Introduction to the Special Issue on Computer-Aided Uncertainty Modeling and Reliability Evaluation for Complex Engineering Structures

1 Summary With the advancement of science and technology,complex engineering structures are widely used in extreme environments[1].In equipment service,many uncertainty factors significantly affect safety and reliability[2–5].Therefore,ensuring high reliability of structures has become an important research direction in engineering design.At the same time,the importance of equipment health management of complex engineering structures is becoming increasingly prominent[6–8].Computer-aided uncertainty modeling and reliability assessment have become key tools,and finite element simulation and algorithmic innovation play a key role in the reliability analysis of complex equipment[9,10].These techniques can accurately simulate stress and damage accumulation under various operating environments,providing engineers with important decision support and optimization solutions.

The role of physical properties in explosive welding of copper to stainless steel

This paper investigates the effects of the physical properties on the microstructure and weldability of explosive welding by joining two metals with a significant contrast in thermophysical properties:stainless steel and copper.Sound welds between stainless steel and copper were obtained,and the interfacial morphology was wavy,regardless of the position of the materials.The weldability of dissimilar pairs was found to be more dependent on the relationship between the physical properties of the base materials than on the absolute value of the material property.When there is a significant difference in thermal conductivity between the flyer and the base plate,together with a material with a low melting temperature,the weldability of the pair is often poor.The relative position of the plates affects the interfacial microstructure even when similar morphologies are found.For the metallic pairs studied,the wave size was bigger for the configuration in which the ratio between the density of the flyer and the density of the base plate is smaller.The same phenomenon was observed for the impedance:bigger waves were found for a smaller ratio between the impedance of the flyer and the impedance of the base plate.

Neuropsychological Aspects of Aging and Driving for Inclusive Automotive Interior Design

As people grow older, their cognitive functions undergo changes which may result in uncomfortable driving situations and even increase the risk of accidents. This research aims to understand the neuropsychological aspects of healthy aging and their possible relationship in changes in motor performance or ability. The research methodology is descriptive and includes a collection of basic studies in the scope of neuroscience, driving tasks, and older driver behavior. The final analysis points to certain changes in the functioning of the cerebral cortex and its connections as being responsible for poor performance in some basic driving tasks, but which can be compensated for by means of adapted mechanisms in motor vehicles. This study may contribute as a methodological tool, to the automobile design process, for the selection of Advanced Driver Assistance Systems (ADAS) or other emerging technologies which can compensate cognitive changes, improve safety, comfort and inclusion of older drivers in the future of automobile interior design. We conclude that in normal aging, people may present some cognitive deficits especially linked to the frontal and parietal lobe, which interfere with the necessary driving skills albeit not with the dangerous ones and can be compensated by technological solutions. The main innovation of this article is related to the bibliographical compilation and critical analysis in terms of identifying the neuropsychological aspects of normal human aging and car driving and its relationship with possible contributions from vehicular technology, as well its consider future trends in automotive interior design that should be analysed with caution in order to users inclusion.

Small Scale Refrigerators and Freezers： Thermal Improvements in the Envelope

Like in other sectors of activity, the sustainability in refrigeration systems is a mandatory goal to achieve, namely at house holdings, bars and restaurants, where small-scale refrigerators and freezers are widely used. The aim of this work is to demonstrate experimentally, trough measurements carried out in these equipments, the improvement that can be achieved if several modifications are implemented in traditional household refrigeration systems. In addition, it was also simulated and analysed experimentally a slightly different equipment, a refrigeration system used for draught beverages. Both systems work on a single vapour compression refrigeration with R-134a as working fluid. In the end, by implemented the modifications tested in the virtual model, it was possible to improve their thermal behaviour, a decrease in electrical energy consumption, as well as, the associated CO2 emissions reduction can be attained. In this project, the CFD （Computational Fluid Dynamics） soffware--ANSYS Fluent was used to simulate the ambient temperature and velocity fields inside the refrigerator and in that way to validate the measured results.

A Remote Sensing Characterization of the Effects of Anastrepha striata ＆ Anastrepha ludens on Guava Cultures in Mexico

Detection of the presence of Anastrepha striata and Anastrepha ludens in guava cultures is presently done in Mexico by actually catching the flies in strategically located traps. The objective of this study is to show that it is possible to locate areas with the presence or absence of flies by remote sensing means, thereby simplifying the traditional way of detection of these plagues. In the field, groups of traps were selected where flies had been captured, as well as areas in which there was no capture in the traps. The radiometric signatures of whole trees and leaves were obtained, showing measurable differences between those specimens affected by the plague and those unaffected. Next we selected a SPOT5 image of 2007 corresponding to the study area in Calvillo, State of Aguascalientes, in Mexico, one of the major areas of guava cultures in the country. A supervised classification of the image allowed for the location of guava cultures in it. The guava culture areas obtained from this classification were validated comparing them to available maps of the cultured areas. Spectral signatures for the classes were derived from the image data. The separability of pairs of classes was also evaluated in order to maximize it. The IR/R （infrared to red ratio） ratio of the image bands was evaluated in 80 × 80 pixels around the locations of five traps where flies had been captured, and around five locations where the traps had not captured flies. Only the pixels where guava cultures were present were included in the analysis, other types of vegetation and soil coverage were rejected. We found that the index distributions with flies captured and those without flies captured cluster in two well-separated groups. We note that plotting the whole distribution of pixels around a trap yields a diagnostic view of the area, and individual index values do not provide such a view, since values with the flies＇ presence and without these overlap to some extent. Further analyses of other trap locations confirmed this separation and also revealed a third group of intermediate values between the two above, that are interpreted as locations in which the guava cultures are affected by the plague at an early stage of development, where the flies are not captured by the traps since they do not yet hatch. We concluded that it is possible to use remote sensing techniques to identify the presence ofAnastrepha striata and Anastrepha ludens in cultures of Psidium guajava L., even probably at early stages of development of the plague.

Psychological and Cognitive Aspects of Ageing： The Importance of Driving on Senior Living

This research aims to understand the psychological, the social and cognitive aspects of ageing and assess the relevance of driving a personal automobile to seniors. We know that biological ageing is an inescapable fact, but is there also a psychological and a cognitive ageing？ If so, is it related to getting older or to other factors？ How relevant is continuing to drive to seniors, and how can the activity influence psychological and cognitive types of their ageing and self well-being？ To answer these questions, we study several authors and concepts about mental health, development of ageing and their relationship to driving. We also explore psychological and cognitive changes associated with ageing, the principal behavioural changes of healthy senior people （with normal cognitive function） and MCI （mild cognitive impairment）, as well as how driving inhibition can induce and affect psychological and cognitive characteristics. We conclude that low mental functioning is caused by a set of biological, psychological and social factors, connected in turn to environmental factors. The slowdown of cognitive activities and performances in seniors is not inevitably accompanied by a decrease in intellectual capacity, low sensory acuity, or slowing psychomotor skills. Other factors should be considered--such as health status, limitations, anxiety, lack of interest, motivation and attitudes. The loss of cognitive abilities and the prevalence of mild cognitive impairment increase with age and are a growing concern, especially among seniors who drive cars. However, we still lack specific evidence based on tests and criteria--in particular, on psychological and cognitive domains--to assess senior drivers actually at risk. It is important to establish a base of evidence to allow objective risk determination. The safest senior drivers should continue driving for as long as possible, thereby contributing to their mental health, independence and quality of life.

A road map to find in 3D printing a new design plasticity for construction e The state of art

Recent years are showing a rapid adoption of digital manufacturing techniques to the construction industry,with a focus on additive manufacturing.Although 3D printing for construction(3DPC)has notably advanced in recent years,publications on the subject are recent and date a growth in 2019,indicating that it is a promising technology as it enables greater efficiency with fair consumption of material,minimization of waste generation,encouraging the construction industrialization and enhancing and accelerating the constructive process.This new building system not only gives an optimization of the building process but provides a new approach to the building design materiality.The direct connection between design and manufacturing allows the reduction in the number of the various construction phases needed.It is opening a new and wide range of options both formal and chromatic in customization,avoiding complex formworks,reducing costs and manufacturing time.The creative process has a strict and direct link with the constructive process,straightening design with its materiality.Cement-based materials lead the way,but new alternatives are being explored to further reduce its carbon footprint.In order to leverage its sustainability and enhance the system capacity,initiatives are being pursued to allow the reduction of the use of PC.Geopolimers are taking the first steps in 3DPC.Construction and Demolition Waste(CDW)materials are used to substitute natural aggregates.Even soil is being explored has a structural and aesthetic material.These research trends are opening a wider range of possibilities for architecture and design,broadening the spectrum of color,texture,and formal variations.The concern about textures and colours is not yet evident in many the structures already printed,opening the opportunity for future research.More can be done in the mixture and formal design of this building system,“discovering”other raw materials in others waste.This article aims to make a critical review of technologies,materials and methodologies to support the development of new sustainable materials to be used as a plastic element in the printed structure.A roadmap of 3D printing for construction is presented,and an approach on mix design,properties in the fresh and hardened state,highlighting the possibilities for obtaining alternative materials are pointed.With this review possible directions are presented to find solutions to enhance the sustainability of this system discovering“new”materiality for architecture and design.

Evaluation of bearing, gears and gearboxes performance with different wind turbine gear oils

The oil viscosity specification for wind turbine gear oils is ISO VG 320,although there are quite different viscosity indexes oils for that viscosity specification.This work evaluates the behaviour of different base oil formulations,since polyalphaolefin(PAO),mineral,ester and polyalkeleneglycol(PAG)that withstand quite different viscosity indexes.The oils evaluation was done in rolling bearing tests and gear tests.Their behaviour was compared for operating conditions in the range observable in a wind turbine gearbox.The experimental results showed considerable differences between the different oils and it was observed that depending on the contact type the relative behaviour of the lubricants would change,i.e.,the best lubricant for the rolling bearing would not imply the best result on the gear tests.The gear geometry is also very important toward the transmission efficiency,once using a low loss gear concept a decrease of up to 25%in torque loss could be achieved.Numerical models were implemented with the purpose of performing a better simulation of the mechanical system and also to obtain the friction coefficient promoted by the tested oils.

A novel color image encryption algorithm based on a fractional-order discrete chaotic neural network and DNA sequence operations

A novel color image encryption algorithm based on dynamic deoxyribonucleic acid(DNA)encoding and chaos is presented.A three-neuron fractional-order discrete Hopfield neural network(FODHNN)is employed as a pseudo-random chaotic sequence generator.Its initial value is obtained with the secret key generated by a fiveparameter external key and a hash code of the plain image.The external key includes both the FODHNN discrete step size and order.The hash is computed with the SHA-2 function.This ensures a large secret key space and improves the algorithm sensitivity to the plain image.Furthermore,a new three-dimensional projection confusion method is proposed to scramble the pixels among red,green,and blue color components.DNA encoding and diffusion are used to diffuse the image information.Pseudo-random sequences generated by FODHNN are employed to determine the encoding rules for each pixel and to ensure the diversity of the encoding methods.Finally,confusion II and XOR are used to ensure the security of the encryption.Experimental results and the security analysis show that the proposed algorithm has better performance than those reported in the literature and can resist typical attacks.

Modeling of Fluidized Bed Gasification:Assessment of Zero-dimensional and CFD Approaches

In modeling fluidized bed gasification experiments,equilibrium and CFD models are valuable options.The existence of multi-dimensional effects inside the reactor vessel due to the kinetics of the process and the fluid dynamics phenomena could result in deviation from the zero-dimensional assumption.Complex models integrating kinetics and hydrodynamics are being developed by using a computer fluid dynamics(CFD)approach.The objective of this investigation is to assess and compare the adequacy of zero-dimensional and CFD approaches in modeling fluidized bed gasification regarding a semi-industrial scale(numerical results are validated under experimental runs).Results show that the zero-dimensional model based on the approach of dual stage equilibrium performs reasonably well in adequately predicting the product gas composition at different operating conditions and for different feedstocks,although with quantitative discrepancy.Furthermore,the discrepancy depends on the oxygen content of the oxidation agent and on the steam-to biomass ratio decreasing when these parameters increased.CFD models provide deeper information being able to estimate the syngas composition or other operating parameter at any point of space and time.Despite of some quantitative discrepancy,the zero-dimensional modeling approach is deemed satisfactory from the viewpoint of the determining design conditions simulation.

Prediction of Forming Limit Diagrams for Materials with HCP Structure

The forming limit diagram（FLD） is an important tool to be used when characterizing the formability of metallic sheets used in metal forming processes. Experimental measurement and determination of the FLD is timeconsuming and therefore the analytical prediction based on theory of plasticity and instability criteria allows a direct and efficient methodology to obtain critical values at different loading paths, thus carrying significant practical importance.However, the accuracy of the plastic instability prediction is strongly dependent on the choice of the material constitutive model [1–3]. Particularly for materials with hexagonal close packed（HCP） crystallographic structure, they have a very limited number of active slip systems at room temperature and demonstrate a strong asymmetry between yielding in tension and compression [4, 5]. Not only the magnitude of the yield locus changes, but also the shape of the yield surface is evolving during the plastic deformation [4]. Conventional phenomenological constitutive models of plasticity fail to capture this unconventional mechanical behavior [4, 6]. Cazacu and Plunkett [6] have proposed generic yield criteria, by using the transformed principal stress, to account for the initial plastic anisotropy and strength differential（SD） effect simultaneously. In this contribution, a generic FLD MATLAB script was developed based on Marciniak–Kuczynski analytical theory and applied to predict the localized necking. The influence of asymmetrical effect on the FLD was evaluated. Several yield functions such as von Mises, Hill, Barlat89, and Cazacu06 were incorporated into analysis. The paper also presents and discusses the influence of different hardening laws on the formability of materials with HCP crystal structures. The findings indicate that the plastic instability theory coupled with Cazacu model can adequately predict the onset of localized necking for HCP materials under different strain paths.

TRANSIENT ANALYSIS OF COMPOSITE PLATES BY A LOCAL RADIAL BASIS FUNCTIONS-FINITE DIFFERENCE TECHIQUE

The use of local numerical schemes,such as finite differences produces much better conditioned matrices than global collocation radial basis functions methods.However,finite differ-ence schemes are limited to special grids.For scattered points,a combination of finite differences and radial basis functions would be a possible solution.In this paper,we use a higher-order shear deformation plate theory and a radial basis function-finite difference technique for predicting the transient behavior of thin and thick composite plates.Through numerical experiments on beams and composite plates,the accuracy and efficiency of this collocation technique is demonstrated.