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Design and analysis of experiments
... The needed number of experiments (N) depends on number of variable (q) and was estimated according to the following equation (Montogomery, 1984): ...
... In accordance with eq.(3), twenty-nine experiment were carried out with four operating conditions. Also, the form of a quadratic (second order model) polynomial is illustrated by the following equation (Montogomery, 1984): where Y is the predicted response, X is the coded value of the independent variable and A is a coefficient. At the present study, the central composite design was used for optimization of the adsorption process and to evaluate the effects and interactions of the process variables. ...
The adsorption of Cr (VI) from aqueous solution by spent tea leaves (STL) was studied at different initial Cr (VI) concentrations, adsorbent dose, pH and contact time under batch isotherm experiments The adsorption experiments were carried out at 30°C and the effects of the four parameters on chromium uptake to establish a mathematical model description percentage removal of Cr (VI). The
analysis results showed that the experimental data were adequately fitted to second order polynomial model with correlation coefficients for this model was (R2 = 0.9891). The optimum operating parameters of initial Cr (VI) concentrations, adsorbent dose, pH and contact time were 50 mg/l, 0.7625 g, 3 and 100 min, respectively. At these conditions, the maximum percentage removal of Cr (VI) was 92.88%. The amounts of Cr (VI) adsorbed onto STL were highly affected by the solution pH value. Equilibrium data was modeled with Langmuir and Freundlich models isotherms. Langmuir model is found very well represent the equilibrium data with correlation factor is close to unity than the Freundlich model. The maximum monolayer adsorption capacity was found to be 47.98 mg/g at optimum conditions. The saturated adsorbent was regenerated by base treatment and found to be reuse efficiently after fourth cycle
at optimum conditions as well as for safe disposal of base that contains high concentration of Cr (VI) is precipitated as barium chromate.
... I used accelerated failure-time regression to evaluate adult life expectancy, i.e., the number of days from eclosion to death, in response to age, leafwing species, seasonal form, sex, forewing length, and experimental living conditions. Accelerated failuretime models are generalized linear models for which a number probability distributions can be tested, each with a direct link to how the probability of mortality and the instantaneous risk of mortality changes with age (Fox, 2001). I evaluated the appropriateness of four probability distributions, and in doing so I tested three alternative hypotheses; mortality was constant over all ages (exponential), mortality increased or decreased monotonically (Weibull), or mortality increased to maximum at some age then decreased (log-logistic and lognormal). ...
... I evaluated the appropriateness of four probability distributions, and in doing so I tested three alternative hypotheses; mortality was constant over all ages (exponential), mortality increased or decreased monotonically (Weibull), or mortality increased to maximum at some age then decreased (log-logistic and lognormal). To select among these probability distributions, I evaluated statistical significance of the scale parameter, which estimates the age effect on mortality (Fox, 2001), and also compared the values of each model's Akaike's information criteria (AIC), which estimates the fit of the model relative to the number of parameters used (Burnham and Anderson, 2002). ...
Surviving inhospitable periods or seasons may greatly affect fitness. Evidence of this exists in the prevalence of dormant stages in the life cycles of most insects. Here I focused on butterflies with distinct seasonal morphological types (not a genetic polymorphism) in which one morphological type, or form, delays reproduction until favorable conditions return, while the other form develops in an environment that favors direct reproduction. For two butterflies, Anaea aidea and A. andria, I tested the hypothesis that the development of each seasonal form involves a differential allocation of resources to survival at eclosion. I assayed differences in adult longevity among summer and winter forms in either a warm, active environment or a cool, calm environment. Winter form adults lived 40 times longer than summer form but only in calm, cool conditions. The magnitude of this difference provided compelling evidence that the winter form body plan and metabolic strategy (i.e. resource conservatism) favor long term survival. This research suggests that winter form adults maintain lowered metabolic rate, a common feature of diapause, to conserve resources and delay senescence while overwintering.
... The ÀNOVA table for response diameter is given in Table 7. The ANOVA table shows that both factors have the significant effect ( p-value < 0.05) on the diameter but the interaction effect is not significant (p-value ≥ 0.05) at 5% level [37]. Consequently, the analysis is carried out again by excluding the interaction term. ...
Six Sigma is a structured and systematic approach to performance and quality improvement. Six Sigma is a rigorous methodology consists of five major phases, namely definition, measure, analysis, improvement, and control for problem solving. A lot of case studies have been published and many large organizations have reported financial benefits by the application of Six Sigma methodology. This paper is a case study on reducing the bearing end plate reworks in a machining process through the application of Six Sigma methodology. The study focuses on reducing the rework due to thickness and diameter variation. From the list of identified potential causes, two causes, namely tool type and coolant pH are shortlisted as root causes. The optimum values of tool type and coolant pH, which would simultaneously optimize the diameter and thickness, are identified using the design of experiments and Taguchi's loss function approach. The implementation of optimum settings shows that the capability of the machining process to meet the customer requirements on thickness and diameter has substantially improved and rework has reduced.
The analyzes were aimed at demonstrating the influence of parameters describing the deformation of the structure on the uncertainty of critical force, and the impact of technological imperfections on stress uncertainty in compression conditions. In a linear buckling analysis, the problem is considered only for the initial, permanent state of the stiffness matrix. In the case of demonstrating the influence of initial deformations on the behavior of the structure under load, it is necessary to visualize changes in stiffness over time. To this end, a non-linear MES analysis was carried out, which will take into account local changes in the stiffness of the model through a gradual increase in the load. Thus, the difference in stiffness is taken into account, which in the linear problem is infinite. The analysis was used to examine the local and global sensitivity of the parameters describing: plating thickness as well as deformation caused by the technological process on the stress value reduced by Huber hypothesis, and the value of normal stress. To take into account the influence of non-specified values of the magnitude of geometric deviations, and their simultaneous influence on the range of obtained results, the Experimental Planning Method and the Surface Method of Answers were used.
Functional magnetic resonance imaging is one of the most commonly used neuroimaging techniques in cognitive neuroscience. Its influence had a central role in establishing the experimental side of the field. Given this, we consider that its status as a source of evidence has not been sufficiently dealt within the philosophical literature. We focus on this issue from the standpoint of the classical problem of defining the scope of localizationist approaches in neuroscience. We attend to the way this tension unfolds today, considering some recent examples of neuroscientific approaches that tackle the dynamic character of the brain's large scale activity. We take into account a number of limitations that functional magnetic resonance imaging presents, distinguishing those of them whose treatment involves not merely technical issues. On the basis of an analysis of some ways researchers deal with them, we claim that there is a considerable extent in which this kind of neuroimaging studies can be oriented according to general assumptions and theoretical considerations. We conclude that this particular theoretical permeability is a main factor affecting the technique's status as neuroscientific evidence.
The aim of present work is to study the removal of phenol presents in industrial wastewater using the local sawdust.The considered real of the four factors were(100-500) mg/l, (0.1-1) gm, (3-9) and (20-180) min for initial phenol concentration, adsorbent dose, pH and contact time, respectively, on the removal capacity has been studied. Statistical analysis of the results showed the significance of the individual factors and their interactions on both adsorption process. Box-Wilson design of experiments was adopted to find a useful relationship between the four variables and the removal efficiency. The experimental data collected by this method is successively fitted to a second order polynomial mathematical model.The optimum conditions for the removal of phenol within the experiment range of variables studies were 130 mg/lof initial phenol concentration, 0.82 gm of adsorbent dose, natural pH value of 6.7 and 120 min of contact time. Under these conditions the maximum removal efficiency was 91.6%. Batch kinetic and isotherm studies were carried out to evaluate the effect of initial phenol concentration, adsorbent dose, pH and contact time. A comparison of mathematical model applied to the adsorption of phenol was evaluated for the Langmuir and Freundlich adsorption models. It was found that the equilibrium data agree very well with the Langmuir and Freundlich models.
A new approach is developed for identifying suitable reaction coordinates to describe the progression of rare events in complex systems. The method is based on the forward flux sampling (FFS) technique and standard least-square estimation (LSE) and it is denoted as FFS-LSE. The FFS algorithm generates trajectories for the transition between stable states as chains of partially connected paths, which can then be used to obtain "on-the-fly" estimates for the committor probability to the final region, p(B). These p(B) data are then used to screen a set of candidate collective properties for an optimal order parameter (i.e., reaction coordinate) that depends on a few relevant variables. LSE is used to find the coefficients of the proposed reaction coordinate model and an analysis of variance is used to determine the significant terms in the model. The method is demonstrated for several test systems, including the folding of a lattice protein. It is shown that a simple approximation to p(B) via a model linear on energy and number of native contacts is sufficient to describe the intrinsic dynamics of the protein system and to ensure an efficient sampling of pathways. In addition, since the p(B) surface found from the FFS-LSE approach leads to the identification of the transition state ensemble, mechanistic details of the dynamics of the system can be readily obtained during a single FFS-type simulation without the need to perform additional committor simulations.
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