Granulometric analysis of sediments containing transuranic radionuclides

International Nuclear Information System (INIS)

Smith, R.M.; Additon, M.K.

1980-11-01

A dry sieving technique using a sonic sifter was selected for the granulometric analysis of sediment samples containing radionuclide contamination. A sieve facility was established in the 234-5Z building for this purpose. Fifty-two contaminated sediment samples from the 216-Z-1A crib were sieved in the facility at a rate of two to four samples per day with no major problems. A comparison of particle size and radionuclide concentration indicated that there is no obvious benefit to particle size separation as a means of sediment decontamination, though an economic analysis will have to be conducted before a final decision can be made

Occupational exposure to lead--granulometric distribution of airborne lead in relation to risk assessment.

Science.gov (United States)

Carelli, G; Masci, O; Altieri, A; Castellino, N

1999-07-01

The amount of airborne lead absorbed by the body during occupational exposure depends not only on lead concentration in workplace air, but also on the granulometric distribution of the aerosol. The Occupational Safety and Health Administration (OSHA) set the lead Permissible Exposure Limit (PEL) at 50 micrograms/m3 on the basis of Bernard's model and a number of assumptions, including assumption "C", which predicts that the first 12.5 micrograms/m3 are made up of fine particles (aerodynamic diameter 1 micron. Occupational exposure to airborne lead at a concentration of 50 micrograms/m3 and a granulometric distribution calculated according to the above mentioned assumption, leads, in the model, to a mean blood level of 40 micrograms/dl. In the present study, we tested the validity of assumption "C" in the environmental air of a factory that manufactured crystal glassware containing 24% lead oxide. An 8-stage impactor was used to measure the particle size of airborne dust collected from personal and area samplings. Results indicate that, on the whole, assumption "C" cannot be considered valid in the work environment investigated in this study. As a result, lead absorption levels in exposed workers may be noticeably different from those predicted by the OSHA model. We therefore suggest that in order to make a correct evaluation of the risk of occupational exposure to lead, it is essential to integrate total airborne lead concentration with a measurement of the granulometric distribution of the aerosol.

Automatic morphometry of synaptic boutons of cultured cells using granulometric analysis of digital images

NARCIS (Netherlands)

Prodanov, D.P.; Heeroma, Joost; Marani, Enrico

2006-01-01

Numbers, linear density, and surface area of synaptic boutons can be important parameters in studies on synaptic plasticity in cultured neurons. We present a method for automatic identification and morphometry of boutons based on filtering of digital images using granulometric analysis. Cultures of

Bottom Sediment Granulometric Data for the Continental Margins of the Bering, Chukchi, East Siberia, Laptev, and Beaufort Seas

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — These data are part of Roberts, Richard W., University of Washington, Department of Oceanography Special Report No. 70, Bottom Sediment Granulometric Data for the...

Optimization of Laminated Composite Structures

DEFF Research Database (Denmark)

Henrichsen, Søren Randrup

of the contributions of the PhD project are included in the second part of the thesis. Paper A presents a framework for free material optimization where commercially available finite element analysis software is used as analysis tool. Robust buckling optimization of laminated composite structures by including...... allows for a higher degree of tailoring of the resulting material. To enable better utilization of the composite materials, optimum design procedures can be used to assist the engineer. This PhD thesis is focused on developing numerical methods for optimization of laminated composite structures...... nonlinear analysis of structures, buckling and post-buckling analysis of structures, and formulations for optimization of structures considering stiffness, buckling, and post-buckling criteria. Lastly, descriptions, main findings, and conclusions of the papers are presented. The papers forming the basis...

Stiffened Composite Fuselage Barrel Optimization

Science.gov (United States)

Movva, R. G.; Mittal, A.; Agrawal, K.; Upadhyay, C. S.

2012-07-01

In a typical commercial transport aircraft, Stiffened skin panels and frames contribute around 40% of the fuselage weight. In the current study a stiffened composite fuselage skin panel optimization engine is developed for optimization of the layups of composite panels and stringers using Genetic Algorithm (GA). The skin and stringers of the fuselage section are optimized for the strength and the stability requirements. The selection of the GA parameters considered for the optimization is arrived by performing case studies on selected problems. The optimization engine facilitates in carrying out trade studies for selection of the optimum ply layup and material combination for the configuration being analyzed. The optimization process is applied on a sample model and the results are presented.

Granulometric determinations and inhalation dose assessment for atmospheric aerosol contaminated by 137Cs

International Nuclear Information System (INIS)

Castellani, C.M.; Luciani, A.; Oliviero, L.; Donato, R.

1996-07-01

During the redevelopment of Brescia freight-yard a measurement campaign of atmospheric aerosol was carried out: in fact a 137 Cs ground contamination, caused by the permanence of wagons carrying iron materials contaminated by this radionuclide, had been found out. During the redevelopment phases of excavation and can filling the workers were exposed to the danger of radioactive aerosol inhalation. The aim of the measurement campaign was to test the aerosol sampling and granulometric analysis methodologies with their sensitivity related to the inhalation dose assessments. The results of both aerosuspended mass and activity, evaluated by means of a portable cascade impactor, are presented. The granulometries have been interpolated with a log normal distribution using an iterative routine minimizing the square deviation between the calculated and experimental data. The results related to the dose assessments are also presented. These evaluations have been carried out using both the granulometric information obtained and the more recent models (ICRP 66) both the total concentration data and the dose coefficients referring to the standard conditions of ICRP 68 and of the Italian law (D.Lgs. 230/95). Furthermore the significance and the reliability of the dose assessments referring to the different methodologies are discussed, also in relation to the possibility of using this sampling methodologies for other radionuclides and different exposure conditions

Accuracy increasing in the nuclear-physical analysis of mineral raw materials of heterogeneous composition

International Nuclear Information System (INIS)

Pak, Yu.; Vdovkin, A.; Pak, D.

2002-01-01

the analysis of heterogeneous raw material by the gamma-albedo method it's necessary to optimize the primary gamma-radiation energy choose depending on the material composition of the raw material, its granulometric composition and to reach the maximal presentability of the analysis. For this a method has been suggested which allows to increase substantially the effective study surface without increasing the analyzed object size. The essence of the method consists in the rotation of the object around its axis relatively to the detector reciprocating parallel to the sample in the process of measuring. The optimal laws of the detector motion and the sample rotation provide for the equal presentability of each unit study surface. The experimental approving of the suggested method showed that the optimization of the methodical and geometrical control parameters in the dynamic measuring conditions allow to increase the accuracy of the analysis of disperse raw materials more that twice as large

por energía de compactación y variación en la granulometría

Directory of Open Access Journals (Sweden)

Oscar Javier Reyes Ortiz

2006-01-01

Full Text Available El objetivo de esta investigación es establecer la influencia en las propiedades dinámicas de unas mezclas asfálticas por cambios en su energía de compactación y su granulometría. Para el desarrollo de la investigación se utilizaron dos tipos de mezcla asfálticas, una mezcla cerrada (0/10 y mezcla abierta (0/20 y la variación de la energía de compactación se realizo mediante cambios en los golpes por cada cara de las briquetas en su proceso de fabricación. La investigación inició con la caracterización de los materiales granulares y el asfalto. Posteriormente se les realizó el ensayo marshall a las mezclas para determinar el porcentaje óptimo de asfalto, el cual se obtuvo de las gráficas de estabilidad, flujo y peso unitario. Finalmente, se realizaron ensayos de módulos dinámicos y ahuellamiento, para poder concluir cual es la energía de compactación óptima que debe tener la mezcla asfáltica, y así, optimizar el diseño y funcionamiento de estructuras de pavimentos flexibles con diferentes tipos de granulometría. Dentro de los resultados se resalta que el mayor módulo dinámico para la mezcla cerrada (0/10 se obtuvo para una energía de compactación de 85 golpes y para la mezcla abierta (0/20 de 75 golpes. Con respecto a la deformación permanente se obtuvo las menores deformaciones para la energía de compactación de 90 golpes en la mezcla cerrada y de 85 golpes para la granulometría abierta.

GRANULOMETRIC AND HUMIC FRACTIONS CARBON STOCKS OF SOIL ORGANIC MATTER UNDER NO-TILLAGE SYSTEM IN UBERABA, BRAZIL

Directory of Open Access Journals (Sweden)

Marcos Gervasio Pereira

2011-12-01

Full Text Available The cover plant use preceding grain crops in Cerrado soil can increase the carbon stocks of chemical and physical fractions of soil organic matter (SOM. The present study aimed to quantify the carbon stocks of SOM granulometric and humic fractions in a Cerrado area under no-tillage system with different cover plant, and compare the results with those from conventional tillage and fallow areas, in Uberaba, MG, Brazil. The implemented cover crops were: millet, tropical grass and sunn hemp. Furthermore, an area was used in fallow and another as a control area (conventional tillage. After cover crop removal, the areas were subdivided for the corn and soybean plantation. Soil samples were collected in the 0.0-0.025, 0.025-0.05, 0.05-0.10 and 0.10-0.20 m depths, with posterior quantification of total organic carbon (TOC levels and chemical and granulometric fractionation of SOM. Humic acid carbon (C-HAF, fulvic acids (C-FAF and humin (C-HUM were quantified through these fractionations. The granulometric fractions consisted in particulate organic matter (POM and mineral organic matter (MOM. Using the carbon levels for each fraction, the respective stocks for each depth were calculated, including the 0.0-0.20 m layer. In the 0.0-0.20 m layer, TOC had the highest stocks for the millet area. The highest POM stocks were found for the corn plantation over sunn hemp and the fallow and soybean area over millet and tropical grass (0.0-0.20 m. In relation to the MOM stocks, the highest values were observed in the areas with millet, sunn hemp and tropical (palisade grass, all superior to those found in the conventional tillage and fallow areas, independent of evaluated culture (0.10-0.20 m. The highest C-HUM stocks were observed in the area with tropical grass (0.025-0.05 m and areas with tropical grass and sunn hemp (0.10-0.20 m, when compared to conventional tillage, independent of evaluated culture (corn and soybean. The highest C-FAH stocks in the depth of 0

Sparse Learning with Stochastic Composite Optimization.

Science.gov (United States)

Zhang, Weizhong; Zhang, Lijun; Jin, Zhongming; Jin, Rong; Cai, Deng; Li, Xuelong; Liang, Ronghua; He, Xiaofei

2017-06-01

In this paper, we study Stochastic Composite Optimization (SCO) for sparse learning that aims to learn a sparse solution from a composite function. Most of the recent SCO algorithms have already reached the optimal expected convergence rate O(1/λT), but they often fail to deliver sparse solutions at the end either due to the limited sparsity regularization during stochastic optimization (SO) or due to the limitation in online-to-batch conversion. Even when the objective function is strongly convex, their high probability bounds can only attain O(√{log(1/δ)/T}) with δ is the failure probability, which is much worse than the expected convergence rate. To address these limitations, we propose a simple yet effective two-phase Stochastic Composite Optimization scheme by adding a novel powerful sparse online-to-batch conversion to the general Stochastic Optimization algorithms. We further develop three concrete algorithms, OptimalSL, LastSL and AverageSL, directly under our scheme to prove the effectiveness of the proposed scheme. Both the theoretical analysis and the experiment results show that our methods can really outperform the existing methods at the ability of sparse learning and at the meantime we can improve the high probability bound to approximately O(log(log(T)/δ)/λT).

Optimal Design of Laminated Composite Beams

DEFF Research Database (Denmark)

Blasques, José Pedro Albergaria Amaral

model for the analysis of laminated composite beams is proposed. The structural analysis is performed in a beam finite element context. The development of a finite element based tool for the analysis of the cross section stiffness properties is described. The resulting beam finite element formulation...... is able to account for the effects of material anisotropy and inhomogeneity in the global response of the beam. Beam finite element models allow for a significant reduction in problem size and are therefore an efficient alternative in computationally intensive applications like optimization frameworks...... design of laminated composite beams. The devised framework is applied in the optimal design of laminated composite beams with different cross section geometries and subjected to different load cases. Design criteria such as beam stiffness, weight, magnitude of the natural frequencies of vibration...

Optimization of wood plastic composite decks

Science.gov (United States)

Ravivarman, S.; Venkatesh, G. S.; Karmarkar, A.; Shivkumar N., D.; Abhilash R., M.

2018-04-01

Wood Plastic Composite (WPC) is a new class of natural fibre based composite material that contains plastic matrix reinforced with wood fibres or wood flour. In the present work, Wood Plastic Composite was prepared with 70-wt% of wood flour reinforced in polypropylene matrix. Mechanical characterization of the composite was done by carrying out laboratory tests such as tensile test and flexural test as per the American Society for Testing and Materials (ASTM) standards. Computer Aided Design (CAD) model of the laboratory test specimen (tensile test) was created and explicit finite element analysis was carried out on the finite element model in non-linear Explicit FE code LS - DYNA. The piecewise linear plasticity (MAT 24) material model was identified as a suitable model in LS-DYNA material library, describing the material behavior of the developed composite. The composite structures for decking application in construction industry were then optimized for cross sectional area and distance between two successive supports (span length) by carrying out various numerical experiments in LS-DYNA. The optimized WPC deck (Elliptical channel-2 E10) has 45% reduced weight than the baseline model (solid cross-section) considered in this study with the load carrying capacity meeting acceptance criterion (allowable deflection & stress) for outdoor decking application.

Granulometric analysis of metallic oxide in ceramic powder form synthesized by different methods

International Nuclear Information System (INIS)

Neiva, L.S.; Simoes, A.N.; Simoes, V.N.; Bispo, A.; Gama, L.

2012-01-01

The aim of this work is to synthesize ceramic powders based on CuO/CeO 2 by means two different synthesis methods, they are: the combustion reaction method and Pechini method. It's part of the aim of this work subject all samples to a synthesized qualitative and quantitative chemical analysis, using the technique EDX and then to a granulometric analysis. The samples of the ceramic powder based on CuO/CeO 2 synthesized in this work by means of the two above synthesis methods, contain various concentrations of CuO ranging between 0 and 0.5 mol. According to the results, only the Pechini method of synthesis exerted a significant and defined influence on the capacity of particle unit agglomeration in these powders (author)

Pantanal of Cáceres: granulometric composition of bottom sediments in the Paraguay River between the outfall of the Cabaçal River and the city of Cáceres, Mato Grosso, Brazil

Directory of Open Access Journals (Sweden)

Gustavo Roberto dos Santos Leandro

2012-08-01

Full Text Available The objective of the study was to verify the granulometric composition of bottom sediments along the longitudinal profile of the Paraguay River between the outfall of the Cabaçal River and the city of Cáceres, Mato Grosso, comprised by the geographic coordinates 15°58’00’’ and 16°50’00’’ South Latitude and 57°40’00’’ and 57°44’00’’ West Longitude. Work activity was conducted to characterize the sites and sediments collection with Van Veen sediment sampler (seven samples; textural analysis of the sediments by the pipetting and sieving method (the method uses a combination of sieving and sedimentation. The Paraguay River exhibits a meandering style with two distinct periods (periodic flooding regime and drought that associated with of bottom sediments alternate processes of erosion, transport and deposition from the discernible changes in the complex landscaping. Thus, the concentration of sand in the bed load transported in the channel (five samples is related to environmental elements and land use. The fine sediments are transferred to the features (bays and ponds and flood plain; the intense fluvial dynamics and the course (alluvial deposition areas contribute to changes in channel and morphologic features (capacity transport and sediment depositions.

Optimal fabrication processes for unidirectional metal-matrix composites: A computational simulation

Science.gov (United States)

Saravanos, D. A.; Murthy, P. L. N.; Morel, M.

1990-01-01

A method is proposed for optimizing the fabrication process of unidirectional metal matrix composites. The temperature and pressure histories are optimized such that the residual microstresses of the composite at the end of the fabrication process are minimized and the material integrity throughout the process is ensured. The response of the composite during the fabrication is simulated based on a nonlinear micromechanics theory. The optimal fabrication problem is formulated and solved with non-linear programming. Application cases regarding the optimization of the fabrication cool-down phases of unidirectional ultra-high modulus graphite/copper and silicon carbide/titanium composites are presented.

Optimal fabrication processes for unidirectional metal-matrix composites - A computational simulation

Science.gov (United States)

Saravanos, D. A.; Murthy, P. L. N.; Morel, M.

1990-01-01

A method is proposed for optimizing the fabrication process of unidirectional metal matrix composites. The temperature and pressure histories are optimized such that the residual microstresses of the composite at the end of the fabrication process are minimized and the material integrity throughout the process is ensured. The response of the composite during the fabrication is simulated based on a nonlinear micromechanics theory. The optimal fabrication problem is formulated and solved with nonlinear programming. Application cases regarding the optimization of the fabrication cool-down phases of unidirectional ultra-high modulus graphite/copper and silicon carbide/titanium composites are presented.

Optimization of composite sandwich cover panels subjected to compressive loadings

Science.gov (United States)

Cruz, Juan R.

1991-01-01

An analysis and design method is presented for the design of composite sandwich cover panels that include the transverse shear effects and damage tolerance considerations. This method is incorporated into a sandwich optimization computer program entitled SANDOP. As a demonstration of its capabilities, SANDOP is used in the present study to design optimized composite sandwich cover panels for for transport aircraft wing applications. The results of this design study indicate that optimized composite sandwich cover panels have approximately the same structural efficiency as stiffened composite cover panels designed to satisfy individual constraints. The results also indicate that inplane stiffness requirements have a large effect on the weight of these composite sandwich cover panels at higher load levels. Increasing the maximum allowable strain and the upper percentage limit of the 0 degree and +/- 45 degree plies can yield significant weight savings. The results show that the structural efficiency of these optimized composite sandwich cover panels is relatively insensitive to changes in core density. Thus, core density should be chosen by criteria other than minimum weight (e.g., damage tolerance, ease of manufacture, etc.).

Recent developments of discrete material optimization of laminated composite structures

DEFF Research Database (Denmark)

Lund, Erik; Sørensen, Rene

2015-01-01

This work will give a quick summary of recent developments of the Discrete Material Optimization approach for structural optimization of laminated composite structures. This approach can be seen as a multi-material topology optimization approach for selecting the best ply material and number...... of plies in a laminated composite structure. The conceptual combinatorial design problem is relaxed to a continuous problem such that well-established gradient based optimization techniques can be applied, and the optimization problem is solved on basis of interpolation schemes with penalization...

Choosing the optimal Pareto composition of the charge material for the manufacture of composite blanks

Science.gov (United States)

Zalazinsky, A. G.; Kryuchkov, D. I.; Nesterenko, A. V.; Titov, V. G.

2017-12-01

The results of an experimental study of the mechanical properties of pressed and sintered briquettes consisting of powders obtained from a high-strength VT-22 titanium alloy by plasma spraying with additives of PTM-1 titanium powder obtained by the hydride-calcium method and powder of PV-N70Yu30 nickel-aluminum alloy are presented. The task is set for the choice of an optimal charge material composition of a composite material providing the required mechanical characteristics and cost of semi-finished products and items. Pareto optimal values for the composition of the composite material charge have been obtained.

Topology Optimization of Lightweight Lattice Structural Composites Inspired by Cuttlefish Bone

Science.gov (United States)

Hu, Zhong; Gadipudi, Varun Kumar; Salem, David R.

2018-03-01

Lattice structural composites are of great interest to various industries where lightweight multifunctionality is important, especially aerospace. However, strong coupling among the composition, microstructure, porous topology, and fabrication of such materials impedes conventional trial-and-error experimental development. In this work, a discontinuous carbon fiber reinforced polymer matrix composite was adopted for structural design. A reliable and robust design approach for developing lightweight multifunctional lattice structural composites was proposed, inspired by biomimetics and based on topology optimization. Three-dimensional periodic lattice blocks were initially designed, inspired by the cuttlefish bone microstructure. The topologies of the three-dimensional periodic blocks were further optimized by computer modeling, and the mechanical properties of the topology optimized lightweight lattice structures were characterized by computer modeling. The lattice structures with optimal performance were identified.

Spline Approximation-Based Optimization of Multi-component Disperse Reinforced Composites

Directory of Open Access Journals (Sweden)

Yu. I. Dimitrienko

2015-01-01

Full Text Available The paper suggests an algorithm for solving the problems of optimal design of multicomponent disperse-reinforced composite materials, which properties are defined by filler concentrations and are independent of their shape. It formulates the problem of conditional optimization of a composite with restrictions on its effective parameters - the elasticity modulus, tension and compression strengths, and heat-conductivity coefficient with minimized composite density. The effective characteristics of a composite were computed by finite-element solving the auxiliary local problems of elasticity and heat-conductivity theories appearing when the asymptotic averaging method is applied.The algorithm suggested to solve the optimization problem includes the following main stages:1 finding a set of solutions for direct problem to calculate the effective characteristics;2 constructing the curves of effective characteristics versus filler concentrations by means of approximating functions, which are offered for use as a thin plate spline with smoothing;3 constructing a set of points to satisfy restrictions and a boundary of the point set to satisfy restrictions obtaining, as a result, a contour which can be parameterized;4 defining a global density minimum over the contour through psi-transformation.A numerical example of solving the optimization problem was given for a dispersereinforced composite with two types of fillers being hollow microspheres: glass and phenolic. It was shown that the suggested algorithm allows us to find optimal filler concentrations efficiently enough.

Reassessment and comparison of natural radioactivity levels in relation to granulometric contents of recently excavated major river sediments

International Nuclear Information System (INIS)

Ramasamy, V.; Suresh, G.; Rajkumar, P.; Murugesan, S.; Mullainathan, S.; Meenakshisundaram, V.

2012-01-01

River sediment depositions on the bottom of rivers most frequently consist of sand and gravel particles, which make them particularly valuable for the building construction. Knowledge of radioactivity present in building material enables one to assess any possible radiological hazard to mankind by the use of such materials. The natural radionuclide ( 238 U, 232 Th and 40 K) contents have been analyzed for the recently excavated sediment samples of Cauvery, Vellar, Ponnaiyar and Palaru rivers with an aim of evaluating the radiation hazard nature. To know the radiological characteristics of the sediment, the different radiological parameters are calculated. Natural radioactivity level is higher in Palaru river and it is lower in Vellar river sediments. In all the rivers, concentration of 238 U is decreased, and concentrations of 232 Th and 40 K are increased towards the river mouth. Granulometric analysis shows that the sand is the main constituent in all the river sediment samples. Content of sand is gradually decreased, and contents of silt and clay are gradually increased towards the river mouth. Cluster analysis was carried out to find the similarity level between the radioactivity and granulometric measurements. The radioactivity level of all the four river sediments mainly depends upon the contents of silt and clay. Averages of the all calculated radiation hazard indices are lower than recommended level in Cauvery, Vellar and Ponnaiyar river sediments. Therefore, the sediment of the above rivers does not pose any significant radiological threat to the population when it is used as a building construction material. (author)

Evaluación de diferentes granulometrías de calcio en la alimentación de gallinas ponedoras

OpenAIRE

Rosa Angélica Sanmiguel-Plazas; Giovanny Rodrigo Mejía-Rojas; Luisa María Lozano-Covaleda; Román David Castañeda-Serrano

2016-01-01

En los últimos años, diversos estudios se han realizado para evaluar el efecto de la granulometría del calcio en la alimentación de gallinas ponedoras, dada su importancia en la eficiencia de la absorción de este mineral para la calcificación del huevo, especialmente en épocas en las que el ave disminuye el consumo de alimento; sin embargo, los resultados obtenidos son controvertidos. En el presente trabajo se propuso evaluar el efecto del tamaño de la partícula de calcio sobre el porcentaje ...

Multi-objective/loading optimization for rotating composite flexbeams

Science.gov (United States)

Hamilton, Brian K.; Peters, James R.

1989-01-01

With the evolution of advanced composites, the feasibility of designing bearingless rotor systems for high speed, demanding maneuver envelopes, and high aircraft gross weights has become a reality. These systems eliminate the need for hinges and heavily loaded bearings by incorporating a composite flexbeam structure which accommodates flapping, lead-lag, and feathering motions by bending and twisting while reacting full blade centrifugal force. The flight characteristics of a bearingless rotor system are largely dependent on hub design, and the principal element in this type of system is the composite flexbeam. As in any hub design, trade off studies must be performed in order to optimize performance, dynamics (stability), handling qualities, and stresses. However, since the flexbeam structure is the primary component which will determine the balance of these characteristics, its design and fabrication are not straightforward. It was concluded that: pitchcase and snubber damper representations are required in the flexbeam model for proper sizing resulting from dynamic requirements; optimization is necessary for flexbeam design, since it reduces the design iteration time and results in an improved design; and inclusion of multiple flight conditions and their corresponding fatigue allowables is necessary for the optimization procedure.

Discrete Material and Thickness Optimization of laminated composite structures including failure criteria

DEFF Research Database (Denmark)

Lund, Erik

2017-01-01

This work extends the Discrete Material and Thickness Optimization approach to structural optimization problems where strength considerations in the form of failure criteria are taken into account for laminated composite structures. It takes offset in the density approaches applied for stress...... constrained topology optimization of single-material problems and develops formulations for multi-material topology optimization problems applied for laminated composite structures. The method can be applied for both stress- and strain-based failure criteria. The large number of local constraints is reduced...

Robust buckling optimization of laminated composite structures using discrete material optimization considering “worst” shape imperfections

DEFF Research Database (Denmark)

Henrichsen, Søren Randrup; Lindgaard, Esben; Lund, Erik

2015-01-01

Robust buckling optimal design of laminated composite structures is conducted in this work. Optimal designs are obtained by considering geometric imperfections in the optimization procedure. Discrete Material Optimization is applied to obtain optimal laminate designs. The optimal geometric...... imperfection is represented by the “worst” shape imperfection. The two optimization problems are combined through the recurrence optimization. Hereby the imperfection sensitivity of the considered structures can be studied. The recurrence optimization is demonstrated through a U-profile and a cylindrical panel...... example. The imperfection sensitivity of the optimized structure decreases during the recurrence optimization for both examples, hence robust buckling optimal structures are designed....

Optimal Design of Composite Structures Under Manufacturing Constraints

DEFF Research Database (Denmark)

Marmaras, Konstantinos

algorithms to perform the global optimization. The efficiency of the proposed models is examined on a set of well–defined discrete multi material and thickness optimization problems originating from the literature. The inclusion of manufacturing limitations along with structural considerations in the early...... mixed integer 0–1 programming problems. The manufacturing constraints have been treated by developing explicit models with favorable properties. In this thesis we have developed and implemented special purpose global optimization methods and heuristic techniques for solving this class of problems......This thesis considers discrete multi material and thickness optimization of laminated composite structures including local failure criteria and manufacturing constraints. Our models closely follow an immediate extension of the Discrete Material Optimization scheme, which allows simultaneous...

Improvement of the steel quality through zirconia base ceramic filter

International Nuclear Information System (INIS)

Santos, Benedito M.; Foschini, Cesar R.; Santos, Ieda M.G.; Pinheiro, Adriano S.; Paskocimas, Carlos A.; Leite, Edson R.; Longo, Elson

1997-01-01

At the end of production, the steel presents inclusions own to the making process. Ceramics filters, with controlled porosity, are being produced to eliminate the impurities, so as to increase the good quality steel production. This work studies the optimization of the zirconia filters composition and production for siderurgical processes application. The study was done through the granulometric control, using BET, XRD and Hg Porosimetry. (author)

Optimal composition of fluid-replacement beverages.

Science.gov (United States)

Baker, Lindsay B; Jeukendrup, Asker E

2014-04-01

The objective of this article is to provide a review of the fundamental aspects of body fluid balance and the physiological consequences of water imbalances, as well as discuss considerations for the optimal composition of a fluid replacement beverage across a broad range of applications. Early pioneering research involving fluid replacement in persons suffering from diarrheal disease and in military, occupational, and athlete populations incurring exercise- and/or heat-induced sweat losses has provided much of the insight regarding basic principles on beverage palatability, voluntary fluid intake, fluid absorption, and fluid retention. We review this work and also discuss more recent advances in the understanding of fluid replacement as it applies to various populations (military, athletes, occupational, men, women, children, and older adults) and situations (pathophysiological factors, spaceflight, bed rest, long plane flights, heat stress, altitude/cold exposure, and recreational exercise). We discuss how beverage carbohydrate and electrolytes impact fluid replacement. We also discuss nutrients and compounds that are often included in fluid-replacement beverages to augment physiological functions unrelated to hydration, such as the provision of energy. The optimal composition of a fluid-replacement beverage depends upon the source of the fluid loss, whether from sweat, urine, respiration, or diarrhea/vomiting. It is also apparent that the optimal fluid-replacement beverage is one that is customized according to specific physiological needs, environmental conditions, desired benefits, and individual characteristics and taste preferences.

Improved Vegetation Profiles with GOCI Imagery Using Optimized BRDF Composite

Directory of Open Access Journals (Sweden)

Sang-il Kim

2016-01-01

Full Text Available The purpose of this study was to optimize a composite method for the Geostationary Ocean Color Imager (GOCI, which is the first geostationary ocean color sensor in the world. Before interpreting the sensitivity of each composite with ground measurements, we evaluated the accuracy of bidirectional reflectance distribution function (BRDF performance by comparing modeled surface reflectance from BRDF simulation with GOCI-measured surface reflectance according to composite period. The root mean square error values for modeled and measured surface reflectance showed reasonable accuracy for all of composite days since each BRDF composite period includes at least seven cloud-free angular sampling for all BRDF performances. Also, GOCI-BRDF-adjusted NDVIs with four different composite periods were compared with field-observation NDVI and we interpreted the sensitivity of temporal crop dynamics of GOCI-BRDF-adjusted NDVIs. The results showed that vegetation index seasonal profiles appeared similar to vegetation growth curves in both field observations from crop scans and GOCI normalized difference vegetation index (NDVI data. Finally, we showed that a 12-day composite period was optimal in terms of BRDF simulation accuracy, surface coverage, and real-time sensitivity.

OPTIMIZATION OF MEDIUM COMPOSITIONS FOR SACCHAROMYCES BOULARDII BY BOX-BEHNKEN DESIGN

Directory of Open Access Journals (Sweden)

ZHANGTENG LEI

2016-12-01

Full Text Available Based on the previous experimental results, the Box-Behnken design (BBD was employed to study the individual and interactive effects of sucrose, malt extract, calf serum and sodium citrate on the growth of Saccharomyces boulardii, and the optimum medium compositions were obtained. Meanwhile, the optical density (OD in the fermentation suspension was measured at 560 nm after 36 h of incubation. It is shown that the optimized medium compositions were 36.28 g·L-1 sucrose, 6.38 g·L-1 malt extract, 5.69 g·L-1 calf serum and 5.3 g·L-1 sodium citrate. The result indicated that the growth of S. boulardii could increase significantly in the optimized medium, and the OD560nm value reached 1.397 ± 0.013 after 36 h, which increased 18.59 % compared with that of pre-optimized medium. In addition, the OD560nm value 1.397 ± 0.013 in the optimized medium was very closely to the expected value 1.394. This result suggested that optimization of medium compositions for S. boulardii by BBD in this study was reliable and effective.

Combinatorial Optimization for Energy Saving in Nickel Industry Non-Newtonian Fluid Pumping System

International Nuclear Information System (INIS)

Hernández Ramírez, Gabriel; Legra Lobaina, Aristides; Columbié Navarro, Angel; Marcos Aníbal León Segovia

2017-01-01

In the present work a study of the influence of the rheological parameters of the lateritic hydromixtures with the energetic ones of the pumping systems that guarantee the productivity of nickel company 'Commander Pedro Sotto Alba' is carried out. From an experimental study and through an estimator, the rheological parameters are modeled as a function of the factors: temperature, solids content, chemical and granulometric composition. From an appropriate discretization of the model of the lateritic hydrometer pumping system and the application of a Discrete Combination Optimization Double Sequencing procedure, the operating parameters of this system were obtained, in order to guarantee a flow rate of 1600 m3 / h and one Adequate solids concentration. It is concluded that the use of a mathematical model that relates the rheological parameters of the lateritic pulp and the energy parameters of the pumping system, guarantee the metallurgical and energy efficiency in the acid leaching process with an average increase in production between 1000-1500 T Ni + Co / y and an energy saving of 30 MWh /year. (author)

Comparative study for the design of optimal composite pressure vessels

International Nuclear Information System (INIS)

Butt, A.M.; Haq, S.W.U.

2009-01-01

Composite pressure vessels require special design attention to the dome region because of the varying wind angles generated using the filament winding process. Geometric variations in the dome region cause the fiber to change angels and thickness and hence offer difficulty to acquire a constant stress profile (isotensoid). Therefore a dome contour which allows an isotensoid behavior is the required structure. Two design methods to generate dome profiles for similar dome openings were investigated namely Netting Analysis and Optimal Design method. Both methods assume that loads are carried by the fiber alone (monotropic) ignoring the complete composite behavior. Former method produced a lower dome internal volume and a higher fiber thickness as compared to the later optimal design method when studied against different normalized dome opening radiuses. The optimal dome contour was studied in ANSYS with a trial design. The dome was considered to have transversely isotropic property with a dome contour based on monotropic model. While investigating the dome with non linear large displacement finite element analysis, the dome still exhibited isotensoid behavior with transverse isotropic material assignment. Elliptic integrals were used to generate the optimal dome contours and hence elliptic dome contours were formed which were isotensoid in nature with complete composite representation. (author)

Development and Application of a Tool for Optimizing Composite Matrix Viscoplastic Material Parameters

Science.gov (United States)

Murthy, Pappu L. N.; Naghipour Ghezeljeh, Paria; Bednarcyk, Brett A.

2018-01-01

This document describes a recently developed analysis tool that enhances the resident capabilities of the Micromechanics Analysis Code with the Generalized Method of Cells (MAC/GMC) and its application. MAC/GMC is a composite material and laminate analysis software package developed at NASA Glenn Research Center. The primary focus of the current effort is to provide a graphical user interface (GUI) capability that helps users optimize highly nonlinear viscoplastic constitutive law parameters by fitting experimentally observed/measured stress-strain responses under various thermo-mechanical conditions for braided composites. The tool has been developed utilizing the MATrix LABoratory (MATLAB) (The Mathworks, Inc., Natick, MA) programming language. Illustrative examples shown are for a specific braided composite system wherein the matrix viscoplastic behavior is represented by a constitutive law described by seven parameters. The tool is general enough to fit any number of experimentally observed stress-strain responses of the material. The number of parameters to be optimized, as well as the importance given to each stress-strain response, are user choice. Three different optimization algorithms are included: (1) Optimization based on gradient method, (2) Genetic algorithm (GA) based optimization and (3) Particle Swarm Optimization (PSO). The user can mix and match the three algorithms. For example, one can start optimization with either 2 or 3 and then use the optimized solution to further fine tune with approach 1. The secondary focus of this paper is to demonstrate the application of this tool to optimize/calibrate parameters for a nonlinear viscoplastic matrix to predict stress-strain curves (for constituent and composite levels) at different rates, temperatures and/or loading conditions utilizing the Generalized Method of Cells. After preliminary validation of the tool through comparison with experimental results, a detailed virtual parametric study is

Optimization of glass composition for the vitrification of nuclear waste at the Savannah River Plant

International Nuclear Information System (INIS)

Soper, P.D.; Roberts, G.J.; Lightner, L.F.; Walker, D.D.; Plodinec, M.J.

1982-01-01

Waste glasses of different compositions were compared in terms of leachability, viscosity, liquidus temperature, and coefficient of expansion. The compositions of the glasses were determined by statistical optimization. Waste glass of the optimized composition is more durable than the current reference composition but can still be processed at low temperature

Optimal serotype compositions for Pneumococcal conjugate vaccination under serotype replacement.

Science.gov (United States)

Nurhonen, Markku; Auranen, Kari

2014-02-01

Pneumococcal conjugate vaccination has proved highly effective in eliminating vaccine-type pneumococcal carriage and disease. However, the potential adverse effects of serotype replacement remain a major concern when implementing routine childhood pneumococcal conjugate vaccination programmes. Applying a concise predictive model, we present a ready-to-use quantitative tool to investigate the implications of serotype replacement on the net effectiveness of vaccination against invasive pneumococcal disease (IPD) and to guide in the selection of optimal vaccine serotype compositions. We utilise pre-vaccination data on pneumococcal carriage and IPD and assume partial or complete elimination of vaccine-type carriage, its replacement by non-vaccine-type carriage, and stable case-to-carrier ratios (probability of IPD per carriage episode). The model predicts that the post-vaccination IPD incidences in Finland for currently available vaccine serotype compositions can eventually decrease among the target age group of children replacement through herd effects, the decrease among the older population is predicted to be much less (20-40%). We introduce a sequential algorithm for the search of optimal serotype compositions and assess the robustness of inferences to uncertainties in data and assumptions about carriage and IPD. The optimal serotype composition depends on the age group of interest and some serotypes may be highly beneficial vaccine types in one age category (e.g. 6B in children), while being disadvantageous in another. The net effectiveness will be improved only if the added serotype has a higher case-to-carrier ratio than the average case-to-carrier ratio of the current non-vaccine types and the degree of improvement in effectiveness depends on the carriage incidence of the serotype. The serotype compositions of currently available pneumococcal vaccines are not optimal and the effectiveness of vaccination in the population at large could be improved by including

Optimal orientation field to manufacture magnetostrictive composites with high magnetostrictive performance

International Nuclear Information System (INIS)

Dong Xufeng; Ou Jinping; Guan Xinchun; Qi Min

2010-01-01

Magnetostrictive properties have relationship with the applied orientation field during the preparation of giant magnetostrictive composites. To understand the dependence of the optimal orientation field on particle volume fraction, composites with 20%, 30% and 50% particles by volume were fabricated by distributing Terfenol-D particles in an unsaturated polyester resin under various orientation fields. Their magnetostrictive properties were tested without pre-stress at room temperature. The results indicate that as the particle volume fraction increases, the optimal orientation field increases. The main reason for this phenomenon is the packing density for the composites with higher particle volume fraction is larger than that for those with lower particle content.

Optimal orientation field to manufacture magnetostrictive composites with high magnetostrictive performance

Energy Technology Data Exchange (ETDEWEB)

Dong Xufeng, E-mail: dongxf@dlut.edu.c [School of Materials Science and Engineering, Dalian University of Technology, Dalian, Liaoning 116024 (China); Ou Jinping [School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian, Liaoning 116024 (China); School of Civil Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150090 (China); Guan Xinchun [School of Civil Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150090 (China); Qi Min [School of Materials Science and Engineering, Dalian University of Technology, Dalian, Liaoning 116024 (China)

2010-11-15

Magnetostrictive properties have relationship with the applied orientation field during the preparation of giant magnetostrictive composites. To understand the dependence of the optimal orientation field on particle volume fraction, composites with 20%, 30% and 50% particles by volume were fabricated by distributing Terfenol-D particles in an unsaturated polyester resin under various orientation fields. Their magnetostrictive properties were tested without pre-stress at room temperature. The results indicate that as the particle volume fraction increases, the optimal orientation field increases. The main reason for this phenomenon is the packing density for the composites with higher particle volume fraction is larger than that for those with lower particle content.

Development of multidisciplinary design optimization procedures for smart composite wings and turbomachinery blades

Science.gov (United States)

Jha, Ratneshwar

Multidisciplinary design optimization (MDO) procedures have been developed for smart composite wings and turbomachinery blades. The analysis and optimization methods used are computationally efficient and sufficiently rigorous. Therefore, the developed MDO procedures are well suited for actual design applications. The optimization procedure for the conceptual design of composite aircraft wings with surface bonded piezoelectric actuators involves the coupling of structural mechanics, aeroelasticity, aerodynamics and controls. The load carrying member of the wing is represented as a single-celled composite box beam. Each wall of the box beam is analyzed as a composite laminate using a refined higher-order displacement field to account for the variations in transverse shear stresses through the thickness. Therefore, the model is applicable for the analysis of composite wings of arbitrary thickness. Detailed structural modeling issues associated with piezoelectric actuation of composite structures are considered. The governing equations of motion are solved using the finite element method to analyze practical wing geometries. Three-dimensional aerodynamic computations are performed using a panel code based on the constant-pressure lifting surface method to obtain steady and unsteady forces. The Laplace domain method of aeroelastic analysis produces root-loci of the system which gives an insight into the physical phenomena leading to flutter/divergence and can be efficiently integrated within an optimization procedure. The significance of the refined higher-order displacement field on the aeroelastic stability of composite wings has been established. The effect of composite ply orientations on flutter and divergence speeds has been studied. The Kreisselmeier-Steinhauser (K-S) function approach is used to efficiently integrate the objective functions and constraints into a single envelope function. The resulting unconstrained optimization problem is solved using the

A Comparative Analyses of Granulometry, Mineral Composition and Major and Trace Element Concentrations in Soils Commonly Ingested by Humans

Directory of Open Access Journals (Sweden)

Veronica M. Ngole-Jeme

2015-07-01

Full Text Available This study compared the granulometric properties, mineralogical composition and concentrations of major and trace element oxides of commonly ingested soils (geophagic soil collected from different countries with a view of understanding how varied they may be in these properties and to understand the possible health implications of ingesting them. Soil samples were collected from three different countries (South Africa, Swaziland and Democratic Republic of Congo (DRC and their granulometric properties, concentrations of major and trace element oxides as well as mineralogical composition determined. Differences were observed in the granulometric properties of geophagic soil from the three different countries with most of them having <20% clay content. The soils also showed varied degrees of weathering with values of Chemical Index of Alteration (CIA and Chemical Index of Weathering (CIW being between 60% and 99.9% respectively. The mineral assemblages of the soils from South Africa and Swaziland were dominated by the primary minerals quartz and feldspar whereas soils from DRC had more of kaolinite, a secondary mineral than primary minerals. Soils from DRC were associated with silt, clay, Al2O3, and CIA unlike most samples from South Africa which were associated with SiO2, sand, K2O, CaO, and MgO. The soils from Swaziland were closely associated with silt, H2O and Fe2O3(t. These associations reflect the mineralogy of the samples. These soils are not likely to serve as nutrient supplements because of the low concentrations of the nutrient elements contained. The coarse texture of the samples may also result in dental destruction during mastication. Sieving of the soils before ingestion to remove coarse particles is recommended to reduce the potential health threat associated with the ingestion of coarse-textured soils.

A Comparative Analyses of Granulometry, Mineral Composition and Major and Trace Element Concentrations in Soils Commonly Ingested by Humans

Science.gov (United States)

Ngole-Jeme, Veronica M.; Ekosse, Georges-Ivo E.

2015-01-01

This study compared the granulometric properties, mineralogical composition and concentrations of major and trace element oxides of commonly ingested soils (geophagic soil) collected from different countries with a view of understanding how varied they may be in these properties and to understand the possible health implications of ingesting them. Soil samples were collected from three different countries (South Africa, Swaziland and Democratic Republic of Congo (DRC)) and their granulometric properties, concentrations of major and trace element oxides as well as mineralogical composition determined. Differences were observed in the granulometric properties of geophagic soil from the three different countries with most of them having soils also showed varied degrees of weathering with values of Chemical Index of Alteration (CIA) and Chemical Index of Weathering (CIW) being between 60% and 99.9% respectively. The mineral assemblages of the soils from South Africa and Swaziland were dominated by the primary minerals quartz and feldspar whereas soils from DRC had more of kaolinite, a secondary mineral than primary minerals. Soils from DRC were associated with silt, clay, Al2O3, and CIA unlike most samples from South Africa which were associated with SiO2, sand, K2O, CaO, and MgO. The soils from Swaziland were closely associated with silt, H2O and Fe2O3(t). These associations reflect the mineralogy of the samples. These soils are not likely to serve as nutrient supplements because of the low concentrations of the nutrient elements contained. The coarse texture of the samples may also result in dental destruction during mastication. Sieving of the soils before ingestion to remove coarse particles is recommended to reduce the potential health threat associated with the ingestion of coarse-textured soils. PMID:26264010

A Fast Optimization Method for Reliability and Performance of Cloud Services Composition Application

Directory of Open Access Journals (Sweden)

Zhao Wu

2013-01-01

Full Text Available At present the cloud computing is one of the newest trends of distributed computation, which is propelling another important revolution of software industry. The cloud services composition is one of the key techniques in software development. The optimization for reliability and performance of cloud services composition application, which is a typical stochastic optimization problem, is confronted with severe challenges due to its randomness and long transaction, as well as the characteristics of the cloud computing resources such as openness and dynamic. The traditional reliability and performance optimization techniques, for example, Markov model and state space analysis and so forth, have some defects such as being too time consuming and easy to cause state space explosion and unsatisfied the assumptions of component execution independence. To overcome these defects, we propose a fast optimization method for reliability and performance of cloud services composition application based on universal generating function and genetic algorithm in this paper. At first, a reliability and performance model for cloud service composition application based on the multiple state system theory is presented. Then the reliability and performance definition based on universal generating function is proposed. Based on this, a fast reliability and performance optimization algorithm is presented. In the end, the illustrative examples are given.

Optimization Formulations for the Maximum Nonlinear Buckling Load of Composite Structures

DEFF Research Database (Denmark)

Lindgaard, Esben; Lund, Erik

2011-01-01

This paper focuses on criterion functions for gradient based optimization of the buckling load of laminated composite structures considering different types of buckling behaviour. A local criterion is developed, and is, together with a range of local and global criterion functions from literature......, benchmarked on a number of numerical examples of laminated composite structures for the maximization of the buckling load considering fiber angle design variables. The optimization formulations are based on either linear or geometrically nonlinear analysis and formulated as mathematical programming problems...... solved using gradient based techniques. The developed local criterion is formulated such it captures nonlinear effects upon loading and proves useful for both analysis purposes and as a criterion for use in nonlinear buckling optimization. © 2010 Springer-Verlag....

Optimizing Thermal-Elastic Properties of C/C–SiC Composites Using a Hybrid Approach and PSO Algorithm

Science.gov (United States)

Xu, Yingjie; Gao, Tian

2016-01-01

Carbon fiber-reinforced multi-layered pyrocarbon–silicon carbide matrix (C/C–SiC) composites are widely used in aerospace structures. The complicated spatial architecture and material heterogeneity of C/C–SiC composites constitute the challenge for tailoring their properties. Thus, discovering the intrinsic relations between the properties and the microstructures and sequentially optimizing the microstructures to obtain composites with the best performances becomes the key for practical applications. The objective of this work is to optimize the thermal-elastic properties of unidirectional C/C–SiC composites by controlling the multi-layered matrix thicknesses. A hybrid approach based on micromechanical modeling and back propagation (BP) neural network is proposed to predict the thermal-elastic properties of composites. Then, a particle swarm optimization (PSO) algorithm is interfaced with this hybrid model to achieve the optimal design for minimizing the coefficient of thermal expansion (CTE) of composites with the constraint of elastic modulus. Numerical examples demonstrate the effectiveness of the proposed hybrid model and optimization method. PMID:28773343

Preparation, optimization and property of PVA-HA/PAA composite hydrogel.

Science.gov (United States)

Chen, Kai; Liu, Jinlong; Yang, Xuehui; Zhang, Dekun

2017-09-01

PVA-HA/PAA composite hydrogel is prepared by freezing-thawing, PEG dehydration and annealing method. Orthogonal design method is used to choose the optimization combination. Results showed that HA and PVA have the maximum effect on water content. PVA and freezing-thawing cycles have the maximum effect on creep resistance and stress relaxation rate of hydrogel. Annealing temperature and freezing-thawing cycles have the maximum effect on compressive elastic modulus of hydrogel. Comparing with the water content and mechanical properties of 16 kinds of combination, PVA-HA/PAA composite hydrogel with freezing-thawing cycles of 3, annealing temperature of 120°C, PVA of 16%, HA of 2%, PAA of 4% has the optimization comprehensive properties. PVA-HA/PAA composite hydrogel has a porous network structure. There are some interactions between PVA, HA and PAA in hydrogel and the properties of hydrogel are strengthened. The annealing treatment improves the crystalline and crosslinking of hydrogel. Therefore, the annealing PVA-HA/PAA composite hydrogel has good thermostability, strength and mechanical properties. It also has good lubrication property and its friction coefficient is relative low. Copyright © 2017 Elsevier B.V. All rights reserved.

Topology optimization of periodic microstructures for enhanced dynamic properties of viscoelastic composite materials

DEFF Research Database (Denmark)

Andreassen, Erik; Jensen, Jakob Søndergaard

2014-01-01

We present a topology optimization method for the design of periodic composites with dissipative materials for maximizing the loss/attenuation of propagating waves. The computational model is based on a finite element discretization of the periodic unit cell and a complex eigenvalue problem...... with a prescribed wave frequency. The attenuation in the material is described by its complex wavenumber, and we demonstrate in several examples optimized distributions of a stiff low loss and a soft lossy material in order to maximize the attenuation. In the examples we cover different frequency ranges and relate...... the results to previous studies on composites with high damping and stiffness based on quasi-static conditions for low frequencies and the bandgap phenomenon for high frequencies. Additionally, we consider the issues of stiffness and connectivity constraints and finally present optimized composites...

A genetic algorithm for the optimization of fiber angles in composite laminates

International Nuclear Information System (INIS)

Hwang, Shun Fa; Hsu, Ya Chu; Chen, Yuder

2014-01-01

A genetic algorithm for the optimization of composite laminates is proposed in this work. The well-known roulette selection criterion, one-point crossover operator, and uniform mutation operator are used in this genetic algorithm to create the next population. To improve the hill-climbing capability of the algorithm, adaptive mechanisms designed to adjust the probabilities of the crossover and mutation operators are included, and the elite strategy is enforced to ensure the quality of the optimum solution. The proposed algorithm includes a new operator called the elite comparison, which compares and uses the differences in the design variables of the two best solutions to find possible combinations. This genetic algorithm is tested in four optimization problems of composite laminates. Specifically, the effect of the elite comparison operator is evaluated. Results indicate that the elite comparison operator significantly accelerates the convergence of the algorithm, which thus becomes a good candidate for the optimization of composite laminates.

Data-driven design optimization for composite material characterization

Science.gov (United States)

John G. Michopoulos; John C. Hermanson; Athanasios Iliopoulos; Samuel G. Lambrakos; Tomonari Furukawa

2011-06-01

The main goal of the present paper is to demonstrate the value of design optimization beyond its use for structural shape determination in the realm of the constitutive characterization of anisotropic material systems such as polymer matrix composites with or without damage. The approaches discussed are based on the availability of massive experimental data...

Numerical optimization of composite hip endoprostheses under different loading conditions

Science.gov (United States)

Blake, T. A.; Davy, D. T.; Saravanos, D. A.; Hopkins, D. A.

1992-01-01

The optimization of composite hip implants was investigated. Emphasis was placed on the effect of shape and material tailoring of the implant to improve the implant-bone interaction. A variety of loading conditions were investigated to better understand the relationship between loading and optimization outcome. Comparisons of the initial and optimal models with more complex 3D finite element models were performed. The results indicate that design improvements made using this method result in similar improvements in the 3D models. Although the optimization outcomes were significantly affected by the choice of loading conditions, certain trends were observed that were independent of the applied loading.

Optimal Location of Piezoelectric Patch on Composite Structure using Viewing Method

Science.gov (United States)

Samyal, Rahul; Bagha, Ashok K.

2017-08-01

A useful material which is manufactured by mixing of two or three different materials in homogeneous level is termed as composite material. In now day’s composite materials are used in wide area such as aerospace, automobiles, satellite, bullet proof jackets, rotor blades etc. In this paper modal analysis of composite material, mixture of polyester as matrix and glass as fiber, is carried out by using ABAQUS software. The modal analysis of composite material for fiber orientation 450 is carried out. In this paper by viewing the different mode shapes of the composite material, the optimal location of piezoelectric patch is carried out.

A review of optimization techniques used in the design of fibre composite structures for civil engineering applications

International Nuclear Information System (INIS)

Awad, Ziad K.; Aravinthan, Thiru; Zhuge, Yan; Gonzalez, Felipe

2012-01-01

Highlights: → We reviewed existing optimization techniques of fibre composite structures. → Proposed an improved methodology for design optimization. → Comparison showed the MRDO is most suitable. -- Abstract: Fibre composite structures have become the most attractive candidate for civil engineering applications. Fibre reinforced plastic polymer (FRP) composite materials have been used in the rehabilitation and replacement of the old degrading traditional structures or build new structures. However, the lack of design standards for civil infrastructure limits their structural applications. The majority of the existing applications have been designed based on the research and guidelines provided by the fibre composite manufacturers or based on the designer's experience. It has been a tendency that the final structure is generally over-designed. This paper provides a review on the available studies related to the design optimization of fibre composite structures used in civil engineering such as; plate, beam, box beam, sandwich panel, bridge girder, and bridge deck. Various optimization methods are presented and compared. In addition, the importance of using the appropriate optimization technique is discussed. An improved methodology, which considering experimental testing, numerical modelling, and design constrains, is proposed in the paper for design optimization of composite structures.

Material Optimization of Carbon/Epoxy Composite Rotor for Spacecraft Energy Storage

OpenAIRE

R Varatharajoo; M Salit; G Hong

2016-01-01

An investigation to optimize the carbon/epoxy composite rotor is performed for the spacecraft energy storage application. A highspeed multi-layer rotor design is proposed and different composite materials are tested to achieve the most suitable recipe. First, the analytical rotor evaluation is performed to establish a reliable numerical rotor model. Then, finite element analysis (FEA) is employed in order to optimise the multi-layer composite rotor design. Subsequently, the modal analysis is ...

Topology optimization of compliant adaptive wing leading edge with composite materials

Directory of Open Access Journals (Sweden)

Tong Xinxing

2014-12-01

Full Text Available An approach for designing the compliant adaptive wing leading edge with composite material is proposed based on the topology optimization. Firstly, an equivalent constitutive relationship of laminated glass fiber reinforced epoxy composite plates has been built based on the symmetric laminated plate theory. Then, an optimization objective function of compliant adaptive wing leading edge was used to minimize the least square error (LSE between deformed curve and desired aerodynamics shape. After that, the topology structures of wing leading edge of different glass fiber ply-orientations were obtained by using the solid isotropic material with penalization (SIMP model and sensitivity filtering technique. The desired aerodynamics shape of compliant adaptive wing leading edge was obtained based on the proposed approach. The topology structures of wing leading edge depend on the glass fiber ply-orientation. Finally, the corresponding morphing experiment of compliant wing leading edge with composite materials was implemented, which verified the morphing capability of topology structure and illustrated the feasibility for designing compliant wing leading edge. The present paper lays the basis of ply-orientation optimization for compliant adaptive wing leading edge in unmanned aerial vehicle (UAV field.

Multi-Response Parameter Interval Sensitivity and Optimization for the Composite Tape Winding Process

Science.gov (United States)

Yu, Tao; Kang, Chao; Zhao, Pan

2018-01-01

The composite tape winding process, which utilizes a tape winding machine and prepreg tapes, provides a promising way to improve the quality of composite products. Nevertheless, the process parameters of composite tape winding have crucial effects on the tensile strength and void content, which are closely related to the performances of the winding products. In this article, two different object values of winding products, including mechanical performance (tensile strength) and a physical property (void content), were respectively calculated. Thereafter, the paper presents an integrated methodology by combining multi-parameter relative sensitivity analysis and single-parameter sensitivity analysis to obtain the optimal intervals of the composite tape winding process. First, the global multi-parameter sensitivity analysis method was applied to investigate the sensitivity of each parameter in the tape winding processing. Then, the local single-parameter sensitivity analysis method was employed to calculate the sensitivity of a single parameter within the corresponding range. Finally, the stability and instability ranges of each parameter were distinguished. Meanwhile, the authors optimized the process parameter ranges and provided comprehensive optimized intervals of the winding parameters. The verification test validated that the optimized intervals of the process parameters were reliable and stable for winding products manufacturing. PMID:29385048

Petri Net-Based R&D Process Modeling and Optimization for Composite Materials

Directory of Open Access Journals (Sweden)

Xiaomei Hu

2013-01-01

Full Text Available Considering the current R&D process for new composite materials involves some complex details, such as formula design, specimen/sample production, materials/sample test, assessment, materials/sample feedback from customers, and mass production, the workflow model of Petri net-based R&D process for new composite materials’ is proposed. By analyzing the time property of the whole Petri net, the optimized model for new composite materials R&D workflow is further proposed. By analyzing the experiment data and application in some materials R&D enterprise, it is demonstrated that the workflow optimization model shortens the period of R&D on new materials for 15%, definitely improving the R&D efficiency. This indicates the feasibility and availability of the model.

Composite Differential Evolution with Modified Oracle Penalty Method for Constrained Optimization Problems

Directory of Open Access Journals (Sweden)

Minggang Dong

2014-01-01

Full Text Available Motivated by recent advancements in differential evolution and constraints handling methods, this paper presents a novel modified oracle penalty function-based composite differential evolution (MOCoDE for constrained optimization problems (COPs. More specifically, the original oracle penalty function approach is modified so as to satisfy the optimization criterion of COPs; then the modified oracle penalty function is incorporated in composite DE. Furthermore, in order to solve more complex COPs with discrete, integer, or binary variables, a discrete variable handling technique is introduced into MOCoDE to solve complex COPs with mix variables. This method is assessed on eleven constrained optimization benchmark functions and seven well-studied engineering problems in real life. Experimental results demonstrate that MOCoDE achieves competitive performance with respect to some other state-of-the-art approaches in constrained optimization evolutionary algorithms. Moreover, the strengths of the proposed method include few parameters and its ease of implementation, rendering it applicable to real life. Therefore, MOCoDE can be an efficient alternative to solving constrained optimization problems.

Optimization of fast disintegration tablets using pullulan as diluent by central composite experimental design

OpenAIRE

Patel, Dipil; Chauhan, Musharraf; Patel, Ravi; Patel, Jayvadan

2012-01-01

The objective of this work was to apply central composite experimental design to investigate main and interaction effect of formulation parameters in optimizing novel fast disintegration tablets formulation using pullulan as diluents. Face centered central composite experimental design was employed to optimize fast disintegration tablet formulation. The variables studied were concentration of diluents (pullulan, X1), superdisintigrant (sodium starch glycolate, X2), and direct compression aid ...

Optimization of Composite Material System and Lay-up to Achieve Minimum Weight Pressure Vessel

Science.gov (United States)

Mian, Haris Hameed; Wang, Gang; Dar, Uzair Ahmed; Zhang, Weihong

2013-10-01

The use of composite pressure vessels particularly in the aerospace industry is escalating rapidly because of their superiority in directional strength and colossal weight advantage. The present work elucidates the procedure to optimize the lay-up for composite pressure vessel using finite element analysis and calculate the relative weight saving compared with the reference metallic pressure vessel. The determination of proper fiber orientation and laminate thickness is very important to decrease manufacturing difficulties and increase structural efficiency. In the present work different lay-up sequences for laminates including, cross-ply [ 0 m /90 n ] s , angle-ply [ ±θ] ns , [ 90/±θ] ns and [ 0/±θ] ns , are analyzed. The lay-up sequence, orientation and laminate thickness (number of layers) are optimized for three candidate composite materials S-glass/epoxy, Kevlar/epoxy and Carbon/epoxy. Finite element analysis of composite pressure vessel is performed by using commercial finite element code ANSYS and utilizing the capabilities of ANSYS Parametric Design Language and Design Optimization module to automate the process of optimization. For verification, a code is developed in MATLAB based on classical lamination theory; incorporating Tsai-Wu failure criterion for first-ply failure (FPF). The results of the MATLAB code shows its effectiveness in theoretical prediction of first-ply failure strengths of laminated composite pressure vessels and close agreement with the FEA results. The optimization results shows that for all the composite material systems considered, the angle-ply [ ±θ] ns is the optimum lay-up. For given fixed ply thickness the total thickness of laminate is obtained resulting in factor of safety slightly higher than two. Both Carbon/epoxy and Kevlar/Epoxy resulted in approximately same laminate thickness and considerable percentage of weight saving, but S-glass/epoxy resulted in weight increment.

Using CCT Diagrams to Optimize the Composition of an As-Rolled Dual-Phase Steel

Science.gov (United States)

Coldren, A. Phillip; Eldis, George T.

1980-03-01

A continuous-cooling transformation (CCT) diagram study was conducted for the purpose of optimizing the composition of a Mn-Si-Cr-Mo as-rolled dual-phase (ARDP) steel. The individual effects of chromium, molybdenum, and silicon on the allowable cooling rates were determined. On the basis of the CCT diagram study and other available information, an optimum composition was selected. Data from recent mill trials at three steel companies, involving steels with compositions in or near the newly recommended range, are presented and compared with earlier mill trial data. The comparison shows that the optimized composition is highly effective in making the steel's properties more uniform and reproducible in the as-rolled condition.

Effects of soil and space on the woody species composition and vegetation structure of three Cerrado phytophysiognomies in the Cerrado-Amazon transition.

Science.gov (United States)

Maracahipes-Santos, L; Lenza, E; Santos, J O; Mews, H A; Oliveira, B

2017-11-01

The Cerrado Biome is considered one of the world's biodiversity hotspots because of its rich biodiversity, the high level of endemism and the increasing threat. The Cerrado is composed by a mosaic of different vegetation types, including physiognomies that vary from grasslands (campo limpo) to savannas (typical cerrado or cerrado sensu stricto) and cerrado woodlands (cerradão). However, the factors that determine the composition of the Cerrado's flora and the structure of the physiognomies that compose this biome are still poorly understood. Here, we investigate the influence of the chemical and granulometric properties of the soil and the effect of geographic distance on the occurrence and abundance of woody species in three Cerrado phytophysiognomies - cerrado woodland (cerradão), dense cerrado savanna and typical cerrado savanna - in the Cerrado-Amazon transition. We tested the hypothesis that the edaphic characteristics and geographic space determine the species composition and the structure of the woody vegetation of these three phytophysiognomies. We demonstrate that the dissimilarities in the structure and composition of the three sites were determined more by space (13% of explanation) than edaphic properties (1%), but primarily by the interaction between these two factors (26%). We conclude that, in situations where the chemical and granulometric properties of the soil are relatively homogeneous, as we found in the present study, geographic distance between sites has a greater influence than variation in the substrate's properties on modelling the occurrence and abundance of the woody plant species in the Cerrado.

Design and Optimization of Composite Automotive Hatchback Using Integrated Material-Structure-Process-Performance Method

Science.gov (United States)

Yang, Xudong; Sun, Lingyu; Zhang, Cheng; Li, Lijun; Dai, Zongmiao; Xiong, Zhenkai

2018-03-01

The application of polymer composites as a substitution of metal is an effective approach to reduce vehicle weight. However, the final performance of composite structures is determined not only by the material types, structural designs and manufacturing process, but also by their mutual restrict. Hence, an integrated "material-structure-process-performance" method is proposed for the conceptual and detail design of composite components. The material selection is based on the principle of composite mechanics such as rule of mixture for laminate. The design of component geometry, dimension and stacking sequence is determined by parametric modeling and size optimization. The selection of process parameters are based on multi-physical field simulation. The stiffness and modal constraint conditions were obtained from the numerical analysis of metal benchmark under typical load conditions. The optimal design was found by multi-discipline optimization. Finally, the proposed method was validated by an application case of automotive hatchback using carbon fiber reinforced polymer. Compared with the metal benchmark, the weight of composite one reduces 38.8%, simultaneously, its torsion and bending stiffness increases 3.75% and 33.23%, respectively, and the first frequency also increases 44.78%.

Detailed design of a lattice composite fuselage structure by a mixed optimization method

Science.gov (United States)

Liu, D.; Lohse-Busch, H.; Toropov, V.; Hühne, C.; Armani, U.

2016-10-01

In this article, a procedure for designing a lattice fuselage barrel is developed. It comprises three stages: first, topology optimization of an aircraft fuselage barrel is performed with respect to weight and structural performance to obtain the conceptual design. The interpretation of the optimal result is given to demonstrate the development of this new lattice airframe concept for the fuselage barrel. Subsequently, parametric optimization of the lattice aircraft fuselage barrel is carried out using genetic algorithms on metamodels generated with genetic programming from a 101-point optimal Latin hypercube design of experiments. The optimal design is achieved in terms of weight savings subject to stability, global stiffness and strain requirements, and then verified by the fine mesh finite element simulation of the lattice fuselage barrel. Finally, a practical design of the composite skin complying with the aircraft industry lay-up rules is presented. It is concluded that the mixed optimization method, combining topology optimization with the global metamodel-based approach, allows the problem to be solved with sufficient accuracy and provides the designers with a wealth of information on the structural behaviour of the novel anisogrid composite fuselage design.

Optimization of concrete composition in radioactive waste management

International Nuclear Information System (INIS)

Plecas, I.; Peric, A.

1995-01-01

Low and intermediate level waste represents 95% of the total wastes that is conditioned into special concrete containers. Since these containers are to protect radioactive waste safely for about 300 years, the selection and precise control of physical and mechanical characteristics of materials is very important. After volume reduction and valuable components recovery, waste materials have to be conditioned for transport, storage and disposal. Conditioning is the waste management step in which radioactive wastes are immobilized and packed. The immobilization processes involve conversation of the wastes to solid forms that reduce the potential for migration or dispersion of radionuclides from the wastes by natural processes during storage, transport and disposal. The immobilization processes involve the use of various matrices of nonradioactive materials, such as concrete, to fix the wastes as monoliths, usually directly in the waste containers used for subsequent handling. In this paper an optimization of concrete container composition, used for storing radioactive waste from nuclear power plants, is presented. Optimization was performed on the composition of the concrete that is used in the container production. In experiments, the authors tried to obtain the best mechanical characteristics of the concrete, varying the weight percentage of the granulate due to its diameter, water-to-cement ratios and type of the cements that were used in preparing the concrete container formulation. Concrete containers, that were optimized in the manner described in this paper, will be in used for the radioactive waste materials final disposal, using the concept of the engineer trench system facilities

About the possibility of obtaining cementitious soil composites of high strength on the basis of belozems of carbonate composition

Science.gov (United States)

Karapetyan, K. A.; Hayroyan, S. G.; Manukyan, E. S.

2018-04-01

The problem of manufacturing high strength cementitious soils based on belozems of carbonate composition, which experience compression (no less than 10 MPa), without application of surface active substances is considered. The portland cement of type 400 was used as a binding agent to develop compositions of cementitious soil composites, and the ordinary pipe water was used to obtain solutions of cementitious soils. The chemical and mineralogical composition of the initial ingredients and the granulometric composition of belozems were determined. The measurements showed that the upper and lower plasticity limits, the optimum moisture content, and the maximal density of the skeleton of belozems, as well as the considered compositions of cementitious soils, are insignificant, while the plasticity index of cementitious soils is less than one for belozems. It is experimentally proved that an increase in the portland cement amount lead to an increase in the compressive strength of cementitious soils with a decreasing speed. But for the same amount of portland cement used in the cementitious soil compositions, the values of the strength ratio of the pieces tested at the age of 60 and 28 days remain the same and are approximately equal to 1.2. A comparison of experimental data showed that it seems to be real to manufacture a cementitious soil on the basis of belozems of carbonate composition, which contain 10% of cement of the weight of dry mixture and have strength more than 10 MPa, without adding any surfactants to the material composition.

Artificial immune system for effective properties optimization of magnetoelectric composites

Science.gov (United States)

Poteralski, Arkadiusz; Dziatkiewicz, Grzegorz

2018-01-01

The optimization problem of the effective properties for magnetoelectric composites is considered. The effective properties are determined by the semi-analytical Mori-Tanaka approach. The generalized Eshelby tensor components are calculated numerically by using the Gauss quadrature method for the integral representation of the inclusion problem. The linear magnetoelectric constitutive equation is used. The effect of orientation of the electromagnetic materials components is taken into account. The optimization problem of the design is formulated and the artificial immune system is applied to solve it.

Structural optimization of the fibre-reinforced composite substructure in a three-unit dental bridge.

Science.gov (United States)

Shi, Li; Fok, Alex S L

2009-06-01

Failures of fixed partial dentures (FPDs) made of fibre-reinforced composites (FRC) have been reported in many clinical and in vitro studies. The types of failure include debonding at the composite-tooth interface, delamination of the veneering material from the FRC substructure and fracture of the pontic. The design of the FRC substructure, i.e. the position and orientation of the fibres, will affect the fracture resistance of the FPD. The purpose of this study was to find an optimal arrangement of the FRC substructure, by means of structural optimization, which could minimize the failure-initiating stresses in a three-unit FPD. A structural optimization method mimicking biological adaptive growth was developed for orthotropic materials such as FRC and incorporated into the finite element (FE) program ABAQUS. Using the program, optimization of the fibre positions and directions in a three-unit FPD was carried out, the aim being to align the fibre directions with those of the maximum principal stresses. The optimized design was then modeled and analyzed to verify the improvements in mechanical performance of the FPD. Results obtained from the optimization suggested that the fibres should be placed at the bottom of the pontic, forming a U-shape substructure that extended into the connectors linking the teeth and the pontic. FE analyses of the optimized design indicated stress reduction in both the veneering composite and at the interface between the veneer and the FRC substructure. The optimized design obtained using FE-based structural optimization can potentially improve the fracture resistance of FPDs by reducing some of the failure-initiating stresses. Optimization methods can therefore be a useful tool to provide sound scientific guidelines for the design of FRC substructures in FPDs.

Multidisciplinary design optimization of the diesel particulate filter in the composite regeneration process

International Nuclear Information System (INIS)

Zhang, Bin; E, Jiaqiang; Gong, Jinke; Yuan, Wenhua; Zuo, Wei; Li, Yu; Fu, Jun

2016-01-01

Highlights: • The multidisciplinary design optimization (MDO) for the DPF is presented. • MDO model and multi-objective functions of the DPF are established. • The optimal design parameters are obtained and DPF’s performances are improved. • The optimized results are verified by experiments. • The composite regeneration process of the optimized DPF allows a higher energy saving. - Abstract: In our previous works, the diesel particulate filter (DPF) using a new composite regeneration mode by coupling microwave and ceria-manganese base catalysts is verified as an effective way to reduce the particulate matter emission of the diesel engine. In order to improve the overall performance of this DPF, its multidisciplinary design optimization (MDO) model is established based on objective functions such as pressure drop, regeneration performance, microwave energy consumption, and thermal shock resistance. Then, the DPF is optimized by using MDO method based on adaptive mutative scale chaos optimization algorithm. The optimization results show that with the help of MDO, DPF’s pressure drop is decreased by 14.5%, regeneration efficiency is increased by 17.3%, microwave energy consumption is decreased by 17.6%, and thermal deformation is decreased by 25.3%. The optimization results are also verified by experiments, and the experimental results indicate that the optimized DPF has larger filtration efficiency, better emission performance and regeneration performance, smaller pressure drop, lower wall temperature and temperature gradient, and lower microwave energy consumption.

Material Optimization of Carbon/Epoxy Composite Rotor for Spacecraft Energy Storage

Directory of Open Access Journals (Sweden)

R Varatharajoo

2016-09-01

Full Text Available An investigation to optimize the carbon/epoxy composite rotor is performed for the spacecraft energy storage application. A highspeed multi-layer rotor design is proposed and different composite materials are tested to achieve the most suitable recipe. First, the analytical rotor evaluation is performed to establish a reliable numerical rotor model. Then, finite element analysis (FEA is employed in order to optimise the multi-layer composite rotor design. Subsequently, the modal analysis is carried out to determine the rotor natural frequencies and mode shapes for a safe operational regime below 50, 000 rpm.

Optimization on microwave absorbing properties of carbon nanotubes and magnetic oxide composite materials

Science.gov (United States)

Mingdong, Chen; Huangzhong, Yu; Xiaohua, Jie; Yigang, Lu

2018-03-01

Based on the physical principle of interaction between electromagnetic field and the electromagnetic medium, the relationship between microwave absorbing coefficient (MAC) and the electromagnetic parameters of materials was established. With the composite materials of nickel ferrite (NiFe2O4), carbon nanotubes (CNTs) and paraffin as an example, optimization on absorbing properties of CNTs/magnetic oxide composite materials was studied at the frequency range of 2-18 GHz, and a conclusion is drawn that the MAC is the biggest at the same frequency, when the CNTs is 10 wt% in the composite materials. Through study on the relationship between complex permeability and MAC, another interesting conclusion is drawn that MAC is obviously affected by the real part of complex permeability, and increasing real part of complex permeability is beneficial for improving absorbing properties. The conclusion of this paper can provide a useful reference for the optimization research on the microwave absorbing properties of CNTs/ferrite composite materials.

Discrete Material Buckling Optimization of Laminated Composite Structures considering "Worst" Shape Imperfections

DEFF Research Database (Denmark)

Henrichsen, Søren Randrup; Lindgaard, Esben; Lund, Erik

2015-01-01

Robust design of laminated composite structures is considered in this work. Because laminated composite structures are often thin walled, buckling failure can occur prior to material failure, making it desirable to maximize the buckling load. However, as a structure always contains imperfections...... and “worst” shape imperfection optimizations to design robust composite structures. The approach is demonstrated on an U-profile where the imperfection sensitivity is monitored, and based on the example it can be concluded that robust designs can be obtained....

[Biotechnological optimization of nutrient composition of fermented dairy drink].

Science.gov (United States)

Donskaya, G A

2014-01-01

The receipt based on the results of carried out studies is substantiated and technology of the new fermented dairy drink containing whole milk and whey with inulin (Jerusalem artichoke extract) and optimizing initial mineral composition of raw material has been developed. The starters ascertaining optimal organoleptic properties of the drink have been selected. It has been established that Jerusalem artichoke and its derivatives in the form of syrups and extracts stimulate fermentative processes of technological microflora, with maximum activity observed with Jerusalem artichoke extract. Physical-chemical and microbiological characteristics of the drink have been defined during storage. The possibility to optimize the nutrient composition of fermented dairy product by means of introducing of Jerusalem artichoke extract into milk-protein base has been demonstrated. It has been calculated that consumption of 100 g of fermented dairy drink enriched with Jerusalem artichoke extract makes it possible to satisfy the physiological needs (recommended daily allowance--RDA) for babies from 0 to 3 months in vitamins B1, B2 and B6 by 25-35% and in minerals P, K, and Ca by 20, 68, 34, 26%. For adults receiving 250 g of fermented beverage meets RDA for vitamins B1, B2 and B6 by 10-19% and in the macronutrients P, K, Ca-by 25-35%. Designed fermented dairy drink supplemented with natural plant ingredient possesses increased antioxidant activity and may be recommended for mass consumption without any limitations.

Hydro-elastic analysis and optimization of a composite marine propeller

DEFF Research Database (Denmark)

Blasques, José Pedro Albergaria Amaral; Berggreen, Christian; Andersen, Poul

2010-01-01

The present paper addresses the design and optimization of a flexible composite marine propeller. The aim is to tailor the laminate to control the deformed shape of the blade and consequently the developed thrust. The development of a hydro-elastic model is presented, and the laminate lay-up which...

Hydro-Elastic Tailoring and Optimization of a Composite Marine Propeller

DEFF Research Database (Denmark)

Blasques, José Pedro Albergaria Amaral; Berggreen, Christian; Andersen, Poul

2008-01-01

The following paper deals with the design and optimization of a flexible composite marine propeller. The blade shape is obtained from an existing high skew metal propeller. The aim is to tailor the laminate to control the elastic couplings and therefore the deformed shape of the blade. The develo...

Optimization of composite panels using neural networks and genetic algorithms

NARCIS (Netherlands)

Ruijter, W.; Spallino, R.; Warnet, Laurent; de Boer, Andries

2003-01-01

The objective of this paper is to present first results of a running study on optimization of aircraft components (composite panels of a typical vertical tail plane) by using Genetic Algorithms (GA) and Neural Networks (NN). The panels considered are standardized to some extent but still there is a

Ply-based Optimization of Laminated Composite Shell Structures under Manufacturing Constraints

DEFF Research Database (Denmark)

Sørensen, Rene; Lund, Erik

2012-01-01

This work concerns a new ply-based parameterization for performing simultaneous material selection and topology optimization of fiber reinforced laminated composite structures while ensuring that a series of different manufacturing constraints are fulfilled. The material selection can either...

Optimal design of damping layers in SMA/GFRP laminated hybrid composites

Science.gov (United States)

Haghdoust, P.; Cinquemani, S.; Lo Conte, A.; Lecis, N.

2017-10-01

This work describes the optimization of the shape profiles for shape memory alloys (SMA) sheets in hybrid layered composite structures, i.e. slender beams or thinner plates, designed for the passive attenuation of flexural vibrations. The paper starts with the description of the material and architecture of the investigated hybrid layered composite. An analytical method, for evaluating the energy dissipation inside a vibrating cantilever beam is developed. The analytical solution is then followed by a shape profile optimization of the inserts, using a genetic algorithm to minimize the SMA material layer usage, while maintaining target level of structural damping. Delamination problem at SMA/glass fiber reinforced polymer interface is discussed. At the end, the proposed methodology has been applied to study the hybridization of a wind turbine layered structure blade with SMA material, in order to increase its passive damping.

Geometric optimization of a neutron detector based on a lithium glass–polymer composite

Energy Technology Data Exchange (ETDEWEB)

Mayer, M., E-mail: mike.f.mayer@gmail.com [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Nattress, J. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Trivelpiece, C. [Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 (United States); Jovanovic, I. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

2015-06-01

We report on the simulation and optimization of a neutron detector based on a glass–polymer composite that achieves high gamma rejection. Lithium glass is embedded in polyvinyltoluene in three geometric forms: disks, rods, and spheres. Optimal shape, geometric configuration, and size of the lithium glass fragments are determined using Geant4 simulations. All geometrical configurations maintain an approximate 7% glass to polymer mass ratio. Results indicate a 125-mm diameter as the optimal detector size for initial prototype design achieving a 10% efficiency for the thermalization of incident fission neutrons from {sup 252}Cf. The geometrical features of a composite detector are shown to have little effect on the intrinsic neutron efficiency, but a significant effect on the gamma rejection is observed. The sphere geometry showed the best overall performance with an intrinsic neutron efficiency of approximately 6% with a gamma rejection better than 10{sup −7} for 280-μm diameter spheres. These promising results provide a motivation for prototype composite detector development based on the simulated designs. - Highlights: • Composite polymer–lithium glass scintillation detector is simulated. • Polymer is considered to be non-scintillating in the simulation. • Three forms of lithium glass are considered: disks, rods, and spheres. • Glass shape has a small effect on neutron efficiency. • Glass shape has a significant effect on gamma rejection.

Granulometric determinations and inhalation dose assessment for atmospheric aerosol contaminated by {sup 137}Cs; Determinazioni granulometriche e valutazioni di dose da inalazione per aerosol atmosferico contaminato da {sup 137}CS

Energy Technology Data Exchange (ETDEWEB)

Castellani, C.M.; Luciani, A. [ENEA, Centro Ricerche `E. Clementel`, Bologna (Italy). Dip. Ambiente; Oliviero, L.; Donato, R. [ENEA, Centro Ricerche Saluggia, Vercelli (Italy). Dip. Ambiente

1996-07-01

During the redevelopment of Brescia freight-yard a measurement campaign of atmospheric aerosol was carried out: in fact a {sup 137}Cs ground contamination, caused by the permanence of wagons carrying iron materials contaminated by this radionuclide, had been found out. During the redevelopment phases of excavation and can filling the workers were exposed to the danger of radioactive aerosol inhalation. The aim of the measurement campaign was to test the aerosol sampling and granulometric analysis methodologies with their sensitivity related to the inhalation dose assessments. The results of both aerosuspended mass and activity, evaluated by means of a portable cascade impactor, are presented. The granulometries have been interpolated with a log normal distribution using an iterative routine minimizing the square deviation between the calculated and experimental data. The results related to the dose assessments are also presented. These evaluations have been carried out using both the granulometric information obtained and the more recent models (ICRP 66) both the total concentration data and the dose coefficients referring to the standard conditions of ICRP 68 and of the Italian law (D.Lgs. 230/95). Furthermore the significance and the reliability of the dose assessments referring to the different methodologies are discussed, also in relation to the possibility of using this sampling methodologies for other radionuclides and different exposure conditions.

Effects of soil and space on the woody species composition and vegetation structure of three Cerrado phytophysiognomies in the Cerrado-Amazon transition

Directory of Open Access Journals (Sweden)

L. Maracahipes-Santos

2017-03-01

Full Text Available Abstract The Cerrado Biome is considered one of the world's biodiversity hotspots because of its rich biodiversity, the high level of endemism and the increasing threat. The Cerrado is composed by a mosaic of different vegetation types, including physiognomies that vary from grasslands (campo limpo to savannas (typical cerrado or cerrado sensu stricto and cerrado woodlands (cerradão. However, the factors that determine the composition of the Cerrado’s flora and the structure of the physiognomies that compose this biome are still poorly understood. Here, we investigate the influence of the chemical and granulometric properties of the soil and the effect of geographic distance on the occurrence and abundance of woody species in three Cerrado phytophysiognomies – cerrado woodland (cerradão, dense cerrado savanna and typical cerrado savanna – in the Cerrado-Amazon transition. We tested the hypothesis that the edaphic characteristics and geographic space determine the species composition and the structure of the woody vegetation of these three phytophysiognomies. We demonstrate that the dissimilarities in the structure and composition of the three sites were determined more by space (13% of explanation than edaphic properties (1%, but primarily by the interaction between these two factors (26%. We conclude that, in situations where the chemical and granulometric properties of the soil are relatively homogeneous, as we found in the present study, geographic distance between sites has a greater influence than variation in the substrate’s properties on modelling the occurrence and abundance of the woody plant species in the Cerrado.

Design Optimization of Laminated Composite Structures with Many Local Strength Criteria

DEFF Research Database (Denmark)

Lund, Erik

2012-01-01

This paper presents different strategies for handling very many local strength criteria in structural optimization of laminated composites. Global strength measures using Kreisselmeier-Steinhauser or p-norm functions are introduced for patch-wise parameterizations, and the efficiency of the metho...

Optimal cure cycle design of a resin-fiber composite laminate

Science.gov (United States)

Hou, Jean W.; Sheen, Jeenson

1987-01-01

A unified computed aided design method was studied for the cure cycle design that incorporates an optimal design technique with the analytical model of a composite cure process. The preliminary results of using this proposed method for optimal cure cycle design are reported and discussed. The cure process of interest is the compression molding of a polyester which is described by a diffusion reaction system. The finite element method is employed to convert the initial boundary value problem into a set of first order differential equations which are solved simultaneously by the DE program. The equations for thermal design sensitivities are derived by using the direct differentiation method and are solved by the DE program. A recursive quadratic programming algorithm with an active set strategy called a linearization method is used to optimally design the cure cycle, subjected to the given design performance requirements. The difficulty of casting the cure cycle design process into a proper mathematical form is recognized. Various optimal design problems are formulated to address theses aspects. The optimal solutions of these formulations are compared and discussed.

Optimization of the piezoelectric response of 0–3 composites: a modeling approach

International Nuclear Information System (INIS)

Chambion, B; Goujon, L; Badie, L; Mugnier, Y; Barthod, C; Galez, C; Wiebel, S; Venet, C

2011-01-01

Finite element modeling is used in this study to optimize the electromechanical behavior of 0–3 composites according to the material properties of their constituents. Our modeling approach considers an 'extended' 2D representative volume element (RVE) with randomly dispersed piezoelectric particles. A variable distribution of their polarization axes is also implemented because a full periodic arrangement of fillers and a unique poling orientation are unrealistic in practice. Comparisons with a simpler RVE and with an analytical model based on the Mori–Tanaka approach are performed as a function of the particle concentration for the elastic, dielectric and piezoelectric homogenized properties. An optimization of the piezoelectric response of 0–3 composites according to material considerations is then computed, allowing it to be shown that the piezoelectric strain coefficient is not the only relevant parameter and that lead-free piezoelectric fillers such as LiNbO 3 and ZnO are competitive alternatives. Finally, the piezoelectric responses of 0–3 composites with different filler arrangements are quantitatively compared to 1–3 composites and to the corresponding bulk material

Structural Analysis and Optimization of a Composite Fan Blade for Future Aircraft Engine

Science.gov (United States)

Coroneos, Rula M.; Gorla, Rama Subba Reddy

2012-09-01

This paper addresses the structural analysis and optimization of a composite sandwich ply lay-up of a NASA baseline solid metallic fan blade comparable to a future Boeing 737 MAX aircraft engine. Sandwich construction with a polymer matrix composite face sheet and honeycomb aluminum core replaces the original baseline solid metallic fan model made of Titanium. The focus of this work is to design the sandwich composite blade with the optimum number of plies for the face sheet that will withstand the combined pressure and centrifugal loads while the constraints are satisfied and the baseline aerodynamic and geometric parameters are maintained. To satisfy the requirements a sandwich construction for the blade is proposed with composite face sheets and a weak core made of honeycomb aluminum material. For aerodynamic considerations, the thickness of the core is optimized where as the overall blade thickness is held fixed in order not to alter the original airfoil geometry. Weight reduction is taken as the objective function by varying the core thickness of the blade within specified upper and lower bounds. Constraints are imposed on radial displacement limitations and ply failure strength. From the optimum design, the minimum number of plies, which will not fail, is back-calculated. The ply lay-up of the blade is adjusted from the calculated number of plies and final structural analysis is performed. Analyses were carried out by utilizing the OpenMDAO Framework, developed at NASA Glenn Research Center combining optimization with structural assessment.

Optimization of the sintering atmosphere for high-density hydroxyapatite–carbon nanotube composites

Science.gov (United States)

White, Ashley A.; Kinloch, Ian A.; Windle, Alan H.; Best, Serena M.

2010-01-01

Hydroxyapatite–carbon nanotube (HA–CNT) composites have the potential for improved mechanical properties over HA for use in bone graft applications. Finding an appropriate sintering atmosphere for this composite presents a dilemma, as HA requires water in the sintering atmosphere to remain phase pure and well hydroxylated, yet CNTs oxidize at the high temperatures required for sintering. The purpose of this study was to optimize the atmosphere for sintering these composites. While the reaction between carbon and water to form carbon monoxide and hydrogen at high temperatures (known as the ‘water–gas reaction’) would seem to present a problem for sintering these composites, Le Chatelier's principle suggests this reaction can be suppressed by increasing the concentration of carbon monoxide and hydrogen relative to the concentration of carbon and water, so as to retain the CNTs and keep the HA's structure intact. Eight sintering atmospheres were investigated, including standard atmospheres (such as air and wet Ar), as well as atmospheres based on the water–gas reaction. It was found that sintering in an atmosphere of carbon monoxide and hydrogen, with a small amount of water added, resulted in an optimal combination of phase purity, hydroxylation, CNT retention and density. PMID:20573629

Experimental Optimization In Polymer BLEND Composite Preparation Based On Mix Level of Taguchi Robust Design

International Nuclear Information System (INIS)

Abdul Aziz Mohamed; Jaafar Abdullah; Dahlan Mohd; Rozaidi Rasid; Megat Harun AlRashid Megat Ahmad; Mahathir Mohamad; Mohd Hamzah Harun

2012-01-01

L 18 orthogonal array in mix level of Taguchi robust design method was carried out to optimize experimental conditions for the preparation of polymer blend composite. Tensile strength and neutron absorption of the composite were the properties of interest. Filler size, filler loading, ball mixing time and dispersion agent concentration were selected as parameters or factors which are expected to affect the composite properties. As a result of Taguchi analysis, filler loading was the most influencing parameter on the tensile strength and neutron absorption. The least influencing was ball-mixing time. The optimal conditions were determined by using mix-level Taguchi robust design method and a polymer composite with tensile strength of 6.33 MPa was successfully prepared. The composite was found to fully absorb thermal neutron flux of 1.04 x 10 5 n/ cm 2 / s with only 2 mm in thickness. In addition, the filler was also characterized by scanning electron microscopy (SEM) and elemental analysis (EDX). (Author)

Optimization of SMA layers in composite structures to enhance damping

Science.gov (United States)

Haghdoust, P.; Cinquemani, S.; Lecis, N.; Bassani, P.

2016-04-01

The performance of lightweight structures can be severely affected by vibration. New design concepts leading to lightweight, slender structural components can increase the vulnerability of the components to failure due to excessive vibration. The intelligent approach to address the problem would be the use of materials which are more capable in dissipating the energy due to their high value of loss factor. Among the different materials available to achieve damping, much attention has been attached to the use of shape memory alloys (SMAs) because of their unique microstructure, leading to good damping capacity. This work describes the design and optimization of a hybrid layered composite structure for the passive suppression of flexural vibrations in slender and light structures. Embedding the SMA layers in composite structure allows to combine different properties: the lightness of the base composite (e.g. fiber glass), the mechanical strength of the insert of metallic material and the relevant damping properties of SMA, in the martensitic phase. In particular, we put our attention on embedding the CuZnAl in the form of thin sheet in a layered composite made by glass fiber reinforced epoxy. By appropriately positioning of the SMA sheets so that they are subjected to the maximum curvature, the damping of the hybrid system can be considerably enhanced. Accordingly analytical method for evaluating the energy dissipation of the thin sheets with different shapes and patterns is developed and is followed by a shape optimization based on genetic algorithm. Eventually different configurations of the hybrid beam structure with different patterns of SMA layer are proposed and compared in the term of damping capacity.

Minimum Compliance Topology Optimization of Shell-Infill Composites for Additive Manufacturing

DEFF Research Database (Denmark)

Wu, Jun; Clausen, Anders; Sigmund, Ole

2017-01-01

Additively manufactured parts are often composed of two sub-structures, a solid shell forming their exterior and a porous infill occupying the interior. To account for this feature this paper presents a novel method for generating simultaneously optimized shell and infill in the context of minimum...... interpolation model into a physical density field, upon which the compliance is minimized. Enhanced by an adapted robust formulation for controlling the minimum length scale of the base, our method generates optimized shell-infill composites suitable for additive manufacturing. We demonstrate the effectiveness...

A systematic approach to determine optimal composition of gel used in radiation therapy

International Nuclear Information System (INIS)

Chang, Yuan-Jen; Hsieh, Bor-Tsung; Liang, Ji-An

2011-01-01

The design of experiment was used to find the optimal composition of N-isopropyl acrylamide (NIPAM) gel. Optical computed tomography was used to scan the polymer gel dosimeter, which was irradiated from 0 to 20 Gy. The study was conducted following a statistical method using a two-level fractional factorial plan involving four variables (gelatin-5% and 6%, NIPAM-3% and 5%, Bis-2.5% and 3%, and THPC-5 and 10 mM). We produced three batches of gels of the same composition to replicate the experiments. Based on the statistical analysis, a regression model was built. The optimal gel composition for the dose range 0-15 Gy with linearity up to 1.000 is as follows: gelatin (5.67%), NIPAM (5%), Bis (2.56%), and THPC (10 mM). The dose response of the NIPAM polymer gel attains stability about 24 h after irradiation and remains stable up to 3 months.

Study and optimization of the carbothermic reduction process for obtaining boron carbide

International Nuclear Information System (INIS)

Castro, A.R.M. de.

1989-01-01

Boron carbide - B sub(4)C - is a ceramic material of technological importance due to its hardness and high chemical and thermal stabilities. Moreover, its high neutron capture cross section makes it suitable for application as neutron absorber in nuclear technology. The process for obtaining carbothermally derived boron carbide has been studied in two steps: firstly, the parameters of the boric acid → boron oxide dehydration reaction have been defined; secondly, the optimization of the carbothermal reduction reaction using boron oxide has been undertaken looking for boron carbide having low level of free carbon. The starting materials as well as the main products have been studied by chemical and spectrographic analyses, X-ray diffractometry, granulometric classification and scanning electron microscopy. The optimization of the carbothermic reduction process allowed for the development and set up of a fabrication procedure yielding high quality B sub(4) C powders, starting from low cost and easily available (in the Brazilian market) raw materials. (author)

Impact of temperature on the biological properties of soil

Science.gov (United States)

Borowik, Agata; Wyszkowska, Jadwiga

2016-01-01

The aim of the study was to determine the response of soil microorganisms and enzymes to the temperature of soil. The effect of the temperatures: 5, 10, 15, 20, and 25°C on the biological properties of soil was investigated under laboratory conditions. The study was performed using four different soils differing in their granulometric composition. It was found that 15°C was the optimal temperature for the development of microorganisms in soil. Typically, in the soil, the highest activity of dehydrogenases was observed at 10-15°C, catalase and acid phosphatase - at 15°C, alkaline phosphatase at 20°C, urease and β-glucosidase at 25°C. The highest colony development index for heterotrophic bacteria was recorded in soils incubated at 25°C, while for actinomycetes and fungi at 15°C. The incubation temperature of soil only slightly changed the ecophysiological variety of the investigated groups of microorganisms. Therefore, the observed climate changes might have a limited impact on the soil microbiological activity, because of the high ability of microorganisms to adopt. The response of soil microorganisms and enzymes was more dependent on the soil granulometric composition, organic carbon, and total nitrogen than on its temperature.

Structural Analysis and Optimization of a Composite Fan Blade for Future Aircraft Engine

Science.gov (United States)

Coroneos, Rula M.

2012-01-01

This report addresses the structural analysis and optimization of a composite fan blade sized for a large aircraft engine. An existing baseline solid metallic fan blade was used as a starting point to develop a hybrid honeycomb sandwich construction with a polymer matrix composite face sheet and honeycomb aluminum core replacing the original baseline solid metallic fan model made of titanium. The focus of this work is to design the sandwich composite blade with the optimum number of plies for the face sheet that will withstand the combined pressure and centrifugal loads while the constraints are satisfied and the baseline aerodynamic and geometric parameters are maintained. To satisfy the requirements, a sandwich construction for the blade is proposed with composite face sheets and a weak core made of honeycomb aluminum material. For aerodynamic considerations, the thickness of the core is optimized whereas the overall blade thickness is held fixed so as to not alter the original airfoil geometry. Weight is taken as the objective function to be minimized by varying the core thickness of the blade within specified upper and lower bounds. Constraints are imposed on radial displacement limitations and ply failure strength. From the optimum design, the minimum number of plies, which will not fail, is back-calculated. The ply lay-up of the blade is adjusted from the calculated number of plies and final structural analysis is performed. Analyses were carried out by utilizing the OpenMDAO Framework, developed at NASA Glenn Research Center combining optimization with structural assessment.

A study on the composition optimization and mechanical properties of Al-Mg-Si cast alloys

International Nuclear Information System (INIS)

Zhang, X.H.; Su, G.C.; Han, Y.Y.; Ai, X.H.; Yan, W.L.

2010-01-01

The mechanical properties of Al-Mg-Si cast alloys with different chemical compositions were investigated using an orthogonal test method. The optimized chemical compositions of Al alloy are given in wt% as follows: 7.0%Si-0.35%Mg-2.0%Cu-0.2%Mn-0.2%Ni-0.1%V-0.8%RE-89.35%Al. The optimized Al-Mg-Si alloy with metal mold casting had excellent mechanical properties. The softening resistance of the optimized alloy was better than that of ZL101 at elevated temperatures. The scanning electron microscopy fractographs of the tensile samples of ZL101 and optimized Al alloy at different magnifications revealed that all the specimens were fractured in a ductile manner, consisting of well-developed dimples over the entire surface. The alloys failed in a mixed-mode fracture, comprised predominantly of transgranular shears and a small amount of quasi-cleavages.

Structural Design Optimization of a Tiltrotor Aircraft Composite Wing to Enhance Whirl Flutter Stability

DEFF Research Database (Denmark)

Kim, Taeseong; Kim, Jaehoon; Shin, Sang Joon

2013-01-01

In order to enhance the aeroelastic stability of a tiltrotor aircraft, a structural optimization framework is developed by applying a multi-level optimization approach. Each optimization level is designed to achieve a different purpose; therefore, relevant optimization schemes are selected for each...... level. Enhancement of the aeroelastic stability is selected as an objective in the upper-level optimization. This is achieved by seeking the optimal structural properties of a composite wing, including its mass, vertical, chordwise, and torsional stiffness. In the upper-level optimization, the response...... surface method (RSM), is selected. On the other hand, lower-level optimization seeks to determine the local detailed cross-sectional parameters, such as the ply orientation angles and ply thickness, which are relevant to the wing structural properties obtained at the upper-level. To avoid manufacturing...

Implementation of Evolution Strategies (ES Algorithm to Optimization Lovebird Feed Composition

Directory of Open Access Journals (Sweden)

Agung Mustika Rizki

2017-05-01

Full Text Available Lovebird current society, especially popular among bird lovers. Some people began to try to develop the cultivation of these birds. In the cultivation process to consider the composition of feed to produce a quality bird. Determining the feed is not easy because it must consider the cost and need for vitamin Lovebird. This problem can be solved by the algorithm Evolution Strategies (ES. Based on test results obtained optimal fitness value of 0.3125 using a population size of 100 and optimal fitness value of 0.3267 in the generation of 1400. 

Optimization of Concrete Composition in Radioactive Waste Management

International Nuclear Information System (INIS)

IIija, P.

1999-01-01

Low and Intermediate level radioactive waste re presents 95% of the total wastes that is conditioned into special concrete containers. Since these containers are to protect radioactive waste safely for about 300 years, the selection and precise control of physical and mechanical characteristics of materials is very important. After volume reduction and valuable components recovery, waste materials have to be conditioned for transport, storage and disposal. Conditioning is the waste management step in which radioactive wastes are immobilized and packed . In this paper methods and optimization of concrete container composition, used for storing radioactive waste, is presented

A numerical investigation on piezoresistive behaviour of carbon nanotube/polymer composites: mechanism and optimizing principle

International Nuclear Information System (INIS)

Wang Zhifeng; Ye Xiongying

2013-01-01

Carbon nanotubes (CNTs) filled polymeric composites can be used as a kind of flexible piezoresistive material in potentially many fields. Due to the diversity of CNTs and polymers, the mechanism and features of their piezoresistive behaviour is still not fully understood. This paper reports our investigations into the mechanism and optimization of piezoresistive CNT/polymer composites. Numerical simulation results showed that the junction resistances between CNTs are a major component of the network conductance of the composite as well as the piezoresistive behaviour. Average junction gap variation (AJGV) was introduced as a quantitative description of the conductance variation of a CNT network caused by strain and the conductance variation of the CNT network was found to be dominated by AJGV. Numerical simulation and analytical results indicated that the key parameters affecting AJGV include the orientation and diameter of CNTs, Poisson’s ratio of the polymer, and the concentration of CNTs in the polymer matrix. An optimizing principle was then given for piezoresistive CNT/polymer composites. (paper)

Method for selection of optimal road safety composite index with examples from DEA and TOPSIS method.

Science.gov (United States)

Rosić, Miroslav; Pešić, Dalibor; Kukić, Dragoslav; Antić, Boris; Božović, Milan

2017-01-01

Concept of composite road safety index is a popular and relatively new concept among road safety experts around the world. As there is a constant need for comparison among different units (countries, municipalities, roads, etc.) there is need to choose an adequate method which will make comparison fair to all compared units. Usually comparisons using one specific indicator (parameter which describes safety or unsafety) can end up with totally different ranking of compared units which is quite complicated for decision maker to determine "real best performers". Need for composite road safety index is becoming dominant since road safety presents a complex system where more and more indicators are constantly being developed to describe it. Among wide variety of models and developed composite indexes, a decision maker can come to even bigger dilemma than choosing one adequate risk measure. As DEA and TOPSIS are well-known mathematical models and have recently been increasingly used for risk evaluation in road safety, we used efficiencies (composite indexes) obtained by different models, based on DEA and TOPSIS, to present PROMETHEE-RS model for selection of optimal method for composite index. Method for selection of optimal composite index is based on three parameters (average correlation, average rank variation and average cluster variation) inserted into a PROMETHEE MCDM method in order to choose the optimal one. The model is tested by comparing 27 police departments in Serbia. Copyright © 2016 Elsevier Ltd. All rights reserved.

Distribution of Artificial Radioisotopes in Granulometric and Organic Fractions of Alluvial Soils Downstream the Krasnoyarsk Mining and Chemical Combine

Energy Technology Data Exchange (ETDEWEB)

Korobova, Elena M.; Linnik, Vitaly G. [Vernadsky Institute of Geochemistry and Analytical Chemistry, 117991, Moscow (Russian Federation); Brown, Justin E. [Norwegian Radiation Protection Authority P.O. Box 55, N-1332 Oesteraas (Norway)

2014-07-01

A study of some artificial radionuclides discharged by the Krasnoyarsk Mining and Chemical Combine (KMCC) in different granulometric and organic fractions of alluvial soils was performed in the near and remote impact zones of the enterprise. Radionuclides were shown to concentrate in fine fractions enriched in hydro-mica and smectites. However in natural conditions the dominating size fraction associated with radionuclide accumulation at the study sites appeared to be made up of silt (0.010 mm) to clay (0.001 mm) sizes. Therefore due to radionuclide sorption and natural aggregation the peaks of a relatively high radionuclide mass accumulation were associated with three granulometric fractions: <0.001 mm, 0.063-0.010 mm and 0.25-0.125 mm. Soil granulometry was shown to reflect specificity of sedimentation at different landscape positions downstream from the KMCC. At the Balchug site a coarser fraction was accumulated close to the channel while finer fractions are deposited at a higher level. The portion of the clay fraction corresponded to the elevation level increasing from the river bank to the terrace. At the Mikhin Island the tendency was different. A coarser fraction was deposited on higher levels while the portion of clay fraction was at a minimum compared to the lower levels. To study the relationship between radionuclide activity concentrations and organic matter content, selected soil samples were subjected to extraction of the humic and fulvic acid fractions with a subsequent determination of radionuclides in the separated phases and the residue component. The air-dry sample was saturated with 0.1 M NaOH, humic acid was precipitated by 1 M HCl at pH=1. The separation resulted in three fractions of the fulvic acids, humic acids, and the residue containing the denuded mineral phase and the refractory organic residue. Radionuclides measured in the first fraction were believed to be the most mobile, those in the second fraction - subjected to the complexation

Material Distribution Optimization for the Shell Aircraft Composite Structure

Science.gov (United States)

Shevtsov, S.; Zhilyaev, I.; Oganesyan, P.; Axenov, V.

2016-09-01

One of the main goal in aircraft structures designing isweight decreasing and stiffness increasing. Composite structures recently became popular in aircraft because of their mechanical properties and wide range of optimization possibilities.Weight distribution and lay-up are keys to creating lightweight stiff strictures. In this paperwe discuss optimization of specific structure that undergoes the non-uniform air pressure at the different flight conditions and reduce a level of noise caused by the airflowinduced vibrations at the constrained weight of the part. Initial model was created with CAD tool Siemens NX, finite element analysis and post processing were performed with COMSOL Multiphysicsr and MATLABr. Numerical solutions of the Reynolds averaged Navier-Stokes (RANS) equations supplemented by k-w turbulence model provide the spatial distributions of air pressure applied to the shell surface. At the formulation of optimization problem the global strain energy calculated within the optimized shell was assumed as the objective. Wall thickness has been changed using parametric approach by an initiation of auxiliary sphere with varied radius and coordinates of the center, which were the design variables. To avoid a local stress concentration, wall thickness increment was defined as smooth function on the shell surface dependent of auxiliary sphere position and size. Our study consists of multiple steps: CAD/CAE transformation of the model, determining wind pressure for different flow angles, optimizing wall thickness distribution for specific flow angles, designing a lay-up for optimal material distribution. The studied structure was improved in terms of maximum and average strain energy at the constrained expense ofweight growth. Developed methods and tools can be applied to wide range of shell-like structures made of multilayered quasi-isotropic laminates.

Optimization of bicelle lipid composition and temperature for EPR spectroscopy of aligned membranes.

Science.gov (United States)

McCaffrey, Jesse E; James, Zachary M; Thomas, David D

2015-01-01

We have optimized the magnetic alignment of phospholipid bilayered micelles (bicelles) for EPR spectroscopy, by varying lipid composition and temperature. Bicelles have been extensively used in NMR spectroscopy for several decades, in order to obtain aligned samples in a near-native membrane environment and take advantage of the intrinsic sensitivity of magnetic resonance to molecular orientation. Recently, bicelles have also seen increasing use in EPR, which offers superior sensitivity and orientational resolution. However, the low magnetic field strength (less than 1 T) of most conventional EPR spectrometers results in homogeneously oriented bicelles only at a temperature well above physiological. To optimize bicelle composition for magnetic alignment at reduced temperature, we prepared bicelles containing varying ratios of saturated (DMPC) and unsaturated (POPC) phospholipids, using EPR spectra of a spin-labeled fatty acid to assess alignment as a function of lipid composition and temperature. Spectral analysis showed that bicelles containing an equimolar mixture of DMPC and POPC homogeneously align at 298 K, 20 K lower than conventional DMPC-only bicelles. It is now possible to perform EPR studies of membrane protein structure and dynamics in well-aligned bicelles at physiological temperatures and below. Copyright © 2014 Elsevier Inc. All rights reserved.

Optimization the composition of sand-lime products modified of diabase aggregate

Science.gov (United States)

Komisarczyk, K.; Stępień, A.

2017-10-01

The problem of optimizing the composition of building materials is currently of great importance due to the increasing competitiveness and technological development in the construction industry. This phenomenon also applies to catalog sand-lime. The respective arrangement of individual components or their equivalents, and linking them with the main parameters of the composition of the mixture, i.e. The lime/sand/water should lead to the intended purpose. The introduction of sand-lime diabase aggregate is concluded with a positive effect of final products. The paper presents the results of optimization with the addition of diabase aggregate. The constant value was the amount of water, variable - the mass of the dry ingredients. The program of experimental studies was taken for 6 series of silicates made in industrial conditions. Final samples were tested for mechanical and physico-chemical expanding the analysis of the mercury intrusion porosimetry, SEM and XRD. The results show that, depending on the aggregate’s contribution, exhibit differences. The sample in an amount of 10% diabase aggregate the compressive strength was higher than in the case of reference sample, while modified samples absorbed less water.

Granular loess classification based

International Nuclear Information System (INIS)

Browzin, B.S.

1985-01-01

This paper discusses how loess might be identified by two index properties: the granulometric composition and the dry unit weight. These two indices are necessary but not always sufficient for identification of loess. On the basis of analyses of samples from three continents, it was concluded that the 0.01-0.5-mm fraction deserves the name loessial fraction. Based on the loessial fraction concept, a granulometric classification of loess is proposed. A triangular chart is used to classify loess

Assessment of various failure theories for weight and cost optimized laminated composites using genetic algorithm

Energy Technology Data Exchange (ETDEWEB)

Goyal, T. [Indian Institute of Technology Kanpur. Dept. of Aerospace Engineering, UP (India); Gupta, R. [Infotech Enterprises Ltd., Hyderabad (India)

2012-07-01

In this work, minimum weight-cost design for laminated composites is presented. A genetic algorithm has been developed for the optimization process. Maximum-Stress, Tsai-Wu and Tsai-Hill failure criteria have been used along with buckling analysis parameter for the margin of safety calculations. The design variables include three materials; namely Carbon-Epoxy, Glass-Epoxy, Kevlar-Epoxy; number of plies; ply orientation angles, varying from -75 deg. to 90 deg. in the intervals of 15 deg. and ply thicknesses which depend on the material in use. The total cost is a sum of material cost and layup cost. Layup cost is a function of the ply angle. Validation studies for solution convergence and weight-cost inverse proportionality are carried out. One set of results for shear loading are also validated from literature for a particular case. A Pareto-Optimal solution set is demonstrated for biaxial loading conditions. It is then extended to applied moments. It is found that global optimum for a given loading condition is a function of the failure criteria for shear loading, with Maximum Stress criteria giving the lightest-cheapest and Tsai-Wu criteria giving the heaviest-costliest optimized laminates. Optimized weight results are plotted from the three criteria to do a comparative study. This work gives a global optimized laminated composite and also a set of other local optimum laminates for a given set of loading conditions. The current algorithm also provides with adequate data to supplement the use of different failure criteria for varying loadings. This work can find use in the industry and/or academia considering the increased use of laminated composites in modern wind blades. (Author)

Global blending optimization of laminated composites with discrete material candidate selection and thickness variation

DEFF Research Database (Denmark)

Sørensen, Søren N.; Stolpe, Mathias

2015-01-01

rate. The capabilities of the method and the effect of active versus inactive manufacturing constraints are demonstrated on several numerical examples of limited size, involving at most 320 binary variables. Most examples are solved to guaranteed global optimality and may constitute benchmark examples...... but is, however, convex in the original mixed binary nested form. Convexity is the foremost important property of optimization problems, and the proposed method can guarantee the global or near-global optimal solution; unlike most topology optimization methods. The material selection is limited...... for popular topology optimization methods and heuristics based on solving sequences of non-convex problems. The results will among others demonstrate that the difficulty of the posed problem is highly dependent upon the composition of the constitutive properties of the material candidates....

The Optimization of the Oiling Bath Cosmetic Composition Containing Rapeseed Phospholipids and Grapeseed Oil by the Full Factorial Design

Directory of Open Access Journals (Sweden)

Michał Górecki

2015-04-01

Full Text Available The proper condition of hydrolipid mantle and the stratum corneum intercellular matrix determines effective protection against transepidermal water loss (TEWL. Some chemicals, improper use of cosmetics, poor hygiene, old age and some diseases causes disorder in the mentioned structures and leads to TEWL increase. The aim of this study was to obtain the optimal formulation composition of an oiling bath cosmetic based on rapeseed phospholipids and vegetable oil with high content of polyunsaturated fatty acids. In this work, the composition of oiling bath form was calculated and the degree of oil dispersion after mixing the bath preparation with water was selected as the objective function in the optimizing procedure. The full factorial design 23 in the study was used. The concentrations of rapeseed lecithin ethanol soluble fraction (LESF, alcohol (E and non-ionic emulsifier (P were optimized. Based on the calculations from our results, the optimal composition of oiling bath cosmetic was: L (LESF 5.0 g, E (anhydrous ethanol 20.0 g and P (Polysorbate 85 1.5 g. The optimization procedure used in the study allowed to obtain the oiling bath cosmetic which gives above 60% higher emulsion dispersion degree 5.001 × 10−5 cm−1 compared to the initial formulation composition with the 3.096 × 10−5 cm−1.

Optimization of composition and technology for tablets containing aspen bark extract

Directory of Open Access Journals (Sweden)

O. I. Onуshkiv

2015-04-01

Full Text Available Summary. Influence of quantitativefactorsof basic quality parameters has been investigated for tabletscontainingextractofaspenbark, receivedbydirect pressingmethodand mathematicalplanningof experiment.To set the optimal composition of tablets containingaspen bark extract the proportion ofProsolv 90, Ludiflash and Polyplasdone XL 10 has been studied. The relationship between the studied factors and parameters of tablets’ regression models has been described. As a result tablets containing aspen bark extractwith mentioned above formula match necessary pharmaco-technological parameters of State Pharmacopoeia of Ukraine. Introduction.Peptic and duodenal ulcer are serious problems in modern medicine. According to statistics this disease is found in 12,83 % of the adult population in Ukraine [1]. Among the remedies for treatment and prevention of peptic ulcers we can find herbal medicines that may be used in the treatment of pre-peptic conditions and during an acute period as a means of adjuvant therapy in combination with strong remedies [2]. An antacid, cytoprotective, anti-inflammatory and reparative actions of aspen bark extract were proved by the researches of domestic and foreign scientists [3, 4]. Previously, we researched the mutual influence of excipients on the main indicators of quality of aspen bark extract tablets obtained by direct compression method. Due to these researches the best excipientshave been selected. It is necessary to establish the optimal quantitative proportion of excipients in order to obtain the tablets with suitable parameters that satisfy the requirements of the State Pharmacopoeia of Ukraine (SPU [5, 6]. Rational selection of excipients requires wide range of studies to obtain the optimal composition of the tablets containing aspen bark extract. Using mathematical planning of the experiment gives the possibility to reduce the number of experiments and to obtain the most detailed results of researches about effects

Optimization of medium composition for the production of compounds effective against Xanthomonas campestris by bacillus subtilis

Directory of Open Access Journals (Sweden)

Rončević Zorana Z.

2014-01-01

Full Text Available The biocontrol agents are a very promising alternative to synthetic pesticides that are presently used to control plant diseases caused by phytopathogenic microorganisms. Members of the Bacillus genera are soil bacteria that produce significant quantities of agriculturally important bioactive compounds. Production of these compounds can be improved by changing the nutritional and environmental conditions. The aim of this study was the optimization of medium composition, using response surface methodology, for the production of compounds effective against Xanthomonas campestris ATCC 13951 by Bacillus subtilis ATCC 6633. To study the production of antimicrobial compounds by selected Bacillus strain, the producing microorganisms were cultivated on nutrient broth. The inhibition zone diameter of 18.0 mm obtained by the diffusion-disc method indicated that the used Bacillus subtilis strain produces compounds with antimicrobial activity against Xanthomonas campestris ATCC 13951. To optimize the composition of the cultivation medium in terms of glycerol, sodium nitrite and phosphates content, experiments were carried out in accordance with Box-Behnken design, and optimization of multiple responses was performed using the concept of desirability function. The developed model predicted that the maximum inhibition zone diameter (26.23 mm against tested phytopathogen is achieved when the initial content of glycerol, sodium nitrite and phosphate were 50.00 g/L, 2.85 g/L and 11.00 g/L, respectively. To minimize the consumption of medium components and costs of effluents processing, additional optimization set was made. The techno-economic analysis of the obtained results has to be done to select optimal medium composition for industrial production of antimicrobial compounds.

Piezoresistive Composite Silicon Dioxide Nanocantilever Surface Stress Sensor: Design and Optimization.

Science.gov (United States)

Mathew, Ribu; Sankar, A Ravi

2018-05-01

In this paper, we present the design and optimization of a rectangular piezoresistive composite silicon dioxide nanocantilever sensor. Unlike the conventional design approach, we perform the sensor optimization by not only considering its electro-mechanical response but also incorporating the impact of self-heating induced thermal drift in its terminal characteristics. Through extensive simulations first we comprehend and quantify the inaccuracies due to self-heating effect induced by the geometrical and intrinsic parameters of the piezoresistor. Then, by optimizing the ratio of electrical sensitivity to thermal sensitivity defined as the sensitivity ratio (υ) we improve the sensor performance and measurement reliability. Results show that to ensure υ ≥ 1, shorter and wider piezoresistors are better. In addition, it is observed that unlike the general belief that high doping concentration of piezoresistor reduces thermal sensitivity in piezoresistive sensors, to ensure υ ≥ 1 doping concentration (p) should be in the range: 1E18 cm-3 ≤ p ≤ 1E19 cm-3. Finally, we provide a set of design guidelines that will help NEMS engineers to optimize the performance of such sensors for chemical and biological sensing applications.

Generalized solution of design optimization and failure analysis of composite drive shaft

Energy Technology Data Exchange (ETDEWEB)

Kollipalli, K.; Shivaramakrishna, K.V.S.; Prabhakaran, R.T.D. [Birla Institute of Technology and Science, Goa (India)

2012-07-01

Composites have an edge over conventional metals like steel and aluminum due to higher stiffness-to-weight ratio and strength-to-weight ratio. Due to these advantages, composites can bring out a revolutionary change in materials used in automotive engineering, as weight savings has positive impacts on other attributes like fuel economy and possible noise, vibration and harshness (NVH). In this paper, the drive line system of an automotive system is targeted for use of composites by keeping constraints in view such as such as torque transmission, torsional buckling load and fundamental natural frequency. Composite drive shafts made of three different composites ('HM Carbon/HS Carbon/E-glass'-epoxy) was modeled using Catia V5R16 CPD workbench and a finite element analysis with boundary conditions, fiber orientation and stacking sequence was performed using ANSYS Composite module. Results obtained were compared to theoretical results and were found to be accurate and in the limits. This paper also speaks on drive shaft modeling and analysis generalization i.e., changes in stacking sequence in the future can be incorporated directly into ANSYS model without modeling it again in Catia. Hence the base model and analysis method made up in this analysis generalization facilitated by CAD/CAE can be used to carry out any composite shaft design optimization process. (Author)

Multi-response parametric optimization in drilling of bamboo/Kevlar fiber reinforced sandwich composite

Science.gov (United States)

Singh, Thingujam Jackson; Samanta, Sutanu

2016-09-01

In the present work an attempt was made towards parametric optimization of drilling bamboo/Kevlar K29 fiber reinforced sandwich composite to minimize the delamination occurred during the drilling process and also to maximize the tensile strength of the drilled composite. The spindle speed and the feed rate of the drilling operation are taken as the input parameters. The influence of these parameters on delamination and tensile strength of the drilled composite studied and analysed using Taguchi GRA and ANOVA technique. The results show that both the response parameters i.e. delamination and tensile strength are more influenced by feed rate than spindle speed. The percentage contribution of feed rate and spindle speed on response parameters are 13.88% and 81.74% respectively.

On the Constitutive Response Characterization for Composite Materials Via Data-Driven Design Optimization

Science.gov (United States)

John G. Michopoulos; John G. Hermanson; Athanasios lliopoulos; Samuel Lambrakos; Tomonari Furukawa

2011-01-01

In the present paper we focus on demonstrating the use of design optimization for the constitutive characterization of anisotropic material systems such as polymer matrix composites, with or without damage. All approaches are based on the availability of experimental data originating from mechatronic material testing systems that can expose specimens to...

Two-step milling on the carbonyl iron particles and optimizing on the composite absorption

Energy Technology Data Exchange (ETDEWEB)

Xu, Yonggang, E-mail: xuyonggang221@163.com [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai 200438 (China); Yuan, Liming; Wang, Xiaobing [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai 200438 (China); Zhang, Deyuan [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

2016-08-15

The flaky carbonyl iron particles (CIPs) were prepared using a two-step milling process. The surface morphology was characterized by the scanning electron microscopy, the static magnetic property was evaluated on a vibrating sample magnetometer and X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The complex permittivity and permeability were measured using a vector network analyzer in the frequency range of 2–18 GHz. Then Hermite interpolation based on the calculated scattering parameters of the tested composite was used to derive the permittivity and permeability of the composite with random volume content. The results showed that the saturation magnetization value of the flaky CIPs decreased as the CIPs was changed to the flakes by high and low speeding milling. The diffraction peaks of the single α-Fe existed in the XRD pattern of CIPs, and the characteristic peaks was broad and the intensity of the diffraction pattern was lower as the high-speeding milling time increased. The sample H2L20 had the largest particle size, the average diameter was 8.64 μm, the thickness was 0.59 μm according to the fitted aspect ratio 14.65. The derived permittivity and permeability using the Hermite interpolation was accurate compared with the tested result, the deviation was about 0.39 + j0.45 and 2.5 + j0.51. Finally, the genetic algorithm was used to optimize the thickness of the CIPs composite of a wide absorbing band of 8–18 GHz. The optimized reflection loss (RL) result showed that the absorbing composites with thickness 1.47 mm had an excellent absorbing property (RL < −10 dB) in 8–18 GHz. - Graphical abstract: The property of absorber added two speeding milling CIPs could be enhanced using the genetic algorithm. - Highlights: • Flaky CIPs were prepared using a two-step milling process. • The permeability increased during the low speeding milling. • The aspect ratio of flaky CIPs increased in the optimized process

Optimizing the milling characteristics of Al-SiC particulate composites

Science.gov (United States)

Karthikeyan, R.; Raghukandan, K.; Naagarazan, R. S.; Pai, B. C.

2000-12-01

The present investigation focuses on the face milling characteristics of LM25Al-SiC particulate composites produced through stir casting. Experiments were conducted according to an L27 orthogonal array and mathematical models were developed for such machining characteristics as flank wear, specific energy and surface roughness whose adequacy was checked. The insignificant effects present in the models were eliminated using a t-test. Goal programming was employed to optimize the cutting conditions by considering such primary objectives as maximizing the metal removal rate and minimizing tool wear, specific energy and surface roughness.

Optimal determination of the elastic constants of woven 2D SiC/SiC composite materials

International Nuclear Information System (INIS)

Mouchtachi, A; Guerjouma, R El; Baboux, J C; Rouby, D; Bouami, D

2004-01-01

For homogeneous materials, the ultrasonic immersion method, associated with a numerical optimization process mostly based on Newton's algorithm, allows the determination of elastic constants for various synthetic and natural composite materials. Nevertheless, a principal limitation of the existing optimization procedure occurs when the considered material is at the limit of the homogeneous hypothesis. Such is the case of the woven bidirectional SiC matrix and SiC fibre composite material. In this study, we have developed two numerical methods for the determination of the elastic constants of the 2D SiC/SiC composite material (2D SiC/SiC). The first one is based on Newton's algorithm: the elastic constants are obtained by minimizing the square deviation between experimental and calculated velocities. The second method is based on the Levenberg-Marquardt algorithm. We show that these algorithms give the same results in the case of homogeneous anisotropic composite materials. For the 2D SiC/SiC composite material, the two methods, using the same measured velocities, give different sets of elastic constants. We then note that the Levenberg-Marquardt algorithm enables a better convergence towards a global set of elastic constants in good agreement with the elastic properties, which can be measured using classical quasi-static methods

Optimization of composite coagulant made from polyferric chloride and tapioca starch in landfill leachate treatment

Science.gov (United States)

Shaylinda, M. Z. N.; Hamidi, A. A.; Mohd, N. A.; Ariffin, A.; Irvan, D.; Hazreek, Z. A. M.; Nizam, Z. M.

2018-04-01

In this research, the performance of polyferric chloride and tapioca flour as composite coagulants for partially stabilized leachate was investigated. Response surface methodology (RSM) was used to optimize the coagulation and flocculation process of partially stabilized leachate. Central composite design a standard design tool in RSM was applied to evaluate the interactions and effects of dose and pH. Dose 0.2 g/L Fe and pH 4.71 were the optimum value suggested by RSM. Experimental test based on the optimum condition, resulted in 95.9%, 94.6% and 50.4% of SS, color and COD removals, respectively. The percentage difference recorded between experimental and model responses was <5%. Therefore, it can be concluded that RSM was an appropriate optimization tool for coagulation and flocculation process.

Optimization of the medium composition for production of antimicrobial substances by bacillus subtilis ATCC 6633

Directory of Open Access Journals (Sweden)

Rončević Zorana Z.

2017-01-01

Full Text Available In the effort to overcome the increase in antimicrobial resistance of different pathogens, natural products from microbial sources appear to be the most favorable alternative to current antibiotics. Production of antimicrobial compounds is highly dependent on the nutritional conditions. Hence, in order to achieve high product yields, selection of the media constituents and optimization of their concentrations are required. In this research, the possibility of antimicrobial substances production using Bacillus subtilis ATCC 6633 was investigated. Also, optimization of the cultivation medium composition in terms of contents of glycerol, sodium nitrite and phosphates was done. Response surface methodology and the method of desirability function were applied for determination of optimal values of the examined factors. The developed model predicts that the maximum inhibition zone diameters for Bacillus cereus ATCC 10876 (33.50 mm and Pseudomonas aeruginosa ATCC 27853 (12.00 mm are achieved when the initial contents of glycerol, sodium nitrite and phosphates were 43.72 g/L, 1.93 g/L and 5.64 g/L, respectively. The results of these experiments suggest that further research should include the utilization of crude glycerol as a carbon source and optimization of composition of such media and cultivation conditions in order to improve production of antimicrobial substances using Bacillus subtilis ATCC 6633.

Plasticizing of YBa2Cu3Ox powders with some organic additions and their effect on superconducting properties of sintered ceramics

International Nuclear Information System (INIS)

Pitov, V.A.; Mozhaev, A.P.; Ludra, M.M.

1992-01-01

Characteristics of compactibility of YBa 2 Cu 3 O x powders of various granulometric compositions with and without plasticizer additions are studied. As plasticizers paraffin and polyvinyl alcohol are used. Pressed pellet density dependence on compacting pressure logarithm is described by the first-order equation. Effect of granulometric composition and plasticizers on equation coefficients is analysed, attain high-quality plasticizing of all powders, but decreases their sintering ability. Use of plasticizers doesn't decrease the initial temperature of transition into superconducting state of sintered samples, but in a number of cases leads to increase of its width, as well as decrease of oxygen index value. These drawbacks may be completely avoided by careful distillation of plasticizers from pressed samples with subsequent sintering

Production and properties of boride powders

International Nuclear Information System (INIS)

Klinskaya, N.A.; Koroleva, E.B.; Petrunichev, V.A.

1990-01-01

Results of plasma metallization of boride powders 40-80 μ diam. are presented. Peculiarities of changes of granulometric powder composition and of metallic cover on refractory cores were investigated. There are shown size- and compositional cores effects on metallization level of poders and on cover structure

Design, fabrication and structural optimization of tubular carbon/Kevlar®/PMMA/graphene nanoplate composite for bone fixation prosthesis.

Science.gov (United States)

Nasiri, F; Ajeli, S; Semnani, D; Jahanshahi, M; Emadi, R

2018-05-02

The present work investigates the mechanical properties of tubular carbon/Kevlar ® composite coated with poly(methyl methacrylate)/graphene nanoplates as used in the internal fixation of bones. Carbon fibers are good candidates for developing high-strength biomaterials and due to better stress transfer and electrical properties, they can enhance tissue formation. In order to improve carbon brittleness, ductile Kevlar ® was added to the composite. The tubular carbon/Kevlar ® composites have been prepared with tailorable braiding technology by changing the fiber pattern and angle in the composite structure and the number of composite layers. Fuzzy analyses are used for optimizing the tailorable parameters of 80 prepared samples and then mechanical properties of selected samples are discussed from the viewpoint of mechanical properties required for a bone fixation device. Experimental results showed that with optimizing braiding parameters the desired composite structure with mechanical properties close to bone properties could be produced. Results showed that carbon/Kevlar ® braid's physical properties, fiber composite distribution and diameter uniformity resulted in matrix uniformity, which enhanced strength and modulus due to better ability for distributing stress on the composite. Finally, as graphene nanoplates demonstrated their potential properties to improve wound healing intended for bone replacement, so reinforcing the PMMA matrix with graphene nanoplates enhanced the composite quality, for use as an implant.

Optimization of process parameters in drilling of fibre hybrid composite using Taguchi and grey relational analysis

Science.gov (United States)

Vijaya Ramnath, B.; Sharavanan, S.; Jeykrishnan, J.

2017-03-01

Nowadays quality plays a vital role in all the products. Hence, the development in manufacturing process focuses on the fabrication of composite with high dimensional accuracy and also incurring low manufacturing cost. In this work, an investigation on machining parameters has been performed on jute-flax hybrid composite. Here, the two important responses characteristics like surface roughness and material removal rate are optimized by employing 3 machining input parameters. The input variables considered are drill bit diameter, spindle speed and feed rate. Machining is done on CNC vertical drilling machine at different levels of drilling parameters. Taguchi’s L16 orthogonal array is used for optimizing individual tool parameters. Analysis Of Variance is used to find the significance of individual parameters. The simultaneous optimization of the process parameters is done by grey relational analysis. The results of this investigation shows that, spindle speed and drill bit diameter have most effect on material removal rate and surface roughness followed by feed rate.

Aglomerante puzolánico formado por cal y ceniza de paja de caña de azúcar: la influencia granulométrica de sus componentes en la actividad aglomerante Pozzolanic binder constituted by lime and cane sugar straw ash: the granulometric influence of its components in the agglomerate activity

Directory of Open Access Journals (Sweden)

Lesday Martínez Fernández

2007-08-01

Full Text Available En el presente trabajo se realiza una caracterización de los componentes de una mezcla binaria formada por cal-ceniza de paja de caña de azúcar mediante las técnicas analíticas de difracción de rayos-x, de análisis químico y granulometric o, valorándose la evolución del proceso de fraguado de esta mezcla binaria, permitiendo dar respuesta a la búsqueda de alternativas como adiciones minerales activas al cemento. Los parámetros estadísticos de las curvas granulométricas de la cal, de la ceniza de la paja de caña y de la mezcla puzolánica (calxeniza = 3:7 brindan criterios del grado de mezclado de los componentes de la mezcla puzolánica y de la utilización de los granos pequeños (The present study carried out a characterization of the components of a binary blend comprised of lime-cane sugar straw ash by means of the analytic techniques ofray-x diffraction, chemical, and granulometric analysis. The evolution of the setting process of this binary blend was assessed, and it appears as an alternative mineral active addition to cement. The statistical parameters of granulometric curves of the lime, the cane straw ash and the pozzolanic blend (lime: ash = 3:7 provide criteria for mixing the blend components fitting the small grains (<9um in the voids formed by bigger grains (45 um. The right size combination can create a space of enhanced reactivity providing compressive strengths of 13 MPa at the age of 28 days

Optimization of tribological behaviour on Al- coconut shell ash composite at elevated temperature

Science.gov (United States)

Siva Sankara Raju, R.; Panigrahi, M. K.; Ganguly, R. I.; Srinivasa Rao, G.

2018-02-01

In this study, determine the tribological behaviour of composite at elevated temperature i.e. 50 - 150 °C. The aluminium matrix composite (AMC) are prepared with compo casting route by volume of reinforcement of coconut shell ash (CSA) such as 5, 10 and 15%. Mechanical properties of composite has enhances with increasing volume of CSA. This study details to optimization of wear behaviour of composite at elevated temperatures. The influencing parameters such as temperature, sliding velocity and sliding distance are considered. The outcome response is wear rate (mm3/m) and coefficient of friction. The experiments are designed based on Taguchi [L9] array. All the experiments are considered as constant load of 10N. Analysis of variance (ANOVA) revealed that temperature is highest influencing factor followed by sliding velocity and sliding distance. Similarly, sliding velocity is most influencing factor followed by temperature and distance on coefficient of friction (COF). Finally, corroborates analytical and regression equation values by confirmation test.

Supercooling suppression of microencapsulated phase change materials by optimizing shell composition and structure

International Nuclear Information System (INIS)

Cao, Fangyu; Yang, Bao

2014-01-01

Highlights: • A new method for supercooling suppression of microPCMs by optimizing the structure of the microcapsule shell. • Large effective latent heat (up to 213 J/g) of the microPCMs, much higher than those using additive as nucleating agents. • Change of shell composition and structure significantly affects the phase transition processes of the encapsulated PCMs. • The latent heat of the shell-induced phase transition is maximized, reaching 83.7% of the latent heat of bulk octadecane. • Hollow spheres with porous rather than solid resin shell are also formed when the SDS concentration is very high. - Abstract: A new method for supercooling suppression of microencapsulated phase change materials (PCMs) has been developed by optimizing the composition and structure of the microcapsule resin shell. The microcapsules comprising paraffin octadecane encapsulated in melamine–formaldehyde resin shell were synthesized with the use the oil-in-water emulsion technique. These PCM microcapsules are 5–15 μm in diameter. The supercooling of these octadecane microcapsules can be as large as 13.6 °C, when the homogeneous nucleation is dominant during the melt crystallization into the thermodynamically stable triclinic phase. It is discovered that the homogeneous nucleation can be mediated by shell-induced nucleation of the triclinic phase and the metastable rotator phase when the shell composition and structure are optimized, without need of any nucleating additives. The effects of synthesis parameters, such as ratio of melamine to formaldehyde, pH of pre-polymer, and pH of emulsion, on the phase transition properties of the octadecane microcapsules have been investigated systemically. The optimum synthesis conditions have been identified in terms of minimizing the supercooling while maintaining heat capacity. Potential applications of this type of phase changeable microcapsules include high heat capacity thermal fluids, thermal management in smart buildings

DMTO – a method for Discrete Material and Thickness Optimization of laminated composite structures

DEFF Research Database (Denmark)

Sørensen, Søren Nørgaard; Sørensen, Rene; Lund, Erik

2014-01-01

This paper presents a gradient based topology optimization method for Discrete Material and Thickness Optimization of laminated composite structures, labelled the DMTOmethod. The capabilities of the proposed method are demonstrated on mass minimization, subject to constraints on the structural...... criteria; buckling load factors, eigenfrequencies, and limited displacements. Furthermore, common design guidelines or rules, referred to as manufacturing constraints, are included explicitly in the optimization problem as series of linear inequalities. The material selection and thickness variation...... to manufacturability. The results will thus give insight into the relation between potential weight saving and design complexity. The results show that the DMTO method is capable of solving the problems robustly with only few intermediate valued design variables....

Optimization of cement composites with the use of fillers from the Chechen Republic fields

Directory of Open Access Journals (Sweden)

Balatkhanova Elita Mahmudovna

Full Text Available The fillers together with binders take part in microstructure formation of matrix basis and contact zones of a composite. The advantage of cement matrix structure with a filler is that inner defects are localized in it - microcracks, macropores and capillary pores, as well as that their quantity, their sizes and stress concentration decrease. Structure formation of filled cement composites is based on the processes taking place in the contact of liquid and stiff phases, which means, it depends on the quantitative relation of the cement, fillers and water, and also dispersivity and physical and chemical activity of the fillers. In the article the authors offer research results of the processes of hydration and physical-mechanical properties of cement composites with fillers from the fields of the Chechen Republic. Research results of heat cement systems are presented, modified by fine fillers. Optimal composition of cement composites filled with powders of quartz, sandstone, river and a mountain limestone of different particle size composition, characterized by a high strength, are obtained.

Analysis of the optimal fuel composition for the Indonesian experimental power reactor

Energy Technology Data Exchange (ETDEWEB)

Liem, Peng Hong [Nippon Advanced Information Service (NAIS Co., Inc.), Ibaraki (Japan); Sembiring, Tagor Malem [National Nuclear Energy Agency of Indonesia, Banten (Indonesia). Center for Nuclear Reactor Technology and Safety; Arbie, Bakri; Subki, Iyos [PT MOTAB Technology, Jakarta Barat (Indonesia)

2017-03-15

The optimal fuel composition of the 10 MWth Experimental Power Reactor (RDE), to be built by the Indonesian National Nuclear Energy Agency (BATAN), is a very important design parameter since it will directly affect the fuel cost, new and spent fuel storage capacity, and other back-end environmental burden. The RDE is a very small sized pebble-bed high temperature gas-cooled reactor (HTGR) with low enriched uranium (LEU) UO{sub 2} TRISO fuel under multipass or once-through-then-out fueling scheme. A scoping study on fuel composition parameters, namely heavy metal (HM) loading per pebble and uranium enrichment is conducted. All burnup, criticality calculations and core equilibrium search are carried out by using BATAN-MPASS, a general in-core fuel management code for pebble bed HTGRs, featured with many automatic equilibrium searching options as well as thermal-hydraulic calculation capability. The RDE User Requirement Document issued by BATAN is used to derive the main core design parameters and constraints. The scoping study is conducted over uranium enrichment in the range of 10 to 20 w/o and HM loading in the range of 4 g to 10 g/pebble. Fissile loading per unit energy generated (kg/GWd) is taken as the objective function for the present scoping study. The analysis results show that the optimal HM loading is around 8 g/pebble. Under the constraint of 80 GWd/t fuel discharge burnup imposed by the technical specification, the uranium enrichment for the optimal HM loading is approximately 13 w/o.

Analysis of the optimal fuel composition for the Indonesian experimental power reactor

International Nuclear Information System (INIS)

Liem, Peng Hong; Sembiring, Tagor Malem

2017-01-01

The optimal fuel composition of the 10 MWth Experimental Power Reactor (RDE), to be built by the Indonesian National Nuclear Energy Agency (BATAN), is a very important design parameter since it will directly affect the fuel cost, new and spent fuel storage capacity, and other back-end environmental burden. The RDE is a very small sized pebble-bed high temperature gas-cooled reactor (HTGR) with low enriched uranium (LEU) UO_2 TRISO fuel under multipass or once-through-then-out fueling scheme. A scoping study on fuel composition parameters, namely heavy metal (HM) loading per pebble and uranium enrichment is conducted. All burnup, criticality calculations and core equilibrium search are carried out by using BATAN-MPASS, a general in-core fuel management code for pebble bed HTGRs, featured with many automatic equilibrium searching options as well as thermal-hydraulic calculation capability. The RDE User Requirement Document issued by BATAN is used to derive the main core design parameters and constraints. The scoping study is conducted over uranium enrichment in the range of 10 to 20 w/o and HM loading in the range of 4 g to 10 g/pebble. Fissile loading per unit energy generated (kg/GWd) is taken as the objective function for the present scoping study. The analysis results show that the optimal HM loading is around 8 g/pebble. Under the constraint of 80 GWd/t fuel discharge burnup imposed by the technical specification, the uranium enrichment for the optimal HM loading is approximately 13 w/o.

Three-dimensional reconstruction of statistically optimal unit cells of polydisperse particulate composites from microtomography

International Nuclear Information System (INIS)

Lee, H.; Brandyberry, M.; Tudor, A.; Matous, K.

2009-01-01

In this paper, we present a systematic approach for characterization and reconstruction of statistically optimal representative unit cells of polydisperse particulate composites. Microtomography is used to gather rich three-dimensional data of a packed glass bead system. First-, second-, and third-order probability functions are used to characterize the morphology of the material, and the parallel augmented simulated annealing algorithm is employed for reconstruction of the statistically equivalent medium. Both the fully resolved probability spectrum and the geometrically exact particle shapes are considered in this study, rendering the optimization problem multidimensional with a highly complex objective function. A ten-phase particulate composite composed of packed glass beads in a cylindrical specimen is investigated, and a unit cell is reconstructed on massively parallel computers. Further, rigorous error analysis of the statistical descriptors (probability functions) is presented and a detailed comparison between statistics of the voxel-derived pack and the representative cell is made.

Multiparameter structural optimization of single-walled carbon nanotube composites: toward record strength, stiffness, and toughness.

Science.gov (United States)

Shim, Bong Sup; Zhu, Jian; Jan, Edward; Critchley, Kevin; Ho, Szushen; Podsiadlo, Paul; Sun, Kai; Kotov, Nicholas A

2009-07-28

Efficient coupling of mechanical properties of SWNTs with the matrix leading to the transfer of unique mechanical properties of SWNTs to the macroscopic composites is a tremendous challenge of today's materials science. The typical mechanical properties of known SWNT composites, such as strength, stiffness, and toughness, are assessed in an introductory survey where we focused on concrete numerical parameters characterizing mechanical properties. Obtaining ideal stress transfer will require fine optimization of nanotube-polymer interface. SWNT nanocomposites were made here by layer-by-layer (LBL) assembly with poly(vinyl alcohol) (PVA), and the first example of optimization in respect to key parameters determining the connectivity at the graphene-polymer interface, namely, degree of SWNT oxidation and cross-linking chemistry, was demonstrated. The resulting SWNT-PVA composites demonstrated tensile strength (σ(ult)) = 504.5 ± 67.3 MPa, stiffness (E) = 15.6 ± 3.8 GPa, and toughness (K) = 121.2 ± 19.2 J/g with maximum values recorded at σ(ult) = 600.1 MPa, E = 20.6 GPa, and K = 152.1 J/g. This represents the strongest and stiffest nonfibrous SWNT composites made to date outperforming other bulk composites by 2-10 times. Its high performance is attributed to both high nanotube content and efficient stress transfer. The resulting LBL composite is also one of the toughest in this category of materials and exceeding the toughness of Kevlar by 3-fold. Our observation suggests that the strengthening and toughening mechanism originates from the synergistic combination of high degree of SWNT exfoliation, efficient SWNT-PVA binding, crack surface roughening, and fairly efficient distribution of local stress over the SWNT network. The need for a multiscale approach in designing SWNT composites is advocated.

Prediction of the granulometric and morphological evolution of a powder in a continuous conversion kiln

International Nuclear Information System (INIS)

Patisson, F.; Hebrard, S.; Ablitzer, D.; Ablitzer-Thouroude, C.; Hebrard, S.

2006-01-01

The UO 2 powder used for the preparation of nuclear fuel pellets is obtained in France by a dry way conversion of gaseous UF 6 . The process includes two steps: hydrolysis into UO 2 F 2 , then reducing pyro-hydrolysis into UO 2 in a continuous conversion kiln. The physical characteristics (morphology, grain size distribution) of the obtained UO 2 powder condition its use properties (sintering ability, casting ability and mechanical strength). A model describing the morphological evolution of the powder in the continuous conversion kiln has been developed in order to dispose of a prediction tool for the morphological characteristics of the UO 2 powder according to its formation conditions. The first part of this work has consisted to model the transport of the powder in the kiln, describing particularly the exchanges between the dense phase (powder bed) and the dispersed phase (rain of particles suspension). One of the originality of the developed model is the taking into account of the role of the raising devices for the calculus of the dynamical variables. The second part has consisted to identify, describe and couple to the preceding dynamical model the phenomena responsible of the morphological and granulometric evolution of the powder in the continuous conversion kiln. A population of fractal agglomerates is considered whose number and size evolve by brownian agglomeration, differential sedimentation agglomeration, pre sintering, fragmentation, and chemical transformations by ex-nucleation and growth. This model uses the formalism of the population balances and the grain size distribution is discretized into sections. The results of the dynamical and morphological calculations are compared to the available measurements. At last is analyzed the respective influence of the different morphological evolution mechanisms on the ended grain size distribution. (O.M.)

Forming of complex-shaped composite tubes using optimized bladder-assisted resin transfer molding

Science.gov (United States)

Schillfahrt, Christian; Fauster, Ewald; Schledjewski, Ralf

2018-05-01

This work addresses the manufacturing of tubular composite structures by means of bladder-assisted resin transfer molding using elastomeric bladders. In order to achieve successful processing of such parts, knowledge of the compaction and impregnation behavior of the textile preform is vital. Hence, efficient analytical models that describe the influencing parameters of the preform compaction and filling stage were developed and verified through practical experiments. A process window describing optimal and critical operating conditions during the injection stage was created by evaluating the impact of the relevant process pressures on filling time. Finally, a cascaded injection procedure was investigated that particularly facilitates the manufacturing of long composite tubes.

Optimization of the composition of the powdered cereal sprouts mixtures

Directory of Open Access Journals (Sweden)

Tumbas-Šaponjac Vesna T.

2016-01-01

Full Text Available Sprouts of cereals have received significant attention as functional food due to their nutritional and functional value. Consumption of sprouts has become increasingly popular among people interested in improving and maintaining their health status by changing dietary habits. Cereal grains contain several classes of phytochemicals, i.e. phenolics, chlorophylls, and carotenoids. However, their nutritional and chemical profile is altered and improved during germination. The purpose of this study was to find the best ratio of the powdered wheat (WS, oat (OS and barley (BS sprouts for designing the cereal sprout mixture (CSM with the highest total phenolic content (TPh and antioxidant capacity (AC, using Simplex-Centroid experimental design and response surface methodology (RSM. Single- and multi-response optimizations showed that OS did not contribute to TPh or AC values of CSM and, therefore, was not included in any of the compositions of the optimized CSM. Single-response optimizations showed that the highest TPh was found for CSM containing 82% BS and 18% WS, while the best AC was found for pure BS. The predicted ratio of cereal sprout powders in CSM obtained by multi-response optimization was: 96% BS and 4% WS. This mixture possessed the highest predicted TPh and AC (372.32 mg GAE/100 g, 549.99 μmol TE/100 g, respectively, which was confirmed to be in accordance with the experimental values. Based on the results obtained in this study, a designed CSM is proposed as a convenient ingredient of functional food products, dietary supplements and nutraceuticals.

Optimization of Cutting Parameters on Delamination of Drilling Glass-Polyester Composites

Directory of Open Access Journals (Sweden)

Majid Habeeb Faidh-Allah

2018-02-01

Full Text Available This paper attempted to study the effect of cutting parameters (spindle speed and feed rate on delamination phenomena during the drilling glass-polyester composites. Drilling process was done by CNC machine with 10 mm diameter of high-speed steel (HSS drill bit. Taguchi technique with L16 orthogonal layout was used to analyze the effective parameters on delamination factor. The optimal experiment was no. 13 with spindle speed 1273 rpm and feed 0.05 mm/rev with minimum delamination factor 1.28.

Spheroidization of transition metal carbides in low temperature plasma

International Nuclear Information System (INIS)

Klinskaya, N.A.; Koroleva, E.B.; Petrunichev, V.A.; Rybalko, O.F.; Solov'ev, P.V.; Ugol'nikova, T.A.

1986-01-01

Plasma process of preparation of titanium, tungsten and chromium carbide spherical powders with the main particle size 40-80 μm is considered. Spheroidization degree, granulometric and phase composition of the product are investigated

Granulometría, morfometría y mineralogía de polvo atmosférico que entra a la cuenca canaria: evidencia de retención de partículas de hierro en la capa de mezcla

OpenAIRE

Jaramillo-Vélez, Alfredo; Menéndez, Inmaculada; Alonso, Ignacio; Mangas, José; Hernández-León, Santiago

2016-01-01

El polvo atmosférico juega un papel importante en el clima y en los procesos oceánicos, particularmente la deposición del polvo sahariano es de suma importancia en la corriente canaria debido a que contiene minerales de hierro que actúan como fertilizante del océano. En este trabajo las partículas de polvo fueron caracterizadas mediante granulometría, morfometría y mineralogía, usando procesamiento de imágenes, microscopia electrónica (SEM-EDS). El polvo analizado en este estudio fue generado...

The theoretical ultimate magnetoelectric coefficients of magnetoelectric composites by optimization design

International Nuclear Information System (INIS)

Wang, H.-L.; Liu, B.

2014-01-01

This paper investigates what is the largest magnetoelectric (ME) coefficient of ME composites, and how to realize it. From the standpoint of energy conservation, a theoretical analysis is carried out on an imaginary lever structure consisting of a magnetostrictive phase, a piezoelectric phase, and a rigid lever. This structure is a generalization of various composite layouts for optimization on ME effect. The predicted theoretical ultimate ME coefficient plays a similar role as the efficiency of ideal heat engine in thermodynamics, and is used to evaluate the existing typical ME layouts, such as the parallel sandwiched layout and the serial layout. These two typical layouts exhibit ME coefficient much lower than the theoretical largest values, because in the general analysis the stress amplification ratio and the volume ratio can be optimized independently and freely, but in typical layouts they are dependent or fixed. To overcome this shortcoming and achieve the theoretical largest ME coefficient, a new design is presented. In addition, it is found that the most commonly used electric field ME coefficient can be designed to be infinitely large. We doubt the validity of this coefficient as a reasonable ME effect index and consider three more ME coefficients, namely the electric charge ME coefficient, the voltage ME coefficient, and the static electric energy ME coefficient. We note that the theoretical ultimate value of the static electric energy ME coefficient is finite and might be a more proper measure of ME effect

Optimization of Ni-Based WC/Co/Cr Composite Coatings Produced by Multilayer Laser Cladding

Directory of Open Access Journals (Sweden)

Andrea Angelastro

2013-01-01

Full Text Available As a surface coating technique, laser cladding (LC has been developed for improving wear, corrosion, and fatigue properties of mechanical components. The main advantage of this process is the capability of introducing hard particles such as SiC, TiC, and WC as reinforcements in the metallic matrix such as Ni-based alloy, Co-based alloy, and Fe-based alloy to form ceramic-metal composite coatings, which have very high hardness and good wear resistance. In this paper, Ni-based alloy (Colmonoy 227-F and Tungsten Carbides/Cobalt/Chromium (WC/Co/Cr composite coatings were fabricated by the multilayer laser cladding technique (MLC. An optimization procedure was implemented to obtain the combination of process parameters that minimizes the porosity and produces good adhesion to a stainless steel substrate. The optimization procedure was worked out with a mathematical model that was supported by an experimental analysis, which studied the shape of the clad track generated by melting coaxially fed powders with a laser. Microstructural and microhardness analysis completed the set of test performed on the coatings.

Multi-objective optimization of the control strategy of electric vehicle electro-hydraulic composite braking system with genetic algorithm

Directory of Open Access Journals (Sweden)

Zhang Fengjiao

2015-03-01

Full Text Available Optimization of the control strategy plays an important role in improving the performance of electric vehicles. In order to improve the braking stability and recover the braking energy, a multi-objective genetic algorithm is applied to optimize the key parameters in the control strategy of electric vehicle electro-hydraulic composite braking system. Various limitations are considered in the optimization process, and the optimization results are verified by a software simulation platform of electric vehicle regenerative braking system in typical brake conditions. The results show that optimization objectives achieved a good astringency, and the optimized control strategy can increase the brake energy recovery effectively under the condition of ensuring the braking stability.

Optimization of fly ash as sand replacement materials (SRM) in cement composites containing coconut fiber

Science.gov (United States)

Nadzri, N. I. M.; Jamaludin, S. B.; Mazlee, M. N.; Jamal, Z. A. Z.

2016-07-01

The need of utilizing industrial and agricultural wastes is very important to maintain sustainability. These wastes are often incorporated with cement composites to improve performances in term of physical and mechanical properties. This study presents the results of the investigation of the response of cement composites containing coconut fiber as reinforcement and fly ash use as substitution of sand at different hardening days. Hardening periods of time (7, 14 and 28 days) were selected to study the properties of cement composites. Optimization result showed that 20 wt. % of fly ash (FA) is a suitable material for sand replacement (SRM). Meanwhile 14 days of hardening period gave highest compressive strength (70.12 MPa) from the cement composite containing 9 wt. % of coconut fiber and fly ash. This strength was comparable with the cement without coconut fiber (74.19 MPa) after 28 days of curing.

UHPC for Blast and Ballistic Protection, Explosion Testing and Composition Optimization

Science.gov (United States)

Bibora, P.; Drdlová, M.; Prachař, V.; Sviták, O.

2017-10-01

The realization of high performance concrete resistant to detonation is the aim and expected outcome of the presented project, which is oriented to development of construction materials for larger objects as protective walls and bunkers. Use of high-strength concrete (HSC / HPC - “high strength / performance concrete”) and high-fiber reinforced concrete (UHPC / UHPFC -“Ultra High Performance Fiber Reinforced Concrete”) seems to be optimal for this purpose of research. The paper describes the research phase of the project, in which we focused on the selection of specific raw materials and chemical additives, including determining the most suitable type and amount of distributed fiber reinforcement. Composition of UHPC was optimized during laboratory manufacture of test specimens to obtain the best desired physical- mechanical properties of developed high performance concretes. In connection with laboratory testing, explosion field tests of UHPC specimens were performed and explosion resistance of laboratory produced UHPC testing boards was investigated.

Fabrication process optimization for improved mechanical properties of Al 7075/SiCp metal matrix composites

Directory of Open Access Journals (Sweden)

Dipti Kanta Das

2016-04-01

Full Text Available Two sets of nine different silicon carbide particulate (SiCp reinforced Al 7075 Metal Matrix Composites (MMCs were fabricated using liquid metallurgy stir casting process. Mean particle size and weight percentage of the reinforcement were varied according to Taguchi L9 Design of Experiments (DOE. One set of the cast composites were then heat treated to T6 condition. Optical micrographs of the MMCs reveal consistent dispersion of reinforcements in the matrix phase. Mechanical properties were determined for both as-cast and heat treated MMCs for comparison of the experimental results. Linear regression models were developed for mechanical properties of the heat treated MMCs using list square method of regression analysis. The fabrication process parameters were then optimized using Taguchi based grey relational analysis for the multiple mechanical properties of the heat treated MMCs. The largest value of mean grey relational grade was obtained for the composite with mean particle size 6.18 µm and 25 weight % of reinforcement. The optimal combination of process parameters were then verified through confirmation experiments, which resulted 42% of improvement in the grey relational grade. Finally, the percentage of contribution of each process parameter on the multiple performance characteristics was calculated through Analysis of Variance (ANOVA.

Process optimization in Nd:YAG laser microdrilling of alumina–aluminium interpenetrating phase composite

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Ranjib Biswas

2015-07-01

Full Text Available In laser beam micromachining process, the quality of the drilled hole is of great importance. The quality of the microdrilled hole mainly depends on appropriate selection of process parameters. Predefined diameter of hole with minimum taper is of today's demand. The composite used for microdrilling operation is alumina–aluminium (Al2O3–Al interpenetrating phase composite (IPC, which is widely used in aircraft and space stations. Until date, no experimental study has been done to obtain microdrilled hole of desired diameter. In the present paper three hole qualities such as hole diameter at entry, at exit and hole taper have been optimized individually as well as simultaneously using a central composite design (CCD based on response surface methodology (RSM during pulsed Nd:YAG laser microdrilling operation on alumina–aluminium IPC sheet of 1.14 mm thickness. The analysis of variance (ANOVA test has also been done to identify the process parameters that contributed the most to get desired hole quality.

OPTIMIZATION OF PLY STACKING SEQUENCE OF COMPOSITE DRIVE SHAFT USING PARTICLE SWARM ALGORITHM

Directory of Open Access Journals (Sweden)

CHANNAKESHAVA K. R.

2011-06-01

Full Text Available In this paper an attempt has been made to optimize ply stacking sequence of single piece E-Glass/Epoxy and Boron /Epoxy composite drive shafts using Particle swarm algorithm (PSA. PSA is a population based evolutionary stochastic optimization technique which is a resent heuristic search method, where mechanics are inspired by swarming or collaborative behavior of biological population. PSA programme is developed to optimize the ply stacking sequence with an objective of weight minimization by considering design constraints as torque transmission capacity, fundamental natural frequency, lateral vibration and torsional buckling strength having number of laminates, ply thickness and stacking sequence as design variables. The weight savings of the E-Glass/epoxy and Boron /Epoxy shaft from PAS were 51% and 85 % of the steel shaft respectively. The optimum results of PSA obtained are compared with results of genetic algorithm (GA results and found that PSA yields better results than GA.

Enhanced Nanotribology and Optimal Self-lubrication in Novel Polymer-Metal Composites

Science.gov (United States)

Seam, Alisha; Brostow, Witold; Olea-Mejia, Oscar

2006-10-01

Cheaper to produce, light-weight polymeric materials with improved micro and nano-scale tribological characteristics ar gradually replacing the heavier metals in gears, cams, ball-bearings, chains, and other critical machine components which operate under high stress, experience substantial sliding friction and wear, and require external lubrication regimes. Application of such high-performance synthetic materials in a whole range of machinery, manufacturing, aerospace and transportation industries would produce far reaching economic, energy conservation and environmental benefits. This paper devises and investigates a novel and previously untested method of developing self-lubricating and wear-resistant polymer based materials (PBMs) by blending a polymer with small proportions of a metallic additive. Tribological experiments establish that as increasing proportions of the metallic additive Iron (Fe) are added to the polymeric base polyethylene (PE), the friction and wear of the resulting composite (PE-Fe) experiences significant decline until an optimal value of 3 to 5 % Iron and then stabilize. Theoretical analysis reveals this phenomenon to likely be a result of the nano-structural formation of a lubricating oxide layer on surface of the polymer-metal composite. Furthermore, the oxide layer prevented significant degradation of the viscoelastic scratch-recovery of the base polymer, even with 10 percent metal additive (Fe) in the composite samples.

A high-throughput reactor system for optimization of Mo–V–Nb mixed oxide catalyst composition in ethane ODH

KAUST Repository

Zhu, Haibo; Laveille, Paco; Rosenfeld, Devon C.; Hedhili, Mohamed N.; Basset, Jean-Marie

2015-01-01

75 Mo-V-Nb mixed oxide catalysts with a broad range of compositions were prepared by a simple evaporation method, and were screened for the ethane oxidative dehydrogenation (ODH) reaction. The compositions of these 75 catalysts were systematically changed by varying the Nb loading, and the Mo/V molar ratio. Characterization by XRD, XPS, H2-TPR and SEM revealed that an intimate structure is formed among the 3 components. The strong interaction among different components leads to the formation of a new phase or an "intimate structure". The dependency of conversion and selectivity on the catalyst composition was clearly demonstrated from the results of high-throughput testing. The optimized Mo-V-Nb molar composition was confirmed to be composed of a Nb content of 4-8%, a Mo content of 70-83%, and a V content of 12-25%. The enhanced catalytic performance of the mixed oxides is obviously due to the synergistic effects of the different components. The optimized compositions for ethane ODH revealed in our high-throughput tests and the structural information provided by our characterization studies can serve as the starting point for future efforts to improve the catalytic performance of Mo-V-Nb oxides. This journal is © The Royal Society of Chemistry.

Spatial distribution and potential biological risk of some metals in relation to granulometric content in core sediments from Chilika Lake, India.

Science.gov (United States)

Barik, Saroja K; Muduli, Pradipta R; Mohanty, Bita; Rath, Prasanta; Samanta, Srikanta

2018-01-01

The article presents first systematic report on the concentration of selected major elements [iron (Fe) and manganese (Mn)] and minor elements [zinc (Zn), copper (Cu), chromium (Cr), lead (Pb), nickel (Ni), and cobalt (Co)] from the core sediment of Chilika Lake, India. The analyzed samples revealed higher content of Pb than the background levels in the entire study area. The extent of contamination from minor and major elements is expressed by assessing (i) the metal enrichments in the sediment through the calculations of anthropogenic factor (AF), pollution load index (PLI), Enrichment factor (EF), and geoaccumulation index (Igeo) and (ii) potential biological risks by the use of sediment quality guidelines like effect range median (ERM) and effect range low (ERL) benchmarks. The estimated indices indicated that sediment is enriched with Pb, Ni, Cr, Cu and Co. The enrichment of these elements seems to be due to the fine granulometric characteristics of the sediment with Fe and Mn oxyhydroxides being the main metal carriers and fishing boats using low grade paints, fuel, and fishing technology using lead beads fixed to fishing nets. Trace element input to the Chilika lake needs to be monitored with due emphasis on Cr and Pb contaminations since the ERM and ERL benchmarks indicated potential biological risk with these metals.

All-automatic swimmer tracking system based on an optimized scaled composite JTC technique

Science.gov (United States)

Benarab, D.; Napoléon, T.; Alfalou, A.; Verney, A.; Hellard, P.

2016-04-01

In this paper, an all-automatic optimized JTC based swimmer tracking system is proposed and evaluated on real video database outcome from national and international swimming competitions (French National Championship, Limoges 2015, FINA World Championships, Barcelona 2013 and Kazan 2015). First, we proposed to calibrate the swimming pool using the DLT algorithm (Direct Linear Transformation). DLT calculates the homography matrix given a sufficient set of correspondence points between pixels and metric coordinates: i.e. DLT takes into account the dimensions of the swimming pool and the type of the swim. Once the swimming pool is calibrated, we extract the lane. Then we apply a motion detection approach to detect globally the swimmer in this lane. Next, we apply our optimized Scaled Composite JTC which consists of creating an adapted input plane that contains the predicted region and the head reference image. This latter is generated using a composite filter of fin images chosen from the database. The dimension of this reference will be scaled according to the ratio between the head's dimension and the width of the swimming lane. Finally, applying the proposed approach improves the performances of our previous tracking method by adding a detection module in order to achieve an all-automatic swimmer tracking system.

Optimization of NiFe2O4/rGO composite electrode for lithium-ion batteries

Science.gov (United States)

Li, Chen; Wang, Xia; Li, Shandong; Li, Qiang; Xu, Jie; Liu, Xiaomin; Liu, Changkun; Xu, Yuanhong; Liu, Jingquan; Li, Hongliang; Guo, Peizhi; Zhao, Xiu Song

2017-09-01

The combination of carbon compositing and the proper choice of binders in one system offer an effective strategy for improving electrode performance for lithium ion batteries (LIBs). Here, we focus on the optimization of reduced graphene oxide content in NiFe2O4/reduced graphene oxide (abbreviated to NiFe2O4/rGO) composites and the proper choice of binders to enhance the cycling stability of the NiFe2O4 electrode. The NiFe2O4/rGO composites were fabricated by a hydrothermal-annealing method, in which the mean size of spinel NiFe2O4 nanoparticles was approximately 20 nm. When tested as anode materials for LIBs, the NiFe2O4/rGO electrodes with carboxymethylcellulose (CMC) binder exhibited excellent lithium-storage performance including high reversible capacity, good cycling durability and high-rate capability. The capacity could be retained as high as 1105 mAh g-1 at a current density of 100 mA g-1 for over 50 cycles, even cycled at higher current density of 1000 mA g-1, a capacity of 800 mAh g-1can be obtained, whereas the electrode with the polyvinylidene fluoride (PVDF) binder suffered from rapid capacity decay under the same test conditions. As a result, the NiFe2O4/rGO composites with CMC binder electrode in this work are promising as anodes for high-performance LIBs, resulting from the synergistic effect of optimal graphene content and proper choice of binder.

Optimization of composite tiltrotor wings with extensions and winglets

Science.gov (United States)

Kambampati, Sandilya

Tiltrotors suffer from an aeroelastic instability during forward flight called whirl flutter. Whirl flutter is caused by the whirling motion of the rotor, characterized by highly coupled wing-rotor-pylon modes of vibration. Whirl flutter is a major obstacle for tiltrotors in achieving high-speed flight. The conventional approach to assure adequate whirl flutter stability margins for tiltrotors is to design the wings with high torsional stiffness, typically using 23% thickness-to-chord ratio wings. However, the large aerodynamic drag associated with these high thickness-to-chord ratio wings decreases aerodynamic efficiency and increases fuel consumption. Wingtip devices such as wing extensions and winglets have the potential to increase the whirl flutter characteristics and the aerodynamic efficiency of a tiltrotor. However, wing-tip devices can add more weight to the aircraft. In this study, multi-objective parametric and optimization methodologies for tiltrotor aircraft with wing extensions and winglets are investigated. The objectives are to maximize aircraft aerodynamic efficiency while minimizing weight penalty due to extensions and winglets, subject to whirl flutter constraints. An aeroelastic model that predicts the whirl flutter speed and a wing structural model that computes strength and weight of a composite wing are developed. An existing aerodynamic model (that predicts the aerodynamic efficiency) is merged with the developed structural and aeroelastic models for the purpose of conducting parametric and optimization studies. The variables of interest are the wing thickness and structural properties, and extension and winglet planform variables. The Bell XV-15 tiltrotor aircraft the chosen as the parent aircraft for this study. Parametric studies reveal that a wing extension of span 25% of the inboard wing increases the whirl flutter speed by 10% and also increases the aircraft aerodynamic efficiency by 8%. Structurally tapering the wing of a tiltrotor

Optimization design and application of composite ultrasonic extraction method for effective constituents of green tea

Directory of Open Access Journals (Sweden)

Cheng-Chi Wang

2015-12-01

Full Text Available A composite ultrasonic process is used to extract five constituent components of green tea, namely caffeine, catechin, epigallocatechin gallate, epicatechin, and chlorogenic acid. The optimal parameters of the extraction process are determined using the robust Taguchi design method. The extracted products are analyzed using gas chromatography and high-performance liquid chromatography. The experimental results confirm the effectiveness of the proposed ultrasonic technique in extracting the components of interest. Moreover, it is shown that the optimal extraction parameters depend on the particular component. In general, the present findings provide a useful reference for further research on the processing of green tea.

Shade guide optimization--a novel shade arrangement principle for both ceramic and composite shade guides when identifying composite test objects.

Science.gov (United States)

Østervemb, Niels; Jørgensen, Jette Nedergaard; Hørsted-Bindslev, Preben

2011-02-01

The most widely used shade guide for composite materials is made of ceramic and arranged according to a non-proven method. There is a need for a composite shade guide using a scientifically based arrangement principle. To compare the shade tab arrangement of the Vitapan Classical shade guide and an individually made composite shade guide using both the originally proposed arrangement principle and arranged according to ΔE2000 values with hue group division. An individual composite shade guide made from Filtek Supreme XT body colors was compared to the Vitapan Classical shade guide. Twenty-five students matched color samples made from Filtek Supreme XT body colors using the two shade guides arranged after the two proposed principles--four shade guides in total. Age, sequence, gender, time, and number of correct matches were recorded. The proposed visually optimal composite shade guide was both fastest and had the highest number of correct matches. Gender was significantly associated with time used for color sampling but not regarding the number of correct shade matches. A composite shade guide is superior compared to the ceramic Vitapan Classical guide when using composite test objects. A rearrangement of the shade guide according to hue, subdivided according to ΔE2000, significantly reduces the time needed to take a color sample and increases the number of correct shade matches. Total color difference in relation to the lightest tab with hue group division is recommended as a possible and universally applicable mode of tab arrangement in dental color standards. Moreover, a shade guide made of the composite materials itself is to be preferred as both a faster and more accurate method of determining color. © 2011, COPYRIGHT THE AUTHORS. JOURNAL COMPILATION © 2011, WILEY PERIODICALS, INC.

About condition of soil ground at locations of the former Azgir nuclear test site

International Nuclear Information System (INIS)

Akhmetov, E.Z.; Adymov, Zh.I.; Ermatov, A.S.

2003-01-01

Full text: Soil condition after underground nuclear explosions at locations of the test sites is considered. The region is situated in the zone of northern deserts and characterized by prevalence of greyish-brown soils in conditions of sharply continental climate and presence of salt in soil-formative complex including tertiary clays, loess-like loam, loam sands and sands. There are small quantity of humus in such soil. During investigation of soil characteristics and ability of soil particles to form conglomerates, possessing of different properties, it is necessary to know both element and phase composition, determining, in the most extent, such physical and mechanical macro-characteristics as: density, stickiness, air and water penetrability, solubility, chemical resistance, granulometric set and others. Phase composition of soil samples can be, to a sufficient extent, determined by the X-ray diffractometry methods using ordinary X-ray experimental facilities. Phase composition of soil includes gypsum, quartz, calcium, potash feldspar hematite, kaolin, peach and mica in different quantities. Data on element composition of soil samples were obtained from the territory of technological locations of test site using the method of X-ray-fluorescent analysis. Granulometric composition of soil ground has been investigated using the methods of dry sieving and wet sieving for determination of radionuclide distribution in different fractions of soil particles. By the method of the dry sieving of soil ground samples there are taken place a sticking the small together of fine fractions and an adhesion of stuck-together particles to more large ones. Therefore, fine fractions cannot be separate completely at dry sieving. As distinct from the dry sieving an use of water jet in the sieving allows to overcome defects of the dry method and, by a sufficiently effective separation of granulometric fractions, to obtain more precise results of investigations of granulometric

Global-Local Analysis and Optimization of a Composite Civil Tilt-Rotor Wing

Science.gov (United States)

Rais-Rohani, Masound

1999-01-01

This report gives highlights of an investigation on the design and optimization of a thin composite wing box structure for a civil tilt-rotor aircraft. Two different concepts are considered for the cantilever wing: (a) a thin monolithic skin design, and (b) a thick sandwich skin design. Each concept is examined with three different skin ply patterns based on various combinations of 0, +/-45, and 90 degree plies. The global-local technique is used in the analysis and optimization of the six design models. The global analysis is based on a finite element model of the wing-pylon configuration while the local analysis uses a uniformly supported plate representing a wing panel. Design allowables include those on vibration frequencies, panel buckling, and material strength. The design optimization problem is formulated as one of minimizing the structural weight subject to strength, stiffness, and d,vnamic constraints. Six different loading conditions based on three different flight modes are considered in the design optimization. The results of this investigation reveal that of all the loading conditions the one corresponding to the rolling pull-out in the airplane mode is the most stringent. Also the frequency constraints are found to drive the skin thickness limits, rendering the buckling constraints inactive. The optimum skin ply pattern for the monolithic skin concept is found to be (((0/+/-45/90/(0/90)(sub 2))(sub s))(sub s), while for the sandwich skin concept the optimal ply pattern is found to be ((0/+/-45/90)(sub 2s))(sub s).

Three-Dimensional Dynamic Topology Optimization with Frequency Constraints Using Composite Exponential Function and ICM Method

Directory of Open Access Journals (Sweden)

Hongling Ye

2015-01-01

Full Text Available The dynamic topology optimization of three-dimensional continuum structures subject to frequency constraints is investigated using Independent Continuous Mapping (ICM design variable fields. The composite exponential function (CEF is selected to be a filter function which recognizes the design variables and to implement the changing process of design variables from “discrete” to “continuous” and back to “discrete.” Explicit formulations of frequency constraints are given based on filter functions, first-order Taylor series expansion. And an improved optimal model is formulated using CEF and the explicit frequency constraints. Dual sequential quadratic programming (DSQP algorithm is used to solve the optimal model. The program is developed on the platform of MSC Patran & Nastran. Finally, numerical examples are given to demonstrate the validity and applicability of the proposed method.

Optimization of fractional composition of the excipient in the elastomeric covering for asphalt highways

Directory of Open Access Journals (Sweden)

E. M. Nurullaev

2013-04-01

Full Text Available The computational method of optimum fractional composition of a dispersible filler of polymeric composite on the basis of three-dimensionally linked elastomer is developed according to non-linear programming. The coefficient of dynamic viscosity of polymeric suspension or the initial module of a viscoelasticity of the join solidification low-molecular rubbers with the final functional groups, filled by many fractional dioxide of silicon are considered as criteria of optimization. Influence of the limiting volume filling on energy of mechanical destruction was investigated. The elastomeric material is offered for use as a covering of asphalt highways in the form of a frost-proof waterproofing layer, which allowing multiply to increase operating properties.

Optimizing the surfactant for the aqueous processing of LiFePO{sub 4} composite electrodes

Energy Technology Data Exchange (ETDEWEB)

Porcher, W.; Jouanneau, S. [Commissariat a l' Energie Atomique, 38054 Grenoble Cedex 9 (France); Lestriez, B.; Guyomard, D. [Institut des Materiaux Jean Rouxel (IMN), Universite de Nantes, CNRS, 44322 Nantes Cedex 3 (France)

2010-05-01

Aqueous processing would reduce the costs associated with the making of the composite electrode. To achieve the incorporation and the dispersion of the carbon black (CB) conductive agent in aqueous slurries, a surfactant is needed. In this paper, three surfactants are compared, an anionic one, the sodium dodecyle sulphate (SDS), a non-ionic one, the isooctylphenylether of polyoxyethylene called commercially Triton X-100 and a cationic one, the hexadecyltrimethylammonium bromide (CTAB), by using rheology and laser granulometry measurements on electrode slurries on one hand, and SEM observations, porosity and adhesion measurements and electrochemical testing on composite electrodes on the other hand. Ionic surfactants were found to be not suitable because a corrosion of the aluminium current collector occurred. The utilization of Triton X-100 favoured a more homogeneous CB distribution, resulted in a better electronic wiring of the active material particles and higher rate behavior of the electrode. Optimal electrochemical performances are obtained for an optimal surfactant concentration which depends on the BET surface area of the CB powder. (author)

The Determination of the Optimal Material Proportion in Natural Fiber-Cement Composites Using Design of Mixture Experiments

OpenAIRE

Aramphongphun Chuckaphun; Ungtawondee Kampanart; Chaysuwan Duangrudee

2016-01-01

This research aims to determine the optimal material proportion in a natural fiber-cement composite as an alternative to an asbestos fibercement composite while the materials cost is minimized and the properties still comply with Thai Industrial Standard (TIS) for applications of profile sheet roof tiles. Two experimental sets were studied in this research. First, a three-component mixture of (i) virgin natural fiber, (ii) synthetic fiber and (iii) cement was studied while the proportion of c...

Multidisciplinary Optimization of Tilt Rotor Blades Using Comprehensive Composite Modeling Technique

Science.gov (United States)

Chattopadhyay, Aditi; McCarthy, Thomas R.; Rajadas, John N.

1997-01-01

An optimization procedure is developed for addressing the design of composite tilt rotor blades. A comprehensive technique, based on a higher-order laminate theory, is developed for the analysis of the thick composite load-carrying sections, modeled as box beams, in the blade. The theory, which is based on a refined displacement field, is a three-dimensional model which approximates the elasticity solution so that the beam cross-sectional properties are not reduced to one-dimensional beam parameters. Both inplane and out-of-plane warping are included automatically in the formulation. The model can accurately capture the transverse shear stresses through the thickness of each wall while satisfying stress free boundary conditions on the inner and outer surfaces of the beam. The aerodynamic loads on the blade are calculated using the classical blade element momentum theory. Analytical expressions for the lift and drag are obtained based on the blade planform with corrections for the high lift capability of rotor blades. The aerodynamic analysis is coupled with the structural model to formulate the complete coupled equations of motion for aeroelastic analyses. Finally, a multidisciplinary optimization procedure is developed to improve the aerodynamic, structural and aeroelastic performance of the tilt rotor aircraft. The objective functions include the figure of merit in hover and the high speed cruise propulsive efficiency. Structural, aerodynamic and aeroelastic stability criteria are imposed as constraints on the problem. The Kreisselmeier-Steinhauser function is used to formulate the multiobjective function problem. The search direction is determined by the Broyden-Fletcher-Goldfarb-Shanno algorithm. The optimum results are compared with the baseline values and show significant improvements in the overall performance of the tilt rotor blade.

Tensile strength changeability of multilayered composites, fabricated through optimized VARTM Technology, an experimental

International Nuclear Information System (INIS)

Nasir, M.A.; Khan, Z.M.

2016-01-01

Life span estimation up to tensile fracture of different fiber reinforced composites, Kevlar Fiber Reinforced Polymer (KFRP) and Glass Fiber Reinforced Polymer (GFRP) along with the strain rate effects on dynamic properties is mainly viewed on experimental basis in this paper. Lab-scale Vacuum Assisted Resin Transfer Molding (VARTM) technique is used to fabricate flawless dog bone specimens considering ASTM standard D638-03 and by using LY5052 resin and HY 5052 hardener. In this research, it is tried to maintain 65% of fiber participation in whole specimen composition matrix. Detail design description of VARTM is also discussed and optimized up to maximum scale to acquire compact, uniformly strengthen and porosity banned standard specimens. A conventional stress-strain curve is established to compare the tensile validity of above mentioned competitive composites. Crack Opening Displacement (COD) of research materials after equal intervals of time is observed; results depict the shear stability and reinforcement perfection of these materials. The crack penetration behavior is examined transversely and longitudinally in this research. (author)

Analysis on and Optimization of a Circular Piezoelectric Composite Laminate for a Micro-Pump Driver

International Nuclear Information System (INIS)

Jia, Jianyuan; Wang, Weidong; Huang, Xinbo

2002-01-01

Among the various micro-pump actuation devices, piezoelectric composite laminate actuation has become an effective method. Due to lacking of analysis treatments, the design of this type micro-pump is in a great limitation. In this paper, an electromechanical-coupled mechanics model is established for the circle-flake micro-actuator. A kind of analysis and design method is presented that piezoelectric plate's radial strain induced by inverse piezoelectric effect is equivalently substituted with transverse stress on piezoelectric composite laminates. It is pointed out that the equivalent transverse load depends on the edge electric field distribution of parallel plate capacitor. The question has been solved that where the neutral plane in the piezoelectric composite laminates lies. Finally, an optimization design is developed on the radius ratio of piezoelectric-to-silicon plate radius by utilizing of FEA modeling

How environmental magnetism can enhance the interpretational value of grain-size analysis: A time-slice study on sediment export to the NW African margin in Heinrich Stadial 1 and Mid Holocene

NARCIS (Netherlands)

Razik, S.; Dekkers, M.J.; Von Dobeneck, T.

2014-01-01

Sediment dynamics in limnic, fluvial and marine environments can be assessed by granulometric and rock-magnetic methodologies. While classical grain-size analysis by sieving or settling mainly bears information on composition and transport, the magnetic mineral assemblages reflect to a larger extent

Simulation Based Optimization of Complex Monolithic Composite Structures Using Cellular Core Technology

Science.gov (United States)

Hickmott, Curtis W.

Cellular core tooling is a new technology which has the capability to manufacture complex integrated monolithic composite structures. This novel tooling method utilizes thermoplastic cellular cores as inner tooling. The semi-rigid nature of the cellular cores makes them convenient for lay-up, and under autoclave temperature and pressure they soften and expand providing uniform compaction on all surfaces including internal features such as ribs and spar tubes. This process has the capability of developing fully optimized aerospace structures by reducing or eliminating assembly using fasteners or bonded joints. The technology is studied in the context of evaluating its capabilities, advantages, and limitations in developing high quality structures. The complex nature of these parts has led to development of a model using the Finite Element Analysis (FEA) software Abaqus and the plug-in COMPRO Common Component Architecture (CCA) provided by Convergent Manufacturing Technologies. This model utilizes a "virtual autoclave" technique to simulate temperature profiles, resin flow paths, and ultimately deformation from residual stress. A model has been developed simulating the temperature profile during curing of composite parts made with the cellular core technology. While modeling of composites has been performed in the past, this project will look to take this existing knowledge and apply it to this new manufacturing method capable of building more complex parts and develop a model designed specifically for building large, complex components with a high degree of accuracy. The model development has been carried out in conjunction with experimental validation. A double box beam structure was chosen for analysis to determine the effects of the technology on internal ribs and joints. Double box beams were manufactured and sectioned into T-joints for characterization. Mechanical behavior of T-joints was performed using the T-joint pull-off test and compared to traditional

Optimization of media composition for Nattokinase production by Bacillus subtilis using response surface methodology.

Science.gov (United States)

Deepak, V; Kalishwaralal, K; Ramkumarpandian, S; Babu, S Venkatesh; Senthilkumar, S R; Sangiliyandi, G

2008-11-01

Response surface methodology and central composite rotary design (CCRD) was employed to optimize a fermentation medium for the production of Nattokinase by Bacillus subtilis at pH 7.5. The four variables involved in this study were Glucose, Peptone, CaCl2, and MgSO4. The statistical analysis of the results showed that, in the range studied; only peptone had a significant effect on Nattokinase production. The optimized medium containing (%) Glucose: 1, Peptone: 5.5, MgSO4: 0.2 and CaCl2: 0.5 resulted in 2-fold increased level of Nattokinase (3194.25U/ml) production compared to initial level (1599.09U/ml) after 10h of fermentation. Nattokinase production was checked with fibrinolytic activity.

Aeroelasticity and structural optimization of composite helicopter rotor blades with swept tips

Science.gov (United States)

Yuan, K. A.; Friedmann, P. P.

1995-01-01

This report describes the development of an aeroelastic analysis capability for composite helicopter rotor blades with straight and swept tips, and its application to the simulation of helicopter vibration reduction through structural optimization. A new aeroelastic model is developed in this study which is suitable for composite rotor blades with swept tips in hover and in forward flight. The hingeless blade is modeled by beam type finite elements. A single finite element is used to model the swept tip. Arbitrary cross-sectional shape, generally anisotropic material behavior, transverse shears and out-of-plane warping are included in the blade model. The nonlinear equations of motion, derived using Hamilton's principle, are based on a moderate deflection theory. Composite blade cross-sectbnal properties are calculated by a separate linear, two-dimensional cross section analysis. The aerodynamic loads are obtained from quasi-steady, incompressible aerodynamics, based on an implicit formulation. The trim and steady state blade aeroelastic response are solved in a fully coupled manner. In forward flight, where the blade equations of motion are periodic, the coupled trim-aeroelastic response solution is obtained from the harmonic balance method. Subsequently, the periodic system is linearized about the steady state response, and its stability is determined from Floquet theory.

Optimized spherical manganese oxide-ferroferric oxide-tin oxide ternary composites as advanced electrode materials for supercapacitors

Science.gov (United States)

Zhu, Jian; Tang, Shaochun; Vongehr, Sascha; Xie, Hao; Meng, Xiangkang

2015-09-01

Inexpensive MnO2 is a promising material for supercapacitors (SCs), but its application is limited by poor electrical conductivity and low specific surface area. We design and fabricate hierarchical MnO2-based ternary composite nanostructures showing superior electrochemical performance via doping with electrochemically active Fe3O4 in the interior and electrically conductive SnO2 nanoparticles in the surface layer. Optimization composition results in a MnO2-Fe3O4-SnO2 composite electrode material with 5.9 wt.% Fe3O4 and 5.3 wt.% SnO2, leading to a high specific areal capacitance of 1.12 F cm-2 at a scan rate of 5 mV s-1. This is two to three times the values for MnO2-based binary nanostructures at the same scan rate. The low amount of SnO2 almost doubles the capacitance of porous MnO2-Fe3O4 (before SnO2 addition), which is attributed to an improved conductivity and remaining porosity. In addition, the optimal ternary composite has a good rate capability and an excellent cycling performance with stable capacitance retention of ˜90% after 5000 charge/discharge cycles at 7.5 mA cm-2. All-solid-state SCs are assembled with such electrodes using polyvinyl alcohol/Na2SO4 electrolyte. An integrated device made by connecting two identical SCs in series can power a light-emitting diode indicator for more than 10 min.

Optimization of wall thickness and lay-up for the shell-like composite structure loaded by non-uniform pressure field

Science.gov (United States)

Shevtsov, S.; Zhilyaev, I.; Oganesyan, P.; Axenov, V.

2017-01-01

The glass/carbon fiber composites are widely used in the design of various aircraft and rotorcraft components such as fairings and cowlings, which have predominantly a shell-like geometry and are made of quasi-isotropic laminates. The main requirements to such the composite parts are the specified mechanical stiffness to withstand the non-uniform air pressure at the different flight conditions and reduce a level of noise caused by the airflow-induced vibrations at the constrained weight of the part. The main objective of present study is the optimization of wall thickness and lay-up of composite shell-like cowling. The present approach assumes conversion of the CAD model of the cowling surface to finite element (FE) representation, then its wind tunnel testing simulation at the different orientation of airflow to find the most stressed mode of flight. Numerical solutions of the Reynolds averaged Navier-Stokes (RANS) equations supplemented by k-w turbulence model provide the spatial distributions of air pressure applied to the shell surface. At the formulation of optimization problem the global strain energy calculated within the optimized shell was assumed as the objective. A wall thickness of the shell had to change over its surface to minimize the objective at the constrained weight. We used a parameterization of the problem that assumes an initiation of auxiliary sphere with varied radius and coordinates of the center, which were the design variables. Curve that formed by the intersection of the shell with sphere defined boundary of area, which should be reinforced by local thickening the shell wall. To eliminate a local stress concentration this increment was defined as the smooth function defined on the shell surface. As a result of structural optimization we obtained the thickness of shell's wall distribution, which then was used to design the draping and lay-up of composite prepreg layers. The global strain energy in the optimized cowling was reduced in2

Optimization of process parameters and catalyst compositions in carbon dioxide oxidative coupling of methane over CaO-MnO/CeO{sub 2} catalyst using response surface methodology

Energy Technology Data Exchange (ETDEWEB)

Istadi,; Amin, Nor Aishah Saidina [Chemical Reaction Engineering Group (CREG), Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, UTM Skudai, Johor Bahru (81310 Malaysia)

2006-05-15

The optimization of process parameters and catalyst compositions for the CO{sub 2} oxidative coupling of methane (CO{sub 2}-OCM) reaction over CaO-MnO/CeO{sub 2} catalyst was developed using Response Surface Methodology (RSM). The relationship between the responses, i.e. CH{sub 4} conversion, C{sub 2} hydrocarbons selectivity or yield, with four independent variables, i.e. CO{sub 2}/CH{sub 4} ratio, reactor temperature, wt.% CaO and wt.% MnO in the catalyst, were presented as empirical mathematical models. The maximum C{sub 2} hydrocarbons selectivity and yields of 82.62% and 3.93%, respectively, were achieved by the individual-response optimization at the corresponding optimal process parameters and catalyst compositions. However, the CH{sub 4} conversion was a saddle function and did not show a unique optimum as revealed by the canonical analysis. Moreover pertaining to simultaneous multi-responses optimization, the maximum C{sub 2} selectivity and yield of 76.56% and 3.74%, respectively, were obtained at a unique optimal process parameters and catalyst compositions. It may be deduced that both individual- and multi-responses optimizations are useful for the recommendation of optimal process parameters and catalyst compositions for the CO{sub 2}-OCM process. (author)

Optimizing Polymer Infusion Process for Thin Ply Textile Composites with Novel Matrix System

Directory of Open Access Journals (Sweden)

Somen K. Bhudolia

2017-03-01

Full Text Available For mass production of structural composites, use of different textile patterns, custom preforming, room temperature cure high performance polymers and simplistic manufacturing approaches are desired. Woven fabrics are widely used for infusion processes owing to their high permeability but their localised mechanical performance is affected due to inherent associated crimps. The current investigation deals with manufacturing low-weight textile carbon non-crimp fabrics (NCFs composites with a room temperature cure epoxy and a novel liquid Methyl methacrylate (MMA thermoplastic matrix, Elium®. Vacuum assisted resin infusion (VARI process is chosen as a cost effective manufacturing technique. Process parameters optimisation is required for thin NCFs due to intrinsic resistance it offers to the polymer flow. Cycles of repetitive manufacturing studies were carried out to optimise the NCF-thermoset (TS and NCF with novel reactive thermoplastic (TP resin. It was noticed that the controlled and optimised usage of flow mesh, vacuum level and flow speed during the resin infusion plays a significant part in deciding the final quality of the fabricated composites. The material selections, the challenges met during the manufacturing and the methods to overcome these are deliberated in this paper. An optimal three stage vacuum technique developed to manufacture the TP and TS composites with high fibre volume and lower void content is established and presented.

Optimizing Polymer Infusion Process for Thin Ply Textile Composites with Novel Matrix System.

Science.gov (United States)

Bhudolia, Somen K; Perrotey, Pavel; Joshi, Sunil C

2017-03-15

For mass production of structural composites, use of different textile patterns, custom preforming, room temperature cure high performance polymers and simplistic manufacturing approaches are desired. Woven fabrics are widely used for infusion processes owing to their high permeability but their localised mechanical performance is affected due to inherent associated crimps. The current investigation deals with manufacturing low-weight textile carbon non-crimp fabrics (NCFs) composites with a room temperature cure epoxy and a novel liquid Methyl methacrylate (MMA) thermoplastic matrix, Elium ® . Vacuum assisted resin infusion (VARI) process is chosen as a cost effective manufacturing technique. Process parameters optimisation is required for thin NCFs due to intrinsic resistance it offers to the polymer flow. Cycles of repetitive manufacturing studies were carried out to optimise the NCF-thermoset (TS) and NCF with novel reactive thermoplastic (TP) resin. It was noticed that the controlled and optimised usage of flow mesh, vacuum level and flow speed during the resin infusion plays a significant part in deciding the final quality of the fabricated composites. The material selections, the challenges met during the manufacturing and the methods to overcome these are deliberated in this paper. An optimal three stage vacuum technique developed to manufacture the TP and TS composites with high fibre volume and lower void content is established and presented.

Optimization of mechanical properties of Al-metal matrix composite produced by direct fusion of beverage cans

International Nuclear Information System (INIS)

Carrasco, C.; Inzunza, G.; Camurri, C.; Rodríguez, C.; Radovic, L.; Soldera, F.; Suarez, S.

2014-01-01

The collection of used beverage cans is limited in countries where they are not fabricated; their low value does not justify the extra charge of exporting them for further processing. To address this increasingly serious problem, here we optimize the properties of an aluminum metal matrix composite (Al-MMC) obtained through direct fusion of beverage cans by using the slag generated in the melting process as reinforcement. This method consists of a modified rheocasting process followed by thixoforming. Our main operational variable is the shear rate applied to a semi-solid bath, subsequent to which a suitable heat treatment (T8) is proposed to improve the mechanical properties. The microstructure, the phases obtained and their effect on composite mechanical properties are analyzed. The composite material produced has, under the best conditions, a yield stress of 175 MPa and a tensile strength of 273 MPa. These results demonstrate that the proposed process does indeed transform the used beverage cans into promising composite materials, e.g., for structural applications

Optimization of mechanical properties of Al-metal matrix composite produced by direct fusion of beverage cans

Energy Technology Data Exchange (ETDEWEB)

Carrasco, C., E-mail: ccarrascoc@udec.cl [Department of Materials Engineering, University of Concepción, Edmundo Larenas 270, Concepción (Chile); Inzunza, G.; Camurri, C.; Rodríguez, C. [Department of Materials Engineering, University of Concepción, Edmundo Larenas 270, Concepción (Chile); Radovic, L. [Department of Chemical Engineering, University of Concepción, Edmundo Larenas 129, Concepción (Chile); Department of Energy and Geo-Environmental Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Soldera, F.; Suarez, S. [Department of Materials Science, Saarland University, Campus D3.3, 66123 Saarbrücken (Germany)

2014-11-03

The collection of used beverage cans is limited in countries where they are not fabricated; their low value does not justify the extra charge of exporting them for further processing. To address this increasingly serious problem, here we optimize the properties of an aluminum metal matrix composite (Al-MMC) obtained through direct fusion of beverage cans by using the slag generated in the melting process as reinforcement. This method consists of a modified rheocasting process followed by thixoforming. Our main operational variable is the shear rate applied to a semi-solid bath, subsequent to which a suitable heat treatment (T8) is proposed to improve the mechanical properties. The microstructure, the phases obtained and their effect on composite mechanical properties are analyzed. The composite material produced has, under the best conditions, a yield stress of 175 MPa and a tensile strength of 273 MPa. These results demonstrate that the proposed process does indeed transform the used beverage cans into promising composite materials, e.g., for structural applications.

Preparation and Optimization of Vanadium Titanomagnetite Carbon Composite Hot Briquette: A New Type of Blast Furnace Burden

Science.gov (United States)

Zhao, W.; Wang, H. T.; Liu, Z. G.; Chu, M. S.; Ying, Z. W.; Tang, J.

2017-10-01

A new type of blast furnace burden, named VTM-CCB (vanadium titanomagnetite carbon composite hot briquette), is proposed and optimized in this paper. The preparation process of VTM-CCB includes two components, hot briquetting and heat treatment. The hot-briquetting and heat-treatment parameters are systematically optimized based on the Taguchi method and single-factor experiment. The optimized preparation parameters of VTM-CCB include a hot-briquetting temperature of 300°C, a coal particle size of coal-added ratio of 28.52%, a heat-treatment temperature of 500°C and a heat-treatment time of 3 h. The compressive strength of VTM-CCB, based on the optimized parameters, reaches 2450 N, which meets the requirement of blast furnace ironmaking. These integrated parameters provide a theoretical basis for the production and application of a blast furnace smelting VTM-CCB.

Optimizing flurbiprofen-loaded NLC by central composite factorial design for ocular delivery

Energy Technology Data Exchange (ETDEWEB)

Gonzalez-Mira, E; Egea, M A; Garcia, M L [Department of Physical Chemistry, Faculty of Pharmacy, Institute of Nanoscience and Nanotechnology, University of Barcelona, Avenida Joan XXIII s/n, E-08028 Barcelona (Spain); Souto, E B [Faculty of Health Sciences, Fernando Pessoa University, Rua Carlos da Maia, Nr. 296, Office S.1, P-4200-150 Porto (Portugal); Calpena, A C, E-mail: eligonzalezmi@ub.edu [Department of Biopharmacy and Pharmaceutical Technology, Faculty of Pharmacy, University of Barcelona, Avenida Joan XXIII s/n, E-08028 Barcelona (Spain)

2011-01-28

The purpose of this study was to design and optimize a new topical delivery system for ocular administration of flurbiprofen (FB), based on lipid nanoparticles. These particles, called nanostructured lipid carriers (NLC), were composed of a fatty acid (stearic acid (SA)) as the solid lipid and a mixture of Miglyol 812 and castor oil (CO) as the liquid lipids, prepared by the hot high pressure homogenization method. After selecting the critical variables influencing the physicochemical characteristics of the NLC (the liquid lipid (i.e. oil) concentration with respect to the total lipid (cOil/L (wt%)), the surfactant and the flurbiprofen concentration, on particle size, polydispersity index and encapsulation efficiency), a three-factor five-level central rotatable composite design was employed to plan and perform the experiments. Morphological examination, crystallinity and stability studies were also performed to accomplish the optimization study. The results showed that increasing cOil/L (wt%) was followed by an enhanced tendency to produce smaller particles, but the liquid to solid lipid proportion should not exceed 30 wt% due to destabilization problems. Therefore, a 70:30 ratio of SA to oil (miglyol + CO) was selected to develop an optimal NLC formulation. The smaller particles obtained when increasing surfactant concentration led to the selection of 3.2 wt% of Tween 80 (non-ionic surfactant). The positive effect of the increase in FB concentration on the encapsulation efficiency (EE) and its total solubilization in the lipid matrix led to the selection of 0.25 wt% of FB in the formulation. The optimal NLC showed an appropriate average size for ophthalmic administration (228.3 nm) with a narrow size distribution (0.156), negatively charged surface (-33.3 mV) and high EE ({approx}90%). The in vitro experiments proved that sustained release FB was achieved using NLC as drug carriers. Optimal NLC formulation did not show toxicity on ocular tissues.

Optimizing flurbiprofen-loaded NLC by central composite factorial design for ocular delivery

International Nuclear Information System (INIS)

Gonzalez-Mira, E; Egea, M A; Garcia, M L; Souto, E B; Calpena, A C

2011-01-01

The purpose of this study was to design and optimize a new topical delivery system for ocular administration of flurbiprofen (FB), based on lipid nanoparticles. These particles, called nanostructured lipid carriers (NLC), were composed of a fatty acid (stearic acid (SA)) as the solid lipid and a mixture of Miglyol 812 and castor oil (CO) as the liquid lipids, prepared by the hot high pressure homogenization method. After selecting the critical variables influencing the physicochemical characteristics of the NLC (the liquid lipid (i.e. oil) concentration with respect to the total lipid (cOil/L (wt%)), the surfactant and the flurbiprofen concentration, on particle size, polydispersity index and encapsulation efficiency), a three-factor five-level central rotatable composite design was employed to plan and perform the experiments. Morphological examination, crystallinity and stability studies were also performed to accomplish the optimization study. The results showed that increasing cOil/L (wt%) was followed by an enhanced tendency to produce smaller particles, but the liquid to solid lipid proportion should not exceed 30 wt% due to destabilization problems. Therefore, a 70:30 ratio of SA to oil (miglyol + CO) was selected to develop an optimal NLC formulation. The smaller particles obtained when increasing surfactant concentration led to the selection of 3.2 wt% of Tween 80 (non-ionic surfactant). The positive effect of the increase in FB concentration on the encapsulation efficiency (EE) and its total solubilization in the lipid matrix led to the selection of 0.25 wt% of FB in the formulation. The optimal NLC showed an appropriate average size for ophthalmic administration (228.3 nm) with a narrow size distribution (0.156), negatively charged surface (-33.3 mV) and high EE (∼90%). The in vitro experiments proved that sustained release FB was achieved using NLC as drug carriers. Optimal NLC formulation did not show toxicity on ocular tissues.

Evaluation of clayey masses compositions starting from the residue incorporation of the red ceramic industry to obtain tubular ceramic membranes; Avaliacao das composicoes de massas argilosas a partir da incorporacao de residuo da industria de ceramica vermelha na obtencao de membranas ceramicas tubulares

Energy Technology Data Exchange (ETDEWEB)

Silva, Adriano Lima da; Chaves, Alexsandra Cristina; Luna, Carlos Bruno Barreto; Neves, Gelmires de Araujo; Lira, Helio de Lucena, E-mail: adrianolimadasilva@hotmail.com, E-mail: alexsandra.chaves@ifap.edu.br, E-mail: brunobarretodemaufcg@hotmail.com, E-mail: gelmires@ufcg.edu.br, E-mail: helio@ufcg.edu.br [Universidade Federal de Campina Grande (UAEMa/CCT/UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais

2017-01-15

The inappropriate residue disposal of red ceramic industry is very high. Nowadays, one of the major challenges is the investigation of processes to obtain alternative materials, enabling the use of these residues to manufacture new materials. This work's objective is to study clayey masses' compositions starting from the residue incorporation of the red ceramic industry to be used in tubular ceramic membranes. Two compositions of ceramic masses were established, composition A (50% of residue) and composition B (70% of residue). Granulometric analysis of the ceramic masses presented an average size of particles, what indicates membranes in the microfiltration scale. Another observed factor is related to the increase of residue amount, what favored a decrease in the ceramic mass' plasticity. A rise in the apparent porosity was also observed, probably because of a possible growing in the bigger pores numbers, due to the sintering high temperature and the elevation of residue quantity itself. (author)

High strength Al–Al2O3p composites: Optimization of extrusion parameters

DEFF Research Database (Denmark)

Luan, B.F.; Hansen, Niels; Godfrey, A.

2011-01-01

Composite aluminium alloys reinforced with Al2O3p particles have been produced by squeeze casting followed by hot extrusion and a precipitation hardening treatment. Good mechanical properties can be achieved, and in this paper we describe an optimization of the key processing parameters...... on an investigation of their mechanical properties and microstructure, as well as on the surface quality of the extruded samples. The evaluation shows that material with good strength, though with limited ductility, can be reliably obtained using a production route of squeeze casting, followed by hot extrusion....... The parameters investigated are the extrusion temperature, the extrusion rate and the extrusion ratio. The materials chosen are AA 2024 and AA 6061, each reinforced with 30vol.% Al2O3 particles of diameter typically in the range from 0.15 to 0.3μm. The extruded composites have been evaluated based...

Thickness filters for gradient based multi-material and thickness optimization of laminated composite structures

DEFF Research Database (Denmark)

Sørensen, Rene; Lund, Erik

2015-01-01

This paper presents a new gradient based method for performing discrete material and thickness optimization of laminated composite structures. The novelty in the new method lies in the application of so-called casting constraints, or thickness filters in this context, to control the thickness...... variation throughout the laminate. The filters replace the layerwise density variables with a single continuous through-the-thickness design variable. Consequently, the filters eliminate the need for having explicit constraints for preventing intermediate void through the thickness of the laminate....... Therefore, the filters reduce both the number of constraints and design variables in the optimization problem. Based upon a continuous approximation of a unit step function, the thickness filters are capable of projecting discrete 0/1 values to the underlying layerwise or ”physical” density variables which...

Structural and compositional optimization of the LiNi0.8Co0.2O2 electrode by new synthesis conditions

International Nuclear Information System (INIS)

Mosqueda L, Y.; Milian P, C. R.; Pomares A, M.; Rodriguez H, J.; Perez C, E.

2012-01-01

The optimization of citrate precursor method to obtain the LiNi 0.8 Co 0.2 O 2 oxide from the thermal decomposition of the citrate precursor (NH 4 ) 3 LiNi 0.8 Co 0.2 (C 6 H 5 O 7 ) is presented. The optimization procedure consists of both the lithium atmosphere and the reaction time control during the decomposition of the citrate precursor. Were obtained and characterized two kind of the (Li l-x Ni x )(Ni 0.8 Co 0.2 )O 2 oxides, with and without optimized synthesis conditions, identified as A and B oxides, respectively. The A and B oxides are characterized by compositional, structural and electrochemical studies. The results showed that is possible to reach the ordered oxide phase at smaller reaction time if the lithium atmosphere is controlled. From the combination of the chemical analysis by Icp and the DRX Rietveld structural refinement it is possible to establish the Li, Ni(II), Ni(III) and Co(III) composition with great accuracy. The resulted structural and compositional transformations have a close relation with technological parameters of the rechargeable lithium battery using Li Ni 0.8 Co 0.2 O 2 oxide as cathode. (Author)

Concretes with ternary composite cements. Part III: multicriteria optimization

Directory of Open Access Journals (Sweden)

Irassar, E. F.

2007-06-01

Full Text Available Optimization methods are tools of vital importance in composite material design, where large numbers of components and design criteria must be taken into account. The formulation of today’s separately milled custommade cements is a clear example of just such a case, for the components must be proportioned to yield mortars and concretes with the proper balance of durability, strength, financial and environmental features. Multicriteria optimization has been used to develop many materials, although its application in cement formulation has yet to be explored. The present paper discusses the use of an objective function to jointly optimize sorptivity and compressive strength in limestone- (up to 20% and/or granulated blast furnace slag- (up to 20% additioned Portland cement concrete.Los métodos de optimización constituyen una herramienta de vital importancia en el diseño de materiales compuestos, donde la cantidad de componentes de la mezcla y los criterios de diseño que deben tenerse en cuenta en el proceso de fabricación son numerosos. En la actualidad, la formulación de un cemento a medida (tailor made a partir del proceso de molienda separada es un claro ejemplo de ello, pues las proporciones relativas de las componentes de la mezcla deben permitir luego obtener morteros y hormigones con el equilibrio justo entre los requerimientos durables, mecánicos, económicos y ecológicos que se soliciten. La optimización por multicriterios ha sido empleada en el desarrollo de diversos materiales, sin embargo, su aplicación en la formulación del cemento no ha sido aún explorada. En este trabajo se presenta la optimización conjunta de la capacidad de absorción y la resistencia a compresión de hormigones elaborados con cemento Portland con caliza (hasta un 20% y/o escoria granulada de alto horno (hasta un 20% utilizando la función objetivo.

Optimization of Blending Parameters and Fiber Size of Kenaf-Bast-Fiber-Reinforced the Thermoplastic Polyurethane Composites by Taguchi Method

Directory of Open Access Journals (Sweden)

Y. A. El-Shekeil

2013-01-01

Full Text Available “Kenaf-fibers- (KF-” reinforced “thermoplastic polyurethane (TPU” composites were prepared by the melt-blending method followed by compression molding. Composite specimens were cut from the sheets that were prepared by compression molding. The criteria of optimization were testing the specimens by tensile test and comparing the ultimate tensile strength. The aim of this study is to optimize processing parameters (e.g., processing temperature, time, and speed and fiber size using the Taguchi approach. These four parameters were investigated in three levels each. The L9 orthogonal array was used based on the number of parameters and levels that has been selected. Furthermore, analysis of variance (ANOVA was used to determine the significance of different parameters. The results showed that the optimum values were 180°C, 50 rpm, 13 min, and 125–300 micron for processing temperature, processing speed, processing time, and fiber size, respectively. Using ANOVA, processing temperature showed the highest significance value followed by fiber size. Processing time and speed did not show any significance on the optimization of TPU/KF.

Multi-Material Design Optimization of Composite Structures

DEFF Research Database (Denmark)

Hvejsel, Christian Frier

properties. The modeling encompasses discrete orientationing of orthotropic materials, selection between different distinct materials as well as removal of material representing holes in the structure within a unified parametrization. The direct generalization of two-phase topology optimization to any number...... of a relaxation-based search heuristic that accelerates a Generalized Benders' Decomposition technique for global optimization and enables the solution of medium-scale problems to global optimality. Improvements in the ability to solve larger problems to global optimality are found and potentially further...... improvements may be obtained with this technique in combination with cheaper heuristics....

Optimization of Composition and Heat Treating of Die Steels for Extended Lifetime; FINAL

International Nuclear Information System (INIS)

David Schwam; John F, Wallace; Quanyou Zhou

2002-01-01

An ''average'' die casting die costs fifty thousand dollars. A die used in making die cast aluminum engine blocks can cost well over one million dollars. These costs provide a strong incentive for extension of die life. While vacuum quenched Premium Grade H13 dies have become the most widely used in the United States, tool makers and die casters are constantly searching for new steels and heat treating procedures to extend die life. This project was undertaken to investigate the effects of composition and heat treating on die life and optimize these parameters

Optimization of friction stir welding process parameters to maximize tensile strength of stir cast AA6061-T6/AlNp composite

International Nuclear Information System (INIS)

Ashok Kumar, B.; Murugan, N.

2014-01-01

Highlights: • AA6061/AlN p cast composite was welded by FSW process. • Regression models were developed to predict UTS and elongation of the FS welded joint. • FS welded joint using the optimized parameters exhibited maximum UTS and joint efficiency. • Defect free weld joint was obtained with optimized parameters value. - Abstract: Aluminium Matrix Composites (AMCs) reinforced with particulate form of reinforcement has replaced monolithic alloys in many engineering industries due to its superior mechanical properties and tailorable thermal and electrical properties. As aluminium nitride (AlN) has high specific strength, high thermal conductivity, high electrical resistivity, low dielectric constant, low coefficient of thermal expansion and good compatibility with aluminium alloy, Al/AlN composite is extensively used in electronic packaging industries. Joining of AMCs is unavoidable in many engineering applications. Friction Stir Welding (FSW) is one of the most suitable welding process to weld the AMCs reinforced with particulate form of ceramics without deteriorating its superior mechanical properties. An attempt has been made to develop regression models to predict the Ultimate Tensile Strength (UTS) and Percent Elongation (PE) of the friction stir welded AA6061 matrix composite reinforced with aluminium nitride particles (AlN p ) by correlating the significant parameters such as tool rotational speed, welding speed, axial force and percentage of AlN p reinforcement in the AA6061 matrix. Statistical software SYSTAT 12 and statistical tools such as analysis of variance (ANOVA) and student’s t test, have been used to validate the developed models. It was observed from the investigation that these factors independently influenced the UTS and PE of the friction stir welded composite joints. The developed regression models were optimized to maximize UTS of friction stir welded AA6061/AlN p composite joints

Process Optimization of Bismaleimide (BMI) Resin Infused Carbon Fiber Composite

Science.gov (United States)

Ehrlich, Joshua W.; Tate, LaNetra C.; Cox, Sarah B.; Taylor, Brian J.; Wright, M. Clara; Caraccio, Anne J.; Sampson, Jeffery W.

2013-01-01

Bismaleimide (BMI) resins are an attractive new addition to world-wide composite applications. This type of thermosetting polyimide provides several unique characteristics such as excellent physical property retention at elevated temperatures and in wet environments, constant electrical properties over a vast array of temperature settings, and nonflammability properties as well. This makes BMI a popular choice in advance composites and electronics applications [I]. Bismaleimide-2 (BMI-2) resin was used to infuse intermediate modulus 7 (IM7) based carbon fiber. Two panel configurations consisting of 4 plies with [+45deg, 90deg]2 and [0deg]4 orientations were fabricated. For tensile testing, a [90deg]4 configuration was tested by rotating the [0deg]4 configirration to lie orthogonal with the load direction of the test fixture. Curing of the BMI-2/IM7 system utilized an optimal infusion process which focused on the integration of the manufacturer-recommended ramp rates,. hold times, and cure temperatures. Completion of the cure cycle for the BMI-2/IM7 composite yielded a product with multiple surface voids determined through visual and metallographic observation. Although the curing cycle was the same for the three panellayups, the surface voids that remained within the material post-cure were different in abundance, shape, and size. For tensile testing, the [0deg]4 layup had a 19.9% and 21.7% greater average tensile strain performance compared to the [90deg]4 and [+45deg, 90deg, 90deg,-45degg] layups, respectively, at failure. For tensile stress performance, the [0deg]4 layup had a 5.8% and 34.0% greater average performance% than the [90deg]4 and [+45deg, 90deg, 90deg,-45deg] layups.

Technique of studying the interaction of charges of explosives

Energy Technology Data Exchange (ETDEWEB)

Yefremov, E.I.; Kravtsov, V.S.; Myachina, N.I.; Rodak, S.N.

1982-01-01

A technique is presented for studying the interaction of explosive charges which includes recording of the velocity of detonation of the studied charges, measurement of mechanical stresses developing in this case in the medium and determination of granulometric composition of the model with simultaneous and diverse initiation.

Analysis of waste coal from the enterprises of Kemerovo region as raw materials for production of ceramic materials

Science.gov (United States)

Stolboushkin, A. Yu; Akst, D. V.; Fomina, O. A.; Ivanov, A. I.; Syromyasov, V. A.

2017-09-01

The analysis of waste coal from mining enterprises of Kemerovo region as raw materials for production of building ceramics is given. The results of studies of material, chemical and mineralogical compositions of waste coal from Abashevskaya processing plant (Novokuznetsk) are presented. It was established that the chemical composition of waste coal refers to aluminosilicate raw materials with a high content of alumina and coloring oxides, the residual carbon content in the wastes is 12-25 %. According to the granulometric composition the waste coal is basically a sandy-dusty fraction with a small amount of clay particles (1-3 %). Additional grinding of coal waste and the introduction of a clay additive in an amount of up to 30 % are recommended. The results of the study of the mineral composition of waste coal are presented. Clay minerals are represented in the descending order by hydromuscovite, montmorillonite and kaolinite, minerals-impurities consist of quartz, feldspar fine-dispersed carbonates. The results of the investigation of ceramic-technological properties of waste coal, which belong to the group of moderately plastic low-melting raw materials, are given. As a result of a comprehensive study it was been established that with chemical, granulometric and mineralogical compositions waste coal with the reduced residual carbon can be used in the production of ceramic bricks.

Interatomic potential to predict the favored and optimized compositions for ternary Cu-Zr-Hf metallic glasses

International Nuclear Information System (INIS)

Luo, S. Y.; Cui, Y. Y.; Dai, Y.; Li, J. H.; Liu, B. X.

2012-01-01

Under the framework of smoothed and long range second-moment approximation of tight-binding, a realistic interatomic potential was first constructed for the Cu-Zr-Hf ternary metal system. Applying the constructed potential, Monte Carlo simulations were carried out to compare the relative stability of crystalline solid solution versus its disordered counterpart over the entire composition triangle of the system (as a function of alloy composition). Simulations not only reveal that the origin of metallic glass formation but also determine, in the composition triangle, a quadrilateral region, within which metallic glass formation is energetically favored. It is proposed to define the energy differences between the crystalline solid solutions and disordered states as the driving force for amorphization and the corresponding calculations pinpoint an optimized composition locating at an composition of Cu 55 Zr 10 Hf 35 , around which the driving force for metallic glass formation reaches its maximum, suggesting that the ternary Cu-Zr-Hf metallic glasses designed to have the compositions around Cu 55 Zr 10 Hf 35 could be more stable than other alloys in the system. Moreover, for the Cu 55 Zr 10 Hf 35 metallic glass, the Voronoi tessellation calculations reveal some interesting features of its atomic configurations and coordination polyhedra distribution.

Evaluation of 2,4-D removal via activated carbon from pomegranate husk/polymer composite hydrogel: Optimization of process parameters through face centered composite design

International Nuclear Information System (INIS)

Taktak, Fulya; Ilbay, Zeynep; Sahin, Selin

2015-01-01

A new type of polymer composite hydrogel was prepared by introducing activated carbons from pomegranate husk into poly ((2-dimethylamino) ethyl methacrylate) network. The removal of 2,4-dichlorophenoxyacetic acid (2,4-D) from aqueous solution was studied with respect to pH of the media, initial 2,4-D concentration and activated carbon content into the polymeric network. Face centered composite design (FCCD) through response surface methodology (RSM) was used for designing the experiments as well as for studying the effects of the process parameters. A quadratic model and a two factor interaction design model were developed for the removal of 2,4-D and adsorption capacity, respectively. The optimum pH of the pesticide solution, activated carbon content into the polymeric network and initial concentration of 2,4-D were found as 3, 2.5 wt% and 100mg/L. 63.245% and 68.805 (mg/g) for the removal of 2,4-D and adsorption capacity were obtained by using Simplex optimization method. Furthermore, the surface characteristics of the adsorbent prepared under optimized conditions were examined by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR).

Evaluation of 2,4-D removal via activated carbon from pomegranate husk/polymer composite hydrogel: Optimization of process parameters through face centered composite design

Energy Technology Data Exchange (ETDEWEB)

Taktak, Fulya; Ilbay, Zeynep [Usak Univ, Usak (Turkmenistan); Sahin, Selin [Istanbul University, Istanbul (Turkmenistan)

2015-09-15

A new type of polymer composite hydrogel was prepared by introducing activated carbons from pomegranate husk into poly ((2-dimethylamino) ethyl methacrylate) network. The removal of 2,4-dichlorophenoxyacetic acid (2,4-D) from aqueous solution was studied with respect to pH of the media, initial 2,4-D concentration and activated carbon content into the polymeric network. Face centered composite design (FCCD) through response surface methodology (RSM) was used for designing the experiments as well as for studying the effects of the process parameters. A quadratic model and a two factor interaction design model were developed for the removal of 2,4-D and adsorption capacity, respectively. The optimum pH of the pesticide solution, activated carbon content into the polymeric network and initial concentration of 2,4-D were found as 3, 2.5 wt% and 100mg/L. 63.245% and 68.805 (mg/g) for the removal of 2,4-D and adsorption capacity were obtained by using Simplex optimization method. Furthermore, the surface characteristics of the adsorbent prepared under optimized conditions were examined by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR).

Root uptake of 137Cs by natural and semi-natural grasses as a function of texture and moisture of soils

International Nuclear Information System (INIS)

Grytsyuk, N.; Arapis, G.; Davydchuk, V.

2006-01-01

This work studies the dependence of 137 Cs root uptake on the structure of landscape, especially on texture and moisture of soils, under natural conditions, on abandoned radiopolluted lands in Northern Ukraine. Researches were carried out on a wide range of landscape conditions, at various levels of 137 Cs contamination (from 20 up to 5000 kBq m -2 ), with different types of soils (approx. 20 soil varieties), which differ in texture, granulometric composition, degrees of gleyization and water regime, and anthropogenic transformation. The results showed that transfer factor (TF) values of 137 Cs differ 50 times for the natural grassy coenoses and 8 times for the semi-natural ones. The lowest 137 Cs TF values were measured in the herbages of dry meadows at automorphous loamy soils, while the highest were observed in wetland meadows at organic soils. Finally, the correlation between 137 Cs TF values and granulometric composition of soil was determined for both automorphic and hydromorphic mineral soils

Morteros aligerados con arcilla expandida: influencia de la granulometría y la adicción de fibras de vidrio ar en el comportamiento mecánico

Directory of Open Access Journals (Sweden)

González Cortina, Mariano

2005-06-01

Full Text Available The study of lightweight cement mortars containing expanded clay aggregate described in this article was conducted to determine the effect of adding fibreglass fibres able to resist the alkalis in cement on the mechanical performance of the mortar. This involved analyzing the following variables: fibre length, degree and effect of dispersion and clay particle size distribution. The lightweight mortars studied are very low density mortars primarily used as fill in different construction situations.En este artículo se presenta un estudio realizado sobre morteros de cemento aligerados con arcilla expandida, para determinar la influencia de la adición de fibras de vidrio resistentes a los álcalis del cemento (AR, en el análisis de las variables: longitud de la fibra, porcentaje e influencia de la dispersabilidad, y la granulometría de la arcilla, sobre el comportamiento mecánico de los mismos. Los morteros aligerados analizados son morteros de muy baja densidad que se están utilizando como material de relleno, fundamentalmente, en distintas soluciones constructivas.

Optimization of strontium adsorption from aqueous solution using (mn-Zr) oxide-pan composite spheres

International Nuclear Information System (INIS)

Inan, S.; Altas, Y.

2009-01-01

The processes based on adsorption and ion exchange have a great role for the pre-concentration and separation of toxic, long lived radionuclides from liquid waste. In Nuclear waste management, the removal of long lived, radiotoxic isotopes from radioactive waste such as strontium reduces the storage problems and facilitates the disposal of the waste. Depending on the waste type, a variety of adsorbents and/or ion exchangers are used. Due to the amorphous structure of hydrous oxides and their mixtures, they don't have reproducible properties. Besides, obtained powders are very fine particles and they can cause operational problems such as pressure drop and filtration. Therefore they are not suitable for column applications. These reasons have recently expedited the study on the preparation of organic-inorganic composite adsorbent beads for industrial applications. PAN, as a stable and porous support for fine particles, provides the utilization of ion exchangers in large scale column applications. The utilization of PAN as a support material with many inorganic ion exchangers was firstly achieved by Sebesta in the beginning of 1990's. Later on, PAN based composite ion exchangers were prepared and used for the removal of radionuclides and heavy metal ions from aqueous solution and waste waters. In this study, spherical (Mn-Zr)oxide-PAN composite were prepared for separation of strontium from aqueous solution in a wide pH range. Sr 2 + adsorption of composite adsorbent was optimized by using experimental design 'Central Composite Design' model.

Microstructural optimization of high temperature SiC/SiC composites by nite process

International Nuclear Information System (INIS)

Shimoda, K.; Park, J.S.; Hinoki, T.; Kohyama, A.

2007-01-01

Full text of publication follows: SiC/SiC composites are one of the promising structural materials for future fusion reactor because of the excellent potentiality in thermal and mechanical properties under very severe environment including high temperature and high energy neutron bombardment. For fusion-grade SiC/SiC composites, high-crystallinity and near-stoichiometric characteristic are required to keep excellent stability against neutron irradiation. The realization of the reactor will be strongly depend on optimization of SiC/SiC composites microstructure, particularly in regard to the materials and processes used for the fiber, interphase and matrix constituents. One of the important accomplishments is the new process, called nano-particle infiltration and transient eutectic phase (NITE) process developed in our group. The microstructure of NITE-SiC/SiC composites, such as fiber volume fraction, porosity and type of pores, can be controlled precisely by the selection of sintering temperature/applied stress history. The objective of this study is to investigate thermal stability and mechanical properties of NITE-SiC/SiC composites at high-temperature. Two kinds of highly-densified SiC/SiC composites with the difference of fiber volume fraction were prepared, and were subjected to exposure tests from 1000 deg. C to 1500 deg. C in an argon-oxygen gas mixture with an oxygen partial pressure of 0.1 Pa. The thermal stability of the composites was characterized through mass change and TEM/SEM observation. The in-situ tensile tests at 1300 deg. C and 1500 deg. C were carried out in the same atmosphere. Most of SiC/SiC composites, even for the advanced CVI-SiC/SiC composites with multi-layered SiC/C inter-phases, underwent reduction in the maximum strength by about 20% at 1300 deg. C. In particular, this reduction was attributed to a slight burnout of the carbon interphase due to oxygen impurities in test atmosphere. However, there was no significant degradation for

Microstructural optimization of high temperature SiC/SiC composites by nite process

Energy Technology Data Exchange (ETDEWEB)

Shimoda, K. [Kyoto Univ., Graduate School of Energy Science (Japan); Park, J.S. [Kyoto Univ., Institute of Advanced Energy (Japan); Hinoki, T.; Kohyama, A. [Kyoto Univ., lnstitute of Advanced Energy, Gokasho, Uji (Japan)

2007-07-01

Full text of publication follows: SiC/SiC composites are one of the promising structural materials for future fusion reactor because of the excellent potentiality in thermal and mechanical properties under very severe environment including high temperature and high energy neutron bombardment. For fusion-grade SiC/SiC composites, high-crystallinity and near-stoichiometric characteristic are required to keep excellent stability against neutron irradiation. The realization of the reactor will be strongly depend on optimization of SiC/SiC composites microstructure, particularly in regard to the materials and processes used for the fiber, interphase and matrix constituents. One of the important accomplishments is the new process, called nano-particle infiltration and transient eutectic phase (NITE) process developed in our group. The microstructure of NITE-SiC/SiC composites, such as fiber volume fraction, porosity and type of pores, can be controlled precisely by the selection of sintering temperature/applied stress history. The objective of this study is to investigate thermal stability and mechanical properties of NITE-SiC/SiC composites at high-temperature. Two kinds of highly-densified SiC/SiC composites with the difference of fiber volume fraction were prepared, and were subjected to exposure tests from 1000 deg. C to 1500 deg. C in an argon-oxygen gas mixture with an oxygen partial pressure of 0.1 Pa. The thermal stability of the composites was characterized through mass change and TEM/SEM observation. The in-situ tensile tests at 1300 deg. C and 1500 deg. C were carried out in the same atmosphere. Most of SiC/SiC composites, even for the advanced CVI-SiC/SiC composites with multi-layered SiC/C inter-phases, underwent reduction in the maximum strength by about 20% at 1300 deg. C. In particular, this reduction was attributed to a slight burnout of the carbon interphase due to oxygen impurities in test atmosphere. However, there was no significant degradation for

Optimization of concrete containers composition in radioactive waste conditioning technology; Optimizacija sastava betona za izradu kontejnera u tehnologiji kondicioniranja radioaktivnih otpadnih materijala

Energy Technology Data Exchange (ETDEWEB)

Mihajlovic, Lj; Plecas, I; Kostadinovic, A [Institut za Nuklearne Nauke Boris Kidric, Belgrade (Yugoslavia)

1984-07-01

In this paper a possibility of optimization of a concrete container composition, used for storing radioactive waste from nuclear power plants, is presented. A mathematical model is given, which permits maximization of the compressive strength and minimization of leakage and permeability. An optimal solution based on experimental data is given. (author)

Foam generation and sample composition optimization for the FOAM-C experiment of the ISS

International Nuclear Information System (INIS)

Carpy, R; Picker, G; Amann, B; Ranebo, H; Vincent-Bonnieu, S; Minster, O; Winter, J; Dettmann, J; Castiglione, L; Höhler, R; Langevin, D

2011-01-01

End of 2009 and early 2010 a sealed cell, for foam generation and observation, has been designed and manufactured at Astrium Friedrichshafen facilities. With the use of this cell, different sample compositions of 'wet foams' have been optimized for mixtures of chemicals such as water, dodecanol, pluronic, aethoxisclerol, glycerol, CTAB, SDS, as well as glass beads. This development is performed in the frame of the breadboarding development activities of the Experiment Container FOAM-C for operation in the ISS Fluid Science Laboratory (ISS). The sample cell supports multiple observation methods such as: Diffusing-Wave and Diffuse Transmission Spectrometry, Time Resolved Correlation Spectroscopy and microscope observation, all of these methods are applied in the cell with a relatively small experiment volume 3 . These units, will be on orbit replaceable sets, that will allow multiple sample compositions processing (in the range of >40).

Optimized design and structural mechanics of a single-piece composite helicopter driveshaft

Science.gov (United States)

Henry, Todd C.

In rotorcraft driveline design, single-piece composite driveshafts have much potential for reducing driveline mass and complexity over multi-segmented metallic driveshafts. The singlepiece shaft concept is enabled by the relatively high fatigue strain capacity of fiber reinforced polymer composites over metals. Challenges for single-piece driveshaft design lie in addressing the self-heating behavior of the composite due to the material damping, as well as, whirling stability, torsional buckling stability, and composite strength. Increased composite temperature due to self-heating reduces the composite strength and is accounted for in this research. The laminate longitudinal stiffness ( Ex) and strength (Fx) are known to be heavily degraded by fiber undulation, however, both are not well understood in compression. The whirling stability (a function of longitudinal stiffness) and the composite strength are strongly influential in driveshaft optimization, and thus are investigated further through the testing of flat and filament wound composite specimens. The design of single-piece composite driveshafts, however, needs to consider many failure criteria, including hysteresis-induced overheating, whirl stability, torsional buckling stability, and material failure by overstress. The present investigation uses multi-objective optimization to investigate the design space which visually highlights design trades. Design variables included stacking sequence, number of laminas, and number of hanger bearings. The design goals were to minimize weight and maximize the lowest factor of safety by adaptively generating solutions to the multi-objective problem. Several design spaces were investigated by examining the effect of misalignment, ambient temperature, and constant power transmission on the optimized solution. Several materials of interest were modeled using experimentally determined elastic properties and novel temperature-dependent composite strength. Compared to the

Fabrication of paper-based analytical devices optimized by central composite design.

Science.gov (United States)

Hamedpour, Vahid; Leardi, Riccardo; Suzuki, Koji; Citterio, Daniel

2018-04-30

In this work, an application of a design of experiments approach for the optimization of an isoniazid assay on a single-area inkjet-printed paper-based analytical device (PAD) is described. For this purpose, a central composite design was used for evaluation of the effect of device geometry and amount of assay reagents on the efficiency of the proposed device. The factors of interest were printed length, width, and sampling volume as factors related to device geometry, and amounts of the assay reagents polyvinyl alcohol (PVA), NH4OH, and AgNO3. Deposition of the assay reagents was performed by a thermal inkjet printer. The colorimetric assay mechanism of this device is based on the chemical interaction of isoniazid, ammonium hydroxide, and PVA with silver ions to induce the formation of yellow silver nanoparticles (AgNPs). The in situ-formed AgNPs can be easily detected by the naked eye or with a simple flat-bed scanner. Under optimal conditions, the calibration curve was linear in the isoniazid concentration range 0.03-10 mmol L-1 with a relative standard deviation of 3.4% (n = 5 for determination of 1.0 mmol L-1). Finally, the application of the proposed device for isoniazid determination in pharmaceutical preparations produced satisfactory results.

Modeling and Optimization of BT and DBT Photooxidation over Multiwall Carbon Nanotube-Titania Composite by Response Surface Methodology

Directory of Open Access Journals (Sweden)

Molood Barmala

2018-01-01

Full Text Available This study investigates optimization of benzothiophene (BT and dibenzothiophene (DBT removal via a photocatalytic process by using central composite design (CCD method. Temperature, pH, and p-25 to MWCNT ratio (g/g in the composite structure are considered as design factors. According to the results, temperature has the greatest impact on removal rate. In optimal condition, after being exposed to UV lamps (9 W for 20 min, 59.8% of the solutions’ BT was removed, while DBT was completely removed. Although the generated structure band gap is 3.4, but due to the presence of MWCNTs in the structure, it is capable of absorbing visible light, and this leads to complete removal of DBT and 42% removal of BT under visible light radiation (in similar circumstances. Kinetics analysis of thiophene’s reaction showed that, in the presence of visible light, first order removal rate constants for DBT and BT are 7.98 and 0.953 1/h, respectively.

Design and evaluation of three-level composite filters obtained by optimizing a compromise average performance measure

Science.gov (United States)

Hendrix, Charles D.; Vijaya Kumar, B. V. K.

1994-06-01

Correlation filters with three transmittance levels (+1, 0, and -1) are of interest in optical pattern recognition because they can be implemented on available spatial light modulators and because the zero level allows us to include a region of support (ROS). The ROS can provide additional control over the filter's noise tolerance and peak sharpness. A new algorithm based on optimizing a compromise average performance measure (CAPM) is proposed for designing three-level composite filters. The performance of this algorithm is compared to other three-level composite filter designs using a common image database and using figures of merit such as the Fisher ratio, error rate, and light efficiency. It is shown that the CAPM algorithm yields better results.

Optimizing flurbiprofen-loaded NLC by central composite factorial design for ocular delivery

Science.gov (United States)

Gonzalez-Mira, E.; Egea, M. A.; Souto, E. B.; Calpena, A. C.; García, M. L.

2011-01-01

The purpose of this study was to design and optimize a new topical delivery system for ocular administration of flurbiprofen (FB), based on lipid nanoparticles. These particles, called nanostructured lipid carriers (NLC), were composed of a fatty acid (stearic acid (SA)) as the solid lipid and a mixture of Miglyol® 812 and castor oil (CO) as the liquid lipids, prepared by the hot high pressure homogenization method. After selecting the critical variables influencing the physicochemical characteristics of the NLC (the liquid lipid (i.e. oil) concentration with respect to the total lipid (cOil/L (wt%)), the surfactant and the flurbiprofen concentration, on particle size, polydispersity index and encapsulation efficiency), a three-factor five-level central rotatable composite design was employed to plan and perform the experiments. Morphological examination, crystallinity and stability studies were also performed to accomplish the optimization study. The results showed that increasing cOil/L (wt%) was followed by an enhanced tendency to produce smaller particles, but the liquid to solid lipid proportion should not exceed 30 wt% due to destabilization problems. Therefore, a 70:30 ratio of SA to oil (miglyol + CO) was selected to develop an optimal NLC formulation. The smaller particles obtained when increasing surfactant concentration led to the selection of 3.2 wt% of Tween® 80 (non-ionic surfactant). The positive effect of the increase in FB concentration on the encapsulation efficiency (EE) and its total solubilization in the lipid matrix led to the selection of 0.25 wt% of FB in the formulation. The optimal NLC showed an appropriate average size for ophthalmic administration (228.3 nm) with a narrow size distribution (0.156), negatively charged surface (-33.3 mV) and high EE (~90%). The in vitro experiments proved that sustained release FB was achieved using NLC as drug carriers. Optimal NLC formulation did not show toxicity on ocular tissues.

Continuous Fiber Ceramic Composites

Energy Technology Data Exchange (ETDEWEB)

Fareed, Ali [Honeywell Advanced Composites Inc. (HACI), Newark, DE (United States); Craig, Phillip A. [Honeywell Advanced Composites Inc. (HACI), Newark, DE (United States)

2002-09-01

Fiber-reinforced ceramic composites demonstrate the high-temperature stability of ceramics--with an increased fracture toughness resulting from the fiber reinforcement of the composite. The material optimization performed under the continuous fiber ceramic composites (CFCC) included a series of systematic optimizations. The overall goals were to define the processing window, to increase the robustinous of the process, to increase process yield while reducing costs, and to define the complexity of parts that could be fabricated.

Optimal QoS-Aware Web Service Composition

NARCIS (Netherlands)

Aiello, Marco; Khoury, Elie el; Lazovik, Alexander; Ratelband, Patrick

2009-01-01

The availability of many independent services on an open network opens the opportunity of composing individual instances to achieve complex functionality. Most often there are several possible compositions to achieve the same high-level functionality; the advantage of choosing one composition

Super-cool paints: optimizing composition with a modified four-flux model

Science.gov (United States)

Gali, Marc A.; Arnold, Matthew D.; Gentle, Angus R.; Smith, Geoffrey B.

2017-09-01

The scope for maximizing the albedo of a painted surface to produce low cost new and retro-fitted super-cool roofing is explored systematically. The aim is easy to apply, low cost paint formulations yielding albedos in the range 0.90 to 0.95. This requires raising the near-infrared (NIR) spectral reflectance into this range, while not reducing the more easily obtained high visible reflectance values. Our modified version of the four-flux method has enabled results on more complex composites. Key parameters to be optimized include; fill factors, particle size and material, using more than one mean size, thickness, substrate and binder materials. The model used is a variation of the classical four-flux method that solves the energy transfer problem through four balance differential equations. We use a different approach to the characteristic parameters to define the absorptance and scattering of the complete composite. This generalization allows extension to inclusion of size dispersion of the pigment particle and various binder resins, including those most commonly in use based on acrylics. Thus, the pigment scattering model has to take account of the matrix having loss in the NIR. A paint ranking index aimed specifically at separating paints with albedo above 0.80 is introduced representing the fraction of time at a sub-ambient temperature.

A modified multi-objective particle swarm optimization approach and its application to the design of a deepwater composite riser

Science.gov (United States)

Zheng, Y.; Chen, J.

2017-09-01

A modified multi-objective particle swarm optimization method is proposed for obtaining Pareto-optimal solutions effectively. Different from traditional multi-objective particle swarm optimization methods, Kriging meta-models and the trapezoid index are introduced and integrated with the traditional one. Kriging meta-models are built to match expensive or black-box functions. By applying Kriging meta-models, function evaluation numbers are decreased and the boundary Pareto-optimal solutions are identified rapidly. For bi-objective optimization problems, the trapezoid index is calculated as the sum of the trapezoid's area formed by the Pareto-optimal solutions and one objective axis. It can serve as a measure whether the Pareto-optimal solutions converge to the Pareto front. Illustrative examples indicate that to obtain Pareto-optimal solutions, the method proposed needs fewer function evaluations than the traditional multi-objective particle swarm optimization method and the non-dominated sorting genetic algorithm II method, and both the accuracy and the computational efficiency are improved. The proposed method is also applied to the design of a deepwater composite riser example in which the structural performances are calculated by numerical analysis. The design aim was to enhance the tension strength and minimize the cost. Under the buckling constraint, the optimal trade-off of tensile strength and material volume is obtained. The results demonstrated that the proposed method can effectively deal with multi-objective optimizations with black-box functions.

Optimal lag in dynamical investments

OpenAIRE

Serva, M.

1998-01-01

A portfolio of different stocks and a risk-less security whose composition is dynamically maintained stable by trading shares at any time step leads to a growth of the capital with a nonrandom rate. This is the key for the theory of optimal-growth investment formulated by Kelly. In presence of transaction costs, the optimal composition changes and, more important, it turns out that the frequency of transactions must be reduced. This simple observation leads to the definition of an optimal lag...

Design Optimization Method for Composite Components Based on Moment Reliability-Sensitivity Criteria

Science.gov (United States)

Sun, Zhigang; Wang, Changxi; Niu, Xuming; Song, Yingdong

2017-08-01

In this paper, a Reliability-Sensitivity Based Design Optimization (RSBDO) methodology for the design of the ceramic matrix composites (CMCs) components has been proposed. A practical and efficient method for reliability analysis and sensitivity analysis of complex components with arbitrary distribution parameters are investigated by using the perturbation method, the respond surface method, the Edgeworth series and the sensitivity analysis approach. The RSBDO methodology is then established by incorporating sensitivity calculation model into RBDO methodology. Finally, the proposed RSBDO methodology is applied to the design of the CMCs components. By comparing with Monte Carlo simulation, the numerical results demonstrate that the proposed methodology provides an accurate, convergent and computationally efficient method for reliability-analysis based finite element modeling engineering practice.

Composition Optimization of Lithium-Based Ternary Alloy Blankets for Fusion Reactors

Science.gov (United States)

Jolodosky, Alejandra

any quantity of interest. This allows multiple responses to be calculated by perturbing the input parameter without having to directly perform separate calculations. The approach is strictly created for critical systems, but was utilized as the basis of a new methodology implemented for fixed source problems, known as Exact Perturbation Theory (EPT). EPT can calculate the tritium breeding ratio response, caused by a perturbation in the composition of the ternary alloy. The downfall of EPT methodology is that it cannot account for the collision history at large perturbations and thus, produces results with high uncertainties. Preliminary analysis for EPT with Serpent for a LiPbBa alloy demonstrated that 25 simulations per ternary must be completed so that most uncertainties calculated at large perturbations do not exceed 0.05. To reduce the uncertainties of the results, generalized least squares (GSL) method was implemented, to replace imprecise TBR results with more accurate ones. It was demonstrated that a combination of EPT Serpent calculations with the application of GLS for results with high uncertainties is the most effective and produces values with the highest fidelity. The scheme finds an alloy composition that has a TBR within a range of interest, while imposing constraint on the EMF, and a requirement to minimize lithium concentration. It involved a three-level iteration process with each level zooming in closer on the area of interest to fine tune the correct composition. Both alloys studied, LiPbBa and LiSnZn, had optimized compositions close to the leftmost edge of the ternary, increasing the complexity of optimization due to the highly uncertain results found in these regions. Additional GPT methodologies were considered for optimization studies, specifically with the use of deterministic codes. Currently, an optimization deterministic code, SMORES, is available in the SCALE code package, but only for critical systems. Subsequently, it was desired to

Optimization of process parameters for spark plasma sintering of nano structured SAF 2205 composite

Directory of Open Access Journals (Sweden)

Samuel Ranti Oke

2018-04-01

Full Text Available This research optimized spark plasma sintering (SPS process parameters in terms of sintering temperature, holding time and heating rate for the development of a nano-structured duplex stainless steel (SAF 2205 grade reinforced with titanium nitride (TiN. The mixed powders were sintered using an automated spark plasma sintering machine (model HHPD-25, FCT GmbH, Germany. Characterization was performed using X-ray diffraction and scanning electron microscopy. Density and hardness of the composites were investigated. The XRD result showed the formation of FeN0.068. SEM/EDS revealed the presence of nano ranged particles of TiN segregated at the grain boundaries of the duplex matrix. A decrease in hardness and densification was observed when sintering temperature and heating rate were 1200 °C and 150 °C/min respectively. The optimum properties were obtained in composites sintered at 1150 °C for 15 min and 100 °C/min. The composite grades irrespective of the process parameters exhibited similar shrinkage behavior, which is characterized by three distinctive peaks, which is an indication of good densification phenomena. Keywords: Spark plasma sintering, Duplex stainless steel (SAF 2205, Titanium nitride (TiN, Microstructure, Density, Hardness

Optimization of Microencapsulation Composition of Menthol, Vanillin, and Benzyl Acetate inside Polyvinyl Alcohol with Coacervation Method for Application in Perfumery

Science.gov (United States)

Sahlan, Muhamad; Raihani Rahman, Mohammad

2017-07-01

One of many applications of essential oils is as fragrance in perfumery. Menthol, benzyl acetate, and vanillin, each represents olfactive characteristic of peppermint leaves, jasmine flowers, and vanilla beans, are commonly used in perfumery. These components are highly volatile, hence the fragrance components will quickly evaporate resulting in short-lasting scent and low shelf life. In this research, said components have been successfully encapsulated simultaneously inside Polyvinyl Alcohol (PVA) using simple coacervation method to increase its shelf life. Optimization has been done using Central Composite Diagram with 4 independent variables, i.e. composition of menthol, benzyl acetate, vanillin, and tergitol 15-S-9 (as emulsifier). Encapsulation efficiency, loading capacity, and microcapsule size have been measured. In optimized composition of menthol (13.98 %w/w), benzyl acetate (14.75 %w/w), vanillin (17.84 %w/w), and tergitol 15-S-9 (13.4 %w/w) encapsulation efficiency of 97,34% and loading capacity of 46,46% have been achieved. Mean diameter of microcapsule is 20,24 μm and within range of 2,011-36,24 μm. Final product was achieved in the form of cross linked polyvinyl alcohol with hydrogel consistency and orange to yellow in color.

Optimization of sensor introduction into laminated composite materials

Science.gov (United States)

Schaaf, Kristin; Nemat-Nasser, Sia

2008-03-01

This work seeks to extend the functionality of the composite material beyond that of simply load-bearing and to enable in situ sensing, without compromising the structural integrity of the host composite material. Essential to the application of smart composites is the issue of the mechanical coupling of the sensor to the host material. Here we present various methods of embedding sensors within the host composite material. In this study, quasi-static three-point bending (short beam) and fatigue three-point bending (short beam) tests are conducted in order to characterize the effects of introducing the sensors into the host composite material. The sensors that are examined include three types of polyvinylidene fluoride (PVDF) thin film sensors: silver ink with a protective coating of urethane, silver ink without a protective coating, and nickel-copper alloy without a protective coating. The methods of sensor integration include placement at the midplane between the layers of prepreg material as well as a sandwich configuration in which a PVDF thin film sensor is placed between the first and second and nineteenth and twentieth layers of prepreg. Each PVDF sensor is continuous and occupies the entire layer, lying in the plane normal to the thickness direction in laminated composites. The work described here is part of an ongoing effort to understand the structural effects of integrating microsensor networks into a host composite material.

Optimation of particle size and composition in fabrication of granite particle composite floortiles

International Nuclear Information System (INIS)

Budiarto; Parikin; Mohammad-Dani

2004-01-01

Granite particle composite floortile materials, that have epoxy matrix, may be utilized as water resist and ductile materials. The utility of composite materials for industrial households is, however, very important and very promising indeed. Starting from powdering the granite refuges into particles of 100, 140 and 200 in mesh, the powder was mixed by epoxy containing versamid hardener and stirred till highly homogenized. Specimens were mould in glass frame and dried in ambient temperature for 48 hours. The specimens were prepared into certain dimensions, conformed to testing needs: hardness, density, compression and bending. The hardness and density data show clearly the value change of particulate composition (34, 40, 50 and 70) and matrix (66, 60, 50 and 30) as well. From bending and compression tests, the optimum grain size (μm) and composition (%) of granite particles reveal between the number of 120-123 and 55-61 respectively. The accurate point of the values can be determined by using differential method. As conclusion, for the better mechanical properties of granite particles composite floortiles, the grains should be 121 in μm and 57% composition of granite particles

Evaluación de diferentes granulometrías de calcio en la alimentación de gallinas ponedoras

Directory of Open Access Journals (Sweden)

Rosa Angélica Sanmiguel-Plazas

2016-11-01

Full Text Available En los últimos años, diversos estudios se han realizado para evaluar el efecto de la granulometría del calcio en la alimentación de gallinas ponedoras, dada su importancia en la eficiencia de la absorción de este mineral para la calcificación del huevo, especialmente en épocas en las que el ave disminuye el consumo de alimento; sin embargo, los resultados obtenidos son controvertidos. En el presente trabajo se propuso evaluar el efecto del tamaño de la partícula de calcio sobre el porcentaje de postura, el consumo de alimento, el peso del huevo y la conversión alimenticia. Se sometieron 120 gallinas ponedoras de la línea Hy-line blanca de 90 semanas de edad, distribuidas al azar, y se aplicaron 4 tratamientos, cada uno con partículas de calcio de diferente tamaño: T1=menor a 1 mm, T2=3 mm, T3=6 mm y T4= 9 mm; cada tratamiento tuvo 10 repeticiones de 3 aves en cada unidad experimental. Hubo un efecto cuadrático para el porcentaje de postura entre los tratamientos a medida que aumentó el tamaño de partícula hasta el tratamiento T3, siendo el tratamiento T4 el que presentó menor porcentaje de postura y menor consumo de ración. Aunque no hubo diferencias significativas entre los tratamientos para el peso del huevo, la conversión alimenticia fue mejor en el tratamiento T4. Se concluye que es posible utilizar los tamaños de partícula de 3 mm y 6 mm sin afectar negativamente los parámetros de desempeño animal en gallinas ponedoras de más de 90 semanas de edad.

Pressure and compressibility factor of bidisperse magnetic fluids

Science.gov (United States)

Minina, Elena S.; Blaak, Ronald; Kantorovich, Sofia S.

2018-04-01

In this work, we investigate the pressure and compressibility factors of bidisperse magnetic fluids with relatively weak dipolar interactions and different granulometric compositions. In order to study these properties, we employ the method of diagram expansion, taking into account two possible scenarios: (1) dipolar particles repel each other as hard spheres; (2) the polymer shell on the surface of the particles is modelled through a soft-sphere approximation. The theoretical predictions of the pressure and compressibility factors of bidisperse ferrofluids at different granulometric compositions are supported by data obtained by means of molecular dynamics computer simulations, which we also carried out for these systems. Both theory and simulations reveal that the pressure and compressibility factors decrease with growing dipolar correlations in the system, namely with an increasing fraction of large particles. We also demonstrate that even if dipolar interactions are too weak for any self-assembly to take place, the interparticle correlations lead to a qualitative change in the behaviour of the compressibility factors when compared to that of non-dipolar spheres, making the dependence monotonic.

Optimizing feeding composition and carbon-nitrogen ratios for improved methane yield during anaerobic co-digestion of dairy, chicken manure and wheat straw.

Science.gov (United States)

Wang, Xiaojiao; Yang, Gaihe; Feng, Yongzhong; Ren, Guangxin; Han, Xinhui

2012-09-01

This study investigated the possibilities of improving methane yield from anaerobic digestion of multi-component substrates, using a mixture of dairy manure (DM), chicken manure (CM) and wheat straw (WS), based on optimized feeding composition and the C/N ratio. Co-digestion of DM, CM and WS performed better in methane potential than individual digestion. A larger synergetic effect in co-digestion of DM, CM and WS was found than in mixtures of single manures with WS. As the C/N ratio increased, methane potential initially increased and then declined. C/N ratios of 25:1 and 30:1 had better digestion performance with stable pH and low concentrations of total ammonium nitrogen and free NH(3). Maximum methane potential was achieved with DM/CM of 40.3:59.7 and a C/N ratio of 27.2:1 after optimization using response surface methodology. The results suggested that better performance of anaerobic co-digestion can be fulfilled by optimizing feeding composition and the C/N ratio. Copyright © 2012 Elsevier Ltd. All rights reserved.

Optimization strategies for discrete multi-material stiffness optimization

DEFF Research Database (Denmark)

Hvejsel, Christian Frier; Lund, Erik; Stolpe, Mathias

2011-01-01

Design of composite laminated lay-ups are formulated as discrete multi-material selection problems. The design problem can be modeled as a non-convex mixed-integer optimization problem. Such problems are in general only solvable to global optimality for small to moderate sized problems. To attack...... which numerically confirm the sought properties of the new scheme in terms of convergence to a discrete solution....

Risk modelling in portfolio optimization

Science.gov (United States)

Lam, W. H.; Jaaman, Saiful Hafizah Hj.; Isa, Zaidi

2013-09-01

Risk management is very important in portfolio optimization. The mean-variance model has been used in portfolio optimization to minimize the investment risk. The objective of the mean-variance model is to minimize the portfolio risk and achieve the target rate of return. Variance is used as risk measure in the mean-variance model. The purpose of this study is to compare the portfolio composition as well as performance between the optimal portfolio of mean-variance model and equally weighted portfolio. Equally weighted portfolio means the proportions that are invested in each asset are equal. The results show that the portfolio composition of the mean-variance optimal portfolio and equally weighted portfolio are different. Besides that, the mean-variance optimal portfolio gives better performance because it gives higher performance ratio than the equally weighted portfolio.

Optimization of tribological performance of SiC embedded composite coating via Taguchi analysis approach

Science.gov (United States)

Maleque, M. A.; Bello, K. A.; Adebisi, A. A.; Akma, N.

2017-03-01

Tungsten inert gas (TIG) torch is one of the most recently used heat source for surface modification of engineering parts, giving similar results to the more expensive high power laser technique. In this study, ceramic-based embedded composite coating has been produced by precoated silicon carbide (SiC) powders on the AISI 4340 low alloy steel substrate using TIG welding torch process. A design of experiment based on Taguchi approach has been adopted to optimize the TIG cladding process parameters. The L9 orthogonal array and the signal-to-noise was used to study the effect of TIG welding parameters such as arc current, travelling speed, welding voltage and argon flow rate on tribological response behaviour (wear rate, surface roughness and wear track width). The objective of the study was to identify optimal design parameter that significantly minimizes each of the surface quality characteristics. The analysis of the experimental results revealed that the argon flow rate was found to be the most influential factor contributing to the minimum wear and surface roughness of the modified coating surface. On the other hand, the key factor in reducing wear scar is the welding voltage. Finally, a convenient and economical Taguchi approach used in this study was efficient to find out optimal factor settings for obtaining minimum wear rate, wear scar and surface roughness responses in TIG-coated surfaces.

Genetic algorithm for design and manufacture optimization based on numerical simulations applied to aeronautic composite parts

International Nuclear Information System (INIS)

Mouton, S.; Ledoux, Y.; Teissandier, D.; Sebastian, P.

2010-01-01

A key challenge for the future is to reduce drastically the human impact on the environment. In the aeronautic field, this challenge aims at optimizing the design of the aircraft to decrease the global mass. This reduction leads to the optimization of every part constitutive of the plane. This operation is even more delicate when the used material is composite material. In this case, it is necessary to find a compromise between the strength, the mass and the manufacturing cost of the component. Due to these different kinds of design constraints it is necessary to assist engineer with decision support system to determine feasible solutions. In this paper, an approach is proposed based on the coupling of the different key characteristics of the design process and on the consideration of the failure risk of the component. The originality of this work is that the manufacturing deviations due to the RTM process are integrated in the simulation of the assembly process. Two kinds of deviations are identified: volume impregnation (injection phase of RTM process) and geometrical deviations (curing and cooling phases). The quantification of these deviations and the related failure risk calculation is based on finite element simulations (Pam RTM registered and Samcef registered softwares). The use of genetic algorithm allows to estimate the impact of the design choices and their consequences on the failure risk of the component. The main focus of the paper is the optimization of tool design. In the framework of decision support systems, the failure risk calculation is used for making the comparison of possible industrialization alternatives. It is proposed to apply this method on a particular part of the airplane structure: a spar unit made of carbon fiber/epoxy composite.

A Hybrid Multiobjective Discrete Particle Swarm Optimization Algorithm for a SLA-Aware Service Composition Problem

Directory of Open Access Journals (Sweden)

Hao Yin

2014-01-01

Full Text Available For SLA-aware service composition problem (SSC, an optimization model for this algorithm is built, and a hybrid multiobjective discrete particle swarm optimization algorithm (HMDPSO is also proposed in this paper. According to the characteristic of this problem, a particle updating strategy is designed by introducing crossover operator. In order to restrain particle swarm’s premature convergence and increase its global search capacity, the swarm diversity indicator is introduced and a particle mutation strategy is proposed to increase the swarm diversity. To accelerate the process of obtaining the feasible particle position, a local search strategy based on constraint domination is proposed and incorporated into the proposed algorithm. At last, some parameters in the algorithm HMDPSO are analyzed and set with relative proper values, and then the algorithm HMDPSO and the algorithm HMDPSO+ incorporated by local search strategy are compared with the recently proposed related algorithms on different scale cases. The results show that algorithm HMDPSO+ can solve the SSC problem more effectively.

Synthesis and optimization of Ag–TiO2 composite nanofibers for photocatalytic treatment of impaired water sources

International Nuclear Information System (INIS)

Nalbandian, Michael J.; Zhang, Miluo; Sanchez, Joel; Kim, Seil; Choa, Yong-Ho; Cwiertny, David M.; Myung, Nosang V.

2015-01-01

Highlights: • We synthesized tunable Ag–TiO 2 nanofibers via electrospinning. • We examined property changes due to the addition of the co-catalyst Ag. • Photocatalytic activity against phenol was studied under UV irradiation. • The 0.5 at.% Ag–TiO 2 showed optimal photocatalytic activity. • The enhanced performance was associated with electron trap mechanism. - Abstract: In this work, Ag–TiO 2 composite nanofibers were fabricated by electrospinning, where the composition and crystallinity were tuned by controlling the precursor composition and annealing conditions. Characterization revealed that bulk–embedded Ag nanoparticles inhibited anatase-to-rutile phase transformation and a decrease in band gap from 3.2 down to 2.8 eV with increase in the Ag content. The photocatalytic activity of 0.5 at.% Ag–TiO 2 nanofibers toward phenol degradation was the greatest, outperforming both unmodified TiO 2 nanofibers and commercially available TiO 2 Aeroxide ® P25 by a factor of ∼3. The high reactivity of the low content Ag–TiO 2 nanofibers can be attributed to the addition of electron traps, which provide efficient carrier separation and, therefore, decreased recombination. However, further increase in Ag content led to lower photoreactivity, most likely due to the growth of the Ag nanoparticles, which suggests an optimal size of 2 to 3 nm for the Ag nanoparticles at 0.5 at.% provided the greatest photoreactivity. Ag–TiO 2 nanofibers show great promise as innovative and highly performing nanomaterials for future nanotechnology-based treatment systems, particularly when the photoreactivity demonstrate herein is used in synergy with the established antimicrobial activity of nano-Ag.

Analysis and optimization of machining parameters of laser cutting for polypropylene composite

Science.gov (United States)

Deepa, A.; Padmanabhan, K.; Kuppan, P.

2017-11-01

Present works explains about machining of self-reinforced Polypropylene composite fabricated using hot compaction method. The objective of the experiment is to find optimum machining parameters for Polypropylene (PP). Laser power and Machining speed were the parameters considered in response to tensile test and Flexure test. Taguchi method is used for experimentation. Grey Relational Analysis (GRA) is used for multiple process parameter optimization. ANOVA (Analysis of Variance) is used to find impact for process parameter. Polypropylene has got the great application in various fields like, it is used in the form of foam in model aircraft and other radio-controlled vehicles, thin sheets (∼2-20μm) used as a dielectric, PP is also used in piping system, it is also been used in hernia and pelvic organ repair or protect new herrnis in the same location.

Artificial Intelligence Based Optimization for the Se(IV) Removal from Aqueous Solution by Reduced Graphene Oxide-Supported Nanoscale Zero-Valent Iron Composites.

Science.gov (United States)

Cao, Rensheng; Fan, Mingyi; Hu, Jiwei; Ruan, Wenqian; Wu, Xianliang; Wei, Xionghui

2018-03-15

Highly promising artificial intelligence tools, including neural network (ANN), genetic algorithm (GA) and particle swarm optimization (PSO), were applied in the present study to develop an approach for the evaluation of Se(IV) removal from aqueous solutions by reduced graphene oxide-supported nanoscale zero-valent iron (nZVI/rGO) composites. Both GA and PSO were used to optimize the parameters of ANN. The effect of operational parameters (i.e., initial pH, temperature, contact time and initial Se(IV) concentration) on the removal efficiency was examined using response surface methodology (RSM), which was also utilized to obtain a dataset for the ANN training. The ANN-GA model results (with a prediction error of 2.88%) showed a better agreement with the experimental data than the ANN-PSO model results (with a prediction error of 4.63%) and the RSM model results (with a prediction error of 5.56%), thus the ANN-GA model was an ideal choice for modeling and optimizing the Se(IV) removal by the nZVI/rGO composites due to its low prediction error. The analysis of the experimental data illustrates that the removal process of Se(IV) obeyed the Langmuir isotherm and the pseudo-second-order kinetic model. Furthermore, the Se 3d and 3p peaks found in XPS spectra for the nZVI/rGO composites after removing treatment illustrates that the removal of Se(IV) was mainly through the adsorption and reduction mechanisms.

Structural and compositional optimization of the LiNi{sub 0.8}Co{sub 0.2}O{sub 2} electrode by new synthesis conditions

Energy Technology Data Exchange (ETDEWEB)

Mosqueda L, Y.; Milian P, C. R.; Pomares A, M.; Rodriguez H, J.; Perez C, E., E-mail: yodalgis@imre.oc.uh.cu [Havana University, Institute of Materials Science and Technology, Zapata y G, Plaza de la Revolucion, Vedado, 10400 Havana (Cuba)

2012-07-01

The optimization of citrate precursor method to obtain the LiNi{sub 0.8}Co{sub 0.2}O{sub 2} oxide from the thermal decomposition of the citrate precursor (NH{sub 4}){sub 3}LiNi{sub 0.8}Co{sub 0.2}(C{sub 6}H{sub 5}O{sub 7}) is presented. The optimization procedure consists of both the lithium atmosphere and the reaction time control during the decomposition of the citrate precursor. Were obtained and characterized two kind of the (Li{sub l-x}Ni{sub x})(Ni{sub 0.8}Co{sub 0.2})O{sub 2} oxides, with and without optimized synthesis conditions, identified as A and B oxides, respectively. The A and B oxides are characterized by compositional, structural and electrochemical studies. The results showed that is possible to reach the ordered oxide phase at smaller reaction time if the lithium atmosphere is controlled. From the combination of the chemical analysis by Icp and the DRX Rietveld structural refinement it is possible to establish the Li, Ni(II), Ni(III) and Co(III) composition with great accuracy. The resulted structural and compositional transformations have a close relation with technological parameters of the rechargeable lithium battery using Li Ni{sub 0.8}Co{sub 0.2}O{sub 2} oxide as cathode. (Author)

Development of a structural optimization capability for the aeroelastic tailoring of composite rotor blades with straight and swept tips

Science.gov (United States)

Friedmann, P. P.; Venkatesan, C.; Yuan, K.

1992-01-01

This paper describes the development of a new structural optimization capability aimed at the aeroelastic tailoring of composite rotor blades with straight and swept tips. The primary objective is to reduce vibration levels in forward flight without diminishing the aeroelastic stability margins of the blade. In the course of this research activity a number of complicated tasks have been addressed: (1) development of a new, aeroelastic stability and response analysis; (2) formulation of a new comprehensive sensitive analysis, which facilitates the generation of the appropriate approximations for the objective and the constraints; (3) physical understanding of the new model and, in particular, determination of its potential for aeroelastic tailoring, and (4) combination of the newly developed analysis capability, the sensitivity derivatives and the optimizer into a comprehensive optimization capability. The first three tasks have been completed and the fourth task is in progress.

Optimum stacking sequence design of laminated composite circular plates with curvilinear fibres by a layer-wise optimization method

Science.gov (United States)

Guenanou, A.; Houmat, A.

2018-05-01

The optimum stacking sequence design for the maximum fundamental frequency of symmetrically laminated composite circular plates with curvilinear fibres is investigated for the first time using a layer-wise optimization method. The design variables are two fibre orientation angles per layer. The fibre paths are constructed using the method of shifted paths. The first-order shear deformation plate theory and a curved square p-element are used to calculate the objective function. The blending function method is used to model accurately the geometry of the circular plate. The equations of motion are derived using Lagrange's method. The numerical results are validated by means of a convergence test and comparison with published values for symmetrically laminated composite circular plates with rectilinear fibres. The material parameters, boundary conditions, number of layers and thickness are shown to influence the optimum solutions to different extents. The results should serve as a benchmark for optimum stacking sequences of symmetrically laminated composite circular plates with curvilinear fibres.

Study and optimization of the composite nuclear fuel with burnable poison UO2/Gd2O3

International Nuclear Information System (INIS)

Balestrieri, D.

1995-09-01

The studied composite ceramics is a nuclear fuel constituted of a uranium dioxide matrix UO 2 in which big grains (or 'macro-masses') of gadolinium oxide (Gd 2 O 3 ) of 300 ± 100 μm of diameter (mass fraction of 12%) are dispersed. Used as burnable poison (neutron absorbent whose action disappears progressively during the irradiation), gadolinium oxide is the object of a particular attention because some of its properties as the crystal structure, the aptitude to sintering and the thermomechanical behavior have been studied. The aim of this work is to perfect and optimize the process of manufacture of the composite in order to answer to accurate specifications for the density, the shape and the mass fraction of macro-masses. In this framework, it has been necessary to strengthen the Gd 2 O 3 macro-masses by a thermal treatment in order to avoid their deformation during the uniaxial pressing. The influence of this pre-consolidation on the ended microstructure, the aptitude to sintering and the thermal conductivity of the composite have been studied. (O.M.)

Applying a Dynamic Stomatal Optimization to Predict Shifts in the Functional Composition of Tropical Forests Under Increased Drought And CO2

Science.gov (United States)

Bartlett, M. K.; Detto, M.; Pacala, S. W.

2017-12-01

The accurate prediction of tropical forest carbon fluxes is key to forecasting global climate, but forest responses to projected increases in CO2 and drought are highly uncertain. Here we present a dynamic optimization that derives the trajectory of stomatal conductance (gs) during drought, a key source of model uncertainty, from plant and soil water relations and the carbon economy of the plant hydraulic system. This optimization scheme is novel in two ways. First, by accounting for the ability of capacitance (i.e., the release of water from plant storage tissue; C) to buffer evaporative water loss and maintain gs during drought, this optimization captures both drought tolerant and avoidant hydraulic strategies. Second, by determining the optimal trajectory of plant and soil water potentials, this optimization quantifies species' impacts on the water available to competing plants. These advances allowed us to apply this optimization across the range of physiology trait values observed in tropical species to evaluate shifts in the competitively optimal trait values, or evolutionarily stable hydraulic strategy (ESS), under increased drought and CO2. Increasing the length of the dry season shifted the ESS towards more drought tolerant, rather than avoidant, trait values, and these shifts were larger for longer individual drought periods (i.e., more consecutive days without rainfall), even if the total time spent in drought was the same. Concurrently doubling the CO2 level reduced the magnitude of these shifts and slightly favored drought avoidant strategies under wet conditions. Overall, these analyses predicted that short, frequent droughts would allow elevated CO2 to shift the functional composition in tropical forests towards more drought avoidant species, while infrequent but long drought periods would shift the ESS to more drought tolerant trait values, despite increased CO2. Overall, these analyses quantified the impact of physiology traits on plant performance

Optimization of multiroute synthesis for polyaniline-barium ferrite composites

Energy Technology Data Exchange (ETDEWEB)

Ben Ghzaiel, Tayssir, E-mail: tayssir.ben-ghzaiel@satie.ens-cachan.fr [Université de Tunis El Manar Faculté des Sciences de Tunis, UR11ES18 Unité de Recherche de Chimie Minérale Appliquée, 2092, Tunis (Tunisia); SATIE, ENS Cachan, CNRS, Université Paris-Saclay, 61 av du Président Wilson, F-94230, Cachan (France); Dhaoui, Wadia [Université de Tunis El Manar Faculté des Sciences de Tunis, UR11ES18 Unité de Recherche de Chimie Minérale Appliquée, 2092, Tunis (Tunisia); Pasko, Alexander; Mazaleyrat, Frédéric [SATIE, ENS Cachan, CNRS, Université Paris-Saclay, 61 av du Président Wilson, F-94230, Cachan (France)

2016-08-15

A comparative study of physicochemical and magnetic properties of Polyaniline-BaFe{sub 12}O{sub 19} composites prepared by Solid-Based Polymerization (SBP) and by Aqueous-Based Polymerization (ABP) is carried out. The composites obtained by the latter method underwent a grinding to study the influence of shear stress. Thus, in a systematic approach, an investigation of stirring effect was done by synthesizing these composites using aqueous-based polymerization but without mechanical stirring. Different mass ratio of BaFe{sub 12}O{sub 19} was used to explore their impact on composites properties. X-ray diffraction, FTIR, SEM, TGA, conductivity and vibrating sample magnetometer measurements were performed. Structural and morphological investigations confirmed the presence of polyaniline and barium hexaferrite phase, which were in interaction in the composites regardless the polymerization route. The powder obtained by solid-based pathway revealed distinct particles with uniform distribution for various compositions (wt. %) of BaFe{sub 12}O{sub 19} in Pani, while the composites obtained by aqueous-based polymerization presented agglomerated nanostructures. Thermogravimetric analysis exhibited an improved thermal stability for Pani-BaFe{sub 12}O{sub 19} obtained by solid-based route. The electric conductivity has displayed decreasing trend of DC conductivity with the increase of BaFe{sub 12}O{sub 19} particles in the polymer matrix. Magnetic studies showed a ferromagnetic behaviour for all composites. The saturation magnetization monotonously increased with the increasing of BaFe{sub 12}O{sub 19} amount. The magnetic properties of the powders were mainly related to the hexaferrite loading which was determined using measured magnetic data. These results revealed that magnetization saturation was dependant of volume fraction of ferrite in the composites which was significantly affected by the reaction medium and mechanical stirring. The powders obtained by solid

Investigation on the utilization of ZrO2-SiO2 composite microspheres for Sr+2 sorption synthesized via sol-gel method

International Nuclear Information System (INIS)

Inan, S.; Tel, H.; Altas, Y.; Eral, M.; Sert, S.; Cetinkaya, B.; Kaplan, U.

2009-01-01

Sr-90 is a typical fission product with a half life of approximately 30 years. The removal of long lived radiotoxic strontium from liquid radioactive waste is an important issue for the health safety. Besides, it reduces the storage problems and facilitates the disposal of the waste. Several methods are utilized for the removal of strontium from liquid radioactive waste. One of the important methods is adsorption processes using metal oxides. Especially, sorbents such as hydrous oxides of titanium, silicium and zirconium and their mixtures, titanium and zirconium phosphates, crystalline silico-titanate(CST) have a good thermal and radiation stability, chemical stability even in strong acidic media, high sorption capacity and compatibility to immobilisation step. The major disadvantage of synthetic inorganic sorbents is their unsuitable granulometric and mechanical properties to use in column applications. Preparation of homogen and uniform spherical particles of these composite sorbents by sol-gel method improves the flow dynamics for column operation and extends its practical applications in industry. In this study, ZrO 2 -SiO 2 composite microspheres were synthesized by sol-gel method. for the sorption of Sr 2 +. The optimum Sr 2 + adsorption conditions were determined by 'Central Composite Design' (CCD). Thermodynamic parameters related to adsorption such as ΔHo, ΔSo and ΔGo were calculated. The adsorption data have been interpreted in terms of Langmuir, Freundlich and D-R isotherms.

Optimization of Laminated Composite Plates

Science.gov (United States)

1989-09-01

plane loads has already been studied, and a number of technical publications and software packages can be found. In the present report, an optimization of...described above. There is no difficulty in any case, and comercial software , from personal computers to macro- systems, is available. In the chapter...Reforzado y su Aplicacion a los Medios de Transporte", Ph.D. University of Zaragoza, Spain, 1984. 77. Miravete A., "Caracterisation et mise au Point d’un

Optimization of Palmitic Acid Composition in Crude Oleic Acid to Provide Specifications of Titer and Cloud Point of Distillate Oleic Acid using a Flash Distiller

OpenAIRE

Muhammad Yusuf Ritonga

2010-01-01

Titer and cloud point Distilled Oleic Acid’s higher than standard on feed composition palmitic acid (C15H31COOH) or C16 11.2 %. Feed composition C16, top temperature precut and bottom main distiller column were optimized to produce DOA. A factorial design 3 independent variables 3 X 2 X 3, twice repeating’s applied to observe effects of feed composition C16 to quality parameters. On the optimum C16 feed composition at 5.20 % was produced DOA with titer 6.8 oC, cloud point 5.0 oC (inside it...

Formation of optimal construction fleet composition

Science.gov (United States)

Tuskaeva, Zalina

2017-10-01

Machinery supply and its rational use in construction processes considerably determine the final product of construction organizations. Therefore, the problem of defining the type size composition of the construction fleet as one of the lowest material-intensive productions, is of a particular importance.

Design and Optimization of a Composite Canard Control Surface of an Advanced Fighter Aircraft under Static Loading

Directory of Open Access Journals (Sweden)

Shrivastava Sachin

2015-01-01

Full Text Available The minimization of weight and maximization of payload is an ever challenging design procedure for air vehicles. The present study has been carried out with an objective to redesign control surface of an advanced all-metallic fighter aircraft. In this study, the structure made up of high strength aluminum, titanium and ferrous alloys has been attempted to replace by carbon fiber composite (CFC skin, ribs and stiffeners. This study presents an approach towards development of a methodology for optimization of first-ply failure index (FI in unidirectional fibrous laminates using Genetic-Algorithms (GA under quasi-static loading. The GAs, by the application of its operators like reproduction, cross-over, mutation and elitist strategy, optimize the ply-orientations in laminates so as to have minimum FI of Tsai-Wu first-ply failure criterion. The GA optimization procedure has been implemented in MATLAB and interfaced with commercial software ABAQUS using python scripting. FI calculations have been carried out in ABAQUS with user material subroutine (UMAT. The GA's application gave reasonably well-optimized ply-orientations combination at a faster convergence rate. However, the final optimized sequence of ply-orientations is obtained by tweaking the sequences given by GA's based on industrial practices and experience, whenever needed. The present study of conversion of an all metallic structure to partial CFC structure has led to 12% of weight reduction. Therefore, the approach proposed here motivates designer to use CFC with a confidence.

Volumetric composition in composites and historical data

DEFF Research Database (Denmark)

Lilholt, Hans; Madsen, Bo

2013-01-01

The obtainable volumetric composition in composites is of importance for the prediction of mechanical and physical properties, and in particular to assess the best possible (normally the highest) values for these properties. The volumetric model for the composition of (fibrous) composites gives...... guidance to the optimal combination of fibre content, matrix content and porosity content, in order to achieve the best obtainable properties. Several composite materials systems have been shown to be handleable with this model. An extensive series of experimental data for the system of cellulose fibres...... and polymer (resin) was produced in 1942 – 1944, and these data have been (re-)analysed by the volumetric composition model, and the property values for density, stiffness and strength have been evaluated. Good agreement has been obtained and some further observations have been extracted from the analysis....

Statistical Optimization of Medium Compositions for High Cell Mass and Exopolysaccharide Production by Lactobacillus plantarum ATCC 8014

Directory of Open Access Journals (Sweden)

Nor Zalina Othman

2018-03-01

Full Text Available Background and Objective: Lactobacillus plantarum ATCC 8014 is known as a good producer of water soluble exopolysaccharide. Therefore, the aim of this study is to optimize the medium composition concurrently for high cell mass and exopolysaccharide production by Lactobacillus plantarum ATCC 8014. Since both are useful for food and pharmaceutical application and where most studies typically focus on one outcome only, the optimization process was carried out by using molasses as cheaper carbon source.Material and Methods: The main medium component which is known significantly give high effect on the cell mass and EPS production was selected as variables and statistically optimized based on Box-Behnken design in shake flask levels. The optimal medium for cell mass and exopolysaccharide production was composed of (in g l -1: molasses, 40; yeast extract, 16.8; phosphate, 2.72; sodium acetate, 3.98. The model was found to be significant and subsequently validated through the growth kinetics studies in un-optimized and optimized medium in the shake flask cultivation.Results and Conclusion: The maximum cell mass and exopolysaccharide in the new optimized medium was 4.40 g l-1 and 4.37 g l-1 respectively after 44 h of the cultivation. As a result, cell mass and exopolysaccharide production increased up to 4.5 and 16.5 times respectively, and the maximal exopolysaccharide yield of 1.19 per gram of cells was obtained when molasses was used as the carbon source. In conclusion, molasses has the potential to be a cheap carbon source for the cultivation of Lactobacillus plantarum ATCC 8014 concurrently for high cell mass and exopolysaccharide production.Conflict of interest: The authors declare no conflict of interest.

An optimal approach to active damping of nonlinear vibrations in composite plates using piezoelectric patches

International Nuclear Information System (INIS)

Saviz, M R

2015-01-01

In this paper a nonlinear approach to studying the vibration characteristic of laminated composite plate with surface-bonded piezoelectric layer/patch is formulated, based on the Green Lagrange type of strain–displacements relations, by incorporating higher-order terms arising from nonlinear relations of kinematics into mathematical formulations. The equations of motion are obtained through the energy method, based on Lagrange equations and by using higher-order shear deformation theories with von Karman–type nonlinearities, so that transverse shear strains vanish at the top and bottom surfaces of the plate. An isoparametric finite element model is provided to model the nonlinear dynamics of the smart plate with piezoelectric layer/ patch. Different boundary conditions are investigated. Optimal locations of piezoelectric patches are found using a genetic algorithm to maximize spatial controllability/observability and considering the effect of residual modes to reduce spillover effect. Active attenuation of vibration of laminated composite plate is achieved through an optimal control law with inequality constraint, which is related to the maximum and minimum values of allowable voltage in the piezoelectric elements. To keep the voltages of actuator pairs in an allowable limit, the Pontryagin’s minimum principle is implemented in a system with multi-inequality constraint of control inputs. The results are compared with similar ones, proving the accuracy of the model especially for the structures undergoing large deformations. The convergence is studied and nonlinear frequencies are obtained for different thickness ratios. The structural coupling between plate and piezoelectric actuators is analyzed. Some examples with new features are presented, indicating that the piezo-patches significantly improve the damping characteristics of the plate for suppressing the geometrically nonlinear transient vibrations. (paper)

Optimization of tannase production by a novel Klebsiella pneumoniae KP715242 using central composite design

Directory of Open Access Journals (Sweden)

Mukesh Kumar

2015-09-01

Full Text Available A novel tannase producing bacterial strain was isolated from rhizospheric soil of Acacia species and identified as Klebsiella pneumoniae KP715242. A 3.25-fold increase in tannase production was achieved upon optimization with central composite design using response surface methodology. Four variables namely pH, temperature, incubation period, and agitation speed were used to optimize significant correlation between the effects of these variables on tannase production. A second-order polynomial was fitted to data and validated by ANOVA. The results showed a complex relationship between variables and response given that all factors were significant and could explain 99.6% of the total variation. The maximum production was obtained at 5.2 pH, 34.97 °C temperature, 103.34 rpm agitation speed and 91.34 h of incubation time. The experimental values were in good agreement with the predicted ones and the models were highly significant with a correlation coefficient (R2 of 0.99 and a highly significant F-value of 319.37.

Fabrication of compact and stable perovskite films with optimized precursor composition in the fast-growing procedure

Energy Technology Data Exchange (ETDEWEB)

Liu, Tanghao; Zhou, Yuanyuan; Hu, Qin; Chen, Ke; Zhang, Yifei; Yang, Wenqiang; Wu, Jiang; Ye, Fengjun; Luo, Deying; Zhu, Kai; Padture, Nitin P.; Liu, Feng; Russell, Thomas; Zhu, Rui; Gong, Qihuang

2017-06-02

The fast-growing procedure (FGP) provides a simple, high-yield and lead (Pb)-release free method to prepare perovskite films. In the FGP, the ultra-dilute perovskite precursor solution is drop-cast onto a hot (~240 degrees C) substrate, where a perovskite film grows immediately accompanied by the rapid evaporation of the host solvent. In this process, all the raw materials in the precursor solution are deposited into the final perovskite film. The potential pollution caused by Pb can be significantly reduced. Properties of the FGP-processed perovskite films can be modulated by the precursor composition. While CH3NH3Cl (MACl) affects the crystallization process and leads to full surface coverage, CH(NH2)2I (FAI) enhances the thermal stability of the film. Based on the optimized precursor composition of PbI2(1-x)FAI xMACl, x=0.75, FGP-processed planar heterojunction perovskite solar cells exhibit power conversion efficiencies (PCEs) exceeding 15% with suppressed hysteresis and excellent reproducibility.

Teaching learning algorithm based optimization of kerf deviations in pulsed Nd:YAG laser cutting of Kevlar-29 composite laminates

Science.gov (United States)

Gautam, Girish Dutt; Pandey, Arun Kumar

2018-03-01

Kevlar is the most popular aramid fiber and most commonly used in different technologically advanced industries for various applications. But the precise cutting of Kevlar composite laminates is a difficult task. The conventional cutting methods face various defects such as delamination, burr formation, fiber pullout with poor surface quality and their mechanical performance is greatly affected by these defects. The laser beam machining may be an alternative of the conventional cutting processes due to its non-contact nature, requirement of low specific energy with higher production rate. But this process also faces some problems that may be minimized by operating the machine at optimum parameters levels. This research paper examines the effective utilization of the Nd:YAG laser cutting system on difficult-to-cut Kevlar-29 composite laminates. The objective of the proposed work is to find the optimum process parameters settings for getting the minimum kerf deviations at both sides. The experiments have been conducted on Kevlar-29 composite laminates having thickness 1.25 mm by using Box-Benkhen design with two center points. The experimental data have been used for the optimization by using the proposed methodology. For the optimization, Teaching learning Algorithm based approach has been employed to obtain the minimum kerf deviation at bottom and top sides. A self coded Matlab program has been developed by using the proposed methodology and this program has been used for the optimization. Finally, the confirmation tests have been performed to compare the experimental and optimum results obtained by the proposed methodology. The comparison results show that the machining performance in the laser beam cutting process has been remarkably improved through proposed approach. Finally, the influence of different laser cutting parameters such as lamp current, pulse frequency, pulse width, compressed air pressure and cutting speed on top kerf deviation and bottom kerf

Natural fibre selection for composite eco-design

DEFF Research Database (Denmark)

Corona, Andrea; Madsen, Bo; Hauschild, Michael Zwicky

2016-01-01

Natural fibre composites (NFC) are gaining interest in manufacturing because they address some of the environmental problems of traditional composites: use of non-renewable resources, and large impacts related to their production and disposal. Since natural fibres are not yet optimized...... for composite production, it is crucial to identify the most appropriate applications, and determine the optimal fibre/matrix ratio. A methodology is proposed for early-stage decisions support on selection of bio-composite materials. Results help identify the application with the largest reduction...

Free material optimization for laminated plates and shells

DEFF Research Database (Denmark)

Weldeyesus, Alemseged Gebrehiwot; Stolpe, Mathias

2016-01-01

Free Material Optimization (FMO) is a powerful approach for conceptual optimal design of composite structures. The design variable in FMO is the entire elastic material tensor which is allowed to vary almost freely over the design domain. The imposed requirements on the tensor are that it is symm......Free Material Optimization (FMO) is a powerful approach for conceptual optimal design of composite structures. The design variable in FMO is the entire elastic material tensor which is allowed to vary almost freely over the design domain. The imposed requirements on the tensor...

Optimization of direct solvent lipid extraction kinetics on marine trebouxiophycean alga by central composite design – Bioenergy perspective

International Nuclear Information System (INIS)

Mathimani, Thangavel; Uma, Lakshmanan; Prabaharan, Dharmar

2017-01-01

Highlights: • Direct solvent extraction is an appropriate pretreatment for marine C. vulgaris. • 2:1 chloroform/methanol, 1:5 DCW/solvent, 65 °C and 120 min time are optimal variables. • Favorable R"2, Prob > F, F value and desirability ratio for all models was observed. • Precision and compatibility of the optimized process suit well with Picochlorum sp. • Fuel properties of biodiesel comply ASTM, EN and ISO standards. - Abstract: This present work compares various pretreatment techniques, single/binary solvent system, biomass drying methods and biomass particle sizes to ascertain effective lipid extraction process for marine trebouxiophycean microalga Chlorella vulgaris BDUG 91771. Of the tested methods, homogenization or direct solvent extraction (DSE) pretreatment, chloroform/methanol binary solvent system, and ≤600 µm particle size extracted maximum lipid of 22.1% irrespective of different biomass drying methods. Further, considering low energy consumption and industrial feasibility, optimization of DSE process kinetics was performed by central composite design. According to central composite design, high lipid recovery was attained with 2:1 chloroform/methanol ratio, 1:5 dry cell weight/solvent ratio, 65 °C temperature, 120 min reaction time, and it was highly validated by regression analysis, coefficient determination, F-value, coefficient variation, desirability ratio of the models. It is noteworthy that, the optimized DSE process was compatible with another trebouxiophycean alga Picochlorum sp. BDUG 91281 through biological and technical replicates. In a bioenergy outlook, fuel properties of C. vulgaris BDUG 91771 biodiesel such as degree of unsaturation (69.03), long chain saturation factor (2.49), cold filter plugging point (−9.75 °C), cloud point (8.1 °C), pour point (0.66 °C), saponification value (248.2 mg KOH/g), acid value (0.51 mg KOH/g), ash content (0.019%), insoluble impurities (0.022 g/kg) and viscosity (4.1 cSt) comply ASTM

Research on using Mineral Sorbents for A Sorption Process in the Environment Contaminated with Petroleum Substances

Directory of Open Access Journals (Sweden)

Pijarowski Piotr Marek

2014-06-01

Full Text Available A research on diatomite sorbents was carried out to investigate their ability to remove hazardous substances from oil spillages. We used two types of sorbents available on the market with differences in material density and particles size of composition. As sorbents we used Ekoterm oil and unleaded petrol 95 coming from refinery PKN Orlen S.A. Two types of sorbents with similar chemical composition but different granulometric composition were used. They are marked as D1 and C1 samples. The fastest absorbent was C1, but D1 sample was the most absorptive.

Thickness optimization of fiber reinforced laminated composites using the discrete material optimization method

DEFF Research Database (Denmark)

Sørensen, Søren Nørgaard; Lund, Erik

2012-01-01

This work concerns a novel large-scale multi-material topology optimization method for simultaneous determination of the optimum variable integer thickness and fiber orientation throughout laminate structures with fixed outer geometries while adhering to certain manufacturing constraints....... The conceptual combinatorial/integer problem is relaxed to a continuous problem and solved on basis of the so-called Discrete Material Optimization method, explicitly including the manufacturing constraints as linear constraints....

Portfolio optimization with mean-variance model

Science.gov (United States)

Hoe, Lam Weng; Siew, Lam Weng

2016-06-01

Investors wish to achieve the target rate of return at the minimum level of risk in their investment. Portfolio optimization is an investment strategy that can be used to minimize the portfolio risk and can achieve the target rate of return. The mean-variance model has been proposed in portfolio optimization. The mean-variance model is an optimization model that aims to minimize the portfolio risk which is the portfolio variance. The objective of this study is to construct the optimal portfolio using the mean-variance model. The data of this study consists of weekly returns of 20 component stocks of FTSE Bursa Malaysia Kuala Lumpur Composite Index (FBMKLCI). The results of this study show that the portfolio composition of the stocks is different. Moreover, investors can get the return at minimum level of risk with the constructed optimal mean-variance portfolio.

Optimization of Palmitic Acid Composition in Crude Oleic Acid to Provide Specifications of Titer and Cloud Point of Distillate Oleic Acid using a Flash Distiller

Directory of Open Access Journals (Sweden)

Muhammad Yusuf Ritonga

2010-11-01

Full Text Available Titer and cloud point of Distilled Oleic Acid is higher than is the standard on feed composition palmitic acid (C15H31COOH or C16 11.2 %. Feed composition C16, top temperature precut and bottom main distiller column were optimized to produce DOA. A factorial design with 3 independent variables, 3 X 2 X 3, repeated twice as much, is applied to observe effects of feed composition C16 to quality parameters. In the optimum C16, feed composition at 5.20 % produced DOA with titer 6.8 oC, cloud point 5.0 oC (inside its specification.

Foam generation and sample composition optimization for the FOAM-C experiment of the ISS

Science.gov (United States)

Carpy, R.; Picker, G.; Amann, B.; Ranebo, H.; Vincent-Bonnieu, S.; Minster, O.; Winter, J.; Dettmann, J.; Castiglione, L.; Höhler, R.; Langevin, D.

2011-12-01

End of 2009 and early 2010 a sealed cell, for foam generation and observation, has been designed and manufactured at Astrium Friedrichshafen facilities. With the use of this cell, different sample compositions of "wet foams" have been optimized for mixtures of chemicals such as water, dodecanol, pluronic, aethoxisclerol, glycerol, CTAB, SDS, as well as glass beads. This development is performed in the frame of the breadboarding development activities of the Experiment Container FOAM-C for operation in the ISS Fluid Science Laboratory (ISS). The sample cell supports multiple observation methods such as: Diffusing-Wave and Diffuse Transmission Spectrometry, Time Resolved Correlation Spectroscopy [1] and microscope observation, all of these methods are applied in the cell with a relatively small experiment volume 40).

Using Central Composite Experimental Design to Optimize the Degradation of Tylosin from Aqueous Solution by Photo-Fenton Reaction

Directory of Open Access Journals (Sweden)

Abd Elaziz Sarrai

2016-05-01

Full Text Available The feasibility of the application of the Photo-Fenton process in the treatment of aqueous solution contaminated by Tylosin antibiotic was evaluated. The Response Surface Methodology (RSM based on Central Composite Design (CCD was used to evaluate and optimize the effect of hydrogen peroxide, ferrous ion concentration and initial pH as independent variables on the total organic carbon (TOC removal as the response function. The interaction effects and optimal parameters were obtained by using MODDE software. The significance of the independent variables and their interactions was tested by means of analysis of variance (ANOVA with a 95% confidence level. Results show that the concentration of the ferrous ion and pH were the main parameters affecting TOC removal, while peroxide concentration had a slight effect on the reaction. The optimum operating conditions to achieve maximum TOC removal were determined. The model prediction for maximum TOC removal was compared to the experimental result at optimal operating conditions. A good agreement between the model prediction and experimental results confirms the soundness of the developed model.

Nutritional interventions for optimizing healthy body composition in older adults in the community: an umbrella review of systematic reviews.

Science.gov (United States)

Schultz, Timothy J; Roupas, Peter; Wiechula, Richard; Krause, Debra; Gravier, Susan; Tuckett, Anthony; Hines, Sonia; Kitson, Alison

2016-08-01

Optimizing body composition for healthy aging in the community is a significant challenge. There are a number of potential interventions available for older people to support both weight gain (for those who are underweight) and weight loss (for overweight or obese people). While the benefits of weight gain for underweight people are generally clearly defined, the value of weight loss in overweight or obese people is less clear, particularly for older people. This umbrella review aimed to measure the effectiveness of nutritional interventions for optimizing healthy body composition in older adults living in the community and to explore theirqualitative perceptions. The participants were older adults, 60 years of age or older, living in the community. The review examinedsix types of nutritional interventions: (i) dietary programs, (ii) nutritional supplements, (iii) meal replacements, (iv) food groups, (v) food delivery support and eating behavior, and (vi) nutritional counselling or education. This umbrella review considered any quantitative systematic reviews and meta-analyses of effectiveness, or qualitative systematic reviews, or a combination (i.e. comprehensive reviews). The quantitative outcome measures of body composition were: (i) nutritional status (e.g. proportion of overweight or underweight patients); (ii) fat mass (kg), (iii) lean mass or muscle mass (kg), (iv) weight (kg) or BMI (kg/m), (v) bone mass (kg) or bone measures such as bone mineral density, and (vi) hydration status. The phenomena of interestwere the qualitative perceptions and experiences of participants. We developed an iterative search strategy for nine bibliometric databases and gray literature. Critical appraisal of 13 studies was conducted independently in pairs using standard Joanna Briggs Institute tools. Six medium quality and seven high quality studies were identified. Data was extracted independently in pairs from all 13 included studies using the standard Joanna Briggs Institute

Volatile compounds and phenolic composition of virgin olive oil: optimization of temperature and time of exposure of olive pastes to air contact during the mechanical extraction process.

Science.gov (United States)

Servili, Maurizio; Selvaggini, Roberto; Taticchi, Agnese; Esposto, Sonia; Montedoro, GianFrancesco

2003-12-31

The operative conditions of malaxation such as temperature and time of exposure of olive pastes to air contact (TEOPAC) affect volatile and phenolic composition of virgin olive oil (VOO) and, as a consequence, its sensory and healthy qualities. In this paper, optimal temperature and TEOPAC during malaxation were studied, in lab scale, in two Italian cultivars using phenolic compounds, volatile composition, and sensory analysis of VOO as markers. The optimal temperature and TEOPAC, selected by response surface modeling,were cultivar-dependent being 30 min of TEOPAC at the lowest temperature investigated (22 degrees C) and 0 min of TEOPAC at 26 degrees C for Frantoio and Moraiolo cultivars, respectively.

Structural optimization procedure of a composite wind turbine blade for reducing both material cost and blade weight

Science.gov (United States)

Hu, Weifei; Park, Dohyun; Choi, DongHoon

2013-12-01

A composite blade structure for a 2 MW horizontal axis wind turbine is optimally designed. Design requirements are simultaneously minimizing material cost and blade weight while satisfying the constraints on stress ratio, tip deflection, fatigue life and laminate layup requirements. The stress ratio and tip deflection under extreme gust loads and the fatigue life under a stochastic normal wind load are evaluated. A blade element wind load model is proposed to explain the wind pressure difference due to blade height change during rotor rotation. For fatigue life evaluation, the stress result of an implicit nonlinear dynamic analysis under a time-varying fluctuating wind is converted to the histograms of mean and amplitude of maximum stress ratio using the rainflow counting algorithm Miner's rule is employed to predict the fatigue life. After integrating and automating the whole analysis procedure an evolutionary algorithm is used to solve the discrete optimization problem.

Genetic Homogenization of Composite Materials

Directory of Open Access Journals (Sweden)

P. Tobola

2009-04-01

Full Text Available The paper is focused on numerical studies of electromagnetic properties of composite materials used for the construction of small airplanes. Discussions concentrate on the genetic homogenization of composite layers and composite layers with a slot. The homogenization is aimed to reduce CPU-time demands of EMC computational models of electrically large airplanes. First, a methodology of creating a 3-dimensional numerical model of a composite material in CST Microwave Studio is proposed focusing on a sufficient accuracy of the model. Second, a proper implementation of a genetic optimization in Matlab is discussed. Third, an association of the optimization script and a simplified 2-dimensional model of the homogeneous equivalent model in Comsol Multiphysics is proposed considering EMC issues. Results of computations are experimentally verified.

Optimization of culture conditions and medium composition for the production of micrococcin GO5 by Micrococcus sp. GO5.

Science.gov (United States)

Kim, Mi-Hee; Kong, Yoon-Jung; Baek, Hong; Hyun, Hyung-Hwan

2006-01-02

To enhance the production of micrococcin GO5, a bacteriocin produced by Micrococcus sp. GO5, cultivation conditions and medium composition were optimized. The optimal initial pH and temperature for bacteriocin production were 7.0-9.0 and 37 degrees C, respectively. Micrococcus sp. GO5 displayed the highest micrococcin GO5 activity when grown in modified MRS medium that contained lactose or sucrose, rather than glucose, as a carbon source. The maximum bacteriocin activity was obtained in modified MRS medium containing 0.5% tryptone and 1.0% yeast extract as nitrogen sources instead of the other nitrogen sources present in MRS medium. Bacteriocin production was greatly affected by the concentration of K(2)HPO(4); strain GO5 produced eight-fold more bacteriocin in medium containing 2.0-2.5% K(2)HPO(4) than in medium containing 0.2% K(2)HPO(4). The optimal concentration of MgSO(4).7H(2)O for bacteriocin production was 0.5%. The production of micrococcin GO5 was increased 32-fold in shake flask culture and 16-fold in a bioreactor using the optimized medium (TY medium), compared with culturing in MRS medium.

Caracterização química e granulométrica de solos do Golfão maranhense Chemical and granulometric caracterization of soils in the Golfão Maranhense

Directory of Open Access Journals (Sweden)

Gustavo Souza Valladares

2009-01-01

Full Text Available A área de estudo corresponde aos campos flúvio-marinhos com risco de inundação e presença de solos hidromórficos da região do Golfão Maranhense. Os solos dessa região apresentam algum impedimento a drenagem, proximidade com o mar (fonte de sais, condições favoráveis a inundação e aos processos de evaporação. Este conjunto de fatores pode elevar as concentrações de sais solúveis e inviabilizar ou reduzir a produtividade. Foram coletadas 38 amostras de solo em 22 pontos com trado holandês a profundidades variáveis, normalmente de 0 a 20 e de 30 a 50 cm. As amostras foram secas ao ar e analisados atributos químicos e granulométricos. Os solos do golfão maranhense apresentam grande variabilidade e predominam os com argila de atividade alta, alta soma de bases e altos teores de hidrogênio e alumínio. Os teores de magnésio são predominantes em relação aos de cálcio. Apesar da maioria dos solos apresentarem textura argilosa a granulometria é bastante variável. Mesmo com altos teores de magnésio e de sódio o grau de floculação das amostras pode ser considerado alto. Os solos do Golfão Maranhense não se encontram salinizados, porém é necessário manejá-los de maneira adequada para não promover sua salinização.The study area of this study corresponds to fluviomarine fields with flood risk and the presence of hydromorphic soils in the Golfão Maranhense region. The soils of the area present slow drenage, proximity with the sea (salt source and favorable conditions for flood, and evaporation processes. All these factors may increase the concentration of soluble salts and reduce productivity or make it inviable. We collected 38 soil samples in 22 points at variable depths, normally between 0 to 20 and 30 to 50 cm. The samples were air dried and their chemical and granulometric attributes analyzed. The soil of Golfão Maranhense presents high variability of chemical and granulometric attributes, and is predominant

UAV-Based Optical Granulometry as Tool for Detecting Changes in Structure of Flood Depositions

Directory of Open Access Journals (Sweden)

Jakub Langhammer

2017-03-01

Full Text Available This paper presents a new non-invasive technique of granulometric analysis based on the fusion of two imaging techniques, Unmanned Aerial Vehicles (UAV-based photogrammetry and optical digital granulometry. This newly proposed technique produces seamless coverage of a study site in order to analyze the granulometric properties of alluvium and observe its spatiotemporal changes. This proposed technique is tested by observing changes along the point bar of a mid-latitude mountain stream. UAV photogrammetry acquired at a low-level flight altitude (at a height of 8 m is used to acquire ultra-high resolution orthoimages to build high-precision digital terrain models (DTMs. These orthoimages are covered by a regular virtual grid, and the granulometric properties of the grid fields are analyzed using the digital optical granulometric tool BaseGrain. This tested framework demonstrates the applicability of the proposed method for granulometric analysis, which yields accuracy comparable to that of traditional field optical granulometry. The seamless nature of this method further enables researchers to study the spatial distribution of granulometric properties across multiple study sites, as well as to analyze multitemporal changes using repeated imaging.

External force back-projective composition and globally deformable optimization for 3-D coronary artery reconstruction

International Nuclear Information System (INIS)

Yang, Jian; Cong, Weijian; Fan, Jingfan; Liu, Yue; Wang, Yongtian; Chen, Yang

2014-01-01

The clinical value of the 3D reconstruction of a coronary artery is important for the diagnosis and intervention of cardiovascular diseases. This work proposes a method based on a deformable model for reconstructing coronary arteries from two monoplane angiographic images acquired from different angles. First, an external force back-projective composition model is developed to determine the external force, for which the force distributions in different views are back-projected to the 3D space and composited in the same coordinate system based on the perspective projection principle of x-ray imaging. The elasticity and bending forces are composited as an internal force to maintain the smoothness of the deformable curve. Second, the deformable curve evolves rapidly toward the true vascular centerlines in 3D space and angiographic images under the combination of internal and external forces. Third, densely matched correspondence among vessel centerlines is constructed using a curve alignment method. The bundle adjustment method is then utilized for the global optimization of the projection parameters and the 3D structures. The proposed method is validated on phantom data and routine angiographic images with consideration for space and re-projection image errors. Experimental results demonstrate the effectiveness and robustness of the proposed method for the reconstruction of coronary arteries from two monoplane angiographic images. The proposed method can achieve a mean space error of 0.564 mm and a mean re-projection error of 0.349 mm. (paper)

Multidisciplinary Shape Optimization of a Composite Blended Wing Body Aircraft

Science.gov (United States)

Boozer, Charles Maxwell

A multidisciplinary shape optimization tool coupling aerodynamics, structure, and performance was developed for battery powered aircraft. Utilizing high-fidelity computational fluid dynamics analysis tools and a structural wing weight tool, coupled based on the multidisciplinary feasible optimization architecture; aircraft geometry is modified in the optimization of the aircraft's range or endurance. The developed tool is applied to three geometries: a hybrid blended wing body, delta wing UAS, the ONERA M6 wing, and a modified ONERA M6 wing. First, the optimization problem is presented with the objective function, constraints, and design vector. Next, the tool's architecture and the analysis tools that are utilized are described. Finally, various optimizations are described and their results analyzed for all test subjects. Results show that less computationally expensive inviscid optimizations yield positive performance improvements using planform, airfoil, and three-dimensional degrees of freedom. From the results obtained through a series of optimizations, it is concluded that the newly developed tool is both effective at improving performance and serves as a platform ready to receive additional performance modules, further improving its computational design support potential.

The optimal design of UAV wing structure

Science.gov (United States)

Długosz, Adam; Klimek, Wiktor

2018-01-01

The paper presents an optimal design of UAV wing, made of composite materials. The aim of the optimization is to improve strength and stiffness together with reduction of the weight of the structure. Three different types of functionals, which depend on stress, stiffness and the total mass are defined. The paper presents an application of the in-house implementation of the evolutionary multi-objective algorithm in optimization of the UAV wing structure. Values of the functionals are calculated on the basis of results obtained from numerical simulations. Numerical FEM model, consisting of different composite materials is created. Adequacy of the numerical model is verified by results obtained from the experiment, performed on a tensile testing machine. Examples of multi-objective optimization by means of Pareto-optimal set of solutions are presented.

Synthesis and optimization of Ag–TiO{sub 2} composite nanofibers for photocatalytic treatment of impaired water sources

Energy Technology Data Exchange (ETDEWEB)

Nalbandian, Michael J.; Zhang, Miluo; Sanchez, Joel [Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521 (United States); Kim, Seil; Choa, Yong-Ho [Department of Fusion Chemical Engineering, Hanyang University, Ansan, Kyeonggi-do 426-791 (Korea, Republic of); Cwiertny, David M., E-mail: david-cwiertny@uiowa.edu [Department of Civil and Environmental Engineering, University of Iowa, Iowa, IA 52242 (United States); Myung, Nosang V., E-mail: myung@engr.ucr.edu [Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521 (United States)

2015-12-15

Highlights: • We synthesized tunable Ag–TiO{sub 2} nanofibers via electrospinning. • We examined property changes due to the addition of the co-catalyst Ag. • Photocatalytic activity against phenol was studied under UV irradiation. • The 0.5 at.% Ag–TiO{sub 2} showed optimal photocatalytic activity. • The enhanced performance was associated with electron trap mechanism. - Abstract: In this work, Ag–TiO{sub 2} composite nanofibers were fabricated by electrospinning, where the composition and crystallinity were tuned by controlling the precursor composition and annealing conditions. Characterization revealed that bulk–embedded Ag nanoparticles inhibited anatase-to-rutile phase transformation and a decrease in band gap from 3.2 down to 2.8 eV with increase in the Ag content. The photocatalytic activity of 0.5 at.% Ag–TiO{sub 2} nanofibers toward phenol degradation was the greatest, outperforming both unmodified TiO{sub 2} nanofibers and commercially available TiO{sub 2} Aeroxide{sup ®} P25 by a factor of ∼3. The high reactivity of the low content Ag–TiO{sub 2} nanofibers can be attributed to the addition of electron traps, which provide efficient carrier separation and, therefore, decreased recombination. However, further increase in Ag content led to lower photoreactivity, most likely due to the growth of the Ag nanoparticles, which suggests an optimal size of 2 to 3 nm for the Ag nanoparticles at 0.5 at.% provided the greatest photoreactivity. Ag–TiO{sub 2} nanofibers show great promise as innovative and highly performing nanomaterials for future nanotechnology-based treatment systems, particularly when the photoreactivity demonstrate herein is used in synergy with the established antimicrobial activity of nano-Ag.

Optimizing Plutonium stock management

International Nuclear Information System (INIS)

Niquil, Y.; Guillot, J.

1997-01-01

Plutonium from spent fuel reprocessing is reused in new MOX assemblies. Since plutonium isotopic composition deteriorates with time, it is necessary to optimize plutonium stock management over a long period, to guarantee safe procurement, and contribute to a nuclear fuel cycle policy at the lowest cost. This optimization is provided by the prototype software POMAR

Technical Report on the Development of Mutant Paracoccus strain and Optimization of Medium Composition for the Mass Production of Astaxanthin

Energy Technology Data Exchange (ETDEWEB)

Choi, Jong Il; Lee, Ju Woon; Kim, Jae Hun; Song, Beom Seok

2010-08-15

Astaxanthin is used to role of provitamin A, and it is stronger antioxidant activity than vitamin E (100-500 times higher activity) and other carotenoids (10-fold). Furthermore, astaxanthin is also used as a nutraceutical and a medicinal ingredient against degenerative diseases such as cancer, heart disease, and skin related illness. The objective of this study was develop a carotenoid-hyperproducing mutant of Paracoccus N81106 using gamma irradiation and optimized medium composition. A mutant of Paracoccus having higher carotenoid content was isolated, and the production medium was optimized using response surface methodology. These results support that astaxanthin with strong antioxidant activity could be economically produced using the mutant and will be helpful for the related industry

Technical Report on the Development of Mutant Paracoccus strain and Optimization of Medium Composition for the Mass Production of Astaxanthin

International Nuclear Information System (INIS)

Choi, Jong Il; Lee, Ju Woon; Kim, Jae Hun; Song, Beom Seok

2010-08-01

Astaxanthin is used to role of provitamin A, and it is stronger antioxidant activity than vitamin E (100-500 times higher activity) and other carotenoids (10-fold). Furthermore, astaxanthin is also used as a nutraceutical and a medicinal ingredient against degenerative diseases such as cancer, heart disease, and skin related illness. The objective of this study was develop a carotenoid-hyperproducing mutant of Paracoccus N81106 using gamma irradiation and optimized medium composition. A mutant of Paracoccus having higher carotenoid content was isolated, and the production medium was optimized using response surface methodology. These results support that astaxanthin with strong antioxidant activity could be economically produced using the mutant and will be helpful for the related industry

How to apply the optimal estimation method to your lidar measurements for improved retrievals of temperature and composition

Science.gov (United States)

Sica, R. J.; Haefele, A.; Jalali, A.; Gamage, S.; Farhani, G.

2018-04-01

The optimal estimation method (OEM) has a long history of use in passive remote sensing, but has only recently been applied to active instruments like lidar. The OEM's advantage over traditional techniques includes obtaining a full systematic and random uncertainty budget plus the ability to work with the raw measurements without first applying instrument corrections. In our meeting presentation we will show you how to use the OEM for temperature and composition retrievals for Rayleigh-scatter, Ramanscatter and DIAL lidars.

Optimization of medium composition for apple rootstocks

African Journals Online (AJOL)

User

2011-05-02

May 2, 2011 ... Key words: Apple rootstocks, medium composition, multiplication rate, plant growth regulators (PGRs). ... be extrapolated with the same success for another .... Analysis System (SAS) software program (SAS Institute Inc. 1999).

Optimizing the parameters of heat transmission in a small heat exchanger with spiral tapes cut as triangles and Aluminum oxide nanofluid using central composite design method

Science.gov (United States)

Ghasemi, Nahid; Aghayari, Reza; Maddah, Heydar

2018-02-01

The present study aims at optimizing the heat transmission parameters such as Nusselt number and friction factor in a small double pipe heat exchanger equipped with rotating spiral tapes cut as triangles and filled with aluminum oxide nanofluid. The effects of Reynolds number, twist ratio (y/w), rotating twisted tape and concentration (w%) on the Nusselt number and friction factor are also investigated. The central composite design and the response surface methodology are used for evaluating the responses necessary for optimization. According to the optimal curves, the most optimized value obtained for Nusselt number and friction factor was 146.6675 and 0.06020, respectively. Finally, an appropriate correlation is also provided to achieve the optimal model of the minimum cost. Optimization results showed that the cost has decreased in the best case.

Wind sorting affects differently the organo-mineral composition of saltating and particulate materials in contrasting texture agricultural soils

Science.gov (United States)

Iturri, Laura Antonela; Funk, Roger; Leue, Martin; Sommer, Michael; Buschiazzo, Daniel Eduardo

2017-10-01

There is little information about the mineral and organic composition of sediments eroded by wind at different heights. Because of that, wind tunnel simulations were performed on four agricultural loess soils of different granulometry and their saltating materials collected at different heights. The particulate matter with an aerodynamic diameter mainly smaller than 10 μm (PM10) of these soils was obtained separately by a laboratory method. Results indicated that the granulometric composition of sediments collected at different heights was more homogeneous in fine- than in sandy-textured soils, which were more affected by sorting effects during wind erosion. This agrees with the preferential transport of quartz at low heights and of clay minerals at greater heights. SOC contents increased with height, but the composition of the organic materials was different: stable carboxylic acids, aldehydes, amides and aromatics were preferentially transported close to the ground because their were found in larger aggregates, while plant debris and polysaccharides, carbohydrates and derivatives of microbial origin from organic matter dominated at greater heights for all soil types. The amount of SOC in the PM10 fraction was higher when it was emitted from sandy than from fine textured soils. Because of the sorting process produced by wind erosion, the stable organic matter compounds will be transported at low heights and local scales, modifying soil fertility due to nutrient exportation, while less stable organic compounds will be part of the suspension losses, which are known to affect some processes at regional- or global scale.

Optimization of chemical composition in the manufacturing process of flotation balls based on intelligent soft sensing

Directory of Open Access Journals (Sweden)

Dučić Nedeljko

2016-01-01

Full Text Available This paper presents an application of computational intelligence in modeling and optimization of parameters of two related production processes - ore flotation and production of balls for ore flotation. It is proposed that desired chemical composition of flotation balls (Mn=0.69%; Cr=2.247%; C=3.79%; Si=0.5%, which ensures minimum wear rate (0.47 g/kg during copper milling is determined by combining artificial neural network (ANN and genetic algorithm (GA. Based on the results provided by neuro-genetic combination, a second neural network was derived as an ‘intelligent soft sensor’ in the process of white cast iron production. The proposed ANN 12-16-12-4 model demonstrated favourable prediction capacity, and can be recommended as a ‘intelligent soft sensor’ in the alloying process intended for obtaining favourable chemical composition of white cast iron for production of flotation balls. In the development of intelligent soft sensor data from the two real production processes was used. [Projekat Ministarstva nauke Republike Srbije, br. TR35037 i br. TR35015

p-Nitrophenol degradation by electro-Fenton process: Pathway, kinetic model and optimization using central composite design.

Science.gov (United States)

Meijide, J; Rosales, E; Pazos, M; Sanromán, M A

2017-10-01

The chemical process scale-up, from lab studies to industrial production, is challenging and requires deep knowledge of the kinetic model and the reactions that take place in the system. This knowledge is also useful in order to be employed for the reactor design and the determination of the optimal operational conditions. In this study, a model substituted phenol such as p-nitrophenol was degraded by electro-Fenton process and the reaction products yielded along the treatment were recorded. The kinetic model was developed using Matlab software and was based on main reactions that occurred until total mineralization which allowed predicting the degradation pathway under this advanced oxidation process. The predicted concentration profiles of p-nitrophenol, their intermediates and by-products in electro-Fenton process were validated with experimental assays and the results were consistent. Finally, based on the developed kinetic model the degradation process was optimized using central composite design taking as key parameters the ferrous ion concentration and current density. Copyright © 2017 Elsevier Ltd. All rights reserved.

Design and Optimization of Filament Wound Composite Pressure Vessels

NARCIS (Netherlands)

Zu, L.

2012-01-01

One of the most important issues for the design of filament-wound pressure vessels reflects on the determination of the most efficient meridian profiles and related fiber architectures, leading to optimal structural performance. To better understand the design and optimization of filament-wound

Optimization of medium composition for thermostable protease ...

African Journals Online (AJOL)

SERVER

2008-04-17

Apr 17, 2008 ... Optimization of the fermentation medium for maximization of thermostable neutral protease production by Bacillus sp. ..... Each contour curve represented an infinite number of combinations of two ..... Production in sea-water of.

Hybrid filler composition optimization for tensile strength of jute fibre

Indian Academy of Sciences (India)

https://www.ias.ac.in/article/fulltext/boms/039/05/1223-1231 ... The developed composite consists of natural jute fibre as reinforcement and unsaturated ... The effect of weight content of bagasse fibre, carbon black and calcium carbonate ... of pultruded jute fibre polymer composite at the optimum composition of hybrid filler.

Matrix model of the grinding process of cement clinker in the ball mill

Science.gov (United States)

Sharapov, Rashid R.

2018-02-01

In the article attention is paid to improving the efficiency of production of fine powders, in particular Portland cement clinker. The questions of Portland cement clinker grinding in closed circuit ball mills. Noted that the main task of modeling the grinding process is predicting the granulometric composition of the finished product taking into account constructive and technological parameters used ball mill and separator. It is shown that the most complete and informative characterization of the grinding process in a ball mill is a grinding matrix taking into account the transformation of grain composition inside the mill drum. Shows how the relative mass fraction of the particles of crushed material, get to corresponding fraction. Noted, that the actual task of reconstruction of the matrix of grinding on the experimental data obtained in the real operating installations. On the basis of experimental data obtained on industrial installations, using matrix method to determine the kinetics of the grinding process in closed circuit ball mills. The calculation method of the conversion of the grain composition of the crushed material along the mill drum developed. Taking into account the proposed approach can be optimized processing methods to improve the manufacturing process of Portland cement clinker.

On the design of 1-3 piezo-composites using topology optimization

DEFF Research Database (Denmark)

Sigmund, Ole; Torquato, S.; Aksay, I.A.

1998-01-01

(h)((*))g(h)((*)), and the electromechanical coupling factor k(h)((*)). The piezocomposite consists of piezoelectric rods embedded in an optimal polymer matrix. We use the topology optimization method to design the optimal (porous) matrix microstructure. When we design for maximum d(h)((*)) and d(h)((*))g(h)((*)) the optimal transversally......We use a topology optimization method to design 1-3 piezocomposites with optimal performance characteristics for hydrophone applications. The performance characteristics we focus on are the hydrostatic charge coefficient d(h)((*)), the hydrophone figure of merit d...

Optimal Electrode Selection for Electrical Resistance Tomography in Carbon Fiber Reinforced Polymer Composites

Science.gov (United States)

Escalona Galvis, Luis Waldo; Diaz-Montiel, Paulina; Venkataraman, Satchi

2017-01-01

Electrical Resistance Tomography (ERT) offers a non-destructive evaluation (NDE) technique that takes advantage of the inherent electrical properties in carbon fiber reinforced polymer (CFRP) composites for internal damage characterization. This paper investigates a method of optimum selection of sensing configurations for delamination detection in thick cross-ply laminates using ERT. Reduction in the number of sensing locations and measurements is necessary to minimize hardware and computational effort. The present work explores the use of an effective independence (EI) measure originally proposed for sensor location optimization in experimental vibration modal analysis. The EI measure is used for selecting the minimum set of resistance measurements among all possible combinations resulting from selecting sensing electrode pairs. Singular Value Decomposition (SVD) is applied to obtain a spectral representation of the resistance measurements in the laminate for subsequent EI based reduction to take place. The electrical potential field in a CFRP laminate is calculated using finite element analysis (FEA) applied on models for two different laminate layouts considering a set of specified delamination sizes and locations with two different sensing arrangements. The effectiveness of the EI measure in eliminating redundant electrode pairs is demonstrated by performing inverse identification of damage using the full set and the reduced set of resistance measurements. This investigation shows that the EI measure is effective for optimally selecting the electrode pairs needed for resistance measurements in ERT based damage detection. PMID:28772485

Column Adsorption Studies for the Removal of Cr(VI Ions by Ethylamine Modified Chitosan Carbonized Rice Husk Composite Beads with Modelling and Optimization

Directory of Open Access Journals (Sweden)

S. Sugashini

2013-01-01

Full Text Available The objective of this present study is the optimization of process parameters in adsorption of Cr(VI ions by ethylamine modified chitosan carbonized rice husk composite beads (EAM-CCRCBs using response surface methodology (RSM and continuous adsorption studies of Cr(VI ions by ethylamine modified chitosan carbonized rice husk composite beads (EAM-CCRCBs. The effect of process variables such as initial metal ion concentration, adsorbent dosage and pH were optimized using RSM in order to ensure high adsorption capacity at low adsorbent dosage and high initial metal ion concentration of Cr(VI in batch process. The optimum condition suggested by the model for the process variable such as adsorbent dosage, pH and initial metal ion concentration was 0.14 g, 300 mg/L and pH2 with maximum removal of 99.8% and adsorption capacity of 52.7 mg/g respectively. Continuous adsorption studies were conducted under optimized initial metal ion concentration and pH for the removal of Cr(VI ions using EAM-CCRCBs. The breakthrough curve analysis was determined using the experimental data obtained from the continuous adsorption. Continuous adsorption modelling such as bed depth service model and Thomson model were established by fitting it with experimental data.

Optimization of photocatalytic treatment of dye solution on supported TiO2 nanoparticles by central composite design: Intermediates identification

International Nuclear Information System (INIS)

Khataee, A.R.; Fathinia, M.; Aber, S.; Zarei, M.

2010-01-01

Optimization of photocatalytic degradation of C.I. Basic Blue 3 (BB3) under UV light irradiation using TiO 2 nanoparticles in a rectangular photoreactor was studied. The investigated TiO 2 was Millennium PC-500 (crystallites mean size 5-10 nm) immobilized on non-woven paper. Central composite design was used for optimization of UV/TiO 2 process. Predicted values of decolorization efficiency were found to be in good agreement with experimental values (R 2 = 0.9686 and Adj-R 2 = 0.9411). Optimization results showed that maximum decolorization efficiency was achieved at the optimum conditions: initial dye concentration 10 mg/L, UV light intensity 47.2 W/m 2 , flow rate 100 mL/min and reaction time 120 min. Photocatalytic mineralization of BB3 was monitored by total organic carbon (TOC) decrease, and changes in UV-vis and FT-IR spectra. The photodegradation compounds were analyzed by UV-vis, FT-IR and GC-mass techniques. The degradation pathway of BB3 was proposed based on the identified compounds.

Application of central composite design to optimize the amount of carbon source and prebiotics for Bifidobacterium bifidum BB01

Directory of Open Access Journals (Sweden)

Shu Guowei

2016-06-01

Full Text Available The objective of the present study was to obtain the optimum proportion of the carbon source and prebiotics for Bifidobacterium bifidum BB01 by the central composite design (CCD. The effect of carbon source (lactose and two prebiotics (inulin and fructooligosaccharides on the BB01 were observed by measuring the OD600 value, pH value and the viable counts at 18h. The final optimized concentrations of carbon source and prebiotics were: lactose 1.6%, inulin 0.26%, and fructooligosaccharides 0.22%. The result indicates that the growth of B. bifidum BB01 shows an significant increase in the optimized culture medium (p < 0.05, the OD600 value reached 1.434 at 18h, which increased 6.58% compared to the control. And the viable counts of B. bifidum BB01 increased 24.36% and reached (2.17±0.06 ×109cfu/mL. The results show that the optimization of the carbon source and prebiotics using CCD in this study is workable and necessary.

Optimization of Nutrient Composition for Producing ACE Inhibitory Peptides from Goat Milk Fermented by Lactobacillus bulgaricus LB6.

Science.gov (United States)

Shu, Guowei; Shi, Xiaoyu; Chen, He; Ji, Zhe; Meng, Jiangpeng

2018-03-23

Hypertension is a serious threat to human health and food-derived angiotensin converting enzyme (ACE; EC 3.4.15.1) inhibitory peptides can be used to regulate high blood pressure without side effects. The composition of the nutrient medium for the production of these peptides by fermenting goat milk with Lactobacillus bulgaricus LB6 was optimized to increase the ACE inhibitory activity by Box-Behnken design (BBD) of response surface methodology (RSM) in the present study. Soybean peptone, glucose, and casein had significant effects on both ACE inhibition rate and viable counts of L. bulgaricus LB6 during incubation. The results showed that the maximum values of ACE inhibition rate and viable counts for L. bulgaricus LB6 were reaching to 86.37 ± 0.53% and 8.06 × 10 7 under the optimal conditions, which were 0.35% (w/w) soybean peptone, 1.2% (w/w) glucose, and 0.15% (w/w) casein. The results were in close agreement with the model prediction. The optimal values of the medium component concentrations can be a good reference for obtaining ACE inhibitory peptides from goat milk.

Optimization the machining parameters by using VIKOR and Entropy Weight method during EDM process of Al–18% SiCp Metal matrix composit

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Rajesh Kumar Bhuyan

2016-06-01

Full Text Available The objective of this paper is to optimize the process parameters by combined approach of VIKOR and Entropy weight measurement method during Electrical discharge machining (EDM process of Al-18wt.%SiCp metal matrix composite (MMC. The central composite design (CCD method is considered to evaluate the effect of three process parameters; namely pulse on time (Ton, peak current (Ip and flushing pressure (Fp on the responses like material removal rate (MRR, tool wear rate (TWR, Radial over cut (ROC and surface roughness (Ra. The Entropy weight measurement method evaluates the individual weights of each response and, using VIKOR method, the multi-objective responses are optimized to get a single numerical index known as VIKOR Index. Then the Analysis of Variance (ANOVA technique is used to determine the significance of the process parameters on the VIKOR Index. Finally, the result of the VIKOR Indexed is validated by conformation test using the liner mathematical model equation develop by responses surface methodology to identify the effectiveness of the proposed method.

Combined meso-scale modeling and experimental investigation of the effect of mechanical damage on the transport properties of cementitious composites

Science.gov (United States)

Raghavan, Balaji; Niknezhad, Davood; Bernard, Fabrice; Kamali-Bernard, Siham

2016-09-01

The transport properties of cementitious composites such as concrete are important indicators of their durability, and are known to be heavily influenced by mechanical loading. In the current work, we use meso-scale hygro-mechanical modeling with a morphological 3D two phase mortar-aggregate model, in conjunction with experimentally obtained properties, to investigate the coupling between mechanical loading and damage and the permeability of the composite. The increase in permeability of a cylindrical test specimen at 28% aggregate fraction during a uniaxial displacement-controlled compression test at 85% of the peak load was measured using a gas permeameter. The mortar's mechanical behavior is assumed to follow the well-known compression damaged plasticity (CDP) model with isotropic damage, at varying thresholds, and obtained from different envelope curves. The damaged intrinsic permeability of the mortar evolves according to a logarithmic matching law with progressive loading. We fit the matching law parameters to the experimental result for the test specimen by inverse identification using our meso-scale model. We then subject a series of virtual composite specimens to quasi-static uniaxial compressive loading with varying boundary conditions to obtain the simulated damage and strain evolutions, and use the damage data and the previously identified parameters to determine the evolution of the macroscopic permeability tensor for the specimens, using a network model. We conduct a full parameter study by varying aggregate volume fraction, granulometric distribution, loading/boundary conditions and "matching law" parameters, as well as for different strain-damage thresholds and uniaxial loading envelope curves. Based on this study, we propose Avrami equation-based upper and lower bounds for the evolution of the damaged permeability of the composite.

Correction of heterogeneities in the issue compositions in the construction plans optimized in radiotherapy using linear programming

International Nuclear Information System (INIS)

Viana, Rodrigo Sartorelo S.; Lima, Ernesto A.B.F.; Florentino, Helenice de Oliveira; Fonseca, Paulo Roberto da; Homem, Thiago Pedro Donadon

2009-01-01

Linear programming models are widely found in the literature addressing various aspects involved in the creation of optimized planning for radiotherapy. However, most mathematical formulations does not incorporate certain factors that are of extreme importance for the formulation of a real planning like the attenuation of the beam of radiation and heterogeneity in the composition of tissue irradiated. In this context are proposed in this paper some modifications in the formulation of a linear programming problem with the objective of making the simulation closer to the real planning for radiotherapy and thus enable a more reliable and comprehensive planning requirements. (author)

Culture Optimization and Amino Acid Composition of Cr-Enriched Mycelia of Pleurotus cornucopiae SD-01

Directory of Open Access Journals (Sweden)

Fan-Yun Meng

2010-01-01

Full Text Available Chromium(III is an essential trace element for humans and animals. Pleutorus cornucopiae SD-01 is a nutritional and functional mushroom containing many kinds of bioactive ingredients. The aims of this work are to optimize the conditions of P. cornucopiae SD-01 cultivation with Cr enrichment in submerged culture by determining the dry cell mass, Cr content in mycelia and the rate of Cr enrichment, and to analyze the amino acid composition of Cr-enriched mycelia. The optimal medium contained (in g/L: potato 200, sucrose 25, yeast extract 4, KH2PO4 1 and MgSO4·7H2O 1. The optimum parameters of liquid culture were temperature 25 °C, cultivation time 6 days, the volume of the medium 100 mL, rotation speed 160 rpm and initial pH=6.5. Under the optimized conditions, the values of the dry cell mass, Cr content in mycelia and the rate of Cr enrichment were (6.63±0.35 g/L, (3670±211 μg/g and (12.15±1.01 % respectively, which were by (23.23±1.22, (18.19±1.06 and (45.68±2.67 % respectively, higher than those in the control. Chromium(III in Cr-enriched mycelia was mainly combined with protein and polysaccharide. The contents of total amino acids and essential amino acids in Cr-enriched mycelia were increased by (31.25±0.58 and (44.26±0.76 %, respectively.

Optimal determination of the elastic constants of composite materials from ultrasonic wave-speed measurements

Science.gov (United States)

Castagnède, Bernard; Jenkins, James T.; Sachse, Wolfgang; Baste, Stéphane

1990-03-01

A method is described to optimally determine the elastic constants of anisotropic solids from wave-speeds measurements in arbitrary nonprincipal planes. For such a problem, the characteristic equation is a degree-three polynomial which generally does not factorize. By developing and rearranging this polynomial, a nonlinear system of equations is obtained. The elastic constants are then recovered by minimizing a functional derived from this overdetermined system of equations. Calculations of the functional are given for two specific cases, i.e., the orthorhombic and the hexagonal symmetries. Some numerical results showing the efficiency of the algorithm are presented. A numerical method is also described for the recovery of the orientation of the principal acoustical axes. This problem is solved through a double-iterative numerical scheme. Numerical as well as experimental results are presented for a unidirectional composite material.

Optimal assignment of multiple utilities in heat exchange networks

International Nuclear Information System (INIS)

Salama, A.I.A.

2009-01-01

Existing numerical geometry-based techniques, developed by [A.I.A. Salama, Numerical techniques for determining heat energy targets in pinch analysis, Computers and Chemical Engineering 29 (2005) 1861-1866; A.I.A. Salama, Determination of the optimal heat energy targets in heat pinch analysis using a geometry-based approach, Computers and Chemical Engineering 30 (2006) 758-764], have been extended to optimally assign multiple utilities in heat exchange network (HEN). These techniques utilize the horizontal shift between the cold composite curve (CC) and the stationary hot CC to determine the HEN optimal energy targets, grand composite curve (GCC), and the complement grand composite curve (CGCC). The proposed numerical technique developed in this paper is direct and simultaneously determines the optimal heat-energy targets and optimally assigns multiple utilities as compared with an existing technique based on sequential assignment of multiple utilities. The technique starts by arranging in an ascending order the HEN stream and target temperatures, and the resulting set is labelled T. Furthermore, the temperature sets where multiple utilities are introduced are arranged in an ascending order and are labelled T ic and T ih for the cold and hot sides, respectively. The graphical presentation of the results is facilitated by the insertion at each multiple-utility temperature a perturbed temperature equals the insertion temperature minus a small perturbation. Furthermore, using the heat exchanger network (HEN) minimum temperature-differential approach (ΔT min ) and stream heat-capacity flow rates, the presentation is facilitated by using the conventional temperature shift of the HEN CCs. The set of temperature-shifted stream and target temperatures and perturbed temperatures in the overlap range between the CCs is labelled T ol . Using T ol , a simple formula employing enthalpy-flow differences between the hot composite curve CC h and the cold composite curve CC c is

Combined Effect of Synthetic and Natural Polymers in Preparation of Cetirizine Hydrochloride Oral Disintegrating Tablets: Optimization by Central Composite Design.

Science.gov (United States)

Patro, Chandra Sekhar; Sahu, Prafulla Kumar

2017-01-01

Our aim was to employ experimental design to formulate and optimize cetirizine hydrochloride oral disintegrating tablets (ODTs) by direct compression technique, using the mutual effect of synthetic croscarmellose sodium (CCS) and natural Hibiscus rosa-sinensis mucilage (HRM) as disintegrants in the formulation. Central composite design (CCD) was applied to optimize the influence of three levels each of CCS ( X 1 ) and HRM ( X 2 ) concentrations (independent variables) for investigated responses: disintegration time (DT) ( Y 1 ), % friability ( F ) ( Y 2 ), and % cumulative drug release (DR) ( Y 3 ) (dependent variables). This face-centered second-order model's reliability was verified by the probability and adequate precision values from the analysis of variance, while the significant factor effects influencing the studied responses were identified using multiple linear regression analysis. Perturbation and response surface plots were interpreted to evaluate the responses' sensitivity towards the variables. During optimization, the concentrations of the processed factors were evaluated, and the resulting values were in good agreement with predicted estimates endorsing the validity. Spectral study by Fourier Transform Infrared Spectroscopy (FTIR) and thermograms from Differential Scanning Calorimetry (DSC) demonstrated the drug-excipients compatibility of the optimized formulation. The optimized formulation has concentrations of 9.05 mg and 16.04 mg of CCS and HRM each, respectively, and the model predicted DT of 13.271 sec, F of 0.498, and DR of 99.768%.

Taguchi design optimization of machining parameters on the CNC end milling process of halloysite nanotube with aluminium reinforced epoxy matrix (HNT/Al/Ep hybrid composite

Directory of Open Access Journals (Sweden)

J.S. Pang

2014-08-01

Full Text Available This paper introduces the application of Taguchi optimization methodology in optimizing the cutting parameters of end-milling process for machining the halloysite nanotubes (HNTs with aluminium reinforced epoxy hybrid composite material under dry condition. The machining parameters which are chosen to be evaluated in this study are the depth of cut (d, cutting speed (S and feed rate (f. While, the response factors to be measured are the surface roughness of the machined composite surface and the cutting force. An orthogonal array of the Taguchi method was set-up and used to analyse the effect of the milling parameters on the surface roughness and cutting force. The result from this study shows that the application of the Taguchi method can determine the best combination of machining parameters that can provide the optimal machining response conditions which are the lowest surface roughness and lowest cutting force value. For the best surface finish, A1–B3–C3 (d = 0.4 mm, S = 1500 rpm, f = 60 mmpm is found to be the optimized combination of levels for all the three control factors from the analysis. Meanwhile, the optimized combination of levels for all the three control factors from the analysis which provides the lowest cutting force was found to be A2–B2–C2 (d = 0.6 mm, S = 1000 rpm, f = 40 mmpm.

Optimizing Blendstock Composition and Ethanol Feedstock to Reduce Gasoline Well-to-Pump CO 2 Emission

KAUST Repository

Zhang, Bo; Sarathy, Mani; Abdul-Manan, Amir F.N.

2017-01-01

Lifecycle CO2 emission of ethanol blended gasoline was simulated to investigate how fuel properties and composition affect overall emission. Fuel research octane number (RON), octane sensitivity and ethanol content (derived from sugarcane and corn) were varied in the simulations to formulate blended fuels that economically achieve target specifications. The well-to-pump (WTP) simulation results were then analyzed to understand the effects of fuel composition on emission. Elevated ethanol content displaces aromatics and olefins required in gasoline blendstock to reach a target fuel specification. The addition of greater sugarcane-based ethanol percentage in constant aromatics and olefins fuel reduces its WTP CO2 emission. Corn-based ethanol blending does not offer CO2 emission offset due to its high production emissions. The mixing of sugarcane-based with corn-based ethanol is shown to be a potentially effective method for achieving a blended fuel with a lower lifecycle CO2 emission. Besides CO2 emission, the total greenhouse gas (GHG) emission from land-use conversions (LUC), CH4, and N2O are also significant in determining the optimal fuel blend. Herein, we present preliminary results showing that total GHG emissions significantly increase when either corn or sugarcane ethanol is blended at even small percentages; detailed results will be addressed in future communications.

Optimizing Blendstock Composition and Ethanol Feedstock to Reduce Gasoline Well-to-Pump CO 2 Emission

KAUST Repository

Zhang, Bo

2017-06-02

Lifecycle CO2 emission of ethanol blended gasoline was simulated to investigate how fuel properties and composition affect overall emission. Fuel research octane number (RON), octane sensitivity and ethanol content (derived from sugarcane and corn) were varied in the simulations to formulate blended fuels that economically achieve target specifications. The well-to-pump (WTP) simulation results were then analyzed to understand the effects of fuel composition on emission. Elevated ethanol content displaces aromatics and olefins required in gasoline blendstock to reach a target fuel specification. The addition of greater sugarcane-based ethanol percentage in constant aromatics and olefins fuel reduces its WTP CO2 emission. Corn-based ethanol blending does not offer CO2 emission offset due to its high production emissions. The mixing of sugarcane-based with corn-based ethanol is shown to be a potentially effective method for achieving a blended fuel with a lower lifecycle CO2 emission. Besides CO2 emission, the total greenhouse gas (GHG) emission from land-use conversions (LUC), CH4, and N2O are also significant in determining the optimal fuel blend. Herein, we present preliminary results showing that total GHG emissions significantly increase when either corn or sugarcane ethanol is blended at even small percentages; detailed results will be addressed in future communications.

Determination of optimal wet ethanol composition as a fuel in spark ignition engine

International Nuclear Information System (INIS)

Fagundez, J.L.S.; Sari, R.L.; Mayer, F.D.; Martins, M.E.S.; Salau, N.P.G.

2017-01-01

Highlights: • Batch distillation to produce HEF and fuel blends of wet ethanol. • Conversion efficiency of a SI engine operating with HEF and wet ethanol. • NEF as a new metric to calculate the energy efficiency of HEF and wet ethanol. • Optimal wet ethanol composition as a fuel in SI engine based on NEF. - Abstract: Studies are unanimous that the greatest fraction of the energy necessary to produce hydrous ethanol fuel (HEF), i.e. above 95%v/v of ethanol in water, is spent on water removal (distillation). Previous works have assessed the energy efficiency of HEF; but few, if any, have done the same for wet ethanol fuel (sub-azeotropic hydrous ethanol). Hence, a new metric called net energy factor (NEF) is proposed to calculate the energy efficiency of wet ethanol and HEF. NEF calculates the ratio of Lower Heating Value (LHV) derived from ethanol fuel, total energy out, to energy used to obtain ethanol fuel as distillate, total energy in. Distillation tests were performed batchwise to obtain as distillate HEF and four different fuel blends of wet ethanol with a range from 60%v/v to 90%v/v of ethanol and the amount of energy spent to distillate each ethanol fuel calculated. The efficiency parameters of a SI engine operating with the produced ethanol fuels was tested to calculate their respective conversion efficiency. The results of net energy factors show a clear advantage of wet ethanol fuels over HEF; the optimal efficiency was wet ethanol fuel with 70%v/v of ethanol.

Optimal Design of Composite Structures Under Manufacturing Constraints

DEFF Research Database (Denmark)

Marmaras, Konstantinos

determination of the appropriate laminate thickness and the material choice in the structure. The optimal design problems that arise are stated as nonconvex mixed integer programming problems. We resort to different reformulation techniques to state the optimization problems as either linear or nonlinear convex....... The continuous relaxation of the mixed integer programming problems is being solved by an implementation of a primal–dual interior point method for nonlinear programming that updates the barrier parameter adaptively. The method is chosen for its excellent convergence properties and the ability of the method...... design phase results in structures with better structural performance reducing the need of manually post–processing the found designs....

Optimal Topology and Experimental Evaluation of Piezoelectric Materials for Actively Shunted General Electric Polymer Matrix Fiber Composite Blades

Science.gov (United States)

Choi, Benjamin B.; Duffy, Kirsten; Kauffman, Jeffrey L.; Kray, Nicholas

2012-01-01

NASA Glenn Research Center, in collaboration with GE Aviation, has begun the development of a smart adaptive structure system with piezoelectric (PE) transducers to improve composite fan blade damping at resonances. Traditional resonant damping approaches may not be realistic for rotating frame applications such as engine blades. The limited space in which the blades reside in the engine makes it impossible to accommodate the circuit size required to implement passive resonant damping. Thus, a novel digital shunt scheme has been developed to replace the conventional electric passive shunt circuits. The digital shunt dissipates strain energy through the load resistor on a power amplifier. General Electric (GE) designed and fabricated a variety of polymer matrix fiber composite (PMFC) test specimens. Investigating the optimal topology of PE sensors and actuators for each test specimen has revealed the best PE transducer location for each target mode. Also a variety of flexible patches, which can conform to the blade surface, have been tested to identify the best performing PE patch. The active damping control achieved significant performance at target modes. This work has been highlighted by successful spin testing up to 5000 rpm of subscale GEnx composite blades in Glenn s Dynamic Spin Rig.

Optimal design of variable-stiffness fiber-reinforced composites using cellular automata

NARCIS (Netherlands)

Setoodeh, S.

2005-01-01

Growing number of applications of composites materials in aerospace and naval structures along with advancements in manufacturing technologies demand continuous innovations in design of composite structures. In the traditional design of composite laminates, fiber orientation angles are constant for

Optimization of Liposomal Lipid Composition for a New, Reactive Sulfur Donor, and In Vivo Efficacy Studies on Mice to Antagonize Cyanide Intoxication

Directory of Open Access Journals (Sweden)

Ilona Petrikovics

2011-01-01

Full Text Available Present studies have focused on a novel cyanide antidotal system, on the coencapsulation of a new sulfur donor DTO with rhodanese within sterically stabilized liposomes. The optimal lipid composition for coencapsulation of DTO with rhodanese is the combination of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, cholesterol, cationic lipid (DOTAP, and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol-2000] ammonium salt (with molar ratios of 82.7 : 9.2 : 3.0 : 5.1. With the optimized compositions, prophylactic and therapeutic in vivo efficacy studies were carried out in a mice model. When DTO was coencapsulated with rhodanese and thiosulfate the prophylactic antidotal protection was 4.9×LD50. Maximum antidotal protection against cyanide intoxication (15×LD50 was achieved with coencapsulated rhodanese and DTO/thiosulfate in combination with sodium nitrite. When applied therapeutically, 100% survival rate (6/6 was achieved at 20 mg/kg cyanide doses with the encapsulated DTO-rhodanese-thiosulfate antidotal systems with and without sodium nitrite. These data are indicating that the appropriately formulated DTO is a promising sulfur donor for cyanide antagonism.

Optimization of preparation conditions of polyamide thin film composite membrane for organic solvent nanofiltration

International Nuclear Information System (INIS)

Namvar-Mahboub, Mahdieh; Pakizeh, Majid

2014-01-01

Separation performance of polyamide composite membranes is affected by several parameters during formation of thin upper layer via interfacial polymerization. We investigated the effect of various polyamide synthesis conditions on the performance of organic solvent resistant polyamide composite membranes through the model equations designed by 2-level fractional factorial design. The dewaxing solvent recovery was selected as separation process. Five factors were changed in two level includin; TMC concentration (0.05-0.1%), MPD concentration (1-2%), support immersion time in organic solution (2-4 min), support immersion time in aqueous solution (1-2 min), and curing temperature (70-80 .deg. C). The resultant equations showed 93.48% and 94.82% of the variability (R 2 adj ) in data used to fit oil rejection and permeate flux models, respectively. The analysis of variance revealed that both models were high significant. It was also observed that TMC concentration, MPD concentration and immersion time in TMC have more pronounced effect on the oil rejection and permeate flux than other factors and interactions. Optimal polyamide preparation conditions were obtained using multiple response method for 94% oil rejection as target value. According to the results, the best value of permeate flux (8.86 l/(m 2 ·h)) was found at TMC concentration of 0.1%, MPD concentration of 1.94%, immersion time in TMC of 3.88 min, immersion time in MPD of 1.95 min and curing temperature of 71.96 .deg. C with desirability factor of 1

Combined Effect of Synthetic and Natural Polymers in Preparation of Cetirizine Hydrochloride Oral Disintegrating Tablets: Optimization by Central Composite Design

Directory of Open Access Journals (Sweden)

Chandra Sekhar Patro

2017-01-01

Full Text Available Our aim was to employ experimental design to formulate and optimize cetirizine hydrochloride oral disintegrating tablets (ODTs by direct compression technique, using the mutual effect of synthetic croscarmellose sodium (CCS and natural Hibiscus rosa-sinensis mucilage (HRM as disintegrants in the formulation. Central composite design (CCD was applied to optimize the influence of three levels each of CCS (X1 and HRM (X2 concentrations (independent variables for investigated responses: disintegration time (DT (Y1, % friability (F (Y2, and % cumulative drug release (DR (Y3 (dependent variables. This face-centered second-order model’s reliability was verified by the probability and adequate precision values from the analysis of variance, while the significant factor effects influencing the studied responses were identified using multiple linear regression analysis. Perturbation and response surface plots were interpreted to evaluate the responses’ sensitivity towards the variables. During optimization, the concentrations of the processed factors were evaluated, and the resulting values were in good agreement with predicted estimates endorsing the validity. Spectral study by Fourier Transform Infrared Spectroscopy (FTIR and thermograms from Differential Scanning Calorimetry (DSC demonstrated the drug-excipients compatibility of the optimized formulation. The optimized formulation has concentrations of 9.05 mg and 16.04 mg of CCS and HRM each, respectively, and the model predicted DT of 13.271 sec, F of 0.498, and DR of 99.768%.

Autoclave cycle optimization for high performance composite parts manufacturing

OpenAIRE

Nele, L.; Caggiano, A.; Teti, R.

2016-01-01

In aeronautical production, autoclave curing of composite parts must be performed according to a specified diagram of temperature and pressure vs time. Part-tool assembly thermal inertia and shape have a large influence on the heating and cooling rate, and therefore on the dwell time within the target temperature range. When simultaneously curing diverse composite parts, the total autoclave cycle time is driven by the part-tool assembly with the lower heating and cooling rates. With the aim t...

The Brittleness and Chemical Stability of Optimized Geopolymer Composites

Czech Academy of Sciences Publication Activity Database

Steinerová, Michaela; Matulová, Lenka; Vermach, P.; Kotas, J.

2017-01-01

Roč. 10, č. 4 (2017), č. článku 396. ISSN 1996-1944 R&D Projects: GA ČR GPP104/12/P477 Institutional support: RVO:67985891 Keywords : metakaolin * interfacial transition zone * compressive * flexural strength * elastic modulus * impact strength * acid leaching * porosity Subject RIV: JI - Composite Materials OBOR OECD: Composites (including laminates, reinforced plastics, cermets, combined natural and synthetic fibre fabrics Impact factor: 2.654, year: 2016 http://www.mdpi.com/1996-1944/10/4/396

Quasiconvex optimization and location theory

CERN Document Server

Santos Gromicho, Jaoquim António

1998-01-01

grams of which the objective is given by the ratio of a convex by a positive (over a convex domain) concave function. As observed by Sniedovich (Ref. [102, 103]) most of the properties of fractional pro­ grams could be found in other programs, given that the objective function could be written as a particular composition of functions. He called this new field C­ programming, standing for composite concave programming. In his seminal book on dynamic programming (Ref. [104]), Sniedovich shows how the study of such com­ positions can help tackling non-separable dynamic programs that otherwise would defeat solution. Barros and Frenk (Ref. [9]) developed a cutting plane algorithm capable of optimizing C-programs. More recently, this algorithm has been used by Carrizosa and Plastria to solve a global optimization problem in facility location (Ref. [16]). The distinction between global optimization problems (Ref. [54]) and generalized convex problems can sometimes be hard to establish. That is exactly the reason ...

Buckling optimization of steering stiffeners for grid-stiffened composite structures

NARCIS (Netherlands)

Wang, D.; Abdalla, M.M.

2015-01-01

Grid-stiffened composite structures, where the skin is stiffened by a lattice of stiffeners, not only allow for significant reduction in structural weight but are also competitive in terms of structural stability and damage tolerance compared with sandwich composite structures. As the development of

Enhanced index tracking modelling in portfolio optimization

Science.gov (United States)

Lam, W. S.; Hj. Jaaman, Saiful Hafizah; Ismail, Hamizun bin

2013-09-01

Enhanced index tracking is a popular form of passive fund management in stock market. It is a dual-objective optimization problem, a trade-off between maximizing the mean return and minimizing the risk. Enhanced index tracking aims to generate excess return over the return achieved by the index without purchasing all of the stocks that make up the index by establishing an optimal portfolio. The objective of this study is to determine the optimal portfolio composition and performance by using weighted model in enhanced index tracking. Weighted model focuses on the trade-off between the excess return and the risk. The results of this study show that the optimal portfolio for the weighted model is able to outperform the Malaysia market index which is Kuala Lumpur Composite Index because of higher mean return and lower risk without purchasing all the stocks in the market index.

Polyaspartate extraction of cadmium ions from contaminated soil: Evaluation and optimization using central composite design.

Science.gov (United States)

Mu'azu, Nuhu Dalhat; Haladu, Shamsuddeen A; Jarrah, Nabeel; Zubair, Mukarram; Essa, Mohammad H; Ali, Shaikh A

2018-01-15

The occurrences of heavy metal contaminated sites and soils and the need for devising environmentally friendly solutions have become global issues of serious concern. In this study, polyaspartate (a highly biodegradable agent) was synthesized using L-Aspartic acid via a new modified thermal procedure and employed for extraction of cadmium ions (Cd) from contaminated soil. Response surface methodology approach using 3 5 full faced centered central composite design was employed for modeling, evaluating and optimizing the influence of polyaspartate concentration (36-145mM), polyaspartate/soil ratio (5-25), initial heavy metal concentration (100-500mg/kg), initial pH (3-6) and extraction time (6-24h) on Cd ions extracted into the polyaspartate solution and its residual concentration in the treated soil. The Cd extraction efficacy obtained reached up to 98.8%. Increase in Cd extraction efficiency was associated with increase in the polyaspartate and Cd concentration coupled with lower polyaspertate/soil ratio and initial pH. Under the optimal conditions characterized with minimal utilization of the polyaspartate and high Cd ions removal, the extractible Cd in the polyaspartate solution reached up to 84.4mg/L which yielded 85% Cd extraction efficacy. This study demonstrates the suitability of using polyaspartate as an effective environmentally friendly chelating agent for Cd extraction from contaminated soils. Copyright © 2017 Elsevier B.V. All rights reserved.

Optimization of Ligninolytic Enzyme Activity and Production Rate with Ceriporiopsis subvermispora for Application in Bioremediation by Varying Submerged Media Composition and Growth Immobilization Support

Directory of Open Access Journals (Sweden)

Janja Babič

2012-09-01

Full Text Available Response surface methodology (central composite design of experiments was employed to simultaneously optimize enzyme production and productivities of two ligninolytic enzymes produced by Ceriporiopsis subvermispora. Concentrations of glucose, ammonium tartrate and Polysorbate 80 were varied to establish the optimal composition of liquid media (OLM, where the highest experimentally obtained activities and productivities were 41 U L−1 and 16 U L−1 day−1 for laccase (Lac, and 193 U L−1 and 80 U L−1 day−1 for manganese peroxidase (MnP. Considering culture growth in OLM on various types of immobilization support, the best results were obtained with 1 cm beech wood cubes (BWCM. Enzyme activities in culture filtrate were 152 U L−1 for Lac and 58 U L−1 for MnP, since the chemical composition of this immobilization material induced higher Lac activity. Lower enzyme activities were obtained with polyurethane foam. Culture filtrates of OLM and BWCM were applied for dye decolorization. Remazol Brilliant Blue R (RBBR was decolorized faster and more efficiently than Copper(IIphthalocyanine (CuP with BWCM (80% and 60%, since Lac played a crucial role. Decolorization of CuP was initially faster than that of RBBR, due to higher MnP activities in OLM. The extent of decolorization after 14 h was 60% for both dyes.

Design optimization of multi-layer Silicon Carbide cladding for light water reactors

Energy Technology Data Exchange (ETDEWEB)

Lee, Youho, E-mail: euo@unm.edu [Department of Nuclear Engineering, University of New Mexico, MSC01 1120 1 University of New Mexico, Albuquerque, NM 87131 (United States); NO, Hee Cheon, E-mail: hcno@kaist.ac.kr [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Lee, Jeong Ik, E-mail: jeongiklee@kaist.ac.kr [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

2017-01-15

Highlights: • SiC cladding designs are optimized with a multi-layer structural analysis code. • Layer radial thickness fraction that minimizes cladding fracture probability exists. • The demonstrated procedure is applicable for multi-layer SiC cladding design. • Duplex SiC with the inner composite fraction ∼0.4 is optimal in a reference case. • Increasing composite thermal conductivity markedly decreases SiC cladding stress. - Abstract: A parametric study that demonstrates a methodology for determining the optimum bilayer composition in a duplex SiC cladding is discussed. The structural performance of multi-layer SiC cladding design is significantly affected by radial thickness fraction of each layer. This study shows that there exists an optimal composite/monolith radial thickness fraction that minimizes failure probability for a duplex SiC cladding in steady-state operation. An exemplary reference case study shows that the duplex cladding with the inner composite fraction ∼0.4 and the outer CVD-SiC fraction ∼0.6 is found to be the optimal SiC cladding design for the current PWRs with the reference material choice for CVD-SiC and fiber reinforced composite. A marginal increase in the composite fraction from the presented optimal designs may lead to increase structural integrity by introducing some unquantified merits such as increasing damage tolerance. The major factors that affect the optimum cladding designs are temperature gradients and internal gas pressure. Clad wall thickness, thermal conductivity, and Weibull modulus are among the key design parameters/material properties.

A mineralogical and granulometric study of Cayambe volcano debris avalanche deposit

Science.gov (United States)

Detienne, M.; Delmelle, P.; Guevara, A.; Samaniego, P.; Bustillos, J.; Sonnet, P.; Opfergelt, S.

2013-12-01

Volcano flank/sector collapse represents one of the most catastrophic volcanic hazards. Various volcanic and non-volcanic processes are known to decrease the stability of a volcanic cone, eventually precipitating its gravitational failure. Among them, hydrothermal alteration of volcanic rocks leading to clay mineral formation is recognized as having a large negative impact on rock strength properties. Furthermore, the presence of hydrothermal clays in the collapsing mass influences the behavior of the associated volcanic debris avalanche. In particular, clay-containing debris avalanches seem to travel farther and spread more widely than avalanches of similar volume but which do not incorporate hydrothermally-altered materials. However, the relationship between hydrothermal alteration, flank collapse and debris avalanche behavior is not well understood. The objective of this study is to better determine the volume and composition of hydrothermal clay minerals in the poorly characterized debris avalanche deposit (DAD) of Cayambe composite volcano, located in a densely populated area ~70 km northeast of Quito, Ecuador. Cayambe DAD originated from a sector collapse, which occurred less than 200 ka ago. The DAD is 10-20 m thick and has an estimated total volume of ~0.85 Km3. The H/L ratio (where H is the vertical drop and L is the travel distance of the avalanche) for Cayambe DAD is ~0.095, suggesting a high mobility. In the medial-distal zone, at 9-20 km from its source, the DAD consists of an unstratified and unsorted matrix supporting millimetric to metric clasts. It has a matrix facies (i.e. rich in particles DAD behaved as a cohesive debris flow. Analysis of 13 matrix samples reveals a large variability in particle size distribution. This may reflect poor mixing of the collapsed material during transport. The clay fraction content in the matrix ranges from 15 to 30 wt.%, and does not show a relationship with the sample position in the DAD. Mineralogical

Optimized chemical composition, working and heat treatment condition for resistance to irradiation assisted stress corrosion cracking of cold worked 316 and high-chromium austenitic stainless steel

International Nuclear Information System (INIS)

Yonezawa, Toshio; Iwamura, Toshihiko; Fujimoto, Koji; Ajiki, Kazuhide

2000-01-01

The authors have reported that the primary water stress corrosion cracking (PWSCC) in baffle former bolts made of austenitic stainless steels for PWR after long-term operation is caused by irradiation-induced grain boundary segregation. The resistance to PWSCC of simulated austenitic stainless steels whose chemical compositions are simulated to the grain boundary chemical composition of 316 stainless steel after irradiation increased with decrease of the silicon content, increases of the chromium content, and precipitation of M 23 C 6 carbides at the grain boundaries. In order to develop resistance to irradiation assisted stress corrosion cracking in austenitic stainless steels, optimized chemical compositions and heat treatment conditions for 316CW and high-chromium austenitic stainless steels for PWR baffle former bolts were investigated. For 316CW stainless steel, ultra-low-impurities and high-chromium content are beneficial. About 20% cold working before aging and after solution treatment has also been recommended to recover sensitization and make M 23 C 6 carbides coherent with the matrix at the grain boundaries. Heating at 700 to 725degC for 20 to 50 h was selected as a suitable aging procedure. Cold working of 5 to 10% after aging produced the required mechanical properties. The optimized composition of the high-chromium austenitic stainless steel contents 30% chromium, 30% nickel, and ultra-low impurity levels. This composition also reduces the difference between its thermal expansion coefficient and that of 304 stainless steel for baffle plates. Aging at 700 to 725degC for longer than 40 h and cold working of 10 to 15% after aging were selected to meet mechanical property specifications. (author)

Optimization of Mineral Separator for Recovery of Total Heavy Minerals of Bay of Bengal using Central Composite Design

Science.gov (United States)

Routray, Sunita; Swain, Ranjita; Rao, Raghupatruni Bhima

2017-04-01

The present study is aimed at investigating the optimization of a mineral separator for processing of beach sand minerals of Bay of Bengal along Ganjam-Rushikulya coast. The central composite design matrix and response surface methodology were applied in designing the experiments to evaluate the interactive effects of the three most important operating variables, such as feed quantity, wash water rate and Shake amplitude of the deck. The predicted values were found to be in good agreement with the experimental values (R2 = 0.97 for grade and 0.98 for recovery). To understand the impact of each variable, three dimensional (3D) plots were also developed for the estimated responses.

Optimization of Process Parameters During Drilling of Glass-Fiber Polyester Reinforced Composites Using DOE and ANOVA

Directory of Open Access Journals (Sweden)

N.S. Mohan

2010-09-01

Full Text Available Polymer-based composite material possesses superior properties such as high strength-to-weight ratio, stiffness-to-weight ratio and good corrosive resistance and therefore, is attractive for high performance applications such as in aerospace, defense and sport goods industries. Drilling is one of the indispensable methods for building products with composite panels. Surface quality and dimensional accuracy play an important role in the performance of a machined component. In machining processes, however, the quality of the component is greatly influenced by the cutting conditions, tool geometry, tool material, machining process, chip formation, work piece material, tool wear and vibration during cutting. Drilling tests were conducted on glass fiber reinforced plastic composite [GFRP] laminates using an instrumented CNC milling center. A series of experiments are conducted using TRIAC VMC CNC machining center to correlate the cutting parameters and material parameters on the cutting thrust, torque and surface roughness. The measured results were collected and analyzed with the help of the commercial software packages MINITAB14 and Taly Profile. The surface roughness of the drilled holes was measured using Rank Taylor Hobson Surtronic 3+ instrument. The method could be useful in predicting thrust, torque and surface roughness parameters as a function of process variables. The main objective is to optimize the process parameters to achieve low cutting thrust, torque and good surface roughness. From the analysis it is evident that among all the significant parameters, speed and drill size have significant influence cutting thrust and drill size and specimen thickness on the torque and surface roughness. It was also found that feed rate does not have significant influence on the characteristic output of the drilling process.

Amorphous metal matrix composite ribbons

International Nuclear Information System (INIS)

Barczy, P.; Szigeti, F.

1998-01-01

Composite ribbons with amorphous matrix and ceramic (SiC, WC, MoB) particles were produced by modified planar melt flow casting methods. Weldability, abrasive wear and wood sanding examinations were carried out in order to find optimal material and technology for elevated wear resistance and sanding durability. The correlation between structure and composite properties is discussed. (author)

ENERGY SAVING RESERVES IN THE PRODUCTION OF FEED ADDITIVES WITH THE SPECIFIED GRANULOMETRIC COMPOSITION

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A. A. Shevtsov

2015-01-01

Full Text Available Due to the growing need to substitute expensive foreign-made feed products need for expanding food resources in the Russian market appears. The disadvantages of existing technological lines for the preparation of mineral feed additives are high specific energy consumption, low economic efficiency and inadequate conditions for environmental safety insuring. That is why energy-efficient production method for the feed additive based on zeolite and a technological line for its realization was developed at the Department of Technology of bread, pastry, pasta and grain processing industries in VSUET. Application of refrigeration unit operating in heat pump mode allows preparation of heat transfer agents with a maximum utilization of secondary heat sources. After drying the spent drying agent is fed to the preheating methioninate copper suspension through the regenerative heat exchange, then to the dehumidification into the evaporator of refrigeration unit and then it is returned to the first section of the two-part condenser in closed-loop mode. Feed fat is heated to 55 ... 60 ° C, by "hot water", heating of which takes place in the second section of the 11th condenser to the temperature of 70 ... 75 ° C and is fed into the jacket of fat melting device. Then it is returned to the second capacitor section to form a recirculation loop. We developed a feed additive with the following particle size distribution: a large fraction of 2.8%, the average fraction of 95.2%, the fine fraction of 2.0%, the residue on the sieve with a mesh № 1,2 of 2,0%, with a moisture content of 6.2%, the angle of repose of 42 deg., dispersibility of 6.9%, a bulk density of 385 kg / m3. The proposed method for the production of the feed additive based on zeolite ensures environmental safety of production due to closed recirculation circuits on material and energy flows, helps to reduce energy and resource consumption for the production of the feed additive, to obtain high quality product with high uniformity and low moisture content.

HYDRAULIC CONCRETE COMPOSITION AND PROPERTIES CONTROL SYSTEM

Directory of Open Access Journals (Sweden)

O. M. Pshinko

2015-08-01

Full Text Available Purpose. Scientific work aims at the development and testing of information system to meet the challenges of concrete composition design and control (for railway structures and buildings based on the physico-analytical method algorithm for hydraulic concrete composition calculation. Methodology. The proposed algorithm of hydraulic concrete composition calculation is based on the physicochemical mechanics and in particular on the rheology of elastic–viscous–plastic bodies. The system of canonical equations consists of the equations for concrete strength, absolute volume, concrete mix consistency as well as the equation for optimal concrete saturation with aggregates while minimizing cement content. The joint solution of these four equations related to composition allows determining for the materials the concrete composition of required strength, concrete workability with minimum cement content. The procedure for calculation of hydraulic concrete composition according to the physico-analytical method consists of two parts: 1 physical, which is laboratory testing of concrete mix components in different concrete compositions; 2 analytical, which represents the calculation algorithm for concrete compositions equivalent in concrete strength and workability that comply with the specific conditions of concrete placing. Findings. To solve the problem of designing the concrete composition with the desired properties for railway structures and buildings it was proposed to use the information technology in the form of a developed computer program whose algorithm includes the physico-analytical method for hydraulic concrete composition determination. Originality. The developed concrete composition design method takes into account the basic properties of raw materials, concrete mix and concrete, which are pre-determined. The distinctive feature of physico-analytical method is obtaining of a set of equivalent compositions with a certain concrete mix

Depositional environment of the Gombe Formation in the Gongola ...

African Journals Online (AJOL)

The depositional environment of the Gombe Formation was determined using grain size parameters in which sixteen sandstone samples and ninety nine pebbles were subjected to granulometric and pebbles morphometric analysis respectively. The granulometric analysis for the sixteen (16) samples of the Gombe ...

Optimization of sulfamethoxazole degradation by TiO2/hydroxyapatite composite under ultraviolet irradiation using response surface methodology

International Nuclear Information System (INIS)

Chun, Suk Young; Kim, Ji Tae; Chang, Soon Woong; An, Sang Woo; Lee, Si Jin

2014-01-01

A titanium dioxide/hydroxyapatite/ultraviolet (TiO 2 /HAP/UV-A) system was used to remove sulfamethoxazole (SMX) from water in a second-order response surface methodology (RSM) experiment with a three-level Box-Behnken design (BBD) for optimization. The effects of both the primary and secondary interaction effects of three photocatalytic reaction variables were examined: the concentration of SMX (X 1 ), dose of TiO 2 /HAP composite (X 2 ), and UV intensity (X 3 ). The UV intensity and TiO 2 /HAP dose significantly influence the SMX and total organic carbon (TOC) removal (p<0.001). However, the SMX and TOC removal are enhanced with increasing TiO 2 /HAP dose up to certain levels, and further increases in the TiO 2 /HAP dose result in adverse effects due to hydroxyl radical scavenging at higher catalyst concentrations. Complete removal of SMX was achieved upon UV-A irradiation for 180 min. Under optimal conditions, 51.2% of the TOC was removed, indicating the formation of intermediate products during SMX degradation. The optimal ratio of SMX (mg L -1 ) to TiO 2 /HAP (g L -1 ) to UV (W/L) was 5.4145 mg L -1 to 1.4351 g L -1 to 18 W for both SMX and TOC removal. By comparison with actual applications, the experimental results were found to be in good agreement with the model's predictions, with mean results for SMX and TOC removal of 99.89% and 51.01%, respectively

Optimization of Polymer-ECM Composite Scaffolds for Tissue Engineering: Effect of Cells and Culture Conditions on Polymeric Nanofiber Mats

Directory of Open Access Journals (Sweden)

Ritu Goyal

2017-01-01

Full Text Available The design of composite tissue scaffolds containing an extracellular matrix (ECM and synthetic polymer fibers is a new approach to create bioactive scaffolds that can enhance cell function. Currently, studies investigating the effects of ECM-deposition and decellularization on polymer degradation are still lacking, as are data on optimizing the stability of the ECM-containing composite scaffolds during prolonged cell culture. In this study, we develop fibrous scaffolds using three polymer compositions, representing slow (E0000, medium (E0500, and fast (E1000 degrading materials, to investigate the stability, degradation, and mechanics of the scaffolds during ECM deposition and decellularization, and during the complete cellularization-decell-recell cycle. We report data on percent molecular weight (% Mw retention of polymeric fiber mats, changes in scaffold stiffness, ECM deposition, and the presence of fibronectin after decellularization. We concluded that the fast degrading E1000 (Mw retention ≤ 50% after 28 days was not sufficiently stable to allow scaffold handling after 28 days in culture, while the slow degradation of E0000 (Mw retention ≥ 80% in 28 days did not allow deposited ECM to replace the polymer support. The scaffolds made from medium degrading E0500 (Mw retention about 60% at 28 days allowed the gradual replacement of the polymer network with cell-derived ECM while maintaining the polymer network support. Thus, polymers with an intermediate rate of degradation, maintaining good scaffold handling properties after 28 days in culture, seem best suited for creating ECM-polymer composite scaffolds.

Reinforced magnesium composites by metallic particles for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Vahid, Alireza; Hodgson, Peter [Institute for Frontier Materials, Deakin University, Geelong, Victoria 3217 (Australia); Li, Yuncang, E-mail: yuncang.li@rmit.edu.au [Institute for Frontier Materials, Deakin University, Geelong, Victoria 3217 (Australia); School of Engineering, RMIT University, Melbourne, Victoria 3001 (Australia)

2017-02-08

Pure magnesium (Mg) implants have unsatisfactory mechanical properties, particularly in loadbearing applications. Particulate-reinforced Mg composites are known as promising materials to provide higher strength implants compared to unreinforced metals. In the current work biocompatible niobium (Nb) and tantalum (Ta) particles are selected as reinforcement, and Mg-Nb and Mg-Ta composites fabricated via a powder metallurgy process associated with the ball milling technique. The effect of Nb and Ta contents on the microstructure and mechanical properties of Mg matrix was investigated. There was a uniform distribution of reinforcements in the Mg matrix with reasonable integrity and no intermetallic formation. The compressive mechanical properties of composites vary with reinforcement contents. The optimal parameters to fabricate biocompatible Mg composites and the optimal composition with appropriate strength, hardness and ductility are recommended.

Optimization and characterization of woven kevlar reinforced epoxy matrix composite materials

International Nuclear Information System (INIS)

Imran, A.; Aslam, S.

2007-01-01

Composite materials are actually well established materials that have demonstrated their promising advantages among the light weight structural materials used for aerospace and advanced applications. An effort is now being made to develop and characterize the Kevlar Epoxy Composite Materials by changing the vol. fraction of Kevlar in epoxy matrix. The optimum characteristics were observed with 37% fiber with resin by applying hand-lay-up process. The composites produced were subjected to mechanical testing to evaluate the mechanical characteristics. (author)

Pressurized fluid extraction of essential oil from Lavandula hybrida using a modified supercritical fluid extractor and a central composite design for optimization.

Science.gov (United States)

Kamali, Hossein; Jalilvand, Mohammad Reza; Aminimoghadamfarouj, Noushin

2012-06-01

Essential oil components were extracted from lavandin (Lavandula hybrida) flowers using pressurized fluid extraction. A central composite design was used to optimize the effective extraction variables. The chemical composition of extracted samples was analyzed by a gas chromatograph-flame ionization detector column. For achieving 100% extraction yield, the temperature, pressure, extraction time, and the solvent flow rate were adjusted at 90.6°C, 63 bar, 30.4 min, and 0.2 mL/min, respectively. The results showed that pressurized fluid extraction is a practical technique for separation of constituents such as 1,8-cineole (8.1%), linalool (34.1%), linalyl acetate (30.5%), and camphor (7.3%) from lavandin to be applied in the food, fragrance, pharmaceutical, and natural biocides industries. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimum culture medium composition for lipopeptide production by ...

Indian Academy of Sciences (India)

the media compositions so as to enhance the productivity of lipopeptide. The optimized media by ... provides greater insight in studying the impact of potential variables affecting the ... ing more flexible solutions than the classical optimization techniques. To the ... Hence, in this work, it is proposed to optimize the lipopeptide ...

Portfolio optimization with skewness and kurtosis

Science.gov (United States)

Lam, Weng Hoe; Jaaman, Saiful Hafizah Hj.; Isa, Zaidi

2013-04-01

Mean and variance of return distributions are two important parameters of the mean-variance model in portfolio optimization. However, the mean-variance model will become inadequate if the returns of assets are not normally distributed. Therefore, higher moments such as skewness and kurtosis cannot be ignored. Risk averse investors prefer portfolios with high skewness and low kurtosis so that the probability of getting negative rates of return will be reduced. The objective of this study is to compare the portfolio compositions as well as performances between the mean-variance model and mean-variance-skewness-kurtosis model by using the polynomial goal programming approach. The results show that the incorporation of skewness and kurtosis will change the optimal portfolio compositions. The mean-variance-skewness-kurtosis model outperforms the mean-variance model because the mean-variance-skewness-kurtosis model takes skewness and kurtosis into consideration. Therefore, the mean-variance-skewness-kurtosis model is more appropriate for the investors of Malaysia in portfolio optimization.

Central composite design approach towards optimization of flamboyant pods derived steam activated carbon for its use as heterogeneous catalyst in transesterification of Hevea brasiliensis oil

International Nuclear Information System (INIS)

Dhawane, Sumit H.; Kumar, Tarkeshwar; Halder, Gopinath

2015-01-01

Highlights: • Activated carbon was prepared from novel precursor flamboyant pods (Delonix regia). • Activation process was optimized using central composite design approach. • Prepared activated carbon at optimized condition was used as support for KOH. • Carbon based heterogeneous catalyst was used in transesterification of HBO. • Effect of catalyst loading and alcohol ratio on biodiesel yield was studied. - Abstract: The present investigation emphasises the preparation of carbon based KOH impregnated heterogeneous catalyst from flamboyant pods (Delonix regia) for the production of biodiesel from novel feedstock Hevea brasiliensis oil (HBO). Initially, carbonized char was physically activated by superheated steam and the process was optimized to study the effects of activation time and temperature by central composite design approach (CCD) using response surface methodology (RSM). Activated carbon was impregnated with KOH at four different ratios. Biodiesel production process was carried out at constant temperature 60 °C, reaction time 1 h, and 5 g of carbon based catalyst at varying quantities of catalyst loading (0.5, 2, 3.5, 5 wt%) and methanol to oil ratio (5:1–20:1). The influence of parameters on the biodiesel yield at varied condition was studied. Maximum yield of 89.3% was obtained at methanol to oil ratio 15:1 and catalyst loading 3.5 wt% and corresponding yield at same process parameters was observed to be 88.7% implying the significant activity of catalyst in reutilization. Produced biodiesel was characterized following ASTM standards. The experimental analysis confirmed that the carbonaceous catalyst developed from flamboyant pods under optimized condition is capable of transesterifying HBO into biodiesel

Design of materials with extreme thermal expansion using a three-phase topology optimization method

DEFF Research Database (Denmark)

Sigmund, Ole; Torquato, S.

1997-01-01

We show how composites with extremal or unusual thermal expansion coefficients can be designed using a numerical topology optimization method. The composites are composed of two different material phases and void. The optimization method is illustrated by designing materials having maximum therma...

Strategic vehicle fleet management - the composition problem

Directory of Open Access Journals (Sweden)

Adam Redmer

2015-03-01

Full Text Available Background: Fleets constitute the most important production means in transportation. Their appropriate management is crucial for all companies having transportation duties. The paper is the second one of a series of three papers that the author dedicates to the strategic vehicle fleet management topic. Material and methods: The paper discusses ways of building companies' fleets of vehicles. It means deciding on the number of vehicles in a fleet (the fleet sizing problem - FS and types of vehicles in a fleet (the fleet composition problem - FC. The essence of both problems lies in balancing transportation supply and demand taking into account different demand types to be fulfilled and different vehicle types that can be put into a fleet. Vehicles, which can substitute each other while fulfilling different demand types. In the paper an original mathematical model (an optimization method allowing for the FS/FC analysis is proposed. Results: An application of the proposed optimization method in a real-life decision situation (the case study within the Polish environment and the obtained solution are presented. The solution shows that there exist some best fitted (optimal fleet size / composition matching company's transportation requirements. An optimal fleet size / composition allows for a significantly higher fleet utilization (10-15% higher than any other, including random fleet structure. Moreover, any changes in the optimal fleet size / composition, even small ones, result in a lower utilization of vehicles (lower by a few percent. Conclusions: The presented in this paper analysis, on the one hand, is consistent with a widespread opinion that the number of vehicle types in a fleet should be limited. In the other words it means that the versatility / interchangeability of vehicles is very important. On the other hand, the analysis proves that even small changes in a fleet size / fleet composition can result in an important changes of the fleet

Machine Learning Optimization of Evolvable Artificial Cells

DEFF Research Database (Denmark)

Caschera, F.; Rasmussen, S.; Hanczyc, M.

2011-01-01

can be explored. A machine learning approach (Evo-DoE) could be applied to explore this experimental space and define optimal interactions according to a specific fitness function. Herein an implementation of an evolutionary design of experiments to optimize chemical and biochemical systems based...... on a machine learning process is presented. The optimization proceeds over generations of experiments in iterative loop until optimal compositions are discovered. The fitness function is experimentally measured every time the loop is closed. Two examples of complex systems, namely a liposomal drug formulation...

Extraction optimization and characterization of polysaccharide ...

African Journals Online (AJOL)

Keywords: Pinellia rhizoma, Polysaccharides Optimization extraction, Monosaccharide composition,. Antioxidant ..... mean yield of PRP was 2.47 %. Therefore ... Table 3: Analysis of variance (ANOVA) for the fitted quadratic polynomial model.

One new route to optimize the oxidation resistance of TiC/hastelloy (Ni-based alloy) composites applied for intermediate temperature solid oxide fuel cell interconnect by increasing graphite particle size

Science.gov (United States)

Qi, Qian; Liu, Yan; Wang, Lujie; Zhang, Hui; Huang, Jian; Huang, Zhengren

2017-09-01

TiC/hastelloy composites with suitable thermal expansion and excellent electrical conductivity are promising candidates for IT-SOFC interconnect. In this paper, the TiC/hastelloy composites are fabricated by in-situ reactive infiltration, and the oxidation resistance of composites is optimized by increasing graphite particle size. Results show that the increase of graphite particles size from 1 μm to 40 μm reduces TiC particle size from 2.68 μm to 2.22 μm by affecting the formation process of TiC. Moreover, the decrease of TiC particles size accelerates the fast formation of dense and continuous TiO2/Cr2O3 oxide layer, which bring down the mass gain (800 °C/100 h) from 2.03 mg cm-2 to 1.18 mg cm-2. Meanwhile, the coefficient of thermal expansion decreases from 11.15 × 10-6 °C-1 to 10.80 × 10-6 °C-1, and electrical conductivity maintains about 5800 S cm-1 at 800 °C. Therefore, the decrease of graphite particle size is one simple and effective route to optimize the oxidation resistance of composites, and meantime keeps suitable thermal expansion and good electrical conductivity.

[Optimization of SFE-CO2 Extraction for Ursolic Acid from Punica granatum Peel by Plackett-Burman and Central Composite Design].

Science.gov (United States)

Wang, Zhan-yi; Jin, Mei-hua; Wang, Yu-hai; Zhang, Li-hua; Bi, Hai-dan; Li, Zhuo-wa

2015-03-01

The optimum extraction of ursolic acid from Punica granatum peel by SFE-CO2 was investigated. Based on the design of Plackett-Burman(PB), significant factors influencing the yield of ursolic acid in the operation process were filtered, with the extraction rate of ursolic acid as the index. The results obtained by steepest ascent method approximated the maximum area of ursolic acid yield. Then the Central Composite Design(CCD) design was used to carry on the response surface optimization of significant factors, getting a two order mathematical model affecting the ursolic acid yield, as well as the optimum process conditions. The best technological conditions of the extraction of ursolic acid from Punica granatum peel by SFE-CO2 were that the extraction temperature was 46. 29 °C, extraction time was 91. 6 min and the extraction pressure was 34. 49 MPa. Under the optimal conditions, verification test of ursolic acid yield was 12. 508 mg/g, approximating to the predicted value of 12. 645 mg/g. The PB test and CCD test design are combined to optimize the extraction process of ursolic acid from Punica granatum peel by SFE-CO2. The screening results are statistically significant and the process operation is feasible.

Multi-variable optimization of PEMFC cathodes using an agglomerate model

Energy Technology Data Exchange (ETDEWEB)

Secanell, M.; Suleman, A.; Djilali, N. [Institute for Integrated Energy Systems and Department Mechanical Engineering, University of Victoria, PO Box 3055 STN CSC, Victoria, BC (Canada); Karan, K. [Queen' s-RMC Fuel Cell Research Centre and Department Chemical Engineering, Queen' s University, Kingston, Ont. (Canada)

2007-06-30

A comprehensive numerical framework for cathode electrode design is presented and applied to predict the catalyst layer and the gas diffusion layer parameters that lead to an optimal electrode performance at different operating conditions. The design and optimization framework couples an agglomerate cathode catalyst layer model to a numerical gradient-based optimization algorithm. The set of optimal parameters is obtained by solving a multi-variable optimization problem. The parameters are the catalyst layer platinum loading, platinum to carbon ratio, amount of electrolyte in the agglomerate and the gas diffusion layer porosity. The results show that the optimal catalyst layer composition and gas diffusion layer porosity depend on operating conditions. At low current densities, performance is mainly improved by increasing platinum loading to values above 1 mg cm{sup -2}, moderate values of electrolyte volume fraction, 0.5, and low porosity, 0.1. At higher current densities, performance is improved by reducing the platinum loading to values below 0.35 mg cm{sup -2} and increasing both electrolyte volume fraction, 0.55, and porosity 0.32. The underlying improvements due to the optimized compositions are analyzed in terms of the spatial distribution of the various overpotentials, and the effect of the agglomerate structure parameters (radius and electrolyte film) are investigated. The paper closes with a discussion of the optimized composition obtained in this study in the context of available experimental data. The analysis suggests that reducing the solid phase volume fraction inside the catalyst layer might lead to improved electrode performance. (author)

3.4. Durability of soil-cement mixtures influenced by hostile environment

International Nuclear Information System (INIS)

Saidov, D.Kh.

2011-01-01

It is determined that soil-cement mixture is one of most perspective materials, that can substitute concrete. Experiments on revelation of magnesium sulphate influence on soil-cement mixtures were carried out. Data on granulometric composition and physical parameters of loess soils is presented in this article. Portland cement M 400 was used as binder. According to the results it is concluded that stability of soil-cement mixtures from loess soils in solutions of magnesium sulphate depends on concentration of solution.

Plasma spheroidization and cladding of powders

Energy Technology Data Exchange (ETDEWEB)

Petrunichev, V.A.; Averin, V.V.; Sorokin, L.M.; Koroleva, E.B.

1987-02-01

With reference to experimental results for nickel and chromium alloys, it is shown that complex alloy powders can be spheroidized in plasma discharges using an argon plasma with hydrogen. The spheroidizing process is accompanied by the reduction of surface oxides, with uniform element distribution within the particles; the granulometric composition of the particles is preserved. It is also shown that plasma technology can be used for producing metal-clad oxide and carbide powders, which improve the performance of cermets and coatings.

Optimal Weighting for Exam Composition

Directory of Open Access Journals (Sweden)

Sam Ganzfried

2018-03-01

Full Text Available A problem faced by many instructors is that of designing exams that accurately assess the abilities of the students. Typically, these exams are prepared several days in advance, and generic question scores are used based on rough approximation of the question difficulty and length. For example, for a recent class taught by the author, there were 30 multiple choice questions worth 3 points, 15 true/false with explanation questions worth 4 points, and 5 analytical exercises worth 10 points. We describe a novel framework where algorithms from machine learning are used to modify the exam question weights in order to optimize the exam scores, using the overall final score as a proxy for a student’s true ability. We show that significant error reduction can be obtained by our approach over standard weighting schemes, i.e., for the final and midterm exam, the mean absolute error for prediction decreases by 90.58% and 97.70% for linear regression approach respectively resulting in better estimation. We make several new observations regarding the properties of the “good” and “bad” exam questions that can have impact on the design of improved future evaluation methods.

Bamboo-inspired optimal design for functionally graded hollow cylinders.

Directory of Open Access Journals (Sweden)

Motohiro Sato

Full Text Available The optimal distribution of the reinforcing fibers for stiffening hollow cylindrical composites is explored using the linear elasticity theory. The spatial distribution of the vascular bundles in wild bamboo, a nature-designed functionally graded material, is the basis for the design. Our results suggest that wild bamboos maximize their flexural rigidity by optimally regulating the radial gradation of their vascular bundle distribution. This fact provides us with a plant-mimetic design principle that enables the realization of high-stiffness and lightweight cylindrical composites.

A SURVEY ON OPTIMIZATION APPROACHES TO SEMANTIC SERVICE DISCOVERY TOWARDS AN INTEGRATED SOLUTION

Directory of Open Access Journals (Sweden)

Chellammal Surianarayanan

2012-07-01

Full Text Available The process of semantic service discovery using an ontology reasoner such as Pellet is time consuming. This restricts the usage of web services in real time applications having dynamic composition requirements. As performance of semantic service discovery is crucial in service composition, it should be optimized. Various optimization methods are being proposed to improve the performance of semantic discovery. In this work, we investigate the existing optimization methods and broadly classify optimization mechanisms into two categories, namely optimization by efficient reasoning and optimization by efficient matching. Optimization by efficient matching is further classified into subcategories such as optimization by clustering, optimization by inverted indexing, optimization by caching, optimization by hybrid methods, optimization by efficient data structures and optimization by efficient matching algorithms. With a detailed study of different methods, an integrated optimization infrastructure along with matching method has been proposed to improve the performance of semantic matching component. To achieve better optimization the proposed method integrates the effects of caching, clustering and indexing. Theoretical aspects of performance evaluation of the proposed method are discussed.

Development of an in-situ multi-component reinforced Al-based metal matrix composite by direct metal laser sintering technique — Optimization of process parameters

International Nuclear Information System (INIS)

Ghosh, Subrata Kumar; Bandyopadhyay, Kaushik; Saha, Partha

2014-01-01

In the present investigation, an in-situ multi-component reinforced aluminum based metal matrix composite was fabricated by the combination of self-propagating high-temperature synthesis and direct metal laser sintering process. The different mixtures of Al, TiO 2 and B 4 C powders were used to initiate and maintain the self-propagating high-temperature synthesis by laser during the sintering process. It was found from the X-ray diffraction analysis and scanning electron microscopy that the reinforcements like Al 2 O 3 , TiC, and TiB 2 were formed in the composite. The scanning electron microscopy revealed the distribution of the reinforcement phases in the composite and phase identities. The variable parameters such as powder layer thickness, laser power, scanning speed, hatching distance and composition of the powder mixture were optimized for higher density, lower porosity and higher microhardness using Taguchi method. Experimental investigation shows that the density of the specimen mainly depends upon the hatching distance, composition and layer thickness. On the other hand, hatching distance, layer thickness and laser power are the significant parameters which influence the porosity. The composition, laser power and layer thickness are the key influencing parameters for microhardness. - Highlights: • The reinforcements such as Al 2 O 3 , TiC, and TiB 2 were produced in Al-MMC through SHS. • The density is mainly influenced by the material composition and hatching distance. • Hatching distance is the major influencing parameter on porosity. • The material composition is the significant parameter to enhance the microhardness. • The SEM micrographs reveal the distribution of TiC, TiB 2 and Al 2 O 3 in the composite

Optimal Realtime Damage Identification in Composite Structures, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Intelligent Fiber Optic Systems Corporation (IFOS) proposes to develop an effective real-time, in situ damage locating and growth monitoring system of composite...

Continuous carbon nanotube reinforced composites.

Science.gov (United States)

Ci, L; Suhr, J; Pushparaj, V; Zhang, X; Ajayan, P M

2008-09-01

Carbon nanotubes are considered short fibers, and polymer composites with nanotube fillers are always analogues of random, short fiber composites. The real structural carbon fiber composites, on the other hand, always contain carbon fiber reinforcements where fibers run continuously through the composite matrix. With the recent optimization in aligned nanotube growth, samples of nanotubes in macroscopic lengths have become available, and this allows the creation of composites that are similar to the continuous fiber composites with individual nanotubes running continuously through the composite body. This allows the proper utilization of the extreme high modulus and strength predicted for nanotubes in structural composites. Here, we fabricate such continuous nanotube polymer composites with continuous nanotube reinforcements and report that under compressive loadings, the nanotube composites can generate more than an order of magnitude improvement in the longitudinal modulus (up to 3,300%) as well as damping capability (up to 2,100%). It is also observed that composites with a random distribution of nanotubes of same length and similar filler fraction provide three times less effective reinforcement in composites.

Mathematical Modelling of Optimization of Structures of Monolithic Coverings Based on Liquid Rubbers

Science.gov (United States)

Turgumbayeva, R. Kh; Abdikarimov, M. N.; Mussabekov, R.; Sartayev, D. T.

2018-05-01

The paper considers optimization of monolithic coatings compositions using a computer and MPE methods. The goal of the paper was to construct a mathematical model of the complete factorial experiment taking into account its plan and conditions. Several regression equations were received. Dependence between content components and parameters of rubber, as well as the quantity of a rubber crumb, was considered. An optimal composition for manufacturing the material of monolithic coatings compositions was recommended based on experimental data.

Development of On-line Monitoring System for Shape Memory Alloy Composite

International Nuclear Information System (INIS)

Lee, Jin Kyung; Park, Young Chul; Lee, Min Rae; Lee, Dong Hwa; Lee, Kyu Chang

2003-01-01

A hot press method was use for the optimal manufacturing condition for a shape memory alloy(SMA) composite. The bonding between the matrix and the reinforcement within the SMA composite by the hot press method was strengthened by cold rolling. In this study, the objective was to develop an on-line monitoring system for the prevention of the crack initiation and propagation by shape memory effort of SMA composite. Shape memory effect was used to prevent the SMA composite from cracking. For the system to be developed, an optimal hE parameter should be determined based on the degree of damage and crack initiation. When the SHA composite was heated by the plate heater attached at the composite, the propagating cracks appeared to be controlled by the compressive force of SMA

Optimization of sulfamethoxazole degradation by TiO{sub 2}/hydroxyapatite composite under ultraviolet irradiation using response surface methodology

Energy Technology Data Exchange (ETDEWEB)

Chun, Suk Young; Kim, Ji Tae; Chang, Soon Woong [Kyonggi University, Suwon (Korea, Republic of); An, Sang Woo [Hanyang University, Seoul (Korea, Republic of); Lee, Si Jin [Korea Environment Corporation, Incheon (Korea, Republic of)

2014-06-15

A titanium dioxide/hydroxyapatite/ultraviolet (TiO{sub 2}/HAP/UV-A) system was used to remove sulfamethoxazole (SMX) from water in a second-order response surface methodology (RSM) experiment with a three-level Box-Behnken design (BBD) for optimization. The effects of both the primary and secondary interaction effects of three photocatalytic reaction variables were examined: the concentration of SMX (X{sub 1}), dose of TiO{sub 2}/HAP composite (X{sub 2}), and UV intensity (X{sub 3}). The UV intensity and TiO{sub 2}/HAP dose significantly influence the SMX and total organic carbon (TOC) removal (p<0.001). However, the SMX and TOC removal are enhanced with increasing TiO{sub 2}/HAP dose up to certain levels, and further increases in the TiO{sub 2}/HAP dose result in adverse effects due to hydroxyl radical scavenging at higher catalyst concentrations. Complete removal of SMX was achieved upon UV-A irradiation for 180 min. Under optimal conditions, 51.2% of the TOC was removed, indicating the formation of intermediate products during SMX degradation. The optimal ratio of SMX (mg L{sup -1}) to TiO{sub 2}/HAP (g L{sup -1}) to UV (W/L) was 5.4145 mg L{sup -1} to 1.4351 g L{sup -1} to 18 W for both SMX and TOC removal. By comparison with actual applications, the experimental results were found to be in good agreement with the model's predictions, with mean results for SMX and TOC removal of 99.89% and 51.01%, respectively.

Shape optimization of high power centrifugal compressor using multi-objective optimal method

Energy Technology Data Exchange (ETDEWEB)

Kang, Hyun Soo; Lee, Jeong Min; Kim, Youn Jea [School of Mechanical Engineering, Sungkyunkwan University, Seoul (Korea, Republic of)

2015-03-15

In this study, a method for optimal design of impeller and diffuser blades in the centrifugal compressor using response surface method (RSM) and multi-objective genetic algorithm (MOGA) was evaluated. A numerical simulation was conducted using ANSYS CFX with various values of impeller and diffuser parameters, which consist of leading edge (LE) angle, trailing edge (TE) angle, and blade thickness. Each of the parameters was divided into three levels. A total of 45 design points were planned using central composite design (CCD), which is one of the design of experiment (DOE) techniques. Response surfaces that were generated on the basis of the results of DOE were used to determine the optimal shape of impeller and diffuser blade. The entire process of optimization was conducted using ANSYS Design Xplorer (DX). Through the optimization, isentropic efficiency and pressure recovery coefficient, which are the main performance parameters of the centrifugal compressor, were increased by 0.3 and 5, respectively.

Shape optimization of high power centrifugal compressor using multi-objective optimal method

International Nuclear Information System (INIS)

Kang, Hyun Soo; Lee, Jeong Min; Kim, Youn Jea

2015-01-01

In this study, a method for optimal design of impeller and diffuser blades in the centrifugal compressor using response surface method (RSM) and multi-objective genetic algorithm (MOGA) was evaluated. A numerical simulation was conducted using ANSYS CFX with various values of impeller and diffuser parameters, which consist of leading edge (LE) angle, trailing edge (TE) angle, and blade thickness. Each of the parameters was divided into three levels. A total of 45 design points were planned using central composite design (CCD), which is one of the design of experiment (DOE) techniques. Response surfaces that were generated on the basis of the results of DOE were used to determine the optimal shape of impeller and diffuser blade. The entire process of optimization was conducted using ANSYS Design Xplorer (DX). Through the optimization, isentropic efficiency and pressure recovery coefficient, which are the main performance parameters of the centrifugal compressor, were increased by 0.3 and 5, respectively

Use of Experimental Design for Peuhl Cheese Process Optimization ...

African Journals Online (AJOL)

Use of Experimental Design for Peuhl Cheese Process Optimization. ... Journal of Applied Sciences and Environmental Management ... This work consisting in use of a central composite design enables the determination of optimal process conditions concerning: leaf extract volume added (7 mL), heating temperature ...

Medium optimization for protopectinase production by batch culture of

African Journals Online (AJOL)

Medium optimization for protopectinase production by batch culture of. C Fan, Z Liu, L Yao. Abstract. Optimization of medium compositions for protopectinase production by Aspergillus terreus in submerged culture was carried out. The medium components having significant effect on protopectinase production were reported ...

Friction Joint Between Basalt-Reinforced Composite and Aluminum

DEFF Research Database (Denmark)

Costache, Andrei; Glejbøl, Kristian; Sivebæk, Ion Marius

2015-01-01

The purpose of this study was to anchor basalt-reinforced polymers in an aluminum grip using dry friction. Dry friction clamping is considered the optimal solution for post-mounting of load-bearing terminations on composite structures. A new test method is presented for characterizing the frictio......The purpose of this study was to anchor basalt-reinforced polymers in an aluminum grip using dry friction. Dry friction clamping is considered the optimal solution for post-mounting of load-bearing terminations on composite structures. A new test method is presented for characterizing...

Development of an in-situ multi-component reinforced Al-based metal matrix composite by direct metal laser sintering technique — Optimization of process parameters

Energy Technology Data Exchange (ETDEWEB)

Ghosh, Subrata Kumar, E-mail: subratagh82@gmail.com [Department of Mechanical Engineering, National Institute of Technology Agartala, Tripura 799055 (India); Bandyopadhyay, Kaushik; Saha, Partha [Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)

2014-07-01

In the present investigation, an in-situ multi-component reinforced aluminum based metal matrix composite was fabricated by the combination of self-propagating high-temperature synthesis and direct metal laser sintering process. The different mixtures of Al, TiO{sub 2} and B{sub 4}C powders were used to initiate and maintain the self-propagating high-temperature synthesis by laser during the sintering process. It was found from the X-ray diffraction analysis and scanning electron microscopy that the reinforcements like Al{sub 2}O{sub 3}, TiC, and TiB{sub 2} were formed in the composite. The scanning electron microscopy revealed the distribution of the reinforcement phases in the composite and phase identities. The variable parameters such as powder layer thickness, laser power, scanning speed, hatching distance and composition of the powder mixture were optimized for higher density, lower porosity and higher microhardness using Taguchi method. Experimental investigation shows that the density of the specimen mainly depends upon the hatching distance, composition and layer thickness. On the other hand, hatching distance, layer thickness and laser power are the significant parameters which influence the porosity. The composition, laser power and layer thickness are the key influencing parameters for microhardness. - Highlights: • The reinforcements such as Al{sub 2}O{sub 3}, TiC, and TiB{sub 2} were produced in Al-MMC through SHS. • The density is mainly influenced by the material composition and hatching distance. • Hatching distance is the major influencing parameter on porosity. • The material composition is the significant parameter to enhance the microhardness. • The SEM micrographs reveal the distribution of TiC, TiB{sub 2} and Al{sub 2}O{sub 3} in the composite.

Reliable execution based on CPN and skyline optimization for Web service composition.

Science.gov (United States)

Chen, Liping; Ha, Weitao; Zhang, Guojun

2013-01-01

With development of SOA, the complex problem can be solved by combining available individual services and ordering them to best suit user's requirements. Web services composition is widely used in business environment. With the features of inherent autonomy and heterogeneity for component web services, it is difficult to predict the behavior of the overall composite service. Therefore, transactional properties and nonfunctional quality of service (QoS) properties are crucial for selecting the web services to take part in the composition. Transactional properties ensure reliability of composite Web service, and QoS properties can identify the best candidate web services from a set of functionally equivalent services. In this paper we define a Colored Petri Net (CPN) model which involves transactional properties of web services in the composition process. To ensure reliable and correct execution, unfolding processes of the CPN are followed. The execution of transactional composition Web service (TCWS) is formalized by CPN properties. To identify the best services of QoS properties from candidate service sets formed in the TCSW-CPN, we use skyline computation to retrieve dominant Web service. It can overcome that the reduction of individual scores to an overall similarity leads to significant information loss. We evaluate our approach experimentally using both real and synthetically generated datasets.

ACT Payload Shroud Structural Concept Analysis and Optimization

Science.gov (United States)

Zalewski, Bart B.; Bednarcyk, Brett A.

2010-01-01

Aerospace structural applications demand a weight efficient design to perform in a cost effective manner. This is particularly true for launch vehicle structures, where weight is the dominant design driver. The design process typically requires many iterations to ensure that a satisfactory minimum weight has been obtained. Although metallic structures can be weight efficient, composite structures can provide additional weight savings due to their lower density and additional design flexibility. This work presents structural analysis and weight optimization of a composite payload shroud for NASA s Ares V heavy lift vehicle. Two concepts, which were previously determined to be efficient for such a structure are evaluated: a hat stiffened/corrugated panel and a fiber reinforced foam sandwich panel. A composite structural optimization code, HyperSizer, is used to optimize the panel geometry, composite material ply orientations, and sandwich core material. HyperSizer enables an efficient evaluation of thousands of potential designs versus multiple strength and stability-based failure criteria across multiple load cases. HyperSizer sizing process uses a global finite element model to obtain element forces, which are statistically processed to arrive at panel-level design-to loads. These loads are then used to analyze each candidate panel design. A near optimum design is selected as the one with the lowest weight that also provides all positive margins of safety. The stiffness of each newly sized panel or beam component is taken into account in the subsequent finite element analysis. Iteration of analysis/optimization is performed to ensure a converged design. Sizing results for the hat stiffened panel concept and the fiber reinforced foam sandwich concept are presented.

Multivariate optimization of process parameters in the synthesis of calcined Ca‒Al (NO3) LDH for defluoridation using 3(3) factorial, central composite and Box-Behnken design.

Science.gov (United States)

Ghosal, Partha S; Gupta, Ashok K; Sulaiman, Ayoob

2016-01-01

Response surface methodology was applied for the first time in the optimization of the preparation of layered double hydroxide (LDH) for defluoridation. The influence of three vital process parameters (viz. pH, molar ratio and calcination temperature) in the synthesis of the adsorbent 'Calcined Ca‒Al (NO3) LDH' was thoroughly examined to maximize its fluoride scavenging potential. The process parameters were optimized using the 3(3) factorial, face centered central composite and Box-Behnken designs and a comparative assessment of the methods was conducted. The maximum fluoride removal efficiency was achieved at a calcination temperature of approximately 500ºC; however, the efficiency decreased with increasing pH and molar ratio. The outcome of the comparative assessment clearly delineates the case specific nature of the models. A better predictability over the entire experimental domain was obtained with the 3(3) factorial method, whereas the Box-Behnken design was found to be the most efficient model with lesser number of experimental runs. The desirability function technique was performed for optimizing the response, wherein face centered central composite design exhibited a maximum desirability. The calcined Ca‒Al (NO3) LDH, synthesized under the optimum conditions, demonstrated the removal efficiencies of 95% and 99% for the doses of 3 g L(-1) and 5 g L(-1), respectively.

Multi-response optimization of machining characteristics in ultrasonic machining of WC-Co composite through Taguchi method and grey-fuzzy logic

Directory of Open Access Journals (Sweden)

Ravi Pratap Singh

2018-01-01

Full Text Available This article addresses the application of grey based fuzzy logic coupled with Taguchi’s approach for optimization of multi performance characteristics in ultrasonic machining of WC-Co composite material. The Taguchi’s L-36 array has been employed to conduct the experimentation and also to observe the influence of different process variables (power rating, cobalt content, tool geometry, thickness of work piece, tool material, abrasive grit size on machining characteristics. Grey relational fuzzy grade has been computed by converting the multiple responses, i.e., material removal rate and tool wear rate obtained from Taguchi’s approach into a single performance characteristic using grey based fuzzy logic. In addition, analysis of variance (ANOVA has also been attempted in a view to identify the significant parameters. Results revealed grit size and power rating as leading parameters for optimization of multi performance characteristics. From the microstructure analysis, the mode of material deformation has been observed and the critical parameters (i.e., work material properties, grit size, and power rating for the deformation mode have been established.

Optimization of medium for the production of subtilisin from Bacillus ...

African Journals Online (AJOL)

The effect of yeast extract, casein, peptone and sodium chloride on subtilisin production was studied and were optimized using Box Behnken Design. The optimal growth conditions for B. subtilis MTCC 441 were found to 37oC, and pH 7.5. The optimal media composition for subtilisin production was found to be yeast extract ...

Diversity shrinkage: Cross-validating pareto-optimal weights to enhance diversity via hiring practices.

Science.gov (United States)

Song, Q Chelsea; Wee, Serena; Newman, Daniel A

2017-12-01

To reduce adverse impact potential and improve diversity outcomes from personnel selection, one promising technique is De Corte, Lievens, and Sackett's (2007) Pareto-optimal weighting strategy. De Corte et al.'s strategy has been demonstrated on (a) a composite of cognitive and noncognitive (e.g., personality) tests (De Corte, Lievens, & Sackett, 2008) and (b) a composite of specific cognitive ability subtests (Wee, Newman, & Joseph, 2014). Both studies illustrated how Pareto-weighting (in contrast to unit weighting) could lead to substantial improvement in diversity outcomes (i.e., diversity improvement), sometimes more than doubling the number of job offers for minority applicants. The current work addresses a key limitation of the technique-the possibility of shrinkage, especially diversity shrinkage, in the Pareto-optimal solutions. Using Monte Carlo simulations, sample size and predictor combinations were varied and cross-validated Pareto-optimal solutions were obtained. Although diversity shrinkage was sizable for a composite of cognitive and noncognitive predictors when sample size was at or below 500, diversity shrinkage was typically negligible for a composite of specific cognitive subtest predictors when sample size was at least 100. Diversity shrinkage was larger when the Pareto-optimal solution suggested substantial diversity improvement. When sample size was at least 100, cross-validated Pareto-optimal weights typically outperformed unit weights-suggesting that diversity improvement is often possible, despite diversity shrinkage. Implications for Pareto-optimal weighting, adverse impact, sample size of validation studies, and optimizing the diversity-job performance tradeoff are discussed. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

INVESTIGATION OF CEMENT CONCRETE CONGLOMERATE SOLIDIFICATION PROCESS BY IMPEDANCE SPECTROSCOPY METHOD

Directory of Open Access Journals (Sweden)

S. N. Bandarenka

2015-01-01

are connected with usage of technogenic wastes (e.g. granite chippings as a fine aggregate and optimization of mineral and granulometric mix composition for road pavement. Development of an approach for investigation of properties on cement concrete materials on the basis of an impedance spectrum analysis will permit  quantitatively to characterize processes which are occurring in them including such processes as concrete solidification and corrosion.

Property-based design: optimization and characterization of polyvinyl alcohol (PVA) hydrogel and PVA-matrix composite for artificial cornea.

Science.gov (United States)

Jiang, Hong; Zuo, Yi; Zhang, Li; Li, Jidong; Zhang, Aiming; Li, Yubao; Yang, Xiaochao

2014-03-01

Each approach for artificial cornea design is toward the same goal: to develop a material that best mimics the important properties of natural cornea. Accordingly, the selection and optimization of corneal substitute should be based on their physicochemical properties. In this study, three types of polyvinyl alcohol (PVA) hydrogels with different polymerization degree (PVA1799, PVA2499 and PVA2699) were prepared by freeze-thawing techniques. After characterization in terms of transparency, water content, water contact angle, mechanical property, root-mean-square roughness and protein adsorption behavior, the optimized PVA2499 hydrogel with similar properties of natural cornea was selected as a matrix material for artificial cornea. Based on this, a biomimetic artificial cornea was fabricated with core-and-skirt structure: a transparent PVA hydrogel core, surrounding by a ringed PVA-matrix composite skirt that composed of graphite, Fe-doped nano hydroxyapatite (n-Fe-HA) and PVA hydrogel. Different ratio of graphite/n-Fe-HA can tune the skirt color from dark brown to light brown, which well simulates the iris color of Oriental eyes. Moreover, morphologic and mechanical examination showed that an integrated core-and-skirt artificial cornea was formed from an interpenetrating polymer network, no phase separation appeared on the interface between the core and the skirt.

Studies on the optimization of deformation processed metal metal matrix composites

Energy Technology Data Exchange (ETDEWEB)

Ellis, Tim W. [Iowa State Univ., Ames, IA (United States)

1994-01-04

A methodology for the production of deformation processed metal metal matrix composites from hyper-eutectic copper-chromium alloys was developed. This methodology was derived from a basic study of the precipitation phenomena in these alloys encompassing evaluation of microstructural, electrical, and mechanical properties. The methodology developed produces material with a superior combination of electrical and mechanical properties compared to those presently available in commercial alloys. New and novel alloying procedures were investigated to extend the range of production methods available for these material. These studies focused on the use of High Pressure Gas Atomization and the development of new containment technologies for the liquid alloy. This allowed the production of alloys with a much more refined starting microstructure and lower contamination than available by other methods. The knowledge gained in the previous studies was used to develop two completely new families of deformation processed metal metal matrix composites. These composites are based on immissible alloys with yttrium and magnesium matrices and refractory metal reinforcement. This work extends the physical property range available in deformation processed metal metal matrix composites. Additionally, it also represents new ways to apply these metals in engineering applications.

Research on optimizing components of microfine high-performance composite cementitious materials

International Nuclear Information System (INIS)

Hu Shuguang; Guan Xuemao; Ding Qingjun

2002-01-01

The relationship between material components and mechanical properties was studied in terms of composite material principles and orthogonal experimental design. Moreover, the microstructure of microfine high-performance composite cementitious material (MHPCC) paste was investigated by means of scanning electron microscopy (SEM) methods. The results showed that the composite material consisting of blast furnace slag (BFS), gypsum (G 2 ) and expansive agent (EA) could obviously improve the strength of the cementitious material containing 40% fly ash (FA). Although microfine cement (MC) was merely 45% percent of the MHPCC, the compressive strength of MHPCC paste was higher than that of neat MC paste. BFS played an important role in MHPCC. The optimum-added quantity of BFS was 15%. The needle-shaped ettringite obtained from the EA reacting with Ca(OH) 2 forms a three-dimensional network structure, which not only improved the early strength of MHPCC paste but also increased its late strength. The reason was that the network structure, which was similar to a fiber-reinforced composite, was formed in the late period of hydration with the progress of hydration and the deposition of hydration products into the network structure

Steady-state optimization of ore-dressing plants

International Nuclear Information System (INIS)

Niemi, A.J.

1989-01-01

The ore-dressing plant consists of the steps of grinding and flotation. Its optimization is based on steady state simulation of the mass balances with a plant model. The model data are obtained by tracer tests and analysis. An evaluation of performance of the plant has to observe the recovery of the valuable mineral, the throughput of the system and the grade of the concentrate which are outputs of the flotation plant. Simulation with the flotation plant model yields that combination of values of controllable inputs to flotation which corresponds to an optimal operation of the conditioning an flotation system, for a specified feed and its fractional composition. Simulations for other feeds and compositions advise how they should be chosen, for a better overall performance. (author)

Analysis of main parameters affecting substrate/mortar contact area through tridimensional laser scanner.

Science.gov (United States)

Stolz, Carina M; Masuero, Angela B

2015-10-01

This study assesses the influence of the granulometric composition of sand, application energy and the superficial tension of substrates on the contact area of rendering mortars. Three substrates with distinct wetting behaviors were selected and mortars were prepared with different sand compositions. Characterization tests were performed on fresh and hardened mortars, as well as the rheological characterization. Mortars were applied to substrates with two different energies. The interfacial area was then digitized with 3D scanner. Results show that variables are all of influence on the interfacial contact in the development area. Furthermore, 3D laser scanning proved to be a good method to contact area measurement. Copyright © 2015 Elsevier Inc. All rights reserved.

SU-E-T-436: Fluence-Based Trajectory Optimization for Non-Coplanar VMAT

Energy Technology Data Exchange (ETDEWEB)

Smyth, G; Bamber, JC; Bedford, JL [Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London (United Kingdom); Evans, PM [Centre for Vision, Speech and Signal Processing, University of Surrey, Guildford (United Kingdom); Saran, FH; Mandeville, HC [The Royal Marsden NHS Foundation Trust, Sutton (United Kingdom)

2015-06-15

Purpose: To investigate a fluence-based trajectory optimization technique for non-coplanar VMAT for brain cancer. Methods: Single-arc non-coplanar VMAT trajectories were determined using a heuristic technique for five patients. Organ at risk (OAR) volume intersected during raytracing was minimized for two cases: absolute volume and the sum of relative volumes weighted by OAR importance. These trajectories and coplanar VMAT formed starting points for the fluence-based optimization method. Iterative least squares optimization was performed on control points 24° apart in gantry rotation. Optimization minimized the root-mean-square (RMS) deviation of PTV dose from the prescription (relative importance 100), maximum dose to the brainstem (10), optic chiasm (5), globes (5) and optic nerves (5), plus mean dose to the lenses (5), hippocampi (3), temporal lobes (2), cochleae (1) and brain excluding other regions of interest (1). Control point couch rotations were varied in steps of up to 10° and accepted if the cost function improved. Final treatment plans were optimized with the same objectives in an in-house planning system and evaluated using a composite metric - the sum of optimization metrics weighted by importance. Results: The composite metric decreased with fluence-based optimization in 14 of the 15 plans. In the remaining case its overall value, and the PTV and OAR components, were unchanged but the balance of OAR sparing differed. PTV RMS deviation was improved in 13 cases and unchanged in two. The OAR component was reduced in 13 plans. In one case the OAR component increased but the composite metric decreased - a 4 Gy increase in OAR metrics was balanced by a reduction in PTV RMS deviation from 2.8% to 2.6%. Conclusion: Fluence-based trajectory optimization improved plan quality as defined by the composite metric. While dose differences were case specific, fluence-based optimization improved both PTV and OAR dosimetry in 80% of cases.

Compositional effects on the formation of a calcium phosphate layer and the response of osteoblast-like cells on polymer-bioactive glass composites.

Science.gov (United States)

Lu, Helen H; Tang, Amy; Oh, Seong Cheol; Spalazzi, Jeffrey P; Dionisio, Kathie

2005-11-01

Biodegradable polymer-ceramic composites are attractive systems for bone tissue engineering applications. These composites have the combined advantages of the component phases, as well as the inherent ease in optimization where desired material properties can be tailored in a well-controlled manner. This study focuses on the optimization of a polylactide-co-glycolide (PLAGA) and 45S5 bioactive glass (BG) composite for bone tissue engineering. The first objective is to examine the effects of composition or overall BG content on the formation of a Ca-P layer on the PLAGA-BG composite. It is expected that with increasing BG content (0%, 10%, 25%, 50% by weight), the required incubation time in a simulated body fluid (SBF) for the composite to form a detectable surface Ca-P layer will decrease. Both the kinetics and the chemistry will be determined using SEM+EDAX, FTIR, and mu-CT methods. Solution phosphorous and calcium concentrations will also be measured. The second objective of the study is to determine the effects of BG content on the maturation of osteoblast-like cells on the PLAGA-BG composite. It is hypothesized that mineralization will increase with increasing BG content, and the composite will support the proliferation and differentiation of osteoblasts. Specifically, cell proliferation, alkaline phosphatase activity and mineralization will be monitored as a function of BG content (0%, 10%, 50% by weight) and culturing time. It was found that the kinetics of Ca-P layer formation and the resulting Ca-P chemistry were dependent on BG content. The response of human osteoblast-like cells to the PLAGA-BG composite was also a function of BG content. The 10% and 25% BG composite supported greater osteoblast growth and differentiation compared to the 50% BG group. The results of this study suggest that there is a threshold BG content which is optimal for osteoblast growth, and the interactions between PLAGA and BG may modulate the kinetics of Ca-P formation and the

Identification of Optimal Preventive Maintenance Decisions for Composite Components

NARCIS (Netherlands)

Laks, P.; Verhagen, W.J.C.; Gherman, B.; Porumbel, I.

2018-01-01

This research proposes a decision support tool which identifies cost-optimal maintenance decisions for a given planning period. Simultaneously, the reliability state of the component is kept at or below a given reliability threshold: a failure limit policy applies. The tool is developed to support

Present State of the Art of Composite Fabric Forming: Geometrical and Mechanical Approaches

Science.gov (United States)

Cherouat, Abel; Borouchaki, Houman

2009-01-01

Continuous fibre reinforced composites are now firmly established engineering materials for the manufacture of components in the automotive and aerospace industries. In this respect, composite fabrics provide flexibility in the design manufacture. The ability to define the ply shapes and material orientation has allowed engineers to optimize the composite properties of the parts. The formulation of new numerical models for the simulation of the composite forming processes must allow for reduction in the delay in manufacturing and an optimization of costs in an integrated design approach. We propose two approaches to simulate the deformation of woven fabrics: geometrical and mechanical approaches.

Ultrasonic Characterization of Aerospace Composites

Science.gov (United States)

Leckey, Cara; Johnston, Patrick; Haldren, Harold; Perey, Daniel

2015-01-01

Composite materials have seen an increased use in aerospace in recent years and it is expected that this trend will continue due to the benefits of reduced weight, increased strength, and other factors. Ongoing work at NASA involves the investigation of the large-scale use of composites for spacecraft structures (SLS components, Orion Composite Crew Module, etc). NASA is also involved in work to enable the use of composites in advanced aircraft structures through the Advanced Composites Project (ACP). In both areas (space and aeronautics) there is a need for new nondestructive evaluation and materials characterization techniques that are appropriate for characterizing composite materials. This paper will present an overview of NASA's needs for characterizing aerospace composites, including a description of planned and ongoing work under ACP for the detection of composite defects such as fiber waviness, reduced bond strength, delamination damage, and microcracking. The research approaches include investigation of angle array, guided wave, and phase sensitive ultrasonic methods. The use of ultrasonic simulation tools for optimizing and developing methods will also be discussed.

Research and Development Progress of National Key Laboratory of Advanced Composites on Advanced Aeronautical Resin Matrix Composites

Directory of Open Access Journals (Sweden)

LI Bintai

2016-06-01

Full Text Available Applications and research progress in advanced aeronautical resin matrix composites by National Key Laboratory of Advanced Composites (LAC were summarized. A novel interlaminar toughening technology employing ultra-thin TP non-woven fabric was developed in LAC, which significantly improved the compression after impact (CAI performances of composite laminates.Newly designed multilayer sandwich stealth composite structures exhibited a good broadband radar absorbing properties at 1-18 GHz.There were remarkable developments in high toughness and high temperature resin matrix composites, covering major composite processing technologies such as prepreg-autoclave procedure, liquid composite molding and automation manufacture, etc. Finally, numerical simulation and optimization methods were deliberately utilized in the study of composites curing behavior, resin flow and curing deformation. A composite material database was also established.In conclusion, LAC has been a great support for the development of aeronautical equipment, playing such roles as innovation leading, system dominating, foundation supporting and application ensuring of aerocomposites.

Optimization of friction and wear behaviour of Al7075-Al2O3-B4C metal matrix composites using Taguchi method

Science.gov (United States)

Dhanalakshmi, S.; Mohanasundararaju, N.; Venkatakrishnan, P. G.; Karthik, V.

2018-02-01

The present study deals with investigations relating to dry sliding wear behaviour of the Al 7075 alloy, reinforced with Al2O3 and B4C. The hybrid composites are produced through Liquid Metallurgy route - Stir casting method. The amount of Al2O3 particles is varied as 3, 6, 9, 12 and 15 wt% and the amount of B4C is kept constant as 3wt%. Experiments were conducted based on the plan of experiments generated through Taguchi’s technique. A L27 Orthogonal array was selected for analysis of the data. The investigation is to find the effect of applied load, sliding speed and sliding distance on wear rate and Coefficient of Friction (COF) of the hybrid Al7075- Al2O3-B4C composite and to determine the optimal parameters for obtaining minimum wear rate. The samples were examined using scanning electronic microscopy after wear testing and analyzed.

Optimization and characterization of liposome formulation by mixture design.

Science.gov (United States)

Maherani, Behnoush; Arab-tehrany, Elmira; Kheirolomoom, Azadeh; Reshetov, Vadzim; Stebe, Marie José; Linder, Michel

2012-02-07

This study presents the application of the mixture design technique to develop an optimal liposome formulation by using the different lipids in type and percentage (DOPC, POPC and DPPC) in liposome composition. Ten lipid mixtures were generated by the simplex-centroid design technique and liposomes were prepared by the extrusion method. Liposomes were characterized with respect to size, phase transition temperature, ζ-potential, lamellarity, fluidity and efficiency in loading calcein. The results were then applied to estimate the coefficients of mixture design model and to find the optimal lipid composition with improved entrapment efficiency, size, transition temperature, fluidity and ζ-potential of liposomes. The response optimization of experiments was the liposome formulation with DOPC: 46%, POPC: 12% and DPPC: 42%. The optimal liposome formulation had an average diameter of 127.5 nm, a phase-transition temperature of 11.43 °C, a ζ-potential of -7.24 mV, fluidity (1/P)(TMA-DPH)((¬)) value of 2.87 and an encapsulation efficiency of 20.24%. The experimental results of characterization of optimal liposome formulation were in good agreement with those predicted by the mixture design technique.

Optimization and Static Stress Analysis of Hybrid Fiber Reinforced Composite Leaf Spring

Directory of Open Access Journals (Sweden)

Luay Muhammed Ali Ismaeel

2015-01-01

Full Text Available A monofiber reinforced composite leaf spring is proposed as an alternative to the typical steel one as it is characterized by high strength-to-weight ratio. Different reinforcing schemes are suggested to fabricate the leaf spring. The composite and the typical steel leaf springs are subjected to the same working conditions. A weight saving of about more than 60% can be achieved while maintaining the strength for the structures under consideration. The objective of the present study was to replace material for leaf spring. This study suggests various materials of hybrid fiber reinforced plastics (HFRP. Also the effects of shear moduli of the fibers, matrices, and the composites on the composites performance and responses are discussed. The results and behaviors of each are compared with each other and verified by comparison with analytical solution; a good convergence is found between them. The elastic properties of the hybrid composites are calculated using rules of mixtures and Halpin-Tsi equation through the software of MATLAB v-7. The problem is also analyzed by the technique of finite element analysis (FEA through the software of ANSYS v-14. An element modeling was done for every leaf with eight-node 3D brick element (SOLID185 3D 8-Node Structural Solid.

Optimization of photosynthesis, growth, and biochemical composition of the microalga Rhodomonas salina

DEFF Research Database (Denmark)

Thuy, Minh Vu Thi; Douëtte, Claire; Rayner, Thomas Allan

2016-01-01

The cryptophyte Rhodomonas salina is widely used as feed for copepod cultures. However, culturing conditions to obtain high-quality algae have not yet been efficiently optimized. Therefore, we aimed to develop a cultivation protocol for R. salina to optimize its nutritional value and provide tech...

Composites as structural materials in fusion reactors

International Nuclear Information System (INIS)

Megusar, J.

1989-01-01

In fusion reactors, materials are used under extreme conditions of temperature, stress, irradiation, and chemical environment. The absence of adequate materials will seriously impede the development of fusion reactors and might ultimately be one of the major difficulties. Some of the current materials problems can be solved by proper design features. For others, the solution will have to rely on materials development. A parallel and balanced effort between the research in plasma physics and fusion-related technology and in materials research is, therefore, the best strategy to ultimately achieve economic, safe, and environmentally acceptable fusion. The essential steps in developing composites for structural components of fusion reactors include optimization of mechanical properties followed by testing under fusion-reactor-relevant conditions. In optimizing the mechanical behavior of composite materials, a wealth of experience can be drawn from the research on ceramic matrix and metal matrix composite materials sponsored by the Department of Defense. The particular aspects of this research relevant to fusion materials development are methodology of the composite materials design and studies of new processing routes to develop composite materials with specific properties. Most notable examples are the synthesis of fibers, coatings, and ceramic materials in their final shapes form polymeric precursors and the infiltration of fibrous preforms by molten metals

Mathematical model of the rating and weighted wholesale value of enriched anthracite. [Effects of winning, preparation and transport on lump size and threefore value

Energy Technology Data Exchange (ETDEWEB)

Malets, A L; Tikhomirov, A G

1977-01-01

A method is developed for the numerical determination of the fragmentation of anthracite at the working face and during its movement through an enrichment plant on the wholesale value of the cost. The mathematical model takes into consideration the basic factors affecting the dust content (rating criteria) in the grade coal: type of mining machine, amount of coal remaining after passage of the mining machine, coal strength, length and means of transport of the coal to the surface, granulometric composition of the coal, and the fragmentation process. (In Russian)

Use of Tesla NZK 203 neutron probe in studying water as geochemical factor in weathering zone

International Nuclear Information System (INIS)

Hally, J.

1980-01-01

The Tesla NZK 203 neutron moisture gage was used for determining soil moisture in depths of 1 and 2 meters in the Luha-Kacerov profile in the Zelivka water reservoir basin. The borehole spacing was 100 m. Measurements were made once a month between May and October 1978. The results were compared with the granulometric composition and the values of the specific surface areas of earths in the area. The Tesla NZK 203 moisture gage was fully proven for speedy measurement of volume moisture at constant measuring points. (Ha)

Precipitation of Calcium Carbonate in the Presence of Urea at 293 K and 343 K

OpenAIRE

Białowicz Katarzyna; Kiełkowska Urszula

2014-01-01

The results of the precipitation of calcium carbonate from a waste post-distillation liquid (DS) and a sodium bicarbonate saturated solution – both from the Solvay method – in the presence of urea are presented. The investigation was carried out at 293 K and 343 K. Reagent dosage times of 1, 5, 10, 20 and 30 min, and urea concentrations of 5, 6 and 10 mol/dm3 were applied. The granulometric composition, the values of bulk and packing densities and the absorptiveness sorption of water and para...

Multi-response optimization of process parameters using Taguchi method and grey relational analysis during turning AA 7075/SiC composite in dry and spray cooling environments

Directory of Open Access Journals (Sweden)

P. C. Mishra

2015-09-01

Full Text Available Turning experiments were carried out on AA 7075/SiC composite workpiece in dry and spray cooling environments based on L16 Taguchi design of experiments. Multiple performance optimization of process parameters was performed using grey relational analysis. The performance characteristics considered were average surface roughness, cutting tool temperature and material removal rate. Uncoated carbide inserts were used for machining the workpiece in a high speed precision lathe. A grey relational grade obtained from grey relational analysis was used to optimize the process parameters. Optimal combination of process parameters was then determined by the Taguchi method using the grey relational grade as the performance index. Experimental results indicated that the turning in spray cooling environment was beneficial compared to that in dry environment for the quality response characteristics under consideration. Analysis of variance showed that feed was the most significant parameter for the multiple performance characteristics during turning in both the environments.

Design Optimization of Hybrid FRP/RC Bridge

Science.gov (United States)

Papapetrou, Vasileios S.; Tamijani, Ali Y.; Brown, Jeff; Kim, Daewon

2018-04-01

The hybrid bridge consists of a Reinforced Concrete (RC) slab supported by U-shaped Fiber Reinforced Polymer (FRP) girders. Previous studies on similar hybrid bridges constructed in the United States and Europe seem to substantiate these hybrid designs for lightweight, high strength, and durable highway bridge construction. In the current study, computational and optimization analyses were carried out to investigate six composite material systems consisting of E-glass and carbon fibers. Optimization constraints are determined by stress, deflection and manufacturing requirements. Finite Element Analysis (FEA) and optimization software were utilized, and a framework was developed to run the complete analyses in an automated fashion. Prior to that, FEA validation of previous studies on similar U-shaped FRP girders that were constructed in Poland and Texas is presented. A finer optimization analysis is performed for the case of the Texas hybrid bridge. The optimization outcome of the hybrid FRP/RC bridge shows the appropriate composite material selection and cross-section geometry that satisfies all the applicable Limit States (LS) and, at the same time, results in the lightest design. Critical limit states show that shear stress criteria determine the optimum design for bridge spans less than 15.24 m and deflection criteria controls for longer spans. Increased side wall thickness can reduce maximum observed shear stresses, but leads to a high weight penalty. A taller cross-section and a thicker girder base can efficiently lower the observed deflections and normal stresses. Finally, substantial weight savings can be achieved by the optimization framework if base and side-wall thickness are treated as independent variables.

Optimization methods in structural design

CERN Document Server

Rothwell, Alan

2017-01-01

This book offers an introduction to numerical optimization methods in structural design. Employing a readily accessible and compact format, the book presents an overview of optimization methods, and equips readers to properly set up optimization problems and interpret the results. A ‘how-to-do-it’ approach is followed throughout, with less emphasis at this stage on mathematical derivations. The book features spreadsheet programs provided in Microsoft Excel, which allow readers to experience optimization ‘hands-on.’ Examples covered include truss structures, columns, beams, reinforced shell structures, stiffened panels and composite laminates. For the last three, a review of relevant analysis methods is included. Exercises, with solutions where appropriate, are also included with each chapter. The book offers a valuable resource for engineering students at the upper undergraduate and postgraduate level, as well as others in the industry and elsewhere who are new to these highly practical techniques.Whi...

Optimization for ultrasound-assisted extraction of polysaccharides with chemical composition and antioxidant activity from the Artemisia sphaerocephala Krasch seeds.

Science.gov (United States)

Zheng, Quan; Ren, Daoyuan; Yang, Nana; Yang, Xingbin

2016-10-01

Artemisia sphaerocephala Krasch seeds polysaccharides have been reported to have a variety of important biological activities. However, effective extraction of Artemisia sphaerocephala Krasch seeds polysaccharides is still an unsolved issue. In this study, the orthogonal rotatable central composite design was employed to optimize ultrasound-assisted extraction conditions of Artemisia sphaerocephala Krasch seeds polysaccharides. Based on a single-factor analysis method, ultrasonic power, extraction time, solid-liquid ratio and extraction temperature were shown to significantly affect the yield of polysaccharides extracted from the A. sphaerocephala Krasch seeds. The optimal conditions for extraction of Artemisia sphaerocephala Krasch seeds polysaccharides were determined as following: ultrasonic power 243W, extraction time 125min, solid-liquid ratio 64:1 and extraction temperature 64°C, where the experimental yield was 14.78%, which was well matched with the predicted value of 14.81%. Furthermore, ASKP was identified as a typical heteropolysaccharide with d-galacturonic acid (38.8%) d-galactose (20.2%) and d-xylose (15.5%) being the main constitutive monosaccharides. Moreover, Artemisia sphaerocephala Krasch seeds polysaccharides exhibited high total reducing power and considerable scavenging activities on DPPH, hydroxyl and superoxide radicals, in a concentration-dependent manner in vitro. Copyright © 2016 Elsevier B.V. All rights reserved.

Theory and Algorithms for Global/Local Design Optimization

National Research Council Canada - National Science Library

Watson, Layne T; Guerdal, Zafer; Haftka, Raphael T

2005-01-01

The motivating application for this research is the global/local optimal design of composite aircraft structures such as wings and fuselages, but the theory and algorithms are more widely applicable...

Use of Simplex Method in Determination of Optimal Rational ...

African Journals Online (AJOL)

The optimal rational composition was found to be: Nsu Clay = 47.8%, quartz = 33.7% and CaCO3 = 18.5%. The other clay from Ukpor was found unsuitable at the firing temperature (l000°C) used. It showed bending strength lower than the standard requirement for all compositions studied. To improve the strength an ...

Ionic Liquid Epoxy Composite Cryotanks, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The objective of this work is to determine the optimal process for manufacturing lightweight linerless cryogenic storage tanks using ionic liquid epoxy composite...

Creation of smart composites using an embroidery machine

Science.gov (United States)

Torii, Nobuhiro; Oka, Kosuke; Ikeda, Tadashige

2016-04-01

A smart composite with functional fibers and reinforcement fibers optimally placed with an embroidery machine was created. Fiber orientation affects mechanical properties of composite laminates significantly. Accordingly, if the fibers can be placed along a desired curved path, fiber reinforced plastic (FRP) structures can be designed more lightly and more sophisticatedly. To this end a tailored fiber placement method using the embroidery machine have been studied. To add functions to the FRP structures, shape memory alloy (SMA) wires were placed as functional fibers. First, for a certain purpose the paths of the reinforcement fibers and the SMA wires were simultaneously optimized in analysis. Next, the reinforcement fibers and tubes with the SMA wires were placed on fabrics by using the embroidery machine and this fabric was impregnated with resin by using the vacuum assisted resin transfer molding method. This smart composite was activated by applying voltage to the SMA wires. Fundamental properties of the smart composite were examined and the feasibility of the proposed creation method was shown.

Optimization of material composition of nonhomogeneous plate for thermal stress relaxation making use of neural network. Analysis taking into account the relative heat transfer at boundary surfaces when subjected to unsteady heat supply

International Nuclear Information System (INIS)

Ootao, Yoshihiro; Kawamura, Ryuusuke; Tanigawa, Yoshinobu; Imamura, Ryuutarou

1998-01-01

In this study, a neural network is applied to optimization problems of material compositions for a nonhomogeneous plate with arbitrarily distributed and continuously varied material properties such as Functionally Graded Material. Unsteady temperature distribution for such nonhomogeneous plate is evaluated by taking into account the bounds of the number of the layers. Furthermore, the thermal stress components for an infinitely long nonhomogeneous plate are formulated under the mechanical condition of being traction free. As a numerical example, the plate composed of zirconium oxide and titanium alloy is considered. And, as the optimization problem of minimizing the thermal stress distribution, the numerical calculations are carried out making use of neural network, and the optimum material composition is determined taking into account the effect of temperature-dependency of material properties. Furthermore, the results obtained by neural network and ordinary nonlinear programming method are compared. (author)

Plant fibre composites - porosity and volumetric interaction

DEFF Research Database (Denmark)

Madsen, Bo; Thygesen, Anders; Lilholt, Hans

2007-01-01

the combination of a high fibre volume fraction, a low porosity and a high composite density is optimal. Experimental data from the literature on volumetric composition and density of four types of plant fibre composites are used to validate the model. It is demonstrated that the model provides a concept......Plant fibre composites contain typically a relative large amount of porosity, which considerably influences properties and performance of the composites. The large porosity must be integrated in the conversion of weight fractions into volume fractions of the fibre and matrix parts. A model...... is presented to predict the porosity as a function of the fibre weight fractions, and to calculate the related fibre and matrix volume fractions, as well as the density of the composite. The model predicts two cases of composite volumetric interaction separated by a transition fibre weight fraction, at which...

Three-dimensional x-ray tomography of crack-resistant composites: New paradigms for process optimization

Energy Technology Data Exchange (ETDEWEB)

Kinney, J.H.; Haupt, D.L. [Lawrence Livermore National Laboratory, CA (United States)

1995-05-01

The goal of this research is to apply noninvasive, volumetric imaging technology (the x-ray tomographic microscope) to the characterization and process-modeling of ceramic matrix composites. Specifically, we propose to follow the evolution of a composite`s microstructure during chemical vapor infiltration processing, and relate the microstructure to processing parameters and fiber architecture. The results will be used to provide the fundamental and practical understanding necessary for cost-effective intelligent processing of ceramic matrix composites.

Unbounded weighted composition operators in L²-spaces

CERN Document Server

Budzyński, Piotr; Jung, Il Bong; Stochel, Jan

2018-01-01

This book establishes the foundations of the theory of bounded and unbounded weighted composition operators in L²-spaces. It develops the theory in full generality, meaning that the weighted composition operators under consideration are not regarded as products of multiplication and composition operators. A variety of seminormality properties are characterized and the first-ever criteria for subnormality of unbounded weighted composition operators is provided. The subtle interplay between the classical moment problem, graph theory and the injectivity problem is revealed and there is an investigation of the relationships between weighted composition operators and the corresponding multiplication and composition operators. The optimality of the obtained results is illustrated by a variety of examples, including those of discrete and continuous types. The book is primarily aimed at researchers in single or multivariable operator theory.

A Matrix Splitting Method for Composite Function Minimization

KAUST Repository

Yuan, Ganzhao

2016-12-07

Composite function minimization captures a wide spectrum of applications in both computer vision and machine learning. It includes bound constrained optimization and cardinality regularized optimization as special cases. This paper proposes and analyzes a new Matrix Splitting Method (MSM) for minimizing composite functions. It can be viewed as a generalization of the classical Gauss-Seidel method and the Successive Over-Relaxation method for solving linear systems in the literature. Incorporating a new Gaussian elimination procedure, the matrix splitting method achieves state-of-the-art performance. For convex problems, we establish the global convergence, convergence rate, and iteration complexity of MSM, while for non-convex problems, we prove its global convergence. Finally, we validate the performance of our matrix splitting method on two particular applications: nonnegative matrix factorization and cardinality regularized sparse coding. Extensive experiments show that our method outperforms existing composite function minimization techniques in term of both efficiency and efficacy.

A Matrix Splitting Method for Composite Function Minimization

KAUST Repository

Yuan, Ganzhao; Zheng, Wei-Shi; Ghanem, Bernard

2016-01-01

Composite function minimization captures a wide spectrum of applications in both computer vision and machine learning. It includes bound constrained optimization and cardinality regularized optimization as special cases. This paper proposes and analyzes a new Matrix Splitting Method (MSM) for minimizing composite functions. It can be viewed as a generalization of the classical Gauss-Seidel method and the Successive Over-Relaxation method for solving linear systems in the literature. Incorporating a new Gaussian elimination procedure, the matrix splitting method achieves state-of-the-art performance. For convex problems, we establish the global convergence, convergence rate, and iteration complexity of MSM, while for non-convex problems, we prove its global convergence. Finally, we validate the performance of our matrix splitting method on two particular applications: nonnegative matrix factorization and cardinality regularized sparse coding. Extensive experiments show that our method outperforms existing composite function minimization techniques in term of both efficiency and efficacy.

Composite wind turbine towers

Energy Technology Data Exchange (ETDEWEB)

Polyzois, D. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Civil Engineering

2008-07-01

This paper discussed experiments conducted to optimized the advanced composite materials such as fiberglass reinforced plastics (FRP) used to fabricate wind turbine towers. FRP materials are used in tubular steel, lattice, guyed, and reinforced concrete towers. The towers and turbine blades are transported in segments and assembled on-site, sometimes in offshore or remote locations.The FRP composites are used to build towers with a high strength-to-weight ratio as well as to provide resistance to chemical attacks and corrosion. Use of the materials has resulted in towers that do not require heavy installation equipment. Experimental programs were conducted to verify the structural behaviour of the tower structure's individual-scaled cells as well as to evaluate the performance of multi-cell assemblies. Joint assembly designs were optimized, and a filament winding machine was used to conduct the experimental study and to test individual cells. Failure mode analyses were conducted to determine local buckling and shear rupture. Tension, compression, and shear properties of the FRP materials were tested experimentally, and data from the test were then used to develop finite element models of the composite towers as well as to obtain load deflection curves and tip oscillation data. A case study of a 750 kW wind turbine in Churchill, Manitoba was used to test the design. tabs., figs.

Central composite design and genetic algorithm applied for the optimization of ultrasonic-assisted removal of malachite green by ZnO Nanorod-loaded activated carbon

Science.gov (United States)

Ghaedi, M.; Azad, F. Nasiri; Dashtian, K.; Hajati, S.; Goudarzi, A.; Soylak, M.

2016-10-01

Maximum malachite green (MG) adsorption onto ZnO Nanorod-loaded activated carbon (ZnO-NR-AC) was achieved following the optimization of conditions, while the mass transfer was accelerated by ultrasonic. The central composite design (CCD) and genetic algorithm (GA) were used to estimate the effect of individual variables and their mutual interactions on the MG adsorption as response and to optimize the adsorption process. The ZnO-NR-AC surface morphology and its properties were identified via FESEM, XRD and FTIR. The adsorption equilibrium isotherm and kinetic models investigation revealed the well fit of the experimental data to Langmuir isotherm and pseudo-second-order kinetic model, respectively. It was shown that a small amount of ZnO-NR-AC (with adsorption capacity of 20 mg g- 1) is sufficient for the rapid removal of high amount of MG dye in short time (3.99 min).

Machining of Metal Matrix Composites

CERN Document Server

2012-01-01

Machining of Metal Matrix Composites provides the fundamentals and recent advances in the study of machining of metal matrix composites (MMCs). Each chapter is written by an international expert in this important field of research. Machining of Metal Matrix Composites gives the reader information on machining of MMCs with a special emphasis on aluminium matrix composites. Chapter 1 provides the mechanics and modelling of chip formation for traditional machining processes. Chapter 2 is dedicated to surface integrity when machining MMCs. Chapter 3 describes the machinability aspects of MMCs. Chapter 4 contains information on traditional machining processes and Chapter 5 is dedicated to the grinding of MMCs. Chapter 6 describes the dry cutting of MMCs with SiC particulate reinforcement. Finally, Chapter 7 is dedicated to computational methods and optimization in the machining of MMCs. Machining of Metal Matrix Composites can serve as a useful reference for academics, manufacturing and materials researchers, manu...

NUTRIENT COMPOSITION OF NIGER SEED (GUIZOTIA ...

African Journals Online (AJOL)

B. S. Chandravanshi

fiber. Niger oil has a fatty acid composition typical for seed oils of the .... system using external calibration curve after optimizing the parameters in to .... physical and chemical properties of the soil, application of natural (manure) and artificial.

Soil attributes drive nest-site selection by the campo miner Geositta poeciloptera

Science.gov (United States)

Teixeira, João Paulo Gusmão; Solar, Ricardo; Vasconcelos, Bruno Nery F.; Fernandes, Raphael B. A.; Lopes, Leonardo Esteves

2018-01-01

Substrate type is a key-factor in nest-site selection and nest architecture of burrowing birds. However, little is known about which factors drive nest-site selection for these species, especially in the tropics. We studied the influence of soil attributes on nest-site selection by the campo miner Geositta poeciloptera, an open grassland bird that builds its nests within soil cavities. For all nests found, we measured the depth of the nest cavity and the resistance of the soil to penetration, and identified the soil horizon in which the nest was located. In soil banks with nests, we collected soil samples for granulometric analysis around each nest cavity, while in soil banks without nests we collected these samples at random points. From 43 nests found, 86% were located in the deeper soil horizons (C-horizon), and only 14% in the shallower horizons (B-horizon). Granulometric analysis showed that the C-horizons possessed a high similar granulometric composition, with high silt and low clay contents. These characteristics are associated with a low degree of structural development of the soil, which makes it easier to excavate. Contrarily, soil resistance to penetration does not seem to be an important criterion for nest site selection, although nests in more resistant the soils tend to have shallower nest cavities. Among the soil banks analyzed, 40% of those without cavities possessed a larger proportion of B-horizon relative to the C-horizon, and their texture was more clayey. On the other hand, almost all soil banks containing nest cavities had a larger C-horizon and a silty texture, indicating that soil attributes drive nest-site selection by G. poeciloptera. Thus, we conclude that the patchy distribution of G. poeciloptera can attributed to the infrequent natural exposure of the C-horizon in the tropical region, where well developed, deep and permeable soils are more common. PMID:29381768

Soil attributes drive nest-site selection by the campo miner Geositta poeciloptera.

Science.gov (United States)

Meireles, Ricardo Camargos de; Teixeira, João Paulo Gusmão; Solar, Ricardo; Vasconcelos, Bruno Nery F; Fernandes, Raphael B A; Lopes, Leonardo Esteves

2018-01-01

Substrate type is a key-factor in nest-site selection and nest architecture of burrowing birds. However, little is known about which factors drive nest-site selection for these species, especially in the tropics. We studied the influence of soil attributes on nest-site selection by the campo miner Geositta poeciloptera, an open grassland bird that builds its nests within soil cavities. For all nests found, we measured the depth of the nest cavity and the resistance of the soil to penetration, and identified the soil horizon in which the nest was located. In soil banks with nests, we collected soil samples for granulometric analysis around each nest cavity, while in soil banks without nests we collected these samples at random points. From 43 nests found, 86% were located in the deeper soil horizons (C-horizon), and only 14% in the shallower horizons (B-horizon). Granulometric analysis showed that the C-horizons possessed a high similar granulometric composition, with high silt and low clay contents. These characteristics are associated with a low degree of structural development of the soil, which makes it easier to excavate. Contrarily, soil resistance to penetration does not seem to be an important criterion for nest site selection, although nests in more resistant the soils tend to have shallower nest cavities. Among the soil banks analyzed, 40% of those without cavities possessed a larger proportion of B-horizon relative to the C-horizon, and their texture was more clayey. On the other hand, almost all soil banks containing nest cavities had a larger C-horizon and a silty texture, indicating that soil attributes drive nest-site selection by G. poeciloptera. Thus, we conclude that the patchy distribution of G. poeciloptera can attributed to the infrequent natural exposure of the C-horizon in the tropical region, where well developed, deep and permeable soils are more common.

Development of semiindustrial technology for electrolytic powder production

International Nuclear Information System (INIS)

Suchkov, A.B.; Kovalev, B.F.; Zhbanov, A.M.; Rabinovich, E.M.; Sozina, A.L.

1978-01-01

The technology of the production of Fe, Mn, Cr, W pure metal powders by electrolysis of industrial waste in molten chloride-fluoride media with the addition of lower chlorides of refining metal was tested in laboratory and then in industrial electrolysers (2kA). The cathode deposit was subjected to hydrometallurgical treatment. Approximate technological parameters of electrorefining are presented. A high-temperature (700-1000 deg C) hydrogen annealing was applied to increase the quality and to change physicochemical and technological characteristics of electrolytic powders. The data on the chemical composition of Mowders are presented, testifying to their high purity. It is shown that electrolytic powders are not uniform in granulometric composition (from 1 to 100 μm), their particles being characterized mainly by the dendrite structure

Transportation package design using numerical optimization

International Nuclear Information System (INIS)

Harding, D.C.; Witkowski, W.R.

1993-01-01

Since the design of transportation packages involves a complex coupling of structural, thermal and radiation shielding analyses and must follow very strict design constraints, numerical optimization provides the potential for more efficient container designs. In numerical optimization, the requirements of the design problem are mathematically formulated through the use of an objective function and constraints. The objective function(s), e.g., package weight, cost, volume, or combination thereof, is the function to be minimized or maximized by altering a set of design variables that define the package's shape and dimensions. Constraints are limitations on the performance of the system, such as resisting structural and thermal accident environments. Two constraints defined for an example wire mesh composite Type B package are: 1) deformation in the containment vessel seal region remains small enough throughout the 10 CFR-71 accident conditions to meet containment criteria, and 2) the elastomeric seal region remains below its operational temperature limit to guarantee seal integrity in the fire environment. The first constraint of a minimum energy absorbing layer thickness is evaluated with finite element analyses of the proposed dynamic crush accident criteria. The second constraint is evaluated with a 1-D transient thermal finite difference code parametrized for variable composite layer thicknesses, and is integrated with the optimization process. (J.P.N.)

Combinatorial thin film materials science: From alloy discovery and optimization to alloy design

Energy Technology Data Exchange (ETDEWEB)

Gebhardt, Thomas, E-mail: gebhardt@mch.rwth-aachen.de; Music, Denis; Takahashi, Tetsuya; Schneider, Jochen M.

2012-06-30

This paper provides an overview of modern alloy development, from discovery and optimization towards alloy design, based on combinatorial thin film materials science. The combinatorial approach, combining combinatorial materials synthesis of thin film composition-spreads with high-throughput property characterization has proven to be a powerful tool to delineate composition-structure-property relationships, and hence to efficiently identify composition windows with enhanced properties. Furthermore, and most importantly for alloy design, theoretical models and hypotheses can be critically appraised. Examples for alloy discovery, optimization, and alloy design of functional as well as structural materials are presented. Using Fe-Mn based alloys as an example, we show that the combination of modern electronic-structure calculations with the highly efficient combinatorial thin film composition-spread method constitutes an effective tool for knowledge-based alloy design.

Hydrogen production by onboard gasoline processing – Process simulation and optimization

Energy Technology Data Exchange (ETDEWEB)

Bisaria, Vega; Smith, R.J. Byron,

2013-12-15

Highlights: • Process flow sheet for an onboard fuel processor for 100 kW fuel cell output was simulated. • Gasoline fuel requirement was found to be 30.55 kg/hr. • The fuel processor efficiency was found to be 95.98%. • An heat integrated optimum flow sheet was developed. - Abstract: Fuel cell vehicles have reached the commercialization stage and hybrid vehicles are already on the road. While hydrogen storage and infrastructure remain critical issues in stand alone commercialization of the technology, researchers are developing onboard fuel processors, which can convert a variety of fuels into hydrogen to power these fuel cell vehicles. The feasibility study of a 100 kW on board fuel processor based on gasoline fuel is carried out using process simulation. The steady state model has been developed with the help of Aspen HYSYS to analyze the fuel processor and total system performance. The components of the fuel processor are the fuel reforming unit, CO clean-up unit and auxiliary units. Optimization studies were carried out by analyzing the influence of various operating parameters such as oxygen to carbon ratio, steam to carbon ratio, temperature and pressure on the process equipments. From the steady state model optimization using Aspen HYSYS, an optimized reaction composition in terms of hydrogen production and carbon monoxide concentration corresponds to: oxygen to carbon ratio of 0.5 and steam to carbon ratio of 0.5. The fuel processor efficiency of 95.98% is obtained under these optimized conditions. The heat integration of the system using the composite curve, grand composite curve and utility composite curve were studied for the system. The most appropriate heat exchanger network from the generated ones was chosen and that was incorporated into the optimized flow sheet of the100 kW fuel processor. A completely heat integrated 100 kW fuel processor flow sheet using gasoline as fuel was thus successfully simulated and optimized.

Hydrogen production by onboard gasoline processing – Process simulation and optimization

International Nuclear Information System (INIS)

Bisaria, Vega; Smith, R.J. Byron

2013-01-01

Highlights: • Process flow sheet for an onboard fuel processor for 100 kW fuel cell output was simulated. • Gasoline fuel requirement was found to be 30.55 kg/hr. • The fuel processor efficiency was found to be 95.98%. • An heat integrated optimum flow sheet was developed. - Abstract: Fuel cell vehicles have reached the commercialization stage and hybrid vehicles are already on the road. While hydrogen storage and infrastructure remain critical issues in stand alone commercialization of the technology, researchers are developing onboard fuel processors, which can convert a variety of fuels into hydrogen to power these fuel cell vehicles. The feasibility study of a 100 kW on board fuel processor based on gasoline fuel is carried out using process simulation. The steady state model has been developed with the help of Aspen HYSYS to analyze the fuel processor and total system performance. The components of the fuel processor are the fuel reforming unit, CO clean-up unit and auxiliary units. Optimization studies were carried out by analyzing the influence of various operating parameters such as oxygen to carbon ratio, steam to carbon ratio, temperature and pressure on the process equipments. From the steady state model optimization using Aspen HYSYS, an optimized reaction composition in terms of hydrogen production and carbon monoxide concentration corresponds to: oxygen to carbon ratio of 0.5 and steam to carbon ratio of 0.5. The fuel processor efficiency of 95.98% is obtained under these optimized conditions. The heat integration of the system using the composite curve, grand composite curve and utility composite curve were studied for the system. The most appropriate heat exchanger network from the generated ones was chosen and that was incorporated into the optimized flow sheet of the100 kW fuel processor. A completely heat integrated 100 kW fuel processor flow sheet using gasoline as fuel was thus successfully simulated and optimized

Damage tolerance optimization of composite stringer run-out under tensile load

DEFF Research Database (Denmark)

Badalló, Pere; Trias, Daniel; Lindgaard, Esben

2015-01-01

. The influence of some geometric variables of the run-out in the interface of the set stringer-panel is crucial to avoid the onset and growth of delamination cracks. In this study, a damage tolerant design of a stringer run-out is achieved by a process of design optimization and surrogate modeling techniques....... A parametric finite element model created with python was used to generate a number of different geometrical designs of the stringer run-out. The relevant information of these models was adjusted using Radial Basis Functions (RBF). Finally, the optimization problem was solved using Quasi-Newton method...

Long-term lifestyle intervention with optimized high-intensity interval training improves body composition, cardiometabolic risk, and exercise parameters in patients with abdominal obesity.

Science.gov (United States)

Gremeaux, Vincent; Drigny, Joffrey; Nigam, Anil; Juneau, Martin; Guilbeault, Valérie; Latour, Elise; Gayda, Mathieu

2012-11-01

The aim of this study was to study the impact of a combined long-term lifestyle and high-intensity interval training intervention on body composition, cardiometabolic risk, and exercise tolerance in overweight and obese subjects. Sixty-two overweight and obese subjects (53.3 ± 9.7 yrs; mean body mass index, 35.8 ± 5 kg/m(2)) were retrospectively identified at their entry into a 9-mo program consisting of individualized nutritional counselling, optimized high-intensity interval exercise, and resistance training two to three times a week. Anthropometric measurements, cardiometabolic risk factors, and exercise tolerance were measured at baseline and program completion. Adherence rate was 97%, and no adverse events occurred with high-intensity interval exercise training. Exercise training was associated with a weekly energy expenditure of 1582 ± 284 kcal. Clinically and statistically significant improvements were observed for body mass (-5.3 ± 5.2 kg), body mass index (-1.9 ± 1.9 kg/m(2)), waist circumference (-5.8 ± 5.4 cm), and maximal exercise capacity (+1.26 ± 0.84 metabolic equivalents) (P high-density lipoprotein ratio were also significantly improved (P body mass and waist circumference loss were baseline body mass index and resting metabolic rate; those for body mass index decrease were baseline waist circumference and triglyceride/high-density lipoprotein cholesterol ratio. A long-term lifestyle intervention with optimized high-intensity interval exercise improves body composition, cardiometabolic risk, and exercise tolerance in obese subjects. This intervention seems safe, efficient, and well tolerated and could improve adherence to exercise training in this population.

THE CONCEPT OF USING EVOLUTIONARY ALGORITHMS AS TOOLS FOR OPTIMAL PLANNING OF MULTIMODAL COMPOSITION IN THE DIDACTIC TEXTS

Directory of Open Access Journals (Sweden)

Marek A. Jakubowski

2014-11-01

Full Text Available At the beginning we would like to provide a short description of the new theory of learning in the digital age called connectivism. It is the integration of principles explored by the following theories: chaos, network, complexity and self-organization. Next, we describe in short new visual solutions for the teaching of writing so called multimodal literacy 5–11. We define and describe the following notions: multimodal text and original theory so called NOS (non-optimum systems methodology as a basis for new methods of visual solutions at the classes and audiovisual texts applications. Especially, we would like to emphasize the tremendous usefulness of evolutionary algorithms VEGA and NSGA as tools for optimal planning of multimodal composition in teaching texts. Finally, we give some examples of didactic texts for classrooms, which provide a deep insight into learning skills and tasks needed in the Internet age.

Factors Defining Field Germination of Oilseed Radish Seeds

Directory of Open Access Journals (Sweden)

N.V. Dorofeev

2013-08-01

Full Text Available Influence of temperature, depth of crops and granulometric of soil structure on germination speed, laboratory and field germination of oilseed radish seeds were studied. It was established that the period of seed-germination is defined both by temperature and granulometric structure of soil. The highest field germination was marked on sandy loam at depth of crops' seeds at 3 cm and 20°С.

Wear rate optimization of Al/SiCnp/e-glass fibre hybrid metal matrix composites using Taguchi method and genetic algorithm and development of wear model using artificial neural networks

Science.gov (United States)

Bongale, Arunkumar M.; Kumar, Satish; Sachit, T. S.; Jadhav, Priya

2018-03-01

Studies on wear properties of Aluminium based hybrid nano composite materials, processed through powder metallurgy technique, are reported in the present study. Silicon Carbide nano particles and E-glass fibre are reinforced in pure aluminium matrix to fabricate hybrid nano composite material samples. Pin-on-Disc wear testing equipment is used to evaluate dry sliding wear properties of the composite samples. The tests were conducted following the Taguchi’s Design of Experiments method. Signal-to-Noise ratio analysis and Analysis of Variance are carried out on the test data to find out the influence of test parameters on the wear rate. Scanning Electron Microscopic analysis and Energy Dispersive x-ray analysis are conducted on the worn surfaces to find out the wear mechanisms responsible for wear of the composites. Multiple linear regression analysis and Genetic Algorithm techniques are employed for optimization of wear test parameters to yield minimum wear of the composite samples. Finally, a wear model is built by the application of Artificial Neural Networks to predict the wear rate of the composite material, under different testing conditions. The predicted values of wear rate are found to be very close to the experimental values with a deviation in the range of 0.15% to 8.09%.

Optimal Design of Variable Stiffness Composite Structures using Lamination Parameters

NARCIS (Netherlands)

IJsselmuiden, S.T.

2011-01-01

Fiber reinforced composite materials have gained widespread acceptance for a multitude of applications in the aerospace, automotive, maritime and wind-energy industries. Automated fiber placement technologies have developed rapidly over the past two decades, driven primarily by a need to reduce

Graphene Modified TiO2 Composite Photocatalysts: Mechanism, Progress and Perspective

Science.gov (United States)

Tang, Bo; Chen, Haiqun; Peng, Haoping; Wang, Zhengwei; Huang, Weiqiu

2018-01-01

Graphene modified TiO2 composite photocatalysts have drawn increasing attention because of their high performance. Some significant advancements have been achieved with the continuous research, such as the corresponding photocatalytic mechanism that has been revealed. Specific influencing factors have been discovered and potential optimizing methods are proposed. The latest developments in graphene assisted TiO2 composite photocatalysts are abstracted and discussed. Based on the primary reasons behind the observed phenomena of these composite photocatalysts, probable development directions and further optimizing strategies are presented. Moreover, several novel detective technologies—beyond the decomposition test—which can be used to judge the photocatalytic performances of the resulting photocatalysts are listed and analyzed. Although some objectives have been achieved, new challenges still exist and hinder the widespread application of graphene-TiO2 composite photocatalysts, which deserves further study. PMID:29439545

Determination of maximum negative Poisson's ratio for laminated fiber composites

Energy Technology Data Exchange (ETDEWEB)

Shokrieh, M.M.; Assadi, A. [Composites Research Laboratory, Mechanical Engineering Department, Center of Excellence in Experimental Solid Mechanics and Dynamics, Iran University of Science and Technology, Tehran 16846-13114 (Iran, Islamic Republic of)

2011-05-15

Contrary to isotropic materials, composites always show complicated mechanical behavior under external loadings. In this article, an efficient algorithm is employed to obtain the maximum negative Poisson's ratio for laminated composite plates. We try to simplify the problem based on normalization of parameters and some manufacturing constraints to overlook the additional constraint of the optimization procedure. A genetic algorithm is used to find the optimal thickness of each lamina with a specified fiber direction. It is observed that the laminated composite with the configuration of (15/60/15) has the maximum negative Poisson's ratio. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Modelling and analysis of abrasive wear performance of composites ...

African Journals Online (AJOL)

It has been observed that fibre length plays a major role in wear phenomenon. The length of the fibre has been optimized using a popular evolutionary technique known as particle swarm optimization (PSO) and neural network. The study recommends that fibre length should be 7-8 mm for minimum wear of the composites.

Optimum design of laminated composite under axial compressive load

Indian Academy of Sciences (India)

In the present study optimal design of composite laminates, with and without rectangular cut-out, is carried out for maximizing the buckling load. Optimization study is carried out for obtaining the maximum buckling load with design variables as ply thickness, cut-out size and orientation of cut-out with respect to laminate.

Optimization of vegetable milk extraction from whole and dehulled Mucuna pruriens (Var Cochinchinensis) flours using central composite design.

Science.gov (United States)

Mang, Dimitry Y; Abdou, Armand B; Njintang, Nicolas Y; Djiogue, Edith J M; Panyo, Emmanuel A; Bernard, Clemence; Ndjouenkeu, Robert; Loura, Benoît B; Mbofung, Carl M F

2016-01-01

Extraction conditions for maximum values of protein yield, protein content, sugar content and dry matter of vegetable milk extracts from dehulled Mucuna cochinchinensis bean flour and whole Mucuna cochinchinensis bean flour were investigated using response surface methodology. A Central Composite Design (CCFD) with three factors: temperature (25 to 95 °C); extraction time (6 to 74 min.) and water to flour ratio (6 to 24 mL/g) were used. Data analysis showed that all the factors significantly (p < 0.05) affected the responses variables. The optimal conditions determined for extraction were temperature 63-66 °C, water to flour ratio 12-13 mL/g and extraction time of 57-67 min. At these optimum points the protein and sugar contents, extraction yield of protein and dry matter were respectively 14.0 g/100 mL, 4.8 g/100 mL, 53.8 g/100 g, 12.1 g/100 g for vegetable milk produced from dehulled M. cochinchinensis bean flour and 6.4 g/100 mL, 3.5 g/100 mL, 50.0 g/100 g and 8.0 g/100 g for vegetable milk extracted from whole M. cochinchinensis bean flour milk. The optimal condition was verified at the optimum points for model validation and the response values were not significantly different from the predicted values.

A hybrid, massively parallel implementation of a genetic algorithm for optimization of the impact performance of a metal/polymer composite plate

KAUST Repository

Narayanan, Kiran

2012-07-17

A hybrid parallelization method composed of a coarse-grained genetic algorithm (GA) and fine-grained objective function evaluations is implemented on a heterogeneous computational resource consisting of 16 IBM Blue Gene/P racks, a single x86 cluster node and a high-performance file system. The GA iterator is coupled with a finite-element (FE) analysis code developed in house to facilitate computational steering in order to calculate the optimal impact velocities of a projectile colliding with a polyurea/structural steel composite plate. The FE code is capable of capturing adiabatic shear bands and strain localization, which are typically observed in high-velocity impact applications, and it includes several constitutive models of plasticity, viscoelasticity and viscoplasticity for metals and soft materials, which allow simulation of ductile fracture by void growth. A strong scaling study of the FE code was conducted to determine the optimum number of processes run in parallel. The relative efficiency of the hybrid, multi-level parallelization method is studied in order to determine the parameters for the parallelization. Optimal impact velocities of the projectile calculated using the proposed approach, are reported. © The Author(s) 2012.

Cutting forces optimization in the turning of UD-GFRP composites ...

African Journals Online (AJOL)

user

use of composites has grown considerably, particularly in the aerospace, aircraft, automobile, sporting goods, transportation, power generation and marine industries. Machining of these materials poses particular problems that are seldom seen with metals due to the inhomogeneity, anisotropy and abrasive characteristics ...

Occurrence of polycyclic aromatic hydrocarbons in dust emitted from circulating fluidized bed boilers.

Science.gov (United States)

Kozielska, B; Konieczyńiski, J

2008-11-01

Occurrence of polycyclic aromatic hydrocarbons (PAHs) in granulometric fractions of dust emitted from a hard coal fired circulating fluidized bed (CFB) boiler was investigated. The dust was sampled with the use of a Mark III impactor. In each fraction of dust, by using gas chromatography (GC), 16 selected PAHs and total PAHs were determined and the toxic equivalent B(a)P (TE B(a)P) was computed. The results, recalculated for the standard granulometric fractions, are presented as concentrations and content of the determined PAHs in dust. Distributions of PAHs and their profiles in the granulometric dust fractions were studied also. The PAHs in dust emitted from the CFB boiler were compared with those emitted from mechanical grate boilers; a distinctly lower content of PAHs was found in dust emitted from the former.

Optimization of waste loading in high-level glass in the presence of uncertainty

International Nuclear Information System (INIS)

Hoza, M.; Fann, G.I.; Hopkins, D.F.

1995-02-01

Hanford high-level liquid waste will be converted into a glass form for long-term storage. The glass must meet certain constraints on its composition and properties in order to have desired properties for processing (e.g., electrical conductivity, viscosity, and liquidus temperature) and acceptable durability for long-term storage. The Optimal Waste Loading (OWL) models, based on rigorous mathematical optimization techniques, have been developed to minimize the number of glass logs required and determine glass-former compositions that will produce a glass meeting all relevant constraints. There is considerable uncertainty in many of the models and data relevant to the formulation of high-level glass. In this paper, we discuss how we handle uncertainty in the glass property models and in the high-level waste composition to the vitrification process. Glass property constraints used in optimization are inequalities that relate glass property models obtained by regression analysis of experimental data to numerical limits on property values. Therefore, these constraints are subject to uncertainty. The sampling distributions of the regression models are used to describe the uncertainties associated with the constraints. The optimization then accounts for these uncertainties by requiring the constraints to be satisfied within specified confidence limits. The uncertainty in waste composition is handled using stochastic optimization. Given means and standard deviations of component masses in the high-level waste stream, distributions of possible values for each component are generated. A series of optimization runs is performed; the distribution of each waste component is sampled for each run. The resultant distribution of solutions is then statistically summarized. The ability of OWL models to handle these forms of uncertainty make them very useful tools in designing and evaluating high-level waste glasses formulations

Reinforcement Learning Based Web Service Compositions for Mobile Business

Science.gov (United States)

Zhou, Juan; Chen, Shouming

In this paper, we propose a new solution to Reactive Web Service Composition, via molding with Reinforcement Learning, and introducing modified (alterable) QoS variables into the model as elements in the Markov Decision Process tuple. Moreover, we give an example of Reactive-WSC-based mobile banking, to demonstrate the intrinsic capability of the solution in question of obtaining the optimized service composition, characterized by (alterable) target QoS variable sets with optimized values. Consequently, we come to the conclusion that the solution has decent potentials in boosting customer experiences and qualities of services in Web Services, and those in applications in the whole electronic commerce and business sector.

Fatty Acid Composition and Antioxidant Activity of Tea (Camellia sinensis L.) Seed Oil Extracted by Optimized Supercritical Carbon Dioxide

Science.gov (United States)

Wang, Yuefei; Sun, Da; Chen, Hao; Qian, Lisheng; Xu, Ping

2011-01-01

Seeds are another product in addition to leaves (raw materials for teas) of tea (Camellia sinensis L.) plant. The great increase of tea consumption in recent years raises the challenge of finding commercial applications for tea seeds. In the present study, supercritical carbon dioxide (SC-CO2) extraction edible oil from tea seed was carried out, response surface methodology (RSM) was used to optimize processing parameters including time (20–90 min), temperature (35–45 °C) and pressure (50–90 MPa). The fatty acid composition and antioxidant activity of the extracted oil was also investigated. The highest yield of oil (29.2 ± 0.6%) was obtained under optimal SC-CO2 extraction conditions (45 °C, 89.7 min and 32 MPa, respectively), which was significantly higher (p Soxhlet extraction. Meanwhile, tea seed oil extracted by SC-CO2 contained approximately 80% unsaturated fatty acids and showed a much stronger scavenging ability on the DPPH radical than that extracted by Soxhlet. SC-CO2 is a promising alternative for efficient extraction of edible oil from tea seed. Moreover, tea seed oil extracted by SC-CO2 is highly edible and has good antioxidant activity, and therefore may play a potential role as a health-promoting food resource in human diets. PMID:22174626

Fatty acid composition and antioxidant activity of tea (Camellia sinensis L.) seed oil extracted by optimized supercritical carbon dioxide.

Science.gov (United States)

Wang, Yuefei; Sun, Da; Chen, Hao; Qian, Lisheng; Xu, Ping

2011-01-01

Seeds are another product in addition to leaves (raw materials for teas) of tea (Camellia sinensis L.) plant. The great increase of tea consumption in recent years raises the challenge of finding commercial applications for tea seeds. In the present study, supercritical carbon dioxide (SC-CO(2)) extraction edible oil from tea seed was carried out, response surface methodology (RSM) was used to optimize processing parameters including time (20-90 min), temperature (35-45 °C) and pressure (50-90 MPa). The fatty acid composition and antioxidant activity of the extracted oil was also investigated. The highest yield of oil (29.2 ± 0.6%) was obtained under optimal SC-CO(2) extraction conditions (45 °C, 89.7 min and 32 MPa, respectively), which was significantly higher (p < 0.05) than that (25.3 ± 1.0%) given by Soxhlet extraction. Meanwhile, tea seed oil extracted by SC-CO(2) contained approximately 80% unsaturated fatty acids and showed a much stronger scavenging ability on the DPPH radical than that extracted by Soxhlet. SC-CO(2) is a promising alternative for efficient extraction of edible oil from tea seed. Moreover, tea seed oil extracted by SC-CO(2) is highly edible and has good antioxidant activity, and therefore may play a potential role as a health-promoting food resource in human diets.

Optimization of the Büchi B-90 spray drying process using central composite design for preparation of solid dispersions.

Science.gov (United States)

Gu, Bing; Linehan, Brian; Tseng, Yin-Chao

2015-08-01

A central composite design approach was applied to study the effect of polymer concentration, inlet temperature and air flow rate on the spray drying process of the Büchi B-90 nano spray dryer (B-90). Hypromellose acetate succinate-LF was used for the Design of Experiment (DoE) study. Statistically significant models to predict the yield, spray rate, and drying efficiency were generated from the study. The spray drying conditions were optimized according to the models to maximize the yield and efficiency of the process. The models were further validated using a poorly water-soluble investigational compound (BI064) from Boehringer Ingelheim Pharmaceuticals. The polymer/drug ratio ranged from 1/1 to 3/1w/w. The spray dried formulations were amorphous determined by differential scanning calorimetry and X-ray powder diffraction. The particle size of the spray dried formulations was 2-10 μm under polarized light microscopy. All the formulations were physically stable for at least 3h when suspended in an aqueous vehicle composed of 1% methyl cellulose. This study demonstrates that DoE is a useful tool to optimize the spray drying process, and the B-90 can be used to efficiently produce amorphous solid dispersions with a limited quantity of drug substance available during drug discovery stages. Copyright © 2015 Elsevier B.V. All rights reserved.

Fatty Acid Composition and Antioxidant Activity of Tea (Camellia sinensis L. Seed Oil Extracted by Optimized Supercritical Carbon Dioxide

Directory of Open Access Journals (Sweden)

Ping Xu

2011-11-01

Full Text Available Seeds are another product in addition to leaves (raw materials for teas of tea (Camellia sinensis L. plant. The great increase of tea consumption in recent years raises the challenge of finding commercial applications for tea seeds. In the present study, supercritical carbon dioxide (SC-CO2 extraction edible oil from tea seed was carried out, response surface methodology (RSM was used to optimize processing parameters including time (20–90 min, temperature (35–45 °C and pressure (50–90 MPa. The fatty acid composition and antioxidant activity of the extracted oil was also investigated. The highest yield of oil (29.2 ± 0.6% was obtained under optimal SC-CO2 extraction conditions (45 °C, 89.7 min and 32 MPa, respectively, which was significantly higher (p < 0.05 than that (25.3 ± 1.0% given by Soxhlet extraction. Meanwhile, tea seed oil extracted by SC-CO2 contained approximately 80% unsaturated fatty acids and showed a much stronger scavenging ability on the DPPH radical than that extracted by Soxhlet. SC-CO2 is a promising alternative for efficient extraction of edible oil from tea seed. Moreover, tea seed oil extracted by SC-CO2 is highly edible and has good antioxidant activity, and therefore may play a potential role as a health-promoting food resource in human diets.

Multiphase composites with extremal bulk modulus

DEFF Research Database (Denmark)

Gibiansky, L. V.; Sigmund, Ole

2000-01-01

are described. Most of our new results are related to the two-dimensional problem. A numerical topology optimization procedure that solves the inverse homogenization problem is adopted and used to look for two-dimensional three-phase composites with a maximal effective bulk modulus. For the combination...... isotropic three-dimensional three-phase composites with cylindrical inclusions of arbitrary cross-sections (plane strain problem) or transversely isotropic thin plates (plane stress or bending of plates problems). (C) 2000 Elsevier Science Ltd. All rights reserved....

First records of Freshwater Bivalves of Ilha Grande National Park, Paraná, Brazil

Directory of Open Access Journals (Sweden)

Flávio Henrique Ragonha

2014-03-01

Full Text Available The Ilha Grande National Park, Paraná, Brazil, is located in the Upper Paraná River and has characteristics typical of a floodplains. This protected area includes lagoons connected and disconnected to the Paraná River, although the latter also connect during periods of high water level, thus composing a heterogeneous group of lacustrine environments. The enormous potential the flora and fauna diversities are still little known to the region, as can be seen through benthic invertebrates, inclunding bivalves mollusks. The granulometric composition of these floodplain lagoons was formed mainly by mud and very fine sand. Furthermore, organic matter composition was predominantly of fine particulate. The other abiotic factors differed from lagoons located within the island of the park to those located in the left margin of Paraná River. The results demonstrated the importance of abiotic factors such as the physical composition of granulometric texture, organic matter and macrophyte banks, to the establishment of bivalves in these floodplain lagoons. We recorded bivalves of Pisidium (native, Diplodon (native, and Corbicula (invasive. The highest values of Diplodon sp. density were observed at São João/C lake, for Pisidium sterkianum (Pilsbry, 1897 at São João/M lake, and to Jatobá/C lagoon with high density of invasive species Corbicula fluminea (Müller, 1774. This study to obtain conduct the first records of freshwater bivalves in floodplains lagoon in the Ilha Grande National Park, and provides contributions to better understanding the ecology of these mollusks. The recording of native species in the region of Upper Paraná River floodplain after a lomg period without new records, demonstrated the importance of protecting the lagoons of the Ilha Grande National Park as they can be a possible refuge to some species of native freshwater bivalves.

Applying Central Composite Design and Response Surface Methodology to Optimize Growth and Biomass Production of Haemophilus influenzae Type b.

Science.gov (United States)

Momen, Seyed Bahman; Siadat, Seyed Davar; Akbari, Neda; Ranjbar, Bijan; Khajeh, Khosro

2016-06-01

Haemophilus influenzae type b (Hib) is the leading cause of bacterial meningitis, otitis media, pneumonia, cellulitis, bacteremia, and septic arthritis in infants and young children. The Hib capsule contains the major virulence factor, and is composed of polyribosyl ribitol phosphate (PRP) that can induce immune system response. Vaccines consisting of Hib capsular polysaccharide (PRP) conjugated to a carrier protein are effective in the prevention of the infections. However, due to costly processes in PRP production, these vaccines are too expensive. To enhance biomass, in this research we focused on optimizing Hib growth with respect to physical factors such as pH, temperature, and agitation by using a response surface methodology (RSM). We employed a central composite design (CCD) and a response surface methodology to determine the optimum cultivation conditions for growth and biomass production of H. influenzae type b. The treatment factors investigated were initial pH, agitation, and temperature, using shaking flasks. After Hib cultivation and determination of dry biomass, analysis of experimental data was performed by the RSM-CCD. The model showed that temperature and pH had an interactive effect on Hib biomass production. The dry biomass produced in shaking flasks was about 5470 mg/L, which was under an initial pH of 8.5, at 250 rpm and 35° C. We found CCD and RSM very effective in optimizing Hib culture conditions, and Hib biomass production was greatly influenced by pH and incubation temperature. Therefore, optimization of the growth factors to maximize Hib production can lead to 1) an increase in bacterial biomass and PRP productions, 2) lower vaccine prices, 3) vaccination of more susceptible populations, and 4) lower risk of Hib infections.

Application of rotatable central composite design in the preparation and optimization of poly(lactic-co-glycolic acid) nanoparticles for controlled delivery of paclitaxel.

Science.gov (United States)

Kollipara, Sivacharan; Bende, Girish; Movva, Snehalatha; Saha, Ranendra

2010-11-01

Polymeric carrier systems of paclitaxel (PCT) offer advantages over only available formulation Taxol® in terms of enhancing therapeutic efficacy and eliminating adverse effects. The objective of the present study was to prepare poly (lactic-co-glycolic acid) nanoparticles containing PCT using emulsion solvent evaporation technique. Critical factors involved in the processing method were identified and optimized by scientific, efficient rotatable central composite design aiming at low mean particle size and high entrapment efficiency. Twenty different experiments were designed and each formulation was evaluated for mean particle size and entrapment efficiency. The optimized formulation was evaluated for in vitro drug release, and absorption characteristics were studied using in situ rat intestinal permeability study. Amount of polymer and duration of ultrasonication were found to have significant effect on mean particle size and entrapment efficiency. First-order interactions of amount of miglyol with amount of polymer were significant in case of mean particle size, whereas second-order interactions of polymer were significant in mean particle size and entrapment efficiency. The developed quadratic model showed high correlation (R(2) > 0.85) between predicted response and studied factors. The optimized formulation had low mean particle size (231.68 nm) and high entrapment efficiency (95.18%) with 4.88% drug content. The optimized formulation showed controlled release of PCT for more than 72 hours. In situ absorption study showed faster and enhanced extent of absorption of PCT from nanoparticles compared to pure drug. The poly (lactic-co-glycolic acid) nanoparticles containing PCT may be of clinical importance in enhancing its oral bioavailability.

Multielemental characterization of sediments from rivers and reservoirs of a sediment quality monitoring network of Sao Paulo state, Brazil

Energy Technology Data Exchange (ETDEWEB)

Soares, Walace A.A.; Quinaglia, Gilson A., E-mail: wasoares@sp.gov.br, E-mail: gquinaglia@sp.gov.br [Companhia Ambiental do Estado de Sao Paulo (CETESB), SP (Brazil). Setor de Analises Toxicologicas; Favaro, Deborah I.T., E-mail: defavaro@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (LAN/CRPq/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Lab. de Analise por Ativacao Neutronica

2013-07-01

The Environment Company of the State of Sao Paulo (CETESB) by means of its quality monitoring network does, systematically, the assessment of water and sediment quality in rivers and reservoirs in the Sao Paulo state. The quality evaluation is done by means 50 parameters in water and 63 for sediment that are considered the more representative for CETESB monitoring. In 2011 the network monitoring analyzed 420 points being 24 in sediments. In the present study the multielemental characterization (total concentration) of 13 sediment samples from 24 rivers and reservoirs belonging to the CETESB monitoring network were analyzed by instrumental neutron activation analysis (INAA). The analytical validation according to precision and accuracy was checked through certified reference materials analyzes BEN (Basalt-IWG-GIT), SL-1 (Lake Sediment - IAEA) and Soil-5 (IAEA), that presents certified concentration values for all elements analyzed. The results obtained for multielemental characterization were compared to NASC values (North American Shale Composite) and the enrichment factor (EF) by using Sc as a normalizer element was calculated. The results showed higher enrichment values for As, Br, Cr, Hf, Ta, Th , U and Zn and rare earth elements (REE) Ce, Eu, La, Nd, Sm, Tb and Yb in many of the tested sediment samples indicating that there may be an anthropogenic contribution for these elements. The multielemental results were also compared to the granulometric composition of the sediment samples. Factorial and Cluster Analysis were applied and indicated that the elements distribution is controlled, mainly by the granulometric fractions of the sediments. (author)

Multielemental characterization of sediments from rivers and reservoirs of a sediment quality monitoring network of Sao Paulo state, Brazil

International Nuclear Information System (INIS)

Soares, Walace A.A.; Quinaglia, Gilson A.; Favaro, Deborah I.T.

2013-01-01

The Environment Company of the State of Sao Paulo (CETESB) by means of its quality monitoring network does, systematically, the assessment of water and sediment quality in rivers and reservoirs in the Sao Paulo state. The quality evaluation is done by means 50 parameters in water and 63 for sediment that are considered the more representative for CETESB monitoring. In 2011 the network monitoring analyzed 420 points being 24 in sediments. In the present study the multielemental characterization (total concentration) of 13 sediment samples from 24 rivers and reservoirs belonging to the CETESB monitoring network were analyzed by instrumental neutron activation analysis (INAA). The analytical validation according to precision and accuracy was checked through certified reference materials analyzes BEN (Basalt-IWG-GIT), SL-1 (Lake Sediment - IAEA) and Soil-5 (IAEA), that presents certified concentration values for all elements analyzed. The results obtained for multielemental characterization were compared to NASC values (North American Shale Composite) and the enrichment factor (EF) by using Sc as a normalizer element was calculated. The results showed higher enrichment values for As, Br, Cr, Hf, Ta, Th , U and Zn and rare earth elements (REE) Ce, Eu, La, Nd, Sm, Tb and Yb in many of the tested sediment samples indicating that there may be an anthropogenic contribution for these elements. The multielemental results were also compared to the granulometric composition of the sediment samples. Factorial and Cluster Analysis were applied and indicated that the elements distribution is controlled, mainly by the granulometric fractions of the sediments. (author)

Influence of coprecipitation and mechanical mixture methods on the characteristics of nickel oxide-alumina composites; Influencia dos metodos de coprecipitacao e mistura mecanica nas caracteristicas de compositos oxido de niquel-alumina

Energy Technology Data Exchange (ETDEWEB)

Cordeiro, G.L.; Yoshito, W.K.; Ussui, V.; Lima, N.B. de; Lazar, D.R.R., E-mail: gcordeiro@usp.br [Instituto de Pesquisas Energeticas e Nucleares (CCTM/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia de Materiais

2014-07-01

Alumina-supported nickel catalysts are currently used in the reforming process due to low cost and high activity for hydrogen production from alcohols. In this work, the effect of preparation methods on nickel oxide-alumina based materials has been investigated. Nickel content was fixed at 15 wt%. Ceramic powders were obtained by coprecipitation in ammonia medium and mechanical mixture. Coprecipitated materials were calcined in air at 750 deg C to obtain the corresponding oxides. Materials obtained by mechanical mixture were prepared by wet milling of nickel oxide and alumina powders, both synthesized by precipitation and calcination in air at 450 and 750 deg C, respectively. Powders were characterized by X-ray diffraction, nitrogen gas sorption by applying the BET method, laser diffraction, scanning electron microscopy, electrophoretic mobility measurements for zeta potential determination and infrared spectroscopy. The results showed that coprecipitation method allowed the production of mixed oxides with high surface area (232,7 ± 3,2 m{sup 2}.g{sup -1}) and normal granulometric distribution while mechanical mixture led to the formation of materials constituted by gamma alumina and nickel oxide phases, with low surface area (136,2 ± 0,5 m{sup 2}.g{sup -1}) and bimodal granulometric distribution. (author)

Static Aeroelastic Optimization of Composite Wings with Variable Stiffness Laminates

NARCIS (Netherlands)

Dillinger, J.K.S.

2014-01-01

The application of composite material in load carrying structural components of an aircraft is rapidly gaining momentum. While part of the reason for this can certainly be attributed to an increasing confidence of designers in the new material as a result of growing experience, two other crucial

Composite Solid Fuel: Research of Formation Parameters

Directory of Open Access Journals (Sweden)

Tabakaev Roman

2016-01-01

Full Text Available Involving of local low-grade fuels resources in fuel and energy balance is actual question of research in the present. In this paper the possibility of processing low-grade fuel in the solid fuel composite was considered. The aim of the work is to define the optimal parameters for formation of the solid composite fuel. A result of researches determined that dextrin content in the binder allows to obtain solid composite fuel having the highest strength. The drying temperature for the various fuels was determined: for pellets production was 20-80 °C, for briquettes – 20-40 °C.

An Automated Analysis-Synthesis Package for Design Optimization ...

African Journals Online (AJOL)

90 standards is developed for the design optimization of framed structures - continuous beams, plane and space trusses and rigid frames, grids and composite truss-rigid frames. The package will enable the structural engineer to effectively and ...

Design and Manufacturing of Composite Tower Structure for Wind Turbine Equipment

Science.gov (United States)

Park, Hyunbum

2018-02-01

This study proposes the composite tower design process for large wind turbine equipment. In this work, structural design of tower and analysis using finite element method was performed. After structural design, prototype blade manufacturing and test was performed. The used material is a glass fiber and epoxy resin composite. And also, sand was used in the middle part. The optimized structural design and analysis was performed. The parameter for optimized structural design is weight reduction and safety of structure. Finally, structure of tower will be confirmed by structural test.

Development, nutritional evaluation and optimization of instant ...

African Journals Online (AJOL)

In this study, different instant porridges were formulated from broken fractions of rice blended with bambara groundnut flour through extrusion cooking. Response Surface Methodology (RSM) and Central Composite Rotatable Design (CCRD) were used to optimize the production variables. The objective was to locate the ...

Optimization of a blueprint for in vitro glycolysis by metabolic real-time analysis

NARCIS (Netherlands)

Bujara, Matthias; Schümperli, Michael; Pellaux, René; Heinemann, Matthias; Panke, Sven

Recruiting complex metabolic reaction networks for chemical synthesis has attracted considerable attention but frequently requires optimization of network composition and dynamics to reach sufficient productivity. As a design framework to predict optimal levels for all enzymes in the network is

Improved Artificial Fish Algorithm for Parameters Optimization of PID Neural Network

OpenAIRE

Jing Wang; Yourui Huang

2013-01-01

In order to solve problems such as initial weights are difficult to be determined, training results are easy to trap in local minima in optimization process of PID neural network parameters by traditional BP algorithm, this paper proposed a new method based on improved artificial fish algorithm for parameters optimization of PID neural network. This improved artificial fish algorithm uses a composite adaptive artificial fish algorithm based on optimal artificial fish and nearest artificial fi...

Optimal design of a composite space shield based on numerical simulations

International Nuclear Information System (INIS)

Son, Byung Jin; Yoo, Jeong Hoon; Lee, Min Hyung

2015-01-01

In this study, optimal design of a stuffed Whipple shield is proposed by using numerical simulations and new penetration criterion. The target model was selected based on the shield model used in the Columbus module of the international space station. Because experimental results can be obtained only in the low velocity region below 7 km/s, it is required to derive the Ballistic limit curve (BLC) in the high velocity region above 7 km/s by numerical simulation. AUTODYN-2D, the commercial hydro-code package, was used to simulate the nonlinear transient analysis for the hypervelocity impact. The Smoothed particle hydrodynamics (SPH) method was applied to projectile and bumper modeling to represent the debris cloud generated after the impact. Numerical simulation model and selected material properties were validated through a quantitative comparison between numerical and experimental results. A new criterion to determine whether the penetration occurs or not is proposed from kinetic energy analysis by numerical simulation in the velocity region over 7 km/s. The parameter optimization process was performed to improve the protection ability at a specific condition through the Design of experiment (DOE) method and the Response surface methodology (RSM). The performance of the proposed optimal design was numerically verified.

Enhancement of dissolution and oral bioavailability of lacidipine via pluronic P123/F127 mixed polymeric micelles: formulation, optimization using central composite design and in vivo bioavailability study.

Science.gov (United States)

Fares, Ahmed R; ElMeshad, Aliaa N; Kassem, Mohamed A A

2018-11-01

This study aims at preparing and optimizing lacidipine (LCDP) polymeric micelles using thin film hydration technique in order to overcome LCDP solubility-limited oral bioavailability. A two-factor three-level central composite face-centered design (CCFD) was employed to optimize the formulation variables to obtain LCDP polymeric micelles of high entrapment efficiency and small and uniform particle size (PS). Formulation variables were: Pluronic to drug ratio (A) and Pluronic P123 percentage (B). LCDP polymeric micelles were assessed for entrapment efficiency (EE%), PS and polydispersity index (PDI). The formula with the highest desirability (0.959) was chosen as the optimized formula. The values of the formulation variables (A and B) in the optimized polymeric micelles formula were 45% and 80%, respectively. Optimum LCDP polymeric micelles had entrapment efficiency of 99.23%, PS of 21.08 nm and PDI of 0.11. Optimum LCDP polymeric micelles formula was physically characterized using transmission electron microscopy. LCDP polymeric micelles showed saturation solubility approximately 450 times that of raw LCDP in addition to significantly enhanced dissolution rate. Bioavailability study of optimum LCDP polymeric micelles formula in rabbits revealed a 6.85-fold increase in LCDP bioavailability compared to LCDP oral suspension.

Precipitation of Calcium Carbonate in the Presence of Urea at 293 K and 343 K

Directory of Open Access Journals (Sweden)

Białowicz Katarzyna

2014-06-01

Full Text Available The results of the precipitation of calcium carbonate from a waste post-distillation liquid (DS and a sodium bicarbonate saturated solution – both from the Solvay method – in the presence of urea are presented. The investigation was carried out at 293 K and 343 K. Reagent dosage times of 1, 5, 10, 20 and 30 min, and urea concentrations of 5, 6 and 10 mol/dm3 were applied. The granulometric composition, the values of bulk and packing densities and the absorptiveness sorption of water and paraffin oil from the obtained calcium carbonate were investigated.

Software for selection of optimal layouts of fast reactors

International Nuclear Information System (INIS)

Geraskin, N.I.; Kuz'min, A.M.; Morin, D.V.

1983-01-01

A complex program for the calculation and optimization of a two-dimensional cylindrical fast reactor consisting of two axial layers and having up to 10 zones of different compositions in each layer is described. Search for optimal parameters is performed by the successive linearization method based on the small perturbation theory and linear programming. The complex program is written for the BESM-6 computer in the FORTRAN language

Spatial distribution of the assemblage of Chironomidae larvae (Diptera in five floodplain lakes from Ilha Grande National Park (Paraná - Mato Grosso do Sul State, Brazil - doi: 10.4025/actascibiolsci.v35i2.10799

Directory of Open Access Journals (Sweden)

Alice Michiyo Takeda

2013-05-01

Full Text Available Chironomidae larvae (Diptera are one of the most important families among aquatic insects due to the higher abundance and species richness, considered an important tool for ecological studies. This study evaluated the richness of Chironomidae assemblage and related the distribution with physical and chemical variables in five lakes of the Paraná river, in the Ilha Grande National Park. There were two samplings, one in the central region and another in the marginal area of the floodplain lakes. In each region were collected six samples, five for biological analysis and one for granulometric analysis. The granulometric composition and organic matter content were the principal variables influencing the density and richness of Chironomidae. The scores of the abiotic data distinguished the marginal lakes (São João, Jacaré and Xambrê from the island lakes (Saraiva and Jatobá. The same segregation was observed in the distribution of Chironomidae morphotypes, and environments with higher values of organic matter, presented the lowest density and taxa richness. Thus, in this study the environmental variables directly interfered in the distribution, abundance and richness of Chironomidae of the floodplain lakes from Ilha Grande National Park, contributing to the knowledge of the diversity of this group in this area.

Thermoelectric generator based on composites obtained by sintering of detonation nanodiamonds

Science.gov (United States)

Eidelman, E. D.; Meilakhs, A. P.; Semak, B. V.; Shakhov, F. M.

2017-11-01

A model of a thermoelectric generator is proposed, in which composite materials obtained by sintering diamond nanoparticles are used as the main component. To increase the useful conversion of heat into electric current, it is proposed to use the effect of electron drag by ballistic phonons. To reduce the ineffective heat spread, it is proposed to use the effect of thermal resistance of the boundaries between the graphite-like and diamond-like phases of the composite. An experimental confirmation of the existence of an optimal volume ratio between graphite-like and diamond-like phases of the composite is predicted and obtained. The highest achieved value of thermoelectric coefficient in the actual structure is 80 µV K-1 (which means 20 times increase compared to that of composites not of the optimal structure), with a thermal conductivity of 50 W m-1 K-1. These results were obtained with constant electrical conductivity. The combined influence of these two effects in case of the ideal composite structure should result in an increase of the thermoelectric efficiency parameter by three orders of magnitude.

Design of materials with extreme thermal expansion using a three-phase topology optimization method

DEFF Research Database (Denmark)

Sigmund, Ole; Torquato, S.

1997-01-01

Composites with extremal or unusual thermal expansion coefficients are designed using a three-phase topology optimization method. The composites are made of two different material phases and a void phase. The topology optimization method consists in finding the distribution of material phases...... materials having maximum directional thermal expansion (thermal actuators), zero isotropic thermal expansion, and negative isotropic thermal expansion. It is shown that materials with effective negative thermal expansion coefficients can be obtained by mixing two phases with positive thermal expansion...

Using the PSCPCSP computer software for optimization of the composition of industrial alloys and development of new high-temperature nickel-base alloys

Science.gov (United States)

Rtishchev, V. V.

1995-11-01

Using computer programs some foreign firms have developed new deformable and castable high-temperature nickel-base alloys such as IN, Rene, Mar-M, Udimet, TRW, TM, TMS, TUT, with equiaxial, columnar, and single-crystal structures for manufacturing functional and nozzle blades and other parts of the hot duct of transport and stationary gas-turbine installations (GTI). Similar investigations have been carried out in Russia. This paper presents examples of the use of the PSCPCSP computer software for a quantitative analysis of structural und phase characteristics and properties of industrial alloys with change (within the grade range) in the concentrations of the alloying elements for optimizing the composition of the alloys and regimes of their heat treatment.

Optimizing High Performance Self Compacting Concrete

Directory of Open Access Journals (Sweden)

Raymond A Yonathan

2017-01-01

Full Text Available This paper’s objectives are to learn the effect of glass powder, silica fume, Polycarboxylate Ether, and gravel to optimizing composition of each factor in making High Performance SCC. Taguchi method is proposed in this paper as best solution to minimize specimen variable which is more than 80 variations. Taguchi data analysis method is applied to provide composition, optimizing, and the effect of contributing materials for nine variable of specimens. Concrete’s workability was analyzed using Slump flow test, V-funnel test, and L-box test. Compressive and porosity test were performed for the hardened state. With a dimension of 100×200 mm the cylindrical specimens were cast for compressive test with the age of 3, 7, 14, 21, 28 days. Porosity test was conducted at 28 days. It is revealed that silica fume contributes greatly to slump flow and porosity. Coarse aggregate shows the greatest contributing factor to L-box and compressive test. However, all factors show unclear result to V-funnel test.

Modeling and Analysis of Composites Using Smart Materials and Optimization Techniques

National Research Council Canada - National Science Library

Chattopadhyay, A

2001-01-01

The vibratory load reduction at rotor hub using self-sensing piezoelectric material and closed loop control is investigated, A composite box beam theory is developed to model the primary load carrying...