Ejection chain moves for automatic neighborhood synthesis in constrained cardinality‐minimization problems

In this paper, we deal with the problem of automatically synthesizing “good” neighborhoods for a specific class of problems, namely constrained cardinality‐minimization problems. Exploiting the peculiarity of the objective function of such problems, we develop automatic ejection chain moves that define neighborhood structures to be explored with a black‐box solver. In particular, starting from a formulation of a cardinality‐minimization problem and a feasible solution, our procedure automatically detects the “entities” involved in the problem and learns the strength of the relationships among them. This information is then used to define the characteristics of our moves that consist in ejecting one entity at a time from the solution. If one of such moves results in an infeasible solution, then feasibility is recovered by performing an additional step based on the solution of an auxiliary problem. The computational results show that, when assessed on four well‐known constrained cardinality‐minimization problems, our approach outperforms both a black‐box mixed integer programming solver and a state‐of‐the‐art model‐based neighborhood search procedure with respect to both solution quality and computing times.     

Photovoltaic field emulation including dynamic and partial shadow conditions

In this paper the development of a new laboratory prototype for the emulation of a photovoltaic (PV) field is presented. The proposed system is based on a DC/DC step-down converter topology and allows to obtain the solar array I–V curves, taking into account the environmental changes in solar irradiance and cell temperature. The DC/DC converter control strategy is deduced by using a comprehensive mathematical model of the PV field whose parameters are obtained from the knowledge of: (a) maximum power point data, measured when the PV plant power converter is running, (b) open circuit voltage and short-circuit current, measured off-line. This approach allows the most accurate representation of the PV source. Computer simulations and experimental results demonstrate that the proposed circuit acts as a highly accurate and efficient laboratory simulator of the photovoltaic array electrical characteristics both in steady state and transient conditions. Partial shading and fluctuating conditions can be reproduced too. Moreover the dynamic behaviour of the proposed laboratory emulator is suitable to its effective connection to power electronic interface to the utility or to load through a DC/DC boost converter.     

Possible role of transforming growth factor-beta in relapsing-remitting multiple sclerosis

Cerebrospinal fluid (CSF) and serum levels of transforming growth factor (TGF)-beta and soluble intercellular adhesion molecule-1 (sICAM-1) were evaluated in ten patients with definite multiple sclerosis (MS) of the relapsing-remitting type. CSF TGF-beta levels of MS patients in remission were significantly (p < 0.01) higher than of MS patients in active phase, and there was a significant inverse correlation (p < 0.05) between TGF-beta and slCAM-1 levels in the CSF of patients in both remitting and relapsing type. This is consistent with a possible down-regulation of TGF-beta on ICAM-1 expression and suggests a possible synthesis in the central nervous system of TGF-beta.     

Increased production of nitric oxide in coronary arteries during congestive heart failure

Experiments were designed to determine whether a heterogeneity of endothelium-dependent relaxations in arteries from different vascular beds exists in experimental congestive heart failure (CHF) and to determine the mediators of those responses. CHF was produced in dogs by rapid ventricular pacing for 15 d. Rings of coronary, femoral, and renal arteries with and without endothelium from control and CHF dogs were suspended in organ chambers for measurement of isometric force. In arteries contracted with prostaglandin F2 alpha, endothelium-dependent relaxations to BHT 920 (an alpha 2-adrenergic agonist) were increased in coronary arteries from dogs with CHF (maximal relaxation: control -15 +/- 9% vs CHF -92 +/- 5%; n = 5-6; P < 0.05), with a modest enhancement in renal arteries. Relaxations to adenosine diphosphate and the calcium ionophore were unchanged. Relaxations to BHT 920 in CHF were reduced by NG monomethyl-L-arginine (L-NMMA) and pertussis toxin but not by indomethacin. These data suggest that endothelium-dependent relaxations are affected heterogeneously in CHF. The enhanced response to alpha 2-adrenergic agonists in the coronary artery is mediated by nitric oxide through a mechanism sensitive to inhibition by pertussis toxin. This selective increase in endothelium-dependent relaxations in the coronary artery may contribute to preserving coronary blood flow during CHF.     

A learn‐and‐construct framework for general mixed‐integer programming problems

In this paper, we propose a new framework for finding an initial feasible solution from a mixed‐integer programming (MIP) model. We call it learn‐and‐construct since it first exploits the structure of the model and its linear relaxation solution and then uses this knowledge to try to produce a feasible solution. In the learning phase, we use an unsupervised learning algorithm to cluster entities originating the MIP model. Such clusters are then used to decompose the original MIP in a number of easier sub‐MIPs that are solved by using a black box solver. Computational results on three well‐known problems show that our procedure is characterized by a success rate larger than both the feasibility pump heuristic and a state‐of‐the‐art MIP solver. Furthermore, our approach is more scalable and uses less computing time on average.     

Enhanced Visualization of Detected 3D Geometric Differences

The wide availability of 3D acquisition devices makes viable their use for shape monitoring. The current techniques for the analysis of time‐varying data can efficiently detect actual significant geometric changes and rule out differences due to irrelevant variations (such as sampling, lighting and coverage). On the other hand, the effective visualization of such detected changes can be challenging when we want to show at the same time the original appearance of the 3D model. In this paper, we propose a dynamic technique for the effective visualization of detected differences between two 3D scenes. The presented approach, while retaining the original appearance, allows the user to switch between the two models in a way that enhances the geometric differences that have been detected as significant. Additionally, the same technique is able to visually hides the other negligible, yet visible, variations. The main idea is to use two distinct screen space time‐based interpolation functions for the significant 3D differences and for the small variations to hide. We have validated the proposed approach in a user study on a different class of datasets, proving the objective and subjective effectiveness of the method.     

A Dependent Competing Risks Model for Technological Units Subject to Degradation Phenomena and Catastrophic Failures

This paper proposes a dependent competing risks model for the reliability analysis of technological units that are subject both to degradation phenomena and to catastrophic failures. The paper is mainly addressed to the reanalysis of real data presented in a previous work, which refer to some electronic devices subject to two failure modes, namely the light intensity degradation and the solder/Cu pad interface fracture, which in previous papers, were considered independent. The main reliability characteristics of the devices, such as the probability density functions, the cause‐specific cumulative distribution function and hazard rate of each failure mode in the presence of both modes, are estimated. Likewise, the fraction of failures caused by each failure mode during the whole life of the devices or their residual life is derived. Finally, the results obtained under the proposed dependent competing risks model are compared to those obtained in previous papers. Copyright © 2015 John Wiley & Sons, Ltd.     

FRTL-5 experiment during ENEIDE mission

The FRTL-5 experiment was performed during the 10 day Italian Soyuz Mission “ENEIDE” (from April 15 to April 25, 2005) on the International Space Station. The main objectives were: 1) the validation of the FRTL5 cells as a biological system to evaluate space environment effects; 2) the investigation of the space environment-related pathophysiological mechanisms of cellular damage and/or behaviour; 3) to verify if fastgrowing cells could be differently sensitive to space environment-related effects as compared to cells in physiological standby. Because of the limited available space in the dedicated facilities and the restrictive requirements imposed by ESA, RSA and NASA, and because no pre-qualified equipment existed, all of the equipment and the procedures have been subjected to structural failure test and to severe qualification tests. Results were: 1) all the qualification procedures and tests were successful 2) Overall cell number is lower in the cultures exposed to space environment as compared to the controls reproducing the temperature conditions during the ENEIDE mission; 3) This phenomenon is most likely related to a slower growth rate in proliferative state; 4) This slow growth rate is: a) reversible, as demonstrated by the results of the growth curves, the plating and cloning efficiencies measured on the samples once they have been returned to our laboratory in Udine; b) mostly related to space effects as indicated by additional control in a clinostat. More experiments of this kind are needed to verify and validate these data and to investigate the molecular mechanisms underling the phenomenon.     

Reliability allocation methods: A systematic literature review

The choice of a reliability allocation method is not always easy or straightforward, since it depends on several factors. Some factors are directly related to the characteristics of the analyzed system, such as the level of complexity or the reliability configuration; on the other hand, additional aspects constitute boundary conditions, such as budget or experimentation time. In this scenario, the purpose of the present research is to present a systematic literature review on reliability allocation, proposing a guideline to choose the optimal allocation method in respect to the desired application, available resources, and required accuracy. The proposed review analyzes allocation methods in literature, determining main features and area of application. Motivated by a lack of a comprehensive methods summarization present in literature, our research goal is to assist practitioners in choosing a well-suited method and to provide an overview, to support academics in conducting new research in this area. The results of the performed analysis are synthetized according to several criteria. The results are summarized and categorized in different clusters for each individuated application field. The proposed summarization design allows an easy and rapid consultation.     

Combined microwaves and convection heating: A conjugate approach

Microwave treatment has been gaining increasing recognitions in the food industry and household frameworks alike. Better energy and finishing efficiencies can be obtained by adding an additional transport mechanism, such as forced air convection heating. In this work, transient distributions of temperature and moisture during the combined treatment is analyzed by a full computational fluid dynamics model, coupled with custom moisture diffusion and evaporation notations.