bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of some of the physical variables of a metal-based system using the powder method
Authors: Salih Eman J. , Allah Sabah Mahmoud Aman , Darweesh Salih Y. , Mohammed Hussein A.
Published: September 2021

Some variables that in turn help improve the properties of copper, whether mechanical or physical, were studied. Copper was reinforced with carbide with excellent properties from WC and with different volumetric enhancement ratios (0,1.5,3,4.5,6) %. The powders were mixed and milled for a two-hour time, as the samples were pressed at (5) tons for a time of one minute, after which the prepared samples appeared at 950°C and for a time only two hours, various tests were conducted on the samples for the purpose of studying their physical and compositional properties and included a diffraction examination X-ray, real and apparent porosity, real and apparent density, compressive strength. The results were encouraging and gave the best values after sintering and at a 6% WC boost, if the minimum true porosity was 13.31%, while the apparent porosity was 9.22%, while the real density value was10.72g/cm3, and the highest apparent density was 11.22g/cm3. The radial compressive strength value is 132.7MPa.
Preparation and characterization of structural and optical properties of CdS thin film spin coating prepared
Authors: Sami Riyadh , Ghazai Alaa J.
Published: September 2021

In this paper, a Cadmium sulphide (CdS) nanocrystal thin film has been prepared on glass substrate using the sol-gel method. As deposit and effect annealing films at an annealing temperature of 500°C for 1hour were investigated and characterized. The characterization of prepared films included, structural properties using X-ray diffraction (XRD), Scanning electron microscope (SEM), Atomic force microscope (AFM), and optical Properties using UV-Visible measurement. based on XRD results the annealing reason increase in peak intensity due to the improvement in the crystallinity and the crystalline size decreased with increasing the annealing temperature in regrading of preferred diffraction peak (111) at 2 θ =26 to be fourth more, this indicated a formation of cubic structure of the CdS nanocrystalline thin films as the predominant phase. When the dislocation density and strain initially decreased with increasing the annealing temperature due to the improvement of crystallization. SEM images revealed that the films have Nano sphere-based or cluster-like shape and the structure uniformly grown on the substrate have been observed with annealing temperature. Besides, the roughness, root mean square(RMS), and average diameter. decreased while the grain size increased with annealing temperature. The optical properties showed that the films have low absorption over the visible region and it’s decreasing the annealing temperature which makes the CdS is a promising material for optoelectronic application. The energy gap increases with a decrease in the size of the crystallites, while an energy gap value is somewhat larger than the typical value of bulk CdS. This may be due to the quantum confinement effect due to the nanometer crystallite size of the cadmium sulphide thin film. The first section in your paper.
Study of Nuclear Radius and Back bending phenomenon of20-30Mg Isotopes in sdpn Model Space
Authors: Obeed Fatema H.
Published: September 2021

In present work, many parameters have been computed using NuShellX@ MSU code for ground state bands of20-30Mg isotopes. These parameters were root mean square of nuclear radius, major and minor of ellipsoid axises (a and b), as well as to the different between them(ΔR) deformation parameters (β2, δ), intrinsic quadrupole moment(Q0) and back bending phenomenon. Model space(sdpn) of (0d3/2,0d5/2and 1s1/2) for protons and neutrons orbits and cwhcdpn interaction have been used to calculate above parameters. Effective charge of Bohr - Mottelson model has been used in this work. The results showed an brilliant agree with the obtainable investigational results all isotopes in this study. Also, the back bending phenomenon was well evident in our results for all isotopes used under study. In these calculations, new values have been theoretically designated for most parameters which were previously unknown in experimental information.
The Effectiveness of the Finite Differences Method on Physical and Medical Images Based on a Heat Diffusion Equation
Authors: Rasheed Mohammed , Ali Ali Hassan , Alabdali Osama , Shihab Suha , Rashid Ahmed , Rashid Taha , Abed Hamad Saad Hussein
Published: September 2021

In this paper, we study the influence of applying the well-known finite differences method on medical and physical images. These images will be used as coefficients in the steps of the solution after the images being imported and converted to arrays. The aim of the study is to show and analyze the changes that could happen to images for the sake of an enhancement. Experiments of one dimension and two dimensions will be illustrated by applying the explicit and the implicit methods using MATLAB to explain the way of how these methods affect images. Furthermore, we will study and measure the quality of the proposed images in each phase of the experiments using statistical metrics such as PSNR (Peak Signal to Noise Ratio), MSE (Mean Squared Error), MD (Maximum Difference) and some other statistical metrics.
The Proximity Congested Set and not Congested Set
Authors: Talkany Y K AL , Al-Swidi L A
Published: September 2021

this paper includes a study related to the concept of proximity congested sets and proximity not congested sets in i-topological proximity spaces which were defined using two concepts are the i-closure concept and nested set and then utilized it in studying a new type of concept namely cpc-congested set, cp-congested set, pc-congested set. Some of the characteristics and theories of these new sets were presented in this paper.
High-order solution of Generalized Burgers–Fisher Equation using compact finite difference and DIRK methods
Authors: Pirdawood Mardan A. , Sabawi Younis A.
Published: September 2021

The main goal of this paper is to developed a high-order and accurate method for the solution of one-dimensional of generalized Burgers-Fisher with Numman boundary conditions. We combined between a fourth-order compact finite difference scheme for spatial part with diagonal implicit Runge Kutta scheme in temporal part. In addition, we discretized boundary points by using a compact finite difference scheme in terms of fourth order accuracy. This combine leads to ordinary differential equation which will take full advantage of method of line (MOL). Some numerical experiments presented to show that the combination give an accurate and reliable for solving the generalized Burgers-Fisher problems.
Development a new conjugate gradient algorithm for improvement feedforward artificial neural networks for predicting the numbers of the Iraqi
Authors: alfahady Neaam H. , Abbo Khalil K. , Nori Mahmood Edrees M.
Published: September 2021

a conjugate gradient method has been proposed for use in the training of Artificial Neural Networks with the feedforward technique. The proposed method demonstrated that the proposed CG method is accurate in predicting the numbers of the Iraqi population, the Our numerical results where very close to the exact solution of Tomas Malthose Model.
Certain Geometric Properties of Meromorphic Functions Defined by a New Linear Differential Operator
Authors: Hameed Mustafa I. , Shihab Buthyna Najad , Jassim Kassim Abdulhameed
Published: September 2021

In the present paper, we investigate a new linear operator through the Hadamard product between the fundamental hypergeometric function and the Mittag Leffler function. Furthermore, the geometric properties of a new meromorphic function subclass will be investigated.
NTRsh: A New Secure Variant of NTRUEncrypt Based on Tripternion Algebra
Authors: shahhadi S H , Yassein H R
Published: September 2021

Since cryptography relied on mathematical theories and applications of computer science, mathematical algorithms are built with high difficulty. In this paper, we make an improvement and modification NTRU cryptosystem called NTRSH by using a new tripternion algebra and changing the mathematical structure for public and private keys, as well as for text encryption and decryption to obtain more and higher security.
Semi-Implicit and Explicit Runge Kutta Methods for Stiff Ordinary Differential Equations
Authors: Sabawi Younis A. , Pirdawood Mardan A. , Khalaf Anas D.
Published: September 2021

In this work, we study theA[α] – stability of the additive methods of Runge- Kutta kind of orders ranging from 2 up to 4 that will be applied for determining some stiff nonlinear system of the ODEs. Moreover, we find the stability function for the additive Runge-Kutta method and some methods of this type of order 2,3, and 4. Where the method (A,B1) is A-stable and semi-implicit and method (A,B2) is explicit. Furthermore, the stiff term is managed by the semi-implicit Runge-Kutta method while no stiff term is treated by the explicit Runge Kutta method. Those methods are suitable for solving chemical reactions problems that include stiff and non-stiff terms.
Theory and applications of Marshall Olkin Marshall Olkin Weibull distribution
Authors: Al-Noor N H , Khaleel M A , Mohammed G J
Published: September 2021

In probability theory generalizing distribution is an important area. Several distributions are inappropriate for data modeling, either symmetrical, semi-symmetrical, or heavily skewed. In this paper, a new compound distribution with four parameters called Marshall Olkin Marshall Olkin Weibull (MOMOWe) is introduced. Several important statistical properties of new distribution were studied and examined. The estimation of unknown four parameters was carried out according to the maximum likelihood estimation method. The flexibility of MOMOWe distribution is demonstrated by the adoption of two real datasets (semi-symmetric and right-skewed) with different information fitting criteria. Such flexibility allows using the new distribution in various application areas.
Magnetohydrodynamics Peristaltic Flow of a Couple- Stress for a Jeffrey Fluid through a Flexible Porous Medium
Authors: Al-Khafajy Dheia G. Salih , Al-Waily Saif Razzaq Mohsin
Published: September 2021

The topic of this paper is the peristaltic motion of a non-Newtonian Jeffrey fluid with couple stress across a porous medium inside a horizontal conduit. The unit is strained by a uniform magnetic field. It is taken into account the effects of viscous dissipation, internal heat generation, and radiation. This approach solves the equations of momentum, temperature, and velocity. The numerical formulas for axial velocity, temperature, and velocity are obtained as functions of the physical parameters of the problem. Numerical calculations, as well as the effects of temperature and magnetic field on the velocity equation, were conducted for this formula, and the results were shown on the channel wall. The results of the problem’s physical parameters on this formula are discussed numerically and graphically in a series of statistics.
An efficient algorithm for st-Connected Vertex Separator problem
Authors: Younis Althoby Haeder
Published: September 2021

In this paper, we give some basic notions concerning the st-connected vertex separator problem(st-CVS problem), then we give mathematical formula for st-CVS problem, then some special cases on some types of graphs, after then introduce an integer programming formulations for this problem. Also, we introduce a heuristic to solve this problem.
A Review Over Panoramic Image Stitching Techniques
Authors: Abbadi Nidhal K. EL , Al Hassani Safaa Alwan , Abdulkhaleq Ali Hussein
Published: September 2021

Using digital images at present are increased rapidly in many fields such as in solving big problems, with the extraordinary appearance of them in all areas of life, in medicine, agriculture, industry, the Internet, and others, where their use is extensive and is considered a source of information for technological progress. One of the important use is stitching the images, also called mosaic images. The stitching images means a grouping of images for the same sense with the overlapping areas to be a panoramic image of high resolution and wide width. With the modification and development of the algorithms used in this field in recent years, it has become one of the essential branches of image processing. There are many applications of stitching, used in maps and satellites, knowledge and positioning, etc. So this summary article will provide a set of image stitching techniques and investigate its use in terms of advantages, disadvantages, and accuracy for each one of them with comparative studies of several research papers in this field for the period of years (2017 – 2020). Therefore, this article may be useful for researchers working in this field to benefit and develop stitching algorithms in terms of discovering features and matching them to create a useful, problem-free, and high-resolution panoramic image.
Hiding Region of Interest in Image using Fuzzy Logic
Authors: Kharofa Shahla Hazim Ahmed , Al-khayyat Ali Tariq Kalil
Published: September 2021

In this research, a new method for hiding image has been proposed. The proposed method relied on hiding the region of interest in the image by specifying it using fuzzy logic. Images play a large and important role in several areas. Therefore, The more important the image, the greater the need to protect and preserve it. In this research, the work was divided into two parts, the first part represents the sending side and in it the face area is defined as an important region in the image and hidden then, while the second part, represents the receiving side and in it the hidden image is received and unhide. Fuzzy logic was used in the process. The proposed algorithm provide security to the images being transmitted. Matlab language was use to perform this work.
Diabetic Retinopathy Diagnosis based on Convolutional Neural Network
Authors: Abed Mohammed hamzah , Muhammed Lamia Abed Noor , Toman Sarah Hussein
Published: September 2021

Diabetic Retinopathy DR is a popular disease for many people as a result of age or the diabetic, as a result, it can cause blindness. therefore, diagnosis of this disease especially in the early time can prevent its effect for a lot of patients. To achieve this diagnosis, eye retina must be examined continuously. Therefore, computer-aided tools can be used in the field based on computer vision techniques. Different works have been performed using various machine learning techniques. Convolutional Neural Network is one of the promise methods, so it was for Diabetic Retinopathy detection in this paper. Also, the proposed work contains visual enhancement in the pre-processing phase, then the CNN model is trained to be able for recognition and classification phase, to diagnosis the healthy and unhealthy retina image. Three public dataset DiaretDB0, DiaretDBl and DrimDB were used in practical testing. The implementation of this work based on Matlab-R2019a, deep learning toolbox and deep network designer to design the architecture of the convolutional neural network and train it. The results were evaluated to different metrics; accuracy is one of them. The best accuracy that was achieved: for DiaretDB0 is 100%, DiaretDB1 is 99.495% and DrimDB is 97.55%.
Default on a credit prediction using decision tree and ensemble learning techniques
Authors: Mesri Khitam , Tahseen Israa , Ogla Raheem
Published: September 2021

Due to the high importance of credit risk management and the prediction of the default on a credit loan in banks in recent years in most developed countries. This research experimented with three machine learning algorithms which are decision tree and ensemble techniques based on a decision tree-like random forest which is bootstrap aggregation machine learning model and adaptive boosting is a boosting machine learning model. All models were used to perform a binary classification to classify the clients into trusted clients who would pay back the debts who are creditable and a none trusted clients who won’t pay the debts In the time which are who are not creditable. All the models gave nearly the same results based on the selected performance measures which are precision, recall, and f1 measure. There was no significant change when they performed on a real class imbalanced dataset of the default credit card clients of Taiwan.
The Recent Studies Utilizing Computer Technologies for Covid 19 Transmission, Diagnosis and Infection Control
Authors: Muthana Rasha , Ahmed Nora , Al shareefi Asaad
Published: September 2021

In March 2020, the extreme serious respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes COVID-19, was declared a universal pandemic. It is an RNA-type virus that affects humans and animals and causes a wide range of respiratory infections. It also leads to human pneumonia. The development of the virus recognition system relied heavily on computer programs. Numerous experiments and research have been conducted in computer science in order to identify any treatments and explore the effects of the disease. As a result, the most important research and strategies for detecting covid19 will be outlined in this article, to use them in the future to stop this global epidemic.
Synthesis and spectral characterization of new azo dye derived from benzimidazole and its complexation with selected transition metal ions
Authors: Al-adilee K J , Hatem B A , Hatem O A
Published: September 2021

The preparation and spectral characterisation of 2-[6-(benzimidazolylazo)] as an organic heterocyclic azo dye compound containing benzimidazole. The reaction of benzimidazole diazoniumbromid with 2,4-dibromo phenol in alkaline alcoholic solution yielded -2,4-dibromo phenol (BIADBrP). Spectral analyses have been used to study the structure of the azo dye ligand such as H1NMR, mass spectrum,IR, UV-Vis and element analysis. New six complexes with CO(III), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) ions were prepared and identification by several physiochemical techniques; such as C.H.N element, magnatic susceptibility, atom absorption, molar conductivity, IR and electronic spectra. The used techniques showed the formation of all complexes 1:2 [M:L] complexes and suggested octahedral geometry with d2sp3 hybridization of Co(III) and sp3d2 with residulechelat complexes. The coordination number of the metal ion is found to be six with binding through the phenolate O, azo N3 and with the imidazole N3 atom. The stability, geometrical, and electrical features of metal complexes have also been studied theoretically. The energy levels of the ligand and metal complexes’ high occupied molecular orbital HOMO and low unoccupied molecular orbital LUMO were used to compute electrochemical potential, electrophilicity index, and chemical hardness.
Simulation of Charge Sensitive Preamplifier to improve Nuclear Pulse detecting using Multisim Software
Authors: Atiea Hassanein M. , Rashid Jabbar M.
Published: September 2021

Simulation of Charge Sensitive Preamplifier (CSP) to improve Nuclear Pulse detecting Circuit has been carried on Multisim Software. Multisim Software is a great software that creates the best user-friendly simulation environment for professors, engineers, and students. We can simulate electronic circuits and build prototypes for Printed Circuit Boards (PCBs). In this paper, we have simulated CSP Circuit in two ways. Firstly, by using a pulsed voltage source. Secondly, by using a waveform generator. We have analyzed the behavior of the CSP Circuit with various rise times. The output waveforms have been observed on the oscilloscope.
High Order Inverse Radial Lens Distortion
Authors: Hamed Baidaa Khalifa , Hamad Rihab Khalifah , Hassonny Hussien Ali
Published: September 2021

Lens distortion is one of the highest elements affecting camera calibration. In this paper, a new improved algorithm for calculating the inverse of the best radial distortion model is presented. The presented method provides a model of reverse radial distortion. The method involves lens of focal length (190mm) with a Sony G camera, and calibrating them using Zhang method which entails a chessboard pattern to be detected from several positions, and an exact formula to calculate the inverse radial distortion.

The results show that the highest order radial distortion is the better model to be reverse, it was shown that the 8th order radial distortion is the best model which contain a lowest value of distortion can be acquired after a number of iterations about 1.009842932 × 10-24, and this is the best value can be acquired without losing the accuracy, which produces low distortion performs as pincushion distortion. The new improved algorithm displays a good performance in obtaining least value for distortion coefficient.
The effect of reinforcing with fibers and nanomaterials on the electrical properties of composite materials
Authors: Fadel Dawood S. , Rajab Mustafa A. , Ali Amir Khalaf
Published: September 2021

Technological development depends mainly on the progress of materials so that materials must be able to withstand service conditions. Accordingly, we always move towards composite materials, by combining two or more materials and often have different properties, so that the two materials work together to give unique composite properties. The aim of this study is to study the electrical properties represented by insulation and electrical conductivity of composite materials (including epoxy (95%) and phenol formaldehyde (5%)) supported by graphite nanoparticles and glass fibers.
Development the Regularization Computing Method for Solving Boundary Value Problem to Heat Equation in the Composite Materials
Authors: Al-Mahdawi H.K.
Published: September 2021

In this paper, the heat conduction equation for composite materials posed and solved. The inverse Boundary Value Problem (BVP) described and solved. By studying and solving the direct problem for the heat equation in composite materials, we can determine the function spaces and solve the inverse problem. The Sturm-Liouville method was used to solve this problem by reduce it to the integral equation for first kind. The Boundary value problem can be formulated as an integral first kind equations. The discretization algorithm applied to reformulated the problem as linear operator problem as matrix and vectors form. Then, Lavrentev regularization method used to find the approximation solution.
A study on the optical properties of the PMMA polymer doped with some semi metal dioxides nanoparticles
Authors: Jasim Khalid Mahdi , Ali Riyed Naje. , Al-Hamdani Ali H.
Published: September 2021

This work on a compound polymer PMMA doped with some semi-metal oxides nanoparticles (SiO2, TiO2) NPs, intended to be utilized in corrective Contact Lenses. For this purpose the optical properties of the PMMA compound (PMMA+2%SiO2, PMMA+2%TiO2, and PMMA+1%SiO2+1%TiO2) NPs were measured and calculated to get the proper refractive indices and dispersion properties (Abbe number) for these compounds for optical design optimization.
Preparing Nano Material As Introduction To Network
Authors: Muslm Israa Falih
Published: September 2021

Carbon nanotube technology has been used in many fields, and among the new applications of nanotechnology, the carbon nanotube is composed of ink, which is an ink that has been developed By Dr. Lee Jin Wong of the Korea Electrical Technology Research Institute. This technology is very sophisticated and can be applied This technology is applied to a variety of fields, including touch screens and foldable displays, although Dr. Lee may He chose the field of touch screens, due to the lack of technology for permanent coating of plastic surfaces and the development A carbon tube of ink marked the beginning of a new journey of incredible excellence in the field of nanotechnology That would be a huge technological revolution
Studying the effect of using a mixture (synthetic polymer: natural polymer) on the rheological properties of asphalt
Authors: Abass Mahmoud F. , Hamdoon Ammar A.
Published: September 2021

The rheological modification of asphalt is currently the most important concern of workers in this field, whether a person is a chemist or a civil engineering worker. Several methods are used in rheological modulation processes. The rheological modification with polymeric materials is still the one that has taken the largest space in this field In this study, we dealt with the rheological modulation processes with polymeric mixtures. It used a mixture of materials that have proven effective in the field of rheological modulation and others that did not give the desired results. In this study, a mixture of a synthetic polymer, which is ethylpene vinyl acetate, and a natural polymer, which is wood, were used. Use this mixture with different weights of both polymers and for a total of 1 gram. The asphalt was treated with the above mixture with 1% by weight of sulfur at 180 ° C for a period of one hour The rheological properties of the modified samples were measured, which included measuring the ductility, penetration and softining point as well as calculating the penetration index coefficient and the percentage of the separated asphaltens.

After that, the best sample obtained from the above treatment was taken and several interactions were conducted on it in order to determine each of: The optimum percentage of sulfur, The optimum temperature for modification process, The optimal time to perform the rheological modification processes, The effect of the addition process sequences on the properties of the axis asphalt was also studied. After that, the best sample obtained from this study was taken and was measured (Marshal, chemical immersion and as well as studying the effect of aging on this sample). The study gives good results in the field of asphalt resistance to the deformation processes that were carried out on it.
Studying the effect of laser irradiation with different wavelength on absorbance of normal human blood
Authors: Mohammed Raneem , abd-aldaim Wajeha , Hassan Sadiq
Published: September 2021

The optical effects of laser irradiation on whole human blood were studied. The normal blood samples were taken from healthy persons and the blood samples were exposed to laser beam. Three wavelengths of continuous wave (CW) for diode pumped solid state

lasers (DPSSL S) were used to irradiate the blood samples. The wavelengths are (632 nm, 532 nm,473nm and405 nm ) and output varied between ( 3.9, 50,20 and 4.5) mW respectively. The laser exposure time fixed between (5 and 10 ) min for each wavelength. Laser radiation has a great role in the absorption properties of the normal human blood after being compered with absorption spectrum of a non-irradiated sample.
Determination of the X-ray Scattering Cross Section and the imaginary part of the form factor of Nickel
Authors: Mazban Shifaa , Ali Mohsin Hasan
Published: September 2021

In this paper x-ray mass attenuation coefficients of nickel were measured with precision between 0.2% and 0.5% for four characteristic wavelengths: copper and molybdenum K lines. The mass photoelectric absorption coefficients were determined by subtracting the calculated coherent and incoherent scattering from the total scattering and the values of measured attenuation coefficients. The values of the imaginary component of atomic scattering factor for x-ray in nickel were determined from the difference between the values of measured attenuation coefficients and theoretical calculations, it is shown that In the low energy at ω ≪ ωe, and the high energy at ω ≫ ωe, the imaginary component approximately is zero, and the electrons are so tightly bound to the atom. In the region ω ˜ ωe where the imaginary component of the scattering is dominate and the electron become highly absorbing. There was good agreement between the values of the imaginary component of atomic scattering factor has been found and the theoretical FFAST (Chantler, 1995) tabulated values..
Effect of Laser Parameters on the Characteristics and Stability of Ag NPs Produced by Laser Ablation in Stationary Conditions
Authors: Baneen M.H. , Baiee Raid M.
Published: September 2021

The effect of laser ablation parameters on the size and stability of synthesized silver nanoparticles (Ag NPs) by laser ablation in deionised water was investigated. The results showed that the selected laser parameters (laser pulse wavelength and laser fluence) and ablation of the target in a fixed beam position had a direct effect on the size and size distribution of Ag NPs. The stability of all Ag nanoparticle samples prepared in different laser parameters has been studied. All the samples of Ag NPs presented remarkable long-term stability up to two months.
Assessment of Water Quality for Tigris and Euphrates Water within Iraqi Borders
Authors: Mohammed Muhannad Kh. , Naji Mohammed Sh. , Ameen Nabeel H. , Karkosh Huda N.
Published: September 2021

The Tigris and Euphrates Rivers represent the main sources of water in Iraq. The recent water crisis in the region has prompted the necessity of assessing the quality of the rivers water. Water quality from 33 locations along the Tigris and Euphrates Rivers were investigated in November 2020, December 2020, January 2021, and February 2021 to test 3 water quality chemical parameters in the selected stations along the Tigris and Euphrates Rivers. These parameters are pH, TDS and EC. The variations of total dissolved solids (TDS) along the Tigris and Euphrates Rivers in the survey period ranged from 100 to 5057 ppm, and the average value of TDS concentration was 862.3 ppm. For pH, the values measured during the survey period ranged from 6.4 to 7.6, with an average value of 7.2. The average electrical conductivity measured in Tigris and Euphrates Rivers during the survey period was 1717.6 μS, ranged from 230 to 9870 μS. The weighted arithmetic method was applied to compute the water quality index (WQI) for the overall sampling locations along the whole length of the Tigris and Euphrates Rivers within the Iraqi borders. The results showed that the estimated water quality index (17.28) was within the “Excellent” range (< 50).
Characterization Studying Optical Fiber Chemical Sensor for Different Applications
Authors: Abdul-Jabbar Nisreen , Kadhim Shehab A. , Jabor Ashwak A. , Lateef Alaa Th.
Published: September 2021

In this work, the optical fiber chemical sensor had been introduced based on the Fabry- Perot interferometer technique. Single-mode fibers were used with different diameters (125, 60, 50) μm. Chemical etching technology is used to reduce fiber diameters. Sensor heads were immersed in chlorophyll dye with different concentrations. The submitted sensor shows good sensitivity and linearity towards the variation in the chemical dye concentration. Both the peak wavelength and peak power were changes. The higher wavelength and power sensitivities were higher for the sensors with a smaller diameter. This technique could be very useful in medicine, drug pharmaceutical and food industries applications.
A simple, step-by-step approach for the preparation of MoO3@g-C3N4 nanocomposite
Authors: Mohammed Amina H. , Yousif Qahtan.A.
Published: September 2021

We present a simple step-by-step method for the preparation of MoO3@g-C3N4 nanocomposite. Several approaches were used to prepare and characterize the nanocomposite with a weight ratio of MoO3 (0.075). X-ray diffraction measurements have revealed The primary peaks of MoO3 at 13.14°, 23.74°, 26.07°, 27.71°, 29.98°, and 39.33° correspond to the iq (020), (110), (040), (120), (021), and (060) planes, and the g-C3N4 appearing at 27.49° and 12.94° corresponds to the (002) and (100) planes in the MoO3@g-C3N4 nanocomposite. The specific bands for the as-prepared nanocomposite were revealed by Fourier-transform infrared. With the H3 hysteresis loops, the BET isotherm and the BJH technique produced results compatible with Type IV. Furthermore, the results indicated the effective change in surface area, pore-volume, and pore diameter values were larger in the MoO3@g-C3N4 nanocomposite. Diffuse spectroscopy of reflection data revealed more information about the changes that occurred when MoO3 was loaded on the g-C3N4 layers to shift the spectrum to the red extent while decreasing the band gap to 2.63 eV. Furthermore, field emission electron spectroscopy has proven the synthesis of nanocomposite by a dramatic change in the morphological surface as well as a change in the composition of elements that have been demonstrated using the energy-dispersive X-ray spectroscopy methodology. This discovery has improved the form and structure of the MoO3@g-C3N4 nanocomposite
Operational Metrics for an Offshore Wind Farm & Their Relation to Turbine Access Restrictions and Position in the Array
Authors: Anderson F , Dawid R , García Cava D , McMillan D
Published: September 2021

This study explores operations & maintenance requirements for offshore wind turbines. It does so by calculating performance, reliability and maintenance metrics from an operational database provided by a large offshore wind farm. Distributions of number of repairs and repair times per turbine are shared, as well as number of visits. A focus is placed on the effect of tidal access restrictions and position in the array by comparing clusters of turbines within the wind farm. It was found that tidal access restrictions lead to an increase in mean time to repair of 16%, and 0.22% decrease in technical availability. Turbines in the first few rows with reference to the prominent wind direction experience more minor failures on average, while those constantly operating in the wake of others are characterised by more major failures, and therefore a higher mean time to repair.
Offshore Wind: Employment and value creation of EPCI exports in Norway
Authors: Rocha Aponte F , Andersen T , Nørstebø V S , Uggen K T , Bjelle E L , Wiebe K S
Published: September 2021

The objective of this study is to investigate the value creation potential and the employment effects for the offshore wind engineering, procurement, construction and installation (EPCI) sector in Norway up to 2030 considering multiple scenarios. We perform our analysis using a macro-econometric input-output model that allows to observe how changes in one sector affects the remaining sectors of the economy. To highlight the uncertain nature of some of the outlooks and industry inputs for an emerging sector, several scenarios will be investigated. By providing information about net employment and value creation effects per sector, policy makers can implement appropriate measures to maximize the potential posed by the offshore wind industry. Furthermore, measures can be taken to mitigate any potential negative effects that the energy transition can have.
Predictive Capability of WRF Cycling 3DVAR: LiDAR Assimilation at FINO1
Authors: Bakhoday-Paskyabi Mostafa , Flügge Martin
Published: September 2021

In this study, we assess tentatively the predictive capability of the Weather Research and Forecasting (WRF) model and its Three-Dimensional Variational (3DVAR) system. We study the impact of LiDAR data assimilation on predictions of wind speed and direction. The simulation domain covers the German wind energy research platform FINO1 in the Southern North Sea, at which the LiDAR data were recorded. The results demonstrate the significance of applying the LiDAR Data Assimilation (DA) with a short assimilation interval (1-hour) to improve the wind prediction and the temporal and spatial representation of low level jet events, compared with an experiment without DA. Furthermore, we briefly examine the impacts of data assimilation cycle length on predictive performance of the DA system, and spatial variability of wind speed over the study area at a height of 250 m.
Presentation and validation of a simulation environment for floating lidar systems
Authors: Bischoff O. , Wolken-Möhlmann G. , Cheng P. W.
Published: September 2021

In recent years, floating lidar systems (FLS) have developed into a fully-fledged and accepted measuring instrument for determining and surveying wind conditions in the offshore sector. FLS are currently primarily used for wind resource assessment purposes before the construction phase of an offshore wind farm. That is why a precise knowledge of the measurement accuracy or uncertainty of the FLS for different wind and wave conditions is very important. The lack of knowledge could be mitigated with a simulation tool for FLS of different types and for variable wind and wave conditions. Within this paper we present an approach for such a simulation framework for FLS and the process for validating this simulation environment using data from an offshore measurement campaign. The data used for the validation include data from one FLS and two reference measurement systems (measuring mast and fixed lidar).
Experimental study on the effect of second order wavemaker theory on the response of a flexible large diameter monopile in irregular sea
Authors: Dadmarzi F H , Tonnel M , Thys M , Bachynski-Polić E E , Kristiansen T
Published: September 2021

Motivated by the need for larger offshore wind turbines, large diameter monopile foundations are being developed. To ensure safe design, there is a need for model testing and validation of hydrodynamic load models. Scaled model tests with a piston-type wavemaker commonly apply first order wavemaker theory for irregular waves. This approach results in the generation of second (and higher) order spurious (also known as parasitic) free waves in the tank. In this study, the effect of superharmonic spurious waves on the response of a monopile with eigenfrequency close to three times the wave peak frequency is examined experimentally. The bending moment response statistics are not found to be significantly affected by the wavemaker correction. Different wave breaking patterns are observed for individual events, but our results do not indicate any clear relation between breaking waves and the wave generation technique.
Wind farm set point optimization with surrogate models for load and power output targets
Authors: Dimitrov Nikolay , Natarajan Anand
Published: September 2021

This study presents a methodology for wind farm set point optimization, which allows including both loads and power output as optimization criteria. The primary control strategy investigated involves de-rating of individual turbines in the wind farm. The optimal de-rating level of each individual turbine is determined by using accurate and computationally efficient surrogate models, mapping the dependency between the choice of de-rating strategy for a given turbine and the load and power outputs of downwind turbines. A case study based on the Lillgrund offshore wind farm shows that for specific wind directions with strong wake interactions, it may be possible to achieve a net gain in power output in the order of 5% at specific mean wind speeds. Alternatively, maintaining nominal power output but optimizing the load distribution could lead to substantial fatigue load reductions.
Estimation of Wear and Lifetime for an Improved Turbine Operation
Authors: Durstewitz M , Rehwald F , Wick W
Published: September 2021

Design, construction and certification of wind turbines (WT) generally target a lifetime of at least twenty years. Depending on the specified design criteria in comparison with the’real’ conditions on site lifetime may fall below or pass over the design lifetime targets. After installation and during operation WT continuously suffer from incremental damage due to loads, fatigue and the continuous exposure to the physical environment and operating conditions. The initially inherent wear reserve of the WT or its components permanently decreases until it finally reaches predefined safety margins or the occurrence of premature component failure. The objective of the work is to identify quantifiable wear-out metrics and to deduce information on lifetime issues in order to optimise WT operation. The method divides into a simplified approach explaining the general concept and its implementation and adaption from design to in-situ conditions. Furthermore, the methodology is transferred to a component-specific level, namely generator windings, in order to evaluate the general suitability for non-mechanical load exposures. Finally, economic issues including an economic optimisation strategy considering previously calculated wear-out figures complete the work.
Comparing the Aerodynamic Performance of Floating Offshore Wind Turbines with Optimised and Linearised Blades
Authors: Fenech E. , Sant T.
Published: September 2021

Wind turbine blade designs that are aerodynamically optimised for maximum efficiency are known to have a large chord and twist at the inboard sections. Manufacturers have adopted simpler blade designs having a linear chord distribution at the inboard regions. While this has a small effect on the efficiency loss of wind turbines with fixed foundations, the effect of such blade linearization on the aerodynamic performance of floating wind turbines has not been sufficiently dealt with in open literature. This study applies a free-wake vortex model to compare the power and thrust characteristics of floating wind turbines having linearized blades with those having optimised blades. Three- and two-bladed rotors are assumed for different platform surge motions that are representative of different metocean conditions. The study showed that the loss in efficiency through blade linearization is small and similar in magnitude to that encountered in fixed rotors.
Wind resource assessment uncertainty for a TLP-based met mast
Authors: Foussekis D. , Mouzakis F.
Published: September 2021

The current work presents wind resource assessment results of a complete one-year offshore measurement campaign in the Aegean Sea, at 65 m deep waters, with a floating tension leg platform (TLP) equipped with a met mast reaching the height of 44 m above mean sea level (AMSL). Wind conditions uncertainty is evaluated according to the existing standards and guidelines and the additional uncertainty, due to the platform motion, is addressed with two different methods: First by performing wind tunnel experiments, in which the wind sensors are submitted to various controlled motions and second by comparing results of the onboard lidar to a nearby onshore one. Both methods converge that the motion effects are minimal and the additional uncertainty of the mean values due to the TLP motion is ≤1%.
Limiting Wave Conditions for the Safe Maintenance of Floating Wind Turbines
Authors: Jenkins Brian , Prothero Arran , Collu Maurizio , Carroll James , McMillan David , McDonald Alasdair
Published: September 2021

This paper investigates the limiting wave conditions at which a wind turbine technician can complete maintenance activities safely and effectively on a 15MW floating offshore wind turbine. Through linear, frequency-domain statistical analysis of floating turbine motion and applying acceptable motion limits for technician working, significant wave height and peak wave period limits are investigated. It was found that over the range of wave conditions considered, the turbine nacelle motion did not exceed the motion limits for technician working considered in this analysis. Further analysis found that the turbine nacelle motion increased with increasing significant wave height and was also significantly influenced by peak wave period. The impact of differing wave characteristics is also investigated through the use of different wave energy spectra and also found to have an impact on turbine nacelle motion.
Conceptual monopile and tower sizing for the IEA Wind Task 37 Borssele reference wind farm
Authors: McWilliam Michael K. , Natarajan Anand , Pollini Nicolo , Dykes Katherine , Barter Garrett E.
Published: September 2021

This paper explores the preliminary design of the support structures for the IEA Wind Task 37 reference wind farm at the Borssele site III and IV. The study looks at two different design methods that might be used within larger wind farm system design optimization (i.e. lay-out, electrical systems, etc.). The first consists of a scaling tool that scales a detailed design according to the rated power, water depth, hub height and rotor diameter. The second is a physics-based optimization approach that relies on the WISDEM® design tool. This research compares the results of these two methods for the design of both the tower and monopile of the IEA 10-MW and 15-MW reference wind turbines at a range of sea depths (25 m, 30 m, 35 m, 40 m). The two tools yield very similar results in terms of monopile base diameter, support structure natural frequency and mass. WISDEM is then used to also investigate the sensitivity of the design to the tower top forces, wave conditions and the soil conditions. It is shown that tower top forces dominate the design. In general, large diameter structures can carry additional costs associated with manufacturing and transportation requirements. Thus, the paper is concluded with a trade-off study between mass and diameter that quantifies the effect of the reduction in monopile diameter with the increase in structural mass.
A hierarchical supervisory wind power plant controller
Authors: Merz Karl , Chabaud Valentin , Garcia-Rosa Paula B. , Kolle Konstanze
Published: September 2021

The operation of future wind power plants (WPPs) will rely on maximizing overall profit rather than power production. Factors like current electricity price, grid code compliance, and maintenance costs will affect operational decision. Therefore, it is expected that plant control strategies will trade different control objectives while respecting the industrial practice, where the different levels in the hierarchy may be provided by different equipment vendors. This work proposes a plant controller that aims to track an operator power command at the WPP level and to reject low-frequency loading due to turbulent winds at individual turbines. The plant control respects the hierarchy in which the turbine-level controller takes precedence, interacting only via power set-point commands to each turbine. The control algorithm is based on parallel control loops along with look-up tables and gain scheduling, and its simplicity and effectiveness make it well-suited for industrial applications. Preliminary simulation results with a 32-turbine WPP indicate that there is a significant synergy effect by coordinating operation of the turbines in a plant. Structural loads can be reduced on certain turbines without excessively burdening the others, while an accurate plant-wide power tracking is still provided.
Analysis of offshore wind spectra and coherence under neutral stability condition using the two LES models PALM and SOWFA
Authors: Ning X , Krutova M , Bakhoday-Paskyabi M
Published: September 2021

The Parallelized Large-Eddy Model (PALM) and the Simulator for Wind Farm Applications (SOWFA) have been used to simulate the marine boundary layer flows under neutral stability condition. The present work aims to investigate the capability of the two models in reproducing the structure of turbulence in the offshore environment through comparative analysis with a focus on wind spectra and coherence. Wind spectra obtained from the two LES solvers agree well with the empirical spectral model near the surface but show lower turbulence intensity in the low frequency range above the surface layer. Both models also produce highly consistent estimates of coherence with different horizontal and vertical separations, which match well with Davenport and IEC coherence models at height of 180m and 140m respectively. As the height decreases, LES predicts lower vertical coherence compared with the IEC model and the fitted decay coefficient for Davenport model grows as the separation distance increases.