scholarly journals Regression models and response surfaces to assess the external stability of soil nail walls

2021 ◽  
Vol 36 (2) ◽  
pp. 251-267
Author(s):  
S. Villalobos
Keyword(s):  
Regression Models ◽  
Response Surfaces ◽  
Soil Nail ◽  
External Stability

Reliability analyses of a prototype soil nail wall using regression models

2010 ◽  
Vol 2 (2) ◽  
pp. 71-88 ◽  
Author(s):  
G.L. Sivakumar Babu ◽  
Vikas Pratap Singh
Keyword(s):  
Regression Models ◽  
Soil Nail ◽  
Soil Nail Wall

Mixed Helical Labyrinth Groove Seal Optimization Using Computational Fluid Dynamics

2017 ◽  
Author(s):  
Wisher Paudel ◽  
Cori Watson ◽  
Houston G. Wood
Keyword(s):  
Kinetic Energy ◽  
Regression Models ◽  
Labyrinth Seal ◽  
Response Surfaces ◽  
Design Parameters ◽  
Labyrinth Seals ◽  
Ansys Cfx ◽  
Helical Groove ◽  
Groove Seal ◽  
Annular Seals

Non-contacting annular seals are used in rotating machinery to reduce the flow of fluid across a pressure differential. Helical and labyrinth groove seals are two types of non-contacting annular seals frequently used between the impeller stages in a pump. Labyrinth seals have circumferential grooves cut into the surface of the rotor, the stator, or both. They function to reduce leakage by dissipating kinetic energy as fluid expands in the grooves and then is forced to contract in the jet stream region. Helical groove seals have continuously cut grooves in either or both of the rotor and stator surfaces. Like labyrinth seals, they reduce leakage through dissipation of kinetic energy, but have the added mechanism of functioning as a pump to push the fluid back towards the high pressure region as it tries to escape. Previous work has shown that both labyrinth and helical groove seals with grooves on both the rotor and the stator have lower leakage than seals with grooves on just one surface. The goal of this work is to analyze seals with helical grooves on one surface and labyrinth grooves on the other. Designs for both helical stator, labyrinth rotor and labyrinth stator, helical rotor will be simulated and the performance of each configuration will be compared. The primary variables considered for the designs of the seals include the width, depth, and the number of grooves for labyrinth seal and the width, depth, and the angle of the grooves for helical. The designs to simulate will be chosen using a Kennard-stone algorithm to optimally space them within the design space. Then, for both configurations, multi-factor quadratic regression models will be generated. Backward regression will be used to reduce the models to only statistically significant design parameters. From there, the response surfaces will be created to demonstrate the effects of each design parameter on the performance of the seal. Finally, optimal designs will be produced based on the regression models. These designs will be simulated to show the predictive power of the regression models. The simulations for this work will be run in ANSYS CFX for each seal type and configuration will be used to compare solutions for the two different types of designs to previous studies. The findings from this study is expected to show substantial decrease in leakage for a mixed helical-labyrinth seal in comparison to the seal with either helical or labyrinth grooves on both surfaces and thus will provide useful results needed to minimize amount of leakage and therefore improve the efficiency of the machine.

scholarly journals The Effects of Selective Laser Melting Process Parameters on Relative Density of the AlSi10Mg Parts and Suitable Procedures of the Archimedes Method

2019 ◽  
Vol 9 (3) ◽  
pp. 583 ◽  
Author(s):  
Shigang Bai ◽  
Nataliya Perevoshchikova ◽  
Yu Sha ◽  
Xinhua Wu
Keyword(s):  
Image Analysis ◽  
Relative Density ◽  
Selective Laser Melting ◽  
Laser Power ◽  
Regression Models ◽  
Processing Parameters ◽  
Response Surfaces ◽  
Laser Melting ◽  
High Relative Density ◽  
Scan Speed

In view of the importance of accurately measuring the relative density of a selective laser melted (SLMed) part for optimizing the selective laser melting (SLM) processing parameters, suitable procedures of the Archimedes method considering the surface-connected cavities were proposed by comparing the results using the Archimedes method with image analysis. The effects of the SLM processing parameters on the relative density of AlSi10Mg were investigated using the proposed procedures of the Archimedes methods and image analysis. Fourteen SLMed samples were produced by different SLM processing parameters according to Doehlert Matrix. The regression models correlating relative density and three SLM processing parameters (laser power, scan speed, and hatching distance) were built and the optimum parameter combination to get a high relative density was obtained. By plotting the response surfaces and contours of the regression models, it was found that the relative densities are both higher at the combination of the higher scan speed, higher power, and lower hatching distance and at the combination of a lower scan speed, a moderate laser power, and a optional hatching distance. It was also found that the parameter of hatching distance is the crucial parameter to get a high relative density and to get high mechanical property.

scholarly journals Evaluation of the optimal operation conditions using response surface methodology for the treatment of DMP by electrocoagulation

2015 ◽  
Vol 17 (2) ◽  
pp. 248-256 ◽  
Keyword(s):  
Stainless Steel ◽  
Response Surface Methodology ◽  
Response Surface ◽  
Current Density ◽  
Regression Models ◽  
Negative Impact ◽  
Electrochemical Techniques ◽  
Optimal Operation ◽  
Response Surfaces ◽  
Removal Efficiencies

<div> <p>Phthalic acid esters, commonly called as phthalates, are of a common use in the industrial activities and are known with their hazardous impact on the environment and on humans such as endocrine disrupting agents, carcinogenic and toxic effects. These adverse effects have led to increasing interest and research on the treatment and control of phthalates. Over the past two decades, there has been growing interest in the use of electrochemical techniques such as electrocoagulation (EC) for the treatment of organic pollutants particularly toxic organics. During the course of EC, where iron or stainless steel electrodes are used as electrodes, different mechanisms are operative for the elimination of organic matter, namely (a) adsorption (b) direct anodic oxidation, and (c) indirect oxidation of pollutants in the bulk solution. A statistical-based technique named as response surface methodology (RSM) is a powerful tool for modeling the complex systems (such as EC), evaluating the simultaneous effects of several factors (independent variables), and thus searching optimum conditions for desirable responses (dependent variables). Until now, RSM has not been used as a modeling and optimization tool for the EC treatment of phthalates. In this study, EC treatment, using stainless steel anode, of dimethyl phthalate (DMP), was investigated and optimized via RSM, central composite design (CCD). Initial DMP concentration (DMP<sub>o</sub>; 20-100 mg L<sup>-1</sup>), current density (J<sub>c</sub>; 4.5-22.5 mA cm<sup>-2</sup>), electrolyte concentration (NaCl, 750-1750 mg L<sup>-1</sup>), treatment time (t<sub>r</sub>; 60-180 min) were selected as critical process parameters while DMP, total organic carbon (TOC) removals and electrical energy consumption (EEC, in kWh m<sup>-3</sup>) values were selected as the responses. The EC process was optimized to improve the abatements of DMP and TOC and to reduce the EEC values. Separate validation experiments were conducted for each initial DMP concentrations at optimum EC conditions established by the software module to check the goodness of fit and quality of the regression models. According to the established second-order polynomial regression models, DMP, TOC removal efficiencies and EEC values were affected by the process variables in the following decreasing order; J<sub>c</sub>&gt;t<sub>r</sub>&gt;DMP<sub>o</sub>&gt;NaCl (negative impact), t<sub>r</sub>&gt;DMP<sub>o</sub> (negative impact)&gt;J<sub>c</sub>&gt;NaCl (negative impact) and t<sub>r</sub>&gt;J<sub>c</sub>&gt;NaCl (negative impact)&gt;DMP<sub>o</sub> (negative impact), respectively. Analysis of variance indicated that the experimental design models obtained for the EC treatment of aqueous DMP solutions in terms of the model pollutant and mineralization were statistically significant. The response surfaces of DMP established between initial DMP concentration and current density showed that DMP removal efficiencies can be enhanced by increasing the current density to a certain value indicating that an optimum value of current density exists for maximum DMP removal.</p> </div> <p>&nbsp;</p>

scholarly journals Regression Models Describing Rosa hybrida Response to Day/Night Temperature and Photosynthetic Photon Flux

1991 ◽  
Vol 116 (4) ◽  
pp. 609-617 ◽  
Author(s):  
Douglas A. Hopper ◽  
P. Allen Hammer
Keyword(s):  
Plant Growth ◽  
Response Surface ◽  
Regression Models ◽  
Response Surfaces ◽  
Rosa Hybrida ◽  
Stem Diameter ◽  
Stationary Points ◽  
Photon Flux ◽  
Photosynthetic Photon Flux ◽  
Bud Formation

A central composite rotatable design was used to estimate quadratic equations describing the relationship of irradiance, as measured by photosynthetic photon flux (PPF), and day (DT) and night (NT) temperatures to the growth and development of Rosa hybrida L. in controlled environments. Plants were subjected to 15 treatment combinations of the PPF, DT, and NT according to the coding of the design matrix. Day and night length were each 12 hours. Environmental factor ranges were chosen to include conditions representative of winter and spring commercial greenhouse production environments in the Midwestern United States. After an initial hard pinch, 11 plant growth characteristics were measured every 10 days and at flowering. Four plant characteristics were recorded to describe flower bud development. Response surface equations were displayed as three-dimensional plots, with DT and NT as the base axes and the plant character on the z-axis while PPF was held constant. Response surfaces illustrated the plant response to interactions of DT and NT, while comparisons between plots at different PPF showed the overall effect of PPF. Canonical analysis of all regression models revealed the stationary point and general shape of the response surface. All stationary points of the significant models were located outside the original design space, and all but one surface was a saddle shape. Both the plots and analysis showed greater stem diameter, as well as higher fresh and dry weights of stems, leaves, and flower buds to occur at flowering under combinations of low DT (≤ 17C) and low NT (≤ 14C). However, low DT and NT delayed both visible bud formation and development to flowering. Increased PPF increased overall flower stem quality by increasing stem diameter and the fresh and dry weights of all plant parts at flowering, as well as decreased time until visible bud formation and flowering. These results summarize measured development at flowering when the environment was kept constant throughout the entire plant growth cycle.

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