

On temporal logic programming using Petri nets

A methodology for modeling temporal (time-sensitive) aspects of discrete-event systems is presented. A formalism of temporal logic which incorporates both point and interval descriptions of time is formulated, which is an extension of Alien's interval logic. A formal axiomatic system of this point-interval logic is presented. A graph model is shown to implement the axiomatic system of point-interval logic. This graph-based approach transforms the system's specifications given by temporal statements into a graph structure. The graph-based temporal inference engine identifies temporal ambiguities and errors (if present) in the system's specifications, infers new temporal relations among system's intervals, and identifies the user-defined intervals of interest.

On the interval reliability of systems modelled by finite semi-Markov processes

In this paper, semi-Markov models of repairable systems are considered whose finite state space is partitioned into two sets, the set of ‘up’ states, U, and the set of ‘down’ states, D. The focus of attention is the system's interval reliability which is defined as the probability of the system being in U throughout a given time interval [t, t + x] where t, x ϵ [0, +∞) are fixed. Two results in the Laplace transform domain are obtained for the interval reliability. The first one is a closed form expression for the double Laplace transform with respect to both variables t and x. The second result is concerned with a closed form expression of the (single) Laplace transform of the interval reliability with respect to the variable t under the additional assumption that the modelling semi-Markov process is Markovian on U. As an example, the semi-Markov model of a two-unit repairable system is considered. The steady-state behaviour of the system's interval reliability is examined by a Tauberian theorem.

Boundary-value descriptor systems: well-posedness, reachability and observability

In this paper we introduce the class of two-point boundary-value descriptor systems (TPBVDS), discrete-time systems described by possibly linear dynamics and a set of boundary conditions constraining the values of the system 'state' at the two endpoints of the system's interval of definition. By introducing a standard form for regular pencils we obtain a new and simple generalized Cayley-Hamilton theorem that simplifies our investigation of well-posedness, Green's function solutions, and reachability and observability for TPBVDS. There are two distinct notions of reachability and observability that one can define for TPBVDS, associated with processes that propagate inward from and outward toward the boundaries. We investigate each of these in detail, obtaining, among other things, far simpler forms for the reachability and observability results than found previously in the literature. In addition, we describe several methods for the efficient solution of TPBVDS, one involving recursions from each end of t...