Cold-Formed Steel Sections with Web Openings Subjected to Web Crippling under Two-Flange Loading Conditions — Part I : Tests and Finite Element Analysis

The results of 82 web crippling tests are presented, with 20 tests conducted on channel sections without web openings and 62 tests conducted on channel sections with web openings. The tests consider both end-two-flange and interior-two-flange loading conditions. In the case of the tests with web openings, the hole was located directly under the concentrated load. The concentrated load was applied through bearing plates; the effect of different bearing lengths is investigated. In addition, the cases of both flanges fastened and unfastened to the support were considered. A non-linear elasto-plastic finite element model is described, and the results compared against the laboratory test results; a good agreement was obtained in terms of both strength and failure modes

Cold-formed steel sections with web openings subjected to web crippling under two-flange loading conditions — Part II : Parametric study and proposed design equations

A parametric study of cold-formed steel sections with web openings subjected to web crippling was undertaken using finite element analysis, to investigate the effects of web holes and cross-section sizes on the web crippling strengths of channel sections subjected to web crippling under both interior-two-flange (ITF) and end-two-flange (ETF) loading conditions. In both loading conditions, the hole was centred beneath the bearing plate. It was demonstrated that the main factors influencing the web crippling strength are the ratio of the hole depth to the flat depth of the web, and the ratio of the length of bearing plates to the flat depth of the web. In this paper, design recommendations in the form of web crippling strength reduction factors are proposed, that are conservative to both the experimental and finite element results

The effects of web opening on web crippling strength of cold-formed steel channels under interior-two-flange loading condition

Cold-formed steel sections are increasingly used in residential and commercial construction as both the primary as well as the secondary framing members. Web crippling at points of concentrated load or reaction is well known to be a significant problem, particularly in thin walled beams. To improve the buildability of buildings composed of cold-formed steel channel-sections, openings in the web are often required, for ease of installation of electrical or plumbing services. In this paper, a combination of experimental tests and non-linear elasto-plastic finite element analyses are used to investigate the effect of such holes on web crippling under the interior-two-flange (ITF) loading condition. In the case of the tests with web openings, the web holes located at the mid-depth of the webs. A non-linear elasto-plastic finite element model is described, and the results compared against the laboratory test results; a good agreement was obtained in terms of both strength and failure modes

Kalman tracking of linear predictor and harmonic noise models for noisy speech enhancement

This paper presents a speech enhancement method based on the tracking and denoising of the formants of a linear prediction (LP) model of the spectral envelope of speech and the parameters of a harmonic noise model (HNM) of its excitation. The main advantages of tracking and denoising the prominent energy contours of speech are the efficient use of the spectral and temporal structures of successive speech frames and a mitigation of processing artefact known as the ‘musical noise’ or ‘musical tones’.The formant-tracking linear prediction (FTLP) model estimation consists of three stages: (a) speech pre-cleaning based on a spectral amplitude estimation, (b) formant-tracking across successive speech frames using the Viterbi method, and (c) Kalman filtering of the formant trajectories across successive speech frames.The HNM parameters for the excitation signal comprise; voiced/unvoiced decision, the fundamental frequency, the harmonics’ amplitudes and the variance of the noise component of excitation. A frequency-domain pitch extraction method is proposed that searches for the peak signal to noise ratios (SNRs) at the harmonics. For each speech frame several pitch candidates are calculated. An estimate of the pitch trajectory across successive frames is obtained using a Viterbi decoder. The trajectories of the noisy excitation harmonics across successive speech frames are modeled and denoised using Kalman filters.The proposed method is used to deconstruct noisy speech, de-noise its model parameters and then reconstitute speech from its cleaned parts. Experimental evaluations show the performance gains of the formant tracking, pitch extraction and noise reduction stages

Evolving Ensemble Models for Image Segmentation Using Enhanced Particle Swarm Optimization

In this paper, we propose particle swarm optimization (PSO)-enhanced ensemble deep neural networks and hybrid clustering models for skin lesion segmentation. A PSO variant is proposed, which embeds diverse search actions including simulated annealing, levy flight, helix behavior, modified PSO, and differential evolution operations with spiral search coefficients. These search actions work in a cascade manner to not only equip each individual with different search operations throughout the search process but also assign distinctive search actions to different particles simultaneously in every single iteration. The proposed PSO variant is used to optimize the learning hyper-parameters of convolutional neural networks (CNNs) and the cluster centroids of classical Fuzzy C-Means clustering respectively to overcome performance barriers. Ensemble deep networks and hybrid clustering models are subsequently constructed based on the optimized CNN and hybrid clustering segmenters for lesion segmentation. We evaluate the proposed ensemble models using three skin lesion databases, i.e., PH2, ISIC 2017, and Dermofit Image Library, and a blood cancer data set, i.e., ALL-IDB2. The empirical results indicate that our models outperform other hybrid ensemble clustering models combined with advanced PSO variants, as well as state-of-the-art deep networks in the literature for diverse challenging image segmentation tasks

SNP identification of Africanized honey bees

Pubertal growth results from increased sex steroid and growth hormone (GH) secretion. Estrogens appear to play an important role in the regulation of pubertal growth in both girls and boys. In girls, however, estrogens cannot be the only sex steroids responsible for pubertal growth, as exogenous estrogens do not initiate a complete growth spurt. We therefore investigated the levels of the different sex steroids and GH, and related them to pubertal growth. In addition, we studied the process of bone maturation and mineralization during this period. Levels of both estrogens and androgens were found to increase at the start of the female pubertal growth spurt, and it was demonstrated that height velocity is related to levels of GH, estradiol and androstenedione, but not dehydroepiandrosterone sulfate. In boys, GH, testosterone and estradiol increased at the time of peak height velocity. Bone mineralization increased as puberty began, and was associated with the increase in height velocity. Osteocalcin, a marker of bone formation, declined when height velocity decreased, although bone maturation progressed at a steady rate. We conclude, therefore, that in girls, the concerted actions of estradiol, GH and androstenedione play a role in the pubertal growth spurt, whereas in boys this role is fulfilled by testosterone, GH and estradiol. During puberty, an advanced rate of bone maturation with respect to cross-sectional standards is a physiological phenomenon

Advancing loneliness and social isolation as global health challenges: taking three priority actions

Loneliness and social isolation have been identified as critical global health issues in the aftermath of the coronavirus disease 2019 (COVID-19) crisis. While there is robust scientific evidence demonstrating the impact of loneliness and social isolation on health outcomes and mortality, there are fundamental issues to resolve so that health authorities, decision makers, and practitioners worldwide are informed and aligned with the latest evidence. Three priority actions are posited to achieve a wider and more substantial impact on loneliness and social isolation. They are 1) strengthening the evidence base; 2) adopting a whole-of-systems approach; 3) developing policy support for governments worldwide. These priority actions are essential to reduce the pervasive impact of loneliness and social isolation as social determinants of health

Compact and high-quality gamma-ray source applied to 10 μm-range resolution radiography

International audienceGamma-ray beams with optimal and tuneable size, temperature, and dose are of great interest for a large variety of applications. These photons can be produced by the conversion of energetic electrons through the bremsstrahlung process in a dense material. This work presents the experimental demonstration of 30 μm resolution radiography of dense objects using an optimized gamma-ray source, produced with a high-quality electron beam delivered by a compact laser-plasma accelerator

Design of cold-formed stainless steel lipped channel sections with web openings subjected to web crippling under end-one-flange loading condition

This article presents a numerical investigation on the web crippling strength of cold-formed stainless steel lipped channel sections with circular web openings under end-one-flange loading condition. In order to take into account the influence of the circular web openings, a parametric study involving 1992 finite element analyses was performed, covering duplex EN1.4462, austenitic EN1.4404 and ferritic EN1.4003 stainless steel grades; from the results of the parametric study, strength reduction factor equations are proposed. The web crippling strengths predicted by the reduction factor equations are first compared to the strengths calculated using the equations recently proposed for cold-formed carbon steel lipped channel sections. It is demonstrated that the strength reduction factor equations proposed for cold-formed carbon steel are unconservative for the stainless steel grades by up to 7%. Unified strength reduction factor equations are then proposed that can be applied to all three stainless steel grades