501 results
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2. Fabrication of porous ceramic via recycling of glass with paper fiber as sacrificial fugitive
- Author
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Badarulzaman, N. A., primary, Hamidon, A., additional, and Nor, M. A. A. M., additional
- Published
- 2015
- Full Text
- View/download PDF
3. Analysis of light scattering by two-dimensional inhomogeneities in paper using general radiative transfer theory
- Author
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Nukala, Madhuri, primary and Mendrok, Jana, additional
- Published
- 2014
- Full Text
- View/download PDF
4. Nanotechnologies for cultural heritage: Nanodiamond for conservation of papers and parchments
- Author
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Emanuela Tamburri, Giacomo Reina, Maria Letizia Terranova, and Silvia Orlanducci
- Subjects
Settore CHIM/03 - Chimica Generale e Inorganica ,papers ,Materials science ,conservation ,nanodiamond ,cultrural heritage ,parchments ,Nanotechnology ,Nanodiamond ,Artificial aging - Abstract
In this paper we report some tests regarding the feasibility of nanodiamond to act as a cleaning/consolidation agent of papers and parchments. We carried out a series of treatments aiming to develop innovative approaches for de-acidification, cleaning and consolidation. Dispersions of nanodiamond have been used as de-acidification agents of ancient papers showing the ability to sensibly reduce the acidity of the paper without using any alkaline base. Similar dispersions have been used for cleaning processes and nanodiamond demonstrated an outstanding capability to clean ancient papers and parchments avoiding the use of any solvent and surfactant. Moreover interesting results were obtained by using nanodiamond as consolidation agent. In particular, artificial aging by UV exposition was appreciably contrasted when samples were preliminarily submitted to a treatment by nanodiamond. This outcome was demonstrated in papers and parchments by Raman spectroscopy analyses that evidenced the property of nanodiamond to be an excellent UV-scavenger.
- Published
- 2014
5. Learning algebra on screen and on paper: The effect of using a digital tool on students’ understanding
- Author
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Paul Drijvers, Marja van den Heuvel-Panhuizen, and Al Jupri
- Subjects
Initial algebra ,Computer science ,Students understanding ,computer.software_genre ,Algebra ,Variable (computer science) ,Qualitative analysis ,ComputingMilieux_COMPUTERSANDEDUCATION ,Mathematics education ,Data analysis ,Algebra over a field ,Java applet ,computer ,Equation solving - Abstract
The use of digital tools in algebra education is expected to not only contribute to master skill, but also to acquire conceptual understanding. The question is how digital tools affect students” thinking and understanding. This paper presents an analysis of data of one group of three grade seventh students (12-13 year-old) on the use of a digital tool for algebra, the Cover-up applet for solving equations in particular. This case study was part of a larger teaching experiment on initial algebra enriched with digital technology which aimed to improve students” conceptual understanding and skills in solving equations in one variable. The qualitative analysis of a video observation, digital and written work showed that the use of the applet affects student thinking in terms of strategies used by students while dealing with the equations. We conclude that the effects of the use of the digital tool can be traced from student problem solving strategies on paper-and-pencil environment which are similar to strategies while working with the digital tool. In future research, we recommend to use specific theoretical lenses, such as the theory of instrumental genesis and the onto-semiotic approach, to reveal more explicit relationships between students” conceptual understanding and the use of a digital tool.
- Published
- 2016
6. Photoluminescence of patterned CdSe quantum dot for anti-counterfeiting label on paper
- Author
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Nursidik Yulianto, Isnaeni, and Maria Margaretha Suliyanti
- Subjects
Blue laser ,Full width at half maximum ,Wavelength ,Materials science ,Optics ,Photoluminescence ,Quantum dot ,business.industry ,Optoelectronics ,Emission spectrum ,business ,Nanocrystalline material ,Spectral line - Abstract
We successfully developed a method utilizing colloidal CdSe nanocrystalline quantum dot for anti-counterfeiting label on a piece of glossy paper. We deposited numbers and lines patterns of toluene soluble CdSe quantum dot using rubber stamper on a glossy paper. The width of line pattern was about 1-2 mm with 1-2 mm separation between lines. It required less than one minute for deposited CdSe quantum dot on glossy paper to dry and become invisible by naked eyes. However, patterned quantum dot become visible using long-pass filter glasses upon excitation of UV lamp or blue laser. We characterized photoluminescence of line patterns of quantum dot, and we found that emission boundaries of line patterns were clearly observed. The error of line size and shape were mainly due to defect of the original stamper. The emission peak wavelength of CdSe quantum dot was 629 nm. The emission spectrum of deposited quantum dot has full width at half maximum (FWHM) of 30-40 nm. The spectra similarity between deposited quant...
- Published
- 2016
7. Application of metal magnetic memory technology on defects detection of jack-up platform
- Author
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Cheng Liping, Changhang Xu, Jing Xie, Guoming Chen, and Xiaokang Yin
- Subjects
Engineering ,Oil exploration ,business.industry ,Feature extraction ,Hash function ,Magnetic memory ,Paper based ,Structural health monitoring ,Bearing capacity ,Structural engineering ,business ,Automotive engineering ,Stress concentration - Abstract
Metal magnetic memory test (MMMT), which is an effective way in evaluating early damages of ferrimagnets, can determine the existence of material stresses concentration and premature defects. As one of offshore oil exploration and development equipment, jack-up platform always generate stress concentration during its life-cycle due to complicated loading condition and the hash marine environment, which will decline the bearing capacity and cause serious consequences. The paper conducts in situ experiments of defects detection on some key structural components of jack-up platform using MMMT. The signals acquired by MMM-System are processed for feature extraction to evaluate the severity of structure stress concentration. The results show that the method presented in this paper based on MMMT can provide an effective and convenient way of defect detection and structural health monitoring for Jack-up Platform.
- Published
- 2016
8. Developing particulate thin filter using coconut fiber for motor vehicle emission
- Author
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S. Riyanto, Unggul P. Juswono, and Arinto Y. P. Wardoyo
- Subjects
Human health ,Particle emission ,Waste management ,Filter (video) ,Coming out ,Particle ,Environmental science ,Fiber ,Particulates ,Pulp and paper industry - Abstract
Amounts of motor vehicles in Indonesia have been recognized a sharply increase from year to year with the increment reaching to 22 % per annum. Meanwhile motor vehicles produce particulate emissions in different sizes with high concentrations depending on type of vehicles, fuels, and engine capacity. Motor Particle emissions are not only to significantly contribute the atmosphric particles but also adverse to human health. In order to reduce the particle emission, it is needed a filter. This study was aimed to develop a thin filter using coconut fiber to reduce particulate emissions for motor vehicles. The filter was made of coconut fibers that were grinded into power and mixed with glues. The filter was tested by the measurements of particle concentrations coming out from the vehicle exhaust directly and the particle concentrations after passing through the filter. The efficiency of the filter was calculated by ratio of the particle concentrations before comming in the filter to the particle conentrations after passing through the filter. The results showed that the efficiency of the filter obtained more than 30 %. The efficiency increases sharply when a number of the filters are arranged paralelly.
- Published
- 2016
9. Additives for cement compositions based on modified peat
- Author
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N. O. Kopanitsa, Aleksandra Gorshkova, Olga Demyanenko, and Yurij Sarkisov
- Subjects
Cement ,Materials science ,Peat ,Economic situation ,Mineralogy ,Mortar ,Raw material ,Pulp and paper industry ,Experimental research - Abstract
High quality competitive dry building mixes require modifying additives for various purposes to be included in their composition. There is insufficient amount of quality additives having stable properties for controlling the properties of cement compositions produced in Russia. Using of foreign modifying additives leads to significant increasing of the final cost of the product. The cost of imported modifiers in the composition of the dry building mixes can be up to 90% of the material cost, depending on the composition complexity. Thus, the problem of import substitution becomes relevant, especially in recent years, due to difficult economic situation. The article discusses the possibility of using local raw materials as a basis for obtaining dry building mixtures components. The properties of organo-mineral additives for cement compositions based on thermally modified peat raw materials are studied. Studies of the structure and composition of the additives are carried out by physicochemical research methods: electron microscopy and X-ray analysis. Results of experimental research showed that the peat additives contribute to improving of cement-sand mortar strength and hydrophysical properties.
- Published
- 2016
10. Characterization of an expansive clay treated with lime: Effect of compaction on the swelling pressure
- Author
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A. Nechnech and Z. Kechouane
- Subjects
Materials science ,Expansive clay ,Compaction ,Swelling pressure ,Proctor compaction test ,engineering.material ,Pulp and paper industry ,complex mixtures ,Bentonite ,Soil water ,medicine ,engineering ,Geotechnical engineering ,Swelling ,medicine.symptom ,Lime - Abstract
This work focuses on the study of the compaction effect on the stabilization of a highly expansive clay soil by adding lime. To this end, we used two types of swelling clay soils, the first one is intact and the other derivative (reconstituted, prepared from a natural soil and bentonite mixture with the following proportions: 70 and 30%. The results of the recorded œdometric tests show that the incorporation of the lime reduces the soil swelling pressures at each dosing lime in agreement with many reported previous studies. The contents of lime greatly affect swelling; indeed for a dosage of 6% lime the swelling pressures are reduced by 27% for the sample of disturbed soil. The compaction test performed on the reconstituted incorporated lime soil shows that for a dosage of 2% lime, we have a reduction of the swelling pressure of 96%.
- Published
- 2015
11. Comparison of lime powder and caustic soda as a pre-treatment for ammonia-nitrogen removal from a scheduled waste leachate
- Author
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A. Sani, C. M. Hasfalina, M. L. Nurul Hanira, and Mohd. Rashid
- Subjects
inorganic chemicals ,Pre treatment ,chemistry.chemical_classification ,Materials science ,Waste management ,engineering.material ,Pulp and paper industry ,Ammonia nitrogen ,Ammonia ,chemistry.chemical_compound ,Wastewater ,chemistry ,engineering ,Coagulation (water treatment) ,Organic matter ,Leachate ,Lime - Abstract
Studies on leachate taken from scheduled waste landfill are limited. This might be due to the complex characteristics of the leachate from scheduled waste landfill compared to other types of landfills. Leachate is known as a strong wastewater in terms of its organic matter and ammonia content. In this study, a pre-treatment on the removal of ammonia-nitrogen (NH3-N) by coagulation on a leachate sample taken from a Scheduled Waste Landfill (SWL) is reported. The coagulation was performed using lime (Ca (OH)2), and caustic soda (NaOH) with varying pH and amount of coagulant. A different dosage of Ca (OH)2, and NaOH was applied and the removal efficiency using both coagulants were investigated to find the most optimum dosage for NH3-N removal. Results showed that the percentage of NH3-N removal was relatively the same for both Ca (OH)2 and NaOH which was up to 45% and 48%, respectively. The optimum pH and dosage of coagulant for the removal process using Ca (OH)2 was pH=12.40±0.02 and 6gL−1, respectively while with NaOH was pH=12.83±0.02 and 8 gL−1, respectively. A small difference in the removal of NH3-N with a less dosage of coagulant used in the study suggests that lime (Ca(OH)2), is a better choice for the pre-treatment process.
- Published
- 2015
12. Kinetic study of enzymatic hydrolysis of acid-pretreated coconut coir
- Author
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Rudy Agustriyanto and Akbarningrum Fatmawati
- Subjects
chemistry.chemical_classification ,Materials science ,Waste management ,biology ,food and beverages ,Biomass ,Cellulase ,Pulp and paper industry ,Reducing sugar ,Hydrolysis ,chemistry.chemical_compound ,chemistry ,Enzymatic hydrolysis ,biology.protein ,Cellulose ,Coir ,Sugar - Abstract
Biomass waste utilization for biofuel production such as bioethanol, has become more prominent currently. Coconut coir is one of lignocellulosic food wastes, which is abundant in Indonesia. Bioethanol production from such materials consists of more than one step. Pretreatment and enzymatic hydrolysis is crucial steps to produce sugar which can then be fermented into bioethanol. In this research, ground coconut coir was pretreated using dilute sulfuric acid at 121°C. This pretreatment had increased the cellulose content and decreased the lignin content of coconut coir. The pretreated coconut coir was hydrolyzed using a mix of two commercial cellulase enzymes at pH of 4.8 and temperature of 50°C. The enzymatic hydrolysis was conducted at several initial coconut coir slurry concentrations (0.1-2 g/100 mL) and reaction times (2-72 hours). The reducing sugar concentration profiles had been produced and can be used to obtain reaction rates. The highest reducing sugar concentration obtained was 1,152.567 mg/L, w...
- Published
- 2015
13. Development, characterization and potential applications of edible film from seaweed (Kappaphycus alvarezii)
- Author
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Siah Watt Moey, Ishak Ahmad, and Aminah Abdullah
- Subjects
Horticulture ,chemistry.chemical_compound ,Oxygen permeability ,Materials science ,Kappaphycus alvarezii ,biology ,chemistry ,Film processing ,Ultimate tensile strength ,Pulp and paper industry ,biology.organism_classification ,Carrageenan - Abstract
A new patent pending process is proposed in this study to produce edible film directly from seaweed (Kappaphycus alvarezii). Seaweed together with other ingredients had been used to produce the film through casting technique. Physical and mechanical tests were performed on the edible film to examine the thickness, colour, transparency, solubility, tensile strength, elongation at break, water permeability rate, oxygen permeability rate and surface morphology. The produced film was transparent, stretchable, sealable and have basic properties for applications in food, pharmaceutical, cosmetic, toiletries and also agricultural industries. Edible film was successfully developed directly from dry seaweed instead of using alginate and carrageenan. The edible film processing method developed in this research was easier and cheaper compared with the method by using alginate and carrageenan.
- Published
- 2014
14. Coagulation-flocculation in leachate treatment using modified micro sand
- Author
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Nur Hanani Thaldiri and Azhar Abdul Halim
- Subjects
Suspended solids ,Flocculation ,Materials science ,Wastewater ,Settling ,Chemical oxygen demand ,Environmental engineering ,medicine ,Coagulation (water treatment) ,Leachate ,Pulp and paper industry ,Chloride ,medicine.drug - Abstract
Sanitary landfill leachate is considered as highly polluted wastewater, without any treatment, discharging into water system will cause underground water and surface water pollutions. This study was to investigate the treatability of the semi-aerobic landfill leachate via coagulation-flocculation using poly-aluminum chloride (PAC), cationic polymer, and modified micro sand. Leachate was collected from Pulau Burung Sanitary Landfill (PBSL) located in Penang, Malaysia. Coagulation-flocculation was performed by using jar test equipment and the effect of pH, dose of coagulant and dose of polymer toward removal of chemical oxygen demand (COD), color and suspended solid (SS) were examined. Micro sand was also used in this study to compare settling time of coagulation-flocculation process. The optimum pH, dose of coagulant (PAC) and dose of polymer (cationic) achieved were 7.0, 1000 mg/L and 8 mg/L, respectively. The dose of micro sand used for the settling time process was 300 mg/L. Results showed that 52.66% removal of COD, 97.16% removal of SS and 96.44% removal of color were achieved under optimum condition. The settling times for the settling down of the sludge or particles that formed during coagulation-flocculation process were 1 min with modified sand, 20 min with raw micro sand and 45 min without micro sand.
- Published
- 2013
15. Life cycle inventory for palm based plywood: A gate-to-gate case study
- Author
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Shamim Ahmad, Halimah Muhamad, Ismail Sahid, Vijaya Subramaniam, and Anis Mokhtar
- Subjects
Engineering ,business.industry ,World market ,Palm oil ,Biomass ,business ,Palm ,Pulp and paper industry ,Moisture resistance ,Life-cycle assessment ,Life cycle inventory - Abstract
The oil palm industry heavily relies on the world market. It is essential to ensure that the oil palm industry is ready to meet the demands and expectation of these overseas customers on the environmental performance of the oil palm industry. Malaysia produces 13.9 million tons of oil palm biomass including oil palm trunk (OPT), frond and empty fruits bunches (EFB) annually. OPT felled in some oil palm plantations during replanting is transported to various industries and one such industry is the plywood factories. In order to gauge the environmental performance of the use of OPT as plywood a Life Cycle Assessment (LCA) study was conducted for palm based plywood. LCA is an important tool to assess the environmental performance of a product or process. Life cycle inventory (LCI) is the heart of a LCA study. This LCI study has a gate-to-gate system boundary and the functional unit is 1 m3 palm plywood produced and covers three types of plywood; Moisture Resistance Plywood (MR), Weather Boiling Proof Plywood...
- Published
- 2013
16. The features of ceramic materials structure formation when using hard-melting wastes of thermal power stations in charge stock
- Author
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Viktoriya Litvinova, Alexander Lutsenko, Ivan Yu. Yuriev, and Nelli Skripnikova
- Subjects
Materials science ,Structure formation ,visual_art ,Aluminum silicate ,Metallurgy ,visual_art.visual_art_medium ,Thermal power station ,Mineralogy ,Sintering ,Ceramic ,Shrinkage - Abstract
The paper presents the analysis of aluminum silicate waste generated by thermal power station of the city of Seversk, Tomsk region, Russia. The chemical compositions of aluminum silicate waste are detected and the efficient mixture compositions with the addition of aluminum silicate waste are suggested herein. Ceramic brick structure formation is studied in this paper using X-ray phase and SEM analyses. It is identified that the formed vitreous phase facilitates such strengthening structural modifications as sintering out of pores and shrinkage of unmelted aluminum silicate particles with the following formation of a monolithic product.
- Published
- 2016
17. Strength of concrete structures under dynamic loading
- Author
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Z. R. Galyautdinov, O. G. Kumpyak, and D. N. Kokorin
- Subjects
Materials science ,Computer program ,Consolidation (soil) ,Dynamic loading ,business.industry ,Oblique case ,Structural engineering ,business ,Research findings ,Finite element method - Abstract
The use of elastic supports is one the efficient methods of decreasing the dynamic loading. The paper describes the influence of elastic supports on the stress-strain state of steel concrete structures exposed to one-time dynamic loading resulting in failure. Oblique bending beams on elastic supports and their elastic, elastoplastic, and elastoplastic consolidation behavior are considered in this paper. For numerical calculations the developed computer program is used based on the finite element method. Research findings prove high efficiency of elastic supports under dynamic loading conditions. The most effective behavior of elastic supports is demonstrated at the elastoplastic stage. A good agreement is observed between the theoretical and experimental results.
- Published
- 2016
18. Service contract with periodic preventive maintenance for a dump truck sold with a two-dimensional warranty
- Author
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Hennie Husniah, Akbar Nasrum, and Udjianna S. Pasaribu
- Subjects
Truck ,Corrective maintenance ,Planned maintenance ,Warranty ,Operations management ,Business ,Original equipment manufacturer ,Preventive maintenance ,Profit (economics) ,Contract price - Abstract
This paper deals with maintenance service contract for a dump truck sold with a two-dimensional warranties. We consider a situation where an agent offers two maintenance contract options and the owner of the equipment has to select the optimal option either the OEM carried out all repairs and preventive maintenance activities (option one) or the OEM only carries out failure while the costumer undertakes preventive maintenance action in-house (option two). As the number of preventive maintenance and corrective maintenance that occurs in the area of servicing contracts is very influential in determining the value of the contract, we have to determine the optimal time between preventive maintenance that can minimize the cost of repair in the contract area. Moreover, we also study the maintenance service contract considering reduction of the intensity function after preventive maintenance from both the owner and OEM point of views. In this paper, we use a Weibull intensity function to consider a product with increasing failure intensity. We use a non-cooperative game formulation to determine the optimal price structure (i.e., the contract price and repair cost) for the OEM and the owner. A numerical example derived from the model has shown that if the owner choose option one then the owner obtain a higher profit compared with the profit resulted from option two. The result agree with earlier work which uses the accelerated failure time (AFT) for the failure modeling, while here we model the failure of the dump truck without the use of the AFT.
- Published
- 2016
19. Influence of carbon fillers nature on the structural and morphological properties of polyurethane-based composites
- Author
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S. V. Pavlov, S. V. Melentyev, and T. D. Malinovskaya
- Subjects
Resistive touchscreen ,Materials science ,Mixing (process engineering) ,chemistry.chemical_element ,engineering.material ,chemistry.chemical_compound ,chemistry ,Electrical resistivity and conductivity ,Filler (materials) ,engineering ,Graphite ,Composite material ,Electrical conductor ,Carbon ,Polyurethane - Abstract
The present paper is devoted to studying structural and morphological properties of the resistive composite materials based on the polyurethane binder. The paper shows the influence of nature, size, shape, concentration of conductive carbon fillers (channel black K-163, graphite element GE-3, colloidal-graphite preparation C-1) and the method of their introduction into the binder to form the electrical conductivity of composites. Experimentally it was found out that a homogeneous composite structure reaches dispersive mixing filler and binder within 120 min. The analysis of the morphological pattern surfaces and chipping resistance materials has demonstrated that composites with colloidal-graphite preparation C-1 are more unimodal with the same concentrations of the investigated fillers.
- Published
- 2016
20. Advanced reliability methods – A review
- Author
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David S. Forsyth
- Subjects
Engineering ,Empirical research ,business.industry ,Nondestructive testing ,Bayesian probability ,Scalar (physics) ,Metric (unit) ,Structural health monitoring ,business ,Risk assessment ,Statistical power ,Reliability engineering - Abstract
There are a number of challenges to the current practices for Probability of Detection (POD) assessment. Some Nondestructive Testing (NDT) methods, especially those that are image-based, may not provide a simple relationship between a scalar NDT response and a damage size. Some damage types are not easily characterized by a single scalar metric. Other sensing paradigms, such as structural health monitoring, could theoretically replace NDT but require a POD estimate. And the cost of performing large empirical studies to estimate POD can be prohibitive. The response of the research community has been to develop new methods that can be used to generate the same information, POD, in a form that can be used by engineering designers. This paper will highlight approaches to image-based data and complex defects, Model Assisted POD estimation, and Bayesian methods for combining information. This paper will also review the relationship of the POD estimate, confidence bounds, tolerance bounds, and risk assessment.
- Published
- 2016
21. 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
22. Mathematical analysis of intermittent gas injection model in oil production
- Author
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S. Edy, M. Leksono, Tasmi, D. R. Silvya, and S. Pudjo
- Subjects
Chromatography ,Chemistry ,Ordinary differential equation ,Oil production ,Gas lift ,Separator (oil production) ,Momentum conservation ,Choke ,Wet gas ,Mechanics ,Astrophysics::Galaxy Astrophysics - Abstract
Intermittent gas injection is a method to help oil production process. Gas is injected through choke in surface and then gas into tubing. Gas forms three areas in tubing: gas column area, film area and slug area. Gas column is used to propel slug area until surface. A mathematical model of intermittent gas injection is developed in gas column area, film area and slug area. Model is expanding based on mass and momentum conservation. Using assume film thickness constant in tubing, model has been developed by Tasmi et. al. [14]. Model consists of 10 ordinary differential equations. In this paper, assumption of pressure in gas column is uniform. Model consist of 9 ordinary differential equations. Connection of several variables can be obtained from this model. Therefore, dynamics of all variables that affect to intermittent gas lift process can be seen from four equations. To study the behavior of variables can be analyzed numerically and mathematically. In this paper, simple mathematically analysis approach is used to study behavior of the variables. Variables that affect to intermittent gas injection are pressure in upstream valve and in gas column. Pressure in upstream valve will decrease when gas mass in valve greater than gas mass in choke. Dynamic of the pressure in the gas column will decrease and increase depending on pressure in upstream valve.
- Published
- 2016
23. Formation and sustainment of field reversed configuration (FRC) plasmas by spheromak merging and neutral beam injection
- Author
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Masaaki Yamada
- Subjects
Physics ,Spheromak ,business.industry ,Compact toroid ,Plasma shaping ,Electrical engineering ,Field-reversed configuration ,Magnetic reconnection ,Plasma ,Magnetohydrodynamics ,business ,Neutral beam injection ,Computational physics - Abstract
This paper briefly reviews a compact toroid reactor concept that addresses critical issues for forming, stabilizing and sustaining a field reversed configuration (FRC) with the use of plasma merging, plasma shaping, conducting shells, neutral beam injection (NBI). In this concept, an FRC plasma is generated by the merging of counter-helicity spheromaks produced by inductive discharges and sustained by the use of neutral beam injection (NBI). Plasma shaping, conducting shells, and the NBI would provide stabilization to global MHD modes. Although a specific FRC reactor design is outside the scope of the present paper, an example of a promising FRC reactor program is summarized based on the previously developed SPIRIT (Self-organized Plasmas by Induction, Reconnection and Injection Techniques) concept in order to connect this concept to the recently achieved the High Performance FRC plasmas obtained by Tri Alpha Energy [Binderbauer et al, Phys. Plasmas 22,056110, (2015)]. This paper includes a brief summary of the previous concept paper by M. Yamada et al, Plasma Fusion Res. 2, 004 (2007) and the recent experimental results from MRX.
- Published
- 2016
24. Challenges of NDE simulation tool validation, optimization, and utilization for composites
- Author
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Peter D. Juarez, Cara A. C. Leckey, and Jeffrey P. Seebo
- Subjects
Modeling and simulation ,Engineering ,Guided wave testing ,business.industry ,Aerospace materials ,Nondestructive testing ,Verification and validation of computer simulation models ,Structural health monitoring ,Composite material ,business ,Aerospace ,Research center - Abstract
Rapid, realistic nondestructive evaluation (NDE) simulation tools can aid in inspection optimization and prediction of inspectability for advanced aerospace materials and designs. NDE simulation tools may someday aid in the design and certification of aerospace components; potentially shortening the time from material development to implementation by industry and government. Furthermore, ultrasound modeling and simulation are expected to play a significant future role in validating the capabilities and limitations of guided wave based structural health monitoring (SHM) systems. The current state-of-the-art in ultrasonic NDE/SHM simulation is still far from the goal of rapidly simulating damage detection techniques for large scale, complex geometry composite components/vehicles containing realistic damage types. Ongoing work at NASA Langley Research Center is focused on advanced ultrasonic simulation tool development. This paper discusses challenges of simulation tool validation, optimization, and utilization for composites. Ongoing simulation tool development work is described along with examples of simulation validation and optimization challenges that are more broadly applicable to all NDE simulation tools. The paper will also discuss examples of simulation tool utilization at NASA to develop new damage characterization methods for composites, and associated challenges in experimentally validating those methods.
- Published
- 2016
25. 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
26. Multidimensional guided wave dispersion recovery for locating defects in composite materials
- Author
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Joel B. Harley, Luca De Marchi, Harley, Joel B, and De Marchi, Luca
- Subjects
Structural health monitoring ,Materials science ,Guided wave testing ,business.industry ,Acoustics ,Attenuation ,Isotropy ,Triangulation (social science) ,Inverse problem ,Optics ,Dispersion (water waves) ,business ,Anisotropy - Abstract
This paper provides a framework for characterizing anisotropic guided waves to locate damage in composite structures. Composite guided wave structural health monitoring is a significant challenge due to anisotropy. Wave velocities and attenuation vary as a function of propagation direction. Traditional localization algorithms, such as triangulation and delay-and-sum beamforming, fail for composite monitoring because they rely on isotropic velocity assumptions. Estimating the anisotropic velocities is also challenging because the inverse problem is inherently ill-posed. We cannot solve for an infinite number of directions with a finite number of measurements. This paper addresses these challenges by deriving a physics-based model for unidirectional anisotropy and integrating it with sparse recovery tools and matched field processing to characterize composite guided waves and locate an acoustic source. We validate our approach with experimental laser doppler vibrometry measurements from a glass fiber reinforced composite panel. We achieve localization accuracies of more than 290 and 49 times better, respectively, than delay-and-sum and matched field processing with isotropic assumptions.
- Published
- 2016
27. Palm oil industry: A review of the literature on the modelling approaches and potential solution
- Author
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Norhaslinda Zainal Abidin and M. Faeid M. Zabid
- Subjects
Engineering ,Risk analysis (engineering) ,Management science ,Process (engineering) ,business.industry ,Genetic algorithm ,Policy maker ,Palm oil ,Developing country ,Context (language use) ,Policy design ,business ,System dynamics - Abstract
Palm oil industry plays an important role as a backbone to the economy of a country, especially in many developing countries. Various issues related to the palm oil context have been studied rigorously by previous researchers using appropriate modeling approaches. Thus, the purpose of this paper is to present an overview of existing modeling approaches used by researchers in studying several issues in the palm oil industry. However, there are still limited numbers of researches that focus to determine the impact of strategy policies on palm oil studies. Furthermore, this paper introduces an improved system dynamics and genetic algorithm technique to facilitate the policy design process in palm oil industry. The proposed method is expected to become a framework for structured policy design process to assist the policy maker in evaluating and designing appropriate policies.
- Published
- 2015
28. Measuring successful knowledge sharing among academia through social media
- Author
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Nerda Zura Zabidi, Rose Alinda Alias, Nor Intan Saniah Sulaiman, Mohd Faizal Omar, and S.B. Ghazali
- Subjects
Positive shift ,Engineering ,Identification (information) ,Knowledge management ,Work (electrical) ,Public use ,business.industry ,Theory of planned behavior ,Social media ,Public relations ,business ,Fuzzy logic ,Knowledge sharing - Abstract
This paper aims to study the influence of social media on knowledge sharing among academia. Previously, many researches have been done to explore the importance emergence of social media for public use, but there are still limited studies on how this technological advancement affects the academia. For this study, Facebook is chosen as one of the online social networking tools as the medium of knowledge sharing. To begin with, this study is started with the identification of factors that encourage the academia to share their knowledge through social media. These factors are then categorized based on Theory of Planned Behavior (TPB). After this knowledge has successfully shared, the level of successful knowledge sharing through Facebook is modeled using Fuzzy Logic. Fuzzy inputs for this study are the number of like, comment and share. Findings from this study indeed showed that there are many reasons encouraging academia to utilize social media for their work. Besides, this paper contributes new knowledge to fuzzy logic application as it is the first known research in measuring Facebook engagement for knowledge sharing purposes. In conclusion although there exist some barriers and limitations with the use of social media, academia are showing a positive shift in the application of these tools for work.
- Published
- 2015
29. Solving nonlinear system of third-order boundary value problems using block method
- Author
-
Zanariah Abdul Majid, Khairil Iskandar Othman, Fudziah Ismail, Mohamed Suleiman, and Phang Pei See
- Subjects
Nonlinear system ,Mathematical optimization ,Shooting method ,Iterative method ,Initial value problem ,Applied mathematics ,Boundary value problem ,Boundary knot method ,Singular boundary method ,Mathematics ,Variable (mathematics) - Abstract
In this paper, we propose an algorithm of two-point block method to solve the nonlinear system of third-order boundary value problems directly. The proposed method is presented in a simple form of Adams type and two approximate solutions will be obtained simultaneously with the block method using variable step size strategy. The method will be implemented with the multiple shooting technique via the three-step iterative method to generate the missing initial value. Most of the existence method will reduce the third-order boundary value problems to a system of first order equations where the systems of six equations need to be solved. The method we proposed in this paper will solve the third-order boundary value problems directly. Two numerical examples are given to illustrate the efficiency of the proposed method.
- Published
- 2015
30. Combining multivariate Markov chains
- Author
-
Jesús E. García
- Subjects
Combinatorics ,symbols.namesake ,Markov chain mixing time ,Markov chain ,Markov renewal process ,Variable-order Markov model ,symbols ,Applied mathematics ,Markov process ,Additive Markov chain ,Markov property ,Markov model ,Mathematics - Abstract
In this paper we address the problem of modelling multivariate finite order Markov chains, when the dataset is not large enough to apply the usual methodology. The number of parameters needed for a multivariate Markov chain grows exponentially with the process order and dimension of the chain’s alphabet. Usually, when the data set is small, the order of the fitted model is reduced compared to the true process order. In this paper we introduce a strategy to estimate a multivariate process, through this new strategy the estimated order will be greater than the order achieved using standard statistical procedures. We apply the partition Markov models, which is a family of models, where each member is identified by a partition of the state space. The procedure consist in obtaining a partition of the state space that is constructed from a combination of the partitions corresponding to the marginal processes of the multivariate chain, and the partition corresponding to the multivariate Markov chain.
- Published
- 2015
31. Everything under the Sun: A review of solar neutrinos
- Author
-
Gabriel D. Orebi Gann
- Subjects
Physics ,Particle physics ,Solar System ,Physics::Instrumentation and Detectors ,010308 nuclear & particles physics ,Physics beyond the Standard Model ,Solar neutrino ,Astronomy ,01 natural sciences ,7. Clean energy ,Neutrino detector ,Physics::Space Physics ,0103 physical sciences ,High Energy Physics::Experiment ,Formation and evolution of the Solar System ,Neutrino ,010306 general physics ,Neutrino oscillation ,Borexino - Abstract
Solar neutrinos offer a unique opportunity to study the interaction of neutrinos with matter, a sensitive search for potential new physics effects, and a probe of solar structure and solar system formation. This paper describes the broad physics program addressed by solar neutrino studies, presents the current suite of experiments programs, and describes several potential future detectors that could address the open questions in this field. This paper is a summary of a talk presented at the Neutrino 2014 conference in Boston.
- Published
- 2015
32. FlightGear application for flight simulation of a mini-UAV
- Author
-
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
33. CERN and 60 years of science for peace
- Author
-
Rolf-Dieter Heuer
- Subjects
Engineering ,Presentation ,Large Hadron Collider ,business.industry ,Interface (Java) ,media_common.quotation_subject ,Systems engineering ,business ,Engineering physics ,media_common - Abstract
This paper presents CERN as it celebrates its 60th Anniversary since its founding. The presentation first discusses the mission of CERN and its role as an inter-governmental Organization. The paper also reviews aspects of the particle physics research programme, looking at both current and future accelerator-based facilities at the high-energy and intensity frontiers. Finally, the paper considers issues beyond fundamental research, such as capacity-building and the interface between Art and Science.
- Published
- 2015
34. nuSTORM: Neutrinos from STORed Muons
- Author
-
A. D. Bross
- Subjects
Physics ,Particle physics ,Muon ,Physics::Instrumentation and Detectors ,Physics beyond the Standard Model ,Solar neutrino ,Detector ,Flux ,Solar neutrino problem ,Nuclear physics ,MiniBooNE ,Particle decay ,High Energy Physics::Experiment ,Anomaly (physics) ,Neutrino ,Neutrino oscillation - Abstract
The results of LSND and MiniBooNE, along with the recent papers on a possible reactor neutrino flux anomaly, give tantalizing hints of new physics. Models beyond the νSM have been developed to explain these results and involve one or more additional neutrinos that are non-interacting or “sterile.” Neutrino beams produced from the decay of muons in a racetrack-like decay ring provide a powerful way to study this potential new physics. In this paper, I will describe the facility, nuSTORM, and an appropriate far detector for neutrino oscillation searches at short baseline. I will present sensitivity plots that indicated that this experimental approach can provide well over 5 σ confirmation or rejection of the LSND/MinBooNE results.
- Published
- 2015
35. Quasi-Rayleigh waves in butt-welded thick steel plate
- Author
-
Tuncay Kamas, Bin Lin, and Victor Giurgiutiu
- Subjects
Materials science ,business.industry ,Acoustics ,Butt welding ,Isotropy ,Structural engineering ,Acoustic wave ,Resonator ,symbols.namesake ,Lamb waves ,symbols ,Ultrasonic sensor ,Phase velocity ,Rayleigh wave ,business - Abstract
This paper discusses theoretical and experimental analyses of weld guided surface acoustic waves (SAW) through the guided wave propagation (GWP) analyses. The GWP analyses have been carried out by utilizing piezoelectric wafer active sensors (PWAS) for in situ structural inspection of a thick steel plate with butt weld as the weld bead is ground flush. Ultrasonic techniques are commonly used for validation of welded structures in many in-situ monitoring applications, e.g. in off-shore structures, in nuclear and pressure vessel industries and in a range of naval applications. PWAS is recently employed in such ultrasonic applications as a resonator as well as a transducer. Quasi-Rayleigh waves a.k.a. SAW can be generated in relatively thick isotropic elastic plate having the same phase velocity as Rayleigh waves whereas Rayleigh waves are a high frequency approximation of the first symmetric (S0) and anti-symmetric (A0) Lamb wave modes. As the frequency becomes very high the S0 and the A0 wave speeds coalesce, and both have the same value. This value is exactly the Rayleigh wave speed and becomes constant along the frequency i.e. Rayleigh waves are non-dispersive guided surface acoustic waves. The study is followed with weld-GWP tests through the pitch-catch method along the butt weld line. The tuning curves of quasi-Rayleigh wave are determined to show the tuning and trapping effect of the weld bead that has higher thickness than the adjacent plates on producing a dominant quasi-Rayleigh wave mode. The significant usage of the weld tuned and guided quasi-Rayleigh wave mode is essentially discussed for the applications in the in-situ inspection of relatively thick structures with butt weld such as naval offshore structures. The paper ends with summary, conclusions and suggestions for future work.
- Published
- 2015
36. Benchmark of numerical tools simulating beam propagation and secondary particles in ITER NBI
- Author
-
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
37. Ultrasonic vibrothermography using low-power actuators: An impact damage detection case study
- Author
-
F. Passilly, D. Balageas, Jean-Michel Roche, B. Lamboul, ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), Transferts, écoulements, fluides, énergétique (TREFLE), and Université Sciences et Technologies - Bordeaux 1-École Nationale Supérieure de Chimie et de Physique de Bordeaux (ENSCPB)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Materials science ,Acoustics ,Phase (waves) ,GUIDED WAVES ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Piezoelectricity ,Signal ,[SPI.MAT]Engineering Sciences [physics]/Materials ,Amplitude ,VIBROTHERMOGRAPHY ,0103 physical sciences ,ULTRASONICS ,LOCK-IN DETECTION ,Ultrasonic sensor ,0210 nano-technology ,Actuator ,010301 acoustics ,Frequency modulation ,Excitation - Abstract
International audience; This paper investigates the use of low-power piezoelectric discs for the detection of an impact damage in a composite carbon-fibre plate using ultrasonic vibrothermography. The frequency of excitation is set in a range from tens to a few hundred kHz to generate guided waves in the plate. A carrier modulation signal (typically 0.1 Hz) is applied to the input excitation signal to perform lock-in detection on the surface temperature signals collected by a middle-wave infrared camera. The paper studies the influence of excitation parameters (excitation frequency, modulation frequency, amplitude) on the defect response. Finally, the paper highlights some trade-offs for the detection of the considered impact damage case, based on the obtained lock-in phase and amplitude maps.
- Published
- 2015
38. Differences between ITIL® v2 and ITIL® v3 with respect to service transition and service operation
- Author
-
Roman Jasek, Alena Kolčavová, Lukas Kralik, and Roman Žák
- Subjects
Life Cycle ,Service (business) ,Service strategy ,Engineering ,Knowledge management ,Process management ,ITIL ,business.industry ,Service design ,Service transition ,Service Management ,Information Technology Infrastructure Library ,Work (electrical) ,Service Operation ,Information technology management ,Key (cryptography) ,Changes in ITIL ,business - Abstract
This paper follows the article: Differences Between ITIL (R) V2 and ITIL (R) V3 with Respect to Service Strategy and Service Design. The main aim is to summarize the changes that relate to key publications, Service Transition and Service Operation. In conclusion, areevaluated the objectives of the current version of ITIL (R) v3 and the unofficial benefits. The purpose of these papers is to provide the necessary overview of the current situation in the field of IT management to facilitate and streamline the work of IT managers.
- Published
- 2015
39. A logic for robotics?
- Author
-
Luís Soares Barbosa, Alexandre Madeira, Manuel A. Martins, Renato Neves, and Universidade do Minho
- Subjects
Logic in computer science ,Science & Technology ,business.industry ,Computer science ,Computational logic ,Multimodal logic ,020207 software engineering ,Robotics ,0102 computer and information sciences ,02 engineering and technology ,01 natural sciences ,Dynamic logic ,TheoryofComputation_MATHEMATICALLOGICANDFORMALLANGUAGES ,Description logic ,Philosophy of logic ,010201 computation theory & mathematics ,TheoryofComputation_LOGICSANDMEANINGSOFPROGRAMS ,Computer Science::Logic in Computer Science ,0202 electrical engineering, electronic engineering, information engineering ,Dynamic logic (modal logic) ,Artificial intelligence ,business ,Temporal logic of actions ,Autoepistemic logic ,Logic optimization - Abstract
This paper introduces HHL, a hierarchical variant of hybrid logic. First-order correspondence and a Hennessy-Milner like theorem relating (hierarchical) bisimulation and logical equivalence for HHLare presented. Combining hierarchical transition structures with the ability to refer to specific states at any level of description, this logic seems suitable to express and verify properties of hierarchical transition systems, a pervasive semantic structure in Computer Science., Dynamic logic combines logic with programs, which at a certain level of abstraction, can be regarded as behaviours changing the system state and, therefore, the truth value of formulas. This paper suggests a method for generating such logics for the domain of robot controllers and illustrates it with a logic for handling resource consumption.
- Published
- 2015
40. Small modular reactor (SMR) development plan in Korea
- Author
-
Il Soon Hwang, Yong-Hoon Shin, Sangrok Park, Swongho Choi, and Byong Sup Kim
- Subjects
Engineering ,Development plan ,Conceptual design ,Waste management ,Standardization ,business.industry ,Software deployment ,Systems engineering ,Electricity ,Nuclear power ,Modular design ,business ,Small modular reactor - Abstract
Since the first nuclear power was engaged in Korean electricity grid in 1978, intensive research and development has been focused on localization and standardization of large pressurized water reactors (PWRs) aiming at providing Korean peninsula and beyond with economical and safe power source. With increased priority placed on the safety since Chernobyl accident, Korean nuclear power R&D activity has been diversified into advanced PWR, small modular PWR and generation IV reactors. After the outbreak of Fukushima accident, inherently safe small modular reactor (SMR) receives growing interest in Korea and Europe. In this paper, we will describe recent status of evolving designs of SMR, their advantages and challenges. In particular, the conceptual design of lead-bismuth cooled SMR in Korea, URANUS with 40∼70 MWe is examined in detail. This paper will cover a framework of the program and a strategy for the successful deployment of small modular reactor how the goals would entail and the approach to collaboration with other entities.
- Published
- 2015
41. Economics of online structural health monitoring of wind turbines: Cost benefit analysis
- Author
-
Leonard J. Bond and Jeremy Van Dam
- Subjects
Engineering ,Downtime ,Wind power ,Corrective maintenance ,Cost–benefit analysis ,business.industry ,business ,Cost of electricity by source ,Investment (macroeconomics) ,Turbine ,Preventive maintenance ,Reliability engineering - Abstract
Operations and maintenance (O&M) costs have an average share over the lifetime of the turbine of approximately 20%-25% of the total levelized cost per kWh of electricity produced. Online structural health monitoring (OSHM) and condition-based maintenance (CBM) of wind turbine blades has the potential to reduce O&M costs and hence reduce the overall cost of wind energy. OSHM and CBM offer the potential to improve turbine blade life cycle management, limit the number of physical inspections, and reduce the potential for missed significant defects. An OSHM system would reduce the need for physical inspections, and have inspections occur only after problem detection takes place. In the economics of wind energy, failures and unplanned outages can cause significant downtime, particularly while waiting for the manufacturing and shipping of major parts. This paper will report a review and assessment of SHM technologies and a cost benefit analysis, which will examine whether the added costs associated with an OSHM system will give an adequate return on the investment. One method in which OSHM reduces costs is, in part, by converting corrective maintenance to preventative maintenance. This paper shows that under both best and worse conditions implementing an OSHM system is cost effective in more than 50% of the trials, which have been performed. Opportunities appear to exist to improve the economic justification for implementing OSHM.
- Published
- 2015
42. The efficiency of convergence rate for IMSS2-5D procedure
- Author
-
Noraini Jamaludin, Nur Izzati Rashid, Nooraini Zainuddin, Mansor Monsi, and Nasruddin Hassan
- Subjects
Mathematical optimization ,Polynomial ,Rate of convergence ,Simple (abstract algebra) ,Bounding overwatch ,Interval (mathematics) ,Midpoint ,Mathematics - Abstract
A new iterative procedure is formulated in this paper known as the interval midpoint symmetric single-step IMSS2-5D procedure. In this paper, we consider this new procedure in order to describe the rate of convergence of the IMSS2-5D procedure. It is analytically proven that the IMSS2-5D procedure has a higher convergence rate than ISS2 and ISS2-5D, verifying the rate of convergence to be at least 12. Hence, computational time is reduced since this procedure is more efficient for bounding simple zeros simultaneously. Hence, it would be effective to use this procedure in determining the zeros of polynomial simultaneously.
- Published
- 2015
43. On the design of distributed air quality monitoring systems
- Author
-
Alejandro David Velasco, Renato Ferrero, Bartolomeo Montrucchio, Maurizio Rebaudengo, and Filippo Gandino
- Subjects
Engineering ,business.industry ,computer.software_genre ,pervasive monitoring ,Air quality monitoring ,Key point ,wireless sensor network ,Air pollutants ,Systems engineering ,air pollutants ,Data mining ,business ,Air quality index ,Wireless sensor network ,computer - Abstract
Nowadays, the air quality is considered a key point, and its monitoring is not only suggested but it is even required in many countries. Since traditional standard monitors for air quality are very expensive, the use of a low-cost distributed network of sensors represents a valid complementary approach. This paper discusses the benefits of a distributed approach and analyzes the main elements that should be taken into account during the design of a distributed system for the air quality monitoring. This paper aims at representing a valuable aid for researchers and practitioners interested in the topic.
- Published
- 2015
44. Thermo-mechanical simulation of liquid-supported stretch blow molding
- Author
-
Markus Stommel and Johannes Zimmer
- Subjects
Blow molding ,Differential scanning calorimetry ,Materials science ,Heat transfer ,Formability ,Forming processes ,Process variable ,Molding (process) ,Deformation (meteorology) ,Composite material - Abstract
Stretch blow molding is the well-established plastics forming method to produce Polyehtylene therephtalate (PET) bottles. An injection molded preform is heated up above the PET glass transition temperature (Tg∼85°C) and subsequently inflated by pressurized air into a closed cavity. In the follow-up filling process, the resulting bottle is filled with the final product. A recently developed modification of the process combines the blowing and filling stages by directly using the final liquid product to inflate the preform. In a previously published paper, a mechanical simulation and successful evaluation of this liquid-driven stretch blow molding process was presented. In this way, a realistic process parameter dependent simulation of the preform deformation throughout the forming process was enabled, whereas the preform temperature evolution during forming was neglected. However, the formability of the preform is highly reduced when the temperature sinks below Tg during forming. Experimental investigations show temperature-induced failure cases due to the fast heat transfer between hot preform and cold liquid. Therefore, in this paper, a process dependent simulation of the temperature evolution during processing to avoid preform failure is presented. For this purpose, the previously developed mechanical model is used to extract the time dependent thickness evolution. This information serves as input for the heat transfer simulation. The required material parameters are calibrated from preform cooling experiments recorded with an infrared-camera. Furthermore, the high deformation ratios during processing lead to strain induced crystallization. This exothermal reaction is included into the simulation by extracting data from preform measurements at different stages of deformation via Differential Scanning Calorimetry (DSC). Finally, the thermal simulation model is evaluated by free forming experiments, recorded by a high-speed infrared camera.
- Published
- 2015
45. JSBSim library for flight dynamics modelling of a mini-UAV
- Author
-
Tomáš Vogeltanz and Roman Jasek
- Subjects
Aircraft flight mechanics ,Engineering ,business.product_category ,business.industry ,UAV ,JSBSim ,flight dynamics model ,simulation ,airplane ,Airplane ,modelling ,Aeronautics ,Flight dynamics ,Section (archaeology) ,Aerospace engineering ,business ,aircraft - Abstract
This paper presents using of JSBSim library for flight dynamics modelling 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, forces, moments, and the main components of typical aircraft. The main section briefly describes a flight dynamics model and summarizes the information about JSBSim library. Then, a way of using the library for the modelling of a mini-UAV is shown. A basic script for lifting and stabilization of the UAV has been developed and described. Finally, the results of JSBSim test are discussed.
- Published
- 2015
46. Adaptive sliding mode control for a class of chaotic systems
- Author
-
B. Zalam, R. Farid, and A. Ibrahim
- Subjects
Nonlinear Sciences::Chaotic Dynamics ,Lyapunov stability ,Nonlinear system ,Control theory ,Synchronization of chaos ,Mode (statistics) ,Stability (learning theory) ,Sliding mode control ,Chaos theory ,Mathematics - Abstract
Chaos control here means to design a controller that is able to mitigating or eliminating the chaos behavior of nonlinear systems that experiencing such phenomenon. In this paper, an Adaptive Sliding Mode Controller (ASMC) is presented based on Lyapunov stability theory. The well known Chua's circuit is chosen to be our case study in this paper. The study shows the effectiveness of the proposed adaptive sliding mode controller.
- Published
- 2015
47. Die drool and polymer degradation
- Author
-
P. H. Gilbert, A. Jeffrey Giacomin, and Geoffrey Stephen Hoy
- Subjects
chemistry.chemical_classification ,Materials science ,Polymers and Plastics ,Degradation kinetics ,General Chemical Engineering ,Materials Science (miscellaneous) ,Operational Problem ,Stress induced ,Plastics extrusion ,02 engineering and technology ,Slip (materials science) ,Die swell ,Polymer ,021001 nanoscience & nanotechnology ,Polymer degradation ,020401 chemical engineering ,chemistry ,Materials Chemistry ,0204 chemical engineering ,Composite material ,0210 nano-technology - Abstract
Die drool is an operational problem associated with polymer extrusion. Extrudate collects outside of the die, necessitating periodic disruptions for cleaning. There exists some debate as to the mechanism that produces die drool: stress induced fractionation or thermal degradation. This paper examines the latter. In cohesive failure, a slip discontinuity develops in the velocity profile, where heat is generated by friction. This slip heating can contribute to resin degradation, resulting in lower molecular weight fragments in the die drool. This paper examines the kinetics of this degradation, its influence on die drool rates, and on the resulting polymer concentration profiles in the drool layer and in the bulk.
- Published
- 2015
48. Microworlds of the dynamic balanced scorecard for university (DBSC-UNI)
- Author
-
Nurul Nazihah Hawari and Razman Mat Tahar
- Subjects
Strategic planning ,Engineering ,Balanced scorecard ,Higher education ,business.industry ,Management science ,Seven Management and Planning Tools ,media_common.quotation_subject ,System dynamics ,MicroWorlds ,Performance measurement ,Quality (business) ,business ,computer ,media_common ,computer.programming_language - Abstract
This research focuses on the development of a Microworlds of the dynamic balanced scorecard for university in order to enhance the university strategic planning process. To develop the model, we integrated both the balanced scorecard method and the system dynamics modelling method. Contrasting the traditional university planning tools, the developed model addresses university management problems holistically and dynamically. It is found that using system dynamics modelling method, the cause-and-effect relationships among variables related to the four conventional balanced scorecard perspectives are better understand. The dynamic processes that give rise to performance differences between targeted and actual performances also could be better understood. So, it is expected that the quality of the decisions taken are improved because of being better informed. The developed Microworlds can be exploited by university management to design policies that can positively influence the future in the direction of desired goals, and will have minimal side effects. This paper integrates balanced scorecard and system dynamics modelling methods in analyzing university performance. Therefore, this paper demonstrates the effectiveness and strength of system dynamics modelling method in solving problem in strategic planning area particularly in higher education sector.
- Published
- 2015
49. Maximizing vector distances using differential evolution—Relation to data redundancy
- Author
-
Roman Jasek, Martin Kolarik, and Zuzana Kominkova Oplatkova
- Subjects
Set (abstract data type) ,Mathematical optimization ,Relation (database) ,Data redundancy ,Differential evolution ,Mathematics - Abstract
This paper studies how redundant data affect maximizing of weighted distances of vectors in a set of vectors. To maximize distances differential evolution is used, because the problem does not have analytical solution and is complex. This paper at first describes suppressing of redundant data mathematically and then it checks this theoretical result in two experiments practically. As a result it was found that both experiments are in correspondence with theory.
- Published
- 2015
50. Excitability of guided waves in composites with PWAS transducers
- Author
-
Victor Giurgiutiu and Yanfeng Shen
- Subjects
Engineering ,Lamb waves ,Guided wave testing ,business.industry ,Nondestructive testing ,Frequency domain ,Ultrasonic sensor ,Structural health monitoring ,Composite material ,business ,Dispersion (water waves) ,Finite element method - Abstract
Piezoelectric Wafer Active Sensors (PWAS) are convenient enablers for generating and receiving ultrasonic guided waves. The wide application of composite structures has put new challenges for the Structural Health Monitoring (SHM) and Nondestructive Evaluation (NDE) community due to the general anisotropic behaviors and complicated guided wave features in composites. The excitability of guided waves in composite structures directly influences the implementation of active sensing systems to achieve the best interrogation of certain sensing directions. This paper presents a hybrid modeling technique for studying the excitably of guided waves in composite structures with PWAS transducers. This hybrid technique comprehensively covers local finite element model (FEM), semi-analytical finite element (SAFE) method, and analytical guided wave solutions. Harmonic analysis of a small-size local FEM with non-reflective boundaries (NRB) was carried out for obtaining guided wave generation features in plate structures. The PWAS transducers were modeled with coupled filed elements. Thus, the FEM can fully capture the geometry and material property effects of PWAS transducers and their influence on the guided wave excitation. SAFE method was used to obtain the complicated guided wave features in composites such as dispersion curves and modeshapes. The SAFE procedure was coded into MATLAB Graphical User Interface (GUI), and the software SAFE-DISPERSION was developed. To study the excitability of each wave mode, we considered all the possible wave modes being generated simultaneously and propagating independently. The analytical wave expressions based on the exact guided wave solution with Hankel functions were used to join the SAFE method and the local FEM. Formulated in frequency domain, the hybrid model is highly efficient, providing an over determined equation system for the calculation of mode participation factors. Case studies were carried out: (1) the Lamb wave excitability in an aluminum plate was investigated and compared with classical pin force models to show the feasibility of the hybrid technique; (2) the guided wave excitability in a woven glass fiber composite (GFRP) plate was studied with circular and square PWAS transducers. The paper finishes with summary, conclusions, and suggestions for future work.
- Published
- 2015
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