19672 research outputs found
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Widely Tunable Dual-Wavelength Thulium-doped fiber laser Operating in 1.8-2.0 mm Region
No full textIn this work, a tunable dual-wavelength fiber laser (DWFL) with a simple setup is proposed and demonstrated for operation in the 2.0-micron wavelength region. The proposed system employs a ring cavity with a 4-m bi-directionally pumped thulium-doped fiber (TDF) as the linear gain medium, with an inner ring cavity incorporating two tunable bandpass filters (TBPFs) used to generate the desired tunable dual-wavelength output. By fine-tuning the loss of the cavity, peaks of similar intensities for both lasing wavelengths can be obtained by overcoming suppression induced by the homogenous broadening effect, thus producing a stable dual-wavelength output. The widest channel spacing obtained is 183.6 nm, and both lasing wavelengths can be tuned across the 1.8-2.0-micron region by just adjusting the passbands of the TBPFs. The generated dual-wavelength laser has a high signal-to-noise ratio of 66 dB, and its 3-dB bandwidth is measured to be around 0.07 nm. The laser is highly stable, with little-to-none peak fluctuations and no wavelength shift in the lasing wavelengths. The proposed laser is suitable for use in multiple applications near the 2.0-micron region, such as biomedical and industrial applications due to its eye-safe properties
CMF-iteMS: An automatic threshold selection for detection of copy-move forgery
No full textTaking into consideration that the prior CMF detection methods rely on several fixed threshold values in the filtering process, we propose an efficient CMF detection method with an automatic threshold selection, named as CMF-iteMS. The CMF-iteMS recommends a PatchMatch-based CMF detection method that adapts Fourier-Mellin Transform (FMT) as the feature extraction technique while a new automatic threshold selection based on iterative means of regions size (iteMS) procedure is introduced to have flexibility in changing the threshold value for various characteristics (quality, sizes, and attacks) in each input image. To ensure the reliability of the proposed CMF-iteMS, the method is compared with four state-of-the-art CMF detection methods based on Scale Invariant Feature Transform (SIFT), patch matching, multi-scale analysis and symmetry techniques using three available datasets that cover the variety of characteristics in CMF images. The results show that the F-score of the CMF-iteMS outperformed existing CMF detection methods by exceeding an average of 90% F-score values for image-level evaluation and 82% of F-score value for pixel-level evaluation for all datasets in original size. As special attention is given to the image resizing attack, the method is able to maintain the highest performance even if the images in the datasets are resized to 0.25 parameter
Improved ArtGAN for Conditional Synthesis of Natural Image and Artwork
No full textThis paper proposes a series of new approaches to improve generative adversarial network (GAN) for conditional image synthesis and we name the proposed model as 'ArtGAN. ' One of the key innovation of ArtGAN is that, the gradient of the loss function w.r.t. the label (randomly assigned to each generated image) is back-propagated from the categorical discriminator to the generator. With the feedback from the label information, the generator is able to learn more efficiently and generate image with better quality. Inspired by recent works, an autoencoder is incorporated into the categorical discriminator for additional complementary information. Last but not least, we introduce a novel strategy to improve the image quality. In the experiments, we evaluate ArtGAN on CIFAR-10 and STL-10 via ablation studies. The empirical results showed that our proposed model outperforms the state-of-the-art results on CIFAR-10 in terms of Inception score. Qualitatively, we demonstrate that ArtGAN is able to generate plausible-looking images on Oxford-102 and CUB-200, as well as able to draw realistic artworks based on style, artist, and genre. The source code and models are available at: https://github.com/cs-chan/ArtGAN
Enzymatic inhibitory activity of Ficus deltoidea leaf extract on matrix metalloproteinase-2, 8 and 9
No full textDysregulation of matrix metalloproteinases (MMPs) activity is known in many pathological conditions with which most of the conditions are related to elevate MMPs activities. Ficus deltoidea (FD) is a plant known for its therapeutic properties. In order to evaluate the therapeutic potential of FD leaf extract, we study the enzymatic inhibition properties of FD leaf extract and its major bioactive compounds (vitexin and isovitexin) on a panel of MMPs (MMP-2, MMP-8 and MMP-9) using experimental and computational approaches. FD leaf extract and its major bioactive compounds showed pronounced inhibition activity towards the MMPs tested. Computational docking analysis revealed that vitexin and isovitexin bind to the active site of the three tested MMPs. We also evaluated the cytotoxicity and cell migration inhibition activity of FD leaf extract in the endothelial EA.hy 926 cell line. Conclusively, this study provided additional information on the potential of FD leaf extract for therapeutical application. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group
A novel efficient bioflocculant QZ-7 for the removal of heavy metals from industrial wastewater
No full textIn this study, a novel bioflocculant QZ-7 was produced from Bacillus salmalaya 139SI for industrial wastewater treatment. Biochemical analysis, FTIR, scanning electron microscopy-energy dispersive X-ray spectroscopy, and thermogravimetric analysis were performed. A synthetic wastewater sample was used to validate the performance of the prepared OZ-7 for the adsorption efficiency of As, Zn2+ Pb2+, Cu2+, and Cd2+ under optimal experimental conditions such as initial metal concentrations, pH, contact time (h) and QZ-7 adsorbent dosage (mg mL-1). The maximum removal efficiency for Zn2+ (81.3%), As (78.6%), Pb2+ (77.9%), Cu2+ (76.1%), and Cd2+ (68.7%) was achieved using an optimal bioflocculant dosage of 60 mg L-1 at 2 h shaking time, 100 rpm and pH 7. Furthermore, the obtained optimum experimental conditions were validated using real industrial wastewater and the removal efficiencies of 89.8%, 77.4% and 58.4% were obtained for As, Zn2+ and Cu2+, respectively. The results revealed that the prepared bioflocculant QZ-7 has the capability to be used for the removal of heavy metals from industrial wastewater. © 2019 The Royal Society of Chemistry
A Novel Algorithm for Breast Lesion Detection Using Textons and Local Configuration Pattern Features With Ultrasound Imagery
No full textBreast cancer is the most commonly occurring cancer in women worldwide. While mammography remains the gold standard in breast cancer screening, ultrasound is an important imaging modality for both screening and cancer diagnosis. This paper presents a novel method for the detection of breast lesions in ultrasound images using texton filter banks, local configuration pattern features, and classification, without employing any segmentation technique. The developed method was able to accurately detect and classify breast lesions and achieved an accuracy, sensitivity, specificity, and positive predictive value of 96.1%, 96.5%, 95.3%, and 97.9%, respectively. The paradigm that we describe may, therefore, be useful as an effective tool to detect breast nodules during screening and in whole breast imaging, enabling clinicians to focus on images where a lesion is already known to be present. The developed method may also serve as a component for automatic breast nodule detection, and, when found, for the subsequent classification between lesion type benign versus malignant. © 2013 IEEE
The use of using social networking sites in teaching and learning among educators and learners
No full textThis study aims to explore how learners and educators use social networking sites (SNSs) for education-related activities and identify the factors that influence their usage. The study was conducted at a private institute for higher learning (IHL) in central Malaysia involving learners at different levels of study and educators from various positions. A total of 200 respondents consisting of 100 learners and 100 educators participated in the self-administered questionnaire. Chi-square and regression analyses were used to determine the significance of demographic factors (education and gender) and other factors such as perceived privacy (PP), perceived security (PS), perceived trust (PT), web experience (WE), computer anxiety (CA), social norms (SN), enjoyment (ET), desire to give information (GV) and desire to get information (GT) towards their intention to use SNSs. The findings illustrate that other than external factors, demographic factors also influence the use of SNSs for both learners and educators. Copyright © 2019 Inderscience Enterprises Ltd
Influence of school culture and classroom environment in improving soft skills amongst secondary schoolers
No full textThis study aimed to determine the influence of support from the school culture and classroom environment in improving soft skills amongst students. Moreover, the study explored different soft skills, school culture and classroom environments based on gender and type of schools. This study used a quantitative approach by using surveys to gather information. A total of 400 students from three different types of schools were chosen using random sampling. The three types of schools were National Secondary Schools, Religious Secondary Schools, and Technical and Vocational Secondary Schools around Selangor and Federal Territory of Kuala Lumpur. Data were analysed using SPSS 22.0 and AMOS 18. Results confirmed the distinctions of the school culture and classroom environments with the soft skills based on the gender and type of schools. SEM analysis corroborated that the school culture and classroom environment contributed to the development of soft skills. Therefore, schools should come up with programs and approaches to improve the soft skills amongst the students to be proficient in various fields in parallel with the rapid growth of the world. © 2019 Eskisehir Osmangazi University
Multiwavelength operation in praseodymium fiber laser using polarization maintaining fiber and nonlinear polarization rotation in ring cavity
No full textA multiwavelength praseodymium fiber laser (MWPFL) operating at the 1300-nm region is proposed and demonstrated. The MWPFL incorporates a polarization maintaining fiber acting as a Lyot birefringence filter, and when combined with the nonlinear polarization rotation effect, generates the desired multiwavelength output. Careful adjustment of the polarization controller at different angles allows for the generation of up to five channels above a power level of -3.4 dBm and a spacing of 0.2 nm. The peak power fluctuation and wavelength shifts of these lasers are measured to be less than 2.1 dB and 0.04 nm, respectively, over an observation period of 60 min. The demonstrated MWPFL shows good stability combined with a simple structure for generating a multiwavelength output at the 1300-nm wavelength region. © 2019 Society of Photo-Optical Instrumentation Engineers (SPIE)
Effects of TiO2 on the performance of silver coated on side-polished optical fiber for alcohol sensing applications
No full textThis work reports the experimental and numerical investigations on the effect of titanium oxide (TiO2) integrated on the optical fiber silver (Ag) surface plasmon resonance (SPR) sensors. In this paper, the numerical simulation is also analyzed using the finite element method (FEM) which shows good agreement. Results are compared with the experimental findings, focusing on the SPR phenomena for refractive index sensing using side-polished optical fiber, where the characteristics of the Ag layer with the integration of TiO2 are optimized. The essential parameters include the thickness of Ag namely 20 nm, 30 nm and 40 nm for optimization studies of SPR properties. TiO2 was then coated on the Ag thin layer to sense isopropanol at different concentration. It is shown that the combination of a 30 nm thickness of Ag layer with a dielectric TiO2 improves sensor performance in terms of sensitivity reading of 268 nm/RIU with a detection limit of 0.012. The main interest is to develop the device with cost effective, ease fabrication and less cumbersome of sensors using TiO2 which one of an alternative material to defeat the oxidation process and avoid charge recombination. If the sensitivity increases at a higher wavelength, it indicates that the TiO2 holds great potential in photonic applications. © 2019 Elsevier Inc