1,244 research outputs found

    A Comparative Study and Analysis of Query in Encrypted Databases

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    تعد البيانات اليوم هي الموجود الرئيسي للشركات وأعمالها. عادة ما يتم تخزين هذه البيانات في قاعدة البيانات. يجب أن تكون جميع أنظمة قواعد البيانات قادرة على الاستجابة لطلبات الحصول على معلومات من المستخدم وهي استعلامات العمليات. هناك حاجة إلى خوارزميات التشفير التي توفر القدرة على الاستعلام عبر قاعدة البيانات المشفرة وتتيح تحسين تشفير وفك تشفير البيانات. ومع ذلك ، تطبيق خوارزميات التشفير على قاعدة البيانات المشفرة يعتبر التحدي الذي ينشأ هو في  انخفاض اداء النظام الناتج عن نشر خوارزمية التشفير في وقت التشغيل. لذلك ، تعرض هذه الورقة معظم الأعمال الحديثة التي تم إجراؤها على معالجة الاستعلام في  قاعدة البيانات المشفرة وتحليلها لتوضيح تحليل الأداء ، بناءً على مقاييس أداء مختلفة في كل عمل ذي صلةData is the main asset of the modern companies and their businesses. Typically, it is stored in the data-base. Every database system has to be capable of responding to information requests from users, which is queries of the process. Encryption mechanisms are required, which give the capability to the query over the encrypted data-base and permit the optimization of data encryption and decryption. However, applying encryption algorithms on Encrypted database then challenge arises that the efficiency of the system degrades on deploying encryption algorithm on the runtime. Therefore, this paper presents most of the recent works that have been conducted on the query preprocessing of encrypted database and analyzes them to clarify the performance analysis, based on different performance metrics in each related work

    Performance Enhancement of Induction Motor Based on Three-Level T-Type Inverter Using DTC-SVM

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    Induction motors (IM) that are driven using the conventional direct torque control algorithm (DTC) suffer from vital drawbacks which are high ripples in the torque and flux. These ripples result due to the use of a look-up table and hysteresis comparators which causes variable switching frequency. Moreover, the use of a traditional two-level inverter leads to the production of low-quality voltage and current. The work presented in this paper proposed a modified control system to overcome these drawbacks. The proposed control system is based on the use of the space vector modulation-based DTC algorithm (DTC-SVM) for driving three-phase IM via a three-level T-Type inverter. The conventional DTC-SVM algorithm has been modified to match the work of the proposed inverter. The modification process was based on the mapping of the standard DTC-SVM algorithm in the space vector of the three-level inverter. The conventional and the modified control systems are implemented using MATLAB/Simulink package. The comparison of the standard and the modified DTC-SVM has been performed by simulation. Simulation results showed the superiority of the proposed algorithm in terms of reducing ripple in torque and flux and improving the quality of current and voltage supplied to the motor

    Utilization of Synthesized Nano-Zinc Oxide in Yellow Basic Dye Decontamination from Industrial Wastewater

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    ZnO nanorod has been successfully synthesized through the reduction of Zinc chloride salt with ammonia solution in the presence of triethanolamine (TEA) as surfactant agent via hydrothermal technique. The properties of the produced material were determined using different characterization techniques such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and Fourier Transform Infrared spectrum (FTIR). The results showed that the asprepared ZnO are rod- like morphologies at pH equal to 10. The synthesized nano rod-zinc oxide was employed asadsorbent agent for basic yellow 28 dye decolorization from polluted industrial wastewater. The synthesized nano-ZnO was achieved 93.26% dye decolorization affinity with in 60minutes. The variation in the different processing parameters on the dye sorption process was elucidated using batch technique. The increment in both the dye solution pH and its  temperature was association with decline in the decolourization process. The optimum nano-zinc oxide dosage was recorded to be equal to 10 g/L. The adsorption data at equilibrium were analyzed using Langmuir, Freundlich and Temkin equilibrium isotherms. The experimental results confirmed the applicability of synthesized nano-zinc oxide as adsorbent agent for dye decontamination from polluted wastewater.Keywords: nano-zinc oxide, dye decolourization, sorption parameters

    Integration of TTF, UTAUT, and ITM for mobile Banking Adoption

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    The introduction of mobile banking facility has enabled customers to carry out banking transactionswith the use of smartphones and other handheld devices from anywhere. It has become a luxurious and exclusive method of online payments. The recent growth of telecommunication sector and a tremendous increase in mobile USAge has opened new doors for sparking future of banking sector industry. The following research is aimed to find out the mobile banking adoption attitudes with the integration of TTF, UTAUT,and ITM models

    Design and Implementation of Single-Phase Boost PFC Converter

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    In this paper, a single-phase boost type ac-dc converter with power factor correction (PFC) technique is designed and implemented. A current mode control at a constant switching frequency is used as a control strategy for PFC converter. The PFC converter is a single-stage singleswitch boost converter that uses a current shaping technique to reshape the non-sinusoidal input current drawn by the bulky capacitor in the conventional rectifier. This technique should provide an input current with almost free-harmonics, comply with the IEC61000-3-2 limits, and a system operates with near unity power factor. The other function of the boost converter that should be accomplished is to provide a regulated DC output voltage. The complete designed system is simulated in MATLAB/SIMULINK and a hardware prototype has been built using analog devices. Simulation results and experimental results are presented to validate the proposed system

    Magmatic Evolution and Rare Metal Mineralization in Mount El-Sibai Peralkaline Granites, Central Eastern Desert, Egypt: Insights from Whole-Rock Geochemistry and Mineral Chemistry Data

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    The Ediacaran peralkaline granites, which were emplaced during the post-collisional tectonic extensional stage, have a limited occurrence in the northern tip of the Nubian Shield. In this contribution, we present new mineralogical and geochemical data of Mount El-Sibai granites from the Central Eastern Desert of Egypt. The aim is to discuss their crystallization condition, tectonic setting, and petrogenesis as well as the magmatic evolution of their associated mineralization. Mount El-Sibai consists of alkali-feldspar granites (AFGs) as a main rock unit with scattered and small occurrences of alkali-amphibole granites (AAGs) at the periphery. The AAG contain columbite, nioboaeschynite, zircon and thorite as important rare metal-bearing minerals. Geochemically, both of AFG and AAG exhibit a highly evolved nature with a typical peralkaline composition (A/CNK = 0.82–0.97) and formed in within-plate anorogenic setting associated with crustal extension and/or rifting. They are enriched in some LILEs (Rb, K, and Th) and HFSEs (Ta, Pb, Zr, and Y), but strongly depleted in Ba, Sr, P and Ti with pronounced negative Eu anomalies (Eu/Eu* = 0.07–0.34), consistent with an A-type granite geochemical signature. The calculated TZrn (774–878 °C) temperatures indicate that the magma was significantly hot, promoting the saturation of zircon. The texture and chemistry of minerals suggest that they were crystallized directly from a granitic magma and were later subject to late- to post-magmatic fluids. Both granitic types were most likely generated through partial melting of a juvenile crustal source followed by magmatic fractionation. The lithospheric delamination is the main mechanism which causes uplifting of the asthenospheric melts and hence provides enough heat for crustal melting. The produced parent magma was subjected to prolonged fractional crystallization to produce the different types of Mount El-Sibai granites at different shallow crustal levels. During magma fractionation, the post-magmatic fluids (especially fluorine) contribute significantly to the formation of rare metal mineralization within Mount El-Sibai granites

    ETIOLOGY AND RISK FACTORS OF STOMATITIS AMONG YEMENI DENTURE WEARERS

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    Objectives: Denture stomatitis (DS) is a benign condition, usually asymptomatic, that can affect denture wearer’s patients. The aim of this study was to describe the etiology of DS among Yemeni denture wearers and the risk factors of DS. A cross sectional study was carried out at Prothodontics Departments at the Faculty of Dentistry- Sana'a University, Sana’a city –Yemen. Methods: The study group consisted of 288 denture wearers' patients' contracting DS. The microbiological samples were collected by wiping sterile swabs on upper and lower denture fitting surfaces. Then, they were directly cultured for Candida in Chromomeric agar media and for bacteria in standard selective media, using standard bacteriological methods.  Results: The most common microbial cause of DS was C. albicans (58.3%), followed by S. mutans (17%), while S. aureus (4.9%), lactobacillus (3.1%) and C. glabrata (4.2%) were less common. There was an association between male patients, older age group and longer period of denture wearers with high risk of contracting candidal DS and bacterial DS. Most of those patients were suffering from DS Type I and few from Type II, but no case of DS Type III was found. Ending, DS is a condition that commonly affects denture wearers, and should be treated even if asymptomatic. The condition requires a combined treatment approach from both patient and clinician, and the role of the patient must be stressed. Conclusion: Management of aetiological risk factors is key in order to prevent recurrence. Treatment modalities may include: treatment of any underlying systemic risk factors, improvement in the fit of existing dentures, replacement of existing dentures, improved denture hygiene and the use of antifungal agents. Whichever methods are employed, the main aim of treatment is to eradicate the biofilm from the patient’s dentures. Peer Review History: Received 11 January 2017; Revised 13 February; Accepted 27 February, Available online 15 March 2018 Received file:        Reviewer's Comments: Average Peer review marks at initial stage: 4.5/10 Average Peer review marks at publication stage: 8.0/10 Reviewer(s) detail: Dr. Marwa A. A. Fayed, University of Sadat City, Egypt, [email protected] Dr. Masoumeh Divar, Shiraz University, Shiraz, Iran, [email protected] Similar Articles: RISK FACTORS OF PERIODONTAL DISEASES AMONG YEMENI YOUNG DENTAL PATIENTS SERO-PREVALENCE OF HEPATITIS C VIRUS AMONG DENTAL CLINIC WORKERS IN SANA’A CITY- YEMEN AND THE RISK FACTORS CONTRIBUTING FOR ITS INFECTIO

    Digital readiness for social educators in health care and online learning during covid-19 pandemic: a bibliometric analysis

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    Digital technologies have been earsplittingly discussed for a long time with multi-sides of enormous benefits and challenges in educational application. When the Covid19 pandemic has outbreak worldwide, global governments have popularly employed the movement control order (MCO) and social distances policies, international borders closed, schools and higher education applied for fully online courses. Several studies show that digital readiness is the crucial factor that significantly impacts students' satisfaction and success in online learning. This study will analyze the overall resources and digital readiness in multi-sides to enhance student learning and development outcomes through an online learning environment. To reach the objectives, the literature accessed of Scopus and web of science databases. The systematic review employed and the finally adapted criteria 32 articles are selected. The bibliometric analysis will conduct for to identify the cluster themes based on texting frequency. The process of vital steps of data classification follow seriously and carefully in platform of concept, findings, author's reputation and years published. In the last findings of the study, reports will explain past literature and recent outbreak. The findings cover three main themes: digital readiness in learning management, digital readiness for learners, and digital readiness for educators. During the covid19 pandemic, the concept of digital readiness for educators concealed in both healthcare advising and lesson teaching in home-based learning models. These findings are expected to benefit stakeholders involved in online teaching and learning during and resilient post-Covid-19 pandemic

    A Simple Pre-concentration Method for the Determination of Nickel(II) in Urine Samples Using UV-Vis Spectrophotometry and Flame Atomic Absorption Spectrometry Techniques

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    The cloud point technique was effectively utilized for extraction and pre-concentration of nickel(II) in urine samples before measurement by UV-Vis spectrophotometer and AAS techniques. The metal response to a para-aminophenol (PAP) reagent in a non-ionic surfactant Triton X-114 medium was to form the Ni-PAP complex. The adopted concentration for PAP, concentration of Triton X-114, pH effect and water bath temperature, incubation time, salt effect, and interference effects were all optimized. The calibration curve was linear over the range of (0.0625–1.25) mg L–1 with a correlation coefficient r2 of 0.9682 for the UV-Vis spectrophotometer at a λmax of 629 nm. The limit of detection was 0.005 mg/L. The relative standard deviation for six replicates was 1.07%. This method was applied successfully to determine copper (II) concentrations in 44 urine samples of occupational worker samples as determined by UV-Vis spectrophotometry and FAAS techniques

    Utilization of Synthesized Nano-Zinc Oxide in Yellow Basic Dye Decontamination from Industrial Wastewater

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    ZnO nanorod has been successfully synthesized through the reduction of Zinc chloride salt with ammonia solution in the presence of triethanolamine (TEA) as surfactant agent via hydrothermal technique. The properties of the produced material were determined using different characterization techniques such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and Fourier Transform Infrared spectrum (FTIR). The results showed that the as prepared ZnO are rod- like morphologies at pH equal to 10. The synthesized nano rod-zinc oxide was employed as adsorbent agent for basic yellow 28 dye decolorization from polluted industrial wastewater. The synthesized nano-ZnO was achieved 93.26% dye decolorization affinity with in 60minutes. The variation in the different processing parameters on the dye sorption process was elucidated using batch technique. The increment in both the dye solution pH and its temperature was association with decline in the decolorization process. The optimum nano-zinc oxide dosage was recorded to be equal to 10 g/L. The adsorption data at equilibrium were analyzed using Langmuir, Freundlich and Temkin equilibrium isotherms. The experimental results confirmed the applicability of synthesized nano-zinc oxide as adsorbent agent for dye decontamination from polluted wastewater
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