Established Regression Model Research Articles

Development of a hierarchical estimation method for anthropometric variables

Most regression models of anthropometric variables use stature and/or weight as regressors; however, these ‘flat’ regression models can produce large errors in estimation for anthropometric variables having low correlations with the regressors. A novel method was proposed which estimates anthropometric variables in a hierarchical manner based on the geometric and statistical relationships between the variables. This hierarchical estimation method first constructs estimation structures by analyzing the dimensional characteristics and geometric relationships of the anthropometric variables and then develops regression models based on the estimation structures. The hierarchical estimation method was applied to 60 anthropometric variables (selected for the design of an occupant package layout in a passenger car) by using the 1988 US Army anthropometric survey data. The hierarchical regression models showed a 55% increase in adjusted R 2 and a 31% decrease in SE on average when compared with corresponding flat regression models. Relevance to industry Regression models of anthropometric variables are of use in ergonomic design of products and workplaces when necessary body measurements are unavailable. The proposed hierarchical estimation method can be applied effectively to establish regression models of anthropometric variables, which have better statistical performance and geometrical meaning.

Assessment of grassland degradation near Lake Qinghai, West China, using Landsat TM and in situ reflectance spectra data

The severity of grassland degradation near Lake Qinghai, West China was assessed from a Landsat Thematic Mapper (TM) image in conjunction with in situ samples of per cent grass cover and proportion (by weight) of unpalatable grasses (PUG) collected over 1 m2 sampling plots. Spectral reflectance at each sampling plot was measured with a spectrometer and its location determined with a Global Positioning System (GPS) receiver. After radiometric calibration, the TM image was geometrically rectified. Ten vegetation indices were derived from TM bands 3 and 4, and from the spectral reflectance data at wavelengths corresponding most closely to those of TM3 and TM4. Regression analyses showed that NDVI and SAVI are the most reliable indicators of grass cover and PUG, respectively. Significant relationships between TM bands-derived indices and in situ sampled grass parameters were established only after the former had been calibrated with in situ reflectance spectra data. Through the established regression models the TM image was converted into maps of grass cover parameters. These maps were merged to form a degradation map at an accuracy of 91.7%. It was concluded that TM imagery, in conjunction with in situ grass samples and reflectance spectra data, enabled the efficient and accurate assessment of grassland degradation inside the study area.

A composite DOP approach to excluding bottom reflectance in mapping water parameters of shallow coastal zones from TM imagery

In this paper we proposed a composite depth of penetration (DOP) approach to excluding bottom reflectance in mapping water quality parameters from Landsat thematic mapper (TM) data in the shallow coastal zone of Moreton Bay, Queensland, Australia. Three DOPs were calculated from TM1, TM2 and TM3, in conjunction with bathymetric data, at an accuracy ranging from ±5% to ±23%. These depths were used to segment the image into four DOP zones. Sixteen in situ water samples were collected concurrently with the recording of the satellite image. These samples were used to establish regression models for total suspended sediment (TSS) concentration and Secchi depth with respect to a particular DOP zone. Containing identical bands and their transformations for both parameters, the models are linear for TSS concentration, logarithmic for Secchi depth. Based on these models, TSS concentration and Secchi depth were mapped from the satellite image in respective DOP zones. Their mapped patterns are consistent with the in situ observed ones. Spatially, overestimation and underestimation of the parameters are restricted to localised areas but related to the absolute value of the parameters. The mapping was accomplished more accurately using multiple DOP zones than using a single zone in shallower areas. The composite DOP approach enables the mapping to be extended to areas as shallow as <3 m.

A method for obtaining performance correlations of absorption machines

Several authors have developed models to be implemented in building thermal simulation programs for modelling absorption machines. Some anarchy has been detected related to the order of these models and the variables they consist of. In this paper, specific statistical tools were employed to establish regression models for the COP and the capacity of a water-lithium bromide single-effect absorption chiller. Experimental designs were used to obtain the data (values of COP and capacity) utilized to estimate the model parameters. The hypotheses initially adopted in the formulation of the models were modified at the sight of the results of subjecting the values obtained for the response variables to a variance analysis.

Biomass distribution patterns of ecotones between forest and swamp in Changbai Mountain

This paper studied the biomass distribution patterns ofLarix olgensis/swamp ecotones andBetula platyphlla/swamp ecotones in Changbai Mountain so as to provide theory foundation for the management of these nature resources, by setting up sample belts, investigating initial data along the environmental gradients change, and establishing regression models. By means of regression models, the biomass of communities, layers, tree species and organs was calculated. In this system, it was found that the community biomass increased gradually along the environmental gradients change from swamp to forest in Changbai Mountain. Furthermore, the ecotoneal biomass distributed mainly over tree layer. The tree biomass distributed mainly in two or three dominate tree species.

Chlorophyll-based model of seawater optical properties

A one-parameter model of the inherent optical properties of biologically stable waters is proposed. The model is based on the results of in situ measurements of inherent optical properties that have been conducted at different seas and oceans by a number of researchers. The results of these investigations are processed to force this model to agree satisfactorily with an established regression model that connects the color index with the chlorophyll concentration. The model couples two concentrations of colored dissolved organic matter (concentrations of humic and fulvic acids) and two concentrations of suspended scattering particles (concentrations of terrigenic and biogenic particles) with the chlorophyll concentration. As a result, this model expresses all inherent properties of seawater by a single parameter, the concentration of chlorophyll.

Influence of Design Parameters on Vertical Motions of Trawler Hull Forms in Head Seas

The influence of ship length, length to beam ratio, beam to draft ratio, prismatic coefficient, non-dimensional radius of gyration and Froude number upon significant amplitude of coupled heaving and pitching motions of trawler hull forms for six different sea states has been studied. For this purpose, 540 trawler hull forms have been generated from Doust trawler series to cover appropriate ranges of the design parameters. Seakeeping behavior of these forms has been studied by using an established ship motion computer program and regression models of significant seakeeping events have been derived. Through this study, it is believed that a method has been produced for the seakeeping evaluation of trawler forms during the early design stages, hence allowing for the design of safer and more seakindly trawler designs.

Mobile Phases in Reverse‐Phase HPLC for the Determination of Bitter Peptides in Cheese

ABSTRACTA cheese extract and a standard solution with a mixture of peptides and amino acids were used to evaluate the separations of reverse‐phase HPLC with alternative mobile phases to be used in conjunction with sensory evaluation. Acceptable resolution of components was observed when acetonitrile was replaced with absolute ethanol and trifluoroacetic acid was replaced with food‐grade hydrochloric acid. The average hydrophobicity and molecular weight of the peptides and amino acids were used to construct a linear regression equation with corrected retention times. Suspected bitter compounds were not confined to any one section of the chromatogram based on the established regression model.

The relation between thermal and pH changes in alginate impression materials

Objectives. The purpose of this study was to determine if pH changes are related to thermal changes during setting in alginate impression materials, and to investigate the possibility of establishing a mathematical model between thermal and pH changes. Methods. Thermal and pH changes were recorded during the 20 min gelation period following the mixing of five commercial alginate materials. The data obtained were plotted and statistically analyzed using a student's T-test, multiplicative, linear and reciprocal analyses at a significance level of p < 0.05. These analyses were used to determine the differences between various materials and to establish regression models between thermal and pH changes for each of the materials tested. Results. For all samples, the pH values fell within the first minutes from the alkaline range into the neutral and even into the acidic range, while the initial sharp fall in temperature was followed by a subsequent gradual increase. Differences in the final gel structures of the alginate materials were shown to be related to the differences in thermal and pH changes during setting. This could be expected from their various chemical compositions such as the variety of components, the chemical forms of principal components and the proportion of each component. Significance. This work contributes to the development of a mathematical model relating pH changes and thermal changes to form a basis for the correlation between chemical properties and characteristics in practical use.

The Colonization of Isolated Patches of Nettles (Urtica dioica L.) by Insects

This paper discussed the change pattern between environmental gradients and community structure, productivity and plant diversity of forest-swamp ecotones, and the mechanism forming those community's traits, which could supply a theoretical basis for conserving and managing the biological resources of ecotonal communities. By setting up sample belts along the environmental gradients on three kinds of ecotones between forests and swamps in Changbai Mountains and through investigating initial data and establishing regression models, the authors studied the dynamic pattern of species composition, diameter class and age class of dominant species, plant diversity, community productivity of forest-swamp ecotone communities with environmental gradients. The results showed that the distribution patterns of community structure characteristics, plant diversity and community productivity were consistent with the changes of environmental gradients of forest-swamp ecotones. Along the environmental gradient from swamp to forest, the displace of dominant species happened, and the species number increased by positive exponent. The diameter distribution of trees decreased by inverse curve, and the age class of trees was suited to cubic distribution. The plant diversity increased by quadratic, and the community biomass increased by cubic power curve along the environmental gradients. The above-mentioned results suggested that the relationships between communities and environmental gradients were closely related.