A Model For General Periodic Excitation With Random Disturbance and its Application

Many vibration problems involve a general periodic excitation such as those of a triangular or rectangular waveform. In practice, the periodic excitation may become disordered due to uncertainties. This paper presents a stochastic model for general periodic excitations with random disturbances which is constructed by introducing random amplitude and phase disturbances to individual terms in the Fourier series of the corresponding deterministic periodic function. Mean square convergence of the random Fourier series are discussed. Monte Carlo simulation of disordered sawtooth, triangular, and quadratic wave forms are illustrated. An application of the excitation is demonstrated by vibration analysis of a single-degree-of-freedom (SDOF) hydraulic valve system subjected to a disordered periodic fluid pressure. In the present study only the phase disturbance is considered. Effects of the intensity of phase modulation on up to fourth order moment response and the convergence rate of the random Fourier series are studied by numerical results. It is found that a small random disturbance in a general periodic excitation may significantly change the response moment

The Effect of Cognitive–Behavioral Group Therapy on Menopausal Symptoms

BACKGROUND AND OBJECTIVE: The common symptoms of menopause are associated with anxiety and discomfort for most women, and this is one of the major healthcare challenges. The aim of this study was to evaluate the effect of cognitive – behavioral group therapy on menopausal symptoms (primary outcome). METHODS: This randomized controlled clinical trial was conducted among 90 menopausal women with health records at two health centers in Tuyserkan in 2016 and were randomly assigned to two groups of intervention and control (45 patients in each group). To perform cognitive – behavioral group therapy, six 90-minute sessions were held for the intervention group for six consecutive weeks. Menopausal symptoms were discussed in each of these sessions based on cognitive techniques such as identifying negative automatic thoughts and behavioral techniques such as diaphragmatic breathing technique. Menopausal symptoms were assessed in both groups using the Greene Climacteric Scale (0 – 63) before the intervention and at the end of the sixth week. To adhere to ethics, the control group received one session of educational counseling after the assessments were done. FINDINGS: There was no statistically significant difference in mean total Greene score between the cognitive– behavioral group (22.78±12.22) and control group (24.8±10.25) before intervention. After the intervention, the mean total Greene score decreased significantly in the cognitive – behavioral group (15.75±7.24) compared to the control group (24.97±9.25) (p < 0.05). CONCLUSION: The results showed that cognitive – behavioral group therapy can decrease menopausal symptoms

Home-based transcranial direct current stimulation in bipolar depression: an open-label treatment study of clinical outcomes, acceptability and adverse events

Current treatments for bipolar depression have limited effectiveness, tolerability and acceptability. Transcranial direct current stimulation (tDCS) is a novel non-invasive brain stimulation method that has demonstrated treatment efficacy for major depressive episodes. tDCS is portable, safe, and individuals like having sessions at home. We developed a home-based protocol with real-time remote supervision. In the present study, we have examined the clinical outcomes, acceptability and feasibility of home-based tDCS treatment in bipolar depression

Surface/interface engineering of InAs quantum dot edge-emitting diodes toward III-V/SiN photonic integration

We investigate the surface and interface engineering on InAs quantum dot (QD) emitters, by fabricating and measuring a series of edge-emitting light-emitting diodes. These diodes are encapsulated with non-stoichiometric silicon nitride (SiN) layers with various refractive indices. By analysing the optical and electrical characteristics, it is concluded that Si-rich SiN is an excellent candidate for both electrical and optical passisvations with reduced surface recombination. While the N-rich SiN deposited by the same method shows an improved device performance under optical pumping, the passivation does not appear to be as effective under electrical injection. Our findings provide important information related to the surface engineering of the interface between InAs QD stacks and non-stoichiometric SiN materials, which is arguably one of the crucial steps required to establish monolithic integration of InAs QD emitters with CMOS photonics components

Photoluminescence studies of individual and few GaSb/GaAs quantum rings

We present optical studies of individual and few GaSb quantum rings embedded in a GaAs matrix. Contrary to expectation for type-II confinement, we measure rich spectra containing sharp lines. These lines originate from excitonic recombination and are observed to have resolution-limited full-width at half maximum of 200 µeV. The detail provided by these measurements allows the characteristic type-II blueshift, observed with increasing excitation power, to be studied at the level of individual nanostructures. These findings are in agreement with hole-charging being the origin of the observed blueshif

A multi-weapon detection using ensembled learning

Recently, the level of criminals and terrorists using light weapons (such as knives and firearms) has increased rapidly around the world. Unfortunately, most current surveillance systems are still based mainly on human monitoring and intervention. For that reason, the requirement for a smart system for detecting different weapons becomes crucial in the field of security and computer vision. In this article, a novel technique for detecting various types of weapons has been proposed. This system is based mainly on deep learning techniques, namely, You Only Look Once, version 8 (YOLOv8), to detect a different class of light weapons. Furthermore, this study focuses on detecting two armed human poses based on ensemble learning techniques, which involve combining the outputs of different Yolov8 models to produce an accurate and robust detection system. The proposed system is evaluated on the self-created weapons dataset comprising thousands of images of different classes of weapons. The experiment results of this work show the effectiveness of ensemble learning for detecting various weapons with high accuracy, achieving 97.2% of mean average precision

A thermally erasable silicon oxide layer for molecular beam epitaxy

We present a systematic study of the oxidation and deoxidation behaviours of several kinds of ultrathin silicon oxide layers frequently used in silicon (Si) technology, which in this work serve as surface protecting layers for molecular beam epitaxy (MBE). With various characterization techniques, we demonstrate that a chemically grown silicon oxide layer is the most promising candidate for subsequent removal in an ultra-high vacuum chamber at a temperature of 1000 ∘C, without making use of a reducing agent. As a demonstration, a tensile-strained Ge(100) layer is epitaxially grown on the deoxidised wafer with an atomically flat surface and a low threading dislocation density of 3.33 × 108 cm−2. Our findings reveal that the ultra-thin oxide layer grown using a chemical approach is able to protect Si surfaces for subsequent MBE growth of Ge. This approach is promising for the growth of III/V-on-Si (using Ge as a buffer) and all group-IV related epitaxy for integration on the Si photonics platforms