375 results
Search Results
2. Characteristic of flotation deinking using bio and synthetic surfactant at different air flow rate
- Author
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Nurkholis Hamidi, Trismawati, Mega Nur Sasongko, and Ing Wardana
- Subjects
Chromatography ,Chemistry ,Pulp (paper) ,Airflow ,engineering.material ,Deinking ,Pulp and paper industry ,law.invention ,Pulmonary surfactant ,law ,Performance comparison ,Air flow rate ,engineering ,Synthetic surfactant ,Body orifice - Abstract
Flotation deinking has industrially applied but several problems keep unsolved because limitations have to compete with several variables present. Flotation deinking is multi variables process, so studying flotation deinking is still interesting. In this research, the amount of variables was reduced and focused to the performance comparison between flotation deinking of old newspaper (ONP) using biodegradable fatty acid of morinda citrifolia as the raw bio surfactant (RBS) and biodegradable fatty acid of palm oil that had been converted to be commercial surfactant (CS). The flotation was done at laboratory flotation cell equipped with orifice at different diameter (orifice number 20, 40 and 60) with adjustable airflow rate. Brightness and Effective Residual Ink Concentration (ERIC) of the deinked pulp were measured. The best results were achieved on orifice number 40 with the highest brightness of 41.96 °ISO and 40.96 °ISO when using CS and RBS respectively, and lowest ERIC of 896.82 ppm and 1001.72 ppm when using CS and RBS respectively. The percentage delta of deinking power characteristic between CS and RBS was 2.36% and 11.70% for brightness and ERIC, respectively.
- Published
- 2016
3. Synthesis of reduced graphene oxide (rGO) via chemical reduction
- Author
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V. S. Rangra, Sunil Kumar, and A. K. Thakur
- Subjects
Materials science ,Graphene ,Oxide ,Analytical chemistry ,Infrared spectroscopy ,Graphite oxide ,law.invention ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,Chemical engineering ,law ,symbols ,Graphite ,Fourier transform infrared spectroscopy ,Raman spectroscopy ,Graphene oxide paper - Abstract
Natural flake Graphite was used as the starting material for the graphene synthesis. In the first step flake graphite was treated with oxidizing agents under vigorous conditions to obtain graphite oxide. Layered graphite oxide decorated with oxygen has large inter-layer distance leading easy exfoliation into single sheets by ultrasonication giving graphene oxide. In the last step exfoliated graphene oxide sheets were reduced slowly with the help of reducing agent to obtain fine powder which is labeled as reduced graphene oxide (rGO). This rGO was further characterized by X-Ray Diffraction (XRD), Scanning Tunneling Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy techniques. XRD pattern shows peaks corresponding to (002) graphitic lattice planes indicating the formation of network of sp2 like carbon structure. SEM images show the ultrathin, wrinkled, paper-like morphology of graphene sheets. IR study shows that the graphite has been oxidized to graphite oxide with the presence of various absorption bands confirming the presence of oxidizing groups. The FTIR spectrum of rGO shows no sharp peaks confirming the efficient reduction of rGO. The Raman spectrum shows disorder in the graphene sheets.
- Published
- 2015
4. Surfactant assisted liquid phase exfoliation of graphene via probe tip sonication
- Author
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Gaurav Verma, Arti Sharma, Amrit Pal Toor, and Anjali Joshi
- Subjects
Materials science ,Yield (engineering) ,Graphene ,Sonication ,Liquid phase ,chemistry.chemical_element ,Nanotechnology ,Exfoliation joint ,law.invention ,chemistry ,Pulmonary surfactant ,law ,Carbon ,Graphene oxide paper - Abstract
Graphene is a 2D form of carbon. Due to its wonderful physical and chemical properties has attracted wide interest in recent years. Graphene majorly made by two completely different approches i.e. top-down and bottom up. The top-down approach depends on exfoliation of carbon to provide graphene. Liquid phase exfoliation is more classified in to primarily two categories one is surfactant free and another is surfactant aided Liquid part exfoliation. In this paper we have reportable the liquid phase exfoliation of surfactant aided graphene via probe tip sonication followed by centrifugation. The yield of graphene obtained has been exaggerated and it is easy technique to provide films and graphene composites for photovoltaic applications.
- Published
- 2015
5. Purification and preparation of graphite oxide from natural graphite
- Author
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Camellia Panatarani, Anton Rianto, I Made Joni, and N. Muthahhari
- Subjects
Materials science ,Graphene ,Intercalation (chemistry) ,Infrared spectroscopy ,chemistry.chemical_element ,Graphite oxide ,law.invention ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Elemental analysis ,law ,Organic chemistry ,Graphite ,Carbon ,Graphene oxide paper - Abstract
Graphite oxide has attracted much interest as a possible route for preparation of natural graphite in the large-scale production and manipulation of graphene as a material with extraordinary electronic properties. Graphite oxide was prepared by modified Hummers method from purified natural graphite sample from West Kalimantan. We demonstrated that natural graphite is well-purified by acid leaching method. The purified graphite was proceed for intercalating process by modifying Hummers method. The modification is on the reaction time and temperature of the intercalation process. The materials used in the intercalating process are H2SO4 and KMNO4. The purified natural graphite is analyzed by carbon content based on Loss on Ignition test. The thermo gravimetricanalysis and the Fouriertransform infrared spectroscopy are performed to investigate the oxidation results of the obtained GO which is indicated by the existence of functional groups. In addition, the X-ray diffraction and energy dispersive X-ray spectroscopy are also applied to characterize respectively for the crystal structure and elemental analysis. The results confirmed that natural graphite samples with 68% carbon content was purified into 97.68 % carbon content. While the intercalation process formed a formation of functional groups in the obtained GO. The results show that the temperature and reaction times have improved the efficiency of the oxidation process. It is concluded that these method could be considered as an important route for large-scale production of graphene.
- Published
- 2016
6. Characterization of LiFePO4 cathode by addition of graphene for lithium ion batteries
- Author
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Evvy Kartini and Wagiyo Honggowiranto
- Subjects
Battery (electricity) ,Materials science ,Graphene ,Analytical chemistry ,chemistry.chemical_element ,Lithium-ion battery ,Cathode ,Anode ,law.invention ,chemistry ,law ,Lithium ,Graphite ,Graphene oxide paper - Abstract
The improvement of LiFePO4 (LFP) cathode performance has been performed by addition of Graphene (LFP+Graphene). The cathode was prepared from the active material with 5 wt % graphene and 10 wt % polyvinylidene fluoride in an n-methyl pyrrolidone solvent. Another cathode material used only 5% artificial graphite for comparison (LFP+Graphite). The crystal structure, microstructure, electronic conductivity, electrochemical impedance spectroscopy (EIS) of the cathodes were characterized by X-ray diffraction, SEM, and Impedance spectroscopy, respectively. Two half cell coin batteries were assembled using a lithium metal as an anode and LiPf6 as an electrolyte, and two cathodes (LFP+Graphene) and (LFP+Graphite). Charge discharge performance of battery was characterized by Battery analyser (BTS 8). The electronic conductivity of cathode with grapheme increased of about one order magnitude compared with the only cathode with graphite, namely from 1.97E-7S/cm (LFP+Graphite) to 1.92E-6S/cm (LFP+Graphene). The charge-discharge capacity after 10th cycles of LiFePO4 with graphene decreased of about 0.68% from 114.3 mAh/g to113.1 mAh/g, while LFP with graphite decreased of about 2.84% from 110.2 mAh/g to 107.1 mAh, at 0.1C-rates. It could be concluded that the addition of graphene has increased the ionic conductivity, and improved performance of the LFP lithium ion battery, such as higher capacity and better efficiency.
- Published
- 2016
7. Tuning the electronic band gap of graphene by oxidation
- Author
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Shweta D. Dabhi and Prafulla K. Jha
- Subjects
Materials science ,Condensed matter physics ,Graphene ,business.industry ,Band gap ,Oxide ,Physics::Optics ,Electronic structure ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Optoelectronics ,Physics::Chemical Physics ,Electronic band structure ,Bilayer graphene ,business ,Graphene nanoribbons ,Graphene oxide paper - Abstract
Using plane wave pseudo potential density functional theory, we studied the electronic properties of graphene with different C:O ratio. In this work, we discussed the changes that occur in electronic band structure of graphene functionalized with different amount of epoxy group. Electronic band gap depends on C:O ratio in graphene oxide containing epoxy group. The present work will have its implication for making devices with tunable electronic properties by oxidizing graphene.
- Published
- 2015
8. Technique of ethanol food grade production with batch distillation and dehydration using starch-based adsorbent
- Author
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Umi Rofiqah, Hikmatun Ni’mah, Namira Tedji, Tri Widjaja, and Ali Altway
- Subjects
Fractional distillation ,Fusel alcohol ,Waste management ,biology ,Batch distillation ,Chemistry ,food and beverages ,Isopropyl alcohol ,biology.organism_classification ,Pulp and paper industry ,Zymomonas mobilis ,law.invention ,chemistry.chemical_compound ,law ,Fermentation ,Pichia stipitis ,Distillation - Abstract
Development and innovation of ethanol food grade production are becoming the reasearch priority to increase economy growth. Moreover, the government of Indonesia has established regulation for increasing the renewable energy as primary energy. Sorghum is cerealia plant that contains 11-16% sugar that is optimum for fermentation process, it is potential to be cultivated, especially at barren area in Indonesia. The purpose of this experiment is to learn about the effect of microorganisms in fermentation process. Fermentation process was carried out batchwise in bioreactor and used 150g/L initial sugar concentration. Microorganisms used in this experiment are Zymomonas mobilis mutation (A3), Saccharomyces cerevisiae and mixed of Pichia stipitis. The yield of ethanol can be obtained from this experiment. For ethanol purification result, distillation process from fermentation process has been done to search the best operation condition for efficiency energy consumption. The experiment for purification was divided into two parts, which are distillation with structured packing steel wool and adsorption (dehydration) sequencely. In distillation part, parameters evaluation (HETP and pressure drop) of distillation column that can be used for scale up are needed. The experiment was operated at pressure of 1 atm. The distillation stage was carried out at 85 °C and reflux ratio of 0.92 with variety porosities of 20%, 40%, and 60%. Then the adsorption process was done at 120°C and two types of adsorbent, which are starch – based adsorbent with ingredient of cassava and molecular sieve 3A, were used. The adsorption process was then continued to purify the ethanol from impurities by using activated carbon. This research shows that the batch fermentation process with Zymomonas mobilis A3 obtain higher % yield of ethanol of 40,92%. In addition to that, for purification process, the best operation condition is by using 40% of porosity of stuctured packing steel wool in distillation stage and starch-based adsorbent in adsorption stage, which can obtain ethanol content of 92,15% with acetic acid percentage of 0,001% and the rest is water. This result is qualified for ethanol food grade specification which is between 90 - 94 % of ethanol with maximum percentage of acetic acid is 0,003%, and passes in fusel oil and isopropyl alcohol test.
- Published
- 2015
9. Growth of bi- and tri-layered graphene on silicon carbide substrate via molecular dynamics simulation
- Author
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Tiem Leong Yoon, Tjun Kit Min, and Thong Leng Lim
- Subjects
Materials science ,Graphene ,Nanotechnology ,Crystal growth ,Epitaxy ,law.invention ,Bond length ,chemistry.chemical_compound ,Molecular dynamics ,chemistry ,law ,Chemical physics ,Silicon carbide ,Graphene nanoribbons ,Graphene oxide paper - Abstract
Molecular dynamics (MD) simulation with simulated annealing method is used to study the growth process of bi- and tri-layered graphene on a 6H-SiC (0001) substrate via molecular dynamics simulation. Tersoff-Albe-Erhart (TEA) potential is used to describe the inter-atomic interactions among the atoms in the system. The formation temperature, averaged carbon-carbon bond length, pair correlation function, binding energy and the distance between the graphene formed and the SiC substrate are quantified. The growth mechanism, graphitization of graphene on the SiC substrate and characteristics of the surface morphology of the graphene sheet obtained in our MD simulation compare well to that observed in epitaxially grown graphene experiments and other simulation works.
- Published
- 2015
10. Electrostatic super coupling in copper sulphide (Cu2S)-reduced graphene oxide composite and their enhanced optical characteristics
- Author
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M. Kamalanathan and R. Gopalakrishnan
- Subjects
Materials science ,Band gap ,Graphene ,Composite number ,Oxide ,chemistry.chemical_element ,Copper ,law.invention ,symbols.namesake ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,law ,symbols ,Crystallite ,Composite material ,Raman spectroscopy ,Graphene oxide paper - Abstract
The composite of reduced graphene oxide-Cu2S was synthesized by facile and cost effective one-step hydrothermal process. Powder XRD reveals the formation of Reduced Graphene Oxide (RGO) and Cu2S composite nanostructures. Average crystallite size of 16.5 nm was estimated for composite material from XRD measurement. Raman and FTIR analysis confirm the formation of graphene oxide and reduced graphene oxide-Cu2S composites. Origin of strong electrostatic interaction between Cu2S and RGO was also inferred from FTIR and Raman investigations. UV absorption spectral analysis illustrates the wide optical absorption region of the prepared composite material. The band gap of the composite was also calculated using the absorbance spectra. The obtained band gap of the composite was 1.64 eV which was much lower expected for copper sulphide particles in nano regime.
- Published
- 2015
11. Investigation of chemically synthesized graphene as counter electrode for dye sensitized solar cells
- Author
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Mahesh S. Roy, Rakesh Sharma, Shejale Kiran Prakash, and Mahesh Kumar
- Subjects
Auxiliary electrode ,Materials science ,Graphene ,Oxide ,Nanoparticle ,Nanotechnology ,Tin oxide ,law.invention ,chemistry.chemical_compound ,Dye-sensitized solar cell ,chemistry ,law ,Screen printing ,Graphene oxide paper - Abstract
Graphene was synthesized and used as a counter electrode in place of platinum in dye sensitized solar cells. This study reveals that the graphene synthesized by reduction of graphene oxide still contains functional groups even after reduction. The synthesized graphene counter electrodes were prepared by screen printing fabrication techniques. The influence of temperature variation on the films morphology, crystallinity, and its interfacial adhesiveness to the fluorine doped tin oxide coated glass were studied. Screen printing technique has shown uniform surface, decreased agglomeration of nanoparticles and high film adhesiveness. The screen printed film annealed at 400°C reveals best surface morphology.
- Published
- 2014
12. Preparation and characterization of solar exfoliated graphene
- Author
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Sreejesh M, Udaya Bhat K, and Nagaraja H. S
- Subjects
Materials science ,Graphene ,Graphite oxide ,Nanotechnology ,Exfoliation joint ,law.invention ,Characterization (materials science) ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,law ,symbols ,Graphite ,Fourier transform infrared spectroscopy ,Raman spectroscopy ,Graphene oxide paper - Abstract
Hummer's method was used for the chemical synthesis of graphite oxide from graphite flakes. Simultaneous exfoliation and reduction of graphite oxide to Graphene was achieved through focused solar light irradiation using a convex lens. The morphological characteristics were studied using SEM and TEM. Layered morphology of Graphene was observed through TEM. Raman spectra and FTIR were used for the structural characterization of Graphene. EDAX analysis showed the drop in oxygen content during exfoliation. The method offered a faster, easier and environmental friendly method to produce Graphene for potential applications.
- Published
- 2014
13. Synthesis and characterizations of graphene oxide and reduced graphene oxide nanosheets
- Author
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M. Venkanna and Amit K. Chakraborty
- Subjects
Materials science ,Graphene ,Graphene foam ,Oxide ,Nanotechnology ,Graphite oxide ,law.invention ,symbols.namesake ,chemistry.chemical_compound ,chemistry ,law ,symbols ,Graphite ,Raman spectroscopy ,Graphene nanoribbons ,Graphene oxide paper - Abstract
Interest in graphene on its excellent mechanical, electrical, thermal and optical properties, it’s very high specific surface area, and our ability to influence these properties through chemical functionalization. Chemical reduction of graphene oxide is one of the main routes of preparation for large quantities of graphenes. Hydrazine hydrate used as reducing agent to prepare for the reduced graphene oxide (RGO). There are a number of methods for generating graphene and chemically modified graphene from natural graphite flakes, graphite derivative (such as graphite oxide) and graphite interaction compounds (i.e. expandable graphite). Here we review the use of colloidal suspensions of reduced graphene oxide (RGO) with large scalable, and is adaptable to a wide variety of applications. The graphene oxide (GO) and the reduced material (RGO) were characterized by XRD, UV-Vis spectroscopy, Thermo-gravimetric analysis (TGA), Raman spectroscopy and Field emission Scanning electron microscopy (FESEM) etc.
- Published
- 2014
14. Structure of graphene oxide dispersed with ZnO nanoparticles
- Author
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Devendra K. Pandey, Rishikesh Yadav, and Purnima Swarup Khare
- Subjects
Materials science ,Graphene ,Oxide ,Nanotechnology ,law.invention ,Nanomaterials ,chemistry.chemical_compound ,Zno nanoparticles ,chemistry ,law ,Emission spectrum ,Dispersion (chemistry) ,Spectroscopy ,Graphene oxide paper - Abstract
Graphene has been proposed as a promising two-dimensional nanomaterial with outstanding electronic, optical, thermal and mechanical properties for many applications. In present work a process of dispersion of graphene oxide with ZnO nanoparticles in ethanol solution with different pH values, have been studied. Samples have been characterized by XRD, SEM, PL, UV-visible spectroscopy and particles size measurement. The results analysis indicates overall improved emission spectrum. It has been observed that the average diameter of RGO (Reduced Graphene Oxide) decreases in presence of ZnO nanoparticles from 3.8μm to 0.41μm.
- Published
- 2014
15. Photoluminescence study in diaminobenzene functionalized graphene oxide
- Author
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Shyamal K. Saha and Abhisek Gupta
- Subjects
Photoluminescence ,Materials science ,Passivation ,Graphene ,Composite number ,Oxide ,Nanotechnology ,law.invention ,symbols.namesake ,chemistry.chemical_compound ,chemistry ,law ,symbols ,Surface modification ,Raman spectroscopy ,Graphene oxide paper - Abstract
Being an excellent electronic material graphene is a very poor candidate for optoelectronic applications. One of the major strategies to develop the optical property in GO is the functionalization of graphene oxide (GO). In the present work GO sheets are functionalized by o-phenylenediamine to achieve diaminobenzene functionalized GO composite (DAB-GO). Formation of DAB-GO composite is further characterized by FTIR, UV, Raman studies. Excellent photoluminescence is observed in DAB-GO composite via passivation of the surface reactive sites by ring-opening amination of epoxides of GO.
- Published
- 2014
16. Characterization of few-layered graphene grown by carbon implantation
- Author
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Kin Kiong Lee, Jeffrey C. McCallum, and David N. Jamieson
- Subjects
Electron mobility ,Ion implantation ,Materials science ,Graphene ,law ,Graphene foam ,Nanotechnology ,Field-effect transistor ,Bilayer graphene ,Graphene nanoribbons ,law.invention ,Graphene oxide paper - Abstract
Graphene is considered to be a very promising material for applications in nanotechnology. The properties of graphene are strongly dependent on defects that occur during growth and processing. These defects can be either detrimental or beneficial to device performance depending on defect type, location and device application. Here we present experimental results on formation of few-layered graphene by carbon ion implantation into nickel films and characteristics of graphene devices formed by graphene transfer and lithographic patterning. Micro-Raman spectroscopy was used to determine the number of graphene layers formed and identify defects arising from the device processing. The graphene films were cleaned by annealing in vacuum. Transport properties of cleaned graphene films were investigated by fabrication of back-gated field-effect transistors, which exhibited high hole and electron mobility of 1935 and 1905 cm2/Vs, respectively.
- Published
- 2014
17. Graphene oxide-based nanohybrid for label-free optical sensing
- Author
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Anna Borriello, Pietro La Manna, Pellegrino Musto, Giovanna De Luca, Lucia Sansone, and Michele Giordano
- Subjects
Materials science ,genetic structures ,Graphene ,Oxide ,Single-mode optical fiber ,Sorption ,Nanotechnology ,Fiber optics ,complex mixtures ,eye diseases ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Molecule ,sense organs ,Sensor, fiber optics, graphene oxide ,Refractive index ,Graphene oxide ,Sensor ,Label free ,Graphene oxide paper - Abstract
In this study we report on optical sensor, based on the sorption properties of graphene film reduced on the tip of a standard single mode optical fiber. Reflectance measurements will be carried out to investigate the changes in the graphene refractive index due to sorption when the sensor probe was exposed to gas molecules. © 2014 AIP Publishing LLC.
- Published
- 2014
18. Design, simulation and analysis of 3 kW low speed axial flux permanent magnet generator
- Author
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Muhammad Kasim, Muhammad Fathul Hikmawan, and Pudji Irasari
- Subjects
Engineering ,Rotor (electric) ,Stator ,business.industry ,Electrical engineering ,Mechanical engineering ,Permanent magnet synchronous generator ,Finite element method ,law.invention ,Conductor ,Generator (circuit theory) ,law ,Heat transfer ,business ,Engineering design process - Abstract
Design and simulation of an axial flux permanent magnet generator (AFPMG) have been described in this paper. It was designed using the single rotor – single stator construction. The analytical method was using in the design process. The design process also employed the simulation using Finite Element Method Magnetics (FEMM) 4.2 software for identifying the magnetic characteristic and heat transfer. The effect of fill factor (FF) variation on the generator performances also observed in this paper. The design result shows that using the selected FF, the conductor diameter, power output, efficiency and heat distribution are affected but not for the Bg. The generator output can achieve up to 5.2 kW using the FF 0.4 which is more than assumed power output at the pre-design using FF 0.3. It also can be seen that the increasing FF will increase the power output and the efficiency. Despite a higher temperature compared with FF 0.3 and 0.35, the value of 0.4 is the most appropriate FF for designing the AFPMG.
- Published
- 2016
19. Simple energy barrier for component mixture of natural gases
- Author
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Aleksey Bubenchikov, M. A. Bubenchikov, Olesya V Usenko, Egor A. Tarasov, and Oleg Matvienko
- Subjects
Range (particle radiation) ,Materials science ,нанопоры ,chemistry.chemical_element ,Nanoparticle ,Nanotechnology ,Methane ,law.invention ,chemistry.chemical_compound ,молекулы гелия ,chemistry ,углеродные наночастицы ,law ,Chemical physics ,Molecule ,пористые материалы ,молекулы метана ,Physics::Chemical Physics ,Porous medium ,Porosity ,Helium ,Filtration - Abstract
This paper investigates the ability of a test molecule to overcome the energy barrier being in the gap between spherical nanoparticles. Three particles make a primitive structural element of composite porous material. The ability of molecules to converge with nanoparticles and then to move through more powerful repulsion field defines the filtration properties of porous materials. This paper presents the investigation of carbon nanoparticles and molecules of helium and methane bombarding them. Calculations proved that methane molecules can not get through three particles if the gap equals to 3.5 nm. For helium molecules this value makes 1.02 nm. These gaps remain the same when the size of nanoparticles increases. Therefore filters for helium separated from natural gas are to have nanopores within the range from 1.02 nm to 3.5 nm.
- Published
- 2016
20. Numerical study on distribution law of magnetic field and temperature field around the crack induced by eddy currents
- Author
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Laibin Zhang, Fan Zhou, Wenpei Zheng, and Min He
- Subjects
Nuclear magnetic resonance ,Materials science ,Field (physics) ,Ferromagnetism ,law ,Thermal ,Thermography ,Eddy current ,Distribution law ,Mechanics ,Excitation ,Magnetic field ,law.invention - Abstract
Alternative current field measurement (ACFM) and eddy current thermography are both induced by eddy currents, and it is a commonality between them. The commonality has laid a good foundation for the combination of the two testing techniques. In this paper, a numerical study on distribution law of magnetic field and temperature field around the crack using eddy current excitation is carried out. The feasibility of the combination of ACFM and eddy current thermography is discussed as well. A specimen made of ferromagnetic material is tested by a U-shaped inducer, and a semielliptical crack is built on the specimen. The distribution law of magnetic field and temperature field is both studied using the same eddy current excitation. The relationship between the crack size and distribution of magnetic field and temperature field is identified by altering the length and depth of the crack. Through comparisons, the magnetic distribution law around the crack in this paper is consistent with that of ACFM, and the maximum temperature difference around the crack meets the inspection requirement of a thermal imager. These findings might make it possible to eventually combine ACFM and eddy current thermography.
- Published
- 2016
21. FlightGear application for flight simulation of a mini-UAV
- Author
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Roman Jasek and Tomáš Vogeltanz
- Subjects
Aircraft flight mechanics ,FlightGear ,Engineering ,business.product_category ,autopilot ,business.industry ,UAV ,PID ,PID controller ,Control engineering ,simulation ,airplane ,Throttle ,Flight simulator ,law.invention ,Airplane ,modelling ,Control theory ,law ,Cascade ,Autopilot ,business ,aircraft ,Simulation - Abstract
This paper presents using of FlightGear application for flight simulation of a mini-UAV (Unmanned Aerial Vehicle). The first part of the paper is about general information of UAVs and about the fundamentals of airplane flight mechanics. The main section summarizes the information about FlightGear application and describes a way of using the application to simulate a mini-UAV. The process of altitude change by using autopilot has been simulated. In the created simulation, three stage cascade controller was used for an altitude control. Heading was controlled by 2 stage cascade PID (Proportional-Integral-Derivative) controller. An automatic throttle system was applied for a velocity control. The setting of all controllers is included in the description of the simulation. Finally, the results of FlightGear simulation are discussed.
- Published
- 2015
22. Economical and eco-friendly recycling of used dry batteries for synthesis of graphene oxide by sheer exfoliation in presence of SDS
- Author
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Mahesh Agharkar, Sachin Kochrekar, Slah Hidouri, Manjunath D. Salgaonkar, Mrunal Gharge, and Musibau A. Azeez
- Subjects
Battery (electricity) ,Materials science ,Graphene ,Oxide ,Nanotechnology ,Exfoliation joint ,Environmentally friendly ,Characterization (materials science) ,law.invention ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,law ,symbols ,Graphite ,Raman spectroscopy - Abstract
Graphene is a two-dimensional form of graphite that has attracted great curiosity for its novel physical properties. A key challenge that has emerged is how to create large amounts of graphene at low cost. The purpose of this Paper is to explore a new method to exfoliate graphite extracted from used dry battery in a small scale blender; in presence of SDS surfactant to synthesize graphene oxide, which can be then reduced to graphene. Quantity of SDS required is extremely less (1/10th) of graphite, and it replaces several steps and chemicals such as KMnO4, H2O2, H2SO4 and NaNO3. In this paper, we present the new process and preliminary characterization of synthesized graphene oxide by Raman and UV-Vis absorbance spectroscopy and ATR-IR spectroscopy.
- Published
- 2015
23. Weight optimization of large span steel truss structures with genetic algorithm
- Author
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Radu Hulea, Cristian Mojolic, and Bianca Roxana Pârv
- Subjects
Engineering ,Chord (geometry) ,Bearing (mechanical) ,business.industry ,Tension (physics) ,Truss ,Structural engineering ,law.invention ,Structural load ,Buckling ,law ,Genetic algorithm ,business ,Roof - Abstract
The paper presents the weight optimization process of the main steel truss that supports the Slatina Sport Hall roof. The structure was loaded with self-weight, dead loads, live loads, snow, wind and temperature, grouped in eleven load cases. The optimization of the structure was made using genetic algorithms implemented in a Matlab code. A total number of four different cases were taken into consideration when trying to determine the lowest weight of the structure, depending on the types of connections with the concrete structure ( types of supports, bearing modes), and the possibility of the lower truss chord nodes to change their vertical position. A number of restrictions for tension, maximum displacement and buckling were enforced on the elements, and the cross sections are chosen by the program from a user data base. The results in each of the four cases were analyzed in terms of weight, element tension, element section and displacement. The paper presents the optimization process and the conclusions drawn.
- Published
- 2015
24. Benchmark of numerical tools simulating beam propagation and secondary particles in ITER NBI
- Author
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P. Veltri, Gianluigi Serianni, E. Dlougach, M. J. Singh, R. Hemsworth, and E. Sartori
- Subjects
Physics ,Nuclear engineering ,Particle accelerator ,Injector ,Electron ,Secondary electrons ,Magnetic field ,law.invention ,Beamline ,law ,Physics::Accelerator Physics ,Atomic physics ,Beam (structure) ,Power density - Abstract
Injection of high energy beams of neutral particles is a method for plasma heating in fusion devices. The ITER injector, and its prototype MITICA (Megavolt ITER Injector and Concept Advancement), are large extrapolations from existing devices. Therefore nu merical modeling is needed to set thermo - mechanical requirements for all beam - facing components. As the power and charge deposition originates from several sources (primary beam, co - accelerated electrons, and secondary production by beam - gas, beam - surface, and electron - surface interaction), the beam propagation along the beam line is simulated by comprehensive 3D models. This paper presents a comparative study between two codes: BTR has been used for several years in the design of the ITER HNB components; the SAMANTHA code was independently developed and includes additional phenomena, like secondary particles generated by collision of beam particles with the background gas. The code comparison is valuable in the perspective of the upcoming experimental oper ations, in order to prepare a reliable numerical support to the interpretation of experimental measurements in the beam test facilities. The power density maps calculated on the Electrostatic Residual Ion Dump (ERID) is chosen as the benchmark, as they dep end on the electric and magnetic fields as well as on the evolution of the beam species via interaction with the gas. Finally the paper shows additional results provided by SAMANTHA, like the power deposition onto the Cryopumps due to secondary electrons accelerated by the ERID fringe - field
- Published
- 2015
25. A novel percussion type droplet-on-demand generator
- Author
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Taaha Hussain, Priyesh A. Patel, Ramanarayanan Balachandran, and Nicos Ladommatos
- Subjects
Chemistry ,business.industry ,Nozzle ,Electrical engineering ,Solenoid ,Mechanics ,Piezoelectricity ,law.invention ,Physics::Fluid Dynamics ,Generator (circuit theory) ,Momentum ,Surface tension ,law ,Physics::Atomic and Molecular Clusters ,Hammer ,business ,Body orifice - Abstract
Numerous engineering applications require generation of droplets on demand which are of high uniformity and constant size. The common method to produce droplets is to drive liquid at high pressure through a small orifice/nozzle. The liquid stream disintegrates into small droplets. However this method normally requires large volumes of liquid and is not suitable for applications where single droplets of constant size is required. Such applications require droplet-on-demand generators which commonly employ piezoelectric or pneumatic actuation. It is well known that piezoelectric generators are hard to employ at high pressure and, high temperature applications, and the pneumatic generators often produce satellite (secondary) droplets. This paper describes the development of a novel percussion type droplet-on-demand generator, which overcomes some of the above difficulties and is capable of producing single droplets on demand. The generator consists of a cylindrical liquid filled chamber with a small orifice at the bottom. The top of the chamber is covered with a thin flexible metal disc. A small metal pin is employed to hammer/impact the top metal surface to generate a pressure pulse inside the liquid chamber. The movement and the momentum of the metal pin are controlled using a solenoid device. The pressure pulse generated overcomes the surface tension of the liquid meniscus at the exit of the orifice and ejects a single droplet. The work presented in this paper will demonstrate the capabilities of the droplet generator.
- Published
- 2015
26. Electricity storage using a thermal storage scheme
- Author
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Alexander J. White
- Subjects
Engineering ,Thermal efficiency ,business.industry ,Renewable heat ,Electrical engineering ,Coefficient of performance ,Thermal energy storage ,Energy storage ,law.invention ,Stand-alone power system ,law ,Waste heat ,business ,Process engineering ,Heat pump - Abstract
The increasing use of renewable energy technologies for electricity generation, many of which have an unpredictably intermittent nature, will inevitably lead to a greater demand for large-scale electricity storage schemes. For example, the expanding fraction of electricity produced by wind turbines will require either backup or storage capacity to cover extended periods of wind lull. This paper describes a recently proposed storage scheme, referred to here as Pumped Thermal Storage (PTS), and which is based on “sensible heat” storage in large thermal reservoirs. During the charging phase, the system effectively operates as a high temperature-ratio heat pump, extracting heat from a cold reservoir and delivering heat to a hot one. In the discharge phase the processes are reversed and it operates as a heat engine. The round-trip efficiency is limited only by process irreversibilities (as opposed to Second Law limitations on the coefficient of performance and the thermal efficiency of the heat pump and heat engine respectively). PTS is currently being developed in both France and England. In both cases, the schemes operate on the Joule-Brayton (gas turbine) cycle, using argon as the working fluid. However, the French scheme proposes the use of turbomachinery for compression and expansion, whereas for that being developed in England reciprocating devices are proposed. The current paper focuses on the impact of the various process irreversibilities on the thermodynamic round-trip efficiency of the scheme. Consideration is given to compression and expansion losses and pressure losses (in pipe-work, valves and thermal reservoirs); heat transfer related irreversibility in the thermal reservoirs is discussed but not included in the analysis. Results are presented demonstrating how the various loss parameters and operating conditions influence the overall performance.
- Published
- 2015
27. Toward practical 3D radiography of pipeline girth welds
- Author
-
Arjan Flikweert, Casper Wassink, Martijn Hol, and Philip van Meer
- Subjects
Engineering ,Engineering drawing ,business.industry ,Image quality ,Pipeline (computing) ,Ultrasonic testing ,Detector ,Mechanical engineering ,ComputerApplications_COMPUTERSINOTHERSYSTEMS ,Welding ,Sizing ,Girth (geometry) ,law.invention ,law ,business ,Digital radiography - Abstract
Digital radiography has made its way into in-the-field girth weld testing. With recent generations of detectors and x-ray tubes it is possible to reach the image quality desired in standards as well as the speed of inspection desired to be competitive with film radiography and automated ultrasonic testing. This paper will show the application of these technologies in the RTD Rayscan system. The method for achieving an image quality that complies with or even exceeds prevailing industrial standards will be presented, as well as the application on pipeline girth welds with CRA layers. A next step in development will be to also achieve a measurement of weld flaw height to allow for performing an Engineering Critical Assessment on the weld. This will allow for similar acceptance limits as currently used with Automated Ultrasonic Testing of pipeline girth welds. Although a sufficient sizing accuracy was already demonstrated and qualified in the TomoCAR system, testing in some applications is restricted to time limits. The paper will present some experiments that were performed to achieve flaw height approximation within these time limits.
- Published
- 2015
28. Methods for nonlinear analysis, simulation and animation of land-survey spacecraft guidance
- Author
-
Tatyana Somova and Sergey Somov
- Subjects
Spacecraft ,business.industry ,Animation ,law.invention ,Azimuth ,Telescope ,Circular motion ,Software ,Geography ,Cardinal point ,Spitzer Space Telescope ,law ,Computer vision ,Artificial intelligence ,business - Abstract
Obtained in the space photos a ground resolution depends on a spacecraft spatial angular motion during optoelectronic survey. The paper studies case of optimal equalization of an image longitudinal velocity in the focal plane of telescope and tackles the problem of defining initial azimuth of the scanning survey under the condition of minimizing quadratic functional of image cross velocity values on edges of the CCD linear array. Results of a simulated survey of random surface object are presented, and the change of initial azimuth value for various survey angles within the swath is examined. The paper presents also a brief description of developed software for designing the space telescope characteristics, simulation and animation of the land-survey spacecraft spatial motion and gives recommendations for its applications.
- Published
- 2014
29. A dynamic system matching technique for improving the accuracy of MEMS gyroscopes
- Author
-
Allen R. Stubberud, Stephen C. Stubberud, and Peter Stubberud
- Subjects
Engineering ,business.industry ,Vibrating structure gyroscope ,Gyroscope ,Filter (signal processing) ,Electronic circuit design ,Signal ,law.invention ,Spread spectrum ,Noise ,Control theory ,law ,Electronic engineering ,business ,Electronic circuit - Abstract
A classical MEMS gyro transforms angular rates into electrical values through Euler's equations of angular rotation. Production models of a MEMS gyroscope will have manufacturing errors in the coefficients of the differential equations. The output signal of a production gyroscope will be corrupted by noise, with a major component of the noise due to the manufacturing errors. As is the case of the components in an analog electronic circuit, one way of controlling the variability of a subsystem is to impose extremely tight control on the manufacturing process so that the coefficient values are within some specified bounds. This can be expensive and may even be impossible as is the case in certain applications of micro-electromechanical (MEMS) sensors. In a recent paper [2], the authors introduced a method for combining the measurements from several nominally equal MEMS gyroscopes using a technique based on a concept from electronic circuit design called dynamic element matching [1]. Because the method in this paper deals with systems rather than elements, it is called a dynamic system matching technique (DSMT). The DSMT generates a single output by randomly switching the outputs of several, nominally identical, MEMS gyros in and out of the switch output. This has the effect of 'spreading the spectrum' of the noise caused by the coefficient errors generated in the manufacture of the individual gyros. A filter can then be used to eliminate that part of the spread spectrum that is outside the pass band of the gyro. A heuristic analysis in that paper argues that the DSMT can be used to control the effects of the random coefficient variations. In a follow-on paper [4], a simulation of a DSMT indicated that the heuristics were consistent. In this paper, analytic expressions of the DSMT noise are developed which confirm that the earlier conclusions are valid. These expressions include the various DSMT design parameters and, therefore, can be used as design tools for DSMT systems.
- Published
- 2014
30. Eddy current pulsed thermography for fatigue evaluation of gear
- Author
-
Brian Shaw, Jishan Zhang, Bin Gao, Aijun Yin, and Gui Yun Tian
- Subjects
Engineering ,business.industry ,Acoustics ,Blind signal separation ,law.invention ,Eddy current pulsed thermography ,law ,Eddy-current testing ,Nondestructive testing ,Range (statistics) ,Eddy current ,Electronic engineering ,Sensitivity (control systems) ,Transient (oscillation) ,business - Abstract
The pulsed eddy current (PEC) technique generates responses over a wide range of frequencies, containing more spectral coverage than traditional eddy current inspection. Eddy current pulsed thermography (ECPT), a newly developed non-destructive testing (NDT) technique, has advantages such as rapid inspection of a large area within a short time, high spatial resolution, high sensitivity and stand-off measurement distance. This paper investigates ECPT for the evaluation of gear fatigue tests. The paper proposes a statistical method based on single channel blind source separation to extract details of gear fatigue. The discussion of transient thermal distribution and patterns of fatigue contact surfaces as well as the non-contact surfaces have been reported. In addition, the measurement for gears with different cycles of fatigue tests by ECPTand the comparison results between ECPT with magnetic Barkhausen noise (MBN) have been evaluated. The comparison shows the competitive capability of ECPT in fatigue evaluation.
- Published
- 2014
31. The influence of Reynolds numbers on resistance properties of jet pumps
- Author
-
Q. Li, Q. Geng, and G. Zhou
- Subjects
Engineering ,Jet (fluid) ,Stirling engine ,business.industry ,Flow (psychology) ,Mechanical engineering ,Reynolds number ,Injector ,Computational fluid dynamics ,law.invention ,Physics::Fluid Dynamics ,symbols.namesake ,law ,symbols ,Thermoacoustic heat engine ,business ,Heat engine - Abstract
Jet pumps are widely used in thermoacoustic Stirling heat engines and pulse tube cryocoolers to eliminate the effect of Gedeon streaming. The resistance properties of jet pumps are principally influenced by their structures and flow regimes which are always characterized by Reynolds numbers. In this paper, the jet pump of which cross section contracts abruptly is selected as our research subject. Based on linear thermoacoustic theory, a CFD model is built and the oscillating flow of the working gas is simulated and analyzed with different Reynolds numbers in the jet pump. According to the calculations, the influence of different structures and Reynolds numbers on the resistance properties of the jet pump are analyzed and presented. The results show that Reynolds numbers have a great influence on the resistance properties of jet pumps and some empirical formulas which are widely used are unsuitable for oscillating flow with small Reynolds numbers. This paper provides a more comprehensive understanding on resistance properties of jet pumps with oscillating flow and is significant for the design of jet pumps in practical thermoacoustic engines and refrigerators.
- Published
- 2014
32. Monitoring of surface burn after grinding larger bearing rings
- Author
-
M. Čilliková, A. Mičietová, and M. Neslušan
- Subjects
Bearing (mechanical) ,Materials science ,Metallurgy ,Grinding wheel ,Grinding ,law.invention ,Coolant ,symbols.namesake ,law ,Non destructive ,symbols ,Calibration ,Thermal damage ,Composite material ,Barkhausen effect - Abstract
This paper deals with detection of surface burn after grinding of larger bearing rings made of case - hardened steels. The paper reports about calibration of Barkhausen noise technique for non destructive monitoring of grinding operations for rings of diameter in the range of 600 up to 4000 mm. Properly suggested monitoring concept enables to detect thermal damage due to grinding wheel wear as well as insufficient coolant supply. Further, grinding burn associated with lack of coolant can be clearly distinguished from damage corresponding grinding wheel wear. The paper also discusses increasing magnetoelastic responses obtained after grinding rings of higher diameters.
- Published
- 2014
33. The matching technique of directed cyclic graph for task assignment problem
- Author
-
Wan Nor Munirah Ariffin and Shaharuddin Salleh
- Subjects
Theoretical computer science ,law ,Line graph ,Voltage graph ,Graph partition ,Graph (abstract data type) ,Directed graph ,Null graph ,Graph property ,Butterfly graph ,MathematicsofComputing_DISCRETEMATHEMATICS ,Mathematics ,law.invention - Abstract
The scheduling and mapping of task graph to processors is considered to be the most crucial NP-complete in parallel and distributed computing systems. In this paper, the theoretical graph application using simple partitioning technique is presented to assign a number of tasks onto two processors. This paper addresses a directed-weighted cyclic graph. The effort is to reduce the graph onto directed acyclic graph. A Kernighan-Lin algorithm is applied to obtain the partition of tasks. Combining the technique of reduction and partitioning lead to an efficient graph-mapping concept.
- Published
- 2014
34. Determination of linear defect depths from eddy currents disturbances
- Author
-
Artur L. Ribeiro, Dario Pasadas, Tiago Rocha, and Helena G. Ramos
- Subjects
Engineering ,business.industry ,Acoustics ,Flux ,Finite element method ,law.invention ,Magnetic field ,law ,Eddy-current testing ,Eddy current ,Electronic engineering ,Current (fluid) ,business ,Penetration depth ,Excitation - Abstract
One of the still open problems in the inspection research concerns the determination of the maximum depth to which a surface defect goes. Eddy current testing being one of the most sensitive well established inspection methods, able to detect and characterize different type of defects in conductive materials, is an adequate technique to solve this problem. This paper reports a study concerning the disturbances in the magnetic field and in the lines of current due to a machined linear defect having different depths in order to extract relevant information that allows the determination of the defect characteristics. The image of the eddy currents (EC) is paramount to understand the physical phenomena involved. The EC images for this study are generated using a commercial finite element model (FLUX). The excitation used produces a uniform magnetic field on the plate under test in the absence of defects and the disturbances due to the defects are compared with those obtained from experimental measurements. In order to increase the limited penetration depth of the method giant magnetoresistors (GMR) are used to lower the working frequency. The geometry of the excitation planar coil produces a uniform magnetic field on an area of around the GMR sensor, inducing a uniform eddy current distribution on the plate. In the presence of defects in the material surface, the lines of currents inside the material are deviated from their uniform direction and the magnetic field produced by these currents is sensed by the GMR sensor. Besides the theoretical study of the electromagnetic system, the paper describes the experiments that have been carried out to support the theory and conclusions are drawn for cracks having different depths.
- Published
- 2014
35. Digital Shearography and vibration excitation for NDT of aircraft components
- Author
-
Dirk Findeis and Jasson Gryzagoridis
- Subjects
Engineering ,business.industry ,Acoustics ,Inspection method ,Structural engineering ,Laser ,law.invention ,Vibration ,Stress (mechanics) ,Interferometry ,Shearography ,law ,Nondestructive testing ,business ,Excitation - Abstract
Digital Shearography is a laser based inspection method, capable of determining minute surface displacement gradients in response to an applied stress. The non-contacting technique is based on interferometric principles, and produces whole field results. As a result the method has been adapted for defect detection purposes of high value components in the NDT/E industry. In order to obtain an object’s surface displacement gradient when applying Digital Shearography, the object has to be stressed. This paper investigates the use of vibration excitation as a stressing technique for the inspection of selected composite aircraft components. The theory of digital Shearography is presented, the inspections using a piezo based vibration probe is outlined, and the results obtained are displayed. A discussion of the results obtained concludes the paper.
- Published
- 2014
36. Comparison of intrinsic width for InGaAs PIN photodiode
- Author
-
Mohd Azlishah Othman, R. A. Ramlee, H. A. Sulaiman, Z. A. F. M. Napiah, N. Y. M. Yasin, M. H. Misran, M. A. Meor Said, and M. M. Ismail
- Subjects
Optics ,Semiconductor ,Materials science ,Dopant ,business.industry ,law ,Optoelectronics ,business ,Photodiode ,law.invention - Abstract
This paper presents comparison on the different intrinsic width of InGaAs PIN Photodiode. Intrinsic region is a pure semiconductor without any significant dopant species present. In this paper, it will present two different sizes of the intrinsic region for InGaAs PIN Photodiode. This photodiode will be designed by using Atlas Silvaco TCAD Tools. From the structure, the characteristics of the photodiode will be analyzed. The I-layer thickness (or width) is varied from 5μm × 20μm to 8μm × 20μm in order to investigate its effects on the current-voltage (IV) characteristics. These papers are separated into several sections consists of the basic principle, characteristics, advantages and the recent technologies of PIN Photodiode. There will be a specific section on comparison between different intrinsic widths of InGaAs PIN Photodiode.
- Published
- 2014
37. On the use of optical fiber Bragg grating (FBG) sensor technology for strain modal analysis
- Author
-
Francisco Araujo, Andreia Pereira, Bart Peeters, and Fabio Luis Marques dos Santos
- Subjects
Optical fiber ,Materials science ,business.industry ,Acoustics ,Modal analysis ,Structural engineering ,Accelerometer ,law.invention ,Vibration ,Fiber Bragg grating ,law ,Measuring principle ,Helicopter rotor ,business ,Strain gauge - Abstract
This paper discusses the use of optical fiber Bragg grating (FBG) strain sensors for structural dynamics measurements. For certain industrial applications, there is an interest to use strain sensors rather than or in combination with accelerometers for experimental modal analysis. Classical electrical strain gauges can be used hereto, but optical strain sensors are an interesting alternative with some very specific advantages. This paper gives an overview of dynamic strain measurements in industrial applications, discusses the benefits of FBG sensors and reviews their measurement principle. Finally, the concept of strain modal analysis is introduced and a helicopter main rotor blade vibration testing and analysis case study is presented.
- Published
- 2014
38. Cryogenic systems for proof of the principle experiment of coherent electron cooling at RHIC
- Author
-
Jean Clifford Brutus, Yuenian Huang, Roberto Than, Sergey Belomestnykh, Paul Orfin, V. Soria, John Skaritka, T. Tallerico, and D. Lederle
- Subjects
Physics ,Ion beam ,business.industry ,Liquid helium ,Superconducting radio frequency ,Electrical engineering ,chemistry.chemical_element ,Particle accelerator ,law.invention ,Optics ,chemistry ,law ,Physics::Accelerator Physics ,business ,Relativistic Heavy Ion Collider ,Helium ,Electron cooling ,Electron gun - Abstract
The Coherent electron Cooling (CeC) Proof of Principle (PoP) experiment is proposed to be installed in the Relativistic Heavy Ion Collider (RHIC) to demonstrate proton and ion beam cooling with this new technique that may increase the beam luminosity in certain cases, by as much as tenfold. Within the scope of this project, a 112 MHz, 2MeV Superconducting Radio Frequency (SRF) electron gun and a 704 MHz 20MeV 5-cell SRF cavity will be installed at IP2 in the RHIC ring. The superconducting RF electron gun will be cooled in a liquid helium bath at 4.4 K. The 704 MHz 5-cell SRF cavity will be cooled in a super-fluid helium bath at 2.0 K. This paper discusses the cryogenic systems designed for both cavities. For the 112 MHz cavity cryogenic system, a condenser/boiler heat exchanger is used to isolate the cavity helium bath from pressure pulses and microphonics noise sources. For the 704 MHz 5-cell SRF cavity, a heat exchanger is also used to isolate the SRF cavity helium bath from noise sources in the sub-atmospheric pumping system operating at room temperature. Detailed designs, thermal analyses and discussions for both systems will be presented in this paper.
- Published
- 2014
39. Nonlinear eddy current NDE and theory based on vector Preisach model in Rayleigh regime
- Author
-
Norio Nakagawa
- Subjects
Weight function ,Mathematical analysis ,Extension (predicate logic) ,law.invention ,Harmonic analysis ,Nonlinear system ,symbols.namesake ,law ,Control theory ,Eddy current ,symbols ,Rayleigh scattering ,Born approximation ,Constant (mathematics) ,Mathematics - Abstract
This paper presents a nonlinear theory of eddy current NDE response, applicable to EC measurements involving ferromagnetic materials. The theory treats the nonlinearity at the lowest nontrivial order. At this lowest order, the well-known Rayleigh relation exists, describing the non-linear hysteretic B-H relation, except that it is restricted to the case where the B and H fields are unidirectional and parallel to each other. Prototypical EC NDE problems require extension of Rayleigh's formula for vector-valued B and H fields. The paper examines a vector Preisach model, and points out that the vector extension of the Rayleigh relation is obtainable by the choice of a constant weight function. The given Preisach-Rayleigh model is amenable to explicit harmonic analysis, through which NLEC problems are soluble in Born approximation.
- Published
- 2014
40. Integration of microwave and thermographic NDT methods for corrosion detection
- Author
-
Dustin F. Pieper, Kristen M. Donnell, Mohammad Tayeb Ghasr, and Edward C. Kinzel
- Subjects
Engineering ,Induction heating ,business.industry ,Rebar ,Mechanical engineering ,Structural engineering ,Corrosion ,law.invention ,law ,Nondestructive testing ,Thermography ,Microwave nondestructive testing ,Transportation industry ,business ,Microwave - Abstract
Infrastructure health monitoring is an important issue in the transportation industry. For the case of cement-based structures in particular, detection of corrosion on reinforcing steel bars (rebar) is an ongoing problem for aging infrastructure. There have been a number of techniques that have shown promise in this area including microwave nondestructive testing (NDT) and thermography. Thermography is quite advantageous as it is an established method, and can be utilized for large inspection areas with intuitive results. Typical heat sources include induction heating and flash lamps, but these are not without drawbacks. Microwave nondestructive testing has also been successful at detecting corroded rebar, but at the cost of lengthy scan times. This paper presents an investigation into the potential of utilizing aspects of microwave NDT and thermography to create a hybrid NDT method, herein referred to as Active Microwave Thermography (AMT). AMT takes advantage of the electromagnetically lossy nature of corrosion byproducts and uses microwave energy to induce heat in the corrosion. Subsequently, the resultant heat profile is captured using an infrared camera. This paper presents initial simulations and measurements that highlight the potential of AMT to detect corroded rebar.
- Published
- 2014
41. A new technique to measure the thickness of micromachined structures using an optical microscope
- Author
-
Nor Hisham Hamid, Asfand Yar, John Ojur Dennis, M. H. Md Khir, and Faiz Ahmad
- Subjects
Depth of focus ,Materials science ,Thin layers ,Silicon ,business.industry ,chemistry.chemical_element ,law.invention ,Optics ,chemistry ,CMOS ,Optical microscope ,law ,Horizontal position representation ,Reference surface ,Vertical displacement ,business - Abstract
This paper presents a quick and straightforward method to measure the thickness of the micro structures using optical microscope. In optical microscopy, for depth of focus (DOF) method there are two surfaces required, one as a reference. In case of live dies specially in CMOS MEMS the thickness of silicon attached to the CMOS thin layers can't be find accurately because of unavailability of reference surface. The main focus of this paper is the measurement of thickness of silicon attached to the CMOS thin layers as well as CMOS layers itself specially in the broken form. Normally thickness is the vertical displacement of the structures but when these structures are broken it very hard to clamp the microstructures in horizontal position that is why a special sample holder is prepared and reported and sample holding technique to hold the samples in the horizontal position is introduced. Leica DM 12000 optical microscope is used to measure and mark the thickness of CMOS layers and silicon attached to these layers.
- Published
- 2014
42. Thermo-mechanical analyses of ITER in-vessel magnetic sensor assembly
- Author
-
A. Rizzolo, S. Peruzzo, S. Arshad, W. Gonzalez, G. Vayakis, and M. Portales
- Subjects
Materials science ,Mechanical engineering ,Thermal contact ,Welding ,Deformation (meteorology) ,Signal ,Finite element method ,law.invention ,Stress (mechanics) ,law ,visual_art ,Electronic engineering ,visual_art.visual_art_medium ,Head (vessel) ,Ceramic - Abstract
This paper summarizes the work concerning design studies of the ITER in-vessel discrete magnetic sensor assemblies, with particular emphasis on the thermal behaviour of the Low Temperature Co-fired Ceramic (LTCC) magnetic sensor and on the thermo-mechanical aspects of the interface with the Vacuum Vessel (VV). The paper summarises the results of FEM thermal analyses performed on the LTCC sensor head and on the sensor assembly to assess the temperature distribution during operating conditions, which could affect the sensor signal due to Temperature-Induced Electromotive Force effect. The paper then concentrates on mechanical analysis of the Base-Plate to assess that the stress and deformation due to the welding to the VV are acceptable to guarantee a sound installation and a suitable thermal contact of the sensor assembly to the VV.
- Published
- 2014
43. Superior model for fault tolerance computation in designing nano-sized circuit systems
- Author
-
N. S. S. Singh, M. S. Muthuvalu, and V. S. Asirvadam
- Subjects
Computational complexity theory ,Computer science ,Probabilistic logic ,Fault tolerance ,Integrated circuit ,law.invention ,Reliability engineering ,CMOS ,law ,MATLAB ,computer ,Reliability (statistics) ,Electronic circuit ,computer.programming_language - Abstract
As CMOS technology scales nano-metrically, reliability turns out to be a decisive subject in the design methodology of nano-sized circuit systems. As a result, several computational approaches have been developed to compute and evaluate reliability of desired nano-electronic circuits. The process of computing reliability becomes very troublesome and time consuming as the computational complexity build ups with the desired circuit size. Therefore, being able to measure reliability instantly and superiorly is fast becoming necessary in designing modern logic integrated circuits. For this purpose, the paper firstly looks into the development of an automated reliability evaluation tool based on the generalization of Probabilistic Gate Model (PGM) and Boolean Difference-based Error Calculator (BDEC) models. The Matlab-based tool allows users to significantly speed-up the task of reliability analysis for very large number of nano-electronic circuits. Secondly, by using the developed automated tool, the paper explores into a comparative study involving reliability computation and evaluation by PGM and, BDEC models for different implementations of same functionality circuits. Based on the reliability analysis, BDEC gives exact and transparent reliability measures, but as the complexity of the same functionality circuits with respect to gate error increases, reliability measure by BDEC tends to be lower than the reliability measure by PGM. The lesser reliability measure by BDEC is well explained in this paper using distribution of different signal input patterns overtime for same functionality circuits. Simulation results conclude that the reliability measure by BDEC depends not only on faulty gates but it also depends on circuit topology, probability of input signals being one or zero and also probability of error on signal lines.
- Published
- 2014
44. Using fiberglass volumes for VPI of superconductive magnetic systems’ insulation
- Author
-
Dmitry Stepanov, A. S. Bursikov, I. Y. Rodin, A. A. Bezrukov, Y. A. Klimchenko, E. L. Marushin, I. S. Andreev, A. A. Mednikov, and A. B. Pischugin
- Subjects
Materials science ,Electromagnet ,business.industry ,Vacuum pressure ,Iter tokamak ,Electrical engineering ,Superconducting magnet ,Materials testing ,law.invention ,Electromagnetic coil ,law ,Electrical equipment ,Magnet ,Composite material ,business - Abstract
The paper describes the method of manufacturing fiberglass molds for vacuum pressure impregnation (VPI) of high-voltage insulation of superconductive magnetic systems (SMS) with epoxidian hot-setting compounds. The basic advantages of using such vacuum volumes are improved quality of insulation impregnation in complex-shaped areas, and considerable cost-saving of preparing VPI of large-sized components due to dispensing with the stage of fabricating a metal impregnating volume. Such fiberglass vacuum molds were used for VPI of high-voltage insulation samples of an ITER reactor’s PF1 poloidal coil. Electric insulation of these samples has successfully undergone a wide range of high-voltage and mechanical tests at room and cryogenic temperatures. Some results of the tests are also given in this paper.
- Published
- 2014
45. Performance analysis of InGaAs/InP avalanche photodiode by using different guard ring structures
- Author
-
Mohd Azlishah Othman, Mohd Nor Hussain, Maizatul Alice Meor Said, Zul Atfyi Fauzan Mohamed Napiah, Siti Nabilah Taib, Mohd Muzafar Ismail, and M. H. Misran
- Subjects
Materials science ,Avalanche diode ,APDS ,business.industry ,Doping ,Substrate (electronics) ,Avalanche photodiode ,law.invention ,law ,Electric field ,Optoelectronics ,Breakdown voltage ,business ,Sensitivity (electronics) - Abstract
Avalanche Photodiode based on InGaAs/InP was chosen because of the needs of high speed optical receivers and have their own advantages on high sensitivity. In this project, we focused on the effect of guard ring on InGaAs/InP avalanche photodiodes and its performance. Three types of guard ring structures are designed in APD and their current-voltage (I-V) characteristics (electric field profiles) are simulated and analyzed. In this paper, the characteristics of guard ring in InGaAs/InP are investigated using Silvaco software, TCAD tools. This paper investigates the effects of guard-ring (GR) structures on the performance of InGaAs/InP avalanche photodiode (APDs) designed in Silvaco TCAD. Three type InGaAs/InP-APDs based on P+/N-well guard ring, n+/p-substrate guard ring and no presence guard ring are designed and their electric field profiles are simulated. In others to know the best structures of InGaAs/InP avalanche photodiode structures, the current-voltage characteristics (I-V characteristics) are measured and compared. Overall, the project includes the effect and relationship of avalanche photodiode between substrate concentrations and doping, type of materials, with the breakdown voltage and leakage current were investigated. Then, the structure is applied with guard ring structure. At the end, we choose the best optimized design of avalanche photodiode based on current-voltage characteristics. From the theoretical, they conclude the important of guard ring presence in the avalanche photodiode structure in order to avoid premature breakdown and also leakage current. From the experiment, we can conclude that the best structures of InGaAs/InP avalanche photodiode is by using P+/N-well guard ring because this structure give the higher breakdown voltage and lowest leakage current.
- Published
- 2014
46. Experimental validation of an eddy current probe for defect detection in thick conducting specimen
- Author
-
P Mahesh Raja, Kavitha Arunachalam, and Krishnan Balasubramanian
- Subjects
Materials science ,Analytical chemistry ,chemistry.chemical_element ,Penetration (firestop) ,Experimental validation ,law.invention ,Lift (force) ,chemistry ,Aluminium ,Electromagnetic coil ,law ,Slab ,Eddy current ,Air core ,Composite material - Abstract
This paper presents numerical modeling and experimental measurements of eddy current (EC) probe for detecting subsurface defects in 10 mm to 15 mm thick conducting specimen. Measurements are presented for a pancake air core coil to detect subsurface defect in 10 mm thick aluminum slab. EC coil parameters namely inner radius(r1), and outer radius(r2), and operating frequency (f) are optimized for deeper penetration in the conducting plate (35 MS/m) for a given coil height(h), and lift off distance (d). Preliminary simulation results are presented for a subsurface defect in 15 mm thick aluminium plate for the optimized EC coil parameters.
- Published
- 2016
47. Experimental study of the acoustoelastic Lamb wave in thin plates
- Author
-
Leonard J. Bond and Ning Pei
- Subjects
Materials science ,business.industry ,Acoustics ,Structural engineering ,Welding ,law.invention ,Stress (mechanics) ,Time of flight ,Lamb waves ,Residual stress ,law ,Ultrasonic sensor ,Texture (crystalline) ,Sensitivity (control systems) ,business - Abstract
Many factors can cause residual stresses in industry, like rolling, welding and coating. Residual stresses can have both benefits and shortcomings on components, so it is important to find the residual stresses out and enhance its benefits part and get rid of its harmful part. There are many methods for residual stresses detection and ultrasonic method turns out to be a good one for it is nondestructive, relative cheap and portable. The critically refracted longitudinal (LCR) wave is widely used for it is regarded most sensitive to stress and less sensitive to texture which can influence detection results. Ultrasonic methods for residual stresses detection are based on time of flight (TOF) measurement, but because the measurement should reach nanosecond to show stress change, there are many other factors that can influence TOF, like temperature, texture of the components and even the thickness of the couplant. So increasing the TOF’s sensitivity to stress is very important. In this paper the relationships between velocity and frequency are studied experimentally[6] for different Lamb modes, under various stress loadings. The result shows that the sensitivity of different modes various a lot, the A1 mode is the most sensitivity, compared to S0, S1 and A0 modes; if the force is added to 100 MPa, the change stress of A1 mode can be as large to 80 m/s, which is about 10 times more sensitive than the traditional bulk wave. This makes it as a good choice for residual stress detection.
- Published
- 2016
48. Additive manufacturing metrology: State of the art and needs assessment
- Author
-
Leonard J. Bond, Joseph N. Gray, Hossein Taheri, Daniel J. Barnard, and Lucas W. Koester
- Subjects
Rapid prototyping ,Flexibility (engineering) ,Engineering ,Standardization ,Process (engineering) ,business.industry ,3D printing ,Mechanical engineering ,Manufacturing engineering ,law.invention ,law ,Production (economics) ,Process control ,business ,Stereolithography - Abstract
Additive manufacturing (AM) is a technology that first emerged in 1987 with stereolithography (SL) of plastic materials from 3D Systems. It saw light use for rapid prototyping and very low volume production for a number of years. However, in the past few years AM of metallic materials has become a practical fabrication technology, use is rapidly increasing and is projected to continue with double digit growth in coming years. The promise and flexibility shown by AM has spurred efforts to begin standardization of this type of process. This paper provides an assessment of the state of the art for in-situ process monitoring of AM processes with an emphasis on the production of metallic components. It is seen that with the implementation of proper process control there is potential to create reliable and reproducible materials and geometries previously unachievable using metal removal based means of production. A reliable methodology for detection and control of microstructure and defects would be of great value in terms of enabling broader AM utilization.
- Published
- 2016
49. Design of a multi beam klystron cavity from its single beam parameters
- Author
-
Vijay Janyani, Deepender Kant, and L. M. Joshi
- Subjects
Physics ,Klystron ,Single beam ,business.industry ,Electrical engineering ,Electron ,Kinetic energy ,law.invention ,Optics ,law ,Cathode ray ,Physics::Accelerator Physics ,Radio frequency ,Laser beam quality ,business ,Beam (structure) - Abstract
The klystron is a well-known microwave amplifier which uses kinetic energy of an electron beam for amplification of the RF signal. There are some limitations of conventional single beam klystron such as high operating voltage, low efficiency and bulky size at higher power levels, which are very effectively handled in Multi Beam Klystron (MBK) that uses multiple low purveyance electron beams for RF interaction. Each beam propagates along its individual transit path through a resonant cavity structure. Multi-Beam klystron cavity design is a critical task due to asymmetric cavity structure and can be simulated by 3D code only. The present paper shall discuss the design of multi beam RF cavities for klystrons operating at 2856 MHz (S-band) and 5 GHz (C-band) respectively. The design approach uses some scaling laws for finding the electron beam parameters of the multi beam device from their single beam counter parts. The scaled beam parameters are then used for finding the design parameters of the multi beam c...
- Published
- 2016
50. NB-PLC channel modelling with cyclostationary noise addition & OFDM implementation for smart grid
- Author
-
Karunesh Kumar Gupta and Togis Thomas
- Subjects
Orthogonal frequency-division multiplexing ,business.industry ,Computer science ,Cyclostationary process ,Electrical engineering ,020206 networking & telecommunications ,02 engineering and technology ,law.invention ,Power-line communication ,Smart grid ,Narrowband ,law ,0202 electrical engineering, electronic engineering, information engineering ,Bit error rate ,business ,Transformer ,Low voltage ,Communication channel - Abstract
Power line communication (PLC) technology can be a viable solution for the future ubiquitous networks because it provides a cheaper alternative to other wired technology currently being used for communication. In smart grid Power Line Communication (PLC) is used to support communication with low rate on low voltage (LV) distribution network. In this paper, we propose the channel modelling of narrowband (NB) PLC in the frequency range 5 KHz to 500 KHz by using ABCD parameter with cyclostationary noise addition. Behaviour of the channel was studied by the addition of 11KV/230V transformer, by varying load location and load. Bit error rate (BER) Vs signal to noise ratio SNR) was plotted for the proposed model by employing OFDM. Our simulation results based on the proposed channel model show an acceptable performance in terms of bit error rate versus signal to noise ratio, which enables communication required for smart grid applications.
- Published
- 2016
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