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Simple operated multipurpose temperature control cryostat

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第5期8卷 793-796页

作者： ABBAS T.A. omar M.S. Department of Physics College of Science University of SalahaddinArbilIraqi KurdistanIraq

A suitable simple optical cryostat for optical, magneto-optical, electrical and thermo-electrical measurements was designed. It is suitable for use in a magnetic pool gap as narrow as less than 1 cm. Throughout a long period of time, the heat diffusion process of the cryostat can be easily operated at slow increase in sample temperature in a range 1.25 K/min at 200 K that will be reduced gradually to 0.66 K at room temperature. Liquid nitrogen was used to cool down the temperature. During the operation, the change in the measured energy gap of a semiconductor sample and other physical parameters resulting from the change of temperature can be corrected through the temperature coefficient of that parameter at the corresponding temperature. The cryostat was successfully used for all experiments mentioned above to measure the properties of a single crystal of GaP (Gallium Phosphate) semiconductor.

关键词： Optical cryostat Electrical cryostat Magneto-optical cryostat

Nickel-titanium shape memory alloys made by selective laser melting:a review on process optimisation

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Advances in Manufacturing 2022年第1期10卷 24-58页

作者： omar Ahmed Mohamed Syed Hasan Masood Wei Xu School of Engineering Deakin UniversityGeelongVIC 3216Australia Department of Mechanical Engineering The Higher Institute of Engineering TechnologyBani WaledLibya Department of Mechanical and Product Design Engineering Swinburne University of TechnologyHawthornVIC 3122Australia

Selective laser melting(SLM)is a mainstream powder-bed fusion additive manufacturing(AM)process that creates a three-dimensional(3D)object using a high power laser to fuse fine particles of various metallic powders such as copper,tool steel,cobalt chrome,titanium,tungsten,aluminium and stainless *** the past decade,SLM has received significant attention due to its capability in producing dense parts with superior mechanical *** a premier shape memory alloy,the nickel-titanium(NiTi)shape memory alloy is attractive for a variety of biomedical applications due to its superior mechanical properties,superelasticity,corrosion resistance and *** paper presents a comprehensive review of the recent progress in NiTi alloys produced by the SLM process,with a particular focus on the relationship between processing parameters,resultant microstructures and *** research gaps,challenges and suggestions for future research are also addressed.

关键词： Additive manufacturing(AM) Selective laser melting(SLM) Microstructure NiTi alloy Mechanical properties

Production of renewable fuels by blending bio-oil with alcohols and upgrading under supercritical conditions

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Frontiers of Chemical Science and Engineering 2019年第4期13卷 702-717页

作者： Sainab omar Suzanne Alsamaq Yang Yang Jiawei Wang Chemical Engineering and Applied Chemistry Aston UniversityBirmingham.B47ETUK European Biocncrgy Research Institute Aston UniversityBirminghamB47ETUK

The work studied a non-catalytic upgrading of fast pyrolysis bio-oil by blending under supercritical conditions using methanol,ethanol and isopropanol as solvent and hydrogen *** of the bio-oil and the upgraded bio-oils was carried out including moisture content,elemental content,pH,heating value,gas chromatography-mass spectrometry(GCMS),Fourier transform infrared radiation,13C nuclear magnetic resonance spectroscopy,and thermogravimetric analysis to evaluate the effects of blending and supercritical *** GCMS analysis indicated that the supercritical methanol reaction removed the acids in the bio-oil consequently the pH increased from 2.39 in the crude bio-oil to 4.04 after the supercritical methanol *** ester contents increased by 87.49% after the supercritical methanol reaction indicating ester formation could be the major deacidification mechanism for reducing the acidity of the bio-oil and improving its pH *** blending crude bio-oil with isopropanol was effective in increasing the C and H content,reducing the O content and increasing the heating value to 27.55 from 17.51 MJ·kg^-1 in the crude *** the supercritical isopropanol reaction,the heating value o f the liquid product slightly further increased to 28.85 MJ·kg^-1.

关键词： bio-oil blending supercritical upgrading characterisation

Performance of Desiccant-Based Cooling Systems in Hot-Humid Climates: A Review

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Energy Engineering 2021年第4期118卷 875-909页

作者： Maatouk Khoukhi omar Al Khatib Architectural Engineering Department College of EngineeringUnited Arab Emirates UniversityAl AinUnited Arab Emirates

This paper reviews the principle and application of the thermally activated desiccant cooling systems with their capability to perform efficiently in hot-humid *** paper first introduces the continuous increase of thermal comfort required in building and their relation with the consumption of conventional energy *** importance of desiccant cooling technology and its applications has been introduced as *** energy and environmental issues with the conventional energy supply and the demand with the environmental problems and conditions mainly related to indoor air quality have been also discussed in the second chapter of this *** third part of this paper deals with different techniques and systems applied for cooling and dehumidification including the principles of solid and liquid desiccant ***,these systems perform well in hothumid *** result of a case study of the solid desiccant cooling system combined with solar energy for the desiccant wheel regeneration has been presented in the last chapter in this paper to show the capability of these systems once well applied in a hot-humid climate.

关键词： Desiccant cooling energy performance thermal comfort environmental condition solar energy

Modeling, analysis, and optimization of dimensional accuracy of FDM-fabricated parts using definitive screening design and deep learning feedforward artificial neural network

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Advances in Manufacturing 2021年第1期9卷 115-129页

作者： omar Ahmed Mohamed Syed Hasan Masood Jahar Lal Bhowmik School of Engineering Deakin UniversityGeelongAustralia Department of Mechanical Engineering Higher Institute of Engineering TechnologyBani WalidLibya Department of Mechanical and Product Design Engineering Swinburne University of TechnologyHawthornVIC 3122Australia Department of Health Science and Biostatistics Swinburne University of TechnologyHawthornVIC 3122Australia

Additive manufacturing(AM)technologies such as fused deposition modeling(FDM)rely on the quality of manufactured products and the process ***,the dimensional accuracy and stability of any AM process is essential for ensuring that customer specifications are satisfied at the highest standard,and variations are controlled without significantly affecting the functioning of processes,machines,and product *** study aims to investigate the effects of FDM fabrication conditions on the dimensional accuracy of cylindrical *** this study,a new class of experimental design techniques for integrated second-order definitive screening design(DSD)and an artificial neural network(ANN)are proposed for designing experiments to evaluate and predict the effects of six important operating *** determining the optimum fabrication conditions to obtain better dimensional accuracies for cylindrical parts,the time consumption and number of complex experiments are reduced considerably in this *** optimum fabrication conditions generated through a second-order DSD are verified with experimental *** results indicate that the slice thickness,part print direction,and number of perimeters significantly affect the percentage of length difference,whereas the percentage of diameter difference is significantly affected by the raster-to-raster air gap,bead width,number of perimeters,and part print ***,the results demonstrate that a second-order DSD integrated with an ANN is a more attractive and promising methodology for AM applications.

关键词： Artificial neural network(ANN) OptimizationDefinitive screening design(DSD) Analysis of variance(ANOVA) Fused deposition modeling(FDM) Dimensional accuracy

A novel controllable crowbar based on fault type protection technique for DFIG wind energy conversion system using adaptive neuro-fuzzy inference system

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Protection and Control of Modern Power Systems 2018年第1期3卷 337-348页

作者： omar Noureldeen I.Hamdan Department of Electrical Engineering Faculty of EngineeringSouth Valley UniversityQena 83523Egypt

This paper proposes a novel controllable crowbar based on fault type(CBFT)protection technique for doubly fed induction generator(DFIG)wind energy conversion system connected to *** studied system consists of six DFIG wind turbines with a capacity of 1.5 MW for each of *** operation mechanism of proposed technique is used to connect a set of crowbar resistors in different connection ways via activation of controllable circuit breakers(CBs)depending on the detected fault *** each phase of DFIG,a crowbar resistor is connected in parallel with a controllable CB and all of them are connected in series to grid *** adaptive neuro-fuzzy inference system(ANFIS)networks are designed to detect the fault occurrence,classify the fault type,activate the CBs for crowbar resistors associated with faulted phases during fault period,and deactivate them after fault *** effectiveness of proposed CBFT protection technique is investigated for different fault types such as symmetrical and unsymmetrical faults taking into account the single-phase to ground fault is the most frequently fault type that occurs in power ***,a comparison between the behaviours of studied system in cases of using traditional parallel rotor crowbar,classical outer crowbar,and proposed CBFT protection techniques is *** fluctuations of DC-link voltage,active power,and reactive power for studied system equipped with different protection techniques are ***,the impacts of different crowbar resistance values on the accuracy of proposed technique are *** simulation results show that,the proposed technique enhances the stability of studied wind turbine generators and contributes in protection of their components during faults.

关键词： ANFIS networks Crowbar Power electronic converters DFIG wind turbines Fault types

Design of robust intelligent protection technique for large-scale grid-connected wind farm

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Protection and Control of Modern Power Systems 2018年第1期3卷 179-191页

作者： omar Noureldeen I.Hamdan Electrical Engineering Department Faculty of EngineeringSouth Valley UniversityQena 83523Egypt

This paper presents a design of robust intelligent protection technique using adaptive neuro-fuzzy inference system(ANFIS)approach to detect and classify the fault types during various faults occurrence in large-scale grid-connected wind ***,it is designed to determine the fault location and isolate the wind turbine generators located in the faulted zone during fault occurrence and reconnect them after fault *** studied wind farm has a total rating capacity of 120 MW,where it consists of 60 doubly fed induction generator(DFIG)wind turbines each has a capacity of 2 ***,the wind farm generators are positioned in 6 rows,where each row consists of 10 *** impacts of fault type,fault location,fault duration,cascaded faults,permanent fault and external grid fault on the behaviours of the generated active and reactive power are ***,the impacts of internal and external faults in cases of different transition resistances are *** simulation results indicate that,the proposed ANFIS protection technique has the ability to detect,classify and determine the fault location,then isolate the faulted zones during fault occurrence and reconnect them after fault ***,the wind turbines generators which are located in un-faulted zones can stay to deliver their generated active power to the grid during fault period.

关键词： ANFIS Fault location DFIG Wind farm Active power Reactive power

Effect of malathion on the male reproductive organs of earthworms, Eisenia foetida

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Asian Journal of Andrology 2005年第1期7卷 97-101,页

作者： omar Espinoza-Navarro Eduardo Bustos-Obregon Department of Biology and Health Faculty of Sciences University of Tarapacd Arica Chile Laboratory of Biology of Reproduction ICBM Faculty of Medicine University of Chile Santiago Chile

Aim: To observe the cytotoxic effect of the organophosphate insecticide malathion in the reproductive tissues of the earthworms, Eisenia foetida. Methods: Worms were nourished in soil treated with malathion at single sub-lethal doses of 0, 80, 150, 300 and 600 mg-kg^(-1) soil. (LD_(50) = 880 mg kg^(-1) soil) and evaluated on days 1, 5, 15 and 30 after exposure. The body weights were recorded and male reproductive organs evaluated. Results: Malathion-treated animals showed a significant reduction in body weight in a dose-dependent manner. Malathion treatment modified the disposition of spermatozoa in the basal epithelium of the spermatheca. The Br-deoxyuridine test showed a significant rise in cells in phase S on days 5 and 15. Also, a higher percentage of spermatogonia with fragmented DNA were observed by means of the TdT-mediated dUTP nick-end labeling (TUNEL) technique in the spermatheca of treated animals. Conclusion: Treatment with malathion decreased the body weight and the spermatic viability in spermatheca, altering the cell proliferation and modifying the DNA structure of spermatogonia.

关键词： Eiseniafoetida malathion reproductive organs apoptosis

Robust Stabilization of Load Frequency Control System Under Networked Environment

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International Journal of Automation and computing 2017年第1期14卷 93-105页

作者： Ashraf Khalil Ji-Hong Wang omar Mohamed Electrical and Electronics Engineering Department University of Benghazi Benghazi Libya School of Engineering University of Warwick Coventry UK King Abdullah Ⅱ Faculty of Engineering Princess Sumaya University of Technology Amman Jordan

The deregulation of the electricity market made the open communication infrastructure an exigent need for future power system. In this scenario dedicated communication links are replaced by shared networks. These shared networks are characterized by random time delay and data loss. The random time delay and data loss may lead to system instability if they are not considered during the controller design stage. Load frequency control systems used to rely on dedicated communication links. To meet future power system challenges these dedicated networks are replaced by open communication links which makes the system stochastic. In this paper, the stochastic stabilization of load frequency control system under networked environment is investigated. The shared network is represented by three states which are governed by Markov chains. A controller synthesis method based on the stochastic stability criteria is presented in the paper. A one-area load frequency control system is chosen as case study. The effectiveness of the proposed method for the controller synthesis is tested through simulation. The derived proportion integration （PI） controller proves to be optimum where it is a compromise between compensating the random time delay effects and degrading the system dynamic performance. The range of the PI controller gains that guarantee the stochastic stability is determined. Also the range of the PI controller gains that achieve the robust stochastic stability is determined where the decay rate is used to measure the robustness of the system.

关键词： Load frequency control load frequency control (LFC) Markov chains networked control system robust stabilization.