Tapered laminate designs for new non-crimp fabric architectures

Non-Crimp Fabric (NCF) materials are now available in a range of areal weights and layer architectures, including 0/45, 0/−45, 45/−45 and 0/90, which correspond to the standard ply orientations employed in traditional UD material lay-ups. The benefit of NCF material is generally associated with increased deposition rate, but this advantage may be offset by reduced design freedoms when a specific form of mechanical coupling behaviour is required, layer terminations must be introduced and/or thermal warping distortion eliminated. This article investigates the extent to which new NCF architectures can be tailored to achieve warp free tapered laminates with mechanical Extension-Shearing Bending-Twisting coupling, by single axis (longitudinal) deposition of all ply angles; thus avoiding ply discontinuities that may be introduce in large component manufacture. Lamination parameter design spaces are used to demonstrate the extent of the feasible solutions both before and after applying a laminate tapering scheme

Effect of bending-twisting coupling on the compression and shear buckling strength of infinitely long plates

This article describes the development of closed form polynomial equations for compression and shear buckling to assess the effect of Bending-Twisting coupling on infinitely long laminated plates with simply supported edges. The equations are used to generate contour maps, representing non-dimensional buckling factors, which are superimposed on the lamination parameter design spaces for laminates with standard ply orientations. The contour maps are applicable to two recently developed databases containing symmetric and non-symmetric laminates with either Bending-Twisting or Extension-Shearing Bending-Twisting coupling. The contour maps provide new insights into buckling performance improvements that are non-intuitive and facilitate comparison between hypothetical and practical designs. The databases are illustrated through point clouds of lamination parameter coordinates, which demonstrate the effect of applying common design heuristics, including ply angle, ply percentage and ply contiguity constraints

On extension-shearing bending-twisting coupled laminates

This article presents details of the development of a special class of laminate, possessing Extension-Shearing Bending-Twisting coupling, necessary for optimised passive-adaptive flexible wing-box structures. The possibility of achieving a measurable drag reduction in cruise flight, without the cost or reliability issues associated with active control mechanisms, is of significant interest for achieving increased fuel burn efficiency, and meeting associated emissions targets. The introduction of passive Bending-Twisting coupling at the wing-box level has been previously demonstrated through laminate level tailoring with Extension-Shearing coupling only, but the limited design space and the possibility for ply terminations (to produce tapered thickness) effectively rule out this special class of laminate for practical construction. The study is now broadened to consider laminates with Extension-Shearing and Bending-Twisting coupling, beyond the less well-known un-balanced and symmetric design rule or indeed balanced and symmetric designs with off-axis alignment. Results reveal a vast laminate design space with Extension-Shearing coupling that can be maximised without the unfavourable strength characteristics associated with off-axis alignment. Results also reveal that shear buckling strength can be maximised through Bending-Twisting coupling when load reversal is not a design constraint

Effect of Design Heuristics on the Compression and Shear Buckling Performance of Infinitely Long Plates With Bending-Twisting Coupling

This article investigates the effect of design heuristics, including ply percentages and ply contiguity constraints, on the compression and shear buckling performance of Bending-Twisting coupled infinitely long laminated plates with simply supported edges. The buckling solutions are presented as contour maps, representing non-dimensional buckling factors, which are superimposed on the lamination parameter design spaces for laminates with standard ply orientations. The applicability of the results extends beyond the current certification envelope, comprising symmetric laminate configurations. Indeed, the contour maps are applicable to two recently developed databases containing non-symmetric and symmetric laminates with either Bending-Twisting or Extension-Shearing Bending-Twisting coupling. The contour maps provide insights into buckling performance improvements that are non-intuitive and facilitate comparison between hypothetical and practical designs. The databases are illustrated through point clouds of lamination parameter coordinates, which demonstrate the effect of applying design heuristics

Molar-incisor enamel hypomineralization cross-sectional prevalence evaluation in oral-breathing allergic children

Objetivo: Hipomineralização incisivo-molar (HIM) é um distúrbio de desenvolvimento dentário altamente prevalente devi­do à maturação interrompida do ameloblasto. Esta condição afeta até 44% das crianças ao redor do mundo e várias condições sistêmicas têm sido associadas à HIM, incluindo a respiração oral. E importante mostrar que HIM tem etiologia multifatorial e está associada com crianças alérgicas com respiração bucal. Métodos: Para avaliar a prevalência da HIM em crianças com SRBI com resposta alérgica positiva e negativa para testes de escarificação, uma avaliação transversal quantitativa e qualitativa foi realizada em 23 crianças com respiração oral e 25 irmãos com idade/sexo correspondentes. Defeitos de esmalte foram classificados de acordo com o índice de defeitos de esmalte da FDI. Teste t de Student foi aplicado para verificar a relevância dos dados. Resultados: A prevalência de HIM mostrou diferenças estatísticas significativas na comparação entre molares, independentemente de idade individual (p = 0,01513474). Crianças com SRBI menores de 5 anos apresentaram maior prevalência estatística de HIM (p = 0,00594). Crianças com SRBI que obtiveram reações positivas para os testes de escarificação apresentaram maior prevalência de HIM (p = 0,023). Crianças com SRBI apresentaram maior prevalência estatística de opacidade demarcada (p = 0,00012). Conclusões: Crianças com SRBI que obtiveram reações positivas para os testes de escarificação apresentaram maior prevalência de HIM (p = 0,023), indicando que crianças alérgicas com respiração oral tiveram maior prevalência de HIM. Nossos resultados corroboram nossa hipótese anterior que crianças com SRBI demonstram maior prevalência de HIM em comparação com seus irmãos, com significância estatística (p = 0,01513474). Investigações com amostras popu­lacionais maiores podem reforçar e confirmar a exatidão dos nossos resultados.Objective: Molar-incisor hypomineralization (MIH) is a highly prevalent dental development disturbance caused by dis­rupted ameloblast maturation. This condition affects up to 44% of children around the world and several systemic con­ditions have been associated with MIH, including Mouth-Breathing. It is important to show that MIH has multifacto­rial etiology and is associated with allergic mouth-breathing children. Methods: To evaluate MIH prevalence in MBCS children with positive and negative allergic response to the skin prick test, a cross-sectional quantitative and qualitative comparative assessment was conducted in 23 mouth-breathing children and 25 sex/age-matched siblings. Enamel defects were classified by the modified rate of FDI Development Defects of Enamel. Statistical Student’s t tests were applied to ve­rify the relevance of the data. Results: MIH prevalence showed significant statistical differences in the comparison betwe­en molars, independently of individual age (p = 0.01513474). MBCS children under 5 years old had higher statistical preva­lence of MIH (p = 0.00594). MBCS children with positive skin reactions to the prick test had higher prevalence of MIH (p = 0,023). MBCS children had statistically significant higher prevalence of demarcated opacity (p = 0.00012). Conclusions: Finally, MBCS children with positive skin reactions to the prick test had higher prevalence of MIH (p = 0,023), indicating that mouth-breathing allergy-responsive children had higher MIH prevalence. Our results corroborate our previous hypo­thesis that MBCS children have increased MIH prevalence in comparison to their siblings, with statistical significance (p = 0.01513474). Further investigations with larger samples may enhance and confirm the accuracy of our results

Un motor de inducción

Este trabajo es una propuesta destinada a docentes y estudiantes de Física, invitándolos a la construcción de un modelo experimental de motor que funciona por la interacción de un campo magnético rotante y las corrientes inducidas por éste en un cuerpo conductor, en  forma similar que ciertos modelos de tipo industrial.</p

Coherent Production of Pairs of Parabosons of Order 2

A parameter-free statistical model is used to study multiplicity signatures for coherent production of charged-pairs of parabosons of order p=2 in comparison with those arising in the case of ordinary bosons, p=1. Two non-negative real parameters arise because "ab" and "ba" are fundamentally distinct pair operators of charge "+1", A-quanta and charge "-1", B-quanta parabosons. In 3D plots of P(q)_m = "The probability of m paraboson charged-pairs and q positive parabosons" versus and , the p=1 curve is found to lie on the relatively narrow 2D p=2 surface.Comment: 25 pages, 16 figures, no macro

Effect of Design Heuristics on the Compression and Shear Buckling Performance of Infinitely Long Plates With Bending-Twisting Coupling

This article investigates the effect of design heuristics, including ply percentages and ply contiguity constraints, on the compression and shear buckling performance of Bending-Twisting coupled infinitely long laminated plates with simply supported edges. The buckling solutions are presented as contour maps, representing non-dimensional buckling factors, which are superimposed on the lamination parameter design spaces for laminates with standard ply orientations. The applicability of the results extends beyond the current certification envelope, comprising symmetric laminate configurations. Indeed, the contour maps are applicable to two recently developed databases containing non-symmetric and symmetric laminates with either Bending-Twisting or Extension-Shearing Bending-Twisting coupling. The contour maps provide insights into buckling performance improvements that are non-intuitive and facilitate comparison between hypothetical and practical designs. The databases are illustrated through point clouds of lamination parameter coordinates, which demonstrate the effect of applying design heuristics

THE EFFECT OF ADVERSE LIFE EVENTS ON HIV SERVICES AMONG FEMALE SEX WORKERS AND OTHER HIGH RISK WOMEN IN MALAWI

In the high HIV-burden country of Malawi, female sex workers (FSW) are one of the populations most affected. HIV services in venue-based outreach settings target FSW, but miss women who engage in similar high-risk behaviors. Furthermore, exposure to adverse life events (ALEs) can affect how and if women utilize these services. This study aimed to compare the access and utilization of HIV services among FSW, women who engage in sex work, but don’t self-identify as FSW (OFSW), and other high risk women (OHRW) and determine if there was an association between ALEs and these outcomes. 1,004 FSW, 213 OFSW, and 130 OHRW were recruited from venues in 15 districts in Malawi using the Priorities for Local AIDS Control Efforts (PLACE) methodology. All participants completed a behavioral interview. Analyses compared the self-reported prevalence of behaviors, access to services, and risk factors between the three groups and associations between exposure to ALEs and the same outcomes using survey-weighted Poisson regression models. Each of the groups had a distinct pattern of usage and access to services. OFSW and FSW were more likely to have bought condoms, accessed condoms for free, and received information from outreach workers compared to OHRW. Ever using a male condom and HIV testing in the last 6 months was greatest among FSW, followed by OFSW and OHRW. Nearly all women knew where to get tested for HIV, but very few used FSW drop-in centers. HIV prevalence was high in all three groups (35% FSW, 20% OFSW, 20% OHRW). Prevalence of any ALE and mean number of ALEs among FSW and OFSW were more than double that of OHRW. Among all women, increasing number of ALEs was associated with increased risk of condomless sex, greater access to HIV prevention services, and, among HIV-positive women, worse self-reported adherence to ART. All women socializing at venues in Malawi should be offered HIV prevention, care and treatment services, regardless of their sex worker status. Prevalence of ALEs is high in many of these women, indicating a need to address mental health effects to reduce the burden of HIV among women in rural Malawi.Doctor of Philosoph