1,606 research outputs found

    A General Study on Langevin Equations of Arbitrary Order

    Get PDF
    In this paper, the broad study depends on Langevin differential equations (LDE) of arbitrary order.The fractional order is in terms of ψ-Hilfer fractional operator. This work reveals the dynamicalbehaviour such as existence, uniqueness and stability solutions for LDE involving ψ-Hilfer fractionalerivative (HFD). Thus the fractional LDE with boundary condition, impulsive effect and nonlocalconditions are taken in account to prove the result

    Mastitogenic Bacteria Isolated from Clinical Mastitis Cases Associated with Teat Lesions and their Antimicrobial Sensitivity

    Get PDF
    Mastitis is the most common and most expensive disease that impacts dairy farms in Egypt. In this study, we investigated bacterial mastitis cases that did not respond to antimicrobial treatment from buffaloes and cows. Milk samples (11) were collected from diseased animals (5 buffaloes and 6 cows). The samples were tested microbiologically to isolate and identify the causative bacteria and antimicrobial susceptibility. The antimicrobial sensitivity of the isolated bacteria was tested by using minimum inhibitory concentration technique according to the clinical national laboratory standards.  The total number of bacterial isolates from the cases was 15 isolates. Staphylococcus aureus (S. aureus) was isolated alone in two cases (13.33% of the isolates), and S. aureus isolated in combination with Arcanobacterium pyogenes (A. pyogenes) in one case (6.67%), and S. aureus isolated in combination with both A. pyogenes and Streptococcus agalactiae (S. agalactiae) in two cases (13.33%), and Coagulase negative staphylococci (CNS) isolated alone in one case (6.67%), and CNS isolated in combination with Klebsiella pneumoniae in one case (6.67%), and A. pyogenes isolated alone in two cases (13.33%). In two cases were not able to isolate any bacterial pathogen. In terms of susceptibility to antibiotics, the isolated strains were sensitive to clindamycin with MICs ranging from 0.125 to <0.03125 µM. The same isolates exhibited medium sensitivity to gentamicin and ciprofloxacin with MICs ranging from 0.5 to 8 µM. Most S. aureus isolates were resistant to oxytetracycline with a MIC of 128 µM. Most of the isolated bacteria were resistant to polymyxin B with a MIC > 128 µM. With the exception of the A. pyogenes isolates, all the isolated bacteria were sensitive to enrofloxacin with a MIC <1 µM.       &nbsp

    Melting and Solidification Study of As-Deposited and Recrystallized Bi Thin Films

    Get PDF
    Melting and solidification of as-deposited and recrystallized Bi crystallites, deposited on highly oriented 002-graphite at 423 K, were studied using reflection high-energy electron diffraction (RHEED). Films with mean thickness between 1.5 and 33 ML (monolayers) were studied. Ex situ atomic force microscopy was used to study the morphology and the size distribution of the formed nanocrystals. The as-deposited films grew in the form of three-dimensional crystallites with different shapes and sizes, while those recrystallized from the melt were formed in nearly similar shapes but different sizes. The change in the RHEED pattern with temperature was used to probe the melting and solidification of the crystallites. Melting started at temperatures below the bulk melting point of Bi, T0=544.5 K, and extended over a temperature range that depended on the size distribution of the crystallites. The as-deposited 1.5 ML film started to melt at T0-50 K and melted completely at T0-20 K. For films with higher coverage, the size distribution was observed to spread over a wider range with a larger mean value, resulting in a shift in the melting temperature range towards higher temperatures. Due to the shift in size distribution to higher values upon recrystallization, the recrystallized Bi crystallites showed a melting temperature range higher than that of the as-deposited crystallites. For the investigated conditions, all films were completely melted below or at T 0 of Bi. The characteristic film melting point, defined as the temperature at which the film melting rate with temperature is the fastest, showed a linear dependence on the reciprocal of the average crystallite radius, consistent with theoretical models. Of these models, the surface-phonon instability model best fits the obtained results. During solidification, the Bi films showed high amount of supercooling relative to T0 of Bi. The amount of liquid supercooling was found to decrease linearly with the reciprocal of the average crystallite size. © 2006 American Institute of Physics. [DOI: 10.1063/1.2208551

    Condensation on (002) Graphite of Liquid Bismuth Far Below Its Bulk Melting Point

    Get PDF
    Condensation of thermally evaporated Bi on (002) graphite, at temperatures of 300-523K, was studied using in situ reflection high-energy electron diffraction (RHEED) and room temperature ex situ atomic force microscopy (AFM). For deposition at temperatures below 415±5K, transmission RHEED patterns of Bi appeared at an average thickness of ∼0.5 monolayer (ML). AFM images showed that the film consisted of crystallites in the shape of triangular step pyramids with step heights corresponding to single and double Bi layers in the [111] direction. This morphology indicates crystallization from the vapor. For deposition at higher temperatures, diffuse RHEED patterns appeared independent of the deposited thickness. When these films were cooled, clear transmission patterns of crystalline Bi appeared. After cooling to near room temperature, the melting and solidification behaviors of these films were investigated with RHEED. Upon subsequent heating, the topmost layers of the probed Bi crystallites started to lose long-range order at ∼10-15K below the Bi bulk melting point, T0=544.52K. When crystallized from the melt, supercooling by ∼125K below T0 was observed. These results indicate that Bi condensed on graphite in the form of supercooled liquid droplets when the graphite temperature was above 419K (T0-125). Below that temperature, Bi condensed in the solid phase. Bi films crystallized by cooling the liquid had crystal morphologies that depended on the degree of liquid supercooling. © 2005 The American Physical Society

    Effects of contact resistance and metal additives in finned-tube adsorbent beds on the performance of silica gel/water adsorption chiller

    Get PDF
    Recently interest in adsorption cooling systems has increased due to their capability to utilise low grade heat sources and environmentally friendly refrigerants. Currently, most of the commercially available adsorption cooling systems utilise granular packed adsorbent beds. Enhancing the heat transfer process inside the adsorbent bed will improve the overall efficiency of the adsorption system. Using recently developed empirical lumped analytical simulation model for a 450 kW two-bed silica gel/water adsorption chiller, this paper theoretically investigates the effects of various adsorbent bed heat transfer enhancement techniques on the adsorption system cooling capacity. Firstly, coating the first adsorbent layer to the metal part and packing the rest of adsorbent granules to eliminate the thermal contact resistance between heat exchanger metal and granules while keeping the same level of permeability. Secondly, adding metal particles to the adsorbent in order to enhance the granules thermal conductivity. The effective thermal conductivity of adsorbent/metal mixtures were determined and validated by comparing it with published experimental data. Also, the combined effect of using both techniques simultaneously was investigated. All these investigations were carried out at various adsorption bed fin spacing. Results of the combined techniques showed that the enhancement in the cooling capacity and system coefficient of performance (COP) increased with increasing the fin spacing ratio to reach maximum of 25% and 10% respectively at fin spacing ratio of 2

    Atomic Hydrogen Cleaning of InP(100) for Preparation of a Negative Electron Affinity Photocathode

    Get PDF
    Atomic hydrogen cleaning is used to clean InP(100) negative electron affinity photocathodes. Reflection high-energy electron diffraction patterns of reconstructed, phosphorus-stabilized, InP(100) surfaces are obtained after cleaning at ∼400 °C. These surfaces produce high quantum efficiency photocathodes (∼8.5%), in response to 632.8 nm light. Without atomic hydrogen cleaning, activation of InP to negative electron affinity requires heating to ∼530 °C. At this high temperature, phosphorus evaporates preferentially and a rough surface is obtained. These surfaces produce low quantum efficiency photocathodes (∼0.1%). The use of reflection high-energy electron diffraction to measure the thickness of the deposited cesium layer during activation by correlating diffraction intensity with photoemission is demonstrated. © 1998 American Institute of Physics

    A New Method for Grain Texture Manipulation in Post-Deposition Niobium Films

    Get PDF
    Niobium films are frequently grown using forms of energetic condensation, with modest substrate temperatures to control grain structure. As an alternative, energetic deposition onto a cold substrate results in a dense amorphous film, with a much larger energy density than the re-crystallized state. Re-crystallization is then performed using a pulsed UV (HIPPO) laser, with minimal damage to the substrate. In addition, a graded interface between the substrate and Nb film is created during the early stages of energetic deposition. Experimental approach and apparatus are described

    Evolutionary framework with reinforcement learning-based mutation adaptation

    Get PDF
    Although several multi-operator and multi-method approaches for solving optimization problems have been proposed, their performances are not consistent for a wide range of optimization problems. Also, the task of ensuring the appropriate selection of algorithms and operators may be inefficient since their designs are undertaken mainly through trial and error. This research proposes an improved optimization framework that uses the benefits of multiple algorithms, namely, a multi-operator differential evolution algorithm and a co-variance matrix adaptation evolution strategy. In the former, reinforcement learning is used to automatically choose the best differential evolution operator. To judge the performance of the proposed framework, three benchmark sets of bound-constrained optimization problems (73 problems) with 10, 30 and 50 dimensions are solved. Further, the proposed algorithm has been tested by solving optimization problems with 100 dimensions taken from CEC2014 and CEC2017 benchmark problems. A real-world application data set has also been solved. Several experiments are designed to analyze the effects of different components of the proposed framework, with the best variant compared with a number of state-of-the-art algorithms. The experimental results show that the proposed algorithm is able to outperform all the others considered.</p

    Detecting anomalies in security cameras with 3D-convolutional neural network and convolutional long short-term memory

    Get PDF
    This paper presents a novel deep learning-based approach for anomaly detection in surveillance films. A deep network that has been trained to recognize objects and human activity in movies forms the foundation of the suggested approach. In order to detect anomalies in surveillance films, the proposed method combines the strengths of 3D-convolutional neural network (3DCNN) and convolutional long short-term memory (ConvLSTM). From the video frames, the 3DCNN is utilized to extract spatiotemporal features,while ConvLSTM is employed to record temporal relationships between frames. The technique was evaluated on five large-scale datasets from the actual world (UCFCrime, XDViolence, UBIFights, CCTVFights, UCF101) that had both indoor and outdoor video clips as well as synthetic datasets with a range of object shapes, sizes, and behaviors. The results further demonstrate that combining 3DCNN with ConvLSTM can increase precision and reduce false positives, achieving a high accuracy and area under the receiver operating characteristic-area under the curve (ROC-AUC) in both indoor and outdoor scenarios when compared to cuttingedge techniques mentioned in the comparison

    Interference Effects of Salinity on Growth and Some Metabolic Activities of Two Chlorella Species

    Get PDF
    The unicellular green algae Chlorella minutissima and Chlorella oocystoides were isolated from different regions in Upper Egypt. The effect of different concentrations of salinity (100, 250 and 500 mM NaCl) on growth parameters (optical density, dry weight, and total photosynthetic pigments) and primary products (total carbohydrates, total proteins, and lipids contents) were measured after 7 days. The growth parameters, and the primary products of Chlorella minutissima and Chlorella oocystoides were significantly increased at lower and moderate concentrations (100 and 250 mM NaCl). Under higher concentration 500 mM of NaCl, the growth parameters, and the primary products (total carbohydrates, and total proteins) were significantly decreased. However, the lipid contents were markedly increased.Keywords: Chlorella minutissima, Chlorella oocystoides, cell growth, total carbohydrates, total proteins and lipid contents
    • …
    corecore