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Selected AbstractsWelding and Marking of Plastics with LasersLASER TECHNIK JOURNAL, Issue 5 2010New absorbers increase possibilities for application Today laser radiation as a tool for The Authors welding, cutting and marking in manufacturing of plastic components and products has achieved a good market acceptance. It offers an alternative to conventional processes such as ultrasonic, vibration or friction welding, mechanical cutting, milling or water jet cutting, tampon printing or ink jet printing. Main advantages for laser marking are flexibility and a contact free process [1]. Laser welding of plastics offers advantages in case of cleanness of processed components, low thermal and mechanical stress to components and inner sensitive parts as well as flexibility [2]. Although laser beam welding seems to be a relatively expensive processing method, savings can be achieved by entirely consideration of production process and logistics. [source] Seismic isolation of buildings with sliding concave foundation (SCF)EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 1 2003M. Hamidi Abstract In this paper, a new base isolation system, namely the sliding concave foundation (SCF), is introduced and the behaviour of the buildings using such a system is theoretically investigated. A building supported on the new system behaves like a compound pendulum during seismic excitation. The pendulum behaviour accompanied by the large radius of foundation curvature shifts the fundamental period of the system to a high value (e.g. more than 8sec), in a frequency range where none of the previously recorded earthquakes had considerable energy. This results in a large decrease in the structural responses. Since small friction forces are essential on the contact surfaces, PTFE sheets can be used as sliding surfaces. Although the pure frictional sliding systems have the same efficiency as the SCF, in reducing the responses of the superstructure, the main advantage of the new system is a significant decrease in sliding displacement. The performance of the SCF subjected to a number of harmonic and non-harmonic base excitations is studied and its ability to reduce the structural responses is examined. Some numerical examples are solved for a single-degree-of-freedom (SDOF) structure and the responses are compared with the responses of the same SDOF structure on a fixed base or a pure frictional sliding support system. The comparisons confirm the effectiveness of the new system. Copyright © 2002 John Wiley & Sons, Ltd. [source] Magnebike: A magnetic wheeled robot with high mobility for inspecting complex-shaped structuresJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 5 2009Fabien Tâche This paper describes the Magnebike robot, a compact robot with two magnetic wheels in a motorbike arrangement, which is intended for inspecting the inner casing of ferromagnetic pipes with complex-shaped structures. The locomotion concept is based on an adapted magnetic wheel unit integrating two lateral lever arms. These arms allow for slight lifting off the wheel in order to locally decrease the magnetic attraction force when passing concave edges, as well as laterally stabilizing the wheel unit. The robot has the main advantage of being compact (180 × 130 × 220 mm) and mechanically simple: it features only five active degrees of freedom (two driven wheels each equipped with an active lifter stabilizer and one steering unit). The paper presents in detail design and implementation issues that are specific to magnetic wheeled robots. Low-level control functionalities are addressed because they are necessary to control the active system. The paper also focuses on characterizing and analyzing the implemented robot. The high mobility is shown through experimental results: the robot not only can climb vertical walls and follow circumferential paths inside pipe structures but it is also able to pass complex combinations of 90-deg convex and concave ferromagnetic obstacles with almost any inclination regarding gravity. It requires only limited space to maneuver because turning on the spot around the rear wheel is possible. This high mobility enables the robot to access any location in the specified environment. Finally the paper analyzes the maximum payload for different types of environment complexities because this is a key feature for climbing robots and provides a security factor about the risk of falling and slipping. © 2009 Wiley Periodicals, Inc. [source] Multivariate monitoring of batch processes using batch-to-batch informationAICHE JOURNAL, Issue 6 2004Jesus Flores-Cerrillo Abstract Multiway principal component analysis (MPCA) and multiway partial-least squares (MPLS) are well-established methods for the analysis of historical data from batch processes, and for monitoring the progress of new batches. Direct measurements made on prior batches can also be incorporated into the analysis by monitoring with multiblock methods. An extension of the multiblock MPCA/MPLS approach is introduced to explicitly incorporate batch-to-batch trajectory information summarized by the scores of previous batches, while keeping all the advantages and monitoring statistics of the traditional MPCA/MPLS. However, it is shown that the advantages of using information on prior batches for analysis and monitoring are often small. Its main advantage is that it can be useful for detecting problems when monitoring new batches in the early stages of their operation., the approach and benefits are illustrated with condensation polymerization and emulsion polymerization systems, as examples. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1219,1228, 2004 [source] Linearized transport model for nanofiltration: Development and assessmentAICHE JOURNAL, Issue 4 2002W. Richard Bowen Finite difference linearization of pore concentration gradient in nanofiltration membranes greatly simplifies the solution of a three-parameter model (pore radius, membrane charge, and pore dielectric constant) for electrolyte rejection by removing the requirement for numerical integration of the extended Nernst,Planck equation. The validity of the linearized model is first experimentally tested by comparing with a rigorous characterization of the Desal-DK nanofiltration membrane, the linearized model closely agreeing with the numerical solution of the full model. Investigation of pore concentration profiles showed the assumption of linearity to be valid over a wide range of nanofiltration conditions. The linearized model was also successfully extended to ternary electrolyte mixtures, highlighting its main advantage over analytic solutions. Overall, the model is a powerful tool for characterization of nanofiltration membranes and subsequent prediction of separation performance. Computational demands are modest in terms of time and complexity. [source] Quick prediction of the retention of solutes in 13 thin layer chromatographic screening systems on silica gel by classification and regression treesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 15 2008ukasz Komsta Abstract The use of classification and regression trees (CART) was studied in a quantitative structure,retention relationship (QSRR) context to predict the retention in 13 thin layer chromatographic screening systems on a silica gel, where large datasets of interlaboratory determined retention are available. The response (dependent variable) was the rate mobility (RM) factor, while a set of atomic contributions and functional substituent counts was used as an explanatory dataset. The trees were investigated against optimal complexity (number of the leaves) by external validation and internal crossvalidation. Their predictive performance is slightly lower than full atomic contribution model, but the main advantage is the simplicity. The retention prediction with the proposed trees can be done without computer or even pocket calculator. [source] Bootstrap predictive inference for ARIMA processesJOURNAL OF TIME SERIES ANALYSIS, Issue 4 2004Lorenzo Pascual Abstract., In this study, we propose a new bootstrap strategy to obtain prediction intervals for autoregressive integrated moving-average processes. Its main advantage over other bootstrap methods previously proposed for autoregressive integrated processes is that variability due to parameter estimation can be incorporated into prediction intervals without requiring the backward representation of the process. Consequently, the procedure is very flexible and can be extended to processes even if their backward representation is not available. Furthermore, its implementation is very simple. The asymptotic properties of the bootstrap prediction densities are obtained. Extensive finite-sample Monte Carlo experiments are carried out to compare the performance of the proposed strategy vs. alternative procedures. The behaviour of our proposal equals or outperforms the alternatives in most of the cases. Furthermore, our bootstrap strategy is also applied for the first time to obtain the prediction density of processes with moving-average components. [source] Labour Market in Motion: Analysing Regional Flows in a Multi-accounting SystemLABOUR, Issue 4-5 2007Anette Haas We develop a flexible flow approach system , a multi-accounting system (MAS) , dealing with flows and stocks on regional labour markets. Combining administrative data at the micro level with various macro data, the MAS describes the dynamic transition process of the 180 local labour market areas in Germany. We use a new algorithm, related to entropy optimization, to estimate unknown transitions. Compared with conventional methods, the main advantage of our proceeding is that additional information from different data sources can be included that is of an inherently fuzzy character. [source] Atypical antipsychotic drugs and diabetesPRACTICAL DIABETES INTERNATIONAL (INCORPORATING CARDIABETES), Issue 9 2003Dr C Livingstone BSc, MBChB, MRCPath Consultant Chemical Pathologist Abstract The atypical antipsychotic drugs have enhanced the quality of life in many patients with schizophrenia. Their main advantage over conventional antipsychotic drugs is their propensity to cause fewer extrapyramidal adverse effects. However, there is increasing evidence that atypical antipsychotic drugs are associated with metabolic adverse effects including weight gain, new onset diabetes (both type 2 diabetes and diabetic ketoacidosis) and hypertriglyceridaemia. These problems are most common with clozapine. We discuss the mechanism of the association and recommendations for screening and monitoring in order that metabolic problems can be detected and treated early. Copyright © 2003 John Wiley & Sons, Ltd. [source] HP10 LAPAROSCOPIC RESECTION OF SUBMUCOSAL GASTRIC LESIONS , THE WHANGAREI EXPERIENCEANZ JOURNAL OF SURGERY, Issue 2007J. Y. Yang Purpose To evaluate safety of laparoscopic resection of submucosal gastric lesions performed in Whangarei Based Hospital. Methodology From November 2002 to December 2006, 8 consecutive patients underwent the above mention surgery. (M : F = 5 : 3; Average age 63 [range, 43,83]). All patients underwent pre-operative gastroscopy. Wedge resections were performed for anterior wall lesions. (n = 3). Posterior wall lesions were resected via transgastric approach. (n = 4). Retroperitoneal resection was performed for the foregut duplication cyst. (n = 1). All except one lesion were resected using endoscopic GIA stapler. The medical records of the patients were reviewed retrospectively. Results All patients were successfully treated laparoscopically. No conversion to open surgery. Pathology included: Gastrointestinal-stromal tumor (GIST) (n = 5), Malignant leiomyosarcoma (n = 1), Ectopic pancreas (n = 1), and Foregut duplication cysts (n = 1). All achieved adequate negative surgical margin. Average operation time was 106.14 minutes. [Range, 75,150]. Average length of hospital stay was 3.42 days [range, 1,5]. Complication included one wound infection, and one pyloric stenosis. Average length of follow up was 10.96 months [range, 0.46,31.73]. No recurrence detected and all are still alive till date. Conclusion Laparoscopic resection of submucosal gastric lesions is a safe and appropriate alternative to open surgery. Its main advantage over open technique includes shorter length of hospital stay, lower recurrence rate and lower mortality rates. Surgical technique depends very much on tumor size and location. Outcome of the patients described from our centre is comparable to the others published till date. [source] Nonlinear parametric predictive control.ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2009Application to a continuous stirred tank reactor Abstract This paper presents a nonlinear model-based controller based on the ideas of parametric predictive control applied to a continuous stirred tank reactor (CSTR) process unit. Controller design aims at avoiding the complexity of implementation and long computational times associated with conventional NMPC while maintaining the main advantage of taking into account process nonlinearities that are relevant for control. The design of the parametric predictive controller is based on a rather simplified process model having parameters that are instrumental in determining the required changes to the manipulated variables for error reduction. The nonlinear controller is easy to tune and can operate successfully over a wide range of operating conditions. The use of an estimator of unmeasured disturbances and process-model mismatch further enhances the behavior of the controller. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Realistic and efficient rendering of free-form knitwearCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 1 2001Hua Zhong Abstract We present a method for rendering knitwear on free-form surfaces. This method has three main advantages. First, it renders yarn microstructure realistically and efficiently. Second, the rendering efficiency of yarn microstructure does not come at the price of ignoring the interactions between the neighboring yarn loops. Such interactions are modeled in our system to further enhance realism. Finally, our approach gives the user intuitive control on a few key aspects of knitwear appearance: the fluffiness of the yarn and the irregularity in the positioning of the yarn loops. The result is a system that efficiently produces highly realistic rendering of free-form knitwear with user control on key aspects of visual appearance. Copyright © 2001 John Wiley & Sons, Ltd. [source] Integrating physiological, ecological and evolutionary change: a Price equation approachECOLOGY LETTERS, Issue 8 2009Sinéad Collins Abstract We use a general quantitative framework , the Price equation , to partition phenotypic responses to environmental change into separate physiological, evolutionary and ecological components. We demonstrate how these responses, which potentially occur over different timescales and are usually studied in isolation, can be combined in an additive way; and we discuss the main advantages of doing this. We illustrate our approach using two worked examples, concerning the emergence of toxin resistance within microbial communities, and the estimation of carbon uptake by marine phytoplankton in high-CO2 environments. We find that this approach allows us to exclude particular mechanistic hypotheses with regard to community-level transformations, and to identify specific instances where appropriate data are lacking. Thus Price's equation provides not only a powerful conceptual aid, but also a means for testing hypotheses and for directing empirical research programmes. [source] Optimization of capillary electrophoretic enantioseparation for basic drugs with native ,-CD as a chiral selectorELECTROPHORESIS, Issue 12 2006Nerissa L. Deñola Abstract This study presents the advantages of the 20,µm inner diameter (id) capillary for the enantioseparation of ten basic drugs with native ,-CD as the chiral selector. The apparent binding constants of each enantiomeric pair were determined to calculate the optimum ,-CD concentration ([,-CD]opt) and the optimization was subsequently carried out. Comparison of the 20,µm id with 50,µm id were made in terms of the results obtained in the optimization and detection limits. Applying the optimum conditions for each compound, reproducible results (RSD from 0,3; n>5) were obtained for the 20,µm id capillary. Although the sensitivity is lower in the 20,µm id capillary, the LOD determined using this capillary is still found to be acceptable for the ten basic drugs studied. Enhanced resolution and faster analysis times were the main advantages observed with the use of this capillary in enantioseparation. [source] Online expert systems for fault diagnosis in technical processesEXPERT SYSTEMS, Issue 2 2008Chrissanthi Angeli Abstract: It is generally accepted that there has been an increasing interest in online fault detection and diagnosis techniques for technical processes during the last few years. These techniques come from the artificial intelligence field or are classical numerical methods in combination with artificial intelligence methods. This paper presents a survey of recent research work in online expert systems for fault detection and diagnosis in technical processes. In addition, a short reference to other recent artificial intelligence methods for online fault detection is included and the main advantages and limitations of each method are illustrated. [source] Spectral-element simulations of global seismic wave propagation,II.GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2002Three-dimensional models, oceans, rotation, self-gravitation Summary We simulate global seismic wave propagation based upon a spectral-element method. We include the full complexity of 3-D Earth models, i.e. lateral variations in compressional-wave velocity, shear-wave velocity and density, a 3-D crustal model, ellipticity, as well as topography and bathymetry. We also include the effects of the oceans, rotation and self-gravitation in the context of the Cowling approximation. For the oceans we introduce a formulation based upon an equivalent load in which the oceans do not need to be meshed explicitly. Some of these effects, which are often considered negligible in global seismology, can in fact play a significant role for certain source,receiver configurations. Anisotropy and attenuation, which were introduced and validated in a previous paper, are also incorporated in this study. The complex phenomena that are taken into account are introduced in such a way that we preserve the main advantages of the spectral-element method, which are an exactly diagonal mass matrix and very high computational efficiency on parallel computers. For self-gravitation and the oceans we benchmark spectral-element synthetic seismograms against normal-mode synthetics for the spherically symmetric reference model PREM. The two methods are in excellent agreement for all body- and surface-wave arrivals with periods greater than about 20 s in the case of self-gravitation and 25 s in the case of the oceans. At long periods the effect of gravity on multiorbit surface waves up to R4 is correctly reproduced. We subsequently present results of simulations for two real earthquakes in fully 3-D Earth models for which the fit to the data is significantly improved compared with classical normal-mode calculations based upon PREM. For example, we show that for trans-Pacific paths the Rayleigh wave can arrive more than a minute earlier than in PREM, and that the Love wave is much shorter in duration. [source] Electromagnetic fields in a steel-cased boreholeGEOPHYSICAL PROSPECTING, Issue 1 2005Ki Ha Lee ABSTRACT The development of an electromagnetic numerical modelling scheme for a magnetic dipole in an arbitrary casing segment in an inhomogeneous conductivity background has been difficult, due to the very high electrical conductivity and magnetic permeability contrasts between the steel casing and the background medium. To investigate the effect of steel casing efficiently, we have developed an accurate but simple finite-element modelling scheme to simulate electromagnetic fields in a medium of cylindrically symmetric conductivity structures. In order to preserve the cylindrical symmetry in the resulting electromagnetic fields, a horizontal loop current source is used throughout. One of the main advantages of the approach is that the problem is scalar when formulated using the azimuthal electric field, even if the casing is both electrically conductive and magnetically permeable. Field calculations have been made inside the cased borehole as well as in another borehole which is not cased. Careful analyses of the numerical modelling results indicate that the anomaly observed in a cross-borehole configuration is sensitive enough to be used for tomographic imaging. [source] The interaction between corporate rescue and labour legislation: lessons to be drawn from the South African experienceINTERNATIONAL INSOLVENCY REVIEW, Issue 1 2005Anneli Loubser One of the main advantages of a successful corporate rescue is that it prevents or at least limits the job losses caused by a business failure. For this reason, labour legislation which is designed to protect the employees of a company in the event of its winding-up, should take cognisance of the effects such legislation may have on any rescue attempts. As the recent experience in South Africa has shown, ignoring corporate rescue in legislation dealing with labour law in the context of the winding-up of a company may have the unintended effect of seriously hampering any corporate rescue attempt. Copyright © 2004 John Wiley & Sons, Ltd. [source] Integration schemes for von-Mises plasticity models based on exponential maps: numerical investigations and theoretical considerationsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 9 2005E. Artioli Abstract We consider three different exponential map algorithms for associative von-Mises plasticity with linear isotropic and kinematic hardening. The first scheme is based on a different formulation of the time continuous plasticity model, which automatically grants the yield consistency of the method in the numerical solution. The second one is the quadratically accurate but non-yield consistent method already proposed in Auricchio and Beirão da Veiga (Int. J. Numer. Meth. Engng 2003; 56: 1375,1396). The third method is an improved version of the second one, in which the yield consistency condition is enforced a posteriori. We also compare the performance of the three methods with the classical radial return map algorithm. We develop extensive numerical tests which clearly show the main advantages and disadvantages of the three methods. Copyright © 2005 John Wiley & Sons, Ltd. [source] Towards analog implementations of PWL two-dimensional non-linear functionsINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 2 2005Marco Storace Abstract This paper deals with the circuit implementation of non-linear algebraic bivariate functions. The synthesis procedure is based on a piecewise-linear approximation technique and on a corresponding circuit architecture, whose basic element is a circuit block with the input/output function y(x) = max(0; x). Some known CMOS circuit structures that can be used to obtain such a block are considered, and their main advantages and drawbacks are pointed out. The static and dynamic features of both the single circuit block and the overall architecture for two-dimensional PWL functions are illustrated by way of examples. Copyright © 2005 John Wiley & Sons, Ltd. [source] The economic value of technical trading rules: a nonparametric utility-based approachINTERNATIONAL JOURNAL OF FINANCE & ECONOMICS, Issue 1 2005Hans Dewachter Abstract We adapt Brandt's (1999) nonparametric approach to determine the optimal portfolio choice of a risk averse foreign exchange investor who uses moving average trading signals as the information instrument for investment opportunities. Additionally, we assess the economic value of the estimated optimal trading rules based on the investor's preferences. The approach consists of a conditional generalized method of moments (GMM) applied to the conditional Euler optimality conditions. The method presents two main advantages: (i) it avoids ad hoc specifications of statistical models used to explain return predictability; and (ii) it implicitly incorporates all return moments in the investor's expected utility maximization problem. We apply the procedure to different moving average trading rules for the German mark,US dollar exchange rate for the period 1973,2001. We find that technical trading rules are partially recovered and that the estimated optimal trading rules represent a significant economic value for the investor. Copyright © 2005 John Wiley & Sons, Ltd. [source] Wavelet analysis applied to removing non-constant, varying spectroscopic background in multivariate calibrationJOURNAL OF CHEMOMETRICS, Issue 5 2002Hu-Wei Tan Abstract Multiresolution, the ability to separate signals according to frequency, is one of the main advantages offered by the wavelet transform. However, the coarsening of resolution associated with this method may be problematic in some applications. The ,wavelet prism' (WP) method proposed here can split the signal into different frequency components, which retain the original resolution of the signal. In conjunction with a maximum information gain criterion developed here, this new method can be used to judge and remove the low-frequency non-constant background variation reasonably and automatically. In this paper the theory and background concerning this wavelet baseline correction method are introduced. The method is successfully applied to simulated and real near-infrared (NIR) spectral data to deal with non-constant background for multivariate calibration. Its performance compares favorably with the current signal correction methods for background removal. The new method appears to be an efficient method for removal of non-constant, varying spectroscopic background, leading to a simpler and more parsimonious multivariate linear model. Copyright © 2002 John Wiley & Sons, Ltd. [source] Economic Efficiency and Frontier TechniquesJOURNAL OF ECONOMIC SURVEYS, Issue 1 2004Luis R. Murillo-Zamorano Abstract. Most of the literature related to the measurement of economic efficiency has based its analysis either on parametric or on non-parametric frontier methods. The choice of estimation method has been an issue of debate, with some researchers preferring the parametric and others the non-parametric approach. The aim of this paper is to provide a critical and detailed review of both core frontier methods. In our opinion, no approach is strictly preferable to any other. Moreover, a careful consideration of their main advantages and disadvantages, of the data set utilized, and of the intrinsic characteristics of the framework under analysis will help us in the correct implementation of these techniques. Recent developments in frontier techniques and economic efficiency measurement such as Bayesian techniques, bootstrapping, duality theory and the analysis of sampling asymptotic properties are also considered in this paper. [source] Accuracy of orientation distribution function determination based on EBSD data-A case study of a recrystallized low alloyed Zr sheetJOURNAL OF MICROSCOPY, Issue 3 2007N. BOZZOLO Summary The question of the statistical accuracy of EBSD data for global texture calculation was re-explored on the basis of a very large grain population (83 000 grains measured on a recrystallized low-alloyed Zr sheet). Previous works aimed mainly at identifying and quantifying the main texture components and were based on much smaller data sets. The present work attempts to quantify the accuracy of the complete texture, including low-density regions of the orientation space. For that purpose, a new statistical parameter, V,, based on the calculation of texture difference functions is proposed. This parameter has two main advantages: it is equally sensitive to both high and low peaks of the orientation density function (ODF), and it has a physical interpretation because it is the material volume fraction corresponding to the difference between a given ODF and a reference ODF (considered, or known to be close to the truth). Two main variables were studied: the number of grains taken into account and the peak width ,0 of Bunge's ,Gaussian' model density used as kernel for the actual analysis. The orientation distribution functions were computed by nonparametric kernel density estimation with harmonics up to the order of 34. Minimizing the value of V, serves as the objective function for optimizing the peak width ,0 as a function of the number of grains. The properties of the V, parameter also allows for the definition of a method for estimating the accuracy of a given texture that has been obtained from a limited number of grains, without knowing the true texture of the investigated material. [source] Novel experiments and a mechanistic model for macroinstabilities in stirred tanksAICHE JOURNAL, Issue 2 2006A. Paglianti Abstract In this work a new experimental technique and a simple model for the identification and the analysis of macro-instabilities (MIs) in stirred tanks are presented. A pressure transducer is proposed for detecting the MIs that can take place inside a stirred vessel; its main advantages are the non-intrusivity, cheapness, and simplicity of installation and operation. Moreover, it can be used for both laboratory and industrial scale stirred tanks. The experimental technique and the time series analysis method, based on Fast Fourier Transform (FFT), are shown to provide reliable information on the frequency of MIs, through the comparison of the present data with those, from literature, obtained in similar systems. Its applicability to solid-liquid systems is also assessed. Afterwards, the data collected in several conditions differing by geometric characteristics of the stirred tanks and by the physical properties of the systems are presented. Finally, a new simplified model, based on the theory of impinging jets,1 is suggested for predicting the MI frequency. © 2005 American Institute of Chemical Engineers AIChE J, 2006 [source] Application of solid phase microextraction for the determination of soil fumigants in water and soil samplesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 1 2005Sonia Fuster Abstract The potential of solid phase microextraction (SPME) for the determination of the soil fumigants 1,3-dichloropropene (1,3-DCP) and methyl isothiocyanate (MITC) in environmental samples such as soil and water samples has been investigated. Direct immersion SPME followed by GC/ECD/NPD analysis allowed the rapid determination of the two fumigants in water samples, with very little sample manipulation, giving an LOD of 0.5 ,g L,1. Precision, calculated as relative standard deviation (RSD) for six replicates at three concentration levels, was found to be lower than 20% at the concentration levels tested. For the analysis of soil samples, headspace (HS)-SPME combined with GC/ECD/NPD analysis has been applied. Quantification using matrix-matched calibration curves allowed determination of both analytes (MITC and 1-3-DCP) with a LOD of 0.1 ,g kg,1 (RSD <10%) for the two concentration levels assayed (0.02 and 0.2 mg kg,1). The HS-SPME procedure developed in this paper was applied to soil samples from experimental green house plots treated with metham-Na, a soil disinfestation agent that decomposes in soil to MITC. The absence of sample manipulation as well as the low solvent consumption in SPME methodology are among the main advantages of this analytical approach. [source] Centrifugal Gel Casting: A Combined Process for the Consolidation of Homogenous and Reliable CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2010Saeed Maleksaeedi In this work, a combined process, called centrifugal gel casting (CGC), was proposed for the fabrication of homogenous and reliable monolithic and composite ceramics starting from submicrometer-sized powders. This method exploits the advantages of both conventional gel casting (GC) and centrifugal slip casting (CSC), while overcoming the limitations associated with the two methods. Via this process, a relatively low centrifugal force is applied to form a highly concentrated slurry in the mold cavity, which is then followed by in situ polymerization of slurry during gelation. In this work, concentrated alumina slurries with different solid contents from 45 to 65 vol% were consolidated by the three forming methods mentioned above. Various properties of green and fired products were measured and compared. Shorter processing time, lower centrifugal force, higher green strength, and minimal segregation are observed to be the characteristics of CGC in comparison with CSC. In situ elimination of bubbles with no need for degassing and the ability to remove heterogeneities, on top of high reliability and the potential to process higher viscosity slurries, are the main advantages of this method over the conventional GC. [source] Detection of interactions in experiments on large numbers of factorsJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES B (STATISTICAL METHODOLOGY), Issue 4 2001S. M. Lewis One of the main advantages of factorial experiments is the information that they can offer on interactions. When there are many factors to be studied, some or all of this information is often sacrificed to keep the size of an experiment economically feasible. Two strategies for group screening are presented for a large number of factors, over two stages of experimentation, with particular emphasis on the detection of interactions. One approach estimates only main effects at the first stage (classical group screening), whereas the other new method (interaction group screening) estimates both main effects and key two-factor interactions at the first stage. Three criteria are used to guide the choice of screening technique, and also the size of the groups of factors for study in the first-stage experiment. The criteria seek to minimize the expected total number of observations in the experiment, the probability that the size of the experiment exceeds a prespecified target and the proportion of active individual factorial effects which are not detected. To implement these criteria, results are derived on the relationship between the grouped and individual factorial effects, and the probability distributions of the numbers of grouped factors whose main effects or interactions are declared active at the first stage. Examples are used to illustrate the methodology, and some issues and open questions for the practical implementation of the results are discussed. [source] Aqueous two-phase systems strategies for the recovery and characterization of biological products from plantsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 9 2010Oscar Aguilar Abstract The increasing interest of the biopharmaceutical industry to exploit plants as economically viable production systems is demanding the development of new downstream strategies to maximize product recovery. Aqueous two-phase systems (ATPSs) are a primary recovery technique that has shown great potential for the efficient extraction and purification of biological compounds. The present paper gives an overview of the efficient use of ATPS-based strategies for the isolation and partial purification of bioparticles from plant origin. Selected examples highlight the main advantages of this technique, i.e. scaling-up feasibility, process integration capability and biocompatibility. An overview of the recent approach of coupling ATPSs with traditional techniques to increase bioseparation process performance is discussed. A novel approach to characterization protein from plants combining ATPSs and two-dimensional electrophoresis (2-DE) is introduced as a tool for process development. In the particular case of products from plant origin, early success has demonstrated the potential application of ATPS-based strategies to address the major disadvantages of the traditional recovery and purification techniques. This literature review discloses the relevant contribution of ATPSs to facilitate the establishment of bioprocesses in the growing field of high-value products from plants. Copyright © 2010 Society of Chemical Industry [source] Piecewise travelling-wave basis functions for wiresMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2006I. García-Tuñón Abstract This paper presents a method of moments (MoM) formulation for large thin-wire structures. In our approach, a modified version of the well-known Rao,Wilton,Glisson (RWG) basis functions for wires including a linear phase term is considered. This additional term allows an efficient representation of the travelling-wave modes on each wire, while it preserves the main advantages of RWG bases for arbitrarily complex wire topologies. The paper contains a detailed description of the algorithm used for the computation of the impedance matrix integrals. Finally, some results for scattering problems are presented to show the agreement with the conventional RWG-MoM solution. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 960,966, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21533 [source] | ||||||||||||||||||||||||||||||||||