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Reliability-based evaluation of design code provisions for circular concrete-filled steel columns

BECK, Andre T.; OLIVEIRA, Walter L. A. de; NARDIM, Silvana De; ELDEBS, Ana L. H. C.
Fonte: ELSEVIER SCI LTD Publicador: ELSEVIER SCI LTD
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.211572%
This paper presents an investigation of design code provisions for steel-concrete composite columns. The study covers the national building codes of United States, Canada and Brazil, and the transnational EUROCODE. The study is based on experimental results of 93 axially loaded concrete-filled tubular steel columns. This includes 36 unpublished, full scale experimental results by the authors and 57 results from the literature. The error of resistance models is determined by comparing experimental results for ultimate loads with code-predicted column resistances. Regression analysis is used to describe the variation of model error with column slenderness and to describe model uncertainty. The paper shows that Canadian and European codes are able to predict mean column resistance, since resistance models of these codes present detailed formulations for concrete confinement by a steel tube. ANSI/AISC and Brazilian codes have limited allowance for concrete confinement, and become very conservative for short columns. Reliability analysis is used to evaluate the safety level of code provisions. Reliability analysis includes model error and other random problem parameters like steel and concrete strengths, and dead and live loads. Design code provisions are evaluated in terms of sufficient and uniform reliability criteria. Results show that the four design codes studied provide uniform reliability...

Adaptable Strut-and-Tie Model for Design and Verification of Four-Pile Caps

SOUZA, Rafael; KUCHMA, Daniel; PARK, Jung Woong; Bittencourt, Tulio Nogueira
Fonte: AMER CONCRETE INST Publicador: AMER CONCRETE INST
Tipo: Artigo de Revista Científica
Português
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A large percentage of pile caps support only one column, and the pile caps in turn are supported by only a few piles. These are typically short and deep members with overall span-depth ratios of less than 1.5. Codes of practice do not provide uniform treatment for the design of these types of pile caps. These members have traditionally been designed as beams spanning between piles with the depth selected to avoid shear failures and the amount of longitudinal reinforcement selected to provide sufficient flexural capacity as calculated by the engineering beam theory. More recently, the strut-and-tie method has been used for the design of pile caps (disturbed or D-region) in which the load path is envisaged to be a three-dimensional truss, with compressive forces being supported by concrete compressive struts between the column and piles and tensile forces being carried by reinforcing steel located between piles. Both of these models have not provided uniform factors of safety against failure or been able to predict whether failure will occur by flexure (ductile mode) or shear (fragile mode). In this paper, an analytical model based on the strut-and-tie approach is presented. The proposed model has been calibrated using an extensive experimental database of pile caps subjected to compression and evaluated analytically for more complex loading conditions. It has been proven to be applicable across a broad range of test data and can predict the failures modes...

Economic design of (X)over-bar and R charts under Weibull shock models

Costa, AFB; Rahim, M. A.
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica Formato: 143-156
Português
Relevância na Pesquisa
37.1354%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); This paper considers the problem of a continuous production process where both the mean and variance are simultaneously monitored by an (X) over bar chart and R chart respectively, and generalizes the model of Costa (IIE Transactions 1993; 25(6):27-33). The product variable quality characteristic is assumed to be normally distributed and the process is subject to two independent assignable causes (such as tool wear-out, overheating or vibration). One cause changes the process mean and the other changes the process variance. However, the occurrence of one kind of assignable cause does not preclude the occurrence of the other. It is also assumed that the occurrence rimes of the assignable causes are described by Weibull distributions with increasing failure rates. A cost model is developed and a non-uniform sampling interval scheme is adopted. A two-step search procedure is employed to determine the optimal design parameters. The relative contribution of the paper over the results obtained by Costa is addressed. A sensitivity analysis of the model is conducted and the cost savings associated with the use of non-uniform sampling intervals instead of constant sampling intervals are evaluated. The economic design model is then extended to an economic-statistical design model for achieving desired levels of statistical performance while minimizing the expected cost. Performances of purely economic design and economic-statistical design are compared. Copyright (C) 2000 John Wiley & Sons...

Use of uniform designs in combination with neural networks for viral infection process development

Buenno, Laís Hara; Rocha, José Celso; Leme, Jaci; Caricati, Celso Pereira; Tonso, Aldo; Nuñez, Eutimio Gustavo Fernández
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 532-540
Português
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57.49306%
This work aimed to compare the predictive capacity of empirical models, based on the uniform design utilization combined to artificial neural networks with respect to classical factorial designs in bioprocess, using as example the rabies virus replication in BHK-21 cells. The viral infection process parameters under study were temperature (34°C, 37°C), multiplicity of infection (0.04, 0.07, 0.1), times of infection, and harvest (24, 48, 72 hours) and the monitored output parameter was viral production. A multilevel factorial experimental design was performed for the study of this system. Fractions of this experimental approach (18, 24, 30, 36 and 42 runs), defined according uniform designs, were used as alternative for modelling through artificial neural network and thereafter an output variable optimization was carried out by means of genetic algorithm methodology. Model prediction capacities for all uniform design approaches under study were better than that found for classical factorial design approach. It was demonstrated that uniform design in combination with artificial neural network could be an efficient experimental approach for modelling complex bioprocess like viral production. For the present study case, 67% of experimental resources were saved when compared to a classical factorial design approach. In the near future...

A hybrid model of uniform design and artificial neural network for the optimization of dietary metabolizable energy, digestible lysine, and methionine in quail chicks

Mehri,M; Ghazaghi,M
Fonte: Fundação APINCO de Ciência e Tecnologia Avícolas Publicador: Fundação APINCO de Ciência e Tecnologia Avícolas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2014 Português
Relevância na Pesquisa
67.098965%
A uniform design (UD) was used to construct models to explain the growth response of Japanese quails to dietary metabolizable energy (ME), and digestible methionine (dMet) and lysine (dLys) under tropical condition. In total, 100 floor pens with seven birds each were fed 25 UD different diets containing 25 ME (2808-3092 kcal/kg), dMet (0.31-0.49% of diet), and dLys (0.91-1.39% of diet) levels from 7 to 14 d of age. A platform of artificial neural network based on UD (ANN-UD) was generated to describe the growth response of the birds to dietary inputs using random search. Artificial neural networks of body weight gain (BWG) and feed conversion ratio (FCR) were optimized using random search algorithm. The optimization the ANN-UD results showed that maximum BWG may be achieved with 2995 kcal ME/kg, 0.45% dMet, and 1.18% dLys of diet; and minimum FCR may be obtained with 3000 kcal ME/kg, 0.45% dMet, and 1.17% dLys of diet. The result of this study showed that a ANN and UD hybrid model can be used successfully to optimize the nutritional requirements of quail chicks.

A model updating method for truss structure using stepwise uniform design schemes considered primary factors

Zhang,Shilei; Chen,Shaofeng; Wang,Huanding; Wang,Wei; Chen,Zaixian
Fonte: Associação Brasileira de Ciências Mecânicas Publicador: Associação Brasileira de Ciências Mecânicas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 Português
Relevância na Pesquisa
67.3698%
Based on the feasibility and reliability of a forward analytical model updating method with uniform design having been proven, this paper studies the effectiveness of the method in the condition that structural measured information is uncertain and incomplete. By taking the experimental data of a steel truss as an example, this paper studies the method of experimental data processing, the determination of structural model with unknown parameters, the interval estimation of identification results and stepwise uniform design considered the correlation among identification parameters. The results show that the errors between the numerical results computed by the updated model and the experimental data are acceptable, which means the method in this paper is feasible and reliable. In the end, based on our experiences and lessons, we summarize a model updating method for complex structures using stepwise uniform design schemes considered the primary and secondary factors, and expound its computational steps.

Performance-based design optimization using uniform deformation theory: a comparison study

Mohammadi,R. Karami; Ghasemof,A.
Fonte: Associação Brasileira de Ciências Mecânicas Publicador: Associação Brasileira de Ciências Mecânicas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2015 Português
Relevância na Pesquisa
37.211572%
The uniform deformation theory (UDT) is a relatively new concept in structural seismic design optimization. However, the results of optimization based on this theory have not yet been compared with other optimization techniques such as metaheuristics, and the optimality of the designs has been proved only by comparing the results with the conventional designs. This paper presents a new algorithm based on the UDT to performance-based design optimization (PBDO) of steel moment frames. In order to verify robustness of this method, the achieved results of PBDO for two baseline steel moment frames are compared with three metaheuristics consisting of genetic algorithm (GA), ant colony optimization (ACO), and particle swarm optimization (PSO). The results indicate that the optimization based on UDT provides a much higher convergence rate to the optimum design compared with metaheuristics.

Optimizing the Parameters of Vagus Nerve Stimulation by Uniform Design in Rats with Acute Myocardial Infarction

Kong, Shan-Shan; Liu, Jin-Jun; Hwang, Tyzh-Chang; Yu, Xiao-Jiang; Zhao, Mei; Zhao, Ming; Yuan, Bing-Xiang; Lu, Yi; Kang, Yu-Ming; Wang, Bing; Zang, Wei-Jin
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 26/11/2012 Português
Relevância na Pesquisa
46.83659%
Vagus nerve stimulation (VNS) has been shown to improve left ventricular function and survival in rats with acute myocardial infarction (AMI), and this maneuver has also been adopted clinically for the treatment of patients with chronic heart failure (CHF). Recent in vitro and in vivo studies have suggested that VNS can modulate the level of pro-inflammatory factors. Despite the beneficial effects of VNS, the stimulation parameters for obtaining favorable outcomes appear highly variable. To optimize VNS parameters, we set up different stimulation protocols with different pulse width (1–2 ms), frequency (1–6 Hz), voltage (1–6 V) and duration (40–240 min) of VNS by uniform design (UD). Rats were divided into seven groups with (Group1–Group6) or without VNS (MI group). Our results demonstrate that (1) the parameter sets in Group1, Group2 and Group3 yield the best post-MI protection by VNS, while the protective role were not observed in Group4, Group5 and Group6; (2) baroreflex sensitivity and the α7 nicotinic acetylcholine receptor level were also increased in Group1, Group2 and Group3. (3) the parameter set in Group1 (G1:1 ms, 2 Hz, 3 V, 240 min) is judged the most optimal parameter in this study as rats in this group not only showed a reduced myocardial injury with better-preserved cardiac function compared with other groups...

Preparation of ACE Inhibitory Peptides from Mytilus coruscus Hydrolysate Using Uniform Design

Wu, Jin-Chao; Cheng, Jie; Shi, Xiao-lai
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Português
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47.098965%
The angiotensin-I-converting enzyme (ACE) inhibitory peptides from mussel, Mytilus coruscus, were investigated and the variable factors, protease concentration, hydrolysis time, pH, and temperature, were optimized using Uniform Design, a new statistical experimental method. The results proved that the hydrolysate of alkali proteases had high ACE-inhibitory activity, especially the alkali protease E1. Optimization by Uniform Design showed that the best hydrolysis conditions for preparation of ACE-inhibitory peptides from Mytilus coruscus were protease concentration of 36.0 U/mL, hydrolysis time of 2.7 hours, pH 8.2, and Temperature at 59.5°C, respectively. The verification experiments under optimum conditions showed that the ACE-inhibitory activity (91.3%) were agreed closely with the predicted activity of 90.7%. The amino acid composition analysis of Mytilus coruscus ACE-inhibitory peptides proved that it had high percent of lysine, leucine, glycine, aspartic acid, and glutamic acid.

Attribute Index and Uniform Design Based Multiobjective Association Rule Mining with Evolutionary Algorithm

Zhang, Jie; Wang, Yuping; Feng, Junhong
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Publicado em 28/04/2013 Português
Relevância na Pesquisa
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In association rule mining, evaluating an association rule needs to repeatedly scan database to compare the whole database with the antecedent, consequent of a rule and the whole rule. In order to decrease the number of comparisons and time consuming, we present an attribute index strategy. It only needs to scan database once to create the attribute index of each attribute. Then all metrics values to evaluate an association rule do not need to scan database any further, but acquire data only by means of the attribute indices. The paper visualizes association rule mining as a multiobjective problem rather than a single objective one. In order to make the acquired solutions scatter uniformly toward the Pareto frontier in the objective space, elitism policy and uniform design are introduced. The paper presents the algorithm of attribute index and uniform design based multiobjective association rule mining with evolutionary algorithm, abbreviated as IUARMMEA. It does not require the user-specified minimum support and minimum confidence anymore, but uses a simple attribute index. It uses a well-designed real encoding so as to extend its application scope. Experiments performed on several databases demonstrate that the proposed algorithm has excellent performance...

Combination of uniform design with artificial neural network coupling genetic algorithm: an effective way to obtain high yield of biomass and algicidal compound of a novel HABs control actinomycete

Cai, Guanjing; Zheng, Wei; Yang, Xujun; Zhang, Bangzhou; Zheng, Tianling
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Publicado em 24/05/2014 Português
Relevância na Pesquisa
46.83659%
Controlling harmful algae blooms (HABs) using microbial algicides is cheap, efficient and environmental-friendly. However, obtaining high yield of algicidal microbes to meet the need of field test is still a big challenge since qualitative and quantitative analysis of algicidal compounds is difficult. In this study, we developed a protocol to increase the yield of both biomass and algicidal compound present in a novel algicidal actinomycete Streptomyces alboflavus RPS, which kills Phaeocystis globosa. To overcome the problem in algicidal compound quantification, we chose algicidal ratio as the index and used artificial neural network to fit the data, which was appropriate for this nonlinear situation. In this protocol, we firstly determined five main influencing factors through single factor experiments and generated the multifactorial experimental groups with a U15(155) uniform-design-table. Then, we used the traditional quadratic polynomial stepwise regression model and an accurate, fully optimized BP-neural network to simulate the fermentation. Optimized with genetic algorithm and verified using experiments, we successfully increased the algicidal ratio of the fermentation broth by 16.90% and the dry mycelial weight by 69.27%. These results suggested that this newly developed approach is a viable and easy way to optimize the fermentation conditions for algicidal microorganisms.

Constructal design of non-uniform x-shaped cavity

Link, Fernanda Bichet; Santos, Elizaldo Domingues dos; Isoldi, Liércio André; Rocha, Luiz Alberto de Oliveira
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Conferência ou Objeto de Conferência
Português
Relevância na Pesquisa
37.098965%
This paper applies constructal design to study a non-uniform X-shaped cavity that penetrates a conductive solid wall. The goal is to minimize the maximal dimensionless excess of temperature between the solid body and cavity. There is a uniform heat generation on the solid body. The total volume and the volume of the cavity are fixed, but the angle formed between the stems of the cavity may vary. The cavity surfaces are isothermal while the solid body has adiabatic conditions in the outer surface. Results indicate that the optimal X-cavity performs 60.1% better than the Cshaped cavity and 44% better than the T-shaped cavity. However, it has a performance approximately 38% inferior than the performance of the optimized H-shaped cavity.

RISK-BASED DESIGN OF BRIDGES AND ASSOCIATED TRANSPORTATION NETWORKS UNDER NATURAL HAZARDS

Wang, Zhenghua
Fonte: Universidade Rice Publicador: Universidade Rice
Português
Relevância na Pesquisa
37.486414%
The highway infrastructure system in the United States is deteriorating and facing an increased number of threats from natural and man-made hazards, including earthquakes, scour, hurricanes, and vehicle collisions. At the same time, the reliable functioning of the highway system plays an important role in emergency response and recovery processes after disaster strikes. However, there are several inadequacies in current codes and associated practice for the design of bridges, as well as funding restrictions for their upkeep. Although recent changes in the seismic design of bridges have adopted displacement-based design approaches to promote adequate performance under seismic loads, the current design philosophy hinges upon a uniform hazard perspective without explicit consideration of a homogeneous risk of damage or collapse. In addition, this approach does not reflect the influence of individual bridges on the transportation network behaviour, which is desirable to estimate the performance of a transportation infrastructure system and enhance its overall post-event operation. Moreover, current bridge design specifications deal with various extreme hazards independent of one another. The reliable performance of transportation infrastructure systems under natural hazards requires a new life-cycle risk-based design method...

Investment incentives and auction design in electricity markets

Fabra, Natalia; Fehr, Nils-Henrik M von der; Frutos, María Ángeles de
Fonte: Centre for Economic Policy Research Publicador: Centre for Economic Policy Research
Tipo: Trabalho em Andamento Formato: application/pdf
Publicado em /01/2008 Português
Relevância na Pesquisa
37.166096%
Motivated by the regulatory debate in electricity markets, we seek to understand how market design affects market performance through its impact on investment incentives. For this purpose, we study a two-stage game in which firms choose their capacities under demand uncertainty prior to bidding into the spot market. We analyse a number of different market design elements, including (i) two commonly used auction formats, the uniform-price and discriminatory auctions, (ii) price-caps and (iii) bid duration. We find that, although the discriminatory auction tends to lower prices, this does not imply that investment incentives at the margin are poorer; indeed, under reasonable assumptions on the shape of the demand distribution, the discriminatory auction induces (weakly) stronger investment incentives than the uniform-price format.

Pack Level Design Optimization for Electric Vehicle Thermal Management Systems Minimizing Standard Deviation of Temperature Distribution

Bakker, Jeremy
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
37.151023%
Green technologies have recently gained interest for many reasons. Economic factors in conjunction with an increased social desire to reduce our environmental impact on the Earth have created a desire for more environmentally friendly technologies, especially automotive technologies such as the electric car. While public interest in electric vehicles is growing, there are a number of challenges which must first be addressed before their widespread adoption is possible. Cost, longevity, and range are all important factors which need to be addressed for electric vehicles to compete directly with their gasoline counterparts. By more efficiently using the energy stored within the battery pack, some of these issues can be addressed. This study focuses on the thermal management systems for electric vehicles and the application of design optimization in the early design phase considering the pack in its entirety. A liquid cooling system is considered for a current generation electric vehicle, with time dependent heat generation rates within the battery cells based on vehicle operating conditions. Identifying the most efficient distribution of cooling within the battery pack to achieve uniform temperature is the objective of optimization. Simulations were performed on a complete battery pack model...

A first attempt towards reliability-based calibration of Brazilian structural design codes

BECK, André Teófilo; SOUZA JR., Antônio C. de
Fonte: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM Publicador: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM
Tipo: Relatório
Português
Relevância na Pesquisa
37.1354%
This paper addresses the reliability-based calibration of partial safety factors for Brazilian design codes NBR8681:2003 (Actions and Safety of Structures) and NBR8800:2008 (Design of Steel and Steel-Concrete Composite Structures). To the author's knowledge, these codes have never been subject to reliability-based calibration of partial and load combination factors. This paper represents a first effort in reaching this goal. The present calibration effort is based on actual data for wind loads in south east of Brazil, but uses mainly international data for other problem parameters. So far, the investigation is limited to structural steel members. The investigation leads to a set of optimized partial safety factors, which are compared to partial factors currently used in Brazilian design codes. Results show that the optimized set of partial factors leads to more uniform reliability for different design situations and load combinations. The investigation includes an analysis of the economical impact of replacing the current set of partial factors by the calibrated factors found in this paper. It is shown that, with an optimized set of partial safety factors, it is possible to maintain the current level of reliability and still produce a 5% average reduction in expenditure with structural materials...

A first attempt towards reliability-based calibration of Brazilian structural design codes

Beck,André Teófilo; Souza Jr.,Antônio C. de
Fonte: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM Publicador: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2010 Português
Relevância na Pesquisa
37.1354%
This paper addresses the reliability-based calibration of partial safety factors for Brazilian design codes NBR8681:2003 (Actions and Safety of Structures) and NBR8800:2008 (Design of Steel and Steel-Concrete Composite Structures). To the author's knowledge, these codes have never been subject to reliability-based calibration of partial and load combination factors. This paper represents a first effort in reaching this goal. The present calibration effort is based on actual data for wind loads in south east of Brazil, but uses mainly international data for other problem parameters. So far, the investigation is limited to structural steel members. The investigation leads to a set of optimized partial safety factors, which are compared to partial factors currently used in Brazilian design codes. Results show that the optimized set of partial factors leads to more uniform reliability for different design situations and load combinations. The investigation includes an analysis of the economical impact of replacing the current set of partial factors by the calibrated factors found in this paper. It is shown that, with an optimized set of partial safety factors, it is possible to maintain the current level of reliability and still produce a 5% average reduction in expenditure with structural materials...

Validação de design de armazém automatizado com uso de simulação discreta; Validation of automated warehouse design with use of discrete simulation

Peixoto, Robson Teles
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Dissertação de Mestrado
Publicado em //2015 Português
Relevância na Pesquisa
37.091133%
Dissertação de mestrado em Engenharia de Sistemas; O objetivo da investigação é realizar a validação do processo de conceção de um armazém automatizado por meio da construção de modelos de simulação, nos softwares ARENA e SIMIO, que representem as alternativas planeadas.A investigação foi baseada no método de estudo de caso e foi realizada conforme informações fornecidas pela Subdiretoria de Abastecimento, órgão responsável pela rede de distribuição de fardamento aos militares e material de apoio às organizações do Comando da Aeronáutica do Brasil. As perguntas de investigação visam identificar se a inclusão de um subsistema de separação automatizado para composição dos kitsindividuais de fardamento no armazém central atende aos novos requisitos da cadeia de abastecimento e se a inclusão do novo processoviabiliza a movimentação dos demais produtos durante o horário preestabelecido.A investigação concluiu que é possível realizar a separação dos kits em simultâneo com a separação dos produtos de apoio, em conformidade com os requisitos apresentados. No entanto, torna-se necessário a implantação de regras de sequenciamento das retiradas, a implantação do método de armazenamento por classes...

Estimates for the pressure and thermal distortions of coating dies for use in design and simulation

Shetty, Sneha
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
37.091133%
A coating die is used for distributing liquid in order to apply a uniform film on a solid surface. The fluid flowing through the die cavity can exert a pressure of up to 500,000 Pascal on the die body. This liquid pressure can distort the die and lead to a non-uniform slot opening, which in turn causes non-uniformity in the coating thickness. Distortion of the die can also occur during non-isothermal operation of the die; this is an undesired consequence of delivering liquids at a different temperature than the die itself. The distortions undergone by the die both due to liquid pressure and non-isothermal conditions should be within the manufacturing tolerances for the slot heights in order to maintain uniformity in the coating. The deformation exhibited by a coating die due to pressure loadings is modeled both two-dimensionally and three-dimensionally. A two-dimensional model has lower computational load and is preferred for die design. For the two-dimensional analysis of a coating die, the finite element method is used to determine the deflections due to pressure loadings with a focus on slot heights. A model of low computational load is also developed based on beam theory, and its results are compared with those of the two-dimensional finite element analyses predictions. The beam model is incorporated in a die design and simulation program in which flow and slot deformations are coupled. Two-dimensional finite element analyses due to non-isothermal conditions are also performed on the coating die to give an estimate of the die deflection due to temperature variations within the die. A three-dimensional coating die with varying inner cavity area is modeled and analyzed to check its predictions with those of the two-dimensional finite element analyses and beam theory results. In the literature reviewed...

Optimal synthesis of a Ni(II)-dimethylglyoxime ion-imprinted polymer for the enrichment of Ni(II) ions in water, soil and mine tailing samples

Rammika,Modise; Darko,Godfred; Torto,Nelson
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 Português
Relevância na Pesquisa
47.098965%
A Ni(II)-dimethylglyoxime ion-imprinted polymer {Ni(II)-DMG IIP} was optimised by the uniform design experimental method and used to adsorb Ni(II) ions from water, soil and mine tailing samples. This aimed to improve the performance of this ion-imprinted polymer in trapping Ni(II) ions from soil and mine tailing samples which are characterised by complex matrices. The optimisation was carried out by varying the molar ratios of monomer to crosslinker to porogen and template to ligands, as well as by keeping these parameters constant and varying the concentrations of initiator, 2,2'-azobisisobu-tyronitrile (AIBN). The optimal molar ratios of crosslinker to monomer, monomer to template and nickel(II) sulphate hexahydrate (NiSO4.6H2O) to 4-vinylpyridine to dimethylglyoxime were found to be 3.3:1.0, 0.6:1.0 and 1.0:0.6:3.6, respectively, with 30 mg and 8 mℓ as the optimum amounts of initiator and porogen, respectively. Through this optimisation, extraction efficiency for Ni(II) increased from 98 to 100% in aqueous samples. The extraction efficiencies for the soil and mine tailing samples were 98-99% and 99%, respectively, with an enrichment factor of 2 in mine tailing samples and ranging from 27 to 40 in soil samples. The method displayed good accuracy...