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Scaling Analysis (scaling + analysis)
Selected AbstractsScaling Analysis of the Effect of Binder Content and Binder Distribution on the Gas Permeability of Porous Green CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2008Jeong Woo Yun Two models have been developed to describe how variations in binder content and binder distribution influence the specific surface and the gas permeability of porous media. In the Core-Shell model, a shell of binder surrounds each ceramic particle, and the specific surface increases with decreasing volume fraction of binder. In the Multi-Sphere model, binder particles occupy the interstices between the ceramic particles, and the specific surface generally decreases with decreasing volume fraction of binder. The variation in the permeability with binder content predicted by each model is different as compared with the case of a constant specific surface. [source] Enhancement of electrokinetically driven microfluidic T-mixer using frequency modulated electric field and channel geometry effectsELECTROPHORESIS, Issue 18 2009Deguang Yan Abstract This study reports improved electrokinetically driven microfluidic T-mixers to enhance their mixing efficiency. Enhancement of electrokinetic microfluidic T-mixers is achieved using (i) an active approach of utilizing a pulsating EOF, and (ii) a passive approach of using the channel geometry effect with patterned blocks. PDMS-based electrokinetic T-mixers of different designs were fabricated. Experimental measurements were carried out using Rhodamine B to examine the mixing performance and the micro-particle image velocimetry technique to characterize the electrokinetic flow velocity field. Scaling analysis provides an effective frequency range of applied AC electric field. Results show that for a T-mixer of 10,mm mixing length, utilizing frequency modulated electric field and channel geometry effects can increase the mixing efficiency from 50 to 90%. In addition, numerical simulations were performed to analyze the mixing process in the electrokinetic T-mixers with various designs. The simulation results were compared with the experimental data, and reasonable agreement was found. [source] Scaling analysis of water retention curves for unsaturated sandy loam soils by using fractal geometryEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2010C. Fallico Fractal geometry was deployed to analyse water retention curves (WRC). The three models used to estimate the curves were the general pore-solid fractal (PSF) model and two specific cases of the PSF model: the Tyler & Wheatcraft (TW) and the Rieu & Sposito (RS) models. The study was conducted on 30 undisturbed, sandy loam soil samples taken from a field and subjected to laboratory analysis. The fractal dimension, a non-variable scale factor characterizing each water retention model proposed, was estimated by direct scaling. The method for determining the fractal dimension proposed here entails limiting the analysis to the interval between an upper and lower pressure head cut-off on a log-log plot, and defining the dimension itself as the straight regression line that interpolates the points in the interval with the largest coefficient of determination, R2. The scale relative to the cut-off interval used to determine the fractal behaviour in each model used is presented. Furthermore, a second range of pressure head values was analysed to approximate the fractal dimension of the pore surface. The PSF model exhibited greater spatial variation than the TW or RS models for the parameter values typical of a sandy loam soil. An indication of the variability of the fractal dimension across the entire area studied is also provided. [source] On the spatial scaling of seismicity rateGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2005G. Molchan SUMMARY Scaling analysis of seismicity in the space,time,magnitude domain very often starts from the relation ,(m, L) =aL 10,bmLc for the rate of seismic events of magnitude M >m in an area of size L. There is some evidence in favour of multifractality being present in seismicity. In this case, the optimal choice of the scale exponent c is not unique. It is shown how different values of c are related to different types of spatial averaging applied to ,(m, L) and what are the values of c for which the distributions of aL best agree for small L. Theoretical analysis is tested using the California data. [source] Electric field controlled electrospray deposition for precise particle pattern and cell pattern formationAICHE JOURNAL, Issue 10 2010Jingwei Xie Abstract Photolithography, soft lithography, and ink jetting have been used for automated micropattern fabrication. However, most of the methods for microfabrication of surface pattern are limited to the investigation of material properties of substrates with high-cost and complex procedures. In the present study, we show a simple (single-step) yet versatile and robust approach to generate biodegradable polymeric particle patterns on a substrate using electrospray deposition through a mask. Various particle patterns including patterned dots, circles, squares, and bands can be easily formed and the features of particle patterns could also be tailored using different masks and electrostatic focusing effects. Furthermore, cell patterns can be achieved on the surface of particle patterns by blocking the areas without particle deposition on the substrate and culturing cells on the substrate. Polymeric particle patterns and cell patterns developed in this study could be used in the high throughput screening of sustained release formulations, cell-based sensing, and drug discovery. In addition to experimental results, an analysis of the associated electric field is used to investigate quantitatively the nature of focusing effect. Scaling analysis is also applied to obtain the dominate terms in electrospray deposition process. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Distribution of larval fishes among water masses in Onslow Bay, North Carolina: implications for cross-shelf exchangeFISHERIES OCEANOGRAPHY, Issue 6 2005A. M. QUATTRINI Abstract The Gulf Stream (GS) is a major oceanographic feature with potential to influence the recruitment of larval fishes to continental shelf habitats in the southeastern United States. To test the hypothesis that the GS is a source of certain larval fishes to Onslow Bay, North Carolina, we (i) classified water masses as shelf, GS, GS front (GSF), or GS/shelf mixture (GS/S); (ii) compared larval fish assemblages and concentrations among these water masses; and (iii) compared length,frequency distributions and length,concentration relationships of indicator and commercially important taxa among water masses. A total of 21,222 larvae were collected with bongo and neuston nets from April 2000 to December 2001. Non-metric multidimensional scaling analyses revealed distinct larval assemblages associated with different water masses. For bongo catches, bothids were abundant in all water masses, gobiids, callionymids, and labrids were abundant in shelf waters, and myctophids and scombrids were abundant in the GS. For neuston catches, carangids dominated in GS/S, GSF, and GS waters, whereas triglids were abundant in shelf water. Larval concentrations in neuston catches were lower in shelf waters and higher in GS and GSF waters. Concentrations of most taxa in bongo catches were low in the GS and higher in shelf waters. We used trends in myctophid (offshore/GS) and gobiid (shelf) length,concentration data as indicators of the sources of commercially important serranids. Length distributions and concentrations of larval indicator taxa suggested local, shelf spawning, and transport of larvae from offshore. [source] Introduction to Hydromechanical Well Tests in Fractured Rock AquifersGROUND WATER, Issue 1 2009Todd Schweisinger This article introduces hydromechanical well tests as a viable field method for characterizing fractured rock aquifers. These tests involve measuring and analyzing small displacements along with pressure transients. Recent developments in equipment and analyses have simplified hydromechanical well tests, and this article describes initial field results and interpretations during slug and constant-rate pumping tests conducted at a site underlain by fractured biotite gneiss in South Carolina. The field data are characterized by displacements of 0.3 ,m to more than 10 ,m during head changes up to 10 m. Displacements are a hysteretic function of hydraulic head in the wellbore, with displacements late in a well test always exceeding those at similar wellbore pressures early in the test. Displacement measurements show that hydraulic aperture changes during well tests, and both scaling analyses and field data suggest that T changed by a few percent per meter of drawdown during slug and pumping tests at our field site. Preliminary analyses suggest that displacement data can be used to improve estimates of storativity and to reduce nonuniqueness during hydraulic well tests involving single wells. [source] Assessing inter-beach differences in semi-terrestrial arthropod assemblages on Maltese pocket sandy beaches (Central Mediterranean)MARINE ECOLOGY, Issue 2008Alan Deidun Abstract The distinctiveness of macrofaunal assemblages on different sandy beaches in the Maltese Islands was previously suggested by different single-season studies. A multi-seasonal sampling programme using pitfall trapping was implemented on four Maltese beaches to test the occurrence of this phenomenon. A total of 29,302 individuals belonging to 191 species were collected over a 2-year period, during which the beaches were sampled once per calendar season. A total of 77 species were recorded from single Maltese beaches only, of which nine were psammophiles. Non-metric multidimensional scaling analyses of pitfall trap species-abundance data resulted in a weak separation pattern, with samples grouping mainly in terms of beach and island rather than in terms of season or year of sampling, No physical variable could conclusively explain these patterns. It is concluded that although operating on Maltese beaches, macrofaunal assemblage distinctiveness is weaker than originally thought and can be attributed to the presence/absence or abundance of just a few psammophilic species. It is postulated that this phenomenon may be related to the ,pocket beach' nature of Maltese beaches, where headlands on either side of the beach to a large extent prevent the occurrence of longshore currents, resulting in semi-isolation of the populations of psammophilic species. A large number of single-beach records reported in this study highlight the high degree of beta diversity and spatial heterogeneity of Maltese beaches, and the conservation importance of the individual beach macrofaunal assemblages. [source] Examining Contextual Effects in a Practice Analysis: An Application of Dual ScalingEDUCATIONAL MEASUREMENT: ISSUES AND PRACTICE, Issue 3 2007André F. De Champlain Practice analyses are routinely used in support of the development of occupational and professional certification and licensure examinations. These analyses usually survey incumbents to obtain importance ratings of (1) specific tasks and (2) knowledge, skill, and ability (KSA) statements deemed by subject matter experts as essential to safe and effective practice. Several researchers have made important criticisms of traditional practice analysis procedures, particularly the lack of attention to contextual constructs and the resulting problematic interpretation of mean importance ratings. The present study provides a framework for assessing the impact of context in practice analysis studies. It focuses on a practice analysis of a health profession that sought to enhance the meaning of incumbents' importance ratings by embedding the statements in the context of patient acuities. Results indicate that incumbents' importance ratings varied as a function of patient acuity. Dual scaling analysis was used to obtain a multidimensional visual representation of the associations between importance ratings and contextual content. The implications of the contextual component of the study design for future practice analysis studies are discussed as well as possible applications of this approach to professions in education. [source] Investigating the Dimensionality of Counterproductive Work BehaviorINTERNATIONAL JOURNAL OF SELECTION AND ASSESSMENT, Issue 1 2003Melissa L. Gruys The study investigated the dimensionality of counterproductive work behavior (CWB) by examining the relationships between various counterproductive behaviors. Utilizing a university alumni sample (N = 343), data was collected through both self,report and direct judgments of the likelihood of co,occurrence. Eleven categories of CWB were examined: (1) Theft and Related Behavior; (2) Destruction of Property; (3) Misuse of Information; (4) Misuse of Time and Resources; (5) Unsafe Behavior; (6) Poor Attendance; (7) Poor Quality Work; (8) Alcohol Use; (9) Drug Use; (10) Inappropriate Verbal Actions; and (11) Inappropriate Physical Actions. CWB items and categories were generally positively related. Multidimensional scaling analysis suggests that the CWB categories vary on two dimensions: an Interpersonal,Organizational dimension and a Task Relevance dimension. [source] Evaluation of pollination syndromes in Antillean Gesneriaceae: evidence for bat, hummingbird and generalized flowersJOURNAL OF ECOLOGY, Issue 2 2009Silvana Martén-Rodríguez Summary 1Current views about the predominance of generalization of pollination systems have stimulated controversy concerning the validity of pollination syndromes. In order to assess the extent to which floral characters reflect selection by the most important pollinators we evaluated pollination syndromes in a florally diverse plant group, the tribe Gesnerieae, a monophyletic plant radiation from the Antillean islands. 2The study species include representatives of three groups of floral phenotypes, two of which chiefly correspond to ornithophilous and chiropterophilous syndromes. The third group includes subcampanulate flowers (characterized by a corolla constriction above the nectar chamber) with combinations of traits not fitting classic pollination syndromes. 3Pollination systems were characterized for 19 Gesnerieae species in five Antillean islands between 2003 and 2007 and supplemented with observations of four Gesneriaceae species from Costa Rica. Pollinator visitation and frequency of contact with anthers or stigmas were used to calculate an index of pollinator importance. Eleven floral traits including morphology, phenology and rewards were used to assess clustering patterns in phenotype space. 4Multidimensional scaling analysis of floral traits resulted in two clusters comprising: (i) tubular, red to yellow-flowered species with diurnal anthesis, (ii) bell-shaped-flowered species; two groups of floral phenotypes were evident within the latter cluster, campanulate nocturnal and subcampanulate flowers. Correlations between pollinator importance values and floral axes revealed strong associations with the expected pollinators, hummingbirds for tubular flowers, and bats for campanulate flowers; subcampanulate-flowered species had generalized pollination systems including bats, hummingbirds and insects. Discriminant analysis of the multivariate set of floral traits correctly classified 19 out of 23 species into the predicted pollination categories. 5Synthesis. This study provides support for classic hummingbird and bat pollination syndromes, demonstrating the importance of pollinator-mediated selection in the floral diversification of Antillean Gesnerieae. However, there was evidence for generalized pollination systems in species characterized by a unique morphological trait (corolla constriction), but with variable combinations of other floral traits. These findings suggests that floral phenotypes might also evolve under selection by various functional groups of pollinators, and underscores the importance of considering the presence and effectiveness of all floral visitors in pollination studies. [source] Characterization of Electrical Properties of Li(FexAl1,x)5O8 Solid Solutions by Impedance SpectroscopyJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2000Shuichi Arakawa To examine polaronic transport properties in Li(FexAl1,x)5O8 spinel solid solutions, a scaling analysis for their conductivity spectra and modulus spectra was performed. As in the case of ionic conductors, two significant parameters of a crossover frequency and a power-law exponent were extracted from the conductivity spectra which displayed the universal dynamic response behavior. Both the mobility and the concentration of carriers were successfully determined from the crossover frequency. The power-law exponent and the stretching parameter obtained from the modulus spectra varied with composition, implying that the increase in Fe concentration would enhance the Coulomb interactions between small polarons. [source] Scaling and correlation analysis of galactic imagesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2001P. Frick Different scaling and autocorrelation characteristics and their application to astronomical images are discussed: the structure function, the autocorrelation function, Fourier spectra and wavelet spectra. The choice of the mathematical tool is of great importance for the scaling analysis of images. The structure function, for example, cannot resolve scales that are close to the dominating large-scale structures, and can lead to the wrong interpretation that a continuous range of scales with a power law exists. The traditional Fourier technique, applied to real data, gives very spiky spectra, in which the separation of real maxima and high harmonics can be difficult. We recommend as the optimal tool the wavelet spectrum with a suitable choice of the analysing wavelet. We introduce the wavelet cross-correlation function, which enables us to study the correlation between images as a function of scale. The cross-correlation coefficient strongly depends on the scale. The classical cross-correlation coefficient can be misleading if a bright, extended central region or an extended disc exists in the galactic images. An analysis of the scaling and cross-correlation characteristics of nine optical and radio maps of the nearby spiral galaxy NGC 6946 is presented. The wavelet spectra allow us to separate structures on different scales like spiral arms and diffuse extended emission. Only the images of thermal radio emission and H, emission give indications of three-dimensional Kolmogorov-type turbulence on the smallest resolved scales . The cross-correlations between the images of NGC 6946 show strong similarities between the images of total radio emission, red light and mid-infrared dust emission on all scales. The best correlation is found between total radio emission and dust emission. Thermal radio continuum and H, emission are best correlated on a scale of about , the typical width of a spiral arm. On a similar scale, the images of polarized radio and H, emission are anticorrelated, a fact that remains undetected with classical cross-correlation analysis. [source] Analysis of heat transfer in autoclave technologyPOLYMER COMPOSITES, Issue 5 2001Vincenza Antonucci In autoclave technology, polymer based composites are manufactured under the application of pressure and heat. The heat transferred between the energy carrying fluid and the bag-composite-tool element activates exothermic curing reactions, leading to composite consolidation. The convective heat transfer mechanism is the most relevant aspect controlling the rate of chemical and physical transformations associated with composite curing. Moreover, the fluidodynamic regime that results from the interactions between the autoclave and the tool geometry, even if totally predictable in theory, is unattainable in practice. In this study, the heat transfer phenomena occurring during the autoclave manufacturing cycle have been analyzed. The assumption of a negligible through-the-thickness thermal gradient led to simplified energy balance equations. In this case, the thermal evolution of the manufacturing elements has been completely determined by two parameters: the global convective heat exchange coefficient, setting the rate of the heat transfer between the autoclave environment and the bag-composite-tool element, and the adiabatic temperature rise, establishing the relevance of the polymerization exotherm. A scaling analysis has been performed in order to identify the dimensionless parameters controlling the autoclave process. The developed semitheoretical methodology has been extensively tested by comparison with experimental data from an industrial autoclave. [source] Cultural Orientation, Ethnic Affiliation, and Negative Daily Occurrences: A Multidimensional Cross-Cultural AnalysisAMERICAN JOURNAL OF ORTHOPSYCHIATRY, Issue 2 2004Adital Ben-Ari PhD The present research focuses on cultural variations in the experience of daily stresses and strains. It simultaneously examines the experiences of daily hassles among people holding different cultural orientations (individualistic vs. collectivist) and different socioethnic groups (Jews and Arabs). Data were gathered from 662 Jewish and 300 Arab Israeli respondents by means of a random telephone number dialing. Differences were found in self-related hassles between individuals holding different cultural orientations and in family-related hassles between members of different ethnic affiliations. Multidimensional scaling analysis revealed a different configuration of relations among hassle domains in four groups of Ethnic Affiliation X Cultural Orientation, yielding a continuum from most typical individualists to most typical collectivists. with groups in cultural transition found in between. [source] | ||||||||||||||||