Open holes in composite laminates with finite dimensions: structural assessment by analytical methods

Open circular holes are an important design feature, for instance in bolted joint connections. However, stress concentrations arise whose magnitude depends on the material anisotropy and on the defect size relative to the outer finite plate dimensions. To design both safe and light-weight optimal structures, precise means for the assessment are crucial. These can be based on analytical methods providing efficient computation. For this purpose, the focus of the present paper is to provide a comprehensive stress and failure analysis framework based on analytical methods, which is also suitable for use in industry contexts. The stress field for the orthotropic finite-width open-hole problem under uniform tension is derived using the complex potential method. The results are eventually validated against Finite-Element analyses revealing excellent agreement. Then, a failure analysis to predict brittle crack initiation is conducted by means of the Theory of Critical Distances and Finite Fracture Mechanics. These failure concepts of different modelling complexity are compared to each other and validated against experimental data. The size effect is captured, and in this context, the influence of finite width on the effective failure load reduction is investigated.

Self-tuition as an essential design feature of the brain

We are curious by nature, particularly when young. Evolution has endowed our brain with an inbuilt obligation to educate itself. In this perspectives article, we posit that self-tuition is an evolved principle of vertebrate brain design that is reflected in its basic architecture and critical for its normal development. Self-tuition involves coordination between functionally distinct components of the brain, with one set of areas motivating exploration that leads to the experiences that train another set. We review key hypothalamic and telencephalic structures involved in this interplay, including their anatomical connections and placement within the segmental architecture of conserved forebrain circuits. We discuss the nature of educative behaviours motivated by the hypothalamus, innate stimulus biases, the relationship to survival in early life, and mechanisms by which telencephalic areas gradually accumulate knowledge. We argue that this aspect of brain function is of paramount importance for systems neuroscience, as it confers neural specialization and allows animals to attain far more sophisticated behaviours than would be possible through genetic mechanisms alone. Self-tuition is of particular importance in humans and other primates, whose large brains and complex social cognition rely critically on experience-based learning during a protracted childhood period. This article is part of the theme issue ‘Systems neuroscience through the lens of evolutionary theory’.

Development of a method for designing specialized machinery based on a hinge tractor

The method of designing frames of special machines for road construction and public utilities is considered, which allows you to design special machines with a given level of reliability and durability. The technique allows using modern computer modeling systems to carry out constructive refinement of the base tractor frame using experimental and mathematical modeling data. Using the design feature of tractors of the T–150K family, namely the presence of an articulated joint, it is possible, using a modular principle, to quickly design various machines for various industries. However, in order to design reliable machines, one must have a methodology for designing such machines. There is currently no such technique. When designing special machines, designers perform calculations only for working equipment. But as practice shows, the critical elements of the machine in this case, the support of the vertical hinge of the tractor frame during the operation of the pressurized machine (wheeled bulldozer and front loader), experience shock loads that lead to the destruction of the frame of the base tractor. The purpose of the article is to develop a methodology for designing a complex of road–building machines on the basis of mass–produced tractors with an articulated frame produced by public limited company "KhTZ".

A systematic reviewof experimental researchin audiovisual translation 1992–2020

This study systematically reviewed 61 experimental studies on audiovisual translation (AVT), published in academic journals between 1992 and 2020. The review examined five aspects of these studies: publication trends, research scopes, research designs, statistical procedures, and reporting practices. Major findings include: (a) there has been a slight concentration of publication outlets for experimental AVT research; (b) the focal studies could be categorized into three themes (product, process, and pedagogy), with the product theme being the most popular and subtitling the dominant AVT modality; (c) the inclusion of a comparison group was the most common design feature, and questionnaires and tests were the most popular research instruments; (d) inferential statistical analysis was favored over descriptive statistical analysis; (e) data normality information and effect sizes were not regularly reported. Based on the systematic review, suggestions are made for the future development of experimental AVT research.

Inspection Robotic UGV Platform and the Procedure for an Acoustic Signal-Based Fault Detection in Belt Conveyor Idler

Belt conveyors are commonly used for the transportation of bulk materials. The most characteristic design feature is the fact that thousands of idlers are supporting the moving belt. One of the critical elements of the idler is the rolling element bearing, which requires monitoring and diagnostics to prevent potential failure. Due to the number of idlers to be monitored, the size of the conveyor, and the risk of accident when dealing with rotating elements and moving belts, monitoring of all idlers (i.e., using vibration sensors) is impractical regarding scale and connectivity. Hence, an inspection robot is proposed to capture acoustic signals instead of vibrations commonly used in condition monitoring. Then, signal processing techniques are used for signal pre-processing and analysis to check the condition of the idler. It has been found that even if the damage signature is identifiable in the captured signal, it is hard to automatically detect the fault in some cases due to sound disturbances caused by contact of the belt joint and idler coating. Classical techniques based on impulsiveness may fail in such a case, moreover, they indicate damage even if idlers are in good condition. The application of the inspection robot can “replace” the classical measurement done by maintenance staff, which can improve the safety during the inspection. In this paper, the authors show that damage detection in bearings installed in belt conveyor idlers using acoustic signals is possible, even in the presence of a significant amount of background noise. Influence of the sound disturbance due to the belt joint can be minimized by appropriate signal processing methods.

Development of the design and justification of the parameters of the guide rapier of the weaving machine

The article describes the design feature and the principle of operation of the recommended pattern of the weaving rapier guide. On the basis of theoretical studies, graphical dependencies of the parameters of the guide roller were adjusted, the system parameters were recommended by analyzes.

Should RECOVERY have used Response Adaptive Randomization? Evidence from a simulation study

Background The Randomised Evaluation of COVID-19 Therapy (RECOVERY) trial is aimed at addressing the urgent need to find effective treatments for patients hospitalised with suspected or confirmed COVID-19. The trial has had many successes, including discovering that dexamethasone is effective at reducing COVID-19 mortality, the first treatment to reach this milestone in a randomised controlled trial. Despite this, it continues to use standard or `fixed’ randomization (FR) to allocate patients to treatments. We assessed the impact of implementing response adaptive randomization (RAR) within RECOVERY using an array of performance measures, to learn if it could be beneficial going forward. This design feature has recently been implemented within the REMAP-CAP trial.Methods Trial data was simulated to closely match the data for patients allocated to either standard care or dexamethasone in the RECOVERY trial from March-June 2020, representing two out of five arms tested throughout this period. Two forms of FR and two forms of RAR were tested. Randomization strategies were performed at the whole trial level as well as within three pre-specified patient subgroups defined by patients’ respiratory support level.ResultsRAR strategies led to more patients being given dexamethasone and a lower mortality rate in the trial. Subgroup specific RAR reduced mortality rates even further. RAR did not induce any meaningful bias in treatment effect estimates, but reduced statistical power compared to FR, with subgroup level adaptive randomizations exhibiting the largest power reduction.ConclusionsUsing RAR within RECOVERY could have resulted in fewer deaths in the trial. However, a larger trial would have been needed to attain the same study power. This could potentially have prolonged the time to full approval of the drug, unless RAR itself led to an increased recruitment rate. Deciding how to balance the needs of patients within a trial and future patients who have yet to fall ill is an important ethical question of our time. RAR deserves to be considered as a design feature in future trials of COVID-19 and other diseases.

Dynamic Instability Analysis of a Double-Blade Centrifugal Pump

The flow instability of a double-blade centrifugal pump is more serious due to its special design feature with two blades and large flow passages. The dynamic instabilities and pressure pulsations can affect the pump performance and operating lifetime. In the present study, a numerical investigation of unsteady flow and time variation of pressure within a complete double-blade centrifugal pump was carried out. The time domain and frequency domain of pressure pulsations were extracted at 16 monitoring locations covering the important regions to analyze the internal flow instabilities of the pump model. The frequency spectra of pressure pulsations were decomposed into Strouhal number dependent functions. This led to the conclusion that the blade passing frequency (BPF) related vibrations are exclusively flow-induced. Large vortices were observed in the flow passages of the pump at low flow rate. It is noted that high vorticity magnitude occurred in the vicinities of the blade trailing edge and tongue of the volute, due to the rotor-stator interaction between impeller and volute.

Improving Quality of Care in Virtual Visits: Heuristic Evaluations of the User Interface in Telehealth

The COVID-19 pandemic has expedited the growing rate of reliance on telehealth. Beyond the benefits of telehealth for patients and healthcare providers during atypical circumstances, the changes prompted by the pandemic have possibly altered the position of telehealth to the point that virtual communication will become the new normal. Therefore, the importance of designing an interface to facilitate user interaction with the system and consequently with one another is of utmost importance. Building on Nielsen’s usability heuristics and mapping them to the six aspects of quality of care introduced by the Institute of Medicine, we identify the design features that have the highest impact on the quality of care. Our analysis shows that error prevention and recovery is the most influential design feature, followed by help and documentation, visibility of the system, match between the system and the real world, flexibility and efficiency of use, and user control and freedom.