Comportamento experimental de diferentes tipos de conectores metálicos

A realização de estruturas mistas de aço e betão requer o funcionamento conjunto destes dois materiais. A ligação entre eles é conseguida com a utilização de conectores metálicos. Neste âmbito, tem sido realizada uma considerável quantidade de estudos que abordam o comportamento de diversos tipos de conectores metálicos. O desejo de obter um comportamento óptimo com custos mínimos motivou o desenvolvimento de várias soluções. Neste artigo, procura-se descrever o comportamento de diferentes tipos de conectores observado em ensaios experimentais realizados na Universidade do Minho (UM) ou em estreita colaboração da UM com outras entidades. Apresentam-se as vantagens e as desvantagens associadas a cada tipologia de conexão analisada. Para além dos usuais conectores tipo perno, discutem-se os resultados obtidos com conectores do tipo T, tipo Perfobond, tipo Crestbond e ligação por aderência

Difference between the default telecoil (T-Coil) and programmed microphone frequency response in behind-the-ear (BTE) hearing aids

BACKGROUND: A telecoil (t-coil) is essential for hearing aid users when listening on the telephone because using the hearing aid microphone when communicating on the telephone can cause feedback due to telephone handset proximity to the hearing aid microphone. Clinicians may overlook the role of the t-coil due to a primary concern of matching the microphone frequency response to a valid prescriptive target. Little has been published to support the idea that the t-coil frequency response should match the microphone frequency response to provide “seamless” and perhaps optimal performance on the telephone. If the clinical goal were to match both frequency responses, it would be useful to know the relative differences, if any, which currently exist between these two transducers. PURPOSE: The primary purpose of this study was to determine if statistically significant differences were present between the mean output (in dB SPL) of the programmed microphone program and the hearing aid manufacturer’s default t-coil program as a function of discrete test frequencies. In addition, pilot data are presented on the feasibility of measuring the microphone and t-coil frequency response with real-ear measures using a digital speech-weighted noise. RESEARCH DESIGN: A repeated-measures design was utilized for a 2-cc coupler measurement condition. Independent variables were the transducer (microphone; t-coil), and eleven discrete test frequencies (fifteen discrete frequencies in the real-ear pilot condition). STUDY SAMPLE: The study sample was comprised of behind-the-ear (BTE) hearing aids from one manufacturer. Fifty-two hearing aids were measured in a coupler condition, 39 of which were measured in the real-ear pilot condition. Hearing aids were previously programmed and verified using real-ear measures to the NAL-NL1 prescriptive target by a licensed audiologist. DATA COLLECTION AND ANALYSIS: Hearing aid output was measured with a Fonix 7000 hearing aid analyzer (Frye Electronics, Inc.) in a HA-2 2-cc coupler condition using a pure-tone sweep at an input level of 60 dB SPL with the hearing aid in the microphone program and 31.6 mA/M in the t-coil program. A digital speech weighted noise input signal presented at additional input levels was used in the real-ear pilot condition. A mixed model repeated-measures Analysis of Variance (ANOVA) and the Tukey Honestly Significant Difference (HSD) post-hoc test were utilized to determine if significant differences were present in performance across treatment levels. RESULTS: There was no significant difference between mean overall t-coil and microphone output averaged across 11 discrete frequencies (F(1,102)=0, p<0.98). A mixed-model repeated measures ANOVA revealed a significant transducer by frequency interaction (F(10,102)=13.0, p<0.0001). Significant differences were present at 200 and 400 Hz where the mean t-coil output was less than the mean microphone output, and at 4000, 5000, and 6300 Hz where the mean t-coil output was greater than the mean microphone output. CONCLUSIONS: The mean t-coil output was significantly lower than the mean microphone output at 400 Hz, a frequency that lies within the typical telephone bandwidth of 300–3300 Hz. This difference may partially help to explain why some patients often complain the t-coil fails to provide sufficient loudness for telephone communication

Polarization squeezing of light by single passage through an atomic vapor

We have studied relative-intensity fluctuations for a variable set of orthogonal elliptic polarization components of a linearly polarized laser beam traversing a resonant $^{87}$Rb vapor cell. Significant polarization squeezing at the threshold level (-3dB) required for the implementation of several continuous variables quantum protocols was observed. The extreme simplicity of the setup, based on standard polarization components, makes it particularly convenient for quantum information applications.Comment: Revised version. Minor changes. four pages, three figure

Nighttime air quality under desert conditions

Nighttime concentrations of the gas phase nitrate radical (NO3) were successfully measured during a four week field campaign in an arid urban location, Reno Nevada, using long-path Differential Optical Absorbance Spectrometry (DOAS). While typical concentrations of NO3 ranged from 5 to 20ppt, elevated concentrations were observed during a wildfire event. Horizontal mixing in the free troposphere was considerable because the sampling site was above the stable nocturnal boundary layer every night and this justified a box modeling approach. Process analysis of box model simulations showed NO3 accounted for approximately half of the loss of internal olefins, 60% of the isoprene loss, and 85% of the α-pinene loss during the nighttime hours during a typical night of the field study. The NO3+aldehyde reactions were not as important as anticipated. On a polluted night impacted by wildfires upwind of the sampling location, NO3 reactions were more important. Model simulations overpredicted NO2 concentrations for both case studies and inorganic chemistry was the biggest influence on NO3 concentrations and on nitric acid formation. The overprediction may be due to additional NO2 loss processes that were not included in the box model, as deposition and N2O5 uptake had no significant effect on NO2 levels

Development of innovative hybrid sandwich panel slabs: Advanced numerical simulations and parametric studies

The authors honestly appreciate the collaboration of the following institutions: Civitest for developing DHCC materials and PIEP for conducting VARTM process.An innovative hybrid sandwich slab for the rehabilitation of floors in old masonry buildings was conceived, designed, and tested. This structural system is a lightweight composite floor consisting of bottom skin and shear ribs in Glass Fiber Reinforced Polymer (GFRP), a top layer of Deflection Hardening Cement Composites (DHCC), and Polyurethane foam core. In the first part of this study, the material/structural performance of the panel’s concept was assessed by experimental tests. The second part is now dedicated to the execution of advanced numerical simulations, including parametric studies, for assisting on the optimization of this composite slab system and investigating the influence of the relevant characteristics of GFRP and DHCC components. The influence of considering isotropic or orthotropic behavior for the GFRP components and linear or nonlinear behavior for the DHCC are also investigated numerically in terms of accomplishing serviceability and ultimate limit state requisites for this structural system. The parametric studies show that the thickness of GFRP rib is the most important parameter to increase the load carrying capacity of this type of slabs. Based on the results of these parametric studies, two slabs are built and tested experimentally, and the obtained results are not only used to demonstrate the effectiveness of the developed structural system, but also to appraise the predictive performance of the constitutive models adopted in the FEM-based simulations.The study presented in this paper is a part of the research project “RehabGFRP - Rehabilitation of Building Floors with Lightweight High Performance GFRP Sandwich Panels”, with reference number of PTDC/ECM/113041/2009. Furthermore, the authors honestly appreciate the collaboration of the following institutions: Civitest for developing DHCC materials and PIEP for conducting VARTM process

Estudo experimental e numérico sobre o comportamento de vigas mistas com conector Crestbond

Nesta comunicação apresenta-se um estudo sobre vigas mistas em aço e betão onde se utilizam conectores do tipo Crestbond contínuos para estabelecer a ligação entre a viga metálica e a laje de betão e garantir o funcionamento misto entre estes dois elementos. Apresentam-se os resultados de ensaios numéricos e experimentais obtidos em vigas mistas de aço e betão realizadas com conectores Crestbond, na Universidade do Minho. Os provetes consistem numa viga metálica IPE200 com um conector CR40 R10 contínuo, posicionado sobre o banzo superior da viga e soldado em todo o seu desenvolvimento, e uma laje betão armado com secção transversal de 0.40×0.10 m2. Os provetes apresentam um vão de 3.0 m e um comprimento total de 3.2 m. O modelo numérico foi desenvolvido no software Atena 3D.Gostaria de, se possível, agendar um encontro -informal- para conversamos sobre vossa experiência no processo de implantação do RI e mobilização da comunidade acadêmica. Estou à disposição para adequar-me aos seus horários entre os dia 30/11 a 04/12

PINK1 homozygous W437X mutation in a patient with apparent dominant transmission of parkinsonism.

We analyzed the PINK1 gene in 58 patients with early-onset Parkinsonism and detected the homozygous mutation W437X in 1 patient. The clinical phenotype was characterized by early onset (22 years of age), good re- sponse to levodopa, early fluctuations and dyskinesias, and psychiatric symptoms. The mother, heterozygote for W437X mutation, was affected by Parkinson’s disease and 3 further relatives were reported affected, according to an autosomal dominant transmission

Análise experimental e numérica da conexão aço-betão leve realizada com pernos de cabeça

O presente trabalho procura abordar a modelação numérica da conexão entre o perfil metálico e a laje de betão, quando se utilizam conectores do tipo perno e betão leve. Utilizam se elementos finitos de volume para definir todos os elementos presentes na ligação, recorrendo ao software ATENA 3D. A partir dos modelos desenvolvidos procura-se avaliar quais os parâmetros relevantes para o comportamento da conexão aço betão leve. Recorre-se a resultados de ensaios de tipo push out anteriormente realizados na Universidade do Minho para validar os modelos numéricos desenvolvidos