The Numerical Analysis for Parametric Resonance of Multicable System considering Interaction between Adjacent Beam Portions

The investigation aims to propose a refined model to analyze the parametric resonance under multicable systems such as cable-stayed bridges. Considering the interaction between the adjacent beam portions, the shear difference is applied to modify the vibration equations derived from the multi-degree-of-freedom stiffness method. Furthermore, the difference method is adopted to make the equations more accessible for numerical analysis. The comparison results indicate that the refined model exhibits the key character of parametric resonance and also further verified the simulation methods. The consequences show that the cable will resonate at the fundamental frequency under the support excitation. In particular, when resonance occurs, most of the energy in the subsystem is transferred to the cable, resulting in the resonance amplitude of the beam portion being weakened to some certain extent. Moreover, the global resonance will have a sufficient excitation on the local resonance only when the resonance condition is satisfied.

Modeling Movement Times and Success Rates for Acquisition of One-dimensional Targets with Uncertain Touchable Sizes

In touch interfaces, a target, such as an icon, has two widths: the visual width and the touchable width. The visual width is the target's appearance, and the touchable width is the area in which users can touch a target and execute an action. In this study, we conduct two experiments to investigate the effects of the visual and touchable widths on touch pointing performance (movement time and success rate). Based on the results, we build candidate models for predicting the movement time and compare them by the values of adjusted R^2 and AIC. In addition, we build a success rate model and test it through cross-validation. Existing models can be applied only to situations where the visual and touchable widths are equal, and we show that our refined model achieves better model fitness, even when such widths are different. We also discuss the design implications of the touch interfaces based on our models.

Iterative technique for a beam lying on a transversely isotropic foundation

The effect of the foundation heterogeneity on the mechanical behaviour of a beam on Vlasov soils is discussed. According to a refined Vlasov soil model, the static problem of beams lying on transversely isotropic soils can be solved by an iterative method. In this paper, based on the energy variational principle, the differential equations for beams under an axial force on refined Vlasov foundations are derived. The methods for solving the internal forces and deformations of beams lying on refined elastic foundations are given. Additionally, an equation for the attenuation parameters is also established, and the characteristic parameters of the refined model are solved by iterative technique. Numerical results show that the foundation heterogeneity have a influence on the deformations and internal forces of the beam-soil system. Moreover, relatively accurate characteristic parameters can be obtained through the iterative process. The refined Vlasov model has broad application prospects.

Improved models for operation modes of complex compressor stations

We study combinatorial structures in large-scale mixed-integer (nonlinear) programming problems arising in gas network optimization. We propose a preprocessing strategy exploiting the observation that a large part of the combinatorial complexity arises in certain subnetworks. Our approach analyzes these subnetworks and the combinatorial structure of the flows within these subnetworks in order to provide alternative models with a stronger combinatorial structure that can be exploited by off-the-shelve solvers. In particular, we consider the modeling of operation modes for complex compressor stations (i.e., ones with several in- or outlets) in gas networks. We propose a refined model that allows to precompute tighter bounds for each operation mode and a number of model variants based on the refined model exploiting these tighter bounds. We provide a procedure to obtain the refined model from the input data for the original model. This procedure is based on a nontrivial reduction of the graph representing the gas flow through the compressor station in an operation mode. We evaluate our model variants on reference benchmark data, showing that they reduce the average running time between 10% for easy instances and 46% for hard instances. Moreover, for three of four considered networks, the average number of search tree nodes is at least halved, showing the effectivity of our model variants to guide the solver’s search.

ОЦІНКА ЕФЕКТИВНОСТІ ФОРМ КРИЛА ВАЖКИХ ЛІТАКІВ НА ОСНОВІ ЇХ КОЕФІЦІЄНТА ЕЛІПТИЧНОСТІ

The most important step in the choice of the parameters of trapezoidal wings is to ensure the design of the change in the circulation on their scope, as close as possible to the distribution of circulation in the elliptic wing as possible, which leads to the minimum value of its inductive resistance at a given value of the lift.Recently, when solving such a problem, the method of forming the main geometric sizes of the wing was distributed in terms of the equality of the so-called forms of trapezoidal () and equal to the elliptic area () wings.This approach turned out to be quite effective in the formation of geometric parameters of the wings of light and medium aircraft.However, for heavy aircraft with a large area of the wing, the plan of which is formed by three and more trapezes, there were difficulties in determining the coefficients of forms, which required the specified models for determining the coefficients of ellipticity () in assessing the effectiveness of heavy aircraft wings with their multivariate modification changes.The use of a refined model of the ellipticity coefficient is made on the examples of evaluating the effectiveness of trapezoidal wings of such heavy aircraft as IL-86, C-5A, IL-76 and An-124-100. It has been established that the wings of IL-76 and C-5A airplanes are the highest ellipticity. An-124-100 domestic aircraft wing is somewhat inferior to them in the magnitude of the ellipticity coefficient, which should be borne in mind when developing subsequent modifications of this aircraft.

Accuracy assessment methods for physiological model selection toward evaluation of closed-loop controlled medical devices

Physiological closed-loop controlled (PCLC) medical devices are complex systems integrating one or more medical devices with a patient’s physiology through closed-loop control algorithms; introducing many failure modes and parameters that impact performance. These control algorithms should be tested through safety and efficacy trials to compare their performance to the standard of care and determine whether there is sufficient evidence of safety for their use in real care setting. With this aim, credible mathematical models have been constructed and used throughout the development and evaluation phases of a PCLC medical device to support the engineering design and improve safety aspects. Uncertainties about the fidelity of these models and ambiguities about the choice of measures for modeling performance need to be addressed before a reliable PCLC evaluation can be achieved. This research develops tools for evaluating the accuracy of physiological models and establishes fundamental measures for predictive capability assessment across different physiological models. As a case study, we built a refined physiological model of blood volume (BV) response by expanding an original model we developed in our prior work. Using experimental data collected from 16 sheep undergoing hemorrhage and fluid resuscitation, first, we compared the calibration performance of the two candidate physiological models, i.e., original and refined, using root-mean-squared error (RMSE), Akiake information criterion (AIC), and a new multi-dimensional approach utilizing normalized features extracted from the fitting error. Compared to the original model, the refined model demonstrated a significant improvement in calibration performance in terms of RMSE (9%, P = 0.03) and multi-dimensional measure (48%, P = 0.02), while a comparable AIC between the two models verified that the enhanced calibration performance in the refined model is not due to data over-fitting. Second, we compared the physiological predictive capability of the two models under three different scenarios: prediction of subject-specific steady-state BV response, subject-specific transient BV response to hemorrhage perturbation, and leave-one-out inter-subject BV response. Results indicated enhanced accuracy and predictive capability for the refined physiological model with significantly larger proportion of measurements that were within the prediction envelope in the transient and leave-one-out prediction scenarios (P < 0.02). All together, this study helps to identify and merge new methods for credibility assessment and physiological model selection, leading to a more efficient process for PCLC medical device evaluation.

Glucosamine-6-Phosphate Synthase de Mycobacterium tuberculosis um estudo in silico para predição de um modelo tridimensional refinado

Tuberculosis is one of the main causes of death by an infectious agent in the world, according to the World Health Organization. Studies indicate that enzymes involved in the biosynthesis of uridine diphospho-N-acetylglucosamine are essential for the life cycle of the bacterium. One of these enzymes is glucosamine-6-phosphate synthase (GlmS), which does not have a three-dimensional structure available in the protein database on the internet. In this work, structural bioinformatics methods (comparative modeling and molecular refinement) were used to build a refined three-dimensional model for the GlmS enzyme of Mycobacterium tuberculosis. The model was generated using four templates structures (crystallographic). The results obtained for the stereochemical and general parameters of the refined model were better than the original model and similarto those templates structures, validating the refined model.