Elastomer-based visuotactile sensor for normality of robotic manufacturing systems

Modern aircrafts require the assembly of thousands of components with high accuracy and reliability. The normality of drilled holes is a critical geometrical tolerance that is required to be achieved in order to realize an efficient assembly process. Failure to achieve the required tolerance leads to structures prone to fatigue problems and assembly errors. Elastomer-based tactile sensors have been used to support robots in acquiring useful physical interaction information with the environments. However, current tactile sensors have not yet been developed to support robotic machining in achieving the tight tolerances of aerospace structures. In this paper, a novel elastomer-based tactile sensor was developed for cobot machining. Three commercial silicon-based elastomer materials were characterised using mechanical testing in order to select a material with the best deformability. A Finite element model was developed to simulate the deformation of the tactile sensor upon interacting with surfaces with different normalities. Additive manufacturing was employed to fabricate the tactile sensor mould, which was chemically etched to improve the surface quality. The tactile sensor was obtained by directly casting and curing the optimum elastomer material onto the additively manufactured mould. A machine learning approach was used to train the simulated and experimental data obtained from the sensor. The capability of the developed vision tactile sensor was evaluated using real-world experiments with various inclination angles, and achieved a mean perpendicularity tolerance of 0.34°. The developed sensor opens a new perspective on low-cost precision cobot machining

The non-zero divisor graph of ring of integers modulo six and the hamiltonian quaternion over integers modulo two

The study of graph theory was introduced and widely researched since many practical problems can be represented by graphs. A non-zero divisor graph is a graph in which its set of vertices is the non-zero elements of the ring and the vertices x and y are adjacent if and only if xy ≠ 0. In this study, we introduced the non-zero divisor graphs of some finite commutative rings in specific the ring of in tegers modulo 6, 6 and ring of Hamiltonian quaternion, (2). First, the non-zero divisors of the commutative rings are found. Then, the non-zero divisor graphs are constructed. Finally, some properties of the graph, including the chromatic number, clique number, girth and the diameter are obtained

Multiple characterization of some glassy-alloys as photon and neutron shields: In-silico Monte Carlo investigation

In the present work, the nuclear radiation shielding proficiency of eight glassy alloys (Gd25RE25Co25Al25 (RE = Tb, Dy and Ho)) containing different amounts of rare earth elements was investigated with MCNPX simulation codes. Mass attenuation coefficients (μ/ρ) of the glassy alloys were simulated in the energy interval of 0.2-20 MeV by exploiting MCNPX codes, and the generated data were found to match with theoretical WinXCOM results. Next, other crucial photon attenuation parameters, effective atomic number (Zeff), Half Value Layer (HVL), and Mean Free Path (MFP), were gotten out using μ/ρ values. It was seen that Er20Tm20 and Er20Tb20 samples replaced with Er by Gd had the highest Zeff and μ/ρ values, whereas HVL and MFP values were the smallest among the other glassy alloys. Geometric progression (GP) procedure was enjoyed to achieve the exposure and energy absorption buildup factors (EBF and EABF) for the glassy alloys proposed. EABFs and EBFs took the largest and lowest values for Gd25Tb25 and Er20Tm20, respectively, to the other samples. Furthermore, the glassy alloys' neutron reduction abilities were estimated by acquiring fast neutron removal cross-sections (∑R). It was noticed that the ∑R values of the glassy alloys are increased with the rising sample density and seen to be comparable to ∑R values of water and ordinary concrete. The results obtained from this study are important in that they show that glassy alloys can be used as radiation shielding. © 2021 The Author(s). Published by IOP Publishing Ltd

Influence of basal plane domains in the tribological behavior of graphites

ABSTRACT Many dynamic engineering systems have interferences and interactions that causes wear under friction effect. Carbonaceous materials, such as polycrystalline graphites, are of great interest in engineering systems due to their inherent lubricant properties and their versatility as a material for applications in the areas of mechanics, transportation, energy systems and sensitive technologies. In this work the tribological behavior of three identical pairs, pin-on-disc, of commercial polycrystalline graphites were evaluated, in a controlled environment at 20 °C and 50 % RH. Results of tribological behavior were correlated considering the prevalence of basal plane, identified by polarized light optical microscopy, as a function of the tribological behavior, measured by tests with pin on disc tribometer. The results showed that the coefficient of friction behavior is directly related to the basal plane mosaic domain and the extension of the damage generated on this plane due to the contact between the tribological pair. The materials studied presented an increase in the friction coefficient values, 0,10; 0;13 and 0,23 with increasing area of the basal plane mosaic domain, respectively 55; 64 and 81% respectively

ACO2 homozygous missense mutation associated with complicated Hereditary spastic paraplegia

Objective: To identify the clinical characteristics and genetic etiology of a family affected with hereditary spastic paraplegia (HSP). Methods: Clinical, genetic, and functional analyses involving genome-wide linkage coupled to whole-exome sequencing in a consanguineous family with complicated HSP. Results: A homozygous missense mutation was identified in the ACO2 gene (c.1240T>G p.Phe414Val) that segregated with HSP complicated by intellectual disability and microcephaly. Lymphoblastoid cell lines of homozygous carrier patients revealed significantly decreased activity of the mitochondrial aconitase enzyme and defective mitochondrial respiration. ACO2 encodes mitochondrial aconitase, an essential enzyme in the Krebs cycle. Recessive mutations in this gene have been previously associated with cerebellar ataxia. Conclusions: Our findings nominate ACO2 as a disease-causing gene for autosomal recessive complicated HSP and provide further support for the central role of mitochondrial defects in the pathogenesis of HSP

Occupational therapy in HomEcare Re-ablement Services (OTHERS): study protocol for a randomized controlled trial

Background: Homecare re-ablement services have been developed by local authorities in England in response to the government agenda for health and social care. These services aim to optimize users’ independence and ability to cope at home, and reduce the need for ongoing health and social care services. However, there is currently limited evidence and guidance regarding the optimum configuration and delivery of re-ablement services. In particular, the impact of occupational therapy input on service user outcomes has been highlighted as a specific research priority. Methods/Design: This feasibility randomized controlled trial (RCT) will recruit 50 people from one local authority led homecare re-ablement service in England. Those who provide informed consent will be randomized to receive either usual homecare re-ablement (without routine occupational therapy input) or usual homecare re-ablement plus an enhanced program targeted at activities of daily living (ADL), delivered by an occupational therapist. The primary aim of this study is to assess the feasibility of conducting a further, powered study. The participant outcomes assessed will be independence in personal and extended ADL, health and social care-related quality of life, number of care support hours, falls, acute and residential admissions and use of health and social care services. These will be assessed at two weeks, three months and six months post-discharge from the re-ablement service. Discussion: To our knowledge, this is the first RCT of occupational therapy in homecare re-ablement services. The results of this study will lay the foundations for a further powered study. The findings will be relevant to researchers, clinicians, commissioners and users of adult social care services

Defining criteria for disease activity states in systemic juvenile idiopathic arthritis based on the systemic Juvenile Arthritis Disease Activity Score

Objective To develop and validate cutoff values in the systemic Juvenile Arthritis Disease Activity Score 10 (sJADAS10) that distinguish the states of inactive disease (ID), minimal disease activity (MiDA), moderate disease activity (MoDA), and high disease activity (HDA) in children with systemic juvenile idiopathic arthritis (sJIA), based on subjective disease state assessment by the treating pediatric rheumatologist. Methods The cutoffs definition cohort was composed of 400 patients enrolled at 30 pediatric rheumatology centers in 11 countries. Using the subjective physician rating as an external criterion, 6 methods were applied to identify the cutoffs: mapping, calculation of percentiles of cumulative score distribution, Youden index, 90% specificity, maximum agreement, and ROC curve analysis. Sixty percent of the patients were assigned to the definition cohort and 40% to the validation cohort. Cutoff validation was conducted by assessing discriminative ability. Results The sJADAS10 cutoffs that separated ID from MiDA, MiDA from MoDA, and MoDA from HDA were ≤ 2.9, ≤ 10, and > 20.6. The cutoffs discriminated strongly among different levels of pain, between patients with or without morning stiffness, and between patients whose parents judged their disease status as remission or persistent activity/flare or were satisfied or not satisfied with current illness outcome. Conclusion The sJADAS cutoffs revealed good metrologic properties in both definition and validation cohorts, and are therefore suitable for use in clinical trials and routine practice

Targeted sequencing of 351 candidate genes for epileptic encephalopathy in a large cohort of patients

Many genes are candidates for involvement in epileptic encephalopathy (EE) because one or a few possibly pathogenic variants have been found in patients, but insufficient genetic or functional evidence exists for a definite annotation