A NEW METHOD IN THE IDENTIFICATION OF NOISE AND VIBRATION CHARACTERISTICS OF AUTOMOTIVE DISK BRAKES IN THE LOW FREQUENCY DOMAIN

Noise and vibration characterization is an important benchmark to reduce brake noise.Brake noise and vibration measurement is commonly done on an actual vehicle or on a brake dynamometer. A full scale brake dynamometer takes into account the attached mass which resembles the mass of a quarter scale vehicle. This paper proposes a testing method which eliminates the need for attached masses. This is achieved through the scaling of the brake system parameters to accommodate the loss of mass and produce similar conditions to those in actual braking. The measurement of noise and vibration is measured simultaneously and an FFT is performed to identify the frequencies of noise and vibration. An experimental modal analysis (EMA)is done to obtain the frequencies which the brake system tends to produce as a validation to the proposed method. It is shown that through this method the noise and vibration characteristics of the brake system and the unstable frequencies can be identified

A Parallel Study of Vibration Analysis and Acoustic Analysis in Low Frequency Brake Noise

An acoustic analysis in the investigation of brake noise shows the severity of the noise and its characteristics and a vibration analysis shows the excitation of noise that is present in the braking event. In this study, vibration and acoustic analyses were used to study the brake noise which is produced during braking. Vibration and acoustic data were collected simultaneously during braking to identify the braking condition. The data analysis focuses on the low frequency domain. The Fast Fourier method was used to analyse the vibration and acoustic signals. The computation of FFT was done independently and the frequency domains obtained were compared. The parallelism in the analysis was used to identify the acoustic source. The determination of the source will aid in brake noise reduction efforts and reinforce the vibration analysis method as a system identification method for brake noise

An Analytical Model to Identify Brake System Vibration within the Low Frequency Domain

This paper presents the analytical model of a brake system to investigate the low frequency vibration. The purpose of this study is to model and validate brake system vibration. The brake model was developed by applying the theory of sinusoidal traveling waves and wave super positioning. An experimental modal analysis (EMA) of the brake disc has been carried out to obtain the natural frequencies. Wave equations were then formulated based on the experimental data. These waves are super positioned to be shown as a single spatial and temporal function that will provide periodic excitation to the brake pad. The brake pad was modeled as a beam element with distributed friction force. The differential equations were solved using Green's dynamic formulation. The model is capable of predicting vibration behavior of the brake pad for whole range below 1 kHz which has shown strong agreement with the experimental results validated through in-house brake dynamometer. This brake model can serve as a tool to investigate the relationship between braking parameters and other variables within the brake system

Evaluation of 2.1µm DFB lasers for space applications

This paper presents the results obtained in the frame of an ESA-funded project called “Screening and Preevaluation of Shortwave Infrared Laser Diode for Space Application” with the objective of verifying the maturity of state of the art SWIR DFB lasers at 2.1µm to be used for space applications (mainly based on the occultation measurement principle and spectroscopy). The paper focus on the functional and environmental evaluation test plan. It includes high precision characterization, mechanical test (vibration and SRS shocks), thermal cycling, gamma and proton radiation tests, life test and some details of the Destructive Physical Analysis performed. The electro-optical characterization includes measurements of the tuning capabilities of the laser both by current and by temperature, the wavelength stability and the optical power versus laser current

The Effects of Carbon Emissions and Agency Costs on Firm Performance

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Differential Biofeedback Intervention In Moderating Inhibited Performance In Soccer

Performance excellence in soccer crucially depends on mental toughness or more specifically the aspect of emotional flexibility and hardiness of the player. Since indices of projective evaluations can reveal hidden emotional crises and internal conflicts, psychobiological evaluations could substantiate with the inner emotionality revealed to provide etiological information related to performance hindrances in soccer. Present study was carried out to identify the efficacy of skin conductance (Sc) biofeedback in regulation of sudomotor nerve activity (SNA) and of electromyography (EMG) biofeedback in regulation of peak torque and maximal voluntary contraction (MVC) in modification of performance catastrophe in soccer. All of them were assessed with autonomic measures (SNA and Sc amplitude); electromyography evaluation of emotionality and MVC revealed through EMG. Forty National-selection group soccer players of Malaysia were randomly categorized into four groups (Gr. A, N = 10, no-intervention control group); Gr. B (who received Sc biofeedback training); Gr. C (received EMG biofeedback intervention) and Gr. D (players who received combined training of Sc and EMG biofeedback intervention). Players of intervention groups received their respective trainings for 12 weeks (15 min.s /day for 3 days/ week). Postintervention analyses revealed marked improvement in the soccer players who received Sc and EMG biofeedback intervention, and the combined biofeedback training was evident as most efficient intervention technique in modulating emotionality as well as muscle potentiality. Analysis of variance and repeated measure of ANOVA were done to observe shared aetiology in the form of direct, inverse and supportive relationships between psychobiological and emotional indices related to performance crises in soccer. Comprehensive understanding of the confounding relationships between subjective feelings emotionality and corroborative psychobiological indices as predictor of high performance was achieved

The optimisation of a turbulent swirl nozzle using CFD

Swirl is imparted into free and impinging nozzle flows as well as jet flames to affect convective heat transfer, fluid mixing or flame stability. At the nozzle exit plane, the emerging flow strongly influences downstream flow development and so factors which impact upon the emitted flow are worthy of study. This paper presents preliminary CFD analyses into the effect of design parameters and operational settings on the emerging flow at the exit plane for a swirl nozzle (Remax~30,500). The research was conducted in the premanufacture stage to optimise the nozzle. Swirl is aerodynamically generated using multiple tangential ports located upstream of the exit plane and the streamwise flow is augmented with flow from two axial ports located at the nozzle base. Before reaching the exitplane, all flows pass through a contraction en route to a straight section of length (L). Factors studied in this paper include the angle of (inlet) tangential ports, the total length of the straight section (L), the ratio of axial-to-tangential inflows and the Reynolds number. Results show that larger tangential port angles and a shorter straight section help develop a modestly greate

The status of retinoblastoma gene expression in brain tumors

Objective: Malignant brain tumors, including Glioblastoma Multiforme (GBM), are among the deadliest brain tumors. Given the fact that the expression of the retinoblastoma (RB) gene in malignant tumors can change the tumor behavior, we seek to investigate the alterations of RB expression in brain tumors. Materials and Methods: The archives of the Pathology Department of Yazd Hospitals were examined, and all the brain tumors diagnosed between 2013 and 2017 were extracted. All paraffin embedded blocks underwent immunohistochemical staining for RB gene expression. Based on a pre-set checklist, demographics data, tumor type, location, and survival status were entered into and analyzed by SPSS version 25. p-value less than 0.05 was considered statistically significant. Results: Out of 90 blocks studied, 64.4% belonged to male patients and 35.5% to female patients. The frequencies of brain tumors subtypes were non-glioma (45.6%), low grade astrocytoma (14.4%), anaplastic astrocytoma (18.9%) and GBM (21.1%), respectively. The intensity of RB expression was significantly different between men and women (p-value=0.008), and in different subtypes of the tumors (p=0.04). Multivariate analysis revealed that GBM (HR: 9.933, 95% CI 1.888-52.254, p-value=0.007), age >50 (HR: 8.648, 95% CI 5.116-16.406, p-value= 0.0001), female sex (HR:2.139, 95% CI 1.212-3. 775, p-value= 0.09), RB negative tumors (HR:2.502, 95% CI 1.061-5.896, p-value= 0.036) significantly affect patient survival. Conclusions: There was a significant difference between men and women, and among different subtypes of the brain tumors in terms of RB gene expression. RB expression had a significant effect on patient survival independent from patient’s age, sex, and tumor subtypes

Duplications of the critical Rubinstein-Taybi deletion region on chromosome 16p13.3 cause a novel recognisable syndrome

Background The introduction of molecular karyotyping technologies facilitated the identification of specific genetic disorders associated with imbalances of certain genomic regions. A detailed phenotypic delineation of interstitial 16p13.3 duplications is hampered by the scarcity of such patients. Objectives To delineate the phenotypic spectrum associated with interstitial 16p13.3 duplications, and perform a genotype-phenotype analysis. Results The present report describes the genotypic and phenotypic delineation of nine submicroscopic interstitial 16p13.3 duplications. The critically duplicated region encompasses a single gene, CREBBP, which is mutated or deleted in Rubinstein-Taybi syndrome. In 10 out of the 12 hitherto described probands, the duplication arose de novo. Conclusions Interstitial 16p13.3 duplications have a recognizable phenotype, characterized by normal to moderately retarded mental development, normal growth, mild arthrogryposis, frequently small and proximally implanted thumbs and characteristic facial features. Occasionally, developmental defects of the heart, genitalia, palate or the eyes are observed. The frequent de novo occurrence of 16p13.3 duplications demonstrates the reduced reproductive fitness associated with this genotype. Inheritance of the duplication from a clinically normal parent in two cases indicates that the associated phenotype is incompletely penetrant