2,176 research outputs found

    Investigation of pressure drop in horizontal pipes with different diameters

    Get PDF
    The pressure drop has a significant importance in multiphase flow systems. In this paper, the effect of the volumetric quality and mixture velocity on pressure drop of gas-liquid flow in horizontal pipes of different diameters are investigated experimentally and numerically. The experimental facility was designed and built to measure the pressure drop in three pipes of 12.70, 19.05 and 25.40 mm. The water and air flow rates can be adjusted to control the mixture velocity and void fraction. The measurements are performed under constant water flow rate (CWF) by adding air to the water and constant total flow rate (CTF) in which the flow rates for both phases are changed to give same CTF. The drift-flux model is also used to predict the pressure drop for same cases. The present data is also compared with a number of empirical models from the literature. The results show that: i) the pressure drop increases with higher volumetric qualities for the cases of constant water flow rate but decreases for higher volumetric qualities of constant total flow rate due to the change in flow pattern. ii) The drift-flux model and homogenous model are the most suitable models for pressure drop prediction. (C) 2017 Elsevier Ltd. All rights reserved.9112012

    Medición de la concentración de radón (222Rn) y torón (220Rn) en diferentes plantas (vegetales) ubicadas en la ciudad de Sulaimania empleando el detector CR-39

    Get PDF
    Introduction: Radon is a radioactive gas released from the normaldecay of uranium in rocks and soil depending on local geology. Radioactive decay of uranium through radium produces radon. Materials and Methods: In the present work, seventeen plant (vegetables) samples collected from Sulaimania Governorate. The plants have been analyzed and examined to measure the level of radon (222Rn) and thoron (220Rn) using plastic track detector (CR-39) for evaluation of radon and thoron concentration in this region. Results and Discussion: The results indicated that the higher andlower radon concentration have been found in Halabjay-con, and inSulaimani-center, to be (119.72 Bq.m-3, 3.236 pCi/L), (54.36 Bq.m-3,1.469 pCi/L), respectively, and the higher and lower thoron concentration have been found in Qaladza and in Sulaimani-center, to be (733.66 Bq.m-3, 19.828 pCi/L), (227.33 Bq.m-3, 9.117 pCi/L), respectively. Radiation level compared with the standard level known by the EPA (4 pCi/L) and190 Bqm-3. The concentration of radon in all sample plants is less than international standard level 4(pCi/L)and190 (Bqm-3), therefore the human in safety. The average effective dose equivalent (EDE) of radon from plants determined was (7.2) μSv.y-1 for all the samples. This is lower than the normal value of (1.3) mSv.y-1 given by EPA. Conclusions: This study showed that the contamination in the plant (vegetables) is normal and is not considered a great radial dose for plants and consequently for humans

    An Investigation of Electrical Motor Parameters in a Sensorless Variable Speed Drive for Machine Fault Diagnosis

    Get PDF
    Motor current signature analysis (MCSA) is regarded as an effective technique for motor and its downstream equipment fault diagnostics. However, limited work has been carried out for motors based on a sensorless variable speed drive (VSD). This study focuses on investigation of mechanical fault detection and diagnosis using electrical signatures from a VSD system. An analytic analysis was conducted to show that the fault can induce sidebands in instantaneous current, voltage and power signals in the VSD system, rather than just the sideband in a drive without closed loop control. Then different degrees of tooth breakages in an industrial two-stage helical gearbox were experimentally studied. It has found that even though the measured signal is very noisy, common spectrum analysis can discriminate the small sidebands for the fault detection and diagnosis. However, it has found that the power signals resulted from the multiplication of the current and voltage can provide a better diagnostic result

    The Association of Prothrombin Gene Mutations and Cytomegalovirus Infection with Abortion Among Iraqi Women

    Get PDF
    يُصنف الإجهاض على أنه إنهاء الحمل الناجم عن فشل أو إزالة الجنين من الرحم قبل إتمام الحمل. هناك عوامل مختلفة ترتبط بالإجهاض منها الكائنات الحية الدقيقة والعوامل الوراثية. ان الفيروس المضخم للخلايا هو أحد مسببات العدوى الفيروسية الخلقية التي تصيب مجموعة واسعة من الأشخاص. يعتبر جين البروثرومبين (معرف الجين: 14061 في NCBI) أحد الأسباب الأساسية التي تؤدي إلى تخثر الدم ووظيفة الإجهاض، وبالتالي فإن الهدف من الدراسة هو اكتشاف وربط الفيروس المضخم للخلايا وطفرة جين البروثرومبين بالإجهاض من خلال الأساليب الجينية والمناعية.  تم جمع 5 مل من حجم الدم الكامل من خلال وخز الوريد وتم تقسيمها إلى أنبوبتين، أحداهما تحتوي على EDTA والأخرى دون (أنبوب عادي) من 74 امرأة لديهن تاريخ إجهاض كمجموعة مريضات و74 امرأة بدون سجل إجهاض مع واحد على الأقل من الخصوبة الناجحة كمجموعة تحكم. تُستخدم PCRs الخاصة بأليل لتضخيم مناطق الجينات باستخدام بادئات جينية تحتوي على تعدد أشكال جينات البروثرومبين.أظهرت النتائج الحالية أن أكبر خطر للإجهاض لوحظ في النساء المصابات بتفاعلية مصلية IgG في 65 امرأة مع تردد (87.8٪) وكان أقل معدل للإجهاض في إيجابية مصلية IgM في 3 نساء بمعدل تكرار (4.1٪) و6 (8.1٪).) كانت إيجابية لـ IgM-وIgG يشير إلى امتلاكهم عدوى قديمة وحديثة. علاوة على ذلك، تُستخدم PCRs الخاصة بالأليل لتضخيم تعدد الأشكال البروثرومبين G20201A. أظهرت نتيجة هذه الدراسة عدم وجود علاقة بين تكرار مستوى النمط الجيني للبروثرومبين والإجهاض في النساء المصابات بفيروس CMV. في حين أن هناك علاقة ارتباط ذات دلالة إحصائية بين مجموعات الأليلات A وG والإجهاض في النساء المصابات بفيروس CMV.Abortion is categorized as the termination of conception caused by the failure or removal of the embryo from the uterus before the conclusion of pregnancy. Microorganisms and genetic factors are two of the many factors associated with abortion. Cytomegalovirus is a widespread congenital virus infection pathogen that affects a wide variety of people. The prothrombin gene is one of the essential causes that trigger blood clotting and the function of abortion women, therefore the aim of the study is to detect and associate Cytomegalovirus and prothrombin gene mutation (Gene ID: 14061 in NCBI) with abortion through genetic and immunological methods. Five ml of whole blood was collected from an intravenous puncture and divided into two tubes, one with EDTA and one without (plain tube) from 74 women with an abortion history as a patient group and 74 women without an abortion record who had at least one successful fertility as a control group. Allele-specific PCRs are used to amplify gene regions with genetic primers containing prothrombin gene polymorphisms. Current results have shown the greatest risk of abortion was observed in women patients with IgG seropositivity in 65 women with frequency (87.8%) and the lowest rate of abortion was in IgM seropositivity in 3 women with frequency (4.1%) and 6 (8.1%) were positive for IgM-and IgG indicating they have both an old and recent infections. Furthermore, allele-specific PCRs are used to amplify prothrombin G20201A polymorphism. The result of this study demonstrated there is no association between prothrombin genotype level frequency and abortion in CMV-infected women. While, there is a highly significant association between A and G Alleles combinations and abortion in CMV-infected women

    Crystal plasticity finite element simulations using discrete Fourier transforms

    Get PDF
    Crystallographic texture and its evolution are known to be major sources of anisotropy in polycrystalline metals. Highly simplified phenomenological models cannot usually provide reliable predictions of the materials anisotropy under complex deformation paths, and lack the fidelity needed to optimize the microstructure and mechanical properties during the production process. On the other hand, physics-based models such as crystal plasticity theories have demonstrated remarkable success in predicting the anisotropic mechanical response in polycrystalline metals and the evolution of underlying texture in finite plastic deformation. However, the integration of crystal plasticity models with finite element (FE) simulations tools (called CPFEM) is extremely computationally expensive, and has not been adopted broadly by the advanced materials development community. The current dissertation has mainly focused on addressing the challenges associated with integrating the recently developed spectral database approach with a commercial FE tool to permit computationally efficient simulations of heterogeneous deformations using crystal plasticity theories. More specifically, the spectral database approach to crystal plasticity solutions was successfully integrated with the implicit version of the FE package ABAQUS through a user materials subroutine, UMAT, to conduct more efficient CPFEM simulations on both fcc and bcc polycrystalline materials. It is observed that implementing the crystal plasticity spectral database in a FE code produced excellent predictions similar to the classical CPFEM, but at a significantly faster computational speed. Furthermore, an important application of the CPFEM for the extraction of crystal level plasticity parameters in multiphase materials has been demonstrated in this dissertation. More specifically, CPFEM along with a recently developed data analysis approach for spherical nanoindentation and Orientation Imaging Microscopy (OIM) have been used to extract the critical resolved shear stress of the ferrite phase in dual phase steels. This new methodology offers a novel efficient tool for the extraction of crystal level hardening parameters in any single or multiphase materials.Ph.D

    Solution of Multi-order Fractional Differential Equation Based on Conformable Derivative by Shifted Legendre Polynomial

    Get PDF
    The aim of this article is the way for finding approximation solution of multi-order fractional differential equation with conformable sense with use approximated function by shifted Legendre polynomial, the method is easy and powerful for get our results of the linear and non-linear equation, the background idea behind this method is finding system of algebra after achieving messing variable is that mean obtain approximate solution, a few examples illustrates for presented how much our method is capable

    Determination of Aflatoxin Levels in Groundnuts: A Comparative Study between Domestic and Imported Seed Supplies in Libya

    Get PDF
    The production of high-quality seeds presents a significant challenge for small-scale farmers in Libya. These farmers often face difficulties with storing their own seeds, encountering issues such as storage fungi and aflatoxin contamination. Aflatoxins, known to cause various human and animal health problems, are prevalent contaminants in groundnut seeds during storage, primarily produced by Aspergillusflavus and Aspergillusparasiticus fungi. This study compares aflatoxin levels between locally sourced and imported groundnut seeds. Samples were procured from the local market in Tripoli, Libya, and aflatoxins were extracted and identified using thin-layer chromatography (TLC) with Silica gel. The findings reveal higher aflatoxin levels in local samples compared to imported groundnut seeds. Various factors influence aflatoxin levels, and the detected levels surpass European Union standards. To address this, regulatory measures or awareness campaigns among local farmers are recommended to ensure quality and sustainability in groundnut cultivation in Libya

    Device–to-Device Association Algorithm for Optimal Neighbour Selection and Channel Sharing in 5G Cellular Networks

    Get PDF
    The integration of device-to-device (D2D) communication in 5G cellular networks has generated the possibility of multiple transmission modes in a single cell. This has motivated scholars to investigate different mode selection and D2D association algorithms that guarantee the selection of proper transmission mode. However, the complexity of algorithms and tractability of devices in the cell are still remarkably challenging. This paper, therefore, presents a utility based D2D association algorithm that ensures optimal neighbour selection by using numerical linear algebra to minimize computational complexity. Simulation results show that the minimum utility based D2D association increases the expected values of attached devices by 6% and 10% compared to the relative distance and maximum utility based D2D associations, respectively. Alternatively, the throughput expectation increases by 2.5% and 4% compared to the relative distance and maximum utility based D2D associations, respectively. Keywords: Cooperative Communication; D2D, Mode Selection; Relay-assisted; Traffic Overloa
    corecore